US 3894250 A
Apparatus for power positioning and holding of an outboard marine drive includes a manual trim angle selection input signal generator. A position sensitive signal generator in the form of a Hall cell or a resistor is secured on the gimbal ring unit with a movable element set in accordance with and by the movement of the marine drive. A comparator provides a pair of output signals in accordance with the relative magnitude of the two signals and depending upon whether drive is to be raised or lowered. The output signals are similarly connected through amplifying and switch isolating circuitry to actuate an electric motor and hydraulic pump unit to raise or lower the stern drive until the position sensor and the manual input are nulled. A slight dead band maintains stable operation as the stern drive is moved to a new trim position. A fail-safe circuit prevents malfunctioning if the sensing system open circuits.
Description (Le texte OCR peut contenir des erreurs.)
United States Patent [191 Hager et a1.
Related U.S. Application Data  Division of Ser. No. 329,726, Feb. 5, 1973, Pat. No.
 U.S. C1 307/309; 114/144 A, 115/34 R; 115/41 R; 115/41 HT  Int. Cl....... H0lr 5/00; B63b 41/00; B60q 1/26  Field of Search 307/278, 309; 1 14/144 A, 114/144 R, 235 B; 115/34 A, 34 R, 41 R, 41
 References Cited UNITED STATES PATENTS 3,641,965 2/1972 Schmiedel...................... 115/41 HT 3,688,133 8/1972 Flachsbarth 307/309 3,739,738 6/1973 41144 R luutmn l t I r l I l [451 July 8,1975
Primary Examiner-Stanley D. Miller, Jr. Attorney, Agent, or Firm-Andrus, Sceales, Starke & Sawall 57] ABSTRACT Apparatus for power positioning and holding of an outboard marine drive includes a manual trim angle selection input signal generator. A position sensitive signal generator in the form of a Hall cell or a resistor is secured on the gimbal ring unit with a movable element set in accordance with and by the movement of the marine drive. A comparator provides a pair of output signals in accordance with the relative magnitude of the two signals and depending upon whether drive is to be raised or lowered. The output signals are similarly connected through amplifying and switch isolating circuitry to actuate an electric motor and hydraulic pump unit to raise or lower the stern drive until the position sensor and the manual input are nulled. A slight dead band maintains stable operation as the stern drive is moved to a new trim position. A fail-safe circuit prevents malfunctioning if the sensing system open circuits.
6 Claims, 8 Drawing Figures PMEHTED L 8 I975 8 94 2 5 0 SHEET 1 HALL CELL POSITION SENSOR FOR OUTBOARD DRIVE APPARATUS This is a division of application Ser. No. 329,726, filed Feb. 5, 1973 and now US. Pat. No. 3,834,345.
BACKGROUND OF THE INVENTION This invention relates to automatic positioning drives for angular positioning of an outboard drive unit.
Outboard propulsion drive units are widely employed for marine drives particularly of the smaller pleasure boats and the like. Such units are preferably connected to the transom of the boat and mounted for angular orientation about a vertical axis for steering purposes and about a horizontal axis to permit optimum location of the propulsion unit in the water for optimum driving conditions. Hydraulic systems have been advantageously applied to power trim positioning of the out board propulsion units. For example, US. Pat. Nos. 3,434,448 and 3,434,449 disclose hydraulic systems wherein a piston and cylinder means is coupled to a stern drive for selectively positioning and holding of the stern drive unit in various angular orientation about a horizontal axis. The hydraulic system is driven from a suitable electric motor driven pumping unit having an appropriate hydraulic control system for raising and lowering of the stern drive unit. Generally such systems have employed a manual control at the steering station which the operator continuously operates until such time as the motor is at a desired position. The prior systems have therefore relied on the operator sensing an optimum condition. Alternatively, meters have been electrically coupled to the stern drive unit and positioned in accordance with the angular drive trim position. The variable resistor unit is connected in the circuit of a meter mounted adjacent to the operator and provides a visual indication of the angular setting time position.
Although the prior art devices have permitted power trim positioning systems, they have relied upon the direct attention of the operator either through a subjective sensing of optimum motor positioning, visual viewing of the motor position or of a meter with adjustment of the trim until an optimum condition is believed to have been established. Thus, the operators attention is, in essence, divided between the setting of the trim control and the operation of the propulsion unit. Further, in such systems, the set trim position changes during operation such as a result of interaction with the water and/or objects in the water or as a result of minor hydraulic leakage. For example, rapid acceleration or running over a stump or the like may cause the marine propulsion unit to move from the set position without necessarily returning to the set position after disturbing forces are removed. The operator must, therefore, provide a more or less continuous attention to the trim run positioning of the propulsion unit. This may require the operator's attention under conditions representing a hazardous diversion from the driving of the boat.
SUMMARY OF THE PRESENT INVENTION The present invention is particularly directed to a power lift system for automatically setting the marine propulsion unit in a selected trim position as a result of a single angle selection input, with the system holding the trim position for all normal operating conditions. Generally, in accordance with the present invention,
the automatic trim system includes a manually actuated signal generator for producing a signal related to a desired trim angle. An automatic sensing unit is coupled to a power unit and generates an output signal proportional to the angle position with respect to a reference. The two signals are connected to a comparator, the output of which provides an output for raising and lowering of the propulsion unit. The comparator preferably provides a pair of on-off signals for selectively raising and lowering of the marine propulsion unit. Thus, the one signal actuates a power lift mechanism to raise the stem drive and the opposite signal correspondingly actuates the power lift unit to lower the marine propulsion unit. The drive unit is thus automatically positioned until a null signal condition is established, at which time the drive unit is held in the preset desired position. If the trim angle should be changed due to any operating condition, the system will automatically reposition the drive unit to the preset condition.
In accordance with a further novel aspect of the invention, the apparatus is provided with a time delay which will be sufficient to keep the system from selfcorrecting itself under minor disturbances such as those associated with wave bounce and the like. The apparatus may further include a pressure responsive cutout which opens the drive position circuit if a high pressure is applied to the propulsion means, such as encountered if passing over a log. This permits the standard log jumping" with subsequent automatic reconnection of the trim control. Further, electronic circuitry can be employed to minimize the power consumption by the control system and thereby adapt the unit to the usual marine drive system.
The system, in accordance with a particularly novel aspect of the present invention, includes a dead band selected in accordance with the coasting characteristics of the drive unit including the hydraulic system. The dead band is selected to prevent overlap between adjacent selected angles.
In accordance with a further novel aspect of the present invention, the position sensor is a Hall cell sensor including a Hall cell transducer in combination with a magnetic member, with the cell and magnetic unit mounted for relative movement as a part of the drive unit. The Hall cell sensor transduces the sine wave of flux density to a related sine wave of voltage in response to the relative angular orientation of the Hall cell and the magnetic unit. The output is amplified and preferably buffered with a pair of emitter follower transistors to produce a double-ended output sufficient to drive an operational amplifier, the output of which is connected as an input to a comparator amplifier. The sensor circuitry includes filtering means to attenuate any radio frequency signal resulting from the ignition system of the marine propulsion unit and an offset adjustment means to adjust the offset of the Hall device. The system is preferably powered from a suitable voltage regulator means.
The Hall cell amplifier and emitter follower circuit may advantageously be formed as an integrated circuit unit with the Hall cell mounted in fixed relation to the propulsion drive unit. A doughnut shaped magnet is secured to the movable portion of the stern drive, for example, to the pivot shaft mounting and is rotated about the Hall cell to impress an operative flux upon the Hall cell which varies as a sine wave with the rotation or angular orientation of the propulsion drive unit. The comparator and drive circuitry may be separately mounted in a suitable control mounted inboard of the motor of the boat. Thus, in the preferred circuitry an operational amplifier means including a separate pair of operational amplifiers is connected as a comparator to compare the output of the Hall cell sensor and a preset DC signal. The output of one operational amplifier is connected to selectively drive an up switching amplifier and the output of the other operational amplifier is connected to drive a down switching amplifier. The outputs of the switching amplifier are connected through suitable relays or other switching means to reversibly drive an electric motor. The electric motor, in turn, is coupled to reversibly drive a hydraulic pump unit for corresponding raising and lowering of the propulsion drive unit until such time as the position sensing signal is nulled with the input signal. The control circuitry may further include a stabilizing network to eliminate the effects of vibration and to insert the desired angular dead zone which will permit the drive unit to coast past the equilibrium position by approximately one degree in either direction without re-energization of the system.
Further, as previously noted, the US. Pat. 3,641,965 discloses a resistive sensor for providing an output signal proportional to the angular orientation of the drive unit. As noted therein relatively simple and inexpensive linear resistors are preferably employed. However, the output as noted is linear with the position and, consequently, such an inexpensive resistor does not provide the required sine wave signal compatible with a system employing a Hall cell sensor. Applicant has found, however, that for the limited angular positioning required of a marine propulsion unit, a linear resistor in series with an appropriate fixed resistor generates a variable voltage which approaches a sine wave voltage versus angular displacement and is such as to permit highly satisfactory operation as the input to the Hall cell signal processing circuit. The resistive sensitive system may be desirable to minimize the expense and to avoid certain temperature stabilization required with Hall cell units.
As the sensing systems are preferably mounted to the propulsion unit there is a danger that the circuit will become open circuited due to wear or water contamination, corrosion or the like, particularly where the resistive sensing network is employed. Under such conditions the voltage may rise to provide a turn-on signal to the power lift means tending to lower the propulsion drive unit to its maximum down position with no means for the operator to return it to a higher position. This can obviously create an extremely dangerous operating condition particularly when the boat is under power. The present invention desirably provides a safety circuit to positively prevent the operation of the lowering power circuitry under open circuit conditions. The safety circuit in accordance with a further novel aspect of the present invention may employ a Zener diode means or the like connected to sense the input voltage from the resistance position sensor and actuate an interlock switch such as a transistor in response to an open circuit condition. The interlock switch positively prevents energizing of the lowering circuitry. The same voltage signals holds the lifting circuit in the preferred construction. The safety circuit preferably includes an integration means such as a resistor-capacitor to produce a delay in the actuation of the fail-safe circuit and thereby permit a momentary open circuit condition. Thus, in the resistance sensor element, the wiper may momentarily create an open circuit condition when moving from one winding turn to the next and erroneously operate the safety circuit if a delay means is not introduced.
The present invention thus provides a reliable automatic drive for accurately locating and positioning of an outboard marine propulsion drive unit.
BRIEF DESCRIPTION OF THE DRAWINGS The drawings furnished herewith illustrate preferred constructions of the present invention in which the above advantages and features are clearly disclosed as well as others which will be readily understood from the following description:
In the drawings:
FIG. 1 is a side elevational view of an inboardoutboard drive unit mounted on the transom of a partially shown watercraft, with various trim positions shown in phantom line illustration;
FIG. 2 is a fragmentary rear view of the watercraft and stem drive unit shown in FIG. I;
FIG. 3 is an enlarged fragmentary side elevational view of the stern drive unit shown in FIG. 1 more clearly illustrating the Hall cell mounting;
FIG. 4 is a vertical section taken on line 4-4 of FIG.
FIG. 5 is a block diagram of an automatic trim control system constructed in accordance with the present invention and applied to control a stern drive unit such as shown in FIG. 1;
FIG. 6 is a schematic circuit diagram of a system corresponding to that shown in FIG. 5 and employing a Hall cell position sensor mounted as a part of a stern drive unit shown in FIG. 1;
FIG. 7 is a schematic circuit similar to FIG. 3 illustrating an embodiment employing a resistance sensor and a novel fail-safe circuit; and
FIG. 8 is a schematic circuit of a simple differential relay embodiment.
DESCRIPTION OF THE ILLUSTRATED EMBODIMENT Referring to the drawings and particularly to FIG. 1, an outboard propulsion unit or assembly in the form of a stern drive unit 1 is shown mounted on the transom 2 of a partially shown watercraft 3. The stern drive includes a lower drive unit 4 and a bracket mounting assembly 5 for movably mounting and supporting of the drive unit from the transom 2. The bracket assembly 5 includes an intermediate gimbal ring 6 which pivotally supports the drive unit 1 upon a generally transverse horizontal axis 7 for selective tilt movement of the unit in a generally vertical plane. The gimbal ring 6 is in turn pivotally supported on a generally vertical axis 8 by the outer transom bracket 9 to provide for and permit movement of the drive unit 4 in a generally horizontal plane for purposes of steering the movement of the watercraft 3.
The drive unit 4 more particularly includes the usual propeller 10 which is drivingly connected to an engine 1 I mounted inboard of the watercraft 3. The propeller 10 is selectively rotatable in opposite directions in accordance with operation of suitable reversing gear positioning means not shown to provide for a corresponding forward and reverse thrust respectively for the watercraft 3. Further, the drive controls include a suitable remote speed and directional control unit connected by an electrical, mechanical cable system or the like not shown to permit convenient location of the operation, for example, adjacent a forward control station 12 of the watercraft 3. In addition, hydraulic power means are provided for supplying hydraulic liquid to a pair of cylinder piston means l3 connected to the opposite sides of the stern drive unit 1 functioning as hydraulic shock absorbing means as well as stern drive angular positioning or trim positioning power means. Thus, as more fully described in the previously referred to US. Pat. Nos. 3,434,448 and 3,434,449, the piston-cylinder means 13 are connected to a hydraulic gear pump 14 which is reversible driven by a reversible electric motor 15 to selectively supply liquid to the opposite sides of the cylinder-piston means 13, thereby permitting the powered extension and retraction thereof with a corresponding angular orientation or positioning of the stern drive unit 1 about the horizontal axis 7. As the above mounting and positioning of the stern drive may take any desired form and construction, no further description thereof is given other than that necessary to clearly describe the present invention.
In the operation of a watercraft which is driven from an outboard propulsion means such as a stern drive unit, the watercraft is preferably started with the drive unit 1 in the lowered depending full line position shown in FIG. 1. This aids the movement of the boat to the plane position. However, when the boat is on a plane, it is desirable to re-position the drive unit 1 further outward for maximum efficiency and speed as disclosed in the previously referred to US. Pat. No. 3,641,965. Under normal operating conditions various trim angles might be desirably employed. Further, the drive unit 1 may be raised upwardly to maximum position for trailing or low power operation. The present invention is particularly directed to provide an automatic drive and positioning control system which will permit selection of a given angle and the holding of such given angle automatically and in response to the operator merely actuating a suitable input positioning device to a selected angle position without the necessity for continued attention and monitoring of the system. Thus, generally, in accordance with the present invention, a trim angle selection unit 17 is provided adjacent to the operating station 12 and may conveniently be in the form of a multiple switch unit adapted to select any one of a plurality of preselected angles between a reference zero position and a maximum raised position. Thus, for example, a highly satisfactory automatic control system has been constructed providing for the selection of the seven different angles of 0, 35, 7.0", l0.5,l5, 22 and 44. Although pushbuttons, levers or position selection means can be used, a satisfactory selection unit 17 has been constructed with a rotary switch having an input knob 18 that could be moved to any one of the angle positions. The trim control system further includes a stern drive position sensitive signal means 19 coupled to the unit I and the signals of the selection unit 17 and signal means 19 are compared and processed to automatically and directly establish the angular movement and positioning of the stern drive unit 1 and is continuously operative to maintain such trim angle position.
Referring particularly to FIG. 5, a block diagram of the automatic trim control system of the invention is illustrated in which the manual input control 17 is shown providing one input to a comparator amplifier 20, the opposite input of which is connected to the position sensor 19. The output of the position sensor is a signal directly related to the angular positioning of the drive unit 1 and of a character related to the signal from the unit 17. The comparator 20 compares the two signals and provides a lift signal or a drop signal at a pair of corresponding lines 21 and 22, depending upon the relative magnitude of the two input signals. Thus, if there is a difference between the selected angle and the actual angle, a signal will appear at one or the other of the two output lines. These signals are similarly processed and in particular the control signal is amplified through similar amplifiers 23 and 23a and connected to actuate and up-relay 24 or a down-relay 25. The relays 24 and 25 in turn connect power to the electric motor 15 to reversibly operate the electric motor in accordance with the operation of the relays to thereby reversibly drive the hydraulic pump 14. The control system will automatically establish the trim angle and will reset the trim angle if it is changed for any reason under operation; for example, due to rapid acceleration, running over a stump or the like. The operator can select any one of the given angles without a great deal of attention or distraction from the normal operation of the watercraft.
Referring particularly to FIG. 6, schematic circuit diagram of an automatic trim control system is shown employing a Hall cell position sensing unit coupled to the stern drive unit, as shown in FIGS. 1-4 and functioning as a position sensor.
The Hall sensor 19 preferably is constructed as an integrated Hall cell circuit unit having a Hall cell 27 connected to a closely regulated power supply 28. A resistor-capacitor network 29 connects the supply 28 to the battery 29a and functions as a low pass filter to attenuate radio frequency that might be produced by the ignition system, not shown. Thus, in a practical application, the Hall cell was connected to a 5.6 volt regulated voltage.
The output of the Hall cell 27 is connected to a differential amplifier 30 which produces a double-ended output, each of which is coupled through a buffering emitter transistor 31 to a second amplifier 32 to provide an amplified voltage signal related to the Hall cell voltage at the output line 320. A pair of resistors 33 one of which is made adjustable, is connected to the input of the differential amplifier 30 to adjust the offset of the Hall device 27. The several circuit elements of the sensor 19 are, as noted, preferably formed as a single integrated circuit.
The output of the Hall cell 27 is controlled by an annular permanent magnet 34 which as shown diagrammatically in FIG. 6 is polarized diametrically of the magnet on a line generally normal to the diametrical line through the Hall cell. The magnet 34 is mounted for angular rotation about its own axis and is angularly oriented with respect to the Hall cell 27, as more fully shown in FIGS. 3 and 4. The effective component of the flux impressed upon the Hall cell 27 changes or varies in accordance with a sine wave function as the angular orientation or position of the magnet 34 with respect to the Hall cell 27 changes. The Hall cell 27 thus transduces the sine wave of magnetic flux to a corresponding sine wave voltage signal.
As illustrated in FIGS. 3 and 6, for the lowermost position of the drive unit 1, the Hall cell 27 is aligned with the periphery of the magnet 34 at essentially ninety degrees to the north and south poles. Although this is not the position of maximum flux and therefore signal level, it is the position of the maximum rate of signal change for any given small angle movement. This is particularly advantageous when applied to positioning of a marine drive unit, which is normally positioned between a vertical or position and a raised 55 position. The angular positioning between approximately 0 and l is quite significant in the propulsion of an outboard unit and consequently maximum accuracy is desired in that range. The sine wave voltage signal provides maximum voltage change per degree at the zero crossover axis as a result of the maximum slope and almost linear characteristic of the wave at that point. This also permits use of a relatively narrow voltage range; for example, 2.5 volts for the zero degree angle setting to 8.2 volts for a maximum or 55 angle setting. Although the voltage change per degree of angular movement in the upper range or last l5 is substantially less, the angular position is not as significant for operating the propulsion means and is therefore readily employed.
The output of the cell 27 is amplified and coupled through the emitter followers 31 to prevent loading of the sensor circuit. The amplified output is impressed upon a second amplifying stage 32 through series coupling resistors 35 and 36 and a resistor 37 to ground which sets the source impedance of the second amplifying stage. A paralleled RC feedback network includes a variable resistor 38 and a fixed capacitor 39. The variable resistor 38 permits adjustment of the gain of the second amplifying stage while the feedback capacitor limits the band width of the operational amplifier and protects it from spurious oscillation.
The output is thus an amplified signal, taken with respect to ground, which is directly related to the angular orientation of the stern drive unit 1 with respect to the zero or reference position.
The output is applied as one input to the comparator 20, which, as shown in FIG. 6, is preferably an operational amplifier means including a pair of operational amplifiers 40 and 41 for driving of the respective switching amplifiers 23 and 23a. Each of the amplifiers 40 and 41 is similarly constructed and includes a corresponding non-inverting input 42 and 43 and an inverting input 44 and 45. The non-inverting input 42 and the inverting input 45 are connected through individual series coupling resistors 46 and 46a to the ungrounded output of the angle section unit 17. Individual coupling resistors 47 and 47a connect the inverting input 44 and the non-inverting input 43 to the sensor 19. The sensor connected input terminals 43 and 44 of amplifier 40 and 41 are further connected to ground through suitable bypass capacitors 48 which, with the coupling resistors define low pass signal filters in the input circuit.
The selection unit 17 includes a voltage dividing network including a fixed resistor operational connected to the battery 29a with a regulated power supply 50 providing a regulated voltage to the selection unit 17 and the comparator circuit 20. The opposite leg of the voltage dividing network includes the rotary switch assembly having a movable contact 51 selectively engaging one of seven different contacts 52, related sequentially to the trim angles 0, 35, 7, l0.5, 22 and 44 in accordance with the system heretofore discussed. Each of the contacts 52 is individually connected to ground via an angle related resistor 53 to complete the voltage dividing network, with the common connection or junction 530 between the fixed resistor 49 and the movable contact 51 connected to the inputs 42 and 45 of the opeational amplifier 40 and 41. Thus, each of the resistors 53 provides a different voltage division of the regulated voltage with a corresponding fixed reference or set voltage input to the operational amplifier. The sensor and the reference voltages are thus applied to both operational amplifiers 40 and 41, compared, and an appropriate output signal generated to null the system by repositioning of the stern drive unit.
The operational amplifier 40 includes a paralleled R-C feedback network 54 which interconnects the amplifier output line 55 to the non-inverting input 44. A similar R-C network 54a interconnects output line 56 of amplifier 41 to the non-inverting input 45. The capacitors of the feedback networks 54 and 54a limit the frequency response of the amplifier in order to prevent a frequency response high enough to cause positive feedback and unstable operation. The feedback resistors of the networks 54 and 54a in combination with the input resistors set the gain of the amplifier which is selected to be sufficiently high to maintain alternative full on and full off conditions at the lines 55 and 56 and provide a switching logic to the drive portion of the power tilt mechanism. A relatively low voltage appears at lines 55 and 56 with amplifiers 40 and 41 off and a relatively high voltage appears when such amplifiers are on: In a practical system, the voltage may change from 2.4 volts to 7 volts.
Thus, selection resistors 53 are selected to maintain the minimum voltage applied to the operational amplifier well below the low voltage operating limit at 0 centigrade, to thereby avoid possible erroneous operation with temperature. The stem drive unit is a relatively large load and will coast somewhat after a null condition is created. In accordance with an aspect of this invention, a dead band is introduced into the input circuit to allow for such movement. In the illustrated embodiment, a dead band bias voltage is established at the inverting input 45 of amplifier 41 and at the noninverting input 42 of amplifier 40. The input 45 is connected by a resistor 57 to the regulated power supply 50 while the noninverting input is connected by a resistor 58 to ground. The resistor 57 and 58 are selected such that the reference voltage is offset slightly and results in a slightly premature cutoff or nulling of the corresponding amplifier. The dead band is selected in accordance with the coasting characteristics of the stern drive mechanism and in accordance with a practical construction permits the stern drive unit to coast past an equilibrium position by one degree in either direction without afi'ecting the system.
For example, the reference voltages inserted by resistor 53 may be selected to vary the input voltage between 2.4 and 7 volts, with the resistors 57 and 58 causing the actual input voltage to be offset by 0.1 of a volt. Thus, if the selection unit is set to an intermediate position with four volts appearing at line 53a, the voltage at the non-inverting input 42 of the raising operational amplifier 40 would be 3.9 volts while the voltage at the lowering operational amplifier would be 4.1 volts. If the sensor output voltage is, for example, below such level as a result of the drive unit 1 being located below the select angle, the amplifier 41 remains off. The amplifier 40, however, is driven on because the inverting terminal 44 is at a lesser voltage than the non-inverting terminal 42. The unit 1 is driven up and the sensor voltage increases until a voltage 3.9 volts is impressed on both applifier 40 and 41. Amplifier 41 is off and remains off. This, however, nulls the output of amplifier 40 which then cuts off and terminates the positive drive. The drive unit 1 continues to coast toward the set position and stops. If it coasts slightly past the set position corresponding to the reference voltage of the selection unit 17, the offset of such voltage appearing at the opposite terminal prevents driving of the operational amplifier on, unless of course the coasting is excessive. in that case, the voltage output of sensor 19 compared to the set voltage differs by more than the offset voltage and reverses the drive.
For example, assume the coast is four degrees and thus in excess of two degrees dead band. The sensor voltage is then 4.3 volts equal to 3.9 volt cutoff voltage and the additional 0.4 volts for the 4 coast movement. The non-inverting input 43 of the lowering amplifier 41 is now above the set voltage of 4.l volts at the inverting terminal 45. As a result, amplifier 41 turns on and reverses the drive to properly re-position the drive unit 1.
Generally, the stern drive units of the assignee of this application are basically of two different varieties. One employs a relatively hydraulic cylinder means and moves at a relatively fast angular velocity, with a total angular displacement of about 50. The other system illustrated employs a somewhat larger hydraulic cylinder means moving at a somewhat slower angular velocity but with a total angular displacement of about 56. This difference in velocity results in a somewhat different amount of average coast and generally it has been found that the slower dual drive will stop approximately three-quarters of a degree before the desired position whereas the single drive will stop at approximately the desired position with the 2 dead band.
The amount of coast also depends on the amount of power applied to the propeller. Thus, with the stern drive trimmed down and under full forward power, the total coast may be such as to move beyond the dead band zone. However, with the present invention, the system will correct itself once and come back within the desired position.
The total dead band zone of two degrees in the system described is thus a compromise to adapt the unit to both systems while maintaining separation of the two adjacent trim settings at 3.5.
The difference in total angular displacement also requires somewhat of a comprise is a single system is to be applied to all the drives. Further, some margin of safety must be introduced into the system in order to compensate for normal manufacturing tolerances and the like as well as to allow a few degrees between the all down trim position and the all down mechanical stop. A practical system was designed for a variation in trim position between zero and forty-four degrees nominal. As a practical matter, the actual positions may, as a result of normal manufacturing tolerances and the like, vary between 40 and 48 from unit to unit. If close tolerance components are employed for the highest value sensing resistor as well as the interrelated voltage dividing and sensing resistors of and for the voltage regulator diode and the like, the variation can be substantially reduced. Thus, if one percent tolerance parts were employed, the system could be designed for nominal displacement of approximately forty-seven degrees with an expected total variation from unit to unit of about from 46 to 48.
Alternatively, the control circuits could be constructed for each particular stern drive by a proper selection of the bias resistive network to the comparator. The highest value position resistor 53 as well as the compensating dead band resistors 57 and 58, for example, could be properly selected for each design. This, of course, would require inventory of two separate control circuits, with the attendant expense and the like. The resistors 57 and 58 thus may be adjusted to provide a desired response to the inputs of sensor 19 and selective means 17 as applied to the amplifiers 40 and 41 of stage 20.
Sensor assembly 19 and comparator 20 are powered from the regulated supply 50 to provide reliable logic response. The regulator 50 may be any suitable construction, such as a Zener diode unit with a temperature compensating diode and stabilizing capacitors to produce the desired regulated voltage. The regulator 50 produces the desired operating voltage such as 9.2 volts.
The amplifier output lines 55 and 56 are similarly coupled to high gain amplifying and switching stages 23 and 23a which function as power switches and are shown as Darlington switching circuits. As each of the output lines is similarly connected, that for the raising or up line 55 is described, with the corresponding elements for the lowering circuit being identified by similar prime numbers.
The illustrated amplifier 23 includes a pair of transistors 61 and 62 which are connected as a Darlington pair, with the input base connected by a coupling resistor 63 to the comparator output line 53. A turn-on resistor 64 is connected between the base and the ground and emitter to complete the input signal circuit. The resistors 63 and 64 form a voltage divider which reduces the base voltage at the amplifier 23 below the switching level with the operational amplifier 40 off, and applying the relatively low voltage signal.
The output is taken at the collector with a negative feedback network including capacitor 65 which introduces a time constant in the system with a delayed turnon and rapid turn off to prohibit the system from correcting itself from each slight variation in position of the stern drive unit, such for example as associated with slight wave bounce. The switching and associated feedback circuit is more fully described in the copending application of James Hager and no further description is given herein.
The output switching as provided by the Darlington circuitry provides selective completion of the circuit to the relay 24, which has a winding 67 connected in series with the output circuit of the Darlington transistor unit to the battery power supply. The Darlington pair normally presents a high impedance or open circuit condition to the relay winding. When the Darlington pair is turned on, as a result of the tumon signal at the output line 55 of the amplifier 40, the Darlington connected transistors rapidly switch to full on to establish a very low impedance path thereby completing the energizing circuit through the relay winding. This, in turn, closes the related relay contacts 67-1 to provide power to the motor for energizing of the electric motor in a lift direction and thereby driving the pump 14 to power the hydraulic system to correspondingly raise the drive unit 1. As the drive unit 1 raises, the magnet 34 is correspondingly positioned and varies the effective flux supplied to the Hall cell 27 and correspondingly changes the voltage signal to the comparator 20 when the sensed signal corresponds in a predetermined manner to the set signal as determined by the positioning of unit 1.
If for any reason the drive unit 1 moves from the set position, the Hall cell 27 generates an offset signal to operate the relay 24 or 25. If the stern drive unit 1 is above the desired position, a signal appears at output line 56 which turns on the Darlington transistors 61' and 62' and completes the power circuit to the lower relay winding 68. This, in turn, results in the closing of the associated contacts 68-1 to energize the electric motor to operate in the opposite direction with the hydraulic pump 14 oppositely actuated to introduce hydraulic fluid into the piston-cylinder means 13 to lower the stern drive unit 1.
When the unit is again in the preset position, the magnet 34 is relocated with respect to the Hall cell 27 to establish a null condition to turn off the trim drive and establish the stable condition.
The operator may therefore conveniently control the trim position before and during running.
The Hall cell sensor 19 of FIGS. 5 and 6 is preferably constructed as a small compact and potted assembly which is mounted to the stern drive unit 1, as most clearly shown in FIGS. 3 and 4. A cup-shaped disc housing 70 includes a plurality of outer arcuate mounting slots 71 and 72 and is secured abutting the gimbal ring or member 6 by suitable cap screws 73 and 74 passing through the slots 71 and 72 and threaded into appropriately tapped openings 75 in the member 6. The housing 70 includes a central opening aligned with the horizontal shaft 76 which is rotatably journaled in the gimbal ring and defining the tilt axis support of the drive unit 4. The housing 70 includes a cylindrical recess or chamber 77 in the exterior face with a peripheral inner wall 78 of stainless steel or other similar nonmagnetic material. The Hall cell 27 and associated circuitry of unit 19 shown for example in FIG. 6 is located within the recess 77 which is then filled with a suitable potting material 79 such as an epoxy resin to physically support the elements and protect them from the severe environmental conditions encountered in marine use. The Hall cell 27 is diametrically located with respect to the shaft opening 75, as shown in FIG. 4. The annular or doughnut shaped magnet 34 is secured to the shaft 76 by a clamping nut 80 and located within the central opening of wall 78 of the housing 70, particularly in a common plane with the Hall cell 27. The magnet is diametrically polarized to establish a radially outwardly directed flux which is impressed upon the Hall cell 27. Thus, the nonmagnetic inner wall readily transmits the flux to the potted Hall cell. As described in connection with FIG. 6, a sine wave of flux is applied to the Hall cell in accordance with angular orientation of the drive unit with respect to the gimbal ring or member 6. A cover 81 may be secured to the housing to enclose the potted recess and the magnet.
If desired, the system can be employed with a resistance sensing element, similar to that described in U.S. Pat. No. 3,641,965 in place of the Hall cell 27. FIG. 7 is a schematic circuit corresponding to that of FIG. 6 with the substitution of a resistor position sensor 81 for the Hall cell unit 19 described above and additionally with a fail-safe circuit 82. Corresponding elements of FIGS. 6 and 7 are correspondingly numbered and no further description of the circuit is given other than to clearly describe the revision to the basic circuit. The resistor position sensor 81 includes a resistor card 83 with a movable wiper 84 rotatably mounted to scan the card. A wound resistor 85 is mounted on the card and connected between the ground and the input terminal of the operational amplifier 40 functioning as the comparator. The wiper 84in turn is connected to the corresponding input and thus selectively shorts a portion of the resistance from the circuit and simultaneously adjusts the voltage impressed on the input terminal. The wiper is coupled to rotate with drive unit 4, for example, by connection to shaft 76 as disclosed in U.S. Pat. No. 3,641,965. A fixed resistor 86 is connected between the input terminal of the comparator forming the common connection to the position sensor and the regulated power supply. The fixed resistor 86 and the variable resistor 85 constitutes a variable voltage dividing network with the variation of the lower leg being directly related to the angular displacement. With the series resistances connected to the regulated voltage supply, a non-linear output with angular displacements is generated at the common junction. Applicant has found that the voltage output varies approximately as a sine wave with angular displacement, at least over the limited number of degrees encountered for marine propulsion units such as stern drives wherein the movement covers essentially 55 of displacement. The voltage dividing network as described defines a curve which very closely approaches the sine wave curve and thus is completely suitable for direct substitution for the Hall cell circuit shown in FIG. 3. Further, the variable resistor 85 is adjusted to create an offset signal corresponding to a zero degree positioning of the drive unit 1 to stimulate the offset adjustment of the Hall cell, with the sine wave generated from that zero reference position.
When a resistive sensor is employed, an open circuit condition may be caused by the wear of the unit, water contamination, corrosion and the like. If the sensing circuit does open, the voltage applied to the input of the comparator from the regulated voltage supply rises as a result of the very high impedance presented by a total or partial maximum open circuit between the input terminal and ground. This would, of course, create a maximum turn on lower signal at the sensing output line connected by resistors 47 and 47a to the comparator 20 which in turn would lower the drive unit 1 to its lowermost position, with no means at the control of the operator for reversing or running the drive unit 1 to a lower position. Such a malfunction may create a particularly dangerous position under operating movement of the watercraft. To prevent this type of condition from arising, a safety circuit 82 is interconnected into the control system and in particular responds to an abnormal input voltage to positively prevent the lower system from being turned on.
The fail-safe circuit 82 in the illustrated embodiment of the invention is connected to the circuit of lowering amplifier 41 and particularly line 87 to the base of transistor 61' and to the sensor signal line 32a to the comparator resistors to hold line 87 at ground in response to an abnormally high input voltage at the sensor power terminal or line and thereby prevent turning on of the lower switch 23a and the associated relay 68.
More particularly, the fail-safe circuit 82 includes a single high beta transistor 88 connected between the line 87 and thus the base of transistor 61' and ground. A Zener diode 89 in series with resistor 90 connects the base of transistor 88 to the sensor line 91.
A small capacitor 92 is connected between the resistor and ground which defines an inegrating circuit holding the fail-safe circuit in the off condition for a momentary initial period of time with the input voltage above the 8.8 volts reference level. This is desirable to prevent actuation of the fail-safe circuit 82 during momentary or transient periods of abnormal voltages. Thus, in the usual wound resistor unit, the wiper 84 loses contact in moving from one winding turn to the next and would do so in the preferred linear resistor unit described. Zener diode 89 would be selected to provide a threshold detection of the voltage when it rises above a selected level greater than the voltage necessary to null the maximum voltage from the reference or selection unit 17. When diode 89 conducts, current is supplied to the transistor 88 which shorts the input to the lower circuit to ground. Thus, with a 9.2 volt regulated supply and a maximum input reference signal of 7 volts, the Zener diode 89 may be conveniently selected to respond to a signal of 8.8 volts.
The fail-safe circuit may take any voltage sensitive form which will detect an abnormal high voltage on the input of the sensor circuit or the like and positively prevent the malfunctioning of the circuit to lower the stern drive unit 1, particularly under running conditions. For example, a differential amplifying circuit may compare a fixed voltage with that at the sensor line and control a control switch in the lower drive circuit.
The circuit of F 1G. 7 otherwise functions in the same manner as that previously described to provide an automatic raising and lowering of the drive unit to various trim positions as a result of the simple input selection by the operator.
Further, the relatively large number of selections which can be made permit the positioning of the drive unit in a proper position under essentially all possible operating conditions.
In addition to the electronic signal processing, the trim control can employ a relatively simple comparison network for actuating of the trim positioning motor or the like. For example, FIG. 8 illustrates a simple differential relay system.
In FIG. 8, a control rheostat 96 and a trim indicator rheostat 97 have one end connected in common to the battery 98 and related movable taps connected to selectively energize a differential relay 99. The control rheostat 96 is mounted for manual adjustment. The trim indicator rheostat 97 is coupled to the drive unit for example as shown in previously referred to US. Pat. No. 3,641,965. The rheostat taps provide corresponding power signals in accordance with a desired trim angle and the actual trim angle.
The differential relay 99 includes a first winding 100 connected in series with the rheostat 96 and energized accordingly. The winding 100 is electromagnetically coupled to one end of an armature 101 which is centrally pivoted at 102. The armature 101 is, generally, a T-shaped member which is connected by a line to battery 98 and with the stem portion carrying suitable contacts including a first set of contacts 103 which are closed upon predetermined pivoting of the armature 101 toward the electromagnetic unit defined by winding 100. An opposed winding 104 is similarly connected into circuit with the rheostat 97 and is coupled to the opposite end of the armature 101. The electromagnetic force of the winding 104 tends to pivot the armature 101 in an opposite or counter-clockwise direction as viewed in F IG. 8. Selected pivotal movement in this direction results in closing of an oppositely disposed set of contacts 106. Thus, if the currents through the windings 100 and 104 are balanced or essentially balanced, the armature 101 is held in a central position with contacts 103 and 106 both open. Differential energization of windings 100 and 104 results in the closing of contacts 103 or 106 to provide corresponding energization of a pair of power relays 107 and 108. The power relay 107 is connected to the one side of the contacts 103 and ground such that when the contacts 103 close, power is supplied to the power relay winding 107 to close a related set of contacts 107-1. Similarly, power relay 108 is connected in circuit through the contacts 106 to control a related set of contacts 108-1. The contacts 107-1 and 108-1 are connected respectively in series with the corresponding forward and reverse windings of a reversible motor 109, for corresponding controlled energization thereof. The motor 109 is coupled to drive a pump 110 which in turn provides circulating fluid through an up-trim line 111 or a down-trim line 112 in accordance with the directional energization of the motor 109. The down-trim line includes a surge valve 113. ln accordance with a further novel aspect of the present invention, a differential pressure switch 1 14 is provided in the energizing circuit of the motor 109 to momentarily remove the automatic trim control under log jumping conditions. The differential pressure switch 114 includes a pressure sensor 115 which is connected in parallel with the surge valve 113. The pressure sensor 115 is coupled to control a normally closed switch 116 which is connected between ground 117 and the ground side of the motor 109. lf a back pressure is created on the drive unit resulting in a greater pressure on the down side line of the actuator in excess of the pump pressure at line 1 12 and thus a net back pressure, the switch 116 opens. This effectively opens the circuit for the control and permits the lower drive unit to move upwardly in a relatively unrestricted manner to clear an obstruction.
The operation of the embodiment shown in FIG. 8 is otherwise generally similar to that previously described. Thus, the current flow of the two windings of the differential relay 99 is in accordance with the resistance in the respective branches which in turn is proportional to the desired setting and the actual trim setting, with the current in the one coil or winding greater than in the other in an amount equal to the relay threshold leve, the corresponding contacts 103 or 106 close to provide corresponding energization of the appropriate power relay 107 or 108. This, of course, establishes the desired operation of the trim pump 1 10 to readjust the trim angle until such time as the trim angle sensing rheostat 97 again equals the preset rheostat 96. This then re-establishes the null condition with the trim unit at the desired position.
As in the previous systems, any disturbance or oil leakage may result in a corresponding change in the trim angle from the dial setting. This again operates the trim angle control to automatically reset the system.
Further, various safety features can, of course, be incorporated into the trim setting control of this invention. For example, an interlock relay may be interconnected to open when the ignition switch is turned off with a required manual reset switch. The interlock relay would remove the system until such time as the manual reset seitch is positively actuated. A simple onoff switch could, of course, be provided with reliance on the operator to turn off the switch whenever the ignition system is turned off. For emergency use, a direct override control could be provided at the trim pump to permit desired positioning if the automatic system malfunctions or the like.
In addition to the illustrated sensing devices, any other suitable sensors can be employed. For example, inductive and capacitive sensors can be readily applied within the broadest concept of the present invention as well as various photo devices such as photoresistive and photoemissive devices. Further, although the control setting dial is shown on the instrument panel of the boat, it may also be incorporated in the throttle control, the steering wheel hub or the steering column for convenient manipulation by the operator. It may also be desirable to have the control setting dial constructed to provide automatic indication of the setting position through the sense of touch by the operator such that he can maintain complete visual attention to the driving of the boat.
Various other designs can, of course, be incorporated in connection with each of the particular portions of the circuit and the like although that illustrated has been found to provide satisfactory operation. It may be desirable to employ a suitable stop means to prevent selection of the two uppermost positions while under power and thereby eliminate the possible danger of moving the drive unit (when running) upwardly out of the water. Other mechanical or electrical interlocks, not shown, can also be readily designed into the system to prevent such selection.
These and similar features can, of course, be readily provided for those skilled in the art and thus no further particular discussion or illustration thereof is given.
The present invention has been found to provide a relatively simple and reliable trim power control system and apparatus.
Various modes of carrying out the invention are contemplated as being within the scope of the following claims, particularly pointing out and distinctly claiming the subject matter which is regarded as the invention.
1. A Hall cell sensor for producing a sine wave signal proportional to tilt positioning of a pivotally mounted outboard drive unit, comprising Hall cell having a tubular housing having attachment means for supporting the housing in fixed relation with respect to the outboard drive unit, an annular magnetic means adjacent to said Hall cell and having attachment means for securing the magnetic means to the outboard drive unit coaxially with the axis of rotation of the drive unit, said magnetic means being diametrically magnetized to produce an operative flux field varying as a sine wave with angular orientation.
2. The Hall cell sensor of claim 1 wherein at least one of said attachment means is adjustable to produce offset of the cell voltage.
3. The Hall cell sensor of claim 1 including a differential amplifier connected to the output of the Hall cell and establishing a pair of floating output lines, a dual input operational amplifier, a pair of emitter follower circuits connecting the pair of floating output lines to the operational amplifier, said operational amplifier including a resistivecapacitive feedback network, a resistive bias adjustment to the Hall cell to establish a selected offset of Hall cell voltage, a regulated voltage supply, and a low-pass filter network connecting said Hall cell and said amplifier to the regulated voltage supply.
4. The Hall cell sensor of claim 1 wherein said housing includes a recess within which said Hall cell and a signal processing circuit components are mounted and interconnected, a potting material filling said recess to support said cell and circuit components, the housing having a wall adjacent the magnetic means which is non-magnetic.
5. The Hall cell sensor of claim 4 wherein said wall is formed of a solid material which is non-magnetic.
6. The Hall cell sensor of claim 4 wherein said circuit components include a differential amplifier connected to the output of the Hall cell and establishing a pair of floating output lines, a dual input operational amplifier establishing a single ended output signal, a pair of emitter follower circuits connecting the pair of floating output lines to the second operational amplifier.
UNITED STATES PATENT AND TRADEMARK OFFICE CERTIFICATE OF CORRECTION PATENT NO. 3, 894,250
DATED July 8, 1975 INVENTOR(S) 1 JAMES R. HAGER and HUGH E RIORDAN It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:
Column 1, Line 37, after "setting" cancel "time and insert trim Column 15, Line 5, after "reset" cancel "seitch" and insert switch Column 16, Line 24, before "feedback" cancel CLAIM 3 "resistivecapacitive" and insert resistive capacitive Sign! and Scaled this second Day of Deoember197$ [sen] A nest:
RUTH C. MASON C. IARSIIALI. DAMN Altestmg Officer (ommissiuner afferent: and "Ideal-1h
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