DE202004012388U1 - Surgical hand instrument with motorized rotary output for e.g. boring or milling, has single motor operated in high and low speed ranges by separate control procedures - Google Patents

Abstract

The instrument (10) has low and high speed ranges. It has two control procedures (A, B), one for each of these ranges. It has one motor (14).

Description

The The present invention relates to a surgical machine with a Electric motor, which has a rotor and at least two motor windings, and with a motor controller for controlling and / or regulating the electric motor.

Further The following is a procedure for operating a surgical Machine with an electric motor, which has a rotor and at least two Has motor windings, and with a motor controller for control and / or rules of the electric motor.

surgical Machines of the type described in the introduction are in numerous variants known, especially as drilling and milling machines or saws. she are operated by using control signals for the electric motor generated to operate it at a certain speed. Depending on the type of electric motor, speeds can up to 70,000 revolutions per minute can be achieved. By design However, the efficiency of electric motors is not at all speeds same, especially not always optimal.

It is therefore an object of the present invention, a surgical Machine and a method for operating a surgical machine so improve that in particular an efficiency of the electric motor essentially over the entire speed range can be optimized.

This The task is described in the case of a surgical machine Kind according to the invention solved, the existence Total speed range of the surgical machine in at least one lower speed range for low speeds and in at least an upper speed range for higher speeds is divided as the at least one lower speed range that the engine control is designed such that in the at least one lower speed range a first control and / or regulating methods for controlling and / or regulating the electric motor is feasible and that in the at least one upper speed range a second control and / or regulating methods for controlling and / or regulating the electric motor feasible is.

The Training according to the invention Known surgical machines has the advantage that each control adapted to a speed range of the electric motor and / or regulatory procedures can be applied. In particular, it would be conceivable that more than Two speed ranges are defined, each at the transition from one to the other speed range also the one used Control and / or regulation process is switched. To this Way can be not only optimize the efficiency of the electric motor during operation, but it leaves, for example also an actual speed of the electric motor during operation depending determine the speed optimized.

Advantageous it is when the first and / or the second control and / or regulation process is a Pulse Width Modeling (PWM) process. With this procedure can in particular DC motors in a simple manner operate optimized. In particular, sinusoidal current and voltage profiles can be generated by overlay digital voltage or Current signals with a carrier frequency.

According to one preferred embodiment of the Invention can be provided that the first control and / or Control method a space vector pulse width modulation (SVPWM) method is, in which all motor windings can be energized at the same time. The SVPWM process has counter usual Pulse Width Modulation (PWM) method has the advantage that all motor windings can be energized at the same time, so that even at particularly low Speeds a smooth, smooth operation of the electric motor is possible. Furthermore, starting the motor from standstill is essential improved that all Motor windings can be energized at the same time.

Especially economical and the machine becomes less maintenance-intensive when the electric motor a brushless DC motor is.

Preferably the electric motor is a sensorless electric motor. Below is to understand that none Speed detection sensors for determining an actual speed of the Electric motor provided or arranged on the electric motor. Such electric motors are much cheaper as motors that include sensors, and also simplifies Overall construction of the surgical machine. The reason for this is that less connections for the Motor must be provided. This also has the advantage that a dismountable surgical machine no corrosion problems can occur in contacts via which a connection of the engine control to speed detection and / or Position sensors can be manufactured. Such contacts are common applied with small voltages or currents, so that already a slight corrosion of the contacts to errors in the determination the actual speed of the electric motor can lead. Exactly this can in a machine according to the invention not happen.

Alternatively, it can be provided in an advantageous manner that the motor has speed detection sensors and that the motor control is designed in such a way that the first control and / or regulating method is a method for controlling and / or regulating the surgical machine, in which the motor control provides control signals for the Electric motor as a function of an actual speed determined with the speed detection sensors. The speed detection sensors can also serve to determine a position of the rotor of the electric motor. Use rotational speed detecting sensors, particularly at low rotational speeds of the electric motor, has the advantage that the rotational speed can be substantially determined more accurately than, for example, by detecting a (raft E lektro- M otorische- K) on the or the motor windings generated back EMF. The determination of the back emf is particularly suitable at higher speeds, since in this case higher induction voltages are generated and the signals determined can be processed better as a result.

On Particularly simple construction of the machine results when using a Hall system is provided for detecting an actual speed of the electric motor and when the Hall system includes the speed detection sensors. Hall sensors as speed detection sensors can especially small and integrated directly into the electric motor become.

According to one preferred embodiment of the Invention can be provided that a speed limit between the at least one lower and the at least one upper speed range unchangeable is. In this case, switching between the minimum two control and / or regulation procedures always with one desired Speed limit take place.

According to one another preferred embodiment The invention can also provide that a speed limit between the at least one lower and the at least one upper speed range variable is. Depending on the operating situation thereby switching between the at least two control and / or Change control procedures in a targeted manner. Switching points can then in the desired one Way can be varied.

On continuous switching between the at least two control and / or Control procedure can be avoid in a simple way that the engine control in such a way is trained that a Switching from the first control and / or regulation process to the second control and / or regulation method takes place at a first switching speed and that one Switching from the second control and / or regulation process to the first control and / or regulation method at a second switchover speed he follows. Two switching points can thus be defined, namely at the transition from low speed range in the higher speed range and vice versa. So it is possible separate the switching times, that is, a small variation of the Actual engine speed leads not necessarily immediately to switch to the other control and / or regulation procedure.

In principle, it would be conceivable that the first switching speed is less than the second switching speed. Very cheap it is, however, if the first switching speed is equal to or greater than is the second switching speed. Switching to the higher speed range thus takes place at a higher Switching speed instead of switching from the higher speed range to the lower speed range. This results in a quasi hysteresis curve with an area in which for certain speeds both one and the other control and / or regulatory procedure is applied, however dependent whether the speed of the electric motor increases or decreases.

in principle would it be possible, train the machine so that a Operator a desired Speed range specifies and the corresponding control and / or regulation process activated. According to one preferred embodiment of the However, the invention can be provided that the engine control in such a way is trained that Switching from the first control and / or Regulatory procedure in the second tax and / or regulatory procedure at the transition from at least one lower to at least one upper speed range, and vice versa, is done automatically. The operator must do this embodiment according to the invention the machine only specify the speed at which they the Want to operate the machine.

Especially The construction of the machine becomes simple when the electric motor is three Has motor windings. Such electric motors are numerous Variants, especially inexpensive, available.

The method of the type described at the outset can be improved by subdividing an overall speed range of the surgical machine in the at least one lower speed range for low speeds and in the at least one upper speed range for higher speeds than in the at least one lower speed range, in that the at least one lower speed range a first control and / or regulating method for controlling and / or regulating the electric motor is carried out and that in the at least one upper speed range a second control and / or regulating method for controlling and / or Rules of the electric motor is carried out.

With a surgical machine can advantageously be operated in this method be, in particular thus increasing their overall efficiency, because depending the speed of the electric motor can be the most suitable Control and regulatory procedures can be selected.

On can be particularly simple control a DC motor when the first and / or the second Control and / or regulation methods are pulse width modulation (PWM) methods.

In particular at low speeds and when starting the electric motor it particularly cheap if the first control and / or regulation method is a space vector pulse width modulation (SVPWM) method is in which all motor windings are energized at the same time. This method allows, especially at low speeds, to achieve an improved efficiency of the engine, as dependent the rotor position compared to conventionally energized electric motors forces exerted on the rotor by the energized motor windings are optimized can be.

Preferably an electric motor is used, which is a brushless DC motor is. Such motors are inexpensive and easy to maintain.

The Number of contacts on the surgical machine can be decrease when using an electric motor that is a sensorless Is electric motor. Furthermore, such motors are much cheaper in production.

According to one Another preferred variant of the method can be provided that the Engine has speed detection sensors and that the first control and / or Regulatory procedure a procedure for controlling and / or regulating the surgical machine, in which the motor controller control signals for the Electric motor depending on one provides actual speed determined with the speed detection sensors. In particular at low speeds, speed detection sensors can be used an actual speed of the electric motor easily and precisely determined.

Especially the implementation of the Procedure when a Hall system to detect an actual speed of the electric motor is provided and if the Hall system the speed detection sensors includes. Hall systems have been used in numerous applications proven. In particular can Hall sensors are designed to be particularly small and directly into the electric motor to get integrated.

Preferably remains a speed limit between the at least one lower and the at least one upper speed range when operating the Machine unchanged. In this way, the process is maximally simplified.

According to one another preferred variant of the method described above However, it can be provided that a Speed limit between the at least one lower and the at least an upper speed range during machine operation changed becomes. This procedure enables es, a switching speed value corresponding to a current operating situation increase.

Is cheap it when switching from the first control and / or regulation procedure in the second control and / or regulation procedure for a first Changeover speed occurs and if a changeover from the second control and / or regulatory procedures in the first control and / or regulatory procedure at a second switching speed. This allows Changeover points at the transition from the lower to the upper speed range, and vice versa, in the desired Set way. In particular, frequent switching can thus be avoided if the machine is running at speeds in the range of the changeover speed is operated. A constant Would toggle negatively affect the operation of the surgical machine, in particular disturb a smooth running.

Preferably the first switching speed is equal to or greater than the second switching speed. In order to there is a switch from the low speed range to the high Speed range preferably at a higher speed than vice versa.

Advantageous it is when switching from the first control and / or regulation procedure in the second control and / or regulation procedure during the transition from at least one lower to at least one upper speed range, or vice versa, is done automatically. An operator must be in this Case just a desired one Speed for the pretend surgical machine, but is not a possible switchover take care of different control and / or regulation procedures.

Especially the implementation of the Procedure when using an electric motor with three motor windings becomes.

The following description of a preferred embodiment of the invention is used in conjunction with the drawings for further explanation esterification. Show it:

1 : A schematic representation of a surgical battery machine;

2 : a circuit diagram of a motor control of the in 1 illustrated battery machine; and

3 : one to the circuit diagram in 2 Corresponding schedule for an operation of the in 1 shown battery machine.

In 1 is a whole with the reference symbol 10 provided surgical battery machine shown a housing 12 has in one part an electric motor 14 is arranged parallel to the longitudinal axis of this housing part, which is a drive shaft of the battery machine, not shown 10 drives. At the end of the drive shaft is a clutch 16 arranged, by means of which the battery machine 10 can be connected with tools of any kind, for example drills, milling cutters, chisels and, possibly via special couplings, also with saw blades.

From which the electric motor 14 receiving housing part of the housing 12 is a handle across 18 in which a power pack 20 can be introduced. The power pack 20 includes a rechargeable battery 22 as well as an engine control 24 , To start up the battery machine 10 are a gas pusher 26 and an operating mode selector switch 28 provided which is substantially parallel to a longitudinal axis of the electric motor 14 in the handle 18 can be pushed in.

With the electric motor 14 it is a sensorless motor, that is, there are no speed detection sensors for detecting a rotor movement and a position of a rotor of the electric motor 14 intended.

The engine control 24 is designed such that a speed range of the electric motor 14 is divided into two parts, namely a lower speed range 30 and an upper speed range 32 how this in 2 is shown schematically. It also allows engine control 24 , two different control and / or regulation methods for operating the electric motor 14 perform. On the one hand, this is a space vector pulse width modulation (SVPWM) method which is used in the 2 and 3 is denoted schematically by A. On the other hand, it is a conventional pulse-width-moluation (PWM) process which is used in the 2 and 3 is marked schematically with B.

In the case of an electric motor 14 with a speed detection system which has position sensors and speed detection sensors, the control and / or regulation method A could also be a control and / or regulation method in which an actual speed of the electric motor 14 determined by means of the speed detection sensors and by the engine control 24 is processed. In the space vector pulse width molulation (SVPWM) method and also in the conventional pulse width modulation (PWM) method, an actual speed of the electric motor is used 14 determined by determining the back emf.

With reference to the 2 and 3 The procedure for switching from control and / or regulation method A to control and / or regulation method B is explained in more detail below.

Activate the gas trigger 26 the battery machine is set by an operator 10 in operation. In 2 are start / stop with the reference symbol 34 Mistake. The operator increases the speed of the electric motor 14 , so the engine control 24 the control and / or regulation _method A off until the switching _speed D _{limit1 is reached} . As soon as the switchover _speed D _{limit1 is} reached, the engine control switches 24 automatically switch to control and / or regulation procedure B. Until the maximum speed D _{max of} the electric motor is reached 14 becomes the electric motor 14 from the engine control 24 operated in control and / or regulation procedure B. The speed requirement for the electric motor 14 reduced again by the operator, so is also for speeds of the electric motor 14 which are _lower than the switchover _speed D _{limit1 maintain} the control and / or regulating _method B until the switchover _speed D _{limit2 is} reached. The engine control only switches when the switching _speed D _{limit2 is reached} and the _{speed falls below} it 24 back to the control and / or regulatory procedure A. If the speed requirement is increased again, a switchover to control and / or regulating _method B takes place only after the switching _speed D _{limit1 has been exceeded} .

The consequence of this circuit diagram is that in 1 an overlap area between the lower speed range 30 and the upper speed range 32 is formed, the total with the reference numeral 36 is provided. In the overlap area 36 can the engine control 24 perform both the control and / or regulation process A and the control and / or regulation process B. Which method is carried out depends, however, on whether the speed _{requirement is} increased based on an actual speed below the switchover speed D _limit2 or is reduced from above the switchover _speed D _limit1 . Overall, the results in 2 shown hysteresis curve, on wel cher the overlap area 36 can be moved counterclockwise.

How the motor control works 24 is used to switch between the two control and / or regulation methods A and B. 3 clear. The starting point is a stationary electric motor 14 , If this is started, the engine control system leads 24 the control and / or regulation procedure A. The actual speed at time t _n is determined at periodic intervals. After determining the actual speed at time t _n , a _{query is made} as to whether the actual speed is less than the switchover speed D _limit1 . If the speed is less than the switchover speed D _limit1 , a _query is made as to whether the speed is 0. If this is the case, the engine control stops 24 the operation of the electric motor 14 , If the actual speed is less than the switchover speed D _limit1 , but greater than 0, then the control and / or regulation _method A is carried out.

If the actual speed determined at time t _{n is} greater than the switchover speed D _limit1 , the engine control switches 24 to the control and / or regulation procedure B. The actual speed at time t _{n + 1} is still determined at periodic intervals and then compared with the previously determined actual speed at time t _n . If the actual speed at time t _{n + 1 is} greater than the actual speed at time t _n , then the engine control system leads 24 continue the control and / or regulatory procedure B. However, if the actual speed at time t _{n + 1} is lower than the actual speed at time t _n , then the actual speed is compared with the changeover speed D _limit2 . If the actual speed is greater than the switchover speed D _limit2 , the engine control continues to carry out the control and / or regulating _method B. Otherwise the engine control switches 24 automatically to control and / or regulation procedure A.

Switching between the two control and / or regulation methods A and B has the particular advantage that a space vector pulse width modulation (SVPWM) method carried out at low speeds shows undesired damping effects at high speeds, which results in the engine result in losses and the efficiency of the battery machine ( 10 ) is adversely affected.

The Both control and / or regulation methods A and B can in the engine control system can be implemented in hardware or software.

Claims (13)

Surgical machine ( 10 ) with an electric motor ( 14 ), which has a rotor and at least two motor windings, and with a motor controller ( 24 ) to control and / or regulate the electric motor ( 14 ), characterized in that a total speed range ( 30 . 32 ) of the surgical machine ( 10 ) in at least one lower speed range ( 30 ) for low speeds and in at least one upper speed range ( 32 ) for higher speeds than the at least one lower speed range ( 30 ) is divided that the engine control ( 24 ) is designed such that in the at least one lower speed range ( 30 ) a first control and / or regulation method (A) for controlling and / or regulating the electric motor ( 14 ) is feasible and that in the at least one upper speed range ( 32 ) a second control and / or regulation method (B) for controlling and / or regulating the electric motor ( 14 ) is feasible. Machine according to claim 1, characterized in that this first and / or the second control and / or regulation method (A, B) is a pulse width modulation (PWM) method. Machine according to one of the preceding claims, characterized characterized that the first control and / or regulation method (A) a space vector pulse width modulation (SVPWM) method is, in which all motor windings can be energized at the same time. Machine according to one of the preceding claims, characterized in that the electric motor ( 14 ) is a brushless DC motor. Machine according to one of the preceding claims, characterized in that the electric motor ( 14 ) is a sensorless electric motor. Machine according to one of claims 1 to 4, characterized in that the electric motor ( 14 ) Has speed detection sensors and that the engine control ( 24 ) is designed such that the first control and / or regulating method (A) is a method for controlling and / or regulating the surgical machine ( 10 ), in which the engine control ( 24 ) Control signals for the electric motor ( 14 ) as a function of an actual speed determined with the speed detection sensors. Machine according to claim 6, characterized in that a Hall system for detecting an actual speed of the electric motor ( 14 ) is provided and that the Hall system includes the speed detection sensors. Machine according to one of the preceding claims, characterized in that a speed _{limit value} (D _limit1 , D _limit2 ) between the at least one lower and the at least one upper speed range ( 30 . 32 ) is unchangeable. Machine according to one of claims 1 to 7, characterized in that a speed _{limit value} (D _limit1 , D _limit2 ) between the at least one lower and the at least one upper speed range ( 30 . 32 ) is changeable. Machine according to one of the preceding claims, characterized in that the motor control ( 24 ) is designed such that a switchover from the first control and / or regulation _method (A) to the second control and / or regulation _method (B) takes place at a first switchover _speed (D _limit1 ) and that a switchover from the second control and / or or control _method (B) into the first control and / or control _method (A) at a second switching _speed (D _limit2 ). Machine according to claim 10, characterized in that the first changeover _speed (D _limit1 ) is equal to or greater than the second changeover _speed (D _limit2 ). Machine according to one of the preceding claims, characterized in that the motor control ( 24 ) is designed such that the changeover from the first control and / or regulation method (A) to the second control and / or regulation method (B) during the transition from the at least one lower to the at least one upper speed range ( 30 . 32 ) and vice versa, automatically. Machine according to one of the preceding claims, characterized in that the electric motor ( 14 ) has three motor windings.