US2804061A - Valve-actuating mechanism for internal combustion engines - Google Patents

Description

Aug.27,1957 J G GAMBLE 2,804,061

VALVE-ACTUATING MECHANISM FOR. INTERNAL COMBUSTION ENGINES Filed Jan. 4, 1955 2 Sheets-Sheet l INVENTOR S I g ATTORNEYS Aug. 27, 1957 .1. G. GAMBLE VALVE-ACTUATING MECHANISM FOR INTERNAL COMBUSTION ENGINES 2 Sheets-Slieet 2 Filed Jan. 4, 1955 INVENTOR mm X ATTORNEYS United States Patent 9 VALVE-ACTUATING MECHANISM FOR INTERNAL COMBUSTION ENGINES John G. Gamble, Milford, Conn.

Application January 4, 1955,.Serial No; 479,703 11 Claims. (Cl..123--90) This invention relates to valve-actuating mechanism for internal combustion engines and particularly to a mechanism for controlling the intake valves of such an engine so that the opening of the intake valves is responsive to the speed of the engine and to pressure existing within the manifold.

In the ordinary four-cycle internal combustion engine the valves are operated by cams fixed upon a cam shaft so that the valve remains open over a fixed period, expressed in degrees of cam shaft rotation, whether the engine is traveling at a high or low speed. It will be seen, therefore, that when the engine is traveling at a high speed or a relatively high R. P. M., the valves will remain open a shorter time measured in seconds or fractions of a second although they are heldopen for the same period expressed in degrees of rotation of the cam. As the cam shaft rotates at a greater speed when the engine operates at a higher speed, the shaft will rotate in a much shorter time through the arc during which the cam acts upon the valve tappet, and thus the valves will be held open over a shorter period measured in seconds than when the engine is operating at a relatively low R. P. M.

It is also true that the higher the speed of the engine the greaterwill be the demand for fuel, the engine acting as a pump to pump in fuel-laden air from the carburetor; If the engine speed is quite high and the demand for a fuel charge is great, the valves- Will be held open such a short time that the valveopenings will act to throttle or restrict thefuel-air flowto the cylinders ofthe engine, thus inhibiting full accommodation tothe cylinder vacuum. This will, of course, not only limit the speed of the engine, but, as a relatively small charge is drawn into the cylinder at each opening of the? valve, the designed compression ratiois not obtained on the compres sion stroke of the piston when such astarved condition exists.

This is, of course, a. well recognized principle, and standard stock cars are provided with a camof such a. shape that it: is a compromise between the. optimum for the lowest and highest speeds of the engine or one which is suitable at what might be termed an average speed; in racing cars thecarns are so made as-to hold the valves open a longer" time than in stock cars, and thus the valve-actuating. mechanism of a racing car is notsuitablefor slow speeds.

The same-1 problemeicists tosomedegree during periods of acceleration and: also is'present due to changes in load. For example, ifthe throttle valve of an internal combustion engine is opened to" a greater extent but the load uponthe enginetis correspondingly increased, the speed will. not be increased. Inthis case, however, it is desirable to have the valve held open during a longer periodin order to admit a greater quantity offuel in order to compensate for the increase in load; Under conditions where the engine is under load and. the throttle valveopening has been increased to take care of the load; the" manifold pressure will be higher than under ordinary conditions. U i r i It is, therefore, desirable to adjust the period during which the intake valves are open not only according to the speed of the engine, but also according to pressure in the manifold so as to take care of load conditions and acceleration. This is effected in the present instance by securing the valve cams upon a shaft movable axially of its length and effecting translating movements of this shaft not only in response to the speed of the engine but also in response to the pressure obtaining in the engine manifold. Thus whenever it is necessary the valve opening will be efiectively increased or decreased according to the demands of the engine and the conditions under which the engine is operating.

One object of the invention is to provide new and improved means for actuating the intake valves of an internal combustion engine.

A further object of the invention is the provision of means to actuate the valves of an internal combustion engine so that the valves will be held open over a greater period, expressed in degrees of rotation of the cam shaft, when the engine is operating at a high speed as compared with that which takes place when the engine is operating at a low speed.

A still further object of the invention is the provision of a. valve-operating mechanism for internal combustion engines such that the intake valves Will be held open over a greater or less period expressed in degrees of rotation of the cam shaft in response to conditions of acceleration or load. so that the greatest efficiency of the engine will be obtained.

Still another object of the invention is the provision of an adjustable cam member for actuating the intake valves of an internal combustion engine, the cam surface being of greater extent at one end of the cam than at the other whereby when the first end of the cam actuates the intake valve, the latterwill be held open a greater portion of the revolution of the cam shaft than when the smaller end serves to actuate the valve.

Still another object of the invention is to provide a valve-actuating mechanism of the character described above wherein the cam: has an active surface tapering in width. or in extent circumferentially and is mounted upon a translatable cam shaft, and means are provided to move the cam shaft axially in response to the R. P. M. of the engine.

Still another object of the invention is to provide mechanism for moving, the translatable cam shaft axially in response. to the pressure existing in the engine manifold.

To these and other ends the invention consists in the novel features and combinations of parts to be hereinafter described and claimed.

Inthe accompanying drawings:

Fig. 1 is a somewhat diagrammatic view of avalveactuating mechanism embodying my invention;

Fig. 2 is an enlarged view similar to Fig. 1, showing the cam-shaft-actuating mechanisms in another position;

Fig. 3 is an end elevational view of the cam employed in my valve-actuating mechanism; and

Fig. 4 is a perspective view of the cam.

To illustrate a preferred embodiment of my invention I haveillustrated in the drawings in a fragmentary view a portion of an engine head 10 having exhaust and intake valve openings 11 and 12, these openings designed to be controlled by the exhaust and intake valves 13 and 14.

The crank shaft of the engine is shown at 15, and in dotted lines. the crank is represented at 16 and the piston at 17.

Rotatably and slidably mounted in supporting frame members 18 and 19 is a cam shaft 20. As shown, the right-hand end of this shaft may be mounted ina sleeve bearing 21 inthe member 18, while the other end of this shaft extends through a bearing "22 in the member 1'9i Upon the extended end of this shaft is a gear 23 and a compression spring 24 acts upon this gear to normally urge the shaft toward the left, as shown in Fig. l.

The cam 25 for actuating the exhaust valve may be of the usual form, but the cam 26 for operating the intake valve is of such form as will be hereinafter described. It will be understood that both of these cams are fixed upon the cam shaft 20 so that they will be moved in the direction longitudinally of the shaft when the latter is moved. It is also understood that there will be a pair of these cams for each of the cylinders with which the engine is provided. The gear 23 is adapted to mesh with a gear 23 upon the crank shaft 15.

As shown in Figs. 3 and 4, the cam 26 is provided with an effective or working surface tapered in width from one end of the cam member to the other, this surface being relatively wide at one end, as shown at 2'7, and relatively narrow at the other end, as shown at 26 these being transverse to the aXis of the shaft Ztl. It will be seen, therefore, that as this shaft is moved to the right, as shown in the drawings, the valve stem 28 (or tappet, if a tappet is provided) will be engaged by a progressively wider portion of the cam, thus holding the valve 14 open during a longer period with respect to the period of rotation of the shaft. As the cam surface is progressively wider from the right-hand end toward the left, as shown in the drawings, the greater the shift of the cam shaft to the right, the longer the valve will be held in open position by the cam.

It may also be noted that, as shown in Figs. 1, 2 and 3, the cam surface of the valve is slightly higher toward its left-hand end 27 than at its right-hand end 26 so that as the cam shaft is moved toward the right, the valve stem will be engaged with a progressively higher portion of the cam and, therefore, will be opened to a Wider extent as well as being held open over a longer period, thus permitting a greater charge to enter the cylinder than would otherwise be the case.

The translatory movement of the shaft 20 is effected by means responsive to the speed of the engine and also responsive to acceleration or pressure in the manifold on the engine side of the throttle valve. The means for effecting movement'of this shaft in response to engine speed will first be described.

A casing 39 may be secured to the frame member 19, and this casing may, if desired, contain oil under atmospheric pressure. Within this casing is a shaft 31 having bearings in the casing walls, the shaft being provided with a gear 32 meshing with the gear 23 so that it will be driven by the latter gear at a speed proportional to the speed of the crank shaft 15. Upon the end of the shaft 31 opposite the gear 32 is a second gear 33 which meshes with a gear 34 upon a stub shaft 35, and secured to this stub shaft is a centrifugal governor of more or less usual form designated by the numeral 36.

This governor comprises weighted members 37 pivoted at 38, each of which has an arm 39 engaging a collar 40 upon a rod 41. Upon the rod 41 is a piston member 42 slidably mounted in a tubular shell 43 extending outwardly from the casing 44 which encloses the governor mechanism. Also secured to the rod 41 is a valve member 45 adapted to control an annular passage or recess 46 in the inner wall of the member 43. A conduit 48 leads from the interior of the tubular member 43 to the left of the valve 45 so as to provide communication between this member and a source of fluid pressure 49 such as oil, for example.

A conduit 50 leads from the passage 46 to the rear end 51 of a cylinder 52; within which is mounted a piston 53. A connecting rod or link 54 is pivoted at 55 to the piston and at 56 to a link 57 which is pivoted intermediate its ends at 58 to a member 59 secured to the shaft 20 and projecting from the end of this shaft.

A link 60 is pivoted at 61 to the cylinder casing and has a slotted pivotal connection 62. with the connecting link 5450 that as the piston 53 moves in the cylinder, the

4 link will be swung about its pivot 61. Pivoted to the upper end of the link 60 is a spring abutment 63 against which acts a compression spring 64, the other end of which acts against the enlarged end 65 of the rod 41 so as to apply pressure upon this rod, urging it toward the left. It will be seen that the amount of pressure applied to the rod by the spring will be determined by the compression of the spring by movement of the link 60.

If it be assumed for the moment that the upper end of the link 57 is fixed, it will be seen that movement of the piston 53 toward the right will move the lower end of the link 57 toward the right and, therefore, move the cam shaft 20 in the same direction. With the above construction it will be obvious when the engine is in operation the position of the governor weights 37 will be determined by centrifugal force due to the speed of the engine. When the weights 37 move outwardly, they will press against the collar 40 and move the rod 41 and valve 45 toward the right. This will uncover the left-hand end of the passage 46 and permit communication between the high pressure source 49 and the end 51 of the cylinder through the conduit 48, passage 46 and conduit 50, which pressure will tend to drive the piston 53 toward the right and thus move the lower end of the lever 57 in that direction. This will also move the cam shaft 20 toward the right so that as the speed of the engine increases, the intake valves will be actuated by a progressively wider portion and also by a progressively higher portion of the cam 26. Thus the valve opening will be increased with the speed of the engine so that it will not act as a throttle to limit this speed.

As the stem 41 is moved toward the right, its movement will be resisted by the spring 64, and the pressure of this spring will be increased in proportion to the movement of the piston 53 toward the right due to the link 60 so that a position of equilibrium will be reached when the valve 46 will again be closed due to pressure of the spring 64, thus cutting off the conduit 43 from the conduit 50. At that point there will be no further move ment of the piston 53 as long as the engine speed re mains constant.

When, however, the engine speed decreases, the governing members 37 will'move inwardly, thus permitting the spring 64 to push the valve 45 to the left which will open the right-hand end of the passage 46 to the interior of the casing 30. As no pressure exists in the casing 30, the oil in the cylinder portion 51 will be permitted to vent or exhaust through the conduit 50 into the casing permitting the piston 53 to move to the left under pressure of the spring 24 until a position of equilibrium has again been reached and the spring 64 is no longer under suflieient pressure to hold the valve 46 in this venting position. Thus it will be seen that as the speed of the engine decreases the cam shaft 20 will be moved toward the left by the spring 24, thus engaging a lower and narrower portion of the cam member 26 with the stems of the intake valves 14.

In order to control the translating movements of the cam shaft 20 by manifold pressure and acceleration or load as well as by engine speed, the upper end of the link 57 is pivoted at 68 to one end of a link 69, the other end of which is pivoted to a piston 70 slidable in a cylinder 71. The wall of the cylinder is provided with an annular recess 72 opening into the cylinder and disposed intermediate the ends of the piston. The piston is provided with a passage 73 which communicates with the recess 72 through an opening 74 and is also provided with a passage 75 adapted to lead from the passage 73 to the interior of the cylinder 71 rearwardly of the piston 70. Communication between the passages 73 and 75 is controlled by a valve 76 mounted upon a valve stem 77, and this valve also controls communication between the passage 75 and an opening 78 leading into the interior of the casing 30.

The valve stern 77 is secured to one end of a collapsible bellows 79 which is mounted in a casing 80 within the casing 30. The interior of the bellows 79 communicates with the atmosphere through a conduit 81, while the interior of the casing 80 around the bellows v79 is in communication with the engine manifold (81 on the engine side of the usual throttle valve by means of a conduit 82.

It will be understood that the bellows is so tensioned or biased that it will normally be urged to some extent to a collapsed position. However, as the pressure in the engine manifold will always be less than atmospheric pressure (existing within the bellows 79), the latter will tend to expand in opposition to its natural bias.

An L-shaped passage 83 provided in the piston 70 opens at one end within the casing 30, and at its other end into the rear end of the passage 73 rearwardly of the enlarged end 84 of the valve stem 77 so that there will be no tendency forpressure to build up in the passage 73 rearwardly of the enlarged end 84.

With this construction it will be seen that as long as the pressure within the engine manifold remains constant, the bellows 79 will be stationary as atmospheric pressure within the bellows will not change perceptibly. However, when the throttle valve of the engine is opened, thus raising pressure within the manifold and admitting a greater charge to the engine to accelerate the same, the increased pressure in the cylinder 80 will tend to collapse the bellows, thus moving the stem 77 and valve 76 toward the right, thus effecting communication between the passage 75 and the annular recess 72. This recess 72 is in constant communication with the source of fluid pressure 49 through a conduit 86 so that fluid under pressure will be admitted into the cylinder 71 rearwardly of the piston through the recess 72, the opening 74 and passages 73 and 75, thus tending to move the piston toward the right. This will move the upper end of the link 57 toward the right and, if the lower end remains fixed, will tend to move the cam shaft 20 toward the right, thus causing the valve stem to be engaged by a wider and higher portion of the cam member 26.

As the piston 70 moves toward the right it will catch up with the valve '76, as the position of the latter will be determined by the amount of collapse of the bellows due to pressure in the casing 80, and communication will be closed between the passages 73 and 75 so that no further movement of the piston will take place, the parts then being in a condition of equilibrium until further change in the pressure existing within the manifold.

if now the pressure in the manifold decreases as it will under less load or when the engine attains constant speed after acceleration, the bellows 79 will tend to open, moving the valve stem 77 toward the left. This will open the communication between the passage 75 and the opening 78, permitting the pressure in the cylinder 71 to vent into the casing 30 through the opening 78 and permitting the piston 70 to move to the left under pressure of the spring 2d, thus moving the shaft 20 toward the left. When the piston 70 has moved a sufiicient distance toward the left, the opening 78 will again be closed by the valve 76 and the piston will then remain in this position of equilibrium. It will be seen, therefore, that with the arrangement described, the valve opening and, therefore, the charge admitted into the cylinders will be controlled not only in response to the speed of the engine but also in response to manifold pressure so that provision will be made not only for vehicle speeds, but also for conditions of acceleration and load.

While I have shown and described a preferred embodiment of my invention, it will be understood that it is not to be limited to all of the details shown, but is capable of modification and variation within the spirit of the invention and within the scope of the claims.

What I claim is:

1. In an internal combustion engine having a cylinder and means including a valve to admit a charge of fuel and air to the cylinder, a cam shaft having a cam secured thereon to actuate the valve to open position, means for mounting said cam shaft for movement in the direction of its axis, said cam having an active surface varying in width longitudinally of the shaft, and means to move said shaft longitudinally of its axis, said means comprising a fluid-pressure-actuated servomotor operatively connected to the shaft, and means controlled by the speed of the engine to supply fluid pressure to said motor.

2. In an internal combustion engine having a cylinder and means including a valve to admit a charge of fuel and air to the cylinder, a cam shaft having a. cam secured thereon to actuate the valve to open position, means for mounting said cam shaft for movement in the direction of its axis, said cam having an active surface varying in width longitudinally of the shaft, and means to move said shaft longitudinally of .its axis, said means comprising a fluid-pressure-actuated servomotor :opera-tively connected to the shaft, a source of fluid pressure, a valve to connect the servomotor to said source and to vent fluid pressure from the servomotor, operating means for said last-named valve, and speed governor means responsive to the speed of the motor connected to said operating means.

3. :In an internal combustion engine having a cylinder and means including a valve to admit a charge of fuel andair to the cylinder, a cam shaft having a cam secured thereon to actuate the valve to open position, means for mounting said cam shaft for movement in the direction of its axis, said cam having an active surface varying in width longitudinally of the shaft, and means to move said shaft longitudinally of its axis, said means comprising a fluid-pressure-actuated servomotor operatively connected to the :shaft, a source of fluid pressure, a valve to connect the servomotor to said source and to vent fluid pressure from the servomotor, operating means for said last-named valve, speed governor means responsive to the speed .of the motor connected to said opera-ting means, and a spring, the force of which is adjusted by movement of said servomotor to oppose movement of said valveoperating means by said governor.

4. In an internal combustion engine having a cylinder and means including a valve to admit a charge of fuel and air to the cylinder, a cam shaft having a cam secured thereon to actuate the valve to open position, means for mounting said cam shaft for movement in the direction of its axis, said cam having an active surface varying in width longitudinally of the shaft, means to move said shaft longitudinally of its axis comprising a fluid-actuated servomotor having a piston connected to said shaft, a source of fluid pressure, a valve to connect the servomotor to said source and to vent fluid pressure from said motor, speed governor means responsive to the speed of the motor for actuating said valve, a spring opposing movement of said valve in one direction, and a lever connected to the piston of said servomotor and acting against said spring whereby the force of the latter is adjusted by movement of the piston of the motor.

5. In an internal combustion engine having a cylinder and means including a valve to admit a charge of fuel and air to the cylinder, said engine having an intake manifold, a cam shaft having a cam secured thereon to actuate the valve to open position, means for mounting said cam shaft for movement in the direction of its axis, said cam having an active surface varying in width longitudinally of the shaft to vary the time the valve is held open during a revolution of the cam shaft, and means responsive to pressure existing in the manifold for moving said shaft longitudinally of its axis to vary the point of engagement of the cam.

6. In an internal combustion engine having a cylinder and means including a valve to admit a charge of fuel and air to the cylinder, said engine having an intake manifold, a cam shaft having a cam secured thereon to actuate the valve to open posit-ion, means for mounting said cam shaft for movement in the direction of its axis, said cam having an active surface varying in width longitudinally of the shaft to vary the time the valve is held open during a revolution of the cam shaft, and means to move said shaft longitudinally of its axis, said means comprising a fluid-pressure-actuated servomotor having a piston operatively connected to the shaft, and means controlled by pressure existing in the engine manifold to supply fluid pressure to said servomotor.

7. In an internal combustion engine having a cylinder and means including a valve to admit a charge of fuel and air to the cylinder, a cam shaft having a cam secured thereon to actuate the valve to open position, means for mounting said cam shaft for movement in the direction of its axis, said cam having an active surface varying in width longitudinally of the shaft to vary the time the valve is held open during a revolution of the cam shaft, means to move said shaft longitudinally of its axis, said means comprising a servomotor having a piston operatively connected to the shaft, a source of fluid pressure, a valve to connect the servomotor to said source and to vent pressure from said motor, and means for actuating said last-named valve in response to changes of pressure in the engine manifold.

8. In an internal combustion engine having a cylinder and means including a valve to admit a charge of fuel and air to the cylinder, a cam shaft having a cam thereon to actuate the valve to open position, means for mounting said cam shaft for movement in the direction of its axis, said cam having an active surface varying in Width longitudinally of the shaft, said engine having an intake manifold, and means responsive both to the speed of the engine and to pressure existing within said manifold for moving said shaft longitudinally of its axis to vary the point of engagement of the cam.

9. In an internal combustion engine having a cylinder, a fuel manifold, and means including a valve to admit a charge of fuel and air to the cylinder, a cam shaft having a cam thereon to actuate the valve to open position, means for mounting said cam shaft for movement in the direction of its axis, said cam having an active surface varying in width longitudinally of the shaft, means responsive to pressure in the manifold for moving said shaft longitudinally of its axis to vary the point of engagement of the cam, said last-named means comprising a servomotor operatively connected to the shaft, 2. source of fluid l 8 V pressure, a valve to connect the servomotor to said source and to ventpressure fluid therefrom, operating means for said last-named valve, and meansto actuate said valveoperating means comprising a movable member connected to the valve and exposed upon one side to pressure in the engine manifold and upon the other side to atmospheric pressure.

10. In an internal combustion engine having a cylinder, a manifold and means including a valve to admit a charge of fuel and air to the cylinder from the manifold, means to actuate said valve including a rotatable cam shaft and a cam on said shaft having an active surface varying in Width longitudinally of the shaft, said shaft being mounted for movement inthe direction of its axis, a spring acting upon said shaft to move it in one direction, an element connected to said shaft to move it in the opposite direction, and means responsive to the speed of the engine and to pressure existing within the engine manifold to move said element.

11. In an internal combustion engine having a cylinder, a manifold and means including a valve to admit a charge of fuel and air to the cylinder from the manifold, means to actuate said valve including a rotatable cam shaft and a cam on said shaft having an active surface varying in width longitudinally of the shaft, said shaft being mounted for movement in the direction of its axis, a spring acting upon said shaft to move it in one direction, an element connected to said shaft to move it in the opposite direction, a pair of fluid-pressure servomotors connected to said element to actuate the same, means responsive to the speed of the engine to introduce fluid pressure to one of said motors, and means responsive to manifold pressure to introduce fluid pressure into the other of said motors.

References Cited in the file of this patent UNITED STATES PATENTS 1,687,082 Cole Oct. 9, 1928 .l,863,875 Rabezzana June 21, 1932 2,191,459 Duncan Feb. 27, 1940 2,528,983 Weiss Nov. 7, 1950 2,670,595 Miller Mar. 2, 1954 FOREIGN PATENTS 406,280 Germany Nov. 17, 1924 676,020 France Feb. 18, 1930

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