US2620821A

US2620821A - Speed governor

Info

Publication number: US2620821A
Application number: US741169A
Authority: US
Inventors: William E Leibing
Original assignee: Individual
Current assignee: Individual
Priority date: 1947-04-14
Filing date: 1947-04-14
Publication date: 1952-12-09
Anticipated expiration: 1969-12-09

Description

De- 9, 1952 w. E. LEIBING 2,629,821

SPEED 'GOVERNOR Filed April 14, 1947 3 Sheets-Sheet l attorneys.

w. E. LEIBING SPEED GovERN'oP.

Dec. 9, 1952 Filed April 14, 1947 3 Sheets-Sheet 2 Mam/vf.' H5/N6,

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DEC- 9, 1952 w. E. LEIBING 2,620,821

sPEoGovERNoR Filed April 14. 194'? 3 Sheets-Sheet 3 a l Jfz .3.

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Patented Dec. 9, 1952 UITED STATES @A'i' Claims.

This invention relates to speed governors for internal combustion engines and is directed to improvements for controlling the position of the throttle valve for limiting the maximum speed of the engine.

The principal object of this invention is to provide an improved form of speed governor for an internal combustion engine which acts to maintain within close limits a preselected maximum engine speed irrespective of the load imposed upon the engine.

Another object is to provide an improved form of engine speed governor which is economical to manufacture and which employs only a standard form of spring of conventional design and yet which is capable of governing the maximum engine speed within close limits.

Another object is to provide such a governor in which the maximum engine speed may be selected as desired, without changing springs.

Another object is to provide a speed governor in which friction lag is substantially overcome by opposed diaphragme, one connected directly to a source of vacuum pressure and the other connected through a valve controlled oriiice to a source of variable vacuum pressure which varies in accordance with the position of the throttle valve.

Another object is to provide a governor of this type which employs check valves to protect the diaphragms against rupture in the event of backre downstream from the throttle valve.

A further object is to provide an engine speed governor which overcomes the tendency of prior art governors to lock up during a period of deceleration when the engine is being driven from the momentum of its normally driven load.

Other objects and advantages will appear hereinafter.

In the drawings:

Figure 1 is a top plan view of a speed governor for an internal combustion engine and illustrating a preferred embodiment of my invention.

Figure 2 is a sectional elevation taken substantially on the lines 2 2 as shown in Figure 1.

Figure 3 is a sectional elevation taken substantially on the lines 3 3 as shown in Figure 1.

Figure 4 is a sectional elevation taken substantially on the lines li-i as shown in Figure 2.

Figure 5 is a sectional plan View taken on line 5 5 as shown in Figure 3, and illustrating on an enlarged scale a plug element employed in connection with my invention.

Figure 6 is a schematic sectional View illustrating the action of a preferred form of diaphragm with respect to its enclosure.

Figure 7 is a graph illustrating a typical relationship between angular position of the throttle valve with relation to the vacuum pressure in the engine manifold, the engine speed remaining constant.

Figure 8 is a graph illustrating a typical relationship between engine R. P. M. and ft.lbs. of torque output and illustrating the action of a governor embodying my invention in controlling the maximum engine speed at any one of a plurality of preselected speeds.

Referring to the drawings, the graph shown in Figure 7 includes curve A which represents a relatively high governed speed, for example, 3,000 R. P. M. and the curve B` represents a relatively low governed speed, for example, 1,200 R. P. M.

Considering first curve A, when the throttle valve of the engine is fully open and the load on the engine is suiilciently great to limit the speed to 3,000 R. P. M., the vacuum pressure in the engine manifold is about 3 inches of mercury. As the load on the engine is decreased, the throttle valve must be turned toward closed position in order to maintain the engine speed constant, and, therefore, when the throttle has turned approximately degrees from open position, the Vacuum pressure in the manifold is increased to almost G inches of mercury. Similarly, as the load is released from the engine and the throttle valve turned further toward closed position in order to maintain the engine speed constant, manifold vacuum pressure would reach about l1 inches of mercury when the throttle valve had been rotated about degrees, and when the entire load has been released the vacuum pressure would reach about 16 inches of mercury and the throttle valve would have been rotated about 72 degrees.

. Curve B represents the vacuum curve of the same governor when set at a lower speed, for example, 1,200 R. P. M. With full engine load and wipe open throttle, the manifold vacuum pressure would be less than one-half inch of mercury. As the load is released and the throttle valve turned to maintain the engine speed constant, the manifold vacuum pressure would reach about 4 inches of mercury after 35 degrees of rotation of the valve and would reach about 19 inches of mercury when the valve had rotated 77 degrees and the load on the engine completely released.

The purpose of the engine speed governor is to control the angular movement of the throttle valve exactly as shown by curves A and B depending on the vacuum pressures existing in the engine manifold. If this is done, the engine will maintain a substantially constant maximum speed regardless of a varying load.

In order to limit the maximum opening of the throttle and thus limit the maximum engine speed, the manifold vacuum is applied to a diaphragm or piston, but in such event a force opposing the movement of the piston must be applied. This force must be a varying one and therefore the straight line characteristics of a tension or compression spring are not suitable. In other words, the curves A and B are not straight lines, and, therefore, a particular spring which is sufficiently weak to approximate the lower ends of the curves A and B near the open position of the throttle are entirely too weak for the intermediate and final ranges of the curves toward the closed position of the throttle. In prior art governors, attempts have been made to provide springs which have a varying spring rate to correspond with the shape of the curves A and B, but the difficulty of providing such springs in practice and of adjusting the springs for different governed speeds has resulted yin constructions which were held too costly or too delicate for the intended service. From this discussion it will be understood that a highly desirable feature cf my invention is the provision of a governor which will automatically position the throttle valve at the correct angular position in response to increasing vacuum pressure in the manifold so that the maximum engine speed is maintained substantially constant.

The'structure which I provide for accomplishing the purposes set out above includes a carburetor barrel I having an upper flange II for attachment to the flange of a carburetor of the down draft type (not shown), and the lower fiange I-2 for attachment to the engine intake manifold (not shown). lThe barrel I9 is provided with a central bore or fiow passage I3 in which is mounted a conventional form of throttle valve assembly generally designated I4. This assembly includes a pivot shaft I5 rotatably supported in bearings IS extending across the barrel and having a throttle disk valve Il fixed thereto. A clutch mechanism I8 providing an angular lostmotion connection connects one end of the pivot shaft I5v with the actuating stub shaft I9. An actuator crank 20 is fixed to the stub shaft I9 by means of the nut QI, and an arm 22 fixed to the barrel IB prevents disengagement of the clutchV mechanism I8. A crank 23 fixed on the other end of the pivot shaft I5 is pivotally connected to a control bar 24 by means of the pivot pin 25. The arrangement of parts so far described is such that angular movement of the control crank 29 serves to turn the pivot shaft I5 and throttle disk I'I within the fiow passage I3 and transverse movement of the control bar 24 effects the same result.

The control bar 24 is mounted within a case 26 attached to the barrel I0 as by screws 26a and provided with a cover 2'! attached by means of the screw elements 28. At one end of the case is the primary diaphragm housing 22 which includes the bell portion 30 on the case 26 and the cooperating extension 3l. A fiexible annular diaphragm 32 is clamped in position between the bell 30 and extension 3l by means of the screw fasteners 33 and defines a primary diaphragm chamber 34 within the extension 3I. A pair of non-resilient washer elements 35 are mounted centrally on opposite sides of the diaphragm 32 and provide the means by which Inotion of the diaphragm is transmitted to the control bar 24. A cleVis 36 is attached to the washers 35 and is pivotally connected to the control bar 24. Clevis 33 extends through the washers 35 and is provided with a head portion 35 which acts as a guide to receive one end of the compression spring 3'1. The other end of this spring is carried on the fitting 38 which is adjustably positioned with respect to the extension 3| by means of the adjusting screw 39 and the lock nut 4G.

A passageway 4I is formed in the case 26 and communicates at one end 42 with the flow passage I3 at a point below the throttle valve assembly I4, and communicates at the other end with the interior of the extension 3i by way of the check valve 43 and passageway 44. A spring 45 normally maintains the valve 43 in closed position against a valve seat 46. From the above description, it will be understood that vacuum pressure existing within the flow passage I3 below the throttle valve assembly I4 is connected to the primary vacuum chamber 34 by way of the opening passage 4I, check valve 43 and passage 44.

The diaphragm 32 is provided with an annular rib 4'! which is adapted to contact a generated surface or surface of revolution 43 provided within the extension 3I and adjacent the outer part of the movable portion of the diaphragm 32. Reference to Figure 6 shows the effect of the cooperation between the rib 41 and the surface 43 in reducing the effective area of the diaphragm within the chamber 34 as the central portion of the diaphragm moves toward the chamber. The three positions shown schematically in Figure 6 illustrate the diaphragm in its fully effective position A, an intermediate position B in which its effective area has been substantially reduced by contact between the rib and the generated surface, and the position C in which the effective area of the diaphragm has been reduced to a minimum. A feature of this construction is that as the vacuum pressure within the chamber 34 increases, that is to say, as the absolute pressure decreases, the atmospheric pressure on the exposed side of the diaphragm within the space 49 moves the washers 36 toward the right, as viewed in Figures 2 and 6, but the extent of movement falls off with increasing vacuum pressure rather than moving as a straight line function, assuming the spring 3l to have a constant spring rate.

At the end of the case 26 opposite from the bell portion 39, an enlargement 5B is provided and a cap 5I is adapted to cooperate with the enlargement to clamp the secondary diaphragm 52 therebetween. The cap 5I is held in position by means of the screw elements 53. Central non-resilient washers 54 connect the central portion of the diaphragm with a link 24h which, in turn, engages the longitudinal slot 24a in the control bar 24. The secondary chamber 55 defined between the iiexible diaphragm 52 and the cap 5I is connected to a variable source of vacuum pressure which will now be described.

A plug element 55 is mounted in the wall of the barrel IZ! and provided with a port 5T of any preferred or desirable shape or design. As shown in the drawings, this port is formed as a slot in the plug 56 extending in a direction parallel to the direction of fiow through the passage I3. It is recognized that this port may take any one of several different shapes or designs, and the slot 51 is shown for illustrative purposes only. A passage 58 in the plug 56 communicates with a metering orice 59 which connects with the passage 60. Passage 60 extends into the case 26 to the check Valve 6I which is held against its seat 52 by means of the spring 63. The check valve 6l is in communication with the secondary chamber 55 by Way of the passage 54. An opening 65 is provided in the wall of the barrel I0 at a point upstream from the location of the port 51 and upstream from the closed position of the throttle valve disk I1. The opening 65 communicates with the passage 60 and an adjustable needle valve 65 is provided to restrict this communication. The position of the slot 51 is such that the edge 31 of the throttle valve disk I1 passes closely adjacent thereto when it moves from its closed position toward open position.

It will be understood that the pressure within the flow passage I3 above the throttle disk I1 is substantially atmospheric pressure, whereas the pressure existing within the iiow passage I3 below the throttle disk I1 corresponds to the vacuum pressure in the inlet manifold. Accordingly, as the edge 51 of the disk moves about its Divot shaft axis toward opening position, the upper end of the slot 51 is gradually exposed to atmospheric pressure and the further the disk I1 pivots toward open position, the greater proportion of the length of the slot 51 is subjected to atmospheric pressure rather than vacuum pressure in the inlet manifold.

A small vent passage is provided for each of the

vacuum pressure chambers

34 and 55 in order to permit absolute pressure to build up in the chambers when the vacuum pressure transmitted through the inlet passageways 44 and 64, respectively, falls oi. As shown in the drawings, such Vent openings may be positioned in the diaphragm assembly and may take the form of a small drilled hole 68 extending through the washers 35 and diaphragm 32.

In a similar manner, a bleed port 69 may be provided in the washers 54 and diaphragm 52 to enable the chamber 55 to return toward atmospheric pressure when the check valve 6| is closed. If desired, this bleed port 69 may be formed by drilling a small hole, for example, 0.040 inch in diameter and then placing a wire of 0.038 inch diameter in the hole. The leakage occurring through this bleed port 69 is therefore so small that it has substantially no effect when the inlet passageway 44 is subjected to vacuum pressure, but will permit the absolute pressure within the chamber 34 to build up by leakage from the atmosphere when the check valve 43 is closed.

The check valve 43 acts to protect the diaphragm 32 against rupture should an explosion occur within the flow pasage I3 and the rather heavy pressure therefrom be transmitted through the passageways 4I and 34. The explosion pressure due to this spit-back is thus prevented from damaging the iiexible diaphragm 32. The check valve El protect-s the diaphragm 52 in the same manner, but, in addition, serves another very important function as Will be understood from the following detailed description of the operation of this device.

Assuming that the engine on which the barrel I0 is mounted is driving a loaded truck along a level highway with the engine turning at full governed speed, for example, 3,000 R. P. M. Assuming that the truck begins to climb a hill, the initial position of the throttle disk I1 may be adjacent its fully closed position with the edge 61 near the upper end of the slot 51. Under such conditions, the vacuum pressure existing in the fiow passage I3 below the throttle valve assembly I4 is relatively high, and may correspond to the point X, shown on curve A in Figure 7, and may amount to about 15 inches of mercury, the throttle valve being positioned degrees from full open position.

As the truck begins to climb the hill, a slight additional load is applied to the engine and it immediately tends to slow down, and, hence, the vacuum pressure in the manifold falls oil' to a lower gure, for example, 141A inches. The vacuum pressure within the primary vacuum chamber 34 also falls to |41@ inches. If the secondary vacuum chamber 55 were also in direct connection with the engine manifold, the vacuum pressure would also fall olfI in this chamber, but, immediately, the absolute pressure is higher on the right hand side of the ball check 6|, as shown in Figure 2. It closes and retains momentarily the vacuum pressure within the chamber 55 that it formerly had. If the vacuum chamber 55 were fully sealed and the ball check 6I fully closed, the vacuum pressure within the chamber 55 could never be dispersed once it had been created, but the very slow leak through the bleed port 69 allows atmospheric air to enter the chamber 55 so that after a very short interval of time the chamber 55 again reflects the vacuum pressure existing on the right hand side of the ball check 6I. Accordingly, as the engine first begins to slow down as the truck begins to climb the hill, there would be a vacuum pressure of about 141/4 inches of mercury in the manifold and in the primary vacuum pressure chamber 34, but, momentarily, there would still be the same vacuum pressure in the chamber 55 that had existed when the truck was operating on the level highway.

At this moment, there are two forces acting to open the throttle valve disk I1, the spring 31 and the vacuum pressure in the chamber 55. These forces are opposed by the vacuum pressure in the chamber 34 acting on the diaphragm 32, but since the latter vacuum pressure has decreased slightly, the assembly including the

washers

35 and 54 and the link 24h and control member 24 move toward the left, as viewed in Figure 2, thereby turning the throttle valve disk I1 in a counterclockwise direction toward open position. A succession of such cycles occurs as the grade increases, and as additional load is applied to the engine. In each of these cycles, the throttle valve disk moves toward open position further until the lower edge 61 of the disk I1 passes below the lower edge of the slot 51 at which point the action of the vacuum chamber 55 ceases. 'Ihe link 24h then moves within the slot 22a and no longer contributes toward movement of the control member 24 toward the left, as viewed in Figure 2.

During the loading of the engine so far described, the manifold vacuum pressure has decreased along the curve A, as shown in Figure '1, until it reaches a point, for example, where the throttle valve angular position corresponds to 50 degrees. At this point, the diaphragm 32 is still in the position coresponding to C, as shown in Figure 6, and as the vacuum pressure within the primary vacuum chamber 34 continues to fall, the diaphragm 32 moves from the position C toward the position B thereby increasing its effective area by reason of the cooperation between the annular rib 32 and the generated surface 53.

Accordingly, the rate of change of force acting on the control member 2d is in a straight line function with the absolute pressure existing in the chamber 34 since the eifective area of the diaphragm 32 varies with the movement of the member 2. As the load on the engine continues to increase, the vacuum pressure within the chamber 34 continues to decrease and the diaphragm 32 moves from the position B, shown in Figure 6, toward the fully extended position A, at which time the full area of the diaphragm 32 is effective. This position A may correspond to an angular position of the throttle disk l1 of about degrees, as shown in the chart in Figure 7. Further loading of the engine decreases the vacuum pressure in the manifold still further, but the action of the governor is now a straight line function with the vacuum pressure since only the spring 3l opposes the vacuum pressure within the chamber 34. As explained above, the spring 3l has a constant spring rate.

To summarize, the action of the governor as the engine load increases with the engine operating at full governed speed occurs in three steps. The first includes the operation of the secondary vacuum pressure chamber in assisting the spring 3'! to oppose movement of the diaphragm 32. rlhe second phase comes into play with the cooperation of the rib 41 and generated surface A8 in changing the effective area of the diaphragm 32. The third phase utilizes only the straight line resistance of the compression spring 3?.

The effect of the action of this governor upon the engine speed may be demonstrated by reference to Figure 8. Assuming the truck to be traveling on a level highway and accelerating toward full governed speed, and assuming that the governor is set for 1,200 R. P. M. the throttle lever, not shown, is moved to full position by the truck operator and the engine speed increases toward 1,200 R. P. M. When the speed reaches about 1,150 R. P. M., the manifold vacuum pressure builds up to the point where the diaphragm S2 moves against the action of the compression spring 37 and moves the throttle disk I1 and toward closed position. The lost motion connection provided by the clutch I8 thus allows the governor to close the throttle valve assembly lll even though the throttle lever, not

shown, remains at its fully advanced position.

As the engine speed continues to increase, the ft.-lbs. of torque output drops ofi rapidly along the solid line A because the throttle valve is being moved towards closed position. When the load on the engine is reapplied, the dashed line A represents the relationship between engine R. P. M. and ft.-lbs. of torque delivered. If the governor could be made absolutely frictionless, the loading and unloading lines would be exact duplicates. Whenever the load is being released, the conditions along the solid will be attained, but when the load is rst released a little and then immediately reapplied the hesitation of moving from one line to another always appears.

Accordingly, it will be understood that if the action of the governor can aways occur too far in one direction so that it must always recover in the other direction, we may attain a substantially frictionless governor insofar as its operation is concerned. The importance of the auxiliary vacuum chamber 55 together with its ball check El and the resulting delayed action is therefore readily appreciated. Thus, the governor is always allowed to position itself on the solid line, for whenever a load is applied to the engine, the preponderance of forces acting to open the throttle valve assembly a little too far and the immediate recovery from this condition again takes place on the solid line.

The curves B and C represent similar action of the governor when set for governed speeds of 2,000 and 3,000 R. P. M. respectively.

It will be noted that the diaphragm 52 is considerably smaller in diameter than the diaphragm 32 and is therefore not capable of the same amount of motion but rather about one-half of said motion. Accordingly, the slot 24a is provided near the end of the bar 24 to allow the bar 24 to move throughout the full range provided by the diaphragm 32.

Adjustment provided by the needle valve 6B is important since, in connection with the adjusting screw S for the spring 37, it enables the governor to be set for any desired governed speed of the engine. These relatively simple and accessible adjusting members may be turned to set the governor to hold the engine speed at any desired maximum, such as, for example, 1,200 R. P. M., 2,000 R. P. M., or 3,000 R. P. M., and the same spring 3! may be used for all three governed speeds.

A peculiar condition has been observed during eceleration, at which time the truck is driving the engine and under which condition the vacuum pressure in the flow passage I3 may sometimes rise as high as 26 inches of mercury causing some governors to lock the throttle valve assembly I4 in fully closed position and making it practically impossible to open the throttle valve assembly I4 until speeds far below the desired governed speed have been reached. No such difficulty is present in the construction embodying my invention since the secondary vacuum chamber 55 is exposed to the vacuum pressure within the manifold. The major portion of the slot 51 is exposed to the high vacuum pressure, and hence the control member 24 is moved toward the left, as viewed in Figure 2, and hence no tendency whatever exists to lock up even against vacuum pressures as high as 26 inches of mercury.

Having fully described my invention, it is to be understood that I do not wish to be limited to the details herein set forth, but my invention is of the full scope of the appended claims.

I claim:

1. In a speed governor for an internal combustion engine, the combination of a throttle valve assembly for controlling flow of combustible mixture through a flow passage, said assembly including a throttle valve disk pivotally mounted within the fiow passage, vacuum pressure responsive means, said means including a pair of opposed vacuum pressure chambers each having a movable element operatively associated with the throttle valve disk and adapted to limit the extent of pivotal movement thereof, port means in the v/all of the flow passage adjacent an edge of the disk when in fully closed position and downstream therefrom, means providing a passageway between the port means and one of said pressure chambers, and passage means connecting the other pressure chamber' with the dow passage downstream from the throttle valve assembly.

2. In a speed governor for an internal combustion engine, the combination of a throttle valve assembly for controlling flow of combustible mixture through a ow passage, said assembly including a throttle valve disk pivotally mounted within the flow passage, vacuum pressure responsive means including opposed flexible diaphragms operatively associated with the throttle valve disk and adapted to limit the extent of pivotal movement thereof, port means in the wall of the flow passage adjacent an edge of the disk when in fully closed position and downstream therefrom. means providing a passageway between the port means and one of said flexible diaphragms, and passage means connecting the other flexible diaphragm with the flow passage downstream from the throttle valve assembly.

3. In a speed governor for an internal combustion engine, the combination of a throttle valve assembly for controlling flow of combustible mixture through a flow passage, said assembly including a throttle valve disk pivotally mounted within the flow passage, vacuum pressure responsive means, said means including a pair of opposed vacuum pressure chambers each having a diaphragm operatively associated with the throttle valve disk and] adapted to limit th-e extent of pivotal movement thereof, port means in the wall of the flow passage adjacent an edge of the disk when in fully closed position and downstream therefrom, means providing a first passageway between the port means and one of said flexible diaphragms, means providing a second passageway connecting the other flexible diaphragm with the flow passage downstream from the throttle valve assembly, a check valve in each passageway, and a restricted opening associated with each vacuum pressure chamber acting tobleed each respective chamber to atmosphere.

4. In a vacuum responsive speed governor for an internal combustion engine having a throttle Valve disk pivotally mounted within a flow passage for combustible mixture; the combination thereof: vacuum pressure responsive means including a pair of opposed vacuum pressure chambers each provided with a movable element, said elements being operatively associated with the throttle valve disk and adapted to limit the extent of pivotal movement thereof, resilient means associated with one of said vacuum pressure chambers adapted to oppose movement of its respective element, port means in the wall of the ow passage adjacent an edge of the disk when in fully closed position and down stream therefrom, means providing a passageway between the port means and the other of said pressure chambers, a check valve in said passageway, and a restricted opening associated with each va-cuum chamber acting to bleed each respective chamber to atmosphere.

5. In a vacuum responsive speed governor for an internal combustion engine having a throttle valve disk pivotally mounted within a flow passage for combustible mixture; the combination thereof: vacuum pressure responsive means, said means including a primary vacuum chamber and a secondary vacuum chamber acting in opposition thereto, a movable element associated with each of said chambers adapted to limit the extent of pivotal movement of the throttle valve disk, means forming a passageway connecting the primary vacuum chamber with the flow passage down stream from the throttle valve assembly, port means in the wall of the flow passage adljacent the edge of the disk when in fully closed position and down stream therefrom, passage means adapted to establish communication between the port means and the secondary vacuum chamber whereby the force exerted by the element associated with the secondary vacuum chamber increases as the throttle valve disk approaches its closed position, and a check valve associated with said passage means.

WILLIAM E. LE'IBING.

REFERENCES CITED The following references are of record in the le of this patent:

UNITED STATES PATENTS Number Name Date 945,992 Stevens Jan. 11, 1910 1,579,536 Hodgson Apr. 6, 1926 1,944,638 Englestrom et al. Jan. 23, 1934 2,196,498 Jennings Apr. 9, 1940 2,269,496 Vanderpoel et al. Jan. 13, 1942 2,408,161 Darnell Sept. 24, 1946 2,409,070 Ruby Oct. 8, 1946 2,424,836 Mallory July 29, 1947 2,482,291 Rush Sept. 20, 1949 2,514,388 Gilmore July 11, 1950 FOREIGN PATENTS Number Country Date 21,363 Great Britain Oct. 20, 1905