GB2028425A

GB2028425A - Speed Control Governor for Regulating the Maximum Speed of Internal-Combustion Vehicle Engines

Info

Publication number: GB2028425A
Application number: GB7929399A
Authority: GB
Original assignee: Groeneveld Transport Efficiency BV
Current assignee: Groeneveld Transport Efficiency BV
Priority date: 1978-08-23
Filing date: 1979-08-23
Publication date: 1980-03-05
Also published as: FR2434270A1; DE2933567A1; IT1121467B; JPS5532991A; NL7808685A; IT7968706A0; SE7906987L

Abstract

A speed control governor for regulating the maximum speed of internal-combustion vehicle engines controlled by a fuel-supply pump (1) having a fuel-supply regulating lever (3), a linkage system (7, 8, 9,) connecting said regulating lever with a vehicle accelerator pedal (10), and an end stop (5) for limiting the maximum travel of said regulating lever when the accelerator pedal is fully depressed. The governor comprises adjusting means (8) for resetting said maximum travel of said regulating lever between a higher and a lower end position of said lever and thus between a higher and a lower limit value of the engine speed, respectively, and means (44) for automatically controlling the actuation of said adjusting means in response to a selected travelling speed of the vehicle. The governor also includes retarding means (28) operatively cooperating with said adjusting means for slowing down said resetting operation of the adjusting means on the actuation thereof. <IMAGE>

Description

SPECIFICATION Speed Control Governor for Regulating the Maximum Speed of Internal-combustion Vehicle Engines The invention relates to a speed control governor for regulating the maximum speed of internal-combustion vehicle engines, particularly diesel engines for heavy goods vehicles or the like. Such engines are conventionally controlled by a fuel-supply pump having a fuel-supply regulating lever, a linkage system connecting this regulating lever with a vehicle accelerator pedal, and an end stop for limiting the maximum travel of the regulating lever when the accelerator pedal is fully depressed. This end stop thus defines the angular end position of the regulating lever of the fuel-supply pump corresponding to maximum engine speed.

In general, diesel engines of heavy goods vehicles or the like have a predetermined maximum speed which can be adjusted to the value desired for any particular engine by adjusting the maximum end stop for the regulating lever of the fuel pump. This maximum speed can thus be selected so that in the lower gears with the throttle wide open the engine can produce sufficient power to enable the vehicle to be accelerated as much as possible without damaging the engine.If however, when travelling on motorways or the like, the driver fully depresses the accelerator pedal in top gear so 'that for prolonged periods the engine rotates at the maximum engine speed of, for example, 2500 r.p.m., this may lead to increased wear and, under certain circumstances, to serious damage to the engine, quite apart from the fact that driving, when fully laden, at maximum speed is dangerous and entails an uneconomical fuel consumption. It is therefore highly desirable to provide means for limiting the maximum driving speed of the vehicle to a value corresponding to a lower value of the maximum engine speed of, for example, 2200 r.pm. without, however, at the same time lowering the acceleration power at lower driving speeds.

The Netherlands patent application 76.04709 discloses a speed control governor for this purpose which comprises adjusting means for resetting the maximum travel of the regulating lever of the fuel-supply pump between a higher and a lower end position of the lever and thus between a higher and a lower limit value of the engine speed respectively, and means for automatically controlling the actuation of the adjusting means in response to a selected travelling speed of the vehicle. Thus, when the vehicle speed increases and reaches said selected speed, the control means, comprising for example a tachometer, actuates the adjusting means which resets the maximum possible travel of the fuel pump regulating lever from the higher to the lower end position of this lever whereby also the maximum engine speed is limited to a lower value.On the other hand, at vehicle speeds below said selected speed, when the tachometer or other control means has not yet actuated the maximum speed adjusting means, the fuel pump regulating lever can be moved to its higher end position so that the full engine power is available during the acceleration of the vehicle.

Although this known maximum speed governor has shown to function satisfactorily, it is still susceptible of improvement. It has appeared that, when the adjusting means is actuated by the tachometer or other suitable impulse generating means, the fuel pump regulating lever is moved rather abruptly which causes a perceptibie shock in the vehicle, particularly if the regulating lever is moved to increase the fuel supply and thus the engine power. This phenomenon is furthermore particularly annoying when the vehicle is driven with small speed variations in the range of the selected travelling speed to which the control means responds since in that case the adjusting means is repeatedly actuated in the one and the other sense.

It is accordingly an object of the present invention to provide a speed control governor of the kind described which obviates this disadvantage.

An other object of the invention is to provide such a speed control governor which is of simple construction and which can be easily mounted on existing vehicle engines of various type.

According to the invention, the speed control governor comprises retarding means operatively cooperating with the maximum speed adjusting means for slowing down the resetting operation of the adjusting means up on actuation thereof.

The retarding means thus prevents a sudden resetting of the regulating lever when the adjusting means is actuated whereby shocks caused by an abrupt acceleration or decelleration of the vehicle are avoided.

As disclosed in the above-mentioned Netherlands patent application 76.04709, the maximum speed adjusting means may advantageously include a cylinder, a piston, slidable in this cylinder, return spring means acting on said piston in one direction, said cylinder, piston and spring means being incorporated in said linkage system, a fluidpressure source, a fluid-control valve operable by said automatic control means to connect said cylinder alternatively to said source and the atmosphere, respectively, to thereby cause said piston to move against said spring means to a first end position in said cylinder corresponding to a minimum effective length of said linkage system or, by the action of said spring means, to a second end position in said cylinder corresponding to a maximum effective length of said linkage system, respectively, whereby, when the accelerator is fully depressed, in said first piston end position the fuel pump regulating lever occupies said higher lever end position and in said second piston end position said regulating lever occupies said lower lever end position. According to a preferred embodiment of the invention, in a governor of this type the retarding means is arranged between said piston and said return spring means, said retarding means comprising a first and a second liquid-filled chamber, a partition member separating said two chambers, a throttling channel formed in said partition member connecting adjacent ends of said two chambers and allowing restricted liquid flow between said chambers, said piston having a part movable in said first chamber, and auxiliary piston means movable in said second chamber in opposition to said piston part in said first chamber, said return spring means acting on said auxiliary piston means.In this manner a very compact arrangement is obtained allowing the governor to be easily installed and to replace the conventional accelerator pedal rod of the linkage system between the accelerator pedal and the fuel pump regulating lever of existing motor vehicles.

Preferably, a throttle regulating valve is provided in the throttling channel for adjusting the passage of this channel. In a preferred embodiment, two separate, independently adjustable regulating valves are arranged in series in the throttling passage, each of these two regulating valves having a by-pass and check valve in this by pass, the two check valves of the two regulating valves operating in opposite directions of liquid flow. The time interval needed for fully resetting the adjusting means from the lower to the higher limit value of the engine speed can thus be regulated separately from the time interval for resetting from the higher to the lower speed limit value.

Further particulars and advantages of the invention will appear from the following description with reference to the accompanying drawings showing a preferred embodiment of the invention.

In the accompanying drawings: Fig. 1 is a vertical longitudinal section of a speed control governor according to the present invention, wherein the pneumatic and electric control system is diagrammatically illustrated and the parts of the governor are in the relative position allowing maximum travel of the fuel pump regulating lever; Fig. 1A shows, on an enlarged scale, a section of the retarding means; and Fig. 2 is a longitudinal section, similar to fig. 1, but showing the parts positioned for limited maximum engine speed.

Referring to Figs. 1 and 2 of the drawings, there is shown with dotted lines the contour of a conventional fuel-supply pump 1 of a diesel engine (not shown) of a motor vehicle, particularly a heavy goods vehicle. The pump 1 has an outwardly extending regulating spindle 2 and a fuel-supply regulating lever 3 secured to this spindle 2 in a conventional manner. The regulating lever 3 carries an abutment member 4 adapted to cooperate with a set screw 5 forming an upper limit stop for the regulating lever 3 which is generally adjusted and sealed by the manufacturer of the pump. The pump further has the usual lower limit stop 6 for the regulating lever 3.

The regulating lever 3 is coupled by a linkage system with the accelerator pedal 10 of the vehicle which system comprises a longitudinally extending maximum speed adjusting device 8 pivotally connected to the end of the lever 3, a rod 7 fixedly secured to the device 8 and extending coaxially therefrom, and a supporting arm 9 pivotally connected to the outer end of the rod 7 and to the engine chassis 11. The arm 9 is coupled to the accelerator pedal 10 in a conventional manner such that when the pedal 10 is depressed, the rod 7 is moved to the left, as seen in figs. 1 and 2 and the regulating lever 3 is rotated in the direction of increasing the fuel supply.The rod 7 and the adjusting device 8 together form a unit which replaces the conventional accelerator pedal rod directly connecting the lever 3 with the arm 9 and this unit has, in the situation shown in fig. 1, the same effective length as the conventional rod it replaces. A support 12 is mounted on the engine chassis 11 and carries an adjustable and, in its adjusted position, sealed set screw or end stop 13 for the arm 9. This end stop 13 determines the position of maximum travel of the rod 7 when the accelerator pedal 10 is fully depressed.

The adjusting device 8 comprises an elongate tubular cylindrical housing 14 having at one end an end block 1 5 secured therein, this end block comprising a threaded bore receiving the threaded end of the rod 7 in a manner to allow the effective length of this rod to be adjusted. A ring member 1 7 is secured in the opposite end of the housing 14 which ring member has a threaded bore adjustably receiving a hollow tubular set screw 1 8 projecting inwardly into the housing and adapted to be sealed in its adjusted position.

A piston 19 with piston rod 20 is axially slidably and sealingly arranged in the cylindrical housing 14, the piston rod 20 passing through a central bore of a disc-shaped block 21 fixedly secured in the housing 14 and having means sealing against the inner wall of the housing and against the piston rod 20. This block 21 thus forms an end wall of a cylinder space 22 enclosed between the block 21 and the piston 19. The block 21 has duct means 23 formed therein which opens into the cylinder space 22 and communicates with a screw nipple 57 screwed in the side wall of the block 21 and housing 14 for connection to a line 24 of a pneumatic control system yet to be described. The outer end portion of the piston rod 20 projecting through the block 21 carries a hinge member 26 pivotally connecting the piston rod to a short cross link (not shown in the drawings) which projects outwardly through a side opening 27 in the housing wall 14 for connection to the free end of the regulating lever 3. The righthand end position, as seen in figure 2, of the piston 1 9 is determined by a discshaped member 25 mounted on the piston rod 20 adjacent the hinge member 26 abutting the abutment screw 1 8. A compression spring 53 is arranged in the hollow screw 18 about the outer end of the piston rod 20 and extends between the bottom of the bore of the screw and the stop member 25. The pressure of the spring 53 thus opposes the resilient return force to which the regulating spindle 2 and lever 3 are normally subjected in conventional fuel-supply pumps.

Adjacent the part of the adjusting device formed by the piston 1 9 with the piston rod 20 and the cylinder space 22 there is provided a retarding device, generally indicated by 28, for the piston movement. This retarding device 28 comprises a cylindrical block 29 fittingly secured in the housing 14 and having two cylindrical chambers 30 and 31 drilled-out therein from opposite ends of the block. The two chambers 30 and 31 are thus separated by a dividing wall portion 32 and are both filled with a suitable liquid, such as oil. A bore 33 extends transversely of the block 29 through this wall portion 32 and communicates with the oil chambers 31 and 30 through channels 34 and 35, respectively. Two regulating valves 36 and 37 are screwed in the cross-bore 33 and are accessible from the outside through suitable openings in the housing wall 14 so as to be adjustable.A removable sleeve 58 covers the outer ends of the valves 36 and 37 which carry O-rings to seal against the wall of the bore 33. Each regulating valve 36 and 37 has an end piece 54 of frusto-conical shape cooperating with a central restricted valve seat portion 55 of the bore 33 so as to form an annular throttling opening which can be adjusted by turning the regulating valve concerned. A check valve 56 is arranged in a recess formed in the end piece 54 of each regulating valve 36 and 37 respectively, which recess opens into the restricted bore portion 55 and, through a port 59 is in direct communication with the passage 34 or 35, respectively, thus forming a bypass for the throttling opening of the regulating valve.In this manner it is obtained that when liquid flows from the chamber 30 to the chamber 31 the flow resistance is determined only by the adjustment of the regulating valve 37 since the check valve 56 in the regulating valve 36 is then open and forms a by-pass for the throttling opening of this latter regulating valve. Similarly, when the liquid flows from the chamber 31 to the chamber 30, the flow resistance is only determined by the adjustment of the regulating valve 36.

A plunger 38 is secured to the front side of the piston 1 9 and extends into the chamber 30, an Oring 39 mounted in a groove in the chamber wall sealing against this plunger. In the position of the piston 19 of fig. 1 the plunger 38 almost completely fills the space of the chamber 30. The block 29 forms at this side an end stop for the left-hand end position of the piston 1 9. At the opposite side of the block 29 the other oil chamber 31 is closed by a resiliently foldable diaphragm 40 which is sealingly secured at its circumferential edge to the block 29. A second plunger member 41 engages the diaphragm 40 and has a smaller outer diameter than the inner diameter of the chamber 31 such that the plunger member 41 together with the diaphragm can move into the chamber 31, as shown in figure 2.

The plunger 41 is guided for axial sliding movement in the cylindrical housing 14 by means of an enlarged hollow base part 42 integral with the plunger 41. A return pressure spring 43 is arranged between the end block 1 5 and this base part 42 of the plunger member 41. When the cylinder space 22 is pressureless this return spring 43, acting through the plunger member 41 and the diaphragm 40 on the oil in the chamber 31, has sufficient force to press the oil through the throttling opening of the regulating valve 36 into the chamber 30 thereby moving the plunger 38 with the piston 19 from the position of fig. 1 to the righthand end position of fig. 2 against the action of the spring 53 until the disc 25 abuts the abutment screw 1 8. In this position the adjustment device 8 together with the rod 7 has its grnatesteffective length between the pump regulating lever 3 and the pivot arm 9. If the accelerator pedal 10 is fully depressed and the arm 9 abuts the end stop 13, the regulating lever 3 occupies an angular position spaced from the upper limit stop 5 of the pump as determined by the adjustment of the abutment screw 1 8. The maximum possible fuel supply for the engine is thus correspondingly restricted so that the maximum engine speed obtainable has a lower limit value of, for example, 2200 r.p.m.

When the cylinder space 22 is pressurized through the line 24 the piston 19 is moved from its position of fig. 2 to its opposite end position of fig. 1 whereby the effective length of the device 8 with the rod 7 decreases and now substantially corresponds to the length of a conventional accelerator pedal rod between the arm 9 and the regulating lever 3. The end stop 13 for the arm 9 is generally so adjusted that this arm abuts the end stop 13 at substantially the same time in which also the regulating arm 3 reaches the upper limit stop 5 of the pump 1. When the pedal 10 is fully depressed, the engine is supplied with the maximum quantity of fuel the pump 1 can deliver whereby when driving in the lower gears the maximum engine power for accelerating the vehicle is available. In this position of fig. 1 the maximum value of the engine speed is, for example, 2500 r.p.m.

The retarding device 28 causes the displacement of the piston between its two end positions through the action of the pressure in the line 24 or of the return spring 43, respectively, to slow down so that also the fuel pump regulating lever 3 is likewise only gradually adjusted on the actuation of the device 8. The regulating valve 36 may be so adjusted that when in the position of fig. 1 the pressure in the cylinder space 22 is relieved, the return spring 43 needs approximately 3 seconds to press the oil from the chamber 31 through the throttling opening of the valve 36 into the chamber 30 until the piston 19 has reached the end position of fig. 2, whereas the other regulating valve 37 may be so adjusted that when the cylinder space 22 is pressurized the piston 19 needs approximately 7 seconds for carrying out its complete stroke in the opposite direction.

The control means of the adjusting device 8 is diagrammatically illustrated in figs. 1 and 2. As shown, the control means comprises a control valve 44 of the slide valve type which in the position of fig. 1 connects the pressure line 24 to a source of compressed air 41 and in the position of fig. 2 connects this line 24 to a vent line 46.

The control valve 44 is of the electro-magnetically operated type and has a field coil 47 having one end connected to earth and its other end connected to the electric power source 60 of the vehicle through a back contact 48 of a control relay 49. Thus, when the contact 48 is closed and the field coil 47 is excited, the control valve 44 is held in the position of fig. 1 in which the cylinder space 22 is connected to the compressed air source 45. The coil of the relay 49 is connected between earth and the power source in series with a normally open contact 50 of a tachograph 51 or other speedometer means of the vehicle and a signal lamp 52. The contact 50 is adjustable in such a manner that this contact is closed by the tachograph at a selected vehicle speed of, for example, 85 km/h.In that case the signal lamp 52 lights up and the relay 49 is excited whereby the relay contact 48 is opened and the field coil 47 is de-excited. Thereby the control valve 44 is moved to the left by a spring (not shown) to the position of fig. 2 in which the cylinder space 22 is no longer connected to the compressed air source 45 but is vented through the line 46. As a consequence, the piston 1 2 is moved by the return spring 43 from the position of fig. 1 to that of fig. 2 in a time interval of approximately 3 seconds whereby the maximum limit value of the engine speed is reduced as above discussed. The spring 53 prevents the possibility of the plunger 38 drawing vacuum in the oil chamber 30 under the action of the resilient return force of the pump regulating lever 3 itself.When the vehicle is accelerated from a low speed with a fully depressed accelerator pedal 10 the control valve 44 will respond when a vehicle speed of 85 km/h is obtained to reset the adjusting device 8 whereupon in the said time inverval of 3 seconds the vehicle speed will gradually increase to 90 km/h corresponding to an engine speed of 2200 r.p.m. When subsequently the vehicle is slowed down to a speed below the selected speed of 85 km/h the cylinder space 22 is again pressurized and, as long as this selected speed is not again passed, the piston 1 9 is returned to the position of fig. 1 in a time period of about 7 seconds, in which position full engine power is again available. In this manner the operation of the control valve 44 by the tachograph contact 50 does not lead to abrupt movements of the pump regulating lever 3. It is particularly avoided that on pressurizing the cylinder space 22 the consequent increase of engine power by the resetting of the regulating lever 3 from the position of fig. 2 to that of fig. 1 could cause an abrupt acceleration of the vehicle.

The assembly of the rod 7 and the adjusting device 8 can be easily mounted on an existing engine in place of the conventional accelerator pedal rod between the pump regulating lever 3 and the pivotal arm 9 in which the fuel-supply pump 1 and the factory adjustment thereof can remain unchanged. This assembly requires only very little extra space allowing it to be used and installed in combination with fuel-supply pumps and vehicle engines of widely varying types.

Claims

1. A speed control governor for regulating the maximum speed of internal-combustion vehicle engines, particularly diesel engines of heavy goods vehicles, said engines being controlled by a fuel-supply pump having a fuel-supply regulating lever, a linkage system connecting said regular lever with a vehicle accelerator pedal, and an end stop for limiting the maximum travel of said regulating lever when the accelerator pedal is fully depressed, said governor comprising adjusting means for resetting said maximum travel of said regulating lever between a higher and a lower end position of said lever and thus between a higher and a lower limit value of the engine speed, respectively, and means for automatically controlling the actuation of said adjusting means in response to a selected travelling speed of the vehicle, said governor further comprising retarding means operatively cooperating with said adjusting means for slowing down said resetting operation of the adjusting means on the actuation thereof.

2. The speed control governor as claimed in claim 1, in which said maximum speed adjusting means includes a cylinder, a piston slidable in said cylinder, return spring means acting on said piston in one direction, said cylinder, piston and spring means being incorporated in said linkage system, a fluid-pressure source, a fluid-control valve operable by said automatic control means to connect said cylinder alternatively to said source and the atmosphere, respectively, to thereby cause said piston to move against said spring means to a first end position in said cylinder corresponding to a minimum effective length of said linkage system or by the action of said spring means to a second end position in said cylinder corresponding to a maximum effective length of said linkage system, respectively, whereby, when the accelerator is fully depressed, in said first piston end position the fuel pump regulating lever occupies said higher lever end position and in said second piston end position said regulating lever occupies said lower lever end position, and in which said retarding means is arranged between said piston and said return spring means, said retarding means comprising a first and a second liquid-filled chamber, a partition member separating said two chambers, a throttling channel formed in said partition member connecting adjacent ends of said two chambers and allowing restricted liquid flow between said chambers, said piston having a part movable in said first chamber and, auxiliary piston means movable in said second chamber in opposition to said piston part in said first chamber, said return spring means acting on said auxiliary piston means.

3. The speed control governor as claimed in claim 2, further comprising a throttle regulating valve in said throttling channel for adjusting the passage of said channel.

4. The speed control governor as claimed in claim 3, comprising two separate independently adjustable regulating valves arranged in series in said throttling channel, each of said two regulating valves having a by-pass and a check valve in said by-pass, the two check valves of said two regulating valves operating in opposite directions of liquid flow.

5. The speed control governor as claimed in claim 2, 3 or 4, further comprising a rod member of said linkage system coupled at one end to said accelerator pedal and connected at its opposite end to said cylinder, said rod member cooperating with said end stop, a piston rod extending from one side of said piston and pivotally secured to said fuel pump regulating lever and a plunger secured to said piston on the opposite side thereof and slidably and sealingly extending into said first chamber of said retarding means.

6. The speed control governor as claimed in any one of the claims 2 to 5, in which said auxiliary piston means of said retarding means comprises a flexible diaphragm sealingly mounted across said second chamber at the end thereof oppositely of said partition mernber, and a second plunger member acting on said diaphragm and axially slidably arranged between the latter and said return spring means.

7. The speed control governor as claimed in any one of the claims 2 to 6, in which said cylinder and piston said retarding means and said return spring means are arranged co-axially in a single elongate cylindrical housing forming part of said linkage system.

8. The speed control governor as claimed in claim 5, 6 or 7, in which said rod member at its end coupled to said accelerator pedal is supported by a pivotally mounted arm, said end stop 'cooperating with said arm.

9. The speed control governor as claimed in any one of-the claims 2 to 8, in which said fuel supply pump includes resilient return means tending to move said regulating lever to its position of lowest fuel supply, said governor further comprising auxiliary spring means acting on said regulating lever in opposition to said resilient return means.

10. A speed control governor substantially as described with reference to, and as illustrated in, the accompanying drawings.