GB2282673A

GB2282673A - Centrifugal governor for a fuel injection pump of an internal combustion engine

Info

Publication number: GB2282673A
Application number: GB9419870A
Authority: GB
Inventors: Manfred Schwarz; Carlos Alvarez-Avila
Original assignee: Robert Bosch GmbH
Current assignee: Robert Bosch GmbH
Priority date: 1993-10-04
Filing date: 1994-10-03
Publication date: 1995-04-12
Anticipated expiration: 2014-10-03
Also published as: GB2282673A8; FR2710950A1; KR950011821A; KR100307482B1; GB2282673B; DE4333778A1; FR2710950B1; JPH07158470A; GB9419870D0

Description

2282673

DESCRIPTION CENTRIFUGAL GOVERNOR FOR A- -FUEL INJECTION PUMP OF AN INTERNAL COMBUSTION ENGINE

The present invention relates to a centrifugal governor for a fuel injection pump of an internal combustion engine.

In a known centrifugal governor (EP 0 168 613 B1) a spring end of an idle spring remote from a start lever is fixed in the housing of a fuelinjection pump. As the so-called 'hoUSing-fixed idle spring' (LPG) loads the start lever in the same pivot direction as a control spring coupled to a rotational speed adjusting lever loads the tensioning lever, any adjustment to the rotational speed adjusting lever to higher rotational speeds by virtue of an accelerating process causes the idle spring to be detensioned. As a result of this, when starting carefully, such as in particular when manoeuvring or on inclines, the load exerted causes an interruption in the rotational speed, which can only be recaptured by heavily depressing the accelerator pedal, which in turn is associated with an undesired acceleration of the motor vehicle. Therefore, starting during a manoeuvre operation or on inclines involves considerable problems for the driver.

In accordance with the present invention, there -2is provided a centrifugal governor for a fuel injection pump of an internal combustion engine, comprising a tensioning lever pivotable about an axis and actuated by a control spring of a rotational speed adjusting lever which is movable by way of an accelerator pedal, a start lever pivotable about the same axis and which adjusts a fuel-injection quantity control member of a fuel-injection pump, the start lever being actuated by a rotational speed signalling device in a pivot direction opposite to the pivot direction of the tensioning lever and which after a rotational speed necessary for overcoming the pretensioning force of a start spring supported between the start lever and the tensioning lever is achieved lies against the tensioning lever, and an idle spring comprising a tension spring which engages the start lever and loads the start lever in a pivot direction corresponding to the pivot direction of the tensioning lever, wherein the spring end of the idle spring remote from the start lever engages a compensating lever which is pivotable about an axis, the compensating lever being supported by a bracket against a connecting member path of a connecting member rigidly connected to the tensioning lever and the connecting member path is formed in such a manner that when the tensioning lever is pivoted causing the connecting member to pivot, -3the connecting member part pivots the compensating lever by way of its bracket in such a manner that the pretensioning of the idle spring remains at least partially maintained.

The centrifugal governor in accordance with the present invention has the advantage that, by fixing the idle spring to a pivotable compensating lever remote from the start lever and by supporting the compensating lever at a connecting member pivoting with the tensioning lever, when pivoting the start lever coupled to the rotational speed adjusting lever, the engagement point of the idle spring remote from the start lever moves as one with this said lever, resulting in the resilient pretensioning of the idle spring being substantially maintained. The detensioning of the idle spring, which is the cause of the problems when starting up, is reliably prevented and it is possible to manoeuvre the motor vehicle comfortably.

In a preferred embodiment of the invention the pivot axis of the compensating lever is disposed on an adjusting lever which pivots about a fixed axis and the lever position of the adjusting lever can be adjusted by means of an adjustment means. This adjustment lever renders it possible to adjust the idle spring and to set the desired idle speed rotational.

To this end, as proposed by a further embodiment of the invention, the adjustment lever is of a twoarm design, wherein one lever arm accommodates the pivot axis of the compensating lever and the other lever arm lies in a non-positive manner against an adjustable stop. This non- positive arrangement of the adjusting lever at the stop is produced by means of a stop spring which loads the adjusting lever in the pivot direction to the stop:

The adjusting lever also provides the possibility of setting a higher idling speed for certain operating conditions. To this end, the adjustment means as proposed by an advantageous embodiment of the invention comprise a second adjustable stop, which is disposed in the pivot path of the adjusting lever in such a manner that the adjusting lever comes to lie against the second stop after a pivot movement about a predetermined angle of rotation against the restoring force of the stop spring. In order to set the increased idle rotational speed, the adjusting lever is switched over by virtue of the means known per se for the purpose of increasing the idle rotation speed. which means are pneumatic or operate in dependence upon the temperature.

By way of example only, a specific embodiment of A -5the present invention will now be described with reference to the accompanying drawing which shows a schematic illustration of the lateral view of an embodiment centrifugal governor for a fuel-injection pump of an internal combustion engine in accordance with the present invention.

In the case of the centrifugal governor, illustrated in a simplified form in the drawing, for a fuel-injection pump, a pump piston 10 of a fuelinjection pump is moved by Virtue of known means (not illustrated) in a reciprocating and simultaneously rotating manner. A T-shaped relief duct 11 extending in the pump piston 10 leads from a (likewise not illustrated) pump working chamber which is defined by the pump piston 10, to the surface of the pump piston 10 and is controlled there by an injected fuel quantity control member which is designed as a slide valve 12. During the reciprocating movement of the pump piston 10 and after a certain travel has been completed, the relief duct 11 is opened earlier or later depending upon the position of the slide valve 12, causing the fuel-injection process to be interrupted. The axial position of the slide valve 12 determines in this way the quantity of fuel injected.

The slide valve 12 is displaceable by a start lever 13, which is pivotably mounted about a housing- -6fixed axis 14 on the pump housing (not illustrated here) of the fuel- injection pump and which start lever in order to actuate the slide valve 12 engages in said slide valve by means of a spigot 15 in a blind bore 16 of the slide valve 12. A tensioning lever 17 is rotatably mounted about the same axis 14, the free end of the tensioning lever 17 being engaged by a control spring 18 in the form of a tension spring and the other end thereof being connected to a rotational speed adjusting lever 19. The rotational speed adjusting lever 19 can pivot about a housing-fixed axis 20 between two adjustable end stops 21, 22, wherein the said lever is pivoted by way of the accelerator pedal being operated by the driver. A rotational speed signalling device, which is formed here as a flyweight governor 23 and is driven synchronously with the rotational speed of the internal combustion engine engages the start lever 13. In the case of this flyweight governor 23 flyweights displace in dependence upon the rotational speed an adjusting sleeve 24, which for its part abuts the start lever 13 and displaces the said start lever against a start spring 25 which is supported between the tensioning lever 17 and the start lever 13 progressively in the direction towards a stop 26 on the tensioning lever 17. When the start lever 13 t 1 -7moves into position against the stop 26, the tensioning lever 17 and the start lever 13 are coupled together and a pivot movement of the tensioning lever 17 in an anti-clockwise direction causes the start lever 13 to displace the slide valve 12 towards the right in the drawing in a direction which increases the fuel quantity.

Prior to starting the internal combustion engine, the start lever 13 under the influence of the start spring 25 lies against the adjusting sleeve 24 which is located in its inoperative position. The slide valve 12 is displaced into a position in which a greater quantity of fuel is injected for the start. As soon as the internal combustion engine is started, the flyweights are displaced away from each other and displace the adjusting sleeve 24 towards the right in the drawing. Consequently, the start lever 13 is pivoted about the axis 14, until after completing a pivot path it comes to lie against the stop 26 at the tensioning lever 17, wherein the higher quantity of fuel injected for the start is controlled by the slide valve 12 displaced in this way. This position of the centrifugal governor 23 and the slide valve 12 is illustrated in the drawing.

The start lever 13 is engaged by an idle spring 27 in the form of a tension spring and the other end -8of the said spring is hooked onto a compensating lever 28. The compensating lever 28 is pivoted about an axis 29, which is received in one lever arm 301 of a two-arm adjusting lever 30. The adjusting lever 30 is pivotably mounted on a housing-fixed axis 31 and lies with its other lever arm 302 under the influence of a stop spring 32 against an adjustable stop 33. The compensating lever 28, which can pivot about the axis 29 on the adjusting lever 30, is supported by a bracket 34 at a curved conn6cting member path 35, which is formed on a connecting member 36 which is rigidly connected to the tensioning lever 17. The connecting member path 35 is formed in such a way that, when the tensioning lever 17 is pivoted in the drawing in anti-clockwise direction, the compensating lever 28 is pivoted by virtue of the bracket 34 sliding along the connecting member path 35, and likewise in the drawing in the anti- clockwise direction, in such a manner that the pretensioning of the idle spring 27 remains substantially unchanged.

When for example the rotational speed adjusting lever 19 assumes the position illustrated in the drawing and the internal combustion engine drives the flyweight governor 23 at rotational speeds above the idle rotational speed in such a manner that the start spring 25 is compressed and the idle spring 27 is 1 -9correspondingly pretensioned, then this produces a constant fuel- injection quantity, in that it holds the slide valve 12 in the required position. As soon as the driver accelerates, i.e. pivots the rotational speed adjusting lever 19 out of the illustrated position, the slide valve 12 is displaced into a position for a higher fuel-injection quantity, thus increasing the rotational speed of the internal combustion engine. In the case of a higher rotational speed, the tensioning lever 17 is displaced against the force of the control spring 18 by way of the flyweight governor 23 and the start lever 17 and the fuel-injection quantity is controlled in such a manner that no further increase occurs in the rotational speed.

When the tensioning lever 17 pivots in an anticlockwise direction, the start lever 13 lying against the stop 26 on the tensioning lever 17 also pivots in an anti-clockwise direction. The compensating lever 28 is likewise pivoted in an anti-clockwise direction by way of the connecting member 36, the connecting member path 35 and the bracket 34, so that the idle spring 27 is not detensioned. This so called inner coupling of the idle spring 27, which prevents the detensioning thereof, renders it possible to prevent the known start-up problems of the motor vehicle, -10above all on inclines or when manoeuvring the motor vehicle.

The adjustment of the pretensioning of the idle spring 27 is carried out by way of the adjusting lever 30. The stop 33 of the said adjusting lever is formed by an adjustment screw 37. which is axially displaceable by being rotated and changes the adjusting lever 30 into its pivot position fixed by the stop 33.

In order to achieve an-increased idle rotational speed during a cold start of the internal combustion engine, adjusting means engage the lever arm 302 of the adjusting lever 30, which adjusting means are known for example under the term temperature-dependent or pneumatic idle running increase (PLA, TLA) and are symbolized in the drawing by an arrow 38. During a cold start of the internal combustion engine, the adjusting means 38, which are effective in dependence upon the temperature, pivot the adjusting lever 30 against the force of the stop spring 32 until it is in position against a second stop 39 disposed on the opposite side of the lever arm 302. The stop position of the adjusting lever 30 can be adjusted with a high degree of precision by virtue of the second stop 39 which is likewise provided with an adjustment screw 40. When the adjusting lever 30 comes to lie against -lithe second stop 39, the pretensioning of the idle spring 27 increasesr causing the start lever 13 to move into position against the stop 26 at the tensioning lever 17 only in the case of an increased idle rotational speed. After the end of the warm running phase, the TLA becomes ineffective and the adjusting means 38 releases the adjusting lever 30, which is pivoted back under the influence of the stop spring 32 against the first stop 33. Consequently, the pretensioning of the idle spring 27 is reduced and the idle rotational speed desired for the warm internal combustion engine is again established automatically.

Claims

-12CLAIMS

1. A centrifugal governor for a fuel injection pump of an internal combustion engine, comprising a tensioning lever pivotable about an axis and actuated by a control spring of a rotational speed adjusting lever which is movable by way of an accelerator pedal, a start lever pivotable about the same axis and which adjusts a fuel-injection quantity control member of a fuel-injection pump, the start lever being actuated by a rotational speed signalling device in a pivot direction opposite to the pivot direction of the tensioning lever and which after a rotational speed necessary for overcoming the pretensioning force of a start spring supported between the start lever and the tensioning lever is achieved lies against the tensioning lever, and an idle spring comprising a tension spring which engages the start lever and loads the start lever in a pivot direction corresponding to the pivot direction of the tensioning lever, wherein the spring end of the idle spring remote from the start lever engages a compensating lever which is pivotable about an axis, the compensating lever being supported by a bracket against a connecting member path of a connecting member rigidly connected to the tensioning lever and the connecting member path is formed in such a manner that when the tensioning lever -13is pivoted causing the connecting member to pivot, the connecting member part pivots the compensating lever by way of its bracket in such a manner that the pretensioning of the idle spring remains at least partially maintained.

2. A centrifugal governor as claimed in claim 1, wherein the pivot axis of the compensating lever is disposed on an adjusting lever which can pivot about a fixed axis and the lever position of the adjusting lever can be adjusted by medns of an adjustment means.

3. A centrifugal governor as claimed in claim 2, wherein the adjusting lever has two arms and one lever arm accommodates the pivot axis of the compensating lever and the other lever arm lies in a non-positive manner against an adjustable stop.

4. A centrifugal governor as claimed in claim 3, wherein the non-positive arrangement is produced by virtue of a stop spring loading the adjusting lever in a pivot direction towards the stop.

5. A centrifugal governor as claimed in claim 4, wherein the adjusting means comprise a second adjustable stop, which is disposed in the pivot path of the adjusting lever in such a manner that the said adjusting lever lies against the second stop after pivoting about a predetermined angle against the restoring force of the stop spring.

6. A centrifugal governor as claimed in claim 5, wherein in order to pivot the adjusting lever against the restoring force of the stop spring means engage the adjusting lever to increase the temperaturedependent or pneumatic idle running.

7. A centrifugal governor as claimed in any of the preceding claims, wherein the rotational speed signalling device comprises a flyweight governor.

8. A centrifugal governor substantially as herein described, with refefence tot and as illustrated in. the accompanying drawing.

9. A fuel injection pump comprising a centrifugal governor as claimed in any of the preceding claims.

10. An internal combustion engine comprising a fuel pump as claimed in claim 9.