GB2051407A

GB2051407A - A fuel injection pump governor

Info

Publication number: GB2051407A
Application number: GB8017479A
Authority: GB
Original assignee: Barkas Werke VEB
Current assignee: Barkas Werke VEB
Priority date: 1979-05-31
Filing date: 1980-05-28
Publication date: 1981-01-14
Also published as: DE3013807A1; DD143171A2; DD143171B2; GB2051407B; ATA200880A; SU1067238A1

Abstract

A variable speed governor for diesel engines has provision for full load fuel limitation and is similar to that disclosed in application GB 200 7872A in which flyweights 19 move a fuel pump regulating rod 101 via a lever 16, a drag lever 11 being coupled to the levers 14, 12 and operated by the flyweights to modify the governor effect. This specification describes a modification by which hysteresis due to a biasing spring acting on lever 14 is eliminated the function of the spring being provided for instead by a spring loaded abutment 131. The abutment 131 may also have hydraulically operated adjustment to provide excess fuel for starting. <IMAGE>

Description

SPECIFICATION A control device for injection pumps of diesel engines This invention relates to a control device for an injection pump of a diesel engine, of the kind comprising a casing, a centrifugal governor adapted to be driven by said pump and arranged in said casing, in which governor on an increase of rotational speed an adjusting pin moves in the direction of the injection pump, a regulating rod adapted to be operatively connected to the pump and to be moved non-positively in the direction of increased delivery and positively in the direction of zero delivery by an upper articulation point of a control element which is constructed as a substantially vertical two-armed lever, the regulating rod having an abutment and the control element having a central articulation point which is displaceable by means of an operating lever and a bottom articulation point of the control element being arranged on the adjusting pin of the centrifugal governor, the control device further comprising an arrangement, which is controlled by the centrifugal governor, for limiting full-load delivery in dependence on rotational speed, said arrangement including a substantially vertically arranged drag lever, which is mounted at the top end in the upper zone of the casing and is pivotable in the direction of the adjusting movements of the centrifugal governor, and has an outer slotted guide link embracing a driver member of a substantially vertical pivoting lever which is mounted at its bottom end and is pivotable in the direction of the adjusting movement of the centrifugal governor, on a first arm of which pivoting lever a limiting bell-crank lever is articulated at its apex, an abutment of one arm of the said limiting bellcrank lever extending into the adjustment path of the regulating rod abutment and the other arm of said bell-crank lever being urged pivotally by spring force against an abutment of a second arm of said pivoting lever, in the direction of increased delivery, a reversing abutment being arranged in a stationary position at such a distance from said one arm of the limiting bell-crank lever in the static state that said one arm of the limiting bell-crank lever lies against the reversing abutment only starting from medium engine speeds.

Such control device is disclosed in our copending Application No. 43957/78 (Serial No. 2007872).

In the known control device a spring acts on the pivoting lever against the adjusting movement of the adjusting pin of the centrifugal governor. It has been found in operation of the known control device that it is a disadvantage if the pivoting lever is always acted upon by the force of a spring against the adjusting movement of the centrifugal governor adjusting pin. This condition produces a relatively high friction throughout the control device, the result being relatively high hysteresis. This behaviour of the control device with increased hysteresis prevents optimum adaptation of the injected quantity at the smoke limit and in the throttling-down zone, so that more particularly in these cases the appropriate quantity of injected fuel has not been accurately adjusted.

It is an object of the invention to improve the hysteresis behaviour in the control device of the foregoing kind, i.e. to render frictiongenerating forces operative only to the extent that they are absolutely necessary for operation.

The problem which the invention aims at solving is so to modify a control device of the construction described that the spring force acts on the pivoting lever only in the necessary range of adjustment.

Accordingly, the present invention consists in a control device for an injection pump of a diesel engine, of the kind hereinbefore set forth, wherein an abutment spring is provided which forces the pivoting lever in a direction against the adjusting movement of the adjusting pin, said abutment spring being disposed behind the reversing abutment which is displaceably mounted and so adjusted in the direction of the first arm of said pivoting lever that the arm is in contact in the lower speed range only from a predetermined travel (S2;S3) onwards of the regulating rod, and the reversing abutment firmly abuts the casing positively or non-positively from a higher travel (S4) onwards of the regulating rod.

This basic arrangeinent ensures that hysteresis inside the control device is kept low. Only in the range of the adjusting travels SA1 and SA2 does the force of the spring behind the reversing abutment act for the necessary nonpositive connection of the pivoting lever in relation to the other mechanisms. Advantageously, the excess starting quantity can be adjusted by the optional feature of the invention that the reversing abutment can be shifted out of the range of movement of the pivoting lever. Conveniently to this end, the reversing abutment with the spring is displaceably disposed in an abutment shaft pivctably mounted in the casing. By means Ef a mechanical adjustment, the abutment shaft can be rotated for starting so that the reversing abutment opens up the starting regulating rod path.To enable the starting up operation to be automatically controlled, the reversing abutment with the spring is disposed in an abutment sleeve which is displaceably mounted in the casing and which is preferably retained in the operative position locked in relation to the casing mechanically or hydraulically against a spring force.

It does not form part of the subject matter of this application to describe the hydraulic installation for actuating the abutment sleeve.

In order that the invention may be more readily understood, reference is made to the accompanying drawings which illustrate diagrammatically and by way of example embodiments thereof, and in which: Figure 1 illustrates the kinematic construction of the control device in accordance with the invention in the position of rest, Figure 2 shows a hydraulically adjustable abutment disposed in the casing of the control device, Figure 3 is a cross-section on the line A-A of Fig. 2, Figure 4 shows a mechanically adjustable abutment, Figure 5 is a cross-section on the line B-B of Fig. 4, and Figure 6 is a graph showing the ranges of action of the variable-speed control device.

The entire mechanism of the control device is disposed in a casing (not shown). All bearing points, fastening points, abutments and guides disposed in this casing are given the references G1 to G4. From an injection pump (not shown) a regulating rod 1 extends into the casing of the control device. On the regulating rod 1 an adjusting rod 101 is mounted for pivotal movement. On this adjusting rod 101 is mounted a slide guide 102, which by way of a compression spring 103 is urged in the full load direction against an abutment 1012 fixed on the adjusting rod 101.In the zero delivery direction the slide guide 102 runs against a stop 1011 of the adjusting rod 1 01. This arrangement ensures that the movement of the slide guide 102 is transmitted non-positively to the regulating rod 1 in the direction of increased delivery, whereas in the direction of zero delivery the slide guide 102 acts positively on the stop 1011 and thus on the regulating rod 1. A control element 1 6 is pivotally connected at one -end to the slide guide 102, and at the other end acts on a driver 171 of an adjusting pin.17. On the control element 16 isslidably mounted a slide guide 161 to which is pivotally connected an operating lever 15, which is constructed as a bell-crank lever.The operating lever 1 5 is pivotally mounted at a bearing point G, in the casing for movement between two abutments. When the operating lever 1 5 is moved the slide guide 1 61 pivots about the bearing point G1 in the casing.

A centrifugal governor 1 90 is mounted on a driving shaft 20 of the injection pump. The centrifugal governor 1 90 comprises fly weights 19, which move outwards when the rotational speed is increased and thus transmit regulating movements by way of beli-crank levers 1 8 of the governor 1 90 to the adjusting pin 1 7. The characteristic of the deflection of the fly weights 1 9 is determined by compression springs 4 and 5 which act against the centrifugal force of the fly weights. These compression springs 4 and 5 of the centrifugal governor 1 90 are practically not prestressed at zero rotational speed.The adjusting pin 1 7 is mounted in known manner for sliding in a guide G4 of the governor.

A drag lever 11, which is mounted at its top end in a bearing G2 in the upper zone of the casing and is pivotable in the direction of the adjusting movement of the centrifugal governor 190, embraces by its guide link 11 2 the driver 171 of the adjusting pin 17.

By means of a central slotted guide link 111 the drag lever 11 is positively connected to a pivotal lever 14. A driver 141 of the lever 14 projects into the link 111. The lever 14 is pivotably mounted at the bearing point G3 in the lower part of the casing and is pivotable in the direction of the regulating movement of the centrifugal governor 1 90.

Furthermore, the lever 1 4 has an arm 1 43 at whose end a limiting bell-crank lever 1 2 is pivotally connected at its apex. The arm 121 of the lever 1 2 is contrinuously urged by a tension spring 7 against an abutment screw 1420 on the arm 142. The other arm 122 of the lever 12 carries an abutment 1 23 against which bears an abutment 104 of the rod 1 at maximum injection delivery. At a predetermined distance from the arm 1 22 is displaceably disposed a reversing abutment 131 which is more particularly referred to hereinbelow in connection with the operation of the control device.

The whole mechanism of the control device described corresponds to our co-pending Application No. 43957/78, (Serial No 2007872) although the abutment 131 shown in Fig. 1 is differently constructed, and a tension spring engaging via abutment arm 142"with the pivoting lever 14 and constantly acting against the adjusting direction of the adjusting pin 1 7 is dispensed with. According to the invention the basic function of the afore-mentioned spring has been transferred to the abutment 131, for which purpose the latter is constructed with provision for displacement against the force of a spring 1 33.

This ensures the action of a spring force against the adjusting direction of the pivoting lever 14 and of the lever arm 1 22 articulated thereto exclusively in the zone of negative adjustment SA1 (Fig. 6). Figs. 2 and 3 show in detail a construction of a hydraulically controlled abutment 131, disposed in the casing, when the operating lever 1 5 is in its position of rest (Fig. 1).

The hydraulically operated abutment 131 is connected via a connection 206 and a separate control system, connected upstream thereof, to the engine oil circuit. Direct connection to the engine oil circuit does not ensure an extra starting quantity.for all operational conditions occurring during the starting phase. At starting, there is no pressure in a pressure chamber 205, and an abutment sleeve 200 is urged by a pre-stressed spring 201 disposed between a support ring 203 and a thrust ring 2002 until the right-hand end face (as viewed in Fig. 3) of an abutment groove 2001 contacts a casing abutment 204.This ensures that in the starting position of the operating lever 1 5 (pivoting arm 1 22 abuts reversing abutment 1 31) the extra starting quantity is obtained which corresponds to the regulating rod travel SStS4 As engine speed increases up to speed n2 (Fig. 6) the oil pressure rises, and after its connection at speed n1 to the chamber 205 causes a movement to the right of the abutment sleeve 200 until the left-hand end face of the groove 2001 contacts the casing abutment 204; at the same time, interaction between abutment 1 23 and regulating rod abutment 104 pushes the regulating rod 1 back, with further pre-stressing of the compression spring 103 (Fig. 1), and the abutment spring 1 33 does not yield, due to the rigidity of its construction. Only with further speed increase does there take place in the speed range n3 to n4 (Fig. 6) a relative movement between the reversing abutment 131 and the abutment sleeve 200, due to the yielding of the abutment spring 1 33. The tension spring 7 must be adjusted to the entire system. Above a speed n4, positive adjustment takes place as disclosed in the co-pending application.

Any leakage oil collecting, passes via the joint system of the control device and pump oil back to the engine.

A mechanical arrangement is also conceivable for displacing the abutment sleeve 200.

Figs. 4 and 5 illustrate an- arrangement in which the reversing abutment 1 31 is mounted in an abutment shaft 301 and during the starting operation is pivotable anti-clockwise (as viewed in Fig. 4) so that the regulating rod path Sst-S4 is opened up. In this case pivoting against the force of a return spring 302 is effected mechanically via a lever 300 by selectable adjusting motors. In the speed range n3 . . . n4 (Fig. 6) negative adjustment is effected by the lever arm 1 22 abutting the reversing abutment 131 when speed rises and compressing the abutment spring 133, overcoming the adjusting travel SAA At a speed n4 the left-hand end face of the abutment 131 contacts abutment member 135, which bears axially with shaft 301 against end abutment 305. In the initial position and also during the starting operation, the end positions are fixed by co-operation between pivoting abutment 306, rigidly attached to shaft 301, and a pin G5 rigidly attached to the casing.

Claims

1. A control device for an injection pump of a diesel engine, of the kind hereinbefore set forth, wherein an abutment spring is provided which forces the pivoting lever in a direction against the adjusting movement of the adjusting pin, said abutment spring being disposed behind the reversing abutment which is displaceably mounted and so adjusted in the direction of the first arm of said pivoting lever that the arm is in contact in the lower speed range only from a predetermined travel (S2;S3) onwards of the regulating rod, and the reversing abutment firmly abuts the casing positively or non-positively from a higher travel (S4) onwards of the regulating rod.

2. A control device according to claim 1, wherein the reversing abutment is displaceable out of the range of movement of said first arm of the pivoting lever.

3. A control device according to claim 2, wherein the reversing abutment with the abutment spring is displaceably disposed in an abutment shaft pivotably mounted in the casing.

4. A control device according to claim 2, wherein the reversing abutment with the abutment spring is disposed in an abutment sleeve which is displaceably mounted in the casing and which is retained in the operative position locked in relation to the casing mechanically or hydraulically against a spring force.

5. A control device for an injection pump of a diesel engine, substantially as herein described with reference to and as shown in the accompanying drawings.