GB2038934A

GB2038934A - Fuel injection Pump for internal Combustion Engines

Info

Publication number: GB2038934A
Application number: GB7941928A
Authority: GB
Original assignee: Robert Bosch GmbH
Current assignee: Robert Bosch GmbH
Priority date: 1978-12-06
Filing date: 1979-12-05
Publication date: 1980-07-30
Also published as: JPS6012933Y2; DE7836111U1; JPS5583252U

Abstract

The regulating rod (10) for angularly displacing the pump pistons (13) of an in-line injection pump, for internal combustion engines for the purpose of varying the fuel delivery quantity, has a first group of sleeve- like shaped regulating members (17) rigidly connected to a carrier rod (19), and a second group of regulating members (18) each displaceable on the carrier rod (19), the regulating members 18 being interconnected by an actuating rod (21), to enable one group (28, 28 ...) of pump pistons to be rendered inoperative. In order to secure the actuating rod (21) against deflection, the entire length of the actuating rod is guided within a longitudinal groove (38) incorporated in the carrier rod (19), the latter passing through all the sleeve-like regulating members (17, 18, 24). Upon longitudinal displacement of the actuating rod (21) during idling and part load operation, only those pump pistons (28, 28...) which are actuated by the second group of regulating members (18) are moved into their stop position, and the other pump pistons (27, 27...) maintain their operating positions, whereby associated engine cylinders are loaded to a greater extent and operate more economically. <IMAGE>

Description

SPECIFICATION Fuel Injection Pump for Internal Combustion Engines The invention relates to fuel injection pumps.

A known fuel injection pump as described in German Utility Model No. 78 14 585, has a composite regulating rod which makes it possible to set one group of pump elements in their stop position during operation of the engine, irrespective of the position of the other pump elements. Favourable exhaust gas emission values are obtained by these measures, particularly during idling or part load operation of the engine, since the engine cylinders still operating are loaded to a greater extent and thus more complete combustion takes place. Thus, fuel consumption is also reduced and less fuel is mixed with the engine lubricating oil, so that undesirable dilution of the lubricating oil is atleast reduced. The shutting-off of cylinders in this manner is also advantageous when one or more cylinders of the engine are operated as an air compressor in, for example, silage vehicles.Only a small amount of space is available for the individual components, since the composite regulating rod is also to be accommodated, as far as possible, in the existing installation space of the in-line injection pump. In the known fuel injection pump, the composite regulating rod induces an actuating rod, which interconnects the parts of the regulating rod acting to move the one group of pump elements to the position, can have only a very small cross section owing to the confined installation conditions, so that there is the risk of buckling or bending of the actuating rod when it is actuated, and the frictional forces, which are thereby increased, increase the actuation force of the actuating rod and also impair regulation of the other parts of the regulating rod which act upon the pump cylinders which are still operating.

Afuel injection pump in accordance with the invention, having pump pistons which are arranged in line and which are axially movable and angularly displaceably guided in pump cylinders and are provided with oblique control edges, and having a composite regulating rod which is mounted in the direction of the longitudinal axis of the pump and which is longitudinally displaceable for angularly displacing the pump pistons for the purpose of varying the fuel delivery quantity, which regulating rod comprising a carrier rod and an actuating rod, which is arranged parallel to the carrier rod and is actuable independently thereof, the regulating rod being provided with two groups of regulating members which respectively engage adjusting members of each pump piston, the first group of which regulating members is rigidly connected to the carrier rod and the second group is displaceable relative to the first group on the carrier rod by means of the actuating rod, the actuating rod being guided, at least substantially over the entire length of the regulating rod provided with the displaceable regulating members, within a longitudinal groove which is incorporated in the carrier rod and whose configuration corresponds to the cross section of the actuating rod.

This has the advantage that, with the retention of the existing installation space for the composite regulating rod, the guidance of the actuating rod is improved to the extent that buckling or bending of the actuating rod by the actuating forces is prevented by virtue of the fact that the actuating rod is continuously guided along its entire length. Moreover, a return spring interposed between the regulating members can have the largest possible external diameter and thus can be of very weak construction.

Advantageously, each of the regulating members of the second group is provided with an opening which pierces its wall and which is engaged by a respective driver member which is secured to the actuating rod and which projects beyond the profile of the carrier rod. The driver members can comprise steel balls which are secured to the actuating rod. Thus, the displaceable regulating member of the second group, are coupled by means which are simple to manufacture and which have proved to be satisfactory and which prevent stressing or sticking of the components and thus permit lowfriction actuation.

Manufacture is further simplified if the wall openings of the regulating members of the second group are in the form of transverse grooves which extend at right angles to the longitudinal axis. Advantageously, all the regulating members of the regulating rod comprise sleeves of equal length. If each of the regulating members of the first group is secured to the carrier rod by means of a fastening pin inserted through a transverse bore in its wall, and all the regulating members are provided with the wall openings for the driver members and also with the transverse wall bores, all the regulating members can be of identical construction, thus reducing the number of parts and facilitating stock-keeping.

It is desirable for all of the regulating members to be sleeve-like and optimum utilisation of the installation space can be achieved if all the sleeve-like members secured to, or guided on, the carrier rod are provided with longitudinal bores through which the carrier rod passes, and if the regulating members are in the form of toothed rack sleeves which mesh with respective pinions.

The invention is further described, by way of example, with reference to the drawings, in which: Figure 1 is a partially sectioned side elevation of a regulating rod of a fuel injection pump, constructed in accordance with the invention, of a fuel injection pump, Figure 2 is a longitudinal section taken on the line Il-Il of Figure 1, additionally showing components of the associated fuel injection pump, some of which are only indicated in outline, and Figures 3, 4 and 5 are cross sections taken on the lines Ill-Ill, lV-lV and V-V of Figure 1 respectively, drawn to a larger scale.

The regulating rod illustrated in Figures 1 and 2 is designated 10 and forms part of a fuel injection pump 11 which is indicated only by dash-dot lines in Figure 2. The injection pump 11 is constructed as an in-line injection pump and has pump pistons 1 3 which are arranged in line and which are guided in pump cylinders 12 so as to be axially movable and rotatable and which are provided with oblique control edges. The pump pistons 1 3 are rotatable, by way of interposed adjusting members 14, by means of the regulating rod 10 which is mounted in the direction of the longitudinal axis of the pump 11 and which is longitudinaliy displaceable for the purpose of varying the delivery quantity.Each adjusting member 14 is in two parts and comprises an adjusting sleeve 1 6 and an adjusting pinion 1 5 clamped to the sleeve 1 6. The sleeve is coupled to the pump piston 1 3 by means (not shown) which permit axial movement of the pump piston 13 but enable the sleeve 1 6 to angularly displace the piston 13.

The regulating rod 10 is composed of a number of components and is therefore designated "composite regulating rod" and has two groups of sleeve-like regulating members 1 7 and 1 8 which cooperate with the adjusting members 14 of the pump pistons 1 3, the regulating members 1 7 of the first group being rigidly connected to a carrier rod 19, and the regulating members 1 8 of the second group being interconnected by means of an actuating rod 21 which is arranged parallel to the carrier rod 1 9 and which is actuable independently of the carrier rod.The regulating members 1 8 are displaceably guided on the carrier rod 1 9 and, by actuating the actuating rod 21 in the axial direction of the regulating rod 10 can be adjusted relative to the regulating members 1 7 rigidly connected to the carrier rod 19, namely in the stop direction designated "-" at the arrow 22. For this purpose, the actuating rod 21 is provided with an actuating member 23 which comprises a sleevelike sliding member 24 which at the same time serves to guide the regulating rod, and an abutment 25 secured to the sliding member 24.

As is indicated by an arrow 26, the actuating rod 21 can be actuated by a solenoid or some other adjusting means by way of the abutment 25 of the actuating member 23 when the corresponding pump elements, actuated by the regulating members 18, are to be adjusted to their "stop" positions. The pump elements cooperating with the regulating member 17 are collectively designated 27, and the pump elements cooperating with the regulating members 1 8 are designated 28.

The regulating members 1 7 and 1 8 of the regulating rod 10 are in the form of toothed racks which are provided with sets of teeth 29 and each of which meshes with a set of external teeth 31, in the form of a toothed segment, provided on each of the adjusting pinions 1 5 of the adjusting members 1 4. Alternatively, however, the regulating members could be provided with grooves for so-called "control arm regulation" without having to depart from the construction, in accordance with the invention, of the regulating rod.

For reasons of standardization, the sleeve-like regulating members 17 and 18 are of equal length and are each provided with a longitudinal bore 32 and 33 respectively for receiving the carrier rod 1 9. As is clearly shown in the sectional illustration of Figure 3, each regulating member 1 7 of the first group is rigidly connected to the carrier rod 19 by means of a fastening pin 35 inserted through a transverse bore 34.

The regulating members 1 8 of the second group are displaceably guided by means of their longitudinal bores 33 on the carrier rod 19, and each of the regulating members 18 is provided with an opening 36 which passes through its wall and which is in the form of a transverse groove extending at right angles to the longitudinal axis of the regulating rod 10.A steel ball 37 acts as a driver member, and secured to the actuating rod 21 by hard soldering, engages the transverse groove and thus drives the regulating member 18 or the interconnected regulating members 1 8 upon displacement of the actuating rod 21 relative to the carrier rod 1 9. If, as is indicated by dash-dot lines in Figure 4, the regulating member 1 8 is also provided with a transverse bore 34', a regulating member of this kind can be interchanged with a regulating member 17, so that stock-keeping is simplified.

As will be seen in Figures 1 to 4, the actuating rod 21 is manufactured from a rectangular profiled bar and is guided within a longitudinal groove 38 which is incorporated in the carrier rod 1 9 and whose cross section corresponds to that of the actuating rod 21. The actuating rod 21 connects all the regulating members 18, displaceable on the carrier rod 19, to the actuating member 23 whose sliding sleeve 24 displaceable on the carrier rod 1 9 is, like the regulating members 18, connected to the actuating rod 21 by means of a steel ball 37' which engages a transverse groove 36'. The entire lengths of three sides of the actuating rod 21 are embraced by the longitudinal groove 38 and the fourth side of the actuating rod 21 is guided by the sleeve-like regulating members 17 and 18, the sliding sleeve 24 of the actuating member 23 and additionally by at least one spacer sleeve 39, thus preventing the actuating rod 21 from being deflected or buckled. Owing to the fact that the actuating rod 21 is guided along its entire length, it can be constructed with a relatively small cross section, since it is only subjected to tensile and compressive stresses.

The cross section of the carrier rod 19, extending over the entire length of the regulating rod, 10 is not weakened to any substantial extent by the longitudinal groove 38, so that the bending strength of the carrier rod 1 9 is virtually unaffected.

The end of the carrier rod 19, which is remote from the actuating member 23, is slidably supported by second sliding sleeve 41 which is secured by means of a fastening pin 35 to the end of the carrier rod 19, as shown in Figure 5. Thus, the sliding sleeve 41 can be made from the same basic material as the regulating members 1 7 and 1 8 and the position of its longitudinal bore 42 corresponds to that of the longitudinal bores 32 and 33 in the members 17 and 18.

Advantageously, the sliding sleeves 24 and 41 directly adjacent to the outermost regulating members 1 7 and 18 result in optimum utilization of the overall length of the regulating rod and thus an optimum length of guidance for support the regulating rod 10 in the housing of the injection pump 11.

The longitudinal bores 32 and 33 in the regulating members 1 7 and 18, the longitudinal bore 42 in the sliding sleeve 41, and a longitudinal bore 43 in the sliding sleeve 24 of the actuating member 23 are disposed eccentrically of the cylindrical outer surfaces of the sleeve-like members, 17, 18, 41 and 24 and, as will be clearly seen in Figures 3, 4 and 5, they are bored through the longitudinal axes of these members so as to be offset towards the wall locations 44 remote from the teeth 29.

As will be seen from the sectional illustration of Figure 5, that side of the cylindrical outer surface 45 of the sliding sleeve 41 which is remote from the wall location 44 incorporates a longitudinal groove 46 which, like a correspondingly acting flat 47 on the sliding sleeve 24, serves to vent the interior space of the pump 11 which accommodates the regulating rod 10, and to lubricate the support points for the sliding sleeve 24 and 41.

That end of the carrier rod 1 9 which is remote from the actuating member 23 is provided with a so-called regulating rod lug 48 and a transverse bore 49 and serves to hinge an adjusting member for the regulating rod 10, and the opposite end of the carrier rod 1 9 is provided with an end member 51 which, after all the movable members of the regulating rod have been assembled, is connected to the carrier rod 1 9 by means of a pin 52, and, in the illustrated embodiment, has a projection 53 which, as is indicated by an arrow 54, can be acted upon by means of, for example, a cut-off solenoid which can displace the entire regulating rod 10 in the stop direction.All the regulating members 1 7 and 1 8 are commonly actuated during this cut-off movement and thus all the pump elements 27 and 28 are also rendered inoperative. However, if, as is indicated by the arrow 26, a switching solenoid acts upon the abutment 25 of the actuating member 23, only the regulating members 18 actuated by the actuating rod 21, and thus only the associated pump elements 28, are displaced into their stop positions by means of the actuating rod 21. This adjusting movement is effected against the force of at least one return spring 55 which abuts at one end against a regulating member 1 7 and at the other end against one of the regulating members 18.As will be seen in Figures 1 and 2, the spacer sleeve 39 acts to determine the illustrated normal positions of the regulating members 18 and at the same time prevents the return spring 55 and/or the forces acting upon a pump piston 13 from displacing the respective regulating member 18 in an uncontrolled manner into a position for delivering the maximum possible quantity of fuel in the event of destruction of the connection between a driver member 37 and the actuating rod 21.

Furthermore, the sleeve 39 also improves guidance of the actuating rod 21 in the region between the adjacent regulating sleeves 1 7 and 18.

The return spring or springs 55 embrace the carrier rod 1 9 accommodating the actuating rod 21, and the external diameters of the spring or springs 55 can be increased up to the diameter of the bearings of the sliding sleeves 24 and 41, so that it is possible to use very weak springs which have virtually no effect on the governor.

Claims

1. A fuel injection pump for an internal combustion engine, having pump pistons which are arranged in line and which are axially movable and angularly displaceably guided in pump cylinders and are provided with oblique control edges, and having a composite regulating rod which is mounted in the direction of the longitudinal axis of the pump and which is longitudinally displaceable for angularly displacing the pump pistons for the purpose of varying the fuel delivery quantity, which regulating rod comprises a carrier rod and an actuating rod, which is arranged parallel to the carrier rod and is actuable independently thereof, the regulating rod being provided with two groups of regulating members which respectively engage adjusting members of each pump piston, the first group of which regulating members is rigidly connected to the carrier rod and the second group is displaceable relative to the first group on the carrier rod by means of the actuating rod, the actuating rod being guided, at least substantially over the entire length of the regulating rod, provided with the displaceable regulating members, within a longitudinal groove which is incorporated in the carrier rod and whose configuration corresponds to the cross section of the actuating rod.

2. A fuel injection pump as claimed in claim 1 in which the regulating members are sleeve-like and are disposed about the carrier rod and the actuating rod.

3. A fuel injection pump as claimed in claim 2, in which each of the regulating members of the second group is provided with an opening which pierces its wall and which is engaged by a respective driver member which is secured to the actuating rod and which projects beyond the profile of the carrier rod.

4. A fuel injection pump as claimed in claim 3, in which the driver members comprise steel balls which are secured to the actuating rod.

5. A fuel injection pump as claimed in claim 3 or 4, in which the wall openings of the regulating members of the second group are in the form of transverse grooves which extend at right angles to the longitudinal axis.

6. A fuel injection pump as claimed in any of the claims 3 to 5, in which all the regulating members of the regulating rod comprise sleeves of equal length.

7. A fuel injection pump as claimed in claim 6 in which each of the regulating members of the first group is secured to the carrier rod by means of a fastening pin inserted through a transverse bore in its wall, and all the regulating members are provided with the wall openings for the driver members and also with the transverse wall bores.

8. A fuel injection pump as claimed in any of claims 2 to 7, in which the regulating rod is provided with at least one respective sliding sleeve adjacent to the first and last regulating member respectively, which sliding sleeves serve to guide the regulating rod.

9. A fuel injection pump as claimed in claim 8, in which one sliding sleeve is secured to the carrier rod, and the other sliding sleeve is displaceably guided on the carrier rod and is connected to the actuating rod.

10. A fuel injection pump as claimed in any preceding claim in which each of the regulating members is provided with toothed rack teeth which mesh with corresponding pinion teeth.

11. A fuel injection pump as claimed in claim 10 when appendant to any of claims 2 to 9, in which all of the sleeve-like members secured to or guided on the carrier rod are provided with longitudinal bores through which the carrier rod passes and in which the longitudinal bores of the sleeve-like members are disposed eccentrically of their cylindrical outer surfaces and are offset towards those wall locations which are remote from the teeth.

12. A fuel injection pump constructed substantially as herein described with reference to and as illustrated in the drawings.