GB2128267A - Fuel injection pumping apparatus - Google Patents

Abstract

A fuel injection pumping apparatus for supplying fuel to a multi-cylinder internal combustion engine includes a housing 10 formed from steel and accommodating a reciprocable pump plunger 14 and a rotary distributor member 22 both of which are actuated from a rotary drive shaft 31 in the one case by a cam 19 and in the other case by gearing 29, 30. A lightweight casing 35 is secured to a flange 11 on the housing and encloses the drive shaft and associated parts but has an aperture through which one end portion of the shaft extends. The shaft is carried by bearing housings parts 32, 33 which are secured to the housing 10. <IMAGE>

Description

SPECIFICATION Fuel injection pumping apparatus This invention relates to fuel injection pumping apparatus for supplying fuel to a multi-cylinder internal combustion engine.

Various forms of such apparatus are known in the art. The so-called "in-line" form of apparatus has a plurality of pump plungers which are located in respective bores with the axes of the bores generally arranged in a common plane. The bores may be formed in pump barrels respectively and are carried in a steel housing. The apparatus also includes a cam shaft the axis of which is disposed in the aforesaid plane and the cam shaft defines cams for operating the plungers respectively. The cam shaft is supported in bearings located in a casing to which the aforesaid housing is secured.

In order to reduce the weight of the apparatus and in order to facilitate manufacture of the casing, the latter is usually formed from an aluminium or other light alloy casting. It does however have to afford sufficient support to the cam shaft to ensure that there is substantially no flexure during operation of the apparatus, such as might cause the pumps to deliver differing amounts of fuel. As a result the casing, in practice, is of considerable thickness. Another form of apparatus is of the rotary distributor type in which a rotary distributor member is mounted in a steel sleeve. The cam means for actuating the pumping plungers is mounted in a separate part of the apparatus and again in order to reduce the weight and facilitate manufacture, this part is usually formed from an aluminium or other light alloy casting.

A further form of apparatus is known in which a single plunger is reciprocated within a bore and a distributor member is provided to distribute the fuel delivered by the plunger to a number of outlets in turn. It is convenient to locate the plunger and the distributor member in a steel housing with the high pressure fuel passages and outlets being formed in the same housing. The established practice would be to locate the cam shaft for the pump in a separate casing secured to the housing, with the casing being formed from an alloy for the sake of lightness. The casing would have to be rigid to withstand the loads imposed upon it and also provide the necessary support for the apparatus when mounted on the associated engine. Whilst it is not impossible to design a suitable casing for this form of apparatus it is felt that the design would result in a complex and bulky component.

The object of the present invention is to provide a fuel injection pumping apparatus in a simple and convenient form.

According to the invention a fuel injection pumping apparatus for supplying fuel to a multicylinder internal combustion engine comprises a housing formed from steel or like high strength material, a reciprocable pumping plunger accommodated within said housing, a distributor member accommodated within the housing for distributing fuel delivered by said plunger to outlet ports in turn, said outlet ports also being located in said housing, a rotary drive shaft, means carried by the drive shaft for actuating the plunger and distributor member, a bearing housing for the shaft, said bearing housing being defined in part by said housing and in part by a further detachable member, and means for securing said detachable member to the housing.

An example of a fuel injection pumping apparatus in accordance with the invention will now be described with reference to the accompanying drawings, in which: Figure 1 shows in side elevation, part of the apparatus; and Figure 2 is a view in the direction of the arrow A of Figure 1.

Referring to the drawings the apparatus comprises a housing 10 which conveniently is formed from a suitable steel, the housing also defining an outwardly extending peripheral flange 11. Located within the housing is a first bore 12 in which is retained a pump barrel 13. The barrel is formed from hardened steel and defines a bore accommodating a pumping plunger 14. At its lower end, the plunger has a head 1 5 which engages a tappet assembly 16 including a roller 1 7.

Conveniently the barrel is retained within the bore by means of a threaded ring 1 8.

The plunger is movable upwardly to effect delivery of fuel from a pumping chamber in part defined by the bore in the barrel, by means of a rotary cam 1 9 and a coiled compression spring may be provided to effect movement of the plunger in the opposite direction. It is preferred however that the plunger is positively returned and for this purpose a plunger return mechanism (not shown) may be provided, the return mechanism being actuated by the cam 1 9.

Also formed in the housing 10 is a further bore 20 in which is located a sleeve 21 defining a bore for a rotary distributor member 22. The sleeve 21 is formed from hardened material and is retained within the bore in any convenient manner. The distributor member 22 is driven from a subsidiary drive shaft 23 which is carried in a bearing sleeve 24 secured by means of a retaining ring 25 in an enlarged portion 26 of the bore 20. Located between the ring 25 and the step defined in the bore 20 is a low pressure fuel supply pump generally indicated at 27 and having a rotary part 28 which is keyed to the shaft 23. The axis of rotation of the distributor member is parallel to but spaced from the axis of the plunger.

The shaft 23 extends from the bearing sleeve 24 and mounts a pinion 29 the teeth of which mesh with a further pinion 30 carried on a drive shaft 31, the shaft 31 also mounting the cam 19.

The axis of rotation of the drive shaft is at right angles to the axes of movement of the distributor member and plunger but is contained in the same plane.

The operation of the apparatus will be appreciated by those skilled in the art. The distributor member delivers fuel in turn to a plurality of outlets 22A formed in the housing and connected in use to the injection nozzles of the associated engine, during successive inward movements of the pumping plunger. The iow pressure pump 27 delivers fuel to the aforesaid pumping chamber and its pressure will be controlled by suitable valve means not shown.

Moreover, since the plunger is of a constant displacement type, means (not shown) is provided to determine the amount of fuel which is supplied to each outlet.

The drive shaft 31 is provided with a tapered portion for the reception in use, of a drive gear or a toothed member whereby the shaft can be driven in timed relationship with the associated engine.

In order to support the drive shaft, a pair of bearing housings are provided on opposite sides of the cam 19. One half of each bearing housing is defined by extended portions of the housing 10 and the other parts of the bearing housings are defined by detachable members 32, 33. As shown in Figure 2, the housing and the detachable members 32, 33 define flanges respectively which can be secured together by means of bolts 34.

This form of construction provides proper support for the drive shaft and transmits the thrust applied to the drive shaft by the tappet assembly, direct to the housing 10. The drive shaft since it is supported on both sides of the cam, is provided with adequate bearing area for it to withstand any loads which may be imposed upon it by the driving gear or pulley by which it is connected to the rotary parts of the engine.

In the example illustrated in the drawings, the apparatus is provided with a casing generally indicated at 35. The casing is provided with a peripheral flange whereby it can be secured in sealing relationship to the flange 11 on the housing 10 and it is also provided with an aperture through which extends the end portion of the drive shaft 31. The casing may be formed from thin sheet material which may be of a metallic or a non-metallic nature. Also in the example illustrated, a mounting bracket 36 is provided which extends about the drive shaft and is conveniently connected by means of screws, to the member 33. The mounting bracket is also provided with an extension 37 which is secured again by screws, to the flange 11. Conveniently a spacer member 38 is provided between the flange and the extension 37. Moreover, the mounting carries a seal 40 to prevent escape of lubricant from the casing.

It is envisaged that there may be no need to provide the casing 35 or for that matter, the mounting 36 with its extension 37 and the distance piece 38. It may be possible to mount the apparatus by means of the flange 11 in a suitable recess defined in the structure of the associated engine.

By the arrangement described a pumping apparatus is provided which has a very rigid mounting for its drive shaft. It is possible with the arrangement to mount the apparatus so that it is partly accommodated within the structure of the associated engine or if this is not required, to provide a simple casing to form an enclosure for exposed rotary parts of the apparatus. Various forms of mounting can be designed for attachment to the housing of the apparatus to suit particular engine applications.

Claims (8)

1. A fuel injection pumping apparatus for supplying fuel to a multi-cylinder internal combustion engine comprising a housing formed from steel or like high strength material, a reciprocable pumping plunger accommodated within said housing, a distributor member accommodated within the housing for distributing fuel delivered by said plunger to outlet ports in turn, said outlet ports also being located in said housing, a rotary drive shaft means carried by the drive shaft for actuating the plunger and distributor member, a bearing housing for the shaft, said bearing housing being defined in part by said housing and in part by a further detachable member, and means for securing said detachable member to the housing.

2. An apparatus according to Claim 1 in which said distributor member is a rotary distributor member the axis of rotation of which is at right angles to the axis of rotation of the drive shaft, the distributor member being driven through gearing from the drive shafts.

3. An apparatus according to Claim 2 in which the means for actuating the plunger comprises a cam, said bearing housing being located on one side of said cam, the apparatus including a further bearing housing located on the other side of the cam the further bearing housing being defined in part by said housing and in part by a further detachable member.

4. An apparatus according to Claim 3 in which said detachable members and said housing define respective flanges, the flanges of said detachable members being secured to the respective flanges of the housing by bolts.

5. An apparatus according to any one of the preceding claims in which said housing is provided with a peripheral flange.

6. An apparatus according to Claim 5 including a casing adapted to be secured to said peripheral flange. said casing enclosing the actuating means for the distributor member and plunger and the drive shaft, the casing being provided with an aperture through which extends the end portion of the drive shaft, said casing being formed from thin sheet material.

7. An apparatus according to Claim 6 including a mounting bracket secured to said detachable member, said mounting bracket surrounding said shaft and defining an extension which is secured to said peripheral flange.

8. A fuel injection pumping apparatus for supplying fuel to a multi-cylinder internal combustion engine comprising the combination and arrangement of parts substantially as hereinbefore described with reference to the accompanying drawings.