GB2140083A

GB2140083A - Driving I.C. engine fuel pump and distributor

Info

Publication number: GB2140083A
Application number: GB08412636A
Authority: GB
Inventors: Kenji Kumura; Katsuhiko Ubukata
Original assignee: Honda Motor Co Ltd
Current assignee: Honda Motor Co Ltd
Priority date: 1983-05-18
Filing date: 1984-05-17
Publication date: 1984-11-21
Also published as: GB2140083B; JPS59211754A; GB8412636D0; DE3418601A1; JPH0156265B2; DE3418601C2

Abstract

Fuel pump P, Fig. 2, of an internal combustion engine is driven from the valve cam shaft 2 which also drives the distributor D. A cam 11 for driving the pump is separately machined and press fitted onto one end 2a of the cam shaft, and a bracket 3 surrounding that end of the cam shaft supports both the fuel pump and the distributor. <IMAGE>

Description

SPECIFICATION Fuel pump driving means in an internal combusion engine The present invention relates to internal combustion engines and in particular to arrangements for driving a fuel pump thereof.

In one fuel pump driving mechanism of the prior art, an ignition distributor has its rotary shaft formed with a cam by which a drive lever of the fuel pump is actuated. In such a construction, when the fuel pump is driven, its reaction is applied as a bending stress to the rotary shaft of the distributor, to cause deflecting vibrations in such rotary shaft, which vibrations may cause irregular ignition.

One possible solution to that problem is to make the fuel pump driving cam integral with the cam shaft for operating the intake and exhaust valves, so that the driving reaction of the fuel pump will no longer be exerted on the distributor. However, since the driving cam for the fuel pump has an entirely different shape from the intake and exhaust valve cams, it is very difficult to simultaneously machine both types of cam surfaces on the cam shaft, which makes this possible solution inconvenient and expensive from a production point of view.

Certain other prior proposals, such as are disclosed in U.S. Patents 3,338,229 and 3,606,874, have included a separate auxiliary shaft driven by the timing belt or chain for driving the distributor, the fuel pump and other devices, but such arrangements obviously add components to the engine and thereby increase production costs.

According to the present invention there is provided an internal combustion engine having a valve cam shaft drivingly connected at one end to an ignition distributor of the engine, and cam means mounted on the said cam shaft at or adjacent said one end thereof and arranged to drive a fuel pump of the engine.

An embodiment of the invention will now be described by way of example and with reference to the accompanying drawings, in which: Figure 1 is a longitudinal sectional elevation of the cam shaft region of an internal combustion engine according to the invention; and Figure 2 is a sectional end view taken substantially on the line ll-ll of Fig. 1.

As shown in Fig. 1, a valve actuating cam shaft 2 is rotatably supported in a cylinder head 1 forming a part of the body of the engine. The right-hand end portion 2a and the left-hand end portion 2b of the cam shaft 2 protrude from the respective outer sides of the cylinder head 1. A supporting bracket 3 is fixed on one outer side of the cylinder head by means of botls 4 so as to surround the right-hand end portion 2a of the cam shaft.

The housing 5 of an ignition distribution D is fixed to the end face of the supporting bracket 3 by means of bolts 7, while the housing 6 of a fuel pump P shown in Fig. 2 is fixed to the side of the same bracket 3 by means of bolts 8.

The distributor D has a rotary shaft 9 aligned with the cam shaft 2. The rotary shaft 9 is connected to the right-hand end portion 2a of the cam shaft 2 within the supporting bracket 3, by way of a joint such as a conventional Oldham's joint 10 as shown in this embodiment.

Onto the outer circumference of the righthand end portion 2a of the cam shaft 2 there is press-fitted a cylindrical cam 11, formed separately from the cam shaft 2. The drive lever 1 2 of the fuel pump P is positioned to be engaged by the cam 11.

The supporting bracket 3 enclosing the joint 10 and the cam 11 has a lubricant chamber 1 3 formed therein, which communicates through an oil port 1 5 with an oil sump 14 formed in the cylinder head 1 that lubricates the intake and exhaust cams of the cam shaft 2 in the usual manner.

A driven pulley 1 6 is fixed on the left-hand end portion 2b of the cam shaft 2. A timing belt 1 7 runs of the pulley 1 6 and on a drive pulley mounted on a crankshaft (not shown).

In operation, when the engine is running, the cam shaft 2 is driven by the crankshaft through the timing belt 1 7 and the driven pulley 1 6 so that the intake and exhaust valves are opened and ciosed as usual. At the same) time the cam shaft 2 synchronously rotates the rotary shaft 9 of the distributor D through the joint 10, and also rotates the cam 11 to rock the drive lever 1 2 of the fuel pump P. By virtue of this arrangement, the driving reaction of the fuel pump P is taken up by the highly rigid cam shaft 2. Since the cam shaft 2 and the rotary shaft 9 of the distributor D are connected through the joint 10, the rotary shaft 9 can rotate smoothly without being influenced by the aforementioned driving reaction of the fuel pump.

During operation, oil which has lubricated the respective portions of the cam shaft 2 then flows from the oil sump 14 through the oil port 1 5 into the lubricant chamber 1 3 where it lubricates the joint 10 and the cam 11.

It will thus be seen that, at least in the preferred embodiment of the present invention, there is fitted on the outer circumference of one end portion of the valve actuating cam shaft, to which the rotary shaft of the distributor is connected through a joint, a cylindrical cam which is made separately from the cam shaft and by which the drive lever of the fuel pump is actuated. As a result the fuel pump is driven without exerting its driving reaction on the rotary shaft of the distributor, so that such rotary shaft can be synchronuously driven by the cam shaft without being subject to deflecting vibrations, whereby proper ignition can be effected at all times, Moreover, the aforementioned cylindrical cam not only can be machined separately from the valve actuating cam shaft but also can be installed on the cam shaft merely be removing the aforementioned joint, without being interfered with by the distributor. As a result mechanism according to the invention can be so easily produced as to bring about a significant reduction in production costs.

Claims

1. An internal combustion engine having a valve cam shaft drivingly connected at one end to an ignition distributor of the engine, and cam means mounted on the said cam shaft at or adjacent said one end thereof and arranged to drive a fuel pump of the engine.

2. An internal combustion engine as claimed in claim 1, wherein the said cam means comprises a member formed internally to be a press fit on the said one end of the cam shaft.

3. An internal combustion engine as claimed in claim 1 or 2, including a bracket mounted on the engine and supporting the said ignition distributor and fuel pump, which bracket encloses the said one end of the cam shaft, the said cam means, and the said driving connection to the ignition distributor.

4. An internal combustion engine as claimed in claim 3, wherein the said bracket internally defines a lubrication chamber for the said cam means and the said driving connection, connected to receive lubricant from a lubrication chamber of the intake and exhaust valve cams.

5. An interal combustion engine substantially as hereinbefore described with reference to the accompanying drawings.