JPH0472065B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a fuel system for a compression ignition engine that includes a reciprocating plunger fuel injection pump having an outlet and a fuel injection nozzle having an inlet connected to the outlet.

Conventionally, an injection pump connected to an injection nozzle by a pipe is installed within a pump body attached to an engine structure at a position where the injection pump can be driven by the engine. In an attempt to reduce the injection time, that is, the period during which fuel is supplied to the engine's fuel chamber in consideration of the rotation angle of the engine's crankshaft, it has been proposed to integrate the injection nozzle into the pump. In this case, the pump is driven by a cam mounted on the camshaft of the engine via a suitable rocking lever. In the known device, the axis of the injection nozzle is aligned with the axis of the plunger of the pump. The nozzle body extends into the combustion chamber of the engine and typically has a shoulder that is clamped to a shoulder in a bore formed to receive the injection nozzle.

In the cylinder head of an engine, in particular in the part forming the combustion chamber, passages are formed, such as, for example, air inlet passages, exhaust passages, coolant passages and holes in valve stems. If the engine is large, it is possible to ensure that the step is provided with a suitable support so as to be able to absorb the clamping loads and the mechanical loads placed on the pump by the cam during fueling.
In the case of high-speed small engines, the dimensions of the injection nozzle cannot be reduced, so the problem of providing suitable support becomes extremely important.

SUMMARY OF THE INVENTION An object of the present invention is to provide a simple and convenient fuel system for a compression ignition engine that overcomes the above-mentioned problems.

A compression ignition type engine fuel system according to the present invention includes a body installed on a cylinder head of an engine, a mounting part integrally formed with this body, and a fuel system carried by the mounting part that passes through a hole in the cylinder head to the engine. an injection pump having a fuel injection nozzle extending into the combustion space of the fuel injection nozzle; a reciprocatable plunger disposed within the body such that the line of action is offset from the axis of the fuel injection nozzle; a surface on the body that engages and has a complementary shape to the surface of the cylinder head for transmitting at least a portion of the force acting on the body to the cylinder head.

In FIG. 1, reference numeral 10 denotes an engine (compression ignition type engine), which has a cylinder head 11 bolted to an engine block 12. As shown in FIG. Engine block 12
The cylinder 13 into which the piston 14 is inserted
is provided. Especially in this case, the piston 14
A recess is formed in the combustion chamber 15, and this becomes a combustion chamber 15. A pair of passages (one of which is indicated at 16) are formed within the cylinder head 11, each of which directs combustion air into the combustion space (combustion chamber).
The exhaust gas is supplied to the combustion chamber, and the exhaust gas is exhausted from the combustion space (combustion chamber). The opening of the port is in the wall of the cylinder constituting the upper wall of the combustion chamber 15. Poppet valves (one of which is indicated at 17) are operated by cams 18A formed on a camshaft 18 supported by the cylinder head 11 to direct the flow of gas through said passage 16. Control.

The fuel system is a combination of a fuel injection pump 19 and a fuel injection nozzle 20. The fuel injection nozzle 20 has a tip extending through the wall of the cylinder head 11 into which fuel is injected into the combustion chamber 1.
An exit orifice is formed that points towards 5.

The fuel injection pump 19 has a body 19A to which a fuel injection nozzle 20 is fixed, and a plunger 20A that partially projects from the body 19A. A cam 18A on the camshaft 18 is attached to the plunger 20A.
A swinging lever 21 operated by is engaged. The axis of motion of plunger 20A coincides with the axis of fuel injection nozzle 20. The injection nozzle 20 is of a stepped type, and the hole in the cylinder head 11 through which the fuel injection nozzle 20 extends has a clamp (not shown) between the step in this hole and the step of the fuel injection nozzle 20.
It has a complementary shape to the fuel injection nozzle 20 so as to be gas-tightly sealed by the fuel injection nozzle 20. The step in this hole must be able to withstand the axial thrust applied to plunger 20A during clamp loading and fueling. In addition to the passage 16, a cooling passage is also provided in the cylinder head 11. Furthermore, since the fuel injection nozzle 20 is located approximately in the middle of the poppet valve 17, the cylinder head 11
It has become relatively weak around here. In larger engines, it is possible to provide a step in the bore with sufficient support to withstand the clamping load and axial thrust applied to the plunger. However, in the case of small-sized engines, it has been difficult in the past to provide support for the stepped portions, and the present invention was made to solve this problem.

In FIG. 2, parts common to those in FIG. 1 are given the same numbers. Body 1 of fuel pump 19
A lateral protrusion 22 is formed at 9A, and a fuel injection nozzle 20 is provided in this protrusion 22. The axes of plunger 20A and nozzle 20 are mutually inclined. Body 19A of fuel pump 19
is formed with a surface 23 of complementary shape which engages a surface 24 formed in the cylinder head 11 at a location opposite the passageway 16. cylinder head 11
The surface 24 of the plunger 20 is connected to the plunger 20 by the cam 18A.
Absorbs the thrust applied by A. A clamping force also acts on this surface 24, but this clamping force is of a small type because the sealing method between the fuel injection nozzle 20 and the hole in which it is located is different from known ones. It has become a value.
Compression rings, which are formed in the body of the fuel injection nozzle and which engage with the inner wall of the hole in which the fuel injection nozzle is installed to provide a gas seal, are no longer used.

If this structure is used, the swing lever 21 can be omitted. This is because the axis of motion of plunger 20A intersects the axis of rotation of cam 18A. For example, if the axis of the plunger is made vertical, the two axes no longer intersect. For this purpose, the swing lever 2
It may be necessary to provide one or another camshaft.

FIG. 3 shows a first embodiment of the invention, in which the cylinder head 11 is provided with a stepped bore 25 extending towards the combustion chamber of the engine. A mounting surface 26 is formed on the cylinder head 11, and a first contact surface 27A of the pump body 27 having a complementary shape contacts this. A protrusion 28 is formed on the pump body 27, to which a fuel injection nozzle 29 is fixed by a known cap nut 30.

The protrusion 28 to which the pump body 27 and the cap nut 30 are attached is connected to the cap nut 30 and the hole 25.
A corrugated washer is used to seal between the cap nut 30 and the step. The axis (motion axis) of the fuel injection nozzle 29 is perpendicular to the first abutting surface 27A of the pump body 27, which has a complementary shape to the mounting surface 26. Pump body 2
7 incorporates a reciprocating plunger pump 31. Roller 32 forming part of pump 31
is operated by a cam provided on a camshaft (not shown) having a rotating shaft 33. The axis of the pump 31 is offset from the axis of the fuel injection nozzle 29, and the body 27 is bolted to and held by the cylinder head 11. The mounting surface 26 is formed at a distance from the stepped portion of the stepped hole 25 and has sufficient strength to withstand pumping force. However, the line of action of the cam forms an angle with the mounting surface 26. As a result, there is a force acting in a direction parallel to the mounting surface 26, and in order to absorb this force, the pump body 27
a dowel (or pin-like member) extending from the cylinder head 11 into a complementary shaped recess 34A;
(dowel) 34 is provided. This dowel 34
and the recessed portion 34A are respectively connected to the second contact surface 34C and the mounting surface 34 that absorb forces parallel to the mounting surface 26.
It forms B. This dowel 34 is attached to the mounting surface 26
It is preferable that the fuel injection nozzle has a cylindrical shape, which is perpendicular to the fuel injection nozzle 29 and parallel to the axis of the fuel injection nozzle 29. This second
A portion of the cylindrical surface, which is the abutment surface, engages with another mounting surface of the cylinder head. Also, a part of the cylinder head 11 is provided with a strut that corresponds to the shaft of the pump 31.
It may be set to 35. In this way, the forces generated by the action of the cam are applied to the cylinder head 11 at a location remote from the cylinder.

In FIG. 3, 36 is a control valve that controls the amount of fuel supplied to the engine by the pump. It is convenient to form a hole 36A forming a fuel passage in the support portion 35 and to provide a fuel passage for the control valve 36 in the dowel 34.

FIG. 4 shows in detail the various fuel passages within the pump body 27 and also shows a modification of FIG. 3. In this modification, there is no dowel 34,
Instead of this, a cylindrical projection 37 is formed in the pump body 27 and is provided with an interference fit in a cylindrical bore 38 formed in the cylinder head 11 and having a complementary shape. ing. and,
The protrusion 37 and the cylindrical hole 38 have a cylindrical second abutment surface 37A and a cylindrical mounting surface 38A, respectively, in order to absorb the forces resulting from the pumping action.
stipulates. A support portion 35 is formed in the cylinder head 11, the inner wall of which supports a protrusion 37 that receives a lateral load caused by the action of a cam on the roller 32. cap nut 30
A sealing ring 39 is provided to seal between the stepped hole 25 and the stepped hole 25 into which it is inserted. The air space between the projection 37 and the sealing ring 39 is supplied with fuel through a port 40 to fill the pump cylinder. A further sealing ring 41 is provided between the mounting surface 26 and the first abutment surface 27A of the pump body 27.

As described above, the compression ignition type engine fuel device of the present invention has the following features:
A body that can be attached to a cylinder head of an engine;
a fuel injection nozzle supported by the body and extending into the combustion space of the engine through a hole in the cylinder head; and an injection pump disposed within the body and having a reciprocatable plunger; , a first abutment surface extending perpendicularly to the axis of the combustion injection nozzle, and a second abutment surface extending parallel to the axis of the fuel injection nozzle; and a second abutment surface, the first abutment surface engages a mounting surface of a cylinder head of the engine, and the second abutment surface partially or completely engages a mounting surface of a cylinder head of the engine. Further, it engages another mounting surface, and the force component due to the reciprocating movement of the plunger during pumping is transmitted to the cylinder head via the first abutment surface and the second abutment surface, respectively. It is a feature.

Therefore, the clamping load of the injection nozzle and the axial load applied to the plunger are absorbed by the mounting surface of the cylinder head that engages the first and second abutting surfaces. For this reason, it is not necessary to provide a step in the bore through which the fuel injection nozzle extends in the cylinder head of a small internal combustion engine with sufficient support to withstand the clamping load and the axial thrust applied to the plunger. Therefore, even if it is a small internal combustion engine, the structure is simple and the durability is improved.

[Brief explanation of the drawing]

FIG. 1 is a vertical cross-sectional view of a known fuel system for an internal combustion engine, FIG. 2 is a vertical cross-sectional view of a fuel system for an internal combustion engine for explaining the present invention, and FIGS. 3 and 4 are respectively views of the present invention. FIG. 2 is a vertical cross-sectional view of a first embodiment and a second embodiment. 10... Engine, 11... Cylinder head, 13...
cylinder, 14...piston, 15...combustion chamber,
16... Passage, 17... Poppet valve, 18... Camshaft, 18A... Cam, 19... Fuel pump, 1
9A...Body, 20...Fuel injection nozzle, 20
A... Plunger, 21... Rocking lever, 22...
... protrusion, 23 ... surface, 24 ... surface, 25 ... stepped hole, 26 ... mounting surface, 27 ... pump body,
27A...first contact surface, 28...protrusion, 29...
...Fuel injection nozzle, 30...Cap nut, 3
2...Roller, 33...Rotating shaft, 34...Dowel,
34A... recess, 34C, 37A... second contact surface (cylindrical surface), 37... protrusion, 38... cylindrical hole.

Claims (1)

Claims: 1. A body 27 that can be mounted on a cylinder head 11 of an engine; a fuel injection nozzle 29 supported on said body and extending into the combustion space of the engine through a hole in said cylinder head; an injection pump 31 provided with a reciprocating plunger; the body has a first contact surface 27A extending perpendicularly to the axis of the fuel injection nozzle 29; Second contact surfaces 34C, 3 extending in parallel
7A, the operating axis of the plunger is inclined with respect to the first abutment surface and the second abutment surface, and the first abutment surface is engaged with the mounting surface 26 of the cylinder head of the engine. and the second abutting surface is partially or completely connected to a further mounting surface 34 of the cylinder head.
B, 38A, and the force component due to the reciprocating motion of the plunger during pump action is transmitted to the cylinder head via the first abutment surface and the second abutment surface, respectively. Compression ignition engine fuel system. 2. The compression ignition type engine fuel device according to claim 1, wherein the second contact surfaces 34C and 37A are cylindrical surfaces and extend from the first contact surface 27A. . 3 The fuel injection nozzle 29 is connected to the body 27
3. The compression ignition type engine fuel device according to claim 2, wherein the fuel device is supported by a protruding portion 37, and a part of the protruding portion is the cylindrical surface. 4. The fuel system for a compression ignition engine according to claim 2, wherein the cylindrical surface is formed by a dowel 34 located within a recess of the cylinder head 11. 5. The fuel system for a compression ignition engine according to claim 4, wherein the dowel 34 is hollow and forms a fuel passage.