JPH10131860A - Fuel feeder for internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To restrain resonance of a bellows of a fuel force-feeding means provided with the bellows by imparting damper action to the outside of the bellows. SOLUTION: A fuel feeder for an internal combustion engine is provided with a fuel force-feeding means having a fuel chamber formed and supplied with fuel and a bellows 29 with one end fixed to the outside of the fuel chamber or in such a way as to form part of the fuel chamber and with the other end provided movably to close so that fuel does not leak to the outside and sucking/ discharging fuel in association with the expansion of the bellows 29, and resonance restraining means 18e, 18h, 18i for applying a fluid to at least part of the outer surface of the bellows 29 or dipping to restrain resonance.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a fuel supply device for an internal combustion machine.

[0002]

2. Description of the Related Art As a high-pressure fuel supply device for feeding high-pressure fuel to an internal combustion engine, there is a compression-type high-pressure fuel pump 1 as shown in FIG. The high-pressure fuel pump 1 draws fuel from a suction port 1a by reciprocating a plunger 3 in a pump cylinder 2 by a built-in spring and a cam 6 rotationally driven by an internal combustion engine, compresses the fuel, and compresses the discharge port 1b.
Discharge from.

A bellows 4 is provided to separate and seal the inside (fuel section) of the fuel pump 1 and the cam 6 side (plunger driving section). The bellows 4 is provided between the pump cylinder 2 and the plunger 3. The fuel leaked from the sliding portion is prevented from leaking to the outside of the pump and returned to the drain tank, and the lubricating oil (engine oil) filling the outside of the plunger 3 is mixed with the fuel in the pump cylinder 2. Is preventing that.

When fuel leaking from a sliding portion between the pump cylinder 2 and the plunger 3 mixes with the lubricating oil, the viscosity of the lubricating oil decreases, and the rotating parts of the internal combustion engine, such as the crankshaft, camshaft, connecting rod, etc. Cause burn-in.
Also, if lubricating oil is mixed into the fuel inside the fuel pump 1,
The viscosity of the fuel increases, which causes clogging of the fuel injection valve. For this reason, the bellows 4 allows the fuel pump 1
And the cam 6 side are divided and sealed to prevent mutual mixing of fuel and lubricating oil. The bellows 4 is formed of a metal plate in order to require gasoline resistance and durability.

[0005]

The bellows 4 is a spring system, and resonance occurs due to forced vibration by the cam 6.
When the resonance occurs, the bellows 4 has a resonance magnification of approximately twice or more (displacement at resonance / design displacement). In the worst case, the bellows 4 breaks due to exceeding the allowable compression limit or exceeding the fatigue limit. May occur. In order to suppress the resonance of the bellows 4, it is customary to generally raise the natural frequency of the system to remove it from the rotation range of the cam 6, that is, the normal rotation range of the internal combustion engine.

However, raising the natural frequency of the bellows 4 means reducing the number of bellows peaks. Reducing the number of peaks of the bellows 4 results in increasing the amount of displacement per peak. Further, depending on the profile of the cam 6, higher-order (third-order or higher) high-frequency waves may be introduced, and there is a problem that the possibility of breakage of the bellows 4 exceeds the allowable displacement and increases.

As another means for suppressing the resonance of the bellows 4, a method of reducing the resonance magnification by a damper can be considered. That is, it is conceivable that the fuel leaked from between the pump cylinder 2 and the plunger 3 is stored in the bellows 4 to obtain a damper effect with the fuel. However, the fuel leaking from between the pump cylinder 2 and the plunger 3 is at high pressure, while the pressure inside the bellows 4 is low, so that a small amount of fuel leaking into the bellows 4
Evaporates instantly. Therefore, the inside of the bellows 4 is in a gas-liquid mixed state, and the fuel as the liquid hardly accumulates, and the damper effect by the fuel cannot be expected. Also,
If, for example, a check valve or the like is provided on the drain port side of the bellows 4 to store the fuel, the pressure inside the bellows 4 will increase, which will adversely affect the bellows 4.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned point, and a fuel for an internal combustion engine in which resonance of a bellows is suppressed by imparting a damper function outside the bellows of a fuel pressure feeding means having a bellows. It is intended to provide a supply device.

[0009]

According to the present invention, a fuel chamber to which fuel is supplied is formed, and the fuel chamber is formed outside the fuel chamber or as a part of the combustion chamber. One end is fixed, the other end is provided so as to be movable, has a bellows for hermetically sealing so that fuel does not leak to the outside, and a fuel pumping means for sucking and discharging fuel as the bellows expands and contracts. In this configuration, a fluid is applied or immersed in a part of the outer surface of the bellows to prevent resonance, thereby providing a resonance preventing means.

[0010] By applying or dipping the liquid on the outer surface of the bellows, the liquid is interposed between the peaks, and when the bellows is compressed, the viscosity of the liquid gives a damper action to attenuate the vibration. Thereby, resonance of the bellows is suppressed. The bellows is preferably a metal bellows in terms of gasoline resistance and durability, and the liquid to be applied or dipped on the outer surface is a liquid having a higher viscosity than the fuel, for example, an engine lubricating oil. preferable.

The fuel pumping means includes a bellows forming a volume chamber and sucking and discharging the fuel by expansion and contraction of the bellows, and a fuel sucking and discharging by sliding back and forth in the housing. One end of the bellows is fixed to the housing, the other end is fixed to be driven together with the plunger, and the bellows is configured to seal the sliding surface between the housing and the plunger from the outside. Some have been done.

The resonance preventing means is preferably an injection means (oil jet) for injecting a highly viscous fluid to the bellows, or a cap means for storing a highly viscous fluid therein to cover the periphery of the bellows of the fuel pumping means. . In claim 2, the fuel pumping means has a plunger for reciprocating in a housing forming at least a part of the fuel chamber to suck and discharge fuel, and one end of the bellows is connected to the housing. The other end is fixed so as to be driven together with the plunger, and the bellows is configured to seal a sliding surface between the housing and the plunger from the outside.

The plunger slides back and forth in the housing to suck and discharge fuel. The bellows has one end fixed to the housing and the other end fixed to be driven together with the plunger, and seals a sliding surface between the housing and the plunger from the outside. The plunger type fuel pumping means can obtain a high discharge pressure, and is suitable for a fuel supply device requiring a high pressure.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The embodiments of the present invention will be described below by way of examples. (Embodiment 1) As shown in FIG. 1 and FIG.
(For example, 4-cycle spark ignition type direct injection internal combustion engine)
A fuel supply device 15 is mounted on the upper rear end of the cylinder head 11. The fuel supply device 15 includes a pump drive mechanism 16 and a high-pressure fuel pump 17 mounted on and driven by the pump drive mechanism 16. The pump drive mechanism 16 is connected to and driven by a camshaft (not shown) of a valve mechanism housed in the cylinder head 11, and is driven by a high-pressure fuel pump (hereinafter, referred to as “fuel pump”).
17 is driven. The fuel pump 17 is a compression type fuel pump that sucks, compresses, and discharges fuel by reciprocating motion of a plunger. This fuel pump is disclosed in
It is suitable for use in a fuel supply device for a direct injection internal combustion engine as disclosed in Japanese Patent No. 3134.

As shown in FIG. 3, a camshaft 19 is housed in a pump cam case 18 of the drive mechanism 16.
The camshaft 19 has journals 19a, 19b at both ends.
However, a cam 19c is provided at the center. The journals 19a and 19b at both ends are the bearings 1 of the pump cam case 18.
It is rotatably supported by 8a and 18b. The camshaft 19 has a base end 19d connected to a camshaft of the valve mechanism via a coupling 20. One side of the pump cam case 18 has a mounting hole 1 facing the cam 19c.
8c is provided.

As shown in FIGS. 2 and 4, a boss 18d is provided along the camshaft 19 on the upper part of the pump cam case 18.
Is provided, and an oil passage 18e is provided substantially in the center in the longitudinal direction (along the camshaft 19). Further, the boss 18d has an oil passage 1 extending obliquely downward and orthogonal to the passage 18e, and each upper part communicating with the passage 18e.
8f, 18g and 18h are provided. Oil passage 1
8e, the base end side is communicated with an oil gallery (not shown) provided in the cylinder head 11, and the front end is closed. The upper ends of the oil passages 18f to 18h are closed. The lower ends of the oil passages 18f and 18h on both sides are open to the cam surface of the cam 19c via a passage (not shown). A lower end 18i of the central oil passage 18g is formed as an injection nozzle (hereinafter, referred to as a "nozzle 18i") having a diameter smaller than that of the oil passage 18g and opened toward the front of the bellows 29 of the fuel pump 17.

FIG. 5 shows the fuel pump 17. In the fuel pump 17, a pump cylinder 24 is mounted via a holder 23 in a pump housing 22, and a plunger 25 is fitted into the pump cylinder 24 so as to be slidable in the axial direction. A leaf valve 26 is interposed between the base end of the pump cylinder 24 and the pump housing 22.
At the base end of the plunger 25, a pump chamber 25a is provided. The spring 27 includes the plunger 25 and the leaf valve 2
6, one end of which is inserted into the pump chamber 25a and pressed against the end face of the pump chamber 25a, and the other end is pressed against the leaf valve 26.

An annular holder 28 is mounted near the end of the plunger 25 and fixed by welding. This holder 2
8 has substantially the same diameter as the outer diameter of the holder 23 and faces the holder 23. Bellows 29 is holder 23
, And concentrically surrounding the plunger 25, both ends of which are brazed to the opposite end faces of the holders 23 and 28 and fixed in a liquid-tight manner.
The bellows 29 liquid-tightly defines the inside of the pump (plunger 25) and the driving side (cam 19c side) outside the pump. The bellows 29 is formed of a thin metal plate.

A suction port 22a, a discharge port 22b, and a drain port 22c are provided on an end surface of the pump housing 22, and a pump chamber 25a is provided through a leaf valve 26.
Can be communicated with. The leaf valve 26 opens and closes in response to the movement of the plunger 25, that is, when the plunger 25 moves to the left in the drawing, the suction port 22a opens, the discharge port 22b closes to inhale fuel, and moves to the right. When moving, the intake port 22a side closes and the discharge port 22b side opens to discharge high-pressure fuel.

In the fuel pump 17, a front portion 22A of the pump housing 22 is fitted and mounted in a mounting hole 18c of a pump cam case 18 as shown in FIGS. In this state, the tip surface 25b of the plunger 25 is
c. And the nozzle 1 of the oil passage 18g
8i faces the vicinity of the front end of the bellows 29 from an obliquely upper position, and sprays an oil jet. Further, the suction port 22a of the fuel pump 17 is connected to a fuel passage, and the discharge port 22b is connected to a fuel injection valve (not shown) of the internal combustion engine.

The operation will be described below. As shown in FIG. 3, the camshaft 19 is driven to rotate by a camshaft of a valve mechanism provided in the cylinder head 11. Cam 19
c reciprocally drives the plunger 25 in cooperation with the spring 27 as it rotates, and the pump chamber 25
a, and the compressed high-pressure fuel is discharged into discharge port 2
Discharge from 2b. Then, the bellows 29 expands and contracts according to the reciprocating motion of the plunger 25.

On the other hand, with the operation of the internal combustion engine 10, the oil gallery on the cylinder head 11 side passes through the oil passage 18e of the pump cam case 18 shown in FIG.
Oil is supplied to 8f to 18h. Oil passage 18
The oil supplied to f and 18h is supplied to the sliding surface between the cam 19c and the distal end surface 25b of the plunger 25 to lubricate the sliding surfaces of both.

The oil supplied to the oil passage 18g is
It is sprayed from the nozzle 18i and sprayed near the front end of the bellows 29. As a result, the oil is bellows 29
Adhere between the mountains and flow. The injected oil is supplied to the bellows 29 and the tip 2 of the pump housing 22.
2A, and also enters between the peaks of the bellows 29 inside the tip portion 22A. Thereby, oil adheres between the peaks of the bellows 29. And
The oil is applied to the bellows 29 thickly. As a result, the oil adheres between the peaks of the bellows 29, so that the damper action due to the viscosity of the oil occurs, and the resonance is largely suppressed. (Embodiment 2) FIG. 6 shows a configuration in which a fuel pump 17 is disposed below a camshaft 19 of a pump cam case 18. As shown in FIG.
By arranging the plunger 25 and the bellows 29 below, the oil lubricating the cam 19c and the tip end surface 25b of the plunger 25 is stored in the pump cam case 18 to form an oil tank 31. Bellows 29
Is soaked. As a result, the damping action is generated by the viscosity of the oil, and the resonance of the bellows 29 is suppressed very well.

FIG. 8 shows an example of the rotational speed of the internal combustion engine (corresponding to twice the rotational speed of the camshaft 19) and the resonance magnification of the bellows 29. 8, the solid line indicates the resonance magnification of the bellows to which the present invention is applied, and the dotted line indicates the resonance magnification of the conventional bellows. As is apparent from this figure, in the case of the conventional example shown by the dotted line, the resonance magnification reaches about twice that of the low rotation (about 1000 rpm) when the engine speed is high (about 6000 to 7000 rpm). On the other hand, when the present invention is applied, it is about 1.2 times, and it is clear that resonance is extremely effectively suppressed.

According to the second embodiment, there is no need to particularly provide the oil passage 18g facing the bellows 29 as in the first embodiment, and the structure of the oil passage of the pump cam case 18 can be simplified. . (Embodiment 3) FIG. 7 is applied to a case where the layout shown in FIG. 6 is difficult. That is, the cap 32 is attached to the tip portion 22A of the pump housing 22 of the fuel pump 17 to surround the bellows 29. A nozzle 18i of an oil passage 18g is provided above the cap 32.
A notch 32a is provided and opened. This allows
The oil sprayed from the nozzle 18i is sprayed to the front end of the bellows 29 through the notch 32a of the cap 32 and accumulates in the cap 32. Then, the bellows 29 is immersed in the oil accumulated in the cap 32. As a result, the bellows 29 as in the case of the second embodiment
Is favorably suppressed.

In the first embodiment, the bellows 29 is applied to the outer surface. In the second and third embodiments, the entire bellows is immersed in oil. For example, highly viscous grease is applied. Is also good. Further, the liquid applied to or immersed in the bellows 29 may be any liquid having a higher viscosity than fuel (gasoline), and is not limited to engine oil. However, it is preferable to use the engine oil used as the lubricating oil in the internal combustion engine because the same oil supply system can be used.

[0027]

As described above, according to the present invention, the damper function of the bellows of the fuel pump can be obtained with a very simple structure, the resonance of the bellows can be suppressed very effectively, and the durability can be improved. The performance can be greatly improved. In addition, the reciprocating movement of the plunger
Since discharge is performed, the discharged fuel can be made high pressure with a simple structure, and can be effectively applied particularly to a fuel supply system that requires high pressure fuel such as a direct injection internal combustion engine.

[Brief description of the drawings]

FIG. 1 is a side view of a cylinder head equipped with a fuel supply device according to the present invention.

FIG. 2 is a side view of the fuel supply device of FIG.

FIG. 3 is a cross-sectional view of a main part along an arrow line III-III in FIG. 2;

FIG. 4 is a sectional view taken along a line IV-IV in FIG. 2;

FIG. 5 is a sectional view of a compression high-pressure fuel pump of the fuel supply device shown in FIG.

FIG. 6 is an explanatory diagram for providing a damper to a bellows of a high-pressure fuel pump according to a second embodiment of the present invention.

FIG. 7 is an explanatory diagram for providing a damper to a bellows of a high-pressure fuel pump according to a third embodiment of the present invention.

FIG. 8 is a diagram illustrating a relationship between an engine speed and a resonance magnification of a bellows in a high-pressure fuel pump of a fuel supply device to which the present invention is applied.

FIG. 9 is a sectional view of a conventional compression-type high-pressure fuel pump.

[Explanation of symbols]

 Reference Signs List 10 internal combustion engine 11 cylinder head 15 fuel supply device 16 pump drive mechanism 17 high-pressure fuel pump 18 pump cam case 18d boss 18e to 18g oil passage 18i nozzle 19 camshaft 19c cam 20 coupling 22 pump housing 23, 28 holder 24 pump cylinder 25 Plunger 26 Leaf valve 27 Spring 29 Bellows 31 Oil tank 32 Cap

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Ren Hirako 5-33-8 Shiba, Minato-ku, Tokyo Inside Mitsubishi Motors Corporation (72) Inventor Shigeo Yamamoto 5-33-8 Shiba, Minato-ku, Tokyo Mitsubishi (72) Inventor Hiroshi Tanada 5-33-8 Shiba, Minato-ku, Tokyo Mitsubishi Motors Corporation

Claims (2)

[Claims] 1. A fuel chamber to which fuel is supplied is formed, one end is fixed so as to form an outside of the fuel chamber or a part of the combustion chamber, and the other end is provided so as to be movable, so that fuel is provided. Has a bellows that seals to prevent leakage to the outside,
An internal combustion system comprising: a fuel pumping means for sucking and discharging fuel as the bellows expands and contracts; and a resonance preventing means for applying or immersing a fluid to at least a part of the outer surface of the bellows to prevent resonance. Engine fuel supply device. 2. The fuel pumping means includes a plunger for reciprocating within a housing forming at least a part of the fuel chamber to suck and discharge fuel, and one end of the bellows is connected to the housing. 2. The internal combustion engine according to claim 1, wherein the other end is fixed to be driven together with the plunger, and the bellows is configured to seal a sliding surface between the housing and the plunger from the outside. Engine fuel supply device.