JP3314436B2 - Fuel injection device and airtightness inspection method thereof - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuel injection device for a diesel engine and an airtightness inspection method therefor.

[0002]

2. Description of the Related Art As one type of fuel injection device for a diesel engine, a pump housing having a cam chamber and a bore communicating with the cam chamber, a cylinder fitted into and fixed to the bore of the pump housing, and a pump housing and a cylinder are defined. A fuel chamber formed and a pump chamber slidably fitted into the bore of the cylinder to communicate with the fuel chamber at the upper end of the bore of the cylinder. There is a fuel injection device of a type including a plunger for pressurizing fuel and an O-ring wound around a cylinder to separate the bore of a pump housing into a fuel space on a fuel chamber side and a lubricating oil space on a cam chamber side.

In this type of fuel injection device, the bore of the pump housing is divided into an upper fuel space and a lower lubricating oil space, and both spaces are sealed and separated by the O-ring.

[0004]

In the above-mentioned fuel injection device, the sealing performance of the O-ring is tested by filling the lubricating oil space in the bore of the pump housing with pressurized air and sealing it. It has been difficult to adopt a conventional leak inspection method, such as submerging in a water bath and examining air bubbles. This is because the pressurized air purged into the lubricating oil space leaks through the sliding gap between the bore of the cylinder and the plunger.

[0005] The present invention provides an airtightness inspection method for a fuel injection device which solves the difficulty of the sealing performance test of the O-ring separating the lubricating oil space and the fuel space of the fuel injection device. Its primary purpose is. A second object of the present invention is to provide a fuel injection device having a structure convenient for carrying out the above-mentioned airtightness inspection method.

[0006]

According to the present invention, there is provided a method for inspecting airtightness of a fuel injection device, comprising: a pump housing having a cam chamber and a bore communicating with the cam chamber; a cylinder fitted and fixed in the bore of the pump housing. A fuel chamber defined by the pump housing and the cylinder;
A pump chamber which is slidably fitted into the bore of the cylinder and is formed at the upper end of the bore of the cylinder so as to be able to communicate with the fuel chamber, and is reciprocally driven by a cam in the cam chamber to supply fuel in the pump chamber. A plunger to pressurize,
Sealing of the O-ring in a fuel injection device comprising an O-ring wound around the cylinder and separating the inside of the bore of the pump housing into a fuel space on the fuel chamber side and a lubricating oil space on the cam chamber side A method for inspecting airtightness of a fuel injection device for inspecting stop performance, wherein a liquid is filled in the lubricating oil space in a bore of the pump housing until a liquid level reaches between a lower end of the cylinder and the O-ring. Applying a gas pressure different from the fuel space to the remaining lubricating oil space, detecting gas leakage between the fuel space and the remaining lubricating oil space to determine the quality of the O-ring ,
The liquid is in front of the cylinder bore by the gas pressure.
Negligible flow in the sliding gap with the plunger
It is characterized by having a degree .

A fuel injection device according to the present invention includes a pump housing having a cam chamber and a bore communicating with the cam chamber, a cylinder fitted into and fixed to the bore of the pump housing, and a partition formed by the pump housing and the cylinder. And a pump chamber which is slidably fitted into the bore of the cylinder and is formed at the upper end of the bore of the cylinder so as to communicate with the fuel chamber, and is reciprocally driven by a cam in the cam chamber. A plunger for pressurizing the fuel in the pump chamber, and an O-ring wound around the cylinder to separate the inside of the bore of the pump housing into a fuel space on the fuel chamber side and a lubricating oil space on the cam chamber side. In the fuel injection device provided, the pump housing includes:
An airtightness inspection hole is provided between the lower end of the cylinder and the O-ring and communicated with the lubricating oil space, and the airtightness inspection hole has a liquid level in front of the lower end of the cylinder.
Pump the pump until it reaches between the O-rings.
Filling the lubricating oil space in the bore of the jing and the remaining
Apply a different gas pressure to the lubricating oil space than the fuel space,
Gas leakage between the fuel space and the remaining lubricating oil space
Used to detect and check the quality of the O-ring
It is characterized in that.

[0008]

In the airtightness inspection method for a fuel injection device according to the present invention, the liquid is filled into the bore of the pump housing until the liquid level reaches between the lower end of the cylinder and the O-ring, whereby the cylinder is sealed. The sliding gap between the bore and the plunger is filled with liquid, and a gas pressure difference is formed between the fuel space and the remaining lubricating oil space by sandwiching an O-ring. In this state, the fuel space and the remaining lubricating oil are formed. Detects gas leaks from space.

Theoretically, the liquid in the sliding gap between the bore of the cylinder and the plunger flows to the low pressure side due to the gas pressure difference between the two spaces, and the error due to this flow cannot be ignored. The sliding gap is minute, and the flow can be ignored due to the viscosity of the liquid. As a result, gas leakage between the two spaces can be considered only through the O-ring, and the sealing performance of the O-ring can be accurately inspected.

[0010] In the fuel injection device of the present invention, an airtightness inspection hole communicating with the lubricating oil space is located between the lower end of the cylinder and the O-ring and penetrates the pump housing. In this manner, when inspecting the sealing performance of the O-ring, the liquid can be quickly injected into the lubricating oil space from the hermetic inspection hole to the predetermined level through the hermetic inspection hole. Can be purged into the remaining lubricating oil space, and furthermore, a change in gas pressure in the remaining lubricating oil space can be easily detected through the airtight inspection hole, and the above-mentioned O-ring inspection can be performed very easily. It can be performed.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a fuel injection device and an airtightness inspection method thereof according to the present invention will be described below with reference to FIG. This fuel injection device has a pump housing 1. The pump housing 1 has a cam chamber 11, a bore 12 communicating with the cam chamber 11, and a fuel chamber 13 recessed at a predetermined position of the bore 12. The cylinder 2 is fitted and fixed in the bore 12 of the pump housing 1, and the plunger 3 is slidably fitted in the bore 21 of the cylinder 2. The upper end of the bore 21 of the cylinder 2 is partitioned by the plunger 3 and the pump chamber 22
The pump chamber 22 can communicate with the fuel chamber 13 of the pump housing 1 when the plunger 3 is lowered by a feed hole 23 provided through the cylinder 2.
The plunger 3 is reciprocated by the cam 4 in the cam chamber 11 to pressurize the fuel in the pump chamber 22. The O-ring 5, which is an essential part of the present embodiment, is wound around the cylinder 2 and separates the bore 12 of the pump housing 1 into a fuel space F on the fuel chamber 13 side and a lubricating oil space L on the cam chamber 11 side. I do. Further, an airtightness inspection hole 6, which is another essential part of the present embodiment, is provided in the pump housing 1 at a position between the lower end of the cylinder 2 and the O-ring 5 in the vertical direction in the figure, and penetrates the pump housing 1. Is in communication with

The details will be described below. Plunger 3
Reciprocates in the cylinder 2 as is well known, and the fuel chamber 13
Then, the fuel is sucked into the pump chamber 22 through the feed hole 23 of the cylinder 2, and the fuel is compressed and the delivery valve 7 is opened to feed the fuel to a nozzle (not shown).

The cylinder 2 has a flange 24 at an upper end and a fitting portion 25 at an intermediate portion. The lower end of the cylinder 2 is formed to have a smaller diameter than the fitting portion 25. An element holder hole 27 larger in diameter than the bore 21 and communicating with the bore 21 is formed in the upper end portion of the cylinder 2 along the axis from the upper end surface of the cylinder 2.
After the sleeve 81 and the delivery valve 7 are inserted,
The valve holder 8 is screwed.

The delivery valve 7 is substantially fitted into the valve holder 8 and the element holder hole 2 of the cylinder 2 is
The valve holder 8 also serves as a joint connected to a fuel pumping pipe (not shown) connected to a nozzle (not shown). The pump housing 1 has a flat upper end surface and a bore 1 having a constant inside diameter that penetrates to the upper end surface.
Two. A fitting portion 25 of the cylinder 2 is fitted into the upper end portion of the bore 12 of the pump housing 1 with a small gap, and the lower end surface of the flange 24 is in contact with the upper end surface of the pump housing 1 via a shim. In this state, it is fixed to the pump housing 1 by stud bolts 15 and nuts 16.

A lower surface of the plunger 3 is formed with a two-sided shaft portion which engages with the control sleeve 90.
Teeth are formed on the outer circumference of the sleeve 90, and a rack (not shown) meshes with the teeth. The rack is connected to a governor (not shown), and the control sleeve 90 is rotated in accordance with the operation of the rack, whereby the plunger 3 is rotated relative to the cylinder 2 to control the fuel discharge amount.

The tappet 92 converts the rotation of the camshaft 41 into a reciprocating motion and transmits the reciprocating motion to the plunger 3.
The pump housing 1 is slidably fitted in the bore 12, and the lower end thereof is in contact with the cam surface of the cam shaft 41. A lower spring sheet 94 is in contact with the upper end of the tappet 92, and the lower spring sheet 94 is urged by the lower end of the spring 95 to urge the tappet 92 downward. Further, the lower spring sheet 94 connects the lower end of the plunger 3 to the tappet 92.

The upper end of the spring 95 is engaged with a ring-shaped upper spring sheet 96 fitted on the outer periphery of the control sleeve 90, and the upper spring sheet 96 is provided.
Is fixed to the housing 1. An O-ring 51 is provided above the fuel chamber 13 to seal a fuel space F in the bore 12 of the pump housing 1 from the outside. In the fuel injection device of the present embodiment configured as described above, the lubricating oil space L is filled with lubricating oil at the time of use, and the airtight inspection hole 6 is used with a blind plug. That is, when the plunger 3 moves down, a communication hole (not shown) inside the plunger 3 is moved from the fuel chamber 13 through the feed hole 23 to the pump chamber 22.
And the fuel is sucked into the pump chamber 22. When the plunger 3 moves upward and the communication hole in the plunger 3 cuts off the communication between the feed hole 23 and the pump chamber 22, the fuel in the pump chamber 22 is compressed, and when a predetermined pressure is reached, the fuel is sent to the nozzle through the delivery valve 7. Can be

Next, a method for judging the quality of the sealing performance of the O-ring 5 will be described. First, a hole for communicating the lubricating oil space L with the outside, for example, a lubricating oil injection hole (not shown) is blind-plugged. However, a pipe joint is screwed into the airtightness inspection hole 6, and lubricating oil is supplied to the bore 12 of the pump housing 1 through the pipe joint until the oil level reaches between the lower end of the cylinder 2 and the O-ring 5. Lubricating oil space L
Inject into However, in this embodiment, the fuel injection device is arranged in the state shown in the figure, and after lubricating oil is injected to some extent, the lubricating oil pipe (not shown) is removed from the pipe joint, so that the lubricating oil is leaked from the airtightness inspection hole 6. The oil flows down to the outside so that the liquid level comes to the lower end of the airtight inspection hole 6.

Next, a pressure pipe is connected to the pipe joint, and a compressor or a high-pressure air tank is connected through the pressure pipe. Next, the valve provided in the middle of this pressure pipe is opened, and the lubricating oil space L
A predetermined air pressure is applied to the remaining space, and then the valve is closed. A pressure gauge (not shown) is mounted on the pressure pipe at a position closer to the airtightness inspection hole 6 than the valve, and the pressure gauge indicates a reading P1 immediately after the valve is closed and a reading P2 after a predetermined time. If the difference ΔP exceeds the predetermined threshold value Pth, the pressurized air in the lubricating oil space L
Leaked into the fuel space F through the gap
-It is determined that the ring 5 is defective.

After the inspection, the airtight inspection hole 6 is plugged in a usual manner. That is, according to this embodiment, lubricating oil is sealed in the lubricating oil space L, and the lubricating oil
O with the sliding gap between the plunger 1 and the plunger 3 sealed.
-Since the gas leak through the ring 5 is detected, the airtightness inspection by the normal gas purge can be performed irrespective of the existence of the sliding gap.

According to the above embodiment, the airtightness inspection hole 5 is located between the lower end of the cylinder 2 and the O-ring 5 in the axial direction and penetrates through the pump housing 1.
When inspecting the sealing performance of the O-ring 5, lubricating oil can be quickly injected from the hermetic inspection hole, and a pressurized air pipe is connected to the same hermetic inspection hole 6 so that the upper part of the lubricating oil space L (I.e., the remaining lubricating oil space) can be purged with pressurized air, and the pressurized air can be brought into contact with the O-ring 5, which has the advantage that the inspection can be performed efficiently. Further, the airtight inspection hole 6 can also serve as a normal lubricating oil inlet / outlet for injecting lubricating oil into the bore of the pump housing 1.

FIGS. 2 and 3 show examples of blind plugs in the airtight inspection hole 6. FIG. In FIG. 2, the blind plug 61 is sealed with a gasket 62 interposed therebetween, and in FIG.
4 is wound and sealed. In the above description, the pressurized air is purged to the remaining lubricating oil space L side to check the pressure change. However, the purged fuel injection device may be immersed in liquid to check for bubbles.

Further, a special gas component may be mixed in the pressurized air, and the special gas component in the air on the fuel space F side may be detected electronically or chemically. Conversely, the remaining lubricating oil space L may be purged with decompressed air to check the increase in pressure. Further, the fuel space F
It is also possible to purge the pressurized air to the side, and to detect a decrease in the purge pressure due to a leak through the O-ring 5.

In the above embodiment, the fuel chamber 13 is formed not only by forming the bore of the pump housing 1 in a concave shape but also by forming the bore.
The outer peripheral surface of the cylinder 2 may be formed to be concave.

[Brief description of the drawings]

FIG. 1 is a sectional front view of a fuel injection pump to which an embodiment of the present invention is applied.

FIG. 2 is a sectional view showing an example of a blind plug of an airtightness inspection hole.

FIG. 3 is a cross-sectional view showing another example of a blind plug of an airtightness inspection hole.

[Explanation of symbols]

 1 pump housing, 2 cylinders, 3 plungers, 5 O-rings, 6 airtightness inspection holes, 11 cam chambers, 12 pump housing bores, 13 fuel chambers, 21 cylinder bores 22 pump chambers F fuel space, L lubricating oil space.

Claims (2)

(57) [Claims] A pump housing having a cam chamber and a bore communicating with the cam chamber; a cylinder fitted into and fixed to the bore of the pump housing; a fuel chamber defined by the pump housing and the cylinder; A pump chamber which is slidably fitted into the bore of the cylinder and is formed at the upper end of the bore of the cylinder so as to be able to communicate with the fuel chamber, and is reciprocally driven by a cam in the cam chamber to supply fuel in the pump chamber. A fuel injection device comprising: a plunger to be pressurized; and an O-ring wound around the cylinder to separate the bore of the pump housing into a fuel space on the fuel chamber side and a lubricating oil space on the cam chamber side. The pump housing is connected to the lower end of the cylinder and the O
An airtight inspection hole which is located between the ring and the lubricating oil space and is penetrated therethrough , wherein the airtight inspection hole has a liquid level between the lower end of the cylinder and the O.
Pump housing until it reaches between
Filling the lubricating oil space in the bore of the
A gas pressure different from that of the fuel space is applied to the oil space,
Detects gas leaks between the fuel space and the remaining lubricating oil space
A fuel injection device for inspecting the quality of the O-ring . 2. A pump housing having a cam chamber and a bore communicating with the cam chamber, a cylinder fitted into and fixed to the bore of the pump housing, a fuel chamber defined by the pump housing and the cylinder, A pump chamber which is slidably fitted into the bore of the cylinder and is formed at the upper end of the bore of the cylinder so as to communicate with the fuel chamber, and is reciprocally driven by a cam in the cam chamber to supply fuel in the pump chamber. The fuel injection device includes a plunger for pressurizing, and an O-ring wound around the cylinder to separate a bore of the pump housing into a fuel space on the fuel chamber side and a lubricating oil space on the cam chamber side. An airtightness inspection method for a fuel injection device for inspecting a sealing performance of an O-ring, wherein a liquid level is defined between a lower end of the cylinder and the O-ring. Fill the lubricating oil space in the bore of the pump housing until the pressure reaches the pressure, apply a gas pressure different from the fuel space to the remaining lubricating oil space, and apply a gas pressure between the fuel space and the remaining lubricating oil space. with the determining the quality of the O- ring by detecting the leakage of gas, the liquid, the gas pressure
Therefore, sliding between the cylinder bore and the plunger
An airtightness inspection method for a fuel injection device, characterized in that the airtightness has a viscosity such that flow in a gap is negligible .