JPS6329872Y2 - - Google Patents

Description

[Detailed Description of the Invention] (Industrial Field of Application) This invention relates to a diesel fuel injection device, and particularly to a valve device for controlling the supply of high-pressure fuel that has been pressure-accumulated.

(Prior Art) A pressure accumulation type fuel injection device is, for example, as shown in FIG. is stored in the pressure accumulator 5, and the high-pressure fuel in the pressure accumulator 5 is intermittently discharged from the pressure accumulator 5 into an automatic valve type by opening and closing the valve device 7 via the cam 6 using the driving force from the engine. The fuel is sent to the fuel injection valve 8. In this system, the high pressure fuel sent to the fuel injection valve 8 is injected into the engine combustion chamber by lifting the needle valve of the fuel injection valve 8.

A major drawback of such a pressure accumulation type fuel injection device is a problem with the valve device that controls the supply of fuel. Therefore, a valve device as disclosed in Japanese Patent Application Laid-Open No. 55-5419 was proposed.

In this valve device, the pressure in the plunger chamber 18 increases as the plunger 9 rises, and the push rod control valve 15 is displaced by the pressure against the spring 16.
As a result, the on-off control valve 13 is pushed, the on-off control valve 13 is displaced against the spring 14, and the through hole is opened.
It supplies high-pressure fuel to the fuel injection valve, and when the plunger 9 is cut off and the pressure inside the plunger chamber 18 decreases, the opening/closing control valve 13 is activated by the spring 14.
The valve seats on the valve seat and fuel supply ends.

(Problem to be solved by the invention) However, the upper valve chamber 2 is always filled with high-pressure fuel, and the pressure is applied in the direction to close the opening/closing control valve 13. Therefore, the opening/closing control valve 13
As a result, the valve is energized by the resultant force of force and pressure (high-pressure fuel), and a large force is required to open the valve.In order to cope with this force, the hydraulic pressure from the plunger must also be increased. Ta.

Therefore, an object of this invention is to provide an on-off valve that is not affected by high-pressure fuel from a pressure accumulator.

(Means for solving the problem) The gist is that the large-diameter hole 23a connected to the fuel outlet hole 24b connected to the fuel injection valve 8 and the fuel inlet hole 24a connected to the pressure accumulator 5 are opened. A fuel passage hole 23 is formed concentrically in communication with a small-diameter hole 23b, and has a valve seat 25 at a stepped portion of the communication portion, and has a valve portion 21a at one end and approximately the same size as the small-diameter hole 23b at the other end. The piston 21c has a diameter of , and has a connecting rod part 21b in the middle, and the connecting rod part 21b is formed to be smaller than the diameter of the piston 21c.
When the on-off valve 21 is inserted into the fuel passage hole 23 and its valve portion 21a is seated on the valve seat 25 by the spring 26, the fuel inlet hole 24a is opened.
The fuel pressure is applied to the valve portion 21a and the piston 21c so as to offset each other, and further includes a pressure generator 27 that can apply pressure to the piston 21c of the on-off valve 21. The on-off valve 21 is lifted by hydraulic pressure against the force of the spring 26, thereby communicating the fuel inlet hole 24a and the fuel outlet hole 24b.

(Function) Therefore, the pressure of the high-pressure fuel in the pressure accumulator is applied below the valve part of the on-off valve and above the piston, but since the directions in which the pressure is applied are opposite to each other, they are canceled out and the opening/closing is performed. As a result, the on-off valve is biased only by the force of the spring without any influence on the valve, so that the hydraulic pressure applied to the piston only needs to resist the spring.
The hydraulic pressure of the opening/closing valve can be reduced, and the above-mentioned problem can be achieved.

(Example) Hereinafter, an example of this invention will be described with reference to the drawings.

In FIG. 2, a sectional view of the valve device 7 of this invention is shown, and the valve device 7 is roughly divided into an on-off valve 21 and a pressure generating device 27 for displacing (opening and closing) the on-off valve 21. 21 has a poppet-shaped valve part 21a formed at one end and a piston 21c at the other end, and the valve part 21a and the piston 21c
The connecting rod 22b between the piston 21c and the piston 21c is formed to be smaller in diameter than the piston 21c. The on-off valve 21 is disposed as described below in a fuel passage 23 which forms a part of a high-pressure oil passage 24 that communicates a pressure accumulator (not shown) with a fuel injection valve.

The fuel passage hole 23 consists of a large-diameter hole 23a formed in the body 22 and a small-diameter hole 23b communicating with the large-diameter hole 23a, and the large-diameter hole 23a has a fuel outlet hole 24b for sending fuel to the fuel injection valve. A fuel inlet hole 24a that receives fuel from a pressure accumulator is connected to each of the small-diameter holes 23b in a direction perpendicular to the small-diameter holes 23b.

The small diameter hole 23b has approximately the same diameter as the piston 21c described above, and is communicated with a hole through which pressurized oil is supplied from a pressure generating device 27 described below.

The on-off valve 21 described above has its piston 21c inserted into the small-diameter hole 23b, and the valve portion 21a is attached to the valve seat 25 by a spring 26, which is formed at a step between the large-diameter hole 23a and the small-diameter hole 23b. It is energized and seated. Therefore, the through hole 23 is closed to the on-off valve 21.

The pressure generating device 27 has a plunger 29 that fits in a plunger barrel 28 in an oil-tight and slidable manner, and the plunger 29 is connected to an engine (not shown).
The cam 30 is rotated in synchronization with the cam 30 to reciprocate via the tappet 31, and the pressure generated is controlled by the reed 32 formed in the head and the suction/discharge hole 33 formed in the barrel 28.

The plunger 29 is connected to the control sleeve 34
The injection amount control force is transmitted from the control rack 35 through the control rack 35 to rotate the plunger 29, and the period of pressure supplied to the plunger chamber 36 provided between the plunger 29 and the piston 21c of the on-off valve 21 is controlled. be done.

In such a pressure generating device 27, the tappet 31 is displaced against the spring 37 by the cam 30 which is rotated in synchronization with the engine, and the plunger 2
9 is lifted and closes the suction/discharge hole 33, the pressure inside the plunger chamber 36 increases, and compression continues until the suction/discharge hole 33 is cut off.As a result, the pressure applied to the lower end surface of the piston 21c causes the spring 26 to
Against this, the on-off valve 21 is switched from closed to open, and the pressurized oil in the high-pressure oil passage 24 is sent to the fuel injection valve through the through hole 23, pushes up the needle valve, and is injected into the combustion chamber.

This fuel injection continues until the plunger 29 of the pressure generating device 27 is cut off, at which point the pressure in the plunger chamber 36 drops suddenly and the injection ends.

In this way, since the large diameter hole 23a of the through hole 23 is connected to the injection valve, the valve portion 23a of the on-off valve 21
1a is not subjected to high pressure, and high pressure fuel is supplied to the piston 21c below the valve portion 21a of the on-off valve 21.
However, the directions of the pressures are opposite to each other, so that they cancel each other out and have no effect on the on-off valve, and the on-off valve is biased only by the force of the spring 26.
In order to open the on-off valve, it is sufficient if the pressure is always sufficient to resist the spring force.

In FIG. 3, another embodiment of the invention is shown. This embodiment differs from the previous embodiment in that the valve section 26b of the on-off valve 21 is
A suction collar 21d is installed near 1a. Therefore, when the on-off valve 21 closes, the suction collar 21d helps reduce the pressure in the oil feed path up to the injection valve, and prevents problems such as secondary injection. The other points are the same as those of the previous embodiment, so the same numbers are given and explanations are omitted.

(Effects of the invention) As explained above, according to this invention, the switching operation of high-pressure fuel to the fuel injection valve is performed with sufficient force from the pressure generator to resist the spring force displacing the on-off valve. This is sufficient, and the pressure generating device can also be made smaller.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of a pressure accumulation type fuel injection device, FIG. 2 is a sectional view of a valve device of this invention, and FIG. 3 is a sectional view of a valve device of another embodiment of this invention. 21... Opening/closing valve, 21a... Valve section, 21b...
Connecting rod, 21c...Piston, 23...Through hole, 23
a...Large diameter hole, 23b...Small diameter hole, 26...
Spring, 27...pressure generating device.

Claims (1)

[Scope of utility model registration request] A large diameter hole 23a connected to a fuel outlet hole 24b connected to the fuel injection valve 8 and a small diameter hole 23b connected to the fuel inlet hole 24a connected to the pressure accumulator 5 are concentrically formed in communication, and the communication portion A fuel passage hole 23 has a valve seat 25 at a stepped portion, a piston 21c having a valve portion 21a at one end, a piston 21c having approximately the same diameter as the small diameter hole 23b at the other end, and a connecting rod portion 21b in the middle. The connecting rod portion 21b includes an on-off valve 21 formed smaller than the diameter of the piston 21c, and the on-off valve 21
is inserted into the fuel hole 23, and the spring 26
When the valve portion 21a is seated on the valve seat 25, fuel pressure is applied to the valve portion 21a and the piston 21c via the fuel inlet hole 24a so as to offset each other, and furthermore, the piston of the on-off valve 21 2
1c, and the on-off valve 21 is lifted by the hydraulic pressure applied from the pressure generator 27 against the force of the spring 26 to open the fuel inlet hole 24a and the fuel outlet hole 24b. A valve device for a fuel injection device that communicates with the valve device.