JPH0426692Y2 - - Google Patents

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to an equal pressure valve device for a fuel injection pump, and is particularly concerned with the residual pressure after the completion of fuel injection in the piping between the fuel injection pump and the injection nozzle. The present invention relates to an equal pressure valve device for a fuel injection pump that has an improved equal pressure valve for controlling the same pressure.

[Conventional technology]

2. Description of the Related Art Conventionally, there are fuel injection pumps that incorporate a pressure control device called an equal pressure valve in order to control the residual pressure after completion of fuel injection in a pipe between a fuel injection pump and an injection nozzle.

For example, in many equal pressure valves such as the fuel injection pump shown in Japanese Patent Application Laid-Open No. 60-247049, the equal pressure valve seat on which the ball valve as the valve element incorporated in the equal pressure valve seats is fixed, so the ball valve is When the valve is closed, the impact on the equal pressure valve seat is large, and the pressure vibrations in the injection pipe and delivery valve due to the residual pressure cause chattering between the ball valve and the equal pressure valve seat, reducing the durability of the ball valve. There are drawbacks to doing so. In order to solve these drawbacks, it is necessary to put a restriction in the upper part of the ball valve to prevent the ball valve from closing and opening suddenly, and to ensure durability. There was a problem that the pressure drop inside the fuel injection pipe became slow and the fuel injection cut-off worsened.

[The problem that the idea aims to solve]

The present invention was developed in view of the above-mentioned problems, and is designed to reduce the impact of closing the valve body in an equal-pressure valve device, as well as to buffer the subsequent pressure vibrations. It is an object of the present invention to provide an equal pressure valve device for a fuel injection pump in which the durability of the seat and the valve body portion is improved without impairing the injection performance.

[Means to solve the problem]

That is, the present invention is an equal-pressure valve device installed in a delivery valve that opens and closes the fuel outlet of a fuel injection pump, in which the equal-pressure valve seat on which the equal-pressure valve seats is movable in the fuel discharge direction and the fuel suction direction. This is an equal pressure valve device for a fuel injection pump, characterized in that a buffer spring is provided on the pressure valve seat.

[Operation] In the equal pressure valve device of the present invention, the equal pressure valve seat is movable and a buffer spring is applied to it, so that the equal pressure valve opens due to the reflected pressure from the fuel injection pipe upon completion of fuel injection. The movable isobaric valve seat and buffer spring absorb the impact when the valve closes upon completion of fuel suction, and the buffer spring also absorbs pressure vibrations that occur within the fuel injection pipe and delivery valve. It can be quickly damped to achieve a rapid pressure drop.

〔Example〕

Next, an embodiment of the present invention is shown in FIGS. 1 and 2.
This will be explained based on the diagram.

FIG. 1 is a longitudinal sectional view showing a portion of a delivery valve holder 2 of a fuel injection pump 1. This delivery valve holder 2 has a fuel outlet 3 at its upper end and is connected to an injection nozzle 5 via an injection pipe 4. It's connected.

The delivery valve holder 2 is attached to the fuel injection pump main body 6, and discharges and pressure-feeds the fuel fed from the distribution passage 7 to the injection nozzle 5 from the fuel outlet 3.

A delivery valve seat 8 is fixed to the lower part of the delivery valve holder 2, and a delivery valve 9 is housed within the delivery valve seat 8 so as to be able to reciprocate up and down. This delivery valve 9 has a rod portion 10, a seat portion 11, and a cylindrical portion 12. A fuel discharge passage 14 is formed between the rod portion 10 and the delivery valve seat 8 by providing a plurality of blade portions 13 projecting radially. This fuel discharge passage 14 communicates with the distribution passage 7 described above. By providing a delivery valve set spring 16 between the spring seat stepped portion 12A of the cylindrical portion 12 of the delivery valve 9 and the spring stopper 15, the seat portion 11 of the delivery valve 9 is set to the seat of the delivery valve seat 8. It is constantly pressed against the surface 17.

The cylindrical portion 12 of the delivery valve 9 extends upwardly in the figure from the seat portion 11, and is provided within the cylindrical portion 12 for housing the equal pressure valve 18 coaxially with the delivery valve 9. An equal pressure valve storage chamber 19 is formed, and a fuel return passage 20 that communicates the equal pressure valve storage chamber 19 with the distribution passage 7 is formed in the rod portion 10.

The equal pressure valve 18 is formed as a ball valve type, and includes a ball valve 21 and a ball valve 2.
A movable equal pressure valve seat 22 on which the ball valve 1 is seated, a spring seat 23 supporting the ball valve 21 from below, and an equal pressure valve set spring 24 interposed between the spring seat 23 and the inner wall of the delivery valve 9; It has a buffer spring 26 interposed between the movable equal pressure valve seat 22 and the upper lid 25.

The movable equal pressure valve seat 22 and the upper lid 25 have an orifice 27 and an orifice 28 in the upper center thereof, which communicate with the fuel outlet 3. The upper lid 25 fixes the upper part of the delivery valve 9 by crimping it.

A stopper step 12B for suction and return is formed on the inner peripheral surface of the cylindrical portion 12 of the delivery valve 9, and a step 22A for suction and return is also formed on the outer peripheral surface of the movable equal pressure valve seat 22. By appropriately selecting the spring forces of the set spring 24 and the buffer spring 26, in a stationary state where fuel injection is not performed, only a suction stroke S is provided between the stopper step 12B and the suction and return step 22A. There are intervals of .

Therefore, the movable equal pressure valve seat 22, the ball valve 21, and the spring seat 23 can be slid in both the vertical direction in the fuel discharge direction and the fuel suction direction by the pressure on the injection pipe 4 side. The stepped portion 12B is used as a stopper to restrict further descent and maintain the oil tightness of the injection pipe 4 side pressure. Furthermore, when the suction/return step 22A of the movable isobaric valve seat 22 is not in contact with the stopper step 12B, the ball valve 21 moves up and down integrally with the movable isobaric valve seat 22, but when it comes into contact, the injection The equal pressure valve set spring 24 is compressed by the pressure on the pipe 4 side, and the equal pressure valve 18 is opened.

In the fuel injection pump 1 having the above structure, when fuel is force-fed from the distribution passage 7 to the delivery valve 9 portion by the operation of the plunger (not shown), the delivery valve sets against the biasing force of the delivery valve set spring 16. 9 moves upward, the upper and lower pressures of the movable equal pressure valve 22 and the ball valve 21 become the same, and the equal pressure valve 18 is delivered to the position where the equal pressure valve set spring 24 and the buffer spring 26 are balanced or to the position where it contacts the upper cover 25. It moves integrally with valve 9. Therefore, the space between the delivery valve 9 and the seat surface 17 is opened,
Fuel is injected into a cylinder (not shown) from an injection nozzle 5 through a fuel outlet 3 and an injection pipe 4.

In the later stage of fuel injection when this fuel injection is completed and the residual pressure due to the fuel in the fuel injection pipe 4 and the delivery valve holder 2 is applied to the equal pressure valve 18,
The movable equal pressure valve seat 22 of the equal pressure valve 18 moves down by the suction stroke S against the biasing force of the equal pressure valve set spring 24, and the upper part of the equal pressure valve storage chamber 19, that is, between the equal pressure valve 22 and the upper cover 25. By increasing the volume of the fuel, a rapid drop in pressure is ensured, and a suction-back effect that improves fuel injection cut-off is achieved. Further, at the stage when the suction/return step 22A comes into contact with the stopper step 12B, the space between the ball valve 21 and the movable equal pressure valve seat 22 is opened, and the equal pressure valve 18 is opened.
is opened, a predetermined amount of fuel is sucked back into the distribution passage 7, and the ball valve 21 starts regulating the pressure on the injection pipe 4 side. When the fuel suction is completed,
The space between the ball valve 21 and the movable equal pressure valve seat 22 is closed again by the biasing force of the equal pressure valve set spring 24, so that the equal pressure valve 18 is closed. Even if pressure fluctuations are applied to the delivery valve 21 in the fuel discharge direction and suction direction, the movable isobaric valve seat 22 can move by a slight stroke in both directions, and is provided with a buffering function by the buffer spring 26. The volume of the equal-pressure valve storage chamber 19 is changed to perform the pressure regulating action, thereby speeding up the convergence of the pressure vibrations, reducing the number of openings and closings of the ball valve 21, and achieving a damper effect that quickly attenuates pressure fluctuations.

FIG. 2 is a graph showing the above-mentioned pressure fluctuation state, and as is clear from this graph, the movable equal pressure valve seat 22 and the ball valve 2
The pressure inside the injection pipe 4 rapidly attenuates as the injection pipes 1 move toward and away from each other.

In the above embodiment, an example was described in which the blade portion 13 was formed in the rod portion 10 of the delivery valve 9 in order to form the fuel return passage 20 between the rod portion 10 and the delivery valve seat 8. , the rod portion 10 may simply be formed with a flat cut.

Further, the present invention can be applied to either a distribution type or a row type fuel injection pump, and although an example in which a ball valve 21 is used to regulate the pressure on the injection pipe 4 side has been described, a poppet type valve is also applicable. It is also possible to adopt

[Effect of idea]

As explained above, according to the present invention, the equal pressure valve seat of the equal pressure valve device provided in the delivery valve of the fuel injection pump is movable and a buffer spring is provided, so that the damper is used when regulating the residual pressure in the fuel injection pipe. As a result, it is possible to obtain the effect of improving durability.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal sectional view of an equal pressure valve device for a fuel injection pump according to an embodiment of the present invention, and FIG. 2 is a graph showing pressure fluctuations and stroke fluctuations in the same embodiment. 1...Fuel injection pump, 2...Delivery valve holder, 3...Fuel outlet, 4...Injection pipe, 5...
Injection nozzle, 6...Fuel injection pump body, 7...
Distribution passage, 8...Delivery valve seat, 9...
Delivery valve, 10... Rod portion of the delivery valve 9, 11... Seat portion of the delivery valve 9,
12... Cylindrical part of delivery valve 9, 12A...
Spring seat stepped portion, 12B... Suction/return stopper stepped portion, 13... Vane portion, 14... Fuel discharge passage, 15... Spring stopper, 16...
...Delivery valve set spring, 17... Seat surface, 18... Equal pressure valve, 19... Equal pressure valve storage chamber, 20... Fuel return passage, 21... Ball valve, 22... Movable equal pressure valve seat, 22A... ...Suck-back step, 23...Spring seat, 24...
... Equal pressure valve set spring, 25 ... Top lid, 26
... Buffer spring, 27, 28 ... Orifice, S ... Suction return stroke.

Claims (1)

[Claims for Utility Model Registration] An equal pressure valve device provided in a delivery valve that opens and closes a fuel outlet of a fuel injection pump, wherein an equal pressure valve seat on which a valve body in the equal pressure valve device seats is controlled in the direction of fuel discharge and suction back. 1. An equal-pressure valve device for a fuel injection pump, characterized in that the equal-pressure valve device is movable in a direction, and a buffer spring is provided on the equal-pressure valve seat.