JPH0455254Y2 - - Google Patents

Description

[Detailed description of the invention] [Industrial field of application] This invention relates to a pressure equalizing valve device for a fuel injection pump, and in particular to a pressure equalizing valve for a fuel injection pump which is improved by adopting a poppet valve for controlling the residual pressure in the piping between the fuel injection pump and the fuel nozzle after the end of fuel injection.

[Prior Art] Conventionally, there has been a fuel injection pump incorporating a pressure control device called an equal pressure valve in order to control the residual pressure after the end of fuel injection in a pipe between the fuel injection pump and a fuel nozzle.

For example, many equal pressure valves such as the fuel injection pump shown in JP-A No. 60-247049 use a ball valve as the valve body incorporated in the equal pressure valve. Alternatively, since it is difficult to guide the set spring that applies the valve opening pressure to the valve body, there is a problem of wear due to buckling of the set spring, and the structure becomes complicated if attempts are made to prevent buckling.

Therefore, in order to solve the problem of wear due to buckling of the set spring, some devices have been devised in which a poppet valve is used as the valve body of the equal pressure valve device. For example, there is an equal pressure valve device disclosed in Japanese Utility Model Application No. 58-102770. However, in an equal pressure valve device, the orifice effect at this time is an important performance determining factor, as well as the valve opening pressure during fuel suction. In other words, if the equal pressure valve is opened immediately due to fuel reflection pressure from the fuel injection pipe, the fuel pressure in the delivery valve or fuel injection pipe will drop too much, resulting in poor fuel injection response during the next fuel injection. Because of this problem, it is desirable to throttle the reflected pressure once when sucking back the fuel, and then return the excess fuel to the pump chamber. However, the above-mentioned Utility Model 58
In the equal pressure valve device disclosed in No. 102770 and the like, an orifice cannot be provided due to its structural limitations, so it is impossible to achieve the above-mentioned orifice effect.

[Problems to be solved by the invention] The present invention was developed in view of the above-mentioned problems, and aims to solve the problem of wear due to buckling of the equal-pressure valve set spring in an equal-pressure valve device and to simplify the entire device. It is an object of the present invention to provide an equal pressure valve device for a fuel injection pump which has excellent residual pressure adjustment performance and fuel injection responsiveness by making it possible to achieve an orifice effect during fuel return.

[Means for Solving the Problems] That is, the present invention forms a fuel return passage in a delivery valve that opens and closes a fuel outlet of a fuel injection pump, and stores only the return fuel from the fuel outlet side in this fuel return passage. A poppet valve that allows passage is provided as a valve body of an equal pressure valve, and an orifice is provided in either the poppet valve or the delivery valve so that the fuel return passage and the fuel outlet can communicate with each other. This is an equal pressure valve device for a fuel injection pump.

[Function] In the equal pressure valve device of the present invention, a poppet valve is adopted as the valve body of the equal pressure valve, so the mechanism for guiding it in the length direction can be simplified, and the poppet valve can be slidably incorporated. Since an orifice is provided on either the delivery valve or the poppet valve, the fuel pressure reflected from the fuel outlet can be throttled once at this orifice and then returned to the fuel return passage, thereby achieving a sufficient orifice effect. It is possible to achieve this.

[Example] Next, an example 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 pumped from the pump chamber 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 radially protruding a plurality of vanes 13 (see FIG. 2). This fuel discharge passage 14 communicates with the mechanical pump chamber 7 . Furthermore, by providing a delivery valve set spring 16 between the step part of the seat part 11 of the delivery valve 9 and the spring stopper 15, the seat part 11 of the delivery valve 9 is set to the seat surface of the delivery valve seat 8. It is always pressed to 17.

An equal pressure valve storage chamber 19 is formed in the delivery valve 9 to accommodate the equal pressure valve 18 coaxially with the delivery valve 9. The equal pressure valve storage chamber 19 accommodates a set spring storage portion 19A that stores an equal pressure valve set spring 20, and a long poppet valve 21 as a valve body of the equal pressure valve 18 so as to be slidable up and down in FIG. It consists of a poppet valve housing section 19B.

The poppet valve 21 has a head portion 21A.
and a lower guide portion 21B and an upper guide portion 21C that maintain oil tightness between the delivery valve 9 and the delivery valve 9;
It has a chip portion 21D. This chip part 21D
The head portion 21A is moved toward the delivery valve 9 by the biasing force of the equal pressure valve set spring 20 interposed between the set spring seat 22 fixed to the set spring seat 22 and the inner wall surface of the set spring storage portion 19A.
The robot is seated on the seat portion 23 of the vehicle under a predetermined pressure.

Further, an orifice 24 is formed in the cylindrical portion 12 of the delivery valve 9, and a fuel return passage 25 is formed between the poppet valve guide relief portion 21E formed in the poppet valve 21 and the inner circumferential wall of the poppet valve storage portion 19B. It is possible to communicate with the fuel outlet 3. As shown in FIG. 2, a flat cut 26 is formed in one of the lower guide parts 21B to communicate the upper and lower fuel return passages 25 of this lower guide part 21B.

In the fuel injection pump 1 having the above structure, when fuel is force-fed from the pump chamber 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, and the equal pressure valve 18 moves integrally with the delivery valve 9. Therefore, the space between the delivery valve 9 and the seat surface 17 is opened, and fuel is injected into the cylinder (not shown) from the injection nozzle 5 through the fuel outlet 3 and the injection pipe 4.

When this fuel injection is completed and the residual pressure due to the fuel in the fuel injection pipe 4 and delivery valve holder 2 is applied to the equal pressure valve 18, the fuel having this reflected pressure is first throttled at the orifice 24, and then the fuel is returned. The pressure inside the passage 25 is increased, and the equal pressure valve 1 is set against the biasing force of the equal pressure valve set spring 20.
By moving the poppet valve 21 of No. 8 downward in the figure, its head portion 21A is separated from the seat portion 23 of the delivery valve 9, and the equal pressure valve 18 is opened. Thus, the residual pressure is regulated and the poppet valve 21 is closed.

Furthermore, even if the poppet valve 21 slides in the vertical direction in FIG. 1 during such a residual pressure adjustment operation, the poppet valve 21 is supported and guided by the upper guide part 21 and the lower guide part 21B, so that it is prevented from falling down. be able to.

In this way, the reflected pressure from the injection pipe 4 is once throttled at the orifice 24 and then regulated, so that a sufficient orifice effect can be obtained.

By appropriately designing the outer diameter of the poppet valve guide relief portion 21E or the dimensions of the flat cut 26, it is also possible to achieve the same effect as the orifice 24 in these portions.

Furthermore, in the above embodiment, the orifice 2
Although an example in which the orifice 4 is formed in the delivery valve 9 has been described, in the present invention, it is also possible to form the orifice in the poppet valve itself.

That is, as shown in FIG. 3, a long communication hole 31 may be formed in the axial center of the poppet valve 30, and an orifice 32 may be formed so as to communicate this communication hole 31 with the fuel return passage 25. It is possible.

Further, the present invention can be applied to either a distribution type or a row type fuel injection pump.

[Effects of the invention] As explained above, according to the invention, a poppet valve is adopted as a valve body of an equal pressure valve device provided in a delivery valve of a fuel injection pump, and an orifice is provided in either the poppet valve or the delivery valve. Furthermore, since the poppet valve is supported and guided by the upper guide part and the lower guide part, the stable equal-pressure valve function when regulating the residual pressure inside the fuel injection pump and the orifice effect improve the pressure regulation performance, and further improve the operation of the poppet valve. The effect of stability can be obtained.

[Brief explanation of the drawing]

Fig. 1 is a vertical cross-sectional view of essential parts of an equal pressure valve device for a fuel injection pump according to an embodiment of the present invention, Fig. 2 is a cross-sectional view taken along the line - - in Fig. 1, and Fig. 3 shows another example of the orifice formation portion. FIG. 1...Fuel injection pump, 2...Delivery valve holder, 3...Fuel outlet, 4...Injection pipe, 5...
Injection nozzle, 6...Fuel injection pump body, 7...
Pump chamber, 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, 13... Vane part, 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, 19A... Set spring storage section, 19B... Poppet valve storage section,
20: Equal pressure valve set spring, 21: Poppet valve, 21A: Head portion of poppet valve 21, 21B: Lower guide portion of poppet valve 21, 21C: Upper guide portion of poppet valve 21, 21D: Tip portion of poppet valve 21 ,
21E...Poppet valve guide relief part, 22...
... Set spring seat, 23 ... Seat part of poppet valve 21, 24 ... Orifice, 25
...Fuel return passage, 26...Flat cut,
30...Poppet valve, 31...Communication hole, 32
...Orifice chair.

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 a fuel return passage is formed in the delivery valve, and the fuel return passage is provided in the delivery valve. A poppet valve that allows passage of only return fuel from the outlet side is slidably accommodated, the poppet valve is supported and guided by an upper guide portion and a lower guide portion, and the fuel return passage and the fuel outlet are communicated. An equal pressure valve device for a fuel injection pump, characterized in that an orifice is provided in either the poppet valve or the delivery valve.