JPS6136775Y2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improvement of a discharge valve with a suction collar for a fuel injection pump.

Problems with fuel injection systems include secondary injection and cavitation erosion. In order to prevent this, as shown in FIG.
1, a cushion portion protrusion 103 and a valve seat metal 10 of the discharge valve are provided at the lower part of the discharge valve body 101.
A discharge valve with a cushion part has been proposed in which a cushion part hole 104 is provided in the second part (Japanese Patent Publication No. 47-29616).
(see publication).

However, the effect of the cushion part of this discharge valve is
During the suction and return period, conversely, during the discharge period, the cushion portion causes the discharge valve to jump up, resulting in major drawbacks such as breakage of the discharge valve spring.

As a countermeasure to this problem, a discharge valve with a check valve inside the discharge valve seat shown in FIG. 1 and a discharge valve with a check valve inside the discharge valve main body shown in FIG. 2 have been proposed.

The discharge valve of FIG. 1 has oil passages 105 and 110 in the valve seat of the original discharge valve with a cushion part,
In between, there is provided a check valve consisting of a ball valve 107, a valve seat 106, a ball valve pressing spring 108, and a stopper 109. Therefore, the ball valve 107 opens from the beginning of discharge, and can receive the pressure of the plunger chamber through the wide width of the suction collar 111 in the same way as a normal discharge valve.

The discharge valve shown in FIG. 2 has a check valve having the same function as that shown in FIG. 1 in the discharge valve body 202. The check valve is located between the oil passages 205 and 208, and the ball valve 206
Valve seat 207, ball valve pressing spring 204 and stopper 2
Consists of 03. In addition, 201 is the valve seat metal, 209
210 is a cushion part protrusion, 210 is a cushion part hole,
211 is a suction collar.

However, the conventional method described above has the following drawbacks.

(b) A discharge valve with a check valve cushion requires another check valve in addition to the discharge valve, making the mechanism complicated and requiring high costs to ensure perfect sealing. Machining precision is required.

(b) If the check valve is not reliable and durable, the check valve's seating and oil tightness will deteriorate, and the effectiveness of the cushion parts 103, 104, 209, and 210 shown in Figures 1 and 2 will be lost. , there is a high risk that the discharge valve with the cushion part will not function as intended.

(c) The discharge valve with a cushion part that has the valve seat shown in Figure 1 requires machining of the valve seat, and the valve seat is not axially symmetrical, making it difficult to deform due to tightening force.

(d) In the discharge valve with a cushion part that has a check valve in the discharge valve body shown in FIG.
7 must be seated to ensure complete oil tightness, and there are problems with the operability and durability of the check valve.

The object of the present invention is to provide a delivery valve with a cushion portion which can eliminate the above-mentioned drawbacks and realize a fuel injection system with high durability and reliability. The characteristic feature of this invention is that the cushion portion protrusion itself is made movable without using a check valve.

An embodiment of the present invention will be described below with reference to the drawings.

FIG. 3 is a sectional view showing a discharge valve with a cushion part according to an embodiment of the present invention.

In the figure, 1 is a valve seat metal, 2 is a discharge valve body, and a cushion portion protrusion 6 coaxial with the discharge valve body 2 is slidably housed in the center thereof.

Reference numeral 8 denotes a cushion hole that communicates between a cavity (described later) formed on the outer periphery of the discharge valve main body 2 and a plunger chamber formed inside the plunger barrel (not shown). A cushion portion protrusion 7 that protrudes and retracts into the cushion portion hole 8 is formed at the lower end of the cushion portion projection tube 6. As shown in FIG. In addition, a return spring 4 is interposed between the upper end side of the cushion part projecting tube 6 and a spring holder 3 screwed onto the discharge valve chamber side of the central part of the discharge valve main body 2, and a return spring 4 is interposed between the spring holder 3 and the spring holder 3. A gap is formed that allows for directional displacement.

Reference numeral 5 denotes an oil passage provided in the discharge valve body 2, which communicates the above-mentioned gap in the center of the discharge valve body 2 with a space formed on the side of the cushion portion protrusion 7 rather than the suction return collar 9 of the discharge valve body. There is.

The operation in the case of the above configuration will be described.

When oil pressure from the plunger acts on the end face of the cushion part projection 7 at the beginning of discharge, the cushion part projection tube 6 moves upward in the discharge valve body 2 against the elasticity of the return spring 4, thereby causing the internal oil chamber to be filled. Hydraulic pressure from oil acts directly below the suction collar 9 through the oil passage 5, and also acts on the central part of the discharge valve body 2, so that the discharge valve moves in the same way as a normal discharge valve without a cushion part protrusion. It will be held during the period. This prevents the valve from jumping up, which is a drawback of discharge valves with cushions. Also, before the suction-back period begins, the cushion part protrusion 7 returns to the home position by the spring 4,
When the discharge valve enters the cushion hole 8, the suction and return speed of the discharge valve is controlled, and the discharge valve with the cushion functions normally.

That is, before the plunger is discharged, the oil passage transmits the fuel pump discharge pressure p acting on the cushion part protrusion to the suction collar, and the suction collar transmits the fuel pump discharge pressure p acting on the cushion part protrusion to the oil passage. It receives pressure through and starts the lift. The cushion part projection cylinder receives the fuel pump discharge pressure p, and according to the lift of the suction-return valve, the cushion part projection cylinder itself also pushes the spring. Immediately after the cushion section is cleared, the oil passage transmits the fuel pump discharge pressure to the suction collar to prevent unevenness between the two, the suction collar continues to lift in response to the fuel pump discharge pressure, and the protrusion tube of the cushion section transfers the suction back pressure. Push the spring according to the lift of the collar and move to the maximum movable position. Before the suction collar clears, the oil passage has no special action, the suction collar continues to lift under the pump discharge pressure, and the cushion part protrusion begins to return to its seat due to the restoring force of the spring. After the suction collar is cleared, the oil passage has no special action, the suction collar transmits the fuel oil pressure to the fuel high pressure pipe, and the cushion portion protrusion completes its re-seating.

As described above, the present invention has the following effects.

Since a check valve is not used in the discharge valve with a cushion part, the suction-back speed of the discharge valve can be reliably controlled during the suction-back period when the discharge valve with a cushion part performs its original function. Problems such as secondary injection and cavitation erosion can be reliably prevented.

Further, by adjusting the length of the cushion portion protrusion and the clearance between the cushion portion hole and the cushion portion protrusion, the suction and return speed of the discharge valve can be controlled.

[Brief explanation of the drawing]

1 and 2 are sectional views showing the structure of a conventional discharge valve with a cushion part, respectively, and FIG. 3 is a sectional view showing the structure of a discharge valve with a cushion part according to an embodiment of the present invention. DESCRIPTION OF SYMBOLS 1...Valve seat hardware, 2...Discharge valve body, 3...Spring holder, 4...Spring, 5...Oil passage, 6...Cushion part protrusion tube, 7...Cushion part protrusion, 8...
...Cushion hole, 9...Suction back collar.

Claims (1)

[Scope of utility model registration request] In a discharge valve for a fuel injection pump having a suction collar, a cushion part hole that communicates a plunger chamber with a cavity formed on the outer circumference of a discharge valve body that is fitted to a valve seat metal so as to be slidable in a reciprocating manner; A column-shaped cushion portion protrusion is formed at the distal end of the valve body so as to be slidably reciprocally fitted into the valve body, and is capable of moving in and out of the cushion portion hole, and is always inserted into the cushion portion hole when the discharge valve is seated. a projection tube of the cushion portion, a return spring interposed between the projection tube of the cushion portion and the discharge valve body and biasing the projection of the cushion portion in a direction to enter the hole of the cushion portion; An oil passageway is provided that communicates the internal oil chamber defined between the upper end face and the inner periphery of the hole that is fitted into the cushion portion protrusion tube of the discharge valve main body, and the cavity. Fuel injection pump discharge valve.