JPS6235863Y2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a fuel injection pump equipped with a pneumatic governor.

As a diesel engine fuel injection pump,
2. Description of the Related Art A fuel injection pump equipped with a pneumatic governor that controls the pump injection amount in accordance with negative pressure generated near a butterfly valve provided in an intake passage is known.

To explain this based on FIG. 1, a butterfly valve 2 which is interlocked with an accelerator pedal is provided in an intake passage 1 of an engine.

The negative pressure outlet passage 3 opened near the butterfly valve 2 allows the negative pressure chamber 5 of the fuel injection pump 4 to
The negative pressure generated according to the opening degree of the butterfly valve 2 is transmitted to the butterfly valve 2.

The negative pressure chamber 5 is separated from the atmospheric chamber 9 by a diaphragm 6, and one end of a control rack 7 for increasing or decreasing the fuel injection amount is connected to the diaphragm 6, and the control rack 7 is connected to the diaphragm 6 to adjust the control rack 7 based on the balance between the diaphragm return spring 8 and the negative pressure. The diaphragm 6 is displaced to perform feedback control of the fuel injection amount.

Therefore, the fuel injection amount is corrected so that the engine speed is always constant for the same accelerator opening.

By the way, in this pneumatic governor, when the accelerator pedal is released from a normal driving state to a deceleration state, the diaphragm 6 is largely displaced due to the strong negative pressure generated due to the sudden closing of the butterfly valve 2. However, the amount of fuel injected decreases rapidly.

For this reason, a sudden engine brake is applied especially at the beginning of deceleration, resulting in very poor drivability.Also, when the rotation speed drops momentarily due to this engine brake, the negative pressure near the butterfly valve 2 weakens, and the pneumatic governor The so-called hunting phenomenon occurs in which the fuel increases again.

In order to avoid such a phenomenon, an orifice is provided in the middle of the negative pressure outlet passage 3 communicating with the negative pressure chamber 5 to weaken the rate of change of negative pressure during deceleration, etc., and smooth transient characteristics. However, in this case, there was a problem that the amount of injected fuel could not be increased quickly during acceleration, resulting in poor acceleration response.

The present invention is intended to solve these problems, and provides a fuel injection pump with a pneumatic governor that exhibits quick response during acceleration and performs gentle deceleration when the accelerator is suddenly closed.

That is, the present invention introduces the negative pressure generated according to the opening degree of the butterfly valve provided in the intake passage into the negative pressure chamber defined by the diaphragm through the negative pressure extraction passage, and In a fuel injection pump that performs feedback control of the fuel injection amount,
A check valve formed by pressing a valve plate with an orifice in the valve closing direction via a spring is provided at the inlet of the negative pressure chamber of the fuel injection pump as a negative pressure delay means, and strong negative pressure during deceleration is transmitted through the orifice. The negative pressure is gradually transmitted to the negative pressure chamber, while the rapid decrease in negative pressure during acceleration is quickly transmitted to the check valve.

Hereinafter, embodiments of the present invention will be described based on the drawings.

As shown in FIG. 2, a negative pressure delay means 13 consisting of an orifice 11 and a check valve 12 is provided at the inlet 10 of the negative pressure chamber 5 of the fuel injection pump 4.

A nipple 16 is screwed into a mounting screw hole 15 of the pump housing 14.
A stepped hole 17 passes through the inside of the plate 6 .

The stepped hole 17 includes a valve plate 19 that comes into contact with and separates from the stepped seat portion 18, a spring 20 that presses the valve plate 19 in the valve closing direction, and a retaining ring 21 that supports one end of the spring 20. A spring catch 22 is provided.

An orifice 11 is formed in the center of the valve plate 19, and when the change in negative pressure from the negative pressure outlet passage 3 is small, negative pressure is transmitted to the negative pressure chamber 5 via this orifice 11.

Next, the effect will be explained.

During steady operation with little change in the opening of the butterfly valve 2 in the intake passage 1, the spring 20
The valve is closed and the negative pressure chamber 5 is opened via the orifice 11.
However, since the negative pressure value changes slowly, there is almost no effect of response delay even after passing through the orifice 11, and the fuel injection amount (engine speed) is controlled in response to the accelerator opening. will be held.

Next, when the engine is decelerating, the negative pressure transmitted to the negative pressure outlet passage 3 increases rapidly as the butterfly valve 2 closes rapidly.

However, since the check valve 12 is brought into close contact with the seat portion 18 due to this strong negative pressure and the action of the spring 20, the negative pressure is transmitted to the negative pressure chamber 5 while being restricted by the orifice 11.

Therefore, the negative pressure change in the negative pressure chamber 5 is delayed in time compared to the negative pressure change in the vicinity of the butterfly valve 2, and as a result, the fuel injection amount sharply decreases at the beginning of deceleration, resulting in strong engine braking. It is possible to prevent the phenomenon of excessive application.

Note that the negative pressure transmitted through the orifice 11 becomes the same as the negative pressure value of the negative pressure outlet passage 3 after a response delay time proportional to the negative pressure change value.
If the deceleration state continues thereafter, the amount of fuel injected will be commensurate with the deceleration state at that time, and appropriate engine braking effectiveness can be maintained.

On the other hand, when the engine accelerates, the negative pressure generated near the butterfly valve 2 rapidly decreases as the accelerator pedal is suddenly opened. Therefore, the residual negative pressure on the negative pressure chamber 5 side becomes stronger than that on the negative pressure extraction passage 3 side.
The check valve 12 opens against the elastic force of the spring 20, and the negative pressure in the intake passage 1 is immediately transmitted to the negative pressure chamber 5.

Therefore, during acceleration, negative pressure is transmitted with good response, and the amount of fuel injection is instantly increased, resulting in good acceleration characteristics.

In this embodiment, the negative pressure delay means 13 is provided at the entrance of the negative pressure chamber 5, but it may also be provided in the middle of the negative pressure outlet passage 3, or the check valve 12 and orifice are provided separately. 11 may be arranged in parallel.

As described above, according to the present invention, negative pressure is transmitted to the negative pressure chamber via the negative pressure delay means consisting of a check valve and an orifice, so that the negative pressure is transmitted with excellent responsiveness during acceleration. During deceleration, negative pressure transmission is delayed to prevent sudden engine braking and hunting, resulting in stable deceleration characteristics.

In addition, in this invention, as a negative pressure delay means, an orifice formed in the valve plate of the check valve is assembled to the negative pressure chamber inlet of the fuel injection pump, so that it has excellent reliability and durability as a negative pressure delay means. This has the advantage that in addition to ensuring good performance, piping between the fuel injection pump and the intake passage becomes easier.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of a conventional device, and FIG. 2 is a sectional view of a main part of the present invention. 1...Intake passage, 2...Butterfly valve, 3
... Negative pressure outlet passage, 5 ... Negative pressure chamber, 6 ... Diaphragm, 7 ... Control rack, 11 ... Orifice, 12 ... Check valve, 13 ... Negative pressure delay means.

Claims (1)

[Scope of utility model registration request] Negative pressure generated according to the opening degree of the butterfly valve installed in the intake passage is introduced into the negative pressure chamber defined by the diaphragm through the negative pressure take-off passage, and the amount of fuel injection is feedback based on this negative pressure. In the fuel injection pump, a check valve formed by pressing a valve plate having an orifice in the valve closing direction via a spring is provided at the inlet of the negative pressure chamber of the fuel injection pump as negative pressure delay means. A fuel injection pump with a pneumatic governor.