JPS595161Y2 - Injection timing adjustment device for distributed fuel injection pump for diesel engine - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to an injection timing adjustment device for a distributed fuel injection pump for a diesel engine.

Starting performance of a diesel engine is improved by advancing the injection timing by a certain angle, so an injection timing adjustment device that can advance the injection timing at startup (obtaining a starting advance angle) is effective, and various proposals have been made to date. It had been.

However, in the past, an auxiliary piston for obtaining a starting advance angle was placed on the high-pressure oil chamber side of the timer piston, facing the timer piston.

Therefore, the auxiliary spring that presses the auxiliary spring to obtain the starting advance angle must displace the timer piston against the pressing force of the timer spring and the force of the roller holder being pushed by the cam and trying to displace to the lag side. The auxiliary spring had to be strong.

Furthermore, after the engine has started, the auxiliary piston must be positioned outside the timer piston's displacement range so that it will not affect the movement of the timer piston even if the engine speed drops to idle speed. For this reason, the pressure-receiving area on the high-pressure oil chamber side of the auxiliary piston had to be increased, making it large and disadvantageous for installation in the engine.

In this invention, the auxiliary piston is located on the low pressure side of the timer piston, and the timer spring is placed between the timer piston and the auxiliary piston, allowing control even if the auxiliary spring is weak, reducing the pressure receiving area of the auxiliary piston, and making it more compact. It was measured.

Next, an embodiment of the present invention will be described with reference to the drawings.

The main body 1 of the distribution type fuel injection pump includes a timer piston 2.
A cylinder 3 is formed to house the oil, and one end of the cylinder 3 is closed by a plate 4 to form a high pressure oil chamber 5.

The high pressure oil chamber 5 is connected to a passage 6 formed in the timer piston 2.
, communicates with a pump chamber (not shown) in the main body 1 via an orifice 7.

The timer piston 2 is connected to a roller holder (not shown) in the pump chamber by a swingably provided lever 8.

A low pressure chamber 10 is formed at the other end of the timer piston 2 and communicates with the low pressure side through a hole 9. A cylinder 12 for housing an auxiliary piston 11 is formed in the low pressure chamber 10, and the auxiliary piston 11 and the timer A timer spring 13 is disposed between the pistons 2, and a rod 15 having a pin 14 is fixed to the auxiliary piston 11.

The pin 14 engages with a long groove 16 formed in the timer piston 2, and has the function of displacing the timer piston 2 to the starting advance position by the movement of the auxiliary piston 11, and also so as not to impede the movement of the timer piston after starting. has been done.

A wall 17 for determining the amount of displacement of the auxiliary piston 11 and a wall 18 for determining the amount of displacement of the timer piston 2 are further formed in the low pressure chamber 10, and an auxiliary spring 19 is provided between the main body 1 and the auxiliary piston 11. .

A pressure oil chamber 20 is formed on the other end side of the auxiliary piston 11,
The auxiliary piston 11 is pushed toward the pressure oil chamber 20 by an auxiliary spring 19.

The pressure oil chamber 20 includes a check valve 2 having an orifice 21.
2 communicates with the pump room.

The check valve 22 blocks the flow of oil from the pump chamber to the pressure oil chamber 20, and the orifice and check valve may be separate bodies.

Next, the operation of the above configuration will be explained.

When the engine is stopped, the force of the auxiliary spring 19 should be greater than the force with which the roller holder is pushed by the cam, so the auxiliary spring 19 is connected to the auxiliary piston 11 and a timer screw connected to the auxiliary piston 11 via a rod 15 and a pin 14. 2 to the starting advance angle position.

The pressure-receiving area of the auxiliary piston 11 on the pressure oil chamber 20 side is an area that can displace the auxiliary piston 11 to a position in contact with the wall 17 against the auxiliary spring 19 when the engine speed increases to about idling rotation. Therefore, when the engine starts and the rotation starts to rise, the start advance angle is canceled and the timer piston is returned to the advance angle 0 position, but the oil in the pump chamber is introduced into the pressure oil chamber 20 through the orifice 21. Therefore, the increase in pressure in the pressure oil chamber 20 is delayed compared to the increase in the oil pressure in the pump chamber (-the oil pressure in the high pressure oil chamber 5) due to the increase in rotation.

Therefore, at the time of starting, it is possible to provide a starting advance angle until the engine speed rises to about the idling speed.

- When the engine rotates, the auxiliary piston 11 moves against the wall 17.
Since the auxiliary piston is in contact with the timer piston 2, the auxiliary piston does not interfere with the movement of the timer piston 2 thereafter.

When the engine is stopped, the oil pressure in the pump chamber decreases, so the oil in the pressure oil chamber 20 returns to the pump chamber at once by the operation of the check valve 22, and the auxiliary piston 11 returns to the starting advance angle position in preparation for the next starting.

As described above, in the injection timing adjusting device of the present invention, the setting force of the auxiliary spring can be weakened without the auxiliary piston and the auxiliary spring receiving the action force of the timer spring.

Therefore, the pressure-receiving area of the auxiliary screw I/N can be reduced, making it possible to downsize the device.

[Brief explanation of the drawing]

The figure shows an embodiment of the invention. 1: Main body, 2: Timer piston, 11: Auxiliary piston, 13: Timer spring, 14: Pin, 15: Rod, 16: Long groove, 19: Auxiliary spring.

Claims (1)

[Scope of utility model registration request] An auxiliary piston is provided on the low pressure side of the timer piston to receive the setting force of the timer spring, the auxiliary piston and the timer piston are connected by a retaining member, and the auxiliary spring is provided between the fuel injection pump body and the auxiliary piston, and the auxiliary piston is An injection timing adjustment device for a distribution type fuel injection pump for an easel engine, characterized in that a pressure oil chamber communicating with a pump chamber is provided on the side opposite to the spring.