JPS5979067A - Fuel injection control device to be employed for unit injector - Google Patents

Abstract

PURPOSE:To improve combustion efficiency by a method wherein the injection pressure of fuel in the unit injector is increased upon the low speed operation of a diesel engine. CONSTITUTION:A fuel injection device 10 is consisting of an auxiliary tappet 11, transmitting the movement of the cam 15 of a cam shaft 14 arranged in the diesel engine to a push rod 24 so as to drive the cam follower of the unit injector, a control slider 12, arranged between the push rod 24 and the tappet 11 and connecting the lower end of the push rod 24 rotatably, and an actuator. When an operating rod 22 is pushed out upon the low speed operation, an eccentric cam 19 is rotated counterclockwisely and pushes the control slider 12 to the left side. The contact point with a roller 16 is moved to the side of the eccentric cam 19 at the lower surface of the slider 12 and increases the stroke of the push rod 24, therefore, the injection pressure of the unit injector may be increased.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a fuel injection control device used in a unit injector of a diesel engine.

Generally, a unit injector in a diesel engine is driven by a cam shaft of the diesel engine, and is configured to compress fuel to high pressure and inject it.

The injection pressure of fuel at the unit injector is typically determined by the rotational speed of the cam shaft that reciprocates the unit injector's follower and the shape of the cams on the cam shaft.

However, when the diesel engine is operated at low speed, the fuel injection pressure at the unit injector is relatively low, and the combustion efficiency tends to decrease; Since the fuel injection pressure at the unit injector rises to an extremely high pressure, there is a risk that the unit injector's limit pressure will be exceeded and the unit injector will be damaged.

The purpose of this invention is to increase the fuel injection pressure in the unit injector during low speed operation of a diesel engine,
Improves combustion efficiency, maintains fuel injection pressure at high pressure without exceeding the limit pressure of the unit injector during high-speed operation of the diesel engine, and prevents damage to the unit injector. Moreover, it is an object of the present invention to provide a fuel injection control device for use in a unit injector that controls the injection pressure of such fuel by extremely simple means.

In order to solve these problems, the fuel injection control device used in the unit injector of the present invention controls the movement of the cam of the cam shaft disposed in the diesel engine so as to drive the cam follower of the unit injector. a tappet for transmitting information to the rod; a control slider disposed between the bushing rod and the tappet and rotatably connecting the lower end of the bushing rod; and rotatably supporting the control slider; It also includes an actuator for reciprocating movement.

Preferred specific examples of the fuel injection control device used in the unit injector according to the present invention will be described below with reference to the drawings.

1 to 3 schematically show a specific example 10 of a fuel injection control device used in the unit injector of the present invention.

The fuel injection control device 1o includes a tappet 11 that transmits the movement of a cam 14 of a cam shaft 13 arranged in a diesel engine to a bushing rod 24 so as to drive a cam follower of a unit injector, and a bushing rod 24 of the bushing rod 24. It is arranged between the rod 24 and its tab (IJ),
It also includes a control slider 12 to which the lower end of the bushing rod 24 is rotatably connected, and an actuator that rotatably supports the control slider 12 and causes it to reciprocate.

Rinit 11 is the camshaft 13 of a diesel engine.
At a position above the cam 14 at
It is fitted into a jet bore 28 formed in the head 27 so as to be able to reciprocate vertically, and rollers 15 and 16 are rotatably disposed at the lower and upper ends, respectively.

Of course, the bore 215.16 is the tappet bore 2.
8, that is, protrudes downward and upward, respectively.

The roller 15 is connected to the cam surface 1 of the cam shaft 13.
4 and the cam shaft 13 is rotated, thereby causing the tappet 11 to reciprocate in the vertical direction.

The control slider 12 is arranged horizontally so that the lower surface of one end is placed on the roller 16 of the evening wave jet 11, and an eccentric cam 19 is rotatably arranged at the other end.

That is, the control slider 12 integrally forms a connecting portion 17 with a circular bore 18 at the other end, and an eccentric cam 19 is rotatably fitted into the bore 18.

Of course, the eccentric cam 19 is integrally provided with a shirt 20 which is biased to one side.

The control slider 12 also includes a ball seat 23 on the upper surface of one end, and a bushing rod 24.
The ball portion 25 at the lower end of the ball is accommodated in the ball seat 23.

Therefore, the control slider 12 is arranged laterally with the lower surface of one end resting on the roller 16 of the tappet 11, and the shaft 20 of the eccentric cam 19 at the other end is rotatably mounted on the cylinder head 27. Further, a goal portion 25 at the lower end of the bushing rod 24 is housed in a ball seat 23 formed on the upper surface of one end side.

Of course, the upper end of the -7° thrust rod 24 has a rocker rotatably disposed in its cylinder head 27 for pushing in the follower of the unit injector.
An arm (not shown) is connected to the end.

The actuator (not shown) is a hydraulic/cylinder so as to reciprocate the control slider 12 with rotational movement, in other words, to move the eccentric cam 19 depending on the operating conditions of the diesel engine. It is configured to rotate the shaft 20.

That is, the actuator
A cylinder (not shown) disposed near the eccentric cam 19 of the slide finish 12 on the cylinder head side thereof, and a piston (not shown) fitted into the cylinder bore of the cylinder so as to be able to reciprocate and slide; It consists of an operating rod 22 whose one end can be taken in and out of the cylinder and whose other end is connected to the piston.

The end of the operating rod 22 of the actuator is connected to the link 21
The eccentric cam 19 is connected to the shaft 20 of the eccentric cam 19 via the shaft 20 of the eccentric cam 19.

Of course, one end of the link 21 is fixed to the shaft 20 of the eccentric cam 19, and the other end is rotatably connected to the end of the operating rod 22 via a pin 26.

Therefore, if the actuator is driven, the eccentric cam 19 is connected to the shaft 2 via the link 21.
The rotation of the eccentric cam 19 causes the control slider 12 to reciprocate with rotational movement.

The actuator is connected to an oil pump (not shown) driven by the diesel engine via hydraulic piping equipped with a solenoid valve (not shown), and the solenoid valve is controlled by a controller (not shown). has been done.

The controller is a diesel engine rotation speed sensor (
The solenoid valve is controlled by nine preset fuel injection turns in response to a signal from (not shown).
Mainly input and output circuits, memory circuits, arithmetic circuits,
and a control circuit.

Of course, the actuator is Sir? - A motor may be used, and when a servo motor is used, it is controlled by a controller in substantially the same manner as described above.

Next, the operation of the fuel injection control device 10 described above will be described. When a diesel engine is operating, the cam shaft 13 rotates, and the tappet 11 reciprocates in the vertical direction in accordance with the rotation of the cam shaft 13. A control slider 12 rotates the eccentric cam 19.

That is, the movement of the tappet 11 is guided to the unit injector via the bushing rod 24 and the rocker arm, and the unit injector is driven to inject fuel.

In this case, the injection pressure of the fuel is determined by the position of the control slider 12.

For example, when the diesel engine operates at low speed, the controller controls the solenoid valve, drives the actuator, and pushes out the operating rod 22.

When the operating rod 22 is pushed out, the eccentric cam 19 rotates counterclockwise around the shaft 20, as shown in FIG. is pushed to the left.

That is, on the lower surface of the control slider 12, the contact point of the tappet 11 with the roller 16 moves toward the eccentric cam 19, and the control slider 1
6 becomes shorter.

Therefore, the stroke of the bushing rod 24 connected to the upper surface of one end of the control slider 12 becomes large, and the speed of the bushing rod 24 becomes fast, so that the fuel in the unit injector during low-speed operation is increased. injection pressure is increased and combustion efficiency is improved.

If the diesel engine is still operating at high speed, the controller controls the solenoid valve and drives the actuator to retract the operating rod 22.

When the operating rod 22 is retracted, the eccentric cam 19 rotates clockwise about the shaft 20, as shown in FIG. is pulled to the right.

That is, on the lower surface of the control slider 12, the point of contact with the roller 16 of the jet 11 moves away from the eccentric cam 19, and the effective length L of the control slider 12 becomes longer.

Therefore, the stroke of the bushing rod 24 connected to the upper surface of the -end side of the control slider 12 is small, and the speed of the bushing rod 24 is slow, so that the unit injector cannot be used during high-speed operation. The fuel injection pressure of the unit injector is maintained at a high pressure without exceeding the limit pressure of the unit injector, and damage to the unit injector is prevented.

Of course, in the above-mentioned operation, the bushing rod 2
The lower end of the dash rod 24 is moved by the control slider 12, and the inclination angle of the dash rod 24 changes slightly, but the range of movement of the lower end of the bush rod 24 is as follows:
The inclination of such dash rod 24 has very little effect on the rotation of the anchor arm, as it is very slight compared to the length of dash rod 24.
child.

Therefore, the fuel injection pressure at the unit injector is properly controlled.

According to the above invention, a tappet for transmitting the movement of a cam of a cam shaft disposed in a diesel engine to a bushing rod so as to drive a cam follower of a unit injector; a control slider disposed between the bushing rod and the lower end of the bushing rod rotatably connected to the control slider;
The dash rod includes an actuator that rotatably supports the control slider and makes it reciprocate, and is configured to change the stroke of the dash rod depending on the position where the control slider is reciprocated. , when a diesel engine is operating at low speed, the fuel injection pressure at the unit injector increases, improving combustion efficiency, and when the diesel engine is operating at high speed, the fuel injection pressure exceeds the limit pressure of the unit injector. The unit injector is maintained at a high pressure without being exceeded, and damage to the unit injector is prevented.Moreover, such injection pressure control is performed by simple means, making it extremely practical.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram showing a specific example of the fuel injection control device used in the unit injector of the present invention, FIG. 2 is a schematic diagram showing the fuel injection control device during low speed operation of a diesel engine, and FIG. The figure is a schematic diagram showing a fuel injection control device during high-speed operation of a diesel engine. DESCRIPTION OF SYMBOLS 10... Fuel injection control device used for a unit injector, 11... Control slider, 13... Cam shaft, 14...
・Cam, 24...butshu rod 〇if-, ITJ
ZJ, Yuho 2 drawing, Saku 3 drawing

Claims (1)

[Claims] A tappet for transmitting the movement of a cam of a cam shaft disposed in a diesel engine so as to drive a cam follower of a unit injector; Used for a unit injector that includes a control slider that is arranged between the bushings and the lower end of the bushing rod is rotatably connected to the control slider, and an actuator that rotatably supports the control slider and causes it to reciprocate. fuel injection control device.