JPH0343466B2 - - Google Patents

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 the 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 usually determined by the rotational speed of the camshaft that reciprocates the follower of the unit injector.
and is determined by the shape of the cam in the cam shaft.

However, when the diesel engine is operated at low speed, the fuel injection pressure at the unit injector is relatively low, which tends to reduce combustion efficiency, and when the diesel engine is operated at high speed, the unit injector - Since the fuel injection pressure at the injector rose to an extremely high pressure, it exceeded the limit pressure of the unit injector and there was a risk that the unit injector would be damaged.

Also, JP-A-49-70031, JP-A-56-
No. 38532 and Japanese Patent Application Laid-Open No. 57-65806 disclose fuel injection timing adjustment devices for diesel engines, but these adjustment devices do not allow the adjustment of the cam and the cam follower, or the intermediate roller. Accurate adjustment has been difficult because the contact point is moved in a direction perpendicular to the cam axis as the cam follower or intermediate roller moves.

The purpose and problem of this invention is to increase the fuel injection pressure of a unit injector during low speed operation of a diesel engine to improve combustion efficiency, and to increase the fuel injection pressure to the unit injector during high speed operation of the diesel engine. It is possible to maintain high pressure without exceeding the limit pressure of the unit, prevent damage to the unit injector, and use extremely simple means.
An object of the present invention is to provide a fuel injection control device used in a unit injector that accurately controls fuel injection pressure.

In connection with the above-mentioned objects and problems, the fuel injection control device used in the unit injector of the present invention is brought into contact with a cam of a cam shaft disposed in a diesel engine, and is in contact with a cam of a cam shaft disposed in a diesel engine, and A tappet that transmits the movement of the cam to the push rod side that drives the follower of the unit injector is pivotally connected to one end of the push rod, and the other end is rotatably supported by an eccentric cam. The slider is placed between the rod and its tappet, and when the engine is running at low speed, the effective length of the slider up to the point of contact with the tappet is shortened to increase the fuel injection pressure. During operation, the effective slider length up to the point of contact with the tappet is lengthened to rotate the control slider and its eccentric cam to maintain the fuel injection pressure at a high pressure without exceeding the limit pressure of the unit injector. and an actuator for reciprocating the control slider.

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

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

The fuel injection control device 10 contacts a cam 14 of a cam shaft 13 disposed in a diesel engine, and a push rod 24 that drives a follower of a unit injector via a rocker arm (not shown). The tappet 11 that transmits the movement of the cam 14 to the side is pivotally connected to the push rod 24 at one end, and the other end is rotatably supported by the eccentric cam 19 to connect the push rod 24 and the tappet 11. When the engine is running at low speed, the effective length of the slider up to the point of contact with the tappet 11 is shortened to increase the fuel injection pressure, and when the engine is running at high speed, the effective length of the slider up to the point of contact with the tappet 11 is shortened. A control slider 12 whose effective slider length up to the point of contact with the unit injector 11 is lengthened to maintain the fuel injection pressure at a high pressure without exceeding the limit pressure of the unit injector, and a control slider 12 that rotates its eccentric cam to control it. - Manufactured with an actuator that reciprocates the slider.

The tappet 11 is fitted into a tappet bore 28 formed in the cylinder head 27 at a position corresponding to the upper part of the cam 14 in the cam shaft 13 of a diesel engine so as to be able to reciprocate vertically. Rollers 15, 16 at the upper end
are arranged so that they can rotate.

Of course, the rollers 15, 16 project outside the tappet bore 28, ie, to the lower and upper sides, respectively.

The roller 15 contacts the cam surface 14 of the cam shaft 13, and as the cam shaft 13 is rotated, the tappet 11 is reciprocated in the vertical direction.

The control slider 12 is arranged horizontally with the lower surface of one end resting on the roller 16 of the tapepet 11, and has an eccentric cam 19 rotatably arranged at the other end.

That is, the control slider 12
is a connecting part 1 with a circular bore 18 at the other end.
7 is integrally formed, and an eccentric cam 19 is rotatably fitted into the bore 18 thereof.

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

Further, the control slider 12 is provided with a ball seat 23 on the upper surface of one end, and the ball portion 25 at the lower end of the push rod 24 is accommodated in the ball seat 23.

Therefore, the control slider 12 is
It is arranged horizontally 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 attached to the cylinder head 27, and further,
Ball seat 23 formed on the upper surface of one end
, the ball part 2 at the bottom of the push rod 24
Contains 5.

Of course, the upper end of the push rod 24 is connected to the end of a rocker arm (not shown) rotatably disposed in the cylinder head 27 for pushing the follower of the unit injector.

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

That is, the actuator connects a cylinder (not shown) disposed on the cylinder head side of the control slider 12 in the vicinity of the eccentric cam 19 of the control slider 12.
It consists of a piston (not shown) fitted into a bore so as to be able to reciprocate and slide, and 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 operating rod 22 end of the actuator is connected to the shaft 2 of the eccentric cam 19 via a link 21.
Connected to 0.

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

Therefore, if the actuator is driven, the eccentric cam 19 is connected via the link 21.
rotates about the shaft 20, and the rotation of the eccentric cam 19 causes the control slider 12 to reciprocate with rotational motion.

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);
The solenoid valve is controlled by a controller (not shown).

The controller controls the solenoid valve according to a preset fuel injection pattern in response to a signal from the diesel engine's rotation speed sensor (not shown), and mainly consists of input and output circuits, memory It consists of a circuit, an arithmetic circuit, and a control circuit.

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

Next, to describe the operation of the above-mentioned fuel injection control device 10, when the diesel engine is operating, the cam
The shaft 13 rotates, the tappet 11 reciprocates vertically in accordance with the rotation of the cam shaft 13, and the control slider 12 moves the eccentric cam 1.
Rotate around 9.

That is, the movement of the tapepet 11 is guided to the unit injector via the push rod 24 and 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 moves onto the shaft 20, as shown in FIG.
Such rotation of the eccentric cam 19 forces its control slider 12 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 effective slider length L of the control slider 16 becomes shorter.

Therefore, the stroke of the push rod 24 connected to the upper surface of one end side of the control slider 12 becomes larger, and the push rod 24 becomes larger.
Since the speed of the rod 24 is increased, the fuel injection pressure at the unit injector during low speed operation is increased and combustion efficiency is improved.

When the diesel engine operates at high speed, the controller controls the solenoid valve, drives the actuator, and retracts the operating rod 22.

When the operating rod 22 is retracted, the third
As shown in the figure, the eccentric cam 19
0, and such rotation of the eccentric cam 19 pulls its control slider 12 to the right.

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

Therefore, the stroke of the push rod 24 connected to the upper surface of one end of the control slider 12 becomes smaller, and the push rod 24 becomes smaller.
Since the speed of the rod 24 is reduced, the fuel injection pressure at the unit injector during high-speed operation is maintained at a high pressure without exceeding the limit pressure of the unit injector, and damage to the unit injector is prevented. Ru.

Of course, in the above-mentioned operation, the push button
The lower end of the rod 24 is the control slider 12
The push rod 24 moves by the push rod 24, and the inclination angle of the push rod 24 changes slightly, but the range of movement of the lower end of the push rod 24 is extremely small compared to the length of the push rod 24. ,
Such inclination of the push rod 24 has little effect on the rotation of the rocker arm, and the fuel injection pressure at the unit injector is properly controlled.

As understood from the above, the fuel injection control device used in the unit injector of the present invention is brought into contact with the cam of the cam shaft disposed in the diesel engine, and is connected to the unit injector via the rocker arm. A tappet that transmits the movement of the cam to the push rod that drives the follower of the injector is pivotally connected to one end of the push rod, and the other end is rotatably supported by an eccentric cam. When the engine is running at low speed, the effective length of the slider up to the point of contact with the tappet is shortened to increase the fuel injection pressure, and when the engine is running at high speed, , a control slider whose effective slider length up to the point of contact with the tappet is lengthened to maintain the fuel injection pressure at a high pressure without exceeding the limit pressure of the unit injector, and a control slider whose eccentric cam is rotated to The unit includes an actuator that reciprocates the control slider, so when the diesel engine is operating at low speed, the unit
The fuel injection pressure of the injector is increased to improve combustion efficiency, and when the diesel engine is operating at high speed, the fuel injection pressure of the unit is increased.
The unit injector is maintained at high pressure without exceeding its critical pressure, thereby preventing damage to the unit injector, and furthermore, the point of contact between the tappet and its cam is on the axis of the tappet passing through the axis of the cam. As a result, the fuel injection pressure can be controlled easily and with high precision, 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. 10... Fuel injection control device used in unit injector, 11... Tappet, 12... Control slider, 13... Cam shaft, 14
...Kam, 24...Putshiyu Rodsud.

Claims (1)

[Claims] 1. The cam is brought into contact with the cam of the cam shaft disposed in the diesel engine, and the movement of the cam is transmitted to the push rod side which drives the follower of the unit injector via the rocker arm. The push rod is pivotally connected to the push rod at one end, and the other end is rotatably supported by an eccentric cam, and is disposed between the push rod and the tappet. ,
The effective slider length up to the point of contact with the tappet is shortened to increase the fuel injection pressure, and when the engine is running at high speed, the effective slider length up to the point of contact with the tappet is lengthened to increase the fuel injection pressure. The control slider maintains the fuel injection pressure at high pressure without exceeding the unit injector's limit pressure, and the control slider rotates the eccentric cam.
A fuel injection control device used in a unit injector including an actuator that reciprocates a slider.