JPH0340234B2 - - 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 of 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 of the unit 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.

In addition, as a fuel injection control device for a diesel engine, Japanese Patent Application Laid-Open No. 56-38531 and Utility Model Application No. 57-
Although disclosed in Japanese Patent No. 109271, it was necessary to connect the hydraulic cylinder to the eccentric shaft through a link means such as a lever, and to make the actuator a special structure.

The object and problem of this invention is to increase the fuel injection pressure of the unit injector during low-speed operation of a diesel engine to improve combustion efficiency, and to increase the fuel injection pressure of the unit injector during high-speed operation of the diesel engine. It maintains high pressure without exceeding the limit pressure, prevents damage to the unit injector, and also eliminates the need for a specially constructed actuator and link means such as levers to connect the actuator. The object of the present invention is to provide a fuel injection control device for use in a unit injector that can control such fuel injection pressure by an extremely simple means and reduce production costs.

In connection with the above objects and problems, the fuel injection control device used in the unit injector of the present invention includes a cam fixedly supported on the cam shaft of a diesel engine and a push rod for driving the unit injector. and a control slider having a bore at the other end, and a control slider having one end side arranged between the control slider and the control slider so that the push rod can move up and down according to the rotation of the cam, and a control slider having a bore at the other end, and a control slider that can rotate around the bore of the control slider. It includes an eccentric cam to be fitted, a slider control shaft that supports the eccentric cam by a helical spline connection, and a linear motion actuator that reciprocates the slider control shaft in the axial direction, and , a cam that is fixedly supported on the cam shaft of a diesel engine and a pusher that drives a unit injector.
One end of the push rod is placed between the push rod and the push rod, and the push rod can be moved up and down according to the rotation of the cam, and the control rod has a bore at the other end.
A slider, an eccentric cam that is rotatably fitted into the bore of the control slider, a slider control shaft that supports the eccentric cam by a helical spline connection, and a reciprocating motion of the slider control shaft in the axial direction. The diesel engine includes a hydraulic cylinder, a solenoid valve that supplies and discharges pressure oil to and from the hydraulic cylinder, and a controller that controls the current flowing through the solenoid valve in accordance with the rotation speed of the diesel engine.

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

1 and 2 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 10 includes a cam 22 fixedly supported on a cam shaft 21 of a diesel engine to drive a cam follower of a unit injector (not shown) disposed on the diesel engine. Push the movement 23
One end of the tapepet 11 is placed between the tapepet 11 and the push rod 23, and as the cam 22 rotates, the push rod
The rod 23 is made vertically movable, and the bore 19
a control slider 12 having at the other end;
An eccentric cam 13 rotatably fitted into the bore 19 of the control slider 12, and a slider control shaft 14 supporting the eccentric cam 13 by helical spline connection.
and its slider control shaft 14
It was manufactured to include a linear motion actuator (not shown) that reciprocates in the axial direction.

The tappet 11 is capable of reciprocating vertically in a tappet bore 25 formed in the cylinder head 20 at a position corresponding to above the cam 22 which is fixedly supported by the cam shaft 21 of the diesel engine. The rollers 15 and 16 are rotatably disposed at the lower and upper ends, respectively.

Of course, the rollers 15, 16 project outside the tappet bore 25, ie, to the lower and upper sides, respectively.

Therefore, the tapepet 11 has its lower roller 15 mounted on the cam 22 of its cam shaft 21, and as the cam shaft 21 is rotated, it is reciprocated in the vertical direction.

The control slider 12 is disposed laterally with one end resting on the roller 16 above the tappet 11 so as to receive the lower end of the push rod 23, and is provided with a bore 19 at the other end.

That is, the control slider 12
is configured in a lever shape so that it can be placed horizontally on the roller 16 above the tapepet 11, and the upper part near one end receives the ball part 24 at the lower end of the push rod 23. Forming a ball seat 17, and at the other end,
A connecting portion 18 having a circular bore 19 is integrally formed.

The eccentric cam 13 is rotatably fitted in the bore 19 of the control slider 12.

Of course, the eccentric cam 13 is rotatably fitted into the bore 19 so that its movement in the axial direction is restricted.

Moreover, the eccentric cam 13 is
A helical spline groove 26 for a slider control shaft 14, which will be described later, is provided at a position offset from the center to one side.

The slider control shaft 14 is helically splined to its eccentric cam 13.

That is, the slider control shaft 14 is a helical spline shaft having a helical spline on one end side, and is arranged laterally so as to be substantially orthogonal to the control slider 12, and its eccentricity is The eccentric cam 13 is helically spline connected to the helical spline groove 26 of the eccentric cam 13 so as to be biased to one side from the center of the cam 13.

Therefore, if the slider control shaft 14 is moved in the axial direction, the eccentric cam 13 will be rotated with the movement of the slider control shaft 14; That control
Slider 12 is moved laterally.

Of course, the eccentric cam 13 is arranged on both end faces of the eccentric cam 13 and fixed to the cylinder head so that the slider control shaft 14 does not move in the axial direction when the slider control shaft 14 is reciprocated. Axial movement is restricted by a retainer (not shown).

The linear motion actuator is a hydraulic cylinder, and the slider control shaft 1
4, and reciprocates its slider control shaft 14 in the axial direction depending on the operating conditions of the diesel engine.

That is, the hydraulic cylinder includes a cylinder body disposed in the cylinder head of the diesel engine, a piston fitted into the cylinder bore of the cylinder body so as to be able to slide back and forth, and one end of the cylinder body disposed in the cylinder head. and the other end is connected to the piston, and the slider control shaft 14 is connected to the piston.
The slider control shaft 14 was assembled to include an operating rod disposed coaxially with the slider control shaft 14 and having one end thereof connected to one end of the slider control shaft 14.

Further, this hydraulic cylinder is connected to an oil pump (not shown) driven by the diesel engine through a hydraulic piping (not shown), and a solenoid valve (not shown) disposed in the hydraulic piping. Pressure oil is supplied and discharged. Of course, the opening/closing of the solenoid valve is controlled by a current supplied by a controller (not shown) according to the rotational speed of the diesel engine.

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

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

The upper end of the push rod 23 is connected to the end of a rocker arm (not shown) rotatably disposed in the cylinder head 20 so as to push the follower of the unit injector.

Next, the operation of the fuel injection control device 10 described above will be described. When the diesel engine is operating, the cam shaft 21 rotates, and the tappet 1
1 is reciprocated in the vertical direction by its cam 22 in accordance with the rotation of its cam shaft 21, and the control slider 12 rotates around the eccentric cam.

That is, the movement of the tapepet 11 is guided to the unit injector via the push rod 23 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 moves the slider control shaft 14 in the direction of arrow A in FIG. Ru.

When the slider control shaft 14 is so moved, the eccentric cam 13 is rotated counterclockwise about the shaft 14;
Such rotation of the eccentric cam 13 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 13, and the effective length L of the control slider 12 becomes shorter.

Therefore, the push rod 2 connected to the upper surface of one end side of the control slider 12
Since the stroke of No. 3 becomes larger and the speed of the push rod 23 becomes faster, 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 solenoid valve is controlled by the controller, and the actuator is driven to move the slider control shaft 14 in the opposite direction to that described above.

Such movement of the slider control shaft 14 causes the eccentric cam 13 to rotate clockwise about the shaft 14, and such rotation of the eccentric cam 13 causes the control slider 12 to rotate clockwise. pulled 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 13, and the effective length L of the control slider 12 becomes longer.

Therefore, the push rod 2 connected to the upper surface of one end side of the control slider 12
3 becomes smaller and the speed of the push rod 23 becomes slower, so that the fuel injection pressure at the unit injector during high-speed operation does not exceed the limit pressure of the unit injector, and the pressure is increased. to prevent damage to the unit injector.

Of course, in the above-described operation, the lower end of the push rod 23 is moved by the control slider 12, and the inclination angle of the push rod 23 changes slightly. Since the range of movement of the unit is extremely small compared to the length of the push rod 23, such inclination of the push rod 23 has little effect on the rotation of the rocker arm, and the unit・The fuel injection pressure at the injector is appropriately controlled.

In the above-described fuel injection control device 10, the slider control shaft 14 is connected to the eccentric cam 13 by a helical spline, and when the slider control shaft 14 is moved in the axial direction, the control slider 12 The effective length L of the actuator can be changed by changing the actuator's operating rod to its slider control.
Can be directly connected to the shaft 14 end,
In other words, the slider control
A link mechanism is not required in the drive system of the shaft 14, and the structure is simplified.

As understood from the above, the fuel injection control device used in the unit injector of the present invention includes a cam fixedly supported on the cam shaft of a diesel engine and a push rod that drives the unit injector. One end of the push rod is arranged in between, the push rod is movable up and down in response to the rotation of the cam, and the push rod is rotatably fitted into the control slider having a bore at the other end. The present invention includes an eccentric cam, a slider control shaft that supports the eccentric cam by a helical spline connection, and a linear motion actuator that reciprocates the slider control shaft in the axial direction. One end is placed between a cam that is fixedly supported on the cam shaft of a diesel engine and a push rod that drives a unit injector, and the push rod is movable up and down in accordance with the rotation of the cam. , a control slider having a bore at the other end, and an eccentric cam rotatably fitted in the bore of the control slider;
A slider control shaft that supports the eccentric cam with a helical spline connection, a hydraulic cylinder that reciprocates the slider control shaft in the axial direction, a solenoid valve that supplies and discharges pressure oil to and from the hydraulic cylinder, and Since the fuel injection control device used in the unit injector of the present invention includes a controller that controls the current flowing through the solenoid valve according to the rotation speed of the diesel engine, the control slider is The stroke of the push rod is changed according to the movement, and when the diesel engine is operating at low speed, the fuel injection pressure of the unit injector is increased, improving combustion efficiency, and when the diesel engine is operating at high speed, the fuel injection pressure is increased. The pressure is maintained at a high level without exceeding the limit pressure of the unit injector, preventing damage to the unit injector, and the eccentric cam provides a helical connection to the slider control shaft.
Because it is supported by a spline connection, the linear motion actuator can be connected directly to the end of the slider control shaft without using a specially constructed actuator or linking means such as a lever to connect the actuator. This makes it possible, the structure is extremely simple, the optimum fuel injection pressure can be easily obtained by simple means according to the operating conditions of the diesel engine, the production cost is low, and it is extremely practical.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram showing a specific example of a fuel injection control device used in the unit injector of the present invention, and FIG. 2 is a perspective view of the control slider shown in FIG. 1. 11... Tappet, 12... Control slider, 13... Eccentric cam, 14... Slider
Control shaft, 19...Bore, 21...
...Kam Shaft, 22...Kam, 23...Push Rod.

Claims (1)

[Scope of Claims] 1. One end side is disposed between a cam fixedly supported on the cam shaft of a diesel engine and a push rod that drives a unit injector, and the push rod is moved in accordance with the rotation of the cam. - A control slider that allows the rod to move up and down and has a bore at the other end, an eccentric cam that is rotatably fitted into the bore of the control slider, and a slider that supports the eccentric cam with a helical spline connection. - A fuel injection control device used in a unit injector that includes a control shaft and a linear motion actuator that reciprocates the slider control shaft in the axial direction. 2 One end is placed between a cam that is fixedly supported on the cam shaft of a diesel engine and a push rod that drives a unit injector, and the push rod can be moved up and down according to the rotation of the cam. and a control slider having a bore at the other end, an eccentric cam rotatably fitted into the bore of the control slider, and a slider control shaft supporting the eccentric cam by a helical spline connection. A hydraulic cylinder that reciprocates the slider control shaft in the axial direction, a solenoid valve that supplies and discharges pressure oil to and from the hydraulic cylinder, and a controller that controls the current flowing through the solenoid valve according to the rotation speed of the diesel engine. A fuel injection control device used in a unit injector including