JPH04325726A - Fuel injector - Google Patents

Abstract

PURPOSE:To return a fuel injection amount adjusting member to a non-injection position precisely by operating force generated by a hydraulic piston when stop of a diesel engine is necessitated. CONSTITUTION:Under a normal condition, a fuel injection amount adjusting member 4 for adjusting a fuel injection amount is moved to an injection amount adjusting position by an actuator driven by an outer signal. When it is in an emergency condition, the fuel injection amount adjusting member 4 is moved to a non-injection position by oil pressure of an oil pressure chamber 6 forcibly. Namely, the fuel injection amount adjusting member 4 is moved to the non- injection position by operating force generated by rising of pressure in the oil pressure chamber 6, and then, after an engine is stopped in association therewith, pressure in the oil pressure chamber 6 is reduced. When the rotational number of an engine reaches the level of 0 completely, electrification of an electromagnetic valve 13 is disconnected, and the flow passage of operating oil is sealed. After that, operating oil remaining in the oil pressure chamber 6 is returned to an oil reservoir chamber 10 by an oil returning passage 15 passing a restriction 14.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuel injection system for a diesel engine, and more particularly to a fuel injection system in which a hydraulic piston returns a fuel injection amount adjusting member to a non-injection position when the engine is stopped.

0002

BACKGROUND OF THE INVENTION A conventional method for stopping a diesel engine is to push the fuel injection amount adjusting member back to the no-injection position using a stop lever.
Stopping a diesel engine is complicated because the driver has to turn off the key switch and operate the stop lever at the same time. The method of stopping a diesel engine that uses an electronically controlled governor device is usually a linear DC system that generates operating force in the direction of the fuel source at the same time as the key switch is turned off.
Electric current is supplied to the motor, and the linear DC motor moves the fuel injection amount adjusting member to a no-injection position, cutting off fuel supplied to the engine.

0003

[Problems to be Solved by the Invention] However, according to the conventional fuel injection system for diesel engines that uses an electronically controlled governor device, the operation of the linear DC motor is limited due to restrictions such as the ability to mount the fuel injection pump on the diesel engine. If the linear DC motor is installed tilted in a direction other than the vertical direction, if current is not supplied to the linear DC motor due to a failure in the control circuit, the weight of the linear DC motor's operating shaft will move the operating shaft to the non-injection position. As a result, there is a risk that the vehicle may run out of control.

As a means to solve this problem, it is conceivable to provide a return spring inside the governor and use the repulsive force of this return spring to push the fuel injection amount adjusting member back to the no-injection position. However, since the linear DC motor must be operated in a direction against the return spring, there is a problem in that the force for operating the fuel injection amount adjusting member is reduced to the extent that the operating force of the linear DC motor is reduced.

The present invention has been made to solve these problems, and when it is necessary to stop the diesel engine, the fuel injection amount adjusting member is accurately moved to the non-injection position by the actuation force generated by the hydraulic piston. The object of the present invention is to provide a fuel injection device that allows the fuel injection device to return to

[0006]

[Means for Solving the Problems] A fuel injection device according to the present invention for solving the above problems pressurizes fuel by reciprocating motion of a plunger, and pumps the pressurized fuel from a delivery valve to an internal combustion engine. In the injection device,
A fuel injection amount adjustment member that adjusts the fuel injection amount, an actuator that drives the fuel injection amount adjustment member to an injection amount adjustment position based on an external signal, and a hydraulic piston that forcibly moves the actuator to a no-injection position. A throttle that maintains the hydraulic oil in the hydraulic chamber in the cylinder that slidably accommodates the hydraulic piston at a predetermined value or higher when the hydraulic piston is activated, and releases the hydraulic oil in the hydraulic chamber to the outside after the hydraulic piston is activated. It is characterized by having the following.

[0007]

[Operation] According to the fuel injection device of the present invention, since the fuel injection amount adjusting member is provided with a hydraulic circuit in which hydraulic pressure acts in the direction of fuel reduction, the injection amount adjusting member is always disabled when the key switch of the diesel engine is turned off. Return to the injection position and make sure to stop the diesel engine.

[0008]

Embodiments Hereinafter, embodiments of the present invention will be explained based on the drawings. A first embodiment in which the present invention is applied to an in-line fuel injection pump for a diesel engine is shown in FIG. The governor 2 fixed to the injection pump body 1 has a built-in linear DC motor type actuator 3.
is connected to a fuel injection amount adjusting member 4 that controls the fuel injection amount. This fuel injection amount adjusting member 4 has one end 4a
is interlocked with the moving coil of the actuator 3.

Tip portion 4 on the other end side of the fuel injection amount adjusting member 4
b has a cylindrical shape, and is slidably fitted into the cylindrical inner circumferential wall 5 of the injection pump body 1 . A hydraulic chamber 6 is formed by the cylinder inner circumferential wall 5 and the front end surface 4d of the fuel injection amount adjusting member 4. Fuel injection amount adjustment member 4
The area on which the hydraulic pressure acts on the tip surface 4d is selected so as to generate enough hydraulic pressure to overcome the sliding resistance during operation of the fuel injection amount adjusting member 4 and the linear DC motor 3 and move the control rack 4. ing. An annular groove 4c formed on the outer periphery of the tip 4b of the fuel injection amount adjusting member 4 is
A ring 7 is attached, and this O-ring 7 prevents hydraulic oil from flowing into the injection pump body 1 from the hydraulic chamber 6. In this first embodiment, lubricating oil from a diesel engine is used as the hydraulic oil.

The hydraulic circuit that supplies hydraulic oil to the hydraulic chamber 6 is as follows:
It is configured as shown in FIG. When the solenoid valve 13 is open, the hydraulic oil pumped up from the oil reservoir chamber 10 by the hydraulic pump 11 flows through the oil supply passage 12, the solenoid valve 13, and the oil supply passage 1.
6 and is supplied to the hydraulic chamber 6. The hydraulic oil in the hydraulic chamber 6 passes through the throttle 14 and is returned to the oil reservoir chamber 10 through an oil return passage 15. In this case, the solenoid valve 13 is of a normally open type, and when energized, the electromagnetic attraction force generated by the excitation of the solenoid attracts the valve element to close the oil flow path, thereby blocking the flow of hydraulic oil. When the electromagnetic valve 13 is not energized, the urging force of the spring opens the valve body and allows the hydraulic oil to flow.

[0011] The hydraulic oil that flows out when the solenoid valve 13 is open is guided into the hydraulic chamber 6 from the inlet portion 6a of the hydraulic chamber 6. A throttle 14 is provided at the outlet portion 6b of the hydraulic chamber 6, and this throttle 1
The inner diameter of 4 is the hydraulic chamber 6 pressurized by the hydraulic pump 11.
The hydraulic pressure inside the hydraulic chamber 6 is small enough not to drop below a predetermined value, and large enough so that the oil in the hydraulic chamber 6 can be discharged to the outside through the oil return passage 15 immediately after the hydraulic pump 11 stops. The inner diameter of the diaphragm 14 is selected, for example, from a range of 0.5 to 1.0 mm. The solenoid valve 13, which operates in conjunction with a key switch (not shown), is energized and closed when the key switch is turned on, thereby blocking the flow of hydraulic oil. When the key switch is turned off, the electromagnetic valve 13 is de-energized and the return spring opens the valve body to allow hydraulic oil to flow. As a result, the oil pressure in the hydraulic chamber 6 is increased, and the fuel injection amount adjusting member 4 is forcibly moved to the right in FIG. 1 by the operating force of this oil pressure, thereby reducing the fuel injection amount to zero.

Next, the operation will be explained. Normally, no current is supplied to the solenoid valve 13, so its built-in spring closes the flow path for the hydraulic fluid in the hydraulic circuit. For example, when the diesel engine reaches a dangerous rotation range, the solenoid valve 13 is activated by a command from an emergency stop circuit in a control device (not shown).
Current is supplied to Then, the engine lubricating oil pumped by the hydraulic pump 11 flows from the oil supply passage 12 through the electromagnetic valve 13 and the oil supply passage 16 into the hydraulic chamber 6 by the opening operation of the solenoid valve 13. As the oil pressure in the hydraulic chamber 6 increases, an operating force is generated in the fuel injection amount adjusting member 4 in the direction of decreasing the injection amount, that is, in the direction of arrow A shown in FIG. When the fuel injection amount adjusting member 4 is moved to the no-injection position due to the pressure increase in the hydraulic chamber 6, the fuel to the engine is cut off, the engine speed is reduced, and the hydraulic pressure pressurized by the hydraulic pump 11 is accordingly reduced. also decreases. At this time, since the solenoid valve 13 is open, the internal pressure of the hydraulic chamber 6 also decreases.

[0013] When the engine speed becomes completely zero, the electromagnetic valve 13 is de-energized and the hydraulic oil passage is closed. After that, the hydraulic oil remaining in the hydraulic chamber 6 is removed from the throttle 14.
The oil is returned to the oil reservoir chamber 10 through the oil return passage 15. As a result, since the residual pressure of the hydraulic pressure in the hydraulic chamber 6 is sufficiently reduced after the engine is stopped, the operation of the fuel injection amount adjusting member 4 is not hindered when the engine is restarted.

Next, a second embodiment in which the present invention is applied to a fuel injection pump for a diesel engine is shown in FIG. The second embodiment is an example in which a fuel pressure pump 20 is used in place of the hydraulic pump 11 of the first embodiment. That is, the fuel pressure pump 2
0 through the fuel supply passages 21 and 22 to the fuel inlet 2
Fuel is supplied into the injection pump main body 1 from 3. A solenoid valve 13 is provided in the middle of a fuel introduction passage 26 that branches off from the fuel supply passage 21 . The other constituent parts are the same as those in the first embodiment, so substantially the same constituent parts are given the same reference numerals and the explanation thereof will be omitted. When the electromagnetic valve 13 is opened, the pressurized fuel supplied from the fuel pressure pump 20 to the fuel supply passage 21 flows into the hydraulic chamber 6 through the fuel introduction passage 26. The action of the fuel after it flows into the hydraulic chamber 6 is the same as that of the hydraulic fluid in the first embodiment, so a description thereof will be omitted.

In the first and second embodiments described above, the hydraulic pump 11 and the fuel pressure pump 20 were used as the hydraulic pressure source of the hydraulic circuit, but other pumps may be used as the hydraulic oil pressure source of the present invention. Of course, you may also use .

[0016]

As explained above, according to the fuel injection device of the present invention, in an emergency such as when the internal combustion engine reaches a dangerous range, the injection amount adjusting member is forced to the no-injection position by hydraulic pressure. Since it is configured to move, when an abnormality occurs in the actuator of the fuel injection pump, fuel injection from the fuel injection pump is reliably stopped and the internal combustion engine is completely stopped.
This has the effect of increasing the safety of the internal combustion engine. Furthermore, when restarting after an emergency occurs, the hydraulic chamber has been returned to its initial state, which has the effect of not interfering with the next restart.

[Brief explanation of drawings]

FIG. 1 is a schematic configuration diagram showing a fuel injection pump according to a first embodiment of the present invention.

FIG. 2 is a schematic configuration diagram showing a fuel injection pump according to a second embodiment of the present invention.

[Explanation of symbols]

3 Actuator 4 Fuel injection amount adjusting member (hydraulic piston) 5 Cylinder inner wall 6 Hydraulic chamber 14 Throttle

Claims (1)

[Claims] 1. A fuel injection device that pressurizes fuel by reciprocating motion of a plunger and force-feeds the pressurized fuel from a delivery valve to an internal combustion engine, comprising: a fuel injection amount adjustment member that adjusts a fuel injection amount; an actuator that drives an injection amount adjustment member to an injection amount adjustment position by an external signal; a hydraulic piston that forcibly moves the actuator to a no-injection position; and when the hydraulic piston is activated, this hydraulic piston is slidably accommodated. 1. A fuel injection device comprising: a throttle that maintains hydraulic oil in a hydraulic chamber in a cylinder at a predetermined value or higher and releases the hydraulic oil in the hydraulic chamber to the outside after actuation of a hydraulic piston.