JPH0560033A - Fuel injection device for internal combustion engine - Google Patents

Abstract

PURPOSE:To regulate injection timing in a simple constitution by opening a barrel with two ports for operation and for starting, respectively, and providing the port for operation with a valve connected with an actuator which is actuated only in starting. CONSTITUTION:For a fuel injection pump of a diesel engine, a cylindrical barrel 14 is fixed in a pump case 1, and a plunger 15 is inserted therein, while a valve case is fixed to the pump case 1, with a delivery valve installed in it. In this case, a port A for operation and a port B for starting are provided at an upper side surface of the barrel 14, and the operation port A be opened/closed by a valve 10. The valve 10 is driven and controlled by a CPU 12 through an actuator 11 to be closed when the engine 13 is started, so fuel is supplied only from the starting port B which is opened at a higher position than the port A, thereby an injection timing is set earner.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a structure for advancing fuel injection timing only when starting a diesel engine.

[0002]

2. Description of the Related Art Conventionally, in a diesel engine in which fuel injection timing is kept constant, it is constant from low speed to high speed. For example, as shown in FIGS. 5 and 6, the fuel injection pump has a cylindrical barrel 2 fixed in a pump case 1,
The plunger 3 is inserted into the barrel 2 and the valve case 6 is fixed to the upper part of the pump case 1 to fix the delivery valve 4
The delivery valve 4 is biased in the closing direction by a spring, and the upper end of the valve case 6 is communicated with the injection nozzle. The fuel supply port 7 is provided on the side surface of the pump case 1.
And communicates with a fuel chamber 8 provided around the upper portion of the barrel 2, and the fuel chamber 8 has a port 2 formed in the barrel 2.
The cavitation deflector 9 is disposed so as to communicate with the port a and face the port 2a.

Further, a communication groove 3a for communicating with the compression chamber C on the delivery valve 4 side is formed around the side surface of the plunger 3, and when the communication groove 3a and the port 2a communicate with each other, the pressure feeding is terminated. That is, FIG. 6 shows the communication groove 3a unfolded. When the plunger 3 descends to the lower end, the fuel is sucked into the barrel 2 from the port 2a, the plunger 3 rises, and the side surface of the plunger 3 moves to the port. When 2a is closed, the fuel is compressed, the delivery valve 4 is opened, and the fuel is pressure-fed to the injection nozzle side. And the communication groove 3
When a and port 2a coincide with each other, fuel returns from the communication groove 3a to the fuel chamber 8 and the pressure feeding is completed. The plunger 3 is interlocked with the governor, and the plunger 3 is rotated with an increase in the number of revolutions so that the pressure feeding time of fuel is shortened. With such a configuration, the pumping start timing was set to be the same from the start to the high speed operation.

In recent years, however, environmental problems have come to be widely taken up, and NOx reduction has been attempted. Therefore, as shown in FIG. 7, in the diesel engine, the injection timing can be retarded most easily in order to reduce NOx, so that the injection timing is gradually set later. .

[0005]

However, although it is possible to operate without problems even if the injection timing is set late so as to reduce NOx during normal operation, ignition will not occur if the fuel injection timing is delayed during startup. There was knocking. In order to secure the startability with the upper lead, the fuel injection pump having only one barrel in the barrel of the conventional fuel injection pump (two in the opposed plunger having a pressure balance) cannot secure the optimum injection timing at the start. Since it could not be done, it was necessary to make major changes such as twisting the cam shaft on the engine side or configuring it as a swing arm with an eccentric cam.

[0006]

In order to solve such a problem, the present invention has a fuel injection pump in which two ports for operation and for starting are opened in the barrel for operation. The port is provided with a valve, the valve is connected to an actuator, the actuator is operated only at the time of starting, and the port for operation is closed.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The problem to be solved by the present invention and the means for solving the problems are as described above. Next, the structure of the embodiment shown in the accompanying drawings will be described. FIG. 1 shows a part of a fuel injection pump. FIG. 4 is a sectional view, FIG. 2 is a perspective view of a barrel, FIG. 3 is a developed view of a plunger, and FIG. 4 is a sectional view showing another embodiment of the valve placed in FIG.

In FIG. 1, a pump case 1, a delivery valve 4, a valve case 6 and the like have the same structure as the conventional one shown in FIG. 5, and a valve 10 is provided in the pump case 1 instead of the cavitation deflector 9.
4 may be a spherical valve 10 'to which an automatic centering function is added as shown in FIG. The other end of the valve 10 is connected to a sliding rod 11a of an actuator 11 outside the pump case 1. The actuator 11 is controlled by a control circuit 12 composed of a microcomputer, and the control circuit 12 is provided in an engine 13. A signal from the rotation speed sensor is input, and when the rotation speed is low according to the rotation speed, the actuator 11 is activated to close the valve 10.

However, the actuator can be composed of a solenoid, a hydraulic cylinder, an electric cylinder, an air cylinder or the like. In the case of the hydraulic cylinder, a control circuit is not used, and when the pressure oil from the hydraulic pump becomes high, the actuator moves. It is also possible to reduce the moving rod, and in the case of an air cylinder, by introducing the air pressure (air from the supercharger) into the cylinder, it should be reduced when the rotation speed increases. Is also possible.

As shown in FIG. 2, the barrel 14 has ports A and B opened on the upper side surface thereof, and the port B is opened at a position higher than the port A, and the port A is closed to the valve 10. Port A for operation,
Port B is for starting. However, the hole of the port A may be the same as the hole diameter of the port B.

The plunger 15 is constructed so as to rotate in conjunction with the governor.
As shown in FIG. 3, the structure of No. 5 is such that a communicating groove 15a is formed in the middle of the plunger 15 as in the conventional case, and the upper end of the plunger 15 is stepped so that the engine 13 can be operated from the start to the operation. Within the range in which the jar 15 rotates, the side surface 15b of the plunger 15 in which the port B is located is configured to be high, and the side surface 15c of the plunger 15 in which the port A is located is configured to be low. The communication groove 15a is formed obliquely so that the timing of the end of the pressure feeding of the fuel can be adjusted.

With such a configuration, when the engine 13 is started, the rotational speed is low, so that the actuator 11 is operated by the control circuit 12 (it is also possible to operate the actuator 11 when the rotational speed becomes high). Is closed and fuel is supplied only from pump B. Then, the fuel is compressed when the plunger 15 rises, but the side surface 15b is located at a high position, so that the side surface 15b is quickly closed and the injection timing is advanced. That is, although the injection timing was delayed to reduce NOx, the injection timing is advanced at the time of starting to facilitate combustion. And when the engine starts and reaches the set speed,
The actuator 11 is turned off by the control circuit 12, the valve 10 is opened, fuel is supplied from the port A and the port B, and the opening area of the port A is larger than the port B. Therefore, in normal operation, the fuel injection timing is relative. The NOx can be reduced with a delay.

FIG. 8 shows the engine rotation and ON / OFF of the actuator when the control method is performed by the engine rotation.
It is a figure showing the timing of. FIG. 9 is a diagram showing the engine rotation and the operation timing of the hydraulic cylinder when the control method is performed by the hydraulic system. FIG. 10 is a diagram showing engine rotation and actuator actuation timing when the control method is air start.

[0014]

With the above-described structure, the present invention has the following effects. That is, the injection timing can be adjusted with a simple configuration, and the injection timing can be adjusted by simply processing a conventional fuel injection pump without changing the structure of the engine. I was able to keep it low.

[Brief description of drawings]

FIG. 1 is a partial cross-sectional view of a fuel injection pump.

FIG. 2 is a perspective view of a barrel.

FIG. 3 is a development view of a plunger.

FIG. 4 is a cross-sectional view showing another embodiment of the valve shown in FIG.

FIG. 5 is a partial cross-sectional view of a conventional fuel injection pump.

FIG. 6 is a development view of a conventional plunger.

FIG. 7 is a diagram showing fuel injection timings in the related art and after improvement.

FIG. 8 is a diagram showing engine rotation and ON / OFF timing of an actuator when the control method is performed by engine rotation.

FIG. 9 is a diagram showing engine rotation and operation timing of a hydraulic cylinder when the control method is performed by a hydraulic system.

FIG. 10 is a diagram showing engine rotation and actuator operation timing when the control method is air start.

[Explanation of symbols]

 1 Pump case 10 Valve 11 Actuator 14 Barrel 15 Plunger

Claims (1)

[Claims] 1. In a fuel injection pump, two ports for operation and for starting are opened in a barrel, a valve is provided in the port for operation, the valve is connected to an actuator, and the actuator is started. A fuel injection device for an internal combustion engine, wherein the fuel injection device is configured to operate only during operation and close a port for operation.