JPS61261659A - Unit injector device - Google Patents

Abstract

PURPOSE:To eliminate dependence of injection characteristics on speed and improve controllability by injecting fuel in such time sequence as lowering a plunger in line with rotation of a cam, pressurizing fuel, storing it in an accumulating part and then opening an electromagnetic valve. CONSTITUTION:A plunger 13 starts going down at point A where the oval part 151 of a rotating cam 15 begins touching a head part 14. Since a solenoid coil 19 magnetized, and A port and B port are shut off when the angle of the cam 15 reaches point B next, fuel starts to accumulate in a pressurized room, being pressed by the descending plunger 13. Consequently, a valve body 26 is pushed down under pressure of fuel, and the inclining part 211 of a nozzle needle 21 blocks a nozzle 27 so that fuel passes through a valve hole 24 and starts to be stored in the accumulating part 22. And when A port and B port communicate with each other at point C, fuel in the pressurized room 12 flows out into a drain, pushing up the valve body 26 so that the nozzle 27 is opened and fuel is injected.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a unit injector device as a fuel injection device for a diesel engine.

[Technical background of the invention and its problems] Conventionally, there is a unit injector device that injects diesel engine fuel without using an injection pipe, but in such a unit injector device, the speed dependence of the injection characteristics It is desired to eliminate this and further improve controllability.

[Object of the Invention] The present invention has been made in view of the above points, and an object of the present invention is to provide a unit injector device that has no speed dependence of injection characteristics, is capable of high-pressure injection, and has excellent controllability.

[Summary of the Invention] A pressurized chamber is provided which has an inlet connected to a fuel supply source, an outlet for discharging fuel to the drain side, and a supply port for supplying pressurized fuel, and a slider is provided in the pressurized chamber. A plunger is movably inserted, the cam is rotated so as to come into contact with the head of the plunger, and the descending process of the plunger applies pressure to the fuel stored in the pressurizing chamber, and the fuel is supplied to the supply port,
It is stored in the pressure accumulator via the check valve. The unit injector device is configured to inject the fuel stored in the pressure accumulating portion at the timing when the electromagnetic on-off valve provided on the discharge port side is opened.

[Embodiment of the Invention] A unit injector device according to an embodiment of the present invention will be described below with reference to the drawings. In FIG. 1, 11 is a main body, and 12 is a pressurizing chamber formed in this main body 11. In FIG. A plunger 13 is slidably inserted into this pressurizing chamber 12 in an airtight manner. This plunger 1
A cam 15 that rotates with the rotation of the camshaft of the engine is in contact with the head 14 of the engine.

Therefore, according to the rotation of this cam 15, the plunger 1
1 moves upward or downward within the pressurizing chamber 12.

Note that 16 is a return spring that always urges the head 14 upward.

By the way, the pressurized chamber 12 has an inlet 121 formed on the fuel supply side, an outlet 122 formed on the drain side,
A supply port 123 for supplying pressurized fuel is formed. Further, a check valve 17 is interposed between the suction port 121 and the fuel supply source, and an electromagnetic on-off valve 18 is interposed between the discharge port 122 and the drain side. This electromagnetic on-off valve 18 puts the A boat and port 8 in a non-communicating state or a communicating state depending on the energized or de-energized state of the solenoid coil 19 (in this embodiment, when the solenoid coil 19 is in the de-energized state, the A boat and B boat are in communication). Therefore, fuel is stored in the pressurizing chamber 12 only during the time when Boat A and Boat B are cut off.

By the way, the supply port 123 is connected to a nozzle section 23 consisting of a check valve 20, a nozzle needle 21, and a pressure accumulating section 22. The check valve 20 includes a nozzle portion 23 and the pressurizing chamber 1.
The valve whose valve hole 24 formed between the two is closed due to the biasing force of the spring 25! 26 are provided. This valve;
The upper end portion of the nozzle needle 21 is attached to 26, and the lower end portion of the nozzle needle 21 closes the nozzle 27 by an inclined portion 211 formed at the lower end portion as the nozzle needle 21 moves downward. It is composed of Further, 28 is a spring for restricting the upward movement of the nozzle needle 21.

Note that 29 is a combustion chamber of the diesel engine, and 30 is a piston.

Next, the operation of one embodiment of the present invention configured as described above will be explained with reference to FIG. The cam 15 rotates, and the inner part 151 of the cam 15 is the head? The plunger 13 begins to descend from point A where it begins to contact gS14. In this state, the solenoid coil 19 is in a non-energized state, so the A boat and the B boat are in communication.
It is returned to the drain via the B boat. And cam 1
As the cam 15 rotates, the plunger 13 continues to descend, and the cam 15
When the angle reaches point B, the solenoid coil 19 is energized and the A boat and the 8 boat are cut off. Therefore, fuel begins to accumulate in the pressurizing chamber 12 from point B, and this fuel is pressurized by the descending plunger 13. Therefore, the valve body 26 is pushed down by the high pressure of the fuel, and the inclined portion 211 of the nozzle needle 21 comes into contact with the nozzle 27 and closes it. Therefore, the pressurized fuel is transferred to the valve hole 2.
4 begins to accumulate in the pressure accumulating portion 22.

Then, the cam 15 further rotates, and the curved surface 15 of the cam 15
When the plunger 2 reaches the 0 point where it starts to contact the head 14, the plunger 1
3 is stopped, and the stroke of plunger 13 becomes constant. Even up to this point, pressurized fuel is stored in the pressure accumulating portion 22.

Next, the timing of injecting the fuel stored in the pressure accumulator 15 into the combustion chamber 29 will be described. This timing is the timing to stop the excitation of the solenoid coil 19 and to connect the A boat and the B port again. In other words, D
When the A boat and the B port are communicated with each other at the point, the fuel in the pressurizing chamber 12 escapes to the drain via the A boat and the B boat, so that the pressure in the pressurizing chamber 12 drops rapidly. Therefore, the valve body 26 is pushed up by the biasing force of the spring 25, and the valve hole 24 is closed by the valve body 26. By pushing up the valve body 26, the nozzle needle 21 moves upward.

Therefore, the nozzle 21 that had been blocked by the inclined portion 211 opens, and the high-pressure fuel stored in the pressure accumulating portion 22 is injected into the combustion chamber 29 via the nozzle 27.

In this way, the amount of fuel injection can be increased or decreased by advancing or delaying the timing of point B, which interrupts boat A and boat B. Then, by changing the timing D at which the A boat and the B boat are brought into communication again, the injection timing can be changed. This can be done by electronically controlling the timing of energizing and de-energizing the solenoid coil 19.

In addition, in FIG. 2, a is the section where A boat and 8 boats are communicating, b is the section where A boat and B boat are cut off, and C is a section where A boat and B boat start communicating.
d is a section where boat A and boat 8 communicate.

[Effects of the Invention] As described in detail above, according to the present invention, it is possible to provide a unit injector device that has no speed dependence of injection characteristics, is capable of pressure injection, and has excellent controllability.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view showing a unit injector device according to an embodiment of the present invention, and FIG. 2 is a characteristic diagram of cam angle versus plunger stroke. Cow 12...pressure chamber, 13 plunger, 15...cam,
18... Solenoid on-off valve, 19... Solenoid coil,
20... Check valve, 21... Nozzle needle, 22...
... Pressure accumulator, 27... Nozzle.

Claims (1)

[Claims] a pressurizing chamber having an inlet connected to a fuel supply source, an outlet for discharging fuel to the drain side, and a supply port for supplying pressurized fuel; a pressure member, a cam that rotates so as to come into contact with the head of the pressure member and causes the pressure member to reciprocate, a pressure accumulator connected to the supply port via a check valve, and the check check. A unit injector device comprising: a nozzle portion consisting of a nozzle needle interlocking with a valve; and an electromagnetic on-off valve provided on the discharge port side.