JPS61126367A - Fuel injection device - Google Patents

Abstract

PURPOSE:To prevent the generation of secondary injection and cavitation and complete injection with a fuel valve being left as in a high pressure while improve the sharpness of its injecting action, by providing a piston, which controls the injection timing by pressing a needle valve by the hydraulic pressure of oil, in an upper part of the fuel valve while solenoid operated valves controlling supply of the hydraulic pressure oil to the piston. CONSTITUTION:A fuel valve 101 provides in its upper part a piston 115 pressing a needle valve 107 by the hydraulic pressure of oil. The hydraulic pressure oil, controlling the piston 115, is supplied from an discharged to an oil hydraulic power supply 310, separately provided from the injection system, through two solenoid operated valves 303, 304. The both solenoid operated valves 303, 304 are controlled by a trigger signal from a microcomputer in the timing set in accordance with the speed of an engine and the rack position of a fuel pump 01. The fuel pump 01 provides a check valve 08 and a check valve 11 equipping an orifice 14. In this way, the fuel valve, completing injection being left as holding a high pressure, enables poor atomization of fine particles to be eliminated.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a fuel injection device for a diesel engine.

[Conventional technology]

FIG. 3 shows a conventional fuel injection device for a diesel engine.

In the figure, 01 is the fuel 2 knob body.

02 is plunger barrel, 03 is plunger barrel.

04 is the silanger lead, 05 is the oil supply and drain hole, 06 is the oil supply chamber, 07'' is the discharge valve seat, and 08' is the discharge valve.

09' is a discharge valve suction back collar, and 10' is a discharge valve spring.

11'' is a discharge valve presser, and 12'' is a control rack. Further, 101 is a fuel valve body, 102 is a nozzle tip, and 103 is a cap nut, which tightens the nozzle tip f102 to the fuel valve body 101.

104 is an oil passage in the fuel valve, 105 is an oil passage in the nozzle tip,
106 is an oil reservoir. 107 is a needle valve.

108 is a nozzle hole, 109 is a needle valve push rod, 110 is a spring holder, 1
11 is a spring, and 112 is a needle valve opening pressure adjustment screw. 2
01 is a high pressure injection pipe that connects the fuel pump and the fuel valve.

It also enters the upper part of Granger 03 from oil hole 05. Next, to explain the operation of the pump, the Granger 03
rises and closes the oil supply/discharge hole 05, compression of the fuel begins, and the high-pressure fuel pushes up the discharge valve 08', causing the injection pipe 201. Fuel valve oil passage 104. Nozzle chip internal oil passage 10
5 and is led to the oil sump section 106. Here needle valve 10
When oil pressure acts on 7 and becomes greater than the force held down by the spring 111, the needle valve 107 opens.

Fuel is injected from the injection hole 108 into a cylinder of an engine (not shown). When the grand gloss 03 further rises, the plansha lead 04 is applied to the oil supply/discharge hole 05, and the high-pressure upper part of the plansha is communicated with the low-pressure oil supply chamber 06, so that the pressure decreases and discharge ends.

As a result, the pressure within the system gradually decreases, and the pressure in the oil sump 106 also decreases, and the spring force overcomes the hydraulic pressure, closing the needle valve and ending the injection. Normally, the pressure at the injection path is about 4% higher than the pressure at the beginning of injection.
This is relatively low. Also.

When the pressure on the discharge path decreases, the discharge valve 08 closes immediately, and at this time, a long closed pipeline is formed between the fuel valve and the pump via the injection pipe 201, so the pressure waves continue to reciprocate during this time. This pressure wave causes the needle valve 107 to restart, causing re-injection from the nozzle hole.

Cavities may be created in the pipes or in the oil reservoir. This re-injection phenomenon is usually called secondary injection.

Figure 4 shows the injection pressure and movement of the needle valve.

[Problem that the invention seeks to solve]

The above has the following drawbacks.

As mentioned above, the pressure in the injection path is lower than the injection start pressure. This results in a coarse spray being injected into the cylinder where combustion has already started and air has been consumed, leading to poor combustion and the generation of smoke, which is not good for the engine. Furthermore, since the secondary injection is also a low-pressure injection and a late injection, the phenomenon is even worse than the above-mentioned one. If the occurrence of cavities becomes large enough, it may lead to cavitation erosion and damage to injection pipes, needle valves, etc. Also.

This may lead to deterioration of the seal part or seizure of the needle valve sliding part.

[Means to resolve the issue]

The object of the present invention is to focus on the above-mentioned points, to eliminate secondary injection and cavity generation, and to simultaneously complete injection at high pressure.

The purpose of the present invention is to provide a fuel injection device that can improve what is commonly called ``cutting of injection.'' Its feature is that it is installed at the top of the fuel valve and uses hydraulic pressure to press a needle valve to control the end of injection. Surugestone.

A microcomputer that sets and stores the timing of the hydraulic pressure according to the engine rotation speed and pump rack position and issues a trigger signal at the set timing; is controlled by the above trigger signal.

Two electromagnetic valves are provided in the fuel pump, a check valve that operates at the time of discharge and a check valve that operates at the end of discharge and is provided with a throttle.

[For production]

In this case, by being able to complete the injection with high pressure in the latter half of the injection and by absorbing the pressure on the pump side,
There are no problems with secondary injection or cavitation.

〔Example〕

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is an explanatory diagram showing a fuel injection device according to the present invention.

In the figure, 01 is the fuel cylinder body, 02 is the plunger barrel, 03 is the plunger, 04 is the plunger lead,
05 is the oil supply and drain hole, and 0 and 6 are the oil supply chambers.

07 is the valve seat, 08 is the ball valve or check valve, 09 is the spring,
10 is a spring receiver provided with an oil passage.

11 is a ball valve or check valve; 12 is a spring; 13 is a spring receiver with an oil passage; 14 is an orifice.

15 is a presser foot, and 16 is a control rank.

101 is a fuel valve body, and 102 is a nozzle tip.

A cap nut 103 fastens the nozzle tip 102 to the ffi valve body 101. 104 is an oil passage in the fuel valve;
105 is an oil passage in the nozzle chip, and 106 is an oil reservoir. 107 is a needle valve, 1o8 is a nozzle hole.

109 is a needle valve push rod, 11o is a spring holder, 111 is a spring,
112 is a needle valve opening pressure adjustment screw, and 113 is a lock nut. 114 is a piston, and 115 is a piston.

116 is a piston push rod, 117 is a spring, and 118 is a piston upper metal fitting.

201 is a high pressure injection pipe that connects the fuel pump and the fuel valve.

301 is a hydraulic pipe, and 3o2 is a solenoid valve mounting hardware.

303 is a solenoid valve (Normal C1ose),
304 is a solenoid valve (Normal 0pen), 3
05 is a relief pipe, 306° and 307 are hydraulic pipes, 3o8 is a pressure reservoir, 3o9 is a pump, and 31o is an oil tank.

401 is a rack position detector (e.g. potentiometer)
, 402 is a trigger signal generator, and 4o3 is a rotation/4' pulse generator.

The operation in the case of the above configuration will be described.

First, I will explain how the microcomputer works.

In the computer, as a memory part, information on the crank rotation angle at which the trigger signal should be issued is input in advance with respect to the engine speed NE and the pump rack Rc.

When the 2nd engine rotational speed, the rack position signal, and the trigger signal are input, the 1st engine rotational speed is calculated, the rack position is determined, the input trigger signal and the required trigger timing are calculated, and the trigger signal is Emitted.

Next, regarding the newly installed hydraulic system, the oil in the tank 310 is brought to high pressure by the bomb F309, and is maintained at a constant pressure by the action of the pressure accumulator 308. The electromagnetic valve mounting hardware 302 has an oil passage formed therein, and electromagnetic valves 303 and 304 are attached thereto. Solenoid valve 303 is Normal C1ose Type
Normally closed with e, solenoid valve ) 304 is Norm
al 0pen Type and is normally open.

Hydraulic pipe 301 and relief pipe 305 open to the tank.

The operating times of the solenoid valves 303 and 304 are set by a solenoid valve controller, and are driven by a trigger signal from a microcomputer.

The operation of the injection system will be described.

The oil supply chamber 06 in the fuel pump 01 is filled with fuel by a fuel supply pump (not shown), and the oil supply and discharge hole 0
It also enters the upper part of plunger 03 from 5. When the plunger 03 is raised by a cam rotating in synchronization with the crankshaft of the engine (not shown) and the oil supply/drain hole 05 is closed, fuel compression begins. The high-pressure fuel is pushed up to the injection pipe 201° and the oil passage 104 in the fuel valve. The oil is guided to an oil reservoir 106 through an oil passage 105 within the nozzle tip. Here, oil pressure acts on the needle valve 107, and when the oil pressure becomes greater than the force held down by the spring 111, the needle valve 107 opens and fuel is injected into the cylinder of the engine (not shown) through the injection hole 108.

Silan gloss 03 further increases, Plant gloss lead 04
When the oil is applied to the oil supply/discharge hole 05, the high pressure upper part of the plunger communicates with the low pressure oil supply chamber 06, so the pressure decreases and the discharge ends.

This also reduces the pressure within the sequential system. At this time, the aforementioned hydraulic system and electromagnetic valve have already been activated, and hydraulic pressure is applied to the upper part of the piston 115 through the hydraulic pipe 301. Since the piston 115 is larger than the needle valve 107 and has a diameter several times that of the needle valve 107, an oil sump! Balanced at less than a tenth of the pressure of +106. When the oil pressure at the top of the piston becomes higher than this, the piston descends and the piston push rod 116. Spring receiver 110. The needle valve 107 is also lowered via the push rod 109 i) I! Complete the ij shot. At this time, although the pressure in the oil sump portion 106 is high, the needle valve is lowered and the nozzle hole is closed, so the pressure further increases and propagates to the pump side. But on the pump side, through the orifice? - Press the valve 11 open and decelerate appropriately to lower the pressure. Therefore, pressure propagation at high pressure to the nozzle side is eliminated. When high pressure no longer acts on the oil sump 106, the solenoid valve is deactivated and the piston 115
The pressure at the top decreases. The piston is returned by spring 117. At this time, the pressure in the oil reservoir 106 has dropped sufficiently and the needle valve 107 is closed by the spring 111.

In this way, the injection can be completed at a high pressure in the latter half of the injection.

FIG. 2 shows the injection phenomenon according to the present invention.

You can see that oil pressure acts on the piston in the latter half of injection, and injection is complete even though the pressure on the nozzle side is still quite high. It can be seen that even though the pressure on the pump side is high due to the valve closing, the pressure is absorbed on the pump side.

〔Effect of the invention〕

The above case has the following effects.

As mentioned above, injection can be completed to a high pressure of 1 in the latter stage of injection, and there is no problem of secondary injection or cavitation because the pressure is absorbed on the pump side.

(1) The sloppy injection at low pressure in the latter half of injection is eliminated, and (2) poor atomization of the spray is eliminated and injection is completed quickly, ensuring good combustion in the engine and leading to improved performance.

(2) It is possible to provide a highly reliable engine injection system since the occurrence of secondary injection that adversely affects engine performance or cavitation that causes a decrease in durability is eliminated.

[BRIEF DESCRIPTION OF THE DRAWINGS] Fig. 1 is an explanatory diagram showing an embodiment of the device according to the present invention, and Fig. 2 shows the piston oil pressure, needle valve, nozzle pressure, and pump pressure of the device in Fig. 1. Line diagram. FIG. 3 is an explanatory diagram showing a conventional fuel injection device, and FIG. 4 is a diagram showing pump pressure, nozzle pressure, and needle valve pressure of the device in FIG. 3. 01...Fuel pump main body, 08,11...Check valve. 101...Fuel valve body, 107...Needle valve', 11
5... Piston, 201... Injection pipe, 303.30
4... Solenoid valve. Age 30 Large 4th figure

Claims (1)

[Claims] 1. In a diesel engine fuel injection device consisting of a jerk-type fuel pump, an injection pipe, and a fuel valve, a piston is provided at the upper part of the fuel valve and presses a needle valve with hydraulic pressure to control the end of injection, and a timing of action of the hydraulic pressure is provided. A microcomputer that sets and stores the value according to the engine rotational speed and pump rack position and issues a trigger signal at the set timing, and controls the action of the oil pressure by applying the oil pressure from a hydraulic source separate from the injection system to the trigger signal. Two solenoid valves that control
A fuel injection device characterized in that the fuel pump is provided with a check valve that operates at the time of discharge and a check valve that operates at the end of discharge and is provided with a throttle.