JPS6131657A - Fuel injection device - Google Patents

Abstract

PURPOSE:To aim at realizing a high pressure fuel injection and at facilitating the control of injection timing and fuel amount, by utilizing a low pressure type hydraulic pump providing with a distribution type or line type timer and a metering device, and a hydraulically driven injector provided with an amplifying piston in combination. CONSTITUTION:When a cam 102 driven by a cam shaft 101 which rotates in synchronism with the rotation of a crankshaft runs on a roller 103, a plunger 105 ascends to compress hydraulic oil in a cylinder 107. Then the hydraulic oil pushes up a discharge valve 108, and reaches a hydraulically driven injector 110 after passing through a conduit 109. Therefore, high pressure hydraulic coil depresses a plunger 11 provided with an amplifying device to compress fuel oil in an injector cylinder 112, which has passed through an oil feed pipe 119. As a result the fuel oil has a high pressure to push up a fuel injection valve 114, overcoming a valve spring 115, and therefore, fuel oil is injected from a jet port 116 into a combustion chamber 117 which is defined by a piston 118, etc.

Description

[Detailed description of the invention] The present invention relates to a fuel injection device for an internal combustion engine.

FIG. 1 shows a typical conventional unit injector.

In the figure, 1 is a cam, 2 is a roller, 3 is a zonal rod, 4 is a rocker arm, and 5 is a unit injector (
or pump injector).

6 is a piston, and 7 is a combustion chamber.

When the roller 2 is pushed up by the cam 1 of the camshaft rotating in synchronization with the crankshaft (not shown), the bushing rod 3. The unit injector 5 is activated via the rocker arm 4, and the internal plant gear and injector are activated to inject fuel at high pressure into the combustion chamber 7 for combustion.

Figure 2 shows the inside of the unit injector.

51 is tar <, 52 is plant, 53 is barrel,
54 is a needle valve, and 55 is a nozzle hole. The tappet 51 is driven by the rocker arm 4 and the plunger 52 is pushed down, generating high pressure in the barrel 53, pushing up the needle valve 54 and injecting fuel from the injection hole 55 into the combustion chamber 7.

As shown in Figure 2, a unit injector has a pump and a fuel valve integrated into one unit, so there is no injection pipe and fuel can be injected at high pressure.

Unlike conventional jerk-type fuel injection systems, there is no secondary injection due to the presence of an injection tube.

However, it has the following drawbacks.

First, it is difficult to control the timing of fuel injection.

Next, the fuel injection amount is controlled by rotating the push rod shown in Fig. 2 with a rack rod 56, but this requires a long rack rod to pass through the cylinder head, and the structure is complicated, and it is difficult to control the speed. The power for becomes greater. Furthermore, since a large force commensurate with the high injection pressure is directly applied to the pump drive system, there are drawbacks such as the necessity to increase the size of the camshaft.

FIG. 3 shows a conventional single plunger dispensing injection pump 0. In the figure, 11 is a camshaft, 12 is a cam, 13 is a cam roller, 14 is a timing adjustment device, 15 is a sylanger, and 16 is a fuel amount adjustment device.

17 is a cylinder barrel, 18 is a discharge valve, and 19 is an injection pipe. FIG. 4 shows a fuel injection valve 20 connected to the tip of the injection pipe 9, where 21 is a needle valve and 22 is a valve spring.

23 is a nozzle hole.

The rotation of the camshaft 11 causes the cam 12 to rotate.

When the o-ra 13 is raised, the syringer 15 is pushed up to compress the fuel in the cylinder 17, and the discharge valve 18. Fuel is sent to the fuel valve 20 via the fuel injection pipe 19. The discharge amount is controlled by moving the fuel amount adjusting device 16 up and down. Further, the injection timing is controlled by moving the position of the cam roller 13 by a timing adjustment device 14 so that the injection is performed at a predetermined timing.

The delivered fuel passes through the injection pipe 19 and is sent to the fuel valve 20, pushing up the needle valve 21 against the spring 22 and opening the injection hole 2.
From 3, it is ejected into the combustion chamber and burns.

This injection system is a system that sends fuel from a single pump to a plurality of fuel valves, and has the advantage that timing can be easily controlled and fuel injection amount can also be easily controlled.

However, it has the disadvantage that it cannot withstand high-pressure jetting because there is a lot of slippage in the contact between the cam and the roller. While the unit insoector described above is capable of high-pressure spraying of 1,000 atmospheres or more, the two-piece system has the disadvantage that it can withstand only about 700 atmospheres at most.

An object of the present invention is to provide a high-pressure fuel injection device that is easy to control injection timing and injection amount, and is characterized by a hydraulically driven injector and a timer that supplies high-pressure oil to operate the injector. And distribution type or column type hydraulic oil month with metering device? The hydraulic oil passage provided between the hydraulic oil pump and the hydraulically driven injector is formed in a hydraulic expansion piston in which the piston surface on the hydraulic oil side is thicker than the piston surface on the fuel oil side. It is equipped with a hydraulically driven injector plunger.

In this case, (1) a low-pressure pump with a distributed or in-line timer and metering device is used to control and timing the injection amount, and (2) only the injection energy is sent from the low-pressure pump. Received by the injector's widening piston,
The fuel in the injector barrel is pressurized to cylinder pressure and injected, and (3) a hydraulically driven injector with an increased width piston is combined with a conventional row type or distributed fuel phase injection pump to achieve high pressure and high controllability. It uses a fuel injection system.

A fuel injection device according to the present invention will be explained below with reference to the drawings.

FIG. 5 is an explanatory diagram showing one embodiment of the fuel injection device according to the present invention.

In the figure, 100 is a hydraulic oil pump, 101 is a camshaft,
102 is a cam, and 103 is a cam roller.

104 is a timer, 105 is a pusher, 106 is an injection energy metering device, 107 is a cylinder, 108 is a discharge valve,
109 is an energy transmission pipe, that is, a hydraulic oil path; 110 is a hydraulically driven injector; 111 is an amplifier device;
The upper part has a larger diameter.

112 is an injector cylinder, 113 is an amplification plunger return spring, 114 is a fuel injection valve, 115 is an injection valve spring, 116 is a nozzle hole, and 117 is a combustion chamber.

118 is a piston, and 119 is a fuel oil supply pipe.

FIG. 6 is a sectional view showing the injector.

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

When the cam 102 driven by the camshaft 101 that rotates in synchronization with the crankshaft is raised to the roller 103, the syringer 105 rises and compresses the hydraulic oil in the cylinder 107, and the energy of the compressed hydraulic oil is discharged. Push up the valve 108 and pass through the energy transfer pipe 109 to the hydraulically driven injector 110. The energy of the high-pressure hydraulic oil that has reached the injector 110 acts on the large piston surface of the plunger with amplifier 111 and pushes the plunger downward. Compress fuel oil. At this time,
Since the amplifying plunger 111 has a small diameter on the fuel oil side, the pressure is amplified to a higher pressure on the hydraulic oil side.

The high-pressure fuel oil moves the fuel injection valve 114 to the valve spring 115.
The fuel is pushed up against the pressure, and is injected from the injection hole 116 into the combustion chamber 117, which is made up of a piston 118 and the like. When the plunger 105 of the hydraulic oil pump 100 finishes discharging, the pressure on the hydraulic oil side of the injector plunger 111 decreases and is returned upward by the return spring 113 in preparation for the next injection.

At this time, the injection amount is adjusted by adjusting the discharge amount of the hydraulic oil pump 100 to adjust the energy to be sent out, and thereby controlling the stroke of the plunger 111 with an amplification device.

Also, the timing is determined by the timer 104 of the hydraulic oil pump 100.
done by.

The above case has the following effects.

The present invention makes it possible to perform high-pressure injection, and by easily adjusting the timing and injection amount, high-pressure fuel injection can be performed at the optimum injection timing, thereby realizing a high-performance diesel engine. Also.

It is possible to use a low pressure pump, and cost reduction is possible.

[Brief explanation of the drawing]

Fig. 1 is an explanatory diagram showing a conventional unit injector, Fig. 2 is a sectional view showing the inside of the unit injector shown in Fig. 1, Fig. 3 is a sectional view showing a conventional single plantar distributing injection pump, and Fig. 4 is a sectional view showing the inside of the unit injector shown in Fig. 1. FIG. 5 is a sectional view showing a fuel injection valve, FIG. 5 is an explanatory view showing a fuel injection device according to an embodiment of the present invention,
FIG. 6 is a cross-sectional view of the hydraulically driven injector of FIG. 5. 100...Hydraulic oil pump, 1o4 ・Timer, 106・
... Metering device, 1o9... Hydraulic oil path, 11o... Hydraulic driven in-chef l, 111... Plunger with amplifier. Force 20 7I = 3 figures

Claims (1)

[Claims] 1. A hydraulically driven injector, a distribution or line-type hydraulic oil pump with a timer and metering device that supplies high-pressure oil to operate the injector, and an actuator installed between the hydraulic oil pump and the hydraulically driven injector. A fuel injection device characterized in that the plunger of the hydraulically driven injector is formed in a hydraulically widened piston in which the piston surface on the hydraulic oil side is larger than the piston surface on the fuel oil side.