JPH01224453A - High pressure fuel injection device of engine - Google Patents

Abstract

PURPOSE:To suppress protrusion of a component out in the radial direction by holding a stem of a valve element, which is interposed between an electric magnet and a valve mouth, in the core of electric magnet, installing a spring, which presses the valve element toward the valve mouth, at the core, and by equipping the electric magnet with a screw to adjust the resilient force of this spring. CONSTITUTION:In a device body 1, fuel in a tank 5 is pressurized by a pump 4 and sent by pressure to a supply hole 3, and then is injected from a jet 2. An injection valve element 13 is held within the body 6 so as to be facing a pressure accumulator chamber 7 and a small chamber 17 with its front and rear. A valve element 35 having an armature 36 is interposed between an electric magnet 9 and a valve mouth 28. The stem of this valve element 35 is held in the core 31 of electric magnet 9 with possibility of advancing and retracting. A compression coil spring 45 to press the valve element 35 toward the valve mouth 28 is installed on the side of core 31 opposite to the armature 36. The electric magnet 9 is fitted with a screw 48 for adjustment of the resilient force of this coil spring 45.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a high-pressure fuel injection device for an engine used, for example, in a high-speed diesel engine.

[Conventional technology]

In recent years, in diesel engines, technology for electrically controlling fuel injection has been attracting widespread attention due to demands for lower fuel consumption in the -layer and purification of exhaust gas. A fuel injection device employing this type of technology is disclosed in, for example, Japanese Patent Laid-Open No. 62-282164 (title of invention: injector). This is a so-called balanced type in which fuel pressure is applied before and after the injection valve body that opens and closes the fuel injection port.While the fuel injection port is closed by the fuel pressure, the valve body is operated by an electromagnet during fuel injection. The fuel injection valve is configured to inject fuel by opening a valve port that releases pressure on the back side of the injection valve body and retracting the injection valve body. The valve body extends in the radial direction of the body, and is constantly biased in the direction of closing the valve port by a rod-shaped spring with one end passing through the valve stem of the valve body and the other end protruding outside the body. An adjusting member for adjusting the elastic force of this spring is provided on the side.

[Problem to be solved by the invention]

However, with this structure, there is a problem that the adjustment member provided on the side of the body increases the size of the entire device. On the other hand, since the fuel injection device needs to be installed in a narrow space formed between the intake and exhaust valves and the valve train that drives these, it is preferable that the fuel injection device be as small as possible.

The present invention has been made in view of the above circumstances, and it is an object of the present invention to provide a high-pressure fuel injection device for an engine that can be miniaturized.

[Means to solve the problem]

The high-pressure fuel injection device according to the present invention includes a valve body having an armature interposed between the electromagnet provided opposite the valve port and the valve port, and the valve stem of the valve body is held movably back and forth within the electromagnet core. At the same time, a compression spring is provided on the opposite side of the core to press the valve body toward the valve port, and an adjustment screw for adjusting the elastic force of the compression spring is screwed onto the electromagnet.

[Operation] In the present invention, the elastic force of the compression spring is adjusted by the adjustment screw arranged in the axial direction of the compression spring.

〔Example〕

Hereinafter, one embodiment of the present invention will be described in detail with reference to the drawings. FIG. 1 is a longitudinal cross-sectional view showing a high-pressure fuel injection device for an engine according to the present invention, and in the same figure, the fuel injection device, which is designated as a whole by reference numeral 1, is formed into a substantially cylindrical shape as a whole. A fuel injection port 2 is opened at the front end of this fuel injection device 1, and a fuel supply port 3 is opened rearward along the axial direction at the rear end. This fuel supply port 3 is connected to high pressure (
For example, fuel pressurized to about 500 kg/aJ) is pumped from the fuel tank 5.

Reference numeral 6 denotes a body, which has a generally cylindrical shape with a small diameter at the front and a large diameter at the rear, and a hollow front box 8 having a pressure accumulation chamber 7 inside, and a female screw provided at the rear opening of this front box 8. It consists of a transfer 10 that covers the rear of the box 8 and the outside of the electromagnet 9, and is attached to the engine body (not shown) using a male screw 11 provided on the outer peripheral surface of the front box 8. A disc-shaped inner lid member 12 that defines the inside of the body 6 from front to back is held between the front box 8 and the transfer 10. In the center of the inner lid member 12 is a shaft hole 14 that holds the rear part of the injection valve body 13 that opens and closes the fuel injection port 2.
is provided. The rear part of the injection valve body 13 is formed to have a larger diameter than the front part. On the other hand, the front part of the injection valve body 13 is held by having the front end part 13a inserted into the nozzle tip 15 screwed onto the front end of the front box 8. A shim 16 is interposed between the nozzle tip 15 and the front box 8 to adjust the lift amount of the injection valve body 13. 17 is a small chamber formed by the bottom of the shaft hole 14 and the rear end surface of the injection valve body 13 and having an extremely small volume. That is, the injection valve body 13 is housed in the body 6 and is held movable in the axial direction so that the front part faces the pressure accumulation chamber 7 and the rear part faces the small chamber 17. A flange portion 13b is protruded approximately at the center, and an injection valve body 13 is provided between the spring receiver 18, which is locked by the flange portion 13b, and the front surface of the inner lid member 12. A compression coil spring 19 is elastically loaded to bias the mouth 2 in the direction of closing.

The fuel supply port 3 is arranged near the outer periphery of the front box 8, which is offset from the center. 21 is a vertical fuel passage that is opened in the fuel supply port 3 and passes through the peripheral wall of the transfer 10 in the axial direction, and 22 is a horizontal fuel passage that passes radially between the shaft hole 14 of the inner cover member 12 and the outer circumferential surface. be. These fuel passages 21 and 22 communicate with each other through a communication passage 23. Lateral fuel passage 22
communicates with a central chamber 25 provided at the rear of the injection valve body 13 via a communication hole 24 . The central chamber 25 is arranged on the axis of the injection valve body 13 and communicates with the small chamber 17 through an orifice of a first orifice member 26 made of brass and press-fitted into the rear end of the injection valve body 13 . A second orifice member 27 is made of brass and is screwed onto the front surface of the inner lid member 12, and is connected to the horizontal fuel passage 22 and the pressure accumulation chamber 7 through the orifice.
It communicates with Therefore, the pressurized fuel supplied to the fuel supply port 3 is introduced into the pressure accumulation chamber 7 and the small chamber 17 via these fuel passages and orifices. 28
11 is a valve port which communicates the inside of the small chamber 17 and the inside of the rear section 10 and releases the pressure inside the small chamber 17 into the inside of the rear section 10, and is arranged on the axis of the inner lid member 12. The inside of the rear section 10 is communicated with the outside through a fuel return port 29. The fuel return port 29 is a tube fixed to the rear end of the rear section 10 and is formed to open rearward along the axial direction, and is connected to the fuel tank 5.

The electromagnet 9 includes a core 31 having a shaft hole in the center, an electromagnetic coil 32 wound around the core 31, and a cylindrical coil fitted so as to cover the outside of the electromagnetic coil 32 and the core 31. The yoke 33 has a cylindrical shape as a whole.

35 is a valve body interposed between the electromagnet 9 and the valve port 28 to open and close the valve port 28. As shown in FIG. 2, the valve body 35 is
The valve stem extends toward the electromagnet 9, is inserted into the shaft hole of the core 31, and is held so as to be movable forward and backward. Further, a disk-shaped armature 36 is caulked and fixed to the outer peripheral portion of the valve body 35, facing the core and the yoke 31,33. That is, the armature 36 has a concave portion 37 into which the valve body 35 is fitted with its front end protruding, and is fixed to the valve body 35 by plastically deforming the opening edge of the concave portion 37 in the inner diameter direction. be done.

The yoke 33 is integrally formed with a small diameter coil covering portion 33a that covers the outside of the electromagnetic coil 32 and a large diameter fixed portion 33b that is screwed into the inner lid member 12.
The front end surface of b is in contact with the inner lid member 12 via a shim 41. Then, the coil covering portion 33a and the fixed portion 33
The intermediate part between the armature and the armature suction part 3 protrudes inward so that the diameter becomes smaller toward the front.
3C is formed. Reference numerals 42 and 43 denote an outer annular groove and an inner annular groove provided between a portion extending from the armature suction portion 33c to the coil covering portion 33a and the fixed portion 33b which is an outer portion thereof. Specifically, the outer annular groove 42 is provided between the coil covering portion 33a and the fixed portion 33b, and the inner annular groove 43 is provided between the armature adsorption portion 33.
c and the fixed part 33b, and the yoke 3
The cross-sectional area of the portion from the armature suction portion 33c and the coil covering portion 33a of No. 3 to the fixed portion 33b is reduced. Although not shown, a communication hole is provided in the yoke 33 and other members so that the fuel return port 29 and the valve port 28 communicate with each other.

Reference numeral 45 denotes a compression coil spring that constantly presses the valve body 35 toward the valve port 28 and compresses and deforms itself in the axial direction. This spring 45 is loaded into a recess 46 provided on the axis of the core 31 on the side opposite to the armature. 47 is a spring receiver provided at the rear end of the valve body 35;
Reference numeral 8 denotes an adjustment screw that is screwed into the opening edge of the concave portion 46 from the rear and adjusts the elastic force of the spring 45 depending on the amount of screwing.

51 is an external connection terminal member for connecting the electromagnetic coil 32 of the electromagnet 9 to an external power source. This terminal member 5I is formed in the shape of a screw shaft, and is fixed by a collar portion 51a and a nut 52 so as to pass through the rear wall of the rear section 10, and the terminal 53 is sandwiched between the nuts 52 and 52 stacked in the axial direction. has been done. 54 is a sealing material that seals between the terminal member 51 and the rear section 10.

In the high-pressure fuel injection device for an engine configured in this way, when no voltage is applied to the electromagnet 9, the pressures in the pressure accumulation chamber 7 and the small chamber 17 are balanced, so the fuel injection port 2 is in a closed state. is maintained. On the other hand, electromagnet 9
When a voltage is applied to , a magnetic flux is generated around the electromagnetic coil 32 that detours to the armature 36 , so the valve body 35 retreats from the valve port 28 against the elastic force of the compression coil spring 45 , and the small chamber 17 The pressure inside is suddenly reduced. As a result, the injection valve body 13 is retracted by the pressure of the fuel in the pressure accumulation chamber 7, the fuel injection port 2 is opened, and fuel is injected. Then, when the voltage application is removed, the pressure in the small chamber 17 with a small volume increases momentarily and presses the injection valve body 13, so that the fuel injection port 2 is closed.

Further, the elastic force of the spring 45 can be adjusted by changing the screwing amount of the adjusting screw 48 arranged in the axial direction of the spring 45. Therefore, since the spring 45 and the adjustment screw 48 can be prevented from protruding in the outer radial direction beyond the electromagnet 9, the diameter of the portion where the spring 45 and the adjustment screw 48 are attached can be made small.

Adjustment of the elastic force t8 of the spring 45 can be performed with the electromagnet 9 alone or with the electromagnet 9 screwed onto the inner lid member 12. For example, the elastic force does not change due to assembly.

FIG. 3 is a sectional view of a main part showing another embodiment, and in this figure, the same or equivalent members as shown in FIG.

Reference numeral 61 denotes a bell spring as a compression spring, and a plurality of bell springs 61 are stacked facing each other in the axial direction. Therefore, also in this embodiment, the elastic force of the plate spring 61 can be adjusted by changing the screwing amount of the adjusting screw 48.

〔Effect of the invention〕

As explained above, according to the present invention, a valve body having an armature is interposed between the electromagnet provided opposite to the valve port and the valve port, so that the valve stem of the valve body can freely move forward and backward into the electromagnet core. A compression spring is provided on the opposite armature side of the core to press the valve body toward the valve port, and the elasticity t8 of this compression spring is
Since the adjustment screw for adjusting the force is screwed onto the electromagnet, the elastic force of the compression spring can be adjusted using the adjustment screw arranged in the axial direction of the compression spring.

Therefore, the compression spring and the adjustment screw are prevented from protruding further in the outer radial direction than the electromagnet, and the diameter of the portion to which these members are attached can be reduced, so that the entire device can be made smaller.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal sectional view showing a high-pressure fuel injection device for an engine according to the present invention, FIG. 2 is a sectional view showing a valve body, and FIG. 3 is a sectional view of main parts showing another embodiment. 7...Accumulation chamber, 9...Electromagnet, 17...Small chamber, 28...Valve port, 33...Yoke, 35...
...Valve body, 45..., Compression coil spring, 48...
Adjustment screw. Patent applicant Yamaha Motor Co., Ltd.

Claims (1)

[Claims] A body having a pressure accumulation chamber and a small chamber into which pressurized fuel is introduced, and an injection valve body held within the body so that its front part faces the pressure accumulation chamber and its rear part faces the small chamber, and opens and closes a fuel injection port. In a high-pressure fuel injection device equipped with a valve body operated by an electromagnet that opens and closes a valve port for releasing pressure in the small chamber, a valve body having an armature is interposed between the electromagnet and the valve port, and the valve body is operated by an electromagnet. The valve stem is held in the electromagnetic core so that it can move forward and backward, and a compression spring is provided on the opposite side of the core to press the valve body toward the valve port, and an adjustment screw that adjusts the elastic force of this compression spring is attached to the electromagnet. The engine's high-pressure fuel injection system is screwed onto the engine.