JPH01224452A - High pressure fuel injection device of engine - Google Patents

Abstract

PURPOSE:To have quick and sure closing action of a valve element by arranging the valve element in a compartment so that the valve mouth can be opened and closed from the compartment side, allowing the stem of the valve element to penetrate the valve mouth, holding it in the core of an electric magnet, and equipping the valve stem with a member to be attracted by the electric magnet. 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. A pressure accumulator chamber 7 and a small chamber 17 are formed at a body 6, and an injection valve element 13 of is arranged with possibility of advancing/retracting in the axial direction so as to be facing these chambers 7, 17 with its front and rear. In this small chamber 17, a valve element 38 is installed to open and close a valve mouth 28 from the small chamber side. The stem of this valve element 38 penetrates the valve mouth 28 and extends to the electric magnet 9 side to be held in the shaft hole of core 33 with possibility of advancing and retracting. That portion of the stem which protrudes from the shaft hole is equipped with a permanent magnet 39 to be interposed between the core 33 and a magnet disc 40.

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 is disposed outside the valve port, and is always urged to close the valve port by the elastic ↑θ force of a spring.

[Problem to be solved by the invention]

However, in such a structure, the pressure of the fuel acts in the direction of opening the valve body, so the spring will respond accordingly!
8 Ka must also be made larger.

Therefore, when the valve body is returned from the state where it is attracted to the electromagnet by the elastic 1θ force of the spring, a behavior occurs in which the valve body collides with the valve port and at the same time rebounds and bounces. As a result, the closed valve port is reopened, resulting in an unstable fuel injection amount. 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 stabilize the amount of fuel injection.

[Means to solve the problem]

The high-pressure fuel injection device according to the present invention has the valve body facing into the small chamber so as to open and close the valve port from the small chamber side, and the valve stem of the valve body is inserted through the valve port so that it can freely move forward and backward into the electromagnet core. The valve stem is provided with an adsorption member that is magnetically attracted to an electromagnet.

[Effect]

In the present invention, the fuel in the small chamber acts in the direction of closing the valve element, and the valve element is closed using the pressure of the fuel in the small chamber.

〔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 l, 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/cab) 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 rear section 10 that covers the rear of the box 8 and the outside of the electromagnet 9, and is attached to the engine main 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 rear section 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 opens into the fuel supply port 3 and axially passes through the peripheral wall of the rear section 10; 22 is a horizontal fuel passage that radially passes between the shaft hole 14 of the inner cover member 120 and the outer peripheral surface; be. These fuel passages 21 and 22 communicate with each other through a communication passage 23. Lateral fuel passage 22
is communicated with the small chamber 17 via the orifice 24, and is also communicated with the pressure accumulation chamber 7 via an orifice of a brass orifice member 27 screwed onto the front surface of the inner lid member 12. 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. Reference numeral 28 denotes a valve port which communicates the inside of the small chamber 17 and the rear section 10 and releases the pressure inside the small chamber F into the rear section IO, 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 press-fitted into 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 33 which is stacked on the rear surface of the inner cover member 12 via a spacer 31 and has a shaft hole in the center, and a magnetic disc 40 which is laminated on this core 33 via a collar 34 made of a non-magnetic material. , an electromagnetic coil 35 having a bobbin fitted into the core 33, and a bottomed cylindrical holder 36 which is fitted over the electromagnetic coil and the core from behind.

Then, the electromagnet 9 connects the front end of the holder 36 to the inner lid member 12.
The inner member is sandwiched between the fixing screw 37 screwed into the bottom of the holder 36 and the inner cover member 12, so that the inner member is disposed to face the valve port 28. Although not shown in the drawings, members such as the core 33 and the holder 36 are provided with communication passages that communicate between the fuel return port 29 and the valve port 28.

38 is a valve body that opens and closes the valve port 28. This valve body 3
8 faces into the small chamber 17 and opens and closes the valve port 28 from the small chamber 17 side, and is formed in a substantially semicircular vertical section with the diameter increasing toward the front end, and a compression coil spring 39 is used to constantly close the valve port 28. is energized by The valve stem of the valve body 38 passes through the valve port 28 and extends toward the electromagnet 9 side, and the core 3
It is held in the shaft hole of No. 3 so that it can move forward and backward. 39 is core 3
3 and the magnetic disk 40, and is provided at a portion that protrudes rearward from the shaft hole of the valve stem. This permanent magnet 39 is attached to the valve body 38 rather than the collar 34.
It is formed thinner by the amount of lift. The permanent magnet 39 is magnetically attracted to the magnetic disc 40 when the valve body 38 closes the valve port 28, and is magnetically attracted to the core 33 when the valve port 28 is opened. Note that if an extremely thin elastic film made of nylon or the like is attached to the surfaces of the core 33 and the magnetic disk 40 that face the permanent magnets 39, the collision of the permanent magnets 39 with the above member can be buffered.

41 is an external connection terminal member for connecting the electromagnetic coil 35a of the electromagnet 9 to an external power source. This terminal member 41
is formed in the shape of a screw shaft and is fixed by a collar 41a and a nut 42 so as to pass through the rear wall of the rear section 10, and a terminal 43 is sandwiched between nano) 42 and 4.2 stacked in the axial direction. ing. 44 is a sealing material that seals between the terminal member 41 and the rear section 10.

In the high-pressure fuel injection system for an engine configured as described above, when no voltage is applied to the electromagnet 9, the permanent magnet 39 is magnetically attracted to the magnetic disk 40, and the pressure inside the pressure accumulator 7 and the small chamber 17 is Since the pressures are balanced, the fuel injection port 2 remains closed. On the other hand, when a voltage is applied to the electromagnet 9, the permanent magnet 39 is attracted to the core 33, so the valve body 38 retreats from the valve port 28 to the inside of the small chamber 17, and the pressure inside the small chamber 17 is rapidly 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. When the voltage applied to the electromagnet 9 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.

When the valve body 38 is closed, the pressure of the fuel flowing into the small chamber 17 can be applied to the front end surface of the valve body 38. As a result, the valve body 38 can be quickly actuated using the pressure of the fuel, and the time required to close the valve port 28 can be shortened as much as possible.

Moreover, it is possible to prevent the valve element 38 from rebounding and bouncing as soon as it is seated on the valve port 28 due to the pressure of the fuel in the small chamber 17.

FIG. 2 is a cross-sectional view showing another embodiment, and in this figure, members that are the same or equivalent to those shown in FIG. In this embodiment, an armature 51 is used as an attraction member that is magnetically attracted to an electromagnet.
It uses

That is, the electromagnet 52 includes a core 53 that holds the valve stem and is screwed onto the inner cover member 12, an electromagnetic coil 54 that is fitted into the core 53, and a cylindrical coil that covers these members and is screwed onto the core 53. A screw cap 56 is screwed onto the rear end of the yoke 55, and the armature 51 comes into contact with the screw cap 56. The yoke 55 has an armature adsorption part 55a protruding in the inner diameter direction, and an annular ring is formed on the outer and inner peripheral surfaces near the armature adsorption part 55a to reduce the cross-sectional area of the yoke 55 and prevent magnetic flux from leaking to the outside. Groove 57.58
is provided. In this embodiment, although not shown, a communication path that communicates between the fuel return port 29 and the valve port 28 is provided in members such as the core 53 and the yoke 55.

Therefore, when a voltage is applied to the electromagnet 52, the armature 51 is attracted to the electromagnet 52 and the valve port 28 is opened, and when the voltage is removed, the valve body 38 is closed using the pressure of the fuel in the small chamber 17. .

〔Effect of the invention〕

As explained above, according to the present invention, the valve body is made to face the small chamber so as to open and close the valve port from the small chamber side, and the valve stem of this valve body can be freely advanced and retreated into the electromagnet core by passing through the valve port. Since the valve stem is provided with an adsorption member that is magnetically adsorbed by an electromagnet, the valve body can be closed using the pressure of the fuel in the small chamber.

Therefore, the valve body closes quickly and does not bounce when seated, making it possible to stabilize the fuel injection amount.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal cross-sectional view showing a high-pressure fuel injection device for an engine according to the present invention, and FIG. 2 is a longitudinal cross-sectional view of a high-pressure fuel injection device showing another embodiment. 7...Accumulation chamber, 9...Electromagnet, 17...Small chamber, 28...Valve port, 38...Valve body, 39...
・Permanent magnet, 51... Armature, 52...
electromagnet. 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, the valve body is arranged to face the small chamber so as to open and close the valve port from the small chamber side, and the valve body is opened and closed from the small chamber side. A high-pressure fuel injection device for an engine, in which a valve stem of a valve body is passed through a valve port and held movably in an electromagnetic core, and an adsorption member that is magnetically attracted to the electromagnet is provided on the valve stem.