KR20010076916A - Compressible fuel injection device for diesel engine - Google Patents

Abstract

PURPOSE: A pressure accumulation type fuel injection apparatus for diesel engine is provided, in which an orifice plate is in a tight surface-contact with the armature valve body, to thereby reduce parts count and fuel leakage. CONSTITUTION: A fuel injection apparatus comprises a high pressure side fuel passage(315) for supplying high pressure fuel from an injection nozzle(321) of an injector; an injector body(322) having the high pressure side fuel passage; an electronic valve(323) for controlling pressure of a control pressure chamber(307); an orifice plate(306) interposed between the injector body and the armature valve body; and an outlet orifice(305) and an inlet orifice(304) arranged at the orifice plate, wherein the outlet orifice has an angle for limiting the flow rate of the fuel discharged from the control pressure chamber toward the low pressure side upon opening of the electronic valve, and the inlet orifice controls the high pressure fuel being introduced from the high pressure side fuel passage to the control pressure chamber.

Description

Compressible fuel injection device for diesel engine

The present invention relates to a fuel injection device for controlling the fuel injection timing by opening and closing the solenoid valve.

As shown in FIG. 2, the pressure accumulating fuel injector of the conventional diesel engine is provided with a control pressure chamber 204 on the semi-injection side of the control piston 202 accommodated in the injector, so that the control pressure chamber 204 and the low pressure side fuel passage ( It is known to control the fuel injection timing by controlling the 210 to the solenoid valve 209.

The injector body 211 is a piston guide 213 slidably supporting a reciprocating control piston 202 such as a needle valve 201 and a fuel inlet 203 at a common rail (not shown). Inlet orifice 205 and outlet orifice 206 connected to each other are laminated and fastened. A control pressure chamber 204 is formed between the piston guide 213 in which the control piston 202 slides and the inlet orifice 205. The fuel ports provided in the two orifice portions regulate the amount of fuel outflow from the control pressure chamber 204 and the amount of fuel inflow into the control pressure chamber 204. The valve portion 207 of the solenoid valve 209 is accommodated in the armature valve body 208 so as to reciprocate, and the fuel is discharged through the fuel port of the outlet orifice 206 to connect with the low pressure side fuel passage 210. do.

When closing the solenoid valve 209, the connection between the control pressure chamber 204 and the low pressure side fuel passage 210 is cut off, and the high pressure fuel supplied from the common rail (not shown) is supplied to the fuel inlet 203 and the inlet orifice 206. Is supplied to the control pressure chamber 204 through the fuel port. Therefore, the fuel injection is not performed because the needle valve 201 closes the open holes like the control piston 202 by the fuel pressure in the control pressure chamber 204.

The control pressure chamber 204 and the low pressure side fuel passage 210 are connected by the valve portion 207 to lift when the solenoid valve 209 is opened, and passes through the outlet port of the outlet orifice 206 and the control pressure chamber 204. When the high pressure fuel flows out into the low pressure side fuel passage 210 and the fuel pressure in the control pressure chamber 204 decreases, the needle valve 201 is lifted like the control piston 202 to inject fuel.

However, in the conventional fuel injector as shown in FIG. 2, since the inlet orifice 205 and the outlet orifice 206 are formed as separate parts, the number of parts and the number of parts are increased, and the inlet orifice 205 and the outlet orifice 206 are made. In the fastening of, the processing on the fastening surface must be managed very precisely, and as shown in FIG. 2, the two orifices are connected in such a way that the positions of the high pressure flow path and the low pressure flow path connected to the two orifice plates are fastened regardless of rotation. The method of fastening by installing the groove part in the contact part is used. Therefore, a low precision of machining may lead to leakage of oil on the contact surface, resulting in an injector unevenness.

There is also a control piston guide 213 proposed as a way to facilitate changing the outer diameter of the control piston 202. In the control piston guide 213, the inlet orifice 205 on the upper surface and the injector body 211 on the lower surface are freely rotated, and the lower surface adopts a method of fastening the surface contact with the two parts in a position fixing method by a pin. This is a fastening form of the same method as the fastening of the inlet orifice 205 and the outlet orifice 206 plate, there is a problem that the increase in the number of parts and the degree of processing of the contact surface must be very precise.

Therefore, since the armature valve body 208, the outlet orifice 206, the inlet orifice 205, the control piston guide 213 and the injector body 211 are fastened so as to contact in a plane, leakage of the fastening portion is generated, There is a concern that an increase, an increase in the number of parts, and a high fastening force are required.

In addition, since the fastening of the fuel supply passage 203 and the injector body 211 installed for the fuel supply in the common rail, not shown, adopts a fastening method by a screw part, the outer size of the injector body 211 is increased, making it difficult to miniaturize. And increase the processing time in the processing of the injector body 211, and when the fuel supply passage means 203 is installed in the injector body 211, the processing error between the fuel inlet 203 and the injector body 211 surface May cause fuel leakage. Therefore, since the processing degree of the fuel inlet 203 and the injector body 211 needs to be very strictly managed, there is a problem of increasing the processing time. Although it was conceived to absorb an machining error by installing an elastic body (Gasket) on one side of the fuel inlet 203, this has a problem that the number of parts increases.

In addition, since the valve portion 207 of the solenoid valve 209 directly opens and closes the fuel outlet of the outlet orifice 206 by the operation of the solenoid 212, the solenoid valve 209 when the pressure in the control pressure chamber 204 is very high. Of the valve portion 207 causes the downward force of FIG. 2 to close the outlet orifice 206 to be increased. Therefore, a large force spring force is required, and thus the suction force of the solenoid 212 may also increase considerably. This causes a problem that the appearance of the solenoid 212 is increased, and there is a problem that the size of the injector also increases. In addition, in this direct opening and closing method, the high-pressure fuel flowing out through the outlet orifice 206 when the solenoid 212 is turned off and then turned off causes the injector to restrict the movement of the valve of the solenoid valve 209 to perform the closing action. This may result in non-uniform injection of the injection, thereby causing an injection of the injector.

The present invention has been made to solve such a problem, and an object of the present invention is to provide a fuel injector having a small number of parts, easy processing and mounting, reducing fuel leakage and having a stable injection rate. It is still another object of the present invention to provide a fuel injection device capable of miniaturizing the outer diameter of the fuel injection device at the same time.

1 is an overall explanatory diagram of a accumulator fuel injection device;

2 is an embodiment of a conventional fuel injector

Figure 3 is a cross-sectional view of the fuel injection device of the present invention

4 is an enlarged cross-sectional explanatory view of the main part of the present invention;

4a is a sectional view showing the inlet and outlet orifices of the orifice plate

4b is a cross-sectional view showing the fuel passage and the fixed groove of the low pressure side of the orifice plate.

4c is a cross-sectional view of the circular channel 331

<Description of the symbols for the main parts of the drawings>

301: needle valve 302: control piston

303: fuel inlet 304: inlet orifice

305: outlet orifice 306: orifice plate

307: control pressure chamber 308: armature valve body

309: valve portion 310: solenoid

314: low pressure side connecting passage 315: high pressure side connecting passage

322: injector body 323: solenoid valve

330: connecting passage 331: circular flow path

The technical means for achieving the above-mentioned purpose is that an orifice plate is installed between the injector body and the armature valve body, so that the armature valve body and the orifice plate or the orifice plate and the injector body can each touch the same plane, making it easy to process. The close contact of the plane makes it easy to improve the seal between the armature valve body and the orifice plate, the orifice plate and the injector body without increasing the number of parts. In addition, the armature valve body and the orifice plate can be freely rotated, and the orifice plate and the injector body are firmly fixed by pin fixing means, so that the fuel injection timing can be precisely controlled.

In addition, a connecting passage of the armature valve body, a sliding surface groove portion, a cross-shaped circular flow path, and a connecting passage in the valve portion of the solenoid valve are provided and seated on the protrusion of the orifice plate to control the pressure in the control pressure chamber. Therefore, when the solenoid is OFF, it is precisely closed by a small spring force, and thus the suction force of the solenoid is reduced, and since the external shape of the solenoid can be reduced, the appearance of the injector can be reduced. In addition, when the solenoid is switched from the ON state to the OFF state, the bouncing effect caused by the closing of the valve portion of the solenoid valve is reduced to suppress the injecting of the injector.

EMBODIMENT OF THE INVENTION Hereinafter, the Example which showed embodiment of this invention is described based on drawing.

3 and 4 show the accumulator fuel injection device of the diesel engine according to the embodiment of the present invention.

In the nozzle body 320 of the injection nozzle 321 provided at the lower end of the injector, a needle valve 301 for opening and closing an unshown pore is provided to reciprocately move. The nozzle body 320 and the injector body 322 are joined by a retaining nut 318 by fitting a spacer 324. The semi-injection side of the needle valve 301 is provided with a spring seat 319 and a control piston 302 which is in contact with or connected to the semi-injection side with the spring seat 319.

The control piston 302 is inserted through the spring 317, the spring 317 acts the spring seat 319 in the downward direction of FIG. The fuel is supplied from the common rail (not shown) to the high pressure side fuel passage 314 through the fuel inlet 303. When the needle valve 301 lifts, the high pressure fuel of the high pressure side fuel passage 314 is injected into the injection nozzle 321. Sprayed from the hole of). The semi-injection side cross section of the control piston 302, the inner circumferential wall of the injector body 322, and the lower end of the orifice plate 306 of the inlet orifice 304 and the outlet orifice 305, which will be described later, define the boundary of the control pressure chamber 307. Forming. The connection between the control pressure chamber 307 and the low pressure side fuel passage 314 is controlled by the solenoid valve 309.

One orifice plate 306 is disc shaped and is installed between the injector body 322 and the armature valve body 308. The low pressure side fuel passage 314, the inlet orifice 304, and the outlet orifice 305 are provided in the orifice plate 306 provided on the upper part of the injector body 322, and the low pressure side fuel is provided on the upper end of the orifice plate 306. There is a groove 328 for connection with the passage 314, and at the bottom there is a pinning hole 332 for fastening with the injector body 322.

The armature valve body 308 has a connecting passage 326 for connecting the fuel flowing out through the outlet orifice 305 into the valve portion 309 of the solenoid valve 323, and the valve portion of the solenoid valve 323 ( A groove 329 is formed in the sliding surface of the 309 to facilitate connection with the cross-shaped circular flow path 331 in the valve portion 309 of the solenoid valve 323. In addition, a groove 327 is installed on the lower surface of the armature valve body to facilitate connection and mounting of the flow rate from the outlet orifice 305 with the connection passage 326 of the armature valve body 308.

The injector body 322 is integrally formed with a fuel inlet 303 for connecting the feed fuel from a common rail (not shown) to the high pressure side fuel passage 315, and for fastening with the orifice plate 306. Pin fixing grooves (not shown) are provided.

With the above configuration, the armature valve body 308, the orifice plate 306, and the injector body 322 are in close contact with each other in a plane. The valve portion 309 of the solenoid valve 323 connected to the groove portion 329 of the armature valve body 308 is formed with a cross-shaped circular flow path 331, the connecting passage larger than the diameter of the outlet orifice 305 330 is formed in the downward direction in FIG. 3 to contact the protrusion of the orifice plate 306, and the fuel of the control pressure chamber 307 is discharged to the low pressure side fuel passage 314 by the operation of the solenoid 310. Let's do it.

The solenoid valve 323 is an anisotropic solenoid valve, and is installed above the outlet orifice 305, the armature valve body 308 is coupled to the injector body 322 by a socket 313, and retaining nut ( The solenoid 310, the spacer 312, the solenoid valve 323, the armature valve body 308, and the orifice plate 306 are coupled to the injector body 322 by screwing the 311 and the socket 313.

The operation of the injector according to the present invention configured as described above will be described.

When the solenoid 310 is turned off, the valve portion 309 of the solenoid valve 323 sits on the protruding portion of the orifice plate 306 so that the connection passage 330 in the valve portion 309 of the solenoid valve 323 is blocked. . Therefore, the control pressure chamber 307, the connection flow path 326 in the armature valve body 308, the sliding groove part 329, the cross-shaped circular flow path 331, the connection in the valve portion 309 of the solenoid valve 323 The fuel in the passage 330 is maintained at high pressure so that the pressure in the control pressure chamber is raised. Therefore, the injection is not performed because the control piston 302 is pressed in the downward direction of FIG. 3.

When the solenoid 310 is turned on, the valve portion 309 of the solenoid valve 323 is lifted to oppose the action force of the spring 325 by the suction force of the solenoid 310, and is separated from the protruding portion of the orifice plate 306 by the solenoid valve. The connection passage 330 in the valve portion 309 of 323 is connected to the low pressure side connection passage 314. Accordingly, the fuel of the control pressure chamber controlled by the outlet orifice 305 is controlled by the control pressure chamber 307, the connection flow passage 326 in the armature valve body 308, the sliding groove 329, and the cross-shaped circular flow passage 331. ), The connection passage 330 in the valve portion 309 of the solenoid valve 323 flows out into the low pressure side fuel passage 314, and the pressure in the control pressure chamber 307 drops. At this time, the flow rate flowing out of the control pressure chamber 307 into the low pressure side fuel passage 314 is regulated by the fuel port of the outlet orifice 305, so that the fuel pressure in the control pressure chamber 307 is gently lowered. Accordingly, the needle valve 301 is lifted like the control piston 302 to start fuel injection. At this time, since the needle valve 301 lifts gently, the initial injection rate of the fuel injection may be lowered. The fuel flowing out of the control pressure chamber 307 into the low pressure side fuel passage 314 is discharged to the outside of the injector through the low pressure side fuel passage 314 of the injector body 322 and is refluxed to a fuel tank (not shown).

When the solenoid 310 is turned from ON to OFF, the valve portion 309 of the solenoid valve 323 is seated again on the protruding portion of the orifice plate 306 by the action force of the spring 325 and the valve portion 309 of the solenoid valve 323. Connection in the control pressure chamber 307, the outlet orifice 305 and the low pressure side fuel passage 314 is blocked, so that the connection in the control pressure chamber 307, the armature valve body 308 The pressure in the flow path 326, the sliding part groove part 329, the cross-shaped circular flow path 331, and the connection passage 330 in the valve part 309 of the solenoid valve 323 is increased again to control the pressure chamber 307. When the pressure reaches the predetermined pressure, the needle valve 301 simultaneously moves the hole (not shown) in the closing direction at the same time as the control piston 302, thereby terminating the fuel injection.

As described above, since the fuel injection device of the present invention is in close contact with the injector body 322, the inlet orifice 304, the integral orifice plate 306 of the outlet orifice 305 and the armature valve body 308 in planar contact with each other, It is easy to process, and it can be installed regardless of rotation by using the groove part of each part and the pin fixing pin hole (not shown), and it reduces the leakage of fuel when it is installed, and it is easy to process because both ends of each part are flat shape. There is an effect that the increase in the number of machining and the increase in the number of parts can be suppressed.

In addition, since the pressure control of the control pressure chamber 307 is made by opening and closing of the connecting passage 330 in the valve portion 309 of the solenoid valve 323, the solenoid 310 according to the reduction in the suction force of the solenoid 310 Miniaturization is possible, and the bouncing effect of closing is also reduced, thereby preventing injector irregular injection.

Claims (2)

A high-pressure fuel passage capable of supplying high-pressure fuel from the hole of the injection nozzle of the injector, an injector body having a high-pressure fuel passage, a solenoid valve for controlling the pressure of the control pressure chamber and the control pressure chamber installed at the half injection side of the injection nozzle; In the injector consisting of an orifice plate sandwiched between the injector body and the armature valve body, When the solenoid valve is changed, an orifice plate provided with an outlet orifice machined to have a constant angle regulating the flow rate of fuel flowing out from the control pressure chamber to the low pressure side is used to control the high pressure fuel flowing into the control pressure chamber from the high pressure side fuel passage. An accumulator type fuel injector for a diesel engine, characterized by having an inlet orifice together. A connecting passage is formed in the outlet orifice, and the connecting passage and the valve portion of the solenoid valve are provided with a groove on a sliding surface that slides inside the armature valve body. It is formed to connect with the cross-shaped circular flow path formed in the inside, and the connection passage is formed in the cross-shaped circular flow path and the valve of the solenoid valve to be brought into contact with the projection provided on the orifice plate to raise the fuel pressure of the control pressure chamber, An accumulator type fuel injector for diesel engines, comprising: an armature valve body for discharging high-pressure fuel in the control pressure chamber to the low-pressure side fuel passage by ON.