KR200180571Y1 - Unit injector for diesel engine using piezo-electric material - Google Patents

Abstract

It is a unit injector for a diesel engine that controls the injection amount and the timing of injection of fuel injected through the needle valve into the combustion chamber by opening the passage of fuel supplied from the feed pump and sent to the high pressure chamber, which is sent from the feed pump to the high pressure chamber. In the diesel engine unit injector for controlling the injection amount and the injection timing of the fuel injected into the combustion chamber through the needle valve by opening and closing the passage of the fuel, a plurality of plate-like piezoelectric body laminated through the space formed in the upper part of the spill chamber, The piston is fixedly coupled to the lower portion, but the spring is installed in the lower portion thereby to raise and lower the needle valve.

Description

Unit injector for diesel engine using piezoelectric body

The present invention relates to a unit injector for a diesel engine using a piezoelectric body, and in particular, to improve the operation structure of the needle valve that can improve the operation response to control the injection state of the fuel.

As is well known, the unit injector has been developed to remove dead-volume space caused by the injection pipe installed between the injection nozzle and the injection pump. It is formed by the unit of.

Such a unit injector is provided with a spill chamber 5 through which fuel supplied from a feed pump (not shown in the drawing) passes through a fuel passage 3 in which a fuel inlet 1 is formed, as shown in FIG. When the solenoid valve 7 is lowered by the spring 9 force, the fuel passage 3a is opened, and the plunger 13 linked with the cam 11 acts as the plunger spring 15 force. Filled by the high pressure chamber 17, the solenoid 21 is excited again and the stator 23 is excited so that the solenoid valve 7 overcomes the spring 9 and the fuel passage 3a is closed. When the plunger 13 interlocked with the rocker arm 19 is lowered by the driving of the cam 11, the fuel pressure compressed by the plunger 13 is applied to the spring 27 force of the needle valve 25. When exceeded, the needle valve 25 is lifted and opened to form a structure that is injected into the combustion chamber .

In addition, after the measured fuel amount is injected, the energization of the solenoid 21 is interrupted, the solenoid valve 7 is lowered by the spring 9 force, and the fuel passage 3a is opened, so that the fuel is spilled passage 3b. It is configured to return to the fuel tank through.

Here, the solenoid valve 7 is coupled to the armature (aa), being raised by the electromagnetic force of the stator 23, which is energized when the solenoid 21 is energized, and lowered by the force of the spring 9, The fuel passage 3a is continuously opened and closed to control the injection amount and the injection timing of the fuel.

The operation method of the conventional solenoid valve 7 described above has a problem in that responsiveness is lowered by the force of the spring 9.

For example, the solenoid valve 7 must have a large electromagnetic force of the stator 23 in order to overcome the spring 9 force. In addition, when the spring 9 force is lowered, the responsiveness is lowered. On the contrary, when the spring force 9 is excessive, the responsiveness is lowered when the solenoid valve 7 is raised.

The present invention has been proposed for the purpose of solving the above-described problems of the prior art, and the solenoid valve is not driven by the spring force, so that the piezoelectric element is inflated and contracted by a short circuit of the electric current so that the needle valve is elevated. It is an object of the present invention to provide a unit injector for a diesel engine using a piezoelectric body to improve the response of a needle valve and fuel injection.

1 is an overall cross-sectional view showing a unit injector for a general diesel engine.

2 is a partial cross-sectional view of a unit injector for a diesel engine according to the present invention,

(a) is an explanatory diagram of the action of the piezoelectric body when it is expanded,

(b) is an explanatory view of the action when the piezoelectric body shrinks.

3 is a perspective view of a needle valve of a unit injector for a diesel engine according to the present invention.

* Explanation of symbols for main parts of the drawings

2: piston 4: space part

5: spillroom 6: piezoelectric body

8: spring 12: spring seat

14: spring 16,16 ′: groove

20 Fluid 25 Needle Valve

Hereinafter, a preferred embodiment of the present invention will be described in more detail with reference to the accompanying drawings.

2 is a cross-sectional view showing a structure of a unit injector for a diesel engine using a piezoelectric body according to the present invention, in which the main part of FIG. 1 is enlarged.

In describing the present invention, the same reference numerals will be used for the clarity of description for the configuration of the present invention that is the same as the drawings cited in the prior art. In addition, it demonstrates in detail with reference to the structure of FIG.

Reference numeral IB in the figures refers to the body of the unit injector individually attached to each cylinder of the engine using a retainer nut, not shown.

One side of the unit injector body IB is supplied from a feed pump (not shown), and opens and closes the passage 3a and the spill chamber 5 of the fuel which is sent to the high pressure chamber 17 and compressed by the plunger 13. Therefore, the assembly using the piezoelectric body of the present invention which controls the injection amount and injection timing of the fuel injected into the combustion chamber via the needle valve 25, and opens the spill passage 3b of the fuel returned to the fuel tank is mounted.

One side of the unit injector body IB includes a flow path 3a connected to a feed pump, a flow path 3a penetrated through the high pressure chamber 17, and a spill chamber 5 through which the fuel tank and a spill flow path 3b penetrate. In the upper portion, the space portion 4 is configured, but communicates with the spill chamber 5 described above.

The space part 4 is formed of a piezoelectric material (a material having a property of converting electrical energy into strain energy or transforming energy into electrical energy, and in the present invention, the property of converting electrical energy into strain energy is used.). A plurality of plate-like piezoelectric elements 6 are laminated, and a lower portion of the piston 2 is fixed to the disk-like piston 2, and a spring 8 is mounted in the lower portion of the piston 2.

In addition, a needle valve 25 is formed in the spill chamber 5, and a spring seat 12 is coupled to the lower portion thereof, whereby another spring 14 is provided between the needle valve 25 and the spring seat 12. The needle valve 25, which is drunk and electric, is configured in the form of a multi-stage cylindrical body so as to slide a passage through which the space 4 and the spill chamber 5 penetrate, and the lower portion of the needle valve 25 is configured as a cylindrical body having a wider diameter. The upper side is configured with a downward inclined portion and the inclined portion is configured with a plurality of grooves (16, 16 ') to flow.

In this structure, the fluid 20 is filled in the space between the lower surface of the piston 2 and the upper surface of the needle valve 25 to be used as a medium for elevating the needle valve 25.

The operation of the present invention configured as described above will be described in detail.

The unit injector according to the present invention, like the conventional unit injector, as shown in FIG. 2 (a), has a flow passage 3a connected to a feed pump and a passage 3a penetrated into the high pressure chamber 17, and a spill penetrated with the fuel tank. The spill chamber 5 penetrates the flow passage 3b, and the injection timing is adjusted by opening and closing the flow passage 3a of the high pressure chamber 17 by the needle valve 25 up and down.

However, in the up and down lifting action of the needle valve 25, a plurality of piezoelectric elements 6 deformed by the power source 18 are laminated without being formed by existing solenoids and amateurs. Likewise, the current applied from the power source 18 expands the piezoelectric member 6 and the piston 2 coupled to the lower part of the piezoelectric member 6 moves downward, and the fluid 20 in the lower space of the piston 2 is pressurized. As this rises, the needle valve 25 is pushed out so that the flow path 3a of the fuel flowing from the feed pump and the flow path 3a penetrated into the high pressure chamber 17 are blocked, and the rocker arm is rotated by the cam 11. When 19 operates, the plunger 13 descends to compress the high pressure chamber 17 to inject fuel. In addition, even if the needle valve 25 is raised so that the lower cylindrical portion of the needle valve 25 seats on the unit injector body IB, fuel may continue to spill by the lower grooves 16 and 16 'of the needle valve 25. It is.

As shown in FIG. 2 (b), when the power source of the piezoelectric element 6 is cut off, the piezoelectric element 6 contracts, so that the piston 2 rises due to the action of the spring 8, and the fluid 20 in the lower space of the piston 2. ) Is in a state where the pressure is lowered, the needle valve 25 is raised by the action of the lower spring 14 of the needle valve 25, so all of the flow paths 3, 3a and 3b are opened, so that the flow path from the feed pump Fuel is introduced through (3), which is spilled into the high-pressure chamber 17 and the fuel tank so that the spraying state is maintained.

As described above, since the up and down lifting action of the needle valve flows due to the contraction and expansion of the piezoelectric body, the needle valve has a relatively small load during the lifting and lowering operation, thereby improving the response.

In addition, since the responsiveness is improved, there is also an effect that the adjustment performance of the injection amount and the injection timing of the fuel is improved.

Claims (4)

In the diesel engine unit injector which controls the injection amount and timing of injection of fuel injected into the combustion chamber through the needle valve by opening and closing the passage of fuel sent from the feed pump to the high pressure chamber, the plate-shaped portion is formed in the space formed through the upper part of the spill chamber. A multilayer injector for a diesel engine using a piezoelectric body, comprising a plurality of piezoelectric elements, and fixedly engaging a piston on a lower portion thereof, and arranging springs thereunder, thereby raising and lowering the needle valve. The injector for a diesel engine using a piezoelectric body according to claim 1, wherein the diameter of the piston is larger than that of the needle valve. The injector for a diesel engine using the piezoelectric body according to claim 1, wherein the down seating portion and the up seating portion are formed above and below the needle valve so that the needle valve reciprocates by a distance between the upper and lower seating portions. 4. The injector for a diesel engine using a piezoelectric body according to claim 3, wherein an outflow groove of fuel is formed on a surface of the upper seating portion.