JPS59101575A - Fuel injection valve for internal-combustion engine - Google Patents

Abstract

PURPOSE:To set a valve opening pressure in accordance with the operation state of an internal-combustion engine by fitting coil springs made of shape memory alloy in series through needle valve spring shoe. CONSTITUTION:A coil spring 10 as a needle valve spring is elastically fitted between a spring shoe 9 and a needle valve receiver 8 which are inserted into a spring chamber 5A, and a coil spring 12 which is made of shape memory alloy having the thermal extension characteristic is elastically fitted between the spring shoe 9 and a spring shoe 11. In a nozzle holder 5, a heating body 14 is fitted in opposed state to the coil spring 12, and a connection wire 14A is connected to the output terminal of an amplifier 20 which amplifies the output voltage of a potentiometer 20 for detecting the turning angle of an acceleration pedal lever. Therefore, the valve opening set pressure for a fuel injection valve 1 can be switched according to the load of an internal-combustion engine.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a fuel injection valve for an internal combustion engine, which is equipped with a coil spring made of a shape memory alloy and whose valve opening pressure can be controlled according to the operating condition of the internal combustion engine.

(Prior Art) A conventional fuel injection valve for an internal combustion engine whose valve opening pressure can be changed is as shown in Utility Model Application No. 56-39862, for example.
Between the needle valve spring that controls the opening and closing of the needle valve of a fuel injection valve for an internal combustion engine and a spring receiver fixed to the valve body, there is an actuating body that expands and contracts due to temperature changes, and a needle that is displaced by the actuating body. Some valve springs are equipped with a column that shortens the length of the valve spring when the temperature rises and extends it when the temperature falls.

However, when using conventional fuel injection valves for internal combustion engines as described above, although the valve opening pressure can be controlled according to the fuel oil temperature, the disadvantage is that the valve opening pressure cannot be controlled according to external signals such as the operating state of the internal combustion engine. was there.

(Object of the Invention) The present invention has been made in consideration of the above-mentioned problems, and provides a fuel injection system for an internal combustion engine that can eliminate the above-mentioned drawbacks and control the valve opening pressure according to an external signal, such as an internal combustion engine operating state detection output. The purpose is to provide a valve.

The present invention will be explained below using examples.

(Configuration in one embodiment of the invention) FIG. 1 is a sectional view of an embodiment according to the present invention.

The fuel injection valve 1 includes a nozzle body 2 in which a valve seat 3 is formed, a needle valve 4 that is inserted into the nozzle body 2 so as to be movable in the axial direction and controls the injection opening, the nozzle body 2 and a nozzle holder 5. It includes an intermediate member 6 interposed therebetween, and a cap nut 7 that fixes the nozzle main body 2, nozzle holder 5, and intermediate member 6 to each other and integrates them. A needle valve receiver 8 whose one end extends to the spring chamber 5A in the nozzle holder 5 is fitted on the rear end side of the needle valve 4. A coil spring 10 as a needle valve spring is elastically inserted between the spring receiver 9 inserted into the spring chamber 5A and the needle valve receiver 8. A coil spring 12 made of a shape memory alloy that expands when heated is elastically inserted between the spring receiver 11 and the spring receiver 11 . The spring receiver 11 has a spring adjustment bolt 13 screwed onto the nozzle holder 5 with a portion protruding from the nozzle holder 5.
It is pressed against the tip of the

On the other hand, in the nozzle holder 5, a heating body 14 formed in a coil shape by winding a resistance wire is mounted in a manner that is electrically insulated from the nozzle holder 5, facing the coil spring 12. The connecting wire 14A of the heating element 14 passes through a through hole 18 provided in the nozzle holder 5 and is led out of the fuel injection valve 1, and is connected to the output voltage of a potentiometer 20 that detects the rotation angle of an accelerator pedal lever (not shown). It is connected to the output terminal of an amplifier 20 that amplifies the . Note that a filling body 19 is provided in the through hole 18.
is installed.

On the other hand, an oil reservoir chamber 15 is formed in the nozzle body 2, and a nozzle holder 5 is formed in the nozzle holder 5 and the intermediate member 6.
and 16A of oil holes that penetrate through the intermediate member 6 and communicate with each other.
and 16B are perforations. The nozzle body 2 is provided with an oil passage hole 16C that communicates the oil reservoir chamber 15 with the oil passage hole 16B. The nozzle holder 5 is provided with an oil passage hole 17 that lubricates the needle valve 4 and guides the fuel oil that returns to the spring chamber 5A to an oil tank (not shown) through the gap between the nozzle body 2 and the needle valve 4. It is.

(Operation of an embodiment of the invention) In an embodiment of the invention configured as described above, when fuel oil is not supplied from the fuel injection pump (not shown), the pressure of the coil springs 1o and 12 is applied to the needle valve holder. 8, the needle valve 4 is pushed down as shown in FIG. 1, the needle valve 4 and the valve seat 3 come into contact with each other, the injection opening is closed, and no fuel injection is performed.

When fuel oil is supplied from the fuel injection pump, the fuel oil is guided to the oil reservoir chamber 15 through the oil passage holes 16A, 16B, and 16C. Thereupon, the needle valve 4 receives the pressure of the fuel oil in the oil reservoir chamber 15 and moves upward in FIG. 1 against the pressing force of the coil springs 1o and 12, and the fuel injection valve 1 becomes open. , fuel oil is injected from the injection opening. In this case, the opening pressure of the fuel injection valve 10 is determined by the pressing force of the coil springs 1o and 12.

However, in one embodiment of the present invention, the coil spring 12 is made of a shape memory alloy, and a heating element 14 is provided opposite to the coil spring 12, and the heating element 14 is heated by the rotation of the accelerator pedal lever. Potentiometer 2 that detected the corner
It is heated by the current amplified by the amplifier 21 from the zero output voltage. Therefore, when the internal combustion engine is in idle-link operation, the output voltage of the potentiometer 20 is low, the output current of the amplifier 21 is low, and the temperature of the heating element 14 is low. As a result, the temperature of the coil spring 12 is low, and the coil spring 1
The length of coil spring 2 is maintained in a contracted state, and the length of coil spring 10 is in an expanded state.

Therefore, the valve opening pressure is set low. Furthermore, when the load on the internal combustion engine increases, the output voltage of the potentiometer 21 increases via the accelerator pedal lever, the output current of the amplifier 21 increases, and the heating element 14 is heated.
The temperature of the heating element 14 increases. As the temperature of the heating element 14 increases, the temperature of the coil spring 12 increases, and the temperature of the coil spring 12 increases.
The length of becomes elongated. As a result, coil spring 1
A length of 0 results in a reduced state. Therefore, the valve opening pressure is set high.

Then, when the load is reduced, the output of the potentiometer 20 decreases, and the output current of the amplifier 21 decreases, causing the output current of the heating element 14 to decrease.
temperature decreases. As the temperature of the heating element 14 decreases, the coil spring 12 is contracted by the force of the coil spring 10 and returned to its original state. As a result, the coil spring 10 is expanded and the valve opening pressure is set low.

That is, the set valve opening pressure of the fuel injection valve 1 is changed depending on the load of the internal combustion engine.

In addition, in one embodiment of the present invention described above, the heating body 1
4 is heated according to the load of the internal combustion engine, but the output voltage of the rotation speed detector that detects not only the load of the internal combustion engine but also the rotation speed of the crankshaft of the internal combustion engine is supplied to the amplifier 21. The heating element 14 is heated by the output current of 21.
By heating the valve, the valve opening pressure can be set low during low speed rotation, and the valve opening pressure can be set high during high speed rotation.

Further, the load state of the internal combustion engine is detected based on a load detection signal that detects the load of the internal combustion engine and a rotation speed detection signal that detects the rotation speed of the internal combustion engine, and an output obtained by amplifying the detection signal is supplied to the heating body 14. The heating element 14 may be heated according to the load condition of the internal combustion engine.

Next, a modified example of one embodiment of the present invention will be described.

(Structure of Modified Embodiment of One Embodiment of the Invention) FIG. 2 is a sectional view of the main parts showing a modified embodiment of one embodiment of the present invention.

In a modified embodiment of the embodiment of the present invention, a coil spring 10 as a needle valve spring is accommodated in five spring chambers provided in the nozzle holder 5 by a spring receiver 9A slidably provided within the spring chamber 5A. spring chamber 5
A1 and a coil spring 12 made of shape memory alloy
The coil spring 10 is inserted between the nine spring receivers and the needle valve receiver 8, and the coil spring 12A is inserted between the nine spring receivers and the nozzle holder 5. . On the other hand, nozzle holder 5
A heating body 14]3 is attached to the outer periphery of the nozzle holder 5 facing the coil spring 12A via the nozzle holder 5. On the other hand, potentiometer 2 detects the rotation angle of the accelerator pedal lever.
The output current of the inverting amplifier 21A that inverts and amplifies the zero output voltage is supplied to the heating body 14B via the connection line 14A.

Here, the coil spring 12A is formed of a shape memory alloy whose characteristics are opposite to those of the coil spring 12, that is, a shape memory alloy whose characteristics shrink when heated.

(Operation in a modified embodiment of one embodiment of the present invention) In this modified embodiment, when the internal combustion engine is in idle-link operation, the output voltage of the potentiometer 20 is low, the output current of the inverting amplifier 21A is large, and the heating element 14B is heated to a high temperature.

Therefore, the coil spring 12A is heated and no longer maintains its shape, and is compressed by the force of the coil spring 10, causing the spring receiver 9A to rise in FIG. 2 and come into contact with the step at the boundary between the spring chambers 5A1 and 5A2. , the force of the coil spring 10 is weakened and the valve opening pressure is reduced. Also, when the load on the internal combustion engine increases, the potentiometer 2
The output voltage of 0 increases, the output current of the inverting amplifier 21A decreases, and the temperature of the heating element 14B decreases. Heating body 14B
Due to the temperature drop, the coil spring 12A enters a shape memory state, that is, the coil spring 12A is expanded, and the coil spring 10 is compressed and its length is reduced. Therefore, the valve opening pressure of the fuel injection valve 1 increases.

Further, the heating element 14B may be heated by the output detected by the crankshaft rotation speed of the internal combustion engine instead of the load of the internal combustion engine, and the heating element 14B may be heated according to the operating state of the internal combustion engine.
may be heated.

(Effects of the Invention) As explained above, according to the present invention, a coil spring made of a shape memory alloy is inserted into a spring chamber in series with a needle valve spring of a fuel injection valve via a spring receiver, and Since a heating element that heats the coil spring is attached to the valve body, the opening pressure of the fuel injector can be controlled by an external signal, and the opening pressure of the fuel injector can be controlled by an external signal. It is possible to set the valve opening pressure according to the operating state of the internal combustion engine, such as by setting the valve opening pressure of the fuel injection valve to be low and high during high speed rotation or high load operation. Further, the configuration for this purpose is also simple.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing one embodiment of the present invention. FIG. 2 is a sectional view showing the main parts of a modified embodiment of the present invention. 1. Fuel injection valve, 2. Nozzle body, 3. Valve seat, 4
... Needle valve, 5... Nozzle holder, 5A15A1 and 5A2 - Spring chamber, 6... Intermediate member, 7
... Bag nut, 8... Needle valve holder, 9 and 9A...
Spring receiver, 10...Coil spring as needle valve spring, 12 and 12A...Coil spring, 14 and 14B
... Heating body, 14A... Connection wire, 20 - Potentiometer, 21... Amplifier, 21A... Inverting amplifier. Nobuo Sunako, Patent Attorney, Patent Attorney, Patent Applicant, Diesel Kiki Co., Ltd. Figure 1

Claims (1)

[Claims] A fuel injection valve for an internal combustion engine, comprising a needle valve spring inserted into a spring chamber provided in a valve body and abutting the needle valve receiver to elastically press the needle valve against the valve seat,
A coil spring made of a shape memory alloy is inserted into the spring chamber in series with the needle valve spring via a spring receiver, and a heating element that heats the coil spring in response to an external signal is attached to the valve body. Features of fuel injection valves for internal combustion engines.