JPH0462983A - Electrostrictive type actuator - Google Patents

Abstract

PURPOSE:To accurately operate an actuator of a simple structure irrespective of a temperature change by correcting a current amount flowing through an electromagnetic coil in response to a temperature change near supermagnetstriction to be elongated or contracted according to a variation in a magnetic field generated by the coil. CONSTITUTION:An oil sucking chamber 7 is formed of a supermagnetstrictive alloy 10 at its right end face, an electromagnetic coil 11 is disposed at its outside, and the coil 11 is energized by a controller 12 having a CPU, etc., therein. Thermocouples 13, 14 for detecting temperatures in the vicinity are disposed at the upper and left ends of the alloy 10, and its temperature signal is input to the controller 12. The two thermocouples are provided so as to accurately correct the temperature in response to a temperature distribution therein since the temperatures are different in the alloy 10. The controller 12 serves to increase the current flowing to the coil 11 with the rise in the temperature detected by the thermocouples 13, 14, so as to compensate for the temperature characteristics in which the elongation of the alloy 10 decreases with the rise in its temperature.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to improvements in electrostrictive actuators, and particularly to measures to improve control accuracy of their operations.

(Prior Art) Conventionally, as an electrostrictive actuator, as disclosed in JP-A-60-104762, for example, an electrostrictive actuator has an electrostrictive element made of a piezoelectric element that undergoes strain displacement when a voltage is applied. In addition to transmitting the strain displacement of the electrostrictive element to the outside, by circulating a cooling medium around the outer periphery of the electrostrictive element, the electrostrictive element is cooled and the strain caused by the temperature change is reduced. There are known devices that suppress changes in the amount of displacement. In addition, as a means for temperature-correcting the strain displacement of the electrostrictive element, a pressing member made of a shape memory alloy for pressing the electrostrictive element is arranged on the side of the electrostrictive element, and a pressing member is arranged near the electrostrictive element. When the temperature of the shape memory alloy changes, the pressing force applied to the electrostrictive element is changed by changing the shape of the shape memory alloy, and the amount of expansion and contraction of the electrostrictive element is adjusted. Another electrostrictive element with a small volume is additionally installed on the side, and the amount of strain displacement of the electrostrictive element is detected by the other electrostrictive element, and the voltage applied to the electrostrictive element is corrected. be.

(Problem to be Solved by the Invention) However, regarding temperature correction of strain displacement, it is difficult to maintain a constant temperature of the electrostrictive element even if the cooling medium is circulated as in the above conventional method, and the structure is also complicated. become. Furthermore, when a shape memory alloy is used, the alloy follows fine temperature changes well and does not change. Furthermore, when an electrostrictive element with a small volume is additionally installed, the strain displacement of the electrostrictive cable cannot be accurately detected due to the small volume. In other words, all of the above-mentioned conventional devices have the disadvantage that strain displacement cannot be accurately corrected for temperature.

Furthermore, when using a piezoelectric element, it is necessary to take out the lead wire directly from it, which causes problems in terms of peeling of the connection part and sealing of the lead wire take-out part, and its laminated structure makes it brittle and has poor durability. , it also has the disadvantage of low reliability.

The present invention has been made in view of the above, and an object of the present invention is to provide an electrostrictive actuator that has a simple configuration, can accurately correct temperature for strain displacement regardless of temperature changes, and can operate with high precision. It's about doing.

(Means for Solving the Problems) In order to achieve the above object, in the present invention, a giant magnetostrictive body is used instead of an electrostrictive element such as a piezoelectric element, and the super magnetostrictive body is Corrects the strength of the magnetic field that causes distortion and displacement.

That is, a specific configuration of the present invention includes an electromagnetic coil that generates a magnetic field and a giant magnetostrictive body that expands and contracts due to changes in the magnetic field generated by the electromagnetic coil. Furthermore, a temperature detection means for detecting the temperature near the giant magnetostrictive body, and a correction means for correcting the amount of current flowing through the electromagnetic coil according to a change in the temperature near the giant magnetostrictive body detected by the temperature detection means. The configuration is such that it is provided.

(Function) With the above configuration, in the electrostrictive actuator of the present invention, the strength of the magnetic field formed by the electromagnetic coil causes strain displacement of the giant magnetostrictive body within the magnetic field, and a change in the strength of the magnetic field. Accordingly, the amount of strain displacement changes.

Furthermore, when the temperature near the giant magnetostrictive body changes, the amount of current applied to the electromagnetic coil is corrected by the correction means, so the amount of strain displacement of the giant magnetostrictive body remains at the target value regardless of the temperature change near the giant magnetostrictive body. Therefore, the temperature will be corrected.

Temperature correction of the amount of strain displacement is performed by correcting the current flow rate to the electromagnetic coil, so it is possible to have a simple configuration, and the strain displacement can be finely corrected according to temperature changes, making it possible to compensate for temperature changes. It is possible to perform accurate movements regardless of the situation.

(Effects of the Invention) As explained above, according to the electrostrictive actuator of the present invention, a giant magnetostrictive body is used as an element to be strain-displaced, and the current flow rate of the electromagnetic coil for strain-displacing this body is adjusted near the giant magnetostrictive body. Since the correction is made in accordance with the temperature change, the amount of strain displacement can be finely corrected in accordance with the temperature change with a simple configuration, and highly accurate operation can be performed.

(Example) Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows a first embodiment applied to a distribution type fuel injection pump used in a diesel engine, and 1 is a plunger for pumping fuel, and the plunger is used to inject fuel in a fuel chamber 2. A suction port 1a for inhaling and the suction port 1
a vertical hole 1b formed in the axial direction and communicating with the vertical hole 1b;
The fuel injection nozzle 1c has a distribution port 1c that communicates with the fuel injection nozzle and distributes the fuel to the plurality of fuel injection nozzles.

A face cam 5 that rotates in synchronization with the engine is connected and fixed to the left side of the plunger 1 in the figure.
A cam 6 is engaged with the cam surface 5a. On the other hand, a suction oil chamber 7 is formed on the right side of the plunger 1 in the drawing.

The plunger 1 is then rotated by the rotational action of the face cam 5.
While rotating, the engagement of the face cam 5 with the cam 6 gives the plunger 1 a reciprocating motion in the left-right direction in the figure. 7, and during its forward movement, the suction port la is closed and the fuel in the suction oil chamber 7 is supplied from the vertical hole 1b to the distribution port 1c.
The configuration is such that the fuel is pumped from the fuel injection nozzle to the corresponding fuel injection nozzle. In the figure, 8 is a spill ring that adjusts the amount of fuel pumped, and 9 is a spill ring that adjusts the amount of fuel pumped.
is a delivery pulp that sucks back the remaining fuel after being injected from the fuel injection nozzle.

Further, as a feature of the present invention, the suction oil chamber 7 has a right end surface in the drawing formed of a giant magnetostrictive alloy 10 as a giant magnetostrictive body, and an electromagnetic coil 11 is disposed outside the giant magnetostrictive alloy 10. The electromagnetic coil 11 is supplied with power from a controller 12 having a CPU and the like therein. Therefore, the electromagnetic coil 11
When energizing, a magnetic field with a strength corresponding to the amount of energization is generated in the space containing the giant magnetostrictive alloy 10, and the giant magnetostrictive alloy 10 is expanded by the strength of the magnetic field. The configuration is such that the volume of the chamber 7 is made variable to adjust the pressure of the fuel that is force-fed from the distribution port 1c of the plunger 1 to the fuel injection nozzle.

At the upper and left ends of the giant magnetostrictive alloy 10 in the figure, respectively, there are thermocouples 13 as temperature detection means for detecting the temperature in the vicinity of the giant magnetostrictive alloy 10. 14 is arranged, and its temperature signal is input to the controller 12. The reason why the two thermocouples are provided is to perform temperature correction with high accuracy in accordance with the temperature distribution inside the giant magnetostrictive alloy 10 since the temperature varies inside the giant magnetostrictive alloy 10.

As shown in FIG. 2, the controller 12 controls the electromagnetic coil 1 as the temperature detected by the thermocouple 13.14 increases.
The temperature characteristic in which the amount of elongation of the giant magnetostrictive alloy 10 becomes smaller as the temperature of the giant magnetostrictive alloy 10 becomes higher is compensated for by increasing the current flow rate to the super magnetostrictive alloy 10.

Therefore, the controller 12 controls the two thermocouples 1
According to the change in temperature near the giant magnetostrictive alloy 10 detected in step 3.14, the correction means 15 is configured to increase the amount of current supplied to the electromagnetic coil 11 as the temperature increases.

Therefore, in the above embodiment, if the temperature near the giant magnetostrictive alloy 10 becomes high due to the engine operating at high speed and high load, for example, even if the same amount of current flow is applied to the electromagnetic coil 11. The amount of elongation of the giant magnetostrictive alloy 10 is smaller than when the temperature is low, and therefore the volume of the suction oil chamber 7 is expanded by that amount, and the fuel injection pressure is reduced.

However, as shown in FIG. 3, since the temperature near the giant magnetostrictive alloy 10 is high, the current flow rate to the electromagnetic coil 11 is the normal value.
The amount of elongation of the giant magnetostrictive alloy 10 increases by a correction increase amount of 1o, and the amount of elongation of the giant magnetostrictive alloy 10 increases to an appropriate amount, so that a predetermined injection pressure can be obtained.

FIG. 4 shows a second embodiment in which the present invention is applied to a fuel injection nozzle for a diesel engine. In the fuel injection nozzle A in the figure, a recess 2 formed at the tip of the nozzle body 20
A fuel passage 21 is open at 0a, and a freely slidable needle valve 22 is seated to close the recess 20a.

A pressure spring 23 is attached to the rear end of the needle valve 22.
An oil chamber 24 is formed behind the tray 23a.

An electromagnetic coil 26 is disposed outside the giant magnetostrictive alloy 25 disposed on the rear end surface of the oil chamber 24 . When the giant magnetostrictive alloy 25 is in the expanded state, the volume of the oil chamber 24 is reduced accordingly, and the pressure of the pressure spring 23 is increased by the oil pressure of the oil chamber 24, so that the needle valve 22 is unseated. It is configured to increase the fuel pressure by that amount. Further, a temperature sensor 27 is arranged around the oil chamber 24 to detect the temperature of the fuel in the oil chamber 24 and to detect the temperature near the giant magnetostrictive alloy 25. In addition, 28 in the figure is the oil chamber 24.
This is a one-way valve installed in an oil passage 29 that communicates and connects the pressure spring 23 and the pressure spring 23.
This prevents the fuel in the oil chamber 24 from leaking into the chamber in which the pressure spring 23 is arranged when the pressure spring 5 is extended. Other than that, the installation of the controller and the temperature correction of the current flow rate are the same as in the first embodiment, so illustrations and explanations thereof will be omitted.

Therefore, in this embodiment, when the controller controls the flow rate of current to the electromagnetic coil 26 to increase in response to an increase in engine speed or an increase in engine load, as shown in FIG. When the current flow rate is small under load, as shown in FIG. 6(a), the amount of expansion of the giant magnetostrictive alloy 25 is small, and the pressure spring 23
The pressing force does not increase much and becomes the force F1, so when the fuel pressure rises to the above force F1, the needle valve 22 is unseated and fuel at this fuel pressure is injected. On the other hand, when the rotation is high and the current flow rate is large, the amount of elongation of the giant magnetostrictive alloy 25 increases, as shown in FIG.
(>Fl), so fuel is injected at pressure F2.

At this time, as in the first embodiment, the current flow rate to the electromagnetic coil 26 is corrected so that it increases as the temperature increases, depending on the temperature near the giant magnetostrictive alloy 25, so the super magnetostrictive alloy Even if the temperature around 25 changes in height, fuel can be injected and supplied at a fuel pressure that matches the operating conditions at that time. In addition, in the above second embodiment,
The plate 23a of the receiver of the pressure spring 23 may be formed of a giant magnetostrictive base metal.

Furthermore, when the electrostrictive actuator of the present invention is applied to a fuel injection nozzle, a heater 30 is placed in the nozzle body between the giant magnetostrictive alloy 25 and the electromagnetic coil 26, as shown in FIG. . This heating heater 30 is for heating the giant magnetostrictive alloy 25 and raising its temperature when the engine is cold. In other words, as shown in Figure 8, when the engine is cold and the temperature near the giant magnetostrictive alloy 25 detected by the thermocouple is low, a message saying "Engine preparing to start" is displayed around the driver's seat.
is displayed, the heater 30 is energized to raise the temperature of the giant magnetostrictive alloy 25, and the temperature reaches the set value (0 in the figure).
℃), the amount of current applied to the heating heater 30 is gradually reduced, the display around the driver's seat is changed to "ready to start", and the electromagnetic coil 26 starts being energized. As a result, even if the giant magnetostrictive alloy 25 has a temperature characteristic with a small strain displacement rate at low temperatures, it is possible to inject fuel at the set fuel pressure while keeping the valve opening pressure of the needle valve 22 in line with the set value.
Good engine startability can be obtained. The heater 30 described above may be installed inside the electromagnetic coil 11 of the first embodiment.

FIG. 9 shows a third embodiment applied to a delivery valve B provided in a distribution type fuel injection pump of a diesel engine. In delivery valve B in the same figure, valve seat 3
In the internal space of 4, a valve body 36 and a relief valve 37 disposed below the valve body 36 are provided so as to be vertically slidable. The valve body 36 and the relief valve 37 are connected by a rod-shaped giant magnetostrictive alloy 39 arranged in the vertical direction, and an electromagnetic coil 40 is arranged on the valve body 36 at the outer circumference of the giant magnetostrictive alloy 3903. . In addition, the valve seat 34
An electromagnetic coil 41 is disposed around the outer periphery of the relief valve 37 to move the relief valve 37 upward in the figure.

Furthermore, in the central part of the internal space of the valve seat 34,
A leak chamber 4 that stores fuel by cutting out the portion in the radial direction
A temperature sensor 43 is arranged near the leak chamber 42 to detect the temperature of the fuel in the leak chamber 42, and its temperature signal is input to the controller 45.

As shown in FIG. 10(a), the controller 45 is configured such that the higher the engine speed, the higher the pressure at the end of fuel injection in the fuel pipe leading to the fuel injection nozzle.
Since it is necessary to increase the amount of fuel sucked back into 2, the same figure (
As shown in b), the larger the amount of fuel sucked back into the leak chamber 42, the greater the amount of electricity supplied to the electromagnetic coil 40, and the higher the fuel temperature, the more the electromagnetic coil 40 is controlled.
It has a control function to increase the amount of electricity supplied to the

In addition, in FIG. 9, 46 is a spring that biases the valve body 36 in the seating direction.

Therefore, in the above embodiment, when the electromagnetic coil 41 is energized to raise the relief valve 37 and the valve body is unseated against the spring 46, as shown in FIG. 11(A), Inject the fuel inside. and,
At the end of fuel injection, when the engine is running at high speed, the residual pressure in the fuel pipe is high and a large amount of fuel is required to be sucked back into the leak chamber 42. Therefore, the current flow rate to the electromagnetic coil 40 is reduced as shown in FIG. Increasing according to (b), giant magnetostrictive alloy 39
extends vertically, and as shown in FIG. 11 (b), the valve body 36
The distance between the leak chamber 4 and the relief valve 37 is GL.
The volume of 2 increases. As a result, a large amount of fuel is sucked back into the leak chamber 42, and the residual pressure in the fuel pipe becomes a good pressure suitable for high engine rotation. On the other hand, when the engine rotates at low speeds, the amount of current supplied to the electromagnetic coil 40 is small, and the giant magnetostrictive alloy 39 does not expand much. As a result, as shown in FIG. 11(C), the distance between the valve body 36 and the relief valve 37 does not widen so much and becomes Ω2 (Q+), and the amount of fuel sucked into the leak chamber 42 does not increase significantly. Good residual pressure suitable for low engine speed.

Moreover, the higher the fuel temperature near the giant magnetostrictive alloy 39, the greater the flow rate of current to the electromagnetic coil 40.
Since the strain displacement amount of 9 is corrected by temperature as in the first embodiment, it is possible to obtain a residual pressure in the fuel pipe that matches the engine operating condition, prevent fuel leakage and cavitation, and improve fuel injection. It is possible to improve the durability of the nozzle.

FIG. 12 shows a configuration for detecting displacement of a needle valve of a fuel injection nozzle of a diesel engine. In the same figure, the needle valve 50
A giant magnetostrictive alloy 53 is disposed between the rear end of a pressure spring 51 that biases the valve body in the seating direction and a plate 52 for its support, and an electromagnetic coil 54 is disposed around the outer periphery of the giant magnetostrictive alloy 53 of the valve body. A lead wire 55 is connected to the electromagnetic coil 54.

Therefore, when the needle valve 50 is unseated and moves upward, the pressure spring 51 contracts and the giant magnetostrictive alloy 53 moves to the position shown in FIG. 13(b) from the normal state shown in FIG. As shown, the width g1 contracts to Ω2(C,C)I), and due to this displacement, a magnetic field corresponding to the amount of displacement is generated due to the properties of the giant magnetostrictive alloy 53, and as a result, the electromagnetic coil 54 has the above-mentioned supermagnetostrictive alloy. A current flows in accordance with the direction and magnitude of the strain displacement of the magnetostrictive alloy 53 (see FIG. 14), and this current is taken out from the nine-domain wire 55. Therefore, as shown in FIG. 15, if the current flowing through the electromagnetic coil 54 is passed through the resistor R and the voltage across it is detected by the voltmeter 56, the needle valve 50
The amount of displacement can be detected.

[Brief explanation of drawings]

The drawings illustrate embodiments of the invention. 1 to 3 show a first embodiment of the present invention, FIG. 1 is a diagram showing the main part configuration of a fuel injection pump, and FIG. A diagram showing the flow rate characteristics, and FIG. 3 is an explanatory diagram of the operation. 4 to 8 show a second embodiment of the present invention, FIG. 4 is an overall configuration diagram of a fuel injection nozzle, FIG. 5 is a diagram showing current flow rate characteristics with respect to engine speed and engine load, and FIG. FIG. 6 is an explanatory diagram of the operation, FIG. 7 is an overall configuration diagram of the fuel injection nozzle when a heater is provided, and FIG. 8 is an explanatory diagram of the timing of energizing the heater and the electromagnetic coil. 9 to 11 show a third embodiment of the present invention, FIG. 9 is an overall configuration diagram of a delivery valve, and FIG. 10 is a diagram showing fuel sucking back amount characteristics with respect to engine speed and fuel sucking back stars. FIG. 11, which is a diagram showing current flow rate characteristics, is an operation explanatory diagram. FIG. 12 is a block diagram for detecting the displacement of the needle valve of the fuel injection nozzle, FIGS. 13 and 14 are explanatory diagrams of the same operation, and FIG. 15 is a diagram showing the displacement detection circuit of the needle valve. 10.25.39... Giant magnetostrictive alloy (giant magnetostrictive material), 11
．． 26.40... Electromagnetic coil, 22... Needle valve, 13
．． 14... Thermocouple (temperature detection means), 15... Correction means, 27.43... Temperature sensor.

Claims (3)

[Claims] (1) Temperature detection means that includes an electromagnetic coil that generates a magnetic field and a giant magnetostrictive body that expands and contracts with changes in the magnetic field generated by the electromagnetic coil, and that detects the temperature near the giant magnetostrictive body; An electrostrictive actuator comprising: a correction means for correcting the amount of current flowing through the electromagnetic coil in accordance with a change in temperature near the giant magnetostrictive body detected by the electrostrictive actuator. (2) The electrostrictive actuator according to claim (1), wherein the giant magnetostrictive body operates a needle valve of a fuel injection nozzle. (3) The electrostrictive actuator according to claim (1), wherein the temperature detection means detects the temperature of the fuel supplied to the fuel injection nozzle.