JPH018680Y2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a position control device, and more particularly to an actuator used to control throttle opening.

The idle up control system, which idles up the engine in conjunction with the air conditioner switch when starting the vehicle air conditioner, applies negative pressure to the diaphragm chamber 4 of the actuator 3 by opening and closing the solenoid valve 2, as shown in FIG. The push rod 5 is driven to control the opening and closing of the throttle valve 6.

However, such negative pressure actuators have low operational reliability due to air leaks in the piping and fluctuations in the negative pressure in the intake pipe, which is the negative pressure source, and have a large number of parts, resulting in poor productivity and installation. It has the following drawbacks.

It is also conceivable to use an electromagnetic actuator as the actuator, but this has the disadvantage that the operating stroke cannot be increased.

The purpose of the present invention is to overcome the above drawbacks, and the position control device according to the present invention is characterized by a push rod, which accommodates the push rod in a reciprocating manner, and has a heat radiating wall made of a heat conductive member inside. a housing made of a material with low thermal conductivity, and a coiled first spring made of a shape memory alloy that remembers its shape at high temperatures and whose one end is locked to the housing and the other end is locked to a push rod.
a second spring having one end latched to the push rod and the other end latched to the housing to oppose the first spring; and a second spring in contact with the inner periphery of the first spring at its central hole so as to heat the first spring. a cylindrical heat conductive member disposed near the first spring so as to surround it and forming a part of the heat radiating wall; and an electric heating element disposed within the housing so as to be able to conduct heat to the heat conductive member. The heating element is formed as a part of the heat radiating wall that surrounds the outer periphery of the first spring with an air gap in between.

In this device, a first spring and a second spring are provided in a space between the housing and the push rod, and the push rod is held in a predetermined position by either or both springs at normal temperatures. When the electric heating element is energized, the heating element and the heat conducting member heated through it reach a high temperature, and the first spring reaches a reverse transformation temperature (e.g.
When heated above 60°C, the first spring returns to the shape it memorized at the high temperature. Therefore, the first spring contracts or expands against the second spring to move the push rod and change the opening degree of the throttle valve. When the idle up signal disappears after such an operation, the electricity to the electric heating element is stopped, the first spring becomes low temperature, and returns to its original position by the force of the second spring.

In this way, the present invention heats a spring made of a shape memory alloy and displaces the push rod by the reverse transformation movement that occurs at this time.There is no need for piping that is difficult to seal, and a heating means (electric heating element) is not required. The heat conduction member (and heat conduction member) also has a small heat capacity, and the housing that houses it also has excellent heat insulation and can effectively heat the shape memory alloy spring, resulting in excellent thermal response and energy saving.
It has the advantage that it is highly reliable because a constant force is always obtained, and that a large stroke can be obtained.

An embodiment of the position control device of the present invention will be described below.

As shown in FIG. 2, the position control device according to the present invention includes a push rod 10, a housing 12 that accommodates the end of the push rod 10, and first and second springs provided between the push rod 10 and the housing 12. 13 and 14, and the first
Thermal conduction member 21 for heating the spring 13
and an electric heating element 15.

The push rod 10 is a rod-shaped member that reciprocates through the end cap 16 from within the housing 12, and is provided with a flange-shaped stopper 19 made of synthetic resin at approximately the center of the housing 12.

The housing 12 includes a cylindrical body 17 made of a material with low thermal conductivity, that is, synthetic resin;
It consists of an end cap 16 fixed to the upper end. A hollow protrusion 20 extending to the stopper 19 is provided on the bottom portion 17a of the main body, and the lower end of the push rod 10 slides up and down in the space within the protrusion 20.

Main body bottom 17a and push rod stopper 19
A first spring 13 made of a shape memory alloy is provided between the lower surface and the first spring 13, and the ends of the first spring 13 are respectively engaged with the bottom 21c of the heat conducting member 21 and the push rod stopper 19. . This first spring 13 is made of, for example, Ti-Ni (atomic ratio
50%-50%) type shape memory alloy, e.g.
It returns to its original shape at 60°, and in the illustrated embodiment,
Extend the push rod 10 upwards (in Figure 2)
Although it is designed to be compressed, it can also be contracted when heated. In this case, the first spring 1
3 is provided on the end cap 16 side. Various operating temperatures can be selected depending on the application.

On the other hand, a second spring 14 made of a normal material (not a shape memory alloy) is provided between the upper surface of the push rod stopper 19 and the end cap 16, and both ends of the second spring 14 are connected to the upper surface of the push rod stopper 19 and the end cap 16. Each is locked.

A double cylindrical heat conductive member 21 as shown is disposed within the housing body 17. As shown in FIG. This member 21 includes an outer cylindrical portion 21a that contacts the inner peripheral surface of the housing body 17, and a housing bottom portion 17a.
It consists of a bottom part 21c that comes into contact with the upper surface, and an inner cylindrical part 21b that comes into contact with the outer peripheral surface of the protrusion 20. A coil spring, that is, a first spring 13 is fitted and disposed in contact with the inner cylindrical portion 21b, and a cylindrical electric heating element 15 is provided in contact with the outer cylindrical portion 21a. There is. With this configuration, the electric heating element 15 transfers heat to the heat conducting member 21 and heats the first spring 13 by thermal radiation, and the heat conducting member 21 transfers the transferred heat to the bottom 21c.
The heat is transmitted to the inner cylindrical portion 21b and heats the first spring 13 (heat conduction and heat radiation) via these. It is preferable that the heat conductive member 21 is made of a good heat conductor such as copper or aluminum. This electric heating element 15 can be made of, for example, a thin nichrome wire wound into a coil.
It can be heated by applying electricity through 2.

The heating element 15 is not energized, and the first spring 1
3 is maintained below the operating temperature (approximately 60°C), the force of the second spring 14 is greater than the force of the first spring 13, and the force of the push rod 10 is greater than the force of the first spring 13.
The stopper 19 is located on the protrusion 2 of the housing bottom 17a.
Pressed to 0.

At this time, when the electric heating element 15 is energized through the lead wire 22 and generates heat, the first spring 13 is directly heated by this, and the first spring 13 is directly heated by the heat conducting member 21 that is transferred with heat by the heating element 15. It gets heated even when it's hot. When the first spring 13 is heated to a temperature higher than the operating temperature, the first spring 13 returns to the shape stored at high temperature, that is, the stretched state, since the first spring 13 is made of a shape memory alloy. Therefore, the push rod 10 is pressed upward against the second spring 14.

Also, this energization is stopped, and the first spring 13
Once cooled below operating temperature, the first spring 13 is compressed by the second spring 14 to the position shown so that the push rod 10 moves downwardly. In this way, the second spring 14 operates as a return spring.

As described above, in the position control device of the present invention, the shape memory alloy spring constituting the actuator, that is, the first spring, is disposed in a housing that has a heat radiation wall formed therein, and the first spring is inserted through the heat radiation wall. This structure heats the spring from the inside and outside. Further, the heating element of the present invention is configured to form a part of the heat radiation wall around the outside of the first spring to heat the wall. With this configuration, the first
The spring can be heated effectively, and as a result, it is possible to provide a position control device with excellent thermal response, energy saving properties, and high operational reliability.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram showing a conventional idle up system, and FIG. 2 is a side sectional view showing a position control device according to the present invention. 10...Push rod, 12...Housing, 13...First spring, 14...Second spring, 15...Electric heating element.

Claims (1)

[Scope of utility model registration request] A push rod, a housing which accommodates the push rod in a reciprocating manner and is made of a material having a low thermal conductivity and has a heat radiation wall made of a heat conductive member formed therein, one end of which is fixed to the housing and the other end of which is fixed to the push rod. a coiled first spring made of a shape memory alloy that remembers its shape at high temperatures; and a second spring that opposes the first spring and has one end locked to the push rod and the other end locked to the housing. and a cylindrical heat conductor that is in contact with the inner periphery of the first spring at the center hole thereof so as to heat the first spring, and that is disposed in the vicinity of the first spring so as to surround the first spring, and that forms a part of the heat radiating wall. and an electric heating element disposed in the housing so as to be able to transfer heat to the heat conducting member, the heating element being a part of the heat radiating wall surrounding the first spring with an air gap in between. A position control device consisting of a