JPH018679Y2 - - 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.

For example, an idle-up control system for idling the engine in conjunction with the air conditioner switch when starting a vehicle air conditioner applies negative pressure to the diaphragm chamber 4 of the actuator 3 by opening and closing a solenoid valve 2, as shown in FIG. is introduced to drive the push rod 5 to control the opening and closing of the throttle valve 6.

However, in such a negative pressure actuator, the presence of piping is essential, and air leakage from the piping and fluctuations in the negative pressure in the intake pipe, which is the source of negative pressure, can result in low operational reliability and responsiveness, and damage to parts. It has the disadvantages of a large number of points, poor productivity and poor installation.

It is also conceivable to use an electromagnetic actuator as the actuator, but this has the drawback that it would be extremely large in order to increase the operating stroke, and it would not be possible to actually increase the operating stroke.

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, a housing that accommodates the push rod so as to be able to reciprocate in its axial direction, and one end of which is latched to the housing. a first spring made of a shape memory alloy that can generate heat when energized and whose other end is locked to the push rod and urges the push rod to move forward in the axial direction; a second spring made of a conductive material, which is locked and whose other end is locked to the housing and biases the push rod in a direction to move back in the axial direction; and an energizing means for energizing the first spring. The second spring is characterized in that one end of the second spring is electrically insulated from the push rod and electrically connected to the end of the first spring on the push rod side, and the second spring forms part of the current supply means.

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 the springs or either spring at normal temperatures. When the idle up signal is applied to the current supply means, a current also flows through the first spring itself, heating it up and reaching the reverse transformation temperature, the first spring returns to the shape it memorized at 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. After such operation, when the idle up signal disappears, the first spring becomes low temperature.
It is returned to its original position by the second spring force.

In this way, the present invention applies electricity to a spring made of a shape memory alloy to heat it, and presses the push rod by the reverse transformation movement that occurs at this time, and does not require piping that is difficult to seal.
It has the advantage that it is highly reliable because a constant force is always obtained, and that a large stroke can be obtained. Furthermore, if the first spring is made of a bidirectional shape memory alloy, reverse transformation occurs at two different temperatures, so three-position control is also possible.

In the above position control device, the second spring is made of a conductive material, and one end of the second spring is electrically connected to the end of the first spring on the push rod side while being electrically insulated from the push rod. The second spring forms part of the energizing means. In this way, the second spring acts as a current conducting means between the fixed housing and the first spring that extends and contracts in the axial direction of the push rod. This simplifies the structure of the energizing means, improves durability, and suppresses an increase in the number of parts. Further, there is no difficulty in handling the position control device due to the second spring being part of the current supply means.

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 11 of the push rod 10, and first and second 2 springs 13 and 14,
It mainly consists of a conductive wire 15 for energizing the springs 13 and 14. Pushrod 10
is a rod-like member that reciprocally passes through the end cap 16 from within the housing 12, and is provided with a flange-shaped stopper 19 made of synthetic resin approximately at the center of the housing 12.

The housing 12 includes a cylindrical body 1 made of synthetic resin.
7 and an end cap 16 fixed to the end of the main body 17 by screws 18. Main body bottom 17
A is provided with a protrusion 20 having approximately the same diameter as the inner end 11 of the push rod.

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 housing bottom 17a and the push rod stopper 19. This first
The spring 13 is made of, for example, Ti-Ni (atomic ratio 50%-
50%) system memory alloy, generates heat when energized and returns to its original shape at approximately 60 degrees. In the illustrated embodiment, the push rod 1 is stretched at this temperature.
0 is pressed upward (in Fig. 2), but it can also be contracted when heated. In this case, the first spring 13 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 electrically insulated from the push rod 10. The upper surface of the stopper 19 and the end cap 16 are respectively locked.

The first spring 13 has both ends 13a and 13b.
is bent in the axial direction and fixed through corresponding holes in the stopper 19 and the bottom wall of the housing 12. The upper end 14a of the second spring 14 is similarly fixed through a corresponding hole in the upper wall of the housing 12. A ring-shaped metal retainer 22 with an edge is disposed at the upper end flange portion of the stopper 19 and also serves as a terminal for the second spring 14 . both springs 13,
14 are connected to each other by the bent end 13a passing through the inside of the stopper 19. A conductive wire 15 is connected to an end 14a of the second spring 14 on the side of the end cap 16, and the conductive wire 15 passes through the end cap 16 and the housing body 17, protrudes from the bottom surface of the housing 17a, and serves as a terminal 15a. Also, the first spring 1
A conductive wire 15 is also connected to the bottom end 13b of the housing 3, and this conductive wire serves as a terminal 15a projecting through the housing bottom 17a. Lead wires 21 are connected to these terminals 15a, allowing both springs 13, 14 to be energized.

Note that the recesses forming the exposed parts of the conductor 15 on the upper and lower parts of the housing 17 are filled with insulating resin (epoxy, etc.).
is filled with.

When the springs 13 and 14 are not energized and are kept 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 push rod 10 is held at the bottom of the housing. It is pressed by the protrusion 20 of 17a. At this time, when the springs 13 and 14 are energized via the lead wire 21 and the first spring 13 is heated to a temperature higher than the operating temperature, the first spring 13 is made of a shape memory alloy, so it remembers when the temperature is high. Returns to shape, ie, stretched state. 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.

[Brief explanation of drawings]

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...Conducting wire.

Claims (1)

[Scope of utility model registration request] A push rod, a housing that accommodates the push rod so as to be able to reciprocate in the axial direction, and a current supply that urges the push rod in the direction of moving the push rod forward in the axial direction. a first spring made of a heat-generating shape memory alloy, one end of which is engaged with the push rod so as to oppose the first spring, and the other end of which is engaged with the housing to move the push rod back in its axial direction; The second spring is made of a conductive material and is biased, and an energizing means for energizing the first spring.
A position control device characterized in that one end of the spring is electrically connected to the end of the first spring on the push rod side while being electrically insulated from the push rod, and the second spring forms part of the current supply means.