JPH0775135B2 - Thermostat - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a thermostat for controlling the temperature of an electric refrigerator, a freezer, a showcase, etc. More specifically, the OFF temperature changes even when the temperature control dial is rotated, but the ON temperature Relates to a constant temperature reset type thermostat.

2. Description of the Related Art As a conventional technique, there is an example disclosed in Japanese Utility Model Laid-Open No. 54-45979. As shown in FIG. 4, reference numeral 1 is a bellows which causes a pressure change depending on temperature, 2 is a lever which comes into contact with the bellows 1 and is rotatable, and 3 is a switch which is opened and closed by rotation of the lever 2. The lever 2 has a bellows 1
Is biased by the first spring 4 in the opposite direction to the output of the. Further, there is an arm 8 rotatably attached to the device frame 5, one end of which engages with a stopper 6 of the device frame 5 and is joined to the lever 2 via an adjustable screw 7, and the device frame 5 Has a cam 9 rotatably attached to one end thereof, and one end thereof interlocks with the other end thereof, and a cam arm 11 to which a second spring 10 is attached, and the second spring 10 is engaged with the arm 8. It is a composition.

Here, when the temperature rises and the bellows 1 expands, the lever 2 rotates counterclockwise, turning on the switch 3 against the biasing force of the first spring 4. Here, the force of the second spring 10 does not move from the position where the arm 8 is the stopper 6 of the device frame 5, so the screw 7 should be adjusted so as not to contact the lever 2 at the ON position. If cam 9
Regardless of the position of, the ON temperature is constant because it is governed only by the first spring 4. Conversely, when the temperature drops, the bellows 1 contracts, the lever 2 rotates clockwise, and the switch 3 is turned off. At this time, the lever 2 must come into contact with the screw 7 before the OFF position, and the switch 3 must be turned OFF against the biasing force of the second spring 10 via the arm 8. Here, since the contact surface of the cam arm 11 on the cam bottom surface 12 is displaced by the rotational position and the cam arm 11 is displaced together with the cam 9, when the dial is turned to rotate the cam 9, the cam arm 11 is also displaced in association with the second cam. The tension of the spring 10 also changes. Therefore, the spring force applied to the lever 2 also changed, and as a result, it was possible to adjust the OFF temperature.

Problems to be Solved by the Invention In the prior art, since the first spring 4 and the second spring 10 are both tension coil springs, the lever 2 during assembly is
The hook part of the spring must be manually assembled to the arm or arm 8, and the end of the spring opposite to the hook part must be inserted with something like a nut and then adjusted with the adjusting screw 13. However, there is a problem in that it is difficult to assemble automatically, which may lead to an increase in cost.

Further, the adjustment points also extend to the first spring 4, the second spring 10, the screw 7, and the switching stroke adjusting screw 14 of the switch 3 and four places, and there is a risk that the adjustment work will be troublesome.

In view of the above problems, the present invention provides a thermostat that is easy to assemble, easy to adjust, and inexpensive.

Means for Solving the Problems In order to solve the above problems, a thermostat according to the present invention is attached to a pressure responsive element, a lever for opening and closing a switch by its rotation, and a rotatably attached to a device frame. A cam arm, a bias spring attached between the lever and the cam arm, a plate spring having one end fixed to the cam arm and the other end abutting the outer peripheral surface of the cam, and further the cam arm tip portion and the stopper portion of the device frame. However, the snap switch does not come into contact immediately before it is turned off, but comes into contact immediately before the snap switch is turned on.

Action According to the present invention, the cam arm tip does not come into contact with the device frame stopper immediately before the switch is turned off, and the force to turn off is determined by the leaf spring force displaced by the cam and the bias spring force, and immediately before turning on. Since the tip of the cam arm contacts the stopper, the force that turns on becomes a constant force regardless of the force of the leaf spring displaced by the cam, and a constant temperature reset type thermostat is formed.

EXAMPLE An example of the present invention will be described below with reference to FIGS. 1 and 2. Reference numeral 20 denotes a pressure responsive element (a bellows, hereinafter referred to as a bellows) in which gas is enclosed, and a temperature detecting capillary 21 of a control unit detects a temperature change. The bellows 20 is attached by soldering to a housing 23 fixed to a vessel frame 22 forming a thermostat outer shell. Further, at the tip of the bellows, a lever mounted so as to be rotatable around a fulcrum 24 provided on the side wall 22 'of the device frame 22.
A point piece 26 that abuts 25 is fixed.

The lever 25 has a head that abuts the point piece 26 and a foot that engages with a fulcrum 24 provided on the device frame 22, and a spacer made of an insulating material for opening and closing the snap switch. 27 is a snap fit. Further, the opposite side of contact with the point piece 26 is bent into a substantially U shape, and has a hole to which an adjusting screw 29 for adjusting the spring force of the bias spring 28 is attached. One end of the bias spring 28 is attached to the lever 25 via the adjusting screw 29 as described above, and the other end is attached to the cam arm 30 rotatably inserted into the fulcrum hole of the side wall 22 'of the device frame 22. The cam arm 30 has two legs 31 for fulcrums, a projection 32 at the top, and a leaf spring 33 having a space through which the bias spring 28 can pass. Further, the protruding portion 32 on the top of the cam arm 30 is slidably incorporated in a long hole-shaped stopper 35 provided on the top wall 34 of the device frame 22. Further, the leaf spring 33 has a cam arm at one end as described above.
The cam portion of the cam shaft 39, which is fixed to 30, the other end of which is rotatably attached to the top wall 34 of the device frame 22 by a fit spring 36, and which has a cam portion 37 and a shaft portion 38 of varying outer circumference
Abut 37.

Further, the snap switch 40 is held by a resin case 41, and the case 41 is fixed to the device frame 22.
The switching stroke of the snap switch 40 is
It is adjusted by the diff screw 42 screwed into.

The operation of the thermostat configured as above will be described.

Detect the temperature change of the control unit, for example snap switch 40
Consider the case when is turned off. Bellows 2 depending on the temperature of the control unit
The output of 0 changes and the snap switch 40 is turned off at any temperature. The force to move the lever 25 in the OFF direction is related to the force F _B of the bias spring 28 and the force F _L of the leaf spring 33. When F _B <F _L , the cam arm 30 acts as the stopper 35 of the device frame 22. Does not come into contact with each other and is in a floating state. Here, in order to turn off the snap switch 40 at an arbitrary temperature, the force of the bias spring 28 may be adjusted with the adjusting screw 29 within a range that does not break the relationship of F _B <F _L. Further, the rotation of the cam shaft 39 causes the displacement of the cam portion 37, so that the force of the leaf spring 33 is F _B <F _L.
The OFF temperature changes as a result because it changes within the range that satisfies the relationship of. Next, consider the case of turning on. Turn on lever 25
The force for moving the snap switch 40 can be varied by adjusting the switching stroke of the snap switch 40 by adjusting the diff screw 42.

When the switching stroke is increased, the lever 25 has to move to turn on the snap switch 40, and as a result, the force F _B of the bias spring 28 increases and F _B > F _L.

At this time, the cam arm 30 contacts the stopper 35 of the device frame 22,
The change in the spring force of the leaf spring 33 due to the rotation of the camshaft 39 is
It can be ignored, and as a result, the force for turning on, that is, the temperature is constant regardless of the position of the camshaft 39.

As shown in FIG. 3, depending on the position of the camshaft 39, OF
A constant temperature reset type thermostat with variable F temperature and constant ON temperature is formed.

As described above, the coil spring is the bias spring 28
Since the leaf spring 33 is only fixed to the cam arm 30, it is easy to assemble and can be automatically assembled, and the adjustment points are for adjusting the adjustment stroke of the adjusting screw 29 and the snap switch 40 for adjusting the bias spring 28. The diff screw 42 only needs to be installed in two places, and it does not take time to adjust.

EFFECTS OF THE INVENTION As described above, according to the present invention, a lever that contacts a pressure responsive element and opens and closes a snap switch by its rotation, and a cam arm that is rotatably mounted on a device frame, and is mounted between the lever and the cam arm. A bias spring and a leaf spring with one end fixed to the cam arm and the other end in contact with the cam outer peripheral surface.The tip of the cam arm and the stopper provided on the device frame contact immediately before the snap switch turns off. Since it is configured so as to make contact immediately before the snap switch is turned on, 1) Like a conventional thermostat, the coil spring can be easily assembled without taking time, and the cost can be reduced.

2) There were four adjustment points in the conventional thermostat and it took time to adjust, but in the invention product, there are two places, the adjustment screw for adjusting the force of the bias spring and the diff screw for adjusting the switching stroke of the snap switch. The adjustment can be done easily and easily.

As described above, it is very useful in practice.

[Brief description of drawings]

FIG. 1 is a sectional view of a thermostat showing an embodiment of the present invention, FIG. 2 is a perspective view of a main part of the thermostat, FIG. 3 is a characteristic diagram of a constant temperature reset type thermostat, and FIG. 4 is a conventional thermostat. FIG. 20 …… pressure response element, 22 …… device frame, 25 …… lever, 30…
… Cam arm, 28 …… Bias spring, 37 …… Cam circumference,
33 …… leaf spring, 35 …… stopper, 40 …… switch.

Claims (1)

[Claims] 1. A pressure responsive element enclosing a gas that causes a pressure change due to a temperature change of a control unit and a part of an instrument frame that abuts on the pressure responsive element and forms an outer shell of a thermostat can be rotated about a fulcrum. A lever, a switch that opens and closes by rotation of the lever, a bias spring that is attached to the lever so that one end is adjustable, and the other end is attached to a cam arm that is rotatable around a device frame as a fulcrum, and one end of the cam arm. Is fixed, and the other end is in contact with the outer peripheral surface of the cam rotatably attached to the equipment frame, and the tip of the cam arm is inserted into the stopper provided on the equipment frame. The thermostat is characterized in that the tip is not in contact with the device frame stopper, and the cam arm tip is in contact with the device frame stopper immediately before the switch is turned on.