JPH0775136B2 - 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. 6, 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 the 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, the adjustment point is the first spring 4
Also, the second spring 10, the screw 7, and the switching stroke adjusting screw 14 of the switch 3 and the four parts are extended, and there is a risk that it takes time to perform the adjusting work. In view of the above problems, the present invention provides a thermostat which is easy to assemble, easy to adjust and inexpensive, and has a mechanism for forcibly opening an auxiliary circuit such as an electric circuit for a heater. Is.

Means for Solving the Problems In order to solve the above problems, the thermostat of the present invention includes a first lever that abuts a pressure responsive element and opens and closes a switch by its rotation, and is rotatably attached to a device frame. Cam arm, a bias spring attached between the first lever and the cam arm, and a first leaf spring having one end fixed to the cam arm and the other end in contact with the outer peripheral surface of the cam, and the cam arm tip portion, The stopper portion of the device frame does not contact immediately before the snap switch turns off, but contacts immediately before the snap switch turns on, and contacts the shaft of the cam and the disc portion of the shaft. A second lever rotatably attached to the device frame; a spring having one end fixed to the second lever and the other end fixed to the device frame; and a terminal fixed to a resin case. And,
One end is fixed to the terminal, and the other end has an insulator,
A second leaf spring having a fixed movable contact and a movable contact fixed thereto is provided. On the other hand, an arm is provided at the second lever, and the arm is arranged so as to come into contact with the insulator at a constant movement position of the arm. The electric circuit is forcibly opened by the rotation of the shaft.

Action The present invention has the above-described configuration, and immediately before the switch is turned off, the tip of the cam arm does not come into contact with the device frame stopper and is turned off.
The force to turn on is determined by the first leaf spring force displaced by the cam and the bias spring force. The force to turn on is the force of the first leaf spring displaced by the cam because the tip of the cam arm contacts the stopper immediately before turning on. Regardless of the constant force, a constant temperature reset type thermostat is formed, and the rotation of the shaft moves the arm provided on the second lever to move the second leaf spring fixed with an insulator to the fixed contact and the movable contact. The auxiliary circuit can be forcibly opened by moving it in the direction away from.

Embodiments An embodiment of the present invention will be described below with reference to FIGS. 1, 2, 3, and 4.
Description will be given with reference to the drawings. Reference numeral 20 denotes a pressure responsive element (gas bellows in the present embodiment, hereinafter referred to as bellows) in which gas is enclosed, and is a temperature detecting capillary 21 of the control unit.
Detects temperature changes. The bellows 20 is attached by soldering to a housing 23 fixed to a vessel frame 22 forming a thermostat outer shell. Further, a point piece 26 is fixed to the tip of the bellows, which comes into contact with a lever 25 mounted rotatably around a fulcrum 24 provided on a side wall 22 'of the vessel frame 22.

The first lever 25 has a head that abuts against the point piece 26 and a foot that engages with a fulcrum 24 provided on the device frame 22, and is made of an insulating material for opening and closing the snap switch. The spacer 27 is snap-fitted. Furthermore, on the opposite side that contacts the point piece 26,
It is bent in 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 has an adjusting screw as described above.
A cam arm which is attached to the first lever 25 via 29 and has the other end rotatably inserted into a fulcrum hole of the side wall 22 'of the device frame 22.
Mounted on 30. The cam arm 30 has two legs for the fulcrum.
The first plate spring 33 is provided with a space 31 through which the bias spring 28 can pass. Further, the protrusion 32 on the top of the cam arm 30 is
It is slidably incorporated into an elongated hole-shaped stopper 35 provided on the top wall 34 of the device frame 22. Further, the first plate spring 33 has one end fixed to the cam arm 30 and the other end fixed to the top wall of the device frame 22 as described above.
Fixed to a shaft 36 rotatably attached to 34,
It comes into contact with the cam 37 whose outer peripheral dimension has changed. The second lever 38, which is in contact with the disk portion of the shaft 36, has one end rotatably attached to the top wall 34 and has an arm 39, and the other end fixed to the device frame 22. It is connected to the spring 40.

Further, the snap switch 41 and the terminal 42 are held by a resin case 43, and the case 43 is fixed to the device frame 22. Further, the switching stroke of the snap switch 41 is adjusted by the adjusting screw 44 screwed into the case 43.

The second leaf spring 45, one end of which is fixed to the terminal 42,
An insulator 46 is provided at the other end, and a fixed contact 47 and a movable contact 48 for opening and closing are fixed.

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

Detects the temperature change of the control unit, for example, snap switch
Consider the case where 41 turns off. The output of the bellows 20 changes depending on the temperature of the control unit, and the snap switch can be used at any temperature.
Make 41 cut. The force for moving the first lever 25 in the OFF direction is the force F _B of the bias spring 28 and the first leaf spring.
33 force F _L is implicated in the case of F _B <F _L, cam arm 30 does not abut the stopper 35 of the vessel frame 22, a floating state. Here, in order to turn off the snap switch 41 at an arbitrary temperature, the force of the bias spring 28 may be adjusted by the adjusting screw 29 within a range that does not break the relationship of F _B <F _L. Further, the displacement of the cam 37 caused by the rotation of the shaft 36 causes the force of the first leaf spring 33 to change within a range satisfying the relationship of F _B <F _L , resulting in a change in the OFF temperature.

Next, consider the case of turning on. The force for moving the first lever 25 in the ON direction can be varied by adjusting the switching stroke of the snap switch 41 by adjusting the adjusting screw 44.

When the switching stroke is increased, the first lever 25 has to move to turn on the snap switch 41, 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 and
The change in the spring force of the first leaf spring 33 due to the rotation of 36 can be ignored,
As a result, the force to turn on, that is, the temperature, is
It is constant regardless of the position of.

As shown in FIG. 5, depending on the position of the shaft 36, a constant temperature, reset type thermostat in which the OFF temperature can be varied and the ON temperature is constant is formed. Finally, consider the case where the electric circuit is forced to open.

By rotating the shaft 36 in the counterclockwise direction, the protrusion of the second lever 38 comes into contact with the stepped portion of the disc portion of the shaft 36, and the force of the spring 40 is changed. An arm provided on the second lever 38 that moves as shown in FIG.
39 is moved in the direction of arrow A in FIG. 4, the second leaf spring 45 having the insulator 46 is moved in the direction of arrow B in FIG. 4, and the movable contact 48 fixed to the second leaf spring 45 is moved. It is forcibly separated from the fixed contact 47 that was in contact.

As described above, the first plate spring 33, which is indispensable for producing the constant temperature return characteristic, is simply fixed to the cam arm 30,
Easy to assemble, and the adjustment point is bias spring
The adjustment screw 29 for adjustment and the adjustment screw 44 for adjusting the switching stroke of the snap switch 41 are required only at two places, and it does not take time to adjust. In addition, the auxiliary circuit such as the heater contact can be forcibly opened simply by rotating the shaft 36 without using a separate component such as a micro switch.

EFFECTS OF THE INVENTION As described above, according to the present invention, the first lever that comes into contact with the pressure responsive element and opens and closes the snap switch by its rotation, the cam arm rotatably attached to the device frame, the first lever and the cam arm. It consists of a bias spring mounted between the two, 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 snap switch does not come into contact immediately before turning on, and the snap switch comes into contact immediately before turning on, and also comes into contact with the shaft of the cam and the disc portion of the shaft, and the snap switch is rotatably attached to the device frame. 2 levers, one end, a spring fixed to the second lever and the other end fixed to the vessel frame, a terminal fixed to a resin case, and one end fixed to the terminal and insulated to the other end A second leaf spring having a movable contact fixed to the fixed contact and having a fixed arm, and an arm provided on the second lever so that the arm can contact the insulator at a constant movement position of the arm; Since the auxiliary circuit is configured to be forcedly opened by the rotation, there are four adjustment points in the conventional thermostat, and it takes time to adjust, but in the present invention, the force of the bias spring is used. The adjustment screw for adjusting and the adjustment screw for adjusting the switching stroke of the snap switch can be easily adjusted by adjusting only two positions.

2 By rotating the shaft without using a separate part such as a micro switch, it is possible to easily forcefully open the auxiliary circuit such as the contact for the heater.

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 an essential part of the thermostat, FIG. 3 is a view taken in the direction of arrow A in FIG. 1, and FIG. View B, fifth
FIG. 6 is a characteristic diagram of a constant temperature reset type thermostat, and FIG. 6 is a sectional view of a conventional thermostat. 20 …… Pressure response element, 22 …… Device frame, 25 …… First lever,
28 …… Bias spring, 30 …… Cam arm, 33 …… First leaf spring, 35 …… Stopper, 36 …… Shaft, 37 …… Cam,
38 …… second lever, 39 …… arm, 40 …… spring,
41 …… Switch, 42 …… Terminal, 43 …… Case, 45
...... Second leaf spring, 46 …… Insulator, 47 …… Fixed contact, 48 ……
… Movable contacts.

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 first lever, a switch that opens and closes by rotation of the first lever, and one end of the first lever that is adjustable, and the other end of which is attached to a cam arm that is rotatable around a device frame as a fulcrum. A spring, a first plate spring having one end fixed to the cam arm and the other end abutting the outer peripheral surface of a cam rotatably attached to the device frame, and a stopper provided with the tip of the cam arm on the device frame. Inserted in the
Immediately before the switch is turned off, the cam arm tip and the device frame stopper are not in contact with each other, and immediately before the switch is turned on, the cam arm tip and the device frame stopper are in contact with each other. And a second lever rotatably attached to the device frame, one end fixed to the second lever and the other end fixed to the device frame, and a resin case And a second leaf spring having one end fixed to the terminal and an insulator at the other end, to which a movable contact that abuts the fixed contact is fixed, on the other hand, an arm is provided on the second lever, A thermostat, wherein the arm is arranged so as to be able to contact the insulator at a constant movement position, and the auxiliary circuit is forcibly opened by the rotation of the shaft.