JP2551073Y2 - thermostat - Google Patents

Description

[Detailed description of the invention]

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thermostat, and more particularly, to a bimetal type thermostat having a bimetal disk which repeats a snap operation as the temperature rises and falls.

[0002]

2. Description of the Related Art For example, in the ordinary temperature control of an electric heater, as shown in FIG. 7, the first circuit repeatedly turns on and off the electric heat source by the first circuit so that the temperature falls within a desired range. (Normal control A). If the temperature rises excessively for some reason (when the temperature rises excessively), the second circuit detects an excessive temperature rise state and turns off the energization c (excessive rise prevention control B). In other words, 2
To perform various types of temperature control, a certain temperature correlation and a stable thermal response are required.

FIG. 8 shows a first conventional example for performing the above-described temperature control, and FIG. 9 is a circuit diagram thereof. That is, as can be seen from FIG. 9, the power supply PW is connected to the power supply PW via the switch SW.
An electric heat source (heater) a, a first circuit (thermostat) b, and a second circuit (thermal fuse) d are connected in series. The thermostat b and the thermal fuse d are connected by a wiring member c.

A part of the circuit shown in FIG. 9 is shown in FIG.
That is, a thermostat b and a temperature fuse d are provided on the heater a. Temperature fuse d is heater a
In order to electrically insulate it from the heater a, it is provided in a hollow state or via a ceramic pipe e for reducing the thermal time constant at all. Wiring tool c is U
It is bent in the shape of a letter, and connects the thermostat b and the thermal fuse d.

FIG. 10 shows a second conventional example, and FIG. 11 is a circuit diagram thereof. 10 and 11 are different from the examples of FIGS. 8 and 9 in that an overheat prevention thermostat f is used in place of the temperature fuse d. Other points are the same as those in the examples of FIGS.

In FIGS. 8 and 10, a faston receptacle g is used to connect the lines.

[0007]

In FIG. 8, the thermal fuse d is not directly on the heat sensing surface on the heater a but is floated in the air or provided via a ceramic pipe e. That is, the thermal fuse d cannot be provided directly on the heater a, but must be floated from the heat sensing surface of the heater a by some means. Therefore, the sensing accuracy of the thermal fuse d is inevitably inferior to that of the direct sensing type thermostat provided directly on the heat sensing surface. That is, there may be a problem that the thermal fuse is blown before the heater reaches a desired temperature (early blow), the fuse does not blow even when the temperature reaches the desired temperature, and is cut off at a temperature higher than that (slow blow). Not a few. For this reason, it is not suitable for preventing a rapid heating type heater, such as a ceramic heater, which has been frequently used in recent years, from being excessively heated.

As can be seen from FIGS. 8 and 10, the wiring c is connected between the thermal fuse d and the thermostat b and between the overheat prevention thermostat f and the thermostat b. At least one end of the wiring c is a faston receptacle. In order to make the connection by the wiring c reasonable, it is necessary to keep a certain distance between the two temperature sensing elements, that is, between the temperature fuse d and the thermostat b and between the overheat prevention thermostat f and the thermostat b. There is. In order to ensure sufficient insulation and secure a reasonable wiring space, it is desirable to separate the two temperature-sensitive elements by at least 40 mm or more, for example.
If the two temperature-sensitive elements are separated to some extent in this way, especially in recent miniaturized electric heating products, the heat sensing positions are greatly different. In other words, the two temperature sensing elements are provided at different points on the heat source and detect different temperatures.

[0009] The present invention has been made in view of the above,
It is an object of the present invention to provide a thermostat having a plurality of temperature sensing elements, wherein the temperature sensing elements are capable of sensing two portions at substantially the same temperature in close proximity to a temperature sensing object.

[0010]

The thermostat of the present invention is housed in the same case and includes a plurality of thermostat sections which operate independently to turn on / off respective switches, and each thermostat section is provided with a thermostat. It has a bimetal disk that has the same time constant, changes from the first state to the second state by performing a snap operation when a temperature change is detected, and switches on and off the switch, and furthermore, the thermosensitive surfaces of the thermostat parts are the same. It is configured as being formed on a plane.

[0011]

Each thermostat has a bimetal disk having the same thermal time constant. Further, the heat-sensitive surfaces for these bimetal disks are formed on the same plane. Therefore, heat from the subject is transmitted to each thermostat in the same manner. Thus, each bimetal disk has an equal thermal time constant. For this reason, each bimetal disk performs a snap operation when a predetermined operating temperature is reached according to a rise in the temperature of the subject, and switches the respective switches on and off.

[0012]

1, 2 and 3 show a thermostat 1 as an embodiment of the present invention, and FIG. 2 is a plan view thereof.
2A and 2B are cross-sectional views taken along line II of FIG. 2, and FIG. 3 is a bottom view. FIGS. 1A and 1B show a bimetal disk 5a,
This is for explaining before and after the snap operation (reversal) of 5b.

The thermostat 1 has first and second terminals 1
0a, 10b and a common terminal 14 are provided. At a low temperature, between the terminals 10a and 14 in the first thermostat portion 17a and the second thermostat portion 17b
Are electrically connected between the terminals 14 and 10b. As the temperature rises, first, the terminals 10a and 14 are cut off, and then the terminals 14 and 10b are cut off. Also, terminal 10
As for the area between a and 10b, conduction occurs at a low temperature and shuts off at a high temperature. Therefore, this thermostat can be used as any of three-terminal control (control between terminals 10a and 14 and between terminals 14 and 10b) and two-terminal control (control between terminals 10a and 10b). In the case of two-terminal control, the common terminal 14 can be omitted.

More specifically, in FIGS. 1 (a) and 1 (b), reference numeral 3 denotes a case made of an insulating material, which has a substantially cylindrical shape as can be seen from FIG. 2, and has an upper side closed as can be seen from FIG. The lower side is open. The terminals 10a and 10b are fixed to the case 3 by caulking the upper ends of the support plates 9a and 9b having a substantially L-shaped cross section. The common terminal 14 is fixed to the case 3 by driving a rivet 15 into the upper end of the fixed contact plate support plate 13.

A movable contact 7 is provided on the support plates 9a and 9b.
movable contact plates 8a, 8b as leaf springs having a, 7b
Are fixed integrally. These movable contacts 7a, 7b
Are fixed contacts 11 provided on the fixed point contact plate 12
a and 11b are vertically opposed. Movable contacts 7a, 7b
Performs contact and separation operations with the movable contacts 11a and 11b. This operation is performed by the movable contact plates 8a and 8b.
Of the movable contacts 7a and 7b, and the force of the bimetal disks 5a and 5b coming into contact with the above-mentioned biasing force due to inversion. That is, a bimetal base 4 is fitted into the lower end of the case 3, and a cover 2 made of a heat-sensitive material is fixed to the lower end of the bimetal base 4. Between the inner surface of the cover 2 and the lower end surface of the bimetal base 4, bimetal disks 5a and 5b are housed so as to be alternately reversible between a first state in FIG. 1A and a second state in FIG. Have been. As the bimetal disk 5a, a disk (low-temperature heat-sensitive bimetal) that automatically repeats inversion (snap operation) for performing normal control is used.
As b, a material that reverses when the temperature is abnormally raised and automatically recovers when the temperature is lowered (high-temperature heat-sensitive bimetal) is used. Further, the thermal time constants of these bimetal disks 5a, 5b are assumed to be equal. These bimetal disks 5a, 5a
Above b, push-up bars 6a and 6b are provided slidably up and down with respect to the bimetal base 4. And FIG.
In the first state of (a), the movable contacts 7a, 7b are driven by the fixed contacts 11a, 1b by the urging force of the movable contact plates 8a, 8b.
1b. In the second state shown in FIG. 1B, the push-up bars 6a, 6b are moved by the bimetal disks 5a, 5b.
Moves upward to push up the movable contact plates 8a and 8b, whereby the movable contacts 7a and 7b are separated from the fixed contacts 8a and 8b. The bimetal disks 5a and 5b take the first state of FIG. 1A at a low temperature and the second state of FIG.
State, and automatically returns to the first state (a) as the temperature drops. As can be seen from FIG. 3, the bottom surface of the cover 2 has a reference surface portion 2a and a heat-sensitive surface portion 2 projecting downward therefrom.
b, 2b.

Next, the operation of the thermostat having the above configuration will be described.

The thermostat 1 is mounted such that the heat-sensitive surfaces 2b, 2b of the cover 2 are in contact with a subject, for example, a heater. Initially, the thermostat part 17
Both a and 17b are in a non-operating state, that is, in a first state of FIG. Here, when the temperature of the subject rises, the bimetal disk 5a of the thermostat 17a is moved to the position shown in FIG.
Invert as shown in FIG. As a result, the push-up bar 6a rises to move the movable contact 7a upward via the movable contact plate 8a. Thereby, the movable contact 7a and the fixed contact 11a are separated. Thereafter, when the temperature of the heater or the like decreases, the bimetal disk 5 returns from the state shown in FIG. 1A to the state shown in FIG.
As a result, the movable contact 7a is urged by the movable contact plate 8a.
Abuts on the fixed contact 11a. Thus, the thermostat 17a repeats contact and separation between the two contacts 7a and 11a. When the temperature rises beyond the normal temperature range, the thermostat 17b changes from the state shown in FIG. 1A to the state shown in FIG. Further, the state returns to the state of FIG. 1A from the state of FIG. With such an operation, the contact of the two contacts 7b and 11b also occurs in the thermostat portion 17b,
Separation takes place.

2 and 3, the dimensions of the outer shape can be determined, for example, as follows.

D 1 = 31.8 ± 1 (mm) D 2 = 15 (mm) D 3 = 12.3 φ (mm) D 4 = 4 (MAX) (mm) D 5 = 16.6 ± 0.2 (mm) 5 and 5 are a front view and a circuit diagram showing a main part of an example of an actual use state of the thermostat 1, respectively.
As can be seen from FIG. 4, the thermostat 1 is mounted on the heater 20. 2 of cover 2 of thermostat 1
The two heat-sensitive surfaces 2b, 2b are on the same surface, and thus these heat-sensitive surfaces 2b, 2b are in contact with the same surface of the heater 20. Further, these heat-sensitive surfaces 2b, 2b, that is, the two thermostat portions 17a, 17b are formed at extremely close positions. Therefore, according to this thermostat, the temperatures at two very close points of the heater 20 can be separately detected by the different thermostat portions 17a and 17b. The thermostat section 17
a and 17b are connected to the heater 20 as shown in FIG. That is, the heater 20 is connected to the terminals 10a and 10b.
Are connected in series. In particular, as can be seen from FIG.
This circuit has three terminals 10a, 10b and 14. Therefore, as described above, there are two usages, three-terminal control and two-terminal control.

FIG. 6 is a sectional view of another embodiment of the present invention.

FIG. 6 shows two thermostat sections 18a, 1
8b shows a case where the device is configured as a manual return type. Other configurations are the same as those in FIG.

Further, one of the two thermostat sections may be of the automatic return type and the other may be of the manual return type.

Further, the number of thermostat sections may be three or more. In this case, it is obvious that all or an arbitrary number of thermostat units can be of the automatic return type, and the rest can be of the manual return type.

Further, the operating temperatures of the bimetal disks in the plurality of thermostat sections may be equal or different.

In the above-described embodiment having two thermostats, it can be used as follows.

A: Thermostat with automatic temperature adjustment thermostat and thermostat for automatic reset type overheat prevention b: Thermostat with thermostat for automatic reset type overheat prevention or thermostat for automatic temperature adjustment and thermostat for manual resetting c: Thermostat section provided with a manual reset type thermostat section and a manual reset type thermostat section When the above-mentioned manual reset type thermostat section is used, double safety measures can be taken.

In the case of using a conventional thermal fuse, it was necessary to replace the fuse after the fuse was blown. However, according to the above embodiment in which the fuse was replaced with a thermostat, there was no need for such replacement work. It can be used repeatedly, for example, 5000 times or more.

Further, since the two thermostats have the same thermal time constant, there is no need for complicated experiments and comparisons, stable temperature sensing is possible, and a highly reliable product can be manufactured at low cost. Can be provided by

Further, since a plurality of thermostats are incorporated in the same case and cover, the number of components can be reduced and the internal wiring can be simplified.

[0030]

According to the thermostat of the present invention, since the thermal time constants of the bimetal disks of each thermostat portion are made equal and each heat-sensitive surface is formed on the same plane, the temperature on the same surface of the subject can be reduced. A plurality of thermostats can accurately detect the temperature in a state where the temperature difference between them is small, whereby when each of the thermostats detects a predetermined temperature, each bimetal disk can be operated to switch on and off each switch. It is possible to provide a thermostat including a plurality of thermostat sections capable of detecting the temperature of a plurality of portions having the same temperature in the subject.

[Brief description of the drawings]

FIG. 1 is a sectional view of an embodiment of the present invention.

FIG. 2 is a plan view of one embodiment of the present invention.

FIG. 3 is a bottom view of the embodiment of the present invention;

FIG. 4 is a front view of one usage example of the embodiment.

FIG. 5 is a circuit diagram thereof.

FIG. 6 is a cross-sectional view of another embodiment of the present invention.

FIG. 7 is a diagram showing an example of temperature control.

FIG. 8 is a front view of a first conventional example.

FIG. 9 is a circuit diagram thereof.

FIG. 10 is a front view of a second conventional example.

FIG. 11 is a circuit diagram thereof.

[Explanation of symbols]

 Reference Signs List 1 thermostat 2 cover 2a reference surface 2b heat-sensitive surface 3 case 4 bimetal base 5a bimetal disk 5b bimetal disk 6a push-up bar 6b push-up bar 7a movable contact 7b movable contact 8a movable contact plate 8b movable contact plate 9a support plate 9b support plate 10a terminal 10a Terminal 11a Fixed contact 11b Fixed contact 12 Fixed contact plate 13 Rivets 14 Common terminal 17a Thermostat section 17b Thermostat section

Claims (1)

(57) [Scope of request for utility model registration] 1. A thermostat unit which is housed in the same case and operates independently to turn on and off respective switches, wherein each of said thermostat units has the same thermal time constant and snaps when a temperature change is detected. It has a bimetal disk that operates to change from the first state to the second state and switches the switch on and off, and the thermosensitive surfaces of the thermostat parts are formed on the same plane. And a thermostat.