JPH021606Y2 - - Google Patents

Description

[Detailed description of the invention] [Field of industrial application] The present invention relates to a temperature control device for electric mats.
In particular, the present invention relates to a device capable of selectively operating and controlling the temperature of a plurality of heating elements arranged separately in a mat.

[Conventional technology]

For electric mats equipped with a current-carrying heating element, it would be convenient and reduce running costs if only the used surface of the mat could be partially heated, as opposed to the entire surface heating operation such as when starting electricity or during rapid heating. It is economical and can be reduced.

Therefore, a configuration is adopted in which a single mat is composed of a plurality of independent heating elements, and each of these heating elements is energized selectively or simultaneously.

[The problem that the idea attempts to solve]

By the way, this type of electric mat requires temperature control when it is energized, and for this purpose a sensing element is placed at a temperature sensing position within the mat, and the energization to the heating element is controlled based on the sensing signal of the element. Measures will be taken. However, when multiple heating elements are arranged in a mat, it is necessary to detect only the state of the heating element while it is being energized, so a detection element suitable for each heating element used independently must be installed. Moreover, a unique temperature regulating device configuration is required, such as having to operate these individual sensing elements under the same conditions, for example, under a set constant regulating temperature.

Therefore, the present invention is a temperature control device comprising a plurality of such heating elements and corresponding temperature-sensitive sensing elements, which enables selective use of the heating elements, and has a stable temperature control function. The purpose is to develop a device that demonstrates this.

[Means to solve the problem]

According to the present invention, the purpose is to selectively connect a plurality of electric heating elements in a power supply circuit that is regulated by a zero-volt switch circuit composed of thyristors and the like and to connect them in parallel. , and each temperature-sensitive thyristor placed close to each heating element is connected in parallel to the thyristor control signal circuit of the zero-volt switch circuit, and each gate circuit of these temperature-sensitive thyristors is connected to the This is achieved by a temperature control device in an electric mat configured to selectively insert one variable resistor for temperature adjustment by operating a switch in conjunction with a changeover switch.

[Effect]

The changeover switch in the power supply circuit functions to connect each of the plurality of divided electric heating elements to the power supply circuit individually or in parallel by selectively switching the switch.

This power supply circuit is controlled by a zero volt switch which is activated when the phase of the commercial alternating current power supply voltage reverses and starts energizing the connected heating element.

Therefore, the electric heating element selected by the changeover switch is determined to continue being energized every half cycle of the commercial AC power supply, and continues to receive power and generate heat.

On the other hand, a temperature-adjusting variable resistor is circuit-connected to the temperature-sensitive thyristor placed close to the heating element that is energized by the selection, in conjunction with the selection of the heating element. Therefore, when the temperature-sensitive thyristor detects the set temperature in the temperature adjustment variable resistor, it operates and prevents the zero-volt switch from switching to the conductive state or maintaining the conductive state. It is possible to control the temperature of the heating element during power receiving operation.

Moreover, one temperature-adjusting variable resistor is connected to one of the temperature-sensitive thyristors corresponding to the heating element in operation, so all the heating elements in operation are connected to this one resistor. It operates according to the set temperature.

Note that other temperature-sensitive thyristors that are not connected to the resistor and are not directly involved in temperature regulation operate in a higher temperature range that is not regulated by the resistor, so they are considered elements for preventing excessive temperature rise. functions as

〔Example〕

The following is a detailed description based on the illustrated embodiment. The figure is a circuit diagram showing an embodiment of the device of the present invention, in which a commercial AC power source is input, and the power switch is selectively switched to one side via the power switch 1 and the changeover switch 2. Alternatively, a power supply circuit is constructed in which two energizing heating elements 3a and 3b, which are connected in parallel at the same time, and a bidirectional control rectifier 4 (hereinafter referred to as TRIACK) are connected in series. The changeover switch 2 has a configuration of 4 circuits and 3 contacts, and the movable contact pieces 2a and 2b are the contacts.
When switched to the side in contact with P ₁ and P ₂ , only the heating element 3a is inserted in series into the power supply circuit, and on the other hand, with the contacts P ₃ and P ₄ in contact at the solid line positions shown in the figure,
The heating elements 3a and 3b are inserted into a circuit together in parallel with each other, and only the heating element 3b is inserted in series into the circuit at a downward movement position shown in the figure where it comes into contact with contacts _P5 and _P6 . be.

On the other hand, the gates of the triac 4 are silicon controlled rectifiers (hereinafter referred to as SCRs) connected in opposite directions.
) 5 and 6 to one pole side of a trigger capacitor 7 connected to a power supply. Further, a diode 8 is connected in parallel to the SCR 5 in a reverse direction. Furthermore, the gate of the SCR 5 is connected to the anode side end of a trigger capacitor 10 connected in series with a diode 9, and the gate of the SCR 5 is
6 gate to diode 11 and capacitor 12
A DC bias circuit consisting of a capacitor 13, a bleeder resistor 14, and a Zener diode 15 are connected to a gate circuit. The configuration of these SCRs 5 and 6 and their gate circuits is a static switch circuit configuration for controlling the triac 4 to conduct at zero volts.

Then, an N-gate SCR is connected between the divided voltage output terminals of the bleeder circuit equipped with the DC bias circuit.
Temperature-sensitive switch elements 16a and 16b of the configuration are arranged in parallel connection with each other, and these elements 16a and 16b are connected in parallel to each other.
and 16b are connected to the anode sides of the elements 16a and 16b either directly or via a variable resistor 18 for temperature adjustment via another changeover switch 17 that is linked to the changeover switch 2. . That is, the changeover switch 17 has a four-circuit, three-contact configuration similar to the switch 2, and its movable contact pieces 17a and 17b are connected to the contacts _P7 to P12 _.
The movable contact pieces 2a and 2b are moved between the movable contact pieces 2a and 2b in synchronization with the movable contact pieces 2a and 2b.

In addition, reference numeral 19 designates a temperature-sensitive switch element of the same type as the temperature-sensitive switch elements 16a and 16b, which is made conductive at a constant temperature, for example, 70°C, by setting a resistor 20 in its gate circuit. This is a prevention circuit. In addition, the temperature-sensitive switch 19
Although one is shown in the figure, a plurality of them may be arranged distributed in the pine area as necessary. Further, 21 and 22 are fuses, 23 and 24 are display neon tubes, and other circuit elements not marked are capacitors, resistors, etc. necessary for stable operation of this circuit.

Next, to explain the operation of the device of the present invention having such a configuration, first, the changeover switches 2 and 1
When the power switch 1 is turned on with the SCR 6 placed at the position shown by the solid line, the SCR 6 receives a stable positive gate voltage from the bleeder circuit after the transition period of several cycles of commercial AC has passed since the power was turned on.
conducts at the beginning of the power supply voltage phase when negative pressure is applied to its cathode, and as a result, the triax 4 receives a negative gate current and becomes conductive, so the heating element 3
At the same time that a and 3b are energized, trigger capacitor 7 is charged through diode 8.

When the phase is reversed, the holding current of the triac 4 is cut off and it becomes non-conductive. However, in the opposite phase, the SCR 6 becomes non-conductive, while the other SCR
Since the capacitor 10 of the gate circuit 5 is charged with the current passing through the diode 9 during the previous phase, the positive voltage pushed up by this is received at the gate and the capacitor 10 becomes conductive.

As a result, the trigger capacitor 7 is also further reverse biased from the previous charging state, and as a result, the trigger capacitor 4 receives a sudden negative gate voltage from the capacitor 7 at the beginning of the opposite phase of the power supply voltage (at the time of voltage conversion). Conducts when receiving current (zero volt switch operation)
do.

Therefore, the heating elements 3a and 3b continue to be energized and generate heat.

The heat generating elements 3a and 3b are arranged inside the mat to constitute an electric mat, and at the same time, the temperature sensitive switch elements 16a and 16b are connected to the heat generating elements 3a and 3b.
Since the temperature of the mat surface, that is, the temperature of the temperature sensing position reaches the temperature adjusted by the resistance value setting of one temperature adjustment variable resistor 18 due to heat generation, , the temperature-sensitive switch element 16b conducts on one side of the power supply voltage phase in the solid line connection state shown in the figure. As a result, the bleeder circuit
The voltage drops during the conducting phase of b, and SCR6 is kept non-conducting in the same phase. Therefore, since the triac 4 is non-conductive and charging to the trigger capacitor 7 does not proceed, there is no reverse bias effect on the capacitor 7 during the opposite phase, and the triac 4 still maintains a non-conductive state. , the power to the heating elements 3a and 3b is cut off.

That is, the temperature sensitive switch elements 16a and 16
Of the elements 16b, the temperature is regulated by the variable resistor 18, and the other element 16b is normally maintained in an operating state at an excessively high temperature.

Therefore, when operating only one of the heating elements 3a and 3b, for example, by moving the switch 2 and 17 upward from the illustrated position, only the heating element 3a is connected to the circuit. At the same time, the gate circuit of the sensitive switch element 16a placed at the sensitive position of the heating element 3a is
By contacting the contact _P7 of the movable contact piece 17a, the variable resistor 18 is connected in series, and conduction occurs according to the mat temperature caused by the heating element 3a during heat generating operation, as in the case described above. Turn off the electricity that generates heat. Also, when only the heating element 3b is connected to the circuit by switching the changeover switches 2 and 17, the operation of the temperature-sensitive switch element 16b is the same as described above.

Then, the heating elements 3a and 3b are de-energized.
As the mat temperature decreases, the temperature-sensitive switch elements 16a and 16b operate with the bleeder output of the AC power supply voltage passing through the capacitor 13 (the DC bias current is set below the holding current of the elements 16a and 16b). ), the current conduction or discontinuity is determined depending on the phase of the half-wave of the alternating current power supply, so that it becomes nonconduction at a certain phase when the temperature drops. Therefore, the heating elements 3a and 3b that have been de-energized are again energized in the above operation.

[Effect of idea]

As described above, according to the device of the present invention, in response to selection switching of a plurality of heating elements, the temperature sensor placed at the temperature sensing position of at least one heating element among the heating elements that are energized is activated. Since the thyristor is placed under the control of the regulated temperature, and the operation of the thyristor controls the energization to all the heating elements in operation,
First, only one variable resistor is required for temperature adjustment, which not only reduces the number of parts compared to when multiple resistors are provided for each heating element, but also reduces the temperature setting value for each temperature-sensitive thyristor. There is no need to correct errors, and the temperature-sensitive thyristor, which is not involved in temperature control, can be used as an element to prevent excessive temperature rises, so it can be used as an element to prevent excessive temperature rises, which is the purpose of preventing excessive temperature rises, which are arranged in large numbers in various parts of electric mats. The device of the present invention is extremely effective in practice, as it is possible to reduce the number of elements.

[Brief explanation of drawings]

The drawing is a circuit diagram showing one embodiment of the device of the present invention. 2 and 17...changeover switch, 3a and 3b...
...Heating element, 4...Triack, 16a, 16b
and 19...temperature-sensitive switch element, 18...variable resistor for adjusting temperature.

Claims (1)

[Scope of utility model registration request] A plurality of electric heating elements are placed in a power supply circuit that is regulated by a zero-volt switch circuit composed of a thyristor, etc., via a changeover switch that selectively connects them in parallel, and each of the heating elements is Each temperature-sensitive thyristor arranged in close proximity is connected in parallel to the thyristor control signal circuit of the zero-volt switch circuit, and each gate circuit of these temperature-sensitive thyristors is operated by a switch that is linked to the changeover switch. A temperature control device for an electric mat configured to selectively insert one variable resistor for temperature adjustment.