JP3529166B2 - Heater load connection switching device - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heater load connection switching device, and more particularly to a device for switching between two heater loads of a heating device such as an electric carpet so as to use one of them in series, in parallel or one of them. It is about.

[0002]

2. Description of the Related Art Electric carpets have conventionally been designed so that the amount of heat generated can be adjusted for various purposes. For example, JP-A-6
Japanese Patent Laid-Open No. 3-181285 discloses that a plurality of heaters having different heat generating capacities are arranged on the same heat generating surface of an electric carpet, and a switching means for selectively switching these heaters is provided. Disclosed is an electric heating device configured to switch to a heater with a high heat generation capacity at the start of heating when the temperature of the surface is low and when the ON time of the heater becomes long during heating due to a decrease in outside air temperature. There is.

However, in the electric heating device described in the above publication, wiring is complicated because a plurality of heaters having different heat generation amounts are provided on the same heat generation surface, the number of parts increases, and the number of man-hours such as manufacturing control increases. There is a problem of doing.
Therefore, an electric carpet with a heating area of 2 tatami mats or more,
Conventionally, a heating surface is divided into two parts, and a heater having the same heating capacity is arranged on each heating surface.

In an electric carpet in which the heating surface is divided into two parts and heaters are respectively arranged, two heaters are connected in parallel at the start of heating, and when the temperature rises, a relay is operated to connect the heaters in series. Japanese Utility Model Laid-Open No. 3-89315 discloses an electric carpet in which the power consumption is reduced and the heater is turned on for a long time. However, in the circuit described in this publication, the series side pole of the serial / parallel switching relay is connected to one of the relays, so that the power supply is short-circuited unless the serial / parallel switching relay operates smoothly. There is.

In addition, as a means for controlling the amount of heat generation by connecting a plurality of heaters in series / parallel, for example, Japanese Utility Model Laid-Open No. 57-105510 discloses a temperature of an electric blanket or an electric carpet at the initial stage of energization. In order to accelerate the start-up, the same surface is arranged so as to be warmed by two resistance wires, and the resistance wires are connected in parallel at the initial stage of energization by a relay operated by a timer so that they can be switched in series after a certain time has elapsed. This means is disclosed. Therefore, when the means described in this publication is used, it is necessary to dispose two heat generating wires and two relays on each of the two heat generating surfaces, resulting in an increase in the number of parts and a cost increase. .

In Japanese Patent Laid-Open No. Sho 60-111829, an electric carpet is divided into two parts, heating wires are arranged on each heating surface, and a changeover switch is connected to both ends of each heating wire to heat either one of them. There are disclosed means for energizing only the wires, connecting two heating wires in parallel to increase the amount of heat, and connecting them in series to reduce the amount of heat. However, the means described in this publication has a problem that the power supply is short-circuited depending on the terminal selection of the two changeover switches.

On the other hand, in Japanese Utility Model Publication No. 62-144089, two heating wires form one heater wire,
Disclosed is a means for switching two heating wires in series or in parallel by a relay that simultaneously switches three relay contacts. However, the means disclosed in this publication does not disclose means for selectively selecting a heating surface divided into two parts or switching the amount of heat generation between large and small.

[0008]

By the way, as is well known, various electric appliances have come into widespread use, and the amount of electric power consumed per residence has increased. Among the electric appliances, household electric appliances with relatively large power consumption include electric carpets, electronic ovens, and large-sized TVs, and the opportunities to use these at the same time increase, and the breaker exceeds the contract current capacity of one house There is a problem that the chances of operating and power failure increase. Further, electronic devices such as personal computers and word processors, which are likely to break down or lose work until then, have come into widespread use in homes. In this case, it is preferable to stop the simultaneous use of the electric devices, but it may be difficult to stop the use of the electric carpet due to family structure or other reasons.

Therefore, in the prior art disclosed in Japanese Utility Model Laid-Open No. 4-8013, the carpet body is divided into two parts, and a heater having the same heat generation capacity is attached to each heat generating surface to generate heat on the entire surface. When connecting the heaters in parallel and connecting them to the power source and heating half of them, in the electric carpet where the power source is connected to only one heater on each side,
In order to use other electric appliances with a large current capacity at the same time, when the current used exceeds the contract current capacity, the heater is connected in series by manual switch operation to suppress the electric carpet current and keep it below the contract current capacity. To do.

However, the means described in this publication has a problem in that the power supply is short-circuited if the switch operation is mistaken, so that it is necessary to use a special switch capable of avoiding the short-circuit. The present invention has been made to solve the various problems described above, and has a simple circuit configuration in which heater loads are connected in series and in parallel without causing a short-circuit accident, and one of the heater loads is connected. It is an object of the present invention to provide a heater load connection switching device that can be used only.

[0011]

The structure of the heater load connection switching device of the present invention for achieving the above object is as follows.
A circuit in which the heater load, the first semiconductor power control element, and the second heater load are connected in series to an AC power source,
A second semiconductor power control element is connected in parallel to the series circuit of the first heater load and the first semiconductor power control element to form a series circuit of the second heater load and the first semiconductor power control element. , A third semiconductor power control element is connected in parallel, control means for turning on / off each of the first, second and third semiconductor power control elements is provided, and a first heater load and a second heater load are provided, The semiconductor power control element is controlled so that the series power connection, the parallel connection, or only one of them is energized independently.

The semiconductor power device may be implemented using a bidirectional semiconductor power control device such as a triac, or may be implemented using a unidirectional semiconductor power control device such as a thyristor. In addition, a conventional temperature sensor having a structure in which a pair of electrodes are arranged through a plastic temperature sensor made of an organic semiconductor that changes impedance according to temperature in the temperature sensor has a polarization effect when a direct current component flows through the temperature sensor. An error may occur due to a change in temperature-impedance characteristics. Further, when the unidirectional semiconductor power control element is used, unbalanced AC may be applied to the temperature sensor due to the voltage drop of the circuit, and a DC component may flow to the temperature sensor. Therefore, when using a unidirectional semiconductor power control device,
It is preferable that a circuit in which a temperature sensor and a capacitor are connected in series is connected to a commercial AC power source so that an error does not occur in the detected temperature.

[0013]

Since the three semiconductor power control elements are used and the connection of the two heater loads is switched so that only one of the heater loads is connected in series or in parallel, the phase level of the power source is changed. Switching control is possible with
Much more versatile switching control is possible than switching using a changeover switch or relay. For example, by alternately controlling the energization of two heater loads for each half-wave in one cycle, the power can be halved, and since there is no mechanical contact part, there is no risk of contact failure due to abrasion, etc. Switching
In-out, it is possible to eliminate the temperature difference between the two heaters, it is possible to reduce the number of parts. In addition, by igniting the semiconductor power control element at or near the zero cross of the power source to control the energization of the heater load, it can be turned on and off without generating a transient current in the circuit, and the occurrence of radio noise can be prevented. .

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the accompanying drawings. A basic circuit of a heater load connection switching device using the triac of the first embodiment will be described with reference to FIG. In the figure, an AC power source 1 is connected to a first heater load 2,
A circuit in which a first semiconductor power control element 3 and a second heater load 4 which are triacs are connected in series, and a first heater load 2 and a first semiconductor power control element 3 are connected in series. The second semiconductor power control elements 5 are connected in parallel to the semiconductor power control elements 3, 5 and 6 by the control device 7 including a one-chip microcomputer.
To control. Reference numeral R shown in FIG. 1 is a room temperature sensor.

FIG. 2 shows a temperature control circuit in which the basic circuit shown in FIG. 1 is applied to the electric carpet 8. Reference numeral 9 shown in FIG. 2 is a power plug for connecting to a commercial AC power supply (not shown). The first heater load 2 and the second heater load 4 are formed by coating a conventionally used resistance wire, and have the same heating capacity, for example, 300.
The electric carpet 8 of W was used, and the electric carpet 8 was divided into equal parts and arranged in each of the A ward and the B ward. The method of connecting the semiconductor power control elements 3, 5 and 6 to the heater loads 2 and 4 is substantially the same although the representation in the drawing is different from that in FIG.

Then, one temperature sensor 10 is connected to the first heater load 2 and the second heater load 4 across the sections A and B.
It was placed in parallel with. As shown in FIG. 3, the temperature sensor 10 includes a core thread 10a on which a linear primary conductor 10b is spirally wound, and a plastic temperature sensor 10c made of an organic semiconductor such as vinyl chloride is coated on the core primary conductor 10b and the outside thereof. Wrap a linear secondary conductor 10d from the
10e is coated, and the temperature is detected by changing the impedance of the plastic temperature sensing element 10c by changing the current flowing between the primary conductor 10b and the secondary conductor 10d. Incidentally, the voltage to be applied is an AC voltage, the plastic temperature sensitive body 10c is in cormorants'm not polarized.

One end of the primary conductor 10b of the temperature sensor 10 is connected to one pole of the power plug 9 through the resistor 11, and the other end is connected through the voltage dividing resistors 12a and 12b to the power plug. The secondary conductor 10d connected to the other pole (the side of the ground G) of 9 and having both ends short-circuited was connected to the side of the ground G to form the temperature detection circuit of the electric carpet 8. And the voltage dividing resistor 12
The voltage generated at the voltage dividing points of a and 12b was input to the control device 7 as a temperature signal via the rectifying / smoothing circuit formed by the diode 12c and the capacitor 12d. Since the plastic temperature sensing element 10c has a negative temperature gradient with respect to the temperature, the temperature signal becomes lower as the temperature of the electric carpet 8 becomes higher.

The selection of connection of the first heater load 2 and the second heater load 4 is made by the manual changeover switch 13. The manual change-over switch 13 is designed so that the heat generation surface can be selected from three types of A, B, and both A and B. In addition, the control device 7 of the first embodiment is provided with a program that controls the energization time according to the start of heating and the outside air temperature, and adjusts the heat generation amount.

The firing of the semiconductor power control elements 3, 5, 6 is
The first semiconductor power control element 3 is driven by the firing circuit P3, and the second semiconductor power control element 5 is driven by the firing circuit P1.
In addition, the third semiconductor power control element 6 is operated by the firing circuit P2. Each of the firing circuits P1, P2, P3 is a photocoupler composed of a light emitting diode L and a phototriac T. When the light emitting diode L conducts, the phototriac conducts by the light of the light emitting diode, and the semiconductor power control elements 3, 5 respectively. , 6 can be activated.

The controller 7 includes a power supply terminal 7a connected to the DC power supply circuit 14, a ground terminal 7b, an AC power supply phase signal input terminal 7c, a set temperature input terminal 7d, a temperature signal input terminal 7e, a connection switching terminal 7f, and Each firing circuit P1, P2, P3
The ignition terminals 7g, 7h, and 7i connected to are provided. The phase signal input terminal 7c is connected to the voltage dividing points of the voltage dividing resistors 15a and 15b, and the set temperature input terminal 7d is connected to the slide contact terminal of the variable resistor 16.

Next, the connection switching operation of the first embodiment will be described with reference to FIG. FIG. 4 shows the power supply waveform from the top, the method of connecting the first heater load 2 and the second heater load 4, the pulse output timing of the ignition circuits P1, P2, P3, the first heater load 2 and the 2 shows the relationship between the heater load 4 and the energization status of the heater load 4. As is apparent from FIG. 4, the ignition of the first embodiment is output in synchronization with the zero cross of the power supply voltage so that a transient current does not suddenly flow through the circuit components. Therefore, the ignition pulse is output every half wave. For example, the first heater load 2 and the second heater load 4 are controlled to half the electric power at the same time by energizing the section A with a positive half-wave and energizing the section B with a negative half-wave. be able to.

If only the first semiconductor power control element is ignited, the first heater load 2 and the second heater load 4 are connected in series and energized, so that when the load resistances are in parallel, It doubles and the power becomes 1/4. In this way, various controls can be easily performed. Therefore, increase the wattage of the temperature rise at the heating start time,
It is possible to perform control such as switching the wattage to three levels of high power, medium power, and low power of full power, 1/2 power, and 1/4 power depending on whether the set temperature is high or low.

FIG. 5 shows a heater load connection switching circuit according to the second embodiment, in which unidirectional semiconductor elements such as thyristors are used as the semiconductor power control elements 3, 5 and 6, and a light emitting diode emits light as an ignition element. using the phototransistor and a diode which conducts by those co down <br/> capacitor 17 to a temperature sensor 10 connected in series, the wattage of the first heater load 2 and the second heater load 4 of 400W Was formed in the same manner as in Example 1 except that Therefore, similar members are designated by the same reference numerals, and description thereof will be omitted.

The connection switching operation of the second embodiment will be described with reference to the operation diagram shown in FIG. In Example 2, since the unidirectional elements are used for the semiconductor power control elements 3, 5 and 6, the unbalanced AC may be applied to the temperature sensor due to the voltage drop of the circuit when only one cycle is energized. The capacitor 17 for removing the DC component was connected in series with the temperature sensor. Although the number of control modes of the second embodiment is smaller than that of the first embodiment, since connection switching control can be performed at the phase level of the power supply voltage cycle, it is much more detailed than when a mechanical switch such as a relay is used. Various switching controls can be performed.

[0025]

As described above, in the heater load connection switching device of the present invention, the connection switching of the two heater loads is performed by the three semiconductor power control elements, so that the following effects can be obtained. It becomes possible to perform connection switching control at the phase level of the power supply, which is much more detailed and does not have a temperature difference than using a mechanical switch, and various switching is possible. Therefore, if the heat generation capacity is increased to speed up the temperature rise in the early stages of heating, or if the heat generation capacity is adjusted by raising or lowering the outside air temperature or there is a risk of exceeding the contract current,
It is possible to make adjustments such as reducing the heat generation capacity without reducing the heat generation area of the electric carpet.

Since the connection of the heater load can be switched at or near the zero cross of the power source, there is no risk of generating a transient current in the circuit at the time of switching the connection, and switching can be performed without radio noise. Since a contactless switch is used, there is no risk of contact failure due to wear. The number of parts can be reduced.

[Brief description of drawings]

FIG. 1 is a basic circuit of a heater load connection switching device according to a first embodiment of the present invention.

FIG. 2 is a temperature control circuit diagram of an electric carpet using the basic circuit of FIG.

FIG. 3 is a partially cutaway perspective view for explaining the structure of the temperature sensor used in FIG.

FIG. 4 is an operation explanatory diagram of the first embodiment.

FIG. 5 is a temperature control circuit diagram of an electric carpet using the heater load connection switching device according to the second embodiment of the present invention.

FIG. 6 is an operation explanatory diagram of the second embodiment.

[Explanation of symbols]

1 AC power supply 2 1st heater load 3 1st semiconductor power control element 4 2nd heater load 5 2nd semiconductor power control element 6 3rd semiconductor power control element 7 Controller 8 Electric carpet 10 Temperature sensor P1 point Arc circuit P2 Firing circuit P3 Firing circuit T Trigger diode

Continuation of the front page (56) References JP-A 61-202214 (JP, A) JP-A 4-39882 (JP, A) Actually open 4-78413 (JP, U) Actually open 56-114089 (JP , U) (58) Fields investigated (Int.Cl. ⁷ , DB name) F24D 13/02 H05B 3/00 310

Claims (4)

(57) [Claims] 1. A circuit in which a first heater load, a first semiconductor power control element, and a second heater load are connected in series,
A second semiconductor power control element is connected in parallel to a series circuit of the first heater load and the first semiconductor power element connected to an AC power source, and the second heater load and the first semiconductor power control element are connected in parallel. A control means for connecting a third semiconductor power control element in parallel to the series circuit with the element and turning on / off each of the first, second and third semiconductor power control elements is provided, and the first heater load and the first heater load A heater load connection switching device that controls the semiconductor power control element so that the heater load of No. 2 is connected in series or in parallel, or only one of them is energized. 2. The heater load connection switching device according to claim 1, wherein the semiconductor power control element is a bidirectional semiconductor power control element. 3. The heater load connection switching device according to claim 1, wherein the semiconductor power control element is a unidirectional semiconductor power control element. 4. A circuit in which a temperature sensor having a pair of electrodes and a capacitor connected in series are connected to a commercial AC power source via a plastic temperature sensing element made of an organic semiconductor whose impedance changes with temperature, and the plastic sensing element is connected. 4. The heater load connection switching device according to claim 3, wherein a direct current does not flow through the heating element.