JP2869301B2 - Air conditioner control circuit - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a control circuit for an air conditioner for supplying control power from a switching transformer to an electronically controlled expansion valve (a control valve driven by a stepping motor).

[0002]

2. Description of the Related Art In a conventional control circuit for an air conditioner of this type, in order to efficiently and precisely control the operation of the air conditioner, a compressor is controlled by an inverter and an expansion valve is controlled electronically. Is performed. In order to implement this, an inverter control power supply and an electronic control power supply are required. In an air conditioner, the control power supply is constituted by a switching transformer.

FIG. 4 shows a switching transformer 10 and its peripheral circuits. Each power supply output 31 controls an inverter of a compressor, a power supply output for electronically controlling an expansion valve, a power supply output to a dummy load, and a microcontroller. A power output 32 such as a control circuit by a computer is obtained from the switching transformer 10. The switching transformer 10 has a characteristic that intermittent oscillation easily occurs when the load decreases, and in the worst case, the power supply output may be stopped. The expansion valve receiving the power supply from the switching transformer 10 has the greatest effect on the intermittent oscillation due to the decrease in the load. The intermittent oscillation does not occur during the operation of the expansion valve. .

Therefore, in the conventional air conditioner, when the expansion valve is stopped, a load replacing the expansion valve, that is, a pseudo load is connected to the switching transformer 10 to prevent intermittent oscillation.

FIG. 5 shows a control circuit for the expansion valve 42 and the dummy load 41. The expansion valve 42 and the dummy load 41
The power supply from the control power Vc supplied from the switching transformer 10 is connected to each other via a driver IC 43 that controls on / off of the control power Vc.
On / off control is performed by the expansion valve control signal 45 and the dummy load control signal 44 input to the control signal 3. Expansion valve control signal 4
When the voltage of 5 becomes 0V and the expansion valve 42 is stopped, the pseudo load control signal 44 is controlled to the ON operation voltage of 5V to turn on the power supply to the pseudo load 41.

[0006]

In the control circuit of the conventional air conditioner as described above, a dedicated dummy load 41 and a dummy load driver IC are required, and the dummy load 4 is not required.
The temperature on the substrate on which 1 is placed rises, and it is necessary to suppress the rise in temperature and reduce the influence on peripheral circuits,
There has been a problem that the arrangement space needs to be enlarged and processing such as ventilation is required.

[0007]

SUMMARY OF THE INVENTION A control circuit for an air conditioner according to the present invention solves the above-mentioned problems and supplies control power from a switching transformer to a compressor controlled by an inverter and an expansion valve controlled by an electronic control. When the expansion valve is controlled to be turned off, the expansion valve itself connected to the switching transformer is used as a pseudo load.

[0008]

According to the present invention, there is no need to provide a dedicated dummy load as in the prior art, and the problem relating to heat generation can be surely eliminated because the expansion valve itself is used as a load.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a control circuit for an air conditioner according to the present invention will be described below with reference to FIGS. The following examples are specific examples of the present invention and do not limit the technical scope of the present invention.

FIG. 1 is a configuration diagram of a control circuit of an expansion valve in an embodiment of a control circuit of an air conditioner of the present invention, and FIG. 2 is a flowchart showing a control procedure of the control circuit of FIG. FIG. 3 is a timing chart showing the sequence of energizing the internal coil of the expansion valve.

The control circuit 1 is connected to an expansion valve (a control valve driven by a stepping motor, ie, an electronic control valve) from a Vc terminal connected to a control power supply comprising the switching transformer 10 and its peripheral circuits shown in FIG. Valve) 4 and internal coils (motor coils of a stepping motor for driving a control valve) A, B, C, and D. Power supplied to the driver (driver IC) 5 is turned on / off (ON / O).
FF). The driver 5 has a control element for controlling energization to each of the coils A, B, C, and D, and each control element is turned on / off by a control signal input thereto.

That is, the control signal 2 controls the internal coil A of the expansion valve 4, the control signal 3 controls the internal coil B of the expansion valve 4, the control signal 6 controls the internal coil C of the expansion valve 4, and the control signal 7 controls the expansion valve. 4 are controlled respectively.

The control signals 2, 3, 6, and 7 are output from an air conditioner control device (not shown), and control signals are output in accordance with overall control of the air conditioner.

The control circuit 1 configured as described above is controlled by the input control signals A, B, C, and D according to the procedure of the flowchart shown in FIG.

That is, in step 1 of FIG. 2, in the case of the mode in which the expansion valve 4 operates, the switching transformer 1
Since the intermittent oscillation of 0 does not occur, the normal expansion valve control routine is started in step 2, and the internal coils A, B, C, and D of the expansion valve 4 are turned on and off at the timing shown in FIG. Then, the control proceeds from step 1 to step 8 shown in FIG.
Repeat step 1 in order. This operation is a control operation in the forward rotation direction, and when the rotation is reversed (reverse rotation), the internal coils A, B, C, and D of the expansion valve 4 are supplied in the reverse order from step 8 to step 1 → step 8. Is controlled.

If it is not necessary to operate the expansion valve 4, basically, the power supply to the internal coils A, B, C, and D should be turned off. Since the load becomes a load and intermittent oscillation easily occurs, the process proceeds to step 3 and enters a pseudo output routine.

In the pseudo output routine, of the steps 1 to 8 in FIG. 3, two internal coils immediately adjacent to the step when the operation of the expansion valve 4 is stopped are simultaneously energized (step 2). , 4, 6 or 8), and by applying current to the two internal coils, the load state of the switching transformer 10 can be set almost in the same manner as during the operation of the expansion valve, thereby preventing intermittent oscillation. be able to.

In the above case, during the operation, the two internal coils and one internal coil are energized alternately, so that during the stop of the expansion valve, the two coils are turned on and off so that their powers are equal. If it is controlled, it can be controlled to exactly the same power.

In another embodiment, the energization at the time of OFF is repeated in a short time by forward rotation and reverse rotation, and the power consumption can be kept exactly the same as the position of the expansion valve. In this case, for example, if step 4 is the off position,
Step 4 → Step 5 → Step 3 are repeatedly performed.

[0020]

Since the control circuit of the air conditioner of the present invention has the above-described configuration, it is possible to exactly control the power consumption when the expansion valve is operating and when it is stopped. Intermittent oscillation due to a decrease in load can be reliably prevented, and a pseudo load resistor as in the related art is not required, and the influence of heat generated by the resistance on the surroundings can be completely eliminated.

[Brief description of the drawings]

FIG. 1 is a main part configuration diagram showing one embodiment of a control circuit of an air conditioner of the present invention.

FIG. 2 is a flowchart illustrating a control procedure of a control circuit of the air conditioner of the present invention.

FIG. 3 is a timing chart showing the order of energizing the expansion valve of the control circuit of the air conditioner of the present invention.

FIG. 4 is a configuration diagram of a conventional switching transformer of an air conditioner and its peripheral circuits.

FIG. 5 is a main part configuration diagram of a control circuit of a conventional air conditioner.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Control circuit 2 Control signal 3 Control signal 4 Expansion valve 5 Driver IC 6 Control signal 7 Control signal 10 Switching transformer

Claims (3)

(57) [Claims] In an air conditioner control circuit for supplying control power from a switching transformer to an electronically controlled expansion valve, when the expansion valve is controlled to be turned off, energization is performed so that a motor of the expansion valve does not rotate. A control circuit for an air conditioner, further comprising control means for controlling energization of each motor coil so as to reduce a difference in power consumption between when the expansion valve is turned on and when the expansion valve is turned off. 2. The control circuit for an air conditioner according to claim 1, wherein the energization when the control unit is turned off is energization control in which the motor of the expansion valve does not rotate. 3. An expansion valve according to claim 2, wherein the control means controls the energization at the time of OFF to repeat forward rotation and reverse rotation of the expansion valve in a short time so that the power consumption is the same and the position of the expansion valve is controlled to the same position. 2. A control circuit of the air conditioner according to 1.