JPS5938438B2 - compressor protector - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention, in a compressor driven by a pole number switching motor, avoids reverse braking torque that occurs when switching from a few pole operation to a multi pole operation, and also prevents frequent pole number switching. Provide a protective device to prevent

Conventionally, in a compressor driven by a pole switching motor that can switch the number of poles between two-pole operation and four-pole operation, when the number of poles is continuously switched from two poles to four poles, the pole number switching electric motor
Even if the wire is connected to the pole winding, the 4
It rotates at a higher speed than the synchronous speed (1800 rpm) of polar operation, and at that time, an excessive reverse braking torque is generated, which creates a large stress on the rotating shaft connected to the electric motor, which may cause damage.

In addition, when applying the above compressor to an air conditioner and adjusting the air conditioning capacity, for example, when starting operation, two-pole operation is performed to rapidly cool the room, and even when switching to four-pole operation, the room remains cool. The temperature of the walls, etc. was still high, and the indoor temperature rose within a short period of time, making it necessary to operate with two poles again, resulting in frequent switching of the number of poles, which could shorten the life of the compressor. .

The present invention aims to improve these drawbacks, and will be described below with reference to the drawings showing one embodiment thereof.

1 is a compressor which compresses refrigerant, and during cooling operation, the compressed high-pressure refrigerant is sent from a discharge pipe 2 to a heat source side heat exchanger 4 via a four-way switching valve 3, where it is condensed and liquefied; Check valve 6
The indoor air is guided to the first expansion device 7 via the 1st throttle device 7, where it is depressurized and expanded, cooled by the user-side heat exchanger 8, passed through the four-way switching valve 3 again, and compressed from the suction pipe 10 of the compressor 1 via the accumulator 9. Inhaled into machine 1.

When the compressor 1 is operating at low capacity, the three-way valve 5 is closed, and the second throttle device 11 and the first throttle device 7 are connected in series to increase refrigerant throttling resistance.

Next, during heating operation, the four-way switching valve 3 is switched, and the high-pressure refrigerant discharged from the compressor 1 enters the user-side heat exchanger 8 via the four-way switching valve 3, heating the indoor air, and the refrigerant itself is liquefied and condensed. It is led to the second throttle device 11 via the first throttle device 7, is depressurized and expanded, is endothermically evaporated in the heat source side heat exchanger 4, passes through the four-way switching valve 3 again, passes through the accumulator 9, and is then transferred to the compressor from the suction pipe 10. 1 is inhaled.

During heating operation, the check valve 6 allows refrigerant to flow through the refrigerant circuit regardless of whether the three-way valve 5 is open or closed.

Reference numeral 12 denotes an air blower, which is driven by a motor 13 and has fans 14 and 15 that ventilate the user side heat exchanger 8 and the heat source side heat exchanger 4, respectively.

The pole number switching motor 16 that drives the compressor 1 is a three-phase induction motor, in which the windings of each phase are connected in series.
It becomes a polar motor, and the windings of each phase are connected in parallel to form a two-pole motor.

The motor 16 has multi-pole terminals 16a, 16b, and 16c connected to the power source P by the contacts 18 of the 4-pole switch 17, resulting in 4-pole operation, and the small-pole terminal 16d is connected to the contact 20 of the 2-pole switch 19. , 16e, and 16f are connected to the power source P to perform two-pole operation.

21 is a control power supply applied between terminals 22 and 23, and terminal 22 is connected to a power switch 24.

The power switch 24 is further connected to a heating/cooling changeover switch 25 and a winding 47 of the motor 13.

The cooling/heating changeover switch 25 has a contact 26 that is closed during cooling operation, and contacts 27 and 28 that are closed during heating operation.
The contacts 26 and 27 are connected to contacts 30 and 31 of a thermostat 29, which detects the room temperature and switches to open and close the thermostat 29, respectively.

Further, the thermostat 29 is connected to the 4-pole switch 1 via a contact 33 of the pole number switching switch 32 that is closed when the 4-pole switch 32 is closed.
7, and is connected to a coil 38 that drives the drive coil 36 of the bipolar switch 19 and the auxiliary relay 37 via a contact 35 that is closed when bipolar.

Further, the contact 35 is connected in parallel with the self-holding contact 39 of the auxiliary relay 37.

Also, via the normally closed contact 40 of the auxiliary relay 37,
Further, the drive coil 34 and the drive coil 36 are each connected to the terminal 23 via a normally open contact 41.

Further, a coil 45 that drives a contact 44 of a power switch 43 having a phase advancing capacitor 42 is connected to the load side of the thermostat 29 .

A contact point 28 of the cooling/heating changeover switch 25 is connected to an electromagnetic coil 46 that changes over the four-way changeover valve 3 shown in FIG.

Next, the operation will be explained.

During cooling operation, the cooling/heating changeover switch 25 is set to the cooling side and the contact 26 is closed.

When the power switch 24 is closed, the winding 46 is energized, the motor 13 is rotated, and the heat source side heat exchanger 4 and the usage side heat exchanger 8 are ventilated.

If the room temperature is higher than the set temperature, the contact 30 of the thermostat 29 is closed, the coil 45 is energized, the power switch 43 is activated, and if the pole number switching switch 32 is set to the 4-pole operation side, the contact 30 is closed. The coil 34 is energized through the coil 34, and the motor 16 is operated as a four-pole motor.

Next, switch the pole number switching switch 32 to the two-pole operation side and contact 35
When closed, the coil 38 of the auxiliary relay 37 is energized, the contact 41 is closed, and the coil 36 of the two-pole switch 19 is energized, and the motor 16 is switched to a two-pole winding, resulting in two-pole operation. The compressor 1 rotates at high speed and is operated at high capacity, and the self-holding contact 39 of the auxiliary relay 37 is closed.

Next, when switching from 2-pole operation to 4-pole operation, even if the contact 35 of the pole number switching switch 32 is opened and the contact 33 is closed, the auxiliary relay 37 is self-held and the normally closed contact 40 is not opened. The coil 34 is not energized and the normally open contact 41 is
remains closed, and the coil 36 continues to be energized via the self-holding contact 39, continuing bipolar operation.

Then, when the room temperature falls and the thermostat 29 is switched and the contact 30 is opened, the current supply to the coils 36 and 45 is stopped and the compressor 1 is stopped.

At this time, the self-holding function of the auxiliary relay 37 is also released, and the normally closed contact 40 is closed.Then, when the room temperature rises and the contact 30 of the thermostat 29 is closed again, the contact 30 of the pole number switching switch 32 is closed. The coil 34 is energized through the coil 34, and the motor 6 becomes a four-pole winding, and the coil 45 is energized, and the power switch 43 is activated, resulting in four-pole operation.

In other words, as mentioned above, switching from 2-pole operation to 4-pole operation is performed after the compressor is stopped by the thermostat 30, so it is impossible to prevent reverse braking torque that occurs when switching from 2-pole operation to 4-pole operation. In addition, after the room is cooled sufficiently in two-pole operation and the thermostat is turned off, the system switches to four-pole operation, so four-pole operation, that is, low-capacity operation, can be continued for a long time with a low indoor cooling load. ,
Efficient air conditioning operation is possible, and conventional air conditioners use two-pole operation to quickly cool the indoor air at the start of operation, and reduce the wall temperature of the room like when switching to four-pole operation. (As a result, even if the compressor is operating at low capacity with 4 poles, the indoor temperature will rise rapidly and the compressor will have to switch back to 2-pole operation after a short period of time, resulting in frequent switching of the number of poles and shortening the life of the compressor. You can prevent things like that from happening.

This also applies when the pole number switching switch 32 detects the indoor air temperature and automatically switches the number of poles similarly to the thermostat 29, and also when the pole number switching switch 32 is manually switched. The same can be said.

In particular, when switching manually, when starting the air conditioner,
Even if you use pole operation to cool the room at high capacity, and then switch the number of poles manually, the room may not be sufficiently cooled and the switch will be made after the thermostat 29 is turned off, so the room may not be cooled enough and 4-pole operation is required. There is no need to switch to two-pole operation again after a difficult period of time after startup due to insufficient cooling capacity of the engine and the room temperature rising.

Next, during the heating operation, the cooling/heating changeover switch 25 is switched and the contacts 27 and 28 are closed to switch to the heating operation.

That is, the electromagnetic coil 46 is energized by the contact 28, the four-way switching valve 3 is switched, the flow of the refrigerant is reversed, and the refrigerant circuit becomes a heating circuit.

In addition, the contact 31 of the thermostat 29 is connected to the contact 27.
Coils 34, 36, 38 and 45 are energized through.

In this case, the difference from the above-mentioned cooling operation is that the contact 31 of the thermostat 29 is closed when the indoor temperature drops below the set temperature, and is opened when the indoor air temperature is above the set temperature. In addition, when switching from 2-pole operation to 4-pole operation, thermostat 29 turns OFF.
The switching after F is the same, and the effect is also the same.

In the above embodiment, a pole number switching motor that switches between two poles and four poles has been described, but it is clear that a motor that switches to other pole numbers may also be used.

As is clear from the above embodiments, the compressor protection device of the present invention includes an electric motor that drives the compressor, a multi-pole switch that energizes the motor as a multi-pole motor, and a small-pole switch that energizes the motor as a small-pole motor. It has a pole switch, a pole number switching switch, a thermostat, and an auxiliary relay, and has a multi-pole contact of the pole number switching switch, a coil that operates the multi-pole switch, and a normally closed state of the auxiliary relay. A pole number switching circuit in which a series circuit with a contact is connected in parallel to a series circuit of a small pole contact of the pole number switching switch, a coil that operates the small pole switch, and a normally open contact of the auxiliary relay. A self-holding circuit is formed in which a coil for operating the auxiliary relay is connected in series to the self-holding contact of the auxiliary relay connected in parallel to the small-pole contact of the pole number switching switch. The thermostat is connected in series to the parallel circuit of the holding circuit and the pole number switching circuit, and is connected to the power supply, so that even if the pole number switching switch is switched from low pole operation to multi pole operation during low pole operation. , the self-holding circuit does not switch immediately, and when the thermostat stops energizing the compressor and the thermostat starts energizing the compressor again, it is operated in multi-pole operation, and it is operated in multi-pole operation. In addition to preventing reverse braking torque that occurs when switching to pole operation, it maintains sufficiently high capacity operation until the thermostat activates during low pole operation, and continues operation for a sufficiently long time even when switching to multi pole operation and low capacity operation. This makes it possible to operate with high efficiency, and the number of poles does not change frequently, resulting in the effect of lengthening the life of the compressor.

[Brief explanation of drawings]

FIG. 1 is a schematic configuration diagram of an air conditioner equipped with a compressor having a protection device of the present invention, and FIG. 2 is an electrical circuit diagram of a compressor protection device showing an embodiment of the present invention. 1...-Compressor, 16...-Pole number switching motor (electric motor), 17-...4-pole switch (multi-pole switch), 19...- -2-pole switch (small-pole switch), 21...-control power supply, 29...-thermostat, 32...pole number switching switch, 33...
・-・Contact (contact for multiple poles), 34.36...-Drive coil, 35...Contact (contact for few poles), 37-
... Auxiliary relay, 38 ... Coil, 39.
-...-Self-holding circuit, 40...--Normally closed contact,
41...--Normally open contact.

Claims (1)

[Claims] 1. An electric motor that drives the compressor, a multi-pole switch that energizes this motor as a multi-pole motor, a small-pole switch that energizes the motor as a small-pole motor, a pole number switching switch, a thermostat, and an auxiliary relay. and a series circuit of the multi-pole contact of the pole number switching switch and the coil that operates the multi-pole switch with the normally closed contact of the auxiliary relay is connected to the small number of pole contact of the pole number switching switch. A pole number switching circuit is formed which is connected in parallel to a series circuit of a coil for operating the small pole switch and a normally open contact of the auxiliary relay; A self-holding circuit is formed by connecting a coil that operates the auxiliary relay in series to the self-holding contacts of the auxiliary relay connected in parallel, and the thermostat is connected in series to the parallel circuit of this self-holding circuit and the pole number switching circuit. A compressor protection device that is connected to a power source.