JP2000046403A - Multiple type air conditioner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an air conditioner capable of preventing a compressor from being interrupted with the low cost without increasing a torque of the compressor. SOLUTION: A refrigerant circuit is constructed by connecting annularly a compressor 1, an outdoor heat exchanger 3, an electrical motor driven expansion valve 4, and an indoor heat exchanger 5. An inverter control section 11 controls inverter output voltage from an inverter 20 to drive a motor of the compressor 1 with the inverter 20. The inverter control section 11 when the compressor 1 is with a high load, and operation frequency is reduced from a state where the operation frequency is high, a reduction rate of the operation frequency of the compressor 1 is more reduced than a predetermined value. Further, the compressor 1 is prevented from being interrupted owing to insufficient torque of the motor of the compressor 1 when the operation frequency is reduced from the state with the high operation frequency.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a compressor, a condenser,
A refrigerant circuit in which the expansion means and the evaporator are connected in a ring,
The present invention relates to an air conditioner in which a motor of the compressor is driven by an inverter.

[0002]

2. Description of the Related Art Conventionally, as an air conditioner, a refrigerant circuit in which a compressor, a condenser, expansion means and an evaporator are connected in a ring, an inverter for driving a motor of the compressor, and an output of the inverter are provided. And an inverter control unit for controlling the operation frequency of the compressor, wherein the operation frequency is reduced at a constant rate when the operation frequency is reduced.

[0003]

By the way, in the above-mentioned air conditioner, when the operating frequency is reduced from a state where the compressor is operated at a high operating frequency, the motor torque follows the decrease in the operating frequency with good followability. Although the load decreases, the load (refrigerant pressure) followability is poor, and the load decrease is slower than the motor torque decreases due to the decrease in the operating frequency. For this reason,
If the rate of decrease when the operating frequency is reduced from a high load is too fast, the compressor may stop due to insufficient torque. In the air conditioner, the motor torque of the compressor is increased in order to prevent the compressor from stopping, so that there is a problem that the cost is high.

An object of the present invention is to provide an air conditioner that can prevent the compressor from stopping at low cost without increasing the motor torque of the compressor.

[0005]

To achieve the above object, an air conditioner according to a first aspect of the present invention includes a refrigerant circuit in which a compressor, a condenser, an expansion means, and an evaporator are connected in a ring, In an air conditioner including an inverter that drives a motor and an inverter control unit that controls the output of the inverter, the inverter control unit reduces the operating frequency from a state where the compressor is under a high load and a high operating frequency. In this case, the rate of decrease in the operating frequency of the compressor is made smaller than a predetermined value.

According to the air conditioner of the first aspect, the inverter control unit reduces the operating frequency of the compressor when the compressor is operating under a high load and a high operating frequency. By setting the rate lower than a predetermined value, making the decrease rate slower than usual, and matching the rate of decrease in motor torque with the rate of decrease in load so that the motor of the compressor does not run out of torque, Avoid stopping.

[0007] The air conditioner according to the second aspect of the present invention is the first aspect of the invention.
In the air conditioner, a condensation temperature detection sensor that detects the condensation temperature of the refrigerant in the condenser, and a condensation temperature determination unit that determines whether the condensation temperature detected by the condensation temperature detection sensor is equal to or higher than a predetermined temperature. Wherein the compressor has a high load when the condensing temperature determining unit determines that the condensing temperature is equal to or higher than a predetermined temperature.

According to the air conditioner of the second aspect, when the condensing temperature judging section judges that the condensing temperature is equal to or higher than the predetermined temperature, it is determined that the compressor has a high load. The load condition of the vehicle can be accurately grasped.

[0009] The air conditioner according to the third aspect is characterized by the first aspect.
In the air conditioner, the condensation temperature detection sensor for detecting the condensation temperature of the refrigerant in the condenser, the evaporation temperature detection sensor for detecting the evaporation temperature of the refrigerant in the evaporator, and the condensation temperature detection sensor A temperature difference determination unit that determines whether a temperature difference between the condensation temperature and the evaporation temperature detected by the evaporation temperature detection sensor is equal to or greater than a predetermined temperature difference,
When the temperature difference judging section judges that the temperature difference between the condensing temperature and the evaporation temperature is equal to or larger than a predetermined temperature difference, the compressor has a high load.

According to the air conditioner of the third aspect, when the temperature difference judging section judges that the temperature difference between the condensing temperature and the evaporating temperature is equal to or greater than a predetermined temperature difference, the compressor operates under a high load. Thus, the load state of the compressor can be accurately grasped.

[0011] The air conditioner of claim 4 is characterized in that
In any one of the air conditioners of (1) to (3), when the operating frequency is reduced for protection control, the inverter control unit sets the predetermined value without lowering the decreasing rate of the operating frequency of the compressor. Features.

According to the air conditioner of the fourth aspect, in the protection control for protecting the compressor and the inverter from being damaged due to an abnormal operation or the like, the reduction rate of the operating frequency of the compressor is set to the predetermined value. Since the operating frequency is immediately reduced to stop the compressor, the compressor can be reliably protected without continuing the operation in an abnormal state.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an air conditioner according to the present invention will be described in detail with reference to the illustrated embodiments.

FIG. 1 is a schematic configuration diagram of an air conditioner according to an embodiment of the present invention, in which 1 is a compressor having a built-in motor (not shown), and 2 is one end on the discharge side of the compressor 1. Is an outdoor heat exchanger having one end connected to the four-way valve 2, and 4 is an electric expansion valve as expansion means having one end connected to the other end of the outdoor heat exchanger 3. Reference numeral 5 denotes an indoor heat exchanger having one end connected to the other end of the electric expansion valve 4. The compressor 1, the four-way valve 2, the outdoor heat exchanger 3, the electric expansion valve 4, and the indoor heat exchanger 5 constitute a refrigerant circuit. Also,
The air conditioner includes a first temperature sensor 21 that detects the temperature of the refrigerant in the outdoor heat exchanger 3, a second temperature sensor 22 that detects the temperature of the refrigerant in the indoor heat exchanger 5, and a discharge of the compressor 1. High pressure side pressure sensor 23 for detecting the pressure on the suction side, and low pressure side pressure sensor 24 for detecting the pressure on the suction side of the compressor 1
And

The air conditioner receives signals from the first temperature sensor 21, the second temperature sensor 22, the high-pressure side pressure sensor 23, and the low-pressure side pressure sensor 24, and receives signals from the compressor 1, the electric expansion valve 4, and the like. And the like, and an inverter unit 20 that receives a control signal from the control device 10 and drives the motor of the compressor 1. Note that the compressor 1 outputs a signal representing rotation speed information to the control device 10. The inverter unit 20 includes a power supply (not shown)
And a current transformer CT as an input current detection sensor is provided on a power supply line connecting the inverter unit 20 and a power supply.

The control device 10 includes a microcomputer, an input / output circuit, and the like.
1, an input current determining unit 12 for determining an input current detected by the current transformer CT, a high-pressure side pressure determining unit 13 for determining a high-side pressure detected by the high-side pressure sensor 23, A pressure difference discriminating unit 14 for discriminating a pressure difference between the high pressure side pressure detected by the high pressure side pressure sensor 23 and the low pressure side pressure detected by the low pressure side pressure sensor 24, and the first temperature sensor 21 (or A condensing temperature judging unit 15 for judging the condensing temperature detected by the second temperature sensor 22), and a condensing temperature detected by the first temperature sensor 21 (or the second temperature sensor 22) and the second temperature sensor 2
2 (or a first temperature sensor 21) and a temperature difference discriminator 16 for discriminating a temperature difference from the evaporation temperature detected by the second temperature sensor 21.

In the air conditioner, when the four-way valve 2 is switched to the switching position indicated by the dotted line during the cooling operation and the compressor 1 is operated, the refrigerant discharged from the compressor 1 causes the outdoor heat exchanger as a condenser to operate. The refrigerant condensed at 3 and condensed is supplied to the electric expansion valve 4
After the expansion, the water is evaporated in the indoor heat exchanger 5 as an evaporator, and returns to the compressor 1. In this case, the first temperature sensor 21 functions as a condensation temperature detection sensor, and the second temperature sensor 22 functions as an evaporation temperature detection sensor.

In the above air conditioner, when the operating frequency of the compressor 1 is reduced by the operating frequency lowering command, the lowering rate is set to a predetermined value when the compressor 1 has a low load, while the compressor 1 When the load is high, the reduction rate is made smaller than a predetermined value.

FIG. 2 is a flowchart showing the operation frequency reduction command processing of the control device 10. The operation frequency reduction command processing of the control device 10 will be described below according to the flowchart of FIG.

First, when the operating frequency lowering command process is started, it is determined in step S1 whether or not the lowering is due to the protection control. The protection control prevents the compressor 1 and the inverter 20 from being damaged during abnormal operation.

Next, in step S2, it is determined whether or not the compressor 1 has a high load. If it is determined that the load is high, the process proceeds to step S3, in which the rate of reduction is slowed, and this processing is terminated.

On the other hand, if it is determined in step S1 that the load is reduced due to the protection control, or if it is determined in step S2 that the load is not high, the process proceeds to step S4, where the reduction rate is set to normal, and the process is terminated.

In the above-described operation frequency lowering command processing, when the compressor 1 has a high load, the condensation temperature of the outdoor heat exchanger 3 as the condenser is detected by the first temperature sensor 21 as the condensation temperature detection sensor. And the condensation temperature determining unit 15
Is when it is determined that the condensation temperature is equal to or higher than the predetermined temperature.

Further, a second condensing temperature detecting sensor is provided.
1 The outdoor heat exchanger 3 as a condenser by the temperature sensor 21
Of the indoor heat exchanger 5 as an evaporator by the second temperature sensor 22 as an evaporating temperature detecting sensor, and the temperature difference discriminating unit 16 determines the difference between the condensing temperature and the evaporating temperature. When it is determined that the temperature difference is equal to or greater than the predetermined temperature difference, the compressor 1 may be under a high load.

Further, when one of the following conditions (1) to (3) is satisfied, the compressor 1 may have a high load. (1) The input current of the inverter unit 20 is detected by the current transformer CT, and the input current determination unit 12
When it is determined that the input current is equal to or higher than the predetermined current. (2) When the high-pressure side pressure sensor 23 detects the high-pressure side pressure, and the high-pressure side pressure determination unit 13 determines that the high-pressure side pressure is equal to or higher than a predetermined pressure. (3) The high-pressure side pressure sensor 23 detects the high-pressure side pressure, the low-pressure side pressure sensor 24 detects the low-pressure side pressure, and the pressure difference discriminating unit 14 determines that the pressure difference between the high-pressure side pressure and the low-pressure side pressure is a predetermined pressure. When it is determined that the difference is greater than or equal to the difference.

As described above, the inverter control unit 11
When the operating frequency of the compressor 1 is reduced from a state where the load is high and the operating frequency is high, the decreasing rate of the operating frequency of the compressor 1 is made smaller than a predetermined value, and the decreasing rate is made slower than usual. The rate of decrease in motor torque and the rate of decrease in load are matched so that the motor of the compressor 1 does not run out of torque. By doing so, the compressor 1
Can be prevented from stopping due to insufficient torque.

Further, a second condensing temperature detecting sensor is provided.
1 The outdoor heat exchanger 3 as a condenser by the temperature sensor 21
Of the compressor 1 by detecting the condensation temperature of the compressor 1 by determining that the condensation temperature is equal to or higher than a predetermined temperature.
Can be accurately grasped.

Further, a second condensing temperature detecting sensor is provided.
1 The outdoor heat exchanger 3 as a condenser by the temperature sensor 21
And the second temperature sensor 22 as an evaporating temperature detecting sensor detects the evaporating temperature of the indoor heat exchanger 5 as an evaporator, and the temperature difference discriminator 16 determines the temperature between the condensing temperature and the evaporating temperature. By determining that the difference is equal to or greater than the predetermined temperature difference, the load state of the compressor 1 can be accurately grasped.

When the compressor 1 is protected, the rate of decrease in the operating frequency of the compressor 1 is set as the predetermined value,
Since the compressor 1 is stopped by immediately lowering the operating frequency, the compressor 1 can be reliably protected without continuing the operation in an abnormal state.

In the above embodiment, the cooling operation has been described. However, the same operation and effect can be obtained during the heating operation. In this case, the four-way valve 2 is switched to the switching position indicated by the solid line, the outdoor heat exchanger 3 functions as an evaporator, the indoor heat exchanger 5 functions as a condenser, and the first temperature sensor 21 functions as an evaporation temperature detection sensor. The second temperature sensor 22 serves as a condensation temperature detection sensor.

The predetermined value of the decrease rate of the operating frequency of the compressor 1 and the value when the operating frequency is made smaller than the predetermined value may be appropriately set in accordance with the configuration and the operating capacity of the air conditioner.

[0032]

As is apparent from the above description, the air conditioner according to the first aspect of the present invention comprises a refrigerant circuit in which a compressor, a condenser, expansion means and an evaporator are connected in a ring, and a motor of the compressor. In an air conditioner including an inverter to be driven and an inverter control unit that controls an output of the inverter,
The inverter control unit is configured to reduce the operating frequency from a state where the compressor has a high load and a high operating frequency,
The reduction rate of the operating frequency of the compressor is made smaller than a predetermined value.

Therefore, according to the air conditioner of the first aspect of the present invention, when the operating frequency of the compressor is reduced from a state where the load is high and the operating frequency is high, the inverter control unit reduces the operating frequency of the compressor. Stopping the compressor can be prevented by making the reduction rate smaller than a predetermined value, making the reduction rate slower than usual, and preventing the motor of the compressor from running out of torque.

According to a second aspect of the present invention, in the air conditioner of the first aspect, when the condensation temperature of the refrigerant in the condenser detected by the condensation temperature detection sensor is equal to or higher than a predetermined temperature, the condensation temperature is determined. Since it is determined that the compressor has a high load when the section determines, the load state of the compressor can be accurately grasped.

According to a third aspect of the present invention, in the air conditioner of the first aspect, the condensation temperature of the refrigerant in the condenser detected by the condensation temperature detection sensor and the evaporation temperature detected by the evaporation temperature detection sensor. When the temperature difference determining unit determines that the temperature difference between the refrigerant and the evaporation temperature of the refrigerant of the compressor is equal to or greater than the predetermined temperature difference, the compressor is considered to be heavily loaded, so that the load state of the compressor must be accurately grasped. Can be.

In the air conditioner according to the present invention, when the operating frequency is reduced for protection control in the air conditioner according to any one of the first to third aspects, the inverter control unit includes: Since the predetermined value is set without lowering the decrease rate of the operating frequency of the compressor, the operating frequency is quickly reduced and the compressor is stopped. Can be protected.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of an air conditioner according to an embodiment of the present invention.

FIG. 2 is a flowchart showing an operation frequency reduction command process of the control device of the air conditioner.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Compressor, 2 ... Four-way valve, 3 ... Outdoor heat exchanger, 4 ... Electric expansion valve, 5 ... Indoor heat exchanger, 10 ... Control device, 11 ... Inverter control unit, 12 ... Input current discrimination unit, 13 ... High-pressure side pressure judging unit, 14... Pressure difference judging unit, 15... Condensation temperature judging unit, 16.
First temperature sensor, 22: second temperature sensor, 23: high pressure side pressure sensor, 24: low pressure side pressure sensor, CT: current transformer.

Claims (4)

[Claims] 1. A refrigerant circuit in which a compressor (1), a condenser (3), an expansion means (4) and an evaporator (5) are connected in a ring, and an inverter for driving a motor of the compressor (1). (20) and an inverter control unit for controlling the output of the inverter (20)
In the air conditioner including (11), the inverter control section (11) operates the compressor when the compressor (1) is reduced in operating frequency from a high load and high operating frequency state. An air conditioner characterized in that the frequency reduction rate is smaller than a predetermined value. 2. The air conditioner according to claim 1, wherein the condensation temperature detection sensor detects a condensation temperature of the refrigerant in the condenser, and the condensation temperature detection sensor detects the condensation temperature. A condensing temperature determining unit that determines whether the condensing temperature is equal to or higher than a predetermined temperature.
(15) wherein the compressor (1) has a high load when the condensing temperature judging section (15) judges that the condensing temperature is equal to or higher than a predetermined temperature. Machine. 3. The air conditioner according to claim 1, wherein a condensation temperature detection sensor (21) for detecting a condensation temperature of the refrigerant in the condenser (3), and an evaporation temperature of the refrigerant in the evaporator (5). And a temperature difference between the condensation temperature detected by the condensation temperature detection sensor (21) and the evaporation temperature detected by the evaporation temperature detection sensor (22). A temperature difference determining unit (16) for determining whether or not the temperature difference is greater than or equal to a predetermined temperature difference when the temperature difference determining unit (16) determines that the temperature difference between the condensation temperature and the evaporation temperature is equal to or greater than a predetermined temperature difference. An air conditioner wherein the compressor (1) has a high load. 4. The air conditioner according to claim 1, wherein when the operating frequency is reduced for protection control, the inverter control unit (11) controls the compressor (1). An air conditioner characterized in that the predetermined value is set without lowering the operating frequency reduction rate.