JPH09145185A - Air conditioner and control method thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To surely and rapidly perform switching of cooling and heating operations using a four-way valve. SOLUTION: An air conditioner comprises a capacity variable type compressor 1b and a constant speed type compressor 1a provided in parallel in a refrigerant circuit, and is capable of switching of cooling and heating operations by switching of a four-way valve 4. The air conditioner further comprises means 50 for performing of switching of the four-way valve 4 after the constant speed type compressor 1a is started up to generate high pressure in the refrigerant circuit.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an air conditioner and a control method thereof, and in particular, a variable capacity compressor having a power control mechanism and a constant speed compressor are arranged in parallel in a refrigerant circuit. The present invention relates to an air conditioner capable of switching between heating and cooling operations by a four-way valve equipped with a differential pressure piston and a control method thereof.

[0002]

2. Description of the Related Art Generally, there is known an air conditioner in which a variable capacity compressor and a constant speed compressor are provided in parallel in a refrigerant circuit, and a cooling / heating operation can be switched by switching a four-way valve. In this type, the four-way valve is generally equipped with a differential pressure piston, and the discharge side refrigerant of the compressor is introduced into the small diameter piston side pressure chamber formed by this differential pressure piston, and the large diameter piston side pressure The refrigerant on the discharge side or the refrigerant on the suction side of the compressor is selectively introduced into the chamber to switch the four-way valve.

In a variable capacity compressor using an inverter, the inverter compressor is activated to generate a pressure difference between high pressure and low pressure of the refrigerant in the refrigerant circuit, and then the four-way valve is switched. Therefore, the switching is conventionally performed smoothly.

[0004]

However, in the case of using, for example, a variable capacity compressor having a power control mechanism, which enables mechanical capacity switching control without using an inverter compressor, this variable capacity is used. When the type compressor is activated at startup, it takes time for the discharge pressure to rise to a predetermined pressure, so high pressure does not occur in the refrigerant circuit, and it is impossible to switch the four-way valve for cooling and heating operation. There's a problem.

Therefore, an object of the present invention is to solve the above-mentioned problems of the prior art, and to perform switching of heating / cooling operation using a four-way valve reliably and quickly, and an air conditioner therefor. It is to provide a control method.

[0006]

According to a first aspect of the present invention, a variable capacity compressor and a constant speed compressor are provided in parallel in a refrigerant circuit, and a heating / cooling operation can be switched by switching a four-way valve. In the air conditioner described above, the constant-speed compressor is activated to provide a means for switching the four-way valve after generating a pressure difference between a high pressure and a low pressure of the refrigerant in the refrigerant circuit. Is.

According to a second aspect of the present invention, there is provided an air conditioner in which a variable capacity compressor and a constant speed compressor are provided in parallel in a refrigerant circuit, and a cooling / heating operation can be switched by switching a four-way valve, The four-way valve is provided with a differential pressure piston, the discharge side refrigerant of the compressor is introduced into a small diameter piston side pressure chamber formed by the differential pressure piston, and the discharge side refrigerant or suction of the compressor is introduced into a large diameter piston side pressure chamber. A side refrigerant is selectively guided, and a means for switching the four-way valve is provided, and the constant speed compressor is operated for a fixed period of time at the start of the operation, and the pressure difference between the high pressure and the low pressure of the refrigerant in the refrigerant circuit is reduced. After generating
It is characterized in that a means for switching the four-way valve is provided.

According to a third aspect of the invention, an air conditioner control in which a variable capacity compressor and a constant speed compressor are provided in parallel in a refrigerant circuit and cooling / heating operation can be switched by switching a four-way valve In the method, in the initial stage of starting, until the discharge pressure reaches a predetermined pressure or more, the constant speed compressor is operated to generate a pressure difference between the high pressure and the low pressure of the refrigerant in the refrigerant circuit, and then the four-way valve. It is characterized by switching.

According to these inventions, a large differential pressure is constantly generated in the piston of the four-way valve in the initial stage of starting the compressor, so that the switching of the four-way valve can be performed reliably and quickly, thereby performing the heating / cooling operation. Switching can be performed reliably and quickly.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION A first embodiment of the present invention will be described below with reference to the drawings. In FIG. 1, reference numeral 100 denotes an outdoor unit of the air conditioner, and this outdoor unit 100
A plurality of indoor units 200 are connected to each other. The compressor 1 of the outdoor unit 100 includes a constant speed compressor 1a and a compressor equipped with a power control mechanism (hereinafter, simply referred to as "P /
C compressor ". ) 1b, the compressors 1a, 1b are arranged in parallel in the refrigerant circuit.

The constant speed compressor 1a has an output of 6 horsepower, for example, and the P / C compressor 1b has a maximum output of 4 horsepower, and can be reduced to an output of 2 horsepower. The discharge pipe 2 a of the compressor 1 is connected to the four-way valve 4 via the oil separator 3 and is connected to the outdoor heat exchanger 5 via the four-way valve 4. This outdoor heat exchanger 5 includes an indoor unit 200
Through the indoor expansion valve 6 of the indoor heat exchanger 7,
Further, it is connected to the accumulator 8 via the four-way valve 4, and is connected to the suction pipe 2b of the compressor 1 via the accumulator 8.

The mechanism of the P / C compressor 1b described above will be briefly described. As shown in FIGS. 2 and 3, the rotary compressor element is housed in the closed container 10 of the P / C compressor 1b. The compressor element includes an intermediate partition plate 11 and a pair of cylinders 1 provided on both sides of the intermediate partition plate 11.
2 and 13 are provided. The first holes 14 and 15 provided on the inner side walls of both cylinders 12 and 13, and the first holes 14 and 15,
Second holes 16 and 17 provided in both cylinders 12 and 13 so as to communicate with 15, and a third hole 18 provided in the intermediate partition plate 4 that communicates with the second holes 16 and 17 are formed. There is.

Second holes 16 and 17 of both cylinders 12 and 13
The pistons 19 and 20 are housed therein, and a coil spring (a leaf spring or a bellows may be used as long as it is an elastic body) 21 is disposed across the pistons 19 and 20. The fourth hole 23, which communicates with the second holes 16 and 17 of both cylinders 12 and 13 by the recess 22 formed in the cylinders 12 and 13,
24, and a control port 25 for selectively communicating the fourth holes 23, 24 with the low pressure side or the high pressure side of the external refrigerant circuit.

In the P / C compressor 1b having the above-described structure, the low pressure side of the refrigerant circuit is communicated with the control port 25, and the fourth hole 23, 24 and the second hole 16 via the recess 22 are provided.
By applying a low-pressure side pressure to 17, the pistons 19 and 20 are moved in the separating direction and the first holes 14 and 15 are opened, as shown in FIG.
The gas in the compression process inside the first hole 14, the second hole 16,
Flow through the third hole 18, the second hole 17, and the first hole 15 into the other cylinder 13 in the suction process, whereby the P / C compressor 2 is operated at half power (2 horsepower). . On the other hand, during normal operation, as shown in FIG. 3, the high pressure side of the refrigerant circuit and the control port 25 are communicated with each other, and the fourth hole 2
By applying a high-pressure side pressure to the second holes 16 and 17 via the recesses 3 and 24 and the recess 22, the pistons 19 and 20 are moved in the approaching direction, and both the first holes 14 and 15 are closed. , The movement of the refrigerant between the cylinders 12 and 13 is blocked, whereby the P / C compressor 1b is operated at full power (4 horsepower).

In this air conditioner, the first internal control circuit 2c with the high pressure release valve 9a interposed is connected to the oil separator 3 and the control port 25 of the P / C compressor 1b, and the low pressure control valve 9b is interposed. The second internal control circuit 2d is connected to the suction pipe 2e of the P / C compressor 1b. Further, the oil separator 3 and the suction pipe 2g of the compressor 1b are connected by the external control circuit 2f with the return valve 9c interposed.

According to this embodiment, referring to FIG. 1, first, the high pressure release valve 9a is opened and the low pressure release valve 9b is closed. In this state, the control port 25 of the P / C compressor 1b
The oil separated by the oil separator 3 is guided to the first internal control circuit 2c. Therefore, the control port 25 is loaded with high pressure, and the P / C compressor 1b operates at full power.

Next, the high pressure open valve 9a is closed and the low pressure open valve 9b is opened. In this state (state of FIG. 2), the low-pressure fluid in the suction pipe 2e acts on the control port 25 of the P / C compressor 1b, so that the P / C compressor 2 operates at half power. Further, when the external control circuit 2f return valve 24 is opened, a part of the refrigerant discharged from the compressor 1 is returned to the accumulator 19, so that the output of 1 horsepower is reduced. This external control circuit 2f is used for capability control.

On the other hand, the four-way valve has a spool 31 housed in a cylinder housing 30 as shown in FIGS. This spool 31 is provided with a small diameter piston 32 and a large diameter piston 33 at one end, and these pistons 32, 3
The two pressure chambers 3 in the cylinder housing 30
It is formed in 4,35. Further, communication holes 36, 37, 38, 39 are formed in the cylinder housing 30, and two of the four ports are selectively communicated by the spool 31. The four-way valve 4 has a pilot valve 40. It has three ports 41, 42, 43. And port 42
Is in communication with the pressure chamber 34 of the cylinder housing 30, the port 41 is in communication with the port 38 of the cylinder housing 30, and the port 43 is in the pressure chamber 3 of the cylinder housing 30.
It is in communication with 5.

Therefore, the four-way valve 4 is operated by the pressure acting on the small diameter piston 32 and the large diameter piston 33. When the pilot valve 40 is operated as shown in FIG. 4 to connect the ports 42 and 43 to each other, the pressure chamber 34 and the pressure chamber 35 are connected to each other, so that the spool 31 has a force for moving the spool 31 to the left. Occurs, which causes the spool 31 to move to the left. Then, the ports 36 and 39 are communicated with each other, and the ports 37 and 38 are communicated with each other.

When the pilot valve 40 operates as shown in FIG. 5 to connect the port 41 and the port 43 to each other, the pressure chamber 35 is connected to the port 38, and in this case, the pressure acting on the small diameter piston 32 ( P1) is larger than the pressure (P2) acting on the large-diameter piston and moves to the right rather than the force (P2 x S2 (where S2 is the pressure acting area of the small-diameter piston 32)) that moves the spool 31 to the left. Force (P
When 1 × S1 (where S1 is the pressure acting area of the large-diameter piston 33) is larger, the spool 31 is moved to the right as shown in FIG.

The constant speed compressor 1a, the P / C compressor 1b, and the high pressure release valve 9 of the first internal control circuit 2c described above.
a, low pressure release valve 9 of the second internal control circuit 2d
b, the return valve 9c of the external control circuit 2f, the four-way valve 4
The pilot valve 40 and the like are controlled by the control device 50 as described later. A sensor 60 that detects the discharge pressure of the compressor 1 is provided on the discharge side of the compressor 1, and the detection signal of this sensor 60 is input to the control device 50.

Next, the operation of this embodiment will be described. In the cooling operation, the refrigerant discharged from each of the compressors 1a and 1b is sent to the outdoor heat exchanger 5 via the oil separator 3 and the four-way valve 4, and then circulates through the indoor unit 200 and is sent to the accumulator 8. To be The heating operation is performed by switching the four-way valve 4 and changing the flow of the refrigerant.

When the air conditioning load (horsepower) in the room fluctuates, (1) each compressor 1a, 1b is turned on and off, (2)
ON / OF of the return valve 9c of the external control circuit 9c
F, (3) By turning on and off the high pressure release valve 9a of the first internal control circuit 2c and the low pressure release valve 9b of the second internal control circuit 2d, as shown in FIG. Control for each.

For example, when the required horsepower is 10 horsepower,
Turn on the two compressors 1a and 1b. In this case, the high pressure release valve 9a of the internal control circuit 2c is turned on, and high pressure oil is added to the control port 25 of the P / C compressor 1b. The P / C compressor 1b is in the state shown in FIG. If the required horsepower is 9 horsepower, two compressors 1a,
When 1b is turned on and the return valve 9c is turned on, the discharge amount for one horsepower is returned to the accumulator 8 by the external control circuit 2f, and the operation at 9 horsepower is performed. When the required horsepower is 8 horsepower, the two compressors 1a and 1b are turned on and the return valve 9c is turned off.
In the state of F, the high pressure release valve 9a is turned off and the low pressure release valve 9b is turned on.

In this case, as shown in FIG. 2, due to the action of the power control mechanism, the horsepower of the P / C compressor 1b becomes 2 horsepower (half power), and the horsepower of the other constant speed compressor 1a becomes Since it is 6 horsepower, it gives a total of 8 horsepower.
When the required horsepower is 7 horsepower, two compressors 1a, 1b
Is turned on, the return valve 9c is turned on, the high pressure release valve 9a is turned off, and the low pressure release valve 9b is turned on.

In this case, due to the action of the power control mechanism, the P / C compressor 1b becomes 2 horsepower and the discharge amount of 1 horsepower is returned to the accumulator 8 by the external control circuit 2f, resulting in a total of 7 horsepower. . Similarly, as shown in FIG. 6, by combining the constant speed compressor 1a, the P / C compressor 1b, the high pressure release valve 9a, the low pressure release valve 9b, and the return valve 9c with ON and OFF, from 1 horsepower. Fine control of 1 horsepower is possible up to 10 horsepower.

According to this embodiment, the four-way valve 4 cannot be switched unless there is a pressure difference between the high pressure and the low pressure of the refrigerant in the refrigerant circuit. In the P / C compressor 1b, the initial stage of startup is a transitional period of pressure increase, and referring to FIG. 2, if the holes 14 and 15 are not blocked, the compressor 1b is in an unload state. Therefore, the pressure difference between the high pressure and the low pressure of the refrigerant in the refrigerant circuit does not occur. This makes it impossible to switch the four-way valve 4. Therefore, according to this embodiment, in the initial stage of startup,
Always operate the P / C compressor 1b without operating it.
After the pressure difference between the high pressure and the low pressure of the refrigerant in the refrigerant circuit is generated by operating a for a predetermined time, the four-way valve 4 is switched.

When the discharge pressure from the compressor 1 becomes a pressure sufficient to operate the spool 31 of the four-way valve 4, the detection signal of the sensor 60 is input to the control device 50 to load the air conditioning load. The air conditioning operation according to is performed.

[0029]

As described above, according to the air conditioner and the method of controlling the same according to the present invention, the constant speed compressor is operated at the initial stage of start-up, so that the high pressure and the low pressure of the refrigerant in the refrigerant circuit are controlled. Since the four-way valve is switched after the pressure difference is generated, a large pressure acts on the four-way valve, so that the cooling / heating operation can be switched almost certainly.

[Brief description of the drawings]

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

FIG. 2 is a cross-sectional view showing a low pressure application state of a power control mechanism incorporated in a P / C compressor.

FIG. 3 is a cross-sectional view showing a high pressure applied state of a power control mechanism incorporated in a P / C compressor.

FIG. 4 is a sectional view conceptually showing a four-way valve, showing a state in which a spool is operated to one side.

FIG. 5 is a conceptual cross-sectional view showing a state where the spool of the four-way valve is actuated to the other side.

FIG. 6 is a diagram showing variable capacity control of the air conditioner according to the present invention.

[Explanation of symbols]

 1 Compressor 1a Constant-speed compressor 1b P / C compressor 4 Four-way valve 31 Differential pressure piston 36, 37, 38, 39 port 40 Pilot valve 41, 42, 43 port 50 Controller 60 Pressure sensor

Claims (3)

[Claims] 1. An air conditioner in which a variable capacity compressor and a constant speed compressor are provided in parallel in a refrigerant circuit, and cooling / heating operation can be switched by switching a four-way valve. An air conditioner comprising means for switching the four-way valve after the activation to generate a pressure difference between high pressure and low pressure of the refrigerant in the refrigerant circuit. 2. An air conditioner in which a variable capacity compressor and a constant speed compressor are provided in parallel in a refrigerant circuit and cooling / heating operation can be switched by switching a four-way valve, wherein the four-way valve is a differential pressure piston. The discharge side refrigerant of the compressor is guided to the small diameter piston side pressure chamber formed by the differential pressure piston, and the discharge side refrigerant or the suction side refrigerant of the compressor is selectively guided to the large diameter piston side pressure chamber. The four-way valve is provided with a means for switching the four-way valve, and the constant-speed compressor is operated for a certain period of time at the initial stage of operation to generate a pressure difference between high pressure and low pressure of the refrigerant in the refrigerant circuit. An air conditioner comprising means for switching valves. 3. A control method for an air conditioner, comprising a variable capacity compressor and a constant speed compressor in parallel in a refrigerant circuit, wherein heating / cooling operation can be switched by switching a four-way valve. The four-way valve is switched after the constant speed compressor is operated to generate a pressure difference between high pressure and low pressure of the refrigerant in the refrigerant circuit until the discharge pressure reaches a predetermined pressure or more. Air conditioner control method.