JP3337545B2 - Air conditioner - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a multi-type air conditioner comprising an outdoor unit and a plurality of indoor units.

[0002]

2. Description of the Related Art Generally, an air conditioner constitutes a heat pump type refrigeration cycle by sequentially connecting a compressor, a four-way valve, an outdoor heat exchanger, a flow control valve, and an indoor heat exchanger by piping. The cooling operation is performed by making the exchanger function as a condenser and the indoor heat exchanger as an evaporator. During heating, the indoor heat exchanger functions as a condenser, and the outdoor heat exchanger functions as an evaporator.

[0003] During operation, the capacity of the compressor is controlled according to the air conditioning load of the room where the indoor heat exchanger is installed.
The degree of superheat of the refrigerant in the evaporator is detected, and the flow rate of the refrigerant to the evaporator is controlled by adjusting the opening of the flow control valve so that the degree of superheat falls within a predetermined constant value.

[0004] The degree of superheat corresponds to the difference between the temperature of the refrigerant flowing out of the evaporator and the temperature of the refrigerant flowing into the evaporator, and is detected from the temperature detected by a temperature sensor attached to the pipe. Appropriate control of the degree of superheat is desired in order to ensure stable operation of the refrigeration cycle and to prevent liquid back to the compressor. For this reason, accuracy is required for the temperature detected by the temperature sensor.

[0005]

Generally, a thermal resistance element (for example, a negative temperature coefficient thermistor) is used as a temperature sensor, but this thermal resistance element has a risk of short-circuit failure or disconnection failure.

[0006] Among them, the disconnection is a change from a state without a failure to a state with a failure at once, so that a large difference occurs in the detected temperature before and after the failure. Therefore, regarding a disconnection, a failure can be immediately detected from a change in the detected temperature.

However, short-circuiting often progresses partially, and it is difficult to detect a failure because the detected temperature gradually changes. For this reason, the detection of the degree of superheat continues with a short circuit generated, which often adversely affects the operation and the life of the compressor.

[0008] The present invention has been made in view of the above circumstances,
It is an object of the present invention to provide an air conditioner that can accurately capture the temperature of a measurement target irrespective of a short-circuit failure of a temperature sensor, thereby enabling stable and proper operation.

[0009]

According to a first aspect of the present invention, there is provided an air conditioner, comprising: a plurality of temperature sensors provided at the same measurement point of a refrigeration cycle circuit; Or a means for selecting one of the higher ones according to the negative characteristic or the positive characteristic of each temperature sensor, and taking it as control information.

In the air conditioner of the second invention, a plurality of temperature sensors provided at the same measurement point of the refrigeration cycle circuit and having the same characteristics, means for detecting a failure of these temperature sensors, and the failure is not detected At this time, there is provided a means for selecting either the lower one or the higher one of the detected temperatures of the respective temperature sensors in accordance with the negative characteristic or the positive characteristic of each temperature sensor, and taking in the selected one as control information.

An air conditioner according to a third aspect of the present invention is provided with a plurality of temperature sensors having the same characteristics provided at a plurality of measurement points having a causal relationship with each other in a refrigeration cycle circuit, and among the detected temperatures of these temperature sensors, a lower temperature is used. One or the other, taking into account the above causal relationship, and the negative characteristics of each temperature sensor.
Means for selecting according to the gender or the positive characteristic and taking it as control information.

[0012]

In the air conditioner of the first invention, the temperatures at the same measurement point in the refrigeration cycle circuit are detected by a plurality of temperature sensors having the same characteristics, and the lower or higher of these detected temperatures is detected. A selection is made according to the negative characteristic or positive characteristic of each temperature sensor, and the selected temperature sensor is taken as control information.

In the air conditioner of the second invention, the temperature at the same measurement point in the refrigeration cycle circuit is detected by a plurality of temperature sensors having the same characteristics, and a failure of each temperature sensor is detected. Only when not performed, the lower or higher detected temperature among the detected temperatures of each temperature sensor is selected according to the negative characteristic or the positive characteristic of each temperature sensor, and the selected temperature is taken as control information.

In the air conditioner of the third invention, the temperatures of a plurality of measurement points having a causal relationship with each other in the refrigeration cycle circuit are detected by a plurality of temperature sensors having the same characteristics, and the lower of the detected temperatures of the temperature sensors. The higher or higher one is selected in consideration of the causal relationship and according to the negative characteristic or the positive characteristic of each temperature sensor, and the selected one is taken in as control information.

[0015]

An embodiment of the present invention will be described below with reference to the drawings.

As shown in FIG. 4, a plurality of indoor units B are connected to the outdoor unit A by piping. The outdoor unit A is
Compressors 1 and 2 housed in a common closed case are provided. The compressor 1 is an inverter-driven variable capacity compressor. The compressor 2 is a fixed power compressor driven by a commercial power supply.

A high pressure side pipe 4a is connected to a discharge port of the compressor 1. The high pressure side pipe 4b is connected to the discharge port of the compressor 2,
The check valve 3 is provided on the high pressure side pipe 4b. The high pressure side pipe 4 a and the high pressure side pipe 4 b are connected to the high pressure side pipe 4. The low pressure side pipe 5 is connected to the suction ports of the compressors 1 and 2.

An outdoor heat exchanger 8 is connected to the high-pressure side pipe 4 via an oil separator 6 and a four-way valve 7. A dryer 11 is connected to the outdoor heat exchanger 8 via a check valve 9 and a liquid tank 10. Heating expansion valve 1 for check valve 9
2 in parallel. An outdoor fan 13 is provided near the outdoor heat exchanger 8.

A strainer 15 is connected to the low-pressure side pipe 5 via an accumulator 14 and a four-way valve 7.

The oil separator 6 includes compressors 1 and 2
This is to extract the lubricating oil contained in the refrigerant discharged from the pump. An oil return pipe 16 is connected from the oil separator 6 to the low-pressure side pipe 5.

One end of a cooling bypass 17 is connected to a liquid side pipe between the check valve 9 and the liquid tank 10.
The other end of the cooling bypass 17 is connected to a low-pressure side pipe between the four-way valve 7 and the accumulator 14. The cooling bypass 17 is provided with a flow regulating valve 18.

With such piping connections, the outdoor unit A and each indoor unit B constitute a heat pump type refrigeration cycle circuit. At the time of cooling, the four-way valve 7 is set to the neutral state, whereby the refrigerant discharged from the compressors 1 and 2 is caused to flow in the direction of the solid arrow in the drawing to form a cooling cycle, and the outdoor heat exchanger 8 is connected to the condenser, Each indoor heat exchanger 33 functions as an evaporator. During heating, the four-way valve 7
This causes the refrigerant discharged from the compressors 1 and 2 to flow in the direction of the dashed arrow in the drawing to form a heating cycle, with each indoor heat exchanger 33 functioning as a condenser and the outdoor heat exchanger 8 functioning as an evaporator. Let it.

The flow control valve 18 and each flow control valve 3
Reference numeral 2 denotes a pulse motor valve whose opening continuously changes according to the number of input driving pulses. Hereinafter, the flow control valve is abbreviated as PMV.

The high pressure switch 21 and the temperature sensor 25 are mounted on the high pressure side pipe 4a. The high pressure switch 22 and the temperature sensor 26 are mounted on the high pressure side pipe 4b. The high-pressure switches 21 and 22 operate when the pressure of the refrigerant abnormally increases and reaches a predetermined value.

The pressure sensor 23 is mounted on the high pressure side pipe 4. A pressure sensor 24 and a temperature sensor 2
7 is installed. The temperature sensor 28 is attached to the outdoor heat exchanger 8. An outdoor air temperature sensor 29 is provided at a predetermined location of the outdoor unit A
Install.

Between the dryer 11 and the strainer 15,
Strainer 31 and flow regulating valve 32 of indoor unit B
Is connected to the indoor heat exchanger 33 via the. Indoor heat exchanger 3
3, an indoor fan 34 is provided. And PMV3
A pressure sensor 3 is provided on the liquid side pipe between the heat exchanger 2 and the indoor heat exchanger 33.
5 and the temperature sensor 37 are mounted. Indoor heat exchanger 33
The pressure sensor 36 and the temperature sensor 38 are attached to the gas side pipe connected to the. An indoor temperature sensor 39 is provided in the passage of the intake air of the indoor fan 34. The other indoor units B have the same configuration and the same connection.

The temperature sensors 37 and 38 are connected to the indoor heat exchanger 3
In the case of cooling functioning as an evaporator, the indoor heat exchanger 3
3 for detecting the degree of superheating of the refrigerant, and uses a temperature-sensitive resistance element such as a negative characteristic thermistor.

Although FIG. 1 shows only one temperature sensor 37, actually, as shown in FIGS.
Two temperature sensors 37a and 37b are prepared.

That is, a pair of thermo insertion pipes 41, 41 are attached to a pipe 40 connected to the indoor heat exchanger 33,
Two temperature sensors 3 are attached to the thermo insertion pipes 41, 41.
7a and 37b are inserted respectively. At the time of this insertion, the spring-like fixing members 42, 42 are inserted together, and the temperature sensors 37a,
37b is pressed against the inner peripheral surfaces of the thermo insertion pipes 41, 41 (on the pipe 40 side).

Although not shown, the temperature sensor 38 is actually provided with two temperature sensors 38a and 38b like the temperature sensors 37a and 37b.

FIG. 5 shows the control circuit.

The outdoor unit A has an outdoor control section 50. The indoor control unit 60 of each indoor unit B is connected to the outdoor control unit 50 by wiring.

The outdoor controller 50 comprises a microcomputer and its peripheral circuits. In this outdoor control unit 50,
Four-way valve 7, outdoor fan motor 13M, PMV18, high pressure switches 21, 22, pressure sensors 23, 24, temperature sensors 25, 26, 27, heat exchanger temperature sensor 28, outside air temperature sensor 29, commercial AC power supply 51, inverter And the switch 53 are connected.

The inverter 52 rectifies the voltage of the AC power supply line in the outdoor control unit 50, converts the rectified voltage into a voltage of a predetermined frequency by switching according to a command from the outdoor control unit 50, and outputs the voltage. This output is the driving power for the compressor motor 1M.

The switch 53 is, for example, a contact of an electromagnetic contactor. The compressor motor 2M is connected to an AC power supply line in the outdoor control unit 50 via a switch 53.

The indoor control unit 60 comprises a microcomputer and its peripheral circuits. In this indoor control unit 60,
PMV32, indoor fan motor 34M, pressure sensor 3
5, 36, temperature sensors 37a, 37b, 38a, 38
b, a room temperature sensor 39 and a remote control type operation device (hereinafter abbreviated as a remote control) 61 are connected.

The indoor controller 60 and the temperature sensor 37
The temperature detection circuit shown in FIG. 6 is interposed between the connection with the terminals a and 37b.

That is, a DC voltage V is applied to a series circuit of the temperature sensor 37a and the resistor Ra, and a voltage Va generated at the resistor Ra based on a change in the resistance value of the temperature sensor 37a (hereinafter referred to as an output voltage of the temperature sensor 37a). ) Is input to the outdoor controller 60 as detected temperature information. Temperature sensor 3
A DC voltage V is applied to a series circuit of the resistor 7b and the resistor Rb, and a voltage Vb (hereinafter, referred to as an output voltage of the temperature sensor 37b) generated in the resistor Rb based on a change in the resistance value of the temperature sensor 37b is detected temperature information. It is input to the outdoor control unit 60.

The indoor controller 60 and the temperature sensors 38a, 38
A similar temperature detection circuit is also interposed between the connection with b.

The indoor control section 60 mainly has the following functional means.

[1] Means for sending an operation mode command, an operation start command, and an operation stop command based on the operation of the remote controller 61 to the outdoor unit A.

[2] Means for finding the difference (air-conditioning load) between the temperature detected by the indoor temperature sensor 39 (suction air temperature) and the temperature set by the remote controller 61, and informing the outdoor unit A of the required capacity corresponding to the temperature difference. .

[3] Means for controlling the opening of the PMV 32 according to the required capacity of the indoor unit.

[4] During cooling, the lower one of the temperature sensors 38a and 38b on the outlet side of the indoor heat exchanger 33 is taken in as control information (detection temperature Te ₂ ), and the temperature sensor on the inlet side of the indoor heat exchanger 33 is taken. Means for taking in the lower one of 37a and 37b as control information (detection temperature Te ₁ ) and detecting the difference (= Te ₂ −Te ₁ ) between the two detected temperatures as the degree of superheating of the refrigerant in the indoor heat exchanger 33. .

[5] Temperature sensor 37a (and 38a)
When the output voltage Va is zero, the temperature sensor 37a (and 3
8a) is determined to be a disconnection failure, and when the output voltage Vb of the temperature sensor 37b (and 38b) is zero, the temperature sensor 37b
(And 38b) means for determining a disconnection failure.

[6] Temperature sensor 37a (and 38a)
Is determined, the temperature sensor 37b (and 38b) is used for detecting the degree of superheat, and the temperature sensor 37b
Means for using the temperature sensor 37a (and 38a) for detecting the degree of superheat when the disconnection failure of (and 38b) is determined.

[8] Means for correcting the opening of the PMV 32 so that the detected degree of superheat falls within a predetermined constant value.

The outdoor control section 50 mainly has the following functional means.

[1] The operating capacity of the compressors 1 and 2 (the number of operating compressors 1 and 2 and the operating frequency F of the compressor 1)
Means for controlling in accordance with the total required capacity of each indoor unit B.

[2] The four-way valve 7 is set to the neutral state, and the refrigerant discharged from the compressors 1 and 2 is supplied to the four-way valve 7, the outdoor heat exchanger 8, each of the flow regulating valves 32, each of the indoor heat exchangers 33, and the four-way valve. 7
Means for returning to the compressors 1 and 2 to perform a cooling operation.

[3] The four-way valve 7 is switched, and the refrigerant discharged from the compressors 1 and 2 is passed through the four-way valve 7, each indoor heat exchanger 33, each flow regulating valve 32, the outdoor heat exchanger 8, and the four-way valve 7. Compressor 1,
Means for returning to 2 and performing a heating operation.

Next, the operation of the above configuration will be described.

With the remote controller 61 of an arbitrary indoor unit B,
It is assumed that a desired operation mode and room temperature (hereinafter, referred to as a set temperature) are set, and an operation start operation is performed.

Then, at least the compressor 1 of the compressors 1 and 2 is started and the operation is started. In the cooling operation mode, the four-way valve 7 is set to the neutral state, and the refrigerant flows in the direction of the solid arrow in FIG. 1 to form a cooling cycle. Thereby, the outdoor heat exchanger 8 functions as a condenser, and the indoor heat exchanger 33 functions as an evaporator.

The indoor unit B calculates the difference between the temperature detected by the indoor temperature sensor 39 (suction air temperature) and the temperature set by the remote controller 61, and notifies the outdoor unit A of the required capacity corresponding to the temperature difference. Further, the opening of the PMV 32 is set to an opening according to the required capacity of the unit.

The outdoor unit A adjusts the operating capacity of the compressors 1 and 2 (the number of operating compressors 1 and 2 and the operating frequency F of the compressor 1) in accordance with the total required capacity of the indoor units B. Set to capacity.

For example, when the total required capacity is small, the output frequency F of the inverter 52 is controlled to
Performs a single variable capacity operation. When the total required capacity increases, the output frequency F of the inverter 52 is controlled and the switch 53 is turned on to execute the variable capacity operation of the compressor 1 and the fixed capacity operation of the compressor 2.

On the other hand, as shown in the flowchart of FIG. 7, it is confirmed whether the output voltage Va of the temperature sensor 37a is zero and whether the output voltage Vb of the temperature sensor 37b is zero. If both the output voltages Va and Vb are not zero, the refrigerant temperatures Ta and Tb based on the output voltages Va and Vb are detected based on the judgment that the temperature sensors 37a and 37b are not disconnected.

Since the temperature sensors 37a and 37b are negative thermistors, when the refrigerant temperatures Ta and Tb increase, the resistance values of the temperature sensors 37a and 37b decrease and the resistance R
The voltages Va and Vb generated at a and Rb increase. When the refrigerant temperatures Ta and Tb decrease, the resistance values of the temperature sensors 37a and 37b increase, and the voltage V generated at the resistances Ra and Rb increases.
a, Vb decrease.

When the refrigerant temperatures Ta and Tb are detected, the lower one of the detected temperatures is selected, and the lower one is selected.
As the temperature Te ₁ of the refrigerant flowing into the 3, and taking as control information.

Here, the lower detection temperature is taken in.
For the following reasons. That is, the temperature sensors 37a, 37b
If a partial short-circuit fault occurs in either of the above, an error occurs in the detected temperatures Ta and Tb. The direction of this error is a high direction because of the negative characteristic thermistor. Therefore, by taking in the lower detection temperature, the detection temperature of the temperature sensor in which the short-circuit failure has occurred is ignored, and temperature detection without error can be performed. what if,
Even when both of the temperature sensors 37a and 37b have a partial short-circuit fault, the lower detected temperature is the one with the smaller error.

If the temperature sensors 37a and 37b are PTC thermistors, the higher one of the detected temperatures Ta and Tb may be selected.

The detection temperature T of the temperature sensors 38a and 38b
The same selection is made for a and Tb, and the selected detected temperature is taken in as the temperature Te ₂ of the refrigerant flowing out of the indoor heat exchanger 33 and as control information.

When the intake of the temperatures Te ₁ and Te ₂ is completed, the difference between the two temperatures (= Te ₂ −Te ₁ ) is detected as the degree of superheating of the refrigerant in the indoor heat exchanger 33. Then, the opening of the PMV 32 is corrected so that the detected degree of superheat falls within a predetermined constant value.

Therefore, irrespective of the short-circuit failure of the temperature sensor, the temperature of the refrigerant can be accurately detected, the superheat degree can be controlled with high accuracy, and stable and proper operation can be performed.

When a disconnection fault occurs in the temperature sensor 37a, the output voltage Va of the temperature sensor 37a becomes zero. At this time, the temperature sensor 37a determines that a disconnection failure has occurred,
The superheat degree is detected using the detected temperature Tb of the temperature sensor 37b. In the event of a disconnection failure of the temperature sensor 37b, the detected temperature Ta of the temperature sensor 37a is used.

In the event of a disconnection failure, it is not possible to select the one with a lower detected temperature, so there is a concern that the accuracy of the detection of the degree of superheat is reduced. However, the merit that the operation can be continued is greater than that.

In the above embodiment, only the disconnection failure was determined, but as shown in FIG. 8, the temperature sensors 37, 37b
(And 38a, 38b) detected temperature Ta, Tb difference Δ
When the temperature difference ΔT exceeds the predetermined value ΔTs, the temperature sensor with the higher detected temperature is determined to be a short-circuit failure based on the determination that the short-circuit failure has progressed to an unacceptable state. However, it may be configured to notify the user by displaying the information.

In the above embodiment, two temperature sensors are mounted at the same measurement point. However, two temperature sensors are provided at a plurality of measurement points having a causal relationship with each other. Either the lower or the higher one may be selected in consideration of the causal relationship and according to each temperature characteristic, and the selected one may be taken as control information. This is effective when it is difficult to attach two temperature sensors to the same measurement point due to restrictions on the mounting locations of the temperature sensors.

[0070]

As described above, the air conditioner of the first invention detects the temperature at the same measurement point in the refrigeration cycle circuit by a plurality of temperature sensors having the same characteristics, and the lower of these detected temperatures. The higher or higher detection temperature is selected according to the negative or positive characteristics of each temperature sensor, and this is taken in as control information, so that the temperature of the measurement target can be accurately determined regardless of the short-circuit failure of the temperature sensor. And stable and proper operation is possible.

The air conditioner of the second invention detects the temperature at the same measurement point in the refrigeration cycle circuit with a plurality of temperature sensors having the same characteristics, and detects abnormality of each temperature sensor.
Only when this abnormality is not detected, a lower or higher detection temperature among the detection temperatures of each temperature sensor is selected according to the negative or positive characteristic of each temperature sensor, and the selected temperature is taken as control information. Therefore, the temperature of the object to be measured can be accurately detected irrespective of the short-circuit failure of the temperature sensor, thereby enabling stable and proper operation.

In the air conditioner of the third invention, the temperatures of a plurality of measurement points having a causal relationship with each other in the refrigeration cycle circuit are detected by a plurality of temperature sensors having the same characteristic, and the lower of the detected temperatures of the temperature sensors. square or higher a and the upper in consideration of the above causality selected according to the negative characteristics or positive JP <br/> of each temperature sensor, since the collected Komu configure it as control information, short of the temperature sensor Regardless of the failure, and without any restrictions on the mounting location of the temperature sensor, etc.
The temperature of the object to be measured can be accurately detected, thereby enabling stable and proper operation.

[Brief description of the drawings]

FIG. 1 is an exploded perspective view for explaining attachment of a temperature sensor according to an embodiment of the present invention.

FIG. 2 is a diagram showing an attached state of the temperature sensor in the embodiment.

FIG. 3 is a side view of FIG. 2;

FIG. 4 is a configuration diagram of a refrigeration cycle of the same embodiment.

FIG. 5 is a block diagram of a control circuit according to the embodiment.

FIG. 6 is a wiring diagram of a temperature detection circuit in the embodiment.

FIG. 7 is a flowchart for explaining the operation of the embodiment.

FIG. 8 is a flowchart for explaining the operation of a modification of the embodiment.

[Explanation of symbols]

A: outdoor unit, B: indoor unit, 1: variable capacity compressor, 2: fixed capacity compressor, 8: outdoor heat exchanger, 32 ...
PMV (flow control valve), 33 ... indoor heat exchanger, 37a,
37b, 38a, 38b: temperature sensor, 50: outdoor control unit, 60: indoor control unit.

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) F25B 49/02 570 F24F 11/02 103 G01K 7/00 381 G01K 7/22 G01K 7/24

Claims (3)

(57) [Claims] 1. A multi-type air conditioner comprising an outdoor unit and a plurality of indoor units, comprising: a plurality of temperature sensors having the same characteristics provided at the same measurement point of a refrigeration cycle circuit; Means for selecting either the lower one or the higher one according to the negative characteristic or the positive characteristic of each temperature sensor, and taking in the control information as control information. 2. A multi-type air conditioner comprising an outdoor unit and a plurality of indoor units, wherein a plurality of temperature sensors having the same characteristics provided at the same measurement point of the refrigeration cycle circuit and failures of these temperature sensors are detected. Means for performing, when this failure is not detected, one of the lower or higher of the detected temperatures of the respective temperature sensors is selected according to the negative characteristic or the positive characteristic of each temperature sensor, and that is selected as control information. An air conditioner comprising: an intake means; 3. A multi-type air conditioner comprising an outdoor unit and a plurality of indoor units, wherein a plurality of temperature sensors having the same characteristics are provided at a plurality of measurement points having a causal relationship with each other in a refrigeration cycle circuit. of the temperature sensor sensing the temperature, and the in on lower or higher either one of the consideration of the causality
Means for selecting according to the negative characteristic or the positive characteristic of the temperature sensor, and taking in the control information as control information.