JPH05113252A - Refrigerating cycle - Google Patents

Abstract

PURPOSE:To make it possible to lower delivery temperatures even when a condenser load has become excessively large in a refrigerating cycle with a thermostatic expansion valve. CONSTITUTION:A compressor 31, condenser 32, thermostatic expansion valve 33, and evaporator 34 are connected successively. A refrigerant suction line 35a from the evaporator 34 to the compressor 31 is divided into a main line 36 and a by-pass line 37. A heater 39 for heating refrigerant is provided in the line 37 and a thermostatic expansion valve 40 is located downstream of the heater 39. A control device 42 is provided to put an input for heating into the heater 39 when the delivery temperature of the compressor 31 exceeds a predetermined value.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a refrigeration cycle apparatus for controlling a refrigerant using a temperature type expansion valve or an electric expansion valve, and more particularly to a refrigeration cycle apparatus capable of controlling a refrigerant under a liquid back condition. ..

[0002]

2. Description of the Related Art FIG. 5 shows a conventional refrigerating cycle device for controlling a refrigerant by using a temperature type expansion valve.

The compressor 1, the condenser 2, the thermal expansion valve 3 and the evaporator 4 are sequentially connected by a refrigerant pipe 5, thereby forming a closed refrigeration cycle.

The refrigerant suction line 5a from the evaporator 2 to the compressor 1 is provided with a temperature type expansion valve temperature sensitive tube 6 which is connected to the temperature type expansion valve 3 via a capillary tube 6a. At the same time, the line 5a and the thermal expansion valve 3 are connected by a pressure equalizing pipe 7.

When the superheat of the refrigerant suction line 5a becomes small during the cycle operation, the thermal expansion valve 3 performs a throttling operation due to the contraction of the gas in the temperature sensitive cylinder 6 and the capillary tube 6a, and thereby to the evaporator 4. While the control for increasing the superheat is performed by decreasing the supply amount of the liquid refrigerant of the above, when the superheat becomes large, the thermal expansion valve 3 operates in the opening direction due to the gas expansion in the temperature sensing cylinder 6 and the capillary tube 6a. Then, the supply amount of the liquid refrigerant to the evaporator 4 is increased and superheat reduction control is performed, whereby automatic adjustment is performed so that the superheat of the refrigeration cycle becomes constant.

Further, FIG. 6 shows a system configuration of a split type heat pump type air conditioner as a conventional example of a refrigeration cycle apparatus which controls a refrigerant using an electric expansion valve.

The compressor 11, the indoor heat exchanger 12, the electric expansion valve 13 and the outdoor heat exchanger 14 are sequentially connected by a refrigerant pipe 15, and the suction line 15a and the discharge line 15b of the compressor 11 are four-way valves. 16 are arranged, and thereby a heat pump type refrigeration cycle is configured. The suction line 15 a of the compressor 11 is provided with a refrigerant suction temperature detector 17.

Further, in the arrangement for connecting the expansion valve upstream and downstream portions of the refrigerant pipe 15 and the suction line 15a of the compressor 11,
Saturation temperature detection circuit 19 having a capillary tube 18
The saturation temperature detecting circuit 19 is provided with a saturation temperature detector 20.

Then, the superheat in the suction line 15a is detected by the suction temperature detector 17, the saturation temperature is detected by the saturation temperature detector 20, and these are input to the control device 21 to obtain the superheat amount. At the same time, the correction amount of the valve opening is obtained according to the difference (deviation) between the obtained superheat amount and the set value,
As a result, the motor 13a of the electric expansion valve 13 is controlled.

[0010]

The conventional refrigeration cycle apparatuses described above have the following problems.

That is, in the refrigeration cycle apparatus using the temperature type expansion valve 3 shown in FIG. 5, the superheat is appropriately adjusted under standard conditions to perform efficient operation. If the superheat is constant under a condition where the condensation temperature is high, such as when the refrigerant is excessively high, the refrigerant discharged from the compressor may have an excessively high temperature.

Further, in the refrigeration cycle apparatus using the electric expansion valve 13 shown in FIG. 6, for example, when the superheat is reduced due to some disturbance and the liquid is in the liquid back state, the value of the superheat is It becomes 0, and the difference from the set value is always constant during this period. Therefore, the electric expansion valve 13
The opening degree correction amount is also constant, and the valve opening degree may not be controlled depending on the degree of liquid back.

The present invention has been made in view of the above circumstances. A first object of the present invention is to provide a refrigeration cycle apparatus using a temperature type expansion valve even if the condenser load becomes excessively large. The second purpose is to control the valve opening even when the superheat becomes small due to disturbance or the like and becomes a liquid back state in the refrigeration cycle apparatus using the electric expansion valve. Is to be able to do.

[0014]

According to a first aspect of the present invention, in a refrigeration cycle apparatus in which a compressor, a condenser, a temperature expansion valve and an evaporator are sequentially connected, refrigerant is sucked from the evaporator to the compressor. The line is branched into a main line and a bypass line, a refrigerant heating heater and a temperature-sensing cylinder for a temperature type expansion valve located downstream of the heater are provided in the bypass line, and the discharge temperature of the compressor is equal to or higher than a certain level. It is characterized by comprising a control device for causing the heater to perform a heating input when the temperature rises.

In a refrigeration cycle apparatus in which a compressor, a condenser, an electric expansion valve and an evaporator are connected, a refrigerant suction line from the evaporator to the compressor is a main line and a bypass line. In addition to branching to, the bypass line is provided with a heater for refrigerant heating and a suction temperature detector located downstream thereof, and the superheat is constant so that the superheat becomes constant based on the detection value of the suction temperature detector. It is characterized in that a control device for controlling the opening and closing of the expansion valve is provided.

[0016]

The operation according to the invention of claim 1 is as follows.

That is, when the refrigeration cycle is driven under normal standard conditions, the refrigerant is not heated by the heater, and the refrigerant flows through both the main line of the suction line and the bypass line. Refrigerant control similar to that of the refrigeration cycle device described above is performed, and efficient operation without liquid back is performed.

On the other hand, when the discharge temperature of the compressor rises above a certain level under the condition that the condensation temperature becomes high, for example, the load of the condenser becomes excessively large, the heater of the bypass line is controlled by the controller. No heating input is made. Due to this refrigerant heating, superheat increases in the bypass line, so the thermal expansion valve operates in the opening direction,
Control is performed in the direction of reducing the superheat, and the main line of the suction line is automatically adjusted so that the liquid discharge operation is performed and the discharge temperature of the compressor is lowered.

Therefore, according to the first aspect of the invention, in the refrigeration cycle apparatus using the temperature type expansion valve, the discharge temperature can be lowered even when the condenser load becomes excessive. Further, the discharge temperature can be kept constant by controlling the input to the heater.

The operation according to the invention of claim 2 is as follows.

That is, in the present invention, the suction temperature detector provided in the bypass line is input to the control device, the superheat amount is obtained from the difference from the saturation temperature, and the obtained superheat amount is compared with the set value. The electric expansion valve is controlled by the difference (deviation) due to the above, and the superheat is controlled to be constant at all times.

Then, in this state, if the superheat at the outlet of the evaporator becomes small due to some disturbance (such as a rapid decrease in the air volume of the fan of the evaporator) and the liquid becomes in the liquid back state, this liquid back A part of the refrigerant in the state (wet state) is diverted to the bypass line and heated by the heater, so that the wet state changes to the dry state.

Due to such a change in dryness, the amount of superheat in the bypass line increases, and the rise in temperature due to this is detected by the suction temperature detector, and the controller corrects the opening of the electric expansion valve. Is.

Therefore, according to the second aspect of the present invention, in the refrigeration cycle apparatus using the electric expansion valve, the valve opening can be controlled even when the superheat becomes small due to disturbance or the like and the liquid is in the back state. Like

[0025]

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

1 and 2 show a first embodiment.

In this embodiment, as shown in FIG. 1, a compressor 31, a condenser 32, a thermal expansion valve 33 and an evaporator 34.
Are sequentially connected by a refrigerant pipe 35, thereby forming a closed refrigeration cycle.

The refrigerant suction line 35a from the evaporator 32 to the compressor 31 is branched into a main line 36 and a bypass line 37.

In the bypass line 37, from the upstream side,
A throttle mechanism 38, an electric heater 39 for heating the refrigerant, and a temperature-sensitive expansion valve temperature-sensitive tube 40 are provided. The temperature sensing cylinder 40 is connected to the thermal expansion valve 33 via a capillary tube 40a, and the line 37 and the thermal expansion valve 33 are connected to each other by a pressure equalizing pipe 41.

The heater 39 has a unit structure including a heat transfer coil which covers the pipe of the bypass line 37.
The controller 42 controls heating input, that is, energization.

The controller 42 has an input controller 43 and a microcomputer 44, and the compressor 3
The temperature detection signal from the discharge temperature detector 45 provided in the first discharge line 35b is input to the input controller 43, and the microcomputer 44 performs calculation for input control to the heater 39.

FIG. 2 illustrates the relationship between the heater input level and the discharge temperature in the controller 42. As shown in the figure, the heater input is stepwise increased as the discharge temperature rises. For example, the input becomes maximum when the discharge temperature is 105 ° C. or higher, and the input is 0 when the discharge temperature is 95 ° C. or lower. Is set to be

Next, the operation will be described.

During cycle operation under standard conditions,
The discharge temperature is set to 95 ° C or lower, and the heater 39 is turned off.
To be in a state. Further, the temperature type expansion valve 33 is controlled and operated by setting the superheat of the bypass line 36 to, for example, 5 deg. In this case, since the heater is off,
Similarly, in the main line 36, superheat is controlled to 5 deg, and efficient operation without liquid back is performed.

On the other hand, when the load on the condenser 32 becomes excessive, the condensing temperature rises and the discharge temperature of the compressor 31 also rises. At this time, the control device 42 receives the signal from the discharge temperature detector 45 and controls the input to the heater 39.

When the input to the heater 39 is made, the refrigerant in the bypass line 37 is heated, and the superheat becomes a value larger than 5 deg when the heater is off. This allows
The temperature type expansion valve 33 performs a control operation in a direction in which the superheat becomes smaller, that is, a control operation in a direction in which the valve opening degree is expanded, via the temperature sensing cylinder 40. Therefore, the superheat of the bypass line 37 returns to the original 5 deg, but in the main line 36, the superheat is controlled to 5 deg or less, and the liquid becomes slightly liquid back.

In this way, when the input is applied to the heater 39 and the bypass line 37 is heated, the suction line 35a.
The superheat becomes smaller, and the suction line 35a becomes liquid back, and the rise in the discharge temperature is suppressed. The heater input is set so as to increase according to the height of the discharge temperature.

As described above, according to the configuration of the embodiment, the superheat can be efficiently operated at 5 deg under the standard load, while the liquid back-up is performed when the load is heavy and the discharge temperature rises. The discharge temperature becomes 1
It can be suppressed to around 00 ° C.

3 and 4 show a second embodiment.

This embodiment relates to a split type heat pump type air conditioner, and as shown in FIG.
The compressor 51, the indoor heat exchanger 52, the electric expansion valve 53, and the outdoor heat exchanger 54 are sequentially connected by a refrigerant pipe 55, and a four-way valve 56 is arranged in a suction line 55a and a discharge line 55b of the compressor 51. The heat pump type refrigeration cycle is constituted by this. The suction line 55 a of the compressor 51 is provided with a refrigerant suction temperature detector 57.

Further, in the arrangement where the upstream and downstream parts of the expansion valve of the refrigerant pipe 55 and the suction line 55a of the compressor 51 are connected,
Saturation temperature detection circuit 59 having a capillary tube 58
The saturation temperature detecting circuit 59 is provided with a saturation temperature detector 60.

Then, the suction temperature detector 57 detects the superheat in the suction line 55a, and the saturation temperature detector 60 detects the saturation temperature, which are input to the control device 61 to obtain the superheat amount. At the same time, the correction amount of the valve opening is obtained according to the difference (deviation) between the obtained superheat amount and the set value,
As a result, the motor 53a of the electric expansion valve 53 is controlled.

In this system, the refrigerant suction line 55a to the compressor 51 is composed of a main line 62 and a bypass line 6.
A refrigerant heating heater 65 is provided in the bypass line 63 via a throttle mechanism 64. The heater 65 is controlled by the heater control device 66 so that the heating input is performed when the compressor suction temperature becomes lower than a certain value. The suction temperature detector 57 is arranged downstream of the heater 65 in the bypass line 63.

Further, the control device 61 is configured to have a microcomputer for controlling the opening and closing of the electric expansion valve 53 so that the superheat becomes constant based on the detection value of the suction temperature detector 57.

FIG. 4 is a flow chart showing the operation of the control device 61, and the electric expansion valve 53 is controlled and operated in the following procedure.

Basically, based on the signals from the suction temperature detector 57 of the bypass line 63 and the saturation temperature detector 60 of the saturation temperature detection circuit 59, the microcomputer of the control unit 61 performs the calculation, and the electric The expansion valve 53 is controlled.

First, the superheat SH (= Ta-Tb) of the bypass line 63 is detected from the difference between the suction temperature detector 57 and the saturation temperature detector 60 (a). Ta is the temperature of the bypass line 63, and Tb is the saturation temperature.

Then, the difference (deviation) .DELTA.SH between the set value SHS and the actual superheat SH is obtained by the timer (b) at regular control intervals (for example, 1 minute) (c).

The opening correction amount ΔPLS (= f (ΔSH)) of the electric expansion valve 53 is obtained from the magnitude of the deviation ΔSH, and the valve control is performed by the signal output (e). After the signal is output, the timer is reset (f).

When the deviation ΔSH is positive (when the superheat is small), the opening of the electric expansion valve 53 is closed, and when the deviation ΔSH is negative (when the superheat is large), the electric drive is performed. The control is performed in the direction of increasing the opening degree of the expansion valve 53. Further, the larger the deviation ΔSH is, the larger the correction amount is controlled.

According to this embodiment, the bypass line 6 is always
Since the superheat of No. 3 is controlled to be constant, the superheat at the outlet of the evaporator (the indoor heat exchanger 52 or the outdoor heat exchanger 54) may be caused by some disturbance (for example, a rapid decrease in the air volume of the fan of the evaporator). Even if the heat becomes small and the liquid back state occurs in some cases, the refrigerant in the liquid back state (wet state) is shunted by the bypass line 63, a part of the refrigerant is heated by the heater 65, and the wet state is dried. become.

Since the amount of superheat in the bypass line 63 increases due to such a change in dryness, the rise in temperature due to this is detected by the suction temperature detector 57, and the controller 61 opens the opening of the electric expansion valve 53. Is to be corrected.

Therefore, in the refrigeration cycle apparatus using the electric expansion valve 53, even when the superheat becomes small due to disturbance or the like and the liquid is in the back state, quick and smooth control is performed to bring the predetermined amount of superheat. Can be returned.

[0054]

As described above, according to the first aspect of the invention,
In the refrigeration cycle apparatus using the temperature type expansion valve, the discharge temperature can be lowered even if the condenser load becomes excessive.

According to the second aspect of the present invention, in the refrigeration cycle apparatus using the electric expansion valve, the valve opening can be controlled even when the superheat becomes small due to disturbance or the like to bring the liquid back state. become.

[Brief description of drawings]

FIG. 1 is a system diagram showing a first embodiment of the present invention.

FIG. 2 is a graph showing an operation in the above embodiment.

FIG. 3 is a system diagram showing a second embodiment of the present invention.

FIG. 4 is a flow chart showing the operation of the second embodiment.
To.

FIG. 5 is a system diagram showing a conventional example.

FIG. 6 is a system diagram showing another conventional example.

[Explanation of symbols]

 31, 51 Compressor 32, (52, 54) Condenser 33 Temperature expansion valve 34 (52, 54) Evaporator 35a, 65a Suction line 36, 62 Main line 37, 63 Bypass line 39, 65 Heater 40 Temperature sensing tube 42, 61 Control device 53 Electric expansion valve 57 Suction temperature detector

Claims (2)

[Claims] 1. A refrigeration cycle apparatus in which a compressor, a condenser, a temperature expansion valve and an evaporator are sequentially connected, and a refrigerant suction line from the evaporator to the compressor is branched into a main line and a bypass line. Along with this, a refrigerant heating heater and a temperature type expansion valve temperature sensing cylinder located on the downstream side are provided in the bypass line, and a heating input is input to the heater when the discharge temperature of the compressor rises above a certain level. A refrigeration cycle apparatus comprising a control device for performing the above. 2. A refrigeration cycle apparatus in which a compressor, a condenser, an electric expansion valve and an evaporator are connected, and a refrigerant suction line from the evaporator to the compressor is branched into a main line and a bypass line, A refrigerant heating heater and a suction temperature detector located downstream thereof are provided in the bypass line, and the electric expansion valve is controlled to open and close so that superheat becomes constant based on the detection value of the suction temperature detector. A refrigeration cycle apparatus comprising a control device for controlling the refrigeration cycle.