JPH0727057A - Liquid back alarm output method and device - Google Patents

Abstract

(57) [Summary] [Purpose] To prevent reaction from a momentary decrease in superheat caused by a small amount of refrigerant liquid such as oil mist. [Structure] The suction pressure P is applied to the evaporator 1 outlet pipe 3 of the compressor 2.
1 and the sensors 4 and 5 for detecting the intake refrigerant temperature Ss are incorporated, and the signals of the respective sensors are input into the controller C, and P1
Is converted to a refrigerant saturation temperature S1 and a superheat degree calculation unit 6 for calculating and measuring the superheat degree is provided and connected to the calculation unit 6 to generate a liquid back from the preset liquid back determination superheat degree RS and the measured superheat degree MS. A liquid back determination unit 7 for determining is provided, and when the measured superheat degree is lower than the liquid back determination superheat degree, an alarm output grace time is set by the integral time timer 8 according to the degree, and the refrigerant supply pipe 10 is output by the alarm signal output. The operation section 9 of the external output relay 12 for operating the refrigerant liquid supply solenoid valve 11 and the like provided in the above is provided.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention issues a liquid back alarm when a liquid back occurs in a suction line from an evaporator outlet to a compressor suction port in a refrigeration or heat pump device, and a liquid back alarm for stopping refrigerant liquid supply. The present invention relates to an output method and its device.

[0002]

2. Description of the Related Art In the field of refrigeration or heat pump devices, the liquid back phenomenon in which the refrigerant liquid reaches the suction line due to over-injection of the refrigerant liquid to the evaporator causes the suction temperature to drop to near the suction saturation temperature, resulting in compression. It had a bad effect such as damaging the machine.

Conventionally, in order to avoid these accidents, regardless of the suction pressure of the compressor, only the suction temperature is monitored, and when the temperature falls below a set temperature, it is judged that liquid back has occurred and an alarm is output. Was there.

Alternatively, the superheat degree of the difference between the suction saturation temperature of the suction line (evaporator outlet pipe) and the suction refrigerant temperature is captured, and when the temperature becomes lower than the set superheat degree, it is judged that liquid back has occurred and an alarm is output. Was.

Then, a method of sounding an alarm bell, closing the refrigerant liquid supply solenoid valve, or making an emergency stop of the compressor by the output of the liquid back alarm has been adopted, and there have been devices for implementing those methods.

[0006]

In the conventional method and apparatus, since the suction pressure (suction saturation temperature) in the suction line (evaporator outlet pipe) of the compressor is not incorporated, the degree of superheat actually decreased. I could not judge.

There is also a device having a built-in function of comparing with the degree of superheat, but it is used only for outputting an alarm based on the information that the degree of superheat is below a set degree of superheat.

Therefore, for example, the apparatus reacts to an instantaneous decrease in superheat due to a small amount of refrigerant liquid such as oil mist, and there is a drawback that an alarm is output.

It is an object of the present invention to provide a liquid back alarm output method and device for preventing reaction with respect to an instantaneous decrease in superheat caused by a small amount of refrigerant liquid such as oil mist.

[0010]

In order to achieve the above object, the present invention detects a refrigerant suction temperature and a suction pressure in a suction line (evaporator outlet pipe) from an evaporator to a compressor. Incorporate a sensor.

A signal from each sensor is inputted into the controller, a suction pressure is converted into a refrigerant saturation temperature, and a superheat degree calculating section for measuring the superheat degree with the suction refrigerant temperature is provided.

The controller is provided with a liquid back determination unit which is connected to the superheat degree calculation unit and determines the occurrence of the liquid back from the preset liquid back determination superheat degree and the measured superheat degree in the calculation unit.

From the time when the measured superheat degree in the superheat degree calculation section becomes lower than the liquid back judgment superheat degree set in advance in the liquid back judgment section, the integration time type timer provided in the liquid back judgment section measures the measured superheat degree. Set the alarm output delay time according to the degree.

An operation unit for an external output relay, which is connected to the liquid back determination unit and operates a refrigerant supply solenoid valve or the like interposed in the refrigerant supply pipe of the evaporator according to the command, is provided in the controller.

[0015]

The signals of the sensor 4 for detecting the suction pressure and the sensor 5 for detecting the suction refrigerant temperature provided in the suction line 3 from the evaporator 1 to the compressor 2 are input to the superheat calculation section 6 to calculate the superheat. And measure.

Then, the liquid back determination unit 7 connected to the superheat degree calculation unit 6 compares the measured superheat degree input from the calculation unit 6 with the liquid back determination superheat degree preset in the determination unit 7.

In the liquid back judgment unit 7, an alarm output delay time is set in accordance with the measured superheat degree, and the integral time type timer 8 is activated when the measured superheat degree becomes smaller than the set superheat degree.

The integral time type timer 8 times up after a time corresponding to the degree of the measured degree of superheat, oil mist,
It is possible to prevent malfunction of the liquid back alarm without reacting to a momentary decrease in superheat caused by the arrival of a minute refrigerant liquid.

The operation unit 9 receives the liquid back alarm from the liquid back determination unit 7, issues an external output signal, and operates the external output relay 12 via the built-in relay 9a.

The refrigerant supply pipe 10 on the inlet side of the evaporator 1
To close the refrigerant supply solenoid valve 11 interposed therein, sound an alarm buzzer, and stop the compressor 2.

[0021]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A detailed description will be given of the accompanying drawings showing an example of the embodiment of the present invention.

FIG. 1 shows the outline of the liquid back alarm output device of the present invention, FIG. 2 shows the relationship between the alarm output point of an integral time type timer and its elapsed time, and FIG. 3 shows the same compressor. It shows an example in which two sets of evaporation systems are connected.

In FIG. 1, reference numeral 1 is an evaporator, which condenses a high temperature and high pressure refrigerant gas compressed by a compressor 2 by a condenser 14,
It is stored as a high-pressure liquid in the liquid receiver 15, is supplied as a low-pressure refrigerant liquid by the liquid injection valve 16 via the refrigerant supply pipe 10, and is heat-exchanged with air or the like to be evaporated.

Reference numeral 3 denotes an outlet pipe of the evaporator 1, which supplies the evaporated refrigerant gas to the suction port 2a of the compressor 2 and constitutes a suction line of the compressor 2.

Reference numeral 4 denotes a pressure sensor, which is installed in the pipe 3 of the suction line and detects the suction pressure P1 to the compressor 2. The pressure from the pressure sensor 4 is saturated with the refrigerant in the superheat calculation unit 6 described later. Converted to temperature S1.

Reference numeral 5 is a temperature sensor for detecting the suction refrigerant temperature Ss, which is installed in the pipe 3 of the suction line 3 and detects the temperature of the refrigerant sucked into the compressor 2.

Reference numeral 6 denotes a superheat calculation unit provided in the controller C, which inputs the suction refrigerant temperature Ss from the temperature sensor 5 and the refrigerant saturation temperature S1 from the pressure sensor 4, and calculates the difference (S
The superheat degree is calculated as s-S1) and used as the measured superheat degree MS.

A liquid back determination unit 7 is provided in the controller C, and sets the superheat degree at which liquid back occurs in advance as the liquid back determination superheat degree RS.

Then, a set time T of an integration time type timer 8 which will be described later and operates when the MS becomes smaller than RS.
It has a built-in circuit that sets e according to the degree of measurement superheat MS.

Numeral 8 is an integral time type timer, which starts its operation when MS <RS and the integrated area Tm × MS obtained by the measurement interval Tm and MS is an area F = RS × preset by RS and Te. When Te is exceeded, it is judged as liquid back and a signal is emitted.

In FIG. 2, the MS in the integration time type timer 8 is RS.
It is explanatory drawing which shows the relationship between the alarm signal output point and elapsed time, when it further decreases and the state continues.

FIG. 2A shows the case where Ss sharply drops to MS = 0, and FIG. 2B shows the case where MS drops to half of RS.

An operation unit 9 is provided in the controller C by being connected to the liquid back determination unit 7, and operates an external output relay 12 to be described later via a relay 9a.

Reference numeral 11 denotes a refrigerant liquid supply solenoid valve provided in front of the liquid injection valve 16 of the refrigerant liquid supply pipe 10 on the inlet side of the evaporator 1, which is connected to the external output relay 12 by an operation line 13 to receive an alarm signal. Shut off the supply of refrigerant.

An external output relay 12 receives a liquid back determination signal from the liquid back determination unit 7 and sounds an alarm buzzer or closes the refrigerant liquid supply solenoid valve 11 via the operation unit 9.

FIG. 3 shows two sets of evaporation systems in the same compressor 2. As in FIG. 1, the high-temperature and high-pressure refrigerant gas discharged from the compressor 2 is condensed by the condenser 14 and received as high-pressure liquid. Store in the liquid container 15.

Then, from the liquid receiver 15 through the branch pipes 10a and 10b of the refrigerant liquid supply pipe 10, the liquid injection valves 16a and 16b supply the low temperature and low pressure refrigerant liquid to the evaporators 1a and 1b.

The refrigerant gas that has exchanged heat with the evaporators 1a and 1b passes through the outlet pipes 3a and 3b, respectively, and then the pipes 3a and 3b.
The suction port 2a of the compressor 2 from the general suction pipe 3c which bundles 3b
Circulates to.

Temperature sensors 5a and 5b for detecting the intake refrigerant temperature Ss are provided in the outlet pipes 3a and 3b, respectively, and are connected to the superheat degree calculation unit 6 provided in the controller C for each of the evaporators 1a and 1b.

A pressure sensor 4 for detecting the suction pressure to the compressor 2 is provided in the general suction pipe 3c, and is connected to a superheat calculation section 6 similarly equipped.

Further, in the present embodiment, the temperature sensor 5c for detecting the suction refrigerant temperature (Ss) is provided in the general suction pipe 3c, but the suction pressures in the outlet pipes 3a, 3b and the general suction pipe 3c are the same, and are installed. The location can be selected as appropriate.

Further, the operation is such that the temperature and pressure information supplied via the temperature sensor 5a attached to the pipe 3a and the pressure sensor 4 of the general suction pipe 3c are saturated by the superheat calculation unit 6 of the evaporator 1a of the controller C. The superheat degree MSa is calculated by converting the temperature S1a.

This superheat degree MSa is the controller C
Liquid back judgment superheat degree RS of the liquid back judgment unit 7 installed in
When it becomes smaller, the integral time type timer 8 in the controller C starts to operate.

At this time, if MSa does not rise and the timer 8 times out, the judgment unit 7 judges that the liquid is back,
The liquid back alarm signal is output from the operation unit 9 of each of the evaporators 1a and 1b in the controller C through the operation line 13a, the liquid supply solenoid valve 11a is closed, and the solenoid valve 13a is opened after the liquid back is recovered. be able to.

Further, the temperature sensor 5 attached to the pipe 3b
In the case of b, the pressure is converted into the saturation temperature S1b by the superheat calculation unit 6 of the evaporator 1b as in the temperature sensor 5a, and the superheat M is calculated.
Sb is calculated, and it becomes possible to operate the liquid supply solenoid valve 11b via the operation line 13b as described above.

The general suction pipe 3 of the suction port 2a of the compressor 2
When it is determined by the temperature sensor 5c and the pressure sensor 4 attached inside c that the liquid is the same as described above, the operation unit 9
The compressor 2 can be automatically stopped using the alarm output signal output from the control line 13c through the operation line 13c, and the automatic restart can be performed when the liquid bag is recovered.

[0047]

According to the present invention, the compressor 2 is constructed as described above.
Suction pressure (refrigerant saturation temperature S1), suction refrigerant temperature Ss
The calculated superheat degree MS is calculated by the following, and when this MS becomes smaller than the preset liquid back judgment superheat degree RS, it is judged that liquid back occurs, and the integral time type timer 8 is activated, and M
The alarm output delay time is set according to the degree of S.

Since the liquid back alarm signal is output after the timer 8 has timed out, it does not react to an instantaneous decrease in superheat due to the arrival of oil mist or a small amount of refrigerant liquid, preventing malfunction of the liquid back alarm. Therefore, the stability and reliability of this type of device can be significantly improved.

[Brief description of drawings]

FIG. 1 is a principal block wiring diagram showing an outline of a liquid back alarm output device of the present invention.

FIG. 2 is an explanatory diagram showing a relationship between an alarm output point of an integration time type timer and its elapsed time, where A is the case where the suction refrigerant temperature is drastically lowered and the measured superheat degree is 0, and B is the measurement. This is the case where the superheat degree has dropped to half of the liquid back judgment superheat degree.

FIG. 3 is a schematic block wiring diagram showing an embodiment in which two sets of evaporation systems are connected to the same compressor.

[Explanation of symbols]

 1,1a, 1b Evaporator 2 Compressor 2a Suction port 3,3a, 3b Outlet pipe 3c General suction pipe 4 Pressure sensor 5,5a, 5b, 5c Temperature sensor 6 Superheat calculation unit 7 Liquid back judgment unit 8 Integration time type Timer 9 Operation part 9a Relay 10 Refrigerant liquid supply pipe 10a, 10b Branch pipe 11, 11a, 11b Refrigerant liquid supply solenoid valve 12 External output relay 13, 13a, 13b, 13c Operation line 14 Condenser 15 Liquid receiver 16, 16a , 16b Liquid injection valve C controller F Area MS, MSa, MSb Measured superheat degree P1 Intake refrigerant pressure RS Liquid back judgment superheat degree S1, S1a, S1b Refrigerant saturation temperature Ss Intake refrigerant temperature Te set time Tm Measurement interval

Claims (2)

[Claims] 1. A superheat calculation unit in a controller inputs signals from a sensor for detecting a suction pressure attached to a suction line from an evaporator to a compressor and a sensor for detecting a suction refrigerant temperature to measure the superheat. Then, compare with the liquid back judgment superheat degree set in advance by the liquid back judgment unit connected to the superheat degree calculation unit, set the alarm output grace time according to the measured superheat degree,
A liquid back alarm output method comprising: operating an integration time type timer from a time point when a measured superheat degree becomes smaller than the preset superheat degree, and outputting an alarm after a time corresponding to the measured superheat degree. 2. A sensor for detecting suction pressure and a sensor for detecting suction refrigerant temperature are respectively provided in suction lines from the evaporator to the compressor, and a controller for inputting a signal from each sensor is provided, and the controller is provided in the controller. A superheat degree calculation unit for receiving a signal to measure the superheat degree is provided, and a liquid back determination unit for determining the liquid back is provided based on a preset liquid back determination superheat degree and the measured superheat degree from the calculation unit. In addition, an integral time type timer is provided as an alarm output delay time setting circuit, and an external output relay operation unit for operating the refrigerant liquid supply solenoid valve etc. interposed in the refrigerant liquid supply pipe of the evaporator in response to a command from the liquid back determination unit is installed. Liquid back alarm output device characterized in that