JP2005315550A - Refrigerant flow control device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To simplify a device by integrally constructing and incorporating all structural elements for basic control of an electronic expansion valve in a same housing while solving the problems that the energy saving control of a refrigerator or an air-conditioner depends on a degree of superheating refrigerant, the structural elements required for controlling the degree of superheating the refrigerant currently use combination of products made by different manufacturers to preclude complete control with control parameters different each time, and piping and wiring work is complicated at an installation site for the refrigerator/air-conditioner. <P>SOLUTION: The device executes the control of the degree of superheating of the refrigerant with the control of a closed loop in the housing. An electronic control part is wired with simple conductors of a power line and a serial line. Thus, communication can be carried out between the electronic control part and an external device through the power line and the serial line. Operation in coordination with an external refrigerator/air-conditioner can also be performed through a serial communication line. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

Detailed Description of the Invention

Technical field belonging to the invention

  The present invention relates to a refrigerant flow rate control device that performs expansion valve control drive incorporated in a refrigeration / air conditioning system. Since the period for which cooling is required is expanding in the center of a large building, the present invention is applicable to air-conditioning refrigerators.

Recently, global energy conservation has been screamed, and the reduction of CO ₂ emissions has become a major social problem. In such an environment, energy-saving operation of refrigeration / air conditioners with a large number of operations is an important issue.
In response to changes in the outside air temperature in the morning and noon and seasonal changes, optimum control of the refrigeration air conditioner that maximizes the coefficient of performance indicating the energy saving standard, that is, driving the refrigerator with minimum power consumption is required. It has been.

In recent years, in order to reduce the power consumption of a refrigerator, it has been emphasized that the refrigerant is prevented from being sucked and is operated at a minimum refrigerant superheat degree.
As a specific means, the degree of superheat is accurately detected from the sensor signal and the required degree of superheat is maintained even if the cooling load fluctuates, and the valve opening of the expansion valve is driven by an electric motor such as a stepping motor. This type of linear electric expansion valve is being put into practical use.

  However, in the refrigeration and air conditioning systems that are currently in practical use, the motorized valve and the control unit are physically separated, and the refrigerant temperature and refrigerant pressure for detecting the degree of superheat are converted into electrical signals via sensors. It is converted and connected to the control unit separately. All of these require installation of complicated piping and wiring using products from different manufacturers at the refrigeration and air-conditioning installation site, reducing reliability due to significant construction costs and incorrect wiring and disconnection. Has occurred.

As an example of a conventional system, FIG. 2 shows an example of a motor operated valve.
The low-pressure refrigerant vapor temperature at the outlet of the evaporator 23 is detected by the thermistor 24, and the electric expansion valve 22 is turned on / off in comparison with the set value, and the flow rate of the low-pressure liquid refrigerant is controlled by PWM control.
Since the electric expansion valve 22 is turned on and off by a solenoid valve, there is a problem of the life of the valve seat and the like. Moreover, since the low-pressure refrigerant vapor pressure is not detected, there is a drawback that it is difficult to know the exact degree of superheat.

As a second example of a conventional expansion valve, FIG. 3 shows an example of a temperature-sensitive expansion valve, and FIG. 4 shows the structure of a temperature-sensitive expansion valve body. The main body is installed in the middle of the refrigerant pipe connecting the condenser and the evaporator 32, and the temperature sensing unit 33 detects the refrigerant temperature in the evaporator outlet pipe, and particularly when the refrigerant pressure loss inside the evaporator is large, The refrigerant pressure is led to the expansion valve 31 by piping as a pressure equalization.
The temperature sensing unit 33 indicates that the expansion valve 31 is operated when the refrigerant gas temperature at the suction port of the compressor is 0 ° C. by setting the evaporation temperature to −5.6 ° C. and the superheat degree to 5.6 ° C. Yes.

  Recently, since refrigerators for refrigeration are operated throughout the year, it is necessary to minimize the degree of superheat at the evaporator outlet in order to minimize the drive energy. That is, in order to reduce the heat transfer efficiency of the evaporator and the compressor driving power, the motor valve and its electronic control are combined to increase the effect.

Problems to be solved by the invention

Problems to be solved by the present invention are as follows.
1. Simplification of wiring and piping for motorized valves By omitting complicated piping and wiring work using products from different manufacturers on the refrigeration / air conditioner installation site, construction costs are reduced by simplifying the work. Improvement of reliability can be expected by eliminating miswiring.

2. Realization of advanced energy-saving control in refrigeration and air-conditioning systems Energy-saving depends on the degree of refrigerant superheat, which can be calculated as a function of the temperature and pressure of the low-pressure refrigerant at the outlet of the evaporator.
The components necessary for controlling the degree of superheating of the refrigerant are currently used in combination with products from different manufacturers, and there are problems in performing complete control, such as different control parameters.

3. Initial start-up of the refrigerator / air conditioner When the refrigerator is started for the first time or after it has been stopped for a long period of time, the inside of the refrigerator is at room temperature. For this reason, the load on the refrigerator driving motor is excessive, and normally the refrigerant flow is temporarily restricted in the intake pipe of the compressor so as to avoid the overload and reach the steady operation. Specific low load starting means is desired.

Means for solving the problem

In the present invention, the above-described problems are rationally solved by the following devices and means.
Conventionally, an electronic expansion valve system is configured by combining separate components. However, according to the present invention, these components can be handled as an integrated macro system component.

1. Simplification by integration of components (1) Simplification by integration of components Previously, complicated piping and wiring work was performed using separate components at the refrigeration / air conditioner installation site. There were many. In the present invention, as shown in FIG. 1, all the components for performing basic electronic expansion valve control are integrated and built in the same housing, so that the apparatus can be greatly simplified.

(2) Simplification of control unit Recently, the integrated circuit is improved in environmental friendliness, and an IC capable of operating at -40 ° C is used. Therefore, the control unit of the refrigerant flow control device is the same as the valve drive unit. It is possible to install in the temperature environment.
For this reason, electronic controllers, such as a microprocessor, FPGA, and ASIC, for realizing advanced energy saving control can be incorporated.

(3) Simplification of wiring and information communication Conventionally, since the components are separate, there is a problem in the wiring between the components. However, according to claim 2 of the present invention, the wiring of the electronic control unit is a power line. And a simple conductor called a serial line. Communication between the electronic control unit and the external device can be performed through the power line and the serial wiring. Through this serial communication line, cooperative operation with an external refrigeration / air conditioner is also possible.
Furthermore, the sensor wiring for acquiring the superheat degree signal can be omitted by incorporating the evaporator inlet and outlet in the apparatus.

2. Realization of advanced energy-saving control All components necessary for refrigerant superheat control: temperature sensor, pressure sensor, electronic control unit, and motor-operated valve are housed in the same housing to constitute a control system. Refrigerant superheat degree control that realizes energy saving using these components can be executed by closed loop control in the housing.
Further, all the characteristics of the constituent elements can be set to optimum parameters, and complete control of the refrigerant superheat can be performed.

3. Initial start-up of refrigeration air conditioner When the refrigeration machine starts up for the first time or after it has been stopped for a long period of time, it detects the power consumption of the compressor drive motor and controls the opening of the motorized valve to avoid overloading It becomes possible to do.

According to the present invention, by constructing each component for energy saving control of refrigeration and air conditioners, which has been conventionally separated, in an integrated structure in the same housing, installation work on site is greatly simplified. Reliability can be improved.
Further, all the components of the energy saving control are integrated in the housing, and efficient energy saving can be realized. For this reason, since it can function as a system component and has excellent portability, it can be easily installed everywhere as an energy-saving control device.
The refrigerant flow control device of the present invention, which is easy to install and excellent in energy saving control, is expected to greatly contribute to the realization of a reduction in social CO ₂ emissions, and its effects and contributions are immeasurable. Expected to be.

An embodiment of the present invention will be described based on an example with reference to the drawings.
FIG. 1 shows a configuration when the refrigerant flow rate control device 1 is installed in a refrigeration / air conditioner.
The refrigerant flow control device 1 is for the high-pressure liquid refrigerant from the receiver 2 to control the flow of the low-pressure liquid refrigerant to the evaporator 3. Basically, it has the same function as the conventional expansion valve shown in FIG.

The function of the valve 14 in FIG. 1 is to control the flow rate of the low-pressure liquid refrigerant so that the degree of superheat at the outlet of the evaporator 3 is maintained at a predetermined value.
In order to detect an accurate degree of superheat, it is necessary to simultaneously measure the pressure and temperature of the low-pressure refrigerant at the evaporator outlet.

In the present invention, in FIG. 1, a pressure sensor 4 and a temperature sensor 5 are provided for detecting the pressure and temperature of the low-pressure refrigerant at the outlet of the evaporator 3, respectively. Signals corresponding to the refrigerant pressure and the refrigerant temperature detected from the two sensors are input to the control unit 6 of the refrigerant flow control device.
Since the type of refrigerant used in the refrigerator is determined in advance, the degree of superheat ΔS can be calculated by the electronic control unit 6 from the parameters and the sensor signal described above. Since the target value ΔS ₀ of the superheat degree is given in advance, the valve opening of the refrigerant flow control device 1 is opened according to the sign of the difference Δ ² (= ΔS−ΔS ₀ ) between the current superheat degree and the target superheat degree. Increase / decrease the degree of feedback control.
The conventional motor-operated valve is wired with a separate conductor from the control unit installed outside the valve.

In the refrigerant flow control device 1, an electronic control unit 6, a stepping motor 13, a pressure sensor 4, and a temperature sensor 5 are mounted together with a valve. This eliminates the need for on-site wiring work, eliminates problems such as erroneous wiring and disconnection, and greatly improves the reliability of the apparatus.
In addition, the connection port 8 for the high-pressure liquid refrigerant, the connection port 9 for the low-pressure refrigerant vapor after decompression, the connection port 10 with the refrigerant pipe connected to the evaporator outlet, and the connection port to the refrigerant suction port of the refrigerant compressor 11 is integrally formed. For this reason, simultaneously with omission of the above-mentioned conducting wire in the field, refrigerant piping becomes easy.

  The control unit 6 is provided with two power lines and a simple conductive line called a serial line. Valve opening, sensor information, various alarm signals, and various constants necessary for monitoring and control can be communicated between the electronic control unit 6 and an external device through serial wiring. Furthermore, communication between the electronic control unit and the external device can be performed through the serial wiring, and cooperative operation with an external refrigeration / air conditioner is also possible.

Next, the operation content of the refrigerant flow control device 1 from the start of the refrigerator to the steady operation will be described. As a result of starting the compressor for the first time, the throttle valve opening degree of the machine part which has been closed until immediately before the operation becomes a predetermined opening degree. The opening degree is set to a higher degree of superheat. This value corresponds to the opening degree that prevents the liquid refrigerant of the compressor from being sucked.
Furthermore, when the refrigerator is started for the first time or after it has been stopped for a long period of time, the power consumption of the compressor drive motor can be detected and the opening of the electronic expansion valve can be controlled to avoid overloading. It becomes possible. In addition, the information of the power consumption of a drive motor can grasp | ascertain the compressor drive motor load of the instantaneous moment by detecting the rotational speed of a normal rotary electric power integrator.

  Next, along with the cooling of the air temperature in the refrigerator, the current superheat degree is calculated by the control unit 6 from the information from the pressure sensor 4 and the temperature sensor 5, and the valve opening degree is adjusted to correspond to the target superheat degree by feedback control. Controlled.

  During cooling, moisture in the air in the refrigerator passing through the evaporator is cooled, which may cause condensation and solidification. At this time, the performance of the evaporator is deteriorated by increasing the resistance of the air flow. Melting and removing the ice on the evaporator fin surface is called defrosting. Since the normal cooling operation stops during the defrosting, the valve opening degree is maintained at a predetermined value until the defrosting is completed in response to the defrost signal. The defrost method includes an electric heater method and a hot gas method in which a high-pressure and high-temperature refrigerant gas from a compressor is directly supplied to an evaporator. The valve opening degree in the defrost is controlled according to the method.

It is a figure which shows the structure integrated in the refrigerating / air-conditioner system of the refrigerant | coolant flow control apparatus. It is a figure which shows the structure of the present electric expansion valve. It is a figure which shows the structure by which the conventional temperature-sensitive type expansion valve was integrated in the refrigerator. It is a figure which shows the structure of the conventional temperature-sensitive type expansion valve main body.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Refrigerant flow control apparatus 2 Receiver 3 Evaporator 4 Pressure sensor 5 Temperature sensor 6 Electronic control part 7 Housing 8 Connection port 9 Connection port 10 Connection port 11 Connection port 12 Conductor 13 Stepping motor 14 Valve 21 Transformer 22 Electric expansion valve 23 Evaporator 24 Thermistor 25 Condenser 26 Discharge Pipe 27 Compressor 28 Suction Pipe 31 Expansion Valve 32 Evaporator 33 Temperature Sensing Part 41 Temperature Drive Part 42 Ball Valve 43 Refrigerant Inlet 44 Refrigerant Outlet 45 Superheat Adjusting Spring 46 Spring Fixing Parts 47 Casing 48 Adjustment cap 49 Adjustment screw 50 Temperature sensor

Claims (4)

  In the refrigerant flow control device 1 incorporated in the refrigeration / air conditioner system in FIG. 1, a valve 14 driven by a stepping motor 13 that can variably control the flow rate of the refrigerant liquid by an electric signal from the electronic control unit 6, A connection port 8 connected to the receiver 2, a connection port 11 connected to the compressor suction port, a connection port 9 to the inlet of the evaporator 3 outside the claims and a connection port 10 connected to the outlet, and A structure in which the pressure sensor 4 and the temperature sensor 5 arranged between the connection port 10 and the connection port 11 are wired to the electronic control unit 6 through the piping in the housing 7 is housed and integrated in the housing 7 respectively. A refrigerant flow rate control device.   The electronic control unit 6 shown in claim 1 has a connector for a lead wire 12 composed of a power supply line for supplying power and a serial wiring for communicating with an external device, and the expansion valve opening, sensor information, various alarm signals, 2. The refrigerant flow rate control device according to claim 1, wherein various constants necessary for control can be communicated between the electronic control unit 6 and an external device through serial wiring.   The energy saving of the refrigeration air conditioner system depends on the refrigerant superheat degree, and the refrigerant superheat degree can be calculated as a function of the temperature and pressure of the refrigerant at the connection port 10. The signals of the temperature sensor 5 and the pressure sensor 4 at the outlet of the evaporator 3 are converted into electric signals and sent to the electronic control unit 6 to open the expansion valve 14 that maintains the minimum refrigerant superheat degree for realizing energy saving. The refrigerant flow rate control device according to claim 1, wherein determining the degree optimally and driving and controlling the stepping motor 13 can be executed in a closed loop by components incorporated in the same housing 7.   In the operation at the start of turning on the power, since the operation of the refrigerator is started from room temperature in the refrigerator, the refrigerant inlet pressure to the compressor becomes excessive, and the compressor drive motor becomes overloaded. As a method for avoiding this, the electric power consumption of the motor is converted into an electric signal, which is input to the electronic control unit 6 through the conducting wire 12 to give an expansion valve opening corresponding to an appropriate initial setting. A refrigerant flow control device to be described.