JP2000356388A - Air conditioner for railroad vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent dew formation on the controller of a motor expansion valve by preventing a leakage fault due to adhesion of condensate from an evaporator to the coil part of the motor expansion valve and suppressing generation of heat by air cooling the motor expansion valve. SOLUTION: A motor expansion valve 5 is positioned between the air inlet of an indoor fan and a partition wall facing the air inlet and the coil part of the motor expansion valve 5 is cooled with air cooled through evaporators 4a, 4b. Even if water drops are flown from the fin part by the air sucked through indoor fans 3a, 3b, the water drops do not adhere to the coil part of the motor expansion valve 5. The controller 10 for the motor expansion valve 5 is fixed in return air atmosphere in the vicinity of the return opening of an indoor unit chamber and cooled with humidified air in a vehicle. Inlet refrigerant temperatures are detected for a plurality of evaporators and the average temperature is employed as an inlet refrigerant temperature for controlling the opening of the motor expansion valve. Consequently, lack of uniformity in the inlet refrigerant temperature can be corrected for a plurality of evaporators.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an air conditioner for a railway vehicle, and more particularly to an electric expansion valve of an air conditioner for controlling the degree of superheat of an evaporator by an electric expansion valve, a method of mounting the controller and a method of controlling the electric expansion valve. About.

[0002]

2. Description of the Related Art Conventionally, a capillary tube is generally used as a decompression device in a railway vehicle air conditioner.
There is no air conditioner using an electric expansion valve. Although it is commonly used in many other models for home and building air conditioning, there is no air conditioner with an electric expansion valve attached to the air outlet side of the indoor heat exchanger. It is attached. Therefore, there was no need to consider the adhesion of condensed water.

[0003] However, in order to simplify the piping work, it is sometimes necessary to attach an electric expansion valve to the air outlet side of the evaporator in order to simplify the piping work, and it is necessary to prevent adhesion of condensed water. there were. Although the lead-out portion of the electric expansion valve has a waterproof structure, it is better to prevent moisture from adhering to ensure long-term durability. Moreover, a method that does not cost much is desired. In addition, since the life of the motor is extended as the coil temperature is lower, it is better to cool the coil portion by air.

When the controller of the electric expansion valve is mounted near the electric expansion valve, the length of the lead wire can be shortened.
Less susceptible to noise. In addition, the connection with the temperature sensor attached to the piping at the entrance and exit of the evaporator is easy. However, since the temperature of the indoor unit room is low, there is a concern that the insulation of electronic components may be poor due to condensation.

In order to control the degree of opening of the electric expansion valve, it is necessary to detect the temperature difference between the inlet and the outlet of the evaporator. However, when the refrigerant is diverted from the electric expansion valve to two evaporators to flow the refrigerant, a temperature sensor is required. Mounting position is important. Normally, the distributor attached to the inlet of the evaporator has a slight resistance in order to divide the refrigerant evenly, and a pressure drop also occurs in this portion. If the inlet refrigerant temperatures of the two evaporators are almost the same, the temperature at one of the representative points may be measured, but the air volume sucked from the return port and passing through the two evaporators is made equal. It is difficult and a slight temperature difference occurs.
Therefore, the detected temperature differs depending on the position where the temperature sensor is attached.

[0006]

SUMMARY OF THE INVENTION In addition to preventing a leakage fault caused by condensed water of an evaporator adhered to an electric expansion valve,
The electric expansion valve is air-cooled to suppress heat generation. In addition, dew condensation on the controller of the electric expansion valve is prevented. Further, in a refrigeration cycle in which a refrigerant is diverted from an electric expansion valve to a plurality of evaporators to flow a refrigerant, a method of detecting a refrigerant temperature at an inlet of the evaporator is defined.

[0007]

A motor-operated expansion valve is provided between a suction port of an indoor fan and a partition wall facing the suction port, and a coil portion of the motor-operated expansion valve is cooled by air cooled by an evaporator. I do. Even if water drops fly from the fin portion due to the wind sucked by the indoor fan, they do not adhere to the coil portion of the electric expansion valve.

The controller of the electric expansion valve is mounted in a return air atmosphere near the return port of the indoor unit room, and the controller is air-cooled with dehumidified air in the vehicle.

[0009] The inlet refrigerant temperatures of the plurality of evaporators are detected, and the average temperature is set as the inlet refrigerant temperature for controlling the opening of the electric expansion valve.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below in detail with reference to the embodiments shown in FIGS. Here, FIG. 1 is a plan view showing a state in which a cover of an air conditioner mounted on a roof of a vehicle is removed, FIG. 2 is a refrigeration cycle system diagram of FIG. 1, and FIG. 3 is a flowchart of electric expansion valve control.

As shown in FIG. 1, the air conditioner has an indoor unit room at the center, an outdoor unit room on the right side, and a compressor room on the left side. In the outdoor unit room, there is an outdoor fan 1 in the center
And the condensers 2a and 2b are arranged before and after.
The indoor units have indoor fans 3a and 3b and evaporators 4a and 4b.
The electric expansion valve 5 is mounted between the suction ports of the indoor fans 3a and 3b and a partition wall facing the suction ports. Here, 6a and 6b are return ports for taking in the air inside the vehicle. The switchboard 7 is installed near the return port adjacent to the compressor room, and the controller 1 of the electric expansion valve is provided.
Numeral 0 is attached to the frame near the return port located on the opposite side of the switchboard 7. A compressor 8 and an accumulator 9 are installed in the compressor room.

Next, the refrigeration cycle will be described with reference to FIGS. The high-temperature, high-pressure gas refrigerant discharged from the compressor 8 is supplied to the condenser 2a. At 2b, the air is cooled by the outside air blown by the outdoor fan 1 to become a medium-temperature / high-pressure liquid refrigerant. The liquid refrigerant is decompressed by the electric expansion valve 5 to be in a two-phase state of a low-temperature, low-pressure liquid and gas, and is heat-exchanged with the air in the vehicle by the evaporators 4a and 4b to become a gas refrigerant. The gas refrigerant returns to the compressor 8 through the accumulator 9.

The moisture in the air that has been cooled and condensed by the evaporators 4a and 4b usually accumulates in the form of a film on the surface of the fin, and when it develops to a certain size, it flows downward by its own weight. However, when the air conditioner has been used for many years, dust adheres to the fins, causing clogging, and the wind speed increases between fins where no clogging occurs. For this reason, a phenomenon in which the condensed water droplets are blown off by the wind toward the indoor fans 3a and 3b sometimes occurs. This phenomenon can be prevented beforehand if the evaporators 4a and 4b are cleaned at regular intervals, but it is necessary to design the structure of the apparatus in consideration of the case where cleaning is not performed.

The air in the vehicle sucked from the return ports 6a and 6b is cooled by heat exchange with the refrigerant passing through the pipes in the evaporators 4a and 4b, and the moisture in the air condenses and accumulates in the lower drain receiver. The air is discharged from the drain pipes 11a and 11b to the outside of the machine. If the fins are clogged, the evaporators 4a, 4b
Even if water drops fly from the inside, they fly toward the suction ports of the indoor fans 3a and 3b. Therefore, if the electric expansion valve 5 is mounted between the suction port and the facing partition wall, the adhesion of water drops can be completely prevented. it can. Further, since the temperature of the coil portion of the electric expansion valve 5 is always higher than the ambient temperature due to heat generation, there is no dew condensation.

The controller 10 of the electric expansion valve 5 is mounted on a frame near the return port adjacent to the compressor room. Since the temperature near the return port is normally kept at the same temperature as the temperature inside the vehicle, the casing of the controller 10 does not condense the air and moisture in the atmosphere.

Next, a control method of the electric expansion valve will be described with reference to FIGS. The temperature of the refrigerant at the inlet of the evaporator required to control the opening of the electric expansion valve 5 is detected by temperature sensors 13a and 13b fixed in contact with the surfaces of the outlet pipes of the distributors 12a and 12b. The temperature is detected by a temperature sensor 14 fixed in contact with the surface. The refrigerant temperature at the inlet of the evaporator used for controlling the electric expansion valve 5 is an average value of the temperature sensors 13a and 13b, and the degree of superheat of the refrigerant at the evaporators 4a and 4b is obtained from the temperature difference from the refrigerant temperature at the outlet. The flow up to this is the flow shown from F1 to F4.

The difference between the refrigerant temperature at the inlet and the outlet of the evaporator obtained above is compared with the set temperature difference. If the difference is the same, the current opening is maintained. If the difference is different, the opening is adjusted. Specifically, when the set temperature difference is smaller, the electric expansion valve is opened, and when the set temperature difference is larger, the electric expansion valve is throttled. The flow up to this point is the flow from F5 to F6.

The method of mounting the electric expansion valve 5 and the controller 10 of the electric expansion valve and the method of controlling the electric expansion valve have been described above. However, the configuration of the air conditioner is not limited to the present embodiment, but may be variously changed. May be.

[0019]

As described above, according to the present invention, water droplets blown from the evaporator do not adhere to the electric expansion valve, and it is possible to prevent a leakage fault due to insulation deterioration of the coil lead wire. In addition, the coil portion of the electric expansion valve is air-cooled by the cooling air of the evaporator, so that the coil life of the electric expansion valve is improved. Further, dew condensation on the controller of the electric expansion valve can be prevented. Further, in the case where the refrigerant is diverted from one electric expansion valve to a plurality of evaporators, it is possible to correct unevenness in the refrigerant temperatures at the inlets of the plurality of evaporators.

[Brief description of the drawings]

FIG. 1 is a plan view of an air conditioner.

FIG. 2 is a refrigeration cycle system diagram.

FIG. 3 is a flowchart of electric expansion valve control.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Outdoor fan, 2a, 2b ... Condenser, 3a, 3b ... Indoor fan, 4a, 4b ... Evaporator, 5 ... Electric expansion valve, 8 ...
Compressor, 9: Accumulator, 10: Controller for electric expansion valve

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Daisuke Akiramaru 794 Higashi-Toyoi, Katsumatsu-shi, Yamaguchi Prefecture F-term in the Kasado Plant of Hitachi, Ltd. 3L060 AA01 AA08 CC04 EE09

Claims (3)

[Claims] 1. An air conditioner for a railway vehicle, wherein an electric expansion valve is installed between a suction port of an indoor fan and a partition wall facing the suction port. 2. The air conditioner for a railway vehicle according to claim 1, wherein the controller of the electric expansion valve is installed in a return air atmosphere near the return port. 3. An air conditioner in which a refrigerant is diverted from one electric expansion valve to a plurality of evaporators, and the air in the vehicle is cooled by the plurality of evaporators. A temperature sensor is mounted, and the opening degree of the electric expansion valve is controlled by a temperature difference between an average detected temperature of each temperature sensor and a detected temperature of the temperature sensor mounted on the collecting pipe at the evaporator outlet. Of controlling a railway vehicle air conditioner.