Air conditioner for railway vehicles

Details Air conditioner for railway vehicles Air conditioner for railway vehicles

1992-05-18

1994-05-31

Wayner, William E.

Automatic temperature and humidity regulation

Motors

Electric

236 1R, 236 91C, G05D 2300

Patent

active

053162145

DESCRIPTION:

BRIEF SUMMARY
BACKGROUND OF THE INVENTION

1. Field of the Invention
The present invention relates to the control of an air conditioner for railway vehicles for maintaining an optimum temperature within the vehicles.
2. Description of the Related Art
Examples of air-cooling railway vehicles using conventional air conditioners will be explained with reference to FIG. 64 schematically showing a train car, the circuit diagrams in FIGS. 65 and 67, the flowcharts of the controlling operation in FIGS. 66 and 68, and FIGS. 69 to 71 schematically showing the concepts of the controlling operation.
FIG. 64 is a schematic view of the structure of a train car equipped with a conventional air conditioner and the flow of data therewithin. This is similar to the structure of a train car equipped with an air conditioner and the flow of data therewithin described in Japanese Utility Model Laid-Open No. Hei 2-41037. In FIG. 64, the reference numeral 1 denotes a train car, 2 an air conditioner mounted on the upper part of the train car 1, 3 a heating/cooling power controller for controlling the heating/cooling power by varying the power of a compressor provided in the air conditioner 2, 4 an air conditioner control unit having a means for determining the heating/cooling power, 5 a control switch portion by which a train operator selects the heating or cooling operation, ON or OFF and sets the target temperature in the car, 6 a temperature detector which is composed of a thermistor or the like so as to detect the temperature of the air returned from the car, 7 a heated/cooled air supply opening and 8 a suction opening for sucking the air from the car.
FIG. 65 is a circuit diagram of the air conditioner 4. The air conditioner 4 is composed of an input circuit 41, a CPU 42, a memory 43 and an output circuit 44. An output from the control switch portion 5 in the train operator's compartment and an output from the temperature detector 6 are input to the input circuit 41. The heating/cooling power controller 3 controls the power of the compressor in accordance with the output of the output circuit 44. The CPU 42 calculates the optimum heating/cooling power, and the result of the calculation is supplied to the output circuit 44.
The operation of the air conditioner 4 will now be explained with reference to FIG. 66. A conventional air cooling device of this type controls the air temperature so as to be the target temperature or in the vicinity thereof while calculating the optimum cooling power from the difference between the temperature of the air to be controlled and the target temperature. This control method is generally called proportional control.
The proportional control method will be explained in the following with reference to the flowchart in FIG. 66. At step F1, the air conditioner 4 of the train is first turned ON by a train operator, and the target temperature T0 is set at step F2. At step F3, a preset time for measuring the temperature is allowed to pass, and the air temperature Tn in the car is detected at step F4. The temperature difference dT between the target temperature T0 and the air temperature Ta in the car is obtained at step F5. At step F6, the optimum cooling power is newly calculated from the temperature difference dT, in accordance with the cooling power chart shown in FIG. 69. When the optimum cooling power is obtained in this way, the cooling power for the current cooling operation is changed at step F7, and the cooling operation is continued at the newly changed cooling power at step F8.
In such proportional control, however, since the cooling operation is conducted at the cooling power determined by the temperature difference between the temperature of the air to be controlled and the target temperature, it is difficult to reach the target temperature depending upon the condition of the load, as shown in FIG. 70 which shows the concept of the controlling operation. For example, even if the cooling power is reduced, the air temperature in the car is sometimes lowered to a temperature lower than the target temperatu

REFERENCES:
patent: 4891953 (1990-01-01), Isono
patent: 5209079 (1993-05-01), Kajino

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