Refrigeration – Automatic control – Refrigeration producer
Reexamination Certificate
1999-06-23
2001-06-26
McDermott, Corrine (Department: 3744)
Refrigeration
Automatic control
Refrigeration producer
C062S159000, C062S196400, C062S197000, C062S210000, C062S228500
Reexamination Certificate
active
06250093
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to an apparatus for air conditioning. Particularly, the present invention pertains to an air conditioning system for vehicles and a compressor used therein.
For example, Japanese Unexamined Patent Publication No. 5-223357 discloses such a vehicle air conditioning system. The air conditioning system includes a main heater and a cooler. The main heater uses engine coolant (hot water). The cooler also functions as an auxiliary heater that uses heated gas to heat the passenger compartment. The cooler includes an external refrigerant circuit and a compressor, which is driven by a vehicle engine. The external refrigerant circuit connects a discharge chamber (discharge pressure zone) with a suction chamber (suction pressure zone), which are defined in the compressor. The external refrigerant circuit includes a condenser, an expansion valve and an evaporator, which are arranged sequentially from the discharge pressure zone to the suction pressure zone. The discharge pressure zone of the compressor is also connected with the evaporator by a bypass, which bypasses the condenser and the expansion valve. A decompression device is located in the bypass. The passage between the discharge pressure zone and the suction pressure zone is switched by a switch valve. Specifically, the switch valve switches between a route including the condenser and the expansion valve and a route including the bypass, which bypasses the condenser and the expansion valve.
When the engine is started, the temperature of the coolant is low. Therefore, the main heater is unable to supply warm air to the passenger compartment. When the temperature of the coolant is low, the cooler is controlled to function as an auxiliary heater. Specifically, the switch valve selects the route that bypasses the condenser and the expansion valve. Then, high pressure, high temperature refrigerant gas discharged from the compressor is provided to the evaporator via the bypass and the decompression device. The heat of the gas is transferred by the evaporator. The heat of the refrigerant gas is added to the heat produced by the main heater, which allows the air conditioning system to quickly send warm air to the passenger compartment.
A typical prior art air conditioning system includes a variable displacement compressor
60
illustrated in
FIG. 6. A
suction chamber
61
, a discharge chamber
62
and a crank chamber
63
are defined in the compressor
60
. Cylinder bores
64
are formed in a cylinder block
65
. Each cylinder bore
64
houses a piston
66
. A drive shaft
67
is rotatably supported by the compressor housing. The drive shaft
67
is driven by a vehicle engine
68
. A swash plate
69
is supported by the drive shaft
67
in the crank chamber
63
to be tiltable relative to the drive shaft
67
. The pistons
66
are engaged with the swash plate
69
. A supply passage
70
communicates the discharge chamber
62
with the crank chamber
63
. A bleeding passage
71
communicates the crank chamber
63
with the suction chamber
61
. A control valve
72
is located in the supply passage
70
.
Rotation of the drive shaft
67
is converted to linear reciprocation of each piston
66
by the swash plate
69
. Reciprocation of each piston
66
draws refrigerant gas from the suction chamber
61
to the associated cylinder bore
64
. The gas is then compressed and discharged to the discharge chamber
62
. The control valve
72
adjusts the flow rate of gas in the supply passage
70
thereby varying the pressure of the crank chamber
63
. This changes the difference between the pressure of the crank chamber
63
and the pressure of the cylinder bores
64
. Accordingly, the inclination of the swash plate
69
is changed.
When the control valve
72
opens the supply passage
70
, highly pressurized gas in the discharge chamber
62
is supplied to the crank chamber
63
, which increases the pressure of the crank chamber
63
. The difference between the pressure of the crank chamber
63
and the pressure in the cylinder bores
64
decreases the inclination of the swash plate
69
. This shortens the stroke of each piston and decreases the displacement of the compressor
60
.
When the control valve
72
closes the supply passage
70
, highly pressurized gas in the discharge chamber
62
is not supplied to the crank chamber
63
. Since the crank chamber
63
is connected to the suction chamber
61
, the pressure of which is relatively low, by the bleeding passage
71
, the pressure of the crank chamber
63
is lowered. Then, the pressure of the cylinder bores
64
moves the swash plate
69
to increase the inclination of the swash plate
69
. This lengthens the stroke of each piston
66
and increases the displacement of the compressor
60
.
The compressor
60
has a spring
73
to urge the swash plate
69
in a direction decreasing the inclination. When the compressor
60
is stopped, the spring
73
moves the swash plate
69
to minimize the inclination. When the compressor
60
is started again, the displacement of the compressor
60
is minimum, which requires minimum torque. The shock caused by starting the compressor is thus reduced. If the nonoperational state of the compressor continues, the pressures in the chambers of the compressor
60
become equalized at a relatively low pressure. Therefore, when the compressor
60
is started again, it takes a relatively long time to maximize the cooling performance or the heating performance in the auxiliary heater. That is, the pressure in the discharge chamber
62
is increased slowly and it takes a relatively long time for the swash plate
69
to move from the minimum displacement position to the maximum displacement position. The compressor in the prior art air conditioning system is therefore slow to start functioning to cool the passenger compartment and slow to work as an auxiliary heater. When the temperature about the evaporator is low, the evaporator transfers a significant amount of heat from the gas. In other words, the work of the evaporator is increased. Therefore, the evaporator greatly lowers the pressure of the gas. In this case, it takes even longer time to increase the pressure of the discharge chamber
62
. That is, it takes a relatively long time for the compressor
60
to start functioning as the auxiliary heater.
SUMMARY OF THE INVENTION
Accordingly, it is an objective of the present invention to provide an air conditioning system that is quick to start functioning as a cooler or a heater when started.
To achieve the foregoing and other objectives and in accordance with the purpose of the present invention, an air conditioning system for cooling or heating a space is provided. The system includes a compressor, a port, heat exchanger, a cooling circuit, a heating circuit, a selecting valve apparatus and a control valve. The compressor has a system for drawing in refrigerant gas, compressing the gas, and discharging the gas after compression. The commpressed gas is supplied to an external circuit via the port. The external circuit includes the cooling circuit and the heating circuit. The heat exchanger cools or heats air supplied to the space. The cooling circuit includes a condenser that condenses the compressed refrigerant gas and supplies the condensed refrigerant gas to the heat exchanger. The heating circuit optionally supplies the compressed refrigerant gas to the heat exchanger. The selecting valve apparatus selectively connects the cooling circuit or the heating circuit to the heat exchanger. The control valve controls the cross-sectional area of the port to lower the discharge amount of the refrigerant gas discharged from the compressor.
Other aspects and advantages of the invention will become apparent from the following description, taken in conjunction with the accompanying drawings, illustrating by way of example the principles of the invention.
REFERENCES:
patent: 4330999 (1982-05-01), Nakayama
patent: 4687419 (1987-08-01), Suzuki et al.
patent: 4780059 (1988-10-01), Taguchi
patent: 4880356 (1989-11-
Fujii Toshiro
Okabe Takanori
Yokomachi Naoya
Kabushiki Kaisha Toyoda Jidoshokki Seisakusho
McDermott Corrine
Morgan & Finnegan L.L.P.
Norman Marc
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