Air conditioning systems

Details Air conditioning systems Air conditioning systems

1999-10-04

2001-06-26

Tanner, Harry B. (Department: 3744)

Refrigeration

Automatic control

Refrigeration producer

C062S228500

Reexamination Certificate

active

06250094

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Technical Field
The present invention relates to air conditioning systems that utilize refrigerants and a compressor, and particularly to air conditioning systems capable of alleviating excessive increases in refrigerant discharge pressure within a heating circuit.
2. Description of the Related Art
A known air conditioning system is disclosed in Japanese Patent Application No. 7-19630 and includes a compressor
1
, a cooling circuit
51
, a heating circuit
52
and a controller
83
, as shown in FIG.
1
. The cooling circuit
51
includes a condenser
55
, a first expansion valve
57
and a heat exchanger
59
provided on a passage connecting a discharge port D to a suction port S of the compressor
1
. High pressure refrigerant discharged from the discharge port D of the compressor
1
is drawn through the above respective devices and back to the compressor
1
.
The heating circuit
52
includes a bypass passage
52
a
extending from the discharge port D of the compressor
1
to the heat exchanger
59
. A second expansion valve
63
provided within the bypass passage
52
a
between the discharge port D and the heat exchanger
59
. The high pressure refrigerant discharged from the compressor
1
is not directed to the condenser
55
, but rather is drawn by the compressor
1
through the second expansion valve
63
and the heat exchanger
59
. Such a heating circuit
52
is generally known as a hot gas bypass heater.
The operation of the cooling circuit
51
and the heating circuit
52
is changeably selected by opening and closing selector valves
53
a
and
53
b
, which opening and closing operations are performed by the controller
83
.
Because the refrigerant discharge pressure is higher when the heating circuit
52
is used than when the cooling circuit
51
is used, the air conditioning system must operate in a high pressure state when the heating circuit
52
is utilized. An abnormally high-pressure state may be created if the output discharge capacity of the compressor
1
temporarily increases during the operation of the heating circuit
52
. A refrigerant releasing passage
91
having a pressure relief valve
93
is provided in order to release excess pressure from the heating circuit
52
, if an abnormally high pressure state is reached. The refrigerant releasing passage
91
is connected to the heating circuit
52
and the cooling circuit
51
and the pressure relief valve
93
can be opened to release the refrigerant from the heating circuit
52
into the cooling circuit
51
when the refrigerant discharge pressure abnormally increases during the operation of the heating circuit
52
.
Because the cooling circuit
51
and the heating circuit
52
are alternatively selected by the selector valves
53
a
and
53
b
, the refrigerant is released into the cooling circuit
51
which is not used in operation of the heating circuit
52
, thereby preventing the discharge pressure at the heating circuit
52
from increasing abnormally.
However, because the refrigerant in the heating circuit
52
is released into the cooling circuit
51
whenever the discharge pressure abnormally increases, the amount of refrigerant in the heating circuit
52
is reduced and heating performance may be reduced. Moreover, because the high pressure refrigerant is wastefully released from the heating circuit, energy efficiency is reduced.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide an air conditioning system that can alleviate abnormally high pressure states more efficiently.
Preferably, an air conditioning system may include a compressor having a driving chamber, a heating circuit and a controller. This system may release abnormally high pressure refrigerant from the compressor discharge port into the compressor driving chamber in accordance with differences between the refrigerant discharge pressure discharged from the compressor and refrigerant suction pressure at the compressor suction port or the refrigerant pressure within the driving chamber. By increasing the pressure within the driving chamber, the compressor discharge capacity can be reduced. As a result, the discharge pressure of the compressor will be reduced by the reduction in the compressor discharge capacity. Because the abnormally high pressure refrigerant is conserved within the compressor by such operation, refrigerant is not wastefully released into a cooling system. Furthermore, because the abnormally high pressure refrigerant is actually utilized to decrease the system pressure to normal operating pressure levels, the heating performance and efficiency of the system can be improved over known air conditioning systems.
The controller may be influenced by pressure differences within the compressor to thereby simplify the airtight structure of a valve that permits the refrigerant to be released into the compressor driving chamber.
Other objects, features and advantages of the present invention will be readily understood after reading the following detailed description together with the accompanying drawings and the claims.


REFERENCES:
patent: 4687419 (1987-08-01), Suzuki et al.
patent: 4709555 (1987-12-01), Kawai et al.
patent: 4780059 (1988-10-01), Taguchi
patent: 5201189 (1993-04-01), Yokomachi et al.
patent: 5823000 (1998-10-01), Takai
patent: 5-223357 (1993-08-01), None
patent: 7-19630 (1995-01-01), None
patent: 10-47242 (1998-02-01), None

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