Refrigeration – Automatic control – Refrigeration producer
Reexamination Certificate
2002-01-23
2003-07-22
Wayner, William (Department: 3744)
Refrigeration
Automatic control
Refrigeration producer
C417S222200
Reexamination Certificate
active
06595015
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 effectively 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 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
that extends from the discharge port D of the compressor
1
to the heat exchanger
59
. A second expansion valve
63
is 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
and this cycle is repeated. 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 air conditioning system is used in a state in which the refrigerant discharge pressure is higher when the heating circuit
52
is used than when the cooling circuit
51
is used, abnormally high pressure is likely to be applied during operation of the heating circuit
52
. For example, the abnormally high-pressure state is likely to occur when a rotation speed of the compressor
1
is increased temporarily during operation of the heating circuit
52
. Therefore, the air conditioning system is further provided with a refrigerant releasing passage
91
having a pressure relief valve
93
. 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
to 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 toward the cooling circuit
51
which is not used when the discharge pressure is increased abnormally during operation of the heating circuit
52
, thereby preventing the discharge pressure at the heating circuit
52
from increasing abnormally.
Because the refrigerant is released from the operating heating circuit
52
to the cooling circuit
51
which is not used, the abnormally high-pressure state of the discharge pressure during operation of the heating circuit
52
can be alleviated. However, because the refrigerant in the heating circuit
52
is released into the cooling circuit
51
whenever the discharge pressure increases, the amount of the 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 by working the compressor
1
, energy efficiency is reduced.
SUMMARY OF THE INVENTION
It is, therefore, an object of the present invention to provide an air conditioning system that can effectively alleviate abnormally high pressure state.
Preferably, the air conditioning system may include a compressor, a heating circuit, and a capacity controller. The compressor has a suction port, a discharge port, a driving unit provided within a compressor driving chamber, a first passage and a second passage. The driving unit may decrease compressor output discharge capacity when the pressure within the driving chamber increases. The first passage may connect the discharge port to the driving chamber and the second passage may connect the driving chamber to the suction port. The capacity controller may open the first passage when the refrigerant discharge pressure reaches or exceeds a high set point pressure, that is, a predetermined pressure. By opening the first passage, the high-pressure refrigerant may be released from the discharge port to the driving chamber through the first passage. Thus, the pressure within the driving chamber may increase. By increasing the pressure within the driving chamber, the compressor output discharge capacity can be reduced. As the result, the discharge pressure of the compressor will be reduced by the reduction in the compressor output discharge capacity.
In particular, the air conditioning system can solve a problem of insufficient heating performance due to release of the refrigerant within the heating circuit into the cooling circuit for alleviating the abnormally high-pressure state of the discharge pressure during operation of the heating circuit. Moreover, the air conditioner can solve a problem of low energy efficiency due to wasteful release of the high-pressure refrigerant from the heating circuit to the outside.
As another example, the air conditioning system may preferably include a capacity controller that can close the second passage, when the refrigerant discharge pressure reaches or exceeds a high set point pressure, that is, a predetermined pressure. In this example, the high-pressure refrigerant may be released at all times from the discharge port to the driving chamber through the first passage. The refrigerant within the driving chamber may be released into the suction port through the second passage in a normal operation of the air conditioning system. By releasing the refrigerant from the driving chamber into the suction port, pressure within the driving chamber can not increase in a normal operation. To the contrary, the capacity controller can close the second passage when the discharge pressure reaches or exceeds a high set point pressure, that is, a predetermined pressure. By closing the second passage, refrigerant can not be released from the driving chamber into the suction port through the second passage. Thus, the pressure within the driving chamber may increase. By increasing the pressure within the driving chamber, the compressor discharge capacity can be reduced. As the result, the discharge pressure of the compressor can be reduced by the reduction in the compressor output discharge capacity.
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patent: 4723891 (1988-02-01), Takenaka et al.
patent: 4934157 (1990-06-01), Suzuki et al.
patent: 5022234 (1991-06-01), Goubeaux et al.
patent: 5282329 (1994-02-01), Teranishi
patent: 5291941 (1994-03-01), Enomoto et al.
patent: 6250094 (2001-06-01), Ban et al.
patent: 6293117 (2001-09-01), Ban et al.
patent: 6374625 (2002-04-01), Fujii et al.
patent: 0 894 651 (1999-02-01), None
patent: 0 980 976 (2000-02-01), None
patent: 04 043873 (1992-02-01), None
patent: 04 321779 (1992-11-01), None
patent: 06 200875 (1994-07-01), None
patent: 07 019630 (1995-01-01), None
patent: 08 021365 (1996-01-01), None
Fujii Toshiro
Koide Tatsuya
Okabe Takanori
Yokomachi Naoya
Kabushiki Kaisha Toyoda Jidoshokki Seisakusho
Wayner William
Woodcock & Washburn LLP
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