Air conditioning system

Details Air conditioning system Air conditioning system

1999-10-04

2001-09-25

Tanner, Harry B. (Department: 3744)

Refrigeration

Automatic control

Refrigeration producer

C062S228500

Reexamination Certificate

active

06293117

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an air conditioning system that utilize refrigerants and a compressor, and particularly to an air conditioning system that can prevent compressor driving chamber from reaching an abnormally high-pressure state.
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 a second expansion valve
63
provided within the bypass passage
52
a
and to 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 air conditioning system, 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 during 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.
Another variable displacement compressor is disclosed in Japanese Patent Application No. 10-47242. Although this compressor is not explicitly shown in the drawings, a connecting passage having a capacity control valve is provided between a discharge port and a driving chamber (also known as the crank case) in a housing such that refrigerant is released from the discharge port into the driving chamber when the capacity control valve is opened. Moreover, the driving chamber and a suction port communicate with each other such that the refrigerant in the driving chamber is sent to the suction port. When the discharge pressure is excessively high or suction pressure is excessively low in the compressor, the capacity control valve is opened to release the refrigerant from the discharge port into the driving chamber, thereby increasing the pressure in the driving chamber. As a result, the output discharge capacity of the compressor decreases and thus, the discharge pressure decreases and the suction pressure increases. In order to maintain the output discharge capacity decreasing effect by maintaining pressure in the driving chamber, a throttle can be provided between the driving chamber and the suction port.
If the variable displacement compressor disclosed in Japanese Patent Application No. 10-47242 is employed in an air conditioning system having the hot gas bypass heater circuit disclosed in Japanese Patent Application No. 7-19630, a problem can occur due to a combination of a characteristic of the variable displacement compressor and a characteristic of the hot gas bypass heater.
As described above, because the high-pressure refrigerant is released from the discharge port into the driving chamber in order to decrease the output discharge capacity, the pressure in the driving chamber increases significantly. Although the driving chamber and the suction port communicate with each other, it takes time to send the refrigerant from the driving chamber to the suction port and the pressure in the driving chamber is maintained in a high-pressure state during that time. Especially in the above case in which a throttle is provided between the driving chamber and the suction port, because a long time is required to send the refrigerant from the driving chamber to the suction port, the high-pressure state in the driving chamber continues for a long time.
Therefore, in the known variable displacement compressor, the driving chamber seal is designed based on the assumption that the interior of the driving chamber will be subjected to high-pressure states. Especially during operation of the heating circuit (hot gas bypais heater) which uses the refrigerant at higher pressure as compared with the cooling circuit, the pressure of the refrigerant released from the discharge port into the driving chamber may increase over an expected steady-state value in some cases and the interior of the driving chamber may reach an excessively high-pressure state in such cases. When the excessively high-pressure state is caused in this manner, airtight seal of the driving chamber is degraded and the durability of the compressor may be also degraded.
SUMMARY OF THE INVENTION
It is, therefore, an object of the present invention to provide an improved air conditioning system that can alleviate abnormal high pressure state more sufficiently.
Preferably, an air conditioning system includes an compressor having a driving chamber, a suction port, a discharge port, a first passage that connects the discharge port to the driving chamber by opening a capacity control valve, a second passage that connects the driving chamber to the suction port and a driving means that can change the output discharge capacity of the compressor by changing the pressure in the driving chamber. Further, the refrigerant may preferably be released from the driving chamber to the suction port separately from the second passage when the driving chamber reaches a predetermined high-pressure state.
In such an air conditioning system, abnormally high pressure problems are overcome. In particular, heating performance is improved, because high pressure refrigerant is not released from the hot gas bypass heater circuit into the cooling circuit. Further, an excessively high-pressure state in the driving chamber can be prevented.
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: 4905477 (1990-03-01), Takai
patent: 5189886 (1993-03-01), Terauchi
patent: 5694784 (1997-12-01), Frey et al.
patent: 5-223357 (1993-08-01), None
patent: 7-19630 (1995-01-01), None
patent: 10-47242 (1998-02-01),

Affiliated with

Also associated with

Rating

Air conditioning system does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Air conditioning system, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Air conditioning system will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-2463845