Refrigeration – Automatic control – Refrigeration producer
Reexamination Certificate
1999-04-13
2001-07-17
Tanner, Harry B. (Department: 3744)
Refrigeration
Automatic control
Refrigeration producer
C062S228300
Reexamination Certificate
active
06260369
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates generally to a flow control valve adapted for being incorporated in a variable displacement refrigerant compressor. More particularly, the present invention relates to a variable displacement refrigerant compressor accommodating therein a flow control valve which permits the compressor to be incorporated in a refrigerating system for a vehicle climate control system.
2. Description of the Related Art
A climate control system for a vehicle incorporates a compressor to compress a refrigerant gas. One typical refrigerant compressor for use in a vehicle climate control system is a conventional variable displacement refrigerant compressor, which is provided with a drive shaft driven for a variable rotation about an axis of rotation thereof by an external drive source, pistons slidably fitted in cylinder bores formed in a cylinder block so as to be reciprocated to suck a refrigerant gas from a suction chamber, to compress the sucked refrigerant gas in the cylinder bores, and to discharge the compressed refrigerant gas from the cylinder bores into a discharge chamber, a variable-inclination cam plate mounted to rotate with the drive shaft within a crank chamber and to be operatively engaged with the pistons to cause the reciprocation of the pistons in response to the rotation thereof while reducing the stroke of reciprocating movement of the pistons in response to an increase in a pressure prevailing in the crank chamber, a controlling passage extending between the discharge chamber and the crank chamber to control the pressure in the crank chamber, and a flow control valve arranged in the controlling passage to control the size of an opening in a portion of the controlling passage.
In the above-described variable displacement refrigerant compressor, when a fluorinated hydrocarbons gas is used as the refrigerant gas, and when the refrigerant compressor is incorporated in a refrigerating system operated under a condition such that a discharge pressure and a suction pressure of the refrigerant gas are always kept below a critical pressure of the refrigerant gas (this type of refrigerating system will be hereinafter referred to as a subcritical-cycle-type refrigerating system), it is possible to adjustably change the displacement of the variable displacement refrigerant compressor by the use of the flow controlling valve as schematically shown in FIG.
14
.
Referring to
FIG. 14
, the conventional flow control valve is constructed so as to be arranged in the controlling passage which extends between the discharge chamber and the crank chamber. The flow control valve is provided with a pressure sensing member
80
moving in response to a detection of a change in a suction pressure Ps, and a valve element
81
connected to the pressure sensing member
80
and movable to adjustably open and close a port
83
a
of the controlling passage
83
in response to the movement of the pressure sensing member
80
. The flow control valve receives the suction pressure Ps at the pressure sensing member
80
and moves the valve element
81
in a direction closing the port
83
a
of the controlling passage in response to an increase in the suction pressure Ps. Further, the pressure sensing member
80
of the flow control valve constantly receives a pressing force F of a spring
82
(this pressing force F of the spring is determined by design) to urge the valve element
81
, via the pressure sensing member
80
, in a direction opening the port
83
a
of the controlling passage
83
. The valve element
81
is arranged so as to constantly receive a discharge pressure Pd by which the valve element
81
is urged in a direction to open the portion
83
of the controlling passage.
Thus, the above-mentioned flow control valve acts so that the valve element
81
opens the port
83
a
of the controlling passage
83
when the suction pressure Ps reduces to a pressure below a predetermined set pressure value (it is referred to as a set suction pressure), in order that the refrigerant gas under a discharge pressure Pd flows from the discharge chamber into the crank chamber through the opened port
83
a
of the controlling passage
83
. As a result, when a pressure Pc in the crank chamber is increased, the cam plate is moved toward a position which reduces the angle of inclination thereof, so that the stroke of reciprocating movement of the pistons is reduced. As a result, the displacement of the compressor is reduced.
In accordance with the above-described arrangement of the flow control valve, the valve element
81
of the flow control valve constantly receives the discharge pressure Pd urging the valve element
81
in a direction to close the port
83
a
of the controlling passage
83
. Therefore, when the spring
82
is set so as to exert a predetermined constant force F, the flow control valve indicates such a control characteristics that the set value of the suction pressure Ps acting on the pressure sensing member
80
may be reduced as the discharge pressure Pd acting on the valve element
81
increases. Namely, the relationship between the discharge pressure Pd and the suction pressure Ps which act in the flow control valve indicates a characteristic curve represented by a straight line sloping down from the left to the right in a rectangular coordinates, as shown in FIG.
15
. Thus, when the discharge pressure Pd acting on the valve element
81
increases, the set value of the suction pressure Ps acting on the pressure sensing member
80
decreases.
When an actual pressure level of the suction pressure Ps prevailing in the suction pressure region in the refrigerant compressor reduces to a value in an area below the line in
FIG. 15
, the valve element
81
of the flow control valve is moved to a position opening the port
83
a
permitting the refrigerant gas under the discharge pressure Pd to enter the crank chamber, and accordingly, when the pressure Pc in the crank chamber is increased, the cam plate is moved to reduce the displacement of the compressor.
Nevertheless, when a refrigerant compressor incorporating therein the above-described flow control valve is operated under a high rotating speed, and when an amount of the refrigerant circulating through a refrigerating system is increased until an excessive increase in the refrigerating performance of the refrigerating system occurs, it is very difficult to quickly reduce the refrigerating performance of the refrigerating system by adjustably controlling the displacement of the refrigerant compressor. This difficulty in controlling the displacement of the compressor is specifically encountered by a refrigerating system of the type in which a closed refrigerant-circulation path of the refrigerating system includes a high-pressure path in which the refrigerant is under a high discharge pressure and, more specifically, is under a supercritical pressure. This type of refrigerating system will be hereinafter referred to as a supercritical-cycle-refrigerating system and, in this system, when the rotating speed of the refrigerant compressor accommodated in the system is increased, the pressure (the discharge pressure) in the high-pressure path can be quickly increased. However, in a low-pressure path of the refrigerant-circulating path, an evaporating pressure (a suction pressure) of the refrigerant cannot be quickly reduced. Thus, when the flow control valve incorporated in the refrigerant compressor has the aforementioned operating characteristics having a straight line relationship between Pd and Ps, and when the rotating speed of the compressor is increased to increase the discharge pressure Pd, the set pressure value of the suction pressure Ps acting on the pressure sensing member
80
of the flow control valve is accordingly reduced to make it difficult to quickly move the valve element
81
in a direction opening the port
83
a
of the controlling passage
83
. Namely, the control of the displacement of the refrigerant compressor is delayed.
EP-0604417B1, based on PCT/N0
Fujii Toshiro
Koide Tatsuya
Murakami Kazuo
Yokomachi Naoya
Kabushiki Kaisha Toyoda Jidoshokki Seisakusho
Tanner Harry B.
Woodcock Washburn Kurtz Mackiewicz & Norris LLP
LandOfFree
Flow control valve for a variable displacement refrigerant... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Flow control valve for a variable displacement refrigerant..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Flow control valve for a variable displacement refrigerant... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2494670