Pumps – Condition responsive control of drive transmission or pump... – Adjustable cam or linkage
Reexamination Certificate
2001-12-04
2003-07-01
Freay, Charles G. (Department: 3746)
Pumps
Condition responsive control of drive transmission or pump...
Adjustable cam or linkage
C062S114000, C062S498000, C251S129040
Reexamination Certificate
active
06585494
ABSTRACT:
TECHNICAL FIELD
The present invention relates to a variable-capacity control apparatus to be employed in conjunction with a refrigerating cycle which uses carbon dioxide as the coolant and includes a variable-capacity compressor provided with a swash plate tiltably secured to a drive shaft and a piston caused to move reciprocally inside a compression space as the drive swash plate rotates to vary the capacity for the coolant flowing through the refrigerating cycle by varying the piston stroke in correspondence to the tilt angle of the drive swash plate based upon the difference between the pressure in the compression space and the piston back pressure.
BACKGROUND ART
The pressure control valve used in the variable-capacity swash plate compressor disclosed in Japanese Unexamined Patent Publication No. H 5-99136 includes a first control valve that implements open/close control on the communication between an outlet chamber and a crank case, a second control valve that implements open/close control on the communication between the crank case and an intake chamber, a transmission rod that engages the first and second control valve in operation, an electromagnetic actuator that moves the transmission rod and the pressure-sensitive member (such as a diaphragm or a bellows) that engages the second control valve in operation by sensing the pressure within the intake chamber.
The control valve for a variable-capacity compressor disclosed in Japanese Unexamined Patent Publication No. H 9-268974 comprises a valve element that opens/closes an air supply passage communicating between an outlet pressure area and a crank case, a pressure-sensitive unit that is linked to one side of the valve element via a pressure-sensitive rod to achieve interlocked operation and is housed within a pressure-sensitive chamber communicating with an intake pressure area to apply a force to the valve element along the direction in which the degree of openness of the air supply passage is reduced as the pressure in the intake pressure area rises, a solenoid unit that is linked to the other side of the valve element via a solenoid rod to achieve interlocked operation and applies a load to valve element along the direction in which the degree of openness of the air supply passage is reduced as the solenoid becomes excited and a means for forced opening that applies a force to the valve element along the direction in which the air supply passage is forcibly opened as the solenoid becomes demagnetized, with the valve element and the pressure-sensitive unit linked with each other in such a manner that the contact between the valve element and the pressure-sensitive unit can be established/cut off freely.
When the pressure within the pressure-sensitive chamber enters a high intake pressure condition while the solenoid at the solenoid unit remains demagnetized, the pressure-sensitive unit becomes displaced along the direction in which the degree of openness of the air supply passage is reduced. At this time, the force applied by the means for forced opening to the valve element works in the opposite direction from the direction of the displacement of the pressure-sensitive unit, thereby causing the pressure-sensitive unit and the valve element to separate from each other and sustaining the valve element at its maximum opening position. It is to be noted that the publication above discloses that the pressure-sensitive unit is constituted of a bellows and also discloses that it may alternatively be constituted of a diaphragm.
However, when utilizing a control valve having a diaphragm or a bellows to constitute the pressure-sensitive element at the pressure-sensitive unit as in the examples referred to above in conjunction with a refrigerating cycle that uses carbon dioxide as the coolant with the pressure inside the refrigerating cycle reaching a level as high as approximately 10 times that in a refrigerating cycle using freon as the coolant as in the prior art, a problem arises in that it is difficult to achieve a satisfactory degree of pressure withstanding performance at the pressure-sensitive element. There is another problem in that since it is necessary to apply the electromagnetic force of the electromagnetic actuator provided to drive the valve against a high pressure, the size of the electromagnetic actuator itself is bound to be large.
Accordingly, an object of the present invention is to provide a variable capacity control apparatus for a refrigerating cycle that implements reliable variable-capacity control while achieving a satisfactory level of coolant pressure withstanding performance against the pressure in the refrigerating cycle using carbon dioxide as the coolant without having to increase the size of the pressure control valve.
DISCLOSURE OF THE INVENTION
In order to achieve the object described above, a refrigerating cycle that uses carbon dioxide as a coolant, comprising at least a variable-capacity compressor having at least a cylinder block, a drive shaft provided inside the cylinder block, a drive swash plate that rotates together with the drive shaft and whose angle of inclination relative to the drive shaft can be varied freely, a plurality of cylinders provided within the cylinder block, each having an axis parallel to the drive shaft, a plurality of pistons slidably provided at the cylinders and caused to make reciprocal movement within the cylinders as the drive swash plate rotates, compression spaces defined by the cylinders and the pistons, a crank case formed on a non-compression side of the pistons, an intake chamber that communicates with the compression spaces during the intake phase of the pistons and an outlet chamber that communicates with the compression spaces during the compression phase of the pistons, a radiator that cools the coolant having been compressed at the variable-capacity compressor, a means for expansion that expands the coolant having been cooled by the radiator and an evaporator that evaporates the coolant having been expanded by the means for expansion, is further provided with a variable-capacity mechanism that includes at least a low pressure chamber that communicates with the intake chamber, a high pressure chamber that communicates with the outlet chamber, a pressure adjustment chamber that communicates with the crank case, a low pressure side communicating port provided between the pressure adjustment chamber and the low pressure chamber, a high pressure side communicating port provided between the pressure adjustment chamber and the high pressure chamber, a valve element that opens/closes the low pressure side communicating port and, at the same time, opens/closes the high pressure side communicating port, an electromagnetic coil that generates an electromagnetic force, a plunger that is slidably inserted at the electromagnetic coil and is moved by the electromagnetic force imparted by the electromagnetic coil to cause the valve element to move and a spring that applies a force to the valve element along the direction opposite from the direction in which the valve element is caused to move by the plunger, a pressure sensor that detects the pressure on a low pressure line extending from the outlet side of the means for expansion to the intake side of the variable-capacity compressor in the refrigerating cycle and a means for control that controls the electromagnetic coil to move the valve element along the direction in which the pressure adjustment chamber and the low pressure chamber come into communication with each other and the pressure adjustment chamber becomes cut off from the high pressure chamber if the low level pressure detected by the pressure sensor is higher than a target pressure and to move the valve element along the direction in which the pressure adjustment chamber becomes cut off from the low pressure chamber and the pressure adjustment chamber and the high pressure chamber come into communication with each other if the low level pressure is lower than the target pressure are provided.
According to the present invention provided with the
Belena J F
Freay Charles G.
Wenderoth , Lind & Ponack, L.L.P.
Zexel Valeo Climate Control Corporation
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