Refrigeration – Automatic control – Refrigeration producer
Reexamination Certificate
1999-04-13
2001-02-27
McDermott, Corrine (Department: 3744)
Refrigeration
Automatic control
Refrigeration producer
C417S222200
Reexamination Certificate
active
06192699
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a variable capacity compressor. The present invention is applicable to refrigerant compressors, in particular, variable capacity compressors having single-head-type pistons.
2. Description of Related Art
There has been a variable capacity compressor which is a wobble type or a swash type and which is mainly employed for vehicle air-conditioners. The variable capacity compressor has a cam plate which is connected with a rotor by way of a hinge mechanism and which is to be oscillated around a fulcrum. The compressor varies a pressure of a crankcase chamber having the cam plate, controlling a force working to the rear surface of the single-head-type piston, and balancing the rear surface and the front surface of the single-head-type piston. Accordingly, the compressor varies an inclination angle of the cam plate around the fulcrum of the cam plate. Namely, the compressor varies a piston-stroke.
The compressor sucks a refrigerant gas, which returns from an exterior refrigerating circuit, from a suction chamber, supplying the sucked refrigerant gas into bores by reciprocating the pistons, compressing the refrigerant gas, and thereby discharging the refrigerant gas into a discharge chamber. As aforedescribed, the compressor has a construction in which the refrigerant gas doesn't pass through the crankcase chamber but directly flows into the bores fitting the corresponding pistons. Accordingly, lubricating ability with respect to sliding parts disposed in the crankcase chamber depends on a blow-by gas leaked to the crankcase chamber. Also, lubricating ability with respect to the sliding parts in the crankcase chamber depends on lubricating oil contained in the refrigerant gas in discharge pressure which is positively supplied into the crankcase chamber during capacity-control to change the pressure in the crankcase chamber.
The conventional compressor is provided with a shaft sealing member arranged for sealing an exposed end portion of the drive shaft. Since the shaft sealing member is arranged in a shaft hole, located apart from the crankcase chamber, the refrigerant gas flowing toward the shaft sealing member is extremely decreased in quantity. As a result, the compressor causes secondary anxiety that the shaft sealing member is heat-deteriorated by shortage of the lubricating and the cooling, and that a clutch slips by gas-leakage.
Japanese Unexamined Patent Publication No. 7-332,250 discloses the compressor in which an appended passageway is disposed in the inside of a drive shaft along a shaft centre thereof. One end passageway portion of the appended passageway is opened in a shaft hole of a front housing, and another end passageway portion of the appended passageway is communicated with a suction pressure area. Also, this publication discloses a technique that the refrigerant gas in the crankcase chamber flows into the suction pressure area by way of the neighborhood of the shaft sealing member.
Judging from view that it is preferable that the shaft sealing member is fully lubricated and cooled, such construction concerning the publication is not satisfied. The reason is that the refrigerant gas—a flow stream from the crankcase chamber to the suction pressure area—is not limited only within the aforesaid appended passageway formed in the inside of the drive shaft. Namely, the refrigerant gas flows into the suction pressure area, not only by way of the aforesaid appended passageway but also by way of another passageway which passes through the radial bearing for supporting the drive shaft arranged in a central hole of a cylinder block.
In other words, since the refrigerant gas flows in two-passageways in the aforedescribed way, less lubricating oil is supplied to the shaft sealing member with the refrigerant gas, as a logical consequence. Also, a pressure reduction is not largely generated at a sealed portion sealed by the shaft sealing member; so, it is apparent that the conventional compressor concerning the aforesaid publication does not cool the shaft sealing member effectively.
SUMMARY OF THE INVENTION
The present invention has been developed in view of the aforementioned circumstances. It is therefore an object of the present invention to provide a variable capacity compressor which improves endurance of a shaft sealing member by designating a transpire passageway connected with a crankcase chamber and a suction pressure area.
In the first aspect of the present invention, a variable capacity compressor comprises: (1) a cylinder block including a plurality of bores arranged therein, constituting a body of the compressor, and having a front end and a rear end; (2) a front housing including a shaft hole, and a crankcase chamber disposed in the inside thereof, the front housing closing the front end of the cylinder block, and the crankcase chamber having a rotor and a hinge mechanism; (3) a drive shaft rotatably supported by the cylinder block and the front housing, the drive shaft having an end portion disposed in the shaft hole of the front housing; (4) a shaft sealing member disposed in the shaft hole between the drive shaft and the front housing for sealing the shaft hole of the front housing; (5) a rear housing including a suction pressure area and a discharge pressure area, and the rear housing closing the rear end of the cylinder block; (6) a cam plate connected to be inclined with respect to the drive shaft, and connected with the rotor by way of the hinge mechanism to synchronously be rotated with the drive shaft; (7) a plurality of pistons associated with the cam plate for reciprocating in each of the bores; (8) a capacity control valve for controlling a pressure of the crankcase chamber by supplying a discharge pressure from the discharge pressure area to the crankcase chamber, the capacity control valve for varying an inclination angle and a piston stroke on the basis of a differential pressure between a suction pressure and the pressure of the crankcase chamber; and (9) the improvement comprising;
(9-1) a transpire passageway exclusively communicated with a suction pressure area, having one end passageway portion being opened at a sealed portion being sealed by the shaft sealing member disposed in the shaft hole, and having another end passageway portion being opened the suction pressure area; and
(9-2) a throttle constituted by a clearance gap between an inner peripheral surface of an end portion of the shaft hole adjoining the crankcase chamber and an outer peripheral surface of the drive shaft.
In the first aspect of the present invention, the sealed portion sealed by the shaft sealing member is communicated with the crankcase chamber by way of the shaft hole of the front housing. Also, the sealed portion sealed by the shaft sealing member is communicated with the suction pressure area, which indicates a lower pressure, by the transpire passageway. Accordingly, an exclusive flow stream is generated in the refrigerant gas of the crankcase chamber, the exclusive flow stream moves toward the transpire passageway by way of the shaft sealing member because of a pressure difference. Therefore, the shaft sealing member is effectively lubricated and cooled by the flow stream.
In the case of a compressor which controls a capacity by controlling a pressure of the crankcase chamber, namely, by increasing a pressure of the crankcase chamber, the refrigerant gas is positively supplied to the crankcase chamber, and accordingly, the shaft sealing member is more effectively lubricated and cooled. Also, the throttle, communicated with the transpire passageway, is constituted by a clearance gap between an inner peripheral surface of an end portion of the shaft hole adjoining the crankcase chamber and an outer peripheral surface of the drive shaft. Therefore, the throttle decreases a back pressure of the shaft sealing member to the same pressure as the suction pressure area, thereby remarkably decreasing load applied to the shaft sealing member, and thereby obtaining a cooling ability c
Kato Keiichi
Kurakake Hirotaka
Kurita Hajime
Ota Masaki
Drake Malik N.
Kabushiki Kaisha Toyoda Jidoshokki Seisakusho
McDermott Corrine
Morgan & Finnegan L.L.P.
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