Pumps – Three or more cylinders arranged in parallel – radial – or...
Reexamination Certificate
1999-04-12
2001-08-28
Thorpe, Timothy S. (Department: 3746)
Pumps
Three or more cylinders arranged in parallel, radial, or...
C417S238000, C417S222200, C092S059000
Reexamination Certificate
active
06280152
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a fixed capacity swash plate type compressor that has a fixed refrigerant discharge capacity, and a manufacturing method for the same.
2. Description of the Related Art
There are two types of conventional swash plate type compressors used with automotive air conditioners. In one type, the tilt angle or inclination of the swash plate with respect to a drive shaft is fixed so as to fix the discharge capacity of a refrigerant. The other is a variable capacity type in which the inclination of the swash plate with respect to the drive shaft is changed to so that the discharge capacity of the refrigerant may be changed.
The foregoing conventional fixed capacity swash plate type compressor has a simpler structure than the variable capacity swash plate type compressor, thus having the advantage of a lower cost. The fixed capacity type, however, has a problem in that it has great pressure fluctuations at startup i.e., a large startup shock because the pistons therein always operate at full stroke. The fixed capacity type also has a problem in that frequent switching ON/OFF of an electromagnetic clutch causes shock because the refrigerating capacity is adjusted by turning the electromagnetic clutch ON/OFF.
On the other hand, variable capacity swash plate type compressors are operated with the swash plate thereof set at a minimum inclination at startup, so that startup shocks such as those taking place in the fixed capacity swash plate type compressor are suppressed. Further, the variable capacity type does not require that the electromagnetic clutch be turned ON/OFF frequently because the inclination of the swash plate is adjusted in accordance with refrigeration load to control the capacity; therefore, it provides higher operating efficiency and is superior in terms of comfort. The variable capacity type, however, incorporates a hinge mechanism for changing the inclination of the swash plate according to crank chamber pressure and is constructed so as to control the crank chamber pressure arising from changes in a suction pressure with a capacity control valve assembly installed in the housing assembly. This has a drawback in that the structure becomes more complicated with more components and the use of the expensive capacity control valve assembly leads to higher cost.
Thus, both types of swash plate compressors have their advantages and disadvantages, so that they need to be chosen properly according to individual applications. However, there are a considerable number of components that have not been standardized even for compressors having the same capacity because of the structural difference in which the inclination of the swash plate is either fixed or made variable. This has been adversely affecting efforts for achieving economies of mass production and has been responsible for increased cost.
As a solution to the problem discussed above, there has been disclosed, in Japanese Patent Application Laid-open No. 9-228948, a fixed capacity swash plate type compressor intended for standardized components. This conventional known fixed capacity swash plate type compressor is fabricated by replacing a rear housing provided with a capacity control valve assembly in a variable capacity swash plate type compressor with a rear housing that is not provided with the capacity control valve assembly. Hence, the standardization of components between these two compressors is not yet very satisfactory. In addition, the structural modification requires that the assembly procedure or assembly process of the variable capacity swash plate type compressor be significantly changed. Thus, further improvements in productivity has been demanded.
SUMMARY OF THE INVENTION
Accordingly, the present invention has been made with a view toward solving the problems described above, and it is an object thereof to provide a fixed capacity swash plate type compressor adapted to use the same components and assembly process as those of a variable capacity swash plate type compressor to thereby lower the cost thereof.
To this end, according to one aspect of the present invention, in a variable capacity swash plate type compressor, a capacity control valve assembly, which controls the opening of at least either the communication between a crank chamber area and a discharge pressure area or the communication between a crank chamber area and a suction pressure area to adjust a crank chamber pressure, is replaced by a cock member that maintains continuous communication between a crank chamber area and a suction pressure area, to disable capacity control while the compressor is in operation, the cock member being placed in a housing of the capacity control valve assembly.
According to the present invention configured as described above, a variable capacity swash plate type compressor can be modified into a fixed capacity swash plate type compressor simply by replacing the capacity control valve assembly having a complicated structure with the cock member, while leaving the rest of the structure of the compressor unchanged. Hence, inexpensive components can be used, and commonality of the components and manufacturing processes can be achieved to improve productivity, thus permitting a further reduction in cost.
In addition, the swash plate is adapted to allow a change of the inclination similar to that of the variable capacity swash plate type compressor. Therefore, when the compressor that has been in a balanced state in pressure during a halt is started up, the swash plate is at a minimum inclination; hence, startup shock will be suppressed, contributing to extended service life of internal components.
In a preferred form of the present invention, in a case wherein the capacity control valve assembly in the variable capacity swash plate type compressor controls the opening and closing of the communication between the crank chamber area and the suction pressure area, the capacity control valve assembly is replaced by a cock member that is adapted to maintain the communication between the crank chamber area and the suction pressure area continuously. The cock member is arranged in a bleed passage between the crank chamber and the suction pressure area and is adapted to maintain the continuous communication between the crank chamber area and the suction pressure area in the compartment.
In another preferred form of the present invention, in a case wherein the capacity control valve assembly in the variable capacity swash plate type compressor controls the opening and closing of the communication between the discharge pressure area and the crank chamber area, the capacity control valve assembly is replaced by a cock member that is adapted to always cut off the communication between the discharge pressure area and the crank chamber area at all times, the cock member being placed in the housing.
In yet another preferred form of the present invention, in the immediately preceding preferred form, the cock member is provided with a passage allowing communication between the discharge pressure area and an atmospheric pressure area, and a relief valve mechanism is installed in the passage for releasing refrigerant gas in the discharge pressure area to the atmosphere if a discharge pressure exceeds a predetermined value.
With this arrangement, since the relief valve mechanism is provided in the cock member, there is no need to employ a relief valve separately. Hence, it is possible to further reduce the cost.
In a further preferred form in accordance with the present invention, in a case wherein the capacity control valve assembly in the variable capacity swash plate type compressor controls the opening and closing of the communication between the discharge pressure area and the crank chamber area and the communication between the crank chamber area and the suction pressure area, respectively, the capacity control valve assembly is replaced by a cock member that is adapted to always cut off the communication between the discharge area and the crank
Hoshida Takahiro
Sugiura Manabu
Kabushiki Kaisha Toyoda Jidoshokki Seisakusho
Morgan & Finnegan L.L.P.
Thorpe Timothy S.
Tyler Cheryl J.
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