Piston installing method and positioning jig

Details Piston installing method and positioning jig Piston installing method and positioning jig

2000-06-13

2002-02-05

Ryznic, John E. (Department: 3745)

Expansible chamber devices

With assembly or disassembly facilitating means

C029S281500

Reexamination Certificate

active

06343540

ABSTRACT:

BACKGROUND OF THE INVENTION
The present invention relates to a method for installing pistons in a piston type compressor that compresses refrigerant gas in a vehicle air conditioner. Particularly, the present invention pertains to a method for installing pistons in cylinder bores and a positioning jig used for the method.
FIG. 8
illustrates a compressor. The compressor has a front housing member
101
and a cylinder block
102
. The front housing member
101
is secured to the front face of the cylinder block
102
to define a crank chamber
103
. A drive shaft
104
extends through the crank chamber
103
and is supported by the front housing member
101
and the cylinder block
102
. A swash plate
105
is coupled to the drive shaft
104
to rotate integrally with the drive shaft
104
.
Cylinder bores
106
are formed in the cylinder block
102
. Each cylinder bore
106
receives a single headed piston
107
. Each piston
107
is coupled to the swash plate
105
by shoes
108
. The compressor performs a compression cycle. In the compression cycle, rotation of the drive shaft
104
is converted to reciprocation of the pistons
107
by the swash plate
105
and the shoes
108
. Accordingly, refrigerant gas is drawn in to each cylinder bore
106
and is compressed in the cylinder bore
106
. Compressed refrigerant gas is then discharged from the cylinder bore
106
.
FIG. 9
illustrates a step in the assembly process of the compressor. Specifically,
FIG. 9
shows a step for installing the pistons
107
into the cylinder bores
106
. The pistons
107
are first coupled to the swash plate
105
to form a piston assembly Pa. A positioning jig
111
holds the pistons
107
at its circumferential position to align the axis L
2
of each piston
107
with the axis N
2
of the corresponding cylinder bore
106
.
In this state, the piston assembly Pa and the cylinder block
102
are brought closer to each other along the axes L
1
(or N
1
) of the piston assembly Pa and the cylinder block
102
such that each piston
107
is inserted into the corresponding cylinder bore
106
to a predetermined position. When the pistons
107
starts entering the cylinder bores
106
, the jig
111
is disengaged from the pistons
107
. This is because the jig
111
is no longer necessary and will hinder the further insertion of the pistons
107
.
The jig
111
is formed by separable members that are moved in the radial direction to release the pistons
107
. The jig
111
may be an integrated member that is moved in the direction of the axis L
1
to release the pistons
107
.
As illustrated by dotted lines in
FIG. 9
, a wall
109
, which defines the crank chamber
103
, extends from the cylinder block
102
in some compressors. In such a compressor, the pistons
107
cannot be installed by using the jig
111
. That is, the jig
111
interferes with the wall
109
before the pistons
107
reach the cylinder bores
106
. The piston assembly Pa therefore cannot be moved closer to the cylinder block
102
. Thus, it is difficult to automate the installation of the pistons
107
in a compressor if the wall
109
extends by a significant axial distance from the cylinder block
102
. In this case, the pistons
107
must be manually installed, which increases the costs.
If the diameter of the wall
109
is increased such that the jig
111
does not interfere with the wall
109
, the pistons
107
can be installed by the jig
111
. In other words, the assembly of the pistons
107
can be automated. However, the increased diameter of the wall
109
increases the size of the compressor. Since the compressor is located in a vehicle engine compartment, in which a number of other auxiliary components are located, the size of the compressor must be as small as possible.
SUMMARY OF THE INVENTION
Accordingly, it is an objective of the present invention to provide a method and a positioning jig that facilitate automation of installation of pistons in cylinder bores.
To achieve the above objective, the present invention provides a method for installing a piston in a cylinder bore formed in a cylinder block of a fluid machine. The method includes arranging the piston on one end of the cylinder block and a positioning jig on the other end of the cylinder block, inserting the positioning jig into the cylinder bore such that part of the positioning jig protrudes from the cylinder bore toward the piston, engaging the protruding part of the positioning jig with the piston to determine the position of the piston, inserting the piston into the cylinder bore while maintaining the engagement between the jig and the piston, and removing the positioning jig from the cylinder block.
The present invention further provides a positioning jig used for installing a piston in a cylinder bore formed in a cylinder block. The jig comprises a positioning member. The positioning member is inserted into the cylinder bore and protrudes from the cylinder bore. The positioning member determines the position of the piston. A positioning projection is located substantially on the axis of the positioning member. When a distal end surface of the positioning member is pressed against a corresponding end surface of the piston, the positioning projection is inserted into a recess formed substantially on the axis of the piston to align the axis of the piston with the axis of the cylinder bore.
Other aspects and advantages of the invention will become apparent from the following description, taken in conjunction with the accompanying drawings, illustrating by way of example the principles of the invention.


REFERENCES:
patent: 4197627 (1980-04-01), Hirabayashi et al.
patent: 5237739 (1993-08-01), Clark
patent: 5369878 (1994-12-01), Tsuji et al.
patent: 5884906 (1999-03-01), Morse
patent: 6209444 (2001-04-01), Murakami et al.
patent: 8-219012 (1996-08-01), None
patent: 9-310677 (1997-12-01), None
patent: 10-159725 (1998-06-01), None
patent: 10-318129 (1998-12-01), None

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