U.S. patent application number 10/034100 was filed with the patent office on 2003-07-03 for piston anti-rotation mechanism for a swash plate compressor.
Invention is credited to Khetarpal, Vipen, Pitla, Srinivas S..
Application Number | 20030121413 10/034100 |
Document ID | / |
Family ID | 21874305 |
Filed Date | 2003-07-03 |
United States Patent
Application |
20030121413 |
Kind Code |
A1 |
Pitla, Srinivas S. ; et
al. |
July 3, 2003 |
Piston anti-rotation mechanism for a swash plate compressor
Abstract
The present involves an anti-rotation piston for a swash plate
compressor assembly having a piston-receiving bore and an
anti-rotation groove formed adjacently therein. The anti-rotation
piston comprises a body and a skirt extending from the body. The
body has a first radius of curvature and first and second ends. The
body complements the bore so that the body is slideably moveable
within the bore. The skirt extends from the second end of the body
and has an arcuate outer surface which complements the groove so
that the skirt is slideably moveable along the groove. The skirt
has a second radius of curvature which is greater than the first
radius of curvature. The second radius of curvature is offset from
the first radius of curvature so that the body and the skirt have
differing axes of rotation which prevents the piston from
rotating.
Inventors: |
Pitla, Srinivas S.;
(Farmington Hills, MI) ; Khetarpal, Vipen; (Novi,
MI) |
Correspondence
Address: |
BRINKS HOFER GILSON & LIONE
P.O. BOX 10395
CHICAGO
IL
60611
US
|
Family ID: |
21874305 |
Appl. No.: |
10/034100 |
Filed: |
December 28, 2001 |
Current U.S.
Class: |
92/71 |
Current CPC
Class: |
F04B 27/1081 20130101;
F04B 27/0878 20130101 |
Class at
Publication: |
92/71 |
International
Class: |
F01B 003/00 |
Claims
1. A piston anti-rotation mechanism for a swash plate compressor
assembly, the piston anti-rotation mechanism comprising: a swash
plate compressor having a piston-receiving bore and an
anti-rotation groove formed adjacently therein; and an
anti-rotation piston having a body and a skirt extending therefrom,
the body having a first radius of curvature and first and second
ends, the body complementing the bore so that the body is slideably
movable within the bore, the skirt extending from the second end of
the body and having an arcuate outer surface complementing the
groove so that the skirt is slideably movable along the groove, the
skirt having a second radius of curvature being offset from the
first radius of curvature so that the body and the skirt have
differing axes of rotation preventing piston rotation.
2. The piston anti-rotation mechanism of claim 1 wherein the second
radius of curvature is greater than the first radius of curvature
and wherein the swash plate compressor further comprises: a front
head having a drive shaft side and an inner wall extending from the
drive shaft side to an open end to define a crank case, the inner
wall having the anti-rotation groove formed thereon and extending
to the open end; a cylinder having front and rear ends, the front
end having the piston-receiving bore formed therethrough, the front
end connecting to the open end so that the groove is adjacent the
bore; a drive shaft having first and second portions and rotatably
disposed through the drive shaft side in the front head so that the
first portion is disposed within the crank case; and a swash plate
angularly disposed about the first portion of the drive shaft in
the crank case to angularly rotate the plate with the drive shaft
as the drive shaft rotates.
3. The piston anti-rotation mechanism of claim 2 wherein the skirt
forms a plate-receiving slot through which the swash plate
angularly rotates to slideably move the piston along the
groove.
4. The piston anti-rotation mechanism of claim 3 wherein the
plate-receiving slot is defined by first and second walls having
first and second shoe pockets respectively formed thereon.
5. The piston anti-rotation mechanism of claim 4 further comprising
a shoe disposed in the shoe pocket for receiving the swash plate in
the plate-receiving slot.
6. The piston anti-rotation mechanism of claim 1 wherein the axis
of rotation of the skirt is within the piston.
7. The piston anti-rotation mechanism of claim 6 wherein the axis
of rotation of the skirt is between the inner wall and the axis of
rotation of the body.
8. The piston anti-rotation mechanism of claim 1 wherein the swash
plate compressor assembly includes a plurality of grooves and bores
formed adjacently therein.
9. The piston anti-rotation mechanism of claim 8 further comprising
a plurality of pistons so that each piston is received in a
respective groove and bore of the swash plate compressor
assembly.
10. The piston anti-rotation mechanism of claim 1 wherein the skirt
includes a planar outer surface integrally connected to the arcuate
outer surface having the second radius of curvature.
11. A piston anti-rotation mechanism for a swash plate compressor
assembly, the anti-rotation mechanism comprising: a housing
including an inner wall and a front end connected to the inner wall
defining a crank case, the inner wall having an anti-rotation
groove formed thereon, the front end having a piston-receiving bore
formed therethrough adjacent the groove; and an anti-rotation
piston having a body and a skirt extending from the body, the body
having a first radius of curvature and top and bottom ends, the
body complementing the bore so that the body is slideably movable
within the bore, the skirt extending from the bottom end and having
an arcuate outer surface complementing the groove of the inner wall
so that the skirt is slideably movable along the groove when the
body is disposed in the bore, the skirt having a second radius of
curvature greater than the first radius of curvature and offset
therefrom so that the body and the skirt have differing axes of
rotation preventing rotation of the piston.
12. The anti-rotation mechanism of claim 11 wherein the housing
further comprises: a front head having a drive shaft side and an
inner wall extending from the drive shaft side to an open end to
define a crank case, the inner wall having the anti-rotation groove
formed thereon and extending to the open end; a cylinder having
front and rear ends, the front end having the piston-receiving bore
formed therethrough, the front end connecting to the open end so
that the groove is adjacent the bore; a drive shaft having first
and second portions and rotatably disposed through the drive shaft
side in the front head so that the first portion is disposed within
the crank case; and a swash plate angularly disposed about the
first portion of the drive shaft in the crank case to angularly
rotate the plate with the drive shaft as the drive shaft
rotates.
13. The anti-rotation mechanism of claim 12 wherein the skirt forms
a plate-receiving slot through which the slosh plate angularly
rotates to slideably move the piston along the groove.
14. The anti-rotation mechanism of claim 13 wherein the
plate-receiving slot is defined by first and second walls having
first and second show pockets respectively formed thereon.
15. The anti-rotation mechanism of claim 14 further comprising a
shoe disposed in the shoe pocket for receiving the swash plate.
16. The anti-rotation mechanism of claim 11 wherein the axis of
rotation of the skirt is within the piston.
17. The anti-rotation mechanism of claim 16 wherein the axis of
rotation of the skirt is between the inner wall and the axis of
rotation of the body.
18. The anti-rotation mechanism of claim 11 wherein the compressor
assembly includes a plurality of grooves and bores formed
adjacently therein.
19. The anti-rotation mechanism of claim 18 further comprising a
plurality of pistons so that each piston is received in a
respective groove and bore of the compressor assembly.
20. The anti-rotation mechanism of claim 11 wherein the skirt of
the piston includes a planar outer surface integrally connected to
the arcuate outer surface having the second radius of
curvature.
21. A swash plate compressor assembly having a piston anti-rotation
mechanism, the assembly comprising: a front head having a drive
shaft side and an inner wail extending from the drive shaft side to
an open end to define a crank case, the inner wall having an
anti-rotation groove formed thereon and extending to the open end;
a cylinder having front and rear ends, the front end having a
piston-receiving bore formed therethrough, the front end connecting
to the open end so that the groove is adjacent the bore; a drive
shaft having first and second portions and rotatably disposed
through the drive shaft side in the front head so that the first
portion is disposed within the crank case; a swash plate angularly
disposed about the first portion of the drive shaft in the crank
case to angularly rotate the plate with the drive shaft as the
drive shaft rotates; and an anti-rotation piston having a body and
a skirt extending from the body, the body having a first radius of
curvature and first and second ends, the body complementing the
bore so that the body is slideably movable within the bore, the
skirt extending from the second end and having an arcuate outer
surface complementing the groove of the inner wall so that the
skirt is slideably movable along the groove, the skirt having a
second radius of curvature greater than the first radius of
curvature and offset therefrom so that the body and the skirt have
differing axes of rotation preventing piston rotation, the skirt
forming a plate-receiving slot through which the swash plate
angularly rotates to slideably move the piston along the
groove.
22. The assembly of claim 21 wherein the plate-receiving slot is
defined by first and second walls having first and second shoe
pockets respectively formed thereon.
23. The assembly of claim 22 further comprising a shoe disposed in
the shoe pocket for receiving the swash plate.
24. The assembly of claim 21 wherein the axis of rotation of the
skirt is within the piston.
25. The assembly of claim 24 wherein the axis of rotation of the
skirt is between the inner wall and the axis of rotation of the
body.
26. The assembly of claim 21 wherein the compressor assembly
includes a plurality of grooves and bores formed adjacently
therein.
27. The assembly of claim 26 further comprising a plurality of
pistons so that each piston is received in a respective groove and
bore of the compressor assembly.
28. The assembly of claim 21 wherein the skirt of the piston
includes a planar outer surface integrally connected to the arcuate
outer surface having the second radius of curvature.
Description
BACKGROUND OF THE INVENTION
[0001] The present invention relates to a piston anti-rotation
mechanism for a reciprocating swash plate compressor assembly.
[0002] Swash plate compressors are known in the art and are widely
used in many industries, such as for climate control systems for
motor vehicles in the automotive industry. Typically, a swash plate
compressor includes a compressor housing which is configured to
receive a rotatable driveshaft and a swash plate angularly disposed
about the driveshaft. The compressor further includes a number of
pistons which are slideably attached to the swash plate so that the
swash plate linearly moves the piston within the compressor as the
swash plate rotationally moves about its axis of rotation.
[0003] In most situations, it is undesirable for the piston to
rotatably move in its bore within the compressor housing. However,
in many situations, the swash plate which slidably attaches to the
piston drags the piston to rotate as well as linearly move within
the compressor. Rotation of the piston causes an undesirable
contact with the swash plate, e.g., an undesirable contact of the
swash plate and a skirt of the piston. Such contact may cause
damage to the piston. Several manufacturers of swash plate
compressors have been challenged in producing anti-rotational
features of pistons within the compressor assembly, while
maintaining high efficiency and low costs. Current swash plate
compressor technology calls for further improvements to be made in
such compressors.
BRIEF SUMMARY OF THE INVENTION
[0004] The present invention provides a swash plate compressor
assembly having a piston anti-rotation mechanism which prevents
pistons disposed within the compressor assembly from rotating
therein. The assembly generally includes a front head having
grooves formed within an inner wall and a cylinder block having
bores formed therein. The cylinder block attaches to the front head
so that the grooves are aligned adjacently with the bores to allow
the pistons to be disposed simultaneously within the bores and the
grooves. Each piston includes a body and a skirt extending from the
body. The body complements the bore and the skirt complements the
groove so that the piston can slide within the compressor assembly.
The body and the groove have differing axes of rotation which are
offset from each other. The offset relationship of the axes and the
complementing dimensions of the piston relative to the groove and
the bore define the anti-rotation mechanism which prevents the
piston from rotating within the compressor assembly as the piston
moves along the groove and the bore.
[0005] The swash plate compressor assembly of the present invention
also provides a cost advantage and improved quality control in
manufacturing the assembly. In one embodiment of the present
invention, the groove and skirt are merely cylindrically shaped
requiring no complex shapes formed by milling or broaching
operations. A typical boring machine can easily bore the grooves
saving time and, in turn, costs.
[0006] These and other advantages, features and benefits of the
invention will become apparent from the drawings, detailed
description and claims which follow.
BRIEF DESCRIPTION OF THE DRAWINGS
[0007] FIG. 1 is a side cross-sectional view of a swash plate
compressor assembly having a piston anti-rotation mechanism in
accordance with one embodiment of the present invention;
[0008] FIG. 2a is a top view of a front head of the compressor
assembly of FIG. 1;
[0009] FIG. 2b is an enlarged view of an anti-rotation groove of
the front head shown in FIG. 2a;
[0010] FIG. 3 is a front perspective view of a cylinder of the
compressor assembly in FIG. 1;
[0011] FIG. 4 is a side perspective view of a first embodiment of
an anti-rotation piston of the compressor assembly;
[0012] FIG. 5 is another side view of the anti-rotation piston in
FIG. 4;
[0013] FIG. 6a is a side environment view of a plurality of
anti-rotation pistons disposed in the front head of the compressor
assembly;
[0014] FIG. 6b is a cross-sectional side view of the compressor
assembly shown in FIG. 6a taken along lines 6-6;
[0015] FIG. 6c is a side view of the anti-rotation piston shown in
FIG. 4 disposed along the anti-rotation groove shown in FIG.
2b;
[0016] FIG. 6d is another cross-sectional side view of the
compressor assembly in FIG. 6a taken along lines 6-6 depicting axes
B and C of the anti-rotation piston.
[0017] FIG. 7a is a top environmental view of the front head of the
compressor assembly having the anti-rotation piston disposed
therein;
[0018] FIG. 7b is an enlarged view of the anti-rotation piston
shown in FIG. 7a;
[0019] FIG. 8 is a side view of a second embodiment of the
anti-rotation piston in accordance with the present invention;
[0020] FIG. 9 is a top view of the anti-rotation piston shown in
FIG. 8;
[0021] FIG. 10 is another side view of the second embodiment of the
anti-rotation piston;
[0022] FIG. 11 is a cross-sectional view of the compressor assembly
housing the second embodiment of the anti-rotation piston;
[0023] FIG. 12a is a top cross-sectional view of the compressor
assembly shown in FIG. 11; and
[0024] FIG. 12b is an enlarged view of the piston anti-rotation
mechanism shown in FIG. 12a.
DETAILED DESCRIPTION OF THE INVENTION
[0025] FIG. 1 illustrates swash plate compressor assembly 10 having
a piston anti-rotation mechanism. As shown, compressor assembly 10
includes a rear head and front head 13 having driveshaft side 16
and inner wall 20 extending from driveshaft side 16 to open end 23
defining crank case 26. FIGS. 1-2b depict inner wall 20 having a
plurality of anti-rotation grooves 30 formed thereon and extending
to open end 23. FIGS. 1 and 3 depict cylinder 33 having front and
rear ends 36, 37. Front end 36 includes a plurality of
piston-receiving bores 40 formed therethrough, wherein front end 36
engages with open end 23 so that one of the anti-rotation grooves
30 is adjacent one of the piston-receiving bores 40. As shown,
assembly 10 further includes driveshaft 43 having first and second
portions 46, 47 and defining axis A of rotation. In this
embodiment, driveshaft 43 is rotatably disposed through driveshaft
side 16 and at the center of front head 13 so that first portion 46
is disposed within crank case 26. Swash plate 50 is angularly
disposed about the first portion 46 of driveshaft 43 in crank case
26. This allows swash plate 50 to be angularly rotated relative to
assembly 10 as driveshaft 43 rotates about axis A.
[0026] FIG. 4 illustrates anti-rotation piston 53, a plurality of
which are configured to be slideably disposed in compressor
assembly 10. As shown, anti-rotation piston 53 includes body 56 and
skirt 60 extending from body 56. Body 56 has first radius 63 of
curvature and first and second ends 66, 67. As shown, body 56
complements piston-receiving bore 40 of cylinder 33 so that body 56
is slideably moveable within bore 40 when disposed in assembly 10.
As shown, skirt 60 extends from second end 67 and has an arcuate
outer surface 70 complementing groove 30 of inner wall 20 so that
skirt 60 is slideably moveable along the groove when disposed in
assembly 10. Skirt 60 further has a second radius 73 of curvature
which is greater than first radius 63 of curvature of body 56.
Second radius 73 and first radius 63 are in non-concentric or in
offset relationship with each other so that body 56 and skirt 60
have differing axes of rotation. Preferably, body 56 is configured
to have axis of rotation B located within piston 53, and skirt 60
is configured to have axis of rotation C located within piston 53
between inner wall 20 and axis of rotation B. The offset
relationship of the axes and the complementing dimensions of the
piston relative to the groove and the bore defines the
anti-rotation mechanism. In operation of compressor assembly 10,
this prevents piston 53 from rotating therein.
[0027] As shown in FIGS. 4 and 5, skirt 60 forms plate-receiving
slot 76 through which swash plate 50 slidably rotates to slideably
move piston 53 along groove 30. Plate-receiving slot 76 is defined
by first and second walls 78, 79 which are integrally connected by
back wall 80. As shown, first wall 78 has first shoe pocket 83
formed thereon, and second wall 79 has second shoe pocket 84 formed
thereon. As shown, shoe 86 is disposed in plate-receiving slot 76
within first and second shoe pockets 83, 84. Thus, swash plate 50
is slidably received between pairs of in shoe 86 during normal
operation of assembly 10.
[0028] FIG. 6a illustrates anti-rotation piston 53 disposed in
compressor assembly 10. As shown in FIGS. 6b and 6c, skirt 60 is
slidably moveable along anti-rotation groove 30 and body 56 is
slidably moveable within piston-receiving bore 40. Arcuate outer
surface 70 complements groove 30 which allows piston 53 to slidably
move along groove 30. Body 56 complements piston-receiving bore 40
such that piston 53 may also slide within bore 40. In operation,
swash plate 50 is angularly rotated about axis A of rotation and is
slidably attached to shoe 86 in plate-receiving slot 76 so that, as
swash plate 50 rotates about axis A of rotation, angular movement
of plate 50 allows piston 53 to linearly move along groove 30 and
bore 40. As shown in FIGS. 6b and 7a-7b, piston 53 is prevented
from rotating about either axis B or axis C, since the axes B, C
are in offset relationship as body 56 complements bore 40 and skirt
60 complements groove 30. This prevents swash plate 50 from
contacting bridge or back wall 80, thereby increasing the longevity
of each of the pistons 53.
[0029] FIGS. 8 and 9 depict a second embodiment of the piston for
the swash plate compressor assembly 10. As shown, anti-rotation
piston 153 includes similar features to anti-rotation piston 53.
For example, body 156, skirt 160, first radius 163, first end 166,
second end 167, and second radius 173 of anti-rotation piston 153
are similar to body 56, skirt 60, first radius 63, first end 66,
second end 67, and second radius 73 of anti-rotation piston 53. As
shown in FIG. 10, outer surface 170 of skirt 160 has arcuate and
planar surfaces. Arcuate surfaces 171, 172 are integrally connected
to each other by planar surface 174. As shown, arcuate surfaces
171, 172 complement the dimensions of anti-rotation groove 30 such
that arcuate surfaces 171, 172 have the same radius of curvature
length as skirt 60, although outer surface 171 does not fully
complement groove 130. As a result, anti-rotation piston 153 weighs
substantially less than anti-rotation piston 53 of the first
embodiment, while maintaining anti-rotation of piston 153 within
assembly 10. Although planar surface 174 may not complement groove
130, arcuate surfaces 171 and 172 prevent piston 153 from rotating
since its axis of rotation C' is offset from axis of rotation B' as
shown. Additionally, arcuate surfaces 171 and 172 complement the
anti-rotation groove to further prevent rotation of piston 153.
[0030] It has been found that the swash plate compressor assembly
of the present invention also provides a cost advantage and quality
control in manufacturing the assembly. As depicted in the figures,
the grooves of the inner walls are simply formed to have a
cylindrical shape which receives the skirt of each piston. This
shape of the grooves is relatively simple or easy to form on the
inner walls with respect to other complex inner wall shapes formed
by milling or broaching operations. With a typical boring machine,
the grooves of the inner walls of the present invention are formed
in a time efficient manner resulting in cost savings.
[0031] While the invention has been described in terms of preferred
embodiments, it will be understood, of course, that the invention
is not limited thereto since modifications may be made by those
skilled in the art, particularly in light of the foregoing
teachings.
* * * * *