Information
-
Patent Grant
-
6546841
-
Patent Number
6,546,841
-
Date Filed
Thursday, March 8, 200123 years ago
-
Date Issued
Tuesday, April 15, 200321 years ago
-
Inventors
-
Original Assignees
-
Examiners
- Look; Edward K.
- Lazo; Thomas E.
Agents
-
CPC
-
US Classifications
Field of Search
US
- 092 122
- 092 71
- 092 165 PR
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International Classifications
-
Abstract
A piston includes an engagement portion that engages with a swash plate. The engagement portion is provided with a pair of arm portions and a coupling portion for coupling base ends of the arm portions each other. An axial rib extending in the axial direction is integrally provided in a central part of a back surface of the coupling portion in the width direction orthogonal to a central axis of a head portion of the piston. An accommodation groove is formed on an inner circumferential surface of a cylinder bore corresponding to the axial rib, such that the axial rib does not interfere with the cylinder bore when the piston moves to the top dead center.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a swash plate compressor and a piston therefor.
2. Description of the Related Art
A piston of a swash plate compressor is provided with an engagement portion for engaging with a swash plate. The engagement portion is typically provided with a pair of arm portions extending in parallel to each other and a coupling portion for coupling base ends of the arm portions each other. The coupling portion crosses over an outer circumference part of the swash plate, and the pair of arms engage with both surfaces of the swash plate via shoes, respectively. The coupling portion of the engagement portion receives bending moment when the swash plate compressor is activated. The piston is provided with an engagement portion and a head portion integrally. When the swash plate compressor is activated, the head portion reciprocatingly moves within a cylinder bore. Then, a force acts in the direction of forcing one of the pair of arm portions to move away from the other based on an inertial force acting on the head portion and a frictional force between an outer circumferential surface of the head portion and an inner circumferential surface of the cylinder bore, and bending moment acts in the direction of bending the coupling portion convexly toward the swash plate side.
The bending moment repeatedly acts a large number of times, which tends to cause fatigue fracture in the engagement portion, and therefore is a factor behind the decrease of durability of the piston. In order to improve the durability, it is sufficient to increase bending strength of the coupling portion. However, an attempt to increase the bending strength makes the piston heavier, and requirement of lightening the piston cannot be satisfied.
In addition, in order to increase the bending strength of the coupling portion, it is necessary to make a section modulus of a transverse section shape of the coupling portion larger. For this purpose, it is effective to make the coupling portion thicker. However, since the coupling portion is for coupling the pair of arm portions through a space between an outer circumferential surface of the swash plate and an inner circumferential surface of a housing, it is necessary to either making a diameter of the swash plate smaller or making a diameter of the housing larger to make the coupling portion thicker, both of which are not preferable.
SUMMARY OF THE INVENTION
The present invention has been devised in view of the above and other drawbacks, and it is an object of the present invention to provide a swash plate compressor and a piston therefor that are capable of at least one of increasing bending strength of a coupling portion to be increased while avoiding increasing weight of the piston as much as possible, and increasing a section modulus of the coupling portion without necessitating decrease of a diameter of a swash plate and increase of a diameter of a housing.
A piston for a swash plate compressor in accordance with the present invention is provided with a head portion to be fitted in a cylinder bore and an engagement portion, integrally formed with the head portion, which has a pair of arm portions and a coupling portion for coupling base ends of the arm portions each other and engages with a swash plate while crossing over a circumference part of the swash plate. The engagement portion is provided with a protruding portion that protrudes radially outwardly from a back surface on the opposite side of a swash plate side of the coupling portion.
The protruding portion may include an axial rib extending in a direction parallel to a central axis of the head portion on the back surface on the opposite side of the swash plate side of the coupling portion.
In addition, a swash plate compressor in accordance with the present invention is provided with the above-mentioned piston for a swash plate compressor, a housing having a cylinder bore which is fitted in the head portion of the piston and forms an accommodating recess capable of accommodating the protruding portion on the inner circumferential surface, and a swash plate for reciprocatingly moving the piston by converting its rotational motion about a rotation axis into the reciprocating motion of the piston while engaging with the engagement portion and inclining with respect to the rotation axis.
BRIEF DESCRIPTION OF THE DRAWINGS
In the accompanying drawings:
FIG. 1
is a front sectional view showing a swash plate compressor in accordance with an embodiment of the present invention;
FIG. 2
is a perspective view showing a cylinder block of the swash plate compressor of
FIG. 1
;
FIG. 3
is a perspective view showing a piston of the swash plate compressor of
FIG. 1
;
FIG. 4
is a front sectional view showing a structure around the piston of
FIG. 1
;
FIG. 5
is a sectional view taken away on the line A—A of
FIG. 4
;
FIG. 6
is a side sectional view showing a coupling portion of a piston being another embodiment of the present invention;
FIG. 7
is a side sectional view showing a coupling portion of a piston being further another embodiment of the present invention;
FIG. 8
is a side sectional view showing a coupling portion of a piston being further another embodiment of the present invention;
FIG. 9
is a side sectional view showing a coupling portion of a piston being further another embodiment of the present invention; and
FIG. 10
is a side sectional view showing a coupling portion of a piston being further another embodiment of the present invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
An example of a swash-plate compressor which is used in an automotive air conditioning device and constitutes an embodiment of the present invention, will be described with reference to the accompanying drawings.
FIGS. 1 and 2
show a swash-plate compressor according to the present embodiment. In
FIG. 1
, a reference numeral
10
denotes a cylinder block. A plurality of cylinder bores
12
(seven in the example figures) are disposed at an equal angular interval on a circumference about a central axis M of the cylinder block
10
, and the central axis of the cylinder bores extend parallel to the central axis M. In each of the cylinder bores
12
, a single-headed piston
14
(hereafter referred to simply as a piston
14
) is disposed to make a reciprocating motion. A front housing
16
is attached to one end surface of the cylinder block
10
in the axial direction (i.e. the left side end surface in
FIG. 1
, referred to as a front end surface), and a rear housing
18
is attached via a valve plate
20
to the other end surface (the right side end surface in
FIG. 1
, referred to as a rear end surface). The front housing
16
, the rear housing
18
, the cylinder block
10
constitute a housing assembly of the swash-plate compressor. A suction chamber
22
and a discharge chamber
24
are defined between the rear housing
18
and the valve plate
20
, which are respectively connected through an inlet
26
and a outlet
28
to a refrigerating circuit not shown. The valve plate
20
is provided with suction ports
32
, suction valves
34
, discharge ports
36
, discharge valves
38
and the like.
A rotary shaft
50
is rotatably provided to extend on and along a rotation axis, which is the central axis M of the cylinder block
10
. The rotary shaft
50
is supported at its ends through bearings to the front housing
16
and the cylinder block
10
. A central support hole
56
is formed through a central portion of the cylinder block
10
, and the rotary shaft
50
is supported to the central support hole
56
. The front housing
16
side end portion of the rotary shaft
50
is connected via a clutch mechanism such as an electromagnetic clutch to an unillustrated automotive engine serving as an external drive source. Therefore, when the engine is started to connect the rotary shaft
50
to the engine through the clutch mechanism, the rotary shaft
50
per se is rotated about its own axis.
A swash plate
60
is attached to the rotary shaft
50
relatively movably in the axial direction and inclinably. The swash plate
60
is formed with a central through hole
61
passing through the central line, and the rotary shaft
50
is allowed to penetrate the central through hole
61
. The central hole
61
has a gradually increasing diameter at each open end thereof. A rotary disk
62
, serving as a rotation transmitting member, is fixed to the rotary shaft
50
, and engaged with the front housing
16
via a thrust bearing
64
. By a hinge mechanism
66
, the swash plate
60
is rotated integrally with the rotary shaft
50
, and permitted to be inclined along with the axial movement thereof. The hinge mechanism
66
includes a pair of support arms
67
fixedly provided to the rotary disk
62
, a pair of guide pins
69
fixedly provided to the swash plate
60
and slidably fitted to a pair of guide holes
68
of the respective support arms
67
, the central hole
61
of the swash plate
60
, and an outer circumferential surface of the rotary shaft
50
. In the present embodiment, the rotary shaft
50
, the hinge mechanism
66
constituting the rotation transmitting device, etc. contribute a swash plate driving device. The swash plate driving device and the swash plate
60
contribute a reciprocating drive device for reciprocatingly moving the piston
14
.
The piston
14
is designed as a hollow piston, and includes an engagement portion
70
for engagement with the swash plate
60
, and a hollow head portion
72
provided integrally with the engagement portion
70
and fitted into the cylinder bore
12
. The swash plate
60
is engaged with a groove
74
formed in the engagement portion
70
through a pair of semi-spherical shoes
76
. The semi-spherical shoes
76
have spherical portions slidably held by the engagement portion
70
, and planar portions that are contacted with the respective surfaces of the swash plate
60
to slidably hold and clamp the outer circumferential portion of the swash plate
60
therebetween. The shape of the piston
14
will be described in detail later.
The rotational motion of the swash plate
60
is converted, through the shoes
76
, into the linear reciprocating motion of the piston
14
. During the suction process in which the piston
14
is moved from an upper dead center to a lower dead center, the refrigerant gas within the suction chamber
22
is sucked via the suction port
32
and the suction valve
34
into the cylinder bore
12
. During the compression process in which the piston
14
is moved from the lower dead center to the upper dead center, the refrigerant gas in the cylinder bore
12
is compressed and then discharged via the discharge port
36
and the discharge valve
38
to the discharge chamber
24
. In association with the compression of the refrigerant gas, the axial compression reaction force acts on the piston
14
. The compression reaction force is received through the piston
14
, the swash plate
60
, the rotary plate
62
and the thrust bearing
64
by the front housing
16
. The engagement portion
70
of the piston
14
is provided with a rotation regulating portion
78
(see
FIG. 3
) integrally. The rotation regulating portion
78
, when contacted with the inner circumferential surface of the front housing
16
, restricts the rotation of the piston
14
about the central axis to avoid the interference between the piston
14
and the swash plate
60
. The shape of the rotation regulating portion
78
will be described in detail later.
A supply passage
80
is provided to penetrate through the cylinder block
10
. By this supply passage
80
, the discharge chamber
24
is connected to a swash plate chamber
86
formed between the front housing
16
and the cylinder block
10
. A capacity control valve
90
is provided at a midway of the supply passage
80
. The capacity control valve
90
is an electromagnetic valve, and a solenoid
92
is energized and de-energized by a control device (not shown) mainly constructed by a computer. Depending on information of the cooling load, etc., the supplied current value is controlled, to thereby adjust the opening degree of the capacity control valve
90
.
A bleeding passage
100
is provided in the interior of the rotary shaft
50
. The bleeding passage
100
is opened to the central support hole
56
at one end thereof, and opened to the swash plate chamber
86
at the other end thereof. The central support hole
56
is communicated via a communication bore
104
with the suction chamber
22
.
The swash-plate compressor according to the present embodiment is designed as a variable capacity type, and uses the discharge chamber
24
and the suction chamber
22
as a high pressure source and a low pressure source, respectively, so that a pressure difference therebetween is utilized to control the pressure within the swash plate chamber
86
. This adjusts a pressure difference between the pressure in the cylinder bore
12
serving as the compression chamber and the pressure in the swash plate chamber
86
, which are respectively acting on the front and rear of the piston
14
, to thereby change an inclined angle of the swash plate
60
, change the stroke of the piston
14
and adjust the discharge capacity of the compressor. More specifically, under the control of the capacity control valve
90
, the swash plate chamber
86
is selectively communicated with and isolated from the discharge chamber
24
so that the pressure in the swash plate chamber
86
is controlled. In the de-energizing state of the solenoid
92
, the capacity control valve
90
is fully opened so that the supply passage
80
is put into a communicated state, in which the high pressure refrigerant gas in the discharge chamber
24
is supplied to the swash plate chamber
86
. Accordingly, the pressure within the swash plate chamber
86
is higher and thus the inclined angle of the swash plate
60
is minimal. When the inclined angle of the swash plate
60
is minimal, the volume varying ratio of the compression chamber by the piston
14
, which is reciprocatingly moved in association with the rotation of the swash plate
60
, is small, and thus the discharge capacity of the compressor is minimal. In the energizing state of the solenoid
92
, as the opening degree of the capacity control valve
90
is smaller (including zero) by increasing the supplied current value, the supplied quantity of the high pressure refrigerant gas in the discharge chamber
24
to the swash plate chamber
86
is smaller, and the refrigerant gas within the swash plate chamber
86
is released via the bleeding passage
100
and the communication bore
104
to the suction chamber
22
. Accordingly, the pressure in the swash plate chamber
86
is reduced. In association therewith, the inclined angle of the swash plate
60
is made larger to increase the volume varying ratio of the compression chamber by the piston
14
, thereby increasing the discharge capacity of the compressor. When the supply passage
80
is interrupted due to the energizing of the solenoid
92
, the high pressure refrigerant gas in the discharge chamber
24
is not supplied to the swash plate chamber
86
, so that the inclined angle of the swash plate
60
is maximum. Accordingly, the discharge capacity of the compressor becomes maximum. The maximum inclined angle of the swash plate
60
is defined by the contact of a stopper
106
provided to the swash plate
60
with the rotary plate
62
, and the minimal inclined angle is defined by the contact of the swash plate
60
with a stopper
107
provided onto the rotary shaft
50
. The supply passage
80
, the swash plate chamber
86
, the capacity control valve
90
, the bleeding passage
100
, the communication bore
104
, the control device, etc. constitute an swash plate inclination control device or a discharge capacity control device.
Between the swash plate
60
and the rotary plate
62
, a compression coil spring
108
is disposed as an elastic member that is a kind of a biasing device, and the swash plate
60
is biased toward a position in which the swash plate
60
abuts the stopper
107
to take a posture substantially perpendicular to the central axis M of the cylinder block
10
. When operation of the compressor is stopped, the swash plate
60
is caused to abut the stopper
107
by a biasing force of the spring
108
, and put in a state for standing by for re-activation. At the end on the rotary plate
62
side of the central hole
61
of the swash plate
60
, a recess
110
is formed with a diameter larger than the outer diameter of the central holes
61
. When the swash plate
60
is inclined to a maximum angle of inclination, an end of the spring
108
is received in a receiving surface
112
of the recess
110
which is perpendicular to the central axis M, and when the swash plate
60
is inclined to a minimum angle of inclination, the end of the spring
108
is received in a receiving surface
114
of the recess
110
which is perpendicular to the central axis M.
The cylinder block
10
and the piston
14
is made of an aluminum alloy that is a kind of metal, and fluorocarbon resin coating is applied to the outer circumferential surface of the piston
14
. When coasted with a fluorocarbon resin, a clearance between the piston
14
and the cylinder bore
12
can be as narrow as possible while preventing seizure by avoiding direct contact with a similar kind metal. Further, the cylinder block
10
and the piston
14
are preferably those of aluminum silicon series alloy. However, materials of the cylinder block
10
and the piston
14
, materials for a coating layer and the like are not limited to the above-mentioned materials, but may be any other materials.
The piston
14
will be described more in detail.
An end of the engagement portion
70
of the piston
14
on a side distant from the head portion
72
is generally formed in U shape by the formation of the groove as shown in
FIG. 4
, and is provided with a pair of arm portions
120
and
122
extending in the direction perpendicular to the central axis of the head portion
72
of the piston
14
and a coupling section
124
for coupling base ends of the arm portions
120
and
122
. Recesses
128
are formed on opposing sides of the arm portions
120
and
122
, respectively. Inner surfaces of the recesses
128
are formed in a concave spherical surface shape. The pair of shoes
76
contact both the front and back sides of the outer circumference part of the swash plate
60
, and hold the swash plate
60
and, at the same time, are retained by the recesses
128
. The head portion
72
is made as a hollow head portion provided with a bottomed cylindrical portion
130
that opens at one end and a closure member
132
for closing an opening of the bottomed cylindrical portion
130
, thereby reducing weight. The cylindrical portion
130
configuring a main part of the head portion
72
is formed integrally with the arm portion
122
side of the engagement portion
70
as its bottom wall part.
As shown in
FIG. 5
, an inner surface
138
on a side of the coupling portion
124
of the piston
14
with which the swash plate
60
is engaged and a back surface
140
of the other side are both formed as partially cylindrical surfaces that are convex outwardly in the radial direction. An axial rib
142
extending in parallel to the central axis of the head portion
72
is integrally provided in a central part in the width direction orthogonal with the axial direction of the back surface
140
. The coupling portion
124
is reinforced by the axial rib
142
. The axial rib
142
has a transverse sectional shape formed in rectangular smaller than the width of the coupling portion
124
, and protrudes radially outwardly than an outer circumferential surface
144
of the head portion
72
. In
FIGS. 4 and 5
, a clearance between an inner circumferential surface of the cylinder bore
12
and the outer circumferential surface
144
of the head portion
72
is exaggerated. As shown in
FIG. 3
, the rotation regulating portion
78
is integrally formed with the engagement portion
70
protruding radially outwardlly than the back surface
140
on the base end side, coupled by the coupling portion
124
on the side of the arm portion
120
. The width of the rotation regulating portion
78
(a dimension in the tangent direction with respect to the inner circumferential surface of the front housing
16
) is formed larger than the diameter of the head portion
72
. Rotation regulating surfaces
146
are formed in two places isolatedly in the circumferential direction, on a surface that is a protruding surface of the rotation regulating portion
78
and opposes the inner circumferential surface of the front housing
16
. The rotation regulating surfaces
146
form partially cylindrical surfaces defined by a center of curvature and a radius of curvature that are different from the outer circumferential surface
144
of the head portion
72
. The radius of curvature of the rotation regulating surface
146
is made larger than that of the outer circumferential surface
144
. Rotation of the piston
14
is regulated as described before by the rotation regulating portion
78
contacting the inner circumferential surface of the front housing
16
at a part of the rotation regulation surface
146
that is most distant from the central axis of the piston
14
.
As shown in
FIG. 2
, in the cylinder block
10
, an extension portion
150
is formed on a circumferential wall of each cylinder bore
12
. The outer circumferential side part of the extension portion
150
distant from the central axis M axially extends longer toward the swash plate chamber
86
side than the inner circumferential side part close to the central axis M. A front end face
152
is defined by coupling each extension portion
150
mutually to be positioned on an identical plane, and the front housing
16
is attached on the front end face
152
. The inner circumferential surface of the cylinder bore
12
has an inner circumferential surface
154
forming a complete cylindrical surface on the rear housing
18
side and an inner circumferential surface
156
forming a partially cylindrical surface on the front housing
16
side. An accommodation groove
160
extending axially is formed in the inner circumferential surface
156
of the cylinder bore
12
, open to the front end surface
152
, and extends to the midway of the inner circumferential surface
154
. The accommodation groove
160
is formed as a rectangular groove with a width larger than the width of the axial rib
142
and smaller than the width of the inner circumferential surface
156
. In addition, as shown in
FIG. 5
, a depth of the accommodation groove
160
to a bottom surface
162
is made a size that leaves a small clearance between the bottom surface
162
and an outer surface
166
of the axial rib
142
opposing the bottom surface
162
. Further, in
FIGS. 1 through 5
, the sizes of the axial rib
142
and the accommodation groove
160
and the clearance between them are illustrated exaggeratedly for easier understanding. As described before, since rotation of the piston
14
around the central axis is regulated by the contact of the rotation regulating surface
146
of the rotation regulating portion
78
and the inner circumferential surface of the front housing
16
, the side of the axial rib
142
and the side of the accommodation groove
160
do not contact, thus the clearance between them is secured and movement of the axial rib
142
in the accommodation groove
160
is not prevented.
According to the embodiment, bending strength of the coupling portion
124
can be larger and durability of the piston
14
can be improved while avoiding increase of the weight of the piston
14
as much as possible by the formation of the axial rib
142
. Moreover, by forming in a part of the cylinder bore
12
the accommodation groove
160
that can accommodate the axial rib
142
, interference between the axial rib
142
and the circumferential wall of the cylinder bore
12
can be avoided, when the piston
14
moves to the top dead center, without making the circumferential surface of the cylinder bore
12
larger in diameter. In addition, the sliding characteristics of the piston
14
can be improved. When the axial rib
142
is detached from the accommodation groove
160
at the last stage of suction stroke of the piston
14
, lubricating oil existing in the swash plate chamber
86
in the form of mist or spray enters the accommodation groove
160
. In the next compression stroke the axial rib
142
is inserted in the accommodation groove
160
again, and the lubricant oil in the accommodation groove
160
is supplied to the space between the inner circumferential surface
154
and the outer circumferential surface
144
of the head portion
72
in line with the decrease of the volume in the accommodation groove
160
. Moreover, by increasing the length of the circumferential wall of the cylinder bore
12
on the distant side to the axis M with the extension portion
150
, the fitting length of the piston
14
and the cylinder bore
12
at the bottom dead center of the piston
14
on the side can be made larger. Thus, since inclination of the piston
14
to the direction in which the engagement portion
70
moves radially outwardly can be well avoided, the non-returning of the piston
14
into the cylinder bore
12
due to excessive friction resistance, and an obstruction to return of the swash plate
60
to the minimum angle of inclination can be avoided. Further, since the extension portion
150
is not formed on the radially close side to the axis M, movement of the swash plate
60
from the maximum inclination position to the minimum inclination position is not prevented.
The axial rib
142
in this embodiment is an example of a protruding portion, and the protruding portion may take various forms and dimensions, and other number of protruding portions may be disposed. In addition, the accommodation groove
160
formed in the cylinder bore
12
is an example of an accommodation recess, a form of the accommodation recess may also be an appropriate one corresponding to a shape and a dimension of the protruding portion. For example, an axial rib as the protruding portion can be of various dimensions suitable for the dimension of the coupling portion
124
, and, as shown in
FIG. 6
, may be an axial rib
180
with the dimension in the width direction of the coupling portion
124
larger than the dimension (height) in the radial direction. Conversely, as shown in
FIG. 7
, the axial rib may be an axial rib
190
with the dimension in the radial direction larger than the dimension in the width direction. The number of axial ribs to be disposed may be two other than one, and as shown in
FIG. 8
, two axial ribs
200
may be provided in positions apart from each other in the circumferential direction of the back surface
140
. This is effective when it is difficult to form a rib in a central part in the width direction due to a structure of a piston. In addition, as shown in
FIG. 9
, a protruding portion
210
in a partially cylindrical shape may be formed which protrudes radially outwardly than the outer circumferential surface
144
of the head portion
72
over the entire outer circumference of the back surface
140
of the coupling portion
124
. Moreover, as shown in
FIG. 10
, the present invention can be applied to a piston with an inner surface
222
of a coupling portion
220
forming a plane.
In the embodiments shown in
FIGS. 1 through 5
, the piston
14
is of the configuration in which neither the outer surface
166
of the axial rib
142
nor the back surface
140
of the coupling portion
124
is guided on the inner circumferential surface of the cylinder bore
12
. However, the piston
14
may be configured such that the outer surface
166
is guided on the bottom surface
162
of the accommodation groove
160
, or a part on the head portion
72
side of the back surface
140
of the coupling portion
124
is guided on the inner circumferential surface of the cylinder bore
12
. In this way, since the piston
14
is guided not only on the outer circumferential surface
144
of the head portion
72
but also on the outer surface
166
or the back surface
140
, the piston
14
can slide in the cylinder bore
12
more steadily.
The present invention may be applied to a piston of a configuration in which a closure member and an engagement portion are integrally formed and an opening of a bottomed cylindrical member forming a main part of a head portion is closed by the closure member, or a piston of a configuration in which a head portion is separated at the central part in the axial direction and has a portion provided with an engagement portion and a portion not provided with an engagement portion.
The present invention is applied to a variable capacity swash plate compressor. The weight of the pistons affects on the discharge capacity control of such a compressor, so it is effective to reduce the weight of the piston while reinforcing the piston. But the type of compressor is not limited.
A structure of a swash plate compressor is not limited to those in the above-mentioned embodiments, but may take other forms. For example, the capacity control valve
90
is not indispensable, and an operating valve can be provided which is mechanically opened and closed based on a difference between a pressure in the discharge chamber
24
and a pressure in the swash plate chamber
86
. In addition, instead of the capacity control valve
90
, or together with the capacity control valve
90
, an electromagnetic control valve similar to the capacity control valve
90
may be provided in the midway of the bleeding passage
100
, or an operating valve may be provided which is mechanically opened and closed based on a difference between a pressure in the swash plate chamber
86
and a pressure in the suction chamber
22
.
The present invention may be applied to a double-headed piston having head portions on both sides of an engagement portion with a swash plate, or can be applied to a piston for a fixed capacity swash plate compressor.
Some embodiments of the present invention have been described in detail, but the embodiments are merely examples. The present invention may be implemented in a form in which various alterations or improvements are applied based on knowledge of those having ordinary skills in the art.
Claims
- 1. A piston for a swash plate compressor, comprising:a head portion to be fitted in a cylinder bore; and an engagement portion, integrally formed with said head portion, which has a pair of arm portions and a coupling portion for coupling base ends of said arm portions to each other and engages with a swash plate while crossing over a circumference part of the swash plate, wherein said engagement portion is provided with a rotation regulating portion and a protruding portion, the protruding portion is separate from said rotation regulating portion and protrudes radially outwardly from a back surface on the opposite side of a swash plate side of the coupling portion.
- 2. A piston for a swash plate compressor according to claim 1, wherein the protruding portion may include an axial rib extending in a direction parallel to a central axis of said head portion on the back surface on the opposite side of the swash plate side of the coupling portion.
- 3. A piston for a swash plate compressor according to claim 2, wherein the number of the axial ribs is one, and the axial rib is provided in the center of the back surface of the coupling portion.
- 4. A piston for a swash plate compressor according to claim 2, wherein the number of the axial ribs is two, and the axial ribs are provided apart from each other extending on both sides of the center of the back surface of the coupling portion.
- 5. A piston for a swash plate compressor according to claim 2, wherein the number of axial ribs is one, and the axial rib is provided over the entire outer circumference of the back surface of the coupling portion.
- 6. A piston for a swash plate compressor according to claim 1, wherein an inner surface of the coupling portion forms a plane.
- 7. A swash plate compressor, comprising:a piston according to claim 1; a housing having a cylinder bore, said cylinder bore is fitted in said head portion of said piston, and forms an accommodating recess capable of accommodating the protruding portion on the inner circumferential surface; and a swash plate for reciprocatingly moving said piston by converting its rotational motion about a rotation axis into the reciprocating motion of the piston while engaging with said engagement portion and inclining with respect to the rotation axis.
- 8. A swash plate compressor according to claim 7, further comprising:a swash plate driving device that supports said swash plate in a state in which an inclined angle of the swash plate with respect to the rotation axis is variable and rotates said swash plate; an inclined angle control device for controlling the inclined angle of said swash plate by controlling a pressure in a swash plate chamber that is formed in said housing and accommodates said swash plate; and a biasing device for biasing said swash plate toward a position substantially perpendicular to the rotation axis, wherein three or more cylinder bores are provided around the rotation axis at an equal angular interval and said head portion of said piston is fitted in the respective cylinder bores, and wherein circumferential walls of the cylinder bores distant from the rotation axis is extended longer to the swash plate chamber side than circumferential walls of the cylinder bores close to the rotation axis, and accommodating recesses are formed at least in the extended walls.
- 9. A piston for a swash plate compressor, comprising:a head portion to be fitted in a cylinder bore; and an engagement portion, integrally formed with said head portion, which has a pair of arm portions and a coupling portion for coupling base ends of said arm portions to each other and engages with a swash plate while crossing over a circumference part of the swash plate, wherein said engagement portion is provided with a protruding portion that protrudes radially outwardly from a back surface on the opposite side of a swash plate side of the coupling portion, said protruding portion is sized and configured to reciprocatingly move within a cylinder bore in a non-contacting manner during operation of a swash plate compressor.
- 10. A compressor, comprising:a housing comprising a cylinder bore, said cylinder bore including a recess formed in an inner circumferential surface thereof; a piston comprising: a head portion to be fitted within said cylinder bore; and an engagement portion, integrally formed with said head portion, which has a pair of arm portions and a coupling portion for coupling base ends of said arm portions with each other, and which engages with a swash plate while crossing over a circumference part of the swash plate, wherein said engagement portion is provided with a protruding portion that protrudes radially outwardly, said protruding portion reciprocatingly moves within said recess; and a swash plate for reciprocatingly moving said piston by converting its rotational motion about a rotation axis into a reciprocating motion while engaging with said engagement portion and inclining with respect to the rotation axis.
Priority Claims (1)
Number |
Date |
Country |
Kind |
2000-076013 |
Mar 2000 |
JP |
|
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Date |
Country |
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JP |