U.S. patent application number 09/775075 was filed with the patent office on 2001-09-13 for piston type compressor.
Invention is credited to Iwamori, Hidekazu, Kato, Takayuki, Ohno, Tomomi, Yokota, Masahiro.
Application Number | 20010020414 09/775075 |
Document ID | / |
Family ID | 18553650 |
Filed Date | 2001-09-13 |
United States Patent
Application |
20010020414 |
Kind Code |
A1 |
Iwamori, Hidekazu ; et
al. |
September 13, 2001 |
Piston type compressor
Abstract
The object of the present invention is to propose a compressor
in which rotation of a piston is prevented without affecting a big
unbalanced load to the piston and the manufacture of the piston is
simplified. The compressor comprises a housing having a cylinder
bore therein, a drive shaft, a swash plate as a cam plate and a
piston including a head portion and a neck portion. The housing and
the piston are made of metal such as aluminium or an aluminium
alloy. A rotation preventing member formed separately from the
piston is mounted on the neck portion of the piston. The rotation
preventing member is composed of a pair of rotation preventing
portions, an abutting portion and a pair of caulking portions to
mount to the neck portion. Those are made of metallic material such
as iron series and formed in one body. The rotation preventing
portion prevents the piston from rotating, cooperating with the
contacting portion formed on the inner wall of the housing.
Inventors: |
Iwamori, Hidekazu;
(Kariya-shi, JP) ; Ohno, Tomomi; (Kariya-shi,
JP) ; Kato, Takayuki; (Kariya-shi, JP) ;
Yokota, Masahiro; (Kariya-shi, JP) |
Correspondence
Address: |
MORGAN & FINNEGAN, L.L.P.
345 Park Avenue
New York
NY
10154
US
|
Family ID: |
18553650 |
Appl. No.: |
09/775075 |
Filed: |
February 1, 2001 |
Current U.S.
Class: |
92/71 |
Current CPC
Class: |
F04B 27/0878
20130101 |
Class at
Publication: |
92/71 |
International
Class: |
F01B 003/00 |
Foreign Application Data
Date |
Code |
Application Number |
Feb 4, 2000 |
JP |
2000-028198 |
Claims
What is claimed is:
1. A piston type compressor comprising: a housing having a cylinder
bore therein; a drive shaft rotatably supported in the housing; a
cam plate coupled on the drive shaft to rotate integrally
therewith; a piston being operatively connected to the cam plate
through a pair of shoes; the piston including a head portion and a
neck portion; the head portion of the piston being inserted into
the cylinder bore; and the cam plate converting rotation of the
drive shaft to reciprocating movement of the piston through the
pair of shoes; a rotation preventing member formed separately from
the piston and mounted on the piston; a contacting portion formed
in the housing; and wherein said rotation preventing member
prevents rotation around the axis of the piston, by contacting with
said contacting portion when the piston rotates by a certain
angle.
2. A piston type compressor according to claim 1; wherein said
rotation preventing member being received in the piston; and a
stopper to restrict the relative movement of said rotation
preventing member in the axial direction of the piston is arranged
between said rotation preventing member and the piston.
3. A piston type compressor according to claim 1; wherein said
rotation preventing member is provided with a rotation preventing
portion to prevent rotation in both directions around the axis of
the piston.
4. A piston type compressor according to claim 1; wherein said
rotation preventing member is made of different material from that
of the housing.
5. A piston type compressor according to claim 1; wherein said
rotation preventing member is mounted to the piston by
adhesion.
6. A piston type compressor according to claim 1; wherein said
rotation preventing member includes a plurality of rotation
preventing portions, and they are arranged on the outer surface of
the piston separately in the direction of the rotation of the
piston.
7. A piston type compressor according to claim 2; wherein said
stopper includes a concave portion formed on the piston; and
wherein said rotation preventing member being inserted into said
concave portion loosely.
8. A piston type compressor according to claim 7; wherein said
rotation preventing member has a protruding portion composing said
stopper; and wherein said protruding portion being inserted into
said concave portion of the piston loosely.
Description
BACKGROUND OF THE INVENTION
[0001] The present invention relates to a compressor for use in an
air conditioner for vehicle, especially, a piston type compressor
in which the rotation of the piston is prevented.
[0002] Conventionally, it is common that a rotation preventing
member and the piston are formed integrally. For example, devices
in FIG. 7 and FIG. 8(a) are disclosed in Japanese Unexamined Patent
Publication No. 11-201037.
[0003] A drive shaft 101 is rotatably supported by a housing 102. A
swash plate 13 as a cam plate is coupled with the drive shaft 101
to rotate integrally. A cylinder bore 102a is defined in the
housing 102. A head portion 104a of a single-headed piston 104 is
inserted into the cylinder bore 102a. A neck portion 104b of the
piston 104 is arranged outside of the cylinder bore 102a. A pair of
shoe seats or semi-spherical recesses 104c is inwardly recessed to
define pockets in the neck portion 104b of the piston 104. A pair
of shoes 105 is arranged in the neck portion 104b of the piston
104, and received by the shoe seats 104c. The peripheral portions
of the swash plate 103 are slidably sandwiched between the shoes
105. The rotational movement of the swash plate 103 accompanying
with the rotation of the drive shaft 101 is converted to the
reciprocating movement of the piston 104 through the shoes 105.
Then the compression cycle is performed such that a refrigerant gas
is sucked into the cylinder bore 102a, compressed and discharged
out.
[0004] A piston 104 is provided with a rotation preventing portion
106. The piston 104 and the rotation preventing portion 106 are
formed integrally. The rotation preventing portions 106 are formed
on the neck portion 104b of the piston 104 so as to protrude ahead
and behind in the rotational direction of the swash plate 103,
respectively. The rotation preventing portions 106 are formed such
that the curvature of contacting surfaces 106a confronting a
contacting portion 102b of the housing 102 is smaller than that of
the head portion 104a. An axis of an arc of the rotation preventing
portion 106 is different from that of an arc of the head portion
104a. The housing 102 and the piston 104 are made of aluminium or
an aluminium alloy for reducing its weight. A coating layer is
formed on the head portion 104a and the contacting surface 106a for
preventing seizure between the housing 102 and the piston 104 and
for improving wearproof of the piston 104. The contacting portion
102b prevents the rotation of the piston, cooperating with the
rotation preventing portion 106.
[0005] The connecting structure between the piston 104 and the
swash plate 103 through the shoes 105 allows the rotation around
the axis S of the piston 104. If the piston 104 rotates
significantly, the neck portion interferes with the rotating swash
plate 103 and there is a possibility of causing vibration and
noise. However, as shown in FIG. 8(a) as two dotted chain line, the
amount of rotation of the piston 104 could be reduced by that one
end of the rotation preventing portion 106 contacts with the
contacting portion 102b. Therefore, the piston 104 does not
interfere with the swash plate 103.
[0006] On the other hand, another type of compressor, in which the
rotation preventing member and the piston are arranged separately,
is disclosed in Japanese Unexamined Patent Publication No.
9-105377.
[0007] As shown in FIG. 8(b) and FIG. 9, a protruding portion 111
is formed on the end portion of the piston 110. The intermediate
portion of an arched leaf spring 112 is fastened to the protruding
portion 111 with a screw 113. As shown in FIG. 8(b), the leaf
spring 112 is assembled such that both end portions 112a are
pressed to the inner wall surface 114a of the cylinder block
(housing) 114, slidably in the moving direction of the piston 110,
respectively.
[0008] Generally, a piston is produced by performing machining
process, coating process to form a coating layer to cover the
surface, and polishing process etc. to the material formed by
molding or forging. As the piston 104 disclosed in Japanese
Unexamined Patent publication No. 11-201037, it becomes troublesome
to machine the piston or form a coating layer on the piston by roll
coating, for the rotation preventing portion 106 and the piston 104
are formed integrally and the axis of the arc of the rotation
preventing portion 106 deviates from that of the arc of the
contacting surface 106a.
[0009] On the other hand, a compressor disclosed in Japanese
Unexamined Patent Publication No. 9-105377 has the following
problems.
[0010] (1) The rotation prevention of the piston 110 is performed
by the leaf spring 112 which is continually press-contacted to the
inner wall surface 114a of the housing 114, and an unbalanced load
is continually affected to a piston 110 from the leaf spring 112.
Therefore, the inner wall surface 114a of the housing 114 to which
the leaf spring 112 is press-contacted, is easily worn, and then
the piston 110 is easily worn partially. To control the amount of
rotation of the piston 110 under a required quantity, it needs to
strengthen the spring force of the leaf spring 112. However, that
makes the above problem remarkable.
[0011] (2) The protruding portion 111 is formed on the end portion
of the piston 110 and the leaf spring 112 is fastened to it with
the screw 113. Such a structure axially lengthen the piston 110 and
increases the size of the compressor. Furthermore, it needs to
machine the screw 113 and a tapped hole 115, and increases the
manufacturing process.
SUMMARY OF THE INVENTION
[0012] The present invention was achieved by recognizing the above
problems in the prior art. The purpose is to propose a compressor
in which the rotation of the piston is prevented without affecting
a big unbalanced load to the piston and the manufacture for the
piston is simplified.
[0013] A piston type compressor comprises a housing having a
cylinder bore therein, a drive shaft rotatably supported in the
housing, a cam plate coupled on the drive shaft to rotate
integrally therewith, a piston being operatively connected to the
cam plate through a pair of shoes, the piston including a head
portion and a neck portion, the head portion of the piston being
inserted into the cylinder bore, and the cam plate converting
rotation of the drive shaft to reciprocating movement of the piston
through the pair of shoes. In the above compressor, the present
invention has the following features. A rotation preventing member
is formed separately from the piston and mounted on the piston. A
contacting portion is formed in the housing. The rotation
preventing member prevents rotation around the axis of the piston,
by contacting with the contacting portion when the piston rotates
by a certain angle.
[0014] According to the present invention, it is easy to machine
the piston and to form a coating layer on the piston by roll
coating etc., for the rotation preventing member is formed
separately from the piston. During the running of the compressor, a
moment around the axis of the piston acts to the piston,
accompanied with the rotation of the swash plate, and the piston
tends to rotate around the axis. However, when the piston rotates
by a certain angle from the base portion, the rotation is
prevented, for the rotation preventing member contacts the
contacting portion. Therefore, the piston slides without receiving
an unbalanced load, different from the structure that a leaf spring
is used as the rotation preventing member.
[0015] Furthermore, the present invention has a following feature.
The rotation preventing member is received in the piston. A stopper
for preventing the relative movement of the rotation preventing
member in the axial direction of the piston is arranged between the
rotation preventing member and the piston. Accordingly, even after
long use, the rotation preventing member is not separated from the
piston by slipping in the axial direction of it.
[0016] Furthermore, the present invention has a following feature.
The rotation preventing member is provided with a rotation
preventing portion to prevent the rotation in both directions
around the axis of the piston. Accordingly, one rotation preventing
member can prevent the piston from rotating in both directions.
[0017] Furthermore, the present invention has a following feature.
The above rotation preventing member is made of a different
material from that of the housing. Accordingly, it does not need to
form a coating on the rotation preventing member for avoiding the
seizure, and then it is manufactured easily.
BRIEF DESCRIPTION OF THE DRAWINGS
[0018] The features of the present invention that are believed to
be novel are set forth with particularity in the appended claims.
The invention together with objects and advantages thereof, may
best be understood by reference to the following description of the
presently preferred embodiments together with the accompanying
drawings in which:
[0019] FIG. 1 is a cross-sectional view illustrating a compressor
according to a first embodiment of the present invention;
[0020] FIG. 2(a) is a perspective, exploded view illustrating a
piston and a rotation preventing member according to the first
embodiment of the present invention;
[0021] FIG. 2(b) is a perspective view illustrating the piston
provided with the rotation preventing member according to FIG.
2(a);
[0022] FIG. 3 is a schematic view illustrating the rotation
preventing operation of the piston according to the first
embodiment of the present invention;
[0023] FIG. 4 is a perspective, exploded view illustrating the
piston and the rotation preventing member according to a second
embodiment of the present invention;
[0024] FIG. 4(a) is a rear elevation view illustrating the rotation
preventing member according to FIG. 4;
[0025] FIG. 5(a) and FIG. 5(b) are rear elevation views
illustrating the pistons provided with the rotation preventing
member according to a third and a fourth embodiments of the present
invention, respectively;
[0026] FIG. 6(a) and FIG. 6(b) are partial cross-sectional views
illustrating compressors according to a fifth and a sixth
embodiments of the present invention, respectively;
[0027] FIG. 7 is a partial cross-sectional view illustrating a
prior art compressor;
[0028] FIGS. 8(a) and 8(b) are schematic views illustrating the
rotation preventing operation of a first and a second prior art
pistons, respectively; and
[0029] FIG. 9 is a perspective view illustrating the piston
according to FIG. 8(b).
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0030] Referring to FIG. 1 to FIG. 3, an embodiment according to
the present invention will now be described.
[0031] As shown in FIG. 1, a variable displacement compressor of a
single-headed piston type is illustrated. A front housing 11 is
secured to the front end of a cylinder block 12 as a center
housing. A rear housing 13 is secured to the rear end of the
cylinder block 12 through a valve plate assembly 14. Both the
housings 11, 13 and the cylinder block 12 are made of metallic
material such as aluminium or an aluminium alloy.
[0032] A crank chamber 15 is defined by the front housing 11 and
the cylinder block 12. A drive shaft 16 is rotatably supported
between the front housing 11 and the cylinder block 12 so as to be
inserted into the crank chamber 15. The drive shaft 16 is
operatively connected to an engine of a vehicle as an external
driving source (which is not illustrated), through a clutch
mechanism such as an electromagnetic clutch. Accordingly, when the
vehicle engine is operated, the drive shaft 16 is driven by the
connection of the electromagnetic clutch.
[0033] A rotary support member 17 is mounted on the drive shaft 16
in the crank chamber 15. A swash plate 18 as a cam plate is
supported inclinably on the drive shaft 16. A hinge mechanism 19 is
located between the rotary support member 17 and the swash plate
18. The swash plate 18 is inclinable to the drive shaft 16 and
rotatable integrally with the drive shaft 16 by the hinge
connection through the hinge mechanism 19 to the rotary support
member 17.
[0034] A plurality of (only one cylinder bore is illustrated in the
drawings) cylinder bores 12a are formed to penetrate the cylinder
block 12, around the axis L of the drive shaft 16. A plurality of
single-headed pistons 20 are accommodated in the respective
cylinder bores 12a. Especially each head portion 22 thereof is
accommodated in each cylinder bore 12a, respectively. Each piston
20 is engaged with the swash plate 18 through each pair of shoes
21. Accordingly, the rotational movement of the drive shaft 16 is
converted to the reciprocating movement of each piston 20 in each
cylinder bore 12a through the swash plate 18 and each pair of shoes
21.
[0035] A suction chamber 27 and a discharge chamber 28 are defined
in the rear housing 13. A suction port 29, a suction valve 30, a
discharge port 31 and a discharge valve 32 are formed in the valve
plate assembly 14. A refrigerant gas in the suction chamber 27 is
sucked into the cylinder bore 12a through the suction port 29 and
the suction valve 30 by the suction stroke of the piston 20. The
refrigerant gas sucked into the cylinder bore 12a is compressed
until a certain pressure by the compression stroke of the piston
20, and then it is discharged to the discharge chamber 28 through
the discharge port 31 and the discharge valve 32.
[0036] A supply passage 33 communicates the discharge chamber 28
with the crank chamber 15. A bleeding passage 34 communicates the
crank chamber 15 with the suction chamber 27. A displacement
control valve 35 is interposed in the supply passage 33. A pressure
sensing passage 36 communicates the suction chamber 27 with the
displacement control valve 35.
[0037] A diaphragm 35a of the displacement control valve 35 senses
the suction pressure introduced through the pressure sensing
passage 36, and the displacement control valve 35 changes the
opening degree of the supply passage 33 by moving the valve body
35b between the opening position and the closing position. When the
opening degree of the supply passage 33 is changed, the amount of
the discharged refrigerant gas introduced into the crank chamber 15
is changed, and the pressure in the crank chamber 15 is changed, in
connection with the amount of the refrigerant gas relieved to the
suction chamber 27 through the bleeding passage 34. Therefore, the
difference between the pressure in the crank chamber 15 and the
pressure in the cylinder bore 12a through the piston 20 is changed,
and the inclination angle of the swash plate 18 is changed
accordingly. As the result, the stroke of the piston 20 is changed,
and the discharge capacity is adjusted accordingly.
[0038] Next, the construction of the piston 20 is described in
detail.
[0039] As shown in FIG. 1 to FIG. 3, the piston 20 is composed of a
head portion 22, which is cylindrical and inserted into the
cylinder bore 12a, and a neck portion 23, which is arranged outside
of the cylinder bore 12a. Those are made of metallic material such
as aluminium or an aluminium alloy, and formed integrally. Shoe
seats 23a are inwardly recessed to define pockets in the neck
portion 23. A pair of shoes 21 is arranged in the neck portion 23
and its concave spherical portion is received by the shoe seats
23a. The swash plate 18 is slidably sandwiched by the shoes 21 at
the front and the rear surfaces of its outer periphery. Though it
is not shown, a resin coating layer for improving wearproof of the
piston 20 is formed on the head portion 22.
[0040] A rotation preventing member 24 is mounted on a covered
surface 23e which is formed at the rearward of the neck portion 23
of each piston 20. The covered surface 23e is formed as a part of a
circumferential surface which has a same radius of curvature and a
same axis as an outer circumferential surface 22a of the head
portion 22. The covered surface 23e is machined at the same time as
the outer circumferential surface 22a.
[0041] The rotation preventing member 24 is composed of a pair of
rotation preventing portions 24A, an abutting portion 24B and a
pair of caulking portions 24C to mount to the neck portion 23.
Those are made of metallic material such as iron series and formed
integrally. FIG. 2(a) is a perspective, exploded view illustrating
the piston 20 and the rotation preventing member 24 which shows the
state that a pair of caulking portions 24C are not yet caulked. The
rotation preventing portions 24A are formed ahead of and behind in
the rotational direction of the swash plate 18, sandwiching the
abutting portion 24B. A contacting surface 24a as an arc surface is
formed in the outer circumferential side of the rotation preventing
portion 24A. An abutting surface 24b as an arc surface is formed in
the outer circumferential side of the abutting portion 24B. The
contacting surfaces 24a are connected through the abutting surface
24b. Both the contacting surfaces 24a and the abutting surface 24b
are on the same arc surface. The radius of a curvature of the
contacting surface 24a and the abutting surface 24b is larger than
that of the outer circumferential surface 22a of the head portion
22, and is smaller than that of the inner wall surface of the front
housing 11. The rotation preventing member 24 is mounted to the
piston 20 by a pair of caulking portions 24C in a state that the
rotation preventing member 24 is elastically deformed.
[0042] The piston 20 is arranged so that the abutting surface 24b
and the contacting surface 24a face toward the inner wall surface
of the front housing 11. The inner wall surface of the front
housing 11 constitutes the contacting portion 11a. There is a
clearance between the abutting surface 24b and the contacting
portion 11a, and the contacting surface 24a and the contacting
portion 11a when the rotation preventing member 24 is at the base
position, as shown in FIG. 3 as a solid line. The contacting
portion 11a prevents the rotation of the piston 20, cooperating
with the rotation preventing portion 24A.
[0043] As shown in FIG. 3, the above described connecting structure
between the piston 20 and the swash plate 18 through the shoes 21
allows the rotation of the piston 20 around the axis S thereof.
Therefore, the piston 20 tends to rotate around its axis S when it
receives any force. Especially, the shoes 21 tend to rotate to the
same direction as the rotating direction of the swash plate 18 by
the sliding connection therebetween. Accordingly, the piston 20
tends to rotate to the same direction as the rotating direction of
the swash plate 18 (e.g. clockwise direction in FIG. 3) by the
turning force of the swash plate 18 through the shoes 21.
[0044] However, as shown in FIG. 3, as two dotted chain lines, the
abutment between the contacting surface 24a behind in the
rotational direction and the contacting portion 11a prevents the
rotation of the piston 20 to the same direction as the rotation of
the swash plate 18, and the abutment between the contacting surface
24a ahead in the rotational direction and the contacting portion
11a prevents the rotation of the piston 20 to the opposite
direction to the rotation of the swash plate 18 (counterclockwise
direction in FIG. 3). As mentioned above, the rotation of the
piston 20 is reduced, so that the neck portion 23 of the piston 20
does not interfere with the swash plate 18. Therefore, the
occurrence of vibration or noise due to the interference of the
piston 20 with the swash plate 18 is prevented.
[0045] The above embodiment has the following effects.
[0046] (1) As the rotation preventing member 24 is formed
separately from the piston 20, it is easy to machine the piston 20
and to form a coating layer on it by a roll coating method etc.
[0047] (2) The rotation preventing portion 24A and the contacting
portion 11a of the housing 11 contact each other when the piston 20
rotates by a certain angle from the base position. Therefore, the
piston 20 normally slides without receiving an unbalanced load, and
the piston 20 is not worn partially, accordingly.
[0048] (3) As the rotation preventing member 24 is made of
different materials from those of the housing 11, it does not need
to take any measures such as coating to avoid the seizure.
[0049] (4) As the covered surface 23e is a circumferential surface
which has the same radius of curvature and the same axis as the
outer circumferential surface 22a, it is easy to machine the piston
20 and to form a coating layer on the piston 20 by a roll coating
method etc.
[0050] Embodiments are not limited to the above, but the followings
also may be applied.
[0051] (1) The rotation preventing member may be made of metallic
material except iron.
[0052] (2) The rotation preventing member 24 is made of metallic
material such as aluminium series. And a coating layer such as
resin coating and tin plate is formed on it for avoiding the
seizure.
[0053] (3) The rotation preventing member 24 is engaged with the
piston 20, and the relative movement of the rotation preventing
member 24 in the axial direction of the piston 20 is prevented by a
stopper. As shown in FIGS. 4 and 4(a), a protruding portion 24D on
the rotation preventing member 24 and a concave portion 23b on the
piston 20 compose a stopper. The rotation preventing member 24 is
mounted on the piston 20 by fitting the protruding portion 24D to
the concave portion 23b, and the rotation preventing member 24 is
restricted its relative movement in the axial direction of the
piston 20, accordingly.
[0054] (4) A coating layer for wear resistance may be formed on the
rotation preventing member 24.
[0055] (5) The rotation preventing member 24 may be made of
thermosetting resin.
[0056] (6) The rotation preventing member 24 may be mounted to the
piston 20 by shrinkage fit.
[0057] (7) As shown in FIG. 5(a), the rotation preventing member 24
may be mounted to the piston 20 by adhesion.
[0058] (8) As shown in FIG. 5(b), a pair of rotation preventing
portions 24A does not necessarily connect each other through the
abutting portion 24B and may be composed separately.
[0059] (9) The rotation preventing member 24 is not necessarily
mounted fixedly to the piston 20. As shown in FIG. 6(a), a
protruding portion 24E formed on the rotation preventing member 24
may be mounted on the piston 20 by inserting it loosely into a
concave portion 23c on the neck portion 23 of the piston 20 to
function as a stopper. On the contrary, a protruding portion may be
formed on the neck portion 23, and a concave portion may be formed
on the rotation preventing member 24. Such composition makes it
easy to assemble the rotation preventing member 24 into the piston
20.
[0060] (10) As shown in FIG. 6(b), the rotation preventing member
24 may be assembled into the piston 20 by inserting it loosely into
the concave portion 23d formed on the neck portion 23 composing a
stopper. Of course, the rotation preventing member 24 may be
engaged with the neck portion 23.
[0061] (11) The invention may be embodied in the fixed displacement
compressor.
[0062] (12) A pair of contacting surfaces 24a and the abutting
surface 24b are not necessarily on the same arc. The contacting
surfaces 24a and the abutting surface 24b, of which the centers of
the arc are different, compose the contacting surface 24a and the
abutting surface 24b.
[0063] (13) The contacting surface 24a may be formed in a plane
surface.
[0064] (14) The abutting surface 24b may be formed in a plane
surface.
[0065] (15) The compressor is not limited to a single-headed piston
type, but also applied to a double-headed piston type.
[0066] (16) The compressor may be driven by a motor.
[0067] As mentioned above, according to the present invention, the
rotation of the piston may be effectively prevented, and also the
piston is manufactured easily.
[0068] Therefore the present examples and embodiments are to be
considered as illustrative and not restrictive and the invention is
not to be limited to the details given herein but may be modified
within the scope of the appended claims. +
* * * * *