BACKGROUND OF THE INVENTION
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The present invention relates to a variable displacement piston type
compressor for use in a vehicle air conditioner.
-
Unexamined Japanese Patent Publication No. 9-203377 discloses a
variable displacement compressor of such type. FIG. 14 illustrates a partially
longitudinal cross-sectional view of a variable displacement compressor
according to a prior art. A housing 101 of the compressor defines a cylinder bore
101 a that accommodates a piston 102. A drive shaft 103 is rotatably supported by
the housing 101. A rotor 104 is connected to the drive shaft 103 so as to rotate
integrally therewith. A swash plate 105 is supported by the drive shaft 103 so that
it slides and inclines relative to the drive shaft 103.The piston 102 engages the
periphery of the swash plate 105 through a pair of shoes 107. A hinge mechanism
108 is interposed between the rotor 104 and the swash plate 105.
-
Accordingly, the rotation of the drive shaft 103 is converted to the
reciprocation of the piston 102 through the rotor 104, the hinge mechanism 108
and the swash plate 105, while the swash plate 105 is guided by the hinge
mechanism 108 to slide on the drive shaft 103 in accordance with the inclination
of the swash plate 105. Thus, the displacement volume of the compressor is
varied.
-
The hinge mechanism 108 includes a pair of first protrusions 108a (only
one is shown in FIG. 14), a second protrusion 108b and a cam surface 108c. The
first protrusions 108a extend from the rotor 104 toward the swash plate 105. The
second protrusion 108b extends from the swash plate 105 toward the rotor 104.
The distal end of the second protrusion 108b is inserted between the first
protrusions 108a. The cam surface 108c is formed at the proximal portion of the
first protrusions 108a. The first protrusions 108a and the second protrusion 108b
contact with a certain amount of area to engage each other so that the rotation of
the rotor 104 is transmitted to the swash plate 105 through the hinge mechanism
108. The distal end of the second protrusion 108b slidably contacts the cam
surface 108c so that axial load that acts on the swash plate 105 due to
compression reactive force is received by the cam surface 108c through the
second protrusion 108b.
-
In the hinge mechanism 108, the first protrusions 108a and the second
protrusion 108b are integrally formed with the rotor 104 and the swash plate 105,
respectively. An unwanted feature is that as the swash plate 105 inclines to twist
the second protrusion 108b by the pair of first protrusions 108b due to offset axial
load based upon the compression reactive force, sliding resistances increase
between the side surfaces of the first protrusions 108a and the second protrusion
108b and between the distal end of the second protrusion 108b and the cam
surface 108c due to the contact of the edge. This leads to early abrasion of each
sliding surface. In other words, durability of the hinge mechanism 108 is
deteriorated, and unsmooth operation of the hinge mechanism 108 leads to
deteriorated controllability for the displacement volume of the compressor.
Therefore, there is a need for a variable displacement compressor that improves
durability of a hinge mechanism and that ensures smooth operation of the hinge
mechanism.
SUMMARY OF THE INVENTION
-
In accordance with the present invention, a variable displacement
compressor has a housing, a piston, a drive shaft, a rotor, a cam plate and a
hinge mechanism. The housing defines a cylinder bore. The piston is
accommodated in the cylinder bore. The drive shaft is rotatably supported by the
housing. The rotor is connected to the drive shaft so as to rotate integrally with.
The cam plate is supported by the drive shaft so as to slide and incline relative to
the drive shaft and is operatively connected to the piston. The hinge mechanism
is interposed between the rotor and the cam plate and guides the cam plate to
incline and slide relative to the drive shaft. Thus, the displacement volume of the
compressor is varied. The rotation of the drive shaft is converted to the
reciprocation of the piston through the rotor, the hinge mechanism and the cam
plate. The hinge mechanism includes a first hinge element and a second hinge
element. The first hinge element is provided on the rotor. The second hinge
element is provided on the cam plate and is engaged with the first hinge element.
At least one of the first and second hinge elements has a degree of freedom for
motion against the rotor and/or the cam plate to which the hinge element having
the degree of freedom for motion belongs.
-
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.
BRIEF DESCRIPTION OF THE DRAWINGS
-
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:
- FIG. 1 is a longitudinal cross-sectional view of a variable displacement
compressor according to a first preferred embodiment of the present invention;
- FIG. 2 is a side view of a hinge mechanism according to the first preferred
embodiment of the present invention;
- FIG. 3 is a plan view of the hinge mechanism according to the first
preferred embodiment of the present invention;
- FIG. 4 is a hinge element of a swash plate according to the first preferred
embodiment of the present invention;
- FIG. 5 is an enlarged longitudinal cross-sectional view of a hinge
mechanism according to a second preferred embodiment of the present
invention;
- FIG. 6 is a plan view of a hinge mechanism according to a third preferred
embodiment of the present invention;
- FIG. 7 is an enlarged side view of a hinge mechanism according to a
fourth preferred embodiment of the present invention;
- FIG. 8 is an enlarged longitudinal cross-sectional view of a hinge
mechanism according to a fifth preferred embodiment of the present invention;
- FIG. 9 is a plan view of a hinge mechanism according to a sixth preferred
embodiment of the present invention;
- FIG. 10 is an enlarged longitudinal cross-sectional view of a hinge
mechanism according to a seventh preferred embodiment of the present
invention;
- FIG. 11 is an enlarged perspective view of the hinge mechanism
according to the seventh preferred embodiment of the present invention;
- FIG. 12 is a longitudinal cross-sectional view of a hinge mechanism
according to an eighth preferred embodiment of the present invention;
- FIG. 13 is a plan view of the hinge mechanism according to the eighth
preferred embodiment of the present invention; and
- FIG. 14 is a partially longitudinal cross-sectional view of a variable
displacement compressor according to a prior art.
-
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
-
A first preferred embodiment of the present invention will now be
described with reference to FIGs. 1 through 4. The present invention is applied to
a variable displacement compressor for a refrigerant circuit of a vehicle air
conditioner in the first preferred embodiment. The left side and the right side
respectively correspond to the front side and the rear side of the compressor in
FIG. 1.
-
FIG. 1 illustrates a longitudinal cross-sectional view of the variable
displacement compressor according to the first preferred embodiment of the
present invention. A housing of the compressor includes a cylinder block 11, a
front housing 12 and a rear housing 14. The front housing 12 is fixedly connected
to the front end of the cylinder block 11. The rear housing 14 is fixedly connected
to the rear end of the cylinder block 11 through a valve plate assembly 13.
-
A crank chamber 15 is defined between the cylinder block 11 and the front
housing 12. A drive shaft 16 is rotatably supported by the housing and extends
through the crank chamber 15 from the front housing 12 to the cylinder block 11.
The drive shaft 16 is rotated by the power transmitted from an engine (not shown)
for traveling a vehicle.
-
In the crank chamber 15, a rotor 17 made of cast iron is fixedly connected
to the drive shaft 16 so as to rotate integrally therewith. The front end surface of
the rotor 17 and the facing inner wall surface of the front housing 12 interpose a
thrust bearing 35. The crank chamber 15 accommodates a swash plate or a cam
plate 18. The swash plate 18 is made of iron series metal, such as iron and iron
alloy. The swash plate 18 is formed by forging.
-
A through hole 20 is formed at the center of the swash plate 18. The drive
shaft 16 extends through the through hole 20. The swash plate 18 is supported by
the drive shaft 16 through an inner surface 20a of the through hole 20 in such a
manner that the swash plate 18 inclines and slides relative to the drive shaft 16. A
circular clip 32 is fitted on the drive shaft 16 on the rear side to the swash plate 18.
A coil spring 33 for increasing inclination angle of the swash plate 18 is arranged
between the circular clip 32 and the swash plate 18 so as to urge the middle
portion of the swash plate 18 forward.
-
A hinge mechanism 19 is interposed between the rotor 17 and the swash
plate 18. The hinge mechanism 19 includes a first hinge element 52 provided on
the rotor 17 and a second hinge element 51 provided on the swash plate 18. The
swash plate 18 is coupled to the rotor 17 through the hinge mechanism 19 and is
supported by the drive shaft 16 through the inner surface 20a of the though hole
20. Accordingly, the swash plate 18 is integrally rotatable with the rotor 17 and the
drive shaft 16, while it is inclinable relative to the drive shaft 16 in accordance with
sliding movement in the direction of the axis L of the drive shaft 16.
-
Incidentally, with respect to the swash plate 18, the inner surface 20a of
the through hole 20 is treated by induction hardening for improving sliding
performance against the drive shaft 16 and for improving abrasion resistance.
-
A plurality of cylinder bores 22 (one of them shown in FIG. 1) extends
through the cylinder block 11 and is arranged around the axis L of the drive shaft
16 at equiangular positions. Each of the cylinder bores 22 accommodates a
single-headed piston 23 so as to be reciprocated therein. The front and rear
openings of each cylinder bore 22 are respectively closed by the top end surface
of the piston 23 and the front end surface of the valve port assembly 13. Thus, a
compression chamber 24 is defined in each of the cylinder bores 22 and varies its
volume in accordance with the reciprocation of the respective piston 23. Each of
the pistons 23 engages the outer periphery of the swash plate 18 through a pair of
semispherical shoes 25. Accordingly, the rotation of the swash plate 18 in
accordance with the rotation of the drive shaft 16 is converted to the reciprocation
of the piston 23 through the shoes 25.
-
Incidentally, with respect to the swash plate 18, sliding surfaces 18b
against the respective shoes 25 are treated by induction hardening for improving
sliding performance against the shoes 25 and for improving abrasion resistance.
-
A suction chamber 26 and a discharge chamber 27 are defined between
the valve plate assembly 13 and the rear housing 14. The refrigerant gas in the
suction chamber 26 is introduced into the compression chamber 24 through a
suction port 28 and a suction valve 29 as each piston 23 moves from its top dead
center to its bottom dead center. The suction port 28 and the suction valve 29 are
formed in the valve plate assembly 13. The refrigerant gas in the compression
chamber 24 is compressed to a predetermined pressure value as the piston 23
moves from the bottom dead center to the top dead center. The compressed
refrigerant gas is discharged to the discharge chamber 27 through a discharge
port 30 and a discharge valve 31, which are formed in the valve plate assembly
13.
-
The compressor optionally varies its displacement volume and regulates
its displacement volume in such a manner that a control valve 21 adjusts pressure
in the crank chamber 15. In other words, pressure differential between the crank
chamber 15 and the compression chambers 24 is varied by the control valve 21 in
response to variation of the pressure in the crank chamber 15. As a result, the
inclination angle of the swash plate 18 is varied, and the stroke of the piston 23 is
adjusted.
-
As the pressure in the crank chamber 15 decreases, the swash plate 18 is
pushed by the coil spring 33 to increase its inclination angle. Thus, the strokes of
the pistons 23 increase, and the displacement volume of the compressor
increases. The front end surface of the swash plate 18 has a portion 18a for
regulating maximum inclination angle. The portion 18a also serves as a balance
weight. The maximum inclination angle of the swash plate 18 is regulated in such
a manner that the portion 18a contacts the rear end surface of the rotor 17, as
shown in FIG. 1.
-
On the other hand, as the pressure in the crank chamber 15 increases,
the swash plate 18 resists against the coil spring 33 to decrease its inclination
angle. Thus, the strokes of the pistons 23 decrease, and the displacement volume
of the compressor decreases. The minimum inclination angle of the swash plate
18 is regulated by the circular clip 32 and the coil spring 33.
-
FIG. 2 illustrates a side view of the hinge mechanism 19 according to the
first preferred embodiment of the present invention. FIG. 3 illustrates a plan view
of the hinge mechanism 19 according to the first preferred embodiment of the
present invention. Now referring to FIGs. 1 through 3, an engaging recess 41 is
formed at the rear end of the rotor 17 and faces a point TDC of the swash plate 18.
The point TDC is a center of the hypothetical spherical surface of the shoes 25
when the piston 23 is positioned at a top dead center. The engaging recess 41 is
defined by a pair of first protrusions 43 that extend toward the swash plate 18.
The first protrusions 43 are respectively disposed at the rear end on a preceding
side and on a following side in the rotational direction of the rotor 17.
-
A pair of second protrusions 44 extends toward the rotor 17 and is
arranged at the front end of the swash plate 18 so as to face the engaging recess
41. The second protrusions 44 are respectively disposed on a preceding side and
on a following side in the rotational direction of the drive shaft 16 so as to
interpose a hypothetical plane including the axis L and the point TDC. Each of the
distal ends of the second protrusions 44 fits into the engaging recess 41. Each of
the second protrusions 44 includes a side surface 44a that faces away from each
other. Each of the side surfaces 44a contacts a side surface 43a of the first
protrusion 43 with a certain amount of area. The side surfaces 43a partially form
the inner surface of the engaging recess 41. Accordingly, the rotational power of
the rotor 17 is transmitted to the swash plate 18 through one of the first
protrusions 43 (the side surfaces 43a) and one of the second protrusions 44 (the
side surfaces 44a).
-
Incidentally, to improve general-purpose property, with respect to the
compressor of the first preferred embodiment, the hinge mechanism 19 is
symmetrically formed relative to the the hypothetical plane including TDC and the
axis L along the rotational direction of the drive shaft 16 so as to appropriately
respond either rotational direction of the drive shaft 16, even if a mounted engine
rotates in either direction.
-
A cam portion 45 for receiving axial load is formed on the proximal portion
of each first protrusion 43 in the engaging recess 41. The cam portions 45 and the
first protrusions 43 constitute the first hinge element 52 on the side of the rotor 17.
The rear end surface of each cam portion 45 facing the swash plate 18 forms a
cam surface 45a that protrudes toward the rear side as it approaches the drive
shaft 16. Each of the second protrusions 44 forms a convex circular arc surface
44b and slidably contacts the cam surface 45a of the corresponding cam portion
45 by the circular arc surface 44b. Accordingly, the axial load that acts on the
swash plate 18 due to the compression reactive force is received by the cam
surfaces 45a of the cam portions 45 through the circular arc surfaces 44b of the
second protrusions 44, respectively.
-
With respect to the prior art shown in FIG. 14, the hinge mechanism 108
includes the single and relatively large-scaled second protrusion 108b. However,
in the first preferred embodiment, the second protrusion 108b of the prior art is
divided into the two second protrusions 44. The above structure ensures the
same width for receiving axial load as that of the second protrusion 108b of the
prior art and lightens the swash plate assembly 18, 51 by changing the structure
of the second protrusion 108b of the prior art to a hollow structure.
-
As the compressor increases its displacement volume, the distal ends of
the second protrusions 44 rotate around a central axis S of the circular arc
surfaces 44b in the clockwise direction in FIG. 1, while they move on the cam
surfaces 45a of the respective cam portions 45 away from the drive shaft 16.
Thus, the hinge mechanism 19 guides to increase the inclination angle of the
swash plate 18. On the contrary, when the compressor reduces its displacement
volume, the distal ends of the second protrusions 44 rotate around the central
axis S of the circular arc surfaces 44b in the counterclockwise direction in FIG. 1,
while they move on the cam surfaces 45a of the cam portions 45 to approach the
drive shaft 16. Thus, the hinge mechanism 19 guides to reduce the inclination
angle of the swash plate 18.
-
Incidentally, the first hinge element 52 and the second hinge element 51
slide on each other at sliding surfaces, such as the side surfaces 43a, 44a of the
respective first and second protrusions 43, 44, the circular arc surfaces 44b of the
respective second protrusions 44, and the cam surfaces 45a of the respective
cam portions 45. The above sliding surfaces are treated by induction hardening
for improving their sliding performance and abrasion resistance.
-
In the second hinge element 51, the induction hardening may exclusively
be treated at a portion including the side surfaces 44a and the circular arc
surfaces 44b or may entirely be treated. Particularly, the former treatment
restrains the distortion and crack of the second hinge element 51 of the swash
plate 18 due to heat affection of the hardening. Incidentally, the induction
hardening may be treated only at portions including the side surfaces 43a and the
cam surfaces 45a or may be treated at the entire first hinge element 52.
Particularly, the former treatment restrains the distortion and crack of the first
hinge element 52 due to heat affection of the hardening.
-
As shown in FIGs. 1 through 3, the second hinge element 51 is separately
formed from the swash plate 18. The second hinge element 51 includes a base
plate or a base 47 and a pair of second protrusions 44 that extend from the front
end surface of the base plate 47. The swash plate 18 is made of iron series metal
and is formed by forging. On the other hand, the second hinge element 51 is
made of aluminum series metal, such as aluminum and aluminum alloy. That is,
the second hinge element 51 is made of different material from that of the swash
plate 18, and the second protrusions 44 and the base plate 47 are integrally
formed by forging or by molding. With respect to the swash plate 18, the sliding
surfaces 18b against the shoes 25 and the inner surface 20a of the through hole
20 are polished and treated by induction hardening before the second hinge
element 51 is assembled to the swash plate 18.
-
In the second hinge element 51, a shaft 48 is integrally formed at the
center of the rear end surface of the base plate 47 and extends vertically relative
to the base plate 47. In the swash plate 18, a shaft hole 18c is recessed inwardly
from the sliding surfaces 18b against the shoes 25 and extends in thickness of the
swash plate 18. The second hinge element 51 is loosely fitted into the shaft hole
18c of the swash plate 18 by the shaft 48.
-
Accordingly, referring to FIG. 4, the diagram illustrates the second hinge
element 51 according to the first preferred embodiment of the present invention.
The second hinge element 51 is rotatable on the swash plate 18 relative to an
axis M of the shaft 48 (or the shaft hole 18c). Namely, the second hinge element
51 has the degree of freedom for rotation against the swash plate 18 to which the
second hinge element 51 belongs. The rotation of the second hinge element 51 is
regulated in a predetermined angular range in such a manner that an end surface
47a of the base plate 47 near the drive shaft 16 contacts the wall surface of a step
or a regulating means 18d formed on the front end surface of the swash plate 18.
-
Incidentally, referring back to FIGs. 1 and 2, a lightening recess 48a is
formed at the distal end of the shaft 48 on the side near the drive shaft 16 so that
the swash plate 18 avoids interfering with the coil spring 33 when positioned at
the maximum inclination angle.
-
The following advantageous effects are obtained from the first preferred
embodiment.
- (1) The second hinge element 51 has the degree of freedom for motion
against the swash plate 18. Accordingly, even if offset axial load due to the
compression reactive force acts on the inclined swash plate 18 to twist the second
protrusions 44 in the engaging recess 41, stress due to the inclined swash plate
18 moves the second hinge element 51 so that the second protrusions 44 avoid
twisting in the engaging recess 41. As a result, the side surfaces 44a of the
respective second protrusions 44 and the side surfaces 43a of the respective first
protrusions 43 contact each other with a certain amount of area, while the circular
arc surfaces 44b of the respective second protrusions 44 and the cam surfaces
45a of the respective cam portions 45 contact each other with a line. Thus, no
edge abuts at each sliding surface. Accordingly, the hinge mechanism 19
smoothly moves, and the displacement volume of the compressor smoothly
varies.
- (2) The second hinge element 51 on the swash plate 18 has the degree of
freedom for rotation. In comparison to a hinge mechanism that has a degree of
freedom for sliding, the second hinge element 51 effectively avoids the second
protrusions 44 from twisting in the engaging recess 41.
- (3) The rotation of the second hinge element 51 is regulated in a
predetermined angular range in such a manner that the second hinge element 51
contacts the step 18d formed on the swash plate 18. Accordingly, the second
hinge element 51 is prevented from excessively rotating on the swash plate 18 so
that noise due to collision between the second protrusions 44 and the first
protrusions 43 is reduced. The structure for regulating the rotation of the second
hinge element 51 helps to assemble the swash plate assembly 18, 51 to the
compressor, that is, the structure helps to easily insert the second protrusions 44
into the engaging recess 41. Namely, for example, without the structure for
regulating the rotation of the second hinge element 51, the rotation of the second
hinge element 51 must be temporarily regulated to fit the second protrusions 44
into the engaging recess 41. Accordingly, a jig for regulating the rotation of the
second hinge element 51 is required so that assembling becomes complicated.
- (4) Since the second hinge element 51 has the degree of freedom for motion
against the swash plate 18, that is, since the second hinge element 51 is
separately formed from the swash plate 18, the shape of the swash plate 18
becomes simple. Accordingly, the swash plate 18 employs forging as a
manufacturing procedure because forging provides better yield and easy
after-machining in comparison to molding. Even if the second hinge element 51
needs to be separately formed and assembled to the swash plate 18, costs are
reduced for manufacturing the compressor. Incidentally, the swash plate 18
formed by forging has relatively high hardenability in comparison to the one
formed by molding.
The separately formed swash plate 18 and the second hinge element 51
permit appropriate selection for their respective material. Accordingly, in the first
preferred embodiment, the swash plate 18 is made of iron series metal that has
relatively high relative density for ensuring its strength and for ensuring moment
for stable variation of the displacement volume. Additionally, the second hinge
element 51 that is arranged at an offset position on the swash plate 18 is made of
aluminum series metal that has relatively low relative density for balancing around
the axis L of the swash plate assembly 18, 51. The second hinge element 51
made of light aluminum series metal helps the balance weight 18a for balancing
around the axis L of the second hinge element 51 to be compact. This leads to the
lightened swash plate assembly 18, 51 and to the lightened compressor.Furthermore, the second hinge element 51 made of aluminum series
metal that is different from that of the first hinge element 52 made of cast iron
effectively prevents a same-metal phenomenon due to slide between the first
hinge elements 52. The same-metal phenomenon means that mutually same
metals lead to inconveniences such as an increase in coefficient of friction.
- (5) In the first and second hinge elements 51, 52 for the hinge mechanism 19,
the second hinge element 51 is separately formed from the swash plate 18.
Accordingly, a depth for fitting the shaft 48 into the shaft hole 18c may be
relatively long in the direction of the axis M so that the swash plate 18 supports
the second hinge element 51 in stable. As a result, for example, the second hinge
element 51 may be rotated in stable relative to the swash plate 18 so as to avoid
twisting of the second protrusions 44 in the engaging recess 41. This leads to
smooth operation of the hinge mechanism 19 and to smooth variation of the
displacement volume of the compressor.
Namely, for example, according to a second preferred embodiment of FIG.
5 which will be described later, when the first hinge element 52 is separately
formed from the rotor 17, the distal end of the shaft 55 needs consideration for not
protruding the distal end of the shaft 55 from the shaft hole 17a including
dimensional tolerance so as to avoid interference between the shaft 55 and the
thrust bearing 35 (See FIG. 1) that is arranged on the front end surface of the rotor
17. Accordingly, the depth for fitting between the shaft 55 and the shaft hole 17a
tends to become small in the direction of the axis M so that the rotor 17 supports
the first hinge element 52 in unstable.
- (6) When the swash plate 18 is separately formed from the second hinge
element 51, the second hinge element 51 does not interfere with the approach of
a grind stone to the sliding surface 18b in a polishing process of the sliding
surfaces 18b that slide on the shoes 25 before the second hinge element 51 is
assembled to the swash plate 18. Therefore, workability of the swash plate 18
becomes better. In other words, the second hinge element 51 does not need to
consider the interference when the sliding surfaces 18b are polished and permits
free determination of its shape and also permits ideal shape for transmitting
power and for guiding inclination of the swash plate 18.
- (7) The second hinge element 51 includes a pair of the second protrusions 44
that are integrated with each other and is rotatable on the swash plate 18. In
comparison to a plurality of the second protrusions 44 that are individually
rotatable on the swash plate 18, the structure of the second hinge element 51 for
rotation, that Is, the structure for increasing the degree of freedom, may be simple
in the first preferred embodiment. Additionally, a plurality of the integrated second
protrusions 44 leads to easy setting in high accuracy the width between the side
surfaces 44a of the respective second protrusions 44. The width largely affects
the smooth operation of the hinge mechanism 19.
- (8) The swash plate 18 that is separately formed from the second hinge
element 51 is treated by hardening at sliding surfaces 18b against the shoes 25
and the inner surface 20a of the through hole 20 that slides on the drive shaft 16
before the second hinge element 51 is assembled to the swash plate 18.
Accordingly, the second hinge element 51 does not receive heat affection due to
hardening and avoids distortion due to the heat affection. No modification for
distortion of the second hinge element 51 is required, but the hinge mechanism
19 smoothly operates so that costs are reduced for manufacturing the
compressor.
-
-
A second preferred embodiment of the present invention will now be
described with reference to FIG. 5. The components that are different from those
of the first preferred embodiment are only described. The same reference
numerals denote the substantially identical components to those of the first
preferred embodiment, and the description is omitted.
-
FIG. 5 illustrates an enlarged longitudinal cross-sectional view of the
hinge mechanism 19 according to the second preferred embodiment of the
present invention. In the second preferred embodiment, the second hinge
element 51 is integrally formed with the swash plate 18, while the first hinge
element 52 is separately formed from the rotor 17. The first hinge element 52
integrally forms a base plate 56, a pair of the first protrusions 43 and a pair of the
cam portions 45. The first protrusions 43 extend from the rear end surface of the
base plate 56. The cam portions 45 are formed on the proximal portions of the
respective first protrusions 43. The rotor 17 that is separately formed from the first
hinge element 52 is simple and may apply forging as a manufacturing procedure.
-
The first hinge element 52 is loosely fitted into a shaft hole 17a at a shaft
55 thereof. The shaft 55 extends from the front end surface of the base plate 56.
The shaft hole 17a is formed through the rotor 17. Accordingly, the first hinge
element 52 is rotatable on the rotor 17 around the axis M of the shaft 55 (or the
shaft hole 17a) that is parallel with the axis L of the drive shaft 16. Namely, the
first hinge element 52 has the degree of freedom for rotation against the rotor 17.
The rotation of the first hinge element 52 is regulated in a predetermined angular
range on the rotor 17 in such a manner that an end surface 56a facing the drive
shaft 16 contacts the wall surface of the step 17b that is formed on the rotor 17.
-
In the second preferred embodiment, the first hinge element 52 is
rotatable on the rotor 17. Accordingly, even if the swash plate 18 inclines to twist
the second protrusions 44 in the engaging recess 41 by the axial load due to the
compression reactive force, stress due to the inclination rotates the first hinge
element 52 around the axis M on the rotor 17 so as to prevent the swash plate 18
from twisting the second protrusions 44.
-
A third preferred embodiment of the present invention will now be
described with reference to FIG. 6. The components that are different from those
of the first preferred embodiment are only described. The same reference
numerals denote the substantially identical components to those of the first
preferred embodiment, and the description is omitted.
-
FIG. 6 illustrates a plan view of the hinge mechanism 19 according to the
third preferred embodiment of the present invention. In the third preferred
embodiment, the engaging recess 41 is formed between a pair of the second
protrusions 44 in the second hinge element 51. The rotor 17 includes the single
first protrusion 43 at its rear end surface facing the engaging recess 41. The first
protrusion 43 extends toward the swash plate 18. The distal end of the first
protrusion 43 is inserted in the engaging recess 41. The first protrusion 43 has a
pair of side surfaces 43b, while each of the second protrusions 44 has a side
surface 44c that is a part of the inner surface of the engaging recess 41. The side
surfaces 43b of the first protrusion 43 contact the side surfaces 44c with a certain
amount of area. Accordingly, the rotational power of the rotor 17 is transmitted to
the swash plate 18 through one of the side surfaces 43b of the first protrusion 43
and one of the side surfaces 44c of the respective second protrusions 44.
-
The second hinge element 51 includes the cam portion 45 at the proximal
portions of the second protrusions 44 in the engaging recess 41. The distal end of
the first protrusion 43 forms a convex circular arc surface 43d and slidably
contacts a cam surface 45c of the cam portion 45. Accordingly, the axial load that
acts on the swash plate 18 due to the compression reactive force is received by
the cam surface 45c of the cam portion 45.
-
A fourth preferred embodiment of the present invention will now be
described with reference to FIG. 7. The components that are different from those
of the first preferred embodiment are only described. The same reference
numerals denote the substantially identical components to those of the first
preferred embodiment, and the description is omitted.
-
FIG. 7 illustrates an enlarged side view of the hinge mechanism 19
according to the fourth preferred embodiment of the present invention. In the
fourth preferred embodiment, the side surface 43a of the first protrusion 43
includes a guide groove 43c that extends along the direction of the cam surface
45a of the cam portion 45. The side surface 44a of the second protrusion 44
includes a guide protrusion 44d on the central axis S of the circular arc surface
44b, and the guide protrusion 44d is engagedly inserted in the guide groove 43c
for guiding the swash plate 18 to incline and slide relative to the drive shaft 16.
-
Even if the compression reactive force that acts on the swash plate 18
disappears due to the stop of the compressor, or even if the compression reactive
force that acts on the swash plate 18 decreases due to the operation of the
compressor in a minimum displacement volume, the swash plate assembly 18, 51
engages the rotor 17 by the engagement between the guide groove 43c and the
guide protrusion 44d. As a result, the swash plate assembly 18, 51 is prevented
from rattling due to vibration of a vehicle, with a consequence of preventing noise
generated on the compressor.
-
A fifth preferred embodiment of the present invention will now be
described with reference to FIG. 8. The components that are different from those
of the first preferred embodiment are only described. The same reference
numerals denote the substantially identical components to those of the first
preferred embodiment, and the description is omitted.
-
FIG. 8 illustrates an enlarged longitudinal cross-sectional view of the
hinge mechanism 19 according to the fifth preferred embodiment of the present
invention. In the fifth preferred embodiment, a slider 57 is interposed between the
circular arc surface 44b of the second protrusion 44 and the cam surface 45a of
the cam portion 45. Namely, the second protrusion 44 (the circular arc surface
44b) and the cam portion 45 (the cam surface 45a) slidably contact each other
through the slider 57.
-
The slider 57 includes a concave circular arc surface 57a and a planar
surface 57b. The concave circular arc surface 57a slides on the circular arc
surface 44b of the second protrusion 44. The planar surface 57b slides on the
cam surface 45a. Accordingly, the cam portion 45 and the slider 57 contact each
other with a certain amount of area, and the second protrusion 44 and the slider
57 contact each other with a certain amount of area. The areal contacts reduce
abrasion of the cam surface 45a and the circular arc surface 44b. That is, the
areal contacts contribute to improved durability of the hinge mechanism 19.
-
A sixth preferred embodiment of the present invention will now be
described with reference to FIG. 9. The components that are different from those
of the first preferred embodiment are only described. The same reference
numerals denote the substantially identical components to those of the first
preferred embodiment, and the description is omitted.
-
FIG. 9 illustrates a plan view of the hinge mechanism 19 according to the
sixth preferred embodiment of the present invention. In the sixth preferred
embodiment, the drive shaft 16 rotates in the direction of an arrow R, and the
hinge mechanism 19 is particularly configured to appropriately handle a state
when the drive shaft 16 rotates in the direction of the arrow R.
-
Namely, with respect to the hinge mechanism 19, a cam portion 45A and
a second protrusion 44A shown in the lower side of FIG. 9 in a compression cycle
mainly receive the axial load that acts on the swash plate 18 based upon the
compression reactive force, while the first protrusion 43 and another second
protrusion 44B shown in the upper side of FIG. 9 in a suction cycle transmit power
from the rotor 17 to the swash plate 18. Then, with respect to the second
protrusions 44A, 44B, when absolute amount of load, variation of the load and its
variation rate are considered, the second protrusion 44A for receiving the axial
load is hard in strength than the second protrusion 44B for power transmission.
-
Then, in the sixth preferred embodiment, the cam surface 45a of the cam
portion 45A for receiving the axial load is widened than the cam surface 45a of the
cam portion 45B for power transmission, while the second protrusion 44A for
receiving the axial load is thicker than the second protrusion 44B for power
transmission. Thus, the width of the circular arc surface 44b of the second
protrusion 44A is predetermined to be wide. Accordingly, the strength of the
second protrusion 44A for receiving the axial load is improved. In comparison to
the thickened second protrusions 44A, 44B, an increase in weight is relatively
small, while durability of the hinge mechanism 19 is ensured at equivalent level in
the sixth preferred embodiment.
-
A seventh preferred embodiment of the present invention will now be
described with reference to FIGs. 10 and 11. The components that are different
from those of the first preferred embodiment are only described. The same
reference numerals denote the substantially identical components to those of the
first preferred embodiment, and the description is omitted.
-
FIG. 10 illustrates an enlarged longitudinal cross-sectional view of the
hinge mechanism 19 according to the seventh preferred embodiment of the
present invention. FIG. 11 illustrates an enlarged perspective view of the hinge
mechanism 19 according to the seventh preferred embodiment of the present
invention. In the seventh preferred embodiment, a slider 60 is supported by the
drive shaft 16 so as to slide in the direction of the axis L. A fulcrum shaft 60a is
formed with the slider 60 and inclinably supports the swash plate 18.
-
With respect to the hinge mechanism 19, the cam portion 45 is omitted
from the first hinge element 52, and the first and second hinge elements 52, 51
engage each other through link arms 61.
-
Namely, the second hinge element 51 includes the single second
protrusion 44. An insertion hole 44e is formed through the distal end of the
second protrusion 44 in the direction perpendicular to the axis L of the drive shaft
16. The first hinge element 52 includes the single first protrusion 43 that radially
extends from the outer periphery of the rotor 17. An insertion hole 43e is formed
through the distal end of the first protrusion 43 in the direction perpendicular to
the axis L of the drive shaft 16.
-
A pair of the link arms 61 is arranged on each side of the distal ends of the
first and second protrusions 43, 44 and each of the link arms 61 has through
holes 61 a, 61b at both ends. One end of each link arm 61 is pivotally supported
through the through hole 61a by a pin 62 that is inserted into the through hole 43e
of the first protrusion 43. The other end of each link arm 61 is pivotally supported
through the through hole 61b by another pin 63 that is inserted through the
through hole 44e of the second protrusion 44. Accordingly, the swash plate 18
inclines around the pins 62, 63 in accordance with slide on the drive shaft 16.
-
According to the seventh preferred embodiment, the second hinge
element 51 is rotatable on the swash plate 18. Accordingly, even if the swash
plate 18 inclines to twist the second protrusion 44 between the link arms 61 by the
axial load due to the compression reactive force, stress due to the inclination
rotates the second hinge element 51 around the axis M on the swash plate 18 so
as to prevent the second protrusion 44 from twisting between the link arms 61.
-
An eighth preferred embodiment of the present invention will now be
described with reference to FIGs. 12 and 13. The components that are different
from those of the first preferred embodiment are only described. The same
reference numerals denote the substantially identical components to those of the
first preferred embodiment, and the description is omitted.
-
FIG. 12 illustrates a longitudinal cross-sectional view of the hinge
mechanism 19 according to the eighth preferred embodiment of the present
invention. FIG. 13 illustrates a plan view of the hinge mechanism 19 according to
the eighth preferred embodiment of the present invention. In the eighth preferred
embodiment, the second hinge element 51 includes the single second protrusion
44. A through hole 44f is formed through the distal end of the second protrusion
44. A pin 65 is fixedly inserted into the through hole 44f in the direction
perpendicular to the axis L of the drive shaft 16. With respect to the first hinge
element 52, a cam groove 43f is formed in each of the first protrusions 43. The
second protrusion 44 is inserted in between the first protrusions 43 so as to permit
power transmission from the rotor 17 to the swash plate 18 by contacting the side
surfaces 43a, 44a through a washer 67 and to slidably contact the inner surface
of the cam groove 43f by a cylindrical surface 65a of both sides of the pin 65 that
is inserted into the cam groove 43f.
-
Accordingly, the axial load that acts on the swash plate 18 due to the
compression reactive force and the like is received by the inner surface of the
cam groove 43f of the first protrusion 43 through the pin 65 of the second hinge
element 51. When the swash plate 18 varies its inclination angle, the hinge
mechanism 19 guides to increase the inclination angle of the swash plate 18 in
such a manner that the pin 65 (the cylindrical surface 65a) moves away from the
drive shaft 16 along the inner surface of the cam groove 43f on the side of the
rotor 17, while the distal end of the second protrusion 44 rotates around a central
axis of the pin 65.
-
According to the eighth preferred embodiment, the second hinge element
51 is rotatable on the swash plate 18. Accordingly, even if the swash plate 18
inclines to twist the second protrusion 44 between the first protrusions 43 and
also inclines to twist the pin 65 in the cam groove 43f by the axial load due to the
compression reactive force, stress due to the inclination rotates the second hinge
element 51 around the axis M on the swash plate 18 so as to avoid their twisting.
-
The present invention is not limited to the embodiments described above
but may be modified into the following alternative embodiments.
-
In alternative embodiments to those of the above first and third through
eighth preferred embodiments, the second hinge element 51 is made of iron
series sintered metal. In alternative embodiments to those of the above second
preferred embodiment, the first hinge element 52 is made of iron series sintered
metal. Accordingly, the sintered metal effectively holds lubricating oil so that
sliding performance and seizure resistance improve between the first and second
hinge elements 52, 51. Incidentally, the lubricating oil is supplied to the crank
chamber 15 with its mist contained in the refrigerant gas.
-
In alternative embodiments to those of the above preferred embodiments,
the second hinge element 51 is rotatable on the swash plate 18, while the first
hinge element 52 is rotatable on the rotor 17.
-
In alternative embodiments to those of the above second preferred
embodiment, the first protrusion 43 is only rotatable on the rotor 17 in the
components 43, 45 of the first hinge element 52, while the cam portion 45 is fixed
to the rotor 17. Similarly, in alternative embodiments to those of the above third
preferred embodiment, the second protrusion 44 is only rotatable on the swash
plate 18 in the components 44, 45 of the second hinge element 51, while the cam
portion 45 is fixed to the swash plate 18.
-
In alternative embodiments to those of the above first and third through
eighth preferred embodiments, a plurality of the second protrusions 44 is
separately formed, and each of the second protrusions 44 is individually rotatable
on the swash plate 18.
-
In alternative embodiments to those of the above preferred embodiments,
a plane bearing or a rolling bearing is interposed between the shaft portion 48 or
55 and the shaft hole 18c or 17a, respectively. Also, solid lubricant such as
fluororesin and molybdenum disulfide is applied on at least one of the outer
circumferential surface of the shaft portion 48 or 55 and the inner circumferential
surface of the shaft hole 18c or 17a, respectively. Accordingly, the second hinge
element 51 smoothly rotates on the swash plate 18 according to the first and third
through eighth preferred embodiments or the first hinge element 52 smoothly
rotates on the rotor 17 according to the second preferred embodiment. As a result,
the swash plate 18 smoothly varies its inclination angle. That is, the compressor
smoothly varies its displacement volume.
-
In alternative embodiments to those of the above preferred embodiments,
at least one of the first and second hinge elements 52, 51 includes a shaft hole,
while the rotor 17 or the swash plate 18 on which the hinge element is arranged
includes a shaft portion. Also, a pair of the first hinge element 52 and the rotor 17
or a pair of the second hinge element 51 and the swash plate 18 respectively
includes shaft holes, and a shaft member is interposed between the shaft holes
by inserting the shaft member into the shaft holes.
-
In alternative embodiments to those of the above preferred embodiments,
the first hinge element 52 or the second hinge element 51 has the degree of
freedom for slide relative to the rotor 17 or the swash plate 18, respectively.
-
In alternative embodiments to those of the above preferred embodiments,
at least one of the first and second hinge elements 52, 51 has two dimensional
degree of freedom for motion against the rotor 17 or the swash plate 18 on which
the hinge element is arranged. For example, one of the first and second hinge
elements 52, 51 has the degree of freedom for rotation and for slide relative to the
rotor 17 or the swash plate 18, respectively.
-
In alternative embodiments to those of the above preferred embodiments,
an engaging groove is recessed in a merely disc-shaped rotor (for example, the
shape from which the first and second hinge elements 52, 51 are omitted in the
above preferred embodiments) or a disc of a swash plate.
-
In alternative embodiments to those of the above preferred embodiments,
the compressor is a variable displacement compressor that has a double-headed
piston.
-
In alternative embodiments to those of the above preferred embodiments,
the compressor is a wobble type variable displacement compressor that has a
wobble plate or a cam plate.
-
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.
-
A variable displacement compressor has a housing, a piston, a drive shaft,
a rotor, a cam plate and a hinge mechanism. The hinge mechanism between the
rotor and the cam plate guides the cam plate to incline and slide relative to the
drive shaft. Thus, the displacement volume of the compressor is varied. The
rotation of the drive shaft is converted to the reciprocation of the piston through
the rotor, the hinge mechanism and the cam plate. The hinge mechanism
includes first and second hinge elements that are respectively provided on the
rotor and on the cam plate and engage each other. At least one of the first and
second hinge elements has a degree of freedom for motion against the rotor
and/or the cam plate to which it belongs.