Machine element or mechanism – Mechanical movements – Rotary to or from reciprocating or oscillating
Reexamination Certificate
2000-11-07
2002-10-29
Joyce, William C. (Department: 3682)
Machine element or mechanism
Mechanical movements
Rotary to or from reciprocating or oscillating
C417S222100
Reexamination Certificate
active
06470761
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a connecting link between the rotor and the cam plate of a variable displacement swash plate compressor.
As shown in
FIG. 1
, there is known a connecting link between a rotor
2
supported by a driving shaft
1
to rotate synchronously with the driving shaft
1
and a variable inclination cam plate
3
supported by the driving shaft
1
of a variable displacement swash plate compressor. The cam plate
3
can incline between the minimum inclination shown in FIG.
1
(
a
) and the maximum inclination shown in FIG.
1
(
b
). The connecting link comprises a first arm
2
a
extending from the rotor
2
toward the cam plate
3
and a second arm
3
a
extending from the cam plate
3
toward the rotor
2
. The first arm
2
a
is provided with an oval guide hole
2
a
, extending at right angles to a plane defined by the central axis
1
X of the driving shaft
1
and the top dead center
3
X of the cam plate
3
. The second arm
3
a
is provided with a pin
4
extending at right angles to the plane. The pin
4
has a circular cross section and is inserted in the oval guide hole
2
a
7
with its circumferential side surface abutted against both the long side surface of the oval guide hole
2
a
7
distant from the rotor
2
and the long side surface of the oval guide hole
2
a
7
close to the rotor
2
.
In FIG.
1
(
c
), the abutting point of the surface of the pin
4
against the long side surface of the oval guide hole
2
a
7
at the minimum inclination of the cam plate
3
is indicated by a solid triangle, while the abutting point of the surface of the pin
4
against the long side surface of the oval guide hole
2
a
7
at the maximum inclination of the cam plate
3
is indicated by an open triangle. As seen from FIG.
1
(
c
), the abutting point indicated by the solid triangle is close to the abutting point indicated by the open triangle. Therefore, a quite narrow region of the surface of the pin
4
abuts repeatedly against the long side surface of the oval guide hole
2
a
7
following the fluctuation of the inclination of the cam plate
3
.
High contact pressure is generated at the abutting point between the surface of the pin
4
and the long side surface of the oval guide hole
2
a
7
close to the rotor
2
because a thrust force is transmitted from the cam plate
3
to rotor
2
during the operation of the compressor. Therefore, if the quite narrow region of the surface of the pin
4
abuts repeatedly against the long side surface of the oval guide hole
2
a
7
close to the rotor
2
following the fluctuation of the inclination of the cam plate
3
, the surface of the pin
4
in the narrow region is rapidly worn away, the pin
4
rapidly wears out, and the connecting link rapidly wears out.
As shown in
FIG. 2
, there is known a connecting link between a rotor
12
supported by a driving shaft
11
to rotate synchronously with the driving shaft
11
and a variable inclination cam plate
13
supported by the driving shaft
11
of a variable displacement swash plate compressor.
The cam plate
13
can incline between the minimum inclination shown in FIG.
2
(
a
) and the maximum inclination shown in FIG.
2
(
b
). The connecting link comprises a first arm
12
a
extending from the rotor
12
toward the cam plate
13
and a pin
14
extending from the cam plate
13
toward the rotor
12
. The first arm
12
a
is provided with a guide hole
12
a
7
extending parallel to a plane defined by the central axis
11
X of the driving shaft
11
and the top dead center
13
X of the cam plate
13
. The pin
14
is provided with a ball
14
a
at its tip. The pin
14
is inserted in the guide hole
12
a
7
with the ball
14
a
abutted against the side surface of the guide hole
12
a
7
.
In FIG.
2
(
c
), the abutting point of the surface of the ball
14
a
against the side surface of the guide hole
12
a
7
at the minimum inclination of the cam plate
13
is indicated by a solid triangle, while the abutting point of the surface of the ball
14
a
against the side surface of the guide hole
12
a
7
at the maximum inclination of the cam plate
13
is indicated by an open triangle. As seen from FIG.
2
(
c
), the abutting point indicated by the solid triangle is close to the abutting point indicated by the open triangle.
Therefore, a quite narrow region of the surface of the ball
14
a
abuts repeatedly against the side surface of the guide hole
12
a
7
following the fluctuation of the inclination of the cam plate
13
.
High contact pressure is generated at the abutting point between the surface of the ball
14
a
and the side surface of the guide hole
12
a
7
close to the rotor
12
because a thrust force is transmitted from the cam plate
13
to rotor
12
during the operation of the compressor. Therefore, if the quite narrow region of the surface of the ball
14
a
abuts repeatedly against the side surface of the guide hole
12
a
7
close to the rotor
12
following the fluctuation of the inclination of the cam plate
13
, the surface of the ball
14
a
in the narrow region is rapidly worn away, the ball
14
a
rapidly wears out, and the connecting link rapidly wears out.
SUMMARY OF THE INVENTION
An object of the present invention is to provide a connecting link between the rotor and the cam plate of a variable displacement swash plate compressor superior in durability to the conventional connecting link.
In accordance with one aspect of the present invention, there is provided a connecting link between a rotor supported by a driving shaft to rotate synchronously with the driving shaft and a variable inclination cam plate supported by the driving shaft of a variable displacement swash plate compressor, comprising a first arm extending from the rotor toward the cam plate and a second arm extending from the cam plate toward the rotor, wherein the first arm is provided with an oval guide hole extending at right angles to a plane defined by the central axis of the driving shaft and the top dead center of the cam plate, the second arm is provided with a pin extending at right angles to the plane, the pin has a sector-shaped cross section with rounded apex, and the pin is inserted in the oval guide hole with the apex of the sector-shaped cross section abutted against the long side surface of the oval guide hole distant from the rotor and the circular arc portion of the sector-shaped cross section abutted against the long side surface of the oval guide hole close to the rotor
In the connecting link of this aspect of the present invention, the cross section of the pin inserted into the oval guide hole of the rotor is sector-shaped. Therefore, the radius of curvature of the circular arc portion of the sector-shaped cross section of the pin inserted into the oval guide hole (with the circular arc portion abutted against the long side surface of the oval guide hole close to the rotor) can be made larger than that of the circular cross section of the pin of the conventional connecting link shown in FIG.
1
.
In the connecting link of this aspect of the present invention, the radius of curvature of the circular arc portion of the sector-shaped cross section of the pin is larger than that of the circular cross section of the pin of the conventional connecting link shown in FIG.
1
. Therefore, the distance between the abutting point of the surface of the pin against the long side surface of the oval guide hole close to the rotor at the minimum inclination of the cam plate and the abutting point of the surface of the pin against the long side surface of the oval guide hole close to the rotor at the maximum inclination of the cam plate is larger than that of the conventional connecting link shown in FIG.
1
. Thus, the region of the surface of the pin abutting repeatedly against the long side surface of the oval guide hole close to the rotor following the fluctuation of the inclination of the cam plate is larger than that of the conventional connecting link.
High contact pressure is generated at the abutting point between the surface of the pin and
Nakamura Shinji
Tagami Shinji
Baker & Botts L.L.P.
Joyce William C.
Sanden Corporation
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