Expansible chamber devices – Rotating cylinder – Plural cylinders
Reexamination Certificate
1999-09-20
2001-12-04
Look, Edward K. (Department: 3745)
Expansible chamber devices
Rotating cylinder
Plural cylinders
C092S158000
Reexamination Certificate
active
06324959
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a piston pump motor, and more particularly to a shape of a piston and a cylinder block in inclined shaft type and swash plate type hydraulic pumps which can be applied to a high rotational speed.
BACKGROUND OF THE INVENTION
Conventionally, there has been known a piston pump which rotates a cylinder block apparatus via a drive shaft by a power of a drive source and oscillates a piston within a cylinder block, thereby sucking an oil from a tank and discharging a high pressurized oil so as to convert a mechanical energy to a fluid energy. Further, there has been known a piston motor which introduces a high pressurized oil within a cylinder block from a pump and oscillates a piston, thereby rotating a cylinder block apparatus and a drive shaft so as to convert a fluid energy to a mechanical energy. In this case, a basic structure of the cylinder block apparatus is common in both of the piston pump and the piston motor.
An embodiment of an inclined shaft type piston motor having a cylinder block apparatus
30
will be shown in
FIG. 6. A
drive shaft
31
is supported by bearings
33
and
34
received in a case
32
so as to be rotated. A flange portion
31
a
is integrally formed in an end side of the drive shaft
31
. A ball
35
a
integrally formed with a center shaft
35
is assembled on a rotary shaft core X of the drive shaft
31
in the flange portion
31
a,
and the center shaft
35
is oscillated in a vertical direction at a predetermined inclination angle with respect to the rotary shaft core X of the drive shaft
31
an inclination angle control apparatus
60
.
A plurality of piston assemblies
36
are arranged in the flange portion
31
a
from the rotary shaft core X of the drive shaft
31
in such a manner as to be on the same circumference. The piston assemblies
36
are constituted by piston rods
37
and pistons
38
and slidably connected. The piston rod
37
has spherical portions
37
a
and
37
b
at both ends and both portions are connected by a rod
37
c.
The piston
38
is constituted by a circular column having a circular hole pierced in an axial direction from a side of an end surface, and a bottom of the hole is formed in a semispherical shape. The spherical portion
37
a
at one end portion of the piston rod
37
is inserted to the semispherical portion in the bottom of the hole of the piston
38
, and both elements are connected by deforming an outer diameter of the piston
38
. The piston
38
can be oscillated in a range at which the piston rod
37
is brought into contact with the hole. Further, the spherical portion
37
b
in the other end portion of the piston rod
37
is mounted to the flange portion
31
a
of the drive shaft
31
in such a manner as to freely oscillate. Accordingly, the piston
38
is mounted to each of the drive shaft
31
and the piston rod
37
in such a manner as to freely oscillate. An outer diameter in a side of the other end surface of the piston
38
is inserted to a cylinder block
42
mentioned below in a sealed manner, thereby sealing a high pressurized oil acting on the side of the other end surface of the piston
38
by an outer circumference portion
38
a
(shown in
FIGS. 7A and 7B
) of the piston
38
.
A shape of the outer circumference portion
38
a
of the piston
38
includes a straight shape without a groove (
FIG. 7A
) and a shape in which a plurality of labyrinth grooves
38
b
not communicating with each other in a longitudinal direction are cut (FIG.
7
B).
A case drain
39
shown in
FIG. 6
is formed in an inner portion of the case
32
, and an oil leaking from a gap between the piston assembly
36
and the cylinder block
42
is discharged from a drain port
41
to a tank (not shown) via a case drain
39
. Since a pressure is uniformly distributed all around the periphery due to a function of the labyrinth groove
38
b,
the piston
38
is held near a center of the hole
42
b
of the cylinder block
42
. As a result, the piston
38
is not directly brought into contact with the hole
42
b
even when the piston
38
oscillates within the hole
42
b,
so that a heat generation due to a sliding friction can be restricted to a low level. Further, since the labyrinth groove
38
b
projects to a side of the case drain
39
having a low temperature from the cylinder block
42
due to an oscillation of the piston
38
, the high temperature oil in the labyrinth groove
38
b
can be discharged or cooled.
The cylindrical cylinder block
42
shown in
FIG. 8
oscillates in a vertical direction with respect to the rotary shaft core X of the drive shaft
31
in accordance with an oscillation in a vertical direction of a center shaft
35
by the inclination angle control apparatus
60
mentioned above. Accordingly, the cylinder block
42
rotates around a rotary shaft core Y of the center shaft
35
.
The side of one end surface of the cylinder block
42
is formed in a concave spherical surface shape, and the spherical surface has a plurality of suction and discharge ports
42
a
and is slidably brought into contact with a convex spherical surface of the valve plate
43
. A plurality of cylinder block holes
42
b
(hereinafter, refer to as cylinder holes
42
b
) are pierced in the side of the other end surface of the cylinder block
42
at the same number as that of the piston assemblies
36
mounted to the flange portion
31
a
at an equal interval on a circumference inside the cylinder block
42
. These cylinder holes
42
b
are connected to a plurality of suction and discharge ports
42
a,
and a plurality of piston assemblies
36
are inserted to each of the cylinder holes
42
b
at a sealing interval in such a manner as to freely oscillate. The high pressurized oil from each of the suction and discharge ports
42
a
acts on the end surface of each of the piston assemblies
36
.
The ball
35
a
in the side of one end of the center shaft
35
is assembled in the flange portion
31
a,
however, the side of the other end is supported by the bearing
44
of the valve plate
43
. The valve plate inclines on a sliding surface
45
having a concave spherical surface shape and formed in the inclination angle control apparatus
60
around a core Z of the ball
35
a
of the center shaft
35
. In this case, the inclination angle corresponds to an inclination of the rotary core Y of the cylinder block
42
with respect to the rotary shaft core X of the drive shaft
31
, and is adjusted by the inclination angle control apparatus
60
.
In this case, when adjusting the inclination angle a little, the cylinder block
42
comes near to the rotary shaft core X of the drive shaft
31
, so that the piston assembly
36
is further inserted within the cylinder block
42
and a stroke S (a difference of at amount between forward and backward positions of the piston) becomes small. As a result, since a space capacity between the cylinder block
42
and the piston assembly
36
is reduced, a number of oscillation per a unit time of the piston assembly
36
is increased in the case of the constant inlet amount, so that a number of rotation of the drive shaft
31
connected to the cylinder block
42
is increased. That is, when the inclination angle is reduced, it becomes a high speed rotation, and inversely when the inclination angle is increased, it becomes a low speed rotation. Further, when the inclination angle is 0, that is, the rotary shaft core X of the drive shaft
31
and the rotary shaft core Y of the cylinder block
42
are on the same axis, the stroke S becomes 0, the piston assembly
36
is not going to oscillate, and the drive shaft
31
is not going to rotate.
A sheet
46
and a spring
47
are arranged between the center shaft
35
and the cylinder block
42
, thereby keeping a contact state in the spherical sliding surface formed by the cylinder block
42
and the valve plate
43
by a pressing force of the spring
47
. The suction and discharge port
42
a
of the cylinder block
42
is connected to an inlet for a pressurized and a discharge oil outlet (not shown) of
Akasaka Toshiyuki
Morita Koichi
Nunotani Sadao
Komatsu Ltd.
Leslie Michael
Look Edward K.
Sidley Austin Brown & Wood
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