U.S. patent application number 11/498016 was filed with the patent office on 2006-11-30 for axial piston device.
Invention is credited to Manabu Kawakami, Shigenori Sakikawa.
Application Number | 20060269421 11/498016 |
Document ID | / |
Family ID | 37395886 |
Filed Date | 2006-11-30 |
United States Patent
Application |
20060269421 |
Kind Code |
A1 |
Sakikawa; Shigenori ; et
al. |
November 30, 2006 |
Axial piston device
Abstract
There is provided an axial piston device with which a pair of
first oil passages and a drain oil passage for allowing at least
one of the first oil passages to communicate with an oil sump. The
axial piston device includes a rotary valve rotated around its axis
so as to take a shutoff position/a communication position at which
the drain oil passage is respectively shut off and communicated.
The rotary valve includes a main body, a small-diameter portion
that is contracted with a step from the main body, a flange portion
that is enlarged from the small-diameter portion with a step, and a
communication groove formed on the outer peripheral surface of the
main body. The communication groove is formed at the position in
the circumferential direction so as to be fluidly shutoff with
respect to an upstream-side drain oil passage of the drain oil
passage when the rotary valve is positioned at the shutoff
position, and fluidly connected to the upstream-side drain oil
passage when the rotary valve is positioned at the communication
position.
Inventors: |
Sakikawa; Shigenori; (Hyogo,
JP) ; Kawakami; Manabu; (Hyogo, JP) |
Correspondence
Address: |
STERNE, KESSLER, GOLDSTEIN & FOX PLLC
1100 NEW YORK AVENUE, N.W.
WASHINGTON
DC
20005
US
|
Family ID: |
37395886 |
Appl. No.: |
11/498016 |
Filed: |
August 3, 2006 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
10931095 |
Sep 1, 2004 |
|
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11498016 |
Aug 3, 2006 |
|
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Current U.S.
Class: |
417/53 ;
417/222.1; 417/269 |
Current CPC
Class: |
F16H 39/14 20130101;
F16H 61/4165 20130101; F04B 1/2064 20130101; F04B 23/106 20130101;
F04B 1/2021 20130101; F16H 61/4043 20130101; F04B 1/2042 20130101;
F16H 61/4139 20130101; F16H 61/40 20130101 |
Class at
Publication: |
417/053 ;
417/269; 417/222.1 |
International
Class: |
F04B 49/06 20060101
F04B049/06; F04B 1/26 20060101 F04B001/26; F04B 27/08 20060101
F04B027/08 |
Foreign Application Data
Date |
Code |
Application Number |
Aug 5, 2005 |
JP |
2005-228552 |
Claims
1. An axial piston device comprising: a rotary shaft rotating about
its axis; a cylinder block supported on the rotary shaft in a
relatively non-rotatable manner; a plurality of pistons
accommodated within the cylinder block in a slidable manner in the
axial direction; a swash plate engaging directly or indirectly free
ends of the pistons; a plate having a contact surface which is
brought into contact with discharge/suction ports of the cylinder
block, the plate being provided with a pair of first oil passages
having first ends opened to the contact surface so as to fluidly
connect with the discharge/suction ports of the cylinder block and
second ends opened to a surface of the plate, and a drain oil
passage for allowing at least one of the first oil passages to
communicate with an oil sump; a rotary valve operated and rotated
around its axis so as to take a shutoff position at which the drain
oil passage is shut off and a communication position at which the
drain oil passage is communicated; the drain oil passage including
an upstream-side drain oil passage fluidly connected to at least
one of the pair of first oil passages, a downstream-side drain oil
passage fluidly connected to the oil sump, and a disposing hole
that intersects both the upstream-side drain oil passage and the
downstream-side drain oil passage and that has a base end opened to
the outer surface of the plate so that the rotary valve is inserted
into the disposing hole through the base end; the rotary valve
including a main body that has an outer peripheral surface liquid
tightly contacting the inner peripheral surface of the disposing
hole at an upstream-side connecting point where the upstream-side
drain oil passage and the disposing hole intersect to each other, a
small-diameter portion that is contracted with a step from the main
body and that is extended towards the distal end side of the
disposing hole from the main body, the small-diameter portion
defining a space between the inner peripheral surface of the
disposing hole and the outer peripheral surface of the
small-diameter portion, a flange portion that is enlarged from the
small-diameter portion with a step and is positioned at the distal
end side of the disposing hole from a downstream-side connecting
point where the downstream-side drain oil passage and the disposing
hole intersect to each other, the flange portion having an outer
peripheral surface that liquid tightly contacts the inner
peripheral surface of the disposing hole, and a communication
groove formed on the outer peripheral surface of the main body so
as to extend from the position in the axial direction corresponding
to the upstream-side connecting point to the space; and the
communication groove being formed at the position in the
circumferential direction so as to be fluidly shutoff with respect
to the upstream-side drain oil passage when the rotary valve is
positioned at the shutoff position, and fluidly connected to the
upstream-side drain oil passage when the rotary valve is positioned
at the communication position.
2. An axial piston device according to claim 1, further comprising:
a housing surrounding the cylinder block, wherein the housing is
configured such that an inside space thereof is used as the oil
sump.
3. An axial piston device according to claim 2, wherein the housing
is configured in such a manner as to surround the plate in addition
to the cylinder block, and the second ends of the pair of first oil
passages are fluid-connected to conduit members supported by the
housing astride inward and outward of the housing.
4. An axial piston device according to claim 2, further comprising:
a housing body having an opening formed at a first end thereof, the
housing body surrounding the cylinder block, wherein the plate is
configured in such a manner as to be connected to the housing body
so as to close the opening formed at the first end of the housing
body, and the housing body and the plate form the housing.
5. An axial piston device comprising: a rotary shaft rotating about
its axis; a cylinder block supported on the rotary shaft in a
relatively non-rotatable manner; a plurality of pistons
accommodated within the cylinder block in a slidable manner in the
axial direction; a swash plate engaging directly or indirectly free
ends of the pistons; a plate having a contact surface which is
brought into contact with discharge/suction ports of the cylinder
block, the plate being provided with a pair of first oil passages
having first ends opened to the contact surface so as to fluidly
connect with the discharge/suction ports of the cylinder block and
second ends opened to a surface of the plate, and a drain oil
passage for allowing at least one of the first oil passages to
communicate with an oil sump; a rotary valve operated and rotated
around its axis so as to take a shutoff position at which the drain
oil passage is shut off and a communication position at which the
drain oil passage is communicated; the drain oil passage including
an upstream-side drain oil passage fluidly connected to at least
one of the pair of first oil passages, a downstream-side drain oil
passage fluidly connected to the oil sump, and a disposing hole
that intersects both the upstream-side drain oil passage and the
downstream-side drain oil passage and that has a base end opened to
the outer surface of the plate so that the rotary valve is inserted
into the disposing hole through the base end; the rotary valve
including a main body that has an outer peripheral surface liquid
tightly contacting the inner peripheral surface of the disposing
hole at an upstream-side connecting point where the upstream-side
drain oil passage and the disposing hole intersect to each other
and at a downstream-side connecting point where the downstream-side
drain oil passage and the disposing intersect to each other; and a
communication oil passage formed at the main body so as to have a
first end and a second end respectively opened to the outer
peripheral surface at the positions in the axial direction
respectively corresponding to the upstream-side connecting point
and the downstream-side connecting point; the first end of the
communication oil passage being opened to the outer peripheral
surface at the position in the circumferential direction so as to
be fluidly shutoff with respect to the upstream-side drain oil
passage when the rotary valve is positioned at the shutoff position
and fluidly connected to the upstream-side drain oil passage when
the rotary valve is positioned at the communication position; and
the second end of the communication oil passage being opened to the
outer peripheral surface at the position in the circumferential
direction so as to be fluidly connected to the downstream-side
drain oil passage when the rotary valve is positioned at the
communication position.
6. An axial piston device according to claim 5, further comprising:
a housing surrounding the cylinder block, wherein the housing is
configured such that an inside space thereof is used as the oil
sump.
7. An axial piston device according to claim 6, wherein the housing
is configured in such a manner as to surround the plate in addition
to the cylinder block, and the second ends of the pair of first oil
passages are fluid-connected to conduit members supported by the
housing astride inward and outward of the housing.
8. An axial piston device according to claim 6, further comprising:
a housing body having an opening formed at a first end thereof, the
housing body surrounding the cylinder block, wherein the plate is
configured in such a manner as to be connected to the housing body
so as to close the opening formed at the first end of the housing
body, and the housing body and the plate form the housing.
9. An axial piston device comprising: a rotary shaft rotating about
its axis; a cylinder block supported on the rotary shaft in a
relatively non-rotatable manner; a plurality of pistons
accommodated in the cylinder block in a slidable manner in the
axial direction; a swash plate engaging directly or indirectly free
ends of the pistons; a plate having a contact surface which is
brought into contact with discharge/suction ports of the cylinder
block, the plate being provided with a pair of first oil passages
having first ends opened to the contact surface so as to fluidly
connect with the discharge/suction ports of the cylinder block and
second ends opened to a surface of the plate, and a drain oil
passage for allowing at least one of the first oil passages to
communicate with an oil sump; a rotary valve operated and rotated
around its axis so as to take a shutoff position at which the drain
oil passage is shut off and a communication position at which the
drain oil passage is communicated; the pair of oil passages being
substantially parallel to each other with the rotary shaft
sandwiched therebetween and extended in a direction orthogonal to
the axis of the rotary shaft; and the rotary valve being inserted
in a rotatable manner around an axis into a disposing hole formed
at the plate so as to be substantially parallel to the pair of oil
passages between the pair of oil passages.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to an axial piston device such
as a pump unit or a motor unit.
[0003] 2. Related Art
[0004] An axial piston device comprising a cylinder block rotated
about an axis and a piston accommodated in a slidable manner in an
axial direction with respect to the cylinder block while being
rotated about the axis together with the cylinder block has been
widely utilized as a pump unit to be used as a hydraulic source
with respect to hydraulic equipment such as a hydraulic motor or as
a motor unit to be hydraulically driven by a hydraulic source such
as a hydraulic pump.
[0005] Hereinafter, description will be given of a conventional
axial piston device by way of a pump unit.
[0006] A conventional pump unit comprises, for example, a housing
which has a housing body opened at a first end thereof and a plate
attached to the first end of the housing body, a pump shaft which
is supported by the housing and is driven by a drive source, and a
pump body which is accommodated inside the housing and is rotatably
driven by the pump shaft, wherein each of a discharge port and a
suction port of the pump body is hydraulically connected in
circulation to a corresponding hydraulic device such as a hydraulic
motor.
[0007] That is to say, a pair of oil passages communicating with
the discharge port and the suction port of the pump body,
respectively, is formed at the plate. Thus, pressurized oil is
supplied from the pump body to the hydraulic device via one of the
oil passages, and further, return oil is returned to the pump body
from the hydraulic device via the other one of the oil
passages.
[0008] In the pump unit after assembly, air is mixed inside the
pair of oil passages; therefore, the pair of oil passages is
required to be deaerated.
[0009] In other words, the pump unit and the hydraulic device are
connected via the pair of oil passages, thereby forming a
circulation circuit, wherein the circulation circuit is required to
be sufficiently deaerated upon filling oil into the circulation
circuit.
[0010] In regard to this point, in the conventional pump unit, a
drain oil passage for allowing the pair of oil passages to
communicate with an oil sump is formed at the plate, and further, a
shutoff valve is disposed inside the drain oil passage in such a
manner as to be positionally adjusted in an axial direction (see
U.S. Pat. No. 6,332,393).
[0011] In particular, a valve seat is provided at the drain oil
passage. The position of the shutoff valve in the axial direction
can be adjusted in such a manner that the shutoff valve can take a
shutoff position at which the shutoff valve is in contact with the
valve seat so as to have the drain oil passage shut off and a
communication position at which the shutoff valve is apart from the
valve seat in the axial direction so as to have the drain oil
passage communicated.
[0012] In this conventional pump unit, the pair of oil passages can
communicate with or can be cut out of the oil sump by operating the
shutoff valve, with an attendant problem of impossibility of speedy
switching between the communication and shutoff.
[0013] Namely, in the conventional pump unit, the position of the
shutoff valve in the axial direction can be adjusted with respect
to the plate owing to screw connection. Consequently, in order to
move the shutoff valve from the shutoff position to the
communication position at which a sufficient opening width is
secured, the shutoff valve must be rotated on an axis many
times.
[0014] The present invention has been accomplished in view of the
above prior art.
[0015] One object of the present invention is to provide an axial
piston device in which an oil passage can be reliably and rapidly
deaerated, and in which the rotary valve can be prevented from
being pushed and moved toward the direction of exiting from a
disposing hole, into which the rotary valve is inserted, during
deaeration.
[0016] Another object of the present invention is to provide an
axial piston device in which an oil passage can be reliably and
rapidly deaerated, and in which an oil passage structure for
deaerating could be simplified.
SUMMARY OF THE INVENTION
[0017] According to the present invention, there is provided an
axial piston device including: a rotary shaft rotating about its
axis; a cylinder block supported on the rotary shaft in a
relatively non-rotatable manner; a plurality of pistons
accommodated within the cylinder block in a slidable manner in the
axial direction; a swash plate engaging directly or indirectly free
ends of the pistons; a plate having a contact surface which is
brought into contact with discharge/suction ports of the cylinder
block, the plate being provided with a pair of first oil passages
having first ends opened to the contact surface so as to fluidly
connect with the discharge/suction ports of the cylinder block and
second ends opened to a surface of the plate, and a drain oil
passage for allowing at least one of the first oil passages to
communicate with an oil sump; and a rotary valve operated and
rotated around its axis so as to take a shutoff position at which
the drain oil passage is shut off and a communication position at
which the drain oil passage is communicated.
[0018] The drain oil passage includes an upstream-side drain oil
passage fluidly connected to at least one of the pair of first oil
passages; a downstream-side drain oil passage fluidly connected to
the oil sump; and a disposing hole that intersects both the
upstream-side drain oil passage and the downstream-side drain oil
passage and that has a base end opened to the outer surface of the
plate so that the rotary valve is inserted into the disposing hole
through the base end.
[0019] The rotary valve includes a main body that has an outer
peripheral surface liquid tightly contacting the inner peripheral
surface of the disposing hole at an upstream-side connecting point
where the upstream-side drain oil passage and the disposing hole
intersect to each other; a small-diameter portion that is
contracted with a step from the main body and that is extended
towards the distal end side of the disposing hole from the main
body, the small-diameter portion defining a space between the inner
peripheral surface of the disposing hole and the outer peripheral
surface of the small-diameter portion; a flange portion that is
enlarged from the small-diameter portion with a step and is
positioned at the distal end side of the disposing hole from a
downstream-side connecting point where the downstream-side drain
oil passage and the disposing hole intersect to each other, the
flange portion having an outer peripheral surface that liquid
tightly contacts the inner peripheral surface of the disposing
hole; and a communication groove formed on the outer peripheral
surface of the main body so as to extend from the position in the
axial direction corresponding to the upstream-side connecting point
to the space.
[0020] The communication groove is formed at the position in the
circumferential direction so as to be fluidly shutoff with respect
to the upstream-side drain oil passage when the rotary valve is
positioned at the shutoff position, and fluidly connected to the
upstream-side drain oil passage when the rotary valve is positioned
at the communication position.
[0021] According to the configuration, since the rotary valve
switches the communicating state and the shutoff state of the drain
oil passage, the pair of first oil passages can be deaerated
reliably and rapidly as much as possible.
[0022] Furthermore, according to the configuration, even if the oil
pressure is increased in the space when the rotary valve is
positioned at the communication position so that the pressure oil
in the first oil passages is discharged into the oil sump, the
pushing force produced by the oil pressure to push the rotary valve
towards the base end side of the disposing hole is canceled out by
the pushing force produced by the oil pressure to push the rotary
valve towards the distal end side of the disposing hole. Therefore,
it could be effectively prevented that the rotary valve is pushed
and moved towards the direction of exiting from the disposing hole
(i.e. the rotary valve is floated from the disposing hole) when the
rotary valve is positioned at the communication position.
[0023] According to the present invention, there is still provided
an axial piston device including: a rotary shaft rotating about its
axis; a cylinder block supported on the rotary shaft in a
relatively non-rotatable manner; a plurality of pistons
accommodated within the cylinder block in a slidable manner in the
axial direction; a swash plate engaging directly or indirectly free
ends of the pistons; a plate having a contact surface which is
brought into contact with discharge/suction ports of the cylinder
block, the plate being provided with a pair of first oil passages
having first ends opened to the contact surface so as to fluidly
connect with the discharge/suction ports of the cylinder block and
second ends opened to a surface of the plate, and a drain oil
passage for allowing at least one of the first oil passages to
communicate with an oil sump; and a rotary valve operated and
rotated around its axis so as to take a shutoff position at which
the drain oil passage is shut off and a communication position at
which the drain oil passage is communicated.
[0024] The drain oil passage includes an upstream-side drain oil
passage fluidly connected to at least one of the pair of first oil
passages; a downstream-side drain oil passage fluidly connected to
the oil sump; and a disposing hole that intersects both the
upstream-side drain oil passage and the downstream-side drain oil
passage and that has a base end opened to the outer surface of the
plate so that the rotary valve is inserted into the disposing hole
through the base end.
[0025] The rotary valve includes a main body having an outer
peripheral surface that liquid tightly contacting the inner
peripheral surface of the disposing hole at an upstream-side
connecting point where the upstream-side drain oil passage and the
disposing hole intersect to each other and at a downstream-side
connecting point where the downstream-side drain oil passage and
the disposing intersect to each other; and a communication oil
passage formed at the main body so as to have a first end and a
second end respectively opened to the outer peripheral surface at
the positions in the axial direction respectively corresponding to
the upstream-side connecting point and the downstream-side
connecting point.
[0026] The first end of the communication oil passage is opened to
the outer peripheral surface at the position in the circumferential
direction so as to be fluidly shutoff with respect to the
upstream-side drain oil passage when the rotary valve is positioned
at the shutoff position and fluidly connected to the upstream-side
drain oil passage when the rotary valve is positioned at the
communication position.
[0027] The second end of the communication oil passage is opened to
the outer peripheral surface at the position in the circumferential
direction so as to be fluidly connected to the downstream-side
drain oil passage when the rotary valve is positioned at the
communication position.
[0028] According to the configuration, since the rotary valve
switches the communicating state and the shutoff state of the drain
oil passage, the pair of first oil passages can be deaerated
reliably and rapidly as much as possible.
[0029] Furthermore, according to the configuration, even if the oil
pressure is increased in the space when the rotary valve is
positioned at the communication position so that the pressure oil
in the first oil passages is discharged into the oil sump, the
pushing force produced by the oil pressure to push the rotary valve
towards the base end side of the disposing hole is canceled out by
the pushing force produced by the oil pressure to push the rotary
valve towards the distal end side of the disposing hole. Therefore,
it could be effectively prevented that the rotary valve is pushed
and moved towards the direction of exiting from the disposing hole
(i.e. the rotary valve is floated from the disposing hole) when the
rotary valve is positioned at the communication position.
[0030] In the above various configurations, the axial piston device
preferably further includes a housing surrounding the cylinder
block. The housing is configured such that an inside space thereof
is used as the oil sump.
[0031] More preferably, the housing may be configured in such a
manner as to surround the plate in addition to the cylinder block,
and the second ends of the pair of first oil passages may be
fluid-connected to conduit members supported by the housing astride
inward and outward of the housing.
[0032] Alternatively, the axial piston device may further include a
housing body having an opening formed at a first end thereof. The
housing body surrounds the cylinder block. The plate is configured
in such a manner as to be connected to the housing body so as to
close the opening formed at the first end of the housing body. In
the configuration, the housing body and the plate form the
housing.
[0033] According to the present invention, there is still provided
an axial piston device including: a rotary shaft rotating about its
axis; a cylinder block supported on the rotary shaft in a
relatively non-rotatable manner; a plurality of pistons
accommodated in the cylinder block in a slidable manner in the
axial direction; a swash plate engaging directly or indirectly free
ends of the pistons; a plate having a contact surface which is
brought into contact with discharge/suction ports of the cylinder
block, the plate being provided with a pair of first oil passages
having first ends opened to the contact surface so as to fluidly
connect with the discharge/suction ports of the cylinder block and
second ends opened to a surface of the plate, and a drain oil
passage for allowing at least one of the first oil passages to
communicate with an oil sump; and a rotary valve operated and
rotated around its axis so as to take a shutoff position at which
the drain oil passage is shut off and a communication position at
which the drain oil passage is communicated.
[0034] The pair of oil passages are substantially parallel to each
other with the rotary shaft sandwiched therebetween and extended in
a direction orthogonal to the axis of the rotary shaft.
[0035] The rotary valve is inserted in a rotatable manner around an
axis into a disposing hole formed at the plate so as to be
substantially parallel to the pair of oil passages between the pair
of oil passages.
[0036] According to the configuration, the drain oil passage could
be formed without enlarging the plate. Furthermore, both of the
pair of first oil passages could be fluidly connected to the oil
sump without a complicated oil passage structure.
BRIEF DESCRIPTION OF THE DRAWINGS
[0037] The above, and other objects, features and advantages of the
present invention will become apparent from the detailed
description thereof in conjunction with the accompanying drawings
wherein.
[0038] FIG. 1 is a longitudinal cross-sectional view showing an
axial piston unit according to a first embodiment of the present
invention.
[0039] FIG. 2 is a cross-sectional view taken along a line II-II of
FIG. 1.
[0040] FIG. 3 is a cross-sectional view taken along a line III-III
of FIG. 1.
[0041] FIG. 4 is a view as viewed from an arrow IV of FIG. 2.
[0042] FIG. 5 is a view as viewed from an arrow V of FIG. 4.
[0043] FIG. 6 is a diagram illustrating a hydraulic circuit of the
axial piston unit shown in FIGS. 1-5.
[0044] FIG. 7 is a perspective view showing a plate of the axial
piston unit shown in FIGS. 1-6, as viewed from the inner
surface.
[0045] FIG. 8 is a cross-sectional view taken along a line
VIII-VIII of FIG. 1.
[0046] FIG. 9 is a longitudinal cross-sectional view showing an
axial piston unit according to a second embodiment of the present
invention.
[0047] FIG. 10 is a cross-sectional view taken along a line X-X of
FIG. 9.
[0048] FIG. 11 is a cross-sectional view taken along a line XI-XI
of FIG. 9.
[0049] FIG. 12 is a view as viewed from an arrow XII of FIG.
10.
[0050] FIG. 13 is a cross-sectional view of a plate of a modified
axial piston unit shown in FIGS. 9-13.
[0051] FIG. 14 is a laterally partial plan view showing an axial
piston device according to a third embodiment of the present
invention.
[0052] FIG. 15 is a cross-sectional view taken along a line XV-XV
of FIG. 14.
[0053] FIG. 16 is a cross-sectional view taken along a line XVI-XVI
of FIG. 14.
[0054] FIG. 17 is a vertical cross-sectional rear view of an axial
piston device according to a fourth embodiment of the present
invention.
[0055] FIG. 18 is a cross-sectional view taken along a line
XVIII-XVIII of FIG. 17.
[0056] FIG. 19 is an enlarged view showing the section XIX in FIG.
15 in a state where a rotary valve of the axial piston device
according to the fourth embodiment is positioned at a communication
position.
[0057] FIG. 20 is a perspective view of the rotary valve of the
axial piston device according to the fourth embodiment.
[0058] FIG. 21 is a cross-sectional view showing the vicinity of a
rotary valve of an axial piston device according to a fifth
embodiment of the present invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
Embodiment 1
[0059] Hereinafter, description will be given of an axial piston
device according to a preferred embodiment of the present invention
with reference to the attached drawings.
[0060] An axial piston device according to this embodiment is used
as a pump unit, i.e., a hydraulic source with respect to hydraulic
equipment such as a hydraulic motor.
[0061] FIG. 1 is a longitudinal cross-sectional view showing a pump
unit 1 according to this embodiment. Furthermore, FIGS. 2 and 3 are
a cross-sectional view taken along a line II-II of FIG. 1 and a
cross-sectional view taken along a line III-III of FIG. 1,
respectively. Moreover, FIGS. 4 and 5 are views as viewed from an
arrow IV of FIG. 2 and an arrow V of FIG. 4, respectively.
[0062] As shown in FIGS. 1 to 3, the pump unit 1 according to this
embodiment includes a housing 10, a pump shaft 40 to be operatively
driven by a drive source (not shown), and a first pump body 50 to
be driven by the pump shaft 40.
[0063] The housing 10 is configured in such a manner as to
accommodate the first pump body 50 therein while rotatably
supporting the pump shaft about an axis.
[0064] In this embodiment, the housing 10 has a hollow housing body
20 opened at a first end thereof, and a plate 30 disposed at the
first end of the housing body 20.
[0065] Here, in this embodiment, the housing body 20 is bottomed by
closing a second end thereof.
[0066] Specifically, the housing body 20 is provided with a side
wall 21 having a positioning boss for installing a pump body, and a
circumferential wall 22 extending from the peripheral edge portion
of the side wall 21 toward a direction of the pump shaft.
[0067] The plate 30 is preferably configured in such a manner as to
liquid-tightly close an opening 20a at the first end of the housing
body 20, and therefore, an inside space 11 of the housing 10 can be
used as an oil sump.
[0068] The pump shaft 40 is rotatably supported on an axis by the
housing body 20 and the plate 30 in a state in which an input end
extends outward in such a manner as to be operatively connected to
the drive source.
[0069] In the pump shaft 40 in this embodiment, a first end 41
located upstream in a transmission direction (i.e., a right end in
FIGS. 1 and 2) extends outward of the side wall 21 of the housing
body 20, and further, a second end 42 located downstream in the
transmission direction (i.e., a left end in FIGS. 1 and 2) also
extends outward of the plate 30.
[0070] Incidentally, a second pump body 80, described later, is
supported at the second end 42 located downstream in the
transmission direction of the pump shaft 40.
[0071] The first pump body 50 is accommodated inside the housing 10
in such a state as to be freely driven by the pump shaft 40.
[0072] The first pump body 50 in this embodiment is configured in a
variable displacement type in which a suction/discharge oil rate
can be varied according to a slanting position of an output
adjusting member 53.
[0073] In particular, the first pump body 50 includes a cylinder
block 51 supported by the pump shaft 40 in a relatively
non-rotatable manner, a piston 52 slidable in the pump shaft
direction with respect to the cylinder block 51 while rotating on
the pump shaft 40 together with the cylinder block 51, and the
output adjusting member 53.
[0074] The output adjusting member 53 is provided with a movable
swash plate 54 defining a sliding range in the pump shaft direction
of the piston 52 according to a position of the piston unit 52
around the pump shaft 40, a connecting arm 55 having a first end
connected to the movable swash plate 54, and a control shaft 56
supported by the housing 10 in a rotatable manner on the axis so as
to have a first end connected to a second end of the connecting arm
55 and have a second end located outward of the housing 10.
[0075] An operating arm 61 is connected to the second end of the
control shaft 56, and thus, the control shaft 56 is rotated on the
axis by oscillating the operating arm 61 on the axis of the control
shaft 56.
[0076] As shown in FIGS. 2 to 4, the first pump body 50 in this
embodiment includes a neutral position returning mechanism 60 for
returning the movable swash plate 54 to a neutral position.
[0077] The neutral position returning mechanism 60 is provided with
the operating arm 61, a locking pin 62 disposed at a first end 61a
of the operating arm 61, a fixed pin 63 fixedly disposed at the
housing 10, and a coil spring 64 wound around the outer portion of
the control shaft 56.
[0078] A second end 61b of the operating arm 61 functions as an
operating portion. That is to say, the control shaft 56 is rotated
about its axis by oscillating the second end 61b of the operating
arm 61 about the control shaft 56, so that the movable swash plate
54 is slanted.
[0079] The coil spring 64 includes a central portion 64a wound
around the outer portion of the control shaft 56, and a first end
64b and a second end 64c extending from the central portion 64a.
The fixed pin 63 and the locking pin 62 are held between the first
end 64b and the second end 64c of the coil spring 64.
[0080] With this configuration, the fixed pin 63 is adapted to
position the movable swash plate 54 at the neutral position in a
state in which no operating force is applied to the operating arm
61 from the outside. In other words, the fixed pin 63 functions as
a neutral position setting member defining the neutral position of
the movable swash plate 54.
[0081] Particularly, when the operating arm 61 is oscillated toward
one side about the control shaft 56, the movable swash plate 54 is
oscillated in a corresponding direction according to the rotation
of the control shaft 56 about the axis, and further; the locking
pin 62 is also oscillated toward one side about the control
shaft.
[0082] When the locking pin 62 is oscillated in the above manner,
the coil spring 64 is oscillated at only the first end 64b toward
one side about the control shaft 56 in a state in which the second
end 64c is held by the fixed pin 63, whereby the coil spring 64
retains its resiliency.
[0083] Therefore, when the operating force exerted on the operating
arm 61 is released, the locking pin 62 and the operating arm 61 are
returned to the neutral position by the resiliency retained by the
coil spring 64, and accordingly, the movable swash plate 54 is
returned to the neutral position.
[0084] Preferably, the neutral position returning mechanism 60 may
be configured such that the position of the fixed pin 63 can be
adjusted relative to the axis position of the control shaft 56.
[0085] In particular, the fixed pin 63 can have an eccentric
structure. Namely, the fixed pin 63 can be configured to include a
first portion 63a, at which the position relative to the axial
position of the control shaft 56 is made invariable, and a second
portion 63b, which is eccentric from the first portion 63a and is
held between the first end 64b and the second end 64c of the coil
spring 64.
[0086] With this configuration, the position of the second portion
63b relative to the axial position of the control shaft 56 can be
readily varied by rotating the first portion 63a about the
axis.
[0087] Consequently, the position of the second portion 63b
relative to the axial position of the control shaft 56 can be
easily adjusted to a proper position corresponding to the neutral
position of the movable swash plate 54.
[0088] Although the first pump body 50 is of a variable
displacement type in this embodiment, it may be of a fixed
displacement type. If the first pump body 50 is of a fixed
displacement type, a fixed swash plate is replaced with the output
adjusting member 53.
[0089] Next, description will be given of a hydraulic circuit in
the pump unit 1 according to this embodiment.
[0090] FIG. 6 is a diagram illustrating a hydraulic circuit of the
pump unit 1 according to this embodiment.
[0091] As illustrated in FIGS. 3 and 6, the plate 30 is provided
with a pair of first oil passages 101a, 101b which have first ends
forming kidney ports so as to communicate with a discharge port 50a
and a suction port 50b of the first pump body 50, respectively, and
a drain oil passage 110 for allowing the pair of first oil passages
101a, 101b to communicate with the oil sump.
[0092] Each of the pair of first oil passages 101a, 101b has a
second end opened to the outer surface of the plate 30. The opening
ends constitute pressurized oil supplying/discharging ports 102a,
102b for communicating with a hydraulic device such as a hydraulic
motor in cooperation with the pump unit 1.
[0093] The first oil passages 101a, 101b are arranged in a
substantially linear manner substantially symmetrically with each
other in reference to the pump shaft 40 in this embodiment, as
shown in FIG. 3.
[0094] The drain oil passage 110 has a first end communicating with
at least one of the first oil passages 101a, 101b, and a second end
communicating with the oil sump.
[0095] In this embodiment, the drain oil passage 110 includes a
single substantially linear cross oil passage 111 for allowing the
pair of first oil passages 101a, 101b to communicate with each
other, and a connecting oil passage 112 having a first end
communicating with the cross oil passage 111 and a second end
opened to the surface of the plate 30, as shown in FIGS. 1 and
3.
[0096] As described above, in this embodiment, the inside space 11
of the housing 10 commonly serves as the oil sump. Consequently,
the second end of the connecting oil passage 112 is opened to an
inner surface facing to the housing inside space 11 of the plate
30.
[0097] Here, to the inner surface of the plate 30 is opened also
the pair of first oil passages 101a, 101b in addition to the drain
oil passage 110.
[0098] The pump unit 1 according to this embodiment adopts a
configuration below in order to prevent any interference of the
pair of first oil passages 101a, 101b and the drain oil passage 110
and to allow these oil passages to communicate with the housing
inside space 11.
[0099] FIG. 7 is a perspective view showing the plate 30, as viewed
from the inner surface.
[0100] As shown in FIGS. 1, 2 and 7, the pump unit 1 according to
this embodiment includes a valve plate 70 interposed between the
plate 30 and the first pump body 50.
[0101] The valve plate 70 is configured such that it can rotatably
support the cylinder block 51, and further, that it allows the
discharge port 50a and the suction port 50b of the first pump body
50 to communicate with the first ends of the first oil passages
101a, 101b, respectively.
[0102] At the inner surface of the plate 30, a groove 113 is formed
in such a manner as to be opened toward the valve plate 70. The
groove 113 extends outward in a radial direction beyond the valve
plate 70 in reference to the pump shaft 40.
[0103] With this configuration, the second end of the connecting
oil passage 112 is opened to the groove 113.
[0104] Namely, in this embodiment, the drain oil passage 110 also
includes the groove 113 in addition to the cross oil passage 111
and the connecting oil passage 112.
[0105] Most part of the groove 113 except for an outer end in a
radial direction is designed to be closed by the back surface of
the valve body 70 (i.e., a surface in contact with the plate 30)
when the valve plate 70 is disposed at the inner surface of the
plate 30. As a consequence, a simple structure can allow the drain
oil passage 110 to communicate with the oil sump, i.e., the housing
inside space 11 without exerting any adverse influence on the oil
supplying/discharging function of the cylinder block 51 while
preventing the interference with the pair of oil passages 101a,
101b and the drain oil passage 110.
[0106] As shown in FIGS. 1 and 3, a disposing hole 120, which has a
first end opened to the outer surface of the plate 30 and a second
end communicating with the drain oil passage 110, is formed at the
plate 30 in addition to the above-described various oil
passages.
[0107] Furthermore, a rotary valve 130 is inserted into the
disposing hole 120 in a rotatable manner about its axis in the
state in which the outer end extends outward of the plate 30.
[0108] The rotary valve 130 shuts off the drain oil passage 110
when it is located at a predetermined shutoff position about the
axis with respect to the disposing hole 120 (see FIG. 3); in
contrast, it allows the communication of the drain oil passage 110
when it is located at a communication position at which it is
rotated about the axis by a predetermined angle from the shutoff
position.
[0109] In other words, the rotary valve 130 is switchably operated
between the shutoff position and the communication position
according to the position about the axis with respect to the
disposing hole 120.
[0110] Incidentally, in this embodiment, the shutoff position and
the communication position can be selectively switched by rotating
the rotary valve 130 at 90.degree. about the axis.
[0111] Moreover, in this embodiment, the rotary valve 130 includes
a detent mechanism 130a which holds the rotary valve 130 at the
shutoff position and the communication position.
[0112] That is to say, a seal cap 131 coaxial with the disposing
hole 120 is screwed at the disposing hole 120 opened to one side
end face of the plate 30, and an operating shaft 132 of the rotary
valve 130 projects outward of the seal cap 131 and is provided with
a handle 133.
[0113] Additionally, at the outer edge of the handle 133 are formed
two projections 133a, 133b having the same shape as each other at
an interval of 90.degree. in a circumferential direction, as shown
in FIG. 5.
[0114] Furthermore, a positioning plate 134 having a substantial
L-shape as viewed in cross section is disposed at the one side end
face of the plate 30. The positioning plate 134 includes a lateral
plate portion in contact with the one side end face of the plate 30
and a vertical plate portion extending from the lateral plate
portion along the axial direction of the rotary valve 130. At the
vertical plate portion is formed a recess 134a into which the
projection 133a or 133b can be fitted.
[0115] The detent mechanism 130a is configured in the
above-described manner. Therefore, the projection 133a is fitted
into the recess 134a when the rotary valve 130 is located at the
shutoff position, so that the handle 133 is held at that position;
in contrast, the projection 133b is fitted into the recess 134a
when the rotary valve 130 is located at the communication position,
so that the handle 133 is held at that position.
[0116] In the pump unit 1 having this configuration, the pair of
first oil passages 101a, 101b can be remarkably speedily and
readily deaerated in comparison with the conventional pump
unit.
[0117] In the prior art in which the shutoff and communication of
the drain oil passage are switched by moving the shutoff valve
screwed into the plate in the axial direction, a communication
opening width of the drain oil passage cannot be sufficiently
secured unless the shutoff valve is rotated about the axis several
times.
[0118] Furthermore, with this conventional configuration, the valve
seat is required to be disposed at a deep portion of the oil
passage into which the shutoff valve is screwed.
[0119] In contrast, in the pump unit 1 according to this
embodiment, the shutoff and communication of the drain oil passage
110 can be switched without rotating the rotary valve 130 once
about the axis (only by rotation at 90.degree. in this embodiment),
and thus, the pair of first oil passages 101a, 101b can be
remarkably speedily deaerated.
[0120] Furthermore, in this embodiment, no valve seat is required
to be disposed, unlike the prior art, and therefore, the drain oil
passage 110 can be readily bored.
[0121] Moreover, in the pump unit 1 according to this embodiment, a
charge oil passage 140 for supplying charge oil to the pair of
first oil passages 101a, 101b is formed at the plate 30, as
illustrated in FIGS. 3 and 6.
[0122] The charge oil passage 140 includes a first bypass oil
passage 141 for allowing the pair of first oil passages 101a, 101b
to communicate with each other, and a suction oil passage 142 which
has a first end connected to the first bypass oil passage 141 and a
second end communicating with the housing inside space 11.
[0123] Check valves 150a, 150b for allowing an oil flow from the
suction oil passage 142 to the pair of first oil passages 101a,
101b and preventing a reverse oil flow are interposed between a
connecting point of the first bypass oil passage 141 to the suction
oil passage 142 and the pair of first oil passages 101a, 101b,
respectively.
[0124] In this embodiment, a throttle 155 is disposed in the check
valve 150b interposed between the first oil passage 101b of the
first oil passages 101a, 101b and the charge oil passage 140,
thereby increasing a neutral width of the first pump body 50.
[0125] Additionally, a self-sucking throttle 145 in the case where
either one of the first oil passages 101a, 101b becomes low in
pressure due to oil leakage is provided on the charge oil passage
140. The inside of each of the first oil passages 101a, 101b can be
kept in a state full of oil all the time by providing the throttle
145. As a consequence, in the case where the pump unit 1 according
to the present invention is used as, for example, a drive source
for a vehicle traveling hydraulic motor, there is no danger that a
vehicle cannot be rolled down toward a ravine even if the vehicle
is parked on a slope without applying parking brake.
[0126] Here, in this embodiment, the second end of the suction oil
passage 142 is opened to the groove 113. As described above, most
part of the groove 113 except for the outer end in the radial
direction is closed by the valve plate 70. As a consequence, the
simple structure can allow the suction oil passage 142 to
communicate with the housing inside space 11 without exerting any
adverse influence on the oil supplying/discharging function of the
cylinder block 51 while preventing the interference with the pair
of first oil passages 101a, 101b and the drain oil passage 110.
[0127] In addition to the above configurations, the pump unit 1
according to this embodiment includes the second pump body 80 to be
driven by the pump shaft 40, and a pair of second oil passages
201a, 201b communicating with a discharge port 80a and a suction
port 80b of the second pump body 80, respectively.
[0128] The second pump body 80 is adapted to supply pressurized oil
to the hydraulic device in cooperation with the first pump body 50
or another hydraulic device other than the hydraulic device.
[0129] In this embodiment, the second pump body 80 is supported at
the second end 42 downstream in the transmission direction of the
pump shaft 40 (i.e., the left end in FIGS. 1 and 2).
[0130] FIG. 8 is a cross-sectional view taken along a line
VIII-VIII of FIG. 1.
[0131] As shown in FIGS. 1 to 8, the pair of second oil passages
201a, 201b is bored in a pump case 90 surrounding the second pump
body 80.
[0132] That is to say, the pump unit 1 according to this embodiment
includes the pump case 90 connected to an outer surface on a side
opposite to the inner surface of the plate 30 in such a manner as
to surround the second pump body 80. The pair of second oil
passages 201a, 201b is formed in the pump case 90.
[0133] In particular, the second oil passages 201a, 201b have first
ends communicated with the discharge port 80a and the suction port
80b of the second pump body 80, respectively, second ends opened to
the surface of the pump case 90, thereby forming a discharge port
202a and a suction port 202b, respectively.
[0134] As shown in FIGS. 6 and 8, a relief valve 210 for setting an
operating oil pressure for the hydraulic device in cooperation with
the second pump body 80 is inserted into the positive pressure oil
passage 201a communicating with the discharge port 80a of the
second pump body 80 out of the pair of second oil passages 201a,
201b.
[0135] In this embodiment, a bypass oil passage 220 for allowing
the second oil passages 201a, 201b to communicate with each other
is formed in the pump case 90, and thus, the relief valve 210 is
inserted into the bypass oil passage 220.
[0136] In contrast, the negative pressure oil passage 201b
communicating with the suction port 80b in the second pump body 80
out of the pair of second oil passages 201a, 201b is connected to
the pair of first oil passages 101a, 101b.
[0137] Namely, at least a part of the oil, which is supplied from
the discharge port 80a of the second pump body 80 to the hydraulic
device via one of the second oil passages (i.e., the positive
pressure oil passage 201a) and is returned to the suction port 80b
of the second pump body 80 via the other one of the second oil
passages (i.e., the negative pressure oil passage 201b), is
designed to be introduced to the pair of first oil passages 101a,
101b, thereby speedily deaerating the pair of second oil passages
201a, 201b by use of the rotary valve 130.
[0138] In this embodiment, the plate 30 includes a first connecting
oil passage 231 which has a first end communicating with the charge
oil passage 140 and a second end opened to the surface in contact
with the pump case 90, as shown in FIG. 1.
[0139] Furthermore, the pump case 90 is provided with a second
connecting oil passage 232 which has a first end communicating with
the negative pressure oil passage 201b and a second end opened to
the surface in contact with the plate 30, so as to communicate with
the first connecting oil passage 231.
[0140] In other words, the negative pressure oil passage 201b is
designed to communicate with the pair of first oil passages 101a,
101b via the second connecting oil passage 232, the first
connecting oil passage 231 and the charge oil passage 140.
[0141] Moreover, a charge relief valve 240 for setting an oil
pressure of the pressurized oil flowing to the charge oil passage
140 from the negative pressure oil passage 201b is inserted into
the negative pressure oil passage 201b.
[0142] Additionally, in the pump case 90 is formed a suction oil
passage 250 which has a first end opened to the surface so as to
form a suction port 250a and a second end communicating with the
negative pressure oil passage 201b.
[0143] Incidentally, reference numeral 260 in FIG. 1 designates a
drain port for draining the oil reserved inside the housing inside
space 11.
[0144] In addition, reference numeral 270 in FIG. 6 designates a
leak oil passage from the first pump body 50 to the oil sump (i.e.,
the housing inside space 11 in this embodiment).
Embodiment 2
[0145] Hereinafter, description will be given of an axial piston
device according to another preferred embodiment of the present
invention with reference to the attached drawings.
[0146] An axial piston device 1B according to this embodiment is
also configured to be used as a pump unit in the same manner as in
the first embodiment.
[0147] FIG. 9 is a longitudinal cross-sectional view showing the
pump unit 1B according to this embodiment. Furthermore, FIGS. 10
and 11 are a cross-sectional view taken along a line X-X of FIG. 9
and a cross-sectional view taken along a line XI-XI of FIG. 9,
respectively. Moreover, FIG. 12 is a view as viewed from an arrow
XII of FIG. 10.
[0148] Here, in FIGS. 9 to 12, the same or corresponding components
as or to those in the first embodiment are designated by the same
reference numerals; therefore, the detailed description for those
components will not be given herein.
[0149] The pump unit 1B according to this embodiment is configured
in substantially the same manner as that in the first embodiment
except that the movable swash plate 54 in the pump unit 1 in the
first embodiment is replaced with a trunnion-type movable swash
plate 54B and that the seat faces of the check valves 150a, 150b
are constituted of components independent of the plate 30.
[0150] In particular, the pump unit 1B includes the trunnion-type
movable swash plate 54B in place of the movable swash plate 54, as
shown in FIGS. 9 and 10.
[0151] The above-described movable swash plate 54B of a trunnion
type has small sliding resistance, so that the movable swash plate
54B can be speedily returned to a neutral position of the movable
swash plate 54B by means of the neutral position returning
mechanism 60.
[0152] Furthermore, the pump unit 1B includes a pair of seat
members 151 to be inserted into the first bypass oil passage
141.
[0153] More particularly, the first bypass oil passage 141 includes
a small-diameter portion 143 communicating with the suction oil
passage 142 and a pair of large-diameter portions 144 whose
diameter is enlarged with steps continuous from the small-diameter
portion 143 and which communicates with the pair of first oil
passages 101a, 101b, respectively, as shown in FIG. 11.
[0154] The pair of seat members 151 are disposed inside the
large-diameter portions 144, respectively, so that each seat face
155 is oriented toward the corresponding first oil passages 101a,
101b.
[0155] Incidentally, the seat member 151 is fixed to the
large-diameter portion 144 by, for example, a stopper ring (see
FIG. 11) or press-fitting.
[0156] In this manner, a repairing work in the case of degradation
of the seat face 155 can be readily performed at low cost by
forming the seat face 155 of a member independent of the plate 30
(the seat member 151 in this embodiment).
[0157] In a situation in which the first pump body 50 is operated
for a long period of time in the state of, for example, application
of a high load, the check valves 150a, 150b are frequently opened
and closed, whereby the seat face 155 is abraded, thereby inducing
a possibility of leakage of operating oil from the pair of first
oil passages 101a, 101b.
[0158] Especially in the case where the plate 30 is made of
aluminum, the possibility of leakage is tended to become
stronger.
[0159] In such a case, the seat face 155 can be repaired by only
replacing the seat member 151, if the seat face 155 is formed of a
member independent of the plate 30, like in this embodiment.
[0160] FIG. 13 is a cross-sectional view showing the plate 30
provided with cartridge-type check valves 152a, 152b.
[0161] As described above, the seat member 151 provided with the
seat face 155 is used in this embodiment. Alternatively, there may
be provided the cartridge-type check valves 152a, 152b each
including a valve case having a seat face 155, as shown in FIG.
13.
Embodiment 3
[0162] Hereinafter, description will be given of an axial piston
device according to still another preferred embodiment of the
present invention with reference to the attached drawings.
[0163] FIG. 14 is a laterally partial plan view showing an axial
piston device 1C according to this embodiment. Furthermore, FIGS.
15 and 16 are a cross-sectional view taken along a line XV-XV of
FIG. 14 and a cross-sectional view taken along a line XVI-XVI of
FIG. 14, respectively.
[0164] The axial piston device 1C according to this embodiment is
configured to be used as a motor unit, unlike the first and second
embodiments.
[0165] In other words, each of the axial piston devices 1, 1B
according to the first and second embodiments includes the pump
shaft 40 as the rotary shaft and the pump body 50 serving as the
rotor rotatable together with the rotary shaft; in contrast, the
axial piston device 1C according to this embodiment includes a
motor shaft 340 as the rotary shaft and a motor body 350 serving as
the rotor.
[0166] Specifically, the axial piston device 1C comprises the motor
shaft 340, the motor body 350 including a cylinder block 351 fitted
around in a non-rotatable manner relative to the motor shaft 340
and a plate 330 which is brought into contact with a discharge port
and a suction port in the motor body 350. The motor block 351 is
configured in such a manner as to be rotated with the application
of an oil pressure from an oil source such as a hydraulic pump unit
which is liquid-connected via the plate 330, thereby outputting
rotational drive force from the motor shaft 340.
[0167] The axial piston device 1C according to this embodiment
further comprises a housing 320 surrounding the motor body 350 and
the plate 330, wherein its inside space serves as an oil sump.
[0168] As shown in FIGS. 14 to 16, an axle case for supporting a
pair of drive axle shafts 400 for driving a pair of drive wheels is
commonly used as the housing 320 in this embodiment.
[0169] That is to say, the axle case 320 includes first and second
case bodies 321, 322 which are detachably connected to each other,
so that a liquid-tight inside space can be defined by connecting
the first and second case bodies 321, 322.
[0170] More particularly, the inside space of the axle case 320 is
divided into a motor unit accommodating space 320a for
accommodating therein the motor body 350 and the plate 330, a
deceleration gear train accommodating space 320b for accommodating
therein a deceleration gear train 410 operatively connected to the
motor shaft 340, a differential gear unit accommodating space 320c
for accommodating therein a differential gear unit 420 operatively
connected to the deceleration gear train 410, and a drive axle
shaft accommodating space 320d for accommodating therein a pair of
drive axle shafts 400 operatively connected to the differential
gear unit 420.
[0171] Incidentally, reference numeral 430 in FIG. 14 designates a
brake mechanism capable of applying brake force to the motor shaft
340.
[0172] The motor shaft 340 has a base end supported by the plate
330 and a tip end supported on a partition wall of the axle case
320 in such a manner as to be exposed to the deceleration gear
train accommodating space 320b.
[0173] The motor body 350 includes the cylinder block 351 fitted
around in a non-rotatable manner relative to the motor shaft 340, a
piston 352 accommodated inside the cylinder block 351 in a freely
advancing/retreating manner in an axial direction, and a swash
plate 354 defining an advancing/retreating range in the axial
direction of the piston 352.
[0174] Here, the axial piston device 1C according to this
embodiment is of a variable displacement type.
[0175] Consequently, the motor body 350 includes a movable swash
plate serving as the swash plate 354. Furthermore, the motor body
350 includes a connecting arm 355 having a first end connected to
the movable swash plate 354, and a control shaft 356 supported by
the housing 320 in a rotatable manner about an axis so as to have a
first end connected to a second end of the connecting arm 355 and a
second end positioned outward of the housing 320.
[0176] As shown in FIG. 15, at the plate 330 are disposed a pair of
oil passages 301a, 301b having first ends communicating with a
discharge port and a suction port of the motor body 350,
respectively, and a drain oil passage 310 for allowing the pair of
oil passages 301a, 301b to communicate with the oil sump.
[0177] More particularly, as shown in FIG. 14, each first end of
the pair of oil passages 301a, 301b is opened to a contact surface
331 in contact with the motor body in outer surface of the plate
330.
[0178] Furthermore, each second end of the pair of oil passages
301a, 301b is opened to a back surface 332 on a side opposite to
the contact surface 331.
[0179] As described above, the plate 330 is also surrounded by the
housing 320 in this embodiment.
[0180] As a consequence, each second end of the pair of oil
passages 301a, 301b is fluid-connected to a hydraulic source such
as a hydraulic pump via a conduit member 305 supported by the
housing 320 astride inward and outward of the housing 320 (see
FIGS. 14 and 16).
[0181] The drain oil passage 310 has a first end communicating with
at least one of the oil passages 301a, 301b, and a second end
communicating with the oil sump (i.e., the inside space of the
housing 320 in this embodiment).
[0182] According to this embodiment, the drain oil passage 310
includes a single cross oil passage 311 of a substantially linear
shape for allowing the pair of oil passages 301a, 301b to
communicate with each other, and a connecting oil passage 312
having a first end communicating with the cross oil passage 311 and
a second end opened to the back surface 332 of the plate 330, as
shown in FIGS. 14 to 16.
[0183] Moreover, a disposing hole 120 is bored at the plate 330,
like in the first and second embodiments and, further, a rotary
valve 130 is inserted into the disposing hole 120 in a rotatable
manner about an axis.
[0184] Incidentally, according to this embodiment, the outer end of
the rotary valve 130 extends outward of the housing 320 (i.e., the
axle case) such that the rotary valve 130 can be operated outward
of the housing 320.
[0185] Additionally, a handle 133 is attached to an outward
extending portion 132 at the rotary valve 130, like in the first
and second embodiments.
[0186] As shown in FIGS. 15 and 16, a projection 133a is formed at
the handle 133.
[0187] An engaging recess 134a formed is integrally with the
housing 320. The projection 133a and the engaging recess 134a
constitute a detent mechanism 130a for holding the rotary valve 130
at cutoff/communication positions.
Embodiment 4
[0188] Hereinafter, description will be given of an axial piston
device according to still another preferred embodiment of the
present invention with reference to the attached drawings.
[0189] FIG. 17 is a vertical cross-sectional rear view of an axial
piston device 1D according to this embodiment. Furthermore, FIG. 18
is a cross-sectional view taken along a line XVIII-XVIII of FIG.
17.
[0190] The same or corresponding components as or to those in each
of the above embodiments are designated by the same reference
numerals; therefore, the detailed description for those components
will not be given herein.
[0191] The axial piston device 1D according to this embodiment has
a drain structure of a configuration different from each of the
above embodiments.
[0192] An example in which the drain structure is applied to the
motor unit is described in this embodiment, but the drain structure
may obviously be applied to the pump unit.
[0193] In the drain structure according to each of the above
embodiments, the rotary valve 130 may be sometimes pushed and moved
into a direction of exiting from the disposing hole 120 by the
pressure oil flowing from the pair of oil passages 101a, 101b
(301a, 301b) to the oil sump when communicating the corresponding
pair of oil passages 101a, 101b (301a, 301b) to the oil sump.
[0194] The drain structure according to this embodiment effectively
prevents such disadvantages.
[0195] The drain structure according to each of the above
embodiments will first be described.
[0196] FIG. 19 is an enlarged view showing the section XIX in FIG.
15 in a state where the rotary valve 130 is positioned at a
communication position.
[0197] As shown in FIG. 19, the drain oil passage 310 includes an
upstream-side drain oil passage 311 fluidly connected to at least
one of the pair of oil passages 301a, 301b, a downstream-side drain
oil passage 312 fluidly connected to the oil sump (internal space
of the housing 320 in the illustrated embodiment), and the
disposing hole 120 that crosses both the upstream-side drain oil
passage 311 and the downstream-side drain oil passage 312 and that
has a base end opened to the outer surface of the plate.
[0198] In the illustrated embodiment, the upstream-side drain oil
passage 311 is fluidly connected to both of the pair of oil
passages 301a, 301b. That is, the upstream-side drain oil passage
311 includes a first upstream-side drain oil passage 311a fluidly
connected to one of the pair of oil passages 301a, and a second
upstream-side drain passage 311b fluidly connected to the other one
of the pair of oil passages 301b.
[0199] The rotary valve 130 is inserted into the disposing hole
120, as described above.
[0200] Specifically, the rotary valve 130 is inserted into the
disposing hole 120 with a gap 121 formed between the distal end
face of the rotary valve 130 and the distal end of the disposing
hole 120.
[0201] The downstream-side drain oil passage 312 has a first end
fluidly connected to the oil sump and a second end opened to the
gap 121.
[0202] The rotary valve 130 has an outer peripheral surface that
liquid tightly contacts the inner peripheral surface of the
disposing hole 120 at an upstream-side connecting point 311T where
the upstream-side drain oil passage 311 and the disposing hole 120
intersect.
[0203] Furthermore, the rotary valve 130 is formed with a
communication oil passage 135 that causes the drain oil passage 310
to be in the communicating state when the rotary valve 130 is
positioned at the communication position and the drain oil passage
310 to be in the shutoff state when the rotary valve 130 is
positioned at the shutoff position.
[0204] As shown in FIG. 19, the communication oil passage 135 has a
first end opened to the outer peripheral surface and a second end
opened to the distal end face so as to be fluidly connected to the
gap 121.
[0205] Specifically, the first end of the communication oil passage
135 is opened to the outer peripheral surface of the rotary valve
130 at a circumferential position so as to be fluidly shutoff with
respect to the upstream-side drain oil passage 311 when the rotary
valve 130 is positioned at the shutoff position, and fluidly
connected to the upstream-side drain oil passage 311 when the
rotary valve 130 is positioned at the communication position.
[0206] In this embodiment, the upstream-side drain oil passage 311
includes the first and second upstream-side drain oil passages
311a, 311b, as described above.
[0207] Therefore, the first end of the communication oil passage
135 is branched into two ends so that both the first and second
upstream-side drain oil passages 311a, 311b are fluidly connected
to the communication oil passage 135 when the rotary valve 130 is
positioned at the communication position.
[0208] The rotary valve 130 operates in the following manner.
[0209] That is, when positioning the rotary valve 130 at the
shutoff position (see FIG. 15), the upstream-side drain oil passage
311 is shutoff with respect to the disposing hole 120 by the outer
peripheral surface of the rotary valve 130, and therefore the oil
passages 301a, 301b are maintained in a closed circuit.
[0210] In contrast, when positioning the rotary valve 130 at the
communication position (see FIG. 19), the upstream-side drain oil
passage 311 is fluidly connected to the oil sump by way of the
communication oil passage 135, the gap 121 and the downstream-side
drain oil passage 312. Therefore, the pressure oil in the oil
passages 301a, 301b is discharged into the oil sump.
[0211] However, in the rotary valve 130, the communication oil
passage 135 is fluidly connected to the downstream-side drain oil
passage by way of the gap 121, as described above.
[0212] In the configuration, the oil pressure is produced in the
gap 121 when the rotary valve 130 is positioned at the
communication position and the pressure oil in the oil passages
301a, 301b is discharged into the oil sump. The oil pressure pushes
the rotary valve 130 into the direction L of exiting from the
disposing hole 120.
[0213] Therefore, in the rotary valve 130 according to each of the
above embodiments, the rotary valve 130 floats from the disposing
hole 120 by the oil pressure produced in the gap 121, whereby
disadvantages may occur such that the pressure oil is inhibited
from flowing from the upstream-side drain oil passage 311 into the
communication oil passage 135, and the detent mechanism 130a is
more likely to disengage the rotary valve 130.
[0214] In view of the above points, the axial piston device 1D
according to this embodiment has a drain structure of the following
configuration.
[0215] That is, the axial piston device 1D according to this
embodiment includes a rotary valve 130D in place of the rotary
valve 130 in the axial piston device 1C according to embodiment 3,
as shown in FIGS. 17 and 18.
[0216] Specifically, the axial piston device 1D includes the rotary
shaft 340 rotating about its axis; the cylinder block 351 mounted
on the rotary shaft 340 in a relatively non-rotatable manner; the
plurality of pistons 352 accommodated in the cylinder block 351 in
a slidable manner along the axial direction of the rotary shaft
340; the swash plate 354 for directly or indirectly engaging the
free end of the plurality of pistons 352 so as to define a sliding
range of the piston 352; the plate 330 having a contact surface 331
which is brought into contact with the discharge port and the
suction port of the cylinder block 351; and the rotary valve
130D.
[0217] Components other than the rotary valve 130D are the same as
the components in the above embodiments. Therefore, the detailed
explanation thereof is not repeated here.
[0218] FIG. 20 is a perspective view of the rotary valve 130D.
[0219] As shown in FIGS. 17, 18, and 20, the rotary valve 130D
includes a main body 136D having an outer peripheral surface that
liquid tightly contacts the inner peripheral surface of the
disposing hole 120 at the upstream-side connecting point 311T where
the upstream-side drain oil passage 311 and the disposing hole 120
intersect; a small-diameter portion 137D that is contracted with a
step 136D' from the main body 136D and that is extended towards the
distal end side of the disposing hole 120 from the main body 136D,
the small-diameter portion 137D defining a space S between the
inner peripheral surface of the disposing hole 120 and the outer
peripheral surface of the small-diameter portion 137D; a flange
portion 138D that is enlarged from the small-diameter portion 137D
with a step 138D' and is positioned at the distal end side of the
disposing hole 120 from the downstream-side connecting point 312T
where the downstream-side drain oil passage 312 and the disposing
hole 120 intersect, the flange portion 138D having an outer
peripheral surface that liquid tightly contacts the inner
peripheral surface of the disposing hole 120; and a communication
groove 139D formed on the outer peripheral surface of the main body
136D so as to extend from the position in the axial direction
corresponding to the upstream-side connecting point 311T to the
space S.
[0220] The base end of the main body 136D extends outward as shown
in FIG. 17, and forms the operating shaft 132 that is externally
operable.
[0221] The communication groove 139D is formed at the position in
the circumferential direction so as to be fluidly shutoff with
respect to the upstream-side drain oil passage 311 when the rotary
valve 130D is positioned at the shutoff position, and fluidly
connected to the upstream-side drain oil passage 311 when the
rotary valve 130D is positioned at the communication position.
[0222] In this embodiment, the upstream-side drain oil passage 311
includes the first and second upstream-side drain oil passages
311a, 311b, as shown in FIG. 18.
[0223] Therefore, the communication groove 139D includes a first
communication groove 139Da and a second communication groove 139Db
respectively fluidly connected to the first and second
upstream-side drain oil passages 311a, 311b, when the rotary valve
130D is positioned at the communication position.
[0224] The rotary valve 130D operates in the following manner.
[0225] That is, when positioning the rotary valve 130D at the
shutoff position, the upstream-side drain oil passage 311 is
shutoff with respect to the disposing hole 120 by the outer
peripheral surface of the rotary valve 130D, and therefore the oil
passages 301a, 301b are maintained in a closed circuit.
[0226] In contrast, when positioning the rotary valve 130D at the
communication position, the upstream-side drain oil passage 311 is
fluidly connected to the oil sump by way of the communication
groove 139D, the space S, and the downstream-side drain oil passage
312, and the pressure oil in the oil passages 301a, 301b is
discharged into the oil sump.
[0227] When positioning the rotary valve 130D at the communication
position, the oil pressure is produced in the space S. While the
oil pressure acts on the step 136D' between the main body 136D and
the small-diameter portion 137D to push the rotary valve 130D into
a direction of exiting from the disposing hole 120, it acts on the
step 138D' between the small-diameter portion 137D and the flange
portion 138D to push the rotary valve 130D towards the distal end
side of the disposing hole 120.
[0228] That is, in the axial piston device 1D according to this
embodiment, even if the oil pressure is increased in the space S
when the rotary valve 130D is positioned at the communication
position so that the pressure oil in the oil passages 301a, 301b is
discharged into the oil sump, the pushing force produced by the oil
pressure to push the rotary valve 130D towards the base end side of
the disposing hole 120 is canceled out by the pushing force
produced by the oil pressure to push the rotary valve 130D towards
the distal end side of the disposing hole 120.
[0229] Therefore, in this embodiment, the disadvantage of the
rotary valve 130D floating from the disposing hole 120 when
positioned at the communication position is prevented, and thus the
disadvantages such as the detent mechanism 130a being more likely
to disengage the rotary valve 130D.
Embodiment 5
[0230] Hereinafter, description will be given of an axial piston
device according to still another preferred embodiment of the
present invention with reference to the attached drawings.
[0231] FIG. 21 is a cross-sectional view showing the vicinity of
the rotary valve in an axial piston device 1E according to this
embodiment.
[0232] The same or corresponding components as or to those in each
of the above embodiments are designated by the same reference
numerals; therefore, the detailed description for those components
will not be given herein.
[0233] Similar to the axial piston device 1D according to
embodiment 4, the axial piston device 1E according to this
embodiment has a drain structure configured so that the rotary
valve 130E is effectively prevented from being pushed and moved
into the direction of exiting from the disposing hole 120.
[0234] An example in which the drain structure is applied to the
motor unit is described in this embodiment, but the drain structure
may obviously be applied to the pump unit.
[0235] The axial piston device 1E according to this embodiment
includes a rotary valve 130E in place of the rotary valve 130D in
the axial piston device according to embodiment 4, as shown in FIG.
21.
[0236] As shown in FIG. 21, the rotary valve 130E includes a main
body 136E having an outer peripheral surface that liquid tightly
contacts the inner peripheral surface of the disposing hole 120 at
the upstream-side connecting point 311T where the upstream-side
drain oil passage 311 and the disposing hole 120 intersect and at
the downstream-side connecting point 312T where the downstream-side
drain oil passage 312 and the disposing hole 120 intersect; and a
communication oil passage 135E formed at the main body 136E so as
to have a first end and a second end respectively opened to the
outer peripheral surface at the positions in the axial direction
respectively corresponding to the upstream-side connecting point
311T and the downstream-side connecting point 312T.
[0237] Specifically, The first end of the communication oil passage
135E is opened to the outer peripheral surface at the position in
the circumferential direction so as to be fluidly shutoff with
respect to the upstream-side drain oil passage 311 when the rotary
valve 130E is positioned at the shutoff position and fluidly
connected to the upstream-side drain oil passage 311 when the
rotary valve 130E is positioned at the communication position.
[0238] The second end of the communication oil passage 135E is
opened to the outer peripheral surface at the position in the
circumferential direction so as to be fluidly connected to the
downstream-side drain oil passage 312 when the rotary valve 130E is
positioned at the communication position.
[0239] In the axial piston device 1E having the drain structure of
the above configuration, the rotary valve 130E is effectively
prevented from being pushed and moved into a direction of exiting
from the disposing hole 120 (i.e., rotary valve 130E is prevented
from floating from the disposing hole 120) by the pressure oil when
the rotary valve 130E is positioned at the communication position
so that the pressure oil in the oil passages 301a, 301b is
discharged into the oil sump.
[0240] Similar to embodiment 4, the upstream-side drain oil passage
311 includes the first and second upstream-side drain oil passages
311a, 311b in this embodiment.
[0241] Therefore, the first end of the communication oil passage
135E is branched into two ends so that both the first and second
upstream-side drain oil passages 311a, 311b are fluidly connected
to the communication oil passage 135E when the rotary valve 130E is
positioned at the communication position.
[0242] In each of the above embodiments, the pair of oil passages
101a, 101b (301a, 301b) are substantially parallel to each other
with the corresponding rotary shaft 40 (340) inbetween and are
extended in a direction orthogonal to the axis of the rotary shaft
40 (340).
[0243] The disposing hole 120 is formed so as to be substantially
parallel to the pair of oil passages 101a, 101b (301a, 301b)
between the pair of oil passages 101a, 101b (301a, 301b), whereby
both of the pair of oil passages 101a, 101b (301a, 301b) are
fluidly connected to the oil sump by way of the rotary valve 130
(130D, 130E) without forming a complicated oil passage
structure.
[0244] Therefore, deaeration of the oil passage is reliably and
rapidly performed, while the oil passage structure for performing
deaeration is simplified.
[0245] This specification is by no means intended to restrict the
present invention to the preferred embodiments set forth therein.
Various modifications to the axial piston device may be made by
those skilled in the art without departing from the spirit and
scope of the present invention as defined in the appended
claims.
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