U.S. patent application number 14/389319 was filed with the patent office on 2015-03-05 for fluid pressure drive unit.
This patent application is currently assigned to KAYABA INDUSTRY CO., LTD.. The applicant listed for this patent is KAYABA INDUSTRY CO., LTD.. Invention is credited to Kazunari Suzuki, Shinji Yakabe.
Application Number | 20150064030 14/389319 |
Document ID | / |
Family ID | 49259831 |
Filed Date | 2015-03-05 |
United States Patent
Application |
20150064030 |
Kind Code |
A1 |
Suzuki; Kazunari ; et
al. |
March 5, 2015 |
FLUID PRESSURE DRIVE UNIT
Abstract
A fluid pressure drive unit is to supply a working fluid to and
drive a fluid pressure actuator. The fluid pressure drive unit
includes a fluid pressure pump for suctioning and discharging the
working fluid, an electric motor for driving and rotating the fluid
pressure pump, a power transmission mechanism for transmitting a
power between a rotation shaft of the fluid pressure pump and a
rotation shaft of the electric motor, and a circulation mechanism
to be driven by the power transmitted by the power transmission
mechanism, the circulation mechanism for guiding a lubricating
fluid in the power transmission mechanism and cooling the electric
motor.
Inventors: |
Suzuki; Kazunari; (Kanagawa,
JP) ; Yakabe; Shinji; (Tokyo, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
KAYABA INDUSTRY CO., LTD. |
Tokyo |
|
JP |
|
|
Assignee: |
KAYABA INDUSTRY CO., LTD.
Tokyo
JP
|
Family ID: |
49259831 |
Appl. No.: |
14/389319 |
Filed: |
March 22, 2013 |
PCT Filed: |
March 22, 2013 |
PCT NO: |
PCT/JP2013/058254 |
371 Date: |
September 29, 2014 |
Current U.S.
Class: |
417/372 |
Current CPC
Class: |
F03C 1/0636 20130101;
F04B 53/08 20130101; F03C 1/0644 20130101; F04B 17/03 20130101;
F04B 53/18 20130101 |
Class at
Publication: |
417/372 |
International
Class: |
F04B 53/18 20060101
F04B053/18; F04B 53/08 20060101 F04B053/08; F04B 17/03 20060101
F04B017/03 |
Foreign Application Data
Date |
Code |
Application Number |
Mar 29, 2012 |
JP |
2012-075565 |
Claims
1. A fluid pressure drive unit adapted to supply a working fluid to
and driving a fluid pressure actuator, comprising: a fluid pressure
pump that is configured to suction and discharge the working fluid;
an electric motor that is configured to drive and rotate the fluid
pressure pump; a power transmission mechanism that is configured to
transmit a power between a rotation shaft of the fluid pressure
pump and a rotation shaft of the electric motor; and a circulation
mechanism that is configured to be driven by the power transmitted
by the power transmission mechanism, the circulation mechanism that
is configured to guide a lubricating fluid in the power
transmission mechanism and cool the electric motor.
2. The fluid pressure drive unit according to claim 1, wherein the
power transmission mechanism includes a first gear that is
configured to rotate integrally with the rotation shaft of the
fluid pressure pump, a second gear that is configured to rotate
integrally with the rotation shaft of the electric motor, and an
idle gear provided between the first gear and the second gear, the
idle gear that is configured to transmit the power, and the
circulation mechanism has a rotation member that is configured to
rotate integrally with at least any one of the first gear, the
second gear, and the idle gear, the rotation member that is
configured to stir up the lubricating fluid in the power
transmission mechanism.
3. The fluid pressure drive unit according to claim 2, wherein the
circulation mechanism includes: a supply flow passage through which
the lubricating fluid stirred up by the rotation member is guided
to the electric motor; and a reflux flow passage through which the
lubricating fluid guided to the electric motor is returned into the
power transmission mechanism.
4. The fluid pressure drive unit according to claim 2, wherein the
rotation member is an impeller to be rotated integrally with the
idle gear.
5. The fluid pressure drive unit according to claim 1, further
comprising: a plate having an identical surface to which the fluid
pressure pump and the electric motor are attached, the plate
through which the rotation shaft of the fluid pressure pump and the
rotation shaft of the electric motor pass, wherein the electric
motor is arranged in parallel to the fluid pressure pump.
6. The fluid pressure drive unit according to claim 1, further
comprising: a fluid pressure motor that is configured to be driven
and rotated with the supplied working fluid, using a rotation shaft
common to the rotation shaft of the fluid pressure pump, wherein
the electric motor is capable of generating regenerative electric
power by the rotation of the fluid pressure motor.
7. The fluid pressure drive unit according to claim 6, to be
applied to a hybrid construction machine in which the fluid
pressure actuator is driven with a working fluid discharged from a
main fluid pressure pump which is driven by a motor, wherein the
fluid pressure motor is configured to be driven and rotated with
the working fluid emitted from the fluid pressure actuator, the
electric motor that is configured to generate the regenerative
electric power by the rotation of the fluid pressure motor, and is
configured to drive and rotate the fluid pressure pump by using the
regenerative electric power, and the fluid pressure pump that is
configured to assist drive of the fluid pressure actuator by the
main fluid pressure pump with the discharged working fluid.
Description
TECHNICAL FIELD
[0001] The present invention relates to a fluid pressure drive unit
for adapted to supply a working fluid to and driving a fluid
pressure actuator.
BACKGROUND ART
[0002] Conventionally, in a construction machine such as a power
shovel, a hybrid structure in which a power generator is rotated by
an extra output of an engine and emission energy of an actuator,
electric power generated by the power generator is stored, and
actuation of the actuator is assisted by using the stored electric
power is used. In such a hybrid structure, a fluid pressure drive
unit including an electric motor to be rotated with the stored
electric power, and an assist pump to be driven and rotated by the
electric motor, the assist pump for discharging a working fluid and
assisting the actuation of the actuator by a main pump is used.
[0003] JP2011-127569A discloses an assist regeneration device
including a motor generator to be actuated and rotated with
electric energy, a regeneration motor for driving and rotating the
motor generator with energy of a working fluid, and an assist pump
to be driven and rotated by the motor generator, the assist pump
for discharging the working fluid.
SUMMARY OF INVENTION
[0004] However, in the assist regeneration device of
JP2011-127569A, when being driven and rotated or when generating
the regenerative electric power, the motor generator generates
heat. Therefore, there is a need for a cooling system of
circulating a refrigerant by using a pump and cooling the motor
generator from an exterior.
[0005] The present invention is achieved in consideration with the
above problem, and an object thereof is to simplify a cooling
mechanism of an electric motor in a hydraulic pressure drive
unit.
[0006] According to one aspect of the present invention, a fluid
pressure drive unit adapted to supply a working fluid to and
driving a fluid pressure actuator is provided. The fluid pressure
drive unit includes a fluid pressure pump that is configured to
suction and discharge the working fluid, an electric motor that is
configured to drive and rotate the fluid pressure pump, a power
transmission mechanism that is configured to transmit a power
between a rotation shaft of the fluid pressure pump and a rotation
shaft of the electric motor, and a circulation mechanism that is
configured to be driven by the power transmitted by the power
transmission mechanism, the circulation mechanism that is
configured to guide a lubricating fluid in the power transmission
mechanism and cool the electric motor.
[0007] The details as well as other features and advantages of the
present invention are set forth in the remainder of the
specification and are shown in the accompanying drawings.
BRIEF DESCRIPTION OF DRAWINGS
[0008] FIG. 1 is a front view showing a part of a fluid pressure
drive unit according to an embodiment of the present invention in a
sectional view.
[0009] FIG. 2 is a sectional view by line II-II of a fluid pressure
pump motor in FIG. 1.
[0010] FIG. 3 is a sectional view of a plate, a power transmission
mechanism, and a circulation mechanism in FIG. 1.
DESCRIPTION OF EMBODIMENTS
[0011] Hereinafter, referring the drawings, a hydraulic drive unit
100 serving as a fluid pressure drive unit according to an
embodiment of the present invention will be described. In the
hydraulic drive unit 100, working oil is used as a working fluid.
It should be noted that instead of the working oil, other fluids
such as working water may be used as the working fluid.
[0012] Firstly, referring to FIGS. 1 to 3, a configuration of the
hydraulic drive unit 100 will be described.
[0013] The hydraulic drive unit 100 is to supply the working oil to
and drive a hydraulic actuator (not shown) serving as a fluid
pressure actuator. The hydraulic drive unit 100 is applied to a
hybrid construction machine such as a power shovel for driving the
hydraulic actuator with the working oil discharged from a main
hydraulic pump (not shown) which is driven by a prime mover.
[0014] As shown in FIG. 1, the hydraulic drive unit 100 is provided
with a hydraulic pump motor 1 serving as a fluid pressure pump
motor which includes a hydraulic pump 10 serving as a fluid
pressure pump for suctioning and discharging the working oil, and a
hydraulic motor 20 serving as a fluid pressure motor to be driven
and rotated with the supplied working oil.
[0015] The hydraulic drive unit 100 is also provided with an
electric motor 30 arranged in parallel to the hydraulic pump motor
1, a plate 40 having an identical surface to which the hydraulic
pump motor 1 and the electric motor 30 are attached, a power
transmission mechanism 50 for transmitting a power between a
rotation shaft 2 of the hydraulic pump motor 1 and a rotation shaft
(not shown) of the electric motor 30, and a circulation mechanism
60 for guiding lubricant oil serving as a lubricating fluid in the
power transmission mechanism 50 and cooling the electric motor
30.
[0016] The hydraulic pump 10 and the hydraulic motor 20 forming the
hydraulic pump motor 1 are respectively swash-plate-type variable
piston pump motors. The hydraulic motor 20 is a piston pump motor
of a larger scale than the hydraulic pump 10.
[0017] As shown in FIG. 2, the hydraulic pump motor 1 is provided
with a casing 3 for accommodating the hydraulic pump 10 and the
hydraulic motor 20, and the single rotation shaft 2 rotatably and
axially supported on the casing 3 and commonly used for the
hydraulic pump 10 and the hydraulic motor 20.
[0018] The casing 3 has a flange portion 3a fastened to the plate
40 by bolts. The casing 3 has a supply and emission passage 4
through which the working oil to be supplied to the hydraulic pump
10 flows and the working oil emitted from the hydraulic motor 20
flows, a discharge passage 5 through which the working oil
discharged from the hydraulic pump 10 flows, and a return passage 6
through which the working oil returned from the hydraulic actuator,
to be supplied to the hydraulic motor 20 flows.
[0019] The supply and emission passage 4 communicates with a tank
(not shown) in which the working oil is stored. The discharge
passage 5 and the return passage 6 communicate with the hydraulic
actuator. The supply and emission passage 4 is provided to oppose
the discharge passage 5 and the return passage 6.
[0020] The hydraulic pump 10 and the hydraulic motor 20 are
arranged to oppose each other in the axial direction of the
rotation shaft 2 across the supply and emission passage 4, the
discharge passage 5, and the return passage 6.
[0021] The hydraulic pump 10 suctions the working oil of the supply
and emission passage 4 and discharges to the discharge passage 5.
The hydraulic pump 10 assists drive of the hydraulic actuator by
the main hydraulic pump with the discharged working oil. The
hydraulic pump 10 is provided with a cylinder block 11 coupled to
the rotation shaft 2, a plurality of pistons 13 respectively
accommodated in a plurality of cylinders 12 which is defined in the
cylinder block 11, a swash plate 14 for letting the pistons 13 in
sliding contact reciprocate, and a port plate 15 to be brought into
sliding contact with an end surface of the cylinder block 11.
[0022] The cylinder block 11 is formed into a substantially
columnar shape, and rotated integrally with the rotation shaft 2.
The cylinder block 11 is driven and rotated by the rotation shaft
2. In the cylinder block 11, the plurality of cylinders 12 is
formed in parallel with the rotation shaft 2.
[0023] The cylinders 12 are arranged on an identical circumference
of the cylinder block 11 centering on the rotation shaft 2 in an
annular manner at fixed intervals. The pistons 13 are inserted into
the respective cylinders 12, and volume chambers 12a are defined
between the cylinders and the pistons 13. The volume chambers 12a
communicate with the port plate 15 through communication holes.
[0024] When the cylinder block 11 is rotated together with the
rotation shaft 2, the pistons 13 are brought into sliding contact
with the swash plate 14. Thereby, the pistons 13 reciprocate in the
cylinders 12 in accordance with a tilting angle of the swash plate
14, and hence extend and contract the volume chambers 12a.
[0025] The swash plate 14 is provided in such a manner that the
tilting angle is adjustable by a capacity switching actuator (not
shown). The swash plate 14 is tiltable into a state shown in FIG. 2
from a state where the swash plate is perpendicular to the rotation
shaft 2 with the tilting angle of zero. The tilting angle of the
swash plate 14 is steplessly adjusted by the capacity switching
actuator.
[0026] The port plate 15 is formed into a disc shape, and has a
through hole into which the rotation shaft 2 is inserted in center
thereof. The port plate 15 has a supply port 15a formed into an arc
shape centering on the rotation shaft 2, the supply port providing
communication between the supply and emission passage 4 and the
volume chambers 12a, and a discharge port 15b similarly formed into
an arc shape centering on the rotation shaft 2, the discharge port
providing communication between the discharge passage 5 and the
volume chambers 12a.
[0027] In the hydraulic pump 10, a region where the pistons 13 are
brought into sliding contact with the swash plate 14 and the volume
chambers 12a are extended is a suctioning region, and a region
where the pistons 13 are brought into sliding contact with the
swash plate 14 and the volume chambers 12a are contracted is a
discharging region. The supply port 15a is formed in correspondence
with the suctioning region, and the discharge port 15b is formed in
correspondence with the discharging region. Thereby, in accordance
with rotation of the cylinder block 11, the working oil is
suctioned into the volume chambers 12a facing the supply port 15a,
and the working oil is discharged from the volume chambers 12a
facing the discharge port 15b.
[0028] The hydraulic motor 20 is driven and rotated with the
working oil emitted from the hydraulic actuator. The hydraulic
motor 20 is provided with a cylinder block 21 coupled to the
rotation shaft 2, a plurality of pistons 23 respectively
accommodated in a plurality of cylinders 22 which is defined in the
cylinder block 21, a swash plate 24 for letting the pistons 23 in
sliding contact reciprocate, and a port plate 25 to be brought into
sliding contact with an end surface of the cylinder block 21. The
cylinder block 21, the cylinders 22, the pistons 23, and the swash
plate 24 of the hydraulic motor 20 only have different size from
the configurations of the above hydraulic pump 10 but have the same
configurations. Thus, description thereof is omitted.
[0029] The port plate 25 is formed into a disc shape, and has a
through hole into which the rotation shaft 2 is inserted in center
thereof. The port plate 25 has a supply port 25a formed into an arc
shape centering on the rotation shaft 2, the supply port 25a
providing communication between the return passage 6 and volume
chambers 22a, and an emission port 25b similarly formed into an arc
shape centering on the rotation shaft 2, the emission port 25b
providing communication between the supply and emission passage 4
and the volume chambers 22a.
[0030] In the hydraulic motor 20, a region where the pistons 23 are
brought into sliding contact with the swash plate 24 and the volume
chambers 22a are extended is a suctioning region, and a region
where the pistons 23 are brought into sliding contact with the
swash plate 24 and the volume chambers 22a are contacted is an
emitting region. The supply port 25a is formed in correspondence
with the suctioning region, and the emission port 25b is formed in
correspondence with the emitting region. Thereby, in accordance
with rotation of the cylinder block 21, the working oil is
suctioned into the volume chambers 22a facing the supply port 25a,
and the working oil is emitted from the volume chambers 22a facing
the emission port 25b.
[0031] The electric motor 30 drives and rotates the hydraulic pump
10, and is capable of generating regenerative electric power by the
rotation of the hydraulic motor 20. The electric power generated in
the electric motor 30 is stored in an electric power storage device
(not shown). The electric motor 30 drives and rotates the hydraulic
pump 10 by using the regenerative electric power regenerated by the
rotation of the hydraulic motor 20 and stored in the electric power
storage device.
[0032] As shown in FIG. 1, the plate 40 is a plate shape member
having one surface 40a to which the hydraulic pump motor 1 and the
electric motor 30 are attached, and the other surface 40b to which
a casing 51 of the power transmission mechanism 50 is attached.
Thereby, the power transmission mechanism 50 is provided to oppose
the hydraulic pump motor 1 and the electric motor 30 across the
plate 40. In the plate 40, a through hole (not shown) through which
the rotation shaft 2 of the hydraulic pump motor 1 passes, a
through hole (not shown) through which a rotation shaft of the
electric motor 30 passes, and a reflux port 42 (refer to FIG. 3)
through which the lubricant oil after cooling the electric motor 30
is refluxed are formed.
[0033] As described above, in the hydraulic drive unit 100, the
hydraulic pump motor 1 and the electric motor 30 are arranged in a
U shape through the plate 40 and the power transmission mechanism
50. Therefore, as the hydraulic pump motor 1 and the electric motor
30 are arranged in parallel, the entire length of the hydraulic
drive unit 100 can be shortened. Thus, mountability of the
hydraulic drive unit 100 to the hybrid construction machine can be
improved.
[0034] It should be noted that instead of the U shape arrangement,
the hydraulic pump motor 1 may be attached to the one surface 40a
of the plate 40, and the electric motor 30 may be attached to the
other surface 40b of the plate 40. The hydraulic pump motor 1 and
the electric motor 30 may be arranged in series across the plate
40.
[0035] As shown in FIG. 3, the power transmission mechanism 50 is
provided with the casing 51 fixed to the plate 40, a first gear 52
to be rotated integrally with the rotation shaft 2 of the hydraulic
pump motor 1, a second gear 53 to be rotated integrally with the
rotation shaft of the electric motor 30, and an idle gear 54
provided between the first gear 52 and the second gear 53, the idle
gear 54 for transmitting the power.
[0036] The casing 51 accommodates the first gear 52, the second
gear 53, and the idle gear 54. The casing 51 is fastened by bolts
in a state where an opening end surface 51a is abutted with the
other surface 40b of the plate 40. The lubricant oil is charged
inside the casing 51. The casing 51 has a through hole 51b formed
on an end surface on the opposite side of the opening end surface
51a, the through hole 51b into which a rotation shaft of the idle
gear 54 is inserted.
[0037] The first gear 52 has a recessed portion 52a formed on a
rotation shaft, the recessed portion into which the rotation shaft
2 of the hydraulic pump motor 1 is inserted and fitted. Thereby,
the first gear 52 is rotated integrally with the rotation shaft 2
of the hydraulic pump motor 1. In the first gear 52, one end of the
rotation shaft is rotatably and axially supported on the plate 40
by a first bearing 52b, and the other end of the rotation shaft is
rotatably and axially supported on the casing 51 by a second
bearing 52c.
[0038] Similarly, the second gear 53 has a recessed portion 53a
formed on a rotation shaft, the recessed portion into which the
rotation shaft of the electric motor 30 is inserted and fitted.
Thereby, the second gear 53 is rotated integrally with the rotation
shaft of the electric motor 30. In the second gear 53, one end of
the rotation shaft is rotatably and axially supported on the plate
40 by a first bearing 53b, and the other end of the rotation shaft
is rotatably and axially supported on the casing 51 by a second
bearing 53c.
[0039] The idle gear 54 is respectively meshed with the first gear
52 and the second gear 53 and transmits the power between the
gears. In the idle gear 54, one end of the rotation shaft is
rotatably and axially supported on the plate 40 by a first bearing
54b, and a substantially center part of the rotation shaft is
rotatably and axially supported on the casing 51 by a second
bearing 54c. The other end of the rotation shaft of the idle gear
54 is inserted into the through hole 51b and extended in a casing
61 of the circulation mechanism 60.
[0040] In such a way, by providing the idle gear 54 between the
first gear 52 and the second gear 53, even in a case where the
hydraulic pump motor 1 and the electric motor 30 are relatively
distant from each other, diameters of the first gear 52 and the
second gear 53 are suppressed from being large. Therefore, the
power transmission mechanism 50 can be downsized, and the entire
hydraulic drive unit 100 can be downsized.
[0041] By adjusting a gear ratio between the first gear 52 and the
second gear 53, a reduction ratio between the hydraulic pump motor
1 and the electric motor 30 can be set to be a proper value.
[0042] The circulation mechanism 60 is provided with the casing 61
whose interior communicates with an interior of the casing 51 of
the power transmission mechanism 50, an impeller 62 serving as a
rotation member to be rotated integrally with the idle gear 54 in
the casing 61, a supply flow passage 63 for guiding the lubricating
fluid stirred up by the impeller 62 to the electric motor 30, and a
reflux flow passage 64 for returning the lubricating fluid guided
to the electric motor 30 into the power transmission mechanism
50.
[0043] The casing 61 is fixed in a state where an opening end
surface 61a is abutted with the casing 51 of the power transmission
mechanism 50. The lubricant oil charged in the interior of the
casing 51 of the power transmission mechanism 50 flows into the
interior of the casing 61. In the casing 61, a third bearing 54d
for rotatably and axially supporting the other end of the rotation
shaft of the idle gear 54 is provided.
[0044] The impeller 62 is a rotating part provided coaxially with
the idle gear 54. The impeller 62 is attached to the rotation shaft
of the idle gear 54. The impeller 62 is provided between the second
bearing 54c and the third bearing 54d. It should be noted that the
impeller 62 may be provided anywhere between the first bearing 54b
and the third bearing 54d.
[0045] The impeller 62 is rotated when the power transmission
mechanism 50 transmits the power between the hydraulic pump motor 1
and the electric motor 30, and stirs up the lubricant oil in the
casing 51 of the power transmission mechanism 50 guided into the
casing 61 toward an outer circumference. In accordance with an
increase in the rotation number of the electric motor 30, the
rotation number of the impeller 62 is increased. Therefore, in
accordance with an increase in a heat generation amount of the
electric motor 30, an amount of the lubricant oil stirred up by the
impeller 62 is increased.
[0046] Since the impeller 62 is rotated integrally with the idle
gear 54, rotational fluctuation of the idle gear 54 can be reduced
by the flywheel effect. Therefore, noises due to the rotational
fluctuation of the idle gear 54 can be reduced.
[0047] It should be noted that instead of providing the impeller 62
to be rotated integrally with the idle gear 54, the impeller may be
provided to be rotated integrally with the first gear 52 or the
second gear 53. A plurality of impellers 62 may be provided, for
example, impellers 62 are respectively provided in the first gear
52 and the second gear 53. That is, the impeller 62 is to be
rotated integrally with at least any one of the first gear 52, the
second gear 53, and the idle gear 54.
[0048] Instead of the impeller 62, another mechanism such as a
cylinder to be driven by the rotation of the idle gear 54, the
cylinder for stirring up the lubricant oil may be provided. That
is, as long as the mechanism is capable of converting rotation
motion of the idle gear 54 and stirring up the lubricant oil, any
mechanism may be provided.
[0049] As shown in FIG. 1, the supply flow passage 63 is a pipe
pulled out to an exterior from the casing 61 and coupled to an
exterior of the electric motor 30. The supply flow passage 63 is
pulled out from a surface of the casing 61 facing the outer
circumference of the impeller 62. The lubricant oil guided through
the supply flow passage 63 is supplied to an oil jacket (not shown)
formed inside the electric motor 30, and cools the electric motor
30.
[0050] The reflux flow passage 64 is a pipe pulled out to the
exterior from the electric motor 30 and coupled to the reflux port
42 (refer to FIG. 3) formed in the plate 40. Through the reflux
flow passage 64, the lubricant oil emitted from the oil jacket of
the electric motor 30 is refluxed into the casing 51 of the power
transmission mechanism 50. It should be noted that instead of the
configuration in which the supply flow passage 63 and the reflux
flow passage 64 are provided in the exterior of the electric motor
30, the supply flow passage 63 and the reflux flow passage 64 may
be formed inside a casing of the electric motor 30.
[0051] Next, actions of the hydraulic drive unit 100 will be
described.
[0052] In a case where the hydraulic drive unit 100 assists the
drive of the hydraulic actuator by the main hydraulic pump, the
electric motor 30 is rotated by using the electric power
preliminarily stored in the electric power storage device. By the
rotation of the electric motor 30, the rotation shaft 2 of the
hydraulic pump motor 1 is driven and rotated via the power
transmission mechanism 50.
[0053] Regarding the hydraulic pump 10, the tilting angle of the
swash plate 14 is switched to have a predetermined value which is
more than zero by the capacity switching actuator. In the hydraulic
pump 10, in accordance with the rotation of the cylinder block 11,
the pistons 13 reciprocate in the cylinders 12. By this
reciprocation of the pistons 13, the working oil from the tank is
suctioned into the volume chambers 12a through the supply port 15a
of the port plate 15. The working oil discharged from the volume
chambers 12a is guided to the discharge passage 5 through the
discharge port 15b of the port plate 15.
[0054] Thereby, the working oil discharged from the hydraulic drive
unit 100 is supplied for the drive of the hydraulic actuator, and
assists the drive of the hydraulic actuator by the main hydraulic
pump.
[0055] When the electric motor 30 drives and rotates the hydraulic
pump motor 1, the rotation of the second gear 53 is transmitted to
the idle gear 54, and the rotation of the idle gear 54 is
transmitted to the first gear 52. By rotating the idle gear 54, the
impeller 62 of the circulation mechanism 60 is rotated.
[0056] When the impeller 62 is rotated, the lubricant oil in the
casing 51 of the power transmission mechanism 50 guided into the
casing 61 of the circulation mechanism 60 through the through hole
51b is stirred up and supplied to the oil jacket of the electric
motor 30 through the supply flow passage 63. Therefore, the
electric motor 30 can be cooled by heat exchange between the
lubricant oil and the electric motor 30. The lubricant oil after
cooling the electric motor 30 is refluxed from the oil jacket of
the electric motor 30 into the casing 51 of the power transmission
mechanism 50 through the reflux flow passage 64.
[0057] As described above, when the electric motor 30 drives and
rotates the hydraulic pump motor 1, the impeller 62 is rotated in
accordance with transmission of the power by the power transmission
mechanism 50, and the lubricant oil is guided to the electric motor
30. Therefore, since there is no need for providing a cooling
system of cooling the electric motor 30 from the exterior, a
cooling mechanism of the electric motor 30 in the hydraulic drive
unit 100 can be simplified.
[0058] Only when the power transmission mechanism 50 transmits the
power, that is, when the electric motor 30 is rotated and generates
heat, the lubricant oil can be supplied and cooling can be
performed. Therefore, in comparison to a case where the cooling is
always performed by using the cooling system of cooling the
electric motor 30 from the exterior, cooling efficiency can be more
enhanced.
[0059] Since the lubricant oil stirred up by the impeller 62 cools
the electric motor 30 and is refluxed, the lubricant oil in the
power transmission mechanism 50 is circulated. Therefore, the
lubricant oil in the power transmission mechanism 50 flows and
moves. Thus, the bearings for axially supporting the first gear 52,
the second gear 53, and the idle gear 54 are prevented from being
burnt out due to shortage of the lubricant oil.
[0060] At this time, the hydraulic motor 20 is retained in such a
manner that a tilting angle of the swash plate 24 becomes zero by
the capacity switching actuator. Therefore, since the pistons 23 do
not reciprocate in the cylinders 22, a displacement volume by the
pistons 23 becomes zero. Thus, since the hydraulic motor 20 does
not supply and emit the working oil but only runs idle, a drive
loss of the hydraulic motor 20 is suppressed.
[0061] Meanwhile, in a case where the regenerative electric power
is generated with the working oil emitted from the hydraulic
actuator, regarding the hydraulic motor 20, the tilting angle of
the swash plate 24 is switched to be a predetermined value which is
more than zero by the capacity switching actuator. In the hydraulic
motor 20, in accordance with the rotation of the cylinder block 21,
the pistons 23 reciprocate in the cylinders 22. By this
reciprocation of the pistons 23, the pressurized working oil
returned from the hydraulic actuator through the return passage 6
flows into the volume chambers 22a through the supply port 25a of
the port plate 25. The pistons 23 reciprocate in the cylinders 22,
and the cylinder block 21 is driven and rotated. The working oil
flowing into the volume chambers 22a is emitted to the supply and
emission passage 4 through the emission port 25b of the port plate
25, and refluxed to the tank.
[0062] The rotation shaft 2 is rotated integrally with the cylinder
block 21. The rotation of the rotation shaft 2 is transmitted to
the rotation shaft of the electric motor 30 via the power
transmission mechanism 50. Thereby, the electric motor 30 can
generate and store the regenerative electric power in the electric
power storage device.
[0063] When the rotation of the rotation shaft 2 of the hydraulic
pump motor 1 is transmitted to the electric motor 30, the rotation
of the first gear 52 is transmitted to the idle gear 54, and the
rotation of the idle gear 54 is transmitted to the second gear 53.
By rotating the idle gear 54, the impeller 62 of the circulation
mechanism 60 is rotated. Therefore, as well as a case where the
electric motor 30 drives and rotates the hydraulic pump motor 1,
the electric motor 30 can be cooled by the heat exchange between
the lubricant oil and the electric motor 30.
[0064] At this time, the hydraulic pump 10 is retained in such a
manner that the tilting angle of the swash plate 14 becomes zero by
the capacity switching actuator. Therefore, since the pistons 13 do
not reciprocate in the cylinders 12, a displacement volume by the
pistons 13 becomes zero. Thus, since the hydraulic pump 10 does not
supply and emit the working oil but only runs idle, a drive loss of
the hydraulic pump 10 is suppressed.
[0065] It should be noted that in a case where the hydraulic drive
unit 100 assists supply of the working oil to a plurality of
hydraulic actuators by the main hydraulic pump, there is sometimes
a case where drive of one hydraulic actuator is assisted and the
working oil is refluxed from other hydraulic actuators.
[0066] According to the above embodiment, the following effects are
obtained.
[0067] The circulation mechanism 60 for guiding the lubricant oil
in the power transmission mechanism 50 by the rotation of the
impeller 62 and cooling the electric motor 30 is provided. This
impeller 62 is rotated integrally with the idle gear 54 for
transmitting the power between the first gear 52 and the second
gear 53. Therefore, when the electric motor 30 drives and rotates
the hydraulic pump motor 1, the impeller 62 is rotated in
accordance with the transmission of the power by the power
transmission mechanism 50, and the lubricant oil is guided to the
electric motor 30. Thus, since there is no need for providing the
cooling system of cooling the electric motor 30 from the exterior,
the cooling mechanism of the electric motor 30 in the hydraulic
drive unit 100 can be simplified.
[0068] Embodiments of the present invention were described above,
but the above embodiments are merely examples of applications of
the present invention, and the technical scope of the present
invention is not limited to the specific constitutions of the above
embodiments.
[0069] For example, the hydraulic drive unit 100 is to assist the
drive of the hydraulic actuator by the main hydraulic pump.
However, instead of this, the hydraulic actuator may be driven by
using only the hydraulic drive unit 100.
[0070] Both the hydraulic pump 10 and the hydraulic motor 20 are
swash-plate-type piston pump motors. However, as long as the motors
are variable motors in which a suction and discharge capacity is
adjustable to be zero, the hydraulic pump and the hydraulic motor
may be other types. The circulation mechanism 60 may supply the
lubricant oil to the hydraulic pump motor 1.
[0071] This application claims priority based on Japanese Patent
Application No. 2012-075565 filed with the Japan Patent Office on
Mar. 29, 2012, the entire contents of which are incorporated into
this specification.
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