U.S. patent application number 12/369121 was filed with the patent office on 2009-08-13 for wheel motor device.
Invention is credited to Koji IWAKI.
Application Number | 20090200858 12/369121 |
Document ID | / |
Family ID | 39590813 |
Filed Date | 2009-08-13 |
United States Patent
Application |
20090200858 |
Kind Code |
A1 |
IWAKI; Koji |
August 13, 2009 |
Wheel Motor Device
Abstract
A wheel motor device according to the present invention includes
a hydraulic motor main body forming an HST in cooperation with the
hydraulic pump main body, a motor shaft supporting the hydraulic
motor main body in a relatively non-rotatable manner, a
speed-reduction gear mechanism for reducing the speed of the
rotational power output from the motor shaft, a first output member
for outputting the rotational power whose speed has been reduced by
the speed-reduction gear mechanism toward a corresponding first
driving wheel, a casing accommodating the hydraulic motor main body
and the speed-reduction gear mechanism, and a brake mechanism
selectively and operatively applying a brake force to the first
output member. The brake mechanism includes a brake shaft supported
by the casing, a speed-increasing gear mechanism for increasing the
speed of the rotational power output from the motor shaft and
operatively transmitting the same to the brake shaft, and a brake
unit for selectively and operatively applying the brake force to
the brake shaft.
Inventors: |
IWAKI; Koji; (Hyogo,
JP) |
Correspondence
Address: |
STERNE, KESSLER, GOLDSTEIN & FOX P.L.L.C.
1100 NEW YORK AVENUE, N.W.
WASHINGTON
DC
20005
US
|
Family ID: |
39590813 |
Appl. No.: |
12/369121 |
Filed: |
February 11, 2009 |
Current U.S.
Class: |
303/11 |
Current CPC
Class: |
B60K 2007/0046 20130101;
B60Y 2200/223 20130101; B60K 17/16 20130101; B60K 17/043 20130101;
B60K 7/0015 20130101; B60L 2220/46 20130101; B60K 17/105 20130101;
B60K 2007/0061 20130101 |
Class at
Publication: |
303/11 |
International
Class: |
B60T 13/18 20060101
B60T013/18 |
Foreign Application Data
Date |
Code |
Application Number |
Feb 13, 2008 |
EP |
08151379.8 |
Claims
1. A wheel motor device applied in a working vehicle including a
driving power source, a hydraulic pump main body operatively driven
by the driving source and a pair of first and second driving wheels
facing to each other along a widthwise direction of the vehicle,
the wheel motor device comprising a hydraulic motor main body
forming an HST in cooperation with the hydraulic pump main body, a
motor shaft supporting the hydraulic motor main body in a
relatively non-rotatable manner, a speed-reduction gear mechanism
for reducing the speed of the rotational power output from the
motor shaft, a first output member for outputting the rotational
power whose speed has been reduced by the speed-reduction gear
mechanism toward the corresponding first driving wheel, a casing
accommodating the hydraulic motor main body and the speed-reduction
gear mechanism, and a brake mechanism selectively and operatively
applying a brake force to the first output member, the wheel motor
device being characterized in that, the brake mechanism includes a
brake shaft supported by the casing, a speed-increasing gear
mechanism for increasing the speed of the rotational power output
from the motor shaft and operatively transmitting the same to the
brake shaft, and a brake unit for selectively and operatively
applying the brake force to the brake shaft.
2. A wheel motor device according to claim 1, wherein the casing
includes a motor case which supports the motor shaft at a position
displaced from a rotational axis line of the first driving wheel in
such a manner that the motor shaft is substantially parallel to the
rotational axis line of the first driving wheel and is rotatable
around its axis line and which accommodates the hydraulic motor
main body supported by the motor shaft, and a gear case connected
to a side of the motor case which is close to the first driving
wheel, the gear case supporting the first output shaft so as to be
positioned coaxially with the rotational axis line of the first
driving wheel in a state of being rotatable manner around its axis
line and accommodating the speed-reduction gear mechanism, the
brake shaft is supported in a rotatable manner around its axis line
by the gear case at a position displaced from the first driving
wheel around the rotational axis line of the first driving wheel,
in such a manner that the brake shaft is substantially parallel to
the rotational axis line of the first driving wheel and an end
portion of the brake shaft on a side away from the first driving
wheel is extended outward from the gear case, and the brake unit
includes a brake disk supported by the outwardly-extending end
portion of the brake shaft in a relatively non-rotatable manner,
and is configured so as to selectively apply the brake force to the
brake disk on the basis of an operation from the outside.
3. A wheel motor device according to claim 2, wherein the gear case
is capable of supporting the brake shaft at plural positions around
the rotational axis line of the first output member.
4. A wheel motor device according to claim 3, wherein the plural
positions include first and second portions which are symmetrical
to each other with an imaginary vertical plane as a reference, the
imaginary vertical plane passing through the rotation axis line of
the first output member.
5. A wheel motor device according to claim 2, wherein the brake
unit includes a mounting stay detachably connected to the gear
case, a brake operation shaft supported in a rotatable manner
around its axis line by the mounting stay in a state that its axis
line extends substantially parallel to a disk surface of the brake
disk and its first end portion having a non-circular
cross-sectional shape overlaps with the brake disk as viewed along
the rotational axis line of the brake disk, and a push-side brake
pad supported by the first end portion in such a manner as to come
close to or separate from the brake disk in accordance with the
rotation of the brake operation shaft about the axis line.
6. A wheel motor device according to claim 5, wherein the brake
unit further includes a fixed-side brake pad detachably supported
by the gear case in such a manner as to face to the push-side brake
pad across the brake disk.
7. A wheel motor device according to of claim 2, further comprising
a brake-shaft-side coupling supported in a relatively non-rotatable
manner by a portion of the brake shaft which is away from the first
driving wheel than the brake disk, wherein the brake-shaft-side
coupling has a concave/convex engagement portion at an end surface
on a side opposite from the corresponding first driving wheel, the
concave/convex engagement portion being opened toward the other
second driving wheel.
8. A wheel motor device according to claim 1, further comprising a
second output member which is operatively connected trough the
speed-reduction gear mechanism to the motor shaft and which outputs
a driving force toward the second driving wheel.
9. A wheel motor device according to claim 8, wherein, the first
and second output members are positioned coaxially with each other,
the wheel motor device further comprises a differential gear
mechanism including a ring gear operatively connected to the motor
shaft, first and second side bevel gears respectively supported on
the first and second output members in a relatively non-rotatable
manner, a pinion shaft rotating along with the ring gear, and a
bevel pinion supported on the pinion shaft in a relatively
rotatable manner in a state of being engaged with the first and
second side bevel gears, a driving-side gear with a small diameter
provided on the motor shaft so as to engage with the ring gear
forms the speed-reduction gear mechanism in cooperation with the
ring gear, and a driven-side gear with a small diameter provided on
the brake shaft so as to engage with the ring gear forms the
speed-increasing gear mechanism in cooperation with the ring
gear.
10. A wheel motor device according to claim 1, wherein, the motor
shaft is displaced from the rotational axis line in a state of
being substantially parallel to the rotational axis line, the first
output member is disposed coaxially with the rotational axis line
of the first driving wheel, the speed-reduction gear mechanism
includes a driving-side gear with a small diameter which is
provided on the motor shaft in a relatively non-rotatable manner,
and an output gear with a large diameter which is provided on the
first output member in a relatively non-rotatable manner and which
is engaged with the driving-side gear, the output gear being
embodied by an internal gear, the brake shaft is provided with a
driven-side gear with a small diameter which is engaged with the
output gear, and the output gear and the driven-side gear form the
speed-increasing gear mechanism.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to a wheel motor device which
has a hydraulic motor main body forming an HST in cooperation with
a hydraulic pump main body that is operatively driven by a drive
source and which is placed separately from the hydraulic pump main
body such that it can be positioned close to a corresponding
driving wheel.
[0003] 2. Related Art
[0004] There has been conventionally known a wheel motor device
which has a hydraulic motor main body forming an HST in cooperation
with a hydraulic pump main body that is operatively driven by a
drive source and which is placed separately from the hydraulic pump
main body such that it can be positioned close to a corresponding
driving wheel (see, for example, Japanese Unexamined Patent
Publication No. 2006-096112, Japanese Unexamined Patent Publication
No. 2005-195070, and Japanese Unexamined Patent Publication No.
2005-028914, which are hereinafter referred to as prior document 1
to 3, respectively).
[0005] The wheel motor device can be preferably used in a working
vehicle such as a mid-mount mower tractor which is required to
ensure a free space between a pair of driving wheels usable as an
installation space for a rear discharge duct and the like.
[0006] More specifically, the wheel motor devices described in the
prior documents 1 to 3 include a speed-reduction gear mechanism for
reducing a speed of the rotational power output from the hydraulic
motor main body, an output member for outputting the rotational
power whose rotational speed has been reduced by the
speed-reduction gear mechanism to the corresponding driving wheel,
and a brake mechanism capable of operatively and selectively
applying a braking force to the output member, in addition to the
hydraulic motor main body fluidly connected to the hydraulic pump
main body.
[0007] Since the conventional wheel motor devices include the
speed-reduction gear mechanism, it is possible to employ a
high-rotation/low-torque type hydraulic motor main body as the
hydraulic motor main body. This can reduce the size of the
hydraulic motor main body and also can reduce the leak of the
hydraulic fluid from the hydraulic motor main body, thereby
enhancing power transmission efficiency of the HST.
[0008] Meanwhile, it is desirable to reduce the size of the wheel
motor device including the above-described components with respect
to the direction of the rotational axis line of the corresponding
driving wheel (namely, in the widthwise direction of the working
vehicle).
[0009] Namely, by reducing the size of the wheel motor device in
the direction of the rotational axis line, it is possible to ensure
the free space between the pair of driving wheels as much as
possible.
[0010] Further, the wheel motor device is desired to reduce the
size of the brake mechanism as much as possible, while increasing
the degree of freedom in designing the brake mechanism.
[0011] However, there exists no wheel motor device capable of
attaining the above-described two requirements at the same
time.
[0012] Specifically, the wheel motor device described in the prior
document 1 includes a motor shaft positioned inwards in the vehicle
widthwise direction than the corresponding driving wheel with being
parallel to the rotational axis line of the corresponding driving
wheel, a hydraulic motor main body supported on the motor shaft in
a relatively non-rotatable manner, a speed-reduction gear mechanism
operatively connected to an outer end portion of the motor shaft in
the vehicle-widthwise direction (the end portion on as side close
to the driving wheel), an output member for outputting the
rotational power inputted from the speed-reduction gear mechanism
to the driving wheel, and a brake mechanism positioned inwards in
the vehicle-widthwise direction than the hydraulic motor main body
in such a way as to selectively apply a braking force to an inner
end portion of the motor shaft in the vehicle-widthwise direction
(the end portion on a side away from the driving wheel).
[0013] Since the wheel motor device described in the prior document
1 is configured so that the brake mechanism applies the braking
force to the motor shaft which is positioned on an upstream side in
a power transmission direction than the speed-reduction gear
mechanism, it is possible to achieve a reduction of the brake
capacity required for the brake mechanism, thereby reducing the
size of the brake mechanism.
[0014] However, the brake mechanism is positioned inwards in the
vehicle-widthwise direction than the hydraulic motor main body,
thereby inducing the problem that the free space between the pair
of driving wheels is reduced due to the presence of the brake
mechanism.
[0015] The wheel motor device described in the prior document 2
includes a motor shaft placed positioned inwards in the
vehicle-widthwise direction than the corresponding driving wheel
with being parallel to the rotational axis line of the
corresponding driving wheel, a hydraulic motor main body supported
on the motor shaft in a relatively non-rotatable manner, a
speed-reduction gear mechanism operatively connected to an outer
end of the motor shaft in the vehicle-widthwise direction, an
output member for outputting the rotational power inputted from the
speed-reduction gear mechanism to the driving wheel, and a brake
mechanism inserted between the speed-reduction gear mechanism and
the outer end of the motor shaft in the vehicle-widthwise
direction, in the direction of the rotational axis line (in the
vehicle-widthwise direction) in such a way as to selectively and
operatively apply a braking force to the output member.
[0016] Since the wheel motor device described in the prior document
2, similarly to the wheel motor device described in the prior
document 1, is configured so that the brake mechanism applies the
braking force to the motor shaft which is positioned on an upstream
side in a power transmission direction than the speed-reduction
gear mechanism, it is possible to achieve a reduction of the brake
mechanism in size.
[0017] However, the brake mechanism is positioned between the motor
shaft and the speed-reduction gear mechanism with respect to the
vehicle-widthwise direction, thereby inducing the problem that the
free space between the pair of driving wheels is reduced due to the
presence of the brake mechanism.
[0018] The wheel motor device described in the prior document 3
includes a motor shaft positioned inwards in the vehicle-widthwise
direction than the corresponding driving wheel with being parallel
to the rotational axis line of the corresponding driving wheel, a
hydraulic motor main body supported on the motor shaft in a
relatively non-rotatable manner, a speed-reduction gear mechanism
operatively connected to an outer end of the motor shaft in the
vehicle-widthwise direction, an output member for outputting the
rotational power inputted from the speed-reduction gear mechanism
to the driving wheel, and a brake mechanism configured so as to
selectively apply a braking force to an intermediate shaft in the
speed-reduction gear mechanism.
[0019] More specifically, the speed-reduction gear mechanism
includes the intermediate shaft which is placed at a position
displaced from both the motor shaft and the output member with
being parallel to both the shafts, a first speed-reduction gear
train for performing primary speed-reduction between the motor
shaft and the intermediate shaft, and a second speed-reduction gear
train for performing secondary speed-reduction between the
intermediate shaft and the output member.
[0020] Further, the brake mechanism is positioned so as to
selectively and operatively apply the braking force to the outer
end portion of the intermediate shaft in the vehicle-widthwise
direction (the end portion on a side away from the driving
wheel).
[0021] Since the motor wheel device described in the prior document
3, the brake mechanism is configured so as to apply the braking
force to the intermediate shaft displaced from the motor shaft, it
is possible to prevent the wheel motor device from being lengthened
in the vehicle-widthwise direction (in the direction of the axis
line of the motor shaft) due to the provision of the brake
mechanism, thereby preventing the occurrence of the problem that
the free space between the pair of driving wheels is reduced due to
the presence of the brake mechanism.
[0022] However, in the wheel motor device described in the prior
document 3, the position at which the brake mechanism is placed
depends on the position of the intermediate shaft in the
speed-reduction gear mechanism, thereby degrading the degree of
freedom in designing the brake mechanism.
[0023] Further, in the prior document 3, the speed-reduction gear
mechanism applies the braking force to the intermediate shaft which
is rotated at a rotational speed which has been reduced from the
rotational speed of the motor shaft by the first speed-reduction
gear train.
[0024] This structure induces the problem that the brake capacity
of the brake mechanism cannot be sufficiently reduced.
SUMMARY OF THE INVENTION
[0025] The present invention is made in view of the above-described
conventional techniques, and it is an object to provide a wheel
motor device including a hydraulic motor main body, a motor shaft,
a speed-reduction gear mechanism, an output member and a brake
mechanism, the wheel motor device capable of reducing the size of
the brake mechanism as much as possible without degrading the
degree of freedom in designing the brake mechanism.
[0026] The present invention provides, in order to achieve the
object, a wheel motor device applied in a working vehicle including
a driving power source, a hydraulic pump main body operatively
driven by the driving source and a pair of first and second driving
wheels facing to each other along a widthwise direction of the
vehicle, the wheel motor device including a hydraulic motor main
body that forms an HST in cooperation with the hydraulic pump main
body, a motor shaft that supports the hydraulic motor main body in
a relatively non-rotatable manner, a speed-reduction gear mechanism
for reducing the speed of the rotational power output from the
motor shaft, a first output member for outputting the rotational
power whose speed has been reduced by the speed-reduction gear
mechanism toward the corresponding first driving wheel, a casing
that accommodates the hydraulic motor main body and the
speed-reduction gear mechanism, and a brake mechanism that
selectively and operatively applies a brake force to the first
output member, the wheel motor device being characterized in that
the brake mechanism includes a brake shaft supported by the casing,
a speed-increasing gear mechanism for increasing the speed of the
rotational power output from the motor shaft and operatively
transmitting the same to the brake shaft, and a brake unit for
selectively and operatively applying the brake force to the brake
shaft.
[0027] Since the wheel motor device according to the present
invention is configured so as to apply the brake force to the brake
shaft having a rotational power whose speed is increased by the
speed-increasing gear mechanism with respect to the rotational
power of the first output member, it is possible to reduce the size
of the brake mechanism.
[0028] Furthermore, the wheel motor device makes it possible to
freely position the brake shaft, independently of a power
transmission path from the motor shaft to the first output member
through the speed-reduction gear mechanism, thereby enhancing the
degree of freedom in designing the break mechanism.
[0029] In one embodiment, the casing may include a motor case which
supports the motor shaft at a position displaced from a rotational
axis line of the first driving wheel in such a manner that the
motor shaft is substantially parallel to the rotational axis line
of the first driving wheel and is rotatable around its axis line
and which accommodates the hydraulic motor main body supported by
the motor shaft, and a gear case connected to a side of the motor
case which is close to the first driving wheel, the gear case
supporting the first output shaft so as to be positioned coaxially
with the rotational axis line of the first driving wheel in a state
of being rotatable manner around its axis line and accommodating
the speed-reduction gear mechanism.
[0030] In the configuration, the brake shaft is supported in a
rotatable manner around its axis line by the gear case at a
position displaced from the first driving wheel around the
rotational axis line of the first driving wheel, in such a manner
that the brake shaft is substantially parallel to the rotational
axis line of the first driving wheel and an end portion of the
brake shaft on a side away from the first driving wheel is extended
outward from the gear case.
[0031] The brake unit includes a brake disk supported by the
outwardly-extending end portion of the brake shaft in a relatively
non-rotatable manner, and is configured so as to selectively apply
the brake force to the brake disk on the basis of an operation from
the outside.
[0032] According to the one embodiment, it is possible to prevent
the wheel motor device from being enlarged with respect to a
direction along the rotational axis lines of the first and second
driving wheels due to the provision of the brake mechanism, thereby
ensuring a free space between the pair of first and second driving
wheels as much as possible.
[0033] In the one embodiment, the gear case is preferably
configured to be capable of supporting the brake shaft at plural
positions around the rotational axis line of the first output
member.
[0034] According to the configuration, it is possible to enhance
the degree of freedom in positioning the brake mechanism.
[0035] More preferably, the plural positions may include first and
second portions which are symmetrical to each other with an
imaginary vertical plane as a reference, the imaginary vertical
plane passing through the rotation axis line of the first output
member.
[0036] According to the configuration, it is possible to have the
brake shaft in a first wheel motor device for driving the first
driving wheel and the brake shaft in a second wheel motor device
for driving the second driving wheel positioned coaxially with each
other while employing a pair of wheel motor devices having the same
configurations to each other as the first and second wheel motor
devices.
[0037] In the various configurations in the one embodiment, the
brake unit preferably includes a mounting stay detachably connected
to the gear case, a brake operation shaft supported in a rotatable
manner around its axis line by the mounting stay in a state that
its axis line extends substantially parallel to a disk surface of
the brake disk and its first end portion having a non-circular
cross-sectional shape overlaps with the brake disk as viewed along
the rotational axis line of the brake disk, and a push-side brake
pad supported by the first end portion in such a manner as to come
close to or separate from the brake disk in accordance with the
rotation of the brake operation shaft about the axis line.
[0038] More preferably, the brake unit may further include a
fixed-side brake pad detachably supported by the gear case in such
a manner as to face to the push-side brake pad across the brake
disk.
[0039] In the above various configurations in the one embodiment,
the wheel motor device preferably further include a
brake-shaft-side coupling supported in a relatively non-rotatable
manner by a portion of the brake shaft which is away from the first
driving wheel than the brake disk. The brake-shaft-side coupling
has a concave/convex engagement portion at an end surface on a side
opposite from the corresponding first driving wheel, the
concave/convex engagement portion being opened toward the other
second driving wheel.
[0040] In the above various configurations, the wheel motor device
may further include a second output member which is operatively
connected trough the speed-reduction gear mechanism to the motor
shaft and which outputs a driving force toward the second driving
wheel.
[0041] In one embodiment, the first and second output members may
be positioned coaxially with each other.
[0042] In the configuration, the wheel motor device may further
include a differential gear mechanism that includes a ring gear
operatively connected to the motor shaft, first and second side
bevel gears respectively supported on the first and second output
members in a relatively non-rotatable manner, a pinion shaft
rotating along with the ring gear, and a bevel pinion supported on
the pinion shaft in a relatively rotatable manner in a state of
being engaged with the first and second side bevel gears.
[0043] A driving-side gear with a small diameter provided on the
motor shaft so as to engage with the ring gear forms the
speed-reduction gear mechanism in cooperation with the ring gear,
and a driven-side gear with a small diameter provided on the brake
shaft so as to engage with the ring gear forms the speed-increasing
gear mechanism in cooperation with the ring gear.
[0044] According to the configuration, it is possible to
differentially drive the first and second driving wheels only by
providing the single wheel motor device.
[0045] Preferably, the motor shaft is displaced from the rotational
axis line in a state of being substantially parallel to the
rotational axis line, and the first output member is disposed
coaxially with the rotational axis line of the first driving
wheel.
[0046] In the arrangement, the speed-reduction gear mechanism
includes a driving-side gear with a small diameter which is
provided on the motor shaft in a relatively non-rotatable manner,
and an output gear with a large diameter which is provided on the
first output member in a relatively non-rotatable manner and which
is engaged with the driving-side gear, the output gear being
embodied by an internal gear. The brake shaft is provided with a
driven-side gear with a small diameter which is engaged with the
output gear. The output gear and the driven-side gear form the
speed-increasing gear mechanism.
[0047] According to the configuration, it possible to have the
positions of the axis lines of the motor shaft and the brake shaft
come close to the position of the axis line of the first output
member while sufficiently ensuring a speed reducing ratio of the
speed-reduction gear mechanism and a speed increasing ratio of the
speed-increasing gear mechanism, thereby realizing miniaturization
of the wheel motor device in a radial direction.
BRIEF DESCRIPTION OF THE DRAWINGS
[0048] 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.
[0049] FIG. 1 is a schematic side view of a working vehicle to
which a wheel motor device according to a first embodiment of the
present invention is applied.
[0050] FIG. 2 is a schematic rear view of the working vehicle shown
in FIG. 1.
[0051] FIG. 3 is a hydraulic circuit diagram of the working vehicle
shown in FIGS. 1 and 2.
[0052] FIG. 4 is a vertical cross-sectional view of the wheel motor
device according to the first embodiment.
[0053] FIG. 5 is an end view of the wheel motor device taken along
the line V-V in FIG. 4.
[0054] FIG. 6 is a vertical cross-sectional front view of the wheel
motor device, showing a state in which pair of driving wheels of
the working vehicle are driven at a differential-lock state.
[0055] FIG. 7 is an end view of a wheel motor device according to a
modified embodiment of the first embodiment.
[0056] FIG. 8 is a schematic side view of a working vehicle to
which a wheel motor device according to a second embodiment of the
present invention is applied.
[0057] FIG. 9 is a schematic rear view of the working vehicle shown
in FIG. 8.
[0058] FIGS. 10 is a vertical cross-sectional front view of the
wheel motor device according to the second embodiment.
[0059] FIG. 11 is an end view of the wheel motor device taken along
the line XI-XI in FIG. 10.
[0060] FIG. 12 is a vertical cross-sectional front view a wheel
motor device according to a modified embodiment of the present
invention.
[0061] FIG. 13 is an exploded perspective view of the wheel motor
device shown in FIG. 12.
[0062] FIG. 14 is a vertical cross-sectional view of a wheel motor
device according to another modified embodiment of the present
invention.
[0063] FIG. 15 is a vertical cross-sectional view of a wheel motor
device according to still another modified embodiment of the
present invention.
[0064] FIG. 16 is a vertical cross-sectional view of a wheel motor
device according to a comparative example.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
First Embodiment
[0065] Hereinafter, a preferred embodiment of a wheel motor device
according to the present invention will be described, with
reference to the attached drawings.
[0066] First, there will be described an embodiment of a working
vehicle 1A to which wheel motor devices 300A according to the
present embodiment are applied.
[0067] FIGS. 1 to 3 respectively illustrate a schematic side view,
a schematic rear view and a hydraulic circuit diagram of the
working vehicle 1A.
[0068] As illustrated in FIG. 1 and FIG. 2, the working vehicle 1A
is formed to be a mid-mount mower tractor having a mower device 60
at the center in the lengthwise direction of the vehicle and also
having a rear discharge duct provided between a pair of driving
wheels 50(1) and 50(2).
[0069] Specifically, the working vehicle 1A includes a vehicle
frame 10 having a pair of main frames 11 that extends along the
vehicle-lengthwise direction, a driver's seat 20 supported by the
vehicle frame 10, a driving power source 30 supported by the
vehicle frame 10, a pair of non-driving wheels 40 (front wheels in
the present embodiment) and a pair of driving wheels 50(1), 50(2)
(rear wheels in the present embodiment) respectively positioned on
one side and the other side in the vehicle-lengthwise direction,
the mower device 60 positioned between the non-driving wheels 40
and the driving wheels 50(1), 50(2) with respect to the vehicle
lengthwise direction, a discharge duct 70 positioned between the
pair of driving wheels 50(1), 50(2) in order to guide the grass cut
by the working machine to the outsides (rearward in the present
embodiment), a hydraulic pump unit 100 including a hydraulic pump
main body 110 operatively driven by the driving power source 30,
the pair of wheel motor devices 300A(1), 300A(2) which are
positioned away from the hydraulic pump unit 100 so as to be close
to the corresponding driving wheels 50(1), 50(2) and which include
hydraulic motor main body 410 fluidly connected to the hydraulic
pump main body 110 through a pair of first and second hydraulic
fluid lines 200(1), 200(2) so as to form an HST in cooperation with
the hydraulic pump main body 110.
[0070] Further, in the present embodiment, as illustrated in FIG.
3, the hydraulic motor main bodies 410 in the pair of wheel motor
devices 300A(1) and 300A(2) are fluidly connected in parallel to
the hydraulic pump main body 110 in the hydraulic pump unit
100.
[0071] Namely, the hydraulic motor main bodies 410 in the pair of
wheel motor devices 300A(1) and 300B(2) are differentially driven
by the hydraulic pump main body 100 by means of hydraulic
effect.
[0072] Accordingly, as illustrated in FIG. 1 and FIG. 3, in the
present embodiment, the non-driving wheels 40 are formed to be
steering wheels steered by a steering operation member 21, such as
a steering wheel, which is provided at the front of the driver's
sheet 20.
[0073] As illustrated in FIG. 1, the driving power source 30 is
supported in a vibration-preventing manner on the vehicle frame 10
through vibration-preventing rubbers 39.
[0074] More specifically, the vehicle frame 10 has, in addition to
the pair of main frames 11, a cross member 12 which couples the
pair of main frames to each other, wherein the driving power source
30 is supported in a vibration-preventing manner on the cross
member 12 through the vibration-preventing rubbers 39.
[0075] In the present embodiment, the driving power source 30 is of
a vertical crank shaft type in which an output shaft 31 extends
vertically. The driving power source 30 is supported on the upper
surface of the cross member 12 through the vibration-preventing
rubbers 39 at a state where a tip end portion of the output shaft
31 extends below the cross member 12 through an opening formed at
the cross member 12.
[0076] As illustrated in FIG. 1 and FIG. 3, the output shaft 31 is
operatively connected to a pump shaft 120, which will be described
later, in the hydraulic pump unit 100, through a traveling-system
transmission mechanism 80 such as a pulley-and-belt transmission
mechanism, and, also, is operatively connected to an input shaft 61
of the mower device 60 through a PTO-system transmission mechanism
85 such as a pulley-and-belt transmission mechanism.
[0077] Further, as a matter of cause, it is also possible to
employ, as the driving power source 30, a driving power source of a
horizontal crank shaft type, instead of the vertical crank shaft
type.
[0078] As illustrated in FIG. 1 to FIG. 3, the hydraulic pump unit
100 includes the pump shaft 120 which is operatively driven by the
driving power source 30, the hydraulic pump main body 110 supported
by the pump shaft 120 in a relatively non-rotatable manner, and a
pump case 130 which supports the pump shaft 120 in a rotatable
manner around the axis line and also accommodates the hydraulic
pump main body 110.
[0079] In the present embodiment, the hydraulic pump main body 110
is of an axial piston type. Namely, the hydraulic pump main body
110 includes a pump-side cylinder block (not illustrated) supported
by the pump shaft 120 in a relatively non-rotatable manner, and
plural pump-side pistons (not illustrated) which are accommodated
in the pump-side cylinder block in a relatively non-rotatable
manner around the axis line of the pump shaft and in a
reciprocating manner along the axis line.
[0080] As described above, the hydraulic pump main body 110 and the
hydraulic motor main bodies 410 form an HST.
[0081] Accordingly, at least one of the hydraulic pump main body
110 and the hydraulic motor main bodies 410 is formed to be of a
variable displacement type in which its suction/discharge amount
could be changed.
[0082] As illustrated in FIG. 3, in the present embodiment, the
hydraulic pump main body 110 is of a variable displacement type,
while the hydraulic motor main bodies 410 are of a fixed
displacement type.
[0083] Accordingly, as illustrated in FIG. 3, the hydraulic pump
unit 100 has a displacement adjustment mechanism 140 for changing
the suction/discharge amount of the hydraulic pump main body 110,
in addition to the above-described components.
[0084] The displacement adjustment mechanism 140 may include a
movable swash plate (not illustrated) which directly or indirectly
engages with free end portions of the pump-side pistons to define
the range in which the pump-side pistons reciprocates, and a
control shaft 141 (see FIG. 1) which can be operated from the
outside to slant the movable swash plate.
[0085] The control shaft 141 is supported by the pump case 130 in a
rotatable manner around the axis line, and the movable swash plate
is slanted in accordance with the rotation of the control shaft 141
about the axis line.
[0086] Namely, the control shaft 141 is supported by the pump case
130 in a rotatable manner around the axis line, in a state where
its inner end portion is operatively connected to the movable swash
plate and its outer end portion can be operated from the
outside.
[0087] Further, the outer end portion of the control shaft 141 is
operatively connected to a speed-changing operation member 22 (see
FIG. 3) such as a speed-changing pedal positioned in a vicinity of
the driver's sheet 20, so that the control shaft 141 is rotated
about the axis line in accordance with a manual operation on the
speed-changing operation member 22.
[0088] In the present embodiment, the movable swash plate is
configured so that it can be slanted in both a forward direction
and a rearward direction across a neutral position.
[0089] Namely, when the speed-changing operation member 22 is
operated in a forward side and a rearward side, the control shaft
141 is rotated in one direction and the other direction about the
axis line, thereby causing the movable swash plate to be slanted in
the forward and rearward directions.
[0090] Further, in the present embodiment, the speed-changing
operation member 22 is structured to be of a seesaw-pedal type, but
it can be of a two-pedal type including a dedicated forward pedal
and a dedicated rearward pedal.
[0091] As illustrated in FIG. 3, the pump case 130 is formed with
various fluid channels including a pair of pump-side hydraulic
fluid channels 211 which form portions of the pair of first and
second hydraulic fluid lines 200(1) and 200(2).
[0092] More specifically, as illustrated in FIG. 1, the pump case
130 includes a hollow-shaped pump-side case main body 131 with an
opening having a size that allows the hydraulic pump main body 110
to pass therethrough, and a pump-side port block 132 detachably
coupled to the pump case main body 131 in such a way as to close
the opening in a liquid-tight manner, wherein the fluid channels
are formed in the pump-side port block 132.
[0093] As illustrated in FIG. 3, the pair of pump-side hydraulic
fluid channels 211 include a first pump-side hydraulic fluid
channel 211(1) which experiences a higher pressure at a time of a
forward movement of the vehicle and a second pump-side hydraulic
fluid channel 211(2) which experiences a higher pressure at a time
of a rearward movement of the vehicle.
[0094] The first pump-side hydraulic fluid channel 211(1) has a
first end fluidly connected to the hydraulic pump main body 110
through a first kidney port opened to a contacting surface of the
pump-side port block 132 to which the hydraulic pump main body 110
contacts in a rotatable manner, and a second end opened to an outer
surface of the pump-side port block 132 to form a first pump-side
hydraulic fluid port 212(1).
[0095] Similarly, the second pump-side hydraulic fluid channel
211(2) has a first end fluidly connected to the hydraulic pump main
body 110 through a second kidney port opened to the contacting
surface of the pump-side port block 132 to which the hydraulic pump
main body 110 contacts in a rotatable manner and a second end
opened to the outer surface of the pump-side port block 132 to form
a second pump-side hydraulic fluid port 212(2).
[0096] A pair of first and second pump-side hydraulic fluid
conduits 213(1), 213(2) which form portions of the pair of first
and second hydraulic fluid lines 200(1) and 200(2) are fluidly
connected to the first and second pump-side hydraulic fluid ports
212(1) and 212(2), respectively.
[0097] Further, in the present embodiment, the working vehicle 1A
includes the pair of wheel motor devices 300A(1), 300A(2) for
driving the pair of driving wheels 50(1), 50(2), respectively, as
described above, and the hydraulic motor main bodies 410 in the
pair of wheel motor devices 300A(1) and 300A(2) are fluidly
connected in parallel to the single hydraulic pump main body
110.
[0098] More specifically, the hydraulic motor main bodies 410 in
the pair of wheel motor devices 300A(1) and 300A(2) are fluidly
connected to each other through a first motor-side hydraulic fluid
conduit 214(1) which experiences a higher pressure at a time of the
forward movement of the vehicle and a second motor-side hydraulic
fluid conduit 214(2) which experiences a higher pressure at a time
of the rearward movement of the vehicle, as illustrated in FIG.
3.
[0099] The first and second pump-side hydraulic fluid conduits
213(1), 213(2) are fluidly connected to the first and second
motor-side hydraulic fluid conduits 214(1), 214(2),
respectively.
[0100] Further, as illustrated in FIG. 3, the pump-side port block
132 is formed with a charge fluid channel 220 for replenishing the
pair of first and second hydraulic fluid lines 200(1), 200(2) with
a hydraulic fluid.
[0101] The charge fluid channel 220 has a first end fluidly
connected to a hydraulic pressure source and second ends fluidly
connected to the pair of first and second pump-side hydraulic fluid
channels 211(1), 211(2) through first and second check valves
229(1), 229(2), respectively.
[0102] In the present embodiment, as illustrated in FIG. 3, the
hydraulic pump unit 100 further includes an auxiliary pump main
body 150 which functions as the hydraulic pressure source.
[0103] The auxiliary pump main body 150 is driven directly or
indirectly by the pump shaft 120.
[0104] The auxiliary pump main body 150 has a suction side fluidly
connected to a fluid source such as a fluid tank 90 and a discharge
side fluidly connected to the charge fluid channel 220.
[0105] More specifically, as illustrated in FIG. 3, the pump-side
port block 132 is formed with a suction fluid channel 230 having a
first end opened to the outer surface of the pump-side port block
132 to form a suction port 231 and a second end fluidly connected
to the suction side of the auxiliary pump main body 150, and a
discharge fluid channel 240 having a first end fluidly connected to
the discharge side of the auxiliary pump main body 150 and a second
end fluidly connected to the charge fluid channel 220.
[0106] The suction fluid channel 230 is fluidly connected to the
fluid source through a suction conduit 232 connected to the suction
port 231. In FIG. 3, there are shown a filter 235 inserted in the
suction conduit, and a drain conduit 239 for returning the fluid
stored in the pump case 130 to the fluid source.
[0107] Further, as illustrated in FIG. 3, the pump case 130 is
formed with a charge-pressure setting fluid channel 250 in which a
relief valve 255 for setting the hydraulic pressure in the charge
fluid channel 220 is inserted.
[0108] The charge-pressure setting fluid channel 250 has a first
end fluidly connected to the suction fluid channel 240 or the
charge fluid channel 220 and a second end fluidly connected to the
suction fluid channel 230.
[0109] Further, the relief valve 255 is inserted in the
charge-pressure setting fluid channel 250, in such a manner that
its primary side is oriented to the suction fluid channel 240 or
the charge fluid channel 220 and the relieved fluid from the relief
valve 255 is returned to the suction fluid channel 230.
[0110] Further, as illustrated in FIG. 3, the pump-side port block
132 is formed with a bypass fluid channel 260 for communicating the
first and second pump-side hydraulic fluid channels 211(1) and
211(2) to each other, and a bypass valve 265 for selectively
switching between the communication state and the shutoff state of
the bypass fluid channel 260.
[0111] By providing the bypass fluid channel 260 and the bypass
valve 265, it is possible to effectively prevent the occurrence of
a pressure difference between the pair of first and second
hydraulic fluid lines 200(1), 200(2) at a time when the working
vehicle 1A is forcibly towed in the event of failures of the
driving power source 30, the HST or the like, thereby allowing the
left and right hydraulic motor main bodies 410 for driving the
first and second driving wheels 50(1), 50(2), respectively, to run
at idle when forcibly towing.
[0112] Hereinafter, the wheel motor devices 300A will be
described.
[0113] FIG. 4 illustrates a vertical cross-sectional view of the
wheel motor device 300A(1) (hereinafter, referred to as a first
wheel motor device) for driving one of the pair of driving wheels
50(1) and 50(2) (hereinafter, referred to as a first driving wheel
(50(1)).
[0114] Further, FIG. 5 illustrates an end view of the first wheel
motor device 300A(1) taken along the line V-V in FIG. 4.
[0115] Further, the wheel motor device 300A(2) (hereinafter,
referred to as a second wheel motor device) for driving the other
one of the pair of driving wheels 50(1) and 50(2) (hereinafter,
referred to as a second driving wheel 50(2)) has the same structure
as that of the first wheel motor device 300A(1), and the respective
wheel motor devices are symmetrically mounted with respect to the
pair of main frames 11.
[0116] As illustrated in FIG. 4, the first wheel motor device
300A(1) includes a hydraulic motor unit 400 including the hydraulic
motor main body 410 which forms the HST in cooperation with the
hydraulic pump main body 110, a speed-reduction gear unit 500
including a speed-reduction gear mechanism 510 for reducing the
speed of the rotational power output from the hydraulic motor main
body 410, and a first output member 350(1) for outputting, to the
first driving wheel 50(1), the rotational power whose speed has
been reduced by the speed-reduction gear mechanism 510.
[0117] As illustrated in FIG. 4, the hydraulic motor unit 400
includes a motor shaft 420 which supports the hydraulic motor main
body 410 in a relatively non-rotatable manner, and a motor case 430
which supports the motor shaft 420 in a rotatable manner about the
axis line and also accommodates the hydraulic motor main body 410,
in addition to the hydraulic motor main body 410.
[0118] The hydraulic motor main body 410 includes a motor-side
cylinder block 411 supported by the motor shaft 420 in a relatively
non-rotatable manner, and plural motor-side pistons 412
accommodated in the motor-side cylinder block 411 in a relatively
non-rotatable manner around the axis line of the motor shaft and in
a reciprocating manner along the axis line.
[0119] As described above, in the present embodiment, the hydraulic
motor main bodies 410 are of a fixed displacement type.
[0120] Accordingly, the hydraulic motor unit 400 includes a fixed
swash plate 440, in addition to the components.
[0121] The motor case 430 is coupled directly or indirectly to one
of the pair of main frames 11.
[0122] In the present embodiment, as illustrated in FIG. 1 and FIG.
2, the vehicle frame 10 has a pair of mounting frames 15 extending
downwards from the pair of main frames 11 such that their plate
surfaces are faced to the pair of driving wheels 50(1), 50(2), and
the motor case 430 is coupled to the corresponding one of the
mounting frames 15.
[0123] Preferably, the pair of mounting frames 15 are coupled to
each other at their lower end portions through a reinforcing frame
16, as illustrated in FIGS. 1 and 2. This structure can increase
the rigidity of the vehicle frame 10.
[0124] Further, in the structure where the pair of mounting frames
15 are coupled to each other at their lower end portions through
the reinforcing frame 16, the discharge duct 70 is passed through
the space defined by the cross member 12, the pair of main frames
11, the pair of mounting frames 15 and the reinforcing frame 16, as
illustrated in FIG. 2.
[0125] As illustrated in FIG. 3, the motor case 430 is formed with
a pair of motor-side hydraulic fluid channels 215 which form
portions of the pair of first and second hydraulic fluid lines
200(1) and 200(2).
[0126] More specifically, as illustrated in FIG. 4 and FIG. 5, the
motor case 430 has a hollow-shaped motor case main body 431 with an
opening having a size that allows the hydraulic motor main body 410
to pass therethrough, and a motor-side port block 432 detachably
coupled to the motor case main body 431 in such a way as to close
the opening in a liquid-tight manner, wherein the pair of
motor-side hydraulic fluid channels 215 are formed in the
motor-side port block 432.
[0127] In FIG. 5, there are shown mounting holes 435 for coupling
the motor case 430 to the mounting frame 15, and coupling holes 436
for coupling the motor case main body 431 and the motor-side port
block 432 to each other.
[0128] The pair of motor-side hydraulic fluid channels 215 include
a first motor-side hydraulic fluid channel 215(1) which experiences
a higher pressure at a time of the forward movement of the vehicle
and a second motor-side hydraulic fluid channel 215(2) which
experiences a higher pressure at a time of the rearward movement of
the vehicle.
[0129] The first motor-side hydraulic fluid channel 215(1) has a
first end opened to the outer surface of the motor-side port block
to form a first motor-side hydraulic fluid port 216(1) and a second
end fluidly connected to the hydraulic motor main body 410 through
a first kidney port opened to a contacting surface of the
motor-side port block 432 to which the hydraulic motor main body
410 contacts in a rotatable manner.
[0130] Similarly, the second motor-side hydraulic fluid channel
215(2) has a first end opened to the outer surface of the
motor-side port block 432 to form a second motor-side hydraulic
fluid port 216(2) and a second end fluidly connected to the
hydraulic motor main body 410 through a second kidney port opened
to the contacting surface of the motor-side port block 432 to which
the hydraulic motor main body 410 contacts in a rotatable
manner.
[0131] As described above, in the present embodiment, the hydraulic
motor main body 410 in the first motor device 300A(1) and the
hydraulic motor main body 410 in the second motor device 300A(2)
are fluidly connected to the single hydraulic pump main body 110 in
such a manner that they are parallel with respect to the hydraulic
pump main body 110.
[0132] Namely, as illustrated in FIG. 3, the first motor-side
hydraulic fluid ports 216(1) in the first and second wheel motor
devices 300(1), 300A(2) are fluidly connected to each other through
the first motor-side hydraulic fluid conduit 214(1) and, also, the
second motor-side hydraulic fluid ports 216(2) in the first and
second wheel motor devices 300(1), 300A(2) are fluidly connected to
each other through the second motor-side hydraulic fluid conduit
214(2).
[0133] Further, the first and second motor-side conduits 214(1),
214(2) are fluidly connected to the first and second pump-side
hydraulic fluid conduits 213(1), 213(2), respectively.
[0134] As illustrated in FIG. 4, the motor case main body 431 is
placed such that the opening is orientated inwards in the
vehicle-widthwise direction.
[0135] More specifically, the motor case main body 431 includes a
hollow peripheral wall 431a extending in the direction of the
rotational axis of the hydraulic motor main body 410 in such a way
as to surround the hydraulic motor main body 410, and an end wall
431b which closes the end portion of the peripheral wall 431a on a
side closer to the corresponding first driving wheel 50(1), wherein
the end portion of the peripheral wall 431a on a side away from the
first driving wheel 50(1) forms the opening.
[0136] Further, the motor-side port block 432 is detachably coupled
to the end portion of the motor case main body 431 on a side away
from the first driving wheel 50(1) in such a way as to close the
opening.
[0137] By making an arrangement that the motor-side port block 432,
to which the first and second motor-side hydraulic fluid conduits
214(1), 214(2) are connected, is positioned on a side away from the
first driving wheel 50(1) with the motor case main body 431 as a
reference, as described above, it is possible to insert the motor
case main body 431 and/or a gear case 530 coupled to the motor case
main body 431, which will be described later, into the wheel 55 of
the corresponding first driving wheel 50(1), as much as possible
(see FIG. 4).
[0138] Accordingly, it is possible to expand the free space between
the first wheel motor device 300A(1) for driving the first driving
wheel 50(1) and the second wheel motor device 300A(2) for driving
the second driving wheel 50(2), as much as possible.
[0139] Preferably, as illustrated in FIG. 4, the motor-side port
block 432 may be formed with a cylindrical protrusion 432a at the
surface on a side opposite from the side to which the motor case
main body 431 is mounted, and the protrusion 432a can be inserted
into a circular hole 15a formed in the mounting frame 15 to perform
positioning the motor case 430.
[0140] The motor shaft 420 is supported in a rotatable manner
around the axis line by the motor-side port block 432, the end wall
431b of the motor case main body 431 and a gear case 530 which will
be described later, in a state of being substantially parallel to
the rotational axis line R of the corresponding first driving wheel
50(1), as illustrated in FIG. 4.
[0141] More specifically, as illustrated in FIG. 4, an end portion
of the motor shaft 420 which is closer to the corresponding first
driving wheel 50(1) is penetrated through the end wall 431b and is
extended into a gear space 530S which will be described later,
thereby forming an output end portion for outputting rotational
power to the speed-reduction gear mechanism 510.
[0142] The speed-reduction gear unit 500 includes the gear case 530
which accommodates the speed-reduction gear mechanism 510 and which
supports the first output member 350 in a rotatable manner around
the axis line, in addition to the speed-reduction gear mechanism
510.
[0143] The gear case 530 is coupled to the motor case 430 in such a
way as to form a casing of the wheel motor device 300A(1) in
cooperation with the motor case 430.
[0144] In the present embodiment, the gear case 530 includes an
inner-side case body 531 formed integrally with the motor case 430,
and an outer-side case body 532 detachably coupled to the
inner-side case body 531.
[0145] More specifically, as illustrated in FIG. 4, the end wall
431b of the motor case main body 431 has an extended wall 431c
extending in the direction orthogonal to the motor shaft 420, and
the extended wall 431c forms the inner-side case body 531.
[0146] As a matter of cause, the inner-side case body 531 can be
formed separately from the motor case main body 431 and can be
coupled to the motor case main body 431.
[0147] As illustrated in FIG. 4, the outer-side case body 532 is
detachably coupled to the side of the inner-side case body 531
which is closer to the first driving wheel, in such a way as to
define the gear space 530S for accommodating the speed-reduction
gear mechanism 510 between the outer-side case body 532 and the
inner-side case body 531.
[0148] The speed-reduction gear mechanism 510 is configured so as
to reduce the speed of the rotational power from the motor shaft
420 and transmit it to the first output portion 350(1).
[0149] In the present embodiment, as illustrated in FIG. 4, the
speed-reduction gear mechanism 510 includes a driving-side gear 511
with a smaller diameter which is provided on the output end portion
of the motor shaft 420, and an output gear 512 with a larger
diameter which is provided on the first output member 350(1) in a
state of being engaged with the driving-side gear 511.
[0150] In the present embodiment, as illustrated in FIG. 4, the
first output member 350(1) is formed to be an output shaft.
[0151] More specifically, the first output member 350(1) is
supported by the gear case 530 in a rotatable manner around the
axis line in a state of being positioned coaxially with the
rotational axis line R of the corresponding first driving wheel
50(1), and the end portion of the first output member 350(1) on a
side closer to the first driving wheel 50(1) is extended outwards
and is coupled to the wheel 55 of the first driving wheel
50(1).
[0152] Further, in the present embodiment, the first and second
wheel motor devices 300A(1), 300A(2) are mounted to the working
vehicle in such a manner that they drive the non-steering wheels
(the rear wheels in the illustrated embodiment), but the present
invention is not limited to this embodiment, as a matter of
cause.
[0153] For example, there may be provided steering frames (not
illustrated) which are respectively coupled to the left and right
sides of the vehicle frame 10 through kingpins such that they can
be steered and, also, the first and second wheel motor devices
300A(1), 300A(2) may be mounted to the left and right steering
frames for driving the steering wheels. With this structure, the
first and second wheel motor devices 300A(1), 300A(2) at the left
and right sides are steered in synchronization with each other
through a tie rod mounted to the gear cases 530 or the steering
frames in the wheel motor devices 300A(1), 300A(2).
[0154] Further, while, in the present embodiment, the hydraulic
motor main bodes 410 in the first and second wheel motor devices
300A(1), 300A(2) are fluidly connected in parallel with respect to
the single hydraulic pump main body 10 as described above, instead
of this structure, the working vehicle may be provided with a pair
of hydraulic pump main bodies 110 and, also, the hydraulic motor
main bodies 410 in the first and second wheel motor devices 300A(1)
and 300A(2) may be individually and fluidly connected to the pair
of hydraulic pump main bodies 110.
[0155] As illustrated in FIG. 3 to FIG. 5, the wheel motor device
300A(1) includes a brake mechanism 600 for operatively and
selectively applying a braking force to the first output member
350(1), in addition to the components.
[0156] As illustrated in FIG. 4 and the like, the brake mechanism
600 includes a brake shaft 610 supported by the casing, a
speed-increasing gear mechanism 620 for increasing the rotational
power from the first output member 350(1) and operatively
transmitting it to the brake shaft 600, and a brake unit 630 for
selectively applying a braking force to the brake shaft 610.
[0157] The wheel motor device 300A(1) with the braking mechanism
600 can offer the following effects.
[0158] Namely, the brake mechanism 600 is configured so as to apply
the braking force to the brake shaft 610 which has a rotational
speed increased by the speed-increasing gear mechanism 620 so as to
be higher than that of the first output member 350(1).
[0159] Accordingly, it is possible to reduce the brake capacity
required for the brake mechanism 600, thereby enabling reduction of
the size of the brake mechanism 600.
[0160] Further, the brake shaft 610 to which the braking force is
operatively applied is independent of the transmission path for
transmitting the rotational power from the motor shaft 420 to the
first output member 350(1) through the speed-reduction gear
mechanism 510. The configuration allows the brake shaft 610 to be
placed at an arbitrary position, independently of the positions at
which the motor shaft 420, the speed-reduction gear mechanism 510
and the first output member 350(1) are installed, thereby
increasing the degree of freedom in designing the brake mechanism
60.
[0161] As illustrated in FIG. 4, the brake shaft 610 is provided
with a driven-side gear 621 with a smaller diameter which engages
with the output gear 512.
[0162] In this structure, the output gear 512 and the driven-side
gear 621 form the speed-increasing gear mechanism 620.
[0163] In the present embodiment, as illustrated in FIG. 4 and FIG.
5, the brake shaft 610 is supported by the gear case 530 in a
rotatable manner around the axis line, in a state where its end
portion on a side away from the first driving wheel 50(1) is
extended outwards and where it is substantially parallel to the
rotational axis line R of the first driving wheel 50(1), at a
position displaced from the motor shaft 420 about the rotational
axis line R of the first driving wheel 50(1).
[0164] Further, the brake unit 630 has a brake disk 631 supported
by the outwardly-extending end portion of the brake shaft 610 in a
relatively non-rotatable manner, and is configured so as to
selectively apply the braking force to the brake disk 631 on the
basis of an operation from the outside.
[0165] With this structure, it is possible to effectively prevent
the free space between the pair of driving wheels 50(1), 50(2) from
being reduced due to the provision of the brake mechanism 600.
[0166] Namely, as illustrated in FIG. 4, with the above-described
structure, it is possible to position the brake unit 630 at the
same position as the hydraulic motor main body 410 with respect to
the rotational axis line R of the first driving wheel 50(1) (in the
vehicle-widthwise direction).
[0167] Accordingly, it is possible to prevent the wheel motor
device 300A(1) from being expanded in the direction of the
rotational axis line R of the first driving wheel 50(1) due to the
provision of the brake mechanism 600, thereby ensuring the free
space between the pair of driving wheels 50(1), 50(2) as much as
possible.
[0168] As illustrated in FIGS. 4 and 5, the brake unit 630 includes
a mounting stay 632 detachably supported on the end surface of the
gear case 530 on a side opposite from the first driving wheel 50(1)
(the outer surface of the inner-side case body 531, in the present
embodiment), a brake operation shaft 633 supported by the mounting
stay 632 in a rotatable manner around the axis line in a state of
being substantially parallel to the disk surface of the brake disk
631, and a push-side brake pad 634 supported by the brake operation
shaft 633 in such a way as to contact with or separate from the
brake disk 631 in accordance with the rotation of the brake
operation shaft 633 about the axis line, in addition to the brake
disk 631.
[0169] More specifically, as illustrated in FIG. 4, the brake
operation shaft 633 has a first end portion 633a having a
non-circular cross-sectional shape, wherein the push-side brake pad
634 is supported by the first end portion 633a.
[0170] As illustrated in FIGS. 4 and 5, the brake operation shaft
633 is supported by the mounting stay 632 such that the first end
portion 633a overlaps with the brake disk 631 as viewed along the
rotational axis line of the brake disk 631.
[0171] The brake operation shaft 633 is operatively connected to a
brake operation member (not illustrated) provided near the driving
seat 20, through, for example, a link mechanism including a
connecting arm 636 coupled to the brake operation shaft 633 in a
relatively non-rotatable manner around the axis line of the brake
operation shaft 633 (see FIGS. 4 and 5).
[0172] In the present embodiment, the first end portion 633a of the
brake operation shaft 633 is formed with a concave portion at the
outer surface which is faced to the brake disk 631, and the
push-side brake pad 634 is placed within the concave portion.
[0173] In the present embodiment, the brake disk 631 is supported
by the brake shaft 610 in a movable manner along the axis line, in
a state of being rotated along with the brake shaft 610 around the
axis line.
[0174] In order to effectively making it possible to apply a
braking force to the brake disk 631 having the above-described
structure, the brake unit 600 includes a fixed-side brake pad 635
detachably supported by the gear case 530, such that the fixed-side
brake pad 635 is faced to the push-side brake pad 634 across the
brake disk 631, as illustrated in FIG. 4.
[0175] While, in the present embodiment, the disk-brake type
mechanism having the above-described structure is employed as the
brake mechanism 60, instead of this mechanism, it is also possible
to employ an internal-expanding drum brake type mechanism or a
band-brake type mechanism.
[0176] Preferably, as illustrated in FIG. 6, the brake shaft 610
which constantly rotates in synchronization with the motor shaft
420 can have splines 611 at a portion away from the corresponding
first driving wheel 50(1) than the brake disk 631.
[0177] With this structure, it is possible to easily connect the
brake shaft 610 in the first wheel motor device 300A(1) for driving
the first driving wheel 50(1) and the brake shaft 610 in the second
wheel motor device 300A(2) for driving the second driving wheel
50(2) to each other in a relatively non-rotatable manner around
their axis lines, thereby making it possible to drive the first and
second driving wheels 50(1), 50(2) in a differential-lock
state.
[0178] Namely, as described above, in the present embodiment, the
hydraulic motor main bodies 410 in the first and second wheel motor
devices 300A(1) and 300A(2) are fluidly connected in parallel with
respect to the hydraulic pump main body 110, and the first and
second driving wheels 50(1), 50(2) are therefore differentially
driven by using hydraulic effect.
[0179] With this structure, in the event that one of the first and
second driving wheels 50(1) and 50(2) falls in a concave portion, a
mud area and the like so that the rotational load on this driving
wheel is extremely reduced, the hydraulic fluid from the hydraulic
pump main body 110 is intensively flowed into the hydraulic motor
main body 410 in the wheel motor device 300A(1) or 300A(2) for
operatively driving this driving wheel. As a result, the hydraulic
fluid is not supplied to the hydraulic motor main body 410 in the
wheel motor device 300A(1) or 300A(2) for operatively driving the
other one of the driving wheels 50(1) and 50(2), which may make it
impossible to move the working vehicle.
[0180] In order to avoid the occurrence of the such a state, in the
present embodiment, the brake shaft 610 in the first wheel motor
device 300A(1) and the brake shaft 610 in the second wheel motor
device 300A(2) could be coupled to each other using the splines 611
such that they are relatively non-rotatable to each other about
their axis lines.
[0181] More specifically, as illustrated in FIG. 6, the brake shaft
610 is provided with a brake-shaft-side coupling 650 which is
relatively non-rotatable about the axis line with respect to the
brake shaft 610 through the splines 611. The brake-shaft-side
coupling 650 has a concave/convex engagement portion at an end
surface on a side opposite from the corresponding first driving
wheel 50(1), the concave/convex portion being opened toward the
other driving wheel or the second driving wheel 50(2).
[0182] Meanwhile, the working vehicle 1A to which the wheel motor
devices 300A(1), 300A(2) are applied is provided with a
differential-lock connecting shaft 660.
[0183] The differential-lock connecting shaft 660 is provided in
the working vehicle 1A, such that it can be selectively positioned
at a differential-lock position that is coaxial with the brake
shaft 610 (see FIG. 6) and at a differential position that is
displaced from the brake shaft 610 (not illustrated).
[0184] The differential-lock connecting shaft 660 is formed with
splines 661 at the opposite ends and is provided with first and
second coupling-shaft-side couplings 670 at one end and the other
end in a relatively non-rotatable manner about the axis line
through the splines 661.
[0185] Each of the first and second coupling-shaft-side couplings
670 has a concave/convex engagement portion opened toward the
corresponding driving wheel.
[0186] The switching between the differential state and the
differential-lock state is performed as follows.
[0187] The differential-lock connecting shaft 660 is positioned at
the differential position, at an initial state.
[0188] At this state, there is realized a differential state where
the first and second driving wheels 50(1), 50(2) are differentially
driven using hydraulic effect.
[0189] On the other hand, in a case where it is necessary to
perform the transition from the differential state to the
differential-lock state, an operator moves the differential-lock
connecting shaft 660 from the differential position to the
differential-lock position illustrated in FIG. 6 and, at this
state, the first and second coupling-shaft-side couplings 670 are
engaged with the brake-shaft-side couplings 650 in the first and
second wheel motor devices 300A(1), 300A(2) in a concave-to-convex
manner.
[0190] Accordingly, the first output members 350(1) in the first
and second wheel motor devices 300A(1) are forcibly and
mechanically coupled to each other, thereby realizing the
differential-lock state where the first and second driving wheels
50(1), 50(2) are forcibly driven at the same speed.
[0191] Preferably, as illustrated in FIG. 6, the differential-lock
connecting shaft 660 may be provided with a biasing member 680 for
biasing at least one of the first and second coupling-shaft-side
couplings 670 to the corresponding brake-shaft-side coupling
650.
[0192] With this structure, it is possible to enhance the
efficiency of the operation for switching between the differential
state and the differential-lock state.
[0193] In the wheel motor device 300A(1) according to the present
embodiment, there is only a single position at which the brake
shaft 610 can be installed (see FIG. 5).
[0194] Namely, in the present embodiment, the brake shaft 610 can
be supported at a single position which is just opposite from the
motor shaft 420 with the rotational axis line of the first output
member 350(1) as a reference (namely, which is displaced by about
180 degree from the motor shaft 420 about the rotational axis line
of the first output member 350(1)). However, instead of this
structure, the brake shaft 610 may be supported at plural positions
about the rotational axis line of the first output member
350(1).
[0195] FIG. 7 illustrates an end view of a wheel motor device 300A'
according to a modified embodiment of the present embodiment,
corresponding to FIG. 5.
[0196] As illustrated in FIG. 7, the wheel motor device 300A'
according to the modified embodiment includes a gear case 530',
instead of the gear case 530.
[0197] The gear case 530' has plural brake-shaft bearing portions
615a, 615b capable of supporting the brake shaft 610 at plural
positions about the rotational axis line of the first output member
350(1) which is positioned coaxially with the rotational axis line
R of the corresponding driving wheel.
[0198] The gear case 530' is also configured so as to be capable of
supporting the mounting stay 632 and the fixed-side brake pad 635,
at plural positions corresponding to the plural brake-shaft bearing
portions 615a, 615b.
[0199] Namely, as illustrated in FIG. 7, the gear case 530'
includes the plural brake-shaft bearing portions 615a, 615b
positioned around the rotational axis line of the first output
member 350(1), and plural mounting stay mounting portions 616a,
616b and plural fixed-side brake-pad mounting portions 617a, 617b
corresponding to the plural brake-shaft bearing portions 615a,
615b.
[0200] By employing the configuration where the brake shaft 610 can
be installed at the plural positions about the axis line of the
first output member 350(1) as described above, it is possible to
enhance the degree of freedom in designing the position at which
the brake mechanism 600 is installed.
[0201] Preferably, the plural brake-shaft bearing portions 615a,
615b capable of supporting the brake shaft 610 include first and
second bearing portions 615a, 615b which are symmetrical to each
other with an imaginary vertical plane VP as a reference, which
passes through the rotation axis line of the first output member
350(1).
[0202] With this structure, in the case where the pair of wheel
motor devices 300A' are employed as a first wheel motor device
300A'(1) for driving the first driving wheel 50(1) and a wheel
motor device 300A'(2) for driving the second driving wheel 50(2),
it is possible to have the brake shafts 610 in the first and second
wheel motor devices 300A'(1), 300A'(2) positioned coaxially to each
other.
[0203] Namely, by arranging the brake shaft 610 in the first wheel
motor device 300A'(1) at one of the first and second bearing
portions 615a, 615b while arranging the brake shaft 610 in the
second wheel motor device 300A'(2) at the other one of the first
and second bearing portions 615a, 615b, it is possible to have the
brake shafts 610 in the first and second wheel motor devices
300A'(1), 300A'(2) positioned coaxially to each other, while
employing wheel motor devices with the same structure as the first
and second wheel motor devices 300A'(1), 300A'(2).
[0204] Further, in the working vehicle 1A where the pair of rear
wheels are formed to be the pair of driving wheels 50(1), 50(2) as
in the present embodiment, the brake shafts 610 preferably may be
supported by bearing portions positioned in the front side of the
vehicle than the rotational axis line of the corresponding driving
wheels 50(1), 50(2), at a state where the wheel motor devices 300A'
are mounted in the working vehicle 1A.
[0205] With this structure, it is possible to effectively prevent
the brake unit 630 from coming into contact with external
obstructions during the rearward movement of the vehicle.
Second Embodiment
[0206] Hereinafter, another embodiment of the wheel motor device
according to the present invention will be described, with
reference to the attached drawings.
[0207] FIGS. 8 and 9 illustrate a schematic side view and a
schematic rear view of a working vehicle 1B to which the wheel
motor device 300B according to the present embodiment is
applied.
[0208] In the figures, the components same as those in the first
embodiment are designated by the same reference characters and
detailed description there of will not be repeated.
[0209] While the wheel motor device 300A according to the first
embodiment is configured so as to output the driving power only to
the corresponding one of the driving wheels (for example, the first
driving wheel 50(1)), the wheel motor device 300B according to the
present embodiment is configured so as to output the driving power
to the corresponding one of the driving wheels (for example, the
first driving wheel 50(1)) and also output the driving power to the
other driving wheel (for example, the second driving wheel
50(2).
[0210] FIGS. 10 and 11 illustrate a vertical cross-sectional view
of the wheel motor device 300B and an end view of the same taken
along the line XI-XI in FIG. 10, respectively.
[0211] As illustrated in FIGS. 10 and 11, the wheel motor device
300B includes a speed-reduction gear unit 500B, instead of the
speed-reduction gear unit 500 in the wheel motor devices 300A
according to the first embodiment, and also includes a second
output member 350(2) for outputting the rotational power to the
other driving wheel (for example, the driving wheel 50(2)) on a
side opposite from the corresponding one driving wheel (for
example, the driving wheel 50(1)) which is close to the wheel motor
device 300B.
[0212] Namely, the wheel motor device 300B includes the hydraulic
motor unit 400, the speed-reduction gear unit 500B, the first
output member 350(1), the second output member 350(2) and the brake
mechanism 600.
[0213] As illustrated in FIG. 10, the speed-reduction gear unit
500B includes a gear case 530B for supporting the first and second
output members 350(1), 350(2) in a rotatable manner around their
axis lines, and a mechanical differential gear mechanism 70
accommodated within the gear case 530B.
[0214] The gear case 530B is coupled to the motor case 430 in such
a way as to form a casing of the wheel motor device 300B in
cooperation with the motor case 430, similarly to the gear case 530
according to the first embodiment.
[0215] The gear case 530B includes an inner-side case body 531B
formed integrally with the motor case 430, and the outer-side case
body 532 detachably coupled to the inner-side case body 531B.
[0216] In the present embodiment, as in the first embodiment, the
extended wall 431c of the motor case main body 431 forms the
inner-side case body 531B. As a matter of cause, the inner-side
case body 531B can be formed separately from the motor case main
body 431.
[0217] The gear case 530B supports the first and second output
members 350(1), 350(2) in such a manner that they are positioned
coaxially to each other and are rotatable around their axis lines
independently to each other.
[0218] Specifically, the first output member 350(1) is supported by
the outer-side case body 532 in a rotatable manner around the axis
line so as to be positioned coaxially with the rotational axis line
R of the corresponding first driving wheel 50(1) in a state where
its inner end is positioned within the gear case 530B and its outer
end is extended outwards to be close to the first driving wheel
50(1).
[0219] Meanwhile, the second output member 350(2) is supported by
the inner-side case body 531B in a rotatable manner around the axis
line so as to be positioned coaxially with the rotational axis line
of the first output member 350(1) in a state where its inner end is
positioned within the gear case 530B so as to face to the inner end
of the first output member 350(1) and its outer end is extended
outwards to be close to the second driving wheel 50(2).
[0220] As illustrated in FIG. 9, the second output member 350(2) is
coupled to a wheel 55 of the second driving wheel 50(2) through a
connecting shaft 360 such that the second output member 350(2)
rotate along with the wheel 55 around the axis line.
[0221] Further, the connecting shaft 360 can be either formed
integrally with the second output shaft 350(2) or formed separately
therefrom, as a matter of cause.
[0222] In the present embodiment, as illustrated in FIG. 9, the
connecting shaft 360 is coupled to a driving axle 56 of the wheel
55 of the second driving wheel 50(2) through a coupling member
365.
[0223] The driving axle 56 of the second driving wheel 50(2) is
supported in a rotatable manner about the axis line through a
bearing bracket 365 coupled to the mounting frames 15, as
illustrated in FIG. 9.
[0224] The differential gear mechanism 70 includes a ring gear 710
placed coaxially with the rotational axis line of the first and
second output members 350(1), 350(2), first and second side bevel
gears 720(1), 720(2) respectively supported on the first and second
output members 350(1), 350(2) in a relatively non-rotatable manner,
a pinion shaft 730 which extends in the direction orthogonal to the
rotational axis line of the first and second output members 350(1),
350(2) and which rotates about the rotational axis line of the
first and second output members 350(1), 350(2) together with the
ring gear 710, and a bevel pinion 740 supported on the pinion shaft
730 in a relatively non-rotatable manner in a state of being
engaged with the first and second side bevel gears 720(1), 720(2),
as illustrated in FIG. 10.
[0225] As illustrated in FIG. 10, the ring gear 710 is engaged with
both the driving-side gear 511 provided on the motor shaft 420 and
the driven-side gear 621 provided on the brake shaft 610.
[0226] Namely, in the present embodiment, the driving-side gear 511
and the ring gear 710 form the speed-reduction gear mechanism 510
and, also, the ring gear 710 and the driven-side gear 621 form the
speed-increasing gear mechanism 620.
[0227] In the present embodiment, it is possible to obtain an
effect of differentially driving the first and second driving
wheels 50(1), 50(2) only by providing one wheel motor device 300B
in a vicinity of one of the first and second driving wheels 50(1),
50(2), in addition to offering the effects of the first
embodiment.
[0228] Preferably, the differential gear mechanism 700 includes a
differential-lock mechanism 750.
[0229] In the present embodiment, as illustrated in FIG. 10 and
FIG. 11, the differential-lock mechanism 750 includes a
differential-lock slider 760 which is rotatable about the
rotational axis line of the first and second output members 350(1),
350(2) together with the ring gear 710 and which is movable in the
direction of the rotational axis line, and a differential-lock fork
770 which is supported by the casing in such a way as to move the
slider member 760 in the direction of the rotational axis line
according to an operation from the outside.
[0230] As illustrated in FIG. 10, the differential-lock slider 760
is supported by one (the second output member 350(2) in the
illustrated embodiment) of the first and second output members
350(1), 350(2) on which one (the second side bevel gear 720(2) in
the illustrated embodiment) of the first and second side bevel
gears 750(1), 750(2) is supported, in such a manner that the slider
760 is relatively rotatable around and movable along the axis line
of the one output member.
[0231] More specifically, the differential-lock slider 760 has a
supported portion 761 supported by the corresponding output member,
a radially-extended portion 762 extending outwards in the radial
direction from the supported portion 761 so as to face to the one
of the side bevel gears, and an axially-extended portion 763
extending in the direction of the rotational axis line from the
radially-extended portion 762 toward the ring gear 710.
[0232] The radially-extended portion 762 is selectively coupled to
the one of the side bevel gears in such a manner that it is rotated
together with the one side bevel gear, according to the position of
the differential-lock slider 760 with respect to the direction
along the rotational axis line.
[0233] More specifically, the radially-extended portion 762 has one
of a concave portion and a convex portion at the surface facing to
the one side bevel gear, and the one side bevel gear has the other
one of the concave portion and the convex portion at the surface
facing to the radially-extended portion 762, so that the concave
portion and the convex portion are selectively engaged with each
other or disengaged from each other according to the position of
the differential-lock slider 760 with respect to the direction of
the rotational axis line.
[0234] As illustrated in FIG. 10, the axially-extended portion 763
is engaged into a slit 715 formed in the ring gear 710, so that the
differential-lock slider 760 rotates together with the ring gear
710 about the rotational axis line of the first and second output
members 350(1), 350(2).
[0235] The differential-lock fork 770 is configured so as to move
the differential-lock slider 760 in the direction along the
rotational axis line on the basis of an operation from the
outside.
[0236] More specifically, the differential-lock fork 770 has
rotational shaft portions 771 which are along the direction
orthogonal to the rotational axis line and which are supported
directly or indirectly by the casing in a rotatable manner around
the axis line, and an engagement portion 772 extending from the
rotational shaft portions 771 such that its free end portion
engages with the differential-lock slider 760.
[0237] In the present embodiment, the differential-lock fork 770
has a pair of rotational shaft portions 771 facing to each other
across the differential-lock slider 760.
[0238] Further, a differential-lock arm 780 is coupled to one of
the pair of rotational shaft portions 771 in a relatively
non-rotatable manner.
[0239] Namely, the differential-lock arm 780 has a supporting shaft
portion 781 supported by the casing in a rotatable manner around
the axis line, and an arm portion 782 coupled to the supporting
shaft portion 781 in such a manner it is positioned outside of the
casing with being relatively non-rotatable with respect to the
supporting shaft portion 781.
[0240] With this structure, one of the pair of rotational shaft
portions 771 is coupled to the supporting shaft portion 781 in a
relatively non-rotatable manner about the axis line.
[0241] The arm portion 782 is operatively connected through a
suitable link mechanism (not illustrated) to a differential-lock
operation member (not illustrated) capable of being manually
operated which is positioned near the driver's seat 20.
[0242] The provision of the differential-lock mechanism 750 makes
it possible to easily switch between the differential state where
the first and second driving wheels 50(1), 50(2) are differentially
driven and a differential-lock state where the first and second
driving wheels 50(1), 50(2) are forcibly driven at the same
speed.
[0243] Further, while, in the present embodiment, the single wheel
motor device 300A is provided with the differential gear mechanism
700 so that the rotational power from the motor shaft 420 is
differentially transmitted to the first and second output members
350(1), 350(2), it is also possible to employ a side clutch or a
side brake which is linked to a steering wheel, or a gear-less
differential mechanism including two bidirectional clutches,
instead of the differential gear mechanism 70.
[0244] While, in the first and second embodiments, the motor case
400 is coupled to the mounting frames 15 at the side surface
opposite from the corresponding driving wheel for mounting the
wheel motor device to the pair of main frames 11 as described above
(see FIGS. 4, 10 and the like), the present invention is not
limited to the embodiments, as a matter of cause.
[0245] FIGS. 12 and 13, respectively, illustrate a vertical
cross-sectional view and an exploded perspective view of a wheel
motor device 300C mounted to the pair of main frames 11 through
another mounting structure, according to a modified embodiment of
the present invention.
[0246] In FIG. 12 and FIG. 13, the components same as those of the
first and second embodiments are designated by the same reference
characters and description thereof will not be repeated.
[0247] As illustrated in FIGS. 12 and 13, in the wheel motor device
300C, the motor case main body 431 and the motor-side port block
432 have a first and second frame mount bosses 430a and 430b,
respectively, on their upper surfaces. In the first and second
frame mount bosses 430a and 430b, plural first and second bolt
holes 430c and 430d opened upwards are arranged in the lengthwise
direction of the vehicle.
[0248] Meanwhile, a mounting stay 18 is coupled to an outer side
surface of the corresponding main frame 11.
[0249] The mounting stay 18 has a substantially T-shape in a
cross-section including a vertical portion 18a coupled to the outer
side surface of the corresponding main frame 11 through fastening
members such as bolts and a horizontal portion 18b coupled to the
lower end portion of the vertical portion 18a. The horizontal
portion 18b has such a length in the vehicle widthwise direction as
to straddle both the bosses 430a and 430b.
[0250] The horizontal portion 18b is provided with first and second
through holes 19a and 19b corresponding to the first and second
bolt holes 430c and 430d, and the mounting stay 18 supports the
motor case 430 through plural bolts 19c inserted through the first
and second through holes 19a and 19b and also threadedly inserted
in the first and second bolt holes 430c and 430d.
[0251] As described above, in the wheel motor device 300C, the
first and second bosses 430a, 430b are provided on the motor case
main body 431 and the motor-side port block 432, which enables
effectively accepting bending stresses applied to the wheel motor
device 300C.
[0252] Namely, both the first and second bosses 430a and 430b can
be provided on the upper surface of the motor case main body 431,
but this structure will reduce the interval between the first and
second bosses 430a and 430b, thereby causing larger loads to be
applied to the first and second bosses 430a and 430b.
[0253] On the contrary, the structure illustrated in FIG. 12 and
FIG. 13 can increase the interval between the first and second
bosses 430a and 430b, thereby enabling effectively accepting
bending stresses applied to the wheel motor device 300A.
[0254] Further, with the structure illustrated in FIG. 12 and FIG.
13, the mounting stay 18 and the first and second bosses 430a and
430b have the function of reinforcing the bonding between the motor
case main body 431 and the motor-side port block 432, thereby
effectively preventing the hydraulic fluid from being leaked
through the bonding portion between the motor case main body 431
and the motor-side port block 432.
[0255] FIG. 14 illustrates a vertical cross-sectional view of a
wheel motor device 300D according to another modified embodiment of
the present invention.
[0256] In FIG. 14, the components same as those in the
above-explained embodiments and modified embodiment are designated
by the same reference characters and detailed description there of
will not be repeated.
[0257] The wheel motor device 300D is mainly different from the
wheel motor device 300A according to the first embodiment in that
the hydraulic motor main body 410 is replaced with a hydraulic
motor main body 410D of a radial piston type and in that the
speed-reduction gear mechanism 510 is replaced with a
speed-reduction gear mechanism 510D.
[0258] Specifically, the wheel motor device 300D includes a
hydraulic motor unit 400D including the hydraulic motor main body
410D, a speed-reduction gear unit 500D including the
speed-reduction gear mechanism 510D, and the output member (the
first output member 350(1) in the illustrated embodiment) for
outputting, to the corresponding driving wheel (the first driving
wheel 50(1) in the illustrated embodiment), the rotational power
whose speed has been reduced by the speed-reduction gear mechanism
510D.
[0259] The hydraulic motor unit 400D includes, as shown in FIG. 14,
the hydraulic motor main body 410D of a radial piston type, the
motor shaft 420 supporting the hydraulic motor main body 410D in a
relatively non-rotatable manner, and a motor case 430D which
supports the motor shaft 420 in a rotatable manner about the axis
line and which accommodates the hydraulic motor main body 410D.
[0260] The hydraulic motor main body 410D includes a cylinder block
411D connected to the motor shaft 420 in a relatively non-rotatable
manner.
[0261] The cylinder block 411D is supported in a rotatable manner
around its axis line on a support shaft 470D, which is provided at
the motor case 430D so as to be positioned coaxially with the motor
shaft 420.
[0262] The cylinder block 411D includes plural cylinder chambers
412 which are disposed around the axis line and each of which
extends in a radial direction so as to have a first end opened to
an inner circumferential surface of the cylinder block 411D that is
in contact with the support shaft 470D and a second end opened to
an outer circumferential surface of the cylinder block 411D.
[0263] The hydraulic motor main body 410D further includes plural
piston members 413D respectively accommodated in the plural
cylinder chambers 412 in a reciprocating manner along a radial
direction with the axis line as a reference.
[0264] In the present modified embodiment, the hydraulic motor main
body 410D further includes plural biasing members 414D that
respectively press the plural piston members 413D radially
outward.
[0265] The end on a radially outward side of the movable range of
the plural piston members 413D is defined by a thrust ring 445D
provided in the motor case 430D.
[0266] Specifically, the cylindrical thrust ring 445D is
accommodated in the motor case 430D so as to surround the cylinder
block 411D. That is, the cylinder block 411D is inserted into the
thrust ring 445D in a state of being supported by the support shaft
470D in a relatively rotatable manner.
[0267] In the present modified embodiment, the thrust ring 445D has
an inner circumferential surface having a substantially circular
shape as viewed along the axis line, and is fixed in an immovable
manner in a state of being eccentric with respect to the cylinder
block 411D.
[0268] The wheel motor device 300D includes the hydraulic motor
main body 410D of a radial piston type as described above, thereby
realizing miniaturization of the wheel motor device 300D in the
vehicle-widthwise direction, in comparison with the wheel motor
device 300 including the hydraulic motor main body 410 of an axial
piston type.
[0269] The motor case 430D is formed with the first motor-side
hydraulic fluid channel 215(1) which experiences a higher pressure
at a time of the forward movement of the vehicle and the second
motor-side hydraulic fluid channel 215(2) which experiences a
higher pressure at a time of the rearward movement of the
vehicle.
[0270] The wheel motor device 300D according to the present
modified embodiment includes the hydraulic motor main body 410D of
a radial piston type, as described above.
[0271] Therefore, the first motor-side hydraulic fluid channel
215(1) has a first end opened to the outer surface of the motor
case 430D to form the first motor-side hydraulic fluid port 216(1)
and second ends branched so as to be fluidly connected to half of
the plural cylinder chambers 412D.
[0272] Similarly, the second motor-side hydraulic fluid channel
215(2) has a first end opened to the outer surface of the motor
case 430D to form the second motor-side hydraulic fluid port 216(2)
and second ends branched so as to be fluidly connected to a
remaining half of the plural cylinder chambers 412D.
[0273] The motor case 430D includes a motor case main body 431D
that surround the hydraulic motor main body 410D and that forms an
opening having a size that allows the hydraulic motor main body
410D to pass therethrough, the thrust ring 445D provided in the
motor case main body 431D through the opening, and a motor-side
port block 432D detachably coupled to the motor case main body 431D
in such a way as to close the opening in a liquid-tight manner.
[0274] In the present modified embodiment, the support shaft 470D
is integrally formed with the motor-side port block 432D, and
therefore, the first and second motor-side hydraulic fluid channels
215(1), 215(2) are formed in the motor-side port block 432D.
[0275] The wheel motor device 300D is supported in a hanged manner
by the corresponding main frame 15 through the mounting stay 18,
similarly to the wheel motor device 300C.
[0276] In the wheel motor device 300D, the first and second bosses
430a, 430b are provided at an upper surface of the motor case main
body 431D, as shown in FIG. 14.
[0277] The speed-reduction gear unit 500D includes the
speed-reduction gear mechanism 510D, and the gear case 530 which
accommodates the speed-reduction gear mechanism 510D and which
supports the first output member 350(1) in a rotatable manner
around the axis line.
[0278] The speed-reduction gear mechanism 510D includes the
driving-side gear 511 with a small diameter, and an output gear
512D with a large diameter which is provided on the first output
member 350(1) so as to be engaged with the driving-side gear
511.
[0279] In the present modified embodiment, the output gear 512D is
embodied by an internal gear.
[0280] The driven-side gear 621 provided at the brake shaft 610 is
also engaged with the output gear 512D in form of the internal
gear.
[0281] In the present modified embodiment, the output gear 512D
that is engaged with the driving-side gear 511 to form the
speed-reduction gear mechanism 510D and that is engaged with the
driven-side gear 621 to form the speed-increasing gear mechanism
620 is embodied by the internal gear, as described above.
[0282] The wheel motor device 300D with the configuration makes it
possible to have the positions of the axis lines of the motor shaft
420 and the brake shaft 610 come close to the position of the axis
line of the output member while sufficiently ensuring a speed
reducing ratio of the speed-reduction gear mechanism 510D and a
speed increasing ratio of the speed-increasing gear mechanism 620,
thereby realizing miniaturization of the wheel motor device 300D in
a radial direction.
[0283] Finally, a wheel motor device 300 E will be described.
[0284] Although the wheel motor device 300E is inferior to the
wheel motor devices according to the above explained embodiments
and modified embodiments in terms of the degree of freedom in
designing the brake mechanism 600, it could ensure the free space
at the center in the vehicle widthwise direction as much as
possible while realizing miniaturization of the brake mechanism 600
as much as possible.
[0285] FIG. 15 illustrates a vertical cross-sectional view of the
wheel motor device 300E.
[0286] In FIG. 15, the components same as those in the
above-explained embodiments and modified embodiment are designated
by the same reference characters and detailed description there of
will not be repeated.
[0287] The wheel motor device 300E is different from the wheel
motor devices according to the above-explained embodiments and
modified embodiments in that the brake mechanism 600 is configured
so as to apply the braking force to the motor shaft 420.
[0288] Specifically, the wheel motor device 300E includes the
hydraulic motor unit 400, a speed-reduction gear unit 500E
including the speed-reduction gear mechanism 510, and the output
member (the first output member 350(1) in the illustrated
embodiment) for outputting, to the corresponding driving wheel (the
first driving wheel 50(1) in the illustrated embodiment), the
rotational power whose speed has been reduced by the
speed-reduction gear mechanism 510.
[0289] The speed-reduction gear unit 500E includes the
speed-reduction gear mechanism 510, and a gear case 530E which
accommodates the speed-reduction gear mechanism 510 and which
supports the first output member 350 (1) in a rotatable manner
around the axis line.
[0290] The gear case 530E includes an inner-side case body 531E
connected to the motor case 430, and an outer-side case body 532E
detachably coupled to the inner-side case body 531E so as to form
the gear space 530S in cooperation therewith.
[0291] As in the above-explained embodiments and modified
embodiments of the present invention, the inner-side case body 531E
is integrally formed with the motor case 430.
[0292] The outer-side case body 532E is formed with a bearing hole
535E allowing a first end 420a of the motor shaft 420 on a side
close to the corresponding driving wheel to extend outward, as
shown in FIG. 15.
[0293] Specifically, in the wheel motor device 300E, the motor
shaft 420 has the first end 420a on a side close to the
corresponding driving wheel that extends outward from the
outer-side case body 532E. The brake mechanism 600 is provided at
an outer surface of the outer-side case body 552e on a side close
to the corresponding driving wheel so as to apply the braking force
to the first end 420a of the motor shaft 420.
[0294] The thus configured wheel motor device 300E makes it
possible to ensure the free space between the pair of wheel motor
devices 300E larger than a wheel motor device 300F (see FIG. 16) in
which the brake mechanism 300 is positioned between the hydraulic
motor unit 400 and the speed-reduction gear unit 500 in the vehicle
widthwise direction.
[0295] In the wheel motor device 300E, the brake mechanism 600 is
preferably disposed within the wheel 55, as shown in FIG. 15.
[0296] According to the preferable arrangement, it is possible to
have the wheel motor device 300E come close to the corresponding
driving wheel in the vehicle widthwise direction as much as
possible, thereby widening the free space as much as possible.
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