U.S. patent application number 11/910808 was filed with the patent office on 2009-03-26 for drum rotating apparatus for use on construction machines.
Invention is credited to Yoshiomi Jojima, Takeshi Obata, Masami Ochiai, Tadahiro Shimozono, Atsushi Tanaka, Nobuo Uzawa.
Application Number | 20090078528 11/910808 |
Document ID | / |
Family ID | 37708833 |
Filed Date | 2009-03-26 |
United States Patent
Application |
20090078528 |
Kind Code |
A1 |
Uzawa; Nobuo ; et
al. |
March 26, 2009 |
DRUM ROTATING APPARATUS FOR USE ON CONSTRUCTION MACHINES
Abstract
A support member which is securely fixed to a truck frame is
constituted by a tubular body portion and a lid portion. A couple
of dry electromagnetic brakes are located in a brake accommodation
room within the tubular body portion. The support member is
assembled with an electric motor. A drum member which accommodates
a planetary reduction gear mechanism is rotatably mounted on the
outer periphery of the support member through bearings. A floating
seal is provided between the support member and the drum member,
and a seal ring (45) is provided between an axial bore in the
support member and a coupling shaft. Thus, the two dry
electromagnetic brakes are accommodated in the support member,
safely shielded from lubricant oil.
Inventors: |
Uzawa; Nobuo; (Chiba,
JP) ; Tanaka; Atsushi; (Ibaraki, JP) ; Ochiai;
Masami; (Kanagawa, JP) ; Shimozono; Tadahiro;
(Chiba, JP) ; Jojima; Yoshiomi; (Chiba, JP)
; Obata; Takeshi; (Chiba, JP) |
Correspondence
Address: |
MATTINGLY, STANGER, MALUR & BRUNDIDGE, P.C.
1800 DIAGONAL ROAD, SUITE 370
ALEXANDRIA
VA
22314
US
|
Family ID: |
37708833 |
Appl. No.: |
11/910808 |
Filed: |
July 28, 2006 |
PCT Filed: |
July 28, 2006 |
PCT NO: |
PCT/JP2006/315442 |
371 Date: |
October 5, 2007 |
Current U.S.
Class: |
192/12D |
Current CPC
Class: |
Y02T 10/641 20130101;
E02F 9/02 20130101; B60L 2220/44 20130101; B60K 7/0007 20130101;
Y02T 10/64 20130101; H02K 7/116 20130101; B60L 2200/40 20130101;
B62D 55/125 20130101; B60K 2007/0038 20130101; B60K 2007/0092
20130101; B60K 17/046 20130101; H02K 7/1025 20130101; F16D 2121/22
20130101; B60Y 2200/41 20130101 |
Class at
Publication: |
192/12.D |
International
Class: |
E02F 9/02 20060101
E02F009/02 |
Foreign Application Data
Date |
Code |
Application Number |
Aug 1, 2005 |
JP |
2005-223163 |
Claims
1. A drum rotating apparatus for use on a construction machine,
characterized by the provision of: a support member of a tubular
shape, open at one axial end and closed with a lid portion at the
other axial end thereof, said support member being securely fixed
on a basis of a construction machine; an electric motor located at
one axial end of said support member, said electric motor having an
output shaft extended axially toward said support member and being
connected to an external power supply to rotate said output shaft;
a drum member of a tubular shape, open at one axial end and closed
at the other axial end thereof, said drum member being rotatably
supported on outer periphery of said support member at one axial
end through bearings; a reduction gear mechanism immersed in a
lubricant oil within said drum member, said reduction gear
mechanism having a single or multiple reduction stages to rotate
said drum member at a reduced speed; a coupling shaft extended
axially in and through said support member, said coupling shaft
having one axial end connected to said output shaft of said
electric motor and the other axial end rotatably supported in said
lid portion of said support member and coupled with said reduction
gear mechanism; a negative type dry electromagnetic brake
accommodated in said support member to apply the brakes to said
coupling shaft when said electric motor is at rest and take off the
brakes to said coupling shaft when said electric motor is in
rotation; a first seal member forming a liquid tight seal between
said support member and an opening at one axial end of said drum
member; and a second seal member forming a liquid tight seal
between said lid portion of said support member and said coupling
shaft; and a couple of said dry electromagnetic brakes are provided
in spaced positions in the axial direction of said coupling
shaft.
2. (canceled)
3. A drum rotating apparatus for use on a construction machine as
defined in claim 1, wherein a couple of said dry electromagnetic
brakes are adapted to be assembled into said support member
commonly in the same direction toward said lid portion through and
from the side of an opening at one axial end of said support
member.
4. A drum rotating apparatus for use on a construction machine as
defined in claim 1, wherein said coupling shaft is composed of a
coupling having one axial end connected to said output shaft of
said electric motor and provided with a spline on the outer
periphery thereof, and an input shaft having one axial end thereof
connected to said coupling and the other axial end connected to
said reduction gear mechanism; said dry electromagnetic brake being
comprised of a rotatable disc meshed with said spline of said
coupling for rotation therewith, an non-rotatable disc adapted to
be brought into and out of frictional engagement with said
rotatable disc by a displacement in an axial direction of said
coupling, and an electromagnetic coil excited by a power supply
from outside to disengage said non-rotatable disc from said
rotatable disc.
5. A drum rotating apparatus for use on a construction machine as
defined in claim 1, further comprising a connector accommodation
room provided upward of said dry electromagnetic brake within said
support member fixed on said basis, and a connector mounted in said
connector accommodation room to connect external wiring to internal
wiring leading to said dry electromagnetic brake.
6. A drum rotating apparatus for use on a construction machine as
defined in claim 1, wherein said basis constitutes a truck frame of
a crawler type lower structure of said construction machine, said
drum member is provided with a sprocket fixedly on the outer
periphery thereof for meshing engagement with a crawler belt, and
both of said electric motor and said reduction gear mechanism are
located within a width of said crawler belt in transverse
direction.
Description
TECHNICAL FIELD
[0001] This invention relates to a drum rotating apparatus
particularly suitable for use in a construction machine, for
example, a vehicle drive unit for a hydraulic excavator, a
hydraulic crane or a rope winch drum.
BACKGROUND ART
[0002] Generally, vehicle drive units of construction machines such
as hydraulic excavators, wheel loaders and the like employ a drum
rotating apparatus for rotating a drum member on which a sprocket
is mounted, for driving a crawler belt or for rotating a drum
member on which a vehicle wheel is mounted. Also, a drum rotating
apparatus is used on a rope winch which is mounted, for example, on
a hydraulic crane for winding and unwinding a rope by rotating a
drum member (e.g., see, for example, Japanese Patent Laid-Open No.
2000-9017, H1-153840 and S60-183498).
[0003] In this instant, the prior art drum rotating apparatuses are
largely constituted by a hydraulic motor serving as a drive source,
a reducing mechanism which is located on the inner peripheral side
of a drum member for reducing the speed in transmitting rotation of
the hydraulic motor to the drum member, and a coupling shaft which
couples an output shaft of the hydraulic motor with the reducing
mechanism. In the drum rotating apparatus of this sort, a drum
member is rotated with a large torque by reducing the speed of
rotation of a hydraulic motor through a reducing mechanism.
[0004] Further, normally, a drum rotating apparatus of this sort is
provided with a negative type wet multiple disc brake, applying the
brakes to the coupling shaft when the hydraulic motor is at rest
and taking the brakes off when the hydraulic motor is in rotation.
Usually, a wet type multiple disc brake of a compact form is
provided on the inner peripheral side of a drum member along with a
reducing mechanism for compactification of a drum rotating
apparatus as a whole.
[0005] In the above-mentioned prior art, the hydraulic motor which
is provided in the drum rotating apparatus rotate an output shaft
by supplying pressure oil from a hydraulic pump which is driven by
an engine. Therefore, there has been a serious problem of pollution
of environments by exhaust gases emanated from an engine during a
drum rotating apparatus is in operation, in addition to a problem
that a working environment is degraded to a considerable degree by
operational noises of the engine.
[0006] In this regard, there has been developed and in use a drum
rotating apparatus using an electric motor in place of a hydraulic
motor as a drive source. In a drum rotating apparatus of this type,
an electric motor is driven by power supplied from a power source
like a battery, for the purpose of suppressing emissions of exhaust
gases and operational noises (e.g., see, for example Japanese
Patent Laid-Open No. H11-155256).
[0007] In this connection, in the case of a drum rotating apparatus
driven by an electric motor, it is desirable to use a negative type
dry electromagnetic brake instead of a wet multiple disc brake from
the standpoint of effectively use of a power source like a
battery.
[0008] However, in the case of an electric motor-driven drum
rotating apparatus having lubricant oil within a drum member along
with a reducing mechanism, difficulties are encountered in mounting
a negative type dry electromagnetic brake on the inner peripheral
side of a drum in a compact form, in a complete shielded state from
inflammable lubricant oil.
DISCLOSURE OF THE INVENTION
[0009] In view of the above-discussed problems with the prior art,
it is an object of the present invention to provide a drum rotating
apparatus for a construction machine, having a negative type dry
electromagnetic brake accommodated inside of the inner periphery of
a drum member in a compact form and in a shielded state from
lubricant oil.
[0010] (1) According to the present invention, in order to achieve
the above-stated objective, there is provided a drum rotating
apparatus for use on a construction machine, which is characterized
by the provision of:
[0011] a support member of a tubular shape, open at one axial end
and closed with a lid portion at the other axial end thereof, the
support member being securely fixed on a basis of a construction
machine; an electric motor located at one axial end of the support
member, the electric motor having an output shaft extended axially
toward the support member and being connected to an external power
supply to rotate the output shaft; a drum member of a tubular
shape, open at one axial end and closed at the other axial end
thereof, the drum member being rotatably supported on outer
peripheral side of the support member at one axial end through
bearings; a reduction gear mechanism immersed in a lubricant oil
within the drum member, the reduction gear mechanism having a
single or multiple reduction stages to rotate the drum member at a
reduced speed; a coupling shaft extended axially in and through the
support member, the coupling shaft having one axial end connected
to the output shaft of the electric motor and the other axial end
rotatably supported in the lid portion of the support member and
coupled with the reduction gear mechanism; a negative type dry
electromagnetic brake accommodated in the support member to apply
the brakes to the coupling shaft when the electric motor is at rest
and take the brakes off to the coupling shaft when the electric
motor is in rotation; a first seal member forming a liquid tight
seal between the support member and an opening at one axial end of
the drum member; and a second seal member forming a liquid tight
seal between the lid portion of the support member and the coupling
shaft.
[0012] With the arrangements just described, an interstice between
the support member and an opening at one axial end of the drum
member is sealed up liquid tight by the first seal member, while an
interstice between the lid portion of the support member and the
coupling shaft is sealed up liquid tight by the second seal member,
shielding the negative type dry electromagnetic brake within the
support member from the lubricant oil in the drum member. Thus, by
the use of a dry electromagnetic brake, brakes can be applied to
the coupling shaft when the electric motor is at rest and take the
brakes off the coupling shaft when the electric motor is in
rotation.
[0013] Besides, the dry electromagnetic brake, shielded from the
lubricant oil, is accommodated in a compact form within the support
member which the electric motor and the reduction gear mechanism
are provided, making it possible to compactify the entirety of the
drum rotating apparatus incorporating the dry electromagnetic
brake.
[0014] (2) According to the present invention, a couple of the dry
electromagnetic brakes are provided in spaced positions in the
axial direction of the coupling shaft.
[0015] By a couple of the dry electromagnetic brakes which are
located within the support member, in spaced positions in the axial
direction of the coupling shaft, a large braking force can be
applied to the coupling shaft, holding the drum member standstill
when the electric motor is at rest. In this case, a free heat
releasing space can be formed between the two dry electromagnetic
brakes. Therefore, heat which is generated as a result of
excitation of the dry electromagnetic brakes can be efficiently
released into the heat releasing space between the two brakes. This
contributes to enhance durability of the dry electromagnetic brakes
and reliability of the drum rotating apparatus as well.
[0016] (3) According to the present invention, a couple of the dry
electromagnetic brakes are adapted to be assembled into the support
member commonly in the same direction toward the lid portion
through and from the side of an opening at one axial end of the
support member.
[0017] With the arrangements just described, the two dry
electromagnetic brakes can be assembled into the support member in
the same direction from and through an opening at one axial end of
the support member. This permits to assemble the dry
electromagnetic brakes into the support member in an efficient
manner.
[0018] (4) According to the present invention, the coupling shaft
is composed of a coupling having one axial end connected to the
output shaft of the electric motor and provided with a spline on
the outer periphery thereof, and an input shaft having one axial
end connected to the coupling and the other axial end connected to
the reduction gear mechanism; the dry electromagnetic brake being
comprised of a rotatable disc meshed with the spline of the
coupling for rotation therewith, an non-rotatable disc adapted to
be brought into and out of frictional engagement with the rotatable
disc by a displacement in an axial direction of the coupling, and
an electromagnetic coil excited by a power supply from outside to
disengage the non-rotatable disc from the rotatable disc.
[0019] In this manner, the coupling shaft which couples the output
shaft of the electric motor with the reduction gear mechanism is
constituted by a coupling and an input shaft. Therefore, for
example, after connecting the input shaft with the reduction gear
mechanism, the input shaft can be easily connected with the output
shaft of the electric motor by the coupling. Thus, the output shaft
of the electric motor can be coupled with the reduction gear
mechanism in an efficient manner.
[0020] (5) On the other hand, according to the present invention,
the drum rotating apparatus further comprising a connector
accommodation room provided upward of the dry electromagnetic brake
within the support member fixed on the basis, and a connector
mounted in the connector accommodation room to connect external
wiring to internal wiring leading to the dry electromagnetic
brake.
[0021] With the arrangements just described, even if rain water
should get into the support member through an interstice between
the support member and the electric motor, the connector can be
kept out of contact with rain water to guarantee higher reliability
of the electromagnetic brake.
[0022] (6) Further, according to the present invention, the basis
constitutes a truck frame of a crawler type lower structure of the
construction machine, the drum member is provided with a sprocket
fixedly on the outer periphery thereof for meshing engagement with
a crawler belt, and both of the electric motor and the reduction
gear mechanism are located within a width of the crawler belt in
transverse direction.
[0023] In case the drum rotating apparatus is applied to a vehicle
drive unit of a crawler type vehicle, for example, both of the
electric motor and the reduction gear mechanism can be located
within the width of a crawler belt, without being projected on the
outer side. Therefore, when the crawler type vehicle is traveling
on a rough terrain, the electric motor and the reduction gear
mechanism can be protected from rocks or other obstacles to
guarantee higher reliability of the vehicle drive unit.
BRIEF DESCRIPTION OF THE DRAWINGS
[0024] In the accompanying drawings:
[0025] FIG. 1 is a front elevation of a hydraulic excavator with a
vehicle drive unit incorporating a drum rotating apparatus
according to a first embodiment of the present invention;
[0026] FIG. 2 is an outer view of a truck frame and a vehicle drive
unit of the hydraulic excavator;
[0027] FIG. 3 is a sectional view of the vehicle drive unit shown
in FIG. 2;
[0028] FIG. 4 is an enlarged sectional view showing essential parts
such as a support member, an electric motor, a planetary reduction
gear mechanism and dry type electromagnetic brakes;
[0029] FIG. 5 is a sectional view of the dry type electromagnetic
brakes in a position for applying the brakes to an output
shaft;
[0030] FIG. 6 is a sectional view of the dry type electromagnetic
brakes in a position for taking the brakes off the output
shaft;
[0031] FIG. 7 is an enlarged sectional view similar to FIG. 4 but
showing a vehicle drive unit incorporating a drum rotating
apparatus according to a second embodiment of the present
invention; and
[0032] FIG. 8 is a sectional view similar to FIG. 5 but showing
essential parts of a third embodiment of the present invention.
BEST MODE FOR CARRYING OUT THE INVENTION
[0033] Hereafter, with reference to FIGS. 1 through 8, the drum
rotating apparatus of the construction machine according to the
present invention is described more particularly by way of its
preferred embodiments applied by way of example to a hydraulic
excavator with electric-powered vehicle drive units.
[0034] Referring to FIGS. 1 through 6, there is shown a first
embodiment of the present invention. In these figures, indicated at
1 is an electric-motorized hydraulic excavator. This
electric-motorized hydraulic excavator 1 is largely constituted by
an automotive lower structure 2 and an upper revolving structure 7
which is rotatably mounted on the lower structure 2 which will be
described hereinafter.
[0035] In this instance, the lower structure 2 is provided with a
truck frame 3 which is composed of a center frame 3A and right and
left side frames 3B. The truck frame 3 of this embodiment
constitutes a basis of the hydraulic excavator 1. An endless
crawler belt 6 is wrapped around a sprocket 4 and an idler 5 which
are provided at rear and front ends of each side frame 3B,
respectively.
[0036] Further, as shown in FIGS. 1 and 3, brackets 3C are
projected from the rear end of the side frame 3B for mounting a
support member 12 which will be described hereinafter. For covering
an electric motor 14 which will be described later on, a motor
cover 3D is fitted on the outer periphery of the brackets 3C.
[0037] Indicated at 7 is an upper revolving structure which is
mounted on the lower structure 2. The upper revolving structure 7
is largely constituted by a housing 8 and a cab 9. In this
instance, the housing 8 is largely constituted by a swing frame 8A
which is rotatably mounted on the truck frame 3, and a housing
cover 8B which is provided on the swing frame 8A to accommodate a
battery, an electric motor, a hydraulic pump, an operating oil tank
and so forth (none of which is shown in the drawings). The cab 9 is
built on a left front portion of the swing frame 8A, defining an
operating room thereon.
[0038] Denoted at 10 is a working mechanism, i.e., a lifting boom
mechanism, which is supported on a front portion of the upper
revolving structure 7. The front working mechanism 10 is
constituted by a boom 10A which is pivotally supported on the swing
frame 8A at its a base end through a pin, an arm 10B which is
pivotally connected to a fore distal end of the boom 10A through a
pin, a bucket 10C which is pivotally supported on a fore distal end
of the arm 10B through a pin, a boom cylinder 10D, an arm cylinder
10E and a bucket cylinder 10F.
[0039] At the time of an excavating groundwork, for example,
operating pressure oil is supplied to the respective cylinders 10D,
10E and 10F of the working mechanism 10 from a hydraulic pump (not
shown) which is accommodated in the housing cover 8B.
[0040] Shown at 11 is a vehicle drive unit of the lower structure
2, a typical example of application of the drum rotating apparatus
according to the invention. The vehicle drive unit 11 is provided
on each one of the left and right side frames 3B of the truck frame
3. As shown in FIGS. 3 and 4, each vehicle drive unit 11 is
constituted by a support member 12, an electric motor 14, a drum
member 15, a planetary reduction gear mechanism 21 and dry
electromagnetic brake or brakes 30.
[0041] Indicated at 12 is a support member which is fixed on each
side frame 3B of the truck frame 3, that is, a basis of the
vehicular base carrier. As shown in FIGS. 3 to 5, the support
member 12 is formed in the shape of a stepped and lidded tube which
is extended in the axial direction (in a rightward or leftward
direction). In this instance, the support member 12 is provided
with an axially extending tubular body portion 12A with an opening
12B at one axial end. An annular flange portion 12C is provided
around the opening 12B. As shown in FIGS. 3 and 4, the annular
flange portion 12C of the support member 12 is fixed to the
brackets 3C at the rear end of the side frame 3B by means of bolts
13. On the other hand, the opposite axial end of the tubular body
portion 12A is closed with a lid portion 12D which is centrally
provided with an axial bore 12E to receive an input shaft 28 (see
FIG. 5), which will be described hereinafter.
[0042] Further, provided on the inner peripheral side of the
tubular body portion 12A is a brake accommodation room 12F to
accommodate dry electromagnetic brakes 30 which will be described
later on. Further, for accommodation of a connector 41 which will
be described hereinafter, a connector accommodation room 12G is
provided upward of the dry electromagnetic brakes 30 within the
support member 12 which is attached to the truck frame 3. At the
other axial end, a spline 12H is formed on the outer periphery of
the tubular body portion 12A for meshing engagement with a carrier
25C of a planetary reduction gear mechanism 21 which will be
described hereinafter.
[0043] Indicated at 14 is a vehicle driving electric motor which is
mounted on the side of the opening 12B at one axial end of the
support member 12. In this instance, as shown in FIG. 3, the
electric motor 14 is an AC motor composed of an output shaft 14B
which is rotatably supported within a motor casing 14A and axially
extended within the support member 12, a rotor 14C which is
provided integrally around the outer periphery of the output shaft
14B, and a stator 14D which is located on the outer peripheral side
of the rotor 14C.
[0044] To rotate the output shaft 14B, the electric motor 14
receives a power supply from a battery which is accommodated within
the housing cover 8B after conversion into alternate current by an
inverter or the like (both the battery and inverter are not shown
in the drawings). A terminal box 14E is mounted on the upper side
of the motor casing 14A, the electric motor 14 including the
terminal box 14E is enshrouded in a motor cover 3D of the bracket
3C.
[0045] Denoted at 15 is a drum member which is roratably provided
on the outer peripheral side of the support member 12. As shown in
FIGS. 3 and 4, this drum member 15 is formed generally in the shape
of a stepped and lidded tube as a whole. In this instance, the drum
member 15 is comprised of a large-diameter tubular body 16 with an
opening 16A at one axial end, a tubular ring gear 17 which is
attached to the other axial end of the tubular body 16 and formed
with an internal gear 17A on its inner periphery, and a lid member
18 in the form of a circular disk closing the other axial end of
the ring gear 17 liquid tight.
[0046] A plural number of bearings 19 are provided between the
opening 16A of the tubular body 16 and the outer periphery of the
tubular body portion 12A of the support member 12. Thus, the drum
member 15 is rotatably supported on and around the outer periphery
of the tubular body portion 12A of the support member 12 through
the bearings 19. Further, by the use of a plural number of bolts
20, a sprocket 4 is fixed to an annular flange 16B which is
provided around the opening 16A of the tubular body 16.
[0047] Indicated at 21 is a planetary reduction gear mechanism
which is accommodated in the drum member 15. This planetary
reduction gear mechanism 21 transmits the rotation of the output
shaft 14B of the electric motor 14 to the drum member 15 at a
reduced speed to rotate the drum member 15 at a reduced speed and
with a large torque. In this instance, as shown in FIG. 4, the
planetary reduction gear mechanism 21 is constituted by planetary
reduction gear mechanisms 23, 24 and 25 with three speed reduction
stages which will be described hereinafter and immersed in
lubricant oil 22 which is held in the drum member 15. Thus, the
planetary reduction gear mechanism 21 is constantly lubricated by
the lubricant oil 22 and can be put in smooth operation over a long
period of time.
[0048] Designated at 23 is a planetary reduction gear mechanism of
the first stage. This planetary reduction gear mechanism 23 is
constituted by a sun gear 23B formed integrally on a shaft portion
23A extending axially within the ring gear 17, a plural number of
planet gears 23C meshed with the sun gear 23B and the internal gear
17A of the ring gear 17 and put in a revolving movement around the
sun gear 23B while spinning on the respective axes, and a carrier
23D rotatably supporting each planet gear 23C through a pin or the
like.
[0049] Indicated at 24 is a planetary reduction gear mechanism of
the second stage. This planetary reduction gear mechanism 24 is
constituted by a sun gear 24A splined with the carrier 23D of the
first stage, a plural number of planet gears 24B meshed with the
sun gear 24A and the internal gear 17A of the ring gear 17 and put
in a revolving movement around the sun gear 24A while spinning on
the respective axes, and a carrier 24C rotatably supporting each
one of the planet gears 24B through a pin or the like.
[0050] Indicated at 25 is a planetary reduction gear mechanism of
the third stage which will be the final stage. This planetary
reduction gear mechanism 25 is constituted by a sun gear 25A
splined with the carrier 24C of the second stage, a plural number
of planet gears 25B meshed with the sun gear 25A and the internal
gear 17A of the ring gear 17, and a carrier 25C rotatably
supporting each one of the planet gears 25B through a pin or the
like. In this instance, the carrier 25C is meshed with a spline 12H
formed around the outer periphery of the support member 12 at the
other axial end and fixed relative to the support member 12 in the
rotational direction.
[0051] Thus, the planetary reduction gear mechanism 25 of the third
stage is arranged to transmit to the drum member 15 only the
rotations of the planet gears 25B. In this manner, the speed of
rotation of the output shaft 14B of the electric motor 14 is
reduced by the planetary reduction gear mechanisms 23, 24 and 25 of
the respective stages of the planetary reduction gear mechanism 21,
and rotation of a reduced speed is transmitted to the ring gear 17
of the drum member 15. In this instance, the drum member 15 is
constituted to rotate with a large torque.
[0052] Indicated at 26 is a coupling shaft which is provided within
the support member 12 and extends in a longitudinal direction and
couples the output shaft 14B of the electric motor 14 with the
planetary reduction gear mechanism 21. In this instance, as shown
in FIGS. 4 and 5, the coupling shaft 26 is constituted by a
coupling 27 and an input shaft 28, which will be described later
on.
[0053] Denoted at 27 is a tubular coupling, one axial end of which
is connected to the output shaft 14B of the electric motor 14. A
male spline 27A is provided on the outer periphery of the coupling
27. At one axial end, the output shaft 14B of the electric motor 14
is splined with the inner periphery of the coupling 27, while the
male spline 27A of the coupling 27 is meshed with a rotating disk
36 of each dry electromagnetic brakes 30, which will be described
hereinafter.
[0054] Denoted at 28 is an input shaft which has one axial end
splined with the inner periphery of the coupling 27. The other end
of this input shaft 28 is received in an axial bore 12E which is
formed in the lid portion 12D of the support member 12. In this
instance, a plural number of bearings 29 are provided between the
input shaft 28 and the axial bore 12E of the support member 12, so
that the input shaft 28 is rotatably supported on the lid portion
12D of the support member 12 through the respective bearings 29.
Splined with the other axial end of the input shaft 28 is a shaft
portion 23A which is formed integrally with the sun gear 23B of the
planetary reduction gear mechanism 23 of the first stage.
[0055] Indicated at 30 are a couple of dry electromagnetic brakes
which are provided in spaced portions in the axial direction of the
support member 12. Each of these dry electromagnetic brakes 30
functions as a parking brake (negative brake) of the hydraulic
excavator 1. Namely, each of the dry electromagnetic brakes 30
apply the brakes to the output shaft 14B when the electric motor 14
is at a rest and take off the brakes to the output shaft 14B when
the electric motor 14 is in operation.
[0056] In this instance, as shown in FIGS. 5 and 6, each dry
electromagnetic brakes 30 are mounted within a brake accommodation
room 12F which is provided in the support member 12 around the
outer periphery of the coupling 27, and constituted by a yoke
member 31, a fixed plate 33, a rotatable disc 36, a non-rotatable
disc 37 and an electromagnetic coil 39, which will be described
hereinafter.
[0057] Indicated at 31 is a yoke member serving as a base of the
dry electromagnetic brake 30. This yoke member 31 is formed, for
example, by the use of a magnetic material and in the shape of a
thick disc having an axial bore 31A at the center. In that case,
each one of the yoke members 31 of the respective dry
electromagnetic brakes 30 is assembled into the brake accommodation
room 12F in the same direction toward the lid portion 12D through
and from the side of the opening 12B of the support member 12, and
fixed in position by the use of a plural number of bolts 32 (only
one bolt is shown in the drawing). The coupling 27 of the coupling
shaft 26 is placed in the axial bore 31A in the yoke member 31 in a
small gap relation with the latter.
[0058] Further, the yoke member 31 is provided with an annular
recess 31B in concentric relation with the axial bore 31A, and an
electromagnetic coil 39 which will be described later on is
accommodated in the recess 31B. Further, the yoke member 31 is
provided with a plural number of bottomed holes 31C which is
extended in axial direction (only one of which is shown in the
drawing) to accommodate coil springs 38, which will be described
hereinafter.
[0059] Indicated at 33 is a fixed plate in the form of a circular
hollow disc, which is provided fixedly on the yoke member 31. The
coupling 27 is passed through the fixed plate 33 on the inner
peripheral side of the latter. The fixed plate 33 is securely fixed
to the yoke member 31 by the use of a plural number of bolts 34 and
cylindrical guides 35 (only one of which is shown in the drawing)
at a number of radially spaced positions. In this case, the fixed
plate 33 is fixed to the yoke member 31 by the bolts 34 having fore
end portions threaded into the yoke member 31 through the guides
35.
[0060] Indicated at 36 is a rotatable disc which is meshed with the
male spline 27A of the coupling 27 and located between the yoke
member 31 and the fixed plate 33. In this instance, the rotatable
disc 36 is in the form of a hollow circular disc and provided with
a female spline 36A on the inner peripheral side. The rotatable
disk 36 rotates with the coupling 27 by meshing the female spring
36A with the male spline 27A of the coupling 27.
[0061] Designated at 37 is a non-rotatable disc which is mounted
displaceably in the axial direction of the coupling 27 between the
yoke member 31 and the fixed plate 33. This non-rotatable disc 37
is formed in the shape of a hollow circular disc, and the coupling
27 is passed through the inner peripheral side of the non-rotatable
disc 37. The non-rotatable disc 37 functions to grip the rotatable
disc 36 in cooperation with the fixed plate 33. In this instance,
the non-rotatable disc 37 is locked in a non-rotatable state
relative to the coupling 27 by the guides 35 which are passed
through outer peripheral portions of the non-rotatable disc 37, but
allowed to move in the axial direction of the coupling 27 along the
guides 35.
[0062] Indicated at 38 are coil springs which are set in a plural
number of bottomed holes 31C (only one of which is shown in the
drawings) which are bored into the yoke member 31, thereby to
constantly press the non-rotatable disc 37 toward the fixed plate
33. When power supply to the electromagnetic coil 39 is cut off,
the non-rotatable disc 37 is pressed against and held in frictional
engagement with the rotatable disc 36 by the forces of the coil
springs 38 as shown in FIG. 5 to restrict rotation of the rotatable
disc 36. As a consequence, the brakes are applied to the output
shaft 14B of the electric motor 14 which is coupled with the
rotatable disc 36 through the coupling 27.
[0063] Indicated at 39 is an electromagnetic coil which is
accommodated in the recess 31B of the yoke member 31. This
electromagnetic coil 39 is supplied with power, for example,
simultaneously with the electric motor 14, and thereby excited to
magnetically attract the non-rotatable disc 37. As a result, as
shown in FIG. 6, the non-rotatable disc 37 is moved away from the
rotatable disc 36 against the forces of the coil springs 38,
bringing the non-rotatable disc 37 out of frictional engagement
with the rotatable disc 36 to put the brakes off the output shaft
14B of the electric motor 14.
[0064] Indicated at 40 is a space which is provided within the
brake accommodation room 12F of the support member 12. This space
40 is provided between the two dry electromagnetic brakes 30 which
are located in axially spaced positions. Heat which is generated by
excitation of the electromagnetic coils 39 of the each dry
electromagnetic brakes 30 is released to this space 40.
[0065] Further, the two dry electromagnetic brakes 30 are
accommodated in the support member 12 between the electric motor 14
and the planetary reduction gear mechanism 21. Thus, as shown in
FIG. 3, both of the electric motor 14 and the planetary reduction
gear mechanism 21 can be located within the width S of the crawler
belt 6 (belt width) in the transverse direction.
[0066] Indicated at 41 is a connector which is mounted in a
connector accommodation room 12G within the support member 12. This
connector 41 is composed of a connector member 41A on the side of
the brakes and a connector member 41B on the side of the power
supply. In this instance, the connector member 41A on the side of
the brakes is provided at the distal end of an internal wiring 42
which is connected to the electromagnetic coil 39, while the
connector member 41B on the side of the power supply is provided at
the distal end of an external wiring 43 which is connected to a
power source (not shown). By connecting the connector member 41B on
the side of the power supply with the connector member 41A on the
side of the brake, the electromagnetic coils 39 of the dry
electromagnetic brakes 30 are connected to the power source.
[0067] In this instance, the connector accommodation room 12G of
the support member 12 is provided upward of the dry electromagnetic
brakes 30, so that the connector 41 which is mounted in the
connector accommodation room 12G can be kept out of contact with
rain water even in the event rain water gets into the support
member 12 through an interstice between the electric motor 14 and
the support member 12.
[0068] Indicated at 44 is a floating seal adopted as a first liquid
tight seal member to provide a liquid tight seal between the
opening 16A of the tubular body 16 of the drum member 15 and the
support member 12. As shown in FIG. 4 and so forth, the floating
seal 44 is of an annular shape and placed fully around the opening
16A and the support member 12. The floating seal 44 forms as a
liquid tight seal between the fixed support member 12 and rotating
drum member 15, sealing up the lubricant oil 22 of the bearings 19
and the planetary reduction gear mechanism 21 within the drum
member 15.
[0069] Indicated at 45 is a seal ring of U-shape in section adopted
as a second seal member for providing a liquid tight seal between
the lid portion 12D of the support member 12 and the coupling shaft
26. This seal ring 45 is located between the axial bore 12E in the
lid portion 12D and the input shaft 28 of the coupling shaft 26.
The seal ring 45 seal between the axial bore 12E and the input
shaft 28, preventing the lubricant oil 22 in the drum member 15
from flowing into the brake accommodation room 12F within the
support member 12.
[0070] Being arranged as described above, the vehicle drive unit 11
of the hydraulic excavator 1 according to the present embodiment
gives the following performances in operation.
[0071] When the electric motor 14 of the vehicle drive unit 11 is
at rest with no power supply thereto, the electromagnetic coil 39
of each dry electromagnetic brakes 30 is also in a de-energized
state with no power supply. At this time, as shown in FIG. 5, the
non-rotatable disc 37 is pressed toward and urged into frictional
engagement with the rotatable disc 36 by the coil springs 38, so
that the rotatable disc 36 is gripped between the fixed plate 33
and the non-rotatable disc 37. As a result, the rotatable disc 36
is restricted of rotation, applying the brakes to the output shaft
14B of the electric motor 14 which is connected to the rotatable
disc 36 through the coupling 27, to function as a parking brake (a
negative brake) of the hydraulic excavator 1.
[0072] On the other hand, when power is supplied to the electric
motor 14 of the vehicle drive unit 11 to put the hydraulic
excavator 1 in travel, power is also supplied to the
electromagnetic coil 39 of each dry electromagnetic brakes 30
through the connector 41. At this time, the electromagnetic coils
39 are energized, so that the non-rotatable disc 37 is magnetically
attracted toward the electromagnetic coils 39 against spring
actions of the coil springs 38, as shown in FIG. 6. As a result,
the non-rotatable disc 37 is disengaged from the rotatable disc 36
to take the brakes off the output shaft 14B of the electric motor
14.
[0073] Thus, rotation of the output shaft 14B of the electric motor
14 is transmitted to the drum member 15 after the three-stage speed
reductions by the planetary reduction gear mechanism 21. The
sprocket 4 which fixed on the tubular body 16 of the drum member 15
is put in rotation with a large torque together with the drum
member 15. The crawler belt 6 which is meshed with the sprocket 4
is driven to turn around the sprocket 4 and idler 5, putting the
hydraulic excavator 1 in travel.
[0074] Thus, according to the present embodiment, by the provision
of the floating seal 44 which forms a fluid tight seal between the
support member 12 and the opening 16A of the drum member 15
(tubular body 16), and the seal ring 45 which forms a liquid tight
seal between the axial bore 12E in the lid portion 12D of the
support member 12 and the coupling shaft 26 (the input shaft 28),
the two dry electromagnetic brakes 30 can be accommodated within
the support member 12 in a shielded state from the inflammable
lubricant oil 22 held in the drum member 15. Thus, the dry
electromagnetic brakes 30 can be used for applying the brakes to
the coupling shaft 26 when the electric motor 14 is at rest and
take the brakes off the coupling shaft 26 when the electric motor
14 is in rotation.
[0075] Further, each one of the dry electromagnetic brakes 30 can
be accommodated in a compact form within the support member 12
which is assembled with the electric motor 14 and the planetary
reduction gear mechanism 21, permitting to downsize the vehicle
drive unit 11 incorporating the dry electromagnetic brakes 30.
[0076] Accordingly, as shown in FIG. 3, the electric motor 14 and
the planetary reduction gear mechanism 21 can be located within the
width S of the crawler belt 6 (belt width) in the transverse
direction, preventing the electric motor 14 or the planetary
reduction gear mechanism 21 from projecting on the outer side of
the crawler belt 6. Therefore, when the hydraulic excavator 1 is
traveling on a rough unlevel terrain, for example, the electric
motor 14 and planetary reduction gear mechanism 21 can be protected
from rocks or other obstacles to ensure higher reliability of the
vehicle drive unit 11.
[0077] Further, the use of the electric motor 14 in the vehicle
drive unit 11 obviates an engine which has thus far been used in a
hydraulic motor type vehicle drive unit for driving a hydraulic
pump which supplies pressure to a hydraulic motor. That is to say,
obviation of an engine means suppression of exhaust gases and
noises which are issued from an engine when the hydraulic excavator
1 is in travel, and thus can contribute to improvements of working
environment to a significant degree.
[0078] Further, according to the present embodiment, a couple of
dry electromagnetic brakes 30 are mounted in axially spaced
positions within a brake accommodation room 12F within the support
member 12. Therefore, when the electric motor 14 is at rest, a
large braking force can be applied to the output shaft 14B by the
two dry electromagnetic brakes 30, permitting to stop (park) the
hydraulic excavator 1 securely.
[0079] Besides, a free space 40 is provided between the two dry
electromagnetic brakes 30, so that heat which is generated as a
result of excitation of the electromagnetic coils 39 of the two dry
electromagnetic brakes 30 can be released into the space 40
efficiently. This contributes to enhance the durability of the dry
electromagnetic brakes 30 and the reliability of the vehicle drive
unit 11.
[0080] Further, the two dry electromagnetic brakes 30 are each
fixed in the support member 12. That is to say, the two dry
electromagnetic brakes 30 can be assembled into the support member
12 prior to assembling the electric motor 14 with the support
member 12. This permits to perform an assembling work in an
efficient manner.
[0081] In this instance, each one of the two dry electromagnetic
brakes 30 is assembled into the brake accommodation room 12F within
the support member 12 in the same direction toward the lid portion
12D through the opening 12B and fixed in position by the use of a
plural number of bolts 32. That is to say, the two dry
electromagnetic brakes 30 can be assembled commonly from the same
direction relative to the support member 12 and in an efficient
manner.
[0082] Furthermore, the coupling shaft 26 which couples the output
shaft 14B of the electric motor 14 with the planetary reduction
gear mechanism 21 is constituted by the coupling 27 and the input
shaft 28. Therefore, for example, after coupling the input shaft 28
with the planetary reduction gear mechanism 21, the output shaft
14B of the electric motor 14 can be coupled with the input shaft 28
easily by the coupling 27 in an efficient manner.
[0083] Moreover, the connector accommodation room 12G is provided
within the support member 12, at a position upward of the dry
electromagnetic brakes 30, to accommodate the connector 41
connecting the power supply external wring 43 with the internal
wiring 42 which is connected to the electromagnetic coils 39 of the
dry electromagnetic brakes 30. Therefore, even if rain water flow
into the support member 12 through an interstice between the
support member 12 and the electric motor 14, the connector 41 can
be kept out of contact with rain water, to enhance operational
reliability of the dry electromagnetic brakes 30.
[0084] Now, turning to FIG. 7, there is shown a second embodiment
of the present invention. This embodiment has a feature in that one
of the two electromagnetic brakes which are provided internally of
the support member is fixed to the support member, while the other
one of the electromagnetic brakes is fixed to the electric motor.
In the following description of the second embodiment, those
component parts which are identical with the counterparts in the
foregoing first embodiment are simply designated by the same
reference numerals and characters to avoid repetitions of same
explanations.
[0085] In the drawing, indicated at 51 is a vehicle drive unit
incorporating a drum rotating apparatus of the present embodiment.
Substantially in the same way as the vehicle drive unit 11 in the
above-described first embodiment, the vehicle drive unit 51 is
constituted by a support member 12, an electric motor 14, a drum
member 15, a planetary reduction gear mechanism 21 and a couple of
dry electromagnetic brakes 30 and 52.
[0086] However, this embodiment differs from the first embodiment
in that one dry electromagnetic brake 30 is fixed to the support
member 12, while the other dry electromagnetic brake 52 is fixed to
a motor casing 14A of the electric motor 14.
[0087] Indicated at 52 is a dry electromagnetic brake which is
provided within a brake accommodation room 12F of the support
member 12 together with another dry electromagnetic brake 30.
Similarly to the dry electromagnetic brake 30, the dry
electromagnetic brake 52 is constituted by a yoke member 31, a
fixed plate 33, guides 35, a rotatable disc 36, a non-rotatable
disc 37, coil springs 38 and an electromagnetic coil 39.
[0088] The dry electromagnetic brake 52 is fixedly mounted within
the support member 12 by the use of a plural number of bolts 53
(only one bolt is shown in the drawing) which are passed through
the fixed plate 33, guides 35 and the yoke member 31 and threaded
into the motor casing 14A of the electric motor 14.
[0089] Being arranged as described above, the vehicle drive unit 51
of the present embodiment practically has no difference in
particular from the above-described performances of the foregoing
first embodiment in performance.
[0090] Nevertheless, according to the present embodiment, of the
two dry electromagnetic brakes 30 and 52 which are located within
the support member 12, one dry electromagnetic brake 30 is fixed to
the support member 12 while the other dry electromagnetic brake 52
is fixed to the motor casing 14A of the electric motor 14,
providing a broad free space 54 between the two dry electromagnetic
brakes 30 and 52 to accelerate release of heat from the two dry
electromagnetic brakes 30 and 52 all the more.
[0091] Now, turning to FIG. 8, there is shown a third embodiment of
the present invention. This third embodiment has a feature in that
a coupling shaft which couples an output shaft of an electric motor
with a reducer is constituted by one and single member. In the
following description of the third embodiment, those component
parts which are identical with the counterparts in the foregoing
first embodiment are simply designated by the same reference
numerals and characters to avoid repetitions of same
explanations.
[0092] In the drawing, designated at 61 is a coupling shaft which
is axially extended in and through a support member 12. This
coupling shaft 61 is adapted to couple an output shaft 14B of an
electric motor 14 with a planetary reduction gear mechanism 21. In
this instance, the coupling shaft 61 is constituted by a single
shaft member which has one axial end thereof formed as a coupling
portion 61A, and the other axial end as an input shaft portion
61B.
[0093] The coupling portion 61A is connected with the output shaft
14B of the electric motor 14, and provided with a spline 61C on its
circumferential surface for meshing engagement with rotatable discs
36 of the dry electromagnetic brakes 30. The input shaft portion
61B is splined with a shaft portion 23A on the side of a planetary
gear mechanism of the first stage, and rotatably supported in a lid
portion 12D of the support member 12 through bearings 29.
[0094] Except for the adoption of the coupling shaft 61 which is
provided with the coupling portion 61A and the input shaft portion
61B integrally at opposite axial ends as described above, this
embodiment is identical with the foregoing first embodiment in
other respects.
[0095] In each one of the foregoing embodiments, the present
invention has been described by way of an application using a
planetary reduction gear mechanism with three reduction stages.
However, needless to say, the present invention is not limited to
such a planetary reduction gear mechanism, and can be similarly
applied to a single stage planetary reduction gear mechanism or to
a planetary reduction gear mechanism with two or more than four
reduction stages.
[0096] Further, in each one of the foregoing embodiments as
described above, the vehicle drive unit 11 of the hydraulic
excavator 1 has been shown as an example of application of the drum
rotating apparatus of the invention. However, the present invention
is similarly applicable to other drum rotating apparatus, for
example, to rope winches which are mounted on hydraulic cranes. In
that case, the drum member is in the form of a take-up drum which
is adapted to take up a rope on and around its outer periphery.
* * * * *