Title: Two-speed gearbox with integrated differential
Abstract: A gearbox assembly includes a housing which contains a differential gear set and a two-speed reduction gear set. A spider drives differential pinion gears nested between outer pinion gears. A first and a second clutch that can be engaged "on the fly" achieve the two-speed functionally of the gearbox assembly. Another gearbox assembly includes an on-demand locking differential with a differential clutch located between differential axle side gears to selectively lock the differential axle side gears together and thereby lock the axle shafts.
Patent Number: 6,843,750 Issued on 01/18/2005 to Bennett
| Inventors:
|
Bennett; John L. (Fraser, MI)
|
| Assignee:
|
ArvinMeritor Technology, LLC (Troy, MI)
|
| Appl. No.:
|
630417 |
| Filed:
|
July 30, 2003 |
| Current U.S. Class: |
475/273; 475/310 |
| Intern'l Class: |
F16H 003/44 |
| Field of Search: |
475/273,310,309
|
References Cited [Referenced By]
U.S. Patent Documents
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|
| 2997898 | Aug., 1961 | Ellis | 475/139.
|
| 3511112 | May., 1970 | Ellis et al. | 475/145.
|
| 4588040 | May., 1986 | Albright, Jr. et al.
| |
| 5100368 | Mar., 1992 | Chien.
| |
| 5201691 | Apr., 1993 | Doyle.
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| 5558589 | Sep., 1996 | Schmidt.
| |
| 5827148 | Oct., 1998 | Seto et al.
| |
| 5951424 | Sep., 1999 | Briceland.
| |
| 6041877 | Mar., 2000 | Yamada et al.
| |
| 6053833 | Apr., 2000 | Masaki.
| |
| 6083138 | Jul., 2000 | Aoyama et al.
| |
| 6083139 | Jul., 2000 | Deguchi et al.
| |
| 6090005 | Jul., 2000 | Schmidt et al.
| |
| 6098733 | Aug., 2000 | Ibaraki et al.
| |
| 6110066 | Aug., 2000 | Nedungadi et al.
| |
| 6170587 | Jan., 2001 | Bullock.
| |
| 6358176 | Mar., 2002 | Nauheimer et al.
| |
| 6371878 | Apr., 2002 | Bowen.
| |
| 6378638 | Apr., 2002 | Mizon et al.
| |
| 6398685 | Jun., 2002 | Wachauer et al.
| |
| 6401850 | Jun., 2002 | Bowen.
| |
| 6481519 | Nov., 2002 | Bowen.
| |
| 6499549 | Dec., 2002 | Mizon et al.
| |
Other References
Hybrid Diesel-Electric Engines, http://www.g2mil.com/hybrid.htm.
|
Primary Examiner: Wright; Dirk
Attorney, Agent or Firm: Carlson, Gaskey & Olds
Claims
What is claimed is:
1. A two-speed gearbox assembly comprising:
a housing;
a case rotationally mounted within said housing;
a differential spider mounted to said case, said differential spider
comprising a plurality of legs which mount a plurality of inner
differential pinion gears and a plurality of outer pinion gears;
a first clutch mounted between said housing and said case to selectively
lock an input side gear to said case to provide a first reduction ratio;
and
a second clutch mounted to said housing to selectively lock an opposite
side gear to said housing to provide a second reduction ratio.
2. The two-speed gearbox assembly as recited in claim 1, further
comprising:
a differential spider mounted to said case, said differential spider
comprising a plurality of legs which mount a plurality of inner
differential pinion gears and a plurality of outer pinion gears;
a first axle shaft engaged with said inner differential pinion gears, said
first axle shaft defined along an axis of rotation; and
a second axle shaft engaged with each of said differential pinion gears,
said second axle shaft defined along said axis of rotation.
3. The two-speed gearbox assembly as recited in claim 2, further
comprising:
a first differential axle side gear mounted to said first axle shaft;
a second differential axle side gear mounted to said second axle shaft;
a locking differential clutch mounted between said first and second
differential axle side gears to selectively lock said first and second
differential axle side gears together.
4. The two-speed gearbox assembly as recited in claim 3, further
comprising:
a split differential spider comprising a plurality of legs in which
pressurized fluid is communicated along the length of each of said
plurality of legs.
5. The two-speed gearbox assembly as recited in claim 3, further
comprising:
a split differential spider comprising a plurality of legs;
a plurality of sealed pistons located within said split differential spider
such that in response to a pressurized fluid communicated along the length
of each of said plurality of legs said plurality of sealed pistons actuate
said locking differential clutch to selectively lock said first and second
differential axle side gears together.
6. The two-speed gearbox assembly as recited in claim 1, wherein:
said input side gear coaxially mounted about said axis of rotation and
engaged with said outer pinion gears; and
said opposite side gear coaxially mounted about said axis of rotation and
engaged with said outer pinion gears.
7. The two-speed gearbox assembly as recited in claim 1, further
comprising:
a biasing member which maintains said first clutch in an actuated
condition.
8. The two-speed gearbox assembly as recited in claim 1, further
comprising:
a biasing member which maintains said second clutch in an actuated
condition.
9. A two-speed gearbox assembly comprising:
a housing;
a case rotationally mounted within said housing;
a differential spider mounted to said case, said differential spider
comprising a plurality of legs which mount a plurality of inner
differential pinion gears and a plurality of outer pinion gears;
a first axle shaft engaged with said inner differential pinion gears, said
first axle shaft defined along an axis of rotation;
a second axle shaft engaged with each of said differential pinion gears,
said second axle shaft defined along said axis of rotation;
an input side gear coaxially mounted about said axis of rotation and
engaged with said outer pinion gears;
an opposite side gear coaxially mounted about said axis of rotation and
engaged with said outer pinion gears;
a first clutch mounted between said housing and said case to selectively
lock said input side gear to said case to provide a first reduction ratio;
and
a second clutch mounted to said housing to selectively lock said opposite
side gear to said housing to provide a second reduction ratio.
10. The two-speed gearbox assembly as recited in claim 9, further
comprising:
a biasing member which maintains said first clutch in an actuated
condition.
11. The two-speed gearbox assembly as recited in claim 9, further
comprising:
a biasing member which maintains said second clutch in an actuated
condition.
12. The two-speed gearbox assembly as recited in claim 9, wherein said
differential spider comprises a split differential spider comprising a
plurality of legs in which pressurized fluid is communicated along the
length of each of said plurality of legs.
13. The two-speed gearbox assembly as recited in claim 12, further
comprising:
a first differential axle side gear mounted to said first axle shaft;
a second differential axle side gear mounted to said second axle shaft; and
a locking differential clutch mounted within said split differential clutch
to selectively lock said first and second differential axle side gears
together.
14. The two-speed gearbox assembly as recited in claim 12, wherein said
differential spider comprises a split differential spider a split
differential spider comprising a plurality of legs; and
a plurality of sealed pistons located within said split differential spider
such that in response to a pressurized fluid communicated along the length
of each of said plurality of legs, said plurality of sealed pistons
actuate said locking differential clutch to selectively lock a first and a
second differential axle side gears together to lock said first axle shaft
to said second axle shaft.
15. The two-speed gearbox assembly as recited in claim 9, further
comprising:
an electric motor which drives said input side gear.
16. A method of selecting between a first and a second reduction ratio
comprising the steps of:
(1) selectively actuating a first clutch mounted between a housing and a
case rotationally mounted within the housing to selectively lock an input
side gear to the case to provide a first reduction ratio; and
(2) selectively actuating a second clutch mounted to the housing to
selectively lock an opposite side gear to the housing to provide a second
reduction ratio.
17. A method as recited in claim 16, wherein said step (1) further
comprising the step of:
selectively actuating a locking differential clutch mounted within a split
differential clutch to selectively lock a first and second differential
axle side gear together to selectively lock a first and a second axle
shaft.
18. A method as recited in claim 16, wherein said step (1) further
comprising the step of:
biasing the first clutch to an actuated condition.
19. A method as recited in claim 16, wherein said step (1) further
comprising the step of:
biasing the second clutch to an actuated condition.
Description
BACKGROUND OF THE INVENTION
The present invention relates to a two-speed gearbox, and more particularly
to a two-speed gearbox having a locking differential for a heavy hybrid
electric vehicle.
There is an increasing demand for the use of hybrid electric driven and
hybrid electric assisted vehicles. Hybrid electric vehicle typically
utilize motor driven axles which are often of a multi-axle configuration
in military and specialty vehicles systems.
The electric motors are typically sized to meet both torque and speed
requirements which may not be the most effective for the operational
requirements of such vehicles. Relatively large electric motors are often
utilized to meet the torque requirements which may result in an oversized
motor for most operational conditions. Moreover, the relatively large
electric motors may be difficult to package in a multi-axle configuration.
A lightweight and compact reduction gearbox which allows the usage of
relatively smaller electric motors is therefore desirable. Two speeds are
particularly desirable for military and specialty vehicles to provide high
torque in off road conditions and high speed for movement over roads.
Military and specialty vehicles systems also typically require the added
traction provided by a biasing or locking differential. A full time
biasing differential may be undesirable in such vehicle since a primary
motivation for transition to hybrid electric driven vehicles is improved
fuel economy which provides increased range and reduced logistic
footprint.
Accordingly, it is desirable to provide a lightweight and compact two-speed
reduction gearbox and on-demand biasing differential which may be utilized
with a relatively smaller electric motor for incorporation into a
multi-axle military and specialty vehicle system.
SUMMARY OF THE INVENTION
The gearbox assembly according to the present invention includes a housing
which contains a differential gear set and a two-speed reduction gear set.
A differential spider drives differential pinion gears which are nested
between outer pinion gears. A first and a second clutch that can be
engaged "on the fly" achieve the two-speed functionality of the gearbox
assembly. The first clutch is mounted between a case and the housing to
selectively lock an input side gear to the case. The second clutch is
mounted within the housing to selectively lock an opposite side gear to
the housing.
In operation, the input to the gearbox assembly is through the input side
gear. To provide a first reduction ratio a piston collapses the first
clutch to lock the input side gear to the case. The case is assembled
about a differential spider and therefore rotates the differential spider
at the same speed as the case and the input side gear to achieve a 1:1
ratio. Engaging the differential pinion gears are the differential axle
side gear which drive the axle shaft. Because the differential pinion
gears are free to rotate around the differential spider, the differential
axle side gear are free to rotate at different speeds creating a
differential effect.
To provide a second reduction ratio the second clutch locks the opposite
side gear to the housing. With the opposite side gear grounded, the first
and second outer pinion gear roll around the opposite side gear rotating
the differential spider at half the speed of the input side gear to
achieve the second reduction ratio.
Another gearbox assembly includes an on-demand locking differential. The
locking differential clutch is located between differential axle side
gears to selectively lock the differential axle side gears and thereby
lock the axle shafts together.
The present invention therefore provides a lightweight and compact
two-speed reduction gearbox and on-demand biasing differential which may
be utilized with a relatively smaller electric motor for incorporation
into a multi-axle military and specialty vehicle system.
BRIEF DESCRIPTION OF THE DRAWINGS
The various features and advantages of this invention will become apparent
to those skilled in the art from the following detailed description of the
currently preferred embodiment. The drawings that accompany the detailed
description can be briefly described as follows:
FIG. 1 is a general perspective view an exemplary multi-axle vehicle
embodiment for use with the present invention;
FIG. 2 is a block diagram of an axle assembly of the present invention;
FIG. 3 is a schematic sectional view of a two-speed gearbox;
FIG. 4 is a planar view of a differential spider for use in the gear box of
FIG. 3; and
FIG. 5 is a schematic sectional view of another two-speed gearbox with an
on-demand locking differential.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
FIG. 1 illustrates a schematic partial phantom view of a multi-axle vehicle
10 having a body 12 supported upon a frame 14. The frame 14 preferably
includes a pair of main longitudinal members 16. It should be understood
that although a particular vehicle arrangement is disclosed in the
illustrated embodiment, other vehicles will benefit from the present
invention.
A multiple of axle assemblies 20 each includes an axle 22 driven by one or
more electric motors 24. Each axle assembly 20 defines an axis of rotation
A substantially transverse the longitudinal members 16 to drive one or
more wheels 26. The electric motors 24 are driven by a prime mover 28
which is preferably a hybrid electric drive which powers each of the axle
assemblies 20 by powering the electric motors 24. It should be understood,
however, that other prime movers such as diesel engines, gas turbines
among others will also benefit from the present invention.
Referring to FIG. 2, the electric motors 24 drive a gearbox assembly 30
which drives the wheels 26 through a first axle shaft 32a and a second
axle shaft 32b located along axis D. Preferably, the electric motors 24
drive the gearbox assembly 30 through an input side gear 34 (illustrated
schematically) which is coaxial with axis D.
Each wheel 26 is preferably supported by an independent suspension
(illustrated schematically at 36). The independent suspensions 36 may be
mounted directly to the gearbox assembly 30. Each wheel 26 and supporting
suspension 36 moves independently relative to the electric motors 24,
gearbox assembly 30 which are mounted to the vehicle frame 14 (FIG. 1). It
should be understood that other suspension systems such as a rigid tubular
or box axle which contains the gearbox assembly will also benefit from the
present invention.
The gearbox assembly 30 is preferably a two-speed reduction gear set 38
that includes a differential gear set 40 substantially contained within
the two-speed reduction gear set 38. That is, differential gear set 40 is
nested within the two-speed reduction gear set 38. A relatively
lightweight and compact gearbox assembly 30 is thereby provided which will
benefit from an electric motor of reduced size.
Referring to FIG. 3, the gearbox assembly 30 is schematically illustrated.
The gearbox includes a housing 42 which contains the differential gear set
40 and the two-speed reduction gear set 38. The housing 42 receives the
first and second axle shaft 32a, 32b along axis D. The input side gear 34a
is coaxial with axis D and is driven by the electric motors 24 (FIG. 2).
A differential spider 44 is mounted to a case 46. The case 46 is contained
within the housing 42 and rotates about axis D upon bearings 47. The
spider 44 is mounted generally transverse to axis D. A multiple of outer
pinion gear 48a, 48b, 48c, 48d are mounted for rotation about the
differential spider 44 (FIG. 4). A multiple of inner differential pinion
gear 52a, 52b, 52c, 52d are mounted for rotation about the differential
spider 44 independent of the outer pinion gears 48a-48d. That is, the
inner differential pinion gears 52a-52d and the outer pinion gears 48a-48d
are mounted for independent rotation on the legs of the differential
spider 44. As generally known the spider includes multiple legs (FIG. 4),
each of which includes one outer pinion gear 48 and one inner differential
pinion gear 52 (FIG. 4) although only two legs are illustrated in the
sectional view of FIG. 3. Notably, the differential pinion gears 52a-52d
are nested between the outer pinion gears 48a-48d.
The input side gear 34a is engaged with the outer pinion gears 48a-48d. An
opposite side gear 34b opposite the input side gear 34a is likewise
engaged with the outer pinion gears 48a-48d. It should be understood that
although the input side gear 34a is coaxial with axle shaft 32a and the
opposite side gear 34 is coaxial with axle shaft 32b in the illustrated
embodiment, the opposite or other arrangements will also benefit from the
present invention.
A first differential axle side gear 56a is mounted to the first axle shaft
32a and a second differential axle side gear 56b is mounted to the second
axle shaft 32b. The first and second differential axle side gears 56a, 56b
engage the inner differential pinion gears 52a-52d.
A first and a second clutch 58a, 58b that can be engaged "on the fly"
achieve the two-speed functionality of the gearbox assembly 30. The first
clutch 58a is mounted between the case 46 and the housing 32 and is
actuated by a first piston 60a to selectively lock the input side gear 34a
to the case 46. The second clutch 58b is mounted within the housing 32 and
is actuated by a second piston 60b to selectively lock the opposite side
gear 34b to the housing 32. Alternatively, or additionally, the locking
effect can achieved by a dog clutch, sliding collar, amongst others. The
pistons 60a, 60b are actuated by a pressurized fluid and/or spring in
response to a controller 62 (illustrated schematically).
It should be further understood that various bearing and seal locations are
included within the gearbox. One of ordinary skill in the art, with the
benefit of this disclosure, will consider the various bearing and seal
locations to be an ordinary engineering problem such that intricate
details thereof need not be fully discussed herein.
In operation, the input to the gearbox assembly 30 is through the input
side gear 34a. To provide a first reduction ratio (1:1 ratio), the piston
60a is actuated by controller 32 and the piston 60b is not energized. The
piston 60a collapses the clutch pack 58a to lock the input side gear 34a
to the case 46. The case 46 is assembled about the differential spider 44
and therefore rotates the differential spider 44 at the same speed as the
case 46 and the input side gear 34a to achieve a 1:1 ratio. The
differential spider 44 drives the differential pinion gears 52a, 52b which
are nested between the first and second outer pinion gear 48a, 48b.
Engaging the differential pinion gears 52a, 52b are the differential axle
side gear 56a, 56b which drive the axle shaft 32a, 32b. Because the
differential pinion gears 52a, 52b are free to rotate around the
differential spider 44, the differential axle side gear 56a, 56b are free
to rotate at different speeds creating a differential effect.
To provide a second reduction ratio (2:1 shown, but other ratios are
achieved by providing an angled spider as generally understood), the
piston 60b is actuated by controller 32 and the piston 60a is not
energized. The piston 60b collapses the clutch pack 58b to lock the
opposite side gear 34b to the housing 42. With the opposite side gear 34b
grounded, the first and second outer pinion gear 48a, 48b roll around the
opposite side gear 34b rotating the differential spider 44 at half the
speed of the input side gear 34a and achieving the 2:1 reduction. The
differential spider 44 drives the differential pinion gears 52a, 52b which
rotate the differential axle side gears 56a, 56b and drive the axle shaft
32a, 32b.
Alternatively, the gearbox assembly 30 can be biased toward a single
reduction ratio such that that the selected reduction ratio is the usual
un-powered ratio provided by the gearbox assembly 30. That is, the gearbox
assembly 30 always operated in a single selected reduction ration unless
power is applied to overcome the bias and actuate the other reduction
ratio. A biasing member (illustrated schematically at 55) such as a spring
or the like biases one piston 60a, 60b. Actuation of the one piston 60a,
60b overcomes the biasing member 55 and actuation of the opposite piston
60b, 60a operates as described above to provide the second reduction
ratio. Such an arrangement is particularly beneficial when one reduction
will be know to be utilized more often than the other.
Referring to FIG. 5, another gearbox assembly 30' which includes an
on-demand locking differential is schematically illustrated. The gearbox
assembly 30 generally includes the components of gearbox assembly 30 with
a locking differential clutch 64 which is controlled by controller 62. The
locking differential clutch 64 is located between the differential axle
side gears 56a, 56b to selectively lock the differential axle side gears
56a, 56b together and thereby lock the axle shaft 32a, 32b. The locking
differential clutch 64 is collapsed by sealed pistons 66 (illustrated
schematically) located between a split differential spider 44'.
Pressurized fluid is communicated through apertures 68 located through the
length of the legs of the split differential spider 44'. The on-demand
functionality is achieved by control logic within the controller 62 which
applies pressure to the sealed pistons 66 whenever wheel slip is detected.
The foregoing description is exemplary rather than defined by the
limitations within. Many modifications and variations of the present
invention are possible in light of the above teachings. The preferred
embodiments of this invention have been disclosed, however, one of
ordinary skill in the art would recognize that certain modifications would
come within the scope of this invention. It is, therefore, to be
understood that within the scope of the appended claims, the invention may
be practiced otherwise than as specifically described. For that reason the
following claims should be studied to determine the true scope and content
of this invention.
*
