U.S. patent application number 09/851711 was filed with the patent office on 2002-11-14 for pneumatic three-position shift mechanism with fewer components.
This patent application is currently assigned to Meritor Heavy Vehicle Technology, LLC. Invention is credited to Bennett, John L., Larsen, Herbert A..
Application Number | 20020166402 09/851711 |
Document ID | / |
Family ID | 25311461 |
Filed Date | 2002-11-14 |
United States Patent
Application |
20020166402 |
Kind Code |
A1 |
Bennett, John L. ; et
al. |
November 14, 2002 |
PNEUMATIC THREE-POSITION SHIFT MECHANISM WITH FEWER COMPONENTS
Abstract
An improved transfer case has fewer parts than the prior art to
achieve the pneumatic three-position function. In the prior art the
pneumatic cylinders were provided by bolt-on housings which
required additional components to achieve a fluid tight connection.
The present invention incorporates its fluid cylinders within bores
formed into the transfer case housings. In this way, the required
number of housing components is greatly reduced compared to the
prior art.
Inventors: |
Bennett, John L.; (Fraser,
MI) ; Larsen, Herbert A.; (Clarkston, MI) |
Correspondence
Address: |
Theodore W. Olds, Esq.
Carlson, Gaskey & Olds, P.C.
Suite 350
400 W. Maple
Birmingham
MI
48009
US
|
Assignee: |
Meritor Heavy Vehicle Technology,
LLC
|
Family ID: |
25311461 |
Appl. No.: |
09/851711 |
Filed: |
May 9, 2001 |
Current U.S.
Class: |
74/473.37 |
Current CPC
Class: |
F16H 2061/307 20130101;
F16H 63/3023 20130101; F16H 61/30 20130101; Y10T 74/20183 20150115;
Y10T 74/20024 20150115 |
Class at
Publication: |
74/473.37 |
International
Class: |
B60K 001/00; B60K
020/00 |
Claims
1. A vehicle transfer case comprising: a shift collar movable with
a shift rod between three positions, with said shift collar
selectively engaging a low speed gear and a high speed gear in two
positions and being in a neutral position in a third position; a
housing for housing said shift rod, and said high speed and low
speed gear, said housing comprising two housing halves; and a fluid
shift mechanism for driving said shift rod between three positions
corresponding to said low speed, said high speed and said neutral
position, said shift rod being driven by pistons at a first end of
said shift rod, and moving with said shift rod within fluid
chambers, and there being pressurized fluid supplies for
selectively directing pressurized fluid to said chambers, and at
least a portion of said chambers being formed by an open bore
within a first of said housing halves.
2. A transfer case as recited in claim 1, wherein a second end of
said shift rod remote from said first end of said shift rod moves
within a blind bore formed integrally within a second of said
housings.
3. A transfer case as recited in claim 1, wherein there are a pair
of said pistons movable with said shift rod, with one of said
pistons being movable relative to said shift rod in one direction,
but moving with said shift rod when said other of said pistons
moves in said second direction, and one of said pistons being fixed
to move with said shift rod.
4. A transfer case as recited in claim 3, wherein said second
piston which is fixed to move with said shift rod moving only
within said open bore in said first housing.
5. A transfer case as recited in claim 4, wherein said open bore
extends to an open end, and an end cap being secured within said
open end.
6. A transfer case as recited in claim 4, wherein said second
piston moves within said end cap, but is within an axial extent of
said open bore in said first housing for at least a portion of
movement to achieve one of said three positions.
7. A transfer case as recited in claim 4, wherein said bore has
three inner diameters, with the first inner diameter receiving said
second piston and a portion of said first piston, an enlarged
portion of said second piston moving within a second outer diameter
bore, and said end cap being received within said third outer
diameter bore portion.
8. A vehicle transfer case comprising: a shift collar movable with
a shift rod between three positions, with said shift collar
selectively engaging a low speed gear and a high speed gear in two
positions and being in a neutral position in a third position; a
housing for housing said shift rod, and said high speed and low
speed gear, said housing comprising two housing halves; and a fluid
shift mechanism for driving said shift rod between three positions
corresponding to said low speed, said high speed and said neutral
position, said shift rod being driven by pistons to a first end of
said shift rod, and moving with said shift rod within fluid
chambers, and there being pressurized fluid supplies for
selectively directing pressurized fluid to said chambers, and at
least a portion of said chambers being formed by an open bore
within a first of said housing halves, a blind bore within a second
of said housing halves receiving a second end of said shift rod,
with a pair of pistons movable with said shift rod, one of said
pistons being movable relative to said shift rod in one direction,
and a second of said pistons being fixed to move with said shift
rod, said second of said pistons moving only within said open bore
in said housing between said three positions.
9. A transfer case as recited in claim 8, wherein said open bore
extends to an open end, and an end cap being secured within said
open end.
10. A transfer case as recited in claim 8, wherein said second
piston moves within said end cap, but is within an axial extent of
said open bore in said first housing for at least a portion of
movement to achieve one of said three positions.
11. A transfer case as recited in claim 8, wherein said bore has
three inner diameters, with the first inner diameter receiving said
second piston and a portion of said first piston, an enlarged
portion of said second piston moving within a second outer diameter
bore, and said end cap being received within said third outer
diameter bore portion.
Description
BACKGROUND OF THE INVENTION
[0001] This invention relates to a pneumatic three-position shift
mechanism for use in vehicle transfer cases wherein the number of
components to provide the shift mechanism is reduced compared to
the prior art.
[0002] Vehicle transfer cases are typically provided with the
ability to move a shift yoke between a first position at which is
engages a low speed gear, a second position at which it engages a
high speed gear, and a third intermediate neutral position at which
neither gear is engaged. Typically, these systems have incorporated
a shift rod that is movable within a two-part housing between the
three positions. At one end of the shift rod are a pair of
cylinders movable within three different chambers and between the
several positions. At the opposed end of the shift rod is a guiding
chamber in which the shift rod is movable.
[0003] In the prior art, all of the fluid chambers are provided by
separate housings which are bolted to the main transfer case
housings. With each separate housing, the number of seals and fluid
tight connections that must be utilized increases. Thus, with the
prior art, there are required seals and securing devices for
separate fluid housings at each of the two ends of the transfer
case.
[0004] FIG. 1 shows an example 20 of the prior art transfer case. A
housing 22 has a split line 24 dividing two housings sub-portions
26 and 28. A shift rod 30 is received extending between the two,
and moves a shift collar 32 to selectively engage one of the two
gears 34 and 36. Gear 34 is a low speed and gear 36 is a high speed
gear. The collar 32 is shown in the intermediate or neutral
position.
[0005] A fluid cylinder 38 is bolted to one end of the housing 28.
The other housing portion 26 receives the bolted on fluid housing
40. Housing 40 receives the rear end 42 of the shift rod 30 and
housing 38 receives the forward end 44 which moves with a plurality
of pistons to achieve the various positions of the collar 32.
[0006] As can be appreciated, with the separate housings 38 and 40
a good deal of additional attachments, seals, etc. are
necessary.
SUMMARY OF THE INVENTION
[0007] In the disclosed embodiment of this invention, the chambers
for receiving both the piston and preferably the remote end of the
shift rod are formed by integral bores in the transfer case
housings. In this way, the bores are self-sealed, and no separate
sealing elements or elaborate fluid-type securing devices are
necessary.
[0008] In a preferred embodiment of this invention, both of the
chambers are formed by bores. The bore for receiving a remote end
is preferably a blind bore extending into the housing. The bore for
receiving the piston end of the shift rod is preferably a bore
which opens outwardly through a plurality of stepped bore portions.
One of the pistons is preferably of a larger diameter and is
movable within a first stepped portion. An end cap is received with
a second outer diameter stepped portion of the bore, and provides
the outer end for the fluid cylinder. This cap is all that need be
secured to the housing in a fluid tight manner. As can be
appreciated, the present invention thus greatly reduces the number
of required components.
[0009] These and other features of the present invention can be
best understood from the following specification and drawings, the
following of which is a brief description.
BRIEF DESCRIPTION OF THE DRAWINGS
[0010] FIG. 1 shows the prior art.
[0011] FIG. 2 shows the inventive transfer case in a low speed
position.
[0012] FIG. 3 shows the inventive transfer case in a high speed
position.
[0013] FIG. 4 shows the inventive transfer case in a neutral
position.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
[0014] An inventive transfer case 50 is illustrated in FIG. 2
having a first fluid connection 52 for supplying a first
pressurized fluid, preferably air, a second fluid connection 54 and
a third fluid connection 56. Third connection 56 supplies
pressurized air selectively to a chamber 58, connection 54 supplies
pressure to a chamber 60 and supply 52 selectively supplies
pressurized air to a chamber 62. The attachment of the air to each
of the three inputs 52, 54, and 56 selectively drive the shift rod
64 in a manner that is not distinct from that of the prior art. A
remote end 66 of the shift rod 64 moves within a blind bore 67
within housing element 55. The other end 68 of the shift rod 64
selectively moves with a pair of pistons 70 and 72 between the
various positions as will be clear between FIGS. 2-4. The bore 73
for receiving the piston is formed as an integral bore within the
housing component 53. An end cap 74 closes off the bore 73, and
carries the fluid connection 52. Seals 76 are positioned between
the piston 72 and 70 and the cap 74, and housing 53 as
appropriate.
[0015] As can be seen, the piston 70 has an enlarged radially outer
portion 81 which is received within a portion 78 of the bore 73. A
second enlarged portion 80 of the bore 73 receives the outer
periphery of the end cap 74.
[0016] The use of the bores 72 in the housing 53 and the bore 67 in
the housing 55 eliminates the required separate housings of the
prior art, and greatly minimizes the components necessary to
provide the shift mechanism. FIG. 2 shows the collar 65 in a
position such that the low speed gear 34 is engaged.
[0017] FIG. 3 shows the pistons 72 and 70 shifted to the right from
the position shown in FIG. 2, and the shift collar 65 is now
engaged on the high speed gear 36. As can be appreciated, the
entirety of movement of the piston 72 is within the bore 73 between
these two extreme positions. Moreover, as can be appreciated
between the FIG. 2 and FIG. 3 position, while the enlarged portion
81 of the piston 72 has now moved outwardly beyond a forward end 85
of the bore, in the FIG. 2 position the enlarged piston 70 is
within the bore, and to the left and forward of 85.
[0018] FIG. 4 shows the neutral position at which the shift collar
65 is at an intermediate position. As can be appreciated, the
smaller piston 72 is still fully within the bore 83. The enlarged
portion 81 of the piston 70 is still forward of the end 85.
[0019] As can be appreciated, by selectively controlling the flow
of pressurized fluid to the supply taps 52, 54 and 56 the pistons
can be moved to the various positions and the resulting movement of
the shift rod 64 and collar 65 can be achieved. As can be
appreciated, the piston 70 can slide relative to the shift rod 64.
Thus, when the rod is being driven to the high gear position such
as shown in FIG. 3, pressurized fluid is delivered to taps 54 and
56, but not to tap 52. This causes the piston 70 to move to the
right along the shift rod to the position such as shown in FIG. 3.
When moving the shift rod to the neutral position shown in FIG. 4,
fluid is delivered generally to the tap 54, but not the taps 52 and
56. This drives the piston 72 to the left and to the FIG. 4
position. Finally, when moving back to the FIG. 2 position,
pressurized fluid is delivered to tap 52, but not taps 54 and 56.
The piston 70 initially moves to the left along the shift rod 64,
but once it abuts the piston 72, the entirety of the shift rod 64
and the pistons 72 and 70 move to the left since the piston 70 will
abut the piston 72, which in turn abuts a collar 100 on the shift
rod 64.
[0020] Although a preferred embodiments of this invention have been
disclosed, a worker in this art would recognize that certain
modifications would come within the scope of this invention. For
that reason the following claims should be studied to determine the
true scope and content of this invention.
* * * * *