U.S. patent application number 10/340950 was filed with the patent office on 2005-01-13 for method of sealing low/reverse piston fluid circuit within an automatic transmission case.
Invention is credited to Rowell, Brian G..
Application Number | 20050005730 10/340950 |
Document ID | / |
Family ID | 33518837 |
Filed Date | 2005-01-13 |
United States Patent
Application |
20050005730 |
Kind Code |
A1 |
Rowell, Brian G. |
January 13, 2005 |
METHOD OF SEALING LOW/REVERSE PISTON FLUID CIRCUIT WITHIN AN
AUTOMATIC TRANSMISSION CASE
Abstract
An apparatus and method for repairing hydraulic fluid leakage
from the low/reverse gear fluid circuit of an automatic
transmission case is disclosed. The present repair kit comprises a
deformable grommet seal used in combination with a steel shim to
replace the original equipment gasket, which is the source of the
fluid leakage. Installation of the steel shim compresses the
grommet seal in the fluid passage thereby creating a leakproof seal
and maintaining the integrity of the low/reverse piston fluid
circuit. In addition, the steel shim functions as a spacer in
replacement of the original equipment manufacture gasket, which is
discarded, and also provides a non-compressible backing surface to
prevent distortion of the piston retainer when it is assembled and
fastened against the shim.
Inventors: |
Rowell, Brian G.; (Saxtons
River, VT) |
Correspondence
Address: |
SONNAX INDUSTRIES INC.
AUTOMATIC DRIVE
P.O. BOX 440
BELLOWS FALLS
VT
05101-0440
US
|
Family ID: |
33518837 |
Appl. No.: |
10/340950 |
Filed: |
January 13, 2003 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
60348262 |
Jan 15, 2002 |
|
|
|
Current U.S.
Class: |
74/606R ;
475/128 |
Current CPC
Class: |
F16H 61/0009 20130101;
Y10T 74/2186 20150115; F16H 2057/0068 20130101; Y10T 29/4973
20150115 |
Class at
Publication: |
074/606.00R ;
475/128 |
International
Class: |
F16H 031/00; F16H
057/02 |
Claims
1. A method of repairing hydraulic leakage from the low/reverse
piston fluid circuit of an automatic transmission case wherein the
transmission case includes a piston retainer attached to an
interior surface thereof in fluid communication with a fluid
passage formed in the transmission case, said piston retainer
defining a piston chamber wherein hydraulic fluid is delivered
under pressure to actuate a low/reverse clutch of said
transmission, said fluid passage being sealed by a gasket disposed
intermediate said piston retainer and said transmission case, said
method comprising the steps of: removing said piston retainer and
said gasket from said transmission case; inserting a grommet seal
into the fluid passage in fluid communication with said piston
retainer; replacing said gasket with a steel shim having the
approximate dimensions of said gasket; and reinstalling said piston
retainer such that said grommet seal is captured between said steel
shim and the transmission case, said grommet seal, said steel shim,
and said piston retainer being disposed in fluid communication with
the fluid passage providing a leakproof low/reverse piston fluid
circuit.
2. The method of claim 1 wherein the step of reinstalling further
includes the steps of: correcting any distortion in the surface of
said piston retainer that abuts said steel shim; fastening said
piston retainer to the transmission case; and compressing said
grommet seal within the fluid passage with said steel shim such
that a leakproof seal is formed therebetween.
3. The method of claim 2 wherein the step of fastening is carried
out by a torque wrench applying in the range of 25 to 50 inch
pounds of torque.
4. A repair kit for sealing the low/reverse piston fluid circuit of
an automatic transmission case wherein the transmission case
includes a piston retainer attached to an interior surface thereof
in fluid communication with a fluid passage formed in the
transmission case comprising: a circular shim having a central
opening conforming to the approximate dimensions of the piston
retainer, said shim including a fluid port for installation in
fluid communication with the fluid passage; and deformable sealing
means for installation within said fluid passage in fluid
communication with the piston retainer, said deformable sealing
means comprising a grommet seal fabricated from a fluorocarbon
rubber material said grommet seal having a flattened cylindrical
construction including a central opening for alignment within said
fluid passage, said grommet seal further including a perpendicular
flange member having an outwardly tapered outer edge portion, said
sealing means being disposed intermediate said shim and the
transmission case.
5. (canceled)
6. (canceled)
7. (canceled)
8. The repair kit of claim 4 wherein said shim includes a pattern
of bolt holes formed therein at a predetermined locations for
alignment with a matching pattern of threaded holes formed in the
transmission case.
9. The repair kit of claim 8 wherein said fluid port is positioned
at a predetermined angular relationship to said pattern of bolt
holes.
10. The repair kit of claim 8 wherein said shim is constructed of
sheet steel material in the range of 0.018 to 0.024 inches
thickness.
11. A repair kit for sealing the low/reverse piston fluid circuit
of an automatic transmission case wherein the transmission case
includes a piston retainer attached to an interior surface thereof
in fluid communication with a fluid passage formed in the
transmission case comprising: a circular shim having a central
opening conforming to the approximate dimensions of the piston
retainer, said shim including a fluid port for installation in
fluid communication with the fluid passage, said shim further
including a pattern of bolt holes formed therein at predetermined
locations for alignment with a matching pattern of threaded holes
formed in the transmission case; and a deformable grommet seal
having a flattened cylindrical construction including a central
opening for installation in fluid communication with the fluid
passage and disposed intermediate said shim and the transmission
case.
12. (canceled)
13. The repair kit of claim 11 wherein said fluid port is
positioned at a predetermined angular orientation to said pattern
of threaded holes.
14. The repair kit of claim 13 wherein said shim is constructed of
sheet steel material in the range of 0.018 to 0.024 inches
thickness.
15. The repair kit of claim 11 wherein said grommet seal is
fabricated of a fluorocarbon rubber material.
16. The repair kit of claim 15 wherein said grommet seal includes a
perpendicular flange member having an outwardly tapered outer edge
portion.
17. An improved low/reverse piston retainer assembly for use in
combination with an automatic transmission case including a
low/reverse piston disposed within a piston retainer, wherein the
piston retainer is attached to an interior surface of the
transmission case in fluid communication with the low/reverse fluid
passage formed in the transmission case, wherein the piston
retainer defines a piston chamber into which hydraulic fluid is
delivered under pressure from the fluid passage, the improvements
comprising: a steel shim conforming to the approximate dimensions
of the piston retainer, said shim including a fluid port disposed
in fluid communication with the fluid passage; and deformable
sealing means for installation within said fluid passage in fluid
communication with the piston retainer, said sealing means being
disposed intermediate said shim and the transmission case.
18. The improved low/reverse piston retainer assembly of claim 17
wherein said deformable sealing means comprises a grommet seal
having a flattened cylindrical construction including a central
opening for insertion within the fluid passage intermediate said
shim and the transmission case.
19. The improved low/reverse piston retainer assembly of claim 18
wherein said grommet seal is fabricated from a fluorocarbon rubber
material.
Description
CROSS-REFERENCE TO RELATED APPLICATION
[0001] This patent application claims the benefit under 35 U.S.C.
119(e) of U.S. Provisional Patent Application No. 60/348,262 filed
Jan. 15, 2002, entitled Method of Sealing Low/Reverse Piston Fluid
Circuit.
BACKGROUND OF INVENTION
[0002] The present invention relates generally to automatic
transmission systems and, more particularly, to a method of sealing
the low/reverse gear fluid circuit within an automatic transmission
case utilizing a grommet seal in combination with a steel shim in
place of an original equipment manufacture (hereinafter "OEM")
gasket.
[0003] A common service complaint in Chrysler A604 (40TE, 41TE)
automatic transmissions (hereinafter "Chrysler transmissions)
involves a poorly functioning and/or worn out low/reverse clutch
resulting from automatic transmission fluid (hereinafter "ATF")
leakage in the low/reverse piston fluid circuit. Such fluid leakage
is problematic in the aforementioned Chrysler transmissions because
of the design of the low/reverse piston retainer. Instead of being
machined into the transmission case as in previous automatic
transmission designs, the low/reverse piston retainer is a stamped
steel construction that is mounted on the interior surface of the
transmission case being spaced apart therefrom by a relatively
thin, flexible gasket. As a result the piston retainer has a
tendency to distort due to its thin-walled construction even when
the machine bolts, which secure it to the transmission case, are
applied with the specified torque (i.e. 40 inch/pounds) against the
flexible gasket. Thus, the OEM gasket, which is intended to seal an
ATF feed passage extending through the piston retainer and gasket
and into the transmission case, is insufficient to maintain the
integrity of this fluid circuit and results in ATF leakage at the
mating surfaces thereof.
DESCRIPTION OF RELATED PRIOR ART
[0004] One example of a prior art invention that attempts to remedy
this problem is shown in U.S. Pat. No. 5,619,888 to Anthony which
discloses a reinforcement member for a piston retainer in the form
of an arcuate plate for installation within the piston retainer
adjacent the ATF feed passage. Although the arcuate reinforcement
member provides for increased pressure and surface area for
contacting the fluid actuator adjacent the ATF feed passage, it
does not extend completely around the surface of the piston
retainer. This technique still requires compression of the gasket
material to seal around the ATF feed passage, which is the root
cause of the leakage. Thus, distortion of the sheet metal piston
retainer and subsequent fluid leakage can still occur.
[0005] Accordingly, the present invention has been developed to
resolve this problem and other shortcomings of the prior art.
SUMMARY OF THE INVENTION
[0006] The present invention provides a repair method and apparatus
comprising a fluorocarbon grommet seal for installation within the
subject ATF feed passage in the transmission case in combination
with a steel shim, which compresses the seal in position and
maintains the integrity of the low/reverse piston fluid circuit.
The steel shim functions as a spacer in substitution for the OEM
gasket and also provides a non-compressible backing surface to
prevent distortion of the piston retainer when installed. Thus, by
removing the OEM gasket from the interface of the piston retainer
and the transmission case, the cause of the ATF leakage is
eliminated.
[0007] Other features and technical advantages of the present
invention will become apparent from a study of the following
description and the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0008] The novel features of the present invention are set forth in
the appended claims. The invention itself, however, as well as
other features and advantages thereof will be best understood by
reference to the following detailed description of an illustrative
embodiment when read in conjunction with the accompanying figures,
wherein:
[0009] FIG. 1A is a cross-sectional view of a transmission case
labeled Prior Art illustrating the low/reverse piston and piston
retainer and showing the location of the OEM gasket;
[0010] FIG. 1B is an enlarged cross-sectional view taken along
section line 1B-1B of FIG. 1A illustrating the leakage mode of the
Prior Art piston retainer;
[0011] FIG. 2 is an enlarged cross-sectional view of the
transmission case of FIG. 1 illustrating the low/reverse piston and
piston retainer showing the location of the replacement steel shim
and grommet seal of the present invention;
[0012] FIG. 3A is a cross-sectional view of the grommet seal of the
present invention;
[0013] FIG. 3B is an elevational view of the present grommet
seal;
[0014] FIG. 4 is an elevational view of the steel shim of the
present invention;
[0015] FIG. 5A is a perspective view illustrating the installation
procedure for the present grommet seal and steel shim;
[0016] FIG. 5B is a perspective view illustrating the installation
of the OEM piston retainer onto the present steel gasket and
grommet seal;
[0017] FIG. 6A is an enlarged cross-sectional view taken along
section line 6A-6A of FIG. 2 illustrating the present invention in
the process of being assembled; and
[0018] FIG. 6B is an enlarged cross-sectional view taken along
section line 6B-6B of FIG. 2 illustrating the integrity of the seal
in a completed installation.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0019] Prior to describing the present invention in detail, it may
be useful to briefly review the structure and function of the
low/reverse piston and piston retainer of the Chrysler A604
transmission wherein the present invention is utilized. Although
the following disclosure is directed primarily to the Chrysler A604
transmission for purposes of explanation, it will be understood
that the present inventive concept is applicable to transmissions
of other manufacturers having a similar configuration and, as such,
are considered to be within the scope of the present invention.
[0020] With reference to the drawings there is shown therein a
prior art Chrysler A604 low/reverse piston, indicated generally at
100, installed within a piston retainer, indicated generally at
110, and illustrated in FIG. 1A. The OEM piston retainer 110 is a
stamped sheet metal construction, which is designed to receive the
low/reverse piston 100 in sliding engagement therein. Internal and
external lip seals 102, 104 respectively provide a hydraulic seal
for the piston chamber 105 to actuate the low/reverse clutch.
[0021] More particularly, when the low/reverse piston 100 is
actuated, ATF flows into piston chamber 105 from the fluid passage
109 formed in the transmission case 115, through the gasket 112,
and through the inlet opening 106 formed in the low/reverse piston
retainer 110. ATF fills the piston chamber 105 applying pressure to
the piston 100 to engage the low/reverse clutches. It will be
understood that in the OEM design, the gasket 112 is disposed
between the piston retainer 110 and the transmission case 115 to
seal the inlet opening 106 and to maintain the integrity of the
fluid circuit. The OEM gasket 112 is fabricated from a composite
gasket material in the range of 0.018" to 0.024" thickness.
[0022] A problem exists with this design in that the stamped, sheet
metal construction of the low/reverse retainer 110 has a tendency
to distort (FIG. 1B) at the interface with the gasket 112 even if
machine bolts 114 are tightened with minimal torque (i.e. 40
inch/pounds), which is the recommended torque for this application.
This is because the low/reverse retainer 110 is too thin to be
supported by a flexible gasket 112 in this particular application.
Thus, it is common for ATF leakage to occur as at 111 at the
juncture of the inlet opening 106 and the gasket 112 as seen in
FIG. 1B. As a result there is insufficient ATF flow to the
low/reverse clutches, which can cause delayed engagement, chatter
and slippage of the clutches and eventually complete failure.
[0023] Accordingly, the present invention has been developed to
resolve this problem and will now be described. Referring to FIG. 2
the present invention provides a repair kit and method of use
including a circular steel shim 120 in substitution for the OEM
gasket 112 and a sealing means, which are utilized in combination
to remedy the leakage problem. The present invention provides a
deformable sealing means including, but not limited to, the
following structures. A grommet seal 125, which is fabricated from
fluorocarbon rubber or other material suitable for this
application, has been designed for insertion directly into the ATF
feed passage 109 as shown in FIG. 2.
[0024] As more clearly shown in FIGS. 3A and 3B, grommet seal 125
is a generally flattened cylindrical construction having a central
bore 126. In the embodiment shown grommet seal 125 includes a
perpendicular flange 125a integrally formed thereon, which further
includes a tapered outer edge portion 125a' that renders it more
easily compressed after installation within fluid passage 109
(FIGS. 6A and 6B).
[0025] In the present invention a steel shim 120 as most clearly
shown in FIG. 4 replaces the OEM gasket 112. In the preferred
embodiment the shim 120 is constructed of sheet steel in the range
of 0.018" to 0.024". The shim 120 functions to support the mating
surface of the piston retainer 110 maintaining it in a flat
condition to prevent distortion thereof and also functions as a
spacer in substitution for the OEM gasket 112.
[0026] Still referring to FIG. 4, it can be seen that the steel
shim 120 is a flattened, circular construction having a central
opening 123 and conforms to the approximate dimensions of the
mating surface of the piston retainer 110 and the OEM gasket 112.
Shim 120 is provided with an ATF port 122 conforming approximately
to the O.D. dimension of the perpendicular flange 125a of the
grommet seal 125. Shim 120 is also provided with a pattern of three
bolt holes 124 formed in predetermined locations corresponding to
threaded holes 127 (FIG. 5A) formed in the transmission case
115.
[0027] In an assembly procedure of the present invention grommet
seal 125 is initially pressed into the fluid passage 109 such that
the flange 125a faces up as shown in FIG. 5A. Next, the steel shim
120 is placed in position such that the ATF port 122 is disposed in
alignment with grommet seal 125 and threaded holes 127. Next, the
OEM piston retainer 110 is reinstalled onto the steel shim 120 and
machine screws 114 are replaced in threaded holes 127 as shown in
FIG. 6A. Thereafter, machine screws 114 are tightened to the
specified torque and the grommet seal 125 is compressed against the
mating surfaces of the piston retainer 110, the steel shim 120, and
the transmission case 115 to affect a leakproof installation as
shown in FIG. 6B.
[0028] It will be appreciated by those skilled in the art that by
securing the piston retainer 110 against the surface of the steel
shim 120, any distortion of its sheet metal structure is
effectively eliminated. Thus, the leakage problem at the juncture
of the piston retainer 110 and the transmission case 115 is
resolved and the integrity of the fluid circuit is maintained.
[0029] Although not specifically illustrated in the drawings, it
should be understood that additional equipment and structural
components will be provided as necessary and that all of the
components described above are arranged and supported in an
appropriate fashion to form a complete and operative method of
sealing the low/reverse piston retainer fluid circuit incorporating
features of the present invention.
[0030] Moreover, although illustrative embodiments of the invention
have been described, a latitude of modification, change, and
substitution is intended in the foregoing disclosure, and in
certain instances some features of the invention will be employed
without a corresponding use of other features. Accordingly, it is
appropriate that the appended claims be construed broadly and in a
manner consistent with the scope of invention.
* * * * *