CA2195514A1 - Transmission band with anchor bracket having local coining at the anchor hole - Google Patents
Transmission band with anchor bracket having local coining at the anchor holeInfo
- Publication number
- CA2195514A1 CA2195514A1 CA002195514A CA2195514A CA2195514A1 CA 2195514 A1 CA2195514 A1 CA 2195514A1 CA 002195514 A CA002195514 A CA 002195514A CA 2195514 A CA2195514 A CA 2195514A CA 2195514 A1 CA2195514 A1 CA 2195514A1
- Authority
- CA
- Canada
- Prior art keywords
- reaction
- brake band
- bracket
- perimeter edge
- prestressed
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Abandoned
Links
Classifications
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16D—COUPLINGS FOR TRANSMITTING ROTATION; CLUTCHES; BRAKES
- F16D65/00—Parts or details
- F16D65/02—Braking members; Mounting thereof
- F16D65/04—Bands, shoes or pads; Pivots or supporting members therefor
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16D—COUPLINGS FOR TRANSMITTING ROTATION; CLUTCHES; BRAKES
- F16D65/00—Parts or details
- F16D65/02—Braking members; Mounting thereof
- F16D65/04—Bands, shoes or pads; Pivots or supporting members therefor
- F16D65/06—Bands, shoes or pads; Pivots or supporting members therefor for externally-engaging brakes
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16H—GEARING
- F16H45/00—Combinations of fluid gearings for conveying rotary motion with couplings or clutches
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16H—GEARING
- F16H57/00—General details of gearing
- F16H57/08—General details of gearing of gearings with members having orbital motion
- F16H57/10—Braking arrangements
Landscapes
- Engineering & Computer Science (AREA)
- General Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- Braking Arrangements (AREA)
Abstract
A transmission band (10) for use in automatic transmissions having an elongated strap member (12) of annular configuration. The strap member (12) includes an apply bracket (18) and a reaction bracket (20). The reaction bracket (20) has a generally domed (36) configuration and includes a reaction opening (32) having a perimeter edge prestressed (40) about at least a portion of its circumference.
Description
' 2195514 DESCRIPTION
TRANSMISSION BAND WITH ANCHOR BRACKET
HAVING LOCAL COINING AT THE ANCHOR HOLE
RE~ATED APPLICATIONS
This application is a continuation-in-part of co-pending application Serial No.08/162,495, filed December 3,1993, which is a continuation-in-part of application Serial No.08/006,324, filed January 19,1993 and application Serial No. 07/960,994, filed October 14, 1992, now both abandoned. Application Serial No. 07/960,994 is a continuation of application Serial No. 07/784,537, filed October 29, 1991, now abandoned. The subject matter of application Serial Nos. 08/162,495, 08/006,324, 07/960,994 and 07/784,537 are expressly incorporated herein by reference in their entirety.
TECHNICAL FIELD
This invention relates to a transmission brake band utilized in a vehicle automatic transmission, wherein the bands encompass one or more clutch drives and, under the influence of suitable hydraulic controls, effect ~ear changes and control the direction of rotation of tho output or drive shaft from the transmission.
BACKGROUNI;) OF THE INVENTION
In conventional vehicle automatic transmissions of the torque converter type, a driving shaft extends from the torque converter into the transmission housin~ to a unit havin~ one or more clutch drums around which are arranged either sin~le wrap or double wrap brake bands. It is the function of the brake band through the application of suitable hydraulic controls to effect gear changes and control the direction of the rotation of the output shaft from the transmission to the differential for the drivin~ wheels of the vehicle.
Brake band research has recently focused on the provision of bands which are composed of li~htweight materials of reduced cross-se~tional thicknesses, thereby optimizin~ wei~ht characteristics while yet retainin~ desi~n requirements for the fatigue life of the bands. Generally, the failure of a brake band will occur at either the actuation or apply bracket or the reaction or anchor bracket. It is a requisite that each brake band have an actuation or apply bracket for receivin~ an apply piston and a reaction or anchor bracket which operatively receives a reaction member located in the transmission. Various types of automatic transmissions utilize different types of reaction members. Some reaction members may be of the tan~ential type which comprise a stationary plun~er or stop member actin~ a~ainst the anchor end of the brake band, while other reaction members may be the reaction pin type where the pin is positioned perpendicular to the clutch drum and strap member and extends into a reaction openin~ located in the anchor bracket of the brake band.
An improved reaction or anchor bracket intended for use with the reaction pin type is disclosed in the United States Patent No. 5,381;876, wherein the anchor bracket includes a dome portion surroundin~ the reaction openin~ which is formed as a blanked hole by punchin~ or piercin~ the bracket material. The reaction bracket of the '876 patent is commonly formed from a double thickness of strap material which is expanded and prestressed in part to create a dome configuration. The expansion operation prestresses the strap material at the location where the strap material is deformed to create the dome, thereby providin~
somewhat enhanced stren~th characteristics to the dome anchor. The dome is at the same time pierced or punched to form a blanked hole to produce the reaction hole opening in the non-stressed strap material which is centered in the dome. The dome portion surroundin~ the 21 ~55t ~
reaction openin~ places is formed from strap material which is in a ~enerally perpendicular relationship to the reaction pin as it is inserted into the reaction openin~.
Problems have been encountered with the anchor bracket structure tau~ht by United States Patent No. 5,381,876 when hi~h loads are used with the band. It has been discovered that current brake bands manufactured according to the teachin~s of the '876 patent have an approximately median life of 16,000 cycles when tested per the standard producticn fati~ue procedure which is 970 pounds of apply force and 140 foot pounds of torque. Failure will almost always occur at the blanked hole in the reaction member. It has been found that, even thou~h the domed portion is expanded and prestressed to create a dome confi~uration, the flattened portion of the band surroundin~ the blanked hole is not prestressed. The materials from which the hands are commonly constructed has a characteristic that allow the material to harden when it is formed or worked. Thus the material characteristics remain unchan~ed without a si~nificant amount of material flow or formin~ around the hole. Consequently, the prestress hardenin~
characteristics do not apply until areas are reached where the strap material has been expanded to create the dome.
Therefore, it is the object of the is invention to provide an improvement to the domed anchor bracket disclosed in United States Patent No. S,381,876.
It is yet another object of this invention to provide work hardenin~
of the anchor bracket in the proximity of the anchor or reaction hole to improve the fati~ue stren~th of the anchor bracket.
It is yet another object of the invention to provide localized prestressin~ of the bracket material about the anchor hole.
BRIEF DESCRIPTION OF THE INVENTION
The present invention provides an improved anchor bracket for use with automatic transmission brake bands. The bracket includes a dome having hardened or prestressed areas surrounding the reaction opening 5 which is formed as a blanked hole by punching or piercing the bracket material. The bracket of the invention is herein described generally with re~ard to its incorporation with a single piece brake band, however, it is envisioned that the bracket of this invention may be utilized with any brake band desi~n where prestressed or work-hardened areas 10 surroundin~ the reaction holes are needed. For the purposes of simplicity in explanation of the invention, the present invention will be described herein as used with a sin~le strip of suitable metallic band material, wherein the anchor bracket portion is integrally formed therefrom.
A typical brake band maybe formed in accordance with the processes tau~ht by United States Patent No. 5,381,876. Once the domed reaction bracket is formed, the peripheral surface area surrounding the reaction openin~ is ~enerally aligned in parallel with the curvilinear surface of the remainder of the band. The dome portion surrounding the reaction opening places the strap material into a 20 ~enerally perpendicular relationship with the reaction pin as it is inserted in the reaction opening. There is not a significant amount of rnaterial flow or working in forming on the hole, consequently the strength improving characteristic of the band material is usually not utilized at the locations where most stresses from hand operation are focused. Thus, 25 ~he present invention provides that the ed~e of the anchor hole be coined or work hardened to prestress the material and improve the material strength of the anchor bracket and thus, improve its fatigue life.
Typical brake bands of the type of the present invention are manufactured from SAE grade 980-XF material. One of the beneficial 30 characteristics of the SAE ~rade 980-XF metal is its work hardenin~
capability. Initially, the material is formable, but as the material is ~195514 formed, it ~ains stren~th in the formed areas. Therefore, the present invention provides for work hardenin~ or ~coinin~ of the perimeter ed~e surroundin~ the anchor hole to improve the material strength of the anchor hole and thus, improve its fati~ue life.
The inventii~n will be more readily understood after readin~ the followin~ best mode for carryin~ out the invention with reference to the accompanyin~ drawin~s.
BRIEF DESCRIPTION OF THE DRAWINGS
Fi~. 1 is an elevated side view of the transmission brake band of the present invention.
Fi~. 2 is a partial top plan view of the reaction bracket for the transmission brake band of Fi~. 1.
Fi~. 3 is a sectional view taken alon~ lines 3-3 of Fi~. 2.
Fi~. 4 is a partial top plan view of a first alternative embodiment of the reaction bracket of the transmission brake band of Fi~. 1.
Fi~. 5 is a sectional view taken alon~ lines 5-5 of Fi~. 4.
BEST MODF FOR CARRYING OUT THE INVFN~ION
Referrin~ now with particularity to the drawin~s, the present invention will be described in detail as a one-piece sin~le wrap brake band. However, it is not intended that this description of the invention in use with a sin~le wrap one-piece brake band be necessarily limitin~
upon the envisioned ran~e of the embodiments for the present invention.
Referrin~ now to Fi~. 1, a one-piece brake band ~enerally desi~nated by the reference No. 10 which is formed from an elon~ated strap of material 12 definin~ an annular band of determinant len~th. In the embodiment shown in Fi~. 1, the opposed ends 14, 16 of the strap 12 are folded over and rearwardly back upon the strap 12 to create bracket members 18, 20 desi~ned to en~aye an apply piston (not shown) and a reaction pin (not shown). The brake band further includes a ~1 955~ 4 friction linin~ (not shown~ suitably secured to the interior circumference 33 by an acceptable method of adhesion.
The apply bracket member 18 rnay be formed in any acceptable manner. The apply bracket member shown in Fi~. 1 is formed by foldin~
S the end 14 into an upwardly folded rid~e 26 havin~ a stren~thenin~ rib 28 on the side of the fold located below the contact point for an apply piston or pin. The folded rid~e 26 may or may not include a depressed area (not shown~ intended to form a pocket in the central area of the side opposite the stren~thenin~ rib 28. The depressed area is adapted to 10 enga~e the end of the apply piston actin~ in a ~enerally tangential direction to the clutch drum. The end 14 with rid~e 26 and stren~thenin~ rib 28 are folded over the strap 12 and secured to the strap, preferably in a simultaneous manufacturin~ step with the foldin~
and forming operation, by commonly accepted methods such as clinch 15 fastenin~ 30.
Referrin~ now to Fi~s. 2 and 3, the present invention resides in the end 16 which forrns the reaction bracket 20. The end 16 is formed by foldin~ the strap member 12 upwardly and rearwardly upon itself. The double layer of material is then subjected to an expansion and blankin~
20 operation which forms the dome 36 and creates the blanked hole or reaction openin~ 32. The surface area of the dome 36 surroundin~ the opening 32 is symrnetrically oriented to be substantially perpendicular to the axial center line formed by the reaction openin~ 32. Preferably, the blanked hole or reaction openin~ 32 includes four flats 34 such that the 25 reaction openin~ 32 is of a ~enerally square confi~uration. The flats 34 are ~enerally disposed in a 90~ relationship with one another and are joined with curved corners 38. Each of the flats 34 includes a work hardened or coined 40 area that extends the len~th of the flat 34. The work hardened area 40 is produced by compressin~ or coinin~ the strap 30 material proximate the flat 34, as shown in Fig. 3 by the arrow, to thereby reduce the cross-sectional thickness of the perimeter ed~e of 21 95~ 1 4 each flat 34. Work-hardenin~ or coinin~ thus stren~thens the strap material in the work hardened area 40. Preferably, the curvature of the coined or work hardened areas 40 matches the radial curvature of the corners 38 which act to join the flats 34 to~ether. The preferably width 5 of the coined area is .020 nches.
Referrin~ now to Fi~s. 4 and 5, an alternative embodiment of the present invention is disclosed. The alternative reaction bracket member 120 is formed by foldin~ the strap material 112 upwardly and rearwardly back upon itself. The double layer of strap material is subjected to an 10 expansion and piercin~ operation which forms a dome 136 and creates a blanked hole or reaction openin~ 132. The blanked hole or reaction openin~ 132 is circular in shape and the perimeter ed~e of the reaction openin~ 132 is work hardened or coined 140 about its entire circumference.
.
Exam~le A set of prototype bands built in accordance with the best mode of the present invention were compared with typical production bands made simultaneously from the same strip of steel and from the same 5 toolin~ set up so as to eliminate ;~ll variables other than the effects of work hardenin~ or coinin~. The fati~ue life of the bands, measured as the rnedian B10 life on the Weibul Distribution Fati~ue Analysis, built in accordance with the best mode of the present ;nvention and the typical production bands are shown in the followin~ table.
Table 1 Coined Bands Production Bands 73,900 54,200 68,900 44,000 56,900 33,900 55,300 30,700 47,500 30,000 1st Group 43,600 29,700 42,700 28,800 42,600 28,100 42,400 23,500 41,800 23,400 40,500 21,700 37,200 20,400 57,800 25,000 46,200 24,600 40,200 23,000 2nd Group 39,200 20,100 38,500 19,200 37,000 18,000 19,700 18,000 17,900 The data from the test ~roup shows an 80% increase in median B10 life by coinin~ or work-hardenin~ the anchor hole in accordance with the best mode of the present invention. For the coined bands, median B10 life was 28,424 cycles with a slope of 3.8. For the production bands, median B10 life was 15,787 ycles with a slope of 3.5. The slope measurement is indicative of the variability or distribution of results. The hi~her the slope number, the more narrow the band of variability or distribution and therefore, the more positive the results.
The work hardened and coined dome reaction bracket of the present invention provides for ~reater stren~th in retainin~ the reaction pin in position without premature failure of the brake band. It is intended that variations of the embodiments disclosed herein may be incorporated with reaction or apply brackets with transmission bands without the departin~ from the scope and content of the followin~ claims.
TRANSMISSION BAND WITH ANCHOR BRACKET
HAVING LOCAL COINING AT THE ANCHOR HOLE
RE~ATED APPLICATIONS
This application is a continuation-in-part of co-pending application Serial No.08/162,495, filed December 3,1993, which is a continuation-in-part of application Serial No.08/006,324, filed January 19,1993 and application Serial No. 07/960,994, filed October 14, 1992, now both abandoned. Application Serial No. 07/960,994 is a continuation of application Serial No. 07/784,537, filed October 29, 1991, now abandoned. The subject matter of application Serial Nos. 08/162,495, 08/006,324, 07/960,994 and 07/784,537 are expressly incorporated herein by reference in their entirety.
TECHNICAL FIELD
This invention relates to a transmission brake band utilized in a vehicle automatic transmission, wherein the bands encompass one or more clutch drives and, under the influence of suitable hydraulic controls, effect ~ear changes and control the direction of rotation of tho output or drive shaft from the transmission.
BACKGROUNI;) OF THE INVENTION
In conventional vehicle automatic transmissions of the torque converter type, a driving shaft extends from the torque converter into the transmission housin~ to a unit havin~ one or more clutch drums around which are arranged either sin~le wrap or double wrap brake bands. It is the function of the brake band through the application of suitable hydraulic controls to effect gear changes and control the direction of the rotation of the output shaft from the transmission to the differential for the drivin~ wheels of the vehicle.
Brake band research has recently focused on the provision of bands which are composed of li~htweight materials of reduced cross-se~tional thicknesses, thereby optimizin~ wei~ht characteristics while yet retainin~ desi~n requirements for the fatigue life of the bands. Generally, the failure of a brake band will occur at either the actuation or apply bracket or the reaction or anchor bracket. It is a requisite that each brake band have an actuation or apply bracket for receivin~ an apply piston and a reaction or anchor bracket which operatively receives a reaction member located in the transmission. Various types of automatic transmissions utilize different types of reaction members. Some reaction members may be of the tan~ential type which comprise a stationary plun~er or stop member actin~ a~ainst the anchor end of the brake band, while other reaction members may be the reaction pin type where the pin is positioned perpendicular to the clutch drum and strap member and extends into a reaction openin~ located in the anchor bracket of the brake band.
An improved reaction or anchor bracket intended for use with the reaction pin type is disclosed in the United States Patent No. 5,381;876, wherein the anchor bracket includes a dome portion surroundin~ the reaction openin~ which is formed as a blanked hole by punchin~ or piercin~ the bracket material. The reaction bracket of the '876 patent is commonly formed from a double thickness of strap material which is expanded and prestressed in part to create a dome configuration. The expansion operation prestresses the strap material at the location where the strap material is deformed to create the dome, thereby providin~
somewhat enhanced stren~th characteristics to the dome anchor. The dome is at the same time pierced or punched to form a blanked hole to produce the reaction hole opening in the non-stressed strap material which is centered in the dome. The dome portion surroundin~ the 21 ~55t ~
reaction openin~ places is formed from strap material which is in a ~enerally perpendicular relationship to the reaction pin as it is inserted into the reaction openin~.
Problems have been encountered with the anchor bracket structure tau~ht by United States Patent No. 5,381,876 when hi~h loads are used with the band. It has been discovered that current brake bands manufactured according to the teachin~s of the '876 patent have an approximately median life of 16,000 cycles when tested per the standard producticn fati~ue procedure which is 970 pounds of apply force and 140 foot pounds of torque. Failure will almost always occur at the blanked hole in the reaction member. It has been found that, even thou~h the domed portion is expanded and prestressed to create a dome confi~uration, the flattened portion of the band surroundin~ the blanked hole is not prestressed. The materials from which the hands are commonly constructed has a characteristic that allow the material to harden when it is formed or worked. Thus the material characteristics remain unchan~ed without a si~nificant amount of material flow or formin~ around the hole. Consequently, the prestress hardenin~
characteristics do not apply until areas are reached where the strap material has been expanded to create the dome.
Therefore, it is the object of the is invention to provide an improvement to the domed anchor bracket disclosed in United States Patent No. S,381,876.
It is yet another object of this invention to provide work hardenin~
of the anchor bracket in the proximity of the anchor or reaction hole to improve the fati~ue stren~th of the anchor bracket.
It is yet another object of the invention to provide localized prestressin~ of the bracket material about the anchor hole.
BRIEF DESCRIPTION OF THE INVENTION
The present invention provides an improved anchor bracket for use with automatic transmission brake bands. The bracket includes a dome having hardened or prestressed areas surrounding the reaction opening 5 which is formed as a blanked hole by punching or piercing the bracket material. The bracket of the invention is herein described generally with re~ard to its incorporation with a single piece brake band, however, it is envisioned that the bracket of this invention may be utilized with any brake band desi~n where prestressed or work-hardened areas 10 surroundin~ the reaction holes are needed. For the purposes of simplicity in explanation of the invention, the present invention will be described herein as used with a sin~le strip of suitable metallic band material, wherein the anchor bracket portion is integrally formed therefrom.
A typical brake band maybe formed in accordance with the processes tau~ht by United States Patent No. 5,381,876. Once the domed reaction bracket is formed, the peripheral surface area surrounding the reaction openin~ is ~enerally aligned in parallel with the curvilinear surface of the remainder of the band. The dome portion surrounding the reaction opening places the strap material into a 20 ~enerally perpendicular relationship with the reaction pin as it is inserted in the reaction opening. There is not a significant amount of rnaterial flow or working in forming on the hole, consequently the strength improving characteristic of the band material is usually not utilized at the locations where most stresses from hand operation are focused. Thus, 25 ~he present invention provides that the ed~e of the anchor hole be coined or work hardened to prestress the material and improve the material strength of the anchor bracket and thus, improve its fatigue life.
Typical brake bands of the type of the present invention are manufactured from SAE grade 980-XF material. One of the beneficial 30 characteristics of the SAE ~rade 980-XF metal is its work hardenin~
capability. Initially, the material is formable, but as the material is ~195514 formed, it ~ains stren~th in the formed areas. Therefore, the present invention provides for work hardenin~ or ~coinin~ of the perimeter ed~e surroundin~ the anchor hole to improve the material strength of the anchor hole and thus, improve its fati~ue life.
The inventii~n will be more readily understood after readin~ the followin~ best mode for carryin~ out the invention with reference to the accompanyin~ drawin~s.
BRIEF DESCRIPTION OF THE DRAWINGS
Fi~. 1 is an elevated side view of the transmission brake band of the present invention.
Fi~. 2 is a partial top plan view of the reaction bracket for the transmission brake band of Fi~. 1.
Fi~. 3 is a sectional view taken alon~ lines 3-3 of Fi~. 2.
Fi~. 4 is a partial top plan view of a first alternative embodiment of the reaction bracket of the transmission brake band of Fi~. 1.
Fi~. 5 is a sectional view taken alon~ lines 5-5 of Fi~. 4.
BEST MODF FOR CARRYING OUT THE INVFN~ION
Referrin~ now with particularity to the drawin~s, the present invention will be described in detail as a one-piece sin~le wrap brake band. However, it is not intended that this description of the invention in use with a sin~le wrap one-piece brake band be necessarily limitin~
upon the envisioned ran~e of the embodiments for the present invention.
Referrin~ now to Fi~. 1, a one-piece brake band ~enerally desi~nated by the reference No. 10 which is formed from an elon~ated strap of material 12 definin~ an annular band of determinant len~th. In the embodiment shown in Fi~. 1, the opposed ends 14, 16 of the strap 12 are folded over and rearwardly back upon the strap 12 to create bracket members 18, 20 desi~ned to en~aye an apply piston (not shown) and a reaction pin (not shown). The brake band further includes a ~1 955~ 4 friction linin~ (not shown~ suitably secured to the interior circumference 33 by an acceptable method of adhesion.
The apply bracket member 18 rnay be formed in any acceptable manner. The apply bracket member shown in Fi~. 1 is formed by foldin~
S the end 14 into an upwardly folded rid~e 26 havin~ a stren~thenin~ rib 28 on the side of the fold located below the contact point for an apply piston or pin. The folded rid~e 26 may or may not include a depressed area (not shown~ intended to form a pocket in the central area of the side opposite the stren~thenin~ rib 28. The depressed area is adapted to 10 enga~e the end of the apply piston actin~ in a ~enerally tangential direction to the clutch drum. The end 14 with rid~e 26 and stren~thenin~ rib 28 are folded over the strap 12 and secured to the strap, preferably in a simultaneous manufacturin~ step with the foldin~
and forming operation, by commonly accepted methods such as clinch 15 fastenin~ 30.
Referrin~ now to Fi~s. 2 and 3, the present invention resides in the end 16 which forrns the reaction bracket 20. The end 16 is formed by foldin~ the strap member 12 upwardly and rearwardly upon itself. The double layer of material is then subjected to an expansion and blankin~
20 operation which forms the dome 36 and creates the blanked hole or reaction openin~ 32. The surface area of the dome 36 surroundin~ the opening 32 is symrnetrically oriented to be substantially perpendicular to the axial center line formed by the reaction openin~ 32. Preferably, the blanked hole or reaction openin~ 32 includes four flats 34 such that the 25 reaction openin~ 32 is of a ~enerally square confi~uration. The flats 34 are ~enerally disposed in a 90~ relationship with one another and are joined with curved corners 38. Each of the flats 34 includes a work hardened or coined 40 area that extends the len~th of the flat 34. The work hardened area 40 is produced by compressin~ or coinin~ the strap 30 material proximate the flat 34, as shown in Fig. 3 by the arrow, to thereby reduce the cross-sectional thickness of the perimeter ed~e of 21 95~ 1 4 each flat 34. Work-hardenin~ or coinin~ thus stren~thens the strap material in the work hardened area 40. Preferably, the curvature of the coined or work hardened areas 40 matches the radial curvature of the corners 38 which act to join the flats 34 to~ether. The preferably width 5 of the coined area is .020 nches.
Referrin~ now to Fi~s. 4 and 5, an alternative embodiment of the present invention is disclosed. The alternative reaction bracket member 120 is formed by foldin~ the strap material 112 upwardly and rearwardly back upon itself. The double layer of strap material is subjected to an 10 expansion and piercin~ operation which forms a dome 136 and creates a blanked hole or reaction openin~ 132. The blanked hole or reaction openin~ 132 is circular in shape and the perimeter ed~e of the reaction openin~ 132 is work hardened or coined 140 about its entire circumference.
.
Exam~le A set of prototype bands built in accordance with the best mode of the present invention were compared with typical production bands made simultaneously from the same strip of steel and from the same 5 toolin~ set up so as to eliminate ;~ll variables other than the effects of work hardenin~ or coinin~. The fati~ue life of the bands, measured as the rnedian B10 life on the Weibul Distribution Fati~ue Analysis, built in accordance with the best mode of the present ;nvention and the typical production bands are shown in the followin~ table.
Table 1 Coined Bands Production Bands 73,900 54,200 68,900 44,000 56,900 33,900 55,300 30,700 47,500 30,000 1st Group 43,600 29,700 42,700 28,800 42,600 28,100 42,400 23,500 41,800 23,400 40,500 21,700 37,200 20,400 57,800 25,000 46,200 24,600 40,200 23,000 2nd Group 39,200 20,100 38,500 19,200 37,000 18,000 19,700 18,000 17,900 The data from the test ~roup shows an 80% increase in median B10 life by coinin~ or work-hardenin~ the anchor hole in accordance with the best mode of the present invention. For the coined bands, median B10 life was 28,424 cycles with a slope of 3.8. For the production bands, median B10 life was 15,787 ycles with a slope of 3.5. The slope measurement is indicative of the variability or distribution of results. The hi~her the slope number, the more narrow the band of variability or distribution and therefore, the more positive the results.
The work hardened and coined dome reaction bracket of the present invention provides for ~reater stren~th in retainin~ the reaction pin in position without premature failure of the brake band. It is intended that variations of the embodiments disclosed herein may be incorporated with reaction or apply brackets with transmission bands without the departin~ from the scope and content of the followin~ claims.
Claims (7)
1. A transmission brake band (10) for use in automatic transmissions, wherein an apply piston and a reaction member operatively engage the brake band with a clutch drum located within the automatic transmission comprising, in combination:
an elongated strap member (12) defining a generally annular interior circumference (33) and having an apply bracket (18) located at and integrally formed with one end (14) of said strap member (12) and a reaction bracket (20) located at and integrally formed with the opposed end (16) of said strap member (12); and a friction lining (24) adhered to the interior circumference (33) of the strap member (12);
whereby said reaction bracket (20) has a generally domed configuration (36) formed from said strap member (12) material to define a pocket in such annular interior circumference (33), said dome (36) having a reaction opening (32) extending therethrough to said pocket to define a longitudinal axis generally perpendicular to said domed configuration (36), said reaction opening (32) defining a perimeter edge, said perimeter edge being prestressed (40) about at least a portion of the perimeter edge of said reaction opening (32).
an elongated strap member (12) defining a generally annular interior circumference (33) and having an apply bracket (18) located at and integrally formed with one end (14) of said strap member (12) and a reaction bracket (20) located at and integrally formed with the opposed end (16) of said strap member (12); and a friction lining (24) adhered to the interior circumference (33) of the strap member (12);
whereby said reaction bracket (20) has a generally domed configuration (36) formed from said strap member (12) material to define a pocket in such annular interior circumference (33), said dome (36) having a reaction opening (32) extending therethrough to said pocket to define a longitudinal axis generally perpendicular to said domed configuration (36), said reaction opening (32) defining a perimeter edge, said perimeter edge being prestressed (40) about at least a portion of the perimeter edge of said reaction opening (32).
2. The brake band (10) of claim 1, wherein said reaction opening (32) is circular in shape and is prestressed (40) about its entire perimeter edge.
3. The brake band (10) of claim 2, wherein the perimeter edge of said reaction opening (32) is compressed and thereby reduced in cross-sectional thickness to effect such prestressed area (40).
4. The brake band (10) of claim 1, wherein said reaction opening (32) includes a perimeter edge configured from four flats (34) disposed in perpendicular relationship to each other.
5. The brake band (10) of claim 4, wherein the surface area of said dome (36) immediately adjacent each of said four flats (34) is prestressed (40).
6. The brake band (10) of claim 5, wherein each of said four flats (34) is mated to its adjacent flats (34) by a curved perimeter edge (38) of specified radius and said prestressed area (40) immediately adjacent each of said four flats (38) is of the same radial curvature as such curved perimeter edge (38).
7. The brake band (10) of claim 6, wherein each of said prestressed areas (40) is compressed and thereby reduced in cross-sectional thickness from the remainder of said dome (36).
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA002195514A CA2195514A1 (en) | 1997-01-20 | 1997-01-20 | Transmission band with anchor bracket having local coining at the anchor hole |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA002195514A CA2195514A1 (en) | 1997-01-20 | 1997-01-20 | Transmission band with anchor bracket having local coining at the anchor hole |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2195514A1 true CA2195514A1 (en) | 1998-07-20 |
Family
ID=4159698
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002195514A Abandoned CA2195514A1 (en) | 1997-01-20 | 1997-01-20 | Transmission band with anchor bracket having local coining at the anchor hole |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA2195514A1 (en) |
-
1997
- 1997-01-20 CA CA002195514A patent/CA2195514A1/en not_active Abandoned
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| FZDE | Discontinued |