CA2225395A1 - Tamper-resistant brake actuator - Google Patents
Tamper-resistant brake actuator Download PDFInfo
- Publication number
- CA2225395A1 CA2225395A1 CA002225395A CA2225395A CA2225395A1 CA 2225395 A1 CA2225395 A1 CA 2225395A1 CA 002225395 A CA002225395 A CA 002225395A CA 2225395 A CA2225395 A CA 2225395A CA 2225395 A1 CA2225395 A1 CA 2225395A1
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- CA
- Canada
- Prior art keywords
- flange
- head
- rim
- flange case
- case
- 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
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Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B60—VEHICLES IN GENERAL
- B60T—VEHICLE BRAKE CONTROL SYSTEMS OR PARTS THEREOF; BRAKE CONTROL SYSTEMS OR PARTS THEREOF, IN GENERAL; ARRANGEMENT OF BRAKING ELEMENTS ON VEHICLES IN GENERAL; PORTABLE DEVICES FOR PREVENTING UNWANTED MOVEMENT OF VEHICLES; VEHICLE MODIFICATIONS TO FACILITATE COOLING OF BRAKES
- B60T17/00—Component parts, details, or accessories of power brake systems not covered by groups B60T8/00, B60T13/00 or B60T15/00, or presenting other characteristic features
- B60T17/08—Brake cylinders other than ultimate actuators
- B60T17/083—Combination of service brake actuators with spring loaded brake actuators
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B60—VEHICLES IN GENERAL
- B60T—VEHICLE BRAKE CONTROL SYSTEMS OR PARTS THEREOF; BRAKE CONTROL SYSTEMS OR PARTS THEREOF, IN GENERAL; ARRANGEMENT OF BRAKING ELEMENTS ON VEHICLES IN GENERAL; PORTABLE DEVICES FOR PREVENTING UNWANTED MOVEMENT OF VEHICLES; VEHICLE MODIFICATIONS TO FACILITATE COOLING OF BRAKES
- B60T17/00—Component parts, details, or accessories of power brake systems not covered by groups B60T8/00, B60T13/00 or B60T15/00, or presenting other characteristic features
- B60T17/08—Brake cylinders other than ultimate actuators
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- Engineering & Computer Science (AREA)
- Transportation (AREA)
- Mechanical Engineering (AREA)
- Braking Systems And Boosters (AREA)
- Braking Arrangements (AREA)
Abstract
A fluid-operated combination diaphragm spring brake has a tamper-resistant connection between a head (36) and a flange case (34) which together form a spring chamber housing a power spring (52). The head has an annular flange (60) and an axial rim (62), and the flange case (34) has an annular flange (68) and an axial rim (70). The flanges of the head and the flange case and at least one of the rims of the head and the flange case define an annular recess (76). A diaphram (38) is sandwiched between the flanges and substantially fills the annular recess, removing substantially all the air within the annular recess. A welded connection (78) radially adjacent the diaphragm secures head rim to the flange case rim.
Description
TAMPER-RESISTANT BRAKE ACI'UATOR
BACKGROUND OF THE INVENTION
Field of the Invention This invention relates to diaphragm spring brake ~ctll~tors of the S type used with air brake systems on vehicles such as trucks. In one of itc aspects, the invention relates to a spring brake ~ctn~tQr having a tamper-e~:c~ spring chanber.
State of the Prior Art Spring brake ~ tors are in comm~n use with air brake systems 10 used on trucks, buses, and towed v~hicles. Such ~ctlJ~tors are typically provided with a service chamber for normally applying and rele~cing the brakes in res~ollse to delivery and c~ of co~ ,ressed air, and a spring chamber disposed in t~n~ieln with the service chamber for providing parking or emergency brake ftm~ tionC A spring brake ~ tor uses spring force to 15 operate a service brake ~ tor and apply brakes when l,les~ul~ed air in the spring chamber is reduced below some predetermined level. Air pre~u~e may be reduced in the spring chamber to apply the brakes under the control of the operator or automatically as a result of failure of the yles~ul~ed air system.
The service chamber and spring chamber are separated by an adapter or flange 20 casing which forms a wall between the two chambers.
In a typical spring brake ~ tor, a barrel-shaped power spring is used to store energy and to exert the large force required for braking in the event of air ~,res~ule failure. Air pressure acting on a diaphragm or a piston is employed to COlllpiCSS the spring and m~int~in it in its brake release position.25 When the air is eyh~llcte~l the spring acts on the diaphragm, typically an el~ctomeric diaphragm or a piston, and through an ~ ting rod exerts the spring force on the service push rod to apply the brakes in the event of a failure of the system air ~res~ule.
The spring brake ~ tor operates within the spring chamber, 30 which is typically formed by clamping an elastomeric diaphragm between a head (Sometim~s also known as a spring housing or spring chamber) ~nd the adapter.
The power spring is typically co~ lessed within the spring chamber between the head and the diaphragm. The spring has a high spring CO.I-CI~ and typically weighc 3 polln~C or more, being co,lli)r~ssed to a linear length of less than 3 5 inches from an original ~ ol~-~ssed length in an eYt~nde~i cnn~lition of from 9 to 12 inches. With a high spring co ~ , the spring has a s~lbst~nti~l ~mollnt of potential energy, exerting a force on the head of from 2,000 to 3,000 pounds.In previous diaphragm style brake ~ctu~tors, the brake ~ tor head is secured to the adapter by means of a band, generally U-shaped in cross 10 sectif n~ to clamp mating flanges on the head and adapter with the diaphragm cl~mped Lher~cl-.ecn. Typically the band is formed of sectionc bolted togethef for co-l~,ement flic~cce~nhly. ReC~lce the power spring is under great plcs~u,e,means must be provided to restrain or "cage" the power spring before the spring ,h~ ,,bcr can be safely dic~csçmhled. Failure to ~,lopclly cage the power spring15 prior to ~lic~ccernhly and the reslllti~ slldden release of potential energy in the spring can cause the head and adapter to fly apart.
To deter ~1ic~ccemhly of the spring charnber, the clamp band has been formed from a CQ.~ OUS ring, deformed over the flanges to form what is co~ llollly termed a sealed brake. Safety is an advantage of a sealed brake.
20 Rec~llce it must be defol~cd to be removed, a sealed brake clamp band or deformed nange deters dic~ce~ ly of the spring chamber.
The same feature which makes sealed brakes safer also deters future repair, bec~nce tlic~ccçm~ly iS ~liMclllt without ~m~ing the brake. If the diaphragm should fail for example, the entire brake actu~tQr may need to be 25 replaced. In any event, reCQn~litioni~ of a sealed brake is a very difficult procedure.
Other means are used for se~lnng the brake ~ tor head to the adapter in a tamper-lca;~ brake. For example, U.S. Patent No. 5,315,918 to Pierce, issued May 31, 1994, discloses a bayonet mount for securing the brake 30 actl~tQr head to the adapter. The brake ~ tor head and the adapter have complçmPnt~ry axially-eyten~lin~ lips. One of the }ips has a series of openings formed therein and in which is received a plug weld to secure the 9~l. tor head to the adapter.
U.S. Patent No. 5,285,716 to Thompson, issued February 15, 1994, dic~AlQsec the welding of a brake ~ct~ tor head to an adapter in such a manner S so that the weld securing the brake ~ Ator head to the adapter is a sl~ffiripnt ~lict~n-~e from the diaphragm so as not to burn the diaphragm. Spe- ifiA~lly, the brake nctl~AtQr head has an aYially-eYt~Pn~ing flange that ovell~s an aYially-eYtPnding flange of the adapter and eYtP-n~s a suffilcient flict~nce from the diaphragm co~ ,rcsscd between the act~<ltQr bead and the adapter so that the 10 heat from the weld formed at the end of the aYially-eYtending flange of the Ac~l9tor head will not burn the diaphragm.
SUMMARY OF THE rNVENTlON
Accor.l~lg to the invention, a fluid-operated brake ~ctll~Ator of the type which has a generally cylindrical head and a flange case with an el~ctomeric diaphragm between the two has a welded connection ~ dj~cent to the peripheral portion of the diaphragm. The flange case and the head have radially eyten(ling flanges which are shaped to co~ ress the peripheral edge of the diaphragm so that the diaphragm s~lbst~nti~lly fills an ~nnlll~r recess formed between radially eYtendin~ flanges on the flange case and the ~ylindrical head.
In one embo~liment~ the head and the flange case both have aY~ially eytenrling rims on the outer edges of the fl~ngec The rims overlap and the weld is made between the rims.
Rec~llce the el~ctomeric gasket s~lbst~nti~lly completely fills the ~nnl~l~r spaces formed between the radially eYtending _anges between the head and the flange case and closed by ~nmll~r rims on the flanges, the welds can be placed radially ~dj~ce-nt to the el~ctomeric diaphragm without deleteriously burning the diaphragm. Thus, the seal rel,la",s intact between the head and the flange case. Yet, the connection can be welded to avoid lm~l-thQrized tampering. Thus, material cQ.~te~L can be decreased, there~y decreasing the cost and weight of the spAng brake ~ct~-~tor.
CA 02225395 l998-0l-30 W O 97/06041 PCTrUS95110074 BRIEF DESCRIPIlON OF THE DRAWINGS
The invention will now be described with reference to the ;I~comr~nying d-awi,l~ in which:
FIG. 1 shows an elevational view of a fluid-operated combination 5 diaphragm spring brake ~ tor accordillg to the invention; and FIG. 2 is a partial sectiQn~l view of the fluid-operated comhin~tion diaphragm spring brake ~ tor of FIG. 1.
DETAILED DESCRIPI~ON OF THE DRAWINGS
Refe.,mg now to FIGS. 1 and 2, there is shown a fluid-operated 10 brake ~ tor 10 in accordance with the invention. The particular embo~limPnt shown is a fluid-operated co...l. n~t;on diaphragm spring brake actll~tQr havingboth a service chamber 12 and a spring chamber 14. The brake ~ch1~tor is adapted to mount to a mollntine bracket (not shown) of a vehicle aYle and is further adapted to operate a brake (not shown) through a service push rod 16 15 which ~ c~lly PYtP~iS to and cQnn~Pcts with a slack adjuster and the braking system of t_e vehicle.
Altho.leh the invention relates to a spring chamber, the service chamber 12 and spring chamber 14 are illustrated joined together in t~n~em bec~llse this atla~gelllent is CO.~ in a spring brake ~ tor. The co,~luction of the service chamber 12 iS well known. Therefore, the service chamber 12 will only be described generally. The service chanuber 12 iS ~efine~
by a cup-shaped lower serYice housing 18 and a cup-shaped upper service hollcine 20 joined together by a clarnp 22 to form a hollow interior chamber. A
first el~c(o...~ric diapLr~lll24 (also known as the service brake diaphragm) is co~ ressed in fluid-tight en~ n ent between the lower service housing 18 and the upper service housing 20. A service chamber air port 26iS connected to a source of ples~ure to pre~ul~e the upper service housing 20 and to an eYh~llst valve (not shown) to reciprocally ~ctu~te the service push rod 16 upon the additi~n and eYh~uctiQn of air.
The spring chamber 14 is defined by a flange case 34 and a generally cylindrical head 36, also known as a spring chamber, which is secured to the flange case 34. It is the securing of the chamber 36 to the flange case 34 that is the ,pro.~lllent which forms the subject matter of the invention as willbe shown. A second elastomeric diaphragm 38, known as the spring diaphragr4 is clamped in fluid-tight engagement between the flange case 34 and the 5 ch~,-ber 36 to form a pres~ule chamber 46 between the spring diaphragm 38 and flange case 34.
A spring air port 40 ~Yt~ntlc from the flange case to c~mnect the pre~urc chamber 46 with a source of prec!~ur;i-ed air (not shown). ~essul-2ed air is directed into the pressure chamber 46 between the diaphragm 38 and the 10 flange c~e 34.
A spring push rod 42 eytentls through the flange case 34 and upper service housing 20 through a seal 44 so that one end of the spring push rod 42 is within the spring ~l.~ber 14 and the other end is within the service er 12. The spring push rod 42 has a re~is)n plate 48 rigidly molmte~l to 15 the end in the service ch~ber 12, and a l,ies~ure plate 50 is mollnted to theother end in the spring chamber 14. The ~rcs~ure plate S0 bears against the diaphragrn 38. A power spring 52 is position~d between the pres~ule plate 50 and the head 36 to bias the l~res~ule plate 50 and the spring push rod 42 against the force of the ~resslll~cd air in the pres~ule chamber 46. When pressurized 20 air is forced into the pre;,~ure cl.~ber 46, it o.ercollles the force of the power spring 52 to retract the spring push rod 42 and release the brake. When the ples~ul~ed air is eYh~llsteA, the power spring 52 moves the spring push rod 42 to ~ctu~te the bralce.
As illustrated, the service chamber 12 is mounted to the spring chamber 14 by welding the upper service hollcin~e 20 to the flange case 34.
However, it is co~ on for the upper service housing 20 and flange case 34 to be made as a single piece, which is often referred to as an adapter honcine~ It ~ is within the scope of the invention for the fluid-operated brake ~C~u~t5~r 10 to incolllor~te a one-piece adapter housing.
A release tool 56 can be provided within a central opening 61 of the head 36 for m~ch~nically drawing the ~re~sure plate 50 into a retracted or "caged" position in the event there is a need to mech~nically release the brake.
The release tool typically CO~ , ses a threaded rod having an integral head on the bottom end thereof and a nut swaged on the top thereof. A second nut is threaded onto the rod and is welded to the head 36. The head on the nut is selectively engageable with portions of the pressure plate 50 in a m~nner well S known in the spring brake ac~latQr field to retract the pres~ule plate as the rod is u~ eaded from the head.
T ~okine now more closely at the connection securing the flange case 34 to the cylindrical head 36, the cylindrical head hac a ch~u~erential, radially eyten~line flange 60 from which PYten~lc a circumferential aY~ial flange 10 62. Preferably, the radial flange 60 has a slight upw~rd cant in a radial direction or, in other words, forms an ulJ..aldly rYten~ling acute angle with resl,c~;l to a plane that is orthogonal to the lone tu~lin~l axis of the spring push rod. The a~Yial aange 62 eYt~n~ls axially toward the service chamber 12 and is snb~l;~..l;~lly parallel to the loneit.~l~lin~l axis of the spring push rod. ~lefe~ably, the radial 15 aange 60 and axial aange 62 are formed by s~,~hlg the head 36. A radius tr~nCitinln at 64 is formed between the side wall 63 of the head 36 and radial f~ange 60 and a radius tr~n.cition at 66 is formed between radial flange 60 and axial flange 62.
In a similar m~nnP.r, the flange cace 34 also has a .h~ elenlial, 20 radially-PYten~ine flange 68 from which eYtçn~lc a circ-l~elc~lial axial flange 70, which te~...in~tes in a terminal edge 71. Preferably, the radial flange 68 formc a dowl-wardly eYten~line acute angle with respect to a plane orthogonal tothe loneit~l~lin~l axis of the spring push rod 42. The radial flange 68 and aYial flange 70 are also created by bçn-line the flange case 34, forming sholllders 7225 and 74. The radial flange 68 eyte~tlc a radial (lict~n~e less than the radialflange 60 of the head 36. The di~ere~ce in the radial extension of the two radial flanges 68, 60 is a~ o~;...~tely e~ual to the thir~ne$s of the axial flange 62 to permit the axial flange 70 to nest within the axial flange 62.
During ~ccembly of the brake ~ct~tor 10, the spring diaphragm 38 30 has an ~nnnl~r bead which is disposed between the radial flanges 60 and 68 and co~ cssed therebetween, preferably by applying a co~l~prcssive force between the radial flanges 60 and 68. An ~nnlll~r recess 76 is formed by the radial flanges 60, 68 and axial flanges 62, 70. The bead on the spring diaphragm 38 has a shape ~ro~ A~ g the ~nn~ r recess 76. The radial flanges 60 and 68 are in ~ligrment and col~ress the spring diaphragm therebetween to assure ecc~-nti~lly complete filling of the bead of the spring diaphragm 38 into the S ~nn~ r recess. As the spring diaphragm 38 is col-lplessed between the radial flanges 60 and 68, a portion of the spring diaphragm 38 is directed into and completely fills the ~nmll~r recess. The axial flange 70 can be of a predetermined length so that the terminal edge 71 of the axial flange 70 abuts the radial flange 60 when the spring diaphragm 38 is fully colllpressed. The 10 axial flange 62 is welded to the axial flange 70 along weld 78. The weld 78 is ~,re~elably a weld wherein the axial flange 62 is fused to the axial flange 70 without the addition of weld material and ,~in~ es the heat affected zone.
~d~ition~lly~ with specific procesces, a heat sink may be nece~ to remove excess heat.
.Although the spring diaphragm 38 may be singed by the heat, the s~mg is not sllffir~ent to degrade the pelrollllance of the spring diaphragm as would occur if the spring diaphragm were bumt during the welding process.
By placing the weld adjacent to the diaphragm, less material is required to m~nl~f~cture the head 36 and flange case 34. It is not llcce~c~. ~r to 20 extend the edge of the axial flange beyond the diaphragm to pl~ell~ the heat from the weld at the edge of the flange from burl~ the diaphragm, as in previous brake a~ Atol~.
In operation, air ~,res~ure is co..~ lly supplied to the spring chamber 14 through the spring air port 40 to m~int~in the spring diaphragm 38 25 in a position to colllpless the power spring 52. In this positionJ the service push rod 16 normally will be operated, as described above, by selective pres~uli~dlion of air into the service chamber 12 through the service air port 26. However, in the event of a loss of prc~ure, either intçnti(!n~lly, as when the ~arkillg brake is set, or by failure of the air pres~urc systern, the ~,rcss~lre in the spring chamber 30 14 will be decreased and the power spring 52 will activate the brakes by pushing the plCSSule plate 50, spring diaphragm 38, and thus the spring push rod 42 to thereby ~ tç the sennce push rod 16 to apply braking pres~ e to the brakes.
Re~con~le variation and modification are possible within the scope of the foregoing ~~ic~losl-re without dep~lhlg from the spirit of the invention which is clefined in the ~cco~ y,ng claim_.
BACKGROUND OF THE INVENTION
Field of the Invention This invention relates to diaphragm spring brake ~ctll~tors of the S type used with air brake systems on vehicles such as trucks. In one of itc aspects, the invention relates to a spring brake ~ctn~tQr having a tamper-e~:c~ spring chanber.
State of the Prior Art Spring brake ~ tors are in comm~n use with air brake systems 10 used on trucks, buses, and towed v~hicles. Such ~ctlJ~tors are typically provided with a service chamber for normally applying and rele~cing the brakes in res~ollse to delivery and c~ of co~ ,ressed air, and a spring chamber disposed in t~n~ieln with the service chamber for providing parking or emergency brake ftm~ tionC A spring brake ~ tor uses spring force to 15 operate a service brake ~ tor and apply brakes when l,les~ul~ed air in the spring chamber is reduced below some predetermined level. Air pre~u~e may be reduced in the spring chamber to apply the brakes under the control of the operator or automatically as a result of failure of the yles~ul~ed air system.
The service chamber and spring chamber are separated by an adapter or flange 20 casing which forms a wall between the two chambers.
In a typical spring brake ~ tor, a barrel-shaped power spring is used to store energy and to exert the large force required for braking in the event of air ~,res~ule failure. Air pressure acting on a diaphragm or a piston is employed to COlllpiCSS the spring and m~int~in it in its brake release position.25 When the air is eyh~llcte~l the spring acts on the diaphragm, typically an el~ctomeric diaphragm or a piston, and through an ~ ting rod exerts the spring force on the service push rod to apply the brakes in the event of a failure of the system air ~res~ule.
The spring brake ~ tor operates within the spring chamber, 30 which is typically formed by clamping an elastomeric diaphragm between a head (Sometim~s also known as a spring housing or spring chamber) ~nd the adapter.
The power spring is typically co~ lessed within the spring chamber between the head and the diaphragm. The spring has a high spring CO.I-CI~ and typically weighc 3 polln~C or more, being co,lli)r~ssed to a linear length of less than 3 5 inches from an original ~ ol~-~ssed length in an eYt~nde~i cnn~lition of from 9 to 12 inches. With a high spring co ~ , the spring has a s~lbst~nti~l ~mollnt of potential energy, exerting a force on the head of from 2,000 to 3,000 pounds.In previous diaphragm style brake ~ctu~tors, the brake ~ tor head is secured to the adapter by means of a band, generally U-shaped in cross 10 sectif n~ to clamp mating flanges on the head and adapter with the diaphragm cl~mped Lher~cl-.ecn. Typically the band is formed of sectionc bolted togethef for co-l~,ement flic~cce~nhly. ReC~lce the power spring is under great plcs~u,e,means must be provided to restrain or "cage" the power spring before the spring ,h~ ,,bcr can be safely dic~csçmhled. Failure to ~,lopclly cage the power spring15 prior to ~lic~ccernhly and the reslllti~ slldden release of potential energy in the spring can cause the head and adapter to fly apart.
To deter ~1ic~ccemhly of the spring charnber, the clamp band has been formed from a CQ.~ OUS ring, deformed over the flanges to form what is co~ llollly termed a sealed brake. Safety is an advantage of a sealed brake.
20 Rec~llce it must be defol~cd to be removed, a sealed brake clamp band or deformed nange deters dic~ce~ ly of the spring chamber.
The same feature which makes sealed brakes safer also deters future repair, bec~nce tlic~ccçm~ly iS ~liMclllt without ~m~ing the brake. If the diaphragm should fail for example, the entire brake actu~tQr may need to be 25 replaced. In any event, reCQn~litioni~ of a sealed brake is a very difficult procedure.
Other means are used for se~lnng the brake ~ tor head to the adapter in a tamper-lca;~ brake. For example, U.S. Patent No. 5,315,918 to Pierce, issued May 31, 1994, discloses a bayonet mount for securing the brake 30 actl~tQr head to the adapter. The brake ~ tor head and the adapter have complçmPnt~ry axially-eyten~lin~ lips. One of the }ips has a series of openings formed therein and in which is received a plug weld to secure the 9~l. tor head to the adapter.
U.S. Patent No. 5,285,716 to Thompson, issued February 15, 1994, dic~AlQsec the welding of a brake ~ct~ tor head to an adapter in such a manner S so that the weld securing the brake ~ Ator head to the adapter is a sl~ffiripnt ~lict~n-~e from the diaphragm so as not to burn the diaphragm. Spe- ifiA~lly, the brake nctl~AtQr head has an aYially-eYt~Pn~ing flange that ovell~s an aYially-eYtPnding flange of the adapter and eYtP-n~s a suffilcient flict~nce from the diaphragm co~ ,rcsscd between the act~<ltQr bead and the adapter so that the 10 heat from the weld formed at the end of the aYially-eYtending flange of the Ac~l9tor head will not burn the diaphragm.
SUMMARY OF THE rNVENTlON
Accor.l~lg to the invention, a fluid-operated brake ~ctll~Ator of the type which has a generally cylindrical head and a flange case with an el~ctomeric diaphragm between the two has a welded connection ~ dj~cent to the peripheral portion of the diaphragm. The flange case and the head have radially eyten(ling flanges which are shaped to co~ ress the peripheral edge of the diaphragm so that the diaphragm s~lbst~nti~lly fills an ~nnlll~r recess formed between radially eYtendin~ flanges on the flange case and the ~ylindrical head.
In one embo~liment~ the head and the flange case both have aY~ially eytenrling rims on the outer edges of the fl~ngec The rims overlap and the weld is made between the rims.
Rec~llce the el~ctomeric gasket s~lbst~nti~lly completely fills the ~nnl~l~r spaces formed between the radially eYtending _anges between the head and the flange case and closed by ~nmll~r rims on the flanges, the welds can be placed radially ~dj~ce-nt to the el~ctomeric diaphragm without deleteriously burning the diaphragm. Thus, the seal rel,la",s intact between the head and the flange case. Yet, the connection can be welded to avoid lm~l-thQrized tampering. Thus, material cQ.~te~L can be decreased, there~y decreasing the cost and weight of the spAng brake ~ct~-~tor.
CA 02225395 l998-0l-30 W O 97/06041 PCTrUS95110074 BRIEF DESCRIPIlON OF THE DRAWINGS
The invention will now be described with reference to the ;I~comr~nying d-awi,l~ in which:
FIG. 1 shows an elevational view of a fluid-operated combination 5 diaphragm spring brake ~ tor accordillg to the invention; and FIG. 2 is a partial sectiQn~l view of the fluid-operated comhin~tion diaphragm spring brake ~ tor of FIG. 1.
DETAILED DESCRIPI~ON OF THE DRAWINGS
Refe.,mg now to FIGS. 1 and 2, there is shown a fluid-operated 10 brake ~ tor 10 in accordance with the invention. The particular embo~limPnt shown is a fluid-operated co...l. n~t;on diaphragm spring brake actll~tQr havingboth a service chamber 12 and a spring chamber 14. The brake ~ch1~tor is adapted to mount to a mollntine bracket (not shown) of a vehicle aYle and is further adapted to operate a brake (not shown) through a service push rod 16 15 which ~ c~lly PYtP~iS to and cQnn~Pcts with a slack adjuster and the braking system of t_e vehicle.
Altho.leh the invention relates to a spring chamber, the service chamber 12 and spring chamber 14 are illustrated joined together in t~n~em bec~llse this atla~gelllent is CO.~ in a spring brake ~ tor. The co,~luction of the service chamber 12 iS well known. Therefore, the service chamber 12 will only be described generally. The service chanuber 12 iS ~efine~
by a cup-shaped lower serYice housing 18 and a cup-shaped upper service hollcine 20 joined together by a clarnp 22 to form a hollow interior chamber. A
first el~c(o...~ric diapLr~lll24 (also known as the service brake diaphragm) is co~ ressed in fluid-tight en~ n ent between the lower service housing 18 and the upper service housing 20. A service chamber air port 26iS connected to a source of ples~ure to pre~ul~e the upper service housing 20 and to an eYh~llst valve (not shown) to reciprocally ~ctu~te the service push rod 16 upon the additi~n and eYh~uctiQn of air.
The spring chamber 14 is defined by a flange case 34 and a generally cylindrical head 36, also known as a spring chamber, which is secured to the flange case 34. It is the securing of the chamber 36 to the flange case 34 that is the ,pro.~lllent which forms the subject matter of the invention as willbe shown. A second elastomeric diaphragm 38, known as the spring diaphragr4 is clamped in fluid-tight engagement between the flange case 34 and the 5 ch~,-ber 36 to form a pres~ule chamber 46 between the spring diaphragm 38 and flange case 34.
A spring air port 40 ~Yt~ntlc from the flange case to c~mnect the pre~urc chamber 46 with a source of prec!~ur;i-ed air (not shown). ~essul-2ed air is directed into the pressure chamber 46 between the diaphragm 38 and the 10 flange c~e 34.
A spring push rod 42 eytentls through the flange case 34 and upper service housing 20 through a seal 44 so that one end of the spring push rod 42 is within the spring ~l.~ber 14 and the other end is within the service er 12. The spring push rod 42 has a re~is)n plate 48 rigidly molmte~l to 15 the end in the service ch~ber 12, and a l,ies~ure plate 50 is mollnted to theother end in the spring chamber 14. The ~rcs~ure plate S0 bears against the diaphragrn 38. A power spring 52 is position~d between the pres~ule plate 50 and the head 36 to bias the l~res~ule plate 50 and the spring push rod 42 against the force of the ~resslll~cd air in the pres~ule chamber 46. When pressurized 20 air is forced into the pre;,~ure cl.~ber 46, it o.ercollles the force of the power spring 52 to retract the spring push rod 42 and release the brake. When the ples~ul~ed air is eYh~llsteA, the power spring 52 moves the spring push rod 42 to ~ctu~te the bralce.
As illustrated, the service chamber 12 is mounted to the spring chamber 14 by welding the upper service hollcin~e 20 to the flange case 34.
However, it is co~ on for the upper service housing 20 and flange case 34 to be made as a single piece, which is often referred to as an adapter honcine~ It ~ is within the scope of the invention for the fluid-operated brake ~C~u~t5~r 10 to incolllor~te a one-piece adapter housing.
A release tool 56 can be provided within a central opening 61 of the head 36 for m~ch~nically drawing the ~re~sure plate 50 into a retracted or "caged" position in the event there is a need to mech~nically release the brake.
The release tool typically CO~ , ses a threaded rod having an integral head on the bottom end thereof and a nut swaged on the top thereof. A second nut is threaded onto the rod and is welded to the head 36. The head on the nut is selectively engageable with portions of the pressure plate 50 in a m~nner well S known in the spring brake ac~latQr field to retract the pres~ule plate as the rod is u~ eaded from the head.
T ~okine now more closely at the connection securing the flange case 34 to the cylindrical head 36, the cylindrical head hac a ch~u~erential, radially eyten~line flange 60 from which PYten~lc a circumferential aY~ial flange 10 62. Preferably, the radial flange 60 has a slight upw~rd cant in a radial direction or, in other words, forms an ulJ..aldly rYten~ling acute angle with resl,c~;l to a plane that is orthogonal to the lone tu~lin~l axis of the spring push rod. The a~Yial aange 62 eYt~n~ls axially toward the service chamber 12 and is snb~l;~..l;~lly parallel to the loneit.~l~lin~l axis of the spring push rod. ~lefe~ably, the radial 15 aange 60 and axial aange 62 are formed by s~,~hlg the head 36. A radius tr~nCitinln at 64 is formed between the side wall 63 of the head 36 and radial f~ange 60 and a radius tr~n.cition at 66 is formed between radial flange 60 and axial flange 62.
In a similar m~nnP.r, the flange cace 34 also has a .h~ elenlial, 20 radially-PYten~ine flange 68 from which eYtçn~lc a circ-l~elc~lial axial flange 70, which te~...in~tes in a terminal edge 71. Preferably, the radial flange 68 formc a dowl-wardly eYten~line acute angle with respect to a plane orthogonal tothe loneit~l~lin~l axis of the spring push rod 42. The radial flange 68 and aYial flange 70 are also created by bçn-line the flange case 34, forming sholllders 7225 and 74. The radial flange 68 eyte~tlc a radial (lict~n~e less than the radialflange 60 of the head 36. The di~ere~ce in the radial extension of the two radial flanges 68, 60 is a~ o~;...~tely e~ual to the thir~ne$s of the axial flange 62 to permit the axial flange 70 to nest within the axial flange 62.
During ~ccembly of the brake ~ct~tor 10, the spring diaphragm 38 30 has an ~nnnl~r bead which is disposed between the radial flanges 60 and 68 and co~ cssed therebetween, preferably by applying a co~l~prcssive force between the radial flanges 60 and 68. An ~nnlll~r recess 76 is formed by the radial flanges 60, 68 and axial flanges 62, 70. The bead on the spring diaphragm 38 has a shape ~ro~ A~ g the ~nn~ r recess 76. The radial flanges 60 and 68 are in ~ligrment and col~ress the spring diaphragm therebetween to assure ecc~-nti~lly complete filling of the bead of the spring diaphragm 38 into the S ~nn~ r recess. As the spring diaphragm 38 is col-lplessed between the radial flanges 60 and 68, a portion of the spring diaphragm 38 is directed into and completely fills the ~nmll~r recess. The axial flange 70 can be of a predetermined length so that the terminal edge 71 of the axial flange 70 abuts the radial flange 60 when the spring diaphragm 38 is fully colllpressed. The 10 axial flange 62 is welded to the axial flange 70 along weld 78. The weld 78 is ~,re~elably a weld wherein the axial flange 62 is fused to the axial flange 70 without the addition of weld material and ,~in~ es the heat affected zone.
~d~ition~lly~ with specific procesces, a heat sink may be nece~ to remove excess heat.
.Although the spring diaphragm 38 may be singed by the heat, the s~mg is not sllffir~ent to degrade the pelrollllance of the spring diaphragm as would occur if the spring diaphragm were bumt during the welding process.
By placing the weld adjacent to the diaphragm, less material is required to m~nl~f~cture the head 36 and flange case 34. It is not llcce~c~. ~r to 20 extend the edge of the axial flange beyond the diaphragm to pl~ell~ the heat from the weld at the edge of the flange from burl~ the diaphragm, as in previous brake a~ Atol~.
In operation, air ~,res~ure is co..~ lly supplied to the spring chamber 14 through the spring air port 40 to m~int~in the spring diaphragm 38 25 in a position to colllpless the power spring 52. In this positionJ the service push rod 16 normally will be operated, as described above, by selective pres~uli~dlion of air into the service chamber 12 through the service air port 26. However, in the event of a loss of prc~ure, either intçnti(!n~lly, as when the ~arkillg brake is set, or by failure of the air pres~urc systern, the ~,rcss~lre in the spring chamber 30 14 will be decreased and the power spring 52 will activate the brakes by pushing the plCSSule plate 50, spring diaphragm 38, and thus the spring push rod 42 to thereby ~ tç the sennce push rod 16 to apply braking pres~ e to the brakes.
Re~con~le variation and modification are possible within the scope of the foregoing ~~ic~losl-re without dep~lhlg from the spirit of the invention which is clefined in the ~cco~ y,ng claim_.
Claims (10)
1. In a fluid-operated brake actuator comprising:
a generally cylindrical head having at one end a radially extending flange and a circumferential rim extending from the head flange;
a flange case having at one end a radially extending flange and a circumferential rim extending axially from the flange case radial flange, the flange case circumferential rim being in abutting relationship with the head circumferential rim and welded thereto;
an annular recess defined by the head radially extending flange, flange case radially extending flange, and at least one of the head rim and flange case rim; and an elastomeric diaphragm having a circumferential peripheral edge held in compression between the head flange and the flange case flange by the welded connection; the improvement which comprises:
the weld between the flange case circumferential rim and the head circumferential rim is radially adjacent the edge of the elastomeric diaphragm and the elastomeric diaphragm substantially fills the annular recess, whereby burning of the elastomeric diaphragm during welding of the circumferential rim of the flange case to the circumferential rim of the head is minimized.
a generally cylindrical head having at one end a radially extending flange and a circumferential rim extending from the head flange;
a flange case having at one end a radially extending flange and a circumferential rim extending axially from the flange case radial flange, the flange case circumferential rim being in abutting relationship with the head circumferential rim and welded thereto;
an annular recess defined by the head radially extending flange, flange case radially extending flange, and at least one of the head rim and flange case rim; and an elastomeric diaphragm having a circumferential peripheral edge held in compression between the head flange and the flange case flange by the welded connection; the improvement which comprises:
the weld between the flange case circumferential rim and the head circumferential rim is radially adjacent the edge of the elastomeric diaphragm and the elastomeric diaphragm substantially fills the annular recess, whereby burning of the elastomeric diaphragm during welding of the circumferential rim of the flange case to the circumferential rim of the head is minimized.
2. A fluid-operated brake actuator according to claim 1 wherein the head and flange case rims are in overlapping relationship.
3. A fluid-operated brake actuator according to claim 2 wherein at least the rim of one of the head and flange case terminates in an edge, and the edge terminates at a point adjacent the flange of the other of thehead and the flange case.
4. A fluid-operated brake actuator according to claim 3 wherein the annular recess is defined by the flanges of the head and the flange case and the rim of the one of the head and flange case.
5. A fluid-operated brake actuator according to claim 1 wherein the diameter of the rim of the one of the head and the flange case is less than the diameter of the rim of the other of the head and the flange case whereby the rims of one of the head and flange case can be nested within the rim of the other of the head and the flange case in overlapping relationship.
6. A fluid-operated brake actuator according to claim 5 wherein at least the rim of one of the head and flange case terminates in an edge, and the edge terminates at a point adjacent the flange of the of the otherof the head and the flange case.
7. A fluid-operated brake actuator according to claim 6 wherein the annular recess is defined by the flanges of the head and the flange case and the rim of the one of the head and flange case.
8. A fluid-operated brake actuator according to claim 1 wherein the welded connection is a spot weld.
9. A fluid-operated brake actuator according to claim 1 wherein the weld extends around at least a portion of the circumference of the brake actuator.
10. In a fluid-operated brake actuator comprising.
a generally cylindrical head having at one end a radially extending flange;
a flange case having at one end a radially extending flange;
an elastomeric diaphragm positioned between the radially extending flanges of the head and the flange case and compressed into an annular recess defined in part by the radially extending flanges of the head andthe flange case; and an annular closure member closing the annular recess formed by the radially extending flanges of the head and the flange case, the improvement which comprises:
a circumferential portion of the elastomeric diaphragm substantially completely fills the annular recess and a weld is provided in the circumferential member to secure the radially extending flanges in tight clampedrelationship whereby the head is secured to the flange case, the weld being positioned radially outwardly of the annular recess and adjacent to at least a portion of the circumferential portion of the elastomeric diaphragm.
a generally cylindrical head having at one end a radially extending flange;
a flange case having at one end a radially extending flange;
an elastomeric diaphragm positioned between the radially extending flanges of the head and the flange case and compressed into an annular recess defined in part by the radially extending flanges of the head andthe flange case; and an annular closure member closing the annular recess formed by the radially extending flanges of the head and the flange case, the improvement which comprises:
a circumferential portion of the elastomeric diaphragm substantially completely fills the annular recess and a weld is provided in the circumferential member to secure the radially extending flanges in tight clampedrelationship whereby the head is secured to the flange case, the weld being positioned radially outwardly of the annular recess and adjacent to at least a portion of the circumferential portion of the elastomeric diaphragm.
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| PCT/US1995/010074 WO1997006041A1 (en) | 1995-08-09 | 1995-08-09 | Tamper-resistant brake actuator |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2225395A1 true CA2225395A1 (en) | 1997-02-20 |
Family
ID=25679946
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002225395A Abandoned CA2225395A1 (en) | 1995-08-09 | 1995-08-09 | Tamper-resistant brake actuator |
Country Status (6)
| Country | Link |
|---|---|
| EP (1) | EP0843631A1 (en) |
| JP (1) | JPH11510760A (en) |
| KR (1) | KR100347233B1 (en) |
| AU (1) | AU3278395A (en) |
| CA (1) | CA2225395A1 (en) |
| WO (1) | WO1997006041A1 (en) |
Families Citing this family (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2004083004A1 (en) | 2003-03-21 | 2004-09-30 | Siemens Aktiengesellschaft | System and method for identifying seat occupancy in a vehicle |
| US7202494B2 (en) | 2003-06-26 | 2007-04-10 | Rj Mears, Llc | FINFET including a superlattice |
| US9073527B2 (en) * | 2011-03-31 | 2015-07-07 | Haldex Brake Corporation | Smooth bore dynamic center seal for spring brake actuator |
| KR101428920B1 (en) * | 2013-04-10 | 2014-08-08 | (주)지앤피오토모티브 | brake actuator |
Family Cites Families (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3994206A (en) * | 1973-10-25 | 1976-11-30 | Svenska Aktiebolaget Bromsregulator | Device for discontinuing and automatically restoring the operational function of a spring brake actuator |
| US4960036A (en) * | 1987-11-06 | 1990-10-02 | Indian Head Industries, Inc. | Tamper-resistant brake actuator |
| AU5547194A (en) * | 1993-11-01 | 1995-05-23 | Tse Brakes, Inc. | Brake actuator having tamper-resistant housing and method for making same |
-
1995
- 1995-08-09 WO PCT/US1995/010074 patent/WO1997006041A1/en active IP Right Grant
- 1995-08-09 KR KR1019980700918A patent/KR100347233B1/en not_active IP Right Cessation
- 1995-08-09 JP JP9508397A patent/JPH11510760A/en not_active Ceased
- 1995-08-09 EP EP95929423A patent/EP0843631A1/en not_active Withdrawn
- 1995-08-09 AU AU32783/95A patent/AU3278395A/en not_active Abandoned
- 1995-08-09 CA CA002225395A patent/CA2225395A1/en not_active Abandoned
Also Published As
| Publication number | Publication date |
|---|---|
| EP0843631A1 (en) | 1998-05-27 |
| JPH11510760A (en) | 1999-09-21 |
| WO1997006041A1 (en) | 1997-02-20 |
| KR19990036250A (en) | 1999-05-25 |
| AU3278395A (en) | 1997-03-05 |
| KR100347233B1 (en) | 2002-11-25 |
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Legal Events
| Date | Code | Title | Description |
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| FZDE | Dead |