US 3401437 A
Abstract available in
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Description (OCR text may contain errors)
SePt- 17,1968 C. E. CHRISTOPHERSEN 3,401,437
' HosE CLAMP Filed May 10, 1967 2 Sheets-Sheet l /2 35 40 l 4a 33 T166 INVENTOR CLARE NC E E. CHRISTOPHERSEN ATTORNEY Sept. 17, 1968 QE. cHmsToPHERsz-:N i 3,401,437
-' HOSE CLAMPr I .filed May 1o, 1967 2 Smeets-snee*b '2 d a N INVENTOR CLARENCE E. CHRlSTOPHERSEN Xu' ATTORNEY United States Patent O 3,401,437 HOSE CLAMP Clarence E. Christophersen, Los Angeles, Calif., assignor to Aeroquip Corporation, `lackson, Mich. Filed May 10, 1967, Ser. No. 637,559 5 Claims. (Cl. 24-274) ABSTRACT 0F THE DISCLOSURE A clamp of the circumferential type, such as commonly used with hose and exible pipe, consisting of a exible band having teeth formed therein, and scroll drive means mounted upon the band in engagement with the teeth to provide circumferential adjustment of the clamp.
Field olf the invention The invention pertains to the field of circumferential clamps utilizing scroll or spiral drive means for adjusting the circumference of the band. In the device of the invention a flexible band or strap having teeth formed thereon includes a scroll type cam mounted adjacent one end of the band which engages teeth defined adjacent the other end of the band. The end of the band in engagement with the scroll passes between the scroll and the other band end wherein the band is maintained and adjusted in an annular configuration.
Scroll drive circumferential clamps of the type previously known are shown in United States Patents 2,907,086, 3,035,319 and 3,276,090. Devices of the type disclosed in these patents have not enjoyed significant commercial success in that the construction of these patented clamps did not overcome several of the problems attendant with this type of clamp. For instance the scroll and band teeth engagement must be such that the forces transmitted between these components do not tend to separate the scroll and teeth, as is the case in clamps shown in Patents 3,035,319 and 3,276,090. Also with this type of clamp significant frictional forces are created between the band teeth -and scroll in a direction tangential to the direction of scroll rotation and lateral to the longitudinal direction of movement of the band during tensioning. These frictional forces can cause the band, while being tightened, to be pushed to the side of the scroll support as it passes thereunder producing nonproductive resistance to scroll rotation and causing the band to cock relative to the desired plane of the clamp band. Such frictional forces tend to prevent lthe band from centrally passing through the scroll support and tightening flat upon the article being clamped, and -adversely affect the efiiciency of the clamping action produced.
Summary of the invention The clamp of the invention utilizes a scroll or spiral cam to circumferentially adjust the band or strap, to obtain the advantages of this type of drive, while overcoming the disadvantages of prior scroll driven clamps as described above.
In the construction of the clamp of the invention the scroll and its support are of a concise configuration which results in a clamp of only slight radial projection beyond the shape `of the `article being clamped. The scroll includes means to be engaged by a tool, usually a screwdriver, which is so located that the force imposed on the scroll by the tool, to maintain engagement therebetween, is in a substantially radial direction with respect to the clamp configuration and hose or pipe being clamped. Thus, the tool does not tend to rotate the clamp about 3,401,437 Patented Sept. 17, 1968 the hose during tighteninghas with worm drive hose clamps and the scroll permits a high mechanical advantage to be produced which results in effective clamping forces.
The clamp of the invention provides a more effective scroll-band teeth relationship than prior devices in that the scroll is related to the configuration of the band portion upon which the teeth are formed such that the circumferential forces produced in the clamp tend to keep the scroll and teeth engaged and, in fact, increase the effectiveness of the engagement of the scroll and teeth, rather than permitting these forces to tend to disengage the band teeth from the scroll. This advantage of the invention is accomplished by engaging the band teeth with the outer edge of the scroll cam and tilting the scroll such that the reaction forces imposed on the scroll by the band teeth tend to pivot the scroll into engagement with the teeth and toward the band. Additionally, the scroll tends to push the clamp band in the band takeup or tensioning direction, rather than pull, and the push force includes vectors disposed toward the band teeth, rather than away from the teeth.
An additional feature of the invention lies in the Shape of the scroll cam wherein at least two portions of the scroll cam will always be in engagement with two band teeth. This arrangement prevents excessive forces being produced at any single band tooth, such as would cause deformation or galling.
Another unique feature of the invention resides in the manner in which the teeth are formed on the clamp band or strap, and the manner in which these teeth relate to the `scroll cam. The band teeth are of a concave arcuate configuration as to correspond as closely as possible to the shape of the scroll cam. However, the teeth are asymmetric with respect to the width of the band portion on which they are formed. The band teeth are offset with respect to the longitudinal center of the associated band a sufficient distance to compensate for lateral or tangential frictional forces occurring between the scroll and the teeth engaged thereby during tightening of the clamp. Thus, the direction of the static force between engaged band teeth and scroll may be to the left of the band longitudinal axis. However, during rotation of the scroll during tensioning of the clamp, the frictional engagement between the teeth 4and scroll causes a force on teeth tangential to the scroll cam and to the right of the band axis. The configuration of the band teeth, and their relationship to the band axis, is predetermined such that the resultant kinetic force on the teeth and band during tensioning of the clamp is substantially parallel to the band axis. Thus, cocking of the band during tightening is prevented as no lateral shifting of the band occurs. The band is able to readily pass under the scroll and through the scroll support in the direction of its axis and will lie fiat on the article clamped such that effective clamping is assured.
Brief description of the drawing The above and other advantages of the invention arising from the details and relationships of the components of an embodiment thereof will be apparent from the following description and accompanying drawing wherein:
FIG. l is an elevational view of a circumferential clamp in accord with the invention,
FIG. 2 is a plan view of the clamp of FIG. l,
FIG. 3 is a detail, elevational view of the clampI of FIG. l, as taken along section III-III thereof,
FIG. 4 is an underside view of the retainer and inner end of the clamp as taken along section IV-IV of FIG. 1,
FIG. 5 is an enlarged, detail, diametrical, sectional, elevational view of the retainer, scroll body member, scroll projection, and band, as taken along section V-V of FIG. 2,
FIG. 6 is an enlarged bottom view of the scoll body member, illustrating the configuration of the scroll projection or cam,
FIG. 7 is an enlarged sectional view of the band, teeth and scroll as taken along section VII-VII of FIG. 5, and
FIG. 8 is a diagrammatical, sectional, elevational view of the scroll and the band teeth.
The circumferential clamp illustrated includes a fiexible `band or strap 10 which is normally formed of steel. The band is fiexible enough to permit radial contracting of the circle defined by the band during tensioning without producing undue resistance. The band includes an inner end portion 12 and an outer end portion 14. In the illustrated embodiment, the outer end portion 14 is provided with a plurality of teeth 16 which :are spaced in the longitudinal direction of the band and define a track thereon. The teeth 16 do not define a track extending the entire length of the band, i.e., the circumference thereof. However, the teeth may exist over the length of the band, if desired. Preferably, the teeth 16 are formed by a lancing operation from the metal of the strap and are defiected from the configu-ration of the strap in the direction of the strap outersurface 18 'to define edges 20. The teeth are evenly spaced and, as will be apparent from FIGS. 2, 3 and 7 are offset with respect to the Width of the band as will be described later in greater detail. It is desired that the teeth be of an arcuate configuration substantially corresponding to the maximum radial configuration of the scroll cam or projection with which they engage, as will later be apparent.
While the teeth 16 are shown as formed by a lancing operation, it will be appreciated that suitable teeth can be formed by coining or similar well-known manufacturing processes. It would also be possible to practice the concept ofthe invention by forming the teeth as a plurality of evenly spaced holes defined in the band, as is often ernployed with conventional worm drive hose clamps.
A scroll support or retainer 22 of a stamped steel construction is afiixed to the band adjacent the inner end 12. The retainer includes an inverted cup-shaped portion defied by a base portion 24 and a substantially cylindrical wall 26, the inner surface 28 of which forms a bearing surface for the scoll body member containing the scroll cam. A cylindrical opening 30 is defined in the portion 24 concentric with the cylindrical wall 26.
A pair of tabs 32 are formed on the retainer 22 located at substantially diametrical positions, whereby the tabs may project parallel to the wall 26 and then be bent under the band inner end 12, FIG. 4. The ends of the tabs 32 are provided with elongated portions 34 which include shoulders 36. The ends of the elongated portions 34 are received within recesses 38 defined in the band inner end through openings or slots 40 defined in the band, las will be apparent from FIG. 5. The axial width of the right slot 40, FIG. 4, is such that the shoulders 36 will engage the band adjacent the slot and, thus, prevent movement of the retainer in the axial direction of the band to the right as viewed in FIGS. 1, 4 and 5 during tensioning of the band. Therefore, it is appreciated that the retainer 22 is firmly afiixed to the band inner end in an economicalmanner requiring no extra components.
As apparent from FIGS. 1 and 5, the retainer cupshaped portion defined by base 24 and walls 26 is obliquely related to the circular configuration defined by the band 10 and this oblique relationship is such that the portion of the Wall 26 disposed in the direction of band movement during take-up or tensioning, i.e., toward the left, FIG. 5, is closest to the center of the circle defined by the band 10.
A generally cylindrical scroll body member 44 is re tained and rotatably supported within the retainer 22 on lbearing surfaces disposed adjacent the body member periphery, as is apparent from FIG. 5. The body member 44 includes a cylindrical surface 46 which is adapted to rotatably cooperate with the retainer inner surface 28, whereby the member 44 will be rotatably located in the body member in the desired angular relationship to the clamp components. A tab 42 extends from wall 26 and is bent under member 44 to maintain member 44 in the oblique relationship of the retainer and up against base 24.
The body member 44 includes a cylindrical boss 48 which extends through the retainer opening 30 and includes Ia screwdriver-receiving slot 50. Preferably, the slot 50 is of such depth that the edge of the opening 30 will serve as a guide to maintain a screwdriver within the slot during operation of the clamp.
The surface 52 of the body member 44 disposed toward the band inner end 12 is formed with a spiral scroll cam or projection 54, the configuration of which will be appreciated from FIGS. 5 and 6. The central portion of the lower surface 52 of the body member is open and the scroll cam does not extend to the center of the body member. However, in the illustrated embodiment, the scroll cam is of such configuration that approximately 2% turns are provided. Referring to FIG. 5, the surface 52 is beveled at 56 with respect -to the axis of rotation of the tbody member whereby the depth of the scroll cam will remain substantially constant and, yet, the most desirable relationship between the .scroll projection and the band teeth can be maintained. The tab 42 is closely related to the scroll projection to hold the member 44 in the retainer, yet does not interfere with the rotation of the scroll member 44.
With the components in the relationship shown in FIG. 5, it will be noted that the oblique angle of the axis of the retainer cup portion and body member, with respect to the curvature of the lband outer end 14 and band teeth, insures that the scroll cam 54 will only engage the teeth 16 on one side of the axis of rotation of the scroll body member 44 and scroll cam, and that the other side of the scroll cam will be out of engagement with the band teeth. In FIG. 5 the configuration of the teeth 16 is somewhat exaggerated for purposes of illustration.
The teeth 16 .are of an arcuate form which substantially corresponds to the maximum arcuate configuration of the scroll cam 54, FIG. 7, and the angle of the body mem- -ber bevel 56 is such that the degree of radial intermeshing lbetween the engaged scroll cam and teeth is substantially equal at the locations of engagement, as shown in FIG. 5. Thus, the forces being transmitted between the scroll cam and the teeth 16 are divided between `several teeth, always at least two, minimizing any tendency to over-stress or gall a band tooth.
In operation the circumferential clamp will be of a diameter larger than the hose, pipe, or other cylindrical article to be clamped and, therefore, may be slipped over the end of the article to be clamped. In some cases, where it is not possible to slip the clamp endwise over the hose, the clamp may be fully opened wherein the teeth 16 are yremoved from engagement with the scroll cam and the band opened up to encompass the article and thereupon the :band outer end 14 may be reinserted `between the body member 44 and the band inner end 12 until the band teeth engage the scroll cam 54.
Upon placing a screwdriver in the slot 50 and rotating the body member 44 in a clockwise direction, FIG. 2, the outer surfaces of the scroll cam 54 will mesh with and engage the teeth 16 and push the band outer end 14 to the left, FIG. 5. The portion 58 of the Iband inner end 12 1between the slots 40 forms a back-up portion for the outer end of the band and, thus, maintains the band teeth in a position to be engaged by the scroll cam.The configuration of the scroll cam 54 provides a high mechanical advantage between the rotation of the body member 44 and the rate of translation of the band outer end 14, thus permitting a high degree of tensioning -of the band 10. Upon the desired degree of tension being produced in the band 10, the screwdriver is removed from the slot 50 and the clamping operation is complete.
When it is desired to remove the clamp from the article being clamped, a screwd-river is again inserted in the slot 50 and the scroll body member 44 and scroll cam are rotated in the counterclockwise direction, FIG. 2, to cause the scroll cam to engage the rear surface 60 of 4the teeth 16 and translate the band outer end 14 to the right, FIG. 5.
The advantages derived from the configuration and relationship of the `band teeth 16 relative to -the scroll cam 54 are best apparent from FIG. 7. In FIG. 7 the longitudinal axis of the band portion 14 is represented at 62 and the off-set relationship of the teeth 16 relative to the axis 62 will be readily appreciated. Preferably, the centers of the circular segments forming teeth 16 are displaced slightly `with respect to -axis 62 and the center of the teeth occur on line 64 which is displaced from axis 62 in the direction of the main configuration of the teeth. In one embodiment of the invention the distance separating lines 62 and 64 is .O15 inch.
As the arc of teeth 16 is substantially equal to the maximum arc of the scroll cam 54 the engagement between the scroll cam and the teeth will occur at a limited area of the cam and teeth to substantially produce point contact between the cam and teeth, except when the maximum radius of the cam is engaging a tooth. Thus, due to the spiral conlfiguration of the scroll cam, the shape of the teeth 16 and the placement of the teeth on the 4band portion 14 the contact between the cam scroll and teeth will occur along line 66, where the center of the scroll cam 54 is represented at 68.
Rotation of the sc-roll body 44 is in a clockwise, or band tension direction, will produce a lateral force on the band portion 14 in the direction of the iarrow 70 due to the friction existing between scroll cam 54 and the engaged teeth 16 as the cam is wiped across the teeth. Normally, the existence of the frictional forces in the direction of arrow 70 would cause the band portion 14 to be shifted intoengagement with the upper tab 32, FIG. 7, which would produce a very objectionable resistance to tightening of the clamp, as well as possibly cause the band to cock on the article being clamped and not lie fiat thereon. However, as the radial force exerted on the band portion 14 'by the scroll cam 54 occurs along line 66, rather than parallel to the axis 62 of the band, the resultant of the forces exerted by the scroll cam on t-he teeth 16 in the indicated directions of lines 66 and 70 occurs along line 72 which is parallel to axis 62. Thus, the band portion 14 will stay centered 4between tabs 32 as the clamp is tightened and unnecessary frictional losses are prevented and the band will remain properly oriented to the article being clamped.
In FIG. 8 a diagramatic representation of the band portion 14 and the scroll body 44 is presented to illustrate the advantage of inclining the body 44 in the direction of band movement during tensioning, and using the outside surface of the scroll cam to push, rather than pull against the band teeth 16.
Band movement during tensioning is represented by arrow 74, therefore, the reaction force of the band teeth on the scroll cam will be in the direction of arrow 76. As the body 44 is supported by the retainer 22 at a greater radial distance from the center of the article being clamped than force 76, and as the body 44 is tilted toward the direction of band movement during tensioning, the tendency of force 76 is to twist the body 44 in the direction indicated by arrow 78. This tendency to twist body 44 in the direction 78 will force the scroll cam 54 portions in engagement with teeth 16 toward the engaged teeth and thereby increase, rather than decrease, the extent and eiciency of the engagement between the scroll cam and engaged band teeth.
The use of the scroll projection drive permits the body member 44 and the retainer 22 to be of a very concise configuration and the radial dimension of the band tensioning -means is considerably less than the radial dimension of the more conventional worm drive tensioning means. An additional advantage arising from the use of the scroll drive as utilized in the illustrated arrangement lies in the fact that when using a screwdriver to rotate the body member 44, the force exerted on the screwdriver to maintain the engagement with the slot 50 does not tend to cause the clamp to slip around the article being clamped, as with a conventional worm drive-type hose clamp. With the invention, the force applied to the screwdriver to maintain engagement with the slot 50 is substantially radial and, thus, there is no tendency for the clamp to be pushed around the hose during tightening.
It will be appreciated that rather than employing a screw slot 50, the boss V48 could extend far enough from the retainer portion 24 to permit a wrench to be applied thereto upon the provision of flats or a hexagonal configuration on the boss.
Other modifications to the inventive concept may be apparent to those skilled in the art without departing from the spirit and scope of the invention and it is intended that the invention be defined only by the following claims.
What is claimed is:
1. A circumferential clamp comprising, in combination, an elongated fiexible tension member adapted to circumscribe the article to be clamped, said tension member including first and second spaced portions, said second portion having a longitudinally extending central axis, a plurality of teeth defined on said tension member second portion evenly spaced in the longitudinal direction thereof and asymmetrically related to said longitudinal axis, a retainer fixed relative to said tension member first portion and overlying said member second portion and teeth, a scroll body member rotatably supported and retained in said retainer, means defined on said body member for rotating said body member, a scroll cam defined on said body member having an axis coincident with the axis of rotation thereof, said scroll cam engaging at least one of said teeth whereby rotation of said body member and cam translates said second portion in a tensioning direction, said teethbeing soV disposed on said second portion such that the radial force on the engaged tooth resulting from engagement with the scroll cam is laterally and obliquely disposed of said second portion longitudinal axis on the lateral side of said axis opposite to the relative direction of rotation of said scroll cam and the engaged tooth when said flexible member is being tensioned whereby the combination of the radial and lateral frictional forces imposed on the engaged tooth by said scroll cam results in a kinetic force imposed on the engaged tooth substantially parallel to said second portion longitudinal axis.
2. A circumferential clamp as in claim 1 wherein said teeth are of an arcuate concave configuration having a radius substantially corresponding to the maximum radius of said scroll cam.
3. A circumferential clamp as in claim 2 wherein said teeth are of a concave cylindrical segment configuration and the center of generation of said teeth lies on a line longitudinally disposed on said flexible member second portion and laterally off-set with respect to said axis on the same side of said axis as related to the location of the major portion of said teeth relative to said axis.
4. A circumferential clamp as in claim 1 wherein said scroll cam consists of at least two complete convolutions and at least two teeth are engaged by said cam during tensioning of said clamp.
5. A circumferential clamp as in claim 4 wherein said scroll cam includes a radially outwardly facing surface,
and means maintaining said retainer and body member obliquely disposed to said tension member second portion in the direction of the length and inclined toward the direction of movement of said second portion relative to said retainer during tensioning of said flexible member whereby said scroll cam outwardly facing surface engages at least two of said teeth in the direction of movement of said second portion during tensioning of said flexible member and reaction forces between said teeth and scroll cam tend to bias the teeth engaged portion of the scroll cam toward the engaged teeth.
References Cited UNITED STATES PATENTS FOREIGN PATENTS lO/.1964 France.,
DONALD A. GRIFFIN, Primary Examiner.