MXPA00009073A - Strut for planar one-way clutch - Google Patents

Abstract

A strut (16) for mechanically coupling a first member (12) to a second member (14) in a planar one-way clutch (10) is formed in a progressive die from a length of cold-formed metallic stock material (50) such that the strut's diametrical member-engaging end surfaces (24, 36) are coextensive with a pair of cold-formed surfaces (52) of the stock material. A pair of oppositely-projecting"ears"(28) are integrally formed on the strut proximate to one (24) of its end surfaces at one station (62) of the progressive die. The ears cooperate with a complementary recess (32) within a pocket (22) formed in the first member's planar clutch face (20) to thereby nominally position and maintain the one of the strut's end surfaces within the pocket. A surface (44) on each ear is preferably coined at another station (56) of the progressive die to thereby provide a relief which prevents deleterious contact between the ears and the opposed clutch face (32) of the second member (12).

Description

"UNI-DIRECTIONAL CLUTCH FOR PLANE" TECHNICAL FIELD The invention relates to flat unidirectional clutches wherein a relatively thin flat strut selectively provides a mechanical coupling between the generally flat opposed faces of a pair of coaxial rotating members.

ANTECEDENTS OF THE TECHNIQUE The clutches are used in a wide variety of applications to selectively couple the energy of a first rotating "impeller" member, such as a disk or impeller plate with a second "driven" member, independently rotating, such as a driven plate or disk. In a known variety of clutches, which are commonly referred to as "uni-directional" or "free-rotation" clutches, the clutch "engages" to mechanically couple the drive member to the driven member only when the drive member tries to rotate in a first direction in relation to the driven member. Once engaged in this manner, the clutch will release or disengage the driven member from the driving member only when the driving member rotates in a second opposite direction relative to the driven member. In addition, the clutch otherwise allows the driven member to rotate freely in the second direction relative to the driven member. This "free running" of the driving member in the second direction in relation to the driven member is also known as the condition of "free rotation". One of these known uni-directional clutches employs nominally coaxially placed, juxtaposed, impeller-driven members which have generally flat clutch faces in closely spaced axial opposition. "These" flat "uni-directional clutches, as disclosed by Fran in U.S. Patent Number 5,449,057 and by Ruth et al. In U.S. Patent No. 5,597,057, typically include a plurality of recesses or" cavities "formed in the face of the drive member and at least as many recesses or "grooves" formed in the face of the driven member A thin flat belay or strut, whose width is significantly less than its length, is carried into each of the cavities of the driving member in such a way that a first longitudinal end of each strut can easily engage and lean against a radial shoulder defined by its respective cavity in the driving member The second longitudinal end opposite the strut is pushed towards and against the face of the driven member, for example , by means of a spring placed in the cavity between the strut, when the driving member rotates in the first direction relative to the impu The second end of at least one strut engages and then bears against a radial shoulder defined by a notch in the driven member, after which the strut is placed in compression and the driven member engages for rotation with the member. driving. When the driving member rotates in the second direction relative to the driven member, a ramp surface defined by other portions of the notches of the driven member pushes the second end of each strut back to the driving member, after which it is allowed to the driving member rotates freely in the second direction relative to the driven member. In order to improve the quality of the coupling of the strut member, the coupling ends of the member of each strut each are provided with an inclined surface, which remains nominally parallel with one another. And, in U.S. Patent Number 5,597,057, Ruth et al. Also discloses the use of a strut whose first end includes a pair of "arms" projecting oppositely or "lugs", the upper surface of which is placed as a ramp to prevent interference between the top of each lug and the driven member as the second end of the strut is pushed towards the driven member. As an example, when the radial shoulders defined in each of the driving and driving members extend in a direction essentially perpendicular to each generally flat clutch face of the member, the upper ramp surface of each lug is inclined more or less at the same angle as each one of the inclined end surfaces of the strut. A portion of each lug adjacent the inclined surface of the first end of the strut is also preferably removed to form a relief that ensures that the lugs of the strut are not loaded during clutch engagement. Although the struts, with parallel inclined end surfaces and ramp lugs provide these flat uni-directional clutches of the prior art with increased performance, the presence of these particularities significantly increases the manufacturing costs associated with these thin flat struts. For example, in accordance with a known process, the struts used in these flat uni-directional clutches are thinly insulated in laterally adjacent pairs of relatively thin coil material in a five-step process: (1) the coil material is wedged to provide the appropriate ramp angle in that which will become the strut lugs; (2) the material is cut into "U" to define the outer periphery of the lugs / (3) the material is further trimmed to define the sides of the strut; (4) The edges of the continuous belt are formed downwards by bending the continuous belt over a horn to thereby provide an inverted "V", each leg of which descends to the nominal angle with which the surfaces are to be formed coupling end of the strut member; and (5) the lateral pair of struts are insulated from the descending legs of the continuous belt, one of each leg, as the punch pierces through the belt at an angle. As a further disadvantage, this prior art process is carried out at a relatively slow rate of possibly about 18 to 20 strokes per minute. The inclined end surfaces of these prior art struts typically exhibit approximately 10 percent significant detachment and rolling. The resulting end surface distortions reduce the amount of contact area of the coupling end surface of the member available in each strut, even after the subsequent expensive machining of the end surfaces. Possibly most significantly, the difficulty of controlling both the descending angle of the tape continues as it is bent above the horn and the subsequent angle at which the punch cuts each of the end surfaces of the prop is combined with the distortions of the end surface to result in reduced dimensional control, including a relatively poor control of the angle at which each of the end surfaces of the strut is inclined, and an inherent loss of parallelism between the end surfaces of the strut.

COMPENDIUM OF THE INVENTION Under the invention, a thin flat strut for a flat uni-directional clutch is formed of a length of cold formed metal material such that the mating end surfaces of the strut diametric member are coextensive with a pair of lateral edge surfaces of the strut. material. Preferably, at least one side edge surface of the material includes a substantially planar section that is inclined relative to the top face of the material. More preferably, both the lateral edge surfaces of the material forming the coupling surfaces of the diametric strut member include essentially planar inclined sections, and these essentially planar sections are essentially parallel with respect to each other. According to a particular feature of the invention, the strut preferably includes a pair of opposingly projecting lugs formed integrally on either side of the strut proximate a first of the mating surfaces of the strut member. The lugs cooperate with a recess or complementary cavity formed, for example, on the face of the generally flat clutch of the driver member to thereby nominally position and maintain the first mating surface of the strut member within the cavity. Preferably, a ramp surface is formed on each lug to avoid any possible interference between the lugs and the opposite clutch face of the driven member, when the strut is otherwise pivoted to present its second end surface for engagement with the lug. the notches of the driven member. A second surface of each lug, which is nominally an extension of the first engagement surface of the strut member, is preferably also cut out to form a relief on each lug. The reliefs ensure that the lugs do not carry mating loads when the strut couples the driving member with the driven member. Under the invention, a method for manufacturing a thin flat strut includes providing a stretch of thin cold formed material having a pair of side edge surfaces, wherein at least one lateral edge surface of the material includes an essentially planar section; and forming the strut of the material in such a way that the diametric end faces of the strut are coextensive with the lateral edge surfaces of the material. More specifically, in an exemplary method for carrying out the invention, the strut is formed by advancing the material through a plurality of matrix stations such as in a progressive matrix. By way of example, in the exemplary method for manufacturing struts, the material is advanced through a first trimming station to remove the material from a lateral edge surface of the material at a first location thereof, thereby providing the edge relief in each of which will subsequently become the integral lugs of the strut, removing the material to prevent the flow of harmful material during a subsequent coining step, and defining a pilot hole in the material to facilitate the matching of the material in relation to the subsequent matrix stations. The trimmed material is then advanced to a second coining station to wedge a surface of the material adjacent to the first location thereof, whereby the ramp surfaces of what will ultimately be each lug of a strut are formed of course. In a third flattening station, the material is flattened to remove any upward shifting induced in the material by wedging. In a fourth cutting station, the additional material is removed from the material next to the first location thereof by which the strut is cut from the material. As a further particularity of the method of the invention, the sides cut in this manner from each strut are essentially more insulated than the sides of struts produced by prior art processes.

BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a side elevation view of an exemplary planar uni-directional clutch incorporating the struts in accordance with the invention; Figure 2 is a detailed view of the clutch of Figure 1; Figure 3 is a sectional view of the exemplary clutch on line 3--3 of Figure 1 illustrating a strut in its "engaged" or "engaged" condition; Figure 4 is a sectional view of the exemplary clutch on line 4--4 of Figure 3; Figure 5 is a sectional view of the exemplary clutch similar to that shown in Figure 4, but illustrating the strut in the condition of "free wheel" or "free rotation"; Figure 6 is a perspective view of an exemplary strut in accordance with the invention; Figure 7 is a side view of the exemplary post shown in Figure 6; Figure 8 is a top plan view of the exemplary post shown in Figure 6; and Figure 9 is a strip project showing the operations carried out in each station within a progressive matrix, with shading that identifies the operations of trimming or punched and deblocking showing wedging or flattening operations.

BEST MODE FOR CARRYING OUT THE INVENTION Referring to the drawings, Figures 1 to 5 show an exemplary flat uni-directional clutch 10 including an impeller member 12, a driven member 14 and a plurality of struts 15 that function to mechanically couple the driving member 12 with the driven member 14 only when the driving member 12 rotates in a first direction 18 relative to the driven member 14. More specifically, the driving member 12 includes a generally flat clutch face 20 having a plurality of recesses or cavities 22 defined therein. Each cavity 22 is adapted to nominally receive and retain a particular strut 16, such that a first end surface 24 on the strut 16 is positioned in opposition to, and then will workably engage a radial shoulder 26 defined in the cavity 22 when the drive member 12 is rotated in the first direction 18. Although the invention proposes the use of any suitable arrangement whereby the first end surface 24 of the strut is nominally positioned within the respective recess 22 of the strut, in the clutch 10. illustrated exemplary, each strut 16 includes a pair of opposingly projecting lugs 28 extending laterally from the strut 16 proximal to its first end 24. Each of the tabs 28 of the strut cooperatively engage the radially internal and radially outer complementary surfaces 30 of the cavity so as to nominally place the first end 24 of the strut in its cavity ad 22 respectively. The driven member 14 similarly includes a generally flat clutch face 32 which is positioned in axial opposition closely spaced to the face 20 of the driving member 12. The face 32 of the clutch of the driven member also has a plurality of recesses or notches 34 that they are defined in it. Each of the notches 34 in the driven member 14 is adapted to receive the free end of the determined strut 16 when the free end of the strut is pushed towards the notch 34, for example, by a spring 38 seated below the strut 16 in the cavity 22 of the driving member. Each notch 34 includes a bearing surface 40 with which a second end surface 36 operably engages in the strut 16, when the driving member 12 is rotated in the first direction 18 relative to the driven member 14. As can be seen more clearly in the amplified views of the strut 16 shown in Figures 6 to 8, the first and second end surfaces 24, 36 of the strut member engagement each include essentially planar sections that are inclined relative to the upper face 42 of the strut 16, as illustrated in Figures 6 to 8. The essentially planar sections of the first and second end surfaces 24, 36 of the strut are in themselves essentially parallel with respect to each other. In the exemplary clutch illustrated in the drawings, the first and second end surfaces 24, 36 are inclined to a nominal angle of approximately 16 degrees relative to the upper face 42 of the strut. In accordance with another feature of the invention, a surface 44 with ramp is formed on each lug 28 to avoid any possible interference between the lugs 28 and the opposite clutch face 32 of the driven member 14 when the strut 16 otherwise moves to pivoting upwards to present its second end surface 36 for engagement with the clutch face 32 of the driven member. A second surface 46 of each lug 28 is also preferably cut out to form a relief on each lug 28. The reliefs formed by the second surfaces 46 of the lug ensure that the lugs 28 do not carry mating loads when the strut 16 engages the member. impeller 12 with the driven member 14.

An exemplary method for manufacturing the strut of the invention is illustrated diagrammatically by the strip project 48 shown in Figure 9, where the shading identifies the cutting or punching operations and the dotting identifies the coining or flattening operations. The exemplary method includes providing a stretch of thin cold formed material 50 such as a cold drawn or cold wound wire of SAE 1065 spheroidal or annealed steel, having its side surfaces 52 inclined to a predetermined angle; and forming the strut 16 of the material 50 such that the diametric end surfaces 24, 36 of the strut 16 are coextensive with the side edge surfaces 52 of the material 50. More specifically, the exemplary method of Figure 9 includes making advancing the material 50 to a first matrix station (which is generally indicated at 54), and trimming the material 50 at the first matrix station 54 to define a pilot hole, so as to define the second surface 46 in what is subsequently it will define as the lugs 28, which project oppositely from the strut to prepare the material 50 for a subsequent coining operation, and in this way otherwise reduce the amount of continuous tape between the adjacent struts 16.

The exemplary method of Figure 9 continues to advance the trimmed material 50 to a second station (which is generally denoted at 56), and wedge the upper surface of the material 50 into the second station 56 to thereby define the ramp surface 44. in the first lug 28 of the strut 16 that is forming immediately downstream of the cut-away location 58 of the material 50. In this regard, it will be noted that the relief provided by the trimming operation that was carried out in the first Station 54 preferably prevents undesirable projections or burrs which could otherwise result in the flow of material detrimental during coining. The coined material 50 is then advanced to a third matrix station (which is generally indicated at 60) wherein the material 50 is flattened to thereby reduce any curvature that could have been induced in the material 50 during coining. Finally, the flattened material 50 is advanced to a fourth cutting station (which is generally indicated at 62) where the additional continuous strip material near an advanced trimmed location 58 is removed, and the finished strut is cut from the strip. In this regard, it will be noted that a proposed mismatch between the first step of trimming and the cutting step, which provide the stepped side faces 64 of each strut as seen in Figures 6 to 8, can be used to further prevent the detrimental formation of burrs on the 16th strut during cutting. As mentioned above, in the exemplary method, a single progressive matrix (not shown) can be used to combine each of the four aforementioned matrix stations 54, 58, 60, 62, with each step of advance indicated taking to in the material 50 simultaneously, with the coincidence of the strip relative to the matrix being secured through the use of the pilot holes formed in the first matrix station. As a result, in accordance with another feature of the invention, the exemplary method produces a strut 16 per stroke of the progressive die, at a rate of operation considerably higher than that which is employed in the fine stamping process of the prior art for make these struts. By way of example, it is currently calculated that a progressive matrix operation according to the strip project 48 illustrated in Figure 9 is capable of at least providing approximately 70 strokes per minute. It will be appreciated that the strut 16 produced in accordance with the exemplary method of Figure 9 may undergo further processing in a manner known to those skilled in the art. Therefore, in the exemplary method where the material is SAE 1065 steel spheroidized and annealed, each stripped post is then dropped or collapsed to achieve an appropriate edge / corner break, such as a maximum of 0.038 cm; hardened at 843 ° C; cooled with oil; and tempering at 177 ° C to a minimum hardness of Rockwell-C 53. In accordance with a particularity of the invention, the exemplary method of Figure 9 presents a significantly more demanding dimensional control through the inclined end surfaces 24, 36. of the strut including the degree of parallelism between the inclined end surfaces 24, 36, and the member engagement face contact area which is defined on each inclined end surface 24, 36, because these end surfaces 24, 36 are defined per se by the dimensions of the untreated material 50. In addition, the end surfaces 24, 36"as stretched" or "as cold formed" each strut 16 made in accordance with the invention has an essentially continuous grain structure in which the individual grains extend in essentially parallel relationship. In this way, the exemplary method of Figure 9 provides both improved strut quality and improved functionality when compared to struts produced by the prior art fine stamping processes. In accordance with still another feature of the invention, the exemplary method generates less waste or debris than the fine punching processes of the prior art because a considerable portion of the periphery of each strut 16 is defined by the untreated material instead as a function of the fine punching process.

Claims (16)

CLAIMS:

1. A thin flat strut, for a flat uni-directional clutch comprising a first end surface and a second diametrically opposite end surface of the first end surface, wherein the strut is formed of a length of cold formed metal material which has a pair of side edge surfaces such that the first and second end surfaces of the strut are coextensive with the lateral edge surfaces of the material, and wherein at least one side edge surface of the material includes an essentially planar section .

The strut of claim 1, wherein the material includes an upper face, and wherein the essentially planar section of at least one side edge surface of the material is inclined relative to the top face of the material.

The strut of claim 1, wherein the side edge surfaces of the material each includes an essentially planar section and wherein the essentially flat sections of the side edge surfaces of the material are in essentially parallel relationship.

4. The strut of claim 1, which includes a pair of integrally formed lugs projecting oppositely close to the first end surface of the strut.

5. A method for manufacturing a thin flat strut for a flat uni-directional clutch, wherein the strut includes a pair of diametric end surfaces, the method comprising: providing a stretch of thin cold formed material having a pair of surfaces side edges, wherein at least one lateral edge surface of the material includes a substantially planar section; forming the strut of the material in such a way that the diametric end surfaces of the strut are coextensive with the lateral edge surfaces of the material.

6. The method of claim 5, wherein the training includes advancing the material through a plurality of matrix stations.

The method of claim 6, wherein the first of a plurality of matrix stations includes a pick-up station for removing material from each lateral edge surface of the material at a first location.

8. The method of claim 7, wherein a second of the plurality of matrix stations includes a coining station after the cutting station for coining a material surface close to the first location thereof.

The method of claim 8, wherein the third of the plurality of matrix stations includes a flattening station after the coining station to flatten the material.

The method of claim 9, wherein the fourth of the plurality of matrix stations includes a cutting station for removing the additional material from the material near the first location thereof, wherein the strut is cut from the material.

11. A method for manufacturing a thin flat strut for a flat uni-directional clutch, wherein the strut includes a pair of inclined end surfaces in essentially parallel relationship, the method comprising: providing a stretch of thin cold formed material having a pair of side edge surfaces, wherein the side edge surfaces of the material include essentially planar sections in substantially parallel relationship with respect to each other; and forming the strut of the material in such a way that the diametric end surfaces of the strut are coextensive with the lateral edge surfaces of the material.

The method of claim 11, wherein the training includes advancing the material through a plurality of matrix stations.

The method of claim 12, wherein the first of the plurality of matrix stations includes a trimming station for removing the material from each lateral edge surface of the material at a first location.

14. The method of claim 13, wherein the second of the plurality of matrix stations includes a coining station after the cutting station for coining a material surface close to the first location thereof. The method of claim 14, wherein the third of the plurality of matrix stations includes the flattening station after the coining station to flatten the material. The method of claim 15, wherein a fourth of the plurality of matrix stations includes a cutting station for removing additional material from the material near the first location thereof, whereby the strut is cut from the material.