Abstract:
A tolerance equalizing element includes at least two support bodies ( 120, 122 ) which are in threaded engagement with one another such that the axial dimension of the tolerance equalizing element can be adjusted by relative rotation of the support bodies ( 120, 122 ), at least one of the support bodies ( 120, 122 ) including a helical spring which is wound from a wire having a rectangular cross-section, and the rectangle forming the cross-section of the wire is oriented such that its sides extend obliquely relative to the axis of the helical spring.

Description:
BACKGROUND OF THE INVENTION 
     The invention relates to a tolerance compensation member having at least two support bodies that are in threaded engagement with one another such that the axial dimension of the tolerance compensation member can be adjusted by relative rotation of the support bodies. 
     Examples of tolerance compensation members of this type have been described in DE 298 07 967 U1, EP 1 118 605 A1 and EP 1 215 401 A2. 
     The tolerance compensation members serve in particular for forming a tensed connection between two construction members by means of a connecting bolt that is inserted through the support bodies which have an annular shape. One of the support bodies is in engagement with the connecting bolt via a slide coupling so that, when the connecting bolt is screwed into one of the two constructions members to be connected, the support body is entrained frictionally and is thereby rotated relative to the other support body. In this way, the axial dimension of the tolerance compensation member is increased during the process of screwing-in the bolt, until the compensation member bridges the space between the two construction members. Then, the slide coupling permits the connecting bolt to be screwed-in further whereas the two support bodies maintain their position relative to one another. 
     In the known tolerance compensation members, the support bodies are formed by cylindrical metal parts that are held in engagement with one another via cut screw threads, e.g. left-handed screw threads. 
     DE 20 2011 052 036 U1 describes a tolerance compensation member wherein one support body is formed by a helical spring that is wound from a wire. The wire has a rectangular cross-section and is moved such that the inwardly and outwardly facing sides of the rectangle extend in parallel with the axis of the helical spring. 
     SUMMARY OF THE INVENTION 
     It is an object of the invention to provide a tolerance compensation member which can be manufactured simpler and cheaper. 
     According to the invention, this object is achieved with the features indicated in the independent claims. 
     In one embodiment, at least one of the support bodies comprises a helical spring that is wound from a wire with a non-rectangular cross-section and forms the screw thread of this support body. In another embodiment, the cross-section of the wire is rectangular, but the wire is wound such that its sides are inclined relative to the axis of the helical spring. 
     Thus, in both embodiments, the support body or at least the threaded part thereof can be formed simply by winding a wire that has a suitable profile, with the thread turns of the screw thread being formed by the profile of the wire. In this way, laborious processes for cutting-type machining of the metal, such as milling or thread cutting, can be eliminated. 
     Useful details of the invention are indicated in the dependent claims. 
     In an advantageous embodiment, the helical spring is formed such that its turns are blocked against one another when the spring is non-loaded. Then, the turns of the helical spring may optionally be connected to one another at the faces with which they engage each other, for example by gluing, soldering or welding, e.g. by resistance welding, so that a rigid metal body is formed. 
     Preferably, both support bodies are formed by helical springs. 
     Since practically no mill cutting type machining is required for the threaded parts, high-strength spring steels may be used for the helical springs. This has the advantage that a high supporting force is achieved even when the support bodies are in threaded engagement with one another over only a small distance. Consequently, even when the minimum axial dimension of the tolerance compensation member is small, it is possible to achieve a large adjustment range, so that correspondingly large distance tolerances can be compensated. 
     In a particularly preferred embodiment, the cross-sectional shape of the wire corresponds to a tipped square, so that the parts with which the turns of the helical spring are in block engagement with one another are essentially formed only by the corners of the square cross-sections. The corners of the square that will then face inwardly and outwardly relative to the helical spring will then form both, an internal thread and in external thread. 
     According to a useful further development of the invention, a terminal plate is arranged on at least one end of the helical spring, the plate having an annular groove that is complementary to the last turn of the helical spring. Consequently, when the last turn of the spring is received in the groove, the thread pitch may be compensated, so that the terminal plate will be in fitting engagement with the end of the helical spring and will have an external surface that is oriented at right angles to the axis of the helical spring and therefore forms a suitable support surface for supporting one of the construction members to be connected. In this way, laborious face grinding of the helical spring can be avoided. The groove in the terminal plate may be formed for example by punching. Eventually, a stable support body with end faces extending precisely at right angles to its axis can be obtained in this way at low costs. 
     When both support bodies are formed by helical springs, the terminal plates may have two concentric grooves, one for the end of each of the two springs. The ends of the grooves, where their depth is greatest, will then also form an abutment for the end of the wire and assist in preventing the terminal plate from being rotated relative to the helical springs. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Embodiment examples will now be explained in conjunction with the drawings, wherein: 
         FIG. 1  is an axial section of a connecting device having a tolerance compensation member according to the invention in a condition before the connection is established; 
         FIG. 2  shows the connecting device according to  FIG. 1  in the condition after the connection has been established; 
         FIGS. 3 to 7  shows examples of helical springs that are wound from wires that have different cross-sectional shapes; 
         FIG. 8  is an axial section of a tolerance compensation member according to another embodiment; and 
         FIGS. 9 and 10  are sectional views of the tolerance compensation member according to  FIG. 8  in two different adjustment positions, with the plane of the section being rotated by 90° relative to  FIG. 8 . 
     
    
    
     DETAILED DESCRIPTION 
       FIG. 1  shows a connecting device that comprises a connecting bolt  10  and a tolerance compensation member  12  and serves for connecting a first construction member  14  to a second construction member  16  with a spacing formed therebetween. 
     The connecting bolt  10  is inserted through a bore of the first construction member  14  and is screwed into a threaded bore  18  of the second construction member  16 . The tolerance compensation member  12  serves as a spacer between the construction members  14 ,  16 . It comprises an outer support body  20  that is configured as a helical spring and is supported at the second construction member  16 , and an inner support body  22  that is also configured as a helical spring and is supported (in the final condition) at the first construction member  14 . 
     In the example shown, the outer support body  20  is a left-handed spring wound from a wire that has a non-rectangular cross-section, in this example an L-shaped cross-section with rounded or chamfered edges. When the helical spring is not tensioned, its windings are in blocking engagement with one another. The legs of the L-shaped wire cross-sections that project inwardly, together, form an internal screw thread. 
     The inner support body  22  is wound, left-handed and with blocking turns, from a wire that has also an L-shaped cross-section. The cross-sections of the wires of the support bodies  20  and  22  are complementary to one another and, together, form a rectangle. Thus, the windings of the inner support body  22  form a an external screw thread that is in engagement with the internal screw thread formed by the support body  20 . 
     In the example shown, the support body  20  is insert-molded or pressed or glued into a plastic socket  24  that may also fill the internal space of the helical spring in the lower part thereof and further has elastic claws  26  with which the socket  24  and, consequently, the support body  20  may be held non-rotatably on the second construction member  16 . 
     The inner support body  22  has its top end connected, e.g. welded, to a metal ring  28 . The interior of the metal ring  28  and of the support body  22  accommodate a plastic sleeve  30  the top and bottom ends of which are snap-fastened to the top and bottom ends of the support body  22  so as to hold the windings thereof in blocking engagement. 
     The windings of the outer support body  20  are held together by the socket  24  in this example. 
     Optionally, the windings of the support bodies can be welded to one another, so that an even stronger cohesion may be achieved. Particularly suited for this purpose is a resistance welding method wherein a current pulse passes through the wire that forms the helical spring from one end of the spring to the other. Then, the electrical resistance will be largest at the faces where the individual windings of the wire are engaging each other, so that the metal of the wire will be heated locally at these engagement faces and weld the individual turns together. 
     In this example, the sleeve  30  inside the inner support body  22  serves also for mounting two spring bows  32  that are arranged diametrically opposite to one another and have their top and bottom ends received in respective pockets of the sleeve  30 , whereas their inwardly bulging central part projects inwardly through a window of the sleeve  30 . Optionally, the spring bows  32  may also be formed in one piece with the sleeve  30 . 
     In the condition shown in  FIG. 1 , the inner support body  22  has been screwed-in completely into the outer support body  20 , so that the metal ring  28  almost rests on the top end of the socket  24  and the uppermost turn of the outer support body  20 , whereas a certain gap exists between the construction member  14  and the metal ring  28 . 
     In order to connect the construction members  14  and  16  with one another in such a manner that the relative spacing as shown in  FIG. 1  is maintained, the connecting bolt  10  is inserted through a bore of the member  14  and into the inner support body  22 . The threaded part of the bolt will thereby force the spring bows  32  outwardly and will deform them elastically, because the top and bottom ends of the bows are supported at the internal surface of the support body  22 . Thus, a certain resistance opposes to the further thrust-in movement of the connecting bolt  10 , but this resistance can be overcome, so that the bolt may be pushed further until it reaches the threaded bore  18  of the member  16 . 
     Subsequently, the bolt  10  is screwed into the threaded bore  18 . As the spring bows  32  are tightened against the periphery of the threaded part of the bolt, there is a relatively high friction between the external screw thread of the bolt  10  and the spring bows  32 , so that the spring bows are entrained in rotary direction. Since the spring bows  32  are immobilized in circumferential direction in the respective pockets of the sleeve  30 , the sleeve  30  is also entrained in rotary direction. As the sleeve  30  is snap-fastened to the support body  22 , the inner support body  22  and the metal ring  28  will also be driven to rotate, clock-wise when seen in the direction in which the bolt  10  is screwed in, because the connecting bolt  10  has a right-handed screw thread. 
     In contrast, the outer support body  20  is prevented from rotating by the socket  24  and the claws  26  that engage the member  16 . Consequently, the inner support body  22  rotates relative to the outer support body  20 , and, due to the left-handed screw thread with which the support bodies are in engagement with one another, the inner support body  22  is upwardly screwed-out of the outer support body  20  against the direction in which the connecting bolt  10  is screwed-in, so that the metal ring  28  approaches the construction member  14 . When the metal ring  28  abuts at the member  14 , the further outward screwing movement of the support body  20  is opposed by a larger resistance, so that the slide coupling formed by the threaded part of the connecting bolt  10  and the spring bows  32  will start to slip. The inner support body  22  and the metal ring  28  will then remain stationary in their position as the connecting bolt  10  is screwed further into the member  16 . Finally, the condition shown in  FIG. 2  is reached in which the head of the connecting bolt  10  engages the member  14  and the construction members  14  and  16  are tensed from opposite sides against the tolerance compensation member  12  which assures the desired spacing between these construction members. 
       FIGS. 3 to 7  show examples of other possible designs of the inner and outer support bodies. In  FIG. 3  an outer support body  20   a  is formed by a helical spring that is wound from a wire with a round cross-section, with the windings being in blocking engagement. Similarly, an inner support body  22   a  is formed by a blocked helical spring wound from round wire. Due to the round cross-section of the wire, the internal surface of the outer support body  20   a  forms, between the individual turns, helically extending recesses into which the outer apexes of the turns of the inner support body  22   a  may engage, so that a threading engagement between the two support bodies is achieved. 
       FIG. 4  shows an example in which an outer support body  20   b  is formed by two nested helical springs  34  and  36  the turns of which are arranged alternatingly and are in engagement with one another. The spring  34  has a somewhat smaller diameter than the spring  36  and thereby forms an internal screw thread the thread grooves of which are wider and deeper than in  FIG. 3 . A corresponding outer screw thread of an inner support body  22   b  may engage into this internal screw thread. In the example shown here, the inner support body is a milled metal part having a rolled or cut external screw thread. 
       FIG. 5  shows an embodiment in which, again, both support bodies  20   c  and  22   c  are wound from wire. What has been shown here is only a part of the peripheral wall of the support bodies being in threaded engagement with one another. In this example, the wire of both support bodies has a T-shaped cross-section. The cross bars of the “T” are blocked against one another whereas the central webs of the “T” form the engaging thread grooves and ridges. 
     In  FIG. 6 , an outer support body  20   d  and an inner support body  22   d  are wound from a wire the cross-sectional shape of which is similar to the L-shape shown in  FIGS. 1 and 2 , but with the difference that the complementary thread grooves and ridges have inclined flanks  38 . 
     Finally,  FIG. 7  shows a section of a part of an inner support body  22   e  that is wound from a wire with a hexagonal cross-section. The corners of the hexagon on the inner side of the helical spring form 90° corners, so that the turns of the wire will form a smooth internal surface of the helical spring, whereas external thread grooves  40  with a triangular cross-section are formed on the outward side. A corresponding outer support body may be wound from a wire that has a matching cross-sectional shape. Optionally, the outer support body may also have a conventional machine screw thread that is complementary to the outer screw thread of the support body  22   e.    
       FIGS. 8 to 10  show a tolerance compensation member  112  according to another embodiment. The function is the same as that of the tolerance compensation member  12  shown in  FIGS. 1 and 2 . Therefore, only the details in which the tolerance compensation member  112  differs from the tolerance compensation member  12  will be described in detail. Details the function of which corresponds to those of details described in conjunction with  FIGS. 1 and 2  are designated with the same reference numerals, respectively increased by 100. 
     The tolerance compensation member  112  has outer and inner support bodies  120 ,  122  configured as helical springs that are wound from spring steel wire. In this case, however, the wire has the cross-sectional shape of a rhomb, i.e. a tipped square with slightly rounded or chamfered corners. The windings of the wire are again in blocking engagement with one another, so that the square cross-sections engage each other only with the chamfered corners. In case of the outer support body  120 , the corners of the squares that face inwardly towards the axis of the helical spring form an internal screw thread (left handed), whereas, in case of the inner support body  122 , the outwardly facing corners of the squares form a complementary external screw thread. 
     In case of the outer support body  120 , the outwardly facing corners of the squares form another external screw thread that is threaded into a complementary internal screw thread of a plastic socket  124 . The socket  124  has claws  126  with which it can be locked at one of the construction members to be connected (not shown here). 
     At the top end in  FIG. 8 , the outer support body  120  is bounded by a terminal plate  128  that is shaped as a metal ring. The terminal plate  128  is a flat, plane-parallel plate and has, on the side facing the support bodies  120  and  122 , two annular concentric grooves  120   a  and  122   a  that are complementary to the respective last turns at the ends of the support bodies  120  and  122 . The depth of the these grooves decreases in circumferential direction from a maximum value that corresponds to the pitch of the helical springs forming the support bodies  120  and  122  continuously to zero, whereby the groove forms a discontinuous step at one position of its periphery, where the depth increases abruptly from zero to the maximum value. In  FIG. 8 , the sectional plane of the drawing has been laid such that it passes through this discontinuity on the right side in  FIG. 8 . Therefore, what is visible here is an end face  120   b  of the wire that forms the top winding of the support body  120 . On the left side in  FIG. 8 , the depth of the groove  120   a  has decreased to one half of the maximum value, so that only the half of the cross-section of the wire that extends beyond the socket  124  is accommodated in the groove  120   a . For the inner groove  122   a  for the inner support body  122  the depth varies correspondingly, but the discontinuity is formed at a position rotated by 180°, i.e. on the left side in  FIG. 8 . What is seen here is the closed end of the groove, because the wire that forms the last turn of the support body  122  ends just in front of the sectional plane of the drawing. In contrast, on the right side in  FIG. 8 , one half of the cross-section of the wire is again accommodated in the groove  122   a.    
     It can further be seen in  FIG. 8  that the respective ends of the grooves  120   a  and  122   a  where their depth is largest pierce the surface of the terminal plate  128 . Therefore, in an end portion that extends over an angular range of 15°, for example, the grooves  120   a  and  122   a  are connected to the top surface of the terminal plate  128  by slots. 
     The terminal plate  128  may be manufactured for example by punching the grooves  120   a  and  122   a  into a disk-shaped blank, with the above-mentioned slots being cut free either before or after the step of punching. In this way, a flat top surface of the terminal plate  128  can be achieved with minimal total thickness of the terminal plate  128 . 
     A second terminal plate  128  that has the same construction and shape as the terminal plate described above is arranged at the bottom end of the support bodies  120  and  122  in  FIG. 8 , but in an inverted position, i.e. with the surface containing the grooves  120   a  and  122   a  facing upwards, and rotated by 90°, so that the sectional plane of the drawing does not pass through the discontinuities of the grooves  120   a  and  122   a  in this case. 
     A plastic sleeve  130  has, in its top end portion, an external screw thread with which it is screwed into the internal screw thread of the inner support body  122 , which screw thread is formed by the wire profile. In the lower end portion, the sleeve  130  has a collar  130   a  with which it is supported on the internal surface of the support body  122 . Optionally, an externally threaded portion may be provided in place of this collar  130   a.    
     In a central portion, between the upper threaded portion and the collar  130   a , the sleeve  130  has a portion with reduced external diameter onto which a spring clip  132  has been snap-fastened. In another embodiment, the spring clip may be formed in one piece with the sleeve. 
     In  FIG. 8 , the sectional plane of the drawing passes through two windows  134  that are formed in the peripheral wall of the sleeve  130  in diametrically opposite positions and that are penetrated by projecting ends  136  of the spring clip  132 , which ends  136  are convexly bulging inwardly. When a connecting bolt, corresponding to the bolt  10  in  FIG. 1 , is inserted through the interior of the sleeve  130 , the ends  136  of the spring clip will come into frictional engagement with the periphery of the connecting bolt. In this way, a slide coupling is formed which, when the bolt is rotated, drives the spring clip  132  and the sleeve  130  and the inner support body  122  connected therewith for joint rotation with the bolt, so that the inner support body  122  is screwed-out of the outer support body  120 . 
     The axial passage formed in the interior of the sleeve  130  for inserting the connecting bolt is flared conically at its top end in  FIG. 8 . Here, the peripheral wall of the sleeve forms a corona of elastic catches  138  that permit to attach the terminal plate  128  from above until the catches  138  snap-in at a collar  140  at the inner periphery of the terminal plate. 
     Above the collar  140 , the inner peripheral surface of the terminal plate  128  forms, at one position of its periphery (on the left side in  FIG. 8 ), a cam  142  that engages in a corresponding recess of the sleeve  130  and thereby prevents the terminal plate  128  from being rotated relative to the sleeve  130 . 
     When, in a step of pre-mounting the device, the inner support body  122  is screwed onto the externally threaded portion of the sleeve  130 , the screwing movement is stopped when the end of the wire forming the support body  122  abuts at the closed end of the groove  122   a . Subsequently, the unit formed of the terminal plate  128 , the sleeve  130  and the inner support body  122  can be screwed into the outer support body  120  that is itself held non-rotatably in the socket  124 . This screwing movement is stopped when the closed end of the groove  120   a  abuts at the end face  120   b  of the wire that forms the outer support body  120 . In this way, the screw-threaded engagement between the two support bodies is prevented from being tightened too strong, so that the frictional force of the slide coupling will be sufficient to cause the inner support body  122  to be screwed-out again. 
     At their outer peripheral edge, each of the terminal plates  128  has a collar  144  which, in case of the bottom terminal plate in  FIG. 8 , serves to snap-fasten this terminal plate in a corresponding recess of the socket  124 . At one location at its outer periphery (on the right side of the top terminal plate in  FIG. 8 ) the terminal plates  128  have another cam  146 . When the terminal plate is used as the bottom end plate, this cam  146  serves to secure the terminal plate  128  non-rotatably in a corresponding recess of the socket  124 . When the inner support body  122  is screwed into the outer support body  120  and a torque (counter clock-wise) is exerted onto the outer support body  120 , the end of the wire that forms the lowermost turn of the body is supported at the closed end of the groove  120   a  in the lower terminal plate. 
       FIG. 9  shows the tolerance compensation member  112  of  FIG. 8  in a sectional view with the plane of the section being rotated by 90°. In this case, the plane of the section passes through the cams  142  and  146  of the lower terminal plate  128 . One of the windows  134  and one of the ends  136  of the spring clip  132  are seen in a front view, whereas the C-shaped bow of the spring clip that straddles the reduced-diameter portion of the sleeve  130  is seen in cross-section. 
       FIG. 10  is a sectional view of the tolerance compensation member in the same sectional plane as in  FIG. 9 , but in a condition in which the inner support body  122  has been screwed-out by one turn. 
     Since the helical springs that form the support bodies  120  and  122  of the tolerance compensation member  112  are subject only to compressive forces when the device is in use and since, further, the individual turns are fixated by the internal screw thread of the socket  124  and, as the case may be, the external screw-threaded portions of the sleeve  130 , it is not compulsory to firmly interconnect the individual turns of the helical springs by gluing or welding.