FR2774016A1 - Spring tensioner for tensioning coil springs of motor vehicles - Google Patents

Abstract

The spring tensioner (1) has a first and second gripper elements (2,3) which are arranged coaxially to each other in a guide tube (8). The two gripper elements can slide relative to each other along the axis of the guide tube by means of an adjuster member.The first gripper element is circular in shape for mounting on the upper spring plate (4). The second gripper element is yoke-shaped and has a winding to engage with the spiral spring. The first gripper element has mounting surfaces which match the contours of the upper spring plate such that during the tensioning process, the upper spring plate has a mounting angle of at least 180 deg. relative to the first gripper element (2,2/1)

Description

Spring compressor for coil springs with a

reduced number of turns.

  The invention relates to a spring compressor for tensioning a helical spring housed under preload between an upper spring disc and a lower spring disc of a suspension strut of the shock absorber spring type for motor vehicles, comprising a first and a '' a second gripping element, arranged coaxially to each other on a guide tube of the spring compressor, and which can be moved relative to each other by means of a tube adjustment member guiding, in the axial direction of the latter, the first gripping element being produced roughly in the form of a circular ring for receiving the spring disc, and the second gripping element being produced in roughly the form of a fork and can be brought into engagement with a coil of the spring

  helical to tension the latter.

  A known spring compressor of the type described (EP 0 349 776 B1), for tensioning springs of axles of motor vehicles in particular, consists of a cylindrical guide tube, in which is housed a rotating threaded spindle, as that adjuster, and two grip elements. The first gripping member is clamped to one end of the guide tube by means of a cylindrical retainer, the gripping member being interchangeably coupled with the retainer via a coupling piece. The second gripping element is interchangeably assembled with a second retaining element by means of a second coupling part, the second retaining element, with the second gripping element, being able to be moved in the axial direction by the regulator, the

  along the guide tube, to tension a helical spring.

  The first gripping element has the shape of a closed ring, L-shaped, which can be placed on the upper side on a spring disc receiving the upper end of the helical spring of a suspension strut. The internal annular surface of the profiled ring, in contact with which the spring disc comes during the tensioning operation, may have several centering steps, so that spring discs of different dimensions

  can be received by the same plug element.

  The second gripping element is roughly in the form of a fork, and also has an L-shaped profile in cross section. The two fork legs of this gripping element form an approximately circular annular element, open opposite the coupling element and having an approximately helical shape. The two gripping elements are arranged on the guide tube so that their central junction axis extends parallel to the longitudinal central axis of the guide tube. A helical spring stretched between the gripping elements is thus also oriented, by its longitudinal median axis, parallel to the guide tube. During the tensioning operation, the second gripping element is first brought into engagement with one of the spring coils in the lower zone of the helical spring, while the first gripping element is simultaneously or previously placed on the upper spring disc. By actuating the threaded pin, the second lower gripping element is moved along the guide tube towards the first gripping element, so that the spacing of these elements is reduced and the spring

  helical is shortened, therefore tense.

  To tension a helical spring with a high pitch, the known spring compressor, with its gripping elements, can however only be used with reservations. On suspension struts which have such high pitch helical springs, on lowered motor vehicles for example, this pitch extends to the extreme turns of the helical spring, so that the upper disc, in particular, of the suspension strut has, to receive the last turn of spring, a peripheral support crosspiece projecting radially outward, roughly adapted to the pitch of the turn in the peripheral direction, at least in partial areas. In the reception zone for the end of the helical spring to be received, the support crosspiece has a corresponding shoulder adapted to the diameter of the spring wire, and which extends approximately perpendicular to the support surface for the coil. formed by the crosspiece. On spring discs made of sheet steel, the upper external side of the disc and / or the support crosspiece

  also such a conformation adapted to the pitch of the spring.

  Since the upper surface, which must be received by the gripping element to tension the helical spring, therefore also has a conformation adapted to the shape of the pitch of the turn, a centered tension of the helical spring is at least rendered difficult, since the planar annular surface of the known gripping member can slip from the spring disc during the tensioning operation. Due to the inclination or the slope of the spring disc, the gripping element can also tilt on the retaining element of the guide tube, since the gripping element cannot be placed flat on the spring disc. Such a tilting leads to a higher stress on the coupling between the retaining element and the coupling part of the gripping element, the risk of rupture of the latter being thereby increased, which leads to a setting endangered service personnel. Due to the high pitch of the spring coils, engaged with the second gripping element to tension the helical spring, such a tilting can also occur on the second gripping element, since the latter has only a reduced slope over the compressor

of known spring.

  The invention therefore aims to produce a spring compressor of the type described so that the tension of helical springs, with a high pitch of the turns, is

safely achievable.

  This objective is achieved, in accordance with the invention, by the fact that the first gripping element has at least one bearing surface adapted to the contour of the upper spring disc so that, during the tensioning operation, the disc upper is applied flat in the grip element,

  at least on a support angle of at least about 180.

  The configuration according to the invention provides a gripping element for a spring compressor in which a spring disk, provided with an ascending bearing surface for a helical spring and an offset in height to receive the end of the coil on the disc side of the coil spring can be received with a centered guide. By the geometrical adaptation at least locally to the contour of the bearing surface of the spring disc, the latter is simultaneously oriented, during tension, approximately transversely to the longitudinal median axis of the helical spring to be tensioned, so an offset or flare of the helical spring in the area between the first and the second gripping element

  is safely avoided during the tensioning operation.

  The geometrical adaptation should be ensured in a peripheral zone of at least 180 approximately, so as to guarantee a centered reception of the spring disc. Depending on the configuration of the latter, it goes without saying that this geometric adaptation can also be ensured over a peripheral zone of more than 180 to 360. If the geometrical adaptation is only ensured over a peripheral zone of approximately 180, the gripping element according to the invention is also also usable for a spring disk whose surface on the external side has a planar configuration, since the zone The latter's residual device also has a planar configuration, and a planar spring disc on the external side is thus guided safely during tensioning. The outer side of the spring disc should be understood to mean the side of the disc opposite a

  helical spring received by the latter.

  In a preferred construction form of the invention, the bearing surface of the first gripping element is a constituent element of the latter. One-piece configuration of the gripper with the bearing surface for the disc

  spring ensures economical manufacturing of this element.

  As an alternative to this configuration, the bearing surface of the first gripping element can also form an integral part of a separate intermediate ring, which can be accommodated with adjustment in the first gripping element, so that an adaptation to different conformations of differently configured spring discs can be achieved in a simple way by replacing intermediate rings of conformations

  differently adapted accordingly.

  Such a possibility of variable use of the first gripping element is also obtained by the fact that several bearing surfaces, of an approximately annular embodiment and of different diameters, are provided, these surfaces having a concentric mutual arrangement and having , in the direction of a longitudinal median axis extending approximately perpendicularly to the bearing surfaces, surfaces of different shapes for adaptation to differently configured spring discs. Since each larger bearing surface forms a peripheral centering shoulder for the neighboring smaller bearing surface, corresponding spring disks are consequently guided and centered on each of the bearing surfaces, high operational safety. being

thereby obtained.

  Since a spring disc with an ascending external contour and offset in height is often used on springs with a high pitch, the operational safety is further increased by the fact that the second gripping element is produced in roughly fork-shaped and has a bearing surface whose slope roughly corresponds to that presented by a coil of spring to be gripped by the second gripping element, in a helical spring stretched between the two discs of a suspension strut, when this leg occupies its maximum unloaded length. This special adaptation of the pitch of the receiving fork of the gripping element excludes any risk of slipping of the captured turn outside the receiving fork, during the integral tension of the helical spring until mutual contact of the individual turns, as during the complete relaxation of a

  helical spring removed from a suspension strut.

  By guiding the spring disc by the first engagement element, the guide tube of the spring compressor is moreover oriented essentially parallel to the received helical spring. On coil springs with a high pitch, the free end of the spring, located outside the gripping elements, would shift laterally during spring tension without adjusting the slope of the second gripping element in the form of fork, so that, when mounting a coil spring of a particularly high pitch, the latter could only be difficultly positioned correctly in the second spring disc of the suspension strut. By adapting the slope of the second gripping element to the pitch of the spring coil to be grasped, which the latter presents when the helical spring is received in an unloaded suspension strut, such lateral offset from the free end of the spring is at least minimized, so that the mounting of the coil spring is considerably facilitated. Furthermore, a tilting of the second gripping element on the retaining element of the guide tube of the spring compressor is also avoided from

sure way.

  The invention will be explained below using the accompanying drawings. Figure 1 is a perspective view of a compressor

  spring with two grip elements.

  Figure 2 is a perspective view of a spring disc of a motor vehicle with an inclined support cross member

  and stepped, with a helical spring.

  Figure 3 is a bottom view of the gripping member

Figure 1.

  Figure 4 is a sectional view along line II - II of

Figure 3.

  FIG. 5 shows a second example of construction of a gripping element according to the invention, with an intermediate ring. Figure 6 is a sectional view along the line IV - IV

in Figure 5.

  Figure 1 shows a spring compressor 1 with a

  first grip element 2 and a second grip element 3.

  The first gripping element 2 has a receiving section 4 produced roughly in the form of a circle ring and provided, as shown in FIG. 4, with a cross section essentially in L. By means of a part coupling 5, the first gripping element 2 is assembled by form locking with a retaining element 6 of the spring compressor 1, arranged with interference fit on the upper end 7 of a guide tube 8 of the vice 1. The second engagement element 3 is provided with a receiving fork 9, also in form-locked engagement with a second retention element 11 of the spring compressor 1, by means of a coupling piece 10 The second retaining element 11 is mounted on the guide tube 8 of the spring compressor 1 with the possibility of axial displacement and without the possibility of rotation. The retaining elements 6 and 11 are oriented so that the receiving section 4 and the receiving fork 11 of the two gripping elements 2 and 3 are coaxially opposite, so that a helical spring 12 to soft, as shown in dashed lines in Figure 1, is received between the gripping elements 2 and 3 extending by its longitudinal median axis 13 parallel to the longitudinal median axis 14 of the guide tube 8. An adjustment pin (not visible in the drawing), arranged inside the guide tube 8, can be driven in rotation by means of a hexagon 15 located axially outside the guide tube 8, for longitudinal movement of the second retaining element 11 with

the second grip element 3.

  The annular receiving section 4 of the first gripping element 2 is placed on a spring disc 16, shown in phantom, of a suspension strut (not shown in the drawing), this disc serving to receive or support the spring helical 12 in the suspension strut. For its attachment to a bodywork of a motor vehicle, the spring disc 16 has four mounting holes 17, regularly distributed around the periphery of a front wall 18 of the disc 16, produced roughly in the form of a circle ring . In its center, the front wall 18 in the form of a ring of the spring disc 16 has a built-in mounting plate 19, provided in its center with a through hole 20. The through hole 20 of the mounting plate 19 is used to receive the piston rod (not shown in the drawing) of a shock absorber of the suspension strut, and can

  be tightened with this piston rod.

  On such a suspension strut, the lowest spring turn 21 in the drawing is received by a second lower spring disc of the suspension strut. In the assembled state of the latter, the helical spring 12 is housed under prestress between the upper spring disc 16 and the lower spring disc of the suspension strut, so that the helical spring 12 has, in this prestressed state, shorter in length than in the unloaded state. To tension the helical spring 12, the receiving fork 9 of the second gripping element 3 is engaged with one of the spring coils 22, as shown by way of example in FIG. 1. By its bearing surface 23 , the receiving fork 9 then has a slope corresponding to the pitch of the turn 22 to the pre-stressed length of the helical spring 12, not that this turn presents when the spring 12 is received in a suspension strut, in the final mounted state, of a motor vehicle, between the upper spring disc 16 and the lower spring disc of the latter, and that

  the suspension strut has its maximum length.

  By this adaptation of the slope of the receiving fork 9, the spring coil 22 is guided on one side in a safe manner during the tensioning operation of the helical spring 12, and also during the relaxation operation, until when withdrawing from the spring compressor 1. Owing to this slope adaptation, only minimal eccentric tension forces occur in particular with respect to the longitudinal median axis 13 of the coil spring 12, so that a tilting of the socket element 3, with its

  coupling part 10, in the retaining element 11 is excluded at least to a large extent.

  As FIG. 1 also shows, the disc of

  spring present in the peripheral zone, axially au-

  below its front wall 18, a peripheral annular wall 24 of an approximately cylindrical embodiment, on the lower extreme edge of which, on the side of the spring, is disposed a receiving crosspiece 25 directed radially outwards and s' extending approximately at right angles to the longitudinal median axis 13. In its configuration, this receiving cross-member 25 is adapted to the pitch or to the shape of the upper turn 26 of the helical spring 12, and has a corresponding inclined shape

in the peripheral direction.

  FIG. 2 is a perspective view of this spring disk 16, the helical spring 12, shown in phantom, being received in plane support by the peripheral receiving cross member 25. For such reception of the upper spring coil 26 by the peripheral crosspiece 25, the latter has a stepped embodiment in the peripheral direction in its front region, the end 28 of the spring being received in the region of the peripheral shoulder 27 shown in FIG. 2. By this stepped embodiment of the cross beam receiving 25, the latter has a support section 29 provided with a slope, this slope being adapted, at least approximately, to that of the upper spring turn5 26. The upper spring turn 26 does not necessarily apply over the entire periphery of the receiving cross member 25, on the lower side of the latter. The receiving section 4 is adapted by its bearing surface

  internal to this conformation of the receiving cross member 25.10 with its slope and its peripheral shoulder 27.

  The gripping element 2 is also shown in bottom view in FIG. 3. FIG. 4 shows a section along the line II - II of FIG. 3 to explain the shape of the bearing surface. FIG. 3 shows the coupling part 5, on one side of the receiving section 4 of the gripping element 2. By being produced essentially in an L shape, the receiving section 4 forms a support ring 30, directed radially inward and delimited in the peripheral direction by an annular wall 31 radially exterior. The lower support surface 32, on the spring side, of the support ring 30 has a support section, provided with a slope with respect to a horizontal plane 34 which extends approximately at right angles with the longitudinal median axis 33 of the receiving section 4. This support section 35 then extends in the peripheral direction approximately over an angle at the center c of about 180. As shown by way of example in FIGS. 3 and 4, the residual bearing surface of the bearing surface 32 can be located in a

  plane 36 parallel to horizontal plane 34.

  The slope of the support section 35 of the support surface 32 corresponds essentially to the slope of the support section 29 of the receiving cross member 25 of the spring disc 16, so that the gripping element 2, by its receiving section 4, can be placed flat on the receiving cross member 25 of the spring disc 16, at least in this zone of the bearing section 35 on the angle at the center a of 180. A central reception of the entire spring disc 16 in the gripping element 2 or in the receiving section 4 of the latter is obtained by this at least local geometric adaptation of the support ring 30, by its surface of support 32, at the conformation of the receiving cross member 25 of the spring disc 16. Furthermore, a centered reception of a spring disc provided with a flat receiving cross member on the upper side is also permitted, since the surface of remaining support of the support ring 30 also has an embodiment

plane.

  It goes without saying that the geometric adaptation of the bearing surface 32 can also relate to an angular range of more than 180, in particular on the peripheral range

  complete with 360 of the support ring 30.

  To receive a spring disc of larger diameter and provided, for example, with a flat receiving cross member, a second bearing surface 37, radially enlarged in diameter and offset in the axial direction, is also provided, the radial delimitation external of this surface being formed by the annular wall 31 of the receiving section 4. As shown in particular in Figure 4, the second bearing surface 37 is made offset in the axial direction relative to the first bearing surface 32, so that its internal radial delimitation forms a centering shoulder 38 for the

first bearing surface 32.

  It goes without saying that the second bearing surface 37 is also adaptable to the contour of a crosspiece receiving a disc.

  spring equipped with a slope and a peripheral shoulder.

  It is also conceivable that, in a configuration similar to that of the second bearing surface 37, other bearing surfaces, of a larger diameter, can also be provided for other discs of

  higher dimension springs.

  Figures 5 and 6 show another example of a 2/1 construction of a first gripping element, which also has a 5/1 coupling piece and a 4/1 receiving section. By its configuration essentially in L, the receiving section 4/1 forms a support ring 30/1, directed radially inward and delimited

  continues by a radially outer annular wall 31/1.

  An interchangeable intermediate ring 39 is accommodated with adjustment in the receiving section 4/1, by the support ring 30/1 and the annular wall 31/1 of the latter, and also has a cross section roughly in L, with a roughly cylindrical annular cross wall 41 and a continuous support ring 40, directed radially inwards. The support ring 40 is provided with a lower support surface 32/1, on the side of the spring, which has a support section 35/1. The support section / 1 is provided with a slope with respect to a horizontal plane 34/1 which extends approximately at right angles to the longitudinal median axis 33/1 of the receiving section 4/1. This support section 35/1 then extends in the peripheral direction approximately over an angle at the center a of about 180. As shown by way of example in FIGS. 5 and 6, the residual bearing surface of the bearing surface 32/1 can be

  locate in a plane 36/1 parallel to the horizontal plane 34/1.

  The gripping element 2/1 of the example of construction of FIGS. 5 and 6 therefore differs from the gripping element 2 of FIGS. 2 and 3 only by the intermediate ring 39, provided with the bearing surface 32 / 1 geometrically adapted to receive the spring disk 16. The configuration of the bearing surface

  32/1 corresponds to that of the bearing surface 32, and consequently has the same advantages.

  To receive a spring disc of larger diameter and provided, for example, with a flat receiving cross member, a second bearing surface 37/1, with a diameter also widened in the radial direction and offset in the axial direction , is also provided, its radially outer delimitation being formed by the annular cross wall 41. The second bearing surface 37/1 is also made offset in the axial direction relative to the first bearing surface 32/1 , so that its radially inner delimitation forms a centering shoulder 38/1 for the first bearing surface

32/1.

  It goes without saying that this second bearing surface 37/1 is also adaptable to the contour of a cross member for receiving a spring disc provided with a slope and a peripheral shoulder. It is also conceivable that, in a configuration analogous to that of the second bearing surface 37/1, other bearing surfaces, of a larger diameter, can be further provided for

  other larger spring discs.

  The configuration according to the invention of the two gripping elements 2, 2/1 and 3 provides a spring compressor which makes it possible to tension helical springs at a high pitch, without risk of offset or flaring of the spring during the tension operation, in the area between the two

gripping elements 2, 2/1 and 3.

  This is due, on the one hand, to the geometrically adapted configuration of the support surface 32, 32/1 of the support ring 30 or of the support ring 40 of the gripping element 2 or 2 / 1, supplemented by adapting the slope of the receiving fork 9 of the gripping element 3 to that of a helical spring 12 mounted between two spring discs, when the latter is housed in a suspension strut not loaded, i.e. not axially shortened. By adapting the slope of the receiving fork 9 of the second gripping element 3, a lateral offset from the lower end 21 of the helical spring 12 is also largely avoided so that the latter, during assembly, can be easily aligned with the lower disc of the strut, and be

  received by the latter with correct orientation.

Claims (5)

Claims.   1. Spring compressor for tensioning a helical spring housed under prestress between an upper spring disc and a lower spring disc of a suspension strut of the spring-shock absorber type of motor vehicles, composed of a first and a second gripping element, arranged coaxially to one another on a guide tube of the spring compressor, and which can be moved relative to each other by means of a guide tube adjustment member, in the axial direction of the latter, the first gripping element being produced more or less in the form of a circle ring for receiving the spring disc, and the second gripping element being produced more or less in the form of a fork and which can be brought engaged with a coil of the helical spring to tension the latter, characterized in that the first engagement element (2, 2/1) has at least one bearing surface (32, 32/1) adapted to the contour of the disc upper spring ( 16) so that, during the tensioning operation, the upper disc (16) is applied flat in the gripping element (2, 2/1), at   less on a support angle of at least about 180.   2. Spring compressor according to claim 1, characterized in that the bearing surface (32) of the first engagement element (2) is a component of a single part of the gripping element (2).   3. Spring compressor according to claim 1, characterized in that the bearing surface (32/1) of the first engagement element (2/1) is a component of a separate intermediate ring (39), which can to be accommodated with   adjustment in the first gripping element (2/1).   4. Spring compressor according to one of claims 1   to 3, characterized in that several bearing surfaces (32, 37 or 32/1, 37/1), of an approximately annular embodiment and of different diameters, are provided, these surfaces having a concentric mutual arrangement and having, in the direction of a longitudinal median axis (33, 33/1) extending approximately perpendicular to the bearing surfaces (32, 37 or 32/1, 37/1), surfaces of different shapes for the adaptation to spring disks (16) differently configured, and in that each larger bearing surface (37, 37/1) forms a peripheral centering shoulder (38, 38/1) for the bearing surface smallest neighbor (32, 32/1).   5. Spring compressor according to one of claims 1   4, characterized in that the second gripping element (3) is roughly in the form of a fork and has a slope which roughly corresponds to that presented by a spring coil (22) to be grasped by the second element grip (3), in a helical spring (12) stretched between the two discs (16) of a suspension strut, when this   leg occupies its maximum unloaded length.