DE20019720U1 - Spring tensioner for tensioning unstable or bent pre-tensioned coil springs - Google Patents

Description

.„ NEYMEYER & PARTNER GBR, Patent Attorneys · 1*1 * * i JJ 78J52 Villingen-Schwenningen (DE)

^ ₁ MN/mn ....··· ....·. ...» November 17, 2000

Applicant ref.: K 255

Applicant: Klann Tools Ltd., 13 Harrier Park, Didcot, Oxfordshire, 0X11 7PL, GB

Applicant No.: 8635978

Description.· Spring tensioner for tensioning unstable or bent pre-tensioned coil springs

Description

The invention relates to a spring tensioner for tensioning coil springs, consisting of a tensioning device on which two tensioning elements are arranged, which are provided with gripping elements for receiving the coil spring to be tensioned, wherein the distance between the tensioning elements for tensioning and relieving the coil spring can be changed by actuating the tensioning device.

Spring tensioners of the generic type are well known, for example from DE-PS 28 13 381 or from German utility model G 94 04 430.9.

Such spring tensioners essentially consist of a tensioning device on which two tensioning elements are arranged. The tensioning device has a guide tube in which a threaded spindle is provided, which has a drive hexagon that protrudes axially from the guide tube to operate the tensioning device. The tensioning elements each have a short, approximately tubular coupling for mounting on the guide tube of the tensioning device.

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NEYMEYER & PARTNER GbR, Patent Attorneys _&bgr; · J· · J · JJJ 78552 Vülingen-Schwenningen (DE) MN/mn ·* 17 November 2000

element, whereby the first clamping element with its coupling element is arranged so as to be firmly seated at the end of the guide tube opposite the drive hexagon. The second clamping element, on the other hand, is guided with its coupling element on the guide tube so that it can be moved and cannot be rotated.

An actuating cylinder with an internal thread is provided on the threaded spindle, to which the coupling element of the second, movable clamping element is connected.

By rotating the threaded spindle, the actuating cylinder is moved together with the second clamping element in the axial direction of the guide tube. This means that when the clamping device is operated by rotating the threaded spindle, the distance between the two clamping elements is changed by moving the second clamping element along the clamping device.

When tensioning a coil spring that is to be tensioned, the distance between the two tensioning elements is reduced by operating the tensioning device, so that the coil spring held in the gripper elements of these tensioning elements is compressed. If the threaded spindle rotates in the opposite direction, however, the distance between the tensioning elements and their gripper elements increases, so that a clamped coil spring is relieved or completely relaxed.

K255.doc · · ·

NEYMEYER & PARTNER GbR, Patent Attorneys « J · J t * * « * ⁷⁹ &psgr; ² VUlingen-Schwenningen (DE) MN/mn ···· ··· * ^## '* 17 November 2000

Different types of connection are provided for coupling the gripper elements, which can be designed as separate components, with the coupling elements, the exact design of which will not be discussed in detail here. In this respect, reference is made to the sources given. It should be noted that a one-piece design of the gripper elements with the pipe segments can also be provided, as is known, for example, from DE 196 31 524 Cl.

What all these spring tensioners and their tensioning elements have in common is that the gripping elements are arranged coaxially to one another and at the same radial distance from the tensioning device. Furthermore, the gripping elements, which in the known spring tensioners are U-shaped, for example, have a certain incline in their circumferential direction. This enables a more favorable reception of a spring coil of a coil spring to be tensioned. Due to the helical course of the U-legs of these U-shaped gripping elements, they are arranged essentially symmetrically with respect to a transverse plane running transversely to the longitudinal center axis of the tensioning device. This is intended to ensure that a coil spring held between the two gripping elements by tensioning elements designed in this way is guided in a straight line during the tensioning process as well as during the release process. This means that with the same radial distance

NEYMEYER & PARTNER GbR, Patent Attorneys · · ■» · · &psgr; JJ · 78^52 ViUingen-Schwenningen (DE) MN/mn ^# * "'* 17 November 2000

position of the gripper elements of the clamping elements and coaxial alignment of the clamping elements or their gripper elements to each other, the helical spring accommodated between the gripper elements is aligned and guided with its longitudinal center axis essentially parallel to the longitudinal center axis of the clamping device. To securely accommodate a spring coil in the respective gripper element, the gripper elements have an approximately L-shaped cross section and form a safety web along the outer edge of their support surfaces for the respective spring coil. Furthermore, a further retaining web is provided between the U-legs of the gripper elements in the area of the inner edge of the gripper elements, which is intended to prevent slipping out of the fork shape of the gripper elements which is open on one side.

It has now been shown that, particularly when tensioning unstable coil springs, they tend to "bulge" between the gripper elements during the tensioning process. By "bulging" we mean that the coils of the coil spring, which are clamped between the two gripper elements, move radially to the side in relation to the longitudinal center axis of the coil spring, so that the straight, essentially cylindrical shape of the coil spring changes into an arcuately curved shape.

If the "bulge" of the clamping device points in the direction of the open fork shape of the gripper elements, this can again

Neymeyer & Partner GbR, Patent Attorneys MN/mn

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This can cause such an unstable coil spring to slip out of the gripper elements, as the spring coils accommodated in the gripper elements also tend to follow this "bulge" and can therefore assume an inclined position in relation to the gripper elements. Due to this tendency for the accommodated spring coils to be inclined, in unfavorable cases they can slide up on the inner retaining web, so that they can slip out of the respective gripper element.

Furthermore, the tensioning of a bent pre-tensioned coil spring is only possible to a limited extent with the known spring tensioners, since the tensioning elements with their gripping elements can only be brought into engagement with this bent coil spring with difficulty or not at all. In particular with coil springs that are pre-tensioned with a stronger bend, as can be the case with motor vehicle axles, for example, it is almost impossible to grasp a coil spring that is bent in this way with the gripping elements known from the prior art, especially when the distances between the spring coils are small.

Accordingly, the invention is based on the object of designing a spring tensioner for tensioning coil springs, which is provided in particular with two tensioning elements with gripping elements, in such a way that a secure tensioning of unstable, lateral

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NEYMEYER& PARTNER GbR, Patent Attorneys .· ' ·· * J*t j J780S2 Viüingen-Schwenningen (DE) MN/mn ··*· *·· ··· *·* " " November 17, 2000

It is possible to safely carry out the test on coil springs that tend to deflect and also on bent pre-tensioned coil springs.

The object is achieved according to the invention in that the gripper elements are arranged obliquely, converging towards one another, starting from the clamping device, in a transverse plane arranged substantially at right angles to the longitudinal center axis of the clamping device.

The design according to the invention makes it possible to safely tension unstable coil springs, for example. For this purpose, the gripper elements are arranged at an angle to a transverse plane that is essentially at right angles to the longitudinal center axis of the tensioning device, starting from the tensioning device, and converging towards one another. This means that the gripper elements are arranged at an angle, for example in relation to the coupling element with which the tensioning elements are mounted on the tensioning device. This angled arrangement ensures that when tensioning an unstable coil spring, the spring coils lying between the tensioning elements or gripper elements are always bent at least slightly in the direction of the tensioning device. This predetermined, targeted "bulging" of the coil spring between the gripper elements reliably prevents the coil spring from slipping out of the gripper elements. In particular,

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NEYMEYER & PARTNER GbR, Patent Attorneys _»* ·· * * * &iacgr;&iacgr; J ⁷⁸⁰ f ² Vailngen-Schwenningen (DE) MN/mn ·· ··· ··· ·· ** 17 November 2000

a "bulge", for example, in the opposite direction, i.e. with a curvature directed outwards from the clamping device, is definitely excluded. Because with such an outward "bulge" there is always the danger, as already explained above with regard to the state of the art, that the helical spring clamped between the gripper elements with the spring coils accommodated in the respective gripper elements can slip out of these gripper elements due to the curvature as the clamping path increases. However, since the essentially U-shaped gripper elements form a safety web towards the clamping device that extends at least almost completely along the outer edge of the respective gripper element due to their L-shaped cross section, a helical spring pre-curved towards the clamping device cannot slip out of the gripper elements of the clamping elements in this direction.

Furthermore, the design according to the invention also makes it considerably easier to attach a spring tensioner with the tensioning elements according to the invention to a slightly bent pre-tensioned coil spring or even possible for a more strongly bent pre-tensioned coil spring. Due to the intended inclination of the gripping elements, they can be easily inserted between two spring coils of a bent pre-tensioned coil spring, the spring

K255.doc

NEYMEYER & PARTNER GbR, Patent Attorneys ·' · · * · · £ · »78062 VUlingen-Schwenningen (DE) MN/mn ···· *** ·*· ··· ·· ·* November 17, 2000

windings also have an equal or greater angle of inclination to the transverse plane of the tensioning device when the tensioning device is attached.

In order to prevent the "bulge" of an unstable coil spring to be tensioned in the direction of the tensioning device from becoming too large, the angle of inclination (al, a2) of the respective gripper element to the transverse plane can be approximately 4° to 10° according to claim 2. This ensures, on the one hand, that a "bulge" in the direction of the tensioning device occurs reliably when tensioning an unstable coil spring and, on the other hand, that the curvature of this coil spring to be tensioned does not become too large.

If, however, the spring tensioner according to the invention with its tensioning elements according to the invention is to be used to tension a bent pre-tensioned coil spring, the angle of inclination (al, a2) according to claim 3 is preferably adapted to the angle of attack (ßl, ß2) of the respective spring coil of the coil spring to be gripped. Such bent pre-tensioned coil springs are frequently encountered in particular in the axle constructions of motor vehicles. The corresponding coil spring is located between two spring plates of the axle construction, with these spring plates in turn being arranged at an angle to one another. This inclined arrangement of the spring plates to-

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NEYMEYER & PARTNER GbR, Patent Attorneys · · * * · » * * »78062 Villingen-Schwenningen (DE)

MN/mn ··*· ··· ··· ··· ·· ·* November 17, 2000

The curved pre-stressed course of the coil spring is achieved when installed on the vehicle.

According to the invention, according to claim 3, the angle of inclination (al, a2) is smaller than or at most equal to the angle of attack (ßl, ß2) of the respective spring coil of the helical spring to be gripped to a transverse plane running at right angles to the longitudinal center axis of the tensioning device of a spring tensioner properly attached to the helical spring. This means that the angle of inclination (al, a2) of the gripper elements should be at most equal to the angle of attack (ßl, ß2) of the respective spring coil to be gripped. By choosing the angle of inclination (al, a2) of the gripper element in adaptation to the angle of attack (ßl, ß2) of the respective spring coil to be gripped, the attachment of the spring tensioner is made considerably easier for slightly bent helical springs during tensioning and is only made possible for more strongly bent helical springs, since the gripper elements which run at an angle in this way can be easily inserted into the likewise inclined spring coils of a bent pre-tensioned helical spring. In the case of a slightly bent preloaded coil spring with a smaller radius of curvature, the angle of inclination (al, a2) can be equal to the angle of attack (ßl, ß2)

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Neymeyer & Partner GbR, Patent Attorneys ^** ·» * J * 1 · ·78&thgr;|2 VUüngen-Schweniiingen (DE) MN/mn ·· *· *·· *· ·*' 17 November 2000

correspond to the spring coil of the coil spring to be accommodated.

If the bent pre-tensioned coil spring has a greater curvature, the angle of inclination (al, a2) is preferably selected to be smaller than the angle of attack (ßl, ß2). The spring tensioner can still be easily brought into engagement with the bent pre-tensioned coil spring. Due to the different angles of the gripper element and the spring coil, the bent pre-tensioned coil spring is initially straightened slightly during the tensioning process, as it inevitably adapts to the inclination of the gripper elements via the spring coils it accommodates. The smaller angle of inclination (al, a2) compared to a relatively large angle of attack (ßl, ß2) also enables the coil spring to be completely relaxed without the gripper elements in the coil spring becoming jammed due to the straight alignment of the coil spring during relaxation. After the coil spring has been completely relaxed, the gripper elements can therefore be removed from the now completely straight, relaxed coil spring. When installing the coil spring, it is always pre-bent at least slightly, so that its insertion between two spring plates of a motor vehicle axle arranged at an angle to each other is made considerably easier.

NEYMEYER & PARTNER GbR, patent attorneys · · * * t * $ * j78062 Villingen-Schwenningen (DE) MN/mn ··*· *** *** ·** ·* ·* November 17, 2000

The inventive design of the gripper elements advantageously ensures that the helical spring is pre-bent for installation between these spring plates during the tensioning process and in its tensioned final state already assumes the bent installation shape or is at least brought so close to the bent installation shape that when the helical spring is subsequently relieved, it is securely received with its end turns in the spring plates without there being any danger of it slipping out.

In order to ensure that the tensioning device is not damaged if the "bulge" becomes too large, in particular if the coil spring is unstable, the tensioning device has a protective cover in the area between the tensioning elements that faces the coil spring to be accommodated, according to claim 4. This means that a coil spring that "bulges" too much cannot come into direct contact with the tensioning device.

If such a protective cover is not necessary, which may be the case when tensioning a bent pre-tensioned coil spring with a slight curvature, this protective cover is attached to the tensioning device via a snap-in or clamp connection in accordance with claim 5. This means that the protective cover can be easily removed or replaced in the event of any damage.

NEYMEYER & PARTNER GbR, Patent Attorneys · * ·» · «·»! 5?8052 VUUngen-Schweiuiingen (DE) MN/mn ··*· ··· ·♦· ··· ·· ·· November 17, 2000

If the protective cover is damaged, it can be easily removed and replaced with a new protective cover.

According to claim 6, the axial position of the protective cover on the tensioning device between the tensioning elements is variably adjustable. This means that the protective cover can be easily moved along the tensioning device between the two tensioning elements. This means that the position or axial position of the protective cover can be adapted to the length of a coil spring to be tensioned and can essentially always be set up in such a way that the protective cover can always be arranged in the axial area of the "bulging" coil spring.

According to claim 7, the gripper elements are designed to be fork-shaped or U-shaped and have an approximately L-shaped cross-section, as is already known from the prior art. Due to this L-shaped cross-section, the gripper elements form a support section on which the coil springs to be tensioned rest with their gripped spring coils and, on the other hand, an outer safety web so that the coil springs cannot accidentally slip out of the gripper elements. According to the invention, according to claim 7, the support section in the end region of the two U-legs of the gripper element is designed to be longer than the circumferential safety web so that this support section

NEYMEYER & PARTNER GbR, Patent Attorneys MN/mn

• j78OS2 VUlingen-Schwenningen (DE) 17 November 2000

te protrude beyond the safety web. In other words, the safety webs at the end area of the respective U-legs of the gripper element are designed to be shorter than the support sections. This design makes it considerably easier to attach the spring tensioner with the gripper elements according to the invention, in particular to a bent pre-tensioned helical spring.

According to claim 8, the support section of the respective U-leg of a gripper element can have a recess or notch in its end region projecting beyond the safety web in extension to the safety web. This means that this end region is designed to be reduced in its support width in the region of its radial outer edge. This design reliably prevents the gripper element from colliding with body components located in the immediate vicinity of the coil spring when it is placed on a coil spring installed in a vehicle axle.

According to claim 9, the gripper elements can be designed in their circumferential length in such a way that the spring coils of a coil spring to be tensioned rest on the respective gripper element over an angle of up to approximately 24 0°, at least in the slightly pre-tensioned state of the coil spring.

K255.doc

NeyMEYER & PARTNER GbR, Patent Attorneys MN/mn

.* I * &idigr; !·*! isoil VilUngen-Schwenningen (DE) .... ... .»· ··» .« .. 17 November 2000

This ensures that the coil spring held between the gripper elements, which are inclined to one another, is also safely brought into its desired curved position. The large support angle of up to 240° ensures a corresponding forced guidance for the respective spring coil, so that it safely assumes the angle of inclination of the respective gripper element when the coil spring is tensioned.

An embodiment of the invention is explained in more detail below with reference to the drawing. It shows:

Fig. l is a partial longitudinal section of a spring tensioner with an embodiment of two tensioning elements according to the invention;

Fig. 2 is a partial section II-II of the lower clamping element of the spring tensioner from Fig. 1;

Fig. 2a shows a partial section of a clamping element with a shortened safety bar;

Fig. 2b is a plan view of the U-leg of an embodiment of a gripper element from Fig. 2a;

Fig. 3 shows an embodiment of a labile coil spring;

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Fig. 4 shows the spring tensioner from Fig. 1 in a state attached to the coil spring from Fig. 3, whereby this coil spring is already slightly pre-tensioned and the tensioning device is provided with an additional protective cover;

Fig. 4a shows a partial section IV-IV of Fig. 4;

Fig. 5 a tensioning device together with a bent pre-tensioned coil spring of a motor vehicle axle, with gripping elements adapted to the curved course of the coil spring;

Fig. 6 shows the spring tensioner from Fig. 5 when attached to the coil spring from Fig. 5;

Fig. 7 shows the spring tensioner from Fig. 5 and 6 with the coil spring fully compressed.

Fig. 1 shows a partial longitudinal section of a spring tensioner 1, which has a tensioning device 3 for tensioning a coil spring 2 shown as an example in Fig. 3, on which two tensioning elements 4 and 5 are arranged. The basic structure of this spring tensioner 1 shown as an example corresponds essentially to the spring tensioner known from the prior art of DE 196 31 524.7.

NEYMEYER & PARTNER GbR, Patent Attorneys MN/mn

." I , I ! · * ! ?8&thgr;4 Villingen-Schwenningen (DE) .... ... ·«* ··· ,4 .. 17 November 2000

Thus, the clamping device 3 has two retaining webs 7 and 8 at its upper end 6, by means of which the upper clamping element 4 is held axially firmly on the clamping device 3 via a corresponding, approximately tubular coupling element 9. The connection between the coupling element 9 and the retaining webs 7 and 8 at the upper end 6 of the clamping device 3 is designed, for example, as a type of bayonet lock, as is already known from the prior art specified in DE 196 31 524.7.

The lower, second clamping element 5 is also provided with an approximately tubular coupling element 10, with which the clamping element 5 is guided axially displaceably on the clamping device 3. For this purpose, the clamping device 3 has a guide tube 11, along which the clamping element 5 with its coupling element 10 can be axially displaced. To adjust the axial distance between the two clamping elements 4 and 5, a threaded spindle 12 is provided in the guide tube 11, on which an actuating cylinder 13 with an internal thread is accommodated in an axially adjustable manner. This actuating cylinder 13 is adapted to the internal dimensions of the guide tube 11 in such a way that it can be accommodated in the guide tube II with a small amount of play so that it can be axially displaced.

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NEYMEYER & PARTNER GbR, patent attorneys . * ·· ! · · * · *80i Villingen-Schwenningen (DE)

MN/mn ···· ··· ··· ··· ·* ·♦ November 17, 2000

The threaded spindle 12 is in turn axially fixed and rotatably mounted in the two end regions of the guide tube II via two axial thrust bearings 14 and 15.

It is easy to imagine that when the threaded spindle 12 is actuated via the drive hexagon 16 provided at the lower end, the actuating cylinder 13 executes an axial movement relative to the guide tube II. The actuating cylinder 13 is provided with a coupling finger 17 which projects radially through the guide tube 11 for the positive coupling with the coupling element 10 of the clamping element 5. This coupling finger 17 is guided axially displaceably and non-rotatably in an adjusting slot 18 of the guide tube 11 which is open at the bottom. Due to the positive coupling of the clamping element 5 via its coupling element 10 with the coupling finger 17 of the actuating cylinder 13, the clamping element 5 is thus axially adjusted when the threaded spindle 12 is actuated, so that the distance between the clamping element 5 and the clamping element 4 changes in order to tension or relieve a coil spring accommodated in the clamping elements 4 and 5.

In order to accommodate the helical spring 2 shown as an example in Fig. 3, the two tensioning elements 4 and 5 are each provided with gripper elements 19 and 20 which, in the present embodiment, are approximately U-shaped.

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MN/mn ···· ··· ·♦· ··· ·· ·· November 17, 2000

These gripper elements 19 and 20 are each arranged at an inclination angle of α or α2 with respect to a transverse plane 22 or 23 running transversely to the longitudinal center axis 21 of the clamping device 3. The arrangement is selected such that the two gripper elements 19 and 20 converge towards one another starting from the clamping device 3, as can be seen in Fig. 1. This means that on the one hand the two U-legs 24 and 25 of the gripper element 19 and the two U-legs 26 and 27 of the gripper element 20 are arranged asymmetrically to the respective transverse plane 22 or 23. Furthermore, the radial distance of the two gripper elements 19 and 20 from the clamping device 3 is identical in the present embodiment, so that the gripper elements 19, 20 lie on a common "longitudinal center axis" 28.

The U-shaped design of the two gripper elements 19 and 20 is shown in particular in the top view of Fig. 2 for the lower gripper element 20. From the representations in Figs. 1 and 2 it can be seen that the gripper elements essentially have an L-shaped cross section. This means that the two gripper elements 19 and 20 form a U-shaped support surface 29 and 30, respectively, which are each limited in the area of their outer edge by a safety web 31 and 32, respectively. As a further safeguard for a spring coil accommodated in the respective gripper element 19 and 20, in the area of the inner edge

NEYMEYER & PARTNER GbR, Patent Attorneys ** ·· « *»· · *80 5 Villingen-Schwenningen (DE)

MN/mn ···· ··· ··· ··· *··* ··* November 17, 2000

A further retaining web 33 or 34 is provided on the support surface 29 or 30 between the respective IT legs 24 and 25 or 26 and 27, by means of which the spring coil held in each case is reliably prevented from slipping out of the U- or fork shape of the gripper elements 19, 20, which is open on one side, under normal operating conditions. In the embodiment of the two gripper elements 19 and 20, the safety webs 33 and 32 have the same "circumferential length" as the corresponding U-legs 24, 25 or 26, 27 or the associated support surfaces 29 or 30.

In order to make it easier to attach the spring tensioner l to a coil spring, in particular to a bent pre-tensioned coil spring, and to tension this coil spring, the safety webs 31 and 32 can also be designed to be shorter than the associated U-legs. Such a design is shown as an example in Fig. 2a for the gripper element 20/1 of a tensioning element 5/1. It is clearly visible that the safety web 32/1 is designed to be significantly shorter than the common support surface 30/1 of the two U-legs 26/1, 27/1 of the gripper element 20/1. Such a shorter design of the safety web 32/1 can be particularly advantageous if the free ends of the U-legs 26/1 and 27/1 do not run parallel to one another in a straight line, as shown in Fig. 2 for the U-legs 26 and 27.

NEYMEYER & PARTNER GbR, patent attorneys . * I . I !·· I ?8&thgr;&phgr; Vülingen-Schweiuiingen (DE)

MN/mn ··»· ··· ·&iacgr;· ·&iacgr;· *··**.»* November 17, 2000

but are circularly arc-shaped, particularly in the region of their outer edge, as indicated in Fig. 2 by the dashed lines in the outer end region of the U-legs 26 and 27.

Furthermore, the U-legs 26/1 and 27/1 can be provided with a recess or notch 27' in the extension of the shorter safety web 32/1 in the region of their radially outer edge, as shown for the U-leg 27/1 in Fig. 2b.

It can be seen that the support surface 30/1 of the U-leg 27/1 is therefore smaller in width in the end area which adjoins the safety web 32/1. This design allows a spring tensioner to be attached to bent pre-tensioned coil springs where there are body components in the immediate vicinity of the coil spring without a collision with these parts occurring.

The coil spring 2 shown in Fig. 3 is shown in its relaxed initial state and runs in a straight line with its longitudinal center axis 35. Furthermore, it is shown by way of example using the two spring coils 36 and 37 that these spring coils 36 and 37 in this relaxed initial state of the coil spring 2 have no angle of inclination with respect to a transverse plane 38 or 39 running transversely to the longitudinal center axis 35.

NEYMEYER & PARTNER GbR, patent attorneys ,* · . i *··· j805j Villingen-Schwenningen (DE) MN/mn ·»»» ·»■ ··· «I* *i«"**e November 17, 2000

This means that the two spring coils 3 6 and 3 7 with their two partial coils 40 and 41 or 42 and 43 are arranged symmetrically to the respective associated transverse plane 38 or 39.

The coil spring 2 shown in Fig. 2 has a relatively thin wire cross-section, so that this coil spring 2 is relatively unstable. Such an unstable coil spring 2 tends to automatically "bulge" radially outwards in the direction of arrow 44 (Fig. 1) during the tensioning process, as already explained at the beginning of the prior art, when tensioned in a straight line using a previously known spring tensioner, as is shown by the curved center line 45 in Fig. 1.

As can easily be imagined, such a "bulging" of an unstable coil spring held between two gripping elements of a conventional spring tensioner creates the risk that the coil spring, for example with its spring coils 36 and 37, can slip over the corresponding inner retaining web of such a conventional gripping element, so that a sudden relaxation of the coil spring can occur.

In order to reliably prevent such bulging of the coil spring 2 in the direction indicated by the arrow 44, the two gripper elements 19 and 20 are

NEYMEYER & PARTNER GbR, patent attorneys , * J . &zgr; · · i J .{80$ Vfflingen-Schwenningen (DE)

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According to the invention, they are arranged at an angle of inclination a1 or a2, converging towards one another. Due to this inclined arrangement of the two gripper elements 19 and 20, the helical spring 2 is bent in the opposite direction of arrow 44 in Fig. 1 during the tensioning process and is "forced" to bend, as shown in Fig. 4 by arrow 46.

Furthermore, it can be clearly seen from Fig. 4 that the helical spring 2, due to its pre-tension between the two gripper elements 19 and 20, with its two spring coils 36 and 37, is brought into a corresponding inclined position to the respective transverse plane 22 or 23 by the same angle a1 or a2 of the respective gripper element 19 or 20. This results in the pre-bent course of the helical spring 2 shown in Fig. 4, the curvature of which is illustrated by the curved center line 35 of the helical spring 2 in Fig. 4. This predetermined curved course of the helical spring 2, directed towards the tensioning device 3, reliably prevents the helical spring 2 with its spring coils 36 and 37 from slipping out of the gripper elements 19 and 20. Due to this oblique course of the gripper elements 19 and 20, the spring coils 36 and 37 are automatically held securely in the respective gripper element 19 and 20 due to the angle of inclination a1 and a2, respectively. In the present embodiment of the spring clamp

NeymEYER & PARTNER GbR, Patent Attorneys MN/mn

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ners from Fig. 1 to 4, the inclination angle a1 and also the inclination angle ct2 of the two gripper elements 19 and 20 are each 6° to the respective transverse plane 22 and 23. It is also clearly visible from Fig. 1 and 4 that the two transverse planes 22 and 23 run parallel to one another.

It should be noted here that the two angles of inclination a1 and a2 do not necessarily have to be the same. They can also take on different values, especially if a coil spring to be tensioned is made from a spring wire whose diameter changes over the length of the coil spring, as can be the case with progressive springs, for example.

From Fig. 4 it can also be seen that a protective cover 64 is arranged on the guide tube 11 of the tensioning device 3. This protective cover 64 serves to protect the guide tube II or the tensioning device 3 in the event that the "bulging" of the coil spring 2 is so large that contact with the guide tube II by the coil spring 2 cannot be ruled out. Such further bulging of the coil spring 2 beyond the curvature actually intended, predetermined by the inclination of the gripper elements 19 and 20, can occur, for example, with extremely unstable coil springs. The protective cover 64 is used in the present embodiment.

K255.doc

Neymeyer & Partner GbR, Patent Attorneys MN/mn

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• 78OSJ ViUinfien-**wejningen (DE)

17.Sovember 2000

play is formed from a wall section 65 oriented towards the coil spring 2 which is replaceably attached to the guide tube II by means of second retaining clips 66 and 67. These retaining clips 66, 67 thus act as a type of snap-in connection to the guide tube II. This means that the protective cover 64 can be easily removed when it is not needed. On the other hand, the protective cover 64 can also be easily replaced or renewed if it is damaged. Furthermore, the protective cover 64 can be moved axially on the guide tube II so that it can always be arranged in the area of the maximum bulge of the coil spring 2 and, on the other hand, can also be moved axially upwards during the tensioning process by the lower tensioning element 5 which moves upwards. The axial length of the protective cover 64 is selected such that the maximum tensioning stroke required to tension the coil spring 2 can always be carried out.

In order to prevent accidental rotation of the protective cover 64 or the wall section 65 on the guide tube II, it is provided with a radially inwardly directed guide web 68 which engages in the guide slot 18 of the guide tube II in an axially displaceable manner. As can be seen from Fig. 4, the protective cover 65 is relatively short and can be positioned axially as desired between the two clamping elements 4 and 5.

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Neymeyer & Partner GbR, Patent Attorneys MN/mn

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In this way, the protective cover can be positioned exactly in the middle between the clamping elements 4 and 5 at the start of the clamping process. As the clamping path increases, the lower clamping element 5 moves upwards and, from a certain clamping stroke, takes the protective cover 65 with it. Furthermore, the cover can also serve as additional guide for the coil spring 2 to be clamped. For this purpose, as can be seen in particular from Fig. 4a, two guide walls 69 and 70 are provided at the sides. These guide walls 69, 70 extend in the direction of the gripper elements 19, 20 and hold the coil spring 2 (shown in phantom lines in Fig. 4a) between them, particularly in its bulged area. This reliably prevents the coil spring 2 from deflecting sideways approximately at right angles to the plane of curvature 71 (Fig. 4a). From Fig. 4a it can also be seen that the circumferential length and the radial width of the gripper element 20 are so large that the coil spring 2 shown in phantom lines is gripped by the gripper element 20 over a support angle of approximately 240°. This ensures a positive guidance of the received spring winding 37 (Fig. 4) in such a way that it assumes the inclined orientation of the gripper element 20 at the beginning of the clamping process, as can be clearly seen from Fig. 4. Furthermore, this "large-area" support of the spring winding 37 in the gripper element 20 or the

K255.doc

Neymeyer & Partner GbR, Patent Attorneys MN/mn

: 780<& ViUiit-eniimeliningen (DE) ·.. ... »· 17«November 2000

Spring winding 36 in the gripper element 19 and the forced guidance caused thereby reliably prevent the spring windings 36, 37 from slipping out of the respective gripper element 19 or 20, since the spring windings 36, 37 cannot lift off the respective support surface 29 or 30 of the gripper element 19 or 20, particularly in the area of the holding webs 33, 34 (Fig. 1).

Fig. 5 shows a further embodiment of a spring tensioner l/l, which is essentially identical to the spring tensioner l from the previous drawing figures 1 and 4. The design of the inclination angles a1 and a2 in the spring tensioner l/l differs from the embodiment according to Figs. 1 and 4. In the embodiment of the spring tensioner l/l according to Fig.

5, the two gripper elements 19/2 and 2 0/2 of the two clamping elements 4/2 and 5/2 each have a larger angle of inclination a1 and a2 to the respective transverse plane 22 and 23, respectively.

In the case of the embodiment according to Fig. 5, the two angles of inclination a1 and a2 are approximately 8° to the respective transverse plane 22 and 23, respectively. Such a larger angle of inclination a1 or a2 may be necessary in order to securely tension a bent pre-tensioned helical spring 50 or to be able to attach the gripper elements 19/2 and 20/2 to such a helical spring 50 at all.

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NEYMEYER & PARTNER GBR, Patent Attorneys MN/mn

iDingen^ jnveaningen (DE) November 17, 2000

Such a coil spring 50 is also shown as an example in Fig. 5.

It can be seen that this coil spring 50 is accommodated between two spring plates 51 and 52. In the present embodiment, these two spring plates 51, 52 have an angle of inclination δ to one another that is approximately 40°. Such a bent, pre-stressed mount of the coil spring 50 is frequently encountered in motor vehicle axle constructions, as is also shown by way of example in Fig. 5. For example, the upper spring plate 51 is mounted at an angle on the body 53, while the lower spring plate 52 can be arranged, for example, on a pivotably mounted wishbone 54.

It is easy to imagine that when tensioning a coil spring 50 that has been pre-tensioned in such a curved manner with conventional, i.e. non-inclined gripping elements, the disassembly and assembly of the coil spring 50 represents a potential hazard for the operating personnel, or that such a spring tensioner from the state of the art can only be used on such a coil spring with difficulty or not at all. This is because the correspondingly pre-tensioned coil spring 50 bends with increasing tension during the tensioning process with non-inclined gripping elements of a conventional spring tensioner.

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Neymeyer & Partner GbR, Patent Attorneys MN/mn

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This would in turn mean that, for example, when dismantling the coil spring 50, it can slip out of the upper spring plate 51 as well as the lower spring plate 52 with its respective end turns 55 and 56 still under pre-tension from the spring plates 51 and 52, since the end turns 55 and 56 follow this increasing straight alignment of the coil spring 50 with increasing tensioning path. During assembly, however, the coil spring tensioned in a conventionally designed spring tensioner with end turns 55 and 56 running parallel to the two transverse planes 57 and 58 shown as examples in Fig. 5 would have to be held in the two spring plates 51 and 52 with additional holding devices during the relaxation process. Only with increasing relief of the coil spring 50, when using a conventional spring tensioner, would the two end turns 55 and 56 of the coil spring 50 adapt in their inclination to the position of the inclined spring plates 51 and 52, until the coil spring 50, after complete relaxation, reaches the end position shown in Fig. 5 with its end turns 55 and 56.

The design according to the invention according to the embodiment shown in Fig. 5 enables both a safe disassembly and assembly of such a coil spring, which is bent and pre-tensioned when installed.

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50, as can be seen in particular from Fig. 6. For disassembly, the spring tensioner l/l with its two gripper elements 19/2 and 20/2 is placed on the two spring coils 59 and 60 of the bent, pre-tensioned helical spring 50. In the present embodiment, these two spring coils 59 and 60 have an angle of incidence ßl or ß2 to the respective transverse plane 57 or 58 of approximately 12° each, as can be seen from Fig. 5. This means that the angle of inclination ßl or ß2 in the present embodiment of the two spring coils 59 and 60 to the respective transverse plane 57 or 58 is greater than the angle of inclination a1 or a2 of 8° each of the two gripper elements 19/2 and 20/2 to the respective transverse plane 22 or 23 of the tensioning device 3/2. The two transverse planes 57 and 58 run at right angles to a straight connecting line 47 that passes through the two centers of the spring coils 69 and 60 to be accommodated. When the spring tensioner l/l is attached to the coil spring 50, this connecting line 47 is essentially parallel to the "longitudinal center axis" 2 8/2, which passes through the centers of the two gripper elements 19/2 and 2 0/2, as shown by way of example in Fig. 5. If the gripper elements 19/2 and 2 0/2 have the same diameter as the diameter of the coil spring 50, the connecting line 47 and the "longitudinal center axis" 28/2 of the gripper elements

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19/2 and 20/2 are essentially identical when the spring tensioner l/l is correctly attached to the coil spring.

When the spring tensioner l/l is attached to the coil spring 50, the transverse planes 22 and 57 or 23 and 58 are essentially congruent, but at least they run parallel to one another, as indicated by the corresponding reference numbers in Fig. 6 and 7.

The two angles of inclination a1 and a2 of the gripper elements 19/2 and 20/2 are large enough to prevent the two end turns 55 and 56 from slipping out of the two spring plates 51 and 52 when the coil spring 50 is tensioned, since the angle of inclination a1 and a2 maintains a curvature of the coil spring 50 when the coil spring 50 is tensioned, whereby an inclined position of the end turns 55 and 56 of the coil spring 50 is maintained even when tensioned. This remaining inclined position of the end turns 55 and 56 is at least large enough that the end turns 55 and 56 cannot accidentally slip out of the spring plates 51 and 52.

This pre-curved course of the coil spring 50 when the coil spring 50 is fully tensioned is shown as an example in Fig. 7. It is clearly visible that the axial distance between the two gripper elements

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Neymeyer & Partner GbR, Patent Attorneys MN/mn

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19/2 and 2 0/2 is reduced in such a way that the spring coils lie "block" against one another in the area of the inside of the curve. The coil spring 5 0 thus maximally tensioned "block" by the spring tensioner l/l has, as can be clearly seen from Fig. 7, a pre-curved course, as indicated by the curved center line 61 of the coil spring 50. It can be seen that the two end coils 55 and 56, which are not gripped by the gripper elements 19/2 and 20/2, also run inclined to the two transverse planes 22 and 23 running parallel to one another and at right angles to the longitudinal center axis 21/2 of the spring tensioner l/l, or to the transverse planes 57 and 58 which in this case are congruent. This angle of attack of the two end turns 55 and 56 is still so large, even with a smaller selected angle of inclination a1 or a2, that the coil spring 50 with its end turns 55 and 56 cannot slip out of the spring plates 51 and 52 during assembly.

As already explained in the introduction to the description, the angles of inclination a1 and a2 can correspond to the angles of attack ßl and ß2 of the spring coils of a curved pre-stressed helical spring to be accommodated. Such a design is particularly applicable to curved pre-stressed helical springs with a small radius of curvature of their curved course. Since the angles of attack ßl and ß2 also correspond to the angles of attack ßl and ß2 of the spring coils of a curved pre-stressed helical spring with a small radius of curvature of the helical spring,

K255.doc

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compared to the transverse plane of the spring coils to be accommodated are correspondingly small, e.g. can be in a range of about 5° to 10°, a complete relaxation of a helical spring removed from an axle construction, for example, can be carried out safely even with gripper elements inclined at a correspondingly small angle of attack a1 and a2, without the helical spring, which straightens itself during the relaxation process, being able to slip out of the gripper elements unintentionally.

In the case of a larger radius of curvature of a bent pre-stressed helical spring, however, the angles of inclination a1 and a2 of the gripper elements to the transverse plane should preferably be selected to be smaller than the angles of attack ßl and ß2 of the spring coils of the bent pre-stressed helical spring to be accommodated, in order to enable complete relaxation without the helical spring being able to slip out of the gripper elements, particularly at the end of the relaxation process due to its straight-line orientation.

Thus, the advantageous design of the spring tensioner according to the invention or its tensioning elements 4 and 5 according to the invention can be seen overall from the illustrated embodiments. By means of a curved tension of an unstable coil spring, it is ensured that

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that it cannot accidentally slip out of the gripper elements. Furthermore, if the angle of inclination a1 or a2 is adjusted accordingly to the curved course of a bent pre-tensioned coil spring, such coil springs can also be tensioned safely.

Claims (9)

1. Spring tensioner ( 1 , 1/1 ) for tensioning coil springs ( 2 , 50 ), comprising a tensioning device ( 3 , 3/2 ) on which two tensioning elements ( 4 , 4/2 , 5 , 5/1 , 5/2 ) are arranged, which are provided with gripping elements ( 19 , 19/2 , 20 , 20/1 , 20/2 ) for receiving the coil spring ( 2 , 50 ) to be tensioned, wherein by actuating the tensioning device ( 3 , 3/2 ) the distance between the tensioning elements ( 4 , 4/2 , 5 , 5/1 , 5/2 ) for tensioning and relieving the coil spring ( 2 , 50 ) can be changed, characterized in that the gripping elements ( 19 , 19/2 , 20 , 20/1 , 20/2 ) are arranged obliquely , converging towards one another, starting from the tensioning device (3, 3/2 ) and extending substantially at right angles to the longitudinal central axis (21 , 21/2 ) of the tensioning device ( 3 , 3/2 ) . 2. Spring tensioner ( 1 ) according to claim 1, characterized in that the angle of inclination (α1, α2 ) of the respective gripper element ( 19 , 20 , 20/1 ) to the transverse plane ( 22 , 23 ) is approximately 4° to 10°. 3. Spring tensioner ( 1/1 ) according to claim 1, characterized in that the angle of inclination (α1, α2) of the respective gripper element ( 19/2 , 20/2 ) is smaller than or at most equal to the angle of attack ( β1 , β2 ) of the respective spring coil ( 59 , 60 ) of the helical spring ( 50 ) to be gripped relative to the transverse plane ( 22 , 23 ) of the tensioning device ( 3/2 ) when the spring tensioner ( 1/1 ) is attached to the helical spring ( 50 ). 4. Spring tensioner ( 1 ) according to claim 1, 2 or 3, characterized in that the tensioning device ( 3 ) has a protective cover ( 64 ) pointing towards the coil spring ( 2 ) to be accommodated in the region between the tensioning elements ( 4 , 5 ). 5. Spring tensioner ( 1 ) according to claim 4, characterized in that the protective cover ( 64 ) is replaceably attached to the tensioning device ( 3 ) via a snap-in or clamping connection ( 66 , 67 ). 6. Spring tensioner ( 1 ) according to claim 4 or 5, characterized in that the axial position of the protective cover ( 64 ) on the tensioning device ( 3 ) between the tensioning elements ( 4 , 5 ) is variably adjustable. 7. Spring tensioner ( 1 , 1/1 ) according to one of claims 1 to 6, characterized in that the gripper element ( 20/1 ) is approximately fork-shaped or U-shaped and has an approximately L-shaped cross section with a support section ( 30/1 ) and an outer safety web ( 32/1 ), and that the support section ( 30/1 ) projects beyond the safety web (32/1 ) in the end region of the two U-legs (26/1 , 27/1 ) of the gripper element ( 20/1 ) . 8. Spring tensioner ( 1 , 1/1 ) according to claim 7, characterized in that the support section ( 30/1 ) of the respective U-leg ( 27/1 ) has a recess or notch (27 ' ) in its end region projecting beyond the safety web ( 32/1 ) in extension to the safety web (32/1 ) . 9. Spring tensioner according to one of claims 1 to 8, characterized in that the gripper elements ( 19 , 19/2 , 20 , 20/1 , 20/2 ) are designed in their circumferential length such that the spring coils ( 36 , 37 , 59 , 60 ) of a helical spring ( 2 , 50 ) to be tensioned rest on the respective gripper element ( 19 , 19/2 , 20 , 20/1 , 20/2 ) over an angle of up to approximately 240° , at least in the slightly pre-tensioned state of the helical spring ( 2 , 50 ) .