Spring compressor and jaw and extension unit for a spring compressor

The present invention relates to a spring compressor and to a jaw and an extension unit for a spring compressor. Spring compressors are commonly used in garages and workshops where vehicles are serviced and repaired. The spring compressor is e.g. used for compressing a vehicle suspension spring to enable replacement of a shock absorber.

The spring compressor has two jaws which receive the suspension spring near the ends of the spring. The spring is subsequently compressed by contraction of the jaws with a spindle drive, which is normally driven by a pneumatic power tool.

BACKGROUND OF THE INVENTION

Almost any vehicle is equipped with suspension springs adapted for exactly that vehicle.

This means that even in cars from the same manufacturer, every model has different suspension springs. The springs differ in length, diameter, pitch angle etc., and some are helical, others conical or barrel shaped. To handle the immense variety of springs, an equal variety of spring compressor jaws is used. Handling and storing such an amount of jaws is of course cumbersome, and jaws are often mislaid after use due to normal commotion in a busy garage or workshop.

The variety in shape of the springs means that even when a set of jaws matches a particular spring with respect to diameter and pitch angle, sometimes the shape causes one or both jaws to be too short because the spring will interfere with the housing of the spring compressor. This is particularly the case with barrel shaped and conical springs. To compensate for this, an extension unit is sometimes used to off-set the jaw instead of using an extended jaw which is the standard solution. The extension unit is also used to ensure that the spring compressor and the centre axis of the spring are parallel and aligned, which is a safety issue. However, in case of a spring which is too long, a different spring compressor with sufficient reach must be used.

SUMMARY

It is an object of the present invention to provide solutions to the aforementioned drawbacks of the known spring compressors and jaws, including providing solutions which are more flexible and require a lesser amount of different items to be used. Other objects appear from the description and the appended figures.

One aspect of the invention involves a jaw for a spring compressor, which jaw has a spring engagement part with a contact surface adapted to receive a spring turn of a spring to be compressed, said contact surface comprising at least one outer section being adapted to receive larger diameter spring turns as well as at least partly receive smaller spring turns

and having U-shape, and at least two inner sections extending from the outer section and inwardly relative to the U-shape of the outer section, said inner sections being adapted to receive smaller diameter spring turns, where the inner sections each comprise an inward, preferably straight, surface, which inner sections together form a V-shape. Such a jaw may be used e.g. for springs having different diameters, whereby one such jaw can replace a large number of jaws each matching a particular diameter.

In one preferred embodiment of the jaw, the outer section and the inner section may have a pitch angle which is less than a pitch angle of a spring turn to be received by the jaw. This provides an improved and more even distribution of the contact pressure between the spring turn and the contact surface. At the start of a compression, the spring turn which is in engagement with the jaw will elastically adapt its shape to the lesser pitch angle. This will, however, lead to increased contact pressure on the part of the contact surface which is engaging the part of the spring turn which is closer to the end of the spring, said end being the end of the spring which is near the location where the jaw is engaging the spring. The contact pressure on this part would otherwise be less. When the contact pressure is increased on this part, it is reduced on the remaining part of the contact surface, where it would otherwise be very high. An improved distribution of the contact pressure is advantageous because it reduces the maximum pressure, whereby deterioration of the spring surface is reduced and the lifespan of the spring is increased. Improved distribution of the contact pressure reduces the hazard of a spring accidentally flipping out. This hazard is higher when the contact pressure is high in a concentrated contact area.

Another preferred embodiment involves that the inner sections can extend from positions neighbouring a bottom of the U-shape of the outer section to positions near or at ending regions of the U-shape. This provides a shape where the inner sections have a minimised size where spring turns of different diameters may still be received, but without unduly increasing the weight of the jaw.

In a further preferred embodiment the V-shape has an angle of between 60 and 100 degrees, preferably 70 and 90 degrees, and more preferred 75 and 85 degrees. This provides a shape allowing engagement of both large and small springs.

In a yet further preferred embodiment at least one safety notch may be arranged to be in engagement with a spring turn at an inner side of said spring turn. This improves engagement of the springs and thereby gripping safety. This is further enhanced when the U-shaped outer section comprises an outwardly facing safety rim.

In a further preferred embodiment at least one inner section and/or the outer section may comprise a slanting surface. This also relates to the aforementioned theme of even distribution of the contact pressure between the spring and the contact surface. In some situations the spring may rest on an outer edge of the contact surface of a jaw. By slanting a surface of the inner section and/or outer section where this may otherwise occur, the problem is avoided and the pressure more evenly distributed.

Another aspect of the invention involves a disk-like safety insert adapted to be used with a jaw for a spring compressor. The insert has a shape which is adapted to the contact surface of the jaw, a thickness of at least 2 millimetres and is made from a polymeric material having a hardness of at least Shore 85 A. The material is preferably being solid thermoplastic polyurethane (TPU). When in use, the insert is arranged on the jaw and lies between the jaw and a spring in engagement therewith. The combination of the material, the hardness and a thickness of minimum 2 millimetres leads to a very firm and secure grip of the spring. This results from the material having high friction and because the spring due to high pressure makes a depression in the insert which on top of the friction creates a sort of positive or physical engagement which locks and keeps the spring in place.

A further aspect of the invention involves a spring compressor having at least one housing and at least two mounting blocks, said mounting blocks each being adapted to receive a spring compressor jaw, the spring compressor comprising a spindle arranged to induce a relative contraction of the mounting blocks when driven, and at least one extension unit adapted to be fitted between a mounting block and a spring compressor jaw, where the mounting block and the extension unit are mutually adapted in a manner where the extension unit, when in use, may be arranged in at least two positions relative to the mounting block, a first position where the jaw is at least off-set from the mounting block in a direction radially away from the spindle, and a second position where the jaw is at least off-set relative to the mounting block in a longitudinal direction along the spindle. Such a configuration makes it possible, with the same spring compressor, to receive and compress springs having different shapes, such as conical or barrel shapes, as well as springs with a length which would otherwise require a longer spring compressor. This provides an additional option of having a longitudinally adjustable working length of the spring compressor when the extension unit is used.

In one preferred embodiment the extension unit and the mounting block may be adapted for positive engagement when the extension unit is in use. This provides increased safety.

Another preferred embodiment involves that the spring compressor may comprise two extension units fitted to the mounting blocks. Two extension units provide an option of handling springs with a shape such as barrel springs as well as increased adjustable working length of the spring compressor, when both extension units are in use.

A yet further aspect of the invention involves an extension unit adapted to be used with a spring compressor having at least one housing, at least two mounting blocks and a spindle arranged to induce a relative contraction of the mounting blocks when driven, said blocks each being adapted to receive a spring compressor jaw, and where the extension unit is adapted to be fitted between a mounting block and a spring compressor jaw in at least two positions relative to the mounting block, a first position where the jaw is at least off-set from the mounting block in a direction radially away from the spindle, and a second position where the jaw is at least off-set relative to the mounting block in a longitudinal direction along the spindle, when the extension unit is in use. Such an extension unit makes it possible, with the same spring compressor, to receive and compress springs having different shapes, such as conical or barrel shapes, and also springs with a length which would otherwise require a longer spring compressor. This provides an additional option of providing a longitudinally adjustable working length of the spring compressor, when the extension unit is used.

BRIEF DESCRIPTION OF THE FIGURES

Fig. 1 is a perspective view of a jaw for a spring compressor;

Fig. 2 is a top view of a jaw for a spring compressor engaging a larger diameter spring; Fig. 3 is a top view of a jaw for a spring compressor engaging a smaller diameter spring;

Fig. 4 is a front view of a jaw for a spring compressor;

Fig. 5 is a side view of a spring compressor without jaws;

Fig. 6 is a side view of a spring compressor with an extension unit and two jaws ready to receive a conical spring; Fig. 7 is a side view of a spring compressor with two extension units engaging a barrel shaped spring; Fig. 8 is a side view of a spring compressor with two extension units engaging an oversized spring.

DETAILED DESCRIPTION OFF PREFERRED EMBODIMENTS

The figures show exemplary embodiments according to various aspects of the invention. The figures are merely included as information given as examples to a skilled person of how the invention may be carried out.

Figs. 1-4 display a jaw 2 for a spring compressor. The jaw 2 has a spring engagement part with a contact surface adapted to receive a spring turn. The contact surface has an outer section 3 which is adapted to receive larger diameter spring turns as well as smaller spring turns and which has a general U-shape. Two inner sections 4 of the contact surface extend from the outer section 3 and inwardly relative to the U-shape of the outer section 3. The inner sections 4 are adapted to receive smaller diameter spring turns. The inner sections 4 extend from positions neighbouring a bottom 5 of the U-shape of the outer section 3 to positions at end regions 6 of the U-shape. The jaw 2 has a connector 30 adapted for being fitted to a spring compressor.

Fig. 1 displays that the right-hand inner section 4 has two slanting surfaces 16, 18, where the slanting surface 16 at the inner section 3 extends inwardly relative to the U-shape and the other slanting surface 18 is tangential to the outer surface 3. Such slanting surfaces may result in a more even pressure distribution in situations where the spring rests on an outer edge of the contact surface of a jaw. A safety rim 12 is provided to secure large diameter springs.

In fig. 2, a jaw 2 is displayed which is engaging a larger diameter spring 26. The spring 26 is in engagement with a U-shaped outer contact surface 3. The U-shaped outer surface 3 has a bottom 5.

In fig. 3, a jaw 2 is displayed which has inner sections 4 of the contact surface having straight surfaces 7, which together form a V-shape. This provides a shape allowing engagement of both large and small rings. The displayed V-shape has an angle of about 78 degrees. In fig. 3 is a jaw 2 engaging a smaller diameter spring 28. Two safety notches 14 secure the inner side 10 of the spring 28. The smaller diameter spring 28 is received by the inner sections 4 and in part by the outer section 3.

Preferably, there is a disk-like safety insert (not shown) provided on the contact surface, including on the sections 3, 4. The insert lies between the jaw and a spring in engagement therewith in order to create a physical engagement which locks and keeps the spring in place. Such a physical engagement is typically obtained by use of a material having high friction and elasticity which allows the spring to make a depression in the insert which on top of the friction creates a sort of positive or physical engagement which locks and keeps the spring in place. The insert may be attached to the jaw 2 with glue or by having

protruding mounting tabs adapted to be received in suitable reception openings in the jaw. This aspect is not shown in the figures.

In fig. 4 it is displayed that one side A is higher than the other side B which indicates the presence of a pitch angle. The jaw 2 is preferably designed with a pitch angle of between 6 and 10 degrees, more preferred between 7 and 9, and most preferred about 8 degrees.

Figs. 5-8 display spring compressors 1 having a housing 20 and two mounting blocks 22. Some spring compressors have more housings arranged telescopically. A spindle (not shown) is arranged inside the housing and is adapted to provide a relative contraction of the mounting blocks 22 when driven. In this example one mounting block 22 (right-hand side) is fixed to the housing 20 and the other is displaceable. The unshown spindle is typically driven by connecting a power tool to an unshown reception in a drive wheel 32. The mounting blocks 22 are adapted to receive a spring compressor jaw 2 or an extension unit 24, such as displayed in fig. 6.

As indicated in figs. 6-8 the extension units are adapted to be fitted between a mounting block 22 and a spring compressor jaw 2. The mounting blocks 22 and the extension units 24 are mutually adapted in a manner where the extension unit 24 can be arranged in at least two positions, or multiple positions, relative to the mounting blocks 22, a first position where the jaws 2 are off-set from the mounting blocks 22 in a direction radially away from the unshown spindle, and a second position where the jaws 2 are off-set relative to the mounting block in a longitudinal direction along the unshown spindle. Of course, the extension units 24 may also be adapted to off-set the jaws 2 radially away as well as in a longitudinal direction. The extension units 24 may also be used in a situation where one unit 24 is off-setting a jaw 2 radially away and the other extension unit 24 is off-setting in a longitudinal direction. Any combination is possible. The extension units 24 are preferably secured to the mounting blocks 22 with unshown screws or bolts. Figs. 7 and 8 show a spring compressor 1 in engagement with a barrel shaped spring 34 and an oversized, i.e. too long, helical spring 36, respectively.

It is to be understood that the invention as disclosed in the description and in the figures may be modified and changed and still be within the scope of the invention as claimed hereinafter.