Adjustment device for a control cable

1. Field of the invention The present invention relates to an adjustment device for a control cable, which allows a simple and secure adjustment of the length of the control cable to the device to be actuated.

2. Prior art Control cables, which are also referenced as Bowden cables, are used among others in motor vehicles, machines or at bicycles. In general they act as a connection between an actuation device, for example a pedal or a lever, with a device to be actuated, for example a brake or a clutch. The length of the control cable between the actuation device and the device to be actuated has to be exactly adjusted, such that the device can be correctly actuated. Usually brakes or clutches are adjusted or re-adjusted via the length of the control cable.

Control cables can transmit pulling forces but also pressure forces to remote locations. They usually consist of a flexible sheath, which is formed of a wire spiral, which is covered with plastic material as well as of a cable, which is usually formed of a wire rope. The wire rope is freely displaceable within the sheath. The sheath in the first instance receives pressure forces, according to the field of application but also tensile forces. The cable in the first instance transmits tensile forces, but may also be used to transmit pressure forces.

Control cables of this kind are usually adjusted to a particular length, by changing the length of the sheath. The length of the cable is mainly kept constant. To this end, in the prior art different adjustment devices are known.

So, the EP 1 296 072 Al shows for example an adjustment device for the length adjustment of a control cable, comprising a cylinder shaped housing and an adjustment member, which is longitudinal displaceable therein, and which is biased by a spring against the cylinder shaped housing. The spring generates a pre- biasing force on the control cable, such that the control cable is automatically pre- biased. To permanently fix the adjustment member at the cylinder shaped housing the adjustment member is provided with latching means, which lock with corresponding latching means at the housing.

Other adjustment devices for control cables are for example known from the EP 1 406 023 A2, DE 197 06 866 Al or the WO 93/22571. All of these adjustment devices work according to the above described principle, i.e. they comprise springs, which apply a certain pretension to the control cable and which are then manually locked in that position. For this reason such adjustment devices are suit- able for the compensation of freeplay on the control cable, but are less suitable for the exact adjustment of the device to be actuated, for example a brake or a clutch, which perhaps needs a particular desired freeplay. For a correct function no pretension on the control cable is allowed.

Further such adjustment devices comprise often of a plurality of components and are comparably complicated to assemble or to adjust. By means of the provision of locking teeth further only an adjustment in particular predetermined steps is possible. Further, the mentioned adjustment devices are often only suitable for the transmission of forces in one load direction, i.e. either for tensile or pressure forces, due to the tooth shaped locking means. Finally these adjustment devices due to the locking mechanism often have a comparably high demand of space and can therefore not be used everywhere.

It is therefore the problem of the present invention to provide an adjustment de- vice for a control cable, which among others, is simple in design, easy to assemble, comprise a small space consumption, is suitable equally for the transmission

of tensile and pressure forces, which enables a stepless adjustment of the device to be actuated by means of the control cable and by which also a particular freeplay can be set.

3. Summary of the invention

The above problems are solved by an adjustment device according to the invention according to patent claim 1 and patent claim 12.

Particularly the above mentioned problems are solved by an adjustment device for a control cable comprising of a sheath and a cable, comprising a first threaded sleeve, comprising an outer thread in a first sense of rotation, a second threaded sleeve, comprising an outer thread in a second sense of rotation and an adjustment sleeve comprising a first inner thread in the first sense of rotation, which engages the outer thread of the first threaded sleeve and a second inner thread in the sec- ond sense of rotation, which engages the outer thread of the second threaded sleeve, wherein the first threaded sleeve is held rotatably fixed by means of a first part of the sheath of the control cable and the second threaded sleeve is held rotatably fixed by means of a second part of the sheath of the control cable.

The adjustment device according to the invention therefore consists essentially of three components, namely a first and a second threaded sleeve, as well as an adjustment sleeve. It is therefore simple in construction, robust and requires only little space. The threaded sleeves are fixed at the sheath of the control cable in such a way that they are held rotatably fixed. In that way the fact is used, that the sheath of the control cable is almost always layed rotatably fixed for example in a motor vehicle. Therefore no devices must be provided, to fix the threaded sleeves with respect to the adjustment sleeve.

By the provision of threads at the threaded sleeves respectively at the adjustment sleeve the control cable respectively the device actuated therewith can be adjusted

simply, steplessly and exactly by a rotation of the adjustment sleeve. With such an adjustment device it is also possible to set a desired freeplay.

Since the parts of the sheath of the control cable to be adjusted are further prefera- bly rigidly connected with the threaded sleeves, such an adjustment device is also suitable to transmit tensile forces as well as pressure forces.

Due to the two pairs of threads with opposed sense of rotation further a comparably large adjustment range is possible at a small space consumption of the adjust- ment device. Further, the adjustment sleeve is supported solely by the two pairs of threads. Additional support or contact faces between adjustment sleeve and the threaded sleeves or the sheath of the control cable are not necessary. Since the support is very friction less but can transmit high forces, the adjustment device is particular abrasion resistant and reliable. Further, by means of the two pairs of threads with an opposed sense of rotation, it is very easy to transmit pulling forces via the sheath of the control cable (and therefore pressure forces via the cable), which is not possible having a pure abutting of the sheath of the control cable at the adjustment sleeve.

In a preferred embodiment the first and the second threaded sleeve each comprise a receptacle opening, respectively, which is dimensioned such that it forms an interference fit with the corresponding part of the sheath of the control cable. In this embodiment the threaded sleeves of the adjustment device are pressed on the ends of the parts of the sheath with a particular pressure, such that they are held rotatably fixed by means of parts of the sheath of the control cable.

In a further preferred embodiment a part of the sheath of the control cable is positively connected with the corresponding first and second threaded sleeve, respectively. Instead of an interference fit also a positive fit connection can be provided, for example by a corresponding profiling of the receptacle in the threaded sleeve

and the sheath of the control cable. In this case it is also secured, that the threaded sleeve does not rotate with respect to the sheath of the control cable.

Preferably the receptacle openings comprise retention structures at their inner sides. The inner sides of the receptacle openings are preferably suitable structured, to prevent a rotation of the threaded sleeve with respect to the sheet of the control cable. A possible structuring are for example ribs or teeth, which run in parallel to the middle axis of the adjustment device.

In a further preferred embodiment one part of the sheath of the control cable is glued with the corresponding first and second threaded sleeve, respectively. By a gluing of the threaded sleeve to the sheet of the control cable it is also secured, that the threaded sleeves do not rotate with respect to the parts of the sheet of the control cable.

In a further preferred embodiment one part of the sheath of the control cable is thermally welded with the corresponding first and second threaded sleeve, respectively. A thermal welding of the threaded sleeve to the sheath of the control cable generates a particular rigid connection between the threaded sleeve and the sheath of the control cable, like the gluing. In case of a thermal welding no additional glues are required, if the threaded sleeve and the sheath of the control cable comprise plastic materials. Further, a thermal welding can be loaded immediately, since no glues must cure or dry.

In a further preferred embodiment the adjustment sleeve comprises at lease one resilient tab, which is biased in a direction perpendicular to the middle axis. This resiliently biased adjustment sleeve acts for the securing of the position of the adjustment sleeve, by generating a friction effect between adjustment sleeve and threaded sleeve, which prevents from an undesired rotation, i.e. disadjustment, of the adjustment sleeve.

Preferably, the tab is completely inserted into the wall of the adjustment sleeve. By means of the insertion of the tab into the wall of the adjustment sleeve, the tab is protected in tangential direction against a rotation and does not essentially extend in radial direction over the body of the adjustment sleeve. Therefore, on the one hand the tab can not brake and on the other hand it does not provide an attack face for a contact with other elements of the motor vehicle, which could lead to an undesired adjustment of the adjustment device. Further, such a "sunken" arrangement of the tab prevents that an assembling person is injured at the tab during adjustment. Finally, by such an arrangement the outer threads of the threaded sleeves were covered and thereby a damage of the outer threads is avoided.

In a further preferred embodiment the first and/or the second threaded sleeve comprise at their outer side notch elements, which run in parallel to the middle axis. For an improvement of the friction effect between the resilient tab or the resilient tabs of the adjustment sleeve and the threaded sleeve or the threaded sleeves notch elements are provided for example in the shape of grooves or teeth, which engage the resilient tab or the resilient tabs.

In a further preferred embodiment the adjustment sleeve comprises a knurling at their outer side for facilitating the manual actuation. By the knurling, which is provided preferably in form of ribs or grooves, a manual rotation of the adjustment sleeve (with only one hand) is facilitated.

In a further preferred embodiment the adjustment sleeve comprises at least one visible and/or tangible direction index. A direction index at the adjustment sleeve facilitates the assembly of the adjustment device, particularly at otherwise symmetrically constructed adjustment sleeves, since now the threaded sleeve with the correct thread (right hand or left hand thread) can be screwed into the correct side of the adjustment sleeve.

In a preferred embodiment the threaded sleeve and the adjustment sleeve comprise of a plastic material, particular of PA 6.6.

The above mentioned problems are also solved by an adjustment device for a con- trol cable comprising of a sheath and a cable, comprising a threaded sleeve, comprising an outer thread, an adjustment sleeve, comprising an inner thread which engages the outer thread of the threaded sleeve, wherein the adjustment sleeve is rotatably mounted at a first part of the sheath of the control cable, and the threaded sleeve is held rotatably fixed by means of a second part of the sheath of the control cable.

This further embodiment of an adjustment device according to the invention uses the same principle according to the invention according to which the threaded sleeve is held rotatably fixed by means of the sheath of the control cable, whereas the adjustment sleeve is rotatable. Thereby devices are eliminated also here which otherwise hold the threaded sleeve rotatably fixed. As a difference to the above described first embodiment here only one threaded sleeve is used together with an adjustment sleeve, wherein the adjustment sleeve is rotatably mounted at a part of the sheath of the control cable.

The other features of the initially described embodiment, particularly the possibilities of mounting of the threaded sleeves at the parts of the sheath and the particular arrangement and design of the resilient tab for securing the position of the adjustment sleeve, can be transferred to this embodiment. Thereby, the above de- scribed corresponding advantages result also for this embodiment.

In the simplest case the adjustment sleeve abuts against the end of the sheath of the control cable. Thereby, an adjustment device for a control cable is provided which only comprises of two components. In this case a particular simple and cost efficient adjustment device is provided.

In another case the adjustment sleeve preferably is further not mounted displace- ably in direction of the middle axis at the first part of the sheath of the control cable. Then, also this adjustment device can transmit tensile as well as pressure forces.

Further a control cable is claimed, which comprises an adjustment device with the above mentioned features.

Further preferred embodiments of the invention result from the sub claims.

4. Short description of the drawings

In the following preferred embodiments of the invention are described with reference to the drawings. Therein it shows:

Fig. 1 a longitudinal sectional view through the middle axis of an adjustment device according to the invention for a control cable, together with parts of the control cable; a detail of the adjustment device is shown enlarged;

Fig. 2 a sectional view of the adjustment device of Fig. 1 taken along the line A - A in Fig. 1;

Fig. 3 a three-dimensional view of an adjustment device according to the invention, together with parts of a control cable in a first adjustment position; and

Fig. 4 a three-dimensional view of the adjustment device of Fig. 3 in a second adjustment position.

5. Detailed description of the preferred embodiments In the following with reference to the drawings embodiments of the present invention are described in detail.

Figure 1 shows in a longitudinal sectional view through the middle axis 2 a first preferred embodiment of the adjustment device 1. The adjustment device 1 consists essentially of three components: A first threaded sleeve 10, a second threaded sleeve 20 and an adjustment sleeve 30. The adjustment device 1 acts for an adjustment of the length of the control cable 56, 60, 70 which comprises of a continuous cable 50 and a sheath 60, 70 which is divided by means of the adjustment device 1 into a first part 60 and a second part 70.

The first threaded sleeve 10 comprises an outer thread 12 in a first sense of rotation, for example a left handed thread. In mounted condition the outer thread 12 of the first threaded sleeve 10 is screwed into a first inner thread 31 of the adjustment sleeve 30. If the outer thread 12 is a left handed thread, the first inner thread 31 must also be a left handed thread.

Analogue thereto the second threaded sleeve 20 comprises an outer thread 22, which is screwed into a second inner thread 32 of the adjustment sleeve 30. The outer thread 22 of the second threaded sleeve 20 comprises a second sense of rotation, i.e. if the outer thread 12 of the first threaded sleeve 10 is a left handed thread, the outer thread 22 of the second threaded sleeve 20 is a right handed thread. Corresponding thereto the second inner thread 32 of the adjustment sleeve 30 must be a right handed thread.

If the outer thread 12 of the first threaded sleeve 10 is a right handed thread, the outer thread 22 of the second threaded sleeve 10 is a left handed thread.

By means of the opposed sense of rotation of the threads 22, 32 with respect to the threads 12, 31 it is achieved that the threaded sleeves 10, 20 during a corresponding rotation of the threaded sleeve 30 either both are screwed into the adjustment sleeve 30 or both threaded sleeves 10, 20 are screwed out of the adjustment sleeve 30.

During a screwing out of the threaded sleeves 10, 20 out of the adjustment sleeve 30 the sheath 60, 70 "elongates" such that correspondingly the cable 50 effectively is "shortened". If the threaded sleeves 10, 20 are screwed into the adjust- ment sleeve 30, the sheath 60, 70 of the control cable is shortened, such that the cable 50 of the control cable is effectively "elongated". Thereby it is possible to adjust the effective length of the control cable 50, 60, 70 by means of a rotation of the adjustment sleeve 30.

A first part 60 of the sheath 60, 70 is inserted into a receptacle opening 14 of the first threaded sleeve 10 and prevents a rotation of the first threaded sleeve 10. To this end the diameter of the receptacle opening 14 can be selected such that an interference fit results between the receptacle opening 14 and the first part of the sheath 60. This means, that the end of the sheath 60 must be pressed into the re- ceptacle opening 14 by means of a certain force effort. This applies also for the part 70 of the sheath 60, 70 which is inserted into the receptacle opening 24 of the second threaded sleeve 20 and which holds the threaded sleeve 20 rotatably fixed. Since the sheath 60, 70 usually is rotatably fixed laid for example within a motor vehicle, in that way the first and the second threaded sleeve 10, 20 can be particu- larly held rotatably fixed in a simple manner.

Instead of or additionally to an interference fit between the sheath 60, 70 and the receptacle openings 14, 24 the parts 60, 70 of the sheath of the control cable can also be connected positively with the first and the second threaded sleeve 10, 20. Such a positive fit results for example in that the inner sides of the receptacle openings 14, 24 are provided with longitudinal grooves, which cut into the sheath of the control cable during the pressing in of the parts 60, 70. This is particularly possible if the outer sides of the sheath 60, 70 are covered with a plastic material.

In another embodiment the receptacle openings 14, 24 can for example be hexag- onally profiled and the sheath of the Bowden cable at its end could correspondingly be hexagonally profiled to prevent a rotation of the threaded sleeves 10, 20.

Further, the sheet of the control cable 60, 70 can be glued with the corresponding first 10 and second threaded sleeve 20. To this end on the outer side of the sheath 60, 70 a glue is applied and then the sheath 60, 70 is inserted into the corresponding receptacle openings 14, 24. After the hardening respectively curing of the glue a rigid connection between the threaded sleeves 10, 20 and the corresponding parts of the sheath 60, 70 results.

Alternatively a part 60, 70 of the sheath of the control cable could be thermally welded with a corresponding first 10 and second threaded sleeve 20, respectively. Such a thermal welding can immediately be loaded and provides a connection which can withstand high loads between the sheath of the control cable 60, 70 and the first 10 and the second threaded sleeve 20. To this end a part 60, 70 of the sheath of the control cable is completely inserted into the corresponding receptacle openings 14, 24 of the first and the second threaded sleeve 10, 20. After that the first respectively the second threaded sleeve 10, 20 is welded from the outside with the parts 60, 70 of the sheath of the control cable for example by pressing a heated pin-shaped tool through the threaded sleeve 10, 20 to the sheet of the control cable 60, 70. At this position a part of the material of the sheath of the control cable 60, 70 welds with the material of the corresponding first and second threaded sleeve 10, 20. Alternatively it is also possible to injection mould the threaded sleeves 10, 20 directly to the sleeve 60, 70 of the control cable.

As it is shown in Fig. 2 the adjustment sleeve 30 comprises at least one resilient tab 33, 34, 35, 36 which is resiliency biased in direction perpendicular to the middle axis 2. Figure 2 shows the tabs 33 and 34 which press to the inside in direction of the middle axis 2, i.e. in direction to the cable 50. The tabs 33, 34 further comprise a tip 37, 38, respectively, which engages with notch elements 26 on the sec-

ond threaded sleeve 20. If the adjustment sleeve 30 is rotated first the tabs 33, 34 have to be moved to the outside against their pre-biasing to get out of engagement with the notch elements 26 and to allow a rotation. The tabs 33, 34, 35, 36 therefore prevent an undesired rotation of the adjustment sleeve 30 with respect to the threaded sleeves 10, 20 and thereby an undesired disadjustment of the adjustment device 1.

As it is shown in Fig. 1 and Fig. 3 the adjustment sleeve 30 in total comprises four resilient tabs 33, 34, 35, 36. The tabs 33, 34, 35, 36 are each inserted, integrated respectively "sunken" into the cylindrical Wall 41 or the body of the adjustment sleeve 30. To this end an essentially U-shaped slot 42 is provided within the wall 41, which extends through the wall 41 and which defines the tabs 33, 34, 35, 36, respectively. Thereby, also a bar 43 is formed at the face side of the adjustment sleeve 30, which protects the tabs 33, 34, 35, 36 from the outside. Therefore, the tabs 33, 34, 35, 36 do not provide an attack face for an undesired adjustment by other components of the motor vehicle.

As it is shown in Fig. 3 such a sunken or integrated Arrangement of the tabs 33, 34, 35, 36 also leads to a covering of the outer threads 12, 22 of the threaded sleeve 10, 20 and thereby to protect them from damages from the outside. Thereby, the reliability of the adjustment device 1 is improved.

The notch elements 16, 26 are preferably in the shape of a toothing at the outer side of the threaded sleeves 10, 20, which runs in parallel to the middle axis 2.

For facilitating the manual actuation of the adjustment device, i.e. for an easier rotation of the adjustment sleeve 30, it comprises a knurling 39 at its outside. In the shown embodiment the knurling 39 is made in the form of ribs, which run in parallel to the middle axis 2. Other forms of the knurling 39 are of course possi- ble.

As it is shown in Fig. 3 the adjustment sleeve 30 comprises at its outer side a visible and tangible direction index 40, which preferably marks the side of the adjustment sleeve 30, which is provided with the left handed thread. Therefore, the assembly of the adjustment device 1 is facilitated, since the assembling person now can select the appropriate threaded sleeve 10, 20 (with a right handed or left handed thread) and can screw it in.

In Fig. 3 a position of the adjustment device 1 is shown, in which the threaded sleeves 10, 20 are only screwed into the adjustment sleeve 30 by a short distance. In this case the sheath 60, 70 is "elongated". Fig. 4 however shows a position of the adjustment device 1 at which the threaded sleeves 10, 20 are screwed into the adjustment sleeve 30 by a large distance. In this case the sheath 60, 70 of the control cable is "short", respectively the effective length of the cable 50 of the control cable is long.

In Fig. 4 it is exemplarily shown how the effective length of the Bowden cable 50, 60, 70 can be adjusted by means of the adjustment device 1. The cable 50, which is intended to transmit preferably a tensile movement of an actuator, for example a lever or a pedal, to a device to be actuated, for example a clutch or a brake is freely displaceable within the sheet 60, 70 and within the adjustment device 1. The adjustment of the effective length of the control cable is done by an adjustment of the length of the sheath 60, 70.

For the purpose of the following description it is now assumed, that the threaded sleeve 10 is provided with a left handed thread 12 and the threaded sleeve 20 with a right handed thread 22. If the adjustment sleeve 30 is rotated in direction 82, whereby the threaded sleeves 10 and 20 are rotatably fixed by means of the parts

60, 70 of the sheath of the control cable is held, the threaded sleeve 10 moves in direction 86 and the threaded sleeve 20 in direction 86 out of the adjustment sleeve 30. Thereby, the effective length of the sheath 60, 70 is elongated and the one of the cable 50 is correspondingly shortened.

If, however, the adjustment sleeve 30 is rotated in direction 80, the threaded sleeve 10 moves in direction 84 and the threaded sleeve 20 in direction 84 into the adjustment sleeve 30. Thereby, the effective length of the sheath 60, 70 is short- ened and the effective length of the cable 50 is correspondingly elongated.

In a further embodiment of the adjustment device according to the invention (not shown) the second threaded sleeve 20 is omitted and the part 60 of the sheath of the Bowden cable is directly rotatably connected with the adjustment sleeve 30. In a preferred embodiment the end of the part 60 of the sheath of the control cable abuts within a corresponding large receptacle opening of the adjustment sleeve 30. Therefore, this adjustment device consists only of two parts and is therefore very cost efficient and small.

In another embodiment the adjustment sleeve 30 is not displaceably mounted in direction of the middle axis 2 but rotatably fixed at the first part 60 of the sheath of the control cable. In this case also this embodiment can transmit tensile forces as well as pressure forces.

This further embodiment corresponds to a simplified embodiment of the adjustment device 1 shown in Figs. 1 to 5 and described above. The particular features of the above described adjustment device 1 , particularly the possibilities to mount the sheath 60, 70 of the control cable at a threaded sleeve 10, 20, can also be applied to this embodiment. Further, the particular design and arrangement of the resilient tabs 33, 34, 35, 36, which are integrated into the wall 41 of the adjustment sleeve can be applied to this embodiment.

This second embodiment is particularly helpful, if very fine adjustments have to be done. Besides this, such an adjustment device is particularly small and space efficient and only needs two moveable components. Therefore it is particular cost- efficient in manufacturing and free of maintenance.

A plastic material particularly polyamide PA 6.6 is used as a material for the threaded sleeve 10, 20 and the adjustment sleeve 30. The cable 50 preferably consists of a steel cable with a plurality of twisted fibres and the parts 60, 70 of the sheath of the Bowden cable consists of a wire spiral which is covered with a plastic material.

List of reference signs

1 adjustment device

10 threaded sleeve

12 outer thread

14 receptacle opening

16 notch elements

20 second thread sleeve

22 outer thread

24 receptacle openings

26 notch elements

30 adjustment sleeve

31 first inner thread

32 second inner thread

33, 34, 35, 36 resilient tabs

37, 38 tips

39 knurling

40 direction index

41 wall

42 U-shaped slot

43 bar

50 cable

60 first part of the sheath of the control cable

70 second part of the sheath of the control cable

80 first rotational direction

82 second rotational direction

84 first displacement direction

86 second displacement direction