WO2008155203A1

WO2008155203A1 - Eccentric disk tensioning device

Info

Publication number: WO2008155203A1
Application number: PCT/EP2008/056580
Authority: WO
Inventors: Niels FLÄMIG; Bernd Hartmann
Original assignee: Schaeffler Kg
Priority date: 2007-06-20
Filing date: 2008-05-29
Publication date: 2008-12-24
Also published as: DE202007008685U1

Abstract

The invention relates to an eccentric disk tensioning device for a traction mechanism drive, having a roller unit comprising a race (9) and an antifriction bearing (8) for supporting the same, a working eccentric disk (7) for supporting the roller unit such that said unit can be displaced in a radial direction to a circumferential axis of the antifriction bearing in accordance with the pivoting of the working eccentric disk, a torsion spring (15) for pre-tensioning the working eccentric disk into a predetermined pivoting direction, a fixing device for securing the working eccentric disk in an assembly position in which the torsion spring is positioned in a pre-tensioned state, and a base plate structure (4) that can be affixed in a non-rotatable manner to a flange surface provided for connecting the eccentric disk tensioning device, wherein the fixing device comprises a section of the base plate, the section radially projecting from a circumferential region of the roller disk, and wherein a securing structure (18) is configured at this section (4a), via which an indicator element (16), which also radially projects from the circumferential region of the roller unit, can be fixed.

Description

Name of the invention

Eccentric tensioning device

description

Field of the invention

The present invention relates to an eccentric tensioning device for tensioning an example of a flat or toothed belt running traction means of a traction mechanism drive. In particular, the invention relates in this case to an eccentric clamping device provided for incorporation into a traction mechanism drive of an internal combustion engine which automatically ensures a required pretensioning of the traction means by means of an adjusting torque generated by a spring device.

A clamping device of the aforementioned type is known for example from US 2004/0180745 A1. This conventional tensioning device, also referred to as a double eccentric tensioning device, comprises an adjustment eccentric which has an off-centered bore provided for receiving a fastening screw. By means of the fastening screw, the tensioning device is attached to a housing, in particular a housing of the internal combustion engine. On this adjustment eccentric a working or operating eccentric is placed, wherein in an annular gap between a mantle surface of the adjustment eccentric and an inner wall of the operating eccentric a plain bearing bush is provided. On the Betriebssexzenter a Wälzla ger is mounted whose outer ring carries a race. This race is seated in the installed state with its outer peripheral surface on the traction means of the traction mechanism drive and loads it with a transversely oriented to the direction of the traction means transverse force. To achieve a frictional contact of the race on the traction means a Torshonsfeder is arranged between a base plate and the operating eccentric, which is the operating eccentric and permanently urges the wearer to carry it in a direction that pulls the traction means. In this known tensioning device, an axial bore is formed in the region of a front end surface of the working eccentric in which a bolt element can be inserted that rotatably couples the work eccentric in a specific pivot position with the adjustment eccentric.

The invention has for its object to provide solutions by which robust and inexpensive to produce eccentric tensioning devices can be created fen whose assembly and integration in a traction mechanism drive can be accomplished in a manner advantageous from a technical assembly point of view.

This object is achieved by an eccentric tensioning device for a traction drive, with:

a roller device which, as such, comprises a race and a bearing provided for supporting the same,

a working eccentric for supporting the roller device such that it can be displaced in a direction radial to the axis of rotation of the bearing in accordance with a pivoting of the working eccentric,

a torsion spring for biasing the working eccentric in a predetermined pivoting direction,

- A fixing device for securing the working eccentric in a mounting position in which the torsion spring is in a prestressed state, and

a base plate structure which can be anchored in a rotationally fixed manner to a flange surface provided for connecting the eccentric tensioning device,

- wherein the fixing device comprises a portion of the base plate which protrudes radially over a peripheral region of the running disk, and wherein on this section a securing structure is formed via which a ra-dial over the peripheral region of the roller device hervororkragendes Zei-ger element can be fixed. This advantageously makes it possible to provide a tensioning device in which the working or operating eccentric is fixed under pretensioning of the torsion spring in an end position pivoted away from the traction-centering track during assembly of the traction device, this securing state being in the frame the Verbaus the tensioning device can be canceled by manual unlocking the safety device. The working eccentric is preferably fixed in each locking or mounting position so that relative movements between the working eccentric and the base plate are prevented. As a result of this securing device, there are no impairments of the dirt seal in the inner region of the clamping device.

The securing structure is designed according to a particularly preferred embodiment of the invention as a plug-in bore. In this insertion hole, for example, designed as a plug-in safety pin securing element can be inserted. This securing element can be designed in particular as a wire bending part.

On the fuse element geometries can be realized by which a required for a secure locking plug-in state is set. Furthermore, additional holding members may be formed on the securing element and contribute to the fact that the securing element is not unintentionally released from the securing structure. In particular, it is possible to design the securing element in such a way that, before withdrawal from the insertion opening, it must be pivoted about an unlocking angle of, for example, 90 ° about the insertion axis, and can only be withdrawn in this position. This advantageously achieves a transport safety effect.

The tensioning device can be designed such that the pointer element rests against the securing element via a lateral outer surface section. However, it is also possible to form in the pointer element one or more through-holes, which in locking position with the Einsteckboh- aligned so that the securing state is brought about by inserting the securing pin in the through holes and the insertion holes.

Overall, the tensioning device according to the invention is preferably also designed so that the securing pin can be pulled out of the securing structure from an outside or radially adjacent section of the outer peripheral area of the raceway. Preferably, the securing pin is also designed so that it does not protrude axially in the inserted state via a front end face of the raceway. This makes it possible to stack corresponding clamping devices with high packing density in layers, in particular only with the interposition of a release carton to each other. It is possible to make the securing pin so that it completes substantially with that of the front end face and must be deducted for unlocking this front face Fron. As a result, a transport securing device for the lower layer is achieved by the respective next layer resting on a packing layer of the clamping devices. Structures, in particular apertures, can be punched into the separating carton or another intermediate layer by means of which effective positioning, in particular securing against lateral slipping of the tensioning devices, is achieved. These openings can be designed in particular in such a way that they interact with the anchoring structure of the base plate of the tensioning device which engages in the flange surface.

As an alternative to the previously described embodiment of the securing device according to the invention, or in particular also in combination with this variant, it is also possible to carry out the securing structure provided on the side of the base plate as a radial slot in which the securing element can be inserted.

The securing element which can be inserted into the radial slot can in particular be made of a plastic material and in that case be designed such that it comprises a base section and a blocking arm section, so that cherungselement over the base portion of the securing structure is firmly anchored so that the locking arm reliably supports the pointer.

It is possible to design the securing element such that it can be brought under the action of an overload torque in a release state. This release state can be achieved in particular by the Sperrarmabschnitt of the fuse element kinks when reaching the overload torque. It is possible to provide here a captive, for example in the form of a film hinge section by which a drop of the unlocked by bending Sperrarmabschnittes is prevented. The securing element can also be pushed radially out of the securing structure in order to bring about the release state.

Further details and features of the invention will become apparent from the following description in conjunction with the drawings. It shows:

Figure 1 is an axial sectional view for illustrating the structure of a tensioning device according to the invention with an operating sex center and a setting eccentric and a fixing device according to the invention;

Figure 2 is also an axial sectional view illustrating the

Structure according to the invention tensioning device according to a second embodiment of the invention;

FIG. 3 is a perspective view of a clamping device with a working eccentric pivoted back into a pretensioning position, to explain the securing variants "slot insertion element" and "lateral securing pin";

4 shows a perspective sketch to illustrate a further variant of a securing device according to the invention. FIG. 1 shows, in the form of an axial sectional view, an inventive eccentric tensioning device according to a first embodiment of the invention. The eccentric tensioning device comprises a setting eccentric 1, which is provided with an axial bore 2, via which the entire eccentric tensioning device can be screwed to a flange surface, in particular the end face of an internal combustion engine, via a fastening screw (not illustrated here). The adjustment eccentric 1 is seated in a hollow bolt 3, which in turn is anchored to a base plate 4. On the base plate 4, a driver portion 5 is formed, through which the base plate 4 is rotatably anchored to the counter-structure provided for receiving the eccentric clamping device.

On the hollow pin 3 sits a plain bearing bush 6, which as such a working eccentric 7 rotatably supported on the hollow pin 3. The working eccentric 7 in turn carries a roller bearing device 8, which is executed in the embodiment shown here as a double-row, sealed Ku-gellager. On the rolling bearing device 8 is seated a race 9, which as sol- rather forms a raceway outer surface 10 which rests in the installed state of the eccentric clamping device shown here on the Außenflä-che of an associated traction means of a traction mechanism. In the exemplary embodiment shown here, an inner and an outer guide ring edge 11, 12 are formed on the race 9, by means of which a certain lateral guidance is ensured for the pulling means running on the raceway.

As an alternative to the embodiment shown here, it is also possible to manufacture the race 9 directly by the outer race 13 of the rolling bearing device 8 and optionally to dispense with the guide ring edges 11, 12. The inner race 14 of the Wälzlagereinrich-device 8 may optionally be executed integrally with the working eccentric 7. In the exemplary embodiment shown here, a torsion spring device 15 generates a pivoting moment through which the working eccentric 7 can be moved. compared to the base plate 4 is biased in a certain direction of pivoting be. As a result of the pivoting moment generated by the torsion-spring device 15, the running-disk device 9, which is rotatably mounted on the working eccentric 7, is radially displaced by the pivoting of the working eccentric 7.

On the working eccentric 7, a pointer arm 16 is formed, which has a pointer tip portion 17 which, as in this illustration er-identifiable, in the radial direction over the outer peripheral region of the running ring 9 and also over the outer peripheral region of Führungsringrän-the 11, 12th protrude radially. On the base plate 4 there is likewise formed a protrusion section 4a, which protrudes radially beyond the peripheral edge region of the race 9 or the guide ring edges 11, 12.

The eccentric tensioning device shown here is characterized in that at that over the outer peripheral region of the race 9 ra-dial protruding base plate portion 4a a securing structure 18 is formed, through which the pointer arm 16 in a biasing pivot position on the base plate 4 is securable.

In the embodiment shown here, a through hole 19 is formed in the base plate portion 4a. Also in the pointer tip portion 17, a through hole 20 is formed, which in the pivoting position shown here with the through hole 19 of the base plate section 4a is aligned. The securing of the pointer arm 16 in the pivoting position shown here is accomplished by a fuse element designed as a securing element 21.

In the embodiment shown here, the securing pin 21 is designed as a bent wire part, which has a stop portion 22 through which the securing position of the here shown Sicherungszustan-the required Einsteckaxialposition is fixed. On the securing pin 21, a head section 23 is furthermore formed, through which the securing pin 21 taken and can be deducted from the holes 19, 20. In the embodiment shown here, the securing pin 21 in the region of the head portion 23 thereof is formed so that the securing pin 21 must first be pivoted by an angle of about 90 degrees until a lower grip portion 24 of the securing pin 21 is released from the guide ring edge 12 and a deduction of the securing pin 21 allows.

In the embodiment shown here, the base plate portion 4a is provided with an inwardly folded back extension 4b, through which a second through-hole 19a is formed, in which an end portion of the securing pin 21 is additionally guided radially. By this extension 4b results in an advantageous manner a particularly-viable anchoring of the securing pin 21 in the Grundplat te 4th

The fixing device shown here for fixing the working eccentric in a biasing pivot position may form the only such Fixiereinrich-tion of the eccentric clamping device. It is also possible to realize this fixing device, as indicated here, in conjunction with other fixing devices. In the exemplary embodiment shown here, a shearing structure 25 is provided by way of example in addition to the fixing device 18 realized by incorporating a securing element designed as securing pin 21. This shear structure 25 may be designed so that its carrying capacity is so high that even after unlocking the fixing device 18 is not immediately pivoting of the working eccentric relative to the base plate 4 takes place, but first an auxiliary torque must be applied, through which the pin 25a of the shear structure 25 is sheared off.

The shearing structure 25 can also serve to ensure a required basic orientation of the adjustment eccentric 1 relative to the base plate 4 or the working eccentric 7 in the delivery state of the eccentric tensioning device according to the invention. As an alternative to the embodiment shown here with a through hole 20 formed in the pointer tip section 17, it is also possible to insert the insertion pin 21 only into the bore 19 and to support the pointer tip section 17 on the securing pin 21 via a pointer tip side surface.

FIG. 2 shows a second embodiment of an eccentric tensioning device according to the invention. With regard to the mode of operation of the main components of the clamping device, the statements relating to FIG. 1 apply mutatis mutandis to this embodiment. This second embodiment differs from the variant described above in connection with FIG. 1 with regard to the design of the fixing device 18. In the variant shown here, the securing element 21 is designed in such a way that it acts as indicated by the arrow symbol P1. indicates, laterally or radially from the base plate 4 can be removed. In the base plate 4, a radial slit 26 is formed in a base plate section 4a projecting radially over the outer peripheral region of the guide ring rim 11, in which the securing element 21 is guided. In this exemplary embodiment, the securing element 21 comprises a base section 27, via which the anchoring of the securing element 21 on the base plate section 4a or in the radial slot 26 is accomplished. The securing element 21 furthermore comprises a blocking arm section 28, which as such forms a lateral contact surface which supports the pointer tip section 17.

The securing element 21 may in particular be made of a plastic material. It is possible to bring about the arming of the working eccentric 7 by either the securing element 21, as indicated here, in the direction of the arrow P1 is withdrawn radially outward. It is also possible to dimension the securing element 21 in such a way that, when a lateral force applied by the pointer tip section 17 is exceeded, it kinks or otherwise passes into a release state. In Figure 3 is further illustrated in the form of a perspective sketch, as in the inventive eccentric clamping device of the pointer tip portion 17 can be temporarily secured to the base plate portion 4a. On the one hand, the securing element 21 guided out as a plastic component can be pushed into the radial slot 26 so that the inner web 21a of the securing element 21 is received in the radial slot 26 and the blocking arm section 28 projects forward over the front side of the base plate section 4a and hereby a forms a blocking surface engageable with a side surface of the pointer tip portion. Alternatively, it is also possible to insert in the indicated here bore 19 as a locking pin executed hedging element and thereby temporarily securing the pointer tip portion 17 in the pivot position shown here.

FIG. 4 illustrates in the form of a perspective detailed sketch a further variant of the fixing device 18 of an eccentric tensioning device according to the invention. In the exemplary embodiment shown here, the fixing element 21 is designed as a swivel head element, which can be pivoted from the blocking position shown here into a release position. In the embodiment shown here, the release position is achieved by a passage slot 30 of the locking element 21 is pivoted by 90 degrees until it forms a flush with a passageway 31 structure. At the pointer tip portion 17, a follower portion descending downwardly into the pass-through path 31 is formed, which abuts on an outer peripheral surface of the securing element 21 in the position shown here. Fixing structures may be provided in the region of the securing element 21, by means of which it is ensured in a reliable manner that the securing element 21 can not unintentionally pivot back into a blocking position. The securing element 21 preferably remains in the base plate 4 and may optionally be used again in the context of carrying out maintenance work on the corresponding belt drive for fixing the pointer tip section 17 in a pretensioning pivoted position. In the belt tensioner shown in Figure 1, a bore 19 or a hole is mounted in the base plate 4 such that in this hole or in this hole a particular designed as a pin fuse element can be introduced during assembly. The pointer 16 can rest against the pin in assembly position. As a result, a rotation of the working eccentric 7 relative to the base plate 4 is prevented and the prestressing is maintained. It is also possible to provide on the pointer 16 a hole or a hole through which a pin can be inserted when Ü cover the two holes. The pin then takes over the function of anti-rotation. Another possibility is, as already mentioned in connection with FIG. 2, a molded part, which can be designed in particular as a cast part, or else a sheet metal bent part in a recess formed on the base plate 4 to which the pointer is turned to sustain the bias can support. For this purpose, the molded part is inserted or suspended in the arrowhead in the existing recess.

The rolling bearing 8 of the tensioning device is preferably designed as a radial roller bearing which consists of an inner bearing ring and an outer bearing ring and a plurality between the bearing rings in groove-shaped Laufbah- NEN rolling, held by a bearing cage in gleichmäßi-gene spaced rolling elements and axially on both sides of its rolling elements each having a seal with wel-cher trained as a grease deposit space between the bearing rings is sealed, this rolling bearing is characterized in that this is designed as a ball roller bearing, the rolling elements as ball rollers with two symmetrical of a Ball basic form ab-flattened and arranged parallel to each other side surfaces are executed. This ball roller bearing offers increased load capacity compared to a comparable ball bearing due to the higher number of rolling elements that can be mounted, as well as an enlarged grease depot due to the reduced installation space of the rolling elements. The rolling elements of the radial roller bearing designed as ball rollers are preferably designed such that they preferably have a width between their side surfaces of approximately 70% of the diameter of their ball basic shape and through which a height of approximately 80% of the diameter of the ball basic shape of the rolling elements having the distance between the concentric zueinan-arranged bearing rings initially axially "flat" inserted into the radial rolling bearing and by a corresponding rotation through 90 ° in the raceways of the bearing rings are pivotable directly form the running disk, the inner bearing ring can be formed directly by the working eccentric.

LIST OF REFERENCE NUMBERS

Adjustment eccentric 31 Continuous path

Axial bore 4a base plate section

Hollow pin P1 arrow symbol

baseplate

driver portion

plain bearing bush

working eccentric

roller bearing device

race

Race outer surface

Guide ring edge

Guide ring edge outer race inner race

torsion spring

Pointer element / pointer arm

Pointer tip section

fuse structure

Through Hole

Securing element / securing pin

stop section

header

Under handle portion

Abscherstruktur

radial slot

base section

Sperrarmabschnitt

Through slot

Claims

claims

1. eccentric tensioning device for a traction drive, comprising:

- A roller device as such a running disk (9) and a bearing for the same provided rolling bearing (8), - a working eccentric (7) for supporting the roller device such that it in accordance with a pivoting of the working eccentric (7) in one to the axis of rotation the rolling bearing (8) is displaceable in the radial direction,

- A torsion spring (15) for biasing the working eccentric (7),

- A fixing device for securing the working eccentric (7) in a mounting position in which the torsion spring (15) in a biased

State is, and

- A base plate structure (4) which is rotatably anchored to a provided for connecting the Exzenterspannvorrichtung Anflanschfläche,

- wherein the fixing device comprises a portion (4a) of the base plate structure (4) which protrudes radially over a peripheral region of the running disk (9), and wherein on this portion (4a) a securing structure (18) is formed via which also radially over the peripheral region the roller device hervororkragendes pointer element (16) can be fixed.

2. Eccentric clamping device according to claim 1, characterized in that the securing structure (18) is designed as a insertion bore (19) for receiving a securing pin designed as a securing element (21).

3. Eccentric clamping device according to claim 2, characterized in that in the pointer element (16) has a through-hole (20) is provided, which is aligned in the locking position with the insertion bore (19), so that the securing state by inserting the securing pin in the through-hole (20). and the insertion hole (19) is reached.

4. Eccentric clamping device according to claim 3, characterized in that the securing pin is designed such that this from an outside of the outer peripheral region running disk (9) lying portion of the securing structure (18) can be pulled out.

5. Eccentric clamping device according to claim 4, characterized in that the securing structure (18) is designed as a radial slot (26) in which the

Securing element (21) can be inserted.

6. Eccentric clamping device according to claim 5, characterized in that in the radial slot (26) insertable securing element (21) ckelabschnitt a (27) and a Sperrarmabschnitt (28), and that the securing element (21) via the base portion (27 ) is anchored to the securing structure (18).

7. Eccentric clamping device according to at least one of claims 1 to 6, characterized in that the securing element (21) is designed such that it can be brought under the action of an overload torque in a release state.

8. Eccentric clamping device according to at least one of claims 1 to 7, characterized in that the clamping device comprises both a locking device including the inclusion of the securing pin and the inclusion of a base portion comprising a securing element (21).

9. Eccentric clamping device according to at least one of claims 1 to 8, characterized in that on the base plate (8) has a projection (10) is formed, for the rotationally fixed anchoring of the base plate (8) on the Anflanschfläche.

10. Eccentric clamping device according to at least one of claims 1 to 9, characterized in that the pointer element (16) integral with the working eccentric (7) is executed.