WO2011003383A1

WO2011003383A1 - Idler, especially for a continuously variable transmission comprising a crank mechanism

Info

Publication number: WO2011003383A1
Application number: PCT/DE2010/000710
Authority: WO
Inventors: Laszlo Man
Original assignee: Schaeffler Technologies Gmbh & Co. Kg
Priority date: 2009-07-06
Filing date: 2010-06-21
Publication date: 2011-01-13
Also published as: DE102010024447A1; JP2012532292A; JP5822827B2; DE112010002861A5

Abstract

The invention relates to an idler, especially for a continuously variable transmission comprising a crank mechanism. Said idler includes an inner ring (1), an outer ring (2) that can be rotated relative to the inner ring (1) in at least one rotational direction and is radially arranged around the inner ring, multiple clamping elements (3) which are arranged between the inner ring and the outer ring (2), and at least one clamping element spring system for applying a spring force of a spring to the clamping elements. The idler of the invention is characterized in that when rolling, the clamping elements (3) are guided on the outer ring (2) essentially along a contact zone corresponding to the logarithmic spiral representing torque transmission.

Description

Freewheel, especially for a crank-CVT transmission

The present invention relates to a freewheel, in particular for a crank-CVT transmission.

A CVT is a uniformly translating gearbox in which the ratio of the speeds of the driving and the driven shafts, the ratio in a certain range can take an infinite number of steps. This can also include the standstill or the reversal of the direction of rotation of a shaft. The transmission of the movement takes place via a non-fixed coupling of components whose geometries determine the gear effect according to the lever principle. A ratio change is achieved by changing these component geometries, but at the same time can not be done without changing the geometries at the point of component coupling.

Many freewheel devices for crank-CVT transmission have for this purpose clamp bodies which are arranged between an inner ring formed by a region of the output shaft and an outer ring. The surfaces of the outer ring and the inner ring are matched to one another such that the clamping body can block this rotation in a Relatiwerdrehrichtung between inner ring and outer ring, so that the outer ring and the inner ring are rotated together. In the other Relativverdrehrichtung between the outer ring and the inner ring no blocking effect is effected by the clamping body. The individual clamping body are acted upon in the reverse direction, which can be done by at least one spring element. Further, freewheel devices for a transmission, in particular for a crank-CVT transmission of a motor vehicle are known, which have held between an outer ring and an inner ring in a cage Kiemmkörper. In each case, a clamping body can be pressed by an energy store against the inner ring with a relatively large contact pressure. By a mechanism of the clamping body in the release direction or in the clamping direction can be set, wherein the energy storage is dimensioned so that it generates a relatively small contact force for setting up the clamping body at a relatively large contact force. A crank CVT transmission is known for example from EP 1 650 071 A2. On an input shaft which can be driven by a motor and which forms a driving shaft with respect to the gear, an adjustable eccentric drive arrangement with eccentric components is provided, which is connected via connecting rod-like connecting elements to a driven shaft which, with respect to the gearbox, has an output or output shaft. forms a drive shaft. By transmitting the stroke of the connecting elements by means of freewheel devices on the driven shaft and thus the output side of the transmission, the driven shaft is driven to rotate. The freewheel devices are provided between the connecting rod-like connecting elements and the driven shaft. The individual freewheel units 10 have clamping bodies which are formed by rollers. The clamping action is thus achieved as a "roller freewheel through a profiled inner raceway (polygonal profile 50) in conjunction with rollers as a clamping body 42. Alternatively, a sprag freewheel having a smooth inner and outer raceway but profiled clamping bodies can be provided The inner surface of the outer ring and the outer surface of the inner ring are matched to one another such that the clamping body can block this rotation, at least in a direction of relative rotation between inner ring and outer ring, so that both rings Either no blocking effect is generated by the clamping bodies in the other direction of relative rotation between the two rings, or so-called reversible freewheels are provided, which in addition to a neutral position in which they rotate relative to the Innenri Ngs and the outer ring allow two blocking positions, in which the two rings block in a first and second relative rotational direction and thus are rotated together in a first and second rotational direction. Through this switchable freewheel devices, the direction of rotation of the shaft can be changed in the transmission and, for example, a reverse gear can be realized. The rollers are pressed by a spring as a pressing element in the gap between the inner star and the outer ring, whereby the rollers are held as clamping elements in contact with the outer ring and inner star. For the roles while a cage is provided. The spring may be formed as a leg spring, wherein the switching is achieved in that the spring or the spring leg executes a pivoting movement, whereby the role is pressed by the associated right flank on the left flank.

From DE 102 43 533 A1 a switching device is also known, which serves to switch the blocking function of the freewheel. This switching device comprises a plurality of switching units, which are each arranged between adjacent rotationally symmetrical clamping bodies. The switching units are synchronously actuated and have switching means, each having a rotatable disk-shaped area and a, preferably made of a profiled bar, profiled area. At the profiled area a leg spring is provided, which is clamped between the profiled area and a clamping body. For this purpose, the leg spring has a leg which has a clamping body can act in the corresponding blocking direction. The leg spring and the profiled areas are arranged eccentrically with respect to the axis of rotation of the disk-shaped area, so that upon a rotation of the disk-shaped area a circumferential displacement of the leg spring and the profiled areas takes place. By rotating the disk-shaped regions by approximately 180 °, the tension direction or the direction of force of the leg spring changes. In this way, a Zugbetrieb the operation of a motor vehicle or a corresponding for a reverse drive of the motor vehicle relative position can be adjusted.

The sprags of this freewheel devices are subjected to a constant springing and damping, which higher for higher speeds Anfederungs- and damping forces must be installed, which act unchanged even at low speeds, whereby a loss of efficiency is recorded. Furthermore, additional parts for the damping are required in these solutions, resulting in an increased design effort.

Object of the present invention is to develop a freewheel, in particular a freewheel for a crank-CVT transmission, the springing and damping is dynamically dependent (speed-dependent) can be changed.

This object is achieved with the characterizing features of the first claim. Advantageous embodiments emerge from the subclaims.

The freewheel, in particular for a crank-CVT transmission with an inner ring, has a relative to the inner ring in at least one rotational direction rotatable outer ring, which is arranged radially around the inner ring around, and a plurality of clamping body, which are arranged between the inner ring and the outer ring and has at least one Klemmkörperanfed- tion for acting on the clamping body with a spring force of a spring, according to the invention the clamping body are guided on the outer ring during rolling substantially on one of the logarithmic spiral for transmitting torque corresponding contact zone. As a result, the clamping bodies are guided during rolling without slipping on the surface of the logarithmic spiral (torque transmission), whereby the springing of the dynamics is proportional. The outer ring has in its contact zone with the clamping body to a shape which is formed substantially in the manner of a cycloid. The clamp body or bodies are thereby accelerated back and forth with the outer ring in the circumferential direction. For this purpose, the clamping body advantageously has two protrusions / arms facing away from one another in the direction of rotation, which can be pressed radially onto the contact zone with a contact force during an acceleration, wherein the contact force is essentially proportional to the angular acceleration of the outer ring.

The radial positions of the projections (arms) are preferably arranged so that the contact force to the outer ring generates a torque about the center of gravity of the clamping body by its inertia.

Preferably, each clamping body sits with its projections / arms having region in a recess of the outer ring, wherein in the recess, the contact zone of the outer ring is formed and the recess tapers in the direction of the inner ring.

If a positive acceleration acts on the outer ring, a positive torque is transmitted to the clamping bodies and the clamping bodies are turned out of their contact gap with respect to the inner ring and the outer ring against the spring force of the spring. If the outer ring accelerates negatively, a negative torque acts on the clamping body and these are pressed back against the inner ring, whereby a torque between the inner and outer ring transmitted.

The spring force of the spring acts in particular on the first in the positive direction of rotation arranged projection / arms of the clamp body.

The first contact surface pointing in the direction of the inner ring and a second contact surface of the clamping body pointing in the direction of the contact zone of the outer ring are convexly curved at least in some regions in order to realize a good rolling movement.

In particular, the pointing in the direction of the outer ring second contact surface of the clamping body in the region of the first projection is convexly curved, since in this area a rolling movement on the outer ring, wherein in the region of the second projection (Ärmchens), the contact surface is substantially planar, as at a maximum swing movement of the clamp body in the positive direction of this area is applied to a substantially planar region of the contact zone.

The clamping body preferably tapers in cross-section according to the projections (arms) in the direction of its center of gravity and then widens again in the direction of the inner ring.

The spring acting against the first projection of the clamping body is in particular a leg spring whose leg is attached to the outer ring.

The relatively complicated shape of the outer ring can be simplified by the use of a cage in which the contact zones having recesses are arranged.

Due to the own mass of the clamp body creates a contact force to the outer ring to the arms. This force is proportional to the angular acceleration of the outer ring at any time and is therefore dependent on the dynamics. The radial positions of the arms are chosen in particular so that the contact force generates a torque about the center of gravity of the clamping body by its inertia.

If the outer ring is accelerated after the clamping operation against the spring in the positive direction, the clamping body experiences a torque which rotates the clamping body out of the contact gap to the inner and outer ring, whereby the clamping body of inner and outer ring lifts (good efficiency). Thereafter, the outer ring is accelerated in the negative direction, whereby the clamping body gets a negative torque and thereby pressed against the inner ring and against the contact zone of the outer ring, whereby a torque between the inner and outer ring is transferable. The gripping process is actively supported, because in addition to the basic suspension and this negative torque of the clamp body helps displace the lubricant film between the clamp body and the inner ring. The springing is proportional to the dynamics. The lever arm of the contact force to the center of gravity should not be too large, so that the friction losses in the positive acceleration are not too high.

The movement of the clamping body in the region of the contact zone of the outer ring also generates a frictional force which dampens the oscillating movement of the clamping body. This friction can be enormous at high dynamics, creating a very good damping of the clamp body is expected. The position of the lateral clamping body sleeves must be selected so that the friction is always overcome by the resulting torque.

The invention will be explained in more detail with reference to an embodiment and associated drawings. Show it:

1 shows a section of the cross section of a freewheel through a arranged between inner ring and outer ring clamp body,

FIG. 2 shows the three-dimensional representation of a clamping body,

3 shows a perspective view of an outer ring,

FIG. 4 shows the acceleration forces on the clamping body with positive acceleration,

FIG. 5 shows the acceleration forces on the clamping body with positive acceleration,

Figure 6 shows the freewheel at different operating positions.

In Figure 1, the section of the cross section of a freewheel through a disposed between inner ring 1 and outer ring 2 clamping body 3 is shown in the nominal position. The clamping body 3 has in the direction of the outer ring 2 two extending in the direction of rotation projections (arms) 3.1 and 3.2. Towards its center of gravity S, the clamping element 3 tapers and widens again in the direction of the inner ring. On the inner ring 1, the clamping body 3 engages with a first contact surface 3a and on the outer ring with a second contact surface 3b. The clamping body 3 sits with his arms in a recess 2.1 of the outer ring 2. In this recess 2.1, a contact zone 2a is formed, on which the contact surface 3a engages.

On the first arm 3.1 acts a spring 4, which is designed in the form of a leg spring and the legs 4.1 bears against the pointing in the direction of the inner ring 1 underside of the first arm 3.1 under tension. The leg spring 4 is attached by means of a pin 4.2 on the outer ring 2. The recess 2.1 has a base 2a, a first side surface 2b on the side of the first arm 3.1 and a second side surface 2c on the side of the second arm 3.2. The side surfaces 2a and 2b converge towards the inner ring 1 toward each other. The base 2a and the side surfaces 2b and 2c of the recess 2.1 are curved convex. The second contact surface 3b of the clamping body 3 thereby rolls on the contact zone (recess 2.1) of the outer ring 2 such that a cycloidal movement results and the clamping bodies are guided on the outer ring during rolling essentially on a contact zone corresponding to the logarithmic spiral for transmitting torque. The arms 3.1, 3.2 are in the position shown in Fig. 1 with their outwardly facing rounded outer sides 3.1 ', 3.2' to the side surface 2b and 2c of the recess 2.1 at.

FIG. 2 shows the three-dimensional representation of a clamping body which has a first arm 3.1, a second arm 3.2 and a second contact surface 3b pointing upwards on this side. Each arm has an outwardly directed rounded outside 3.1 ', 3.2'. Opposite the second contact surface 3b, a first curved contact surface 3a is formed. In its center, the clamping element in the direction of its center of gravity S on a non-designated constriction.

The perspective view of an outer ring is shown in FIG. The outer ring 1 has on its inner contour a plurality of distributed over the circumference recesses 2.1, in which the clamping elements not shown here are added. On both sides of each recess two axially offset receptacles 5 are provided, on which the spring 4 is attached.

FIG. 4 schematically shows the acceleration forces on the clamping body 3 with positive acceleration and FIG. 5 with negative acceleration. 4, the outer ring moves in the direction of the arrow with the + and thus the clamping body 3 clockwise about its center of gravity S. The first arm 3.1 acts against the leg 4.2 of the spring 4 and the clamping body 3 dissolves with its contact surfaces 3a, 3b of outer and inner ring 2, 1, whereby a clearance between the outer and inner ring 2, 1 is ensured, however, wherein a damping is generated. In a negative acceleration of Fig. 5, the outer ring 2 moves according to the arrow with - in the opposite direction, whereby the clamping body 3 is pivoted counterclockwise about its center of gravity S and with its contact surfaces 2a and 2b against outer and inner ring. 2 , 1 is pressed, whereby torques between the outer and inner ring 2, 1 are transferable. When swiveling movement of the clamp body 3 slides the rounded first outer side 3.1 'on the first side surface 2b of the recess 2.1 and the rounded second outer side 3.2' on the second side surface 2c of the recess 2.1 along and the second contact surface 3b of the clamping body 3 rolls on the base 2a of the recess 2.1.

Furthermore, the first contact surface 3 a of the clamping body 3 rolls on the outer diameter of the inner ring 1.

The freewheel at different operating positions is shown in the individual images a) to d) of FIG. 6, a) shows the nominal position of the clamping body 3, which has already been described in FIG. 1, b) shows the damping position at which the clamping bodies 3 was pivoted so that the second arms 3.2 rests against the base 2a of the recess 2.1 of the outer ring 2 and the arms 3.1 was pivoted against the spring force of the spring 4 in the direction of the inner ring 1, c) shows a position of the clamping body 3 for transmitting a middle Momentes and d) the position for transmission of the maximum torque. In d), the first arm 3.1 of the clamping body 3 rests against the base surface 2.a of the recess 2.1 of the outer ring 2, and the second arm 3.2 has been tilted in the direction of the inner ring 1.

With the solution according to the invention, a dynamic-dependent springing and damping is achieved and the gripping process is actively supported (FIGS. 4 and 5), since apart from the basic application, this torque also helps to displace the lubricant film between the clamping body and the inner ring. The springing is proportional to the dynamics. The lever arm of the contact force to the center of gravity should not be too large, so that the friction losses in the positive acceleration are not too high.

LIST OF REFERENCES

1 inner ring

2 outer ring

2.1 recess

2a base area

2b first side surface

2c second side surface

3 clamp body

3.1 first arm (lead)

3.1 'outside of the first little jar

3.2 second arm (lead)

3.2 'outside of the second Ärmchen 3a first contact surface

3b second contact surface

4 spring

4.1 Leg of the spring 4th

4.2 pen

5 receptacle for the spring 4

S focus

Claims

claims

1. freewheel, in particular for a crank-CVT transmission with an inner ring (1),

a relative to the inner ring (1) in at least one rotational direction rotatable outer ring (2) which is arranged radially around the inner ring (1) around, a plurality of clamping bodies (3) which are arranged between the inner ring (1) and the outer ring (2) and at least one Klemmkörperanfederung for acting on the clamping body (3) with a spring force of a spring (4), characterized in that the clamping body (3) on the outer ring (1) during rolling substantially at one of the logarithmic spiral for torque transmission corresponding contact zone are performed.

2. freewheel according to claim 1, characterized in that the outer ring (2) in the contact zone with the clamping body (3) has a shape which is formed substantially in the manner of a cycloid.

3. freewheel according to claim 1 or 2, characterized in that the clamping body (3) with the outer ring (2) are accelerated in the circumferential direction back and forth.

4. Freewheel according to one of claims 1 to 3, characterized in that the clamping body (3) in the direction of the outer ring (2) has two circumferentially facing away from each other projections / arms (3.1, 3.2), which at an acceleration radially to the contact zone can be pressed with a contact force.

5. freewheel according to one of claims 1 to 4, characterized in that the contact force is substantially proportional to the angular acceleration of the outer ring (2).

6. freewheel according to one of claims 1 to 5, characterized in that the radial positions of the arms (3.1, 3.2) are arranged so that the contact force generates a torque about the center of gravity (S) of the clamping body (3) by its inertia.

7. freewheel according to one of claims 1 to 6, characterized in that each

Clamping body (3) with its projections / arms having region in a recess (2.1) of the outer ring (2) is arranged, wherein in the recess, the contact zone of the outer ring (2) is formed.

8. freewheel according to one of claims 1 to 7, characterized in that the recess (2.1) tapers in the direction of the inner ring (1).

9. freewheel according to one of claims 1 to 8, characterized in that at a positive acceleration of the outer ring (2) has a positive torque on the clamping body (3) and the clamping body (3) against the spring force of the spring (4) from her Contact gap to the inner ring (1) and the outer ring (2) are turned out and that at a negative acceleration of the outer ring (2) a negative torque acts on the clamping body (3) and these are pressed against the inner ring (1) again.

10. freewheel according to one of claims 1 to 9, characterized in that the spring force of the spring (4) acts on the first in the positive direction of rotation arranged jump / arms (3.1) of the clamping body (3).

11. freewheel according to one of claims 1 to 10, characterized in that in the direction of the inner ring (1) facing first contact surface (3a) and in the direction of the outer ring (2) facing the second contact surface (3b) of the clamping body (3) at least partially curved convexly.

12. freewheel according to one of claims 1 to 11, characterized in that in the direction of the outer ring (2) facing the second contact surface (3b) of the clamping body

(3) is convexly curved in the region of the first projection (arm) (3.1) and is substantially flat in the region of the second projection (sleeve) (3.2).

13. freewheel according to one of claims 1 to 12, characterized in that the

Clamping body (3) tapers in cross-section after the projections (arms) in the direction of its center of gravity (S) and then widens again in the direction of the inner ring (1).

14. freewheel according to one of claims 1 to 13, characterized in that the spring

(4) is a leg spring whose legs (4.1) acts against the first projection (3.1) of the clamping body (3) and which is attached to the outer ring (2).

15. freewheel according to one of claims 1 to 14, characterized in that the contact zones having recesses (2.1) are arranged on a cage connected to the outer ring.