Lever system

Abstract

A lever system for actuating at least one clutch, comprising at least one pivotable lever that has a certain bending stiffness. The lever has at least one flexurally elastic zone which is designed and/or arranged in such a way that the bending stiffness of the lever varies in accordance with an actuation path of the clutch.

Claims

1. A lever system for actuating at least one clutch, comprising: at least one pivotable lever having a first flexural rigidity, wherein said lever has at least one flexurally elastic region, the at least one flexurally elastic region including a second flexural rigidity and is designed and/or arranged in such a way that said flexural rigidity of said lever varies as a function of an actuating path of said clutch; a carriage positioned on a bottom surface of the lever, wherein the carriage is arranged at a first end of the lever and a second end of the lever, opposite the first end, is pivotably fixed at a pivot.

2. The lever system recited in claim 1, wherein said lever has a negative rigidity gradient across said actuating path of said clutch.

3. The lever system recited in claim 1, wherein an actuating contact region is arranged between the pivot and a contact region for an upper roller of the carriage.

4. The lever system recited in claim 3, wherein a cam track is formed in said contact region for said upper roller on said lever in such a way that said actuating path of said clutch increases as a distance between said roller and a clutch axis increases.

5. The lever system recited in claim 3, wherein said flexurally elastic region is arranged between said actuating contact region and said pivot.

6. The lever system recited in claim 3, wherein said flexurally elastic region extends from said pivot beyond said actuating contact region.

7. The lever system recited in claim 3, wherein said flexurally elastic region is implemented by a counter-spring on which said pivot is mounted.

8. The lever system recited in claim 1, wherein said lever for actuating two partial clutches of a twin clutch is combined with a lever actuator.

9. An actuating device for actuating at least one clutch comprising said lever system as recited in claim 1.

10. A clutch device comprising at least one clutch that has a regressive characteristic map and is actuated by said lever system as recited in claim 1.

11. The lever system recited in claim 1, wherein the second flexural rigidity is different than the first flexural rigidity.

12. The lever system recited in claim 1, wherein the second flexural rigidity is less than the first flexural rigidity.

13. A lever system for actuating at least one clutch, comprising: at least one pivotable lever having a first flexural rigidity and a contact area to output an actuation force of said lever, wherein said lever has at least one flexurally elastic region, the at least one flexurally elastic region including a second flexural rigidity and is designed and/or arranged in such a way that said flexural rigidity of said lever varies as a function of an actuating path of said clutch, said lever pivotably secured at a first end of said lever; wherein, the contact area of said lever is arranged on said lever at a first distance from said first end of said lever, and said flexurally elastic region is arranged on said lever at a second distance from said first end of said lever.

14. The lever system recited in claim 13, wherein said first distance is greater than said second distance.

15. The lever system recited in claim 13, wherein said first distance is less than said second distance.

16. The lever system recited in claim 13, wherein said first distance is equal to said second distance.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The invention will now be described in greater detail by reference to the accompanying figures, in which the figures represent the following:

(2) FIG. 1 is a simplified representation of a lever system of the invention having an elastic region;

(3) FIG. 2 illustrates a lever system similar to the one shown in FIG. 1 comprising a counter-spring rigidity associated with a pivot of the lever system;

(4) FIG. 3 illustrates a lever system similar to the one shown in FIG. 1 comprising a larger flexurally elastic region;

(5) FIG. 4 illustrates an embodiment of the lever system shown in a simplified way in FIG. 3;

(6) FIG. 5 illustrates the lever system of FIG. 4 with an additional lever actuator;

(7) FIG. 6 illustrates a Cartesian coordinate system with a characteristic map of the lever system of FIG. 4; and,

(8) FIG. 7 illustrates a Cartesian coordinate system with a characteristic map that incorporates a counter-spring.

DETAILED DESCRIPTION OF THE INVENTION

(9) At the outset, it should be appreciated that like drawing numbers on different drawing views identify identical, or functionally similar, structural elements of the invention. While the present invention is described with respect to what is presently considered to be the preferred aspects, it is to be understood that the invention as claimed is not limited to the disclosed aspects.

(10) Furthermore, it is understood that this invention is not limited to the particular methodology, materials and modifications described and, as such, may, of course, vary. It is also understood that the terminology used herein is for the purpose of describing particular aspects only, and is not intended to limit the scope of the present invention, which is limited only by the appended claims.

(11) Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood to one of ordinary skill in the art to which this invention belongs. Although any methods, devices or materials similar or equivalent to those described herein can be used in the practice or testing of the invention, the preferred methods, devices, and materials are now described.

(12) FIGS. 1 to 3 are simplified representations of various exemplary embodiments of lever system 1, 21, and 31 of the invention. In the drawings, identical or similar elements are indicated by identical reference symbols. The first few paragraphs that follow will describe the aspects lever systems 1, 21, and 31 have in common. Then the differences between the individual exemplary embodiments will be explained.

(13) Lever system 1, 21, and 31 comprises lever 4 that is arranged in a hinge-like manner to pivot on a (non-illustrated) support structure as indicated by pivot 5. Due to its pivotal or hinge-like arrangement, lever 4 may be referred to as a hinge lever.

(14) Pivot 5 is formed on one end of lever 4. The opposite end of lever 4 rests on carriage 8. As indicated by double-headed arrow 10, carriage 8 is movable back and forth in a horizontal direction. For this purpose, rollers are provided on the bottom of carriage 8 to roll on a corresponding track in a horizontal direction.

(15) A corresponding cam track of lever 4 rests on an upper roller of carriage 8. The shape of the cam track formed on lever 4 is selected such that as indicated by double-headed arrow 12, an actuating contact region of the lever moves upward when carriage 8 moves away from pivot 5.

(16) Double-headed arrow 12 is located on line of action 13 of the actuation force of the clutch. When carriage 8 moves towards pivot 5, lever 4 with its actuating contact region moves downward.

(17) Carriage 8 with the rollers and the cam track on lever 4 form a cam mechanism integrated in lever system 1, 21, and 31. The opposing arrangement of pivot 5 and carriage 8 or rather the cam mechanism causes an actuation three of the clutch, also referred to as an engagement force, to be distributed between carriage 8 and pivot 5. As a result, the overall force for actuating the clutch may be lower than in the case of a lever actuator as described in the international patent application publication no. WO 2008/154896 A1, for instance.

(18) In lever system 1 shown in FIG. 1, double-headed arrow 16 indicates distance R.sub.R between carriage 8 and line of action 13 of the actuation force. Double-headed arrow 17 indicates distance L.sub.1 between line of action 13 and flexurally elastic region 14. Further double-headed arrow 18 indicates distance L.sub.0 between line of action 13 and pivot 5.

(19) Flexurally elastic region 14 has flexural rigidity c.sub.T indicated in newton meters per rad. Based on flexural rigidity c.sub.T, the effective actuation rigidity or engagement rigidity of lever 4 is calculated as follows:

(20) $c_{\mathrm{eff}}=c_T\left(\frac{1}{R_R+L_1}+\frac{1}{L_0-L_1}\right)\left(\frac{1}{R_R}+\frac{\frac{L_1}{R_R}+1}{L_0-L_1}\right)\mathrm{for}{L}_1\ge 0$$c_{\mathrm{eff}}=c_T\left(\frac{1}{R_R+L_1}+\frac{1}{L_0-L_1}\right)\left(\frac{1}{L_0}+\frac{L_0-L_1}{L_0\left(R_R+L_1\right)}\right)\mathrm{for}{L}_1\le 0$

(21) The effective rigidity progressively diverges the closer flexurally elastic region 14 is to carriage 8. If L.sub.1 equals zero, i.e. if flexurally elastic region 14 is arranged in the region of the intersection between line of action 13 and lever 4, i.e. directly beneath the engagement system, the equation reads:

(22) $c_{\mathrm{eff}\_1}={c_T\left(\frac{1}{R_R}+\frac{1}{L_C}\right)}^2$

(23) If the position of carriage 8 (R.sub.R) varies between 40 and 80 millimeters and L.sub.1 equals zero, the effective rigidity changes by a factor nine to four.

(24) The internal rigidity or elasticity of lever 4 causes the effective engagement rigidity of lever 4 to decrease as the distance of the point of contact on the upper roller of carriage 8 increases. Thus, an increasing axial distance between the upper roller of carriage 8 and pivot 5 results in a decreasing rigidity of lever system 1 as the engagement or actuating path increases.

(25) In lever system 21 shown in FIG. 2, flexurally elastic region 24 of lever 4 is represented by counter-spring 25, which has a defined rigidity, also referred to as counter-spring rigidity. Counter spring 25 is arranged directly beneath pivot 5.

(26) Double-headed arrow 26 indicates distance R.sub.R between carriage 8 and line of action 13. Double-headed arrow 27 indicates sum R.sub.R plus L.sub.0. For lever system 21 shown in FIG. 2, due to the translation of the counter-spring rigidity on lever 4 supported on the upper roller as a fixed point, the effective engagement rigidity of lever 4 is calculated as follows:

(27) $i=\frac{R_R}{R_R+L_0}$

(28) The effective rigidity in the actuating region, i.e. in the intersection between line of action 13 and lever 4, is calculated as follows:

(29) $c_{\mathrm{eff}\_2}=\frac{c_G}{i^2}$

(30) If the counter-arm of lever 4 has length L.sub.0 of 80 millimeters and the roller path of carriage 8 described above is between 40 and 80 millimeters, for example, the effective rigidity likewise varies by a factor nine to four.

(31) In lever system 31 shown in FIG. 3, lever 4 has flexurally elastic region 34 that is significantly larger than flexurally elastic region 14 of lever system 1 shown in FIG. 1. Flexurally elastic region 34 on lever 4 extends from pivot 5 beyond the actuating contact region of lever 4. This is a simple way of allowing the lever to be sufficiently deformed without exceeding tension limits of the material lever 4 is made of.

(32) FIG. 4 is a perspective view of an embodiment of lever system 41 including lever 44. On one end, lever 44 has a curved section formed like a depression to indicate pivot 45. Carriage 48 is associated with the opposite end of lever 48. Lever 48 is movable on base plate 50. Roller 51 is supported for rotation on carriage 48. Lever 44 has a cam track that rests on roller 51. Two further rollers 52, 53 are provided for the carriage to be movable on base plate 50.

(33) Approximately at the center on its upper side, lever 44 has actuating contact region 55. Actuating contact region 55 comprises two contact surfaces 56, 57. In the assembled state of lever system 41, these contact surfaces 56, 57 are in contact with a (non-illustrated) actuation bearing or apply bearing of the clutch. Between contact surfaces 56, 57, lever 44 has a through-hole for example, for a transmission shaft to pass through.

(34) FIG. 5 is a perspective view of lever system 41 with lever 44 of FIG. 4 advantageously combined with lever actuator 58. The illustrated combination simplifies the actuation of two partial clutches in a specific twin clutch to a considerable extent.

(35) FIGS. 6 and 7 illustrate two Cartesian coordinate systems with x-axis 61 and y-axis 62. Y-axis 62 shows the engagement or actuation force of a clutch that is actuated with the aid of a lever system as described above. X-axis 61 shows the associated actuating or engagement path.

(36) The Cartesian coordinate system represents nominal characteristic lines 65, 75 of the clutch. The dotted lines above and the dashed lines below nominal characteristic lines 65, 75 of the clutch indicate maximum and minimum characteristic lines of the clutch.

(37) The coordinate system shown in FIG. 6 illustrates characteristic map 68 of the lever system shown in FIG. 4. The coordinate system shown in FIG. 7 indicates characteristic map 78 additionally factoring in a counter-spring such as counter-spring 25 shown in FIG. 2.

(38) Thus, it is seen that the objects of the present invention are efficiently obtained, although modifications and changes to the invention should be readily apparent to those having ordinary skill in the art, which modifications are intended to be within the spirit and scope of the invention as claimed. It also is understood that the foregoing description is illustrative of the present invention and should not be considered as limiting. Therefore, other embodiments of the present invention are possible without departing from the spirit and scope of the present invention.

LIST OF REFERENCE SYMBOLS

(39) 1 Lever system 4 Lever 5 Pivot 8 Carriage 10 Double-headed arrow 11 Double-headed arrow 13 Line of action 14 Flexurally elastic region 16 Double-headed arrow 17 Double-headed arrow 18 Double-headed arrow 21 Lever system 24 Flexurally elastic region 25 Counter-spring 26 Double-headed arrow 27 Double-headed arrow 31 Lever system 34 Flexurally elastic region 41 Lever system 44 Lever 45 Pivot 48 Carriage 50 Base plate 51 Roller 52 Roller 53 Roller 55 Actuating contact region 56 Contact surface 57 Contact surface 58 Lever actuator 61 X axis 62 Y axis 65 Characteristic line 68 Characteristic map 75 Characteristic line 78 Characteristic map