EP2002147A1

EP2002147A1 - Torque sensing device for a taper disk wraparound drive

Info

Publication number: EP2002147A1
Application number: EP07721976A
Authority: EP
Inventors: Wolfgang Gantner; Andreas GÖTZ; Eugen Kremer
Original assignee: LuK Lamellen und Kupplungsbau Beteiligungs KG; LuK Lamellen und Kupplungsbau GmbH
Current assignee: Schaeffler Buehl Verwaltungs GmbH; LuK Lamellen und Kupplungsbau GmbH
Priority date: 2006-03-24
Filing date: 2007-03-05
Publication date: 2008-12-17
Also published as: WO2007110026A1; DE112007000502A5; JP2009531610A; KR20080104021A; CN101410650A

Abstract

A torque sensing device for a taper disk wraparound drive comprises a ramp face which is rigidly connected to a shaft of a taper disk pair, a further ramp face which is rigidly connected to a sensing piston which engages around the shaft and is axially moveable and rotatable relative to the shaft, which ramp faces are designed such that, in the event of a change in the torque acting between the sensing piston and the shaft, the axial position of the sensing piston is varied by means of balls, which are arranged between the ramp faces, rolling on the ramp faces, and a guide face which is rigidly connected to a moving disk, against the radial inner side of which guide face the balls bear, wherein the moving disk is rotationally fixedly and axially moveably connected to the shaft and, with a hydraulic pressure which is dependent on the axial position of the sensing piston, is forced against a fixed disk which is rigidly connected to the shaft, and the form face is shaped such that the radial spacing between the balls and the axis of the shaft is dependent on the axial spacing between the moving disk and the fixed disk, wherein the guide face is designed such that the contact points of in each case one ball with the ramp faces, the contact point of said ball with the guide face, and the central point of said ball are situated in a radially-aligned plane.

Description

Torque sensing device for a cone pulley wrap

The invention relates to a torque sensing device for a cone pulley wrap transmission.

Cone pulley, as used for example in motor vehicles, generally contain two pairs of conical disks, which are wrapped by a belt, for example, a link chain, wrapped. By opposing change in the distance between the conical disks of each conical disk pair, the transmission ratio can be changed continuously.

Advantageously, a pair of conical disks, preferably the drive side, includes an integrated torque sensor with which the torque acting on a drive motor is detected and a contact pressure between the conical disks of the associated disk pair is changed in accordance with the torque.

Such conical-pulley transmission with integrated torque sensor are described, for example, in DE 42 34 294 A1, DE 19 54 644 A1, DE 40 26 683, DE 195 45 492 A1 and DE 199 51 950 A1.

4 shows a cross section through a drive-side part of a conical-disk drive transmission. On an input shaft 10, which is formed integrally with a fixed disk, not shown, is axially displaceable, but rotatably connected to the input shaft, a spacer plate 14 is arranged.

At the rear of the spacer plate 14, a cylindrical ring 16 is rigidly fixed in the radially outer region with two radially spaced walls in which a piston 18 operates, so that according to the Fig. Right side of the piston 18, a first pressure chamber 20 is formed by formed in the travel plate 14 radial holes 22, an annular space 24 between the washer 14 and the shaft 10 and formed in the shaft 10 radial bore 26 and axial bore 28 can be acted upon by hydraulic pressure, which is variable for a translation adjustment. The overall annular piston 18 is rigidly connected to a generally cup-shaped support ring 30, which in turn is rigidly connected to the input shaft 10. At the front end of the support ring 30 ramp surfaces 32 are formed.

Further, within the support ring 30, a generally annular sensing piston 36 is arranged to be axially displaceable while sealing against the peripheral surface of the input shaft 10 and an inner circumferential surface of the support ring 30. The sensing piston 36 is formed with a projection directed toward the travel disc 14, on the rear side of which ramp surfaces 38 are formed, which form counter surfaces to the ramp surfaces 32. Between the ramp surfaces 32 and 38 are rolling elements, in the example shown balls 40, respectively.

Between the sensing piston 36 and the travel plate 14, a second pressure chamber 42 is formed, which is acted upon by the input shaft 10 leading supply line 44 with hydraulic pressure, wherein the hydraulic fluid via a likewise formed in the input shaft 10 derivative 46 can be derived.

The effective cross section of the leading into the second pressure chamber inlet opening 48 is determined by the axial position of the spacer plate 14. The effective cross section of the outgoing from the second pressure chamber 42 discharge opening 50 is determined by the position of the sensing piston 36. The sensing piston 36 protrudes with circumferentially spaced axial arms 52 through recesses of the support ring 30 therethrough. The radial outer surfaces of the arms 52 are provided with axially and radially directed teeth, which are in engagement with an internal toothing of an input gear 54, which is mounted by means of a bearing 8 axially substantially immovably on the input shaft 10.

Radially within the rigidly connected to the washer 14 cylinder ring 16, a ring member 56 is rigidly connected to the cylinder ring 16, the inside of which forms a guide surface 58 against which the balls 40 and which limits the radial outward movement of the balls 40.

The structure and function of the arrangement described so far are known per se and are therefore explained only briefly:

In the case of torque acting on the sensing piston 36 from the rotationally driven input gear 54, this torque is transmitted via the ramp surfaces 38, the balls 40 and the ramps. surfaces 32 on the support ring 30 and thus the shaft 10 transmitted. The ramp surfaces are designed such that the sensing piston 36 moves to the right with increasing torque as shown in FIG. 1, so that the discharge opening 50 is increasingly closed. With decreasing effective size of the discharge opening 50, the pressure in the second pressure chamber 42 increases, so that acts on the travel plate 14 a dependent on the input torque contact pressure. When far away to the left shifted windshield 14 (maximum underdrive of the transmission), the supply port 48 is closed, so that the second pressure chamber 42 is depressurized. The fact that the effective radius of the guide surface 58 decreases in an adjustment of the spacer plate 14 of FIG. 5 to the right, the system shifts between the balls and the ramp surfaces with increasing displacement of the washer 14 to the right radially inward, whereby the pressure in the second Pressure chamber 42 is additionally modulated depending on the translation, since the slope of the ramp surfaces depends on the radial distance of the contact points between the balls and the ramp surfaces of the axis of the input shaft 10. The slope of the wedge surfaces is generally radially inward greater than radially outward.

The known, in particular by the sensing piston 36, the ramp surfaces 32 and 38 and the guide surface 58 and the balls 40 formed torque sensing device has the following characteristics:

- With increasing speed of the input shaft 10 acts on the balls 40 an increasing centrifugal force, which is generally not completely taken over by the reaction forces of the ramp surfaces and the guide surface, whereby the pressure in the second pressure chamber 42 is speed-dependent. This can cause slippage of the belt pulley or overstress or even hysteresis.

- When only dependent on the distance from the axis of the input shaft 10 slope (radial dependence) of the ramp surfaces in the circumferential direction, the normal to the rolling surface on which the balls roll on the ramp surfaces, a radial component. Because of this, the center of the sphere and the point of contact between the sphere and the ramp are at different radii. This difference is approximately proportional to the axial displacement of the guide piston. This has the consequence that the ratio between contact pressure (pressure in the second pressure chamber) and torque depends not only on the ratio, but also on the volume flow and the back pressure of the hydraulic fluid flowing through the second pressure chamber 42 and the torque. The invention has for its object to provide a torque sensing device in which the above-described unfavorable dependencies of the detected torque of the rotational speed, the flow, the back pressure and other variables are avoided.

A first solution of the invention task is achieved with a torque sensing device for a conical-pulley, which torque sensing device includes a rigidly connected to a shaft of a conical disk pair ramp surface, another ramp surface which is rigidly connected to a shaft surrounding, relative to the shaft axially displaceable and rotatable Fühikolben which ramp surfaces are designed such that changes in a change in the effective between the sensing piston and the shaft torque, the axial position of the sensing piston by rolling arranged between the ramp surfaces balls on the ramp surfaces, and a rigidly connected to a travel disc guide surface at the radial Inside the balls abut, wherein the travel disc with the shaft rotatably and axially displaceably connected and with a dependent of the axial position of the sensing piston hydraulic pressure in the direction of a rigid mi t is the shaft connected fixed disc is urged and the guide surface is shaped such that the radial distance between the balls and the axis of the shaft on the axial distance between the distance disc and the fixed disc depends and wherein the guide surface is designed such that the points of contact each one Ball with the ramp surfaces, the point of contact of this ball with the guide surface and the center of this ball lie in a radially directed plane.

This ensures that the centrifugal force is completely absorbed by reaction forces and causes no unfavorable speed dependence of the contact pressure.

Another object of the invention is to provide a torque sensing device for a conical-pulley transmission which includes a torque sensing device rigidly connected to a shaft of a cone pulley pair ramp surface, a further ramp surface which is rigidly connected to a shaft engaging, relative to the shaft axially displaceable and rotatable sensing piston, which Ramp surfaces are formed such that the axial position of the sensing piston changes by rolling arranged between the ramp surfaces balls on the ramp surfaces with a change in the effective between the sensing piston and the shaft torque, and a rigidly connected to a travel disc guide surface, at its radial inner side the balls with their radially outer Abut area, wherein the travel disc with the shaft rotatably and axially slidably connected and is urged with a dependent of the axial position of the sensing piston hydraulic contact pressure towards a rigidly connected to the shaft fixed disk and the guide surface is shaped such that the radial distance between the balls and the axis of the shaft depends on the axial distance between the travel disc and the fixed disc, wherein the guide surface is designed such that the contact points are each a ball with the ramp surfaces and the point of contact of this ball with the guide surface in a plane that has a predetermined angle to the radial direction.

This ensures that the centrifugal force causes a predeterminable by the angle speed dependence of the contact pressure, which can be taken into account in the control of the transmission.

It is advantageous that the pitch of the ramp surfaces decreases with increasing distance from their lowest point such that the quotient of contact pressure and torque is substantially independent of the positions of the ramp surfaces and the guide surface relative to one another.

Thus, the negative effect of the radial displacement of the contact point with respect to the centers of the balls can be compensated. This is achieved in that the radial, axial and circumferential displacements are arranged at each predetermined position of the guide surface such that the ratio of torque and contact pressure or pressure in the second pressure chamber remains substantially constant.

The invention, which can be used for substantially all types of cone pulley with integrated torque sensor, will be explained below with reference to schematic drawings, for example, and with further details.

In the figures represent:

1 shows two sectional views, cut in the plane l-l of FIG. 4 with respect to the circumferential direction different relative positions of the ramp surfaces to each other,

2 shows three sectional views, cut in the plane H-II of FIG. 4, wherein the ball is relative to the guide surface with respect to the circumferential direction in different positions, Fig. 3 is a view similar to FIG. 1 with respect to FIG. 1 different shape of the ramp surface and

4 shows a cross section through a drive-side portion of a conical-pulley wrap-type transmission of a type known per se.

The geometry according to the invention described below can be used in a transmission according to FIG. 4.

Fig. 1 shows in the figure part a) a ball 40 between the ramp surfaces 32 and 38, which are formed in the circumferential direction repetitively on the support ring 30 and the sensing piston 36.

Fig. 1a) represents the drehmσmentfreien state in which the sensing piston 36 is maximally approximated to the support ring 30. In the position shown in FIG. 1b) formed on the sensing piston 36 ramp surface 38 in the circumferential direction (y) due to a torque introduced by the input gear 54 relative to the ramp surface 32 of the support ring 30 is shifted, so that the ball 40 on the ramp surfaces by a certain extent is rolled and increases the distance between the support ring 30 and the sensing piston 36. As seen, a line connecting the points of contact P ₁ and P ₂ and the center M of the ball makes an angle with the X direction (direction of the axis of the input shaft 10). So that a plane containing the contact points Bi, B ₂ , the center M of the ball and the point of contact of the ball with the guide surface 58, remains radially directed, the mold surface 58, seen in a section according to H-II of Fig. 4 has the 2, wherein only one half is shown starting from the location radially above the lowest point of the ramp surface 32 of the support ring 30 in the circumferential direction. As can be seen, the guide surface has in its middle region a plateau 60 against which the ball 40 rests in the position according to FIG. 2 a) at the point Pi.

Fig. 2b) shows the contact between the ball 40 and the guide surface 58 in the state of Fig. 1 b), wherein the contact points P ₂ , P ₃ emigrate laterally and a plane containing the points Bi, M, B ₂ , P _4th (Middle between P ₂ and P ₃ ), remains radially directed. In the position according to FIG. 2c), which corresponds to the pumping position, ie the greatest possible displacement between the ramp surfaces 32 and 38 in the circumferential direction, the contact point P5 has moved further away from the effective contact point P4 of FIG. 2c.

The guide surface 58 may be matched to the ramp surfaces 32 and 38 such that a plane containing the points of contact of the ball with the ramp surfaces and the guide surface as well as the ball center lies in the radial direction. This ensures that the force acting on the balls 40 with increasing speed centrifugal force is completely taken over by reaction forces and there is no unfavorable speed dependence of the contact pressure. The guide surface 58 may also be configured such that the points of contact of the ball with the ramp surfaces and with the guide surface define a plane having a predetermined angle with the radial direction. As a result, a prescribable speed dependence of the contact pressure is achieved, which can be taken into account in the hydraulic control of the conical disk wrap transmission.

Fig. 3 shows a comparison with the Fig. 1 modified form of the ramp surfaces, wherein only the ramp surface 32 of the support ring 30 is shown. As can be seen, the pitch α of the ramp surface 32 changes in the circumferential direction y, the pitch becoming smaller as the distance from the lowest point increases. With this decreasing slope in the circumferential direction of the negative influence of the radial displacement of the contact point with respect to the ball center M can be compensated by the radial, axial and circumferential displacements at each predetermined position of the ramp surface 32 or guide surface 58 change such that the quotient of r • tan (α), (corresponds to the torque) and the contact pressure or the pressure in the second pressure chamber 42 with a change of r and / or α remains substantially constant, r is the radial distance of the contact point B from the axis of the input shaft 10th and α = α (r) is the radial distance dependent main ramp angle, ie the slope of the ramp at the lowest position of the ball 40 shown in FIG. LIST OF REFERENCE NUMERALS

input shaft

movable disk

cylinder ring

Piston first pressure chamber

drilling

annulus

radial bore

axial bore

support ring

ramp surface

sensing piston

ramp surface

Ball second pressure chamber

supply

derivation

supply port

discharge port

poor

input gear

ring part

guide surface

plateau

Claims

claims

A torque sensing apparatus for a conical pulley, which includes torque sensing means, a ramp surface (32) rigidly connected to a shaft (10) of a cone pulley pair, a further ramp surface (38) rigid with a shaft which is axially displaceable relative to the shaft rotatable sensing piston (36) is connected, which ramp surfaces are formed such that changes in a change in the effective between the sensing piston and the shaft torque, the axial position of the sensing piston by rolling arranged between the ramp surfaces balls (40) on the ramp surfaces, and a rigidly connected to a travel disc (14) guide surface (58), against the radial inside of the balls, wherein the travel disc rotatably connected to the shaft and axially displaceable and with a dependent on the axial position of the sensing piston hydraulic pressure in the direction of a rigid associated with the while Hard disk is urged and the guide surface is shaped such that the radial distance between the balls and the axis of the shaft depends on the axial distance between the disk and the fixed disk, characterized in that the guide surface (58) is designed such that the points of contact each of a ball (40) with the ramp surfaces (32, 38), the point of contact of this ball with the guide surface (58) and the center of this ball lie in a radially directed plane.

2. Torque sensing device for a conical-pulley, which includes torque sensing device, a rigidly connected to a shaft (10) of a cone pulley pair ramp surface (32), a further ramp surface (38) rigidly with a shaft surrounding, relative to the shaft axially displaceable and rotatable sensing piston (36) is connected, which ramp surfaces are formed such that changes in a change in the effective between the sensing piston and the shaft torque, the axial position of the sensing piston by rolling arranged between the ramp surfaces balls (40) on the ramp surfaces, and a rigid with a travel disc (14) associated guide surface (58), against the radial inside of the balls, wherein the travel disc with the shaft rotatably and axially displaceably connected and with a dependent of the axial position of the sensing piston hydraulic contact pressure in the direction of a rigid the wave v and the forming surface is shaped such that the radial distance between the balls and the axis of the shaft depends on the axial distance between the travel disc and the fixed disc, characterized in that the guide surface (58) is designed such that the Contact points each of a ball (40) with the ramp surfaces (32, 38) and the point of contact of this ball with the guide surface (58) lie in a plane which has a predetermined angle to the radial direction.

3. A torque sensing device according to claim 1 or 2, characterized in that the slope of the ramp surfaces (32, 38) decreases with increasing distance from the lowest point thereof such that the quotient of contact pressure and torque substantially independent of the positions of the ramp surfaces and the guide surface (58) is relative to each other.