WO2003036114A2

WO2003036114A2 - Pulley

Info

Publication number: WO2003036114A2
Application number: PCT/EP2002/011438
Authority: WO
Inventors: Uwe Michael; Peter Kattwinkel
Original assignee: Ina-Schaeffler Kg
Priority date: 2001-10-19
Filing date: 2002-10-12
Publication date: 2003-05-01
Also published as: DE10151795A1; AU2002349349A1; WO2003036114A3

Abstract

The invention relates to a pulley fitted with a hub (2) and a tread lining (1). A free engine clutch is arranged between the hub (2) and the tread lining (1). A slip clutch is also arranged between the hub (2) and the tread lining (1), said slip clutch connecting the hub (2) and the tread lining (1) in a frictionally engaging manner below a limit torque and disengaging the hub (2) from the tread lining (1) above the limit torque in the free running direction of the free engine clutch.

Description

pulley

The present invention relates to pulleys. In the unit drive of modern internal combustion engines, pulleys are often arranged on the drive shaft of the alternator, and a one-way clutch is arranged between the hub and the barrel casing. The invention relates in particular to the latter pulleys.

From DE 195 11 188 C2, for example, a device for damping torsional vibrations in a drive train has become known. A pulley is arranged on a drive shaft of an alternator, with a roller-mounted one-way clutch being arranged between the barrel jacket and the hub. The one-way clutch takes on the task of decoupling the phase of the deceleration of the rotational irregularities of the crankshaft from the rotationally inert drive shaft. The rotational irregularities are due to the combustion process of the piston internal combustion engine.

It has also been proposed to decouple the crankshaft pulley, for example by means of a rubber element arranged between the crankshaft and the pulley. With this arrangement, the rotational irregularities of the crankshaft are more or less decoupled from all the auxiliary units arranged in the belt drive. However, problems arise when starting the engine because a resonance point has to be run through. Because the decoupled crankshaft pulley forms an oscillatory system with the ancillary units arranged in the belt drive. For this reason, a so-called start-stop squeak can occur due to slippage between the alternator pulley and the belt. The slip occurs when a moment engaging the alternator shaft is reached that is higher than a limit torque. The limit torque corresponds to the torque that can be transferred from the belt to the pulley.

However, the combination of the arrangement of the freewheel between the pulley and the alternator shaft with the decoupled crankshaft pulley mentioned above creates a new problem: the start-stop squeak has been eliminated. However, the resonance speed increases approximately to the engine idling speed. This causes impermissibly high oscillation angles of the crankshaft pulley in relation to the crankshaft. This increases wear at the coupling point between the crankshaft and crankshaft pulley.

The object of the present invention is to provide an improved pulley in which these disadvantages are eliminated.

According to the invention this object is achieved by the pulley according to claim 1. Below the limit torque, the slip clutch provided according to the invention frictionally connects the hub to the barrel jacket, because this is just set to this limit torque. The limit torque is undershot when the engine is idling or at a higher speed. So here is a situation where the alternator pulley is rigidly connected to the alternator shaft. The crankshaft pulley can therefore be decoupled without the problem mentioned at the outset, according to which excessive oscillation angles occur on the decoupled crankshaft pulley.

When starting the engine, torques may be greater than the limit torque. In this situation, there can be no slippage between the belt and the alternator pulley, because the slip clutch according to the invention enables the pulley to slip through against the alternator shaft. The start-stop squeak has been eliminated. For the entire speed range that occurs in practice, it is consequently ensured that, on the one hand, the start-stop squeak is eliminated and, on the other hand, that no unacceptable oscillation angles occur on the crankshaft pulley, especially at idling speed. The slip clutch is set so that the idler pulley is rigidly coupled to the alternator shaft at idle speed or higher speeds in the deceleration phase of the rotational irregularity of the crankshaft. In this situation, the freewheel becomes ineffective or at least approximately ineffective.

Clamping body freewheels and wrap spring freewheels, but also clamping roller freewheels, for example, can be used as the one-way clutch.

A further development according to the invention provides that the barrel casing is mounted radially opposite the hub via sliding bodies, a solid friction being set between the sliding bodies on the one hand and the hub and / or the barrel casing on the other hand. The sliding bodies provided according to the invention therefore perform two functions: firstly, they ensure a perfect radial bearing, so that the function of, for example, a clamping roller freewheel is also ensured. Secondly, they take on the function of a slip clutch that slips above a set limit torque and that transfers a torque below the limit torque perfectly between the barrel jacket and the hub.

In a known manner, a thrust washer can be arranged on the end face between the hub and the running jacket. However, a further development according to the invention provides that a friction body for solid-body friction is provided between the thrust washer on the one hand and the running jacket and / or the hub on the other hand. To apply the solid friction, a tensioned spring can be provided, which clamps the friction body between the disc on the one hand and the barrel jacket and / or the hub on the other.

If a one-way clutch with clamping bodies is provided, which are spring-loaded against clamping tracks, one clamping track being assigned to the running jacket and the other clamping track to the hub, a special development according to the invention provides that the clamping body is formed by a wedge body, one of which has a friction surface against the a clamping track, which is also designed as a friction surface, is pressed on, the friction surfaces slipping above the limit torque in the freewheeling direction. In this case, the clutch provided here takes on two functions: on the one hand, a defined friction torque is set in the freewheeling direction, so that slipping is only possible when a limit torque is exceeded. Secondly, it is ensured in the opposite blocking direction of the freewheel that a rotation between the barrel jacket and the hub is not possible due to a non-positive connection due to the freewheel.

Another slip clutch according to the invention can comprise a lever which springs against each other, one of which is assigned to the hub and the other of which is associated with the barrel jacket. A friction ring can also be arranged between the lever and the friction surface assigned to the barrel jacket or the hub, which friction ring is pressed against the friction surface of the hub or the barrel jacket under the force of the lever acted upon.

The invention is explained in more detail below with reference to five exemplary embodiments shown in a total of seven figures. Show it:

1 shows a pulley according to the invention in longitudinal section,

FIG. 2 shows an equivalent circuit diagram for the pulley according to the invention from FIG. 1, FIG. 3 shows a further pulley according to the invention in longitudinal section,

FIG. 4 shows a modified slip and one-way clutch provided according to the invention,

Figure 5 shows another modified slip and

Overrunning clutch

FIG. 6 shows an equivalent circuit diagram for the slip and overrunning clutch from FIG. 5,

Figure 7 shows another slip and one-way clutch.

The pulley according to the invention from FIG. 1 has a running jacket 1, a hub 2 and a roller-bearing freewheel arranged between the hub 2 and the running jacket 1, which is formed from a pinch roller freewheel 3 and radial roller bearings 4 arranged on both end faces of the pinch roller freewheel 3. The freewheel forms a so-called freewheel unit, in which the clamping roller freewheel 3 and the radial roller bearings 4 are arranged between an inner and an outer sleeve 5, 6. The figure shows that the belt pulley is screwed onto a drive shaft 7 of an auxiliary unit, not shown.

A thrust washer 8 is attached to the face of the barrel jacket 1. Between a cover 9 on the end face and the thrust washer 8, a friction disk 10 is provided, which is received on the hub 2 in a rotationally fixed manner. In the illustration, the friction disk 10 is clamped elastically between the cover 9 and the thrust washer 8. A relative rotation between the friction disk 10 and the running jacket 1 or the thrust washer 10 is only possible above a limit torque. If, for example, the pulley according to the invention is used in the unit drive of an internal combustion engine is, namely on the generator shaft, this limit torque can be exceeded if the moment of inertia of the rotating generator shaft is correspondingly large with a strong deceleration of the crankshaft. Unwanted squeaking noises, especially when starting or stopping the engine, can be avoided by the defined torque limit.

FIG. 2 shows an equivalent circuit diagram of the friction disk according to the invention from FIG. 1, the position number 11 denoting a slip clutch and the position number 12 denoting a one-way clutch connected in parallel with the slip clutch 11.

The friction disk according to the invention according to FIG. 3 differs from that from FIG. 1 essentially in that instead of the radial roller bearings described above, sliding bodies 13 are provided which are in constant frictional contact with the inner sleeve 5 and / or the outer sleeve 6, wherein the outer sleeve 6 is arranged in a rotationally fixed manner with the barrel jacket 1 and the inner sleeve 5 in a rotationally fixed manner with the hub 2. Below the limit torque, there is therefore no relative rotation between the barrel jacket 1 and the hub 2, whereas if the limit torque is exceeded, slipping in the free running direction of the pinch roller freewheel 3 is possible. The sliders 13 are therefore part of the slip clutch and part of the one-way clutch.

In this pulley according to the invention, a friction disk, as described above, can be omitted.

Instead of the clamping roller freewheel, clamping bodies 14 can also be provided according to FIG. 4, which are sprung against clamping tracks 15, 16 by means of a spring 17. The clamping track 15 assigned to the barrel jacket 1, not shown, is cylindrical. The clamping track 16 assigned to the hub 2, not shown, is in the form of several over the circumference distributed clamping ramps 18 formed. The clamping ramps 18 together with the cylindrical clamping path 15 delimit wedge-shaped clamping gaps 19. The clamping bodies 14 also have a wedge shape. When the barrel jacket 1 is rotated clockwise, the wedge-shaped clamping body 14 is pulled into the clamping gap 19 by the spring force of the spring 17 and the frictional force between the barrel jacket 1 and the clamping body 14 and the freewheel is blocked. When rotating in the opposite direction, the friction force, which is transmitted from the running jacket to the wedge-shaped clamping body 14, presses it downward along the clamping ramp 18, so that no blocking can take place. The spring 17 ensures a defined contact pressure between the wedge-shaped clamping body 14 and the cylindrical clamping track 15, as a result of which a defined frictional torque is generated in this direction of rotation. The contacting surfaces of the wedge-shaped clamping body 14 and the cylindrical clamping path 15 are in frictional contact much larger than with a clamping roller, whereby the wear on the clamping body 14 due to the high friction torque is counteracted. In one sense of rotation, the clutch shown in FIG. 4 accordingly works as a slip clutch and in the opposite sense of rotation as a one-way clutch.

A modified clutch, which works in one direction of rotation as a one-way clutch and in the opposite direction as a slip clutch, is also shown in FIG. 5. Here, a ring 20 is arranged on the end face between the barrel jacket 1 and the hub 2. The ring 20 has a plurality of levers 21 which are distributed over the circumference and bent out of the ring plane. The free lever ends are seated in grooves 22 of a friction ring 23, which is pressed with its friction surface 24 against a friction surface 25 of the barrel casing 1 by the force of the pretensioned lever 21. When the barrel casing 1 is rotated from left to right in the illustration, the friction ring 23 is taken along a little to the right under the effective frictional force between the barrel casing 1 and the friction ring 23, the lever arms 21 tending to decrease the effective friction force. In this direction, the clutch shown here works as a slip clutch. In the opposite direction of rotation, the friction ring 23 rotated a little from the right to the left under the effective frictional force, the lever arms 21 rising further and pressing the friction ring 23 increasingly against the barrel casing 1, so that a frictional connection is established. The clutch shown here therefore works in this sense of rotation as a one-way clutch in blocking operation.

FIG. 6 shows, as a replacement diagram, a pulley with a clutch according to FIG. 5, a combined slip and overrunning clutch according to FIG. 5 being designated by item number 24.

The clutch shown in FIG. 7 also works according to the lever principle, but instead of a ring as in FIG. 5, a plurality of levers 25 which are arranged distributed over the circumference are provided, which have one end in troughs 26 of the hub 2 and with their opposite ends in the Troughs 22 of the friction ring 23 are arranged. Furthermore, a spring 27 is provided, which springs the lever 25 in one direction, so that this lever 25 stands up and presses the friction ring 23 with its friction surface 24 against the friction surface 25 of the barrel casing 1. The mode of operation of this clutch corresponds to the clutch according to FIG. 5.

reference numerals

Counterweight

hub

Clamping roller freewheel

Radial roller bearing inner sleeve outer sleeve

drive shaft

thrust washer

cover

friction

slip clutch

Overrunning clutch

sliding

clamping bodies

clamping track

feather

clamping ramp

nip

ring

lever

groove

friction ring

Slip and freewheel clutch

lever

trough

feather

Claims

claims

1. Pulley, with a hub (2) and with a barrel jacket (1), and with one between the hub (2) and the barrel jacket (1) effectively arranged

Freewheel clutch, characterized in that a slip clutch (10, 11, 21, 23) is effectively arranged between the hub (2) and the barrel jacket (1), which frictionally connects the hub (2) and the barrel jacket (1) below a limit torque , and above the limit torque the hub (2) of the barrel jacket (1) in the freewheeling direction

Freewheel clutch (3, 12, 14, 21, 23, 24, 25) decoupled.

2. Pulley according to claim 1, in which the barrel casing (1) is mounted radially with respect to the hub (2) via sliding bodies (13), wherein between the sliding bodies (13) on the one hand and the hub (2) and / or the barrel casing (1 ) on the other hand a solid friction is set.

3. Pulley according to claim 1, in which a thrust washer (8) is arranged on the end face between the hub (2) and the running jacket (1), wherein between the thrust washer (8) on the one hand and the running jacket (1) and / or Hub (2) on the other hand a friction body (10, 23) is provided for solid friction.

4. Pulley according to claim 3, wherein a tensioned spring (21, 27, 17, 9) the friction body (10, 23, 14) between the thrust washer (8) on the one hand and the barrel jacket (1) and / or the hub (2nd ) on the other hand.

5. Pulley according to claim 1, wherein the one-way clutch comprises clamping bodies (14) which are spring-loaded against clamping tracks (16, 18, 15), one clamping track (15) the running jacket (1) and the other clamping track (16 , 18) is assigned to the hub (2).

6. Pulley according to claim 5, wherein the clamping body is formed by a wedge body (14), one friction surface of which is pressed against the one designed as a friction surface clamping path (15), the friction surfaces slipping above the limit torque.

7. Pulley according to claim 1, wherein a lever (21, 25) springs against each other, one of which is associated with the hub (2) and the other of which is associated with the barrel jacket (1).