DE102011016007A1 - Reversible freewheel device for crankshaft belt pulley for transferring torque to perform e.g. starter generator operation in automobile, has inner ring including ramp contour along direction of freewheel cage, which includes contour - Google Patents

Abstract

The freewheel device (1) has an outer ring (3) rotating relative to an inner ring (2). A clamp body i.e. clamping roller (5), is arranged in a freewheel cage (4) between the inner and outer rings, and transfers rotational torque between the inner and outer rings. The inner ring includes a ramp contour (7) along direction of the freewheel cage, which includes a contour corresponding to the ramp contour such that switching of the freewheel cage is taken place during rotation of the cage. The cage rotates between two end positions.

Description

The invention relates to a switchable freewheel device, in particular for use in crankshaft pulleys, as used for starter generators, stationary air conditioning, pulse start and boost.

In the automotive industry, belt-driven starter generators are increasingly being used to reduce fuel consumption.

In belt-driven starter generators (RSG systems), the generator pulley transfers the torque to start the engine in the start cycle. Thus, in a possible implementation of an automatic start-stop system at the start of the internal combustion engine, the starter generator (ie an electric machine which functions as a generator during operation of the internal combustion engine and functions as a starter motor when starting the internal combustion engine) drives a pulley via a belt, which coaxially attached to the crankshaft of the internal combustion engine. The effective direction of the torque with respect to the normal operation of the combustion or drive motor, during which torques are transmitted in a direction of rotation (operating direction) of the crankshaft, reverses when the engine is restarted. This opposite direction of rotation of the crankshaft can be referred to as the starting direction. In addition to a pure start-stop function with such a system and additional functions such. B. boost and regenerative braking, feasible. At Boost, the torque of the drive motor is supported by the starter generator.

To carry out these functions or an improved quality of their execution, a great variety of solutions are known from the prior art.

So stands the in DE 103 59 632 A1 described drive transmission device before the use of a starter generator, the torque or power transmission in both directions with simultaneous decoupling option should be done. For this purpose, the shaft ring and the pulley are non-positively coupled via a centrifugal clutch, so that with active drive of the shaft ring via the starter generator with closed centrifugal clutch introduced into the shaft ring torque is transmitted to the pulley, wherein the centrifugal clutch opens when reaching a limit speed and decoupled the shaft ring from the pulley. This limit speed is reached when the engine is started and the pulley is driven by the engine. The pulley can now due to their freewheeling coupling with the shaft ring their normal function, namely to drive the generator shaft to the actual generator operation, while simultaneously possible via the freewheeling decoupling for damping irregularities. If the speed decreases again, which is usually the case when the engine is switched off, the centrifugal clutch closes when the limit speed falls below the limit. The shaft ring and pulley are coupled together again.

In DE 102 53 495 A1 discloses a generator freewheel for a belt-driven starter generator, which includes the combination of two oppositely acting freewheels. The integrated in a pulley freewheel device has two axially on a ring plane juxtaposed freewheels, an inner freewheel and an outer freewheel on. In this case, the freewheel associated with the starting operation is deactivated after reaching a limit speed corresponding to the normal operation, and the second freewheel comes into operation synchronously with it.

Also in DE 102 58 907 A1 described freewheel device which is integrated in a pulley of a starter generator comprises two coaxially arranged, axially spaced pulleys with separate storage and separate freewheels, which include mutually opposite directions of action.

In the DE 10 2008 011 479 A1 The disclosed starter of an internal combustion engine has an electric starter and a starter generator associated with a traction mechanism drive, wherein the electric starter is to be operated alone or together with the starter generator. By means of a start-stop device, an optimization of a cold start of the internal combustion engine with an electric starter should take place. In this case, the starter generator is energized in a controlled manner to start the internal combustion engine in synchronism with the actuation of the electric starter. As a result, a defined torque can be introduced into the traction drive via the starter generator, as a result of which the drive dynamics are improved and, in particular during a cold start, the starting phase can advantageously be significantly shortened. The structure of this known starting device further provides a starter generator with a built-in pulley freewheel over which the starter generator is connected to the traction mechanism.

The known solutions for actuating a switchable freewheel require a large installation space or an enlarged belt drive to maintain the required gear ratios with an enlarged crankshaft pulley. Alternatively, it would be necessary to dispense with certain functionalities to reduce the space requirement.

It is therefore an object of the invention to provide a switchable freewheel device, which is characterized in particular by a compact, space-neutral design and guaranteed by their switching a torque flow of the belt drive on the crankshaft, creating a boost function of an electric motor to support the Internal combustion engine is enabled.

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

The switchable freewheel device has an inner ring and a relatively rotatable outer ring, and between them arranged in a freewheel cage rollers which are suitable to transmit torque between the inner ring and outer ring, wherein the inner ring towards the freewheel cage a ramp contour and the freewheel cage a corresponding thereto Contour, such that upon rotation of the freewheel cage, the switching of the freewheel device takes place, the flow of torque from the belt drive (which communicates with the outer ring) on the crankshaft (which communicates with the inner ring), creating a boost function to support the Internal combustion engine is enabled. The fact that the switching of the freewheel is not centrifugally operated, but by means of rotation of the freewheel cage, a compact design of the freewheel assembly is ensured.

Preferably, the freewheel cage is rotatable between two end positions, wherein the rotation of the freewheel cage and the resulting switching of the freewheel device, advantageously electromotive, in particular by means of a stator and a rotor having electric motor (electric motor). The electromotive switching of the freewheel device ensures a particularly effective boost function.

The two end positions of the cage can be realized by stops between the cage and inner ring, which can be integrated into the ramp geometry.

An advantageous embodiment of the invention is that the rotor of the electric motor forms the freewheel cage or is connected thereto and that the stator of the motor is either rotationally coupled to the inner ring and rotates with this or is mounted on a stationary housing.

In this case, the rotor of the starter generator can be fixed against rotation via an additional element on the cage. The cage and the stator preferably have a common storage in the radial direction.

In particular, in an arrangement of the stator on a rotating housing, a position detection of the rotor should take place.

The electrical power supply is advantageously realized via the stationary housing to the rotor and the stator of the electric motor by means of rotational transmission in each case via a sliding contact or a roller bearing, wherein power supply lines to the stator and the rotor must be electrically insulated from each other. This is done by a transformer (as in shown), which consists of an electrically insulating material (eg., Plastic). The rotary feedthrough and the stator are mounted on this radially. Likewise, the stator is mounted rotationally and rotationally on this, whereby the torque flow is ensured by the stator via the transformer to the inner ring.

The torque, which is supported on the stator when it is coupled to the inner ring, is in turn advantageously supported via a rotation on the inner ring of the freewheel. The torque support is coupled simultaneously with the current supply to the coils of the stator.

By the freewheel device according to the invention, the torque and its course by the number of poles of the stator and the rotor and the distance of the poles to each other is adjustable.

A change in the direction of rotation of the freewheel cage takes place by reversing the polarity of the electric motor or in that the freewheel cage acted upon in a preferred direction with a force / moment and that to a spring force and / or a magnetically induced force acts on the freewheel cage, so that a change the direction of rotation of the cage without reversal can be achieved by the cage by means of the action of the spring force and / or the magnetically induced force remains in a preferred direction.

If the freewheel is to be switched, the stator is energized via the power supply lines whereby the freewheel cage is rotated.

Upon reaching the end position, which is determined by a stop, the torque of the freewheel is transmitted in the opposite direction. This is detected by the torque flow of the starter-generator. Thus, the energization of the stator for the freewheel switching is interrupted. If now the freewheel to be switched back to its original position, the rotation of the cage is realized by reversing the polarity of the power supply lines for the stature. The energization is finished as soon as the starter-generator has detected the changeover and consequently the torque flow.

The switching by means of an integrated electric motor can also be realized in such a way that the cage always has a preferred direction, for example by a spring or a permanent magnet. By energizing the stator, the cage is twisted. A fixation of the cage in the desired position is then possible only by permanent energization of the stator, as this against the preferred direction (realized by the spring or the permanent magnet) must hold the cage in position. As a result, a reverse polarity of the electric motor is not necessary, which can be dispensed with a 2-fold rotary feedthrough (1 ball bearings instead of 2 ball bearings).

In principle, there are two ways to arrange the air gap between the stator and the rotor. It is possible to provide a radial or an axial air gap between them. With the radial air gap, the rotor can rotate 360 °. At an axial air gap, the effect is comparable to a solenoid. As a result, no 360 ° rotation is possible because the rotor pole meets the stator pole and this results in positive locking. Advantage of this variant, however, is the slightly larger effective radius, which sets a larger torque. A disadvantage is the limited range of rotation of the cage due to the magnetic force.

The invention realizes a freewheel for RSG transmission applications in which the boost function of the electric motor in the gear ratio 1: 1 is desired. The switching of the freewheel, whereby the torque flow reverses, is realized by turning the freewheel cage, whereby the pinch rollers are moved to the opposite clamping track on the inner ring. This is possible by integrating an electric motor in which the rotor is part of the cage and the stator is fixed against rotation on the freewheel inner ring. The power transmission takes place by means of rotary transmission from the stationary housing to the rotating pulley, for example by ball bearings.

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

1 a cross section through a switchable freewheel device in a sectional plane perpendicular to the axis of rotation A,

2 a detail K after 1 .

3 a top view of a switchable freewheel device in the direction of the axis of rotation A,

4 a detail Y after 3 ,

5 a section through a switchable freewheel device along the line BB 3 .

6 Possibilities of arrangement of the air gap between stator and rotor.

A freewheel device according to the invention 1 is used, for example, the switching of a freewheel for RSG (belt-driven starter generator) applications in which the torque applied by the starter generator to the pulley RS torque is transmitted directly to the crankshaft W. This operating state is referred to as a 1: 1 boost and allows the support of the internal combustion engine by the torque of the starter generator. The application of the switchable freewheel device 1 In particular, crankshaft pulleys are intended for starter generator operation, stationary air conditioning, pulse starting and boosting.

In 1 are - as well as in the 2 . 3 . 4 and 5 - Only the invention essential components shown and described. So shows 1 a sectional view of the switchable freewheel device 1 in a sectional plane perpendicular to the axis of rotation A of a crankshaft W not shown in detail of an internal combustion engine. The freewheel device 1 is here in a, also not shown here, pulley RS integrated, which in turn via the freewheel device 1 can transmit a torque to the crankshaft W. The freewheel device 1 includes an inner ring 2 (which is star-shaped with the use of sprags in the form of rollers and is therefore often referred to as the inner star) and an outer ring 3 as well as a cage 4 in which clamping body in the form of pinch rollers 5 are arranged. The inner ring 2 is here by means of a mounting screw 6 attached to the crankshaft W. The pinch rollers 5 receiving cage 4 is designed as a rotatable slide bearing. The known spring-loaded pinch rollers 5 stand with a profiled, a ramp geometry 7 forming lateral surface of the inner ring 2 in active connection.

According to 2 is a detail after 1 in which an enlarged view of the ramp geometry 7 you can see. In this case, on the inner circumference of the sliding bearing or cage 4 cam 8th provided with the outer circumference of the inner ring 2 existing recesses 9 can be brought into engagement and serve as anti-rotation. The cage 4 is arranged rotatable between two end positions. These end positions are characterized by two stops, not shown here, between cage 4 and inner ring 2 are arranged realized.

In 3 is a plan view of the reversible freewheel device 1 shown pointing in the direction the axis of rotation A is looked. The switching or twisting of the cage 4 Electric motor by means of an electric motor. For this purpose is on the inner ring 2 the freewheel device 1 at least one coil 10 with a stator 11 arranged the electric motor. The stator 11 is twist-proof on the inner ring 2 fixed to the freewheel. The rotor 12 of the electric motor makes a cage 4 the freewheel or is part of the cage 4 , About the number of poles of the stator 11 and the rotor 12 can as well as over the distance of the poles to each other, the torque and the torque curve over a circumference of 360 ° - or in dependence on the angle of rotation of the cage 4 - be set.

According to 3 is the cage 4 for example, in a rotated by a twist angle α = 9 ° position. The electrical power is supplied by means of rotational transmission from the stationary housing (not shown) on the coils 10 of the stator 11 , which is rotatably connected to the inner ring (not labeled here). The rotary transmission is preferably via ball bearings 13.1 . 13.2 realized. The ball bearings 13.1 . 13.2 are as well as the stator 11 on a transmission element made of an electrically insulating material 14 radially mounted, wherein the stator 11 In addition, also rotationally arranged against rotation. Thus, the torque flow from the stator 11 over the transmission element 14 on the inner ring 2 guaranteed.

in 4 is an enlarged detail Y out 3 shown in the attached to the outer ring 3 radially inwardly adjacent components of the electric motor are shown enlarged. On the outer ring 3 are the pinch rollers 5 in the cage 4 be guided, as a rotor 12 is trained. Spaced with an air gap LS is radially inside the rotor 12 the stator 11 with coils 10 arranged. The switching of the electric motor is by reversing the polarity of the two power supply lines to stator 11 and rotor 12 realized. This allows the cage 4 be twisted in one direction and the other. The prerequisite for this is that the power supply lines are electrically insulated from one another. This is done by the transmission element 14 guaranteed.

5 shows a section through the freewheel device 1 along the BB line 3 , That's on the stator 11 supporting torque is in turn via the rotation on the inner ring 2 supported by the freewheel. The torque support is simultaneously with the power supply for the coil 10 coupled. The rotary feedthrough for the power supply to the stator 11 and rotor 12 is preferably over the ball bearings 13.1 . 13.2 realized because they have, for example, a slip ring solution almost no wear and have efficiency advantages.

A changeover of the electric motor, causing a change in the direction of rotation of the cage 4 is achieved takes place by reversing the polarity of the two current supply realizing power supply lines 15 , This is an electrical insulation of the two power supply lines 15 necessary to each other. This is done by the transmission element 14 ensured, which consists of an electrically insulating material (eg made of plastic).

If the freewheel is to be switched, the stator 11 via the power supply lines 15 energized, causing the rotor 12 rotates and thus designed as a rotor cage 4 we twist. After reaching one of the two end positions of the cage 4 the torque of the freewheel is transmitted in the opposite direction. This is detected by the torque flux of the starter generator. Thus, the energization of the stator 11 interrupted for the freewheel switchover. If now the freewheel should be switched back to its original position, by reversing the polarity of the power supply lines 15 for the stator 11 the corresponding twisting of the cage 4 realized. The energization is completed as soon as the starter generator has detected the changeover and, consequently, the torque flow.

The switching by means of an integrated electric motor can also be realized in accordance with an embodiment, not shown, in such a way that the cage 4 always has a preferred direction (for example, by the action of one or more springs spring and / or a permanent magnet). By energizing the stator, the cage is twisted. A fixation of the cage in the desired position is then possible only by permanent energization of the stator, as this against the preferred direction (by spring or magnet causes) must hold the cage in position. An advantage of this embodiment of the switchable freewheel device that polarity reversal of the electric motor is not necessary. As a result, the rotary feedthrough does not have to be double, but only simple, ie only one is needed instead of two ball bearings.

It is also possible according to a non-illustrated embodiment, the use of a stator fixed to the housing, which is not co-rotating. However, this requires a position detection of the rotor in order to energize the respective coil and thus to ensure the rotation of the cage.

In 6 are the schematic diagrams of the two ways of arranging an air gap LS between the stator 11 and rotor 12 represented by the electric motor. The whistle here show the direction of rotation of the rotor 12 at.

On the left side of the 6 is the principle of the electric motor listed, in which sets a radial air gap LS - the rotor 12 can twist 360 °.

On the right side, an axial air gap LS is set - comparable to a lifting magnet. Since in this case the rotor pole meets the stator pole, a positive connection occurs. A 360 ° rotation is not possible. An advantage of the latter variant is the slightly larger effective radius, which sets a larger torque. The disadvantage, however, is the limited range of rotation of the cage 4 due to the magnetic force. The Ka 4 and the stator 11 should be stored together as possible, so as to the air gap LS between the stator 11 and rotor 12 to keep small.

In addition to the features described above, the freewheel device is characterized 1 also characterized in that an attenuation of the crankshaft vibrations in generator mode by means of freewheeling, wherein the freewheel is not executed centrifugal force. In summary, it should be noted that the freewheel on the opposite ramp geometry 7 is switchable, whereby a torque transmission takes place in the opposite direction. Switching takes place via a rotation of the cage 4 , causing the pinch rollers 5 on the opposite clamping track on the inner ring 2 to be moved. Here is the cage 4 rotatory defined by two end positions. The anti-twist protection of the cage 4 is due to a form / frictional engagement between the cage 4 and inner ring 2 realized. The the rotor 11 of the electric motor / starter generator cage 4 can also have an additional element with the cage 4 be fixed against rotation. The number of poles of the stator 11 and the rotor 12 should be selected according to the torque. Similarly, the distance of the poles on the stator 11 to be provided so that within the twisting range of the cage 4 a constant torque curve in the circumferential direction can be realized. The rotor 12 is against the inner ring 2 and electrically isolating the power supply from the environment. The rotary transmission for the power supply takes place here by means of a low wear ball bearing 13.1 . 13.2 ,

Good efficiency also has the arrangement of the rotary feedthrough on a small diameter.

Are two rotational transmissions provided for the polarity reversal of the electric motor / starter generator, they are electrically insulated from each other. For a high torque are stature 11 and rotor 12 on a large diameter (according to the installation space) to choose.

The switchable freewheel device according to the invention 1 is thus possible by the integration of the electric motor, wherein the rotor 12 Part of the cage 4 is or is rotationally coupled and the stator 11 against rotation on the inner ring 2 is fixed. The power transmission takes place by means of rotary transmission from the stationary housing to the rotating pulley. The freewheel device according to the invention 1 represents a compact unit that allows both the stationary air conditioning operation as well as the boost operation by the starter generator. The switching of the freewheel allows a flow of torque from the belt drive to the crankshaft, whereby the boost function of the generator comes into operation to support the internal combustion engine.

LIST OF REFERENCE NUMBERS

1

Freewheel device

2

inner ring

3

outer ring

4

Cage

5

clamping rollers

6

Mounting screw

7

Ramp geometry / ramp contour

8th

cam

9

recesses

10

Kitchen sink

11

stator

12

rotor

13.1

ball-bearing

13.2

ball-bearing

14

transmission element

15

power supply

A

axis of rotation

LS

air gap

RS

pulley

W

crankshaft

α

angle of twist

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 10359632 A1 [0005]
• DE 10253495 A1 [0006]
• DE 10258907 A1 [0007]
• DE 102008011479 A1 [0008]

Claims (10)

Reversible freewheel device ( 1 ), with an inner ring ( 2 ) and a relatively rotatable outer ring ( 3 ) and in between in a freewheel cage ( 4 ) arranged clamping bodies in the form of clamping rollers ( 5 ), which torque between inner ring ( 2 ) and outer ring ( 3 ), wherein the inner ring ( 2 ) towards the freewheel cage ( 4 ) a ramp contour ( 7 ) and the freewheel cage ( 4 ) have a corresponding contour, such that upon rotation of the freewheel cage ( 4 ) the switching of the freewheel device ( 1 ) he follows. Reversible freewheel device ( 1 ) according to claim 1, characterized in that the freewheel cage ( 4 ) is rotatable between two end positions. Reversible freewheel device ( 1 ) according to claim 1 or 2, characterized in that the rotation of the freewheel cage ( 4 ) and the resulting switching of the freewheel device ( 1 ) by means of a stator ( 11 ) and a rotor ( 12 ) having electric motor (electric motor) takes place. Reversible freewheel device ( 1 ) according to one of claims 1 to 3, characterized in that the rotor ( 12 ) of the electric motor, the freewheel cage ( 4 ) or is connected to it and that the stator ( 11 ) of the motor either against rotation with the inner ring ( 2 ) is coupled and rotates with this or stored on a stationary housing. Reversible freewheel device ( 1 ) according to one of claims 1 to 4, characterized in that it comprises means for detecting the position of the rotor ( 12 ) having. Reversible freewheel device ( 1 ) according to one of claims 1 to 5, characterized in that the electrical power supply via the stationary housing to the rotor ( 12 ) and to the stator ( 11 ) of the electric motor. Reversible freewheel device ( 1 ) according to claim 6, characterized in that the electrical power supply is realized by means of rotary transmission in each case via a sliding contact or a rolling bearing. Reversible freewheel device ( 1 ) according to one of claims 1 to 7, characterized in that the power supply lines ( 15 ) to the stator ( 11 ) and the rotor ( 12 ) of the electric motor are electrically insulated from each other. Reversible freewheel device ( 1 ) according to one of claims 1 to 8, characterized in that the torque and its course by the number of poles of the stator ( 11 ) and the rotor ( 12 ) and the distance between the poles is adjustable to each other. Reversible freewheel device ( 1 ) according to one of claims 1 to 9, characterized in that - either a change in the direction of rotation of the freewheel cage ( 4 ) is achieved by reversing the polarity of the electric motor or - that the freewheel cage ( 4 ) can be acted upon in a preferred direction with a force / moment and in that a spring force and / or a magnetically induced force on the freewheel cage ( 4 ) works, so. that a change in the direction of rotation of the cage ( 4 ) can be achieved without reversing the polarity by 4 ) remains in a preferred direction by means of the action of the spring force and / or the magnetically induced force.

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