WO2012142991A1

WO2012142991A1 - Free wheel for a permanently engaged starter of a motor vehicle

Info

Publication number: WO2012142991A1
Application number: PCT/DE2012/000336
Authority: WO
Inventors: Michael Metz
Original assignee: Schaeffler Technologies AG & Co. KG
Priority date: 2011-04-20
Filing date: 2012-03-30
Publication date: 2012-10-26
Also published as: DE102012205270A1; DE112012001768A5

Abstract

The invention relates to a free wheel for a permanently engaged starter of a motor vehicle, provided with an outer ring for inducing a starting torque of the starter, an inner ring for transferring the starting torque to a drive shaft, especially a crankshaft, of an internal combustion engine, clamping bodies that are arranged between the outer ring and the inner ring and can be tilted in the peripheral direction, and a spring element coming into contact with a clamping body in order to provide a radially outwardly oriented pressure force on the clamping body against the outer ring, the outer ring having a radially inwardly projecting guiding shoulder for tilting the clamping body. In this way, power losses generated in an internal combustion engine of a motor vehicle can be reduced.

Description

Freewheel for a permanently einqespurten starter of a motor vehicle

The invention relates to a freewheel for a permanently starred starter of a motor vehicle, with the aid of the starter for starting an internal combustion engine of the motor vehicle with a drive shaft, in particular crankshaft, the internal combustion engine can be coupled, wherein the starter after the start of the internal combustion engine by the freewheel the internal combustion engine in Essentially does not slow down.

From DE 10 2009 008 599 A1, a freewheel for a permanently interlocked starter of a motor vehicle is known, which is arranged in the power flow direction between a starter ring of the starter and a crankshaft of an internal combustion engine. The freewheel has arranged between an inner ring and an outer ring tiltable clamping body, wherein the clamping body having a radially outwardly open groove for receiving a worm spring. The worm spring pulls the clamp body on the inner ring to frictionally connect the clamp body with the inner ring until acting on the clamp body centrifugal force is sufficient to overcome the radially inwardly acting spring force of the worm spring, whereby the freewheeling function of the freewheel is activated.

There is a constant need to reduce power losses occurring in an internal combustion engine of a motor vehicle.

It is the object of the invention to provide measures by means of which power losses occurring in an internal combustion engine of a motor vehicle can be reduced.

The object is achieved by a freewheel for a permanently starter starter of a motor vehicle with the features of claim 1. Preferred embodiments of the invention are set forth in the dependent claims.

According to the invention, a freewheel for a permanently interlocked starter of a motor vehicle, provided with an outer ring for initiating a starting torque of the starter, an inner ring for discharging the starting torque to a drive shaft, in particular crankshaft, an internal combustion engine, arranged between the outer ring and the inner ring in the circumferential direction tiltable sprags and one acting on the clamp body

| Confirmation copy | Spring element for providing a radially outwardly directed pressure force on the clamping body against the outer ring, wherein the outer ring has a radially inwardly projecting guide lug for tilting the clamping body.

With the help of the guide approach, a tilting of the clamping body can be at least supported by not only a frictional force of the outer ring but also about the guide approach required falsis a positive connection is provided for clamping the clamping body. Due to the possibility of positive locking between the clamping bodies and the guide projection, a lower tolerance sensitivity is given and the design of the free movement with respect to spring forces and force introduction points on the clamping body is simplified. The clamping body can be jammed by a particularly high security by tilting. For this purpose, the clamping body in particular in addition to a movable relative to the outer ring stop, for example, a arranged between the inner ring and outer ring detectable cage strike. Characterized in that the frictional clamping of the clamping body can be done by means of the guide lug, it is possible by the spring element to press the clamping body in a freewheeling position, so that the force acting on the clamping body centrifugal force and the radially outwardly directed spring force of the spring element cooperate and not against each other work. This allows a freewheeling function of the freewheel even at relatively low speeds, when the force acting on the clamping body centrifugal force is still relatively low. The net mass of the clamping body can be selected correspondingly low, resulting in a compact, space-saving and cost-effective design for the freewheel. A period in which the clamping body can grind on the inner ring and / or on the outer ring is thereby reduced, so that less frictional losses can occur in the freewheel. As a result, power losses occurring with the aid of the freewheel in an internal combustion engine of a motor vehicle can be reduced. In particular, in the case of the permanently starter starter, the outer ring of the freewheel is usually connected to a starter ring and therefore has the speed 0 when driving, that is, in the freewheeling operation of the freewheel. In a radially inwardly acting spring force on the clamping body, the clamping body would be decelerated by the outer ring again, as soon as the clamp body completely lift off the inner ring, so that the force acting on the clamping body centrifugal force would decrease. This would cause the clamp body would be pushed back against the inner ring by the spring force acting radially inward and would never completely lift off the inner ring while driving, which would constantly loss of power produced. By inverting the Freiiaufkonzept with a force acting radially outward on the clamp body spring force this power loss is avoided. The outer ring may in particular be directly or indirectly connected to a starting ring, which may be in permanent engagement with a drive pinion of the starter. Preferably, the outer ring is made in one piece with the starter ring. The inner ring may for example be designed as connected to the drive shaft of the internal combustion engine sleeve. Preferably, the inner ring is formed by the drive shaft itself, so that the inner ring can be configured integrally with the drive shaft. It is also possible that the inner ring is designed as a solid shaft, wherein a radially outwardly facing annular friction surface forms the inner ring for the clamping body. Particularly preferably, the clamping body are arranged within a wet space of the internal combustion engine, so that the clamping body can be lubricated for example with otoröl the internal combustion engine. A required sealing can be done, for example, by means of an attacking on a component of the freewheel shaft ndichtrings. The spring element provides a radially outwardly directed spring force on the clamping body. In particular, the clamping body are pressed by the spring force of the spring element in a freewheeling position in which a Momen- ten flow between the inner ring and the outer ring is interrupted via the clamping body.

In particular, the guide lug has a guide surface facing the clamp body, wherein the clamp body is slidable along the guide surface for clamping the outer ring with the inner ring. The contouring of the guide surface may correspond to the rolling movement of the clamp body during tilting. The guide surface can impose a force in one direction upon abutment of the guide projection on the clamping body, which supports a tilting of the clamping body. Since the clamping body is not only displaced but also tilted with the aid of the guide projection, the clamping body can be tilted particularly quickly in order to clamp the inner ring to the outer ring. A longer grinding of the clamp body is avoided.

Preferably, the clamping body is arranged between two guide lugs, wherein the guide lugs each have mutually facing guide surfaces on which the clamping body for a clamping of the outer ring with the inner ring on the guide surfaces along slidably. The clamping body can thereby be guided in both circumferential directions of the guide lugs. The guide lugs can thereby support both a jamming of the clamping body as well as a release of the clamp body tilting of the respective clamp body. Particularly preferably, a spring force in the direction of the guide lug is applied to the clamp body. The clamping body can thereby rest against the guide projection, in particular on the guide surface. The clamp body can thereby be tilted very fast to jam the inner ring with the outer ring and lock the freewheel. Slipping of the clamping body on a radially inwardly facing substantially cylindrical inner surface of the outer ring is thereby reduced. Friction losses can be reduced.

In particular, the spring force is applied in the direction of the guide approach to the spring element for providing the radially outwardly directed pressure force on the clamping body. The spring force radially outward and in the circumferential direction on the guide lug can thereby be applied by the same spring element. For this purpose, the spring element is designed, for example, as a wire bending spring which has a plurality of legs arranged at an angle in order to be able to provide the spring forces pointing in different directions. Various spring elements, which must be arranged collision-free for a specific sprag on a small space, can be avoided.

Preferably, the spring element exerts a spring force on at least two clamping bodies, preferably on all clamping bodies. The spring element can be designed, for example, annularly shot in order to be able to impress a spring force on all clamping bodies. For example, the spring element can be compressed in the radial direction to mount the spring element, wherein the spring element after assembly can act with a spring force radially outward on the clamp body.

Particularly preferably, a separate spring element is provided for each clamping body, wherein in particular the spring element is hooked in a holding ring provided in the outer ring. The clamping body can be easily mounted individually in each case in particular together with the associated spring element. In particular, it is possible for the spring element to choose a shape design in which the spring element acts on different sides of the clamp body. The clamping body may for example be inserted into the spring element, in particular be captively hooked, and mounted together with the spring element. For this purpose, in particular, the spring element can be easily hooked into the holding opening with a bent hook legs. In particular, the spring element rests on at least one clamping body and / or on at least one guiding lug on one axial side, preferably on both axial sides. The movement of the clamp body in the axial direction may be limited by the spring element. The clamping body can thereby be guided in the circumferential direction of the spring element, so that the clamping body in particular can only perform a tilting movement in the circumferential direction. In particular, when the spring element abuts axially on the clamping body and on the guide lug, the clamping body can be aligned in the axial direction of the spring element relative to the guide lug.

Preferably, a cage movable relative to the outer ring is provided for tilting the Kiemmkör- per. The cage has in particular in the axial direction between two clamping bodies extending fingers, which can strike at a relative movement of the cage to the respective clamping body in the circumferential direction of the clamping body to tilt the respective associated clamping body. At a start of the engine by means of the starter, the cage can tilt the clamp body in a clamping position in which the clamp body clamp the outer ring to the inner ring and thereby forcibly coupling the movement of the outer ring with the movement of the inner ring. The starter torque of the starter can then flow via the outer ring and the clamping body to the inner ring, so that the starter torque can be introduced into the drive shaft of the internal combustion engine to start the internal combustion engine. This tilting can be supported by the guide lugs, wherein it is also possible to provide the guide lugs only as a safety measure, if the friction between the outer ring and the clamping bodies for tilting should not be sufficient.

In particular, a frictional force is impressed on the cage with the aid of a pressure spring, in particular plate spring, wherein the pressure spring is supported in particular on a stationary component, preferably an engine block of the internal combustion engine. By the pressure spring, a sufficient frictional torque for the cage can be provided so that the cage can be moved relative to the clamping bodies and with a sufficiently large frictional torque can tilt the clamping body in the clamping position. During the freewheeling function of the freewheel, when the starter ring is not driven by the starter, in particular unnecessary relative movements of the pressure spring are avoided, so that substantially no frictional losses occur during the freewheeling function of the freewheel by the pressure spring. Preferably, the inner ring radially outward has a roundness tolerance of IT 7 to IT 10, in particular IT 8 to IT 9. The roundness tolerance is measured according to DIN ISO 286-1: 1990. By compared to the otherwise usual roundness tolerance of IT 6 to IT 7 lower circularity requirements on the inner ring, the production costs can be reduced. In particular, radially outwardly projecting unevennesses can apply a force directed radially outward onto the clamping bodies when, in order to achieve the freewheeling position of the clamping bodies, the inner ring performs a relative movement in the circumferential direction relative to the clamping bodies. Due to the lower contact surfaces, the lower roundness tolerance even leads to lower friction losses.

The invention further relates to a starter arrangement for starting an internal combustion engine of a motor vehicle, with a coupled via a freewheel on the internal combustion engine starter, wherein in particular the inner ring of the freewheel is formed by a drive shaft of the internal combustion engine and / or the outer ring by a starter ring of the starter. The freewheel can be trained and developed as described above. As a result, power losses occurring with the aid of the freewheel in an internal combustion engine of a motor vehicle can be reduced.

In particular, the outer ring is mounted on a drive shaft of the internal combustion engine. This leads to a comparatively small radial offset between the axis of rotation of the drive shaft of the internal combustion engine and the outer ring, so that the clamping body only have to compensate for a small radial offset. This allows lower manufacturing tolerances without affecting the function of the freewheel.

The invention will now be described by way of example with reference to the accompanying drawings with reference to preferred embodiments, wherein the features shown below, both individually and in combination may represent an aspect of the invention. Show it:

1 is a schematic perspective sectional view of a starter assembly,

2 is a schematic side view of a first embodiment of a freewheel for the starter assembly of Fig. 1, FIG. 3 shows a schematic side view of a second embodiment of a freewheel for the starter arrangement from FIGS. 1 and

4 shows a schematic perspective view of a spring element for the freewheel. 'Fig. 3.

The starter assembly 10 shown in Fig. 1 has a designed as a crankshaft drive shaft 12 and an engine block 14 of an internal combustion engine. To start the internal combustion engine, a starter, not shown, can be coupled via a freewheel 6 with the drive shaft 12. For this purpose, the starter can be permanently meshed in a starter ring 18, which is connected via a sprocket carrier 20 with an outer ring 22 of the freewheel 16. The sprocket carrier 20 is supported via a bearing 24 on a bearing seat 28 connected to the engine block 14 via a sealing ring 26. The bearing 24 can be sealed by an outer shaft seal 30 arranged between the sprocket carrier 20 and the bearing seat 28. Further, between the sprocket carrier 20 and the drive shaft 12, an inner shaft seal 32 is provided to seal the freewheel 16 against the drive shaft 12. In the illustrated embodiment, an inner ring 34 of the freewheel 16 is formed by the drive shaft 12 itself.

As shown in Fig. 2, the freewheel 16 between the outer ring 22 and the inner ring 34 clamping body 36 which can be tilted by means of a cage 38. For this purpose, the cage 38 between two clamping bodies 36 in the axial direction, that is substantially parallel to a rotational axis of the freewheel 16, extending fingers 40. Between the engine block 14 and the cage 38 designed as a plate spring pressure spring 42 is provided which exerts a sufficient frictional torque on the cage 38, so that the cage 38 with his fingers 40, the clamping body 36 can tilt without slipping before reaching the clamping state. In the illustrated embodiment, all clamping body 36 are pressed by means of a common spring element 44 radially outward. The spring element 44 is designed for this purpose as a complex bent wire bending spring. At the same time, the spring element 44 can press the respective clamping body 36 in the circumferential direction onto a guide surface 46 of a guide projection 48 protruding radially inward from the outer ring 22. This makes it possible, with the aid of the guide projection 48, to tilt the clamping body 36 in a form-fitting manner, if necessary, in order to clamp the inner ring 34 with the outer ring 22. The guide projection 48 furthermore has a circumferential direction away from the guide surface 46. Send back 50, which may optionally also be configured as a further guide surface for tilting the clamp body 36.

In the embodiment of the freewheel 16 shown in FIG. 3, a spring element 44 is provided in each case for each clamping body 36 in comparison with the embodiment of the freewheel 16 shown in FIG. 2, which is hooked into a holding opening 52 provided in the outer ring 22. It is also possible to provide a second spring element for the clamping body 36 in order, for example, to enable a symmetrical shaping, which facilitates assembly. For this purpose, the spring element 44 shown individually in FIG. 4 has a first axial leg 54 and a second axial leg 56, which rest on different axial sides of the clamping body 36 and are connected to one another via a bent connecting piece 58. The connecting piece 58 is inserted in a corresponding recess of the clamping body 36 in order to exert a spring force in the circumferential direction on the guide surface 46 of the guide projection 48. The second axial leg 56 may also abut an axial side of the guide lug 48 to align the clamp body 36 relative to the guide lug 48. The spring element 44 may be hooked in the holding opening 52 via a hook limb 60 and, if appropriate, also bear against an axial side of the clamp body 36.

Bezuaszeichenliste

starter arrangement

drive shaft

block

freewheel

starter wreath

Sprocket carrier

outer ring

camp

seal

bearing seat

outer shaft seal

inner shaft seal

inner ring

clamping bodies

Cage

finger

pressure spring

spring element

guide surface

leadership approach

back

holding opening

first axial leg

second axial leg

joint

hook shank

Claims

claims

Freewheel for a permanently interlocked starter of a motor vehicle, with an outer ring (22) for initiating a starting torque of the starter,

an inner ring (34) for outputting the starting torque to a drive shaft (12), in particular a crankshaft, of an internal combustion engine (14),

between the outer ring (22) and the inner ring (34) arranged in the circumferential direction tiltable clamping bodies (36) and

a spring element (44) acting on the clamping body (36) for providing a radially outwardly directed pressure force on the clamping body (36) against the outer ring (22),

wherein the outer ring (22) has a radially inwardly projecting guide lug (48) for tilting the clamping body (36).

Freewheel according to claim 1, characterized in that the guide projection (48) has a clamping body (36) facing guide surface (46), wherein the clamping body (36) for jamming the outer ring (22) with the inner ring (34) on the guide surface ( 46) is slidable along.

Freewheel according to claim 1 or 2, characterized in that the clamping body (36) between two guide lugs (48) is arranged, wherein the guide lugs (48) each directed towards one another guide surfaces (46, 50), where the clamping body (36) for jamming the outer ring (22) with the inner ring (34) along the guide surfaces (46, 50) is slidable along.

4. freewheel according to one of claims 1 to 3, characterized in that on the clamping body (36) has a spring force in the direction of the guide lug (48) is applied.

5. freewheel according to claim 4, characterized in that the spring force in the direction of the guide lug (48) from the spring element (44) for providing the radially outwardly directed pressure force on the clamping body (36) is applied.

6. freewheel according to one of claims 1 to 5, characterized in that the spring element (44) on at least two clamping body (36), preferably on all clamping body (36), a spring force exerts.

7. Freewheel according to one of claims 1 to 5, characterized in that a separate spring element (44) is provided for each clamping body (36), wherein in particular the spring element (44) in a in the outer ring (22) provided holding opening (52) is hooked ,

8. freewheel according to one of claims 1 to 7, characterized in that the spring element (44) on at least one clamping body (36) and / or on at least one guide lug (48) on one axial side, preferably on both axial sides rests.

9. freewheel according to one of claims 1 to 8, characterized in that a relative to the outer ring (22) movable cage (38) for tilting the clamping body (36) is provided.

10. Starter arrangement for starting an internal combustion engine (14) of a motor vehicle, with a via a freewheel (16) according to one of claims 1 to 9 to the internal combustion engine (14) coupled starter, wherein in particular the inner ring (34) of the freewheel (16) a drive shaft (12) of the internal combustion engine (14) and / or the outer ring (22) by a starter ring (18) of the starter is formed.