FR2837544A1 - Ball bearing and control device for returning emissions in a combustion engine, has first ring made of unformed sheet metal, a second ring, and a carrier with a tapering tubular sleeve - Google Patents

Abstract

The bearing device has a first ring (3) of unformed sheet metal, a second ring (4) and roller bodies (5) arranged axially between the two rings. The device has a one piece carrier (2) with a base (6) in contact with the second ring. In the axial direction, the base is on the side of the second ring furthest from the first ring. The base (6) has a radial locating surface (7) aligned with the side facing the second ring. The base also has a bore (10). The carrier has a tapering tubular sleeve (13). The first ring has a radial bearing section on the other side of the roller body. The first ring has a radial holder section axially spaced from the bearing section and surrounding the sleeve. The sleeve has an axial holder which cooperates with the radial holder section to prevent axial separation of the rings. Independent claims also cover an emissions return valve for a combustion engine, comprising a bearing device.

Description

Bearing stop device and gas recycling control valve

  exhaust comprising such a device.

  The present invention relates to a rolling stop device, and a control valve comprising such a device, in particular a control valve.

  for recycling exhaust gas from an internal combustion engine.

  Efforts are being made by car manufacturers to reduce polluting emissions from internal combustion engines, and in particular emissions of nitrogen oxides (NOx). Exhaust gas recycling valves allow a part of the exhaust gases to be taken and the sampled exhaust gases to be returned to the intake. These are generally inert and do not participate in combustion. Their admission into the cylinders decreases the quantity of admitted gas participating in the combustion, and thus makes it possible to decrease the combustion temperature, which has the effect of reducing the rate of nitrogen oxides

  1S present in the exhaust gas.

  Document FR 2 744 492 discloses a recycling valve comprising a valve the rectilinear closing or opening movement of which is controlled by an electric motor with a rotating magnet and a lifting system converting the movement rotary of the electric motor in rectilinear movement. The rotor of the electric motor is linked in rotation to the stator by means of two distant needle bearings, and an axial bearing stop. A first needle bearing is disposed between a rotary axis and a bore of a non-rotating ring of the axial stop, the needles coming into direct contact on the axis and on the bore. The needle bearing ensures free rotation of the rotor relative to the stator. The axial stop retains a defined air gap between the rotor and

the stator.

  When mounting the electric motor, it is necessary to arrange the axial stop and the first needle bearing in a precise order, which makes an assembly operation complicated. In addition, the axial stop and the needle bearing comprise separate elements which are assembled during assembly of the electric motor. I1 there is a risk of improper handling of the axial stop or the needle bearing which can lead to the loss of an element, such as a rolling element. In addition, it is necessary to manage the supply and storage on the one hand of the axial stop and its parts and on the other hand of the needle bearing and its parts. Furthermore, it is desired to obtain a compact recycling valve. Stop

  axial surrounding the needle bearing has a large radial size.

  S The needle bearing has a large axial dimension, requiring

  special arrangements for the rotor and stator.

  The present invention relates to a rolling stop device capable of withstanding axial and radial forces, and being in the form of a pre-mounted assembly to facilitate its transport and its mounting in a mechanical assembly. The invention also relates to a rolling stop device comprising a limited number of parts, easy to assemble and to handle, and of cost.

weak manufacturing.

  The subject of the invention is also a compact bearing stop device 1S axially and radially to facilitate its integration into a mechanical assembly.

  compact, like an exhaust gas recycling valve.

  Such a rolling stop device comprises a first ring made of pressed sheet metal, a second ring, rolling elements disposed axially between the first and second rings, a support comprising a base in contact with the second ring, and disposed axially on the side opposite to the first ring, the base having a radial bearing surface on the side opposite to the second ring, and a sleeve extending axially from the annular base towards the first ring, the first ring comprising a radial stop portion located axially at one end of the first ring, on the side of the rolling elements opposite the second ring. The first ring further comprises a radial retaining portion extending inwardly and lying at an axial distance from the radial abutment portion, the sleeve comprising axial retaining means cooperating with the radial retaining portion to prevent movement distance from the first ring

compared to the second ring.

  The support makes it possible to obtain a pre-mounted bearing stop device, not risking being dismantled during its manipulation by an operator. It also facilitates the management of its supply. The rolling stop device can be easily mounted in a single operation. The support comprises an annular base axially retaining the second ring and a sleeve comprising means for axially retaining the first ring. The sleeve retaining means are adapted to allow easy mounting of the rolling stop device by allowing axial approximation of the first and second rings. The rolling stop device comprises a monobloc support provided with a radial bearing surface allowing a direct transmission of forces, which limits the number of parts of the rolling stop device, facilitates assembly and design, and allows to ensure the radial and axial compactness of the stop device to

  bearing to facilitate its integration into a mechanical assembly.

  In one embodiment, the retaining means comprise a surface cooperating with the radial retaining portion to cause an elastic radial deformation of the retaining means during mounting of the first ring on the sleeve. Preferably, the radial abutment portion has a front abutment surface lying beyond a free end of the sleeve opposite the base. This ensures the axial compactness of the rolling stop device. The front abutment surface can come into axial contact directly on a radial bearing surface without it being necessary to provide a housing allowing the passage of the free end

of the sleeve.

  In one embodiment, the sleeve includes a radial allowance. The radial allowance ensures retention of the first ring by radial interference with an inner edge of the retention portion of the first

  ring, during an axial separation of the first and second rings.

  Advantageously, the radial allowance has an inclined surface. The inclined surface facilitates the mounting of the first ring by causing a radial force directed inwards on the sleeve when an axial force is applied to the first ring for the axial approximation of the first and second rings and that the inner edge of the radial retaining portion is pressed axially against the excess thickness. The radial force allows the elastic radial deformation of the sleeve,

  authorizing the axial passage of the radial retaining portion and the ring.

  Preferably, the radial retaining portion of the first ring is located axially between the radial abutment portion and the base. The sleeve cooperates with a radial retaining portion offset axially relative to a bearing portion of the first ring, by being closer to the base. The sleeve has a limited length, which thus limits the axial size of the stop device to

  bearing and facilitates its integration into a compact mechanical assembly.

  In one embodiment, the first ring comprises a cylindrical axial portion surrounding the rolling elements. The cylindrical axial portion surrounding the rolling elements allows a transmission of radial forces by the second ring, the rolling elements coming into contact on an inner surface of the cylindrical axial portion. The cylindrical axial portion protects the space between the first and second rings. The cylindrical axial portion also allows the radial positioning of the first ring in a housing. The rolling stop device then also ensures the radial positioning between two parts of a mechanical assembly. The cylindrical axial portion allows the formation of an external cylindrical bearing surface while retaining the radial compactness, and the

  axial compactness, since the cylindrical axial portion surrounds the rolling elements.

  The inner surface of the cylindrical axial portion can serve as a surface for

  bearing for rolling elements.

  In one embodiment, the first ring comprises a toroidal portion having an internal raceway. The raceway preferably has an internal shortening radius substantially equal to the radius of curvature of the contact surfaces of rolling elements for extended contact between the rolling elements and the toroidal portion, ensuring better force transmission.

  axial and radial between the elements and the first ring.

  In one embodiment, the first ring has an outside diameter substantially equal to the outside diameter of the base, which ensures the radial compactness of the rolling stop device and facilitates its integration into

a mechanical assembly.

  The invention also relates to an internal combustion engine exhaust gas recycling valve comprising an electric control motor provided with a stator, a rotor carrying a magnet and situated on an axially first side of the stator and d '' an actuation shaft integral with the rotor, the rotor and the shaft being mounted for rotation relative to the stator by means of a device

  of a rolling stop according to any one of the preceding claims, the

  Rolling stop device being disposed axially between the rotor and the stator, and defining a given axial air gap between the rotor and the stator The present invention and its advantages will be better understood on studying the

  detailed description of embodiment taken by way of nonlimiting example

  and illustrated by the appended drawings, in which: FIG. 1 is a view in axial section of a first embodiment of a rolling stop device according to an aspect of the invention; FIG. 2 is a view in axial section of a second embodiment of a rolling stop device; and FIG. 3 is a view in partial axial section of a recycling valve for

  exhaust from an internal combustion engine.

  In FIG. 1, a rolling stop device referenced 1 as a whole comprises a monobloc support 2 of generally annular shape, a first ring 3, a second ring 4 bearing on the support 2, and

  rolling element 5 disposed axially between the first and second rings 3, 4.

  The support 2, made of synthetic material such as a polyamide, comprises an annular base 6 having a radial bearing surface 7. The base 6 is provided with an external portion 8 and an internal portion 9 thicker axially, and doing

  projection relative to the external portion 8 on the side opposite to the radial bearing surface 7.

  The internal portion 9 has a bore 10, a radial surface 11 opposite the radial support surface 7 and an external surface 12 of revolution continuously connecting the radial surface 11 to the external portion 8. The external portion 8 has a diameter external greater than the diameter of the circle passing through the centers of the rolling elements S. A tubular axial portion in the form of a sleeve 13 is connected to the base and extends axially on the side opposite to the radial bearing surface 7 from an area of smaller diameter of the inner portion 9 of the base 6. The inner surface of the sleeve 13 axially extends the bore 10 of the inner portion 9. The sleeve 13 comprises at its free end retaining means , in the form of hooks 14, of which only one is visible in FIG. 1. A hook 14 locally forms an external radial allowance on an external surface 1S of the sleeve 13. The hook 14 has a surface inclined 14a, oriented radially outwards and on the side opposite to the base 6, and a surface

  substantially radial 14b oriented towards the side of the base.

  The second ring 4 is made of sheet metal, formed for example by stamping, and has in axial section a profile substantially in a quarter of a circle. The second ring 4 is in contact with the external surface 12 of the base 6 and partially surrounds the internal portion 9. The second ring 4 extends from the external portion 8 to the external surface 11 of the internal portion 9 of the base 6. The second ring 4 has a toroidal raceway 16 with concavity oriented on the side opposite to the base 6 and radially outward. The rolling elements S are intended to come into contact on the toroidal raceway 16. A free end 4a of the second ring 4 is located substantially in the radial plane passing through the center of the rolling elements 5, being axially offset from the side of the base. The opposite free end 4b of the second ring 4 has an outside diameter greater than the diameter of the circle passing through the center of the rolling elements S. The second ring 4 is therefore adapted to withstand axial and radial forces transmitted by the rolling elements S. The first ring 3 includes is also made of sheet metal and form for example

  by stamping. The first ring 3 has the general shape of an annular cup.

  The first ring 3 comprises a radial stop portion 17 located on the side of the rolling elements S opposite the second ring 4, an axial extension 18 extending from a zone of smaller diameter of the radial stop portion 17 on the side rolling elements S. and a radial retaining portion 19 extending inwards from the end of the axial extension 18 opposite the radial abutment portion 17,

  and surrounding by its bore l9a the sleeve 13.

  The first ring 3 also comprises an axial portion 20 surrounding the rolling elements 5, and connected to a zone of larger diameter of the radial abutment wall 17 by a toroidal portion 21 with concavity oriented towards the rolling elements 5. The axial portion 20 has an outer diameter substantially equal to the outer diameter of the base 6. The toroidal portion 21 has in section a profile substantially in a quarter circle. The toroidal portion 21 has an inwardly oriented toroidal raceway 22, with a radius of curvature substantially equal to the radius of curvature of the contact surfaces of the rolling elements S. The radial abutment portion 17 is located in a radial plane tangent to the rolling elements, which

  ensures the axial compactness of the rolling stop device.

  The axial extension 18 of the first ring 3 has an axial length such that the free end of the radial retaining portion 19 is located axially between the hooks 14 and the internal portion 9 of the base 6 when the first ring is in contact with the rolling elements S in contact on the opposite side with the second ring 4. The radial retaining portion 19 is axially offset with respect to the radial abutment portion 17, on the side of the rolling elements 5. The radial retaining portion 19

  is located substantially in the radial plane passing through the center of the rolling elements 5.

  The radial retaining portion 19 has an inside diameter smaller than the outside diameter of the sleeve hooks 13 in the free state. The outer diameter of the hooks 14 is greater than the diameter of the bore 19a of the radial retaining portion 19, so that there is a radial interference between the hooks 14 and the

  radial retaining portion 19 when the sleeve 13 is in the free state.

  The free end of the sleeve 13 is situated substantially in the same radial plane as a front abutment surface 17a of the radial abutment portion 17 located on the side opposite to the rolling elements 5. The free end of the sleeve 13 is slightly

  offset from the side of the base 6 relative to the front abutment surface 17a.

  The axial extension 18 has an inner diameter greater than the diameter of a

  cylindrical surface surrounding the hooks 14 of the sleeve 13.

  The first ring 3 is suitable for oblique contact with the rolling elements 5 by its toroidal portion 21. The second ring 4 is also suitable for oblique contact with the rolling elements 5. The rolling stop device 1

  therefore allows the transmission of radial and axial forces.

  The second ring 4 is in contact with the base 6 via the external portion 8 and the internal portion 9 which it surrounds. The base 6 therefore allows a transmission and a distribution of the axial and radial forces towards respectively - the radial bearing surface 7 and the bore 10 of the base 6. The second ring 4 is simple and can be obtained by a number limited operations. These characteristics

  limit the manufacturing cost of the rolling stop device 1.

  When mounting the rolling stop device 1, the rolling elements 5 are placed in the first ring 3, the latter being arranged to bear on its front stop surface 17a oriented downwards. The rolling elements 5 are then capped with the second ring 4 and the sleeve 13 of the support 2 is introduced axially through the first and second rings 3, 4. The radial retaining portion 19 comes into contact with the inclined surfaces 14a of the hooks 14. The sleeve 13 is pressed axially, which causes the formation of radial forces applied to the sleeve and directed inwards, due to the inclination of the surfaces 14a of the hooks 14. The radial forces cause a deformation of the sleeve 13 with a decrease in the diameter of its free end, allowing the hooks 14 to pass axially through the radial retaining portion 19. When the sleeve 13 is sufficiently axially inserted so that the hooks 14 are located on the side of the radial retaining portion 19 opposite the base 6, the hooks 14 are released and the sleeve 13 returns to its initial shape. In the position reached, the free end of the sleeve 13 carrying the hooks and surrounded by the axial extension 18 of the first ring 3. The axial extension 18 having an internal diameter greater than the external diameter of the hooks 14 allows the latter to

  return to their initial position corresponding to the free state of the sleeve 13.

  Once the bearing stop device is mounted, during an axial movement away from the first and second rings 3, 4, the radial retaining portion 19 comes to bear against the radial surface 14b of the hooks 14. The application of 'an axial force on these radial surfaces 14b does not allow a radial deformation of the sleeve 13 allowing the passage of the radial retaining portion 19. The sleeve retaining means 13 prevent involuntary disassembly of the first and second rings 3, 4. Good understood, any suitable retaining means other than hooks may be suitable, as long as they allow radial interference with the radial retaining portion 19, by allowing a movement of approaching the rings, and by prohibiting a reverse axial movement. In a variant, the hooks 14 can be replaced by a bead or a circumferential rib projecting radially relative to the sleeve 13, said rib being able to be continuous

  or discontinuous in the cTrconferential direction.

  In another variant, the free end of the radial retaining portion 19 can extend obliquely inwardly, on the side of the radial abutment portion 17, by presenting an inclined surface oriented inwardly and on the opposite side to the radial abutment portion 17. Such an inclined surface facilitates the passage of one end of the sleeve 13 having a radial excess thickness by causing a

  radial deformation of the free end of the sleeve 13 during assembly.

  The rolling stop device 1 forms a non-removable assembly, which can easily be integrated into a mechanical assembly. There is no risk of an operator disassembling the rolling stop device 1 during improper handling. The free end of the sleeve 13 is axially set back with respect to the front stop surface 17a of the radial stop portion 17 of the first ring 3. Thus, the front stop surface 17a can come into contact with a surface d 'corresponding support, without the need to provide a particular axial housing for the free end of the sleeve 13. The radial retaining portion 19 offset from the radial abutment portion 17 allows to limit the axial length of the sleeve 13 , while forming hooks 14, and more generally retaining means, capable of retaining the first ring 3 without coming into axial projection relative to the front abutment surface 17a. The rolling stop device 1 is axially compact. The assembled rolling bearing can also be easily manipulated without the risk of catching the free end of the sleeve 13, which promotes the automation of the transfer of the assembled rolling bearings to and on a final mounting station of said rolling bearings in the mechanical assembly

who receives them.

  The sleeve 13 passing through the retaining portion 19 extends the bore 10 of the internal portion 9 of the base 6. The sleeve 13 allows better guidance of the support 2 and therefore of the second ring 4 on a shaft adjusted in the bore 10. The sleeve 13 also participates in the distribution of the radial forces taken up by the second ring 4, to transmit them towards said shaft. The distribution of the radial forces, as well as the axial forces towards the radial bearing surface 7, and obtained by means of the support 2, allows the use of a support 2 of overmolded synthetic material, without annoying axial deformation of the rolling bearing device. One can in particular use a synthetic material having stiffness characteristics allowing the radial deformation of the free end of the sleeve 13 during the

  mounting the rolling bearing device 1.

  The base 6 has a flat rear radial support surface and the radial stop portion 17 of the first ring 3 is located in a radial plane flush with the rolling elements S. so that the rolling stop device 1 is axially compact while allowing transmission of axial and radial forces. The external portion 8 of the base 6 having an external diameter greater than the diameter of the circle passing through the rolling elements improves the transmission of forces

axial directly through the base 6.

  In Figure 2, references to elements similar to Figure 1 have been repeated. A rolling stop device 1 is identical to the device illustrated in FIG. 1 except that the first ring 3 comprises a toroidal portion 21 having an inner radius of curvature less than the radius of curvature of the surfaces

  rolling element contact 5.

  The rolling elements S come into radial contact with a cylindrical inner surface 20a of the axial portion 20, and in axial contact with a radial rolling surface 17b of the radial abutment wall 17, opposite to the radial surface

stop 17a.

  In this embodiment, it is not necessary to form the toroidal portion 21 with a given internal radius of curvature, substantially equal to the radius of curvature of the contact surfaces of the rolling elements S. The manufacturing tolerances being greater, the first ring 3 can be obtained with a lower manufacturing cost, thereby lowering the manufacturing cost of the rolling bearing device 1. The first ring 3, in radial and axial contact with the rolling elements S. still allows transmission radial and axial forces by the

rolling stop device.

  The rolling stop device can be used in an exhaust gas recycling valve of a motor vehicle. In FIG. 3, a recycling valve referenced 25 as a whole comprises a casing 26, a cover

  27, an electric motor 28 and an actuation shaft 29.

  The casing 26 comprises a cylindrical casing 30 having a bore a, and a bottom portion 31 extending radially inward, and having a central opening 31a. The cover 27 comprises an axial skirt 32, one free end of which comes into axial contact with the free end of the cylindrical casing 30 opposite the bottom portion 31. The axial skirt 32 has at said free end an axial centering rib 33 adjusted in bore 30a of

the cylindrical casing 30.

  The electric motor 28 comprises a stator 34 housed in the casing 26 while being adjusted in the cylindrical casing 30 until it comes into axial contact with the bottom wall 31. The stator 34 is provided with a central bore 35. The motor electric 28 includes a rotating part 36 comprising a rotor 37 located on the side of the stator 34 opposite the bottom portion 31, and bearing on an area of larger diameter

  magnets 38 arranged on the side of the stator 34.

  The rotor 37 is linked in rotation to the actuating shaft 29 which passes through the rotor 37, the bore 35 of the stator 34 and the opening 31a of the bottom portion 31. The shaft 29 carries at its end projecting of the casing 26 a lifting beam 39 for controlling the axial movement of an exhaust gas recycling valve, not shown, by a rotary movement of the lifting beam 39. A smooth bearing 40 is disposed between the shaft 29 and the bore 35 of stator 34, being located axially close to the

bottom portion 31.

  A rolling stop device 1 is arranged between the stator 34 on the one hand, and the rotor 37 and the shaft 29 on the other hand. The first ring 3 is adjusted in an annular housing 41 formed at the end of the stator 34, and having an axial cylindrical bearing 42 and a radial bottom wall 43. The first ring 3 is supported by its axial portion 20 with the bearing cylindrical 42 and not its radial stop wall 17 with the radial bottom wall 43. The axial portion 20 of the first ring allows the radial positioning of the first ring relative to the stator 34. The support 2 is adjusted on the shaft 29 by its bore 10, the radial bearing surface 7 of

  the base 6 coming to bear axially on the rotor 37.

  The rolling stop device 1 supports the axial and radial forces between on the one hand the rotor 37 and the shaft 29 and on the other by the stator 34. The central portion 8 and the sleeve 13 allow radial positioning of the shaft and a transmission of radial forces. The cylindrical axial portion 20 of the first ring of the rolling bearing device 1 ensures the radial positioning of the first ring 3 relative to the stator 34, and consequently the maintenance of the relative radial position between the stator and the shaft 29. The base 6 allows the transmission of axial forces between the stator 34 and the rotor 37. The base 6 also ensures, by friction contact, the rotational connection of the shaft 29 and of the second ring 4. The stop device rolling allows to maintain a given axial distance, that is to say a given air gap, between the magnets 38 and the stator 34, to maintain an identical operation of the electric motor, and to be able to control an axial displacement

  precision of a recycling valve not shown.

  The rolling stop device is axially and radially compact to maintain the compactness of the recycling valve as a whole. The sleeve 13 of the support 2 does not protrude axially relative to the radial abutment surface 17a of the radial abutment wall 17 of the first ring 3, so that it

  it is not necessary to provide a housing for the free end of the sleeve 13.

  Thanks to the invention, a simple rolling stop device is obtained which has a simple manufacturing cost. The rolling stop device is also compact, and supports radial and axial forces. The rolling stop device is in the form of a pre-assembled and non-removable assembly, capable of

  easily to be handled, and easily inserted into a mechanical assembly.

Claims (10)

  1. Rolling stop device comprising a first ring (3) made of pressed sheet metal, a second ring (4), rolling elements (5) disposed axially between the first and second rings (3,4), characterized in that '' it comprises a support (2) in one piece comprises a base (6) in contact with the second ring (4), and disposed axially on the side of the second ring (4) opposite to the first ring (3), the base ( 6) having a radial bearing surface (7) oriented on the side opposite to the second ring (4), and a sleeve (13) extending axially from the base (6) towards the first ring (3), the first ring (3) comprising a radial stop portion (17) located axially at one end of the first ring (3), on the side of the rolling elements (5) opposite to the second ring (4), the first ring comprising a radial retaining portion (19) lying at an axial distance from the radial abutment portion (17), the sleeve (13) comprising axial retaining means (14) cooperating with the radial retaining portion (19) to prevent a movement of axial separation from the   first ring (3) relative to the second ring (4).   2. Device according to claim 1, characterized in that the retaining means (14) comprise a surface (14a) cooperating with the radial retaining portion (19) to cause a radial deformation of the retaining means (14) during   mounting the first ring (3) on the sleeve (13).   3. Device according to any one of claims 1 or 2, characterized   in that the radial stop portion (17) has a front stop surface   (17a) lying beyond a free end of the sleeve (13) opposite the base (6).   4. Device according to any one of the preceding claims,   characterized in that the sleeve (13) comprises at least one radial allowance (14).   5. Device according to claim 4, characterized in that the radial allowance (14) has an inclined surface (14a) oriented towards the outside and on the side opposite the base (6).   6. Device according to any one of the preceding claims,   characterized in that the radial retaining portion (19) is located axially between the   radial stop portion (19) and the base (6).   7. Device according to any one of the preceding claims,   characterized in that the first ring (3) comprises an axial portion (20)   cylindrical surrounding the rolling elements (S).   8. Device according to any one of the preceding claims,   characterized in that the first ring (3) comprises a toroidal portion (21)   having an internal raceway.   9. Device according to any one of the preceding claims,   characterized in that the first ring (3) has an outside diameter   substantially equal to the outside diameter of the base (6).   10. Internal combustion engine exhaust gas recycling valve comprising an electric control motor provided with a stator, a rotor carrying a magnet and situated on an axially first side of the stator and a shaft d actuation integral with the rotor, characterized in that the rotor and the shaft are mounted for rotation relative to the stator by means of a stop device at   bearing according to any one of the preceding claims, the device for   rolling stop being disposed axially between the rotor and the stator, and defining a