GB2335256A

GB2335256A - Stator and freewheel assembly for a torque converter

Info

Publication number: GB2335256A
Application number: GB9824164A
Authority: GB
Inventors: Uwe Dehrmann
Original assignee: Mannesmann Sachs AG
Current assignee: ZF Friedrichshafen AG
Priority date: 1997-11-06
Filing date: 1998-11-04
Publication date: 1999-09-15
Anticipated expiration: 2018-11-04
Also published as: KR100300191B1; FR2770603A1; GB2335256B; KR19990045073A; ES2162541A1; FR2770603B1; GB9824164D0; DE19749043A1; ES2162541B1

Abstract

A stator assembly comprises a set of blades 17 and a hub 21 into which fits an outer ring 31 of a freewheel 29. The hub 21 has an axial projection 39 that projects, towards a pump shell (3, fig 1) beyond an axial extent of the outer ring 31. Inwardly directed elastically deformable webs 41 are arranged at prespecified angles (a, fig 2) around a circumference of the projection 39 and have ends 43 which locate and centre a bearing, eg a needle roller bearing 45 or plain bearing (67, fig 9), and a pressure pad 47 having radial fingers (61, fig 2) which engage between the webs 41. The webs 41 may be of semi-circular or cylindrical cross-section (see figs 4 and 5). The stator is manufactured in a die and axial free faces 53 of the webs 41 act as support surfaces for an ejector to facilitate removal of the stator from the die.

Description

2335256 1 STATOR ASSEMBLY FOR A HYDRODYNAMIC TOROUE CONVERTER The

invention relates to a stator assembly for a hydrodynamic torque converter and a converter incorporating such an assembly.

A stator assembly for a hydrodynamic torque converter is known for example from DE-44 23 640 AI (see in particular Fig. 1). This stator is arranged for radial bearing contact on an outer ring of a freewheel, and surrounds the freewheel outer ring over its entire axial extension. On axial projections, projecting axially on both sides of the freewheel outer ring, the stator is provided with radially inwardly projecting noses which bear on both sides axially on the freewheel outer ring. The freewheel outer ring is thereby secured from axial movement relative to the freewheel inner ring or hub. The freewheel outer ring in turn is guided by clamping bodies on the freewheel inner ring which fits on a hollow shaft mounted between a drive shaft and a converter housing. This arrangement serves to radially centre the stator and also to centre a pressure pad, which lies on one side on the freewheel outer ring. The freewheel is supported on its opposite side on an axial bearing, which in turn bears axially on the pump shell of the converter housing. By means of the axial bearing the freewheel outer ring and thereby the stator is positioned on the side axially adjacent to the converter housing, whereas the stator is held on its opposite axial side by a second axial bearing.

9 4 2 As the fteewheel outer ring is not only responsible for centring the stator but also the reaction pressure pad, the centring proves problematic in particular with respect to the latter, because it is performed in a very narrow space of the torque converter on a relatively small radial diameter. The reaction pressure pad itself is mostly a die casting with a relatively complicated design, as the latter has to engage on the one hand for centring axially in the freewheel and on the other hand must have an axial shoulder for centring the axial bearing. In addition, because of this complicated design of the reaction pressure pad the width is extremely large, especially in the radially inner region, where this is little space anyway.

An object of the invention is to provide a stator assembly in which with the least possible constructive expense as possible and little demand on the axial space requirement improved location of the stator relative to a freewheel is achieved as well as improved location of a pressure pad and/or an axial bearing.

According to the invention there is provided a stator assembly for a hydrodynamic torque converter, said stator assembly comprising a stator hub which radially surrounds a freewheel outer ring over at least one portion along its axial extension, and relative to the freewheel outer ring on at least one axial side thereof has an axially outwardly extending projection and an axial bearing for axially positioning the stator hub relative to a housing of the converter, wherein the projection is provided with mounts distributed at prespecified angles from one another around the circumference, the mounts having radial C v 4 3 inner surfaces projecting radially beyond the inner surface of the portion of the stator hub and so as to locate at least the axial bearing.

By designing the stator hub with an axial projection axially projecting beyond the freewheel outer ring with discrete mounts arranged at prespecified angles around the circumference, the stator hub can be produced with a smaller wall thickness on both sides of the mounts in the region of the axial projection. This is an advantage in particular on making the stator and thereby the stator hub from thermoplastic material for better manufacturability, On the other hand however, in the region of the mounts there is sufficient resistance to deformabdity so that the latter with their radial inner surfaces can at least centre the axial bearing. For this, the mounts project radially inwards with their radial inner surfaces over the circumferentially adjacent regions on the stator hub and mount the axial bearing at prespecified points around the diameter. The mounts can in this way be designed in one piece with the adjacent axial projection of the stator hub and thereby resist a high radial resistance to deformability of the axial bearing. The mounts can also be securely fastened at the axial end facing the stator hub to the stator hub and otherwise run at a prespecified distance from the radial inner surfaces of the stator hub. In this way, elasticity of the mounts is produced in a radial direction, which in particular on using an inherently elastic material can produce optimum results. Because of this design of the mounts an axial bearing, and if necessary a pressure pad acting therewith, can be clamped radially by the mounts, so that in a simple manner a force-closed connection between the stator hub and the pressure pad andlor the axial 0 A 4 4 bearing can be produced without a form closure being necessary for rotational securing. In addition, rotation-fast connections between the pressure pad and the stator hub are possible, in that radial projections are provided on the pressure pad, of which two engage on both sides of a mount without play in the circumferential direction.

The mounts can also have an additional function resulting from the manufacture of the stator, provided that the latter is produced by means of an injection moulding process using a thermoplastic material. For this a die with at least two die halves is required which has chambers for filling with the moulding material. Once the injected material has hardened after cooling the two die halves are separated axially. For this process, one die half is lifted axially and afterwards the stator is pressed out of the latter by axially moving ejectors, which are provided on the other die half These known ejectors can be positioned in such that the free ends of the mounts act as support surfaces for the ejectors.

The afore-mentioned pressure pad, which is preferably provided axially between the freewheel outer ring and the axial bearing and serves to absorb pressure forces and protect the relatively sensitive axial bearing, can be designed as a punched sheet steel washer, which is made ideally without plastic deformation. With one axial side abutting on the freewheel outer ring the pressure pad can be positioned with its other axial side on the axial bearing.

F The outer circumference of a pressure pad designed in this way can be positioned on the radial inner side of the mounts, so that the pressure pad, like the adjacent axial 1 bearing, is centred respectively by the mounts relative to the other converter components.

According to a further embodiment also the radially outer region of the pressure pad can be bent in an axial direction, in order to be centred on the one hand with its outer circumference on the mounts of the stator hub, and on the other hand to centre the axial bearing with its inner diameter. Thereby with little overall constructive expense an extremely space-saving design can be achieved in the radial region of the freewheel.

The invention may be understood more readily, and various other features of the invention may become apparent, from consideration of the following description.

Embodiments of the invention are explained in more detail by way of examples and with reference to the accompanying drawings wherein:

Figure 1 is a sectional view of the top half of a hydrodynamic converter employing a stator assembly constructed in accordance with the invention; 9 4P 6 Figure 2 is an axial cross-sectional view of the stator assembly taken along the line 11-H of Fig. 1, with mounts of square cross section projecting beyond the radial inner surfaces of the stator hub.

Figure 3 is a section taken along the line III-III of Figure 2-, Figure 4 is a view corresponding to Figure 2 but with a modified construction with mounts of semi-circular cross section- Figure 5 is a view corresponding to Figure 2 but with a modified construction with mounts of cylindrical cross section spaced apart from the radial inner region of the stator hub., Figure 6 is an axial end view of a pressure pad used in the converter and its stator; Figure 7 is a cross-section of the pressure pad shown in Figure 6, the view being taken along the line VII-VII of Figure 6; Figure 8 is a view corresponding to Figure 1 but utilizing a pressure pad with an axial shoulder in its circumferential region; 1 0 7 Figure 9 is a view corresponding to Figure 1 but utilizing an axial bearing as a sliding bearing instead of pressure pad and Figure 10 is a sectional view of a die with ejectors used for manufacture of the stator.

In Figure 1 the region of a hydrodynamic torque converter is highlighted in which a stator is arranged. The torque converter has not been illustrated and described as a whole, as such torque converters are known from the prior art, for example from the aforementioned DE 4423 640 AI.

A small section of a converter housing 1 is shown by way of a pump shell 3 which is part of a pump impeller 5. The latter operates together with a turbine wheel 7, by which hydraulic fluid is supplied via a stator 9 to the pump impeller 5. The turbine wheel 7 is secured by means of rivets 11 to a turbine hub 13 which via toothing 15 on its inner diameter is rotationally locked to a driven shaft (not shown).

The stator 9 has a set of blades 17 on a stator hub 21, and the free ends of the blades 17 are secured to one another by a connecting ring 19. The stator hub 21 in turn is secured to an outer ring 31 of a freewheel 29. The freewheel outer ring 31 is connected by clamping bodies 33 to a freewheel inner ring '15. On its inner diameter, the inner ring 35 has toothing 37, with which it engages with a hollow shaft (not shown) for 9 4 8 rotation therewith. The hollow shaft extends radailly between the driven shaft and a driven-side sleeve 5 1, which is secured to the pump shell 3.

On its side facing the turbine hub 13, the stator hub 21 is associated with an axial sliding bearing 23, provided with grooves 25 for the passage of hydraulic fluid for the converter circuit. The hydraulic fluid can be fed radially through an intermediate space between the hollow shaft and the drive shaft.

The stator hub 21 has on its side facing the pump shell 3) an axial projection 39. As shown in Figures 2 and 3, the projection 39 has a relatively small radial cross section. In a peripheral direction the projection 39 has inwardly extending mounts 41 spaced apart at prespecified angles cc one ftom another. In this construction, the mounts 41 are in the form of webs 5 5 extending inwardly from the radial inner surface 46 of the stator hub 2 1.

The webs 55 are of a rectangular cross section. As shown in particular in Figure 3), the radial inner surfaces 43 of the mounts 41 serve to mount both a pressure pad 47 and an axial bearing 45 in the form of roller bearing 49. The bearing 49 is centred only on the radial inner surfaces 43 of the mounts 41. The pressure pad 47 is also centred by the mounts 41 but in addition the pressure pad 47 can also be rotationally locked to the stator hub 21. For this purpose, the pressure pad 47 can have radial projections 67 which engage circumferentially between the mounts 41 in a keyed manner. The pressure pad 47 is here designed as a simple plastically undeformed component and is preferably 9 9 punched out of sheet steel. The cost of such a pressure pad is minimal and the axial space it occupies is minimal.

Figure 4 shows a different embodiment of the mounts 41 with a semicircular cross-section. The mounts 41 again project radially inwards relative to the radial inner surface 46 of the hub 21. The innermost regions of these semi-circular mounts 41 with the closest radial proximity to a central axis 72 act as the radial inner surfaces 43 of the mounts 41, to perform the function of locating and centring of the pressure pad 47 and the axial bearing 45. In contrast to the embodiment according to Figure 2, the surfaces for bearing the pressure pad 47 and the axial bearing 45 are reduced in size but their effectiveness is not impaired.

Another construction for the mounts 41 is shown in Figure 5 and in this case the mounts 41 have a cylindrical cross section. Whereas the mounts 41 according to Figures 2 and 4 ensure a rigid mounting of the pressure pad 47 and the axial bearing 45 in a radial direction, the mounts 41 according to Figure 5 are designed to be flexible and may be hollow. The cylindrical mounts 41 have their regions facing the stator hub 21 in one piece with the stator hub 21 and extend by a distance from the radial inner surface 46 of the stator hub 21 to permit elastic deflection in the direction of the radial inner surface 46 of the stator hub, whereby the latter acts as a stop for the mounts 4 1. With the axial insertion of the pressure pad 47 and the axial bearing 45 the mounts 41 can be deflected radiaIly outwards, but because of the thus produced preloading, both the pressure pad 47 1 4 and the axial bearing 45 are held. Because of this inherent force-closure the provision of radial projections 61 is unnecessary and a rotation-fast connection between the stator hub 21 and the pressure pad 47 is still maintained.

According to Figures 2, 4 and 5 the axial free faces 53 of the mounts 41 can be used as support surfaces 60 for an ejector 59 of a die shown in Figure 10. For this, the stator hub 21 with the blades 17 and the connecting ring 19 and the simultaneously injected freewheel outer ring 31 is positioned in the die half 57. The other die half has already been removed. For a simplified removal of the stator 9 from the die half 57 the ejectors 59 are moved to the left in the axial direction according to Figure 10 until they exert an axial force on the support surfaces 60 of the mounts 41 and in this way press the stator 9 out of its chamber in the die half 57, Figures 6 and 7 show a pressure pad 47 as a single unit as used in the embodiment of the stator hub 21 with the mounts 41 according to Figure 2. The radial projections 61 are illustrated clearly on both sides of a circumferential region 62. In connection with a stator hub 21 according to Figure 5 the radial projections 61 can be omitted. In the embodiment according to Figure 4, the circumferential regions 62 for adjusting to the shape of the mounts 41 are designed to be semi-circular.

Figure 8 differs from Figure 1, in that the pressure pad 47 in its circumferential region has a bend in the axial direction, by which an axial shoulder 63 is formed. This 1 -0 11 shoulder 63 is supported with its outer circumference on the radial inner surfaces 43 of the mounts 41 and with its radial inner surface 65 forms a centring for the axial bearing 45. The axial shoulder 63 of the pressure pad 47 can be formed by punching the latter out of sheet steel and with this design there is no additional manufacturing cost.

In contrast to the previously described Figures, in which the axial bearing 45 is actually the roller bearing 49, according to Figure 9 an axial sliding bearing 67 is provided, which is designed with grooves 69 through which lubricating hydraulic fluid flows to improve its sliding properties. In contrast to the roller bearing 49, the sliding bearing 67 requires no pressure pad on the stator side, and the axial sliding bearing 67 is centred on the inner surfaces 43 of the mounts 41 as before.

1 4 12 List of Reference Numbers 1.

converter housing 3. pump shell pump impeller turbine wheel stator 5. 7. 9. 11. rivets 13. turbine hub 15. toothin., 17. blades 19. 21. 23. 25. 27. 29. 31. 33.

37. 39.

connecting ring stator hub axial sliding bearing grooves axial ring freewheel freewheel outer ring freewheel clamping bodies freewheel inner rincr toothing projection 4 1 1 J 41. mounts 43. radial inner surfaces of mounts 45. axial bearing 46. 47. 49.

radial inner surfaces of stator hub pressure pad roller bearing sleeve axial free faces of mounts webs die ejector support surfaces 53. 55. 57. 59. 60. 61. radial projections 62. circumferential region 63. axial shoulder 65 radial inner surface of the axial shoulder 67. axial sliding bearing 69. grooves 72. central axis 1 0 14

Claims

Claims

1. A stator assembly for a. hydrodynamic torque converter, said stator assembly comprising a stator hub (21) which radially surrounds a freewheel outer ring (3 1) over at least one portion along its axial extension, and relative to the freewheel outer ring on at least one axial side thereof has an axially outwardly extending projection (39) and an axial bearing (45) for axially positioning the stator hub relative to a housing (1) of the converter; wherein the proejction (_39) is provided with mounts (41) distributed at prespecified angles (cc) from one another around the circumference, the mounts (41) having radial inner surfaces (43) projecting radially beyond the inner surface (46) of the axial portion of the stator hub (2 1) and so as to locate at least the axial bearing (4 5).

2. A stator assembly according to claim 1, wherein the mounts (41) are formed by webs (55) projecting radially inwards from the axial projection (39)- 3. A stator assembly according to claim 1 or 2, wherein each of the mounts (41) is securely fastened at one connection with the stator hub (21) and the connections are selected so that the mounts (41) are arranged at a prespecified distance from the radial inner surface (46) of the stator hub (2 1).

A stator assembly according to claim 3, wherein the mounts (41) are deformable elastically in the radial direction.

r 4 5. A stator assembly according to claim 1 or 2, wherein the mounts (41) are of rectangular or semi-circular cross-section.

6. A stator assembly according to claim 4, wherein the mounts are of cylindrical cross-section.

7. A stator assembly according to any one of claims 1 to 6 and manufactured by being arranged in a die and for removal from said die is loaded by axially moving ejectors wherein the axial free faces (53) of the mounts (41) act as support surfaces (60) for the ejectors (59).

8. A stator assembly according to any one of more of claims 1 to 7 and further comprising a pressure pad (47) associated with the axial bearing, the pressure pad being positioned at least by the axial bearing and the freewheel outer ring.

9. A stator assembly according to claim 8, wherein the pressure pad (47) is positioned by the mounts (4 1).

11. A stator assembly according to claim 8 or 9, wherein the pressure pad (47) is a punched steel sheet washer.

9 4 16 10. A stator assembly according to claim 9, wherein the pressure pad (47) comprises radial projections (61) which engage between the mounts (41) in a keyed manner.

12. A stator assembly according to claim 8,9,10 or 11 wherein the axial bearing (45) is centred on the mounts (41) of the stator hub (21) by means of an axial shoulder (63) of the pressure pad (47) supported radially on the mounts (41) the axial bearing (45) engaging on the radial inner side (65) of the axial shoulder (63).

13. A stator assembly according to claim 12, wherein the axial shoulder (63) is formed by bending the radially outer region of the pressure pad (43) in an axial direction.

14. A stator assembly substantially as described herein with reference to and as illustrated in any one or more the Figures of the accompanying drawings.

A hydrodynamic torque converter incorporating a stator assembly according to any one of the preceding claims.

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