Sprag freewheel with securing device
Patent Information
- Application Number
- EP2024794105
- Authority / Receiving Office
- EP · EP
- Patent Type
- Applications
- Current Assignee / Owner
- Priority Date
- 2023-10-30
- Filing Date
- 2024-10-18
- Publication Date
- 2026-09-09
AI Technical Summary
Existing clamping body exemptions with safety devices are complex and difficult to manufacture, particularly due to the need for precise processing of radial flanges to ensure a torque-stiff connection.
A clamping body exemption with a safety device featuring a wreath of projections axially advanced from the outer ring, which can be produced through a deep-drawing and punching process, simplifying the manufacturing process and enhancing torque resistance.
The proposed solution simplifies the manufacturing process while maintaining or improving the torque resistance, making it easier to produce a clamping body exemption with a safety device that can withstand higher torques.
Smart Images
Figure EP2024079557_08052025_PF_FP_ABST
Abstract
Description
[0001] Sprag freewheel with safety device
[0002] The invention relates to a sprag freewheel with an inner ring, an outer ring, a number of sprags which are accommodated in an annular gap between the inner ring and the outer ring, and with a securing device for the torque-resistant connection of the outer ring to an adjoining component.
[0003] Such sprag freewheels are generally used to selectively transmit torque from one component to another in only one direction. If a first component is connected to the outer ring of the freewheel and a second component is connected to the inner ring, the first component can rotate relative to the second component in one direction around the axis of the inner ring. If, however, a torque acts on the first component in the opposite direction, the freewheel locks, preventing rotation of that component.
[0004] Generally, the freewheel is a purchased part that is only connected to the first and second components during assembly. The locking effect of the freewheel only comes into effect if a sufficiently strong connection can be established between the first component and the outer ring of the freewheel.
[0005] Typically, the outer ring of the freewheel is in the form of a cylindrical sleeve that can be press-fitted into a corresponding bore in the first component. However, due to thermal expansion, the press-fit connection may no longer be able to withstand higher torque, meaning that rotation of the first component in the locking direction can no longer be reliably prevented.
[0006] WO 2020 / 120661 A1 describes a sprag freewheel of the type mentioned above, in which a locking device on the outer ring ensures that the connection between the outer ring and the adjoining component can withstand a higher torque. The locking device can be formed, for example, by the outer ring having a radially projecting flange at one end, on which wrench flats or other locking contours are formed that can be brought into engagement with complementary contours on the component. During the manufacture of the sprag freewheel, the radial flange must then be formed on the outer ring in a first step, and the outer edge of this flange must be machined in a second step.
[0007] The object of the invention is to create a sprag freewheel with a safety device that is easier to manufacture.
[0008] This object is achieved according to the invention in that the safety device is formed by a ring of projections formed in one piece with the outer ring, which project axially from an end face of the outer ring and are distributed around the circumference of the outer ring. A precursor for the outer ring with the safety device can then be easily produced in a deep-drawing and punching process. The result is a cylindrical sleeve which has a base at one end from which an inner part is punched out, leaving projections which initially point radially inwards from the edge of the sleeve. In a further forming step, these projections can then be bent in the axial direction. The number and dimensions of the projections can be adapted within a wide range to the limit torque which the safety device is intended to withstand.
[0009] Advantageous embodiments of the invention are specified in the subclaims.
[0010] In one embodiment, the outer ring can have a radially inwardly facing collar in the spaces between the individual projections, which increases the deformation stiffness of the outer ring.
[0011] In the following, an embodiment example is explained in more detail using the drawing.
[0012] They show:
[0013] Fig. 1 shows an outer ring of a sprag freewheel according to the invention in a side view;
[0014] Fig. 2 shows the outer ring according to Fig. 1 in an end view from the direction of arrows II-II;
[0015] Fig. 3 shows a section through the sprag freewheel together with a part of a lever-like component that is torque-rigidly connected to the outer ring of the freewheel; and Fig. 4 shows a view of the lever-like component alone.
[0016] Fig. 1 shows a side view of a substantially cylindrical outer ring 10 of a sprag freewheel. The outer ring has a radially outwardly projecting flange 12 at one end and a securing device 14 at the opposite end, which serves to establish a torque-resistant connection between the outer ring 10 and a component 16 shown in Figs. 3 and 4. In this example, the securing device 14 is formed by eight tab-like projections 18 that project in the axial direction of the outer ring 10 and are distributed at equal angular intervals around the circumference of the outer ring.
[0017] At the end that forms the securing device 14, the edge of the sleeve forming the outer ring 10 is slightly rounded. The end view in Fig. 2 shows that the peripheral wall of the sleeve transitions beyond this rounding into a radially inward-facing collar 20, which, however, is interrupted by a gap 22 at the positions of the projections 18.
[0018] The outer ring 10 with the shape shown in Figs. 1 and 2 can be manufactured, for example, by a combined stamping and deep-drawing process, in which a cylindrical cup is formed by deep drawing, from whose base the inner part is then punched out, leaving only the individual segments of the collar 20 and the tabs that later form the projections 18, but initially also point radially inward. In a further forming step, the projections 18 are then bent into the axial orientation.
[0019] Fig. 3 shows the lever-like component 16 and—in a sectional view—a complete sprag clutch 24, which comprises the outer ring 10, an inner ring 26, and sprags (clamping rollers) 28. The inner ring 26 has keyways 30 on its inner circumferential edge, with which it can be keyed onto a shaft (not shown).
[0020] In the example shown, the inner circumferential surface of the outer ring 10 forms a clamping contour 32 for the clamping bodies 28. This clamping contour can be efficiently produced using the aforementioned deep-drawing process. The securing device 14 formed by the projections 18 is not visible in Fig. 3, but parts of the collar 20 are visible.
[0021] Fig. 4 shows that component 16 has a ring of circular-arc-shaped slots 34, the positions and outlines of which correspond to the positions and contours of the projections 18 in Fig. 2. Component 16 can therefore be attached flat to outer ring 10 by welding or other means, so that the projections 18 engage in the slots 34 and thus create a particularly torque-resistant connection between outer ring 10 and component 16. At the same time, the slots 34 and the securing device 14 allow simple and precise centering of the sprag freewheel. The slots 34 can be produced by laser cutting or, for example, in the case of components 16 made of aluminum, also by punching.
Claims
PATENT CLAIMS 1. Sprag freewheel (24) with an inner ring (26), an outer ring (10), a number of sprags (28) which are accommodated in an annular gap between the inner ring (26) and the outer ring (10), and with a securing device (14) for the torque-resistant connection of the outer ring (10) to an adjoining component (16), characterized in that the securing device (14) is formed by a ring of projections (18) formed in one piece with the outer ring (10), which project axially from an end face of the outer ring and are distributed over the circumference of the outer ring.
2. Sprag freewheel (24) according to claim 1, wherein the outer ring (10) has, at the end at which the securing device (14) is located, a radially inwardly projecting collar (20) which is interrupted by gaps (22) in which the projections (18) are located.
3. Clamping body freewheel (24) according to claim 1 or 2, wherein the outer ring (10) is a deep-drawn part, the projections (18) of which are bent after deep-drawing from an initially radially inwardly pointing orientation into an axial orientation.
4. Clamping body freewheel (24) according to claim 3, wherein a clamping contour (32) is formed on the inner surface of the outer ring (10).