Freewheel element

Abstract

The present invention relates to a freewheel element (4) comprising a plurality of clamping bodies (10) and a cage (5), wherein the cage (5) has axially extending webs (8) distributed at equal intervals along the circumference of the cage (5) and pockets, each of which receives one of the clamping bodies (10), the webs (8) have higher elasticity than the clamping bodies (10), and the webs (8) are formed to have a U-shaped cross-section when viewed in the axial direction.

Description

Technical Field

[0001] The present invention relates to a freewheel element.

Background Art

[0002] Freewheel elements are used, for example, in overrunning clutches that transmit or support torque by force coupling in one direction and allow free rotation in the opposite direction. In this case, in a clamping freewheel (sprag one-way clutch), within the clamping gap, the clamping body (sprag) is in a so-called clamping position or clamping position when the clamping body transmits torque by force coupling, that is, by frictional coupling, and is in a so-called free rotation position or free rotation position when the clamping body allows free rotation.

[0003] Conventional clamping freewheels, in addition to the clamping body, have, inter alia, a clamping body cage (hereinafter also simply referred to as the cage) in which the clamping body is received, and a metal spring that uses spring force to hold the clamping body in a predetermined position (the so-called spring pressing of the clamping body). Therefore, this type of clamping freewheel of a known structural form consists of at least three different components and accordingly involves high manufacturing costs. In contrast, the clamping freewheel described in the following Patent Document 1 (EP 2 660 488 A1) can omit the metal spring. There, spring pressing is performed by the web of the elastically configured cage.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, a drawback of the above-mentioned Patent Document 1 is that the spring deflection achievable by the elastic web is relatively small. This results in high tolerance requirements for the elements of the clamping freewheel and for the components connected by the clamping freewheel. In addition, for example, eccentricity that occurs during the operation of the clamping freewheel changes the clamping gap, causing some clamping bodies to generate increased drag torque, while other clamping bodies are not sufficiently spring-pressed.

[0006] The object of the present invention is to provide an easily assembled freewheel element that can function over a relatively large tolerance range and even when eccentricity occurs within the clamping gap. [Means for solving the problem]

[0007] The aforementioned problem is solved by a freewheel element having the features of claim 1. Advantageous embodiments of the freewheel element are described in the lower claims.

[0008] The freewheel element according to the present invention comprises a plurality of clamping bodies and a cage. The cage has axially extending webs (elastic members) distributed at equal intervals along the circumference of the cage, and pockets in each web, each of which receives one of the clamping bodies. The webs have higher elasticity than the clamping bodies, and the webs are formed to have a U-shaped cross-section when viewed in the axial direction.

[0009] Because the elasticity of the webs of the clamping cage is higher than that of the clamping body, these webs act as spring elements. Therefore, such a structure eliminates the need for metal springs, resulting in a clamping freewheel that is particularly easy to assemble and manufacture. In this context, "higher elasticity" is understood to mean that the webs are manufactured from a material having higher elastic properties than the material from which the clamping body is manufactured. The clamping body is preferably manufactured from a metallic material, such as steel. Accordingly, the webs have greater elasticity than the metallic material.

[0010] The U-shaped cross-section of the web, viewed axially, increases the possible spring deflection. In other words, the web behaves similarly to a bent spring. This means that the positioning of the clamping body does not need to be very precise and is less susceptible to eccentricity of the clamping gap or dimensional inaccuracies of the connecting parts. Thus, the freewheel element is also suitable for thin-walled connecting parts.

[0011] Preferably, the opening of the U-shaped cross-section is oriented radially inward or outward. This orientation of the cross-section allows each lateral end region of each web to be in contact with the adjacent clamping body, and maximizes the spring action of the cross-sectional shape.

[0012] In one advantageous embodiment, the freewheel element further has at least one cage side plate (gauge board), and each web is connected to the cage side plate by a rotating spring bar. In other words, one rotating spring bar is disposed between each cage side plate and web. In this way, the web is twistable relative to the cage side plate; that is, the rotating spring bar acts like a torsion spring. This makes the freewheel element less susceptible to eccentricity of the clamping gap or dimensional inaccuracies of the connecting parts.

[0013] In this configuration, the connection point between the web and the rotary spring bar can be located at one end of the U-shaped cross-section. This allows the bending spring action of the web and the torsional spring action of the rotary spring bar to effectively overlap.

[0014] Advantageously, the clamping body is received within a pocket in a shape-engagement manner, particularly in the form of a snap-in or snap-in connection. This allows for easy assembly or disassembly of the freewheel element, on the one hand, and ensures reliable support of the clamping body during operation. Utilizing the elastic properties of the web, the clamping body pocket can be elastically expanded to allow the clamping body to snap into the pocket.

[0015] Generally, the clamping body has a first contact zone for contacting an adjacent first web and a second contact zone for contacting an adjacent second web. Preferably, the first and second contact zones differ from each other in their radial positions. In other words, one contact zone is located inward (i.e., closer to the central axis of the freewheel element) than the other contact zone. This makes it possible to apply torque to the clamping body, thereby influencing, for example, the spring pressure of the clamping body. The magnitude and direction of the torque can also be adjusted by the relative positions of the contact zones.

[0016] In a further advantageous embodiment, the first contact zone and / or the second contact zone are formed as surfaces corresponding to the lateral end regions of the U-shaped cross-section of the web. In other words, the contact zone of the clamping body has a curve or shape corresponding to the opposite image of the curve or shape of the web. Thus, a specially defined and reproducible contact between the web and the clamping body is possible.

[0017] In an advantageous embodiment, at least the web and the rotary spring bar are made of a polymer material, particularly of polyamide. Preferably, the polymer material contains a filler, particularly in the form of fibers and / or spheres. If reinforcing fibers are used, they are preferably oriented along the longitudinal direction of the U-shaped cross-section of the web.

[0018] Particularly, as a material of glass fiber reinforced polyamide, particularly preferably PA46GF15 (polyamide 46 having a 15% glass fiber portion) is suitable. Either only the web and / or the rotary spring bar or the entire clamping body cage can be made of the above material. By using the above material, particularly advantageous spring characteristics can be achieved.

[0019] Based on the embodiments in each figure of the drawings, the present invention will be further described.

Brief Description of the Drawings

[0020] [Figure 1] It is a figure showing a cross-sectional view of a clamping body freewheel provided with an inner ring, an outer ring, and a freewheel element disposed therebetween. [Figure 2] It is a figure showing a part of the cross-sectional view of the freewheel element of FIG. 1. [Figure 3] It is a figure showing a side view of the freewheel element of FIG. 1. [Figure 4] It is a figure showing a perspective view of the freewheel element of FIG. 1. [Figure 5] It is a figure showing a part from the perspective view of one cage of the freewheel element of FIG. 1. [Figure 6] It is a figure showing a part of the cross-sectional view of the freewheel element of FIG. 1.

Embodiments for Carrying Out the Invention

[0021] Figure 1 shows a cross-sectional view of a clamping body freewheel (sprag type one-way clutch) 1. The clamping body freewheel 1 has an inner ring 2 and an outer ring 3. The outer ring 3 is arranged coaxially with the inner ring 2. A gap called a so-called clamping gap is formed between the inner ring 2 and the outer ring 3. A freewheel element 4 is arranged in this gap. This freewheel element 4 will be described in detail in FIGS. 2 to 6.

[0022] The freewheel element 4 is substantially ring-shaped and has a cage 5 made of a fiber-reinforced polymer material (polyamide 46 having a 15% glass fiber portion). The cage 5 has a first cage side plate (cage board) 6 and a second cage side plate 7 offset in the axial direction. Between the first cage side plate 6 and the second cage side plate 7, axially extending webs (elastic members) 8 are arranged at equal intervals. For the sake of clarity of the drawing, not all elements existing in plurality in the figure are individually labeled with reference signs. That is, for example, in FIG. 1, only one web 8 is labeled. Those webs 8 are each connected to one of the cage side plates 6, 7 via one rotating spring bar 9. As elements, the first cage side plate 6, the second cage side plate 7, the web 8, and the rotating spring bar 9 together constitute the cage 5.

[0023] The space volume between each adjacent two webs 8 and the cage side plates 6, 7 constitutes one pocket for receiving one clamping body (sprag) 10. At this time, the connection between the clamping body 10 and the cage 5 is configured as a snap connection. The clamping body 10 is made of steel. Thereby, the cage 5 is made of a material having higher elasticity than the material of which the clamping body 10 is made.

[0024] The web 8 has a U-shaped cross-section when viewed in the axial direction. The opening of the U faces radially inward, i.e., in the direction of the central axis of the freewheel element. The curved portion of the U faces radially outward. Each of the lateral elements (legs) of the U contacts one of the clamping bodies 10 adjacent to each web 8. In other words, the clamping body 10 contacts an adjacent first web 8 in the first contact zone 11, and contacts an adjacent second web 8 in the second contact zone 12. The first contact zone 11 and the second contact zone 12 are different from each other in their radial positions. More precisely, the second contact zone 12 is located further inward than the first contact zone 11.

[0025] These webs 8 are connected to the first cage side plate 6 and the second cage side plate 7 via a single rotating spring bar 9 at one lateral end region of the U-shaped cross-section. Except for this connection, the webs 8 are configured to be self-supporting, meaning there are no further connections to the cage side plates 6 and 7. In this way, the webs 8 have high flexibility and bendability or torsional capability.

[0026] Referring to Figure 6, the function of the freewheel element 4 will be explained in detail. For the sake of ease of understanding, the clamping body 10a is shown in the clamping position, the clamping body 10b is in the intermediate position, and the clamping body 10c is shown in the free rotation position. In reality, all clamping bodies 10a, 10b, and 10c would be in the same position. In the clamping position, the clamping bodies 10a, 10b, and 10c form a frictional coupling connection with the inner ring 2 and the outer ring 3, thereby transmitting torque between the inner ring 2 and the outer ring 3. In contrast, in the free rotation position, the clamping bodies 10a, 10b, and 10c enable the relative rotational motion of the inner ring 2 with respect to the outer ring 3.

[0027] The clamping bodies 10a, 10b, and 10c, at their respective positions, contact the web 8 located between the first contact zone 11 and the second contact zone 12. These webs 8, based on their elasticity and U-shaped cross-section, act like bending springs. The webs 8 spring-elastically support the clamping bodies 10a, 10b, and 10c, changing their shape, i.e., widening or narrowing the U-shape. In addition, the rotating threaded rod 9 is twistable under torsional load. Overall, this ensures that the clamping bodies 10a, 10b, and 10c are reliably spring-pressed, reducing sliding resistance within the cage 5. This also ensures that the freewheel element 4 remains functional over a relatively large tolerance range and even during eccentricity occurring within the clamping gap, without the need for a metal spring for spring compression.

[0028] The application areas for the freewheel element 4 include, in particular, mounting situations where thin-walled connecting parts are present, such as freewheels in two-wheeled vehicles (bicycles, e-bikes, etc.).

[0029] Cage 5 is manufactured from glass fiber reinforced polyamide, and in this process, the appropriate injection point (gate) during injection molding ensures that the reinforcing fibers are oriented longitudinally across the U-shaped cross-section of the web. To achieve the most uniform material distribution possible, as many, or even all, of the webs should be bonded to the injection molding tool. In this regard, a central injection point in the web 8 was found to be advantageous. [Explanation of Symbols]

[0030] 1. Clamping body freewheel 2. Inner ring 3. Outer ring 4. Freewheel element 5 cages 6. First cage side panel 7. Second cage side panel 8 Web 9. Rotating spring bar 10 Clamping body 10a Clamping body 10b Clamping body 10c clamping body 11. First contact zone 12. Second contact zone

Claims

1. A freewheel element (4) comprising a plurality of clamping bodies (10) and a cage (5), The cage (5) has axially extending webs (8) distributed at equal intervals along the circumference of the cage (5), and pockets in each of which one of the clamping bodies (10) is received. The web (8) has higher elasticity than the clamping body (10), and The web (8) is formed to have a U-shaped cross-section when viewed in the axial direction. A freewheel element (4) characterized by the following.

2. The opening of the U-shaped cross-section is oriented radially inward or outward. The freewheel element (4) according to claim 1, characterized by the above.

3. Furthermore, it has at least one cage side plate (6, 7), and each web (8) is connected to the cage side plate (6, 7) by a rotating spring bar (9), A freewheel element (4) according to claim 1 or 2, characterized by the above.

4. The rotating spring bar (9) is connected to the web (8) at one end region of the U-shaped cross-section. The freewheel element (4) according to claim 3, characterized by the above.

5. The fastening body (10) is of the shape-engagement type, and is particularly received in the form of a snap connection or a snap connection within the pocket. A freewheel element (4) according to any one of claims 1 to 4, characterized by the above.

6. Each clamping body (10) has a first contact zone (11) for contacting an adjacent first web (8) and a second contact zone (12) for contacting an adjacent second web (8). A freewheel element (4) according to any one of claims 1 to 5, characterized by the above.

7. The first contact zone (11) and the second contact zone (12) are different from each other in their radial positions. The freewheel element (4) according to claim 6, characterized by the above.

8. The cage (5) is made of a polymer material, particularly polyamide, and the clamping body (10) is made of steel. A freewheel element (4) according to any one of claims 1 to 7, characterized by the above.

9. At least the web (8) is made of glass fiber reinforced polyamide, and in particular of PA46GF15. A freewheel element (4) according to any one of claims 1 to 8, characterized by the above.

10. The reinforcing fibers are oriented along the longitudinal direction of the U-shaped cross-section of the web (8). The freewheel element (4) according to claim 9, characterized by the above.

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