FREEWHEEL ELEMENT

Description

[0001] The invention relates to a freewheel element.

[0002] Freewheel elements are used, for example, in directional clutches that transmit or support torque in one direction through frictional engagement and allow freewheeling in the opposite direction. In sprag clutches, the sprags are in the so-called clamping position when they transmit torque forcefully, i.e., frictionally, and in the so-called freewheeling position when they allow freewheeling.

[0003] In addition to the sprags, conventional sprag freewheels also feature a cage in which the sprags are accommodated in pockets. EP 2 660 488 A1 shows such a sprag freewheel. The disadvantage of such sprag freewheels is that an additional bearing is required, since a conventional freewheel lacks bearing properties and therefore no load capacity.

[0004] DE 12 64 886 B discloses a freewheel element with a cage and an identical number of clamping elements and rolling elements. Both the clamping elements and the rolling elements are accommodated in pockets of the cage. The cage has a higher elasticity in the region of its pockets than the clamping elements and the rolling elements. DE 10 2006 038201 A1, US 3 006 447 A, US 5 664 653 A and DE 12 67 039 B describe further freewheel elements or bearings with a cage, clamping elements and rolling elements. US 5 676 226 A describes a freewheel element with an outer cage, an inner cage and an annular band spring arranged between the outer cage and the inner cage. The clamping elements and rolling elements extend through pockets of the inner cage and the outer cage and are held in position by tabs of the band spring.

[0005] The object of the present invention is to provide a freewheel element with integrated load capacity.

[0006] This object is achieved by a freewheel element having the features of claim 1. Advantageous embodiments of the freewheel are described in the subclaims.

[0007] The freewheel element according to the invention comprises a cage, a plurality of clamping elements, and a plurality of rolling elements. Each of the clamping elements is accommodated in a respective clamping element pocket formed in the cage. Each of the rolling elements is accommodated in a respective rolling element pocket formed in the cage. The cage has a higher elasticity than the clamping elements and the rolling elements.

[0008] By providing rolling elements, the load-bearing capacity can be integrated into the freewheel element. Furthermore, the cage acts as a spring element due to its greater elasticity compared to the clamping elements and rolling elements. This eliminates the need for metallic springs as spring elements. Furthermore, by selecting a cage material with a specific elasticity, it is possible to adjust the spring behavior of the clamping elements and / or the positional stability of the rolling elements over a wide range.

[0009] The clamping elements and the rolling elements are preferably made of a metallic material, in particular a steel material. Accordingly, the cage then exhibits an elasticity that is greater than that of metallic materials. However, rolling elements made of a ceramic material, for example, can also be used. In this case, the cage exhibits an elasticity that is greater than that of the metallic and ceramic materials used.

[0010] Preferably, the rolling element pockets—and thus also the rolling elements accommodated in these rolling element pockets—are distributed equidistantly around the circumference of the cage. This allows for uniform support along the circumference and a correspondingly uniform increase in the load capacity of the freewheel.

[0011] Providing an odd number of rolling element pockets along the circumference of the cage has proven advantageous. It is particularly advantageous to provide three, five, or seven equally spaced rolling element pockets. The larger the number of rolling elements, the greater the load capacity, but the freewheeling nature of the element suffers.

[0012] According to the invention, the rolling elements are accommodated in the rolling element pockets in a form-fitting manner, namely in the form of a locking or snap-in connection. This allows for easy assembly and disassembly of the rolling elements, while also ensuring secure mounting of the rolling elements. Utilizing the elastic properties of the cage material, the rolling element pocket can be elastically expanded to engage or snap the rolling element into the pocket.

[0013] According to the invention, the cage consists of a polymer material, in particular a polyamide. The polymer material preferably contains fillers, in particular in the form of fibers and / or spheres. Glass fiber-reinforced polyamide, particularly preferably PA 66 GF 25 (polyamide 66 with 25% glass fiber content), is particularly suitable as a material for the cage. Either just the cage areas around the rolling element pockets and / or the clamping element pockets or the entire cage can be made of the above-mentioned materials. By using the above-mentioned materials, a particularly advantageous spring behavior of the cage can be achieved. Furthermore, it is possible to adapt the elasticity and spring behavior of the cage by selecting the material and / or the mixing ratio of polymer base material to filler.

[0014] The invention is further explained using an exemplary embodiment in the drawing figures. They show: Fig. 1 a perspective view of a freewheel element; Fig. 2 a front view of the freewheel element from Fig. 1 ; Fig. 3 a side view of the freewheel element from Fig. 2 ; Fig. 4 a sectional view along the section plane AA from Fig. 3 ; Fig. 5that in Fig. 4 Freewheel element shown in an exemplary installation situation.

[0015] The freewheel element 1 shown in the figures is essentially annular and has a cage 10 made of a polymer material (e.g., polyamide 66 with 25% glass fiber content). A plurality of clamping element pockets 11 and a total of three rolling element pockets 12 are formed in the cage 10. For reasons of clarity, not all elements that are present multiple times are provided with a separate reference numeral in the figures. For example, in Fig. 4only one clamping body pocket 11 is provided with a reference number. The clamping body pockets 11 and the rolling body pockets 12 represent recesses or holes in the cage 10. In other words, the cage 10 has axially extending first and second webs 13 and 14, respectively, as well as annular end flanges 15, 16. The space between each two adjacent webs 13, 14 and the two end flanges 15, 16 forms a clamping body pocket 11 or a rolling body pocket 12, respectively. The webs 13 are each essentially cuboid-shaped and have a convex cross-section in the axial direction of the freewheel element 1. A plurality of clamping body pockets 11 are arranged between each two rolling body pockets 12 in the circumferential direction of the freewheel element.

[0016] Each of the clamping body pockets 11 accommodates a clamping body 20. The connection between the clamping body 20 and the cage 10 is designed as a snap connection. The clamping bodies 20 are made of a steel material.

[0017] Each of the rolling element pockets 12 accommodates a rolling element 30, wherein the rolling element 30 is designed as a cylindrical roller and made of a steel material. The connection between the rolling element 30 and the cage 10 is also designed as a snap connection. The rolling element pocket 12 is designed in such a way that it surrounds or encloses the rolling elements 30 from two sides (overlap), so that the roller-shaped rolling element 30 is held in the cage 10. At the same time, the overlap is chosen to be so small that, by utilizing the elastic properties of the cage material, it can be elastically expanded with simple manual assembly force in order to click / snap the rolling element 30 into the rolling element pocket 12.

[0018] The rolling element pockets 12 are wider in the circumferential direction than the clamping element pockets 11. In other words, the first webs 13 have a smaller distance from each other than the second webs 14 from each other.

[0019] The elasticity of the cage 10 - in particular the elasticity of the webs 13, 14 - is higher than the elasticity of the clamping bodies 20 and the rolling elements 30. This higher elasticity of the webs 13, 14 is achieved in particular by the fact that the cage 10 (or at least the webs 13, 14) is made of a material that has a lower modulus of elasticity than the materials from which the clamping bodies 20 and the rolling elements 30 are made.

[0020] Fig. 5shows an exemplary installation situation of the freewheel element 1 in a gap 40 between an inner first (solid) cylindrical component 50 and an outer second hollow cylindrical component 60. The dimensions and shape of the components 50 and 60 are to be regarded as purely illustrative. The first component 50 is arranged coaxially to the second component 60. The freewheel element 1 is arranged within this gap 40. In a clamping position, the clamping bodies 20 form a frictional connection with the first component 50 and the second component 60. In a freewheeling position, however, the clamping bodies 20 allow a rotational movement of the first component 50 relative to the second component 60. Each of the webs 13 has a spring surface. This spring surface is contacted by the adjacent clamping body 20 in the freewheeling position.More precisely, in the freewheeling position, a surface contact or overlap occurs between the spring surface of the web 13 and the adjacent clamping body 20. In the clamping position, however, the spring surface of the web 13 is not contacted by the clamping body 20.

[0021] The rolling elements 30 are in contact with the first component 50 and the second component 60 both in the clamping position and in the freewheeling position and enable a rolling bearing of the two components 50 and 60. In this way, the freewheel element 1 has a high load capacity and can simultaneously serve as a rotational direction-dependent coupling.

[0022] The freewheel element 1 shown in the figures thus comprises a cage 10, a plurality of clamping elements 20, and several rolling elements 30. The clamping elements 20 and the rolling elements 30 are accommodated in the clamping element pocket 11 and the rolling bearing pocket 12 by means of locking or snap-in connections. The cage 10 has a higher elasticity than the clamping elements 20 and the rolling elements 30. The total of three rolling element pockets 12 are distributed equidistantly around the circumference of the cage 10. LIST OF REFERENCE SYMBOLS

[0023] 1Freewheel element 10Cage 11Sprag pocket 12Rolling element pocket 13First web 14Second web 15First end flange 16Second end flange 20Sprag 30Rolling element 40Gap 50Cylindrical component 60Hollow cylindrical component

Claims

1. Freewheeling element (1) having: - a cage (10) made of a polymer material, - a plurality of sprags (20), wherein each of the sprags (20) is accommodated in a form-fitting manner in a respective sprag pocket (11) formed in the cage (10), and - a plurality of rolling bodies (30), wherein each of the rolling bodies (30) is accommodated in a form-fitting manner in a respective rolling-body pocket (12) formed in the cage (10), wherein the cage (10) has a higher level of elasticity than the sprags (20) and the rolling bodies (30), characterized in that: - a plurality of sprag pockets (11) are formed, in each case between two adjacent rolling-body pockets (12), along the circumference of the cage (10), - the rolling bodies (30) are accommodated in the rolling-body pockets (12) in the manner of a latching or snap-fit connection, and - the sprags (20) are accommodated in the sprag pockets (11) in the manner of a latching or snap-fit connection.

2. Freewheeling element according to Claim 1, wherein the rolling-body pockets (12) are distributed in an equidistant manner along the circumference of the cage (10).

3. Freewheeling element according to Claim 1 or 2, having an odd number of rolling-body pockets (12).

4. Freewheeling element according to Claim 3, wherein exactly three, five or seven rolling-body pockets (12) are formed.

5. Freewheeling element according to any one of the preceding claims, wherein the cage (10) consists of a polyamide.

6. Freewheeling element according to any one of the preceding claims, wherein the polymer material contains fillers, in particular fibres and / or balls.

7. Freewheeling element according to any one of the preceding claims, wherein the cage (10) consists of a glass-fibre-reinforced polyamide, in particular of PA 66 GF 25.