Toothed belt comprising teeth having asymmetric contours

Abstract

A toothed belt includes an asymmetric tooth profile. The teeth of the toothed belt include a vertical section on the front side of the teeth that allows the teeth to carry an increased load. This in turn helps to prevent tooth skipping. A sprocket configured to smoothly enter and exit the toothed belt is also described, and the toothed belt and the sprocket may form part of a belt drive system.

Description

[0001] Related Applications

[0002] This application claims priority to U.S. Provisional Application No. 63 / 396,599, filed on August 10, 2022, entitled “TOOTHED BELTS INCLUDING TEETHWITH ASYMMETRIC PROFILES,” the entire disclosure of which is incorporated herein by reference for all purposes. Background Art

[0003] When an impact load is applied to a drive system consisting of a toothed belt and a sprocket, the teeth of the belt may jump over the sprocket teeth into the next groove in the belt's rotational direction. This situation is often referred to as "tooth jump". Tooth jump may cause problems in the operation of the drive system, as well as belt delamination, tooth wear, material fatigue, and ultimately belt failure.

[0004] Another problem that can occur with drive systems consisting of toothed belts and sprockets is poor meshing between the belt profile and the sprocket profile. Poor meshing can generate noise. Since noise reduction is one of the main advantages of belt drives over chain drives, noise generated by poor meshing in belt drive systems is highly undesirable.

[0005] A variety of design strategies for toothed belt profiles and pulley or sprocket profiles have been proposed. A representative technology is U.S. Publication No. 2009 / 0156341, which discloses a belt and sprocket system, the belt having a tensioning cord disposed within a belt body, teeth protruding from the belt body, the teeth having a profile with at least two unequal radii, the at least two unequal radii being sequentially connected and disposed between the tooth tip and the tooth root, the sprocket having a groove for receiving the tooth, the groove profile including at least one generally linear portion disposed between the at least two unequal radii, the tooth tip engaging a predetermined portion of the sprocket groove so that the tensioning cord is supported such that the tensioning cord has a generally arcuate form between the tooth roots. However, this design, as well as other designs, generally focuses on the engagement of the tooth tip with the sprocket, rather than the engagement of the front side of the belt tooth where the force is applied.

[0006] Therefore, there is a need for improved belt drive systems in which the problems associated with tooth jump and noise generation are addressed. Summary of the invention

[0007] This summary is provided to introduce in simplified form a selection of some concepts that will be further described below in the detailed description. This summary and the foregoing background technology are not intended to identify the key features or essential features of the claimed subject matter. In addition, this summary is not intended to be used to help determine the scope of the claimed subject matter.

[0008] In some embodiments, a toothed belt is described, the toothed belt generally comprising a belt body portion and a plurality of teeth spaced around the entire inner periphery of the belt and extending from the belt body portion in a radially inward direction. Each tooth of the toothed belt generally has a height extending from an inter-tooth platform of the tooth to a tooth tip, and a cross-sectional profile of each tooth comprises a vertical segment at a front side of the tooth, the vertical segment being oriented substantially perpendicular to the belt body portion when the toothed belt is in a rack state. The length of the vertical segment of each tooth is less than the height of the tooth.

[0009] In some embodiments, a belt drive system is described, the belt drive system generally comprising a toothed belt as described in the previous paragraph, and a sprocket configured to engage with and rotate the toothed belt. The sprocket comprises a plurality of teeth, wherein the shape of each tooth of the sprocket and the spacing between adjacent teeth in the sprocket are configured to smoothly engage with the teeth of the toothed belt.

[0010] These and other aspects of the technology described herein will become apparent after considering the detailed description and drawings herein. However, it should be understood that the scope of the subject matter claimed should be determined by the issued claims, rather than by whether a given subject matter solves any or all of the problems mentioned in the background technology or includes any features or aspects listed in the summary of the invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Non-limiting and non-exhaustive embodiments of the disclosed technology, including preferred embodiments, are described with reference to the following figures, wherein like reference numerals refer to like parts throughout the various views unless otherwise specified.

[0012] Figure 1 A three-dimensional diagram of a toothed belt.

[0013] Figure 2A is a side plan view of a cross section of a toothed belt showing the profile of teeth constructed in accordance with various embodiments described herein.

[0014] Figure 2B for Figure 2A A cross-sectional view of a tooth showing the profile of a tooth constructed according to various embodiments described herein. DETAILED DESCRIPTION

[0015] Embodiments are described more fully below with reference to the accompanying drawings, which form a part of the embodiments and show specific exemplary embodiments by way of example. These embodiments are disclosed in sufficient detail to enable those skilled in the art to practice the invention. However, the embodiments may be implemented in many different forms and should not be construed as being limited to the embodiments set forth herein. Therefore, the following detailed description should not be considered restrictive.

[0016] Figure 1 A conventional belt 100 is shown, the belt 100 having a belt body portion 102 formed of a flexible material, the belt body portion 102 having a back side 104 and a front side 106, wherein a plurality of load-bearing cords 108 are provided within the body portion 102, the particular cords 108 being bundled in three bundles, but in other embodiments, the cords 108 may be a single cord or bundled in other ways. The cords 108 may be, for example, carbon cords, polymer cords (e.g., polyester, aramid), fiberglass cords, etc. A plurality of teeth 110 are defined in the front side 106; although in Figure 1 The teeth are generally depicted as being trapezoidal in shape for purposes of illustration only, but it should be understood that the belt 100 may have an asymmetrical tooth shape according to various embodiments described herein. There are inter-tooth lands 121 between adjacent teeth 110 .

[0017] Each individual tooth 110 extends perpendicular to the longitudinal length of the belt 100 so that the plurality of teeth 110 extend along or around the length of the belt 100. In use, the teeth 110 on the positive side 106 contact a drive mechanism such as a gear or sprocket. Figure 1 Although not visible in FIG, belt 100 is an endless belt in the form of a loop with no beginning and no end. Figure 1 , the toothed belt 100 is shown in a rack state, which means that the belt 100 is laid flat, rather than having any degree of curvature. In this rack state, the belt 100 includes a longitudinal axis 131.

[0018] about Figure 2A , shows a toothed belt 200 constructed according to various embodiments described herein. The toothed belt 200 generally includes a belt body portion 202 and a plurality of teeth 210 extending from the body portion 202 in a radially inward direction, for example, when the belt is annular, such as when the belt is an endless belt. The body portion can have a thickness t, which is generally not limited and can vary based on the specific application of the belt 200. In Figure 2A , the toothed belt 200 is shown in the rack state; in this rack state, the belt 200 comprises a longitudinal axis 231 .

[0019] Although Figure 2AA single tooth 210 is shown, but it should be understood that a plurality of teeth 210 are arranged around the entire inner peripheral portion of the main body portion 202 and are spaced apart from each other at uniform intervals, wherein inter-tooth platforms 221 exist between adjacent teeth 210, such as Figure 1 It should also be appreciated that each tooth 210 included in the belt 200 is substantially identical in shape and size (details of which will be discussed in greater detail below).

[0020] like Figure 2A As further shown in FIG. 1 , each tooth 210 has a height h extending from an inter-tooth platform 221 adjacent to the tooth 210 to a tooth tip 222 of the tooth; the maximum height h may not be at the center of the tooth 210. Based on the direction of travel of the belt 200, each tooth 210 further includes a front side 223 and a rear side 224; Figure 2A An arrow 230 is included to indicate the direction of travel of the belt 200. The front side 223 is the side of the tooth 210 to which force is applied, typically via the teeth of a sprocket pushing against the front side 223, to move the toothed belt 200 in the direction indicated by the arrow 230; the rear side 224 is the side of the tooth 210 opposite the front side 223. As discussed in more detail below, the rear side 224 of each tooth 210 is typically shaped to provide smooth meshing between the sprocket and the toothed belt 200, that is, to provide smooth entry and exit of the sprocket teeth in the spaces between the teeth 210 of the toothed belt 200.

[0021] refer to Figure 2B , showing a cross-sectional profile of a tooth 210. The cross-sectional profile of the tooth 210 includes a vertical segment 225 between the inter-tooth platform 221 and the tooth tip 222 of the tooth 210 on the front side 223 of the tooth 210. The vertical segment 225 is perpendicular (or orthogonal) to the direction of the force applied to the tooth 210 by the sprocket teeth. The vertical segment 225 increases the load that the tooth 210 can carry; this allows greater forces to be applied to the belt without the belt jumping on the teeth of the sprocket.

[0022] The vertical section 225 is located at Figure 2B225 and point P3, where point P2 marks the radially outer end of the vertical segment 225 and point P3 marks the radially inner end of the vertical segment 225 based on the belt being in an annular configuration. When the belt 200 is in a rack (i.e., flat) state, the vertical segment 225 forms an angle 226 with the longitudinal axis 231 of the main body portion 202 when extending to intersect the longitudinal axis 231. In order to provide the desired vertical orientation of the vertical segment 225, the angle 226 is generally 90°. In other words, the vertical segment 225 is generally oriented perpendicular to the longitudinal axis 231 and the belt main body portion 202. In some embodiments, the angle 226 need not be exactly 90°; for example, in some embodiments, the angle 226 is in the range of 86° to 110°, in which case the vertical segment 225 still desirably increases the amount of force that can be applied to the tooth 210 without causing tooth jump.

[0023] The length of the vertical segment 225 (measured between P2 and P3) is generally less than the height h of the tooth 210. The length of the vertical segment 225 is generally not limited as long as the length of the vertical segment 225 is less than the height h of the tooth 210. In some embodiments, the length of the vertical segment 225 is 10% to 90% of the height h of the tooth 210. In some embodiments, the length of the vertical segment 225 is 30% to 60% of the height h of the tooth 210.

[0024] The vertical section 225 having a length less than the height h of the tooth 210 allows the front side 223 of the tooth 210 to have a first curved portion 227 between the inter-tooth platform 221 and the vertical section 225 or between the inter-tooth platform 221 and the radially outer end P2; it also allows a second curved portion 228 between the vertical section 225 and the tooth tip 222 of the tooth 210 or between the radially inner end P3 and the tooth tip 222 of the tooth 210. The first curved portion 227 can generally be located at Figure 2B , and the second curved portion 228 may generally extend from point P3 to a point intermediate between points P4 and P5. These curved portions 227, 228 provide a gradual transition near the junction of the tooth 210 and the belt body portion 202 and near the tooth tip 222 of the tooth 210. The first curved portion 227 and the second curved portion 228 may make the manufacturing of the tooth profile easier and may also contribute to better meshing between the toothed belt and the sprocket.

[0025] At the rear side 224 of the tooth 210, a third curved portion 229 may be provided, which generally extends downward from the tooth tip 222 of the tooth 210 to the junction of the rear side 223 of the tooth 210 and the belt body portion. The third curved portion 229 may extend downward from a point intermediate between points P4 and P5 to point P8. Thus, the third curved portion 229 may include a convex curved portion and a concave curved portion. In some embodiments, the third curved portion 229 has no or substantially no vertical segments, so that the rear side 224 of the tooth 210 does not include a vertically oriented segment (or, a segment perpendicular to or substantially perpendicular to the belt body portion). By providing the rear side of the tooth 210 in this manner, the tooth profile disclosed herein allows for smooth entry and exit from the sprocket, which improves meshing and reduces noise.

[0026] Tables 1 and 2 below provide exemplary, non-limiting data for the locations of points P1 to P8 and the radius of curvature R1 to R6 of the segments between adjacent points. The data is merely exemplary, and the values ​​of points P1 to P8 and R1 to R6 can be easily adjusted. For the given data, the only constant is that there is no radius of curvature between points P2 and P3, because the segment between points P2 and P3 is a vertical segment 225.

[0027] Table 1 and Table 2 use Figure 2B , where the X-axis is the base of the tooth 210 (e.g., at the inter-tooth platform 221), and the Y-axis is the center of the tooth 210, substantially equally between the base of the front side 223 and the base of the rear side 224. The Y-axis may or may not be the location of the tooth tip 222; that is, the tooth tip 222 may be offset from the center or Y-axis of the tooth 210. The data in the table is normalized without any associated units.

[0028] The data in Table 2 indicates that the X position between points P2 and P3 does not change, thus indicating a vertical orientation of the vertical segment 225. However, in embodiments where the vertical segment is substantially vertical (e.g., oriented at an angle between 86° and 110°), the X position between points P2 and P3 may change slightly. Regardless, the segment still has no radius of curvature because the vertical segment 225 is a straight segment.

[0029] Table 1

[0030]

[0031] Table 2

[0032]

[0033]

[0034] As from Figure 2A and Figure 2BAs can be seen in Tables 1 and 2, in addition to having a vertical segment 225 on the rear side 223, the tooth 210 and its variations according to the present disclosure are not symmetrical about the Y axis of the tooth, and the rear side 223 has a different profile than the front side 224. In some embodiments, the front side 224 can include straight segments, even though the overall profile of the front side 224 is arcuate (concave, convex, or a combination thereof). The tooth tip 222 can be offset to the rear side 223 or the front side 224.

[0035] As previously mentioned, embodiments of the toothed belts described herein may be used with a sprocket for engaging with and rotating the toothed belt. The combination of the toothed belt and sprocket may form a belt drive system. The sprocket typically includes teeth and grooves that are sized and shaped to provide a dynamic fit between the toothed belt and the sprocket that allows the sprocket teeth to smoothly enter and exit the toothed belt. More specifically, the shape of the sprocket teeth, the shape of the grooves between the sprocket teeth, and the spacing between the sprocket teeth are designed to accommodate at least a vertical segment portion of the leading edge of the teeth of the toothed belt. This vertical segment may require the sprocket design to have a "scooped out" profile that mates with a vertical segment on the teeth of the toothed belt. By providing a sprocket design that is specifically configured to engage with a specific profile of the toothed belt (i.e., a vertical segment of the leading edge of the teeth of the toothed belt), the sprocket provides a smooth engagement with the teeth of the toothed belt, which may contribute to performance and noise reduction of the belt drive system.

[0036] Any suitable method can be used to manufacture the toothed belts described herein. In some embodiments, the toothed belts are manufactured using a molding process, including a slab build molding process. When a molding process is used, a mold is manufactured to form teeth with an asymmetric profile having vertical segments as described herein.

[0037] The materials of the toothed belts 100, 200 described herein are generally not limited, and the different components of the toothed belts can use any suitable materials. Typically, the base material for the belt body portion 102, 202 and the teeth 110, 210 is a polymer material, such as a natural or synthetic rubber material, but other suitable materials (e.g., polyurethane) can also be used. Various filling materials can also be included in the material of the belt body portion and / or the teeth to further increase the structural stability of the belt, and in other embodiments, the belt can be free of or substantially free of filling materials. Figure 1 and 2A The toothed belts 100, 200 shown in the drawings may also include additional features not shown in the drawings. For example, a cover layer may be provided on the outer surface of the teeth 110, 210, a backing layer may be provided on the radial outer surface of the belt body portion 102, 202, and / or a plurality of reinforcing fibers may be embedded in the belt body portion 102, 202.

[0038] The toothed belts described herein offer various advantages. Some of these advantages have been discussed previously, such as the ability to carry heavier loads and reduced noise. Additionally, the toothed belts described herein allow for greater hub loads than existing profiles. With the increased performance, the belt width can be reduced or the range of applications can be increased for the same specification compared to published tooth profiles. Additionally, consumers benefit from the designs described herein that have improved performance in terms of reduced noise and reduced tooth jump. High-end drive system performance can be applied to the mid-market at a lower cost.

[0039] In summary, it should be appreciated that specific embodiments of the present invention have been described for purposes of illustration, but that various modifications may be made without departing from the scope of the present invention. Accordingly, the present invention is not to be limited except as in the appended claims.

[0040] Although the technology has been described in language specific to certain structures and materials, it should be understood that the invention defined in the appended claims is not necessarily limited to the specific structures and materials described. Instead, specific aspects are described as forms of implementing the claimed invention. Because many embodiments of the invention can be practiced without departing from the spirit and scope of the invention, the invention resides in the claims appended hereto.

[0041] Unless otherwise specified, all numbers or expressions used in the specification (except for the claims), such as those expressing dimensions, physical properties, etc., should be understood to be modified by the term "approximately" in all cases. At least, and without attempting to limit the application of the equivalent principle of the claims, each numerical parameter modified by the term "approximately" quoted in the specification or claims should at least be interpreted according to the number of significant figures listed and by applying rounding methods. In addition, all ranges disclosed herein should be understood to include and support claims that list any and all subranges or any and all single values ​​contained therein. For example, the range of "1 to 10" set forth should be considered to include and support claims that list any and all subranges or single values ​​between a minimum value of 1 and a maximum value of 10 and / or include a minimum value of 1 and a maximum value of 10; that is, all subranges starting with a minimum value of 1 or greater and ending with a maximum value of 10 or less (e.g., 5.5 to 10, 2.34 to 3.56, etc.) or any value between 1 and 10 (e.g., 3, 5.8, 9.9994, etc.).

Claims

1. A toothed belt comprising: With main body part; as well as a plurality of teeth evenly spaced about an inner periphery of the toothed belt, each tooth extending from the belt body in a radially inward direction, and each tooth having a height extending from an inter-tooth platform to a tooth tip, wherein a cross-sectional profile of each tooth comprises: At the front side of the tooth, a vertical section is oriented substantially perpendicular to the longitudinal axis of the belt body portion when the toothed belt is in the rack state, the length of the vertical section being less than the height of the tooth.

2. The toothed belt according to claim 1, wherein when the toothed belt is in a rack state, the vertical section forms an angle with respect to the longitudinal axis of the belt body portion, the angle being 86° to 110°.

3. The toothed belt according to claim 2, wherein: When the toothed belt is in the rack state, the vertical section has an angle of 90° relative to the longitudinal axis of the belt body portion.

4. The toothed belt according to claim 1, wherein: The length of the vertical section is 10% to 90% of the height of the tooth.

5. The toothed belt according to claim 1, wherein: The length of the vertical section is 30% to 60% of the height of the tooth.

6. The toothed belt according to claim 1, wherein: The cross-sectional profile of each tooth further comprises: a first curved portion extending from the inter-tooth platform to the radially outer end of the vertical segment at the front side of the tooth; and At the front side of the tooth, a second curved portion extends from the radially inner end of the vertical section to the tooth tip of the tooth.

7. The toothed belt according to claim 1, wherein: The cross-sectional profile of each tooth further comprises: At the rear side of the tooth, a third curved portion extends from the tooth tip of the tooth to the inter-tooth platform, the third curved portion having substantially no vertical section.

8. The toothed belt according to claim 7, wherein: The third curved portion is configured to provide smooth engagement between the toothed belt and a corresponding sprocket.

9. The toothed belt according to claim 7, wherein: The third curved portion is configured to provide reduced noise during intermeshing of the toothed belt and a corresponding sprocket.

10. A belt drive system comprising: Toothed belt, comprising: with a main body portion; and a plurality of teeth evenly spaced about an inner periphery of the toothed belt, each tooth extending from the belt body in a radially inward direction, and each tooth having a height extending from an inter-tooth platform to a tooth tip, wherein a cross-sectional profile of each tooth comprises: a vertical section at the front side of the tooth oriented substantially perpendicular to the longitudinal axis of the belt body portion when the toothed belt is in the rack state, the length of the vertical section being less than the height of the tooth; and a sprocket configured to engage with and rotate the toothed belt, the sprocket comprising a plurality of teeth, wherein: The profile of each tooth of the sprocket and the spacing between adjacent teeth in the sprocket are configured to smoothly mesh with the teeth of the toothed belt.

11. The belt drive system of claim 10, wherein: The profile of each tooth of the sprocket and the spacing between adjacent teeth in the sprocket are specifically adjusted so that the sprocket accommodates the vertical segments of the teeth of the toothed belt.

12. The belt drive system of claim 11, wherein: When the toothed belt is in the rack state, the vertical segment forms an angle with respect to the longitudinal axis of the belt body portion, the angle being in the range of 86° to 110°.

13. The belt drive system of claim 12, wherein: When the toothed belt is in the rack state, the vertical section has an angle of 90° relative to the longitudinal axis of the belt body portion.

14. The belt drive system of claim 11, wherein: The length of the vertical section is 10% to 90% of the height of the tooth.

15. The belt drive system of claim 11, wherein: The length of the vertical section is 30% to 60% of the height of the tooth.

16. A toothed belt comprising: a belt body portion having a longitudinal axis; as well as a plurality of teeth evenly spaced about an inner periphery of the toothed belt, each tooth having a front side and a rear side and a height extending from an inter-tooth platform to a tooth tip, wherein: The cross-sectional profile of each tooth is asymmetric about a Y-axis which is equally located between the inter-tooth platforms on the front side and the inter-tooth platforms on the rear side, and At the front side of the tooth, when the toothed belt is in the rack state, the cross section has a vertical section oriented substantially perpendicular to the belt body portion, the length of the vertical section being less than the height of the tooth.

17. The toothed belt according to claim 16, wherein: The length of the vertical section is 10% to 90% of the height of the tooth.

18. The toothed belt according to claim 17, wherein: The length of the vertical section is 30% to 60% of the height of the tooth.

19. The toothed belt according to claim 16, wherein when the toothed belt is in a rack state, the vertical section forms an angle with respect to the belt main body, the angle being 86° to 110°.

20. The toothed belt according to claim 19, wherein: When the toothed belt is in the rack state, the vertical section has an angle of 90° relative to the longitudinal axis of the belt body portion.

Images