Cage mechanism, overrunning clutch, and electric power assist system

Abstract

The present invention relates to the technical field of clutches, and discloses a cage mechanism, an overrunning clutch, and an electric power steering system. The overrunning clutch includes an inner sprag, the cage mechanism includes a cage body and a roller assembly. The cage body is arranged on the outer periphery of the inner sprag and is provided with a receiving groove. The roller assembly includes a plurality of rollers, and each receiving groove is provided with a roller. One of the cage body and the inner sprag is provided with a limiting protrusion, and the other is provided with a limiting groove, and the limiting protrusion extends into the limiting groove. Through the arrangement of the limiting protrusion and the limiting groove, when the cage body moves relative to the inner sprag, the limiting groove will limit the limiting protrusion, preventing the roller from disengaging from the corresponding clutch groove, ensuring effective and stable transmission. By adopting the above cage mechanism, the overrunning clutch can prevent the roller from rolling out of the corresponding clutch groove during the wedging state operation, causing unstable transmission and affecting the service life; during the overrunning state operation, it can reduce the wear of the outer sprag paired with the inner sprag.

Description

Technical Field

[0001] The present invention belongs to the technical field of clutches, and particularly relates to a cage mechanism, an overrunning clutch, and an electric power assist system. Background Art

[0002] Since an electric power-assisted vehicle has a dual drive of motor assistance and human pedal force, an overrunning clutch is provided at the combined part of the pedal bottom bracket and the sprocket output for power transmission and separation. A roller overrunning clutch is a transmission device that unidirectionally transmits mechanical power through roller raceways, and realizes the engagement or separation of mechanical transmission by utilizing the speed difference between the inner star wheel and the outer star wheel.

[0003] Clutch grooves are formed on the inner star wheel, which can be wedged or separated from the rollers to achieve the clutch function. In the case of high-speed transmission, the rollers may roll from the corresponding clutch grooves to adjacent clutch grooves due to excessive wedging force. If this situation often occurs, on the one hand, the walls of the clutch grooves of the inner star wheel are prone to deformation, and in severe cases, it will lead to transmission failure; on the other hand, it will cause the clutch to vibrate during transmission, easily resulting in loose fitting between the cage and the inner star wheel.

[0004] Therefore, it is urgent to design a cage mechanism, an overrunning clutch, and an electric power assist system to solve the problem of the rollers rolling into other clutch grooves. Summary of the Invention

[0005] One object of the present invention is to provide a cage mechanism that can prevent the rollers from rolling out of the corresponding clutch grooves.

[0006] Another object of the present invention is to provide an overrunning clutch that can limit the rollers from rolling into other clutch grooves, reduce the wear of the inner star wheel, and achieve smooth transmission.

[0007] Still another object of the present invention is to provide an electric power assist system whose overrunning clutch has a long service life and stable transmission, improving the user experience.

[0008] To achieve the above object, the present invention adopts the following technical solutions:

[0009] A cage mechanism for an overrunning clutch, the overrunning clutch including an inner star wheel, the cage mechanism comprising:

[0010] A frame body surrounding the outer periphery of the inner star wheel, and a plurality of receiving grooves are formed on the frame body and distributed along its circumferential direction; and

[0011] The roller assembly includes a plurality of rollers, and one of the above-mentioned rollers is accommodated in each of the above-mentioned accommodation grooves; a clutch groove is formed on the outer circumference of the above-mentioned inner star wheel, and the clutch grooves are arranged in one-to-one correspondence with the above-mentioned rollers. At least part of the above-mentioned rollers are located in the clutch grooves. The inner star wheel can rotate to wedge or separate the above-mentioned rollers from the clutch grooves. A limit protrusion is provided on one of the above-mentioned frame body and the above-mentioned inner star wheel, and a limit groove is formed on the other. The limit protrusion extends into the limit groove to prevent the above-mentioned rollers from disengaging from the corresponding clutch grooves.

[0012] Optionally, at least two of the above-mentioned limit protrusions are provided, and the two above-mentioned limit protrusions are evenly arranged along the circumferential direction of the above-mentioned frame body or the two above-mentioned limit protrusions are evenly arranged along the circumferential direction of the above-mentioned inner star wheel. The above-mentioned limit grooves are arranged in one-to-one correspondence with the above-mentioned limit protrusions.

[0013] Optionally, the material of the above-mentioned frame body is metal or plastic.

[0014] Optionally, the above-mentioned cage mechanism further includes a pre-tightening member. One end of the pre-tightening member is connected to the above-mentioned frame body, and the other end is connected to the above-mentioned inner star wheel. The pre-tightening member is configured to wedge the stationary above-mentioned rollers with the above-mentioned inner star wheel.

[0015] Optionally, the above-mentioned pre-tightening member is a spring.

[0016] Optionally, hooks are provided at both ends of the above-mentioned pre-tightening member, and the hooks can be hooked on the above-mentioned frame body or the above-mentioned inner star wheel.

[0017] Optionally, at least two of the above-mentioned pre-tightening members are provided, and the two above-mentioned pre-tightening members are evenly distributed on the circumferential side of the above-mentioned inner star wheel.

[0018] The overrunning clutch includes an inner star wheel. The overrunning clutch further includes the above-mentioned cage mechanism, and the cage mechanism is sleeved outside the inner star wheel.

[0019] Optionally, the vertical wall of the above-mentioned clutch groove includes a wedging end and a separating end with a smooth transition. The distance from the separating end to the center of the inner star wheel is less than the distance from the wedging end to the center of the inner star wheel. The wedging end of the vertical wall of each separating end and the adjacent clutch groove is in smooth transition.

[0020] The electric power assist system includes the above-mentioned overrunning clutch.

[0021] The beneficial effects of the present invention are as follows:

[0022] The present invention provides a cage mechanism. Through the arrangement of the limiting protrusions and limiting grooves, when the cage moves relative to the inner sprag, the cage can provide a constraint reaction force to the rollers due to being limited, preventing the rollers from flipping over from the corresponding clutch grooves. The rollers can only rotate within a small range. That is, when the rollers tend to roll out to other clutch grooves, the limiting grooves will limit the limiting protrusions, so that the rollers can only move within the corresponding clutch grooves, avoiding the rollers from disengaging from the corresponding clutch grooves, ensuring effective transmission, and preventing the rollers from rolling in adjacent clutch grooves, that is, avoiding significant vibrations of the clutch and ensuring smooth transmission. On the other hand, when working in the overrunning state, it can reduce the wear of the outer sprag paired with the inner sprag.

[0023] The present invention provides an overrunning clutch. By adopting the above-mentioned cage mechanism, when working in the wedging state, it can prevent the rollers from flipping out of the corresponding clutch grooves, causing unstable transmission and affecting the service life. When working in the overrunning state, it can reduce the wear of the outer sprag paired with the clutch.

[0024] The present invention provides an electric power assist system. By adopting the above-mentioned overrunning clutch, it has a longer service life, stable transmission, and improves the customer experience. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 is a schematic structural view of the cage mechanism provided by an embodiment of the present invention Figure 1 ;

[0026] Figure 2 is a schematic structural view of the cage mechanism provided by an embodiment of the present invention Figure 2 .

[0027] In the figure:

[0028] 10. Cage; 11. Accommodating groove; 12. Limiting protrusion; 13. First hook hole;

[0029] 20. Roller assembly; 21. Roller;

[0030] 30. Preloading member; 31. Hook;

[0031] 200. Inner sprag; 210. Clutch part; 211. Clutch groove; 2111. Wedging end; 2112. Separation end; 220. Flange; 221. Limiting groove; 222. Second hook hole; 230. Shaft part. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0032] The present invention will be further described in detail below with reference to the drawings and embodiments. It can be understood that the specific embodiments described herein are only used to explain the present invention, rather than limiting the present invention. In addition, it should be noted that for the sake of description, only the parts related to the present invention are shown in the drawings, rather than all the structures.

[0033] In the description of the present invention, unless otherwise clearly defined and limited, the terms "connected", "connected to", and "fixed" shall be understood in a broad sense. For example, it may be a fixed connection, a detachable connection, or integrated; it may be a mechanical connection or an electrical connection; it may be directly connected or indirectly connected through an intermediate medium, and it may be the internal communication of two components or the interaction relationship between two components. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0034] In the present invention, unless otherwise clearly defined and limited, the first feature being "above" or "below" the second feature may include the direct contact between the first and second features, or may include the situation where the first and second features are not in direct contact but in contact through other features therebetween. Moreover, the first feature being "above", "over", and "on top of" the second feature includes that the first feature is directly above and obliquely above the second feature, or merely means that the horizontal height of the first feature is higher than that of the second feature. The first feature being "below", "beneath", and "underneath" the second feature includes that the first feature is directly below and obliquely below the second feature, or merely means that the horizontal height of the first feature is lower than that of the second feature.

[0035] In the description of this embodiment, the orientation or positional relationships such as "above", "below", "right", etc. are based on the orientation or positional relationship shown in the drawings, and are only for the convenience of description and simplifying the operation, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus should not be construed as a limitation to the present invention. In addition, the terms "first" and "second" are only used for distinction in description and have no special meaning.

[0036] The overrunning clutch is a basic component that emerged with the development of mechatronic products. It is an important component for power transmission and separation between the prime mover and the working machine or between the driving shaft and the driven shaft inside the machine. It is a device with a self-clutching function that utilizes the speed change or rotation direction change of the driving and driven parts. The roller overrunning clutch is a common type of overrunning clutch. The roller overrunning clutch includes an inner star wheel, an outer star wheel, and a cage mechanism. The cage mechanism includes a cage body and a roller assembly. The cage body surrounds the outer periphery of the inner star wheel. The roller assembly includes a plurality of rollers. The rollers are arranged on the cage body. When the inner star wheel is in a state of high-speed transmission, the rollers are respectively wedged with the inner star wheel and the outer star wheel, so that the inner star wheel can drive the outer star wheel to rotate. When there is a speed difference between the inner star wheel and the outer star wheel, the rollers are separated from the inner star wheel and the outer star wheel. When in high-speed transmission, the rollers may roll from the corresponding groove to the adjacent groove due to excessive wedging force. If this situation often occurs, on the one hand, the clutch groove wall of the inner star wheel is prone to deformation, and in severe cases, it will lead to transmission failure; on the other hand, it will cause the clutch to vibrate during transmission, resulting in unstable transmission.

[0037] To solve the above problems, this embodiment provides a cage mechanism that can limit the rollers 21 from rolling into other clutch grooves 211, reduce the wear of the inner star wheel 200, and achieve smooth transmission. As Figure 1 shown, a plurality of receiving grooves 11 distributed along the circumferential direction thereof are formed on the cage body 10. Each receiving groove 11 houses a roller 21. Clutch grooves 211 are formed on the outer periphery of the inner star wheel 200. The clutch grooves 211 are arranged in one-to-one correspondence with the rollers 21. At least part of the rollers 21 are located in the clutch grooves 211. The inner star wheel 200 can rotate to wedge or separate the rollers 21 from the clutch grooves 211. A limiting protrusion 12 is provided on the cage body 10, and a limiting groove 221 is formed on the inner star wheel 200. The limiting protrusion 12 extends into the limiting groove 221 to prevent the roller 21 from disengaging from the corresponding clutch groove 211. Through the arrangement of the limiting protrusion 12 and the limiting groove 221, when the cage body 10 moves relative to the inner star wheel 200, the cage body 10 can provide a constraint reaction force to the roller 21 to prevent the roller 21 from turning over from the corresponding clutch groove 211 due to being limited. The roller 21 can only rotate within a small range. That is, when the roller 21 has a tendency to roll out to other clutch grooves 211, the limiting groove 221 will limit the limiting protrusion 12, so that the roller 21 can only move within the corresponding clutch groove 211, avoiding the roller 21 from disengaging from the corresponding clutch groove 211, ensuring effective transmission, and preventing the roller 21 from rolling in the adjacent clutch grooves 211, that is, avoiding large vibrations of the clutch and ensuring smooth transmission; on the other hand, when working in the overrunning state, due to the cooperation of the limiting protrusion 12 and the limiting groove 221, the cage body 10 can only move in the limiting groove 221, thereby preventing the relative sliding of the roller 21 with both the inner star wheel 200 and the outer star wheel; it can reduce wear.

[0038] In other embodiments, a limiting protrusion 12 can also be provided on the inner sprag 200, and a limiting groove 221 is formed on the frame body 10, which can also achieve the effect of limiting, and is not limited herein.

[0039] Optionally, as Figure 1 shown, the inner sprag 200 includes a clutch portion 210, a flange 220 and a shaft portion 230 that are sequentially connected and coaxial. The flange 220 protrudes radially along the circumference of the connection with the clutch portion 210, and the limiting groove 221 is formed on the flange 220.

[0040] Preferably, at least two limiting protrusions 12 are provided, and the at least two limiting protrusions 12 are uniformly arranged along the circumferential direction of the frame body 10, and the limiting grooves 221 are arranged in one-to-one correspondence with the limiting protrusions 12. The arrangement of the two limiting protrusions 12 can improve the overall balance of the limit. It should be noted that when the limiting protrusion 12 is provided on the inner sprag 200, the two limiting protrusions 12 are uniformly arranged along the circumferential direction of the inner sprag 200, and the effect is the same as the above solution, and is not limited herein.

[0041] Optionally, the material of the frame body 10 is metal or plastic, and the materials are easy to obtain and the cost is low.

[0042] In a common roller 21 overrunning clutch, each roller 21 is preloaded with a separate part, which can achieve the preloading of each roller 21. However, the installation of multiple parts of this overrunning clutch is troublesome and occupies a large space, resulting in a relatively large overall structural size of the overrunning clutch and being inconvenient for installation and use. To solve the above problems, the cage mechanism of this embodiment further includes a preloading member 30. One end of the preloading member 30 is connected to the frame body 10, and the other end of the preloading member 30 is connected to the inner sprag 200. The preloading member 30 is configured to wedge the stationary roller 21 with the inner sprag 200. By providing the preloading member 30, the number of parts can be reduced, the installation steps can be simplified, and space can be saved.

[0043] Specifically, the preloading member 30 has elasticity, and the elasticity of the preloading member 30 is used to wedge the roller 21 with the inner sprag 200. As Figure 1 shown, the preloading member 30 is a spring. In other embodiments, the preloading member 30 can also be other elastic parts. Optionally, hooks 31 are provided at both ends of the preloading member 30, and the hooks 31 can be hooked on the frame body 10 or the inner sprag 200 to realize the connection between the preloading member 30 and the frame body 10 and the inner sprag 200. Specifically, as Figure 1As shown, a first hook hole 13 is formed on the frame body 10. The hook 31 at one end of the spring passes through the first hook hole 13 to be connected to the frame body 10. A second hook hole 222 is formed on the flange 220. The hook 31 at the other end of the spring passes through the second hook hole 222 to be connected to the flange 220. By providing the first hook hole 13 and the second hook hole 222, the connection between the pre-tightening member 30, the frame body 10 and the inner sprag 200 is realized.

[0044] Preferably, an annular groove for accommodating the pre-tightening member 30 is formed between the flange 220 and the clutch portion 210, which plays an axial limiting role on the pre-tightening member 30 to prevent the pre-tightening member 30 from detaching from the inner sprag 200.

[0045] Preferably, at least two pre-tightening members 30 are provided, and the at least two pre-tightening members 30 are evenly distributed on the circumferential side of the inner sprag 200, which improves the uniformity of the force applied by the pre-tightening members 30 and makes the circumferential force on the frame body 10 or the inner sprag 200 more balanced.

[0046] This embodiment also provides an overrunning clutch. The above overrunning clutch includes an inner sprag 200 and the above-mentioned cage mechanism. The above-mentioned cage mechanism is sleeved outside the inner sprag 200. By adopting the above-mentioned cage mechanism, when working in the wedging state, it is possible to prevent the roller 21 from rolling out of the corresponding clutch groove 211, resulting in unstable transmission and affecting the service life; when working in the overrunning state, it can reduce the wear on the outer sprag paired with the inner sprag.

[0047] Optionally, as Figure 1 and Figure 2 shown, the vertical wall of the clutch groove 211 of the inner sprag 200 includes a wedging end 2111 and a separating end 2112 with a smooth transition. The distance from the separating end 2112 to the center of the inner sprag 200 is less than the distance from the wedging end 2111 to the center of the inner sprag 200. Each separating end 2112 has a smooth transition with the wedging end 2111 of the vertical wall of the adjacent clutch groove 211. When the clutch needs to transmit power, the roller 21 is stuck in the wedging end 2111 to achieve power transmission. When there is a speed difference between the inner sprag 200 and the outer sprag (not shown in the figure), the roller 21 is located at the separating end, and the power transmission between the inner sprag 200 and the outer sprag is disconnected. It should be noted that the above setting of the vertical wall of the clutch groove 211 is only one form of realizing the clutch, and there are many other forms of specifically realizing the clutch, which will not be elaborated here.

[0048] This embodiment also provides an electric power assist system. By adopting the above overrunning clutch, it has a longer service life, stable transmission, and improves the customer's usage experience.

[0049] Obviously, the embodiments of the present invention are merely examples for clearly illustrating the present invention, rather than limitations on the implementation manners of the present invention. For those of ordinary skill in the art, various obvious changes, re-adjustments and substitutions can be made without departing from the protection scope of the present invention. It is not necessary and impossible to enumerate all the implementation manners here. Any modifications, equivalent substitutions and improvements made within the spirit and principle of the present invention shall be included within the protection scope of the claims of the present invention.

Claims

1. A cage mechanism for an overrunning clutch, the overrunning clutch including an inner sprag (200), characterized in that, The cage mechanism includes: A cage body (10) surrounding the outer periphery of the inner star wheel (200), and a plurality of receiving grooves (11) distributed along the circumferential direction of the cage body (10) are formed on the cage body (10); and A roller assembly (20) including a plurality of rollers (21), and one of the rollers (21) is received in each of the receiving grooves (11); a clutch groove (211) is formed on the outer periphery of the inner star wheel (200), and the clutch grooves (211) are arranged in one-to-one correspondence with the rollers (21). At least a part of the rollers (21) are located in the clutch grooves (211). The inner star wheel (200) can rotate to wedge or separate the rollers (21) from the clutch grooves (211). A limiting protrusion (12) is provided on the cage body (10), and a limiting groove (221) is formed on the inner star wheel (200). The limiting protrusion (12) extends into the limiting groove (221). The inner star wheel (200) includes a clutch part (210), a flange (220), and a shaft part (230) that are connected in sequence and coaxially. The flange (220) protrudes radially along the circumference of the connection part of the clutch part (210), and the limiting groove (221) is formed on the flange (220).

2. The cage mechanism according to claim 1, wherein, At least two limiting protrusions (12) are provided. The two limiting protrusions (12) are evenly arranged along the circumferential direction of the cage body (10) or the two limiting protrusions (12) are evenly arranged along the circumferential direction of the inner star wheel (200). The limiting grooves (221) are arranged in one-to-one correspondence with the limiting protrusions (12).

3. The cage mechanism according to claim 1, wherein, The material of the cage body (10) is metal or plastic.

4. The cage mechanism according to any one of claims 1-3, characterized in that, The cage mechanism further includes a pre-tightening member (30). One end of the pre-tightening member (30) is connected to the cage body (10), and the other end is connected to the inner star wheel (200). The pre-tightening member (30) is configured to wedge the stationary rollers (21) with the inner star wheel (200).

5. The cage mechanism according to claim 4, characterized in that, The pre-tightening member (30) is a spring.

6. The cage mechanism according to claim 5, characterized in that, Hooks (31) are provided at both ends of the pre-tightening member (30), and the hooks (31) can be hooked on the cage body (10) or the inner star wheel (200).

7. The cage mechanism according to claim 5, characterized in that, At least two pre-tightening members (30) are provided, and the two pre-tightening members (30) are evenly distributed on the circumferential side of the inner star wheel (200).

8. Overrunning clutch, including an inner star wheel (200), characterized in that, The overrunning clutch further includes the cage mechanism according to any one of claims 1-7, and the cage mechanism is sleeved outside the inner star wheel (200).

9. The overrunning clutch according to claim 8, characterized in that, The vertical wall of the clutch groove (211) includes a wedging end (2111) and a separating end (2112) with a smooth transition. The distance from the separating end (2112) to the center of the inner star wheel (200) is less than the distance from the wedging end (2111) to the center of the inner star wheel (200). The wedging end (2111) of the vertical wall of each separating end (2112) and the adjacent clutch groove (211) has a smooth transition.

10. An electric power assist system, characterized in that, An overrunning clutch according to claim 8 or 9 is included.

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