Lower rotor assembly for a torque sensor

Abstract

A lower rotor assembly for a torque sensor includes a lower rotor overmold including at least one thermal staking structure extending from an upper surface thereof. The lower rotor assembly further includes a lower stator formed integrally with the lower rotor overmold as a single unitary component. The lower rotor assembly further includes an upper stator including at least one receiving structure, wherein each receiving structure receives a corresponding thermal staking structure of the lower rotor overmold when the upper stator is coupled to the lower stator.

Description

Technical Field

[0001] This disclosure relates to lower rotor assemblies for torque sensors, and more specifically, to lower rotor assemblies for torque sensors in electric power steering (EPS) systems of vehicles. Background Technology

[0002] Electric power steering (EPS) systems supplement the steering torque input applied to the steering wheel by the vehicle's operator. EPS systems have a controller (such as an electronic control unit) that calculates the required assistance force based on the steering torque input, steering wheel position, and vehicle speed. EPS systems also have an electric motor that uses the calculated assistance force to rotate the steering gears to control the vehicle's steering operation, thus providing the operator with a better steering experience.

[0003] The conventional method for assembling the lower rotor assembly requires inserting the PHA into the lower rotor before pressing the probe housing assembly (PHA) and the lower rotor onto the shoulder of the lower auxiliary shaft in the EPS system. The PHA may include a plastic component and a printed circuit board (PCB) coupled to that plastic component. Once the PHA and lower rotor are positioned at the shoulder of the lower auxiliary shaft, screws or the like can be used to mount the PHA to the auxiliary housing of the EPS system to secure the lower rotor to the auxiliary housing.

[0004] However, this method has several drawbacks. First, the PHA needs to be inserted into the lower rotor before it is pressed onto the shoulder of the lower auxiliary shaft. Second, after the PHA is inserted into the lower rotor, it is pressed together with the lower rotor onto the shoulder of the lower auxiliary shaft. This process requires additional tools to hold the PHA in place, making it difficult to clamp the integrated controller circuit card assembly (CCA) to the auxiliary housing. Third, because the PHA is inserted into the lower rotor before it is pressed onto the shoulder of the lower auxiliary shaft, the air gap between the PHA and the lower rotor may be difficult to control, and the pressure load on the PHA may be difficult to detect. Therefore, an improved method for assembling the lower rotor assembly is needed. Summary of the Invention

[0005] According to one embodiment, a lower rotor assembly for a torque sensor is disclosed. The lower rotor assembly may include a lower rotor over-mold comprising at least one heatstaking structure extending from its upper surface. The lower rotor assembly may further include a lower stator integrally formed with the lower rotor over-mold as a single integral component. The lower rotor assembly may further include an upper stator including at least one receiving structure, wherein, when the upper stator is coupled to the lower stator, each receiving structure receives a corresponding heatstaking structure of the lower rotor over-mold.

[0006] According to another embodiment, a lower rotor assembly for a torque sensor is disclosed. The lower rotor assembly may include a lower rotor overmolding part including at least one first thermally riveted structure extending from its upper surface and at least one second thermally riveted structure extending from its upper surface. The lower rotor assembly may also include a lower stator integrally formed with the lower rotor overmolding part as a single integral component. The lower rotor assembly may also include an upper stator. The upper stator may further include at least one first receiving structure, wherein, when the upper stator is coupled to the lower stator, each first receiving structure receives a corresponding first thermally riveted structure of the lower rotor overmolding part. The upper stator may also include at least one second receiving structure, wherein, when the upper stator is coupled to the lower stator, each second receiving structure receives a corresponding second thermally riveted structure of the lower rotor overmolding part.

[0007] According to another embodiment, a method for assembling a lower rotor assembly for a torque sensor in an electric power steering (EPS) system is disclosed. The method may include pressing a lower rotor overmolding and an integrally formed lower stator together onto a shoulder of a lower auxiliary shaft of the EPS system. The lower rotor overmolding may include at least one first thermally riveted structure extending from its upper surface. The method may further include placing a probe housing assembly (PHA) onto the surface of the lower stator while the lower stator and the lower rotor overmolding are positioned at the shoulder of the lower auxiliary shaft of the EPS system. The method may further include mounting the PHA onto the auxiliary housing of the EPS system. The method may further include coupling an upper stator to the lower stator. The upper stator may include at least one first receiving structure, wherein each first receiving structure receives a corresponding first thermally riveted structure of the lower rotor overmolding when the upper stator is coupled to the lower stator. The method may further include heating at least one first thermally riveted structure of the lower rotor overmolding to join the upper stator to the lower rotor overmolding. The method may also include cooling the lower rotor covering mold, the lower stator, and the upper stator, thereby achieving the assembly of the lower rotor assembly. Attached Figure Description

[0008] Figure 1 A schematic diagram of an electric power steering (EPS) system for a vehicle according to one or more embodiments of the present disclosure is depicted.

[0009] Figure 2 A lower rotor assembly for a torque sensor according to a first embodiment of the present disclosure is shown.

[0010] Figure 3 A lower rotor assembly for a torque sensor according to a second embodiment of the present disclosure is shown.

[0011] Figure 4 The steps associated with a method of assembling a lower rotor assembly for a torque sensor according to a first embodiment of the present disclosure are described.

[0012] Figure 5 The steps associated with a method of assembling a lower rotor assembly for a torque sensor according to a second embodiment of the present disclosure are described. Detailed Implementation

[0013] This document describes embodiments of the present disclosure. However, it should be understood that the disclosed embodiments are merely examples, and other embodiments may take various alternative forms. The figures are not necessarily drawn to scale; certain features may be exaggerated or minimized to show detail of particular components. Therefore, the specific structural and functional details disclosed herein should not be construed as limiting, but only as a representative basis for teaching those skilled in the art to adopt the embodiments in various ways. As will be understood by those skilled in the art, various features illustrated and described with reference to any of the figures may be combined with features illustrated in one or more other figures to produce embodiments not explicitly illustrated or described. The combinations of features shown provide representative embodiments for typical applications. However, for a particular application or implementation, various combinations and modifications of features consistent with the teachings of this disclosure may be desired.

[0014] The present disclosure relates to a lower rotor assembly, and more specifically, to a lower rotor assembly for a torque sensor in a vehicle's electric power steering (EPS) system. Figure 1 A schematic diagram depicts an electric power steering (EPS) system for a vehicle according to one or more embodiments of the present disclosure. Figure 1 As shown, the EPS system 10 may include a steering mechanism 12, a motor 14 mounted on the steering mechanism 12, and an electronic control unit (ECU) 16 that communicates electronically with the steering mechanism 12 and the motor 14.

[0015] Specifically, the steering mechanism 12 may include a steering wheel 18 connected to the steering shaft 20 of the EPS system. The vehicle operator can control the direction of the vehicle by manipulating the steering wheel 18 (i.e., by applying a steering torque input to the steering wheel 18). The steering mechanism 12 may also include a steering angle sensor 22 disposed on the steering shaft 20, configured to detect the rotation angle of the steering wheel 18 when the operator manipulates it. The steering mechanism 12 may also include a torque sensor 24 disposed on the steering shaft 20, configured to detect the steering torque input applied to the steering wheel 18 by the vehicle operator. The steering mechanism 12 may also include a reduction gear 26 disposed on the steering shaft 20, configured to reduce the rotational speed of the steering shaft 20 (i.e., reduce the steering torque input required from the operator).

[0016] refer to Figure 1 The motor 14 can be mounted on the reduction gear 26 of the steering mechanism 12. The motor 14 can use an auxiliary force to rotate the reduction gear 26, which reduces the manual steering effort required to assist steering operation by providing steering torque input by the operator.

[0017] In addition, such as Figure 1 As shown, ECU 16 can electronically communicate with steering mechanism 12. Therefore, ECU 16 can receive data from steering mechanism 12. Specifically, ECU 16 can receive data on the rotation angle of steering wheel 18 from steering angle sensor 22, and can also receive data on steering torque input provided by the operator from torque sensor 24. Furthermore, ECU 16 can electronically communicate with vehicle speed sensor 28, which detects the vehicle's speed while the vehicle is running. Therefore, ECU 16 can receive data on the vehicle's speed from vehicle speed sensor 28. Based on all the data received from steering angle sensor 22, torque sensor 24, and vehicle speed sensor 28, ECU 16 can then calculate the auxiliary force applied to reduction gear 26 to reduce the steering torque input required from the operator.

[0018] While the illustrated embodiments show a column electric power steering (CEPS) system in which electromechanical assistance is provided to a portion of the column structure, it should be understood that the embodiments disclosed herein are applicable to rack electric power steering (REPS) systems in which electromechanical assistance is provided to a steering rack. Furthermore, the embodiments disclosed herein can be used with steer-by-wire systems or systems having a mechanical connection between steering input and steering output.

[0019] Figure 2 A lower rotor assembly for a torque sensor according to a first embodiment of the present disclosure is shown. The torque sensor may be as follows: Figure 1 The torque sensor described can be used in a vehicle's EPS system to detect the steering torque input from the driver onto the steering wheel. (Reference) Figure 2 The lower rotor assembly 40 includes a lower rotor overmolding 42 and a lower stator 44 integrally formed therefrom. The lower stator 44 may be integrally formed with the lower rotor overmolding 42 as a single, integral component. The lower rotor overmolding 42 may include at least one thermally riveted structure 46 extending from the upper surface of the lower rotor overmolding 42. The thermally riveted structure 46 may be a thermally riveted rib or a thermally riveted post. The thermally riveted structure 46 may be formed of plastic.

[0020] like Figure 2 As shown, the lower rotor assembly 40 may further include an upper stator 48 independent of (i.e., structurally separate from) the lower stator 44. The upper stator 48 may be assembled onto the lower stator 44. Specifically, the upper stator 48 may include at least one receiving structure 50, wherein, when the upper stator 48 is coupled to the lower stator 44, each receiving structure receives a corresponding thermally riveted structure 46 of the lower rotor overlay molding 42.

[0021] After the upper stator 48 is coupled to the lower stator 44, a thermal riveting process can be used to fix (e.g., install) the upper stator 48 to the lower stator 44. When at least one thermal riveting structure 46 of the lower rotor overlay molding 42 is heated, the at least one thermal riveting structure 46 can change shape, thereby engaging the upper stator 48 with the lower rotor overlay molding 42, and thus with the lower stator 44.

[0022] Figure 3 A lower rotor assembly for a torque sensor according to a second embodiment of the present disclosure is shown. The torque sensor may be as follows: Figure 1 The torque sensor described can be used in a vehicle's EPS system to detect the steering torque input from the driver onto the steering wheel. (Reference) Figure 3The lower rotor assembly 60 includes a lower rotor overmolding member 62 and a lower stator 64 integrally formed therefrom. The lower stator 64 may be integrally formed with the lower rotor overmolding member 62 as a single integral component. The lower rotor overmolding member 62 may include at least one first thermally riveted structure 66 extending from the upper surface of the lower rotor overmolding member 62. The first thermally riveted structure 66 may be a thermally riveted rib. The first thermally riveted structure 66 may be formed of plastic. The lower rotor overmolding member 62 may also include at least one second thermally riveted structure 68 extending from the upper surface of the lower rotor overmolding member 62. The second thermally riveted structure 68 may be a thermally riveted post different from the first thermally riveted structure 66. The second thermally riveted structure 68 may be formed of plastic. At least one first thermally riveted structure 66 and the second thermally riveted structure 68 may be positioned alternately on the upper surface of the lower rotor overmolding member 62.

[0023] like Figure 3 As shown, the lower rotor assembly 60 may further include an upper stator 70 independent of (i.e., structurally separate from) the lower stator 64. The upper stator 70 may be assembled onto the lower stator 64. Specifically, the upper stator 70 may include at least one first receiving structure 72, wherein each first receiving structure receives a corresponding first thermally riveting structure 66 of the lower rotor overlay molding 62 when the upper stator 70 is coupled to the lower stator 64. Furthermore, the upper stator 70 may also include at least one second receiving structure 74, wherein each second receiving structure receives a corresponding second thermally riveting structure 68 of the lower rotor overlay molding 62 when the upper stator 70 is coupled to the lower stator 64. The second receiving structure 74 may be a through-hole defined by the upper stator 70.

[0024] After the upper stator 70 is coupled to the lower stator 64, the upper stator 70 can be secured (e.g., mounted) to the lower stator 64 using a thermal riveting process. When at least one first thermal riveting structure 66 and the second thermal riveting structure 68 of the lower rotor overmolding 62 are heated, the at least one first thermal riveting structure 66 and the second thermal riveting structure 68 can change shape, thereby engaging the upper stator 70 with the lower rotor overmolding 62, and thus with the lower stator 64.

[0025] Figure 4 The steps associated with a method of assembling a lower rotor assembly for a torque sensor according to a first embodiment of this disclosure are described. Figure 1 The torque sensor can be used in a vehicle's EPS system to detect the steering torque input from the vehicle operator to the steering wheel.

[0026] At stage 120, method 100 may include pressing a lower rotor overmolding 122 and an integrally formed lower stator 124 together onto a shoulder of a lower auxiliary shaft 126 of the EPS system. The lower stator 124 may be integrally formed with the lower rotor overmolding 122 as a single integral component. The lower rotor overmolding 122 may include at least one thermally riveted structure 128 extending from an upper surface of the lower rotor overmolding 122. The thermally riveted structure 128 may be a thermally riveted rib or a thermally riveted post. The thermally riveted structure 128 may be formed of plastic. Method 100 may then include placing a probe housing assembly (PHA) 130 onto the surface of the lower stator 124 while the lower stator 124 and the lower rotor overmolding 122 are positioned at the shoulder of the lower auxiliary shaft 126 of the EPS system. The PHA 130 may include a plastic member 132 that can be mounted to the auxiliary housing 134 of the EPS system. PHA 130 may also include a printed circuit board (PCB) 136 coupled to the plastic component 132. Method 100 may then include an auxiliary housing 134 for mounting PHA 130 to the EPS system. In some embodiments, screws or the like may be used to mount PHA 130 to the auxiliary housing 134.

[0027] At stage 140, method 100 may include coupling an upper stator 142 to a lower stator 124. The upper stator 142 may include at least one receiving structure 144, wherein, when the upper stator 142 is coupled to the lower stator 124, each receiving structure receives a corresponding thermally riveted structure 128 of the lower rotor overlay molding 122.

[0028] At stage 160, method 100 may include heating at least one thermally riveting structure 128 of the lower rotor overmolding 122. Upon heating, the at least one thermally riveting structure 128 may change shape to engage the upper stator 142 with the lower rotor overmolding 122, thereby engaging with the lower stator 124. Method 100 may further include cooling the lower rotor overmolding 122, the lower stator 124, and the upper stator 142 to achieve assembly of the lower rotor assembly.

[0029] Figure 5 The steps associated with a method of assembling a lower rotor assembly for a torque sensor according to a second embodiment of this disclosure are described. Figure 1 The torque sensor can be used in a vehicle's EPS system to detect the steering torque input from the vehicle operator to the steering wheel.

[0030] In stage 220, method 200 may include pressing a lower rotor overmolding 222 and an integrally formed lower stator 224 together onto a shoulder of a lower auxiliary shaft 226 of the EPS system. The lower stator 224 may be integrally formed with the lower rotor overmolding 222 as a single integral component. The lower rotor overmolding 222 may include at least one first thermally riveted structure 228 extending from the upper surface of the lower rotor overmolding 222. The first thermally riveted structure 228 may be a thermally riveted rib. The first thermally riveted structure 228 may be formed of plastic. The lower rotor overmolding 222 may also include at least one second thermally riveted structure 230 extending from the upper surface of the lower rotor overmolding 222. The second thermally riveted structure 230 may be a thermally riveted post different from the first thermally riveted structure 228. The second thermally riveted structure 230 may be formed of plastic. At least one first thermally riveted structure 228 and a second thermally riveted structure 230 may be positioned alternately on the upper surface of the lower rotor overlay molding 222. Method 200 may then include placing a probe housing assembly (PHA) 232 onto the surface of the lower stator 224 while the lower stator 224 and the lower rotor overlay molding 222 are positioned at the shoulder of the lower auxiliary shaft 226 of the EPS system. PHA 232 may include a plastic member 234 that can be mounted to the auxiliary housing 236 of the EPS system. PHA 232 may also include a printed circuit board (PCB) 238 coupled to the plastic member 234. Method 200 may then include mounting PHA 232 to the auxiliary housing 236 of the EPS system. In some embodiments, PHA 232 may be mounted to the auxiliary housing 236 using screws or the like.

[0031] At stage 240, the method may include coupling an upper stator 242 to a lower stator 224. The upper stator 242 may include at least one first receiving structure 244, wherein, when coupled to the lower stator 224, each first receiving structure receives a corresponding first thermally riveting structure 228 of the lower rotor overlay molding 222. The upper stator 242 may also include at least one second receiving structure 246, wherein, when coupled to the lower stator 224, each second receiving structure receives a corresponding second thermally riveting structure 230 of the lower rotor overlay molding 222. The second receiving structure 246 may be a through-hole defined by the upper stator 242.

[0032] At stage 260, method 200 may include heating at least one first thermal riveting structure 228 and a second thermal riveting structure 230 of the lower rotor overlay molding 222. During heating, the at least one first thermal riveting structure 228 and the second thermal riveting structure 230 may change shape to engage the upper stator 242 with the lower rotor overlay molding 222, thereby engaging with the lower stator 224. Method 200 may further include cooling the lower rotor overlay molding 222, the lower stator 224, and the upper stator 242 to achieve assembly of the lower rotor assembly.

[0033] Given Figure 4 and Figure 5 Because PHA ( Figure 4 130 or Figure 5 (232) After the lower stator and lower rotor covering molded parts are pressed onto the shoulder of the lower auxiliary shaft of the EPS system, they are placed on the lower stator, so the air gap between the PHA and the lower rotor is easy to measure, and the pressure load of the PHA is also easy to detect.

[0034] Although one or more embodiments described herein employ a hot riveting process to assemble the lower rotor assembly, it is contemplated that other methods known to those skilled in the art can be used to assemble the lower rotor assembly.

[0035] While exemplary embodiments have been described above, these embodiments are not intended to describe all possible forms covered by the claims. The language used in this specification is descriptive rather than restrictive, and it should be understood that various changes may be made without departing from the spirit and scope of this disclosure. As previously stated, features of various embodiments may be combined to form other embodiments of this disclosure that may not be explicitly described or illustrated. While various embodiments may be described as providing advantages or being preferred over other embodiments or prior art implementations in one or more desired features, those skilled in the art will recognize that one or more features or characteristics may be compromised to achieve desired overall system properties, depending on the specific application and implementation. These properties include, but are not limited to, cost, strength, durability, life cycle cost, marketability, appearance, packaging, size, serviceability, weight, manufacturability, ease of assembly, etc. Therefore, in terms of one or more characteristics, any embodiment described as less desirable than that of other embodiments or prior art implementations, which are outside the scope of this disclosure and may be ideal for a particular application.

Claims

1. A lower rotor assembly for a torque sensor, the lower rotor assembly comprising: The lower rotor covering molding includes at least one first hot riveting structure extending from the upper surface of the lower rotor covering molding and at least one second hot riveting structure extending from the upper surface of the lower rotor covering molding. The lower stator is integrally formed with the lower rotor covering molded part as a single integral component; as well as Upper stator, including: At least one first receiving structure, wherein, when the upper stator is coupled to the lower stator, each first receiving structure receives a corresponding first thermally riveting structure of the lower rotor overlay molding; and At least one second receiving structure, wherein, when the upper stator is coupled to the lower stator, each second receiving structure receives a corresponding second thermally riveted structure of the lower rotor covering molded part.

2. The lower rotor assembly according to claim 1, wherein, The at least one first thermally riveted structure is formed of plastic.

3. The lower rotor assembly according to claim 1, wherein, The at least one first hot-riveting structure is a hot-riveting rib.

4. The lower rotor assembly according to claim 1, wherein, The at least one second thermally bonded structure is formed of plastic.

5. The lower rotor assembly according to claim 1, wherein, The at least one second hot-riveting structure is a hot-riveting column.

6. The lower rotor assembly according to claim 1, wherein, The at least one first hot riveting structure and the second hot riveting structure are positioned alternately on the upper surface of the lower rotor-covered molded part.

7. A method for assembling a lower rotor assembly for a torque sensor in an electric power steering system, the method comprising: The lower rotor overmolding and the lower stator integrally formed therewith are pressed together onto the shoulder of the lower auxiliary shaft of the electric power steering system, the lower rotor overmolding including at least one first thermal riveting structure extending from the upper surface of the lower rotor overmolding. When the lower stator and the lower rotor covering molded part are positioned at the shoulder of the lower auxiliary shaft of the electric power steering system, the probe housing assembly is placed on the surface of the lower stator; The probe housing assembly is mounted onto the auxiliary housing of the electric power steering system; The upper stator is coupled to the lower stator, the upper stator including at least one first receiving structure, wherein when the upper stator is coupled to the lower stator, each first receiving structure receives a corresponding first thermal riveting structure of the lower rotor covering molded part; Heating at least one first hot-riveting structure of the lower rotor overmolding to join the upper stator to the lower rotor overmolding; and The lower rotor assembly is assembled by cooling the lower rotor covering mold, the lower stator, and the upper stator.

8. The method according to claim 7, wherein, The lower stator and the lower rotor are integrally formed into a single component.

9. The method according to claim 7, wherein, The at least one first thermally riveted structure is formed of plastic.

10. The method according to claim 7, wherein, The at least one first hot-riveting structure is a hot-riveting rib.

11. The method according to claim 7, wherein, The lower rotor overmolding component further includes at least one second hot-riveting structure extending from the upper surface of the lower rotor overmolding component.

12. The method according to claim 11, wherein, The at least one second thermally bonded structure is formed of plastic.

13. The method according to claim 11, wherein, The at least one second hot-riveting structure is a hot-riveting column.

14. The method according to claim 11, wherein, The at least one first hot riveting structure and the second hot riveting structure are positioned alternately on the upper surface of the lower rotor-covered molded part.

15. The method according to claim 11, wherein, The upper stator further includes at least one second receiving structure, wherein when the upper stator is coupled to the lower stator, each second receiving structure receives a corresponding second thermally riveted structure of the lower rotor covering molded part.

16. The method according to claim 15, wherein, The at least one second receiving structure is a through-hole defined by the upper stator.

17. The method according to claim 7, wherein, The probe housing assembly includes a plastic component that can be mounted to the auxiliary housing of the electric power steering system.

18. The method according to claim 17, wherein, The probe housing assembly also includes a printed circuit board coupled to the plastic component.

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