Power steering booster

Abstract

Power steering booster with: a case; a motor that is mounted in the housing and designed to generate a rotational force; a sun wheel designed to be rotated by the motor; a ring gear that is mounted in the housing and arranged around the sun gear; a carrier designed to rotate through the engagement between the sun gear and the ring gear, with a steering shaft locked to a steering wheel mounted on the carrier; and an elastic relaxation element mounted on the carrier to reduce play.

Description

BACKGROUND AREA

[0001] Example embodiments of the present disclosure relate to a steering booster, and more particularly, to a steering booster capable of improving steering feel and reducing gear transmission error and operating noise by minimizing backlash in a planetary gear. DESCRIPTION OF THE RELATED PRIOR ART

[0002] As autonomous vehicle technology advances, steering systems are expected to transition from EPS systems to steer-by-wire (SBW) systems. The SBW system can slightly change the steering ratio depending on the driving situation, which can improve ride comfort and vehicle stability.

[0003] The SBW system consists of a power steering unit (SFA) and a rear wheel drive unit (RWA). The SFA provides reaction force to a steering wheel, ensuring the driver has a steering feel when turning the steering wheel. The SFA includes a steering reaction force motor and a reduction gear. By arranging the steering reaction force motor and the reduction gear coaxially with a steering column, the installation space of the SFA can be reduced and the steering wheel can be easily mounted on a dashboard.

[0004] In a conventional planetary gear reducer used in a conventional SFA, the distance between the shafts is fixed, making it difficult to apply a backlash adjuster. Furthermore, compared to a conventional worm gear or belt reducer, it is difficult to provide a steering feel due to the clearance caused by backlash between the gears. Therefore, there is a need for improvement.

[0005] The related art of the present disclosure is disclosed in Korean Patent No. 10-0530034 (filed on November 14, 2005, entitled "STEERING REPULSIVE POWER CONTROL APPARATUS OF STEER-BY-WIRE SYSTEM WHICH CONTROLLING FOR REPULSIVE POWER TORQUE BY WIDTH ACCELERATION"). OVERVIEW

[0006] An object of the present disclosure is to provide a steering booster that can improve steering feel and reduce gear transmission error and operating noise by minimizing backlash in a planetary gear.

[0007] A power steering device according to the present disclosure includes: a housing; a motor mounted in the housing and configured to provide rotational force; a sun gear configured to rotate by the motor; a ring gear mounted in the housing and arranged to surround the sun gear; a carrier configured to rotate by engagement between the sun gear and the ring gear, a steering shaft locked to a steering wheel being mounted on the carrier; and an elastic relaxation member mounted on the carrier to reduce backlash.

[0008] The sun gear may include: a sun shaft connected to the motor and configured to rotate by being coaxial with the steering shaft; and sun teeth formed on the sun shaft and configured to mesh with the carrier.

[0009] The carrier may include: a carrier body connected to the steering shaft; a plurality of carrier pins configured to penetrate the carrier body and supported on the elastic relaxation member; a planetary gear mounted on the carrier pin and configured to cause rotation of the carrier body by engagement with the sun gear and the ring gear; and a carrier fixing device configured to fix the planetary gear to the carrier body.

[0010] A support hole may be formed on the support body so that the support pin penetrates the support body, and the elastic relaxation member inserted into the support hole may be formed so as to elastically support the support pin.

[0011] The support hole and / or the support pin may be provided with a rotation limiting part designed to limit the axial rotation of the elastic relaxation part.

[0012] The elastic relaxation member may include: a first elastic portion formed to come into close contact with an inner peripheral surface of the support hole; a second elastic portion formed to come into close contact with an outer peripheral surface of the support pin; and a third elastic portion formed to connect the first elastic portion and the second elastic portion, wherein the first elastic portion and the second elastic portion are alternately arranged in a circumferential direction.

[0013] The two ends of the elastic relaxation part can be spaced apart from each other.

[0014] Both ends of the elastic relaxation member may be arranged to come into close contact with the inner peripheral surface of the support hole or the outer peripheral surface of the support pin and to oppose each other.

[0015] The elastic relaxation member may further include a fourth elastic portion formed to connect both ends of the elastic relaxation member and to be contracted by an external force and restored when the external force is released.

[0016] The two ends of the elastic relaxation part may correspond to a direction of a load acting on the support pin.

[0017] In the power steering booster according to the present disclosure, the elastic relaxation member applied to the carrier is preloaded to elastically support the carrier pin provided in the carrier, thereby suppressing the occurrence of backlash and enabling smooth load transmission to the planetary gear. This can mitigate the occurrence of noise and vibration. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 shows a schematic representation of a steering booster according to an embodiment of the present disclosure. Fig. 2 shows a schematic representation of a sun gear according to an embodiment of the present disclosure. Fig. 3 is an assembled perspective view schematically showing a carrier according to an embodiment of the present disclosure. Fig. 4 is an exploded perspective view schematically showing the carrier according to an embodiment of the present disclosure. Fig. 5 is a cross-sectional view schematically showing the carrier according to an embodiment of the present disclosure. Fig. 6 shows a schematic representation of an elastic relaxation part according to an embodiment of the present disclosure. Fig. 7 shows a schematic representation of the elastic relaxation part mounted in a support hole according to an embodiment of the present disclosure. Fig. 8 is a schematic diagram illustrating a disposition of the elastic relaxation member based on a load applied to the beam according to an embodiment of the present disclosure. Fig. 9A and Fig. 9B are schematic representations of the two ends of the elastic relaxation member and the movement of the elastic relaxation member depending on the load direction according to an embodiment of the present disclosure. DETAILED DESCRIPTION

[0018] A power steering booster is described below with reference to the accompanying drawings using various exemplary embodiments. It should be noted that the thickness of individual lines or the size of individual components in the drawings may be exaggerated for clarity and simplicity of description. Furthermore, the terms used herein are defined with their functions in the present disclosure in mind, and these terms may change depending on the intent or practice of a user or operator. The terms should therefore be defined in accordance with the entirety of the present disclosure.

[0019] Fig. 1 shows a schematic representation of a steering booster according to an embodiment of the present disclosure. Referring to Fig. 1, a steering booster 1 according to an embodiment of the present disclosure may include a housing 10, a motor 20, a sun gear 30, a ring gear 40, a carrier 50, and an elastic relaxation member 60.

[0020] The housing 10 can be attached to a vehicle body. For example, the housing 10 can be located under a steering wheel 100 and fixedly mounted to the vehicle body. A pair of housings 10 can be assembled to cover internal components.

[0021] The motor 20 can be incorporated into the housing 10 and provide a rotational force. For example, the motor 20 can be driven in response to a signal from a sensor configured to detect the rotation of the steering wheel 100 and apply a reaction force to the steering wheel 100. The motor 20, configured to generate a rotational force when power is supplied, can be implemented in various embodiments.

[0022] The sun gear 30 can be rotated by the motor 20. For example, the sun gear 30 can rotate by being directly connected to the motor 20.

[0023] The ring gear 40 may be mounted in the housing 10 and arranged to surround the sun gear 30. The ring gear 40 may, for example, be formed on an inner wall of the housing 10 or be integrally incorporated into the housing 10. The ring gear 40 may be annular, and teeth may be formed along an inner circumferential surface.

[0024] The carrier 50 can rotate through the engagement between the sun gear 30 and the ring gear 40, and a steering shaft 200 connected to the steering wheel 100 can be mounted on the carrier 50. For example, the steering shaft 200 can be connected to the driver-operated steering wheel 100, and the steering shaft 200 can penetrate the housing 10 and be press-fitted into the carrier 50. The steering shaft 200 can be arranged in line with the center axis of the sun gear 30.

[0025] The elastic relaxation member 60 can be mounted on the support 50 to reduce backlash. The elastic relaxation member 60 can be made of a metal material, for example, and have an elastically deformable and resilient shape. The elastic relaxation member 60 can contract and recover depending on whether a load is applied to the support 50, thereby suppressing the occurrence of backlash. The elastic relaxation member 60 can apply a preload to the support 50.

[0026] Fig. 2 shows a schematic representation of a sun gear according to an embodiment of the present disclosure. Referring to Fig. 2, the sun gear 30 may include a sun shaft 31 and sun teeth 32 according to an embodiment of the present disclosure.

[0027] The sun shaft 31 may be connected to a rotating shaft of the motor 20 and may rotate while being arranged coaxially with the steering shaft 200. The sun shaft 31 may, for example, be inserted into the carrier 50.

[0028] The sun gears 32 can be formed on the sun shaft 31 and engage with the carrier 50. The sun gears 32 can be, for example, a gear shaped to enclose the sun shaft 31. The sun gears 32 can be pressed into the sun shaft 31 or formed integrally with the sun shaft 31.

[0029] Fig. 3 is an assembled perspective view schematically showing a carrier according to an embodiment of the present disclosure. Fig. 4 is an exploded perspective view schematically showing the carrier according to an embodiment of the present disclosure. Fig. 5 is a cross-sectional view schematically showing the carrier according to an embodiment of the present disclosure. Fig. 6 shows a schematic representation of an elastic relaxation part according to an embodiment of the present disclosure. Fig. 7 shows a schematic representation of the elastic relaxation part mounted in a support hole according to an embodiment of the present disclosure. Fig. 8 is a schematic illustration of a configuration of the elastic relaxation member based on a load applied to the support according to an embodiment of the present disclosure. Referring to the Fig. 3 to 8, the carrier 50 according to an embodiment of the present disclosure may include a carrier body 51, a carrier pin 52, a planetary gear 53, and a carrier fixing device 54.

[0030] The support body 51 may be connected to the steering shaft 200. The support body 51 may, for example, include a disc-shaped body plate 511 and a body connecting part 512 that protrudes from a central portion of the body plate 511 toward the steering shaft 200 and transmits a rotational reaction force to the steering shaft 200. The body connecting part 512 may be guided outward through the housing 10.

[0031] A plurality of support pins 52 can penetrate the support body 51 and rest on the elastic relaxation part 60. The support pin 52 can, for example, have a pin engagement portion 521 seated on the body plate 511 and a pin rod 522 extending from the pin engagement portion 521 and penetrating the body plate 511.

[0032] The planetary gear 53 can be mounted on the carrier pin 52 and, through engagement with the sun gear 30 and the ring gear 40, cause the carrier body 51 to rotate. The planetary gear 53 can, for example, be designed in two stages with teeth of different diameters. The planetary gear 53 can have a first gear 531 that engages the sun gear 32 and a second gear 532 that has a larger diameter than the first gear 531 and engages the ring gear 40. The planetary gear 53 can engage the sun gear 30 and the ring gear 40, which are fixed in position, and rotate about the carrier pin 52, which serves as a central axis, thereby causing the carrier body 51 itself to rotate.

[0033] The carrier fastening device 54 can fasten the planetary gear 53 to the carrier body 51. For example, the carrier fastening device 54 can be mounted on the carrier pin 52 so that the carrier pin 52 remains mounted on the carrier body 51.

[0034] The carrier fastening device 54 may include a flat washer 541, an elastic washer 542, and a snap ring 543 for fastening. The flat fastening washer 541 may be penetrated by the pin shaft 522 and have a flat cross-sectional shape. The flat fastening washer 542 may be penetrated by the pin shaft 522 and have a wave-curved cross-sectional shape. The elastic fastening washer 542 may be made of a highly elastic material such as spring steel. The fastening washer 543 may be mounted on the pin shaft 522 to prevent the flat fastening washer 541 and the elastic fastening washer 542 from shifting.

[0035] The elastic mounting disc 542 can elastically press the planetary gear 53 against the carrier body 51. This allows the planetary gear 53 to be brought into maximum contact with the carrier body 51, thereby minimizing play.

[0036] Furthermore, the pin engagement portion 521 can be brought into maximum contact with the body plate 511 by an elastic force of the elastic fixing disk 542. Therefore, tilting can be prevented even though the planetary gear 53 is a so-called two-stage gear in which the first gear 531 and the second gear 532 have different diameters.

[0037] A support hole 55 may be formed in the support body 51 so that the support pin 52 can penetrate into the support body 51. For example, a plurality of support holes 55 may be arranged so as to be spaced from each other in the circumferential direction of the support body 51. The plurality of support holes 55 may be formed by penetrating the support body 51 in its thickness direction. The plurality of support holes 55 may be formed at equiangular intervals with respect to a central axis of the steering shaft 200 and at equal intervals from each other. Three support holes 55 may be formed in the circumferential direction of the support body 51, and the planetary gears 53 may be mounted on the support pins 52, each penetrating the support holes 55.

[0038] The elastic relaxation member 60 can be inserted into the support hole 55 to elastically support the support pin 52. The pin engagement portion 521 can be designed, for example, such that its cross-sectional diameter is larger than the hole diameter of the support hole 55. The pin shaft 522 can be designed, for example, such that its cross-sectional diameter is smaller than the hole diameter of the support hole 55. As a result, a gap can be formed between the pin shaft 522 and the support hole 55, and the elastic relaxation member 60 can be inserted into the gap to preload the pin shaft 522.

[0039] The support hole 55 and the support pin 52 can be provided with a rotation-limiting part 70 configured to limit the axial rotation of the elastic relaxation part 60. For example, the rotation-limiting part 70 can protrude from an inner peripheral surface of the support hole 55 to limit the rotation of the support pin 52. Furthermore, the rotation-limiting part 70 can extend from the support pin 52 and be inserted into a recessed area of ​​the inner peripheral surface of the support hole 55. Furthermore, the elastic relaxation part 60 can be designed such that a suitable preload is exerted on the elastic relaxation part 60 itself during initial assembly.

[0040] The elastic relaxation member 60 according to an embodiment of the present disclosure may include a first elastic portion 61, a second elastic portion 62, and a third elastic portion 63. The first elastic portion 61 to the third elastic portion 63 may be integrally formed in the circumferential direction. The elastic relaxation member 60 may be made of an elastic material such as a spring.

[0041] The first elastic portion 61 comes into close contact with the inner peripheral surface of the support hole 55, the second elastic portion 62 comes into close contact with an outer peripheral surface of the support pin 52, and the third elastic portion 63 can connect the first elastic portion 61 and the second elastic portion 62. The first elastic portion 61 and the second elastic portion 62 can be arranged alternately in the circumferential direction. For example, the first elastic portion 61 can have a curved shape to come into point or surface contact with the inner peripheral surface of the support hole 55. For example, the second elastic portion 62 can have a curved shape to come into point or surface contact with the inner peripheral surface of the support hole 52. At least two first elastic portions 61 and at least two second elastic portions 62 can be formed at equal intervals in the circumferential direction, respectively.

[0042] The two ends of the elastic relaxation member 60 may be spaced apart from each other. For example, the elastic relaxation member 60 may form a closed portion to create a partially cut surface, or it may be molded in a shape such that both ends are spaced apart from each other.

[0043] Both ends of the elastic relaxation member 60 may be arranged to come into close contact with the inner peripheral surface of the support hole 55 or the outer peripheral surface of the support pin 52 and to oppose each other. For example, a first end 81 and a second end 82 may each be arranged to come into close contact with the outer peripheral surface of the support pin 52 and to oppose each other.

[0044] The elastic relaxation part 60 may further include a fourth elastic portion 64. The fourth elastic portion 64 may connect both ends of the elastic relaxation part 60. The fourth elastic portion 64 may be contracted by an external force and restored when the external force is removed. For example, the fourth elastic portion 64 may further connect the first end 81 and the second end 82 and be deformed when the first end 81 and the second end 82 are moved toward each other by an external force. Furthermore, when the external force is removed, additional resilience may be provided to return the first end 81 and the second end 82 to their original positions.

[0045] The two ends of the elastic relaxation part 60 may correspond to a direction of a load acting on the support pin 52. For example, three support pins 52 may be arranged at 120-degree intervals on the support body 51, and an imaginary line x extending from the support body 51 to the support pin 52 may be arranged to pass between the first end 81 and the second end 82.

[0046] Fig. 9A and Fig. 9B are schematic representations of two ends of the elastic relaxation part and the movement of the elastic relaxation part depending on the load direction according to an embodiment of the present disclosure. Referring to Fig. 9A and Fig.9B, when both ends of the elastic relaxation member 60 are arranged in the 6 o'clock direction and the load on the support pin 52 is in the 12 o'clock direction, the elastic relaxation member 60 can be deformed so that the first end 81 and the second end 82 are close to each other. When both ends of the elastic relaxation member 60 are arranged in the 6 o'clock direction and the load on the support pin 52 is also in the 6 o'clock direction, the elastic relaxation member 60 can be deformed so that the first end 81 and the second end 82 are deformed in the 6 o'clock direction.

[0047] The following describes the operation of the steering booster according to an embodiment of the present disclosure having the configuration described above.

[0048] The carrier pins 52 penetrate a plurality of carrier holes 55 formed in the carrier body 51, and the elastic release member 60 is inserted between the carrier hole 55 and the carrier pin 52 to create a preload. The sun gear 30 is arranged between the carrier pins 52, and the planetary gear 53 is mounted on the penetrating carrier pins 52 and then secured with the carrier fixing device 54.

[0049] When the motor 20 is mounted in the housing 10, and then the motor 20 is connected to the sun gear 30, the planetary gear 53 is in engagement with the sun gear 30 and the ring gear 40.

[0050] Furthermore, the two ends of the elastic relaxation part 60 are spaced apart from each other so that the first end 81 and the second end 82 move depending on the direction of a load to distribute the load. This makes an elastic section longer than in the case where the two ends are not spaced apart and form a closed curve, thereby suppressing the occurrence of plastic deformation.

[0051] Since the elastic modulus varies depending on the position of the two spaced-apart ends of the elastic relaxation part 60, a suitable mounting location is required. Since a radial gear force is smaller than a tangential gear force, the mounting location of the elastic relaxation part 60 should be in a section where the elastic modulus of the elastic relaxation part 60 is lower.

[0052] In a planetary gear, the following two points are in mesh with each other: a point between the planetary gear 53 and the sun gear 30, and a point between the planetary gear 53 and the ring gear 40. For example, if the initial assembly state of the elastic relaxation part 60 results in (-) backlash at one of the two points, a force corresponding to the amount of (-) backlash acts on the elastic relaxation part 60. In this case, a (+) backlash forms at the other of the two points. The elastic relaxation part 60 serves to move the planetary gear 53 from one point where the (-) backlash occurs to another point where the (+) backlash occurs, thereby preventing gear locking caused by the (-) backlash while maintaining a minimum backlash.Furthermore, in a conventional planetary gear, the sum of the radial forces is zero under operating conditions, so the backlash remains the same as in the original assembly state. Furthermore, in a compound planetary gear, where the sum of the radial forces is not zero, the radial forces act in the direction of the sun gear, so the condition of minimum backlash can always be met.

[0053] In conventional planetary gear transmissions, manufacturing defects such as tooth thickness variations, errors in gearing precision, deviations in the distance between the shafts, and constant meshing between the sun gear and multiple planetary gears prevent the load transmitted from a drive shaft from being evenly transmitted to the multiple planetary gears. This increases the transmission error, making the conventional planetary gear transmission prone to noise and vibration. However, in the present disclosure, when the elastic relaxation member 60 inserted into the carrier hole 55 elastically supports the carrier pin 52, the self-positioning adjustment of the carrier pin 52 enables the load to be evenly transmitted to the multiple planetary gears 53, thereby reducing the transmission error.

[0054] In the power steering device 1 according to an embodiment of the present disclosure, the elastic relaxation member 60, which is applied to the carrier 50, is preloaded to elastically support the carrier pin 52 provided in the carrier 50, thereby maintaining minimal backlash, suppressing the occurrence of gear binding, and enabling smooth load transmission to the planetary gear 53. This can mitigate the occurrence of noise and vibration.

[0055] Although the present disclosure has been described with reference to the embodiments illustrated in the drawings, the embodiments are for illustrative purposes only, and those skilled in the art will appreciate that various modifications and other equivalent embodiments are possible from the embodiments. Therefore, the true technical scope of the disclosure should be defined by the appended claims. QUOTES CONTAINED IN THE DESCRIPTION

[0000] This list of documents submitted by the applicant was generated automatically and is included solely for the convenience of the reader. This list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions. Cited patent literature

[0000] KR 10-0530034

[0005]

Claims

[1] Power steering with: a housing; a motor mounted in the housing and configured to generate a rotational force; a sun gear designed to be rotated by the motor; a ring gear mounted in the housing and arranged surrounding the sun gear; a carrier configured to rotate through engagement between the sun gear and the ring gear, a steering shaft locked to a steering wheel being mounted on the carrier; and an elastic relaxation part mounted on the carrier to reduce play. [2] A steering booster according to claim 1, wherein the sun gear comprises: a sun shaft connected to the motor and configured to rotate by being arranged coaxially with the steering shaft; and Sun teeth molded onto the sun shaft and designed to engage with the carrier. [3] A power steering device according to claim 1, wherein the carrier comprises: a support body connected to the steering shaft; a plurality of support pins configured to penetrate the support body and supported on the elastic relaxation member; a planetary gear mounted on the carrier pin and configured to cause rotation of the carrier body by engagement with the sun gear and the ring gear; and a carrier fastening device configured to fix the planetary gear to the carrier body. [4] Steering booster according to claim 3, in which a carrier hole in the carrier body is formed so that the carrier pin penetrates the carrier body, and the elastic relaxation part inserted into the support hole is designed to elastically support the support pin. [5] A power steering device according to claim 4, wherein the support hole and the support pin may be provided with a rotation limiting member adapted to limit the axial rotation of the elastic relaxation member. [6] A steering booster according to claim 4, wherein the elastic relaxation member comprises: a first elastic portion formed to come into close contact with an inner peripheral surface of the support hole; a second elastic portion formed to come into close contact with an outer peripheral surface of the support pin; and a third elastic portion configured to connect the first elastic portion and the second elastic portion, wherein the first elastic portion and the second elastic portion are arranged alternately in a circumferential direction. [7] A steering booster according to claim 6, wherein both ends of the elastic relaxation member are spaced apart from each other. [8] A power steering device according to claim 7, wherein both ends of the elastic relaxation member are arranged to come into close contact with the inner peripheral surface of the support hole or the outer peripheral surface of the support pin and to oppose each other. [9] A power steering device according to claim 7, wherein the elastic relaxation member further comprises a fourth elastic portion formed to connect both ends of the elastic relaxation member and to be contracted by an external force and restored when the external force is released. [10] A power steering device according to claim 7, wherein the two ends of the elastic relaxation member correspond to a direction of a load acting on the support pin.

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