BEVELED SNAP RING FOR ELECTRIC RACK POWER STEERING SYSTEM

Abstract

Vehicle steering assembly, comprising: a rack (40) which is displaceable and arranged within a rack housing (70), wherein the rack (40) is configured to be functionally coupled to a pair of road wheels (42); a pinion shaft (28) which is functionally coupled to the rack (40); a bearing (68) that is in contact with the pinion shaft (28) and is arranged inside the rack housing (70); and a snap ring (72) which is partially arranged within a groove (96) defined by the rack housing (70), which is substantially circular, extending from a radially inner edge (78) to a radially outer edge (80) to define a radial width of the snap ring (72), which in a first state is in contact with the bearing (68), which has an eyelet section (90, 92) which defines a hole (94), and which is movable from the first state to a second state, wherein the first state exerts pressure on the bearing (68) such that the bearing (68) is held in place, wherein the second state allows the bearing (68) to be removed from the pinion shaft (28), the snap ring (72) has a chamfered section (86) which is in contact with an outer ring (88) of the bearing (68), characterized by the fact that the eyelet section (90, 92) projects radially outwards from the radially outer edge (80) of the snap ring (72), the snap ring (72) can be pre-tensioned radially outwards from a working state into an open position, whereby in the working state the snap ring (72) presses the bearing (68) radially inwards, in the open position the snap ring (72) is brought into a position that allows the bearing (68) to be inserted for installation or pulled out for removal, and a section of the snap ring (72), including the radially outer edge (80), is arranged in the groove (96) formed by the rack housing (70), the groove (96) providing space for the eyelet section (90, 92) and for the bending of the snap ring (72) during the opening process.

Description

[0001] The present invention relates to a vehicle steering assembly according to the preamble of claim 1.

[0002] An electric power steering system (EPS system) is used to supplement the steering torque applied by a vehicle operator to the steering wheel. The EPS system has a controller (e.g., an electronic control unit) that calculates the required assistance force based on the input steering torque, steering wheel position, and vehicle speed. The EPS system also has an electric motor that rotates a steering gear with the calculated assistance force to control the vehicle's steering movements, thus providing the operator with an enhanced steering experience.

[0003] A lower rotor assembly of the EPS system comprises a lower rotor and a probe housing assembly (PHA). The PHA may include a plastic component and a printed circuit board (PCB) bonded to the plastic component. The lower rotor is coupled to a pinion shaft assembly in an EPS rack and pinion configuration, with the pinion shaft assembly at least partially guided by a bearing. A circlip is provided to hold the bearing in place within the rack housing. However, it is difficult to disassemble the pinion shaft assembly from the EPS rack because the circlip is located beneath the lower rotor and the PHA. The conventional arrangement of the parts leaves little to no room to remove the circlip without destroying the PHA.The snap ring can be removed after the lower rotor and one upper rotor have been removed from the pinion shaft, but the PHA and possibly the rotors will need to be replaced with new components after servicing or replacing the snap ring. Therefore, an assembly that avoids replacing additional parts during disassembly would be desirable.

[0004] JP 2015 - 113 849 A discloses a steering assembly according to the preamble of claim 1.

[0005] From JP 2010 - 38 254 A, a vehicle steering assembly is known, comprising: a rack which is displaceable and arranged within a rack housing, wherein the rack is configured to be functionally coupled to a pair of road wheels; a pinion shaft which is functionally coupled to the rack; a bearing which is in contact with the pinion shaft and is arranged within the rack housing;and a snap ring, which is partially arranged within a groove defined by the rack housing, which is substantially circular, extending from a radially inner edge to a radially outer edge to define a radial width of the snap ring, which in a first state is in contact with the bearing, which has a lug section defining a hole, and which is movable from the first state to a second state, wherein the first state exerts pressure on the bearing such that the bearing is held in place, and wherein the second state allows the bearing to be removed from the pinion shaft. The snap ring has a chamfered section.

[0006] JP H06-58220 U discloses a vehicle steering assembly comprising: a rack that is slidably arranged within a rack housing, the rack being configured to be functionally coupled to a pair of road wheels; a pinion shaft that is functionally coupled to the rack; a bearing that is in contact with the pinion shaft and is arranged within the rack housing;and a snap ring, which is partially arranged within a groove defined by the rack housing, which is substantially circular, extending from a radially inner edge to a radially outer edge to define a radial width of the snap ring, which in a first state is in contact with the bearing, which has two eyelet sections, each defining a hole, and which is movable from the first state to a second state, wherein the first state exerts pressure on the bearing such that the bearing is held in place, and wherein the second state allows the bearing to be removed from the pinion shaft. The snap ring has a chamfered section. The eyelet sections project radially outward from the radially outer edge of the snap ring.

[0007] The object of the present invention is to provide a vehicle steering assembly that is easier to maintain.

[0008] This problem is solved by a vehicle steering assembly having the features of claim 1.

[0009] Advantageous embodiments are specified in the dependent claims. SUMMARY OF THE REVELATION

[0010] According to one aspect of the disclosure, a vehicle steering assembly comprises a rack that is displaceably arranged within a rack housing, the rack being configured to be functionally coupled to a pair of road wheels. The vehicle steering assembly also comprises a pinion shaft that is functionally coupled to the rack. The vehicle steering assembly further comprises a bearing that is in contact with the pinion shaft and is arranged within the rack housing.The vehicle steering assembly also includes a snap ring which is partially arranged within a groove defined by the rack housing, wherein the snap ring is in contact with the bearing in a first state, wherein the snap ring has an eyelet section which defines a hole, wherein the snap ring is movable from the first state to a second state, wherein the first state exerts pressure on the bearing such that the bearing is held in place, wherein the second state allows the bearing to be removed from the pinion shaft.

[0011] According to another aspect of the disclosure, a vehicle steering assembly comprises a rack that is displaceably arranged within a rack housing, the rack being configured to be functionally coupled to a pair of road wheels. The vehicle steering assembly also comprises a pinion shaft that is functionally coupled to the rack. The vehicle steering assembly further comprises a bearing that is in contact with the pinion shaft and is arranged within the rack housing. The vehicle steering assembly also comprises a snap ring that is partially arranged in a groove defined by the rack housing, the snap ring being in contact with the bearing in a first state, the snap ring having a chamfered section that is in contact with an outer ring of the bearing.

[0012] These and other advantages and features will become clearer from the following description in conjunction with the drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] The subject matter, which is considered the invention, is specifically highlighted and claimed in detail in the claims at the end of the description. The foregoing and further features and advantages of the invention will become clear from the following detailed description in conjunction with the accompanying drawings, in which: Fig. 1 is a schematic representation of an electric rack and pinion power steering system; Fig. 2 a cross-sectional view of the electric rack and pinion power steering system at an interface between pinion shaft and bearing with a snap ring; Fig. 3 an enlarged view of a section of Fig. 2 is the one that shows the interface between the snap ring and the bearing; Fig. 4 is a perspective view of the snap ring; Fig. 5 is a cross-sectional view of the electric rack and pinion power steering system with the snap ring in an installation position; and Fig. Figure 6 shows a cross-sectional view of the electric rack and pinion power steering system with the snap ring opening for disassembly. DETAILED DESCRIPTION

[0014] Now, with reference to the figures in which the invention is described with reference to certain embodiments, without limiting them, an electric power steering system (EPS system) is disclosed. In particular, the EPS system comprises a subassembly that can be disassembled without having to replace any components.

[0015] The embodiments described here are used in conjunction with a steering system of a vehicle, such as a passenger car, truck, sport utility vehicle, crossover, minivan, watercraft, aircraft, off-road vehicle, recreational vehicle or other suitable vehicles, which include various steering system schemes.

[0016] First, with reference to Fig. Figure 1 shows a power steering system 20 in general terms. The power steering system 20 can be configured as a driver interface steering system, an autonomous driving system, or a system that enables both driver interface steering and autonomous steering. The steering system can include an input device 22, such as a steering wheel, wherein a driver can mechanically provide a steering input by turning the steering wheel. A steering column 26 extends along an axis from the input device 22 to an output assembly 28. The steering column 26 includes one or more sleeves. The embodiments disclosed here are used in steering systems in which the output assembly 28 is functionally connected to a linear translational component 40, which in some embodiments is a rack.The output assembly 28 is a pinion shaft that engages with the rack 40 and can be referred to as either the output assembly or the pinion shaft. The rack 40 pivots the steering wheels 42 to steer the vehicle. One or more sensors detect the angle and torque of the steering column components in conjunction with steering inputs made by the operator. An ECU can receive the sensor inputs and electronically transmit an assist force, which is applied to the rack 40 by an assist mechanism 50 to reduce the steering torque required by the operator.

[0017] Although the embodiments shown depict an electric rack and pinion power steering system (REPS system) in which the electromechanical assistance is provided at a section of the rack structure, it is understood that the embodiments disclosed herein may also be applicable to a steer-by-wire steering system.

[0018] Fig. Figure 2 shows a lower rotor assembly 60 for a torque sensor according to an embodiment of the present disclosure. The torque sensor can be the one associated with Fig. The torque sensor described in Section 1 can be used in a vehicle's REPS system to detect steering torque applied by an operator to a steering wheel. The lower rotor assembly 60 is attached to the pinion shaft 28. A probe housing assembly 64 contains a probe that detects an electric or magnetic field generated during the rotation of the lower rotor assembly 60. A bearing 68 is in contact with a section of the pinion shaft 28. The lower rotor assembly 60, the bearing 68, and the pinion shaft 28 are arranged in a rack housing 70. The bearing 68 is held in place, at least partially, by a snap ring 72. The snap ring 72 also eliminates backlash in the entire pinion shaft assembly.

[0019] Now, with reference to Fig. 3 is an enlarged section of Fig. Figure 2 shows. In particular, a section of bearing 68 and snap ring 72 are shown in more detail. Fig. Figure 4 shows the snap ring 72 in a perspective view to illustrate further details of the snap ring 72.

[0020] The snap ring 72 is essentially circular, with a break that forms a gap between a first end 74 and a second end 76 of the snap ring 72 to define its length. The snap ring 72 extends from a radially inner edge 78 to a radially outer edge 80 to define its radial width. The snap ring 72 also extends from a first side 82 to a second side 84 to define its thickness. The snap ring 72 has a chamfered section 86 on the second side 84. The chamfered section 86 is in contact with an outer ring 88 of the bearing 68. The contact between the chamfered section 86 and the outer ring 88 holds the bearing 68 in place.The chamfered section 86 is an angled section that allows the snap ring 72 to push the bearing 68 radially inwards and downwards / forwards in one vehicle direction.

[0021] The snap ring 72 comprises at least one eyelet section that projects radially outward from the radially outer edge 80 of the snap ring 72. In the illustrated embodiment, a pair of eyelet sections is shown, namely a first eyelet section 90 and a second eyelet section 92. The eyelet sections 90, 92 can be formed from various conceivable shapes that may deviate from the geometry shown. Regardless of the specific geometry, each eyelet section 90, 92 has a hole 94 into which a tool can be inserted to facilitate handling the snap ring 72 in the installed state. In particular, the snap ring 72 can be opened from a "working" state ( Fig. 5) radially outwards into an “open” position ( Fig. 6) be pre-tensioned. In the working state of Fig. 5. The snap ring 72 presses the bearing 68 radially inwards and downwards / forwards in one direction of the vehicle, as described above. In the open position of Fig. 6 The snap ring 72 is brought into a position that allows the bearing 68 to be inserted for installation or pulled out for removal without damaging other components.

[0022] A section of the snap ring 72, including its radially outer edge 80, is arranged in a groove 96 formed by the rack housing 70. The groove 96 provides space for the eyelet sections 90 and 92 and for the bending of the snap ring 72 during the opening process described in detail here.

[0023] The snap ring 72 revealed here allows a tool to open the snap ring 72 in a small space, thus avoiding the disposal of other components for a bearing removal process.

Claims

[1] Vehicle steering assembly comprising: a rack (40) which is displaceable and arranged within a rack housing (70), wherein the rack (40) is configured to be functionally coupled to a pair of road wheels (42); a pinion shaft (28) which is functionally coupled to the rack (40); a bearing (68) that is in contact with the pinion shaft (28) and is arranged inside the rack housing (70); and a snap ring (72) which is partially arranged within a groove (96) defined by the rack housing (70), which is substantially circular, extending from a radially inner edge (78) to a radially outer edge (80) to define a radial width of the snap ring (72), which in a first state is in contact with the bearing (68), which has an eyelet section (90, 92) which defines a hole (94), and which is movable from the first state to a second state, wherein the first state exerts pressure on the bearing (68) such that the bearing (68) is held in place, wherein the second state allows the bearing (68) to be removed from the pinion shaft (28), the snap ring (72) has a chamfered section (86) which is in contact with an outer ring (88) of the bearing (68), characterized by , that the eyelet section (90, 92) projects radially outwards from the radially outer edge (80) of the snap ring (72), the snap ring (72) can be pre-tensioned radially outwards from a working state into an open position, whereby in the working state the snap ring (72) presses the bearing (68) radially inwards, in the open position the snap ring (72) is brought into a position that allows the bearing (68) to be inserted for installation or pulled out for removal, and a section of the snap ring (72), including the radially outer edge (80), is arranged in the groove (96) formed by the rack housing (70), the groove (96) providing space for the eyelet section (90, 92) and for the bending of the snap ring (72) during the opening process. [2] Vehicle steering assembly according to claim 1, wherein the eyelet section (90, 92) is a first eyelet section (90) and the snap ring (72) further comprises a second eyelet section (92). [3] Vehicle steering assembly according to claim 1, wherein the snap ring (72) extends from a first end (74) to a second end (76) to define a length of the snap ring (72). [4] Vehicle steering assembly according to claim 1, wherein the snap ring (72) extends from a first side (82) to a second side (84) to define a thickness of the snap ring (72). [5] Vehicle steering assembly according to claim 4, wherein the chamfered section (86) of the snap ring (72) is located on the second side (84) of the snap ring (72).

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