LOCKING MECHANISM FOR LOW-PROFILE ENERGY ABSORBING BELT

Abstract

A locking mechanism for a steering column assembly includes an energy absorption belt having a first plurality of teeth formed thereon. The locking mechanism further includes a toothed plate having a second plurality of teeth formed thereon. The locking mechanism further includes a pair of springs in contact with an outer side of a toothed plate, the pair of springs biasing the toothed plate to a locked position, the locked position being defined by engagement of the second plurality of teeth with the second plurality of teeth. The locking mechanism further includes a pair of cams in contact with an inner side of the toothed plate, wherein rotation of the pair of cams moves the second plurality of teeth out of engagement with the first plurality of teeth to define the unlocked position.

Description

TECHNICAL FIELD The following description relates to vehicle steering systems and, in particular, to a low profile energy absorbing belt locking mechanism. BACKGROUND A vehicle, such as a car, truck, sport utility vehicle, crossover, minivan, watercraft, aircraft, off-road vehicle, recreational vehicle, or other suitable vehicle, includes various steering system schemes, such as steer-by-wire and driver interface steering. These steering systems typically include a steering column for translating steering input into output, which interacts with a steering linkage to ultimately cause the vehicle's wheels (or other elements) to turn. Some steering columns are axially adjustable between positions to provide flexibility in steering wheel positioning and to enable more comfortable driving positions for drivers of different sizes or autonomous driving capability. In addition to providing adjustment capability, axially adjustable steering column assemblies can also include a folding function, providing safety benefits during an energy absorption event. A locking mechanism may be required to hold a movable portion of the steering column assembly in a desired position after axial adjustment. A locking mechanism commonly used in the automotive industry is the so-called telescoping positive locking mechanism. When designing a telescoping positive locking mechanism, care is typically taken to ensure the column locks and unlocks properly. The unlocked state must ensure the full collapsible / axial adjustment range.When locked, the steering column assembly must maintain a fixed collapsible / axial position under normal vehicle operating conditions. However, during a collapsible event, various measures may be implemented to ensure a required collapsible state and / or range of motion within a range of applied load. Some manually adjustable steering column assemblies utilize a telescopic eccentric cam to provide a locked and unlocked telescopic position for the steering column. Such assemblies typically require one or more complex projections on the lever, which is grasped by the driver to respond with a toothed mechanism that interacts with an energy-absorbing belt. Furthermore, most complete assemblies require extensive packaging and face the challenge of meeting OEM space requirements. SUMMARYAccording to one aspect of the disclosure, an axially adjustable steering column includes an upper shroud. The steering column further includes a lower shroud, wherein the upper shroud is axially adjustable relative to the lower shroud. The steering column further includes an adjustment lever. The steering column further includes a locking mechanism, wherein the adjustment lever selectively moves the locking mechanism between a locked position and an unlocked position, wherein the locked position prevents axial adjustment of the upper shroud relative to the lower shroud in both axial directions and the unlocked position allows adjustment of the upper shroud relative to the lower shroud.The locking mechanism includes an energy absorption belt operatively coupled to the upper shroud, the energy absorption belt having a first plurality of teeth formed thereon. The locking mechanism further includes a tooth plate operatively coupled to the lower shroud, the tooth plate having a second plurality of teeth formed thereon. The locking mechanism further includes a clamp bolt operatively coupled to the lever. The locking mechanism further includes a first cam operatively coupled to the clamp bolt, wherein rotation of the adjustment lever causes rotation of the cam, wherein rotation of the cam selectively moves the second plurality of teeth into and out of engagement with the first plurality of teeth to define the locked position and the unlocked position, respectively. According to another aspect of the disclosure, a locking mechanism for a steering column assembly includes an energy absorption belt having a first plurality of teeth formed thereon. The locking mechanism further includes a tooth plate having a second plurality of teeth formed thereon. The locking mechanism further includes a pair of springs in contact with an outer surface of a tooth plate, the pair of springs biasing the tooth plate to a locked position, the locked position being defined by engagement of the second plurality of teeth with the second plurality of teeth. The locking mechanism further includes a pair of cams in contact with an inner surface of the tooth plate, wherein rotation of the pair of cams moves the second plurality of teeth out of engagement with the first plurality of teeth to define the unlocked position. These and other aspects of the present disclosure are disclosed in the following detailed description of the embodiments, the appended claims, and the accompanying figures. BRIEF DESCRIPTION OF THE DRAWINGS The disclosure will best be understood from the following detailed description when read in conjunction with the accompanying drawings. It is emphasized that, in accordance with common practice, the various features of the drawings are not to scale. On the contrary, the dimensions of the various features are arbitrarily expanded or reduced for the sake of clarity. Fig. 1 schematically illustrates a steering system including an adjustable steering column assembly; Fig. 2 is a perspective view of the steering column assembly having an energy absorption locking mechanism; Fig. 3 is a perspective, enlarged view of a portion of Fig. 2 illustrating further aspects of the energy absorption locking mechanism; Fig. 4 is a perspective view of the energy absorption locking mechanism in a locked state; and Fig.5 is a perspective view of the energy absorption locking mechanism in an unlocked state. DETAILED DESCRIPTION The following discussion relates to various embodiments of the disclosure. The disclosed embodiments should not be interpreted or otherwise used as a limitation on the scope of the disclosure, including the claims. Furthermore, one of ordinary skill in the art will understand that the following description has broad application, and the discussion of one embodiment is intended only as an example of that embodiment and does not imply that the scope of the disclosure, including the claims, is limited to that embodiment. Referring now to the drawings, in which the various embodiments are shown and described, without limitation, the figures illustrate embodiments of a steering column assembly that is axially adjustable and includes a locking mechanism that is more compact and less complex than previous locking mechanisms. Axial adjustability may result from relative movement between two or more shrouds that permit axial movement therebetween. For example, a first shroud and a second shroud move in a relative telescopic, sliding, or translational configuration. Referring first to Fig. 1, a steering system 40 for a vehicle according to the principles of the present disclosure is generally illustrated. The vehicle may include any suitable vehicle, such as a car, a truck, a sport utility vehicle, a minivan, a crossover, any other passenger vehicle, any suitable commercial vehicle, or any other suitable vehicle. Furthermore, the principles of the present disclosure may also be applicable to other vehicles, such as aircraft, boats, trains, drones, or other vehicles. The steering system 40 may be configured as a driver interface steering system, an autonomous driving system, or a system that enables both a driver interface and autonomous steering. The steering system includes an input device 42, such as a steering wheel, wherein a driver can mechanically provide steering input by turning the steering wheel. An airbag device 43 may be located on or near the input device 42. A steering column assembly 44 extends along an axis from the input device 42 to an output assembly 46. The output assembly 46 may include a pinion shaft assembly, an I-shaft, a universal joint, steer-by-wire components, or any other features typically located opposite the input device 42. The steering column assembly 44 may include at least two axially adjustable parts, for example, a first shroud 48 and a second shroud 50 that are axially adjustable relative to each other. The first shroud 48 and the second shroud 50 may alternatively be configured as brackets, rails, or other members that allow axial movement therebetween.The axial movement may include sliding, telescopic, translational, and other axial movements. The steering column assembly 44 may include a bracket 51 that at least partially connects the steering column assembly 48 to the vehicle. An adjustable lever 52 may be operatively connected to the first shroud 48, the second shroud 50, or the bracket 51 to enable axial or tilt adjustment of the steering column assembly 44. In some embodiments, the behavior of the adjustable lever 52 is controlled via a control system 300 that includes a CPU unit. In some embodiments, the behavior of the adjustable lever 52 is manually controlled by a driver. The steering column assembly 44 is movable through a range of positions from an extended position to a retracted position. While the second shroud 50 is intended to be axially adjustable, the first shroud 48 is axially adjustable relative to the second shroud 50 to at least partially define the extended and retracted positions of the steering column assembly 44. For example, the first shroud 48 may be referred to as the "upper shroud," and the second shroud 50 may be referred to as the "lower shroud." A steering gear assembly 54 may be connected to the output assembly 46 via a steering gear input shaft 56. The steering gear assembly 54 may be configured as a rack and pinion steering gear, a recirculating ball steering gear, or any other type of steering gear associated with autonomous steering systems and driver interface steering systems. The steering gear assembly 54 may then be connected to a drive axle 58 via an output shaft 60. The output shaft 60 may include a pitman arm and a sector gear or other traditional components. The output shaft 60 is operatively connected to the steering gear assembly 54 such that rotation of the steering gear input shaft 56 causes a reactive movement of the output shaft 60 and causes the drive axle to turn the wheels 22. In other embodiments, the steering column assembly 44 is not directly mechanically connected to the steering gear assembly 54.Such an embodiment can be called a steer-by-wire system. Fig. 2 generally illustrates the adjustable steering column assembly 44 with the lever 52 and a locking mechanism 100. The adjustable lever 52 is partially shown and extends from a free end (not shown) to a connecting end 101 connected to the steering column assembly 44. The locking mechanism 100 includes a cam assembly (not shown) which biases the upper and lower shrouds to an unlocked position upon rotation of the lever 52 to allow telescopic adjustment of the upper shroud 48 relative to the lower shroud 50, and selectively locks the upper and lower shrouds in a fixed position. Referring to Fig. 2 and Fig. 3, the locking mechanism 100 includes an energy absorption belt 102, a tooth plate 104, a pair of mechanical fasteners 106, a pair of springs 108, a clamp bolt 110, a bumper spacer 111, and a pair of cams 112. The energy absorption belt 102 is operatively coupled to the upper shroud 48 by one or more fasteners or via welding. The energy absorption belt 102 includes a first leg 114, a second leg 116, and a curved transition portion (not shown) connecting the first leg 114 and the second leg 116. The first leg 114 is coupled to the upper shroud 48, and the second leg 116 includes a plurality of teeth 120 (see also FIGS. 4 and 5 ) configured to selectively engage a plurality of teeth 122 of the tooth plate 104. The plurality of teeth 120 are formed on an outer side of the second leg 116 of the energy absorption belt 102. In particular, an engaged state of the teeth 120 of the energy absorption belt 102 and the teeth 122 of the tooth plate defines the locked state of the locking mechanism 100 (Fig.4), and a disengaged state of the teeth 120, 122 defines the unlocked position (Fig. 5). In the unlocked position of the locking mechanism 100, the energy absorption belt 102, with the upper shroud 48 to which it is coupled, can move freely axially in the telescopic direction as described above. The tooth plate 104 is operatively coupled to a relatively stationary component of the steering column assembly 44, such as the lower shroud 50. The tooth plate 104 includes a main body portion 124 with a pair of lateral flanges 126 extending from the main body portion 124. A pair of inwardly extending segments 128 extend from the main body portion 124. The plurality of teeth 122 of the tooth plate 104 are formed on an inner side of the main body portion 124 and positioned between the inwardly extending segments 128. The inwardly extending segments 128 are each disposed on opposite sides of the second leg 116 of the energy absorption belt 102. Each of the side flanges 126 defines a corresponding hole 132, 134 sized to receive one of the mechanical fasteners 106. In some embodiments, the mechanical fasteners 106 are shoulder bolts or the like. Regardless of the particular type of mechanical fasteners 106 used, each fastener 106 includes a head portion 136 and a shank portion 138. The shank portion 138 extends through the holes 132, 134, and the head portion 136 is located on an outer side 140 of the tooth plate 104. Each mechanical fastener 106 has one of the springs 108 surrounding the portion of the shank portion 138 disposed between the head portion 136 and the outer side 140 of the tooth plate 104. The springs 108 may be coil springs or any other suitable type of resilient member. The springs 108 urge the toothed plate 104 toward the second leg 116 of the energy absorption belt 102 so that the teeth 122 of the toothed plate 104 fully engage the teeth 120 of the energy absorption belt 102. Therefore, the spring force and pressure of the springs 108 must be considered to ensure secure engagement of the teeth 120, 122 as the default position of the locking mechanism 100. The use of symmetrically arranged springs 108 and mechanical fasteners 106 provides substantially balanced forces to move the toothed plate 104 more smoothly along the shaft portions 138 of the fasteners 106 during movement between the locked position and the unlocked position. This smooth and balanced movement promotes secure engagement and disengagement of the teeth 120, 122 during operation. The clamp bolt 110 is operatively connected to the terminal end 101 of the lever 52 and is rotatable therewith. Therefore, when the lever 52 is rotated from a locked position to an unlocked position, the clamp bolt 110 rotates accordingly. The bumper spacer 111 is operatively connected to or integrally formed with an outer surface of the clamp bolt 110. The bumper spacer 111 may be formed of a different material than the clamp bolt 110. Each of the pair of cams 112 is positioned at respective ends of the bumper spacer 111. Each of the cams 112 is aligned with one of the pair of inwardly extending segments 128.The cams 112 are rotationally fixed to the clamping bolt 110 such that the rotational orientation of the cams 112 results in the tooth plate 104 being in the locked state of the locking mechanism 100 when the lever 52 is in the locked position, and in the tooth plate 104 being biased into the unlocked state of the locking mechanism 100 by contact with the inwardly extending segments 128 when the lever 52 is in the unlocked position. Referring to Fig. 4 and Fig. 5, the locking mechanism 100 is shown in a locked state (Fig. 4) and an unlocked state (Fig. 5). Specifically, in the locked state, the plurality of teeth 120 of the energy absorbing belt 102 meshingly engages the plurality of teeth 122 of the toothed plate 104. The engagement of the teeth 120, 122 prevents movement of the energy absorbing belt 102—and therefore the upper shroud 48—in either direction (i.e., fore and aft) parallel to the longitudinal axis of the steering column assembly 44 because the toothed plate 104 is fixed to a stationary structure, such as the lower shroud 50. The cams 112 each include a biasing portion 142 arranged to move the tooth plate 104 outwardly (downward in the views of Figs. 2 to 5) in the unlocked position and to allow inward movement (upward in the views of Figs. 2 to 5) in the unlocked position under the spring force of the springs 108. In operation, when the lever 52 is in the locked position, the cam 112 is oriented so that the tooth plate 104 can be sufficiently biased by the springs 108 to cause the teeth 120 of the belt 102 to engage the teeth 122 of the tooth plate 104. When the lever 52 is rotated to the unlocked position, the cam 112 is rotated to allow the tooth plate 104 to move outward to provide a gap between teeth 120 and teeth 122, thereby unlocking the steering column assembly 44. The above-described embodiments, implementations, and aspects have been described to facilitate a simple understanding of the present disclosure and do not limit the present disclosure. Rather, the disclosure is intended to cover various modifications and equivalent arrangements included within the scope of the appended claims, which scope is to be interpreted as broadly as possible to include all modifications and equivalent structures permitted by law.

Claims

[1] Axially adjustable steering column, comprising: an upper casing; a lower shroud, the upper shroud being axially adjustable relative to the lower shroud; an adjustment lever; and a locking mechanism, wherein the adjustment lever selectively moves the locking mechanism between a locked position and an unlocked position, the locked position preventing axial adjustment of the upper shroud relative to the lower shroud in both axial directions and the unlocked position allowing adjustment of the upper shroud relative to the lower shroud, the locking mechanism comprising: an energy absorption belt operatively coupled to the upper shroud, the energy absorption belt having a first plurality of teeth formed thereon; a tooth plate operatively coupled to the lower shell, the tooth plate having a second plurality of teeth formed thereon; a clamping bolt operatively coupled to the lever; and a first cam operatively coupled to the clamp bolt, wherein rotation of the adjustment lever causes rotation of the cam, wherein rotation of the cam selectively moves the second plurality of teeth into and out of engagement with the first plurality of teeth to define the locked position and the unlocked position, respectively. [2] An axially adjustable steering column according to claim 1, wherein the energy absorption belt comprises: a first leg; and a second leg, wherein the first plurality of teeth are formed on an outer side of the second leg. [3] An axially adjustable steering column according to claim 2, wherein the clamping bolt extends between the first leg and the second leg of the energy absorption belt. [4] An axially adjustable steering column according to claim 2, wherein the tooth plate comprises: a main body section; a pair of side flanges extending from the main body portion; and a pair of inwardly extending segments extending from the main body portion, wherein the second plurality of teeth are formed on an inner side of the main body portion and positioned between the radially inwardly extending segments. [5] An axially adjustable steering column according to claim 4, wherein the inwardly extending segments are each arranged on opposite sides of the second leg of the energy absorption belt. [6] An axially adjustable steering column according to claim 4, further comprising: a pair of mechanical fasteners, each of the pair of mechanical fasteners extending through a respective hole defined by each of the pair of lateral flanges of the tooth plate; and a pair of springs, each of the springs being disposed on a shaft portion of one of the pair of mechanical fasteners, the pair of springs being in contact with an outer surface of the tooth plate to bias the tooth plate into the locked position of the locking mechanism. [7] An axially adjustable steering column according to claim 6, wherein each of the pair of springs is disposed between the outer side of the tooth plate and a head portion of the mechanical fasteners. [8] An axially adjustable steering column as claimed in claim 6, wherein the first cam is aligned with one of the pair of inwardly extending segments of the tooth plate, further comprising a second cam operatively coupled to the clamp bolt and aligned with the other of the pair of inwardly extending segments. [9] An axially adjustable steering column according to claim 8, wherein the first cam and the second cam are rotatably aligned to allow the tooth plate to be in the locked position of the locking mechanism and to move the tooth plate to the unlocked position of the locking mechanism by contacting the pair of inwardly extending segments to overcome a force of the pair of springs. [10] Locking mechanism for a steering column assembly, comprising: an energy absorption belt having a first plurality of teeth formed thereon; a tooth plate having a second plurality of teeth formed thereon; a pair of springs in contact with an outer surface of a tooth plate, the pair of springs biasing the tooth plate into a locked position, the locked position being defined by engagement of the second plurality of teeth with the second plurality of teeth; and a pair of cams in contact with an inner surface of the tooth plate, wherein rotation of the pair of cams moves the second plurality of teeth out of engagement with the first plurality of teeth to define the unlocked position. [11] The locking mechanism of claim 10, wherein the energy absorption belt comprises: a first leg; and a second leg, wherein the first plurality of teeth are formed on an outer side of the second leg. [12] The locking mechanism of claim 11, wherein the tooth plate comprises: a main body section; a pair of side flanges extending from the main body portion; and a pair of inwardly extending segments extending from the main body portion, wherein the second plurality of teeth are formed on an inner side of the main body portion and positioned between the radially inwardly extending segments. [13] The locking mechanism of claim 12, wherein the inwardly extending segments are each disposed on opposite sides of the second leg of the energy absorption belt. [14] The locking mechanism of claim 12, further comprising a pair of mechanical fasteners, each of the pair of mechanical fasteners extending through a respective hole defined by each of the pair of lateral flanges of the tooth plate, and each of the springs being disposed on a shaft portion of one of the pair of mechanical fasteners, the pair of springs being in contact with an outer surface of the tooth plate to bias the tooth plate into the locked position of the locking mechanism. [15] The locking mechanism of claim 14, wherein each of the pair of springs is disposed between the outer surface of the tooth plate and a head portion of the mechanical fasteners. [16] The locking mechanism of claim 12, wherein one of the pair of cams is aligned with one of the pair of inwardly extending segments of the tooth plate, the other of the pair of cams being aligned with the other of the pair of inwardly extending segments. [17] The locking mechanism of claim 16, wherein the pair of cams are rotatably aligned to allow the tooth plate to be in the locked position of the locking mechanism and to move the tooth plate to the unlocked position of the locking mechanism by contacting the pair of inwardly extending segments to overcome a force of the pair of springs.

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