Steering column energy absorbing rake lock

A position lock for a steering column assembly is provided. The position lock includes an outer cam. Also included is an inner cam defining a slotted aperture to receive a rake bolt operatively coupled to the outer cam, the slotted aperture facilitating shuttling movement of the rake bolt therein. Further included is a tooth lock operatively coupled to the inner cam, the tooth lock rotatable between an unlocked position and a locked position. Yet further included is a pin extending through the inner cam and operatively coupled to the outer cam, and rotation of the outer cam facilitates movement of the tooth lock out of engagement with the rake lock tooth wall when rotating between the locked position and the unlocked position.

FIELD OF THE INVENTION

The following description relates to steering columns for motor vehicles and, more specifically, to a rake lock mechanism for a steering column.

BACKGROUND

Some known steering columns for motor vehicles are provided with mechanisms for adjusting the steering column position by an operator of the motor vehicle. Available adjustments typically include a telescoping adjustment in which the steering column is extended toward the operator or retracted away from the operator, and a tilt or rake adjustment in which an angular position of the steering column is changed relative to the operator.

In some known systems, rake is adjusted by releasing an adjustment lever from a secured position, which then allows for rotation of the steering column about a pivot, typically located at an end of the steering column opposite that of the of the steering wheel. Returning the adjustment lever to the secured position retains the steering column in a desired set position about the pivot.

However, some traditional locks for steering columns may provide inadequate load handling capabilities for preventing upward steering column displacements in the event of a vehicle collision. Some prior attempts to address this issue have sought use of interlocking teeth to provide the required vertical stability. Unfortunately, however, many configurations that employ interlocking teeth to provide for a positive lock, while providing for selective engagement and disengagement of the teeth for alternating adjustment and locking of the steering column, encounter practical difficulties. For example, one source of dissatisfaction with such locking mechanisms is that the need to interlock the teeth of one component with the teeth of another may limit the available lock positions to a predefined finite set of positions. This issue provides a motivation toward decreasing the size of each of the teeth so as to decrease the incremental difference from one position to the next, providing for finer adjustments. Unfortunately, smaller teeth can result in decreased position assurance and loss of tactile sensations normally associated with the failure to securely seat the interlocking teeth. Other proposed solutions involve the use of frictions locks, which may provide more fine adjustments, but may sacrifice reliability, being susceptible to unintended releases (e.g., sliding adjustments, creep) under some loads.

Further, in a vehicle impact event, the steering column is configured to absorb energy of the impact to prevent or reduce injury to the operator due to collision with the steering wheel. In doing so, it is desired to further lock the rake position of the steering column to allow controlled energy absorption in such situations. In some steering column designs, during a collapse cycle, the column is designed to disengage the shaft and jacket assembly from the column mounting bracket. This allows the shaft and jacket assembly to shuttle forward in a vehicle, which allows the column to unclamp to facilitate internal collapse. At this point, rake lock needs to be maintained or re-established.

Accordingly, it is desirable to provide an energy absorbing rake lock assembly configured to establish rake lock during an impact event and to selectively fix and adjust a position of a steering column with improved fineness in the availability of adjustment positions and with improved reliability and security.

SUMMARY OF THE INVENTION

In one exemplary embodiment of the present invention, a position lock for a steering column assembly is provided. The position lock includes an outer cam. Also included is an inner cam defining a slotted aperture to receive a rake bolt operatively coupled to the outer cam, the slotted aperture facilitating shuttling movement of the rake bolt therein. Further included is a tooth lock operatively coupled to the inner cam, the tooth lock rotatable between an unlocked position and a locked position. Yet further included is a pin extending through the inner cam and operatively coupled to the outer cam, and rotation of the outer cam facilitates movement of the tooth lock out of engagement with the rake lock tooth wall when rotating between the locked position and the unlocked position.

In another exemplary embodiment of the present invention, a position lock for a steering column assembly is provided. The position lock includes an outer cam. Also included is an inner cam defining an aperture to receive a rake bolt operatively coupled to the outer cam, the aperture sized to correspond to an outer surface of the rake bolt. Further included is a tooth lock operatively coupled to the inner cam, the tooth lock rotatable between an unlocked position and a locked position. Yet further included is a pin extending through the inner cam and operatively coupled to the outer cam, the outer cam causing movement of the tooth lock out of engagement with the rake lock tooth wall when rotating between the locked position and the unlocked position. Also included is a lower jacket defining a slot to receive the rake bolt.

In yet another exemplary embodiment of the present invention, a steering column assembly is provided and includes a steering column. Also included is a rake lock bracket coupled to the steering column. Further included is a position lock. The position lock includes an outer cam. The position lock also includes an inner cam defining a slotted aperture to receive a rake bolt operatively coupled to the outer cam, the slotted aperture facilitating shuttling movement of the rake bolt therein. The position lock further includes a tooth lock operatively coupled to the inner cam, the tooth lock rotatable between an unlocked position and a locked position. The position lock yet further includes a pin extending through the inner cam and operatively coupled to the outer cam, and rotation of the outer cam causing movement of the tooth lock out of engagement with the rake lock tooth wall when rotating between the locked position and the unlocked position.

DETAILED DESCRIPTION

During typical usage, an eccentric cam is unlocked via feature(s) on a rake lever and or feature(s) on the rake bolt, to allow for rake adjustment of a steering column. Once the desired rake position of the steering column is achieved, the steering column may be relocked via the rake lever. If the lever is in the locked position, the eccentric cam rests against a column mounting tooth configuration, therefore maintaining a constant locked condition.

During a collapse cycle event, the eccentric tooth maintains its locked position while allowing the rake lever and bolt, as well as the jacket assembly to shuttle forward, therefore releasing column clamp pressure. This described shuttling event is facilitated by means of a cylindrical boss feature on the eccentric mounting plate to which the eccentric cam pivots. The boss has a slot at or near center, of which, allows the rake bolt to pass through and allows for shuttling of the rake bolt during the collapse event. These components may also be configured so the boss resides on the eccentric cam, with a slot at or near center of the boss, and the mating plate would have a round hole in which the eccentric cam boss will mate. As a result, the eccentric toothed cam is configured to wind up and create binding/locking in the rake direction. In addition, reaction feature(s) may be added to existing component(s) and or additional component(s) to further provide added binding/locking.

Referring now to the Figures, where the invention will be described with reference to specific embodiments, without limiting same,FIGS. 1A, 1B and 2illustrate an exemplary steering column assembly100. As shown inFIGS. 1A and 1B, an exemplary steering column assembly100of a vehicle (not shown) comprises a steering column lock arm184for selectively resisting or facilitating raking movement of a steering column116within an adjustment range defined by a position lock102. When the steering column lock arm184is positioned so as to place the position lock102in a locking mode, the steering column116is inhibited from being adjusted. Accordingly, the steering column116is relatively fixed, positionally, with respect to the vehicle. When the steering column lock arm184is positioned so as to place the position lock102in an adjustment mode, adjustments to the positioning of the steering column116are facilitated. Accordingly, the steering column116is relatively may be positionally adjusted relative to the vehicle. Once the steering column116occupies a desirable position, the steering column lock arm184may be re-positioned so as to return the position lock102to the locking mode.

Position lock102is configured for selectively resisting or facilitating raking adjustment of a steering column116of a vehicle and includes a rake lock bracket104. In an exemplary embodiment, the rake lock bracket104is fixed to a structure of the vehicle (not shown) and disposed adjacent to the steering column116, along a raking direction118of the steering column116. As shown inFIGS. 1 and 2, an exemplary rake lock bracket104has a rake lock tooth wall108that bounds a control slot178(FIG. 1A) and that defines a plurality of rake lock teeth112. The rake lock tooth wall108with its plurality of rake lock teeth112provides a stationary structure against which a cooperating member (e.g., a locking tooth114) may be engaged so as to lock the cooperating member to the stationary structure. It should be appreciated that locking surface features other than teeth (e.g., a rough or tacky surface) may be employed so as to provide a stationary structure against which a cooperating member may be engaged so as to lock the cooperating member to the stationary structure.

A tooth lock114is supported for rotation about a tooth lock rotation axis120, and a driver122is supported for rotation about a driver rotation axis124. In an exemplary embodiment, both the tooth lock rotation axis120and the driver rotation axis124correspond to the longitudinal axis of a rake lock control shaft or bolt136, which is coupled to the steering column lock arm184. The steering column lock arm184is coupled to the rake lock control shaft136such that steering column lock arm184facilitates application of a torque upon the rake lock control shaft136in either a locking direction134or an adjustment direction170(seeFIG. 1A).

In an exemplary embodiment, an outer cam110operates in conjunction with the steering column lock arm184so as to limit the absolute range of rotation of the rake lock control shaft136so as to prevent application of excessive loads upon the tooth lock114or other components of the position lock102.

An inner cam176may be used in connection with the outer cam110to limit the absolute range of rotation of the rake lock control shaft136. For example, a pin150may be pressed into a slot152formed in outer cam110, and pin150may then extend through a slot154formed in inner cam176to interact with tooth lock114. As illustrated, as lock arm184rotates in the adjustment direction, pin150engages a first tooth lock projection156to rotate tooth lock114away from engagement with tooth wall108. Similarly, as lock arm184rotates in the locking direction134, pin150is engageable with a second tooth lock projection158to rotate tooth lock114into engagement with tooth wall108. Alternatively, or in combination with engagement of the pin150and second tooth lock projection158, the pin may allow a spring load to rotate with the tooth lock114. Driver122may interact with the tooth lock projections156,158in a similar manner.

In addition, the inner cam176may be used along with the rake lock bracket104to define the range of translational motion of the rake lock control shaft136as well as that of the tooth lock114and the driver122. A spring130is arranged so as to aid in control of the tooth lock114. The tooth lock114is configured for selectively engaging and disengaging from the rake lock tooth wall108and the plurality of rake lock teeth112, in response to rotation of the rake lock control shaft136, so as to selectively resist or facilitate translation of the tooth lock114in the raking direction118.

In an exemplary embodiment, the rake lock control shaft136is translationally fixed to both the steering column116and the tooth lock114such that when the steering column116undergoes raking movement, the rake lock control shaft136and the tooth lock114also undergo raking movement. Accordingly, when the tooth lock114is prevented from undergoing raking movement, the rake lock control shaft136and the steering column116are also prevented from undergoing raking movement. In an exemplary embodiment, the tooth lock114is coupled to the steering column116for movement with the steering column116in a raking direction118, and, as shown inFIG. 1B, the driver122is supported for translation with the tooth lock114.

FIG. 2illustrates portions of an exemplary position lock102in both a locked mode and unlocked mode. As shown inFIG. 2, the tooth lock114is configured for engaging, upon rotation in the locking direction134, at least one tooth of the plurality of rake lock teeth112so as to selectively resist translation of the tooth lock114and the steering column116in the raking direction118.

FIG. 2illustrates portions of an exemplary position lock102in the unlocked mode or adjustment mode. As shown inFIG. 2, the tooth lock114is configured for disengaging, upon rotation in an adjustment direction170, from the at least one tooth of the plurality of rake lock teeth112so as to selectively facilitate translation of the tooth lock114and the steering column116in the raking direction118. In addition, a driver control arm172of driver122contacts first projection156on tooth lock114, thereby causing a toothed peripheral edge140on tooth lock114to disengage from the plurality of rake lock teeth112on rake lock bracket104.

In the exemplary embodiment, the inner cam176includes a cylindrical boss160and a slotted bolt opening162to facilitate forward translation of rake bolt136therein. Tooth lock114is positioned over and rotates about the cylindrical boss160such that tooth lock114may engage tooth wall108and maintain engagement therewith as rake bolt136shuttles or translates forward in slotted bolt opening162. For example, during a crash event, lever184, bolt136, outer cam110, and pin150move forward in the direction of arrow164(FIG. 1B), which allows shuttling thereof and release of the column clamping device104to release so an energy absorption mechanism (e.g., a roll strap) may take effect. As such, slotted opening162enables rake bolt136to shuttle without interrupting the engagement between tooth lock114and tooth wall108.

The clamping device104surfaces that engage the steering column116may be angled along the clamp path. Such angling may be employed to facilitate the start of collapse, provide clamp pressure relief, and/or cushion impact loads at a travel stop. It is to be appreciated that all or fewer of the clamp surfaces may be angled.

FIG. 3illustrates an alternate position lock202that is similar to the position lock102except inner cam176includes a post204to receive the spring130. In addition, the inner cam176and tooth lock114include respective apertures206and208to receive a portion of the spring130, as shown inFIG. 3.

FIG. 4illustrates an alternate position lock302that is similar to the position lock102except inner cam176includes a post304to receive the spring130. In addition, the inner cam176and tooth lock114include respective apertures306and308to receive a portion of the spring130, as shown inFIGS. 4A and 4B.

FIG. 5illustrates an alternate position lock402that is similar to the position lock102except it includes an inner cam476, a tooth lock414, and a pin450. Inner cam476includes a cylindrical boss460that receives a flange480of tooth lock414to facilitate rotation of tooth lock414therein. Pin450includes a first projection452and a second projection454. First projection452is positioned within a slot456formed in outer cam110, and second projection454is positioned within a slot458formed in tooth lock414. As such, rotation of outer cam110engages first projection452, which rotates pin450and causes rotation of tooth lock414into and out of engagement with tooth wall108.

FIG. 6illustrates an alternate position lock502that is similar to the position lock102except it includes an inner cam576, a tooth lock514, and a pin550. Inner cam576includes a cylindrical bore560that receives the spring130and a flange580of tooth lock514to facilitate rotation of tooth lock514therein. Pin550includes a first projection552and a second projection554. First projection552is positioned within a slot556formed in outer cam110, and second projection554is positioned within a slot558formed in tooth lock514. As such, rotation of outer cam110engages first projection552, which rotates pin550and causes rotation of tooth lock514into and out of engagement with tooth wall108.

FIG. 7illustrates an alternate position lock602that is similar to the position lock102and similar reference numerals are employed for corresponding elements. The inner cam176of position lock602includes a slot bolt opening662that is not slotted as is the case with position lock102. Rather, the slot bolt opening662is dimensioned to correspond to the outer dimension of rake bolt136. Such dimensioning results in a tight, fitted relationship between the inner cam176and the rake bolt136. Rather than having the rake bolt136move forward relative to the jacket during shuttling of the jacket, the rake bolt does not move forward relative to the jacket. In the illustrated embodiment, the rake bolt moves with the jacket due to at least one slot650defined by the lower jacket, the rake bolt136extending through the slot(s)650. This assembly allows forward motion of the lower jacket during an energy absorption event, without requiring the rake bolt136to move forward. In this embodiment, the rake bolt136remains stationary in the fore-aft direction and is fully piloted by the inner cam176.

The systems and methods described herein may function within small package environments with a limited number of engaged teeth. Further, design options also exist with a stationary bolt axis among other moving components to engage (e.g., lower jacket199).