Dual taper steering column lock bolt

The invention provides a locking pin for a steering column lock assembly. The locking pin includes a dual taper defined by the first and second truncated cone portions. The first truncated cone portion narrows at a first angle and the second truncated cone portion narrows at a second angle, wherein the first and second angles are different from one another. The second angle can be less than the first angle. The dual taper of the locking pin reduces the likelihood that extreme torsion will not induce camming forces urging the locking pin out of engagement with a locking plate connected to the steering shaft.

TECHNICAL FIELD

The invention relates to a lock for a steering column of a vehicle to prevent the steering wheel from being turned.

BACKGROUND OF THE INVENTION

Steering columns in vehicles normally include a locking mechanism to prevent turning of the steering wheel when the ignition is off and the key is removed. As shown in U.S. Pat. No. 4,258,560, a steering column lock can include a locking plate connected to an upper end of a steering shaft. The steering shaft connects the steering wheel with the steerable tires of the vehicle. The locking plate extends radially from the steering shaft and defines one or more apertures for receiving a locking pin. When the locking pin is inserted in the aperture, the steering shaft is locked.

The locking pin can define a tapered surface that engages the aperture of the locking plate. The tapered surface can enhance removal of the pin with respect to the locking plate, to enhance and facilitate unlocking of the steering column. For example, the edge of the aperture can slide along the tapered surface of the pin during insertion and removal of the pin, preventing binding between the two parts. However, during unauthorized starting of the vehicle, the steering shaft can be subjected to extreme torsional loading. During the severe torsion that can be generated during an attempted theft of the vehicle, the tapered surface of the locking pin can act as a cam follower surface and the surface of the aperture of the locking plate can act as a cam. In other words, the locking plate can drive the locking pin out of engagement with the aperture when a theft of the vehicle is attempted, making the theft easier.

SUMMARY OF THE INVENTION

The present invention provides a steering column lock assembly including a steering shaft defining an aperture and a locking pin insertable in the aperture and having first and second tapered portions for limiting cam-cam follower cooperation between the locking pin and the aperture. The tapered surfaces define first and second truncated cone portions having different angles. The locking pin can include a first truncated cone portion narrowing from a first end at a first angle to a second end. A second truncated cone portion can extend from the second end and narrow at a second angle to a third end. The first and second angles are different with respect to one another. The second angle is less than the first angle. The first angle can define a tapered surface to enhance unlocking of the steering column. For example, the first truncated cone portion can make it easier to unlock the steering column by sliding against a locking plate in the steering column. The second angle can define a tapered surface that reduces the likelihood that extreme torsional loading will drive the locking pin out of engagement with a locking aperture defined by the steering shaft. For example, the sliding movement described above is reduced by the second truncated cone portion to deter vehicle theft. The two cone portions cooperate to facilitate enhanced removal of the locking pin during authorized vehicle start-up, while simultaneously restricting movement of the pin during unauthorized vehicle start-up.

DESCRIPTION OF THE PREFERRED EMBODIMENT

A plurality of different embodiments of the invention are shown in the Figures of the application. Similar features are shown in the various embodiments of the invention. Similar features have been numbered with a common two-digit reference numeral and have been differentiated by a third digit placed before the two common digits. Also, to enhance consistency, features in any particular drawing share the same third digit designation even if the feature is shown in less than all embodiments. Similar features are structured similarly, operate similarly, and/or have the same function unless otherwise indicated by the drawings or this specification. Furthermore, particular features of one embodiment can replace corresponding features in another embodiment unless otherwise indicated by the drawings or this specification.

Referring toFIG. 1, a vehicle10is shown including a steering column assembly12mounted in the forward passenger compartment. The steering column assembly12extends through the firewall of the vehicle engine compartment and includes a cylindrical upper jacket14secured by a bracket assembly16to support structure of the vehicle10. A shift bowl18is supported for limited rotational movement on the upper end of the jacket14and may be turned by the vehicle operator through a selector lever20. A generally cylindrical housing22is secured to the upper jacket14and located between the shift bowl18and steering wheel26. The housing22can also support a lever27for operating turn signals or headlamps of the vehicle10. A steering wheel26is drivingly connected to a rotatable steering shaft28(best shown inFIGS. 2 and 3). The steering wheel26engages the shaft28at a hub29. The shaft28extends axially within the steering column assembly12to operably connect the steering wheel26with respect to the wheels of the vehicle through a conventional steering gear and linkage.

Referring now toFIGS. 2 and 3, the steering column assembly12according to the invention includes a steering shaft28defining at least one receiving portion38and a locking pin40. The receiving portion38can be an aperture or can be a notch. The locking pin40is selectively insertable in the receiving portion38. The locking pin40is moveable between at least two positions. In a first position corresponding to a locked position, the locking pin40is insertable in the receiving portion to prevent rotation of the steering shaft28. In a second position corresponding to an unlocked position, the locking pin40is disengaged with respect to the receiving portion38and the steering shaft28is rotatable.

The steering shaft28is shown mounted for rotation in a first longitudinal recess32defined by the steering column housing22. The housing22also defines a second recess34for receiving the locking pin40. The locking pin40can be slidably mounted within the second recess34of the steering column housing22. The second recess34can extend parallel to the first recess32and be offset with respect to the first recess32. In an alternative embodiment, the second recess could extend radially from the first recess.

The housing22is also shown supporting a locking cylinder24. The locking cylinder24can receive a key25. The key25can be inserted in the locking cylinder24and rotated to move a gear train30and slide the locking pin40relative to the housing22within the second recess34. For example, when the key25is removed from the locking cylinder24, the locking pin40is inserted in the receiving portion38.

A plate member36can be immovably associated with respect to the steering shaft28. The receiving portion38is shown defined by the plate member36, however, the receiving portion38could be defined by the steering shaft28. The plate member36is rotatably locked with respect to the steering shaft28such that the plate member36rotates in response to rotation of a steering wheel26and insertion of the locking pin40in the receiving portion38defined by the plate member36prevents rotation of the steering shaft28and steering wheel26.

The plate member36rotates the receiving portion38in response to rotation of the shaft28. During rotation of the plate member36, the receiving portion38intermittently communicates with the second recess34. The locking pin40can be inserted with respect to the receiving portion38when the receiving portion38is in communication with the recess34. As shown inFIGS. 2 and 3, the receiving portion38can extend in parallel relation to the steering shaft28.

The locking pin40includes a first truncated cone portion42narrowing from a first end44at a first angle46to a second end48. The locking pin40also includes a second truncated cone portion50extending from the second end48and narrowing from the second end48at a second angle52to a third end54. The first and second truncated cone portions42,50can extend concentrically with respect to one another. The first and second angles46,52are different. The second angle52can be less than the first angle46. By way of example and not limitation, the second angle52can be one-half of the first angle46. For example, the second angle52can be four degrees and the first angle46can be eight degrees.

The first and second truncated cone portions42,50can be inserted in the receiving portion38. The receiving portion38and locking pin40can cooperate in cam-cam follower relationship. For example, the first truncated cone portion42can be angled to enhance sliding between the locking pin40and the receiving portion38. Enhanced sliding engagement between the locking pin40and the receiving portion38can be desirable during authorized insertion and removal of the locking pin40with respect to the receiving portion38. For example, the angled surface56of the first truncated cone portion42can guide insertion of the locking pin40with respect to the receiving portion38and alleviate slight misalignments between the two parts. Also, the angled surface56of the first truncated cone portion42can communicate torsion from the receiving portion38to axial force urging the locking pin40out of engagement with the receiving portion during authorized vehicle start-up.

The second cone portion50can be angled to be less likely to cooperate in cam-cam follower relationship with the receiving portion38than the first truncated cone portion42. For example, the second truncated cone portion50is flatter than the first truncated cone portion42to reduce the likelihood that torsion will urge the locking pin40out of engagement with the receiving portion38. Extreme torsion can occur during an attempted theft of the vehicle. It has been determined that the present invention reduces by one-half the force urging the bolt40out of the receiving portion38during extreme torsion loading. Specifically, the urging force generated torsion loading.

Referring now toFIG. 4, in a second exemplary embodiment of the invention, a locking pin140includes a first truncated cone portion142narrowing from a first end144at a first angle146to a second end148. The locking pin140also includes a second truncated cone portion150extending from the second end148and narrowing from the second end148at a second angle152to a third end154. The first and second truncated cone portions142,150can extend concentrically with respect to one another. The first and second angles146,152are different. The second angle152can be less than the first angle146. By way of example and not limitation, the second angle152can be one-half of the first angle146. For example, the second angle152can be four degrees and the first angle146can be eight degrees.

The locking pin140can selectively engage a receiving portion138of a steering shaft128. The receiving portion138is defined directing by the steering shaft128, in comparison with the receiving portion38of the first embodiment that is defined by the plate member36that is rotatably locked with respect to the steering shaft28. The receiving portion138extends radially with respect to a longitudinal axis of the steering shaft128. The locking pin140can be disposed in a first recess (not shown) extending radially from the receiving portion138.

The first and second truncated cone portions142,150can be inserted in the receiving portion138. The receiving portion138and locking pin140can cooperate in cam-cam follower relationship. For example, the first truncated cone portion142can be angled to enhance sliding between the locking pin140and the receiving portion138. Enhanced sliding engagement between the locking pin140and the receiving portion138can be desirable during authorized insertion and removal of the locking pin140with respect to the receiving portion138. For example, the angled surface156of the first truncated cone portion142can guide insertion of the locking pin140with respect to the receiving portion138and alleviate slight misalignments between the two parts. Also, the angled surface156of the first truncated cone portion142can communicate torsion from the receiving portion138to axial force urging the locking pin140out of engagement with the receiving portion during authorized vehicle start-up.

The second cone portion150can be angled to be less likely to cooperate in cam-cam follower relationship with the receiving portion138than the first truncated cone portion142. For example, the second truncated cone portion150is flatter than the first truncated cone portion142to reduce the likelihood that torsion will urge the locking pin140out of engagement with the receiving portion138. The second cone portion150can also define a rougher surface finish than the first truncated cone portion142to be less likely to cooperate in cam-cam follower relationship with the receiving portion138than the first truncated cone portion142. For example, the surface finish of the first truncated cone portion142can have a relatively smaller coefficient of friction to facilitate low withdrawal force during normal lock bolt retraction at vehicle start. The force required to withdrawal the dual surface-finish locking pin140at vehicle start could be the same as the force required to withdrawal the single surface-finish locking pin40at vehicle start. On the other hand, the surface finish of the second truncated cone portion150can have a relatively greater coefficient of friction reduce the likelihood of forced cam out of the locking pin140. During forced cam out of the locking pin140on the first cone portion142with the lower friction surface, the cam force urging the locking pin140out of engagement with the receiving portion138is less than the cam force urging the locking pin140out of engagement with the receiving portion138because of the higher friction surface of the second cone portion150.

In the different embodiments, the sliding motion of the lock pin40or the lock pin140can also be accomplished remotely via a cable, or by electromechanical mechanization.