GB2346354A

GB2346354A - Steering column lock

Info

Publication number: GB2346354A
Application number: GB0001966A
Authority: GB
Inventors: Toshiharu Shiramizu
Original assignee: Tokai Rika Co Ltd
Current assignee: Tokai Rika Co Ltd
Priority date: 1999-02-02
Filing date: 2000-01-31
Publication date: 2000-08-09
Anticipated expiration: 2020-01-31
Also published as: JP2000225922A; GB0001966D0; JP3688494B2; GB2346354B

Abstract

A locking device, which locks a steering shaft (70) for vehicles, has a housing (12), a key cylinder (13), and a cam shaft (14). A plate (45) extends between an anti-theft bolt (42) and a notch (41). A spring (43) is located in the notch. When the front portion of the housing (12) is broken away at groove 12a by a thief, the plate (45) is also removed from the device. The anti-theft bolt is moved by the spring (43) and engages with the notch (41), which prevents the cam shaft (14) from rotating. The anti-theft bolt may be provided in the camshaft with the notch in the housing (see figure 5).

Description

STEERING WHEEL LOCKING DEVICE BACKGROUND OF THE INVENTION The present invention relates to a steering wheel locking device that locks a steering shaft against rotation when a key rotor is at a locking position.

A typical steering wheel locking device for vehicles has a housing, a key cylinder and a key rotor. The key cylinder is housed in the housing and accommodates the key rotor. The key rotor is rotated by a key. When the key rotor is moved to a locked position, and is removed from the key rotor, a bolt engages with a steering shaft. The bolt locks the steering shaft against rotation.

The steering wheel locking device also includes a camshaft. The cam of the camshaft rotates integrally with the key rotor. When the key rotor is rotated to one of a plurality of actuation positions, the cam moves the bolt to disengage the lock bar from the steering shaft. The actuation positions of the key rotor include an ACC position for actuating electric accessories, an ON position for running the engine, and an ST position for starting the engine. As the bolt is disengaged from the steering shaft, the steering shaft is unlocked. When rotated to the ST position, the camshaft actuates an ignition switch.

The steering shaft cannot be rotated if a wrong key is inserted into the key cylinder. In other words, the steering wheel cannot be manipulated if a wrong key is inserted. Also, a wrong key cannot actuate the ignition switch. The device therefore deters car theft.

However, if the key cylinder is removed from the housing, for example, by breaking the housing, the camshaft is exposed. This permits the camshaft to be rotated, for example, with pliers. Therefore, a thief thus can unlock the steering wheel.

Japanese Unexamined Patent Publication No. 8-104202 discloses a steering wheel locking device 90 that limits rotation of a camshaft 100. As shown in Fig. 6, the device 90 includes the camshaft 100, a stopper 101, a housing 102, a key cylinder 104 and a key rotor 110. The key rotor 110 is fitted in the key cylinder 104. The stopper 101 is accommodated in the housing 102 and is slidable in the axial direction of the housing 102. A spring 103 urges the stopper 101 toward the key cylinder 104, which is housed in the housing 102. The key cylinder 104 has a projection 104a.

The projection 104a contacts the stopper 101 and prevents the stopper 101 from moving axially. The camshaft 100 has a disk 108, which rotates integrally with the camshaft 100. A notch 107 is formed in the disk 108.

An anti-theft bolt 105 is accommodated in the housing 102. The anti-theft bolt 105 moves in the radial direction of the housing 102. A spring 106 urges the anti-theft bolt 105 to engage the notch 107. When the stopper 101 is at the position shown in Fig. 6, that is, when the housing 102 is not broken and the key cylinder 104 is at a predetermined position, the anti-theft bolt 105 does not engage the notch 107.

Fig. 7 shows a state of the device 90 where the housing 102 is broken and the key cylinder 104 is removed. In this state, the stopper 101 is separated from the anti-theft bolt 105 by the spring 103, which permits the anti-theft bolt 105 to be moved by the spring 106. The anti-theft bolt 105 then engages with the notch 107. The anti-theft bolt 105 prevents the disk 108 and the camshaft 100 from rotating. A lock piece 109 is located between the anti-theft bolt 105 and the spring 103. When the bolt anti-theft bolt 105 engages the notch 107, the spring 103 moves the lock piece 109 beneath the anti-theft bolt 105. The lock piece 109 prevents the anti-theft bolt 105 from disengaging from the notch 107.

The steering wheel locking device 90 includes a great number of parts including the stopper 101, the anti-theft bolt 105, the lock piece 109 and the springs 103,106. The manufacture of the device 90 is therefore costly. Further, the stopper 101 extends in the axial direction of the housing 102, which increases the axial length of the housing 102.

The size of the device 90 is increased, accordingly.

SUMMARY OF THE INVENTION Accordingly, it is a first objective of the present invention to provide an inexpensive, simple steering wheel locking device that prevents a camshaft in a housing from being rotated when a key cylinder is removed from the housing, A second objective of the present invention is to reduce the size of a steering wheel locking device.

To achieve the above objective, the present invention provides a locking device for locking a steering shaft for a vehicle. The locking device includes a housing. The housing has a proximal portion, which is attached to the vehicle, and a distal portion, which extends from the proximal portion. A key cylinder is supported by the proximal portion of the housing. The key cylinder has a key rotor, which is rotated by a key. A cam shaft is rotatably supported by the distal portion of the housing. The cam shaft is integrally connected to the key rotor. The cam shaft has a cam. A locking member is moved by the cam. The cam causes the locking member to lock the steering shaft when the key rotor is rotated to a predetermined lock position. An opening is formed in one of the cam shaft and the proximal portion. An engagement member is movable in the radial direction of the cam shaft to enter the opening. The engagement member is supported by the other of the cam shaft and the proximal portion. The rotation of the cam shaft with respect to the proximal portion is prevented and the locking member locks the cam shaft against the rotation when the engagement member has entered the opening. An urging member urges the engagement member toward the opening. A shutter is attached to the distal portion of the housing or the key cylinder.

The shutter extends between the opening and the engagement member to block the engagement member from entering the opening.

Other aspects and advantages of the invention will become apparent from the following description, taken in conjunction with the accompanying drawings, illustrating by way of example the principles of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS The features of the present invention that are believed to be novel are set forth with particularity in the appended claims. The invention, together with objects and advantages thereof, is best understood by reference to the following description of the presently preferred embodiments together with the accompanying drawings in which: Fig. 1 is a cross-sectional view illustrating a steering wheel locking device according to a first embodiment of the present invention; Fig. 2 is a cross-sectional view like Fig. 1 after the key has been rotated ; Fig. 3 is a cross-sectional view taken along line 3-3 of Fig. 1; Fig. 4 is a cross-sectional view showing the device of Fig. 1 wherein the housing is broken away; Fig. 5 is a cross-sectional view illustrating a steering wheel locking device according to a second embodiment of the present invention; Fig. 6 is a cross-sectional view illustrating a prior art steering wheel locking device; and Fig. 7 is a cross-sectional view showing the device of Fig. 6 when the housing is broken away and the key cylinder is removed.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A steering wheel locking device 11 for a vehicle according to a first embodiment of the present invention will now be described with reference to Figs. 1 to 4.

Fig. 1 is a cross-sectional view illustrating the device 11. The side where a key hole 33 is located will be referred to as the front side of the device 11 and the opposite side will be referred to the rear side of the device 11. The key hole 33 receives a key K.

The device 11 includes a housing 12, a key cylinder 13, a camshaft 14, a coupler 15, a bolt 16, a coil spring 18 and a lid 19.

The housing 12 includes a cup-shaped main casing 20 and a sub-casing 21, which is attached to the main casing 20.

The sub-casing 21 accommodates the bolt 16. The main casing 20 is a distal portion of the housing 12. The sub-casing 21 is a proximal portion of the casing. A first cylindrical chamber 22 is defined in the rear of the main casing 20 to accommodate the camshaft 14. A second cylindrical chamber 23 is defined in the front of the main casing 20 to accommodate the key cylinder 13. The diameter of the first cylindrical chamber 22 is smaller than that of the second cylindrical chamber 23. A step 24 is defined between the first cylindrical chamber 22 and the second cylindrical chamber 23.

A guide chamber 25, which has a square cross section, is defined in the sub-casing 21. The guide chamber 25 extends in a direction that is perpendicular to the axis of the first chamber 22. The guide chamber 25 communicates with the first chamber 22. One end of the guide chamber 25 communicates with an opening 25a formed in the housing 12.

The other end of the guide chamber 25 is opened to the exterior. When the housing 12 is attached to a steering post (not shown), the guide chamber 25 communicates with the interior of the steering post. A recess 26 is formed in the main sub-casing 21 in the vicinity of the guide chamber 25.

The recess 26 is parallel to the guide chamber 25 and d has a square cross section. The lid 19 covers the opening 25a. as illustrated in Fig. 1, a projection 27 of the lid 19 is fitted to the recess 26.

The key cylinder 13 is housed in the second cylindrical chamber 23. The key cylinder 13 includes a cylindrical case 30 A cap 32 is fitted about the front end of the case 30.

The case 30 is fixed to the wall of the second cylindrical chamber 23. The key hole 33, which is circular, is formed in the cap 32.

A key rotor 31 is supported in the case 30. The key rotor 31 accommodates tumblers (not shown). The tumblers are formed by thin plates. When a correct key K is inserted into the key rotor 31, the serrations of the key K engage with the tumblers, which unlocks the key rotor 31. When inserted in the key rotor 31, the correct key K is initially located at a position for locking the steering wheel (LOCK position). The key K can be rotated to a position for actuating accessories (ACC position) or to a position to start the engine (ST position). The key K is also rotatable from the ST position or ACC position to the LOCK position.

As shown in Figs. 1 and 2, a projection 34 is formed at the rear portion of the key rotor 31. The projection 34 has a square cross section and is received by a hole (not shown) formed in the front portion of the cam shaft 14, which causes the camshaft 14 to rotate integrally with the key rotor 31.

A cam 35 is formed in the rear portion of the camshaft 14. The cam 35 is located in the guide chamber 25. A shaft 37 is formed at the rear end of the cam 35. The shaft 37 is rotatably supported by the rear wall of the guide chamber 25.

A starter switch is located behind the sub-casing 21. The shaft 37 is also inserted in a housing 38 of the starter switch and is coupled to a movable contact (not shown) located in the housing 38.

The coupler 15 is formed like a square frame and is located in the guide chamber 25. The coupler 15 can slide in the longitudinal direction of the guide chamber 25. The coupler 15 includes a large cross section portion 15a and a small cross section portion 15b. The bolt 16 is also accommodated in the guide chamber 25, and the bolt 16 can slide in the longitudinal direction of the guide chamber 25.

A groove 16a is formed in the bolt 16. The small cross section portion 15b is engaged with the groove 16a, which causes the bolt 16 and the coupler 15 to move integrally.

The cam 35 extends through the coupler 15. When rotated, the cam 35 moves the coupler 15 in the guide chamber 25. When the coupler 15 is at the position shown in Fig. 1, the distal end of the bolt 16 extends inside interior of a steering post (not shown) and engages a recess 71 of a steering shaft 70, which locks the steering shaft 70 against rotation.

When the coupler 15 is at a position shown in Fig. 2, the distal end of the bolt 16 is disengaged from the shaft recess 71, which unlocks the steering shaft 70.

A coil spring 18 is located between the large cross section portion 15a and the lid 19 The spring 18 urges the bolt 16 through the coupler 15 in a direction locking the steering shaft 70.

A hole 41 is formed in the projection 27. An engagement member, which is an anti-theft bolt 42 in this embodiment, is located in the hole 41 to be movable in the radial direction of the housing 12. The distal end of the anti-theft bolt 42 extends through a bore 44 formed in the recess 26. An urging member, which is a coil spring 43 in this embodiment, is located between the bottom of the hole 41 and the proximal end of the anti-theft bolt 42. The coil spring 43 urges the anti-theft bolt 42 toward the camshaft 14.

A notch 40 is formed in the camshaft 14 at a position corresponding to the anti-theft bolt 42. A shutter, which is an L-shaped plate 45 in this embodiment, is fixed to the step 24 by a pin 46. The long portion of the plate 45 extends in the axial direction of the device 11. The plate 45 is located between the anti-theft bolt 42 and the notch 40 to close the bore 44 and prevents the anti-theft bolt 42 from projecting into the first cylindrical chamber 22.

A break-away groove 12a is formed between the lid 19 and the step 24. If an attempt is made to break the housing 12, the main casing 20 will break along the break-away groove 12a. Therefore, the bolt 16 will still be able to lock the steering shaft.

The operation of the device 11 will now be described.

Fig. 1 illustrates the device 11 when the key K is not inserted therein. In this state, the key rotor 31 is at the LOCK position and the coupler 15 is not lifted. The distal end of the bolt 16 is engaged with the recess 71 of the steering shaft 70, which locks the steering shaft 70 against rotation.

If the key K is inserted into the key cylinder 13 and the serration of the key K matches with the tumblers, the key rotor 31 is unlocked. The key rotor 31 can be rotated from the LOCK position to the ACC position, or in a direction unlocking the steering shaft 70.

When rotated from the LOCK position to the ACC position, the key K rotates the camshaft 14 in the same direction through the key rotor 31 to a position unlocking the steering shaft 70. That is, the cam 35 pushes the coupler 15 against the force of the spring 18, which moves the coupler 15 to unlock the steering shaft 70.

The distal end of the bolt 16 is disengaged from the recess 71, which permits the steering shaft 70 to be rotated.

As long as the key K is inserted in the key cylinder 13, the coupler 15 is maintained at the position of Fig. 2, which maintains the bolt 16 in the unlocked position. Rotating the key K to the ST position or to the LOCK position from the ACC position does not move the bolt 16.

If the key K is removed after being rotated from the ACC position to the LOCK position, the bolt 16 is moved by the force of the spring 18 through the coupler 15. The bolt 16 is moved from the unlocked position to the locked position.

Accordingly, the bolt 16 extends into the steering post (not shown) and engages the recess 71 of the steering shaft 70, which locks the steering shaft 70 against rotation.

If somebody tries to break away the front portion of the housing 12, the housing 12 is broken at the break-away groove 12a as illustrated in Fig 4. The second cylindrical chamber 23, which includes the step 24, is removed with the key cylinder 13. The camshaft 14 is thus exposed.

When the front portion of the housing 12 is removed, the plate 45 is also removed from the device. The anti-theft bolt 42 is moved by the spring 43 and engages with the notch 40, which prevents the camshaft 14 from rotating. The bolt 16 is engaged with the recess 71, which locks the steering shaft 70. As a result, the steering wheel cannot be manipulated. Also, the ignition switch cannot be actuated, which deters theft of the car.

The device 11 of Figs. 1 to 4 has the following advantages.

The anti-theft bolt 42 is urged toward the camshaft 14 by the spring 43. The camshaft 14 has the notch 40 at a position corresponding to the anti-theft bolt 42. The housing 12 has the break-away groove 12a. When strong force is applied to the housing 12, the housing 12 fractures along the groove 12a. When the housing 12 is removed, the plate 45 is also removed with the housing 12. Therefore, the antitheft bolt 42 engages the notch 40 only when the housing 12 is broken, which prevents the camshaft 14 from rotating.

The anti-theft mechanism includes the break-away groove 12a, the notch 40 formed in the camshaft 14, the lock pin, the spring 43, and the plate 45. In other words, the mechanism adds only few parts, which are the anti-theft bolt 42, the coil spring 43 and the plate 45, to the structure.

Thus, the device 11 is inexpensive.

When the housing 12 is broken, the plate 45 is removed with the housing 12. Therefore, the mechanism does not increase the axial size of the housing 12. In other words, the size of the device 11 is reduced compared to the prior art.

A steering wheel locking device 50 according to a second embodiment will now be described with reference to Fig 5. The differences from the embodiment of Figs-1 to 4 will mainly be discussed below.

The steering wheel locking device 50 includes a recess 51 formed in the camshaft 14. The lock pin 52 is accommodated in the recess 51. The lock pin 52 is movable in the radial direction of the camshaft 14, or in the radial direction of the housing 12. An urging member, which is a spring 53, is located between the proximal end of the lock pin 52 and the bottom of the recess 51. The spring 53 urges the lock pin 52 toward the first cylindrical chamber 22.

A notch 54 is formed in the inner wall of the first cylindrical chamber 22. A plate 55 is fixed to the outer surface of the key rotor 31 by a pin 56. The long portion of the plate 55 extends parallel to the axis of the device 50.

The plate 55 is located between the lock pin 52 and the notch 54 to close the recess 51. The plate 55 blocks the lock pin 52 from extending into the first cylindrical chamber 22.

When the key cylinder 13 is at a predetermined position, that is when the key cylinder 13 is located in the housing 12, the correct key K unlocks key rotor 31. The key K can therefore be rotated to unlock the steering shaft.

When broken, the housing 12 is broken along the groove 12a. If the key cylinder 13 is removed, the camshaft 14 is exposed, which makes the camshaft 14 susceptible to manual rotation.

When the key cylinder 13 is removed, the plate 55 is also removed from the space between the lock pin 52 and the notch 54. The lock pin 52 is thus moved toward the first cylindrical chamber 22 by the spring 53 and engages with the notch 54. The lock pin 52 prevents the camshaft 14 from rotating. The bolt 16 is engaged with the recess 71 of the steering shaft 70, which locks the steering shaft 70 against rotation. Accordingly, like the device 50 of Figs. 1 to 4, the device 50 of Fig. 5 deters theft of the car.

As in the embodiment of Figs. 1 to 4, when the key cylinder 13 is removed from the housing 12, the lock pin 52 engages the notch 54. Accordingly, the camshaft 14 is prevented from rotating.

The anti-theft mechanism of Fig. 5 includes the lock pin 52 and the spring 53 located in the camshaft 14, the notch 54 formed in the housing 12 and the plate 55. In other words, the mechanism adds only few parts, which are the lock pin 52, the spring 53 and the plate 55, to a steering device.

Thus, the device 50 is inexpensive.

When the key cylinder 13 is removed from the housing 12, the plate 55 is also removed with the key cylinder 13. The size of the device 11 is therefore reduced.

It should be apparent to those skilled in the art that the present invention may be embodied in many other specific forms without departing from the spirit or scope of the invention. Particularly, it should be understood that the invention may be embodied in the following forms.

The break-away groove 12a may be replaced by a series of recesses or perforations formed about the circumference of the housing 12.

It should be apparent to those skilled in the art that the present invention may be embodied in many other specific forms without departing from the spirit or scope of the invention. Therefore, the present examples and embodiments are to be considered as illustrative and not restrictive and the invention is not to be limited to the details given herein, but may be modified within the scope and equivalence of the appended claims.

Claims

Claims: 1. A locking device for locking a steering shaft (70) for a vehicle, the locking device being characterized by: a housing (12), wherein the housing (12) has a proximal portion (21), which is attached to the vehicle, and a distal portion (20), which extends from the proximal portion (21); a key cylinder (13) supported by the proximal portion (21) of the housing (12), wherein the key cylinder (13) has a key rotor (31), which is rotated by a key; a cam shaft (14) rotatably supported by the distal portion (20) of the housing (12), wherein the cam shaft (14) is integrally connected to the key rotor (31), the cam shaft (14) having a cam; a locking member (15,16) moved by the cam, wherein the cam causes the locking member (15,16) to lock the steering shaft (70) when the key rotor (31) is rotated to a predetermined lock position; an opening (40,54) formed in one of the cam shaft (14) and the proximal portion (21) ; an engagement member (42,52) that is movable in the radial direction of the cam shaft (14) to enter the opening (40,54), the engagement member (42,52) being supported by the other of the cam shaft (14) and the proximal portion (21), wherein the rotation of the cam shaft (14) with respect to the proximal portion (21) is prevented and the locking member (15,16) locks the cam shaft (14) against the rotation when the engagement member (42,52) has entered the opening (40, 54); an urging member (43,53) for urging the engagement member (42,52) toward the opening (40, 54); and a shutter (45,55) attached to the distal portion (20) of the housing (12) or the key cylinder (13), wherein the shutter (45,55) extends between the opening (40,54) and the engagement member (42,52) to block the engagement member (42, 52) from entering the opening (40, 54).
2. The locking device according to claim 1, characterized in that the housing (12) has a weakened portion (12a), which is easily broken compared to the remainder of the housing (12), wherein the weakened portion (12a) is located between the proximal portion (21) and the distal portion (20).
3. The locking device according to claim 2, characterized in that the weakened portion (12a) includes a groove.
4. The locking device according to any one of claims 1 to 3, characterized in that the opening (40,54) is formed in the cam shaft (14), wherein the engagement member (42,52) is supported by the proximal portion (21) and the shutter (45, 55) is attached to the distal portion (20) of the housing (12).
5. The locking device according to claim 4, characterized in that the proximal portion (21) has a hole (41) for accommodating the engagement member (42, 52), wherein the shutter (45, 55) closes the hole (41) such that the engagement member (42,52) substantially does not extend from the hole (41, 51).
6. The locking device according to any one of claims 1 to 3, characterized in that the opening (40,54) is formed in the proximal portion (21) of the housing (12), wherein the engagement member (42,52) is supported by the cam shaft (14), and the shutter (45, 55) is attached to the key rotor (31).
7. The locking device according to claim 6, characterized in that the cam shaft (14) has a hole (51) for accommodating the engagement member (42,52), wherein the shutter (45,55) blocks the hole (51) such that the engagement member (42,52) substantially does not extend from the hole (41, 51).