Patent Publication Number: US-2007113604-A1

Title: Steering lock device

Description:
BACKGROUND OF THE INVENTION  
      1. Field of the Invention  
      The present invention relates to locking devices used in automotive applications. The invention more particularly concerns the locking of a steering shaft to a steering column of an automobile so as to prevent rotation of the steering shaft during selected periods of time. Thus, the locking device can be used as a safety device and an anti-theft device.  
      2. Description of the Prior Art  
      For years now, automobile manufacturers have been including, as a standard feature, the feature of an immobilized steering shaft when the ignition key is not inserted into the ignition switch. The immobilized steering shaft prevents the steering wheel from rotating, thus, someone not having the ignition key can not steer the car if the car is hot-wired or if someone attempts to push the car away. The theft deterrent function works so well that people who attempt to take a car without using a key, typically, employ a large screwdriver-type of device inserted into the opening for the ignition key to break, cut open, and remove the ignition device that immobilizes the steering shaft. Thus, in a single act of violence, the person breaking into the vehicle can disable both the ignition function and the steering immobilization function. Once the person has successfully removed the device, the vehicle can then be easily hot-wired and driven away. A device that integrates the two functions is disclosed in U.S. Pat. No. 5,848,540.  
      Attempts have been made to separate the ignition function and the anti-rotation of the steering wheel function to complicate the act of automobile theft. The person attempting to steal an automobile would need to disengage the anti-rotation device and the ignition switch separately, which consumes much more time and makes it more likely that the person will be caught in the act. As such, it is presumed that a person inclined to steal the automobile of another person will not do so since the risk is not worth the effort. An example of a device that focuses on one of the functions, the anti-rotation function, is disclosed in U.S. Pat. No. 5,896,765, and European Patent Application No. EP 764566A1. However, highly motivated car thieves may take their chances and attempt to steal an automobile incorporating the steering wheel locking devices disclosed in U.S. Pat. No. 5,896,765. The car thief would find that the locking element is one large piece of material. The car thief can beat or impact on it with push loads and either bend it, locally bend the steering shaft, or break the housing around the locking element, thus disarming the locking function.  
      An added benefit of placing the ignition switch in another location such as the dashboard is that the steering column area is made less busy for the driver of the vehicle. This is important because, currently, the steering column area is very busy, since it incorporates controls for directional indicators, head lamps, cruise control, windshield wipers, and etc.  
      Thus, there is a need for a steering lock device which is separate from the ignition switch and which prevents the destruction of the locking element when a thief attempts to disengage the steering lock device.  
     SUMMARY AND OBJECTS OF THE INVENTION  
      An object of the invention is to provide a device which decreases the probability that a thief will be able to steer the wheel of a hot-wired automobile. Another object of the invention is to provide a steering lock device that separates the ignition function from the anti-rotation function.  
      Disclosed are four independent design features that decrease the probability that a thief will be able to steer the wheel of a hot-wired automobile. The first feature of the invention includes a steering lock device that separates the ignition function from the anti-rotation function.  
      The second feature is a safety system which includes a clutch mechanism and a lock bolt drive system that provides a lock bolt that can be engaged/disengaged with the steering shaft when the ignition key is turned to start or stop the automobile.  
      The third feature is the use of a protective shield as part of the lock device case. This feature makes any thief intervention from the outside very difficult.  
      The fourth feature is a safety system that locks the locking bolt if the metal case is broken or if any key mechanical component inside becomes loose.  
      In the present invention, the lock bolt is engageable with a recess formed on the surface of the steering shaft. In a locked position, the lock bolt engages the recess of the steering shaft. In an unlocked position, the lock bolt is withdrawn and disengaged from the recess. When the ignition key is turned to start the automobile, the lock bolt disengages the steering shaft. When the ignition key is turned to stop the automobile engine from idling, the lock bolt engages the steering shaft.  
      Thus, the invention achieves the objectives set forth above. The invention provides a device which is physically separate from the ignition function and which increases the effort required to steal an automobile equipped with the steering lock device. Additionally, the device fits within existing real estate on the steering column and has few moving parts which are inexpensive to produce and assemble. Therefore, even in the most violent of environments, the steering lock device will perform as intended and deter the theft of the vehicle. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
      The preferred embodiments of this invention will be described in detail, with reference to the following figures, wherein:  
       FIG. 1  illustrates a first embodiment of the steering lock device of the present invention;  
       FIG. 2  illustrates the steering lock device of  FIG. 1  mounted on a shaft;  
       FIG. 3  illustrates a clutch device wheel and a contact according to the first embodiment of the present invention;  
       FIG. 4  illustrates a retainer assembly according to the first embodiment of the present invention;  
       FIG. 5  illustrates a bottom view of the retainer assembly of  FIG. 5 ;  
       FIG. 6  illustrates the steering lock device in a lock position;  
       FIG. 7  illustrates the steering lock device in an unlock position;  
       FIG. 8  illustrates a second embodiment of the steering lock device of the present invention;  
       FIG. 9  illustrates the steering lock device of  FIG. 8  mounted on a shaft; and  
       FIG. 10  illustrates a third embodiment of the steering lock device of the present invention.  
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
      The present invention includes a locking device for locking a steering shaft to a steering column to prevent rotation of the steering shaft during a period of time. The locking device may be used as a safety and anti-theft device for automobiles.  
      The present invention provides a steering lock device that separates the ignition function from the anti-rotation function. A clutch mechanism and a lock bolt drive system provide a lock bolt that can be engaged/disengaged with the steering shaft when the ignition key is turned to start or stop the automobile. A metal case covering the lock mechanism makes any thief intervention from outside very difficult.  
      The system of the present invention locks the locking bolt if the metal case is broken or any key mechanical component inside becomes loose.  
      Referring now to the drawings, wherein like reference numerals designate identical or corresponding parts throughout the several views, and more particularly to  FIGS. 1-2  thereof, an embodiment of the present invention is a steering lock device with safety system  100  as shown in  FIG. 1  as an exploded perspective view.  
      The steering lock device includes a lock bolt  134 ; a clutch mechanism (and clutch housing  138 ) with spring loaded rollers (combination of  118  and  120 ); a worm wheel  146 ; a contact/sensing system for lock bolt position detection (not shown); a PCB assembly  106  with a connector; an electric motor  140  with the worm  112  connected to the motor shaft; a motor shock absorption system (not shown); security pins  124  and springs; a PCB, motor, and lock bolt clutch mechanism retainer  148 ; and a cover  102  and housing  130 .  
      In the system of  FIG. 1 , a unique clutch mechanism is incorporated with the lock bolt  134 . The clutch mechanism includes a set of spring loaded rollers ( 118  and  120 ) located between the clutch detent profiles. These provide free bolt movement to lock and unlock positions. Any misalignment between the bolt and the recess (not shown) formed on the surface of the steering shaft (when the bolt moves to a lock position) and the bolt stall condition (when the bolt is withdrawn from the recess) is compensated by the rollers  118  movement along the clutch detent profiles.  
      The bolt drive mechanism includes a clutch housing  138 , worm wheel  146  and driving pin  110 . The clutch housing  138  has a closed spiral groove tilted at 10 degrees which may provide 4.5 mm bolt travel reciprocally, with one directional motor. The motor worm meshed with the drive wheel provides a 50:1 ratio.  
      A description of the operation of the system of  FIG. 1  follows.  FIG. 1  illustrates a motor  140  having a worm  112 . The worm  112  is the rotational output of the motor  140 . The worm  112  meshes with a worm wheel  146 . The worm wheel  146  is rotatably mounted in a retainer  148 . A large O-ring  144  and a small O-ring  142  attach to the motor  140 . A printed circuit board (PCB)  106  is situated between the retainer  148  and a cover  102 . The PCB  106  contains the logic which controls the motor  140 . Attached to the lock bolt  134  is the lock bolt return spring  122 . Screws  104  align the cover  102  with the housing  130 . The sliding contact  108  is electrically connected to the PCB  106 .  
      In operation in one state, the lock bolt  134  engages a recess on the surface of the steering shaft (not shown). The lock bolt return springs  122  is in a compressed state. A lock bolt contact (not shown) is attached to the housing  130  and sends an electrical signal to the PCB  106  when the lock bolt  134  is in the engaged position. The lock bolt contact sends and electrical signal to the PCB  106  when the lock bolt  134  is in the engaged or locked position since the lock bolt  134  touches the lock bolt contact. Likewise, when the lock bolt  134  is withdrawn from the recess, the lock bolt contact alters the signal sent to the PCB  106 , thus indicating that the lock bolt  134  is not fully engaged with the recess of the steering shaft.  
      When the ignition key is introduced into the ignition and is rotated, the ignition switch sends an electrical signal to the PCB  106 . The PCB  106  sends a signal to the motor  140 , the motor  140  rotates the worm  112 , and the worm  112  rotates the worm wheel  146 . The lock bolt  134  is fully removable from the recess in the surface of the steering shaft thus allowing the steering shaft to rotate.  
      When the ignition key is rotated so as to be removed from the ignition switch, the ignition switch sends a signal to the PCB  106 . The PCB  106  sends a signal to the motor  140 . The motor  140  rotates the worm  112 . The worm  112  rotates the worm wheel  146 . The lock bolt  134  engages the recess on the surface of the steering shaft thus locking up the steering shaft. At this position, the motor  140  stops turning.  
      Other elements included in  FIG. 1  as part of the lock bolt mechanism are the sleeve  114 , magnet  116 , rolled pin  128 , fork  132 , and actuator  136 .  
       FIG. 2  illustrates the steering lock device of  FIG. 1  assembled in a retainer and mounted on a shaft  213 . The device  100  is shown in an unlock position.  FIG. 2  shows a security pin  211  which moves inside the lock bolt if the device housing is damaged. The figure also shows a recess area  215  on the shaft&#39;s collar.  
       FIG. 3  illustrates a clutch mechanism  300  that may be used in the embodiment of  FIG. 1 . The clutch mechanism  300 , incorporated with the lock bolt  301 , has a set of spring loaded rollers  303  located between the clutch detent profiles  305 ,  307 . The clutch mechanism  300  provides free bolt movement to lock and unlock positions. Any misalignment between the bolt  301  and the recess  215  formed on the surface of the steering shaft makes the bolt stall. The motor continued rotation will be compensated by the rollers movement along the clutch detent profiles.  
      If the lock bolt  301  is not aligned with the shaft recess  215  (moving to lock position) the lock bolt  301  is pushed up against the steering shaft. The motor would continue to attempt rotation and moves the clutch housing  309  toward the steering shaft recess  215  while the clutch rollers  303  slide along the top detent profiles  305 , compressing the clutch spring. Once the steering shaft is slightly rotated so that the recess  215  aligns the lock bolt  301 , the steering shaft will pop into the recess  215  due to the force supplied by the overly compressed clutch spring.  
      When the lock bolt  301  is stalled into the recess during the unlock position, the motor moves the clutch housing  309  up and pushes the rollers towards each other along the lower clutch housing detent profiles  307 . The spring compression force is enough to overcome the friction between the lock bolt  301  and the recess  215 .  
      The bolt drive mechanism of the present invention may include a clutch assembly, drive wheel with driving pin, motor and gear train. In addition to the clutch assembly  300 ,  FIG. 3  illustrates a drive wheel mechanism  320 .  
      The clutch housing  309  has a closed spiral groove tilted at 10 degrees from the horizontal plane. The drive wheel  321  is located over this area such that a metal pin is inserted into the grove. When the drive wheel  321  rotates (the part may have one degree of freedom), the pin slides along the groove and pushes the clutch assembly  300  to move up or down depending on the groove current position. The 10 degree groove plane may reciprocally provide 4.5 mm of bolt travel.  
      The motor operates at high speed and provides low torque. The gear ratio through the worm and worm gear is very large and outputs low speed and high torque. The large torque is converted into a force at the interface between the drive pin and clutch groove. The force is large enough to overcome the force produced by the rollers compressing the clutch spring due to any misalignment. The motor worm meshed with the drive wheel  321  may provide a 50:1 ratio.  
       FIG. 3  also illustrates a sensing system for bolt position detection. A contact  323  is attached to the drive wheel  321  to detect the lock bolt  301  position. The contact  323  sends an electrical signal to a PCB (not shown) when the lock bolt  301  is in either the lock or unlock position. When the ignition key is in and is rotated, the ignition switch (not shown) sends an electrical signal to the PCB. The PCB sends a signal to motor, which rotates the worm  401  (see  FIG. 4 ). The worm  401  rotates the worm gear, which activates the clutch mechanism  300  with the bolt  301 . The device stays in this position while the engine of the vehicle is operating, i.e., the ignition key is in the ignition and has been rotated so as to start the vehicle. The logic in the PCB signals the battery to stop sending power to the motor. When the ignition key is rotated so as to be removed from the ignition switch, the ignition switch sends a signal to the PCB which causes the bolt  301  to become engaged with the steering shaft recess  215 . The locking bolt state is detected also by a magnet  327  on the actuator  325  located on the clutch assembly  300 .  
       FIG. 4  illustrates the clutch assembly  300  in a retainer  400 .  FIG. 5  illustrates a bottom view of the retainer assembly  400 .  FIG. 5  illustrates the clutch assembly  300 ; drive wheel  321 ; lock bolt  301 ; worm wheel  501 ; worm  401 ; motor  503 ; and O-rings  505 .  
       FIG. 6  illustrates the steering lock device of the present invention in a lock position.  FIG. 6  illustrates a device cover  705 ; a PCB  703 ; drive wheel  321 ; a device housing  701 ; clutch housing  309 ; worm wheel  501 ; a rollers-spring assembly  709 ; detent profiles  305 ,  307 ; the retainer  400 ; and the drive pin  707 . Most importantly,  FIG. 6  illustrates the bolt  301  in the lock position (engaging the recess area  215  of the shaft), thus blocking the shaft.  
       FIG. 7  illustrates the steering lock device in the unlock position according to one embodiment of the present invention. The figure shows that the bolt  301  does not engage the shaft recess  215 . The shaft is then free to rotate.  
       FIG. 8  illustrates a second embodiment  800  of the steering lock device of the present invention. The steering lock device may include a housing  801 ; contact carrier  803 ; contact carrier driver  805 ; a retainer with right ( 807 ) and left ( 833 ) sides; motor  809 ; clutch housing  811 ; lock bolt  813 ; clutch roller  815 ; screws  817 ; locking pin  819 ; spring  821 ; base  823 ; fork  825 ; worm shaft  827 ; worm  829 ; bushing  831 ; contact  835 ; PCB  837 ; drive wheel  839 ; and eccentric  841 .  
      The main difference between the steering lock device  800  and the device  100  is the bolt drive mechanism. The bolt drive mechanism of the device  800  may be based on an eccentrically located round shape cam  841  that engages with clutch pins. The cam may be positioned at 90 degrees from the bolt movement direction, which may require different packaging and different parts design from the device  100 . The eccentrically located cam  841  may have a 4.5 mm offset to provide the corresponding lock bolt movement. Other major components in the device  800  function similar to those in the device  100 , but may have a different shape.  FIG. 9  illustrates the steering lock device  800  mounted on a shaft  901 .  
       FIG. 10  illustrates a third embodiment of the steering lock device of the present invention. The third embodiment may include a lock housing  1 ; a base  2 ; lock bolt  3 ; lock bolt carrier  4 ; contact spring bolt  5 ; roller  6 ; spring  7 ; clutch  8 ; rotor  9 ; contact spring clutch  10 ; belt  11 ; yoke  12 ; roller  13 ; motor  14 ; cable  15 ; and housing  16 .  
      The third embodiment mainly differs from the first and second embodiments in that it uses a different gear train to activate the clutch mechanism. The hypocycloid gear reduction mechanism includes the motor  14 , belt  11 , yoke  12  and roller  13 . The motor shaft may be attached to the center roller  13  which is in mesh with the yoke  12  (two planetary gears). The yoke  12  activates an outside gear which is attached to a drive wheel. This gear train produces a large reduction ratio, offers low sliding, high stress loading and long life.  
      The disclosed designs have very low noise and relatively low friction because the drive systems exert a low force and the motor is isolated from the metal housing.  
      While this invention has been described in conjunction with the specific embodiments outlined above, it is evident that many alternatives, modifications and variations are apparent to those skilled in the art. Accordingly, the preferred embodiments of the invention as set forth above are intended to be illustrative and not limiting. Various changes may be made without departing from the spirit and scope of the invention.