Electric steering lock device

There are provided a cam plate (5) that rotates in an unlocking direction and a locking direction, and a locking shaft (8) that moves between a locking position where rotation of a steering shaft is prevented and an unlocking position where the rotation of the steering shaft is permitted by rotation of the cam plate (5). The cam plate (5) is provided with a steering lock preventing unit (20) through a spring (22). The steering lock preventing unit (20) holds the locking shaft (8) in the unlocking position. A ball (23) moves on a moving surface (24) of a motor unit (4) opposed to the cam plate (5) by rotation of the cam plate (5). A projecting wall (25) is provided on the moving surface (24) at a position before the unlocking position in a range where the ball (23) moves from the locking position to the unlocking position.

TECHNICAL FIELD

The present invention relates to an electric steering locking apparatus that locks a steering shaft of an automobile.

BACKGROUND ART

Japanese Patent Application Laid-Open No. 2000-154674 discloses a conventional electric steering locking apparatus of this kind. This electric steering locking apparatus mainly includes a cam member that rotates in an unlocking direction and a locking direction by driving operation of a drive source, a locking member that follows a sliding surface of the cam member and moves between a locking position where the rotation of a steering shaft is locked and an unlocking position where the rotation of the steering shaft is permitted, a spring that biases the locking member toward the locking position, and a steering lock preventing unit that holds the locking member in the unlocking position.

The steering lock preventing unit includes a holding lever connected to an operation knob through a connection member. When the holding lever enters an engaging groove of the locking member located in the unlocking position, the locking member is locked.

With the above configuration, while a vehicle is parked, the locking member is located in the locking position and the steering shaft is locked. Thus, the vehicle can be theftproof during parking.

When a parked vehicle is to be driven, the cam member rotates in the unlocking direction by the driving operation of the drive source, the locking member is brought into the unlocking position, and the rotation of the steering shaft is permitted. When the locking member is located in the unlocking position, the holding lever of the steering lock preventing unit enters into the engaging groove of the locking member, and the locking member is locked so as not to move to the locking position. With this configuration, even when an external force toward the locking position is applied to the cam member or the locking member due to abrupt vibration or the like during running, it is possible to prevent the locking member biased by the spring from moving toward the locking position to lock the steering shaft.

DISCLOSURE OF THE INVENTION

The steering lock preventing unit of the conventional electric steering locking apparatus is mechanically associated with the operation knob. Therefore, there is a problem that the configuration is complicated, installation space is large, and cost is high. There is also a problem that a striking sound caused when the holding lever enters the engaging groove of the locking member is loud.

Another conventional steering lock preventing unit includes an electromagnetic solenoid which is turned ON and OFF in association with an operation position of the operation knob, and an engaging plate which is moved by the electromagnetic solenoid and which is engaged with and disengaged from the engaging groove of the locking member. However, even with the electromagnetic solenoid, the same problem as the former conventional technique arises.

It is an object of the invention to provide an electric steering locking apparatus in which a configuration thereof is simple, installation space is small, cost is low, and a striking sound caused when the locking member in an unlocking position is locked is small.

To achieve the above object, according to an aspect of the present invention, there is provided an electric steering locking apparatus including a cam member that rotates in an unlocking direction and a locking direction by driving operation of a drive source, a locking member that moves between a locking position where a steering shaft is prevented from rotating and an unlocking position where the steering shaft is permitted to rotate by rotation of the cam member, and a steering lock preventing unit that holds the locking member in the unlocking position, wherein the steering lock preventing unit includes a moving member which is provided on one of the cam member and a member opposed to the cam member and which is moved by rotation of the cam member, and a resisting unit which is provided on the other member, and which increases a moving resistance when the moving member moves from the unlocking position to the locking position on a moving locus of the moving member.

With this configuration, since it is only necessary that the cam member and the member opposed thereto are provided with the moving member, the resisting unit, and the like the configuration can be simplified, the installation space is reduced, and the cost can be reduced. The moving member moves on the opposed member by rotation of the cam member and the locking member is locked in the unlocking position by the moving resistance. Thus, almost no striking sound is generated when the locking member is locked in the unlocking position.

The moving member may be a ball biased toward the opposed member by a biasing unit. With this configuration, since the ball moves on the opposed member, wear of the moving surface can be prevented as much as possible.

The resisting unit may be a projecting wall provided at a position immediately before the unlocking position on a sliding locus. The resisting unit may be a groove formed in the unlocking position on the sliding locus.

BEST MODE FOR CARRYING OUT THE INVENTION

As shown inFIGS. 1,2, and7, an electric steering locking apparatus1includes a frame2and a cover3that covers an upper portion of the frame2. A motor unit4which is a drive source is fixed on the frame2covered with the cover3. The motor unit4includes a speed reduction mechanism therein, and a cam plate5which is a cam member is fixed to a rotation shaft4a(shown inFIGS. 4 and 5) projecting from a unit case.

The cam plate5is rotated in an unlocking direction R1and its opposite locking direction R2by rotation of the rotation shaft4a. An outer peripheral surface of the cam plate5is formed as a sliding surface6. The sliding surface6is set such that a distance from a rotation center O to the sliding surface6is gradually varied as a rotation angle is varied. A distance to a contact position where the locking shaft8is brought to the locking position is set to be the shortest distance, and a distance to a contact position where the locking shaft8is brought to the unlocking position is set to be the longest distance.

The frame2is formed with a sliding hole7penetrating the frame2in a vertical direction. The locking shaft8which is a locking member is movably disposed in the sliding hole7. A hanger portion9is fixed to an upper end of the locking shaft8. A lower surface of the hanger portion9is formed as a cam abutment surface10. The cam abutment surface10abuts against the sliding surface6of the cam plate5. Spring force of a spring13is applied to an upper surface of the hanger portion9. The locking shaft8is biased toward the locking position by the spring force and the cam abutment surface10is pushed by the cam plate5.

The locking shaft8is provided at its lower end with an engaging pin portion11. The locking shaft8moves by following the sliding surface6of the cam plate5, and moves between a locking position shown inFIGS. 7 and 8and an unlocking position shown inFIGS. 2 to 4. In the locking position, the engaging pin portion11enters between projections12aof a steering shaft12(state shown inFIG. 8), thereby preventing rotation of the steering shaft12. In the unlocking position, the engaging pin portion11is located out of rotation locus of the projections12aof the steering shaft12(state shown inFIG. 3), thereby permitting the rotation of the steering shaft12.

As shown inFIGS. 3 to 6and8, the electric steering locking apparatus1includes a steering lock preventing unit20. The steering lock preventing unit20includes a spring22which is a biasing unit disposed in a recess21formed in a side surface of the cam plate5, a ball23which is a moving member supported on a tip end of the spring22, and a projecting wall25which is a resisting unit projecting on a stationary surface24of the ball23. The stationary surface24is a side surface of the motor unit4which is a member opposed to a side surface of the cam plate5. The projecting wall25is disposed immediately before the unlocking position in a range where the ball23moves from the locking position to the unlocking position.

When the cam plate5rotates, the ball23moves on the stationary surface24. At the position of the projecting wall25, the ball23retreats into the recess21against the spring force of the spring22and crosses over the projecting wall25. In the unlocking position of the locking shaft8, as shown inFIGS. 5 and 6, the ball23is located at a position where the ball23crosses over the projecting wall25, and the locking shaft8is held at the unlocking position by the moving resistant force. To move the cam plate5toward the locking position from the unlocking position, the cam plate5can rotate only when a large driving force of the motor unit4is applied.

With the above configuration, while the vehicle is parked, the locking shaft8is located in the locking position shown inFIGS. 7 and 8, and the rotation of the steering shaft12is locked. Thus, the vehicle can be theftproof.

If a driver carries out a predetermined operation to start an engine, the motor unit4is driven and the cam plate5is rotated to the unlocking direction R1. With this, the locking shaft8moves to the unlocking position shown inFIGS. 2 to 5, and the steering shaft12is permitted to rotate. The ball23moves on the moving surface24of the motor unit4together with rotation of the cam plate5, and in the unlocking position of the locking shaft8, the ball23moves to and stops at a position where the ball23crosses over the projecting wall25. Even when an external force toward the locking position is applied to the cam plate5or the locking shaft8due to abrupt vibration or the like during running, the cam plate5is prevented from moving toward the locking position by a great moving resistance caused by the ball23and the projecting wall25. The locking force of the steering lock preventing unit20prevents the locking shaft8from locking the steering shaft12.

Next, if the driver carries out a predetermined operation to park the vehicle, the motor unit4is driven to rotate the cam plate5to the locking direction R2. Then, the ball23crosses over the projecting wall25by the rotation force of the cam plate5and the cam plate5is permitted to rotate in the locking direction R2. When the ball23crosses over the projecting wall25, the locked state by the steering lock preventing unit20is released. By the rotation of the cam plate5, the locking shaft8moves in the locking position shown inFIGS. 7 and 8, and the steering shaft12is prevented from rotating.

According to the steering lock preventing unit20of the electric steering locking apparatus1, since it is only necessary that the cam plate5and the motor unit4opposed thereto are provided with the ball23, the projecting wall25, and the like, the configuration can be simplified, the installation space is reduced, and the cost can be reduced. Since the locking shaft8is locked in the unlocking position when the ball23moves on the moving surface24, almost no striking sound is generated when the locking shaft8is locked in the unlocking position.

FIGS. 9 and 10show a modification of the steering lock preventing unit of the embodiment.FIG. 9is a cross section when the locking shaft8is located in the unlocking position.FIG. 10is a schematic enlarged view showing a layout of the locking shaft8and the cam plate5in the unlocking position.

According to a steering lock preventing unit20A of this modification, positions of the ball23and the projecting wall25are set reversely as compared with the embodiment. That is, the steering lock preventing unit20A includes the spring22disposed in the recess21formed in a side surface of the motor unit4, the ball23which is a moving member supported by a tip end of the spring22, and the projecting wall25which is a resisting unit projecting on the moving surface24. The moving surface24is a side surface of the cam plate5opposed to a side surface of the motor unit4.

InFIGS. 9 and 10, like reference numerals denote like parts as those according to the embodiment, and redundant explanation is omitted.

From this modification also, the same effect as that of the embodiment can be obtained.

FIG. 11is a cross section of relevant parts taken along a moving surface, showing a modification of the resisting unit of the embodiment. In this modification, the resisting unit includes a groove30formed in the moving surface24of the motor unit4or the cam plate5. The groove30is formed in the unlocking position. In the unlocking position of the cam plate5, the ball23enters into the groove30so that the moving resistance when the ball23moves toward the locking position is increased.

Even when the resisting unit is the groove30as in this modification, the same effect as that of the embodiment can be obtained.

In the above embodiment and its modifications, the moving member is the ball23which is biased by the spring22which is a biasing unit. Therefore, the ball23smoothly moves on the moving surface24and thus, the wear of the moving surface24can be prevented as much as possible. The moving member may move on the moving surface24by sliding motion or rolling motion by a driving force of the motor unit4. One of the cam member and a member which is opposed to the cam member may be integrally formed with a leaf spring having a projection, the projection may not slide on a place other than the resisting unit of the steering lock preventing unit20A, and the projection may abut in the position of the resisting unit.