Steering-bracket supporting apparatus and steering apparatus

This application is a National Stage of International Application No. PCT/JP2014/080388 filed Nov. 17, 2014, claiming priority based on Japanese Patent Application Nos. 2013-240259, filed Nov. 20, 2013, and 2013-240260, filed Nov. 20, 2013, the contents of all of which are incorporated herein by reference in their entirety.

1. Field of the Invention

The present invention relates to a steering-bracket supporting apparatus, i.e. a supporting apparatus for fixing a steering bracket to a vehicle body and also relates to a steering apparatus.

2. Description of the Related Art

Prior Art 1 and 2 disclose techniques of a separation capsule in which when an excessive load is applied to a steering column attached to a vehicle and the steering column is pushed to the front of the vehicle, a part of the supporting structure is separated and the steering column thus moves to the front of the vehicle, thereby protecting a driver (operator) from a thrust (secondary collision) of a steering wheel.

Prior Art 1: JP 63-019467 U1

Prior Art 2: JP 07-081586 A

In the techniques disclosed in the Prior Art 1 and 2, since a set value of the separation load at which the steering column moves to the front of the vehicle is lowered by cutting a part of the supporting structure, there is a possibility of occurrence in malfunction, in a case of trying to protect an operator who is light in weight.

The present invention has been made in view of the above problem. An object of the present invention is to provide a steering-bracket supporting apparatus and a steering apparatus which are capable of suppressing the malfunction in an ordinary use even when a part of the supporting structure is separated and thus the set value of the separation load at which the steering column moves to the front of the vehicle.

It is an object of the present invention to at least partially solve the problems in the conventional technology. According to an aspect of the invention, a supporting apparatus for a steering bracket includes, a steering bracket supporting a steering column, the steering bracket including a first capsule-side hole and a second capsule-side hole opened thereon; a separation capsule to fix a vehicle body-side member to the steering bracket, the separation capsule including a first bracket-side hole and a second bracket-side hole opened thereon; a resin member arranged at a position straddling the first bracket-side hole and the first capsule-side hole; a shear pin arranged at a position straddling the second bracket-side hole and the second capsule-side hole; and an inertial action body including a weight portion, the weight portion arranged to move to a front side of a vehicle by inertia due to a primary collision and the inertial action body arranged to pull out the shear pin from the second bracket-side hole with a movement of the weight portion. The inertial action body includes a base portion and a claw portion obtained by dividing the base portion with a slit, and the shear pin penetrates into the slit so that a head portion of the shear pin comes into contact with a surface of the claw portion.

When a load is applied to the steering column, which is attached to the vehicle, by the impact in the ordinary use, the steering column is pushed to the front side of the vehicle and the resin member is subjected to the shearing force, and the shearing force is similarly applied to the shear pin. Thus, the fracture of the resin member is suppressed and the malfunction is suppressed during the ordinary use. Meanwhile, in the case of the collision (primary collision) of the vehicle, the inertial action body pulls out the shear pin so that a part of the supporting structure is cut and the set value of the separation load at which the steering column moves to the front side of the vehicle is lowered, thereby the supporting apparatus for the steering bracket can alleviate the impact of an operator who is light in weight.

The inertial action body includes a base portion and a claw portion obtained by dividing the base portion with a slit, and the shear pin penetrates into the slit and a head portion of the shear pin comes into contact with a surface of the claw portion. The inertial action body is clamped between the head portion of the shear pin and the surface of the separation capsule or the steering bracket, and the sliding contact surface of the inertial action body is firmly adhered to the surface of the separation capsule or the steering bracket. Therefore, frictional force is generated between the sliding contact surface of the inertial action body and the surface of the separation capsule or the steering bracket, so that the movement of the inertial action body is set to be suppressed for a relatively weak impact.

As a desirable aspect of the invention, the claw portion is formed such that the distance from a surface of the separation capsule to the surface of the claw portion with which the head of the shear pin comes into contact increases toward the base portion. Thus, the inertial action body can convert a movement into a motion in which the shear pin is pulled out from the second bracket-side hole depending on the movement amount due to the action of inertia.

As a desirable aspect of the invention, the weight portion causes the center of gravity of the inertial action body to be biased to the base portion. Thus, it is possible to set a set value of an operation load in which the inertial action body moves.

As a desirable aspect of the invention, the shear pin includes a hook portion provided at the other end of the head portion and positioned at an edge of the second bracket-side hole or the second capsule-side hole. Since the hook portion is fractured or the hook portion is deformed, the shear pin can be pulled into the second bracket-side hole or the second capsule-side hole, and hence the shear pin is pulled out from the second bracket-side hole with the movement of the inertial action body.

As a desirable aspect of the invention, one of the second bracket-side hole and the second capsule-side hole located near the head portion of the shear pin has a larger diameter than the other. Thus, it is possible to improve the possibility of pulling out the shear pin even when the posture of the shear pin is inclined.

As a desirable aspect of the invention, a guide surface is provided on the surface of the separation capsule or the steering bracket so as to guide a movement direction of an inertial action body 15 due to action of inertia. Even when a moment load including a rotational component is applied to the inertial action body, the shear pin can be pulled out along the guide surface by the inertial action body.

As a desirable aspect of the invention, a steering apparatus is supported by the supporting apparatus for the steering bracket Thus, the steering apparatus can further protect an operator who is light in weight by cutting a part of the supporting structure to lower the set value of the separation load at which the steering column moves to the front side of the vehicle.

According to the present invention, it is possible to provide a steering-bracket supporting apparatus and a steering apparatus which can suppress the malfunction in an ordinary use even when a part of the supporting structure is cut and thus the set value of the separation load at which a steering column moves to the front of the vehicle is lowered.

FIG. 1 is a constitution diagram of an electric power steering apparatus provided with an electric motor according to a first embodiment.

FIG. 2 is a side view schematically illustrating a periphery of a steering column.

FIG. 3 is a plan view schematically illustrating a supporting apparatus for a steering bracket that is used to attach a steering column to a vehicle.

FIG. 4 is a perspective view schematically illustrating a portion in which the steering column is attached to the vehicle.

FIG. 5 is a schematic cross-sectional view illustrating a state before the supporting apparatus for the steering bracket according to the first embodiment is separated.

FIG. 6 is a perspective view schematically illustrating an inertial action body according to the first embodiment.

FIG. 7 is a schematic cross-sectional view illustrating a state where the shear pin is pulled out in the supporting apparatus for the steering bracket according to the first embodiment.

FIG. 8 is a schematic cross-sectional view illustrating a state after the supporting apparatus for the steering bracket according to the first embodiment is separated.

FIG. 9 is a schematic cross-sectional view illustrating a state before a supporting apparatus for a steering bracket according to a second embodiment is separated.

FIG. 10 is a schematic cross-sectional view illustrating a state where a shear pin of the supporting apparatus for the steering bracket according to the second embodiment is pulled out.

FIG. 11 is a schematic cross-sectional view illustrating a state before a supporting apparatus for a steering bracket according to a third embodiment is separated.

FIG. 12 is a schematic cross-sectional view illustrating a state before a supporting apparatus for a steering bracket according to a fourth embodiment is separated.

FIG. 13 is a plan view schematically illustrating a supporting apparatus for a steering bracket to attach a steering column to a vehicle.

FIG. 14 is a perspective view schematically illustrating a portion where the steering column is attached to the vehicle.

FIG. 15 is a perspective view schematically illustrating a portion where a steering column according to a fifth embodiment is attached to the vehicle.

FIG. 16 is a schematic cross-sectional view illustrating a state before a supporting apparatus for a steering bracket according to the fifth embodiment is separated.

FIG. 17 is a perspective view schematically illustrating protrusion portions of a cam rotor of a cam mechanism according to the fifth embodiment.

FIG. 18 is a schematic cross-sectional view illustrating a state a shear pin of the supporting apparatus for the steering bracket according to the fifth embodiment is pulled out.

FIG. 19 is a schematic cross-sectional view illustrating a state after the supporting apparatus for the steering bracket according to the fifth embodiment is separated.

FIG. 20 is a schematic cross-sectional view illustrating a state before a supporting apparatus for a steering bracket according to a sixth embodiment is separated.

FIG. 21 is a schematic cross-sectional view illustrating a state before a supporting apparatus for a steering bracket according to a seventh embodiment is separated.

FIG. 22 is a schematic diagram of a washer of the supporting apparatus for the steering bracket according to the seventh embodiment.

Embodiments of the present invention will be described in detail with reference to the drawings. The present invention is not limited by the contents described in the following embodiments. In addition, elements described below include those that are easily conceived by a person skilled in the art and that are substantially the same. Further, the elements described below can be properly combined.

First Embodiment

FIG. 1 is a constitution diagram an electric power steering apparatus provided with an electric motor according to a first embodiment. FIG. 2 is a side view schematically illustrating a periphery of a steering column. FIG. 3 is a plan view schematically illustrating a supporting apparatus for a steering bracket that is used to attach a steering column to a vehicle. FIG. 4 is a perspective view schematically illustrating a portion in which the steering column is attached to the vehicle. FIG. 5 is a schematic cross-sectional view illustrating a state before the supporting apparatus for the steering bracket according to the first embodiment is separated. FIG. 5 is a cross-sectional view taken along the line A-A direction of FIG. 3 . The outline of an electric power steering apparatus 80 will be described with reference to FIGS. 1 to 5 . In the following description, a front of the vehicle when the electric power steering apparatus 80 is attached to the vehicle is simply described as a front and a rear of the vehicle when the electric power steering apparatus 80 is attached to the vehicle is simply described as a rear.

<Electric Power Steering Apparatus>

In the order in which a force is transmitted by a driver (operator), the electric power steering apparatus 80 includes a steering wheel 81 , a steering shaft 82 , a steering force assisting mechanism 83 , an universal joint 84 , a lower shaft 85 , an universal joint 86 , a pinion shaft 87 , a steering gear 88 , and a tie rod 89 . In addition, the electric power steering apparatus 80 includes an ECU (Electronic Control Unit) 90 and a torque sensor 91 a . A vehicle speed sensor 91 b is provided in the vehicle and inputs a vehicle speed signal V to the ECU 90 using a CAN (Controller Area Network) communication.

The steering shaft 82 includes an input shaft 82 a and an output shaft 82 b . One end of the input shaft 82 a is connected to the steering wheel 81 and the other end thereof is connected to the steering force assisting mechanism 83 through the torque sensor 91 a . One end of the output shaft 82 b is connected to the steering force assisting mechanism 83 and the other end thereof is connected to the universal joint 84 . In this embodiment, the input shaft 82 a and the output shaft 82 b are formed of a magnetic material such as iron.

One end of the lower shaft 85 is connected to the universal joint 84 and the other end thereof is connected to the universal joint 86 . One end of the pinion shaft 87 is connected to the universal joint 86 and the other end thereof is connected to the steering gear 88 .

The steering gear 88 includes a pinion 88 a and a rack 88 b . The pinion 88 a is connected to the pinion shaft 87 . The rack 88 b is engaged with the pinion 88 a . The steering gear 88 is constituted as a rack-and-pinion type. The steering gear 88 converts a rotational motion transmitted to the pinion 88 a into a linear motion with the rack 88 b . The tie rod 89 is connected to the rack 88 b.

The steering force assisting mechanism 83 includes a reduction gear 92 and an electric motor (motor) 70 . Further, the electric motor 70 is a so-called brushless motor which is described as an example, but the electric motor 70 may be an electric motor provided with a brush (slider) and a commutator. The reduction gear 92 is connected to the output shaft 82 b . The electric motor 70 is an electric motor connected to the reduction gear 92 and for generating auxiliary steering torque. In the electric power steering apparatus 80 , the steering shaft 82 , the torque sensor 91 a , and the reduction gear 92 form a steering column. The electric motor configured 70 provides the auxiliary steering torque to the output shaft 82 b of the steering column. That is, the electric power steering apparatus 80 according to this embodiment is a column assist system.

As illustrated in FIG. 2 , the steering force assisting mechanism 83 of the electric power steering apparatus 80 includes a steering column 50 and a steering bracket 52 , referred to as an upper attachment bracket functions, as a mechanism for supporting each parts such as the ECU 90 and the electric motor 70 . The steering column 50 rotatably supports the input shaft 82 a . The steering column 50 has a double tube structure constituted by an outer column 51 and an inner column 54 which absorb impact energy at the time of collapse and secure a predetermined collapse contract at a coupling portion to the reduction gear 92 .

The steering bracket 52 is disposed on an upper side of the outer column 51 in a vertical direction. The steering bracket 52 is attached to a vehicle body and supports the outer column 51 . The steering bracket 52 includes an attachment plate portion 52 b , a frame-shaped support portion 52 a formed integrally with the attachment plate portion 52 b , and a tilt mechanism constituted to support the outer column 51 . The attachment plate portion 52 b of the steering bracket 52 is provided with a capsule support portion 59 extending to the outside from the outer column 51 . The tilt mechanism is formed in the frame-shaped support portion 52 a . The steering bracket 52 is fixed to a steering bracket supporting apparatus 10 (hereinafter, referred to as a supporting apparatus 10 ) so that the steering bracket 52 is supported by a vehicle body-side member 21 illustrated in FIG. 5 .

The supporting state is released by an operation of rotating a tilt lever 53 of the tilt mechanism. By this operation, it is possible to adjust a tilt position of the steering column 50 upward and downward.

The torque sensor 91 a illustrated in FIG. 1 detects a steering force by the driver, transmitted to the input shaft 82 a through the steering wheel 81 , as steering torque. The vehicle speed sensor 91 b detects a running speed (vehicle speed) of the vehicle on which the electric power steering apparatus 80 is mounted. The ECU 90 is electrically connected to the electric motor 70 , the torque sensor 91 a , and the vehicle speed sensor 91 b.

<Control Unit: ECU>

The ECU 90 controls the operation of the electric motor 70 . In addition, the ECU 90 acquires a signal from each of the torque sensor 91 a and the vehicle speed sensor 91 b . In other words, the ECU 90 acquires steering torque T from the torque sensor 91 a , and acquires a vehicle speed signal V of the vehicle from the vehicle speed sensor 91 b . Power is supplied to the ECU 90 from a power supply unit (for example, buttery on the vehicle) 99 when an ignition switch 98 is turned ON. The ECU 90 calculates an auxiliary steering command value for an assist command, based on the steering torque T and the vehicle speed signal V. Then, the ECU 90 adjusts a power value X to be supplied to the electric motor 70 based on the calculated auxiliary steering command value. From the electric motor 70 , the ECU 90 acquires information of an inductive voltage or rotation information of a rotor such as a resolver to be described below, as operation information Y.

The steering force by a steerer (driver) input to the steering wheel 81 is transmitted to the reduction gear 92 in the steering force assisting mechanism 83 through the input shaft 82 a . At this time, the ECU 90 acquires the steering torque T, which is input to the input shaft 82 a , from the torque sensor 91 a and acquires the vehicle speed signal V from the vehicle speed sensor 91 b . Then, the ECU 90 controls the operation of the electric motor 70 . The auxiliary steering torque generated by the electric motor 70 is transmitted to the reduction gear 92 .

The steering torque (including the auxiliary steering torque) output through the output shaft 82 b is transmitted to the lower shaft 85 through the universal joint 84 and is further transmitted to the pinion shaft 87 through the universal joint 86 . The steering force transmitted to the pinion shaft 87 is transmitted to the tie rod 89 through the steering gear 88 , thereby causing the steering wheel to turn.

(Supporting Apparatus)

A separation capsule 11 illustrated in FIGS. 3 to 5 is formed by aluminum die-casting. The separation capsule 11 is provided with a capsule attachment hole 11 h (see FIGS. 3 and 4 ) constituted to fix the separation capsule 11 to the vehicle body-side member 21 with a bolt 22 and a nut 23 illustrated in FIG. 5 . In addition, the separation capsule 11 has three resin injection holes 12 h (first capsule-side hole) communicated with resin injection holes 59 h (first bracket-side hole) provided at a capsule support portion 59 of the steering bracket 52 , and a resin member 12 P straddles the resin injection hole 59 h and the resin injection hole 12 h in a state before the separation.

The resin member 12 P is a mechanical fuse constituted to be fractured during a secondary collision by shearing force applied to the resin member 12 P which is injected into the resin injection hole 12 h of the separation capsule 11 . A separation load causing the fracture of the resin member 12 P depends on the material and the sheared cross-sectional area of the resin member 12 P. Even when some of the resin member 12 P is cut and thus the set value of the separation load, at which the steering column moves in the front of the vehicle, is lowered, a shear pin 13 according to the first embodiment straddles a second bracket-side hole 59 I and a second capsule-side hole 11 J in the state before the separation so as to withstand impact of, for example, an telescopic operation in an ordinary use. The ordinary use includes a condition where inertial or impact is applied due to acceleration and deceleration during a driving operation.

In the ordinary use, when a load is applied to the steering column, which is attached to the vehicle, by the impact of, for example, telescopic operation, if the steering column is pushed to the front of the vehicle, the resin member 12 P is subjected to the shearing force and the shearing force is similarly applied to the shear pin 13 . Thus, the fracture of the resin member 12 P is suppressed and the malfunction is suppressed during the ordinary use.

The shear pin 13 may be made of the same resin as the resin member 12 P or be made of a metal. When the shear pin 13 is formed of the resin, the shear pin 13 is fractured simultaneously with the resin member 12 P and thus the steering bracket 52 can be separated from the separation capsule 11 fixed to the vehicle body-side member 21 when a considerable load, which an operation of an inertial action body to be described below does not catch up with, is applied in a short time.

As illustrated in FIG. 5 , the shear pin 13 includes a cylindrical shear pin body 13 B, a head portion 13 P which is provided at one end of the shear pin body 13 B and has a diameter larger than that of the shear pin body 13 B, and a hook portion 13 T which is provided at the other end of the shear pin body 13 B and is positioned at an edge of the second bracket-side hole 59 I of the capsule support portion 59 . The hook portion 13 T, having the diameter larger than that of the shear pin body 13 B and a thickness smaller than that of the head portion 13 P, has a fragile structure.

An inertial action body 15 is clamped and fixed between the head portion 13 P of the shear pin 13 and the surface of the separation capsule 11 . FIG. 6 is a perspective view schematically illustrating the inertial action body according to the first embodiment. As illustrated in FIGS. 5 and 6 , the inertial action body 15 has a shape like a head of a nail puller. The inertial action body 15 includes a base portion 15 B and two-pronged claw portions 15 F and 15 F obtained by dividing a part of the base portion 15 B with a slit 15 M. The claw portions 15 F and 15 F have an inclined surface or a curved surface such that the distance from the surface of the separation capsule 11 increases toward the base portion 15 B. Thus, the inertial action body 15 can convert the inertial action applied thereto to an action to pull out the shear pin 13 from the second bracket-side hole 59 I. The shear pin 13 penetrates into the slit 15 M, and the head portion 13 P comes in contact with a surface 15 Q of the claw portion 15 F. As a result, as described above, the inertial action body 15 is clamped between the head portion 13 P of the shear pin 13 and the surface of the separation capsule 11 , and a sliding contact surface 15 U of inertial action body 15 is firmly adhered to the separation capsule 11 . Therefore, frictional force is generated between the sliding contact surface 15 U of the inertial action body 15 and the separation capsule 11 , so that the movement of the inertial action body 15 is set to be suppressed for a relatively weak impact.

As illustrated in FIG. 6 , in the inertial action body 15 , a weight portion 15 G is inserted into a hole 15 H such that the center of gravity of the inertial action body 15 gathers to the base portion 15 B. Thus, it is possible to set a set value of an operation load in which the inertial action body 15 operates. In the first embodiment, the inertial action body 15 is provided with the weight portion 15 G separately from the base portion 15 B, but may be a weight portion in which the center of gravity of the inertial action body 15 gathers due to the material, the shape, and the like of the base portion 15 B. The weight portion 15 G biases the center of gravity of the inertial action body 15 toward the base portion 15 B.

As illustrated in FIG. 6 , in the inertial action body 15 , the base portion 15 B and the claw portions 15 F are made of an iron material such as stainless steel and the weight portion 15 G is made of a material such as tungsten carbide having a larger specific gravity than the base portion 15 B.

FIG. 7 is a schematic cross-sectional view illustrating a state where the shear pin is pulled out in the supporting apparatus for the steering bracket according to the first embodiment. For example, when an impact such as a primary collision of the vehicle, which exceeds the set value of the operation load in which the inertial action body 15 operates, is applied to the supporting apparatus 10 , the inertial action body 15 moves in a direction F toward the front of the vehicle. The head portion 13 P of the shear pin 13 moves along the surface 15 Q and the hook portion 13 T illustrated in FIG. 5 is broken. Alternatively, the hook portion 13 T is deformed to become an end 13 Tk to be drawn into the second bracket-side hole 59 I and the second capsule-side hole 11 J, and is pulled out from the second bracket-side hole 59 I as the inertial action body 15 moves. As a result, the shear pin body 13 B of the shear pin 13 drops or is pulled out from the second bracket-side hole 59 I in a direction Fu as the inertial action body 15 moves. Thus, the weight portion 15 G moves to the front of the vehicle by the inertia due to the primary collision, and thus the shear pin 13 can be pulled out from the second bracket-side hole 59 I with the movement of the weight portion 15 .

FIG. 8 is a schematic cross-sectional view illustrating a state after the supporting apparatus for the steering bracket according to the first embodiment is separated. Subsequently, when an excessive load which exceeds a load set value of the secondary collision is applied to the steering column 50 attached to the vehicle, and the steering column 50 is pushed in the direction F toward the front of the vehicle, a part of the resin member 12 P is cut into a resin piece 12 Pk and a resin piece 12 Pkk. Therefore, the steering column 50 moves to the front of the vehicle to separate the capsule support portion 59 from the separation capsule 11 , and the supporting apparatus 10 protects the driver (operator) from a thrust (secondary collision) of a steering wheel.

As described above, the supporting apparatus 10 includes the capsule support portion 59 of the steering bracket 52 supporting the steering column 50 , and the separation capsule 11 to fix the vehicle body-side member 21 and the steering bracket 52 . The capsule support portion 59 includes the first capsule-side hole 12 h and the second capsule-side hole 11 J opened thereon, and the separation capsule 11 includes the first bracket-side hole 59 h and the second bracket-side hole 59 I opened thereon. The resin member 12 P is arranged at a position straddling the first bracket-side hole 59 h and the first capsule-side hole 12 h before the separation. The shear pin 13 is arranged at a position straddling the second bracket-side hole 59 I and the second capsule-side hole 11 J before the separation. The inertial action body 15 moves separately from the steering column by the action of inertia applied independently to the inertial action body 15 and the shear pin 13 can be pulled out from the second bracket-side hole 59 I with the movement of the inertial action body 15 .

For this reason, when the load is applied to the steering column 50 , which is attached to the vehicle, by the impact in the ordinary use, if the steering column 50 is pushed in the direction F toward the front of the vehicle, the resin member 12 P is subjected to the shearing force and the shearing force is similarly applied to the shear pin 13 . Thus, the fracture of the resin member 12 P is suppressed and the malfunction is suppressed during the ordinary use.

When the excessive load which exceeds the load set value of the secondary collision is applied to the steering column attached to the vehicle and the steering column 50 is pushed in the Direction F toward the front of the vehicle, the inertial action body 15 moves and the shear pin 13 is pulled out from the second bracket-side hole 59 I with the movement of the inertial action body 15 . Thereafter, some of the resin member 12 P is cut into the resin piece 12 Pk and the resin piece 12 Pkk, the steering column thus moves to the front of the vehicle to make the state where the capsule support portion 59 is separated from the separation capsule 11 , and the supporting apparatus 10 alleviates the impact caused by the collision (secondary collision) of the driver (operator) with the steering wheel. As a result, a part of the supporting structure is cut, which causes lowering of the set value of the separation load at which the steering column 50 moves in the Direction F toward the front of the vehicle, therefore the supporting apparatus 10 can further protect an operator who is light in weight.

The inertial action body 15 according to the first embodiment is fixed to the separation capsule 11 side, but may be fixed to the capsule support portion 59 side. The electric power steering apparatus 80 (steering apparatus) is supported by the supporting apparatus 10 described above. Thus, a part of the supporting structure is cut, which causes lowering of the set value of the separation load at which the steering column 50 moves to the front of the vehicle, therefore the steering apparatus can further protect the operator who is light in weight.

Second Embodiment

FIG. 9 is a schematic cross-sectional view illustrating a state before a supporting apparatus for a steering bracket according to a second embodiment is separated. FIG. 10 is a schematic cross-sectional view illustrating a state a shear pin of the supporting apparatus for the steering bracket according to the second embodiment is pulled out. The same members as those described above are denoted by the same reference numerals and the description thereof will not be presented to avoid duplication. As illustrated in FIGS. 9 and 10 , with respect to a second bracket-side hole 59 I and a second capsule-side hole 11 J, one of the second bracket-side hole 59 I and the second capsule-side hole 11 J, which is located near the head portion 13 P of the shear pin 13 , has a larger diameter than the other. For example, the second capsule-side hole 11 J has the larger diameter than the second bracket-side hole 59 I. Thus, as illustrated in FIG. 9 , the second capsule-side hole 11 J holds the posture of the shear pin body 13 B before the separation. For example, when impact such as a primary collision of the vehicle, which exceeds a set value of an operation load in which an inertial action body 15 operates, is applied to the supporting apparatus 10 , the inertial action body 15 moves in a direction F toward a front of a vehicle. The head portion 13 P of the shear pin 13 moves along a surface 15 Q and a hook portion 13 T illustrated in FIG. 9 is broken. Alternatively, the shear pin 13 is deformed to have an end 13 Tk, thereby being drawn into the second bracket-side hole 59 I and the second capsule-side hole 11 J and being pulled out from the second bracket-side hole 59 I as the inertial action body 15 moves. As a result, the shear pin body 13 B of the shear pin 13 drops or is pulled out from the second bracket-side hole 59 I in a direction Fu as the inertial action body 15 moves. In this case, as illustrated in FIG. 10 , with respect to the relation between the surface 15 Q and the head portion 13 P, when the surface 15 Q has an inclined surface or a curved surface, the head portion is not necessarily pulled out parallel to the direction Fu. As in the second embodiment, when the second capsule-side hole 11 J has a larger diameter than the second bracket-side hole 59 I, it is possible to increase the probability of the pulling-out even when the posture of the shear pin body 13 B is inclined.

Third Embodiment

FIG. 11 is a schematic cross-sectional view illustrating a state before a supporting apparatus for a steering bracket according to a third embodiment is separated. The same members as those described above are denoted by the same reference numerals and the description thereof will not be presented to avoid duplication. As illustrated in FIG. 11 , a guide surface 59 G is provided on the surface of a capsule support portion 59 or a separation capsule 11 of a steering bracket to guide a movement direction of an inertial action body 15 due to action of inertia. For example, even when a moment load including a rotational component is applied to a weight portion 15 G, a shear pin 13 can be pulled out along the guide surface 59 G by the inertial action body 15 .

Fourth Embodiment

FIG. 12 is a schematic cross-sectional view illustrating a state before a supporting apparatus for a steering bracket according to a fourth embodiment is separated. The same members as those described above are denoted by the same reference numerals and the description thereof will not be presented to avoid duplication. As illustrated in FIG. 12 , a shear pin 13 according to the fourth embodiment includes a cylindrical shear pin body 13 B, a head portion 13 P which is provided at one end of the shear pin body 13 B and has a diameter larger than that of the shear pin body 13 B, and a hook portion 13 TF which is provided at the other end of the shear pin body 13 B and is positioned at an edge of a second bracket-side hole 59 I of a capsule support portion 59 . A hollow portion 13 S with a bottom is opened in the shear pin body 13 B and elastic force is urged to the outside of a hook portion 13 TF. Therefore, the shear pin 13 according to the fourth embodiment is constituted such that the diameter of the hook portion 13 TF facilely decreases and it is possible to pull out the shear pin 13 without breakage.

Fifth Embodiment

FIG. 13 is a plan view schematically illustrating a supporting apparatus for a steering bracket constituted to attach a steering column to a vehicle. FIG. 14 is a perspective view schematically illustrating a portion constituted to attach the steering column to the vehicle. FIG. 15 is a perspective view schematically illustrating a portion constituted to attach a steering column according to a fifth embodiment to the vehicle. FIG. 15 is a cross-sectional view as viewed in the line B-B direction of FIG. 13 . FIG. 16 is a schematic cross-sectional view illustrating a state before a supporting apparatus for a steering bracket according to the fifth embodiment is separated. The same members as those described above are denoted by the same reference numerals and the description thereof will not be presented to avoid duplication. A separation capsule 11 illustrated in FIGS. 13 to 16 is formed by aluminum die-casting. The separation capsule 11 is provided with a capsule attachment hole 11 h (see FIGS. 3 and 15 ) constituted to fix a separation capsule 11 to a vehicle body-side member 21 with a bolt 22 and a nut 23 illustrated in FIG. 16 . In addition, the separation capsule 11 has three resin injection holes 12 h (first capsule-side hole) communicated with resin injection holes 59 h (first bracket-side hole) provided at a capsule support portion 59 of the steering bracket, and a resin member 12 P straddles the resin injection hole 59 h and the resin injection hole 12 h in a state before the separation.

The resin member 12 P injected into the resin injection hole 12 h of the separation capsule 11 is a mechanical fuse constituted to be fractured by shearing force applied during a secondary collision. A separation load causing the fracture of the resin member 12 P depends on the material and the sheared cross-sectional area of the resin member 12 P. Even when a part of the resin member 12 P is cut causing lowering of the set value of the separation load at which the steering column moves in the front of the vehicle, a shear pin 13 D according to the fifth embodiment straddles a second bracket-side hole 11 I and the second capsule-side hole 11 J in the state before the separation so as to withstand impact of, for example, an telescopic operation in an ordinary use. The ordinary use includes a condition where inertial or impact is applied due to acceleration and deceleration during a driving operation.

When a load is applied to the steering column 50 , which is attached to the vehicle, by the impact of, for example, telescopic operation in the ordinary use, if the steering column 50 is pushed to the front of the vehicle, the resin member 12 P is subjected to the shearing force and the shearing force is similarly applied to the shear pin 13 D. Thus, the fracture of the resin member 12 P is suppressed and the malfunction is suppressed during the ordinary use.

The shear pin 13 D may be made of the same resin as the resin member 12 P and be made of a metal. When the shear pin 13 D is formed of the resin, the shear pin 13 D is fractured simultaneously with the resin member 12 P and thus the steering bracket 52 can be separated from the separation capsule 11 fixed to the vehicle body-side member 21 , when a considerable load is applied in a short time such that an operation of a cam mechanism to be described below does not catch up with the considerable load.

As illustrated in FIG. 16 , the shear pin 13 D includes a head portion 13 P which is provided at one end of a shear pin body of solid cylindrical body and has a diameter larger than that of the shear pin body. A pin tip 13 PT which is the other end of the shear pin body of the shear pin 13 D is inserted into the second bracket-side hole 11 I of the capsule support portion 59 in the state before the separation and is positioned in a cam mechanism 13 A. The pin tip 13 PT may be penetrated through the second bracket-side hole 11 I.

The cam mechanism 13 A includes a cam rotor 13 CM interlocking with the shear pin 13 D, and a cam stator 13 CF fixed to the capsule support portion 59 or the separation capsule 11 of the steering bracket. FIG. 17 is a perspective view schematically illustrating protrusion portions of the cam rotor of the cam mechanism according to the fifth embodiment. As illustrated in FIG. 17 , the cam rotor 13 CM has protrusion portions 13 Q on a surface facing the cam stator 13 CF. The cam stator 13 CF has protrusion portions 13 FB, which are similar to the protrusion portions 13 Q illustrated in FIG. 17 , on a surface facing the cam rotor 13 CM. Since the protrusion portions 13 FB of the cam stator 13 CF are located at recessed portions between the protrusion portions 13 Q of the cam rotor 13 CM, and the protrusion portions 13 Q and the protrusion portions 13 FB have the similar height, the protrusion portions 13 Q and the protrusion portions 13 FB are engaged with each other. When the cam rotor 13 CM rotates relative to the cam stator 13 CF, as illustrated in FIG. 18 , the phase of the protrusion portions 13 Q coincides with that of the protrusion portions 13 FB. In this case, since the protrusion portions 13 Q ride over the protrusion portions 13 FB, the distance between the cam rotor 13 CM and the cam stator 13 CF increases. The shear pin 13 D penetrates a lever member 13 L to be described below and a washer 13 w , and the head portion 13 P is supported by the washer 13 w . For this reason, the distance between the cam rotor 13 CM and the cam stator 13 CF increases depending on the rotation amount of the cam rotor 13 CM which rotates relative to the cam stator 13 CF. An insertion length of the shear pin 13 D to be inserted into the second bracket-side hole 11 I varies depending on the distance between the cam rotor 13 CM and the cam stator 13 CF. Thus, the cam mechanism 13 A can convert the rotation motion, which depends on the amount of rotation due to the inertial action, to a motion in which the shear pin 13 D is pulled out from the second bracket-side hole 11 I.

The lever member 13 L is a rod-shaped member which rotates interlocking with the rotation of the cam rotor 13 CM. Since the lever member 13 L applies the load to a part of the cam rotor 13 CM, the lever member 13 L is a member which is used to move the center of gravity of the cam rotor toward the outside from a rotation center of the cam rotor 13 CM. Thus, it is possible to set a set value of an operation load in which the cam mechanism 13 A operates. The lever member 13 L is provided with a weight portion 13 W at a side far from the cam rotor 13 CM. The weight portion 13 W is made of a material such as tungsten carbide having a larger specific gravity than the cam rotor 13 CM. This makes it possible to increase the amount of movement of the center of gravity toward the outside from the rotation center of the cam rotor 13 CM. In this way, the weight portion 13 W allows the center of gravity of the lever member 13 L to be biased toward the outside from the rotation center of the cam rotor 13 CM.

As illustrated in FIG. 16 , the lever member 13 L is disposed in a direction orthogonal to the front of the vehicle when the surface of the separation capsule 11 is viewed in a plan view. For example, when impact such as a primary collision of the vehicle, which exceeds the set value of the operation load in which the lever member 13 L rotates, is applied to the supporting apparatus 10 , the lever member 13 L of the cam mechanism 13 A rotates in a direction FR toward the front of the vehicle. The distance between the cam rotor 13 CM and the cam stator 13 CF increases depending on the rotation amount of the cam rotor 13 CM which rotates relative to the cam stator 13 CF. The insertion amount of the shear pin 13 D to be inserted into the second bracket-side hole 11 I decreases with the movement of the cam rotor 13 CM. As a result, as illustrated in FIG. 18 , the shear pin 13 D is pulled out from the second bracket-side hole 11 I with the movement of the cam rotor 13 CM.

FIG. 19 is a schematic cross-sectional view illustrating a state after the supporting apparatus for the steering bracket according to the fifth embodiment is separated. Subsequently, when an excessive load exceeding a load set value of the secondary collision is applied to the steering column attached to the vehicle and the steering column is pushed to the front of the vehicle, a part of the resin member 12 P is cut into a resin piece 12 Pk and a resin piece 12 Pkk, the steering column moves to the front of the vehicle to make the state where the capsule support portion 59 is separated from the separation capsule 11 , and the supporting apparatus 10 alleviates the impact caused by the collision (secondary collision) of the driver (operator) with the steering wheel.

As described above, the supporting apparatus 10 includes the capsule support portion 59 of the steering bracket 52 , which supports the steering column 50 , and the separation capsule 11 to fix the vehicle body-side member 21 and the steering bracket, and the capsule support portion 59 includes the first capsule-side hole 12 h and the second capsule-side hole 11 J opened thereon, and the separation capsule 11 includes the first bracket-side hole 59 h and the second bracket-side hole 11 I opened thereon. The shear pin 13 D is arranged at a position straddling the first bracket-side hole 59 h and the first capsule-side hole 12 h before the separation. The resin member 12 P is arranged at a position straddling the second bracket-side hole 11 I and the second capsule-side hole 11 J before the separation. In the supporting apparatus 10 , the cam mechanism 13 A rotates by the action of inertia. That is, the weight portion 13 W rotates around the shear pin 13 D by the inertia due to the primary collision and moves to the front of the vehicle. The shear pin 13 D can be pulled out from the second bracket-side hole 11 I with the rotation of the cam mechanism 13 A.

For this reason, when the load due to the impact during the ordinary use is applied to the steering column 50 attached to the vehicle, if the steering column 50 is pushed to the front of the vehicle, the resin member 12 P is subjected to the shearing force, and the shearing force is similarly applied to the shear pin 13 D. Thus, the fracture of the resin member 12 P is suppressed and the malfunction is suppressed during the ordinary use.

When the excessive load exceeding the load set value of the secondary collision is applied to the steering column attached to the vehicle and the steering column 50 is pushed in the direction F toward the front of the vehicle, since the cam mechanism 13 A rotates by the action of inertia and the shear pin 13 D is pulled out from the second bracket-side hole 11 I with the rotation of the cam mechanism 13 A, a part of the resin member 12 P is cut into the resin piece 12 Pk and the resin piece 12 Pkk, the steering column thus moves to the front of the vehicle to make the state where the capsule support portion 59 is separated from the separation capsule 11 , and the supporting apparatus 10 alleviates the impact caused by the collision (secondary collision) of the driver (operator) with the steering wheel. As a result, a part of the supporting structure is cut, which lowers the set value of the separation load at which the steering column 50 moves in the direction F toward the front of the vehicle, so that the supporting apparatus 10 can further protect an operator who is light in weight.

The cam mechanism 13 A according to the fifth embodiment is fixed to the surface of the capsule support portion 59 , but may be fixed to the separation capsule 11 side. An electric power steering apparatus 80 (steering apparatus) is supported by the supporting apparatus 10 described above. Thus, a part of the supporting structure is cut, which lowers the set value of the separation load at which the steering column 50 moves to the front of the vehicle, so that the steering apparatus can further protect the operator who is light in weight.

Sixth Embodiment

FIG. 20 is a schematic cross-sectional view illustrating a state before a supporting apparatus for a steering bracket according to a sixth embodiment is separated. The same members as those described above are denoted by the same reference numerals and the description thereof will not be presented to avoid duplication. As illustrated in FIG. 20 , the function of the cam rotor 13 CM according to the fifth embodiment may be integrated with a lever member 13 L. The lever member 13 L is provided with protrusion portions 13 Q. The lever member 13 L may be integrated with or fixed to a head portion 13 P of a shear pin 13 D.

Seventh Embodiment

FIG. 21 is a schematic cross-sectional view illustrating a state before a supporting apparatus for a steering bracket according to a seventh embodiment is separated. FIG. 22 is a schematic diagram of a washer of the supporting apparatus for the steering bracket according to the seventh embodiment. The same members as those described above are denoted by the same reference numerals and the description thereof will not be presented to avoid duplication. As illustrated in FIG. 21 , the function of the cam rotor 13 CM according to the fifth embodiment may be integrated with a washer 13 w . As illustrated in FIG. 22 , the washer 13 w is provided with protrusion portions 13 Q which are bendable by a slit. The protrusion portions 13 Q are cut and raised, and thus the washer 13 w protrudes toward a protrusion portion 13 FB of the lever member 13 L.

10 SUPPORTING APPARATUS

11 SEPARATION CAPSULE

11 h CAPSULE ATTACHMENT HOLE

11 J SECOND CAPSULE-SIDE HOLE

12 h RESIN INJECTION HOLE (FIRST CAPSULE-SIDE HOLE)

12 P RESIN MEMBER

12 Pk, 12 Pkk RESIN PIECE

13 , 13 D SHEAR PIN

13 A CAM MECHANISM

13 B SHEAR PIN BODY

13 CF CAM STATOR

13 CM CAM ROTOR

13 L LEVER MEMBER

13 P HEAD PORTION

13 PT PIN TIP

13 Q PROTRUSION PORTION

13 FB PROTRUSION PORTION

13 T HOOK PORTION

13 TF HOOK PORTION

13 S HOLLOW PORTION

13 W WEIGHT PORTION

13 w WASHER

15 INERTIAL ACTION BODY

15 M SLIT

15 B BASE PORTION

15 H HOLE

15 G WEIGHT PORTION

15 U SLIDING CONTACT SURFACE

15 F CLAW PORTION

15 Q SURFACE

21 VEHICLE BODY-SIDE MEMBER

22 BOLT

23 NUT

50 STEERING COLUMN

51 OUTER COLUMN

52 STEERING BRACKET

53 TILT LEVER

54 INNER COLUMN

59 CAPSULE SUPPORT PORTION

59 h RESIN INJECTION HOLE (FIRST BRACKET-SIDE HOLE)

59 I, 11 I SECOND BRACKET-SIDE HOLE

70 ELECTRIC MOTOR

80 ELECTRIC POWER STEERING APPARATUS

81 STEERING WHEEL

82 STEERING SHAFT

82 a INPUT SHAFT

82 b OUTPUT SHAFT

83 STEERING FORCE ASSISTING MECHANISM

84 UNIVERSAL JOINT

85 LOWER SHAFT

86 UNIVERSAL JOINT

87 PINION SHAFT

88 STEERING GEAR

88 a PINION

88 b RACK

89 TIE ROD

90 ECU

91 a TORQUE SENSOR

91 b VEHICLE SPEED SENSOR

92 REDUCTION GEAR

98 IGNITION SWITCH

99 POWER SUPPLY UNIT