1. Field of the Invention
The invention relates to a steering column apparatus for a vehicle. More specifically, the invention relates to a steering column apparatus for a vehicle, which includes a steering column that holds a steering wheel in a manner such that the steering wheel is rotatable, the steering column including a lower tube connected to a portion of a vehicle body through a housing of a power steering actuator; and an upper tube which is connected to the lower tube to be slidable in a direction of an axis of the steering column, which is telescopic, and which is connected to the portion of the vehicle body through a bracket.
2. Description of the Related Art
For example Japanese Patent Application Publication No. 2006-36077 (JP-A-2006-36077) describes the steering column apparatus for a vehicle, which has the above-described configuration. In the steering column apparatus for a vehicle described in the publication No. 2006-36077, the housing is tiltable in upward and downward directions with respect to the portion of the vehicle body; a rear end portion of the housing is integrated with a lower end portion of the lower tube by fitting the rear end portion of the housing into the lower end portion of the lower tube; and the upper tube is moved toward a front side of the vehicle with respect to the portion of the vehicle body, when a load equal to or above a predetermined value is applied to the upper tube.
In the steering column apparatus for a vehicle described in the publication No. 2006-36077, a bending moment occurs in a fitting portion where the rear end portion of the housing is fitted into the lower end portion of the lower tube, due to the load (secondary collision load) toward the front side of the vehicle, which is applied to an upper end portion of the steering column from an occupant. Therefore, the rear end portion of the housing pivots downward around a tilt center of the housing, and the lower end portion of the lower tube pivots downward so that the lower end portion of the lower tube is disconnected from the rear end portion of the housing. As a result, the lower end portion of the lower tube may be broken or disconnected from the rear end portion of the housing. Accordingly, the upper tube may not be appropriately moved in a direction of an axis of the steering column.
An aspect of the invention relates to a steering column apparatus for a vehicle, which includes a steering column that holds a steering wheel in a manner such that the steering wheel is rotatable. The steering column includes: a housing of a power steering actuator, which is tiltable in upward and downward directions with respect to a portion of a vehicle body; a lower tube connected to the portion of the vehicle body through the housing, wherein a rear end portion of the housing in a longitudinal direction of a vehicle is integrated with a lower end portion of the lower tube; an upper tube connected to the lower tube to be slidable in a direction of an axis of the steering column, wherein the upper tube is telescopic, the upper tube is connected to the portion of the vehicle body through a bracket, and the upper tube is moved toward a front side of the vehicle with respect to the portion of the vehicle body when a load equal to or above a predetermined value is applied to the upper tube; and a reinforcement portion provided only in a bottom portion of an area where the rear end portion of the housing is integrated with the lower end portion of the lower tube.
In this aspect, the rear end portion of the housing may be integrated with the lower end portion of the lower tube by fitting the rear end portion of the housing to the lower end portion of the lower tube; and the reinforcement portion may restrict movement of the rear end portion of the housing and the lower end portion of the lower tube away from each other. Also, the rear end portion of the housing may be integrated with the lower end portion of the lower tube by integrally forming the housing and the lower tube; and the reinforcement portion may be configured using a reinforcement rib that extends in the direction of the axis of the steering column. In this case, a distance between an upper end of the reinforcement rib and a lower end of the upper tube may be equal to or longer than a predetermined distance so that the upper tube is movable the predetermined distance. Also, the rear end portion of the housing may be integrated with the lower end portion of the lower tube by integrally forming the housing and the lower tube; and the reinforcement portion may be formed by forming an inner hole of the lower tube in a manner such that a center of the inner hole is offset upward from an axis of the lower tube by a predetermined amount in a direction perpendicular to the axis of the lower tube.
In the above-described aspect, the rear end portion of the housing may be integrated with the lower end portion of the lower tube by fitting the rear end portion of the housing into the lower end portion of the lower tube; and the reinforcement portion may be configured using a screw. The rear end portion of the housing may be integrated with the lower end portion of the lower tube by fitting the lower end portion of the lower tube into the rear end portion of the housing; and the reinforcement portion may be configured using a screw.
The rear end portion of the housing may be integrated with the lower end portion of the lower tube by fitting the rear end portion of the housing into the lower end portion of the lower tube; and the reinforcement portion may be configured using a hook formed in a bottom portion of the lower end portion of the lower tube, and the hook may be pressed into an engagement hole formed in the rear end portion of the housing.
The steering column apparatus may further include a retention ring removably fitted to an outer periphery of the lower end portion of the lower tube; the rear end portion of the housing may be integrated with the lower end portion of the lower tube by fitting the rear end portion of the housing into the lower end portion of the lower tube;
the reinforcement portion may be configured using a pin that is integrally formed in a lower portion of the retention ring, and the pin may be fitted into a through-hole formed in a bottom portion of the lower end portion of the lower tube, and a through-hole formed in a bottom portion of the rear end portion of the housing. The retention ring may include a lower semicircular ring, an upper semicircular ring, and a pair of bolts that connects the lower semicircular ring to the upper semicircular ring; and the pin may be integrally formed in the lower semicircular ring.
In the steering column apparatus for a vehicle according to the invention, the reinforcement portion is provided only in the bottom portion of the area where the rear end portion of the housing is integrated with the lower end portion of the lower tube. The portion where the reinforcement portion is provided (i.e., the bottom portion of the above-described area) is pulled due to a bending moment, and is more likely to be displaced and deformed than a top portion of the above-described area (i.e., the portion compressed due to the bending moment). Accordingly, in the invention, displacement and deformation due to the bending moment are made less likely to occur by the reinforcement portion, and the weight is reduced as compared to the case where the entire area is reinforced. As a result, it is possible to effectively suppress the displacement and deformation of the lower end portion of the lower tube. Thus, the upper tube is appropriately moved in the direction of the axis of the steering column with respect to the lower tube.
Another aspect of the invention relates to a steering column apparatus for a vehicle, which includes a steering column that holds a steering wheel in a manner such that the steering wheel is rotatable. The steering column includes: a housing of a power steering actuator, which is tiltable in upward and downward directions with respect to a portion of a vehicle body; a lower tube connected to the portion of the vehicle body through the housing, wherein a rear end portion of the housing in a longitudinal direction of a vehicle is integrated with a lower end portion of the lower tube; an upper tube connected to the lower tube to be slidable in a direction of an axis of the steering column, wherein the upper tube is telescopic, the upper tube is connected to the portion of the vehicle body through a bracket, and the upper tube is moved toward a front side of the vehicle with respect to the portion of the vehicle body when a load equal to or above a predetermined value is applied to the upper tube; and a reinforcement portion provided in a bottom portion of an area where the rear end portion of the housing is integrated with the lower end portion of the lower tube.
The foregoing and further objects, features and advantages of the invention will become apparent from the following description of example embodiments with reference to the accompanying drawings, wherein like numerals are used to represent like elements and wherein:
Hereinafter, each embodiment of the invention will be described with reference to the drawings. Each of
The steering force is input to the transmission shaft CO through the steering wheel SH, and the transmission shaft CO transmits the input steering force to the right and left front wheels (not shown). The transmission shaft CO includes a steering main shaft 10 in a steering column SC; an intermediate shaft (not shown) connected to the steering main shaft 10 through an upper universal joint (not shown); a pinion shaft (not shown) connected to the intermediate shaft through a lower universal joint (not shown); a rack bar (not shown) connected to the pinion shaft through a pinion gear (not shown) and a rack gear (not shown); and a pair of right and left tie rods (not shown). The right and left tie rods are connected to respective right and left end portions of the rack bar through ball joints (not shown), and to knuckles (not shown), which are connected to the right and left front wheels, through ball joints (not shown). The configuration from the upper universal joint (not shown) to the right and left front wheels (not shown) is a known configuration.
The steering column SC holds the steering wheel SH in a manner such that the steering wheel is rotatable. The steering column SC includes the steering main shaft 10 that is rotatable integrally with the steering wheel SH; a column tube 20 that houses the steering main shaft 10, and supports the steering main shaft 10 in a manner such that the steering main shaft 10 is rotatable; a lock mechanism 30 that permits or restricts tilt operation of the steering column SC in upward and downward directions and telescopic operation of the steering column SC, in a direction of an axis of the steering column SC (hereinafter, referred to as “column axis direction”); and an electric power steering actuator (hereinafter, referred to as “EPS actuator”) 40 that functions as assist force providing means for providing a predetermined assist force for the operation of the steering wheel SH.
The steering main shaft 10 includes an upper shaft 11, a lower shaft (not shown), and an output shaft 12 connected to the lower shaft (not shown) through a torsion bar (not shown) in a manner such that torque can be transmitted. The upper shaft 11 is hollow. An upper end portion of the upper shaft 11 (i.e., the end portion of the upper shaft 11 close to the driver) is connected to the steering wheel SH. When the steering wheel SH is rotated, the upper shaft 11 is rotated integrally with the steering wheel SH. The lower shaft (not shown) is hollow. A lower end portion of the upper shaft 11 is inserted in the lower shaft in a manner such that the upper shaft 11 is slidable in the column axis direction, and torque can be transmitted.
As shown in
As shown in
Thus, when the lock mechanism 30 is placed in the locked state, the column bracket 23 is fixed (connected) to the breakaway bracket 24 so that the column bracket 23 is immovable. When the lock mechanism 30 is placed in the unlocked state, the column bracket 23 is released from the breakaway bracket 24 so that the column bracket 23 is movable with respect to the breakaway bracket 24. As is generally known, the breakaway bracket 24 is connected to the rear bottom portion of the steering support member SS (i.e., a portion of the vehicle body) in the vehicle so that the breakaway bracket 24 is disconnected from the rear bottom portion of the steering support member SS, and moved toward the front side of the vehicle when a load equal to or above a predetermined value (i.e., a load toward the front side of the vehicle) is applied to the breakaway bracket 24.
As shown in
As shown in
The lock mechanism 30 is a known lock mechanism. The lock mechanism 30 includes a shaft (bolt) 31, a nut (not shown), an operating lever 32, a lock cam unit, and the eccentric cam 33. The shaft (bolt) 31 extends in a lateral direction of the vehicle through a long hole (not shown) for tilt operation, which is formed in the breakaway bracket 24, and the long hole 23a (refer to
When the operating lever 32 is rotated in a counterclockwise direction in
Thus, when the operating lever 32 is rotated in the counterclockwise direction in
The EPS actuator 40 provides assist torque (an assist force) to the output shaft 12 of the steering main shaft 10, to reduce steering torque that is input to the steering wheel SH when the driver rotates the steering wheel SH. As shown in
An output shaft of the electric motor 42 is connected to the output shaft 12 of the steering main shaft 10 through the reducer in a manner such that torque can be transmitted. The electric motor 42 is rotated by controlling supply of electric power to the electric motor 42 according to a torsion amount of a torsion bar (not shown) provided between the lower shaft (not shown) and the output shaft 12 in the steering main shaft 10 (i.e., according to the steering torque detected by a torque sensor (not shown)). Thus, the electric motor 42 provides the assist torque to the output shaft 12 of the steering main shaft 10 according to the steering torque.
In the first embodiment, a screw 51 is provided only in a bottom portion of a fitting portion where a lower-tube support cylindrical portion of the housing 41 of the EPS actuator 40, that is, a rear end portion 41a of the housing 41 in a longitudinal direction of the vehicle is fitted into the lower end portion (the front end portion) of the lower tube 22 in the vehicle, in a manner such that the rear end portion 41a of the housing 41 is integrated with the lower end portion of the lower tube 22. That is, the screw 51 is provided only in the bottom portion of an area where the rear end portion 41 of the housing 41 is integrated with the lower end portion of the lower tube 22. The screw 51 restricts the movement of the rear end portion 41a of the housing 41 and the lower end portion of the lower tube 22 away from each other. Thus, the screw 51 increases connection strength of only the bottom portion of the fitting portion where the rear end portion 41a of the housing 41 is fitted into the lower end portion of the lower tube 22.
In the first embodiment with the above-described configuration, the breakaway bracket 24 is at a set position with respect to the steering support member SS, and the steering column SC is appropriately supported by the steering support member SS, at a normal time (i.e., when a vehicle collision does not occur). Also, in the first embodiment, when the driver collides with the steering wheel SH, and the breakaway bracket 24 receives a load (a secondary collision load) toward the front side of the vehicle, which is equal to or above a predetermined value, at a time of a vehicle collision, the breakaway bracket 24 is disconnected from the steering support member SS, and the breakaway bracket 24 is moved from the set position toward the front side of the vehicle.
At this time (when the breakaway bracket 24 is moved from the set position toward the front side of the vehicle), a bending moment occurs in the fitting portion where the rear end portion 41a of the housing 41 is fitted into the lower end portion of the lower tube 22, due to the secondary collision load. As a result, the rear end portion 41a of the housing 41 pivots downward around the tilt center of the housing 41, and the lower end portion of the lower tube 22 pivots downward so that the lower end portion of the lower tube 22 is disconnected from the rear end portion 41a of the housing 41.
However, in the above-described first embodiment, the screw 51 is provided only in the bottom portion of the area where the rear end portion 41a of the housing 41 is integrated with the lower end portion of the lower tube 22. The portion where the screw 51 is provided (i.e., the bottom portion of the above-described fitting portion) is pulled due to the bending moment, and is more likely to be displaced and deformed than a top portion of the fitting portion (i.e., the portion compressed due to the bending moment), when a secondary collision occurs at a time of a vehicle collision. Accordingly, in the first embodiment, displacement and deformation due to the bending moment are made less likely to occur by the screw 51 provided only in the bottom portion of the fitting portion, and the weight is reduced as compared to the case where the entire fitting portion is reinforced. As a result, it is possible to effectively suppress the displacement and deformation of the lower end portion of the lower tube 22. Thus, the upper tube 21 is appropriately moved in the column axis direction with respect to the lower tube 22.
In the above-described first embodiment, only the bottom portion of the area where the rear end portion 41a of the housing 41 is integrated with the lower end portion of the lower tube 22 (i.e., the bottom portion of the fitting portion) is reinforced by the screw 51. However, only the bottom portion of the area where the rear end portion 41a of the housing 41 is integrated with the lower end portion of the lower tube 22 may be reinforced by a hook 122b in a second embodiment shown in
The hook 122b in the second embodiment shown in
The pin 261a in the third embodiment shown in
In the first embodiment to the third embodiment, the rear end portion of the housing and the lower end portion of the lower tube are constituted by separate members. However, as in a fourth embodiment shown in
In the fourth embodiment, a reinforcement rib 341b, which functions as the reinforcement portion, is integrally formed only in the bottom portion of the area where the rear end portion 341a of the housing 341 is, integrated with the lower end portion of the lower tube 322. The reinforcement rib 341b extends in the column axis direction. A length of the reinforcement rib 341b in the column axis direction is set so that the upper tube 321 is movable a predetermined distance L. Thus, in the forth embodiment, the deformation due to the bending moment is made less likely to occur by the reinforcement rib 341b, and the weight is reduced.
In the fourth embodiment, the reinforcement rib 341b is provided only in the bottom portion of the area where the rear end portion 341a of the housing 341 is integrated with the lower end portion of the lower tube 322. However, a configuration in a fifth embodiment shown in
Also, in the fifth embodiment shown in
While the invention has been described with reference to example embodiments thereof, it is to be understood that the invention is not limited to the described embodiments or constructions. To the contrary, the invention is intended to cover various modifications and equivalent arrangements. In addition, while the various elements of the example embodiments are shown in various combinations and configurations, other combinations and configurations, including more, less or only a single element, are also within the spirit and scope of the invention.
Number | Date | Country | Kind |
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2007-295403 | Nov 2007 | JP | national |
Filing Document | Filing Date | Country | Kind | 371c Date |
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PCT/IB2008/003032 | 11/11/2008 | WO | 00 | 9/28/2009 |