JP5402572B2 - Steering device for vehicle - Google Patents

Description

  The present invention relates to a vehicular steering apparatus, and in particular, includes a steering shaft that supports a steering wheel that can be rotated and steered integrally, and a steering mechanism that connects the steering shaft and wheels to steer the wheels. The present invention relates to a vehicle steering apparatus that includes a steering shaft that can be moved to the left and right according to rotation of a steering shaft, and a support member that supports the steering shaft so that the steering shaft can be stroked.

  In this type of vehicle turning device, the turning shaft has connecting members at both ends, and the support member has a restricting portion that can be engaged with each connecting member. The left and right strokes of the steered shaft are regulated by the engagement between the connecting member and the restricting portion, and the maximum left and right stroke amounts of the steered shaft are defined. This type of vehicle steering device is described, for example, in Patent Document 1 below.

  In the vehicle steering device described in Patent Document 1 below, a buffer member (elastic member) capable of coming into contact with a restricting portion (an end surface of the rack housing) is assembled to a connection member (rack end). For this reason, in the vehicle turning device described in Patent Document 1 below, when the left and right strokes of the turning shaft are restricted, it is possible to reduce the impact load acting on the turning shaft by the buffer member. is there.

Japanese Patent Laid-Open No. 2003-31491

  By the way, in the vehicle steering device described in Patent Document 1, for example, the wheel collides with a curb or the like with the hand released from the steering wheel, and the turning shaft moves in the axial direction at a high speed. When the stroke is restricted, a large (rotating) inertia force is transmitted to the steered shaft from the steering system including the steering wheel and the steering shaft. At this time, if a load of a predetermined value or more acts in the axial direction on the steered shaft (connecting member or restricting portion), maintenance / inspection is required for the functional components from the steering shaft to the steered shaft. Such an overload (adverse effect) may have acted (it is assumed that it has acted). In this case, in the vehicle steering device described in Patent Document 1, such a situation (a situation where an overload that requires maintenance / inspection is applied to a functional component from the steering shaft to the steering shaft) is applied. Is not configured to accurately inform the driver.

The present invention has been made in view of the above-described circumstances, and includes a steering shaft that supports a steering wheel that can be turned and rotated together with the steering shaft, and a wheel that connects the steering shaft and the wheel to turn the wheel. A rudder mechanism, the steered mechanism having a connecting member connected to both ends, a steered shaft that can be moved to the left and right according to the rotation of the steering shaft, and a restricting portion that can be engaged with the connecting member And a support member that supports the steered shaft in a strokeable manner, and the left and right strokes of the steered shaft are regulated by engagement of the connecting member and the restricting portion. In the vehicle steering device in which a maximum stroke amount is defined, when a load less than a predetermined value is applied to any one of the connection member and the restriction portion in the axial direction of the steering shaft, the steering is performed. Plastically deformable plastically deformed portion in the axial direction of the steering shaft and load equal to or greater than a predetermined value in the axial direction of the axial direction are plastically undeformable the steering shaft is acted is provided in the plastic The deformed portion is formed by an annular groove portion that is coaxial with the axial center of the steered shaft, is coaxial with the annular groove portion, and can be brought into contact with either the connection member or the restricting portion. It is characterized by being.

  In the vehicle turning device according to the present invention, the left and right strokes of the turning shaft are regulated by the engagement (contact) between the connecting members provided at both ends of the turning shaft and the regulating portions of the support member. By this restriction, the maximum left and right stroke amount of the steered shaft is defined, and the maximum left and right turning steering angle of the steering wheel is defined.

  By the way, when the steered shaft is restricted in the left and right strokes, if a load less than a predetermined value acts in the axial direction of the steered shaft on the plastic deformed portion provided in the connecting member or the restricting portion, the plastic deformed The part does not plastically deform in the axial direction of the steered shaft. Therefore, at this time, the left and right maximum stroke amounts of the steered shaft are maintained at the initial values, and the left and right maximum turning steering angles of the steering wheel are maintained at the initial values. Therefore, the driver turns the steering wheel without feeling uncomfortable thereafter.

  On the other hand, when the left and right strokes of the steered shaft are restricted, for example, the wheel collides with a curb or the like with the hands released from the steering wheel, and the steered shaft moves in the axial direction at a high speed to restrict the stroke. Then, a large (rotating) inertia force is transmitted to the steered shaft from the steering system including the steering wheel and the steering shaft. At this time, when a load of a predetermined value or more is applied to the plastic deformation portion in the axial direction of the steered shaft, the plastic deformation portion is plastically deformed (ruptured after plastic deformation) in the axial direction of the steered shaft.

  Therefore, at this time (when a load of a predetermined value or more is applied to the plastic deformation portion in the axial direction of the steered shaft), the maximum stroke amount of one of the left and right sides of the steered shaft increases from the initial value, and the steering The maximum turning steering angle on either the left or right side of the wheel increases from the initial value. Therefore, by increasing this maximum turning steering angle, it is possible to inform the driver that an overload (adverse effect) that requires maintenance and inspection has been applied to the functional components from the steering shaft to the steered shaft, It is possible to encourage the driver to perform maintenance and inspection at the dealer.

In the present invention , the plastically deformed portion is formed by an annular groove portion that is coaxial with the axial center of the steered shaft, is coaxial with the annular groove portion , and is either the other of the connection member or the restricting portion. Oh Ru at the contact can be the thin annular portion. For this reason , an annular thin portion which is a plastically deformed portion is formed by forming an annular groove portion coaxial with the axial center of the steered shaft in one of the connecting member and the restricting portion. For this reason, it is possible to form the plastically deformed portion easily and inexpensively using the connecting member or the restricting portion, which is an existing component member, and the present invention can be implemented inexpensively and easily.

  In carrying out the present invention, it is also possible to provide an electric motor capable of assisting the rotational driving force on the steering shaft. In this case, when the steered shaft is restricted in the left and right stroke, a large (rotating) inertial force of the electric motor is transmitted from the steering shaft to the plastic deformation portion via the steered shaft. For this reason, at this time, due to the inertial force of the electric motor, a load of a predetermined value or more is likely to act on the plastic deformation portion in the axial direction of the steered shaft, and the effects of the present invention are remarkably obtained.

1 is an overall configuration diagram showing an embodiment of a vehicle steering apparatus according to the present invention. FIG. 2 is a cross-sectional view illustrating a relationship among a rack bar, a rack end, a housing, an end stopper, and a tie rod when the rack bar illustrated in FIG. 1 is in an initial position. FIG. 3 is an enlarged cross-sectional view taken along line 3-3 in FIG. 2. FIG. 3 is an operation explanatory diagram when the rack end (annular thin portion) shown in FIG. 2 abuts against an end stopper. FIG. 5 is an operation explanatory view when the annular thin portion shown in FIG. 4 is plastically deformed (ruptured). It is sectional drawing equivalent to FIG. 2 in deformation | transformation embodiment (When the cyclic | annular thin part is provided in the end stopper).

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings. 1 to 5 show an embodiment of a vehicle steering apparatus according to the present invention. As shown in FIG. 1, this vehicle steering device includes a steering shaft SS that supports a steering wheel SW that can be turned and rotated together with a steering wheel SS, and a predetermined assisting force for turning the steering wheel SW. An EPS (electric power steering) actuator AC, and a steering mechanism SM that connects the steering shaft SS and left and right front wheels (not shown) to steer the left and right front wheels.

  The steering shaft SS includes a steering main shaft 10 that supports the steering wheel SW, an intermediate shaft 20 that is connected to the steering main shaft 10 via an upper universal joint UJ, and a lower universal joint LJ that is connected to the intermediate shaft 20. And the pinion shaft 40 connected to the extension shaft 30 via a connector CM. The steering main shaft 10, the intermediate shaft 20, the extension shaft 30 and the pinion shaft 40 (the steering shaft in the present invention) can rotate integrally.

  As shown in FIG. 1, the EPS actuator AC is a column assist type electric power steering actuator, and includes an electric motor 50 and an EPS computer 51. The electric motor 50 is for assisting the rotational driving force to the steering main shaft 10, and is driven to rotate according to the assist current output from the EPS computer 51. The output shaft of the electric motor 50 is connected to an output shaft (not shown) of the steering main shaft 10 via a speed reducer (not shown). The EPS computer 51 calculates an assist current based on signals output from the motor rotation angle sensor, the steering torque sensor, and the vehicle speed sensor, and outputs the assist current to the electric motor 50.

  As shown in FIG. 1, the steered mechanism SM has a rack bar 60 as a steered shaft that can be moved to the left and right according to the rotation of the steering shaft SS, and a support that supports the rack bar 60 so that the left and right strokes are possible. A housing 70 as a member and a pair of left and right tie rods 80L and 80R connected to both ends of the rack bar 60 via a ball joint BJ (see FIG. 2) are provided. Each tie rod 80L, 80R is connected to the left and right front wheels via a knuckle (not shown).

  The rack bar 60 has a rack (not shown) that meshes with a pinion (not shown) of the pinion shaft 40 on one side of the intermediate portion. For this reason, the rack bar 60 strokes left and right (axial direction) according to the rotation of the pinion shaft 40. The radius of the rack bar 60 (the distance between the outer periphery of the rack bar 60 and the axis center O1) is set to A1 (see FIG. 2). A pair of left and right rack ends 61 as connecting members are connected to both ends of the rack bar 60. Here, since the left rack end 61 and the right rack end 61 are substantially the same, the left rack end 61 will be described as a representative.

  As shown in FIG. 2, the left rack end 61 (hereinafter abbreviated as rack end 61) has a main body portion 61 a formed in a bottomed cylindrical shape (cup shape) and screws on both ends of the rack bar 60. And a threaded portion 61b. A ball joint BJ is constituted by the main body portion 61a of the rack end 61, the spherical head portion 80La of the left tie rod 80L, the ball seat 81, and the like.

  As shown in FIGS. 2 and 3, a circular annular groove portion 61a1 coaxial with the axial center O1 of the rack bar 60 is formed on the bottom portion of the main body portion 61a. The annular groove portion 61a1 is formed by cutting out from the outer peripheral surface of the main body portion 61a in the radially inward direction. The radius of the annular groove portion 61a1 (the distance between the bottom of the annular groove portion 61a1 and the axial center O1) is set to A1. The width of the annular groove portion 61a1 (the length of the groove portion in the axial direction) is set to T1. The width T1 of the annular groove portion 61a1 is a value that is appropriately determined in consideration of the resolution of a steering angle sensor 90 described later. The axial direction is the axial direction of the rack bar 60 and is simply abbreviated as the axial direction in the following description.

  Further, as shown in FIGS. 2 and 3, a circular annular thin portion 61a2 is formed on the bottom portion of the main body 61a by the annular groove portion 61a1. The annular thin portion 61a2 is coaxial with the annular groove portion 61a1 (coaxial with the axial center O1 of the rack bar 60). The annular thin portion 61a2 can abut (engage) with a left end stopper 71 described later. The radius of the annular thin portion 61a2 (the distance between the outer periphery of the annular thin portion 61a2 and the axial center O1) is set to A2. The width of the annular thin portion 61a2 (the thickness of the thin portion in the axial direction) is set to T2.

  The annular thin portion 61a2 cannot be plastically deformed in the axial direction when a load less than a predetermined value is applied in the axial direction, and can be plastically deformed in the axial direction when a load greater than a predetermined value is applied in the axial direction. The annular thin portion 61a2 is a load acting on the weakest portion of the transmission shaft (steering shaft SS, rack bar 60, tie rods 80L, 80R, etc.) connecting the steering wheel SW and the left and right front wheels. On the other hand, it is the part that plastically deforms first (with the smallest load). The annular thin portion 61a2 is a plastically deformed portion in the present invention.

  As shown in FIG. 1, the housing 70 is formed in a cylindrical shape and extends coaxially with the rack bar 60. A pair of left and right end stoppers 71 (regulators) are fixed to the inner periphery of both ends of the housing 70 (see FIG. 2). Since the left end stopper 71 and the right end stopper 71 are substantially the same, the left end stopper 71 will be described as a representative.

  The left end stopper 71 (hereinafter abbreviated as the end stopper 71) is for restricting the right stroke of the rack bar 60, and can contact the rack end 61 (annular thin portion 61a2). . The end stopper 71 is formed in an annular shape, and the rack bar 60 is penetrated therethrough. The inner peripheral radius of the end stopper 71 (the distance between the inner peripheral surface of the end stopper 71 and the axis center O1) is set to A3 and is larger than the radius A1 of the annular groove portion 61a1. For this reason, as shown in FIG. 3, in the annular thin portion 61a2, the outer portion of the diameter than the circle of radius A3 (circle indicated by the phantom line in FIG. 3) abuts on the end stopper 71, and the annular groove portion 61a1. It can be plastically deformed in the axial direction (breaking after plastic deformation) (see FIG. 5).

  In FIG. 2, the steering wheel SW is in the initial position (position where the steering wheel SW is not rotationally steered), and the rack bar 60 is in the initial position (when the left and right front wheels are not steered). The position in position) is shown. The axial distance between the annular thin portion 61a2 of the rack end 61 and the end stopper 71 is set to S1. Therefore, the left and right maximum stroke amounts of the rack bar 60 with respect to the initial position of the steering wheel SW (hereinafter, abbreviated as the maximum stroke amount of the rack bar 60) are set to S1. Note that the left and right maximum turning steering angles (hereinafter, abbreviated as the maximum turning steering angle of the steering wheel SW) with respect to the initial position of the steering wheel SW are set to θ1 (initial value).

  By the way, the steering apparatus for vehicles in this embodiment is provided with the steering angle sensor 90, the electronic controller 91, and the warning device 92, as shown in FIG. The steering angle sensor 90 is for detecting the left and right rotational steering angles with respect to the initial position of the steering wheel SW, and outputs a signal representing the detected rotational steering angle to the electronic control unit 91. The steering angle sensor 90 is provided at the upper end portion of the steering main shaft 10.

  The electronic control unit 91 determines whether the maximum turning steering angle of either the left or right of the steering wheel SW is larger than the initial value θ1 based on the signal indicating the turning steering angle output from the steering angle sensor 90. . Specifically, the electronic control device 91 energizes the alarm device 92 when the maximum turning steering angle of either the left or right of the steering wheel SW is larger than the initial value θ1. On the other hand, the electronic control device 91 does not energize the alarm device 92 when the maximum turning steering angle of either the left or right of the steering wheel SW is equal to or less than the initial value θ1. The alarm device 92 is provided in a combination meter (not shown) in the passenger compartment, and turns on a warning lamp when energized by the electronic control device 91.

  In the first embodiment configured as described above, the left and right strokes of the rack bar 60 are regulated by the contact (engagement) between the left and right rack ends 61 and the left and right end stoppers 71. By this restriction, the maximum left and right stroke amount of the rack bar 60 is defined as the initial value S1, and the maximum left and right turning steering angle of the steering wheel SW is defined as the initial value θ1. The operation and effect when the left rack end 61 and the left end stopper 71 abut, and the operation and effect when the right rack end 61 and the right end stopper 71 abut. Since they are substantially the same, the operation and effect when the left rack end 61 and the left end stopper 71 abut will be described.

  When a load less than a predetermined value is applied to the annular thin portion 61a2 in the axial direction when the rack end 61 (left rack end 61) contacts the end stopper 71 (left end stopper 71). As shown in FIG. 4, the annular thin portion 61a2 is not plastically deformed in the axial direction toward the annular groove portion 61a1. Therefore, at this time, the maximum stroke amount on the right side of the rack bar 60 is maintained at the initial value S1, and the maximum rotation steering angle on the left side of the steering wheel SW is maintained at the initial value θ1. Therefore, the driver turns and steers the steering wheel SW without feeling uncomfortable thereafter. The load acting on the annular thin portion 61a2 includes external force transmitted from the left and right front wheels to the rack end 61 via the tie rods 80L and 80R.

  On the other hand, when the rack end 61 comes into contact with the end stopper 71, for example, the left and right front wheels collide with a curb or the like with the hands released from the steering wheel SW, and the rack bar 60 moves in the axial direction at a high speed to the right. When the stroke is regulated, a large inertial force of the steering wheel SW and a large inertial force of the electric motor 50 are transmitted from the steering system including the steering wheel SW and the steering shaft SS to the rack bar 60 (rack end 61). The At this time, when a load of a predetermined value or more is applied to the annular thin portion 61a2 in the axial direction, the annular thin portion 61a2 (a portion radially outward from the circle of radius A3 shown in FIG. 3) It is plastically deformed in the axial direction toward 61a1 and sheared (broken) into an annular shape.

  Therefore, in this case (when a load greater than a predetermined value is applied to the annular thin portion 61a2 in the axial direction), the rack bar 60 is moved from the state shown in FIG. 4 to the state shown in FIG. A predetermined amount T1 is stroked to the right, the maximum right stroke amount of the rack bar 60 increases from the initial value S1 (increases to S1 + T1), and the maximum left turn steering angle of the steering wheel SW increases from the initial value θ1. Increase by a predetermined amount. Therefore, this increase in the maximum turning steering angle can inform the driver that an overload (adverse effect) that requires maintenance and inspection has been applied to the functional components from the steering shaft SS to the rack bar 60. It is possible to encourage the driver to perform maintenance and inspection at the dealer.

  In this embodiment, a steering angle sensor 90, an electronic control device 91, and an alarm device 92 are provided. For this reason, as described above, when the maximum turning steering angle on the left side of the steering wheel SW increases by a predetermined amount from the initial value θ1, the electronic control device 91 energizes the alarm device 92, and the alarm device 92 turns on the warning lamp. Light. Therefore, at this time, it is possible to accurately notify the driver that an overload that requires maintenance / inspection has been applied to the functional components from the steering shaft SS to the rack bar 60.

  In this embodiment, an annular thin portion 61a2 that is a plastically deformed portion is formed in the rack end 61 by forming an annular groove portion 61a1 that is coaxial with the axial center O1 of the rack bar 60. For this reason, it is possible to form the plastically deformed portion (annular thin portion 61a2) easily and inexpensively by using the rack end which is an existing component member, and the present invention can be implemented inexpensively and easily.

  In the embodiment described above, the plastic deformation portion (annular thin portion) is provided on the rack end 61, but the plastic deformation portion is provided on the end stopper 171 as in the modified embodiment shown in FIG. It is also possible.

  As shown in FIG. 6, the end stopper 171 (regulator) is formed with an annular groove portion 171a coaxial with the axial center O1 of the rack bar 60, and an annular thin portion 171b coaxial with the annular groove portion 171a. Has been. The annular groove portion 171a is formed by cutting out from the inner peripheral surface of the end stopper 171 in the radially outward direction. The radius of the annular groove portion 171a (the distance between the bottom of the annular groove portion 171a and the axis center O1) is set to A4, and the radius of the rack end 61 (between the outer periphery of the rack end 61 and the axis center O1). Distance) Greater than A2. The annular thin portion 171 b can contact the left rack end 61. This annular thin portion 171b is a plastically deformed portion in the present invention. Since the configuration other than the configuration of the above-described modified embodiment is substantially the same as the configuration of the above-described first embodiment, the same reference numerals are given to corresponding portions, and the description thereof is omitted.

  In the above-described modified embodiment, when the rack end 61 and the end stopper 171 (annular thin portion 171b) come into contact with each other, if a load of a predetermined value or more acts on the annular thin portion 171b in the axial direction, The thin portion 171b is plastically deformed in the axial direction toward the annular groove portion 171a and sheared (broken) into an annular shape. Thereby, also in this modified embodiment, the maximum stroke amount on the right side of the rack bar 60 is increased from the initial value S1 (increased to S1 + T1), and substantially the same operational effect as the first embodiment described above is obtained. It is possible.

  In carrying out the above-described embodiment, the fatigue fracture strength of the annular thin portions 61a2 and 171b is appropriately set, and the annular thin portions 61a2 and 171b have a medium load in the axial direction (a load that is not as great as a load of a predetermined value or more). ) Is repeated a predetermined number of times, and the thin annular portions 61a2 and 171b may be configured to be fatigued (broken). In this case, the annular thin-walled portions 61a2 and 171b are subjected to fatigue failure, so that it is possible to inform the driver that a moderate load has repeatedly acted on the functional components from the steering shaft SS to the rack bar 60. It is possible to encourage the necessity of maintenance and inspection at dealers.

  In the above-described embodiment, the steering angle sensor 90, the electronic control device 91, and the alarm device 92 are provided. However, the steering angle sensor 90, the electronic control device 91, and the alarm device 92 may be omitted. It is. In this case, for example, the width T1 of the annular groove portions 61a1 and 171a is increased. Thereby, in this case, when a load of a predetermined value or more acts on the annular thin portion in the axial direction, the increase amount of the maximum turning steering angle of the steering wheel SW is larger than that in the above-described embodiment. Thus, it is possible to easily notify the driver that an overload that requires maintenance / inspection has been applied to the functional components from the steering shaft SS to the rack bar 60.

  In the embodiment described above, the annular groove portions 61a1 and 171a are circular annular groove portions, and the annular thin portions 61a2 and 171b are circular annular thin portions. However, the shapes of the annular groove portion and the annular thin portion can be changed as appropriate. For example, the annular groove portion is a rectangular annular groove portion, and the annular thin portion is a rectangular annular thin portion. It is also possible to implement.

  In the above-described embodiment, the annular thin portions 61a2 and 171b, which are plastically deformed portions, are formed by forming the annular groove portions 61a1 and 171a. However, the configuration of the plastic deformation portion can be changed as appropriate. For example, a flange-like annular thin portion (plastic deformation portion) is integrally provided at the bottom portion of the rack end, or the bottom portion of the rack end. It is also possible to carry out by fixing an annular ring member (plastically deformed portion) to the outer periphery.

  In the above-described embodiment, the EPS actuator AC is a column assist type electric power steering actuator, and the electric motor 50 is configured to assist the steering main shaft 10 with the rotational driving force. However, the EPS actuator is a pinion assist type electric power steering actuator, and the electric motor can be configured to assist the pinion shaft with the rotational driving force, and the EPS actuator can be rack assisted. It is a type of electric power steering actuator, and the electric motor can be configured and implemented to assist the rack bar with rotational driving force.

  In the above-described embodiment, the vehicle steering device is provided with the EPS actuator AC (electric motor 50). However, the vehicle steering device may be provided without the EPS actuator (electric motor). Is possible.

SW ... steering wheel, SS ... steering shaft, AC ... EPS actuator, SM ... steering mechanism, 10 ... steering main shaft, 20 ... intermediate shaft, 30 ... extension shaft, 40 ... pinion shaft, 50 ... electric motor, 51 ... EPS computer, 60 ... rack bar, 61 ... rack end, 61a ... main body, 61a1 ... annular groove part, 61a2 ... annular thin part, 70 ... housing, 71 ... end stopper, 80L, 80R ... tie rod, 171 ... end stopper, 171a ... annular groove portion, 171b ... annular thin portion

Claims (1)

A steering shaft that supports a steering wheel that can be rotated and rotated together, and a steering mechanism that connects the steering shaft and wheels to steer the wheels;
The steering mechanism has a connection member connected to both ends, has a steering shaft that can be moved to the left and right according to the rotation of the steering shaft, and a restricting portion that can be engaged with the connection member. A support member that supports the shaft in a strokeable manner;
In the vehicle steering device in which the left and right strokes of the steered shaft are regulated by the engagement of the connecting member and the restricting portion, and the left and right maximum stroke amounts of the steered shaft are defined.
When a load of less than a predetermined value is applied to any one of the connecting member and the restricting portion in the axial direction of the steered shaft, plastic deformation in the axial direction of the steered shaft is impossible. When a load greater than or equal to a predetermined value is applied in the axial direction, a plastically deformable portion that is plastically deformable in the axial direction of the steered shaft is provided ,
The plastic deformation portion is formed by an annular groove portion that is coaxial with the axial center of the steered shaft, is coaxial with the annular groove portion, and can be brought into contact with either the connection member or the restricting portion. A vehicle steering device characterized by being a thin-walled portion .

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