Patent Description:
At Level <NUM> or higher of driving automation at which the system assumes full responsibility in autonomous driving of a vehicle, the driver need not be in charge of operation of the vehicle and therefore need not hold an operating member, such as a steering wheel. A technique of moving an operating member and securing a large space in front of a driver to enhance the driver's comfort during autonomous driving is disclosed, for example, in <CIT>. A steering device having the features of the preamble of claim <NUM> is known from <CIT>. A steering device is known from <CIT> and <CIT> respectively.

A steering device like the aforementioned one that can retract an operating member requires a lock mechanism to lock the movement of the operating member. However, providing a dedicated lock mechanism would complicate the device accordingly.

The present invention provides a steering device that can lock the movement of an operating member without being overly complicated. The present invention is claimed in claim <NUM>. Advantageous embodiments are laid out in the dependent claims.

A steering device according to an aspect of the present invention includes: an operating member that steers a vehicle; a first moving unit that moves in an axial direction of a shaft member having the operating member connected at a rear end, along with the shaft member, and rotatably supports the shaft member; a second moving unit that holds the first moving unit so as to be movable in the axial direction; a holding unit that holds the second moving unit so as to be movable in the axial direction; a first screw mechanism that is disposed between the first moving unit and the second moving unit and moves the first moving unit in the axial direction; a second screw mechanism that is disposed between the second moving unit and the holding unit and moves the second moving unit in the axial direction; a driving unit that outputs driving force for driving the first screw mechanism and the second screw mechanism; and a transmission mechanism that is coupled to the first screw mechanism, the second screw mechanism, and the driving unit and transmits driving force of the driving unit to the first screw mechanism and the second screw mechanism. The steering device moves the operating member between an operation region and a retraction region. One of the first screw mechanism and the second screw mechanism is provided so as to operate in a forward direction when the operating member moves between the retraction region and the operation region, and the reverse efficiency of that one screw mechanism is set such that when the operating member is subjected to an external force directed toward the retraction region, that one screw mechanism does not operate in a reverse direction due to the external force.

A steering device according to an aspect which is not claimed includes: an operating member that steers a vehicle; a first moving unit that moves in an axial direction of a shaft member having the operating member connected at a rear end, along with the shaft member, and rotatably supports the shaft member; a second moving unit that holds the first moving unit so as to be movable in the axial direction; a holding unit that holds the second moving unit so as to be movable in the axial direction; a first screw mechanism that is disposed between the first moving unit and the second moving unit and moves the first moving unit in the axial direction; a second screw mechanism that is disposed between the second moving unit and the holding unit and moves the second moving unit in the axial direction; a first driving unit that outputs driving force for driving the first screw mechanism; and a second driving unit that outputs driving force for driving the second screw mechanism. The steering device moves the operating member between an operation region and a retraction region. Each of the first screw mechanism and the second screw mechanism is provided so as to operate in a forward direction when the operating member moves between the retraction region and the operation region, and the reverse efficiency of each of the first screw mechanism and the second screw mechanism is set such that when the operating member is subjected to an external force directed toward the retraction region, each of the first screw mechanism and the second screw mechanism does not operate in a reverse direction due to the external force.

The present invention can provide a steering device that can lock the movement of an operating member without being overly complicated.

An embodiment of a steering device according to the present invention and a not-claimed modified example will be specifically described below with reference to the drawings. Each of the embodiment and the modified example described below represents a comprehensive or specific example. The numerical values, shapes, materials, constituent elements, positions of arrangement and forms of connection of the constituent elements, steps and the order of the steps, etc. shown in the following embodiment and modified example are examples and not intended to limit the present invention. Those of the constituent elements in the following embodiment and modified example that are not described in the independent claim will be described as optional constituent elements.

The drawings are schematic views in which some parts are exaggerated, omitted, or adjusted in proportion as necessary to show the present invention, and the shapes, positional relationships, and proportions in the drawings may differ from actual ones. Further, when an expression showing a relative direction or a posture, such as "parallel" or "orthogonal," is used in the following embodiment, it also covers a direction or a posture that is not exactly that direction or posture. For example, that two directions are parallel to each other does not only mean that these two directions are perfectly parallel to each other, but also covers a case where these two directions are substantially parallel to each other, i.e., with about a few percent error, for example.

First, an overview of the configuration and the operation of a steering device <NUM> according to the embodiment will be described. <FIG> is a perspective view showing an external appearance of the steering device <NUM> according to the embodiment. <FIG> is a view schematically showing the structure of the steering device <NUM> according to the embodiment. In <FIG>, parts of the steering device <NUM> are schematically shown for clarity, with their positional relationships changed from those in <FIG> and depiction of some members omitted.

The steering device <NUM> according to this embodiment is a device that is, for example, installed in a vehicle, such as an automobile, bus, truck, construction machine, or agricultural machine, that can switch between manual driving and autonomous driving. The steering device <NUM> also has a function of moving an operating member <NUM>, used to steer the vehicle, between an operation region and a retraction region.

Specifically, as shown in <FIG> and <FIG>, the steering device <NUM> includes the operating member <NUM>, a first moving unit <NUM>, a second moving unit <NUM>, a holding unit <NUM>, a first screw mechanism <NUM>, a second screw mechanism <NUM>, a driving unit <NUM>, and a transmission mechanism <NUM>.

The operating member <NUM> is, for example, an annular member called a steering wheel, and is connected at a rear end of a shaft member <NUM>. Specifically, the operating member <NUM> is connected to an operation support part <NUM> through a support member <NUM>. The operation support part <NUM> is a member that rotates as the operating member <NUM> is rotated by a driver's operation, and is a member interposed between the operating member <NUM> and the shaft member <NUM>. Thus, the shaft member <NUM> is connected to the operating member <NUM> through the operation support part <NUM>, and rotation of the operating member <NUM> around a steering axis Aa is transmitted to the shaft member <NUM> through the operation support part <NUM>. Alternatively, the operating member <NUM> may be directly fixed to the shaft member <NUM>.

In <FIG>, an axial direction of the shaft member <NUM> (a direction parallel to the steering axis Aa) corresponds to an X-axis direction, and frontward in the steering device <NUM> is frontward in the vehicle in which the steering device <NUM> is installed and is an X-axis minus direction. Rearward in the steering device <NUM> is a direction opposite from frontward and is an X-axis plus direction. In <FIG>, the steering axis Aa that is a rotational axis of the shaft member <NUM> is indicated by a dashed line. Hereinafter, the term "axial direction" used alone means an axial direction of the shaft member <NUM> (i.e., a direction parallel to the steering axis Aa). In this embodiment, the axial direction and a front-rear direction correspond to each other.

The operating member <NUM> is rotated around the steering axis Aa by the driver's operation, and one or more tires of the vehicle are turned based on the amount of this rotation etc. Specifically, the steering device <NUM> is a device that is incorporated into a so-called steer-by-wire system, and the operating member <NUM> and the tires are not mechanically connected to each other. A turning motor drives one or more tires based on information showing a steering angle of the operating member <NUM> etc. that is output from the steering device <NUM>. While the steering device <NUM> also includes a reaction force device that applies to the operating member <NUM> a torque that opposes a force applied by the driver, depiction and description of this device will be omitted.

In this embodiment, an airbag housing part <NUM> is fixed on the driver's side (an X-axis plus side) of the operation support part <NUM>, and when the operating member <NUM> is seen from the driver's side, the airbag housing part <NUM> is located at a central part of the operating member <NUM>. An airbag (see <FIG>) is housed in the airbag housing part <NUM> in a deployable manner, and an airbag <NUM> deploys by pushing and breaking through the airbag housing part <NUM>, for example, in the event of a collision of the vehicle.

The first moving unit <NUM> is a part that moves in the axial direction along with the shaft member <NUM> and rotatably supports the shaft member <NUM>. Specifically, the first moving unit <NUM> has a box body <NUM> that rotatably supports the shaft member <NUM>. The box body <NUM> houses, for example, a switch for activating a directional indicator.

The second moving unit <NUM> has a guide mechanism <NUM> that slides the box body <NUM> of the first moving unit <NUM>. The guide mechanism <NUM> includes a pair of rails <NUM> and a pair of movable parts <NUM> of which the sliding movement in the axial direction is guided by the rails <NUM>.

The rails <NUM> are rail bodies that are elongated in the axial direction and hold the movable parts <NUM> so as to be slidable in the axial direction. The rails <NUM> are disposed so as to face each other at a predetermined interval in a left-right direction (a Y-axis direction). The movable parts <NUM> are fixed on left and right outer side surfaces of the box body <NUM>. The box body <NUM> and the movable parts <NUM> can slide back and forth in the axial direction by being guided by the rails <NUM>. Thus, the first moving unit <NUM> is held by the second moving unit <NUM> so as to be movable in the axial direction.

The pair of rails <NUM> are coupled together by a coupling member <NUM>. Specifically, the coupling member <NUM> is a metal plate body that is elongated in the left-right direction, and both ends of the coupling member <NUM> are fixed on upper ends of the respective rails <NUM>. Thus, the coupling member <NUM> supports the rails <NUM> while being suspended between the rails <NUM>. Thus integrating the rails <NUM> through the coupling member <NUM> can enhance the rigidity of the rails <NUM> and the coupling member <NUM> as a whole. As a result, backlash can be reduced when the first moving unit <NUM> slides relatively to the second moving unit <NUM> or when the second moving unit <NUM> slides relatively to the holding unit <NUM>.

One of the pair of rails <NUM> (in this embodiment, the rail <NUM> on a Y-axis minus side) is provided with a frame <NUM> that holds the driving unit <NUM> and the transmission mechanism <NUM>. The frame <NUM> is integrated with the rail <NUM> and moves along with the rail <NUM>.

The holding unit <NUM> has a guide mechanism <NUM> that slides the second moving unit <NUM> in the axial direction, and a base member <NUM> that supports the guide mechanism <NUM>.

The guide mechanism <NUM> includes a pair of rails <NUM> and a pair of movable parts <NUM> of which the sliding movement in the axial direction is guided by the rails <NUM>. The rails <NUM> are rail bodies that are elongated in the axial direction and hold the movable parts <NUM> so as to be slidable in the axial direction. The rails <NUM> are disposed so as to face each other at a predetermined interval in the left-right direction. The movable parts <NUM> are fixed on left and right outer side surfaces of the rails <NUM>. The rails <NUM> and the movable parts <NUM> can slide back and forth in the axial direction by being guided by the rails <NUM>. Thus, the second moving unit <NUM> is held by the holding unit <NUM> so as to be movable in the axial direction.

The base member <NUM> couples the pair of rails <NUM> together. Specifically, the base member <NUM> is a substantially box-shaped metal member that is open on a lower side. Upper ends of the respective rails <NUM> are fixed at both ends of the base member <NUM> in the left-right direction. Thus, the base member <NUM> supports the rails <NUM> while being suspended between the rails <NUM>. Thus integrating the rails <NUM> through the base member <NUM> can enhance the rigidity of the rails <NUM> and the base member <NUM> as a whole. As a result, backlash can be reduced when the first moving unit <NUM> slides relatively to the second moving unit <NUM> or when the second moving unit <NUM> slides relatively to the holding unit <NUM>.

The base member <NUM> is provided with a first fixing part <NUM> and a second fixing part <NUM> that are fixed to a vehicle body <NUM>. The first fixing part <NUM> is disposed on a rear side relatively to the second fixing part <NUM>, and couples the base member <NUM> and the vehicle body <NUM> together to fix the base member <NUM> to the vehicle body <NUM>. The second fixing part <NUM> is disposed on a front side relatively to the first fixing part <NUM>, and couples the base member <NUM> and the vehicle body <NUM> together to fix the base member <NUM> to the vehicle body <NUM>.

The structure of the second fixing part <NUM> has lower rigidity than that of the first fixing part <NUM>. Specifically, the first fixing part <NUM> is simply a fastening tool such as a bolt, whereas the second fixing part <NUM> consists of a bent metal plate and a bolt. The base member <NUM> and the vehicle body <NUM> are fixed to each other through the second fixing part <NUM>. Since the bent portion in the metal plate is more fragile than the first fixing part <NUM>, in the event of a collision of the front side of the vehicle, the impact of the collision can be absorbed as this fragile portion deforms. Thus, it can be said that the second fixing part <NUM> has a higher impact-absorbing property than the first fixing part <NUM>. The second fixing part <NUM> may have any structure that has a higher impact-absorbing property than the structure of the first fixing part <NUM>. Specifically, a portion that is shaped so as to be fragile may be formed as described above, or a fragile portion may be formed by, for example, incorporating an elastic material, such as rubber, as part of the second fixing part.

The first screw mechanism <NUM> is disposed between the first moving unit <NUM> and the second moving unit <NUM> and moves the first moving unit <NUM> in the axial direction. Specifically, the first screw mechanism <NUM> has a case body <NUM>, a first nut <NUM>, a sliding screw <NUM>, and a backlash reducing mechanism <NUM>.

<FIG> is a perspective view showing a structure for supporting the first nut <NUM> on the case body <NUM> according to the embodiment. In <FIG>, the outline of the case body <NUM> is indicated by dashed lines.

As shown in <FIG>, the case body <NUM> is a case that houses the sliding screw <NUM> and, in this state, rotatably holds the sliding screw <NUM>. The case body <NUM> extends along the axial direction, and the sliding screw <NUM> is disposed inside the case body <NUM> so as to lie along the axial direction. The first nut <NUM> is also housed inside the case body <NUM>, and the sliding screw <NUM> is screwed in the first nut <NUM>.

The first nut <NUM> is fixed on the box body <NUM> of the first moving unit <NUM> through an impact absorbing member <NUM> to be described later. The movement of the first nut <NUM> in the axial direction is guided by a pair of bushes <NUM>. Specifically, the pair of bushes <NUM> are members that are made of resin and elongated in an X-axis direction. The pair of bushes <NUM> are held on upper edges of the case body <NUM> so as to face each other in the Y-axis direction. The first nut <NUM> is interposed between the pair of bushes <NUM>. The first nut <NUM> is in contact with inner side surfaces of the respective bushes <NUM>. Thus, the posture of the first nut <NUM> is stabilized. The inner side surfaces of the respective bushes <NUM> serve as guide surfaces and guide the movement of the first nut <NUM> in the axial direction.

A plunger <NUM> is provided on a lower surface of the first nut <NUM>. The plunger <NUM> extends in a Z-axis direction, with a ball <NUM> protruding from a lower end surface thereof in a retractable manner. The ball <NUM> is urged by a spring, built inside the plunger <NUM>, in a protruding direction. The ball <NUM> is in contact with an inner bottom surface of the case body <NUM>. Thus, inclination of the first nut <NUM> can be absorbed by the ball <NUM>, and the posture of the first nut <NUM> can be thereby stabilized. Further, when the first nut <NUM> moves in the axial direction, the ball <NUM> guides the movement of the first nut <NUM> by rolling over the inner bottom surface of the case body <NUM>.

The sliding screw <NUM> is disposed along the axial direction inside the case body <NUM>. A front end of the sliding screw <NUM> is connected to the transmission mechanism <NUM>, while the other end thereof is rotatably supported by the case body <NUM>.

The backlash reducing mechanism <NUM> is a part that reduces backlash of the first nut <NUM> relative to the sliding screw <NUM>. <FIG> is a schematic view showing in outline the configuration of the backlash reducing mechanism <NUM> according to the embodiment. As shown in <FIG>, the backlash reducing mechanism <NUM> has an elastic body <NUM>, a fastening part <NUM>, and a washer <NUM>. The elastic body <NUM> is a rubber member that is disposed between the first nut <NUM> and an engaging part <NUM> that is a part of the impact absorbing member <NUM>, and is sandwiched between the first nut <NUM> and the engaging part <NUM>. The engaging part <NUM> and the elastic body <NUM> neither interfere with the sliding screw <NUM> nor hinder the movement of the first nut <NUM> relative to the sliding screw <NUM>. The engaging part <NUM> and the elastic body <NUM> each have, for example, a hole through which the sliding screw <NUM> is passed.

The fastening part <NUM> is a screw body that fastens the engaging part <NUM> and the first nut <NUM> together. The fastening part <NUM> extends through the first nut <NUM> and the elastic body <NUM> and, in this state, is screwed on an internal thread formed in the engaging part <NUM>. The washer <NUM> is a spring washer interposed between the screw head of the fastening part <NUM> and the first nut <NUM>.

<FIG> is a schematic view showing a structure for joining the first nut <NUM> and the engaging part <NUM> together according to a comparative example. As shown in <FIG>, the comparative example is different from the embodiment in that the elastic body <NUM> and the washer <NUM> are not provided. If the elastic body <NUM> and the washer <NUM> are not provided, when the first nut <NUM> and the engaging part <NUM> are fastened together by the fastening part <NUM>, the first nut <NUM> and the engaging part <NUM> may be fixed in a state of being inclined relatively to the sliding screw <NUM> due to backlash between the sliding screw <NUM> and the first nut <NUM>. Specifically, the engaging part <NUM> and the sliding screw <NUM> may be inclined due to backlash of the first moving unit <NUM> on which the engaging part <NUM> is mounted and backlash of the second moving unit <NUM> on which the sliding screw <NUM> is mounted. In this case, when the engaging part <NUM> and the first nut <NUM> are fixed, the first nut <NUM> becomes inclined relatively to the sliding screw <NUM> (see <FIG>). This leads to an increase in torque when the first nut <NUM> and the sliding screw <NUM> move relatively to each other.

In this embodiment, the posture of the first nut <NUM> is stabilized by the pair of bushes <NUM> and the plunger <NUM>, so that backlash of the first nut <NUM> is reduced.

Further, in this embodiment, the aforementioned inclination is absorbed by the elastic body <NUM> and the washer <NUM> as shown in <FIG>, so that creation of backlash and an increase in torque can be avoided. In particular, in this embodiment, since the washer <NUM> is provided, the fastening part <NUM> can be restrained from loosening when permanent deformation of the elastic body <NUM> occurs. The backlash reducing mechanism <NUM> illustrated in this embodiment includes the elastic body <NUM> and the washer <NUM>. However, the backlash reducing mechanism may have any structure that can reduce backlash of the first nut <NUM> relative to the sliding screw <NUM>. For example, a backlash reducing mechanism including either an elastic body or a washer may be adopted.

The second screw mechanism <NUM> is disposed between the second moving unit <NUM> and the holding unit <NUM> and moves the second moving unit <NUM> in the axial direction. Specifically, the second screw mechanism <NUM> includes a second nut <NUM>, a ball screw <NUM>, and an aligning mechanism <NUM>.

The second nut <NUM> is a member that is rotated by the driving unit <NUM> and coupled to the transmission mechanism <NUM>. The ball screw <NUM> is screwed in the second nut <NUM>. A front end of the ball screw <NUM> is rotatably supported and fixed on one rail <NUM> (in this embodiment, the rail <NUM> on the Y-axis minus side) of the holding unit <NUM>. This means that the ball screw <NUM> is fixed so as not to rotate relatively to the holding unit <NUM>. Specifically, a shaft support part <NUM> protruding downward is provided at a front end of the rail <NUM>. The front end of the ball screw <NUM> is coupled to the shaft support part <NUM> through the aligning mechanism <NUM>.

Here, the aligning mechanism <NUM> will be described. The aligning mechanism <NUM> is a mechanism that adjusts the position of the shaft center of the ball screw <NUM> relative to the second nut <NUM>. <FIG> and <FIG> are exploded perspective views showing parts of the aligning mechanism <NUM> according to the embodiment as exploded. Specifically, <FIG> is a perspective view of the parts of the aligning mechanism <NUM> as seen from the rear side, and <FIG> is a perspective view of the parts of the aligning mechanism <NUM> as seen from the front side.

First, the shaft support part <NUM> will be described. The shaft support part <NUM> has a through-hole <NUM> through which the front end of the ball screw <NUM> extends. As shown in <FIG>, a front surface of the shaft support part <NUM> is a plane surface parallel to a YZ-plane. On the other hand, as shown in <FIG>, a rear surface of the shaft support part <NUM> has a pair of recesses <NUM>, <NUM> formed one on each side of the through-hole <NUM> in an up-down direction. The recess <NUM> is disposed on an upper side of the through-hole <NUM> and depressed in a rectangular shape elongated in the Y-axis direction. The recess <NUM> is disposed on a lower side of the through-hole <NUM> and is a notch elongated in the Y-axis direction. A portion between the pair of recesses <NUM>, <NUM> will be referred to as a base portion <NUM>. The base portion <NUM> has a shape elongated in the Y-axis direction, and an upper surface 384a and a lower surface 384b thereof are plane surfaces parallel to an XY-plane. The upper surface 384a and the lower surface 384b contribute to adjusting the position of the shaft center of the ball screw <NUM>. Thus, the shaft support part <NUM> is a part of the aligning mechanism <NUM>.

Next, the aligning mechanism <NUM> will be described in detail. As shown in <FIG> and <FIG>, the aligning mechanism <NUM> includes, in addition to the shaft support part <NUM>, a first aligning member <NUM>, a second aligning member <NUM>, a first washer <NUM>, a second washer <NUM>, and a nut <NUM>.

The first aligning member <NUM> is a substantially ring-shaped member. A protrusion <NUM> elongated in the Z-axis direction is formed on a front surface of the first aligning member <NUM>. A pair of outer side surfaces of the protrusion <NUM> are plane surfaces parallel to an XZ-plane. The protrusion <NUM> extends so as to pass through a central part of the first aligning member <NUM>. A through-hole <NUM> through which the front end of the ball screw <NUM> extends is formed at the central part of the first aligning member <NUM>. The through-hole <NUM> is located inside the protrusion <NUM>. At a predetermined position in the front end of the ball screw <NUM> extending through the through-hole <NUM>, the movement of the first aligning member <NUM> in the axial direction relative to the ball screw <NUM> is restricted.

The second aligning member <NUM> is a substantially ring-shaped member. A first recess <NUM> elongated in the Z-axis direction is formed in a rear surface of the second aligning member <NUM>. The first recess <NUM> extends so as to pass through a central part of the second aligning member <NUM>. A through-hole <NUM> through which the front end of the ball screw <NUM> extends is formed at the central part of the second aligning member <NUM>. The through-hole <NUM> is located inside the first recess <NUM>. A pair of inner side surfaces of the first recess <NUM> are plane surfaces parallel to the XZ-plane. The protrusion <NUM> of the first aligning member <NUM> is fitted in the first recess <NUM>. The pair of outer side surfaces of the protrusion <NUM> are slidable over the pair of inner side surfaces of the first recess <NUM>, and therefore the first aligning member <NUM> and the second aligning member <NUM> are movable in the Z-axis direction relatively to each other while being restricted from rotating relatively to each other. Thus, when the ball screw <NUM> extending through the first aligning member <NUM> and the second aligning member <NUM> moves or inclines in the Z-axis direction, this positional shift is tolerated as the first aligning member <NUM> and the second aligning member <NUM> move relatively to each other.

A second recess <NUM> elongated in the Y-axis direction is formed in a front surface of the second aligning member <NUM>. The through-hole <NUM> is located inside the second recess <NUM>. The second recess <NUM> extends so as to pass through the central part of the second aligning member <NUM>. A pair of inner side surfaces of the second recess <NUM> are plane surfaces parallel to the XY-plane. The base portion <NUM> of the shaft support part <NUM> is fitted in the second recess <NUM>. The pair of outer side surfaces of the base portion <NUM> are slidable over the pair of inner side surfaces of the second recess <NUM>, and therefore the second aligning member <NUM> and the shaft support part <NUM> are movable in the Y-axis direction relatively to each other while being restricted from rotating relatively to each other. Thus, when the ball screw <NUM> extending through the second aligning member <NUM> and the shaft support part <NUM> moves or inclines in the Y-axis direction, this positional shift is tolerated as the second aligning member <NUM> and the shaft support part <NUM> move relatively to each other.

The first washer <NUM> is disposed on an immediately front side of the shaft support part <NUM>, and in this state, the front end of the ball screw <NUM> extends through the first washer <NUM>. A front surface of the first washer <NUM> is a spherical surface that is convex toward the front side. The second washer <NUM> is disposed on an immediately front side of the first washer <NUM>. A rear surface of the second washer <NUM> is a spherical surface that is convex toward the front side. As the front surface of the first washer and the rear surface of the second washer <NUM> slide over each other, a positional shift tolerated by the first aligning member <NUM>, the second aligning member <NUM>, and the shaft support part <NUM> can be absorbed. Thus, during assembly, the position of the shaft center of the ball screw <NUM> relative to the second nut <NUM> can be adjusted.

The nut <NUM> is fastened to an external thread formed at the front end of the ball screw <NUM>. Specifically, the nut <NUM> is fastened to the external thread, and sandwiches other members (the second aligning member <NUM>, the shaft support part <NUM>, the first washer <NUM>, and the second washer <NUM>) between the nut <NUM> and the first aligning member <NUM> to thereby fix to the shaft support part <NUM> the ball screw <NUM> of which the position of the shaft center has been adjusted. Thus, once these parts are assembled, the position and the posture of the ball screw <NUM> are fixed.

As shown in <FIG> and <FIG>, the impact absorbing member <NUM> is disposed so as to be interposed between the first moving unit <NUM> and the first screw mechanism <NUM>, and can thereby absorb the impact of a collision of the driver with the operating member <NUM> (second collision) resulting from a collision between the vehicle and other object.

The impact absorbing member <NUM> is a metal member and has the engaging part <NUM>, a mounting part <NUM>, and a deforming part <NUM>. Specifically, the engaging part <NUM> is a lower end part of the impact absorbing member <NUM>, and is fixed to the first nut <NUM> while the sliding screw <NUM> extends through the engaging part <NUM>. The mounting part <NUM> is an upper end part of the impact absorbing member <NUM>, and is mounted and fixed on the box body <NUM> of the first moving unit <NUM>. The deforming part <NUM> is a part that is provided between the engaging part <NUM> and the mounting part <NUM> and bent into a U-shape, and deforms in a second collision to absorb the impact energy. The deforming part <NUM> is provided, for example, such that the bent part (a bottom part of the U-shape) faces the front side.

As shown in <FIG>, an energy absorption (EA) space <NUM> that is one example of a space for movement that allows the shaft member <NUM> to move frontward is formed inside the box body <NUM> of the first moving unit <NUM>. In a second collision, the shaft member <NUM> moves frontward inside the EA space <NUM> while the impact absorbing member <NUM> deforms under a pressing force from the first moving unit <NUM>. Thus, the impact energy of the second collision is absorbed and the driver's safety is secured. The length of the EA space <NUM> in the axial direction is determined based on, for example, the impact absorbing performance required of the steering device <NUM> and the properties of the impact absorbing member <NUM>.

The technique for absorbing impact by the impact absorbing member <NUM> is not particularly limited. The impact absorbing member <NUM> may absorb impact using, instead of deformation of a single member, a shift (frictional force) between two members that are in contact with each other. Further, a resin member and the impact absorbing member <NUM> may be used in combination to absorb impact energy in two stages, first through breakage of the resin member and then through deformation of the metal impact absorbing member <NUM>, etc. For example, a case is assumed where a resin pin that extends through the U-shaped impact absorbing member <NUM> (see <FIG>) in the up-down direction is disposed on the impact absorbing member <NUM>. In this case, when a second collision occurs, part of the impact energy is absorbed as the resin pin breaks, and subsequently the impact energy is further absorbed as the impact absorbing member <NUM> deforms.

As shown in <FIG> and <FIG>, the driving unit <NUM> is a driving source that synchronously drives the first screw mechanism <NUM> and the second screw mechanism <NUM>. The driving unit <NUM> is held by the frame <NUM>. While the driving unit <NUM> is not particularly limited, in the case of this embodiment, an electric motor is used as the driving unit <NUM>.

The transmission mechanism <NUM> is coupled to the first screw mechanism <NUM>, the second screw mechanism <NUM>, and the driving unit <NUM>, and transmits driving force of the driving unit <NUM> to the first screw mechanism <NUM> and the second screw mechanism <NUM>. Specifically, the transmission mechanism <NUM> is held by the frame <NUM>. The transmission mechanism <NUM> is not particularly limited and may be any mechanism that can transmit driving force of the driving unit <NUM> to the sliding screw <NUM> of the first screw mechanism <NUM> and the second nut <NUM> of the second screw mechanism <NUM>. A belt drive, a combination of gears, etc. can be arbitrarily adopted. In the case of this embodiment, a combination of gears is adopted.

Next, the operation of the parts when moving the operating member <NUM> between the operation region and the retraction region will be described. <FIG> is a view schematically showing the structure of the steering device <NUM> according to the embodiment. Specifically, <FIG> is a view corresponding to <FIG> shows a state where the operating member <NUM> is disposed in the operation region, while <FIG> shows a state where the operating member <NUM> is disposed in the retraction region. Here, the operation region is a region in which the user can operate the operating member <NUM> to drive the vehicle, and which corresponds to the position of the operating member <NUM> when the first moving unit <NUM>, the second moving unit <NUM>, and the holding unit <NUM> have been extended. The retraction region is a region in which the operating member <NUM> is retracted during autonomous driving and the user's operation is not accepted, and which corresponds to the position of the operating member <NUM> when the first moving unit <NUM>, the second moving unit <NUM>, and the holding unit <NUM> have been contracted. For each of the operation region and the retraction region, a certain allowable range in the axial direction is provided.

In this embodiment, the rotation direction of the driving unit <NUM> that is an electric motor, the rotation direction of the sliding screw <NUM>, and the rotation direction of the second nut <NUM> when the operating member <NUM> moves from the operation region to the retraction region will be referred to as a forward rotation direction. On the other hand, the rotation direction of the driving unit <NUM>, the rotation direction of the sliding screw <NUM>, and the rotation direction of the second nut <NUM> when the operating member <NUM> moves from the retraction region to the operation region will be referred to as a reverse rotation direction.

While the rotation directions of each part are termed as the "forward rotation direction" and the "reverse rotation direction" here, there may be a case where the forward rotation direction, for example, of one part is not the same direction as the forward rotation direction of another part. Specifically, the driving unit <NUM>, the sliding screw <NUM>, and the second nut <NUM> are coupled together through the transmission mechanism <NUM>. Depending on the configuration of the transmission mechanism <NUM>, a case may arise where at least one of the sliding screw <NUM> and the second nut <NUM> rotates in a direction reverse to the rotation direction of the driving unit <NUM>. Also in this case, the rotation directions of each part will be referred to as the forward rotation direction. The same applies to the reverse rotation direction.

When the driving unit <NUM> that is an electric motor rotates in the forward direction in the state where the operating member <NUM> is disposed in the operation region as shown in <FIG>, the sliding screw <NUM> of the first screw mechanism <NUM> is rotated in the forward direction through the transmission mechanism <NUM>, and the second nut <NUM> of the second screw mechanism <NUM> is also rotated in the forward direction.

Thus, the first screw mechanism <NUM> operates in the forward direction as the rotational motion of the sliding screw <NUM> is converted into linear motion of the first nut <NUM>. The first nut <NUM> moves in the X-axis minus direction along the sliding screw <NUM>, so that the first moving unit <NUM> also moves in the X-axis minus direction, closer to the second moving unit <NUM>.

Meanwhile, the second screw mechanism <NUM> operates in the forward direction as the rotational motion of the second nut <NUM> is converted into linear motion of the ball screw <NUM>. The ball screw <NUM> moves in the X-axis plus direction relatively to the second nut <NUM>, so that the second moving unit <NUM> moves closer to the holding unit <NUM>.

As a result, the first moving unit <NUM>, the second moving unit <NUM>, and the holding unit <NUM> are contracted and the operating member <NUM> is disposed in the retraction region as shown in <FIG>. When the operating member <NUM> is disposed in the retraction region, the space in front of the driver is expanded, which improves, for example, the driver's comfort.

Next, when the driving unit <NUM> that is an electric motor rotates in the reverse direction in a state where the operating member <NUM> is disposed in the retraction region, the sliding screw <NUM> of the first screw mechanism <NUM> is rotated in the reverse direction through the transmission mechanism <NUM>, and the second nut <NUM> of the second screw mechanism <NUM> is also rotated in the reverse direction.

Thus, the first screw mechanism <NUM> operates in the forward direction as the rotational motion of the sliding screw <NUM> is converted into linear motion of the first nut <NUM>. The first nut <NUM> moves in the X-axis plus direction along the sliding screw <NUM>, so that the first moving unit <NUM> also moves in the X-axis plus direction, farther away from the second moving unit <NUM>.

Meanwhile, the second screw mechanism <NUM> operates in the forward direction as the rotational motion of the second nut <NUM> is converted into linear motion of the ball screw <NUM>. The ball screw <NUM> moves in the X-axis minus direction relatively to the second nut <NUM>, so that the second moving unit <NUM> moves farther away from the holding unit <NUM>.

As a result, the first moving unit <NUM>, the second moving unit <NUM>, and the holding unit <NUM> are extended and the operating member <NUM> is disposed in the operation region as shown in <FIG>. In the operation region, it is also possible to adjust the position of the operating member <NUM> by controlling forward rotation and reverse rotation of the driving unit <NUM>. Specifically, the driver can change the position of the operating member <NUM> in the front-rear direction as he or she intends. Thus, the driver can adjust the position of the operating member <NUM> to a position according to his or her body shape, preference, etc..

As has been described, each of the first screw mechanism <NUM> and the second screw mechanism <NUM> is provided so as to operate in the forward direction when the operating member <NUM> moves between the retraction region and the operation region.

In <FIG>, the respective amounts of movement of the first screw mechanism <NUM> and the second screw mechanism <NUM> are denoted by L1 and L2. The amount of movement L1 of the first screw mechanism <NUM> refers to a relative movable range of the first nut <NUM> relative to the sliding screw <NUM>. The amount of movement L2 of the second screw mechanism <NUM> refers to a relative movable range of the ball screw <NUM> relative to the second nut <NUM>. When the first screw mechanism <NUM> and the second screw mechanism <NUM> are synchronously driven by the driving unit <NUM> such that the operating member <NUM> moves from the operation region to the retraction region (retraction action) or from the retraction region to the operation region (deployment action), the amount of movement L2 of the second screw mechanism <NUM> is larger than the amount of movement L1 of the first screw mechanism <NUM>.

Specifically, the amount of movement L2 is made larger than the amount of movement L1 by, for example, setting the forward efficiency of the second screw mechanism <NUM> higher than the forward efficiency of the first screw mechanism <NUM>. Here, forward efficiency is the ratio of an output to an input when converting rotational motion into linear motion. Specifically, the forward efficiency of the first screw mechanism <NUM> is the ratio of an output to an input when rotating the sliding screw <NUM> to linearly move the first nut <NUM>. The forward efficiency of the second screw mechanism <NUM> is the ratio of an output to an input when rotating the second nut <NUM> to linearly move the ball screw <NUM>. The forward efficiency can be adjusted by adjusting the lead, lead angle, forward friction angle, coefficient of static friction, etc. of each of the first screw mechanism <NUM> and the second screw mechanism <NUM>.

As has been described, the amount of movement L2 of the second screw mechanism <NUM> is larger, and the forward efficiency thereof is higher, than the amount of movement L1 and the forward efficiency of the first screw mechanism <NUM>. Therefore, even when the first screw mechanism <NUM> and the second screw mechanism <NUM> of which the amount of movement L1 is smaller than the amount of movement L2 are synchronously driven by the driving unit <NUM>, the first nut <NUM> and the ball screw <NUM> can be moved at the same timing and their movement can be completed at the same timing.

That the forward efficiency is high can be rephrased as that the speed reduction ratio is low or that the lead is large. Since the first screw mechanism <NUM> and the second screw mechanism <NUM> differ from each other in the efficiency (the speed reduction ratio or the lead), when the first screw mechanism <NUM> and the second screw mechanism <NUM> are synchronously driven, movement of the first screw mechanism <NUM> and movement of the second screw mechanism <NUM> that differ from each other in the amount of movement can be completed at the same timing.

The reverse efficiency of the first screw mechanism <NUM> is set such that when the operating member <NUM> is subjected to an external force F1 directed toward the retraction region, the first screw mechanism <NUM> does not operate in the reverse direction due to the external force F1. Specifically, the external force F1 can be set, for example, as a force that is applied to the operating member <NUM> as a human pushes or pulls the operating member <NUM>. The external force F1 can also be set as a force that is applied to the operating member <NUM> in a second collision. Here, reverse efficiency is the ratio of an output to an input when converting linear motion into rotational motion. Specifically, the reverse efficiency of the first screw mechanism <NUM> is the ratio of an output to an input when linearly moving the first nut <NUM> to rotate the sliding screw <NUM>. The reverse efficiency can be adjusted by adjusting the lead, lead angle, reverse friction angle, reverse friction coefficient, etc. of the first screw mechanism <NUM>.

It is assumed that the external force F1 directed toward the retraction region is applied to the operating member <NUM> as shown in <FIG>. Since the reverse efficiency of the first screw mechanism <NUM> is set such that the first screw mechanism <NUM> does not operate in the reverse direction under the external force F1, the linear motion of the first nut <NUM> relative to the sliding screw <NUM> is restricted. Thus, the movement of the first moving unit <NUM> in the axial direction relative to the second moving unit <NUM> is also restricted.

Meanwhile, the external force F1 also acts on the second moving unit <NUM> through the first moving unit <NUM>. Here, the second screw mechanism <NUM> has high reverse efficiency by employing the ball screw <NUM>. Therefore, the ball screw <NUM> may be moved linearly through the second nut <NUM> due to the external force F1. The second nut <NUM> is coupled to the sliding screw <NUM> of the first screw mechanism <NUM> through the transmission mechanism <NUM>. Since the reverse efficiency of the first screw mechanism <NUM> is set such that the first screw mechanism <NUM> does not operate in the reverse direction as described above, the sliding screw <NUM> is restricted form rotating even under the external force F1. Thus, the transmission mechanism <NUM> coupled to the sliding screw <NUM> that is restricted from rotating is also restricted from moving, so that the second nut <NUM> coupled to the transmission mechanism <NUM> is also restricted from rotating. In the second screw mechanism <NUM>, therefore, the ball screw <NUM> is restricted from moving linearly relatively to the second nut <NUM>.

This restriction is affected by a frictional force between the first nut <NUM> and the sliding screw <NUM>. The frictional force is generated as the tooth flank of the first nut <NUM> is pressed against the tooth flank of the sliding screw <NUM> when a reverse input F2 acts on the first nut <NUM> due to the external force F1. If a force F3 with which the second nut <NUM> tries to rotate becomes larger than this frictional force, the restriction on the second nut <NUM> is removed and the second screw mechanism <NUM> operates in the reverse direction. It is desirable that the gear specifications of the first screw mechanism <NUM> be set such that the second screw mechanism <NUM> does not operate in the reverse direction also in a second collision in which an excessive force F3 can occur.

The steering device <NUM> may further include a tilting mechanism that changes the inclination of the operating member <NUM> in the up-down direction. The tilting mechanism changes the inclination of the operating member <NUM> in the up-down direction by, for example, turning the first moving unit <NUM> around an axis parallel to the left-right direction (the Y-axis direction in <FIG>). Thus, for example, the position of the operating member <NUM> in the up-down direction can be adjusted according to the driver's intention. The tilting mechanism may be configured to change the inclination of the operating member <NUM> in the up-down direction by turning the second moving unit <NUM> around an axis parallel to the left-right direction (the Y-axis direction in <FIG>).

The operation of the driving unit <NUM> having been described above is controlled by a control unit <NUM> (see <FIG>) of the steering device <NUM>. <FIG> is a block diagram showing the functional configuration of the steering device <NUM> according to the embodiment.

The control unit <NUM> acquires various pieces of information and controls the driving unit <NUM> etc. based on the acquired information. For example, the control unit <NUM> acquires a predetermined command given by the driver's predetermined operation or detection results of various sensors. The control unit <NUM> moves the operating member <NUM> in the axial direction by controlling the driving unit <NUM> based on the acquired predetermined command or detection results. The control unit <NUM> acquires, as needed, information showing the positions of the first moving unit <NUM> and the second moving unit <NUM> from the driving unit <NUM>. Thus, the control unit <NUM> can recognize, as needed, the position of the operating member <NUM> that is indirectly supported on the first moving unit <NUM>, relative to a predetermined reference.

The control unit <NUM> performing the above control is realized by, for example, a computer including a central processing unit (CPU), a storage device, such as a memory, an interface for inputting and outputting information, etc. For example, as the CPU executes a predetermined program stored in the storage device, the control unit <NUM> can control the operation of the steering device <NUM> according to control signals sent from a superordinate control unit <NUM> or the like, detection results of sensors, etc..

The airbag <NUM> housed in the airbag housing part <NUM> of the steering device <NUM> is activated according to a command from an airbag control unit <NUM> installed in the vehicle. The airbag control unit <NUM> determines whether to deploy the airbag <NUM> based on, for example, acceleration information received from an acceleration sensor <NUM>. When there is a rapid change in the acceleration rate that is equal to or larger than a threshold value, such as when the vehicle collides with some object, the airbag control unit <NUM> gives a deployment command to the airbag <NUM>, and the airbag <NUM> deploys as the inflator is activated. Thus, the airbag <NUM> inflates instantly.

As described above, the airbag <NUM> basically inflates when a collision between the vehicle and other object occurs. However, if the airbag housing part <NUM> recedes along with the operating member <NUM> to a position far away from the driver, the airbag <NUM> cannot be expected to achieve a sufficient impact absorbing function, due to factors such as the long distance between the airbag <NUM> and the driver and the dashboard being located near the airbag <NUM>. Simply put, the airbag <NUM> fails to fulfil its intended function. Therefore, according to the position of the operating member <NUM>, the airbag housing part <NUM>, or the like acquired from the steering device <NUM>, the superordinate control unit <NUM> performs, for example, control of prohibiting the airbag control unit <NUM> from deploying the airbag <NUM>. In this case, the driver's safety is secured by other airbags etc. (not shown) that are disposed at positions other than on the front side of the driver's seat (e.g., in the ceiling).

In the event of a collision, an excessive force F3 can occur. Even when the reverse efficiency of the first screw mechanism <NUM> is set such that the second screw mechanism <NUM> does not operate in the reverse direction in the event of a collision as described above, it is possible that this setting may not work in all situations. Therefore, when an excessive reverse input into the first screw mechanism <NUM> or the second screw mechanism <NUM> is detected, the control unit <NUM> controls the driving unit <NUM> so as to restrict reverse operation. Specifically, the control unit <NUM> rotates the driving unit <NUM> in a direction reverse to the rotation direction of reverse operation, or stops the rotation of the driving unit <NUM> itself. Thus, reverse operation can be reliably restricted.

To detect an excessive reverse input, a sensor that directly detects the reverse input may be provided. Alternatively, the control unit <NUM> may infer a collision based on acceleration information received from the acceleration sensor <NUM> and thereby detect an excessive reverse input. Further, the control unit <NUM> may detect an excessive reverse input based on a sudden increase in the load on the driving unit <NUM>. Thus, any configuration may be adopted that allows detection of an excessive reverse input into the first screw mechanism <NUM> or the second screw mechanism <NUM>.

As has been described above, in this embodiment, the first screw mechanism <NUM> is provided so as to operate in the forward direction when the operating member <NUM> moves between the retraction region and the operation region, and the reverse efficiency of the first screw mechanism <NUM> is set such that when the operating member <NUM> is subjected to an external force F1 directed toward the retraction region, the first screw mechanism <NUM> does not operate in the reverse direction due to the external force F1. Thus, even when the operating member <NUM> is subjected to the external force F1, the first screw mechanism <NUM> does not convert linear motion attributable to the external force F1 into rotational motion. As a result, the movement of the first moving unit <NUM> is restricted.

The second screw mechanism <NUM> is coupled to the first screw mechanism <NUM> through the transmission mechanism <NUM>. Since the reverse efficiency of the first screw mechanism <NUM> is set such that the first screw mechanism <NUM> does not operate in the reverse direction, the first screw mechanism <NUM> is restricted from rotating under the external force F1. Therefore, the transmission mechanism <NUM> coupled to the first screw mechanism <NUM> that is restricted from rotating is also restricted from moving, so that the second screw mechanism <NUM> coupled to the transmission mechanism <NUM> is also restricted from rotating. Thus, the second screw mechanism <NUM> is also restricted from moving linearly, i.e., the second moving unit <NUM> is restricted from moving. As has been described, simply setting the reverse efficiency of the first screw mechanism <NUM> can restrict the first moving unit <NUM> and the second moving unit <NUM> from moving due to the external force F1. This means that the first screw mechanism <NUM> functions as a lock mechanism. Therefore, without being provided with a dedicated lock mechanism, the steering device <NUM> can restrict the first moving unit <NUM> and the second moving unit <NUM> from moving due to the external force F1. Compared with when a dedicated lock mechanism is provided, the total number of parts can be reduced, the size of the device can be kept down, and the efficiency of installing the device in a vehicle can be increased.

Here, in a not claimed example, the second screw mechanism <NUM> can also function as a lock mechanism. In this case, the reverse efficiency of the second screw mechanism <NUM> is set such that when the operating member <NUM> is subjected to the external force F1, the second screw mechanism <NUM> does not operate in the reverse direction due to the external force F1. However, the second screw mechanism <NUM> is disposed on the front side of the vehicle relatively to the first screw mechanism <NUM>, and is disposed at a position farther away from the side where the external force F1 is input. For this reason, reliably restricting the operation of the first screw mechanism <NUM> may involve complicating the structure of the transmission mechanism <NUM> (increasing the number of gears). This complication is likely to lead to creation of backlash, a decrease in the rigidity, degradation of the lock function, etc. In contrast, making the first screw mechanism <NUM> function as a lock mechanism as described above does not complicate the structure of the transmission mechanism <NUM> and is therefore part of the claimed invention.

Since the amount of movement L2 of the second screw mechanism <NUM> is larger than the amount of movement L1 of the first screw mechanism <NUM>, the amount of movement of the operating member <NUM> can be increased by increasing only the amount of movement L2 of the second screw mechanism <NUM>.

Here, if the amount of movement L1 of the first screw mechanism <NUM> is large, when the parts are extended (when the operating member <NUM> is disposed in the operation region), there is a long distance between the first moving unit <NUM> and the holding unit <NUM>, which causes a decrease in the rigidity of the steering device <NUM> as a whole. Moreover, as the moment applied to the first moving unit <NUM> increases, the influence of the decrease in the rigidity of the steering device <NUM> as a whole is significant. In this embodiment, however, the amount of movement L1 of the first screw mechanism <NUM> is smaller than the amount of movement L2 of the second screw mechanism <NUM>, so that a decrease in the rigidity of the steering device <NUM> as a whole can be avoided.

Since the forward efficiency of the second screw mechanism <NUM> is higher than the forward efficiency of the first screw mechanism <NUM>, even when the first screw mechanism <NUM> and the second screw mechanism <NUM> of which the amount of movement L1 is smaller than the amount of movement L2 are synchronously driven by the driving unit <NUM>, the first nut <NUM> and the ball screw <NUM> can be moved at the same timing as well as their movement can be completed at the same timing.

This makes it possible to avoid a decrease in the rigidity of the device itself while increasing the amount of movement of the operating member <NUM>.

Since the ball screw <NUM> of the second screw mechanism <NUM> that has a larger amount of movement is fixed to the holding unit <NUM> supported on the vehicle body <NUM>, the rigidity of the steering device <NUM> can be further enhanced.

The position of the shaft center of the ball screw <NUM> relative to the second nut <NUM> can be adjusted by the aligning mechanism <NUM>, and therefore the position of the shaft center of the ball screw <NUM> can be adjusted during assembly. The rotational motion of the second nut <NUM> relative to the ball screw <NUM> can be thereby smoothed.

Since the backlash reducing mechanism <NUM> reduces backlash of the first nut <NUM> relative to the sliding screw <NUM>, creation of backlash or an increase in torque between the sliding screw <NUM> and the first nut <NUM> can be avoided. The rotational motion of the sliding screw <NUM> relative to the first nut <NUM> can be thereby smoothed.

Since the second fixing part <NUM> is disposed on the front side relative to the first fixing part <NUM> and has a higher impact-absorbing property than the first fixing part <NUM>, when a collision of the front side of the vehicle occurs, the impact of the collision can be absorbed by the second fixing part <NUM>. The impact can be absorbed as the fragile portion of the second fixing part <NUM> deforms.

The impact absorbing member <NUM> connected to the first moving unit <NUM> absorbs impact as the front end of at least one of the shaft member <NUM> and the first moving unit <NUM> moves in the axial direction toward the front side. Here, the holding unit <NUM> holds not only the second moving unit <NUM> but also the first moving unit <NUM> through the second moving unit <NUM>, and is therefore required to have certain rigidity. In this embodiment, the impact absorbing member <NUM> is connected to the first moving unit <NUM>. Thus, compared with when the impact absorbing member <NUM> is connected to the holding unit <NUM>, a decrease in the rigidity of the holding unit <NUM> can be avoided.

When an excessive reverse input into the first screw mechanism <NUM> or the second screw mechanism <NUM> is detected, the control unit <NUM> controls the driving unit <NUM> so as to restrict reverse operation. Thus, when a situation arises where mechanical limitation alone cannot eliminate the possibility of reverse operation, the control unit <NUM> can control the operation of the driving unit <NUM> so as to reliably restrict reverse operation.

Since the guide mechanism <NUM> guides the movement of the first moving unit <NUM> relative to the second moving unit <NUM>, the first moving unit <NUM> can move smoothly.

The steering device according to the present invention has been described above based on the embodiment. However, the present invention is not limited to the above embodiment. Embodiments incorporating various changes to the above embodiment conceived by those skilled in the art, and embodiments established by combining some of the constituent elements described above, unless departing from the appended claims , are also included in the scope of the present invention.

For example, the external appearance and the configuration of the steering device <NUM> shown in <FIG> are examples, and the shape, size, and position of each constituent element are not limited to the shape, size, and position shown in <FIG>. The configuration of each constituent element need not be the configuration shown in <FIG> etc., either.

In the above embodiment, the case has been illustrated in which the driving unit <NUM> is a single electric motor, and this electric motor is coupled to the first screw mechanism <NUM> and the second screw mechanism <NUM> through the transmission mechanism <NUM>. However, the driving unit may have two electric motors if it can synchronously drive the first screw mechanism <NUM> and the second screw mechanism <NUM>. Specifically, in an aspect which is not claimed, one of the electric motors is coupled to the sliding screw <NUM> of the first screw mechanism <NUM>, while the other electric motor is coupled to the second nut <NUM> of the second screw mechanism <NUM>. In this case, it is also possible to omit the transmission mechanism <NUM>.

When the transmission mechanism <NUM> is omitted, the reverse efficiency of each of the first screw mechanism <NUM> and the second screw mechanism <NUM> may be set such that the screw mechanism does not operate in the reverse direction due to the external force F1. In this aspect, the steering device <NUM> includes: the first moving unit <NUM> that moves in the axial direction of the shaft member <NUM> having the operating member <NUM> connected at the rear end, along with the shaft member <NUM>, and rotatably supports the shaft member <NUM>; the second moving unit <NUM> that holds the first moving unit <NUM> so as to be movable in the axial direction; the holding unit <NUM> that holds the second moving unit <NUM> so as to be movable in the axial direction; the first screw mechanism <NUM> that is disposed between the first moving unit <NUM> and the second moving unit <NUM> and moves the first moving unit <NUM> in the axial direction; the second screw mechanism <NUM> that is disposed between the second moving unit <NUM> and the holding unit <NUM> and moves the second moving unit <NUM> in the axial direction; a first driving unit 160a (see <FIG>) that outputs driving force for driving the first screw mechanism <NUM>; and a second driving unit 160b (see <FIG>) that outputs driving force for driving the second screw mechanism <NUM>.

<FIG> is a block diagram showing the functional configuration of the steering device <NUM> according to a modified example which is not claimed. As shown in <FIG>, the first driving unit 160a and the second driving unit 160b are electrically connected to the control unit <NUM>. The first driving unit 160a is coupled so as to be able to output driving force only to the first screw mechanism <NUM>. The second driving unit 160b is coupled so as to be able to output driving force only to the second screw mechanism <NUM>. The control unit <NUM> acquires various pieces of information and controls the first driving unit 160a and the second driving unit 160b based on the acquired information.

Each of the first screw mechanism <NUM> and the second screw mechanism <NUM> is provided so as to operate in the forward direction when the operating member <NUM> moves between the retraction region and the operation region, and the reverse efficiency of each of the first screw mechanism <NUM> and the second screw mechanism <NUM> is set such that when the operating member <NUM> is subjected to the external force F1 directed toward the retraction region, the screw mechanism does not operate in the reverse direction due to the external force F1. Thus, the steering device <NUM> from which the transmission mechanism is omitted can also fulfil a certain lock function.

In the above embodiment, the case has been illustrated in which the posture of the first nut <NUM> is stabilized by the pair of bushes <NUM> and the plunger <NUM>. However, the steering device may be provided with only either the pair of bushes <NUM> or the plunger <NUM>. Also in this case, the posture of the first nut <NUM> can be stabilized to some degree, and a certain backlash reducing effect can be exerted on the first nut <NUM>.

Claim 1:
A steering device (<NUM>) comprising:
an operating member (<NUM>) that steers a vehicle;
a first moving unit (<NUM>) that moves in an axial direction of a shaft member (<NUM>) having the operating member (<NUM>) connected at a rear end, along with the shaft member (<NUM>), and rotatably supports the shaft member (<NUM>);
a second moving unit (<NUM>) that holds the first moving unit (<NUM>) so as to be movable in the axial direction;
a holding unit (<NUM>) that holds the second moving unit (<NUM>) so as to be movable in the axial direction;
a first screw mechanism (<NUM>) that is disposed between the first moving unit (<NUM>) and the second moving unit (<NUM>) and moves the first moving unit (<NUM>) in the axial direction;
a second screw mechanism (<NUM>) that is disposed between the second moving unit (<NUM>) and the holding unit (<NUM>) and moves the second moving unit (<NUM>) in the axial direction;
a driving unit (<NUM>) that outputs driving force for driving the first screw mechanism (<NUM>) and the second screw mechanism (<NUM>); and
a transmission mechanism (<NUM>) that is coupled to the first screw mechanism (<NUM>), the second screw mechanism (<NUM>), and the driving unit (<NUM>) and transmits driving force of the driving unit (<NUM>) to the first screw mechanism (<NUM>) and the second screw mechanism (<NUM>), wherein:
the steering device (<NUM>) moves the operating member (<NUM>) between an operation region and a retraction region; and
one of the first screw mechanism (<NUM>) and the second screw mechanism (<NUM>) is provided so as to operate in a forward direction when the operating member (<NUM>) moves between the retraction region and the operation region, characterized in that reverse efficiency of that one screw mechanism (<NUM>) is set such that when the operating member (<NUM>) is subjected to an external force directed toward the retraction region, that one screw mechanism (<NUM>) does not operate in a reverse direction due to the external force, wherein when the operating member (<NUM>) is subjected to the external force directed toward the retraction region, that one screw mechanism (<NUM>) functions as a lock mechanism and the other screw mechanism (<NUM>) does not function as a lock mechanism.