JP2016124518A - Electric power steering with telescopic function - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electric power steering with a telescopic function, which can improve space-saving property, reduce cost, and adjust a steering position easily.SOLUTION: An electric power steering is a column assist type electric power steering which compensates a driving force for rotating a steering column around its rotation axis by a motor 2. The electric power steering is provided with a telescopic mechanism for adjusting a position of a steering wheel in an axial direction, and a column rotating mechanism 8 for rotating the steering column. The electric power steering is also provided with a switching mechanism 26 for switching between a basic state where the motor 2 is connected to the column rotating mechanism 8 and a position adjustment state where the motor 2 is connected to the telescopic mechanism to adjust the position of the steering wheel in the axial direction.SELECTED DRAWING: Figure 4

Description

  The present invention relates to an electric power steering with a telescopic function provided with a telescopic mechanism in a column assist type electric power steering in which a driving force for rotating a steering column is supplemented by a motor.

As shown in FIG. 6, a telescopic mechanism that adjusts the position of the steering wheel 50 in the axial direction A1 has been put to practical use in order to improve the comfort in the vehicle. This telescopic mechanism is often installed in luxury cars, and is rarely installed in low-priced and compact cars under the current B segment.
In an electric power steering (abbreviated as EPS) installed in a vehicle of B segment or less, a column assist type in which an auxiliary motor for supplementing the rotational driving force of the steering wheel is close to the steering wheel is the mainstream (for example, Patent Document 1, Patent Document 1). 2).

JP-A-6-286620 JP 2008-296752 A

What added a telescopic mechanism to column assist type EPS is not widespread. The reason for this is presumed that the cost is increased and the space-saving property is deteriorated due to the addition of a telescopic mechanism and a motor.
Although there is a tilt and telescopic mechanism that adjusts the steering position by the driver's arm force, it is not suitable for women with many drivers in cars of the B segment and below, and electrification is desirable.

  An object of the present invention is to provide an electric power steering with a telescopic mechanism that can improve space saving and reduce costs, and can easily adjust a steering position.

The electric power steering with a telescopic mechanism of the present invention is a column assist type electric power steering in which a driving force for rotating a steering column about its rotation axis is supplemented by a motor.
A telescopic mechanism is provided to adjust the axial position of the steering wheel.
A column rotation mechanism for rotating the steering column;
A switching mechanism is provided that switches between a basic state in which the motor is connected to the column rotation mechanism and a position adjustment state in which the motor is connected to the telescopic mechanism to adjust and drive the axial position of the steering wheel. And

  According to this configuration, when the driver stops on the driver's seat of the vehicle, the position of the steering wheel in the axial center direction can be adjusted by switching from the basic state to the position adjustment state by the switching mechanism. When adjusting the axial position of the steering wheel, the motor is connected to the telescopic mechanism, so that the telescopic operation can be easily performed with the driving force of the motor regardless of the driver's arm force. Therefore, the steering position according to the driver's physique can be realized, and the steering operation can be suitably performed.

Thereafter, the position adjustment state is switched to the basic state by a switching mechanism. In this basic state, the motor is connected to the column rotating mechanism, so that the driving force for rotating the steering column during driving of the vehicle can be supplemented by the motor. As a result, the steering operation can be performed easily.
In particular, since the switching mechanism is provided and the column assisting motor is also used as the driving motor for the telescopic mechanism, it is possible to improve the space saving and reduce the number of parts and the cost.

  The telescopic mechanism may include a ball screw mechanism that converts a rotational motion of the motor into a linear motion that is a telescopic motion. By using the ball screw mechanism in this way, a quiet and smooth telescopic operation can be performed. In addition, the load and rotation speed required for telescopic operation are small, and a small and inexpensive ball screw mechanism can be selected.

  The ball screw mechanism may include a rotating nut that is rotationally driven by the motor, and a ball screw shaft that expands and contracts a part of the steering column in the axial direction by the rotation of the rotating nut. In the column-assist type electric power steering, since the motor can be installed indoors, it is easy to adopt the ball screw mechanism because the concern that foreign matters are mixed into the motor, the rotating nut, and the ball screw shaft is eliminated.

  The switching mechanism prohibits switching from the basic state to the position adjustment state when the vehicle equipped with the electric power steering is running, and can switch from the basic state to the position adjustment state when the vehicle stops. You may provide the control apparatus which performs control to perform. When the telescopic operation is performed electrically, the drive motor is generally provided separately from the assist motor. In this case, the motor is not used at the same time by performing control that enables switching from the basic state to the position adjustment state only when the vehicle is stopped.

  The electric power steering with a telescopic mechanism according to the present invention is a column assist type electric power steering that supplements a driving force for rotating a steering column around its rotational axis with a motor. A column rotation mechanism for rotating the steering column, a basic state in which the motor is connected to the column rotation mechanism, and an adjustment drive for adjusting the axial direction position of the steering wheel by connecting the motor to the telescopic mechanism A switching mechanism for switching to a position adjustment state is provided. For this reason, space saving and cost reduction can be achieved, and the steering position can be adjusted easily.

1 is a perspective view showing a schematic configuration of an electric power steering according to an embodiment of the present invention. It is a side view of the same electric power steering. It is sectional drawing which shows the support structure etc. of the steering column of the same electric power steering. It is a perspective view which expands and shows the principal part of the same electric power steering. It is a figure which shows the switching mechanism etc. of the electric power steering which concerns on other embodiment of this invention. It is a figure which shows the external appearance of the conventional telescopic mechanism.

An embodiment of the present invention will be described with reference to FIGS.
As shown in FIG. 1, the electric power steering according to this embodiment is a column assist type electric power steering in which a driving force for rotating a steering column 1 around its rotation axis L <b> 1 is supplemented by a motor 2. This electric power steering has a basic configuration including a steering wheel 3, a steering column 1, a rack and pinion mechanism 4, an additional configuration such as other telescopic mechanism 5, and a control device 6. First, the basic configuration will be described.

<About basic configuration>
This electric power steering is basically composed of a steering wheel 3, a steering shaft 7, a steering column 1, a column rotating mechanism 8, an intermediate shaft 9, an input shaft 11 including a pinion shaft 10, a rack and pinion mechanism 4, a rack shaft 12, It has a plurality of bearings (described later), a motor 2, and a torque sensor 13. Among these, the steering shaft 7 and the steering column 1 are provided coaxially with each other in the interior of the vehicle, and are supported to be inclined downward toward the front in the vehicle front-rear direction.
As shown in FIG. 3, for example, the vehicle body is provided with bearings 16 and 17 via a plurality of brackets 14 and 15, respectively, and the steering shaft 7 and the steering column 1 are rotatably supported by these bearings 16 and 17. ing.

  As shown in FIGS. 1 and 2, the steering wheel 3 is fixed to the axial base end portion of the steering shaft 7. A portion of the steering shaft 7 extending from the axial tip to the middle in the axial direction is inserted through the cylindrical steering column 1. The steering column 1 includes an inner cylinder member 18 and an outer cylinder member 19, and the inner cylinder member 18 and the outer cylinder member 19 are coaxially slidable in the axial direction and are slidable relative to the inner cylinder member 18. The outer cylinder member 19 is rotatably fitted.

  As shown in FIG. 3, the steering shaft 7 is fitted to the inner periphery of the inner cylinder member 18 via bearings 20 and 20, and the steering shaft 7 is supported by the inner cylinder member 18 so as to be rotatable around the axis L1. The A retaining ring or the like (not shown) for positioning the bearings 20 and 20 in the axial direction is provided on the outer periphery of the steering shaft 7. By moving the inner cylinder member 18 in the axial direction A1 by a telescopic mechanism 5 (FIG. 1) described later, the steering shaft 7 can move in the axial direction together with the inner cylinder member 18. The bracket 14 that supports the steering shaft 7 is a movable bracket that is movable in the axial direction A1. The outer periphery of the steering shaft 7 in the axial direction front end side (the lower side in FIG. 3) and the inner periphery of the outer cylinder member 19 are spline-fitted or serrated-fitted and can be rotated integrally and in the axial direction A1. It is configured to be movable relative to each other.

  As shown in FIG. 1, an intermediate shaft 9 having joint portions 9 a and 9 a at both ends is connected to an axial end portion of the outer cylinder member 19. An input shaft 11 including a pinion shaft 10 is connected to the joint portion 9 a at the tip of the intermediate shaft 9. A pinion gear 10 a is formed on the outer peripheral surface of the tip end portion in the axial direction of the pinion shaft 10, and a rack gear 12 a is formed on the rack shaft 12. The rack and pinion mechanism 4 is a mechanism that converts the rotational motion of the steering shaft 7 or the like into the linear motion of the rack shaft 12, and includes a rack gear 12a and a pinion gear 10a that meshes with the rack gear 12a.

  As the steering wheel 3 rotates, the steering shaft 7 and the outer cylinder member 19 rotate, so that the pinion shaft 10 of the input shaft 11 rotates via the intermediate shaft 9. The rack and pinion mechanism 4 converts this rotation into a linear motion of the rack shaft 12, that is, a reciprocating motion. Thereby, the turning angle of the wheels 21 and 21 can be changed.

  The column rotating mechanism 8 is a mechanism that rotationally drives the steering column 1, and includes bearings 20 and 20 that support the steering column 1 shown in FIG. 3, and a gear 23 formed on the flange 22 shown in FIG. FIG. 4 is an enlarged view of a portion IV in FIG. A flange 22 is formed on the outer periphery of the input shaft 10, and a gear 23 that can mesh with a pinion gear 24 attached to the motor shaft is formed on the upper surface of the flange 22 that forms an axial plane. In the basic state, the column rotating mechanism 8 is in a state where the gear 23 of the flange 22 is engaged with the pinion gear 24, that is, connected to the motor 2.

As shown in FIG. 1, the torque sensor 13 detects a steering torque and a steering direction input to the steering wheel 3. The torque sensor 13 is provided at an upper portion than the flange 22 of the outer periphery of the input and output shaft 11. The steering force is assisted by transmitting the rotational force of the motor 2 to the input shaft 11 based on the steering torque detected by the torque sensor 13.

<Additional configuration>
This electric power steering has an adjustment switch 25, a telescopic mechanism 5, and a switching mechanism 26 (FIG. 4) as additional components. The telescopic mechanism 5 is a mechanism that adjusts the axial position of the steering wheel 3. The telescopic mechanism 5 includes a ball screw mechanism 27 and a link mechanism 28. The ball screw mechanism 27 is a mechanism that converts the rotational motion of the motor 2 into a linear motion that is a telescopic motion.

  As shown in FIG. 4, the ball screw mechanism 27 moves the rotation nut 27 a rotated by the motor 2 and the inner cylinder member 18 (FIG. 3) of the steering column 1 in the axial direction by the rotation of the rotation nut 27 a. And a ball screw shaft 27b. The rotating nut 27a is rotatably supported by a bearing not shown. A flange 29 is provided on the outer periphery of the rotary nut 27a, and a gear 29a is formed on the lower surface, which is an axial plane of the flange 29. In a state where the gear 29a is engaged with the pinion gear 24 attached to the motor shaft, that is, in a position adjustment state, the rotary nut 27a is rotationally driven.

  As shown in FIGS. 1 and 2, the link mechanism 28 has first and second link members 28 a and 28 b in this example. One end of the first link member 28a in the axial direction is connected to the tip of the ball screw shaft 27b in the swingable manner. A flange 18a is formed on the outer periphery of the inner cylinder member 18, and one end of the second link member 28b in the axial direction is connected to the flange 18a. The other axial ends of the first and second link members 28a and 28b are connected to each other so as to be swingable.

  In the position adjustment state, when the motor 2 is rotated based on the operation amount of the adjustment switch 25 by the driver and the rotation nut 27a is driven to rotate, the ball screw shaft 27b moves in the axial direction. Thereby, the inner cylinder member 18 of the steering column 1 moves in the axial direction via the link mechanism 28. Thus, it is possible to perform a telescopic operation.

  As shown in FIG. 4, the switching mechanism 26 is a mechanism that switches between a basic state and a position adjustment state. For example, the electromagnets 31 that can be attracted to each other provided on the motor main body 2 a and the vehicle body side fixing member 30 31 and a changeover switch 32 (FIG. 1). The motor 2 is configured to be rotatable around a rotation fulcrum 2aa at the base end of the motor body 2a. In the basic state, the electromagnets 31, 31 do not operate separately from each other, and the rotary nut 27a cannot be driven to rotate. When the driver switches the changeover switch 32 (FIG. 1) to the position adjustment state when the vehicle is stopped, the electromagnets 31 and 31 are operated to attract each other (that is, the motor body 2a is rotated around the rotation fulcrum 2aa). The rotation nut 27a is rotationally driven by the motor 2.

<About the control device>
As shown in FIG. 1, the control device 6 is, for example, an electric control unit (ECU) that controls the entire automobile. The control device 6 includes a basic control unit 6a and a switching control unit 6b. The basic control unit 6a performs a predetermined current control on the motor 2 based on the steering torque, the steering direction, and the vehicle speed signal detected by the torque sensor 13. The steering direction is determined by the sign of the torque value.

  The vehicle speed signal is obtained from, for example, a speed sensor provided in the vehicle. For example, when the vehicle speed is lower than the high speed range, the control device 6 assists the steering force so that the current applied to the motor 2 is increased and the steering operation becomes lighter. The relationship between the vehicle speed, the steering torque, and the motor current is stored in a relationship setting unit including a map, for example. These relationships are determined by the results of, for example, tests and simulations.

  The switching control unit 6b prohibits the switching mechanism 26 (FIG. 4) from switching from the basic state to the position adjustment state by the changeover switch 32 when the vehicle travels, and can switch from the basic state to the position adjustment state when the vehicle stops. Control is performed. The switching control unit 6b determines, for example, whether the vehicle is running or stopped based on a vehicle speed signal from the speed sensor.

  Further, the switching control unit 6b performs a predetermined current control on the motor 2 based on the adjustment amount given from the adjustment switch 25 in the position adjustment state. After that, the switching control unit 6b switches to the basic state when it detects engine start, an operation amount of an accelerator pedal (not shown), or a vehicle speed signal from the speed sensor. Note that the relationship between the adjustment amount and the motor current is determined by the results of, for example, tests and simulations.

  According to the electric power steering described above, when the driver gets in the driver's seat of this vehicle, the switching mechanism 26 switches from the basic state to the position adjustment state, and operates the adjustment switch 25, so that the shaft of the steering wheel 3 can be operated. The cardiac position can be adjusted. When the position of the steering wheel 3 in the axial direction is adjusted, the motor 2 is connected to the telescopic mechanism 5 so that the telescopic operation can be easily performed with the driving force of the motor 2 regardless of the arm strength of the driver. Therefore, the steering position according to the driver's physique can be realized, and the steering operation can be suitably performed.

Thereafter, when the vehicle is run, the switching mechanism 26 switches the position adjustment state to the basic state. In this basic state, the motor 2 is connected to the column rotating mechanism 8, so that the driving force for rotating the steering column 1 during driving of the vehicle can be supplemented by the motor 2. As a result, the steering operation can be performed easily.
In particular, since the switching mechanism 26 is provided and the column assist motor 2 is also used as the driving motor 2 for the telescopic mechanism 5, it is possible to improve the space saving and reduce the number of parts and the cost. .

  Since the telescopic mechanism 5 includes the ball screw mechanism 27 that converts the rotational motion of the motor 2 into a linear motion, a quiet and smooth telescopic operation can be performed. The load and rotation speed necessary for the telescopic operation are small, and a small and inexpensive object can be selected as the ball screw mechanism 27. In the column-assist type electric power steering, the motor 2 can be installed indoors, so that the concern of foreign matter entering the motor 2, the rotating nut 27a, and the ball screw shaft 27b is eliminated. easy. When the telescopic operation is performed electrically, the drive motor is generally provided separately from the assist motor. In this embodiment, the motor 2 is not used at the same time by performing control that enables switching from the basic state to the position adjustment state only when the vehicle is stopped.

Another embodiment will be described.
In the following description, the same reference numerals are given to the portions corresponding to the matters described in the preceding forms in each embodiment, and the overlapping description is omitted. When only a part of the configuration is described, the other parts of the configuration are the same as those described in advance unless otherwise specified. The same effect is obtained from the same configuration. Not only the combination of the parts specifically described in each embodiment, but also the embodiments can be partially combined as long as the combination does not hinder.

In the embodiment shown in FIG. 4, the motor main body 2a is rotated around the rotation fulcrum 2aa to switch between the basic state and the position adjustment state. However, the embodiment is not limited to this example.
For example, as shown in FIG. 5, the motor 2 may be moved along this axial direction to switch between the basic state and the position adjustment state. In this case, gears 23 and 29a are formed not on the axial plane of the flanges 22 and 29 but on the outer peripheral surface. The motor shaft is provided with two stages of pinion gears 24a and 24b along the axial direction.

As shown in FIG. 5A, when the vehicle is operated, the electromagnets 31, 31 are attracted to each other to engage the pinion gear 24a on the base end side and the gear 23 of the flange 22 on the input shaft 11 side. Therefore, the driving force for rotationally driving the steering column can be supplemented by the motor 2.
As shown in FIG. 5B, when the vehicle is stopped, the electromagnets 31 are separated from each other to engage the pinion gear 24b on the tip side and the gear 29a of the flange 29 on the ball screw mechanism side. Therefore, the telescopic operation can be easily performed by the driving force of the motor 2.

  If the motor is provided near the steering wheel, the link mechanism may be omitted. In this case, the number of parts can be reduced, the structure can be simplified, and the cost can be further reduced.

  As mentioned above, although the form for implementing this invention based on embodiment was demonstrated, embodiment disclosed this time is an illustration and restrictive at no points. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

DESCRIPTION OF SYMBOLS 1 ... Steering column 2 ... Motor 3 ... Steering wheel 5 ... Telescopic mechanism 6 ... Control apparatus 8 ... Column rotating mechanism 26 ... Switching mechanism 27 ... Ball screw mechanism 27a ... Rotating nut 27b ... Ball screw shaft

Claims (4)

In column-assisted electric power steering that supplements the driving force that rotates the steering column around its rotational axis with a motor,
A telescopic mechanism is provided to adjust the axial position of the steering wheel.
A column rotation mechanism for rotating the steering column;
A switching mechanism is provided that switches between a basic state in which the motor is connected to the column rotation mechanism and a position adjustment state in which the motor is connected to the telescopic mechanism to adjust and drive the axial position of the steering wheel. Electric power steering with telescopic mechanism.   The electric power steering with a telescopic mechanism according to claim 1, wherein the telescopic mechanism has a ball screw mechanism that converts a rotational motion of the motor into a linear motion that is a telescopic motion.   3. The electric power steering with a telescopic mechanism according to claim 2, wherein the ball screw mechanism includes a rotating nut that is rotationally driven by the motor and a part of the steering column that extends and contracts in the axial direction by the rotation of the rotating nut. Electric power steering with a telescopic mechanism having a ball screw shaft.   The electric power steering with a telescopic mechanism according to any one of claims 1 to 3, wherein the switching mechanism is changed from the basic state to the position adjustment state when a vehicle on which the electric power steering is mounted travels. An electric power steering with a telescopic mechanism provided with a control device that prohibits switching and performs control to switch from the basic state to the position adjustment state when the vehicle stops.

Images