JP4899305B2 - Vehicle steering system - Google Patents

Description

  The present invention belongs to the technical field of a vehicle steering apparatus in which an operation unit and a steering unit are connected via a cable column.

As this type of vehicle steering device, the steering torque input to the steering wheel is transmitted to the steering gear box via the cable column, and the operation of the electric power steering device is controlled based on the steering torque. The device is known. The electric power steering device prevents the deterioration of the durability of the cable by outputting a steering assist force so that the load torque of the cable is less than the durability limit (see, for example, Patent Document 1).
JP-A-10-310069

  However, the conventional technology has a configuration in which the steering assist force is output in consideration of the durability limit of the cable, and thus there is a problem that the steering torque becomes too light and the steering feeling is deteriorated.

  The present invention has been made paying attention to the above problems, and an object of the present invention is to provide a vehicle steering apparatus capable of ensuring both the durability of the cable and the improvement of the steering feeling.

In order to achieve the above object, in the present invention, an operation unit having an operation input means and a steered unit that steers a steered wheel are directly or indirectly connected via a cable column, and the operation unit Steering torque detection means for detecting a steering torque input to the steering unit, a steering actuator for outputting a steering assist force to the steering unit, and a steering actuator for controlling the steering actuator according to the steering torque input to the operation unit. In a vehicle steering apparatus comprising: a rudder control means; a vehicle speed detection means for detecting a vehicle speed; and a reaction force actuator that outputs a steering reaction force to the operation unit.
Steering torque detection means for detecting the steering torque input to the steering unit;
Reaction force control means for controlling a reaction force actuator only in accordance with the vehicle speed and the steering torque;
Provided ,
The cable column is
A steering side cable pulley provided in the operation section;
A steered wheel side cable pulley provided in the steered portion;
Two inner cables that are connected to both cable pulleys while being wound in opposite directions;
A first pulley case for accommodating the steering side cable pulley;
A second pulley case for housing the steering wheel side cable pulley;
Two outer tubes covering both inner cables and connecting both pulley cases;
Have
An elastic member that covers the inner cable is provided between at least one end of the two outer tubes and the pulley case .

  In the vehicle steering apparatus according to the present invention, the steering assist force is output by the steering actuator in consideration of the cable durability limit, while the reaction force actuator applies the steering reaction force to the operation unit, and the steering feeling is light. It can be prevented from becoming too much. Therefore, both durability of the cable and improvement in steering feeling can be achieved.

  DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments for realizing a vehicle steering device of the present invention will be described based on Examples 1 to 5 shown in the drawings.

  Example 1 is an example in which the operation unit and the turning unit are directly connected via a cable column.

First, the configuration will be described.
FIG. 1 is an overall system diagram illustrating a vehicle steering apparatus according to a first embodiment.
As shown in FIG. 1, the vehicle steering apparatus according to the first embodiment includes an operation unit 2, a steered wheel 3, a steered unit 4, a steering torque sensor (steering torque detection means) 5, a reaction force actuator 6, and a column shaft 7. , Steering actuator 8, steering torque sensor (steering torque detection means) 9, pinion shaft 10, steering mechanism 11, cable-type column 12, vehicle speed sensor 13, controller (steering control means and reaction force control means) 14, It has.

  The operation unit 2 is provided with a steering wheel (operation input means) 1 and a column shaft 7. The column shaft 7 is provided with a reaction force torque sensor 5 and a reaction force actuator 6. A cable type column 12 is provided between the column shaft 7 and the pinion shaft 10.

  The steered portion 4 is provided with a pinion shaft 10. A rack and pinion type steering mechanism 11 is connected to a lower end portion of the pinion shaft 10, and a rack gear shaft is moved on both sides of the steering mechanism 11. Steering wheels 3 and 3 that can change the turning angle are provided.

  The pinion shaft 10 is provided with a turning actuator 8 and a turning torque sensor 9. The steered actuator 8 uses a DC motor, but other motors such as an AC motor may be used.

  As the motors of the reaction force actuator 6 and the steering actuator 8, a brushless DC motor is used. This type of motor is generally a steering angle sensor (steering angle detection means) 15 such as an encoder and a steering angle sensor 16. To control the motor drive.

  The cable-type column 12 is provided between the operation unit 2 and the steered unit 4 and transmits the steering torque from the steering wheel 1 and the reaction force torque from the steered wheels 3 and 3.

  The controller 14 inputs sensor signals from the reaction force torque sensor 5, the turning torque sensor 9, the vehicle speed sensor 13, and the like, controls the reaction force actuator 6 provided in the operation unit 2, and is provided in the turning unit 4. The steered actuator 8 is controlled.

  FIG. 2 is a control block diagram of the controller 14. The controller 14 includes a reaction force actuator command value calculation unit 14a, a cable pulley torque calculation unit 14b, and a turning actuator command value calculation unit 14c.

  The reaction force actuator command value calculation unit 14a is based on the “steering torque sensor detected value—reaction force actuator command torque characteristic” shown in FIG. 8 based on the sensor signals of the vehicle speed sensor 13 and the steering torque sensor 9. Calculate the command value. The reaction force actuator command value is output to the current servo 17.

  The cable pulley torque calculation unit 14 b calculates the cable pulley torque based on the current value output from the current servo 17 to the reaction force actuator 6 and the sensor signal of the reaction force torque sensor 5. The cable pulley torque is output to the steered actuator command value calculation unit 14c.

  The steered actuator command value calculation unit 14c calculates a steered actuator command value from the sensor signal of the reaction force torque sensor 5 based on “steering side cable pulley torque-steering actuator command torque characteristics” shown in FIG. . The steered actuator command value is output to the current servo 18, and the current servo 18 outputs a drive current to the steered actuator 8 in accordance with the steered actuator command value.

Next, the detailed structure of the cable column 12 will be described.
3 is a transverse sectional view and a longitudinal sectional view showing the cable type column 12, FIG. 4 is a perspective view showing the cable type column 12, and FIG. 5 is a sectional view of the inner cable.

  The cable type column 12 includes a steering side cable pulley 20a provided at the end of the column shaft 7, a steered wheel side cable pulley 20b provided at the end of the pinion shaft 10, and both cable pulleys 20a and 20b. The two cables 20c and 20g and the cables 20d and 20h are connected to each other while being wound in opposite directions.

  The steering side cable pulley 20a provided at the end of the column shaft 7 is housed in the first pulley case 20e, and the ends of the two cables 20c and 20g and the cables 20d and 20h are fixed to the outer periphery of the pulley. In addition, a cable groove is formed that guides one of the two cables 20c and 20g and the cables 20d and 20h, and guides the other cable to rewind.

  The steered wheel side cable pulley 20b provided at the end of the pinion shaft 10 is housed in the second pulley case 20f, and the ends of the two cables 20c and 20g and the cables 20d and 20h are provided on the outer periphery of the pulley. In addition to being fixed, a cable groove is formed which guides one of the two cables 20c and 20g and the cables 20d and 20h, and guides the other cable to rewind.

  The two cables 20c and 20g and the cables 20d and 20h include two inner cables 20c and 20d wound around the cable grooves of the steering side cable pulley 20a and the steering wheel side cable pulley 20b, and the first pulley case 20e. It comprises two flexible outer tubes 20g and 20h that connect the second pulley case 20f.

  As shown in FIG. 4, the outer tubes 20g and 20h have a large number of metal wires 201g and 201h arranged in the axial direction along the outer periphery of the liners 200g and 200h made of a synthetic resin pipe material having a low frictional resistance. Metal strips 202g, 202h are spirally wound around and the outer periphery is covered with synthetic resin coatings 203g, 203h. And inner cables 20c and 20d made of metal strands such as stainless steel and aluminum as shown in FIG. 5 are slidably accommodated in the outer tubes 20g and 20h. Therefore, the outer tubes 20g and 20h support the tensile force acting in the axial direction by a large number of metal wires 201g and 201h to prevent the occurrence of elongation deformation, and the metal wires when the inner cables 20c and 20d are bent. It is possible to bend the outer tubes 20g and 20h by suppressing the separation of 201g and 201h with the metal strips 202g and 202h and winding the metal strips 202g and 202h in a spiral shape.

  That is, the cable-type column 12 has two cable pulleys 20a and 20b provided at the end of the column shaft 7 and the end of the pinion shaft 10 wound around the cable pulleys 20a and 20b in opposite directions. When the steering wheel 1 is rotated in one direction, one of the two cables 20c, 20g and the cables 20d, 20h is connected to the driver. By transmitting the steering torque input from the steering wheel and the other cable transmitting the reaction force torque input from the steered wheels 3 and 3, the same function as that of the column shaft is exhibited.

Next, the operation will be described.
[Steering actuator command value calculation control process]
FIG. 6 is a flowchart illustrating the flow of the steering actuator command value calculation control process executed by the controller 14 of the first embodiment. Hereinafter, each step will be described. This control flow is executed, for example, every predetermined period after the ignition key switch is turned on.

  In step S101, the detected value of the reaction force torque sensor 5 is read in the cable pulley torque calculator 14b, and the process proceeds to step S102.

  In step S102, the cable pulley torque calculator 14b reads the reaction force actuator current value of the current servo 17 and proceeds to step S103.

  In step S103, the cable pulley torque calculation unit 14b calculates the output torque of the reaction force actuator 6 by multiplying the reaction force actuator current value by a predetermined torque coefficient, and proceeds to step S104.

  In step S104, the cable pulley torque calculation unit 14b calculates the steering side cable pulley torque by subtracting the reaction force actuator torque from the detected value of the reaction force torque sensor 5, and proceeds to step S105.

  In step S105, the steering actuator command value calculation unit 14c calculates the steering actuator command value based on the “steering side cable pulley torque−steering actuator command torque characteristics” shown in FIG. Is calculated, and this control is terminated.

  Here, the “steering side cable pulley torque-steering actuator command torque characteristics” shown in FIG. 7 can be arbitrarily set from the target cable tension by the following two methods.

  (i) When the steering-side cable pulley torque is the no-load sliding torque of the steering-side cable pulley 20a, the steering-side cable pulley torque and the steering actuator command torque are set so that the output torque of the steering actuator 8 is maximized. Set characteristics.

  (ii) When the steering-side cable pulley torque is the product of the inner cable tension and the cable pulley radius that are the durability limit of the outer tubes 20g and 20h, or the inner cable 20c and 20d is the durability limit. When the cable tension is multiplied by the cable pulley radius, the characteristics of the steering side cable pulley torque and the steering actuator command torque are set so that the steering actuator output torque becomes maximum.

[Ensuring cable durability]
In the cable-type column 12, when a tensile force acts on the inner cables 20c and 20d, a compressive force acts on the outer tubes 20g and 20h, and conversely, when a compressive force acts on the inner cables 20c and 20d, the outer tubes 20g and 20h A tensile force acts. When the cable is used in a bent state, a tensile force acts on the outer tube 20g (20h) on the outer side in the bending direction and a compressive force acts on the outer tube 20h (20g) on the inner side in the bending direction. Become.

  Therefore, when these two types of tensile forces are applied simultaneously or when two types of compressive forces are applied simultaneously, the metal wires 201g and 201h may be greatly deformed without being able to withstand the load. If the metal wires 201g and 201h are greatly deformed in this way, the outer tubes 20g and 20h may be suddenly bent at the portions, and smooth sliding of the inner cables 20c and 20d may be hindered. The inner cables 20c and 20d are twisted lines of metal wires, and when subjected to repeated loads in the axial direction, the inner cables 20c and 20d are expanded and contracted to cause abrasion of the metal wires.

  The durability of the cable varies depending on the cable arrangement and the cable tension. Generally, the cable curvature of the arrangement is large, and the smaller the cable tension, the higher the durability. For reference, the SN diagram characteristics of the inner cable have the characteristics shown in FIG. 9 as in the case of the paper (No. 65-02 20025222). This SN diagram characteristic changes according to the specifications of the inner cables 20c and 20d.

  In general, the difference between the output torque and the input torque of the cable column 12 increases as the arrangement bending angle and the input torque increase. Since the conventional shaft column is supported by the bearing, the difference between the output torque and the input torque is mainly the friction of the bearing portion and does not change with the input torque.

In the cable type column 12, the difference between the input torque and the output torque can be approximately calculated using the following formula (1).
F = We ^μθ (1)
Here, F is the input torque, W is the output torque, μ is the outer tube liner friction coefficient, θ is the planned bending angle, and the natural logarithm base e = 2.718.

Therefore, the difference FW between the input torque and the output torque is expressed by the following equation (2).
F−W = W (e ^μθ −1) (2)

  In addition, since the cable has flexibility, when it is mounted on a vehicle, the variation in the routing angle of the cable is large, so that the difference between the output torque and the input torque is also large.

  As the load torque applied to the cable column 12 increases, the difference between the input torque and the output torque also increases, and the sliding resistance increases. Therefore, as shown in FIGS. 10 and 11, since the output torque is smaller than the input torque, the steering feeling is felt awkward and the steering feeling is deteriorated.

[Contrast with conventional technology]
In order to solve this problem, in the technique described in Japanese Patent Laid-Open No. 10-310069, in a combination of a cable column and a power steering device, an assist force that cancels the friction of the cable is generated in the power steering device, The steering feeling is improved.

  In this prior art, a steering torque input to the steering wheel is detected by a torque sensor provided between the steering and the cable, and the operation of the power steering motor that drives the steering gear box is controlled based on the steering torque. . Since the steering torque detected by the torque sensor includes cable friction, a steering torque that cancels the cable friction is generated in the power steering motor, and an appropriate steering feeling is obtained.

  However, with respect to input changes from the steering wheel side, such as a change in cornering force generated by the steering wheel during traveling, the torque change is not sufficiently transmitted to the steering wheel due to friction of the cable portion. In such a case, for example, while traveling on a low μ road such as a snowy road, the change in the road surface is not sufficiently transmitted to the steering.

  In addition, when driving at high speed, it is necessary to give an appropriate weight to the steering, but the steering torque detected by the torque sensor is almost equal to the load torque of the cable column. Therefore, if an appropriate steering torque is applied during high-speed traveling, the load torque applied to the cable column increases as described above (= appropriate steering torque is applied during high-speed traveling). Increased, the steering feeling feels awkward, and the steering feel deteriorates.

  This becomes conspicuous when the steering is turned back from the turning state. Since the input torque acting direction from the steering wheel is different from the friction acting direction of the cable column, these torque components cannot be determined by the torque sensor.

  On the other hand, in Example 1, in order to reduce the tension applied to the inner cables 20c and 20d, adjustment can be performed by generating a steering assist force by the turning actuator 8. As this trade-off, the steering torque may be reduced, and the drivability may be deteriorated. As a countermeasure, a reaction force actuator 6 is installed between the steering wheel 1 and the cable column 12. The reaction force actuator 6 generates an appropriate steering reaction force to improve drivability.

  Since the turning torque sensor 9 is provided between the cable column and the steered wheels 3 and 3, the input change from the steered wheels 3 and 3 can be detected without being affected by the cable friction. Based on the detected torque value, torque is generated by the reaction force actuator 6 and transmitted to the driver to improve the steering feeling (FIG. 8).

Next, the effect will be described.
In the vehicle steering apparatus according to the first embodiment, the following effects can be obtained.

  (1) The steering actuator 8 outputs the steering assist force in consideration of the cable durability limit, and the reaction force actuator 6 applies the steering reaction force to the steering wheel 1 to ensure the durability of the cable and the steering feeling. It can balance improvement.

  (2) Since the reaction force actuator 6 generates a steering reaction force based on the sensor signal of the turning torque sensor 9, the road surface feel can be given to the driver accurately, and the steering feeling is improved. In addition, it is possible to correct the steering torque from becoming too light by the steering assist force of the steering actuator 8.

  (3) Steering-side cable pulley torque-steering actuator command torque characteristics are set such that when the steering-side cable pulley torque is the no-load sliding torque of the steering-side cable pulley 20a, the output torque of the steering actuator 8 is maximized. Therefore, the change in the sliding resistance of the cable-type column 12 can be suppressed, and a uniform astringency can be obtained regardless of the change in the steering torque, and the change in the feeling of strangeness in the steering feeling can be reduced.

  (4) When the steering-side cable pulley torque-steering actuator command torque characteristic is obtained by multiplying the steering-side cable pulley torque by the inner cable tension that is the endurance limit of the outer tubes 20g and 20h and the cable pulley radius. Alternatively, when the inner cable tension, which is the durability limit of the inner cables 20c, 20d, is multiplied by the cable pulley radius, the inner actuator 20c, 20d is set so as to maximize the steering actuator output torque. It is possible to reduce the rubbing wear that occurs between the metal winding lines, and the durability is improved. Further, the sliding resistance between the inner cables 20c, 20d and the outer tubes 20g, 20h can be reduced, and the durability is improved.

  (5) Since the turning torque sensor 9 is provided between the turning actuator 8 and the steered wheels 3 and 3, the road surface feel can be accurately transmitted to the driver, and the steering feeling is improved. In addition, it is possible to correct the steering torque from becoming too light by the steering assist force of the steering actuator 8.

  The vehicle steering apparatus according to the second embodiment is an example in which a steering actuator command value is calculated using sensor signals of the steering angle sensor 15 and the steering angle sensor 16 instead of the steering torque sensor.

  First, the configuration will be described. In addition, the same code | symbol is attached | subjected to the component same as Example 1, and the overlapping description is abbreviate | omitted.

  FIG. 12 is an overall system diagram illustrating the vehicle steering apparatus according to the second embodiment. The vehicle steering apparatus according to the second embodiment is different from the first embodiment in that the reaction force torque sensor 5 illustrated in FIG. 1 is omitted. .

  FIG. 13 is a control block diagram of the controller 14 according to the second embodiment. The turning actuator command value calculation unit 30 calculates “angle deviation−” shown in FIG. 14 from the sensor signals of the steering angle sensor 15 and the turning angle sensor 16. A steering actuator command value is calculated based on the “turning actuator command torque characteristics”. The width W in FIG. 14 can be arbitrarily set by the two methods shown in the first embodiment.

Next, the effect will be described.
In the vehicle steering apparatus of the second embodiment, the following effects can be obtained in addition to the effects (1) to (5) of the first embodiment.

  (6) The steering actuator 8 is provided with a steering torque sensor for detecting the steering torque of the driver in the operation unit 2 in order to generate a steering assist force based on the sensor signals of the steering angle sensor 15 and the steering angle sensor 16. Therefore, the cable tension can be reduced. Furthermore, the apparatus can be made compact and the cost can be reduced.

  Example 3 is an example in which the operation unit and the steered unit are indirectly connected via a cable column.

First, the configuration will be described. In addition, the same code | symbol is attached | subjected to the component same as Example 1, and the overlapping description is abbreviate | omitted.
FIG. 15 is an overall system diagram illustrating the vehicle steering apparatus according to the third embodiment. The third embodiment is an example of a steer-by-wire (SBW) system that uses the cable-type column 12 as a fail safe.

  The operation unit 2 includes a steering wheel 1, a reaction force actuator 41 including a steering torque sensor and a steering angle sensor, a first column shaft 7a, a clutch unit 43, and a second column shaft 7b in order from the upper end. A cable column 12 is provided between the second column shaft 7b and the pinion shaft 10 as a cable type backup mechanism.

  The steered portion 4 is provided with a pinion shaft 10. A rack and pinion type steering mechanism 11 is connected to a lower end portion of the pinion shaft 10, and a rack gear shaft is moved on both sides of the steering mechanism 11. Steering wheels 3 and 3 that can change the turning angle are provided.

  The pinion shaft 10 is provided with a turning actuator 42 having a turning torque sensor. In addition, although the DC brushless motor is used as a motor of the steering actuator 42 and the reaction force actuator 41, a motor with a DC brush may be used. As the steering angle sensor and the turning angle sensor, a resolver type angle sensor is used, but an encoder type angle sensor or the like may be used. This angle sensor is also used for driving control of the DC brushless motor.

  The SBW controller 44 inputs sensor signals from the steering angle sensor 15, the turning angle sensor 16, the vehicle speed sensor 13, etc., and controls the reaction force actuator 41 and the clutch portion 43 provided in the operation unit 2, and also turns the steering. The steering actuator 42 provided in the unit 4 is controlled.

  For example, when the power of the SWB system is turned on, the clutch control unit of the SBW controller 44 outputs a command to release the connected clutch unit 43 when the power is turned off, and then determines that the SWB system is normal. The release of the clutch unit 43 is maintained as long as possible, and when it is determined that a failure has occurred in the SBW system, a command to connect the released clutch unit 43 is output.

Next, the detailed structure of the clutch part 43 is demonstrated.
FIG. 16 is a longitudinal sectional view of the clutch portion 43.
A rotor 51 having a flange 51 a is provided around the first column shaft 7 a via a boss 50. The rotor 51 is provided on the same axis as the second column shaft 7b. An armature hub 52 having a flange 52a is spline fitted to the second column shaft 7b. An armature 53 is provided outside the flange 52a of the armature hub 52 in the radial direction. The armature 53 is fixed to the flange 52a via a leaf spring 54, and is disposed to face the suction surface 510a of the flange 51a.

  Around the rotor 51, a yoke 55 fixed to a column housing (or a fixing housing) (not shown) is provided. The yoke 55 has a built-in electromagnetic coil 55a. The leaf spring 54 is formed integrally with the armature 53 via an annular base 54a fixed to the side surface of the flange 52a opposite to the yoke 55, and bridges 54b extending radially to the base 54a. This is formed by an annular body including an annular free end portion 54c fixed to a side surface opposite to the yoke 55.

  In the clutch portion 43 configured as described above, when the electromagnetic coil 55a is energized, a magnetic flux Φ is generated. At this time, since the armature 53 is attracted to the flange 51a of the rotor 51 against the restoring force of the leaf spring 54, the first column shaft 7a and the second column shaft 7b are connected. When the column rotates, this rotational force is transmitted to the steering wheel 1 via the clutch. When the energization of the electromagnetic coil 55 a is released, the magnetic flux Φ disappears and the armature 53 is separated from the rotor 51 by the restoring force of the leaf spring 54.

  Here, the transmission torque capacity of the clutch portion 43 can be arbitrarily set because the attractive force changes by changing the magnetic flux that can be generated by the electromagnetic coil 55a.

Next, the operation will be described.
[Turning actuator command value calculation control process during backup]
FIG. 17 is a flowchart illustrating the flow of the steering actuator command value calculation control process during backup executed by the SBW controller 44 according to the third embodiment. Hereinafter, each step will be described. This control flow is executed, for example, every predetermined period after the ignition key switch is turned on.

  In step S201, it is determined whether a failure has occurred in the SBW system. If YES, the process proceeds to step S202, and if NO, this control is terminated.

  In step S202, the failure occurrence part is disconnected and the clutch part 43 is connected at the same time, and the process proceeds to step S203.

  In step S203, the detected values of the steering torque sensor, the reaction force torque sensor, and the vehicle speed sensor 13 are read, and the process proceeds to step S204.

  In step S204, the steering actuator command value calculation unit 14c calculates the steering actuator command based on the “steering side cable pulley torque−steering actuator command torque characteristics” shown in FIG. The value is calculated, and the process proceeds to step S203.

Next, the effect will be described.
In the vehicle steering apparatus of the third embodiment, the effects (1) to (5) of the first embodiment can be obtained when the SBW system has a failure in the SBW system including the cable type backup mechanism.

  Example 4 is an example in which, in the SBW system of Example 3, a cable tension adjusting spring (corresponding to a telescopic member) is provided between the ends of the two outer tubes of the cable-type column and the pulley case. .

First, the configuration will be described.
18A is a plan view, FIG. 18B is a side view, FIG. 19B is a rear view, and FIG. 19 is a diagram of the inner cables 20c and 20d to both cable pulleys 20a and 20b. It is a figure which shows a winding state.

  As shown in FIG. 18, a cable tension adjusting spring 20j is provided between the ends of the two outer tubes 20g and 20h and the first pulley case 20e. In the fourth embodiment, a coil spring is used as the cable tension adjusting spring 20j. As shown in FIG. 20, the inner diameter of this coil spring is set sufficiently larger than the inner diameter of the outer tube 20g (20h).

  Further, a cable tension adjusting nut 20k is provided between the second pulley case 20f and the ends of the two outer tubes 20g and 20h. The cable tension adjusting nut 20k adjusts the tension by moving the outer tube 20g (20h) in the axial direction by changing the position of the nut.

Next, the operation will be described.
[Deterioration of steering feeling due to cable friction difference]
FIG. 21 is a (a) perspective view, (b) side view, and (c) plan view showing an example of cable routing to a vehicle. As shown in FIG. (Radius, total bending angle, etc.) do not match completely.

  In the cable-type column, the cable friction changes depending on the contact state between the outer tube and the inner cable due to the cable bending state. Therefore, when the two cable bending states are different, a friction difference is generated in the rotation direction of the pulley.

  Therefore, when the cable column is used as a fail safe for the SBW system, when the SBW is operating normally (when the cable is rotated), the clutch unit is provided on the steering unit side and the cable is rotated around the steering wheel. A difference in steering force occurs in each direction. Further, when the clutch is provided on the operation unit side and the cable is rotated around the steering rack, stick-slip occurs in the movement of the rack in the turning to the higher friction, and the smoothness of the left and right turning is different. Further, when the SBW is abnormal (when turning by a cable) and in the cable-type column, a difference in friction occurs when the steering wheel rotates left and right, and a difference in steering feeling occurs when the wheel rotates left and right.

[Cable tension adjustment]
On the other hand, in Example 4, when there is a difference in the friction between the two cables depending on the cable routing state, the spring constant (corresponding to the expansion / contraction ratio) of the cable tension adjustment spring 20j of the cable in which the friction increases in advance. ) Is set larger, an effect equivalent to that of making the outer tube longer can be obtained.

  At this time, the cable tension adjusting spring 20j is a coil spring and has a smaller contact area with the inner cable 20c (20d) than the outer tube 20g (20h), so that the cable friction can be reduced.

  Further, since the inner diameter of the cable tension adjusting spring 20j is sufficiently larger than the inner diameter of the outer tube 20g (20h), the inner cable 20c (20d) is wound around the upper and lower end portions of the cable pulley 20a, particularly when it is stationary. When the rewinding guidance is performed, the cable friction can be further reduced because it is less likely to contact the inner cable 20c (20d) than in the case of the outer tube 20g (20h).

  Further, the greater the cable friction is, the more the cable constant adjustment spring 20j is set to have a larger spring constant, and the friction is further reduced, whereby the durability of the cable can be improved.

  In the present embodiment, an example in which a coil spring is applied as the elastic member has been described. However, an elastic body such as rubber, or a structure in which the pulley case and the outer tube slide, the outer tube according to the tension of the outer tube. What is necessary is just a structure which can be expanded-contracted between the edge part of this and the edge part of a pulley case.

Next, the effect will be described.
In the vehicle steering apparatus according to the fourth embodiment, the following effects can be obtained.

  (7) The cable type column 12 is opposite to the steering side cable pulley 20a provided in the operation unit 2, the steered wheel side cable pulley 20b provided in the steered unit 4, and the cable pulleys 20a and 20b. Two inner cables 20c and 20d that are coupled in a state of being wound in a direction, a first pulley case 20e that houses a steering side cable pulley 20a, and a second pulley case 20f that houses a steered wheel side cable pulley 20b Two outer tubes 20g and 20h that respectively cover the inner cables 20c and 20d and connect the pulley cases 20e and 20f, and at least one end of the two outer tubes 20g and 20h 1 Cable tension adjusting cover that covers the inner cables 20c and 20d between the pulley case 20e Since the pulling 20j is provided, the friction difference between the two cables can be reduced even when the two cable bending states are different, and the influence of the friction difference on the steering feeling is eliminated when the cable is rotated and steered by the cable. be able to.

  (8) The cable tension adjusting spring 20j sets the spring constant with the larger total bending angle of the cable to be larger than the spring constant with the smaller total bending angle, so that the two cables are bent in different directions. Even when the friction is different, by adjusting the spring constant of the cable tension adjusting spring 20j, the difference in friction can be reduced, and the left and right steering feeling at the time of the cable rotation and the turning by the cable can be matched.

  (9) Since the cable tension adjusting spring 20j sets a larger spring constant as the cable friction is larger, the cable friction is smaller and the durability of the cable can be improved.

FIG. 22 is a cross-sectional view illustrating a configuration of a cable column according to the fifth embodiment.
In the cable type column of the fifth embodiment, the inner cable 20c (20d) is applied to the steering wheel side cable pulley 20a of the first pulley case 20e by applying the elastic force of the cable tension adjusting spring 20j to the SBW system of the fourth embodiment. In this example, the outer tube 20g (20h) is set so as not to be displaced toward the first pulley case 20e when being wound.

  More specifically, the elastic force of the cable tension adjusting spring 20j is between the inner cable 20c (20d) and the outer tube 20g (20h) in a state where the inner cable 20c (20d) is at its maximum extension due to aging or the like. The maximum frictional sliding resistance that is set to be equal to or greater than the maximum frictional sliding resistance generated and that is generated between the inner cable 20c (20d) and the outer tube 20g (20h) in the initial state when the vehicle is mounted. It is set to be more than force.

As shown in FIG. 23, the cable adjusting spring 20j is a tip in the initial state of the vehicle when is in the initial position A ₀ in FIG, when the inner cable 20c (20d) is maximized for growth, the tip is located the a _1.

  Further, the elastic force of the cable tension adjusting spring 20j is set so that the bending amount of the outer tube 20g (20h) becomes a predetermined value or less when the inner cable 20c (20d) reaches the maximum elongation due to aging or the like. Yes. For example, the predetermined value is set by a bending radius or the like in which the frictional sliding resistance generated between the inner cable 20c (20d) and the outer tube 20g (20h) is within an allowable range.

Next, the operation will be described.
[Outer tube return suppression action]
As shown in FIG. 23, when the inner cable 20c (20d) is stretched and loosened due to aging or the like, the tension of the inner cable 20c (20d) is reduced, and the outer tube 20g (20h) is connected to the cable tension adjusting spring 20j. The spring force pushes it away from the pulley shaft (left direction in FIG. 22).

  When the inner cable 20c (20d) is taken up when the steering side cable pulley 20a is taken up in this state, the outer tube 20g (20h) is moved by the spring force of the cable tension adjusting spring 20j and the outer tube 20g ( 20h) and the inner cable 20c (20d) return to the pulley shaft side of the steering cable pulley 20a to a position where the frictional sliding resistance acting between them is balanced.

  Thereafter, the steering wheel side cable pulley 20b (FIG. 4) opposite to the rotated steering side cable pulley 20a starts to rotate. Therefore, when the spring force of the cable tension adjusting spring 20j is smaller than the frictional sliding resistance force between the outer tube 20g (20h) and the inner cable 20c (20d), this loss becomes steering backlash.

  On the other hand, in the fifth embodiment, when winding the steering side cable pulley 20a, the cable tension adjustment is performed so that the outer tube 20g (20h) generates a spring force that is greater than or equal to the maximum force for returning to the pulley axial direction. Since the preset load of the spring 20j is always applied to the cable tension adjusting spring 20j from the initial position to the position where the inner cable 20c (20d) reaches the maximum extension, the above loss can be eliminated and the occurrence of steering play is generated. Can be suppressed.

  Here, a force to keep away from the pulley shaft of the steering side cable pulley 20a is always applied to the outer tube 20g (20h) by the cable tension adjusting spring 20j, so that the inner cable 20c (20d) is extended. The accompanying slack does not occur.

Next, the effect will be described.
In the vehicle steering system according to the fifth embodiment, the following effects can be obtained.

  (10) When the inner cable 20c (20d) is wound around the steering side cable pulley 20a of the first pulley case 20e in contact with the cable tension adjustment spring 20j, the elastic force of the cable tension adjustment spring 20j is Since the tube 20g (20h) is set to a size that does not displace toward the first pulley case 20e, the return of the outer tube 20g (20h) during steering can be prevented, and steering backlash can be suppressed.

  (11) The elastic force of the cable tension adjusting spring 20j is the maximum frictional sliding resistance generated between the inner cable 20c (20d) and the outer tube 20g (20h) when the inner cable 20c (20d) is fully extended. Since the force is set to be equal to or greater than the force, it is possible to suppress the occurrence of steering play when the elongation of the inner cable inner cable 20c (20d) is maximized due to aging degradation or the like.

  (12) The elastic force of the cable tension adjusting spring 20j is not less than the maximum frictional sliding resistance force generated between the inner cable 20c (20d) and the outer tube 20g (20h) in the initial state when the vehicle is mounted. Therefore, the occurrence of steering backlash can always be suppressed from the initial state when the vehicle is mounted to the case where the elongation of the inner cable 20c (20d) is maximized due to deterioration over time.

  (13) The elastic force of the cable tension adjusting spring 20j is set so that the bending amount of the outer tube 20g (20h) is not more than a predetermined value in the maximum extension state of the inner cable 20c (20d). Even when 20c (20d) bends, the frictional sliding resistance generated between the inner cable 20c (20d) and the outer tube 20g (20h) can be within an allowable range, and cable friction can be suppressed. .

  24 is a cross-sectional view showing the configuration of the cable-type column of the sixth embodiment, FIG. 25 is a cross-sectional view of S25-S25 of FIG. 24, and the cable-type column of the sixth embodiment This is an example in which contraction displacement restricting means 21 for restricting displacement in the contraction direction of the tension adjusting spring 20j is provided.

  An outer tube mounting guide 22 that supports the outer tube 20g (20h) is provided at an edge of the outer tube 20g (20h). A cable tension adjusting spring 20j is interposed between the outer tube mounting guide 22 and the first cable case 20e.

  A first cable case insertion portion 22a is provided on the first cable case 20e side of the outer tube mounting guide 22, and an outer tube 20g is provided around the first cable case insertion portion 22a from the first cable case 20e side. A plurality of groove portions 21a having a substantially triangular cross section inclined toward the (20h) side are provided in the axial direction.

  The first cable case 20e is provided with a stopper portion 21b having an inner peripheral shape into which the first cable case insertion portion 22a can be inserted by a flexible material and engaging with the groove portion 21a. Due to the engagement between the stopper portion 21b and the groove portion 21a, the first cable case insertion portion 22a moves in the direction of jumping out from the first pulley case 20e, but cannot move in the direction of entering the first cable case 22e. Yes. The groove portion 21a and the stopper portion 21b constitute a shrinkage displacement regulating means 21 that permits displacement in the extension direction (left direction in FIG. 24) of the cable tension adjusting spring 20j and restricts displacement in the shrinkage direction. Here, the contraction displacement restricting means 21 is not limited to this configuration, and may be any one that allows displacement in the extension direction and restricts displacement in the contraction direction.

Next, the operation will be described.
[Outer tube return suppression action]
When the inner cable 20c (20d) is loosened due to aging or the like, the outer tube 20g (20h) is separated from the pulley axial direction, the outer tube mounting guide 22 jumps out of the first pulley case 20e, and the outer tube 20g (20h) is in this position. Therefore, the inner cable 20c (20d) is in a tensioned state with no slack.

  If the steering wheel side cable pulley 20a is taken up in this state, the frictional sliding resistance between the outer tube 20g (20h) and the inner cable 20c (20d) when the inner cable 20c (20d) is taken up. A force is generated, which acts as a force for pushing the outer tube 20c (20d) back to the pulley shaft side of the first cable case 20e.

  On the other hand, in Example 6, the outer tube 20g (by the engagement of the groove portion 21a provided in the first cable case insertion portion 22a of the outer tube mounting guide 22 and the stopper portion 22 provided in the first cable case 20e. 20h) is restricted from moving toward the first cable case 20e. As a result, the displacement of the cable tension adjusting spring 20j in the contraction direction can be prevented, and the occurrence of steering backlash is suppressed.

Next, the effect will be described.
In the vehicle steering device of the sixth embodiment, the following effects can be obtained.

  (14) Since the cable tension adjusting spring 20j is allowed to be displaced in the extending direction and is provided with the contraction displacement restricting means 21 for restricting the displacement in the contraction direction, the outer tube 20g (20h) can be prevented from returning during steering, and the steering backlash can be prevented. Can be suppressed.

  The vehicle steering apparatus according to the seventh embodiment is an example in which a steered actuator command value is calculated based on the rotation angles of both cable pulleys.

  First, the configuration will be described. In addition, the same code | symbol is attached | subjected to the component same as Example 2, and the overlapping description is abbreviate | omitted.

FIG. 26 is an overall system diagram illustrating the vehicle steering apparatus according to the seventh embodiment. The vehicle steering apparatus according to the seventh embodiment replaces the steering angle sensor 15 and the steering angle sensor 16 illustrated in FIG. The second embodiment is different from the second embodiment in that a steering side angle sensor 19a for detecting the rotation angle of the cable pulley 20a and a steering wheel side angle sensor 19b for detecting the rotation angle of the steering wheel side cable pulley 20b are provided. Sensor signals of the steering side angle sensor 19a and the steered wheel side angle sensor 19b are input to the controller 14.

  FIG. 27 is a control block diagram of the controller 14 of the seventh embodiment. The steered actuator command value calculation unit 30 includes a sensor signal (corresponding to a steering angle) of the steering side angle sensor 19a and a steering wheel side angle sensor 19b. From the sensor signal (corresponding to the turning angle), the steering actuator command value is calculated based on the “steering side cable pulley torque-steering actuator command torque characteristic” shown in FIG.

Next, the effect will be described.
In the vehicle steering apparatus of the seventh embodiment, in addition to the effects (1) to (5) of the first embodiment, the following effects can be obtained.

  (15) The steered actuator 8 is based on a steering-side angle sensor 19a that detects the rotation angle of the steering-side cable pulley 20a, and a steering-wheel-side angle sensor 19b that detects the rotation angle of the steering-wheel-side cable pulley 20b. Thus, since the steering assist force is generated, the cable tension can be reduced without providing the operation unit 2 with a steering torque sensor for detecting the steering torque of the driver. In addition, the device can be made compact.

(Other examples)
As mentioned above, although the vehicle steering device of the present invention has been described based on the first to fifth embodiments, the specific configuration is not limited to the first to fifth embodiments, and each claim of the claims Design changes and additions are allowed without departing from the gist of the invention.

  For example, although the electromagnetic clutch is used as the clutch unit in the third embodiment, a friction clutch may be used.

1 is an overall system diagram illustrating a vehicle steering apparatus according to a first embodiment. 2 is a control block diagram of a controller 14. FIG. It is the cross-sectional view and longitudinal cross-sectional view which show the cable type column 12. FIG. 4 is a perspective view showing the cable type column 12. FIG. 5 is a cross-sectional view of the inner cable. 3 is a flowchart showing a flow of a steering actuator command value calculation control process executed by a controller 14 of the first embodiment. It is a steering side cable pulley torque-steering actuator command torque characteristic view. It is a turning torque sensor detection value-reaction force actuator command torque characteristic figure. It is a figure which shows the SN diagram characteristic of an inner cable. It is an output torque characteristic figure with respect to input torque when the load torque concerning a cable type column is large. It is a characteristic view of the difference of input torque and output torque with respect to input torque when load torque concerning a cable type column is large. It is a whole system figure which shows the steering apparatus for vehicles of Example 2. FIG. FIG. 6 is a control block diagram of a controller 14 according to a second embodiment. It is an angle deviation-steering actuator command torque characteristic view. FIG. 6 is an overall system diagram illustrating a vehicle steering apparatus according to a third embodiment. 4 is a longitudinal sectional view of a clutch portion 43. FIG. It is a flowchart which shows the flow of the steering actuator command value calculation control process at the time of the backup performed by the SBW controller 44 of Example 3. It is (a) top view, (b) side view, and (c) rear view showing the configuration of the cable-type column 12 of Example 4. It is a figure which shows the winding state of the inner cables 20c and 20d to both the cable pulleys 20a and 20b. It is sectional drawing of the spring 20j for cable friction adjustment. It is (a) perspective view, (b) side view, and (c) plan view showing an example of cable routing to a vehicle. FIG. 10 is a cross-sectional view illustrating a configuration of a cable column according to a fifth embodiment. It is a figure which shows the difference of the length of the spring 20j for cable tension adjustment in the initial state of the inner cable 20c (20d), and the maximum extension state. 10 is a cross-sectional view showing a configuration of a cable-type column of Example 6. FIG. It is S25-S25 sectional drawing of FIG. FIG. 10 is an overall system diagram illustrating a vehicle steering apparatus according to a seventh embodiment. FIG. 10 is a control block diagram of a controller 14 according to a seventh embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Steering wheel 2 Operation part 3 Steering wheel 4 Steering part 5 Reaction force torque sensor 6 Reaction force actuator 7 Column shaft 8 Steering actuator 9 Steering torque sensor 10 Pinion shaft 11 Steering mechanism 12 Cable type column 13 Vehicle speed sensor 14 Controller 15 Steering angle sensor 16 Steering angle sensor 17 Current servo 18 Current servo

Claims (14)

An operation unit having an operation input means and a steering unit for steering a steered wheel are connected directly or indirectly via a cable column,
Steering torque detection means for detecting steering torque input to the operation unit;
A steering actuator that outputs a steering assist force to the steering unit;
Steering control means for controlling a steering actuator according to a steering torque input to the operation unit;
Vehicle speed detection means for detecting the vehicle speed;
A reaction force actuator that outputs a steering reaction force to the operation unit;
In a vehicle steering apparatus comprising:
Steering torque detection means for detecting the steering torque input to the steering unit;
Reaction force control means for controlling a reaction force actuator only in accordance with the vehicle speed and the steering torque;
Provided ,
The cable column is
A steering side cable pulley provided in the operation section;
A steered wheel side cable pulley provided in the steered portion;
Two inner cables that are connected to both cable pulleys while being wound in opposite directions;
A first pulley case for accommodating the steering side cable pulley;
A second pulley case for housing the steering wheel side cable pulley;
Two outer tubes covering both inner cables and connecting both pulley cases;
Have
A vehicular steering apparatus , wherein an extendable member that covers the inner cable is provided between at least one end of the two outer tubes and the pulley case . The vehicle steering apparatus according to claim 1,
When the inner cable is wound around the cable pulley of the pulley case in contact with the elastic member, the elastic force of the elastic member is set so that the outer tube is not displaced toward the pulley case. A vehicle steering apparatus. The vehicle steering apparatus according to claim 1 or 2,
The elastic force of the elastic member is set to be equal to or greater than the maximum frictional sliding resistance force generated between the inner cable and the outer tube in the maximum extension state of the inner cable. Steering device. The vehicle steering apparatus according to any one of claims 1 to 3 ,
A vehicular steering apparatus, wherein the elastic force of the expansion and contraction member is set to be equal to or greater than a maximum frictional sliding resistance force generated between the inner cable and the outer tube in an initial state when mounted on a vehicle. . An apparatus as claimed in any one of claims 1 to 4,
The vehicular steering apparatus according to claim 1, wherein the elastic force of the telescopic member is set so that the amount of deflection of the outer tube is not more than a predetermined value in the maximum extension state of the inner cable. An apparatus as claimed in any one of claims 1 to 5,
A vehicular steering apparatus comprising: a contraction displacement restricting means that permits displacement of the expansion member in the expansion direction and restricts displacement in the contraction direction. The vehicle steering apparatus according to claim 1 ,
For the vehicle, the expansion member has a larger expansion rate with a larger total bending angle, which is a sum of bending angles of the bent portions of the outer tube, larger than a expansion rate with a smaller total bending angle. Steering device. The vehicle steering apparatus according to claim 1 or 7 ,
The vehicular steering apparatus according to claim 1, wherein the expansion / contraction member sets the expansion / contraction ratio to be larger as the cable friction is larger. The vehicle steering apparatus according to claim 1 ,
A pulley torque detecting means for calculating a pulley torque acting on the steering side cable pulley based on the current value of the reaction force actuator and the steering torque;
The vehicle steering apparatus, wherein the steering control means controls the steering actuator based on the pulley torque. The vehicle steering apparatus according to any one of claims 1 to 9 ,
A steering apparatus for a vehicle, wherein the steering torque detecting means is provided between a steering actuator and a steered wheel. The vehicle steering apparatus according to any one of claims 1 to 10, wherein:
The steering control device controls the steering actuator so that the absolute value of the difference between the steering torque and the steering torque is equal to or less than the no-load sliding torque. The vehicle steering apparatus according to any one of claims 1 to 11, wherein:
The steering control means controls the steering actuator so that the tension of the inner cable constituting the cable column is equal to or less than the inner cable endurance limit or the outer tube endurance limit, whichever is smaller. A vehicle steering apparatus. The vehicle steering apparatus according to any one of claims 1 to 12,
In place of the steering torque detecting means, a steering angle detecting means for detecting the steering angle of the operation section and a turning angle detecting means for detecting the turning angle of the turning section are provided.
The steering control device controls a steering actuator according to a steering angle and a steering angle. The vehicle steering apparatus according to claim 13 , wherein
The steering angle detection means is a steering side angle sensor that detects a rotation angle of the steering side cable pulley,
The steered angle detecting means is a steered wheel side angle sensor that detects a rotation angle of a steered portion side cable pulley.

Images