JP2015091676A - Vehicular steering apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a vehicular steering apparatus capable of reliably engaging a clutch mechanism, preventing the aforementioned failure.SOLUTION: A vehicular steering apparatus 11 is a steer-by-wire steering apparatus. When a vehicle speed is low, a steering angle ratio that is a ratio of a steering angle to a steering-operation angle is increased (quick). In this case, however, when the steering angle is nearly a maximum steering angle, the steering angle ratio is decreased (slow) compared to the case of a steering angle being far from the maximum steering angle, and specifically, is set closer to a mechanical steering angle when a steering-operation shaft 23 side and a steering shaft 25 side are connected by a clutch mechanism 19.

Description

  Vehicle steering system

In Steer By Wire, the ratio of the tire steering angle (steering angle) to the steering angle (steering angle) (steering angle ratio) can be set freely. Normally, the steering angle ratio is set based on the vehicle speed, and is set to a quick steering angle ratio at a low vehicle speed and a slow steering angle ratio at a high vehicle speed.
In a steer-by-wire system that does not mechanically connect the steering system and the wheel steering system, the steering wheel is more than necessary unless mechanical restrictions are provided. Can steer.

  In order to prevent such inconvenience, Patent Document 1 discloses that “a steering mechanism that does not mechanically connect a steering system and a wheel steering system, a steering angle control unit, and a steering reaction force control unit”. In the vehicle steering control apparatus, an angle sensor for detecting a steering angle is provided, and the steering reaction force control unit is configured to perform steering steering until the steering steering angle reaches a limit angle from a predetermined steering angle. A steering limit reaction force control unit is provided that increases the steering reaction force with a slope of a straight line or a curve in accordance with the increase of the angle, and rapidly increases the steering reaction force to the limit reaction force when the steering angle reaches the limit angle. The vehicle steering control device is disclosed.

JP 2004-224159 A

By the way, as described above, the steering angle ratio is generally set based on the vehicle speed, and is generally set to a quick steering angle ratio at a low vehicle speed and a slow steering angle ratio at a high vehicle speed. Therefore, at low vehicle speed, the rack of the steering gear box moves at high speed. Therefore, when steering to the maximum turning angle with a quick steering angle ratio at a low vehicle speed, the rack end easily collides with the housing of the steering gear box, and the impact tends to increase.
Therefore, an object of the present invention is to provide a vehicle steering apparatus capable of suppressing an impact when a rack end collides with a housing in a steering gear box.

One aspect of the present invention includes a steering unit that performs an operation for steering a vehicle, a steering mechanism that steers the steered wheels of the vehicle without being connected to the steering unit, the steering unit side, and the steering mechanism. A clutch mechanism that connects / disconnects to the side, a steering angle ratio control unit that controls a steering angle ratio that is a steering amount by the steering mechanism according to an operation amount of the steering unit, and a steering rotation amount that is detected by the steering unit A steering rotation amount detection unit for detecting the vehicle speed of the vehicle, and the steering angle ratio control unit is configured such that the vehicle speed is less than a first value and the turning amount is greater than or equal to a second value. In this case, the steering device for a vehicle controls the steering angle ratio so that the steering amount corresponding to the operation amount is smaller than that when the steering angle ratio is less than the second value.
According to the present invention, when the steered amount is large at the stop speed, it is possible to reduce the rudder angle ratio and suppress the impact when the rack end collides with the housing in the steering gear box.

Another aspect of the present invention includes a steering unit that performs an operation for steering the vehicle, a steering mechanism that steers the steered wheels of the vehicle without being connected to the steering unit, the steering unit side, and the rolling unit. A clutch mechanism that connects and disconnects the rudder mechanism side, a rudder angle ratio control unit that controls a rudder angle ratio that is a steered amount by the steered mechanism according to an operation amount of the steering unit, and a steering rotation amount by the steered unit A steering rotation amount detection unit for detecting the vehicle speed, and a vehicle speed detection unit for detecting the vehicle speed of the vehicle, wherein the steering angle ratio control unit is configured such that the vehicle speed is less than a first value and the turning amount is a second value. When the value is greater than or equal to the value, the steering angle ratio is made closer to the steering angle ratio when the steering unit side and the steering mechanism side are connected by the clutch mechanism, compared to when the value is less than the second value. A vehicle steering apparatus to be controlled.
According to the present invention, when the steered amount is large at the stop speed, the steering angle ratio is made close to the steered angle ratio when the steering unit side and the steered mechanism side are connected to each other in the rack in the steering gear box. It is possible to suppress an impact when the end and the housing collide.

  ADVANTAGE OF THE INVENTION According to this invention, the steering apparatus for vehicles which can suppress the impact when a rack end and a housing collide in a steering gear box can be provided.

FIG. 1 is a diagram showing an overall schematic configuration of a vehicle steering apparatus according to an embodiment of the present invention. FIG. 2 is a graph illustrating processing performed by the steering angle ratio control unit of the vehicle steering apparatus according to the embodiment of the present invention. FIG. 3 is a graph illustrating another example of processing performed by the steering angle ratio control unit of the vehicle steering apparatus according to the embodiment of the present invention.

Hereinafter, an embodiment of the present invention will be described.
FIG. 1 is a schematic configuration diagram of a vehicle steering apparatus according to the present embodiment.
The vehicle steering device 11 is a steer-by-wire (SBW) type steering device. The vehicle steering device 11 has a function (SBW mode) for generating a steering force by driving a steering motor 29 described later (SBW mode), for example, when the steering reaction motor 16 fails, the driver is driven by the steering motor 29. When an electric power steering (EPS) function (EPS mode) for generating an assisting force related to manual steering of the vehicle, and for example, a failure of the steering reaction force motor 16 and the steering motor 29, the driver's manual (Manual steering mode).

In order to realize the above functions, the vehicle steering device 11 includes a steering wheel (handle) 13, a steering reaction force generating device 15, a steering device 17, a clutch mechanism 19, and the like as shown in FIG. . The vehicle steering device 11 is mounted on the vehicle V. The vehicle V includes a pair of steered wheels 21a and 21b.
The handle 13 (steering unit) is a member for steering the vehicle V that is operated according to the driver's driving intention. A steering shaft 23 is provided on the handle 13. The steering shaft 23 is configured to rotate around the shaft in accordance with the operation of the handle 13 by the driver.

  The steering reaction force generation device 15 generates a reaction force (response) related to steering, that is, a steering reaction force at the driver's hand holding the handle 13 when the vehicle steering device 11 is operating in the SBW mode. Have The steering reaction force generator 15 has a steering reaction force motor 16. A steering shaft 23 is connected to the steering reaction force motor 16. The steering reaction force motor 16 generates a steering torque for rotating the steering shaft 23 around the axis. Thus, when the vehicle steering device 11 is operating in the SBW mode, a reaction force (responsiveness) related to the steering is transmitted to the hand of the driver who holds the handle 13.

  The steered device (steering gear box) 17 has a function of converting the rotational motion of the steered shaft 25 into linear motion of the rack shaft 27 via a well-known rack and pinion mechanism (not shown). In this rack and pinion mechanism, the rack and the pinion mesh with each other and are housed in the housing of the steering gear box 17. The rack is formed on the rack shaft 27. The steering device 17 has a steering motor 29. A steered shaft 25 and a rack shaft 27 are connected to the steered motor 29. The turning motor 29 generates a turning torque for causing the rack shaft 27 to linearly move along the axial direction. A pair of steered wheels 21a and 21b are connected to the rack shaft 27 via tie rods (not shown). The pair of steered wheels 21 a and 21 b are steered by the linear motion of the rack shaft 27.

The steered device 17 having the steered shaft 25, the rack shaft 27, and the steered motor 29 corresponds to the “steering mechanism” of the present invention.
The clutch mechanism 19 has a function of connecting or disconnecting the steering shaft 23 and the steered shaft 25. In order to realize such a function, the clutch mechanism 19 includes a planetary gear mechanism 31. The planetary gear mechanism 31 includes an internal gear 31a, a planetary gear 31b, a sun gear 31c, and a planet carrier 31d.
The clutch mechanism 19 includes a locking gear 33 and a locking device 35. The lock device 35 includes a lock pin 39 that engages with a tooth groove of the lock gear 33 and an electromagnetic solenoid 37 that drives the lock pin 39.

The internal gear 31 a is fixed to the lower end side of the steering shaft 23 and is configured to rotate integrally with the steering shaft 23. The sun gear 31c is configured to freely rotate around a rotation axis coaxial with the steered shaft 25. A plurality of planetary gears 31b are provided so as to engage with each of the sun gear 31c and the internal gear 31a. Each of the plurality of planetary gears 31b is rotatably supported with respect to a planet carrier 31d that rotates integrally with the steered shaft 25.
The locking gear 33 is an external gear. The locking gear 33 is configured to rotate integrally with the sun gear 31c. The lock pin 39 is urged in a direction approaching the lock gear 33 by an urging means (not shown). When the lock pin 39 is engaged with the tooth groove of the locking gear 33, the rotational movement of the locking gear 33 is restricted.

The electromagnetic solenoid 37 operates to release the engagement between the lock pin 39 and the locking gear 33 by displacing the lock pin 39 by supplying an exciting current.
The locking device 35 is configured to operate according to a control signal sent from the control device 40. The control device 40 operates to release the engagement of the lock pin 39 with the lock gear 33 by supplying an excitation current to the electromagnetic solenoid 37.

Next, the operation of the clutch mechanism 19 will be described. When the lock pin 39 engages with the tooth groove of the locking gear 33, the rotational movement of the sun gear 31c that rotates integrally with the locking gear 33 is restricted.
When the driver operates the handle 13 in a state where the rotational movement of the sun gear 31 c is restricted, the internal gear 31 a rotates as the steering shaft 23 rotates. At this time, since the rotational movement of the sun gear 31c is restricted, the planetary gear 31b revolves around the sun gear 31c while rotating. Due to the revolution of the planetary gear 31b, the planetary carrier 31d that pivotally supports the planetary gear 31b and the turning shaft 25 that rotates integrally with the planetary carrier 31d rotate.
In short, in a state where the electromagnetic solenoid 37 is OFF and the lock pin 39 is engaged with the tooth groove of the locking gear 33, the clutch mechanism 19 is in a coupled state in which the steering shaft 23 and the steered shaft 25 are coupled. At this time, the rotational force of the steering shaft 23 is transmitted to the steered shaft 25.

On the other hand, when the electromagnetic solenoid 37 is turned on and the engagement of the lock pin 39 with the tooth groove of the lock gear 33 is released, the sun gear 31c that rotates together with the lock gear 33 becomes rotatable. .
When the driver operates the handle 13 with the sun gear 31c being rotatable, the internal gear 31a is rotated with the rotation of the steering shaft 23. At this time, the planetary gear 31b tries to revolve around the sun gear 31c while rotating. However, the steered wheels 21 a and 21 b are connected to the planetary carrier 31 d via the steered shaft 25 and the rack shaft 27. For this reason, the resistance force against the rotation of the planet carrier 31d is much larger than the resistance force against the rotation of the sun gear 31c in a rotatable state. Therefore, when the planetary gear 31b rotates, the sun gear 31c rotates (rotates), and the planet carrier 31d does not rotate. That is, the steered shaft 25 does not rotate.
In short, when the electromagnetic solenoid 37 is turned on and the engagement of the lock pin 39 with the tooth groove of the locking gear 33 is released, the clutch mechanism 19 disconnects the steering shaft 23 and the steered shaft 25 from each other. It becomes a separated state. At this time, the rotational force of the steering shaft 23 is not transmitted to the steered shaft 25.

Next, an input / output system for the control device 40 will be described.
A steering angle sensor 41, a steering torque sensor 43, a steering reaction force motor resolver 45, a steered motor resolver 47, a rack stroke sensor 49, and a vehicle speed sensor 51 are connected to the control device 40 as an input system.
The steering angle sensor 41 and the steering torque sensor 43 are provided on the steering shaft 23. The steering angle sensor 41 (steering rotation amount detection unit) detects the steering rotation amount (steering angle) of the handle 13 by the driver, and gives the detected steering angle information to the control device 40.

The steering torque sensor 43 detects the steering torque of the handle 13 by the driver, and provides the detected steering torque information to the control device 40.
The steering reaction force motor resolver 45 is provided in the steering reaction force motor 16. The steering reaction force motor resolver 45 detects the rotational operation amount (steering angle) of the steering reaction force motor 16 and supplies the detected steering angle information to the control device 40.
The steered motor resolver 47 is provided in the steered motor 29. The steered motor resolver 47 detects the rotational operation amount (steered angle) of the steered motor 29 and provides the detected steered angle information to the control device 40.

The rack stroke sensor 49 is provided on the rack shaft 27. The rack stroke sensor 49 detects the linear movement amount (steering angle) of the rack shaft 27 and provides the detected turning angle information to the control device 40.
The vehicle speed sensor 51 (vehicle speed detection unit) detects the speed (vehicle speed) of the vehicle V and gives the detected vehicle speed information to the control device 40.
On the other hand, the control device 40 is connected to the steering reaction force motor 16, the steered motor 29, and the electromagnetic solenoid 37 as an output system.

Next, the contents of control executed by the control device 40 will be described.
The control device 40 determines the operation mode of the vehicle steering device 11 based on the detection signal input via the input system and the abnormality diagnosis result related to various components of the vehicle steering device 11, such as the SBW mode and the EPS. A control signal for controlling the driving of the steering reaction force motor 16, the steering motor 29, and the electromagnetic solenoid 37 is generated in accordance with the function for determining either the mode or the manual steering mode and the determined operation mode. And a function of performing drive control of the steering reaction force motor 16, the steered motor 29, and the electromagnetic solenoid 37 based on the generated control signal.

The control device 40 controls the steering reaction force motor 16 when the vehicle steering device 11 is operating in the SBW mode, thereby preventing the driver's hand holding the handle 13 from reacting to appropriate steering. Try to convey power (response).
The control device 40 also steers the steered wheels 21a and 21b according to the driver's driving intention by performing drive control of the steered motor 29 when the vehicle steering device 11 is operating in the SBW mode. To work.

Further, the control device 40 controls the state of the clutch mechanism 19 in the coupled state by performing drive control for switching the supply or stop of the excitation current to the electromagnetic solenoid 37 according to the operation mode of the vehicle steering device 11. Or it operates so that it may switch to either one of a separation state. That is, in the SBW mode, the electromagnetic solenoid 37 is turned on and the clutch mechanism 19 is disconnected, and in the EPS mode and the manual steering mode, the electromagnetic solenoid 37 is turned off and the clutch mechanism 19 is connected.
When the operation mode is the SBW mode, the control device 40 detects the ratio of the tire steering angle (steering angle) to the steering wheel steering angle (steering angle) (steering angle ratio) by the vehicle speed sensor 51. The vehicle is controlled so that it is quick when the vehicle speed is low and slow when the vehicle speed is high.

  The control device 40 controls the size of the maximum steering angle (maximum steering angle) according to the vehicle speed of the vehicle V detected by the vehicle speed sensor 51. Then, when the steering angle detected by the steering angle sensor 41 becomes the maximum steering angle, the control device 40 suddenly generates a large reaction force (wall reaction force) by the steering reaction force motor 16, and the maximum steering angle is determined. The steering beyond the limit is made impossible. Thus, the maximum steering angle is electrically defined, and no means for mechanically defining is provided. On the other hand, in the vehicle steering device 11, the maximum turning angle (maximum tire steering angle) is mechanically determined by the above-described mechanism and is always constant. That is, the maximum steering angle is set differently from the maximum steering angle.

The control device 40 includes a motor temperature management unit 61. The motor temperature management unit 61 manages the temperature of the steering reaction force motor 16 and the steered motor 29 so as not to become too high. That is, the motor temperature management unit 61 determines the temperatures of the steering reaction force motor 16 and the steering motor 29. Specifically, the integrated value per hour of the motor current is obtained and the temperature is estimated. Alternatively, a temperature sensor may be provided in each of the steering reaction force motor 16 and the steered motor 29 to directly detect the motor temperature.
When the temperature of the steering reaction force motor 16 or the steered motor 29 becomes equal to or higher than the predetermined value t1, the motor temperature management unit 61 controls the motor output to be limited to a predetermined degree.

After that, when the temperature of the steering reaction force motor 16 or the steering motor 29 further exceeds a predetermined value t2 (> t1), the electromagnetic solenoid 37 is turned OFF and the lock pin 39 is engaged with the teeth of the lock gear 33. Make sure to engage with the groove. Thereby, the clutch mechanism 19 will be in the coupling state which couple | bonds the steering shaft 23 side and the steered shaft 25 side. Thereby, the motor temperature management unit 61 shifts the operation mode from the SBW mode to the EPS mode. Thereby, the output of the steering reaction force motor 16 or the steering motor 29 is further reduced.
By reducing the output of the steering reaction force motor 16 or the turning motor 29, the temperature of the steering reaction force motor 16 and the turning motor 29 can be lowered so that the motor temperature does not become excessively high.

The control device 40 includes a maximum steering angle restriction unit 62. As described above, the maximum steering angle is variable in accordance with the vehicle speed, and the control device 40 electrically restricts the steering beyond the maximum steering angle by the wall reaction force generated by the steering reaction force motor 16. Yes. However, if the driver operates the handle 13 with a strong force, the wall reaction force may be overcome.
Therefore, when the steering angle (steering wheel steering angle) detected by the steering angle sensor 41 exceeds the reference value θ1, the maximum steering angle restricting unit 62 turns off the electromagnetic solenoid 37 and connects the lock pin 39 to the locking gear 33. And the clutch mechanism 19 is controlled to be engaged.
Thereby, since the steering shaft 23 side and the steered shaft 25 side are coupled, the rotation of the handle 13 is restricted by the maximum turning angle that is mechanically determined. Therefore, it is possible to prevent the handle 13 from being operated at an excessively large rotation angle and to prevent a cable reel (not shown) provided on the handle 13 from being cut by an excessively large rotation of the handle 13. it can.

Further, the control device 40 includes a steering angle ratio control unit 63. The steering angle ratio control unit 63 determines whether or not the vehicle speed detected by the vehicle speed sensor 51 is less than the reference value s (first value) in the SBW mode. The steering angle ratio control unit 63 also determines whether or not the tire steering angle (steering angle) detected by the rack stroke sensor 49 (or the steering motor resolver 47) is equal to or greater than the reference steering angle δ2 (second value). To do.
As described above, in the SBW mode, the ratio of the steering angle to the steering angle (steering angle ratio) is controlled so as to be quick when the vehicle speed of the vehicle V is low and slow when the vehicle speed is high. Therefore, when the vehicle speed is less than the reference value s, the steering angle ratio is quicker than when the vehicle speed is greater than or equal to the reference value s.
However, even when the vehicle speed is less than the reference value s, the steering angle ratio control unit 63, if the turning angle is greater than or equal to the reference value δ2, compared to when the turning angle is less than the reference turning angle δ2. Control the steering angle ratio to be small (slower). That is, even at the same low vehicle speed, when the turning angle is close to the maximum turning angle, switching from quick to slow is performed.

  FIG. 2 is a graph for explaining the change in the steering angle ratio with respect to the turning angle under the control of the steering angle ratio control unit 63. That is, in the graph of FIG. 2 (the same applies to FIG. 3 described later), the horizontal axis indicates the steering angle, and the vertical axis indicates the steering angle ratio. And the rudder angle ratio on the vertical axis becomes quicker as it goes up and slows down as it goes down. As described above, when the vehicle V is at a low vehicle speed (when the vehicle speed is less than the reference value s), control is performed so that the turning angle (and hence the steering angle ratio) is relatively large with respect to the steering angle ( quick). FIG. 2 shows the vehicle V when the vehicle speed is low. However, even in this case, when the turning angle becomes equal to or larger than the reference turning angle δ2, the steering angle ratio becomes smaller (that is, the vehicle becomes slow) than when the turning angle is smaller than that (reference numeral 291). To control). Specifically, in the case of reference numeral 292, compared to the case of reference numeral 291, the steering angle ratio (mechanical steering angle) determined mechanically when the steering shaft 23 side and the steered shaft 25 side are connected by the clutch mechanism 19. (In the example of FIG. 2, the steering angle ratio in the case of reference numeral 292 is matched with the mechanical steering angle ratio).

Instead of the example of FIG. 2, control may be performed as in the example of FIG. In the example of FIG. 3, when the turning angle becomes equal to or larger than the reference turning angle δ2, the steering angle ratio is gradually reduced as the turning angle approaches the maximum turning angle. In the examples of FIGS. 2 and 3, the details of the steering angle ratio when the turning angle is less than the reference turning angle δ2 are omitted. It can be controlled to change according to the size of the lateral G.
Thus, according to the vehicle steering device 11 of the present embodiment, even in the case where the vehicle V is performing the quick control at the low vehicle speed (less than the reference value s) in the SBW mode, the turning angle. Is near the maximum turning angle (reference turning angle δ2 or more), the steering angle ratio is reduced (slow).
That is, the rack (not shown) of the rack and pinion mechanism in the steering gear box (steering device) 17 moves at a high speed in the SBW mode when the vehicle is quick at a low vehicle speed.

However, in this embodiment, even in the case of a quick at a low vehicle speed, the steering angle ratio control unit 63 controls the steering angle ratio to be slow when the turning angle is in the vicinity of the maximum turning angle (reference steering angle δ2 or more). Therefore, the movement of this rack becomes low speed near the maximum turning angle.
Therefore, the collision of the rack end with the housing of the steering gear box 17 can be suppressed, and the impact can be reduced.
Further, the steering angle ratio in this case is close to the steering angle ratio (mechanical steering angle ratio) that is mechanically determined when the steering shaft 23 side and the steered shaft 25 side are coupled by the clutch mechanism 19 (FIG. 2). An example of matching is shown). Therefore, even when the wall reaction force is overcome and the steering angle exceeds the maximum steering angle and the clutch mechanism 19 is coupled, it is possible to prevent the driver from feeling uncomfortable with steering.

11 Vehicle Steering Device 13 Handle (Steering Section)
17 Steering device (steering mechanism)
19 Clutch mechanism 25 Steering shaft (steering mechanism)
27 Rack shaft (steering mechanism)
41 Steering angle sensor (steering rotation amount detection unit)
51 Vehicle speed sensor (vehicle speed detector)

Claims (2)

A steering unit that performs operations for steering the vehicle;
A steering mechanism that steers the steered wheels of the vehicle without being connected to the steering unit;
A clutch mechanism for connecting and disconnecting the steering unit side and the steering mechanism side;
A steering angle ratio control unit that controls a steering angle ratio that is a steering amount by the steering mechanism according to an operation amount of the steering unit;
A steering rotation amount detection unit for detecting a steering rotation amount by the steering unit;
A vehicle speed detector for detecting the vehicle speed of the vehicle;
With
The steering angle ratio control unit controls the steering angle ratio when the vehicle speed is less than a first value and the turning amount is greater than or equal to a second value, compared to when the vehicle speed is less than the second value. A vehicle steering apparatus that performs control so that the steering amount corresponding to the amount is reduced. A steering unit that performs operations for steering the vehicle;
A steering mechanism that steers the steered wheels of the vehicle without being connected to the steering unit;
A clutch mechanism for connecting and disconnecting the steering unit side and the steering mechanism side;
A steering angle ratio control unit that controls a steering angle ratio that is a steering amount by the steering mechanism according to an operation amount of the steering unit;
A steering rotation amount detection unit for detecting a steering rotation amount by the steering unit;
A vehicle speed detector for detecting the vehicle speed of the vehicle;
With
The steering angle ratio control unit sets the steering angle ratio when the vehicle speed is less than a first value and the turning amount is greater than or equal to a second value compared to when the vehicle speed is less than the second value. A vehicle steering device that controls the steering unit side and the steering mechanism side to be close to a steering angle ratio when the mechanism is connected.

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