JP3006686B2 - Steering angle correction device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention is directed to a method in which a driver turns a front wheel via a steering wheel, and further corrects and steers a steered wheel according to running conditions of a vehicle. The present invention relates to a steering angle correction device capable of performing the following.

(Prior Art) In a commonly used steering device, a handle shaft 1a is connected to a handle 1, as shown in FIG.

A pinion PG is provided at the tip of the handle shaft 1a. A rack R that engages with the pinion PG and converts the rotational motion of the pinion PG into horizontal motion is provided. The front end of the rack R is connected to the front wheels 7, 8 via side rods 3, 4 and knuckle arms 5, 6. It is linked to

Now, when the handle 1 is rotated, this torque rotates the pinion PG via the handle shaft 1a. This pinion PG
Is converted into horizontal motion by the rack R and transmitted to the side rods 3 and 4 and the knuckle arms 5 and 6.

The front wheels 7, 8 are steered by the movement of the knuckle arms 5, 6, and the vehicle turns.

(Problems to be Solved by the Present Invention) In general, it is known that, in a vehicle in which the steering characteristic tends to understeer, the turning radius decreases as the vehicle speed increases.

It is known that a turning radius of a vehicle having a steering characteristic that tends to be oversteer decreases as the vehicle speed increases.

That is, in order to keep the turning radius constant even when the vehicle speed changes, it is necessary to perform corrected steering of the front wheels and further increase or return the steering angle of the front wheels.

For this reason, in the conventional device configured as described above, the driver must perform the correction steering of the front wheels by himself. For this reason, there is a problem that an unskilled driver cannot perform the correction steering and encounters a danger.

An object of the present invention is to provide a steering angle correction device capable of correcting and steering a steered wheel without a driver turning a steering wheel by himself.

(Means for Solving the Problems) The present invention provides a front wheel steering mechanism for steering front wheels, a rear wheel steering mechanism for steering rear wheels, and a controller for controlling the front wheel steering mechanism and the rear wheel steering mechanism. A steering wheel rotation angle sensor that detects a steering wheel operation angle and outputs a steering wheel rotation angle signal, a vehicle speed sensor that detects vehicle speed and outputs a vehicle speed signal, and a front wheel steering angle signal that detects a front wheel steering angle. A front wheel turning angle sensor that outputs a front wheel turning angle, and a rear wheel turning angle sensor that detects a front wheel turning angle and outputs a rear wheel turning angle signal. It comprises a pinion shaft linked with a pinion, a universal joint that swingably connects these two shafts, a correction motor, and a transmission mechanism that moves the pinion shaft parallel to the rack by rotation of the correction motor, By controller In the turning angle correction device for controlling the output of the correction motor to correct the front wheels to a desired turning angle, the controller includes a rear wheel turning angle target based on the front wheel turning angle signal and the vehicle speed signal. A rear wheel turning angle output signal is obtained from the rear wheel turning angle target value and the rear wheel turning angle signal, and the rear wheel turning mechanism is controlled by the rear wheel turning angle output signal to control the rear wheel turning mechanism. The steering angle is corrected, and a front wheel turning angle target value is determined based on the rear wheel turning angle target value and the rear wheel turning angle signal. From the front wheel turning angle target value and the front wheel turning angle signal, A front wheel turning angle output signal is obtained, and the front wheel turning mechanism is controlled by the front wheel turning angle output signal to correct the front wheel turning angle.

(Operation of the Present Invention) The device as described above performs the correction steering of the rear wheels in the same direction as the steering direction of the front wheels when the vehicle speed increases during turning, and the vehicle speed decreases when the vehicle speed decreases. Corrects and turns the rear wheels in the direction opposite to the turning direction of the front wheels. By correcting and steering the rear wheel in this manner, the side slip angle of the rear wheel is set to zero.

However, if the rear wheels are corrected and steered in the same direction as the front wheels as described above, the turning radius of the vehicle increases. Further, when the rear wheels are steered in the opposite direction to the front wheels, the turning radius of the vehicle is reduced.

Therefore, the front wheels are also corrected and steered according to the corrected steering of the rear wheels.

That is, when the rear wheels are corrected and steered in the same direction as the front wheels, the front wheels are further corrected and steered in the same direction. When the rear wheel is steered in the opposite direction to the front wheel, the front wheel is steered in the opposite direction.

(Effects of the Present Invention) According to the present invention, even if the driver does not turn the steering wheel, the front wheel and the rear wheel are corrected and steered,
A change in turning radius caused by a change in vehicle speed can be prevented.

That is, an oversteer vehicle can correct and steer in a direction to cancel the oversteer.

Further, in an understeer vehicle, the vehicle can be steered in a direction to cancel the understeer.

As described above, since the turning radius can be kept constant even when the vehicle speed changes, even an inexperienced driver can drive safely.

The front wheels are corrected and steered by moving the pinion shaft parallel to the rack, so that the steering wheel does not turn during correction.

Therefore, the driver does not feel uncomfortable.

(Embodiment of the Present Invention) In the first embodiment shown in FIGS. 1 and 2, an input shaft 1b connected to a handle 1 is connected to a pinion shaft 1c via a universal joint 28. The pinion shaft 1c rotates integrally with the input shaft 1b and is swingable with respect to the input shaft 1b. The pinion 21 is provided at the tip of the pinion shaft 1c.

The pinion shaft 1c is supported by a bearing 29 provided on the wall surface of the gear case 30 and has a tip portion formed by a pinion 21.
Together with the gear case 30.

The pinion 21 meshes with the rack 22 and converts the rotational movement of the pinion 21 into a horizontal movement of the rack 22. The horizontal movement of the rack 22 is transmitted to the front wheels 7 and 8 via the side rods 3 and 4 and the knuckle arms 5 and 6 that are continuous with the rack 22, and steers the front wheels 7 and 8 left and right.

Further, the gear case 30 is provided slidably in the horizontal direction of the rack 22, and the gear case 30 is connected to the motor 2 via a lever 23, a worm wheel 24, and a worm 25.
6 is connected to the motor shaft 27.

The motor 26 is connected to the controller P, and outputs the front wheel steering output signal I _Mf sent from the controller P.
The motor shaft 27 is rotated according to.

When the motor shaft 27 of the motor 26 rotates, the worm wheel 24 rotates via the worm 25.

Since the worm wheel 24 is provided with the lever 23 at a point B offset from the center A, the rotational movement of the worm wheel 24 is converted into the horizontal movement of the lever 23. The horizontal movement of the lever 23 causes the gear case 30 to move horizontally as a whole in the left-right direction in the drawing.

Now, the rotation of the motor shaft 27 of the motor 26
When 30 moves in the left-right direction in the figure, it is pushed by a bearing 29 provided on the wall surface of the gear case 30, and the pinion shaft 1c swings around the universal joint 28 as a fulcrum. At this time, the pinion shaft 1c is
It doesn't come up because of being held down. Therefore, the pinion 21 is kept in a state of being meshed with the rack 22.
In this state, if the pinion shaft 1c swings, the pinion 21 pushes the rack 22 in the left-right direction without rotating. In other words, during turning, the driver holds the steering wheel 1 firmly and stops the rotation of the pinion 21,
When the pinion shaft 1c swings, the rack 22 moves in parallel.

By moving the rack 22 in this manner, the front wheels 7, 8 are corrected and steered via the side rods 3, 4, and the knuckle arms 5, 6.

 The front wheel steering mechanism is configured as described above.

A handle rotation angle sensor 31 that detects the rotation angle of the handle 1 and outputs a handle rotation angle signal θs is disposed on the handle shaft 1a.

Further, near the side rods 3 and 4, a front wheel turning angle sensor 32 that detects a turning angle of the front wheels and outputs a front wheel turning angle signal θf is arranged.

Further, in this device, a vehicle speed sensor 33 that detects a vehicle speed and outputs a vehicle speed signal V is arranged.

The steering wheel rotation angle sensor 31, the front wheel turning angle sensor 32, and the vehicle speed sensor 33 are each connected to the controller P.

The controller P determines a rear wheel turning angle target value _r according to the front wheel turning angle signal θf and the vehicle speed signal V sent from the front wheel turning angle sensor 32 and the vehicle speed sensor 33. Furthermore, compared with the wheel steering angle signal theta _r after which represents the turning angle of the actual rear wheel and the rear wheel steering angle target value _r, and determines an output signal I _Mr, front wheel steering angle output signal I _Mf Is determined.

Here, a rear wheel steering mechanism 9 provided at the rear of the vehicle is a motor.
34, a reduction gear 35, a pinion 36, a rack 37, and side rods 38, 39 as main elements.

The motor shaft 40 of the motor 34 is provided with a pinion 36 at its tip via a reduction gear 35. This pinion
The 36 meshes with the rack 37 and converts the rotational motion of the motor shaft 40 into a horizontal motion.

The rack 37 is connected to the rear wheels 4 via side rods 38 and 39.
It is connected to 1,42.

The rear wheel turning mechanism 9 configured as described above rotates the motor shaft 40 of the motor 34 when the rear wheel turning output signal I _Mr is input from the controller P.

When the motor shaft 40 of the motor 34 rotates, the rotational force is reduced via the reduction gear 35, and the pinion 36 is rotated.
The rotational movement of the pinion 36 is converted into a horizontal movement by a rack 37, and the rear wheels 41,
Steer 42.

Then, in the vicinity of the side rods 38 and 39 detects a steering angle of the rear wheels, and a wheel steering angle sensor 43 after outputting a rear wheel steering angle signal theta _r provided. The rear wheel turning angle sensor 43 is connected to the controller P.

The controller P, is compared with the wheel steering angle signal theta _r and the rear wheel steering angle target value _r was detected in the rear wheel steering angle sensor 43, calculates whether the rear wheel is controlled to the target as the rear wheel steering The output signal I _Mr is determined.

Then, the rear wheel turning output signal I _Mr is transmitted to the rear wheel turning mechanism 9.
And the rear wheels are steered so that the target steering angle is obtained.

The rear wheel turning angle target value _r is determined by the following equation (1).

_r = kθ _f (1) Here, θ _f is a front wheel turning angle signal, and k is a front and rear wheel turning ratio.

Then, the rear wheel turning output signal I _Mr is determined by the following equation (2).

In _{I Mr = l r Δθ r +} m r · dΔθ r / dt + n t ∫Δθ r dt ... (2) _{where, l r, m r, n} r is a constant, [Delta] [theta] _r is rotary rear and the rear wheel steering angle target value _r which is the difference between the steering angle signal θ _r.

The first term l _r Δθ _r is a term that outputs a current proportional to the deviation, and outputs a large current proportional to the deviation when the deviation between the target value and the actual steering angle is large. If they match, the current becomes zero.

The second term, m _r · dΔθ _r / dt, is a term for outputting a current proportional to the differential value of the deviation, and is for compensating for a delay due to rotor inertia of the motor 34 and the like.

The third term, n _t ∫Δθ _r dt, is a term that outputs a current proportional to the integral value of the deviation, and is used to cancel a stationary deviation caused by an external force or friction.

The rear wheel turning angle output signal thus calculated is
It is output to the rear wheel steering device and controls the steering of the rear wheels as described above.

Next, the steering angle control of the front wheels performed by the controller P will be described in detail.

The front wheel turning angle target value _f is determined by the following equation (3).

_f = θ _s / r + ′ _f (3) where r is a steering wheel steering ratio, and ' _f is a front wheel correction steering wheel target value.

The front wheel correction steering angle target value ' _f is a rear wheel turning angle target value.
_The same value as _r is adopted. That is, the first term of the expression (3) indicates the front wheel turning angle given by the front wheel turning device, and the second term shows the front wheel turning angle given by the front wheel turning angle correction device. Becomes

Then, in the controller P, the front wheel steering angle target value
It compares the _f, and the front wheel turning angle signal theta _f sent from the front wheel turning angle sensor 32, and determines the front wheel turning output signal I _Mf.

The front wheel steering output signal I _Mf is given by the following equation (4).

_{I Mf = l f Δθ f +} m f · dΔθ f / dt + n f ∫Δθ f dt ... (4) _{where, l f, m f, n} f is a constant, [Delta] [theta] _f is the front wheel steering angle target value _r and the previous rotary which is the difference between the steering angle signal θ _r.

The first term l _f Δθ _f is a term that outputs a current proportional to the deviation. When the deviation between the target value and the actual steering angle is large, a large current proportional to the deviation is output. If they match, the current is zero.

The second term, m _f · dΔθ _f / dt, is a term that outputs a current proportional to the differential value of the deviation, and is used to compensate for a delay due to the rotor inertia of the motor.

The third term, n _f ∫Δθ _f dt, is a term that outputs a current proportional to the integral value of the deviation, and is used to cancel a stationary deviation caused by an external force or friction.

The front wheel turning output signal calculated in this way is output to the front wheel turning device, and controls the turning of the front wheels as described above.

Now, when the vehicle speed increases from a state of a steady circular turning at a constant speed, the rear wheel turning output signal I _Mr is output from the controller P
Output from When the signal I _Mr is output, control is performed such that the rear wheels are further steered in the direction in which the front wheels are currently steered. By turning the rear wheels, the steady side slip angle of the vehicle becomes zero.

At this time, a front wheel turning output signal I _Mf that corrects and turns the front wheels in the same direction by the angle of turning the rear wheels is output from the controller P to the front wheel turning angle correcting device. The front wheel turning angle correction device receives the signal I _Mf and _turns the front wheels.

In this manner, since the front wheels are corrected and steered, it is possible to prevent the turning radius from increasing due to the turning of the rear wheels.

Also, the controller P outputs the rear wheel turning output signal I _Mf also when the vehicle speed decreases from the state of the steady circular turning at a constant speed. However, at this time, control is performed so that the front wheels are steered in the direction opposite to the direction in which the front wheels are currently steered, from the current steering angle of the rear wheels.

By turning the rear wheels, the steady side slip angle of the vehicle becomes zero.

At this time, a front wheel turning output signal I _Mf that corrects and turns the rear wheels in the same direction as the rear wheels is output from the controller P to the front wheel turning angle correcting device by the angle of turning the rear wheels.

The front wheel turning correction device _turns the front wheels in response to the signal I _Mf .

As described above, since the front wheels are corrected and steered in the same direction as the steered angle of the rear wheels, a decrease in the turning radius caused by the steered angle of the rear wheels can be prevented.

As described above, in this embodiment, the vehicle sideslip angle is set to 0.
In addition, since the turning radius can be kept constant, the steering stability has been improved.

When the correction steering is performed in this manner, the universal joint 28 connecting the input shaft 1b and the pinion shaft 1c of the front wheel steering device is bent, and the handle 1 itself does not rotate or move. It does not give the above discomfort.

In this way, in fact, the influence of the rear wheel turning of the steering characteristic is kept constant by the correction turning of the front wheel, so the driver does not experience the turning of the rear wheel and the correction turning of the front wheel, so it is as if You can drive with the steering feel as if you are driving a 2WS car that does not steer wheels.

Next, another embodiment of the transmission mechanism of the present invention is shown in FIGS. In the embodiment shown in FIGS. 3 to 7, the configuration other than the transmission mechanism is the same as that of the first embodiment, and therefore, the details thereof are omitted.

The transmission mechanism of the second embodiment shown in FIG. 3 uses hypoid gears 44 and 45 instead of the worm 25 and the worm wheel 24 of the first embodiment.

In the second embodiment, the rotational force of the motor shaft 44 of the motor 34 is converted into the rotational movement of the hypoid gear 45 about the point A. The rotational movement of the hypoid gear 45
Is converted into the horizontal movement of the gear case 30 via the
And, by the horizontal movement of the gear case 30,
The pinion 21 pushes the rack 22 without lifting. Therefore, the fact that the rack 22 moves in the horizontal direction and the corrective steering is performed is the same as in the first embodiment.

The transmission mechanism of the third embodiment shown in FIG.
Instead of the worm wheel 24, single-row gears 46 and 47 are used.

In the third embodiment, the rotational force of the motor shaft 46 of the motor 34 is converted into the rotational movement of the single-row gear 47 about the point A. The rotational motion of the single-row gear 47 is converted into horizontal motion of the gear case 30 via the lever 23. The horizontal movement of the gear case 30 pushes the rack 22 without lifting the pinion 21. Because of this, the rack
22 is moved in the horizontal direction, and the correction steering is performed as in the first embodiment.

Next, in the fourth embodiment shown in FIG. 5, the worm wheel 49 meshing with the worm 48 is formed in a sector shape. The worm wheel 49 is configured to rotate around the line A. A lever 50 is connected to the worm wheel 49. The connection point between these two points is point A, which is the center of rotation of the worm wheel 49,
There are two points, point B offset from point A. As described above, the lever 50 connected to the worm wheel 49 is connected to the gear case 30 at the connection point C.

Now, when the motor shaft 34 of the motor 46 rotates, this rotational force is converted into a circular motion of the worm wheel 49 via the worm 48.

The circular motion of the worm wheel 49 is converted into a horizontal motion of the gear case 30 at the point C.

The horizontal movement of the gear case 30 pushes the rack 22 without lifting the pinion 21. For this reason,
The movement of the rack 22 in the horizontal direction and the correction steering is performed as in the first embodiment.

The fifth embodiment shown in FIG. 6 uses hypoid gears 51 and 52 instead of the worm 48 and the worm wheel 49 of the transmission mechanism shown in FIG.

In the sixth embodiment shown in FIG. 7, a single-row gear 5 is used instead of the worm 48 and the worm wheel 49 of the transmission mechanism shown in FIG.
3, 54 are used. Other configurations are the same as those of the mechanism shown in FIG.

In the third to seventh embodiments, the pinion shaft 1c
The hole portion of the gear case 30 into which is inserted constitutes the bearing of the present invention.

The front wheel turning angle correction device shown in FIG. 8 includes a bearing 29a in addition to the bearing 29 provided in the gear case 30 shown in FIGS.
The pinion shaft 1c is supported by the bearing 29 and the bearing 29a. Since the pinion shaft 1c is thus supported by the bearings 29 and 29a, the pinion shaft 1c
The rack 22 can be pushed horizontally to move it without the 1c being lifted off the rack 22.

As can be understood from these embodiments, any transmission mechanism may be employed as long as the pinion is not lifted from the rack.

In the vehicle of this embodiment, the front wheels are steered by the same angle in the same direction as the rear wheels in the vehicle that steers the rear wheels. However, the two wheels need not always be steered in the same direction.

[Brief description of the drawings]

FIGS. 1 and 2 show a first embodiment.
FIG. 2 is an overall view showing the configuration of each function, FIG. 2 is a partially enlarged view of the front wheel turning angle correction device, and FIGS. 3 to 7 are mechanical diagrams of the front wheel turning angle correction device of the second to sixth embodiments. FIG. 8 is a perspective view showing a front wheel steering angle correcting device according to a seventh embodiment, and FIG. 9 is a mechanism diagram showing a conventional front wheel steering mechanism. 1 ... handle, 1b ... input shaft, 1c ... pinion shaft, 2
... front wheel steering mechanism, 9 ... rear wheel steering mechanism, 26, 34 ... correction motor, 31 ... steering wheel rotation angle sensor, 32 ... front wheel steering angle sensor, 33 ... vehicle speed sensor, P ... controller

──────────────────────────────────────────────────続 き Continuation of the front page (56) References Japanese Utility Model Sho 61-88873 (JP, U) (58) Fields investigated (Int. Cl. ⁷ , DB name) B62D 5/22 B62D 6/00

Claims (1)

(57) [Claims] 1. A front wheel turning mechanism for turning a front wheel, a rear wheel turning mechanism for turning a rear wheel, a controller for controlling the front wheel turning mechanism and the rear wheel turning mechanism, and an operation angle of a steering wheel are detected. A steering wheel rotation angle sensor that outputs a steering wheel rotation angle signal, a vehicle speed sensor that detects a vehicle speed and outputs a vehicle speed signal, and a front wheel steering angle sensor that detects a front wheel steering angle and outputs a front wheel steering angle signal And a rear wheel steering angle sensor that detects a front wheel steering angle and outputs a rear wheel steering angle signal. A universal joint in which these two shafts are swingably connected, a correction motor, and a transmission mechanism for moving the pinion shaft parallel to the rack by rotation of the correction motor, and the controller outputs the output of the correction motor. System Then, in the turning angle correction device for correcting the front wheels to a desired turning angle, the controller determines a rear wheel turning angle target value based on the front wheel turning angle signal and the vehicle speed signal, and A rear wheel turning angle output signal is obtained from the target angle value and the rear wheel turning angle signal, and the rear wheel turning mechanism is controlled by the rear wheel turning angle output signal to correct the rear wheel turning angle. A front wheel turning angle target value is determined based on the rear wheel turning angle target value and the rear wheel turning angle signal, and a front wheel turning angle output signal is obtained from the front wheel turning angle target value and the front wheel turning angle signal. A steering angle correction device, wherein the front wheel steering mechanism is controlled by the front wheel steering angle output signal to correct the steering angle of the front wheels.