JPH0911928A - Steering device for vehicle capable of varying steering angle ratio - Google Patents

Abstract

PURPOSE: To prevent controllability of steering wheel at the time of motor fail from lowering. CONSTITUTION: To a steering main shaft 12 connected to a steering wheel 10 a gear case 18 of a speed reduction mechanism composed of a worm wheel 26 and a worm 44 are fixed. The wheel 26 is connected to an output shaft 24 connected to a shaft of a control valve through a joint or the like. In concomitant to the rotation of the wheel 10 a motor 70 is rotated to make a steering angle ratio varyable. With the arrangement by which the motor 70 is made unmovable when a reverse input is applied thereto, the similar function to the normal power steering without a steering device for a vehicle capable of varying the steering angle ratio is secured in case of motor fail.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vehicle steering angle ratio variable steering system capable of changing a ratio between an operation angle of a steering wheel and a turning angle of a steering wheel.

[0002]

2. Description of the Related Art Conventionally, there has been proposed a steering angle ratio variable steering device for a vehicle, which is used in a vehicle such as an automobile and can change a ratio between a steering operation angle and a steering wheel turning angle according to various conditions such as a vehicle speed. As an example, Japanese Patent Publication No. 3-44
It is possible to raise the vehicle steering angle ratio variable steering device shown in Japanese Patent Publication No. 030.

In this steering system with variable steering angle ratio, a planetary gear mechanism in which an input shaft is connected to a sun gear, an output shaft is connected to a planetary gear, and a variable steering angle motor is connected to a ring gear is provided between a steering shaft and a rack and pinion mechanism. It is interposed and is configured to change the steering angle ratio by changing the rotation speed of the ring gear.

[0004]

However, in this steering angle ratio varying device for a vehicle, when the rotation of the motor is stopped due to an abnormality in the motor, an abnormality in the electrical system, etc., and the ring gear is fixed, the steering wheel is operated. Since the rotation of the output shaft with respect to is reduced (because it is decelerated by the planetary gear mechanism),
There is a problem that operability is reduced.

In consideration of the above facts, the present invention takes into account the motor abnormality,
It is an object of the present invention to provide a vehicle steering angle ratio variable steering device in which the operability of a steering wheel is not deteriorated even when the rotation of a motor is stopped due to an abnormality in an electric system.

[0006]

According to a first aspect of the present invention, there is provided a variable steering angle ratio steering device for a vehicle, wherein an input shaft rotatably driven according to an operation of a steering wheel, an output shaft connected to a steering mechanism, A motor controlled based on a vehicle traveling state; and a reduction mechanism having a low reverse input efficiency that is coupled to the main body of the motor and reduces the rotation of the rotation shaft of the motor,
One of the input shaft and the output shaft is connected to at least one of the speed reduction mechanism and the main body, and the other is connected to the output shaft of the speed reduction mechanism. Reverse input efficiency = reducer input shaft torque / reducer output shaft torque.

According to a second aspect of the present invention, there is provided a variable steering angle ratio steering device for a vehicle, wherein a main body of an ultrasonic motor is provided on either one of a steering shaft connected to a steering wheel and an output shaft connected to steered wheels. The rotary shaft of the ultrasonic motor is connected to the other one.

[0008]

In the vehicle steering angle ratio variable steering device according to the first aspect, the operation of the steering wheel is transmitted to the output shaft of the steering mechanism via the input shaft and the output shaft of the speed reduction mechanism.

By rotating the rotating shaft of the motor along with the rotation of the steering wheel based on the running state of the vehicle, the rotating angle of the output shaft of the speed reducing mechanism with respect to the rotating angle of the input shaft can be changed, that is, the steering angle ratio can be changed. Therefore, the operability can be improved.

When the rotating shaft of the motor is not rotated, the input shaft and the output shaft connected to the steering mechanism are directly connected to each other, and normal steering operation can be performed.

The deceleration mechanism is provided so as to decelerate the rotation of the rotary shaft of the motor and has a low reverse input efficiency.
It is possible to fix the operation of the reduction gear when the electric current stops flowing to the motor (the idling of the rotating shaft of the motor due to the operation of the steering wheel can be prevented).
Therefore, the operation of the steering wheel is not slowed down,
It is possible to perform an operation similar to that of a normal steering system that is not provided with a vehicle steering angle ratio variable steering device, and operability does not deteriorate when the motor fails.

In the vehicle steering angle ratio variable steering device according to the second aspect of the invention, the operation of the steering wheel is transmitted to the output shaft connected to the steering mechanism via the ultrasonic motor.

By rotating the rotary shaft of the ultrasonic motor together with the rotation of the steering wheel based on the running state of the vehicle, the rotation angle of the output shaft with respect to the rotation angle of the input shaft can be changed, that is, the steering angle ratio can be changed. So
Operability can be improved.

When no current is applied to the ultrasonic motor, or when no current is applied to the ultrasonic motor, the rotor and stator of the ultrasonic motor are rigidly connected by friction, so that the input shaft and the output shaft connected to the steering mechanism are directly connected. Therefore, normal steering operation can be performed. Moreover, since the ultrasonic motor is simply interposed between the steering shaft and the output shaft,
Steering control can be performed with a simple configuration.

[0015]

【Example】

[First Embodiment] A first embodiment of the present invention will be described with reference to FIGS.

As shown in FIG. 1, a flange 14 is integrally formed on a steering main shaft 12 as an input shaft connected to a steering wheel 10. The flange 14 is fixed to the gear case 18 of the vehicle steering angle ratio variable steering device 16 with a bolt 20.

In the gear case 18, a large-diameter hole 22 is formed coaxially with the steering main shaft 12 on the side opposite to the side where the flange 14 is fixed.

Inside the gear case 18, a worm wheel 26 attached to the output shaft 24 is inserted from the hole 22 and arranged. The worm wheel 26
Is fixed to the output shaft 24 by a key 28.

Further, inside the gear case 18, a ball bearing 28 is mounted coaxially with the steering main shaft 12 on the side where the flange 14 is fixed.

An output shaft cover 30 is fixed to the gear case 18 by bolts 32 on the side surface where the hole 22 is formed. A round hole 34 is formed in the center of the output shaft cover 30, and the output shaft 24 projects from the round hole 34.

An oil seal 36 and a ball bearing 38 for preventing oil leakage from the shaft portion are attached to the output shaft cover 30, and the output shaft 24 has a ball bearing 38 of the output shaft cover 30 and the inside of the gear case 18. It is rotatably supported by a ball bearing 28. The output shaft cover 30
An O-ring 40 that prevents oil leakage is sandwiched between the gear case 18 and the gear case 18.

A worm 44 integrated with a shaft 42 meshes with the worm wheel 26. The worm wheel 26 and the worm 44 form a reduction mechanism.

A shaft cover 46 is fixed to the gear case 18 by a bolt 48 on a side surface (not shown) on the arrow A direction side. A recess 50 is formed in the central portion of the shaft cover 46, and the shim plate 52 and the ball bearing 54 are provided in the recess 50.
Is attached. A packing 56 for preventing oil leakage is provided between the shaft cover 46 and the gear case 18.
Is pinched.

A cylindrical motor flange 60 is attached to the side surface of the gear case 18 on the arrow B direction side through a packing 58 with bolts 62.

The motor flange 60 has a shim plate 64,
An oil seal 66 and a ball bearing 68 are attached to prevent oil from leaking from the shaft portion.

The shaft 42 integrated with the worm 44 is rotatably supported by a ball bearing 54 of a shaft cover 46 and a ball bearing 68 of a motor flange 60.

A motor 70 is fixed to the motor flange 60 with bolts 72. The rotating shaft 73 of the motor 70 is connected to the shaft 42 via a coupling 74.

The cable 7 connected to the motor 70
Reference numeral 6 is connected to a motor drive driver 82 via a flat wire 78 and a cable 80 that are gently wound in a spiral shape on the steering main shaft 12.

The motor driving driver 82 is connected to the vehicle-mounted computer 84. The vehicle-mounted computer 84 includes a vehicle speed sensor 86, a steering angle sensor 88 for detecting a rotation angle of a wheel attached to the steering main shaft 12, and a rack stroke sensor 90 described later.
(See FIG. 2), various sensors such as a yaw rate (yaw angular velocity) sensor 92 are connected to the vehicle-mounted computer 8
4 controls the motor 70 based on the vehicle information.

As shown in FIG. 2, the output shaft 24 of the vehicle steering angle ratio variable steering device 16 includes a joint 94 and a shaft 9.
6. A shaft (not shown) of a control valve 102 that is integrally attached to a power cylinder 100 of a power steering (a rack and pinion type power steering in this embodiment) is connected via a joint 98.

A rack stroke sensor 90 for detecting the amount of movement of the rack bar 101 is attached to the rack bar 101 of the power cylinder 100. In addition,
The power cylinder 100, the control valve 102, the rack bar 101, etc. correspond to the steering mechanism of the present invention.

The worm 44 and the worm wheel 26
The reverse input efficiency of the reduction mechanism configured by means of the torque from the output shaft 24 or the torque from the steering main shaft 12 depends on the worm 44 and the worm wheel 2.
It is set to zero so that the relative speed of 6 does not occur, that is, the rotation shaft 73 of the motor 70 does not rotate.

Next, the operation of this embodiment will be described. When the steering wheel 10 is rotated while the motor 70 is stopped, relative rotation does not occur between the steering main shaft 12 and the output shaft 24. That is, the steering main shaft 12 and the output shaft 24 are directly connected.

On the other hand, the motor 70 is arranged so that the output shaft 24 rotates in the same direction as the rotation direction of the steering main shaft 12 as the steering main shaft 12 rotates.
As a result, the turning angle of the output shaft 24 becomes larger than the turning angle of the steering main shaft 12. Further, when the motor 70 is rotated so that the output shaft 24 rotates in the direction opposite to the rotation direction of the steering main shaft 12 with the rotation of the steering main shaft 12, as a result, the cutting angle is smaller than the cutting angle of the steering main shaft 12. The corner becomes smaller. That is, in this embodiment, as the steering main shaft 12 rotates,
The steering angle ratio can be changed by rotating the motor 70.

The on-vehicle computer 84 uses the steering angle sensor 88 and the rack stroke sensor 90 to detect the rotational position of the steering main shaft 12 and the rack bar 1.
The position of 01 is monitored, and when the steering wheel 10 is in the neutral position, the motor 70 is controlled so that the rack bar 101 is in the neutral position. Further, the system failure can be determined based on the difference between the information on the rotational position of the steering main shaft 12 by the steering angle sensor 88 and the information on the position of the rack bar 101 by the rack stroke sensor 90.

The vehicle steering angle ratio variable steering device 16 of the present embodiment
Then, depending on the control method, a vehicle speed variable gear ratio steering system that changes the steering angle ratio according to the vehicle speed, a steering angle variable gear ratio system that changes the steering angle ratio according to the turning angle of the steering wheel 10, and automatic driving, etc. Can be applied to.

In order to make the vehicle speed variable gear ratio steering system, the vehicle-mounted computer 84 controls the motor 70 by performing calculation based on information from various sensors such as the vehicle speed sensor 86, the steering angle sensor 88, and the rack stroke sensor 90. .

For example, when the vehicle is running at a low speed, the turning angle of the output shaft 24 relative to the turning angle of the steering wheel 10 is set to be large. In this case, since the change in the direction of the steered wheels with respect to the steering operation becomes large,
The steering operation amount is small when entering the garage,
It is easy to put in a garage.

On the other hand, when the vehicle is running at high speed,
Output shaft 2 for the rotational speed (or turning angle) of the steering wheel 10 (steering main shaft 12)
Set the rotation speed (or cutting angle) of 4 to a small value. This makes it possible to increase high-speed stability.

The vehicle speed, the rotational speed of the output shaft 24, and the steering main shaft 1 for performing the control as described above.
FIG. 3 shows an example of the relationship between the two rotation speeds.

Further, in order to make the steering angle variable gear ratio system, the relationship between the rotation angle of the steering wheel 10 and the rotation angle ratio (the rotation angle of the steering wheel 10 / the rotation angle of the steered wheels) is shown in FIG. To set.

As a result, the gear ratio is large in the small rudder angle range, and the gear ratio is small when the rudder is steeply turned, so that the operability in both the small rudder angle range and the large rudder angle range can be made compatible. it can.

When used for automatic driving, the steering wheel 10 and the steering main shaft 1
2 or the gear case 18 is fixed to a vehicle body (not shown) by a lock mechanism so that the motor 7 cannot rotate.
The output shaft 24 may be rotated only by 0 rotation.

In order to enable automatic driving of the vehicle, for example, the vehicle-mounted computer 84 is provided with a sensor (radar, TV camera, etc.) for detecting the front vehicle, a sensor (TV camera for recognizing the white line of the road) for detecting the road. , A magnetic sensor for detecting a magnetic marker embedded in the road, etc. is connected, and the on-vehicle computer 84 performs calculation based on the information of each sensor to rotate the motor 70, open the accelerator, brake, and Control position etc.

The variable vehicle speed gear ratio steering system and the variable steering angle gear ratio system may be combined, whereby a steering system with less discomfort can be obtained.

Furthermore, it is also possible to switch between the combination of the variable vehicle speed variable gear ratio steering system and the variable steering angle gear ratio system and the automatic operation, which facilitates the steering and the high speed operation of the variable vehicle speed gear ratio steering system. It is possible to achieve both a system that can reduce the driving load on the driver by automatic driving on the road.

The steering angle ratio may be changed by judging not only the vehicle speed but also the yaw rate, the acceleration / deceleration, the lateral G, the position of the shift lever, etc., or by the switch operation of the driver. good.

Variable steering angle ratio steering device 16 for vehicle of the present embodiment
According to the above, the following effects can be obtained. (1) Since it is provided between the steering wheel 10 and the control valve 102 of the power steering, the power cylinder 100 of the power steering,
As the control valve 102 and the like, conventional products can be used as they are, and there is no need to modify the power steering system. (2) Road reaction force is also controlled by the vehicle steering angle ratio variable steering device 16
The steering wheel 10 can receive a reaction force equivalent to that of a conventional power steering without
It is possible to reduce discomfort during steering. (3) Since the motor 70 is between the steering wheel 10 and the power steering control valve 102, the output of the motor 70 can be small, and a small one can be used. (If a motor is provided on the output side of the power steering to drive the motor, a large torque is required and the motor becomes large.) (4) The strength is such that the worm 44,
It is sufficient to secure the strength of the worm wheel 26 and the bearings (ball bearings), and the motor 70 itself may rotate the worm wheel 26 with almost no strength required. (5) Since the motor 70 does not rotate due to reverse input, during motor failure {when locked (for example, bearing part is stuck) or unlocked (when holding force is lost in the non-energized state)}, It functions exactly like a normal power steering without the vehicle steering angle ratio variable steering device 16. (6) The system can be constructed at a lower cost under the present circumstances because the configuration can be made by combining relatively easily available elements such as a normal motor and a worm & worm wheel. [Second Embodiment] A second embodiment of the present invention will be described with reference to FIG. The same components as those in the first embodiment are denoted by the same reference numerals, and description thereof will be omitted.

The vehicle steering angle ratio variable steering device 16 of the present embodiment
Includes a housing 116 in which a large-diameter disk 110 and a small-diameter disk 112 are connected by three legs 114.

The steering main shaft 12 is coaxially fixed to the center of the small-diameter disk 112.

A worm wheel 26 is arranged between the large-diameter disk 110 and the small-diameter disk 112, and the output shaft 24 is a ball bearing 11 mounted on the large-diameter disk 110.
8 is rotatably supported.

A worm 44 meshes with the worm wheel 26, and the worm 44 is rotated by a motor 70 attached to a large-diameter disk 110.

Variable steering angle ratio steering device 16 for a vehicle of this embodiment
The operation principle and effect of are the same as those of the first embodiment.

If the motor 70 is arranged as a brushless motor coaxially with the housing 116 and a gear transmission mechanism combining a bevel gear and the like is provided between the worm 44 and the motor 70, the diameter of the housing 116 becomes small.
It is also possible to make the steering angle ratio variable steering device 16 for a vehicle compact. [Third Embodiment] A third embodiment of the present invention will be described with reference to FIG. The same components as those in the first embodiment are denoted by the same reference numerals, and description thereof will be omitted.

Variable steering angle ratio steering device 16 for vehicle of this embodiment
Includes a planetary gear mechanism 121 as a speed reduction mechanism.

In this embodiment, the case 70A of the motor 70 is used.
The steering main shaft 12 has a flange 14 coaxially attached thereto.

An annular flange 120 is attached to the case 70A of the motor 70 with a bolt (not shown), and a ring gear 122 is attached to the flange 120 with a bolt 124.

On the other hand, a carrier 126 is attached to the output shaft 24, and a planetary gear 128 which meshes with the ring gear 122 is attached to the carrier 126. The rotary shaft (not shown) of the motor 70 is
A sun gear 130 that meshes with the planetary gear 128 is attached.

Also in this embodiment, when the steering wheel 10 is rotated while the rotating shaft of the motor 70 is stopped, relative rotation does not occur between the steering main shaft 12 and the output shaft 24. That is, the steering main shaft 12 and the output shaft 24 are directly connected. Further, if the motor 70 is operated in the same manner as in the above-described embodiment in accordance with the rotation of the steering main shaft 12, the steering angle ratio can be similarly changed.

The planetary gear mechanism 121 sets the reverse input efficiency to zero so that the motor 7 is operated when the steering wheel 10 is operated even when the motor 70 is in the non-energized state.
It is possible to maintain the function as a normal steering without causing 0 to idle.

As the vehicle steering angle ratio variable steering device 16, instead of the planetary gear mechanism 121, for example, a reduction mechanism having a large reduction ratio, such as a harmonic drive, a cycloidal gear harmonic reducer, or a circulator gear harmonic reducer. Can be used. Even in these cases, the reduction ratio and the like are determined so that the reverse input efficiency becomes zero.

In these cases, as shown in FIG. 7, the main body 123A of the reduction gear 123 is coaxially connected to the case 70A of the motor 70, and the input shaft (not shown) of the reduction gear 123 is connected to the rotation shaft of the motor 70. (Not shown), the reduction gear 123
It suffices to connect the output shaft 123B of the above to the output shaft 24. [Fourth Embodiment] A fourth embodiment of the present invention will be described with reference to FIG. The same components as those in the first embodiment are denoted by the same reference numerals, and description thereof will be omitted.

The vehicle steering angle ratio variable steering device 16 of the present embodiment
The ultrasonic motor 140 is used for the.

In this embodiment, the flange 14 of the steering main shaft 12 is the case 1 of the ultrasonic motor 140.
It is attached coaxially to 42.

Further, the output shaft 24 is a rotary shaft (not shown) of the ultrasonic motor 140 via a coupling (not shown).
It is connected to.

In the present embodiment, during normal steering, the rotor and the stator of the ultrasonic motor 140 are rigidly connected by friction by cutting off the power supply to the ultrasonic motor 140, so that the steering main shaft 12 and the output shaft are not connected. It is directly connected to 24 and functions as a normal steering wheel. In this case, as a matter of course, the holding torque of the ultrasonic motor 140 is set larger than the torque input from the steering wheel 10 in view of the safety factor. A speed reducer may be inserted between the rotary shaft of the ultrasonic motor 140 and the output shaft 24.

On the other hand, along with the rotation of the steering main shaft 12, based on information from various sensors such as a vehicle speed sensor 86, a steering angle sensor 88, a rack stroke sensor 90, and in some cases, a vehicle state such as a yaw rate and a lateral G. If the ultrasonic motor 140 is operated by the command value calculated by the vehicle-mounted computer 84, it is possible to change the steering angle ratio by performing auxiliary steering that supplements the steering operation of the driver and addition and return operations by a certain ratio. It will be possible.

In the above-described embodiment, the flat wire 78 is gently spirally wound around the steering main shaft 12 to energize the motors 70 and 140. However, as shown in FIG. The carbon brush 15 attached to the cable 80 by attaching the conductive ring 150 via the insulator 152
4 may be energized by contacting the ring 150 with the spring 156.

Further, when a speed reducer is used for the vehicle steering angle ratio variable steering device 16, it is preferable to use a speed reducer having a high positive input efficiency (= reducer output shaft torque / reducer input shaft torque). Input efficiency (= reducer input shaft torque /
It is necessary to use one in which the reduction gear output shaft torque) becomes zero with respect to the required reverse torque (manual steering torque input to the power steering). what if,
If the reverse input efficiency does not reach zero, a separate brake or lock mechanism is required.

The reduction ratio (reduction gear output shaft rotation speed / reduction gear input shaft rotation speed) is normally 1 / several 10 to 1 / several 1 when a general motor such as a DC motor or a synchronous motor is used.
It is about 00 and is selected in consideration of the forward input efficiency and the reverse input efficiency.

When a reduction gear and an ultrasonic motor are used, the reduction ratio is 1 because the ultrasonic motor has a low rotation speed.
/ 1 to 1/10 is selected, and it is difficult to expect self-locking by the speed reducer, so the self-locking function of the ultrasonic motor itself is used. In this case, by using the speed reducer, the frictional force (self-lock torque) of the ultrasonic motor itself can be increased by the speed reduction ratio and used.

[0072]

As described above, the variable steering angle ratio steering device for a vehicle according to claim 1 has the above-mentioned structure, and therefore, even if the motor stops rotating due to an abnormality in the motor, an abnormality in the electrical system, or the like. The steering wheel can be operated in the same manner as the conventional one, and the operability of the steering wheel is not deteriorated.

In the vehicle steering angle ratio variable steering device according to a second aspect of the invention, an ultrasonic motor is interposed in a steering system that connects an input shaft connected to the steering wheel and an output shaft connected to the steered wheels. Therefore, even if the rotation of the motor is stopped due to the abnormality of the motor, the abnormality of the electric system, or the like, the steering operation similar to the conventional one can be performed, and the operability of the steering wheel is not deteriorated. Further, in order to change the steering angle ratio, it is only necessary to interpose the ultrasonic motor in the steering system that connects the input shaft connected to the steering wheel and the output shaft connected to the steering wheel, and the configuration is extremely simple. The size of the device can be reduced, and the degree of freedom in design is high.

[Brief description of the drawings]

FIG. 1 is an exploded perspective view of a main portion of a steering system to which a vehicle steering angle ratio variable steering device according to a first embodiment of the present invention is applied.

FIG. 2 is a perspective view of a steering system to which the vehicle steering angle ratio variable steering device according to the first embodiment of the present invention is applied.

FIG. 3 is a graph showing a relationship among a steering main shaft rotation speed, an output shaft rotation speed, and a vehicle speed when a vehicle speed variable gear ratio steering system is used.

FIG. 4 is a graph showing a relationship between a steering wheel rotation angle and a rotation angle ratio when a steering angle variable gear ratio system is used.

FIG. 5 is a perspective view of a steering system to which a vehicle steering angle ratio variable steering system according to a second embodiment of the present invention is applied.

FIG. 6 is a perspective view of a steering system to which a vehicle steering angle ratio variable steering device according to a third embodiment of the present invention is applied.

FIG. 7 is a perspective view of a steering system to which a vehicle steering angle ratio variable steering device according to a modification of the third embodiment is applied.

FIG. 8 is a perspective view of a steering system to which a vehicle steering angle ratio variable steering system according to a fourth embodiment of the present invention is applied.

FIG. 9 is a perspective view of a power feeding means showing another method of energizing the motor.

[Explanation of symbols]

 16 Vehicle Steering Ratio Variable Steering Device 10 Steering Wheel 12 Steering Main Shaft (Input Shaft) 24 Output Shaft 26 Worm Wheel (Reduction Mechanism) 44 Worm (Reduction Mechanism) 70 Motor 100 Power Cylinder (Steering Mechanism) 101 Rack Bar (Steering) Mechanism) 102 Control valve (steering mechanism) 121 Planetary gear mechanism (reduction mechanism) 140 Ultrasonic motor

Claims (2)

[Claims] 1. An input shaft that is rotationally driven according to an operation of a steering wheel, an output shaft that is connected to a steering mechanism, a motor that is controlled based on a vehicle traveling state, and a motor that is connected to a main body of the motor. A reduction mechanism having a low reverse input efficiency for decelerating the rotation of the rotation shaft of the motor, wherein one of the input shaft and the output shaft is at least one of the reduction mechanism and the main body, and the other is the reduction speed. A variable steering angle ratio steering device for a vehicle, characterized in that the steering device is connected to an output shaft of a mechanism. 2. A body of an ultrasonic motor is connected to either one of a steering shaft connected to a steering wheel and an output shaft connected to a steering wheel, and a rotating shaft of the ultrasonic motor is connected to the other. A characteristic steering angle variable steering device for a vehicle.