JPS6231560A - Steering device for car - Google Patents

Abstract

PURPOSE:To suppress a reaction force at the time of steering a wheel to be small and reduce a load torque applied to an actuator for controlling a transmission ratio variable mechanism by providing a power steering mechanism in between said transmission ratio variable mechanism and a tie rod. CONSTITUTION:A transmission ratio variable mechanism 9 for varying a transmission ratio R of a wheel steering angle thetaW to a handle steering angle thetaH, is provided midway in a steering force transmitting route between a handle 1 and a steering gear device 3. A power steering mechanism 7 for assisting transmission force from the handle 1 to wheels 8, is installed in the steering gear device 3, and the rack of the gear device 3 is connected to each of the wheels 8 via tie rods 6 and knuckle arms. Thereby, a reaction force generated at the time of steering wheels 8 can be suppressed to be made small by the action of the steering assisting force of the power steering mechanism 7, reducing load applied to a stepping motor 20.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a steering device that can change the transmission ratio (reduction ratio) of a wheel steering angle to a steering wheel steering angle of an automobile.

(Prior Art) In general, a steering device for an automobile converts the rotational movement of a steering wheel into a lateral displacement movement of a tie rod through a steering gear device such as a rack-and-binion. It changes the direction of the left and right steering wheels, but the amount of rotation of the steering wheel (handle steering angle) and the turning angle of the wheels (
(wheel steering angle) is normally always maintained in a constant correspondence relationship. However, for example, when a car is running at high speed, it is desirable to increase the transmission ratio of the wheel steering angle to the above-mentioned steering wheel steering angle and to reduce the size of the wheel steering angle with respect to a constant steering wheel steering angle, in order to ensure driving stability. When driving at low speeds, the above transmission ratio is conversely reduced and the wheel rudder is adjusted to a constant steering angle in order to make the car's behavior more agile and provide a good driving feeling, or to make it easier to park the car in the garage. It is desirable to increase the angle.

Therefore, in order to meet such requirements, as disclosed in Japanese Patent Application Laid-open No. 58-224852, for example,
A speed-sensitive steering device has been proposed that changes the transmission ratio of the wheel steering angle to the steering wheel steering angle in accordance with the vehicle speed of the automobile. A transmission mechanism is installed between the steering handle and the steering column, consisting of a pair of opposing variable bidge pulleys and a V-belt wrapped between both pulleys. It is controlled by a stepping motor so that it becomes larger as it rises. According to this, the rotation transmission ratio from the steering wheel to the steering column increases when the vehicle speed is high, and as a result, the turning angle of the wheels relative to a constant steering wheel steering angle becomes small at high speeds and large at low speeds, and as the vehicle speed increases. Corresponding good steering characteristics can be obtained.

(Problems to be Solved by the Invention) However, in a steering device equipped with such a variable transmission ratio mechanism, the operation of the variable transmission ratio mechanism is controlled by an actuator such as a stepping motor. The load torque applied to the actuator increases due to the reaction force during wheel steering.

The present invention has been made in view of the above, and an object of the present invention is to provide means for assisting the steering force at a specific location in the steering force transmission path, thereby improving the control of the variable transmission ratio mechanism. The purpose is to reduce the load torque applied to the actuator.

(Means for Solving the Problems) In order to achieve the above object, the solving means of the present invention is provided in the steering force transmission path between the steering handle and the tie rod, and is configured to adjust the wheel steering angle relative to the steering wheel steering angle. A variable transmission ratio mechanism that changes the transmission ratio, a driving state detection means that detects the driving state such as the vehicle speed of the automobile, a controller that receives a signal from the detection means and outputs a control signal, and a control signal from the controller. The subject matter is a steering device for an automobile equipped with an actuator such as a stepping motor that controls the operation of the variable transmission ratio mechanism based on the above, and a power steering mechanism is provided between the variable transmission ratio mechanism and the tie rod. That is.

(Function) Therefore, with the above configuration, in the present invention, when the steering wheel is steered to turn the wheels, the driving state detecting means detects the driving state of the vehicle at that time.
til from the controller that receives the output of this detection means
The actuator is operated based on the l II signal, and the variable transmission ratio mechanism is controlled by the operation of the actuator, and the transmission ratio of the wheel steering angle to the steering wheel steering angle is variably controlled.

In that case, the power steering mechanism provided between the variable transmission ratio mechanism and the tie rod operates to assist the steering force, so the action of this assist h suppresses the reaction force when turning the wheels. This reduces the load torque applied to the actuator for controlling the variable transmission ratio mechanism.

(Example) Embodiments of the present invention will be described below based on the drawings.

FIG. 1 shows the overall configuration of a steering device for an automobile according to an embodiment of the present invention, in which 1 is a steering handle, and 3 is a rack and pinion type that converts the rotational motion of the steering handle 1 into the steering motion of wheels 8 and 8. As shown in enlarged detail in FIG. 2, the steering gear device 3 includes a pinion 3b in a steering gear box 3a, and a rack 3C extending in the width direction of the vehicle body and meshing with the pinion 3b. The pinion 3b is connected to the handle 1 via the first and second intermediate shafts 4, 5 and the handle shaft 2, while the rack 3C is connected to the handle 1 via each tie rod 6 and a knuckle arm (not shown). and is connected to each wheel 8.

The steering gear device 3 includes a handle 1 to wheels 8.
, 8 is equipped with a power steering mechanism 7 as a feature of the present invention for assisting the steering force transmitted to the steering wheels. , the power steering mechanism 7 is connected to the rack 3C.
A piston 7C is interposed between the rack 3C and the tie rod 6 on one side (the left side in the figure) and is connected to the rack 3C and the tie rod 6.
A hydraulic power cylinder 7a having cylinder chambers 7d and 7c defined therein and a hydraulic power cylinder 7a connected to the steering gear V box 3a, which supplies the power from a hydraulic pump (not shown) in response to the steering of the handle 1, is connected to the steering gear V box 3a. cylinder 7
It is equipped with a rotary control valve 7b that switches the supply direction of the pressure oil supplied to each cylinder chamber 7d, 7e of a and controls the pressure, and the pressure oil from the hydraulic pump is input to the steering wheel 1. Accordingly, the power is supplied to the power cylinder 7a while being controlled by the control valve 7b, and the output of the power cylinder 7a assists the steering force to steer the wheels 8.8. Note that 7f is a pressing member that presses the rank 3C against the pinion 3b, and 7a and 70 are rack sealing materials.

Further, a variable transmission ratio mechanism 9 is provided in the middle of the steering force transmission path between the steering wheel 1 and the steering gear device 3 to change the transmission ratio R from the steering wheel angle θH to the wheel steering angle θW. As shown in enlarged detail in FIGS. 3 to 5, the variable transmission ratio mechanism 9 includes a planetary south center type differential gear mechanism 13 in a housing 10, and the differential tooth width mechanism 13 is attached to the housing 10. the intermediate shaft 4 facing inside the 10;
It is provided between an input shaft 12 which is disposed facing the intermediate shaft 4 on the same axis and is drivingly connected to the handle shaft 2 at the end opposite to the intermediate shaft 4. The differential gear mechanism 13 includes a sun gear 14 as an input gear element fixed to an input shaft 12 connected to the handle 1 side, and an output fixed to an intermediate shaft 4 connected to the wheels 8, 8 side. Ring gear 15 as a gear element and both gears 14.15
Three planetary pinions 16.16. as reaction gear elements are interposed at equal angular intervals so as to mesh with both gears 14.15. ..., and the binion 16.16. . . . is a pinion shaft 17, 1 attached to a pinion carrier 18 rotatably fitted externally on the input shaft 12.
7. It is carried through... Further, a worm wheel 19 is formed on the outer periphery of the binion carrier 18, and a worm 21 fixed to the rotating shaft 11 is engaged with the worm wheel 19, and the rotating shaft 11 is connected to the rotating output shaft 20a of the stepping motor 20. connected. Therefore, the rotation of the stepping motor 20 controls the operation of the differential tooth width mechanism 13 via the worm 21 and the worm wheel 19, and the rotation of the nion carrier 18 around the input shaft 12 causes the rotation of the planetary carrier 18. The binions 16°16, . . . are transferred between the sun gear 14 and the ring gear 15, and the binions 16.
16. ... is configured to change the transmission ratio R of the wheel steering angle θW to the steering wheel steering angle θH by controlling the amount of rotation from the handle shaft 2 or sun gear 14 to the ring gear 15 and the intermediate shaft 4 by increasing or decreasing the rolling of the steering wheel. has been done.

On the other hand, 4o is a controller consisting of a computer that outputs a control signal to the stepping motor 20 that controls the operation of the variable transmission ratio mechanism 9, and controls the controller 1-roller 40. Output signals from a steering wheel angle sensor 41 consisting of an encoder that detects the steering wheel angle θH and a vehicle speed sensor 42 that detects the vehicle speed V of the automobile are input. The steering wheel angle sensor 41 is connected to the housing 1 as shown in FIG.
0, and its rotating shaft 41a is connected to the input shaft 1.
In contrast to 2, the drive gear 22 fixed to the input shaft 12 and the driven gear 23 meshing with the drive gear 22 are connected to drive the vehicle, and these sensors 41 and 42 detect the driving state of the vehicle. The means are constituted.

As shown in detail in FIG. 7, the controller 40 controls the steering wheel angle sensor 41 and the vehicle speed sensor 4.
The steering wheel steering angle θH and the vehicle speed ■ detected by 2 are compared with a characteristic map set in advance and stored in the characteristic storage section 43, and the target transmission ratio R to be controlled by the variable transmission ratio mechanism 9 is calculated. and a target transmission ratio calculation section 44 that calculates the stepping motor 2 based on the output signal of the calculation section 44.
0 so as to match the rotation angle corresponding to the calculated target transmission ratio R.

The above characteristic map is set such that the transmission ratio R of the wheel steering angle θW to the steering wheel steering angle θH increases as the vehicle speed V increases.

Note that each planetary pinion 16 in the differential gear mechanism 13 has split gears 16a, 1 in the axial direction of the pinion shaft 17.
6a, and each divided gear 16a is rotatably supported by a pinion shaft 17. Further, the ends of a ring-shaped torsion spring 16b arranged around the pinion shaft 17 are engaged with the split gears 16a, 16a, respectively, and the torsional force of the torsion spring 16b causes the split gears 15a, 16a to are relatively urged to rotate in opposite directions.

Further, as shown in FIGS. 3 and 6, a predetermined response force (reaction force) to the steering of the steering wheel 1 is applied to the steering force transmission path between the variable transmission ratio mechanism 9 and the steering wheel 1. A feedback device 24 is provided. The nuclear response device [24 is a spring shaft 2 disposed parallel to the input 111d112 and rotatably supported by the housing 10.
5, and a driven gear 26 that meshes with the driving gear 22 on the input shaft 12 is integrally fixed to the spring shaft 25,
The diameter of the driven gear 26 is the same as that of the drive gear 22 on the input shaft 12 side.
The gears 22 and 26 constitute a deceleration mechanism 27, and the deceleration mechanism 27 decelerates the rotation of the input shaft 12 as the steering wheel 1 is steered.
When the steering wheel 1 is steered from the neutral position to the maximum steering angle position, the spring shaft 25 rotates approximately one rotation (that is, the rotation angle is approximately 3600 degrees). A pair of cylindrical spring mounting members 28, 28 are externally fitted concentrically and rotatably around the spring shaft 25, and a spring is attached to the opposite side of each spring mounting member 28 from its inner circumference. An engagement piece 29 protruding toward the shaft 25 is attached with a bolt 30. Further, a locking key 32 that can be engaged with both of the engaging pieces 29 and 29 is fixed to the spring shaft 25 by a bolt 31, and by the engagement of this locking key 32 and each of the engaging pieces 29, each spring is attached. The member 28 rotates integrally with the spring shaft 25. In addition, each of the spring mounting members 28 and 28 has a spring mounting member 2.
8. A spiral spring 33 wound in opposite directions around 28.
The inner end of each spiral spring 33 is locked, and the outer end of each spiral spring 33 is fixed to the housing 10 with a bolt 34. The spring force of each spiral spring 33 rotates the corresponding spring mounting member 28. It is designed to energize. Furthermore, abutment 35 is fixed to the outer periphery of each spring mounting member 28 at a portion substantially corresponding to the engagement piece 29 with a bolt 36. In addition, a stopper member 37 made of a bolt member that comes into contact with the abutment 35 to stop the rotation of each spring mounting member 28 is supported through the housing 10.
When each stopper member 37 is in contact with the corresponding stopper 36, each spiral spring 33 is not released and the spring force remains, and the residual spring force of both spiral springs 33, 33 is applied to the spring axis. 25 so that they are antagonistic and cancel each other out.

When the spring shaft 25 rotates in one direction with the steering of the handle 1, the locking key 32 on the outer periphery of the spring shaft 25 and the engagement piece 29 on the inner periphery of each spring mounting member 28 engage with each other.
The spring mounting member 28 rotates integrally with the spring shaft 25 to contract the corresponding spiral spring 34 in the direction of the small diameter, and the spring 33
The restoring force is configured to provide resistance to the rotation of the spring shaft 25 and provide a responsive force to the steering of the handle 1.

Therefore, in the above embodiment, while the car is running,
When the steering wheel 1 is turned, the movement is transmitted to the input shaft 12 of the variable transmission ratio mechanism 9 via the steering wheel shaft 2.
The transmission is transmitted to rotate the rotation gear r14 of the differential gear mechanism 13. Further, the steering wheel steering angle θH that changes with the steering of the steering wheel 1 is detected by the steering wheel steering angle sensor 41, and the vehicle speed V at that time is detected by the vehicle speed sensor 42, and the output signals of both sensors 41 and 42 are detected. A control signal is output from the controller 40 that receives the signal to the stepping motor 20 that controls the operation of the differential gear mechanism 13, and the rotation of the motor 20 is controlled. The pinion carrier 18 is rotationally driven. That is, in the differential tooth 11 mechanism 13, the sun gear 14 rotates by an angle proportional to the steering angle θH of the handle 1, and at the same time, the binion carrier 18 rotates according to the rotation angle of the stepping motor 20 controlled by the controller 40. will be done. Therefore, the ring gear 15 of the differential gear mechanism 13 and the intermediate shaft 4 integrated therewith rotate by an angle that increases or decreases the rotation angle of the binion carrier 18 with respect to the steering angle θH, and the rotation of the intermediate shaft 4 As a result, the wheels 8.degree. 8 are steered, thereby variably controlling the transmission ratio R of the wheel steering angle .theta.W to the steering wheel steering angle .theta.H.

Furthermore, as the intermediate shaft 4.5 rotates in conjunction with the steering of the steering wheel 1, the power steering mechanism 7 of the steering gear device 3 is operated to assist the steering force from the steering wheel 1 to the wheels 8, 8.

In that case, since the power steering mechanism 7 is disposed between the variable transmission ratio mechanism 7 and the tie rod 6, when the wheels 8.8 are steered by the action of the steering angle 1 to force of the power steering mechanism 7, The generated reaction force is kept small, and the load torque applied to the stepping motor 20 can be significantly reduced by the reaction force.

Further, a worm 21 is attached to the rotating shaft 11 that is integrally connected to the output shaft 2Qa of the stepping motor 20, and one worm wheel that meshes with the worm 21 is formed on the binion carrier 18 of the differential gear mechanism 13. Therefore, the rotation of the output shaft 20a of the stepping motor 20 is transmitted to the binion carrier 18 via the worm 21 and the worm wheel 19, but the disturbance input to the handle 1 side and the wheels 8.8 side is transmitted to the differential gear. Transmission to the motor 20 via the mechanism 13 is prevented, and no load is applied to the output shaft 20a of the motor 20. As a result, when steering the steering wheel 1, the steered state of the wheels 8, 8 can be maintained with a small holding force of the stepping motor 20, and the holding force of the motor 20 can be reduced.

Further, each planetary pinion 16 in the differential gear mechanism 13 is divided into two divided gears 168.16a, and the divided gears r16a, 16a are urged to rotate in mutually opposite directions by the torsional force of the torsion spring 16b. So the difference #
Even if there is a dimensional error between the sun gear 14 and the link gear 15 of the J gear mechanism 13, it is absorbed and the sun gear 14
Also, backlash in the meshing of the teeth between the ring gear 15 and each planetary pinion 16 can be reduced, and backlash in the differential gear mechanism 13 can be effectively prevented.

In addition, a feedback device 24 is provided between the steering wheel 1 and the variable transmission ratio mechanism 9, which provides a responsive force to the steering of the steering wheel 1 by the spring force of the spiral springs 33, 33. The steering force of the steering wheel 1 can be increased appropriately and set within an appropriate range, and the operational feeling that the driver receives when steering the steering wheel can be improved.
The load on the variable transmission ratio mechanism 9 can be reduced due to the resistance caused by this.

Moreover, the spring shaft 25 of the feedback device 24 is connected to the handle 1.
The rotation of the handle 1 is decelerated and transmitted to the spring shaft 25, so that the spring shaft 2 is connected to the input shaft 12 connected to the
It is only necessary to rotate the spiral spring 5 approximately once in the left and right direction, and the spiral spring 3
3.33 makes it easy to set the response force, and it is possible to obtain a good response characteristic in which the response force increases symmetrically even when the steering wheel 1 is steered from the neutral position in either the left or right direction.

(Effects of the Invention) As described above, according to the present invention, there is provided a steering device for an automobile in which the transmission ratio of wheel steering angle to steering wheel steering angle is changed by a transmission ratio variable mechanism operated and controlled by an actuator. Since the power steering mechanism is provided between the variable ratio mechanism and the tie rod, the reaction force from the wheels can be reduced by the action of the steering assist force of the power steering mechanism, and the load torque applied to the actuator can be reduced.

[Brief explanation of the drawing]

The drawings show embodiments of the present invention, with Fig. 1 being a perspective view showing the overall configuration of the steering device, Fig. 2 being an enlarged vertical sectional view of the power steering mechanism, and Fig. 3 showing the variable transmission ratio mechanism and its surroundings. FIGS. 4 to 6 are cross-sectional views taken along lines IV-IV, v-v, and ■-■ in FIG. 3, respectively, and FIG. 7 is a block diagram showing the configuration of the controller. . 1... Steering handle, 6... Tie rod,
7... Power steering mechanism, 8... Wheels, 9...
...Variable transmission ratio mechanism, 20...Stepping motor,
40... Controller, 41... Steering wheel steering angle sensor, 42... Vehicle speed sensor. Figure 6 Figure 4 12 1! =1

Claims (1)

[Claims] (1) A variable transmission ratio mechanism that is provided in the steering force transmission path between the steering handle and the tie rod and that changes the transmission ratio of the wheel steering angle to the steering wheel angle, and a driving state detection means that detects the driving state of the vehicle. and a controller that inputs a signal from the detection means and outputs a control signal.
An automobile steering device comprising an actuator that controls the operation of the variable transmission ratio mechanism based on a control signal from the controller, wherein a power steering mechanism is provided between the variable transmission ratio mechanism and the tie rod. Characteristic automobile steering device.