JP2951376B2 - Electric power steering device - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an electric power steering apparatus, and more particularly, to an electric power steering apparatus provided with a correction means for an arbitrary purpose.

(Prior Art) An electric power steering apparatus has a configuration as shown in FIG. 15, for example. First, rack shaft 201
The rack shaft 201 is provided with a rack gear 203. Wheels 207, 207 are connected to both ends of the rack shaft 201 via links 205, 205.

A pinion gear 209 meshes with the rack gear 203, and a steering handle 213 is connected to the pinion gear 209 via a column shaft 211. At the position of the pinion gear 209, a torque sensor 215 is attached.

On the other hand, an assist pinion gear 217 meshes with the rack gear 203, and a drive motor 221 is connected to the assist pinion gear 217 via a speed reducer 219. The drive motor 221 is controlled by a controller 223, to which signals are input from the torque sensor 215 and the vehicle speed sensor 225 described above.

In the above configuration, first, the steering wheel 213 is rotated in an appropriate direction. The initial steering torque at this time is detected by the torque sensor 215. The detection signal of the torque sensor 215 is input to the controller 223.

The controller 223 calculates the power assist amount based on the detection signal, and outputs a control signal to the drive motor 221. As a result, the drive motor 221 rotates, and the speed reducer 2
Via 19, the assist pinion gear 217 rotates.

The rotation of the assist pinion gear 217 causes the rack gear 203 and thus the rack shaft 201 to move in an appropriate direction, whereby desired steering is performed.

On the other hand, the movement of the rack gear 203 causes the pinion gear 209 to rotate, so that the rotation is also fed back to the steering handle 213 via the column shaft 211.

(Problem to be Solved by the Invention) According to the above-described conventional configuration, there are the following problems.

That is, a disturbance (for example, gusts, punctures, unevenness of the road surface, etc.) during steering may cause the path of the vehicle to be shifted from the target path.

However, in the conventional electric power steering device, since there is no mechanism for correcting a course change caused by such a disturbance, the driving vehicle must correct the steering wheel 213 again in accordance with the deviation from the target. did not become.

In addition to correcting the course change due to such disturbance, it has been required to realize correction for improving high-speed stability, correction of steering phase delay, correction in accordance with vehicle speed, and the like.

The present invention has been made based on such a point. For example, an electric power steering device capable of improving steering stability during traveling by providing a correction means for correcting a course change caused by a disturbance. Is to provide.

(Means for Solving the Problems) The present invention provides an input device connected to a steering wheel,
A sun gear rotatably provided on the outer circumferences of the input shaft and the output shaft, and a sun gear provided on the outer circumference of the sun gear, while connecting the output shaft via a joint and linking a drive motor for applying a power assist force to the output shaft. And a ring gear having the same gear center as the sun gear, and a plurality of planet gears provided between the sun gear and the ring gear and meshing with the two gears and having the pin connected to the input shaft side. A group of planetary gears is provided on the outer periphery of the sun gear, a ring gear having the same gear center as the sun gear is provided between the sun gear and the ring gear, and the two gears mesh with each other, and the pin is provided on the output shaft side. A second planetary gear group consisting of a plurality of connected planet gears, and a ring gear of the first planetary gear group A torque sensor that detects an initial steering torque input via the steering wheel from a rotation amount of a ring gear, and a controller that controls an output of the drive motor based on a detection signal of the torque sensor. It is assumed that an electric power steering device is used.

On the premise of the above-mentioned device, the present invention relates to a ring gear of the second planetary gear group, which is linked to a correction means for rotating the ring gear, and the ring gear of the second planetary gear group is rotated by the correction means. The ring gear of the first planetary gear group is provided with a rotational force for correction.

(Operation) When an initial steering torque is input via the steering wheel, the input shaft rotates. At that time, since the rotation of the sun gear is regulated by the output shaft side, the planet gears of the first planetary gear group revolve, and thereby the ring gear rotates.

By the rotation of the ring gear, a torque sensor operates, and an initial steering torque is detected. Based on the detection signal, the controller calculates and drives the drive motor to output a power assist force corresponding to the initial steering torque.

The rotation is also fed back to the first planetary gear group. That is, when the output shaft rotates, the second
The planet gears of the planetary gear group revolve. At that time, the second
Since the rotation of the ring gear of the planetary gear group is regulated by the correction means, the sun gear rotates.

The rotation of the sun gear fixes the ring gear of the first planetary gear group, thereby maintaining the displacement position of the torque sensor. By such an operation, desired steering is performed.

When the input stops via the input shaft, the planet gears of the first planetary gear group stop revolving, so that the rotation of the sun gear causes the ring gear to rotate in the opposite direction, return to the initial neutral position, and perform steering. Is completed.

A correction means is attached to the ring gear of the second planetary gear group, and a rotational force for correction is applied as needed.

That is, when the rotational force is transmitted to the ring gear of the second planetary gear group by the correction means, the sun gear is rotated via the planet gears of the second planetary gear group, thereby changing the planet gears of the first planetary gear group. Through this, the ring gear rotates.

As a result, the torque sensor is operated, and the drive motor is driven by the same operation as described above, and the rotation for correction is output.

(Embodiment) A first embodiment of the present invention will be described below with reference to FIGS. FIG. 1 is a diagram showing a configuration of a main part of an electric power steering apparatus according to the present embodiment, in which a torque sensor mechanism 1 is installed. This torque sensor mechanism 1
Is provided with an input shaft 3 and an output shaft 5, and a joint 7
Are connected via The joint is capable of allowing a slight rotational deviation between the input shaft 3 and the output shaft 5.

A carrier 9a is formed on the input shaft 3, and a plurality of pins 11a are annularly arranged on the carrier 9a, and a plurality of planet gears 1
3a is rotatably mounted. A sun gear 15 is disposed on the outer periphery of the joint 7, and the plurality of planet gears 13 a are in mesh with the sun gear 15.

A ring gear 17a is arranged at an outer peripheral position of the plurality of planet gears 13a, and the plurality of planet gears 13a are in mesh with the ring gear 17a.
These planet gear 13a, sun gear 15, and ring gear 17a
Thus, a first planetary gear group 16a is configured.

On the other hand, the second planetary gear group 16 having the same configuration is also provided on the output shaft 5 side.
b are provided, and the same members are denoted by the same reference numerals and denoted by reference numeral b in the drawings.

A torque sensor 19 is provided at an outer peripheral position of the ring gear 17a.
Is arranged. That is, as shown in FIG.
An operating pin 21 is fixed to the outer periphery of the ring gear 17a, and the operating pin 21 is connected to a spool 25 slidably housed in a housing 23.

The spool 25 is held in a neutral position in the housing 23 by compression coil springs 27 and 29 arranged on both sides. A potentiometer 31 is provided on the left side of the spool 25 in the drawing.
Inside, the plunger 33 connected to the spool 25 protrudes and retracts.

The rotation of the ring gear 17a causes the spool 25 to move in any direction via the operation pin 21, whereby the position of the plunger 33 with respect to the potentiometer 31 changes. By detecting the change in electrical resistance at that time,
Detects torque (initial steering torque).

The detection signal of the torque sensor 19 is input to the controller 35. The controller 35 calculates the power assist amount based on the input detection signal, and outputs a control signal (current value signal) to the drive motor 37.

When the drive motor 37 rotates, a power assist force is applied via the assist pinion gear 39, and the rotation is fed back via the output shaft 5.

According to the above configuration, first, the initial steering torque is input via the input shaft 3. At that time, the output shaft 5 is
The input shaft 3 is rotated by a small amount within the allowable range of the joint 7 because it is connected and fixed to the load side via 37. Thereby, the plurality of planet gears 13a revolve around the sun gear 15 via the carrier 9a.

At that time, the rotation of the sun gear 15 is restricted because the output shaft 5 side is fixed, so that the ring gear 17a rotates. By the rotation of the ring gear 17a, the torque sensor 19 operates via the operation pin 21, and the initial steering torque is detected. Then, the drive motor 37 is driven by the controller 35, and a power assist force is applied via the assist pinion gear 39. Thereby, desired steering is performed.

On the other hand, the rotation of the drive motor 37 is also transmitted to the output shaft 5 side, whereby the plurality of planet gears 13b revolve around the sun gear 15 via the carrier 9b. At that time, since the rotation of the ring gear 17b is regulated by the correction means 41 described later, the sun gear 15 rotates.

The rotation of the sun gear 15 revolves the plurality of planet gears 13a, whereby the rotation is transmitted to the input shaft 3 via the carrier 9a (the time required for the sun gear 15 to start rotating is extremely long). The input shaft 3 continues to rotate at this stage.) That is, the rotation is fed back to the steering wheel.

By such feedback, the state where the ring gear 17a stops rotating and the operating pin 21 is urged is maintained. When the rotation of the input shaft 3 is continued, the ring gear 17a is stopped at the above position, the application of the power assist force is continued, and the input via the input shaft 3 is performed via the joint 7. It is transmitted to the output shaft 5 as it is.

Next, when the input via the input shaft 3 is stopped, the application of the power assisting force is continued because the operating pin 21 is biased at that time. Also, since the revolution of the planet gear 13a stops, the rotation of the sun gear 15 causes the ring gear to rotate.
17a rotates in the opposite direction. As a result, the operating pin 21 returns to the neutral position, and the application of the power assisting force is stopped. That is, the output shaft 5 stops rotating with an instant delay from the stop of the input rotation, and all states return to the initial position.

As described above, the desired steering is performed by the power assisting force of the drive motor 37 only by inputting a small amount of operating force by the input shaft via the steering wheel.

In the present embodiment, the correction means 41 is provided in the electric power steering device having such a configuration. Hereinafter, the configuration of the correction means 41 will be described.

First, a worm gear 43 meshes with the outer periphery of the ring gear 17b.
45 are connected.

On the other hand, as shown in FIG. 4, a yaw rate detector for detecting a yaw rate generated by a disturbance at an arbitrary position of the vehicle.
A yaw rate signal S47 from the yaw rate detector 47 is input to a deviation detector 49.
Further, a set yaw rate signal (operation control target value) S51 is input to the deviation detector 49 from the signal generator 51. The set yaw rate signal S51 is determined from the vehicle speed, the actual steering angle, the coefficient of friction, the coefficient of elasticity, etc., depending on the tire and road surface.

The deviation detector 49 calculates the deviation between these two signals, and outputs an adjustment signal S49 corresponding to the deviation to the amplifier 53, where it is amplified and output to the above-described correction motor 45. This causes the correction motor 45 to rotate, causing the worm gear 43 to rotate.

The rotation of the worm gear 43 rotates the ring gear 17b, and the rotation of the ring gear 17b rotates the sun gear 15 via the plurality of planet gears b.

The rotation of the sun gear 15 causes the ring gear 17a to rotate via the plurality of planet gears 13. The rotation of the ring gear 17a activates the torque sensor 19,
The power assist force for correction is exerted by the same operation as described above.

When the correction is completed, the output of the deviation detector 49 is stopped, so that the correction motor 45 stops its rotation, and the ring gear 17b is fixed. By such an operation, a predetermined correction is made, and the vehicle can be steered accurately with respect to the target value.

According to the present embodiment, the disturbance generated during the running of the vehicle,
In other words, even if there is a deviation from the target course due to gusts, punctures, road surface irregularities, etc., this can be corrected immediately.

Therefore, steering can be accurately performed on the target course, and steering stability during traveling can be improved.

Next, a second embodiment will be described with reference to FIG. This uses a clutch 55 which is normally OFF and turned ON at the time of correction, instead of the joint 7 in the first embodiment.

That is, the joint 7 of the first embodiment can tolerate a difference in rotation between the input shaft 3 and the output shaft 5 to some extent. Therefore, when the disturbance is small and the correction amount is small, the rotation of the output shaft 5 falls within the allowable range, and the rotation is not transmitted to the input shaft 3 side.

However, when the disturbance is large and the correction amount is large, the rotation amount of the output shaft 5 exceeds the allowable range. Therefore, the rotation is transmitted to the input shaft 3 side, that is, the steering wheel side. This is equivalent to the driver directly determining the situation and rotating the steering wheel to correct the situation.

Therefore, the rotation is not transmitted to the input shaft 3 in the correction embodiment by using the clutch 55 described above.

First, although normally, since the switching valve 57 has been switched to the switching position a, the cylinder chamber 63,
The same fluid pressure acts on 65. Therefore, the urging force to the left in the figure is increased by the spring force of the compression coil spring 67, so that the clutch plates 69 and 71 are engaged and the input shaft 3 and the output shaft 5 are connected (clutch). OFF).

On the other hand, at the time of correction, the switching valve 57 switches to the switching position b, and the pressure on the cylinder chamber 63 side increases. As a result, the clutch plate 71 is urged rightward in the figure against the spring force of the compression coil spring 67, and the clutch plates 69, 71
Are separated, and the input shaft 3 and the output shaft 5 are separated (clutch ON).

Therefore, even if a large disturbance occurs during the correction and the correction amount increases, the rotation on the output shaft 5 side is not transmitted to the input shaft 3 side, and the above-described inconvenience does not occur.

Next, a third embodiment will be described with reference to FIG. This is a modification of the configuration of the correction means 41. That is,
A rack gear 73 is used in place of the worm gear 43 in the first embodiment, and a linear actuator 75 is used in place of the correction motor 45.

Even in such a configuration, the same operation and effect can be obtained.

Next, a fourth embodiment will be described with reference to FIG. This embodiment provides an appropriate steering feeling at high speed.

In general, during high-speed running, the ground resistance decreases and the steering wheel becomes lighter. In such a case, the steering becomes more stable when the power assist force is reduced.

Therefore, as shown in FIG. 7, a vehicle speed is detected by a vehicle speed detector 77, a current value is detected by a current detector 79, and an adjustment signal is output by an adjuster 81 based on a difference between these two signals. . The adjustment signal is amplified by the amplifier 83 and output to the correction motor 45 of the correction unit 41.

Therefore, when steering at a certain speed, when the set current is reached, an adjustment signal is output from the adjuster 81, and
The rotation of the drive motor 45 of 41 causes the rotation to be corrected via the ring gear 17b.

As a result, compared to the input rotation of the input shaft 3, the ring gear
If the feedback speed via 17b is equal or greater (during high-speed running), the power assisting force is reduced, and the steering wheel does not become too light, so that an appropriate steering feeling can be provided.

Conversely, a large power assist force can be obtained during low-speed running.

Next, a fifth embodiment will be described with reference to FIG. This embodiment is intended to correct a phase delay of steering. First, a turning angle detector 85 that detects a turning angle is grounded. An attitude angle detector 87 for detecting the actual attitude angle or lateral acceleration of the vehicle is provided.

The difference between the detection signals of both detectors 85 and 87 is calculated by adjuster 89.
And outputs an adjustment signal. The adjustment signal is
The signal is amplified by the amplifier 91 and output to the correction motor 45 of the correction unit 41. Thereby, the phase delay of the steering is corrected.

Next, a sixth embodiment will be described with reference to FIG. As in the case of the fifth embodiment, this embodiment also attempts to correct the steering phase delay.

First, a vehicle speed detector 93 and a turning angle detector 95 are laid on the ground, and the adjuster 97 receives the detection signals of the two detectors 93 and 95, calculates the deviation thereof, and outputs an adjustment signal. The adjustment signal is amplified by the amplifier 99 and output to the correction motor 45 of the correction means 41.

Thereby, in the low-speed running embodiment, the output for the input is increased and the steering wheel is made light, and at the time of high-speed running, the output for the input is reduced and the steering wheel is made heavy.

Next, a seventh embodiment will be described with reference to FIG. In this embodiment, a function of so-called differential steering is provided.

Since the steering of a normal vehicle is an integration mechanism,
When turning, the driver must sense the speed, turning angle, and the like of the vehicle and perform a differential operation. That is, if the steering wheel is turned by a certain angle in order to change the direction, an operation of returning the steering wheel to the original position is required before the direction of the vehicle is completely changed.

Therefore, in the case of this embodiment, if the operation of turning the steering wheel is stopped when the vehicle turns in a predetermined direction, the vehicle can be driven in the desired direction without the need to return the steering wheel to its original state. The differential handle function is provided.

That is, as shown in FIG. 10, the yaw rate detector 10
1. An input speed detector 103, an input acceleration detector 105, and an input direction detector 107 are provided. Also, install adjuster 109,
An adjustment signal is output based on the detection signals from the detectors 101 to 107.

The adjustment signal is amplified by the amplifier 111 and the correction means 41
Is output to the correction motor 45. Thereby, a correction input as shown in FIG. 11 is given.

As a result, the driving situation of the vehicle is as shown in FIG. FIG. 13 shows the relationship shown in FIG. As described above, according to this embodiment, it is possible to provide a function close to that of the differential steering.

Next, an eighth embodiment will be described with reference to FIG. In this embodiment, for example, automatic steering is performed based on a command from a guidance signal generator buried in a road.

First, there is a guidance signal detector 113, and the detection signal of the guidance signal detector 113 is amplified by the amplifier 115. The output is output to the correction motor 45 of the correction means 41 to perform desired steering.

That is, for example, when the guidance signal detector 113 detects a guidance signal “turn right”, the input shaft 3
Steering is performed regardless of the input from the side.

The present invention is not limited to the above embodiments, and various configurations are conceivable as to the configuration of the correction means and the basis for performing correction.

(Effects of the Invention) As described in detail above, according to the electric power steering apparatus of the present invention, the correcting means is attached to the ring gear of the second planetary gear group, and the steering state is corrected by the correcting means, so that the stability is improved. Steering can be performed, thereby improving the steering stability during traveling.

[Brief description of the drawings]

1 to 4 show a first embodiment of the present invention.
FIG. 1 is a configuration diagram of a main part of an electric power steering device,
FIG. 2 is a sectional view taken along the line II-II of FIG. 1, and FIG.
-III sectional view, FIG. 4 is a functional block diagram showing the operation of the correcting means, FIG. 5 is a configuration diagram of a clutch according to the second embodiment,
FIG. 6 is a block diagram of the correcting means according to the third embodiment, FIG. 7 is a functional block diagram showing the fourth embodiment, FIG. 8 is a functional block diagram showing the fifth embodiment, and FIG. 9 is a sixth embodiment. FIG. 10 is a functional block diagram showing an example, FIG. 10 to FIG. 13 are diagrams showing a seventh embodiment, FIG. 10 is a functional block diagram, FIG. 11 to FIG. Is a functional block diagram showing an eighth embodiment, and FIG. 15 is a configuration diagram of a power steering showing a conventional example. 3 ... input shaft, 5 ... output shaft, 7 ... coupling, 13a, 13b ...
... planet gear, 15 ... sun gear, 16a ... first planetary gear group, 16b ... second planetary gear group, 17a, 17b ... ring gear, 19 ... torque sensor, 35 ... controller, 37 ...
Drive motor, 41... Correction means.

──────────────────────────────────────────────────続 き Continuation of front page (56) References JP-A-59-11965 (JP, A) JP-A-61-41670 (JP, A) JP-A-2-310174 (JP, A) JP-A 64-64 74190 (JP, A) Japanese Utility Model Showa 59-9974 (JP, U) (58) Field surveyed (Int. Cl. ⁶ , DB name) B62D 5/04

Claims (1)

(57) [Claims] An input shaft connected to a steering wheel is connected to an output shaft via a joint, and a drive motor for applying a power assist force to the output shaft is connected to the input shaft. A sun gear rotatably provided on the outer periphery of the sun gear, a ring gear provided on the outer periphery of the sun gear and having the same gear center as the sun gear, provided between the sun gear and the ring gear, meshed with both of these gears, and A first planetary gear group consisting of a plurality of planet gears connected to the input shaft side, provided on the outer periphery of the sun gear, a ring gear having the same gear center as the sun gear, and provided between the sun gear and the ring gear; Mesh with both these gears,
In addition, the pin is provided on a second planetary gear group including a plurality of planet gears connected to the output shaft side and a ring gear of the first planetary gear group, and an initial steering input through the steering handle is provided. An electric power steering apparatus comprising: a torque sensor for detecting a torque from a rotation amount of a ring gear; and a controller for controlling an output of the drive motor based on a detection signal of the torque sensor, wherein a ring gear of the second planetary gear group is provided. In addition, a correction means for rotating the ring gear is linked, and the correction means rotates the ring gear of the second planetary gear group to apply a correction torque to the ring gear of the first planetary gear group. An electric power steering device characterized by the above-mentioned.