JPH0487881A - Electric power steering device - Google Patents

Abstract

PURPOSE:To improve the stability of steering during the running of a car by additively providing a correcting means for giving correcting torque to the ring gear of the second epicycloidal gear train, for instance, to correct an alteration in a route caused by disturbance. CONSTITUTION:When initial steering torque is inputted into a torque sensor mechanism 1, an input shaft rotates a little within the allowable range of a coupling 7, and revolves round plural planted gears 13a and a sun gear 15 through a carrier 9a. A ring gear 17a rotates to actuate a torque sensor 19 through an actuating pin 21. In addition to that, a controller 35 controls a driving motor 37 on the result of the detection of the initial steering torque to give power assisting force through an assistant pinion 39. In this case, a worm gear 43 is meshed the periphery of a rig gear 17b, and a driving motor 45 is connected with the worm gear 43. Thus A correcting means 41 to give correcting torque is thereby composed.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to an electric power steering device, and in particular,
This invention relates to a device equipped with a correction means suitable for an arbitrary purpose.

(Prior Art) An electric power steering device has a configuration as shown in FIG. 15, for example. First, rack shaft 20
1 is installed on this rack shaft 201,
A rack gear 203 is provided. Further, 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. Further, a torque sensor 215 is attached at the position of the pinion gear 209.

On the other hand, an assist pinion gear 217 is meshed with the rack gear 203.
A drive motor 221 is connected to 17 via a reduction gear 219 . This drive motor 221 is controlled by a controller 223, and the controller 223 includes:
Signals are input from the already mentioned torque sensor 215 and vehicle speed sensor 225.

In the above configuration, first, the steering handle 213 is rotated in an appropriate direction. A detection signal from the torque sensor 215, which detects the initial steering torque at this time, is input to the controller 223.

The controller 223 calculates a power assist amount based on the detection signal, and outputs a control signal to the drive motor 221. As a result, drive motor 221 rotates, and assist pinion gear 217 rotates via reduction gear 219.

The rotation of the assist pinion gear 217 moves the rack gear 203 and thus the rack shaft 201 in an appropriate direction, thereby achieving desired steering.

On the other hand, since the pinion gear 209 also rotates due to the movement of the rack gear 203, the rotation is also fed back to the steering handle 213 via the column shaft 211.

(Problem to be solved by the invention) The conventional configuration described above has the following problems.

That is, during steering, the course of the vehicle may deviate from the target course due to disturbances (for example, gusts of wind, flat tire, unevenness of the road surface, etc.).

However, conventional electric power steering devices do not have a mechanism to correct course changes caused by such disturbances, so the driver has to correct the steering wheel 213 again in response to the deviation from the target. did not become.

In addition to correcting course changes caused by such disturbances, there has also been a demand for corrections to improve high-speed stability, corrections for steering phase delays, corrections according to vehicle speed, and the like.

The present invention has been made based on the above points, and provides an electric power steering device that can improve steering stability during driving by, for example, providing a correction means for correcting course changes caused by disturbances. Our goal is to provide the following.

(Means for Solving the Problems) In order to achieve the above object, an electric power steering device according to the present invention includes an input shaft connected to a steering wheel side, a drive motor that exerts a power assist force, and An output shaft connected to the input shaft via a joint, a plurality of planet gears connected to the input shaft side and arranged in a ring, and an inner peripheral side arranged on the outer periphery of the joint and connected to the plurality of planet gears. a first planetary gear group consisting of a sun gear in mesh with the plurality of planet gears and a ring gear disposed on the outer periphery of the plurality of planet gears and meshed with the plurality of planet gears; A plurality of planet gears meshing with the sun gear of one planetary gear group from the outer circumferential side, and a plurality of the above-mentioned branes.
A second planetary gear group consisting of a ring gear disposed around the outer periphery of the gear and meshed with a plurality of planet gears, and a ring gear of the first planetary gear group are provided to detect an initial steering torque input through the steering handle. a torque sensor that drives the drive motor based on the detection signal of the torque sensor to output a desired power assist force, and a controller that is attached to the ring gear of the second planetary gear group and that is used for correction via the ring gear. The present invention is characterized by comprising a correction means for applying a rotational force of.

(Function) When initial steering torque is input via the steering handle, the input shaft rotates. At this time, since the rotation of the sun gear is restricted by the output shaft side, the planet gears of the first planetary gear group revolve, thereby causing the ring gear to rotate.

The rotation of the ring gear activates a torque sensor and detects the initial steering torque. Based on the detection signal, the controller calculates and drives the drive motor,
A power assist force matching the initial steering torque is output.

Further, the rotation is also fed back to the first planetary gear group. In other words, as the output shaft rotates, the planet gears of the second planetary gear group revolve.At this time, since the rotation of the ring gear of the second planetary gear group is restricted 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. Desired steering is achieved by such an action.

Furthermore, if the input via the input shaft stops, the revolution of the planet gears in the first planetary gear group will stop, so the rotation of the sun gear will cause the ring gear to rotate in the opposite direction, returning to the initial neutral position, and steering. is completed.

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

That is, when the correction means transmits the rotational force to the ring gear of the second planetary gear group, the sun gear is rotated via the planet gear of the second planetary gear group, and thereby,
The ring gear rotates via the planet gears of the first planetary gear group.

As a result, the torque sensor is actuated, and the drive motor is driven by an effect similar to that described above, thereby outputting correction rotation.

(Embodiment) Hereinafter, a first embodiment of the present invention will be described with reference to FIGS. 1 to 4. FIG. 1 is a diagram showing the configuration of main parts of an electric power steering device according to the present embodiment. , a torque sensor mechanism 1 is installed.In this torque sensor mechanism 1, an input shaft 3 and an output shaft 5 are arranged, and are connected via a joint 7.The joint 7 is connected to the input shaft 3. A slight rotational deviation between the output shaft 5 and the output shaft 5 can be tolerated.

A carrier 9a is formed on the input shaft 3, and a plurality of pins 11a are arranged in an annular manner on this carrier 9a, and a plurality of planet gears 13a are rotatably arranged around these pins lla. installed. Further, a sun gear 15 is arranged on the outer periphery of the joint 7, and the plurality of planet gears 13a are connected to the sun gear 15.
There is a relationship that meshes with the

A ring gear 17a is arranged on the outer periphery of the plurality of planet gears 13a, and the plurality of planet gears 13a also mesh with this ring gear 17a. These planet gear 13a, sun gear 15,
The ring gear 17a constitutes a first planetary gear group 16a.

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

A torque sensor 1 is provided on the outer periphery of the ring gear 17a.
9 has been installed. That is, as shown in FIG. 2, 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 located inside the housing 23 and is operated by compression coil springs 2729 disposed on both sides.
held in a neutral position. A potentiometer 31 is installed on the left side of the spool 25 in the figure, and a plunger 33 connected to the spool 25 retracts into the potentiometer 31.

Then, due to the rotation of the ring gear 17a, the operating bin 21
, the spool 25 moves in either direction, thereby changing the position of the plunger 33 relative to the potentiometer 31. Torque (initial steering torque) is detected by detecting the change in electrical resistance at that time.

The detection signal of the torque sensor 19 is transmitted to the controller 35.
is input. The controller 35 calculates the power assist amount based on the input detection signal, and controls the drive motor 3.
A control signal (current value signal) is output to 7.

As 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 connected to the drive motor 3
Since the input shaft 3 is connected to the load side via the joint 7 and is fixed, the input shaft 3 rotates only a small amount within the allowable range of the joint 7. Thereby, the plurality of planet gears 13a revolve around the sun gear 15 via the carrier 9a.

At this time, since the output shaft 5 side of the sun gear 15 is fixed, its rotation is restricted, so that the ring gear 17a rotates.

The rotation of the ring gear 17a causes the torque sensor 19 to operate via the operating 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. As a result, desired steering is achieved.

On the other hand, the rotation of the drive motor 37 is also transmitted to the output shaft 5 (11), thereby causing the plurality of planet gears 13b to revolve around the sun gear 15 via the carrier 9b. Correction means 41
Since its rotation is regulated by
will rotate.

The rotation of the sun gear 15 causes the plurality of planet gears 13a to revolve, thereby transmitting the rotation to the input shaft 3 via the carrier 9a.
The time it takes for the machine to start rotating is extremely short;
At that stage, the input shaft 3 continues to rotate). In other words, the rotation is fed back to the steering wheel.

Due to such feedback, the ring gear 17a stops rotating, and the state in which the operating pin 21 is energized is maintained. Also, if the input shaft 3 continues to rotate,
The ring gear 17a is stopped at the above position, and the power assist force continues to be applied, and the input shaft 3
The input via is transmitted directly to the output shaft 5 via the joint 7.

Next, when the input via the input shaft 3 is stopped, since the actuating pin 21 is energized at that point, the application of the power assist force is continued. Furthermore, since the planet gear 13a stops rotating, the rotation of the sun gear 15 causes the ring gear 17a to rotate in the opposite direction. As a result, the operating bin 21 returns to the neutral position, and application of the power assist force is stopped. In other words, the output shaft 5 stops rotating with an instant delay after the input rotation stops, and all states return to their initial positions.

In this way, by simply inputting a small operating force from the input shaft through the steering handle, the desired steering is then performed by the power assist force from the drive motor 37.

In this embodiment, a correction means 41 is provided in the electric power steering device having such a configuration. The configuration of this correction means 41 will be explained below.

In addition, a worm gear 43 is provided on the outer periphery of the ring gear 17b.
are in mesh with each other, and the drive motor 4 and the like are connected to the worm gear 43.

On the other hand, as shown in FIG. 4, a yaw rate detector 4 is installed at an arbitrary location on the vehicle to detect the yaw rate caused by disturbance.
7 is installed, and the detected yaw rate signal S47 from this yaw rate detector 47 is input to the deviation detector 49. Further, a set yaw rate signal (operation control target value) 851 is inputted to the deviation detector 49 from the signal generator 51.

This set yaw rate signal S51 is determined from the vehicle speed, the actual steering angle of the tires, the coefficient of friction and the coefficient of elasticity due to the road surface, and the like.

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 drive motor 45 described above. This causes the drive motor 45 to rotate, causing the worm gear 43 to rotate.

Due to the rotation of the ohm gear 43, the ring gear 17b
The rotation of the ring gear 17b causes the sun gear 15 to rotate via the several sub planet gears 13b.

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

When the correction is completed, the output of the deviation detector 49 stops, the drive motor 45 stops rotating, and the ring gear 17b is fixed. Due to this effect,
A predetermined correction is made, and the vehicle can be accurately steered to the target value.

As described above, according to this embodiment, even if a deviation from the target course occurs due to disturbances occurring while the vehicle is running, such as a gust of wind, a puncture, or unevenness of the road surface, this can be immediately corrected.

Therefore, it becomes possible to accurately steer the vehicle along the target course, and the 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 turns ON during correction, in place of the joint 7 in the first embodiment.

That is, the joint 7 of the first embodiment has the input shaft 3 and the output shaft 5.
A certain degree of rotation difference between the two can be tolerated. Therefore, when the disturbance is small and the correction amount is small, the output shaft 5
Since the rotation is within the above-mentioned allowable range, no rotation is transmitted to the input shaft 3 side.

However, if the disturbance is large and the amount of correction is large, the amount of rotation of the output shaft 5 may exceed the above-mentioned allowable range.

Therefore, the rotation is transmitted to the input shaft 3 side, that is, to the steering handle side. This would be equivalent to the driver directly judging the situation and rotating the steering wheel to make a correction.

Therefore, the already described clutch 55 is used to prevent rotation from being transmitted to the input shaft 3 side during correction.

First, in normal times, since the switching valve 57 is switched to the switching position a, the same fluid pressure acts on the cylinder chamber 63.65 via the boat 59.61. Therefore, the biasing force to the left side in the figure increases by the spring force of the compression coil spring 67, so the clutch plates 69 and 71 are engaged and the input shaft 3 and output shaft 5 are connected (clutch OFF>.

On the other hand, during correction, the switching valve 57 is switched to the switching position, and the pressure on the cylinder chamber 63 side increases. As a result, the clutch plate 71 is urged to the right side in the figure against the spring force of the compression coil spring 67, and the clutch plates 69 and 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 correction and the amount of correction becomes large, the rotation on the output shaft 5 side will not be transmitted to the input shaft 3 side, and the above-mentioned problems will 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 instead of the ohm gear 43 in the first embodiment, and a linear actuator 75 is used instead of the drive motor 45.

Even in the case of such a configuration, similar actions and effects can be achieved.

Next, a fourth embodiment will be described with reference to FIG. 7. This embodiment provides an appropriate steering feel at high speeds.

Generally, when driving at high speed, ground resistance decreases and the steering becomes lighter. In such a case, steering will be more stable if the power assist force is reduced.

Therefore, as shown in FIG. 7, a vehicle speed detector 77 detects the vehicle speed, a current detector 79 detects the current value, and an adjuster 81 outputs an adjustment signal based on the difference between these two signals. . The above adjustment signal is sent to the amplifier 8
3 and output to the drive motor 45 of the correction means 41.

Therefore, when steering at a certain speed and the set current is reached, the adjuster 81 outputs the N adjustment signal, the drive motor 45 of the correction means 41 rotates, and correction rotation is applied via the ring gear 17b.

As a result, compared to the input rotation of the input shaft 3, the ring gear 1
If the feedback speed via 7b is equal or large (during high-speed driving), the power assist force will be reduced, the steering wheel will not become too light, and an appropriate steering feeling can be provided.

On the other hand, when driving at low speeds, a large power assist force can be obtained.

Next, a fifth embodiment will be described with reference to FIG. 8. This embodiment attempts to correct a phase delay in steering. First, a turning angle detector 85 for detecting a turning angle is installed. Additionally, an attitude angle detector 87 is installed to detect the actual attitude angle or lateral acceleration of the vehicle.

The adjuster 89 calculates the deviation between the detection signals of both the detectors 85 and 87 and outputs an adjustment signal. The adjustment signal is amplified by the amplifier 91 and output to the drive motor 45 of the correction means 41, thereby correcting the phase delay in steering.

Next, a sixth embodiment will be described with reference to FIG. 9. Similar to the fifth embodiment, this embodiment is intended to correct the phase delay in steering.

First, a vehicle speed detector 93 and a steering angle detector 95 are installed, and the adjuster 97 inputs detection signals from these two detectors 93 and 95, calculates a deviation thereof, and outputs an adjustment signal. The adjustment signal is amplified by an amplifier 99 and output to the drive motor 45 of the correction means 41.

As a result, when driving at low speeds, the output relative to the input is increased, making the steering wheel light, and when driving at high speeds, the output relative to the input is reduced, making the steering wheel heavy.Next, as shown in Figure 10, The seventh embodiment will be explained with reference to the following. This embodiment is intended to provide a so-called differential steering function.

Since the steering of a normal vehicle is an integral mechanism, when steering the vehicle, the driver must sense the speed, steering angle, etc. of the vehicle and perform differential operation.

In other words, if you turn the steering wheel by a certain angle to change the direction, you must return the steering wheel to its original position before the vehicle's direction has completely changed.

Therefore, in the case of this embodiment, if you stop turning the steering wheel when the vehicle turns in a predetermined direction, it is possible to drive the vehicle in the desired direction without having to return the steering wheel to its original position. This provides a differential handle function that can be used.

That is, as shown in FIG.
01, input speed detector 103, input acceleration detector 105
, an input direction detector 107 is provided, and an adjuster 10 is provided.
9 is installed to output an adjustment signal based on the detection signals from each of the detectors 101 to 107.

The adjustment signal is amplified by the amplifier 111 and then sent to the correction means 4.
The signal is output to the drive motor 45 of No. 1. Thereby, the first
A correction input as shown in FIG. 1 is provided.

As a result, the driving situation of the vehicle becomes as shown in FIG. Further, the relationship shown in FIG. 12 is shown in FIG. 13. In this way, according to this embodiment, it is possible to provide a function similar to differential steering.

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

First, there is a guided signal detector 113, and a detection signal of this guided signal detector 113 is amplified by an amplifier 115.

The signal is then output to the drive motor 45 of the correction means 41 to perform desired steering.

In other words, when the guidance signal detector 113 detects a guidance signal such as "turn right", the steering is performed along that signal regardless of the input from the input shaft 3 side.

It should be noted that the present invention is not limited to the above embodiments,
Various configurations are possible regarding the configuration of the correction means and the criteria used for correction.

(Effects of the Invention) As detailed above, according to the electric power steering device according to the present invention, the correction means is attached to the ring gear of the second planetary gear group, and the correction means corrects the steering state, so that the steering condition is stabilized. Steering becomes possible, thereby improving steering stability during driving.

[Brief explanation of the drawing]

1 to 4 are diagrams showing a first embodiment of the present invention,
Figure 1 is a configuration diagram of the main parts of the electric power steering device.
Figure 2 is a sectional view taken from ■-■ in Figure 1, and Figure 3 is a cross-sectional view taken from ■-■ in Figure 1.
■Cross-sectional view, FIG. 4 is a functional block diagram showing the action of the correction means, FIG. 5 is a block diagram of the Kura Sochi according to the second embodiment, FIG. 7 is a functional block diagram showing the fourth embodiment, FIG. 8 is a functional block diagram showing the fifth embodiment, FIG. 9 is a functional block diagram showing the sixth embodiment, and FIGS. FIG. 10 is a functional block diagram, and FIGS. 11 to 1 are diagrams showing seven embodiments.
FIG. 3 is a diagram showing the contents of correction, FIG. 14 is a functional block diagram showing an eighth embodiment, and FIG. 15 is a configuration diagram of an electric power steering system showing a conventional example. 3...Input shaft, 5...Output shaft, 7...Joint, 13
a, 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. Applicant's Representative Patent Attorney Nobuyuki ShimaFigure 2Figure 3Figure 5Figure 6Figure 12Figure 10Figure 15

Claims (1)

[Scope of Claims] An input shaft connected to the steering handle side, an output shaft connected to the drive motor that exerts power assist force and connected to the input shaft via a joint, and the input shaft side a plurality of planet gears connected to each other and arranged in an annular shape, a sun gear arranged on the outer periphery of the joint and meshing with the plurality of planet gears from the inner circumferential side, and a plurality of sun gears arranged on the outer periphery of the plurality of planet gears. a first planetary gear group consisting of a ring gear meshed with planet gears, and a plurality of planet gears connected to the output shaft side and arranged in an annular shape and meshed with the sun gear of the first planetary gear group from the outer circumferential side. and a ring gear disposed on the outer periphery of the plurality of planet gears and meshed with the plurality of planet gears; and a ring gear provided on the ring gear of the first planetary gear group and inputted via the steering handle. a torque sensor that detects the initial steering torque to be used; a controller that drives the drive motor to output a desired power assist force based on the detection signal of the torque sensor; and a controller that is attached to the ring gear of the second planetary gear group. An electric power steering device comprising: a correction means that applies a rotational force for correction via the ring gear.