JPS63215465A - Power steering device - Google Patents

Abstract

PURPOSE:To eliminate the hitched feeling in handle operation by eliminating the delay of response of the auxiliary steering torque in the transition from the rudder holding state to the steering state by turning a steering wheel when the car speed exceeds a set value in the rudder holding state. CONSTITUTION:A calculation processing unit 22c judges if the absolute value of the steering speed thetaS which is obtained by differentiating the steering detection value theta of a steering angle sensor 18 is below a prescribed set value betaor less, when the actual steering torque detection value TSD supplied into an input circuit 22a is over a prescribed value alpha, and judges the rudder holding state. If the car speed detection value is over a prescribed set value gamma in the rudder holding state or in the steering state, the actual steering torque detection value TSD and the differentiation value T'SD of the actual steering torque calculated from the detection value TSD are adopted as the steering torque detection value and the differentiation value of the steering torque, and the steering auxiliary torque TM is calculated on the basis of the above-described values, and an electric motor control signal is outputted on the basis of the torque TM.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a power steering device in which steering force is assisted by the output of an auxiliary force generating means, and in which a particularly stable steering feeling can be obtained. It is.

[Conventional technology]

As a conventional power steering device, there is one described, for example, in Japanese Unexamined Patent Publication No. 59-63264.

In this system, an electric motor, which provides steering assist torque, is coupled to the steering shaft of the steering system via a reduction gear mechanism, and the electric motor is energized and controlled according to the steering torque detected by a steering torque detection means, and the vehicle speed is controlled. is detected by a vehicle speed detection means, and when the detected value exceeds a predetermined set value, energization of the electric motor is prohibited.

However, in such a conventional power steering device, since the steering assist torque by the electric motor is determined only based on the steering torque detected by the steering torque detection means, the steering can be maintained at the desired steering torque value. When the steering torque is being adjusted, there may be slight fluctuations in the steering torque detected by the steering torque detection means, or there may be a reading error in the detected steering torque value due to a bit error, etc. on the control device side that controls the electric motor based on the detected steering torque value. If this occurs, it is determined that there has been a fluctuation in the detected steering torque value, and the steering assist torque by the electric motor is changed, and the reduction gear mechanism inserted between the steering system and the electric motor is configured. If there is backlash, play, or other misalignment in the worm gear, pinion gear, etc., a rumbling noise and vibrations are generated, and this vibration is transmitted to the steering wheel of the steering system, worsening the steering sensation. There was a problem with that.

Therefore, as a means to solve the above-mentioned problems, the applicant of the present invention previously disclosed in Japanese Patent Application No. 184497/1987 an electric motor coupled to a steering system via a reduction gear mechanism, and a direction of steering torque in the steering system. a steering torque detecting means for detecting the magnitude of the steering torque, a steering angle detecting means for detecting the steering angle, and a steering angle detecting means for detecting the steering angle; and a steering angle detecting means for detecting the steering angle; A power steering device comprising a torque control means for controlling an output torque, further comprising a held steering state detection means for detecting a held steering state of the steering system, and when the held steered state is detected by the held steering state detection means. , by setting a steering torque value that is an average value of the actual steering torque detection values detected by the steering torque detection means or a value obtained by removing high frequency components, and controlling the electric motor based on this steering torque value. proposed a method to improve the steering sensation by eliminating minute vibrations in the steering assist torque generated by the electric motor during the steering-holding state.

[Problem that the invention seeks to solve]

However, in the prior art according to the prior application, when the steering is in the holding state, the steering torque value is based on the average value of the actual steering torque detection value detected by the steering torque detection means or the value obtained by removing the high frequency component. Therefore, when the steering condition changes from the steering condition to the steering condition, especially when the vehicle speed is high, there is a delay in the response of the steering assist torque, making it difficult for the operator to operate the steering wheel. There was a problem in that the player felt a sense of ``kakashi''.

[Means for solving problems]

The present invention aims to solve the above problems. As shown in the basic configuration diagram of FIG. 1, the present invention includes an auxiliary force generating means that provides a steering assist torque in conjunction with a steering system, and a steering system that detects the direction and magnitude of the steering torque in the steering system. a torque means, a steering angle detection means for detecting a steering angle, a held steering state detection means for detecting a held steering state, a vehicle speed detection means for detecting a vehicle speed, and a vehicle speed of the vehicle speed means and an actual steering of the steering torque means. A power steering system comprising: a torque control means for controlling the output torque of the auxiliary force generating means based on a torque detection value, a steering angle detection value of the steering angle detection means, and a steering state detected by the steering state detection means. In the device, when the held steering state is detected by the held steering state detection means and the vehicle speed detected by the vehicle speed detection means is equal to or less than a predetermined set value, the average value of the actual steering torque detection value of the steering torque means is determined. Or, when the vehicle speed of the vehicle speed detection means exceeds a predetermined set value, k is the actual steering torque detection value of the steering torque detection means and i actual steering torque detection. The torque control means is configured to control the steering assist torque of the assist force generating means based on a value consisting of a differential value or a difference value of the actual steering torque calculated from the value. be.

In this invention, when the held steering state is detected by the held steering state detection means and the vehicle speed detected by the vehicle speed detection means is less than a predetermined set value, the average value or high frequency value of the actual steering torque detected by the steering torque detection means is set. When the vehicle speed of the vehicle speed detection means exceeds a predetermined setting value, the actual steering torque value is calculated from the actual steering torque detection value of the steering torque detection means and this actual steering torque detection value. The output torque of the auxiliary force generating means is controlled based on the differential value or the difference value of the torque. Therefore, when the vehicle speed exceeds the set value while the steering is held, the driver
When the wheel is rotated to shift from the holding state to the steering state, there is no delay in response of the steering assist torque, so it is possible to eliminate the ``sluggish feeling'' when the driver operates the steering wheel.

〔Example〕

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

FIGS. 2 to 6 are diagrams showing an embodiment of the present invention.

In Fig. 2, 10 is the component part of the steering system, 11
12 is a reduction gear mechanism consisting of a worm wheel 12a attached to the stub shaft 11 and a worm gear 12b that meshes with the worm wheel 12a; 13 is formed at the end of the stub shaft 11; This pinion gear 13 is connected to the wheels via a rack 14 that meshes with the pinion gear 13 and further via a steering link mechanism (not shown).

Reference numeral 15 denotes a DC servo motor as an auxiliary force generating means for adding a steering assist torque to the steering system 10, and is connected to the steering system 10 via an electromagnetic clutch 15a and a worm gear 12b fixed to its output shaft.

A vehicle speed sensor 16 serves as vehicle speed detection means, and detects, for example, the rotational speed of an output shaft of a transmission and outputs a pulse signal with a period corresponding to the rotational speed.

Reference numeral 17 denotes a steering torque sensor as a means for detecting steering torque, which is composed of, for example, a strain gauge fixed to the steering shaft, and is capable of detecting the magnitude and direction of twist that occurs in the steering shaft when the driver steers the steering wheel. Outputs the corresponding analog voltage.

Reference numeral 18 denotes a steering angle sensor as a steering angle detection means for detecting a steering angle, which is a rotating sensor consisting of a disc with a slit attached to the steering shaft and a photocoupler having two sets of detectors facing the slit. It is composed of a detector and outputs a steering angle detection signal that is a pulse signal according to the rotation direction and rotation speed of the steering shaft.

Reference numeral 19 denotes a control device as a control means, to which detection signals from the vehicle speed sensor 16, the steering torque sensor 17, and the steering angle sensor 18 are supplied, and control signals S1 to S3 for controlling the electric motor 15 based on these are supplied. and a control circuit 20 that outputs a control signal S4 that controls the electromagnetic clutch 15a, and a motor drive circuit 30 that is supplied with the control signals 81 to S3 and drives the electric motor 15 based on the control signals 81 to S3.

The control circuit 20, as shown in FIG.
, a microcomputer 22 and a D/A converter 23.

The microcomputer 22 includes an input circuit 22a1 as an interface circuit, an output circuit 22b, and an arithmetic processing unit 2.
2c and a storage device 22d, the input circuit 2
The detection signals of the sensors 16 and 18 are directly supplied to 2a, and the detection signals of the sensor 17 are supplied via the converter 21, and a motor current control signal S1 corresponding to the steering assist torque is supplied from the output circuit 22b. is outputted via the D/A converter 23, and control signals 82 to S4 are outputted directly.

The arithmetic processing unit 22c calculates a steering speed θS obtained by differentiating the steering angle detection value θ of the steering angle sensor 18 based on the actual steering torque detection value TSD supplied to the input circuit 22a, when the actual steering torque detection value TSD is greater than or equal to a predetermined set value α. It is determined whether or not the absolute value is less than or equal to a predetermined set value β to determine whether or not the steering is held, and when the steering is held, the vehicle speed is further detected by the vehicle speed sensor 16, and the vehicle speed is detected. When the value is less than the predetermined set value γ, the actual steering torque detection value T is set as the steering torque detection value Ts.
The SDO average value TAB is adopted, and when the vehicle speed detection value exceeds a predetermined set value γ or when the vehicle is in a steering state, the actual steering torque detection value TSD and the actual steering torque differential value TSD calculated from this are used as the steering torque as they are. The detected value T8 and the steering torque differential value Φ8 are adopted as the steering torque differential value Φ8, and predetermined calculation processing is executed based on the detected value T8 and the steering torque differential value Φ8 to calculate the steering assist torque TM, and the electric motor 15 is controlled based on this. On the other hand, when the steering torque detection signal is less than a predetermined setting value α, generation of steering assist torque by the electric motor 15 is stopped.

The storage device 22d stores processing programs and predetermined setting values α and β necessary for the calculation processing of the calculation processing unit 22c.

The calculation results of the r calculation processing unit 22c are sequentially stored.

The motor drive circuit 30, as shown in FIG.
A differential amplifier 31 whose input side is supplied with a current feedback signal from a current detector 40 that detects the load current of No. 5.
, a comparison circuit 33 as a pulse width modulation circuit to which the differential amplification output thereof and the sawtooth wave signal from the sawtooth wave generation circuit 32 are supplied to the input side, and a comparison circuit 33 which is a pulse width modulation circuit to which the differential amplification output thereof and the sawtooth wave signal from the sawtooth wave generation circuit 32 are supplied. MΦ gate 34.35 to which the clockwise rotation signal S2 and counterclockwise rotation signal S3 are supplied, and any of these gates) 34.
switching transistor 36 supplied with the output of 35;
．． 37 and flywheel diodes 38 and 39 that protect these from the inductive energy accumulated in the electric motor 15, and the collectors of the switching transistors 36 and 37 are connected to the clockwise rotation terminal R and the counterclockwise rotation terminal of the electric motor 15, respectively. is connected to the motor to control the motor drive current.

Next, the operation of the above embodiment will be explained with reference to FIG. 5 showing the processing procedure in the arithmetic processing unit 22c.

The process shown in FIG. 5 is executed, for example, as a timer interrupt process for a predetermined main program at predetermined time intervals (for example, 20 m5ec).

First, in step (2), the vehicle speed detection signal from the vehicle speed sensor 16 is read, the number of pulses per unit time or the pulse interval is calculated to calculate the vehicle speed, and this is set as the vehicle speed detection value V in a predetermined storage area of the storage device 22d. temporarily memorized. Next, in step (2), the steering torque detection signal from the steering torque sensor 17 is read and temporarily stored in a predetermined storage area of the storage device 22d as the actual steering torque detection value TsD.

Next, the process proceeds to step (2), and the actual steering torque detected value T8D stored in step (2) is differentiated to calculate the actual steering torque differential value, and the value is stored as the actual steering torque differential value ↑SD in the storage device 22d. is stored in a predetermined storage area.

Next, the process moves to step (2), where the actual steering torque detection value T is determined.
The average value TAB of BD is calculated as the steering torque setting value. This average value TAB is calculated by simply averaging or moving average a plurality of past actual steering torque detection values TAB.

Next, the process moves to step (2), where the steering angle detection signal from the steering angle sensor is read, the steering direction and steering angle are determined, and these are calculated as the steering direction detection value and the steering angle detection value θ.
Each update is stored as S in a predetermined storage area of the storage device 22d.

Next, the process moves to step (2), and the steering angle detection value θS stored in step (2) is differentiated to calculate the steering speed, and the absolute value thereof is set as the steering speed detection value 19sl and stored at a predetermined value in the memory attachment 22d. Update and store in storage area.

Next, the process moves to step 2, and it is determined whether or not the detected steering torque value Ts stored in step 2 is less than a predetermined set value α. The determination in this case is that the steering system 10 has an electric motor 1.
It is determined whether or not to apply the steering assist torque according to step 5. If Ts<α, it is determined that the steering assist torque is unnecessary and the process moves to step (3).

In this step (2), from the output circuit 22b to the clutch 15
A control signal S4 with a logical value @0'' that turns off a is output to the clutch 15a, and a steering direction control signal 82,83 with a logical value @0'' is output to the motor drive circuit 30 before interrupt processing is performed. End O In this way, when the control signal S4 with the logical value "'0" is supplied to the clutch 15a, the clutch 15a is turned off and the connection between the electric motor 15 and the reduction gear 12 of the steering system 10 is interrupted. The state is released, and the steering assist torque by the electric motor 5 to the steering system 1o is not transmitted, and the wheels are steered only by the steering force of the operator steering the steering wheel.

At this time, the motor drive circuit 30 receives the steering direction control signal S2. Since S3 has the logical value "0", the game of M)
The output of 34.35 maintains a logical value of 10'', thus
Since the switching transistors 36 and 37 maintain the off state, the current supply circuit of the motor 15 is not cut off, and the motor 15 is maintained in the stopped state.

On the other hand, when the determination result in step (2) is Ts≧α, it is determined that the steering assist torque from the electric motor 15 is necessary, and the process proceeds to step (2).

In this step (2), a control signal S4 of logical value "1" is supplied to the clutch 15aK. As a result, the clutch 15a
is in the on state, the electric motor 15 and the steering system 10 are in a connected state, and a steering assist torque by the electric motor 15 is applied to the steering system 10.

Next, the process proceeds to step (3), where it is determined whether the steering is for cloth cutting or pressure cutting. At this time, when cloth cutting is being performed, the process moves to step 0, and the clockwise rotation control signal s2 from the output circuit 22b is set to a logical value of 11'', and when the pressure cutting is 9, the process moves to step ◎, where counterclockwise rotation control is performed. signal S3
Let be the logical value "'1".

Then, the process moves from step 0 or step Q to step 0, and the steering speed detection value l calculated in step (2) is
``It is determined whether or not s l is less than or equal to a predetermined set value β.This determination is to determine whether the steering system is in the steering state or in the steering state.j), l? sl>
When β, it is determined that the steering wheel is rotating and is in the steering state, and the process moves to step O.
Actual steering torque detection value 'I'sn read in step ■
and the actual steering torque differential value φSD calculated from this
are updated and stored in a predetermined storage area of the storage device 22d as a steering torque detection value Ts and a steering torque differential value Ts, respectively, and then the process moves to step 0. In step O, steering is performed based on the steering torque detection value Ts and the steering torque differential value TsK. Calculate auxiliary torque TM. This operation uses predetermined constants 1 and 2, and TM = K + X
It is calculated using the arithmetic formula: Ts Jugarasu x TS. The calculated steering assist torque TM is updated and stored in a predetermined storage area of the storage device 22d. l ”s When I≦β, it is determined that the steering wheel is not substantially rotated and is in a stable state, and the process moves to step θ, where the detected vehicle speed value V stored in step ■ becomes the preset value γ. Determine whether or not the following is true.■ If γ, proceed to step 0, and the actual steering torque detected value Ts read in step
n and the actual steering torque differential value TSD calculated by differentiating this detected value are updated and stored in a predetermined storage area of the storage device 22d as the steering torque detected value Ts and the steering torque differential value 8s, respectively, and then the process moves to the above-mentioned step O. do. ■When < γ, the process moves to step 0, and the steering torque average value TAB calculated in step ■ is used as the steering torque detected value Ts.
After updating and storing the data in a predetermined storage area of the storage device 22d, the process moves to step O. In step O, a steering assist torque target value TM is calculated based on the detected steering torque value TSK. This calculation is performed using a predetermined proportionality constant as follows: TM=KI X Ts. The calculated steering assist torque TM is stored in the storage device 22d.
is updated and stored in a predetermined storage area.

Next, the process moves to step @, and the steering assist torque value TM is determined.
Based on this, the motor drive current value IM is calculated with reference to a memory table showing the relationship between the steering assist torque value TM and the motor drive current value IM as shown in FIG. The updated information is stored in a predetermined storage area of the device 22d.

Next, the process moves to step (2), where the motor drive current value IM is determined.
e It is outputted as a motor drive control signal 81 from the output circuit 22b to the D/A converter 23.

In this way, when the motor drive control signal S1 is output,
This is converted into an analog current by the D/A converter 23, and this is supplied to the motor drive circuit 30. However, in the motor drive circuit 30, if the motor 15 is in a stopped state, a load current detector 40 detects the load current.
Since the detection signal is zero, the differential amplifier 31 outputs a relatively high level differential amplification output corresponding to the motor drive current value IM supplied from the control circuit 20. Therefore, the comparison circuit 33 outputs a pulse modulation signal with a large duty ratio (the width of the on state is larger than the width of the off state), which is output from the AND gate 34.
35. At this time, assuming that the driver is turning the steering wheel to the right (or left),
Since the clockwise rotation control signal 82 (or counterclockwise rotation control signal 83) is output from the output circuit 22b, 1. Shizuno Gate 34
An output corresponding to the pulse modulation signal is obtained from the switching transistor 34 (or 35).
5) is controlled on/off. As a result, the electric motor 15 starts to rotate clockwise (or counterclockwise), and the rotational torque is transmitted to the stub shaft 11 of the steering system 10 via the clutch 15a1 and the reduction gear mechanism 12.

When the motor 15 starts rotating, the load current detection value of the load current detector 40 increases, so the output of the differential amplifier 31 decreases, and the duty ratio of the pulse modulation signal from the comparison circuit 33 also decreases accordingly. Become. As a result, motor 1
5 is rotationally driven so as to add to the steering system 10 a steering assist torque corresponding to the steering assist torque TM output from the control circuit 2o.

As described above, when the vehicle speed detection value V exceeds the set value γ in the steering-holding state, the steering assist torque TM calculated from the steering torque detection value Ts and the steering torque differential value φS obtained by differentiating this is applied. Therefore, when the operator turns the steering wheel to shift to the steering state, the "1-stuck" feeling that occurs due to the delayed response of the steering assist torque TM due to no differentiation of the steering torque is eliminated, and good steering is achieved. You can feel it. Further, in the above embodiment, a case was explained in which a worm gear and a worm wheel were applied as a reduction gear mechanism, but the invention is not limited to this, and other reduction gears such as a bevel gear and a rack and pinion may be applied. Of course. Furthermore, the steering angle detecting means is not limited to a rotation detector such as a photocube, but may also be a steering angle sensor such as a potentiometer that generates an analog voltage depending on the steering angle. Furthermore, in the above embodiment, the case where the microcomputer 22 is applied as the control circuit 20 has been explained.
This includes, but is not limited to, logic circuits.

It can also be constructed by combining electronic circuits such as a comparison circuit and a function generator. Further, in the above embodiment, a case has been described in which the steering assist torque TM is calculated based on the calculation formula, but the invention is not limited to this, and the table may be stored in the storage device 22d in advance. The steering assist torque TM may be calculated by referring to it. Further, in the above embodiment, a case has been described in which an electric motor is used as the auxiliary force generating means, but the present invention is not limited to this, and a combination of a hydraulic actuator, a solenoid valve, etc. may be used.

〔Effect of the invention〕

As explained above, according to the present invention, the held steering state of the steering system is detected by the held steering state detection means, and when the vehicle speed detected by the vehicle speed detection means is below a predetermined set value, the steering torque detection means is activated. A holding torque consisting of the average value of the detected steering torque values or a value with high frequency components removed, and when the vehicle speed exceeds a predetermined setting value of the vehicle speed detecting means, the actual steering torque detected value of the steering torque detecting means and this actual steering torque. A value consisting of a differential value or a difference value of the actual steering torque calculated from the detected value,
Since the torque control means is configured to control the steering assist torque of the assist force generating means based on When shifting from the steering state to the steering state, the "stuck" feeling that occurs due to the delayed response of the steering assist torque due to no differentiation of the steering torque is eliminated, and a good steering feeling can be obtained. It will be done.

[Brief explanation of the drawing]

Fig. 1 is a basic configuration diagram showing an overview of the present invention, Fig. 2 is a block diagram showing an embodiment of the invention, Fig. 3 is a block diagram showing an example of a control circuit, and Fig. 4 is a block diagram showing an example of a control circuit. FIG. 5 is a flowchart showing an example of a processing procedure of the arithmetic processing unit, and FIG. 6 is a graph showing the relationship between steering assist torque TM, motor current IM, and motor rotation speed NM. In the figure, 10 is a steering system, 11 is a stub shaft, 12 is a reduction gear mechanism, 13 is a pinion gear, 14 is a rack, 15
is an electric motor, 15a is an electromagnetic clutch, 16 is a vehicle speed sensor,
17 is a steering torque sensor, 18 is a steering angle sensor, 19
20 is a control device, 20 is a control port M, 22id-v microcomputer, and 30 is a motor drive circuit. Patent Applicant: Nissan Motor Co., Ltd. Figure 1 Figure 5 Start Medium Speed Detection I Direct 1 ■Blind First Input Tribute Operation Revised Bittorque Detection 荀I Tso Begging Input Operation H Torufui Ta missing Molecule Direct 3 ■ ↑SD Calculation 77V -f-OFF Steering rail 7 average value. Steering direction white TAB calculation 5253.0FF 4 slip-P2゛1ζ output yIθS Miya is included car motor vehicle Wbi, 47t 1esl 6 calculation YES Tso<d N. Clutch○N Otl19a, YES N. -4°

Claims (1)

[Claims] an auxiliary force generating means for providing a steering assist torque in conjunction with a steering system; a steering torque means for detecting the direction and magnitude of the steering torque in the steering system; a steering angle detecting means for detecting a steering angle; and a steering holding state. a vehicle speed detection device that detects a vehicle speed; a vehicle speed of the vehicle speed device; an actual steering torque detection value of the steering torque device; a steering angle detection value of the steering angle detection device; and a vehicle speed detection device that detects a vehicle speed; A power steering device comprising: a held steering state detected by a detection means; and a torque control means for controlling the output torque of the auxiliary force generating means based on the held steering state, wherein the held steering state is detected by the held steering state detection means, and , when the vehicle speed detected by the vehicle speed detection means is below a predetermined setting value, a steering torque consisting of an average value of the actual steering torque detection value of the steering torque means or a value obtained by removing high frequency components, and the vehicle speed detection means When the vehicle speed exceeds a predetermined set value, a value consisting of an actual steering torque detection value of the steering torque detection means and a differential value or a difference value of the actual steering torque calculated from the actual steering torque detection value is used. A power steering device characterized in that the torque control means is configured to control a steering assist torque of the auxiliary force generation means.