JPH06286629A - Grip pressure sensitive type electronically controlled power steering device - Google Patents

Abstract

PURPOSE:To obtain the steering assistance state which is always optimum according to the physical power of a driver, as for a grip pressure sensitive type electronically controlled power steering device which controls the steering assistance quantity according to the grip pressure of a steering wheel. CONSTITUTION:A power steering device is equipped with an assistance quantity adjusting mechanism 1, control means 30 for controlling the assistance quantity adjusting mechanism 1, and a grip pressure sensor 34 for detecting the grip pressure of the steering wheel of an automobile, and the control means 30 controls the assistance quantity adjusting mechanism 1 so that the level of the steering force necessary in the steering of an automobile becomes smaller as the grip pressure is lower, on the basis of the grip pressure information detected by the grip pressure sensor 34.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electronically controlled power steering device for electrically controlling a steering assist amount in a steering mechanism of an automobile, and particularly to controlling the steering assist amount according to a grip pressure of a steering wheel of the automobile. , Grip pressure sensitive electronically controlled power steering device.

[0002]

2. Description of the Related Art In recent years, electronically-controlled power steering devices have become widespread in order to assist a force for operating a steering wheel (hereinafter referred to as a steering wheel) (hereinafter referred to as a steering wheel operating force or a steering force). As this electronically controlled power steering device, a hydraulic electronically controlled power steering device that assists steering by hydraulic pressure using a hydraulic cylinder mechanism is generally used. Power steering devices have also been developed.

By the way, in general, it is desired that the steering wheel can be operated more lightly at low speeds such as when entering a garage. Also, when traveling at high speed, traveling becomes unstable if the steering wheel is too light. Therefore, a vehicle speed-sensitive electronically controlled power steering device has been developed in which the steering assist amount is increased at low speeds according to the vehicle speed, and is decreased at higher speeds at medium and high speeds.

As such a vehicle speed sensitive electronically controlled power steering device, a vehicle speed sensor is provided in the vehicle so that the hydraulic pressure supplied to the electronically controlled power steering can be adjusted in a part of the hydraulic system of the hydraulic electronically controlled power steering device. By adjusting the valve and the steering reaction force, a mechanism that can be applied while adjusting the steering force can be adjusted electronically based on the vehicle speed detected by the vehicle speed sensor. There is one (this is called an electronically controlled power steering device).

For example, FIGS. 10 to 12 are all structural views showing an example of an electronically controlled power steering device, and FIG. 10 is a view showing a longitudinal section of an input shaft portion and a pinion portion together with a hydraulic cylinder for electronically controlled power steering. FIG. 11 is a cross-sectional view of the input shaft portion and is a cross-sectional view taken along the line AA of FIG.
11 is a configuration diagram showing a vertical cross section of a hydraulic control valve arranged in parallel with an input shaft together with a reaction force plunger, the hydraulic control valve portion is a sectional view taken along line CC of FIG. 11, and the reaction force plunger portion is shown in FIG. It is a BB sectional view.

In FIGS. 10 to 12, reference numeral 11 is an input shaft that receives a steering force from a steering wheel (handle) (not shown), and is rotatably mounted inside a casing 25. A pinion gear 12 is provided at the lower end of the input shaft via a bush or the like (not shown). A torsion bar 15 is provided inside the input shaft 11, and the torsion bar 15 has its upper end at the input shaft 11.
Is connected to the input shaft 11 via a pin or the like so as to rotate integrally, and its lower end is not restrained with respect to the input shaft 11.

The pinion gear 12 is serrated with the lower end of the torsion bar 15, and the steering force input to the input shaft 11 is applied to the torsion bar 1.
It is adapted to be transmitted to the pinion gear 12 via 5. The pinion gear 12 meshes with the rack 13, and the steering force is transmitted to the rack 13 via the pinion gear 12 to drive the rack 13 in the axial direction to steer the wheels.

Reference numeral 14 denotes a hydraulic cylinder for electronically controlled power steering (power steering). The hydraulic cylinder 14 includes a cylinder 14A installed on a member on the vehicle body side,
A piston 14B provided in the middle of the rack 13 and moving axially in the cylinder portion 14A together with the rack 13 is provided. Inside the cylinder 14A, the piston 14B divides the oil chamber 14C into left and right portions to form oil chambers 14C and 14D. ing.

Further, 16 is a rotary valve for driving the hydraulic cylinder 14, and depending on the opening / closing of the rotary valve 16, the left and right oil chambers 14C, 1C of the hydraulic cylinder 14 are opened.
The hydraulic oil is supplied to or discharged from the 4D to apply the steering assist force to the rack 13. The rotary valve 16 is interposed between the input shaft 11 side and the pinion gear 12 side, and is opened / closed according to the phase difference between the input shaft 11 and the pinion gear 12. That is, the input shaft 1
When a steering force is input to the input shaft 11, the input shaft 11 is rigid and hardly twists.
5 transmits the steering force to the pinion gear 12 while causing twisting, so that the pinion gear 12 moves the input shaft 1
A phase difference is generated on the steering side with respect to 1. The rotary valve 16 is opened / closed so that a required amount of steering assist force (also referred to as steering assist amount) is generated in the steering direction according to the phase difference.

A reaction force plunger 17 is provided on the outer periphery of the lower portion of the input shaft 11 to increase the steering force (that is, steering response) by applying a steering reaction force during steering. As shown in FIG. 12, a plurality of the reaction force plungers 17 are provided so as to surround the outer circumference of the input shaft 11, and receive the hydraulic pressure supplied through the control of the hydraulic pressure control valve 18 in the chamber 17A at the back thereof. As a result, it is possible to perform the same control as that of restraining the input shaft 11 according to the hydraulic pressure to give a steering reaction force to reduce the steering assist amount. That is, the steering reaction force adjusting mechanism 1 including the reaction force plunger 17 and the hydraulic control valve 18 corresponds to an assist amount adjusting mechanism.
The chamber 17A communicates with the oil reservoir 24 side via the return orifice 22.

As shown in FIG. 12, the hydraulic control valve 18 is provided on the side of the input shaft 11 in the casing 25 in parallel with it, and has a plunger 18A capable of sliding up and down in the casing 25, and this plunger 18A. It has a solenoid 19 for applying an upward axial force to the plunger 18A and a spring 20 for urging the plunger 18A downward.

The plunger 18A includes an oil reservoir 2
4, the oil passages 18B and 18C, the annular oil passage 18D that can communicate with the oil pump 23, the annular oil passage 18E that can communicate with the chamber 17A of the reaction force plunger 17, and the annular oil passages 18D and 18E that communicate with each other. The oil passage 18F is provided. That is, the chamber 1 of the reaction force plunger 17
7A includes annular oil passage 18D to oil passage 18F and annular oil passage 1
High-pressure hydraulic oil from the oil pump 23 can be supplied through 8E.

Then, for example, at the time of stationary steering or steering at low speed traveling, the maximum current is applied to the solenoid 19. As a result, the plunger 18A rises most and the annular oil passage 18D is no longer in communication with the oil pump 23,
Oil is not supplied to the chamber 17A of the reaction force plunger 17, and the reaction force plunger 17 does not restrain the input shaft 11, so that the steering can be performed lightly.

In addition, for example, when the vehicle travels at medium and high speeds, the current supplied to the solenoid 19 is decreased as the vehicle speed increases. Then, when the handle is neutral, the plunger 18
The axial force of A decreases as the current decreases, and accordingly the plunger 18A descends so that the annular oil passage 18D communicates with the oil pump 23.
The oil is supplied to the chamber 17A.

In this state, the reaction force plunger 17 restrains the input shaft 11 so that the handle is kept neutral. When the steering wheel is slightly steered in this neutral state, the oil pump output tries to rise, but this discharge pressure is hardly controlled by the hydraulic control valve 18 and acts on the chamber 17A of the reaction force plunger 17. . Therefore, in the vicinity of the neutral state of the steering wheel, the steering force is increased, the neutral response of the steering wheel can be sufficiently obtained, and the sense of steering stability in the neutral state is increased.

[0016] When steering during this medium to high speed traveling, within the normal steering range, the oil pump output increases in response to steering of the steering wheel (in response to an increase in steering force), and steering assist is increased. Acts like. On the other hand, while the discharge pressure of the oil pump is controlled by the hydraulic control valve 18,
It acts on the chamber 17A of the reaction force plunger 17. Therefore, the reaction force plunger 17 acts to restrain the input shaft 11 and increase the steering response (steering force).

As a result, the steering force at the time of steering at medium and high speeds is increased by the amount of the reaction force plunger 17 acting as compared with that at the time of stationary steering and steering at low speeds. That is, the steering response is increased, and a stable steering feeling is obtained. In particular, by decreasing the current applied to the solenoid 19 as the vehicle speed increases, the steering assist decreases and the steering force (steering response) increases as the vehicle speed increases, resulting in a more stable steering feeling. Is obtained.

As described above, by adjusting the current applied to the solenoid 19, the steering assist characteristic can be controlled. For example, as shown in FIG. 12, in addition to the vehicle speed information from the vehicle speed sensor 31, an EPS (electronically controlled power steering) is provided. Based on the mode setting information from the mode changeover switch 32, the engine speed signal from the engine speed sensor 33, etc., the control unit (control means) 30 sets the amount of current to be supplied to the solenoid 19, and the solenoid 19 is turned on. Have control.

In other words, the EPS mode changeover switch 32 can set the normal mode and the sports mode in which the control for increasing the steering force is started from a speed lower than the normal mode, and the control unit 30 sets these modes. According to the mode, the assist characteristic of the electronically controlled power steering is controlled. For example,
As shown in FIG. 13, when the sport mode is set, the assist amount is controlled to decrease based on the vehicle speed information so that the steering force increases abruptly as the speed increases from a relatively low speed region. When set to, the assist amount is controlled to decrease based on the vehicle speed information so that the steering force gradually increases as the speed increases after the speed relatively increases.

For this reason, the amount of current applied to the solenoid 19 is set as shown in FIG. That is, in the sport mode, the solenoid current decreases abruptly as the speed increases from the relatively low speed region, and in the normal mode, the solenoid current increases to the relatively high speed region. The maximum state is maintained, and thereafter, the solenoid current gradually decreases as the speed increases.

The correlation characteristic between the steering force and the output hydraulic pressure is
As shown in FIG. 15, as the vehicle speed increases,
The reaction force applied by the reaction force plunger 17 increases,
In the normal steering force range, the output pressure of the pump that determines the steering assist amount is lower than that at low speed. It should be noted that this electronically controlled power steering device detects an abnormality in the detection system or the like from the vehicle speed information, the engine rotation signal, etc., and at this time, the solenoid 19 is turned off to perform fail-safe control. ing.

[0022]

By the way, it is not always sufficient to control the steering assist force in accordance with the vehicle speed, and the required assist amount varies depending on the physical strength of the driver. There is also a demand for assist amount control in consideration of this point. For example, in general, the older the driver is, the lower the physical strength level is, and the female driver is weaker and the physical strength level is lower than the male driver. Such a driver with a low level of physical strength tends to have a burden on the steering operation, and thus the steering assist amount should be increased. In addition, even if the driver is the same, he / she wants more steering assistance when he / she is tired.

The present invention was devised in view of the above-mentioned problems, and provides a grip pressure sensitive electronically controlled power steering device capable of always obtaining an optimum steering assist state in accordance with the physical condition of the driver. The purpose is to

[0024]

Therefore, the grip pressure sensitive electronically controlled power steering device according to the present invention is an electronically controlled power steering device for assisting steering of a vehicle, and the assist amount is increased or decreased. An electronically controlled power steering device comprising an adjustable assist amount adjusting mechanism and a control means for controlling the assist amount adjusting mechanism, comprising: a grip pressure sensor for detecting a grip pressure of a steering wheel of the automobile; The means controls the assist amount adjusting mechanism so that the lower the grip pressure is, the lower the level of the steering force required for steering the vehicle is based on the grip pressure information detected by the grip pressure sensor. It is characterized by being configured.

The grip pressure sensitive electronically controlled power steering device according to the present invention is an electronically controlled power steering device for assisting steering of an automobile, and an assist amount adjusting mechanism capable of increasing or decreasing the assist amount. And a control means for controlling the assist amount adjusting mechanism, in an electronically controlled power steering device, a vehicle speed sensor for detecting a vehicle speed of the vehicle, and a grip pressure sensor for detecting a grip pressure of a steering wheel of the vehicle. Based on the vehicle speed information detected by the vehicle speed sensor and the grip pressure information detected by the grip pressure sensor, the control means steers the vehicle as the vehicle speed becomes lower and the grip pressure becomes lower. It is configured to control the assist amount adjusting mechanism so that the level of steering force required at the time becomes small. It is characterized in that there.

According to a third aspect of the present invention, the grip pressure sensor is provided on the grip surface of the steering wheel and has a pressure-sensitive conductive rubber whose electric resistance value changes according to the amount of pressure received, and the pressure-sensitive conductive rubber. A resistance measuring circuit provided to measure the electric resistance value of the conductive rubber may be provided, and the electric resistance corresponding amount that can be output from the resistance measuring circuit may be the grip pressure corresponding amount.

[0027]

In the grip pressure-sensitive electronically controlled power steering device according to the present invention as set forth in claim 1, the control means electrically controls the assist amount adjusting mechanism, and the assist amount adjusting mechanism adjusts the assist amount to increase or decrease. To be done. At this time, the control means, based on the grip pressure information of the steering wheel detected by the grip pressure sensor, lowers the grip pressure so that the level of the steering force required for steering the vehicle decreases. Controls the quantity adjustment mechanism.

In the grip pressure sensitive electronically controlled power steering device according to the present invention, the control means electrically controls the assist amount adjusting mechanism, and the assist amount adjusting mechanism increases or decreases the assist amount. To be done. At this time, the control means, based on the vehicle speed information of the vehicle detected by the vehicle speed sensor and the gripping pressure information of the steering wheel detected by the grip pressure sensor, the lower the vehicle speed and the lower the grip pressure, the more the vehicle. The assist amount adjusting mechanism is controlled so that the level of the steering force required for steering is reduced.

According to the third aspect of the invention, when the grip pressure sensor is configured, when the grip surface of the steering wheel is gripped, the pressure-sensitive conductive rubber changes its electric resistance value according to the amount of pressure received. Let When an electric resistance corresponding amount is output from a resistance measuring circuit provided to measure the electric resistance value of the pressure-sensitive conductive rubber, the electric resistance corresponding amount corresponds to a grip pressure corresponding amount, that is, a grip pressure. The amount can be used for the assist amount control described above.

[0030]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A grip pressure sensitive electronically controlled power steering device as an embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic configuration diagram thereof, and FIG. 2 is a steering force for each selection mode thereof. FIG. 3 is a diagram showing characteristics, FIG. 3 is a diagram showing characteristics of a control amount (here, control current) of the assist amount adjusting mechanism for each selection mode, and FIG. 4 is a schematic diagram showing a main part of a grip pressure sensor of the steering wheel. 7 is a schematic sectional view showing the grip pressure sensor, FIG. 6 is a view showing the principle of the grip pressure sensor, and FIG.
FIG. 8 is a diagram showing a grip pressure characteristic, FIG. 8 is a diagram showing a steering force characteristic with respect to the grip pressure, and FIG. 9 is a diagram showing a relationship between the grip pressure and a contact area.

The mechanical portion (hardware structure) of this grip pressure sensitive electronically controlled power steering device is constructed in substantially the same manner as that of the above-mentioned conventional example (see FIGS. 10 to 12), and therefore will be briefly described. . That is, FIG. 1 and FIG.
As shown by 0 and 11, a torsion bar 15 is connected to the inside of the input shaft 11 so that the upper end thereof rotates integrally with the input shaft 11, and the lower end of the torsion bar 15 is restrained with respect to the input shaft 11. Not not.

The pinion gear 12 is serrated with the lower end of the torsion bar 15, and the steering force input to the input shaft 11 is applied to the torsion bar 1.
It is adapted to be transmitted to the pinion gear 12 via 5. The pinion gear 12 meshes with the rack 13, and the steering force is transmitted to the rack 13 via the pinion gear 12 to drive the rack 13 in the axial direction to steer the wheels.

Hydraulic cylinder 1 provided on the rack 13
Reference numeral 4 denotes a cylinder 14A installed on a member on the vehicle body side, and a piston 14B which is provided in the middle of the rack 13 and moves axially in the cylinder portion 14A together with the rack 13, and the cylinder 14A has the piston 14B. The oil chambers 14C and 14D are partitioned by 14B on the left and right sides.

Further, a rotary valve 16 is interposed between the input shaft 11 side and the pinion gear 12 side, and this rotary valve 16 opens and closes according to the phase difference between the input shaft 11 and the pinion gear 12. , Accordingly, the oil chambers 14 on the left and right of the hydraulic cylinder 14
The hydraulic oil is supplied to or discharged from C and 14D, and the steering assist force is applied to the rack 13.

The input shaft 11 comprises a reaction force plunger 17, a hydraulic control valve 18, etc.
A steering reaction force adjusting mechanism 1 as an assist amount adjusting mechanism is provided. That is, a reaction force plunger 17 is provided on the outer periphery of the lower portion of the input shaft 11 to increase the steering force (that is, steering response) by applying a steering reaction force during steering. A plurality of the reaction force plungers 17 are provided so as to surround the outer circumference of the input shaft 11, and by receiving the hydraulic pressure supplied through the control of the hydraulic pressure control valve 18 in the chamber 17A at the back thereof, the reaction force plungers 17 are responsive to the hydraulic pressure. The input shaft 11 is restrained to apply a steering reaction force. The chamber 17A communicates with the oil reservoir 24 side via the return orifice 22.

The hydraulic control valve 18 is provided in a side portion of the input shaft 11 in the casing 25 in parallel therewith, and has a plunger 18A capable of sliding up and down in the casing 25 and an upward shaft of the plunger 18A. It has a solenoid 19 for giving force and a spring 20 for urging the plunger 18A downward. The plunger 18A has an oil passage 18 communicating with the oil reservoir 24.
B, 18C and annular oil passage 1 that can communicate with the oil pump 23
8D, an annular oil passage 18E that can communicate with the chamber 17A of the reaction force plunger 17, and these annular oil passages 18D and 18E.
And an oil passage 18F communicating with each other. That is, the chamber 17A of the reaction force plunger 17 can be supplied with high-pressure hydraulic oil from the oil pump 23 through the annular oil passage 18D, the oil passage 18F, and the annular oil passage 18E.

As shown in FIG. 1, such a hydraulic control valve 18 has a vehicle speed information from a vehicle speed sensor 31, a mode selection signal from an EPS mode changeover switch 32, and a steering wheel (handle) from a grip pressure sensor 34.
The control unit (control means) 30 sets the amount of current to be supplied to the solenoid 19 on the basis of the grip pressure information of the steering wheel, the generated torque information of the steering wheel from the steering wheel generated torque sensor 35, and controls the solenoid 19. .

That is, in the control unit 30,
When the normal running mode is selected by the EPS mode changeover switch 32, the steering reaction force is controlled so that the steering force characteristics shown by the curves n, n1 and n2 in FIG.
When the sports running mode is selected by the mode changeover switch 32, the steering reaction force is controlled so that the steering force characteristics shown by the curves s, s1, and s2 in FIG. 2 are obtained. It should be noted that this diagram of the steering force characteristic shows the magnitude of the steering force required when the slalom traveling is performed within a predetermined steering angle range in correspondence with the vehicle speed.

As shown in the figure, in both the normal traveling mode and the sports traveling mode, the steering force is small at low vehicle speeds, but the steering force increases as the vehicle speed increases. In the sports driving mode, the steering force is larger than that in the normal traveling mode from a state where the vehicle speed is relatively low, and a relatively large steering force is required in a wide traveling speed range except when the vehicle speed is low. Is the same as the conventional example.

However, in this device, even if the sport driving mode or the normal driving mode is selected, the steering force characteristic is not determined only by this, and further, the steering force is determined according to the physical strength level of the driver based on the grip pressure information. The characteristics are determined. In other words, if the driver's physical strength is sufficient and the steering operation does not become a burden, the steering assist amount may be reduced, or rather, the steering assist amount is suppressed so that the steering response of the steering wheel can be obtained, and the steering assist amount is reduced during steering. Since a relatively large steering force is required, and conversely, if the driver's physical strength is low, the steering operation becomes a burden, the steering assist amount is increased so that the steering can be performed with a relatively small steering force.

The physical strength mentioned here may be considered as the arm strength required for steering, but this physical strength (that is, the arm strength)
Since it is difficult to measure itself, the driver's physical strength is estimated from this grip pressure by focusing on the relationship between the grip pressure for gripping the handle and the physical strength (arm strength). That is, as shown in FIG. 7, the grip pressure for gripping the handle is
Generally, the steering force increases almost in proportion to the steering force given by the driver through the steering wheel (that is, the torque generated from the steering wheel). The pressure tends to be strong.

That is, in FIG. 7, the grip pressure is classified into three types of layers, that is, the young male layer, the middle-aged male layer, the female layer, and the elderly layer, and the respective grip pressure characteristics are different. It is displayed in the area. In general, young men have the highest physical fitness, middle-aged men have physical fitness, and females and older people have low physical fitness. It turns out that there is a strong tendency.

Therefore, in the control unit 30,
The physical strength level of the driver is estimated based on the grip pressure of the driver and the torque generated from the steering wheel. This estimation is performed by obtaining each data of the grip pressure and the generated torque at an appropriate cycle, and obtaining the most recent required number of sampling data. Therefore, the physical strength level is estimated based on the correlation between the grip pressure and the generated torque. Therefore, even if the driver is replaced or the same driver is tired and the physical strength is lowered, the current physical strength state of the driver is appropriately estimated after an appropriate sampling time.

Then, in the control unit 30,
Under the setting of the EPS mode changeover switch 32, the steering force state, that is, the degree of the assist amount of the power steering is set based on the estimated physical strength level and the detected vehicle speed. For example, when the EPS mode changeover switch 32 is set to the normal running mode, if the physical strength level is determined to be medium, the physical strength level is high so that the steering force characteristic shown by the curve n in FIG. 2 is obtained. If it is determined that the steering force is relatively large as shown by the curve n1 in FIG.
If it is determined that the physical strength level is low, reaction force control is performed so that the steering force becomes relatively small as shown by the curve n2 in FIG.
Further, when the EPS mode changeover switch 32 is set to the sports running mode, the steering force characteristic shown by the curve s in FIG. 2 can be obtained when the physical strength level is medium.
When the physical strength level is high, the steering force becomes relatively large as shown by the curve s1 in FIG. 2, and when the physical strength level is low, the steering force is relatively small as shown by the curve s2. The reaction force is controlled so that the following characteristics can be obtained.

Therefore, the amount of current supplied to the solenoid 19 has the characteristics shown in FIG. 3, and is set from the physical strength level and the vehicle speed under the setting of the EPS mode changeover switch 32. The steering wheel generated torque sensor 35 that detects the generated torque from the steering wheel can be configured by, for example, a strain gauge that detects the twisted state of the torsion bar 15. Further, the grip pressure sensor 34 that detects the grip pressure of the driver can be configured using, for example, pressure-sensitive conductive rubber as shown in FIGS.

That is, as shown in FIG. 4, the handle 2
Is the pressure-sensitive conductive rubber 2B on the outer circumference of the metal hollow pipe 2A.
And the metal foil 2 on the outer periphery of the pressure-sensitive conductive rubber 2B.
After covering C, the outer periphery is covered with a skin 2D. The pressure-sensitive conductive rubber 2B is one in which the conductive particles 4 are contained in the rubber 3, is a conductive pair as a whole, and has a characteristic that the resistance changes according to the applied pressure.

The hollow pipe 2A and the pressure-sensitive conductive rubber 2
The conductive system in which B and the metal foil 2C are laminated is incorporated in the grip pressure detection circuit 5 as shown in FIG. Thereby, as shown in FIG. 6, between the two electrodes of the hollow pipe 2A and the metal foil 2C, the resistance change of the pressure-sensitive conductive rubber 2B according to the pressurization state can be detected by, for example, the voltage change between the electrodes. It has become.

In FIG. 5, reference numeral 6 is a battery, but the electric wire 5A from the hollow pipe 2A side to the battery 6 is
For example, it can be guided from the inside of the hollow pipe 2A to the inside of the engine room (not shown) in which the battery 6 is installed via the steering spoke portion (not shown) and the steering column portion (not shown), and the battery 6 can be guided from the metal foil 2C side. The electric wire 5B can also be guided into the engine room (not shown) via, for example, a steering spoke portion (not shown) or a steering column portion (not shown).

Further, the information corresponding to the grip pressure such as the voltage change between the electrodes thus detected is, as shown in FIG. 1, the control unit 3 as the grip pressure information.
It is supposed to be sent to 0. The grip pressure sensor 34 utilizes that the resistance of the pressure-sensitive conductive rubber 2B changes according to the pressurization state, as shown in FIG.
The resistance of the pressure-sensitive conductive rubber 2B actually affects the grip area (contact area). That is, as the grip area increases, the resistance of the pressure-sensitive conductive rubber 2B also increases. However, as shown in FIG. 9, this grip area is generally
The larger the grip pressure, the larger the grip area. Therefore, the increase / decrease tendency of the resistance of the pressure-sensitive conductive rubber 2B corresponds to the increase / decrease of the grip pressure, and the grip pressure can be detected from the resistance of the pressure-sensitive conductive rubber 2B while considering the grip area.

Since the grip pressure sensitive electronically controlled power steering device as one embodiment of the present invention is constructed as described above, the setting signal of the EPS mode changeover switch 32 and the vehicle speed are set while the vehicle is in operation. The detection information from the sensor 31, the grip pressure sensor 34, and the handle generation torque sensor 35 are sent to the control unit 30 at an appropriate cycle.

Then, in the control unit 30,
From the latest required number of sampling data, estimate the physical strength level based on the correlation between the grip pressure and the generated torque,
Under the setting of the EPS mode changeover switch 32, the steering force state, that is, the assist amount of the power steering (that is, the steering reaction force in this case) is calculated from the thus estimated physical strength level and the detected vehicle speed. The amount of current applied to the solenoid 19 is controlled so that it can be obtained.

For example, when the EPS mode changeover switch 32 is set to the normal running mode, the current of the solenoid 19 is controlled by the characteristics shown by characteristic lines n, n1 and n2 in FIG. Is set to the sports driving mode, the curves s, s1, and
The current of the solenoid 19 is controlled with the characteristic shown by s2.

In particular, if the driver's physical strength level is judged to be medium, the current of the solenoid 19 is controlled with the characteristics shown by the curves n and s in FIG. 3, and if the driver's physical strength level is judged to be high. If the current of the solenoid 19 is controlled with the characteristics shown by the lines n1 and s1 in FIG. 3 and it is determined that the physical strength level of the driver is low, the solenoid 19 has the characteristics shown by the lines n1 and s1 in FIG. Control the current.

As a result, the EPS mode changeover switch 3
Depending on the physical strength level of the driver for each of the 2 mode settings,
If the driver's physical fitness level is medium, the curve n,
If the physical strength level of the driver is high as shown by s, the characteristics shown by curves n1 and s1 in FIG.
When the driver's physical strength level is low, curves n2 and s2 are shown in FIG.
The steering force is adjusted to the characteristic shown by.

Therefore, the optimum steering assist state can always be obtained according to the physical condition of the driver. For example, for drivers with low physical strength such as female drivers and elderly drivers,
Since a large steering assist amount is given, steering can be performed with a small steering force, and the burden of steering operation is reduced. Further, even the same driver can give a larger steering assist amount as he / she is fatigued, and the burden of steering operation at the time of fatigue is reduced. On the other hand, in the case of a driver having sufficient physical strength, it is possible to require a large steering force so that the burden of the steering operation does not become excessive, so that the steering operation feeling can be reliably obtained and the steering stability of the steering wheel is improved. it can.

In particular, the physical condition of the driver is estimated by the grip pressure of the steering wheel, but there is a sufficient correspondence between the grip pressure and the physical condition of the driver, and
Since the grip pressure can be easily measured by using the pressure-sensitive conductive rubber, the physical condition of the driver can be reliably estimated. Further, the pressure-sensitive conductive rubber can be mounted so as not to significantly affect the feeling of use of the handle, and the grip pressure detection circuit can be equipped so as not to interfere with the handle operation. Therefore, the grip pressure can be measured while ensuring the operability of the handle.

In this embodiment, the steering force characteristic corresponding to the target vehicle speed is set in three stages of high, medium and low levels of physical strength, but the level of physical strength is limited to 3 levels. Instead, it may be divided into only two stages, high and low, or more than three stages. Also, FIG.
The characteristic diagram shown in is an example, and the characteristic is not limited to this as long as the steering force can be increased or decreased according to the level of physical strength as shown in the embodiment.

For example, FIG. 8 is a diagram showing another example of setting the optimum steering feeling characteristic according to the grip pressure. In the figure, the broken line shows the boundary value of the mode division according to the vehicle speed corresponding characteristic of the grip pressure Gp when a predetermined steering force torque is generated, and the dashed line shows the optimum steering force characteristic corresponding to this mode division. Here, a <Gp ≦ b, b <Gp ≦ c, c <Gp ≦ in the order of higher grip pressure Gp, that is, in the order of higher physical strength.
It is classified into four modes of d and d <Gp ≦ e. Then, in the mode of a <Gp ≦ b, the steering force characteristic is as shown by the chain line α, in the mode of b <Gp ≦ c, the steering force characteristic is as shown by the chain line β, and in the mode of c <Gp ≦ d. ,
The steering force characteristic is as shown by the chain line γ, and the steering force characteristic is as shown by the chain line δ in the mode of d <Gp ≦ e.

Further, in the figure, the solid line shows a conventional electronically controlled power steering device (EPS), a general power steering device without conventional electronic control (with P / S), a steering device without a power steering device (without P / S). ) Shows each steering force characteristic in correspondence with the vehicle speed. As shown in the figure, the steering force is set according to the level of the grip pressure Gp, that is, the level of the physical strength, and the same operation and effect as those of the embodiment can be obtained. Since it is subdivided into stages, more appropriate steering force control can be performed. The chain lines α, β, γ and δ are all extremely schematic characteristic diagrams showing the tendency of the steering force characteristic.
Actually, as in the steering force characteristics of the conventional electronically controlled power steering device, the steering force characteristics gradually increase with respect to the vehicle speed in the low vehicle speed range.
It is conceivable to set it so that it has the increasing characteristics shown by γ and δ.

Further, in the present embodiment, the normal mode and the sport mode are selected by the EPS mode changeover switch 32, but the EPS mode may be set to various modes. ,Of course,
It may be set to one without EPS mode switching. Further, although not described in the present embodiment, the grip pressure sensitive electronically controlled power steering device detects an abnormality such as a detection system from the vehicle speed information and the engine rotation signal,
It is also possible to add a configuration for performing fail-safe control by turning off the solenoid 19 or the like when an abnormality is detected.

Further, in the present embodiment, the steering reaction force adjusting mechanism 1 is provided as the assist amount adjusting mechanism and the assist amount of the power steering is adjusted by adjusting the steering reaction force. In an electrohydraulic power steering device or the like for generating the, the assist hydraulic pressure itself can be finely adjusted, so an assist amount adjusting mechanism that adjusts the assist hydraulic pressure itself by adjusting the assist hydraulic pressure is also conceivable. Further, the grip pressure sensitive electronically controlled power steering device may be applied to an electric power steering device that assists steering with an electric motor.

[0062]

As described above in detail, according to the grip pressure sensitive electronically controlled power steering device of the present invention as defined in claim 1, the electronically controlled power steering device for assisting steering of an automobile is provided. With an assist amount adjusting mechanism capable of increasing and decreasing the adjustment amount, and a control means for controlling the assist amount adjusting mechanism, in an electronically controlled power steering device, a grip pressure sensor for detecting a grip pressure of a steering wheel of the automobile is provided. Based on the grip pressure information detected by the grip pressure sensor, the control means controls the assist amount adjusting mechanism such that the lower the grip pressure, the smaller the level of the steering force required for steering the vehicle. With this configuration, it is possible to always obtain the optimum steering assist state according to the physical condition of the driver. That. For example, a driver with low physical strength can perform steering with a small steering force, and the burden of steering operation is reduced. Further, even the same driver can give a larger steering assist amount as he / she is fatigued, and the burden of steering operation at the time of fatigue is reduced.
On the other hand, in the case of a driver having sufficient physical strength, it is possible to require a large steering force so that the burden of the steering operation does not become excessive, so that the steering operation feeling can be reliably obtained and the steering stability of the steering wheel is improved. it can.

According to the grip pressure sensitive electronically controlled power steering device of the present invention as defined in claim 2, the electronically controlled power steering device assists the steering of the automobile, and the assist amount for increasing or decreasing the assist amount can be adjusted. In an electronically controlled power steering device having an adjusting mechanism and a control means for controlling the assist amount adjusting mechanism, a vehicle speed sensor for detecting a vehicle speed of the automobile and a grip pressure for detecting a grip pressure of a steering wheel of the automobile. The vehicle is equipped with a sensor, and the control means has a lower vehicle speed and a lower grip pressure based on the vehicle speed information detected by the vehicle speed sensor and the grip pressure information detected by the grip pressure sensor. The assist amount adjusting mechanism is controlled so that the level of the steering force required for steering the vehicle is reduced. By being claim 1
Similar to the described device, the optimum steering assist state is always obtained according to the physical strength state of the driver, and in particular, since the level of the steering force is adjusted based on the vehicle speed state as well as the physical strength state of the driver, an appropriate steering operation is always performed. The assist state is realized.

According to a third aspect of the present invention, the grip pressure sensor is provided on the grip surface of the steering wheel, and the pressure sensitive conductive rubber whose electric resistance value changes according to the amount of pressure received, and the pressure sensitive conductive rubber. A resistance measuring circuit provided to measure the electric resistance value of the conductive rubber is provided, and the electric resistance corresponding amount that can be output from the resistance measuring circuit is configured to be the grip pressure corresponding amount. The grip pressure can be reliably detected.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram showing a grip pressure-sensitive electronically controlled power steering device as an embodiment of the present invention.

FIG. 2 is a diagram showing steering force characteristics in each selection mode in the grip pressure sensitive electronically controlled power steering device as one embodiment of the present invention.

FIG. 3 is a diagram showing a control amount (here, control current) characteristic of an assist amount adjusting mechanism for each selection mode in a grip pressure sensitive electronically controlled power steering device as one embodiment of the present invention.

FIG. 4 is a schematic cross-sectional view showing an essential part of a grip pressure sensor of a steering wheel of a grip pressure sensitive electronically controlled power steering device as an embodiment of the present invention.

FIG. 5 is a schematic configuration diagram showing a grip pressure sensor of a grip pressure sensitive electronically controlled power steering device as an embodiment of the present invention.

FIG. 6 is a diagram showing the principle of a grip pressure sensor of a grip pressure sensitive electronically controlled power steering device as an embodiment of the present invention.

FIG. 7 is a diagram illustrating the principle of a grip pressure sensitive electronically controlled power steering device as an embodiment of the present invention, and is a diagram showing general characteristics of grip pressure.

FIG. 8 is a diagram showing a steering force characteristic with respect to a grip pressure of a grip pressure sensitive electronically controlled power steering device as an embodiment of the present invention.

FIG. 9 is a diagram for explaining the principle of a grip pressure sensitive electronically controlled power steering device as an embodiment of the present invention, and is a diagram showing a specific example of the relationship between grip pressure and contact area.

FIG. 10 is a view showing a vertical cross section of an input shaft portion and a pinion portion in a conventional electronically controlled power steering device together with a power steering hydraulic cylinder.

FIG. 11 is a cross-sectional view of an input shaft portion of a conventional electronically controlled power steering device, and FIG.
It is an AA sectional view of No. 0.

FIG. 12 is a configuration diagram showing a vertical cross section of a hydraulic control valve provided in parallel with an input shaft in a conventional electronically controlled power steering device together with a reaction force plunger;
The hydraulic control valve portion is a sectional view taken along line CC of FIG. 11, and the reaction force plunger portion is a sectional view taken along line BB of FIG.

FIG. 13 is a diagram showing steering force characteristics in each selection mode in a conventional electronically controlled power steering device.

FIG. 14 is a diagram showing a control amount (here, control current) characteristic of the assist amount adjusting mechanism for each selection mode in the conventional electronically controlled power steering device.

FIG. 15 is a diagram showing a characteristic of an assist output hydraulic pressure related to a steering force in a conventional electronically controlled power steering device.

[Explanation of symbols]

 1 Steering reaction force adjusting mechanism as an assist amount adjusting mechanism 2 Handle (steering wheel) 2A Hollow pipe 2B Pressure-sensitive conductive rubber 2C Metal foil 2D Skin 3 Rubber 4 Conductive particles 5 Grip pressure detection circuit 5A, 5B Electric wire 6 Battery 11 Input shaft 12 Pinion Gear 13 Rack 14 Hydraulic Cylinder 14A Cylinder 14B Piston 14C, 14D Oil Chamber 15 Torsion Bar 16 Rotary Valve 17 Reaction Force Plunger 17A Chamber 18 Hydraulic Control Valve 18A Plunger 18B, 18C Oil Path 18D, 18E Annular Oil Path 18F Solenoid Oil Path 20 Spring 22 Return Orifice 24 Oil Reservoir 25 Casing 30 Control Unit (Control Means) 31 Vehicle Speed Sensor 32 EPS Mode Changeover Switch 34 Green Flop pressure sensor 35 steering wheel torque sensor

Claims (3)

[Claims] 1. An electronic control power steering device for assisting steering of a vehicle, comprising: an assist amount adjusting mechanism capable of increasing or decreasing the assist amount; and a control means for controlling the assist amount adjusting mechanism. In the power steering device, a grip pressure sensor for detecting the grip pressure of the steering wheel of the automobile is provided, and the control means is based on the grip pressure information detected by the grip pressure sensor. A grip pressure sensitive electronically controlled power steering device, characterized in that the assist amount adjusting mechanism is controlled so that the level of steering force required during steering becomes small. 2. An electronically controlled power steering device for assisting steering of an automobile, comprising: an assist amount adjusting mechanism capable of increasing or decreasing an assist amount; and a control means for controlling the assist amount adjusting mechanism. In the power steering device, a vehicle speed sensor for detecting a vehicle speed of the vehicle and a grip pressure sensor for detecting a grip pressure of a steering wheel of the vehicle are provided, and the control means includes the vehicle speed information detected by the vehicle speed sensor and the vehicle speed information. Based on the grip pressure information detected by the grip pressure sensor, the assist amount adjusting mechanism is set so that the lower the vehicle speed and the lower the grip pressure, the smaller the level of the steering force required for steering the vehicle. A grip pressure-sensitive electronically controlled power steering device, characterized in that it is configured to control. 3. The pressure sensitive conductive rubber, wherein the grip pressure sensor is disposed on the grip surface of the steering wheel, and whose electric resistance value changes according to the amount of pressure received, and the electric resistance value of the pressure sensitive conductive rubber. 3. A resistance measuring circuit provided to do so, and an electric resistance corresponding amount that can be output from the resistance measuring circuit is set as a grip pressure corresponding amount. Grip pressure sensitive electronically controlled power steering device.