JP2738169B2 - Vehicle steering system - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a steering apparatus for a vehicle, and more particularly to a steering apparatus which can be applied to a vehicle equipped with a power steering system and a vehicle not equipped with a power steering system to improve the steering force characteristics.

[0002]

2. Description of the Related Art In a vehicle steering system, a steering wheel transmits a steering force to a wheel via a steering system to perform steering. In the case of a vehicle with a power steering mechanism, in addition to the above, power steering is performed using hydraulic pressure or the like to make steering easier. A power steering system is configured by incorporating a control valve that generates assist hydraulic pressure in accordance with an operation amount of a steering wheel, a hydraulic cylinder operated by the control valve, and the like into a steering mechanism in a basic hydraulic operation example. be able to.

[0003]

In such a steering device, friction exists in the steering system.
If the friction at the time of rotation of the steering shaft, that is, at the time of steering, is large, it causes a feeling of friction of the steering system (the steering wheel is felt heavy) and becomes a factor that deteriorates the steering feeling, so that the friction is reduced. It is the current situation that is trying to.

However, according to the inventor's study on the influence of the friction on the steering force characteristics as described above, if the friction can be variably adjusted and provided, the friction is actively utilized. The present inventor has found that the steering force characteristic can be improved in a region where the steering force is large, and the present invention is based on this. More desirable also from the steering state
Even when steering by turning the steering wheel more,
Is to improve the steering feeling appropriately (see
(See FIGS. 5 and 6). Under the concept of designing the friction to be uniformly small regardless of the area where the steering force is small or the area where the steering force is large, the function of variably adjusting and giving the friction is not provided.

[0005] From such a viewpoint, the present invention aims to provide a steering device that embodies the above idea.
More specifically, it is an object of the present invention to improve the steering force characteristics during traveling without deteriorating the steering feeling in a region where the steering force is small. Another object is to provide a steering apparatus for a vehicle which can be applied to both a vehicle with a power steering system and a vehicle without the power steering system and can realize the above.

[0006]

According to the present invention, the following steering apparatus is provided. In a steering apparatus for a vehicle that transmits a steering force of a steering wheel to a wheel via a steering shaft, a friction body capable of generating a frictional force with the steering shaft by contacting the peripheral surface of the steering shaft is provided. And a pressing means for pressing the friction body in accordance with a steering force or a lateral acceleration acting on the vehicle, wherein the pressing force is increased as the steering force or the lateral acceleration increases, and the pressing force is increased according to the characteristic.
Pressing means with increased force actuates the pressing means
Means for steering by rotation of the steering shaft.
Actuates according to the rudder to generate pressing force, and the steering
When steering from the steering state where the wheels are held, the steering
Friction due to the frictional body increases as the force increases.
Steering in this area to obtain a reaction force
Pressure to increase friction when steering from
A steering device for a vehicle, comprising: means for operating the vehicle.

[0007]

The friction member is provided as a member capable of abutting against the peripheral surface of the steering shaft to generate a frictional force between the friction member and the steering shaft, and pressing means for pressing the friction member responds to the steering force or the lateral acceleration. As the steering force or lateral acceleration increases, the pressing force increases. In addition, the characteristics
Pressing means that increases the pressing force activates the pressing means
Means for causing the steering shaft to rotate.
Actuates in response to steering to generate a pressing force,
Steering from the steering state where the ring wheel is maintained
In addition, the higher the steering force, the more the friction
In this area, a reaction force can be obtained by the reaction
Friction increases when steering from a steering hold state
Means for applying a pressing force is provided. As a result, at the time of steering, it is possible to apply a friction that varies according to the steering force or the lateral acceleration, and it is possible to surely increase the friction when the steering force is small in a light range and in a large range. It is possible to improve the steering force characteristics during traveling while avoiding deterioration of the steering feeling in a region where the steering holding force is small (FIGS. 1, 3, 4, 7, 8, 8, 9, 10, 12,
13). Also, increase the turning from the steering
Even in the case of small steering, the larger the steering force,
The amount of friction can be appropriately increased accordingly.
Improved steering feel in such areas when steering from a steering hold state
Can be made. According to a second aspect of the present invention, in a steering apparatus with a power steering mechanism having a control valve that generates an assist pressure that increases with a steering force according to a steering force, the assist hydraulic pressure from the control valve is used. Can be used to operate the pressing means. In this case, the power steering mechanism can be used effectively. In this case, when the configuration and control according to claim 4 are added, Steering force characteristics during traveling can be improved without causing an increase in the steering force in stationary and low speed regions. The present invention also includes those with a power steering mechanism,
A device for improving the steering force characteristic by the configuration and control according to the third aspect (including those according to FIGS. 10, 12 and 13) can be realized. In this case, the vehicle speed can be improved as described in the fifth aspect. Thus, the pressure control valve can be controlled, and appropriate control can be performed.

[0008]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 shows an embodiment of the apparatus of the present invention. FIG. 2 shows an example of a configuration in which the present invention is applied to a steering apparatus with a power steering mechanism (power steering apparatus) showing the overall configuration of the system.

First, a front wheel steering system will be described with reference to FIG. 2. In FIG. 2, reference numeral 1 denotes a vehicle body, and 2L and 2R denote left and right front wheels, respectively. The front wheels 2L and 2R are knuckle arms 4L and 4R, respectively.
To the steering gear 6 via the side rods 5L and 5R.
To the rack 7. A pinion gear 8 meshing with a rack gear portion of the rack 7 is connected to a steering wheel 10 via a steering shaft 9.
L and 2R can be steered.

In the above-described vehicle steering system for transmitting the steering force of the steering wheel to the wheels via the steering shaft, a power steering (P / S) device is further provided for power assisting front wheel steering. The device may be constituted by a mechanism in which a control valve (valve) that operates in response to the steering force and generates an assist pressure that increases with the steering force is interposed in the steering shaft. A power steering control valve 11 is provided in connection with the steering shaft 9, and a power cylinder 12 is provided in connection with the steering gear 6.

The control valve 11 has variable throttles 11a to 11d that respond to a steering load. System further pump comprises a (P / S pump) and reservoir tank 14, the variable throttle 11a, a hydraulic supply circuit 15 ₁ of the hydraulic source between 11c, the variable throttle 11b, the hydraulic pressure source of the drain circuit between 11d 15 ₂ are connected respectively. Also,
The variable throttle 11a, coupling circuit 15 ₃ from among 11d, and the variable throttle 11b, and contact circuit 15 ₄ from among 11c, connecting the chamber 12a of the respective power cylinder 12, the 12b.
These chambers 12a and 12b are defined by a piston 16, which is fixed to a rack and slidably fits in a fixed cylinder body 17.

[0012] A rotary valve can be used as the control valve that operates according to the operating force to increase the pressure of the assist force. FIG. 1 shows a system in which a hydraulic control mechanism and a rack-and-pinion steering mechanism according to such a system are combined. The hydraulic path inside the gear is divided into an input portion (control valve portion) and an output portion (power cylinder portion). .

FIG. 3 shows the structure of the control valve section.
Referring to FIG. 4 showing an example of an operation state thereof, in the present example, a stub shaft 20 (valve shaft) and a valve body 21 are provided on a control valve portion in the same axial direction as the torsion bar 22. When installed in the box 23 and the steering wheel 10 is rotated, the torsion bar 22 rotates integrally with the stub shaft 20. Three grooves are formed on the outer periphery of the valve body 21 in the circumferential direction. Four recesses are formed on the outer periphery of the stub shaft 20, and two holes (return part ( Port) 24)
Are provided respectively, and each groove and hole are provided with the inlet port 25, the outlet port 26, and the piston 1
6 are connected to the cylinder chambers 12a and 12b on both sides.
The stub shaft 20 is coupled to the pinion gear 8 by a lock pin together with the torsion bar 22, and this meshes with the rack gear 27.

The inlet port 25 is connected to an oil pump 13 for power steering, which is composed of a rotor, a vane, a relief valve, a flow control valve, and the like, and is connected to a pressure port for pressing a friction body to be described later. Then, the outlet port 26 reaches the reservoir tank 14. In addition, the communication portion to the cylinder chamber has a function of two output ports for discharging or sucking the pressure oil from the pump 13 in opposite directions according to the steering wheel operation direction and the operation amount (the communication circuit portion in FIG. 2). ).

Further, in this embodiment, in addition to the above configuration, in order to improve the steering force characteristic of the power steering device, the following configuration, that is, the abutment on the outer peripheral surface of the steering shaft,
A frictional body for generating a frictional force is provided between them, and a steering force or a lateral acceleration (lateral G) acting on the vehicle is provided.
A mechanism is provided that has a pressing means for pressing the frictional body in accordance with (1), and that the frictional body pressing force increases as the steering force or the lateral G increases. The friction body can be arranged between the steering wheel in the steering rod and the control valve when the control valve having the above structure is used, and furthermore, the frictional body from the control valve generates an assist force that increases with the steering force. A configuration in which the friction body is pressed by utilizing the assist hydraulic pressure can be employed. In FIG. 1, such a configuration is adopted, and an elastic ring 31 functioning as a friction body is arranged on the rear cover 30 of the gear housing so as to be able to tighten the stub shaft 20. An oil passage 32, which is a groove in which the elastic ring 31 is provided, connects this to a pressure port 33, and the pressure port 33 is connected to the inlet port 25.

The cylinder piston 16 performs power assist by hydraulic pressure controlled by the control valve having the above structure. When the valve body 21 and the stub shaft 20 have the relationship shown in FIG. 3, the assist does not function. That is, in the state of FIG. 3, the hydraulic oil from the pump 13 flows from the inlet port 25 through the groove on the outer periphery of the valve body 21 to the recess around the valve body 21. The hydraulic oil flows from the return part 24 to the stub shaft 20 through the concave portion on the valve body 21 side and the concave portion on the stub shaft 20 side because the circumferential clearance (opening) between the stub shaft 20 and the stub shaft 20 is the same. To the outlet port 26 through the axial gap between the torsion bar 22 and
Return to the reservoir tank 14. Therefore, in this state, there is no pressure difference between the left and right cylinder chambers of the piston 16 and the piston remains neutral. The power cylinder does not function, so that the vehicle can go straight while keeping the front wheels in a non-steering state when the vehicle goes straight.

On the other hand, when the front wheels are steered by the steering wheel 10 via the steering gear, the steering is power assisted by the power steering mechanism to perform light power steering, and at the same time, the hydraulic system of the power steering is operated. The steering feeling is improved by adjusting the tightening according to the steering force of the used elastic ring 31.

First, the operation for the power assist in this case is as follows. When a steering force is applied to the stub shaft 20 by operating the steering wheel, the torsion bar 22 is twisted due to the load on the tire (ground resistance). At this time, the stub shaft 22 and the valve body 21
And a rotational displacement occurs by the amount of the twist, and the rotational displacement controls the pressure and direction of the oil sent from the pump 13 to selectively send the oil to the left or right side of the piston 16. Become. As a result, the piston 16 is power assisted in the corresponding direction, and the front wheels are moved by the required amount via the rack gear 25. In this case, the movement of the stub shaft 20 (relative movement with respect to the valve body as illustrated in FIG. 4) is displaced in accordance with the load on the tire, and accordingly the hydraulic pressure is increased and the output to the cylinder 12 is reduced. Become. The force corresponding to the torsion angle of the torsion bar 22 becomes a reaction force,
The driver can steer right or left while feeling the road surface reaction force according to the load.

Now, assuming that right steering has been performed, in this case, specifically, in FIG. 4 showing a state in which the vehicle is turned to the right, the hydraulic pressure is applied to the chamber 12b side of the piston 16 by the right rotation of the stub shaft 20. Then, power assist the piston 16 to the left (in FIG. 4). That is, the rightward rotation of the stub shaft 20 causes the concave portion of the valve body 21 and the concave portion of the stub shaft 20 to be aligned with each other. It acts on the chamber 12b side of the piston 16 from the port. Accordingly, power assist is applied to the piston 16 that moves to the left in FIG. 1 via the gear, and the force acts to move the rack gear 27 to the left (the direction in which the front wheels are steered to the right) in FIG. The oil pushed out from the chamber 12a side of the cylinder 12 by the piston 16 passes through the concave portion of the stub shaft 20 and the concave portion of the valve body 21, passes through the gap between the stub shaft 20 and the torsion bar 22 from the return part 24, and passes through the outlet. Return from port 26 to reservoir tank 14.

Thus, in the case of right steering, pressure is generated in accordance with the operation amount of the steering wheel 10, and power steering is performed for the right steering of the front wheels, thereby enabling light power steering. Also in the case of a left turn, the left steering is power assisted by the hydraulic pressure generated according to the operating force of the steering wheel 10 according to the above. In this case, FIG.
Although the movement of the middle stub shaft and the flow of oil are opposite to those at the time of turning right, the degree of increase in the pressure of the inlet port 25 depends on the steering force, and therefore the assist increases with the steering force even if the steering direction is reversed. Oil pressure will be generated.

In the power assist as described above, in this embodiment, the friction is added to the shaft by the elastic ring 31 in accordance with the power assist, and this is automatically performed by using the assist hydraulic pressure. That is,
At the time of steering, the torsion bar 22 is twisted with the occurrence of the lateral G due to steering, the pressure of the inlet port 25 is increased by the power steering pump 13, and the hydraulic assist for the steering rack is performed.
As described above, but at that time, the pressure port 33
Has the same pressure as the inlet port 25. When the pressure acts in this manner, the stub shaft 20 is tightened by the hydraulic pressure of the elastic ring 31,
As a result, friction during rotation of the stub shaft increases.

The above-described provision of friction is based on the following viewpoints. First, in the device according to the present embodiment, a friction body that can apply friction when the shaft rotates is arranged on a shaft between the power steering control valve that generates pressure in accordance with the operation amount of the steering wheel and the steering wheel. Although the influence of friction on the shaft on the steering force characteristic is considered, the following can be said.

FIG. 5 is an explanatory view of the operational feeling when the pressing force of the elastic ring 31 as a frictional body against the rotating shaft is controlled by the hydraulic pressure generated according to the operating force of the steering wheel 10 according to the present embodiment. FIG. 6 is a similar explanatory diagram shown as a comparative example, and specifically shows a Lissajous waveform of a steering force and a lateral G in a slalom steering characteristic of a vehicle measured at a predetermined speed. To see FIG. 6, assuming that the steering from the straight state of the vehicle to the right, in this case, the steering force is increased with an increase in lateral G in the direction of arrow a ₁ in FIG., In the state of A ₁ point steering hold Start, B ₁
The steering force drops to a point.

[0024] In the figure, a steering force from falling to _a point B is due to the friction of the steering system, the pressure in accordance with the operation amount of the steering wheel, especially a control valve as in this example intended to include to the system It has been found that this is caused by friction between the steering control valve and the steering wheel. Friction occurs as a stopping force in the process of steering, and if the steering is maintained, there is no equivalent,
As a result, the force required for maintaining the steering when the steering angle and the lateral G are the same is reduced.

When the steering wheel is further turned from the point B ₁ , the steering force increases by an amount corresponding to the friction as shown in the figure, reaches the point C _1, and moves laterally in the direction of the arrow b ₁ . G and the steering force increase. For this reason,
In a region where the steering holding force is somewhat large, even when the steering wheel is further turned from the steering holding state, the above B is applied.
_A reaction force can be felt by the friction of ₁ to C1. Therefore, speaking above掲例, it is possible to improve the steering feeling by increasing the friction component of B ₁ -C _1. On the other hand, if the friction is increased,
In a region corresponding to a small steering force (a range in which the lateral G is small), a feeling of friction of the steering system occurs, and therefore, the steering feeling in that region is deteriorated.

In contrast to the characteristics shown in FIG. 6, in the present embodiment, it is possible to improve the steering force characteristics during traveling without deteriorating the steering feeling in a region where the steering holding force is small in the present embodiment. it can. That is, at the time of power assist, the elastic ring 31 increases friction when the stub shaft rotates with a pressing force corresponding to the assist force. Therefore, the increase in friction is small in a range where the steering force is light, and the friction is increased in a region where the steering force is large, so that the steering feeling can be improved. This is a 5 that shows a characteristic (reference numeral A ₂ etc. in the figure conform to like numerals in FIG. 6), the steering force, it is possible to increase the friction with increasing lateral G. In a region where the steering force is small, the steering feeling does not need to be degraded, and in this embodiment, it is also possible to easily realize the power assist mechanism without using a control valve or the like for separately adjusting friction. it can.

FIGS. 7 and 8 show another embodiment (second embodiment). This embodiment corresponds to a modification of the above-described embodiment (first embodiment), and at least a shaft having a friction material capable of applying friction to a shaft between a control valve and a steering wheel as a friction body. And a member that is divided into two or more members in the circumferential direction is used, and the members are connected by an elastic body. The figure shows a structural example of such a frictional body portion, and the same reference numerals are given to the same components as those in the above-described embodiment. The other specific power assist mechanism (not shown) may be the same as that described with reference to FIGS.

In the following, a description will be given of the main parts. In this example, a pair of plates 41 each having a friction material 40 attached thereto are disposed around the stub shaft 20 so as to face each other. Oil passage 32
Each friction material 4 is applied to the stub shaft 20 by the hydraulic pressure applied to the stub shaft 20.
Press 0. Further, a return spring 43 as an elastic body is connected between the plates 41 so as to release the pressing when the oil pressure in the oil passage 32 connected to the pressure port 33 is reduced.

In the present embodiment, during power assist, the plate 41 applies friction to the stub shaft 20 with the friction material 40 by the hydraulic pressure (assist hydraulic pressure) acting on the oil passage 32. On the other hand, when the oil pressure in the oil passage 32 decreases, the friction material 40 of the plate 41 is separated from the stub shaft 20 by the return spring 43, so that no friction occurs in this state. The basic operation and effect of this embodiment are the same as those of the first embodiment, but in addition to this, the hydraulic pressure (for generating friction) is determined by the setting of the spring constant of the used return spring and the distance between the plates 41. There is an advantage that the steering force can be set. Therefore, there is an effect that no friction is generated in a light steering force range, and the steering force characteristics can be further improved.

FIG. 9 shows still another embodiment (third embodiment). The present embodiment uses an assist oil pressure to press a frictional body that generates friction, and in addition to this, a valve (a switching valve or a pressure control valve) that controls the supply of oil pressure in the oil passage that guides the assist oil pressure. And the like, and controls the opening and closing of the valve based on the vehicle speed. When the vehicle speed is low, the supply of hydraulic oil is limited, and the pressing force of the friction body is reduced or made zero. Here, as the friction element part, the one according to the embodiment (second embodiment) shown in FIGS. 7 and 8 is used. Therefore, this point is a further modification of this embodiment. Further, in view of using the assist oil pressure in the power steering system as the operating oil for the pressing operation, the embodiment described with reference to FIG.
This corresponds to a modification of the embodiment. Note that the same reference numerals are given to the same components already described (the same applies to other embodiments described below when applicable).

In this embodiment, only the essential parts will be described. As shown in FIG. 9, the components for applying friction to the stub shaft 20 are the same as those in FIG. 8 (vertical section corresponding to FIG. 7). Since the drawings are the same, illustration is omitted). The difference from the embodiment according to the case of FIG. 8 is that, as shown in FIG. 9, the valve 50, the controller 51, and the vehicle speed sensor 52 are additionally used.

The valve 50 is a pump 1 for the power steering.
3 is provided between the inlet port 25 and the pressure port 33 where the power steering hydraulic pressure operates. Valve 50
Is an electromagnetic directional switching valve that operates in accordance with a command based on a vehicle speed signal from the controller 51 which receives a vehicle speed signal from the vehicle speed sensor 52, and outputs a control signal from the controller 51 to a solenoid of the valve. Switches between ON and OFF (positions shown). The controller 51 includes, for example, a microcomputer, and controls the switching valve 51 so that the switching valve 50 is turned off when the vehicle speed is lower than the predetermined vehicle speed and turned on when the vehicle speed is higher than the predetermined vehicle speed.

In the case of this embodiment, the steering characteristics during traveling can be further improved without inducing a stationary operation or an increase in the steering force in a low speed range, as compared with the above-described embodiment. That is, when the vehicle speed is lower than the predetermined vehicle speed including the stop state, the electromagnetic directional control valve 50 is in the OFF state shown in the drawing, so that the friction acts on the stub shaft 20 depending on the friction material 40. do not do. On the other hand, when the vehicle speed is equal to or higher than the predetermined vehicle speed, the switching valve 50 is turned on by the controller 51. In this state, a path for transmitting the assist hydraulic pressure generated in accordance with the operation amount of the steering wheel to the pressure port 33 (accordingly, to the friction body). Is formed, which makes it possible to apply pressure at or above a predetermined vehicle speed. Therefore, in this embodiment, the same operation and effect as those of the second embodiment of FIGS. 7 and 8 can be obtained when the switching valve 50 is in the ON state. In the steering in the state, even if the power assist is performed, the supply of the assist hydraulic pressure as the operating pressure to the friction body is cut off in this example, so that the pressing force is zero and the stub shaft 20 does not act on the friction. There is an advantage that the steering force can be reduced by the amount of no friction. In each of the above-described embodiments (first and second embodiments), the steering force is increased due to friction caused by a frictional body in stationary steering or low-speed steering. In the present embodiment, such an increase in the steering force is performed. Thus, the steering force characteristics during traveling can be improved without inducing.

In the illustrated example, a directional control valve is used as a valve for controlling the supply of hydraulic pressure to the pressure port 33. However, this may be a pressure (hydraulic) control valve, and the supply of hydraulic oil when the vehicle speed is low. May be such that the pressing force of the friction body is reduced.

FIG. 10 shows still another embodiment of the present invention (fourth embodiment).
Example) is shown. In contrast to the above-described embodiments (first to third embodiments) in which the pressing means is operated so as to press the friction body by the assist hydraulic pressure of the control valve of the power steering system, the present embodiment is different from the first embodiment. ,
A hydraulic pressure source for supplying hydraulic oil to the pressing means is provided, and a pressure control valve for controlling hydraulic pressure is provided in a hydraulic oil supply oil passage, and the pressure is increased as the steering force or the lateral acceleration increases. This is to control as much as possible.

As shown in FIG. 10, also in the case of this embodiment,
The configuration for applying friction to the stub shaft 20 is the same as that shown in FIGS. 7, 8, and 9. Thus, the pressure port 33 connects this to the electromagnetic hydraulic control valve 60, and the pressure of the pressure port 33 is
0, and the control pressure is controlled by a pump 61 provided separately from the power steering system.
Provided by

The electromagnetic hydraulic control valve 60 has, for example, a supply port 60a, a return port 60b, and a control port 60c as shown in the figure, and is composed of a solenoid 60d, a pilot valve 60e, and a main valve 60f. Can be used. The supply port 60a is connected to the pump 61, the return port 60b is connected to the reservoir tank 62, and the control port 60c is connected to the pressure port 33. The solenoid drive current of the hydraulic control valve 60 is controlled by the controller 51,
As a result, the output pressure of the control port 60c, that is, the oil pressure P of the pressure port 33 is controlled.

The controller 51 receives running state detection information, and the hydraulic control valve 60 controlled by the controller 51 generates an external force for pressing the friction body based on the running state detection signal. It constitutes an external force generating means. In this configuration in which the operating pressure system for the frictional body can be a separate system, a signal from a lateral G sensor 63 for detecting, for example, lateral G generated in the vehicle is input to the controller 51, and more preferably, a hydraulic control valve 60. The input from the vehicle speed sensor 52 is also input in order to control the vehicle speed according to the vehicle speed. Note that a steering force signal may be input instead of the lateral G.

When the hydraulic control valve 60 is controlled based on the lateral G and the vehicle speed signal, the controller 51 is used.
According to the characteristics shown in FIG. 11, the control valve 60 is controlled so that the control pressure P increases as the lateral G increases, and the control pressure P decreases as the vehicle speed decreases.
Is performed on the solenoid drive current to control the pressing force of the friction body against the stub shaft 20. The control hydraulic pressure P (solenoid drive power) -lateral G (or steering force) characteristic as shown in FIG. 11 used for the control can be determined independently of the assist hydraulic characteristic even in a vehicle equipped with a power steering system. Can be set and stored in the storage unit in the controller 51 in advance as table data of each control parameter including “.

According to the present embodiment, the pressing force against the friction body can be controlled with the same tendency as the characteristics obtained in each of the above embodiments, and the pressing force can be reduced as the vehicle speed becomes lower. . In addition, in the above-described configuration, an appropriate friction can be given to the stub shaft 20 by the lateral G and the vehicle speed independently of the assist hydraulic pressure, so that the steering feeling can be improved, and the degree of freedom in tuning the steering feeling can be greatly increased. be able to.

The following is an embodiment when applied to a vehicle having no power steering mechanism (non-P / S vehicle). 12 and 13 show an example of the configuration, FIG. 14 shows an example of the characteristic, and FIG. 15 shows an outline of a front wheel steering system of an applicable vehicle.

When the present invention is applied to a non-P / S vehicle as shown in FIG.
As shown in FIG. 3, a friction member for giving friction is provided. Here, the configuration for applying friction to the steering shaft 9 is the same as that shown in FIGS. 7, 8, 9, and 10, that is, the friction member 40, the plate 41, the spool 42, the return spring 43, and the like. However, an elastic ring or another form as shown in FIG. 1 is used to abut on the peripheral surface of the steering shaft 9 to generate a controllable frictional force with the steering shaft 9. You may. Further, in the case where the frictional body is pressed, the pressing force is increased as the steering force or the lateral G is increased in accordance with the steering force or the lateral G, and the frictional body is pressed similarly to or similar to that shown in FIG. Can be used, and here, FIG.
0 is used.

That is, as shown in the figure, the apparatus comprises a hydraulic source including a pump 61 for supplying hydraulic oil, an electromagnetic hydraulic control valve 60 for controlling the hydraulic pressure of the hydraulic oil, and A control system including a controller 51 for controlling the pressure of the pressure port 33 to vary and a lateral G sensor 63 is provided. In this case, the input by the lateral G sensor may be a steering force signal as in the case described above. The controller 51 also preferably controls the control valve 60 with the vehicle speed sensor 5.
The control is also performed based on the detected vehicle speed of No. 2, and when the vehicle speed is low, the pressure is controlled to be reduced. Controller 51
Therefore, the horizontal G has the same tendency as in FIG.
And a table for setting the control oil pressure according to the vehicle speed is stored, and the control is executed based on the table.

With the above configuration, even in a steering device in the case of a non-P / S vehicle, even when the steering wheel is operated,
Horizontal G with frictional body against rotating steering shaft
The friction force can be given by increasing the pressing force of the friction body as the value increases. FIG. 14 is an example of the lateral G-one steering force characteristic that can be realized in the case of this example. Looking at the figure,
In this case, the characteristic during steering is different from that shown in FIG. 5 and is linear because there is no power assist. However, during steering, the characteristic is similar to that shown in FIG. In the present embodiment, the structure in which friction is applied and the structure in which control is also performed according to the vehicle speed, etc., adopt the structures in FIGS. 7 to 11. It also has the already mentioned advantages obtained. Further, the present invention provides a P / S
When the present invention is applied to a vehicle, it is needless to say that the present invention is not limited to the rotary valve type as shown in FIG. 1, and can be implemented as long as it has the basic power steering system as shown in FIG. Fig. 1 also for P / S vehicles
It is not limited to five.

[0045]

According to the steering apparatus of the present invention, the friction of the steering system can be variably adjusted and increased as the steering force or the lateral acceleration increases, and in this case, the pressing means is used. , The pressing
Means for actuating the steering means.
It operates according to the steering by the shaft rotation to generate the pressing force,
Steering from the holding state where the steering wheel is held
The higher the steering force, the higher the frictional force
To obtain a reaction force due to the friction
Friction increases when steering from the holding state in this area
Do this by providing means for applying a pressing force to
Therefore, it is possible to surely improve the steering force characteristics during traveling without deteriorating the steering feeling in a region where the steering holding force is small, and to increase the steering angle from the steering holding state.
Even in cases where the steering force is larger,
The amount of friction can be increased appropriately, and
It is possible to improve the steering feeling in such an area during steering.
The present invention can be applied to both a vehicle having a power steering mechanism and a vehicle not having the mechanism, and can provide a steering device that can contribute to an improvement in steering force characteristics of the vehicle. In the case of claim 2, the above can be realized by effectively using the power steering mechanism described in the claim. In the case of claim 4, the steering force in the stationary and / or low speed range is increased. Can be avoided. In the case of the third and fourth aspects, the steering force characteristic can be similarly improved by the configuration and control described in the same aspect, including a vehicle with a power steering mechanism.

[Brief description of the drawings]

FIG. 1 is a diagram showing an embodiment of the apparatus of the present invention.

FIG. 2 is a configuration diagram of a front wheel steering system including an outline of the system in a vehicle of a steering device with a power steering mechanism to which the present invention can be applied.

FIG. 3 is a diagram provided for describing the configuration of the control valve unit in FIG. 1, and is a state explanatory diagram when the straight running is not operated.

FIG. 4 is a diagram showing an example of an operation state (at the time of turning right).

FIG. 5 is an explanatory diagram of a steering feeling of the embodiment device, showing a slalom steering force characteristic of the vehicle.

FIG. 6 is a similar characteristic explanatory diagram shown as a comparative example.

FIG. 7 is a view showing a configuration according to another embodiment of the present invention, and is a structural view of a friction element part.

FIG. 8 is a sectional view taken along line XX of FIG. 7;

FIG. 9 is a diagram showing a configuration according to still another embodiment of the present invention.

FIG. 10 is a diagram showing a configuration according to still another embodiment.

FIG. 11 is a diagram showing an example of control characteristics applicable to control in the control system of FIG.

FIG. 12 is a diagram showing a configuration according to still another embodiment of the present invention, showing an example of a configuration of a frictional element portion and an example of a configuration of a control system.

FIG. 13 is also a longitudinal sectional view of the friction element part.

FIG. 14 is a diagram showing an example of a lateral G-one steering force characteristic.

FIG. 15 is a diagram of a front wheel steering system showing another example of a vehicle to which the present invention can be applied.

[Explanation of symbols]

 1 Body 2L, 2R Left and right front wheels 6 Steering gear 7 Rack 8 Pinion gear 9 Steering shaft 10 Steering wheel 11 Power steering control valve 12 Power cylinder 12a, 12b Cylinder chamber 13 Pump 14 Reservoir tank 16 Piston 20 Stub shaft 21 Valve body 22 Torsion bar 23 Steering gear box 24 Return part 25 Inlet port 26 Outlet port 27 Rack gear 30 Rear cover 31 Elastic ring 32 Oil passage 33 Pressure port 40 Friction material 41 Plate 42 Spool 43 Return spring 50 Electromagnetic directional control valve 51 Controller 52 Vehicle speed sensor 60 Electromagnetic Hydraulic control valve 61 Pump 62 Reservoir tank 63 Lateral G sensor

Claims (5)

(57) [Claims] 1. A steering apparatus for a vehicle that transmits a steering force of a steering wheel to wheels via a steering shaft, wherein a frictional force is generated between the steering shaft and the steering shaft by contacting the peripheral surface of the steering shaft. provided with a Do friction body, the steering force or lateral acceleration is configured to enhance more the pressing force becomes larger with a pressing means for pressing the friction member according to the lateral acceleration acting on the steering force or the vehicle, the Pressing means that increases the pressing force according to the characteristics
Is means for operating the pressing means, and
Operates according to the steering due to the rotation of the ringing shaft and presses
And the steering wheel that holds the steering wheel
When steering from the state, it is more likely to be in the region where the steering force is large.
The reaction force is obtained due to the friction of the friction body
During steering from the steering holding state in this area,
Equipped with a means to apply a pressing force to increase the
Becomes, steering system for a vehicle, characterized in that. 2. The steering device according to claim 1, wherein the steering device includes a control valve in the steering shaft that operates according to the steering force and generates an assist pressure that increases with the steering force. A steering device for a vehicle, wherein the pressing means is operated by an assist hydraulic pressure of the control valve. 3. The pressure control valve according to claim 1, further comprising: a hydraulic pressure source for supplying hydraulic oil to the pressing means; and a pressure control valve for controlling hydraulic pressure in a hydraulic oil supply oil passage. Alternatively, a steering device for a vehicle, further comprising control means for controlling to increase the pressure as the lateral acceleration increases. 4. The frictional body according to claim 2, wherein a valve capable of controlling the supply of hydraulic pressure is provided in an oil passage for guiding assist hydraulic pressure to the pressing means, and the supply of hydraulic oil is restricted when the vehicle speed is low to press the friction body. A steering apparatus for a vehicle, comprising control means for controlling the valve based on the vehicle speed so that the force is reduced or zero. 5. The vehicle steering apparatus according to claim 3, wherein the control means controls the pressure control valve also according to the vehicle speed, and lowers the pressure when the vehicle speed is low.