JPS628863A - Power steering device - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Industrial Application Field] This invention detects physical quantity elements that change the steering torque of an input shaft that steers a vehicle depending on the running and steering conditions of the vehicle, and responds to changes in the physical quantity. The present invention relates to a power steering device that changes the steering feel, and particularly relates to a power steering device that can change the steering angle ratio according to the physical quantity elements.

[Conventional technology]

Conventionally, as a power steering device capable of changing the ratio between the steering angle of the steering wheels and the turning angle of the wheels, for example, the Japanese Patent Publication No. 58
There is one described in Japanese Patent No.-5826.

This device includes a power device that provides auxiliary power when steering the wheels of a vehicle, a switching valve that controls the power device via a shaft depending on the steering direction of the steered wheels, and a switching valve that is always biased to a neutral position. In a power steering system, a power steering system includes a spring device that provides a steering reaction force proportional to the road resistance of the wheels, and a reaction force mechanism that provides a steering reaction force proportional to the road resistance of the wheels. A power steering device for a vehicle, characterized in that it is configured to obtain a variable steering angle ratio by interposing an elastic means that provides rotational displacement within a range of a spring constant, and the power steering device is characterized in that it is configured to obtain a variable steering angle ratio. The steering angle ratio is set as small as possible to obtain a large turning angle of the steered wheels with a slight rotation of the steered wheels, and the steering angle is set to be as small as possible to prevent the so-called steering wheel from turning too much as when steering at high speeds. It is possible to satisfy conflicting demands such as setting a large ratio and ensure steering stability.

[Problem that the invention seeks to solve]

However, in the above-described conventional power steering device, elastic means such as a torsion bar provides a rotational displacement between the steering shaft of the switching valve and the steered wheels in accordance with the steering torque within a range of a spring constant of a road type. In order to increase the steering angle ratio and the torsion angle of the elastic means, it is necessary to set the torsion bar spring constant low. Therefore, there is a problem in that the torsional rigidity of the torsion bar is reduced, and the steering feeling of the entire steering system is reduced.

Therefore, the present invention makes it possible to reduce the steering angle ratio when stopped or running at low speed, and to increase the steering angle ratio when running at high speed, without reducing the torsional rigidity of the elastic body, thereby improving the steering feeling. The purpose is to provide a power steering device.

[Means for solving problems]

In order to achieve the above object, the present invention provides an input shaft for steering a vehicle, a power device for generating a steering assist force in accordance with a steering torque applied to the input shaft, and a steering control force applied to the input shaft. a steering reaction force generation mechanism that generates a reaction force that resists the torque; a switching valve that controls the power unit and the steering reaction force generation mechanism according to the direction of the steering torque applied to the input shaft; A power steering system is provided, which includes a detection means for detecting a physical quantity element that changes depending on the state, and a selection means for selecting an operating ratio of the power plant and the steering reaction force generating device according to the detection result of the detection means. an elastic body interposed between the input shaft and the switching valve and generating a rotational displacement with respect to the input shaft in the same direction as the steering direction in response to the reaction force of the steering reaction force generation mechanism; The present invention is characterized in that it is provided with a steering angle ratio variable mechanism comprising rotational displacement generating means for causing rotational displacement.

[Effect]

In this invention, a relatively rigid elastic body is inserted between the input shaft for steering the vehicle and the control valve for controlling the power plant, and this elastic body allows the connection between the input shaft and the control valve to be The steering angle ratio can be changed by allowing rotational displacement, and when driving at high speeds when a reaction force is required against the steering torque applied to the input shaft, the steering angle ratio can be changed based on the steering reaction force generated by the steering reaction force generation mechanism. By actively displacing the input shaft in the same direction as the steering direction using the rotational displacement generating means, the steering angle ratio is set to a large value to ensure driving stability, and while maintaining a good steering feel, the steering angle ratio is can be changed depending on the driving condition.

〔Example〕

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

FIG. 1 is an overall configuration diagram showing an embodiment of the present invention.

In the figure, reference numeral 1 denotes a steering wheel, and a steering shaft 2 serving as an input shaft connected to the center of the steering wheel passes through a column tube 3 and is connected to a variable steering angle ratio mechanism 4. An output shaft 5 is connected to a variable steering power steering device 7 via a universal joint 6.

As shown in FIG. 2, the variable steering force power steering device 7 includes a variable orifice valve 8 as a selection means, a low clearance switching valve 9, a power cylinder 10 as a power device, and a steering reaction force generation mechanism 1). It is composed of.

The variable orifice valve 8 has an input port 8a connected to a pump 13 that discharges a constant flow rate through a flow path 12, drain ports 8b and 8c connected to a tank 14, and output ports 8d and 8e that have a variable flow rate. , a return port 8f, and a spool 8 whose sliding position is controlled by an electromagnetic solenoid 8g.
h and a return spring 81, and the spool 8
h is moved, and in the neutral state shown in Figure 2, the spool 8
h, the input port 8a maintains a predetermined opening degree and communicates with each of the output boats 8d and 8e, and the return boat 8f communicates with the drain boat 8b. When the amount of current to the electromagnetic solenoid 8g is increased (or decreased) from this state, the spool 8h moves leftward (or rightward), increasing the communication area of the output port 8e (or 8d) with respect to the human-powered boat 8a, and The communication area of the output capo 8d (or 8e) decreases, and the sum of the communication areas of both is always greater than a certain value. Furthermore, when the communication area of the input/output boat 8d with respect to the input port 8a decreases, the input/output port 8d and the drain boat 8C become in communication with each other, and the pressure fluid supplied to the input/output port 8d is transferred to the drain boat. It is returned to the tank 14 through 8c.

The electromagnetic solenoid 8g is controlled by a drive current from the control device 15. The control device 15 receives detection signals from a steering angle sensor 16 that detects the steering angle of the steering wheel 1 and a vehicle speed sensor 17 that detects the vehicle speed. is supplied, predetermined arithmetic processing is executed based on these, a drive current command value for the electromagnetic solenoid 8g is calculated, and the amount of current supplied to the electromagnetic solenoid 8g is controlled accordingly. Here, the control by the control device 15? 1) An example of type B is expressed by the relationship between the communication area of the variable orifice valve and the vehicle speed, as shown in FIG. In FIG. 5, the curves indicated by solid lines are the input/output port 8e and the input port 8a.
The curve shown by the dotted line represents the aperture area of the variable diaphragm A2 formed between the input/output port 8d and the input port 8a, and the curve shown by the chain line represents the aperture area of the variable diaphragm A2 formed between the input/output port 8d and the input port 8a. The opening areas of the variable aperture Ao configured between the output port 8d and the drain boat 8c are shown.

The rotary switching valve 9 includes a cylindrical housing 9a, an outer sleeve 9b fitted into the housing, and a rotary spool that is rotatably fitted into the housing 9a and integrally formed with an input shaft 20 (see Fig. 3). 9C.

A pair of input boats 9d+, 9di; 9e++ 9ez are formed in the outer sleeve 9b at equal intervals, and are connected to the output ports of the variable orifice valve 8, respectively, on both sides of the input boats 9d+; 9dt. Adjacent to the entrance and exit ports respectively 9ft, 9g+; 9
rz.

9gz is an input boat 9eI; flow paths 9L, 9j+i 9ht, and 9it are formed adjacent to both sides of 9ez, respectively.

In addition, the outer sleeve 9 is attached to the low crystal spool 9c.
There are input and output capos at positions opposite to the channels 9h+, 9L, 9hz, and 9Lg of b) 9L, 9+, and 9jz.

9kg is formed, input port 9d+, 9d4i 9e
Fluid passages 91. ~91
J is formed, and a drain flow path 9m+ to 9m4 is formed between the input and output boats, and each drain boat 9m1
~9mi is connected to the return boat 8f of the variable orifice valve 8 through a cavity 9n in the rotary spool 9c. Here, fluid passage 91. ~914 and the drain channels 9peng and ~9ma each have input/output ports facing each other at both ends and a small opening area when the rotary spool 9C is in the neutral position as shown in FIG. It's communicating.

The power cylinder 10 has a piston rond 10a that is, for example, a rack shaft of a rank-and-pinion type steering gear, and a steering rond (not shown) at both ends.
Left and right steered wheels (not shown) are connected to each other so that they can be steered. One of the pressure chambers 10c and 10d defined by the piston 10b is connected to the input and output ports 9L and 9fz of the low-flow switching valve 9, and the other is connected to the input and output ports 9g+ and 9gz, respectively.

The steering reaction force mechanism 1) has a cylindrical hollow part 1) a symmetrically sandwiching the central axis at the upper end of a pinion shaft 21 as an output shaft.
.
A pressure chamber 1) e
, '1) f; l1g, llb are formed. Further, the end of the input shaft 20 is rotatably inserted into the center of the pinion shaft 21, and the engagement protrusions 20a and 20b formed at symmetrical positions are engaged recesses 1) i formed in the plungers llc and lid. , llj. Then, the pressure chambers lie and llb are connected to the input and output ports of the low pressure control valve 9) 9j+, 9jz, and the pressure chambers 1)f and 1g
are connected to input/output boats 9kl, 9 and 2, respectively. In this case, pressure chamber 1) e, llh and input/output boat 9
As shown in FIG. 3, L and 9jt communicate with each other through a flow path 9o formed inside the rotary spool 9c and a flow path 9p formed between the lower end of the outer sleeve 9b and the lower end of the row sleeve 9c. , similarly pressure chamber 1) f,
Ilg and input/output boat 9 +, 9kz are the flow path 9q formed inside the rotary spool 9C, the flow path 9r formed in the outer sleeve 9b, the flow path 9s formed in the housing 7a, and the pinion shaft 21. They are communicated through a flow path 9t.

As shown in FIG. 3, a torsion bar 23 is inserted between the human power shaft 20 and the pinion shaft 21. This torsion bar 23 is installed in a through hole 24 formed in the axis of the input shaft 20, and its upper end is connected to the input shaft 20 by a pin 25, and its lower end is connected to the pinion shaft 21 through serrations. 21 is the rack shaft 26
is engaged with.

The lower end of the torsion bar 23 is supported by a bearing 1 ) 1 fitted into the lower end of the through hole 24 of the human power shaft 20 so as to be rotatable relative to the lower end of the input shaft.

The connection relationship of the above-mentioned variable steering force power device 7 is expressed in a hydraulic circuit diagram as shown in FIG. 4. In the figure, reference numerals 27 and 28 indicate directional switching valves, and the directional switching valves 27 are the input/output capos 1-9ct+, 9dg, 9f of the low-flow switching valve 9.
Compatible with l, 9fg, 9g+, 98z,
The directional switching valve 28 is connected to the input/output boats 9e+, 9ez+
9j+.

Compatible with 9Jz, 9 +, and 9kz.

As shown in FIG. 6, the variable steering angle ratio mechanism 4 includes a housing 31 fitted onto the column tube 3, an output shaft 5 rotatably held within the housing 31, and a steering wheel serving as an input shaft. A torsion bar 32 is inserted between the shaft 2 and the output shaft 5 and is an elastic body having a relatively high torsional locking property of approximately 1 5 kgfcm/deg, and a steering shaft 2 is formed at the upper end of the output shaft 5. and a rotational displacement generating means 33 for applying rotational displacement to the rotational displacement.

The torsion bar 32 is rotatably inserted into a through hole 2a formed in the steering shaft 2, and its upper end is fixed to the steering shaft 2 by a pin 34, and its lower end is similarly connected to the output shaft by a pin 35. 5
is fixed.

As shown in FIG. 7, the rotational displacement generating means 33 has a cylindrical cavity 3 symmetrically located at the upper end of the output shaft 5 with the central axis in between.
3a, 33b are formed, and these hollow parts 33a, 33b
Plungers 33c and 33d are inserted at the center positions of the plungers 33c and 33d, respectively, and pressure chambers 33e,
33f; 33g and 33h are formed. Also,
The end of the steering shaft 2 is rotatably inserted into the center of the output shaft 5, and an engagement protrusion 2 is formed at a symmetrical position.
b, 2c are engaged in engagement recesses 33i, 33j formed in plungers +33C, 33d. And the sixth
As shown in the figure, pressure chambers 33e and 33h are connected to a flow path 33 formed in the output shaft 5, a flow path 331 formed between the outer peripheral surface of the output shaft 5 and the inner peripheral surface of the housing 31, and the inside of the housing 31. The housing 3
It communicates with the input/output boat 33n formed on the outer peripheral surface of 1,
This input/output boat 33n is connected to the input/output boats 9kl, 92 of the rotary control valve 9 shown in FIG. Here, + to the input/output boat 33n and the input/output boat 9,
The input/output boat 33n and the flow path 9s branched from the flow path 9u in the housing 7a shown in FIG. 3 are connected to each other by a fluid piping 37. On the other hand, the pressure chambers 1) f and l1g are connected to a flow path 330 formed in the output shaft 5 shown in FIG. 6, a flow path 33p formed between the outer peripheral surface of the output shaft 5 and the inner peripheral surface of the housing 31, and the The input/output boat 33r formed on the outer circumferential surface of the housing 31 is connected to the input/output boat 9j1.31 of the rotary control valve 9 shown in FIG. 9jz respectively.

Here, the input/output boat 33r and the input/output capo)j+,
9jz refers to the pressure chambers 1) e, 1) h in the steering reaction force generating mechanism 1) shown in FIG. The serration fitting part 1)n of the pinion shaft 21 communicates with the flow path 1)p formed in the center of the pinion shaft 21 through the flow path 1)p formed in the cap 7b screwed onto the lower end of the housing and the fluid piping 38. has been done. In addition, in FIG. 6, the oil seal 33s and plungers 33c, 33
The fluid leaking from d etc. is removed through a flow path 33 formed in the output shaft 5 and a flow path 3 formed on the outer peripheral surface of the lower end of the torsion bar 32.
3u is collected in a cavity 33v formed at the upper end of the output shaft 5, and the fluid that overflows from this passes through the bearing 331) and is supplied to the drain port 33y through a pair of check valves 33x, and this drain port 33y is connected to the variable It is connected to the return boat 8f of the orifice valve 8.

Next, the operation of the above embodiment will be explained. Assuming that the vehicle is now in a stopped state, in this state the vehicle speed is zero, so the drive current value output from the control device 15 is the maximum, and therefore the spool 8h is set to the return spring by the electromagnetic solenoid 8g. 81 and is held at a position moved to the left. Therefore, the variable orifice valve 7 is
As shown in FIG. 5, the input port 8a and the input/output port 8
e, the communication area between the input port 8a and the input/output boat 8d becomes zero, and the communication area between the input/output boat 8d and the drain port 8c becomes the maximum. .

As a result, all the pressure fluid supplied from the pump 13 is supplied to the input/output boat 8e, and this is supplied to the input boats 9d+ and 9dz of the low-pressure switching valve 9. At this time, when the steering wheel 1 is not stationary, as shown in FIG.
Pressure fluid is supplied from the flow path 9L i 9jz to the input/output boats 9fl, 9g+; 9f2. 9gg and the pressure chambers 10c; 10d of the power cylinder 10
However, since both pressure chambers 10c and 10d have equal pressure, the piston rod 10a is stopped at the center position, and the steered wheels are maintained in the straight-ahead traveling position. For this reason,
The pressure fluid divided into each input/output boat 9L, 9g+i 9h, 98z is transferred to the adjacent drain channel 9kt~9.
The liquid flows into the tank 14 through the cavity 91, the return port 8f of the variable orifice valve 8, and the drain port 8b.

Furthermore, when the steering wheel 1 is turned rightward (or leftward) in this stopped state, the steering force of the steering wheel 1 is applied to the steering shaft 2, the torsion bar 32 which has relatively high torsional rigidity, the output shaft 4, and the universal joint. Since it is transmitted to the input shaft 20 via the int 5,
The rotary spool 9C of the rotary switching valve 9 rotates clockwise (or counterclockwise) as seen in FIG. For this reason,
Input port 9'l+9d, and input/output port 9g
+, 9gg (or 9f+, 9fz)
, 9ft (or 9g++ 9gg), the pressure on the pressure chamber 10d (or 10c) side of the power cylinder 10 is reduced to the pressure chamber 10c (or 9g++ 9gg).
or 10d) side, the piston loft is 1
0a'' moves to the right (or left) to generate a predetermined steering assist force, making it possible to easily set the vehicle stationary.

At this time, due to the movement of the piston rod 10a, the fluid pushed out from the pressure chamber 10c (or 10d) is transferred to the input/output ports of the rotary switching valve 9) 9r+, 9rt (or 9
The tank 1
Returned to 4.

When the vehicle starts running from a stopped state and the vehicle speed increases, the drive current output from the control device 15 decreases accordingly, so that the spool 8h of the variable orifice valve 8 is moved to the right by the return spring 81. As a result, the communication area between the input port 8a and the output port 8e decreases, and the fluid pressure supplied to the power cylinder 10 also decreases, resulting in a decrease in steering assist force. The thrust of the shaft 26 decreases as the vehicle speed increases, as shown in FIG.

In FIG. 8, when the input shaft torque TH increases beyond a certain value in a relatively low vehicle speed range, the rack shaft thrusts F and I only slightly increase. The reason for this is
Since the supply pump 13 is provided with a relief circuit,
This is because power assistance is not provided above a certain value.

On the other hand, the communication area between the input port 8a and the output port 8d of the variable orifice valve 8 increases as the vehicle speed increases, as shown in FIG.
Since the communication area between the rotary switching valve 9 and the rotary switching valve 9 is reduced, a part of the pressure fluid supplied from the pump 13 is supplied to the input port 9e++ 9ez of the rotary switching valve 9 via the output port 8d. Therefore, when the steering wheel 1 is turned to the right (or left), the rotary spool 9C of the rotary switching valve 9 rotates clockwise (or counterclockwise). Accordingly, the input/output port 9i1.9iz (or 9h,.

The pressure of the pressure fluid on the 9h2) side is the input/output capo)9h+.

9h, (or 9i+, 9i meaning) side, and this is the pressure chamber 1)e, 1)h( of the steering reaction force mechanism 1).
or llf, l1g), the plungers 1)c and 1)d act on the input shaft 20 with a couple in the opposite direction to the steering direction as a steering reaction force, which improves the steering feel of the steering wheel 1. It is possible to prevent the steering wheel from becoming heavy and causing sudden steering. Here, the pressure of the power cylinder 10 and the steering reaction force mechanism 1 are expressed using the vehicle speed V as a parameter.
) and the pressure is as shown in FIG.
At a predetermined vehicle speed vH at which the communication areas of d and 8e are equal, in a low vehicle speed range the pressure in the power cylinder 1O is greater than the pressure in the steering reaction force generating mechanism 1), and in a high vehicle speed range, on the contrary, the steering reaction force increases. The pressure of the generating mechanism 1) becomes larger than the pressure of the power cylinder IO, and an optimal steering feeling can be obtained depending on the vehicle speed.

In this way, the input/output ports 9i0. of the rotary switching valve 9.
9iz (or 9hl, 9hz), this pressure fluid is also supplied to the input port 33n (or 33r) of the variable steering angle ratio mechanism 4. Therefore, the pressure fluid supplied to the input port 33n (or 33r) flows through the flow path 33m.

33m! , 33k (or flow path 33q, 33p
, 330), the pressure chamber 33e of the rotating mechanism 33
, 33h (or 33f, 33g). Therefore, the plungers 33c and 33d move so as to generate a force couple that rotationally displaces the steering shaft 2 in the steering direction. As a result, the steering angle displacement of the steering shaft 2 is increased against the torsional rigidity of the torsion bar 32, and the steering angle ratio is increased.

The relationship between the reaction oil pressure supplied to the pressure chambers 33e, 33h, 33f, and 33g of the rotational displacement generating means 33 and the torsion angle of the torsion bar 32 is as shown in Fig. 1θ, as the reaction pressure increases. There is a proportional relationship that increases accordingly.

Next, changing the steering angle ratio by the variable steering angle ratio mechanism 4 will be explained. First, the steering angle θS of the steering wheel 1 can be expressed by the following equation.

θ5=06+θ θ,=n6　・θ.

... where θ is the tire rotation angle, T is the steering torque acting on the steering wheel 1, K is the spring constant of the torsion bar 32, SP is the area of the plungers 33c and 33d, PR is the reaction oil pressure, R is the length (radius) of the engagement projections 2b, 2c of the steering shaft 2 from the center of the input shaft 20.

In addition, the relationship between the steering torque acting on the steering wheel l and the reaction oil pressure is as shown in Figure 1). In the low vehicle speed region, as shown by the solid line, there is almost no reaction oil pressure, and the reaction oil pressure at that time is The steering torque is small because only the torque required is the product of the angle (approximately 36) that closes off the rotary spool 9C of the rotary switching valve 9 and the spring constant of the torsion bar 23. Further, in a high vehicle speed region, as shown by the dotted line, the reaction oil pressure rises even if the steering torque is small and the rotary spool 9c of the rotary switching valve 9 does not rotate much (approximately 1 inch).

Therefore, if the torsion angle θ8 of the torsion bar 32 in the variable steering angle ratio mechanism 4 is calculated by changing the steering torque based on the formula (1) □, it will be as shown in FIG. 12, and from this FIG. It can be seen that the torsion angle θ□ in the high vehicle speed region is several times larger than the torsion angle θ in the low vehicle speed region with respect to the steering torque.

On the other hand, the relationship between steering torque and steering angle is as shown in FIG. 13 in a high vehicle speed region and as shown in FIG. 14 in a low vehicle speed region. In each figure, the solid straight line indicates the stiffness characteristic due to the self-lining torque of the tire, which increases as the vehicle speed increases.

Therefore, the angle at which the input shaft 20 of the rank and pinion rotates to rotate the tire based on the self-lining torque of the tire is θ in the high vehicle speed region and the low vehicle speed region, respectively. , θGL, by adding the torsion angles θ□, θ1 of the variable steering angle ratio mechanism 4 to these, respectively, the total steering angle θ8. l, θ, and L can be found.

03N=θ, +θ■ ・・・・・・・・・・・・(
2) θ, L-θ1+θ1 ・・・・・・・・・・・・
-(3) Then, the steering angle ratio between the tire rotation angles θ□, θ ridge and the total steering angle θ, , θ3L, of the steering wheel 1 is as follows.

Here, as is clear from FIG. 12, the weeping angle θ, H and θRL of the variable steering angle ratio mechanism 4 are θRH>θIIL, and the higher the vehicle speed, the greater the steering assist torque. Therefore, for the same steering torque, the higher the vehicle speed becomes, the smaller it becomes, θ, 4M<θIIL.

Therefore, the value of the second term on the right side of equations (4) and (5) is thick (different), and in the end the steering angle ratio is nGH>n
Gt, and the steering angle ratio n1)M in the high vehicle speed region becomes a much larger value than the steering angle ratio n0 in the low vehicle speed region.

As a result, an optimal steering response can be obtained in all regions from a low vehicle speed region to a high vehicle speed region.

That is, the torsional rigidity of the torsion bar 32 is selected to be a large value, and in the low vehicle speed region, no rotational displacement is applied to the steering shaft 2 by the rotational displacement generating means 33, and the steering force of the steering wheel 1 is set to a relatively high torsional rigidity. Because the slight rotational displacement caused by the slight twist of the torsion bar 32 itself is transmitted to the steering assist force generation device, the steering force can be transmitted in the same way as in a normal torsion bar 32. Since the rotational displacement generating means 33 generates a rotational displacement in the steering direction to actively increase the rubbing angle of the torsion bar 32, it is possible to prevent the so-called steering wheel from turning too much when steering at high speed. straight-line stability can be guaranteed.

As described above, according to this embodiment, the steering reaction force generating mechanism 1
) is supplied to the rotational displacement generating means 33 of the variable steering angle mechanism 4, thereby eliminating the need for piping to connect to the tank 14 and simplifying the piping layout. In addition to being able to reduce costs,
Since the steering angle ratio variable mechanism is disposed around the steering shaft 2 serving as the input shaft, the overall configuration can be simplified and miniaturized.

In the above embodiment, a case has been described in which a couple force is applied to the steering shaft 2 in the same direction as the steering direction by the plungers 33c and 33d, which are applied to the variable steering angle ratio mechanism 4 by reaction hydraulic pressure. It is also possible to omit the plunger and apply rotational displacement to the steering shaft 2 using only the other plunger.

Further, in the above embodiment, a case has been described in which the plungers 33c and 33d directly apply a couple force to the steering shaft 2 to cause rotational displacement, but the present invention is not limited to this, and the plunger is placed in a rack. It may also be connected to the steering shaft 2 via a transmission mechanism such as an and-binion.

Further, in the above embodiment, a case has been described in which the torsion bar 32 is applied as the elastic body of the variable steering angle ratio mechanism 4. obtain.

〔Effect of the invention〕

As explained above, according to the present invention, the rotational displacement generating section of the variable steering angle ratio mechanism actively uses the reaction force of the steering reaction force generation mechanism that generates a steering reaction force in the opposite direction to the steering force. Since it is configured to apply rotational displacement in the steering direction to the input shaft, that is, the elastic body, the torsion angle of the elastic body can be controlled by the rotational displacement generating section, and thereby the torsional rigidity of the elastic body can be selected to a large value. This makes it possible to achieve the effect that an optimal steering feeling can be obtained in all conditions from low vehicle speed to high vehicle speed.

[Brief explanation of the drawing]

Fig. 1 is a block diagram showing a schematic configuration of the present invention, Fig. 2 is a system outline of a variable steering power steering device, a variable orifice valve, a rotary switching valve having a cross section on the line ■-■ in Fig. 3. 3 is an explanatory diagram showing the connection relationship of the steering reaction force generating mechanism, which is a cross section on the line ■-■ in FIG. 3. FIG. 3 is a longitudinal sectional view of the variable steering force power steering device, and FIG. A hydraulic circuit diagram of the steering device, Fig. 5 is a graph showing the relationship between vehicle speed and the communication area of each part of the variable orifice valve, Fig. 6 is a vertical cross-sectional view of the variable steering angle ratio mechanism, and Fig. 7 is a graph showing the relationship between the vehicle speed and the communication area of each part of the variable orifice valve. A cross-sectional view of the vr cotton line, Figure 8 is a graph showing the relationship between human power shaft torque and rack shaft thrust using vehicle speed as a parameter, and Figure 9 is a graph showing the relationship between power cylinder pressure and steering reaction force generation mechanism pressure using vehicle speed as a parameter. Figure 10 is a graph showing the relationship between reaction oil pressure and torsion bar torsion angle, Figure 1) is a graph showing the relationship between steering torque and reaction oil pressure, and Figure 12 is a graph showing the relationship between steering torque and torsion bar twist angle. Figure 13 is a graph showing the relationship between steering torque and steering angle at high vehicle speeds, and Figure 14 is a graph showing the relationship between steering torque and steering angle at low vehicle speeds. be. In the figure, 1 is a steering wheel, 2 is a steering shaft (input shaft), 4 is a steering angle ratio variable mechanism, 5 is an output shaft,
6 is a universal joint, 7 is a variable steering power steering device, 8 is a variable orifice portion, 9 is a rotary switching valve, I
O is a power cylinder, 1) is a steering reaction force generating mechanism, 32 is a torsion bar (elastic body), 33 is a rotational displacement generating means,
33c and 33d are plungers, and 33e to 33h are pressure chambers. Fig. 3 Fig. 4 1id Fig. 5 Fig. 8 Fig. 9 p-axis 1-a/7 THPO l)°7→decif”-hM Fig. 7 Fig. 1 O Fig. m Human Jl, 7
m 4lit W2 Topano 7 Fig. 13 Fig. 14 THII Yokochick Fν7

Claims (2)

[Claims] (1) An input shaft that steers a vehicle, a power device that generates a steering assist force in accordance with the steering torque applied to the input shaft, and a power device that generates a reaction force that resists the steering torque applied to the input shaft. a steering reaction force generation mechanism; a switching valve that controls the power unit and the steering reaction force generation mechanism according to the direction of steering torque applied to the input shaft; and detection that detects physical quantity elements that change depending on the running and steering conditions of the vehicle. and a selection means for selecting an operating ratio of the power plant and the steering reaction force generating device according to the detection result of the detection means, the power steering device comprising: an intervening means between the input shaft and the switching valve; A steering angle ratio variable mechanism comprising an inserted elastic body and a rotational displacement generating means for generating a rotational displacement with respect to the input shaft in the same direction as the steering direction in response to the reaction force of the steering reaction force generation mechanism. A power steering device characterized by comprising: (2) The power steering device according to claim 1, wherein the elastic body is a torsion bar.