JPS5923775A - Auxiliary steering device for rear wheels - Google Patents

Abstract

PURPOSE:To enhance stability and safety in turning of a running car by changing the deviational angle of rear wheels, being operated by an actuator to drive the trunk rod and thereby making constant the cornering performance when the car runs turning. CONSTITUTION:Signals given from a front-wheel load sensor 1 and a rear-wheel load sensor 2 are added with a signal from a sideways acceleration sensor 3, and the sum obtained is entered into a control map 53. This control map 53 is stored in memory so that its ROM outputs the rear-wheel steering angle in correspondence with the specified front-axle load ratio and the sideways load applied to the car body, and the ROM is so arranged that the optimum steering angle according to signals from operational circuits 51 and 52 can be read. A solenoid-operated control valve 6 is driven in accordance with the output from the control map 53, and an actuator 7 is driven for a certain specified stroke to give the rear wheels 8 a specific steering angle theta.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a rear wheel auxiliary steering system that can maintain the cornering characteristics of an automobile in a constant state regardless of changes in driving conditions.

The cornering characteristics of an automobile change depending on conditions such as the steering load, the front axle load ratio determined from the front wheel load and the rear wheel load, and the turning speed. For example, even if a car has optimal cornering characteristics with one driver on board, two or three
When a person gets on board and the front axle load increases, the steering wheel tends to deviate outward from the predetermined curved line even if the steering wheel is turned by a predetermined angle.
t, that is, understeer becomes stronger, and when the rear axle load increases, the rear wheels slip, and the tendency for understeer becomes weaker.

Conventionally, in response to changes in driving conditions, changes in the rear axle's wheel alignment 1 (axle adjustment for Ritz 1 - axle vehicles, toe change for independent suspension vehicles) are used to respond to changes in loading conditions. Although it is possible to suppress the influence of cornering characteristics to some extent, the suppression effect is determined by the arrangement of the suspension links, so it is not possible to obtain desirable cornering characteristics under all loading conditions.

The purpose of the present invention is to adjust the direction of the rear wheels according to driving conditions.
The purpose of the present invention is to provide a rear wheel auxiliary steering system that provides stable cornering characteristics at all times.

For this reason, the configuration of the present invention includes load sensors installed in the front wheel suspension structure and v:/wheel support structure, respectively, and the front axle I'IFi weight and the rear axle weight based on the signals from the pair of load sensors. A logic circuit that calculates the front axle load ratio to the load, a lateral acceleration sensor installed in the center of the vehicle body, an actuator that drives the track rod connected to the knuckle arm of the left and right rear wheel suspension, and the actuator. It is equipped with an electromagnetic switching control valve that controls the electric fit 1,7J switching control valve, and a control device that controls the hydraulic circuit of the electric fit 1,7J switching control valve, and the control device is determined by the front axle load ratio and lateral acceleration. The vehicle is driven by a specific signal and the angle of the rear wheels operated by the actuator is changed to keep the cornering characteristics substantially constant during cornering.

To explain the present invention based on an embodiment, as conceptually shown in FIG. A MW sensor 2 and a lateral acceleration sensor 3 are provided at the center of the vehicle body. Then, using the detection signals of these sensors 1, 2, and 3 as input, outputs that meet predetermined conditions are applied to the vS magnetic switching control valve 0, which is controlled by the hydraulic circuit from the hydraulic pump 5. Drive the actuator 7 and
The vehicle is configured to control the direction of the rear wheel 8 by the driver 7.

In the case of an independent suspension mechanism of stocks 1 to 14, load sensors 1 and 2 rotatably support the spring seats 12 of stocks 1 to 14 and the struts 14, as shown in FIG. A known strain gauge 11 is interposed between the bearing 19 and the bearing 19.

The spring seat 12 supports a coil spring 13 surrounding the stocks 1 to 14 between the spring seat 12 and a spring seat fixed to the wall of the cylinder (not shown).

The bearing 19 is abutted against and supported by the strut mount 15 via the mount rubber 20, and the strut mount 15 is fastened to a portion 501 provided on the vehicle body 16 with the pins 1 to 18.

The detailed description of such a suspension mechanism is the same as that of the rear wheel suspension 11 shown in FIG. 3.4, which will be described later.

The lateral acceleration sensor 3 is, for example, a box fixed to the car body that supports a car with a spring so that it can move in the lateral direction of the car body, and electrically detects the movement of the plow. Since it is well known, it will not be described in detail.

The rear wheel suspension mechanism for mounting the rear wheel 8 is constructed as shown in FIG. 3-4. The shock absorber is supported by a strut mount 15 against the vehicle body, and the strut 14 extending from the piston disguised inside the cylinder 42 is connected to the spring connected to the mount 15 and fixed to the cylinder 42. A spring 1 is installed between the seat 43 and a spring seat supported below the strut mount 15.
It is constructed by interposing 3. A C-shaped knuckle 34 is connected to the lower end of the cylinder 42, and the lower end of the knuckle 34 is connected to the tip of the lower link 32 with a ball joint. The base end portion of the lower link 32 is supported by the vehicle body with a pin extending in the front-rear direction.

A knuckle arm 35 extends rearward from the knuckle 34, and a ball joint 38 is attached to the end of the knuckle arm 35.
are connected, and the left and right rods 1 to 37 are ball joints 39.
They are connected to each other by a center rod 36 via which the center rod 36 is driven in the axial direction by the actuator 7.

In the Acju J-7, a piston is fitted inside the cylinder 7a to define a liquid space on both ends, and the screw! A rod 7b connected to the hem extends from the cylinder 7a, and is connected to the center rod 36. A cylinder 78 is fixed to the vehicle body, and hydraulic pressure is selectively introduced into one of the hydraulic chambers.

A spindle is connected to the back or outer surface of the front wheel 34, and the rear wheel 8 is connected to the spindle along with the brake disc 41.
(Fig. 4) is supported. A trailing link 33 extending forward is connected to both ends of the lower link 32, and its tip end is connected to the vehicle body, thereby regulating the position of the knuckle 34 in the front-rear direction. In addition, in order to maintain a balance between the vertical movements of the left and right rear wheels, the center part of the stabilizer rod 45, which is bent into a U-shape, is rotatably supported toward the vehicle body by a bracket 1-44, and both ends of the stabilizer rod 45 are connected to the lower link. It is connected to a column 46 that projects upward from 32 .

As shown in FIG. 5, the control device 4 controls the front axle load sensor 1.
The detection signal of the rear axle load sensor 1 and the rear axle load sensor 2 is added to the arithmetic circuit 51, where a signal (M) corresponding to the curved axle load ratio is created and added to the control map 53. From the detection signal from the load sensor 2, the arithmetic circuit 52 generates a signal corresponding to the vehicle body ?7jl<total fl[> at 19, which is multiplied by the signal from the lateral acceleration sensor 3 to produce a signal corresponding to the lateral load applied to the vehicle body. Add a signal to control map 53.

The control map 53 uses a microcomputer, for example, and has a control map stored in its ROM to obtain a rear wheel steering angle corresponding to a predetermined front axle load ratio and a lateral load applied to the vehicle body, and is calculated from this RON4. The optimum steering angle corresponding to the signal from the circuit 51 and the signal from the arithmetic circuit 52 is read out. Then, the electromagnetic switching control i10 valve 6 is driven by the output from the control map 53, the actuator 7 is driven in a predetermined stroke from 1 to a predetermined stroke, and a predetermined steering angle θ is given to the rear wheels 8.

The control ffl+map 53 is created as follows. In other words, as shown in Fig. 6, the larger the lateral acceleration O generated on the car body due to centrifugal force when the car is turning, the more the line 6 in Fig. 6 increases.
1, the deviation from the predetermined turning radius (the ratio R/R of the actual 81e turning radius R to the predetermined turning radius RO)
o) is large, but when the optimum cornering characteristic for one occupant is not shown by plug 61, when the front axle load ratio becomes large with respect to the cornering characteristic for parking, as shown by line 62, When the front axle load ratio changes and the front axle load ratio decreases, the characteristics shown by the line 63 can be obtained experimentally. In response to such changes in load ratio, the rear wheels are always steered to improve the cornering characteristics shown by line 61 by 1q, but when the rear wheels are not steered, roll steer of the rear wheels, that is, when turning ! ■It is experimentally determined that when the body leans, the rear wheels are substantially deflected due to a one-to-one change or axle steering.

That is, under the operating condition shown by reference tfA61 in FIG. 6, the roll steer of the rear wheels with respect to the lateral acceleration Q is shown by the line 64 in FIG. The arrangement of the links of the suspension cushion can be varied to obtain cornering characteristics as shown by glands 65 and 66. The degree of roll steer is the wheel roll angle of 1°.
It is expressed as the steering angle per hit.

Based on the cornering characteristics described above, if the rear wheel roll steer is controlled to an appropriate value by external force, the line 61.6
A constant cornering characteristic as shown by 4) is provided.

It can be seen that in order to obtain such cornering characteristics, the roll steer of the rear wheels should be changed as shown by the line 67 in response to changes in the curved axis load ratio, as shown in FIG.

The above conditions apply when the vehicle body load is constant, but if the vehicle body load increases due to a change in the number of passengers, the roll angle of the rear wheels (proportional to the product of the vehicle body load and lateral acceleration Q) also increases. It is represented by a group of lines 68 with the steering angle θμ roll steer φ to be given to the wheels as a parameter.

Next, to explain the operation of the device of the present invention as described above, in FIG. A signal corresponding to the steering angle θ and a signal corresponding to the roll angle of the rear wheels are given to the operational circuit 52, and based on these signals, a signal corresponding to the steering angle θ stored in the control map 53 is weighted. The hydraulic fluid is supplied to the switching control tall valve 6, the hydraulic fluid is supplied from the hydraulic pressure source to the actuator 7, the actuator 7 is driven by a predetermined stroke, and the track rod 3
6.37, knuckle 34 is this knuckle arm 3
5. Spherical phase with the lower link 32; the hand rotates horizontally around the center, and the direction of the rear wheel 8 is changed.

When the direction of the rear wheels 8 reaches a predetermined steering angle θ, the electromagnetic switching control la valve 6 moves in conjunction with the movement of the rod 7b.
The hydraulic circuit is cut off and the actuator 7 is held in that position.

As the vehicle finishes turning, the signal from the lateral acceleration sensor 3 becomes O, and the output from the control map 53 also becomes O. Correspondingly, the position of the electric/polar switching control valve 6 changes.
The actuator 7 is returned to the neutral position 11, and the inclination of the rear shaft 8 is returned to the straight direction.

Since the present invention is configured as described above, the erotic loading line (
It is possible to obtain a constant cornering characteristic regardless of the vehicle's driving condition and driving conditions, and to always have a safe and easy-to-operate cornering performance, which improves the stability and safety of the vehicle's cornering operation. I can do it.

As mentioned above,! In the embodiment, the front axle load sensor 1 and the rear axle load sensor 2 are interposed between the slide 1 of the suspension mechanism and the small body, but the present invention is not limited to this configuration. As shown in FIG. 10, an arm 71 is connected to the medium heat portion of the stabilizer rod 45, a rod 72 is connected to the tip of the arm 71, and an excitation fit coil and a detection coil surround the rod 72 fixed to the vehicle body. 73 and stabilizer live rod 45
The amount of displacement of the rod 72 based on the change in torsion is 111'
By the detection coil 73 described in I? (b) The displacement of the rod 72 may be detected electrically, or the displacement of the rod 72 may be detected using a potentiometer. In addition, when a hydropneumatic type shock absorber is used as a suspension mechanism shock absorber, changes in the sealed liquid pressure or gas pressure, or struts 1 to 1.
Any distance or height change between the mounts 1-15 and the knuckles 4 may be electrically exposed.

Further, in the present invention, the rear wheel steering angle is manually selected. ”
;If the sea urchin grows up, you can park it in the garage at low speed or move closer to the side.)2
The turning radius can be reduced by increasing the steering angle of the wheels to 1 for i'p.

Furthermore 1. Cornering characteristics related to the operating angle of the steering wheel and the traveling speed of the vehicle are added to the li control map 53,
By controlling the steering angle of the rear wheels in relation to these conditions, even more stable cornering performance can be achieved.

[Brief explanation of the drawing]

Figure 'I is a schematic configuration diagram of the rear wheel auxiliary steering system according to the present invention, Figure 2 is a side view showing an example of the shaft steering wheel υ, and Figure 3 is a perspective view of the rear wheel auxiliary steering system. Figure 4 is a rear view of the same, Figure 5 is a block diagram of the control I device, Figures 6, 7, 8 and 9 are the control map shown in Figure 5. FIG. 10, an explanatory diagram for determining a characteristic diagram, is a side view of a partially modified embodiment of the present invention. 1: Front axle load m sensor 2; Rear axle load m sensor 3: Lateral acceleration sensor 4: trll■0 greasing 5: Hydraulic pump 6: Electric (1) switching i: lJ control valve 7; Actu 1-Y
8: Rear axle 14: Straff 1-rod 16: Vehicle body 3
2: [1 early link 33: Trailing link 34:
Knuckle 35: Knuckle arm 36: Center rod 37: 1 ~ Rack rod 7I5 Stabilizer rod 51, 52: Operation circuit 53; Figure 9 Figure 110

Claims (1)

[Claims] A load sensor provided on each of the front wheel suspension tla structure and the rear wheel suspension separate structure, and the pair of loads ff! A linkage circuit that calculates the front axle load ratio between the front axle load and the rear axle load m from the signal from the rear axle, a lateral acceleration sensor installed in the center of the vehicle body, and a knuckle arm connected to the left and right rear wheels. It is equipped with an actuator that drives the L rack rod, an N... cut-off side control valve that controls the actuator, and a control device that controls the hydraulic pressure circuit of the frost-butt flame cut-off side control valve, The control device is driven by a specific signal determined by the front m ratio of the front axle and the lateral acceleration, and changes the deflection angle of the rear wheels operated by the actuator to approximately control the cornering characteristics during cornering. A rear wheel auxiliary steering device characterized by the fact that the steering remains constant.