JPS6092980A - Steering controller - Google Patents

Abstract

PURPOSE:To improve the steering stability in rainy weather by steering a rear wheel in the same direction to a front wheel when a weather sensor detects rainy weather, in the captioned apparatus by which the steering of the rear wheel is controlled by an oil pressure according to the steering of the front wheel. CONSTITUTION:When a steering wheel 9 is turned, a knuckle arm 3 is turned through a steering gear mechanism 7 by receiving an energizing force of a power cylinder 6, and a front wheel 2 is steered. At this time, right and left actuators 22 in pair are operated by the pressurized fluid corresponding to the steering force, and a rear wheel 13 is steered by the turn around a pin 19 of a rear-wheel suspension member 12. In this case, an oil-pressure feeding oil passage 27 and a drain oil passage 28 for a control valve 8' for controlling the pressurized fluid supplied and discharged from each acturator 22 communicate each other through an electric-current proportional flow-rate control valve 26. Said valve 26 is controlled by the output signal of a weather sensor 31 so that the rear wheel 13 is steered in the same direction to that of the front wheel 12.

Description

DETAILED DESCRIPTION OF THE INVENTION (Technical Field of the Invention) The present invention relates to a control device for a rear wheel steering device W that hydraulically controls the steering of the rear wheels in response to the steering of the front wheels.

(Prior Art and its Problems) A conventional rear wheel steering device of this type as shown in FIG. 1 is known from Japanese Patent Application Laid-open No. TL1357-99470.

In the figure, 1 is the heavy object, 2 is the front wheel, 8 is the knuckle arm, 4 is the side rod, 5 is the rack gear, 6 is the power cylinder of the power steering, 7 is the pinion gear, 8 is the curved pressure reservoir regulator of the power steering, 9 is the handle , 10 is a power steering 1 pressure pump, 11 is a power steering hydraulic oil reservoir tank, and 12 is a hydraulic pipe.

Further, 18 is a (It wheel), 14 is a rear wheel suspension member, 15 is a differential gear housing, and the member 14 and housing 15 are fixed with bolts and are made to be integrally thin. 16 is an insulator of the rear wheel suspension member 14. The rear wheel suspension member 14 is made of insulator rubber 16.
It is elastically fixed to the body 1 by a pin 17 via. 18 is the differential gear insulator,
The differential gear housing 15 is elastically fixed to the body 1 by a pin 19 via an insulator 18. 20 is a semi-trailing arm, and 21 is a drive shaft.

In this prior art, the in-suspension member 14 is rotated around the fixing point 19 of the differential gear insulator 18 in order to eliminate instability during high-speed driving due to the notch (compliance steer) effect caused by the side force when turning. In order to achieve this, a hydraulic cylinder device A r B r O+ D is installed between the suspension member 14 and the casing 1.

And the power cylinder 6 of the power steering for the front wheels
left oil chamber e and hydraulic cylinder device B.

D is connected by a hydraulic pipe 24, and the right oil chamber f of the power cylinder 6 and the hydraulic cylinder devices A and O are connected by a hydraulic pipe 25.

Therefore, when the steering wheel 9 is turned to the left, the oil pressure in the left oil chamber e of the power cylinder 6 of the power steering increases, and the oil pressure in the right oil chamber f decreases. Accordingly, the hydraulic cylinder system ff is connected to the oil chamber e by the hydraulic pipe 24.
The oil pressure of 1B and 1D increases, and the oil pressure of the hydraulic cylinder device olA decreases. As a result, the insulator rubber 16 is deflected and the rear wheel 18 turns to the left. That is, rear wheel 1
1. If the acting force due to hydraulic pressure is larger than the side force F acting on 8. Rear wheel 18 turns to the left, side force F
If the force exerted by the hydraulic pressure is small compared to the amount of force exerted by the hydraulic pressure, it acts to reduce the compliance steer (the amount of rightward turning) that would normally occur.

As mentioned above, with the conventional device shown in Fig. 1, the amount of cutting in the rear wheel caused by the side force F is reduced, and stability during high-speed driving is achieved. Since the hydraulic pressure is controlled by a control valve (hydraulic adjustment valve) 8, the amount of power generated by the hydraulic pump 10 is reduced at low speeds in order to generate a large power steering assist force 'f:rG at low speeds such as when stationary is being carried out. In particular, at high speeds where little assisting force is required, the generated flow rate is reduced so that the high hydraulic pressure required for compliance steering control is not sufficient. Furthermore, if a power steering hydraulic pressure with a dead zone provided at small steering angles is used, there is a problem in that it becomes impossible to perform sharp steering control at small steering angles.

In other words, depending on only one hydraulic control valve, the assist performance of power steering, which requires a large assist hydraulic pressure at low speeds and has a dead zone for minute steering torques, and the assist performance of power steering, which requires a large control hydraulic pressure at high speeds and has a dead zone for minute steering torques, are affected. There was a problem in that it was not possible to simultaneously satisfy the driver's steering control and illumination performance.

In order to solve the above-mentioned problems, the applicant has proposed a 64-component steering system as shown in FIG. 10 (hydraulic source), a hydraulic pump 10' (hydraulic source) for power steering control is provided, and a hydraulic control valve 8 for power steering (@I
In addition to the compliance steer control hydraulic control valve 1 8' (second curve pressure, '[iIl# valve)], orifices a and C of the flnJ control valve 8 connected to the hydraulic pump 10 are provided. The oil passage between is connected to the oil chamber e of the power cylinder 6 via the hydraulic pipe 12, and the orifice b,
The oil passage d14 is connected to the oil chamber f of the power cylinder 6 via a hydraulic pipe 12'ft to form a first hydraulic circuit. In addition, the 1lflJ control valve 8 connected to the hydraulic pump 10'
The oil passage between the orifices a and C of ' is connected to the hydraulic cylinder equipment ff1B and D via the hydraulic vibrator 24, and the ilI circuit between the orifice b and d of the control valve 8 is connected to the hydraulic cylinder unit via the hydraulic vibrator 25. It is connected to devices A and O to form a second hydraulic circuit.

@2 Hydraulic pressure shown in figure 1 tl? Ml s, 8'c, example +
+1, as shown in Figures 8 to 6, and 6 in the figure.
eL is a steering gear housing formed integrally with the power cylinder 6 of the power steering, and has a rack gear 5 inside, which meshes with the pinion gear 7. 8a
is a valve housing that is integrally formed with the steering gear housing 6a and is shared by the hydraulic +lJl control valves 8 and 8'.
A hollow cylindrical valve body 8b is rotatably fitted together with the pinion gear 7 inside, and a rotary valve body 8G is fitted inside this valve body r8b.

The rotary valve body 80 rotates together with the valve shaft and foot 8d which rotate as the handle 90 rotates, and the rotation of the valve shaft 8d is controlled by the valve shaft 8d.
d and is transmitted to the pinion gear 7 via a torsion bar 80 passing through the center of the rotary valve body 80.

Therefore, by operating the handle 9, the valve shaft 8
When a steering force is applied to d, the torsion bar 80 is twisted due to the tire's ground resistance, resulting in valve shirt) 8d
F between the rotary valve element 80 and the valve body 8b that interlock with the
- A rotational displacement corresponding to the twist of the jumper 8e occurs. 4 and 6 show cross sections of the power steering hydraulic control valve 8 of FIG. 8, and the compliance steering control hydraulic control valve 8' is also manufactured in substantially the same manner.

As described above, when a rotational displacement occurs between the valve body 8b and the rotary valve body 8C, the pressure and direction of the oil sent from the hydraulic pump 10 are controlled thereby, and the oil chamber e or f of the power cylinder 6 is controlled. The heavy wheels 2 are moved by the required amount via the rack gear 6 with power assist.

In other words, the movement of the valve shaft 8d is displaced according to the load on the tire, and the oil pressure increases accordingly, resulting in output.
At the same time, a force corresponding to the torsion angle of the torsion bar 8e is transmitted to the driver as a reaction force. Therefore, the driver can always feel the road reaction force depending on the load.

When driving straight through the city, the hydraulic control valve 8 is in the state shown in Fig. 4, and the operating surface from the pump 10 is in red bow).
k flows through the groove on the outer periphery of the valve body 8b and into the concave l on the side of the valve body 8b, but in the case of Fig. 4, the groove l on the inner circumference of the valve body and the rotary valve body 8C flow in the circumferential direction. Since the gap is the same and the circuit resistance is the same, the operating surface is the recess l on the valve body side and the recess m'f on the rotary valve body 80 side: From the return boat n, the gap between the rotary valve body 80 and the torsion bar 8e is 0. It returns to the reservoir tank 11 from outlet boat p via . Therefore, in this case, since no pressure difference occurs between the left and right oil chambers e and f of the power cylinder 6, the piston 6b remains neutral and does not move.

Next, when the handle 9 is turned to the right, the situation becomes as shown in FIG. That is, since the rotary valve body 8C rotates in the direction indicated by the arrow, the recesses l and m communicate with each other, so that the free pressure from the inlet hole k acts on the oil chamber f of the power cylinder 6, and the piston At this time, the oil pushed out from the oil chamber e on the left side of the cylinder 6 enters the gap O via the boat q and the return boat n, and enters the outlet boat. Return to reservoir tank 11 from p.

Next, the operation of the apparatus of the present invention constructed as described above will be explained. In the embodiment shown in FIG. 2, when the steering wheel 9 is in the neutral position when driving straight through the city, the power cylinder 6
The piston 6b is also in the neutral position +N and advances 1a within the city.

Then, as shown in FIG. 6, the power steering hydraulic control valve 8 is set to have a characteristic that the flow rate decreases at high speeds, as shown in FIG. No-e band S in the small steering angle range
will be established.

In addition, the i+h FJ- pump 10' for compliance steer control has a characteristic that the flow rate increases at high speeds, as shown in FIG. As shown, dead zone S
(See FIG. 7) If the characteristics are fleeting, the flow rate of the hydraulic pump 10 is large at low speeds, so the assist force of the power steering also becomes large. Therefore, operations such as putting the eye in the eye can be made easier. In this case, since the speed is low, almost no side force F is generated, so the hydraulic pump 10'
The flow rate is also almost 0, and the compliance steering wheel 1] control has almost no effect.

Next, at high speeds, the flow rate of the hydraulic horn 10 becomes small, so the assist force of the power steering becomes relatively small.Therefore, the disadvantage of the steering wheel wobbling during high speed driving is eliminated.

Further, at this time, the hydraulic control valve 8 has a dead zone S as shown in FIG. 7, so that the straight-line stability of the heavy vehicle is not impaired in response to minute angular displacements of the handlebar.

However, when the steering wheel is turned at crystal speed, the side force F also increases, but in this case, the hydraulic pump 10'
Since the flow rate increases as shown in FIG. 8, the compliance steer action also works strongly and reliably. Further, the hydraulic pressure control valve 8' for controlling the hydraulic pressure in this case has no dead zone as shown in FIG. 9, so it can immediately respond to the operation of the handle 9. Therefore, compliance steering control can be effectively performed even with a small steering angle.

In general, if the steering characteristics of a free vehicle are set to weak understeer or neutral steering characteristics, the response to steering in both directions will be improved, and the crispness during steering will be improved. In the state,
There is a problem in that the road surface grip performance of the rear wheels decreases, and if the above-mentioned characteristics remain unchanged, the characteristics become uneasy for the driver. JP-A No. 57-99470 takes some measures against this opening movement, but since uniform control is performed regardless of road surface conditions, it is sufficient to ensure maneuverability in rainy weather. I couldn't say that.

(Object of the invention) The object of the invention is to solve the above-mentioned opening movement.

(Structure of the Invention) The present invention is characterized in that the hydraulic pressure is controlled by a wiper switch, the output from a rain sensor such as a rain sensor, etc., and thereby the above-mentioned object is achieved.

(Embodiment of the Invention) FIG. 10 shows an example in which the present invention is implemented in the rear wheel steering device U shown in FIG. The solenoid of the attached control valve 26 is inserted in a bypass oil path 29 between an oil path 27 that supplies hydraulic pressure to the steering control hydraulic pressure control valve 8I and a drain oil path 28 from this control valve 8' to the tank 11. Wiper switch 81 to 80
A foot roller 82 is connected to F to send an input signal.

In this way, the pressure compensation type current proportional flow control valve 26 controlled by the input signal from the rain sensor such as the wiper switch 81 is connected to the pressure compensation type current proportional flow rate control valve 111 + the pressure supply curved path 27 and the drain oil path 28.
By inserting the oil pressure into the bypass oil passage 29 between the pump No. As a result, the hydraulic cylinder devices A, B, 0 . By increasing the oil pressure supplied to D, the steering characteristic of the heavy vehicle can be changed from a weak under-under characteristic A when the road surface is dry to a strong under-under characteristic B when the road surface is wet, as shown in FIG. That is, in rainy weather, the flow rate of the bypass oil passage 29 is reduced compared to that in sunny weather, the hydraulic pressure guided to the rear wheel steering device is increased, and the amount of steering of the rear wheels is increased.

In the embodiments described above, the case where the present invention is implemented in the Humpliance Steer rear wheel steering system has been described.
The present invention provides a servo i! which is controlled by an output signal from various types of rear sensors that hydraulically control the steering of the rear wheels in response to the steering of the front wheels. The present invention can also be implemented in a rear wheel steering system in which the steering of the rear wheels is hydraulically controlled through the ll structure.

Furthermore, in this embodiment, the rear wheels are steered in the same direction as the front wheels when the front wheels are steered, and in rainy weather the rear wheels are steered in the same direction as the front wheels.
As described above, the case where the amount of steering is relatively increased is that the rear wheels are not steered on sunny days, but the rear wheels are steered in the same direction as the front wheels only when turning on rainy days, resulting in understeer characteristics. It is also possible to control it so that it is strengthened.

(Effects of the Invention) According to the present invention, the control hydraulic pressure of the rear wheel steering system is controlled by the output signal from a rain sensor such as a wiper switch or a raindrop sensor, which generates a signal during rainy weather. The effect of reducing the driver's anxiety by changing the steering characteristic on the east side to the Tsukuda under-characteristic in response to the wet condition can be obtained.

[Brief explanation of drawings]

Figure 1 is an enclosure diagram of a conventional M-type snake control device, and Figure 2 is an enclosure diagram of a conventional
Figure 8 is a vertical sectional view showing the detailed structure of the hydraulic flilJ control valve shown in Figure 2. Figure 4 is a diagram of the hydraulic control valve shown in Figure 8. A cross-sectional view, FIG. 5 is an explanatory diagram of the operation of the M pressure control valve, FIGS. 0 to 9 are characteristic diagrams of the hydraulic pump and the hydraulic control valve, and FIG. 10 is a schematic diagram of the vehicle steering system according to the present invention. FIG. 11 is a characteristic curve diagram showing changes in steering characteristics according to the present invention. 1...Heavy body 2...Front wheel 8...Knuckle arm 4...Side rod 6...
・Rack gear 6...Power cylinder 7...Pinion gear 8...Power steering hydraulic control valve (first hydraulic pressure 1
(Control valve) 8'...Humpliance steering system (3)J bending pressure control valve (second hydraulic control valve) 9...Handle IO...Hydraulic pump for power steering (hydraulic source)
10'... Hydraulic pump for compliance steer control (hydraulic source) 11... Reservoir tank 12... Hydraulic pipe 18... Rear wheel 14,... Rear wheel suspension member 16... Differential gear housing 16.・Insulator rubber 17 ・Pin 18.6 ・Differential gear insulator 19...
Bin 20... Semi-trailing arm 21... Drive shaft 22... Hydraulic cylinder 28... Hydraulic piston 24.25... Hydraulic high 26... Pressure compensated current proportional flow control valve 27...・
Hydraulic supply oil path 28...Drain oil path 29...Bypass IDL path 80...Solenoid 81...Wiper switch 82...Controller. Patent applicant Nissan Motor Co., Ltd. Figure 1 Figure 2 Figure 6 Vehicle speed Figure 8 Vehicle speed Figure 7 Figure 9 Operation torque

Claims (1)

[Claims] L A rear wheel steering device that controls the steering of the rear wheels according to the steering of the front wheels using a hydraulic mechanism, which includes a rain weather sensor that detects rainy weather, and a rainy weather signal from the rainy weather sensor that operates,
iiJ A steering control device comprising a controller for driving a rear wheel steering device, and configured to control the rear wheels to be steered in the same direction as the front wheels in rainy weather.