JPH0418590B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a steering control device that controls power steering of front wheels when a vehicle turns and simultaneously controls a compliance steering mechanism according to steering torque.

1 and 2 are schematic plan views of a vehicle equipped with a rack and pinion type power steering device and having a semi-trailing arm type rear wheel suspension.

In the figure, 1 is the vehicle body, 2 is the front wheel, 3 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 hydraulic pressure adjustment valve of the power steering, 9 is the steering wheel, 10 is the power A steering hydraulic pump, 11 a reservoir tank for power steering hydraulic fluid, and 12 a hydraulic pipe. Further, 13 is a rear wheel, 14 is a rear wheel suspension member, and 15 is a differential gear housing. The member 14 and the housing 15 are fixed with bolts so that they move together. 16 is an insulator rubber of the rear wheel suspension member 14;
4 is the pin 17 via the insulator rubber 16
It is elastically fixed to the vehicle body 1 by. 18 is a differential gear insulator, and the differential gear housing 15 is elastically fixed to the vehicle body 1 by a pin 19 via the insulator 18. 20 is a semi-trailing arm,
21 is a drive shaft.

FIG. 2 is an explanatory diagram of the operation shown in FIG. 1. When the handle 9 is turned to the left, variable orifices a and b in the oil pressure regulating valve 8 are throttled and orifices c and d are opened, so that the oil in the power cylinder 6 is The oil pressure in the chamber e increases, the oil pressure in the oil chamber f decreases, and a force is applied to the rack gear 5 to turn the handle 9 to the left. Therefore, the steering force of the handle 9 is reduced. Note that when the handle 9 is turned to the right, variable orifices c and d are throttled and a and b are opened, so that the oil pressure in the oil chamber f increases and the oil pressure in the oil chamber e decreases, producing the same effect.

However, in such conventional suspensions, since the suspension and the vehicle body are fixed using rubber, when a left turn is made, for example, as shown in FIG. The insulator rubbers 16 and 18 are deflected by the side force F, and as a result, the rear wheel 13 is bent by the front wheel 2.
It can be cut in the direction shown by the opposite arrow E. This causes a problem of on-appliance steering, which causes the vehicle to become unstable when traveling at high speeds.

In order to solve these conventional problems, the present applicant has developed the apparatus shown in FIGS.
No. 99470) was proposed.

Various embodiments of this prior invention will be briefly described below with reference to FIGS. 3 to 8. In the figure, the same reference numerals as those mentioned above indicate equivalent parts.

First, to explain the configuration of Figures 3 and 4,
This is because hydraulic cylinder devices A, B, C, and D are provided between the suspension member 14 and the vehicle body 1 so that the rear wheel suspension member 14 rotates around the fixing pin 19 of the differential gear insulator 18. is installed.

and the left oil chamber e of the power cylinder 6 of the front wheel power steering and the 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 C are connected by a hydraulic pipe 25.

Therefore, as shown in FIG. 4, 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 increases.
oil pressure drops. Accordingly, the oil pressure of the hydraulic cylinder devices B and D connected to the oil chamber e by the hydraulic pipe 24 increases, and the hydraulic pressure of the hydraulic cylinder devices C,
A's oil pressure decreases. As a result, the insulator rubber 16 is deflected and the rear wheel 13 turns to the left. In other words, if the hydraulic force acting on the rear wheel 13 is larger than the side force F, the rear wheel 13 will turn to the left, and if the hydraulic force is smaller than the side force F, the originally generated compliance steer (rightward turning amount) will be reduced. reduce

As described above, according to the devices shown in FIGS. 3 and 4, the amount of cut in the rear wheels caused by the side force F is reduced, and stability during high-speed driving is achieved.

FIG. 5 shows a second embodiment, in which the insulator rubber 16 of the rear wheel suspension member 14 of the first embodiment is replaced with each hydraulic cylinder device A, B, C, D. Insulator rubber 2 with hollow oil chambers 26a provided on both sides of the rubber part
6 is provided at the installation position of the insulator rubber 16, and the hydraulic pipes 24, 25 are directly connected to each oil chamber 26a in the insulator rubber 26. The operation of this second embodiment is similar to that of the first embodiment, so a description thereof will be omitted.

Next, FIG. 6 shows a third embodiment, in which both ends of a power cylinder 6 of a power steering device that determines the steering angle of the front wheels 2 are connected to the vehicle body 1 via elastic bushes 27. At the same time, the outward protruding end of the piston rod 28a of the hydraulic cylinder device 28 fixed to the vehicle body 1 is connected to the bracket 6a protruding from the power cylinder 6, and the hydraulic pipe 24 is connected to the cylinder 28.
The hydraulic pipe 25 is connected to the oil chamber h of the cylinder 28.

In this case, as shown in FIG. 6, when the handle 9 is turned to the left, the oil pressure in the oil chamber e of the power cylinder 6 increases as described above, and the oil pressure in the oil chamber g of the cylinder 28 also increases; Since the oil pressure in f and h decreases, the power cylinder 6 moves to bush 2.
7 and move in the direction of arrow G,
By operating the handle 9 with respect to the power cylinder 6, the rack gear 5 also moves in the direction of arrow H.

In this case, the change in oil pressure (operating force of the steering wheel 9) is ahead of the change in the steering angle of the front wheels due to the operation of the steering wheel 9, so unlike the aforementioned compliance steer, the steering operation of the front wheels 2 occurs before the side force occurs. It increases by the amount of movement of the power cylinder 6. That is, the bush 27 can be deflected before the side force occurs to increase compliance steer and improve steering responsiveness.

FIG. 7 shows a fourth embodiment, which is different from the power cylinder 6 in the third embodiment.
Instead of being attached to the vehicle body via a bush 27, a pin 3a at the base of the knuckle arm 3 of the front wheel 2, which determines the axis of rotation of the front wheel 2 during steering, is moved by a hydraulic cylinder device 28.

That is, the ends of the piston rods 28a protruding from both sides of the hydraulic cylinder device 28 are connected to pins 30 provided on the vehicle body 1 via elastic bushes 29, and the pins 30 and 3a are connected to transformers. They are connected by a berth link 31, the hydraulic pipe 24 is connected to the oil chamber h of the cylinder 28, and the hydraulic pipe 25 is connected to the oil chamber g.

In this case, when the handle 9 is turned to the left, the rack gear 5 moves in the direction of arrow I, and the bush 29 is deflected, causing the piston rod 28a and transverse link 31 to move in the direction of arrow J. Also, the steering operation of front wheel 2 increases,
Steering responsiveness can be improved.

FIG. 8 shows a fifth embodiment, in which the hydraulic pressure supplied to the power steering mechanism is supplied to hydraulic actuation means (in this case, hydraulic cylinder devices A, B, C, and D).
A switching valve 32 that operates according to the vehicle speed is provided in the circuits 24 and 25 leading to the vehicle speed. That is, in the figure, 33 is a vehicle speed sensor, and 34 is an amplifier.

This is different from the first embodiment by using an electromagnetic directional switching valve 32, a vehicle speed sensor 33, and an amplifier 34 to switch the directional switching valve 32 at low speeds such as when parking in a garage, and turn the rear wheels 13 in the turning direction (in the steering direction of the front wheels). (in the opposite direction) to reduce the minimum turning radius.

However, since all of the conventional steering gear devices described above are configured to control oil pressure using one oil pressure control valve (hydraulic adjustment valve) 8,
In order to obtain a large power steering assist force at low speeds such as when stationary, it is necessary to increase the amount of oil generated by the hydraulic pump 10 at low speeds. As a result, the high oil pressure necessary for compact iron steering control cannot be obtained. Furthermore, if power steering hydraulic pressure is used that has a dead zone at small steering angles, sharp compliance steering control at small steering angles will not be possible.

In other words, if only one hydraulic control valve is used, 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, will be affected. There was a problem in that it was not possible to simultaneously satisfy the compliance steering control performance that reacts to the steering wheel.

In addition, there is an example of operating the rear wheels other than compliance steering control, as shown in Japanese Patent Application Laid-Open No. 54-159921, but since the rear wheels are controlled by detecting the steering angle of the front wheels, it causes a delay in control. It was hot.

The present invention was made in view of the problems of the conventional device, and includes a first hydraulic control valve that operates in response to steering torque to control power steering and has a dead zone for minute steering torque. , a second hydraulic control valve that controls a compliance steering mechanism that operates according to the steering torque to adjust vehicle behavior during turning operations, and uses at least one hydraulic power source to control both of these hydraulic control valves. It is an object of the present invention to solve the above problem by forming a first hydraulic circuit and a second hydraulic circuit independent of each other from the hydraulic power source.

The present invention will be explained below with reference to FIGS. 9 to 16. FIG. 9 shows an example in which the present invention is applied to the conventional device shown in FIG. 3, and the same reference numerals as those mentioned above in the figure are equivalent.

In this embodiment, in addition to the power steering hydraulic pump 10 (hydraulic source) in the conventional device shown in FIG. 3, a compliance steering control hydraulic pump 10' (hydraulic source) is provided, and a power steering hydraulic control valve 8 is provided. (First hydraulic control valve)
In addition, a compliance steer control hydraulic control valve 8' (second hydraulic control valve) is provided, and the hydraulic pump 1
The oil passage between the orifices a and c of the control valve 8 connected to the power cylinder 6 is connected to the power cylinder 6 via the hydraulic pipe 12.
At the same time, the oil passage between the orifices b and d is connected to the oil chamber f of the power cylinder 6 via the hydraulic pipe 12, thereby forming a first hydraulic circuit. Also, the oil passage between the orifices a and c of the control valve 8' connected to the hydraulic pump 10' is connected to the hydraulic pipe 2.
4 to the hydraulic cylinder devices B and D (compliance steering mechanism that adjusts vehicle behavior during cornering), and connects the oil passage between the orifices b and d of the control valve 8' to hydraulic pressure via the hydraulic pipe 25. A second hydraulic circuit is formed by connecting to cylinders A and C (compliance steer mechanism that adjusts vehicle behavior during cornering).

And hydraulic pump 10 for power steering
As shown in Fig. 10, the flow rate is reduced at high vehicle speeds, and the power steering hydraulic control valve 8 is provided with a dead zone S in the small steering angle range near straight-ahead travel, as shown in Fig. 11. establish.

Further, as shown in FIG. 12, the hydraulic pump 10' for compliance steering control has a characteristic that the flow rate increases at high vehicle speeds, and the hydraulic control valve 8' for compliance steering control has a characteristic that the flow rate increases as shown in FIG. 13. It is assumed that there is no dead zone S (see FIG. 11).

In addition, Figs. 14 to 16 show hydraulic control valves 8 and 8'.
6 in the figure shows an example in which the
a is a steering gear housing formed integrally with the power cylinder 6 of the power steering;
There is a crank gear 5 inside, which meshes with a pinion gear 7. Reference numeral 8a designates a valve housing that is integrally formed with the steering gear housing 6a and is commonly used for the hydraulic control valves 8 and 8', in which a hollow cylindrical valve body 8b is rotatably fitted together with the pinion gear 7.
A rotary valve body 8c is fitted inside. The rotary valve body 8c is adapted to rotate together with a valve shaft 8d that rotates as the handle 9 rotates, and the rotation of the valve shaft 8d is caused by a torsion bar 8e passing through the center of the valve shaft 8d and the rotary valve body 8c. The signal is transmitted to the pinion gear 7 via.

Therefore, when the steering force of the valve shaft 8d is applied by operating the handle 9, the torsion bar 8e is twisted due to the ground resistance of the tires, and as a result, the rotary valve body 8c which is interlocked with the valve shaft 8d is twisted.
A torsion bar 8e is installed between the valve body 8b and the valve body 8b.
A rotational displacement corresponding to the torsion of the is generated. 1st
5 and 16 show cross sections of the power steering hydraulic control valve 8 shown in FIG. 14, and the compliance steering control hydraulic control valve 8' has substantially the same structure.

As mentioned above, the valve body 8b and the rotary valve body 8c
When a rotational displacement occurs during this period, the pressure and direction of the oil sent from the hydraulic pump 10 are controlled, and the pressure oil is sent to the oil chamber e or f of the power cylinder 6, and the power assist is applied to the rack gear. 5, the wheel 2 is moved by the required amount.

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

When the vehicle is traveling straight, the hydraulic control valve 8 is in the state shown in FIG. 15, and the hydraulic oil from the pump 10 flows from the inlet port k through the groove on the outer periphery of the valve body 8b into the recess l around the valve body 8b. In the case of Fig. 15, the gap in the circumferential direction between the recess l on the inner circumference of the valve body and the rotary valve element 8c is the same and the circuit resistance is equal, so the hydraulic oil flows between the recess l on the valve body side and the recess on the rotary valve element 8c side. from the return port n through the outlet port p through the gap o between the rotary valve body 8c and the torsion bar 8e.
Return to reservoir tank 11. Therefore,
In this case, the left and right oil chambers e of the power cylinder 6,
Since no pressure difference is generated at f, the piston 6b remains neutral and does not move.

Next, if you turn the handle 9 to the right, the 16th
The result will be as shown in the figure. That is, since the rotary valve body 8c rotates in the direction of the arrow K, the recesses l and m communicate with each other, so that the oil pressure from the inlet port k acts on the oil chamber f of the power cylinder 6, and provides power assist to the piston 6b. , which acts as a force to move the rack gear 5 to the left. At this time, oil pushed out from the oil chamber e on the left side of the cylinder 6 enters the gap o via the port q and return port n, and returns to the reservoir tank 11 from the outlet port p.

Next, the operation of the apparatus of the present invention constructed as described above will be explained. In the embodiment shown in FIG. 9, when the vehicle is traveling straight, the steering wheel 9 is in the neutral position, so the piston 6b of the power cylinder 6 is also in the neutral position, and the vehicle is traveling straight.

Therefore, the hydraulic pump 10 has the characteristics shown in FIG. 10, the hydraulic pump 10' has the characteristics shown in FIG. 12, and the power steering hydraulic control valve 8 has the characteristics shown in FIG.
If the hydraulic control valve 8' for compliance steering control has the characteristics shown in FIG. 1 and the characteristics shown in FIG. 13, the flow rate of the hydraulic pump 10 is large at low vehicle speeds, so the power steering assist force is also large. Therefore, operations such as parking the vehicle become easier. In this case, since the speed is low, side force F (see Figure 2) hardly occurs, so
The flow rate of the hydraulic pump 10' is also almost 0, and the compliance steer control has almost no effect.

Next, at high vehicle speeds, the flow rate of the hydraulic pump 10 becomes small, so the assist force of the power steering becomes relatively small. Therefore, the disadvantage that the steering wheel wobbles when driving at high speeds is eliminated.

Further, at this time, the hydraulic control valve 8 has a dead zone S as shown in FIG. 11, so that the straight-line stability of the vehicle is not impaired in response to a slight angular displacement of the steering wheel.

However, when the steering wheel is turned at high speed, the side force F also increases, but in this case, the flow rate of the hydraulic pump 10' increases as shown in FIG. 12, so the compliance steering effect 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. 13, so it can immediately respond to the operation of the handle 9. Therefore, according to the present invention, compliance steering control can be effectively performed even at a minute steering angle.

Although FIG. 9 shows the present invention applied to the prior art shown in FIG. 3, the present invention can also be applied to the prior art shown in FIGS. 5, 6, 7, and 8. Needless to say. Furthermore, although the embodiment shown in FIG. 9 uses two types of pumps with different characteristics as hydraulic power sources, oil from one type of pump is transferred to each hydraulic control valve using a diversion valve (not shown). It is also possible to supply

In addition, the hydraulic control valve shown in FIGS. 15 and 16 is
Although this is an example of a rotary valve type, the present invention is also applicable to a spool valve type, a planet gear type,
It is also possible to use a conical rotary type valve.

As explained above, in the present invention,
a first hydraulic control valve that operates in response to steering torque to control power steering and has a dead zone for minute steering torque; and a compliance steer mechanism that operates in response to steering torque to adjust vehicle behavior when turning. A second hydraulic control valve for controlling is provided, and at least one hydraulic power source is used, and these two hydraulic control valves and the hydraulic power source form an independent first hydraulic circuit and a second hydraulic circuit, respectively. It has the excellent effect of ensuring a feeling of steering reaction force on the steering wheel when going straight at high speed, improving vehicle running stability through steering angle control, and enabling compliance steering control even when the steering angle is small. It will be done.

Furthermore, as shown in FIG. 14, it is advantageous in terms of weight, cost, and space if the two sets of hydraulic control valves are integrated with the steering gear housing.

[Brief explanation of drawings]

1 to 8 are plan views of a vehicle showing a conventional steering control device, FIG. 9 is a plan view of a vehicle showing a steering control device of the present invention, and FIGS. 10 to 13 are plan views of a vehicle showing a conventional steering control device. A characteristic diagram of a hydraulic pump and a hydraulic control valve, Fig. 14 is a sectional view showing an embodiment of the hydraulic control valve used in the present invention, Fig. 15 is a cross-sectional view of the hydraulic control valve, and Fig. 16 is an explanation of its operation. It is a diagram. 1...Vehicle body, 2...Front wheel, 3...Knuckle arm, 4...Side rod, 5...Rack gear, 6
...Power cylinder, 7...Pinion gear,
8... Hydraulic control valve for power steering (first hydraulic control valve), 8'... Hydraulic control valve for compliance steering control (second hydraulic control valve), 9... Handle,
10... Hydraulic pump for power steering (hydraulic source), 10'... Hydraulic pump for compliance steering control (hydraulic source), 11... Reservoir tank,
12... Hydraulic pipe, 13... Rear wheel, 14... Rear wheel suspension member, 15... Differential gear housing, 16... Insulator rubber, 17... Pin, 18... Differential gear Insulator, 19...Pin, 20...
Semi-trailing arm, 21... Drive shaft, 22... Hydraulic cylinder, 23... Hydraulic piston, 24, 25... Hydraulic pipe, 26... Insulator rubber, 27... Bush, 28...
...Hydraulic cylinder device, 29...Butsuyu, 30
...Pin, 31 ...Transverse link, 32
...Solenoid directional control valve, 33...Vehicle speed sensor, 3
4...Amplifier.

Claims (1)

[Scope of Claims] 1. A first hydraulic control valve that operates in response to steering torque to control power steering and has a dead zone for minute steering torque; a second hydraulic control valve for controlling the compliance steering mechanism that adjusts the behavior;
A steering control device characterized in that two hydraulic power sources are used, and a first hydraulic circuit and a second hydraulic circuit are formed independently from these two hydraulic control valves and the hydraulic power source. 2. A hydraulic source with a characteristic that the flow rate decreases as the vehicle speed increases is used in the first hydraulic circuit, and a hydraulic source that has a characteristic that the flow rate increases as the vehicle speed increases is used in the second hydraulic circuit.
The steering control device according to claim 1, wherein the steering control device is used in a hydraulic circuit. 3. The steering control device according to claim 1, wherein the first hydraulic control valve and the second hydraulic control valve are integrally formed with a power steering gear housing as a double valve.