JPH035349B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a power steering device that suppresses power assist for steering wheel operation when the vehicle speed exceeds a set speed.

(Conventional Device) The conventional device shown in FIGS. 1 and 2 is provided with three arms 2a at the tip of the steering shaft 2 of the handle 1.
A planetary gear 3 is provided for each of the. and,
This planetary gear 3 meshes with a sun gear 4 and a ring gear 5.

One end of a rod 6 is fixed to the sun gear 4, and the other end of the rod 6 is engaged with a piston 8 of a power cylinder 7. The rotation of the piston 8 is restricted, and the piston 8 is movable only in the axial direction.

Therefore, when the sun gear 4 and rod 6 rotate, the piston 8 moves in the axial direction.

A rack 8a is formed on the piston 8 thus constructed, and a sector gear 9 is engaged with this rack 8a. Further, the ring gear 5 is rotatably installed inside the main body 10 of the control valve C, and the ring gear 5 is provided with a connecting pin 11.
It is inserted into the spool 12 of. Both ends of this spool 12 face reaction force chambers 13 and 14, and these reaction force chambers 13 and 14 are connected to a port 15 of a solenoid valve S.

This solenoid valve S normally maintains the illustrated closed position and has a port 16 communicating with the pump P;
Communication with the port 15 communicating with the reaction force chambers 13 and 14 is cut off, and this port 15 is connected to the tank T.
Connect to. Then, when the solenoid valve S is switched to the open position, the ports 16 and 15 are communicated, and pressure oil from the pump P is guided to the reaction chambers 13 and 14.

A control circuit 17 is connected to the solenoid valve S thus constructed.
is connected to the speed sensor 18, and the speed sensor 1
When the speed detected at step 8 is equal to or higher than a set value, the solenoid valve S is switched to the open position.

If the handle 1 is now held in the neutral position, the spool 12 will also be held in the neutral position shown.

When the spool 12 is held at this neutral position, pressure oil flowing from the pump P into the control valve C via the flow path 19 is transferred to the spool 12.
Returns directly to the tank T via an annular groove 20 formed on the main body side → an annular recess 21 formed on the main body side → a flow path 22.

When the vehicle speed is below the set speed, when the steering wheel 1 is switched to the left or right, the ring gear 5
rotates to switch the spool 12 to either the left or right side. When the spool 12 is switched in this manner, one of the communication ports 23 and 24 communicating with the left and right chambers 7a and 7b of the power cylinder 7 communicates with the flow path 19, and the other communicates with the flow path 22.

Therefore, the piston 8 of the power cylinder 7 is moved by hydraulic pressure and turns the sector gear 9, so that the steering wheel operation becomes easier due to the power assist.

On the other hand, if the vehicle is running at a speed higher than the set speed, the speed sensor 18 detects the speed and the control circuit 17 sends a signal to switch the solenoid valve S to the open position. .

When the solenoid valve S is switched to the open position, pressure oil from the pump P flows into the reaction chambers 13 and 14. When pressure flows into the reaction force chambers 13 and 14, the spool 12 is pressed from both sides to maintain the neutral position shown, and the movement of the spool 12 is restricted by the hydraulic pressure.

Therefore, if you turn handle 1 in this state,
The sun gear 4 rotates without the ring gear 5 rotating. When the sun gear 4 rotates, the piston 8 is moved according to the pitch of the screw at the tip of the rod 6, and the sector gear 9 is rotated. In other words, it becomes a state of manual steering with power assist stopped.

In this way, in the conventional device, when the speed exceeds a certain set speed, the power assist is stopped and the operation is performed manually, and when the speed is below the set speed, the operation is performed using the power assist.

Therefore, with this conventional device, for example, if the steering wheel is operated while the vehicle is increasing speed, and the vehicle speed exceeds the set speed during the operation, the steering wheel suddenly becomes heavy. As a result, there was a problem with turning the steering wheel too late.

Also, if you are driving at a speed higher than the set speed and turn the steering wheel while decelerating, and the vehicle speed drops below the set speed while operating the steering wheel, the steering wheel will suddenly become lighter and there is a danger of turning the steering wheel too much. It was hot too.

In consideration of this point, it is conceivable to maintain the original steering state during steering operation despite changes in vehicle speed, and then switch the steering state after the steering wheel is turned.

However, even with this method, for example, in running conditions such as slalom where the steering wheel is continuously reversed, the problem of over-turning the steering wheel or turning the steering wheel too late cannot be solved.

This is because in this case, as soon as the steering wheel is turned, it must be turned in the opposite direction, but when turning the steering wheel in the opposite direction, the operating force changes suddenly.

(Objective of the present invention) The present invention maintains the original steering state despite changes in vehicle speed while operating the steering wheel, and after some time has elapsed after turning the steering wheel. To provide a device capable of stable operation even in running conditions such as slalom by switching from manual steering to power steering or from power steering to manual steering.

(Embodiment of the present invention) FIG. 3 shows a first embodiment, and in this first embodiment, the configuration of the hydraulic system itself is the same as the conventional one.

That is, when the solenoid valve S is in the illustrated position, the reaction force chambers 13 and 14 are connected to the port 15.
It communicates with tank T via.

In this state, when the handle 1 is turned, the ring gear 5 rotates, and the connecting pin 11 causes the ring gear 5 to rotate.
The spool 12 is switched to either the left or right side. When the spool 12 is switched in this way, the pressure oil from the pump P is transferred to either the left or right chamber 7 of the power cylinder 7.
a or 7b, and enters the power steering state.

Moreover, when the solenoid valve S is switched to the open position, the pressure oil from the pump P flows into the reaction force chambers 13 and 14, so even if the handle 1 is turned, the spool 1
2 does not move, resulting in manual steering as described above.

In such a device, the handle 1
A rotation angle sensor 26 for detecting the rotation angle of the steering wheel 1 is connected to the steering shaft 25 of the vehicle.

Note that instead of this rotation angle sensor 26, a torque sensor 27 that detects the steering force of the steering wheel, a displacement sensor that detects the stroke position of the piston 8 of the power cylinder 7, or a wheel angle (actual angle), A sensor or the like that detects the lateral acceleration of the vehicle may be used, and in short, any sensor may be used as long as it can detect whether or not the vehicle is being steered.

The signal detected by such a sensor is
It is input to the I/O section (interface) 28, but this interface
A speed signal from a speed sensor 29 connected to the crankshaft or drive shaft is also input.

Each signal input to the interface 28 in this manner is sent to the discrimination circuit 30. The discrimination circuit 30 controls the solenoid valve S based on the steering signal θ and the vehicle speed signal V.
The specific control is as shown in the timing chart of FIG.

That is, when the vehicle speed determined by the determination circuit 30 is less than the set speed, the solenoid valve S
is held in the closed position to maintain power steering.

When the vehicle speed exceeds the set speed from this state, the speed signal is determined by the determination circuit 30, and the solenoid valve S is switched to the open position to enter the manual steering state.

At this time, when the handle is operated, the operation signal is input to the discrimination circuit 30.

With the operation signal being input in this manner, even if the vehicle speed falls below the set speed, the solenoid valve S remains in the open position due to the output signal of the discrimination circuit 30.

Therefore, even if the vehicle speed changes from above the set speed to below the set speed during steering, the manual steering state is maintained.

Then, when the handle is returned to the neutral position again, the solenoid valve S is switched by the end signal of the steer rib.
The operation timing is slightly delayed.

That is, the discrimination circuit 30 is equipped with, for example, a controller having a time setting function, and is configured to switch the solenoid valve S to the closed position after a certain period of time has passed after the end of steering.

Therefore, for example, when the steering wheel is switched to one side and then immediately reversed in driving conditions such as slalom, the solenoid valve S remains in the open position, so the manual steering condition continues. .

Then, after a certain period of time has passed after returning the handle to the neutral position, solenoid valve S
switches to the closed position, resulting in power steering.

When the vehicle speed exceeds the set speed in this power steering state, the solenoid valve S is switched to the open position.

However, even in this case, while steering is in progress, the solenoid valve S remains in the closed position, and after a certain period of time has elapsed after the power steering ends, the solenoid valve S is switched to the open position.

Therefore, as described above, in a running state such as slalom, the solenoid valve S is not switched and the original steering state is maintained.

Note that the reference numeral 31 in the figure is an amplifier circuit.

FIG. 5 shows a second embodiment. This second embodiment differs from the first embodiment in that the reaction chambers 13 and 14 formed in the control valve C are sealed by a solenoid valve S. , the spool 12 is oil-locked.

That is, this solenoid valve S forms a port 32 that communicates with one reaction force chamber 13 and a port 33 that communicates with the other reaction force chamber 14, and also connects these ports 32 and 33 with the tank T. A port 34 is formed.

When the solenoid valve S is de-energized, it maintains the open position shown in the figure, but when it is energized, the plunger 35 protrudes and maintains the closed position, which closes the tank port 34.

Therefore, when the plunger 35 protrudes and the tank port 34 closes, the reaction chambers 13 and 14 are oil-locked and the spool 12 is held at the neutral position shown, resulting in a manual steering condition.

Other configurations and control mechanisms are the same as those in the first embodiment.

The third embodiment shown in FIG. 6 is applied to a rack and pinion type steering device.

That is, in this third embodiment, a pinion shaft 38 that rotates integrally with the handlebar 1 is engaged with a rack that is connected to a steering arm 37 of an axle via a tie rod 36.

Although the rack is not shown, it is provided in a direction perpendicular to the pinion shaft 38.

The pinion shaft 38 thus constructed is supported so as to be movable in parallel along the rack a predetermined distance in the direction of the arrow 39. Furthermore, a drive lever 40 is provided around the pinion shaft 38 so that the drive lever 40 swings about a fulcrum 41 when the pinion shaft 38 moves in the direction of the arrow 39.

A control valve C is provided so as to be orthogonal to this pinion shaft 38, and a connecting pin 44 provided on the drive lever 40 is inserted into a spool 43 provided in a spool hole 42 of this control valve C. .

Therefore, when the pinion shaft 38 moves in the direction of the arrow 39, the drive lever 40 swings, and as the drive lever 40 swings,
The spool 43 is switched.

The spool 43 is provided with a rod 45 at one end, and a large diameter portion 46 is formed in the middle of the rod 45. This large diameter portion 46
is slidable in a partition hole 47 formed in the spool hole 42.

On both sides of this partition hole 47, a reaction force chamber 4 is provided.
8, 49, and both reaction force chambers 4
A press plate 50 is provided on each of the parts 8 and 49, and the press plate 50 is brought into pressure contact with the large diameter portion 46 by the action of a spring 51.

The reaction force chambers 48 and 49 formed as described above are connected to a solenoid valve S similar to that of the second embodiment. That is, one reaction force chamber 48 is connected to the port 32 of the solenoid valve S, and the other reaction force chamber 49 is connected to the port 33.

The tank port 34 of this embodiment is connected to the tank T via a communication hole 52 formed in the spool 43.
is in constant communication with

When the handle 1 is turned with the solenoid valve S in the open position, the pinion shaft 38 is displaced in the direction of the arrow 39 because the resistance on the easy side is large. Along with this displacement of the pinion shaft 38,
Since the drive lever 40, that is, the connecting pin 44 swings, the spool 43 moves in the direction in which the connecting pin 44 swings.

As the spool 43 moves, pressure oil from the pump P flows into one chamber of the power cylinder 7, and the other chamber communicates with the tank T.

Therefore, a power-assisted steering state is established.

On the other hand, when the solenoid valve S maintains the closed position, the reaction force chambers 48 and 49 are oil-locked. Therefore, even if the steering wheel is turned, the spool 43 is not switched and only the pinion shaft 38 is rotated, resulting in a manual steering state.

The control mechanism in this third embodiment is as follows:
This is similar to the first embodiment, and therefore, control can be performed in accordance with the operating state of the steering wheel and the vehicle speed.

FIG. 7 shows a fourth embodiment, and the mechanism of the control valve C is the same as that of the first embodiment.

However, in this fourth embodiment, the structure of the solenoid valve S is different from that in the first embodiment.

That is, when the solenoid valve S is in the closed position shown in the figure, it allows the reaction force chambers 13 and 14 to communicate with each other, and also communicates the reaction force chambers 13 and 14 with the chambers 7a and 7b on both sides of the power cylinder 7. I'm trying to block it.

Therefore, in this state, both reaction force chambers 13,1
4 are completely in communication, the volume of one reaction force chamber decreases as the spool 12 moves, but
The oil corresponding to the decreased volume flows into the other reaction force chamber whose volume has been expanded. In this case, the movement of the spool 12 becomes smooth and a power steering state is established.

When the spool of the solenoid valve S is switched to the left in the drawing and held in the open position, communication between both reaction force chambers 13 and 14 is cut off, and one reaction force chamber 13 is connected to the right chamber 7b of the power cylinder 7. The other reaction force chamber 14 communicates with the left reaction force chamber 7a.

Therefore, when the handle is turned in this state, a hydraulic reaction force is applied against the movement of the spool 12, giving the handle an appropriate amount of resistance to turning the handle.

Also in this fourth embodiment, the control mechanism is as follows:
This is similar to the first embodiment, and therefore, control can be performed in accordance with the operating state of the steering wheel and the vehicle speed.

The fifth embodiment shown in FIG. 8 has a control valve C of the same type as that of the third embodiment, and a solenoid valve S of the same type as that of the fourth embodiment.

Therefore, when the solenoid valve S is in the closed position shown, both reaction force chambers 48 and 49 communicate with each other, while when the solenoid valve S is held in the open position, each reaction force chamber is connected to the power cylinder. It communicates with the left and right chambers of 7.

In other words, in this fifth embodiment as well, by controlling the solenoid valve S, control can be performed in accordance with the operating state of the steering wheel and the vehicle speed.

In each of the above embodiments, the solenoid valve S
The control mechanism for controlling is all the same and performs the control shown in the timing chart in FIG.

(Structure of the present invention) The structure of the present invention includes a control valve equipped with a spool that switches based on input rotation from a handle, and selectively supplies pressure oil to a power cylinder connected to a wheel via this control valve. On the other hand, a sensor is provided to detect the speed of the vehicle or engine, and when the detected speed is higher than a set speed, the spool is restrained in a neutral position or a hydraulic reaction force is applied in the direction of movement of the spool. In a power steering device equipped with a means for adding, during steering wheel operation, the switching operation of the constraining means or the adding means is stopped, and after a certain period of time has elapsed after the completion of the steering wheel operation is detected, The present invention is characterized in that it is provided with a control means for switching the restraining means or the addition means.

(Effects of the Invention) Since the present invention is configured as described above, even if the vehicle speed changes during steering operation, the steering resistance does not suddenly change.

Moreover, the operating resistance does not change even when the steering wheel is reversed during driving conditions such as slalom.

Therefore, stable steering operation is always possible.

[Brief explanation of drawings]

1 and 2 are a schematic configuration diagram and a partial configuration sectional view, FIG. 3 is a configuration sectional view showing a first embodiment of the present invention, FIG. 4 is a control timing chart thereof, and FIG. 8 are sectional views of the structures of the second to fifth embodiments. 1...Handle, 7...Power cylinder, C...
...Control valve, 12,43...Spool, 13,14,48,49...Reaction force chamber.

Claims (1)

[Claims] 1 Equipped with a control valve equipped with a spool that switches based on input rotation from the steering wheel, and selectively supplies pressurized oil to the power cylinders linked to the wheels via this control valve, while also detecting the speed of the vehicle or engine. In a power steering device, the power steering device is provided with a sensor that controls the spool, and that when the detected speed is equal to or higher than a set speed, the spool is restrained in a neutral position or a hydraulic reaction force is applied in the direction of movement of the spool in response to a steering wheel operation. , a control means for stopping the switching operation of the restraining means or the additional means during the steering wheel operation, and switching the restraining means or the additional means after a certain period of time has elapsed after detecting the end of the steering wheel operation; A power steering device equipped with