JPS5893668A - Power steering gear - Google Patents

Abstract

PURPOSE:To forcibly reset a valve when the valve continues operating even though a neutrality signal is generated, by providing a position sensor for a control valve controlled by a microcomputer. CONSTITUTION:The control valve is operated by a solenoid 22, and has such a construction that ports A, B communicated to a power cylinder, a port P communicated to a pump and a port T communicated to a tank are changed over in accordance with the position of a spool 21. The spool 21 is provided with the valve position sensor 35 and is connected with a solenoid valves 31, 32 through logical circuits 38-40. When the spool 21 is deviated from a neutral position even though the neutrality signal is generated, the solenoid valve is opened to supply a hydraulic oil into a spring chamber 26 or 27, thereby forcibly resetting the spool 21. Accordingly, even when the valve is erroneously operated due to the presence of dusts or the like, the danger of continuing the operation of the power cylinder can be prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a power steering system for an automobile that reduces steering force by using mineral oil pressure.

The control pulp is switched by mechanically detecting the rotation of the input shaft connected to the normal / and power steering device wire and the handle. Pressure oil is selectively supplied to the arm cylinder located at the tip of the steering wheel, so that the steering link turns the direction of the wheel in proportion to the rotation of the input shaft.

Especially in the f-power steering system of automobiles.

To ensure safety, the tip of the input shaft is connected to the piston of the Nowawar cylinder via a goal screw assembly so that it can be operated even if hydraulic assist force cannot be obtained due to a failure of the hydraulic system. Mechanically connected.

By the way, the control pulp, which controls the direction of the pressure oil sent to the four-power cylinder by the rotation of the input shaft, is feedback-controlled in conjunction with the movement of the input shaft and the actual movement of the piston on the output side. Because of this, there are significant restrictions on its installation, and its placement is usually limited to areas such as where the input shaft connects to the arm arm cylinder. In addition, in order to perform such mechanical feed/four-wheel control, the structure of the control pulp has to be eliminated and complicated. In a nine-speed sensitive power steering device that always obtains the optimum steering force, the structure of the control pulp must be made even more elaborate, which results in poor maintainability and safety, and is also expensive. There was a drawback.

On the other hand, controlling the vehicle so that the optimum steering force can be obtained according to the driving conditions of the vehicle is essential to the comfort of the vehicle.

From the perspective of pursuing safety, there will be a strong demand for this in the future, so we developed the Nowawer Steering System, which uses a microcomputer to always obtain optimal steering force under a variety of driving conditions. It has been proposed by the applicant as Japanese Patent Application No. 19196-1983.

To explain this based on Figure 1,
An input shaft 2 connected to the input shaft 2 is connected to a piston 4 of a main hydraulic actuator 3.

In this case, the piston 4 is not shown as the input shaft 2? −Le・
The piston 4 slides inside the cylinder 3 depending on the rotational direction and speed of the input shaft 20 because the piston 4 is interconnected through the screw and screw assembly.

Two hooks 5 are provided on the side of the piston 4 (64), and these two
A sector gear 6 meshes with the gear 5, and as the piston 4 moves, a steering link (not shown) is driven via a pit inner gear 57 which is interlocked with the sector gear 6.

As the input shaft 20 inputs rotation, the piston 4 moves,
In order to assist this movement with hydraulic pressure, pressurized oil is selectively controlled and supplied from the pump P by the PS control pulp 9 to the eight oil chambers and 8B separated on both sides of the piston 4. The control pulp 9 is an electromagnetic pulp whose operation is controlled by a microcomputer 10 to which the rotational direction of the input shaft 20 and the rotational force of the rotational force are input, and the operation load on the output side is fed back.

Here, reference numeral 11 denotes a four-wheel sensor attached to the input shaft 2, which is constituted by a strain sensor for detecting the rotational force and direction of rotation by detecting the torsion of the input shaft 2. 12 [
Similarly, this is a magnetic pickup for detecting the rotation speed of the input shaft 20.

Then, these detection and ratio signals are each amplified.

Input interface 7 ace 14 with signal waveform processing function,
Through the arithmetic control unit 15 of the microcomputer IO
Enter.

The calculation control unit (CPU) 1M performs calculations based on these inputs, selects the stored value from the storage unit (ROM) 16 which stores the optimum value corresponding to the operating conditions in advance, and outputs it to the output interface 17. The signal is output to the control pulse f9 via the control pulse f9.

Pulp 9 is composed of a solenoid pulp, whose switching direction and amount are controlled based on input signals, and is sent to left and right oil chambers 8A and 8B of power cylinder 3)
Controls the amount of pressurized oil.

When operating the handle 1 to rotate the input shaft 2 in either direction, a reaction force proportional to the operating load applied to the input shaft 2 by the piston 4K of the cylinder 3 is generated.
This is about to be transmitted to the driver as a steering wheel operating force, but this operating force (rotational force and direction of rotation) is sensed by the digit load sensor 11 attached to the input shaft 2, and at the same time the input rotational speed is detected by a big alarm. f12 detects and inputs these to the microcomputer 10.

Since the optimal value corresponding to the input signal is preset in the storage unit 16, the arithmetic control unit 15 reads this value, performs predetermined signal waveform processing and amplification at the output interface 17, and outputs the control pulp 9. Enter.

Therefore, the pressure oil 9 sends the required amount of pressure oil to the oil chamber 8A or fi 8B of the power cylinder 30 in proportion to the magnitude and direction of the operating force. In this case, when the vehicle speed is low and the turning resistance of the wheels is large, the load sensor 11 detects that the torsion angle of the input shaft 2 is -large. , increases the hydraulic pressure supplied to the power cylinder 3, and when the handle rotation speed is high,
Correspondingly, the microcomputer 10 controls the output value so that the switching amount of the control pulp 9 increases so as to increase the amount of pressure oil fed.

As a result, an operation to move the piston 4 by the input shaft 2 is performed in the oil chamber 8A or 8B depending on the operating load.
The steering wheel is assisted by hydraulic pressure, so the steering wheel can be operated easily and with an appropriate operating feel.

On the other hand, when the handle 1 is fixed, the input shaft 2t
-The reaction force that tries to twist according to the operating load is reduced,
If the output value of the load sensor 11 is small, the control pulp 9 is accordingly returned to the neutral position via the microcomputer 10t, thereby stopping the supply of pressure oil to the arm cylinder 3. It will be done.

In other words, feed and electric inputs can be obtained at the same time, and when the input shaft 2 stops, the lower cylinder 3 also stops operating, and the wheels are held at that switching angle.

By the way, in this 9-power steering device, the PS control pulp 9 exists independently, so if the return to the neutral state is not performed smoothly due to dust in the hydraulic oil, the steering wheel will not return to the neutral state. A very dangerous situation occurs in which pressure oil is supplied to the power cylinder 3 even though it has been returned to the position.

The object of the present invention is to solve this problem, that is, to forcibly return the electromagnetic PS control to the neutral position when the handle is in the neutral position.

, the present invention introduces high pressure to the end of the pulp spool to forcibly move it to the neutral position when the PS control pulp is switched to ftL or one direction while the handle neutral position signal is being input. It is meant to bring you back.

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

In FIG. 2, the electromagnetic Ps control valve 9 is
The pulp is stored in the spool 20 in a freely sliding manner, and the end of the spool 21 is equipped with a solenoid (2201KI).
M'-I'2B is connected, and the spool 21 is switched from side to side.

When the pulp is placed in D2O, there is a high pressure 4-P on the hydraulic pressure side.
Sandwiching this, there are two low pressure ports (T) on the reservoir side, and oil chambers 8A and 8B of the Noah cylinder 3 located between them.
K connection operating ports A and B are formed, and the snottle 2
Three 2″ rings formed in 1Cs-Cs,
In the neutral position shown in the figure, the high pressure port P operates and oil is returned to the low pressure port T, and when the spool 21 is switched to the right, pressure oil is operated from the high pressure port P. −
) to A (at this time, operating port B is connected to low pressure port T)
.

Conversely, when the spool 21 is switched to the left, the pressure oil from the high pressure port P is sent to the working port B (connected to the low pressure port T for working boats).

Spring chambers 27 and 27, in which neutral return springs 24 and 25 are interposed, are formed at both ends of the spool 21.

The spring chambers 26 and 27 each communicate from the periphery of the spool 21 to the low-pressure side to prevent leakage, and do not prevent the spool 21 from moving to the left or right.

By the way, is the left spring chamber 26 working? - communicates with the spring chamber 2 on the right side via the pressure passage 29;
Is 7 working? - It communicates with port A via a passage 3o, and normally closed solenoid valves 31 and 32 are interposed in the middle of the passage.

The solenoid 22 has two coils 33A and 33B, and an excitation current from the microcomputer 10 (see FIG. 1) is supplied through enclosures 34A and 34B. For example, when the coil 33A is excited, the spool 21 moves to the left. Displaced,
When the coil 33B is excited, it is also displaced to the right.

On the other hand, a pulp position sensor 35 is provided to detect the movement of the lunoid 22, and this detection signal is input to an AND circuit 37.

Note that the pulp position sensor 35 outputs a high level signal 51'' when the pulp is not at the neutral position, and the output changes to 4-level 10'' at the neutral position.

Signal circuit 34A from microcomputer IO.

34BO outputs are taken out to the tiOR circuit 3B, and input to the AND circuit 37 via the inverter 39. When the steering signal is input to the solenoid coil 33A and ti33B, the output of the circuit 34A or 34B becomes a high level @11, and becomes a low level 10'' when the steering wheel is in the neutral position.

Then, both input signals of AND circuit 37 Hiro 1 become “1”.
", that is, only when the pulp stool 21 is switched to one side and the steering signal is not input to the solenoid 22., its output switches to the high level "@1719. 40, the solenoid valves 31 and 321 are energized and opened.

Therefore, the steering signal from the microcomputer 10 is applied to either one of the solenoids 22.
For example, when the input is made to 33 mm, the spool 21 moves to the left based on this, and pressure oil is sent to the four-wheel cylinder 3 to assist the steering wheel operation.

In this case, the pulp position sensor 35 detects the displacement of the Hiro spool 21 and outputs 111 to the AND circuit 37, but since the output of the circuit 34A is 11', the inverter 39 outputs 111 to the AND circuit 37. is 10 m, therefore, the AND circuit 37 remains at a low level output and the solenoid valves 31 and 32 are de-energized.

When the steering wheel is returned from such a steering condition and the steering signal is switched to a neutral signal, the stool 21 may have malfunctioned due to, for example, dirt in the oil, even though the solenoid 22 has been de-energized. Then, since the steering signal input to the OR circuit 38 is 0m, the inverter 39 inverts it, and thereby jj
) AND circuit 37 also outputs the pulp position center t35 @1
m, an excitation signal is output to the solenoid valves 31 and 32.

As a result, the solenoid valves 31, 32 open, and the spring chambers 26 and 27 at both ends of the spool 210 open, respectively, at the actuating port B.
and communicates with A.

When the stool 21 returns to the left position and raises the cineat, since the operating port B is still under high pressure, this pressure acts on the left sgelling chamber 26, turning the spool 21 back to the right. At this time.

The right spring chamber 27 communicates with the low pressure operating port A and does not interfere with the return action of the spool 21.

On the other hand, if the spool 21 is in the right position and fails to return, the operating port A that communicates with the right spring chamber 27 is under high pressure, so the stool 21 will be pushed back to the left. I can do it.

In this way, when the spool 21 remains displaced and the return shin failure occurs, the stool 21-
1- This hydraulic pressure is automatically eliminated when the spool 21 returns to the neutral position, so if the pulp position sensor 35 quickly detects the neutral return and the solenoid valve 31 is Even if the .32 opens and stays at 9,
Since the stool 21 is held in the neutral position, the stool 2
There will be no inconvenience such as 1 switching directly to the opposite side.

Furthermore, even if both TA valves 31 and 32 are opened at the same time, high pressure is always supplied only to the sgelling chamber that serves to return the stool 21, so there is no risk of malfunction.

In this embodiment, the line and solenoid 22 are provided with two coils 23A and 23B to have dual effect. However, solenoids are provided at both ends of the spool 210, and two pulp position sensors are also provided to increase the return cine. Good times stool 21
Of course, only the solenoid valve of the spring chamber on the side of pushing back 1c may be opened. Further, the control of the PS control pulp 9 is not necessarily performed by a microcomputer, but it is sufficient to include a control circuit that senses steering operation and outputs a signal.

As described above, according to the present invention, when the spool returns poorly, hydraulic pressure is applied to the end of the spool to forcibly return it to the neutral position, and the control pulp is cut off even though the handle is in the neutral position. It is possible to reliably prevent the risk of pressure oil being supplied to the arm cylinder while it is being pinched.

[Brief explanation of drawings]

FIG. 1 is a schematic configuration diagram of a conventional device, and FIG. 2 is a configuration diagram showing essential parts of the present invention. 2...Input shaft, 3...Rigwer cylinder, 9...P
S control pulp, 10... iikp computer. 11...Load sensor, 21...Spool, 22.
...Nrenoid, 23A, 23B...Coil, 26,
27,...Spring chamber, 29.30...Oil passage, 3
1.32... Solenoid valve, 35... Pulp position sensor,
37...AND circuit, 38...OR circuit. Patent Applicant Kayaba Kogyo Co., Ltd. 1': Agent Patent Attorney Masaru Goto Figure 1

Claims (1)

[Claims] A means for detecting the load and rotational direction of the input shaft connected to the steering wheel, a control circuit that outputs a steering signal based on the detected values, and a hydraulic actuator for the steering system that is switched by the signal from this control circuit. 7. In a power steering device comprising an electromagnetic control valve that selectively supplies pressure oil to There are passages at both ends of the spool that lead the pressure oil to the operating ports of the control pulp, and electromagnetic valves installed in the inner passages, and the pulp sol is not in the neutral position even though the steering signal is in the neutral position. sometimes ta
An arm power steering device characterized by comprising a control means for opening a valve and guiding pressure oil to the end of the spool to return it to a neutral position.