JPH0242713B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to power steering used in vehicles, and in particular to linkage type power steering.

This type of linkage power steering usually connects the nut via a drag ring.
Since it has been arranged between the link lever connected to the arm and the compensating rod connected to the steering wheel via the pittman arm and annual steering gear box, the connection between them is There is a tendency for movement delays to occur due to rattling or play in the parts or their steering gear boxes, and wear due to use increases this play, resulting in large movement delays. This changes the feeling of operating the steering wheel, and depending on the operating speed of the steering wheel, it becomes increasingly difficult to steer the actual steering arm at an appropriate speed. At times, the course tends to be disrupted by disturbances.

The purpose of this invention is to correct the increase in play in the steering wheel, prevent a delay in turning the steering wheel, that is, a delay in steering operation, reduce changes in the operating sensation, and automatically correct the disturbance in the course due to external disturbances. In this way, the static, dynamic, and transient characteristics of the steering,
The present invention also provides power steering for use in vehicles, which improves stability, reduces steering fatigue, and enables safer driving.

With these issues in mind, the power steering used in the vehicle of this invention includes an oil pump,
flow control valve, control
The control valve includes a valve and a power cylinder to be steered, the control valve forming a reaction chamber inside the control valve spool, and a sliding sleeve outside the control valve spool. They fit together so that they can slide back and forth, and the reaction force adjustment passage controls the
A pressure relief port of the valve is connected to the suction side of the oil pump, and a reaction force regulating valve is disposed in the reaction force passage to regulate the pressure in the reaction chamber of the control valve, and a pair of compensation A pressure chamber is defined from the pressure chamber on each side of the sliding sleeve, and a restriction is provided in a hydraulic supply passage communicating the control valve port of the flow control valve with the pressure port of the control valve. and a compensation pressure control passage is arranged to communicate the hydraulic supply passage upstream of the restriction with the compensation pressure chamber, and a compensation pressure control valve adjusts the pressure in the compensation pressure chamber. placed in the aisle, and the control
The unit is electrically connected to a steering amount sensor, a vehicle speed sensor, and a pressure sensor that senses the pressure in a pair of cylinder chambers of its power cylinder, and adjusts its reaction force adjustment valve and compensation pressure in response to signals from these sensors. The structure is such that the output current to the reaction force adjustment valve and the compensation pressure control valve is controlled so as to open and close the control valve.

Hereinafter, preferred specific examples of the power steering system used in a vehicle according to the present invention will be described with reference to the drawings.

The figure schematically shows an embodiment 10 of a power steering system used in a vehicle according to the invention, which is applied to a truck.

The power steering 10 is embodied in a linkage type for steering the front wheels, and includes a knuckle arm (not shown), a drag
link (not shown), link lever (not shown), steering wheel (not shown), manual steering gear box (not shown), pittman arm (not shown), compensating - Rod (not shown), oil pump 11, flow control valve 12,
A control valve 13, a power cylinder 14 disposed between its link lever and its compensating rod, a reaction force adjustment passage 15, a reaction force adjustment valve 16, and a pair of compensating pressure chambers 1.
7, 18, throttle 19, and compensation pressure control passage 2
0, 21, 22, a compensation pressure control valve 23, a control unit 24 for driving and controlling the reaction force adjustment valve 16 and compensation pressure control valve 23, and a steering amount electrically connected to the control unit 24. It is composed of a sensor 25, a vehicle speed sensor 26, a lateral acceleration sensor 27, and a pressure sensor 28.

The oil pump 11 is driven by an internal combustion engine (not shown) mounted on the truck, and is located in the hydraulic piping 30 in the hydraulic circuit of the power cylinder 14 and pumps into the oil reservoir 29. The internal combustion engine is configured to suck up oil and obtain a discharge amount of pressure oil that is approximately proportional to the rotational speed of the internal combustion engine.

Of course, the oil pump 11 is constructed similarly to the oil pump used in existing power steering systems, so a description of its construction will be omitted.

The flow control valve 12 is arranged in hydraulic lines 30, 31 in the hydraulic circuit of the power cylinder 14.

The flow control valve 12 has a pump port 32 connected to the discharge side of the oil pump 11, a control valve port 33 connected to the pressure port 45 side of the control valve 13, and a control valve port 33 connected to the pressure port 45 side of the control valve 13. pump 1
Suction port 3 connected to the suction side of 1
4 and an oil return control spool disposed so as to be able to slide back and forth within the casing, and adjusts the flow rate of the pressure oil sent to the pump port 32 side to a predetermined level. The flow rate is sent to the control valve port 33 side, and the surplus flow rate is returned from the suction port 34 to the suction side of the oil pump 11, that is, the oil reservoir 29 side.

Of course, the flow control valve 12
Since the structure is similar to a flow control valve used in existing power steering, a detailed explanation of its structure will be omitted.

The control valve 13 is constructed in the form of a spool and is incorporated into its power cylinder 14, which includes a compensating rod, a pitman arm, a manual steering gear
The valve is operated by the steering wheel via the box, and in the hydraulic circuit of the power cylinder 14, it is arranged in hydraulic piping 30, 31, the oil is discharged from the oil pump 11, and the flow rate is controlled by the flow control valve 12. It supplies the regulated pressure oil to the power cylinder 14 and returns the pressure oil worked in the power cylinder 14 to the suction side of the oil pump 11, that is, to the reservoir 29, and includes a valve body 35, It includes a control valve spool 36 with a reaction chamber 54 inside, a spool shaft 37, a pair of reaction plungers 38, 39, a pair of plunger stops 40, a reaction spring 41, and a slide sleeve 42. and within the valve body 35, the control
The reaction force chamber 5 is cooperated with the valve spool 36.
A pair of compensating pressure chambers 17, 18 are formed on both sides of the sliding sleeve 42, which are partitioned from each other.

The valve body 35 is incorporated into the cylinder body of the power cylinder 14 and has a spool bore 43 of a predetermined inner diameter and length.
is formed inside the spool bore 4.
3 concentrically, i.e., with a sleeve bore 44 having an inner diameter larger than the inner diameter of its spool bore 43 and a length shorter than the length of its spool bore 43, as shown. is forming.

In addition, the valve body 35 has its sleeve
A pressure port 45 opened to the bore 44, a pair of cylinder ports 46, 47, a pair of tank ports 48, 49, a reaction force port 50, and a pair of compensation pressure ports 51, 52 are provided, and the flow
The pressure oil whose flow rate is adjusted by the control valve 12 is transferred to the cylinder chamber 77 of the power cylinder 14,
78, its pressure port 45 is connected to the supply side of its hydraulic line 30, and its cylinder ports 46, 47 are connected to its hydraulic lines 30, 31.
In addition, its tank port 4 is connected to the cylinder side of
8 and 49 are connected to the hydraulic piping 31, respectively.

The control valve spool 36 forms a reaction chamber bore 53 that is open at both ends so as to form a reaction chamber 54 inside, and is disposed in the spool bore 43 so as to be able to reciprocate and slide.

Also, the control valve spool 3
6 is a large diameter plunger at one end of the reaction force chamber bore 53.
A small-diameter plunger bore 56 is formed at the other end of the bore 55 and the reaction force chamber bore 53, a pressure communication port 57 is formed to connect the reaction force chamber 54 to the pressure port 45, and a pressure communication port 57 is formed at the other end of the reaction force chamber bore 53. It is provided with a reaction force release port 58 that communicates with the reaction force chamber 54.

Furthermore, the control valve spool 36 is provided with ring grooves 59, 60 forming a spool oil chamber for switchingly connecting the pressure port 45 to the cylinder ports 46, 47.

The spool shaft 37 has one end passed through the control valve spool 36;
Moreover, the spool 36 is configured such that the spool 36 is slid back and forth within the spool bore 43.
A pair of spool stoppers 61 are provided at both ends of the spool 36 to fix the spool 36, and the other end is connected to an empensating rod.

Furthermore, to explain the fixing structure of the spool 36 in detail, the spool shaft 37 has a sleeve-shaped spacer fitted to one end side of the spool shaft 37 so as to be positioned between the spool stoppers 61. 62 and a nut 63 threaded to one end of the spool shaft 37.
Spool stopper 61 fixed to one end side of 7
The spool 36 is sandwiched between them and the spool 36 is fixed.

The spool stoppers 61 are formed in a plate shape, and have two small holes 64 opened in the stopper surface at predetermined positions and spaced apart from each other by a predetermined distance.

The reaction force plungers 38 and 39 are of large diameter,
The large-diameter reaction plunger 38 is reciprocally slidably fitted into the large-diameter plunger bore 55 and the spacer 62 on the spool shaft 37, and the small-diameter reaction plunger 39 is formed with a small diameter. It is reciprocally slidably fitted into the small diameter plunger bore 56 and a spacer 62 on the spool shaft 37 to close a reaction chamber 54 formed within the control valve spool 36 thereof.

In this way, the reaction force plungers 38 and 39 are designed to have a large diameter and a small diameter.
In this power steering 10, when the power cylinder 14 retracts, the driver feels that the steering is heavy, and when the power cylinder extends, the driver feels that the steering is soft. In other words, since there is a difference in the left and right steering forces, it is necessary to equalize the steering forces for right and left turns.

A pair of plunger stoppers 40 each have two plunger stops protruding from both inner end surfaces of the spool bore 43.
The pins pass through the small hole 64 of the spool stopper 61, abut their tips on the corresponding large-diameter and small-diameter reaction force plungers 38, 39, and extend toward the inner end surface of the spool bore 43. The movement of the reaction force plungers 38, 39 is regulated, and as the spool shaft 37 moves, the reaction force spring 41 cooperates to give a pumping action to the reaction force plungers 38, 39. The oil filled in the force chamber 54 is compressed to change the reaction force felt on the spool shaft 37.

The reaction spring 41 is disposed between the reaction plungers 38, 39 and around the spool shaft 37, ie, the spacer 62, to impart a pumping action to the reaction plungers 38, 39, and to provide a pumping action to the reaction plungers 38, 39. In other words, it functions as a centering spring.

The slide sleeve 42 has a pressure port 45 on its valve body 35, a pair of cylinder ports 46, 47, and a pair of tank ports 48, 4.
9, and reaction port 50 and its pressure communication port 57 of control valve spool 36.
and a pressure intermediate communication port 65 associated with the reaction force relief port 58, a pair of intermediate cylinder ports 6
6, 67, a pair of intermediate tank ports 68, 69
and a reaction intermediate relief port 70 that fits around the control valve spool 36 and is guided by the control valve spool 36 and slid reciprocatingly within the sleeve bore 44 of the control valve spool 36 . A pair of compensating pressure chambers 17, 18 defined from the force chamber 54 are formed on opposite sides of the sleeve bore 44.

Of course, the sliding sleeve 42 is enabled to return to its neutral position in the sleeve bore 44 by means of centering springs 71, 72 arranged in the compensating pressure chambers 17, 18, respectively.

Therefore, with the slide sleeve 42 configured in this manner, even when the control valve spool 36 is slid to either side while the slide sleeve 42 is held in the neutral position, the control valve spool 36 is also held in the neutral position.・Even when the valve spool 36 is held in the neutral position and is slid to either side, the pressure port 45 and tank ports 48, 49 are connected to the cylinder ports 46, 47 in the same way. Switched and connected.

The power cylinder 14 includes a cylinder body 73 pivotally connected to a link lever, and a pair of cylinder chambers 77 and 78 formed within a cylinder bore 76 of the cylinder body 73.
It consists of a power piston 74 disposed in the cylinder bore 76 so as to be able to slide back and forth, and an operating rod 75 whose one end is fixed to the power piston 74 and the other end is pivotally connected to the chassis side. 80 is connected to the hydraulic pipes 30 and 31, and is driven by pressure oil controlled by the control valve 13.

The reaction force adjustment passage 15 is made up of piping that connects a reaction force port 50 formed in the valve body 35 of the control valve 13 to the hydraulic piping 31, and a reaction force relief port 58 is connected to the reaction force intermediate relief port 7.
0 to the reaction port 50, the pressure oil in the reaction chamber 54 is transferred to the oil pump 1.
1, i.e. the oil reservoir 29
The amount of oil released is also controlled by the reaction force adjustment valve 16.

The reaction force regulating valve 16 includes a valve body 81 having a spool chamber (not shown) and a pair of ports 82, 83 in communication with the spool chamber, and reciprocally slides within the spool chamber. It includes a spool (not shown) disposed such that it can change the passage cross-sectional area within its spool chamber in response to its reciprocating sliding movement, and an electric servo motor 84 for driving the spool. Depending on the speed, the spool is slid back and forth within the spool chamber to change the passage cross-sectional area within the spool chamber and adjust the flow rate of pressure oil flowing between the ports 82 and 83;
It is configured to change the reaction force generated by the pressure oil in the reaction force chamber 54 of the control valve 13.

Furthermore, to be more specific, in this reaction force adjustment valve 16, when the truck is traveling at low speed,
Of course, the servo motor 84 drives the spool so as to widen the cross-sectional area of the passage and, when the truck travels at high speed, narrow the cross-sectional area of the passage. 25, is driven and controlled by a control unit 24 based on signals from a vehicle speed sensor 26, a lateral acceleration sensor 27, and a pressure sensor 28.

A pair of compensating pressure chambers 17, 18 are fitted around the control valve spool 36 of the control valve 13, as previously described.
At both ends of the sliding sleeve 42 guided by the control valve spool 3
6 and is formed in the sleeve bore 44 to cause the power cylinder 14 to follow the steering direction, steering speed, amount of steering, etc. of the steering wheel, thereby avoiding delays in the operation of the power cylinder 14. Thus, the supplied pressure oil drives the slide sleeve 42 and compensates for the operation of the control valve 13.

Restriction 19 is a fixed restriction that connects control valve port 33 of flow control valve 12 and pressure port 4 of control valve 13.
5, compensation pressure control passages 20, 21, 22 arranged in the hydraulic piping 30 and described in detail later.
It is possible to introduce relatively high pressure oil into the compensating pressure chambers 17 and 18 via the compensating pressure chambers 17 and 18.

The compensation pressure control passages 20, 21, 22 are composed of piping, and the hydraulic piping 3 on the upstream side of the throttle 19
0 to the compensation pressure chambers 17 and 18, respectively, and a part of the pressure oil flowing through the hydraulic pipe 30 on the upstream side of the throttle 19 is supplied to the compensation pressure chambers 17 and 18. is controlled by a compensation pressure control valve 23, which will be described in detail later.

Therefore, the compensation pressure control passage 20 has one end connected to the hydraulic pipe 30 on the upstream side of the throttle 19 and the other end connected to the pressure port 89 of the compensation pressure control valve 23.
1 and 22 are control ports 9 of the compensation pressure control valve 23
0 and 91 and the compensation pressure ports 51 and 52 of the control valve 13 are connected.

The compensation pressure control valve 23 is a spool-type directional control valve, and includes a valve body 85, a spool 87 that reciprocates within a spool chamber 86 formed in the valve body 85, and a spool 87 that slides back and forth within a spool chamber 86 formed in the valve body 85.
an electric servo motor 88 for driving 7;
The spool 87 is driven by the servo motor 88 to connect the pressure port 89 to the control port 9.
Switching between 0,91 and its compensation pressure chamber 17,1
Change the pressure of 8 and its control valve 13
drive the slide sleeve 42 of. Of course,
The servo motor 88 is driven by control current from the control unit 24, which will be discussed in more detail below.

The control unit 24 includes a steering amount sensor 25, a vehicle speed sensor 26, and a lateral acceleration sensor 2.
7 and the pressure sensor 28, respectively, and electric servo motors 84, 88 of the reaction force regulating valve 16 and the compensation pressure control valve 23.
The output sides are electrically connected to the sensors 25, 26, 27, and 28, and according to the signals from the sensors 25, 26, 27, and 28,
output signals to those servo motors 84, 88;
In other words, it controls the output current, and mainly controls input and output circuits, memory circuits, arithmetic circuits,
It consists of a control circuit and a power supply circuit.

The control unit 24 also stores a predetermined steering pattern, inputs signals from the sensors 25, 26, 27, and 28, and
Based on the steering pattern, output signals are sent to the servo motors 84, 88, and signals from the sensors 25, 26, 27, 28 are input once, so that, for example, play occurs in the steering wheel. If so, the play is given as an electric signal by the steering amount sensor 25, so the play is memorized, and the next steering operation is predicted and compensated for by taking the play into account. An output signal is sent to the electric servo motor 88 of the pressure control valve 23 to reduce its play.

The steering amount sensor 25 detects the rotation direction, rotation speed, and rotation angle of the steering wheel, that is, the steering shaft, and is arranged on the steering shaft at a predetermined position.

The vehicle speed sensor 26 detects the traveling speed of the truck and is disposed on the output shaft of a transmission mounted on the truck.

The lateral acceleration sensor 27 detects the acceleration of the truck in the lateral direction when the truck is running and converts the acceleration into an electrical signal, and is disposed on the body of the truck.

The pressure sensor 28 is connected between the hydraulic pipes 30 and 31 on the cylinder side, and is connected to the power cylinder 1.
The pressure difference between the four cylinder chambers 77 and 78 is sensed and the pressure difference is converted into an electrical signal.

The above-mentioned steering amount sensor 25, vehicle speed sensor 26, lateral acceleration sensor 27, and pressure sensor 28
are, of course, electrically connected to the input circuits of the control unit 24, respectively, and the output circuits of the control unit 24 are connected to the electric servo motors 84, 84 of the reaction force regulating valve 16 and the compensation pressure control valve 23, respectively. 88, respectively.

Therefore, the reaction force adjustment valve 16 and the compensation pressure control valve 23 are connected to the steering amount sensor 25, the vehicle speed sensor 26, the lateral acceleration sensor 27, and the pressure sensor 2.
It is opened and closed by its control unit 24 in response to signals from 8.

Next, to describe the running of the truck using the power steering 10 described above, that is, the steering of the front wheels of the truck when the truck is running, the control unit 24 controls the steering amount sensor 25, the vehicle speed sensor 26, the lateral Acceleration sensor 2
7 and the pressure sensor 28, respectively, and provide output signals to the electric servo motors 84, 88 of the reaction force regulating valve 16 and the compensation pressure control valve 23, and are ready to adapt to steering wheel operation. .

If there is play in the steering wheel now, the control unit 24 will
Based on the input signals from the steering amount sensor 25 and the pressure sensor 28, an output signal to the electric servo motor 88 of the compensation pressure control valve 23 is calculated, that is,
The output current is changed to drive the compensation pressure control valve 23 to avoid the increase in play.

More specifically, if the spline joint of the steering shaft is rattling and there is significant play in the steering wheel, if the steering wheel is rotated, the control unit 24 will ,
The output signal detected by the steering amount sensor 25 and the pressure sensor 28 is inputted from the steering amount sensor 25 and the pressure sensor 28, and the determined output signal is calculated based on the signal. to servo motor 88.

As such, the output signal, i.e. the output current, is transferred from the control unit 24 to the electrical servo.
Once flowing to the motor 88, its compensating pressure control valve 23
, the spool 87 is slid by its electric servo motor 88 so that the hydraulic line 3
Pressure oil on the upstream side of the throttle 19 flowing through the throttle 19 is supplied to either one of the compensation pressure chambers 17 and 18. Of course, the selection of either one of the compensation pressure chambers 17, 18 and the amount of pressure oil are determined according to the signal from the steering amount sensor 25, that is, the rotation speed, rotation direction, and rotation angle of the steering shaft. be done.

For example, when the steering wheel is rotated clockwise, the control unit 2
4 inputs the signal from the steering amount sensor 25,
Further, by sending an output signal to the electric servo motor 88, the spool 87 of the compensating pressure control valve 23 is slid to the left in the figure.

If the spool 87 is so slid, the pressure port 89 of the compensating pressure control valve 23 is connected to the control port 91 and the oil pump 11
Pressure oil sent from the flow control valve 12 to the upstream side of the restriction 19 is supplied to the compensation pressure chamber 18 via compensation pressure control passages 20 and 22.

When the compensation pressure chamber 18 is supplied with pressure oil, the slide sleeve 42 is slid to the right in the figure, so that if the slide sleeve 42 is moved, the pressure port and the pressure intermediate communication port 45, 65 is connected to the cylinder port 46 via the ring groove 59, and the pressure oil supplied from the oil pump 11 via the flow control valve 12 flows into the cylinder chamber 77 on the right side of the power cylinder 14, and the power - The piston 74 is slid to the left in the figure, and its power cylinder 14 is extended.

Therefore, in this power steering system 10, the steering shaft, the manual gear box, which transmits the steering of the steering wheel to the control valve spool 36 of the control valve 13,
In the mechanism including the pittman arm and compensating rod, for example, as mentioned above, if there is play in the spline joint of the spline shaft and there is large play in the steering wheel, the steering - If the wheel is rotated, even within the range of its play, its power cylinder 14
avoids steering wheel lag,
It operates properly and steers the front wheels to avoid so-called operation delays.

Of course, to enable such operation, the control unit 24 inputs signals from the steering amount sensor 25 and pressure sensor 28 and outputs them to the electric servo motor 88 of the compensating pressure control valve 23. Send signal and compensate pressure control valve 2
3 to maintain a predetermined relationship between the steering amount of the steering wheel and the pressure inside the power steering wheel 14, thereby avoiding an increase in play in the steering wheel.

Furthermore, this control unit 24
Once the play is memorized, the next steering play is predicted by taking that play into account, and the output current to the compensation pressure control valve 23 is changed, and such an operation is repeated to prevent the increase in the play. Works to prevent it in advance.

Also, if the steering wheel is rotated in the opposite direction to that described above, a substantially reverse operation is performed and the sliding sleeve 42
is slid to the left in the figure, and accordingly, its power cylinder 14 performs a retracting movement in which the power piston 74 is slid to the right in the figure, and the front wheel is moved in the opposite direction to that described above. to steer.

Next, when the steering wheel is operated, if there is a delay in turning the front wheels, the control unit 24 inputs the operating speed of the steering wheel detected by the steering amount sensor 25, and A comparison calculation is made with the stored steering pattern, and an output current as an output signal is sent to the electric servo motor 88 of the compensation pressure control valve 23.

That is, as in the case of play described above, pressure oil is supplied from the upstream side of the restriction 19 of the hydraulic piping 30 to either one of the compensation pressure chambers 17 and 18 by the compensation pressure control valve 23, and the slide sleeve 42 is slid to either the left or right in the figure, and as the slide sleeve 42 moves, the power
Cylinder 14 is driven.

At that time, the control unit 24
The degree of the steering delay is memorized, and the steering delay is predicted based on the steering delay, and based on the input signal detected by the steering amount sensor 25, the steering delay is predicted so that the steering delay is reduced. The comparatively calculated output signal is sent to the electric servo motor 88 to switch and operate the compensation pressure control valve 23.

As a result, a delay in turning the front wheels relative to the operation of the steering wheel is prevented, and a change in the operating feel of the steering wheel due to the delay in turning is prevented.

Next, when the truck is running, if a disturbance, that is, a large external force in the direction of overturning the truck, acts on the truck and lateral acceleration is generated, then the disturbance, that is, the lateral external force causes the truck to overturn. , the front wheels are steered, resulting in a pressure difference between the cylinder chambers 77, 78 of the power cylinder 14.

In other words, a large lateral acceleration occurs when the steering wheel is not operated,
Further, when a pressure difference occurs between the cylinder chambers 77 and 78, the control unit 24 performs a comparison calculation based on the signals from the steering amount sensor 25, lateral acceleration sensor 27, and pressure sensor 28, and outputs the result as an output signal. output current to the electric servo motor 88 of the compensating pressure control valve 23.

As output current flows through the electric servo motor 88, the spool 87 slides in the compensating pressure control valve 23, causing pressure oil to flow into the hydraulic line 3.
0 from the upstream side of the throttle 19, its compensation pressure chamber 17,
18, its slide sleeve 42 is slid in substantially the same manner as in the previous case,
The power cylinder 14 is activated to correct the steering of the front wheels due to the disturbance.

Next, to describe the reaction force during steering in the power steering 10 in relation to the running condition of the truck, the flow rate of pressurized oil from the oil pump 11 is adjusted by the flow control valve 12, and the flow rate is adjusted to a predetermined level. The flow rate is sent to pressure port 45 of control valve 13.

If the control valve spool 36 is in the neutral position as shown in the figure, the pressure oil sent to the pressure port 45 will primarily flow through the hydraulic piping 31 to the tank ports 48, 4.
9 and returned to the oil reservoir 29, but when the steering wheel is steered, its spool shaft 37 is pushed or pulled in either direction via the manual steering box, pitman arm, and compensating rod. and if the control valve spool 36 is slid in the direction of the movement of the spool shaft 37, the pressure oil will flow into the hydraulic line 3 in response to the movement of the control valve spool 36.
Power cylinder 1 via the cylinder side of 0 and 31
It is supplied to either one of the four cylinder chambers 77, 78 and the reaction force chamber 54.

The reaction force against the steering is provided by the pressure in the reaction force chamber 54 adjusted by the reaction force adjustment valve 16 and the reaction force spring 41.

In such operation of the power steering 10, if the truck is driven at low speed,
The control unit 24 is the vehicle speed sensor 2
6 and the output signal, that is, the output current, which is compared and calculated based on the input signal, is sent to the electric servo motor 84 of the reaction force adjustment valve 16. is slid and the passage within the spool chamber is opened relatively wide.

Therefore, the pressure oil in the reaction force chamber 54 flows to the reaction force relief port 58, the reaction force intermediate relief port 70, and the reaction force port 50, and further passes through the reaction force adjustment passage 15 and the hydraulic piping 31 to the oil reservoir. 29, the pressure oil in the reaction chamber 54 does not provide a large resistance to the sliding of the reaction plunger 38 or 39, and steering during low speed running is performed with a small operating force.

Of course, if the truck is steered when stopped, the traveling speed is zero and the passage of the reaction force regulating valve 16 is opened to the maximum, so the pressure in the reaction force chamber 54 is close to atmospheric pressure. In this state, cutting, shifting, recutting, etc. can be performed with a small amount of operating force.

If the truck is traveling at high speed, the control unit 24 inputs a signal from the vehicle speed sensor 26, and adjusts the reaction force by adjusting the output signal, that is, the output current, which is compared and calculated based on the input signal. Electric servo motor 84 of valve 16
Therefore, the spool is slid in the reaction force regulating valve 16, and the passage in the spool chamber is opened narrowly.

Therefore, the pressure oil in the reaction force chamber 54 is more difficult to return to the oil reservoir 29 due to the throttling effect of the reaction force adjustment valve 16, so that the pressure oil in the reaction force chamber 54 is Reaction force plunger 38 or 3
This results in a large resistance to the sliding movement of the wheel 9, and as a result, steering at high speeds is performed with a relatively large operating force. In this way, a relatively large operating force is required for steering during high-speed running, and running stability is improved.

The power steering 10 is operated as described above when the truck is running at low speed, at high speed, or when the truck is stationary. Therefore, in the power steering 10, when the power cylinder 14 performs a retraction operation and an extension operation, the difference between the right turning operation force and the left turning operation force becomes extremely small. The turning and left turning steering forces are equalized. As a result, this power steering 1
0 relieves the driver from physical fatigue caused by truck steering.

According to the above-mentioned invention, the increase in play in the steering is corrected, steering delay, that is, delay in steering operation is prevented, and changes in the operating feeling due to the steering delay are reduced, and the course change due to disturbances is reduced. The disturbances are automatically corrected, thus improving the static, dynamic, transient and stability characteristics of the steering, reducing steering fatigue and allowing safer driving, inter alia: When the power cylinder retracts and extends, the difference between the right-hand and left-hand turning forces becomes extremely small, in other words, the right-hand and left-hand steering forces are more equalized; , steering becomes more stable, and the driver is relieved from physical fatigue caused by steering.

As mentioned above, from the specific examples of the present invention explained with reference to the drawings, it is difficult for those who have ordinary knowledge in the technical field to which the invention pertains to understand the following:
Various design modifications and changes can be easily made, and furthermore, it is possible that the content of this invention satisfies essentially the same problems and achieves the same effects as that invention. It could easily be replaced by embodiments that are essentially the same as the invention.

[Brief explanation of drawings]

The figure is a schematic view showing a specific example of the power steering system of the present invention, which is embodied as a linkage type and is applied to a truck. 10...Power steering, 11...Oil/
pump, 12...flow control valve,
13... Control valve, 14... Power cylinder, 15... Reaction force adjustment passage, 16... Reaction force adjustment valve, 17, 18... Compensation pressure chamber, 19... Throttle, 2
0, 21, 22...Compensation pressure control passage, 23...Compensation pressure control valve, 24...Control unit, 2
5... Steering amount sensor, 26... Vehicle speed sensor, 27... Lateral acceleration sensor, 28... Pressure sensor.

Claims (1)

[Claims] 1. In a steering device including an oil pump, a flow control valve, a control valve, and a power cylinder, the control valve has a reaction chamber inside the control valve spool. form, and
A slide sleeve is reciprocally slidably fitted on the outside of the control valve spool, and a reaction force adjustment passage connects the pressure relief port of the control valve to the suction side of the oil pump, and the reaction force adjustment valve is connected to the suction side of the oil pump. is disposed in the reaction force adjustment passage to adjust the pressure in the reaction force chamber of the control valve, a pair of compensating pressure chambers are separated from the pressure chamber and formed on opposite sides of the slide sleeve; The restriction connects the control valve port of the flow control valve to its control valve port.
disposed in the hydraulic supply passage communicating with the pressure port of the valve, a compensation pressure control passage communicating the hydraulic supply passage upstream of the restriction with the compensation pressure chamber; and a compensation pressure control valve communicating the hydraulic supply passage upstream of the restriction with the compensation pressure chamber. and a control unit electrically connects a steering amount sensor, a vehicle speed sensor, and a pressure sensor that senses the pressure in a pair of cylinder chambers of the power cylinder to adjust the pressure. The output current to the reaction force adjustment valve and the compensation pressure control valve is controlled so that the reaction force adjustment valve and the compensation pressure control valve are connected to each other, and the reaction force adjustment valve and the compensation pressure control valve are opened and closed according to the signals from those sensors. Power steering used in vehicles.