JPS62131872A - Control valve used in speed sensitive type power steering and speed sensitive type power steering - Google Patents

Abstract

PURPOSE:To reduce the consumption of power, by providing a pair of reaction pistons which are driven in accordance with the motion of a spool shaft, and by limiting the pistons with the use of a pair of stoppers. CONSTITUTION:Reaction pistons 40, 41 are fitted slidably in piston bores 54, 55 and onto a spool shaft 39, and are limited in their movements toward the ends of the bores by means of stoppers 42, 43. When a hollow spool 38 slides in the direction of movement of the spool shaft 39, hydraulic pressure is fed into one of chambers 26, 27 in a power cylinder 11 through communication passages 31, 32. Simultaneously, a control unit 20 receives a signal from a vehicle speed sensor 20, and controls actuators 65, 66 for variable restrictors 18, 19. Thereby, the flow rate of required hydraulic oil is decreased, and therefore, it is possible to reduce the consumption of power for driving an oil pump 12.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a control valve used in speed-sensitive power steering for a vehicle and a speed-sensitive power steering incorporating the control valve.

Background Art This type of power steering attempts to optimize the steering force by changing the hydraulic reaction force according to the vehicle speed.In other words, at low speeds, the hydraulic reaction force is lowered to lighten the steering force.
Also, at high speeds, the hydraulic reaction force is high, increasing the steering force, and at low speeds, a large amount of pressure oil leaks from the control valve into the oil reservoir, thus increasing the hydraulic reaction force. The pressure oil that flows into the control valve to change the flow rate was wasted.

Objectives and Problems of the Invention The objects and problems of this invention are to reduce the required flow rate of pressure oil that changes hydraulic reaction force according to vehicle speed, to optimize steering force, and to reduce power consumption. Our objective is to provide control valves used in sensitive power steering.

The purpose and problem of this invention is also to reduce the required flow rate of pressure oil flowing into the control valve, change the hydraulic reaction force according to the vehicle speed, optimize the steering force, and reduce power consumption. type power steering.

Summary of the structural invention related to the object/problem: Contents of the claimed invention In relation to the above-mentioned object/problem, the control valve used in the speed-sensitive power steering of this invention has a valve bore, and a valve body having a pump port, a pair of power cylinder ports, a pair of tank ports, a reaction pressure supply port, and a reaction pressure relief port opening into the valve bore in position; and the valve.・A reaction chamber that is arranged to be able to reciprocate and slide in the valve bore of the body and is formed inside, a pair of piston bores that are formed at both ends of the reaction chamber, and the reaction pressure is applied to the reaction chamber. A hollow spool having a reaction pressure supply side communication port that communicates the supply port and a reaction pressure relief side communication port that communicates the reaction pressure relief port with the reaction chamber;・Slide back and forth inside the bore,
a spool shaft having a pair of spool stops disposed at opposite ends of the spool to fixedly connect the spool; ,
A pair of reaction pistons that are reciprocally slidably fitted into a pair of piston bores and a spool shaft, and a pair of reaction piston stoppers that restrict movement of the reaction pistons toward the end of the valve bore. A reaction spring disposed between the reaction piston,
The reaction pressure supply port can be connected to the oil pump discharge side, and the reaction pressure relief port can be connected to the oil reservoir, and depending on the vehicle speed, the reaction pressure supply port and the reaction pressure supply side communication port can be connected. In addition to being able to control the flow rate of pressurized oil from the oil pump to the reaction chamber, and from the reaction chamber to the oil reservoir via the reaction pressure relief communication port and the reaction pressure relief port. The vehicle speed sensitive power steering system of this invention makes it possible to stop the flow of the pressure oil and reduce the required flow rate of the pressure oil that changes the hydraulic reaction force according to the vehicle speed. In a steering device configured with a hydraulic circuit including a power cylinder with a chamber, an oil pump, a control valve, and an oil reservoir, the control valve has a valve bore and a predetermined position. In the valve bore, the pump is opened.
a valve body having a port, a pair of power cylinder ports, a pair of tank ports, a reaction pressure supply port, and a reaction pressure relief port; and a reaction chamber formed inside, a pair of piston bores formed at both ends of the reaction chamber, a reaction pressure supply side communication port that communicates the reaction pressure supply port with the reaction chamber, and the reaction chamber. - A hollow spool with a reaction pressure relief side communication port that communicates the reaction pressure relief port with the chamber, and a hollow spool at both ends of the spool so as to penetrate the hollow spool and reciprocate the spool into the valve bore. a spool shaft having a pair of spool stops disposed and fixedly connecting the spool; and a piston bore of the pair, the piston bore being driven by the spool stop in response to movement of the spool shaft. and a pair of reaction pistons fitted to the spool shaft so as to be able to reciprocate and slide, a pair of reaction piston stoppers that restrict the movement of the reaction pistons toward the bore end of the valve bore, and It consists of a reaction spring placed between the pistons and connects the oil pump and oil reservoir to the cylinder chamber of the power cylinder. Disposed in the piping of the hydraulic circuit, a reaction pressure supply passage connects the reaction pressure supply port to the discharge side of the oil pump, and a reaction pressure relief passage connects the reaction pressure relief port to the oil reservoir side. , a reaction pressure supply side variable throttle is disposed in the reaction pressure supply passage, a reaction pressure relief side variable throttle is disposed in the reaction pressure relief passage, and the control unit controls the variable pressure in response to a signal from the vehicle speed sensor. It is configured to open and close the aperture,
Opens and closes the variable throttle according to the vehicle speed, controls the flow rate of the pressure oil flowing to the control valve for the hydraulic reaction force, and reduces the required flow rate of the pressure oil that changes the hydraulic reaction force according to the vehicle speed. It makes it possible to optimize the steering force, reduce the power consumed by the oil pump, and close the variable throttle on the reaction relief side, especially when the vehicle is running at low speeds, and at the same time,
The variable throttle on the reaction pressure supply side is opened to reduce the required flow rate of pressure oil that provides hydraulic reaction force, lighten the steering force, and in this way eliminate waste in the flow rate of pressure oil.

DESCRIPTION OF SPECIFIC EXAMPLES Hereinafter, preferred specific examples of the control valve used in the speed-sensitive power steering system and the speed-sensitive power steering system according to the present invention will be described with reference to the drawings.

The figure shows a specific example 14 of a control valve used in the speed-sensitive power steering of the present invention applied to a truck, and a specific example 10 of the speed-sensitive power steering. It is used by being incorporated into the speed-sensitive power steering 10.

The speed-sensitive power steering system 1o is capable of steering a pair of front wheel axles (not shown) that are swingably connected to both ends of the front axle (not shown) of the truck. Cylinder 11, oil pump 12, flow control valve 13, control valve 1
4, Oil reservoir 15, Steering wheel (
(not shown), a steering shaft (not shown), a pitman arm (not shown), a drag link (not shown), and a knuckle arm (not shown), and its power The cylinder 11 , the oil pump 12 , the flow control valve 13 , the control valve 14 and the oil reservoir 15 are connected to the hydraulic circuit by supply and return hydraulic lines 21 , 22 , and also by a reaction pressure supply channel 16 . , reaction pressure relief passage 17, reaction pressure supply side variable throttle 18
, a reaction pressure relief side variable throttle 19, and a control unit 20.

The power cylinder 11 is configured as an integral type including a steering gear box that operates the control valve 14 and enables manual steering, and is attached to the chassis frame (not shown) of the truck. It was swingably connected to both ends of a front axle located at the front via a knuckle (not shown) and a king pin (not shown), and rotatably supported a front wheel (not shown). It is connected to the front wheel axle via a pitman arm, drag link, and knuckle arm. Of course, the front wheel axles are connected to each other by a tie rod (not shown) and a pair of tie rod arms (not shown).

The power cylinder 11 incorporates the valve body 37 of the control valve 14 and the power cylinder port 47.4 of the control valve 14.
The power cylinder body 23 has a cylinder bore 24 that communicates with an oil port 29. A power piston 25 forming a pair of connected cylinder chambers 26, 27 in its cylinder bore 24 corresponding to . and a sector shaft 26 that transmits motion to its pitman arm.

Moreover, this power cylinder 11 has its cylinder chamber 2
6 oil port 29 and its control valve 1
A communication passage 31 communicates with the power cylinder port 47 of the control valve 14, and a communication passage 32 communicates the oil port 30 of the cylinder chamber 27 with the power cylinder port 48 of the control valve 14. Of course,
The communication passage 31, 32 connects the control valve 1
4 to the supply hydraulic piping 21 and the return hydraulic piping 22, and the power cylinder 1
1, the oil pump 12, the flow control pulp 13, the control pulp 14, and the oil reservoir 15 are part of the supply and return hydraulic piping 21-22 connecting them to the hydraulic circuit.

With a power cylinder 11 so configured, the force and movement of its power piston 11 is transmitted to the front wheel via its sector shaft 28, pitman arm, drag link and knuckle arm, and thus The power cylinder 11 then steers the front wheels.

The oil pump 12 is driven by a diesel engine (not shown) mounted on the truck,
In order to supply pressure oil to the power cylinder 11, the oil・The oil in the reservoir 15 is sucked up and pressurized, and the diesel
The amount of pressure oil discharged is approximately proportional to the engine speed. Of course, the oil pump 12 is
Since it is manufactured to have a similar structure to the oil pump used in existing power steering systems, we will omit its explanation.

The flow control pulp 13 is located in the hydraulic circuit in a supply hydraulic line 21 connecting the control pulp 14 to the oil pump 12 and oil reservoir 15, and
It is connected to the return hydraulic line 22 by a pulp bypass 36 .

The flow control pulp 13 is connected to a pump port 33 connected to the discharge side of the oil pump 12.
, the pump port 46 of its control pulp 14
a control pulp port 34 connected to the oil pump 12 and a return port 35 connected to the suction side of the oil pump 12; The control spool (not shown) adjusts the flow rate of pressure oil sent to the pump boat 33 side, and sends a predetermined flow rate to the control pulp port 34 side. In addition, the excess flow rate of pressure oil is
Port 35 returns the oil to the oil reservoir 15 via the control pulp 36.

Of course 88, the flow control pulp 13 is
It has a structure similar to that of flow control pulp used in existing power steering systems, so a detailed explanation of its structure will be omitted.

The control pulp 14 is configured as a hydraulic reaction type spool pulp, and is incorporated into the power cylinder body 23 of the power cylinder 11, and is connected to an input shaft (not shown) connected to the steering shaft. ), the spool shaft 39 is coupled to the spool shaft 39, the pulp is operated by the steering wheel, and in the hydraulic circuit, the supply hydraulic pressure connects the oil pump 12 and the oil reservoir 15 to the power cylinder 11. Piping 21, return side hydraulic piping 22, and communication path 31
．． 32, it controls the direction of the pressure oil discharged from the oil pump 12 and supplies it to the power cylinder 11, and also controls the direction of the pressure oil worked in the power cylinder 11, and supplies the oil to the power cylinder 11. The pressure oil is returned to its oil reservoir 15 on the suction side of the pump 12.

The control pulp 14 is connected to the valve body 37
, a hollow spool 38, a spool shaft 39,
It is manufactured to have a structure including a pair of reaccitan pistons 40, 41, a pair of reaccitan piston stops 42, 43, and a reaccitan spring 44.

The valve body 37 is formed with a pulp pore 45 and is connected to the power cylinder 11 of the power cylinder 11.
A pump port 4 is incorporated into the body 23 and opens into a valve bore 45 thereof at a predetermined position.
6, a pair of power cylinder ports 47, 48, a pair of tank ports 49, 50, a rear axitan pressure supply port 51, and a rear axidin pressure relief port 52.

These pump ports 46, power cylinder ports 47, 48, tank ports 49, 50, reaction pressure supply port 51 and reaction pressure relief port 52.
The openings on the inner peripheral surface of the valve bore 45 are respectively formed into ring grooves.

In addition, this control valve 14 is
In order to supply the pressure oil whose flow is regulated by the control valve 13 to the cylinder chambers 26 and 27 of the power cylinder 11, the pump port 46 is connected to the flow control valve in the supply hydraulic piping 21. 13 control valve port 34, its power cylinder port 47.48 with its communication passage 31.32,
Its power cylinder 11 oil port 29.30
and its tank ports 49, 50 are each connected to its oil reservoir 15 by a return hydraulic line 22, and its reaction pressure supply port 51 is connected to its oil reservoir 15 by a return hydraulic line 22, and its reaction pressure supply port 51 is The pressure supply piping 16 is connected to the supply hydraulic piping 21, and the reaction pressure relief port 52 is connected to the return hydraulic piping 22 through the reaction pressure relief piping 17.

The hollow spool 38 is reciprocally slidably disposed in a valve bore 45 formed in the valve body 37;
A reaction chamber 53 is formed inside.

Also, that hollow Subu! The L/38 has piston bores 54 and 55 formed at each end of its reaction chamber 53, and a pump port 46 and a tank port 49, 50 formed in its valve body 37, respectively, and its power cylinder. The outer peripheral surface is provided with ring grooves 56 and 57 that form a spool oil chamber that is switched and connected to the bow) 47 and 48.

Further, the hollow spool 38 has a reaction pressure supply communication port 58 that connects the reaction chamber 53 to the reaction pressure supply port 51 and a reaction pressure relief side that connects the reaction chamber 53 to the reaction pressure relief port 52. A communication port 59 is provided.

The spool shaft 39 has one end extending through the hollow spool 38 such that the spool 38 slides back and forth within the valve bore 45.
A pair of spool stops 60, 61 are provided at both ends of the spool 38 to fix the spool 38, and the other end is pin-coupled to the input shaft. Of course, that spool
Shaft 39 may be connected to its input shaft via a ball joint.

Furthermore, to explain the fixing structure of the spool 38 in detail, the spool shaft 39 is fitted with a sleeve fitted to one end side of the spool shaft 39 so as to be positioned between the spool shafts 7360.61. The spool shaft 39 is secured by a shaped spacer 62 and a nut 63 threadably coupled to one end of the spool shaft 39.
The spool 38 is fixed to the spool shaft 39 by clamping the spool 38 between a pair of spool stoppers 60, 61 fixed to one end of the shaft 39.

The spool stopper 60, 61 is formed into a plate shape, and has two small holes 64 opened in the stopper surface at predetermined positions and spaced apart from each other by a predetermined distance.

The reaction piston 40.41 is reciprocally slidably fitted in the piston bore 54.55 and in the spacer 6.2 on the spool shaft 39;
A reactive chamber 53 formed inside the hollow spool 38 is closed.

The pair of reaction piston stoppers 42.4
3 consists of two pins protruding from both inner end faces of the valve bore 45, the pins 42, 43 passing through the small holes 64 of the spool stoppers 60, 61,
abutting the tip against the corresponding reaction piston 40.41 to restrict movement of the reaction piston 40.41 toward the inner end surface of the valve bore 45;
With the movement of the spool shaft 39, in cooperation with the reaction spring 44, a pumping action is applied to the reaction pistons 40, 41,
The oil filled in the reaction chamber 53 is compressed to change the hydraulic reaction force felt on the spool shaft 39.

The reaction spring 44 is arranged between the reaction pistons 40.41 and around the spacer 62 on the spool shaft 39;
It imparts a pumping action to its reaction piston 40,41 and also functions as a neutral spring for the valve.

In this control valve 14, since the power steering 10 is configured as an integral type, the reaction piston 40.41 and the piston that fit the reaction piston 40.41 so as to be able to reciprocate and slide. The bores 54,55 are made of the same size and shape, but if the power steering 10 is configured as a linkage type, the reaction pistons 40,41 are of a large diameter and a small diameter. The piston bores 54 and 55 are also correspondingly formed into a large diameter bore and a small diameter bore, so that when the linkage type power steering is retracted, the steering feels heavy to the driver, and When the linkage-type power steering extends, it is avoided that the driver feels that the steering is light, or in other words, there is no difference in left and right operating force. That is, such a simple change makes it possible to equalize the steering forces for right and left turns, making it easily applicable to linkage type power steering.

The reaction pressure supply passage 16 is formed in the valve body 37 of the control valve 14 and has one end connected to the supply hydraulic piping 21 on the outlet side of the flow control valve 13 for supplying the reaction pressure of the control valve 14. The other end is connected to the supply port 51 respectively, and as such, its reaction pressure supply port 5
1 is connected to the discharge side of the oil pump 12, and the pressure oil discharged from the oil pump 12 and whose flow rate is adjusted by the flow control valve 13 is transferred to the control valve 14 and the reaction chamber 53.
We are making it possible to supply. Of course, the reaction pressure supply passage 16 may be constructed of piping.

The reaction pressure relief passage 17 is formed in the valve body 37 of the control valve 14 and is connected to the reaction pressure relief port 5 of the control valve 14.
2, its control valve bypass 36
The return side hydraulic piping 2 on the upstream side of the connection point of
2, and as such connect its reaction pressure relief port 52 to its oil reservoir 15 side to drain the pressure oil in the reaction chamber 53 of its control valve 14 to its oil reservoir. 15
I'm trying to get away from it. Of course, the reaction pressure relief passage 17 may be constructed of piping, as in the case of the reaction pressure supply passage 16.

The reaction pressure supply side variable throttle 18 is configured to change the cross-sectional area of the passage at the same time as being opened and closed by an electric actuator 65. The pressure oil flowing from the oil pump 12 to the reaction chamber 53 of the control valve 14 is blocked, and the flow rate of the pressure oil can be adjusted.

The reaction pressure relief side variable throttle 19, like the reaction pressure supply side variable throttle 18, is configured to open and close by the electric actuator 66 and change the passage cross-sectional area at the same time. located in the passage 17 from the reaction chamber 53 of the control valve 14 to the oil reservoir 1
5, and also allows the flow rate of the pressure oil to be adjusted.

The input side of the control unit 20 is electrically connected to the vehicle speed sensor 6, and the variable aperture 18.
The output side is electrically connected to the electric actuator 65.66 of No. 19, and the current flowing through the electric actuator 65.66 is controlled according to the signal from the vehicle speed sensor 68, and the variable throttle 18.19 is opened and closed. , which changes the cross-sectional area of the passage, is mainly composed of an input and output circuit, a memory circuit, an arithmetic circuit, a control circuit, and a power supply circuit, and the power supply circuit shares the battery 67 of the truck.

The vehicle speed sensor 68 detects the traveling speed of the truck, and is arranged on the output shaft of a transmission (not shown) mounted on the truck.

Next, the operation of the speed-sensitive power steering 10 incorporating the control valve 14 described above will be described in relation to the running state of the trunk.Since the diesel engine is being operated, the oil pump 12 is driven, the flow rate of the pressure oil discharged from the oil pump 12 is adjusted by the flow control valve 13, and a predetermined flow rate of pressure oil flows through the supply side hydraulic piping 21, and the flow rate of the pressure oil discharged from the oil pump 12 is adjusted by the flow control valve 13. to pump port 46 of valve 14.

Pressure oil sent to the pump port 46 is routed through the return hydraulic line 22 to the tank if the hollow spool 38 is in the neutral position, as shown.
Port 49,50 returns to the oil reservoir 15 when the steering wheel is steered, via the steering shaft and the input shaft, to whichever spool shaft 39 is pin-coupled to the input shaft. If the hollow spool 38 is slid in the direction of the movement of the spool shaft 39, the pressure oil will flow into the communication passage 31, 32 in response to the movement of the hollow spool 38. It is sent to either one of the cylinder chambers 26, 27 of the power cylinder 11 through either one of them.

At the same time, the control unit 20 inputs the signal from the vehicle speed sensor 68 and controls the variable aperture 1.
8.19 to control the current flowing through the electric actuator 65.66 to change the pressure in the reaction chamber 53 of its control valve 14 and to change its steering direction.
It is ready to obtain hydraulic reaction force suitable for wheel operation, that is, steering.

If the truck is currently running at a low speed, the control unit 20 inputs a signal from the vehicle speed sensor 68, performs a comparison operation according to the input signal, and determines the output signal, that is, the output current. , the output current is applied to the electric actuator 65.6 of the reaction pressure supply side variable throttle 18 and the reaction pressure relief side variable throttle 19.
6, so the reaction pressure relief side variable orifice 1
8 is closed, and its reaction pressure supply side variable throttle 19
is opened, and the reaction pressure supply side variable throttle 19 is adjusted to a passage cross-sectional area according to the vehicle speed at that time.

Therefore, the pressure oil in the reaction chamber 53 of the control valve 14 passes through the reaction pressure relief side communication port 59, the reaction pressure relief port 52, the reaction pressure relief passage 17, and the return side hydraulic piping 22 to the oil reservoir 15. At the same time, the oil is discharged from the oil pump 12 into the reaction chamber 53 of the control valve 14, and the flow control valve 13
Some of the regulated pressure oil is
Since the reaction pressure is not supplied from the supply side hydraulic piping 21 on the outlet side of the valve 13 to the reaction chamber 53 via the reaction pressure supply passage 16, the reaction pressure supply port 51, and the reaction pressure supply side communication port 58, the reaction pressure is not supplied to the reaction chamber 53. The hydraulic pressure in the chamber 53 is adjusted to a pressure adapted to low-speed running, so that the reaction chamber 53 has an appropriate hydraulic reaction force, and accordingly the steering at low-speed running is controlled. is performed with appropriate operating force.

In this way, when driving at low speeds, the operation of the steering wheel becomes easier, and at the same time, the oil
Since the pressure oil discharged from the pump 12 and leaking through its reaction chamber 53 into its oil reservoir 15 is stopped, waste in the flow rate of pressure oil for obtaining hydraulic reaction force is avoided, resulting in , the required flow rate of pressure oil to change the hydraulic reaction force is reduced.

Of course, if the truck is steered while stopped, the traveling speed is zero, and the reaction pressure relief side variable throttle 1
9 is closed by its control unit 20, and its reaction pressure supply side variable throttle 1st is closed by its control unit 20.
It is opened by the control unit 20, and the cross-sectional area of the passage is maximized, so that cutting, cutting, closing, and recutting can be performed with appropriate operating force.

Further, if the truck is traveling at high speed, the control unit 20 inputs a signal from the vehicle speed sensor 68, performs a comparison operation according to the input signal, determines the output current, and converts the output current into the output current. Reaction pressure supply side variable throttle 18 and reaction pressure relief side variable throttle 19
Since the reaction pressure relief side variable throttle 19 is closed and the reaction pressure supply side variable throttle 18 is opened, the reaction pressure supply side variable throttle 18 is adjusted to the vehicle speed at that time. The cross-sectional area of the passage is adjusted accordingly.

Therefore, pressure is released from the reaction chamber 53 of the control valve 14 to the oil reservoir 15 via the reaction pressure relief side communication port 59, reaction pressure relief port 52, reaction pressure relief passage 17, and return side hydraulic piping 22. No oil leaks, the pressure in the reaction chamber 53 is adjusted to a pressure suitable for high-speed running, and at the same time, the reaction chamber 53 of the control valve 14 is
The oil pump 12 is discharged, and the flow
Since pressure oil whose flow rate is adjusted by the control valve 13 is supplied, a hydraulic reaction force is obtained in the reaction chamber 53, and accordingly, steering during high-speed running is controlled by a hydraulic reaction force adapted to the vehicle speed. It is done under force.

When driving at high speeds, the steering wheel becomes difficult to operate, and at the same time, the oil
Although pressure oil is discharged from the pump 12 and supplied to its reaction chamber 53, substantially no pressure oil leaks from the reaction chamber 53 into its oil reservoir 15, eliminating wasted pressure oil. flow is avoided.

Conveniences and Benefits of the Invention Based on the above, the present invention is compared to the control valve used in speed-sensitive power steering which has already been proposed and used, and the speed-sensitive power steering incorporating the control valve. In other words, the control valve used in the speed-sensitive power steering of the present invention has a valve body that is connected to the valve bore at a predetermined position.
It has a pump port opening into the bore, a pair of power cylinder ports, a pair of tank ports, a reaction pressure supply port, and a reaction pressure relief port.
A hollow spool is arranged to be able to reciprocate and slide in a valve bore of the valve body, and a reaction chamber is formed inside the hollow spool, a pair of piston bores are formed at both ends of the reaction chamber, and a reaction chamber is formed inside the valve body.・Equipped with a reaction pressure supply side communication port that communicates the reaction pressure supply port with the chamber, and a reaction pressure relief side communication port that communicates the reaction pressure relief port with the reaction chamber, and the spool shaft passes through the hollow spool. a pair of spool stops disposed at opposite ends of the spool to fixedly connect the spool so as to slide the spool back and forth within the valve bore; - The pair of reaction piston stoppers are fitted in the pair of piston bores and the spool shaft so as to be able to reciprocate and slide so as to be driven by the spool stopper in accordance with the movement of the shaft, and the pair of reaction piston stoppers are driven by the spool stopper. regulating the movement of the reaction piston toward the bore end of the bore, and
Since a reaction spring is disposed between the reaction pistons and configured, the control pulp used in the speed-sensitive power steering of this invention allows the pressure oil that provides the hydraulic reaction force to flow from the reaction chamber. There is virtually no leakage into the oil reservoir, and the required flow rate of pressure oil, which changes the hydraulic reaction force depending on the vehicle speed, is extremely small, and moreover, it is possible to optimize the steering force and drive the oil pump. Power consumption is reduced,
In addition, the speed-sensitive power steering of this invention is
The control valve is integrated into a hydraulic circuit, with a rear axle pressure supply passage connecting the rear axle pressure supply passage to the oil pump discharge side, and a reaction pressure relief passage connecting the reaction pressure relief port to the oil reservoir side. The reaction pressure supply side variable throttle is arranged in the reaction pressure supply passage, the reaction pressure relief side variable throttle is arranged in the reaction pressure relief passage, and the control unit controls the variable pressure in response to a signal from the vehicle speed sensor. Since the speed-sensitive power steering system of the present invention is equipped with a configuration that opens and closes the throttle, the required flow rate of pressure oil flowing to the control pulp in order to apply hydraulic reaction force is reduced, and the hydraulic reaction force is adjusted according to the vehicle speed. This makes it possible to obtain the optimum reaction force according to the vehicle speed, optimize the steering force, stabilize steering, relieve the driver from physical and mental fatigue caused by steering, and make driving safer. Moreover, the power consumption for driving the oil pump is reduced, the applicability to vehicles is improved, and it is very useful for vehicles.

As for the relationship between the invention and the specific examples, from the specific examples of the present invention described with reference to the drawings, various design modifications will be apparent to those who have ordinary knowledge in the technical field to which this invention pertains. Modifications and modifications may be easily made, and furthermore, the content of this invention may be essentially the same as that invention, which satisfies essentially the same problem and achieves the same effect as that invention. It would be easily replaced by an identical aspect.

[Brief explanation of drawings]

The figure is a schematic diagram showing a specific example of the speed-sensitive power steering of the present invention incorporating a control pulp used in the speed-sensitive power steering of the present invention applied to a truck. 11... Power cylinder, 12... Oil pump, 13... Flow control valve, 14...
... Control valve, 15 ... Oil reservoir, 16 ... Reaction pressure supply passage, 17 ... Reaction pressure relief passage, 18 ... Reaction pressure supply side variable restriction, 19 ... Reaction pressure relief Side variable aperture, 20...control unit.

Claims (2)

[Claims] (1) A valve bore and, at predetermined locations, a pump port, a pair of power cylinder ports, a pair of tank ports, a reaction pressure supply port, and a reaction pressure relief port opened into the valve bore. A valve body, a reaction chamber formed inside the valve body and arranged to be able to reciprocate and slide in the valve bore of the valve body, a pair of piston bores formed at both ends of the reaction chamber, A hollow spool that passes through the hollow spool and includes a reaction pressure supply side communication port that communicates the reaction pressure supply port with the reaction chamber, and a reaction pressure relief side communication port that communicates the reaction pressure relief port with the reaction chamber. and slide the spool back and forth within the valve bore.
a spool shaft having a pair of spool stops disposed at opposite ends of the spool to fixedly connect the spool; A pair of pistons
a pair of reaction pistons that are reciprocally slidably fitted into the bore and the spool shaft;
A control valve used in speed-sensitive power steering that includes a pair of reaction piston stoppers that regulate the movement of pistons, and a reaction spring that is placed between the reaction pistons. (2) A power cylinder with a pair of cylinder chambers, an oil pump, a control valve, and an oil cylinder.
In a steering device configured with a hydraulic circuit including a reservoir, the control valve has a valve bore, and a pump that opens into the valve bore at a predetermined position.
a valve body having a port, a pair of power cylinder ports, a pair of tank ports, a reaction pressure supply port, and a reaction pressure relief port; and a reaction chamber formed inside, a pair of piston bores formed at both ends of the reaction chamber, a reaction pressure supply side communication port that communicates the reaction pressure supply port with the reaction chamber, and the reaction chamber. - A hollow spool with a reaction pressure relief side communication port that communicates the reaction pressure relief port with the chamber, and a hollow spool at both ends of the spool so as to penetrate the hollow spool and reciprocate the spool into the valve bore. a spool shaft having a pair of spool stops disposed and fixedly connecting the spool; and a piston bore of the pair, the piston bore being driven by the spool stop in response to movement of the spool shaft. and a pair of reaction pistons fitted to the spool shaft so as to be reciprocally slidable, a pair of reaction piston stoppers for regulating the movement of the reaction pistons toward the bore end of the valve bore, and a pair of reaction piston stoppers for regulating the movement of the reaction pistons toward the bore end of the valve bore. The reaction spring is placed between the pistons, and the reaction pressure supply passage is placed in the piping of the hydraulic circuit that connects the oil pump and oil reservoir to the cylinder chamber of the power cylinder, and the reaction pressure supply passage is connected to the reaction pressure supply port. is connected to the discharge side of the oil pump, a reaction pressure relief passage connects the reaction pressure relief port to the oil reservoir side, and a reaction pressure supply variable restriction is disposed in the reaction pressure supply passage; A speed-sensitive power steering system characterized in that a pressure relief side variable throttle is disposed in the reaction pressure relief passage, and a control unit opens and closes the variable throttle in response to a signal from a vehicle speed sensor.