JPH0254272B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a control valve used in vehicle power steering, and more specifically, a control valve improved to be suitable for speed-sensitive, linkage-type power steering. Regarding.

Conventionally, in linkage-type power steering, the control valve has been configured as a vehicle speed-sensitive hydraulic reaction force type in order to change the reaction force, that is, the steering force, depending on the driving condition of the vehicle.
When the steering wheel is operated suddenly,
The response characteristics and stability of valves have resulted in complex structures or required compensation means.

The purpose of this invention is to improve the static, dynamic, and transient characteristics of a valve without complicating its structure, and to improve the stability of the valve, especially when the steering wheel is suddenly operated. Moreover, the present invention provides a control valve used in power steering that suppresses valve vibration and prevents the generation of noise due to the valve vibration even when switching is performed with a large stroke.

In view of the above problem, the control valve used in the power steering of the present invention includes a spool chamber, a pump port, a tank port, and a tank port opened to the spool chamber.
a valve body having a port, a pair of power cylinder ports and a reaction port, a reaction chamber bore for a reaction chamber and reciprocatingly slidably disposed in the spool chamber; a spool with a reaction communication port communicating the pump port with the reaction chamber and a reaction relief port communicating the reaction port with the reaction chamber; a spool shaft having a pair of spool stops located at opposite ends of the spool to secure the spool for sliding reciprocation within the spool;
a pair of reaction plungers slidably fitted in the bore and the spool shaft and driven by the spool stops;
A pair of plungers that regulate the movement of the plunger.
The stopper includes a reaction spring disposed between the stopper and its reaction plunger, a reaction force regulating valve disposed in the reaction passage connecting the reaction port to the suction side of the oil pump, and the spool includes a reaction spring disposed between the stopper and the reaction plunger. When switching over a large stroke, the reaction relief port is formed on the spool so that it is closed at the large stroke position of the spool, and the reaction force regulating valve is configured to release pressure from the reaction chamber depending on the speed of the vehicle. The flow of pressure oil escaping to the suction side of the oil pump is throttled and adjusted to vary the reaction force generated by the pressure oil in the reaction chamber, and the spool is controlled by the steering wheel. When switching suddenly with a large stroke, the reaction relief port is closed at the large stroke position of the spool, and the reaction chamber functions as a damper chamber to suppress valve vibration.

Hereinafter, specific examples of the control valve used in the power steering of the present invention will be described with reference to the drawings.

The figure shows the control system of the present invention applied to constitute a speed-sensitive, linkage-type power steering system 50 for a cab-over type truck.
This shows ten specific examples of valves.

The control valve 10 is connected to a link arm (not shown) via a drag link (not shown) for front wheel steering.
a cylinder body 11 pivotally connected to a lever (not shown); a power piston 58 disposed reciprocally slidably in a cylinder bore 57 of the cylinder body 11; It is incorporated into a power cylinder 50 consisting of an operating rod 59 that is fixed and the other end is pivotally connected to the chassis side, and the compensating
The valve is operated by the steering wheel via a rod (not shown), a pittman arm (not shown), and a manual steering gear box (not shown). In the hydraulic circuit, the oil pump 5 is arranged in hydraulic pipes 54 and 55.
Pressure oil is discharged from the power cylinder 5 and the flow rate is adjusted by the flow control valve 53.
0 and also returns the pressure oil worked in the power cylinder 50 to the suction side of the oil pump 52.

That is, the control valve 10 is
A spool chamber 19 and a pump port 2 open to the spool chamber 19
0, tank ports 23, 24, a pair of power ports
a valve body 11 with cylinder ports 21, 22 and a reaction port 25;
Its spool is equipped with a reaction chamber bore 27 for a reaction chamber 26.
a reaction communication port 30 and a reaction port 25 which are reciprocally slidably disposed in the chamber 19 and communicate the pump port 20 with the reaction chamber 26;
a spool 1 with a reaction escape port 31 that communicates with its reaction chamber 26;
2 and a pair of spool stops extending through the spool 12 and positioned at opposite ends of the spool 12 to secure the spool 12 for sliding reciprocation within the spool chamber 19. 34, 34 and its reaction chamber bore 27 at each end of its spool 12.
and a spool stopper 34 fitted to the spool shaft 13 so as to be slidable back and forth;
a pair of reaction plungers 14,15 driven at 34 and the reaction plungers 14,15 towards the ends of the spool chamber 19;
A pair of plunger stops 1 that regulates the movement of
6, 16, 16, 16, a reaction spring 17 disposed between the reaction plungers 14, 15, and a reaction passage 38 connecting the reaction port 25 to the suction side of the oil pump 52. and a reaction force adjustment valve 18 formed in the spool 12 so that when the spool 12 is switched with a large stroke, the reaction relief port 31 is closed at the large stroke position of the spool 12. It was done.

The valve body 11 was manufactured to be incorporated into the cylinder body 56 of the power cylinder 51.

In addition, the flow control valve 52
The pressure oil whose flow rate is adjusted is transferred to the power cylinder 5.
The pump port 20 formed in the valve body 11 for supplying the cylinder chambers 60, 61 of 1 is connected to the supply side of the hydraulic line 54 and to the power cylinder port 2.
1 and 22 are on the cylinder side of the hydraulic pipes 54 and 55,
Furthermore, the tank ports 23 and 24 are connected to the hydraulic piping 55, respectively.

The spool 12 has a reaction chamber bore 27 for a reaction chamber 26.
is arranged in the spool chamber 19 so as to be able to slide back and forth, and the reaction chamber 2
6 can be formed.

The spool 12 also has a large diameter plunger bore 38 at one end of the reaction chamber bore 27.
A small diameter plunger bore 29 is formed at the other end of the bore 27, and a reaction communication port 30 is formed to communicate the pump port 20 with the reaction chamber 26, and a reaction communication port 30 is formed to communicate the reaction chamber 26 with the reaction chamber 25. A reaction relief port 31 is provided.

The reaction relief port 31 is connected to the valve.
Reaction port 2 formed in POD 11
5 and return pressure oil from its reaction chamber 26 to the suction side of the oil pump 52,
Also, at that time, the reaction chamber 26
It functions as an aperture for the
It turns chamber 26 into a damper chamber.
When the spool 12 is switched with a large stroke, in other words, during a large stroke of the spool (maximum stroke), the spool 12 is disconnected from the reaction port 25 and in the closed position. has been done.

In this way, the reaction relief port 31 is
It is positioned on the spool 12 in association with its reaction port 25.

Further, the spool 12 connects the pump port 20 to the power cylinder port 21,
It is provided with ring grooves 32 and 33 that form a spool oil chamber that is switchably connected to the spool 22.

The spool shaft 13 extends one end into the spool 12 and is positioned at each end of the spool 12 to allow the spool 12 to slide back and forth within the spool chamber 19 to secure the spool 12. A pair of spool stoppers 34 are provided, and the other end is provided with a compensating spool stopper 34.
Connected to rod.

Furthermore, to explain the fixing structure of the spool 12 in detail, the spool shaft 13 has a sleeve-shaped spacer fitted to one end side of the spool shaft 13 so as to be positioned between the spool stoppers 34. 36 and a nut 37 screwed to one end of the spool shaft 13.
The spool 12 is clamped between a pair of spool stoppers 34 fixed to one end side of the spool 3, and the spool 12 is fixed.

These spool stoppers 34 are formed in the shape of a plate, and are spaced apart from each other at a predetermined distance.
Two small holes 35 are opened in the stopper surface at predetermined positions.

The reaction plungers 14 and 15 are
The large diameter reaction plunger 14 is formed into one large diameter and one small diameter, and is reciprocally slidably fitted into the large diameter plunger bore 28 and the spacer 36 on the spool shaft 12;
The small diameter reaction plunger 15 is reciprocally slidably fitted into the small diameter plunger bore 29 and a spacer 36 on the spool shaft 13 to close a reaction chamber 26 formed within the spool 12.

As such, reaction plunger 14,
15 is designed to have a large diameter and a small diameter, in this power steering 50, when the power cylinder 51 retracts, the driver feels that the steering is heavy, and the power cylinder 51 When the steering wheel 51 extends, the driver feels that the steering is light, in other words, there is a difference in the left and right operating forces, so it is necessary to equalize the steering forces for right and left turns.

The pair of plunger stops 16 each consist of two pins protruding from both inner end surfaces of the spool chamber 19, and these pins pass through small holes 35 in the spool stopper 34 and have corresponding large and small diameters. reaction plunger 1
4 and 15 to restrict the movement of the reaction plungers 14 and 15 toward the inner end surface of the spool chamber 19, and as the spool shaft 13 moves, the reaction spring 17 These reaction plungers 14 and 15 are cooperated to provide a pumping action to the reaction chamber 19.
This compresses the oil filled with oil and changes the reaction force felt on the spool shaft 13.

The reaction spring 17 is disposed between the reaction plungers 14, 15 and around the spool shaft 13, ie, the spacer 36, to impart a pumping action to the reaction plungers 14, 15 and to provide a pumping action to the reaction plungers 14, 15. It functions as a neutral spring for

The reaction force regulating valve 18 is connected to a reaction passage 38 consisting of piping connecting the reaction port 25 of the valve body 11 to the hydraulic piping 55.
is arranged in the reaction chamber 26 to adjust the amount of oil that releases the pressure oil in the reaction chamber 26 to the suction side of the oil pump 52.
The valve is provided with a spool chamber (not shown) and a pair of ports 39 and 40 connected to the spool chamber. a body, and a spool (not shown) that is reciprocally slidably disposed within the spool chamber and changes the cross-sectional area of the passage within the spool chamber in response to the reciprocating sliding movement, and the track travels at a speed of , the spool is slid back and forth within the spool chamber to change the cross-sectional area of passage within the spool chamber and to open the ports 39, 40.
Adjust the flow rate of pressure oil flowing between spool 1
The reaction chamber 26 is configured to vary the reaction force generated by the pressurized oil in the reaction chamber 26 of the second reaction chamber 26.

To be more specific, this reaction force adjustment valve 18 is designed to widen the passage cross-sectional area when the truck is traveling at low speed, and to narrow the passage cross-sectional area when the truck is traveling at high speed. , which slides the spool back and forth, and the spool is also connected to an actuator, such as a servo.
The servo motor is configured to be driven in response to a signal from a vehicle speed sensor (not shown).

Next, the control configured as described above.
Valve 10 and its control valve 10
To describe the operation of the power steering 50 incorporating the power steering system 50 in accordance with the driving conditions of a cab-over type truck, if the internal combustion engine is currently being operated, the oil pump 52 is driven; The pressure oil supplied from the flow
The flow rate is adjusted by the control valve 53, and the flow rate of the predetermined pressure oil is adjusted by the control valve 1.
0 pump port 20.

As shown in the figure, if the spool 12 is placed in the neutral position, the pressure oil sent to the pump port 20 will mainly flow from the tank ports 23 and 24 through the hydraulic piping 55. It is returned to the suction side of the pump 52, but the steering
As the wheel is steered, its spool shaft 13 is pushed or pulled in either direction via the manual steering gear box, pitman arm, and compensating rod, causing the spool 12 to move along its spool shaft 13. According to the movement of the spool 12, the pressure oil passes through the cylinder side of the hydraulic piping 54, 55 and is applied to either of the cylinder chambers 60, 61 of the power cylinder 51. One of the signals is sent to the reaction chamber 26.

The reaction force to the steering is provided by the pressure in the reaction chamber 26 and the reaction spring 17.

In such operation of power steering 50, if the truck is driven at low speed,
In response to a signal from the vehicle speed sensor, the servo motor is driven to slide the spool of the reaction force regulating valve 18, making the passage area in the spool chamber relatively wide.

Therefore, the oil in the reaction chamber 26 flows smoothly to the reaction relief port 31 and the reaction port 25, and then to the suction side of the oil pump 52 via the reaction passage 38, so that the oil in the reaction chamber 26 flows smoothly into the reaction chamber 26. The oil in 26 does not provide much resistance to the sliding of reaction plunger 14 or 15;
Steering during low-speed driving is performed with a small amount of operating force.

Of course, if the truck is steered while stopped, the traveling speed is zero and the passage cross-sectional area of the reaction force regulating valve 18 is maximized, so that the pressure in the reaction chamber 26 reaches atmospheric pressure. The condition is close to that of the previous one, and operations such as turning, closing, and turning back can be performed with extremely small operating force.

Additionally, if the truck is running at high speed, the servo motor is driven in response to a signal from the vehicle speed sensor, and the spool of the reaction force adjustment valve 18 is slid, causing the cross-sectional area of the passage in the spool chamber to has been narrowed.

Therefore, the oil in the reaction chamber 26 becomes more difficult to return to the suction side of the oil pump 52 due to the restriction of the reaction force regulating valve 18, so that the oil in the reaction chamber 26 , reaction plunger 14 or 1
This results in a large resistance to the sliding movement of the wheel 5, and as a result, steering during high-speed running is performed with a relatively large operating force. In this way, a relatively large amount of operation is required for steering during high-speed driving, and driving stability is improved.

The power steering 50 is operated as described above when the truck is running at low speeds, at high speeds, or when the truck is stationary. Therefore, when the power cylinder 51 in the power steering 50 contracts and extends, the difference between the operating force for turning to the right and the operating force for turning to the left becomes extremely small. The steering force for turning and turning to the left is equalized. As a result, the power steering system 50 relieves the driver from physical fatigue caused by truck steering.

Further, when the power steering 50 performs the above-mentioned operation when the truck is running at low speed, high speed, or when the truck is stationary, the steering wheel is suddenly switched and operated, and the spool 12 is suddenly moved with a large stroke. When the spool 12 is switched to a large stroke (maximum stroke), the reaction relief port 31 is closed, and the reaction port 2 is closed.
5, its reaction chamber 26 becomes a damper chamber, and its reaction chamber 26 is forced into contact with the spool 12 which is switched abruptly with such large strokes.
absorbs great force. As a result, the vibration of the spool 12 that would occur at that time is suppressed, and the vibration damping effect of the valve itself prevents the generation of noise due to the valve vibration.

In the above-mentioned specific example 10, the reaction force adjustment valve 18 is
It was explained that the amount of throttle is adjusted according to the traveling speed of the cab-over type truck, that is, the vehicle speed, but the configuration is such that the amount of throttle is adjusted according to the rotational speed of the internal combustion engine mounted on the truck. It is also possible.

In that case, the servo motor that drives the reaction force regulating valve 18 will be driven by a signal from an engine speed sensor located in the transmission.

Also, as previously discussed, the reaction communication and relief ports 30, 31 of the control valve 10 with a single reaction chamber 26
has two reaction chambers on both sides of the spool.
6, in which case both reaction chambers are connected to each other by a communication passage, in which a reaction force regulating valve 1 is provided.
8 to adjust the reaction force, the reaction relief port 31 is applied to the port that connects the reaction chamber 26 to the communication chamber.

As understood from the above, the control valve used in the power steering of the present invention includes a spool chamber, a pump port, a tank port, and a pair of power ports opened to the spool chamber. Cylinder·
a valve body having a pump port and a reaction port, a reaction chamber bore for a reaction chamber and reciprocatingly slidably disposed in the spool chamber; a spool passing through the spool and having a reaction communication port communicating with the reaction chamber and a reaction relief port communicating the reaction port with the reaction chamber;
a spool shaft having a pair of spool stops positioned at opposite ends of the spool to secure the spool so as to slide the spool back and forth within the spool chamber;
At each end of the spool, the spool is reciprocally slidably fitted into the reaction chamber bore and spool shaft.
a pair of reaction plungers driven by stoppers; a pair of plunger stoppers for regulating movement of the reaction plungers toward the ends of the spool chamber;
a reaction spring disposed between the plungers and a reaction force regulating valve disposed in the reaction passage connecting its reaction port to the suction side of the oil pump; , since its reaction relief port is closed at the large stroke position of the spool,
In the control valve used in the power steering of this invention, when the steering wheel is suddenly switched and operated, and the spool is suddenly switched with a large stroke,
The reaction relief port is closed at the large stroke position of the spool, in other words, near the maximum stroke, and the reaction chamber functions as a damper chamber, and the large force of the spool is absorbed by the reaction chamber. As a result, the vibration of the spool is suppressed, so-called valve vibration is suppressed, and the generation of noise due to the valve vibration is prevented, thus improving the static, dynamic and transient characteristics of the valve. The stability of the valve is improved, and the reaction force regulating valve throttles and adjusts the flow rate of pressurized oil escaping from the reaction chamber to the suction side of the oil pump depending on the vehicle speed. As a result, the reaction force generated by the pressure oil in the reaction chamber is changed, that is, the optimum reaction force is obtained depending on the driving condition of the vehicle, and the steering is stabilized. This reduces steering fatigue and makes the vehicle safer to drive.

As mentioned above, from the specific examples of the present invention explained with reference to the drawings, those who have ordinary knowledge in the technical field to which this invention pertains will understand the following:
Various design modifications and changes can be easily made, and furthermore, the content of this invention is essential to the realization of the invention that accomplishes the task of the invention,
It is derived from the technical essence of the invention, which is the nature of the invention, and can be easily replaced by an embodiment that is objectively recognized as incorporating it.

[Brief explanation of drawings]

The figure is a schematic diagram showing a specific example of the control valve of the present invention applied to a speed-sensitive linkage type power steering system for a cab-over type truck. 10... Control valve, 11... Valve body, 12... Spool, 13... Spool shaft, 14, 15... Reaction plunger, 16... Pair of plunger stops, 17... Reaction spring , 18...
...Reaction force adjustment valve, 30... Reaction communication port, 31... Reaction relief port, 50...
Power steering, 51... Power cylinder, 52... Oil pump, 53... Flow
control valve.

Claims (1)

[Claims] 1. A spool chamber and a pump port opened in the spool chamber;
Valve with tank port, pair of power cylinder ports and reaction port.
a reaction chamber having a reaction chamber bore for a reaction chamber and reciprocatingly slidably disposed in the spool chamber and communicating the pump port with the reaction chamber; - a spool with a reaction relief port communicating the port with the reaction chamber; and a spool positioned at each end of the spool to extend through the spool and slide the spool back and forth into the spool chamber. a spool shaft having a pair of spool stops for securing the spool;
a pair of reaction plungers driven by stoppers; a pair of plunger stoppers that restrict movement of the reaction plungers toward the ends of the spool chamber; a reaction spring disposed between the reaction plungers; It consists of a reaction force adjustment valve placed in the reaction passage that connects the reaction port to the suction side of the oil pump, and controls the pressure oil flowing from the oil pump to the power cylinder.The spool has a large stroke. A control valve used in power steering that is characterized by its reaction relief port being closed at the large stroke position of the spool when the spool is switched.