JPH0216940Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Field of Application of the Invention] This invention relates to a reaction force adjusting device for automatically controlling a steering reaction force in proportion to vehicle speed in a power steering system.

[Background of the invention] A reaction force device is attached to the power steering device so as to give an appropriate steering sensation to the driver. In general, steering resistance is greatest when the vehicle is stationary, so-called stationary steering, and becomes extremely small when the vehicle is running at high speed. Therefore, when traveling at high speeds, there is almost no need for the power steering device to function, and for this purpose the reaction force device as described above is provided.
However, it is clear that if the reaction force is too large, it will cause inconvenience when the station is stationary, and in order to balance these two, the steering system as shown in Japanese Patent Publication No. 56-42507 was used to set an appropriate reaction force value. A reaction force control device that can automatically adjust a reaction force value according to resistance has been proposed.

In this conventional automatic reaction force adjustment device, as shown in FIG. , 8B are formed in the spool 2 so that the supply pressure from the pump port 12 to the power cylinder is not affected by the pressure in the reaction force chambers 4A, 4B, or furthermore, in the reaction force chambers 4A, 4B. Fixed orifices 10, 10A and 10B are provided in the passages 8A and 8B, respectively, so that the pressure can be controlled to zero. However, it is very difficult to form fixed orifices 10 with exactly the same opening area in both passages 8A, 8B, and because the opening areas of the orifices 10A, 10B are different, the pressure in the reaction chambers 4A, 4B is not necessarily uniform. Therefore, there was a drawback that the balance between left and right steering became poor. Further, it was difficult to form the passage 8 and the orifice 10 in the valve spool 2, resulting in poor workability.

In addition, in FIG. 4, the reference numeral 14 indicates the reaction force chamber 4.
A pressure control valve equipped with a variable orifice mechanism is provided in the middle of the passage extending from A, 4B to the tank port 16, so that the pressure in the reaction force chambers 8A, 8B can be controlled by changing the passage opening area according to the vehicle speed. It's summery.

[Purpose of the invention] The present invention was made in view of the problems of the prior art described above, and its purpose is to provide a reaction force adjustment device with excellent left and right steering balance.

[Summary of the invention] The automatic reaction force adjustment device according to the invention forms a communication passage that communicates both reaction force chambers in the valve housing, and connects a pressure oil source to this communication passage through a single fixed orifice. It is characterized by introducing high pressure, which keeps the pressure in both reaction force chambers the same at all times, so the steering force in both left and right directions is balanced, further improving driving stability. It is. Also, since there is no need to provide a passage for supplying pressure oil to the reaction force chamber in the valve spool,
The processability of the device is also excellent.

[Embodiment of the invention] Next, an embodiment of the invention will be described based on the drawings.

FIG. 1 shows the implementation of the invention.

The automatic reaction force adjustment device according to the present embodiment moves by steering the steering shaft to connect the power cylinder (not shown) to the power cylinder (not shown).
Valve spool 30 that switches the direction of pressure oil supply to
and a pump 80 formed at both ends of the valve spool.
A power cylinder control valve mechanism 20 includes a reaction force chamber 50 that is supplied with pressure oil to suppress movement of the spool 30, and an oil tank 8 from the reaction force chamber 50.
2, and a reaction force control valve 70 that controls the pressure inside the reaction force chamber 50 based on a signal from a controller 84.

The steering wheel of the vehicle is connected to a pinion shaft 22 via a steering shaft (not shown), and a pinion (not shown) is fixed to the pinion shaft 22. A pinion-engaging rack (not shown) extends perpendicular to pinion shaft 22 and is connected to a piston within the power cylinder. The piston in the power cylinder is connected to the tie rod of the wheel, and when the handle is operated, a rack is slid through the pinion shaft 22 to steer the wheel.

A pinion shaft 22 is disposed passing through the valve housing 24. A spool insertion hole 32 is formed in the valve housing 24 in a direction perpendicular to the pinion shaft 22, and a valve spool 30 is inserted into the spool insertion hole 32. It is arranged so that it can slide. A pin hole 34 passing vertically is formed in the valve spool 30, and the pin hole 34 and the pinion shaft 22 are connected by a swing lever 28. The swing lever 28 is configured to be able to swing in the left-right direction in FIG. 1 about a lower end fulcrum 29, and the valve spool 30 is designed to slide in the left-right direction by swinging the swing lever 28. A pump port (not shown) is provided on the inner peripheral surface of the spool insertion hole 32, and cylinder ports 35, 3 are provided on both sides of the pump port.
9 and a tank port 37 are provided, high pressure fluid is supplied from a pump 82 to the pump port, and fluid is discharged from the tank port 37 to the oil tank 82.

On the other hand, an annular groove 38 is formed on the outer peripheral surface of the valve spool 30 at a position facing the pump port, and high-pressure oil is selectively supplied to the cylinder port 35 or 36 through this annular groove 38, thereby generating power. The cylinder is now activated.

A reaction force chamber 50 is provided at both ends of the valve spool 30.
50A and 50B are formed, and the valve housing 2
A communication path 40 is formed in the spool insertion hole 4, which extends parallel to the spool insertion hole 32 and communicates the reaction force chambers 50A, 50B. An open passage 42 extending into the annular groove 38 of the valve spool 30 is formed in the communication passage 40, and pressure oil is supplied from the pump port to the reaction force chambers 50A and 50B via the annular groove 38, the passage 42, and the communication passage 40. supply is becoming available. Further, a fixed orifice 43 is provided in this passage 42, so that the pressure in the reaction force chamber 50 can be controlled to zero, and the pressure in the power cylinder is not affected by the pressure in the reaction force chamber 50. It seems like there is no such thing.

A piston 46 is provided in the reaction force chambers 50, 50A, and 50B.
are built in and pressed against the spool side by the spring 44, but the reaction force chamber 50
has a larger diameter than the spool insertion hole 32, and the piston 46 cannot enter into the spool insertion hole 32, and in the neutral state shown in FIG. It is designed so that it does not affect 30.

An oil tank 82 is located approximately in the center of the communication path 40.
A passage 86 that serves as an oil return path is provided. A proportional solenoid pressure control valve 70 that can control the opening area of the passage is installed in this passage. The fluid passage of this pressure control valve 70 has an automatically variable orifice 72 that changes the opening depending on the vehicle speed.
is formed. This automatic variable orifice 72
In this method, a constriction part 74 is provided in a fluid passage in which the fluid inlet and outlet are perpendicular to each other, and a portion 76A of the pilot spool 76 facing the constriction part 41 is formed into a conical shape, and the solenoid 77 is excited. The operation causes the pilot spool 76 to slide together with the sliding shaft 78, thereby making it possible to change the fluid passage opening area of the throttle portion 74. This pressure control valve 70 is connected to a controller 84, and the controller 84 is connected to a vehicle speed sensor 88 attached to, for example, a propeller shaft. The proportional solenoid 77 changes the passage opening area in proportion to the vehicle speed in response to a signal from the controller 84, thereby adjusting the pressure inside the reaction force chambers 50A and 50B.
As shown in the figure, the steering torque/power cylinder output characteristics are controlled according to the vehicle speed. That is, in FIG. 3, the vertical axis shows the output P of the power cylinder and the horizontal axis shows the steering torque T. The larger the degree V (V ₁ <V ₂ ...Vn), the more △ The pressure inside the reaction force chamber 50 is controlled by the reaction force control valve 70 so that P/ΔT becomes small.

Next, the operation of the automatic reaction force adjustment device according to this embodiment will be explained.

When the handle is now rotated to the right (in the direction of arrow A in Figure 1), the pinion shaft 22 tries to displace along the rack in the opposite direction to the direction of movement of the rack due to the large resistance of the rack, and moves the swinging lever 28 to the fulcrum 29. Swing in the same direction (direction of arrow B) around . This causes the valve spool 30 to move in the same direction (direction C).
The pump port and cylinder port 36 communicate with each other via the annular groove 38, and pressurized oil from the pump 80 is supplied to the power cylinder to generate assist force.

At the same time, both reaction force chambers 50A and 5 are connected via the communication path 40.
High-pressure fluid acts on 0B, and the valve spool 30 receives the reaction force of the high-pressure fluid in the reaction force chamber 50B. By the way, since this fluid flows back to the tank side via the variable orifice 72, the fluid pressure acting on the end face of the valve spool 30 as the above-mentioned drag force is determined by the fluid pressure ratio between the fixed orifice 43 and the variable orifice 72. becomes. This drag force is fed back as a valve reaction force through other components such as the swing lever 28, the pinion shaft 22, and the handle, in order to give the driver a steering sensation.

By the way, turning while the vehicle is stopped, that is,
When the vehicle is stationary, there is no input from the vehicle speed sensor 88 via the controller 84, so the solenoid 7
7 is not excited and the pilot spool 76 is not displaced. Therefore, the opening area of the automatically variable orifice 72 becomes sufficiently large, so that the reaction force chambers 50A and 50B
The fluid pressure inside the valve spool 30 is very small, so the reaction force that the valve spool 30 receives is also small, and the stationary steering force is just the right amount of light due to the power steering.

When the vehicle starts running, the vehicle speed is detected by the vehicle speed sensor 88 and an excitation signal is sent to the solenoid 77 via the controller 84. The excitation current sent from the controller 84 to the solenoid 77 increases in proportion to the vehicle speed.

Due to the excitation action of the solenoid 77, the sliding shaft 78
Together with this, the pilot spool 76 slides in the direction of the constriction portion 74, the orifice opening area decreases, and the fluid pressure within the reaction force chambers 50A, 50B increases.

In other words, when the vehicle speed increases and the ground resistance increases, if turning is performed at this time, the steering wheel will become too light due to power steering and the steering feeling will be lost, but as mentioned above, the reaction force to obtain the steering reaction force Room 50
The pressures at A and 50B increase and are fed back to the steering wheel via the swing lever 28 and other components, so that a constant, optimal steering force is always maintained depending on the vehicle speed.

Also, during high-speed operation, the automatic variable orifice 72 is fully closed, and the power cylinder control valve mechanism 2
By maximizing the supply pressure to the reaction force chambers 50A and 50B at 0, the Vn curve becomes the reaction force characteristic with the heaviest steering feel, and if necessary, this can be adjusted by manual adjustment as shown by the symbol MS in Figure 3. Of course, it is also possible to approximate the state.

In this embodiment, since the structure is such that pressure oil is supplied into both reaction force chambers 50A and 50B through one fixed orifice 43, both reaction force chambers 50A and 50B are
The pressure inside 0B is always the same, and there is no difference in the steering reaction force no matter which direction the steering is made to the left or right. As a result, stable cornering becomes possible.

Moreover, the pressure control valve 70 used in the above embodiment
Although the directions of fluid inflow and outflow are perpendicular to each other, a pressure control valve configured such that the direction of fluid inflow and outflow is the same as shown in FIG. 2 may be used. The pressure control valve 90 is configured by disposing a pilot spool 94 in a fluid passage perpendicular to the fluid flow direction, the pilot spool 94 having an annular groove 93 formed on its outer periphery facing the fluid inlet/outlet ports 91, 92, and a solenoid 95. Due to the excitation action of the sliding shaft 9
6 and the pilot spool 94 to slide the constriction portion 9 provided in the annular groove 93 and the fluid inlet 91.
The fluid passage opening area with respect to 1A can be changed.

[Effects of the Invention] As is clear from the above explanation, according to the present invention, the balance performance of the steering reaction forces in the left and right directions is improved, and stable steering becomes possible. Furthermore, since there is no need to machine a pressure oil supply passage into the reaction force chamber in the valve spool, there is also the effect that the machine workability of the device is improved.

[Brief explanation of the drawing]

Fig. 1 is a schematic diagram of an embodiment of the present invention, Fig. 2 is a sectional view showing another embodiment of the pressure control valve used in the present invention, and Fig. 3 is an automatic reaction force adjustment device according to the present embodiment. FIG. 4 is a cross-sectional view of a conventional automatic reaction force adjustment device. 20...Power cylinder control valve mechanism, 30
...Valve spool, 40...Communication path, 43...
Fixed orifice, 50, 50A, 50B... Reaction force chamber, 70... Reaction force control valve with automatic variable orifice, 80... Pump, 82... Oil tank,
84...controller, 88...vehicle speed sensor.

Claims (1)

[Scope of utility model registration request] In order to obtain the steering reaction force as the valve reaction force of the control valve, reaction force chambers are provided at both ends of the valve spool, and a passage is provided to guide high pressure from the hydraulic source into the reaction force chamber through a fixed throttle when the valve spool is displaced. , and an automatically variable orifice is provided in the passage that releases the pressure oil from this reaction force chamber to the tank side, and this automatically variable orifice is linked with a control mechanism that operates by detecting the vehicle speed. In the automatic reaction force adjustment device that increases the hydraulic reaction force by restricting the pressure, the passage introducing high pressure to the reaction force chamber is formed in the valve housing as a communication passage that communicates both reaction force chambers, An automatic reaction force adjustment device characterized in that it is connected to a pump port via a fixed throttle so that high pressure from a hydraulic source is guided to this communication path.