JPH0324456Y2 - - Google Patents

Description

[Detailed Description of the Invention] (Industrial Application Field) This invention relates to a steering reaction force adjusting device that automatically adjusts the steering reaction force of a power steering in proportion to vehicle speed.

(Prior Art) A power steering system for a vehicle is equipped with a reaction force device to prevent the steering wheel from becoming too light and to provide an appropriate steering feel.

Generally, steering resistance is at its maximum when the vehicle is stationary, or when the vehicle is stationary, and becomes extremely small when the vehicle is running at high speed. Therefore, when driving at high speeds, there is almost no need to utilize the power steering function, and in fact, a reaction force device that provides an appropriate amount of steering reaction force is required to prevent the steering wheel from being turned too much.

However, if this steering reaction force is made too large, the steering wheel may become too heavy when turning stationary.Therefore, there are devices that can obtain a reaction force corresponding to the steering resistance, such as in Japanese Patent Publication No. 56-42507. It is proposed in

As shown in FIG. 5, reaction force chambers 4A and 4B are formed at both ends of the valve spool 2 of the control valve 1, and a passage 8A leads pressure oil from the pump port 12 to these reaction force chambers 4A and 4B. , 8B are formed inside the spool 2, and the pump port 1
The supply pressure from 2 to the power cylinder is transferred to the reaction force chamber 4.
In order to avoid the influence of A and 4B, the reaction force chamber 4
Fixed orifices 10A and 10B are provided in passages 8A and 8B so that the pressures in A and 4B can be controlled to zero.

A variable orifice 14 whose opening degree changes depending on the vehicle speed is installed in the middle of the passage 5 that communicates with the tank port 16 from both reaction force chambers 4A, 4B. Variable orifice 1
4 decreases the opening degree to increase the hydraulic reaction force of the reaction force chambers 4A and 4B, and conversely, when the vehicle speed decreases and, for example, when the vehicle is stationary at a stop, the orifice opening degree is maximized to eliminate the hydraulic reaction force. It can be done.

In this way, it is possible to apply an appropriate steering reaction force in response to the steering resistance, but in this case, the fixed orifices 10 of both passages 8A, 8B
It is very difficult to form the opening areas of A and 10B to be exactly the same, and because the opening areas of the orifices are different, the pressure generated in the reaction force chambers 4A and 4B is not necessarily uniform, so the left and right steering balance is affected. Also, if the valve spool 2 has such passages 8A, 8B and orifice 10,
Forming A and 10B also deteriorates workability.

As a solution to such problems, Jitsuganaki
No. 59-123157 is proposed.

This introduces high pressure into the reaction force chambers at both ends of the valve spool through a single fixed restrictor that communicates with the pump port when introducing pressure oil from the pump port through a communication path formed in the valve housing. In this case, since there is no variation in the area of the orifice as described above, it is possible to obtain a uniform steering reaction force on the left and right sides.

(Problems to be Solved by the Invention) However, when the hydraulic fluid passes through this fixed throttle formed in the valve housing, a fluid sound called "shu" may be generated.

This may or may not occur depending on the velocity of the flow through the fixed restrictor and whether the flow is turbulent or laminar. Therefore, basically, fluid sound can be eliminated by lowering the flow velocity so that the fluid passing through the fixed throttle becomes laminar, but this is not always possible due to the pressure generated in the reaction force chamber and the required flow rate. It is not possible to maintain the flow within the laminar flow region, and therefore, depending on the operating conditions, fluid noise may be generated, which may be harsh to the ears.

The present invention was proposed to solve such problems.

(Means for Solving the Problems) The present invention forms reaction force chambers at both ends of the valve spool of the control valve, and provides a passage in the reaction force chambers for guiding high pressure from a hydraulic source through a fixed throttle. An automatic variable throttle is provided in the passage that releases pressure oil from this reaction chamber to the tank side, and a control mechanism is provided to increase or decrease the opening degree of this automatic variable throttle in accordance with the vehicle speed. In a steering reaction force adjustment device for power steering that throttles the opening and increases hydraulic reaction force, a passage is formed in the valve housing to lead high pressure to the reaction force chamber, and this passage is connected to the pump port via the fixed throttle. A noise-reducing rectifying member is interposed in this fixed diaphragm.

(Function) Therefore, the fluid passing through the fixed throttle is rectified by the noise-reducing rectifier, and therefore even if the flow rate fluctuates or the downstream pressure changes, there will be no difference as the fluid passes through the orifice. It is possible to reliably prevent the generation of sound.

(Example) Examples of the present invention will be described below based on the drawings.

As shown in FIG. 1, a control valve 20 that selectively supplies pressure oil to a power cylinder (not shown) by operating a steering shaft includes a valve spool 30 that switches the direction of pressure oil, and a control valve 20 formed at both ends of the valve spool 30. The reaction force chambers 50, 50A, and 50B are provided with pressure oil from the pump 80, and are interposed in the passage from the reaction force chamber 50 to the oil tank 82, and the opening degree is increased or decreased by a signal from the controller 84. and an automatic variable throttle (reaction force control valve) 72 that controls the pressure in the reaction force chamber 50.

The steering wheel of the vehicle is connected to a pinion shaft 22 via a steering shaft (not shown), and a pinion that meshes with a rack (not shown) is attached to this pinion shaft 22. As the pinion shaft 22 rotates, the rack moves, and a power cylinder (not shown) moves. In conjunction with the piston, the wheel tie rods are steered. At this time, pressure oil is supplied from the control valve 20 to power assist the movement of the piston of the power cylinder.

The pinion shaft 2 passes 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 the valve spool 30 is housed in the spool insertion hole 32 in a freely sliding manner.

A pin hole 34 passing through the valve spool 30 vertically is formed, and the pin hole 34 and the pinion shaft 2 are connected to each other.
2 are connected by a swing lever 28.

This swinging lever 28 rotates around a fulcrum 29 at the lower end.
The valve spool 30 is capable of swinging in the left-right direction as shown in the figure, and the valve spool 30 slides due to this swinging.

On the inner circumferential surface of the spool insertion hole 32, a pump port (not shown) is sandwiched between cylinder ports 35 and 36.
and a tank port 37 are provided, high pressure fluid from the pump is supplied 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 pressure oil is selectively supplied from the annular groove 38 to the cylinder port 35 or 36, thereby operating the power cylinder. do.

The reaction force chambers 50 at both ends of the valve spool 30 communicate with each other via a communication passage 40 formed in the valve housing 24, and an open passage 42 facing the annular groove 38 is formed in the middle of this communication passage 40. Pressure oil from the port is supplied to both reaction force chambers 50A and 50B via a passage 42 and a communication passage 40.

A fixed orifice 43 is interposed in this passage 42 so that the pressure in the reaction force chamber 50 does not affect the power cylinder, in other words, the pressure in the reaction force chamber 50 is controlled independently of the pressure in the power cylinder. It's becoming more controllable.

As shown in FIG. 2 or 3, the opening passage 42 is provided with a rectifying collar 60 or a rectifying collar 60 located downstream of the fixed orifice 43 and close to the diffusion section 43B downstream of the constriction section 43A as a rectifying member for noise reduction. 65
is interposed.

Each of the rectifying collars 60 and 65 is composed of a bottomed cylinder whose surface facing the fixed orifice 43 is closed, and one of the rectifying collars 60 has holes 62 in the peripheral wall,
64 is formed through the rectifying collar 65, and holes 67 and 69 are formed in the bottom wall of the other rectifying collar 65.

In the embodiment shown in FIG. 2, the fluid that has passed through the fixed orifice 43 passes through the annular gap between the outer periphery of the rectifying collar 60 and the inner periphery of the open passage 42, and is rectified by passing through the holes 62 and 64. The outbreak is being controlled.

Further, in the embodiment of FIG. 3, the fixed orifice 43
The flow is rectified by passing through the holes 67 and 69 from the throttle part 43A, and the generation of abnormal noise can also be suppressed.

Note that the rectifying collar is not limited to the shapes shown in FIGS. 2 and 3, but may have any shape as long as it produces a rectifying effect.

A piston 46 is incorporated in each of the reaction force chambers 50, 50A, and 50B, and is pressed against the end face of the valve spool 30 by a spring 44, but the reaction force chamber 50 has an inner diameter larger than that of the spool insertion hole 32. Therefore, the piston 46 cannot enter the spool insertion hole 32, and in the valve neutral state as shown in FIG. It's summery.

A return passage 86 extending to the oil tank 82 is provided approximately in the center of the communication passage 40 . An automatically variable orifice (variable throttle) 72 driven by an electromagnetic solenoid 70 is interposed in the middle of this passage 86, and the opening degree of the orifice is increased or decreased depending on the vehicle speed.

In other words, the automatically variable orifice 72
The tapered portion 76A of the pilot spool 76, which is facing toward the center, is pushed out via the rod 78 by the excitation of the solenoid coil 77, thereby changing the orifice opening area.

The electromagnetic solenoid 70 is controlled by a signal from a controller 84, and the controller 84 reduces the opening degree of the automatically variable orifice 72 in accordance with an increase in vehicle speed based on the output of a vehicle speed sensor 88 that detects the rotation of the propeller shaft, for example. Reaction force chamber 50
The pressure of A and 50B is increased.

In Figure 4 _, the vertical axis shows the output P of the power cylinder, and the horizontal axis shows the steering torque _T on _the steering wheel side.
The pressure in the reaction force chamber 50 is controlled so that ΔP/ΔT becomes small.

Next, to explain the overall operation, when the handle is now rotated in the direction A in Fig. 1, the resistance of the rack is large, so the pinion shaft 22 tries to move in the direction opposite to the rack along the direction of the rack. , the swing lever 28 is rotated in the direction B about the fulcrum 29.

As a result, the valve spool 30 moves in the C direction, the pump port communicates with the cylinder port 36 via the annular hole 38, pressure oil from the pump 80 is supplied to the power cylinder, and at the same time, return oil is transferred to the other cylinder. The oil is discharged from the port 35 to the oil tank 82 via the tank port 37, and the power cylinder assists the steering wheel operation with power.

At this time, pressure oil is introduced from the fixed orifice 43 to both reaction force chambers 50A and 50B via the communication path 40, and the valve spool 30 receives resistance from the reaction force chamber 50B.

By the way, this pressure oil is automatically variable orifice 72.
The fluid pressure generated in the reaction force chamber 50B corresponds to the pressure ratio regulated by the fixed orifice 43 and the variable orifice 72, and the fluid pressure generated in the reaction force chamber 50B corresponds to the pressure ratio regulated by the fixed orifice 43 and the variable orifice 72.
The pressure in the reaction force chamber 50B decreases as the opening degree of 2 increases.

This hydraulic reaction force acting on the valve spool 30 is fed back to the steering wheel via the swing lever 28, pinion shaft 22, etc. as a steering reaction force.

When performing stationary turning with the vehicle stopped, the controller 8
4 does not energize the electromagnetic solenoid 70, so the opening degree of the automatically variable orifice 72 becomes the maximum, and therefore the reaction force acting on the reaction force chambers 50A, 50 takes the minimum value, resulting in a large steering resistance during stationary turning. The power-assisted steering wheel has a moderately light operating force.

When the vehicle is running, a signal corresponding to the vehicle speed is input to the controller 84, and the controller 84 excites the electromagnetic solenoid 70 in accordance with the vehicle speed. Therefore, the opening degree of the automatically variable orifice 70 decreases depending on the vehicle speed, and the pressure in the reaction chambers 50A and 50B increases.

Generally, the ground resistance of the wheels tends to decrease as the vehicle speed increases, and the steering resistance becomes smaller as the vehicle speeds up. Therefore, in such a case, the power assist makes the steering wheel too light and the steering feeling is lost, but as mentioned above, the reaction force chamber 50
By increasing the hydraulic reaction forces of A and 50B, a moderate amount of steering torque can be applied.

Note that when the opening degree of the automatically variable orifice 72 is maximized at high speed, a heavy steering feeling is obtained as shown in FIG. 4, and in some cases, a state close to manual steering can be achieved as shown by MS.

On the other hand, when pressure oil flows into the reaction force chambers 50A and 50B via the fixed orifice 43, the fluid that became high speed when passing through the orifice is rectified by passing through the rectifying collar 60 or 65, so that the fixed orifice 43 No abnormal noise is generated in the downstream section.

The flow rate passing through the fixed orifice 43 changes depending on the design conditions of the power steering, but by installing the rectifying member downstream of the fixed orifice 43 in this way, the passing fluid is always made into a laminar flow and noise generation can be prevented. It can be prevented.

(Effects of the invention) As described above, according to the invention, abnormal noise generated when pressure oil passes through a fixed throttle can be suppressed by the simple means of providing a rectifying member downstream of the fixed throttle. This can be reliably prevented, and has the effect of reducing unpleasant and harsh fluid noise that accompanies driving.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram of the first embodiment of the present invention;
FIG. 3 is an enlarged view of the main part, FIG. 3 is an enlarged view of the main part of the second embodiment, FIG. 4 is an explanatory diagram showing the steering torque and output characteristics, and FIG. 5 is a sectional view of the conventional device. 20...Control valve, 30...Valve spool, 40...Communication path, 43...Fixed orifice (fixed throttle), 50, 50A, 50B...Reaction force chamber,
60, 65... Rectifier collar (rectifier member), 62,
64, 67, 69...hole, 70...electromagnetic solenoid, 72...automatic variable orifice (variable aperture),
80...Pump, 82...Oil tank, 84...
... Controller (control mechanism), 88 ... Vehicle speed sensor.

Claims (1)

[Scope of utility model registration request] A reaction chamber is formed at both ends of the valve spool of the control valve, and a passage is provided in the reaction chamber to guide high pressure from the hydraulic source via a fixed throttle, and a passage is provided to release pressure oil from the reaction chamber to the tank side. The automatic variable throttle is equipped with a control mechanism that increases or decreases the opening of this automatic variable throttle depending on the vehicle speed, and the power is designed to reduce the opening of the automatic variable throttle and increase hydraulic reaction force as the vehicle speed increases. In the steering reaction force adjustment device, a passage for guiding high pressure to the reaction force chamber is formed in the valve housing, this passage is communicated with the pump port via the fixed throttle, and a noise-reducing rectifying member is provided in the fixed throttle. A steering reaction force adjustment device for power steering characterized by an interposed device.