JPH01224582A - Variable electromagnetic throttle valve - Google Patents

Abstract

PURPOSE:To prevent change of flow characteristics when fluid force is applied by a hollow spool by letting the fluid force offset if it is produced in any direction of actuating fluid. CONSTITUTION:When flow is produced from an inflow/outflow port A to an inflow/outflow port B, for example, its actuating fluid flows from the inflow/ outflow port A through a spring chamber 20 and a circular groove 27 to the inflow/outflow port B. At this time, fluid force acts to a hollow spool 18 to move it left. Part of the actuating fluid bypassed from the spring chamber 20 through a changeable throttle part (b) is introduced to a pressure chamber R. The pressure in the spring chamber 20 becomes higher than the pressure in the pressure chamber R, and a differential pressure thrust is produced by this pressure difference at the hollow spool 10 to move it left.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a variable electromagnetic throttle valve that is most suitable for use in, for example, a four-wheel steering system.

(Prior Art) The devices shown in FIGS. 3 and 4 have been known for use in four-wheel steering devices.

In this conventional device, an input shaft 2 provided on a handle 1 shown in FIG. 4 is linked to a control valve 3.

A pinion 4 provided at the tip of the input shaft 2 is engaged with a rack 7 formed on a side rod 6 of the front wheel 5.

This side rod 6 transmits the driving force of the power cylinder St to the front wheels 5, and power assists the steering force to the front wheels 5.

Further, the power cylinder S2 for steering the rear wheels 10 is communicated with the control valve 3 via the electromagnetic directional control valve 11 and passages 12 and 13. And said passage 12.1
3 is provided with a fixed throttle 14.15, and a passage 12.13 on the downstream side of the fixed throttle 14.15 is connected via a variable electromagnetic throttle valve Sv. The excitation current for the electromagnetic directional control valve 11 and the variable electromagnetic throttle valve SV is supplied to the vehicle speed sensor.

It is controlled by a controller CO to which a steering angle sensor, pump rotation speed sensor, etc. are connected.

Therefore, the electromagnetic directional control valve 11 is controlled by the controller CO.
The switching direction is controlled according to the excitation current controlled by the electromagnetic directional switching valve 11, and according to the switching direction of the electromagnetic directional switching valve 11, pressure oil flows into the power cylinder S2 and drives the power cylinder S2. The driving force of this power cylinder S2 is transmitted to the rear wheel 10, and the rear wheel 10 is steered.

Further, the opening degree of the variable electromagnetic throttle valve SV is also controlled in accordance with the excitation current controlled in the same manner as described above. Then, depending on the opening degree of the controlled variable electromagnetic throttle valve Sv, the electromagnetic directional control valve 11
The flow rate of working fluid supplied to the pump is controlled.

The specific configuration of the variable electromagnetic throttle valve SV is as shown in FIG. 3.

That is, a pair of inflow and outflow ports A and B are formed in the valve body C, and annular grooves 16.17 are respectively formed inside the inflow and outflow ports A and H, and these annular grooves 16.17 are connected to the inflow and outflow ports. ) are connected to A and B respectively.

A spool 18 is installed inside the valve body C, and one side of the spool 18 is brought into contact with a push rod 19 of a solenoid SO. Further, a plug 24 is attached to one side of the valve body C, which is opposite to the solenoid SO.

Then, the tip of the plug 24 is made to correspond to the spool 18,
A spring chamber 20 is formed between the plug 24 and the spool 18. Further, a spring 2 is installed inside the spring chamber 20, and the spring force of the spring 21 is applied to the end surface of the spool 18.

A communication hole 22 is formed in the spool 18 along its axial center line, and a plurality of communication holes 23 are formed on one side of the communication hole 22. Together with 16, it constitutes a variable aperture a. Further, a notch portion 23a is integrally formed at the tip of the through hole 23, and the notch portion 23a of the through hole 23 is designed to improve the inching characteristics of the spool 18 when the amount of movement of the spool 18 is small. It is for the purpose of

Note that when the spool 18 is in the normal position due to the action of the spring 21, the through hole 23 is closed to the annular groove 18 of the valve body C.

The plug 24 also has a communication hole 25 along its axial center line.
The negative side thereof communicates with the communication hole 22 of the spool 18 via the spring chamber 2o. And plug 2
An annular @ 27 is formed on the outer periphery of the valve body C at a position corresponding to the annular groove 17 of the valve body C, and a plurality of communicating boats 2B are formed at the bottom of the annular groove 27, and this communicating boat 26 is connected to the communicating hole 2B. It opens at 25.

Therefore, the inflow/outflow port B is the annular groove 17 → the annular groove 27 → the communication port 28 → the communication hole 25 → the spring chamber 20.
→It is always in communication with the through hole 23 via the communicating hole 22.

When the solenoid SO is excited and the push rod 13 pushes the spool 18, the spool 18 is switched to the illustrated position in response to the suppressing force of the push rod 18.

When the spool 18 is switched to the illustrated position, the communication hole 22
communicates with the inflow/outflow port A via the variable throttle a. Therefore, the inflow and outflow port A is variable aperture a → communication hole 22 →
It communicates with the inflow/outflow port B via the spring chamber 20 → communication hole 25 → communication boat 28 → annular groove 27 → annular groove 17.

As described above, when the inflow/outflow port A and the inflow/outflow port B communicate with each other, the working fluid flows from the inflow/outflow port A to the inflow/outflow port B, or from the inflow/outflow port 1-B depending on the switching direction of the control valve 3. to the inlet/outlet port A in either direction.

For example, when a flow is generated from the inflow/outflow port A to the outflow/inflow port B, a fluid force acts on the spool 18 to move it to the left in FIG. 3. As a result, the opening degree of the variable aperture a becomes larger than that controlled by the excitation current, and when a flow occurs from the inflow/outflow port A to the outflow/inflow port A, the spool 18 is moved to the right in the drawing. There is a fluid force that tries to make it move. Therefore, the opening degree of the variable aperture a becomes smaller than that controlled by the excitation current.

In this way, since the fluid force acts on the spool 1st, the flow can be changed depending on the direction of the flow, such as from the inflow/outflow port A to the outflow/inflow port B, or from the outflow/inflow port E to the outflow/inflow port A. The opening degree of the aperture section changes.

Therefore, the flow rate characteristics of the working fluid change depending on the direction of the flow.

If the flow rate characteristics of the working fluid change depending on the direction of flow as described above, the steering characteristics will change depending on the direction of rotation of the steering wheel.

The steering sensation differs depending on the steering direction. However, in a four-wheel steering system, it would be dangerous if the steering sensation differed depending on the direction of rotation of the steering wheel, so this conventional electromagnetic valve could not be used in the four-wheel steering system.

(Problems to be Solved by the Present Invention) In the conventional device as described above, the opening degree of the variable throttle a changes depending on the flow direction of the working fluid due to the fluid force acting on the spool 18. The flow characteristics of the working fluid are
There was a problem in that the flow changed depending on the direction of the flow.

An object of the present invention is to provide a variable electromagnetic throttle valve in which the flow rate characteristics of the working fluid do not change even if a fluid force acts on the spool.

(Means for Solving the Problems) This invention provides a valve body having a pair of inflow and outflow ports.
A spool with a through hole on the outer periphery is installed inside, and a solenoid push rod is brought into contact with one end of this spool.
While a spring is applied to the other end, in the axial direction of this spool, the - end side communicates with the above-mentioned through hole, and the other end side has a communication hole that communicates with the other inflow and outflow port through a constriction part. At the same time, the through hole and the spool side opening of one of the inflow and outflow ports together constitute a variable throttle, and further, the other end of the communication hole communicates with the other outflow and inflow port through the throttle part. In the variable 1rLrji throttle valve, a passage connecting the throttle portion and the other inflow/outflow port communicates with a pressure chamber facing one end of the spool.

(Operation of the present invention) Since the present invention is configured as described above, the fluid pressure in the passage connecting the constriction portion and the other inflow/outflow port acts on one end of the spool. Therefore, a pressure difference between the fluid pressure on the upstream side and the fluid pressure on the downstream side of the constriction portion acts on the spool depending on the flow direction of the working fluid in the inflow and outflow ports. This pressure difference acting on the spool cancels out the fluid force acting on the spool.

(Effects of the Present Invention) According to the control device of the present invention, even if a fluid force acts on the spool, the fluid force is canceled out depending on the flow direction of the working fluid. Characteristics do not change.

Therefore, even if this variable electromagnetic throttle valve is used in, for example, a four-wheel steering system, the steering sensation will not vary depending on the direction of rotation of the steering wheel.

(Embodiment of the present invention) In the first embodiment shown in FIG. An annular passage 29 is formed therein.

A variable throttle part is formed between the inner end of the plug 24 and the corresponding spool 18, and the variable throttle part changes depending on the amount of movement of the spool 18, which is moved by the excitation force of the solenoid SO. , the aperture amount is changed.

Note that the variable aperture part constitutes the aperture part of the present invention.

Further, a communication passage 31 is formed on one side of the valve body C, and a communication passage 30 is formed at one end of the communication passage 31, and the other end of the communication passage 30 is opened to the annular passage 29. Furthermore, the communication path 31
A communication passage 32 is formed on the other side, and the other end of the communication passage 32 is opened to the pressure chamber H. The pressure chamber R faces the end of the spool 18 on the opposite side from the spring chamber 20.

In this way, the pressure chamber R is connected to the communication path 32 → the communication path 31 →
Communication path 30 → communicates with the variable throttle part, and further.

Spring chamber 20 → communication hole 2 through this variable throttle part
5 → communication port 26 → annular groove 27 → annular groove 17 → inflow/outflow port) B.

In addition, the pressure chamber R is connected to the communication path 32 → communication path 31 → communication path 30
→ via the annular passage 29 → annular groove 27 → annular groove 17.

It also communicates with the inflow/outflow port B.-6 In other words, the flow path connecting the inflow/outflow port B and the variable throttle part
0→Communication path 31→Communication path 32 communicates with the pressure chamber R facing one end of the spool 18.

Since the configuration other than the above is the same as that of the prior art, the description of the prior art will be used as is for the same components.

When the solenoid SO is excited and the push rod 19 pushes the spool 18, the spool 18 is switched to the illustrated position in response to the pushing force of the push rod 19.

When the spool 18 is switched to the illustrated position, its through hole 2
3 opens into the annular groove 16, and the through hole 23 communicates with the inflow/outflow boat A via the annular groove 1B. Moreover, this inflow/outflow boat A is connected to the communication hole 22→spring chamber 20→communication hole 25→
It communicates with the outflow/inflow boat B via the communication port 26 → annular groove 27 → annular groove 17.

Note that the annular groove 16 constitutes the spool side opening of the present invention.

As mentioned above, when the inflow/outflow boat A and the inflow/outflow port B communicate with each other, the working fluid flows from the inflow/outflow port A to the outflow/inflow boat B or from the outflow/inflow boat B depending on the switching direction of the control valve 3. Flows in either direction to inlet/outlet port A.

Now, for example, when a flow occurs from the inflow/outflow port A to the inflow/outflow port B, the working fluid flows through the inflow/outflow port A.
+ Annular groove 16 → Through hole 23 → Communication hole 22 → Spring chamber 2
0 → communication boat 26 → annular groove 27 → it flows to the inflow/outflow port B via the annular groove 17. At this time, fluid force acts to move the spool 18 to the left in the figure. Further, a part of the working fluid separated from the spring chamber 20 via the constriction part flows into the pressure chamber R via the constriction part 30 → communication passage 31 → communication passage 32. do.

Therefore, in this case, the pressure in the spring chamber 20 on the upstream side of the variable throttle part S becomes higher than the pressure in the pressure chamber H to which the pressure downstream of the variable throttle part S is introduced. That is, on the 1st day of the spool, the above-mentioned pressure difference acts on the spool to move it to the right in the figure.

Therefore, the fluid force that tends to move the spool to the left in the figure is canceled out by the above pressure difference, and the opening degree of the variable throttle part is maintained at the desired opening degree.

In addition, when a flow occurs from the inflow/outflow port A to the outflow/inflow port A, the flow of the working fluid takes the opposite path from the flow from the outflow/inflow port A to the outflow/inflow port B, At this time, fluid force acts on the spool 18 to move it to the right in the figure. Further, the working fluid flowing in from the inflow/outflow port B is transferred from the annular groove 27 to the annular passage 29 or from the annular groove 27 to the communication port 26 to the communication hole 2.
5 → Spring chamber 20 → Communication path 3 via variable throttle part
It flows into the pressure chamber R via 0→communication path 31→communication path 32.

Therefore, in this case, the pressure in the pressure chamber R to which the pressure on the upstream side of the variable throttle part S is guided is higher than the pressure in the spring chamber 20 downstream of the variable throttle part S. That is, on the 1st day of the spool, the above-mentioned pressure difference acts on the spool to move it to the left in the figure.

Therefore, the fluid force that tries to move the spool 18 to the right in the figure is canceled out by the above pressure difference, and the outflow/inflow bow)A
As in the case of the flow from to the inflow/outflow boat B, the opening degree of the variable throttle part is maintained at the desired opening degree.

In this way, regardless of the direction of flow between the pair of inflow and outflow boats A and B, the fluid force acting on the spool 18 is canceled out, and the opening of the variable throttle portion is maintained at the desired opening. Therefore, the flow rate characteristics of the fluid do not change depending on the flow direction of the working fluid. Therefore, if this variable electromagnetic throttle valve is used in a four-wheel steering system, a steering feeling corresponding to the direction of rotation of the steering wheel can be obtained.

In the second embodiment shown in FIG. 2, the communication passage 30 in the first embodiment is formed at the bottom of the annular groove 17 of the valve body C, and the other end of the communication passage 30 communicates with the communication passage 31.

However, the pressure chamber R facing one end of the spool 18 communicates with the inflow/outflow port B via the communication path 32 → communication path 31 → communication path 30 → annular groove 17.

Since the configuration and operation other than those described above are the same as those of the first embodiment, the explanation of the first embodiment will be used as is for the same configuration and operation.

For example, when a flow occurs from the inflow/outflow port A to the inflow/outflow port B, the working fluid flows in the same manner as in the first embodiment, but the working fluid flowing toward the pressure chamber R flows from the spring chamber 20. It flows in through the next channel.

That is, spring chamber 20 → communication hole 25 → communication port 26 → annular groove 27 → annular groove 17 → communication path 30 → communication path 3
1 → Communication passage 32 or spring chamber 20 → Throttle part b →
Annular passage 28 → wall groove 27 → annular groove 17 → communicating passage 30 →
It flows into the pressure chamber H via the communication path 31 → communication path 32.

Also, when a flow occurs from the inflow/outflow port A to the outflow/inflow port A, the working fluid flows in the same manner as in the first embodiment, but the working fluid flowing toward the pressure chamber R flows through the inflow/outflow port B.
It flows into the pressure chamber R via → annular groove 17 → communication passage 30 → communication passage 31 → communication passage 32.

In this way, the working fluid that has flowed into the pressure chamber R acts on one end of the spool 18, and as in the first embodiment, the difference in pressure acting on both ends of the spool 18 causes the spool 1
8 to cancel out the fluid forces acting on it. Therefore, the first
Similar to the embodiment, regardless of the direction of flow between the pair of inflow and outflow ports A and B, the fluid force acting on the spool 18 is canceled out, and the opening degree of the variable restrictor is adjusted to the desired opening. held at a certain degree.

[Brief explanation of the drawing]

Drawing Section 1.2 shows an embodiment of this invention.
2 is a sectional view of the first embodiment, FIG. 2 is a sectional view of the second embodiment, FIG. 3 is a sectional view of the conventional system, and FIG. 4 is a system diagram showing the state of use. A, B...Inflow/outflow port, C...Valve body, SO...
・Solenoid, R...Pressure chamber, a...Variable throttle, 1
8... Spool, 19... Push rod, 21...
...Spring, 22...Communication hole, 23...Through hole,
17.27... annular groove, 29... annular passage, 30.
31.32...Communication path, 16...Annular groove constituting the spool side opening of the present invention, b...Variable throttle part constituting the constriction part of the present invention.

Claims (1)

[Claims] A spool with a through hole on the outer periphery is installed in the valve body, which has a pair of inflow and outflow ports, and a solenoid push rod is brought into contact with one end of the spool, while a spring is applied to the other end. In the axial direction of this spool, a communication hole is formed in which one end side communicates with the above-mentioned through hole, and the other end side communicates with the other outflow/inflow port through a constriction part. In a variable electromagnetic throttle valve, the other end of the communication hole communicates with the other outflow/inflow port via the throttle part, and the other end of the communication hole is connected to the spool side opening of the inlet port to form a variable throttle. A variable electromagnetic throttle valve that communicates the passage connecting the inflow and outflow ports with the pressure chamber facing one end of the spool.