JPS6275111A - Servo valve - Google Patents

Abstract

PURPOSE:To prevent the lead of fluid from a fixed nozzle effectively on a neutral stationary condition, by forming elastic reed pieces on a nozzle flapper. CONSTITUTION:A nozzle flapper 12 is provided with a pair of elastic reed pieces 24a, 24b which are formed oppositely to respective fixed nozzles 16a, 16b, carry out the opening and the closing of the nozzles, and control both the fixed nozzles 16a, 16b to be closed with a prescribed force on a neutral stationary condition. Thereby, the fixed nozzles 16a, 16b can be controlled satisfactorily to be closed by the pair of elastic reed pieces 24a, 24b on the neutral stationary condition, so that lead from the fixed nozzles 16a, 16b can be prevented effectively.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to improvements in servo valves, particularly servo valves used in servo control systems.

[Prior Art] A servo valve arbitrarily adjusts the valve opening degree based on a feedback signal from the driven mechanism within a servo loop for driving or positioning control of a controlled part using air pressure or oil pressure. It has been widely used as a control valve for various machine tools and other industrial machines, and especially in recent years, for robots used for various purposes.

This type of servo valve has various structures and is used depending on the purpose of use, but a typical mechanism of these servo valves is one that controls supply pressure to an actuator with a piston-cylinder mechanism. Mechanisms having a pair of nozzles for control and controlling the supply or discharge of the pressurized fluid from these nozzles are well known.

Generally, such a servo valve controls a nozzle flapper to swing clockwise or counterclockwise using a torque motor, and selectively opens and closes a pair of fixed nozzles that are arranged opposite to each other with the nozzle flapper in between.

[Problems to be Solved by the Invention] In the conventional servo valve mechanism described above, a nozzle flapper is swingably provided between a pair of fixed nozzles, and when the nozzle flapper is moved to one fixed nozzle side, the contact side A nozzle opening/closing action is performed to close one fixed nozzle and open the other fixed nozzle, thereby supplying or discharging pressurized fluid to the actuator.

However, in this conventional device, in a neutral state where no control signal is applied, the nozzle flapper stands still at the center position between both fixed nozzles with a small gap between the two fixed nozzles. It exhibits a slightly released state to ensure the swing stroke of .

For this reason, conventional servo valves have the problem of pressurized fluid leaking from each fixed nozzle in such a neutral stationary state, especially when used in hydraulic equipment where the amount of oil supplied is limited. Effective countermeasures were desired.

The present invention was made in view of the above-mentioned conventional problems, and its purpose is to provide a servo valve that can effectively prevent fluid leakage from a fixed nozzle in a neutral stationary state. It is about providing.

[Means for Solving the Problems] The servo valve of the present invention uses a nozzle flapper driven by a torque motor to control opening and closing of a pair of fixed nozzles disposed opposite to each other in a flapper chamber.

The characteristic feature is that the nozzle flapper is provided with a pair of elastic reed pieces that are provided opposite to each nozzle to open and close the nozzles, and to control the closing of both fixed nozzles with a predetermined biasing force in a neutral stationary state. It lies in the fact that it was formed.

[Function] With the above configuration, the servo valve of the present invention can effectively control the closing of both fixed nozzles by the pair of elastic reed pieces in a neutral stationary state where the torque motor is not driven. As a result, in this state, it becomes possible to effectively prevent leakage from the fixed nozzle, which has been a problem in the past.

In addition, in such a servo valve, when controlling the fixed nozzle to close, the nozzle flapper is moved by the torque motor toward the desired fixed nozzle. As a result, the elastic reed piece that was in contact with this one fixed nozzle separates from the fixed nozzle, achieving desired nozzle closing control. At this time, on the other fixed nozzle side, the elastic reed piece that had already closed the fixed nozzle at the neutral position changes its deflection amount as the nozzle flapper moves, but even in this state, the elastic reed piece that had already closed the fixed nozzle is still closed. The movement of the nozzle flapper is absorbed by the deflection of the elastic reed piece.

As described above, the servo valve of the present invention can effectively control the closing of both fixed nozzles arranged opposite each other to prevent leakage in a neutral stationary state where the torque motor is not driven, and also allows the nozzle flapper to be closed by the torque motor. By moving, the refixed nozzle can be selectively opened and closed, similar to a conventional servo valve.

[Example] Next, preferred embodiments of the present invention will be described based on the drawings.

FIG. 1 shows a preferred embodiment of the servo valve according to the present invention, and the servo valve according to the present invention includes a nozzle flapper 12 whose movement is controlled by a torque motor 10. A pair of fixed nozzles 16a and 16b, which are arranged opposite to each other in the moving direction with the nozzle flapper 12 therebetween, are controlled to open and close.

The upper part of the nozzle flapper 12 is fixed to the flexible tube 18 and supported for frictionless driving movement. The drive axis line is located approximately at the center P of this flexible tube 18, and this P
The nozzle flapper 12 can swing clockwise or counterclockwise around the position.

The flexible tube 18 has a thick upper end, and a lower end of the flexible tube 18 has an annular seven-flange shape. The installation is fixed.

The torque motor 10 also includes a moving armature 20 that is integrally attached and fixed to the upper end of the nozzle flapper 12, and the nozzle flapper 12 is activated by exciting each excitation winding 22 provided on the stator side. Swing control is performed clockwise or counterclockwise around P.

A characteristic feature of the present invention is that the nozzle flapper 12, which is swing-controlled in this manner, is provided opposite to each of the fixed nozzles 16a and 16b, and opens and closes the nozzles, and applies a predetermined urging force to both fixed nozzles in a neutral and stationary state. Fixed nozzles 16a, 16b
This is because a pair of elastic reed pieces 24a and 24b are formed to control closing.

In the embodiment, the elastic lead pieces 24a and 24b are formed by making the tip of the nozzle flapper 12 plate-shaped and partitioning the upper part of the plate into two plates with a slit 26 of a predetermined width.

The flapper width of the pair of elastic lead pieces 24a and 24b along the nozzle axis direction is set to be somewhat larger than the width between the opposing fixed nozzles 16a and 16b. 12 is in a state where its elastic lead pieces 24a and 24b are press-fitted between the fixed nozzles 12a and 12b with a predetermined biasing force.

Further, in this embodiment, the flapper chamber 14 in which the fixed nozzles 16a and 16b are arranged oppositely is connected to the actuator 32.
A flexible partition plate 30 is provided between the flapper chamber 14 and the flexible pipe 18 to prevent fluid from leaking from the flapper chamber 14. .

The present embodiment has the above configuration, and its operation will be explained next.

In the embodiment, one fixed nozzle 16a of the servo valve is used for supplying pressurized fluid, and the other fixed nozzle 16a is used for supplying pressurized fluid.
The case where b is used for fluid discharge will be explained as an example.

FIG. 2 shows the operating state of the servo valve of this embodiment. (C) shows a state in which only the fixed nozzle 16a is controlled to close, and (C) shows a state in which only the other fixed nozzle 16b is controlled to close.

First, when the torque applied from the torque motor 10 to the nozzle flapper 12 is controlled to O, the flapper 12 moves both fixed nozzles 16 by the urging force of each elastic lead piece 24a and 24b.
a and 16b, and the openings 34a and 'C)' of both fixed nozzles 16a and 16b are in a neutral stationary state.
34bG; t, the closing is controlled satisfactorily without any distortion due to the biasing force of the elastic lead pieces 24a and 24b.

In this manner, in a state where both fixed nozzles 16a and 16b were controlled to close, the state of the fluid leaking from each nozzle 16a and 16b was confirmed by experiment under the following conditions.

First, the nozzle flapper 12 is formed using 5US631 spring steel, and the height of the elastic lead pieces 24a and 24b is set to 8 m.
m, the thickness of the elastic lead side portion of the flapper 12 along the nozzle axis direction is 1.7 mm, and the width of the slit 26 is 0.1 m.
Set to m. Also, the nozzle diameter of each fixed nozzle 16a and 16b, that is, the diameter of the openings 34a and 34b, is set to 0.
．． Set within 2 to 0.4 mm.

When the servo valve of the embodiment and the conventional servo valve were compared under these conditions, it was found that according to the present invention, the amount of fluid leaking from both fixed nozzles 16a and 16b whose closing was controlled was lower than that of the conventional servo valve. It was confirmed that the reduction was reduced to one-tenth or less compared to a servo valve.

Further, when controlling one of the fixed nozzles 12a to close, the torque motor 10 applies a torque directed counterclockwise in the figure to the seven wrapper 12. As a result, the flapper 12
swings counterclockwise in the figure. And Fig. 2(b)
As shown in FIG.
6a to achieve the closing control of the nozzle 16a, and at this time, on the other fixed nozzle 16b side, the elastic reed piece 2 which had already closed the fixed nozzle 16b in the neutral position
4b is deformed by the amount of deflection as the flapper 12 moves, but even in this state, the fixed nozzle 16b is subsequently controlled to close.

Thereby, the pressurized fluid is well supplied from the fixed nozzle 16a to the actuator 32 via the flapper chamber 14.

When the other fixed nozzle 16b is controlled to be closed, the torque motor 10 applies a clockwise torque to the flapper 12, contrary to the above.

From these, as shown in FIG. 2(C), the fixed nozzle 1
6b is controlled to close, and the other fixed nozzles 16a are subsequently controlled to close. Therefore, in this case, the fluid supplied to the actuator 32 is transferred to the flapper chamber 14. It is effectively discharged through the fixed nozzle 16b.

In the servo valve of the embodiment, the closing control of each of the fixed nozzles 16a and 16b can be performed in an analog manner using a mechanical feedback signal from the controlled section; It is also possible to perform PWM closing control of the opening 34 to such an extent that pulsating flow does not occur, and by doing so, more accurate control can be performed than in the case of analog control.

[Effects of the Invention] As explained above, according to the present invention, by forming an elastic reed piece on the nozzle flapper, both fixed nozzles arranged facing each other are normally controlled to close with a predetermined urging force, and the nozzle is removed from the nozzle. It becomes possible to effectively suppress fluid leakage, and by driving the torque motor, it is possible to selectively control closing of each of the fixed nozzles.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram showing a preferred embodiment of the servo valve according to the present invention, and FIG. 2 is an explanatory diagram of the operation of the servo valve shown in the first embodiment. 10... Torque motor 12... Nozzle flapper 14... Flapper chambers 16a, 16b... Fixed nozzles 24a, 24b
... Elastic lead piece 26 ... Slit

Claims (2)

[Claims] (1) In a servo valve that uses a nozzle flapper driven by a torque motor to open and close a pair of fixed nozzles arranged oppositely in a flapper chamber, the nozzle flapper is provided opposite to each fixed nozzle to open and close the nozzles. , and a pair of elastic reed pieces for controlling the closing of both fixed nozzles with a predetermined biasing force in a neutral stationary state. (2) The servo valve according to claim (1), wherein the nozzle flapper is swingably held by a flexible tube.