JPH0460203A - Servo valve - Google Patents

Abstract

PURPOSE:To simplify a structure and obtain a function suitable for fail safe by constructing such that two spools parallelly arranged in a valve body are moved in opposite directions to each other to supply and discharge pressure oil to/from actuators, and moving smoothly one of the spools when sliding failure occurs to the other. CONSTITUTION:Sleeves 12a, 12b in which spools 13a, 13b are slidably inserted respectively, are inserted into a valve body 10. When an output shaft 37 of a motor 40 is rotated counterclockwise, the spools 13a, 13b are slid respectively in left and right directions through respective spherical bearings 39, 39. Pump ports P1, P2 and changeover ports 14, l4', 15, 15' are opened, pressure oil is supplied to circuits 19, 19', and a rod 25 of actuators 23, 24 are interlockingly moved rightward. During operation, in case that failure occurs in the sliding of the spool 13a, a slider 34 on the side of the spool 13a pushes only a spacer 28 leftward for moving it. A spring 29 is pushed by a pin 30 rightward and compressed, to escape the force from the output shaft 37. In this case, the spool 13b is normally moved.

Description

[Detailed description of the invention] [Industrial application field] The present invention applies, for example, to an aircraft control servo system.

[Prior Art] As a servo valve of this type of servo device, for example, the seventh
The one shown in the figure has been developed.

This is composed of a valve body 1, a sleeve 2 provided in the valve body 1, and a spool 3 slidably inserted into the sleeve 2. The valve body 1 and the sleeve 2 are connected to two actuators 4, The spool 3 forms two sets of pump ports (Pi, P2) and two sets of tank ports (R1, R2) leading to the pump ports Pi, P2.
2 and tank ports R1 and R2 to drive the rods 6 of the actuators 4 and 5 to the left or right in the figure.

However, since this servo valve has a single integrated spool 3, debris or other foreign matter may get caught between the sleeve 2 and spool 3, increasing the sliding resistance of the spool 3 or causing malfunction. In this case, the boats cannot be switched and the actuators 4 and 5 will not move.

For this reason, a fail-safe servo valve as shown in FIG. 8, for example, was developed to solve this problem. That is, this servo valve has a fixed sleeve 7a inside the valve body 41a.
A movable sleeve 7bt is provided within this fixed sleeve 7a.
1- The spool 8 is slidably inserted into the movable sleeve 7b, and the spool 8 is slidably inserted into the movable sleeve 7b, and the valve body 1a and the sleeve? Two sets of bomb boats PL installed in a and 7b,
P2 and tank ports R1 and R2 are switched by a spool 8. In this case, if sliding failure occurs for some reason, the movable spool? Slide b and auxiliary boat 9
The actuator 4.5 is driven by supplying and discharging pressure oil from the actuator 4.5.

[Lesson 11 that the invention attempts to solve! ] However, the above-mentioned double sleeve type servo valve has a complicated sleeve structure, and requires two sets of pump bows).
In order to open and close Pi, R2 and tank ports I'll and R2 in conjunction with each other, it is necessary to precisely set the neutral position of the spool 8 and the movable sleeve 7a, which makes hole drilling and assembly difficult and expensive. .

Furthermore, since the sleeves are double-layered, there is a correspondingly large gap, which tends to cause oil leakage, and in order to prevent this, the sealing mechanism needs to be precise and a large number of sealing members are required.

Furthermore, two sets of pump bows) Pi, R2 and tank bows)
Since R1 and R2 are provided in the axial direction along the spool 8, the valve body 1a becomes long, and installation in the axial direction has the disadvantage of being subject to space constraints.

SUMMARY OF THE INVENTION Therefore, the objects of the present invention are to provide a sleeve with a simple structure, easy to set the neutral position of the spool, easy to drill holes and assemble, shorten the axial length, and enable fail-safe use. To provide a servo valve suitable for

[Means for Solving the Problems] In order to achieve the above object, the configuration of the present invention is such that two sleeves are provided in parallel within the valve body, and pressure oil is supplied and discharged from the valve body and sleeve to the two actuators, respectively. Two sets of pump ports and tank ports are provided, a spool for opening and closing the respective pump ports and tank ports is slidably inserted into each sleeve, and a spacer is slidably inserted at one end of each spool. A spring and a slider biased by the spring are inserted into this spacer, and the slider is connected to the rotating shaft of the motor via a drive direction conversion mechanism, so that the rotational movement of the rotating shaft is transferred via the slider. This is characterized in that each spool is converted into linear motion in opposite directions.

[Function] When the rotation shaft of the motor is rotated, the two spools move in opposite directions through the drive direction conversion mechanism, and each spool switches between two sets of pump ports and tank ports, so that the actuator is connected to the actuator from the same direction. Supply and drain pressure oil. If one spool has a sliding failure, compress the spring on the spool side or slide the slider,
The other normal spool should operate smoothly.

[Example] Next, the present invention will be explained in detail.

FIG. 1 shows an embodiment of the invention.

Two sleeves 12a and 12b are incorporated into the valve body 10 via a seal 11, and each sleeve 12a
.

12b respectively contain the first. Second spool 13a.

13b is slidably inserted through lands a, b, c, and d.

Valve body 10 and first sleeve 12a have pump bow) PI and tank bow) R1 and switching boat 14.15 and low pressure bow) 1B, 1? is formed, and the low pressure boat 1
6.17 is connected to the tank bow R1 via the circuit 18, and is also connected to pressure chambers 21, 22 at both ends of the spool 13a.

Similarly, the pump port P2, tank port R2, and switching boat 14' are also connected to the valve body lO and the second sleeve +2b.
, 15" and low pressure boats 1B", 17' are formed, and the tank boat R2 is connected to pressure chambers 21° and 22' at both ends of the second spool 13b via a circuit 18a.

Switching bows) 14.15 are connected to the pressure chamber of the first actuator 23 via circuits I9, 20 and a bypass valve 22, and switching bows) 14', 15° are connected to the second actuator via circuits 19a, 20a. The pressure chamber of the actuator 24 is connected to the pressure chamber of the actuator 24 .

1st. The second actuators 23,24 are linked via a rod 25, but the rod 25 does not have to be common.

A spring 213.26a that biases the spools 13a, 13b to the right is provided in the pressure chamber 21.21' on the tip side of the spools 13a, 13b.
Spool position sensors 27, 27 are provided at the rear end of 3b.

1st. The other ends of the second spools 13a and 13b are connected to the pressure chamber 2.
2, and spacers 2 and 2 are slidably inserted into these positions, respectively.

A spring 28, which is held between a fixed sheet 33 held by a snap ring 3B and a movable sheet 32, is inserted into the outer periphery of the rear end of each spacer 13a, 13b. A slider 34 is slidably inserted into and out of contact with a stopper 35,
This slider 34 is always urged toward the tip side by a spring 29 via the movable seat 32.

A hole 31 is formed in the spacer 28 in the radial direction, and a pin 30 that contacts the movable sheet 32 is inserted into the hole 31. The inner diameter of the hole 31 is considerably larger than the outer diameter of the pin 30, allowing the pin 30 to move.

The slider 34 is movably connected to a motor output shaft 37 which is a rotating shaft of a DC brushless motor or the like via a drive direction conversion mechanism A.

The drive direction conversion mechanism A consists of a hole 38 in the output shaft 37 and a spherical protrusion protruding from the slider 34, that is, a spherical bearing 38, and a spherical bearing 35 extending laterally from the slider 34 of each spool to the output shaft 37 extending in the vertical direction. are fitted together so that they can move freely.

The motor 40 includes a stator 41, a sleeve 42, and a rotor 43.
and an output shaft 37, and when the output shaft 37 rotates, for example, the first spool 13a is pushed by the spherical shaft 35 and moves to the left in the figure, and conversely, the second spool 13b moves to the right. do.

In the neutral position, the spools 13a and 13b are positioned as shown in FIGS. 1 and 3. In this state, when the output shaft 37 of the motor 40 is rotated counterclockwise in FIG.
a is pushed to the left and the second spool 13b is pushed to the right and slides in the same direction. In this case, the friction of the slider 34 with respect to the spacer 2 is balanced with the repulsive force of the spring 28, and the slider 34 is attached to the spool 13a.
, move together with 13b.

When the spools 13a and 13b move, each pump port P
I, P2 and switching boats 14, 14', 15, 15°
is opened, pressure oil is supplied to circuits 19 and 19', and circuit 2
0.20' of pressure oil is discharged and each actuator 23
．． 24 rods 25 move in conjunction with each other to the right in the figure.

During operation, for example, the first spool 13a may
For example, assume that a foreign object enters between the sleeve 12a and a sliding failure occurs, resulting in a fail-safe state. In this case, even if the output shaft 37 rotates counterclockwise, the first
At this time, the slider 34 on the first spool 13a side moves only the spacer 28 by pushing it to the left via the stopper 35, as shown in FIG. The second spool 13b is pushed in the direction and compressed, releasing the force from the output shaft 37. At this time, the second spool 13b moves normally.

When the output shaft 37 is further rotated clockwise in the same state, the slider 34 compresses the spring via the movable seat 32 and moves to the right, as shown in FIG. Release pressure.

FIG. 6 relates to another embodiment of the present invention, in which the motor 40
In this example, the output shaft 37a is connected to the first and second spools 13a,
13b are connected. 1st. ! $2 spool 13
Spherical bearings 44.a and 13b are inserted alternately.
44 is provided, and this spherical bearing 44.44 is connected to the output shaft 37.
a, and the first and second spools 13a and 13b move in opposite directions while the output shaft 37a rotates.

The rest of the structure is the same as the embodiment shown in FIG. 1, and the same reference numerals are used to omit the details.

[Effect of the invention] According to the present invention, there are the following effects.

■Since the sleeves are provided in parallel and only one is provided for each spool, the axial length can be shortened and the sleeve can be easily processed.

The structure is simple.

(2) Since each spool is connected to the rotating shaft of the motor via a drive direction conversion mechanism, S can be achieved by moving the two spools in opposite directions with one motor.

■Even if one spool causes a sliding failure, the slider can move, so the movement of the slider is released, the output shaft is not subjected to excessive load, and the other spools are driven normally.

[Brief explanation of drawings]

FIG. 1 is a vertical sectional front view of a servo valve according to an embodiment of the present invention, FIG. 2 is a sectional view taken along line A-A in FIG. 1, FIG.
Figure 5 is an enlarged sectional view showing the movement of the slider, Figure 6 is an enlarged sectional view showing the movement of the slider.
The figure is a sectional view of a servo valve according to another embodiment, FIG.
FIG. 8 is a sectional view of a conventional servo valve. [Explanation of symbols] 10... Helving body 12a, 12b - Sleeve 13a, 13b... Spool 23.24... Actuator 2B... Spacer 29... Spring 34... Slider 40.40°. ...Motor Al, ^゛...Drive direction conversion mechanism Pl, P2...Pump ports R1, R2...Tank port

Claims (1)

[Claims] Two sleeves are provided in parallel within the valve body, and the valve body and sleeve are provided with two sets of pump ports and tank ports for supplying and discharging pressure oil to the two actuators, respectively, and each of the above pump ports is provided within each sleeve. A spool for opening and closing the tank port and the tank port is slidably inserted, a spacer is slidably inserted into one end of each spool, and a spring and a slider biased by the spring are inserted into the spacer. , a servo valve characterized in that the slider is connected to the rotating shaft of the motor via a drive direction conversion mechanism, and the rotational motion of the rotating shaft is converted to linear motion in mutually opposite directions to each spool via the slider.