JPH0245525Y2 - - Google Patents

Description

[Detailed description of the invention] [Industrial application field] The invention can be used when controlling the flow rate or pressure of working fluid supplied to a fluid pressure actuator such as a hydraulic cylinder to a value proportional to an electrical input signal. It relates to servo valves.

[Conventional technology]

Conventional servo valves of this type operate a nozzle flapper or a jet pipe using a torque motor, etc., and use the control pressure that changes as a result of the operation to deflect the valve body to control the flow rate or pressure of hydraulic oil supplied to a hydraulic cylinder, etc. I have to.

[The problem that the idea aims to solve]

However, in such a structure, since the swinging members such as the nozzle flapper and jet pipe must be operated accurately within a minute range, the torque motor etc. for driving the swinging members must be precise and complicated. become. Therefore, there are problems in that the reliability of such drive parts is relatively low and adjustment is extremely difficult.

In addition, as another prior art, as shown in the previously filed Japanese Patent Application No. 58-3638 (Japanese Unexamined Patent Publication No. 59-131006), piezoelectric ceramics are attached to both sides of the nozzle flap. There is also a device in which the control pressure can be controlled by bending the nozzle flapper by deforming the nozzle.

However, since this device houses the piezoelectric ceramic, which requires wiring, together with the nozzle flapper inside the body, assembly is troublesome, and the assembly position must be finely adjusted after assembly. It is also difficult to perform maintenance and inspection and replacement work. Also,
The inside of the body is in a harsh environment where oil can splash, so unless special protection measures are taken,
Problems tend to occur in the durability and reliability of wiring.

The present invention was developed in light of these circumstances, and has a simple structure that can significantly improve reliability.Moreover, it is easy to assemble, fine-tune the assembly position, and perform maintenance and inspection. It is an object of the present invention to provide a servo valve that can be easily replaced for repair, and can also improve the durability and reliability of wiring.

[Means to solve the problem]

In order to achieve this object, the present invention provides a body in which a micro-oscillating member is housed with a flexure tube that protrudes from the body, the tip of which is closed and only the inner surface of the tube communicates with the inside of the body. The micro-oscillating member is supported on the inner surface of the flex tube, and the flex tube is deformed by a piezoelectric ceramic disposed on the outer surface of the flex tube, so that the micro-oscillating member can be oscillated. It is characterized by being configured as follows.

[Effect]

With such a structure, when the piezoelectric ceramic is deformed by varying the voltage applied to the piezoelectric ceramic, the flex tube is deformed accordingly. As a result, the minute rocking member supported by the flake shaft tube swings, and the control pressure for driving the valve body changes in accordance with the amount of rocking displacement of the minute rocking member. Therefore, the control pressure can be controlled by adjusting the voltage applied to the piezoelectric ceramic. Since the piezoelectric ceramic deforms in accordance with the applied voltage, delicate swing control of the minute swinging member is possible simply by adjusting the applied voltage.

Moreover, since the tip of the flex tube is closed and only the inner surface thereof communicates with the inside of the body, the piezoelectric ceramic provided on the outer surface of the flex tube is completely connected to the space inside the body. It can be placed in an isolated space. Therefore, compared to the case where the piezoelectric ceramic is incorporated into the body, it is not only possible to assemble the piezoelectric ceramic and finely adjust the assembly position, etc., but also to make wiring for applying voltage to the piezoelectric ceramic easier. There is no need to place it in a harsh environment where oil is splashed. Therefore, the durability and reliability of the wiring can be improved without requiring any special protection measures for the wiring.

〔Example〕

An embodiment of the present invention will be described below with reference to the drawings.

A servo valve 4 according to the present invention is interposed between the hydraulic power source 1 and the tank 2, and the hydraulic cylinder 3.

The servo valve 4 has a pressure port 5 connected to the hydraulic power source 1, a return port 6 connected to the tank 2, and first and second inflow and outflow ports connected to the hydraulic chambers 7 and 8 of the hydraulic cylinder 3, respectively. It has a body 12 with ports 9 and 10 open, and within this body 12 are provided a supply passage 13 communicating with the pressure port 5 and a discharge space 14 communicating with the return port 6. This supply channel 13 and the discharge space 1
4 can be selectively communicated with the respective inflow and outflow ports 9 and 10 by the operation of a spool 16 serving as a valve body. Note that control chambers 17 and 18 are provided at both ends of the spool 16. and,
These control chambers 17 and 18 are connected to a control pressure introduction path 2 having orifices 19 and 20.
1 and 22, respectively, and are connected to the supply flow path 13. Further, the downstream portions of the control pressure introduction passages 21 and 22 from the orifices 19 and 20 are opened into the discharge space 14 through nozzles 23 and 24. The nozzles 23 and 24 are opposed to each other, and a nozzle flapper 25, which is a minute swinging member, is disposed between the nozzles 23 and 24. The nozzle flapper 25 is a plate-shaped member located close to the nozzles 23 and 24, and is connected to the body 12 through a flexure tube 26.
is swingably supported. The flexure tube 26 is a deformable tubular member, and as shown in the drawing, its tip 26a is closed, and only its inner surface 26b is communicated with the inside of the body 12, and is protruded from the body 12. has been done. The base end of the nozzle flapper 25 is supported at the top of the inner surface 26b of the flexure tube 26. Further, the tip of this nozzle flapper 25 is connected to the spool 16 via a feedback spring 27. Then, the flexure tube 26 is placed outside the body 12, that is, on the outer surface 26c of the flexure tube 26.
A pair of piezoelectric ceramics 28 and 29 arranged on the sides
The nozzle flapper 25 is deformed in the tilting direction to swing the nozzle flapper 25. Specifically, fixed walls 31 and 32 are disposed opposite to each other on both sides of the upper end of the flex tube 26, and the piezoelectric ceramics 28 and 29 are placed between the fixed walls 31 and 32 and the flex tube 26. They are interposed respectively. The piezoelectric ceramics 28 and 29 are, for example, beam-shaped, and have terminals 28a, 28b,
By changing the voltage applied between 29a and 29b, it can be expanded and contracted in the axial direction.

With such a configuration, a part of the high-pressure hydraulic oil A introduced into the supply flow path 13 from the pressure port 5 is guided to the nozzles 23 and 24 through the orifices 19 and 20, and each of these nozzles 2
3 and 24 toward the nozzle flapper 25. In this case, if the voltage applied to both piezoelectric ceramics 28 and 29 is adjusted to a required reference voltage and the nozzle flapper 25 is held at the neutral position shown in the drawing, the back pressures of both nozzles 23 and 24 will be equalized. The control pressures introduced into both control chambers 17 and 18 have the same value. Therefore, the spool 16 is held at the neutral position shown in the drawing, the supply passage 13 and the discharge space 14 are closed, and the hydraulic cylinder 3 is locked. If the voltage applied to one of the piezoelectric ceramics 28, 29 is made higher than the reference voltage by a certain value and the voltage applied to the other is made lower than the reference voltage by a certain value from the state shown in FIG. One of 28 and 29 expands while the other shortens. As a result, the nozzle flapper 25 is tilted by an angle corresponding to the amount of deformation of the piezoelectric ceramics 28, 29, and the facing distances between the nozzle flapper 25 and each of the nozzles 23, 24 become different from each other. Therefore, the back pressure of each nozzle 23, 24 changes, and a difference occurs between the control pressures introduced into each control chamber 17, 18, and the spool 16 moves to the right or left in the figure due to the pressure difference. do. When the spool 16 moves, the amount of movement is reflected by the feedback spring 27.
This feeds back to the tip of the nozzle flapper 25, and a force acts on the nozzle flapper 25 to return it to the neutral position. and,
When the spool 16 is deviated to the required position, the nozzle flapper 25 is returned to the neutral position by the feedback force, and the two control pressures become equal, and the spool 16 stops at that point. Accordingly, one of the first and second inflow and outflow ports 9 and 10 communicates with the supply channel 13 opened by the deflection of the spool 16, and the other is connected to the discharge space 14. . Therefore, hydraulic oil is supplied to one of the hydraulic chambers 7 and 8 of the hydraulic cylinder 3 at a flow rate corresponding to the amount of deviation of the spool 16, and the hydraulic oil is discharged from the other one through the discharge space 14. Returned to tank (2). Therefore, the piston 3a of the hydraulic cylinder 3 operates at a speed corresponding to the amount of deviation of the spool 16, in other words, the amount of change in the voltage applied to the piezoelectric ceramics 28, 29.

In this way, in this embodiment, the nozzle flapper 25
Since the oscillation is performed using the piezoelectric ceramics 28 and 29, the following effects can be obtained.

(a) The displacement of the piezoelectric ceramics 28 and 29 is transferred to the nozzle flapper 25 via the flexible tube 26.
Because it only transmits information to the user, it has a much simpler structure and higher reliability than conventional systems that use torque motors or the like.

(b) Since the piezoelectric ceramics 28 and 29 expand or shorten in accordance with the applied voltage, delicate swing control of the nozzle flapper 25 is possible just by adjusting the applied voltage, which is different from the conventional torque motor type. Adjustment can be made more easily than the conventional one, and the piston 5, which is the actuator, can be driven accurately.

(c) Moreover, the nozzle flapper 25 is supported on the inner surface 26b side of the flex tube 26,
Piezoelectric ceramic 28 disposed on the outer surface 26c side,
Since the nozzle flapper 25 can be indirectly swung by the nozzle flapper 29, the assembly work can be performed more easily than when piezoelectric ceramics 28 and 29 are assembled into the narrow body 12. Even after the piezoelectric ceramics 28 and 29 are assembled in the predetermined positions, the piezoelectric ceramics 28 and 29
Since 8 and 29 are located outside, it is easy to finely adjust their mounting positions. Further, with such a structure, maintenance and inspection of the piezoelectric ceramics 28 and 29 can be performed without disassembling work. Furthermore, piezoelectric ceramic 2
Even if the parts 8 and 29 break down, they can be replaced without extensive work. Moreover, each piezoelectric ceramic 2
Since the wiring connected to terminals 8 and 29 is not exposed to the harsh environment where oil is splashed, the durability and reliability of the wiring can be ensured without taking special measures. be.

(d) Also, in this example, piezoelectric ceramic 2
Since the piezoelectric ceramics 28 and 29 are arranged symmetrically, distortion of the piezoelectric ceramics 28 and 29 due to heat can be corrected, and the nozzle flapper 25 can be prevented from being misaligned.

Note that the present invention is of course not limited to the above embodiments. In other words, piezoelectric ceramic has 2
It is not limited to two symmetrically arranged arrangements; for example, there may be only one, but if two are arranged symmetrically, the piezoelectric ceramic will be distorted by heat, as described above, and the nozzle flapper will be misaligned. Such inconveniences can be prevented.

Further, the minute swinging member is not limited to a nozzle flapper, but may be a jet nozzle or the like.

Various other modifications can be made without departing from the spirit of the present invention.

[Effect of idea]

As explained above, the present invention transmits the displacement of the piezoelectric ceramic to a minute swinging member such as a nozzle flapper or jet nozzle via a flex tube that isolates the inside and outside of the body, and responds to the displacement of the piezoelectric ceramic. Since the micro-oscillating member can be oscillated by the micro-oscillating member, the structure is simple and reliable operation can be ensured, and assembly and fine adjustment can be made simple. It is possible to provide a servo valve that not only simplifies maintenance inspections and troubleshooting, but also ensures high durability and reliability for the wiring connected to the piezoelectric ceramic. .

[Brief explanation of the drawing]

The drawing is a schematic sectional view showing an embodiment of the present invention. 4...Servo valve, 16...Valve body (spool), 25...Minute rocking member (nozzle flapper),
26... Flexible tube, 26a... Tip,
26b...inner surface, 26c...outer surface, 28, 29...
...Piezoelectric ceramic.

Claims (1)

[Scope of utility model registration request] In a servo valve that is capable of changing the control pressure for driving a valve body according to the amount of rocking displacement of a minute swinging member such as a noise flapper or a jet nozzle, a body that houses the minute swinging member therein has a tip end. A flexure tube that is closed and communicates with the inside of the body only on its inner surface is protruded, and the micro-oscillation member is supported on the inner surface of the flexure tube, and is disposed on the outer surface of the flexure tube. A servo valve characterized in that the flex tube is deformed by piezoelectric ceramic to cause the minute swing member to swing.