JPH0526202A - Nozzle-flapper device - Google Patents

Abstract

PURPOSE:To provide a nozzle-flapper device which has a simple structure and is not bulky in a servo valve which converts an electric signal to a hydraulic pressure by using a nozzle-flapper. CONSTITUTION:A shaft part 3c is provided on one end of a valve spool 3. A nozzle 4a lead to an end oil chamber 1a of the valve spool 3 is provided on an end of a tube 4 screwed with the shaft part 3c. 1 The tube 4 is inserted into a sleeve 6 projected into a case 5 which houses a stepping motor 7. An arm 7b fixed to arm output shaft 7a of the stepping motor 7 is inserted into the sleeve 6 from slits 6a, 6b formed on the sleeve 6. 1 A steel ball 8 is arranged on a portion sandwiched between the tube 4 and the arm 7b, in the sleeve 6. When the arm 7b is rotated by the rotation of the stepping motor 7, the steel ball 8 is pressurized by oil injected from the nozzle 4a or the arm 7b and moved in the sleeve 6. The valve spool 3 is slid following the steel ball 8, and stops when a gap between the end of the tube 4 and the steel ball 8 reaches a proper value.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a nozzle flapper device for a servo valve.

[0002]

2. Description of the Related Art For a servo valve having one nozzle flapper mechanism, as shown in, for example, Japanese Utility Model Laid-Open No. 2-339049, an eccentric cam plate is rotated by using a stepping motor, and the eccentric cam plate is rotated. It is known that a spool of a fluid pressure control valve formed integrally with the nozzle is driven by causing the nozzle close to the nozzle to follow.

[0003]

In the nozzle flapper mechanism using the eccentric cam plate as the flapper, the center line of the nozzle 12 is on the normal line to the eccentric cam plate 11 at the position of θb in FIG. Eccentric cam plate 11
When the rotation center of is set, the eccentric cam plate 1 at θa
The positional relationship between the nozzle 1 and the nozzle 12 is as shown in FIG. 3, and the eccentric cam plate 11 interferes with the nozzle 12 before the clearance c ′ between the tip of the nozzle 12 and the eccentric cam plate 11 reaches an appropriate value c, and the eccentric cam The plate 11 may be stuck. Such a problem can be prevented by increasing the curvature of the eccentric cam plate, but since the size of the eccentric cam plate increases and the moment of inertia also increases, a stepping motor with a large driving torque is required. Further, since the stroke of the valve spool cannot be made larger than the radius of the eccentric cam plate, in order to increase the stroke of the spool, the eccentric cam plate must be further enlarged.

The clearance c between the tip of the nozzle and the eccentric cam plate is a value determined by the diameter of the nozzle and the diameter of the fixed diaphragm 9a. Generally, if c is increased, the responsiveness deteriorates. In a hydraulic control valve that requires a certain degree of responsiveness, c is designed to be around 100 μm.

The present invention focuses on the above-mentioned conventional problems, and the nozzle-flapper is such that the relative relationship between the nozzle and the flapper is always unchanged and the field is small even when the spool stroke of the fluid pressure control valve is large. The purpose is to provide a device.

[0006]

In order to achieve the above object, a nozzle flapper device according to the present invention has a small end side face and a large end side end face of a valve spool which slides in a hole provided in a valve body, respectively. An oil chamber for applying pressure oil is provided, and a pressure oil passage extending from a hydraulic pressure source to an oil chamber provided on the small end side of the valve spool, and a large end side of the valve spool branched from this pressure oil passage through a throttle And a pressure oil passage leading to an oil chamber provided on the valve spool, a shaft portion is provided on the end surface of the valve spool on the large end side, and a nozzle communicating with the oil chamber on the large end side of the valve spool is provided at the tip of the shaft portion. In a servo valve in which the valve spool slides following the displacement of a flapper that is brought close to a nozzle, a case that houses a stepping motor is fixed to the valve body, and a sleeve that projects from the valve body into the case. , A slit provided parallel to the axis of the sleeve, the end of an arm fixed to the output shaft of the stepping motor is slidably inserted into the sleeve through the slit, and the shaft portion provided on the end face of the valve spool on the large end side. Is slidably inserted into the sleeve, and a steel ball that slides in the sleeve is provided between the tip of the shaft and the tip of the arm.

[0007]

According to the above construction, the shaft portion and the steel ball provided on the end face on the large end side of the valve spool are slidably inserted into the sleeves protruding into the stepping motor case, and the output shaft of the stepping motor is attached. Since the fixed arm is inserted into the sleeve through the slit, the rotation of the stepping motor based on the control signal is transmitted to the arm, and when the arm moves in the slit, the steel ball also slides in the sleeve. At this time, the gap between the steel ball and the nozzle provided at the tip of the shaft portion changes, and the hydraulic pressure at both ends of the valve spool can be made higher or lower, so that the valve spool slides following the steel ball. When the rotation of the stepping motor is stopped, the steel ball comes to rest, and when the clearance between the steel ball and the tip of the shaft reaches an appropriate value, sliding of the valve spool also stops.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a nozzle flapper device according to the present invention will be described below with reference to the drawings. Figure 1
It is a partial cross-sectional view of a nozzle flapper device that controls the spool stroke of the control valve provided in the hydraulic circuit. A shaft portion 3 having a screw hole 3a and a passage 3b at the tip of a valve spool 3 slidable in a sleeve 2 fitted in a valve body 1.
c is provided, and a tube 4 having a nozzle 4a at its tip is screwed into the screw hole 3a. A case 5 is fixed to the valve body 1, and the pipe 4 is attached to a sleeve 6 fitted in the case 5.
Is slidably inserted. The sleeve 6 is provided with slits 6a and 6b communicating from the outer circumference to the inner circumference at intervals of 180 ° in the axial direction. The stepping motor 7 is fitted in the hole 5a provided in the case 5, and the arm 7 fixed to the output shaft 7a of the stepping motor 7 is provided.
The tip of b is a slit 6b provided in the sleeve 6.
Is inserted into the sleeve 6. The arm 7b can freely slide in the slits 6b and 6a as the output shaft 7a of the stepping motor 7 rotates. A steel ball 8 slidable in the sleeve 6 is inserted between the tip of the tube 4 and the tip of the arm 7b.

The valve body 1 is provided with an oil chamber 1a at one end of a sleeve 2, and the oil inlet / outlet port 1b communicates with the oil chamber 1a via a throttle 1c. In addition, the hole 3 provided in the shaft portion 3c
the oil chamber 1a, the passage 3b and the nozzle 4a depending on d.
And are in communication. Further, a spring 9 for returning the valve spool 3 to the neutral position is mounted in the oil chamber 1a, and the spring 9 biases the end face of the valve spool 3 to the left side in FIG. There is. On the other hand, the passage 5b communicating with the hole 5a provided in the case 5 communicates with the drain hole 1d provided in the valve body 1. Although not shown, the sleeve 2
An oil chamber and a spring that returns the valve spool to the neutral position are also provided at the other end of the oil chamber, and the oil chamber communicates with the oil chamber 1a via the oil inlet / outlet port 1b.

Next, the operation of the nozzle flapper device in this embodiment will be described. The pressure oil supplied from the oil pressure source enters the oil chamber 1a through the oil inlet / outlet 1b, the throttle 1c, the hole 3d, the passage 3b, and the pipe 4, and is ejected from the nozzle 4a toward the steel ball 8. .. This oil drops into the hole 5a and returns from the drain hole 1d to the oil tank via the passage 5b.

When a drive signal is input to the stepping motor 7 to start rotation, the arm 7b also rotates. Now, when the arm 7b rotates counterclockwise and the steel ball 8 is pushed by the arm 7b and starts sliding to the left in FIG. 1, the gap between the end surface of the pipe 4 and the steel ball 8 becomes smaller than the appropriate value c. So, tube 4,
The pressure in the passage 3b and the oil chamber 1a rises and the valve spool 3
Is pushed to the left. Then, the stepping motor 7 rotates by the command angle and stops, and the steel ball 8 pushed by the arm 7b
When the gap between the end surface of the pipe 4 and the steel ball 8 reaches an appropriate value c, the pressure inside the oil chamber 1a balances with the pressure inside the oil chamber (not shown) at the other end of the sleeve 2, The sliding of the spool 3 stops.

When the arm 7b rotates clockwise, the steel ball 8 is pressed against the arm 7b by the oil ejected from the nozzle 4a, so that the gap between the end surface of the pipe 4 and the steel ball 8 becomes large. As a result, the pressure in the oil chamber 1a decreases and the valve spool 3 is pushed to the right. When the rotation of the stepping motor 7 stops, the sliding of the steel ball 8 stops, and when the clearance c between the steel ball 8 and the end surface of the pipe 4 reaches an appropriate value, the pressure inside the oil chamber 1a and the other end of the sleeve 2 not shown. The pressure in the oil chamber is balanced and the sliding of the valve spool 3 stops.

[0013]

As described above, according to the present invention, the rotation angle of the stepping motor is transmitted to the steel ball sliding in the sleeve through the arm so that the steel ball has a flapper function. As a result, the following effects can be obtained. (1) Since the valve spool shaft portion having the nozzle at the tip and the steel ball facing the nozzle both reciprocate in the sleeve, the center line of the nozzle and the center of the steel ball always coincide with each other and the relative relationship is It is immutable. Therefore, the valve spool slides smoothly, and accurate stroke control becomes possible.
(2) It is possible to easily cope with a valve spool having a large stroke, and even in that case, the nozzle flapper device does not take up space. (3) Since the stepping motor only pushes the steel ball pushed by the oil ejected from the nozzle through the arm, the driving torque may be extremely small. (4) A nozzle / flapper device having a simple structure and high reliability can be obtained.

[Brief description of drawings]

FIG. 1 is a partial cross-sectional view showing an embodiment of a servo valve equipped with a nozzle flapper device according to the present invention.

FIG. 2 is a sectional view showing an example of a servo valve equipped with a nozzle flapper mechanism according to a conventional technique.

FIG. 3 is a partial explanatory view showing a state where the nozzle tip interferes with the eccentric cam plate in the nozzle flapper mechanism of FIG.

[Explanation of symbols]

 1 Valve Main Body 1a Oil Chamber 1c Throttle 2,6 Sleeve 3 Valve Spool 3c Shaft Part 4 Tube 4a, 12 Nozzle 5 Case 6a, 6b Slit 7 Stepping Motor 7a Output Shaft 7b Arm 8 Steel Ball

Claims (1)

Claim: What is claimed is: 1. A valve spool that slides in a hole provided in a valve body is provided with an oil chamber for applying pressure oil to each of a small end side surface and a large end side end surface of the valve spool. A pressure oil passage leading to an oil chamber provided on the small end side of the spool and a pressure oil passage branched from the pressure oil passage leading to the oil chamber provided on the large end side of the valve spool via a throttle are provided. A shaft portion is provided on the large end side end surface of the valve spool, and a nozzle communicating with the large end side oil chamber of the valve spool is provided at the tip of the shaft portion, and the valve spool follows the displacement of the flapper that is brought close to the nozzle. In a servo valve that slides, a case accommodating a stepping motor is fixed to the valve body, and a sleeve protruding from the valve body into the case,
A slit parallel to the axial center of the sleeve is provided, and the tip of an arm fixed to the output shaft of the stepping motor is slidably inserted into the sleeve through the slit, and a shaft portion provided on the end face on the large end side of the valve spool is attached. A nozzle / flapper device, characterized in that a steel ball that slides in the sleeve is slidably fitted and that slides in the sleeve between the tip of the shaft and the tip of the arm.