JPS603424Y2 - servo valve - Google Patents

Description

[Detailed explanation of the idea] The present invention relates to a servo valve.

More specifically, it is a servo valve that converts electrical signals into fluid pressure, converts rotational input from a servo motor into linear displacement of the valve body, and changes the opening area with the valve seat to respond to the input. This invention relates to a servo valve that obtains a fluid pressure output.

A valve that uses a nozzle-flapper mechanism is known as a valve that converts displacement into fluid pressure.

This is a device in which a nozzle and a flapper are disposed facing each other, a minute displacement of the flapper is used as an input, and a change in back pressure of the nozzle is outputted, and is widely used in pneumatic instruments and the like.

However, in general, in a device using this type of nozzle flapper mechanism, the output can be less than the pressure O, as shown by the dotted line A in FIG. 1, and the non-linear error is large near the pressure 0.

Additionally, the rate of change in output pressure, that is, the gain, with respect to a change in the gap between the nozzle and the flapper is generally large; for example, when the change in gap is 0.02m+y+, the output air pressure is 0.2m+y+.
kg/CFI! From 1. It changes to Oko/-.

If one with a small gain is made, the output air pressure will not reach O and will be saturated, as shown in Fig. 1B and C.

Therefore, the output air pressure ranges from 0 to, for example, 1. Oko
It is not possible to obtain a system in which a large amount of displacement can be obtained with respect to a change in /Clft, a non-linear error is small near the pressure 0, and the output pressure O can be concentrated.

Further, it is desirable that the linearity error in the displacement change of the valve body with respect to the valve seat (in this case, the displacement change of the flapper with respect to the nozzle) is small.

The purpose of this invention is to reduce the non-linearity error of the output fluid pressure with respect to the input electric signal, to be able to easily change the gain, to be stable, and to have a simple structure, so that the valve body can be moved in the axial direction of the valve seat. The purpose of the present invention is to provide a servo valve that can reliably achieve linear displacement.

In order to distantly relate to this object, the present application provides a valve seat comprising a guide portion having an axial groove on its inner diameter surface, a tapered portion, a straight pipe portion, and a diverging portion whose enlarged end side is closed; An input pipe provided on the valve seat on the enlarged end side of the diverging portion and into which supply fluid pressure is input; and an output pipe provided in a direction substantially perpendicular to the axis of the valve seat of the straight pipe portion or the diverging portion from which fluid pressure output is taken out. and a substantially conical valve body which is inserted into the valve seat from the tapered portion side and has a hole in a direction perpendicular to the axis on its circumferential surface, and a groove in the valve seat and a hole in the valve body are connected to each other. A servo valve comprising a locking mechanism consisting of a ball to be stopped and a spring that presses the ball into the groove, and a servo motor part whose output shaft is rotatably screwed into the valve body. death,
Supply fluid pressure from the input pipe, drive the servo motor part using the servo signal, insert the valve body freely toward and away from the valve seat based on the locking mechanism, and output fluid pressure from the output pipe in accordance with the servo signal. It is designed to take out the .

FIG. 2 is an explanatory view of the configuration of an embodiment of the present invention, in which A is a longitudinal cross-sectional view and B is a cross-sectional view taken along line A-A' of A.

In the figure, 1 is a cylindrical valve seat.

Reference numeral 10 denotes a guide portion, in which a groove 101 having a triangular cross section is provided in the axial direction, as shown in Figure B.

11 is a conical tapered portion that tapers toward the left in the figure;
2 is a straight pipe portion, and 13 is a diverging portion that expands into a conical shape as it progresses toward the left in the figure.

Reference numeral 2 designates a lid provided on the open end side of the diverging portion, and 3 designates an input pipe provided on the lid 2 and arranged on the axis of the valve seat 1.

Reference numeral 4 designates an output pipe which is also provided on the lid 2 and arranged perpendicular to the axis of the valve seat 1.

5 is a valve body inserted into the valve seat 1 from the tapered portion 11 side;
It has a conical shape, and the tip part is made at an angle of 6 to 10 degrees in this case so as not to disturb the fluid flow.

51 is a hole provided around the valve body 5 in the radial direction.

6 is a locking mechanism consisting of a ball 61 and a spring 62.

The ball 61 is arranged so as to lock the groove 101 and the hole 51 together, and is pressed against the groove 101 by a spring 62.

Reference numeral 7 denotes a gear mechanism attached to the guide portion 10 side, and its output shaft 71 is rotatably screwed into the valve body 5, and the valve body 5 is configured to be movable in the direction of arrow X.

8 is a servo motor section connected to the gear mechanism 7.

In the above configuration, the supply air pressure Ps introduced from the input pipe 3 is taken out from the output pipe 4 as an output air pressure Po.

As shown in Fig. 1, the output air pressure Po gradually decreases from the supply air pressure Ps as the valve 5 is moved from the close contact state with the valve seat 1 to the right in the figure and the opening area with the valve seat 1 is increased. ,
Eventually, the pressure drops to below atmospheric pressure, and the slope gradually becomes gentler under atmospheric pressure.

Therefore, compared to the characteristic curve of the nozzle flapper mechanism commonly used in the past, which is shown by the dotted line in FIG. becomes less.

Next, now, 1: Effective length of the valve of the present invention, X: Stroke α: 172 of the apex angle of valve 5 d: Inner diameter of valve seat 1 Then, in principle, this device can be expressed as shown in FIG.

Therefore, 1-4@sinα The average circumference Cav is = w (d-x sin α * cos α) The flow area A is A = l @Cav =? rxsinα (d-xsina
α) Rate of change in area with respect to stroke X・C03 If X is small, A = (ydsina) be able to.

In addition, since the valve 5 and the tapered portion 11 are mutually smoothly tapered, the air flow is not disturbed. Therefore, the output pressure Po is stable without noise caused by air turbulence being added to the output pressure Po. is obtained.

In this case, the valve body 5 receives rotational input from the output shaft 71, but the ball 61, which is engaged in the hole 51 of the valve body 5, is simultaneously pressed by the spring 62 so that it is engaged in the groove 101. Therefore, the ball 61 resists this pressing force.
The valve body 5 reliably moves linearly in the axial direction of the valve seat without rotating unless a large rotational force is applied to disengage it from the groove 101.

That is, the rotation of the output shaft 71 causes the valve body 5 to move in the direction of the arrow X.

In this case, since the groove 101 and the ball 61 are in point contact, there is little friction.

Since the ball 61 is pressed against the groove 101 by the spring 62, there is no need to increase the dimensional accuracy of the groove as in the case of a key groove, and manufacturing is easy and inexpensive.

Note that the groove 101 does not have a triangular cross section, but as shown in FIGS. 4A and 4B.
As shown in FIG. 2, the groove may have a U-shaped cross section or a rectangular cross-sectional shape, and in short, any groove that can guide the ball 61 may be used.

FIG. 5 is an explanatory diagram of the configuration of another embodiment of the present invention.

In this embodiment, a spring 9 is provided between the tapered portion 11 and the valve body 5, which presses the valve body 5 against the output shaft 71 to increase friction in the rotational direction and improve the rotation prevention effect. , the backlash between the output shaft 71 and the valve body 5 is eliminated.

In the above-mentioned embodiment, the output pipe 4 was described as being provided in the lid 2, but it goes without saying that it may be provided in the straight pipe portion 12 or the widening portion 13.

As explained above, according to the present invention, it is possible to obtain from supply fluid pressure to negative pressure, the nonlinear error of output fluid pressure with respect to input displacement is small, the gain can be easily changed, and it is stable. With a simple configuration, it is possible to realize a servo valve in which the valve body can reliably perform linear displacement in the axial direction of the valve seat.

[Brief explanation of the drawing]

Fig. 1 is an explanatory diagram of the characteristics of a device using the device of the present invention and a nozzle flapper mechanism, and Fig. 2 is an explanatory diagram of the configuration of an embodiment of the present invention, where A is a longitudinal cross-sectional view and B is a cross-section taken along line A-A' of A. Figures 3 and 3 are diagrams explaining the principle of Figure 2, Figures 4A and B are diagrams illustrating the configuration of main parts of another embodiment of the present invention, and Figure 5 is a diagram illustrating the configuration of another embodiment of the present invention. It is. 1... Valve seat, 10... Guide part, 1
01...Groove, 11...Tapered portion, 12
・・・・・・Straight pipe part, 13 ・・・ Wide end part, 2
...Lid, 3...Input tube, 4...
・Output pipe, 5... Valve body, 51... Hole,
6...Locking mechanism, 61...Ball, 6
2.9... Spring, 7... Gear mechanism, 71... Output shaft, 8... Servo motor section.

Claims (1)

[Scope of utility model registration request] A guide portion having an axial groove on its inner diameter surface, a valve seat consisting of a widened portion with a tapered portion and a straight tube portion closed on the enlarged end side, and a valve seat on the enlarged end side of the widened portion. an input pipe into which supply fluid pressure is input; an output pipe which is provided in a direction substantially perpendicular to the axis of the valve seat of the straight pipe portion or the diverging portion and from which fluid pressure output is taken out; and an output pipe that approaches and separates from the valve seat from the tapered portion side. A substantially conical valve body that is freely inserted and has a hole perpendicular to the axis on its face, a ball that is engaged with the groove of the valve seat and the hole of the valve body, and the ball is pressed into the groove. A servo valve comprising a locking mechanism including a spring, and a servo motor portion whose output shaft is rotatably screwed into the valve body.