JP2005233220A - Servo valve - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To maintain desired performance of a sleeve and a casing by simply and surely preventing a relative position gap between the sleeve and casing in spite of their different materials even if their ambient temperature is changed. <P>SOLUTION: Projections 41b extending outward are arranged on an outer periphery of the sleeve 41. The projections 41b are opposite to each other at even intervals by centering a standard position C in a longitudinal direction on the outer periphery of the sleeve 41, and the projections 41b are integrated with the sleeve 41. Pin members 6 as retainers are arranged on the casing 40 so as to make the sleeve 41 retain the standard position C. The pin member 6 has a diameter and length to be inserted into a hole 40b of the casing 40. When the pin members 6 are respectively inserted into the holes 40b, the sleeve 41 is retained on the casing 40 so that the projections 41b are interposed between the pin members 6 along a longitudinal direction. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a servo valve, and particularly to a technique in which a casing having a nozzle flapper and a sleeve for guiding a piston connected to the nozzle flapper are made of different materials.

  In general, various types of servo valves have been proposed for use in fuel control of aircraft jet engines. For example, nozzle flapper type servo valves are known.

  Conventionally, this kind of nozzle flapper type servo valve has a casing having a nozzle flapper and a sleeve for guiding a piston connected to the nozzle flapper, and gives torque to the flapper located between the nozzles opposed to each other. Thus, a difference is made in the hydraulic pressure of the hydraulic oil guided to both ends of the piston, and the piston is displaced. The flapper is provided with a feedback wire made of an elastic member, and the tip of the feedback wire is coupled to a predetermined position of the piston, so that the displacement of the piston is fed back to the flapper. The sleeve is made of a small coefficient of thermal expansion, such as stainless steel (SUS), carbon steel, etc., in order to reliably transmit the oil pressure to the piston, and the casing is a light metal to minimize the weight of the entire servo valve. For example, it is made of aluminum.

When torque is applied to the flapper of the servo valve having such a configuration, the piston is displaced due to the difference in back pressure between the two nozzles. At that time, the elastic restoring force of the feedback wire is changed according to the displacement of the piston. Thus, the flapper is returned to the original position, the difference between the back pressures of both noises becomes zero, and the piston stops moving. When the movement of the piston stops, the flow rate of the hydraulic oil is determined by the relative position between the piston and the sleeve (see, for example, Patent Document 1).
JP 2001-012410 A

  By the way, in the conventional servo valve, the sleeve and the casing are made of different materials, and each material has a different coefficient of thermal expansion. Therefore, the material expands and contracts with a different coefficient of thermal expansion depending on the temperature change in the use environment. At this time, for example, if the sleeve is fixed to the casing at one end, the sleeve and the casing are displaced relative to each other by expanding and contracting at different thermal expansion rates. That is, the neutral position of the piston deviates from the reference position of the sleeve. Then, an error occurs in the flow rate of the hydraulic oil, and there is a problem that the performance of the servo valve is deteriorated.

  The present invention has been made in consideration of such circumstances, and its purpose is to maintain the relative position between the sleeve and the casing regardless of the difference in material between the sleeve and the casing even if the temperature changes. It is an object of the present invention to provide a servo valve capable of easily and reliably preventing deviation and maintaining desired performance. )

In order to achieve the above object, the present invention proposes the following means.
The invention according to claim 1 includes a casing having a nozzle flapper and a sleeve for guiding a piston connected to the nozzle flapper, and the relative relationship between the piston and the sleeve based on the correspondence between the nozzle flapper and the piston. In the servo valve that determines the flow rate of hydraulic oil according to the position, the sleeve is provided with a protrusion at a reference position corresponding to the neutral position of the piston, and the protrusion is sandwiched in the longitudinal direction of the sleeve in the casing. A holding body is provided to hold the.
According to a second aspect of the present invention, in the servo valve according to the first aspect, the protrusions are arranged to face each other with a gap in the longitudinal direction of the sleeve around the reference position of the sleeve, or the reference position of the sleeve. And a desired length in the longitudinal direction.
According to a third aspect of the present invention, in the servo valve according to the first or second aspect, the holding body is two pin members that are inserted into a casing and sandwich the protrusion in the longitudinal direction of the sleeve. .
According to a fourth aspect of the present invention, in the servo valve according to the third aspect, when one of the two pin members rotates, the protrusion cooperates with the other pin member. It is characterized by having a shape that sandwiches.
According to a fifth aspect of the present invention, in the servo valve according to the fourth aspect, any one of the pin members is a round bar having a smooth portion on the outer periphery or an elongated oval shape.
The invention according to claim 6 is the servo valve according to claim 3, wherein one of the two pin members is a spring pin.
According to a seventh aspect of the present invention, in the servo valve according to the first aspect, the holding body is a pair of clamping arms that project from the casing toward the projection and sandwich the projection in the longitudinal direction of the sleeve. It is characterized by.

  According to the first aspect of the present invention, the sleeve is held by the casing at the reference position corresponding to the neutral position of the piston when no load is applied to the nozzle flapper mechanism, and the holding body has a protrusion provided on the sleeve in the longitudinal direction. Since the sleeve and casing expand and contract at different thermal expansion rates due to temperature changes in the operating environment, there is no deviation between the neutral position of the piston and the reference position of the sleeve. Due to this, even if the temperature changes, the relative performance between the sleeve and the casing can be easily and reliably prevented and the desired performance can be maintained without regard to the difference in material between the sleeve and the casing. Is obtained.

  According to the second aspect of the present invention, when the holding member sandwiches the protrusions that are arranged to face each other with a gap in the longitudinal direction of the sleeve, an elastic restoring force is inevitably generated on the protrusions, so that the temperature changes. In some cases, the sleeve can be held at the reference position with respect to the casing regardless of the expansion and contraction due to the difference in material, and the sleeve can be satisfactorily held in the casing.

  According to the third aspect of the present invention, since the projection is simply sandwiched between the two pin members, an effect that can be configured easily and reliably without being concerned with expansion and contraction is obtained.

  According to the fourth aspect of the present invention, when one of the two pin members rotates, the projection is sandwiched in cooperation with the other pin member, so that the sleeve is securely held in the casing. Thus, an effect that can be easily and reliably configured regardless of expansion and contraction is obtained.

  According to the invention of claim 5, when the pin member sandwiches the protrusion, when the pin member having the smooth portion or the elliptical pin member is rotated, the pin member having the smooth portion or the elliptical pin member is provided. In addition, since the projection can be reliably sandwiched between the other pin members in the longitudinal direction of the sleeve, an effect can be obtained that can be simply or reliably configured regardless of expansion and contraction.

  According to the sixth aspect of the present invention, when the pin member sandwiches the projection, the projection can be reliably sandwiched by the elastic force of the spring pin, so that an effect of simple and reliable configuration can be obtained.

  According to the seventh aspect of the invention, the pair of holding arms projecting from the casing holds the sleeve in the casing by sandwiching the projection of the sleeve, so that the casing holds the sleeve by forming the casing. The effect which can be kept is acquired.

Embodiments of the present invention will be described below with reference to the drawings. 1 to 4 are views showing a servo valve according to a first embodiment of the present invention. FIG. 1 is a sectional view showing the servo valve, and FIG. 2 is an explanatory side view showing a casing and a sleeve of the servo valve. 3 is a schematic front view showing a casing and a sleeve of the servo valve, and FIG. 4 is an enlarged explanatory view corresponding to the arrow A in FIG.
In FIG. 1, the servo valve 1 roughly includes a torque motor unit 2, a hydraulic pressure amplifying unit 3, a valve unit 4, and a feedback unit 5.

  The torque motor unit 2 includes a permanent magnet 21 having a magnetic pole facing the tip, an armature 22 rotatably provided between the magnetic poles of the permanent magnet 21, and a coil 23 wound around the armature 22. It consists of and. The torque motor unit 2 applies a current to the coil 23 to generate a magnetic field between the tip of the armature 22 and the permanent magnet 21, thereby rotating the armature 22, whereby the input current is supplied to the hydraulic amplifying unit 3. Torque is applied to the flapper 31.

  The hydraulic pressure amplifying unit 3 includes a flapper 31 that swings following the rotation of the armature 22, and a nozzle flapper mechanism (also simply referred to as a nozzle flapper) 30 whose hydraulic pressure changes according to the position of the flapper 31. The flapper 31 is integrally connected to the armature 22 of the torque motor unit 2. The nozzle flapper mechanism 30 is composed of a pair of nozzles 32 and 32 provided to face each other with a flapper 31 therebetween, and a gap of, for example, several tens of μ is formed between the tip of each nozzle 32 and the flapper 31. ing. The hydraulic pressure amplifying unit 3 converts the displacement of the armature 22 of the torque motor unit 2 into a hydraulic pressure difference via a flapper 31.

  The nozzle 32 communicates with both end portions of a sleeve 41 of the valve unit 4 described later, and hydraulic oil is guided into the nozzle 32 through an inlet filter 33 and an inlet orifice 34. That is, the back pressure applied by each nozzle 32 is guided to both end portions of the sleeve 41, that is, both end surfaces of the piston 42 through this hydraulic oil.

  The valve unit 4 includes a sleeve 41 that is inscribed in the casing 40 and a piston 42 that is slidably moved in the sleeve 41. The casing 40 is connected to the supply port 43 so as to communicate with the sleeve 41. A return port 44 and a control port 45 are provided. The sleeve 41 is configured such that the back pressure of both nozzles 32, 32 of the hydraulic amplifying unit 3 is guided to both ends thereof, and the piston 42 has a sleeve 41 corresponding to the difference in back pressure between both nozzles 32, 32. It is configured to move in. The valve 4 is configured so that the ports 43, 44, 45 are opened / closed according to the displacement of the piston 42, or the degree of opening / closing of the ports 43, 44, 45 is adjusted. , 45, the flow rate of the hydraulic oil is controlled.

  The sleeve 41 is provided with a circulation hole 41a through which hydraulic oil flows. The hydraulic oil is supplied to each of the supply port 43, the return port 44, and the control port 45 of the casing 40 through the circulation hole 41a. It has come to be guided. A concave portion 42a having a predetermined depth is formed in an annular shape on the outer peripheral surface of the central portion in the longitudinal direction of the piston 42, and a ball 52 of a feedback wire 51 of the feedback portion 5 described later is slidably coupled in the concave portion 42a. ing.

  The sleeve 41 and the piston 42 are configured to be symmetric with respect to each other, and the sleeve 41 is fixed to the casing 40 at a position where the symmetry plane includes the rotation axis of the armature 22. The position in the sleeve 41 represents a reference position of the sleeve 41 corresponding to a neutral position (described later) of the piston 42 when no load is applied to the nozzle flapper mechanism 30.

  The feedback unit 5 includes an elastically deformable feedback wire 51 whose one end is integrally coupled to the flapper 31 and a ball 52 that is integrally provided at the other end of the feedback wire 51. The piston 42 is slidably coupled to the recess 42 a on the outer peripheral surface of the piston 42. When the feedback wire 51 bends following the displacement of the piston 42, the feedback wire 51 returns from the bent state to the original state, thereby pushing the flapper 31 back to the neutral position and stopping the piston 42 at the position. Determine the flow rate of hydraulic fluid through That is, the feedback wire 51 has a function of feeding back the displacement of the piston 42 to the flapper 31.

Here, the sleeve 41 is made of, for example, stainless steel, and as shown in FIG. 2, a protrusion 41b extending outward is provided on the outer peripheral portion thereof. As shown in FIG. 3, the protrusions 41 b are opposed to each other at an equal interval with a gap around the reference position C in the longitudinal direction on the outer periphery of the sleeve 41, and are provided integrally with the sleeve 41. It has been.
On the other hand, the casing 40 is provided with pin members 6 and 6 (indicated by chain lines in FIG. 2) as holding bodies for holding the sleeve 41 at the reference position C. As shown in FIG. 3, the pin members 6, 6 have a diameter and a length that can be inserted into a hole 40 b provided at an equidistant position around the reference position C in the longitudinal direction in the casing 40. Yes. The hole 40b is provided in the casing 40 so as to correspond to the vicinity of the protrusions 41b and 41b. When the pin member 6 is inserted into the hole 40b of the casing 40, as shown in FIGS. 3 and 4, each pin member 6 extends along the longitudinal direction so that the protrusions 41b and 41b approach each other from the outside. Thus, the sleeve 41 is held at a predetermined position of the casing 40.

  At that time, as shown in FIG. 4, the interval L between the inserted pin member 6 and the pin member 6 is set to be slightly narrower than the dimension L1 between the protrusions 41b and 41b, and the inserted pin member 6 is inserted. Press-fit the protrusions 41b and 41b to be slightly elastically deformed inside, and the elastic restoring force at that time acts on the pin member 6 so that the pin member 6 and the protrusion 41b come into close contact with each other. 41 is prevented from moving.

Next, the operation of the servo valve 1 having the above configuration will be described.
When the input current to the torque motor unit 2 is 0, the flapper 31 is located at an equal distance from both nozzles 32, 32, and the same amount and pressure of hydraulic oil is ejected from both nozzles 32, 32. The back pressure of 32 is in a balanced state. At this time, no load is applied to the nozzle flapper mechanism 30, and the symmetry plane of the piston 42 on which the ball 52 is located is located at a position where the rotation axis of the armature 22 is not included in the symmetry plane, that is, the neutral position. .

  When a current is applied to the torque motor unit 2, torque is generated in the torque motor unit 2 in proportion to the input current, and the armature 22 rotates. When the armature 22 rotates, the flapper 31 of the hydraulic amplifying unit 3 integrally swings and displaces in the direction of the nozzle 32 following the rotation of the armature 22, and is located at an equal distance from the nozzle portions of both nozzles 32 and 32. The distance between the flapper 31 and the two nozzle portions changes. As the distance between the flapper 31 and both nozzle portions changes, a difference occurs in the back pressure of both nozzles 32. By changing the back pressure of both the nozzles 32, 32, a difference occurs in the pressure applied to both end faces of the piston 42, and the piston 42 moves toward a lower pressure.

  When the piston 42 moves, the feedback wire 51 of the feedback unit 5 bends as the piston 42 moves. When the feedback wire 51 is bent, the feedback wire 51 tries to return to the original form, and the flapper 31 is pushed back. Then, the pressure difference applied to both end faces of the piston 42 decreases, and finally the piston 42 stops at that position at a position where the torque applied to the armature 22 and the torque applied to the feedback wire 51 based on the position of the piston 42 are balanced. . In this manner, the flow rate of the hydraulic oil is determined through the flow hole 41a depending on the relative position between the piston 42 and the sleeve 41 in the valve unit 4.

Although the flow rate of the hydraulic oil is determined by the servo valve 1 in this way, when a temperature change occurs due to the environment in which the servo valve 1 is used or the influence of the hydraulic oil, the main components of the servo valve 1 expand due to the temperature change effect. -Since it receives shrinkage, the lengths in the longitudinal direction of the casing 40 and the sleeve 41 change in particular, so that there is a possibility that the relative positions of the sleeve and the casing shift.
However, while the sleeve 41 is provided with the protrusions 41b and 41b facing each other with a gap, the pin member 6 inserted into the hole 40b of the casing 40 presses both the protrusions 41b and 41b inward. Since the sleeve 41 is sandwiched in the longitudinal direction, the sleeve 41 remains held and fixed to the casing 40 at the reference position. That is, even if the length in the longitudinal direction of the sleeve 41 and the casing 40 changes due to expansion / contraction, both 41 and 40 are fixed at the reference position of the sleeve 41, and the relative positional relationship is always at the temperature. It has a certain relationship.

  Further, since the sleeve 41 is fixed to the casing 40 at a reference position corresponding to the neutral position of the piston 42 when no load is applied to the nozzle flapper mechanism 30, the sleeve 41 and the casing 40 are respectively changed by the temperature change of the use environment. Even in the case of expansion / contraction with different thermal expansion coefficients, there is no deviation between the neutral position of the piston 42 and the reference position of the sleeve 41. That is, the correspondence relationship with the torque to be applied to the flapper 31 required for the piston 42 to be positioned at a predetermined position in the sleeve 41 is always kept constant for each temperature.

According to the above configuration, the flow rate of the hydraulic oil determined by the piston 42 being in a predetermined position in the sleeve 41 and the armature 22 necessary for positioning the piston 42 in the predetermined position in the sleeve 41 are applied. Since the correspondence relationship with the power current (torque to be applied to the flapper 31) is kept constant regardless of the temperature, even if a temperature change occurs, the correspondence relationship for each known temperature can be taken into consideration. Performance can be maintained.
Therefore, regardless of the difference in material between the sleeve 41 and the casing 40, even if the temperature changes, the relative position between the sleeve and the casing can be easily shifted without regard to the difference in the material between the two 41, 40. And it can prevent reliably and can maintain desired performance.
In addition, since the error in the flow rate of the hydraulic oil caused by the difference in thermal expansion coefficient between the sleeve 41 and the casing 40 is eliminated, even if the sleeve 41 and the casing 40 are made of different materials, there is no influence. I will not receive it.
Moreover, since the protrusion 41b is pressed and pinched by the pin member 6, the pin member 6 is not likely to drop off. Therefore, the sleeve 41 can be held only by inserting the pin member 6 into the casing 40. It can be done with simple operation.

5 and 6 are views showing the main part of the servo valve according to the second embodiment of the present invention, and correspond to FIGS. 3 and 4, respectively.
5 and 6, in this embodiment, a protrusion 41c having a certain width L2 along the longitudinal direction is formed on the outer periphery of the sleeve 41, and the protrusion 41c is sandwiched between the two pin members 6 and 6A. It has become. The protrusion 41c has a width L2 extending at an equal distance in the length direction around the reference position C at the outer periphery of the sleeve 41. That is, it is the same as that in which the projection 41b in the first embodiment is integrated.

  On the other hand, as shown in FIG. 6, the two pin members 6 and 6A as a holding body are provided. Among them, the pin member 6 is the same as that of the first embodiment described above, and the pin member 6A forms a round bar provided with the smooth portion 7 by cutting off its outer peripheral portion. Then, when the pin members 6 and 6A are respectively inserted from the holes 40b (see FIG. 5) of the casing 40, when the pin member 6A is rotated, the arc portion excluding the smooth portion 7 of the pin 6A and the pin member 6 The sleeve 41 is held by the casing 40 at the reference position C by pressing the protrusion 41c from both sides.

  According to this embodiment, since the sleeve 41 is held by the casing 40 by sandwiching the protrusion between the two pin members 6 and 6A inserted into the casing 40, basically the same effect as the first embodiment. Is obtained. Further, of the two pin members 6 and 6A, one pin member 6A is rotated by the operator, so that the protrusion is pressed between the pin members, but the pin member 6A is released from the operator. Even if it is done, there is no possibility of rotating so as to return to the original state. Therefore, in this respect as well, both pin members are not likely to fall out of the casing 40 as in the second embodiment.

In addition, although the example which provided the smooth part 7 in the outer periphery of a round bar was shown as 6 A of pin members, it is not restricted to this, For example, the cross-sectional view and the elongate pin member which makes an elliptical shape are used, and this pin By inserting and rotating the member into the casing 40, the protrusion 41c can also be sandwiched. Therefore, when one of the pin members rotates, the important point is that the member cooperates with the other pin member. What is necessary is just to make the shape which pinches | interposes protrusion.
In the case of an elliptical shape, the pin member 6A is rotated to change the distance from the rotation center to the pressure contact surface, so that the sandwiching strength can be easily adjusted according to the rotation amount.

7 and 8 show the main part of a servo valve according to the third embodiment of the present invention.
In this case, as shown in FIG. 7, the projection 41c is provided on the sleeve 41 in the same manner as in the second embodiment described above, and the sleeve 41 is sandwiched between the pin members 6 and 6B inserted into the casing 40. Yes.
Among the pin members 6 and 6B, the pin member 6B is a spring pin provided with a notch 8 extending over the entire length in the circumferential direction as shown in FIG. The protrusion 41 c is sandwiched between the force and the other pin member 6.

  According to this embodiment, the sleeve 41 is held by the casing 40 by sandwiching the projection 41c between the two pin members 6 and 6B inserted into the casing 40, and cooperates with the pin member 6 by the elastic force of the pin member 6B. Since the projections are interposed between the two pin members 6 and 6b, there is no fear that both the pin members 6 and 6b fall off from the sleeve 41 and the casing 40. Therefore, basically the same effects as those of the first and second embodiments can be obtained.

9 and 10 show the main part of a servo valve according to a fourth embodiment of the present invention.
In this embodiment, as shown in FIG. 9, a protrusion 41 d is formed on the outer periphery of the sleeve 41, while a holding body that sandwiches the protrusion 41 d is formed in the casing 40.
The protrusions 41d are formed at equal intervals along the longitudinal direction of the sleeve around the reference position C in the sleeve 41. The holding body for sandwiching the protrusion 41d is composed of a pair of sandwiching arms 40c and 40c projecting from the inner wall of the casing 40 toward the protrusion 41d. The interval between the holding arms 40c and 40c is slightly narrower than the width of the protrusion 41d.
When the casing 40 is assembled with the sleeve 41 built-in, as shown in FIG. 10, the clamping arms 40 c and 40 c sandwich the projection 41 d in the longitudinal direction of the sleeve 41, so that the sleeve 41 is attached to the casing 40. It is supposed to be retained.

  Therefore, according to this embodiment, since the protrusion 41d of the sleeve 41 is sandwiched between the holding arms 40c and 40c projecting from the casing 40 and the reference position of the sleeve 41 is held in the casing 40, the casing 40 and the sleeve 41 It is possible to prevent the relative displacement between the two without regard to expansion / contraction, and therefore basically the same effects as those of the first to third embodiments can be obtained.

  In the embodiment described above, the specific configuration of the main components (nozzle flapper mechanism, casing, sleeve, piston) of the servo valve is not limited to the illustrated example. In short, the initial function can be obtained. Good.

It is sectional drawing which shows the servo valve which concerns on 1st Embodiment of this invention. It is an explanatory side view which shows the casing and sleeve of a servo valve. It is a schematic front view which similarly shows the casing and sleeve of a servo valve. FIG. 4 is an enlarged explanatory view corresponding to an arrow A in FIG. 3. It is explanatory drawing corresponding to FIG. 3 which shows the principal part of the servo valve which concerns on 2nd Embodiment of this invention. It is an expansion explanatory view corresponding to the B arrow of Drawing 5 showing a servo valve similarly. It is explanatory drawing which shows the principal part of the servo valve which concerns on 3rd Embodiment of this invention. It is a perspective view which shows a pin member. It is explanatory drawing which shows the principal part of the servo valve which concerns on 4th Embodiment of this invention. It is explanatory drawing which shows the relationship between a casing and a sleeve when a casing is formed.

Explanation of symbols

1 Servo valve 6, 6A, 6B Pin member (holding body)
7 Smoothing section 30 Nozzle flapper function (nozzle flapper)
40 Casing 40c Holding arm (holding body)
41 Sleeve 41b, 41c, 41d Protrusion 42 Piston

Claims (7)

A casing having a nozzle flapper and a sleeve for guiding a piston connected to the nozzle flapper are provided, and the flow rate of hydraulic oil is determined by the relative position between the piston and the sleeve based on the correspondence between the nozzle flapper and the piston. Servo valve
The sleeve is provided with a protrusion at a reference position corresponding to the neutral position of the piston, and the casing is provided with a holding body for holding the sleeve by sandwiching the protrusion in the longitudinal direction of the sleeve. Servo valve. The servo valve according to claim 1,
The protrusions are arranged to face each other with a gap in the longitudinal direction of the sleeve around the reference position of the sleeve, or provided with a desired length in the longitudinal direction around the reference position of the sleeve. Servo valve characterized by The servo valve according to claim 1 or 2,
The servo valve according to claim 1, wherein the holding body is two pin members that are inserted into a casing and sandwich the protrusion in the longitudinal direction of the sleeve. The servo valve according to claim 3,
One of the two pin members has a shape that sandwiches the protrusion in cooperation with the other pin member when rotated. The servo valve according to claim 4, wherein
Either one of the pin members is a round bar having a smooth portion on the outer periphery or an elliptical long shape. The servo valve according to claim 3,
The servo valve according to any one of the two pin members, wherein one of the pin members is a spring pin. The servo valve according to claim 1,
The servo valve according to claim 1, wherein the holding body is a pair of clamping arms that project from the casing toward the projection and sandwich the projection in the longitudinal direction of the sleeve.

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