JP5673015B2 - Servo valve - Google Patents

Description

  The present invention relates to a servo valve.

  Conventionally, a nozzle flapper-type servo valve includes a torque motor to which a control target current is input, a flapper that is rotationally driven by the torque motor, and a pair of nozzles that are disposed to face each other with the flapper in the middle, A spool for adjusting the valve opening degree connected to these nozzles via a pressure passage, and a feedback spring (feedback wire) for connecting the spool and the flapper are included (see Patent Document 1).

  In the nozzle flapper type servo valve having the above configuration, when a current corresponding to a control target is input to the coil of the torque motor, a magnetic force corresponding to the current is generated, and the generated magnetic force generates an armature (electric element) of the torque motor. Rotational torque is generated. The rotational torque generated in the armature tilts the flapper connected to the armature. As a result, the back pressure of the nozzle closer to the flapper is increased, and the back pressure of the nozzle away from the flapper is reduced.

  The back pressure that is increased due to the approach of the flapper is transmitted to one end side in the axial direction of the spool, and the back pressure that is decreased by the separation of the flapper is transmitted to the other end side in the axial direction of the spool. The spool is displaced according to the back pressure difference. This displacement causes the feedback spring to generate a torque in a direction opposite to the rotational torque of the armature. A pulling back force is applied to the flapper so that the back pressures of both nozzles become equal, and the spool is stopped at a position where the back pressures are equal. As a result, the stop position of the spool is maintained at the valve opening corresponding to the control target input current.

  The nozzle flapper servo valve is configured to be supplied with a filtered fluid. This is because if the liquid supplied to the nozzle flapper type servo valve contains impurities, the flow path of the liquid and the nozzle opening are clogged with impurities, and the servo valve function is impaired. is there.

JP 2001-12409 A

  However, the conventional servo valve is configured such that the liquid supplied to the nozzle is filtered and then supplied to the nozzle. However, the filter is clogged or the nozzle is clogged with impurities. If this happens, the back pressure corresponding to the control target cannot be obtained, and the performance of the servo valve may be reduced. Conventionally, there is no measure for eliminating or suppressing clogging of the filter or nozzle, and it has been necessary to periodically replace the filter or to periodically clean the filter or nozzle.

  For example, when a servo valve is used in a fuel control unit of a fuel system of a jet engine, that is, a servo valve supplies fuel supplied from a fuel pump to a fully automatic digital engine control device (Full Authority Digital Electronics Control (FADEC)). When supplying to the jet engine based on the command, the fuel supplied from the fuel pump is used as the liquid supplied to the nozzle, but if the filter or nozzle is clogged due to impurities in the fuel, the servo valve Therefore, it is necessary to replace the filter regularly or to clean the filter and nozzle regularly.

  The present invention has been made in view of the above-described problems, and an object of the present invention is to eliminate or prevent clogging of a filter and a nozzle in a servo valve.

  The present invention adopts the following configuration as means for solving the above-described problems.

  A first invention is a servo valve that adjusts a flow rate of liquid by adjusting a back pressure acting on both ends of a spool and moving the spool, the nozzle flapper in which an inclination angle is adjusted by a torque motor, A first flow path having a first nozzle arranged to face one side of the nozzle flapper and connected to one end of the spool, and arranged to face the other side of the nozzle flapper A second flow path having a second nozzle that is connected to the end of the spool different from the first flow path, and a reverse flow that reverses the flow of the liquid in the first flow path and the second flow path And a means comprising the means.

  According to a second aspect of the present invention, in the first aspect of the present invention, the pair of the first nozzle and the second nozzle are arranged to face each other with the nozzle flapper interposed therebetween, and the backflow means includes one pair of the first nozzle and the second nozzle. A configuration of a pressure switching mechanism that switches a height relationship between the pressure in the first region facing the second nozzle and the pressure in the second region facing the other pair of the first nozzle and the second nozzle is employed.

  According to a third invention, in the second invention, following the height relationship between the pressure in the first region and the pressure in the second region, the end of the spool to which the first flow path is connected and the above-mentioned A configuration is adopted in which a flow path switching mechanism for switching between the end of the spool to which the second flow path is connected is provided.

  According to a fourth invention, in the third invention, the pressure switching mechanism and the flow path switching mechanism are driven by a single solenoid.

  According to the present invention, the flow of the first flow path having the first nozzle disposed opposite to the one surface of the nozzle flapper and connected to one end of the spool, and the other side of the nozzle flapper And the second flow path connected to the end of the spool different from the first flow path is made to flow backward by the reverse flow means. The filter provided in the flow path can be automatically cleaned, and clogging of the filter and nozzle can be eliminated or suppressed.

It is a schematic block diagram of the servo valve in one Embodiment of this invention. It is a schematic block diagram of the servo valve in one Embodiment of this invention when the flow path of a drive liquid is switched.

  Hereinafter, a servo valve according to an embodiment of the present invention will be described with reference to the drawings. In the following drawings, the scale of each member is appropriately changed in order to make each member a recognizable size.

FIG. 1 is a schematic configuration diagram of a servo valve SV according to an embodiment of the present invention.
The servo valve SV includes a nozzle flapper mechanism 1, a spool valve mechanism 10, a switching mechanism 20, and filters F1 and F2. These filters F1 and F2 are made of braided or sintered metal nets having eyes of about 20 to 40 μm.

The nozzle flapper mechanism 1 includes a nozzle flapper 2, upper nozzles 3a and 3b, lower nozzles 4a and 4b, and a feedback spring 5.
The nozzle flapper 2 is made of a flat plate material, and is configured to be able to rotate (tilt) about a rotation shaft 2a provided at the center position thereof. The rotary shaft 2a is integrally connected to an armature (electric element) of a torque motor (not shown). Therefore, when a current corresponding to the control target is input to the coil of the torque motor, a magnetic force corresponding to the input current is generated to generate a rotational torque in the armature of the torque motor, and the nozzle flapper 2 is tilted at a predetermined inclination angle. Can be made.

The upper nozzles 3a and 3b are disposed on the upper side of the nozzle flapper 2 around the rotation shaft 2a. These upper nozzles 3a and 3b are a pair of nozzles arranged opposite to each other with the nozzle flapper 2 interposed therebetween, and are arranged facing the first region α in the first chamber 6a.
The lower nozzles 4a and 4b are disposed on the lower side of the nozzle flapper 2 with the rotating shaft 2a as the center. These lower nozzles 4a and 4b are a pair of nozzles arranged to face each other with the nozzle flapper 2 interposed therebetween, and are arranged facing the second region β in the second chamber 6b.

In addition, as shown in FIG. 1, the upper nozzle 3a and the lower nozzle 4a are arrange | positioned facing the surface of the one side of the nozzle flapper 2, and function as a 1st nozzle of this invention. That is, the servo valve SV of the present embodiment includes two first nozzles according to the present invention.
Further, the upper nozzle 3b and the lower nozzle 4b are disposed so as to face the other surface of the nozzle flapper 2, and function as the second nozzle of the present invention. That is, the servo valve SV of the present embodiment includes two second nozzles in the present invention.
As described above, the upper nozzles 3a and 3b are paired and the lower nozzles 4a and 4b are paired. That is, the servo valve SV of the present embodiment includes two pairs of first nozzles and second nozzles, that is, two pairs of first nozzles and second nozzles.

In addition, the servo valve SV of the present embodiment has a U-shaped first connection flow path A (first flow path) that connects the upper nozzle 3a and the lower nozzle 4b facing one surface of the nozzle flapper 2. It has. That is, the servo valve SV of the present embodiment includes the first connection flow path A having the upper nozzle 3a (first nozzle) and the lower nozzle 4a (first nozzle).
Furthermore, the servo valve SV of the present embodiment has a U-shaped second connection flow path B (second flow path) that connects the upper nozzle 3b and the lower nozzle 4b facing the other surface of the nozzle flapper 2. It has. That is, the servo valve SV of the present embodiment includes the second connection channel B having the upper nozzle 3b (second nozzle) and the lower nozzle 4b (second nozzle).

  A flow path L3 with a filter F1 interposed therebetween is connected to the first chamber 6a facing the upper nozzles 3a and 3b. A flow path L6 with a filter F2 interposed therebetween is connected to the second chamber 6b facing the lower nozzles 4a and 4b. The first connection channel A is connected to a later-described channel L23, and the second connection channel B is connected to a channel L20.

  The feedback spring 5 is composed of a long spring member sometimes called a feedback wire. The upper end side of the feedback spring 5 is fixed to the lower end side of the nozzle flapper 2. Further, the lower end side of the feedback spring 5 extends in the same direction as the longitudinal direction of the nozzle flapper 2, and the tip portion is connected to a spool 12 described later of the spool valve mechanism 10. When the feedback spring 5 is moved by the tilt of the nozzle flapper 2, the spool 12 of the spool valve mechanism 10 can be moved (displaced) in the axial direction.

The spool valve mechanism 10 is configured by disposing a spool 12 in a casing 11 so as to be movable, similarly to a known spool valve mechanism. The spool valve mechanism 10 is configured such that a spool 12 is disposed in a casing 11 so as to be movable in an axial direction. The spool 12 is provided with four lands 13a to 13d at intervals along the axial direction. Among these lands 13a to 13d, the lands 13a and 13b are respectively provided at both end sides in the axial direction, and the lands 13c and 13d are respectively provided in the central portions in the axial direction. And the front-end | tip part of the feedback spring 5 is connected between land 13c, 13d.
Although omitted for simplification of the drawings, the casing 11 corresponding to the lands 13c and 13d provided in the center is provided with a liquid inlet / outlet port, and the lands 13c and 13d move ( The opening degree of the port, that is, the opening degree of the valve can be adjusted.

The switching mechanism 20 functions as the backflow means, pressure switching mechanism, and flow path switching mechanism of the present invention.
The switching mechanism 20 reverses the liquid flow in the first connection flow path A and the second connection flow path B. More specifically, the switching mechanism 20 switches the first connection by switching the height relationship with the pressure of the second region β facing the lower nozzle 4a, 4b of the first region α facing the upper nozzle 3a, 3b. The liquid flow in the flow path A and the second connection flow path B is reversed.
Further, the switching mechanism 20 follows the height relationship between the pressure in the first region α and the pressure in the second region β, and the end of the spool 12 to which the first connection flow path A is connected and the second connection flow path B. Is switched to the end of the spool 12 to which the

The switching mechanism 20 includes a casing 21, a valve body 22, and a single solenoid SO.
The casing 21 has a space in which the valve body 22 can move. In FIGS. 1 and 2, a liquid inlet / outlet port is provided at a portion connected to a later-described flow path indicated by a thick line and a thin line.
The valve body 22 includes a shaft 23 and lands 24a to 24f that are provided integrally with the shaft 23 and are arranged at a distance (six in the illustrated example). The valve body 22 is provided so as to be movable in the axial direction in the casing 21 and is provided on one end side (left end side in the illustrated example) of the valve body 22 in the axial direction. The coil spring 25 is always pressed to the solenoid SO side.
The arrangement of the lands 24a to 24f provided on the shaft 23 of the valve body 22 and the arrangement relation of the liquid inlet / outlet ports provided on the casing 21 can realize the liquid flow in the description of the control operation described later. It has been decided.
The solenoid SO is provided on the other end side in the axial direction of the valve body 22, and when the solenoid SO is turned on, the solenoid rod SOL extends to move the valve body 22 against the coil spring 25. (See FIG. 1). When the solenoid SO is turned off, the valve body 22 is pressed by the coil spring 25 so that the valve body 22 can be moved to the solenoid SO side (see FIG. 2).

  The flow paths L1 to L9 and L20 to L27 are liquid paths, and the flow paths L1 to L9 are disposed between the nozzle flapper mechanism 1 and the switching mechanism 20, and the flow paths L20 to L27 are the nozzle flapper mechanism 1 and the spool valve. It is disposed between the mechanism 10 and the switching mechanism 20.

  Here, in the servo valve SV of the present embodiment, the flow path L23 is connected to the first connection flow path A, and the connection destination of the flow path L23 is connected to one end side of the spool 12 by the switching mechanism 20. The path L24 and the flow path L27 connected to the other end side of the spool 12 are configured to be switchable. The flow path L20 is connected to the second connection flow path B, and the connection destination of the flow path L20 is connected to the flow path L26 connected to one end side of the spool 12 and the other end side of the spool 12 by the switching mechanism 20. The flow path L21 is configured to be switchable. The first connection flow path A and the second connection flow path B are always connected to different ends of the spool 12 by the switching mechanism 20.

In the servo valve SV of the present embodiment, the connection destination of the flow path L1 can be switched by the switching mechanism 20 between the flow path L2 connected to the first area α and the flow path L5 connected to the second area β. It is configured.
Further, the connection destination of the flow path L9 is configured to be switchable between the flow path L7 connected to the first region α and the flow path L8 connected to the second region β by the switching mechanism 20.

  The filter F1 is provided in the flow path L3, and is configured to capture impurities contained in the liquid flowing in the flow path L3. The filter F2 is provided in the flow path L6 and is configured to capture impurities contained in the liquid flowing in the flow path L6.

Hereinafter, the operation of the servo valve SV configured as described above will be described.
First, aircraft fuel serving as a driving liquid is supplied to the servo valve SV. Here, high pressure fuel (hereinafter referred to as high pressure liquid) is supplied to the flow path L1, and low pressure fuel (hereinafter referred to as low pressure liquid) is supplied to the flow path L9. For example, the high-pressure fuel is supplied from the downstream side of the fuel pump mounted on the aircraft, and is supplied from the upstream side of the fuel pump of low-pressure fuel.

Now, it is assumed that the solenoid SO is turned on and the solenoid rod SOL is extended to move the valve element 22 to the left against the coil spring 25 as shown in FIG. In the figure, the bold line indicates the direction in which the liquid is about to flow.
In this case, the high-pressure liquid is guided to the first region α in the first chamber 6a through the flow paths L1, L2 and L3 with the filter F1 interposed. In the filter F1, impurities contained in the driving liquid are captured and the impurities are prevented from flowing into the first chamber 6a. At this time, the high-pressure liquid is prevented from flowing into the flow path L5 by closing the flow path L5 with the land 24b.
The low-pressure liquid is guided to the second region β in the second chamber 6b through the flow paths L9, L8, and L6. At this time, the flow path L7 is closed by the land 24c so that the low-pressure liquid does not flow into the flow path L7.

The nozzle flapper 2 is tilted so as to approach the upper nozzle 3a and the lower nozzle 4b and away from the upper nozzle 3b and the lower nozzle 4a. Then, the high-pressure fluid flows into the second connection flow path B. As a result, the second connection flow path B becomes high pressure, and the first connection flow path A becomes low pressure.
The nozzle flapper 2 is tilted as described above by the rotational torque generated in the armature (electric element) of the torque motor (not shown). This tilting state is kept constant by the feedback spring 5 and the spool valve mechanism 10.
As described above, when the second connection flow path B becomes high pressure and the first connection flow path A becomes low pressure, the fuel flows from the high pressure side to the low pressure side as shown by the thick arrow in FIG. Specifically, the fuel flows in the order of the flow path L1, the flow path L2, the flow path L3, the flow path L6, the flow path L8, and the flow path L9. At this time, the impurities in the fuel are processed by F1 and F2 or discharged from the flow path L9.

When the second connection flow path B becomes high pressure and the first connection flow path A becomes low pressure, the high pressure fluid flows into the land 13b side through the flow paths L20, L21, and L22, and the end face of the land 13b. The back pressure on the side becomes higher than the end face side of the land 13a, and a displacement force that moves the spool 12 from the land 13b side to the land 13a side acts (see arrow a in FIG. 1).
This displacement force causes the feedback spring 5 to generate a torque in a direction opposite to the rotational torque of the armature, and exerts a pulling force on the nozzle flapper 2 so that the back pressures of both nozzles 3a and 4b become equal, and the back pressures become equal. The spool 12 is stopped at the position. As a result, the valve opening corresponding to the control target input current input to the torque motor is realized.

Next, as shown in FIG. 2, it is assumed that the solenoid SO is turned off, the valve body 22 is pressed by the coil spring 25, and the valve body 22 is moved to the solenoid SO side.
This solenoid SO is turned ON / OFF periodically. For example, when the servo valve SV supplies the fuel supplied from the fuel pump to the jet engine based on a multi-system FADEC command, it can be performed when the system is switched, that is, when the CPU is switched. The solenoid SO may be turned ON / OFF by measuring the hydraulic pressure before and after the filter to clog the filter F1 or the filter F2.

When the solenoid SO is turned off, the high-pressure liquid is guided to the second region β in the second chamber 6b through the flow paths L1, L5 and L6 through which the filter F2 is interposed. In the filter F2, impurities contained in the driving liquid are captured and the impurities are prevented from flowing into the second chamber 6b. At this time, the high-pressure liquid is prevented from flowing into the flow path L1 by closing the flow path L1 with the land 24a.
The low-pressure liquid is guided to the first region α in the first chamber 6a through the flow paths L9, L7, and L1. At this time, the flow path L8 is closed by the land 24b so that the low-pressure liquid does not flow into the flow path L8.

Here, as in FIG. 1, the nozzle flapper 2 is tilted so as to approach the upper nozzle 3a and the lower nozzle 4b and away from the upper nozzle 3b and the lower nozzle 4a. Then, the high-pressure fluid flows into the first connection flow path A, and as a result, the first connection flow path A becomes high pressure and the second connection flow path B becomes low pressure.
Then, as described above, when the first connection flow path A becomes high pressure and the second connection flow path B becomes low pressure, the fuel flows from the high pressure side to the low pressure side as shown by the thick arrow in FIG. Specifically, the fuel flows in the order of the flow path L1, the flow path L5, the flow path L6, the flow path L3, the flow path L7, and the flow path L9.

  However, the switching mechanism 20 switches the flow path L24 and the flow path 27, and the flow path L26 and the flow path L21 are switched, so that the high-pressure fluid passes through the flow path L23, the flow path L27, and the flow path L22. As in the state shown in FIG. 1, the back pressure on the end surface side of the land 13b is higher than that on the end surface side of the land 13a, and the spool 12 is moved from the land 13b side to the land 13a side. A displacement force acts (see arrow a in FIG. 2). As a result, a valve opening degree corresponding to the control target input current input to the torque motor is realized.

According to the servo valve SV of the present embodiment, the switching mechanism 20 switches the level relationship between the pressure in the first region α facing the upper nozzles 3a and 3b and the pressure in the second region β facing the lower nozzles 4a and 4b. Thus, the liquid flow in the first connection flow path A and the second connection flow path B is reversed.
For this reason, the filters F1, F2 and the nozzles 3a, 3b, 4a, 4b can be automatically washed, and clogging of the filters and nozzles can be eliminated or suppressed.

In the servo valve SV of the present embodiment, the switching mechanism 20 causes the switching mechanism 20 to connect the first connection flow path A in accordance with the height relationship between the pressure in the first region α and the pressure in the second region β. The end portion of the spool 12 to be switched and the end portion of the spool 12 to which the second connection flow path B is connected are switched.
For this reason, the tilting direction of the nozzle flapper 2 and the moving direction of the spool 12 can always be matched to each other regardless of the height relationship between the pressure of the first connection channel A and the pressure of the second connection channel B.
Therefore, clogging of the filter and the nozzle can be eliminated or suppressed without changing the control at the time of adjusting the flow rate.

  As mentioned above, although preferred embodiment of this invention was described referring an accompanying drawing, it cannot be overemphasized that this invention is not limited to the said embodiment. Various shapes, combinations, and the like of the constituent members shown in the above-described embodiments are examples, and various modifications can be made based on design requirements and the like without departing from the gist of the present invention.

For example, in the above embodiment, the switching mechanism 20 is constituted by a spool valve, but it can also be implemented by a combination of a plurality of electromagnetic valves instead of the spool valve. However, if the spool valve is used as in the above-described example, the functions of the pressure switching mechanism and the flow path switching mechanism of the present invention can be combined, and the cost can be reduced.
In addition, for example, the liquid flow in the first connection flow path A and the second connection flow path B may be reversed using a pump or the like.
Moreover, you may add a filter to flow paths other than flow path L3, L6.

  SV: Servo valve, A: First region, B: Second region, 1 ... Nozzle flapper mechanism, 2 ... Nozzle flapper, 2a ... Rotating shaft, 3a, 3b ... Upper nozzle, 4a, 4b ... Lower nozzle, 5 ... feedback spring, 6a ... first chamber, 6b ... second chamber, 10 ... spool valve mechanism, 11 ... casing, 12 ... spool, 13a-13d ... land, 20 ... ... Switching mechanism (back flow means, pressure switching mechanism, flow path switching mechanism), 21 ... casing, 22 ... valve body, 23 ... shaft, 24a-24f ... land, SO ... solenoid, F1, F2 ... filter

Claims (4)

A servo valve that adjusts the flow rate of liquid by adjusting the back pressure acting on both ends of the spool and moving the spool;
A nozzle flapper whose inclination angle is adjusted by a torque motor;
A first flow path having two first nozzles arranged to face one surface of the nozzle flapper and connected to one end of the spool;
A second flow path having two second nozzles disposed opposite to the other surface of the nozzle flapper and connected to an end of the spool different from the first flow path;
A first chamber in which one of the two first nozzles and one of the two second nozzles are disposed;
A first pipe connected to the first chamber for supplying or discharging the liquid;
A first filter provided in the middle of the first pipe;
A second chamber in which the other of the two first nozzles and the other of the two second nozzles are disposed;
A second pipe connected to the second chamber for supplying or discharging the liquid;
A second filter provided in the middle of the second pipe;
By supplying the liquid so that the first pipe has a pressure higher than that of the second pipe during normal operation, the first pipe, the first chamber, the first flow path or the second flow path, The liquid is allowed to flow in the order of two chambers and the second pipe, and the liquid is supplied so that the second pipe has a higher pressure than the first pipe at the time of reverse flow, so that the second pipe, the second chamber, A reverse flow means for flowing a liquid in the order of the first flow path or the second flow path, the first chamber, and the first pipe, thereby reversely flowing the liquid in the first flow path and the second flow path. When,
A servo valve comprising: The backflow means includes a pressure switching mechanism that switches a level relationship between a pressure in a first region inside the first chamber and a pressure in a second region inside the second chamber. 1. The servo valve according to 1.   Following the height relationship between the pressure in the first region and the pressure in the second region, the end of the spool to which the first flow path is connected and the end of the spool to which the second flow path is connected The servo valve according to claim 2, further comprising a flow path switching mechanism that switches between the two.   4. The servo valve according to claim 3, wherein the pressure switching mechanism and the flow path switching mechanism are driven by a single solenoid.

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