JP6544066B2 - Variable throttle system and variable throttle type fluid bearing - Google Patents

Description

  The present invention relates to a variable throttle system and a variable throttle type fluid bearing provided with the variable throttle system.

  For example, Patent Document 1 discloses a variable throttle type hydrostatic bearing having a diaphragm type variable throttle. The diaphragm type variable throttle described in Patent Document 1 deforms the diaphragm using the pressure of the fluid which changes according to the bearing clearance distance which is the floating amount of the table which is the movable body, and between the diaphragm and the fluid flow path A variable stop is configured by making the stop gap distance, which is the gap between the two, variable. A convex portion is attached to a central portion of the diaphragm, and a concave portion for housing the convex portion is provided in the housing of the variable throttle so that the convex portion can slide in response to the deformation of the diaphragm. The convex portion of the diaphragm and the concave portion of the housing constitute a damper having a large damping property, and the vibration of the diaphragm is suppressed.

JP 2014-231857 A

  In the variable throttle type static pressure bearing described in Patent Document 1, after fluctuation of the bearing clearance distance occurs, the pressure of the fluid in the pocket fluctuates, and after the pressure of the fluid in the pocket fluctuates, the diaphragm and the fluid flow path The fluid pressure in the throttling gap fluctuates, and after the fluid pressure in the throttling gap fluctuates, the diaphragm deforms. Then, after the diaphragm is deformed and the throttle gap distance is changed, the flow rate of the fluid is adjusted. In addition, even if a fluid whose flow rate is adjusted is supplied to the pocket, the floating distance of a very large movable body is changed, so the bearing clearance distance does not actually change instantaneously, and a certain amount of delay After a lapse of time, the bearing clearance distance changes. That is, in the variable throttle type static pressure bearing described in Patent Document 1, the response is low. Further, since the variable throttle type static pressure bearing described in Patent Document 1 also includes a damper for suppressing vibration on the diaphragm, the load at the time of deformation of the diaphragm may increase, and the responsiveness may be further lowered.

  The present invention has been made in view of these points, and it is an object of the present invention to provide a variable throttle system capable of further improving response and a variable throttle type fluid bearing having the variable throttle system. Do.

  In order to solve the above-mentioned subject, a variable aperture system and a variable aperture type fluid bearing concerning the present invention take the following means. First, a first aspect of the present invention is a variable throttle that adjusts the flow rate of pumped fluid, supplies the fluid whose flow rate is adjusted to the fluid bearing, and causes the bearing member to rise from the bearing member by the bearing clearance distance. A system, which is supplied with a pumped fluid, supplies a fluid having an adjusted flow rate to the fluid bearing, and has a variable throttle means provided with an electric actuator for adjusting the flow rate of the fluid; and a drive for driving the electric actuator A circuit; and control means for controlling the electric actuator via the drive circuit. Then, the control means calculates a predicted bearing clearance distance which is a predicted bearing clearance distance based on the control state of the electric actuator without detecting an actual distance of the bearing clearance distance, and the calculated prediction The electric actuator is feedback-controlled so that the bearing clearance distance becomes a target distance.

  Next, according to a second aspect of the present invention, the flow rate of the pumped fluid is adjusted, the flow rate adjusted fluid is supplied to the fluid bearing, and the bearing member is floated from the bearing member by the bearing clearance distance. A throttling system, which is supplied with a pumped fluid, supplies a fluid with adjusted flow rate to the fluid bearing, and drives a variable throttling means including an electric actuator for adjusting the flow rate of the fluid, and the electric actuator It has a drive circuit, a control means which controls the said electrically-driven actuator via the said drive circuit, and a memory | storage means. The variable throttling means is disposed at a position opposed to a discharge flow path for discharging a fluid supplied to the fluid bearing and an opening serving as an inlet of the fluid to the discharge flow path, and the opening is deformed by bending deformation. And a diaphragm configured to make the diaphragm gap distance variable, and the electric actuator configured to flexibly deform the diaphragm based on a control signal from the control unit, the storage unit including the diaphragm The deflection amount / bearing clearance distance characteristic indicating the bearing clearance distance with respect to the deflection amount of the electric actuator and the electrical characteristic of the electric actuator are stored. Then, the control means includes the electric characteristics stored in the storage means, and an applied voltage which is a voltage applied to the electric actuator measured using a voltage detection means provided in the drive circuit. An estimated deflection amount, which is an estimated deflection amount of the diaphragm, is calculated based on a supply current that is a current supplied to the electric actuator measured using a current detection unit provided in the drive circuit. Alternatively, an actual deflection amount which is an actual deflection amount of the diaphragm is detected using a deflection amount detection means provided to the diaphragm, and the estimated deflection amount or the actual deflection amount and the storage means are stored. The predicted bearing clearance distance, which is the predicted bearing clearance distance, is calculated based on the deflection amount and the bearing clearance distance characteristic,受隙 distance between, so that the target distance, a feedback control of the said electric actuator.

  A third invention of the present invention is the variable throttle system according to the second invention, wherein the electrical characteristic stored in the storage means is a resistance value of the electric actuator, and the electric motor. The inductance of the actuator.

  Next, according to a fourth aspect of the present invention, in the variable throttle system according to the third aspect, the control means calculates the estimated deflection amount by applying the applied voltage, the resistance value, and the resistance value. The voltage based on the supplied current, the voltage based on the inductance and the supplied current, and the induced electromotive voltage of the electric actuator based on the displacement of the diaphragm according to the deflection of the diaphragm Calculate the estimated amount of deflection.

  Next, according to a fifth aspect of the present invention, there is provided a variable throttle system according to any one of the first to fourth aspects of the present invention, which supplies a fluid whose flow rate has been adjusted to the fluid bearing. And a fluid pumping means for pumping a fluid to the variable throttle type fluid bearing.

  According to the first aspect of the invention, feedback control is performed using a predicted bearing clearance distance that substitutes for the actual bearing clearance distance which has a low response and a certain delay time occurs before a change occurs. Even if the flow rate of the fluid is adjusted by controlling the electric actuator, the actual bearing gap distance changes after a certain delay time has elapsed if the mass of the bearing member (movable body) is very large. However, the predicted bearing clearance distance is not an actual bearing clearance distance but a distance calculated by the control unit based on the control state of the electric actuator (a distance calculated by so-called simulation). That is, the predicted bearing clearance distance can be changed without generating a delay time after controlling the electric actuator to adjust the flow rate of the fluid. Therefore, it is possible to realize a variable aperture system which can further improve the response.

  According to the second aspect of the invention, as in the first aspect of the invention, feedback is performed using a predicted bearing clearance distance that substitutes for the actual bearing clearance distance which has a low response and a certain delay time occurs before a change occurs. Control. Also, the predicted bearing clearance distance is calculated based on the estimated deflection amount which is the estimated deflection amount of the diaphragm, or the actual deflection amount which is the deflection amount of the diaphragm actually detected, and the deflection amount and bearing clearance distance characteristics. Thus, the predicted bearing clearance distance can be calculated appropriately without causing a delay time. Therefore, it is possible to realize a variable aperture system which can further improve the response.

  According to the third invention, since the estimated deflection of the diaphragm is calculated based on the resistance value and inductance of the electric actuator, the voltage applied to the electric actuator, and the current supplied to the electric actuator, the diaphragm is more appropriately It is possible to calculate the estimated amount of deflection of

  According to the fourth invention, the estimated deflection of the diaphragm can be calculated more accurately.

  According to the fifth invention, it is possible to appropriately realize a variable throttle type fluid bearing provided with a variable throttle system capable of further improving the response.

It is a perspective view explaining the example of the appearance of the table feed device to which a variable throttle type fluid bearing is applied. It is II-II sectional drawing of the table feeder shown in FIG. It is a figure explaining the composition of a variable throttling system, and the composition of a variable throttling type fluid bearing. It is a flowchart explaining the example of the process sequence of the control means which comprises the variable aperture system. It is a figure explaining the voltage of each position of the equivalent circuit of the coil of the electrically-driven actuator which comprises the variable aperture system, and an equivalent circuit. It is a figure explaining the example of the amount of deflection and bearing gap distance characteristics memorized by the storage means which constitutes a variable throttling system.

Hereinafter, embodiments of a variable throttle system and a variable throttle type fluid bearing according to the present invention will be sequentially described with reference to the drawings.
● [Overall configuration of the table feed device 1 to which the variable throttle type fluid bearing is applied (Fig. 1, Fig. 2)]
FIGS. 1 and 2 show an example of a table feeding device 1 to which a variable throttle system and a variable throttle type fluid bearing of the present invention are applied. The table feeding device 1 is configured by a base 10 (corresponding to a bearing member) as a base, a table 20 (corresponding to a bearing member) as a movable body, and a back plate 21 provided on the table 20. Then, a plurality of pockets 31P are provided on the bearing surface which is the opposing surface of the base 10 and the table 20, and the flow rate is adjusted from each of the pockets 31P (that is, for the fluid bearing) from the variable throttling means 30. Fluid is supplied. A fluid having a predetermined pressure (constant pressure) is pumped to each of the variable throttle means 30 from a pump 50 (corresponding to a fluid pumping means). The fluid is, for example, hydraulic oil, but may be liquid or gas.

● [Configuration of variable throttle system 2 and variable throttle type fluid bearing 3 (Fig. 3)]
Next, the configuration of the variable throttle system 2 and the configuration of the variable throttle type fluid bearing 3 will be described with reference to FIG. The variable stop system 2 is composed of a variable stop means 30 and a control unit 40. The variable throttle type fluid bearing 3 is composed of a pocket 31 P, a variable throttle system 2 and a pump 50. One control unit 40 is associated with one variable throttling means 30.

  The variable throttling means 30 (variable throttling device) has a housing 31, a diaphragm portion 32, an electric actuator 33, a displacement detecting means 34, etc., and is accommodated in a recess provided on the bearing surface of the base 10 There is. The displacement detection means 34 may be omitted. The variable throttling means 30 is supplied with the fluid pumped from the pump 50 and supplies the fluid bearing whose flow rate is adjusted to the fluid bearing as described later.

  The housing 31 is a case accommodating the diaphragm portion 32, the electric actuator 33 and the displacement detection means 34. On the surface of the housing 31 facing the table 20, there are provided a convex portion 31T which continuously protrudes in an annular or polygonal ring shape, and a pocket 31P which is a concave portion formed on the inner side of the convex portion 31T. , Is provided. A discharge flow passage 31A, which is a through hole communicating the pocket 31P with the inside of the housing 31, is provided substantially at the center of the pocket 31P. On the opposite side of the pocket 31P in the discharge flow passage 31A, a flow passage member 31B having a throttling surface 31C facing the diaphragm 32A is provided so as to protrude toward the diaphragm 32A. A diaphragm gap having a diaphragm gap distance S is formed between the diaphragm surface 31C and the diaphragm 32A. Further, a substantially central portion of the diaphragm 32A is disposed at a position facing the opening 31K which is an inlet of the fluid Q to the discharge flow channel 31A.

  The diaphragm portion 32 is composed of a diaphragm 32A and a support member 32B for supporting the edge of the diaphragm 32A. The support member 32 </ b> B is fixed to the housing 31 or is a part of the housing 31. The diaphragm 32A is, for example, a member having a substantially disc shape made of a steel plate of a spring material, and the edge thereof is supported by the support member 32B. The diaphragm 32A divides the space in the housing 31 into the supply chamber 35A and the storage chamber 35B, and is flexed and deformed according to the pressure difference between the supply chamber 35A and the storage chamber 35B. The fluid Q pressure-fed from the pump 50 at a predetermined pressure (constant pressure) flows into the storage chamber 35B and the supply chamber 35A as shown by the alternate long and short dash line in FIG. And flows into the discharge flow path 31A via the throttling gap of the throttling gap distance S. Then, the fluid Q that has flowed into the discharge flow passage 31A is discharged from the discharge flow passage 31A to the pocket 31P, and the table 20 is floated by the bearing clearance distance H. Further, one end of the connecting member 33B is fixed to a substantially central portion of the diaphragm 32A.

  The electric actuator 33 is composed of a permanent magnet 33F, which is a fixed part, and a movable part 33V that reciprocates in the vertical direction in FIG. The movable portion 33V is configured of a coil 33C, a drive base 33A, and a connecting member 33B. One end of the connection member 33B is fixed to a substantially central portion of the diaphragm 32A, and the other end is fixed to the drive base 33A. The drive base 33A is a member that mediates connection between the connecting member 33B and the coil 33C, and is formed, for example, in a disk shape, the other end of the connecting member 33B is fixed to one surface, and the coil 33C is fixed. The coil 33C is formed in a substantially cylindrical shape by a conductive wire wound so as to go around the permanent magnet 33F. The coil 33 </ b> C is capable of reciprocating in the vertical direction in FIG. 3 in accordance with the current supplied from the control unit 40. When the coil 33C moves upward, the diaphragm 32A is pushed upward through the drive base 33A and the connecting member 33B, and the diaphragm 32A is bent and deformed so as to be convex upward. When the coil 33C moves downward, the diaphragm 32A is pulled downward via the drive base 33A and the connecting member 33B, and the diaphragm 32A is bent and deformed so as to be convex downward. Thus, the electric actuator 33 adjusts the throttle gap distance S by bending and deforming the diaphragm 32A to adjust the flow rate of the fluid.

  The displacement detection means 34 is, for example, a displacement sensor, provided on the drive base 33A, and outputs a detection signal regarding the distance D to the support member 32B to the control means. The control means can detect the amount of displacement from the drive base 33A to the support member 32B based on the detection signal from the displacement detection means. That is, based on the detection signal from the displacement detection means 34, the control means can detect the actual deflection amount which is the actual deflection amount of the diaphragm 32A. As described later, the displacement detection means 34 may be omitted, and the estimated deflection amount which is the deflection amount of the diaphragm 32A estimated by the calculation by the control means may be calculated.

  The control unit 40 (control device) includes a drive circuit 42, terminals 44A and 44B, current detection means 45, storage means 43, control means 41 and the like.

  The drive circuit 42 is a circuit for supplying a current to the coil 33C, and outputs a current flowing from the terminal 44A to the terminal 44B via the coil 33C based on a control signal from the control means 41. The terminal 44A and one end of the coil 33C, and the terminal 44B and the other end of the coil 33C are connected by conductive wires, respectively. The voltage Va which is the voltage of the terminal 44A is detected by the control means 41 via a voltage detection means (voltage detection circuit) not shown, and the voltage Vb which is the voltage of the terminal 44B is a voltage detection means (voltage detection circuit not shown) ) Is detected by the control means 41. Therefore, the control means 41 can calculate the applied voltage E which is the voltage applied to both ends of the coil 33C by calculating the voltage Va-voltage Vb (applied voltage E = voltage Va-voltage Vb) .

  The supply current i supplied from the terminal 44A to the coil 33C returns to the terminal 44B and then flows to the ground via the current detection means 45 (current detection circuit). The current detection unit 45 is, for example, a shunt resistor whose resistance value (r) is known in advance, and the control unit 41 detects the voltage Vi of the current detection unit 45 and detects the detected voltage Vi and the resistance of the current detection unit 45 Based on the value (r), the supply current i supplied to the coil 33C can be calculated (supply current i = voltage Vi / resistance value r).

  The storage unit 43 (storage device) is, for example, a storage device such as a flash ROM. The storage means 43 includes values of a proportional constant K (details will be described later) when obtaining an induced voltage according to the electrical characteristics of the coil 33C and the deflection amount (moving speed) of the diaphragm 32A, deflection amount, bearing A gap distance characteristic (details will be described later), a control program, and the like are stored. The electrical characteristics of the coil 33C stored in the storage means 43 are, for example, the resistance value and the inductance of the coil 33C.

  The control unit 41 is, for example, a CPU, and executes processing of a processing procedure described later based on the control program read from the storage unit 43. The control means 41 receives detection signals of the voltage Va and the voltage Vb from voltage detection means (not shown), and calculates the voltage Va and the voltage Vb based on the received detection signals. Further, based on the detection signal from the displacement detection means 34, the control means 41 calculates an actual deflection amount which is the actual deflection amount of the diaphragm 32A. Further, as described above, the control means 41 detects the applied voltage E based on the voltage Va and the voltage Vb and the supply current i, and estimates them based on these and the electrical characteristics stored in the storage means 43. The estimated deflection amount which is the deflection amount of the diaphragm 32A is calculated. The target distance, which is the target of the bearing clearance distance H, may be configured to be input to the control means 41 from a control device external to the control unit 40, or be stored in advance in the storage means 43. May be

[Process of control means 41 (FIGS. 4 to 6)]
Next, an example of the processing procedure of the control means 41 will be described using the flowchart shown in FIG. For example, the control means 41 starts the process shown in FIG. 4 at predetermined time intervals (every 1 [ms] or the like).

  In step S10, the control means 41 acquires a target distance which is a target bearing clearance distance H, and proceeds to step S20. The target distance may be obtained from a control device other than the control unit 40 by communication or the like, or may be previously stored in the storage unit 43.

  At step S20, the control means 41 detects the applied voltage E and the supplied current i, and proceeds to step S30. As described above, the control unit 41 detects the voltage Va and the voltage Vb shown in FIG. 3 and obtains the applied voltage E from [voltage Va−voltage Vb]. Further, the control means 41 detects the voltage Vi shown in FIG. 3 and obtains the supply current i from [voltage Vi / resistance value r of the current detection means 45].

  In step S30, the control means 41 calculates an estimated deflection amount which is an estimated deflection amount of the diaphragm, or detects an actual deflection amount which is an actual deflection amount of the diaphragm based on a detection signal from the displacement detecting means. Then, the process proceeds to step S40. The procedure for calculating the estimated deflection amount will be described in detail below with reference to FIG.

[Step of calculating estimated deflection amount]
FIG. 5 shows an equivalent circuit of the coil 33C in the electric actuator 33 shown in FIG. As shown in FIG. 3, the coil 33C is connected between the terminal 44A and the terminal 44B, and the supply current i is supplied from the terminal 44A. The voltage between the terminals 44A and 44B is an applied voltage E (see FIG. 3). The equivalent circuit of the coil 33C can be regarded as a circuit in which a resistor 33CR having an armature resistance value R and a coil 33CL having an (armature) inductance L are connected in series as shown in FIG. Here, the voltage applied to the resistor 33CR can be represented by the product (= R * i) of the armature resistance value R and the supply current i. The voltage applied to the coil 33CL can be expressed by the product (= L * di / dt) of the (armature) inductance L and the amount of change of the supply current i per unit time. When the coil 33C operates, an induced voltage e is generated based on the movement amount (moving speed) of the coil 33C corresponding to the deflection amount of the diaphragm. Therefore, as shown in FIG. 5, the following (formula 1) is established.
E = [R * i] + [L * di / dt] + e (Expression 1)

Here, the induced electromotive voltage e can be represented by the product (= K * dx / dt) of the proportional constant K and the amount of change of the position x of the coil per unit time. Substituting this into (Expression 1), the following (Expression 2) can be obtained. Here, x is the amount of movement in the vertical direction in FIG. 3, and the proportional constant K is known in advance.
E = [R * i] + [L * di / dt] + [K * dx / dt] (equation 2)

Furthermore, based on transient phenomenology, replace with time derivative of current di / dt = (d / dt) * i = si, replace with time derivative of position dx / dt = (d / dt) * x = sx The above (formula 2) can be expressed by the following (formula 3).
E = [R * i] + [L * si] + [K * sx] (Equation 3)

If the above (formula 3) is arranged, the following (formula 4) can be obtained. In equation (4), x corresponds to the estimated deflection amount. As described above, R is the (armature) resistance value of the coil 33C stored in the storage means, and L is the (armature) inductance of the coil 33C stored in the storage means. Further, as shown in FIG. 3, the applied voltage E can be obtained from the voltage Va and the voltage Vb, and the supply current i is the voltage Vi shown in FIG. Can be obtained from Therefore, the control means 41 can calculate the estimated deflection (= x) of the diaphragm by using (Equation 4).
x = [E− (R + sL) i] / [sK] (Equation 4)

  Returning to the flowchart of FIG. 4, in step S40, the control means 41 calculates the estimated deflection of the diaphragm calculated in step S30, or the actual deflection of the detected diaphragm, and the deflection and bearing clearance stored in the storage. Based on the distance characteristics, the predicted bearing clearance distance which is the predicted bearing clearance distance is calculated, and the process proceeds to step S50.

  Here, the deflection amount and the bearing clearance distance characteristics will be described with reference to FIG. For example, the deflection amount / bearing clearance distance characteristic is a graph (also referred to as a map) in which the horizontal axis is the deflection amount (estimated deflection amount or actual deflection amount) and the vertical axis is the bearing clearance distance. The deflection amount and bearing clearance distance characteristics are set, for example, by setting the deflection amount to various values using the actual table feeding device 1 shown in FIGS. 1 and 2 and actually performing the bearing clearance distance at each deflection amount. Measure to create. Alternatively, the virtual model of the table feeder 1 is simulated and created. Alternatively, it may be created from various characteristics known in advance (a graph showing the amount of deflection with respect to the pressure applied to the pocket, a graph showing the bearing clearance distance with respect to the pressure applied to the pocket, etc.). There is no particular limitation on the method of creating the deflection amount and bearing clearance distance characteristics. The control means 41 uses the deflection amount and bearing clearance distance characteristics shown in FIG. 6 and the estimated deflection amount calculated in step S30 or the detected actual deflection amount to determine the estimated deflection amount (or the actual deflection amount). The corresponding bearing clearance distance is determined, and the determined bearing clearance distance is taken as a predicted bearing clearance distance. Thus, the control means 41 calculates the predicted bearing clearance distance based on the control state of the electric actuator.

  In step S50, the control means 41 calculates the deviation between the target distance obtained in step S10 and the predicted bearing clearance distance obtained in step S40, and proceeds to step S60. Note that deviation = target distance-predicted bearing clearance distance.

  At step S60, the control means 41 calculates a control amount (current) based on the deviation, and proceeds to step S70. The method of calculating the control amount is not particularly limited.

  In step S70, the control means 41 starts outputting a control signal (for example, a PWM [Pulse Width Modulation; signal corresponding to the control amount and the power supply voltage) corresponding to the control amount (current) to perform processing. finish.

  As described above in the present embodiment, the control means 41 does not detect the actual bearing clearance distance H shown in FIG. 3, and the predicted bearing clearance distance calculated by the control means 41 is the target distance. The current supplied to the coil of the electric actuator is feedback-controlled as follows. Therefore, even if the mass is very large and the delay time until the actual bearing clearance distance changes is large, the predicted bearing clearance distance that changes instantaneously regardless of the mass is used, so the response is further improved. be able to. For this reason, dynamic rigidity can be greatly improved as compared with the case where feedback control is performed so that the actual bearing clearance distance becomes the target distance.

  Various modifications, additions, and deletions of the variable throttle system and the variable throttle type fluid bearing according to the present invention can be made without departing from the scope of the present invention. For example, the processing procedure of the control means is not limited to the flowchart shown in FIG. Further, although the example in which the variable throttling means 30 is provided on the bearing surface of the base 10 has been described in the present embodiment, the variable throttling means 30 may be provided on the bearing surface of the table 20.

  The variable throttling system and the variable throttling fluid bearing described in the present embodiment are not limited to the table feeding device, and can be applied to various devices. For example, the variable throttling system and the variable throttling fluid bearing described in the present embodiment can be applied to a main shaft of a machine tool whose bearing surface is not a flat surface but a cylindrical surface.

  The fluid bearing described in the present embodiment includes a hydrostatic bearing.

1 table feed device 2 variable throttle system 3 variable throttle type fluid bearing 10 base (bearing member)
20 Table (bearing member)
Reference Signs List 21 back plate 30 variable throttling means 31 housing 31A discharge flow path 31B flow path member 31C throttle surface 31K opening 31P pocket 32 diaphragm portion 32A diaphragm 32B support member 33 electric actuator 33A drive base 33B connection member 33C coil 33F permanent magnet 34 displacement detection Means 35A Supply chamber 35B Reservoir 40 Control unit 41 Control means 42 Drive circuit 43 Storage means 44A, 44B terminal 45 Current detection means 50 Pump (fluid pumping means)
D distance H Bearing clearance distance S Throttle clearance distance

Claims (4)

What is claimed is: 1. A variable throttling system for adjusting the flow rate of pumped fluid and supplying the fluid with the adjusted flow rate to a fluid bearing to cause a bearing member to rise from a bearing member by a bearing clearance distance,
Variable throttling means provided with a motor-driven actuator that is supplied with pumped fluid, supplies flow-regulated fluid to the fluid bearing, and regulates the flow rate of the fluid;
A drive circuit for driving the electric actuator;
Control means for controlling the electric actuator via the drive circuit;
Storage means, and
The variable aperture means is
A discharge passage for discharging a fluid to be supplied to the fluid bearing;
A diaphragm disposed at a position opposite to an opening serving as an inlet of the fluid to the discharge flow channel, and capable of changing a diaphragm gap distance formed between the opening and the opening by bending deformation;
And the electric actuator that elastically deforms the diaphragm based on a control signal from the control means.
The storage means
A deflection amount / bearing clearance distance characteristic indicating the bearing clearance distance with respect to a deflection amount of the diaphragm, and an electrical characteristic of the electric actuator are stored.
The control means
An applied voltage which is a voltage applied to the electric actuator measured using the electric characteristic stored in the storage means and a voltage detection means provided in the drive circuit; The estimated deflection amount which is the estimated deflection amount of the diaphragm is calculated based on the supply current which is the current supplied to the electric actuator measured using the current detection means, or provided on the diaphragm The actual deflection amount, which is the actual deflection amount of the diaphragm, is detected using the specified deflection amount detection means,
An estimated bearing clearance distance which is a predicted bearing clearance distance is calculated based on the estimated deflection amount or the actual deflection amount, and the deflection amount and bearing clearance distance characteristics stored in the storage means,
The electric actuator is feedback-controlled so that the calculated predicted bearing clearance distance becomes a target distance.
Variable aperture system. The variable aperture system according to claim 1 , wherein
The electrical characteristics stored in the storage means are a resistance value of the electric actuator and an inductance of the electric actuator.
Variable aperture system. The variable stop system according to claim 2 ,
When the control means calculates the estimated amount of deflection, the amount of deflection is based on the applied voltage, a voltage based on the resistance value and the supplied current, a voltage based on the inductance and the supplied current, and a deflection amount of the diaphragm The estimated amount of deflection is calculated based on the induced electromotive voltage of the electric actuator based on the amount of movement of the diaphragm according to
Variable aperture system. The variable throttle system according to any one of claims 1 to 3, wherein a fluid whose flow rate is adjusted is supplied to the fluid bearing.
Fluid pumping means for pumping fluid to the variable throttle system;
Variable throttle fluid bearing.

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