Patent Description:
<CIT> discloses an electronic expansion valve, which is an example of known electric-operated valves. The electronic expansion valve is installed in an air conditioner. The electronic expansion valve includes a valve body, a valve member, and a stepping motor for moving the valve member. The valve body includes a valve port through which fluid flows. The valve member forms a variable throttle with the valve port. The stepping motor includes a rotor and a stator.

The air conditioner controls the electronic expansion valve based on the position of the rotor related to a valve opening point. The valve opening point is the number of pulses (a pulse number) input to the stepping motor to rotate the rotor from a position (a rotation limit position) where the rotation is limited by a stopper to a position (a valve opening position) at which the flow rate of the fluid in the valve port is at a predetermined set value. The valve opening point can vary depending on the component accuracy or assembly accuracy of the electric-operated valve. For this reason, the electronic expansion valve disclosed in <CIT> is provided with information related to the valve opening point obtained in the manufacturing process. The air conditioner can accurately control the flow rate of the electronic expansion valve using this information.

The electronic expansion valve disclosed in <CIT> measures the valve opening point on the basis of the flow rate of the fluid at the valve port, so that the measurement of the valve opening point is complicated. For this reason, a simple method for obtaining the position of the rotor as a reference for flow-rate control of the electric-operated valve has been desired.

<CIT> discloses an electric valve, wherein a valve stem is rotated in one direction and is moved downward by an elevation driving mechanism, which moves a valve member downward and brings the valve member into contact with a valve seat. Then, the valve member is further moved downward, withstanding the pushing force of a valve pushing spring, to a control origin position defined by a valve opening direction stopper mechanism that includes a movable stopper and a fixed stopper.

In assembling the electric valve, the valve stem is rotated in one direction, and the valve member is moved downward to an assembling reference position defined by an assembling stopper mechanism that includes a movable stopper and a fixed stopper, the assembling reference position being lower than the control origin position by a predetermined distance. Next, the valve stem is rotated in the other direction, and the valve member is moved upward by the predetermined distance, then the valve opening direction stopper mechanism is assembled. In the method for assembling the electric valve, the valve stem is reversed when the valve member reaches the assembling reference position.

Accordingly, it is an object of the present invention to provide an electric-operated valve in which the position of the rotor as a reference for flow-rate control can easily be obtained, a method of controlling the same, and a method of manufacturing the same.

The inventors eagerly examined the relationship between the valve opening point and the position of the rotor using a plurality of electric-operated valves. As a result, the inventors found that the numbers of pulses (pulse numbers) for rotating the individual rotors from a position where the valve members are in contact with the valve seats (a valve closing position) to a valve opening position do not vary in a plurality of electric-operated valves, and the pulse numbers are common among the plurality of electric-operated valves. The inventors also found that the numbers of pulses (pulse numbers) for rotating the individual rotors from a rotation limit position to the valve closing position vary among the plurality of electric-operated valves, and the pulse numbers are unique values in the individual electric-operated valves. From the findings, the inventors found the idea that the position of the rotor as a reference for flow-rate control can be obtained based on the valve closing position of the electric-operated valve. The present invention has been achieved based on the idea.

To achieve the above object, an electric-operated valve and a method of controlling such an electric-operated valve are provided according to the independent claims.

To achieve the above object, an electric-operated valve according to an aspect of the invention includes a valve body including a valve seat, a rotor rotatable with respect to the valve body, a stator constituting a stepping motor together with the rotor, a valve member that faces the valve seat and that is pushed toward the valve seat via a coil spring when the rotor rotates in a closing direction, a stopper that, when the rotor is at a rotation limit position where the rotor is further rotated in the closing direction from a valve closing position where the valve member is in contact with the valve seat, limits rotation of the rotor in the closing direction, and a control unit. The control unit (<NUM>) inputs a pulse to the stepping motor to rotate the rotor in the closing direction with a first torque, (<NUM>) upon detecting step-out of the stepping motor when rotating the rotor with the first torque (hereinafter referred to as "first step-out detection"), inputs the pulse to the stepping motor to rotate the rotor in the closing direction with a second torque, and (<NUM>) upon detecting step-out of the stepping motor when rotating the rotor with the second torque (hereinafter referred to as "second step-out detection"), obtains the number of pulses (a pulse number) input between the first step-out detection and the second step-out detection, wherein the first torque is a torque of a magnitude incapable of rotating the rotor in the closing direction to the rotation limit position, with the valve member in contact with the valve seat, and wherein the second torque is a torque of a magnitude capable of rotating the rotor in the closing direction to the rotation limit position while compressing the coil spring, with the valve member in contact with the valve seat.

To achieve the above object, a method of controlling an electric-operated valve according to another aspect of the invention is provided. The electric-operated valve includes a valve body including a valve seat, a rotor rotatable with respect to the valve body, a stator constituting a stepping motor together with the rotor, a valve member that faces the valve seat and that is pushed toward the valve seat via a coil spring when the rotor rotates in a closing direction, and a stopper that, when the rotor is at a rotation limit position where the rotor is further rotated in the closing direction from a valve closing position where the valve member is in contact with the valve seat, limits rotation of the rotor in the closing direction. The method includes:.

In the aspect of the invention, preferably, the method further includes (<NUM>) calculating information on the pulse number using the pulse number, wherein the information includes a pulse number that is input to the stepping motor to rotate the rotor from the rotation limit position to a valve opening position at which a fluid flow rate in a valve port enclosed by the valve seat is a set value.

According to an embodiment of the invention, a valve member is disposed so as to face a valve seat and is pushed toward the valve seat via a coil spring when a rotor rotates in a closing direction. When the rotor is at a rotation limit position where the rotor is further rotated in the closing direction from a valve closing position where the valve member is in contact with the valve seat, a stopper limits rotation of the rotor in the closing direction. (<NUM>) A pulse is input to the stepping motor to rotate the rotor in the closing direction with a first torque. (<NUM>) When step-out of the stepping motor is detected while the rotor is rotated with the first torque (hereinafter referred to as "first step-out detection"), the pulse is input to the stepping motor to rotate the rotor in the closing direction with a second torque. (<NUM>) When step-out of the stepping motor is detected while the rotor is rotated with the second torque (hereinafter referred to as "second step-out detection"), a pulse number input between the first step-out detection and the second step-out detection is obtained. The first torque is a torque of a magnitude incapable of rotating the rotor in the closing direction to the rotation limit position, with the valve member in contact with the valve seat. The second torque is a torque of a magnitude capable of rotating the rotor in the closing direction to the rotation limit position while compressing a coil spring, with the valve member in contact with the valve seat. Thus, the first step-out corresponds to the valve closing position, the second step-out corresponds to the rotation limit position, and the pulse number input between the first step-out detection and the second step-out detection is a pulse number for rotating the rotor from the rotation limit position to the valve closing position. In other words, this pulse number relates to the valve closing position of the rotor which can be a reference for flow control. This allows easily obtaining the position of the rotor in the electric-operated valve as a reference for flow control without measuring the flow rate of the fluid.

The configurations of electric-operated valves according to embodiments of the present invention will be described hereinbelow with reference to <FIG>. An electric-operated valve <NUM> according to an embodiment is used as a flow control valve for adjusting the flow rate of refrigerant (fluid), for example, in the refrigerating cycle of an air conditioner.

<FIG> is a front view of the electric-operated valve <NUM> according to an embodiment of the present invention. <FIG> is a front view of the valve body assembly of the electric-operated valve in <FIG>. <FIG> is a sectional view of the valve body assembly in <FIG>. <FIG> illustrates a state in which the rotor is at a rotation limit position. <FIG> are diagrams illustrating a valve stem holder provided in the valve body assembly in <FIG>. <FIG> is a perspective view of the valve stem holder, and <FIG> is a plan view of the valve stem holder. <FIG> is a plan view of the valve stem holder and the rotor of the valve body assembly illustrated in <FIG>. <FIG> schematically illustrates the magnetic poles of the rotor. <FIG> is a side view of a guide bush provided in the valve body assembly in <FIG>. <FIG> are diagrams illustrating a stopper member provided in the valve body assembly in <FIG>. <FIG> is a perspective view of the stopper member, and <FIG> is a plan view of the stopper member. <FIG> is a sectional view of a stator unit provided in the electric-operated valve in <FIG>. <FIG> are diagrams illustrating a positioning member provided in the stator unit of <FIG>. <FIG> is a perspective view of the positioning member, and <FIG> is a side view of the positioning member. <FIG> are diagrams schematically illustrating the positional relationship between the magnetic poles of the rotor and the pole teeth of the stator and the pulses input to the stepping motor in operating the electric-operated valve in <FIG>. <FIG> illustrate states when pulses P[<NUM>] to P[<NUM>] are respectively input. <FIG> illustrates a state in which the rotor is at a rotation limit position. <FIG> illustrate a state in which the rotor is at a valve closing position. <FIG> illustrates a state in which the rotor is at a valve opening position. The upper diagrams in <FIG> illustrate the positional relationship between the magnetic poles of the rotor and the pole teeth of the stator. The lower diagrams in <FIG> illustrate the pulses input to the stepping motor and the positional relationship between the magnetic poles of the rotor and the pole teeth of the stator. <FIG> and <FIG> are diagrams illustrating an example of the operation of the electric-operated valve in <FIG> in the manufacturing process. <FIG> and <FIG> illustrate the pulses input to the stepping motor and the positional relationship between the magnetic poles of the rotor and the pole teeth of the stator. <FIG> corresponds to a state in which the rotor is at the valve closing position. <FIG> corresponds to a state in which the stepping motor is out of step when the rotor is at the valve closing position. <FIG> corresponds to a state in which the stepping motor has returned from the step-out state. <FIG> corresponds to a state in which the rotor has rotated from the state in <FIG> by one pulse. <FIG> corresponds to a state in which the rotor is at a rotation limit position. <FIG> corresponds to a state in which the stepping motor is out of step when the rotor is at the rotation limit position. <FIG> is a schematic configuration diagram of an air conditioner including the electric-operated valve in <FIG>. <FIG> are diagrams illustrating the positional relationship between the internal thread of the valve stem holder and the external thread of the guide bush of the valve body assembly in <FIG>. <FIG> is a sectional view illustrating a state in which the upward-facing surface of the internal thread of the valve stem holder and the downward-facing surface of the external thread of the guide bush are in contact with each other. <FIG> is a sectional view illustrating a state in which the downward-facing surface of the internal thread of the valve stem holder and the upward-facing surface of the external thread of the guide bush are in contact with each other.

As illustrated in <FIG>, the electric-operated valve <NUM> includes a valve body assembly <NUM>, a stator unit <NUM>, and a label <NUM>.

As illustrated in <FIG> and <FIG>, the valve body assembly <NUM> includes a valve body <NUM>, a can <NUM>, a valve member <NUM>, and a driving section <NUM>.

The valve body <NUM> is made of metal, such as an aluminum alloy. The valve body <NUM> includes a body member <NUM> and a connection member <NUM>. The body member <NUM> has a columnar shape. The body member <NUM> includes a valve chamber <NUM>. A first conduit <NUM> is bonded to the outer circumferential surface of the body member <NUM>. A second conduit <NUM> is bonded to the lower end face of the body member <NUM>. The first conduit <NUM> is disposed in a direction (the lateral direction in <FIG>) perpendicular to an axis L and is connected to the valve chamber <NUM>. The second conduit <NUM> is disposed along the axis L and is connected to the valve chamber <NUM> via a valve port <NUM>. The valve port <NUM> is enclosed by a valve seat <NUM>, which has an annular shape, in the valve chamber <NUM>. A fitting hole 11a is formed in a circular shape at the upper end face of the body member <NUM>. The inner circumferential surface of the fitting hole 11a has a planar surface 11d facing the left in <FIG>. A through hole 11b communicating with the valve chamber <NUM> is formed at the bottom of the fitting hole 11a. The connection member <NUM> has an annular plate-like shape. The inner circumferential edge of the connection member <NUM> is bonded to the upper end of the body member <NUM>.

The can <NUM> is made of metal, such as stainless steel. The can <NUM> has a cylindrical shape that is open at the lower end and is closed at the upper end. The lower end of the can <NUM> is bonded to the outer peripheral edge of the connection member <NUM>.

The valve member <NUM> includes a first stem portion <NUM>, a second stem portion <NUM>, and a valve portion <NUM>. The first stem portion <NUM> has a columnar shape. The second stem portion <NUM> has a columnar shape. The diameter of the second stem portion <NUM> is smaller than the diameter of the first stem portion <NUM>. The second stem portion <NUM> is coaxially connected to the upper end of the first stem portion <NUM>. A step portion <NUM> is formed between the first stem portion <NUM> and the second stem portion <NUM>. The step portion <NUM> is an annular plane facing upward. The valve portion <NUM> has a substantially conical shape that decreases in diameter from above to bottom. The valve portion <NUM> is coaxially connected to the lower end of the first stem portion <NUM>. The tip end of the valve portion <NUM> is disposed in the valve port <NUM>. A variable throttle is formed between the valve portion <NUM> and the valve port <NUM>. The valve portion <NUM> faces the valve seat <NUM> and is in contact with the valve seat <NUM> in a valve-closing state.

The driving section <NUM> moves the valve member <NUM> in the vertical direction (in the direction of the axis L). The valve port <NUM> is opened and closed by the movement of the valve member <NUM>. The driving section <NUM> includes a rotor <NUM>, a valve stem holder <NUM>, a guide bush <NUM>, a stopper member <NUM>, and a fixed member <NUM>.

The rotor <NUM> has a cylindrical shape. The outside diameter of the rotor <NUM> is slightly smaller than the inside diameter of the can <NUM>. The rotor <NUM> is disposed inside the can <NUM> so as to be rotatable with respect to the valve body <NUM>. A plurality of north (N) poles and a plurality of south (S) poles are formed on the outer circumferential surface of the rotor <NUM>. The N poles and the S poles extend in the vertical direction. The N poles and the S poles are alternately disposed in the circumferential direction at regular angular intervals. In this embodiment, the rotor <NUM> includes <NUM> N poles and <NUM> poles. The angle between N and S poles adjacent to each other is <NUM> degrees.

<FIG> illustrate the valve stem holder <NUM>. The valve stem holder <NUM> has a cylindrical shape that is open at the lower end and is closed at the upper end. As illustrated in <FIG>, the valve stem holder <NUM> is fitted in the rotor <NUM>. The valve stem holder <NUM> rotates with the rotor <NUM>. The valve stem holder <NUM> includes a movable stopper <NUM> at the lower end. The movable stopper <NUM> is a protrusion protruding from the outer circumferential surface of the valve stem holder <NUM> outward in the radial direction. The second stem portion <NUM> of the valve member <NUM> is disposed in a stem hole 42b formed at an upper wall portion 42a of the valve stem holder <NUM> so as to be movable in the direction of the axis L. A washer <NUM> is disposed on the lower surface of the upper wall portion 42a of the valve stem holder <NUM>. A valve closing spring <NUM> is disposed between the washer <NUM> and the step portion <NUM> of the valve member <NUM>. The valve closing spring <NUM> is a coil spring, which pushes the valve member <NUM> toward the valve seat <NUM>. The inner circumferential surface of the valve stem holder <NUM> has an internal thread 42c.

<FIG> illustrates the guide bush <NUM>. The guide bush <NUM> includes a base portion 43a and a support portion 43b. The base portion 43a has a cylindrical shape. The support portion 43b has a cylindrical shape. The outer circumferential surface of the base portion 43a has a planar surface 43d. The base portion 43a is press-fitted in the fitting hole 11a of the body member <NUM>, so that the planar surface 43d comes into contact with the planar surface 11d of the fitting hole 11a. This causes the axis of the body member <NUM> and the axis of the guide bush <NUM> to align on the axis L and the guide bush <NUM> to be correctly positioned to the body member <NUM> about the axis L. The outside diameter of the support portion 43b is smaller than the outside diameter of the base portion 43a. The inside diameter of the support portion 43b is equal to the inside diameter of the base portion 43a. The support portion 43b is coaxially connected to the upper end of the base portion 43a. The outer circumferential surface of the support portion 43b has an external thread 43c. The external thread 43c is screwed in the internal thread 42c of the valve stem holder <NUM>. The first stem portion <NUM> of the valve member <NUM> is disposed in the guide bush <NUM>. The guide bush <NUM> supports the valve member <NUM> movably in the direction of the axis L.

<FIG> illustrate the stopper member <NUM>. The stopper member <NUM> includes a stopper body 44a. The stopper body 44a has a cylindrical shape. The inner circumferential surface of the stopper body 44a has an internal thread 44c. The stopper body 44a includes a fixed stopper <NUM>. The fixed stopper <NUM> is a protrusion protruding from the outer circumferential surface of the stopper body 44a outward in the radial direction. The stopper member <NUM> is fixed to the guide bush <NUM> by screwing the internal thread 44c and the external thread 43c until the stopper body 44a comes into contact with the base portion 43a of the guide bush <NUM>.

The fixed member <NUM> includes a fixed portion 45a and a flange portion 45b. The fixed portion 45a has a stepped cylindrical shape. The second stem portion <NUM> of the valve member <NUM> is disposed inside the fixed portion 45a. The fixed portion 45a is welded to the second stem portion <NUM>. The flange portion 45b is connected to the lower end of the fixed portion 45a. A return spring <NUM> is disposed around the fixed member <NUM>. The return spring <NUM> is a coil spring.

<FIG> illustrates the stator unit <NUM>. The stator unit <NUM> includes a stator <NUM>, a housing <NUM>, and a positioning member <NUM>.

The stator <NUM> has a cylindrical shape. The stator <NUM> includes an A-phase stator <NUM> and a B-phase stator <NUM>.

The A-phase stator <NUM> includes a plurality of claw-pole type pole teeth 61a and 61b around the inner circumference. The tip ends of the pole teeth 61a point down, and the tip ends of the pole teeth 61b point up. The pole teeth 61a and the pole teeth 61b are alternately disposed at regular angular intervals in the circumferential direction. In this embodiment, the A-phase stator <NUM> includes <NUM> pole teeth 61a and <NUM> pole teeth 61b. The angle between pole teeth 61a and 61b adjacent to each other is <NUM> degrees. When the coil 61c of the A-phase stator <NUM> is energized, the pole teeth 61a and the pole teeth 61b have opposite polarities.

The B-phase stator <NUM> includes a plurality of claw-pole type pole teeth 62a and 62b around the inner circumference. The tip ends of the pole teeth 62a point down, and the tip ends of the pole teeth 62b point up. The pole teeth 62a and the pole teeth 62b are alternately disposed at regular angular intervals in the circumferential direction. In this embodiment, the B-phase stator <NUM> includes <NUM> pole teeth 62a and <NUM> pole teeth 62b. The angle between pole teeth 62a and 62b adjacent to each other is <NUM> degrees. When the coil 62c of the B-phase stator <NUM> is energized, the pole teeth 62a and the pole teeth 62b have opposite polarities.

The A-phase stator <NUM> and the B-phase stator <NUM> are coaxially disposed. The A-phase stator <NUM> and the B-phase stator <NUM> are in contact with each other. When viewed in the direction of the axis L, the angle between the pole teeth 61a of the A-phase stator <NUM> and the pole teeth 62a of the B-phase stator <NUM> adjacent to each other is <NUM> degrees. The coil 61c of the A-phase stator <NUM> and the coil 62c of the B-phase stator <NUM> are connected to lead wires <NUM>.

The can <NUM> is disposed in the stator <NUM>. The stator <NUM> constitutes a stepping motor <NUM> with the rotor <NUM> disposed in the can <NUM>.

When a pulse signal is input to the coil 61c of the A-phase stator <NUM> and the coil 62c of the B-phase stator <NUM>, the rotor <NUM> of the stepping motor <NUM> rotates. Pulses P[<NUM>] to P[<NUM>] illustrated in <FIG> are input to the stepping motor <NUM> in order. The expression "inputting a pulse to the stepping motor <NUM>" in this specification is synonymous with "supplying a drive current according to the pulse to the stator <NUM> (coils 61c and 62c) of the stepping motor <NUM>". In <FIG>, the reference pole tooth 61a and the reference magnetic pole (S pole) of the rotor <NUM> are marked with a black circle for easy understanding of the positional relationship between the rotor <NUM> and the stator <NUM> (the A-phase stator <NUM> and the B-phase stator <NUM>).

In rotating the rotor <NUM> in the closing direction (clockwise in <FIG>), pulses P are cyclically input to the stepping motor <NUM> in descending order (in the order from pulse P[<NUM>] to pulse P[<NUM>]). When the rotor <NUM> is rotated in the closing direction, the rotor <NUM> and the valve stem holder <NUM> moves downward by the screw feed action of the internal thread 42c of the valve stem holder <NUM> and the external thread 43c of the guide bush <NUM>. The valve stem holder <NUM> pushes the valve member <NUM> downward via the valve closing spring <NUM>. The valve member <NUM> moves downward to bring the valve portion <NUM> into contact with the valve seat <NUM>. The position of the rotor <NUM> at that time is a valve closing position Rc (<FIG>). When the rotor <NUM> is further rotated from this state in the closing direction, the valve closing spring <NUM> is compressed to further move the rotor <NUM> and the valve stem holder <NUM> downward. The valve member <NUM> is not moved downward. When the movable stopper <NUM> of the valve stem holder <NUM> and the fixed stopper <NUM> of the stopper member <NUM> come into contact with each other, the rotation of the rotor <NUM> in the closing direction is limited. The position of the rotor <NUM> at this time is a rotation limit position Rx (<FIG>).

In rotating the rotor <NUM> in the opening direction (counterclockwise in <FIG>) opposite to the closing direction, pulses P are cyclically input to the stepping motor <NUM> in ascending order (in the order from pulse P[<NUM>] to pulse P[<NUM>]). When the rotor <NUM> is rotated in the opening direction, the rotor <NUM> and the valve stem holder <NUM> moves upward by the screw feed action of the internal thread 42c of the valve stem holder <NUM> and the external thread 43c of the guide bush <NUM>. The valve stem holder <NUM> pushes the fixed member <NUM> upward. The valve member <NUM> moves upward with the fixed member <NUM> to separate the valve member <NUM> from the valve seat <NUM>. The position of the rotor <NUM> at which the fluid flow rate at the valve port <NUM> (the degree of opening of the valve port <NUM>) in a predetermined flow-rate measuring environment is a predetermined set value is referred to as a valve opening position Ro (<FIG>). The set value is set as appropriate according to the configuration and application of the electric-operated valve <NUM>.

The housing <NUM> is made of synthetic resin. The housing <NUM> is injection molded. The housing <NUM> houses the stator <NUM>. The housing <NUM> includes a peripheral wall portion <NUM> and an upper wall portion <NUM>.

The peripheral wall portion <NUM> has a cylindrical shape. The stator <NUM> is embedded inside the peripheral wall portion <NUM>. The diameter of a space defined by the inner circumferential surface 71a of the peripheral wall portion <NUM> is equal to the diameter of a space defined by the stator inner circumferential surface 60a. The inner circumferential surface 71a connects to the stator inner circumferential surface 60a without level difference. The upper wall portion <NUM> is connected to the upper end of the peripheral wall portion <NUM>. The inner circumferential surface 71a of the peripheral wall portion <NUM>, the inner surface 72a of the upper wall portion <NUM>, and the stator inner circumferential surface 60a form the inner space <NUM> of the stator unit <NUM>. The can <NUM> is disposed in the inner space <NUM>.

A positioning member <NUM> is fixed to the housing <NUM>. The positioning member <NUM> is made of metal. <FIG> illustrate the positioning member <NUM>. The positioning member <NUM> includes a flat plate portion 77a and two arm portions 77b. The flat plate portion 77a has a rectangular shape. The flat plate portion 77a is fixed to the lower end of the housing <NUM>. The arm portions 77b have a corrugated plate shape. The arm portions 77b extend downward from the sides of the flat plate portion 77a opposing in the width direction (the lateral direction in <FIG>). The arm portions 77b are elastically deformable in the width direction of the flat plate portion 77a. The two arm portions 77b hold the first conduit <NUM>. This allows the stator unit <NUM> to be positioned with respect to the valve body <NUM>.

The label <NUM> is affixed to the outer circumferential surface of the body member <NUM>. The label <NUM> is printed with valve opening point information J. The valve opening point information J contains valve opening point Nk and origin pulse pattern number PTx. The valve opening point Nk is the number of pulses (hereinafter referred to as "pulse number") input to the stepping motor <NUM> to rotate the rotor <NUM> from the rotation limit position Rx to the valve opening position Ro. The origin pulse pattern number PTx is used in an operation for positioning the rotor <NUM> in the electric-operated valve <NUM> to the rotation limit position Rx (a home positioning operation). The valve opening point information J is printed on the label <NUM>, for example, in a two-dimensional code format. The valve opening point information J may be printed in a format other than the two-dimensional code format. The valve opening point information J may be printed directly on the outer circumferential surface of the body member <NUM> or impressed by laser light. Alternatively, the label <NUM> may be affixed to the outer surface of the housing <NUM>. Alternatively, a radio-frequency (RF) tag on which valve opening point information J is recorded may be used in place of the label <NUM> on which valve opening point information J is printed. In other words, the valve opening point information J should only be recorded on the electric-operated valve <NUM> in a format readable by a device that controls the electric-operated valve <NUM>.

In the electric-operated valve <NUM>, the respective central axes of the valve port <NUM>, the can <NUM>, the valve member <NUM>, the rotor <NUM>, the valve stem holder <NUM>, the guide bush <NUM>, the stator <NUM> (the A-phase stator <NUM> and the B-phase stator <NUM>) are aligned with the axis L.

Next, an example of a method of manufacturing the electric-operated valve <NUM> will be described.

Before manufacturing the electric-operated valve <NUM>, the number of pulses (common pulse number Ni) to be input to the stepping motor <NUM> to rotate the rotor <NUM> from the valve closing position Rc to the valve opening position Ro is obtained using a reference electric-operated valve <NUM> with the same configuration as that of the electric-operated valve <NUM> and having high component accuracy and assembly accuracy. The valve closing position Rc and the valve opening position Ro may be the same (that is, common pulse number Ni = <NUM>). The respective common pulse numbers Ni of a plurality of electric-operated valves <NUM> whose component accuracy and assembly accuracy are within a tolerance range have the same value.

The valve body assembly <NUM> and the stator unit <NUM> are produced, and the can <NUM> of the valve body assembly <NUM> is inserted into the inner space <NUM> of the stator unit <NUM>. The first conduit <NUM> is held by the two arm portions 77b of the positioning member <NUM>, and the stator unit <NUM> is positioned with respect to the valve body <NUM>. Thus, the electric-operated valve <NUM> on which the label <NUM> is not affixed is obtained.

Next, the label <NUM> is produced. The valve opening point Nk and the origin pulse pattern number PTx of the electric-operated valve <NUM> are obtained to obtain the valve opening point information J to be printed to the label <NUM> using an inspection device (not shown) for factory shipment. The inspection device includes a computer and a memory.

The inspection device can input pulse signals (pulses P[<NUM>] to P[<NUM>]) to the stepping motor <NUM>. The inspection device can change the torque of the stepping motor <NUM>. The inspection device can detect the step-out of the stepping motor <NUM> on the basis of the value of current flowing through the stepping motor <NUM>.

The lead wires <NUM> of the electric-operated valve <NUM> are connected to the inspection device. The inspection device inputs a sufficient number (for example, <NUM>) of pulses P for the valve member <NUM> (the valve portion <NUM>) to come away from the valve seat <NUM> to the stepping motor <NUM> of the electric-operated valve <NUM> cyclically in ascending order to rotate the rotor <NUM> in the opening direction. This causes the valve member <NUM> to come away from the valve seat <NUM>.

Next, the inspection device sets a torque for rotating the rotor <NUM> to a first torque T1. The first torque T1 is a torque of a magnitude that cannot rotate the rotor <NUM> in the closing direction to the rotation limit position Rx, with the valve member <NUM> in contact with the valve seat <NUM>. The magnitude of the first torque T1 is relatively small. The inspection device inputs the pulses P to the stepping motor <NUM> of the electric-operated valve <NUM> cyclically in descending order to rotate the rotor <NUM> in the closing direction with the first torque T1. The inspection device monitors the step-out of the stepping motor <NUM>.

When the rotor <NUM> rotates in the closing direction, the valve member <NUM> moves toward the valve seat <NUM>. The valve member <NUM> is brought into contact with the valve seat <NUM> in response to a pulse P (for example, pulse P[<NUM>] in <FIG>) input at a certain point in time. At that time, the rotor <NUM> is at the valve closing position Rc. The inspection device further inputs one pulse P (for example, pulse P[<NUM>] in <FIG>), with the valve member <NUM> in contact with the valve seat <NUM>. Since the inspection device sets the torque for rotating the rotor <NUM> to the first torque T1, the inspection device cannot rotate the rotor <NUM> in the closing direction. This causes the step-out of the stepping motor <NUM>, and the inspection device detects the first step-out of the stepping motor <NUM> (first step-out detection). The inspection device stores a pulse pattern number PT1 (for example, [<NUM>]) of the pulse P corresponding to the first step-out detection in the memory.

After the first step-out detection, the inspection device sets the torque for rotating the rotor <NUM> to a second torque T2. The second torque T2 is a torque of a magnitude that can rotate the rotor <NUM> in the closing direction to the rotation limit position Rx while compressing the valve closing spring <NUM>, with the valve member <NUM> in contact with the valve seat <NUM>. The second torque T2 may be a torque used in the normal operation (flow-rate control operation) of the electric-operated valve <NUM>. The inspection device inputs a pulse P (for example, pulse P[<NUM>] in <FIG>) with the pulse pattern number PT1 stored in the memory at the first step-out detection to the stepping motor <NUM> of the electric-operated valve <NUM>. Since the inspection device sets the torque for rotating the rotor <NUM> to the second torque T2, the inspection device can rotate the rotor <NUM> in the closing direction while the valve closing spring <NUM> is being compressed. This allows the stepping motor <NUM> to be returned from the step-out state to the normal state.

The inspection device inputs a pulse P to the stepping motor <NUM> of the electric-operated valve <NUM> cyclically in descending order (for example, from pulse P[<NUM>] in <FIG>) to further rotate the rotor <NUM> in the closing direction with the second torque T2.

When the rotor <NUM> rotates in the closing direction, the valve closing spring <NUM> is gradually compressed with the valve member <NUM> not moving in contact with the valve seat <NUM>. The movable stopper <NUM> is brought into contact with the fixed stopper <NUM> in response to a pulse P (for example, pulse P[<NUM>] in <FIG>) input at a certain point in time. At that time, the rotor <NUM> is at the rotation limit position Rx. The inspection device further inputs one pulse P (for example, pulse P[<NUM>] in <FIG>), with the movable stopper <NUM> in contact with the fixed stopper <NUM>. Since the rotor <NUM> is at the rotation limit position Rx, the inspection device cannot rotate the rotor <NUM> in the closing direction. This causes the step-out of the stepping motor <NUM>, and the inspection device detects the second step-out of the stepping motor <NUM> (second step-out detection).

The inspection device counts the number of pulses (a unique pulse number Nj) input to the stepping motor <NUM> between the first step-out detection and the second step-out detection (specifically, during the interval after the first step-out detection before the second step-out detection) and stores the unique pulse number Nj in the memory. The inspection device stores the pulse pattern number PT2 (for example, [<NUM>] in <FIG>) of the pulse P input immediately before the pulse P corresponding to the second step-out detection in the memory.

The inspection device adds up the common pulse number Ni and the unique pulse number Nj to obtain a valve opening point Nk (Nk = Nj + Ni), and sets the pulse pattern number PT2 as origin pulse pattern number PTx. The valve opening point Nk is information on the unique pulse number Nj. The inspection device prepares the label <NUM> on which the valve opening point information J containing the valve opening point Nk and the origin pulse pattern number PTx is printed with a label printer (not shown). The inspection device affixes the label <NUM> to the outer circumferential surface of the body member <NUM> with a label attaching machine (not shown) to complete the electric-operated valve <NUM>. In place of the valve opening point Nk, the inspection device may contain the unique pulse number Nj in the valve opening point information J.

Next, an air conditioner <NUM> including the electric-operated valve <NUM> will be described. The electric-operated valve <NUM> is applicable to both of home air conditioners and in-car air conditioners.

<FIG> illustrates the air conditioner <NUM>. The air conditioner <NUM> performs a cooling operation and a heating operation. <FIG> schematically illustrates the flow of a refrigerant in the cooling operation using the solid arrows and the flow of a refrigerant in the heating operation with the dashed arrows. In the cooling operation of the air conditioner <NUM>, the refrigerant flows from a compressor <NUM>, a flow-channel switching valve <NUM>, an outdoor heat exchanger <NUM>, the electric-operated valve <NUM>, an indoor heat exchanger <NUM>, and the flow-channel switching valve <NUM> in order and returns to the compressor <NUM>. In the heating operation of the air conditioner <NUM>, the refrigerant flows from the compressor <NUM>, the flow-channel switching valve <NUM>, the indoor heat exchanger <NUM>, the electric-operated valve <NUM>, the outdoor heat exchanger <NUM>, and the flow-channel switching valve <NUM> in order and returns to the compressor <NUM>. The electric-operated valve <NUM> is used as a flow control valve in the air conditioner <NUM>.

The air conditioner <NUM> further includes an electronic control unit <NUM> that controls the compressor <NUM>, the electric-operated valve <NUM>, and so on. The electronic control unit <NUM> includes, for example, a microcomputer including a nonvolatile memory. The electronic control unit <NUM> controls the flow rate of the refrigerant at the valve port <NUM> (the degree of opening of the valve port <NUM>) of the electric-operated valve <NUM> in the cooling operation and the heating operation. The electronic control unit <NUM> rotates the rotor <NUM> with the second torque T2.

The electric-operated valve <NUM> installed in the air conditioner <NUM> may vary in the valve opening point Nk according to the component accuracy or the assembly accuracy. The electronic control unit <NUM> can perform accurate flow control of the electric-operated valve <NUM> by using the valve opening point information J read from the label <NUM> of the electric-operated valve <NUM>.

The nonvolatile memory of the electronic control unit <NUM> stores the valve opening point information J on the electric-operated valve <NUM> read with a two-dimensional code reader in the manufacturing process of the air conditioner <NUM>.

Upon starting the electric-operated valve <NUM>, the electronic control unit <NUM> executes a home positioning operation. In the home positioning operation, the electronic control unit <NUM> inputs a sufficient number of pulses P to bring the movable stopper <NUM> into contact with the fixed stopper <NUM> to the stepping motor <NUM> cyclically in descending order to rotate the rotor <NUM> in the closing direction. The electronic control unit <NUM> lastly inputs a pulse P (for example, pulse P[<NUM>]) with the origin pulse pattern number PTx in the valve opening point information J, then stops the input of the pulses P. Thus, the rotor <NUM> is positioned at the rotation limit position Rx.

Next, the electronic control unit <NUM> inputs pulses P to the stepping motor <NUM> cyclically in ascending order to rotate the rotor <NUM> in the opening direction. At that time, the electronic control unit <NUM> starts the input from a pulse P (for example, pulse P[<NUM>]) with a pulse pattern number one greater than the origin pulse pattern number PTx. In this embodiment, a pulse pattern number one greater than [<NUM>] is [<NUM>]. When the number of pulses input in ascending order reaches the valve opening point Nk, the electronic control unit <NUM> stops the input of the pulses P. Thus, the rotor <NUM> is positioned at the valve opening position Ro, and the home positioning operation is completed.

As described above, the electric-operated valve <NUM> according to this embodiment includes the valve body <NUM> including the valve seat <NUM>, the rotor <NUM> rotatable with respect to the valve body <NUM>, the stator <NUM> constituting the stepping motor <NUM> together with the rotor <NUM>, the valve member <NUM> that faces the valve seat <NUM> and that is pushed toward the valve seat <NUM> via the valve closing spring <NUM> when the rotor <NUM> rotates in a closing direction, and the movable stopper <NUM> and the fixed stopper <NUM> that, when the rotor <NUM> is at the rotation limit position Rx where the rotor <NUM> is further rotated in the closing direction from the valve closing position Rc where the valve member <NUM> is in contact with the valve seat <NUM>, limit rotation of the rotor <NUM> in the closing direction.

The inspection device, in a process for manufacturing the electric-operated valve <NUM>,.

Thus, the first step-out corresponds to the valve closing position Rc, the second step-out corresponds to the rotation limit position Rx, and the number of pulses input between the first step-out detection and the second step-out detection is taken as the unique pulse number Nj for rotating the rotor <NUM> from the rotation limit position Rx to the valve closing position Rc. The unique pulse number Nj is related to the valve closing position Rc of the rotor <NUM>. The valve opening point Nk calculated using the unique pulse number Nj is related to the valve opening position Ro as a reference for flow control. This allows easily obtaining the position of the rotor <NUM> in the electric-operated valve <NUM> as a reference for flow control without measuring the flow rate of the fluid.

The electric-operated valve <NUM> takes the position of the rotor <NUM> at the point in time the valve member <NUM> comes into contact with the valve seat <NUM> as the valve closing position Rc and detects the step-out of the stepping motor <NUM> when one pulse P is further input, with the rotor <NUM> at the valve closing position Rc. However, depending on the configuration of the electric-operated valve <NUM>, the first step-out of the stepping motor <NUM> may be detected when a plurality of pulses P (about <NUM> to <NUM> pulses P) are input with the rotor <NUM> at the position when the valve member <NUM> comes into contact with the valve seat <NUM>. In this case, a common pulse number Ni is set to a number containing the number of pulses input to the stepping motor <NUM> from the point in time the valve member <NUM> comes into contact with the valve seat <NUM> until the first step-out is detected.

The common pulse number Ni will be specifically described.

In this embodiment, the position of the rotor <NUM> when the rotor <NUM> is rotated in the closing direction with the first torque T1 to bring the valve member <NUM> into contact with the valve seat <NUM> is taken as the valve closing position Rc. When the rotor <NUM> is at the valve closing position Rc, the first step-out of the stepping motor <NUM> occurs. Actually, the specifications of the valve closing spring <NUM> and the first torque T1 may be set for the electric-operated valve <NUM> so that, when the rotor <NUM> is at a position (hereinafter referred to as "contact position Rt") at the point in time the valve member <NUM> comes into contact with the valve seat <NUM>, the valve closing spring <NUM> is in a state immediately before being compressed, and when the rotor <NUM> rotates from the contact position Rt in the closing direction to slightly compress the valve closing spring <NUM>, the first step-out of the stepping motor <NUM> occurs. In other words, the first torque T1 is set so that the downward load applied to the valve stem holder <NUM> by rotation of the rotor <NUM> with the first torque T1 and the upward load applied to the valve stem holder <NUM> by the valve closing spring <NUM> are balanced before the rotor <NUM> passes through the contact position Rt to reach the rotation limit position Rx, and the first torque T1 is a torque of a magnitude that cannot rotate the rotor <NUM> in the closing direction to the rotation limit position Rx, with the valve member <NUM> in contact with the valve seat <NUM>. In this case, when the rotor <NUM> is positioned between the contact position Rt and the rotation limit position Rx, the first step-out of the stepping motor <NUM> occurs, and the position of the rotor <NUM> at the first step-out is detected as the valve closing position Rc. This position is also referred to as a step-out detection position Rd. When the rotor <NUM> is at the step-out detection position Rd, the upward load (spring load) applied to the valve stem holder <NUM> by the valve closing spring <NUM> is received by the guide bush <NUM> to cause the upward-facing surface of the internal thread 42c to push the downward-facing surface of the external thread 43c (<FIG>).

In the electric-operated valve <NUM>, when the rotor <NUM> rotates from the step-out detection position Rd in the opening direction to reach the contact position Rt, the valve closing spring <NUM> is decompressed to eliminate the spring load to bring a state in which the upward-facing surface of the internal thread 42c is in slight-contact with the downward-facing surface of the external thread 43c (or a state in which there is a slight gap therebetween). At that time, a load (differential pressure load) generated by the differential pressure between the refrigerant pressure in the valve chamber <NUM> and the refrigerant pressure in the valve port <NUM> may be applied to the valve member <NUM> to make the valve member <NUM> kept contact with the valve seat <NUM> depending on the direction and magnitude of the differential pressure load. When the rotor <NUM> rotates from the contact position Rt in the opening direction, the downward-facing surface of the internal thread 42c and the upward-facing surface of the external thread 43c come into contact with each other by the gravity and the differential pressure load acting on the valve member <NUM>, the rotor <NUM>, and the valve stem holder <NUM> (<FIG>). This state is immediately before the valve member <NUM> comes away from the valve seat <NUM>, and a position of the rotor <NUM> in this state may be taken as the valve opening position Ro. Alternatively, the rotor <NUM> is further rotated in the opening direction in this state, and the position of the rotor when the valve member <NUM> comes away from the valve seat <NUM> may be taken as the valve opening position Ro.

In other words, the common pulse number Ni may include (<NUM>) the number of pulses input to the stepping motor <NUM> to rotate the rotor <NUM> from the step-out detection position Rd to the contact position Rt and (<NUM>) the number of pulses input to the stepping motor <NUM> to rotate the rotor <NUM> from a position where the upward-facing surface of the internal thread 42c and the downward-facing surface of the external thread 43c are in contact with each other to a position where the downward-facing surface of the internal thread 42c and the upward-facing surface of the external thread 43c are in contact with each other (that is, a pulse number corresponding to the allowance between the internal thread 42c and the external thread 43c). The common pulse number Ni, the first torque T1, and the second torque T2 also apply to electric-operated valves 1A and 1B described later.

The electric-operated valve <NUM> described above detects the step-out of the stepping motor <NUM> when one pulse P is further input, with the rotor <NUM> at the rotation limit position Rx. However, depending on the configuration of the electric-operated valve <NUM>, the second step-out of the stepping motor <NUM> may be detected when a plurality of pulses P (about <NUM> or <NUM> pulses P) are input, with the rotor <NUM> at the rotation limit position Rx. In this case, the number of pulses (correcting pulse number) to be input to the stepping motor <NUM> from the point in time the rotor <NUM> reaches the rotation limit position Rx until the second step-out is detected is obtained in advance using the reference electric-operated valve <NUM>. Then, the inspection device corrects the number of pulses input between the first step-out detection and the second step-out detection to a pulse number for rotating the rotor <NUM> from the rotation limit position Rx to the valve closing position Rc using the correcting pulse number obtained using the reference electric-operated valve <NUM> to obtain the unique pulse number Nj.

The electric-operated valve <NUM> described above is directly controlled by the electronic control unit <NUM> that is an upper-level device. In addition, the present invention is also applicable to an electric-operated valve including a control unit that rotates the stepping motor <NUM> on the basis of a command received from an upper-level device, like the electric-operated valves 1A and 1B described below.

The electric-operated valve 1A including the control unit will be described hereinbelow.

The electric-operated valve 1A has the same (including substantially the same) configuration as that of the electric-operated valve <NUM> except that the electric-operated valve 1A includes the control unit (not shown). The control unit is installed in the stator unit <NUM>.

The control unit includes a microcomputer. An example of the microcomputer is a microcomputer in which a central processing unit, a nonvolatile memory, a working memory, a communication module, a motor driver, and so on are integrated in one package.

The control unit can input pulse signals (pulses P[<NUM>] to P[<NUM>]) to the stepping motor <NUM>. The control unit can change the torque of the stepping motor <NUM>. The control unit can detect the step-out of the stepping motor <NUM> on the basis of the value of current flowing through the stepping motor <NUM>. The nonvolatile memory of the control unit stores the common pulse number Ni.

Upon receiving an initialization command from an upper-level device, the control unit executes an initialization operation. In the initialization operation, the control unit executes the same (including substantially the same) operation as the operation for obtaining the valve opening point information J in the inspection device described above.

In the initialization operation, the control unit inputs a sufficient number (for example, <NUM>) of pulses P for the valve member <NUM> (the valve portion <NUM>) to come away from the valve seat <NUM> to the stepping motor <NUM> cyclically in ascending order to rotate the rotor <NUM> in the opening direction. This causes the valve member <NUM> to come away from the valve seat <NUM>.

Next, the control unit sets a torque for rotating the rotor <NUM> to the first torque T1. The control unit inputs the pulses P to the stepping motor <NUM> cyclically in descending order to rotate the rotor <NUM> in the closing direction with the first torque T1. The control unit monitors the step-out of the stepping motor <NUM>.

When the rotor <NUM> rotates in the closing direction, the valve member <NUM> moves toward the valve seat <NUM>. The valve member <NUM> is brought into contact with the valve seat <NUM> in response to a pulse P (for example, pulse P[<NUM>]) input at a certain point in time. At that time, the rotor <NUM> is at the valve closing position Rc. The control unit further inputs one pulse P (for example, pulse P[<NUM>]), with the valve member <NUM> in contact with the valve seat <NUM>. Since the control unit sets the torque for rotating the rotor <NUM> to the first torque T1, the control unit cannot rotate the rotor <NUM> in the closing direction. This causes the step-out of the stepping motor <NUM>, and the control unit detects the first step-out of the stepping motor <NUM> (first step-out detection). The control unit stores the pulse pattern number PT1 (for example, [<NUM>]) of the pulse P corresponding to the first step-out detection in a working memory.

After the first step-out detection, the control unit sets the torque for rotating the rotor <NUM> to the second torque T2. The control unit inputs a pulse P (for example, pulse P[<NUM>]) with the pulse pattern number PT1 stored in the working memory at the first step-out detection to the stepping motor <NUM>. Since the control unit sets the torque for rotating the rotor <NUM> to the second torque T2, the control unit can rotate the rotor <NUM> in the closing direction while compressing the valve closing spring <NUM>. This allows the stepping motor <NUM> to be returned from the step-out state to a normal state.

The control unit inputs pulses P to the stepping motor <NUM> cyclically in descending order to further rotate the rotor <NUM> in the closing direction with the second torque T2.

When the rotor <NUM> rotates in the closing direction, the valve closing spring <NUM> is gradually compressed with the valve member <NUM> not moving in contact with the valve seat <NUM>. The movable stopper <NUM> is brought into contact with the fixed stopper <NUM> in response to a pulse P (for example, pulse P[<NUM>]) input at a certain point in time. At that time, the rotor <NUM> is at the rotation limit position Rx. The control unit further input one pulse P (for example, pulse P[<NUM>]), with the movable stopper <NUM> in contact with the fixed stopper <NUM>. Since the rotor <NUM> is at the rotation limit position Rx, the control unit cannot rotate the rotor <NUM> in the closing direction. This causes the step-out of the stepping motor <NUM>, and the control unit detects the second step-out of the stepping motor <NUM> (second step-out detection).

The control unit counts the number of pulses (a unique pulse number Nj) input to the stepping motor <NUM> between the first step-out detection and the second step-out detection (specifically, during the interval after the first step-out detection before the second step-out detection) and stores the unique pulse number Nj in the working memory. The control unit stores the pulse pattern number PT2 (for example, [<NUM>]) of the pulse P input immediately before the pulse P corresponding to the second step-out detection in the working memory. The control unit inputs the pulse P (for example, pulse P[<NUM>]) with the pulse pattern number PT2 to the stepping motor <NUM>. This allows the stepping motor <NUM> to be returned from the step-out state to the normal state to position the rotor <NUM> at the rotation limit position Rx.

The control unit adds up the common pulse number Ni and the unique pulse number Nj to calculate the valve opening point Nk (Nk = Nj + Ni) and stores the valve opening point Nk in the working memory. The control unit may store the valve opening point Nk and the pulse pattern number PT2 in the nonvolatile memory. The valve opening point Nk and the pulse pattern number PT2 (that is, the origin pulse pattern number PTx) are used in a home positioning operation.

The control unit inputs the pulses P to the stepping motor <NUM> cyclically in ascending order to rotate the rotor <NUM> in the opening direction. At this time, the control unit starts inputting from a pulse P (for example pulse P[<NUM>]) with a pulse pattern number one greater than the pulse pattern number PT2. When the number of pulses input in ascending order reaches the valve opening point Nk, the control unit stops the input of the pulses P. Thus, the rotor <NUM> is positioned at the valve opening position Ro, and the initialization operation of the electric-operated valve 1A is completed.

The control unit of the electric-operated valve 1A, in an initialization operation,.

Thus, the first step-out corresponds to the valve closing position Rc, the second step-out corresponds to the rotation limit position Rx, and the number of pulses input between the first step-out detection and the second step-out detection is taken as the unique pulse number Nj for rotating the rotor <NUM> from the rotation limit position Rx to the valve closing position Rc. The unique pulse number Nj is related to the valve closing position Rc of the rotor <NUM>. The valve opening point Nk calculated using the unique pulse number Nj is related to the valve opening position Ro as a reference for flow control. This allows easily obtaining the position of the rotor <NUM> in the electric-operated valve 1A as a reference for flow control without measuring the flow rate of the fluid.

The control unit of the electric-operated valve 1A corrects the number of pulses input to the stepping motor <NUM> between the first step-out detection and the second step-out detection to a pulse number for rotating the rotor <NUM> from the rotation limit position Rx to the valve closing position Rc using the correcting pulse number obtained using the reference electric-operated valve <NUM> to obtain the unique pulse number Nj as needed, as the inspection device described above does.

The electric-operated valve 1B including the control unit will be described hereinbelow.

The electric-operated valve 1B has the same (including substantially the same) hardware configuration as that of the electric-operated valve 1A. The control unit executes an initializing process using the common pulse number Ni stored in the nonvolatile memory as the valve opening point Nk.

Upon receiving an initialization command from an upper-level device, the control unit executes an initialization operation.

In an initialization operation not representing the present invention, the control unit inputs a sufficient number (for example, <NUM>) of pulses P for the valve member <NUM> (the valve portion <NUM>) to come away from the valve seat <NUM> to the stepping motor <NUM> cyclically in ascending order to rotate the rotor <NUM> in the opening direction. This causes the valve member <NUM> to come away from the valve seat <NUM>.

When the rotor <NUM> rotates in the closing direction, the valve member <NUM> moves toward the valve seat <NUM>. The valve member <NUM> is brought into contact with the valve seat <NUM> in response to a pulse P (for example, pulse P[<NUM>]) input at a certain point in time. At that time, the rotor <NUM> is at the valve closing position Rc. The control unit further inputs one pulse P (for example, pulse P[<NUM>]), with the valve member <NUM> in contact with the valve seat <NUM>. Since the control unit sets the torque for rotating the rotor <NUM> to the first torque T1, the control unit cannot rotate the rotor <NUM> in the closing direction. This causes the step-out of the stepping motor <NUM>, and the control unit detects the step-out of the stepping motor <NUM>.

The control unit stores the pulse pattern number PT1 (for example, [<NUM>]) of the pulse P input immediately before the pulse P corresponding to the step-out detection in the working memory. The control unit inputs the pulse P (for example, pulse P[<NUM>]) with the pulse pattern number PT1 to the stepping motor <NUM>. This causes the stepping motor <NUM> to be returned from the step-out state to the normal state to position the rotor <NUM> at the valve closing position Rc. In other words, control unit obtains the valve closing position Rc on the basis of the step-out detection.

The control unit inputs the pulses P to the stepping motor <NUM> cyclically in ascending order to rotate the rotor <NUM> in the opening direction. At this time, the control unit starts inputting from a pulse P (for example pulse P[<NUM>]) with a pulse pattern number one greater than the pulse pattern number PT1. When the number of pulses input in ascending order reaches the common pulse number Ni, the control unit stops the input of the pulses P. Thus, the rotor <NUM> is positioned at the valve opening position Ro, and the initialization operation of the electric-operated valve 1B is completed.

The control unit of the electric-operated valve 1B, in an initialization operation not representing the present invention,.

This allows the control unit to obtain the valve closing position Rc of the rotor <NUM> by detecting step-out. The valve closing position Rc is the position of the rotor <NUM> as a reference of flow control of the electric-operated valve 1B. This allows easily obtaining the position of the rotor <NUM> in the electric-operated valve 1B as a reference for flow control without measuring the flow rate of the fluid.

According to an example not representing the present invention, the electric-operated valve 1B does not have to include the stopper member <NUM> and the fixed stopper <NUM> of the valve stem holder <NUM>. In this configuration, the first torque T1 is set so that the downward load applied to the valve stem holder <NUM> (rotor <NUM>) by rotation of the rotor <NUM> with the first torque T1 and the upward load applied to the valve stem holder <NUM> by the valve closing spring <NUM> are balanced before the valve closing spring <NUM> is compressed to the maximum extent. The first torque T1 is a torque of a magnitude that cannot rotate the rotor <NUM> in the closing direction until the valve closing spring <NUM> is compressed to the maximum extent, with the valve member <NUM> in contact with the valve seat <NUM>. The electric-operated valve 1B may have a configuration in which the valve closing spring <NUM> is omitted and the valve stem holder <NUM> directly pushes the valve member <NUM> downward. With this configuration, the position of the rotor <NUM> at the point in time the valve member <NUM> comes into contact with the valve seat <NUM> is the valve closing position Rc and the rotation limit position Rx. In this case, the first torque T1 is a torque of a magnitude that cannot rotate the rotor <NUM> in the closing direction, with the valve member <NUM> in contact with the valve seat <NUM>.

The control unit of the electric-operated valve 1A detects the step-out of the stepping motor <NUM> on the basis of the value of current flowing through the stepping motor <NUM>. Alternatively, the electric-operated valve 1A may include a permanent magnet that rotates with the rotor <NUM> and a magnetic sensor that detects the direction (rotational angle) of the magnetic field of the permanent magnet, and the control unit may detect the step-out by obtaining the rotation angle of the rotor <NUM> on the basis of the signal from the magnetic sensor. This is the same for the electric-operated valve 1B as for the electric-operated valve 1A.

In the air conditioner <NUM> including the electric-operated valve <NUM>, the electronic control unit <NUM> may perform the same (including substantially the same) operation as that of the control unit of the electric-operated valve 1A or the control unit of the electric-operated valve 1B.

In other words, the electronic control unit <NUM>, in an initialization operation for the electric-operated valve <NUM>,.

The electronic control unit <NUM> calculates a valve opening point Nk using the unique pulse number Nj and stores the valve opening point Nk in a nonvolatile memory. The electronic control unit <NUM> performs flow control using the valve opening point Nk.

Alternatively, the electronic control unit <NUM>, in an initialization operation not representing the present invention,.

The electronic control unit <NUM> calculate a valve opening point Nk using the valve closing position Rc and stores the valve opening point Nk in a nonvolatile memory. The electronic control unit <NUM> performs flow control using the valve opening point Nk.

In this specification, the terms indicating shapes, such as "cylindrical" and "columnar", are also used for components and members substantially having the shapes indicated by the terms. For example, "a cylindrical member" includes a cylindrical member and a substantially cylindrical member. the control unit may detect the step-out by obtaining the rotation angle of the rotor <NUM> on the basis of the signal from the magnetic sensor. This is the same for the electric-operated valve 1B as for the electric-operated valve 1A.

Alternatively, the electronic control unit <NUM>, in an initialization operation,.

In this specification, the terms indicating shapes, such as "cylindrical" and "columnar", are also used for components and members substantially having the shapes indicated by the terms. For example, "a cylindrical member" includes a cylindrical member and a substantially cylindrical member.

Claim 1:
An electric-operated valve (<NUM>) comprising:
a valve body (<NUM>) including a valve seat (<NUM>);
a rotor (<NUM>) rotatable with respect to the valve body (<NUM>);
a stator (<NUM>) constituting a stepping motor (<NUM>) together with the rotor (<NUM>);
a valve member (<NUM>) that faces the valve seat (<NUM>) and that is pushed toward the valve seat (<NUM>) via a coil spring (<NUM>) when the rotor (<NUM>) rotates in a closing direction;
a stopper (<NUM>) that, when the rotor (<NUM>) is at a rotation limit position (Rx) where the rotor (<NUM>) is further rotated in the closing direction from a valve closing position (Rc) where the valve member (<NUM>) is in contact with the valve seat (<NUM>), limits rotation of the rotor (<NUM>) in the closing direction; and
a control unit (<NUM>),
wherein the control unit (<NUM>) is configured to
(i) input a pulse (P) to the stepping motor (<NUM>) to rotate the rotor (<NUM>) in the closing direction with a first torque (T1),
(ii) upon detecting step-out of the stepping motor (<NUM>) when rotating the rotor (<NUM>) with the first torque (T1) (hereinafter referred to as "first step-out detection"), input the pulse (P) to the stepping motor (<NUM>) to rotate the rotor (<NUM>) in the closing direction with a second torque (T2), and
(iii) upon detecting step-out of the stepping motor (<NUM>) when rotating the rotor (<NUM>) with the second torque (T2) (hereinafter referred to as "second step-out detection"), obtain the number of pulses (a pulse number) (Nj) input between the first step-out detection and the second step-out detection,
wherein the first torque (T1) is a torque of a magnitude incapable of rotating the rotor (<NUM>) in the closing direction to the rotation limit position (Rx), with the valve member (<NUM>) in contact with the valve seat (<NUM>), and
wherein the second torque (T2) is a torque of a magnitude capable of rotating the rotor (<NUM>) in the closing direction to the rotation limit position (Rx) while compressing the coil spring (<NUM>), with the valve member (<NUM>) in contact with the valve seat (<NUM>).