Rotational position detection device for stepping motors

Abstract

This stepping-motor rotational position detection device (1) is used for a stepping motor (60) equipped with a rotor (30) that has a plurality of magnets (33, 33S, 33N) arranged in an annular shape, and detects a rotational position of the rotor. The rotational position detection device (1) has a magnetic flux sensor (52) that has a detection range in which magnetism is detected at a prescribed position, and that detects a change in magnetism occurring in association with the rotation of the rotor (30). The plurality of magnets (33, 33S, 33N) are arranged such that the polarities thereof undergo periodic changes according to the rotational direction of the rotor (30). The rotor (30) has magnetic flux singularities (35, 35A, 35B) at which the periodicity of response waveforms formed by magnetism of the respective magnets is disturbed, said magnetism being detected by the magnetic flux sensor (52) with respect to the time during which the rotor (30) makes one revolution.

Description

Cross - reference to related applications

[0001] This application is based on Japanese Patent Application No. 2023 - 032911 filed on March 3, 2023, the contents of which are incorporated herein by reference.

Technical Field

[0002] This disclosure relates to a rotational position detection device for a stepping motor.

Background Art

[0003] Conventionally, as a technology related to a rotational position detection device for a stepping motor, the technology described in Patent Document 1 is known. The technology related to Patent Document 1 is a technology related to a rotational position detection device for a stepping motor that constitutes an expansion valve for air conditioning, and it detects the state of the motor by using a response waveform output when a magnet arranged on a rotor passes through the detection range of a magnetic flux sensor.

[0004] Specifically, in Patent Document 1, in addition to the case where no response waveform is output by the magnetic flux sensor, when the length of the period of the response waveform deviates from a threshold value, it determines that the motor has experienced out - of - tune or abnormal stop.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

[0006] Here, when the stepping motor is abnormal, there may be a phenomenon where, although the motor has experienced out - of - tune or abnormal stop, the response waveform output from the magnetic flux sensor is the same as that in the normal state. Hereinafter, the response waveform output in this case is referred to as a pseudo - normal waveform.

[0007] When a pseudo-normal waveform is output, as time passes, the response waveform from the magnetic flux sensor changes from a pseudo-normal waveform to an abnormal waveform, either by the waveform disappearing or the period length falling outside the threshold. For this reason, motor abnormalities can also be detected by the technology described in Patent Document 1 as time progresses.

[0008] However, if the motor malfunction progresses while waiting for time to pass, a discrepancy will develop between the control unit's perception and the motor's actual position, making accurate drive control difficult. Therefore, in order to maintain accurate drive control, it is necessary to quickly detect and address motor malfunctions.

[0009] Furthermore, when a pseudo-normal waveform is output, measuring the magnetic flux waveform at the magnetic flux sensor reveals that the amplitude of the magnetic flux waveform is smaller. Here, we consider the case where the amplitude of the magnetic flux waveform in the case of a motor malfunction is smaller than in the normal state, but a sensor that outputs a digital value of ON / OFF for magnetic flux detection, such as a Hall IC, is used. Under these conditions, if the strength of the magnetic flux exceeds the detection threshold of the magnetic flux sensor, the magnetic flux sensor may output a pseudo-normal waveform similar to that in the normal state.

[0010] If the detection threshold of the magnetic flux sensor can be set to eliminate the reduced magnetic flux waveform caused by motor malfunction, then a false normal waveform will not be output. However, considering variations and deterioration of the rotor magnets and variations in the magnetic flux sensor, it is difficult to set a detection threshold that can reliably eliminate the output of a false normal waveform.

[0011] In view of the above, this disclosure aims to provide a rotational position detection device for a stepping motor that can reliably and quickly detect the presence or absence of a motor abnormality in the stepping motor with a simple configuration using the response waveform of the rotor's magnet and a magnetic flux sensor.

[0012] A rotational position detection device for a stepping motor according to one aspect of this disclosure is used in a stepping motor equipped with a rotor having a plurality of magnets arranged in a ring shape, and is a rotational position detection device for detecting the rotational position of the rotor. The rotational position detection device has a detection range for detecting magnetism at predetermined positions and has a magnetic flux sensor for detecting changes in magnetism accompanying the rotation of the rotor. The plurality of magnets are arranged such that their polarity changes periodically according to the direction of rotation of the rotor. The rotor has a magnetic flux singularity that disrupts the periodicity of the response waveform due to the magnetism of the plurality of magnets detected by the magnetic flux sensor with respect to the time it takes for the rotor to complete one rotation. A magnetic flux singularity is formed by combining a magnetic section made of magnetic material and a non-magnetic section configured to exhibit non-magnetic properties, in the portion of the rotor that passes through the detection range of the magnetic flux sensor during one rotation.

[0013] Therefore, according to the rotational position detection device for stepping motors, when the rotor is rotating normally, the response waveform of the magnetic flux sensor output during the time it takes for the rotor to complete one rotation will include waveforms originating from magnetic flux singularities, thus disrupting the periodicity. In other words, even if the motor is out of step or has stopped abnormally, if the response waveform output from the magnetic flux sensor shows a pseudo-normal waveform that changes periodically as if it were normal, it is possible to determine this based on the presence or absence of waveforms originating from magnetic flux singularities.

[0014] In other words, a rotational position detection device for a stepping motor can quickly detect abnormalities in a stepping motor that produce a pseudo-normal waveform by checking for the presence or absence of waveforms originating from magnetic flux singularities in the response waveform from a magnetic flux sensor, thereby suppressing the progression of the abnormality. [Brief explanation of the drawing]

[0015] The above-mentioned and other purposes, features, and benefits of this disclosure will become clearer from the detailed description below, with reference to the attached drawings. [Figure 1] This is a cross-sectional view showing the configuration of an expansion valve according to the first embodiment. [Figure 2] This is an explanatory diagram showing the configuration of the magnetic flux singularity of the rotor and the magnetic flux sensor applied to the expansion valve according to the first embodiment. [Figure 3]It is an explanatory diagram showing an example of a state in which a pseudo-normal waveform is generated. [Figure 4] It is an explanatory diagram showing the relationship between the pseudo-normal waveform and the change in magnetic flux strength with respect to the magnetic flux sensor. [Figure 5] It is an explanatory diagram showing an example of the response waveform of the magnetic flux sensor according to the first embodiment. [Figure 6] It is a flowchart of the error detection process of the stepping motor. [Figure 7] It is a flowchart of the rotor rotation position identification process of the stepping motor. [Figure 8] It is a flowchart of the speed adjustment process when the expansion valve is fully closed. [Figure 9] It is a flowchart of the tightening amount adjustment process for the expansion valve. [Figure 10] It is an explanatory diagram showing the magnetic flux singularity of the rotor applied to the expansion valve according to the second embodiment and the configuration of the magnetic flux sensor. [Figure 11] It is an explanatory diagram showing an example of the response waveform when the rotor rotates in the valve opening direction in the expansion valve according to the second embodiment. [Figure 12] It is an explanatory diagram showing an example of the response waveform when the rotor rotates in the valve closing direction in the expansion valve according to the second embodiment. [Figure 13] It is an explanatory diagram showing the magnetic flux singularity of the rotor applied to the expansion valve according to the third embodiment and the configuration of the magnetic flux sensor.

Modes for Carrying Out the Invention

[0016] Hereinafter, a plurality of embodiments for implementing the present disclosure will be described with reference to the drawings. In each embodiment, parts corresponding to those described in the preceding embodiment may be denoted by the same reference numerals and redundant descriptions may be omitted. When only a part of the configuration is described in each embodiment, other embodiments described previously can be applied to other parts of the configuration. Not only combinations of parts explicitly shown to be combinable in each embodiment, but also partial combinations of embodiments are possible without particular hindrance to the combination, even if not explicitly stated.

[0017] (First Embodiment) The first embodiment in the present disclosure will be described with reference to FIGS. 1 to 12. In the first embodiment, the rotational position detection device according to the present disclosure is applied to an expansion valve 100 which is one of the component devices in a vapor compression refrigeration cycle. The refrigeration cycle has a compressor, a condenser, an expansion valve 100, and an evaporator. The compressor sucks in and compresses the refrigerant and discharges it, and the condenser dissipates heat from the refrigerant discharged from the compressor and condenses it. The expansion valve 100 decompresses and expands the refrigerant condensed in the condenser, and the evaporator absorbs heat from the refrigerant decompressed and expanded by the expansion valve 100 and evaporates it.

[0018] First, the configuration of the expansion valve 100 to which the rotational position detection device is applied will be described with reference to the drawings. As shown in FIG. 1, the expansion valve 100 according to the first embodiment is an electric expansion valve that adjusts the decompression amount by converting the rotational force of a stepping motor 60 into the vertical movement of a valve body 25 (that is, by changing the opening area due to the movement of the valve body 25). It is an electric expansion valve that moves the valve body 25 by a driving force to adjust the decompression amount of the refrigerant. That is, the rotational position detection device 1 detects the rotational position of a rotor 30 in the stepping motor 60 of the expansion valve 100. Then, based on the change over time of the detection result of the rotational position of the rotor 30, the rotational operation state of the rotor 30 in the stepping motor 60 of the expansion valve 100 is detected by the rotational position detection device 1.

[0019] The expansion valve 100 according to the first embodiment has a main body 10, a lower case 50, an upper case 65, and a bracket 70. The main body 10 has a valve body 11, a valve element 25, a partition member 26, etc.

[0020] The valve body 11 is a block-shaped component made of an aluminum alloy or the like. As shown in Figure 1, the valve body 11 has a refrigerant flow path 13 that connects the refrigerant inlet 12 and outlet 16. Furthermore, a valve chamber 14 is formed inside the valve body 11 on the refrigerant flow path 13, and a valve body 25 is slidably housed inside the valve chamber 14.

[0021] The inlet 12 is formed on one side of the valve body 11 and is the portion through which the refrigerant circulating in the refrigeration cycle flows into the expansion valve 100. The inlet 12 is connected to the valve chamber 14 via the refrigerant flow path 13.

[0022] Furthermore, an outlet 16 is formed on the lower surface of the valve body 11, allowing the refrigerant that has flowed through the valve chamber 14 to flow out of the expansion valve 100. A valve seat 15 is formed at the lower part of the valve chamber 14, connecting the valve chamber 14 and the outlet 16 via a refrigerant flow path 13.

[0023] In the first embodiment, an inlet 12 was formed on the side surface of the valve body 11 and an outlet 16 was formed on the lower surface of the valve body 11, but the configuration is not limited to this. For example, it is also possible to adopt a configuration in which an inlet is formed on the lower surface of the valve body 11 and an outlet is formed on the side surface of the valve body 11. In this configuration, the components for driving the valve body 25 (i.e., a stepping motor 60, etc.) may be placed on the low-pressure side.

[0024] Furthermore, a through-hole 17 is formed in the upper part of the valve body 11. The through-hole 17 is formed to connect the upper surface of the valve body 11 with the central portion of the upper surface of the valve chamber 14. Inside the through-hole 17 is a part of the valve body 25 that moves vertically by the driving force transmitted via the output shaft 45 of the stepping motor 60 and the power transmission unit 20.

[0025] The valve body 25 receives driving force from the rotor 30 of a stepping motor 60 located above the valve body 11, via the through hole 17 and the power transmission unit 20 located above it. The power transmission unit 20 includes a lead screw mechanism that converts the rotational motion generated by the rotor 30 into linear motion and transmits it to the valve body 25.

[0026] The valve body 25 moves axially (up and down in Figure 1) due to the driving force from the rotor 30, thereby approaching or moving away from the valve seat 15. In addition, in the expansion valve 100, the refrigerant flow path can be closed by bringing the valve body 25 into contact with the valve seat 15. Therefore, the valve body 25 corresponds to an example of a moving member, and the valve seat 15 corresponds to an example of a restricting part.

[0027] The relative movement of the valve body 25 with respect to the valve seat 15 allows the expansion valve 100 to adjust the opening of the refrigerant flow path. As the refrigerant flows through the refrigerant flow path 13, it expands under reduced pressure due to the throttling action in the gap between the valve body 25 and the valve seat 15. Therefore, the expansion valve 100 can adjust the amount of refrigerant pressure reduction in accordance with the adjustment of the opening.

[0028] As shown in Figure 1, a partition member 26 is fixed to the upper surface of the valve body 11. It is formed in a cylindrical shape from a metal such as stainless steel and is a rotor housing member that houses the rotor 30. The partition member 26 is arranged coaxially with the valve body 25.

[0029] One end of the partition member 26 (the upper end in Figure 3) is closed. The other end of the partition member 26 (the lower end in Figure 1) is open and in close contact with the valve body 11. Therefore, high-pressure refrigerant before depressurization is present in the internal space of the partition member 26, and the partition member 26 acts as a partition between the refrigerant-filled circuit containing the high-pressure refrigerant and the outside. Specifically, an O-ring is placed between the partition member 26 and the valve body 11, and the partition member 26 and the valve body 11 are sealed and fixed by fastening a male thread formed on the outer circumferential surface of the partition member 26 to a female thread formed on the inner circumferential surface of the valve body 11.

[0030] The rotor 30 is the rotor of the stepping motor 60 and rotates when current is supplied to the stator coil 51A of the stator 51, which is the stator. The rotation of the rotor 30 generates the driving force to drive the valve body 25. The stepping motor 60 consists of the rotor 30 and the stator 51 and is used as an electric actuator to displace the valve body 25.

[0031] The rotor 30 has a plurality of magnetic columns 33. The plurality of magnetic columns 33 are arranged along the outer surface of the cylindrical rotor 30 at predetermined intervals. The plurality of magnetic columns 33 are arranged so that the south poles and north poles alternate in the circumferential direction of the rotor 30. The specific configuration of the rotor 30 will be described in detail later.

[0032] The expansion valve 100 generates a driving force to move the valve body 25 by rotating the rotor 30 around the rotation axis 31 through the action of the rotating magnetic field generated in the stator coil 51A of the stator 51 when energized and the multiple magnet pillars 33 of the rotor 30.

[0033] The driving force generated by the rotation of the rotor 30 is transmitted to the output shaft 45 via the planetary gear mechanism 40. The planetary gear mechanism 40 is located below the rotor 30 and reduces the angular velocity output by the rotor 30 by a predetermined reduction ratio before outputting it.

[0034] The planetary gear mechanism 40, although not shown in the diagram, includes a sun gear, multiple planetary gears, a fixed gear, and an output gear. The planetary gears are arranged around the outer circumference of the sun gear, and the fixed gear (a ring gear) and the output gear are arranged around the outer circumference of the planetary gears. The sun gear is positioned inside the inner planetary gears of the rotor 30 and is formed to be integrated with the rotor 30. Therefore, the sun gear rotates in sync with the rotation of the rotor 30. The ring-shaped fixed gear and the output gear have internal teeth with a predetermined number of teeth formed on their inner surfaces.

[0035] The output gear rotatably supports multiple (three in this embodiment) planetary gears. Each planetary gear is positioned between the external teeth of the sun gear and the internal teeth of the stationary gear, and is supported by the output gear so as to mesh with the external teeth of the sun gear and the internal teeth of the stationary gear, respectively. The lower surface of the output gear is formed so that the output gear and the output shaft 45 are integrated into one unit.

[0036] Below the rotor 30 and the planetary gear mechanism 40, a power transmission unit 20 is positioned. As described above, the power transmission unit 20 includes a lead screw mechanism for converting the rotation of the output gear into movement in the valve driving direction, and a mechanism for connecting rotational force while absorbing the shift of the lead screw mechanism in the rotation axis direction and the shift with the output gear rotation part. The power transmission unit 20 converts the rotational motion transmitted from the output shaft 45 into linear motion and transmits it to the valve body 25 without changing the relative position of the rotor 30 in the axial direction of the expansion valve 100.

[0037] As shown in Figure 1, a lower case 50 is attached to the upper surface of the valve body 11. The lower case 50 is formed to surround the partition member 26 from the outside and houses the stator 51, the partition member 26, the magnetic flux sensor 52, and the control board 53. Together with the upper case 65, the lower case 50 constitutes a waterproof case.

[0038] A cylindrical section 50A is open at the bottom of the lower case 50, into which the partition member 26 is inserted coaxially. An O-ring 55 seal is provided in the gap between the cylindrical section 50A of the lower case 50 and the partition member 26. The O-ring 55 is positioned between the cylindrical section 50A and the partition member 26 to prevent liquid from entering the interior of the lower case 50.

[0039] The stator 51 is positioned coaxially with the rotor 30 and the partition member 26, radially outward from the rotor 30 and the partition member 26. The stator 51 is equipped with a stator coil 51A, and energizing the stator coil 51A generates a rotating magnetic field for rotating the rotor 30. A holding portion for holding the magnetic flux sensor 52 is formed on the upper part of the stator 51. The holding portion is formed of a molded resin portion that covers the outside of the stator coil 51A.

[0040] The magnetic flux sensor 52 is a magnetic flux density detection unit that detects the magnetic flux density, and is composed of, for example, a Hall IC. In other words, the magnetic flux sensor 52 is a magnetic flux change detection unit that detects changes in magnetic flux accompanying the rotation of the rotor 30.

[0041] The magnetic flux sensor 52 has a detection range that faces the rotor 30, and detects changes in magnetic flux caused by multiple magnet pillars 33 that pass through the detection range as the rotor 30 rotates. For example, when a north pole magnet pillar 33 (hereinafter referred to as magnet pillar 33N) located on the rotor 30 approaches the detection range and the magnetic flux strength related to the north pole exceeds a predetermined threshold (ON threshold), the magnetic flux sensor 52 starts outputting an ON signal. Then, when a south pole magnet pillar 33 (hereinafter referred to as magnet pillar 33S) located on the rotor 30 approaches the detection range and the magnetic flux strength related to the south pole exceeds a predetermined threshold (OFF threshold), the magnetic flux sensor 52 starts outputting an OFF signal.

[0042] As described above, since the magnet pillars 33N and 33S are arranged alternately on the outer surface of the rotor 30, when the rotor 30 is rotating normally, it basically outputs a response waveform in which ON and OFF signals are periodically repeated.

[0043] Furthermore, since the magnetic flux sensor 52 is held on the upper part of the stator 51, the positional accuracy of the magnetic flux sensor 52 relative to the rotor 30 can be improved compared to the case where the magnetic flux sensor 52 is held in the lower case 50. Consequently, the detection accuracy of the magnetic flux density by the magnetic flux sensor 52 can be improved.

[0044] The control board 53 is located inside the lower case 50, above the rotor 30, the partition member 26, and the stator 51. The control board 53 is communicatively connected to an air conditioning control device 80 for controlling the operation of the refrigeration cycle, and controls the operation of the expansion valve 100 based on control commands from the air conditioning control device 80. Specifically, the control board 53 controls the operation of the stepping motor 60 based on control commands from the air conditioning control device 80, thereby controlling the drive current to the stator coil 51A.

[0045] Furthermore, the control board 53 makes a determination regarding the rotational position of the rotor 30 in the stepping motor 60 based on the response signal from the magnetic flux sensor 52. That is, the control board 53 determines whether there is an error in the stepping motor 60 and controls the drive of the stepping motor 60 according to the position of the rotor 30, based on the response signal from the magnetic flux sensor 52. The control board 53 is an example of a control unit.

[0046] The upper case 65 is a lid member for sealing the lower case 50. Both the lower case 50 and the upper case 65 are made of resin. The lower case 50 and the upper case 65 are fixed together by resin welding, such as laser welding. This ensures that the lower case 50 and the upper case 65 are liquid-tightly sealed, preventing water from entering electrical control components such as the control board 53 and magnetic flux sensor 52.

[0047] The bracket 70 is a fixing member for securing the lower case 50 to the valve body 11. The bracket 70 is made of stainless steel and has an L-shaped flat plate form. One end of the bracket 70 is fastened to the valve body 11 with a fixing screw 70A, and the other end of the bracket 70 firmly holds the cylindrical portion 50A of the lower case 50.

[0048] With the expansion valve 100 configured in this way, the control board 53 controls the drive current to the stator coil 51A based on control commands from the air conditioning control device 80, controls the rotational movement of the rotor 30, and adjusts the relative position of the valve body 25 with respect to the valve seat 15. As a result, the amount of refrigerant pressure reduced in the expansion valve 100 is appropriately controlled.

[0049] Next, the configuration of the rotor 30 of the stepping motor 60 in the expansion valve 100 according to the first embodiment will be described in detail with reference to Figure 2. The rotor 30 of the stepping motor 60 according to the first embodiment has a rotor core 32 formed in a cylindrical shape with a closed upper surface. A rotation axis 31, which is the rotation center of the rotor 30, is formed at the center of the cylindrical rotor core 32. As described above, the rotation axis 31 of the rotor 30 is arranged coaxially with the output shaft 45, the valve body 25, and the valve seat 15 in the expansion valve 100.

[0050] As described above, multiple magnet pillars 33 are arranged on the outer surface of the rotor 30 at predetermined intervals. The multiple magnet pillars 33 consist of 12 magnet pillars 33N and 12 magnet pillars 33S, and are arranged so that the magnet pillars 33N and magnet pillars 33S alternate. The magnet pillars 33N are formed by molding a resin magnet to form its outer shape and then magnetizing it to show north pole polarity. The magnet pillars 33S are formed by molding a resin magnet to form its outer shape and then magnetizing it to show south pole polarity.

[0051] As shown in Figure 2, the magnetic flux sensor 52 is positioned radially outward of the rotor 30, and its detection range is set to detect changes in magnetic flux in the upper portion of the outer circumferential surface of the rotor 30.

[0052] In this embodiment, a magnetic flux singularity 35 is formed on the upper surface portion of the rotor 30. The magnetic flux singularity 35 is a portion that inhibits the periodic change in magnetic flux generated in the magnetic flux sensor 52 due to the alternating arrangement of magnetic columns 33N and 33S at predetermined intervals.

[0053] The magnetic flux singularity 35 is formed by combining a magnetic part 36 having either a south pole or north pole magnetism with a non-magnetic part 38 exhibiting non-magnetic properties in the portion of the rotor 30 that passes through the detection range of the magnetic flux sensor 52.

[0054] In the first embodiment, the magnetic section 36 is realized by an extension section 37 formed by extending the magnet column 33 to the upper surface portion of the rotor 30 that passes through the detection range of the magnetic flux sensor 52. Therefore, when the magnetic section 36 passes through the detection range of the magnetic flux sensor 52, the extension section 37 related to magnet column 33N and the extension section 37 related to magnet column 33S pass through alternately.

[0055] In the first embodiment, the non-magnetic portion 38 is formed by a cutout portion 39 that includes the magnet pillars 33 and cuts out the upper surface portion of the rotor 30 that passes through the detection range of the magnetic flux sensor 52. Specifically, as shown in Figure 2, the cutout portion 39 in the rotor 30 according to the first embodiment is formed by cutting out the upper surface portion of one magnet pillar 33S and the upper surface portion of an adjacent magnet pillar 33N from the upper surface portion of the rotor 30.

[0056] The area of ​​the rotor 30 that is cut out as the missing portion 39 is determined based on the detection range of the magnetic flux sensor 52, and is determined so that no part of the magnet column 33S is included within the detection range. Furthermore, if the rotor 30 is displaced axially (up and down) as it rotates due to the action of the lead screw mechanism, the portion of the rotor 30 that passes through the detection range of the magnetic flux sensor 52 also widens in the axial direction as the rotor 30 is displaced. In this case, the area of ​​the rotor 30 that is cut out as the missing portion 39 is determined considering the detection range of the magnetic flux sensor 52 and the amount of axial movement of the rotor 30 due to rotation, so that the missing portion 39 exhibits non-magnetic properties.

[0057] Next, we will explain, with reference to Figures 3 and 4, the pseudo-normal waveforms that interfere with the detection of rotational abnormalities in a rotor having multiple magnets, based on the period of the response waveform from a magnetic flux sensor. For example, Chinese Patent Application Publication No. 107763285 describes a technique for detecting rotor step-out or rotational abnormalities using multiple magnets arranged on the rotor and the response period of the response waveform from a magnetic flux sensor.

[0058] As described above, the magnetic flux sensor starts outputting an ON signal when, for example, the north pole magnet placed on the rotor approaches the detection range and the magnetic flux strength applied to the north pole exceeds the ON threshold. Then, as the north pole magnet moves away from the detection range, the magnetic flux strength applied to the north pole weakens.

[0059] Furthermore, when the south pole magnet positioned on the rotor approaches the detection range and the magnetic flux strength applied to the south pole exceeds the OFF threshold, the magnetic flux sensor begins outputting an OFF signal. Then, as the south pole magnet moves away from the detection range, the magnetic flux strength applied to the south pole weakens. Therefore, when the rotor is rotating normally, the response waveform of the magnetic flux sensor shows a waveform in which ON and OFF signals are periodically repeated at predetermined lengths.

[0060] Here, let's consider the response waveform when, for example, the rotor is rotating but occasionally loses synchronism. When the rotor loses synchronism, it takes time for the rotor's S pole or N pole to approach the detection range of the magnetic flux sensor. Therefore, in the response waveform of the magnetic flux sensor, the response period at the time of loss of synchronism becomes longer, and by comparing the length of the response period with that of normal operation, it is possible to detect whether or not the rotor has lost synchronism.

[0061] Next, we consider the case where the rotor does not rotate but vibrates due to the rotational magnetic field of the stator coil. When the rotor vibrates due to the stator coil, the north pole and south pole magnets on the rotor alternately move closer to the magnetic flux sensor as a result of the vibration. At this time, if the magnetic flux strength of the north pole and the magnetic flux strength of the south pole exceed the ON threshold and OFF threshold, an ON signal and an OFF signal are output.

[0062] For example, when the magnetic flux sensor and the north pole vibrate in close proximity, the magnetic flux strength related to the north pole exceeds the ON threshold, but the magnetic flux strength related to the south pole does not exceed the OFF threshold because the magnet related to the south pole is far from the detection range. Therefore, the response waveform when the magnetic flux sensor and the north pole vibrate in close proximity shows a waveform in which the ON signal continues, and by comparing the response period, it is possible to detect rotational abnormalities when the magnetic flux sensor and the north pole vibrate in close proximity.

[0063] Furthermore, when the magnetic flux sensor and the south pole vibrate in close proximity, the magnetic flux strength related to the south pole exceeds the OFF threshold, but the magnetic flux strength related to the north pole does not exceed the ON threshold because the magnet related to the north pole is far from the detection range. For this reason, the response waveform when the magnetic flux sensor and the south pole vibrate in close proximity shows a waveform in which the OFF signal continues, and by comparing the response period, it is possible to detect rotational abnormalities when the magnetic flux sensor and the south pole vibrate in close proximity.

[0064] Next, we consider the case where the rotor does not rotate but vibrates due to the rotational magnetic field of the stator coil, and where the vibration occurs at a different period than the excitation period of the stator coil (period of the applied pulse). As described above, the north pole and south pole magnets of the rotor alternately approach the detection range of the magnetic flux sensor as the rotor vibrates. At this time, even if the magnetic flux strength related to the north pole exceeds the ON threshold and the magnetic flux strength related to the south pole exceeds the OFF threshold, the response periods of the ON and OFF signals correspond to the period related to the rotor vibration and show a different period from the excitation period of the stator coil. Therefore, by comparing the response periods of the magnetic flux sensor, it is possible to detect rotational abnormalities in which the rotor vibrates at a different period than the excitation period of the stator coil within the detection range of the magnetic flux sensor.

[0065] Here, we consider the case where the rotor does not rotate but vibrates due to the rotational magnetic field of the stator coil, and where the vibration has the same period as the excitation period of the stator coil. In this case, the vibration is assumed to occur at a position where the magnetic flux sensor 52 is near the center of the magnet column 33N and the magnet column 33S, as shown in Figure 3.

[0066] When the magnet column 33N vibrates due to the rotational magnetic field of the stator coil 51A, it approaches the detection range of the magnetic flux sensor 52. Even when it is closest to the detection range of the magnetic flux sensor 52 during vibration, the magnetic flux strength related to the N pole is greater than the ON threshold, but smaller than when the rotor 30 is rotating normally.

[0067] As the stator coil 51A vibrates due to the rotating magnetic field, the magnet column 33N moves away from the detection range and returns to its original position, while the magnet column 33S approaches the detection range of the magnetic flux sensor 52. In this case, even when it is closest to the detection range of the magnetic flux sensor 52, the magnetic flux strength related to the S pole is greater than the OFF threshold, but smaller than when the rotor 30 is rotating normally.

[0068] Therefore, as shown in Figure 4, when the magnet column 33N approaches the detection range of the magnetic flux sensor 52 when it is induced to vibrate by the rotating magnetic field of the stator coil 51A, the output of an ON signal is initiated. Then, when the magnet column 33S approaches the detection range of the magnetic flux sensor 52, the output of an OFF signal is initiated.

[0069] In this case, the vibration of the rotor 30 has the same period as the excitation period of the stator coil 51A, so the response waveform from the magnetic flux sensor 52 will show the same waveform as the response waveform when the rotor 30 is rotating normally (i.e., the normal waveform). In this disclosure, the response waveform output from the magnetic flux sensor 52 that is the same waveform as the waveform when the rotor 30 is rotating normally, even though a rotational abnormality of the rotor 30 is occurring, is called a pseudo-normal waveform.

[0070] When the rotor 30 is vibrating in the manner shown in Figure 3, a response waveform is output from the magnetic flux sensor 52. At this time, in the technology described in Chinese Patent Application Publication No. 107763285, the response period of the response waveform from the magnetic flux sensor 52 (i.e., the pseudo-normal waveform) is the same as that of the normal waveform, so it is considered that the situation in which the rotor is vibrating due to being induced by the rotating magnetic field of the stator 51 cannot be detected.

[0071] In the rotor 30 of a stepping motor applied to an expansion valve, if vibration occurs due to the rotating magnetic field of the stator coil 51A, the detection of rotational abnormalities is delayed due to the pseudo-normal waveform. In this case, the control side that controls the drive of the expansion valve recognizes it as a normal state, but the actual rotor of the stepping motor continues to vibrate, so the discrepancy between the position recognized by the control side and the actual position of the stepping motor increases over time.

[0072] As a result, errors are introduced in the adjustment of the expansion valve opening during the operation control of the refrigeration cycle, causing the refrigerant flow rate in the refrigeration cycle to deviate from the control system's assumptions, which affects the performance of the refrigeration cycle.

[0073] Furthermore, since the opening degree of the expansion valve in the refrigeration cycle affects the amount of refrigerant oil contained in the refrigerant that returns to the compressor, errors in adjusting the valve opening degree of the expansion valve are thought to cause malfunctions in the components of the refrigeration cycle.

[0074] Next, the normal waveform in the expansion valve 100 according to the first embodiment will be described with reference to Figure 5. As described above, in the expansion valve 100 according to the first embodiment, when the rotor 30 of the stepping motor 60 rotates, the magnetic part 36 and the non-magnetic part 38, which are located on the upper surface side of the rotor 30, pass through the detection range of the magnetic flux sensor 52.

[0075] As described above, as the rotor 30 rotates, the extension 37 of the magnet column 33N approaches the detection range of the magnetic flux sensor 52, and the magnetic flux strength related to the north pole increases. When the magnetic flux strength related to the north pole exceeds the ON threshold, the magnetic flux sensor 52 outputs an ON signal.

[0076] As the extension 37 of the magnet column 33N moves away from the detection range of the magnetic flux sensor 52, the extension 37 of the magnet column 33S approaches the detection range of the magnetic flux sensor 52. As the extension 37 of the magnet column 33S approaches the detection range of the magnetic flux sensor 52, the magnetic flux strength related to the south pole increases. When the magnetic flux strength related to the south pole exceeds the OFF threshold, the magnetic flux sensor 52 outputs an OFF signal. As the extension 37 of the magnet column 33S moves away from the detection range of the magnetic flux sensor 52, the extension 37 of the magnet column 33N approaches the detection range of the magnetic flux sensor 52.

[0077] In this series of operations, in the first embodiment, the ON signal and OFF signal are repeatedly switched when the magnetic part 36 passes through the detection range of the magnetic flux sensor 52. The period of the ON signal and OFF signal when the magnetic part 36 passes through the detection range of the magnetic flux sensor 52 is called the normal period Pr.

[0078] As shown in Figure 2, a magnetic part 36 and a non-magnetic part 38 are arranged on the upper surface of the rotor 30, and the combination of the magnetic part 36 and the non-magnetic part 38 constitutes a magnetic flux singularity 35.

[0079] In the first embodiment, when the magnetic part 36 passes through the detection range of the magnetic flux sensor 52, the magnetic flux sensor 52 outputs a response waveform in which the ON signal and OFF signal switch with a normal period Pr. When the non-magnetic part 38 passes through the detection range of the magnetic flux sensor 52, the magnetic flux sensor 52 outputs a response waveform in which the ON signal and OFF signal switch with a period longer than the normal period Pr. In the first embodiment, in the response waveform of the magnetic flux sensor 52, the waveform in which the ON signal and OFF signal switch with a period longer than the normal period Pr due to the non-magnetic part 38 is called a singular waveform Sw.

[0080] Referring to Figure 5, the singular waveform Sw and singular waveform period Ps will be explained. As the rotor 30 of the stepping motor 60 rotates and the magnetic part 36 passes through the detection range of the magnetic flux sensor 52, the non-magnetic part 38 approaches the detection range of the magnetic flux sensor 52. In the example shown in Figure 5, as the non-magnetic part 38 approaches the detection range of the magnetic flux sensor 52, the extension 37 of the magnet column 33S constituting the magnetic part 36 passes through the detection range of the magnetic flux sensor 52 and moves away from the detection range. At this time, the magnetic flux strength of the S pole weakens as the extension 37 of the magnet column 33N moves away.

[0081] Furthermore, the response signal from the magnetic flux sensor 52 at this point indicates an OFF signal, which is output when the magnet column 33S approaches the detection range of the magnetic flux sensor 52 and the magnetic flux strength of the S pole exceeds the OFF threshold.

[0082] When the non-magnetic part 38 approaches the detection range of the magnetic flux sensor 52, the strength of the magnetic flux detected by the magnetic flux sensor 52 will be the magnetic flux originating from the magnetic part 36, as the magnetic flux originating from the non-magnetic part 38 will not be detected. Therefore, during the period when the non-magnetic part 38 is passing through the detection range of the magnetic flux sensor 52, the magnetic flux sensor 52 continues to output an OFF signal.

[0083] As the non-magnetic part 38 passes through the detection range of the magnetic flux sensor 52, the extension 37 of the magnet column 33N constituting the magnetic part 36 approaches the detection range of the magnetic flux sensor 52. Accordingly, the magnetic flux strength of the north pole increases as it approaches the detection range of the magnetic flux sensor 52. When the magnetic flux strength of the north pole exceeds the ON threshold, the magnetic flux sensor 52 outputs an ON signal. The output of this ON signal determines the end of the singular waveform Sw. In the first embodiment, the singular waveform period Ps, which is the period of the singular waveform Sw, is three times the length of the normal period Pr.

[0084] In the first embodiment, as shown in Figure 2, a non-magnetic portion 38 is formed at one location on the upper surface of the rotor 30, and the other portion is composed of a magnetic portion 36, so that one magnetic flux singularity 35 is formed on the rotor 30. Therefore, after the output of the singular waveform Sw ends, there is a period until one rotation in which the ON signal and OFF signal are switched and output at a normal period.

[0085] In other words, in the expansion valve 100 according to the first embodiment, if the response waveform of the magnetic flux sensor 52 includes a singular waveform Sw originating from the magnetic flux singularity 35 during the period in which the rotor 30 rotates once, it indicates that the rotor 30 is rotating. This makes it possible to distinguish between a normal waveform and a pseudo-normal waveform based on whether or not the response waveform of the magnetic flux sensor 52 includes the singular waveform Sw, and to detect rotational abnormalities of the rotor 30, such as the state in which the rotor 30 is vibrating as shown in Figure 3.

[0086] Next, an error detection process for detecting whether or not a rotational abnormality has occurred in the rotor 30 of the stepping motor 60 in the expansion valve 100 according to the first embodiment will be described with reference to Figure 6. In the expansion valve 100 according to the first embodiment, when the operation of the refrigeration cycle including the expansion valve 100 is started, the control board 53 starts executing the error detection process.

[0087] First, in step S1, it is determined whether the response period in the response waveform of the magnetic flux sensor 52 exceeds a threshold. The rotor 30 rotates due to the drive of the stepping motor 60, and the judgment process in step S1 is performed on the response waveform output from the magnetic flux sensor 52. The threshold in step S1 indicates the range of response periods that the rotor 30 can take when it is rotating normally, and is determined based on the application period of the excitation current to the stator coil 51A (the period of the applied pulse).

[0088] If the response period in the response waveform of the magnetic flux sensor 52 exceeds the threshold, the process proceeds to step S4 to determine that an abnormal rotation of the rotor 30 has occurred. On the other hand, if the response period of the magnetic flux sensor 52 does not exceed the threshold, the process proceeds to step S2.

[0089] An example of a rotational abnormality of the rotor 30 that can be determined by the judgment process in step S1 is when the rotor 30 is operating normally but occasionally loses step. This is because the rotational abnormality of the rotor 30 affects the length of the response period of the magnetic flux sensor 52. Furthermore, according to the judgment process in step S1, even when the rotor 30 is not rotating but is vibrating due to being induced by the rotating magnetic field of the stator coil 51A, if a response waveform different from the pseudo-normal waveform is output from the magnetic flux sensor 52, it can also be determined as a rotational abnormality.

[0090] In step S2, it is determined whether the control command from the air conditioning control device 80 is a rotation command in the same direction and whether it exceeds the number of excitation currents (pulses) required for one rotation. In other words, it is determined whether the drive control mode for the expansion valve 100 is instructed to be such that a singular waveform Sw originating from the magnetic flux singularity 35 is detected at least once.

[0091] If the control command from the air conditioning control device 80 is a rotation command in the same direction and exceeds the number of excitation currents (pulses) for one rotation, the response waveform from the magnetic flux sensor 52 contains a singular waveform Sw, and the process proceeds to step S3. On the other hand, if the control command from the air conditioning control device 80 is a mixture of rotation commands in the forward and reverse directions, or if it is less than or equal to the number of excitation currents (pulses) for one rotation of the rotor 30, the process returns to step S1. In this case, the portion that has passed through the detection range of the magnetic flux sensor 52 due to the rotation of the rotor 30 may not include the magnetic flux singularity 35.

[0092] In step S3, it is determined whether the response waveform from the magnetic flux sensor 52 contains a singular waveform Sw originating from the magnetic flux singularity 35. As described above, in the first embodiment, one magnetic flux singularity 35 is formed on the circumferential surface of the upper part of the rotor 30. Therefore, if one singular waveform Sw is included in the response waveform for a period sufficient for the rotor 30 to complete one rotation, it indicates that the rotor 30 is rotating normally. In this case, the process proceeds to step S6 to determine that the rotation of the rotor 30 is normal. After that, the process returns to step S1.

[0093] On the other hand, if the response waveform for a sufficient period of time for the rotor 30 to complete one rotation does not include one singular waveform Sw, it indicates that the rotor 30 is vibrating due to the rotational magnetic field of the stator coil 51A, and that a pseudo-normal waveform is being output. Therefore, if the response waveform for a sufficient period of time for the rotor 30 to complete one rotation does not include one singular waveform Sw, it is determined that a rotational abnormality of the rotor 30 has occurred.

[0094] In step S4, it is determined that an abnormal rotation of the rotor 30 has occurred. In step S5, error handling is performed. In the error handling, for example, the control board 53 outputs an error signal to the air conditioning control device 80 indicating that an abnormal rotation of the rotor 30 has occurred. The air conditioning control device 80 may also include a signal instructing the user to be notified of the error in response to this error signal. Simultaneously with the output of the error signal, the control mode for the operation of the expansion valve 100 may be changed. After the error handling is completed, the error detection process is terminated.

[0095] According to the rotational position detection device 1 of the first embodiment, by forming a magnetic flux singularity 35 on the rotor 30 of the stepping motor 60 and executing the error detection process shown in Figure 6, it is possible to detect rotational abnormalities of the rotor 30 in a manner in which a pseudo-normal waveform is output from the magnetic flux sensor 52.

[0096] This makes it possible to respond not only to rotational abnormalities of the rotor 30 identified by the response period in the response waveform from the magnetic flux sensor 52, but also to rotational abnormalities of the rotor 30 when a pseudo-normal waveform is output, thereby ensuring that the performance of the expansion valve 100 and the refrigeration cycle is reliably maintained.

[0097] Furthermore, if a configuration is adopted in which the magnetic flux of multiple magnets in the rotor 30 is detected by a magnetic flux sensor 52, a magnetic flux singularity 35 can be formed in the portion of the rotor 30 that passes through the detection range of the magnetic flux sensor 52, thereby enabling the detection of rotational abnormalities related to a pseudo-normal waveform.

[0098] Next, a method of drive control for the stepping motor 60 that utilizes the detection of a peculiar waveform Sw by the magnetic flux sensor 52 when the rotor 30 is rotating normally will be described with reference to the drawings.

[0099] First, the expansion valve 100 according to the first embodiment can perform rotor rotation position identification processing to determine the rotation position of the rotor 30 by utilizing the fact that a specific waveform Sw is detected when the rotor 30 is rotating normally.

[0100] As described above, the rotational position detection device 1 according to the first embodiment is applied to the expansion valve 100, and the rotational position of the rotor 30 corresponds to the position of the valve body 25, which is a movable member. Therefore, by performing rotor rotational position identification processing, it is possible to identify the position of the valve body 25 in the expansion valve 100 (i.e., the valve opening degree in the expansion valve 100).

[0101] Referring to Figure 7, the contents of the rotor rotation position determination process will be explained. Here, the execution of the rotor rotation position determination process begins when the valve body 25, which is the movable member of the expansion valve 100, is in contact with the valve seat 15, which is the regulating part, and the expansion valve 100 is in the initial drive position in the closed state. For example, this applies when the expansion valve 100 is adjusted to the closed state when the operation of the refrigeration cycle ends and the operation of the refrigeration cycle is restarted.

[0102] First, in step S11, it is determined whether the stepping motor 60 is operating in a direction that moves the valve body 25 away from the valve seat 15 (i.e., in the valve opening direction). The determination process in step S11 is determined according to the content of the control command output from the air conditioning control device 80 and the manner of the excitation current supplied to the stator coil 51A from the control board 53. If the stepping motor 60 is operating in the valve opening direction, the process proceeds to step S12. On the other hand, if the stepping motor 60 is operating in the valve closing direction, the process proceeds to step S14.

[0103] In step S12, it is determined whether or not a singular waveform Sw is detected in the response waveform output from the magnetic flux sensor 52 due to the operation of the stepping motor 60 in the valve-opening direction. If a singular waveform Sw is detected in the response waveform due to the operation of the stepping motor 60 in the valve-opening direction, the process proceeds to step S13 and 1 is added to the singularity counter. The singularity counter is stored in a memory device (e.g., RAM) mounted on the control board 53. After adding 1 to the singularity counter, the process proceeds to step S16. On the other hand, if a singular waveform Sw is not detected in the response waveform due to the operation of the stepping motor 60 in the valve-opening direction, the process returns to step S11.

[0104] Here, when the stepping motor 60 operates in the valve-opening direction, the rotor 30 rotates continuously in a predetermined direction. As described above, in the expansion valve 100 according to the first embodiment, when the rotor 30 rotates once, the response waveform of the magnetic flux sensor 52 should include one singular waveform Sw. Therefore, by counting the singular waveform Sw, the amount of rotation of the rotor 30 in the valve-opening direction can be determined. Furthermore, since the amount of rotation of the rotor 30 corresponds to the amount of movement of the valve body 25, the amount of displacement of the valve body 25 in the valve-opening direction in the expansion valve 100 can be determined.

[0105] In step S14, it is determined whether or not a singular waveform Sw is detected in the response waveform output from the magnetic flux sensor 52 due to the operation of the stepping motor 60 in the valve closing direction. If a singular waveform Sw is detected in the response waveform due to the operation of the stepping motor 60 in the valve closing direction, the process proceeds to step S15 and 1 is deducted from the singularity counter. After deducting 1 from the singularity counter, the process proceeds to step S16. On the other hand, if a singular waveform Sw is not detected in the response waveform due to the operation of the stepping motor 60 in the valve closing direction, the process returns to step S11.

[0106] When the stepping motor 60 operates in the valve-closing direction, the rotor 30 continues to rotate in the opposite direction to when it opens the valve. Therefore, by counting the peculiar waveform Sw in the response waveform when operating in the valve-closing direction, the amount of rotation of the rotor 30 in the valve-closing direction can be determined. Furthermore, since the amount of rotation of the rotor 30 corresponds to the amount of movement of the valve body 25, the amount of displacement of the valve body 25 in the valve-closing direction in the expansion valve 100 can be determined.

[0107] In step S16, the rotational position of the rotor 30 is updated based on the values ​​of the singularity counter updated in steps S13 and S16. In other words, the position of the valve body 25 in the expansion valve 100 is updated based on the values ​​of the singularity counter. After updating the rotational position of the rotor 30, the process returns to step S11 and the rotor rotational position determination process is repeated.

[0108] As described above, the rotor rotation position determination process starts with the valve body 25 in contact with the valve seat 15 and in a closed state. Therefore, the value of the singularity counter indicates the relative position of the valve body 25 with respect to the valve seat 15. Consequently, it is also possible to determine the valve opening degree of the expansion valve 100 using the value of the singularity counter.

[0109] According to the rotation position detection device 1 of the first embodiment, by utilizing the magnetic flux singularity 35 formed on the rotor 30, the detection accuracy of rotational abnormalities related to pseudo-normal waveforms can be improved, and at the same time, the rotational position of the rotor 30 in the stepping motor 60 can be accurately determined.

[0110] Next, an example of drive control of the stepping motor 60 using the value of the singularity counter updated in the rotor rotation position determination process described above will be explained with reference to Figure 8. Figure 8 is a flowchart of the drive control of the stepping motor 60 when the valve body 25 is brought into contact with the valve seat 15 of the expansion valve 100 to close the valve.

[0111] In this expansion valve, the valve body 25 is pressed against the valve seat 15 to close the valve, so noise is frequently generated when the valve seat 15 and the valve body 25 come into contact. Also, because the frequency of contact between the valve seat 15 and the valve body 25 is high, both components may wear down or deform due to contact. It is thought that the deformation and wear of the valve seat 15 and the valve body 25 progress more rapidly as the speed at which the valve body 25 contacts the valve seat 15 increases.

[0112] In light of this, the flowchart shown in Figure 8 utilizes the value of the singularity counter to implement a speed adjustment process when the expansion valve 100 closes.

[0113] As shown in Figure 8, first, in step S21, it is determined whether the expansion valve 100 is operating in the closing direction. The determination process in step S21 uses the same method as in step S11. If the expansion valve 100 is operating in the closing direction, the process proceeds to step S22. On the other hand, if the expansion valve 100 is operating in the opening direction, the process waits. Note that the driving of the stepping motor 60 in the opening direction is achieved by a process separate from the flowchart shown in Figure 8.

[0114] In step S22, it is determined whether the value of the singularity counter, which is updated in the rotor rotation position determination process, is below a reference value. As described above, in the rotor rotation position determination process, the initial state is the closed valve state in which the valve body 25 is in contact with the valve seat 15. Therefore, the value of the singularity counter is set to 0 for the closed valve state in which the valve body 25 is in contact with the valve seat 15. Thus, in other words, step S22 determines whether the operation of the expansion valve 100 in the closing direction is just before it becomes a closed valve state. Accordingly, the reference value is set as the value of the singularity counter that indicates the state just before the valve body 25 comes into contact with the valve seat 15 (for example, 1).

[0115] If the value of the singularity counter is greater than the reference value, it means that the valve body 25 is located sufficiently far from the valve seat 15, so the process proceeds to step S24 to execute the closing drive of the expansion valve 100 in normal mode.

[0116] In step S24, during the valve closing drive in normal mode, the operation of the stepping motor 60 is controlled so that the rotational speed of the rotor 30 (i.e., the movement speed of the valve body 25) is determined according to the control command output from the air conditioning control device 80. When the valve closing drive in normal mode is completed, the process returns to step S21.

[0117] On the other hand, if the value of the singularity counter is below the reference value, the valve body 25 is approaching the valve seat 15 and is just about to close, so the process proceeds to step S23 to execute the closing drive of the expansion valve 100 in deceleration mode.

[0118] In step S23, during the deceleration mode valve closing drive, the operation of the stepping motor 60 is controlled so that the rotational speed of the rotor 30 is slower than that of the normal mode valve closing drive. For example, in the deceleration mode drive control, the rotational speed of the rotor 30 is adjusted to 50% of the rotational speed of the rotor 30 specified by the control command output from the air conditioning control device 80. Once the valve closing drive in deceleration mode is completed, the process returns to step S21.

[0119] Furthermore, in the deceleration mode valve closing drive, it is sufficient that the rotational speed of the rotor 30 is slower than in the normal mode valve closing drive; the deceleration method is not limited to that of the normal mode. For example, the rotational speed of the rotor 30 may be gradually reduced as the valve body 25 approaches the valve seat 15.

[0120] According to the rotational position detection device 1 of the first embodiment, a magnetic flux singularity 35 is formed on the rotor 30 of the stepping motor 60 of the expansion valve 100, and the position of the valve body 25 relative to the valve seat 15 can be determined by detecting the magnetic flux singularity 35 with a magnetic flux sensor 52.

[0121] Furthermore, when the rotational position detection device 1 detects that the valve is about to close using the value of the singularity counter during the closing operation of the expansion valve 100, it performs a deceleration drive to close the valve. This slows down the speed at which the valve body 25 contacts the valve seat 15 when transitioning to the closed state, thereby suppressing the degree of deformation and wear of the valve seat 15 and the valve body 25.

[0122] Next, another example of drive control of the stepping motor 60 using the value of the singularity counter updated in the rotor rotation position determination process described above will be explained with reference to Figure 9. Figure 9 is a flowchart showing the adjustment control of the tightening amount in the tightening operation to correct the discrepancy between the actual position and the position recognized by the control circuit side regarding the rotation position of the rotor 30 in the stepping motor 60.

[0123] In the stepping motor 60, the amount of drive of the stepping motor 60 is recognized by the number of pulses of excitation current applied to the stator coil 51A. If a rotational abnormality such as step loss occurs, a discrepancy may occur between the actual rotational position of the rotor 30 and the recognized position on the control side, such as the air conditioning control device 80.

[0124] In the drive control of the stepping motor 60, if the discrepancy between the actual rotational position of the rotor 30 and the recognized position on the control device side becomes unacceptably large, the accuracy of the drive control of the stepping motor 60 can be improved by correcting the discrepancy to within an acceptable range.

[0125] As in the first embodiment, when a stepping motor 60 is used as the drive source for the expansion valve 100, the performance of the expansion valve 100 and the refrigeration cycle can be reliably and quickly ensured by appropriately correcting the amount of deviation.

[0126] The flowchart shown in Figure 9 is executed when the expansion valve 100 is closed. In step S31, it is determined whether the tightening execution condition is met. The tightening execution condition is the start condition for the operation that corrects the difference between the actual rotational position of the rotor 30 and the recognized position on the control device side. If the tightening execution condition is met, the process proceeds to step S32. On the other hand, if the tightening execution condition is not met, the process waits.

[0127] Here, we will explain specific examples of conditions for performing retightening. For example, one condition for performing retightening is when the expansion valve 100 has been used for a long period of time and the amount of displacement has become large enough to exceed the allowable limit. In this case, retightening is performed when the operation of the refrigeration cycle is stopped. In addition, conditions for performing retightening include when the amount of displacement exceeds a predetermined level after short-term use of the expansion valve 100, or when the opening and closing operation of the expansion valve 100 has been frequent. In this case, retightening is performed when the expansion valve 100 is closed.

[0128] In step S32, it is determined whether the difference between the estimated position of the rotor 30, estimated based on the control command from the air conditioning control device 80, and the actual position of the rotor 30, determined using the counting result of the singularity counter, is less than or equal to a predetermined value.

[0129] Here, the estimated position of the rotor 30 corresponds to the recognized position on the control device side and is estimated based on the control command from the air conditioning control device 80. Specifically, the estimated position of the rotor 30 is estimated based on the number of pulses of excitation current applied to the stator coil 51A, which are included in the control command from the air conditioning control device 80.

[0130] The actual position of the rotor 30 is determined based on the value of the singularity counter, which is updated in the rotor rotation position determination process shown in Figure 7. In addition to the value of the singularity counter, other information may be used when determining the actual position of the rotor 30. For example, by using the number of times the ON signal and OFF signal are switched at a normal period Pr when the magnetic part 36 passes through the detection range of the magnetic flux sensor 52, it is possible to determine the actual position of the rotor 30 in more detail.

[0131] The amount of displacement in step S32 is determined by the difference between the estimated position of the rotor 30 obtained in the manner described above and the actual position of the rotor 30. The predetermined value in step S32 is defined as the acceptable range of the difference between the estimated position of the rotor 30 and the actual position of the rotor 30. When determining the predetermined value, the operating history of the expansion valve 100 and the refrigeration cycle can be taken into consideration.

[0132] If the amount of misalignment is less than or equal to a predetermined value, the process proceeds to step S33. On the other hand, if the amount of misalignment is greater than the predetermined value, it indicates that the misalignment is large enough to affect the performance of the expansion valve 100 and the refrigeration cycle, so the process proceeds to step S36, where the expansion valve 100 is closed with the normal tightening amount. Specifically, from the state in which the valve body 25 is in contact with the valve seat 15 and the valve is closed, the rotor 30 is rotated in the closing direction an additional amount equal to a predetermined tightening amount. After the closing operation including the normal tightening amount is completed in step S36, the tightening amount adjustment process shown in Figure 9 is terminated.

[0133] In step S33, it is determined whether the value of the singularity counter is less than or equal to a set value. In this case, the set value is defined as the value of the singularity counter that indicates the state immediately before the valve body 25 contacts the valve seat 15. Therefore, in other words, step S33 is a determination of whether the operation of the expansion valve 100 in the closing direction is just before it reaches the closed state.

[0134] If the value of the singularity counter is less than or equal to the set value, the valve body 25 is just about to contact the valve seat 15 and close, so the process proceeds to step S35 and the expansion valve 100 is closed with a reduced tightening amount. The tightening amount achieved in the closing operation in step S35 is set to be less than the tightening amount performed in step S36. On the other hand, if the value of the singularity counter is greater than the set value, the valve body 25 is located away from the valve seat 15, so the process proceeds to step S34 and the expansion valve 100 is closed.

[0135] The valve closing operation in step S34 is achieved by rotating the rotor 30 in a predetermined direction so that the valve body 25 approaches the valve seat 15, in accordance with a control command from the air conditioning control device 80. Once the valve closing operation in step S34 is completed, the process returns to step S32.

[0136] When proceeding to step S35, the amount of deviation between the estimated position of the rotor 30 and the actual position of the rotor 30 is smaller than when proceeding to step S36. That is, in step S35, the amount of retightening is reduced to zero, and the correction is performed according to the magnitude of the deviation between the estimated position of the rotor 30 and the actual position of the rotor 30. When the valve closing operation, including retightening with the reduced retightening amount, is completed in step S35, the retightening amount adjustment process shown in Figure 9 is terminated.

[0137] As shown in Figure 9, the rotational position detection device 1 according to the first embodiment adjusts the amount of tightening performed during valve closing operation according to the magnitude of the discrepancy between the estimated position of the rotor 30 and the actual position of the rotor 30. This makes it possible to appropriately adjust the load on the stepping motor 60 and associated drive components and the time it takes for abnormal noise to occur, such as when tightening is performed with a large amount of tightening when the discrepancy is relatively small.

[0138] As a result, the rotational position detection device 1 can reduce the excessive load on the stepping motor 60 and other components of the expansion valve 100 by performing the tightening amount adjustment process shown in Figure 9. This allows the rotational position detection device 1 to improve the durability of the expansion valve 100 and the stepping motor 60, and to reduce the duration of vibration and abnormal noise during the tightening operation.

[0139] As described above, the rotational position detection device 1 for a stepping motor 60 according to the first embodiment is used in a stepping motor 60 equipped with a rotor 30 having a plurality of magnet pillars 33 arranged in an annular shape, and detects the rotational position of the rotor 30. The rotational position detection device 1 has a detection range for detecting magnetism at predetermined positions and has a magnetic flux sensor 52 that detects changes in magnetism accompanying the rotation of the rotor 30.

[0140] As shown in Figure 2, the multiple magnet pillars 33 are arranged so that their polarity changes periodically according to the rotation direction of the rotor 30. The rotor 30 has a magnetic flux singularity 35 that disrupts the periodicity of the response waveform due to the magnetism of the multiple magnet pillars 33 detected by the magnetic flux sensor 52 for the time it takes for the rotor 30 to complete one rotation.

[0141] Therefore, according to the rotational position detection device 1 for the stepping motor 60, when the rotor 30 is rotating normally, the response waveform of the magnetic flux sensor 52 output during the time it takes for the rotor 30 to complete one rotation includes a waveform originating from the magnetic flux singularity 35. The waveform originating from the magnetic flux singularity 35 disrupts the periodicity of the waveform in the response waveform. In other words, even though the stepping motor 60 is out of step or has stopped abnormally, if the response waveform output from the magnetic flux sensor 52 shows a pseudo-normal waveform that changes periodically as in normal conditions, this can be determined based on the presence or absence of a waveform originating from the magnetic flux singularity 35.

[0142] In other words, the rotational position detection device 1 for the stepping motor 60 can quickly detect rotational abnormalities of the stepping motor 60, which result in a pseudo-normal waveform, based on the presence or absence of a waveform originating from the magnetic flux singularity 35 in the response waveform from the magnetic flux sensor 52, and can suppress the progression of the rotational abnormality.

[0143] As shown in Figure 2, in the first embodiment, the magnetic flux singularity 35 of the rotor 30 is formed by combining a magnetic part 36 and a non-magnetic part 38 configured to exhibit non-magnetic properties in the portion that passes through the detection range of the magnetic flux sensor 52 when the rotor 30 rotates once.

[0144] By combining the magnetic part 36 and the non-magnetic part 38, the periodicity of magnetic flux changes in the rotor 30 can be inhibited with a simple configuration, thereby improving the speed and reliability of detecting rotational abnormalities related to pseudo-normal waveforms.

[0145] In the first embodiment, the magnetic portion 36 of the rotor 30 is composed of an extension portion 37 that extends axially from a plurality of magnetic columns 33 arranged along the outer circumference of the rotor 30. The plurality of magnetic columns 33 are composed of magnetic columns 33N that exhibit north pole magnetism and magnetic columns 33S that exhibit south pole magnetism, and the magnetic columns 33N and magnetic columns 33S are arranged alternately.

[0146] Therefore, in the first embodiment, the magnetic part 36 of the rotor 30 can be realized with a relatively simple configuration. Furthermore, when the rotor 30 rotates and the magnetic part 36 passes through the detection range of the magnetic flux sensor 52, the extensions 37 of the magnet column 33N and the extensions 37 of the magnet column 33S pass through alternately. As a result, when the magnetic part 36 passes through the detection range of the magnetic flux sensor 52, the magnetic flux strength related to the N pole and the magnetic flux strength related to the S pole increase periodically, so that the periodicity of the magnetic flux change can be detected in the response waveform of the magnetic flux sensor 52. In other words, by configuring the magnetic part 36 using extensions 37 of multiple magnet columns 33, it becomes possible to detect rotational abnormalities of the rotor 30 where the length of the period of the response waveform of the magnetic flux sensor 52 fluctuates.

[0147] As shown in Figure 6, according to the rotation position detection device 1 of the first embodiment, it is determined whether or not a rotational abnormality of the rotor 30 related to a pseudo-normal waveform has occurred based on the presence or absence of a peculiar waveform Sw in the response waveform output from the magnetic flux sensor 52 during one rotation of the rotor 30. If the response waveform from the magnetic flux sensor 52 includes a peculiar waveform Sw, it is determined that the rotation of the rotor 30 is normal, and if the peculiar waveform Sw is not included, it is determined that a rotational abnormality of the rotor 30 related to a pseudo-normal waveform has occurred.

[0148] Therefore, according to the rotation position detection device 1 of the first embodiment, the presence or absence of a peculiar waveform Sw in the response waveform from the magnetic flux sensor 52 makes it possible to quickly and reliably detect the occurrence of rotation abnormalities related to pseudo-normal waveforms, which were previously difficult to detect quickly.

[0149] The rotational position detection device 1 according to the first embodiment is applied to an expansion valve 100 that utilizes the driving force of a stepping motor 60 to move the valve body 25. As shown in Figure 7, the rotational position detection device 1 determines the position of the valve body 25 in the expansion valve 100 by counting the number of unique waveforms Sw detected in association with the rotation direction of the rotor 30.

[0150] According to the first embodiment, by effectively utilizing the configuration of a magnetic flux singularity 35 formed on the rotor 30, it becomes possible to accurately determine the position of the valve body 25 in the expansion valve 100 in conjunction with the rotational position of the rotor 30.

[0151] Furthermore, in the rotational position detection device 1 according to the first embodiment, the position of the valve body 25 relative to the valve seat 15 can be determined using the value of a singularity counter, which is obtained by counting the singular waveform Sw detected as the rotor 30 rotates. Then, when the expansion valve 100 is closing, if the valve body 25 approaches the valve seat 15 based on the value of the singularity counter, the rotational speed of the rotor 30 is reduced.

[0152] As a result, in the first embodiment, the speed at which the valve body 25 contacts the valve seat 15 can be reduced, allowing the valve seat 15 and the valve body 25 to make soft contact. In the expansion valve 100, the frequency of contact between the valve seat 15 and the valve body 25 is high, and deformation and wear due to contact affect the lifespan of the expansion valve 100. The rotational position detection device 1 can suppress deformation of the valve seat 15 and the valve body 25 by making soft contact between the valve seat 15 and the valve body 25, thereby extending the lifespan of the expansion valve 100.

[0153] Furthermore, according to the rotation position detection device 1 of the first embodiment, as shown in Figure 9, the tightening amount is adjusted using the value of the singularity counter, which counts the singular waveform Sw detected as the rotor 30 rotates, and a control command from the air conditioning control device 80. The value of the singularity counter indicates the actual rotation position of the rotor 30, and the control command indicates the position of the rotor 30 recognized by the control device, the air conditioning control device 80. The rotation position detection device 1 of the first embodiment adjusts the tightening amount according to the magnitude of the discrepancy between the actual rotation position of the rotor 30 and the recognized position of the rotor 30.

[0154] As shown in Figure 9, by adjusting the tightening amount according to the magnitude of the misalignment, excessive tightening operations to compensate for small misalignments are eliminated, thereby reducing excessive load on the stepping motor 60 and other components. Furthermore, the rotational position detection device 1 effectively utilizes the configuration of the magnetic flux singularity 35 of the rotor 30 to adjust the tightening amount, thereby improving the durability of the expansion valve 100 and the stepping motor 60.

[0155] (Second Embodiment) Next, a second embodiment, which differs from the embodiment described above, will be described with reference to Figures 10 to 12. In the rotational position detection device 1 for the stepping motor 60 according to the second embodiment, the configuration of the magnetic flux singularity 35 in the rotor 30 and the control method utilizing the magnetic flux singularity 35 differ from those of the first embodiment described above. Other components of the rotational position detection device 1 and expansion valve 100 according to the second embodiment (for example, the main body 10, the stator 51 in the stepping motor 60, the lower case 50, etc.) are the same as those of the first embodiment described above, so a further explanation will be omitted.

[0156] The rotational position detection device 1 according to the second embodiment is used in the expansion valve 100 for a stepping motor 60 which is used as a drive source for moving the valve body 25, similar to the first embodiment.

[0157] As shown in Figure 10, the configuration of the rotor 30 of the stepping motor 60 differs from that of the first embodiment in the second embodiment. Unlike the first embodiment, multiple magnetic flux singularities 35 are formed on the upper surface portion of the rotor 30 according to the second embodiment. Specifically, the rotor 30 according to the second embodiment has a first magnetic flux singularity 35A and a second magnetic flux singularity 35B.

[0158] The first magnetic flux singularity 35A and the second magnetic flux singularity 35B are configured, similar to the magnetic flux singularity 35 in the first embodiment, by combining a magnetic part 36 and a non-magnetic part 38 that exhibits non-magnetic properties in the portion of the rotor 30 that passes through the detection range of the magnetic flux sensor 52. The configuration of the magnetic part 36 and the non-magnetic part 38 is basically the same as in the first embodiment.

[0159] In the rotor 30 according to the second embodiment, the portion that passes through the detection range of the magnetic flux sensor 52 is formed in the order of a first non-magnetic portion 38A, a first magnetic portion 36A, a second non-magnetic portion 38B, and a second magnetic portion 36B, arranged in the circumferential direction.

[0160] The first non-magnetic portion 38A is formed by a cutout portion 39 that includes the upper surface portion of one magnet column 33S and the upper surface portion of an adjacent magnet column 33N within the upper surface portion of the rotor 30.

[0161] The first magnetic section 36A is composed of an extension 37 of a magnet column 33S adjacent to a magnet column 33N located below the first non-magnetic section 38A, and an extension 37 of a magnet column 33N adjacent to this extension 37 of magnet column 33S.

[0162] The second non-magnetic portion 38B is composed of a defect 39 positioned adjacent to the first magnetic portion 36A. The defect 39 constituting the second non-magnetic portion 38B is formed by cutting out the extensions 37 of the four magnet pillars 33 (i.e., two magnet pillars 33N and two magnet pillars 33S) from the upper surface portion of the rotor 30.

[0163] The second magnetic section 36B is formed on the upper surface portion of the rotor 30, between the second non-magnetic section 38B and the first non-magnetic section 38A. In the rotor 30 according to the second embodiment, similar to the first embodiment described above, 12 magnetic columns 33N and 12 magnetic columns 33S are arranged so that the magnetic columns 33N and magnetic columns 33S alternate. Therefore, the second magnetic section 36B is composed of extensions 37 of 8 magnetic columns 33N and extensions 37 of 8 magnetic columns 33S.

[0164] According to the rotor 30 of the second embodiment, the number of extensions 37 constituting the first magnetic section 36A and the second magnetic section 36B are different. Therefore, in the response waveform of the magnetic flux sensor 52 when the rotor 30 of the second embodiment rotates once, the number of normal periods Pr, which is the switching period between the ON signal and the OFF signal, will be different in the portion corresponding to the first magnetic section 36A and the portion corresponding to the second magnetic section 36B.

[0165] Furthermore, according to the rotor 30 of the second embodiment, the number of cut-out extensions 37 of the magnet column 33 differs between the defective portion 39 relating to the first non-magnetic portion 38A and the second non-magnetic portion 38B. As a result, in the response waveform of the magnetic flux sensor 52 when the rotor 30 of the second embodiment rotates once, a difference appears between the length of the first singular waveform Swa relating to the first non-magnetic portion 38A and the length of the second singular waveform Swb relating to the second non-magnetic portion 38B. The difference in the length of the first singular waveform Swa and the second singular waveform Swb in the response waveform corresponds to the difference in physical shape between the first non-magnetic portion 38A and the second non-magnetic portion 38B.

[0166] In the rotor 30 configured in this manner according to the second embodiment, the configuration of the response waveform output from the magnetic flux sensor 52 differs depending on the rotation direction of the rotor 30. First, the configuration of the response waveform when the rotor 30 is rotated in a predetermined direction (opening direction) during the opening operation of the expansion valve 100 will be explained with reference to Figure 11.

[0167] In the explanation of Figures 11 and 12, the period during which the first singular waveform Swa is output in the response waveform of the magnetic flux sensor 52 while the rotor 30 rotates once is referred to as the first singular waveform period Tsa, and the period during which the second singular waveform Swb is output is referred to as the second singular waveform period Tsb.

[0168] Furthermore, in the response waveform of the magnetic flux sensor 52 during one rotation of the rotor 30, the period during which the ON signal and OFF signal switch with a normal period Pr as the first magnetic part 36A passes through the detection range is called the first normal period Tra. The period during which the ON signal and OFF signal switch with a normal period Pr as the second magnetic part 36B passes through the detection range of the magnetic flux sensor 52 is called the second normal period Trb.

[0169] For example, when the expansion valve 100 is opened, the rotor 30 is rotated in the opening direction, and the first non-magnetic part 38A, the first magnetic part 36A, the second non-magnetic part 38B, and the second magnetic part 36B of the rotor 30 pass through the detection range of the magnetic flux sensor 52 in this order. After the second magnetic part 36B, the first non-magnetic part 38A moves into the detection range of the magnetic flux sensor 52.

[0170] Therefore, as shown in Figure 11, when the rotor 30 is rotated in the valve-opening direction (i.e., rotated in the forward direction), the response waveform of the magnetic flux sensor 52 is output in the following order: first singular waveform period Tsa, first normal period Tra, second singular waveform period Tsb, and second normal period Trb.

[0171] On the other hand, when the expansion valve 100 is closed, if the rotor 30 is rotated in the opposite direction to the opening direction (closing direction), the second magnetic part 36B, second non-magnetic part 38B, first magnetic part 36A, and first non-magnetic part 38A of the rotor 30 pass through the detection range of the magnetic flux sensor 52 in this order. After the first non-magnetic part 38A, the second magnetic part 36B moves into the detection range of the magnetic flux sensor 52.

[0172] In this case, as shown in Figure 12, when the rotor 30 is rotated in the valve closing direction (i.e., rotated in the reverse direction), the response waveform of the magnetic flux sensor 52 is output in the following order: second normal period Trb, second singular waveform period Tsb, first normal period Tra, and first singular waveform period Tsa.

[0173] Thus, according to the rotational position detection device 1 of the second embodiment, the actual rotational direction of the rotor 30 can be determined according to the configuration of the response waveform from the magnetic flux sensor 52 as the rotor 30 rotates. By utilizing this configuration, the rotational position detection device 1 of the second embodiment can determine whether the expansion valve 100 is actually performing an opening operation or a closing operation.

[0174] In the second embodiment, as shown in Figure 10, the configurations of the first non-magnetic part 38A and the second non-magnetic part 38B were different, as were the configurations of the first magnetic part 36A and the second magnetic part 36B. However, the embodiment is not limited to this configuration. Various embodiments can be adopted as long as the arrangement of the multiple magnetic flux singularities 35 is asymmetrical between rotation in the forward and reverse directions in a rotor 30 having multiple magnetic flux singularities 35 per revolution.

[0175] For example, even if the configurations of the first non-magnetic part 38A and the second non-magnetic part 38B are the same, an embodiment in which the configurations of the first magnetic part 36A and the second magnetic part 36B are different may be adopted. Similarly, even if the configurations of the first magnetic part 36A and the second magnetic part 36B are the same, an embodiment in which the configurations of the first non-magnetic part 38A and the second non-magnetic part 38B are different may be adopted.

[0176] Furthermore, in the second embodiment, similar to the first embodiment described above, the operation of the expansion valve 100 is performed according to control commands output from the air conditioning control device 80. Therefore, the rotational position detection device 1 according to the second embodiment can compare the rotational direction of the rotor 30 instructed by the control command from the air conditioning control device 80 with the rotational direction of the rotor 30 identified from the response waveform of the magnetic flux sensor 52.

[0177] As a result, the rotational position detection device 1 according to the second embodiment can determine whether or not the rotor 30 is rotating according to a command from the drive control side (i.e., the air conditioning control device 80 side), and can output an error signal if the rotor 30 is rotating in a direction different from the control command.

[0178] For example, by outputting an error signal to the air conditioning control device 80, the user can be notified that an error has occurred in the expansion valve 100, including the stepping motor 60. Furthermore, by outputting an error signal to the air conditioning control device 80, the operating mode of the refrigeration cycle, including the expansion valve 100, can be changed or stopped. If the operating mode of the stepping motor 60 differs from the control command on the drive control side (i.e., the air conditioning control device 80), it is anticipated that this could cause serious problems with the operation of the expansion valve 100 and the refrigeration cycle. Therefore, by changing the operating mode of the refrigeration cycle or stopping its operation, the error can be quickly resolved while minimizing the impact on other components in the refrigeration cycle.

[0179] As described above, according to the rotational position detection device 1 of the second embodiment, even when multiple magnetic flux singularities 35 are formed on the rotor 30, the effects and advantages obtained from the configuration and operation common to the above-described embodiment can be obtained.

[0180] As shown in Figure 10, the rotor 30 of the stepping motor 60 according to the second embodiment has a plurality of magnetic flux singularities 35, namely a first magnetic flux singularity 35A and a second magnetic flux singularity 35B. As shown in Figures 11 and 12, the plurality of magnetic flux singularities 35 are arranged such that the output periods of the plurality of singular waveforms Sw in the response waveform when the rotor 30 rotates in the forward direction are different from the output periods of the plurality of singular waveforms Sw in the response waveform when the rotor 30 rotates in the reverse direction.

[0181] Therefore, according to the rotational position detection device 1 of the second embodiment, the rotational direction in which the rotor 30 is actually rotating can be determined by referring to the output period of a peculiar waveform in the response waveform from the magnetic flux sensor 52.

[0182] Furthermore, the rotational position detection device 1 according to the second embodiment controls the drive of the stepping motor 60 according to the control command from the air conditioning control device 80. Therefore, the rotational position detection device 1 can compare the rotational direction of the rotor 30 instructed by the control command from the air conditioning control device 80 with the rotational direction of the rotor 30 identified from the response waveform of the magnetic flux sensor 52. As a result, it can determine whether the drive control of the stepping motor 60 is achieved according to the control command, and if the control command and the actual situation do not match, it can output an error signal.

[0183] (Third embodiment) Next, a third embodiment, which differs from the embodiments described above, will be explained with reference to Figure 13. In the rotational position detection device 1 according to the third embodiment, the configuration of the non-magnetic part 38 in the rotor 30 of the stepping motor 60 differs from that of the first embodiment described above. The other components in the third embodiment (main body 10, stator 51, lower case 50, etc.) are the same as those in the first embodiment described above, so a further explanation will be omitted.

[0184] As shown in Figure 13, the rotor 30 of the stepping motor 60 according to the third embodiment has a non-magnetic portion 38 formed to constitute a magnetic flux singularity 35. The non-magnetic portion 38 according to the third embodiment is formed by a cutout portion 39 that includes the upper surface portion of one magnet column 33N within the upper surface portion of the rotor 30.

[0185] Here, if the non-magnetic portion 38 of the rotor 30 is composed of a missing portion 39 obtained by cutting out a part of the rotor core 32 and the magnet column 33, as in the embodiment described above, the weight of the cut-out portion will decrease, which is thought to cause an imbalance in the weight balance and rotational balance of the rotor 30.

[0186] In view of this, the third embodiment employs a configuration in which, when forming the non-magnetic portion 38 of the rotor 30, a non-magnetic material 39A is filled into the portion cut out as the defect 39. Various materials can be used as the non-magnetic material 39A, as long as they have the same weight as the portion cut out as the defect 39 and are non-magnetic.

[0187] By configuring it in this way, in the third embodiment, the functions of the non-magnetic part 38 and the magnetic flux singularity 35 can be ensured, while at the same time the weight balance and rotational balance of the rotor 30 can be adjusted.

[0188] As described above, according to the rotational position detection device 1 of the third embodiment, even if the configuration of the non-magnetic part 38 for forming the magnetic flux singularity 35 of the rotor 30 is changed, the effects and advantages obtained from the configuration and operation common to the above-described embodiment can be obtained.

[0189] As shown in Figure 13, in the third embodiment, a non-magnetic material 39A is filled into a missing portion 39, which is a cutout of a part of the rotor core 32 and magnet column 33, to form a non-magnetic portion 38 for constituting a magnetic flux singularity 35 in the rotor 30.

[0190] As a result, the rotational position detection device 1 according to the third embodiment ensures the function of the non-magnetic portion 38 in the rotor 30, while simultaneously correcting the weight balance and rotational balance of the rotor 30 that have become uneven due to the formation of the defective portion 39.

[0191] This disclosure is not limited to the embodiments described above, and can be modified in various ways without departing from the spirit of this disclosure, as follows.

[0192] In the embodiments described above, the rotational position detection device for a stepping motor according to this disclosure was applied to an expansion valve 100 used in a refrigeration cycle, but the invention is not limited to this embodiment. It can be applied to various devices as long as they are equipped with a stepping motor 60. For example, the rotational position detection device for a stepping motor may be applied to valve devices such as on-off valves and multi-way valves.

[0193] Furthermore, in the embodiments described above, the control process shown in Figures 8 and 9 was explained as operation control when bringing the valve body 25, which corresponds to the moving member, into contact with the valve seat 15, which acts as a restricting part. However, the invention is not limited to this embodiment. That is, the control process shown in Figures 8 and 9 can be applied to various devices as long as the device is configured to move a specific member along a predetermined movement path by the rotation of the rotor 30 of the stepping motor 60 and bring it into contact with a restricting part arranged on the movement path.

[0194] In the rotor 30 of the first embodiment described above, the non-magnetic portion 38 is constructed using a missing portion 39 obtained by cutting out a part of the magnet column 33N and the magnet column 33S, and the non-magnetic portion 38 of the third embodiment also uses a missing portion 39 obtained by cutting out a part of the magnet column 33N. However, the configuration of the magnet column 33 that is cut out when constructing the missing portion 39 is not limited to the configuration described above. For example, the non-magnetic portion 38 may be constructed using a missing portion 39 obtained by cutting out a part of the magnet column 33S.

[0195] Furthermore, when a non-magnetic portion 38 is constructed using a missing portion 39 formed by cutting out multiple adjacent magnet columns 33, in the above-described embodiment, an even number of magnet columns 33 (equal numbers of magnet columns 33N and magnet columns 33S) were cut out, but the invention is not limited to this configuration. When constructing the missing portion 39, it is also possible to adopt a configuration in which an odd number of magnet columns 33 (one more of either magnet columns 33N or magnet columns 33S than the other) are cut out.

[0196] In the embodiment described above, the magnetic portion 36 of the rotor 30 was formed by an extension portion 37 made of the same material as the plurality of magnet columns 33S made of resin magnets, but the embodiment is not limited to this. The magnetic portion 36 does not need to be spaced and arranged at the same intervals as the plurality of magnet columns 33S that rotate the rotor 30, and a configuration in which the plurality of magnets are arranged at different intervals is also possible.

[0197] In the embodiment described above, the magnetic flux sensor 52 was positioned on one side of the rotor 30's rotation axis 31 (upper side in Figures 2, 10, and 13) so as to have a detection range toward the rotation center of the rotor 30, but the embodiment is not limited to this. The magnetic flux sensor 52 only needs to be able to detect changes in magnetism accompanying the rotation of the rotor 30, and may be positioned on the other side of the rotor 30's rotation axis 31 (lower side in Figure 2, etc.). Furthermore, it is also possible to adopt a configuration in which multiple magnetic flux sensors 52 are positioned for a single rotor 30. For example, a magnetic flux sensor 52 having a detection range on the upper part of the rotor 30 and a magnetic flux sensor 52 having a detection range on the lower part of the rotor 30 may be used in combination.

[0198] Furthermore, although the detection range of the magnetic flux sensor 52 in the above-described embodiment was set toward the radially inward direction of the rotor 30, it is not limited to this configuration. As long as it is possible to detect changes in magnetic flux accompanying the rotation of the rotor 30, the detection range of the magnetic flux sensor 52 may be set toward the axial direction of the rotor 30, as long as the detection range is set to face the rotor 30.

[0199] In the second embodiment, as shown in Figure 10, multiple non-magnetic portions 38 and multiple magnetic flux singularities 35 were formed by creating multiple cutouts 39 in the rotor 30. The arrangement of the multiple cutouts 39 in the rotor 30 is not limited to the above-described embodiment. For example, the multiple cutouts 39 in the rotor 30 may be arranged so as to balance the weight and rotation of the rotor 30. In this case, the size of the cutouts 39 (the number of magnet columns 33 cut out) may also be determined so as to balance the weight and rotation of the rotor 30.

[0200] The features of the rotational position detection device for a stepping motor disclosed herein are as follows: (Item 1) A rotational position detection device used in a stepping motor (60) equipped with a rotor (30) having a plurality of magnets (33, 33S, 33N) arranged in a ring shape, for detecting the rotational position of the rotor, The system includes a magnetic flux sensor (52) that has a detection range for detecting magnetism at a predetermined position and for detecting changes in magnetism accompanying the rotation of the rotor, The multiple magnets are arranged such that their polarity changes periodically according to the rotation direction of the rotor. The rotor is a rotational position detection device for a stepping motor having magnetic flux singularities (35, 35A, 35B) that disrupt the periodicity of the response waveform due to the magnetism of the multiple magnets detected by the magnetic flux sensor with respect to the time it takes for the rotor to complete one rotation. (Item 2) The rotational position detection device for a stepping motor according to item 1, wherein the magnetic flux singularity is formed by combining a magnetic part (36) made of a magnetic material and a non-magnetic part (38) configured to exhibit non-magnetic properties, in the portion that passes through the detection range of the magnetic flux sensor when the rotor rotates once. (Item 3) The plurality of magnets are composed of a plurality of magnetic columns arranged along the outer circumference of the rotor, The rotational position detection device for a stepping motor according to item 2, wherein the magnetic part (36) is composed of an extension (37) which extends the magnet column in the direction of the rotation axis of the rotor. (Item 4) The system includes a control unit (53) that controls the drive of the stepping motor, The control unit determines that the stepping motor is operating normally if the response waveform output from the magnetic flux sensor contains at least one singular waveform (Sw, Swa, Swb) based on the magnetic flux singularity during one rotation of the rotor. A rotational position detection device for a stepping motor according to any one of items 1 to 3, which determines that an abnormality has occurred in the stepping motor if the response waveform output from the magnetic flux sensor during one rotation of the rotor does not include the unusual waveform. (Item 5) A moving member (25) is arranged to move along a predetermined path by the driving force generated by the rotation of the rotor, A restricting unit (15) is arranged along the aforementioned movement path and restricts the movement of the moving member, The system includes a control unit (53) that controls the drive of the stepping motor, The control unit, The singular waveform (Sw) based on the magnetic flux singularity included in the response waveform output from the magnetic flux sensor is counted, and the position of the moving member that moves due to the rotation of the rotor is determined based on the counting result of the singular waveform, A rotational position detection device for a stepping motor according to any one of items 1 to 4, which controls the rotational speed of the rotor such that when the position of the identified moving member is within a predetermined distance from the restricting portion, the rotational speed of the rotor is lower than when the moving member is at a position further from the restricting portion than the predetermined distance. (Item 6) A moving member (25) is arranged to move along a predetermined path by the driving force generated by the rotation of the rotor, A restricting unit (15) is arranged along the aforementioned movement path and restricts the movement of the moving member, The system includes a control unit (53) that controls the drive of the stepping motor, The control unit, The singular waveform (Sw) based on the magnetic flux singularity included in the response waveform output from the magnetic flux sensor is counted, and the position of the moving member that moves due to the rotation of the rotor is determined based on the counting result of the singular waveform, Based on the number of excitation currents applied to the stepping motor, the position of the moving member that moves due to the rotation of the rotor is estimated. A rotational position detection device for a stepping motor described in any one of items 1 to 5, which determines the amount of displacement of the moving member based on the position of the moving member determined based on the counting result of the singular waveform and the estimated position of the moving member estimated based on the number of applied excitation currents, and adjusts the amount of rotation of the rotor according to the determined amount of displacement of the moving member. Place. ( Item 7) The system includes a control unit (53) that controls the drive of the stepping motor, The rotor has a plurality of magnetic flux singularities (35A, 35B), Multiple magnetic flux singularities are arranged in a portion of the magnetic flux sensor's detection range during one rotation of the rotor such that the output period of the singular waveform based on the magnetic flux singularity in the response waveform when the rotor rotates in the forward direction is different from the output period of the singular waveform in the response waveform when the rotor rotates in the reverse direction. The control unit (53) determines the rotation direction of the rotor according to the output period of the singular waveforms (Swa, Swb) in the response waveform output from the magnetic flux sensor, a rotation position detection device for a stepping motor according to any one of items 1 to 6. (Item 8) The control unit (53) determines whether the rotation direction instruction input to the stepping motor matches the rotation direction of the rotor identified according to the output period of the singular waveform in the response waveform. A rotational position detection device for a stepping motor according to item 7, which outputs an error signal indicating that there is a malfunction in the stepping motor if the identified rotational direction of the rotor does not match the rotational direction indicator.

[0201] This disclosure is described in accordance with the embodiments, but it is understood that this disclosure is not limited to such embodiments or structures. This disclosure also includes various modifications and variations within the equivalence. In addition, various combinations and forms, as well as other combinations and forms that include only one, more, or fewer of those elements, fall within the scope and concept of this disclosure.

Claims

1. A rotational position detection device used in a stepping motor (60) equipped with a rotor (30) having a plurality of magnets (33, 33S, 33N) arranged in a ring shape, for detecting the rotational position of the rotor, It has a magnetic flux sensor (52) that has a detection range for detecting magnetism at a predetermined position and detects changes in magnetism accompanying the rotation of the rotor, The multiple magnets are arranged such that their polarity changes periodically according to the rotation direction of the rotor. The rotor has magnetic flux singularities (35, 35A, 35B) that disrupt the periodicity of the response waveform due to the magnetism of the multiple magnets detected by the magnetic flux sensor with respect to the time it takes for the rotor to complete one rotation. The rotational position detection device for a stepping motor is configured such that the magnetic flux singularity is the portion that passes through the detection range of the magnetic flux sensor when the rotor rotates once, by combining a magnetic part (36) made of a magnetic material and a non-magnetic part (38) configured to exhibit non-magnetic properties.

2. The plurality of magnets are composed of a plurality of magnetic columns arranged along the outer circumference of the rotor, The rotational position detection device for a stepping motor according to claim 1, wherein the magnetic part (36) is composed of an extension (37) which extends the magnet column in the direction of the rotation axis of the rotor.

3. A rotational position detection device for use in a stepping motor (60) having a rotor (30) having a plurality of magnets (33, 33S, 33N) arranged in a ring shape, for detecting the rotational position of the rotor, A magnetic flux sensor (52) has a detection range for detecting magnetism at a predetermined position and detects changes in magnetism accompanying the rotation of the rotor, The system includes a control unit (53) that controls the drive of the stepping motor, The multiple magnets are arranged such that their polarity changes periodically according to the rotation direction of the rotor. The rotor has magnetic flux singularities (35, 35A, 35B) that disrupt the periodicity of the response waveform due to the magnetism of the multiple magnets detected by the magnetic flux sensor with respect to the time it takes for the rotor to complete one rotation. The control unit determines that the stepping motor is operating normally if the response waveform output from the magnetic flux sensor contains at least one singular waveform (Sw, Swa, Swb) based on the magnetic flux singularity during one rotation of the rotor. A rotational position detection device for a stepping motor that determines that an abnormality has occurred in the stepping motor if the response waveform output from the magnetic flux sensor during one rotation of the rotor does not include the unusual waveform.

4. A rotational position detection device for use in a stepping motor (60) having a rotor (30) having a plurality of magnets (33, 33S, 33N) arranged in a ring shape, for detecting the rotational position of the rotor, A magnetic flux sensor (52) has a detection range for detecting magnetism at a predetermined position and detects changes in magnetism accompanying the rotation of the rotor, A movable member (25) is arranged to move along a predetermined movement path by the driving force generated by the rotation of the rotor, A restricting unit (15) is arranged along the aforementioned movement path and restricts the movement of the moving member, It includes a control unit (53) that controls the driving of the stepping motor, The multiple magnets are arranged such that their polarity changes periodically according to the rotation direction of the rotor. The rotor has magnetic flux singularities (35, 35A, 35B) that disrupt the periodicity of the response waveform due to the magnetism of the multiple magnets detected by the magnetic flux sensor with respect to the time it takes for the rotor to complete one rotation. The control unit, The singular waveform (Sw) based on the magnetic flux singularity included in the response waveform output from the magnetic flux sensor is counted, and the position of the moving member that moves due to the rotation of the rotor is determined based on the counting result of the singular waveform, A rotational position detection device for a stepping motor that controls the rotational speed of the rotor such that when the position of the identified moving member is within a predetermined distance from the restricting portion, the rotational speed of the rotor is lower than when the moving member is further from the restricting portion than the predetermined distance.

5. A rotational position detection device for use in a stepping motor (60) having a rotor (30) having a plurality of magnets (33, 33S, 33N) arranged in a ring shape, for detecting the rotational position of the rotor, A magnetic flux sensor (52) has a detection range for detecting magnetism at a predetermined position and detects changes in magnetism accompanying the rotation of the rotor, A movable member (25) is arranged to move along a predetermined movement path by the driving force generated by the rotation of the rotor, A restricting unit (15) is arranged along the aforementioned movement path and restricts the movement of the moving member, It includes a control unit (53) that controls the driving of the stepping motor, The multiple magnets are arranged such that their polarity changes periodically according to the rotation direction of the rotor. The rotor has magnetic flux singularities (35, 35A, 35B) that disrupt the periodicity of the response waveform due to the magnetism of the multiple magnets detected by the magnetic flux sensor with respect to the time it takes for the rotor to complete one rotation. The control unit, The singular waveform (Sw) based on the magnetic flux singularity included in the response waveform output from the magnetic flux sensor is counted, and the position of the moving member that moves due to the rotation of the rotor is determined based on the counting result of the singular waveform, Based on the number of excitation currents applied to the stepping motor, the position of the moving member that moves due to the rotation of the rotor is estimated. A rotational position detection device for a stepping motor that determines the amount of displacement of the moving member based on the position of the moving member determined based on the counting result of the distinctive waveform and the estimated position of the moving member determined based on the number of applied excitation currents, and adjusts the amount of rotation of the rotor according to the determined amount of displacement of the moving member.

6. A rotational position detection device for use in a stepping motor (60) having a rotor (30) having a plurality of magnets (33, 33S, 33N) arranged in a ring shape, for detecting the rotational position of the rotor, A magnetic flux sensor (52) has a detection range for detecting magnetism at a predetermined position and detects changes in magnetism accompanying the rotation of the rotor, The system includes a control unit (53) that controls the drive of the stepping motor, The multiple magnets are arranged such that their polarity changes periodically according to the rotation direction of the rotor. The rotor has multiple magnetic flux singularities (35, 35A, 35B) that disrupt the periodicity of the response waveform due to the magnetism of the multiple magnets detected by the magnetic flux sensor, with respect to the time it takes for the rotor to complete one rotation. Multiple magnetic flux singularities are arranged in a portion of the magnetic flux sensor's detection range during one rotation of the rotor such that the output period of the singular waveform based on the magnetic flux singularity in the response waveform when the rotor rotates in the forward direction is different from the output period of the singular waveform in the response waveform when the rotor rotates in the reverse direction. The control unit (53) is a rotational position detection device for a stepping motor that determines the rotational direction of the rotor according to the output period of the singular waveforms (Swa, Swb) in the response waveform output from the magnetic flux sensor.

7. The control unit (53) determines whether the rotation direction instruction input to the stepping motor matches the rotation direction of the rotor, which is determined according to the output period of the singular waveform in the response waveform. The rotational position detection device for a stepping motor according to claim 6, wherein if the identified rotational direction of the rotor does not match the rotational direction indicator, an error signal indicating that there is a malfunction in the stepping motor is output.

Images