Measurement system and rotating body

Abstract

A measurement system according to one embodiment of the present disclosure comprises a rotating body, an optical sensor that irradiates a measurement surface of the rotating body with measurement light and receives reflected light of the measurement light reflected from the measurement surface, and a measurement device that measures the rotation speed of the rotating body on the basis of a change in the state of the reflected light reaching the optical sensor from the measurement surface. The measurement surface includes: a first measurement region that reflects the reflected light toward the optical sensor; and a second measurement region that is adjacent to the first measurement region in a circumferential direction around the rotation axis, the second measurement region passing through the irradiation position of the measurement light with respect to the measurement surface each time the rotating body rotates about the rotation axis. The second measurement region includes a marking in which the reflection light from when the irradiation position is positioned in the second measurement region is reflected in a direction different from the reflection direction of the reflection light from when the irradiation position is positioned in the first measurement region.

Description

Measuring systems and rotating bodies

[0001] The present disclosure relates to a measurement system and a rotating body.

[0002] Various methods for measuring the rotation speed of a rotating body, such as a turbocharger or a gas turbine, have been known (see, for example, Patent Documents 1 to 3). For example, a method is known in which a nut attached to the rotating shaft of the rotating body is magnetized and a magnetic sensor is used to measure changes in magnetic flux associated with the rotation of the rotating body. In the method described in Patent Document 1, a through hole is formed in a straight line extending radially through the rotating shaft and a hollow cap attached to the rotating shaft, and an optical sensor and a reflector are disposed on either side of the through hole. The rotation speed of the rotating body is measured by receiving light reflected from the reflector through the through hole with the optical sensor. In the method described in Patent Document 2, the rotation speed of the rotating body is measured by wireless communication between a wireless tag attached to the rotating body and a wireless tag reader / writer disposed opposite the wireless tag.

[0003] JP 2005-207805 A JP 2010-025832 A JP 2018-044462 A

[0004] Rotating bodies such as those described above may already have components that are strongly magnetic. In such cases, taking into consideration the influence of magnetism on the rotating body, there is a tendency to measure the rotation speed using sensors other than magnetic sensors. On the other hand, if a hollow cap and a through-hole are added to the rotating shaft of the rotating body, as in the method of Patent Document 1 using an optical sensor, the rotational balance of the rotating body is likely to be disrupted, especially during high-speed rotation. The same is true when a wireless tag is attached to the rotating shaft, as in the method of Patent Document 2 using wireless communication.

[0005] Another method for measuring rotation speed using an optical sensor involves applying black paint to a single circumferential location on a rotating body and measuring the rotation speed based on changes in the intensity of light reflected from the black paint. Applying black paint to a rotating body is less likely to cause the rotational balance of the rotating body to be disrupted than applying a hollow cap or through-hole to the rotating body. However, because applying black paint to a rotating body is typically done manually, uneven application of paint can sometimes prevent accurate measurement of the rotation speed of the rotating body.

[0006] The present disclosure describes a measurement system and a rotating body that can accurately measure the rotation speed of a rotating body while maintaining the rotational balance of the rotating body.

[0007] A measurement system according to one aspect of the present disclosure includes a rotating body including a shaft rotatable about a rotation axis, an optical sensor disposed facing a measurement surface that is a portion of the outer surface of the rotating body, irradiating measurement light onto the measurement surface and receiving reflected light of the measurement light reflected from the measurement surface, and a measurement device communicatively connected to the optical sensor and measuring the number of rotations of the rotating body based on changes in the state of the reflected light reaching the optical sensor from the measurement surface. The measurement surface includes a first measurement area that reflects the reflected light toward the optical sensor, and a second measurement area that is adjacent to the first measurement area in the circumferential direction of the rotation axis and passes through a position where the measurement light is irradiated on the measurement surface each time the rotating body rotates around the rotation axis. The second measurement area includes a marking that is processed to reflect reflected light when the irradiated position is located in the second measurement area in a direction different from the reflection direction of reflected light when the irradiated position is located in the first measurement area.

[0008] The measurement system and rotating body of the present disclosure can accurately measure the rotation speed of the rotating body while maintaining the rotational balance of the rotating body.

[0009] FIG. 1 is a diagram showing the configuration of a measurement system according to one embodiment. FIG. 2(a) is a side view showing an enlarged portion of the rotating body shown in FIG. 1. FIG. 2(b) is a front view showing the rotating body shown in FIG. 2(a). FIG. 3(a) is a diagram showing a state where a measurement light is irradiated onto a first measurement region of the rotating body shown in FIG. 2(a). FIG. 3(b) is a diagram showing a state where a measurement light is irradiated onto a second measurement region of the rotating body shown in FIG. 2(a). FIG. 4(a) is a graph showing the results of measuring the rotation speed of the rotating body shown in FIG. 1 using an optical sensor. FIG. 4(b) is a graph showing the results of measuring the rotation speed of the rotating body shown in FIG. 1 using a magnetic sensor as a reference example. FIG. 5(a) is a side view showing an enlarged portion of a rotating body according to Modification 1. FIG. 5(b) is a front view showing the rotating body shown in FIG. 5(a). FIG. 5(c) is a cross-sectional view of the boss portion taken along line A1-A1 in FIG. 5(a). FIG. 6A is a diagram showing a state when a measurement light is irradiated onto the first measurement region of the rotating body of FIG. 5A. FIG. 6B is a diagram showing a state when a measurement light is irradiated onto the second measurement region of the rotating body of FIG. 5A. FIG. 7A is a graph showing the measurement results of measuring the rotation speed of the rotating body of FIG. 5A using an optical sensor. FIG. 7B is a graph showing the measurement results of measuring the rotation speed of the rotating body of FIG. 5A using a magnetic sensor as a reference example. FIG. 8 is a diagram showing the configuration of a measurement system including a rotating body of Modification 2. FIG. 9 is a diagram showing the configuration of a measurement system including a rotating body of Modification 3. FIG. 10A is a diagram showing a state when a measurement light is irradiated onto the first measurement region on the shaft end face of the rotating body of FIG. 9. FIG. 10B is a diagram showing a state when a measurement light is irradiated onto the second measurement region on the shaft end face of the rotating body of FIG. 9. FIG. 11 is a diagram showing the configuration of a measurement system including a rotating body of Modification 4.

[0010] A measurement system according to one aspect of the present disclosure includes a rotating body including a shaft rotatable about a rotation axis, an optical sensor disposed facing a measurement surface that is a portion of the outer surface of the rotating body, irradiating measurement light onto the measurement surface and receiving reflected light of the measurement light reflected from the measurement surface, and a measurement device communicatively connected to the optical sensor and measuring the number of rotations of the rotating body based on changes in the state of the reflected light reaching the optical sensor from the measurement surface. The measurement surface includes a first measurement area that reflects the reflected light toward the optical sensor, and a second measurement area that is adjacent to the first measurement area in the circumferential direction of the rotation axis and passes through a position where the measurement light is irradiated on the measurement surface each time the rotating body rotates around the rotation axis. The second measurement area includes a marking that is processed to reflect reflected light when the irradiated position is located in the second measurement area in a direction different from the reflection direction of reflected light when the irradiated position is located in the first measurement area.

[0011] In the above measurement system, the second measurement area on the measurement surface of the rotating body includes a marking that is processed to reflect reflected light when the irradiation position where the measurement light is irradiated is located in the second measurement area in a direction different from the direction of reflection of reflected light when the irradiation position is located in the first measurement area. In this case, reflected light from the irradiation position in the second measurement area can be reflected in a direction different from that toward the optical sensor. As a result, the amount of reflected light that reaches the optical sensor from the irradiation position when the irradiation position is located in the second measurement area is smaller than the amount of reflected light that reaches the optical sensor from the irradiation position when the irradiation position is located in the first measurement area. Therefore, each time the marking in the second measurement area passes the irradiation position as the rotating body rotates, the amount of reflected light received by the optical sensor decreases. The rotation speed of the rotating body can be measured based on this change in the amount of reflected light. When the rotating body includes the above-processed marking, the rotating balance of the rotating body is less likely to be disrupted than when a separate component for measuring the rotation speed is added to the rotating body. Furthermore, since the markings that have been processed as described above can be formed uniformly and accurately on the measurement surface by machining, unlike when black paint is applied to the rotating body by hand, the risk of not being able to accurately measure the rotation speed of the rotating body due to uneven application, etc. is reduced. Therefore, with the above measurement system, the rotation speed of the rotating body can be accurately measured while maintaining the rotational balance of the rotating body.

[0012] In some embodiments, the marking may be a textured portion that is textured to diffuse reflected light. In this case, the marking can be formed on the rotating body by laser processing, in which a laser beam is irradiated onto the measuring surface of the rotating body. When the marking is formed on the rotating body by laser processing in this way, the rotational balance of the rotating body is less likely to be disrupted compared to when the marking is formed on the rotating body by cutting, in which a portion of the measuring surface of the rotating body is scraped away.

[0013] In some embodiments, the marking may be an inclined surface extending in a direction different from the direction in which the first measurement region extends in a cross section including the rotation axis. In this case, the marking can be easily formed on the rotating body by simply chamfering a part of the measurement surface of the rotating body.

[0014] In some embodiments, the optical sensor may be a laser sensor that irradiates the irradiation position with laser light as the measurement light. When a laser sensor is used as the optical sensor, the distance between the optical sensor and the rotating body can be longer than when a proximity sensor is used as the optical sensor. This reduces the risk of interference with other components due to the optical sensor being too close to the rotating body. As a result, it is possible to avoid the system configuration from becoming complicated in order to avoid interference between the optical sensor and other components.

[0015] In some embodiments, the rotating body may further include an impeller attached to the shaft. The measurement surface may be a portion of the outer surface of the impeller. An impeller is generally made of a material that is easier to machine than other parts such as a shaft. Therefore, markings can be easily formed by machining the impeller. Furthermore, unlike a shaft, the impeller is a part that can be removed from the rotating body and replaced, making it easy to correct markings. Furthermore, when markings are formed on an impeller, the impact of the markings on the rotational balance of the rotating body can be reduced compared to when markings are formed on a shaft. Furthermore, the impeller is often subject to correction to correct the rotational balance of the rotating body, and this correction is performed by machining using a chuck mechanism or the like. When markings are formed on this impeller, the positional relationship between the correction position of the impeller and the formation position of the markings can be detected together by machine. As a result, impeller correction and marking formation can be easily performed by machine.

[0016] In some embodiments, the impeller may include a cylindrical boss portion through which the shaft passes, a hub portion extending from the boss portion in the radial and circumferential directions of the rotation axis, and a plurality of blade portions rising from the hub portion. The boss portion may include a boss outer peripheral surface extending in the circumferential direction. The measurement surface may be the boss outer peripheral surface. In this case, the measurement light can be easily irradiated toward the measurement surface from a direction intersecting the rotation axis. Furthermore, the boss portion has a lower risk of breakage during high-speed rotation than the plurality of blade portions formed on the hub portion, so markings can be reliably maintained on the measurement surface.

[0017] In some embodiments, the marking may be formed on the outer peripheral surface of the boss at a position away from the boundary between the boss portion and the hub portion. In this case, the risk of the measurement light from the optical sensor being irradiated accidentally onto the multiple blades formed on the hub portion can be reduced. Furthermore, in this case, even if the optical sensor is positioned close to the measurement surface, the risk of the optical sensor interfering with the multiple blades of the hub portion can be reduced.

[0018] A rotating body according to another embodiment of the present disclosure is a rotating body including a shaft rotatable about a rotation axis. The rotating body includes a measurement surface, which is a portion of the outer surface of the rotating body, onto which measurement light from an optical sensor is irradiated. The measurement surface includes a first measurement area that reflects reflected light of the measurement light toward the optical sensor, and a second measurement area that is adjacent to the first measurement area in the circumferential direction of the rotation axis and passes through the irradiation position of the measurement light on the measurement surface each time the rotating body rotates around the rotation axis. The second measurement area includes a marking that is processed to reflect reflected light when the irradiation position is located in the second measurement area in a direction different from the reflection direction of reflected light when the irradiation position is located in the first measurement area. Because this rotating body has common features with the rotating body of the above-mentioned measurement system, it can achieve the same effects as those described above.

[0019] The measurement system and rotating body of the present disclosure will be described in detail below with reference to the accompanying drawings. In the description of the drawings, the same elements are given the same reference numerals, and duplicated explanations will be omitted.

[0020] 1 measures the rotation speed of a rotating body 10 that rotates about a rotation axis CL. The measurement system 1 includes, for example, the rotating body 10, an inverter 20, a rotation sensor 30 (optical sensor), a first vibration sensor 40, a second vibration sensor 50, a control device 60, and a measurement device 70.

[0021] The rotating body 10 is, for example, a component of a supercharger. The supercharger is applied, for example, to an internal combustion engine of a vehicle. The rotating body 10 includes, for example, a shaft 11, a first impeller 12, and a second impeller 13. The shaft 11 is, for example, a cylindrical component with a rotation axis CL as its central axis. The shaft 11 extends along an axial direction D1 in which the rotation axis CL extends. The shaft 11 is supported by bearings so as to be rotatable around the rotation axis CL. The first impeller 12 is attached to a first end 11a of the shaft 11. The second impeller 13 is attached to a second end 11b of the shaft 11. The second impeller 13 has a shape corresponding to that of the first impeller 12.

[0022] The inverter 20 is electrically connected to the rotating body 10. For example, the inverter 20 is integrated with the rotating body 10. The inverter 20 supplies driving power to the rotating body 10 for driving the rotating body 10 to rotate. A known circuit can be used as the circuit included in the inverter 20.

[0023] The rotation sensor 30 is disposed, for example, at a position facing the outer surface of the rotating body 10 in the radial direction D2 of the rotation axis CL. The rotation sensor 30 is an optical sensor that irradiates an irradiation position P30 on the outer surface of the rotating body 10 with measurement light L1, receives reflected light L2 from the irradiation position P30, and detects the amount of reflected light L2. In this embodiment, the rotation sensor 30 is a laser sensor that emits laser light as the measurement light L1. The rotation sensor 30 includes, for example, a sensor head 30a that irradiates the irradiation position P30 with the measurement light L1 and acquires the amount of reflected light L2 as an electrical signal φ3, and a sensor amplifier 30b that amplifies the electrical signal φ3 from the sensor head 30a. The rotation sensor 30 transmits the electrical signal φ30 amplified by the sensor amplifier 30b to the measurement device 70 as a detection result indicating the amount of reflected light L2. The distance in the radial direction D2 from the rotation sensor 30 to the irradiation position P30, that is, the detection distance of the rotation sensor 30, is, for example, in the range of 200 mm to 300 mm.

[0024] The first vibration sensor 40 is disposed, for example, at a position facing the first end 11a of the shaft 11 of the rotating body 10 in the radial direction D2. The first vibration sensor 40 is a displacement sensor that detects the vertical displacement of the rotating body 10 from changes in eddy currents generated at the first end 11a of the shaft 11 due to electromagnetic induction caused by a high-frequency magnetic field. The first vibration sensor 40 includes, for example, a sensor head 40a that generates a high-frequency magnetic field near the first end 11a and acquires the displacement of the rotating body 10 as an electric signal φ4, and a sensor amplifier 40b that amplifies the electric signal φ4 from the sensor head 40a. The first vibration sensor 40 transmits an electric signal φ40 from the sensor amplifier 40b to the measuring device 70 as a detection result indicating the vertical vibration of the rotating body 10. The distance in the radial direction D2 from the first vibration sensor 40 to the first end 11a, i.e., the detection distance of the first vibration sensor 40, is, for example, in the range of greater than 0 μm and less than or equal to 500 μm. The detection distance of the first vibration sensor 40 may be in the range of 50 μm to 500 μm, or in the range of 250 μm to 500 μm. The first vibration sensor 40 may be any other sensor such as an optical sensor, an acceleration sensor, or a speed sensor, as long as it can detect vibrations of the rotating body 10.

[0025] The second vibration sensor 50 is disposed, for example, at a position facing the second end 11b of the shaft 11 of the rotating body 10 in the radial direction D2. The second vibration sensor 50 is a displacement sensor that detects the vertical displacement of the rotating body 10 from changes in eddy currents generated at the second end 11b of the shaft 11 due to electromagnetic induction caused by a high-frequency magnetic field. The second vibration sensor 50 includes, for example, a sensor head 50a that generates a high-frequency magnetic field near the second end 11b and acquires the displacement of the rotating body 10 as an electric signal φ5, and a sensor amplifier 50b that amplifies the electric signal φ5 from the sensor head 50a. The second vibration sensor 50 transmits the electric signal φ50 from the sensor amplifier 50b to the measuring device 70 as a detection result indicating the vertical vibration of the rotating body 10. The distance in the radial direction D2 from the second vibration sensor 50 to the second end 11b, i.e., the detection distance of the second vibration sensor 50, is, for example, in the range of greater than 0 μm and less than or equal to 500 μm. The detection distance of the second vibration sensor 50 may be in the range of 50 μm to 500 μm, or in the range of 250 μm to 500 μm. The second vibration sensor 50 may be any other sensor such as an optical sensor, an acceleration sensor, or a speed sensor, as long as it can detect vibrations of the rotating body 10.

[0026] The control device 60 and the measurement device 70 are physically computers. For example, the control device 60 and the measurement device 70 are each configured as separate computers. The control device 60 and the measurement device 70 may also be configured as the same computer. The computers that make up the control device 60 and the measurement device 70 include, for example, one or more CPUs (processors), main storage devices (memories) such as RAM and ROM, a communication module that is a data transmission / reception device that transmits and receives data to and from the outside, and auxiliary storage devices such as semiconductor memory and hard disk drives. Each function of the control device 60 and the measurement device 70 is realized by loading one or more predetermined computer software programs onto hardware such as the CPU and RAM, operating the communication module under the control of the CPU, and reading and writing data from and to the RAM or auxiliary storage device.

[0027] The control device 60 is connected to the inverter 20 and the measuring device 70 via wire or wirelessly so as to be able to communicate with them. The control device 60 transmits a control signal φ6 to the inverter 20 to control the operation of the inverter 20. The control device 60 transmits an instruction signal φ60 to the measuring device 70 to instruct the measuring device 70 on the timing of measurement processing, etc.

[0028] The measuring device 70 is communicatively connected to the rotation sensor 30, the first vibration sensor 40, the second vibration sensor 50, and the control device 60 via wire or wirelessly. The measuring device 70 measures the rotation speed of the rotating body 10 using the electrical signal φ30 from the rotation sensor 30 in response to an instruction signal φ60 from the control device 60. The measuring device 70 measures the vibration characteristics of the rotating body 10 using the electrical signal φ40 from the first vibration sensor 40 and the electrical signal φ50 from the second vibration sensor 50 in response to the instruction signal φ60 from the control device 60.

[0029] The measuring device 70 includes, as functional components, a signal input unit 71 and a calculation unit 72, for example. The signal input unit 71 receives electrical signals φ30, φ40, and φ50 from the rotation sensor 30, the first vibration sensor 40, and the second vibration sensor 50. The signal input unit 71 samples, for example, the electrical signal φ30 from the rotation sensor 30 in synchronization with the electrical signals φ40 and φ50 from the first vibration sensor 40 and the second vibration sensor 50. The signal input unit 71 distinguishes between the electrical signals φ30, φ40, and φ50 and passes them to the calculation unit 72. The calculation unit 72 calculates the rotation speed of the rotating body 10 using the electrical signal φ30 from the signal input unit 71. The calculation unit 72 calculates the vibration characteristics of the rotating body 10 using the electrical signals φ40 and φ50 from the signal input unit 71. A specific method for measuring the rotation speed of the rotating body 10 using the calculation unit 72 will be described later.

[0030] When correction machining is performed on the outer surface of the rotating body 10 to correct the rotational balance of the rotating body 10, a first chuck mechanism 80 and a second chuck mechanism 90 are used. The first chuck mechanism 80 and the second chuck mechanism 90 are configured to be movable along the axial direction D1. The first chuck mechanism 80 is disposed at a position facing the first end 11a of the shaft 11 in the axial direction D1. The first chuck mechanism 80 grips the outer peripheral surface of the rotating body 10 workpiece from the first end 11a side. The first chuck mechanism 80 then rotates to correct the outer peripheral surface of the workpiece. The second chuck mechanism 90 grips the outer peripheral surface of the rotating body 10 workpiece from the second end 11b side. The second chuck mechanism 90 then rotates to correct the outer peripheral surface of the workpiece. When corrective processing is performed using the first chuck mechanism 80 and the second chuck mechanism 90, the first vibration sensor 40 and the second vibration sensor 50 can be retracted so as not to interfere with the first chuck mechanism 80 and the second chuck mechanism 90.

[0031] The configuration of the rotating body 10 will be described in more detail with reference to Figures 2(a) and 2(b). Figures 2(a) and 2(b) show the configuration of the rotating body 10 near the first impeller 12. The second impeller 13 has the same configuration as the first impeller 12, except that it does not have a marking M, which will be described later. Therefore, the second impeller 13 can be described in the same way as the first impeller 12, except for the marking M, and therefore a detailed description of the second impeller 13 will be omitted. The marking M may be formed on the second impeller 13 instead of the first impeller 12, or may be formed on both the first impeller 12 and the second impeller 13.

[0032] As shown in Figures 2(a) and 2(b), the shaft 11 includes, for example, a shaft end surface 11c and a shaft outer circumferential surface 11d. The shaft end surface 11c is a circular end surface located at one end of the shaft 11 in the axial direction D1. The diameter of the shaft end surface 11c is, for example, 4 mm or more and 6 mm or less. The shaft outer circumferential surface 11d is the outer circumferential surface of the shaft 11 extending along the circumferential direction D3 of the rotation axis CL. The shaft outer circumferential surface 11d extends from the shaft end surface 11c in the axial direction D1. The shaft outer circumferential surface 11d is, for example, a circumferential surface centered on the rotation axis CL.

[0033] The first impeller 12 includes, for example, a boss portion 14, a hub portion 15, and a plurality of blade portions 16. The boss portion 14 is, for example, cylindrical and centered on the rotation axis CL. The shaft 11 penetrates the inside of the boss portion 14 in the axial direction D1. The shaft end face 11c protrudes from the boss portion 14 in the axial direction D1. The boss portion 14 includes, for example, a first boss end face 14a, a second boss end face 14b, and a boss outer peripheral surface 14c (measurement surface). The first boss end face 14a and the second boss end face 14b are aligned in the axial direction D1. The shaft end face 11c protrudes from the first boss end face 14a. The boss outer peripheral surface 14c is the outer peripheral surface of the boss portion 14 extending along the circumferential direction D3. The boss outer peripheral surface 14c connects the first boss end surface 14a and the second boss end surface 14b in the axial direction D1. The boss outer peripheral surface 14c is, for example, a circumferential surface centered on the rotation axis CL. The diameter of the boss outer peripheral surface 14c is, for example, 18 mm or more and 20 mm or less.

[0034] The hub portion 15 is disposed on the opposite side of the boss portion 14 from the shaft end surface 11c in the axial direction D1. The hub portion 15 is connected to a second boss end surface 14b of the boss portion 14 in the axial direction D1. The hub portion 15 includes a hub surface 15a extending from the second boss end surface 14b in a direction inclined with respect to the axial direction D1 and the radial direction D2. A plurality of blade portions 16 rise from the hub surface 15a. The plurality of blade portions 16 are arranged at predetermined intervals along the circumferential direction D3.

[0035] In this embodiment, the boss outer peripheral surface 14c is configured as a measurement surface onto which measurement light L1 is irradiated to measure the rotation speed of the rotating body 10. A rotation sensor 30 emitting measurement light L1 is disposed at a position facing the boss outer peripheral surface 14c in the radial direction D2. The rotation sensor 30 irradiates the measurement light L1 toward the boss outer peripheral surface 14c in the radial direction D2. The optical axis direction of the rotation sensor 30 coincides with the radial direction D2, for example. An irradiation position P30 onto which the measurement light L1 from the rotation sensor 30 is irradiated is set on the boss outer peripheral surface 14c. The irradiation position P30 indicates the position of the irradiation spot of the measurement light L1 on the boss outer peripheral surface 14c. With respect to the rotating body 10 rotating around the rotation axis CL, the irradiation position P30 is set at a stationary position without rotation. The diameter of the irradiation spot of the measurement light L1 on the boss outer peripheral surface 14c is, for example, less than 1 mm.

[0036] The shaft end face 11c, the shaft outer peripheral surface 11d, the first boss end face 14a, the second boss end face 14b, the boss outer peripheral surface 14c, and the hub surface 15a described above constitute the outer surface of the rotating body 10. Of these surfaces, the first boss end face 14a, the second boss end face 14b, the boss outer peripheral surface 14c, and the hub surface 15a constitute the outer surface of the first impeller 12.

[0037] As shown in FIG. 2B , the boss outer peripheral surface 14c includes a first measurement region R1 and a second measurement region R2 adjacent to each other along the circumferential direction D3. The second measurement region R2 is a portion of the boss outer peripheral surface 14c along the circumferential direction D3. A marking M is formed in the second measurement region R2 as a rotation reference for measuring the rotation speed of the rotating body 10. The marking M rotates around the rotation axis CL together with the rotating body 10. The marking M passes through the irradiation position P30 each time the rotating body 10 rotates once. The marking M changes the state of the reflected light L2 that is reflected at the irradiation position P30 and reaches the rotation sensor 30. The change in the state of the reflected light L2 refers to, for example, a change in the amount of the reflected light L2 or a change in the intensity of the reflected light L2.

[0038] The marking M is a processed area that reflects the reflected light L2 from the irradiation position P30 when the irradiation position P30 is located in the second measurement area R2 in a direction different from the direction of reflection of the reflected light L2 when the irradiation position P30 is located in the first measurement area R1. The marking M reduces the amount of reflected light L2 that reaches the rotation sensor 30. The processing performed on the marking M is a predetermined surface treatment performed on the second measurement area R2. The surface treatment is, for example, laser processing or cutting processing performed using a machine. This mechanical processing forms a reflective surface on the marking M whose normal direction is a direction different from the reflection direction of the reflected light L2 from the irradiation position P30 in the first measurement area R1.

[0039] The marking M is, for example, an uneven portion formed by a laser marker. The marking M is a portion where the state of the boss outer peripheral surface 14c has been altered by irradiation with laser light. The marking M is formed by laser processing, in which laser light is irradiated onto the boss outer peripheral surface 14c. As a result of the alteration of the state of the boss outer peripheral surface 14c by the irradiation with laser light, the marking M is subjected to fine uneven processing due to the irradiation with laser light. The unevenness formed on the marking M includes at least a reflective surface whose normal direction is a direction different from the reflection direction of the reflected light L2 from the irradiation position P30 in the first measurement region R1. The marking M is configured to reflect the reflected light L2 reflected from the irradiation position P30 when the irradiation position P30 is located in the second measurement region R2 in a direction different from the reflection direction of the reflected light L2 when the irradiation position P30 is located in the first measurement region R1.

[0040] On the other hand, the first measurement region R1 is the remaining portion of the boss outer peripheral surface 14c excluding the second measurement region R2. No markings M are formed in the first measurement region R1. Therefore, the first measurement region R1 is configured as a smooth boss outer peripheral surface 14c that has not been subjected to mechanical processing such as laser processing.

[0041] As shown in FIG. 2A, when the rotating body 10 is viewed in the radial direction D2 perpendicular to the rotation axis CL, the marking M formed in the second measurement region R2 has a rectangular shape extending along the circumferential direction D3 of the rotation axis CL (see FIG. 2B). The marking M is formed, for example, on the boss outer peripheral surface 14c, at a position spaced apart in the axial direction D1 from the boundary between the hub portion 15 and the boss portion 14. That is, the marking M is formed at a position shifted toward the first boss end face 14a in the axial direction D1 from the second boss end face 14b that contacts the hub portion 15. As a result, a gap G is formed between the second boss end face 14b and the marking M in the axial direction D1. The marking M is in contact with the first boss end face 14a, for example, on the opposite side of the hub portion 15.

[0042] Considering that the diameter of the irradiation spot of the measurement light L1 is, for example, less than 1 mm, the width of the marking M in the axial direction D1 may be, for example, 1 mm or more and 2 mm or less. As shown in Figure 2 (b), when the rotating body 10 is viewed in the axial direction D1, the marking M is formed on the boss outer peripheral surface 14c within a range of an angle θ centered on the rotation axis CL. The angle θ may be, for example, 60 degrees.

[0043] As shown in FIG. 3A , when the irradiation position P30 is located in the first measurement region R1, which is configured as a smooth boss outer peripheral surface 14c, the normal direction of the first measurement region R1 at the irradiation position P30 coincides with the optical axis direction of the rotation sensor 30. Therefore, the measurement light L1 irradiated from the rotation sensor 30 along the radial direction D2 to the irradiation position P30 of the first measurement region R1 is reflected from the irradiation position P30 toward the rotation sensor 30 along the radial direction D2. In other words, the reflection direction of the reflected light L2 in the first measurement region R1 coincides with the irradiation direction of the measurement light L1 from the rotation sensor 30. The reflection direction of the reflected light L2 may be the optical axis direction of the reflected light L2. The irradiation direction of the measurement light L1 may be the optical axis direction of the measurement light L1.

[0044] On the other hand, the second measurement region R2, where the marking M is formed, has minute irregularities that diffusely reflect the measurement light L1. Therefore, the normal direction of the second measurement region R2 at the irradiation position P30 varies depending on the position in the second measurement region R2. The second measurement region R2 has multiple normal directions at the irradiation position P30 that are different from the optical axis direction of the rotation sensor 30. Therefore, as shown in FIG. 3B, most of the measurement light L1 irradiated from the rotation sensor 30 to the irradiation position P30 of the second measurement region R2 along the radial direction D2 is reflected at the irradiation position P30 of the second measurement region R2 in a direction different from the optical axis direction of the rotation sensor 30. In other words, the reflection direction of most of the reflected light L2 in the second measurement region R2 is different from the irradiation direction of the measurement light L1 from the rotation sensor 30.

[0045] In this way, the marking M reflects the reflected light L2 from the irradiation position P30 when the irradiation position P30 is located in the second measurement region R2 in a direction different from the reflection direction of the reflected light L2 when the irradiation position P30 is located in the first measurement region R1. The reflection direction of the reflected light L2 when the irradiation position P30 is located in the first measurement region R1 may be the normal direction of the first measurement region R1 at the irradiation position P30, i.e., the radial direction D2. On the other hand, the reflected light L2 reflected from the irradiation position P30 when the irradiation position P30 is located in the second measurement region R2 is dispersed in multiple directions as shown in (b) of FIG. 3. At this time, most of the reflected light L2 is reflected in a direction different from the radial direction D2 toward the rotation sensor 30. As a result, the amount of light of at least the portion of the reflected light L2 that is directed toward the rotation sensor 30 along the radial direction D2 is smaller than the amount of light of the reflected light L2 when the irradiation position P30 is located in the first measurement region R1.

[0046] Therefore, reflecting the reflected light L2 reflected from the irradiation position P30 when the irradiation position P30 is located in the second measurement region R2 in a direction different from the reflection direction of the reflected light L2 when the irradiation position P30 is located in the first measurement region R1 means changing the reflection direction of some or all of the reflected light L2 from the irradiation position P30 in the second measurement region R2 from the reference direction so that, when the reflection direction of the reflected light L2 from the irradiation position P30 in the first measurement region R1 is taken as the reference direction, the amount of reflected light L2 heading toward the rotation sensor 30 along the reference direction from the irradiation position P30 in the second measurement region R2 is smaller than the amount of reflected light L2 heading toward the rotation sensor 30 along the reference direction.

[0047] In this way, most of the reflected light L2 reflected by the marking M is reflected in a direction different from the radial direction D2 in which the rotation sensor 30 is located, so the amount of reflected light L2 reaching the rotation sensor 30 from the irradiation position P30 when the irradiation position P30 is located in the second measurement region R2 is smaller than the amount of reflected light L2 reaching the rotation sensor 30 from the irradiation position P30 when the irradiation position P30 is located in the first measurement region R1. In this way, the marking M formed in the second measurement region R2 reduces the amount of reflected light L2 reaching the rotation sensor 30, thereby causing a change in the amount of reflected light L2.

[0048] The rotation sensor 30 outputs an electrical signal whose magnitude corresponds to the amount of reflected light L2 from the irradiation position P30. The electrical signal may be, for example, a voltage value or a current value. The greater the amount of reflected light L2, the greater the magnitude of the electrical signal. As described above, when the irradiation position P30 is located in the second measurement region R2, the marking M reduces the amount of reflected light L2 reaching the rotation sensor 30. Therefore, the magnitude of the electrical signal output by the rotation sensor 30 when the irradiation position P30 is located in the second measurement region R2 is smaller than the magnitude of the electrical signal output by the rotation sensor 30 when the irradiation position P30 is located in the first measurement region R1. As a result, the magnitude of the electrical signal output by the rotation sensor 30 decreases each time the second measurement region R2 passes through the irradiation position P30.

[0049] The measuring device 70 measures the rotation speed of the rotating body 10 based on the change in the magnitude of this electrical signal. Specifically, the calculation unit 72 of the measuring device 70 determines whether the magnitude of the electrical signal output from the rotation sensor 30 is smaller than a predetermined threshold. When the calculation unit 72 determines that the magnitude of the electrical signal is smaller than the threshold, it determines that the rotating body 10 has rotated once. The calculation unit 72 calculates the rotation speed of the rotating body 10, for example, by calculating the rotation period based on the number of sampling points per rotation. The method of calculating the rotation speed by the measuring device 70 is not limited to the above calculation method, and other calculation methods may also be used. For example, the calculation unit 72 may calculate the rotation speed of the rotating body 10 by counting the number of times the rotating body 10 rotates once per unit time.

[0050] The following describes the effects of the measurement system 1 and the rotating body 10 of this embodiment, along with the problems inherent in the prior art. Conventionally, various methods have been known for measuring the rotation speed of a rotating body, such as a turbocharger or a gas turbine. For example, a method using a magnetic sensor to measure the rotation speed of a rotating body is known. However, the rotor of the rotating body may be strongly magnetized, and in such cases, the use of a magnetic sensor tends to be avoided. When measuring the rotation speed of a rotating body using a magnetic sensor, the magnetic flux change is detected when the rotating body is rotated with a portion of the rotating body magnetized. The signal output from the magnetic sensor may require processing, such as pulsing. Therefore, when using a magnetic sensor, a dedicated design tailored to the target of the magnetic sensor is required. Therefore, the method using a magnetic sensor has the problem that general-purpose sensors cannot be used.

[0051] On the other hand, sensors other than magnetic sensors can generally be commercially available. In this case, no new design work is required for the sensor. However, for example, when measuring the rotation speed of a rotating body using an optical sensor, a measurement component such as a reflector may be separately attached to the rotating body. Such components can significantly affect the rotational balance of the rotating body. For example, attaching such components to the rotating body may prevent the rotating body from rotating at high speed due to the imbalance in rotation. Another method for measuring rotation speed using an optical sensor involves applying black paint to a single location on the rotating body along its circumference and measuring the rotation speed based on the change in the intensity of the light reflected from the black paint. In this method, the black paint absorbs a portion of the measurement light from the optical sensor, thereby reducing the amount of light reflected from the black paint. Therefore, the amount of reflected light decreases each time the black paint passes the irradiation position of the measurement light. The rotation speed of the rotating body can be measured by detecting the timing at which the amount of reflected light decreases. However, because the black paint is typically applied to the rotating body manually, it is prone to uneven application. Therefore, with this method, the number of rotations of the rotating body may not be measured accurately due to unevenness in the application of the black paint, etc.

[0052] In contrast, the measurement system 1 has a second measurement region R2 on the boss outer peripheral surface 14c that changes the amount of reflected light L2 reaching the rotation sensor 30 from the irradiation position P30. The second measurement region R2 includes a marking M that is processed to reflect the reflected light L2 when the irradiation position P30 is located in the second measurement region R2 in a direction different from the reflection direction of the reflected light L2 when the irradiation position P30 is located in the first measurement region R1. In this case, the reflected light L2 from the irradiation position P30 in the second measurement region R2 can be reflected in a direction different from that of the rotation sensor 30. As a result, the amount of reflected light L2 reaching the rotation sensor 30 from the irradiation position P30 when the irradiation position P30 is located in the second measurement region R2 is smaller than the amount of reflected light L2 reaching the rotation sensor 30 from the irradiation position P30 when the irradiation position P30 is located in the first measurement region R1. Therefore, as the rotating body 10 rotates, the amount of reflected light L2 received by the rotation sensor 30 decreases each time the marking M in the second measurement region R2 passes through the irradiation position P30. The rotation speed of the rotating body 10 can be measured based on this change in the amount of reflected light L2. When the rotating body 10 includes the above-described processed marking M, the rotational balance of the rotating body 10 is less likely to be disrupted than when a separate component for measuring the rotation speed is added to the rotating body 10. Furthermore, since the above-described processed marking M can be formed uniformly and accurately on the boss outer peripheral surface 14c by machining, the risk of inaccurately measuring the rotation speed of the rotating body 10 due to uneven coating, etc., is reduced, unlike when black paint is manually applied to the rotating body 10. Therefore, the above-described measurement system 1 allows the rotation speed of the rotating body 10 to be accurately measured while maintaining the rotational balance of the rotating body 10.

[0053] Graph G1 in FIG. 4A shows the measurement results of the rotation speed of the rotating body 10 measured by the rotation sensor 30 in the measurement system 1. Graph G100 in FIG. 4B shows the measurement results of the rotation speed of the rotating body 10 measured by a magnetic sensor as a reference example. In FIGS. 4A and 4B, the vertical axis represents the rotation speed [rpm] of the rotating body 10 measured using the rotation sensor 30, and the horizontal axis represents the measurement time [sec]. As shown in FIGS. 4A and 4B, it can be seen that graph G1 closely matches graph G100. Therefore, it can be seen from graphs G1 and G100 that the rotation speed of the rotating body 10 can be accurately measured using the rotation sensor 30.

[0054] As in the present embodiment, the marking M may be an unevenly processed portion that has been subjected to uneven processing to diffusely reflect the reflected light L2. In this case, the marking M can be formed on the rotating body 10 by laser processing, in which laser light is irradiated onto the boss outer peripheral surface 14 c of the rotating body 10. When the marking M is formed on the rotating body 10 by laser processing in this manner, the rotational balance of the rotating body 10 is less likely to be disrupted than when the marking M is formed on the rotating body 10 by cutting processing, in which a portion of the boss outer peripheral surface 14 c of the rotating body 10 is removed.

[0055] As in the present embodiment, the rotation sensor 30 may be a laser sensor that irradiates the irradiation position P30 with laser light as the measurement light L1. When a laser sensor is used as the rotation sensor 30 in this way, the distance between the rotation sensor 30 and the rotating body 10 can be made longer than when a proximity sensor is used as the rotation sensor 30. This reduces the risk of interference with other components caused by the rotation sensor 30 being too close to the rotating body 10. As a result, it is possible to avoid the system configuration from becoming complicated in order to avoid interference between the rotation sensor 30 and other components.

[0056] As in this embodiment, the boss outer peripheral surface 14c may be a part of the outer surface of the first impeller 12. The first impeller 12 is generally made of a material that is easier to machine than other components such as the shaft 11. Therefore, the markings M can be easily formed by machining the first impeller 12. Furthermore, unlike the shaft 11, the first impeller 12 is a component that can be removed and replaced from the rotating body 10, making it easy to correct the markings M. Furthermore, when the markings M are formed on the first impeller 12, the effect of the markings M on the rotational balance of the rotating body 10 can be reduced compared to when the markings M are formed on the shaft 11. Furthermore, the first impeller 12 is more likely to be subject to correction for correcting the rotational balance of the rotating body 10, and this correction is performed by machining using the first chuck mechanism 80 and the second chuck mechanism 90. When the markings M are formed on the first impeller 12, the positional relationship between the correction position of the first impeller 12 and the formation position of the markings M can be detected simultaneously by machine. As a result, the modification of the first impeller 12 and the formation of the markings M can be easily performed by machine.

[0057] As in this embodiment, the outer peripheral surface 14c of the boss portion 14 may be the measurement surface onto which the measurement light L1 is irradiated. In this case, the measurement light L1 can be easily irradiated toward the outer peripheral surface 14c from a direction intersecting the rotation axis CL. Furthermore, the boss portion 14 has a lower risk of breakage during high-speed rotation than the hub portion 15, which has multiple blade portions 16 formed thereon, and therefore the marking M can be reliably maintained on the outer peripheral surface 14c of the boss.

[0058] As in this embodiment, the marking M may be formed at a position on the boss outer peripheral surface 14c away from the boundary between the boss portion 14 and the hub portion 15. In this case, it is possible to reduce the risk that the measurement light L1 from the rotation sensor 30 will be irradiated by mistake onto the plurality of blades 16 formed on the hub portion 15. Furthermore, in this case, even if the rotation sensor 30 is disposed at a position close to the boss outer peripheral surface 14c, it is possible to reduce the risk that the rotation sensor 30 will interfere with the plurality of blades 16 of the hub portion 15.

[0059] The measurement system and rotating body of the present disclosure are not limited to the above-described embodiments. The specific aspects of the measurement system and rotating body of the present disclosure may be appropriately modified without departing from the spirit of the claims.

[0060] <Modification 1> Figures 5(a) to 5(c) show a rotating body 10A according to Modification 1. In place of the above-described marking M, a marking MA is formed in the second measurement region R2 of the rotating body 10A. The marking MA is an inclined surface formed by mechanically chamfering the boss outer peripheral surface 14c of the boss portion 14A. The marking MA is formed on the boss outer peripheral surface 14c in the same area and shape as the above-described marking M, for example.

[0061] 5C, the marking MA, which is configured as an inclined surface, extends in a direction different from the axial direction D1 along which the first measurement region R1 extends in a cross section including the rotation axis CL. Specifically, the marking MA extends in a direction inclined with respect to the rotation axis CL so as to approach the rotation axis CL as it approaches the first boss end face 14a. As a result, the normal direction of the marking MA is inclined with respect to the normal direction of the first measurement region R1. In other words, the normal direction of the marking MA is inclined with respect to the radial direction D2, which is the optical axis direction of the rotation sensor 30.

[0062] The inclination angle θA of the extension direction of the marking MA with respect to the axial direction D1 of the rotation axis CL is, for example, 5 degrees or more and 30 degrees or less. The inclination angle θA may be, for example, 5 degrees or more and 10 degrees or less. In (c) of FIG. 5, for example, the width d1 of the boss portion 14A in the axial direction D1 is 3 mm, and the diameter d2 of the boss portion 14A is 20 mm. The width d3 of the marking MA in the axial direction D1 is, for example, 0.9 mm or more and 1.7 mm or less. The depth d4 of the marking MA in the radial direction D2 from the boss outer peripheral surface 14c is, for example, 0.5 mm or more and 1 mm or less.

[0063] 6A, when the irradiation position P30 is located in the first measurement region R1 configured as the smooth boss outer peripheral surface 14c, the normal direction of the first measurement region R1 at the irradiation position P30 coincides with the optical axis direction of the rotation sensor 30. Therefore, the measurement light L1 irradiated from the rotation sensor 30 along the radial direction D2 to the irradiation position P30 of the first measurement region R1 is reflected from the irradiation position P30 toward the rotation sensor 30 along the radial direction D2. In other words, the reflection direction of the reflected light L2 in the first measurement region R1 coincides with the irradiation direction of the measurement light L1 from the rotation sensor 30.

[0064] 6B, when the irradiation position P30 is located in the second measurement region R2 where the marking MA is formed, the normal direction of the marking MA is different from the optical axis direction of the rotation sensor 30, which is along the radial direction D2, and therefore most of the reflected light L2 reflected by the marking MA is reflected in a direction different from the radial direction D2 in which the rotation sensor 30 is located. As a result, the amount of reflected light L2 reaching the rotation sensor 30 from the irradiation position P30 when the irradiation position P30 is located in the second measurement region R2 is smaller than the amount of reflected light L2 reaching the rotation sensor 30 from the irradiation position P30 when the irradiation position P30 is located in the first measurement region R1. In this way, the marking MA reduces the amount of reflected light L2 reaching the rotation sensor 30.

[0065] Therefore, the rotating body 10A with the marking MA formed thereon achieves the same effect as the rotating body 10 with the marking M formed thereon. Furthermore, since the marking MA on the rotating body 10A is an inclined surface extending in a direction different from the axial direction D1 along which the first measurement region R1 extends, the marking M can be easily formed on the rotating body 10 by simply chamfering a portion of the boss outer peripheral surface 14c of the rotating body 10. Graph G2 in FIG. 7A shows the measurement results of the rotation speed of the rotating body 10A measured by the rotation sensor 30. Graph G200 in FIG. 7B shows the measurement results of the rotation speed of the rotating body 10A measured by a magnetic sensor as a reference example. As shown in FIGS. 7A and 7B, it can be seen that the graph G2 closely matches the graph G200. Therefore, it can be seen from the graphs G2 and G200 that the rotation speed of the rotating body 10A can be accurately measured using the rotation sensor 30.

[0066] <Modification 2> Fig. 8 shows a measurement system 1A equipped with a rotating body 10B of modification 2. The measurement system 1A is equipped with a rotating body 10B instead of the above-described rotating body 10. The configuration of the measurement system 1A other than the rotating body 10B is the same as that of the above-described measurement system 1. In addition to the configuration of the above-described rotating body 10, the rotating body 10B is equipped with a nut 17.

[0067] The nut 17 is a component for attaching the first impeller 12 to the shaft 11. The nut 17 has a cylindrical shape centered on the rotation axis CL. The nut 17 includes, for example, a first nut end face 17a, a second nut end face 17b, and a nut outer circumferential surface 17c (measurement surface). The first nut end face 17a and the second nut end face 17b are aligned in the axial direction D1. The shaft end face 11c protrudes from the first nut end face 17a. The second nut end face 17b is in contact with the boss portion 14 in the axial direction D1. The nut outer circumferential surface 17c is the outer circumferential surface of the nut 17 extending along the circumferential direction D3. The nut outer circumferential surface 17c connects the first nut end face 17a and the second nut end face 17b in the axial direction D1. The nut outer circumferential surface 17c is, for example, a circumferential surface centered on the rotation axis CL.

[0068] In the rotating body 10B, the nut outer peripheral surface 17c is configured as a measurement surface onto which measurement light L1 is irradiated to measure the rotation speed of the rotating body 10. A rotation sensor 30 is disposed at a position facing the nut outer peripheral surface 17c in the radial direction D2. The rotation sensor 30 irradiates the measurement light L1 toward the nut outer peripheral surface 17c. A marking MB is formed on the nut outer peripheral surface 17c. The marking MB has, for example, the same configuration as the marking M described above. Even with this configuration, the same effects as those of the above-described embodiment can be achieved.

[0069] <Modification 3> FIG. 9 shows a measurement system 1B including a rotating body 10C according to Modification 3. The measurement system 1B includes a rotating body 10C instead of the rotating body 10 described above. The rotating body 10C includes a nut 17 in addition to the components of the rotating body 10. Furthermore, in the rotating body 10C, a marking MC is formed on the shaft end surface 11c (measurement surface). The rotation sensor 30 is disposed in a position facing the shaft end surface 11c in the axial direction D1. The rotation sensor 30 emits measurement light L1 in the axial direction D1 toward the shaft end surface 11c. In this case, the optical axis direction of the rotation sensor 30 coincides with the axial direction D1. In consideration of the presence of the first chuck mechanism 80 shown in FIG. 1 in this configuration, a through-hole through which the measurement light L1 passes may be formed in the first chuck mechanism 80 to prevent the measurement light L1 from being obstructed by the first chuck mechanism 80.

[0070] 10A, when the shaft end surface 11c is viewed in the axial direction D1 along which the rotation axis CL extends, the shaft end surface 11c includes a first measurement region R1 and a second measurement region R2 adjacent to each other along the circumferential direction D3. The first measurement region R1 is a region on one side of the shaft end surface 11c when the shaft end surface 11c is cut in half by a plane including the rotation axis CL. The second measurement region R2 is a region on the other side of the shaft end surface 11c when the shaft end surface 11c is cut in half by a plane including the rotation axis CL. The marking MC formed in the second measurement region R2 has, for example, the same configuration as the marking M described above.

[0071] As shown in (a) of FIG. 10 , when the irradiation position P30 is located in the first measurement region R1, the measurement light L1 irradiated from the rotation sensor 30 along the axial direction D1 to the irradiation position P30 in the first measurement region R1 is reflected from the irradiation position P30 toward the rotation sensor 30 along the axial direction D1. On the other hand, as shown in (b) of FIG. 10 , when the irradiation position P30 is located in the second measurement region R2 where the marking MC is formed, most of the reflected light L2 reflected by the marking MC is reflected in a direction different from the axial direction D1 in which the rotation sensor 30 is located. Therefore, when the irradiation position P30 is located in the second measurement region R2, the amount of reflected light L2 reaching the rotation sensor 30 from the irradiation position P30 is smaller than the amount of reflected light L2 reaching the rotation sensor 30 from the irradiation position P30 when the irradiation position P30 is located in the first measurement region R1. Even with this configuration, the same effects as those of the above-described embodiment can be achieved.

[0072] <Modification 4> Figure 11 shows a measurement system 1C including a rotating body 10D of modification 4. The measurement system 1C includes the rotating body 10D instead of the rotating body 10 described above. Like the rotating body 10B, the rotating body 10D includes a nut 17. Like the rotating body 10, the rotating body 10D has a marking M formed on the boss portion 14. Furthermore, the measurement system 1C includes a rotation sensor 31 (optical sensor) instead of the rotation sensor 30 described above.

[0073] The rotation sensor 31 is a proximity sensor located close to the boss portion 14 of the rotating body 10D. The distance in the radial direction D2 from the rotation sensor 31 to the irradiation position P31, i.e., the detection distance of the rotation sensor 31, is, for example, in the range of greater than 0 μm and less than 60 mm. The detection distance of the rotation sensor 31 may be, for example, in the range of greater than 250 μm and less than 60 mm. Even if the rotation sensor 31 is equipped with a long-distance focusing lens, it needs to be located closer to the rotating body 10D than the rotation sensor 30 serving as the laser sensor described above. Therefore, the measurement system 1C requires a mechanism to prevent the rotation sensor 31 from interfering with other components, such as the first impeller 12 and the first chuck mechanism 80 (see FIG. 1 ).

[0074] The rotation sensor 31 may be, for example, an optical fiber sensor that emits measurement light L1. In this case, the measurement light L1 is emitted from the optical fiber and irradiated onto the boss portion 14 in the radial direction D2. The rotation sensor 31 includes, for example, a sensor head 31a that irradiates the irradiation position P31 with the measurement light L1 and acquires the amount of reflected light L2 as an electrical signal φ3a, and a sensor amplifier 31b that amplifies the electrical signal φ3a from the sensor head 31a. The rotation sensor 31 transmits the electrical signal φ31 amplified by the sensor amplifier 31b to the measuring device 70 as a detection result indicating the amount of reflected light L2. Even in this configuration, the same effects as those of the above-described embodiment can be achieved.

[0075] <Additional Notes> The present disclosure is [1] "a measurement system comprising: a rotating body including a shaft rotatable around a rotation axis; an optical sensor arranged at a position facing a measurement surface that is a part of the outer surface of the rotating body, and configured to irradiate measurement light onto the measurement surface and receive reflected light of the measurement light reflected from the measurement surface; and a measurement device communicably connected to the optical sensor and measuring the number of rotations of the rotating body based on a change in the state of the reflected light that reaches the optical sensor from the measurement surface, wherein the measurement surface includes: a first measurement area that reflects the reflected light toward the optical sensor; and a second measurement area that is adjacent to the first measurement area in the circumferential direction of the rotation axis and passes through an irradiation position of the measurement light on the measurement surface every time the rotating body makes one revolution around the rotation axis, and the second measurement area includes a marking that is processed to reflect the reflected light when the irradiation position is located in the second measurement area in a direction different from the reflection direction of the reflected light when the irradiation position is located in the first measurement area."

[0076] The present disclosure is [2] "The measurement system described in the above [1], wherein the marking is a textured portion that is textured to diffuse reflected light."

[0077] The present disclosure is [3] "The measurement system described in [1] above, wherein the marking is an inclined surface extending in a direction different from the direction in which the first measurement area extends in a cross section including the rotation axis."

[0078] The present disclosure is [4] "A measurement system according to any one of [1] to [3] above, wherein the optical sensor is a laser sensor that irradiates the irradiation position with laser light as the measurement light."

[0079] The present disclosure further provides, [5] "The measurement system according to any one of the above [1] to [4], wherein the rotating body further includes an impeller attached to the shaft, and the measurement surface is a part of an outer surface of the impeller.

[0080] The present disclosure is [6] "The measurement system described in the above [5], wherein the impeller includes a cylindrical boss portion through which the shaft passes, a hub portion extending from the boss portion along the radial direction of the rotation axis and the circumferential direction, and a plurality of blade portions rising from the hub portion, the boss portion including a boss outer peripheral surface extending along the circumferential direction, and the measurement surface being the boss outer peripheral surface."

[0081] The present disclosure is [7] "The measurement system described in [6] above, wherein the marking is formed at a position on the outer peripheral surface of the boss away from the boundary between the boss portion and the hub portion."

[0082] The present disclosure is [8] "a rotating body including a shaft rotatable around a rotation axis, wherein measurement light is irradiated from an optical sensor onto a measurement surface that is a part of the outer surface of the rotating body, the measurement surface including: a first measurement area that reflects reflected light of the measurement light toward the optical sensor; and a second measurement area that is adjacent to the first measurement area in the circumferential direction of the rotation axis and passes through an irradiation position of the measurement light on the measurement surface every time the rotating body rotates once around the rotation axis, the second measurement area including a marking that has been processed to reflect the reflected light when the irradiation position is located in the second measurement area in a direction different from the reflection direction of the reflected light when the irradiation position is located in the first measurement area."

[0083] 1, 1A, 1B, 1C Measurement system 10, 10A, 10B, 10C, 10D Rotating body 11 Shaft 11c Shaft end face (measurement surface) 14, 14A Boss portion 14c Boss outer peripheral surface (measurement surface) 15 Hub portion 16 Blade portion 17c Nut outer peripheral surface (measurement surface) 30, 31 Rotation sensor (optical sensor) 70 Measuring device CL Rotation axis D2 Radial direction D3 Circumferential direction L1 Measurement light L2 Reflected light M, MA, MB, MC Markings P30, P31 Irradiation position R1 First measurement area R2 Second measurement area

Claims

1. A measurement system comprising: a rotating body including a shaft rotatable around a rotation axis; an optical sensor arranged at a position facing a measurement surface which is a part of the outer surface of the rotating body, irradiating measurement light onto the measurement surface and receiving reflected light of the measurement light reflected from the measurement surface; and a measurement device connected to the optical sensor so as to be able to communicate with the optical sensor and measuring the number of rotations of the rotating body based on a change in the state of the reflected light which reaches the optical sensor from the measurement surface, wherein the measurement surface includes: a first measurement area which reflects the reflected light towards the optical sensor; and a second measurement area which is adjacent to the first measurement area in the circumferential direction of the rotation axis and passes through an irradiation position of the measurement light on the measurement surface each time the rotating body makes one revolution around the rotation axis, and the second measurement area includes a marking which has been processed to reflect the reflected light when the irradiation position is located in the second measurement area in a direction different from the reflection direction of the reflected light when the irradiation position is located in the first measurement area.

2. The measurement system according to claim 1, wherein the marking is a textured portion that is textured to diffuse reflected light.

3. The measurement system according to claim 1, wherein the marking is an inclined surface extending in a direction different from the direction in which the first measurement area extends in a cross section including the rotation axis.

4. A measurement system according to any one of claims 1 to 3, wherein the optical sensor is a laser sensor that irradiates the irradiation position with laser light as the measurement light.

5. A measurement system according to any one of claims 1 to 3, wherein the rotating body further includes an impeller attached to the shaft, and the measurement surface is a part of an outer surface of the impeller.

6. The measurement system described in claim 5, wherein the impeller includes a cylindrical boss portion through which the shaft passes, a hub portion extending from the boss portion in a radial direction of the rotation axis and in the circumferential direction, and a plurality of blade portions rising from the hub portion, the boss portion including a boss outer peripheral surface extending in the circumferential direction, and the measurement surface being the boss outer peripheral surface.

7. The measurement system according to claim 6, wherein the marking is formed on the outer peripheral surface of the boss at a position away from the boundary between the boss portion and the hub portion.

8. A rotating body including a shaft rotatable about a rotation axis, wherein a measurement light is irradiated from an optical sensor onto a measurement surface which is a part of the outer surface of the rotating body, the measurement surface including: a first measurement area which reflects reflected light of the measurement light toward the optical sensor; and a second measurement area which is adjacent to the first measurement area in the circumferential direction of the rotation axis and passes through an irradiation position of the measurement light on the measurement surface each time the rotating body rotates once about the rotation axis, the second measurement area including a marking which is processed to reflect the reflected light when the irradiation position is located in the second measurement area in a direction different from the reflection direction of the reflected light when the irradiation position is located in the first measurement area.

Images