Rotation measuring device

Abstract

To detect a physical quantity correlated with angular acceleration of a rotating shaft using a retrofittable rotation measuring device.SOLUTION: A sub-base 12 is bound to a main base 11 in which a rotating shaft 500 is inserted into a hollow section 111, and a rotation detector 1 is fixed to the rotating shaft 500. A first acceleration sensor 161 and a second acceleration sensor 162 that respectively detect acceleration in a tangential direction of a circle centered on a set axis C passing through the positions with a direction heading to a same rotational direction as a positive direction are provided at the two positions on the main base 11 which are line-symmetrical with respect to the set axis C overlapping with a rotational center axis of the rotating shaft 500 in the time of fixation. 1 / 2 of an addition value of the output of the first acceleration sensor 161 and the second acceleration sensor 162 is detected as tangential acceleration due to angular acceleration of the rotating shaft 500.SELECTED DRAWING: Figure 5

Description

[Technical field]

[0001] The present invention relates to a technique for detecting a physical quantity that correlates with the angular acceleration of a rotating shaft. [Background technology]

[0002] As a technique for detecting the angular acceleration of a rotating shaft, a technique is known in which the angular acceleration of an electric motor of an electric vehicle is detected by differentiating the rotation speed of the electric motor (for example, see Patent Document 1). Furthermore, a technique is known in which the rotation speed of an electric motor in an electric vehicle is detected by using an encoder that outputs a pulse for each predetermined rotation angle (for example, Patent Document 2). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2013-110927 A [Patent Document 2] Japanese Patent Application Publication No. 11-205915 Summary of the Invention [Problem to be solved by the invention]

[0004] The electric motor of an electric vehicle has a better response than an internal combustion engine, and when detecting angular acceleration by differentiating the rotation speed detected by a general rotation sensor equipped in the electric motor, the time resolution may not be sufficient for measurement applications such as testing and performance evaluation. Also, when the above-mentioned encoder is used as a rotation sensor, the time interval of the pulse output may exceed the limit when driving at low speeds of a few km / h or less (at low rotation speeds), and the rotation speed itself may not be detected correctly.

[0005] Therefore, for such electric vehicles, it is desirable to have a rotation detection device that can be retrofitted to measure a physical quantity that correlates with angular acceleration with a required time resolution and measurement range. Therefore, an object of the present invention is to provide a rotation measuring device that can be retrofitted and that can detect a physical quantity that correlates with the angular acceleration of a rotating shaft with high time resolution even at low rotation speeds. [Means for solving the problem]

[0006] In order to achieve the above object, the present invention provides a rotation measuring device for measuring the rotation of a rotating shaft, the device comprising a main base, a sub-base capable of being fastened to the main base, a first acceleration sensor fixed to the main base, and a second acceleration sensor fixed to the main base. Here, the main base and the sub-base are fastened to each other so as to sandwich the rotating shaft in the radial direction of the rotating shaft, so that the main base and the sub-base have shapes in which a set axis, the relative position of which with respect to the main base is fixed, coincides with the rotation center axis of the rotating shaft. The first acceleration sensor and the second acceleration sensor are disposed at positions that are linearly symmetrical with respect to the set axis of the main base. The first acceleration sensor detects an acceleration in a tangent direction of a circle centered on the set axis and passing through the first acceleration sensor as a first tangential acceleration, and the second acceleration sensor detects an acceleration in a tangent direction of the circle and passing through the second acceleration sensor as a second tangential acceleration.

[0007] Furthermore, this rotation measuring device may include one or more first clamping members attached to the main base, the first clamping members having ends that abut against the outer circumferential surface of the rotating shaft when fastened between the main base and the sub-base, and one or more second clamping members attached to the sub-base, the second clamping members having ends that abut against the outer circumferential surface of the rotating shaft when fastened between the main base and the sub-base. Here, the main base and the sub-base clamp the rotating shaft in the radial direction of the rotating shaft by the abutment of the ends of the first clamping members with the outer circumferential surface of the rotating shaft and the abutment of the ends of the second clamping members with the outer circumferential surface of the rotating shaft. In addition, the first clamping member is replaceably attached to the main base, and the distance from the end of the first clamping member to the set axis can be changed by replacing the first clamping member, and the second clamping member is replaceably attached to the sub-base, and the distance from the end of the second clamping member to the set axis when the main base and the sub-base are fastened to each other can be changed by replacing the second clamping member.

[0008] Furthermore, in the above rotation measuring device, the shape of the main base has a rotating shaft accommodating space which is formed by a recess in a direction perpendicular to the set axis and which includes the set axis therein, and both sides of the recess include positions which are linearly symmetrical with respect to the set axis and in which the first acceleration sensor and the second acceleration sensor are arranged, and with the rotating shaft accommodated in the rotating shaft accommodating space of the main base, the sub-base may be fastened to the main base so as to cover an opening of the rotating shaft accommodating space.

[0009] In this case, the above-mentioned first clamping member may be attached so that its end protrudes from the surface of the main base facing the rotating shaft accommodating space, and the second clamping member may be attached so that its end protrudes from the surface of the main base facing the rotating shaft accommodating space when the main base and the sub-base are fastened together.

[0010] The above rotation measurement device may further include a rotation detection means. In this case, the second acceleration sensor detects an acceleration in the direction of a tangent to the circle passing through the second acceleration sensor, the acceleration being the same in the same circumferential direction as the first tangential acceleration, and the rotation detection means calculates an acceleration obtained by adding the first tangential acceleration and the second tangential acceleration as the detected tangential acceleration.

[0011] Alternatively, the above rotation measurement device may be provided with an adjustment means, an adjustment amount setting means, and a rotation detection means. In this case, the second acceleration sensor detects an acceleration in the same circumferential direction as the first tangential acceleration, the positive and negative of which are the same as the first tangential acceleration in the direction of a tangent of the circle passing through the second acceleration sensor, as the second tangential acceleration. The adjustment means adjusts at least one of the first tangential acceleration and the second tangential acceleration with a set gain and offset and outputs the adjusted acceleration. The adjustment amount setting means sets the gain and offset so that the sum of the first tangential acceleration and the second tangential acceleration output from the adjustment means becomes 0 when the angular acceleration of the rotating shaft is 0. The rotation detection means calculates the acceleration obtained by adding the first tangential acceleration and the second tangential acceleration output from the adjustment means as the detected tangential acceleration.

[0012] Furthermore, the rotation detection means may further calculate the angular acceleration of the rotating shaft by dividing the detected tangential acceleration by a radius of the circle. According to the rotation measurement device as described above, the first acceleration sensor and the second acceleration sensor are fixed to the integrated main base. The first acceleration sensor and the second acceleration sensor are arranged at positions that are symmetrical with respect to a set axis that coincides with the central axis of rotation of the rotating shaft when the main base and the sub-base are fastened and fixed to the rotating shaft.

[0013] Therefore, in a configuration that can be retrofitted to a rotating shaft, the first acceleration sensor and the second acceleration sensor can be fixed with high precision at positions that are line-symmetrical with respect to the central axis of rotation of the rotating shaft. Here, a physical quantity that correlates with the angular acceleration of the rotating shaft, such as tangential acceleration due to angular acceleration, can be calculated from the acceleration at two positions that are linearly symmetrical with respect to the central axis of rotation. Therefore, by precisely fixing the first and second acceleration sensors at the linearly symmetrical positions, it is possible to accurately measure the physical quantity that correlates with angular acceleration.

[0014] For example, when the rotation detection means is provided as described above and the acceleration obtained by adding the first tangential acceleration detected by the first acceleration sensor and the second tangential acceleration detected by the second acceleration sensor is calculated as the detected tangential acceleration, the tangential acceleration due to the angular acceleration of the rotating shaft can be accurately measured without the influence of gravity or external forces. Also, the influence of the deviation of the setting axis from the central axis of rotation of the rotating shaft can be eliminated.

[0015] Furthermore, if the rotation detection means calculates the angular acceleration of the rotating shaft by dividing the detected tangential acceleration by the radius of the circle, it is possible to accurately measure the angular acceleration of the rotating shaft while eliminating the effects of gravity and external forces. Furthermore, by detecting the tangential acceleration and angular acceleration due to the angular acceleration of the rotating shaft from the tangential acceleration in this way, it is possible to detect a physical quantity correlated with the angular acceleration of the rotating shaft with higher time resolution even at low rotation speeds, compared to when angular acceleration is detected by differentiating the rotation speed detected by a rotation sensor.

[0016] Furthermore, when the first clamping member of the main base and the second clamping member of the sub-base are provided interchangeably, the rotation measuring device can be applied to rotating shafts of different diameters. Next, in order to achieve the above object, the present invention provides a rotation measuring device for measuring the rotation of a rotating shaft, comprising: a base detachably fixed to the rotating shaft so as to rotate together with the rotating shaft; a first acceleration sensor fixed to the base; a second acceleration sensor fixed to the base; and a rotation detection means. The base is fixed to the rotating shaft so that a set axis, the relative position of which with respect to the base is fixed, coincides with the rotation center axis of the rotating shaft, and the first acceleration sensor and the second acceleration sensor are arranged at positions that are linearly symmetrical with respect to the set axis. The first acceleration sensor detects an acceleration in a tangent direction of a circle centered on the set axis that passes through the first acceleration sensor as a first tangential acceleration, detects a radial acceleration of the circle passing through the first acceleration sensor as a first radial acceleration, and the second acceleration sensor detects an acceleration in a radial direction of the circle passing through the second acceleration sensor, the positive and negative of which are the same as the first radial acceleration, as a second radial acceleration. Then, when the base is fixed to the rotating shaft, the rotation detection means performs a correction to remove the influence of deviation of the central axis of rotation of the rotating shaft from the set axis on the tangential acceleration component due to the angular acceleration of the rotating shaft contained in the first tangential acceleration, in accordance with the ratio between the first radial acceleration and the second radial acceleration.

[0017] Here, this rotation measurement device is configured so that the second acceleration sensor detects an acceleration in the direction of a tangent to the circle passing through the second acceleration sensor, the acceleration being the same as the first tangential acceleration in the same circumferential direction and having a positive or negative sign, and the rotation detection means detects a tangential acceleration a due to the angular acceleration of the rotating shaft by defining the first tangential acceleration as SA, the second tangential acceleration as SB, the first radial acceleration as DA, the second radial acceleration as DB, the radius of the circle as r, a tangential acceleration component due to the angular acceleration of the rotating shaft in the first tangential acceleration SA as aA, and a tangential acceleration component due to the angular acceleration of the rotating shaft in the first tangential acceleration SB as aB, and calculates a tangential acceleration a due to the angular acceleration of the rotating shaft by KD=DA / DB, dx = {(1-KD)·r} / (1+KD) KA=r / (r-dx) KB=r / (r+dx) As, aA=(SA+SB) / {(1 / KD)+1)} aB = (SA + SB) / (1 + KD) a = {(KA aA) + (KB aB)} / 2 or, a = {(KA SA) + (KB SB)} / 2 It may also be calculated by:

[0018] With such a rotation measurement device, it is also possible to perform measurements that eliminate the influence of deviation of the rotation center axis of the rotating shaft from the set axis. In this rotation measurement device, the rotation detection means may also calculate the angular acceleration of the rotating shaft by dividing the tangential acceleration a by the radius of the circle. Effect of the Invention

[0019] As described above, according to the present invention, it is possible to provide a rotation measurement device that can be retrofitted and that can detect a physical quantity that correlates with the angular acceleration of a rotating shaft with high time resolution even at low rotation speeds. [Brief description of the drawings]

[0020] [Figure 1] FIG. 2 is a diagram showing a configuration of a rotation detector according to an embodiment of the present invention. [Diagram 2] 1A and 1B are diagrams illustrating a fixing method of a rotation detector according to an embodiment of the present invention. [Diagram 3] 11A and 11B are diagrams illustrating a method for dealing with differences in diameter of a rotating shaft of a rotation detector according to an embodiment of the present invention. [Figure 4] 1 is a diagram showing a configuration of a rotation measurement system using a rotation detector according to an embodiment of the present invention. [Diagram 5] FIG. 2 is a diagram showing acceleration detected by an acceleration sensor according to an embodiment of the present invention. [Figure 6] FIG. 11 is a diagram showing another example of the configuration of a rotation measurement system using a rotation detector according to an embodiment of the present invention. [Figure 7] 11A and 11B are diagrams illustrating another example of the configuration of a rotation detector according to an embodiment of the present invention. [Figure 8] 11A and 11B are diagrams illustrating another example of the configuration of a rotation detector according to an embodiment of the present invention. [Figure 9] 11A and 11B are diagrams illustrating another example of the configuration of a rotation detector according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0021] Hereinafter, an embodiment of the present invention will be described. First, the first embodiment will be described. The configuration of the rotation detector is shown in Figure 1a-f. For convenience, the front, back, top, bottom, left and right of the rotation detector 1 are defined as shown in the figures, with Fig. 1a showing the top surface of the rotation detector 1, Fig. 1b showing the front surface of the rotation detector 1, Fig. 1c showing the left side surface of the rotation detector 1, Fig. 1d showing the right side surface of the rotation detector 1, Fig. 1e showing the bottom surface of the rotation detector 1, and Fig. 1f showing a perspective view of the rotation detector 1. The rear surface of the rotation detector 1 appears symmetrical to the front surface.

[0022] As shown in the figure, the rotation detector 1 has a rigid, integral main base 11 and a sub-base 12 connected to the lower part of the main base 11. The main base 11 and the sub-base 12 are connected by a hinge 13 provided at the lower right end of the main base 11, which rotatably connects the right end of the sub-base 12, and a screw 14 that vertically connects the left end of the sub-base 12 to the lower left end of the main base 11. The main base 11 has an inner surface that forms a hollow portion 111 (recess) that penetrates in the front-rear direction and has an opening that opens downward. The inner surface of the main base 11 is shaped so that the width in the left-right direction of the hollow portion 111 is equal and maximum at least in the range from the lowest position where it is open to the position of the set shaft height that is set at a predetermined height in the up-down direction of the hollow portion 111. In addition, the shape of the left and right inner surfaces of the main base 11 in the range above the position of the set shaft height or a position slightly higher than the position of the set shaft height is a tapered shape that narrows toward the center in the left-right direction.

[0023] First mounting grooves 112 extending in the front-rear direction are provided in the tapered portions of the left and right inner surfaces of the main base 11, and a clamping block 15 is detachably mounted in each of the first mounting grooves 112 with the clamping block 15 protruding inward from the inner surface. A second mounting groove 121 extending in the front-rear direction is provided in the upper surface of the sub-base 12, and a clamping block 15 is detachably mounted in the second mounting groove 121 with the clamping block 15 protruding upward from the upper surface.

[0024] Here, a set axis C having an axial direction in the front-rear direction is set in advance for the rotation detector 1, and the set axis C is an axis that is equidistant from the surface facing inward of the hollow portion 111 of each clamping block 15 when the sub-base 12 is fastened to the main base 11 with the screws 14. The vertical height of the set axis C is the set axis height described above.

[0025] Next, a first acceleration sensor 161 and a second acceleration sensor 162 are fixed at positions at the set axis height on the left and right sides of the main base 11 outside the hollow portion 111 so that the distances to the set axis C are equal. Therefore, the first acceleration sensor 161 and the second acceleration sensor 162 are arranged at positions that are line-symmetrical with respect to the set axis C (positions that are point-symmetrical with respect to the set axis C when viewed in the axial direction).

[0026] Next, the rotation detector 1 is fixed to a rotating shaft to be measured before use. The fixing to the rotating shaft is performed by opening the hinge 13 as shown in Figure 2a, inserting the rotating shaft 500 so that it covers the hollow section 111 of the main base 11, and then closing the hinge 13 as shown in Figure 2b and fastening the sub-base 12 to the main base 11 with screws 14, and clamping the rotating shaft 500 with three clamping blocks 15 as shown in Figures 2c and 2d.

[0027] Here, with the rotation detector 1 fixed to the rotating shaft 500 in this manner, the central axis of rotation of the rotating shaft 500 is equidistant from the inward-facing surfaces of the hollow portions 111 of each clamping block 15 and coincides with the set axis C described above. Next, as described above, the three clamping blocks 15 are detachably attached to the main base 11 and the sub-base 12. As shown in Figures 3a, 3b and 3c, by replacing the clamping block 15 with one having a different length in the direction toward the set axis C to match the diameter of the rotating shaft 500, the rotation detector 1 can be fixed and used on rotating shafts 500 of different diameters. Next, a rotation measurement system configured using such a rotation detector 1 will be described. Figure 4 shows the functional configuration of the signal processing system of the rotation measurement system. As shown in the figure, the rotation measurement system includes a rotation detector 1 and a calculation device 2. In addition to the first acceleration sensor 161 and second acceleration sensor 162 described above, the rotation detector 1 includes a gain / offset adjustment unit 101, an adder unit 102, an analog-to-digital converter 103 (A / D), and a wireless interface 104 (wireless IF), which are not shown in FIG. 1-3. Gain / offset adjustment unit 101 adjusts the gain and offset of the output of first acceleration sensor 161 and outputs the result to addition unit 102. Addition unit 102 adds the output of gain / offset adjustment unit 101 and the output of second acceleration sensor 162 and transmits the result to analog-digital converter 103, which converts the output of addition unit 102 into a digital signal, and wireless interface 104 wirelessly transmits the output of analog-digital converter 103 to calculation device 2 as detection data.

[0028] Next, the arithmetic device 2 includes a wireless communication unit 201, an arithmetic processing unit 202, a digital-to-analog converter (D / A) 203, and a control unit 204 that controls the entire rotation measurement system. The wireless communication unit 201 receives detection data from the rotation detector 1 via wireless communication and sends it to the calculation processing unit 202. The calculation processing unit 202 performs a predetermined calculation process on the detection data sent from the wireless communication unit 201 to generate digital measurement data. The details of the calculation process performed by the calculation processing unit 202 will be described later.

[0029] Then, the calculation processing unit 202 outputs the generated digital measurement data as a digital measurement signal DO to a device external to the calculation device 2. The digital-to-analog converter 203 converts the digital measurement data generated by the calculation processing unit 202 into analog data and outputs it to a device external to the calculation device 2 as an analog measurement signal AO.

[0030] In addition, the control unit 204 performs an operation of controlling the execution of a calibration operation for adjusting the gain and offset in the gain / offset adjustment unit 101 via the wireless communication unit 201 and the wireless interface 104 of the rotation detector 1, as well as other control operations. The operation of signal processing in such a rotation measurement system will now be described in detail. First, the first acceleration sensor 161 and the second acceleration sensor 162 are uniaxial acceleration sensors, and a capacitance-type MEMS sensor can be used as such a uniaxial acceleration sensor. Generally, a capacitance-type acceleration sensor can also detect the acceleration of a DC component. However, other types of acceleration sensors according to the purpose of measurement may be used as the first acceleration sensor 161 and the second acceleration sensor 162. For example, in a purpose requiring a high resolution of the magnitude of acceleration, a piezoelectric acceleration sensor or the like may be used. Next, as shown in FIG. 5a, the first acceleration sensor 161 is oriented to detect acceleration SA in the detection axis direction, with the detection axis being an axis tangential to a circle centered on the set axis C and passing through the first acceleration sensor 161, and the second acceleration sensor 162 is oriented to detect acceleration SB applied in the detection axis direction, with the detection axis being an axis tangential to a circle centered on the set axis C and passing through the second acceleration sensor 162.

[0031] Here, in the state where the rotation detector 1 is fixed to the rotating shaft 500 as described above, the central axis of rotation of the rotating shaft 500 coincides with the set axis C. Therefore, with the rotation detector 1 fixed to the rotating shaft 500, the positions of the first acceleration sensor 161 and the second acceleration sensor 162 are linearly symmetrical with respect to the central axis of rotation of the rotating shaft 500, and the angular difference between the first acceleration sensor 161 and the second acceleration sensor 162 in the rotational direction of the rotating shaft 500 as viewed from the central axis of the rotating shaft 500 is 180°. The first acceleration sensor 161 and the second acceleration sensor 162 detect acceleration in the tangential direction of the same circle centered on the central axis of the rotating shaft 500.

[0032] In addition, in FIG. 5a, as indicated by the positive arrow with a "+" mark, the positive direction of acceleration SA detected by first acceleration sensor 161 and the positive direction of acceleration SB detected by second acceleration sensor 162 are set in the direction of a tangent toward the same circumferential direction, and are mutually opposite directions when viewed from a fixed system that does not rotate together with rotating shaft 500 and is a system fixed with respect to the Earth.

[0033] Furthermore, as shown in FIG. 5b, if the tangential acceleration applied to the first acceleration sensor 161 and the second acceleration sensor 162 due to the angular acceleration of the rotating shaft 500 is represented by a, the gravitational acceleration is represented by g, the acceleration applied to the rotating shaft 500 due to a disturbance in a direction perpendicular to the central axis of rotation of the rotating shaft 500 is represented by b, the positive component of the gravitational acceleration g in the detection axis of the first acceleration sensor 161 is represented by gx, and the positive component of the acceleration b due to the disturbance in the detection axis of the first acceleration sensor 161 is represented by bx, then when the rotating shaft 500 has rotated by θ from an angle where the left-right direction of the rotation detector 1 is the horizontal direction of the fixed system (direction perpendicular to the gravitational acceleration) when viewed from the fixed system, the acceleration SA detected by the first acceleration sensor 161 and the acceleration SB detected by the second acceleration sensor 162 can be expressed by the following equation when the gains and offsets of the first acceleration sensor 161 and the second acceleration sensor 162 are equal.

[0034] SA=a+gx+bx SB=a-gx-bx Therefore, SA+SB=2a, and the tangential acceleration a is, This can be calculated as a = (SA + SB) / 2.

[0035] Prior to starting measurement, the operator instructs the control unit 204 of the arithmetic device 2 to execute calibration while the angular velocity of the rotating shaft 500 is constant, preferably while the rotating shaft 500 is stationary. The control unit 204, which has been instructed to perform calibration, instructs the gain / offset adjustment unit 101 to perform a calibration operation for adjusting the gain and offset, via the wireless communication unit 201 and the wireless interface 104 of the rotation detector 1. Upon receiving the instruction, the gain / offset adjustment unit 101 executes a calibration operation and sets the gain and offset adjustment values ​​to be applied to the first acceleration sensor 161 so that the sum signal of the output of the gain / offset adjustment unit 101 and the output of the second acceleration sensor 162 output by the addition unit 102 becomes zero.

[0036] Here, when the angular velocity of the rotating shaft 500 is constant or the rotating shaft 500 is stationary, the angular acceleration of the rotating shaft 500 is 0, and the tangential acceleration a applied to the first acceleration sensor 161 and the second acceleration sensor 162 is 0. If the gains and offsets of the first acceleration sensor 161 and the second acceleration sensor 162 are equal, the sum signal SA+SB obtained by adding the acceleration SA detected by the first acceleration sensor 161 and the acceleration SB detected by the second acceleration sensor 162 is expressed as follows: SA+SB=(gx+bx)+(-gx-bx)=0.

[0037] Also, when there is no acceleration b, SA+SB=(gx)+(-gx)=0. Therefore, by setting the gain and offset adjustment values ​​applied to first acceleration sensor 161 so that the added signal output by adder 102 becomes 0, the output of gain / offset adjustment unit 101 can be adjusted to the signal that first acceleration sensor 161 would output if the gain and offset of first acceleration sensor 161 were equal to those of second acceleration sensor 162.As a result, where the output of gain / offset adjustment unit 101 is SA and the output of second acceleration sensor 162 is SB, the above-mentioned SA+SB=2a, a=(SA+SB) / 2 holds.

[0038] Now, when gain / offset adjustment unit 101 has set the adjustment values ​​for gain and offset to be applied to the output of first acceleration sensor 161 so that the addition signal becomes 0, it completes the calibration operation, and thereafter adjusts the gain and offset of the output of first acceleration sensor 161 using the set adjustment values.

[0039] Furthermore, when the calibration operation is completed, the gain / offset adjustment unit 101 notifies the control unit 204 of the completion of calibration via the wireless interface 104 and the wireless communication unit 201 of the calculation device 2. Upon receiving the notification, the control unit 204 notifies the operator that measurement preparation is complete by display output, audio output, etc., and instructs the calculation processing unit 202 to start measurement.

[0040] Next, when measurement is started, the calculation processing unit 202 starts calculation processing of the sum signal SA+SB, which is obtained by adding the output of the gain / offset adjustment unit 101 and the output of the second acceleration sensor 162 by the addition unit 102 and is input to the calculation processing unit 202 via the analog-to-digital converter 103, the wireless interface 104, and the wireless communication unit 201, and outputs the calculation result as a digital measurement signal DO and an analog measurement signal AO.

[0041] The calculation process performed by the calculation processing unit 202 is as follows when the tangential acceleration a is to be measured: a=(SA+SB) / 2 The following calculation is performed. Here, tangential acceleration = radius × angular acceleration, and tangential acceleration is proportional to angular acceleration. Therefore, even if tangential acceleration a is the measurement subject, the behavior and characteristics of the angular acceleration of rotating shaft 500 can be evaluated from tangential acceleration a. However, the angular acceleration ω′ of the rotating shaft 500 may also be measured. In this case, the calculation processing unit 202 calculates a=(SA+SB) / 2, ω'=a / r Here, r is the distance (radius of rotation) from the set axis C, which is set in advance in the calculation processing unit 202, to the first acceleration sensor 161 and the second acceleration sensor 162.

[0042] Furthermore, the calculation processing unit 202 may further calculate other physical quantities related to the rotation of the rotating shaft 500, such as integrating the angular acceleration ω′ to calculate the angular velocity ω of the rotating shaft 500. As described above, in this embodiment, the tangential acceleration due to the angular acceleration of the rotating shaft 500 and the angular acceleration of the rotating shaft 500 are measured from the tangential acceleration detected by the first acceleration sensor 161 and the second acceleration sensor 162 provided on the rotation detector 1 which is fixed to the rotating shaft 500 as an after-market attachment.

[0043] Therefore, according to this embodiment, physical quantities correlated with angular acceleration, such as the tangential acceleration and angular acceleration of the rotating shaft 500, can be detected by a rotation measurement system that can be retrofitted to the rotating shaft 500 with high time resolution, even at low rotation speeds, compared to the case where angular acceleration is detected by differentiating the rotation speed detected by a rotation sensor.

[0044] In this embodiment, the first acceleration sensor 161 and the second acceleration sensor 162 are fixed at positions that are symmetrical with respect to a set axis C of the rigid, integrated main base 11. The rotation detector 1 has a structure in which the set axis C coincides with the central axis of rotation of the rotating shaft 500 by clamping the rotating shaft 500 by fastening the main base 11 and the sub-base 12 together.

[0045] Therefore, the first acceleration sensor 161 and the second acceleration sensor 162 can be fixed with high precision at positions that are linearly symmetrical about the central axis of rotation of the rotating shaft 500 for measurement, thereby achieving accurate measurement without any installation error. Furthermore, since the clamping block 15, which is the part that directly clamps the rotating shaft 500, is provided replaceable, the rotation detector 1 can be applied to rotating shafts 500 having different diameters. In the above embodiment, as shown in FIG. 4, the gain and offset of the output of the first acceleration sensor 161 are adjusted on the rotation detector 1 side, and the output of the first acceleration sensor 161 after the adjustment is added to the output of the second acceleration sensor 162. However, these adjustments and additions may be performed on the calculation device 2 side.

[0046] That is, in this case, as shown in FIG. 6, the signal processing system of the rotation detector 1 is composed of a first acceleration sensor 161, a second acceleration sensor 162, a first analog-to-digital converter 61, a second analog-to-digital converter 62, a first wireless interface 63, and a second wireless interface 64.

[0047] Then, the output of the first acceleration sensor 161 is converted into a digital signal by the first analog-digital converter 61 and wirelessly transmitted from the first wireless interface 63 to the calculation device 2, and the output of the second acceleration sensor 162 is converted into a digital signal by the second analog-digital converter 62 and wirelessly transmitted from the second wireless interface 64 to the calculation device 2.

[0048] Furthermore, the wireless communication unit 201 of the calculation device 2 is capable of receiving 2ch wireless signals, and the digital signals of the output of the first acceleration sensor 161 and the output of the second acceleration sensor 162 received in the calculation processing unit 202 via the wireless communication unit 201 are adjusted in gain and offset as described above, and the adjusted output of the first acceleration sensor 161 and the output of the second acceleration sensor 162 are added together as pre-processing of the above-mentioned calculation processing.

[0049] In the above embodiments, two-axis or three-axis acceleration sensors may be used as the first acceleration sensor 161 and the second acceleration sensor 162. As shown in FIG. 7a, the first acceleration sensor 161 detects not only a tangential acceleration SA of a circle centered on the set axis C and passing through the first acceleration sensor 161, but also a radial acceleration DA of the circle centered on the set axis C and passing through the first acceleration sensor 161. The second acceleration sensor 162 detects not only a tangential acceleration SB of a circle centered on the set axis C and passing through the second acceleration sensor 162, but also a radial acceleration DB of the circle centered on the set axis C and passing through the first acceleration sensor 161. The accelerations DA and DB may be used to correct the influence of deviation of the central axis of rotation of the rotating shaft 500 from the set axis C.

[0050] 7b, an XY coordinate system is set in a plane perpendicular to the axial direction of the rotating shaft 500, with the direction connecting the first acceleration sensor 161 and the second acceleration sensor 162 as the X direction, the direction perpendicular to the X direction as the Y direction, and the coordinate of the set axis C as the origin, and the rotation center axis C' of the rotating shaft 500 is shifted from the set axis C by dx in the X direction and dy in the Y direction, and the coordinate of the rotation center axis C' is (dx, dy). In addition, the distance from the set axis C to the first acceleration sensor 161 and the distance from the set axis C to the second acceleration sensor 162 are r, the distance from the rotation center axis C' to the first acceleration sensor 161 is rA, the distance from the rotation center axis C' to the second acceleration sensor 162 is rB, the inclination of the line connecting the rotation center axis C' and the first acceleration sensor 161 with respect to the X axis is θA, and the inclination of the line connecting the rotation center axis C' and the second acceleration sensor 162 with respect to the X axis is θB, then the following formulas 1 and 2 are established.

[0051] COSθA=(r-dx) / rA...Equation 1 COSθB=(r+dx) / rB...Equation 2 Furthermore, if the angular velocity of the rotating shaft 500 is ω, then the radial acceleration DA detected by the first acceleration sensor 161 is the X-direction component of the centrifugal acceleration rA·ω2 about the central axis of rotation C', and the radial acceleration DB detected by the second acceleration sensor 162 is the X-direction component of the centrifugal acceleration rB·ω2 about the central axis of rotation C', and the following equations 3 and 4 hold.

[0052] DA=rA·ω2·COSθA...Equation 3 DB=rB·ω2·COSθB...Eq.4 Substituting equations 1 and 2 into equations 3 and 4, DA=(rA·ω2)·{(r-dx) / rA}=ω2·(r-dx) DB=(rB·ω2)·{(r+dx) / rB}=ω2·(r+dx) Therefore, equation 5 holds.

[0053] DA / DB=ω2·(r-dx) / ω2·(r+dx)=(r-dx) / (r+dx)...Equation 5 Since r is a design value and DA / DB is calculated by dividing the detection value of the first acceleration sensor 161 by the detection value of the second acceleration sensor 162, As KD=DA / DB, dx={(1-KD)·r} / (1+KD)...Equation 6 and dx can be calculated by Equation 6. That is, dx can be calculated from the radial acceleration DA detected by the first acceleration sensor 161 and the radial acceleration DB detected by the second acceleration sensor 162.

[0054] Next, if the angular acceleration of rotating shaft 500 is ω', then tangential acceleration component aA due to the angular acceleration of rotating shaft 500 included in the tangential acceleration SA detected by first acceleration sensor 161 will be the Y-direction component of tangential acceleration rA · ω' about the central axis of rotation C', and tangential acceleration component aB due to the angular acceleration of rotating shaft 500 included in the tangential acceleration SB detected by second acceleration sensor 162 will be the Y-direction component of tangential acceleration rB · ω' about the central axis of rotation C', and their magnitudes are given by the following equations 7 and 8.

[0055] aA=rA·ω'·COSθA...Eq. 7 aB=rB·ω'·COSθB...Eq. 8 Here, from equations 1 and 2, aA=rA·ω'·COSθA=ω'·(r-dx)...Equation 9 aB=rB·ω'·COSθB=ω'·(r+dx)...Equation 10 Therefore, with a = r·ω', the first correction coefficient KA and the second correction coefficient KB are set by equations 9 and 10 using the calculated dx.

[0056] KA=a / aA=(r·ω') / (rA·ω'·COSθA)=r / (r-dx)...Equation 11 KB=a / aB=(r·ω') / (rB·ω'·COSθB)=r / (r+dx)...Equation 12 With KA and KB set in this way, KA·aA=a=r·ω'...Eq. 13 KB aB = a = r ω'...Eq. 14 It becomes.

[0057] Now, the detection axes of the acceleration components due to gravity and external forces of the tangential acceleration SA detected by the first acceleration sensor 161 and the tangential acceleration SB detected by the second acceleration sensor 162 are always in opposite directions in a fixed system. Therefore, SA+SB=(aA+gx+bx)+(aB-gx-bx)=aA+aB It becomes.

[0058] Here, as shown in Equations 9 and 10, aA=ω'·(r-dx) aB=ω'·(r+dx) Therefore, SA+SB=aA+aB=ω'·2r Thus, the effect of deviation of the rotation center axis C' from the set axis C is eliminated by SA+SB.

[0059] On the other hand, it is also possible to eliminate the influence of deviation of the rotation center axis C' from the set axis C by calculating the tangential acceleration a while also reflecting the information on DA and DB. That is, from equations 9 and 10, aA / aB = (r-dx) / (r+dx), and from equation 5, aA / aB = DA / DB. And, if DA / DB=aA / aB=KD, then SA+SB=aA+aB=aA+(1 / KD)·aA={(1 / KD)+1)}·aA Next aA= can be calculated as aA=(SA+SB) / {(1 / KD)+1)}.

[0060] Also, SA+SB=aA+aB=(KD·aB)+aB=(1+KD)aB, aB= can be calculated as aB=(SA+SB) / (1+KD). Then, using KA and KB in Equations 13 and 14, a=r·ω'=(KA·aA+KB·aB) / 2 The tangential acceleration a is detected by In addition, if the gravitational acceleration g can be ignored because the rotation axis is vertical or in a gravity-free space, and the acceleration b is not taken into account, a={(KA·SA)+(KB·SB)} / 2 or a=KA·SA and a = KB SB In this way, it is possible to eliminate the influence of deviation of the rotation center axis C' from the set axis C, which cannot be eliminated when only a single acceleration sensor is provided.

[0061] When the tangential acceleration a is calculated as a=KA·SA, the second acceleration sensor 162 does not need to detect the tangential acceleration SB, and when the tangential acceleration a is calculated as a=KB·SB, the first acceleration sensor 161 does not need to detect the tangential acceleration SA. Therefore, the rotation detector 1 is provided with a detection unit that calculates the tangential acceleration a as described above, and the detected tangential acceleration a is transmitted to the calculation device 2. Furthermore, the calculation processing unit 202 of the calculation device 2 may calculate other physical quantities related to the rotation of the rotating shaft 500, such as calculating the angular acceleration ω' using ω'=a / r, or calculating the angular velocity ω of the rotating shaft 500 by integrating the angular acceleration ω'.

[0062] However, such calculation and evaluation functions may be performed in an arbitrary functional division manner in cooperation between the rotation detector 1 and the calculation device 2. For example, SA and DA detected by the first acceleration sensor 161 and SB and DB detected by the second acceleration sensor 162 may be wirelessly transmitted to the calculation device 2, and the calculation processing unit 202 of the calculation device 2 may perform calculations of the tangential acceleration a, angular acceleration ω', etc. as described above.

[0063] In addition, the calculation device 2 may obtain the above-mentioned SA, SB, DA, DB, KD, dx, aA, aB, etc. from the rotation detector 1, and perform an analysis, etc., based on the obtained values ​​to evaluate the deviation of the rotation center axis C' from the set axis C. 8a1 and 8a2, the main base 11 and the sub-base 12 of the rotation detector 1 of the above embodiment may be connected using a screw 14 that vertically connects the left end of the sub-base 12 to the left end of the lower part of the main base 11 and a screw 14 that vertically connects the right end of the sub-base 12 to the right end of the lower part of the main base 11, without using a hinge 13. Also, other mechanisms or structures may be used as long as they can mechanically fasten the main base 11 and the sub-base 12.

[0064] In addition, in the above embodiment, the rotation detector 1 is fixed to the rotating shaft 500 using the clamping block 15, but this may be done using other mechanisms or structures as long as it can fix the rotation detector 1 to the rotating shaft 500 so that the set axis C coincides with the central axis of rotation of the rotating shaft 500.

[0065] For example, as shown in FIGS. 8b1, b2, and b3, the rotation detector 1 may be fixed to the rotating shaft 500 using three clamping screws 800 instead of the clamping block 15. As shown in the figures, the rotation detector 1 is fixed to the rotating shaft 500 as shown in Fig. 8b3 by opening the hinge 13 and inserting the rotating shaft 500 so as to cover the hollow portion 111 of the main base 11 as shown in Fig. 8b1, and then closing the hinge 13 and fastening the sub-base 12 to the main base 11 with the screw 14 as shown in Fig. 8b2.

[0066] As shown in Figure 8b3, when the sub-base 12 is fastened to the main base 11 with screws 14, two screw holes that penetrate from the outer periphery to the hollow portion 111 are provided on the main base 11 and one on the sub-base. These three screw holes can be used to attach three clamping screws 800 so that their tips protrude into the hollow portion 111.

[0067] The three screw holes are arranged so that the orientations of the three clamping screws 800 differ by 120 degrees around the set axis C when the main base 11 and sub-base 12 are fastened together with the screws 14, and the rotation detector 1 is fixed to the rotating shaft 500 by clamping the rotating shaft 500 from directions that differ by 120 degrees with the tips of the three clamping screws 800 with different orientations.

[0068] In addition, the length of each clamping screw 800 is set so that when the rotating shaft 500 is clamped with the three clamping screws 8000 that are completely screwed into the screw holes, the set axis C coincides with the central axis of rotation of the rotating shaft 500. Furthermore, by replacing the clamping screw 800 attached to the rotation detector 1 with a clamping screw 800 having a different length, the rotation detector 1 can be fixed to a rotating shaft 500 having a different diameter. In addition, by changing the amount of screwing of each clamping screw 800, adjustments such as making the set axis C coincide with the central axis of rotation of the rotating shaft 500 can also be performed. As shown in the left side view of FIG. 8c1 and the right side view of FIG. 8c2, the three clamping screws 800, the first acceleration sensor 161, and the second acceleration sensor 162 are aligned in the front-to-rear direction so as to prevent unnecessary moments from being generated. Furthermore, even when the rotating shaft 500 is clamped using the clamping screw 800 in this manner, the main base 11 and sub-base 12 of the rotation detector 1 may be connected using a screw 14 that vertically connects the left end of the sub-base 12 to the left end of the lower part of the main base 11, and a screw 14 that vertically connects the right end of the sub-base 12 to the right end of the lower part of the main base 11, without using a hinge 13, as shown in Fig. 8d. Also, other mechanisms and structures may be used as long as they can mechanically fasten the main base 11 and the sub-base 12.

[0069] Here, the rotation measurement system as described above is applicable to various rotating shafts 500. For example, as shown in FIG. 9a, if the left and right drive shafts 900 of an electric vehicle are fixed as rotating shafts 500 to a rotation detector 1, the angular velocities of the left and right drive shafts 900, tangential acceleration proportional to the angular velocities, angular acceleration, angular velocities, etc. can be measured. When applied to a transmission shaft that transmits torque, such as the drive shaft 900, it is also preferable that the above rotation detector 1 also has a function of measuring the torque of the rotating shaft 500. In this case, for example, as shown in Figure 9b1, a composite detector is formed having a structure in which a rotation detector 1 and a fixing device 910 that can be fixed to a rotating shaft 500 by a mechanism similar to that of the rotation detector 1 are connected in the axial direction of the rotating shaft 500 by a beam-shaped strain-flexible part 912 to which a strain gauge 911 is attached, and the strain generated in the strain-flexible part 912 in response to the torque transmitted by the rotating shaft 500 is detected by the strain gauge 911, and the detected strain is wirelessly transmitted to a calculation device 2, where the amount of strain is converted into torque.

[0070] Alternatively, as shown in FIG. 9b2, two rotation detectors 1 connected in the axial direction of a set axis C by a beam-shaped elastic body 921 are fixed to a rotating shaft 500, and the moment of inertia of the two rotation detectors 1 connected by the elastic body 921 and the rotating shaft 500 is I, the distance from the set axis C to the first acceleration sensor 161 or the second acceleration sensor 162 is r, and the difference between the tangential acceleration a measured using one rotation detector 1 and the tangential acceleration a measured using the other rotation detector 1 is Δa. Then, the torque T is calculated as follows: T=I×Δa / r It may also be calculated by:

[0071] However, the two rotation detectors 1 do not necessarily need to be connected by the elastic body 921. The two rotation detectors 1 may be fixed at positions spaced a predetermined distance apart in the axial direction of the rotating shaft 500, and the above formula may be satisfied. T=I×Δa / r The torque T may be calculated by the following. [Explanation of symbols]

[0072] 1...rotation detector, 2...calculation device, 11...main base, 12...sub-base, 13...hinge, 14...screw, 15...clamping block, 61...first analog-digital converter, 62...second analog-digital converter, 63...first wireless interface, 64...second wireless interface, 101...gain / offset adjustment unit, 102...addition unit, 103...analog-digital converter, 104...wireless interface, 111...hollow portion, 112...first mounting groove, 121...second mounting groove, 161...first acceleration sensor, 162...second acceleration sensor, 201...wireless communication unit, 202...calculation processing unit, 203...digital-analog converter, 204...control unit, 500...rotating shaft, 800...clamping screw, 900...drive shaft, 910...fixing device, 911...strain gauge, 912...strain-generating portion, 921...elastic body.

Claims

1. A rotation measurement device for measuring the rotation of a rotating shaft, comprising: The main base and A sub-base that can be fastened to the main base; A first acceleration sensor fixed to the main base; a second acceleration sensor fixed to the main base, the main base and the sub-base are fastened to each other so as to sandwich the rotating shaft in a radial direction of the rotating shaft, so that a setting axis by which a relative position of the main base is fixedly determined coincides with a rotation central axis of the rotating shaft, the first acceleration sensor and the second acceleration sensor are disposed at positions that are linearly symmetrical with respect to the setting axis of the main base, a rotation measuring device characterized in that the first acceleration sensor detects an acceleration in a direction of a tangent to a circle centered on the set axis and passing through the first acceleration sensor as a first tangential acceleration, and the second acceleration sensor detects an acceleration in a direction of a tangent to the circle passing through the second acceleration sensor as a second tangential acceleration.

2. The rotation measurement device according to claim 1, the main base has a rotating shaft accommodating space that is a space including the set axis therein and is formed by a recess in a direction perpendicular to the set axis, and has a shape that includes positions that are linearly symmetrical with respect to the set axis, where the first acceleration sensor and the second acceleration sensor are disposed, on both sides of the recess; A rotation measuring device characterized in that the sub-base is fastened to the main base so as to cover an opening of the rotating shaft accommodating space with the rotating shaft accommodated in the rotating shaft accommodating space of the main base.

3. The rotation measurement device according to claim 1, the main base has one or more first clamping members attached to the main base and having an end that abuts against an outer circumferential surface of the rotating shaft when the main base and the sub-base are fastened to each other; the sub-base has one or more second clamping members attached to the sub-base and having an end that abuts against an outer circumferential surface of the rotating shaft when the main base and the sub-base are fastened to each other; the main base and the sub-base clamp the rotating shaft in a radial direction of the rotating shaft by an end of the first clamping member abutting against an outer circumferential surface of the rotating shaft and an end of the second clamping member abutting against an outer circumferential surface of the rotating shaft, the first clamping member is replaceably attached to the main base, and a distance from an end of the first clamping member to the setting axis can be changed by replacing the first clamping member; The second clamping member is attached to the sub-base in a replaceable manner, and by replacing the second clamping member, the distance from the end of the second clamping member to the setting axis when the main base and the sub-base are fastened can be changed.

4. The rotation measurement device according to claim 3, the main base has a rotating shaft accommodating space that is a space including the set axis therein and is formed by a recess in a direction perpendicular to the set axis, and has a shape that includes positions that are linearly symmetrical with respect to the set axis, where the first acceleration sensor and the second acceleration sensor are disposed, on both sides of the recess; the sub-base is fastened to the main base so as to cover an opening of the rotating shaft accommodating space in a state in which the rotating shaft is accommodated in the rotating shaft accommodating space of the main base, A rotation measuring device characterized in that the first clamping member is attached so that an end thereof protrudes from the surface of the main base facing the rotating shaft accommodating space, and the second clamping member is attached so that an end thereof protrudes from the surface of the main base that faces the rotating shaft accommodating space when the main base and the sub-base are fastened together.

5. 5. The rotation measurement device according to claim 1, 2, 3 or 4, A rotation detection means is provided. the second acceleration sensor detects, as the second tangential acceleration, an acceleration in a direction of a tangent to the circle passing through the second acceleration sensor, the same circumferential direction as the first tangential acceleration, and the positive and negative signs of the acceleration are the same; The rotation measuring device according to claim 1, wherein the rotation detection means calculates an acceleration obtained by adding the first tangential acceleration and the second tangential acceleration as a detected tangential acceleration.

6. The rotation measurement device according to claim 5, A rotation measuring device characterized in that the rotation detection means calculates the angular acceleration of the rotating shaft by dividing the detected tangential acceleration by a radius of the circle.

7. 5. The rotation measurement device according to claim 1, 2, 3 or 4, An adjustment means; An adjustment amount setting means; A rotation detection means is provided. the second acceleration sensor detects, as the second tangential acceleration, an acceleration in a direction of a tangent to the circle passing through the second acceleration sensor, the same circumferential direction as the first tangential acceleration, and the positive and negative signs of the acceleration are the same; the adjusting means adjusts at least one of the first tangential direction acceleration and the second tangential direction acceleration with a set gain and offset, and outputs the adjusted acceleration; the adjustment amount setting means sets the gain and the offset so that a sum of the first tangential direction acceleration and the second tangential direction acceleration outputted from the adjustment means becomes 0 when the angular acceleration of the rotating shaft is 0; A rotation measuring device characterized in that the rotation detection means calculates, as a detected tangential acceleration, an acceleration obtained by adding together the first tangential acceleration and the second tangential acceleration output from the adjustment means.

8. The rotation measurement device according to claim 7, A rotation measuring device characterized in that the rotation detection means calculates the angular acceleration of the rotating shaft by dividing the detected tangential acceleration by a radius of the circle.

9. A rotation measurement device for measuring the rotation of a rotating shaft, comprising: a base removably fixed to the rotating shaft so as to rotate together with the rotating shaft; A first acceleration sensor fixed to the base; A second acceleration sensor fixed to the base; A rotation detection means is provided. the base is fixed to the rotating shaft such that a setting axis, the relative position of which with respect to the base is fixed, coincides with a rotation central axis of the rotating shaft; the first acceleration sensor and the second acceleration sensor are disposed at positions that are linearly symmetric with respect to the set axis, the first acceleration sensor detects an acceleration in a direction of a tangent to a circle centered on the set axis and passing through the first acceleration sensor as a first tangential acceleration, and detects an acceleration in a radial direction of the circle passing through the first acceleration sensor as a first radial acceleration; the second acceleration sensor detects, as a second radial acceleration, an acceleration in a radial direction of the circle passing through the second acceleration sensor and toward a center of the circle, the acceleration having the same positive and negative values ​​as the first radial acceleration, The rotation detection means is a ratio of the first radial acceleration to the second radial acceleration, the ratio being in a range from 0 to 10 ...

10. The rotation measurement device according to claim 9, the second acceleration sensor detects, as a second tangential acceleration, an acceleration in a direction of a tangent to the circle passing through the second acceleration sensor, the same circumferential direction as the first tangential acceleration, and the positive and negative signs of the acceleration are the same; The rotation detection means calculates a tangential acceleration a due to the angular acceleration of the rotating shaft by: SA, SB, DA, DB, a radius of the circle, a tangential acceleration component aA due to the angular acceleration of the rotating shaft in the first tangential acceleration SA, and a tangential acceleration component aB due to the angular acceleration of the rotating shaft in the second tangential acceleration SB, KD=DA / DB, dx = {(1-KD) x r} / (1+KD) KA=r / (r-dx) KB=r / (r+dx) As, aA = (SA + SB) / {(1 / KD) + 1)} aB=(SA+SB) / (1+KD) a = {(KA・aA) + (KB・aB)} / 2 or, a = {(KA・SA) + (KB・SB)} / 2 A rotation measuring device characterized by calculating the rotational speed by the following formula.

11. The rotation measurement device according to claim 10, A rotation measuring device characterized in that the rotation detection means calculates the angular acceleration of the rotating shaft by dividing the tangential acceleration a by the radius of the circle.

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