JP6782602B2 - Fluid measurement tachometer - Google Patents

Description

The present invention relates to a fluid measurement tachometer that obtains the flow rate and flow velocity of the fluid to be measured from the rotation information of the impeller.

Conventionally, as a method of measuring rotation information of a rotating body in a non-contact manner, a measurement method by reflection of light has been generally used (see, for example, Patent Document 1). In this measurement method based on light reflection, for example, when measuring the rotation speed of a rotating body in a non-contact manner, a reflecting plate is attached to the side surface of the rotating body to irradiate the rotating body with light, and the period of intensity of the reflected light from the reflecting plate. To measure.

As an example, FIG. 20 shows an example in which the flow velocity of a fluid (fluid to be measured) flowing through a flow path is measured by reflection of light. In the figure, 1 is a casing, 2 is an impeller (rotating body), and 3 is a light emitting / receiving device. The casing 1 includes an introduction port 1a for introducing the fluid to be measured, a discharge port 1b for discharging the fluid to be measured introduced from the introduction port 1a, and a flow path 1c for communicating the introduction port 1a and the discharge port 1b. ing.

The impeller 2 is provided in the flow path 1c and rotates about the axis J of the rotation shaft in response to the flow of the fluid to be measured flowing in the flow path 1c. A reflector 4 is attached to the side surface of the blade 2a of the impeller 2. The casing 1 is provided with a transparent window 5 for looking into the reflector 4 attached to the impeller 2.

The light emitting / receiving device 3 shines light on the impeller 2 in the casing 1 through the window 5, receives the reflected light from the reflector 4, and outputs a signal according to the intensity of the received reflected light (see FIG. 21). ). The rotation speed of the impeller 2 is obtained from the period of the signal output by the light emitter / receiver 3, and the flow velocity of the fluid to be measured flowing through the flow path 1c is measured from the rotation speed of the impeller 2.

However, in this measurement method based on the reflection of light, the rotation speed and the number of rotations can be detected as the rotation information of the rotating body, but the rotation direction and the rotation angle of the rotating body cannot be easily detected. Further, in principle, the reflector cannot be placed on the rotation axis, and there are restrictions on miniaturization. Further, when the rotating body is completely housed in the casing and cannot be accessed from the outside, for example, when the casing internal pressure is high in the turbine and a window cannot be provided, it is impossible to detect the rotation information of the rotating body. ..

On the other hand, as another method of measuring the rotation information of the rotating body in a non-contact manner, there is a method using a magnetoresistive element (MR element). When the direction of the magnetic field parallel to the surface on which the magnetoresistive element is arranged changes, the resistance value of the magnetoresistive element changes accordingly. The direction of the magnetic field can be detected from the change in the resistance value of the magnetoresistive element, and the relative rotation angle between various members can be detected from the direction of the magnetic field.

FIG. 22 shows the main part of the circuit configuration of the angle sensor (magnetic sensor) using the magnetoresistive element. In the figure, reference numeral 6 denotes a magnetic sensor, which is composed of bridge-connected magnetoresistive elements 6a to 6d. The magnetoresistive elements 6a to 6d are formed on the substrate surface as an electrode pattern. The magnetic sensor 6 is driven by a constant current I, and uses a potential difference V (θ) between the connection point between the magnetoresistive elements 6a and 6b and the connection point between the magnetoresistive elements 6c and 6d as a detection output. In this example, the magnetic sensor 6 is driven by a constant current, but a method of driving by a constant voltage may be adopted.

In the magnetic sensor 6, a magnetic field parallel to the electrode patterns of the magnetoresistive elements 6a to 6d formed on the substrate surface is defined as B, and the magnetic field B is assumed to rotate. θ is the angle of rotation of the magnetic field B. In this case, the resistance values of the magnetoresistive elements 6a to 6d change, and the detection output V (θ) changes. The direction of the magnetic field B can be detected from the change in the detection output V (θ).

That is, as shown in FIG. 23, assuming that the magnetic field B rotates with the rotation of the rotating body 7, the rotation angle of the rotating body 7 can be detected from the direction of the magnetic field B. In FIG. 23, 7-1 is a rotating shaft of the rotating body 7, 8-1 and 8-2 are a pair of magnets (magnetic field generators) provided on the rotating body 7, and the magnetic sensor 6 is this magnet. It is fixedly installed in the magnetic field B generated by 8-1 and 8-2. In this example, it is fixed to the member 9.

In this magnetic sensor 6, the resistance values of the magnetoresistive elements 6a and 6c are R (θ), the resistance values of the magnetoresistive elements 6b and 6d are R (θ-90 °), and the magnitude of the magnetoresistive effect is ΔR (ΔR =). R _H- R _V )
R (θ) = R _H · cos ² θ + R _V · sin ² θ ・ ・ ・ ・ (1)
R (θ-90 °) = R _H・ sin ² θ + R _V・ cos ² θ ・ ・ ・ ・ (2)
Represented as
The detection output V (θ) is
V (θ) = (I / 2) ・ ΔR ・ cos (2θ) ・ ・ ・ ・ (3)
It is expressed as.
However, R _V : the resistance value when a magnetic field is applied vertically to the magnetoresistive element (minimum value), and R _H : the resistance value when a magnetic field is applied horizontally to the magnetoresistive element (maximum value).

FIG. 24 shows an example in which the magnetic sensor 6 is used in the flow meter in which the rotating body is the impeller 2. In this example, a pair of magnets 8-1 and 8-2 are embedded in the blades 2a and 2b of the impeller 2, and the magnets 8-1 and 8-2 generate a magnetic field B (orthogonal to the rotation axis of the impeller 6). The magnetic sensor 6 is fixedly installed so that the center thereof coincides with the axis J of the rotation axis of the impeller 6 (in the plane). FIG. 25 shows a partially broken sectional view seen from the direction A in FIG. 24.

In FIG. 24, when the impeller 2 rotates, the detection output V (θ) of the magnetic sensor 6 increases or decreases, and one half rotation becomes one cycle (see FIG. 26). When the impeller 2 is rotating in one direction, it can be counted as one rotation when it reaches the peak twice from the time when the detection output V (θ) reaches the peak value (Vp = (I / 2) · ΔR). .. However, since the detection output V (θ) has inversion symmetry, the rotation direction cannot be detected. Further, when the detection output V (θ) rotates beyond the monotonically increasing range, the angle is not uniquely determined, and the angle sensor using the magnetoresistive element has a monotonically increasing range of only π / 2.

On the other hand, as shown in FIG. 27 as a reference example, the two magnetic sensors 6-1 and 6-2 are provided with a rotational misalignment δ in the magnetic field B generated by the magnets 8-1 and 8-2. It is conceivable to install it fixedly. FIG. 28 shows a partially broken cross-sectional view seen from the direction of arrow A in FIG. 27. In FIG. 27, when the impeller 2 rotates, the detection output V1 (θ) of the magnetic sensor 6-1 and the detection output V2 (θ) of the magnetic sensor 6-2 increase or decrease (see FIG. 29).

In this case, since the magnetic sensors 6-1 and 6-2 are installed with a rotational position deviation δ, the detection output V1 (θ) of the magnetic sensor 6-1 and the detection output V2 of the magnetic sensor 6-2 A phase difference occurs between the magnetometer and (θ), the magnetic sensor 6-1 outputs a detection output of V1 (θ) = Vp · cos (2θ), and the magnetic sensor 6-2 outputs V2 (θ) = Vp · cos (2θ). The detection output of (2 (θ-δ)) is output.

With such a configuration, it is possible to detect the rotation direction of the impeller 2 from the detection output V1 (θ) of the magnetic sensor 6-1 and the detection output V2 (θ) of the magnetic sensor 6-2. For example, at the position of P1 in FIG. 29, V1 (θ)> V2 (θ), so when the value of V1 (θ) rises (dV1 / dt> 0), the value of V1 (θ) falls in the forward direction. In the case of (dV1 / dt <0), it can be determined that the direction is opposite. Further, at the position of P2 in FIG. 29, V1 (θ) <V2 (θ), so when the value of V1 (θ) decreases (dV1 / dt <0), the value of V1 (θ) increases in the forward direction. When (dV1 / dt> 0), it can be determined that the direction is opposite.

JP-A-2002-5701

However, from the detection outputs V1 (θ) and V2 (θ) as shown in FIG. 29, the rotation direction cannot be detected over the entire circumference of the rotating body. That is, at the position of P3 in FIG. 29, V1 (θ)> V2 (θ), but V1 (θ) is descending in the forward direction, and when “V1 (θ)> V2 (θ), When the value of V1 (θ) rises, the determination condition of "forward direction" is not satisfied. The section in which this judgment condition is not satisfied is called a non-satisfaction section, and the section in which the judgment condition is satisfied is called a valid section. In FIG. 29, the unsuccessful section is indicated by a diagonal line. When such an unsuccessful section occurs, the measurement accuracy of the fluid measurement tachometer that obtains the flow rate and flow velocity of the fluid to be measured from the rotation information of the impeller is impaired.

The present invention has been made to solve such a problem, and an object of the present invention is to enable detection of a rotation direction over the entire circumference of an impeller, such as a flow rate and a flow velocity of a fluid to be measured. An object of the present invention is to provide a fluid measurement tachometer capable of improving measurement accuracy.

In order to achieve such an object, the present invention presents the introduction port (21a) for introducing the measured fluid, the discharge port (21b) for discharging the measured fluid introduced from the introduction port, and the introduction port and the discharge port. An impeller (27) that is provided with a flow path (21c) that communicates with the magnetometer and rotates about a rotation axis in response to the flow of the fluid to be measured flowing in the flow path, and its direction changes as the impeller rotates. A casing (21) containing a magnetic field generator (12-1, 12-2) that generates a changing magnetic field, and a fixed magnetometer installed in the magnetic field outside the casing generated by the magnetic field generator, for rotation of the impeller. The first magnetic sensor (13-1) whose detection output changes in conjunction with the accompanying change in the direction of the magnetic field and the first magnetic sensor rotate in the magnetic field outside the casing generated by the magnetic field generator. The second magnetic sensor (13-2), which is fixedly installed with a misalignment δ and whose detection output changes in conjunction with the change in the direction of the magnetic field due to the rotation of the impeller, and the first magnetic sensor. The detection output is the first detection output, the detection output of the second magnetic sensor is the second detection output, and at least the rotation direction of the impeller is set to the rotation direction of the impeller based on the first detection output and the second detection output. A rotation information detection unit (30) that detects as rotation information and a fluid measurement unit (31) that obtains a desired measurement result regarding the fluid to be measured based on the rotation information of the impeller detected by the rotation information detection unit are calculated. A housing (22) built in as a part (29) is provided, and the first magnetic sensor has a first magnetic sensor when the rotation angle of the magnetic field accompanying the rotation of the impeller is θ and the maximum value of the first detection output is V1p. A voltage of V1 (θ) = V1p · cos (2θ) is generated as the detection output of 1, the second magnetic sensor sets the rotation angle of the magnetic field accompanying the rotation of the impeller by θ, and the maximum value of the second detection output. When is V2p, a voltage of V2 (θ) = V2p · cos (2 (θ−δ)) is generated as the second detection output, and the first detection output V1 (θ) generated by the first magnetic sensor. ) And the second detection output V2 (θ) generated by the second magnetic sensor, the maximum value V2p of the second detection output V2 (θ) is from the maximum value V1p of the first detection output V1 (θ). It is also large and is characterized by intersecting at a point where V1 (θ) = V1p.

In the present invention, the second magnetic sensor is fixedly installed in the magnetic field generated by the magnetic field generating unit with a rotational position shift δ with respect to the first magnetic sensor. The first magnetic sensor generates a voltage of V1 (θ) = V1p · cos (2θ) as the first detection output in conjunction with the change in the direction of the magnetic field accompanying the rotation of the impeller, and the second magnetism. The sensor generates a voltage of V2 (θ) = V2p · cos (2 (θ−δ)) as the second detection output in conjunction with the change in the direction of the magnetic field accompanying the rotation of the impeller. In this case, the maximum value of the first detection output V1 (θ) is V1p, and the maximum value of the second detection output V2 (θ) is V2p. In the present invention, the first detection output V1 (θ) generated by the first magnetic sensor and the second detection output V2 (θ) generated by the second magnetic sensor are the second detection output V2 (θ). ) Is larger than the maximum value V1p of the first detection output V1 (θ) (V2p> V1p), and intersects at the point of V1 (θ) = V1p.

As a result, in the present invention, there is no section (non-established section) in which the determination condition such as "V1 (θ)> V2 (θ), but V1 (θ) decreases in the forward direction" is not satisfied. It becomes possible to detect the rotation direction over the entire circumference of the impeller, and it becomes possible to improve the measurement accuracy of the flow rate and the flow velocity of the fluid to be measured.

In the present invention, since it is possible to detect the rotation direction over the entire circumference of the impeller, the impeller is the difference between the number of times the impeller has rotated in the forward direction and the number of times it has rotated in the opposite direction from the rotation reference position. It becomes possible to count the number of rotations of. Further, it is also possible to obtain the rotation angle from the rotation reference position of the impeller based on the detected rotation direction of the impeller, the number of rotations of the impeller counted, and the first detection output.

In the above description, as an example, the components on the drawing corresponding to the components of the invention are indicated by reference numerals in parentheses.

As described above, according to the present invention, the first detection output V1 (θ) generated by the first magnetic sensor and the second detection output V2 (θ) generated by the second magnetic sensor are combined with each other. The maximum value V2p of the second detection output V2 (θ) is made larger than the maximum value V1p of the first detection output V1 (θ), and the blades are crossed at the point of V1 (θ) = V1p. It becomes possible to detect the rotation direction over the entire circumference of the vehicle, and it becomes possible to improve the measurement accuracy of the flow rate and flow velocity of the fluid to be measured.

FIG. 1 is a plan view showing an example of a rotation detection sensor used in the fluid measurement tachometer according to the present invention. FIG. 2 is a perspective view of the rotation detection sensor. FIG. 3 is a waveform diagram showing the detection outputs V1 (θ) and V2 (θ) of the two magnetic sensors of the rotation detection sensor. FIG. 4 is a configuration diagram showing an outline of a rotation information detection unit attached to the rotation detection sensor. FIG. 5 is a diagram showing an example in which two magnetic sensors are installed separately on the upper side and the lower side of the rotating body. FIG. 6 is a diagram showing an installation example (Example 1) of two magnetic sensors when the two rotation axes are interlocked with each other. FIG. 7 is a diagram showing an installation example (Example 2) of two magnetic sensors when the two rotation axes are interlocked with each other. FIG. 8 is a diagram showing an installation example (Example 3) of two magnetic sensors when the two rotation axes are interlocked with each other. FIG. 9 is a diagram showing an example in which two magnetic sensors are installed at positions across the axis of the rotating shaft. FIG. 10 is a cross-sectional view taken from the direction C in FIG. FIG. 11 is a diagram showing an embodiment of a fluid measurement tachometer according to the present invention. FIG. 12 is a cross-sectional view taken along the line II in FIG. FIG. 13 is a waveform diagram showing the detection outputs V1 (θ) and V2 (θ) of the two magnetic sensors in this fluid measurement tachometer. FIG. 14 is a configuration diagram showing an outline of a calculation unit attached to the fluid measurement tachometer. FIG. 15 is a diagram showing a rotation direction determination condition used by the rotation direction determination unit in the calculation unit and a rotation speed count condition used by the rotation speed counting unit. FIG. 16 is a diagram showing an example of changes in the detection outputs V1 (θ) and V2 (θ) of the two magnetic sensors and an example of changes in the counted number of rotations N with the rotation of the impeller in this fluid measurement tachometer. .. FIG. 17 shows changes in the sign (positive / negative) of the slope “dV1 / dt” of the tangent line of the detection output V1 (θ) and the sign (positive / negative) of “V1 (θ) −V2 (θ)” due to the rotation of the impeller. It is a figure which illustrates the change. FIG. 18 is a diagram showing the calculated rotation angle θ'of the impeller in comparison with the actual rotation angle θ. FIG. 19 is a diagram showing an example in which two magnetic sensors are installed facing each other with the casing interposed therebetween. FIG. 20 is a diagram showing an example of measuring the flow velocity of the fluid to be measured by the reflection of light. FIG. 21 is a diagram showing signals according to the intensity of the received reflected light. FIG. 22 is a diagram showing a main part of a circuit configuration of an angle sensor (magnetic sensor) using a magnetoresistive element. FIG. 23 is a diagram showing an example using a magnetic sensor. FIG. 24 is a diagram showing an example in which a magnetic sensor is used in a flow meter using a rotating body as an impeller. FIG. 25 is a partially cutaway sectional view taken from the direction A in FIG. 24. FIG. 26 is a waveform diagram showing the detection output V (θ) of one magnetic sensor. FIG. 27 is a diagram showing an example (reference example) in which two magnetic sensors are fixedly installed with a rotational position shift δ. FIG. 28 is a partially cutaway sectional view taken from the direction of arrow A in FIG. 27. FIG. 29 is a waveform diagram showing the detection outputs V1 (θ) and V2 (θ) of the two magnetic sensors in the reference example.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

[Rotation detection sensor]
FIG. 1 is a plan view showing an example of a rotation detection sensor used in the fluid measurement tachometer according to the present invention. In the figure, 11 is a rotating body, 12-1 and 12-2 are a pair of magnets embedded in the rotating body 11, and 13-1 and 13-2 are magnetic sensors. As for the configuration of the magnetic sensors 13-1 and 13-2, FIG. 1 is a plan view showing a main part of the rotation detection sensor 100 according to the first embodiment of the present invention. In the figure, 11 is a rotating body, 12-1 and 12-2 are a pair of magnets embedded in the rotating body 11, and 13-1 and 13-2 are magnetic sensors. Since the configurations of the magnetic sensors 13-1 and 13-2 are the same as those of the magnetic sensor 6 described with reference to FIG. 22, the description thereof will be omitted.

In the rotation detection sensor 100, the magnetic sensors 13-1 and 13-2 are displaced in the magnetic field B generated by the magnets 12-1 and 12-2 (in a plane orthogonal to the rotation axis of the rotating body 11). It is fixedly installed with δ (δ ≠ nπ / 4 (n is an integer)). In this example, as shown in FIG. 2, the centers of the magnetic sensors 13-1 and 13-2 are aligned with the axis J of the rotation axis of the rotating body 11, and the magnetic sensor 13-1 and the magnetic sensor 13-2 are aligned with each other. And are installed on the upper side of the rotating body 11 so as to be vertically overlapped with each other at intervals.

In the rotation detection sensor 100, when the rotating body 11 rotates, the detection output V1 (θ) of the magnetic sensor 13-1 and the detection output V2 (θ) of the magnetic sensor 13-2 increase or decrease (see FIG. 3). In this case, since the magnetic sensors 13-1 and 13-2 are installed with a rotational position deviation δ, the detection output V1 (θ) of the magnetic sensor 13-1 and the detection output V2 of the magnetic sensor 13-2 A phase difference occurs with (θ), the magnetic sensor 13-1 outputs a detection output of V1 (θ) = V1p · cos (2θ), and the magnetic sensor 13-2 outputs V2 (θ) = V2p · cos. The detection output of (2 (θ-δ)) is output.

Here, in the example shown in FIG. 29, V1p = V2p = Vp, but in this rotation detection sensor 100, V2p> V1p, and the detection output V1 (θ) generated by the magnetic sensor 13-1 and the magnetic sensor 13- The detection output V2 (θ) generated by 2 is made to intersect at the point of V1 (θ) = V1p. Specifically, when θ = 0 °, V1 (θ) = V1p is set, and the detection output V1 (θ) generated by the magnetic sensor 13-1 and the detection generated by the magnetic sensor 13-2 at this point. Make sure that the output V2 (θ) intersects.

In this case, when θ = 0 °, the detection output V2 (θ) generated by the magnetic sensor 13-2 is V2 (θ) = V2p · cos (2 (θ−δ)) = V2p · cos (2δ). Become. Since this V2p · cos (2δ) is set to V1p, that is, V2p · cos (2δ) = V1p, the maximum value V2p of the detection output V2 (θ) is set to V2p = V1p / cos. (2δ) should be set. V1p and V2p can be set by adjusting the current and voltage applied to the magnetic sensors 13-1 and 13-2 (adjusting the output gain), or by creating a sensor resistance value.

With such a configuration, the rotation direction is detected over the entire circumference of the rotating body 11 from the detection output V1 (θ) of the magnetic sensor 13-1 and the detection output V2 (θ) of the magnetic sensor 13-2. Will be able to.

That is, when the rotating body 11 rotates in the forward direction, when the value of V1 (θ) rises (dV1 / dt> 0), V1 (θ)> V2 (θ) always, and the value of V1 (θ) becomes. When descending (dV1 / dt <0), V1 (θ) <V2 (θ) is always satisfied. Further, when the rotating body 11 rotates in the opposite direction, when the value of V1 (θ) rises (dV1 / dt> 0), V1 (θ) <V2 (θ) always, and the value of V1 (θ) becomes. When descending (dV1 / dt <0), V1 (θ)> V2 (θ) is always satisfied. As a result, the unsatisfied section of the determination condition as shown in FIG. 29 does not occur.

At the position of dV1 / dt = 0 (position of V1 (θ) = ± V1p), the rotation direction can be determined by looking at the value of V1 (θ) and the sign of dV2 / dt. That is, in the case of V1 (θ) = + V1p (P4 point), if dV2 / dt> 0 (rise), it can be determined to be in the forward direction, and if dV2 / dt <0 (down), it can be determined to be in the reverse direction. can do. Further, in the case of V1 (θ) = −V1p (P5 point), if dV2 / dt <0 (downward), it can be determined to be in the forward direction, and if dV2 / dt> 0 (increase), it is in the reverse direction. Can be determined.

FIG. 4 shows an outline of the rotation information detection unit 14 attached to the rotation detection sensor 100. The rotation information detection unit 14 has a first differential circuit 14-1 that detects the increasing / decreasing tendency of the detection output V1 (θ) of the magnetic sensor 13-1 as positive / negative of dV1 / dt (slope of the tangent line), and the magnetic sensor 13. The second differential circuit 14-2 that detects the increasing / decreasing tendency of the detection output V2 (θ) of -2 as the positive / negative of dV2 / dt (slope of the tangent line), the detection output V1 (θ) of the magnetic sensor 13-1, and the magnetism. Comparison circuit 14-3 that compares the magnitude of the detection output V2 (θ) of sensor 13-2, detection results in differential circuits 14-1 and 14-2, comparison results in comparison circuit 14-3, and magnetic sensor 13 The rotation direction determination unit 14-4 that determines the rotation direction of the rotating body 11 based on the detection output V1 (θ) of -1, the rotation direction determination result by the rotation direction determination unit 14-4, and the magnetic sensor 13- The number of rotations is counted as the difference between the number of times the rotating body 11 is rotated in the forward direction and the number of times the rotating body 11 is rotated in the opposite direction from the rotation reference position based on the detection output V1 (θ) of 1. The rotation of the rotating body 11 from the rotation reference position based on the number of rotations of the rotating body 11 counted by the unit 14-5 and the rotation number counting unit 14-5 and the detection output V1 (θ) of the magnetic sensor 13-1. It is provided with a rotation angle calculation unit 14-6 for obtaining an angle.

In the rotation information detection unit 14, the rotation direction determination unit 14-4 determines the rotation direction of the rotating body 11 according to the above-mentioned determination conditions. The determination of the rotation direction at the position of dV1 / dt = 0 (the position of V1 (θ) = ± V1p) is omitted because the rotating body 11 rarely stays at the position of dV1 / dt = 0. It may be a thing. The details of the rotation direction determination unit 14-4, the rotation speed counting unit 14-5, and the rotation angle calculation unit 14-6 will be specifically described in the embodiment described later.

In the rotation detection sensor 100, the magnetic sensors 13-1 and 13-2 are installed so as to overlap the upper side of the rotating body 11, but as shown in FIG. 5, the magnetic sensors 13-1 and 13- 2 may be installed separately on the upper side and the lower side of the rotating body 11.

Further, when two rotating shafts are interlocked like a gear, one magnetic sensor may be installed on each rotating shaft. For example, as shown in FIG. 6, when the left and right rotating shafts (gears) 16 and 17 rotate in conjunction with the central rotating shaft (gear) 15, a magnetic sensor 13-1 is installed on the rotating shaft 16 side. The magnetic sensor 13-2 is installed on the rotating shaft 17 side. In this case, a pair of magnets 12-1 and 12-2 are provided on the rotating shaft 16 side, a pair of magnets 12-3 and 12-4 are provided on the rotating shaft 17 side, and the rotating shafts 16 and 17 are rotated. The directions of the rotating magnetic fields B1 and B2 are detected by the magnetic sensors 13-1 and 13-2.

In FIG. 6, the directions of the magnetic fields B1 and B2 are parallel, but the directions of the magnetic fields B1 and B2 do not have to be parallel as long as the periods are the same. For example, as shown in FIG. 7, the directions of the magnetic fields B1 and B2 may be shifted by δ instead of shifting the rotation positions of the magnetic sensors 13-1 and 13-2. Further, in FIG. 6, the magnetically sensitive surfaces of the magnetic sensors 13-1 and 13-2 are arranged so as to face the same direction, but as shown in FIG. 8, the rotating shaft 16 and the rotating shaft 17 are used as staggered axes. , The magnetic sensing surfaces of the magnetic sensors 13-1 and 13-2 may be arranged so as to face in the orthogonal direction. In this case, the rotation positions of the magnetic sensors 13-1 and 13-2 may be shifted by δ, and the directions of the magnetic fields B1 and B2 may be shifted by δ. Further, the rotating shaft 16 and the rotating shaft 17 may be used as an intersecting shaft or the like.

In the present invention, assuming that the magnetic fields generated by the magnetic field generator are B1 and B2, when the directions of the magnetic fields B1 and B2 are shifted by δ, the magnetic sensor 13-2 is placed in the magnetic field B2 generated by the magnetic field generator. It can be said that the magnetic sensor 13-1 is fixedly installed with a rotational position shift δ (with respect to the magnetic field B1 detected by the magnetic sensor 13-1). That is, the present invention also includes the configurations shown in FIGS. 7 and 8 in the scope of rights.

Further, if a magnetic field is applied to the two magnetic sensors in the same direction, the two magnetic sensors do not have to be coaxial with the rotation axis. For example, as shown in FIG. 9, when the magnetic field B is applied to a wide range of the rotating body 18 in the same direction, it is not coaxial with the rotating shaft 18-1 of the rotating body 1, but is arbitrary in the magnetic field B. Magnetic sensors 13-1 and 13-2 may be installed at the positions. FIG. 10 shows a cross-sectional view of FIG. 9 as viewed from the C direction.

[Embodiment]
The rotation detection sensor 100 described above is effective when detecting backflow or detecting the rotation direction with a mechanical water flow meter, a wing for wind power generation, an axle of an automobile, or the like. FIG. 11 shows an example in which the principle of the rotation detection sensor 100 described above is used in a mechanical flow meter for water as a fluid measurement tachometer 200, which is shown as an embodiment.

The fluid measurement tachometer 200 has a casing 21 at the bottom and a housing 22 at the top. A cover 23 is placed on the upper side of the housing 21, and the display 25 and the like in the housing 21 can be seen through the transparent window 24 provided on the cover 23. The circuit board 26 and the like are also housed in the housing 21.

The casing 21 has an introduction port 21a for introducing the fluid to be measured, a discharge port 21b for discharging the fluid to be measured introduced from the introduction port 21a, and a discharge port 21b for discharging the fluid to be measured, as shown in FIG. It is provided with a flow path 21c that communicates the introduction port 21a and the discharge port 21b. An impeller 27 is provided in the flow path 21c. The impeller 27 receives the flow of the fluid to be measured flowing in the flow path 1c and rotates about the axis J of the rotation shaft. It is desirable that the material of the casing 21 is a non-magnetic material, and a part such as the rotating shaft of the impeller 27 may be outside the casing 21.

A pair of magnets 12-1 and 12-2 are embedded in the blades 27a and 27b of the impeller 27, and in the magnetic field B generated by the magnets 12-1 and 12-2 (with the rotation axis of the impeller 27). Magnetic sensors 13-1 and 13-2 are fixedly installed in (in orthogonal planes) with a rotational position shift δ (δ ≠ nπ / 4 (n is an integer)). In this example, the centers of the magnetic sensors 13-1 and 13-2 are aligned with the axis J of the rotation axis of the impeller 27, and the magnetic sensor 13-1 and the magnetic sensor 13-2 are vertically spaced parallel to each other. It is installed in the housing 22 on the outside of the casing 21 so as to be stacked with each other. Further, in the housing 22, a magnetic shield 28 is provided between the magnetic sensors 13-1 and 13-2 and the circuit board 26. The cross-sectional view shown in FIG. 12 shows the positional relationship of the magnetic sensors 13-1 and 13-2 with respect to the impeller 27.

In the fluid measurement tachometer 200, when the impeller 27 rotates, the detection output V1 (θ) of the magnetic sensor 13-1 and the detection output V2 (θ) of the magnetic sensor 13-2 increase or decrease (see FIG. 13). In this case, since the magnetic sensors 13-1 and 13-2 are installed with a rotational position deviation δ, the detection output V1 (θ) of the magnetic sensor 13-1 and the detection output V2 of the magnetic sensor 13-2 A phase difference occurs with (θ), the magnetic sensor 13-1 outputs a detection output of V1 (θ) = V1p · cos (2θ), and the magnetic sensor 13-2 outputs V2 (θ) = V2p · cos. The detection output of (2 (θ-δ)) is output.

Also in this embodiment, as in the rotation detection sensor 100, V2p> V1p (V2p = V1p / cos (2δ)), and the detection output V1 (θ) generated by the magnetic sensor 13-1 and the magnetic sensor 13-2 It is assumed that the detected output V2 (θ) to be generated intersects at the point of V1 (θ) = V1p.

With such a configuration, similarly to the rotation detection sensor 100, the detection output V1 (θ) of the magnetic sensor 13-1 and the detection output V2 (θ) of the magnetic sensor 13-2 all around the impeller 27. It becomes possible to detect the rotation direction over.

FIG. 14 shows an outline of the calculation unit 29 attached to the fluid measurement tachometer 200. The calculation unit 29 has a rotation information detection unit 30 that detects the rotation information of the impeller 27, and a desired measurement result regarding the fluid to be measured based on the rotation information of the impeller 27 detected by the rotation information detection unit 30. For example, it is provided with a fluid measuring unit 31 for obtaining the flow rate and flow velocity of the fluid to be measured). The arithmetic unit 29 is built on a circuit board 26 in a housing 22, and is realized by hardware including a processor and a storage device, and a program that realizes various functions in cooperation with these hardware. ..

In the calculation unit 29, the rotation information detection unit 30 has the same configuration as the rotation information detection unit 14 shown in FIG. 4, and the increase / decrease tendency of the detection output V1 (θ) of the magnetic sensor 13-1 is dV1 / dt ( The first differential circuit 30-1 that detects as the positive / negative of the tangent slope) and the second that detects the increasing / decreasing tendency of the detection output V2 (θ) of the magnetic sensor 13-2 as the positive / negative of dV2 / dt (tangent slope). 30-2, a comparison circuit 30-3 for comparing the magnitude of the detection output V1 (θ) of the magnetic sensor 13-1 and the detection output V2 (θ) of the magnetic sensor 13-2, and the differential circuit 30-1. , 30-2, and the comparison circuit 30-3, and the magnetometer 13-1's detection output V1 (θ), the rotation direction determination unit 30-determines the rotation direction of the impeller 27. 4 and the number of times the impeller 27 has rotated in the forward direction from the rotation reference position based on the determination result of the rotation direction by the rotation direction determination unit 30-4 and the detection output V1 (θ) of the magnetic sensor 13-1. The number of rotations of the impeller 27 and the magnetic sensor 13-counted by the number of rotations counting unit 30-5, which counts the number of rotations of the impeller 27 as the difference from the number of times of rotation in the opposite direction. It is provided with a rotation angle calculation unit 30-6 for obtaining the rotation angle of the impeller 27 from the rotation reference position based on the detection output V1 (θ) of 1.

FIG. 15 shows the rotation direction determination condition used by the rotation direction determination unit 30-4 and the rotation speed count condition used by the rotation speed counting unit 30-5.

Condition 1 of the rotation direction determination unit 30-4 is that when the slope “dV1 / dt” of the tangent line of V1 (θ) is positive (rising), “V1 (θ) −V2 (θ)” is positive. As a condition 2, the impeller 27 is positive under the condition that "V1 (θ) -V2 (θ)" is negative when the slope "dV1 / dt" of the tangent line of V1 (θ) is negative (descending). Judge that it is rotating.

Further, when the slope "dV1 / dt" of the tangent line of V1 (θ) is zero and "V1 (θ) -V2 (θ)" is zero, V1 (θ) is the maximum tangent line of V2 (θ). When the slope "dV2 / dt" of V1 (θ) is positive (rise), and the slope "dV2 / dt" of the tangent line of V1 (θ) is the minimum and V2 (θ) is negative (fall). Is a condition 4, and it is determined that the impeller 27 is rotating in the forward direction.

Further, the rotation direction determination unit 14-4 determines that “V1 (θ) −V2 (θ)” is positive when the slope “dV1 / dt” of the tangent line of V1 (θ) is negative (downward). As a condition 5, the impeller 27 is a condition 6 when the slope “dV1 / dt” of the tangent line of V1 (θ) is positive (rising) and “V1 (θ) −V2 (θ)” is negative. Is determined to be rotating in the reverse direction.

Further, when the slope "dV1 / dt" of the tangent line of V1 (θ) is zero and "V1 (θ) -V2 (θ)" is zero, V1 (θ) is the maximum tangent line of V2 (θ). When the slope "dV2 / dt" of V1 (θ) is negative (downward), and when V1 (θ) is the minimum and the slope "dV2 / dt" of the tangent of V2 (θ) is positive (rise) Is a condition 8, and it is determined that the impeller 27 is rotating in the reverse direction.

The rotation speed counting unit 30-5 counts the number of rotations of the impeller 27 when the detection output V1 (θ) of the magnetic sensor 13-1 reaches the minimum amplitude when the impeller 27 is rotating forward. When the impeller 27 is rotating in the reverse direction, the number of rotations of the impeller 27 is -0.5 when the detection output V1 (θ) of the magnetic sensor 13-1 reaches the minimum amplitude. And. The count condition for the number of rotations is an example, and other possibilities can be considered.

16A and 13B are magnetic sensors in the case where the impeller 27, which has started to rotate forward from the PA point, changes direction at the PB point, rotates in the reverse direction to the PC point, and then returns to the forward rotation again. The change of the number of rotations N of the impeller 27 counted as the change of the detection outputs V1 (θ) and V2 (θ) of 13-1 and 13-2 is shown. For reference, in FIG. 17, the change in the sign (positive / negative) of the slope “dV1 / dt” of the tangent line of V1 (θ) and the change in the sign (positive / negative) of “V1 (θ) −V2 (θ)” at this time. Is shown.

The rotation angle calculation unit 30-6 determines the current rotation of the impeller 27 from the rotation speed N of the impeller 27 counted by the rotation speed counting unit 30-5 and the detection output V1 (θ) of the magnetic sensor 13-1. Calculate the angle θ. FIG. 18 shows the rotation angle θ'of the impeller 27 calculated by the rotation angle calculation unit 30-6 in comparison with the actual rotation angle θ. In FIG. 18, N (θ) indicates a rotation angle obtained as the number of rotations N × 360 ° of the impeller 27.

In this way, the rotation information detection unit 30 detects the rotation direction, the number of rotations, and the rotation angle of the impeller 27 as the rotation information of the impeller 27, and the rotation information of the detected impeller 27 is the fluid measurement unit 31. Will be sent to. The fluid measurement unit 31 obtains the flow rate, the flow velocity, etc. of the fluid to be measured as a measurement result based on the rotation information of the impeller 27 sent from the rotation information detection unit 30. In this case, since the rotation direction is detected over the entire circumference of the impeller 27, the measurement accuracy of the flow rate and the flow velocity of the fluid to be measured can be improved.

In this embodiment, the magnetic sensors 13-1 and 13-2 are installed so as to overlap each other in the housing 22, but as shown in FIG. 19, for example, the magnetic sensor 13- sandwiches the casing 21. The magnetic sensor 13-2 may be installed facing the opposite side of 1. In this case, the magnetic sensor 13-2 is covered with the sensor housing 32, and the magnetic sensor 13-2 and the circuit board 26 in the housing 22 are connected by the wiring 33.

Further, in the above-described first and second embodiments, the magnetic sensors 13-1 and 13-2 are angle sensors using a magnetoresistive element (MR element), but an angle sensor using a Hall element may be used.

[Extension of Embodiment]
Although the present invention has been described above with reference to the embodiments, the present invention is not limited to the above embodiments. Various changes that can be understood by those skilled in the art can be made to the structure and details of the present invention within the scope of the technical idea of the present invention.

11 ... Rotating body, 12-1, 12-12 ... Magnet, 13-1, 13-2 ... Magnetic sensor, 14 ... Rotation information detector, 14-1 ... First differentiating circuit, 14-2 ... Second Differentiator circuit, 14-3 ... Comparison circuit, 14-4 ... Rotation direction determination unit, 14-5 ... Rotation speed counting unit, 14-6 ... Rotation angle calculation unit, 21 ... Casing, 22 ... Housing, 26 ... Circuit board, 27 ... impeller, 28 ... magnetic shield, 29 ... calculation unit, 30 ... rotation information detection unit, 30-1 ... first differentiating circuit, 30-2 ... second differentiating circuit, 30-3 ... comparison circuit, 30 -4 ... Rotation direction determination unit, 30-5 ... Rotation speed count unit, 30-6 ... Rotation angle calculation unit, 31 ... Fluid measurement unit, 100 ... Rotation detection sensor, 200 ... Fluid measurement rotator (for mechanical water) Flowmeter).

Claims (7)

An introduction port for introducing the fluid to be measured, a discharge port for discharging the fluid to be measured introduced from the introduction port, and a flow path for communicating the introduction port and the discharge port are provided, and the inside of the flow path is provided. A casing incorporating an impeller that rotates about a rotation axis in response to the flow of the fluid to be measured, and a magnetic field generating unit that generates a magnetic field whose direction changes with the rotation of the impeller.
A first magnetic sensor that is fixedly installed in a magnetic field outside the casing generated by the magnetic field generating unit and whose detection output changes in conjunction with a change in the direction of the magnetic field accompanying rotation of the impeller.
It is fixedly installed in the magnetic field outside the casing generated by the magnetic field generating unit with a rotational position shift δ with respect to the first magnetic sensor, and changes in the direction of the magnetic field due to the rotation of the impeller. A second magnetic sensor whose detection output changes in conjunction with it,
The detection output of the first magnetic sensor is defined as the first detection output, the detection output of the second magnetic sensor is defined as the second detection output, and at least the above is based on the first detection output and the second detection output. A rotation information detection unit that detects the rotation direction of the impeller as rotation information of the impeller, and a desired measurement result regarding the fluid to be measured are obtained based on the rotation information of the impeller detected by the rotation information detection unit. It is equipped with a housing that incorporates a fluid measurement unit as a calculation unit.
The first magnetic sensor is
When the rotation angle of the magnetic field accompanying the rotation of the impeller is θ and the maximum value of the first detection output is V1p, the voltage of V1 (θ) = V1p · cos (2θ) as the first detection output. To generate
The second magnetic sensor is
When the rotation angle of the magnetic field accompanying the rotation of the impeller is θ and the maximum value of the second detection output is V2p, V2 (θ) = V2p · cos (2 (θ-)) as the second detection output. δ))), generate a voltage
The first detection output V1 (θ) generated by the first magnetic sensor and the second detection output V2 (θ) generated by the second magnetic sensor are
The maximum value V2p of the second detection output V2 (θ) is larger than the maximum value V1p of the first detection output V1 (θ), and intersects at the point where V1 (θ) = V1p. Fluid measurement tachometer. In the fluid measurement tachometer according to claim 1,
The first magnetic sensor is
It is installed in a first plane orthogonal to the rotation axis of the impeller so that its center coincides with the axis of the rotation axis of the impeller.
The second magnetic sensor is
It is installed in a second plane orthogonal to the rotation axis of the impeller so that its center is aligned with the axis of rotation of the impeller.
The first and second magnetic sensors are
Built in the housing together with the arithmetic unit
A fluid measurement tachometer characterized in that a magnetic shield is provided between the first and second magnetic sensors and the calculation unit. In the fluid measurement tachometer according to claim 1,
The first magnetic sensor is
It is installed in a first plane orthogonal to the rotation axis of the impeller so that its center coincides with the axis of the rotation axis of the impeller.
The second magnetic sensor is
It is installed in a second plane orthogonal to the rotation axis of the impeller so that its center is aligned with the axis of the rotation axis of the impeller.
The first magnetic sensor is
Built in the housing together with the arithmetic unit
The second magnetic sensor is
It is installed facing the opposite side of the first magnetic sensor with the casing in between.
A fluid measurement tachometer characterized in that a magnetic shield is provided between the first magnetic sensor and the calculation unit. In the fluid measurement tachometer according to claim 1,
The second detection output V2 (θ) generated by the second magnetic sensor is
A fluid measurement tachometer characterized in that the maximum value V2p is V2p = V1p / cos (2δ). In the fluid measurement tachometer according to claim 1,
The rotation information detection unit
The direction of rotation of the impeller based on the increasing / decreasing tendency of the first detection output V1 (θ) and the magnitude relationship between the first detection output V1 (θ) and the second detection output V2 (θ). A fluid measurement tachometer characterized by detecting. In the fluid measurement tachometer according to claim 5.
The rotation information detection unit
A fluid measurement tachometer characterized in that the number of rotations of the impeller is counted as the difference between the number of times the impeller has rotated in the forward direction and the number of times the impeller has rotated in the opposite direction from the rotation reference position. In the fluid measurement tachometer according to claim 6.
The rotation information detection unit
Fluid measurement rotation characterized in that the rotation angle of the impeller from the rotation reference position is obtained based on the detected rotation direction of the impeller, the number of rotations of the impeller counted, and the first detection output. Total.

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