JP5240888B2 - Motion detection device - Google Patents

Description

  The present invention relates to a motion detection device, and more particularly to a motion detection device that detects the rotational speed, rotational speed, or rotational acceleration of a turbocharger.

  2. Description of the Related Art Conventionally, there has been known a motion detection device including a coil that generates a magnetic field and a conductive detection target that is linked to a detection target (see, for example, Patent Documents 1 and 2). In such a motion detection device, the motion of the detection target is detected by detecting a change in the inductance of the coil accompanying the motion of the detected portion. For example, in the motion detection devices disclosed in Patent Documents 1 and 2, a detection target is provided by detecting a change in the inductance of a coil provided with a rotor as a detected part and a convex part of the rotor passing near the coil. Detecting movement.

  However, in the motion detection devices disclosed in Patent Documents 1 and 2, when the width of the convex portion in the rotation direction is narrowed, the passage period in which the convex portion passes in the vicinity of the coil is shortened. Then, since the change of the output signal due to the inductance change of the coil and the change of the output signal due to the noise cannot be separated, the movement of the rotor cannot be accurately detected. Can no longer be detected. Therefore, even if the detection target has a conductive portion corresponding to the convex portion of the rotor, if the width of the movement direction of the detection target of the conductive portion is narrow, the detection target conductive portion is moved as the detected portion. The configuration of the detection device cannot be simplified.

JP 2000-97958 A JP 2000-121655 A

  The present invention has been made to solve the above-described problems, and an object thereof is to provide a motion detection device having a simple configuration that can accurately detect the motion of a detection target.

In the invention according to claims 1 to 5 , in order to detect the motion of the detection target by the detected portion provided in the detection target, compared to a motion detection device including a motion detection rotor separately from the detection target, The configuration of the motion detection device can be simplified. As a result, for example, the manufacturing cost of the motion detection device can be reduced, or the motion detection device can be downsized. Specifically, for example, in the motion detection device that detects the rotational motion of the turbocharger, the configuration can be simplified by detecting the rotational motion of the turbocharger using the turbine blade as the detected portion.
In the inventions according to claims 1 to 5 , since the detected part is inclined with respect to the movement direction of the detection target, the passing period during which the detected part passes in the vicinity of the coil is extended. As a result, the detected portion can be accurately detected, and the motion of the detection target can be accurately detected. The motion of the detection target detected by the motion detection device according to the present invention is a physical quantity that correlates with the motion speed of the detection target. For example, when the detection target is a rotating body, the rotation speed, the rotation speed, the rotation acceleration, etc. is there.

When the motion speed of the detection target is increased, it becomes difficult to accurately detect the motion of the detection target because the passing period in which the detected portion passes near the coil is shortened. However, according to the first to fifth aspects of the present invention , the “part where the motion is detected” with respect to the motion direction of the detection target with respect to the “ part where the motion is detected” among the detected parts. the inclination angle of the "theta, an interval direction of movement between the" site motion is detected, "adjacent the Y together, when the diameter of the coil is D, the coil is set such that sinθ = (2D / Y) Has been.
As a result, the passage period in which the detected part passes through the vicinity of the coil and the non-passing period are substantially the same. As a result, even if the motion speed of the detection target increases, the detected portion can be detected accurately, so that the motion of the detection target can be detected accurately.

In the invention described in claim 2 , the detection target is a rotating body. Therefore, it is possible to realize a motion detection device easy disjoint configuration capable of accurately detecting the rotational movement of the detection target.

According to the third to fourth aspects of the present invention, the detection target is a turbocharger, and the detected portion is a part of a turbine blade or a compressor blade of the turbocharger. Therefore, it is possible to realize a motion detection device easy disjoint configuration capable of accurately detecting the rotational movement of the turbocharger.

In the invention according to claim 4 , the detected portion is a radial end portion of a turbocharger of a turbine blade or a compressor blade. That is, since the coil is disposed outside the turbocharger in the radial direction, the coil does not hinder the intake and exhaust of the turbocharger.

According to the fifth aspect of the present invention, it is possible to detect the rotational speed, rotational speed, or rotational acceleration of the detection target based on the number of times that the detected portion passes the vicinity of the coil in a predetermined unit time.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
FIG. 1 is a schematic diagram for explaining a motion detection device according to an embodiment of the present invention. A motion detection device 1 according to an embodiment of the present invention is a device that detects the rotational speed of a turbocharger 2 as a detection target.

The turbocharger 2 is a turbine wheel 10 that is rotationally driven by the exhaust gas flow of the engine, a compressor wheel (not shown) that rotates together with the turbine wheel 10 and pressurizes intake air, a rotary shaft 11 that connects the turbine wheel 10 and the compressor wheel, It consists of a housing, a control device, etc. that do not.
The turbine wheel 10 and the compressor wheel are provided with fin-like turbine blades 12 and compressor blades, respectively. Hereinafter, the configuration and operation of the motion detection device 1 will be described in this order.

(Configuration of motion detection device)
The motion detection device 1 includes a turbine blade 12, a coil 20, a detection unit 30, a control device for the turbocharger 2, and the like.
The turbine blade 12 is a conductor such as aluminum. The turbine blade 12 has a fin shape with a narrow width in the rotational direction of the turbocharger 2 and protrudes from the base portion 14 of the turbine wheel 10. The turbine blade 12 is twisted in the vicinity of the tip 14 a of the base portion 14 and is inclined with respect to the rotation direction of the turbocharger 2. Hereinafter, a portion of the turbine blade 12 that is inclined with respect to the rotation direction of the turbocharger 2 is referred to as an inclined portion 12a.

  The coil 20 has a posture in which the end 20a in the central axis direction faces the turbocharger 2, and the radial end of the turbocharger 2 of the inclined portion 12a passes through the vicinity as the turbocharger 2 rotates. Has been placed. In this case, the end of the inclined portion 12a in the radial direction of the turbocharger 2 corresponds to the “detected portion” described in the claims. Specifically, for example, the coil 20 is inserted into the resin 22 and attached to the housing of the turbocharger 2. The resin 22 protects the coil 20 and is not always necessary.

FIG. 2 is a circuit diagram showing the coil 20 and the detection unit 30.
The detection unit 30 as detection means generates a magnetic field by driving the coil 20, and detects an inductance change of the coil 20 when the inclined portion 12 a passes near the coil 20. The detection unit 30 is connected to the above-described control device of the turbocharger 2.

  Specifically, for example, the detection unit 30 includes an oscillator 32, a capacitor 34, a resistor 36, an envelope detection circuit (not shown), a comparator, and the like. The coil 20 and the capacitor 34 form a parallel resonance circuit, and the resistor 36 is connected in series to the resonance circuit. The oscillator 32 drives a circuit constituted by a resonance circuit and a resistor 36 with an alternating current. The input end of the envelope detection circuit is connected to a contact 38 of the coil 20, capacitor 34, and resistor 36 of the resonance circuit. The input terminal of the comparator is connected to the output terminal of the envelope detection circuit.

(Activation of motion detection device)
When the oscillator 32 of the detection unit 30 drives the coil 20, a magnetic field is generated by the coil 20. When the turbocharger 2 rotates, the turbine blade 12 passes near the coil 20. Since the magnetic flux density in the vicinity of the coil 20 is high, a large eddy current is generated in the turbine blade 12 when the turbine blade 12 passes through the vicinity of the coil 20 and the magnetic flux generated by the coil 20 passes through the turbine blade 12. . On the other hand, almost no eddy current is generated in the turbine blade 12 during the non-passing period of the turbine blade 12.

  Since this eddy current flows in a direction that cancels the change in the magnetic field caused by the coil 20, the inductance of the coil 20 is affected. As a result, the impedance of the coil 20 changes greatly between the passing period and the non-passing period of the turbine blade 12, and the resonance frequency of the resonance circuit described above changes greatly between both periods. As the resonance frequency of the resonance circuit changes in this way, the potential amplitude of the contact 38 changes.

  Specifically, for example, when the oscillator 32 is transmitted in the vicinity of the resonance frequency in the non-passage period of the resonance circuit, the resonance circuit is shifted from the resonance frequency during the passage period of the turbine blade 12 as shown in FIG. When the impedance of the resonance circuit is reduced by being driven by the alternating current, the potential amplitude of the contact 38 during the passage period is increased. On the other hand, during the non-passing period of the turbine blade 12, the resonance circuit is driven by an alternating current having a resonance frequency and the impedance of the resonance circuit is increased, so that the potential amplitude of the contact 38 in the non-passing period is reduced.

  As shown in FIG. 3B, the envelope detection circuit detects an envelope of potential oscillation of the contact 38. Then, as shown in FIG. 3C, the comparator converts an analog signal indicating an envelope of potential oscillation of the contact 38 into a digital signal (hereinafter referred to as a detection signal) with a predetermined threshold, and the detection signal is converted into a turbocharger. 2 to the control device. The control device of the turbocharger 2 detects the rotation speed of the turbocharger 2 by detecting the motion of the turbine blade 12 based on the digital signal output from the comparator. Specifically, the control device detects the rotational speed of the turbocharger 2 from the number of times the turbine blade 12 passes through the coil 20 in a predetermined unit time and the number of turbine blades 12 provided in the turbine wheel 10. . The control device at this time functions as detection means.

  As described above, the motion detection device 1 has a configuration compared to a motion detection device including a motion detection rotor that is linked to the turbocharger 2 by detecting the rotational speed of the turbocharger 2 using the turbine blade 12. It has been simplified. That is, according to the present invention, since the configuration of the motion detection device can be simplified, the manufacturing cost of the motion detection device can be reduced or the motion detection device can be downsized.

  FIG. 4 is a schematic diagram for explaining the passage period of the turbine blade 12. FIG. 5 is a schematic diagram showing a motion detection device 100 as a comparative example. 4A shows a passage period (t1 to t4) in the motion detection apparatus 1, and FIG. 4B shows a passage period (t2 to t3) in the movement detection apparatus 100 of the comparative example. A region 50 indicated by a dotted line in FIG. 4 indicates a region where the magnetic flux density by the coil 20 is high. In the motion detection apparatus 100 as a comparative example shown in FIG. 5, the coil 20 is arranged so that the orthogonal part 12 b of the turbine blade 12 passes in the vicinity of the coil 20. Here, the orthogonal part 12 b is a part orthogonal to the rotational direction of the turbocharger 2 of the turbine blade 12.

  As is clear from FIG. 4, by arranging the coil 20 so that the inclined portion 12 a passes through the vicinity of the coil 20 in accordance with the rotational motion of the turbine wheel 10, In comparison, the passage period of the turbine blade 12 can be extended.

  Here, generally, when the rotational speed of the turbocharger 2 is detected using the turbine blade 12 of the turbocharger 2, the passage period of the turbine blade 12 is shorter than the non-passage period. Therefore, as described above, the motion detection apparatus 1 can accurately detect the motion of the turbine blade 12 by extending the passage time of the turbine blade 12 to increase the signal width indicating the passage time of the detection signal. Specifically, by widening the signal width indicating the passage period of the detection signal, the noise can be easily separated from the detection signal even when noise with a narrow pulse width is superimposed on the detection signal.

FIG. 6 is a schematic diagram showing a detection signal of the motion detection device 1, and shows a detection signal when the turbocharger 2 is rotating at a constant speed.
In the detection signal shown in FIG. 6, the signal width indicating the passage period of the turbine blade 12 and the signal width indicating the non-passage period of the turbine blade 12 are substantially the same. According to such a detection signal, even if the cycle of the detection signal is shortened, that is, the rotational speed of the turbocharger 2 is increased, the signal width indicating the passage period of the turbine blade 12 and the non-passage period of the turbine blade 12 It is possible to prevent any one of the signal widths indicating N from narrowing with respect to the other. As a result, even if the rotational speed of the turbine blade 12 increases, the motion detection device 1 can accurately detect the motion of the turbine blade 12.

FIG. 7 is a schematic diagram showing a design method for obtaining a detection signal as shown in FIG. 6 in the motion detection device 1.
The cycle of the detection signal correlates with the movement direction interval Y between the inclined portions 12 a adjacent to each other of the plurality of turbine blades 12. Therefore, in order to obtain a detection signal as shown in FIG. 6, it is necessary to make the “signal width indicating the passage period of the detection signal” a half cycle of the detection signal. That is, the motion detection device 1 so that the relationship represented by the following expression (1) is established between the “ distance Z 2 at which the inclined portion 12a moves to the signal width indicating the passage period of the detection signal ” and the interval Y between the inclined portions 12a. Need to design.

  Here, as shown in FIG. 7, the distance X that the inclined portion 12a moves during the period in which the impedance of the coil 20 changes is the angle D formed by the coil diameter D and the rotational direction of the turbocharger 2 of the inclined portion 12a. Is represented by the following formula (2).

On the other hand, the following equation (3) between the distance X and the distance Z is established.
X = Z (3)

Therefore, the angle θ formed with respect to the rotation direction of the turbocharger 2 of the inclined portion 12a is expressed by the following equation (4).
sin θ = (2D / Y) (4)

That is, by arranging the coil 20 in the vicinity of the inclined portion 12a that forms an angle of the expression (4) with respect to the rotation direction of the turbocharger 2, the signal width indicating the passage period of the turbine blade 12 and the non-rotation of the turbine blade 12 are determined. A detection signal having the same signal width indicating the passage period can be obtained.

In one embodiment of the present invention described above, by detecting the rotational speed of the turbocharger 2 using the turbine blade 12, as compared with a motion detection device including a motion detection rotor linked to the turbocharger 2, The configuration of the motion detection device 1 can be simplified.
Further, the motion detection device 1 can accurately detect the turbine blade 12 that is the detection target as described above.

(Other embodiments)
In the embodiment according to the present invention, the motion detection device 1 is described as detecting the rotational speed of the turbocharger 2, but the detection target is not limited to the turbocharger 2. For example, the detection target may be a turbocharger having a different configuration from the turbocharger 2, another turbine different from the turbocharger 2, or a translational motion other than the rotational motion. The physical quantity detected by the motion detection device 1 may be a rotational speed or a rotational acceleration.

  Further, the motion detection device 1 has been described as detecting the rotational speed of the turbocharger 2 using the end portion of the inclined portion 12a in the radial direction of the turbocharger 2 as a detected portion. However, in the motion detection device 1, a portion that is inclined with respect to the rotation direction of the turbocharger 2 of the turbine blade 12 and that is different from the above-described end portion of the inclined portion 12 a may be the detected portion, or the inclined portion of the compressor blade. May be the detected part.

Also, although the control unit of the detection circuit and the turbocharger 2 has been described to function as a detecting means, the detection means may be constituted by a single unit or may be constituted by three or more units.

Further, the signal width indicating the passage period of the detection signal and the signal width indicating the non-passing period may be different as long as the turbine blade 12 can detect accurately.
The present invention is not limited to the above-described embodiment, and can be applied to various embodiments without departing from the gist thereof.

The schematic diagram for demonstrating the motion detection apparatus by one Embodiment of this invention. The schematic diagram which shows the coil and detection part which concern on one Embodiment of this invention. The schematic diagram for demonstrating the detection part which concerns on one Embodiment of this invention. The schematic diagram for demonstrating the passage period of a turbine blade. The schematic diagram which shows the comparative example of this invention. The schematic diagram which shows the output signal of the detection part which concerns on one Embodiment of this invention. The schematic diagram for demonstrating the design method of the motion detection apparatus by one Embodiment of this invention.

Explanation of symbols

1: motion detector, 2: turbocharger (detection target), 12: turbine blade, 12a: inclined part (detected part), 20: coil, 30: detection part (detection means)

Claims (5)

A motion detection device for detecting a motion of a detection target,
A plurality of conductive to-be-detected parts arranged in the movement direction of the detection target;
A coil that generates a magnetic field and is arranged with its end in the central axis direction facing the detection target so that the detection target passes through the vicinity with the movement of the detection target;
Detecting means for detecting movement of the detection object by detecting a change in inductance of the coil accompanying the detected portion passing through the vicinity of the coil;
The detected portion has a fin shape with a narrow width in the movement direction of the detection target at the end on the coil side, and is provided to be inclined with respect to the movement direction of the detection target.
Among the detected parts, with respect to a portion that passes in the vicinity of the coil and the motion is detected, an inclination angle of the portion where the motion is detected with respect to the motion direction of the detection target is θ, and the motions adjacent to each other are When the interval in the direction of motion between the detected parts is Y and the diameter of the coil is D,
sin θ = (2D / Y)
A motion detection device in which the coil is set to be The detection object rotates,
The motion detection apparatus according to claim 1, wherein the detected part is inclined with respect to a rotation direction of the detection target. The detection target is a turbocharger,
The motion detection device according to claim 2, wherein the detected part is a part of a turbine blade or a compressor blade of the turbocharger.   The motion detection device according to claim 3, wherein the detected portion is an end portion in a radial direction of the turbocharger of the turbine blade or the compressor blade. The detection object rotates,
5. The detection unit according to claim 1, wherein the detection unit detects a rotation speed, a rotation speed, or a rotation acceleration of the detection target based on the number of times that the detected portion passes through the vicinity of the coil in a predetermined unit time. The motion detection device according to one item.

Images