JP2019203868A - Turbocharger - Google Patents

Abstract

To provide a turbocharger which is less susceptible to the effect of extraneous noise, and with which it is possible to detect the revolution speed of a compressor wheel with good accuracy without having to projecting a sensor unit to an exhaust passage.SOLUTION: The turbocharger comprises: a magnet 2 rotating integrally with a compressor wheel 17 that is driven to rotate by the rotation of a turbine wheel 20, and having a plurality of magnetic poles in the circumferential direction; and a sensor unit 3 attached to a compressor housing 15 that accommodates the compressor wheel 17 and having a first and a second magnetism detection element 31A, 31B capable of detecting a magnetic field due to the magnet 2 in the radial direction of the compressor wheel 17. The first and second magnetism detection elements 31A, 31B are arranged side by side in the radial direction of the compressor wheel 17, and it is possible to measure the revolution speed of the compressor wheel 17 on the basis of a difference in the detection results of the first and second magnetism detection elements 31A, 31B that occurs due to a difference in the distance to the magnet 2.SELECTED DRAWING: Figure 5

Description

  The present invention relates to a turbocharger.

  Conventionally, as a turbo rotation sensor for detecting the rotation speed of a turbocharger mounted on a vehicle, a turbocharger has been provided which has a magnet that rotates integrally with a compressor wheel and detects a change in the magnetic field by the magnet by a magnetic detection element. Is known that detects the rotation speed (number of rotations) (see, for example, Patent Document 1).

Special table 2008-506074

  In the turbo rotation sensor using the magnet and the magnetic detection element as described above, the magnetic detection element detects, for example, an external magnetic field derived from various control devices. In some cases, the rotation speed of the charger cannot be accurately detected. Therefore, a turbo rotation sensor that is not easily affected by external noise is desired.

  In addition, for example, if a sensor unit or the like equipped with a magnetic detection element is projected into the intake passage, the performance of the turbocharger may deteriorate due to the obstruction of intake air, or the pressure of intake air may adversely affect the sensor unit. Therefore, it can be said that the sensor unit is preferably provided so as not to protrude into the intake passage. However, in this case, the distance between the magnetic detection element and the magnet is increased, and the detection accuracy may be reduced. Therefore, a turbocharger that can accurately detect the rotation speed of the compressor wheel without causing the sensor portion to protrude into the intake passage is desired.

  Therefore, an object of the present invention is to provide a turbocharger that is not easily affected by external noise and that can accurately detect the rotational speed of the compressor wheel without causing the sensor portion to protrude into the intake passage.

  For the purpose of solving the above-mentioned problems, the present invention provides a compressor in which a compressor wheel that is rotationally driven is accommodated in a compressor housing, a magnet that rotates integrally with the compressor wheel, and has a plurality of magnetic poles in the circumferential direction. And a sensor unit having first and second magnetic detection elements attached to the compressor housing and capable of detecting a radial magnetic field of the compressor wheel by the magnet, and the first and second magnetic detection elements Are arranged side by side in the radial direction of the compressor wheel, and the rotational speed of the compressor wheel is based on the difference between the detection results of the first and second magnetic detection elements generated by the difference in distance from the magnet. Provide a turbocharger that can measure

  According to the present invention, it is possible to provide a turbocharger that is not easily affected by external noise and that can accurately detect the rotation speed of the compressor wheel without causing the sensor unit to protrude into the intake passage.

It is a schematic block diagram of the turbocharger carrying the turbo rotation sensor which concerns on one embodiment of this invention. It is a perspective view of a compressor wheel. It is a figure which shows a magnet, (a) is a perspective view, (b) is a top view, (c) is a side view. (A) is a perspective view of a sensor part, (b) is a perspective view of a sensor module. It is a figure explaining the positional relationship of a magnetic detection element and a magnet. (A) is the schematic which shows the structure of the turbo rotation sensor which concerns on embodiment, (b) is the schematic which shows the structure of the turbo rotation sensor which concerns on a comparative example. (A) is a graph which shows the detection result of the 1st and 2nd magnetic detection element of the turbo rotation sensor which concerns on embodiment, and its difference, (b) is the 1st of the turbo rotation sensor which concerns on a comparative example. 4 is a graph showing detection results of the second magnetic detection element and a difference between them.

[Embodiment]
Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

(Description of turbocharger)
FIG. 1 is a schematic configuration diagram of a turbocharger equipped with a turbo rotation sensor according to the present embodiment.

  As shown in FIG. 1, the turbocharger 10 includes a compressor 11 provided in an intake passage 13 of an internal combustion engine (not shown) of a vehicle, and a turbine 12 provided in an exhaust passage 14 of the internal combustion engine.

  The compressor 11 is configured by accommodating a compressor wheel 17 having a plurality of compressor blades 16 in a compressor housing 15. The turbine 12 is configured by accommodating a turbine wheel 20 having a plurality of turbine blades 19 in a turbine housing 18. The turbine 12 is configured to receive exhaust from the internal combustion engine with the turbine blades 19 and to drive the turbine wheel 20 to rotate.

  The compressor wheel 17 and the turbine wheel 20 are connected by a turbo shaft 21, and the compressor wheel 17 is configured to be rotationally driven by the rotation of the turbine wheel 20. As a result, the turbocharger 10 is configured so that the compressor wheel 17 is rotationally driven in accordance with the rotation of the turbine wheel 20 that is rotationally driven by exhaust from the internal combustion engine, thereby compressing the intake air and feeding it to the internal combustion engine. ing.

  The turbo shaft 21 is rotatably supported by a bearing housing 22 that connects the compressor housing 15 and the turbine housing 18. An oil passage 23 to which lubricating oil for lubricating and cooling the turboshaft 21 is supplied is formed in the bearing housing 22, and the heat on the turbine 12 side is caused by a cooling effect by the lubricating oil supplied to the oil passage 23. Is transmitted to the compressor 11 side.

  The compressor housing 15 is nonmagnetic and has electrical conductivity. In the present embodiment, the compressor wheel 17 including the compressor housing 15 and the compressor blades 16 is made of aluminum (or aluminum alloy). The compressor wheel 17 may be made of a nonmagnetic material such as resin.

  As shown in FIG. 2, the compressor wheel 17 has a side surface that is curved so that the diameter gradually increases from the distal end side (intake air inflow side, upper side in the drawing) to the proximal end side (turbine side, lower side in the drawing). A plurality of compressor blades 16 are integrally formed on the side surface of 17a so as to be inclined with respect to the axial direction. A through hole 17b into which the turbo shaft 21 is inserted and connected is formed at the center of the base body 17a. The base body 17a has a substantially disc-shaped base end portion 17c extending from the compressor blade 16 to the base end side (turbine side).

(Description of turbo rotation sensor 1)
The turbocharger 10 is equipped with a turbo rotation sensor 1 that detects the rotation speed of the turbocharger 10, that is, the rotation speed of the compressor wheel 17.

  The turbo rotation sensor 1 includes a magnet 2 provided to rotate integrally with the compressor wheel 17 at an intake side end (an end opposite to the turbine 12) of the compressor wheel 17, and a compressor wheel 17 by the magnet 2. Sensor section 3 having first and second magnetic detection elements 31A and 31B capable of detecting a radial magnetic field.

(Description of magnet 2)
As shown in FIGS. 3A to 3C, in the present embodiment, the magnet 2 includes a nut that is screwed to the turbo shaft 21 and fixes the compressor wheel 17 to the turbo shaft 21. That is, the magnet 2 in the present embodiment is obtained by magnetizing a nut for fixing the compressor wheel 17.

  In the magnet 2, two different magnetic poles (N pole and S pole) are magnetized in the circumferential direction around the rotation axis of the compressor wheel 17. The magnetization direction (magnetization direction) in the magnet 2 is a direction (radial direction) perpendicular to the axial direction of the rotation axis. As a result, the magnetic flux can be made to reach a position farther away from the magnet 2 in the radial direction, and the sensitivity of the turbo rotation sensor 1 can be improved. As the magnet 2, it is preferable to use a magnet having a large magnetic force and little demagnetization at a high temperature. In the present embodiment, an Fe—Cr—Co magnet (iron chrome cobalt magnet) is used as the magnet 2.

  In the present embodiment, the magnet 2 includes a tool locking portion 2a that locks the fastening tool, and a flange-shaped flange portion 2b that is integrally provided at an end portion in the axial direction of the tool locking portion 2a. And have. A screw hole 2c penetrating the magnet 2 is formed at the center of the magnet 2 in a cross section perpendicular to the axial direction, and the magnet 2 is formed in an annular shape as a whole. The end of the turbo shaft 21 is formed with a male screw portion (not shown) having a thread formed on the outer peripheral surface thereof. By screwing a screw hole 2c into the male screw portion, the magnet 2 is connected to the turbo shaft 21. And is fixed to the compressor wheel 17.

  Here, although the case where the tool latching | locking part 2a is formed in the hexagonal shape seeing from one (intake side) of an axial direction is demonstrated, the shape of the tool latching | locking part 2a is not limited to this. In the present embodiment, the maximum outer diameter (distance between opposing corners) d1 of the tool locking portion 2a is 8.1 mm, and the axial length L1 is 2.4 mm.

  The collar portion 2b is formed in a short columnar shape (short cylindrical shape). The outer diameter d2 of the flange portion 2b is larger than the maximum outer diameter d1 of the tool locking portion 2a. Here, the outer diameter d2 of the flange portion 2b is 9.0 mm, and the axial length L2 is 2.0 mm. The axial length of the entire magnet 2 is 4.4 mm.

(Description of sensor unit 3)
As shown in FIGS. 1 and 5, the sensor unit 3 is accommodated in a sensor hole 15 a as an accommodation hole formed in the compressor housing 15. In addition, illustration of the compressor wheel 17 is abbreviate | omitted in FIG. The sensor hole 15 a is formed at a position corresponding to the magnet 2 of the compressor housing 15 along the radial direction of the compressor wheel 17.

  In the present embodiment, the sensor hole 15 a is a blind hole formed so as not to penetrate the compressor housing 15, and opens to the outer surface of the compressor housing 15 and does not open to the inner surface of the compressor housing 15. Thereby, it becomes possible to suppress that the sensor part 3 is damaged by the pressure of intake air etc., and reliability improves. Here, the thickness h of the bottom wall 151 of the compressor housing 15 between the sensor hole 15a and the intake passage 13 is 1.0 mm.

  Considering the difference in thermal expansion between the materials constituting the sensor unit 3 and the compressor housing 15 in the usage environment, the tip of the sensor unit 3 is accommodated in the sensor hole 15 a so as to be close to the bottom wall 151 of the compressor housing 15. ing. The sensor part 3 is arranged so that the tip part thereof is aligned with the magnet 2 in the radial direction around the rotation axis of the compressor wheel 17 in a state of being accommodated in the sensor hole 15a. Note that the tip of the sensor unit 3 may be in contact with the bottom wall 151 of the compressor housing 15.

  First and second magnetic detection elements 31 </ b> A and 31 </ b> B are accommodated at the tip of the sensor unit 3 (the part indicated by the symbol A in FIG. 4A). The first magnetic detection element 31A and the second magnetic detection element 31B have the same magnetic field sensitivity. The first and second magnetic detection elements 31A and 31B are arranged side by side in the depth direction of the sensor hole 15a, that is, in the radial direction of the compressor wheel 17, and the first magnetic detection element 31A is the second magnetic detection element 31A. It is arranged closer to the bottom wall 151 side of the sensor hole 15a than the magnetic detection element 31B.

  As the first and second magnetic detection elements 31A and 31B, GMR (Giant Magneto-Resistive) sensors, Hall elements (Hall ICs), AMR (Anisotropic Magneto-Resistive) sensors, TMR (Tunneling Magneto-resistive) sensors, etc. Can be used. In the present embodiment, the first and second magnetic detection elements 31A and 31B are GMR sensors, and a multilayer film in which a ferromagnetic thin film (F layer) and a non-ferromagnetic thin film (NF layer) are stacked is used as a magnetic field detection unit. Have.

  The first and second magnetic detection elements 31 </ b> A and 31 </ b> B are built in the sensor module 32. The sensor module 32 outputs an electrical signal corresponding to the difference between the magnetic field detection results of the first and second magnetic detection elements 31A and 31B. The sensor module 32 is covered with a sensor housing 33 made of mold resin. In the present embodiment, the sensor housing 33 is formed in a substantially cylindrical shape. The sensor housing 33 is integrally provided with a fixing flange 331 for attaching the sensor unit 3 to the compressor housing 15. The shape of the sensor housing 33 is an example, and is not limited to the illustrated example.

  A signal line 34 for outputting an electrical signal from the sensor module 32 is extended from the base end portion of the sensor housing 33. From the sensor module 32, a lead wire 35 that outputs an electric signal corresponding to the difference between the magnetic field detection results of the first and second magnetic detection elements 31A and 31B is extended. 34 core wires (not shown) are electrically connected in the sensor housing 33 by resistance welding or the like.

  The front end portion of the signal line 34 extended from the sensor unit 3 is connected to an ECU (electronic control unit) of a vehicle (not shown). In this ECU, the rotation speed of the compressor wheel 17 based on the electric signal from the sensor unit 3, that is, the electric signal corresponding to the difference between the magnetic field detection results of the first and second magnetic detection elements 31A and 31B, That is, the calculation unit 4 that calculates the rotation speed of the turbocharger 10 is mounted. For example, the calculation unit 4 counts the number of times that the electric signal is equal to or higher than a predetermined threshold voltage over a predetermined time, and calculates the rotational speed of the turbocharger 10 based on the number of times.

  In addition, although the case where the calculation part 4 was mounted in ECU was demonstrated here, the calculation part 4 may be provided separately from ECU, for example, the calculation part 4 is modularized and calculated by the calculation part 4. The rotation speed of the turbocharger 10 may be output to the ECU. The calculation unit 4 may be mounted on the sensor unit 3. Furthermore, electrical signals indicating the detection results of the first magnetic detection element 31A and the detection results of the second magnetic detection element 31B are respectively sent to the calculation unit 4 through signal lines, and the calculation unit 4 calculates the difference between the two detection results. It may be taken.

  The detection axis D1 of the first magnetic detection element 31A and the detection axis D2 of the second magnetic detection element 31B are indicated by arrows, respectively. The first and second magnetic detection elements 31A and 31B detect magnetic fields in the directions of the detection axes D1 and D2, and output a voltage signal corresponding to the magnetic field strength. The detection axes D1 and D2 are parallel to the radial direction of the compressor wheel 17 indicated by a one-dot chain line in FIG. The first and second magnetic detection elements 31A and 31B are arranged such that the detection axes D1 and D2 are on the same straight line.

  The rotation axis O of the compressor wheel 17 in the radial direction of the compressor wheel 17 and the magnetic field detection part (the center part of the first and second magnetic detection elements 31A and 31B) in the first and second magnetic detection elements 31A and 31B. If the distances are g1 and g2, respectively, g2 is longer than g1, g1 is, for example, 17.5 mm, g2 is, for example, 19.25 mm, and the difference Δg is 1.75 mm. May be made larger. That is, g2 is preferably 1.1 times or more than g1. Moreover, g2 is good to be 1.5 times or less of g1, so that the influence of external noise is not greatly different.

  Due to the difference in distance, the magnetic field detected by the second magnetic detection element 31B becomes smaller than the magnetic field detected by the first magnetic detection element 31A. Then, the turbo rotation sensor 1 measures the rotational speed of the compressor wheel 17 based on the difference between the detection results of the first and second magnetic detection elements 31A and 31B generated by the difference in the radial distance from the magnet 2. Is possible.

(Experimental result)
FIG. 6A is a schematic diagram showing the configuration of the turbo rotation sensor 1 according to the present embodiment. FIG. 6B is a schematic diagram illustrating the configuration of a turbo rotation sensor 1A according to a comparative example. As shown in FIGS. 6A and 6B, the first and second magnetic detection elements 31 </ b> A and 31 </ b> B are mounted on one substrate 30 in the sensor module 32. The detection axes D1 and D2 are parallel to the substrate 30. In the turbo rotation sensor 1 according to the present embodiment, the substrate 30 is disposed perpendicular to the direction parallel to the rotation axis O of the compressor wheel 17. Is done. In the turbo rotation sensor 1, the distance g1 between the rotation axis O and the first magnetic detection element 31A and the interval Δg between the first magnetic detection element 31A and the second magnetic detection element 31B are shown in FIG. The same dimensions as described above (g1 = 17.5 mm, Δg = 1.75 mm, h = 1.0 mm). The compressor housing 15 is made of aluminum.

  On the other hand, in the turbo rotation sensor 1 </ b> A according to the comparative example, the direction of the substrate 30 is perpendicular to the radial direction of the compressor wheel 17, and the detection axes D <b> 1 and D <b> 2 are parallel to the rotation axis O of the compressor wheel 17. The first and second magnetic detection elements 31A and 31B are arranged in parallel with the rotation axis O. In the turbo rotation sensor 1A, refer to FIG. 5 for the distance g1 between the rotation axis O and the first magnetic detection element 31A and the distance Δg between the first magnetic detection element 31A and the second magnetic detection element 31B. The same dimensions as described above (g1 = 17.5 mm, Δg = 1.75 mm, h = 1.0 mm). The compressor housing 15 is made of aluminum.

  FIG. 7A shows the detection results (magnetic flux densities) of the first and second magnetic detection elements 31A and 31B of the turbo rotation sensor 1 according to the present embodiment on the vertical axis, and the compressor wheel. It is a graph which shows the rotation angle from the reference position of 17 and the magnet 2 on a horizontal axis. In FIG. 7A, the difference between the magnetic field detection results of the first and second magnetic detection elements 31A and 31B is indicated by a broken line. FIG. 7B shows the detection results of the magnetic fields of the first and second magnetic detection elements 31A and 31B of the turbo rotation sensor 1A according to the comparative example and the difference between the vertical and horizontal axes common to FIG. It is a graph shown by an axis.

  As shown in FIG. 7A, the magnetic flux density detected by the second magnetic detection element 31B is greatly reduced with respect to the magnetic flux density detected by the first magnetic detection element 31A. The degree of reduction is greater than the degree of reduction assumed by the interval Δg between the first magnetic detection element 31A and the second magnetic detection element 31B. The reason why the magnetic flux density is greatly reduced in this way is considered to be due to eddy currents generated around the sensor hole 15a in the compressor housing 15 when the compressor wheel 17 and the magnet 2 rotate at high speed. As a result of verification by the present inventor, when the rotation speed of the compressor wheel 17 is 200,000 rpm, it is detected by the second magnetic detection element 31B at a larger rate than when the rotation speed is several thousand rpm. It has been confirmed that the magnetic flux density decreases with respect to the magnetic flux density detected by the first magnetic detection element 31A. FIGS. 7A and 7B show magnetic field detection results when the compressor wheel 17 rotates at 200,000 rpm.

  As shown in the graphs of FIGS. 7A and 7B, the difference between the detection results in the turbo rotation sensor 1 according to the present embodiment is the difference between the detection results in the turbo rotation sensor 1A according to the comparative example. The amplitude is larger than the difference. Therefore, the rotational speed of the compressor wheel 17 can be measured more accurately even under the influence of external noise.

(Operation and effect of the embodiment)
According to the embodiment of the present invention described above, the rotational speed of the compressor wheel 17 can be measured based on the difference between the detection results of the first and second magnetic detection elements 31A and 31B. Even if the sensitivity of the first and second magnetic detection elements 31A and 31B changes due to a temperature rise due to heat, the change is canceled out and the rotation speed of the compressor wheel 17 can be accurately measured. In addition, since the first and second magnetic detection elements 31A and 31B are arranged side by side in the radial direction of the compressor wheel 17, the external noise can also be detected by the first and second magnetic detection elements 31A and 31B. The influence on the measurement result is offset and the rotational speed of the compressor wheel 17 can be accurately measured.

  Further, as shown in FIG. 7A, a sufficient difference appears in these detection results due to the difference in distance between the rotation axis O of the compressor wheel 17 and the first and second magnetic detection elements 31A, 31B. By comparing this difference with a predetermined threshold voltage, the rotational speed of the compressor wheel 17 can be measured. Even when the interval between the first magnetic detection element 31A and the second magnetic detection element 31B is widened, it is not necessary to increase the diameter of the tip of the sensor unit 3 and the inner diameter of the sensor hole 15a, and the compressor housing 15 It is possible to suppress a decrease in strength.

  In addition, according to the present embodiment, since the tip of the sensor unit 3 including the first and second magnetic detection elements 31A and 31B is accommodated in the sensor hole 15a of the compressor housing 15, the first and second External noise reaching the magnetic detection elements 31 </ b> A and 31 </ b> B is suppressed by the compressor housing 15. Furthermore, by forming the sensor hole 15a for accommodating the sensor unit 3 so as not to penetrate the compressor housing 15, damage to the sensor unit 3 due to the wind pressure of the intake air can be suppressed, and reliability can be improved.

(Summary of embodiment)
Next, the technical idea grasped from the embodiment described above will be described with reference to the reference numerals in the embodiment. However, the reference numerals and the like in the following description are not intended to limit the constituent elements in the claims to the members and the like specifically shown in the embodiments.

[1] A turbine (12), which is provided in an exhaust passage (14) of an internal combustion engine of a vehicle and accommodates in a turbine housing (18) a turbine wheel (20) that is rotationally driven by exhaust from the internal combustion engine; A compressor (11) which is provided in an intake passage (13) of the internal combustion engine and is driven to rotate by the rotation of the turbine wheel (20) in a compressor housing (15). A turbo rotation sensor (1) mounted on the turbocharger (10) for detecting the rotational speed of the compressor wheel (17), wherein the turbo rotation sensor (1) rotates integrally with the compressor wheel (17), A magnet (2) having a magnetic pole, and the magnet (2) are attached to the compressor housing (15). A sensor unit (3) having first and second magnetic detection elements (31A, 31B) capable of detecting the radial magnetic field of the presser wheel (17), and the first and second magnetic detection elements ( 31A, 31B) are arranged side by side in the radial direction of the compressor wheel (17), and the first and second magnetic detections generated by the difference in distance (g1, g2) from the magnet (2) A turbo rotation sensor (1) capable of measuring a rotation speed of the compressor wheel (17) based on a difference between detection results of the elements (31A, 31B).

[2] The sensor section (3) is disposed in a housing hole (sensor hole 15a) formed in the compressor housing (15) along the radial direction of the compressor wheel (17), [1] The turbo rotation sensor (1) described in 1.

[3] The turbo according to [2], wherein the accommodation hole (sensor hole 15a) is a blind hole that opens to the outer surface of the compressor housing (15) and does not open to the inner surface of the compressor housing (15). Rotation sensor (1).

[4] A turbine (12), which is provided in an exhaust passage (14) of an internal combustion engine of a vehicle and accommodates in a turbine housing (18) a turbine wheel (20) that is rotationally driven by exhaust from the internal combustion engine; A compressor (11) that is provided in an intake passage (13) of the internal combustion engine and is driven to rotate by rotation of the turbine wheel (20) in a compressor housing (15); and the compressor A magnet (2) that rotates integrally with the wheel (17) and has a plurality of magnetic poles in the circumferential direction, and is attached to the compressor housing (15), and is arranged in the radial direction of the compressor wheel (17) by the magnet (2). A sensor unit (3) having first and second magnetic detection elements (31A, 31B) capable of detecting a magnetic field, The first and second magnetic detection elements (31A, 31B) are arranged side by side in the radial direction of the compressor wheel (17), and the first and second magnetic detection elements are generated due to a difference in distance from the magnet (2). A turbocharger (10) capable of measuring the rotational speed of the compressor wheel (17) based on a difference between detection results of the two magnetic detection elements (31A, 31B).

  While the embodiments of the present invention have been described above, the embodiments described above do not limit the invention according to the claims. In addition, it should be noted that not all the combinations of features described in the embodiments are essential to the means for solving the problems of the invention.

  Further, the present invention can be appropriately modified and implemented without departing from the spirit of the present invention. For example, in the above embodiment, the case where both the magnetic detection elements 31A and 31B are arranged so that the detection axes D1 and D2 of the first and second magnetic detection elements 31A and 31B are on the same straight line has been described. However, the first magnetic detection element 31 </ b> A and the second magnetic detection element 31 </ b> B may be slightly displaced in the sensor module 32 along the axial direction or the circumferential direction of the compressor wheel 17.

DESCRIPTION OF SYMBOLS 1 ... Turbo rotation sensor 3 ... Sensor part 31A ... 1st magnetic detection element 31B ... 2nd magnetic detection element 11 ... Compressor 12 ... Turbine 13 ... Intake passage 14 ... Exhaust passage 15 ... Compressor housing (housing)
15a ... Sensor hole 17 ... Compressor wheel 20 ... Turbine wheel

Claims (3)

A compressor in which a compressor wheel that is rotationally driven is housed in a compressor housing;
A magnet that rotates integrally with the compressor wheel and has a plurality of magnetic poles in the circumferential direction;
A sensor unit which is attached to the compressor housing and has first and second magnetic detection elements capable of detecting a radial magnetic field of the compressor wheel by the magnet,
The first and second magnetic detection elements are arranged side by side in the radial direction of the compressor wheel,
The rotational speed of the compressor wheel can be measured based on the difference between the detection results of the first and second magnetic detection elements generated by the difference in distance from the magnet.
Turbocharger. The sensor unit is disposed in a receiving hole formed in the compressor housing along a radial direction of the compressor wheel.
The turbocharger according to claim 1. The accommodation hole is a blind hole that opens on the outer surface of the compressor housing and does not open on the inner surface of the compressor housing.
The turbocharger according to claim 2.

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