JP2014230387A - Rotary electric machine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve detection accuracy in a configuration for detecting a rotating position of a rotor by detecting a leakage magnetic flux from a rotor magnet.SOLUTION: In a brushless motor 1, a Hall device 21 detects a leakage magnetic flux from a rotor magnet 4 and outputs a signal corresponding to a strength of the leakage magnetic flux and on the basis of the output signal, a rotating position of the rotor 2 is detected by a rotating position detection circuit. In a rotational axis direction of the rotor 2, a sensor pin 24 extending toward the Hall device 21 is disposed between the rotor magnet 4 and the Hall device 21, and a metal body which is disposed at a position different from the sensor pin 24 in the rotational axis direction, is disposed at a position adjacent with the Hall device 21.

Description

  The present invention relates to a rotating electrical machine, and more particularly, to a rotating electrical machine including a circuit that detects a magnetic flux leaking from each of a plurality of magnet pieces arranged along a rotating body to detect a rotational position of the rotating body.

  In a rotating electrical machine such as a motor, a configuration for detecting the rotational position of a rotor by detecting leakage magnetic flux from each of a plurality of magnet pieces arranged along a rotor which is a rotating body is already well known. In recent years, techniques for improving the detection accuracy of the rotational position of the rotor have been developed. For example, Patent Document 1 discloses a pin made of metal between a Hall element that detects leakage magnetic flux and a rotor magnet in a brushless motor. The structure provided with is described. According to such a configuration, the pin induces leakage magnetic flux from the rotor magnet to the Hall element, so that the Hall element detects the leakage magnetic flux satisfactorily, and as a result, the rotational position detection accuracy is improved.

JP 2010-98787 A

  On the other hand, in the configuration in which a member for guiding the leakage magnetic flux from the rotor magnet to the Hall element is provided as in Patent Document 1, the detection accuracy of the rotational position is further improved by facilitating the induction of the leakage magnetic flux to the Hall element. It is demanded.

  Further, when detecting the leakage magnetic flux from the rotor magnet, the leakage magnetic flux from the stator is superimposed on the leakage magnetic flux from the rotor magnet during the period when the coil provided in the stator is energized, and these leakage magnetic fluxes are synthesized. The combined magnetic flux may be detected by the Hall element. In such a case, even if an attempt is made to detect the rotational position of the rotor based on the leakage magnetic flux from the rotor magnet, the detection result deviates from the original position due to the influence of the leakage magnetic flux from the stator, resulting in the rotational position of the rotor. The detection accuracy with respect to is reduced.

Therefore, the present invention has been made in view of the above-described problems, and an object of the present invention is to detect the magnetic flux leakage from a plurality of magnet pieces arranged along the rotating body and detect the rotational position of the rotating body. It is providing the rotary electric machine which can improve the detection accuracy at the time.
Another object of the present invention is to provide a rotating electrical machine capable of appropriately detecting the rotational position of a rotating body even when the leakage flux from the stator is superimposed on the leakage flux from the rotor magnet. It is.

According to the rotating electrical machine of the present invention, the object is to detect a magnetic flux leakage from each of a plurality of magnet pieces arranged along the rotating body and output a signal corresponding to the strength of the magnetic flux leakage. A rotation position detection circuit that detects a rotation position of the rotating body based on an output signal from the magnetic flux detection element, and is disposed between the magnet piece of the rotating body and the magnetic flux detection element, A first magnetic body extending toward the magnetic flux detection element; a second magnetic body disposed at a position different from the first magnetic body; and disposed at a position adjacent to the magnetic flux detection element; It is solved by providing.
In the above rotating electric machine, the direction in which the magnetic flux leaked from the magnet piece passes after passing through the first magnetic body is regulated by the second magnetic body, and specifically, regulated to go to the second magnetic body. The And by arrange | positioning this 2nd magnetic body in the position adjacent to a magnetic flux detection element, the leakage magnetic flux which goes to a 2nd magnetic body comes to pass a magnetic flux detection element, and a magnetic flux detection element carries out leakage magnetic flux. It becomes easy to detect. As a result, the ability to detect leakage magnetic flux by the magnetic flux detection element is enhanced, so that the detection accuracy with respect to the rotational position of the rotating body can be improved.

In the above rotating electrical machine, the second magnetic body is a metal body in which a through hole is formed, and at least a part of the magnetic flux detection element is accommodated in the through hole. One magnetic body may be arranged at a position facing the opening of the through hole.
If it is the above structure, since at least one part of a magnetic flux detection element is accommodated in the through-hole formed in the metal body as a 2nd magnetic body, it becomes easier to guide a leakage magnetic flux in a magnetic flux detection element. As a result, the detection accuracy with respect to the rotational position of the rotating body can be further improved.

In the above rotating electric machine, the rotating electric machine may be a motor having an end plate, and the metal body may form the end plate.
If it is the above structure, since an end plate can be utilized as a 2nd magnetic body, it becomes possible to suppress the increase in a number of parts.

The rotating electrical machine may include a resin support that supports the first magnetic body, and the metal body may be embedded in the support.
If it is the above structure, since the metal body as a 2nd magnetic body is embedded in the support body, it will become possible to suppress the enlargement of the rotary electric machine accompanying installation of the said metal body.

The rotating electrical machine includes a circuit board on which the rotational position detection circuit is mounted, and the second magnetic body is a metal body provided in the circuit board, and is provided on a bottom surface of the magnetic flux detection element. It is good also as contacting.
If it is the above structure, since it becomes possible to provide a 2nd magnetic body using a circuit board, it becomes possible to suppress the enlargement of a rotary apparatus. Further, since the second magnetic body is in contact with the bottom surface of the magnetic flux detection element, the leakage magnetic flux can be more easily guided into the magnetic flux detection element, and the detection accuracy with respect to the rotational position of the rotating body can be further improved. It becomes.

In the rotating electrical machine, the second magnetic body may be a metal body incorporated in the rotational position detection circuit, and may be disposed at a position surrounding the magnetic flux detection element.
If it is the above structure, it will become possible to attain space saving of the arrangement space of a 2nd magnetic body by utilizing the metal body integrated in the rotation position detection circuit as a 2nd magnetic body.

Further, in the above rotating electric machine, the rotating electric machine includes a rotor as the rotating body, a stator disposed at a position facing the rotor, a plurality of slots formed in the stator, and windings between the slots. And the rotational position detection circuit detects the leakage magnetic flux detected by the magnetic flux detection element when the rotor is rotated in a state where the winding is not energized. The maximum value of the strength is stored, the signal corresponding to the strength of the leakage magnetic flux detected by the magnetic flux detection element when the rotor is rotated by energizing the winding, and the stored maximum The rotational position may be detected based on the value.
In the above configuration, the maximum value of the leakage magnetic flux detected by the magnetic flux detection element when the rotor is rotated when the winding is not energized is set as a reference value, and the reference value and the winding are energized. Then, the rotational position of the rotor is detected based on the strength of the leakage magnetic flux detected by the magnetic flux detection element when the rotor is rotated. In other words, if the strength of the leakage flux detected by the magnetic flux detection element when the rotor is rotated while the winding is not energized is used as the reference value, the leakage flux from the stator side is converted into the leakage flux from the rotor side. Even when the combined magnetic flux is detected, the rotational position is detected based on the leakage magnetic flux from the rotor side by detecting the rotational position of the rotor when the combined magnetic flux matches the reference value. You will get the same results. Thereby, even if the leakage magnetic flux from the stator is superimposed on the leakage magnetic flux from the magnet piece attached to the rotor, the rotational position of the rotor can be accurately detected.

According to the rotating electric machine of the present invention, the direction in which the leakage magnetic flux from the magnet piece passes after passing through the first magnetic body is regulated so as to go to the second magnetic body, and the second magnetic body is controlled by the magnetic flux detection element. The magnetic flux detecting element can easily detect the leakage magnetic flux. As a result, the ability to detect leakage magnetic flux by the magnetic flux detection element is enhanced, so that the detection accuracy with respect to the rotational position of the rotating body can be improved.
Further, according to the rotating electrical machine of the present invention, the maximum value of the strength of the leakage magnetic flux detected by the magnetic flux detection element when the rotor is rotated without energizing the winding is used as the reference value, The rotational position of the rotor is detected based on the strength of the leakage magnetic flux detected by the magnetic flux detecting element when the winding is energized to rotate the rotor. As a result, even if the leakage flux from the stator is superimposed on the leakage flux from the magnet piece attached to the rotor, the rotational position of the rotor can be detected with high accuracy.

It is a side view including a partial cross section of a rotating electrical machine. It is a top view containing the partial cross section of a rotary electric machine. It is a schematic diagram which shows the structure of the conventional rotational position detection mechanism. It is a figure when a 1st magnetic body and its periphery are seen from the rotating shaft direction one end side. It is a schematic diagram which shows the 1st structural example of a rotation position detection mechanism. It is a figure which shows the correlation with the positional relationship between the components of a rotation position detection mechanism, and the strength of leakage magnetic flux. It is a schematic diagram which shows the 2nd structural example of a rotation position detection mechanism. It is a schematic diagram which shows the 3rd structural example of a rotation position detection mechanism. It is a schematic diagram which shows the 4th structural example of a rotation position detection mechanism. It is a schematic diagram which shows the 5th structural example of a rotation position detection mechanism. It is explanatory drawing about the method of detecting the rotation position of a rotor, when the leakage magnetic flux from a stator side overlaps with the leakage magnetic flux from a rotor side.

Hereinafter, a rotating electrical machine according to an embodiment of the present invention (hereinafter referred to as the present embodiment) will be described with reference to the drawings.
First, the basic configuration of the rotating electrical machine according to the present embodiment will be described with reference to FIGS. 1 and 2. FIG. 1 is a side view of a rotating electrical machine according to the present embodiment, and FIG. 2 is a plan view of the rotating electrical machine according to the present embodiment. 1 and 2 both include a cross-sectional view in a part (the right half in the drawing), and are depicted somewhat simplified for easy understanding.

  The rotating electrical machine according to the present embodiment is a brushless motor, more specifically, an outer rotor type motor. As shown in FIG. 1, a brushless motor (hereinafter, this motor) 1 according to the present embodiment includes a motor body 10 including a rotor 2 and a stator 6, and a rotational position detection mechanism 20 that detects the rotational position of the rotor 2. . And in this motor 1, when the rotation position of the rotor 2 is detected, among the three-phase (U-phase, V-phase, W-phase) coils formed in the stator 6, the corresponding coil is energized.

  The configuration of the motor main body 10 is substantially the same as that of a known outer rotor type brushless motor, and the rotor 2 as a rotating body is rotatable and faces the rotor 2 in the radial direction of the rotor 2. The stator 6 is arranged at the position. Referring to FIGS. 1 and 2, the rotor 2 rotates at the center in the radial direction of the rotor 2, the bottomed cylindrical yoke 3, the plurality of rotor magnets 4 arranged along the inner surface of the yoke 3. It is comprised by the rotating shaft 5 arrange | positioned freely. Here, the plurality of rotor magnets 4 arranged along the inner surface of the yoke 3 correspond to magnet pieces constituting magnetic poles, and N poles and S poles are alternately arranged along the rotation direction of the rotor 2. And it arrange | positions at equal intervals.

  The number of poles of the rotor 2 is P (P is a natural number), and P = 6 in the configuration shown in FIG. In the present embodiment, each rotor magnet 4 has an arc shape and is attached to the inner surface of the yoke 3. However, the present invention is not limited to this, and each rotor magnet 4 may be embedded in the side wall of the yoke 3.

  The stator 6 is positioned on the inner side of the rotor magnet 4 in the radial direction of the rotor 2 and is arranged concentrically with the rotor 2. The stator core 7 as a constituent element of the stator 6 includes a plurality of teeth 7a protruding in a substantially T shape toward the radially outer side of the rotor 2, and a plurality of slots 7b formed between the teeth 7a. Winding M is wound around. Thereby, the stator 6 has a core having a three-phase (U-phase, V-phase, W-phase) coil. In this embodiment, when the number of slots 7b is S (S is a natural number), S is 1.5 times the number of poles P, and S = 9 in the configuration shown in FIG. .

  The stator 6 is fixed in a non-rotatable manner with respect to the end plate 8 disposed at a position that closes the opening of the yoke 3. The end plate 8 is configured by a disk-shaped member made of a metal body. Note that a through hole 8a is formed in the end plate 8 according to the present embodiment. The through hole 8a is formed between the rotor 2 (more specifically, the inner surface of the rotor magnet 4) and the stator 6 in the radial direction of the rotor 2, and one end in the longitudinal direction of a sensor pin 24 to be described later is formed in the opening. The department is facing.

  Next, the schematic configuration of the rotational position detection mechanism 20 will be described. The rotational position detection mechanism 20 includes a Hall element 21 as a magnetic flux detection element, a circuit board 22 on which a rotational position detection circuit including the Hall element 21 is mounted, As a major component. And said Hall element 21 detects the leakage magnetic flux from each of the rotor magnet 4 during rotation of the rotor 2, and outputs the signal according to the strength (specifically magnetic flux density) of the leakage magnetic flux. . The rotational position detection circuit detects the rotational position of the rotor 2 based on the output signal from the hall element 21.

  In the motor 1, as shown in FIG. 1, the Hall element 21 is disposed on the opposite side of the motor body 10 with the end plate 8 interposed in the axial direction of the rotating shaft 5 (that is, the rotating shaft direction). In this motor 1, the sensor pin 24 is provided between the rotor magnet 4 and the hall element 21 in the axial direction of the rotary shaft 5 in order to guide the leakage magnetic flux from the rotor magnet 4 to the hall element 21 under such a positional relationship. Has been placed. The sensor pin 24 corresponds to the first magnetic body in the present invention, and is a substantially rectangular parallelepiped metal body extending along the axial direction of the rotary shaft 5 toward the Hall element 21. The sensor pin 24 is a fixing member (non-fixed member) made of a resin material so that the end portion located on the Hall element 21 side in the longitudinal direction faces the opening of the through hole 8a formed in the end plate 8. It is fixed to the end plate 8 at (shown).

  By providing the sensor pin 24 as described above, the leakage magnetic flux from the rotor magnet 4 can be guided to the Hall element 21. On the other hand, in the configuration using the sensor pin 24, the leakage magnetic flux from the rotor magnet 4 may not be properly guided to the Hall element 21 after passing through the sensor pin 24. For example, as shown in FIG. 3, in the configuration in which the sensor pin 24 extends through the through hole 8 a of the end plate 8 to the position closest to the Hall element 21, a part of the leakage magnetic flux that passes through the sensor pin 24 is the Hall element 21. Instead, it may flow to the end plate 8. FIG. 3 is a schematic diagram showing a configuration of a conventional rotational position detection mechanism, and specifically shows a device arrangement around the sensor pin 24 in the conventional example. In the figure, the flow of leakage magnetic flux is indicated by a broken line.

  As described above, when the leakage magnetic flux from the rotor magnet 4 is not properly guided to the hall element 21, the detection accuracy with respect to the rotational position of the rotor 2 is lowered. Vibration noise is generated due to the shift.

  To solve the above problem, in order to keep the portion of the end plate 8 located around the sensor pin 24 as far as possible from the sensor pin 24 and suppress the leakage flux from flowing into the portion, as shown in FIG. It is conceivable to increase the diameter of 8a. However, in such a configuration, the strength of the end plate 8 is reduced as the diameter of the hole increases. FIG. 4 is a view of the sensor pin 24 and its periphery when viewed from one axial end side of the rotating shaft 5.

  As another countermeasure, from the viewpoint of securing the amount of leakage magnetic flux, the length of the rotor magnet 4 in the axial direction of the rotating shaft 5 (hereinafter referred to as magnet length) is made longer, for example, the magnet length is increased in the axial direction. It is conceivable to set the length longer than the length of the core (hereinafter referred to as the core length). However, if the magnet length is set longer than the core length, the amount of the magnet used is increased accordingly, and the motor manufacturing cost becomes higher.

On the other hand, in the rotational position detection mechanism 20 according to the present embodiment, the leakage magnetic flux from the rotor magnet 4 is appropriately guided from the sensor pin 24 to the hall element 21 while suppressing a decrease in strength of the end plate 8 and an increase in manufacturing cost. The structure which can do is adopted.
Hereinafter, the configuration of the rotational position detection mechanism 20 according to the present embodiment will be described in detail with reference to FIGS. FIG. 5 is a schematic diagram illustrating a configuration example of the rotational position detection mechanism 20 according to the present embodiment, and corresponds to FIG. 3. FIG. 6 is a graph showing the correlation between the positional relationship between the components of the rotational position detection mechanism 20 and the strength of the leakage magnetic flux.

  More specifically, the graph shown on the upper side in FIG. 6 shows the Hall element 21 by changing the positional relationship between the Hall element 21 and the metal body (the end plate 8 in FIG. 6) located around the Hall element 21. It shows a tendency when the detection accuracy changes, and the horizontal axis indicates the position of the Hall element 21 (strictly speaking, the bottom surface of the Hall element 21) with respect to the bottom surface position of the metal piece, and the vertical axis indicates The magnetic flux density of the leakage magnetic flux detected by the Hall element 21 when placed at each position, strictly speaking, when the leakage flux when the end plate 8 is provided with a relatively large diameter through hole 8a is used as a reference. The ratio (magnetic flux density ratio) is shown. On the other hand, the lower side of FIG. 6 schematically shows the positional relationship among the sensor pin 24, the Hall element 21 and the metal body at the time corresponding to the plots A to E in the graph shown in FIG.

  In the present embodiment, as shown in FIG. 5, the sensor pin 24 is arranged on the core side with respect to the through hole 8 a formed in the end plate 8 in the axial direction of the rotating shaft 5. That is, unlike the conventional example shown in FIG. 3, the sensor pin 24 according to the present embodiment does not pass through the through hole 8a. On the other hand, in the present embodiment, as shown in FIG. 5, a part of the Hall element 21 is accommodated in a through hole 8 a formed in the end plate 8. That is, the Hall element 21 according to the present embodiment has a part of the outer surface thereof wrapped with the end plate 8 in the axial direction of the rotating shaft 5, and specifically, adjacent to the outer edge portion of the through hole 8 a.

  Here, the end plate 8 is a metal body as described above, and functions as the second magnetic body of the present invention. That is, in the present embodiment, the metal body constituting the end plate 8 is disposed at a position different from the sensor pin 24 in the axial direction of the rotating shaft 5 and is disposed at a position adjacent to the Hall element 21. With such an arrangement, the leakage magnetic flux from the rotor magnet 4 is appropriately guided to the Hall element 21 without flowing into the end plate 8 after passing through the sensor pin 24.

  The effects described above will be described with reference to FIG. 6. The Hall element 21 is moved in the axial direction of the rotary shaft 5 with respect to the end plate 8 that is a metal body while maintaining the distance between the Hall element 21 and the sensor pin 24. At this time, the Hall element 21 wraps with the end plate 8 in a predetermined section of the movement range. Thus, in the section where the Hall element 21 wraps with the end plate 8, the magnetic flux density of the leakage magnetic flux detected by the Hall element 21 is relatively high as shown in FIG. This is because, when the hall element 21 is arranged at a position where it overlaps the end plate 8 in the axial direction of the rotating shaft 5, the direction in which the leakage magnetic flux from the rotor magnet 4 passes after passing through the sensor pin 24 is the end as a metal body. This is because the leakage magnetic flux directed to the end plate 8 passes through the Hall element 21 while being restricted to the plate 8.

As a result, the Hall element 21 can easily detect the leakage magnetic flux. As a result, the detection capability of the leakage magnetic flux by the Hall element 21 is increased, and thus the accuracy in detecting the rotational position of the rotor 2 can be improved. .
Further, since the detection accuracy of the leakage magnetic flux is improved by adjusting the positional relationship between the Hall element 21, the sensor pin 24, and the end plate 8 in the axial direction of the rotary shaft 5, the end plate 8 is relatively large as in the conventional example. It is not necessary to provide the through-hole 8a having a diameter and move the end plate 8 away from the sensor pin 24 as much as possible, and the diameter of the through-hole 8a can be minimized. For example, when the sensor pin 24 having a cross-sectional shape of 3.0 mm × 1.2 mm is used, a through hole 8 a having an outer diameter of about 5.0 mm may be provided. As a result, it is possible to suppress a decrease in the strength of the end plate 8 due to the drilling of the through hole 8a.

  As shown in FIG. 6, when the wrap amount between the Hall element 21 and the end plate 8 in the axial direction of the rotary shaft 5 becomes 1/3 of the thickness of the Hall element 21 (in FIG. The strength of the leakage magnetic flux detected by the Hall element 21 is comparable to the strength when the end plate 8 is provided with a relatively large through-hole 8a in the conventional example. Therefore, it is desirable to set the position of the Hall element 21 in the axial direction of the rotating shaft 5 so that the wrap amount is 1/3 or more of the thickness of the Hall element 21.

  Furthermore, in this embodiment, it is not necessary to make the magnet length longer than the core length in order to improve the detection accuracy of the leakage magnetic flux, and even if the magnet length is set to be relatively short, the amount of leakage magnetic flux guided to the Hall element 21 Is sufficiently secured. As a result, it becomes possible to reduce the motor manufacturing cost by reducing the amount of magnets used.

Furthermore, in the present embodiment, the sensor pin 24 is disposed at a position facing the opening of the through hole 8a of the end plate 8, and at least a part of the hall element 21 is accommodated in the through hole 8a. As a result, the leakage magnetic flux from the rotor magnet 4 can be more easily guided into the Hall element 21, and the detection accuracy of the rotational position of the rotor 2 can be further improved.
As described above, in the present motor 1, the detection accuracy of the rotational position of the rotor 2 is improved. As a result, it is possible to suppress the deviation of the timing of energizing the coils of the stator 6 and the generation of vibration noise caused by the deviation. .

  By the way, in the configuration of the rotational position detection mechanism 20 described above (hereinafter, the first configuration example), the metal body forming the end plate 8 constitutes the second magnetic body. As described above, in the first configuration example, it is possible to suppress the increase in the number of parts by using the end plate 8 as the second magnetic body. However, the present invention is not limited to the first configuration example, and as shown in FIG. 7, a metal body installed on the circuit board 22, for example, a configuration in which the circuit protection case 23 forms the second magnetic body (hereinafter referred to as “the second magnetic body”). Second configuration example). FIG. 7 is a schematic diagram illustrating the rotational position detection mechanism 120 according to the second configuration example, and corresponds to FIG.

  In the rotational position detection mechanism 120 shown in FIG. 7, a through hole 23a is formed in the circuit protection case 23, and the entire hall element 21 is accommodated in the through hole 23a, and the sensor pin 24 is connected to the through hole 23a. It is arranged at a position facing the opening. With such a positional relationship, in the second configuration example, it is possible to improve the same effect as in the first configuration example, that is, the detection accuracy of the rotational position of the rotor 2.

  In the first configuration example and the second configuration example, the end plate 8 and the circuit protection case 23 as members surrounding the hall element 21 are made of a metal body. However, the present invention is not limited to this. For example, as shown in FIG. 8, the end plate 128 may be configured by a resin material (hereinafter, a third configuration example). FIG. 8 is a schematic diagram showing a rotational position detection mechanism 220 according to the third configuration example, and corresponds to FIG.

In the third configuration example, a part of the resin end plate 128 is raised, and the sensor pin 24 is held on the raised portion. That is, the end plate 128 according to the third configuration example functions as a resin support that supports the sensor pin 24. In addition, a recess is formed on the back side (the side facing the circuit board 22) of the raised portion. The hall element 21 is accommodated in the recess as shown in FIG.
On the other hand, the end plate 128 according to the third configuration example includes an annular metal body 31 embedded in a portion surrounding the recess. In other words, the end plate 128 according to the third configuration example is an insert-molded product, and is manufactured by putting a resin material in a state where the annular metal body 31 is set in a mold. And in the 3rd structural example, the cyclic | annular metal body 31 comprises the 2nd magnetic body, and the through-hole 31a is formed in the center position of the said metal body 31. FIG.

In the third configuration example, a part of the hall element 21 is accommodated in the through hole 31 a and is wrapped with the annular metal body 31 in the axial direction of the rotating shaft 5. Thereby, also in the third configuration example, the leakage magnetic flux from the rotor magnet 4 can be appropriately guided from the sensor pin 24 to the hall element 21, thereby improving the detection accuracy with respect to the rotational position of the rotor 2.
As shown in FIG. 8, a part of the resin material constituting the end plate 128 is formed in the space between the annular metal body 31 and the Hall element 21 or in the space between the sensor pin 24 and the Hall element 21. It is good also as a resin layer being formed around.

  As described above, in the third configuration example, since the annular metal body 31 constituting the second magnetic body is embedded in the resin end plate 128, it is necessary to separately secure an installation space for the metal body 31. Therefore, it is possible to suppress an increase in motor size. In the third configuration example, as shown in FIG. 8, the annular metal body 31 is embedded so as to appear on the surface of the end plate 128 (the surface on the motor body 10 side), but as shown in FIG. A configuration in which the annular metal body 31 is completely embedded in the end plate 128 so as not to be exposed (hereinafter, a fourth configuration example) may be employed. Although the fourth configuration example is different from the third configuration example in this respect, both configuration examples are common in other points. FIG. 9 is a schematic diagram showing the rotational position detection mechanism 320 according to the fourth configuration example, and corresponds to FIG.

  In the first configuration example to the fourth configuration example, a member (the end plate 8, the circuit protection case 23, and the annular metal body 31) in which the hall element 21 forms the second magnetic body in the axial direction of the rotating shaft 5 is wrapped. It was decided that it was arranged in the position to do. However, the present invention is not limited to this, and as shown in FIG. 10, the metal body 32 constituting the second magnetic body is in contact with the bottom surface of the Hall element 21 (hereinafter referred to as a fifth configuration example). May be. FIG. 10 is a schematic diagram showing a rotational position detection mechanism 420 according to the fifth configuration example, and corresponds to FIG.

  In the fifth configuration example, the metal body 32 constituting the second magnetic body is provided in the circuit board 22 and is in contact with the bottom surface of the Hall element 21 as described above. That is, in the fifth configuration example, the Hall elements 21 are arranged in series with the metal bodies 32 in the axial direction of the rotating shaft 5. As described above, in the fifth configuration example, the second magnetic body can be provided by using the circuit board 22, so that the increase in the motor size can be suppressed. Further, since the second magnetic body is in contact with the bottom surface of the Hall element 21, the leakage magnetic flux from the rotor magnet 4 can be more easily guided into the Hall element 21, so that the detection accuracy with respect to the rotational position of the rotor 2 is further improved. This can be further improved. Note that, in the fifth configuration example, configurations other than the above points are the same as the third configuration example and the fourth configuration example, and thus description thereof is omitted.

  Further, in the configuration in which the metal body is incorporated in the rotational position detection circuit mounted on the circuit board 22, the metal body and the Hall element 21 have the rotation axis as in the first to fourth configuration examples. It is good also as wrapping in 5 axial directions. In other words, the metal body incorporated in the rotational position detection circuit may form the second magnetic body, and the metal body may be disposed at a position surrounding the Hall element 21. Even with such a configuration, it is possible to appropriately guide the leakage magnetic flux from the rotor magnet 4 from the sensor pin 24 to the hall element 21, thereby improving the detection accuracy with respect to the rotational position of the rotor 2.

  By the way, if the Hall element 21 tries to detect the leakage magnetic flux from the rotor magnet 4 while the coil provided in the stator 6 is energized, the leakage magnetic flux from the stator 6 is superimposed on the leakage magnetic flux from the rotor magnet 4. The Hall element 21 may detect a combined magnetic flux obtained by synthesizing these leakage magnetic fluxes. Thus, the synthetic | combination magnetic flux will be detected by the Hall element 21, and the rotational position of the rotor 2 will no longer be detected correctly. For this reason, in the present motor 1, the rotational position of the rotor 2 is detected on the assumption that the leakage magnetic flux from the stator 6 is superimposed on the leakage magnetic flux from the rotor 2. Hereinafter, this will be described in detail with reference to FIG.

  FIG. 11 is an explanatory diagram of a method for detecting the rotational position of the rotor 2 when the leakage magnetic flux from the stator 6 side is superimposed on the leakage magnetic flux from the rotor 2 side. More specifically, the upper diagram in FIG. 11 shows a graph showing the relationship between the rotational position of the rotor 2 and the leakage magnetic flux, with the horizontal axis representing the rotation angle (mechanical angle) and the vertical axis representing the magnetic flux. Each represents strength. Further, in the figure, a graph about the leakage magnetic flux from the rotor 2 side is shown by a thin solid line, a graph about the leakage magnetic flux from the stator 6 side is shown by a broken line, and a graph about the combined magnetic flux is shown by a thick solid line. ing.

  In FIG. 11, the middle diagram shows a waveform of a signal output when the Hall element 21 according to the conventional example detects a leakage magnetic flux, and the lower diagram relates to the conventional example mounted on the motor 1. It is the figure which showed the waveform of the signal output when Hall element 21 detects a leakage magnetic flux. In any of the drawings, the horizontal axis indicates the rotation angle (mechanical angle) and corresponds to the upper diagram in FIG. Moreover, in each figure, the signal waveform when only the leakage magnetic flux from the rotor 2 side is detected is indicated by a solid line, and the signal waveform when a combined magnetic flux is detected is indicated by a broken line.

  The trouble caused by the Hall element 21 detecting the combined magnetic flux will be described again. In the conventional example, the rotational position of the rotor 2 is usually detected at a point where the direction of the leakage magnetic flux changes. On the other hand, as shown in the upper and middle diagrams of FIG. 11, a point where the direction of the leakage flux changes between when the leakage flux from the rotor 2 only is detected and when the combined flux is detected, that is, the rotational position detection. The point will be different. That is, in the conventional configuration in which the rotational position of the rotor 2 is detected at a point where the direction of the leakage magnetic flux changes, the Hall element 21 detects the rotational position based on the composite magnetic flux when the coil is energized. A position deviated from the original rotational position detected based only on the leakage magnetic flux will be detected.

  As measures against the above problems, it is conceivable to arrange the Hall element 21 and the sensor pin 24 at a position where the leakage magnetic flux from the stator 6 side does not overlap when the direction of the leakage magnetic flux from the rotor 2 side changes. Depending on the relationship between the number of poles of the motor and the number of slots, there may be a case where there is no position where the leakage magnetic flux from the stator 6 side does not overlap. In such a case, if the rotational position of the rotor 2 is detected at a point where the direction of the leakage magnetic flux changes, the rotational position of the rotor 2 cannot be detected correctly due to the above-described problem, and the detection accuracy of the rotational position decreases. Will end up.

  On the other hand, in this motor 1, the rotational position of the rotor 2 is detected based on the strength of the magnetic flux detected by the Hall element 21 when the strength of the magnetic flux leakage from the stator 6 side becomes zero. . Describing such a detection method, the rotational position detection circuit provided in the motor 1 has a memory element (not shown), and the coil (in other words, the winding M) is not energized in the memory element. The maximum value (hereinafter referred to as numerical value α) of the strength of the leakage magnetic flux detected by the Hall element 21 when the rotor 2 is rotated is stored. On the other hand, the combined magnetic flux detected by the Hall element 21 when the rotor 2 is rotated while the coil is energized exhibits a behavior as shown in the upper diagram of FIG. 11, but as shown in FIG. The strength of the combined magnetic flux (hereinafter referred to as the numerical value β) when the strength of the leakage magnetic flux from the 6 side becomes 0 is almost equal to the maximum value of the leakage magnetic flux strength from the rotor 2 side, that is, the numerical value α. Will be equal. Here, the relationship that the numerical value α is substantially equal to the numerical value β is universal in a brushless motor, and is established regardless of the motor structure (for example, the number of poles and the number of slots of the motor).

  The rotational position detection circuit detects the rotational position of the rotor 2 based on the numerical value α and a signal corresponding to the strength of the combined magnetic flux detected by the Hall element 21 when the rotor 2 is rotated by energizing the coil. To do. More specifically, when the strength of the composite magnetic flux detected by the Hall element 21 becomes a numerical value α, the strength of the composite magnetic flux when the leakage magnetic flux from the stator 6 side is superimposed on the leakage magnetic flux from the rotor 2 side. However, it becomes substantially equal to the strength of only the leakage magnetic flux from the rotor side where the leakage magnetic flux from the stator 6 side is not superimposed. Considering this, the rotational position detection circuit of the motor 1 detects the rotational position of the rotor 2 with the numerical value α as a reference.

  More specifically, as shown in the lower diagram of FIG. 11, the Hall element 21 has a leakage flux intensity of 0 from the stator 6 side when the detected strength of the combined magnetic flux becomes a value α. A signal is output at that point. Then, when receiving the signal, the rotational position detection circuit determines that the rotational position of the rotor 2 has reached the magnetic center. That is, in this motor 1, even if the Hall element 21 detects the combined magnetic flux, the rotational position is detected based on the combined magnetic flux when the strength of the leakage magnetic flux from the stator 6 side becomes zero. The rotational position detected at such time is substantially equal to the rotational position detected based on only the leakage magnetic flux from the rotor 2 side at the same point.

  As described above, in the present motor 1, the rotational position of the rotor 2 is detected based on the strength of the magnetic flux detected by the Hall element 21 when the strength of the leakage magnetic flux from the stator 6 side becomes zero. Even if the leakage magnetic flux from the stator 6 side is superimposed on the leakage magnetic flux from the second side, the rotational position of the rotor 2 can be accurately detected. Further, since the strength of the magnetic flux detected by the Hall element 21 when the strength of the leakage magnetic flux from the stator 6 side becomes zero, the sensor pin 24 is arranged at a position where the leakage magnetic flux from the stator 6 side does not overlap. There is no need to let them. That is, the arrangement position of the sensor pin 24 can be freely set without being limited by the number of poles or the number of slots of the motor.

  Further, the rotational position of the rotor 2 when the strength of the leakage magnetic flux from the stator 6 side becomes 0 has a property of changing depending on the energization timing to the coil. If the strength of the leakage magnetic flux at the time of detecting the rotational position of the rotor 2 is appropriately set by utilizing such a property, it is possible to energize the coil at a target timing.

  The configuration of the rotating electric machine according to the embodiment of the present invention, specifically, the outer rotor type brushless motor, has been described above. However, the above embodiment is for facilitating the understanding of the present invention. The present invention is not limited to this. The present invention can be changed and improved without departing from the gist thereof, and the present invention includes the equivalents thereof.

  In the above-described embodiment, the configuration in which the rotating rotor 2 and the stator 6 are arranged at positions facing each other in the radial direction of the rotor 2 has been described as an example. However, the present invention is not limited to this. That is, the present invention is also applicable to a so-called axial gap type motor in which the rotor and the stator are disposed at positions facing each other in the direction of the rotor rotation axis (axial direction). In other words, the present invention is also applied to the case where the rotational position of the rotor is detected by detecting leakage magnetic flux in a motor in which a plurality of rotor magnets are arranged in the axial direction.

1 motor (rotary electric machine)
2 Rotor (Rotating body)
3 Yoke 4 Rotor magnet (magnet piece)
5 Rotating shaft 6 Stator 7 Stator core 7a Teeth 7b Slot 8 End plate (second magnetic body)
8a Through hole 10 Motor body 20, 120, 220, 320, 420 Rotation position detection mechanism 21 Hall element (magnetic flux detection element)
22 Circuit board 23 Circuit protection case (second magnetic body)
23a Through hole 24 Sensor pin (first magnetic body)
31, 32 Metal body (second magnetic body)
31a Through hole 128 End plate M Winding

Claims (7)

A magnetic flux detecting element that detects a magnetic flux leakage from each of a plurality of magnet pieces arranged along the rotating body and outputs a signal corresponding to the strength of the magnetic flux leakage, and outputs an output signal from the magnetic flux detecting element. A rotational position detection circuit for detecting a rotational position of the rotating body based on the
A first magnetic body disposed between the magnet piece of the rotating body and the magnetic flux detection element, and extending toward the magnetic flux detection element;
A rotating electrical machine comprising: a second magnetic body disposed at a position different from the first magnetic body and disposed at a position adjacent to the magnetic flux detection element. The second magnetic body is a metal body in which a through hole is formed,
At least a part of the magnetic flux detection element is accommodated in the through hole,
The rotating electrical machine according to claim 1, wherein the first magnetic body is disposed at a position facing the opening of the through hole. The rotating electrical machine is a motor having an end plate,
The rotating electrical machine according to claim 2, wherein the metal body forms the end plate. A resin support for supporting the first magnetic body;
The rotating electrical machine according to claim 2, wherein the metal body is embedded in the support body. A circuit board on which the rotational position detection circuit is mounted;
2. The rotating electrical machine according to claim 1, wherein the second magnetic body is a metal body provided in the circuit board and is in contact with a bottom surface of the magnetic flux detection element.   2. The rotating electrical machine according to claim 1, wherein the second magnetic body is a metal body incorporated in the rotational position detection circuit, and is disposed at a position surrounding the magnetic flux detection element. The rotating electrical machine includes a rotor as the rotating body, a stator disposed at a position facing the rotor, a plurality of slots formed in the stator, and a winding wound between the slots. A motor with
The rotational position detection circuit stores a maximum value of the strength of the leakage magnetic flux detected by the magnetic flux detection element when the rotor is rotated in a state where the winding is not energized, and the winding The rotation position is detected based on the signal corresponding to the strength of the leakage magnetic flux detected by the magnetic flux detection element when the rotor is rotated by energizing the rotor and the stored maximum value. The rotating electrical machine according to any one of claims 1 to 6.

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