JPH04299045A - Motor-driven air blower - Google Patents

Abstract

PURPOSE:To surely prevent the thermal destruction and malfunction of a detecting sensor by housing a temperature sensor which detects the ambient temperature of the detecting sensor in the second chamber having a sealed structure. CONSTITUTION:A temperature sensor 52 for detecting the ambient temperature of a detecting sensor 51 is fitted to the lower surface of a circuit board 50 adjacent to the sensor 51 in the second chamber 32. When the ambient temperature of the sensor 51 exceeds the guaranteed temperature of the sensor 51, the sensor 53 sends a signal indicating abnormality to a control circuit 54 for controlling a motor drive circuit 52. Upon receiving the signal, the circuit 54 outputs a control signal for stopping or reducing the rotation of a brushless motor 10 to the circuit 52. Therefore, the thermal destruction and malfunction of the detecting sensor 53 can be surely prevented.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electric blower used as a suction fan for a vacuum cleaner or a ventilation fan for a heating device.

0002

2. Description of the Related Art This type of electric blower is equipped with an inner rotor type brushless motor for rotationally driving a blower fan. Since this brushless motor uses a permanent magnet in the rotor, it is necessary to detect the rotational position of the rotor, energize a predetermined stator winding, and switch the phase. For this reason, in conventional brushless motors, multiple magnetic poles are magnetized at predetermined angles on a rotating disk that rotates together with the rotor, and a detection sensor using a Hall element is installed at a position facing the rotating disk. The rotational position of the rotor is determined by directly magnetically detecting the switching of the magnetic poles of the rotating disk using this detection sensor.

By the way, a brushless motor for an electric blower has a high driving voltage of 100 to 200 V, and a strong magnetic field is generated in the stator, so the stator generates a large amount of heat, and the stator coil temperature reaches 160 to 180 degrees Celsius. Temperatures may rise to as high as °C. From this, when using a Hall element as a detection sensor to detect the rotational position of the rotor, the guaranteed temperature at which this Hall element operates correctly is:
Since the temperature is generally about 100°C, it is necessary to provide the Hall element as far away from the stator as possible to suppress the influence of heat from the stator as much as possible.

However, even if the Hall element is moved away from the stator, there are various restrictions on the placement position of the Hall element due to the size of the motor, etc., so it is difficult to suppress the temperature rise of the Hall element. Of course, there are limits. For this reason, brushless motors have conventionally been known in which a temperature sensor for detecting the temperature around the stator is provided on the outer peripheral surface of a case that houses the stator. In this conventional brushless motor, when the temperature around the stator becomes abnormally high, the motor drive circuit is controlled by the output from the temperature sensor, and the rotation of the rotor is stopped or decelerated, thereby preventing the Hall element from overheating. I'm suppressing it.

[0005]

However, since the blower fan driven by the brushless motor is placed outside the case, there is a flow path for the air blown by the blower fan outside the case. exist. Then, since the above-mentioned temperature sensor is located in this air flow path, this temperature sensor is cooled by the air flowing through the above-mentioned flow path, and the temperature around the stator detected by the temperature sensor differs from the actual temperature. There will be a fairly large difference between the temperature inside the case and the temperature inside the case.

For this reason, the temperature around the stator cannot be detected accurately, and the ambient temperature of the detection sensor may exceed the guaranteed temperature, resulting in thermal damage to the detection sensor or failure of the motor due to error movement of the detection sensor. The rotation may become unstable.

The present invention has been developed based on the above circumstances, and is capable of accurately detecting the ambient temperature of a detection sensor, reliably preventing thermal damage and erroneous movement of the detection sensor, and reducing the number of air blowers. The purpose is to provide an electric blower with stable fan rotation.

[0008]

[Means for Solving the Problems] Accordingly, the present invention includes a brushless motor including a stator housed in a case and a rotor inserted inside the stator, and one end of the rotor shaft of the rotor. is led out of the case, and a blower fan that rotates integrally with the rotor is provided at one end of the rotor shaft, and the flow path of the air blown by the blower fan is located outside the case. In the electric blower, the inside of the case of the motor is divided into two chambers: a first chamber that houses the stator, and a second chamber that has a sealed structure and is separated from the first chamber and the air flow path. The other end of the rotor shaft is introduced into the second chamber, and a rotary disk for rotor position detection that rotates together with the rotor is installed at the other end of the rotor shaft introduced into the second chamber. The second chamber is provided with a detection sensor for detecting the rotational position of the rotor from the rotary disk, facing the rotary disk, and a detection sensor for detecting the ambient temperature of the detection sensor. The present invention is characterized in that a temperature sensor is provided that outputs a control signal to a control circuit that controls the drive circuit of the motor when the temperature exceeds a permissible limit.

[0009]

[Operation] According to this configuration, the detection sensor for detecting the rotational position of the rotor is housed in the second chamber of the case, and this second chamber is separated from the first chamber that houses the stator. Therefore, the thermal influence from the stator side on the detection sensor is reduced. Moreover, in this second chamber with a sealed structure,
Since the temperature sensor that detects the ambient temperature of the detection sensor is housed, the temperature sensor is not directly exposed to the air flow sent by the blower fan, eliminating the temperature difference between the temperature sensor installation area and the detection sensor installation area. be able to. In addition, since the detection sensor and the temperature sensor are housed in the same sealed space, changes in the ambient temperature of the detection sensor can be sensitively detected, and the responsiveness of the temperature sensor to temperature changes is significantly improved. Therefore, the ambient temperature of the detection sensor can be detected with high accuracy, and thermal damage and malfunction of the detection sensor can be reliably prevented.

0010

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be explained below based on an embodiment shown in the drawings.

In FIG. 4, an electric blower indicated by reference numeral 1 is housed in a blower box 2. As shown in FIG. The inside of the blower box 2 is partitioned by a partition wall 3 into a suction passage 4 having an inlet 4a and a discharge passage 5 having an outlet 5a. and,
A communication port 6 that communicates both the passages 4 and 5 is opened in the partition wall 3, and the electric blower 1 is supported at the opening of the communication port 6.

As shown in FIG. 1, the electric blower 1 has the following features:
It is equipped with an inner rotor type brushless motor 10. The brushless motor 10 projects into the discharge passage 5 of the blow box 2. A cylindrical case 11 constituting the outer shell of this brushless motor 10 is divided into an upper case 12 and a lower case 13.
are connected by screws 14. A stator 15 is housed inside the case 11. The stator 15 includes a stator core 16 and a winding 17 wound around the stator core 16. The winding 17 is electrically arranged with a phase difference of 120 degrees, for example, a phase difference of 100 degrees.
It is wound so that it can be driven in three phases with a driving voltage of V to 200V.

A rotor 19 is inserted into the stator 15 . The rotor 19 includes a rotor shaft 20 and a rotor magnet 2 provided on the outer periphery of the rotor shaft 20.
It consists of 1. The rotor magnet 21 is located inside the stator core 16, and a plurality of magnetic poles are magnetized at predetermined angles on the outer periphery facing the stator core 16. The upper end of the rotor shaft 20 passes through the upper wall 12a of the upper case 12 and is led out of the case 11.
A ball bearing 22 is provided to rotatably support the upper end of the 0.

A boss portion 23 is provided at the bottom of the lower case 13 to project downward. A fitting hole 24 is formed in the boss portion 23 . The fitting hole 24 is coaxial with the case 11, and a flange portion 25 projecting radially inward is integrally formed at the open end of the fitting hole 24. A downwardly extending cylindrical portion 26 is coaxially protruded from the outer peripheral portion of the lower end of the boss portion 23, and these cylindrical portions 26 and the boss portion 2
3 is integrated with the lower case 13.

A bearing holder 28 is fitted into the fitting hole 24 of the boss portion 23 . A through hole 29 is formed in the center of the bearing holder 28, through which the lower end of the rotor shaft 20 passes.
A ball bearing 30 is provided to rotatably support the lower end of the 0. Therefore, the rotor shaft 20 of the rotor 19 is supported at its upper and lower ends by the frame 11 via ball bearings 22 and 30, so that the rotor magnet 21 is coaxially located inside the stator core 16. .

The upper and lower ball bearings 22 and 30 that support the rotor shaft 20 are sealed bearings filled with grease.

The bearing holder 28 and ball bearing 30 are
The interior of the case 11 is divided into two chambers: a first chamber 31 that accommodates the stator 15 and the rotor magnet 21, and a second chamber 32 that is separated from the first chamber 31. second chamber 3
2 is located inside the boss portion 23 and the cylindrical portion 26, and the open end of the cylindrical portion 32 is closed by a shield plate 33. The shield plate 33 serves as a bottom plate of the second chamber 32, and seals the second chamber 32 without opening it to the discharge passage 5.

The lower end of the rotor shaft 20 passes through a ball bearing 30 and is introduced into the second chamber 32. A bracket 35 that also serves as a back yoke is coaxially fitted to the outer periphery of the lower end of the rotor shaft 20.
A rotary disk 36 for detecting the rotor position is coaxially superimposed on the lower surface of the rotor 5 . This rotary disk 36 is fastened and fixed to the lower end surface of the rotor shaft 20 via screws 37 so as to rotate together with the rotor shaft 20. The rotary disk 36 has a plurality of magnetic poles alternately magnetized at predetermined angles, and in this embodiment, since three-phase drive is used, eight magnetic poles are magnetized. This rotary disk 36 and bracket 3
5 is located inside the fitting hole 24, and a thrust spring 38 made of a wave washer or the like is inserted between the flange portion 25 of the fitting hole 24 and the bearing holder 28. . The thrust spring 38 presses the bearing holder 28 toward the first chamber 31, and this pressing absorbs play between the upper and lower ball bearings 22, 30.

Furthermore, a rotor shaft 20 passing through the case 11
A centrifugal blower fan 40 is fastened and fixed to the upper end of the fan 40 via a nut 41. The area around this blower fan 40 is covered by a fan cover 42. The fan cover 42 has an open bottom surface, and this opening portion is fitted onto the outer periphery of a flange-shaped support wall 43 protruding from the outer circumferential surface of the upper case 12 . A suction port 44 connected to the communication port 6 of the blower box 2 is opened at the center of the upper surface of the fan cover 42 . The suction port 44 faces the rotation center of the blower fan 40, and when the blower fan 40 rotates, the air sucked in from the suction port 44 is discharged from the outer periphery of the blower fan 40 into the fan cover 42. Ru. An air discharge port 45 is opened in the support wall 43 that supports the fan cover 42, and the air discharged into the fan cover 42 is passed through the discharge passage located outside the case 11 through the discharge port 45. Air is blown within 5.

By the way, the second chamber 32 of the case 11
A circuit board 50 is housed in the housing. The circuit board 50 is fastened and fixed to the lower surface of the boss portion 23 of the lower case 13 via screws 49, and its center portion is attached to the rotary disk 3.
It is close to the bottom surface of 6. On the lower surface of the circuit board 50, a rotor magnet 2 is located at a portion facing the rotary disk 36.
Detection sensor 51 for magnetically detecting the rotational position of 1
is provided. The detection sensor 51 uses, for example, a Hall element. Since the motor 10 of this embodiment is three-phase driven, three detection sensors 51 are used, and as shown in FIG.
They are arranged with a phase difference of 20°. therefore,
This detection sensor 51 detects switching of the magnetic poles of the rotary disk 36 and determines the rotational position of the rotor magnet 21.
A signal indicating the rotational position of the rotor magnet 21 is sent to the motor drive circuit 52.

Furthermore, a temperature sensor 53 made of a thermal fuse or the like is attached to the bottom surface of the circuit board 50. The temperature sensor 53 is for detecting the ambient temperature of the detection sensor 51, and in the second chamber 32,
It is provided at a position adjacent to the detection sensor 51. The temperature sensor 53 activates the motor drive circuit 52 when the ambient temperature of the detection sensor 51 exceeds the guaranteed temperature of the detection sensor 51.
A signal indicating an abnormality is sent to a control circuit 54 for controlling the brushless motor 10. When this control circuit 54 receives a signal from the temperature sensor 53, it sends a control signal to stop or decelerate the rotation of the brushless motor 10. The motor drive circuit 5
Output to 2.

In the case of this embodiment, the motor drive circuit 52 and the control circuit 54 are integrated into the blower box 2. To explain this structure further, as shown in FIG. 4, one side of the blower box 2 is covered with a cover 57. This cover 57 forms a circuit storage chamber 58 between it and one side of the blower box 2 . The upper part of the circuit storage chamber 58 faces the suction passage 4 through a communication port 59 opened at the upper part of one side of the blower box 2 . A printed wiring board 60 is housed in the circuit storage chamber 58 . The printed wiring board 60 is supported on one side of the blower box 2, and its upper end reaches the communication port 59. A plate-shaped heat sink 61 is attached to the upper end of this printed wiring board 60. The heat sink 61 is connected to the communication port 59.
It is exposed to the suction passage 4 of the blower box 2 through the fan 40, and is forcibly cooled by coming into contact with the air flowing through the suction passage 4 when the blower fan 40 rotates. Then, the motor drive circuit 5 is mounted on the printed wiring board 60.
2 and various circuit components 62 constituting the control circuit 53 are mounted, as well as the circuit storage chamber 5 of the heat sink 61.
A switching element 63 (transistor) of the motor drive circuit 52 that switches the current to the stator 15 is attached to the surface facing the stator 8 . This switching element 63 is in surface contact with the heat sink 61. Therefore, the switching element 63 is connected to the heat sink 61
Heat is exchanged with the cold air that has just flown into the suction passage 4 through the switching element 63, thereby increasing the cooling efficiency of the switching element 63.

In FIG. 3, reference numeral 65 indicates a signal cable that electrically connects the circuit component 62 or switching element 63 to each sensor 51, 53 on the circuit board 50.

According to the blower 1 having such a configuration, the rotor magnet 21 is connected via the detection sensor 51 and the rotary disk 36.
The rotational position of the motor is detected magnetically, and a signal indicating this rotational position is input to the motor drive circuit 52. This motor drive circuit 52 energizes the windings 17 of the stator 15 according to the rotational position of the rotor magnet 21, so that the stator 15
Since the phase of the rotor 19 is sequentially switched, the rotor 19
It is continuously driven to rotate at a high speed of 00 rpm or higher. This rotation of the rotor 19 causes the blower fan 40 to rotate integrally, and the air in the suction passage 4 is sucked into the rotational center of the blower fan 40 through the suction port 44. This air is blown out from the outer periphery of the blower fan 40 into the fan cover 42 , and is also discharged from there into the discharge passage 5 through the discharge port 45 of the support wall 43 , and flows inside the discharge passage 5 along the case 11 of the brushless motor 10 . After flowing, it is discharged to the outside of the blower box 2 through the discharge port 5a.

In the electric blower 1 having the above configuration, the detection sensor 51 for detecting the rotational position of the rotor magnet 21 is housed in a sealed second chamber 32 that is separated from the stator 15 that generates heat. Therefore, the thermal influence of the stator 15 on the detection sensor 51 is reduced. Therefore, the temperature rise of the detection sensor 51, which is sensitive to heat, such as a Hall element, can be suppressed, and the reliability of the operation of the detection sensor 51 is increased.

[0026] Also, in this sealed second chamber 32,
Since the temperature sensor 53 for detecting the ambient temperature of the detection sensor 51 is housed, this temperature sensor 53 is connected to the air blower box 2.
No need for direct exposure to internal air flow. Therefore, the temperature sensor 53 is not affected by the temperature of the air flowing through the discharge passage 5 of the blower box 2, and the temperature difference between the installation part of the detection sensor 51 and the installation part of the temperature sensor 53 can be eliminated.

Furthermore, the detection sensor 51 and the temperature sensor 53
Since the sensors 53 are housed adjacent to each other in the same closed space, changes in the ambient temperature of the detection sensor 51 can be directly and sensitively detected.
The responsiveness of the system will be significantly improved. From this,
The ambient temperature of the detection sensor 51 can be detected with high accuracy, and if this ambient temperature exceeds the guaranteed temperature of the detection sensor 51, the rotation of the rotor 19 can be immediately stopped or the rotation can be shifted to deceleration operation. can. Therefore, it is possible to reliably prevent thermal damage or malfunction of the detection sensor 51, and there is an advantage that the rotation of the rotor 19 and eventually the blower fan 40 is stabilized.

Furthermore, in the above embodiment, since the temperature sensor 53 is attached using the circuit board 50 that supports the detection sensor 51, there is no need for special parts or attachment parts to support the temperature sensor 53. The structure can be simplified accordingly.

In the above embodiment, the rotational position of the rotor is magnetically detected using a rotating disk having a plurality of magnetic poles and a Hall element, but the present invention is not limited to this. A slit may be provided in the rotating disk, and light emitting diodes and phototransistors may be provided on both sides of the rotating disk to optically detect the rotational position of the rotor.

[0030]

Effects of the Invention According to the present invention described in detail above, the temperature sensor does not need to be directly exposed to the flow of air sent by the blower fan, so the temperature sensor is not affected by the temperature of the air, and the detection It is possible to eliminate the temperature difference between the sensor installation area and the temperature sensor installation area. Moreover,
Since the detection sensor and the temperature sensor are housed in the same sealed space, changes in the ambient temperature of the detection sensor can be directly and sensitively detected, and responsiveness to temperature changes is significantly improved. Therefore, since the ambient temperature of the detection sensor can be detected with high accuracy, it is possible to reliably prevent thermal damage or malfunction of the detection sensor, and there is an advantage that the rotation of the rotor and thus the blower fan is extremely stable.

[Brief explanation of the drawing]

FIG. 1 is an overall sectional view of an electric blower.

FIG. 2 is an enlarged cross-sectional view of a second chamber of the brushless motor.

FIG. 3 is a diagram showing the positional relationship between a detection sensor and a temperature sensor on a circuit board.

FIG. 4 is a cross-sectional view of the brushless motor installed inside the blower box.

FIG. 5 is a diagram showing the arrangement of switching elements as seen from the direction of line A in FIG. 4;

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 10... Brushless motor, 11... Case, 15... Stator, 19... Rotor, 20... Rotor shaft, 31... First chamber,
32...Second chamber, 36...Rotary plate, 40...Blower fan, 5
1...Detection sensor, 52...Motor drive circuit, 53...Temperature sensor.

Claims (1)

[Claims] 1. A brushless motor including a stator housed in a case and a rotor inserted inside the stator, one end of the rotor shaft of the rotor,
In addition to leading out of the case, a blower fan is provided at one end of the rotor shaft to rotate integrally with the rotor,
The flow path of the air blown by this fan is
In the electric blower located outside the case, the inside of the case of the motor has a first chamber that accommodates a stator, and a first chamber that has a sealed structure that is partitioned from the first chamber and the air flow path. This second room is divided into two rooms, the second room and the second room.
The other end of the rotor shaft is introduced into the second chamber.
A rotating disk for rotor position detection that rotates together with the rotor is provided at the other end of the rotor shaft introduced into the second chamber.
The chamber includes a detection sensor that faces the rotary disk and detects the rotational position of the rotor from the rotary disk, and a sensor that detects the ambient temperature of the detection sensor and detects when the ambient temperature exceeds the permissible limit. An electric blower characterized in that a temperature sensor is provided for outputting a control signal to a control circuit that controls a drive circuit of the motor.