JP2013057286A - Electric blower and vacuum cleaner using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electric blower which achieves the cooling of the bearing of a brushless motor with a compact and low-loss structure when operating at a high-speed revolution and has high air-sending performance and high reliability and further to provide a vacuum cleaner using the same.SOLUTION: The electric blower includes: a brushless motor 7 made up of a rotor 3 with a rotary shaft 2a, a stator 4 oppositely arranged on the periphery of the rotor 3, and a motor frame 6 for holding the bearing 5 of the rotary shaft 2a and covering the stator 4; an impeller 8 fixed to the rotating shaft 2a; an air guide 9 for forming an airflow path on the periphery of the impeller 8; and a fan case 10 fixed to a foreface of the air guide 9 to cover the impeller 8. The rotary shaft 2a is formed with a double structure including a heat dissipating shaft 11a and a spindle 12a to transfer heat generated in the bearing 5 to the heat dissipating shaft 11a of the rotary shaft 2a, enabling the heat to be continuously dissipated to an air current inflowing from the impeller 8. Therefore, the bearing 5 is efficiently cooled even at the high-speed revolution to prevent a seizure by curbing an excessive temperature rise, thus permitting the electric blower with a compact and high air-sending performance to be achieved.

Description

  The present invention relates to an electric blower that realizes cooling of a brushless motor bearing during high-speed rotation with a small and low-pressure loss configuration and has high blowing performance and reliability, and an electric vacuum cleaner using the electric blower.

  Conventionally, as a bearing cooling mechanism of this type of electric blower, cooling by supplying a cooling liquid to a bearing or forced cooling using air is known, and cooling is performed by transferring the heat of the bearing to a rotating shaft. Many mechanisms are also used. (For example, refer to Patent Documents 1 and 2).

  The input power of household vacuum cleaners is limited, and it is necessary to improve the blowing performance of the electric blower in order to obtain a stronger suction force. At the same time, from the viewpoint of easy cleaning, it is desired that the vacuum cleaner body has a small turn, and it is necessary to reduce the size of the electric blower.

  In order to reduce the size of the electric blower, it is necessary to rotate the impeller at high speed to reduce the diameter of the impeller.However, as the number of rotations increases, the effect of the unbalance amount of the impeller increases, and the load on the bearing increases. As the number of contacts increases, the number of times of contact between the rolling elements and the inner and outer rings increases, and the temperature of the bearing due to friction rises, causing seizure.

  In addition, when attempting to cool the bearing through the airflow generated by the impeller inside the motor, bending loss increases and the performance of the electric blower decreases, so it is difficult to achieve both the performance of the electric blower and downsizing.

  FIG. 11 is a diagram illustrating a cross-sectional configuration of a blower using the conventional bearing cooling mechanism described in Patent Document 1. In FIG. A bottomed cylindrical rotating shaft 35 on which the bearing 34 is fitted, a pipe 36 inserted into the rotating shaft 35, and a spiral interposed between the inner peripheral surface of the rotating shaft 35 and the outer peripheral surface of the pipe 36. And by rotating the intake / exhaust fin 37 in association with the rotary shaft 35, the pipe 36 or the outer peripheral surface of the pipe 36 and the inner peripheral surface of the rotary shaft 35 are rotated. A high-speed rotating shaft 35 is configured to cool the rotating shaft 35 and the bearing 34 by exhausting the cooling gas sucked from either one of the air passages 38 formed therebetween to the other side. A blower 39 using a cooling mechanism for the bearing 34 is disclosed.

  FIG. 12 is a view showing a cross-sectional configuration of a high-temperature gas blower using the conventional bearing cooling mechanism described in Patent Document 2. As shown in FIG. A blower provided with an impeller 43 mounted on the fixed shaft 40 by a motor including a rotor 41 rotatably provided on the fixed shaft 40 and a stator 42 provided on the rotor 41 so as to be rotatable in the blower casing 44. 45, the impeller 43 is made of a heat-resistant material such as a ceramic sintered body or a heat-resistant alloy and connected to the rotor 41, and spiral groove radial dynamic pressure bearing portions 46 are formed and supported at both ends of the rotor 41 of the motor. In addition, a high-temperature gas blower 45 including a cooling pipe 47 for cooling in the fixed shaft 40 is disclosed.

JP 2007-192265 A Japanese Patent Laid-Open No. 1-249991

  However, in the configuration of the blower using the conventional bearing cooling mechanism described in Patent Document 1, since the helical intake and exhaust fins are provided between the inner peripheral surface of the rotating shaft and the outer peripheral surface of the pipe, In addition to the torque required to rotate the fan, the torque required to rotate the intake fin is required, and bearing cooling during high-speed rotation is possible, but the torque required for the rotating shaft is generally the square of the number of rotations. Therefore, the required torque is significantly increased, and the performance of the blower is degraded.

  Moreover, in the structure of the high-temperature gas blower using the conventional bearing cooling mechanism described in Patent Document 2, a heat exchanger is required to dissipate heat from the cooling pipe built in the rotating shaft, and the size increases. For this reason, it has been difficult to accommodate in a household vacuum cleaner, and it has been difficult to apply.

  That is, the conventional bearing cooling mechanisms described in Patent Documents 1 and 2 have a problem that the performance and miniaturization of the electric blower cannot be realized.

  The present invention solves the above-mentioned conventional problems, and realizes cooling of a brushless motor bearing during high-speed rotation with a small and low-pressure loss configuration, and uses an electric blower having high blowing performance and reliability and the same. An object is to provide a vacuum cleaner.

  In order to solve the above-described conventional problems, an electric blower of the present invention includes a rotor having a rotating shaft, a stator disposed opposite to the outer periphery of the rotor, and a motor frame that holds a bearing of the rotating shaft and covers the stator. A brushless motor, an impeller fixed to the rotating shaft, an air guide that forms a ventilation path on an outer periphery of the impeller, and a fan case that covers the impeller and is fixed to the front surface of the air guide. The shaft is formed of a double structure of a heat dissipation shaft and a main shaft made of different materials, the heat dissipation shaft is built in a state in contact with the hollow portion of the main shaft, and the heat conductivity of the heat dissipation shaft is larger than the main shaft, The end of the heat dissipating shaft protrudes beyond the end of the main shaft and is located in the internal flow path of the impeller or upstream thereof.

  As a result, when the brushless motor is driven at high speed, the airflow flowing into the impeller always passes around the heat dissipating shaft protruding from the end of the main shaft, and the heat of the bearing is directed to the rotating shaft in contact with the inner ring. As a result, a temperature difference occurs between the end of the heat dissipation shaft and the bearing contact portion, and the heat of the bearing is conducted through the heat dissipation shaft to the end of the lower temperature, and the heat is dissipated from the periphery of the end in contact with the airflow. Thus, the temperature rise of the bearing during high-speed rotation can be suppressed, and a small electric blower having high air blowing performance can be realized.

  In addition, since the electric vacuum cleaner of the present invention is equipped with an electric blower having a highly reliable bearing and a small size and high air blowing performance, it has a strong suction force and good dust removal, and is easy to use with a small turn. Is a good vacuum cleaner.

In the electric blower of the present invention, the rotating shaft is formed by a double structure of the heat radiating shaft and the main shaft, the heat generated by the bearing is transmitted to the heat radiating shaft of the rotating shaft, and the heat is continuously radiated to the airflow flowing from the impeller. Therefore, even during high-speed rotation, the bearing can be efficiently cooled to suppress excessive temperature rise to prevent seizure, and a small electric blower having high air blowing performance can be realized.
Moreover, the electric vacuum cleaner using such an electric blower has a strong suction force, good dust removal, and a lightweight electric blower.

The partial cross section figure of the electric blower in the 1st Embodiment of this invention The partial cross-sectional perspective view of the rotating shaft of the electric blower Development of electric blower The partial cross-sectional perspective view of the impeller of the electric blower Sectional drawing showing the structure of the electric vacuum cleaner using an electric blower Partial sectional drawing of the electric blower in the 2nd Embodiment of this invention The partial cross-sectional perspective view of the rotating shaft of the electric blower The partial cross-sectional perspective view of the rotating shaft of the electric blower Partial sectional drawing of the electric blower in the 3rd Embodiment of this invention The partial cross-sectional perspective view of the rotating shaft of the electric blower Cross section of a conventional electric blower Cross section of a conventional electric blower

According to a first aspect of the present invention, there is provided a brushless motor including a rotor having a rotating shaft, a stator disposed opposite to the outer periphery of the rotor, a motor frame holding a bearing of the rotating shaft and covering the stator, and fixed to the rotating shaft And a fan case that covers the impeller and is fixed to the front surface of the air guide, and the rotating shaft includes a heat dissipation shaft and a main shaft that are made of different materials. The heat dissipating shaft is built in a state of being in contact with the hollow portion of the main shaft, the heat conductivity of the heat dissipating shaft is larger than that of the main shaft, and the upper end of the heat dissipating shaft is the upper end of the main shaft. The electric blower is configured to protrude from the portion and to be located in the internal flow path of the impeller or upstream thereof.
As a result, when the brushless motor is driven at high speed, the airflow generated by the rotation of the impeller always flows around the upper end of the heat dissipation shaft protruding from the upper end of the main shaft and flows into the impeller. Therefore, the temperature of the upper end portion of the heat dissipation shaft is lowered, and a temperature difference is generated between the upper end portion of the heat dissipation shaft and the bearing contact portion. Therefore, a temperature gradient is created inside the heat dissipation shaft, and the heat of the bearing is low. The inside of the heat dissipation shaft is conducted to the upper end portion of the heat dissipation shaft, and heat can be radiated from the periphery of the upper end portion of the heat dissipation shaft.
Thereby, excessive temperature rise of the bearing during high-speed rotation can be suppressed, and seizure of the bearing can be prevented. In addition, since it has a simple bearing cooling configuration in which the heat of the bearing is dissipated to the airflow through the heat radiating shaft of the rotating shaft, it is possible to realize a small electric blower that does not require a heat exchanger or the like and has high air blowing performance. .

  According to a second aspect of the invention, in particular, in the first aspect of the invention, the main shaft has a plurality of radial holes on the surface in contact with the bearing, and a plurality of holes are filled with a heat radiator having a higher thermal conductivity than the main shaft. Therefore, the heat resistance between the bearing and the radiating shaft facing the bearing is reduced, and the heat flow from the bearing to the radiating shaft is increased, so the heat from the bearing is easily radiated and the bearing is cooled more efficiently. The reliability of the bearing can be improved.

  In the third invention, particularly in the first or second invention, the heat dissipating shaft has a structure in which both end portions protrude from both end portions of the main shaft and the lower end portion protrudes from the lower end of the motor frame. Not only the upper end of the heat dissipation shaft that contacts the airflow flowing into the impeller, but also the temperature difference between the lower end of the heat dissipation shaft protruding from the lower end of the motor frame and the bearing abutment, a temperature gradient is created inside the heat dissipation shaft. The heat can be radiated from both ends of the heat radiating shaft.

  According to a fourth aspect of the present invention, in particular, in any one of the first to third aspects, the heat dissipation shaft has a plurality of grooves on the outer peripheral surface thereof, and fits with the plurality of grooves provided on the inner peripheral surface of the main shaft. Because the contact area between the outer peripheral surface of the heat dissipation shaft and the inner peripheral surface of the main shaft is increased, the contact thermal resistance is reduced, and the heat flow from the bearing is increased, which makes it easier to dissipate the heat of the bearing. The bearing can be cooled more efficiently.

  In a fifth aspect of the invention, in any one of the first to fourth aspects of the invention, the main shaft has a plurality of radial holes on a surface in contact with the rotor, and a plurality of heat dissipating bodies having a higher thermal conductivity than the main shaft are provided. Since the hole is filled, the thermal resistance between the rotor and the heat dissipation shaft facing the rotor is reduced, and the heat flow from the rotor to the heat dissipation shaft is increased, making it easier to dissipate the heat of the rotor. Not only the bearing but also the rotor can be cooled, and thermal demagnetization due to excessive temperature rise of the rotor can be prevented.

  The sixth aspect of the invention is a vacuum cleaner equipped with the electric blower of any one of the first to fifth aspects of the invention, so that it has a strong suction force and good dust removal, and the main body size is small so It becomes a vacuum cleaner that is easy to use and convenient.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. Note that the present invention is not limited to the embodiments.

(Embodiment 1)
FIGS. 1-5 shows the structure of the electric blower in Embodiment 1 of this invention. 1 is a partial cross-sectional view of the electric blower, FIG. 2 is a partial cross-sectional perspective view of a rotating shaft of the electric blower, FIG. 3 is a development view of the electric blower, and FIG. 4 is the electric blower. FIG. 5 is a cross-sectional view illustrating a configuration of a vacuum cleaner using the electric blower.

  As shown in FIG. 1, the electric blower 1 a includes a rotor 3 having a rotating shaft 2 a, a stator 4 disposed opposite to the outer periphery of the rotor 3, and a motor frame 6 that holds the bearing 5 of the rotating shaft 2 a and covers the stator 4. A brushless motor 7, an impeller 8 fixed to the rotating shaft 2 a, an air guide 9 that forms a ventilation path on the outer periphery of the impeller 8, and a fan case 10 that covers the impeller 8 and is fixed to the front surface of the air guide 9. As shown in FIG. 2, the rotating shaft 2a is formed with a double structure of an aluminum heat dissipating shaft 11a and a steel main shaft 12a. The main shaft 12a has a hollow portion and the heat dissipating shaft 11a is connected to the main shaft 12a. The outer peripheral surface of the heat radiating shaft 11 a is in contact with the hollow portion, and the upper end portion of the heat radiating shaft 11 a protrudes from the upper end portion of the main shaft 12 a and is further upstream than the upper portion of the impeller 8.

  As shown in FIG. 3, the air guide 9 has a plurality of guide vanes 13 and is fixed in a state where the fan case 10 abuts on the upper surface thereof, and an independent air passage 14 is formed between the guide vanes 13. Each of the independent air passages 14 has a channel cross-sectional area that continuously increases from the outer periphery of the impeller 8 to the outer periphery of the air guide 9.

  As shown in FIG. 4, the impeller 8 is configured by sandwiching an inducer 17 having a three-dimensional wing and a plurality of blades 18 between a sheet metal front shroud 15 and a rear shroud 16 facing the front shroud 15. Yes. Further, as shown in FIG. 1, a rolling bearing 5 having a feature of low friction torque is used as the bearing 5. The rolling bearing 5 has an inner ring 19 and an outer ring 20, and a rolling element 21 is interposed between the inner ring 19 and the outer ring 20, and a rotational load is supported by the rolling of the rolling element 21. The front end of the inlet of the impeller 8 is dynamically sealed by contacting the PTFE resin ring 22 in a state where the impeller 8 can be driven to rotate.

In FIG. 5, the vacuum cleaner 23 includes a vacuum cleaner main body 28 having a dust collection chamber 25 communicating with the main body intake port 24 and a blower chamber 27 having a main body exhaust port 26, and a main body intake port 24 in the dust collection chamber 25. A dust bag 29 that is airtightly installed, an electric blower 1 a installed in the blower chamber 27, a soundproof cover 30 made of a flame-retardant resin that covers the electric blower 1 a, and a sound-absorbing material disposed above and below the blower chamber 27. 31. Although not shown, a hose and an extension pipe (not shown) are sequentially connected to the main body intake port 24, and a nozzle (not shown) for sucking dust on the floor is attached to the tip of the extension pipe.
Is attached.

  About the electric blower 1a comprised as mentioned above and the vacuum cleaner 23 using the same, the operation | movement and an effect | action are demonstrated below.

  First, the operation of the electric blower 1a will be described. In FIG. 1, a rotating magnetic field is generated by exciting the winding 32, the rotor 3 rotates in synchronization with the rotating magnetic field, and the impeller 8 fixed to the rotating shaft 2a rotates. By rotating the impeller 8, the air inside the impeller 8 is pushed to the outer periphery of the impeller 8 by the three-dimensional blade and the plurality of blades 18, the inside of the impeller 8 becomes negative pressure, and an airflow flowing into the impeller 8 is generated. To do. The airflow flows axially from the inlet of the impeller 8 and flows along a plurality of internal flow paths formed by the inducer 17, the plurality of blades 18, the front shroud 15, and the rear shroud 16, and then to the outer periphery of the impeller 8. leak.

  The airflow that has flowed out of the impeller 8 flows into the independent air passages 14 formed by the plurality of guide vanes 13 in the air guide 9 and flows toward the outer periphery of the air guide 9. At that time, since the flow passage cross-sectional area of each independent air passage 14 increases from the outer periphery of the impeller 8 to the outer periphery of the air guide 9, the dynamic pressure is converted to static pressure while the flow velocity of the airflow flowing through the independent air passage 14 is reduced. Is done.

  The blowing performance of the electric blower 1a is determined by the electric power input to rotationally drive the impeller 8 and the work performed by the electric blower 1a (the air output obtained by the product of the degree of vacuum and the flow rate generated by the rotation of the impeller 8). It is expressed as a ratio. For this reason, increasing the degree of vacuum (static pressure) generated by the electric blower 1a at the actual flow rate is very important for improving the blowing performance of the electric blower 1a. In order to reduce the size of the electric blower 1a, it is necessary to rotate the impeller 8 at a high speed to reduce the diameter. Although the conventional electric blower 1a is driven at less than 50,000 rpm, further reduction in size requires high-speed rotation of 50,000 rpm or more, and the brushless motor 7 having no brush sliding loss is suitable.

  On the other hand, since the influence of the unbalance of the impeller 8 on the rotating shaft 2a increases due to the increase in the rotational speed, the rotating shaft 2a easily swings and the load on the bearing 5 increases, and the rolling element There is a problem that the number of times of contact between the inner ring 19 and the outer ring 20 increases and the temperature of the bearing 5 rises excessively due to friction and the bearing 5 is seized.

  For this reason, during high-speed rotation, it is very important to efficiently cool the bearing 5 to suppress the temperature rise. On the other hand, when the airflow from the impeller 8 is caused to flow inside the brushless motor 7 to cool the bearing 5, the radius of curvature at which the airflow bends is small, the bending loss increases, and the performance of the electric blower 1a is greatly reduced. In order to achieve both performance and miniaturization of the electric blower 1a, a configuration that can efficiently dissipate the heat of the bearing 5 to the outside of the brushless motor 7 is necessary.

  The temperature rise of the bearing 5 is caused by the heat generated by the friction between the rolling element 21 and the inner ring 19 and the outer ring 20 and the heat around the bearing 5 inside the brushless motor 7 being transmitted to the bearing 5. The heat of the bearing 5 is conducted to the main shaft 12a in contact with the inner ring 19, and then conducted to the heat radiating shaft 11a.

  Since the airflow generated by the rotation of the impeller 8 always passes around the upper end of the heat dissipation shaft 11a protruding from the upper end of the main shaft 12a and flows into the impeller 8, the temperature of the upper end of the heat dissipation shaft 11a Since a temperature difference is generated between the upper end portion of the heat radiating shaft 11a and the contact portion of the bearing 5, a temperature gradient is created inside the heat radiating shaft 11a, and the heat of the bearing 5 is the upper end of the heat radiating shaft 11a having a low temperature. The inside of the heat radiating shaft 11a is conducted to the part, and heat can be radiated from the vicinity of the upper end portion of the heat radiating shaft 11a.

Thereby, the excessive temperature rise of the bearing 5 during high-speed rotation can be suppressed and seizure of the bearing 5 can be prevented. The bearing 5 has a simple bearing cooling structure in which the heat of the bearing 5 is radiated to the airflow through the heat radiating shaft 11a of the rotating shaft 2a, and does not require a heat exchanger or the like and does not cause pressure loss with respect to the airflow flowing into the impeller 8. Therefore, the electric blower 1a having a small size and high blowing performance can be realized.
In addition to aluminum, there are metals such as copper, silver, gold, and brass as well as inorganic materials such as beryllia, silicon, and aluminum nitride.

  Next, the operation of the electric vacuum cleaner 23 will be described. In FIG. 5, when the impeller 8 of the electric blower 1a is rotated, the dust collection chamber 25 is in a negative pressure state, and an air flow including dust sucked from a nozzle (not shown) passes through the main intake port and is collected. 25. The clean airflow filtered and separated by the dust bag 29 flows into the impeller 8 of the electric blower 1a, passes through a plurality of air passages provided in the ventilation passage, and then flows out from the exhaust port of the soundproof cover 30. It is discharged to the outside of the cleaner main body 28 through the main body exhaust port 26. Since the electric vacuum cleaner 23 is equipped with a small and highly efficient electric blower 1a, the vacuum cleaner 23 has a strong suction force, good dust removal, a small body size of the electric blower 1a, and a small turn, which is convenient to use. Is good. Further, by extending the sound absorption area and the exhaust passage in the cleaner main body 28, it is possible to make the electric cleaner 23 with a low operation sound.

  As described above, in the present embodiment, the rotary shaft 2a has a double structure of the aluminum heat dissipation shaft 11a and the steel main shaft 12a, and the heat of the bearing 5 during high speed rotation is conducted to the heat dissipation shaft 11a. Thus, heat dissipation is performed by generating a temperature difference between the upper end portion of the heat dissipation shaft 11a and the bearing 5 contact portion by dissipating heat from the vicinity of the upper end portion of the heat dissipation shaft 11a to the airflow flowing into the impeller 8. Since the bearing 5 can be constantly cooled by promoting, excessive temperature rise of the bearing 5 can be suppressed and seizure of the bearing 5 can be prevented.

(Embodiment 2)
6 and 7 show the configuration of the electric blower 1b according to Embodiment 2 of the present invention. 6 is a partial cross-sectional view of the electric blower 1b, and FIG. 7 is a partial cross-sectional perspective view of the rotating shaft 2b of the electric blower 1b. Note that the same elements as those of the first embodiment are denoted by the same reference numerals and description thereof is omitted.

  6 and 7, the rotating shaft 2b of the electric blower 1b is formed by pouring high-temperature aluminum into a hollow portion of a steel main shaft 12b in which a plurality of holes are provided radially on the contact surface with the bearing 5, It has a double structure made by die casting in which the hollow portion and all radial holes are filled with aluminum. The outer peripheral surface of the aluminum filled in the plurality of holes has substantially the same surface as the outer peripheral surface of the main shaft 12b, and the inner ring 19 of the bearing 5 is in contact therewith. Further, both end portions of the heat radiating shaft 11b protrude from both end portions of the main shaft 12b, and the upper end portion of the heat radiating shaft 11b is in a position protruding from the upper portion of the impeller 8, while the lower end portion of the heat radiating shaft 11b protrudes from the lower end of the motor frame 6. Has a configuration. In addition, in order to simply explain aluminum filled in a plurality of holes provided in a radial manner, the aluminum is hereinafter referred to as a heat radiator 33.

  About the electric blower comprised as mentioned above, the operation | movement and an effect | action are demonstrated below.

  First, the operation of the electric blower 1b will be described. In FIG. 6, a rotating magnetic field is generated by exciting the winding 32, the rotor 3 rotates in synchronization with the rotating magnetic field, and the impeller 8 fixed to the rotating shaft 2b rotates. By rotating the impeller 8, the air inside the impeller 8 is pushed to the outer periphery of the impeller 8 by the three-dimensional blade and the plurality of blades 18, the inside of the impeller 8 becomes negative pressure, and an airflow flowing into the impeller 8 is generated. To do. The airflow flows in the axial direction from the inlet of the impeller 8, flows along a plurality of internal flow paths of the impeller 8, and then flows out to the outer periphery of the impeller 8.

  The temperature rise of the bearing 5 occurs when heat due to friction between the rolling elements 21 and the inner ring 19 and the outer ring 20 and heat around the bearing 5 inside the brushless motor 7 are transmitted to the bearing 5. Since the heat radiating body 33 is made of aluminum, the heat conductivity is larger than that of the main shaft 12b, and the heat of the bearing 5 is transmitted to the heat radiating shaft 11b through the plurality of heat radiating bodies 33 in contact with the inner ring 19 of the bearing 5. .

  The air flow generated by the rotation of the impeller 8 always passes around the upper end portion of the heat dissipation shaft 11b protruding from the upper portion of the impeller 8 and flows into the impeller 8, so the temperature of the upper end portion of the heat dissipation shaft 11b becomes lower. A temperature difference occurs between the upper end portion of the heat radiating shaft 11b and the bearing 5 contact portion. Further, since the lower end portion of the heat radiating shaft 11b protrudes from the lower end of the motor frame 6 and is in contact with air at normal temperature, the temperature is lower than the contact portion of the bearing 5, and a temperature difference occurs between the lower end portion of the heat radiating shaft 11b.

  As a result, a temperature gradient is generated between the both end portions and the bearing 5 contact portion inside the heat radiating shaft 11b, and the heat of the bearing 5 is conducted through the heat radiating shaft 11b and flows into the impeller 8 from both ends. And is dissipated into the air. Since the periphery of the upper end portion of the heat radiating shaft 11b is constantly forcedly cooled by the airflow flowing into the impeller 8, the temperature is lower than the end portion of the heat radiating shaft 11b protruding from the lower end of the motor frame 6, so that the heat of the bearing 5 Most of the heat is radiated from the end of the heat dissipation shaft 11b to the airflow. Since the heat dissipating body 33 exists between the bearing 5 and the heat radiating shaft 11b, the heat resistance between the heat radiating shaft 11b and the bearing 5 is greatly reduced, and the heat flow transmitted from the bearing 5 to the heat radiating shaft 11b is increased. Since it becomes large, it becomes easy to radiate the heat of the bearing 5.

  Thereby, the excessive temperature rise of the bearing 5 and the rotor 3 during high-speed rotation is suppressed, the excessive temperature rise of the bearing 5 during high-speed rotation is suppressed, the seizure of the bearing 5 is prevented, and the reliability of the bearing 5 is improved. be able to. In addition, the bearing 5 has a simple bearing cooling structure in which the heat of the bearing 5 is radiated through the heat radiating shaft 11b of the rotating shaft 2b, and does not require a heat exchanger or the like, and does not cause pressure loss with respect to the airflow flowing into the impeller 8. It can be set as the electric blower 1b which is small and has high ventilation performance.

  As described above, in the present embodiment, the rotary shaft 2b has a double structure of the aluminum heat dissipation shaft 11b and the steel main shaft 12b, and a plurality of radial shafts provided on the main shaft 12b facing the bearing 5 are provided. By filling the hole with the heat radiating body 33 having high thermal conductivity, the heat resistance between the bearing 5 and the heat radiating shaft 11b facing the bearing 5 is reduced, and the heat flow transmitted from the bearing 5 to the heat radiating shaft 11b is increased. 5 can be further suppressed, and the reliability of the bearing 5 can be improved.

  In the present embodiment, the example of the electric blower 1b using the rotary shaft 2b in which the contact surface between the heat dissipation shaft 11b and the main shaft 12b is cylindrical has been described. However, as shown in FIG. The rotary shaft 2c having a shape and a double structure may be used. The contact area between the outer peripheral surface of the heat radiating shaft 11c and the inner peripheral surface of the main shaft 12c is increased, the contact thermal resistance is reduced, and the heat flow from the bearing 5 is further increased. Since it becomes large, the heat | fever of the bearing 5 can be radiated easily and bearing cooling can be performed more efficiently.

(Embodiment 3)
9 and 10 show the configuration of the electric blower 1c according to Embodiment 3 of the present invention. FIG. 9 is a partial sectional view of the electric blower 1c, and FIG. 10 is a partial sectional perspective view of the rotating shaft 2d of the electric blower 1c. In addition, about the same element as Embodiment 1, 2, the same code | symbol is attached | subjected and the description is abbreviate | omitted.

9 and 10, the rotating shaft 2 d of the electric blower 1 c flows high-temperature heated aluminum into the hollow portion of the steel main shaft 12 d in which a plurality of holes are provided radially on the contact surface with the bearing 5 and the rotor 3. The hollow portion of the main shaft 12d and all radial holes have a double structure made by die casting in which aluminum is filled. The outer peripheral surface of aluminum filled in the plurality of radial holes has substantially the same surface as the outer peripheral surface of the main shaft 12d, and the inner ring 19 of the bearing 5 and the rotor 3 are in contact with each other. Hereinafter, the aluminum filled in the plurality of radial holes will be referred to as a heat radiating body 33 for simple explanation.

  About the electric blower comprised as mentioned above, the operation | movement and an effect | action are demonstrated below.

  First, the operation of the electric blower 1c will be described. In FIG. 9, by rotating the impeller 8, the air inside the impeller 8 is pushed to the outer periphery inside the impeller 8 by the three-dimensional blade and the plurality of blades 18, and the inside of the impeller 8 becomes negative pressure and enters the impeller 8. A flowing air flow is generated. The airflow flows in the axial direction from the inlet of the impeller 8, flows along a plurality of internal flow paths of the impeller 8, and then flows out to the outer periphery of the impeller 8.

  Since the heat radiating body 33 is made of aluminum, the heat conductivity is larger than that of the main shaft 12d, and the heat of the bearing 5 is transmitted to the heat radiating shaft 11d through the plurality of heat radiating bodies 33 in contact with the inner ring 19 of the bearing 5. . In addition, although heat is generated by eddy current in the rotor 3 rotating at high speed, the heat of the rotor 3 is conducted through the heat radiating body 33 in contact with the rotor 3 and transmitted to the heat radiating shaft 11d as in the bearing 5.

  The air flow generated by the rotation of the impeller 8 always passes around the upper end of the heat dissipation shaft 11d protruding from the upper part of the impeller 8 and flows into the impeller 8, so the temperature of the upper end of the heat dissipation shaft 11d is lowered. A temperature difference occurs between the upper end portion of the heat dissipation shaft 11d, the bearing 5 contact portion, and the rotor 3 contact portion. Further, since the lower end portion of the heat radiating shaft 11d protrudes from the lower end of the motor frame 6 and is in contact with air at room temperature, the temperature is lower than the bearing 5 contact portion and the rotor 3 contact portion, and the lower end portion of the heat radiating shaft 11d A temperature difference occurs.

  As a result, a temperature gradient is generated between both ends, the bearing 5 contact portion, and the rotor 3 contact portion inside the heat dissipation shaft 11d, and the heat of the bearing 5 and the rotor 3 is conducted inside the heat dissipation shaft 11d. Heat is dissipated into the airflow and air flowing into the impeller 8 from both ends. Since the periphery of the upper end portion of the heat radiating shaft 11d is constantly forcedly cooled by the airflow flowing into the impeller 8, the temperature is lower than the end portion of the heat radiating shaft 11d protruding from the lower end of the motor frame 6, so that the bearing 5 and the rotor 3 Most of the heat is radiated from the end of the heat dissipation shaft 11d to the airflow.

  Since the heat radiating body 33 exists between the bearing 5 and the rotor 3 and the heat radiating shaft 11d, the thermal resistance between the bearing 5 and the heat radiating shaft 11d facing the rotor 3 is significantly reduced. Since the heat flow transmitted to the heat dissipating shaft 11d increases, the heat of the bearing 5 and the rotor 3 can be easily dissipated. Thereby, the excessive temperature rise of the bearing 5 and the rotor 3 during high-speed rotation can be suppressed, the burning of the bearing 5 and the thermal demagnetization of the rotor 3 can be prevented, and the reliability of the brushless motor 7 can be improved.

  Moreover, it is a simple cooling configuration in which the heat of the bearing 5 and the rotor 3 is dissipated through the heat radiating shaft 11d of the rotating shaft 2d, does not require a heat exchanger, and does not cause pressure loss with respect to the airflow flowing into the impeller 8. Therefore, it can be set as the electric blower 1c which is small and has high ventilation performance.

As described above, in the present embodiment, the rotary shaft 2d has a double structure of the aluminum heat dissipation shaft 11d and the steel main shaft 12d, and is provided radially on the main shaft 12d facing the bearing 5 and the rotor 3. By filling the plurality of holes with the heat radiating body 33 having high thermal conductivity, the heat flow between the bearing 5 and the rotor 3 and the heat radiating shaft 11d is reduced, and the heat flow transmitted from the bearing 5 to the heat radiating shaft 11d is increased. By increasing the size, not only the bearing 5 but also the heat of the rotor 3 can be efficiently dissipated efficiently, and the reliability of the brushless motor 7 can be improved.
In addition, the structure of each Embodiment 1-3 mentioned above is not limited to this, It can comprise suitably combining as needed.

  As described above, in the electric blower according to the present invention, the rotating shaft is formed with a double structure of the heat radiating shaft and the main shaft, heat generated in the bearing is transmitted to the heat radiating shaft of the rotating shaft, and continuous with the airflow flowing from the impeller. Heat can be efficiently dissipated, the bearings can be efficiently cooled even during high-speed rotation, an excessive temperature rise can be prevented, and seizure can be prevented, and a small and highly efficient electric blower can be realized. Of course, it can be applied to a commercial vacuum cleaner.

1a, 1b, 1c Electric blower 2a, 2b, 2c, 2d Rotating shaft 3 Rotor 4 Stator 5 Bearing 6 Motor frame 7 Brushless motor 8 Impeller 9 Air guide 10 Fan case 11a, 11b, 11c, 11d Radiating shaft 12a, 12b, 12c , 12d Main shaft 13 Guide vane 14 Independent air passage 19 Inner ring 20 Outer ring 21 Rolling element 22 Resin ring 23 Vacuum cleaner 32 Winding 33 Radiator

Claims (6)

A brushless motor composed of a rotor having a rotating shaft, a stator disposed opposite to the outer periphery of the rotor, and a motor frame that holds a bearing of the rotating shaft and covers the stator;
An impeller fixed to the rotating shaft;
An air guide that forms a ventilation path on the outer periphery of the impeller; and
A fan case that covers the impeller and is fixed to the front surface of the air guide;
The rotating shaft is formed of a double structure of a heat radiating shaft and a main shaft made of different materials,
The heat dissipating shaft is housed in a state in contact with the hollow portion of the main shaft,
The electric blower is configured such that the thermal conductivity of the heat dissipating shaft is greater than that of the main shaft, and the upper end portion of the heat dissipating shaft protrudes from the upper end portion of the main shaft and is located in the internal flow path of the impeller or upstream thereof. 2. The electric blower according to claim 1, wherein the main shaft has a plurality of radial holes on a surface in contact with a bearing, and a heat radiator having a higher thermal conductivity than the main shaft is filled in the plurality of holes. 3. The electric blower according to claim 1, wherein both ends of the heat dissipation shaft protrude from both ends of the main shaft, and a lower end of the heat dissipation shaft protrudes from a lower end of the motor frame. The electric fan according to any one of claims 1 to 3, wherein the heat dissipating shaft has a plurality of grooves on an outer peripheral surface thereof and fits with a plurality of grooves provided on an inner peripheral surface of the main shaft. . The said main axis | shaft has a some radial hole in the surface contact | abutted with a rotor, The heat dissipation body whose heat conductivity is higher than the said main axis | shaft was filled with the said some hole. The electric blower described. The vacuum cleaner carrying the electric blower of any one of Claims 1-5.

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