Magnet, and electric motor and cleaner employing same

Abstract

Disclosed is a cleaner comprising: a suction fan that includes a fan motor and an impeller rotated by the fan motor to generate a suction force required to suction foreign substances on a surface being cleaned; and a dust collection bin that accommodates the foreign substances suctioned from the surface being cleaned. The fan motor includes: a rotor assembly that includes a rotary shaft and a magnet fixed to the rotary shaft; and a stator assembly that is disposed around the rotor assembly and spaced apart therefrom so that there is an air gap therebetween. The magnet includes: both end portions that include a first compound having a first magnetic flux density; and a central portion that is located between both the end portions and includes a second compound having a second magnetic flux density greater than the first magnetic flux density.

Description

Magnets, electric motors and vacuum cleaners employing them

[0001] The present disclosure relates to a magnet, an electric motor employing the same, and a vacuum cleaner.

[0002] International Patent Publication No. 2021 / 014260 discloses a rotary motor. The rotary motor comprises a stator having a stator core having slots provided along its entire circumference and a stator winding wound around the stator core, and a rotor arranged to rotate relative to the stator. The rotor comprises electrical steel sheets laminated in the direction of its rotational axis and a rotor core having a plurality of magnetic poles formed in the circumferential direction, and a plurality of first permanent magnets and a plurality of second permanent magnets for forming each of the plurality of magnetic poles. Additionally, the first permanent magnets and the second permanent magnets for forming each magnetic pole of the rotor have different recoil permeabilities.

[0003] A vacuum cleaner according to one aspect of the present disclosure comprises a suction fan and a dust collection container. The suction fan comprises a fan motor and an impeller that generates a suction force necessary to suck up foreign matter on a surface to be cleaned while being rotated by the fan motor. The foreign matter sucked from the surface to be cleaned is received in the dust collection container. The fan motor comprises a rotor assembly and a stator assembly. The rotor assembly comprises a rotating shaft and a magnet fixed to the rotating shaft. The stator assembly is spaced apart from the rotor assembly with an air gap. The magnet comprises two ends and a central portion between them. The two ends comprise a first compound having a first magnetic flux density, and the central portion comprises a second compound having a second magnetic flux density higher than the first magnetic flux density.

[0004] An electric motor according to one aspect of the present disclosure comprises a rotor assembly including a rotating shaft and a magnet fixed to the rotating shaft, and a stator assembly spaced apart from the rotor assembly by an air gap. The magnet comprises two ends including a first compound having a first magnetic flux density and a central portion between the two ends including a second compound having a second magnetic flux density higher than the first magnetic flux density.

[0005] A magnet according to one aspect of the present disclosure is formed by compression molding a compound comprising magnetic powder and a binder. The magnet comprises two ends in the compression direction and a central portion between said ends. The compound at said ends comprises a first compound having a first magnetic flux density, and the compound at said central portion comprises a second compound having a second magnetic flux density higher than the first magnetic flux density.

[0006] FIG. 1 is a schematic diagram of a vacuum cleaner according to one embodiment of the present disclosure.

[0007] FIG. 2 is a schematic diagram of the rotor assembly of a fan motor applied to one embodiment of the vacuum cleaner shown in FIG. 1.

[0008] Figure 3 is a diagram showing an example of a method for forming a magnet by a compression molding method.

[0009] FIG. 4 is a schematic diagram of a magnet according to one embodiment of the present disclosure.

[0010] Figure 5a shows an example in which a magnet is divided into multiple parts for measuring compression density.

[0011] Figure 5b is a graph showing the results of measuring the compression density of the magnet illustrated in Figure 5a.

[0012] The various embodiments of this document and the terms used therein are not intended to limit the technical features described in this document to specific embodiments, and should be understood to include various modifications, equivalents, or substitutions of said embodiments.

[0013] In relation to the description of the drawings, similar reference numerals may be used for similar or related components.

[0014] The singular form of the noun corresponding to the item may include one or multiple items, unless the relevant context clearly indicates otherwise.

[0015] In this document, each of the phrases such as "A or B", "at least one of A and B", "at least one of A or B", "A, B or C", "at least one of A, B and C", and "at least one of A, B, or C" may include any one of the items listed together in the corresponding phrase, or all possible combinations thereof.

[0016] The term "and / or" includes a combination of multiple related described components or any of the multiple related described components.

[0017] Terms such as "first," "second," or "first" or "second" may be used simply to distinguish a component from another component and do not limit the components in other aspects (e.g., importance or order).

[0018] Where any (e.g., 1st) component is referred to as "coupled" or "connected" to another (e.g., 2nd) component, with or without the terms "functionally" or "communicationly," it means that said any component may be connected to said other component directly (e.g., via a wire), wirelessly, or through a third component.

[0019] Terms such as "include" or "have" are intended to specify the existence of the features, numbers, steps, actions, components, parts, or combinations thereof described in this document, and do not preclude the existence or addition of one or more other features, numbers, steps, actions, components, parts, or combinations thereof.

[0020] When it is said that a component is "connected," "combined," "supported," or "in contact" with another component, this includes not only cases where the components are directly connected, combined, supported, or in contact, but also cases where they are indirectly connected, combined, supported, or in contact through a third component.

[0021] When it is said that a component is located "on" another component, this includes not only cases where one component is in contact with the other, but also cases where another component exists between the two components.

[0022] Electronic products include electric motors. For example, a vacuum cleaner is equipped with a motor (electric motor) that generates suction force to suck in air containing foreign matter from a surface to be cleaned by rotating a fan. The motor may have a rotor and a stator. As an example, the rotor may have a magnet (permanent magnet), and the stator may have windings. When current flows through the windings, the rotor rotates due to electromagnetic interaction between the windings and the magnet.

[0023] Magnets can be manufactured by compression molding magnetic powder. In the case of permanent magnets manufactured by the compression molding method, the compression density in the center of the magnet is lower than that at both ends relative to the compression direction. Consequently, the magnetic force in the center of the magnet may be weaker compared to the ends relative to the compression direction. If such a magnet is applied to a motor rotor, it may be difficult to obtain the desired motor output due to the weak magnetic force, and more current may be consumed to achieve the desired output.

[0024] The present disclosure provides a magnet capable of suppressing the weakening of magnetic force in the central part compared to the ends with respect to the compression direction. The present disclosure provides an electric motor and a vacuum cleaner employing the aforementioned magnet. However, the technical problems to be solved in this document are not limited to those mentioned above, and other unmentioned technical problems will be clearly understood by those skilled in the art to which the present disclosure belongs from the description below.

[0025] Embodiments of the magnet and an electric motor and a vacuum cleaner employing the same according to the present disclosure are described below in detail so that those skilled in the art can easily implement the present invention. However, the present invention may be embodied in various different forms and is not limited to the embodiments described herein. Furthermore, in order to clearly explain the present invention in the drawings, parts unrelated to the explanation have been omitted, and similar parts throughout the specification are denoted by similar reference numerals.

[0026] FIG. 1 is a schematic diagram of a vacuum cleaner according to one embodiment of the present disclosure. The vacuum cleaner shown in FIG. 1 is a stick-type vacuum cleaner and is referred to simply as the vacuum cleaner (1) below. The vacuum cleaner (1) may be of a cordless type. However, it is not limited thereto, and the present disclosure may also be applied to a handheld vacuum cleaner or a robot vacuum cleaner. Referring to FIG. 1, the vacuum cleaner (1) according to one embodiment of the present disclosure may be a cordless vacuum cleaner that has a built-in rechargeable battery (6) and does not require a power cord to be connected to an outlet during cleaning. The vacuum cleaner (1) according to one embodiment of the present disclosure may include a main body (3), a brush device (2a), and an extension tube (2). However, not all components shown in FIG. 1 are essential components. The vacuum cleaner (1) may be implemented with more components than those shown in FIG. 1, or with fewer components. For example, the vacuum cleaner (1) may be implemented with a main body (3) and a brush device (2a), excluding the extension tube (2). Additionally, the vacuum cleaner (1) may further include a station (not shown) for dust discharge of the main body (3) and charging of the battery (6).

[0027] The main body (3) may include a suction fan (10) that forms a vacuum inside the vacuum cleaner (1), a dust collection container (dust container) (4) that receives foreign matter sucked from a surface to be cleaned (e.g., floor, bedding, sofa, etc.), and may include a handle (5) for a user to hold and move the vacuum cleaner (1) during cleaning.

[0028] The main body (3) may include a mounting portion to which an extension tube (2) or a brush device (2a) is mounted. The extension tube (2) may be formed as a hollow pipe. The extension tube (2) may have a certain rigidity. Additionally, the extension tube (2) may be formed as a flexible hose. A brush device (2a) may be detachably connected to one end of the extension tube (2). The other end of the extension tube (2) may be detachably connected to the extension tube mounting portion of the main body (3). Through the extension tube (2), the suction force generated by the suction fan (10) of the main body (3) may be transmitted to the brush device (2a), and air and foreign matter sucked in through the brush device (2a) may be moved to the main body (3). The extension tube (2) may be formed in multiple stages between the main body (3) and the brush device (2a). There may be two or more extension tubes (2).

[0029] The brush device (2a) is a device that comes into close contact with the surface to be cleaned and sucks up air and foreign matter from the surface to be cleaned. The brush device (2a) may be represented as a vacuum cleaner head. The brush device (2a) may be rotatably coupled to the extension tube (2). The types of the brush device (2a) may vary. For example, depending on the application, the brush device (2a) may include a general brush (floor brush), a carpet brush, a bedding brush, a pet brush, a mop brush, a multi-purpose brush (a brush usable on both carpets and floors), but is not limited thereto.

[0030] According to one embodiment of the present disclosure, the main body (3), the brush device (2a), and the extension tube (2) may each include a power line (e.g., a + power line, a - power line) and a signal line. The power line may be a line for transmitting power supplied from a battery (6) to the main body (3) and, if necessary, to the brush device (2a) connected to the main body (3). The signal line may be different from the power line and may be a line for transmitting and receiving signals between the main body (3) and the brush device (2a). The signal line may be implemented to be connected to the power line within the brush device (2a).

[0031] The main body (3) may include a suction power generating device (hereinafter referred to as a suction fan (10)) that generates the suction power necessary to suck up foreign substances on the surface to be cleaned, a dust collection container (4, also referred to as a dust container) in which foreign substances sucked up from the surface to be cleaned are received, an exhaust unit (7), a filter unit (71), and a battery (6) capable of supplying power to the suction fan (10). Although not shown in the drawing, the main body (3) may further include a communication interface, a user interface, a main processor, and memory.

[0032] The suction fan (10) may include a fan motor (electric motor) (11) that converts electric power into mechanical rotational power, an impeller (12) that rotates connected to the fan motor (11), and a printed circuit board (13) connected to the fan motor (11). By rotating the impeller (12) by the fan motor (11), a vacuum can be created inside the vacuum cleaner (1). Here, vacuum means a state lower than atmospheric pressure. The fan motor (11) may include a brushless motor, but is not limited thereto. The printed circuit board (13) may include various electrical and electronic components for controlling the fan motor (11). The suction fan (10) may have an inverted motor structure in which the positions of the impeller (12) and the printed circuit board (13) are reversed. In the inverted motor structure, the printed circuit board (13) may be located upstream of the fan motor (11) and the impeller (12) may be located downstream of the fan motor (11) based on the direction of air flow. Therefore, the impeller (12) may be closer to the filter section (71) than the printed circuit board (13). The suction fan (10) may be positioned across the dust collection container (dust container, 4) and the exhaust section (7). The suction fan (10) will be described in detail later.

[0033] The dust collection container (4) may be configured to filter and collect dust or dirt from the air entering through the brush device (2a). The dust collection container (4) may be provided to be detachable from the main body (3). The dust collection container (4) may collect foreign matter using a cyclone method that separates foreign matter using centrifugal force. Air from which foreign matter has been removed through the cyclone method may be discharged to the outside of the main body (3), and the foreign matter may be stored in the dust collection container (4). A multi-cyclone may be placed inside the dust collection container (4). The dust collection container (4) may be provided so that foreign matter is collected below the multi-cyclone. The dust collection container (4) may include a dust collection container door (also referred to as a cover of the dust collection container (4)) which is provided to open the dust collection container (4) when connected to a station not shown. The dust collector (4) may include a first dust collector where relatively large foreign substances are collected primarily and a second dust collector where relatively small foreign substances are collected by a multi-cyclone. Both the first dust collector and the second dust collector may be provided to be open to the outside when the dust collector door is opened.

[0034] Air passing through the dust collection container (4) flows into the exhaust section (7). The exhaust section (7) may be, for example, a hollow cylindrical shape, and may be provided with inner exhaust holes (7a) through which air is discharged on the outer circumference. For example, a filter section (71) may be arranged to surround the exhaust section (7). The filter section (71) may include a filter (72). The filter (72) may be, for example, cylindrical. The filter (72) may be arranged to surround the outer circumference of the exhaust section (7). A plurality of outer exhaust holes (73) may be formed in the case of the main body (3) that forms the outer circumference boundary of the filter section (71). The filter section (71) may include a filter (72) that filters ultrafine dust, etc., that is not filtered out in the dust collection container (4). The filter (72) may include a motor filter, a HEPA filter, etc., but is not limited thereto. Air flows from the exhaust section (7) to the filter section (71) through the inner exhaust port (7a), and after passing through the filter (72), is discharged to the outside of the vacuum cleaner (1) through the outer exhaust port (73).

[0035] The battery (6) can be detachably mounted on the main body (3). The battery (6) may be represented as a battery pack or a battery module. The battery (6) can be electrically connected to a charging terminal provided in the station. The battery (6) can be charged by receiving power from the charging terminal. According to one embodiment, the battery (6) may include a processor (e.g., MICOM (Micro-Computer, Microprocessor Computer, Microprocessor Controller)) for controlling the voltage supplied to the main body (3) and communicating with the main processor. The battery (6) can perform data communication with the main processor. The battery (6) can periodically transmit information regarding the battery charge status, output voltage, etc., to the main processor.

[0036] The battery (6) may include an LED display to indicate the charging, discharging, or status of the battery. For example, the processor of the battery (6) may output red, orange, or yellow through the LED display according to the charging rate, and then output green through the LED display when charging is complete.

[0037] The communication interface may include a module for performing communication with an external device. For example, the main body (3) may perform communication with a station or server device through the communication interface. The communication interface may include a short-range communication unit and a long-range communication unit. The short-range wireless communication unit may include, but is not limited to, a Bluetooth communication unit, a BLE (Bluetooth Low Energy) communication unit, a Near Field Communication (NFC) unit, a WLAN (Wi-Fi) communication unit, a Zigbee communication unit, an Infrared Data Association (IrDA) communication unit, a WFD (Wi-Fi Direct) communication unit, an UWB (ultra wideband) communication unit, an Ant+ communication unit, etc. The long-range communication unit may be used for the main body (3) to communicate with a server device remotely. The long-range communication unit may include the Internet, a computer network (e.g., LAN or WAN), or a mobile communication unit. The mobile communication unit may include, but is not limited to, 3G modules, 4G modules, 5G modules, LTE modules, NB-IoT modules, LTE-M modules, etc.

[0038] A user interface may be provided on the handle (5) and / or the main body (3). The user interface may include an input interface and an output interface. The main body (3) may receive user input related to the operation of the vacuum cleaner (1) through the user interface and may output information related to the operation of the vacuum cleaner (1). The main body (3) may output information regarding the operation status (e.g., operation mode), information regarding the remaining battery (6), information regarding the docking status, information regarding the status of the dust collection container (4), information regarding the status of the dust bag, information regarding moisture inflow, information regarding foreign matter jamming in the brush device (2a), etc., through the user interface.

[0039] The input interface may include at least one of a motion input unit, a voice input unit (e.g., a microphone), or an operation input unit (e.g., a power button, a suction power adjustment button), but is not limited thereto. The output interface may include an LED (light-emitting diode) display, an LCD (liquid crystal display), a touch screen, a speaker, etc., but is not limited thereto.

[0040] The main body (3) may include at least one processor. The main body (3) may include one processor or multiple processors. For example, the main body (3) may include a main processor connected to a user interface and a processor connected to a fan motor. At least one processor can control the overall operation of the vacuum cleaner. For example, at least one processor can control the power consumption (suction strength, suction mode) of the fan motor (11), the drum RPM of the brush device (2a), the trip level of the brush device (2a), etc.

[0041] At least one processor according to the present disclosure may include at least one of a CPU (Central Processing Unit), a GPU (Graphics Processing Unit), an APU (Accelerated Processing Unit), a MIC (Many Integrated Core), a DSP (Digital Signal Processor), and an NPU (Neural Processing Unit). At least one processor may be implemented in the form of an integrated system-on-chip (SoC) including one or more electronic components. Each of at least one processor may be implemented as separate hardware (H / W). At least one processor may be represented as a MICOM (Micro-Computer, Microprocessor Computer, Microprocessor controller), an MPU (Micro Processor Unit), or an MCU (Micro Controller Unit).

[0042] At least one processor according to the present disclosure may be implemented as a single core processor or as a multicore processor.

[0043] Memory may store programs for processing and controlling at least one processor, and may also store input / output data. For example, the memory includes a pre-learned artificial intelligence (AI) model (e.g., Support Vector Machine (SVM) algorithm, etc.), status data of the fan motor (11), a measurement value of a pressure sensor measuring fluid pressure, status data of the battery (6), status data of the brush device (2a) (e.g., RPM of the drum), error occurrence data (failure history data), power consumption of the fan motor (11) corresponding to operating conditions, operation sequence of the fan motor (11) corresponding to the suction force generation pattern, type of brush device (2a) corresponding to the voltage value input through the signal line, constraint level by type of brush device (2a), PWM frequency by type of brush device (2a), average input voltage by type of brush device (2a), high load reference value (or low load reference value) by type of brush device (2a), information regarding pre-defined movement patterns (user gestures) corresponding to a plurality of control commands, information regarding moisture ingress into the main body (3), and a reference load value for distinguishing the condition of the surface to be cleaned (e.g., floor or carpet) (e.g. Multiple reference load values ​​corresponding to multiple suction power modes, etc., can be stored.

[0044] Memory may include external memory and internal memory. For example, memory may include at least one type of storage medium among flash memory type, hard disk type, multimedia card micro type, card type memory (e.g., SD or XD memory, etc.), RAM (Random Access Memory), SRAM (Static Random Access Memory), ROM (Read-Only Memory), EEPROM (Electrically Erasable Programmable Read-Only Memory), PROM (Programmable Read-Only Memory), magnetic memory, magnetic disk, and optical disk. Programs stored in memory may be classified into multiple modules according to their functions.

[0045] Referring again to FIG. 1, the suction fan (10) may include a fan motor (11) and an impeller (12) that is rotated by the fan motor (11). The impeller (12) is placed in the main body (3) and rotates to generate the suction force necessary to suck up foreign matter on the surface to be cleaned. The suction fan (10) may further include a shroud (14) in which an air passage is formed for air to flow inside. The impeller (12) generates a suction force to suck air from the dust collection container (4) into the main body (3) through the air passage. The suction fan (10) may further include a diffuser (15). The diffuser (15) is shown with the external shape on the left side and the cross-sectional shape on the right side with respect to the rotation axis (A). Foreign matter sucked from the surface to be cleaned is received in the dust collection container (4).

[0046] The shroud (14) covers the outer side of the furnace. The shroud (14) may be a cylindrical member with a concave center. Based on the direction of airflow, the shroud (14) may have an upstream large diameter section with a large inner diameter, a downstream large diameter section with a large inner diameter, and a small diameter section between the upstream large diameter section and the downstream large diameter section. The ends of the upstream large diameter section and the downstream large diameter section on the small diameter side have a shape in which the inner diameter gradually decreases toward the small diameter section.

[0047] The suction fan (10) can be housed inside the main body (3) such that a portion thereof is partially inserted into the exhaust section (7). The downstream large-diameter portion of the shroud (14) is positioned inside the exhaust section (7). The upstream large-diameter portion of the shroud (14) is positioned so as to be partially inserted inside the dust collection container (4) while its surroundings are covered by a filter case (4a) capable of removing dust from the air. The impeller (12) can be positioned within the downstream large-diameter portion of the shroud (14), adjacent to the small-diameter portion. The diffuser (15) can be positioned within the downstream large-diameter portion of the shroud (14), downstream of the impeller (12).

[0048] The fan motor (11) may include a rotor assembly (40) and a stator assembly (50). The rotor assembly (40) may include a rotating shaft (20) and a magnet (30) fixed to the rotating shaft (20). An impeller (12) is fixed to one end of the rotating shaft (20). The stator assembly (50) is positioned around the rotor assembly (40), for example, the magnet (30), with an air gap (Ga) in between. The stator assembly (50) includes a winding coil. The rotor assembly (40) is rotated by the magnetic force generated by current flowing through the winding coil.

[0049] FIG. 2 is a schematic diagram of a rotor assembly (40) of a fan motor (11) applied to one embodiment of the vacuum cleaner (1) illustrated in FIG. 1. Referring to FIG. 2, the rotor assembly (50) may include a rotating shaft (20) and a magnet (30). The magnet (30) may be fixed directly to the rotating shaft (20), for example, by an adhesive. In this embodiment, the magnet (30) is cylindrical in shape, but is not limited thereto. The magnet (30) may be formed by compression molding magnetic powder together with a binder.

[0050] FIG. 3 is a drawing showing an example of a method for forming a magnet by compression molding. Referring to FIG. 3, first, a compound mixed with magnetic powder and a binder is inserted into a die (90). Then, a magnet (30) is formed by compression molding the compound by pressing it from above with an upper punch (91) as indicated by arrow (A1) and from below with a lower punch (92) as indicated by arrow (A2).

[0051] In compression molding, compression molding can be performed while heating, or compression molding can be performed without heating followed by sintering. In any case, when compression molding is performed, the compression density of the central part of the magnet (30) with respect to the compression direction tends to be lower than the compression density of the ends of the magnet (30). In FIG. 3, the part with high compression density is shown as cross-hatching, and the part with low compression density is shown as diagonal hatching. This is because pressure is not transmitted uniformly to the compound inside the die (90) during the compression molding process, and pressure decreases particularly in the central part in the compression direction. Accordingly, the magnetic force of the central part of the magnet (30) decreases, and the performance of the magnet (30) may be degraded.

[0052] The present disclosure provides a magnet (30) capable of reducing or resolving such problems. FIG. 4 is a schematic diagram of a magnet according to one embodiment of the present disclosure. Referring to FIG. 4, when supplying a compound into a die (Fig. 3: 90) during a compression molding process, first, a compound containing a conventional magnetic powder is introduced into a portion corresponding to the lower portion (31b) of the magnet (30) after compression molding. Next, a compound containing a magnetic powder having a magnetic flux density higher than that of the conventional magnetic powder is introduced into a portion corresponding to the central portion (32) of the magnet (30) after compression molding. Next, a compound containing a conventional magnetic powder is introduced into a portion corresponding to the upper portion (31a) of the magnet (30) after compression molding. In other words, in the present embodiment, the magnetic flux density of the compound forming the central portion (32) of the magnet (30) is made higher than the magnetic flux density of the compound forming the upper portion (31a) and lower portion (31b) of the magnet (30). The compound is a mixture of magnetic powder and a binder as described above. The magnetic powder may include, for example, neodymium. Additionally, to increase the strength of the magnet (30), the magnetic powder may further include, for example, niobium.

[0053] Here, the upper portion (31a) is a portion that includes the upper end of the axial direction of the cylindrical magnet (30), and the lower portion (31b) is a portion that includes the lower end of the axial direction of the cylindrical magnet (30). The combined portion of the upper portion (31a) and the lower portion (31b) is called the two end portion (31). That is, the two end portion (31) is a portion that includes both ends of the axial direction of the cylindrical magnet (30). Also, the central portion (32) is a portion between the two end portions (31). Furthermore, in this embodiment, assuming a case where the cylindrical magnet (30) is formed by compression molding in the axial direction of the cylinder, the portion that includes both ends of the axial direction of the cylinder is named the two end portion (31), and the portion between the two end portions (31) is named the central portion (32), but this is not limited thereto. The 'axial direction of the cylinder' can be generalized to the compression direction during compression molding.

[0054] In the following, the compound forming the two end portions (31) is referred to as the "first compound," and its magnetic flux density is referred to as the "first magnetic flux density." The compound forming the central portion (32) is referred to as the "second compound," and its magnetic flux density is referred to as the "second magnetic flux density." Examples of methods to make the second magnetic flux density of the second compound higher than the first magnetic flux density of the first compound are described.

[0055] The average grain size of the magnetic powder included in the second compound can be made larger than the average grain size of the magnetic powder included in the first compound. The grain size of the magnetic powder contributes to the magnitude of the residual magnetic flux density. The larger the grain size, the higher the residual magnetic flux density and the lower the coercivity. Meanwhile, the more fine particles there are in the particle size distribution of the particles formed by the aggregation of grains, the higher the compressive density. Even if the compressive density increases, the residual magnetic flux density increases. The particle size distribution differs between the central part (32) and the two end parts (31), and many fine particles are distributed in the central part (32). This method can be realized, for example, by selecting a magnetic powder with an appropriate average grain size from among magnetic powders with a large average grain size and magnetic powders with a small average grain size.

[0056] The amount of binder included in the second compound can be made smaller than the amount of binder included in the first compound. In this case, since the proportion of magnetic powder in the second compound increases, the decrease in magnetic strength after molding can be compensated for.

[0057] The magnetic powder included in the second compound may contain a substance that increases magnetic flux density (first additive). The first additive may include, for example, aluminum, copper, cobalt, etc.

[0058] The magnetic powder included in the first compound may contain a substance (second additive) that increases coercivity. The second additive may include, for example, gallium or zirconium. The ends (31) of the magnet (30) tend to have high compressive density and high magnetic flux density, but they are also parts that are prone to demagnetization. By including, for example, gallium or zirconium in the ends (31), the demagnetization resistance can be increased.

[0059] In another aspect, the magnet (30) according to the present disclosure may include a first magnet, a second magnet, and a third magnet that are sequentially stacked. The first magnet has a first magnetic flux density. The second magnet has a second magnetic flux density higher than the first magnetic flux density. The third magnet has the same first magnetic flux density as the first magnet. For example, the first, second, and third magnets may be neodymium bonded magnets. In this case, the neodymium bonded magnet forming the second magnet may have a higher magnetic flux density than the neodymium bonded magnet forming the first magnet. The third magnet may be the same neodymium bonded magnet as the first magnet. The magnet (30) may be formed by arranging the first, second, and third magnets in the axial direction of a cylinder and integrally molding them with a mold.

[0060] By the above-described methods, the reduction in magnetic force of the central part (32) of the magnet (30) is suppressed, making it possible to increase the performance of the rotor assembly (40).

[0061] In order to effectively suppress the reduction of magnetic force of the magnet (30), the length of the central part (32) of the magnet (30), or the ratio of the length of the central part (32) to the total length in the axial direction of the magnet (30), may be examined. Since the central part (32) of the magnet (30) is a part with low compression density during compression molding, the length of the central part (32) can be determined by measuring the compression density along the axial direction of the magnet (30). FIG. 5a shows an example in which the magnet (30) is divided into multiple parts for measuring compression density. FIG. 5b is a graph showing the results of measuring the compression density of the magnet (30) illustrated in FIG. 5a.

[0062] Referring to FIG. 5a, the magnet (30) after compression molding is divided into five parts (300, 311, 312, 321, 322). In FIG. 5a, the scale shown below the magnet (30) indicates the positions of the multiple parts (300, 311, 312, 321, 322). Specifically, the axial length range of the entire magnet (30) is 0 [mm] to 20 [mm]. The position of part (312) is 3 [mm], the position of part (311) is 6.5 [mm], the position of part (300) is 10 [mm], the position of part (321) is 13.5 [mm], and the position of part (322) is 17 [mm].

[0063] The results of measuring the compressive density of each part (300, 311, 312, 321, 322) are shown in FIG. 5(b). Referring to FIG. 5b, it can be seen that in the range where the position is smaller than 10 [mm], the compressive density of part (312) is the highest, and the compressive density of part (311) is lower than that of part (312). Furthermore, it can be seen that the compressive density of part (300) is the lowest. In addition, in the range where the position is larger than 10 [mm], it can be seen that the compressive density decreases in the order of parts (322, 321, 300).

[0064] Based on the graph of FIG. 5b, it is possible to determine how much the minimum ratio of the length of the central part (32) to the axial length of the entire magnet (30) should be, that is, how much the minimum ratio to the axial length of the entire magnet (30) should be for introducing magnetic powder with high magnetic flux density.

[0065] As an example, 5.83 (g / cm³), where the compressive density is slightly higher than the minimum value. 3 Magnetic powder with high magnetic flux density can be introduced in the range where it is ) or less. The compressive density is 5.83 (g / cm³). 3 The range of lengths below ) is 9.75 [mm] to 10.75 [mm], and is approximately 5% (= (10.75 [mm] - 9.75 [mm]) / 20 [mm]) of the axial length of the entire magnet (30).

[0066] Based on the graph of FIG. 5b, it is possible to determine how much the maximum ratio of the length of the central part (32) to the axial length of the entire magnet (30) should be, that is, how much the maximum ratio to the axial length of the entire magnet (30) should be when introducing magnetic powder with high magnetic flux density.

[0067] As an example, the compressive density is 5.91 (g / cm³), which is the lower value of the compressive densities at both ends. 3 It may be sufficient to introduce magnetic powder with high magnetic flux density into the range where it is ) or less. 5.91 (g / cm³), which is the lower value of the compressive densities at both ends. 3 The range of lengths below ) is 6.5 [mm] to 16.5 [mm], and is approximately 50% of the total axial length of the magnet (30) (= (16.5 [mm] - 6.5 [mm]) / 20 [mm]).

[0068] In summary, the ratio of the axial length of the central part (32) to the axial length of the entire magnet (30) can be 5% to 50%.

[0069] Since the graph in FIG. 5b is asymmetrical, the ratio of the axial length of the central part (32) to the axial length of the entire magnet (30) can be determined to be 5% to 50%, but the position of the axial central part (32) of the magnet (30) is not specified. However, if the compression density is measured under ideal conditions, the graph in FIG. 5b will be symmetrical, so the axial central part (32) of the magnet (30) will have a symmetrical shape centered at the 10 [mm] position. Therefore, the minimum range of the central part (32) may be from a position 2.5% of the length of the magnet (30) to the left, based on the 10 [mm] position, to a position 2.5% of the length of the magnet (30) to the right. Additionally, the maximum range of the central part (32) may be from a position 25% of the length of the magnet (30) to the left, based on a position of 10 [mm], to a position 25% of the length of the magnet (30) to the right.

[0070] In the embodiments described above, the magnet (30) according to the present disclosure is used in a rotary motor, but is not limited thereto. The magnet (30) according to the present disclosure may also be used in electric motors other than rotary motors, such as vibration motors and linear motors.

[0071] A vacuum cleaner according to one aspect of the present disclosure comprises: a suction fan comprising a fan motor and an impeller that generates a suction force necessary to suck up foreign matter on a surface to be cleaned while being rotated by the fan motor; and a dust collection container that receives foreign matter sucked from the surface to be cleaned. The fan motor comprises: a rotor assembly comprising a rotating shaft and a magnet fixed to the rotating shaft; and a stator assembly spaced apart from the rotor assembly with an air gap. The magnet comprises two end portions comprising a first compound having a first magnetic flux density and a central portion between the two end portions comprising a second compound having a second magnetic flux density higher than the first magnetic flux density.

[0072] In one embodiment, the magnet is formed by compression molding, and the two ends and the central portion may be arranged in the compression direction.

[0073] As one embodiment, the length of the central portion may be 5% to 50% of the total length of the magnet.

[0074] In one embodiment, the first and second compounds may include neodymium.

[0075] As one embodiment, the first and second compounds may further include niobium.

[0076] In one embodiment, the average grain size of the magnetic powder included in the second compound may be larger than the average grain size of the magnetic powder included in the first compound.

[0077] In one embodiment, the amount of binder included in the second compound may be less than the amount of binder included in the first compound.

[0078] As one embodiment, the second compound may include a first additive that increases magnetic flux density.

[0079] In one embodiment, the first additive may include at least one of aluminum, copper, and cobalt.

[0080] In one embodiment, the first compound may include a second additive that increases coercivity.

[0081] In one embodiment, the second additive may include at least one of gallium and zirconium.

[0082] An electric motor according to one aspect of the present disclosure comprises: a rotor assembly including a rotating shaft and a magnet fixed to the rotating shaft; and a stator assembly spaced apart from the rotor assembly with an air gap, wherein the magnet comprises two ends including a first compound having a first magnetic flux density and a central portion between the two ends including a second compound having a second magnetic flux density higher than the first magnetic flux density.

[0083] In one embodiment, the magnet is formed by compression molding, and the two ends and the central portion may be arranged in the compression direction.

[0084] As one embodiment, the length of the central portion may be 5% to 50% of the total length of the magnet.

[0085] A magnet according to one aspect of the present disclosure is a magnet formed by compression molding a compound comprising magnetic powder and a binder, comprising: two ends in the compression direction; and a central portion between the two ends. The compound at the two ends comprises a first compound having a first magnetic flux density, and the compound at the central portion comprises a second compound having a second magnetic flux density higher than the first magnetic flux density.

[0086] According to the magnet described above, the reduction in magnetic force in the central part of the magnet's compression direction can be suppressed. According to the electric motor employing the magnet described above, an electric motor having improved output can be realized by suppressing the reduction in magnetic force. According to the vacuum cleaner employing the electric motor described above, a high-performance vacuum cleaner can be realized. The technical effects intended to be achieved in this document are not limited to the technical effects mentioned above, and other technical effects not mentioned will be clearly understood by those skilled in the art to which this disclosure belongs from the description in this document.

[0087] As described above, although the magnet, electric motor, and vacuum cleaner of the present disclosure have been explained by limited embodiments and drawings, the present disclosure is not limited to the above embodiments and various modifications are possible within the scope without departing from the spirit thereof.

Claims

1. A suction fan (10) comprising a fan motor (11) and an impeller (12) that is rotated by the fan motor and generates the suction force necessary to suck up foreign substances on the surface to be cleaned; It includes a dust collection container (4) that receives foreign substances sucked from the surface to be cleaned, and The above fan motor (11) is, A rotor assembly (40) comprising a rotating shaft (20) and a magnet (30) fixed to the rotating shaft; It includes a stator assembly (50) spaced apart from the rotor assembly with an air gap around it, and The above magnet (30) is a vacuum cleaner comprising two end portions (31) having a first compound having a first magnetic flux density and a central portion (32) between the two end portions having a second compound having a second magnetic flux density higher than the first magnetic flux density.

2. In Paragraph 1, The above magnet is formed by compression molding, A vacuum cleaner in which the above-mentioned two ends and the above-mentioned central portion are arranged in a compression direction.

3. In Paragraph 1 or 2, A vacuum cleaner in which the length of the central portion is 5% to 50% of the total length of the magnet.

4. In any one of paragraphs 1 through 3, The above first and second compounds are a vacuum cleaner containing neodymium.

5. In Paragraph 4, The above first and second compounds are cleaners that further include niobium.

6. In any one of paragraphs 1 through 5, A vacuum cleaner in which the average grain size of the magnetic powder included in the second compound is larger than the average grain size of the magnetic powder included in the first compound.

7. In any one of paragraphs 1 through 5, A cleaner in which the amount of binder included in the second compound is less than the amount of binder included in the first compound.

8. In any one of paragraphs 1 through 7, The above second compound is a vacuum cleaner containing a first additive that increases magnetic flux density.

9. In Paragraph 8, The first additive above is a cleaner comprising at least one of aluminum, copper, and cobalt.

10. In any one of paragraphs 1 through 9, The above first compound is a vacuum cleaner containing a second additive that increases coercivity.

11. In Paragraph 10, The above second additive is a cleaner comprising at least one of gallium and zirconium.

12. A rotor assembly (40) comprising a rotation axis (20) and a magnet (30) fixed to the rotation axis; It includes a stator assembly (50) spaced apart from the rotor assembly with an air gap around it, and The above magnet (30) is a motor comprising two end portions (31) having a first compound having a first magnetic flux density and a central portion (32) between the two end portions having a second compound having a second magnetic flux density higher than the first magnetic flux density.

13. In Paragraph 12, The above magnet is formed by compression molding, An electric motor in which the above-mentioned two ends and the above-mentioned central portion are arranged in a compression direction.

14. In Paragraph 12 or 13, An electric motor in which the length of the central portion is 5% to 50% of the total length of the magnet.

15. A magnet (30) formed by compression molding a compound containing magnetic powder and a binder, Both ends (31) in the compression direction; It includes a central portion (32) between the two ends (31) mentioned above, The compound at both ends above includes a first compound having a first magnetic flux density, The compound in the central portion above is a magnet comprising a second compound having a second magnetic flux density higher than the first magnetic flux density.

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