Blower device, heat source-side unit of refrigeration cycle device comprising said blower device, utilization-side unit of refrigeration cycle device, refrigeration cycle device, ventilation unit, and air cleaner

Abstract

[Problem] To provide a blower device with which poor oil film formation in a bearing can be prevented even at low-speed rotation so as to enable continuous operation over a long period, and to provide: a heat source-side unit comprising said blower device; a utilization-side unit; a refrigeration cycle device; a ventilation unit; and an air cleaner. [Solution] A blower device according to one embodiment of the present invention comprises: a motor that has a variable rotational speed and that includes a stator, a rotor disposed inside the stator, a shaft to which the rotor is fixed, and a bearing which rotatably supports the shaft; and a control unit that controls a rotational speed of the motor. The control unit has at least a rotation mode in which a rotational speed n [rpm] of the motor is set to a rotational speed satisfying 50 ≤ n < 100. The bearing includes an inner ring, an outer ring, a plurality of rolling bodies provided in an annular bearing space formed between the inner ring and the outer ring, and urea-based grease filled in the bearing space. The blower device can maintain the motor in the rotation mode for a time longer than 5 hours.

Description

[Addition based on Rule 26 03.04.2025] Blower, heat source side unit of refrigeration cycle device equipped with said blower, user side unit of refrigeration cycle device, refrigeration cycle device, ventilation unit, and air purifier

[0001] The present invention relates to a blower, a heat source unit of a refrigeration cycle device including the blower, a user unit of the refrigeration cycle device, a refrigeration cycle device, a ventilation unit, and an air purifier.

[0002] A blower that uses a motor to rotate an impeller is known. For example, Patent Document 1 describes a blower that includes a variable speed motor whose rotating shaft is supported by bearings filled with lubricant, and a control unit that drives the motor, and the control unit drives the motor at 300 rpm or more for 1 second to 2 minutes when the motor is continuously driven at 50 rpm or more but less than 300 rpm for 10 minutes to 5 hours.

[0003] Japanese Patent Application Laid-Open No. 2022-117021

[0004] In recent years, there has been a demand for a blower that can prevent poor oil film formation inside the bearing even at low rotation speeds and can operate continuously for long periods of time. However, in Patent Document 1, if the rotation speed is kept low for a long period of time, poor oil film formation occurs inside the bearing, so the rotation speed is switched to a high state to form an oil film inside the bearing, which is a problem in that it is difficult to operate the blower continuously for long periods of time at low rotation speeds.

[0005] In view of the above circumstances, the object of the present invention is to provide a blower that can prevent poor oil film formation inside bearings even at low rotation speeds and can operate continuously for long periods of time, as well as a heat source unit of a refrigeration cycle device that is equipped with the blower, a user unit of a refrigeration cycle device, a refrigeration cycle device, a ventilation unit, and an air purifier.

[0006] In order to achieve the above object, one form of the present invention provides a blower comprising a motor having a variable rotational speed, the motor having a stator, a rotor arranged inside the stator, a shaft to which the rotor is fixed, and a bearing that rotatably supports the shaft, and a control unit that controls the rotational speed of the motor, wherein the control unit has at least a rotation mode in which the rotational speed n [rpm] of the motor is set to a rotational speed that satisfies 50≦n<100, the bearing has an inner ring, an outer ring, and a plurality of rolling elements provided in an annular bearing space formed between the inner ring and the outer ring, and urea-based grease filled in the bearing space, and the blower is capable of maintaining the motor in the rotational mode for a period of time longer than 5 hours.

[0007] According to the above-described blower, the control unit has at least a rotation mode in which the rotation speed n [rpm] of the motor satisfies 50≦n<100, and the bearing has an inner ring, an outer ring, a plurality of rolling elements provided in an annular bearing space formed between the inner ring and the outer ring, and urea-based grease filled in the bearing space. In other words, by using urea-based grease in the bearing, it is possible to suppress the generation of abnormal bearing noise caused by low-speed rotation, even when the motor is operated for longer than five hours at a low rotation speed n [rpm] of 50≦n<100.

[0008] The blower may be capable of maintaining the rotation mode for a period of time greater than 24 hours.

[0009] The rotation speed n [rpm] of the motor in the rotation mode may satisfy 50≦n<80.

[0010] The urea-based grease contains a base oil, an additive, and a thickener, and the thickener contains a urea group. The base oil has a kinematic viscosity ν of 40 [mm ２ / s] or more.

[0011] The base oil has a kinematic viscosity ν of 80 [mm ２ / s] or more.

[0012] The motor may further include an impeller fixing portion on one end side of the shaft to which an impeller is attached.

[0013] The radial load on the bearing may be 10N or more.

[0014] The present invention may be a heat source side unit of a refrigeration cycle device, which includes the above-mentioned blower device.

[0015] The device may be a user-side unit of a refrigeration cycle device including the above-mentioned blower device.

[0016] The refrigeration cycle device may include at least one of the heat source side unit and the user side unit.

[0017] The present invention may be a ventilation unit including the above-described blower.

[0018] The present invention may be an air purifier including the above-mentioned blower device.

[0019] According to the present invention, it is possible to provide a blower that can prevent poor oil film formation inside bearings even at low rotation speeds and can operate continuously for long periods of time, as well as a heat source unit of a refrigeration cycle device that is equipped with the blower, a user unit of a refrigeration cycle device, a refrigeration cycle device, a ventilation unit, and an air purifier.

[0020] 1 is a cross-sectional view of a motor of a blower device according to an embodiment of the present invention; FIG. 2 is a view showing a bearing of the motor; FIG. 3 is a block diagram of the motor and control unit of the blower device; FIG. 4 is a view explaining the phenomenon in which abnormal noise is generated from the bearing, where (A) is a view showing a case in which the rolling elements rotate at high speed, and (B) is a view showing a case in which the rolling elements rotate at low speed; FIG. 5 is a view showing the generation of abnormal noise due to changes in the rotation speed of the motor; FIG. 6 is a view showing the relationship between the bearing and grease, where (A) shows the state before rotation and (B) shows the state during rotation; FIG. 7 is a view showing the relationship between the friction coefficient of the bearing and the state of lubrication; FIG. 8 is a conceptual diagram showing a refrigeration cycle device (air conditioner) equipped with a blower device of the present invention; FIG. 9 is a cross-sectional view of a main part of a heat source side unit (outdoor unit) of a refrigeration cycle device (air conditioner) equipped with a blower device of the present invention, viewed from the side; FIG. 10 is a cross-sectional view of an air purifier equipped with a blower device of the present invention; FIG. 11 is a conceptual diagram showing a ventilation unit equipped with a blower device of the present invention.

[0021] Next, an embodiment of the present invention will be described with reference to the drawings. In the following description of the drawings, the same or similar parts are denoted by the same or similar reference numerals. However, it should be noted that the drawings are schematic and may differ from the actual product. Therefore, specific components should be determined by taking the following description into consideration.

[0022] Furthermore, the embodiments shown below are merely examples of devices and methods for embodying the technical concept of the present invention, and the technical concept of the present invention does not limit the shape, structure, arrangement, etc. of the components to those described below. The technical concept of the present invention can be modified in various ways within the technical scope defined by the claims.

[0023] A blower F according to one embodiment of the present invention will be described below.

[0024] FIG. 1 is a cross-sectional view of a motor 1 of a blower F according to an embodiment of the present invention, and FIG. 2 is a diagram showing bearings (a first bearing 7 and a second bearing 8) of the motor 1. FIG. 3 is a block diagram of the motor 1 and a control unit 100 of the blower F. As shown in FIG. 1, the motor 1 is, for example, a brushless DC motor. In this embodiment, the motor 1 is used to rotate an impeller 300 of the blower F mounted in, for example, a refrigeration cycle device, particularly a heat source unit of the refrigeration cycle device (for example, an outdoor unit 210 of an air conditioner 200 described below).

[0025] 3, the blower F includes a control unit 100 and a blower (fan) 150. The blower (fan) 150 includes a motor 1 and an impeller 300 driven by the motor 1.

[0026] (Motor and blower) The motor 1 is an inverter motor with variable rotation speed that includes a stator 2, a rotor 3, a shaft 6, bearings (first bearing 7, second bearing 8), a bracket 4, a resin outer casing 10, and a circuit board 5.

[0027] (Rotor) The rotor 3 has an annular permanent magnet portion 31 and a rotor body 30. The rotor body 30 has an outer peripheral surface and an inner peripheral surface. The permanent magnet portion 31 is fixed to the outer peripheral surface of the rotor body 30. The rotating shaft 6 is fixed to the inner peripheral surface of the rotor body 30. As a result, the rotating shaft 6 is rotated integrally with the rotor body 30.

[0028] The rotor 3 is a surface magnet type with a ring-shaped permanent magnet portion 31 fixed to the outer circumferential surface. The permanent magnet portion 31 is formed in a ring shape by multiple (e.g., 8 or 10) permanent magnets so that north and south poles alternate at equal intervals around the circumference. The permanent magnet portion 31 is typically formed from a sintered metal such as an Nd—Fe—B alloy, but may also be formed from a ring-shaped plastic magnet made by solidifying magnetic powder with resin.

[0029] (Stator) The stator 2 includes a stator core 21 having a cylindrical yoke and multiple teeth extending radially inward from the yoke, and windings (coils) 22 wound around the teeth. The stator core 21 is a laminate of multiple plates made of a soft magnetic material such as electromagnetic steel sheets. The outer circumferential surface of the stator 2 (stator core 21) is covered with a resin outer casing 10 (see FIG. 1). The stator 2 is arranged such that the permanent magnet portion 31 of the rotor 3 faces the stator core 21 of the stator 2 in the radial direction via a gap (magnetic gap).

[0030] (Resin Outer Shell) The resin outer shell 10 is formed of an insulating resin material. As shown in FIG. 1 , the resin outer shell 10 is formed into a hollow cylindrical shape having an open end 10A at one end in the axial direction C (in this embodiment, the end opposite the output end 61 of the shaft 6). Here, the output end 61 is the end of the shaft 6 located on the load side (the end connected to the load) of the motor 1, and functions as an impeller fixing portion to which the impeller 300 (described later) is attached. As described above, the resin outer shell 10 is molded integrally with the stator 2. The resin material for forming the resin outer shell 10 is not particularly limited, and the resin outer shell 10 may be formed of, for example, BMC (Bulk Molding Compound: unsaturated polyester resin) resin.

[0031] The resin housing 10 also has a mounting surface 9. The mounting surface 9 is formed on the inner peripheral surface of the resin housing 10, is an inner peripheral plane perpendicular to the axial direction, and is provided axially on the opposite side of the output end 61 of the rotating shaft 6 from the rotor 3 via a gap. The mounting surface 9 supports a circuit board 5, which will be described later. The mounting surface 9 may be formed continuously in the circumferential direction on the inner peripheral surface of the resin housing 10, or may be formed at multiple locations spaced apart in the circumferential direction.

[0032] The resin housing 10 further includes a second bearing accommodating portion 10C that accommodates a second bearing 8 (described later). The second bearing accommodating portion 10C has a generally cylindrical shape with one end closed and centered on the axis C. The second bearing accommodating portion 10C is provided on a bottom portion 10B of the resin housing 10, on the side opposite to the open end portion 10A.

[0033] (Circuit Board) The circuit board 5 includes a wiring board and electronic components that generate heat when energized and are mounted on the surface of the wiring board (the surface opposite the output end 61 of the rotating shaft 6). The circuit board 5 is generally disk-shaped, and the peripheral edge of the circuit board 5 is supported on the mounting surface 9 and fixed thereto by, for example, adhesion, bonding, screw fastening, soldering, or the like.

[0034] The electronic components that generate heat when energized are primarily semiconductor components such as power supply ICs and ICs for controlling motor drive current, but may also include passive components such as capacitors. In addition to the electronic components, the wiring board also carries other components, such as connectors connected to a power cable, but these are not shown. The power cable is connected to a power source (not shown) through a cable insertion hole formed in the vicinity of the open end 10A of the resin housing 10 over a predetermined angular range in the circumferential direction.

[0035] (Bracket) The bracket 4 has a first bearing accommodating portion 41 and a disk portion 42. The heat sink 4 is attached and fixed to the open end portion 10A of the resin outer shell 10. The heat sink 4 is made of a metal material with excellent thermal conductivity, such as aluminum. The heat sink 4 is molded, for example, by die casting.

[0036] The heat sink 4 functions as a lid member (bracket) that covers the open end 10A of the resin outer shell 10 and thereby closes the opening of the resin outer shell 10. The heat sink 4 is fixed to the open end 10A of the resin outer shell 10 using a plurality of screw members (not shown).

[0037] 2, the first bearing 7 is formed in a generally circular ring shape. The first bearing 7 is a ball bearing having an outer ring 71, an inner ring 72, a cage 73, rolling elements (balls) 74, and grease G. The second bearing 8 is a ball bearing having an outer ring 81, an inner ring 82, a cage 83, rolling elements 84, and grease G.

[0038] As shown in FIG. 2 , the outer ring 71 of the first bearing 7 is annular and fixed to the bracket 4 (first bearing accommodating portion 41). The inner ring 72 of the first bearing 7 is annular and fixed to the opposite side of the output end 61 of the rotating shaft 6. Furthermore, a plurality of rolling elements 74 of the first bearing 7 are provided in a bearing space W1, which is an annular space formed between the inner ring 72 and the outer ring 71. A cage 73 is provided in the bearing space W1 and holds the rolling elements 74 so that they can roll freely. Furthermore, the cage 73 holds the plurality of rolling elements 74 at regular intervals around the circumferential direction of the first bearing 7. Grease G is a semi-solid lubricant containing a base oil, an additive, and a thickener, and is filled into the bearing space W1.

[0039] The outer ring 81 of the second bearing 8 is formed in an annular shape and is fixed to the resin outer shell 10 (second bearing accommodating portion 10C), and the inner ring 82 of the second bearing 8 is fixed to the output end portion 61 of the rotating shaft 6. Furthermore, a plurality of rolling elements 84 of the second bearing 8 are provided in a bearing space W2, which is an annular space formed between the inner ring 82 and the outer ring 81. A cage 83 is provided in the bearing space W2 and holds the rolling elements 84 so that they can roll freely. The cage 83 also holds the plurality of rolling elements 84 at regular intervals around the circumferential direction of the second bearing 8. Grease G is a semi-solid lubricant containing a base oil, additives, and a thickener, and is filled into the bearing space W2. In the embodiment, urea grease is used as the grease G.

[0040] When pressure is applied from the outside, the base oil in the grease G becomes fluid due to shear force, and the grease G functions as the lubricant described above. In other words, as the rolling elements 74 rotate, pressure is applied to the grease G, causing the base oil to seep out of the grease G, forming an oil film between the outer rings 71, 81 and the inner rings 72, 82 and the rolling elements 74. This allows the rolling elements 74 to rotate smoothly.

[0041] The urea grease used as grease G in the examples is a grease containing a urea compound having a urea group (-NHCONH-) in the molecule as a thickener. The urea compound used as the thickener is preferably a diurea having two urea groups in the molecule, but may also be a compound having three or more urea groups (e.g., triurea or tetraurea). Furthermore, although an aliphatic diurea is used as the diurea in the examples, an aromatic diurea may also be used. Because urea grease does not contain a metal group in the thickener molecule, it is characterized by its long life even at high temperatures and its lack of deterioration due to oxidation of the base oil.

[0042] The urea grease of the present embodiment contains 5 to 30% by weight of a urea compound and 95 to 70% by weight of a base oil relative to the total weight of the grease, but is not limited to this. One known method for producing a urea compound is to obtain diurea by reacting a diisocyanate compound, which is also a raw material for polyurethane, with an amine compound.

[0043] The rotating shaft 6 is supported by a first bearing 7 and a second bearing 8 so as to be rotatable about the axis C relative to the bracket 4 and the resin outer shell 10 .

[0044] In this embodiment, the grease G contains either a first urea grease G1 or a second urea grease G2 as a urea grease. The first urea grease G1 contains a base oil whose main component is synthetic hydrocarbon, and whose kinematic viscosity ν at 40° C. is 48 [mm ２ / s], and the thickener is a urea grease containing a urea compound. The second urea grease G2 has an ester oil as the main component of the base oil, and the kinematic viscosity ν of the base oil at 40°C is 100 [mm ２ / s], and the thickener is a urea grease containing a urea compound.

[0045] As shown in FIG. 1 and FIG. 9 described later, the impeller 300A is fixed to the output end 61 (impeller fixing portion) of the shaft 6, and rotates in synchronization with the rotation of the rotary shaft 6.

[0046] (Control Unit) The control unit 100 includes a computer having a processor such as a CPU and memory devices such as a ROM and a RAM. The control unit 100 includes an inverter circuit that controls the rotation speed of the motor 1 by controlling the frequency of the pulse voltage supplied to the motor 1. The control unit 100 outputs a control signal for controlling the frequency of the pulse voltage to the motor 1 via a signal line. In other words, the control unit 100 can control the rotation speed of the motor 1 using the control signal.

[0047] The control unit 100 has a low-speed rotation mode (rotation mode, first rotation mode) in which the motor 1 rotates at a low speed, and a high-speed rotation mode (second rotation mode) in which the motor 1 rotates at a high speed. The control unit 100 controls the rotation speed of the motor 1 in the low-speed rotation mode or the high-speed rotation mode.

[0048] The low-speed rotation mode is a rotation mode in which the rotation speed n [rpm] of motor 1 is a rotation speed that satisfies 50≦n<100, and the high-speed rotation mode is a rotation mode in which the rotation speed n [rpm] of motor 1 is a rotation speed that satisfies 100≦n.

[0049] That is, the control unit 100 rotates the motor 1 at a rotation speed n [rpm] where 50≦n<100, causing the motor 1 to rotate in the low-speed rotation mode. The control unit 100 also rotates the motor 1 at a rotation speed n [rpm] where 100≦n, causing the motor 1 to rotate in the high-speed rotation mode.

[0050] 4A and 4B are diagrams illustrating the phenomenon in which abnormal noise is generated from the bearing (first bearing 7), where (A) shows the case in which the rolling element 74 rotates at high speed, and (B) shows the case in which the rolling element 74 rotates at low speed. The arrows in Fig. 4 indicate the direction of rotation of the rolling element.

[0051] As shown in Figure 4, base oil seeps out of grease G when pressure is applied by the rotating rolling element 74. As shown in Figure 4(A) , during high-speed rotation (rotational speed n [rpm] is 100≦n), the pressure applied to grease G is large. Therefore, the base oil seeping out of grease G forms an oil film of sufficient thickness between the rolling element 74 and the outer ring 71, allowing the rolling element 74 to rotate smoothly.

[0052] On the other hand, as shown in Figure 4(B), when the rotational speed is low (rotational speed n [rpm] is 50≦n<100), the pressure on the grease G is small. As a result, little base oil seeps out of the grease G, and a problem occurs in that an oil film of sufficient thickness is not formed between the rolling elements 74 and the outer ring 71, causing the oil film to break down. In other words, when the rotational speed is continuously low for a long period of time, the oil film breaks down between the rolling elements 74 and the outer ring 71 (metal contact) for a long period of time, which may lead to the generation of abnormal noise or damage to the bearing.

[0053] 4, the relationship between the rolling elements 74 and the outer ring 71 has been described, but of course this is not limited to this, and the above-described problem also occurs between the rolling elements 74 and the inner ring 72. Furthermore, the above-described problem is not limited to the first bearing 7, but also occurs with the second bearing 8.

[0054] Here, Fig. 5 shows whether or not abnormal noise occurs depending on the rotation speed of the motor 1 when the motor 1 is driven continuously for a long period of time. Fig. 6 shows the internal state of the bearing 7 when grease G, which is urea grease, is used, with Fig. 6(A) showing the state before rotation and Fig. 6(B) showing the state during rotation. Fig. 7 shows the relationship between the friction coefficient of the bearing and the state of lubrication.

[0055] The lithium-based grease shown in Fig. 5 refers to the lithium grease used as a comparative example. The lithium grease is a semi-solid lubricant containing a base oil, an additive, and a thickener, and refers to lithium soap grease in which lithium soap is used as the thickener. Specifically, the lithium soap grease used as a comparative example has an ester oil as the main component of the base oil, and the kinematic viscosity ν of the base oil at 40°C is 26 [mm ２ / s] was used.

[0056] In FIG. 5 , a vibration noise analysis system (manufacturer: Bruel & Kjar, software: PULS, front end: Type 3160-A-042) was used to measure noise while rotating electric motor 1 using blower F (see FIG. 9 , described below). Here, the mass of impeller 300 (propeller fan) is approximately 1.5 kg, the axial loads on bearings 7 and 8 in FIG. 1 are both approximately 41 N, the radial load on bearing 7 is approximately 21 N, and the radial load on bearing 8 is approximately 36 N. The vertical axis represents the noise OA (overall) value [dB(A)], and the horizontal axis represents the time [h] during continuous rotation of motor 1. The "lithium-based" grease in the legend of FIG. 5 indicates the case where the aforementioned lithium grease was used. The experiment was conducted with a fixed rotation speed of 150 rpm during continuous rotation. Furthermore, the "urea-based" in the legend indicates the case where the second urea grease described above was used as the grease, and experiments were conducted with the rotation speed during continuous rotation fixed at 150 [rpm], 100 [rpm], and 50 [rpm]. Table 1 below shows whether or not there was any acoustic deterioration when a motor using lithium grease and a motor using the second urea grease were continuously rotated for 10,000 hours, and the rotation speed [rpm] of the motor during continuous rotation at that time. In Table 1, "x" indicates that acoustic deterioration occurred under that condition (an increase in noise occurred), and "o" indicates that there was no acoustic deterioration under that condition (no increase in noise occurred).

[0057]

[0058] As shown in Figure 5 and Table 1, with the lithium-based (lithium grease), when the rotation speed was 150 rpm, the noise OA value gradually increased once the continuous rotation time exceeded 1,000 hours, and at 2,200 hours, the noise OA value increased by approximately 6 dB (A) (deterioration in acoustics). On the other hand, with the second urea grease, no increase in the noise OA value (deterioration in acoustics) with increasing continuous rotation time was observed, as with the lithium-based grease, regardless of whether the rotation speed was 200, 150, 100, or 50 rpm and the grease was operated continuously for 10,000 hours.

[0059] Here, we will consider the reasons for the results shown in Figure 5 and Table 1. The parameter Λ is a measure of the degree of metal-to-metal contact, and is calculated as Λ = oil film thickness (e.g., the thickness of the oil film formed between the outer ring 71 and the rolling elements 74) [mm] ÷ surface roughness (e.g., the surface roughness of the outer ring 71 or the rolling elements 74) [mm]. Generally, when Λ < 1, boundary lubrication occurs (a lubrication state in which metal-to-metal contact occurs locally). When 1 < Λ < 3, mixed lubrication occurs (a state in which boundary lubrication and fluid lubrication coexist). Furthermore, when 3 < Λ, fluid lubrication occurs (a lubrication state in which two surfaces (e.g., the outer ring 71 and the rolling elements 74) are completely separated by a fluid film).

[0060] When the lithium-based lubricant (lithium grease) was used and the rotation speed was 150 rpm for 2200 hours, the noise OA value increased by 6 dB compared to immediately after the start of continuous rotation. This suggests that boundary lubrication occurs when the noise OA value begins to increase, i.e., when the continuous rotation time exceeds 1000 hours, and the parameter Λ at this time is estimated to be Λ<1.

[0061] On the other hand, with the urea-based grease (second urea grease G2), the noise OA value when continuously rotated for 10,000 hours at a rotation speed of 150 rpm was equivalent to the noise OA value immediately after (0 hour) the start of continuous rotation at 150 rpm. Furthermore, the noise OA value when continuously rotated for 10,000 hours at a rotation speed of 50 rpm was equivalent to the noise OA value immediately after (0 hour) the start of continuous rotation at 50 rpm. Furthermore, the noise OA value when continuously rotated at a rotation speed of 50 rpm was equivalent to the noise OA value when continuously rotated at a rotation speed of 150 rpm. In other words, with the urea-based grease, when continuously rotated at a rotation speed in the range of 50 to 150 rpm, there was no increase in noise even as the continuous rotation time increased. In this case, the parameter Λ was in the range of 1<Λ<3, so that temporary metallic contact should have continued for a long time, but as shown in Figure 5, there was no increase in noise as the continuous rotation time increased. From this, it is believed that when a urea-based grease (second urea grease G2) is used as the grease, metallic contact can be suppressed even if the parameter Λ is in the range of 1<Λ<3.

[0062] When lithium-based grease (lithium grease) is used as the grease, the change that occurs in the composition of the thickener contained in the lithium grease due to frictional heat associated with the rotation of the rolling elements 74 is primarily oxidation. However, when urea-based grease (first urea grease G1, second urea grease G2) is used as the grease, the change that occurs in the composition of the thickener in the urea grease due to frictional heat associated with the rotation of the rolling elements 74 is not only oxidation but also hardening.

[0063] As shown in FIG. 6 , hardening of grease G refers to the phenomenon in which a urea component (urea compound) U adhering to a metal surface oxidizes to form a film on the metal surface. More specifically, the urea group (—NHCONH—) contained in the urea grease adhering to the metal surface oxidizes and converts to a carboxylic acid (—NHCOOH), thereby protecting the metal surface with a carboxylic acid film. In this embodiment, the oxidized urea component U of grease G adheres to the rolling elements 74, outer ring 71, and inner ring 72 (the oxidized urea component U also adheres to the outer ring 81 and inner ring 82 in the same manner as to the outer ring 71 and inner ring 72). In other words, because the metal surfaces (rolling elements 74, outer ring 71, and inner ring 72) are protected by the oxidized urea component U (carboxylic acid), direct contact (metal contact) between the rolling elements 74 and the outer ring 71 (or inner ring 72, or the outer ring 81 and inner ring 82) can be suppressed, even when the rolling elements 74 rotate at low speeds.

[0064] Therefore, even if the state is in either the boundary lubrication region (Λ<1) or the mixed lubrication region (1<Λ<3), it is presumed that by using a urea-based grease (urea grease) as in this embodiment, the film of urea component U adhering to the metal surface can suppress direct metal-to-metal contact. In this way, by using a urea-based grease (first urea grease G1, second urea grease G2) as the grease, it is possible to suppress the generation of abnormal noise due to metal-to-metal contact, even when the motor 1 is operated continuously at low speed for long periods of time. Furthermore, suppressing metal-to-metal contact within the bearing can suppress damage to the bearing.

[0065] Fig. 7 is a conceptual diagram showing a Stribeck curve. As shown in Fig. 7, the vertical axis represents the friction coefficient within the bearing (for example, the friction coefficient between the outer ring 71 and the rolling element 74), and the horizontal axis represents the bearing constant, which changes depending on the viscosity of the grease, the rotational speed, and the load.

[0066] As shown in Figure 7, in the boundary lubrication region (Λ<1) and the mixed lubrication region (1<Λ<3), the higher the viscosity of the grease, the lower the friction coefficient. It can also be seen that the lower the rotational speed [rpm], the higher the friction coefficient, and the greater the load on the motor 1. In other words, even at the same rotational speed and load, the kinematic viscosity of the base oils of the first urea grease and the second urea grease is higher than the kinematic viscosity of the base oil of the lithium grease, so the coefficient of friction is lower when urea grease is used than when lithium grease is used. In other words, by using urea grease, it is possible to operate continuously for long periods of time even at lower rotational speeds than when lithium grease is used.

[0067] In this embodiment, the configuration of the blower F allows the motor 1 to be continuously operated (maintained) for a period of time longer than 5 hours in the low-speed rotation mode. Furthermore, in this embodiment, the blower F allows the motor 1 to be continuously operated (maintained) for a period of time longer than 24 hours in the low-speed rotation mode, so that the blower F can be operated all day long.

[0068] In this embodiment, the motor 1 is described as an inner rotor brushless DC motor in which a cylindrical rotor 3 having a permanent magnet portion is rotatably disposed radially inside a cylindrical stator 2 that generates a rotating magnetic field. However, the motor 1 is not limited to this, and may be, for example, an outer rotor brushless DC motor, an AC motor, or another type of motor.

[0069] 8 is a refrigerant circuit diagram showing a refrigeration cycle device equipped with a blower F of the present invention. The refrigeration cycle device is applied to an air conditioner 200 that cools and heats a room. The air conditioner 2000 includes an outdoor unit 210 and an indoor unit 270. The outdoor unit 210 includes a compressor 230, a four-way valve 240, an outdoor heat exchanger 250, an expansion valve (pressure reducing device) 260, and an outdoor unit control unit 100A.

[0070] The compressor 230 has a discharge port 231 as a discharge portion and a suction port 232 as a suction portion. The compressor 230 is controlled by the outdoor unit control unit 100A to compress the refrigerant supplied from the suction port 232 via a suction pipe 233 and a four-way valve 240, and supplies the compressed refrigerant from the discharge port 231 to the four-way valve 240 via a discharge pipe 234.

[0071] The four-way valve 240 is connected to the discharge pipe 234 and the suction pipe 233, and is also connected to the outdoor heat exchanger 250 via refrigerant piping 410 and to the indoor unit 270 via refrigerant piping 420. The indoor unit 270 and the outdoor heat exchanger 250 are connected via refrigerant piping 430. The four-way valve 240 switches the air conditioning apparatus 200 to either the heating mode or the cooling mode under the control of the outdoor unit control unit 100A. When switched to the cooling mode, the four-way valve 240 supplies the refrigerant discharged from the compressor 230 to the outdoor heat exchanger 250 via the discharge pipe 234, and supplies the refrigerant flowing out of the indoor unit 270 to the compressor 230 via the suction pipe 233. When switched to heating mode, the four-way valve 240 supplies the refrigerant discharged from the compressor 230 to the indoor unit 270 via the discharge pipe 234, and supplies the refrigerant flowing out from the outdoor heat exchanger 250 to the compressor 230 via the suction pipe 233.

[0072] The outdoor heat exchanger 250 is connected to the expansion valve 260 via a refrigerant pipe 430. An outdoor air blower F1 is disposed near the outdoor heat exchanger 250. The outdoor air blower F1 is rotated by the first motor 1A to draw outside air into the outdoor unit 210 and release the outside air that has exchanged heat with the refrigerant in the outdoor heat exchanger 250 to the outside of the outdoor unit 210. In the cooling mode, the outdoor heat exchanger 250 exchanges heat between the refrigerant supplied from the four-way valve 240 and the outside air taken into the outdoor unit 210, and supplies the refrigerant that has undergone heat exchange to the expansion valve 260. In the heating mode, the outdoor heat exchanger 250 exchanges heat between the refrigerant supplied from the expansion valve 260 and the outside air taken into the outdoor unit 210, and supplies the refrigerant that has undergone heat exchange to the four-way valve 240.

[0073] The expansion valve 260 is connected to the indoor unit 270 via a refrigerant pipe 430. In the cooling mode, the expansion valve 260 reduces the pressure of the refrigerant supplied from the outdoor heat exchanger 250 by adiabatic expansion, and supplies the low-temperature, low-pressure two-phase refrigerant to the indoor unit 270. In the heating mode, the expansion valve 260 reduces the pressure of the refrigerant supplied from the indoor unit 270 by adiabatic expansion, and supplies the low-temperature, low-pressure two-phase refrigerant to the outdoor heat exchanger 250. Furthermore, the expansion valve 260 is controlled by the outdoor unit control unit 100A to adjust its opening degree, and in the heating mode, it adjusts the flow rate of refrigerant supplied from the indoor unit 270 to the outdoor heat exchanger 250. In the cooling mode, it adjusts the flow rate of refrigerant supplied from the outdoor heat exchanger 250 to the indoor unit 270.

[0074] The indoor unit 270 has an indoor heat exchanger 280, an indoor fan 150A (blower), and an indoor unit control unit 100B. The indoor fan 150A (blower) is disposed near the indoor heat exchanger 280, and is rotated by a second motor 1B to take in indoor air into the indoor unit 270 and release the indoor air that has exchanged heat with the refrigerant in the indoor heat exchanger 280 into the room.

[0075] The indoor heat exchanger 280 is connected to the four-way valve 240 via a refrigerant pipe 420 and to the expansion valve 260 of the outdoor unit 210 via a refrigerant pipe 430. The indoor heat exchanger 270 functions as an evaporator when the air conditioning apparatus 200 is switched to a cooling mode, and functions as a condenser when the air conditioning apparatus 200 is switched to a heating mode. That is, in the cooling mode, the indoor heat exchanger 280 exchanges heat between the low-temperature, low-pressure two-phase refrigerant supplied from the expansion valve 260 and the indoor air taken into the indoor unit 270, releases the heat-exchanged indoor air into the room, and supplies the heat-exchanged refrigerant to the four-way valve 240. In the heating mode, the indoor heat exchanger 270 exchanges heat between the refrigerant supplied from the four-way valve 240 and the indoor air taken into the indoor unit 270, releases the heat-exchanged indoor air into the room, and supplies the heat-exchanged refrigerant to the expansion valve 260.

[0076] FIG. 9 is a cross-sectional side view of a main portion of a heat source unit (outdoor unit 210) in a refrigeration cycle apparatus (air conditioner 200) equipped with a blower F (outdoor blower F1) of the present invention. The first motor 1A corresponds to the motor 1 in the blower F of the present invention. The first motor 1A has support legs 11 protruding from the outer peripheral surface of the resin outer casing 10 fixed to a support base 220 of the outdoor unit 210. An impeller 300 is attached to an output end 61 (impeller fixing portion) of the shaft 6 of the first motor 1A. The impeller 300 provided in the blower F1 in this embodiment is a propeller fan (axial fan).

[0077] In this embodiment, the propeller fan, which is the impeller 300 included in the blower F (outdoor blower F1), has a mass of approximately 1.5 kg, and the radial load applied to the bearings (first bearing 7, second bearing 8) via the output end 61 (impeller fixing portion) supporting the propeller fan is approximately 36 N. Thus, when the radial load applied to the bearings supporting the impeller 300 is large (e.g., 10 N or more, particularly 20 N or more), the lubricant film thickness in the bearings (first bearing 7, second bearing 8) of the motor 1 is likely to be insufficient, resulting in noise generation, particularly when the motor 1 is driven at low speed. Therefore, in this embodiment, even when the motor 1 is driven at low speed with a large radial load applied to the output end 61, urea grease G is used as the lubricant in the bearings (7, 8) of the motor 1, thereby preventing metal-to-metal contact within the bearings and suppressing noise generation in the bearings.

[0078] In this embodiment, the motor 1 has been described as being used in the blower F1 (outdoor fan) mounted in the heat source unit (outdoor unit 210) of the refrigeration cycle apparatus (air conditioner 200), but the present invention is not limited to this and the motor 1 may also be used in the indoor blower F2 (indoor fan 150B) mounted in the user unit (indoor unit 270) of the refrigeration cycle apparatus (air conditioner 200). Similarly, the motor 1 may be used in both the outdoor blower F1 (outdoor fan 150A) mounted in the heat source unit (outdoor unit 210) of the refrigeration cycle apparatus (air conditioner 200) and the indoor blower F2 (indoor fan 150B) mounted in the user unit (indoor unit 270). In addition, in the present embodiment, the impeller 300 of the blower F (outdoor fan 150A) on which the motor 1 is mounted is an axial flow fan (e.g., a propeller fan), but of course, this is not limited thereto. The impeller 300 of the blower F on which the motor 1 is mounted may be a centrifugal fan (e.g., a sirocco fan, a turbo fan, etc.) or a cross-flow fan (e.g., a cross-flow fan). In addition, while an outdoor unit of an air conditioner has been illustrated as the heat source unit of a refrigeration cycle apparatus on which the outdoor blower F1 is mounted, this is not limited thereto. The outdoor blower F1 may be mounted in a chiller unit (not shown). In addition, while an indoor unit of an air conditioner has been illustrated as the user side unit of a refrigeration cycle apparatus on which the indoor blower F2 is mounted, this is not limited thereto. The blower F1 may be mounted in a fan coil unit (not shown).

[0079] [Air Purifier] In the present embodiment, the blower F equipped with the motor 1 has been described as the outdoor blower F1 equipped in the outdoor unit 210 of the air conditioner 200, but the present invention is not limited to this and may also be used in an air purifier. Fig. 10 is a cross-sectional view taken vertically from the center of an air purifier 500 equipped with the blower F.

[0080] As shown in FIG. 10 , an air purifier 500 has a housing formed with an air passage 510 that guides air introduced through an air inlet 511 to an air outlet 512. A blower F3 is provided along the air passage 510 to circulate the air in the air passage 510 from the air inlet 511 toward the air outlet 512. The blower 150C of the blower F3 is configured as a sirocco fan 1C' equipped with a motor 1C. The impeller 300 of the blower 150C is preferably a sirocco fan 1C', which is a centrifugal fan, but is not limited thereto and may be any other fan capable of circulating air. For example, the impeller 300 may be an axial fan, a cross-flow fan, or any other fan.

[0081] In addition, a pre-filter 520, a dust collection filter 521, a deodorizing unit 530, a unit guide 531, and a humidifying unit 540 are arranged in air passage 510 between air intake port 511 and blower 150C. Furthermore, an ozonizer 550 that generates ozone to sterilize and deodorize the air is arranged in air passage 510 between blower 150C and air outlet 512.

[0082] That is, by rotating the impeller 300, air is drawn into the air purifier 500 from the surroundings, and dust and other particles are removed from the air by the filters (pre-filter 520, dust collection filter 521), before being discharged into the surroundings. In this case, by configuring the motor 1C that drives the blower (fan) 150C of the blower device F3 as described above, the air purifier 500 can be operated continuously for long periods of time with the blower (fan) 150C rotating at a low speed.

[0083] In this embodiment, the blower F on which the motor 1 is mounted has been described as the blower F1 mounted in the heat source unit (outdoor unit 210 of the air conditioner) of the refrigeration cycle apparatus (air conditioner 200), but the present invention is not limited to this and may also be used in a ventilation unit 600. Fig. 11 is a conceptual diagram showing a ventilation unit 600 on which the blower F is mounted.

[0084] As shown in Figure 11, the ventilation unit 600 includes a casing 610 that houses a total heat exchanger 620. The casing 610 is provided with an outdoor air supply port 611, an indoor air supply port 612, an indoor air exhaust port 613, and an outdoor air exhaust port 614. An air supply-side passage 621 and an exhaust-side passage 622 are formed in the internal space of the casing 610. One end of the air supply-side passage 621 is connected to the outdoor air supply port 611, and the other end is connected to the indoor air supply port 612. One end of the exhaust-side passage 622 is connected to the indoor air exhaust port 613, and the other end is connected to the outdoor air exhaust port 614.

[0085] The total heat exchanger 620 may be a rotary type or a stationary type. An intake-side passage 621 and an exhaust-side passage 622 both pass through the total heat exchanger 620. That is, the intake-side passage 621 passes through one flow path of the total heat exchanger 620, and the exhaust-side passage 620 passes through the other flow path of the total heat exchanger 622. In other words, the total heat exchanger 620 is provided midway through the intake-side passage 621 and midway through the exhaust-side passage 622.

[0086] In the ventilation unit 600, outdoor air flows toward the room through the air supply-side passage 621, and indoor air flows toward the outside through the air exhaust-side passage 622. The indoor air flowing through the air supply-side passage 621 and the indoor air flowing through the air exhaust-side passage 622 exchange sensible heat and latent heat in the total heat exchanger 620. As a result, total heat exchange occurs between the air flowing through the air supply-side passage 621 and the air flowing through the air exhaust-side passage 622.

[0087] The ventilation unit 600 further includes an intake fan 150d (air blower) and an exhaust fan 150e (air blower). The intake fan 150d is disposed downstream of the total heat exchanger 620 in the intake-side passage 621 (i.e., on the indoor-side intake port 612 side). The exhaust fan 150e is disposed downstream of the total heat exchanger 620 in the exhaust-side passage 622 (i.e., on the outdoor-side exhaust port 614 side).

[0088] The ventilation unit 600 includes a control unit 630. The control unit 630 is electrically connected to the motor 1d of the air supply fan 150d and the motor 1e of the exhaust fan 150e, and controls the rotation speed of each motor (1d, 1e). Note that the control unit 630 may be disposed inside or outside the ventilation unit 630, as long as it is configured to control the rotation speed of the motors (1d, 1e). The control unit 630 may also be provided as two separate control units that individually control the motors 1d and 1e.

[0089] The ventilation unit 600 shown in FIG. 11 exhausts indoor air to the outside by rotating the impeller 300 provided on the exhaust fan 150e (blower) of the air blower F4. By configuring the motor 1e that drives the exhaust fan 150e (blower) as described above, the ventilation unit 600 equipped with the air blower F4 can be operated continuously for a long period of time with the exhaust fan 150e rotating at a low speed. While the example shown here uses urea grease for the motor 1e of the exhaust fan 150e and causes the control unit 630 to continuously rotate the motor 1e at a low speed for a long period of time, it is also possible to use urea grease for the motor 1d of the air supply fan 150d and cause the control unit 630 to continuously rotate the motor 1d at a low speed for a long period of time.

[0090] Although the ventilation unit 600 provided with a heat exchanger (total heat exchanger 620) has been described as an example here, it may be a ventilation unit without a heat exchanger. Furthermore, although the ventilation unit provided with both an intake-side passage 621 and an exhaust-side passage 622 has been described as an example here, it may be a ventilation unit provided with only one of the intake-side passage 621 or the exhaust-side passage 622.

[0091] Furthermore, in this embodiment, the motor 1 is not limited to the above-described example, and may be used in a variety of applications. For example, it may be used in a bathroom heater.

[0092] In other words, in a bathroom heater, warm air can be supplied to the bathroom by rotating the impeller 300 of the air blower F toward the bathroom through the pipe that circulates heated water. In this case, by using the motor 1 that drives the fan as described above, the air blower (fan) 150 of the air blower F can operate continuously for long periods of time even at low speeds.

[0093] DESCRIPTION OF SYMBOLS 1...motor 2...stator 3...rotor 4...bracket 5...circuit board 6...shaft 61...output end (impeller fixing portion) 7...first bearing 8...second bearing 10...resin outer shell 71...outer ring 72...inner ring 73...retainer 74...rolling element 100...control unit 150...blower (fan) 200...air conditioner (refrigeration cycle device) 210...outdoor unit (heat source side unit) 270...indoor unit (use side unit) 300...impeller F...blower device G...grease W...bearing space

Claims

1. A blower comprising: a motor with a variable rotational speed, the motor having a stator, a rotor disposed inside the stator, a shaft to which the rotor is fixed, and a bearing rotatably supporting the shaft; and a control unit that controls the rotational speed of the motor, wherein the control unit has at least a rotation mode in which the rotational speed n [rpm] of the motor satisfies 50≦n<100, the bearing has an inner ring, an outer ring, and a plurality of rolling elements provided in an annular bearing space formed between the inner ring and the outer ring, and urea-based grease filled in the bearing space, and the blower is capable of maintaining the motor in the rotational mode for a period of time longer than 5 hours.

2. A blower according to claim 1, wherein the blower is capable of maintaining the rotation mode for a period of time longer than 24 hours.

3. A blower according to claim 1, wherein the rotation speed n [rpm] of the motor in the rotation mode satisfies 50≦n<80.

4. A blower according to claim 3, wherein the urea-based grease contains a base oil, an additive, and a thickener, the thickener containing a urea group, and the base oil has a kinematic viscosity ν of 40 [mm ２ / s] or more.

5. A blower according to claim 4, wherein the base oil has a kinematic viscosity ν of 80 [mm ２ / s] or more.

6. A blower according to claim 1, wherein the motor further has an impeller fixing portion on one end side of the shaft to which an impeller is attached.

7. A blower according to claim 6, wherein the radial load applied to the bearing is 10 N or more.

8. A heat source side unit of a refrigeration cycle device, comprising the air blower according to claim 1.

9. A user side unit of a refrigeration cycle device, comprising the air blower according to claim 1.

10. A refrigeration cycle device comprising at least one of the heat source unit of claim 8 and the user unit of claim 9.

11. A ventilation unit comprising the blower device according to claim 1.

12. An air purifier comprising the blower device according to claim 1.

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