Centrifugal blower

Abstract

To provide a centrifugal blower that is easy to handle, highly reliable, compact, flat, and capable of ensuring sufficient airflow and static pressure while minimizing noise. [Solution] In the annular air passage 4f formed by combining the first case 4a and the second case 4b and circulating around the radially outer side of the case body 4, a first diffuser 4k is provided on the inner circumferential surface of the first air passage 4d, which is inclined diagonally downward from the radially inner side to the radially outer side. At the bottom of the second air passage 4e, a plurality of exhaust holes 4m are drilled at predetermined intervals in the circumferential direction to exhaust compressed air to the outside of the case body 4, and a second diffuser 4n is provided facing each exhaust hole 4m, which is inclined diagonally downward with respect to the rotation direction of the centrifugal fan 2.

Description

TECHNICAL FIELD

[0001] The present disclosure relates to a centrifugal blower used for, for example, seat air conditioning or HVAC (Heating, Ventilation, and Air Conditioning) equipment.

BACKGROUND ART

[0002] When a driver is in prolonged contact with the seat back and the seating portion, such as during long-distance driving, the clinging hot and humid air increases discomfort. For this reason, seat air conditioning devices are used to regulate the hot and humid air that tends to accumulate mainly in the backrest portion and the seating portion.

[0003] As seat air conditioning devices, there are a type that blows air out from the seat and a type that draws in and discharges air from the seat. Here, a suction-type seat air conditioning device that can be expected to provide a more comfortable air conditioning effect will be described. The suction-type seat air conditioning device achieves an air conditioning effect by sucking and removing the hot and humid air accumulated in the backrest portion and the seating portion from the relevant areas.

[0004] For example, a seat air conditioning system that suppresses noise generated when air flows from the seat into the air inlet of the blower has been proposed. A suction port is formed in the upper case part of the case assembled by screwing the four corners of the upper case part and the lower case part, and a motor including a stator and a rotor and a centrifugal multi-blade fan are rotatably supported on the lower case part. The rotor is integrally assembled with the centrifugal multi-blade fan. When the motor rotates and the centrifugal multi-blade fan rotates, air is drawn from the seat side through the air inlet of the upper case part and discharged through the air outlets opened on the four sides of the case (Patent Document 1: Japanese Patent Laid-Open No. 2015-174580).

PRIOR ART DOCUMENTS

PATENT DOCUMENTS

[0005]

PATENT DOCUMENT 1

[0006] In the configuration described in Patent Document 1, the case is open on all four sides, resulting in extremely low rigidity. Therefore, there is a risk that durability against stress loads applied to the sheet, as well as ease of assembly, handling, and reliability, will be reduced. Specifically, if tension is applied to cables such as signal lines and power supply lines connected to the motor board, there is a risk of disconnection, reducing reliability. Furthermore, even if ribs or other features are added to increase the rigidity of the case, it will lead to increased costs, and ingenuity will be required in securing the lead wires, making handling difficult. Furthermore, centrifugal blowers, especially those for automotive applications, are required to be small and flat, while ensuring sufficient airflow and static pressure, and also to be quiet. [Means for solving the problem]

[0007] This disclosure was made to solve these problems, and its purpose is to provide a centrifugal blower that is easy to handle, highly reliable, compact and flat, can secure airflow and static pressure, and can be made quiet.

[0008] To achieve the above objectives, this disclosure comprises the following configuration. A centrifugal blower is provided in which a centrifugal fan and a motor that rotates it are housed within a case, and air is drawn in from the axial center of the case and exhausted from the radially outer bottom of the case, wherein the case comprises a first case that covers and is assembled to enclose the centrifugal fan, has an intake opening in the center and a first air passage formed radially outward, and a second case that rotatably supports the motor and has a second air passage formed radially outward from the outer peripheral end of the centrifugal fan that is combined with the first air passage, and the hub of the centrifugal fan and the main plate connected thereto are shaped on the side opposite to the intake opening The motor is housed in the dome-shaped space formed, overlapping in the axial direction. The first case and the second case are combined to form an annular air passage that circulates radially outward of the case body. The inner surface of the first air passage is provided with a first diffuser that slopes diagonally downward from the radially inward to the radially outward direction. The bottom of the second air passage is provided with a plurality of exhaust holes for exhausting compressed air to the outside of the case body, spaced at predetermined intervals in the circumferential direction. A second diffuser is provided facing each exhaust hole, and it slopes diagonally downward with respect to the rotation direction of the centrifugal fan.

[0009] According to the above configuration, in the annular air passage, a first diffuser is provided on the inner circumferential surface of the first air passage, which is inclined diagonally downward from the radially inward to the radially outward direction, and a second diffuser is provided facing each exhaust port drilled at the bottom of the second air passage, which is inclined diagonally downward with respect to the rotation direction of the centrifugal fan. As a result, even if the exhaust passage from the centrifugal fan to the exhaust port is short, the static pressure can be increased, and even if a load is generated, the airflow can be maintained. In particular, by using the first and second diffusers together, the static pressure can be increased even at low exhaust flow rates. Furthermore, the case housing the centrifugal fan and the motor that rotates it is formed by combining a first case, which has an intake opening in the center and a first air passage formed radially outward, and a second case, which rotatably supports the motor and has a second air passage formed radially outward that is combined with the first air passage. As a result, the case has high rigidity and is easy to handle. In particular, since multiple exhaust holes for exhausting compressed air to the outside of the case are drilled at predetermined intervals in the circumferential direction at the bottom of the second air passage, the sides of the case can be closed, improving the strength of the case. Furthermore, since the motor is housed in a dome-shaped space formed on the side opposite the intake opening by the centrifugal fan hub and the main plate connected thereto, overlapping in the axial direction, the axial dimensions of the centrifugal blower can be reduced, making it possible to make it smaller and flatter even for centrifugal blowers of the same size. In addition, by increasing the outer diameter of the centrifugal fan and expanding the area of ​​the intake and exhaust openings, it is possible to make it smaller and flatter in the axial direction, increasing the airflow even at low rotational speeds, and since there are no partition walls called tongues in the annular air passage that is formed around the radially outer side of the case body, peak noise is not generated, making it quieter.

[0010] Preferably, the inner wall surface of the first air passage forming the first air passage has an inclined surface that slopes diagonally downward from the radially inward to the radially outward direction, and the first diffuser has projections formed at predetermined intervals that connect in an arc shape from a first virtual circle that forms the radially inward end forming the inclined surface to a second virtual circle that forms the radially outward end, with the height gradually increasing when the first case is viewed from above. As a result, the air drawn in from the intake opening by the rotation of the centrifugal fan is guided to the first air passage while being diffused by the first diffuser. The height of the protrusions, which are arranged in an arc from the radially inner end to the radially outer end, gradually increases, thus dispersing the points where peak noise of the frequency component obtained by multiplying the number of impeller blades by the rotation frequency is generated, thereby reducing noise.

[0011] It is preferable that each protrusion is formed such that the angle θ between the first tangent line passing through the intersection point where the radius of the first case and the first virtual circle intersect, and the second tangent line to the arc-shaped protrusion connecting the intersection point on the first virtual circle and the second virtual circle, is between 0° and 90°. This allows the air drawn into the case body from the intake opening of the first case by the rotation of the centrifugal fan to be guided to the first air passage while being diffused by multiple arc-shaped protrusions, thereby increasing the static pressure in the low flow rate range.

[0012] Each diffuser plate constituting the second diffuser may be arranged such that adjacent diffusers in the circumferential direction do not overlap each other in an axial plan view, and the downstream end in the exhaust direction may be a curved shape that is shifted by a predetermined amount in the direction of rotation of the centrifugal fan so as to exhaust in accordance with the rotation of the centrifugal fan. As a result, multiple diffusers are arranged so that adjacent diffusers in the circumferential direction do not overlap with each other in an axial plan view, thus ensuring the required airflow even with a small, flat design. Furthermore, compared to not having a second diffuser, the static pressure can be increased even with a shorter exhaust flow path from the centrifugal fan to the exhaust port. [Effects of the Invention]

[0013] Using the centrifugal blower described above, it is possible to achieve high operability and reliability, a compact and flat design, sufficient airflow and static pressure, and quiet operation. [Brief explanation of the drawing]

[0014] [Figure 1] Figure 1 is a perspective view of a centrifugal blower. [Figure 2] Figure 2 is a perspective view of the centrifugal blower shown in Figure 1 with the first case removed. [Figure 3] Figure 3 is a radial cross-sectional view of the centrifugal blower shown in Figure 1. [Figure 4] Figure 4 is an internal side plan view of the second case. [Figure 5] Figure 5 is an internal perspective view of the second case. [Figure 6]FIG. 6 is an inner surface side perspective view of the first case. [Figure 7] FIG. 7 is a partially enlarged perspective view of the first case in FIG. 6. [Figure 8] FIG. 8 is a plan view of the inner surface side of the first case. [Figure 9] FIG. 9 is a graph showing air flow rate - static pressure characteristics according to the presence or absence of a diffuser on the inner surface of the first case of the centrifugal blower. [Figure 10] FIG. 10A is an inner surface side perspective view when there is no diffuser on the inner surface of the first case, and FIG. 10B to FIG. 10F are inner surface side perspective views when there is a diffuser on the inner surface of the first case, showing cases where the angle θ (inlet angle) formed by the first tangent line L1 and the second tangent line L2 of the protruding ridge constituting the diffuser is changed from 0° to 120° in increments of 30°. [Figure 11] FIG. 11A is a graph showing noise levels according to changes in the inlet angle of the protruding ridge of the first case of the centrifugal blower, and FIG. 11B is a graph showing static pressure characteristics according to changes in the inlet angle of the protruding ridge of the first case of the centrifugal blower. [Mode for Carrying Out the Invention]

[0015] [First Embodiment] Hereinafter, an embodiment of the centrifugal blower according to the present disclosure will be described with reference to the accompanying drawings. First, the schematic configuration of the centrifugal blower will be described with reference to FIG. 1 to FIG. 8. A DC brushless motor is used as the motor M, and an outer rotor type motor is used in the present embodiment. Note that an inner rotor type motor may also be used.

[0016] As shown in FIG. 3, in the centrifugal blower 1, the centrifugal fan 2 and the rotor 3 are integrally assembled, and the motor M that rotationally drives these components is accommodated in the case body 4. As shown in FIG. 1, the centrifugal blower 1 draws in air from the axially central portion of the case body 4, and discharges pressurized air from the radially outer side along the axial direction. The case body 4 is formed by combining a first case 4a that is assembled to cover the centrifugal fan 2, and a second case 4b that rotatably supports the motor M (the rotor 3 and the stator 5: see FIG. 3).

[0017] As shown in Figure 1, an intake opening 4c is provided in the center of the first case 4a, and as shown in Figure 3, a first air passage 4d is formed radially outward. As shown in Figure 2, a second air passage 4e is formed radially outward of the second case 4b, which is combined with the first air passage 4d. By combining the first case 4a and the second case 4b, an annular air passage 4f is formed radially outward of the case body 4.

[0018] As shown in Figure 3, the second case 4b has a bearing holder 6 and a motor board 7 assembled in the center. The stator core 5a is integrally fixed to the outer circumference of the bearing holder 6, and the rotor shaft 3a is rotatably supported in the shaft hole of the bearing holder 6 via a bearing 6a. The stator coil 5b is wound around the pole teeth formed on the stator core 5a, and the tips of the pole teeth are positioned opposite the rotor magnet 3c. The lead wires of the stator coil 5b are connected to the motor board 7, and a Hall sensor for detecting the position of the rotor magnet 3c is mounted on it. If the motor M is a sensorless type, the position detection sensor can be omitted. One end of the rotor shaft 3a is integrally assembled to the hub of the cup-shaped rotor yoke 3b by press-fitting, shrink-fitting, bonding, or a combination of these. The other end of the rotor shaft 3a is supported by a shaft support 6b provided in the bearing holder 6. The shaft support 6b is supported by a board support 7a that supports the motor board 7. A rotor magnet 3c is integrally mounted on the inner circumferential surface of the rotor yoke 3b. Note that the intake opening 4c does not need to have its center precisely aligned with the axis of the rotor shaft 3a of the motor M; it is sufficient that the intake opening 4c is located near the axial center of the case body 4, within a range that allows the centrifugal fan 2 to operate without reducing efficiency.

[0019] As shown in Figure 2, the centrifugal fan 2 has a main plate 2b that extends radially outward from the hub 2a and is formed in a dome shape. The main plate 2b, which is continuous with the hub 2a, extends radially outward and is inclined downstream in the airflow direction, and multiple impellers 2c are formed upright on the main plate 2b, curving from the radially inward to the radially outward direction. Near the radially outward edge (outer peripheral edge) of the impellers 2c formed upright on the main plate 2b, auxiliary impellers 2d are formed upright at equal intervals from adjacent impellers 2c (in the center between the impellers 2c). This reduces pressure pulsation for each blade, thereby suppressing the generation of peak noise due to interference with the diffuser. Air drawn in from the intake opening 4c facing the hub 2a of the centrifugal fan 2 is pressurized by the impellers 2c and auxiliary impellers 2d formed on the main plate 2b and sent out towards the annular airflow passage 4f provided radially outward. An annular shroud 2e is connected to the outer peripheral edge of the impeller 2c and auxiliary impeller 2d, which rectifies the pressurized air from the impeller 2c and auxiliary impeller 2d and sends it out towards the outer annular airflow passage 4f (see Figure 3).

[0020] Furthermore, as shown in Figure 3, the hub 2a of the centrifugal fan 2 and the main plate 2b connected thereto form a dome-shaped space 4g on the side opposite to the intake opening 4c. This dome-shaped space 4g can be used to house tall components (such as electrolytic capacitors 7b) mounted on the motor M and motor board 7, allowing the centrifugal fan 2 and motor M to be assembled compactly. In addition, the rotor 3 and stator 5 of the motor M are housed in the dome-shaped space 4g, overlapping in the axial direction. This reduces the axial dimensions of the centrifugal blower 1, making it possible to make it smaller and flatter even if the centrifugal blower 1 is the same size.

[0021] As shown in Figure 1, the first case 4a and the second case 4b are assembled together by overlapping them with their openings facing each other and locking the locking piece 4h provided on the outer circumference of the side of the first case 4a with the locking portion 4i provided on the outer circumference of the side of the second case 4b. In addition, the first case 4a and the second case 4b have wiring connection ports 4j formed therein for routing wiring connected to the motor board 7 outside the case.

[0022] As shown in Figure 3, the side portion of the first case 4a, which is adjacent to the upper portion where the intake opening 4c is provided, forms the first air passage 4d. The inner wall surface of this side portion has an inclined surface 4d1 that slopes diagonally downward from the radially inward to the radially outward direction. The first diffuser 4k is formed on the inclined surface 4d1, extending from the radially inward to the radially outward direction.

[0023] As shown in Figures 6 and 7, a first diffuser 4k is formed on an inclined surface 4d1 provided on the side of the first case 4a. Specifically, a plurality of protrusions 4k1 are formed on the inclined surface 4d1 at predetermined intervals, arranged in an arc shape such that the height gradually increases from the radially inward to the radially outward side.

[0024] Figure 8 is an internal plan view of the first case 4a. As shown in Figure 8, let O be the center of the intake opening 4c of the first case 4a, and let r be the radius of the first case 4a extending radially outward from the center O. When the inner surface of the first case 4a is viewed from above, a first virtual circle C1 corresponding to the radially inner end and a second virtual circle C2 corresponding to the radially outer end are formed concentrically on the inclined surface 4d1. Multiple protrusions 4k1 are formed in an arc shape to connect the first virtual circle C1 and the second virtual circle C2.

[0025] As shown in Figure 8, let M be the intersection point between the radius r of the first case 4a and the first virtual circle C1 that intersects it, and let L1 be the first tangent line passing through intersection M of the first virtual circle C1. Also, let L2 be the second tangent line to the arc-shaped projection 4k1 passing through intersection M on the first virtual circle C1. At this time, each projection 4k1 is provided such that the angle θ (entrance angle) between the first tangent line L1 and the second tangent line L2 is between 0° and 90°. In Figure 8, the case where the entrance angle θ of the projection 4k1 is 60° is shown as an example (the same applies to Figures 6 and 7). Multiple such projections 4k1 are formed on the inclined surface 4d1 at predetermined intervals in the circumferential direction. Note that the multiple projections 4k1 are formed integrally during the resin molding of the first case body 4a. The form of the first diffuser 4k is not necessarily limited to projections, but may also be plate-shaped such as a diffusion plate.

[0026] This allows the air drawn into the case from the intake opening 4c of the first case 4a by the rotation of the centrifugal fan 2 to be diffused by the protrusions 4k1 that make up the first diffuser 4k, increasing its static pressure and guiding it to the first air passage 4d. Furthermore, since the height of the protrusions 4k1 that connect in an arc shape from the inner diameter side to the outer diameter side of the inclined surface 4d1 of the first case 4a is progressively higher, it is possible to disperse the points where peak noise of the frequency component obtained by multiplying the number of blades of the impeller 2 by the rotation frequency is generated, thereby reducing noise.

[0027] As shown in Figure 4, multiple exhaust holes 4m are drilled circumferentially on the outer circumference of the bottom of the second case 4b, which serves as the second airflow passage 4e, to exhaust pressurized compressed air along the axial direction. Each exhaust hole 4m is separated and formed by multiple diffusers 4n1 that constitute the second diffuser 4n, which is located at the bottom of the second case 4b. Each diffuser 4n1 is installed between the bottom outer circumferential wall 4p1 and the bottom inner circumferential wall 4p2. The multiple diffusers 4n1 are arranged so that adjacent diffusers 4n1 do not overlap each other in an axial plan view in the circumferential direction.

[0028] Specifically, as shown in Figure 5, the multiple diffusers 4n1 constituting the second diffuser 4n have a curved shape with a curved surface on the downstream end in the exhaust direction that is shifted by a predetermined amount in the rotation direction E of the centrifugal fan 2, so as to exhaust air in accordance with the rotation of the centrifugal fan 2 in the direction of the arrow. The exhaust holes 4m are formed between adjacent diffusers 4n1. It is preferable that the end face corners 4n2 of the diffusers 4n1 facing the exhaust holes 4m are chamfered. In addition, each diffuser 4n1 is connected in an arc shape from the bottom inner peripheral wall 4p2 to the bottom outer peripheral wall 4p1 when viewed from above on the inner surface of the second case 4b, and is installed in an inclined position toward diagonally downward. The second diffuser 4n exhausts the air exhausted axially from the exhaust holes 4m provided in the second air passage 4e toward diagonally downward relative to the rotation direction of the centrifugal fan 2, along the inclination of each diffuser 4n1 as shown by arrow F in Figure 5.

[0029] As a result, multiple diffusers 4n1 are arranged so that adjacent diffusers 4n do not overlap each other in an axial plan view, and the required airflow can be secured even if the diffuser is small and flat. Compared to not having a second diffuser 4n, the static pressure can be increased even if the exhaust flow path from the centrifugal fan 2 to the exhaust port 4m is shorter.

[0030] Here, the airflow-static pressure characteristics (PQ characteristics) when only the second diffuser 4n is installed in the second case 4b, and when the first diffuser 4k is installed in the first case 4a and the second diffuser 4n is installed in the second case 4b are shown in the graph in Figure 9. The solid line graph shows the airflow-static pressure characteristics (PQ characteristics) when the first diffuser 4k is installed in the first case 4a and the second diffuser 4n is installed in the second case 4b. The dashed line graph shows the airflow-static pressure characteristics (PQ characteristics) when only the second diffuser 4n is installed in the second case 4b. According to the graph above, it was found that the static pressure in the low flow rate range can be increased when the first diffuser 4k is installed in the first case 4a (solid line graph) compared with the case 4a without the first diffuser 4k (dashed line graph).

[0031] Figure 10A shows an internal side perspective view of the first case 4a without the first diffuser 4k (see Figure 8). Figures 10B to 10F show internal side perspective views of the first case 4a with the first diffuser 4k installed. Figures 10B to 10F show the case where the angle θ (inlet angle; see Figure 8) between the first tangent L1 and the second tangent L2 of the protrusion 4k1 constituting the first diffuser 4k is changed in 30° increments between 0° and 120°. Six types of centrifugal blowers 1 with different internal side configurations of the first case 4a were prepared, and fan noise was evaluated under the condition that the airflow rate of each centrifugal blower 1 was the same, with a microphone placed 1m away from the intake hole 4c. In addition, the static pressure characteristics (so-called PQ characteristics) of the fan at different flow rates were evaluated separately.

[0032] The measurement results are shown in Figures 11A and 11B. As can be seen from the graph in Figure 11A, when the first diffuser 4k is installed in the first case 4a, it was found that fan noise at the same flow rate can be suppressed when the inlet angle of the protrusion 4k1 constituting the first diffuser 4k is between 0° and 90°. Also, as can be seen from the graph in Figure 11B, when the first diffuser 4k is installed in the first case 4a, it was found that the static pressure at the same flow rate increases when the inlet angle of the protrusion 4k1 is between 0° and 90°.

[0033] As explained above, in the annular air passage 4f, a first diffuser 4k is provided on the inner surface of the first air passage 4d, which has multiple diffusion plates that are inclined diagonally downward from the radially inward to the radially outward direction. A second diffuser 4n is provided facing each exhaust hole 4m drilled at the bottom of the second air passage 4e, and is inclined diagonally downward with respect to the rotation direction of the centrifugal fan. As a result, even if the exhaust passage from the centrifugal fan 2 to the exhaust hole 4m is short, the static pressure can be increased, and the airflow can be secured even when a load is generated. In particular, by using the first diffuser 4k and the second diffuser 4n together, the static pressure can be increased even at low exhaust flow rates. Furthermore, the case body 4 that houses the centrifugal fan 2 and the motor M that rotates it is formed by combining a first case 4a, which has an intake opening 4c in the center and a first air passage 4d formed radially outward, and a second case 4e, which rotatably supports the motor M and has a second air passage 4e that is combined with the first air passage 4d on the radially outward side. As a result, the case body 4 has high rigidity and is easy to handle. In particular, since multiple exhaust holes 4m for exhausting compressed air to the outside of the case body 4 are drilled at predetermined intervals in the circumferential direction at the bottom of the second air passage 4e, the sides of the case body 4 can be closed, improving the strength of the case body 4. Furthermore, since the motor M is housed in a dome-shaped space 4g formed on the side opposite to the intake opening 4c by the hub 2a of the centrifugal fan 2 and the main plate 2b connected thereto, the axial dimensions of the centrifugal blower 1 can be reduced, making it smaller and flatter even for centrifugal blowers of the same size. In addition, by increasing the outer diameter of the centrifugal fan 2 and expanding the area of ​​the intake opening 4c and exhaust hole 4m, it is possible to make it smaller and flatter in the axial direction and increase the airflow even at low rotational speeds. Moreover, since there are no partition walls called tongues in the annular air passage 4f that is formed by circulating around the radially outer side of the case body 4, peak noise is not generated, making it quieter.

[0034] Here, we will explain in detail the effects of the centrifugal blower 1 of this disclosure on vehicle air conditioning. When the centrifugal blower 1 is installed on a vehicle seat for the purpose of suction-type seat air conditioning, the noise generated during the operation of the centrifugal blower 1, which involves "the centrifugal fan 2 rotating to draw in air axially, generating an airflow in the outer direction within the case body 4, changing direction near the outer edge of the case body 4, and exhausting air in the opposite direction to the intake direction at the outer edge," is proportionally larger than the noise of the entire seat air conditioning system. The flow path from the intake port on the seat surface to the centrifugal blower 1 is short, and the exhaust port of the centrifugal blower 1 has a sufficient flow path cross-sectional area relative to the exhaust flow rate, so noise sources other than the blower are limited. Therefore, it is possible to clearly distinguish between noise from sources other than the blower and noise from the centrifugal blower 1. Because the noise generation factors and output characteristics of the centrifugal blower 1 are contained within the case body 4, the characteristics of the blower (output and noise) remain constant. Furthermore, as mentioned above, the rigidity of the case body 4 is high, which increases the freedom of the mounting position and shape of the sheet to which the centrifugal blower 1 is attached, making it applicable to many types of sheets and enabling cost reduction through economies of scale. Furthermore, by standardizing the characteristics (output and noise), the accuracy of simulating seat air conditioning characteristics for occupant comfort improves from the vehicle design stage, resulting in the secondary effect of reducing the design man-hours for vehicle manufacturers. Furthermore, compared to the suction-type sheet air conditioning system disclosed in the aforementioned prior art document (Patent Document 1: JP 2015-174580 A), the centrifugal blower 1 of this disclosure has the effect of enabling miniaturization of the sheet. Unlike the present disclosure, the blower disclosed in Patent Document 1 exhausts air radially (towards the outer circumference) of the rotating shaft. Therefore, as mentioned above, there are concerns about the blower's durability against mechanical stress, requiring a robust design, which increases its dimensions and weight. In addition, in order to process the exhaust at the rear end of the seat (the rear end in the case of the backrest, or the lower end in the case of the seat surface), it is necessary to provide a connection part to the blower, such as an internal duct in the seat or a rear outlet on the back of the seat, which further increases its dimensions and weight. In contrast, centrifugal blower 1 can exhaust air directly from the rear of the back of the seat through the seat surface, and its high rigidity and omission of attachments allow it to be smaller compared to the centrifugal blower in Patent Document 1. Conventional vehicle seats do not have components such as blowers for the purpose of air conditioning, and a seat with a blower installed would essentially have a foreign object present within the seat cushion. In order for a seated occupant to not perceive the blower as a foreign object, the blower would need to be made smaller or the seat cushion thickness increased. Considering the recent trend towards lighter and smaller vehicles, it is clear that the centrifugal blower 1 of this disclosure has an effect in line with this trend.

[0035] Furthermore, although the above embodiment was described using an in-vehicle seat air conditioning system as an example, it may be used for centrifugal blowers for HVAC (heating, ventilation, and air conditioning) systems, etc. For example, the centrifugal blower 1 disclosed herein can be used for vehicle HVAC systems other than seat air conditioning systems. Conventionally, in automobiles, air conditioning blowers (such as those with a scroll-type casing with a tongue) have been placed in surplus space, but due to the miniaturization of automobiles in recent years and the expansion of living space, surplus space has decreased, and because electric vehicles have a different body structure than conventional automobiles, considering the space for placing air conditioning blowers has become a problem that troubles automobile designers. By adopting a blower with features such as a thin profile, high pressure, and intake and exhaust in the same direction, such as the centrifugal blower 1 disclosed herein, the design freedom of automobiles can be improved. In conventional automobiles, HVAC-related equipment is concentrated around the front seat knees due to the placement of the blowers, but with the centrifugal blower 1, multiple units can be distributed and placed on the ceiling, side walls, doors, etc. By combining it with thermoelectric elements such as Peltier elements, space-saving distributed air conditioning can be realized, which can also contribute to the design of automobiles with high space utilization efficiency. Needless to say, this disclosure is equally effective in locations other than vehicles where there is little surplus space and it is difficult to secure space to install conventional air conditioning fans. [Explanation of symbols]

[0036] 1 Centrifugal blower 2 Centrifugal fan 2a Hub 2b Main plate 2c Impeller 2d Auxiliary impeller 2e Shroud 3 Rotor 3a Rotor shaft 3b Rotor yoke 3c Rotor magnet 4 Case body 4a First case 4b Second case 4c Intake opening 4d First air passage 4d1 Inclined surface 4e Second air passage 4f Annular air passage 4g Dome-shaped space 4h Locking piece 4i Locking part 4j Wiring connection port 4k First diffuser 4k1 Protrusion 4m Exhaust hole 4n Second diffuser 4n1 Diffuser plate 4n2 End face corner 4p1 Bottom outer wall 4p2 Bottom inner wall 5 Stator 5a Stator core 5b Stator coil 6 Bearing holder 6a Bearing 6b Shaft support 7 Motor board 7a Board support 7b Electrolytic capacitor M Motor

Claims

1. A centrifugal fan and a motor that rotates it are housed within a case, and the centrifugal blower draws in air from the axial center of the case and exhausts air from the radially outer bottom of the case, The case body comprises a first case which is assembled to cover the centrifugal fan, has an intake opening in the center, and has a first air passage formed radially outward, The motor is rotatably supported by a second case, and a second air passage is formed radially outward from the outer peripheral end of the centrifugal fan, which is combined with the first air passage. The motor is housed in a dome-shaped space formed on the side opposite to the intake opening by the hub of the centrifugal fan and the main plate connected thereto, with the motors overlapping in the axial direction. A centrifugal blower characterized in that, in an annular air passage formed by combining the first case and the second case and circulating around the radially outer side of the case body, a first diffuser is provided on the inner circumferential surface of the first air passage, which is inclined diagonally downward from the radially inner side to the radially outer side, and a plurality of exhaust holes for exhausting compressed air to the outside of the case body are drilled at predetermined intervals in the circumferential direction at the bottom of the second air passage, and a second diffuser is provided at a position facing each exhaust hole, which is inclined diagonally downward with respect to the rotation direction of the centrifugal fan.

2. The centrifugal blower according to claim 1, wherein the inner wall surface of the first air passage forming the first air passage is formed with an inclined surface that slopes diagonally downward from the radially inward to the radially outward direction, and the first diffuser has projections formed at predetermined intervals that are connected in an arc shape so that the height gradually increases from a first virtual circle that forms the radially inward end forming the inclined surface when the first case is viewed in plan, toward a second virtual circle that forms the radially outward end.

3. The centrifugal blower according to claim 2, wherein each protrusion is formed such that the angle θ between the first tangent line passing through the intersection point where the radius of the first case and the first virtual circle intersect, and the second tangent line to the arc-shaped protrusion connecting the intersection point on the first virtual circle and the second virtual circle, is between 0° and 90°.

4. The centrifugal blower according to claim 1 or claim 2, wherein each diffuser plate constituting the second diffuser is arranged such that adjacent diffusers in the circumferential direction do not overlap each other in an axial plan view of the second case, and the downstream end in the exhaust direction has a curved shape that is shifted by a predetermined amount in the direction of rotation of the centrifugal fan so as to exhaust in accordance with the rotation of the centrifugal fan.

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