Patent Description:
Leaf blowers are mainly used for blowing away fallen leaves, road surface dust, accumulated water and accumulated snow, etc. Common types of blower include petrol blowers and electric blowers. During operation, a petrol blower is powered by a petrol engine; fan blades rotate inside a fan volute, producing a wind which blows out through an air outlet to perform a job. In contrast to a petrol blower, an electric blower in which the fan is driven to rotate by a motor is small in volume, light in weight and convenient to operate, and is therefore popular among consumers.

When an electric blower is operating, electronic components on a circuit board for controlling the motor generate heat, causing a rapid increase in the temperature of the circuit board and its surroundings. The electronic components will fail due to overheating if this heat is not promptly dissipated. To prevent the electronic components from being damaged by heat, a cooling mechanism needs to be provided for the circuit board. A conventional cooling mechanism comprises a heat sink mounted on the circuit board and an independent air channel for cooling, enabling external air to carry away heat from the circuit board and the heat sink. However, the heat sink increases the weight of the blower, and it is difficult to ensure that a sufficient quantity of cooling air enters the independent air channel. The <CIT> discloses a portable blower having a sound-insulated blower tube enclosing the electric motor and fan assembly, wherein the fan unit is positioned within a hollow support tube with openings on one or both ends for directing a forced convection cooling airflow to the brushless DC electric motor.

<CIT>, <CIT>, <CIT> and <CIT> disclose other relevant background art.

To overcome the above deficiencies, the present invention provides a blower as defined by claim <NUM>, which utilizes a working airflow generated by the fan when rotating to cool the circuit board. The blower comprises: a blower body, having accommodated therein a fan and a drive unit, a rotation shaft of the fan defining a longitudinal axis, and the blower body defining an air inlet; a blow pipe, attached to the blower body and extending along the longitudinal axis, the blow pipe defining an air outlet; a control unit, for controlling operation of the drive unit, wherein the blower defines an airflow path extending from the air inlet to the air outlet, the control unit being at least partially located in the airflow path, such that when the blower is operating, at least a portion of an airflow entering the air inlet cools the control unit and is then discharged through the air outlet.

In one embodiment, the control unit is arranged close to the drive unit. Preferably, the control unit is substantially transverse to the longitudinal axis.

The drive unit comprises a motor, and the control unit comprises a control circuit board located at an end of the motor. Preferably, in an airflow direction, one of the control circuit board and the fan is located downstream of the motor while the other is located upstream of the motor.

The blower body comprises a casing in which the fan, motor and control circuit board are located. Preferably, the casing comprises a hollow tapered flow-guiding body, with an opening formed in a surface and/or an extremity of the tapered flow-guiding body. More preferably, multiple openings spaced apart circumferentially are formed in the surface of the tapered flow-guiding body, each of the openings being enclosed by two arcs and two sides, the two arcs being arc sections on two circles of different radii centered at the center of the extremity of the tapered flow-guiding body.

In one embodiment, the blower body comprises a guard defining the air inlet, and in the direction of the longitudinal axis, the ratio of a distance between the control circuit board and the air inlet and a distance between the control circuit board and the air outlet is <NUM> - <NUM>.

In one embodiment, the motor is a brushless DC motor controlled in a sensorless fashion, and no heat sink is present on the control circuit board.

The casing comprises an outer ring and an inner ring, the tapered flow-guiding body being connected to the inner ring, and the control circuit board being located in a space defined by the tapered flow-guiding body and the inner ring. Preferably, at least a part of the tapered flow-guiding body protrudes beyond the outer ring, with the opening being formed in said at least one part.

The tapered flow-guiding body further comprises a wing part, the wing part having an inner wall, an outer wall located at a radially outer side of the inner wall, and a connecting part which connects the inner wall to the outer wall; and an inner ring slot and an outer ring slot which mate with the inner wall and the outer wall are formed in the inner ring and the outer ring of the casing respectively. Preferably, a part of the inner ring slot that is not occupied by the inner wall forms an inner ring hole, the control circuit board being located downstream of the inner ring hole.

In one embodiment, a cross section of the control circuit board corresponds to a cross section of the motor. Preferably, the ratio of a cross-sectional area of the control circuit board to a cross-sectional area of a motor housing is <NUM> - <NUM>, more preferably <NUM> - <NUM>.

In one embodiment, the ratio of a cross-sectional area of the control circuit board to an area enclosed by the inner ring is <NUM> - <NUM>, preferably <NUM> - <NUM>. The ratio of the cross-sectional area of the control circuit board to an area enclosed by the outer ring is <NUM> - <NUM>, preferably <NUM> - <NUM>.

In one embodiment, the control circuit board is connected to a motor housing by means of a fastener, and at least a part of the motor is not covered by the motor housing.

In one embodiment, the motor housing comprises a first housing part located at one end of the motor and a second housing part located at the other end of the motor, the control circuit board being fixed to the second housing part, and the second housing part comprising a bottom wall and a sidewall; a first set of fastener holes is formed in the sidewall, a second set of fastener holes is formed in the bottom wall, and at least one opening leading to the interior of the motor is formed in the sidewall.

In one embodiment, the control circuit board has at least one through-hole and/or notch allowing an airflow to pass through the control circuit board.

<FIG> shows a blower according to an embodiment of the present invention; the blower is an axial-flow blower, and comprises a blower body <NUM> and a blow pipe <NUM> mounted on the blower body <NUM>. A fan, and a drive unit driving the fan to rotate, are accommodated in the blower body <NUM>. In a state of not being used, a user can remove the blow pipe <NUM> from the blower body <NUM> to reduce storage space. The blower defines an airflow path from an air inlet to an air outlet. The air inlet is formed on the blower body <NUM>, while the air outlet is formed on the blow pipe <NUM>. To facilitate description, in this text, a straight line on which a rotation shaft of the fan in the blower lies is defined as a longitudinal axis, a side facing toward the air outlet is called a far side, and a side facing toward the air inlet is called a near side. In this embodiment, the blow pipe <NUM> is connected to the blower body <NUM> via a snap-fit connector <NUM> located at the near side thereof. It should be understood that other forms of dismantlable connection are also feasible, and are included in the scope of the present invention.

The blower body <NUM> comprises a body housing <NUM> and a casing that defines the airflow path. The body housing <NUM> may consist of two housing halves, to facilitate dismantling. The casing comprises an air-intake-side casing <NUM> and an air-output-side casing <NUM>. A guard <NUM> is attached to a near-side part of the body housing <NUM>, and defines the air inlet of the blower. A protective grille is formed on the guard <NUM> to prevent foreign objects from entering the body housing <NUM>. Advantageously, the grille pattern is designed to help organize disordered external air into a smooth intake airflow.

The blower body <NUM> further comprises a handle <NUM>. In the embodiment shown in <FIG>, the handle <NUM> has a gripping part <NUM> for a user to grip, and a connecting part <NUM> that connects the gripping part <NUM> to the body housing <NUM>. A control button <NUM> is provided on the gripping part <NUM>, to enable the user to operate the blower with a single hand. In an embodiment which is not shown, the connecting part <NUM> is pivotably connected to the body housing <NUM>, to allow the user to adjust the orientation of the handle <NUM> relative to the body housing <NUM>.

The blower body <NUM> further comprises a battery pack installation mechanism <NUM>, for attaching a removable battery pack (not shown in the figures). As battery technology develops, the capacity of battery packs is steadily increasing, and the weight thereof is also increasing accordingly. In this embodiment, the battery pack installation mechanism <NUM> is arranged on the connecting part <NUM> of the handle <NUM>. This arrangement has the advantage that the battery pack is installed directly on the handle <NUM>, closer to the gripping part <NUM>, so the user is able to maintain the orientation of the blower steadily while holding the blower in the hand to perform a job. In other embodiments, the battery pack installation mechanism may be arranged at a lower part or a side of the body housing <NUM>.

<FIG> shows a cross section of the blower. External air enters the blower body <NUM> through the guard <NUM> under the driving action of the fan <NUM>, flows sequentially through the air-intake-side casing <NUM>, the air-output-side casing <NUM> and the blow pipe <NUM>, finally exiting through the air outlet at a far end of the blow pipe <NUM>. Viewed from one side, outer walls <NUM>, <NUM> of the blow pipe <NUM> form an angle with respect to the longitudinal axis L. The angle is preferably less than <NUM> degrees, more preferably less than <NUM> degrees. Too large an angle results in a significant decrease in the area of an air delivery port, and this will increase the force of the airflow at the air delivery port excessively, possibly blowing up heavy objects undesirably, and will also exert high pressure on a blow pipe inner wall close to the air outlet. In this embodiment, the upper-side outer wall <NUM> of the blow pipe <NUM> extends a greater distance along the longitudinal axis L than the lower-side outer wall <NUM>. A bottom support <NUM> is provided at a near-side part of the blow pipe <NUM>, allowing the blower to be placed stably on the ground, and preventing wear to a blow pipe outer surface. Optionally, a protrusion <NUM> is provided at the bottom of a far-end edge of the blow pipe; when the blow pipe is placed on its own, the bottom support <NUM> and the protrusion <NUM> can support the blow pipe <NUM> stably.

In existing blowers, a control unit for controlling fan rotation is generally arranged outside the airflow path, e.g. in the handle <NUM> or in a connection part S of the handle <NUM> and the body housing <NUM>. The control unit must be provided with a means of cooling, because electronic components in the control unit generate heat when the blower is operating. In general, the means of cooling includes providing a metal heat sink on the control unit, and at the same time forming a ventilation port on the body housing close to the control unit. However, the metal heat sink is heavy and will be a burden on the user. In environments where there is no wind or only gentle wind, the amount of air entering the housing through the ventilation port is limited, and is unable to rapidly carry away heat from the metal heat sink.

To overcome the above shortcomings, in the blower shown in <FIG>, a control circuit board <NUM> used as the control unit is arranged in the airflow path, and the control unit is cooled by an airflow generated by the fan <NUM> when rotating. The control circuit board <NUM> may be arranged close to a motor <NUM> of the drive unit, e.g. at an end of the motor <NUM>. In the embodiment of <FIG>, in the airflow direction, the control circuit board <NUM> is located downstream of the motor <NUM>, while the fan <NUM> is located upstream of the motor <NUM>. In other embodiments, the control circuit board <NUM> is located upstream of the motor <NUM>, while the fan <NUM> is located downstream of the motor <NUM>. In the direction of the longitudinal axis L, the control circuit board <NUM> is located substantially in a middle section of the overall length of the blower. Preferably, the ratio d1/d2 of a distance d1 between the control circuit board <NUM> and the air inlet defined by the guard <NUM>, and a distance d2 between the control circuit board <NUM> and the air outlet defined by the blow pipe <NUM>, is <NUM> - <NUM>.

<FIG> shows the air-intake-side casing <NUM> and the air-output-side casing <NUM> which define the airflow path in the blower body <NUM>. A near end of the air-intake-side casing <NUM> is connected to the guard <NUM>, while a far end of the air-output-side casing <NUM> is connected to the blow pipe <NUM>. To expand an air intake region and maintain airflow speed, a near-side part <NUM> of the air-intake-side casing <NUM> is designed to gradually open outward in the near-side direction. The air-intake-side casing <NUM> is substantially cylindrical, and comprises at least one positioning member <NUM>. The positioning member <NUM> may be formed on an outer wall of the air-intake-side casing <NUM>; the positioning member <NUM> engages with a positioning member formed at a corresponding position on the body housing <NUM>, to ensure that the air-intake-side casing <NUM> is installed at a predetermined position of the blower body <NUM>. Similarly, a positioning member <NUM> is also provided on an outer wall of the air-output-side casing <NUM>, and likewise engages with a positioning member formed at a corresponding position on the body housing.

In the embodiment shown in <FIG>, at least a part of the air-output-side casing <NUM> and the air-intake-side casing <NUM> is exposed to the outside environment. In an embodiment which is not shown, the air-intake-side casing <NUM> and the air-output-side casing <NUM> are located inside the body housing <NUM>, with neither being exposed to the outside environment. An elastic positioning member may be provided on the outer wall of the air-intake-side casing <NUM> and/or the air-output-side casing <NUM>. The thickness of the elastic positioning member is slightly greater than a distance between a casing outer wall and a body housing inner wall, such that the elastic positioning member is squeezed between the casing outer wall and the body housing inner wall, thereby positioning the casing in the body housing in a centered fashion, to resist vibration and reduce noise.

<FIG> and <FIG> show the structure of the air-output-side casing <NUM>. The air-output-side casing <NUM> comprises an outer ring <NUM> formed of an outer wall, and an inner ring <NUM> located inside the outer ring <NUM>. The outer ring <NUM> is connected to the inner ring <NUM> via multiple static vanes <NUM>. The multiple static vanes <NUM> are spaced apart circumferentially, and used to guide airflow. The inner ring <NUM> defines a motor casing, with a motor assembly accommodated therein. A far end of the inner ring <NUM> is open, while a near end thereof has a motor mounting frame <NUM>. <FIG> shows that the motor mounting frame <NUM> has a central hole <NUM>, for a motor shaft to pass through. At least one fastener hole <NUM> is formed in the motor mounting frame <NUM>; a fastener (e.g. a screw) can pass through the fastener hole <NUM> to fix the motor to the motor mounting frame <NUM>. Optionally, an opening <NUM> is formed at the periphery of the motor mounting frame <NUM>, and connects the interior of the motor casing with the outside, allowing air to enter or exit the motor casing. A protruding piece <NUM> is also provided on the outer wall of the air-output-side casing <NUM>; a hole in the protruding piece <NUM> is used to receive a fastener which fixes the air-intake-side casing <NUM> to the air-output-side casing <NUM>.

The air-output-side casing <NUM> comprises a tapered flow-guiding body <NUM> which narrows gradually toward the far side. <FIG> shows the tapered flow-guiding body, which is hollow and comprises at least one connector <NUM> extending toward a near end. The connector <NUM> in this embodiment is a hook-like member, and is mated with a connector <NUM> formed at the near side of the inner ring <NUM>, to achieve a fixed connection between the tapered flow-guiding body <NUM> and the inner ring <NUM>. It should be understood that the tapered flow-guiding body <NUM> and the inner ring <NUM> may be connected in any way, or the tapered flow-guiding body <NUM> and the inner ring <NUM> are integrally formed. At least one opening <NUM> is formed in an outer surface of the tapered flow-guiding body <NUM>, and connects the interior of the tapered flow-guiding body <NUM> to the outside, allowing air to enter or exit the tapered flow-guiding body.

The tapered flow-guiding body <NUM> further comprises a wing part <NUM>. The wing part <NUM> has an inner wall <NUM>, an outer wall <NUM> located at a radially outer side of the inner wall <NUM>, and a connecting piece <NUM> which connects the inner wall <NUM> to the outer wall <NUM>. The inner ring <NUM> and outer ring <NUM> of the air-output-side casing <NUM> shown in <FIG> are not completely closed circumferentially, having an inner ring slot <NUM> and an outer ring slot <NUM> respectively. When assembly is complete, the inner wall <NUM> and outer wall <NUM> of the wing part <NUM> enter the inner ring slot <NUM> and outer ring slot <NUM> respectively, and the connecting piece <NUM> is used as a static vane between the outer ring <NUM> and the inner ring <NUM>.

<FIG> shows a cross section of the air-output-side casing <NUM>, with the motor assembly and fan <NUM> accommodated therein. The motor assembly comprises the motor <NUM>, and the control circuit board <NUM> for controlling the operation of the motor. The motor assembly is positioned in the motor casing defined by the inner ring <NUM>. The fan <NUM> is located outside the motor casing and at the near side of the motor <NUM>; and the fan <NUM> is mounted on an output shaft <NUM> of the motor <NUM>. In this embodiment, at least a part of the tapered flow-guiding body <NUM> protrudes beyond the outer ring <NUM>, with the opening <NUM> being formed in part of the protruding part. A near-end edge of the tapered flow-guiding body <NUM> is aligned with a far-end edge of the inner ring <NUM>; when connected together, the tapered flow-guiding body <NUM> and the inner ring <NUM> define a bullet-shaped internal space. It must be explained that although the control circuit board <NUM> shown in <FIG> is located in the inner ring <NUM>, the control circuit board <NUM> may also be arranged at other positions in the internal space.

<FIG> shows the fan and the motor assembly. The fan <NUM> comprises a hub <NUM>, and blades <NUM> extending radially outward from the hub <NUM>. The hub <NUM> is substantially aligned with the inner ring <NUM> of the air-output-side casing <NUM> in the axial direction. A gap between an extremity of the blade <NUM> and an inner wall <NUM> (shown in <FIG>) of the outer ring <NUM> of the air-output-side casing <NUM> is preferably <NUM> - <NUM>, and more preferably <NUM> - <NUM>. Too small a gap might result in the blade scraping the casing inner wall; too large a gap would increase noise, and reduce blowing efficiency. The control circuit board <NUM> in the motor assembly is located at the near side of the motor <NUM>. In this embodiment, the motor <NUM> is an internal rotor motor; a housing of the motor <NUM> comprises a first housing part <NUM> and a second housing part <NUM>, and the control circuit board <NUM> is connected to the second housing part <NUM> in a fixed manner.

<FIG> show the structure of the second housing part <NUM>. The second housing part <NUM> comprises a bottom wall <NUM> covering one end of the motor <NUM>, and a sidewall <NUM> surrounding stator laminations <NUM>. The second housing part <NUM> further comprises two sets of fastener holes. A first set of fastener holes <NUM> is formed in the sidewall <NUM>, being aligned with fastener holes formed in a sidewall of the first housing part <NUM>, and configured to receive fasteners <NUM> (shown in <FIG>) for fixing the first and second housing parts <NUM>, <NUM>. A second set of fastener holes <NUM> is formed in the bottom wall <NUM>, being configured to receive fasteners for fixing the control circuit board <NUM>. In addition to the second set of fastener holes <NUM>, a a cylindrical part <NUM> is also formed on the bottom wall <NUM>, and configured to accommodate a motor bearing. A central through-hole <NUM> in the bottom wall <NUM> allows the motor shaft to pass through.

In the embodiment shown in <FIG>, the first housing part <NUM> and second housing part <NUM> do not completely enclose the motor <NUM>; a portion of the stator laminations <NUM> are not covered by the first housing part <NUM> and second housing part <NUM>. The non-fully-enclosing motor housing makes it easy for air to come into contact with heat-generating components in the motor, thereby increasing the cooling efficiency. Optionally, at least one opening <NUM> is formed in the sidewall <NUM> of the second housing part <NUM>.

The first housing part <NUM> may have substantially the same structure as the second housing part <NUM>, including two sets of fastener holes formed on a sidewall and a bottom wall. The fastener holes in the bottom wall of the first housing part <NUM> are aligned with the fastener holes <NUM> (shown in <FIG>) formed in the motor mounting frame <NUM> of the air-output-side casing <NUM>, and configured to receive fasteners for fixing the motor.

<FIG> shows the control circuit board <NUM>, on which are arranged various electronic components <NUM>, <NUM> for controlling motor operation. Preferably, the shape of the control circuit board <NUM> corresponds to the cross-sectional shape of the motor housing. The ratio of the cross-sectional area of the control circuit board <NUM> to the cross-sectional area of the motor housing is <NUM> - <NUM>, more preferably <NUM> - <NUM>. Although a substantially round control circuit board is shown in the figure, control circuit boards of other shapes are also included in the scope of the present invention. Fastener holes <NUM> are formed in the control circuit board <NUM>, being aligned with the second set of fastener holes <NUM> formed in the bottom wall <NUM> of the second housing part <NUM>. Preferably, at least one through-hole is also formed in the control circuit board, e.g. a through-hole <NUM> located in the center and a through-hole <NUM> close to an edge, or a notch is formed in an edge of the control circuit board. These through-holes or notches allow air to pass through the control circuit board <NUM> and carry away heat generated by the electronic components during operation. In addition, the through-hole <NUM> located in the center may also accommodate the motor shaft.

Returning to <FIG>, this shows flow paths of air when the blower is operating. An airflow passes through an annular region between the inner ring <NUM> and the outer ring <NUM> under the action of the fan, then exits the air-output-side casing <NUM> under the guiding action of the tapered flow-guiding body <NUM> and enters the blow pipe <NUM>. In this embodiment, the inner wall <NUM> of the wing part <NUM> of the tapered flow-guiding body <NUM> does not completely occupy the inner ring slot <NUM> in the inner ring <NUM> of the air-output-side casing <NUM>. The part of the inner ring slot <NUM> which is not occupied by the inner wall <NUM> forms an inner ring hole <NUM>, which connects the annular region with the inner ring <NUM>. Thus, when the blower is operating, a portion of the indrawn air enters the motor casing through the inner ring hole <NUM>, and carries away heat generated by the motor components.

Similarly, the outer wall <NUM> of the wing part <NUM> does not completely occupy the outer ring slot <NUM> in the outer ring <NUM>. The part of the outer ring slot <NUM> which is not occupied by the outer wall <NUM> forms an outer ring hole <NUM>, which connects the air-output-side casing <NUM> with the body housing <NUM>. Preferably, the outer ring hole <NUM> and inner ring hole <NUM> are aligned in a vertical direction. An electric wire connected to the control button on the handle <NUM> can pass through the outer ring hole <NUM> and inner ring hole <NUM> to reach the control circuit board <NUM>.

Hereinbelow, the air which exits the air-output-side casing <NUM> through the annular region is referred to as a main air flow, while the air which enters the motor casing through the inner ring hole <NUM> is referred to as a cooling air flow, to make it easier to distinguish between the two. In order to make full use of the cooling air flow, the control circuit board <NUM> is positioned close to the motor <NUM>, preferably downstream of the inner ring hole <NUM>, so that the cooling air flow can also cool the control circuit board <NUM>. Since the control circuit board <NUM> is located in the inner ring <NUM> of the air-output-side casing <NUM>, it will not affect the main air flow.

As can be seen from <FIG>, the control circuit board <NUM> is arranged substantially transversely to the longitudinal axis, i.e. transversely to the flow direction of the cooling air flow. This manner of arrangement increases the area of contact between the control circuit board <NUM> and the cooling air flow. Furthermore, due to the blocking action of the control circuit board <NUM>, the cooling air flow is not able to exit the inner ring <NUM> rapidly, which increases the time of contact between the cooling air flow and the control circuit board <NUM>. The ratio of the cross-sectional area of the control circuit board <NUM> to the area enclosed by the inner ring <NUM> is preferably <NUM> - <NUM>, more preferably <NUM> - <NUM>. The ratio of the cross-sectional area of the control circuit board <NUM> to the area enclosed by the outer ring <NUM> is <NUM> - <NUM>, more preferably <NUM> - <NUM>. As a new cooling air flow enters the inner ring <NUM>, the original cooling air flow exits the inner ring <NUM> through the through-hole in the control circuit board <NUM> and a gap between the control circuit board <NUM> and the inner ring <NUM>, and enters the tapered flow-guiding body <NUM>.

<FIG> is a view of an end face of the tapered flow-guiding body <NUM>. Viewed in a direction from the near side to the far side, three openings <NUM> in the tapered flow-guiding body <NUM> are spaced apart circumferentially. Each opening <NUM> is enclosed by two arcs <NUM>, <NUM> and two sides. The two arcs <NUM>, <NUM> are arc sections on two circles of different radii centered at the center of an extremity <NUM> of the tapered flow-guiding body <NUM>. The openings <NUM> enable the cooling air flow to rapidly enter the blow pipe <NUM> through the tapered flow-guiding body <NUM>, thereby carrying away heat generated by the motor <NUM> and the control circuit board <NUM>. It should be understood that the number, shape and manner of arrangement of the openings may be varied; for example, round or annular openings may be chosen. In other embodiments, an opening may also be formed at the extremity <NUM> of the tapered flow-guiding body. In view of the fact that the cooling air flow will mix with the main air flow after exiting the tapered flow-guiding body <NUM>, the shape and arrangement of the openings should be designed in such a way that interference to the main air flow from the cooling air flow is avoided as much as possible. The manner of arrangement of the openings shown in <FIG> is able to achieve this result.

Claim 1:
A blower, comprising:
a blower body (<NUM>), having accommodated therein a fan (<NUM>) and a drive unit, a rotation shaft of the fan defining a longitudinal axis, and the blower body defining an air inlet;
a blow pipe (<NUM>), attached to the blower body (<NUM>) and extending along the longitudinal axis, the blow pipe (<NUM>) defining an air outlet;
a control unit, for controlling operation of the drive unit, wherein the drive unit comprises a motor (<NUM>) and the control unit comprises a control circuit board (<NUM>) located at an end of the motor (<NUM>); preferably, in an airflow direction, one of the control circuit board (<NUM>) and the fan (<NUM>) is located downstream of the motor (<NUM>) while the other is located upstream of the motor (<NUM>);
wherein the blower defines an airflow path extending from the air inlet to the air outlet, the control unit being at least partially located in the airflow path, such that when the blower is operating, at least a portion of an airflow entering the air inlet cools the control unit and is then discharged through the air outlet;
wherein the blower body comprises a casing in which the fan (<NUM>), motor (<NUM>) and control circuit board (<NUM>) are located, and wherein the casing comprises a hollow tapered flow-guiding body (<NUM>), the tapered flow-guiding body (<NUM>) having an opening (<NUM>) formed in a surface and/or an extremity of the tapered flow-guiding body (<NUM>);
wherein the casing comprises an outer ring (<NUM>) and an inner ring (<NUM>), the tapered flow-guiding body (<NUM>) being connected to the inner ring (<NUM>), and the control circuit board (<NUM>) being located in a space defined by the tapered flow-guiding body (<NUM>) and the inner ring (<NUM>);
characterized in that the tapered flow-guiding body (<NUM>) further comprises a wing part (<NUM>), the wing part (<NUM>) having an inner wall (<NUM>), an outer wall (<NUM>) located at a radially outer side of the inner wall (<NUM>), and a connecting part (<NUM>) which connects the inner wall (<NUM>) to the outer wall (<NUM>); and an inner ring slot (<NUM>) and an outer ring slot (<NUM>) which mate with the inner wall (<NUM>) and the outer wall (<NUM>) are formed in the inner ring (<NUM>) and the outer ring (<NUM>) of the casing respectively.