The present invention relates to a centrifugal fan, and in particular, relates to a centrifugal fan in which when a connector pin is soldered to a circuit board, and whether or not soldering was performed properly can be visually inspected by viewing the back side of the circuit board.
Conventionally, as this kind of centrifugal fan, a centrifugal fan disclosed in the Patent document 1 is known, for example. In the centrifugal fan of the Patent document 1, during formation of a lower casing 140, a connector housing 161 is formed by integrally forming with resin at the same time. A connector pin 162 is attached inside the connector housing 161, and the connector pin 162 is joined to a wiring pattern of a circuit board 132 arranged at a concave portion 141 of the lower casing 140 by soldering.
Patent document 1 is Japanese Unexamined Patent Application Publication No. 2018-200048 (
Generally, a connector pin 162 is soldered to a through hole formed in a circuit board 132. Due to fused solder, a solder fillet (front fillet) is formed at a corner portion of surface of the circuit board 132 and the connector pin 162. At the same time, part of the fused solder is filled in the through hole, travels to a back side of the circuit board 132 via the through hole, and forms a solder fillet (back fillet), thereby strongly affixing the connector pin 162 to the circuit board 132. Since soldering conditions have an effect on affixing strength of the connector pin 162 and on performance, it is desirable to perform visual inspection of whether or not soldering was performed properly.
However, in the centrifugal fan of Patent document 1, since the connector pin 162 is soldered to the wiring pattern of the circuit board 132 arranged on a bottom surface of the concave portion 141 of the lower casing 140, good or inferior soldering conditions can be visually inspected from a front side (upper surface side) of the circuit board 132; however, it is difficult to visually inspect for good or inferior soldering conditions on the back side of the circuit board 132.
In view of the above circumstances, an object of the present invention is to provide a centrifugal fan in which whether or not soldering was performed properly can be visually inspected at the back side of the circuit board.
The centrifugal fan of the present invention includes a primary casing, a secondary casing cooperating with the primary casing so as to form a casing, an impeller rotatably arranged in the casing, a motor rotating the impeller and a circuit board arranged in the secondary casing, the secondary casing includes a connector housing having an opening portion at lateral side thereof and a connector pin embedded inside, in which one end of the connector pin protrudes inside the connector housing, and the other end of the connector pin protrudes from a bottom surface of the secondary casing, penetrates the circuit board, and is soldered to the circuit board, thereby forming a solder fillet between the front and back surface of the circuit board and the connector pin; there is a gap between the secondary casing and the part of the circuit board where the connector pin penetrates, and a through hole for visual inspection is arranged in a bottom wall portion of the secondary casing so as to see the fillet formed between the back surface of the circuit board and the connector pin.
According to the centrifugal fan of the present invention, since the through hole for visual inspection of which one opening portion is close to the solder fillet of the connector pin existing in the gap and the solder fillet is seen through from the other opening portion is arranged in a bottom wall portion of the secondary casing, the solder fillet can be seen from the secondary casing side through the through hole, and therefore, good or inferior condition of soldering on the back side of the circuit board can be visually inspected.
Here, a surface of the through hole close to the solder fillet can be inclined to a plane orthogonal to the circuit board. In this embodiment, since amount of the secondary casing can be maintained in the inclined portion, the strength can be increased.
An embodiment can be selected in which multiple convex portions protruding to the primary casing side are arranged on the bottom surface of the secondary casing, and the circuit board is supported by the convex portions. In this embodiment, since a gap between the secondary casing and the part of the circuit board where a connector pin penetrates can be wider, visual inspection of the back fillet may be facilitated.
An embodiment can be selected in which a through hole is formed penetrating both the convex portions and the secondary casing, an insulator which is attached on a stator core and is wound in a coil is arranged on the motor, and a pin penetrating the though hole and protruding from the surface of the secondary casing is arranged on the insulator, and the protruding end portion of the pin is swaged so as to be affixed on the surface of the secondary casing. In this embodiment, since thickness along an axial direction of the through hole can be greater, strength around the through hole can be increased.
An embodiment can be selected in which a rib is formed at the bottom surface of the secondary casing made of resin, and the convex portion made of resin and the rib are overlapped in plan view and integrally fused and formed so that the convex portion protrudes from the rib to the primary casing side. In this embodiment, since the convex portion and the rib are overlapped and integrally formed, the rib is reinforced.
It is desirable that an opening portion outside the through hole for visual inspection is closed by a face plate or the like after the inspection of the solder fillet. In this way, dust, water, oil and the like are prevented from entering inside the centrifugal fan.
According to the present invention, a centrifugal fan is provided, in which good or inferior condition of soldering at the back side of the circuit board can be visually inspected.
The upper casing 110 is made of resin, and an air inlet 111 is formed at a center thereof. Furthermore, at four locations along an outer circumference of the upper casing 110, a flange 112, being approximately triangular and projecting to a radially outer direction, is formed. As shown in
On the flange 112, a support pillar 140 extending downwardly in
In this embodiment, a through hole 112a is formed in the flange 112 and the support pillar 140, a lower end surface of the support pillar 140 contacts a bottom surface of the lower casing 130, a screw (not shown) is inserted in a through hole 130a (shown only in
A portion of the side surface of the casing 150 excluding the support pillar 140 is a gap between the upper casing 110 and the lower casing 130, and this gap portion corresponds to an air outlet 111a. In addition, an impeller 120 made of resin is contained in a rotatable condition between the upper casing 110 and the lower casing 130.
The impeller 120 consists of a hub 121 having a cup shape, and multiple blades 122 which incline from around the outer circumference of the upper surface of the hub 121 to a radial direction and which extend outwardly. All of the blades 122 have the same shape, and they are arranged at equal spacing along a circumferential direction. That is, the blades 122 rotate clockwise in
A ring shaped yoke (not shown) and a ring shaped magnet 128 (shown only in
An insulator 162, which is made of resin and which has an upward and downward half-divided structure, is attached on the stator core 161, and a stator coil 163 is wound on each salient pole of the stator core 161 via the insulator 162.
The lower casing 130 is made of resin and a dish shaped structure and has a concave portion 134. A circuit board 135 is contained in the concave portion 134. The circuit board 135 includes a driving circuit supplying a driving current to the stator coil 163. Structures of the circuit board 135 and therearound are explained as follows in detail.
A cylindrical portion 132 protruding upwardly is formed at a central part of the lower casing 130. In the cylindrical portion 132, a bearing holder (bearing holding portion) 170 which is made of metal (for example, brass) and is cylindrical, is affixed by an insert molding. The abovementioned stator core 161 is attached to the outer circumference of the bearing holder 170. A step portion 170a (see
The stator core 161, the insulator 162, and the stator coil 163 form a stator 160. Furthermore, a shaft 125, the ring shaped yoke (not shown), and the magnet 128 form a rotor 129. In this way, the stator 160 and the rotor 129 form an outer rotor type brushless DC motor.
As shown in
The structure around the circuit board 135 is explained with reference to
As shown in
A through hole 138a which penetrates to the back surface of the lower casing 130 is formed at the convex portion 138. In addition, the circuit board 135 is supported by the convex portion 138, and the radial rib 136 together with the concentric rib 137 have a gap 139 between them and the circuit board 135.
On the other hand, as shown in
As shown in
At the bottom wall portion of the lower casing 130, a through hole for visual inspection 193 is formed close to the connector pin 192. The through hole for visual inspection 193 is formed by a perpendicular surface 193a which is perpendicular to the circuit board 135, an inclined surface 193b which is inclined to the perpendicular surface 193a, and a side surface 193c which is perpendicular to the inclined surface 193b. In this case, the inclined surface 193b directs and descends to a direction opposite to the connector pin 192 side.
An opening portion 193d which is inside the through hole for visual inspection 193 is close to the back fillet 195b, and the back fillet 195b is seen through from an opening portion 193e which is outside the through hole. It should be noted that the reference numeral 196 is a rib for reinforcing the connector housing 190, and the reference numeral 197 is a triangular rib.
As shown in
Since the back fillet 195b and the front fillet 195a sandwich the circuit board 135 so that the connector pin 192 is strongly affixed to the circuit board 135, performance of the connector pin 192 can be maintained. It should be noted that inspection of the front fillet 195a is performed from the upper side of the lower casing 130. In this way, in the above embodiment, since it is made so that it is possible to see through from the opening portion 193b side which is outside the through hole for visual inspection 193 to the back fillet 195b of the connector pin 192, the solder fillet (back fillet) 195b can be visually inspected, and good or inferior condition of soldering at the back side of the circuit board 135 can be visually inspected. It should be noted that the opening portion 193e outside the through hole for visual inspection 193 is closed by a face plate or the like after finishing the inspection of the solder fillet (back fillet) 195b.
In the above embodiment, since the inclined surface 193b which directs and descends to a direction opposite to the connector pin 192 side is arranged in the through hole for visual inspection 193, amount of the lower casing is maintained in the inclined portion, and the strength is increased.
In the above embodiment, since the multiple convex portions 138 upwardly protruding are arranged on the bottom surface of the lower casing 138, and the circuit board 135 is supported by the convex portions 138, a gap between the lower casing 130 and the part of the circuit board 135 where the connector pin 192 penetrates can be wider, visual inspection of the back fillet may be facilitated.
In the above embodiment, the through hole 138a is formed penetrating both of the convex portion 138 and the lower casing 130, and on the other hand, the resin pin 162a penetrating the through hole 138a and protruding from the back surface of the lower casing 130 is formed on the insulator 162 and the end portion of the resin pin 162a protruding is swaged so as to be affixed to the back surface of the lower casing 130. Therefore, the thickness of the through hole 138a along the axial direction is large, and therefore, strength around the through hole 138a is higher.
In the above embodiment, since the radial rib 136 and the concentric rib 137 are formed on the bottom surface of the lower casing 130, and the convex portion 138 overlaps the ribs 136 and 137 in plan view, and they are integrally fused and formed, the strength of the ribs 136 and 137 is increased.
(1) In the above embodiment, a cross-sectional shape of the through hole for visual inspection 193 is rectangle. Alternatively, it can be ellipse or oval. In addition, a through hole for visual inspection having circular or rectangular cross-section or the like can be formed at a position corresponding to each of the connector pins 192.
(2) In the above embodiment, the rotor magnet 128 is attached to the hub 121 of the impeller 120. Alternatively, the present invention may be applied to a structure in which a metallic bush (for example, made of brass) is affixed to the shaft 125 by press fitting or the like, a yoke made of a soft magnetic material (for example, iron) is attached to the bush by swaging or the like, the rotor magnet is attached to the yoke, and the yoke is attached to the impeller.
The present invention may be used in a technical field of a centrifugal fan, such as a blower device used for cooling, ventilation, air conditioning of home electric appliances, office automation equipment and industrial equipment, and vehicle equipment, and the like.
100: centrifugal fan, 110 upper casing (primary casing), 111: air inlet, 111a: air outlet, 112: flange, 112a: through hole, 113: radial rib, 114 concentric rib, 115: radial rib, 116: concentric rib, 120: impeller, 121: hub, 122: blade, 125: shaft, 128: magnet, 129: rotor, 130: lower casing (secondary casing), 130a: through hole, 132: cylindrical portion, 134: concave portion, 135: circuit board, 135a: through hole, 136: radial rib, 136a: triangular rib, 137: concentric rib, 138: convex portion, 138a: through hole, 139: gap, 140: support pillar, 150: casing, 160: stator, 161: stator core, 162: insulator, 162a: resin pin, 163 stator coil, 170: bearing holder, 170a: step portion, 181: ball bearing, 182: ball bearing, 190: connector housing, 191: opening portion, 192: connector pin, 193: through hole for visual inspection, 193a: perpendicular surface, 193b: inclined surface, 193c: side surface, 193d: inner opening portion, 193e: outer opening portion, 195a: front fillet, 195b: back fillet, 196: rib, 197: rib.
Number | Date | Country | Kind |
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2019-146166 | Aug 2019 | JP | national |