Electric unit including a motor, control unit, cooling fan, and a casing, and an operating machine equipped with the electric unit

An electric unit is provided with: a motor having a stator and a rotor; a control unit that controls the motor; and a cooling fan that generates cooling wind for cooling the motor and the control unit. The control unit is provided in the upstream of the stator in a cooling flow channel for circulating the cooling wind. The cooling fan is provided to be positioned in the downstream of the motor in the cooling flow channel, the cooling fan generating the cooling wind by drawing air.

TECHNICAL FIELD

The present invention relates to an electric unit equipped with a motor and a control unit adapted to control the motor.

BACKGROUND ART

An electric unit of this type is incorporated in a lawn mower, for example. In Japanese Patent No. 3776773, an electric lawn mower is proposed, which is equipped with a battery, a motor driven by electrical power from the battery, and a control unit for controlling the motor. With such an electric lawn mower, negative pressure is generated by rotation of a cutter blade provided on a shaft of the motor, outside air is taken into the cover as cooling air, and the cooling air is caused to flow sequentially in order of the battery, the control unit, and the electric motor, thereby cooling the battery, the control unit, and the electric motor.

Further, in Japanese Laid-Open Patent Publication No. 2015-084699, a pruning machine is disclosed in which outside air (cooling air) is guided to a motor by a cooling fan, which is fixed to the shaft of the motor, in order to cool the motor.

SUMMARY OF INVENTION

However, in Japanese Patent No. 3776773, since the cooling air is generated using rotation of the cutter blade for the purpose of cutting grass, for example, in the case that the amount of generated heat of the motor is comparatively large, cases may occur in which the electric motor cannot be sufficiently cooled.

Further, in Japanese Laid-Open Patent Publication No. 2015-084699, the arrangement of a control unit for controlling the motor is not described. Therefore, there is a concern that a control unit therein cannot be effectively cooled in relation to the motor.

The present invention has been devised taking into consideration the aforementioned problems, and has the object of providing an electric unit which is capable of effectively cooling a control unit and a motor.

In order to achieve the above object, an electric unit according to the present invention includes a motor having a stator and a rotor, a control unit configured to control the motor, and a cooling fan configured to generate cooling air for cooling the motor and the control unit, wherein the control unit is disposed on a more upstream side than the stator in a cooling flow path through which the cooling air flows.

In accordance with such a configuration, the cooling air generated by the cooling fan can be guided to the stator after having flowed to the control unit, which is lower in temperature than the stator. Consequently, the control unit and the motor can be effectively cooled.

In the above-described electric unit, the cooling fan may be disposed in a manner so as to be positioned on a more downstream side than the motor in the cooling flow path, and may generate the cooling air by drawing in air.

In accordance with such a configuration, it is possible for the cooling air to more smoothly flow toward the control unit and the motor, in comparison with a case in which, in the cooling flow path, the cooling fan is disposed on a more upstream side than the control unit is, in order to blow air.

In the above-described electric unit, there may further be provided a casing in which the motor is accommodated, the casing having an intake port and a discharge port.

In accordance with such a configuration, the motor can be protected by the casing. Further, the cooling air that has flowed into the casing from the intake port can be guided toward the control unit and the motor, and thereafter, flow out to the exterior of the casing from the discharge port.

In the above-described electric unit, the motor may be configured as an outer rotor type motor, the rotor and the control unit may face toward each other with a gap therebetween, and the intake port may be directed toward the gap.

In accordance with such a configuration, since the cooling air that flows in from the intake port can be uniformly guided to the gap between the control unit and the rotor, the control unit and the stator can be cooled in a uniform manner.

In the above-described electric unit, the cooling fan may be disposed on an opposite side of the motor from the control unit, and the discharge port may be disposed in the vicinity of the cooling fan.

In accordance with such a configuration, the cooling air that flows into the casing from the intake port can be made to flow smoothly to the exterior of the casing from the discharge port via the control unit and the motor.

In the above-described electric unit, a rotating body is configured to be connected to a shaft of the motor, and the electric unit may further include a shielding unit configured to block inflow of wind, which is generated by rotation of the rotating body, into the cooling fan.

In accordance with such a configuration, by the shielding unit, it is possible to suppress a change in the air volume, the air direction, etc., of the cooling air due to the wind generated by rotation of the rotating body. Consequently, it is possible to stably cool the control unit and the motor. Further, it is possible to suppress foreign matter from flowing into the cooling fan together with the wind generated by rotation of the rotating body.

In the above-described electric unit, there may further be provided a guide wall configured to guide the cooling air toward the discharge port.

In accordance with such a configuration, the cooling fan can be rotated in an efficient manner. Further, the cooling air inside the casing can be discharged smoothly from the discharge port.

In the above-described electric unit, there may further be provided a battery configured to supply electrical power to the motor, wherein the battery is disposed on a more upstream side than the control unit in the cooling flow path.

In accordance with such a configuration, even in the case that the temperature of the battery becomes comparatively high, the battery, the control unit, and the motor can be effectively cooled.

According to the present invention, because the control unit is disposed on a more upstream side than the stator in the cooling flow path of the cooling air that is generated by the cooling fan, the control unit and the motor can be effectively cooled.

DESCRIPTION OF EMBODIMENTS

Preferred embodiments of an electric unit according to the present invention in relation to operating machines in which the electric unit is incorporated will be described below with reference to the accompanying drawings.

An operating machine equipped with the electric unit10A according to the present embodiment shown inFIG.1is a walking type of lawn mower12A for cutting grass. InFIGS.1to5, the arrow Fr indicates a front direction of the lawn mower12A (which is the same as the front direction as viewed from the perspective of an operator), and the arrow Rr indicates a rear direction of the lawn mower12A (which is the same as the rear direction as viewed from the perspective of the operator).

As shown inFIGS.1and2, the lawn mower12A is equipped with a housing14constituting a machine body, left and right front wheels16arranged at a front portion of the housing14, left and right rear wheels18arranged at a rear portion of the housing14, a lawn mower cutter blade20accommodated inside the housing14, a cover member22disposed on a top portion of the housing14and in which the electric unit10A is accommodated, and an operating handle24which is extended in a rearward direction from the housing14.

The lawn mower12A is an electric lawn mower which is driven by electricity. More specifically, in the lawn mower12A, the cutter blade20is made to rotate by the electric unit10A, thereby mowing grass that exists below the lawn mower12A. At this time, a flow of air (circling wind), which rotates in the same direction as the direction of rotation of the cutter blade20, is generated in the housing14. Additionally, by the circling wind, the grass that is cut by the cutter blade20is blown into and is accommodated in a cut grass accommodating body28through a cut grass conveyance passage26that is formed in the housing14. In the housing14, only a portion thereof facing toward the ground (lawn) is opened in a downward direction.

As shown inFIG.2, on a rear portion of the cover member22, an air introducing unit30is provided through which air is introduced into the interior of the cover member22. An opening30aof the air introducing unit30is oriented downward. Consequently, it is possible to prevent foreign matter such as grass or the like from entering into the cover member22via the air introducing unit30.

On a front portion of the cover member22, an air lead-out unit32is provided for guiding the air inside the cover member22to the exterior. The air lead-out unit32is configured by forming in a vertical direction a plurality of slits, which are extended in a lateral (left-right) direction of the lawn mower12A (seeFIGS.1and2). Owing to this feature, it is possible to prevent exhaust from the cover member22from impinging on the operator. However, the air introducing unit30and the air lead-out unit32are not limited to the forms described above, and may be provided in any manner with respect to the cover member22.

InFIG.2, the electric unit10A is equipped with an electric unit main body34and a battery36. As shown inFIGS.2to4, the electric unit main body34includes a casing38, a motor40accommodated in the casing38, a control unit42adapted to control the motor40, a cooling fan44that generates cooling air (air) for cooling the motor40and the control unit42, and a shielding member46(shielding unit) provided on the casing38.

The casing38includes a first casing48on which the control unit42is supported, an intake duct50provided in the first casing48, and a cylindrically shaped second casing52in which a stator84of the motor40is supported. As shown inFIGS.2and4, the first casing48includes a bottom portion54connected to the second casing52, and side portions56disposed on the bottom portion54. A circular hole58that communicates with the interior of the second casing52is formed in the center of the bottom portion54. The side portions56are provided on three sides out of the four sides that constitute the outer shape of the bottom portion54. On inner surfaces of the side portions56, projecting portions60are formed, which support the control unit42in a state of being separated from the bottom portion54.

The intake duct50is a square annular-shaped member constituting an intake port51. The intake duct50is attached to a part of the bottom portion54where the side portions56are not provided. A seal member62is provided between the intake duct50and the first casing48. A filter member66is mounted via a seal member64on an opposite side of the intake duct50from the first casing48(rearwardly of the lawn mower12A). The intake port51communicates with an inner hole of the air introducing unit30via the filter member66. The filter member66removes foreign matter such as moisture and dust or the like contained within the air that is guided from the air introducing unit30.

The second casing52includes an outer circumferential wall portion68formed in a cylindrical shape, a supporting wall portion70provided on an inner circumferential surface of the outer circumferential wall portion68, and attachment sections72provided on the outer circumferential wall portion68. One end (an upper end) of the outer circumferential wall portion68is fixed to the bottom portion54of the first casing48by a plurality of bolts74(seeFIG.4). The supporting wall portion70is positioned in a middle part in the axial direction of the outer circumferential wall portion68. An insertion hole70athrough which a shaft88of the motor40is inserted is formed in the supporting wall portion70. Further, in the supporting wall portion70, communication holes78(seeFIG.2) are formed that enable communication mutually between a first space52alocated above the supporting wall portion70(on a side of the first casing48), and a second space52blocated below the supporting wall portion70(on a side opposite from the first casing48) within the second casing52.

As shown inFIGS.2to4, a plurality of bolts80(seeFIG.2) for fixing the second casing52to the cover member22are threaded into the attachment sections72. A discharge port82(seeFIG.2) through which the air inside the second casing52is discharged to the exterior is provided in a lower portion of the second casing52.

InFIGS.2and4, the motor40is configured as an outer rotor type motor. The motor40includes a stator84that is fixed to the supporting wall portion70of the second casing52, a rotor86disposed rotatably with respect to the stator84, and a shaft88that is fixed to the rotor86. The motor40is arranged in a manner so that the axis of the shaft88extends in a vertical direction.

The stator84is configured in an annular shape, and is disposed in the first space52aof the second casing52. The stator84includes a stator core90in which a plurality of steel plates are stacked, insulators92disposed at the respective poles of the stator core90, and a plurality of stator coils94wound around the insulators92.

The rotor86includes a bottomed cylindrical rotor cup96, and a plurality of permanent magnets98disposed on the rotor cup96. The rotor cup96covers the outer circumferential surface of the stator core90, and covers one surface (an upper surface) of the stator core90in the axial direction. A gap S1through which air is capable of flowing is formed between the rotor cup96and the outer circumferential wall portion68. The plurality of permanent magnets98are provided in a circumferential direction on the inner circumferential surface of the rotor cup96. A plurality of through holes100through which air is introduced into the rotor cup96are formed on an upper surface of the rotor cup96.

InFIG.2, a boss member102, which is disposed at one end (an upper end) of the shaft88, is fixed by a rivet104to a central portion of the rotor cup96. The boss member102is fixed to the shaft88by a nut106.

The shaft88extends in a vertical direction in a manner so as to pass through the insertion hole70aof the supporting wall portion70, and an insertion hole46aof the shielding member46. The shaft88is rotatably supported by bearings105,107, which are fixed to wall surfaces that constitute the insertion holes46a,70a. The cutter blade20, which is a rotating body, is connected via a blade holder108to another end (a lower end) of the shaft88.

The blade holder108is attached to a central portion of the cutter blade20, together with being coaxially connected to the shaft88at the lower end of the shaft88. The cutter blade20includes a blade main body112that extends in a direction perpendicular to the axis of the shaft88, together with blade portions110being provided at front edges in the direction of rotation thereof, and flaps114being attached to the blade main body112in a manner so that a flap angle thereof can be changed. The blade main body112is an elongated member (a so-called bar blade) in the form of a plate.

The control unit42and the rotor86are disposed in facing relation to each other with a gap S2therebetween. The control unit42is a heat generating element having a non-illustrated control circuit board. The control unit42is spaced from the bottom portion54of the first casing48. The intake port51is directed toward the gap S2formed between the control unit42and the motor40.

The cooling fan44is disposed in the second space52bof the second casing52. Stated otherwise, the cooling fan44is positioned on an opposite side of the motor40from the control unit42(i.e., below the stator84). More specifically, the cooling fan44is disposed in a dead space below the stator84. Consequently, by effectively utilizing the dead space, it is possible to reduce the size of the electric unit10A as well as to reduce the number of parts thereof.

The cooling fan44is fixed coaxially with respect to the shaft88. Therefore, the cooling fan44rotates integrally with the shaft88. The cooling fan44is constituted as a so-called drawing-in type of cooling fan44. By rotation thereof, the cooling fan44draws in air from the intake port51, and thereby generates cooling air.

The cooling fan44is disposed so as to be positioned on a more downstream side than the motor40in the cooling flow path of the cooling air that flows from the intake port51toward the discharge port82. In this case, the control unit42is disposed on a more upstream side than the stator84in the cooling flow path. The discharge port82is positioned in the vicinity of the cooling fan44. More specifically, the discharge port82is located radially outward of the cooling fan44.

The shielding member46is fixed to the second casing52by a plurality of bolts116(seeFIG.4), so as to cover an opening on a lower side of the second casing52(on an opposite side thereof from the control unit42). Owing to this feature, the shielding member46prevents wind (circling wind) generated by rotation of the cutter blade20from flowing into the cooling fan44. In a central portion of the shielding member46, an insertion hole46ais formed through which the shaft88is inserted, and the bearing107is provided in the insertion hole46a. InFIGS.2,4, and6, on a surface (upper surface) of the shielding member46exposed to the second space52b, a guide wall118is provided for guiding the air (cooling air) drawn into the cooling fan44to the discharge port82.

The guide wall118extends radially outward in a gradually widening manner in the circumferential direction around the axis of the shaft88. Stated otherwise, the guide wall118extends in a spiral shape. Moreover, a guide wall119having the same shape as the guide wall118(a spirally extending shape) is provided in a portion of the second casing52(on the side of the shielding member46) below the supporting wall portion70.

The battery36is a battery for supplying electrical power to the motor40and the control unit42. The battery36is disposed between the second casing52and the air lead-out unit32in the interior of the cover member22.

Next, operations of the electric unit10A, which is configured as described above, will be explained in relation to operations of the lawn mower12A.

InFIG.5, when the rotor86rotates under the action of the battery36, the cutter blade20connected to the shaft88rotates, and grass growing on the lawn directly below the lawn mower12A is cut by the cutter blade20. The lawn grass which has been cut (cut grass) is delivered into the cut grass accommodating body28via the cut grass conveyance passage26formed inside the housing14, by the circling wind that is generated accompanying rotation of the cutter blade20.

At this time, the battery36, the control unit42, and the motor40generate heat. More specifically, the control unit42becomes lower in temperature than the stator84, while being higher in temperature than the battery36. Stated otherwise, the stator84becomes highest in temperature. Further, when the cooling fan44is rotated by rotation of the shaft88, outside air (air), which is guided from the air introducing unit30of the cover member22, is drawn into the intake port51via the filter member66. At this time, moisture, dust and the like contained within the air are removed by the filter member66.

In addition, clean air (cooling air) that is guided via the filter member66into the intake port51flows through the gap S2between the control unit42and the rotor86. Consequently, the control unit42and the rotor86are cooled substantially at the same time by the cooling air. Then, the cooling air that has cooled the control unit42is guided into the first space52aof the second casing52.

The cooling air that was guided into the first space52apasses through the through holes100of the rotor cup96, flows between the stator84and the rotor86, and the cooling air flows into the interior of the stator84(between the respective stator coils94that constitute the stator84). Stated otherwise, the cooling air directly cools the stator coils94which generate the majority of heat inside the motor40. Consequently, the interior of the motor40(the stator84) is effectively cooled by the cooling air.

Further, the cooling air that was guided into the first space52aflows downwardly through the gap S1between the rotor cup96and the outer circumferential wall portion68of the second casing52. Consequently, it is possible to effectively reduce the flow path resistance of the cooling air, and the flow rate of the cooling air that flows to the control unit42can be increased. Further, the outer side (rotor86) of the motor40is effectively cooled by the cooling air.

The cooling air that has flowed respectively through the interior and the exterior of the rotor86merges together downwardly of the stator84, and flows into the second space52bvia the communication holes78of the supporting wall portion70. The cooling air that has flowed into the second space52bis made to flow radially outward by the cooling fan44, flows in a spiral shape along the guide wall118, and is discharged from the discharge port82to the exterior of the casing38.

The cooling air that is discharged to the exterior of the casing38flows along the cover member22toward the front of the lawn mower12A, and is led outside of the cover member22from the air lead-out unit32. Moreover, the battery36is cooled naturally, not by the cooling air but by dissipation of heat therefrom.

In this case, the electric unit10A according to the present embodiment exhibits the following advantageous effects.

In the electric unit10A, the control unit42is disposed on a more upstream side than the stator84of the motor40in the cooling flow path through which the cooling air generated by the cooling fan44flows. In accordance with this feature, the cooling air generated by the cooling fan44can be guided to the stator84after having flowed to the control unit42, which is lower in temperature than the stator84. Thus, the control unit42and the motor40can be effectively cooled.

The cooling fan44is disposed in a manner so as to be positioned on a more downstream side than the motor40in the cooling flow path, and generates the cooling air by drawing in air. Therefore, it is possible for the cooling air to more smoothly flow toward the control unit42and the motor40, in comparison with a case in which the cooling fan44is disposed on a more upstream side than the control unit42in the cooling flow path in order to blow air.

The casing38accommodates the motor40, and the intake port51and the discharge port82are formed therein. In accordance with this feature, the motor40can be protected by the casing38. Further, the cooling air that has flowed into the casing38from the intake port51can be guided to the control unit42and the motor40, and thereafter, flow out to the exterior of the casing from the discharge port82.

The motor40is configured as an outer rotor type motor. In addition, the rotor86and the control unit42are disposed in facing relation to each other with the gap S2therebetween, and the intake port51is directed toward the gap S2. In accordance with this feature, since the cooling air that has flowed in from the intake port51can be uniformly guided to the gap S2between the control unit42and the motor40, the control unit42and the stator84can be cooled in a uniform manner.

The cooling fan44is disposed on an opposite side of the motor40from the control unit42, and the discharge port82is disposed in the vicinity of the cooling fan44. In accordance with this feature, the cooling air that flows into the casing38from the intake port51can be made to flow smoothly to the exterior of the casing38from the discharge port82via the control unit42and the motor40.

The cutter blade20, which is a rotating body, is connected to the shaft88of the motor40. In addition, the shielding member46prevents the circling wind generated by rotation of the cutter blade20from flowing into the cooling fan44. In accordance with this feature, by the shielding member46, it is possible to suppress a change in the air volume, the air direction, etc., of the cooling air due to the circling wind generated by rotation of the cutter blade20. Accordingly, it is possible to stably cool the control unit42and the motor40. Further, it is possible to suppress foreign matter such as lawn grass or the like from flowing into the cooling fan44together with the circling wind.

In the electric unit10A, the guide walls118,119are provided which guide the cooling air toward the discharge port82. In accordance with this feature, the cooling air inside the casing38can be discharged smoothly from the discharge port82.

As shown inFIGS.7and8, an electric unit10B may be incorporated in a cover member140of a walking type cultivating machine12B that serves as an operating machine, for example. In this case, the electric unit10B is equipped with the electric unit main body34, the battery36, and a mounting member142. The electric unit main body34is arranged in a manner so that the shaft88extends in a horizontal direction. Non-illustrated tilling claws are provided on a side of the shaft88opposite to a side where the rotor86is positioned. The battery36is arranged above the electric unit main body34with a gap S3therebetween. An air introducing unit143of the cover member140is directed toward the gap S3formed between the electric unit main body34(casing38) and the battery36. More specifically, the battery36is disposed on a more upstream side than the control unit42in the cooling flow path of the cooling air.

The mounting member142serves to fix the electric unit main body34to the cover member140. The mounting member142is arranged between the electric unit main body34and the cover member140. The mounting member142includes a plate-shaped mount main body144, which is attached to the electric unit main body34, and a plurality of bushes146arranged between the mount main body144and the cover member140. In addition, by fastening a plurality of bolts148, which are inserted through holes140aof the cover member140and holes144aof the mount main body144, to the electric unit main body34, the electric unit main body34is securely fixed to the cover member140.

As shown inFIG.9, in this type of electric unit10B, when the control unit42drives the motor40and the cooling fan44is rotated, outside air (air), which is introduced from the air introducing unit143of the cover member140, flows as cooling air into the gap S3between the battery36and the casing38of the electric unit main body34. Consequently, the battery36is cooled by the cooling air. In addition, the cooling air that has cooled the battery36is guided via the filter member66and the intake port51into the gap S2formed between the control unit42and the rotor86. Consequently, the control unit42and the stator84are uniformly cooled by the cooling air.

Thereafter, the cooling air is guided into the first space52a, and cools the motor40by passing through the gap S1formed between the rotor86and the casing38and also passing through the inner side (stator84) of the rotor cup96. The cooling air that has cooled the motor40is guided into the second space52b, flows outward in a radial direction of the cooling fan44, and is discharged to the exterior of the casing38via the discharge port82. The cooling air that is discharged to the exterior of the casing38is led outside of the cover member140from an air lead-out unit150of the cover member140.

In this case, the battery36is disposed on a more upstream side than the control unit42in the cooling flow path. Therefore, even in the case that the temperature of the battery36becomes comparatively high, the battery36, the control unit42, and the motor40can be effectively cooled.

The electric unit according to the present invention is not limited to the example of being incorporated in the lawn mower12A and the cultivating machine12B, as were described above, and for example, can be incorporated in an arbitrary direction in various operating machines, such as a high pressure washer, a transporting machine, a dozer, a rolling compactor, a portable aspirator (rescue pump), a rammer or the like.

The electric unit according to the present invention is not limited to the above-described embodiments, and it is a matter of course that various additional or alternative configurations could be adopted therein without departing from the essence and gist of the present invention as set forth in the appended claims.

DESCRIPTION OF REFERENCE NUMERALS