Cooling system of an electric motor with fan

Abstract

Cooling system of an electric motor (1) with fan (2), comprising: a fan (2) configured to generate a fluid flow (3) for cooling the electric motor (1); a guide channel (4) which forms a flow channel (5, 6) for guiding the fluid flow (3) generated by the fan (2); at least one hole (8) provided in a straight section of the guide channel (4); and at least one more hole (7), where: that at least one hole (8) is provided on one side with respect to the direction of flow of the fluid flow (3) through the straight section of the guide channel (4), that at least one hole (8) is located in the direction of flow of the fluid stream (3) downstream of the fan (2), wherein the at least one hole (8) provides an outlet for a partial flow to flow out of the guide channel (4) and thus to cool the electric motor (1), that at least one hole (8) is located upstream of a predetermined position in the direction of flow of the fluid stream (3), where a retention occurs in the guide channel (4) to reduce the resistance to the fluid stream (3), the guide channel (4) comprises: a first flow channel (5) which is connected to the fan (2), and a second flow channel (6) which is connected to the first flow channel (5) and thus receives the fluid flow (3) from the first flow channel (5), that at least one hole (8) is provided in the first flow channel (5) which defines the straight section, that at least one further hole (7) is provided in the second flow channel (6), which is another straight section of the guide channel, that at least one further hole (7) is provided on one side with respect to the direction of flow of the fluid flow (3) through the further straight section of the guide channel (4), the first flow channel (5) extends along a first side of the electric motor (1), and the second flow channel (6) is angled with respect to the first flow channel (5) and extends along another second side of the electric motor (1).

Description

Background of the invention 1. Field of the invention

[0001] The present invention relates to a cooling system of an electric motor with a fan. 2. Description of related technology

[0002] An electric motor generally includes a cooling system to improve efficiency. As a cooling system, a configuration in which a fan is attached to a rotor including an electric motor, and a rotary motor is cooled by an airflow generated by the fan rotating with the rotation of the rotor; a configuration in which a flow channel for the cooling coolant is provided in a component including an electric motor, and the electric motor is cooled by the flow of the cooling coolant in the channel; and a configuration in which an external fan is attached to an electric motor, and the electric motor is cooled by an airflow generated by the external fan.

[0003] As a prior art of the cooling system for cooling an electric motor, JP 2011-36006 A discloses a configuration in which a fan is attached to a rotor so that an electric motor rotates while generating a fluid flow for cooling the electric motor. JP 2011-55654 A proposes a configuration in which a flow channel is provided between a winding head and a winding head cover, and a fluid flowing through the channel performs cooling. Furthermore, JP H02-188143 A discloses an electric motor in which an external fan cools the electric motor, while also providing an internal fan in the electric motor to prevent a decrease in cooling efficiency.

[0004] However, previous techniques have the problems outlined below.

[0005] In fan-assisted cooling, a guide channel, including a flow channel, is provided to guide the fluid flow generated by the fan. In some cases, depending on the configuration of the guide channel, the resistance to the fluid is high, and in this case, the fluid pressure and flow rate are not fully utilized, and the expected cooling capacity is not achieved.

[0006] However, if the expected cooling capacity is not achieved, the duct configuration is changed, the fan capacity is increased, or a fan is added to increase the cooling capacity, thus solving the problem. However, in some cases, changing the duct configuration is limited by the machine configuration, and in this case, there is a problem that improving the fan capacity and adding a fan will result in increased costs.

[0007] The document DE 475 433 A discloses a cooling device for completely encapsulated electrical machines with an annular distribution chamber which is provided on one side of the machine housing, is directly connected thereto and is continuously supplied with a coolant from an external source.

[0008] The document DE 971 497 B discloses a commutator machine with forced ventilation without radial cooling slots in the stator and rotor, wherein annular housing spaces are provided at several points of the machine distributed in the axial direction, to which the cooling air is supplied from a collecting duct on the back of the machine according to their axial sequence, and from the annular housing spaces the cooling air is supplied to the parts of the machine to be cooled via separate cooling paths.

[0009] The document FR 2 367 371 A1 discloses an electric motor which is fastened by its output-side end to the wall of a work machine and is provided with a fan blade on its opposite end, wherein cooling air ducts are provided around the motor, which are provided with outlet openings which are directed towards the wall of the work machine and are arranged at some distance from it, wherein the cooling air ducts provided with outlet openings directed towards the wall are provided only on a part of the circumference of the motor and further cooling air ducts are provided which run outwards on the remaining part of the circumference of the motor up to the wall and are closed off in the axial direction and have outlet openings on the end of the motor facing the wall, outside the motor housing, which are directed radially towards the shaft of the rotor. Summary of the invention

[0010] In view of the above-described problems in the prior art, it is the purpose of the present invention to provide a cooling system having a fan in which the cooling capacity of the cooling system can be increased without changing the configuration of the guide channel for guiding the fluid flow generated by the fan and without improving the fan capacity and adding the fan.

[0011] According to the invention, a cooling system for an electric motor with a fan is provided according to the independent claim. Developments are provided in the dependent claims.

[0012] A cooling system of an electric motor with a fan according to the invention preferably includes a fan configured to generate a fluid flow for cooling the electric motor, and a guide channel forming a flow channel for guiding a fluid flow generated by the fan, wherein at least one hole is provided in the guide channel.

[0013] The guide channel may consist of a first flow channel connected to the fan and a second flow channel connected to the first flow channel, wherein at least one hole is provided in the first guide channel.

[0014] The rotation axis of the fan may not be parallel to the rotation axis of the electric motor.

[0015] The rotation axis of the fan may be parallel to the rotation axis of the electric motor.

[0016] The present invention, with the above configuration, enables an improvement in cooling capacity without changing the configuration of the guide channel for guiding the fluid flow generated by the fan, without improving the capacity of the fan, and without adding the fan in a fan-type cooling system. With this configuration, a cooling system can be implemented at low cost. Short description of the drawings

[0017] The above-described object, other objects, and features of the invention will be more fully understood from the following description of embodiments with reference to the accompanying drawings. In these drawings: Fig. 1 is a view of a cooling system with an external fan in a prior art. Fig. 2 is a view of a cooling system with an external fan in a prior art in a direction of an arrow A. Fig. 3 is a view of a cooling system with an external fan according to Embodiment 1 of the present invention. Fig. 4 is a view of a cooling system with an external fan according to Embodiment 1 of the present invention in a direction of an arrow B. Fig. 5 is a view of a cooling system with an external fan according to Embodiment 2 of the present invention. Detailed description of the preferred embodiments

[0018] Embodiments of the present invention will be described with reference to the drawings. Components identical or similar to components in a conventional induction motor are designated by identical reference numerals.

[0019] Fig. 1 is a view of a cooling system of an electric motor with an external fan in an example of a prior art. The electric motor 1 includes an external fan 2 as a cooling system and a guide channel 4 for guiding the fluid flow 3 generated by the rotation of the external fan 2. The guide channel 4 consists of a first flow channel 5 connected to the external fan 2 and a second flow channel 6 connected to the first flow channel.

[0020] Here, it is assumed that the external fan 2 is not a type capable of speed control, but a type that rotates at a constant speed when a constant electrical voltage is input. The fluid flow 3 generated by the rotation of the external fan 2 is guided through the guide channel and flows around an electric motor 1. The fluid flow 3 dissipates heat generated by the electric motor 1 and conducts the heat from the guide channel 4 to the outside. At this time, the resistance to the fluid flow 3 is large because the electric motor 1 is placed in front of the external fan. In addition, a flow channel consisting of the guide channel 4 has a narrow cross-section, so the resistance to the fluid flow 3 is large.

[0021] Therefore, even though the external fan 2 rotates at a single speed, a counterflow is generated, reducing the overall flow rate to less than the original flow rate that the external fan can generate. As a result, the original flow rate that the external fan 2 can generate is not fully generated, and the electric motor 1 to be cooled cannot be sufficiently cooled.

[0022] In addition, a portion of the fluid flow 3 generated by the external fan 2 sometimes remains in the flow channel. The remaining flow prevents the cooling of the electric motor 1.

[0023] Fig. 2 is a view in a direction of an arrow A of Fig. 1. The fluid flow 3 is guided through the flow channel 4 so that it flows to a surface opposite a surface to which the external fan 2 is attached.

[0024] Fig. Figure 3 is a view of a cooling system with an external fan according to an embodiment of the present invention. Components connected to components in Fig. 1 are identical or similar to these, are designated by identical reference numerals. The difference between the guide channel configuration of the present embodiment and the guide channel configuration of the cooling system with the external fan in the prior art is that the holes 7, 8 for discharging the fluid flow 3 are provided on the guide channel 4.

[0025] By providing the holes 7, 8 on the guide channel 4, the resistance to the fluid flow through the guide channel 4 is reduced. The portion of the fluid flow 3 generated by the rotation of the external fan 2, which flows backward and thus reduces the total flow rate in the prior art, flows out through the holes 7, 8 to cool the electric motor 1. With this configuration, the entire original flow rate that the external fan can generate can be used to cool an object to be cooled, and the cooling of the electric motor 1 to be cooled is sufficiently achieved.

[0026] Regarding the position where the hole is provided, the hole is provided at the first flow channel 5 connected to the external fan 2, thereby producing an effect. In the embodiment, the hole 8 corresponds to the hole provided at the first flow channel 5 connected to the external fan 2.

[0027] In addition, the position at which a restriction to the flow is likely to be generated in the guide channel 4 can be confirmed by an experiment, a simulation or the like, and the holes 7, 8 can be provided in the vicinity of the position, preferably the position before the confirmed position, in order to more effectively reduce the resistance to the fluid flow 3.

[0028] Fig. 4 is a view in a direction of an arrow B of Fig. 3. The fluid flow 3 is guided through the guide channel so that it flows to a surface opposite to a surface to which the external fan 2 is attached, while the fluid flow 3 flows outward from the guide channel 4 through a plurality of holes 7, 8 provided on the guide channel 4.

[0029] Fig. 5 is a view of a duct configuration of a cooling system with an external fan according to another embodiment of the present invention. Components connected to components in Fig. 3 are identical or similar to these, are designated by identical reference numerals. The external fan 2 is mounted such that a rotational axis of the external fan 2 is not parallel to a rotational axis of the electric motor 1 in Fig. 3 is, while Fig. 5 shows an example in which the external fan 2 is mounted such that a rotation axis of the external fan 2 is parallel to a rotation axis of the electric motor 1.

[0030] In this case, by providing the holes 7, 8 on the guide channel 4, the resistance to the fluid flow through the guide channel 4 is reduced, and the part of the fluid flow 3 generated by the rotation of the external fan 2 and flowing backwards, thus reducing the total flow rate in the prior art, flows out of the holes, so that the entirety of the original flow rate that the external fan can generate can be used to cool an object to be cooled.

[0031] In the above configuration, sufficient cooling is performed without changing the configuration of the guide channel for guiding the fluid flow generated by the fan and without improving the capacity of the fan and adding the fan in a fan-type cooling system.

[0032] The embodiments of the present invention are described above. However, the present invention is not limited to the above-described embodiments, and its configuration may be appropriately modified to be implemented in other embodiments.

[0033] For example, in the above-described embodiments of the present invention, it is assumed that the fan is of the type in which the speed cannot be controlled, but the type in which the speed can be controlled may be used. It should be noted that regarding the configuration of the hole provided on the guide channel, as shown in Fig. 3, the configuration of the hole is not limited to a circular one.

Claims

[1] Cooling system of an electric motor (1) with fan (2), comprising: a fan (2) configured to generate a fluid flow (3) for cooling the electric motor (1); a guide channel (4) forming a flow channel (5, 6) for guiding the fluid flow (3) generated by the fan (2); at least one hole (8) provided in a straight section of the guide channel (4); and at least one more hole (7), where: the at least one hole (8) is provided on one side with respect to the flow direction of the fluid flow (3) through the straight section of the guide channel (4), the at least one hole (8) is located downstream of the fan (2) in the flow direction of the fluid flow (3), wherein the at least one hole (8) provides an outlet for a partial flow to flow out of the guide channel (4) and thus to cool the electric motor (1), the at least one hole (8) is located in the flow direction of the fluid flow (3) upstream of a predetermined position at which a retention is created in the guide channel (4) in order to reduce the resistance for the fluid flow (3), the guide channel (4) comprises: a first flow channel (5) connected to the fan (2), and a second flow channel (6) connected to the first flow channel (5) and thus receiving the fluid flow (3) from the first flow channel (5), the at least one hole (8) is provided in the first flow channel (5) which defines the straight section, the at least one further hole (7) is provided in the second flow channel (6), which is a further straight section of the guide channel, the at least one further hole (7) is provided on one side with respect to the flow direction of the fluid flow (3) through the further straight section of the guide channel (4), the first flow channel (5) extends along a first side of the electric motor (1), and the second flow channel (6) is angled with respect to the first flow channel (5) and extends along another second side of the electric motor (1). [2] Cooling system of an electric motor (1) with fan (2) according to claim 1, wherein an axis of rotation of the fan (2) does not run parallel to an axis of rotation of the electric motor (1). [3] Cooling system of an electric motor (1) with fan (2) according to claim 1, wherein an axis of rotation of the fan (2) runs parallel to an axis of rotation of the electric motor (1).

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