Patent Publication Number: US-2023137009-A1

Title: Water jacket and method of manufacturing water jacket

Description:
This application is based on and claims the benefit of priority from Chinese Patent Application No. 202111294231.2, filed on 3 Nov. 2021, the content of which is incorporated herein by reference. 
     BACKGROUND OF THE INVENTION 
     Field of the Invention 
     The present invention relates to a water jacket and a method of manufacturing such a water jacket. 
     Related Art 
     A water jacket of the known art is provided on a peripheral surface of a stator housing of an electric motor (for example, see Japanese Unexamined Patent Application, Publication No. 2002-119019). This water jacket is provided with a turbulence generating member at a coolant Inlet of a coolant jacket. The turbulence generating member generates a turbulent flow in the coolant flowing toward the coolant jacket, and causes the coolant to flow substantially uniformly into the coolant jacket, thereby improving the cooling efficiency. 
     Patent Document 1: Japanese Unexamined Patent Application, Publication No. 2002-119019 
     SUMMARY OF THE INVENTION 
     The coolant jacket of the above-described water jacket of the known art has a large width and extends in the circumferential direction of the stator housing, which is a heat generating portion, such that the coolant jacket surrounds the stator housing. Therefore, even though the turbulence generating member generates a turbulent flow in the coolant flowing into the coolant jacket, the effect of the turbulent flow attenuates while the coolant is flowing in the flow path of the coolant jacket that is curved in the circumferential direction of the stator housing. Thus, the water jacket of the known art has room for improvement from the viewpoint of causing the entire coolant jacket to efficiently perform cooling. 
     It is an object of the present invention to provide a water jacket capable of cooling a heat generating portion with improved efficiency, and a method of manufacturing such a water jacket. 
     A first aspect of the present invention is directed to a water jacket (e.g., a water jacket  1  to be described later) including a housing (e.g., a housing  2  to be described later) configured to be disposed on or adjacent to an outer periphery of a heat generating portion (e.g., a stator core  101  to be described later) and a coolant channel (e.g., a coolant channel  3  to be described later) provided inside the housing. The coolant channel includes a plurality of main tubular channel portions (e.g., main tubular channel portions  31  to be described later) that extend linearly and are configured to be arranged along and in proximity to the outer periphery of the heat generating portion, an inflow-side manifold portion (e.g., an inflow-side manifold portion  32  to be described later) that collectively connects upstream end portions (e.g., upstream end portions  31   a  to be described later) of the main tubular channel portions and is configured to allow inflow of coolant, and an outflow-side manifold portion (e.g., an outflow-side manifold portion  33  to be described later) that collectively connects downstream end portions (e.g., downstream end portions  31   b  to be described later) of the main tubular channel portions and is configured to allow outflow of the coolant. Each of the main tubular channel portions includes therein a vortex generation part (e.g., a vortex generation part  4  to be described later) that is disposed in proximity to the upstream end portion and configured to generate a vortex flow. 
     A second aspect of the present invention is an embodiment of the first aspect. In the second aspect, the vortex generation part may include a plurality of deflection plates (e.g., deflection plates  41  to be described later) that deflect a flow of the coolant, in the main tubular, channel portion in an identical direction along a circumferential direction (e.g., a direction D 4  to be described later) of the main tubular channel portion. 
     A third aspect of the present invention is an embodiment of the second aspect. In the third aspect, the plurality of deflection plates may be integrated with an inner wall surface (e.g., an inner wall surface  31   c  to be described later) of the main tubular channel portion. 
     A fourth aspect of the present invention is directed to a method of manufacturing the water jacket according to any one of the first to third aspects as a one-piece article. The method includes performing additive manufacturing using a metal material. 
     According to the first aspect, the vortex generation parts can generate a vortex flow in the main tubular channel portions, which form part of the coolant channel and extend linearly, whereby the coolant channel increases in heat; transferability and can cool the heat generating portion with further improved efficiency. 
     According to the second aspect, a vortex flow can be easily generated in each main tubular channel portion by the plurality of deflection plates provided in the main tubular channel portion. 
     According to the third aspect, the plurality of deflection plates extending from the inner wall surface of each main tubular channel portion can more efficiently generate a vortex flow in the main tubular channel portion. 
     According to the fourth aspect, the water jacket capable of cooling the heat generating portion with further improved efficiency can be easily manufactured using a 3D printer. In addition, a vortex flow generated by the vortex generation part in each main tubular channel portion enhances performance for removing the metal material remaining in the coolant channel after completion of the forming process. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG.  1    is a longitudinal sectional view illustrating an electric motor provided with a water jacket according to an embodiment of the present invention; 
         FIG.  2    is a perspective view illustrating only a coolant channel provided inside the water jacket according to the embodiment; 
         FIG.  3    is a partially-cutaway perspective view illustrating a vortex generation part in a main tubular channel portion at the portion denoted with A in  FIG.  1   ; and 
         FIG.  4    is a perspective view illustrating only the vortex generation part according to the embodiment. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Embodiments of the present invention will be described in detail with reference to the accompanying drawings.  FIG.  1    illustrates an electric motor  100  provided with a water jacket  1  according to the present embodiment. The arrows in  FIG.  1    respectively indicate, for the electric motor  100 , an axial direction denoted by D 1  and a radial direction denoted by D 2 . 
     The electric motor  100  includes a stator core  101  having a substantially cylindrical shape and extending in the axial direction, and a rotor  102  rotatably supported in a shaft hole  101   a  of the stator core  101 . The stator core  101  is made of an iron-based metal material, and has a plurality of slots  101   b  accommodating coils  103 . 
     Viihen the electric motor  100  is driven, heat of the coils  103  is transmitted to the stator core  101 , and the stator core  101  generates heat. The water jacket  1  cools the coils  103  through the stator core  101 . In the present embodiment, the stator core  101  is a heat generating portion to be cooled by the water jacket  1 . 
     The water jacket  1  is disposed radially outward of the stator core  101  of the electric motor  100 . The water jacket  1  includes a housing  2  that is configured to be disposed on or adjacent to the outer periphery of the stator core  301 , and a coolant channel  3  that has a tubular shape, is provided inside the housing  2 , and allows coolant for cooling the stator core  101  to flow therethrough, 
     The housing  2  is made of a metal material having good thermal conductivity, such as an alurainura-based material or a copper-based material, and has a shape that surrounds the entire outer periphery of the stator core  101 . The housing  2  is thermally connected to an outer peripheral surface  101   c  of the stator core  101 . The housing  2  of the present embodiment is in direct contact with the outer peripheral surface  101   c  of the stator core  101 . However, the housing  2  may be thermally connected to the outer peripheral surface  101   c  of the stator core  101  via a heat transferable material such as a heat conductive medium containing fine metal particles. 
     As illustrated in  FIG.  2   , the coolant channel  3  through which the coolant flows is formed inside the housing  2 . The coolant channel  3  includes a plurality of main tubular channel portions  31 , at least one inflow-side manifold portion  32 , and at least one outflow-side manifold portion  33 . 
     The main tubular channel portions  31  are disposed in proximity to the outer peripheral surface  101   c  of the stator core  101 . The main tubular channel portions  31  of the present embodiment extend linearly .in the axial direction of the stator core  101 . However, the main tubular channel portions  31  may be provided so as to extend in the circumferential direction of the stator core  101 . In the housing  2 , the plurality of main tubular channel portions  31  are arranged in parallel at regular Intervals in a direction  03  that is along the outer periphery of the stator core  101  such that the main tubular channel portions  31  surround the stator core  101 . The main tubular channel portions  31  of the present embodiment are each configured to allow the coolant to flow in the top-to-bottom direction in  FIGS.  1  and  2   . 
     The inflow-side manifold portion  32  has an annular shape adapted to be disposed along the outer periphery of the stator core  101 . The inflow-side manifold portion  32  collectively connects upstream end portions  31   a  of all the main tubular channel portions  31  such that the inflow-side manifold portion  32  communicates with the inside of each of the main tubular channel portions  31 . As illustrated in  FIG.  2   , at least, one inflow pipe  321  that allows the coolant to flow into the coolant channel  3  is connected to the inflow-side manifold portion  32 . 
     The outflow-side manifold portion  33  has an annular shape adapted to be disposed along the outer periphery of the stator core  101 , similarly to the inflow-side manifold portion  32 . The outflow-side manifold portion  33  collectively connects downstream end portions  31   b  of all the main tubular channel portions  31  such that the outflow-side manifold portion  33  communicates with the inside of each of the main tubular channel portions  31 . As illustrated in  FIG.  2   , at least one outflow pipe  331  that allows the coolant to flow into the coolant channel  3  is connected to the outflow-side manifold portion  33 . 
     Each of the main tubular channel portions  31  includes therein a vortex generation part  4  that causes the coolant passing through the main tubular channel portion  31  to form a vortex flow. As illustrated in  FIGS.  1  and  2   , the vortex generation part  4  is disposed in proximity to the upstream end portion  31   a  of the main tubular channel portion  31 . Providing the vortex generation parts  4  allows vortex flows to be easily generated in the main tubular channel portions  31 , thereby improving the heat transferability of the coolant channel  3 . As a result, a temperature gradient in the main tubular channel portions  31  significantly decreases in steepness, and the cooling efficiency for the stator core  101  as a heat generating portion is further improved. 
     As illustrated in  FIGS.  3  and  4   , the vortex generation part  4  of the present embodiment includes a plurality of deflection plates  41  arranged along the circumferential direction (a direction D 4  in  FIGS.  3  and  4   ) of the main tubular channel portion  31 . The plurality of deflection plates  41  of the present embodiment extend in radial directions from the radial center of the main tubular channel portion  31  toward an inner wall surface  31   c  of the main tubular channel portion  31 . However, the plurality of deflection plates  41  may be provided so as to extend from the inner wall surface  31   c  of the main tubular channel, portion  31  toward the radial center of the main tubular channel portion  31 . The vortex generation part  4  of the present embodiment includes five deflection plates  41 , but the number of deflection plates  41  is not limited to five. 
     The deflection plates  41  each have a downstream end  41   a  in terms of a flow direction of the coolant. The downstream ends  41   a  are curved in an identical direction along the circumferential direction of the main tubular channel portion  31 . Consequently, as indicated by arrows in the main tubular channel portion  31  illustrated in  FIG.  3   , the plurality of deflection plates  41  deflect the flow of the coolant in the main tubular channel portion  31  in the identical direction along the circumferential direction of the main tubular channel portion  31 . Therefore, after flowing from the inflow-side manifold portion  32  into each main tubular channel portion  31 , the coolant collides with the plurality of deflection plates  41  of the vortex generation part  4  and thereby passes through the main tubular channel portion  31  in the form of a vortex flow. Since the vortex generation part  4  is disposed in proximity to the upstream end portion  31   a  of the main tubular channel portion  31 , the coolant that has entered the main tubular channel portion  31  can be maintained in the form of a vortex flow over the entire length of the main tubular channel portion  31  extending linearly toward the outflow-side manifold portion  33 . 
     As illustrated in  FIG.  3   , the plurality of deflection plates  41  of the vortex generation part  4  of the present embodiment are integrated with the inner wall surface  31   c  of the main tubular channel portion  31 . Specifically, the deflection plates  41  illustrated in  FIG.  4    each have its outer end  41   b  connected to the inner wall surface  31   c . This configuration makes it possible to deflect the coolant flowing along the inner wall surface  31   c  of the main tubular channel portion  31  by causing the coolant to collide with the deflection plates  41 , whereby the entire coolant flowing through the main tubular channel portion  31  is efficiently brought into the form of a vortex flow. Thus, the vortex generation part  4  of the present embodiment can further efficiently generate a vortex flow in the main tubular channel portion  31 . 
     The water jacket  1  with the above-described configuration can be manufactured by way of an additive manufacturing method, according to which the housing  2  and the coolant channel  3  having the vortex generation parts  4  inside the main tubular channel portions  31  are formed by layering the same metal material (e.g., powder metal or metal wire). According to this manufacturing method, the housing  2  and the coolant channel  3  having the vortex generation parts A inside the main tubular channel portions  31  can be easily formed as a one-piece article, using a 3D printer. Examples of the metal material include aluminum-based materials and copper-based materials having good thermal conductivity. 
     The additive manufacturing method employing a 3D printer and using powder metal as the metal material can be carried out in the following manner, for example. The powder metal is spread over a base plate. A step of melting a portion of the powder metal to be formed, by irradiation of a laser or an electron beam as a heat source, a step of solidifying the metal powder, and a step of moving the base plate to spread new powder metal over the base plate are repeated, whereby the water jacket  1  is three-dimensionally formed in a layered manner along the direction Dl, which is the length direction of the main tubular channel portions  31 . According to this additive manufacturing method, the water jacket  1  capable of cooling the stator core  101  with further improved efficiency can be easily manufactured using a 3D printer. In addition, a vortex flow generated in each main tubular channel portion  31  by the vortex generation part A enhances performance for removing the metal material remaining in the coolant channel  3  after the completion of the forming process. 
     In summary, the water jacket i according to the present embodiment provides the following advantages. The water jacket  1  according to the present embodiment includes the housing  2  configured to be disposed on or adjacent to the outer periphery of the stator core  101  as a heat, generating portion and the coolant channel  3  provided inside the housing  2 . The coolant channel  3  includes the plurality of main tubular channel portions  31  that extend linearly and are configured to be arranged along and in proximity to the outer periphery of the stator core  101 , the inflow-side manifold portion  32  that collectively connects the upstream end portions  31   a  of the main tubular channel portions  31  and is configured to allow inflow of the coolant, and the outflow-side manifold portion  33  that collectively connects the downstream end portions  31   b  of the main tubular channel portions  31  and is configured to allow outflow of the coolant. Each of the main tubular channel portions  31  includes therein the vortex generation part  4  that is disposed in proximity to the upstream end portion  3 ia and configured to generate a vortex flow. According to this configuration, the vortex generation parts  4  can generate a yortex flow in the main tubular channel portions  31 , which form part of the coolant channel  3  and extend linearly, whereby the coolant channel  3  increases in heat transferability and can cool the stator core  101  with further improved efficiency. 
     The vortex generation part  4  of the present embodiment includes the plurality of deflection plates  41  that deflect a flow of the coolant in the main tubular channel portion  31  in an identical direction along the circumferential direction of the main tubular channel portion  31 . According to this configuration, a vortex flow can be easily generated in each main tubular channel portion  31  by the plurality of deflection plates  41  provided in the main tubular channel portion  31 . 
     The plurality of deflection plates  41  of the present embodiment are integrated with the inner wall surface  31   c  of the main tubular channel portion  31 . According to this configuration, the plurality of deflection plates  41  extending from the inner wall surface  31   c  of each main tubular channel portion  31  can more efficiently generate a vortex flow in the main tubular channel portion  31 . 
     According to the present embodiment, a method of manufacturing the water jacket  1  as a one-piece article includes performing additive manufacturing using a metal material. According to this method, the water jacket  1  capable of cooling the stator core  101  with further improved efficiency can be easily manufactured using a 3D printer. In addition, a vortex flow generated by the vortex generation part  4  in each main tubular channel portion  31  enhances performance for removing the metal material remaining in the coolant channel  3  after completion of the forming process. 
     Although the water jacket  1  described in the above embodiment is configured to be provided to the electric motor  100  having the stator core  101  as a heat generating portion, the heating portion is not limited to the electric motor  100 . The water jacket  1  can be provided on or adjacent to various heat generating portions that are required to be cooled by a coolant. 
     EXPLANATION OF REFERENCE NUMERALS 
       1 : Water jacket 
       2 : Housing 
       3 : Coolant channel 
       31 : Main tubular channel portion 
       31   a : Upstream end portion 
       31   b : Downstream end portion 
       31   c : Inner wall surface 
       32 : Inflow-side manifold portion 
       33 : Outflow-side manifold portion 
       4 : Vortex generation part 
       41 : Deflection plate 
       101 : Stator core (heat generating portion)