Patent Publication Number: US-7905203-B2

Title: Oil cooler for vehicle

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     The present invention claims priority under 35 USC §119 based on Japanese patent application No. 2007-221590 filed 28 Aug. 2007. The subject matter of this priority document is incorporated by reference herein. 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to an oil cooler for a vehicle, in which a heat exchange core is housed in a casing such that a cooling water passage is formed around the heat exchange core, wherein the casing includes a cylindrical sidewall part, the heat exchange core includes an inlet-side oil passage and an outlet-side oil passage which extend parallel to each other along an axis of the sidewall part, the heat exchange core enables oil to be delivered from the inlet-side oil passage to the outlet-side oil passage, and an inlet pipe and an outlet pipe are connected to the sidewall part, the inlet pipe forming a cooling water inlet passage in communication with the cooling water passage, and the outlet pipe forming a cooling water outlet passage in communication with the cooling water passage. 
     2. Description of the Related Art 
     Japanese Patent Application Laid-open No. 2001-215091 has made known the following oil cooler for a vehicle. In the oil cooler, a heat exchange core is housed in a cylindrical casing with first and second plates fastened to its opposite end portions, and the heat exchange core includes an inlet-side oil passage and an outlet-side oil passage which extend parallel to each other along the axis of the casing. An inlet pipe and an outlet pipe are connected to the casing. The inlet pipe forms a cooling water inlet passage, and the outlet pipe forms a cooling water outlet passage. 
     In the conventional oil cooler as disclosed by Japanese Patent Application Laid-open No. 2001-215091, a spacing between the outer periphery of the heat exchange core and the inner periphery of the casing is narrow, and the flow of cooling water in such a narrow spacing increases the flow rate of the cooling water locally. For this reason, it is likely that cavitation may occur near the inlet-side oil passage where the temperature of the flowing oil is higher than any other part, and that erosion may occur. Measures for preventing such troubles include: enlarging the spacing between the outer periphery of the heat exchange core and the inner periphery of the casing; and arranging the inlet-side oil passage such that it is spaced away from the inner surface of the casing. However, if the spacing is increased, the outer peripheral radius of the heat exchange core has to be decreased, and the heat exchange efficiency accordingly deteriorates. On the other hand, if the inner peripheral radius of the casing is increased, the oil cooler has to be constructed in a larger size. Moreover, if the inlet-side oil passage is arranged spaced away from the inner surface of the casing, the distance between the inlet-side oil passage and the outlet-side oil passage is shortened, and the heat exchange efficiency accordingly deteriorates. 
     SUMMARY OF THE INVENTION 
     The present invention has been achieved in view of the above-described circumstances, and it is an object thereof to provide an oil cooler for a vehicle which can be constructed in a relatively small size without decreasing its heat exchange efficiency, as well as concurrently preventing cavitation and erosion from occurring due to the flow of cooling water in an area corresponding to the inlet-side oil passage. 
     In order to achieve the above object, according to a first aspect and feature of the present invention, there is provided an oil cooler for a vehicle, in which a heat exchange core is housed in a casing such that a cooling water passage is formed around the heat exchange core, wherein the casing includes a cylindrical sidewall part, the heat exchange core includes an inlet-side oil passage and an outlet-side oil passage which extend parallel to each other along an axis of the sidewall part, the heat exchange core enables oil to be delivered from the inlet-side oil passage to the outlet-side oil passage, and an inlet pipe and an outlet pipe are connected to the sidewall part, the inlet pipe forming a cooling water inlet passage in communication with the cooling water passage, and the outlet pipe forming a cooling water outlet passage in communication with the cooling water passage, wherein, outward of the inlet-side oil passage, an outwardly swelling part is formed in the sidewall part of the casing. 
     With the first aspect and feature, outward of the inlet-side oil passage, the outwardly swelling part is formed in the sidewall part of the casing. For this reason, in a location corresponding to the inlet-side oil passage, the spacing between the inner surface of the sidewall part and the outer periphery of the heat exchange core can be set larger than in a case where the outwardly swelling part would not be formed. Thus, it is possible to increase the cross-sectional area of passage of the cooling water, and accordingly to decrease the flow rate of the cooling water. This makes it unnecessary to set the spacing between the outer periphery of the heat exchange core and the inner periphery of the casing larger throughout the circumference, and also makes it unnecessary to arrange the inlet-side oil passage spaced away from the inner surface of the casing. This makes it possible to avoid the oil cooler being constructed in a large size, and to avoid decreasing the heat exchange efficiency, as well as to concurrently prevent cavitation and erosion from occurring due to the flow of the cooling water in the location corresponding to the inlet-side oil passage. 
     According to a second aspect and feature of the present invention, in addition to the first aspect and feature, as seen in a plan view projected onto a plane orthogonal to the axis of the sidewall part, the cooling water inlet and outlet passages are distributed to, and arranged on opposite sides of a straight line passing through an axis of the inlet-side oil passage and an axis of the outlet-side oil passage, respectively, and the outwardly swelling part is formed in the sidewall part in a location opposite to the cooling water inlet passage with respect to the inlet-side oil passage. 
     With the second aspect and feature, as seen in the plan view projected onto the plane orthogonal to the axis of the sidewall part of the casing, the cooling water inlet passage and the cooling water outlet passage are distributed to, and arranged on opposite sides of the straight line passing the axis of the inlet-side oil passage and the axis of the outlet-side oil passage. This arrangement makes it possible to cause the cooling water introduced to the inside of the casing to flow in the casing effectively. Moreover, the outwardly swelling part is formed in the sidewall part of the casing in the location opposite to the cooling water inlet passage with respect to the inlet oil passage. This makes it possible to effectively prevent cavitation from occurring by arranging the outwardly swelling part in an area corresponding to the inlet-side oil passage where the flow of the cooling water coming in from the cooling water inlet passage hits the inner surface of the sidewall part. 
     According to a third aspect and feature of the present invention, in addition to the first aspect and feature, as seen in a plan view projected onto a plane orthogonal to the axis of the sidewall part, the outwardly swelling part is formed in the sidewall part over an area extending between two points at which a second straight line intersects the sidewall part, the second straight line passing through an axis of the inlet-side oil passage in a manner orthogonal to a first straight line passing through the axis of the sidewall part and the axis of the inlet-side oil passage. 
     With the third aspect and feature, as seen in the plan view projected onto the plane orthogonal to the axis of the sidewall part of the casing, the outwardly swelling part is formed in the sidewall part over an area extending between two points at which the second straight line intersects the sidewall part. In this respect, the second straight line is that which passes through the axis of the inlet-side oil passage, and which is orthogonal to the first straight line passing through the axis of the sidewall part and the axis of the inlet-side oil passage. This makes it possible to form the outwardly swelling part in the sidewall part over an area in which the cavitation may occur, and thus to avoid forming the outwardly swelling part larger than necessary, as well as accordingly to avoid the casing being constructed in a large size. 
     According to a fourth aspect and feature of the present invention, in addition to any of the first to third aspects/features, the inlet pipe and the outlet pipe are connected to the sidewall part in such a way as to be spaced away from each other in a direction along the axis of the sidewall part, and the outwardly swelling part is arranged so as to extend, in a direction along the axis of the sidewall part, between a portion where the inlet pipe is connected to the sidewall part and a portion where the outlet pipe is connected to the sidewall part. 
     With the fourth aspect and feature, in the invention according to any one of first to third aspects/features, the inlet pipe forming the cooling water inlet passage and the outlet pipe forming the cooling water outlet passage are arranged spaced away from each other in the axial direction of the sidewall part. In addition, the outwardly swelling part is arranged so as to extend, in a direction along the axis of the sidewall part, between the portion where the inlet pipe is connected to the sidewall part and the portion where the outlet pipe is connected to sidewall part. These arrangements make it possible to arrange the outwardly swelling part in an area where the amount of cooling water flow is larger, and accordingly to avoid the outwardly swelling part being formed larger than necessary. This makes it possible to avoid the casing being constructed in a large size. 
     According to a fifth aspect and feature of the present invention, in addition to any of the first to fourth aspects/features, longitudinal opposite end portions of the outwardly swelling part lengthened in a direction along the axis of the sidewall part have arcuate curve surfaces. 
     With the fifth aspect and feature, the outwardly swelling part is lengthened in the axial direction of the sidewall part, and the longitudinal opposite end portions of the outwardly swelling part have arcuate curve surfaces. This makes it possible to prevent the cooling water flow from fluctuating around the boundary between the outwardly swelling part and the sidewall part in each of the longitudinal opposite end portions of the outwardly swelling part. 
     Descriptions will be provided hereinbelow for illustrative embodiments of the present invention on the basis of the examples of the present invention which are shown in the attached drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIGS. 1 to 5  show a first illustrative embodiment of the present invention. 
         FIG. 1  is a longitudinal sectional view of an oil cooler taken along a line  1 - 1  of  FIG. 2 . 
         FIG. 2  is a cross-sectional view of the oil cooler taken along a line  2 - 2  of FIG.  1 . 
         FIG. 3  is a side view of the oil cooler shown in  FIG. 2 , viewed in a direction indicated by an arrow  3 . 
         FIG. 4  is a cross-sectional view of the oil cooler taken along a line  4 - 4  of  FIG. 1  with a heat exchange core being illustrated in a simplified manner. 
         FIG. 5  is a side view of the oil cooler shown in  FIG. 2 , viewed in a direction indicated by an arrow  5 . 
         FIG. 6  is a cross-sectional view of an oil cooler according to a second illustrative embodiment of the present invention. 
         FIG. 7  is a cross-sectional view of an oil cooler according to a third illustrative embodiment of the present invention. 
         FIG. 8  is an enlarged detail view of a portion of  FIG. 4 , showing details of the structure in the area of the outwardly swelling part of the cylindrical sidewall. 
     
    
    
     DESCRIPTION OF THE PRESENT EMBODIMENTS 
     Referring to  FIGS. 1 to 5 , an oil cooler shown therein is used for an engine of a motorcycle for example. The oil cooler includes: a casing  12 A attached to an engine case  11 ; and a heat exchange core  13  housed in the casing  12 A. 
     The casing  12 A is of a bottomed cylindrical shape formed by closing one end of a cylindrical sidewall part  12 Aa with an end wall part  12 Ab, which integrally communicates with the sidewall part  12 Aa. As seen in  FIG. 8 , the cylindrical sidewall part  12 Aa includes a first outer case wall portion  40  disposed at a first radial distance from a central axis C 3  (see also  FIG. 2 ). The first outer case wall portion  40  is spaced a first distance away from an outer edge portion  42  of the heat exchange core  13 , so as to form a first channel portion  44  therebetween having a first depth. Referring now to  FIG. 1 , it will be seen that an oil chamber plate  14  is fitted into the other end portion of the sidewall part  12 Aa, opposite the end wall part  12 Ab. In addition, an attachment plate  15  is provided adjacent to, and fixed to the other end of the sidewall part  12 Aa. The attachment plate  15  abuts the oil chamber plate  14 . This attachment plate  15  is fastened to the engine case  11  with multiple fasteners, for example, with four bolts  16 . An annular sealing member  17  is placed between the engine case  11  and the attachment plate  15 . 
     The heat exchange core  13  is formed by laying a plurality of layers of first and second core plates  18  and  19  one on another in an axial direction of sidewall part  12 Aa of the casing  12 A, in which the first core plate  18  and the second core plate  19  in each layer are connected together by press-molding so as to have predetermined concave and convex shapes. This heat exchange core  13  is held between the end wall part  12 Ab and the oil chamber plate  14 . The outer edge portion  42  of the heat exchange core  13  has a substantially circular outline shape in plan view, as shown in  FIG. 4 . Moreover, the heat exchange core  13  includes: an inlet-side oil passage  20  and an outlet-side oil passage  21  which both extend in parallel to each other and substantially parallel to a central axis C 3  of the casing  12 A. The heat exchange core  13  also has multiple exchange passages  22  formed therein, as shown, for exchanging oil from the inlet-side oil passage  20  to the outlet-side oil passage  21 . This heat exchange core  13  is housed in the casing  12 A. Additionally, as shown in  FIG. 4 , the axis C 1  of the inlet-side oil passage  20  and the axis C 2  of the outlet-side oil passage  21  are arranged on a straight line L 1  passing through the central axis C 3  of the sidewall part  12 Aa as seen in a plan view projected onto a plane orthogonal to the axis of the sidewall part  12 Aa. 
     In the casing  12 Aa, a cooling water passage  23  is formed around the heat exchange core  13 . The heat exchange core  13  is provided with multiple inner fins  24  each facing the inlet-side oil passage  20 , the exchange passage  22 , and the outlet-side oil passage  21 . The heat exchange core  13  is provided with multiple inner fins  25 , each facing the cooling water passage  23 . 
     In addition, the oil chamber plate  14  comprises: an inlet hole  28  communicating with the inlet-side oil passage  20 ; and an outlet hole  29  communicating with the outlet-side oil passage  21 . The attachment plate  15  comprises: an inlet-side communication hole  31  through which a first oil passage  30  provided to the engine case  11  communicates with the inlet hole  28 ; and an outlet-side communication hole  33  through which a second oil passage  32  provided to the engine case  11  communicates with the outlet hole  29 . 
     Referring also to  FIG. 4 , an inlet pipe  35  and an outlet pipe  37  are connected to the sidewall part  12 Aa of the casing  12 A. The inlet pipe  35  forms a cooling water inlet passage  34  communicating with the cooling water passage  23 . The outlet pipe  37  forms a cooling water outlet passage  36  communicating with the cooling water passage  23 . As seen in a plan view projected onto a plane orthogonal to the axis of the sidewall part  12 Aa, the cooling water inlet passage  34  and the cooling water outlet passage  36  are distributed to, and arranged on opposite sides of the line L 1  passing through the axis C 1  of the inlet-side oil passage  20  and the axis C 2  of the outlet-side oil passage  21 . In addition, as clearly shown in  FIG. 3 , the inlet pipe  35  and the outlet pipe  37  are connected to the sidewall part  12 Aa in a way that the inlet pipe  35  and the outlet pipe  37  are spaced away from each other in the axial direction of the sidewall part  12 Aa. The outlet pipe  37  is arranged closer to the attachment plate  15  than the inlet pipe  35 . 
     Outward of the inlet-side oil passage  20 , an outwardly swelling part  38 A is formed in the sidewall part  12 Aa of the casing  12 A. Referring again to  FIG. 8 , it will be seen that the outwardly swelling part  38 A extends radially outwardly beyond the first outer case wall portion  40  so as to be disposed a second radial distance from the central axis C 3 , which is greater than the first radial distance at which the first outer case wall portion is situated. The outwardly swelling part  38 A is also spaced a second distance away from the outer edge portion  42  of the heat exchange core  13  so as to form a second channel portion  46  therebetween having a second depth which is greater than the first depth, whereby the size of the cooling water passage  23  is increased in the outwardly swelling part. 
     Further, the outwardly swelling part  38 A is arranged in the axial direction of the sidewall part  12 Aa so as to extend between a portion where the inlet pipe  35  is connected to the sidewall part  12 Aa and a portion where the outlet pipe  37  is connected to the sidewall part  12 Aa. Specifically, as shown in  FIG. 5 , the outwardly swelling part  38 A is elongated in the axial direction of the sidewall part  12 Aa. One end of the outwardly swelling part  38 A is situated in a location whose distance from the one end of the casing  12 A is substantially equal to A, defined as the distance from the one end of the casing  12 A to the portion where the inlet pipe  35  is connected to the sidewall part  12 Aa. The other end of the outwardly swelling part  38 A is situated in a location whose distance from the other end of the casing  12 A is substantially equal to B, defined as the distance from the one end of the casing  12 A to the portion where the outlet pipe  37  is connected to the sidewall part  12 Aa. The longitudinal opposite end portions of the outwardly swelling part  38 A have arcuate curve surfaces. 
     Next, descriptions will be provided on the operation of the present invention according to a first illustrative embodiment. The outwardly swelling part  38 A is formed in the sidewall part  12 Aa of the casing  12 A outward of the inlet-side oil passage  20 . For this reason, in a location corresponding to the inlet-side oil passage  20 , the interval between the inner surface of the sidewall part  12 Aa of the casing  12 A and the outer periphery of the heat exchange core  13  can be set larger than in a case where the outwardly swelling part  38 A would not be formed. Thus, it is possible to increase the cross-section area of passage of the cooling water, and accordingly to decrease the flow rate of the cooling water. This makes it unnecessary that the interval between the outer periphery of the heat exchange core  13  and the inner periphery of the casing  12 A should be set larger throughout the circumference, and that the inlet-side oil passage  20  should be arranged spaced away from the inner surface of the casing  12 A. This makes it possible to avoid the oil cooler being constructed in a large size, and to avoid decreasing the heat exchange efficiency, as well as concurrently to prevent cavitation and erosion from occurring due to the flow of the cooling water in the area corresponding to the inlet-side oil passage  20 . 
     In addition, in a plan view projected onto the plane orthogonal to the axis of the sidewall part  12 Aa of the casing  12 A, the cooling water inlet passage  34  and the cooling water outlet passage  36  are distributed to, and arranged on opposite sides of the straight line L 1  passing through the axis C 1  of the inlet-side oil passage  20  and the axis C 2  of the outlet-side oil passage  21 . This arrangement makes it possible to cause the cooling water introduced to the inside of the casing  12 A to flow in the casing  12 A more effectively than in an arrangement in which both the cooling water inlet passage  34  and the cooling water outlet passage  36  would be arranged in one of the two sides of the straight line L 1 . 
     Furthermore, the inlet pipe  35  forming the cooling water inlet passage  34  and the outlet pipe  37  forming the cooling water outlet passage  36  are arranged spaced away from each other in the axial direction of the sidewall part  12 Aa. In addition, the outwardly swelling part  38 A is arranged in the axial direction of the sidewall part  12 Aa so as to extend between the portion where the inlet pipe  35  is connected to the sidewall part  12 Aa and the portion where the outlet pipe  37  is connected to the sidewall part  12 Aa. These arrangements make it possible to arrange the outwardly swelling part  38 A in an area where the amount of cooling water flow is larger, and accordingly to avoid the outwardly swelling part  38 A being formed larger than necessary. This makes it possible to avoid the casing  12 A being constructed in a large size. 
     Moreover, the outwardly swelling part  38 A is formed so as to be longer in the axial direction of the sidewall part  12 Aa, and the longitudinal opposite end portions of the outwardly swelling part  38 A have arcuate curve surfaces. This makes it possible to prevent the cooling water flow from fluctuating around the boundary between the outwardly swelling part  38 A and the sidewall part  12 Aa in each of the longitudinal opposite end portions of the outwardly swelling part  38 A. 
       FIG. 6  shows the present invention according to a second illustrative embodiment. Components corresponding to those of the first illustrative embodiment are denoted by the same reference numerals, and are illustrated only. Detailed descriptions will be omitted for these components. 
     The inlet pipe  35  forming the cooling water inlet passage  34  communicating with the cooling water passage  23  and the outlet pipe  37  forming the cooling water outlet passage  36  communicating with the cooling water passage  23  are connected to a sidewall part  12 Ba of a casing  12 B in a way that, like in the case of the first illustrative embodiment, the inlet pipe  35  and the outlet pipe  37  are distributed to, and arranged on opposite sides of the straight line L 1  passing through the axis C 1  of the inlet-side oil passage  20  and the axis C 2  of the outlet-side oil passage  21  as seen in the plan view projected onto the plane orthogonal to the axis of the sidewall part  12 Ba. The outwardly swelling part  38 B is formed in the sidewall part  12 Ba of the casing  12 B in a location opposite to the cooling water inlet passage  34  with respect to the inlet-side oil passage  20 . 
     According to the second illustrative embodiment, the outwardly swelling part  38 B is formed in the sidewall part  12 Ba of the casing  12 B in the location opposite to the cooling water inlet passage  34  with respect to the inlet oil passage  20 . This arrangement makes it possible to effectively prevent cavitation from occurring by arranging the outwardly swelling part  38 B in an area corresponding to the inlet-side oil passage  20  where the flow of the cooling water coming in from the cooling water inlet passage  34  hits the inner surface of the sidewall part  12  B. 
       FIG. 7  shows the present invention according to a third illustrative embodiment. Components corresponding to those of the first and second illustrative embodiments are denoted by the same reference numerals, and are illustrated only. Detailed descriptions will be omitted for these components. 
     As seen in the plan view projected onto the plane orthogonal to the axis of the sidewall part  12 Ca of the casing  12 C, an outwardly swelling part  38 C is formed in the sidewall part  12 Ca over an area extending between points P 1  and P 2  at which a second straight line L 2  intersects the sidewall part  12 Ca. Here, the second straight line L 2  passes through the axis C 1  of the inlet-side oil passage  20 , and is orthogonal to a first straight line L 1  passing through the axis of the sidewall part  12 Ca and the axis C 1  of the inlet-side oil passage  20 . 
     The third illustrative embodiment makes it possible to form the outwardly swelling part  38 C in the sidewall part  12 Ca over an area in which the cavitation may occur, and thus to avoid forming the outwardly swelling part  38 C larger than necessary, as well as accordingly to avoid the casing  12  being constructed in a large size. 
     The foregoing descriptions have been provided for the illustrative embodiments of the present invention. However, the present invention is not limited to the above-described embodiments. Various design modifications may be made without departing from the spirit or scope of the present invention as set forth in the appended claims.