Patent Publication Number: US-7216611-B2

Title: Cooling structure of cylinder block

Description:
The disclosure of Japanese Patent Application No. 2004-067871 filed on Mar. 10, 2004, including the specification, drawings and abstract is incorporated herein by reference in its entirety. 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The invention relates to a cooling structure of a cylinder block, and more particularly to a cooling structure of a cylinder block which makes it possible to uniformly cool a bore wall of the cylinder block. 
     2. Description of the Related Art 
     A conventional cooling structure of a cylinder block is disclosed, for example, in Japanese Patent Laid-Open Publication No. 2002-30989. 
     The Japanese Patent Laid-Open Publication No. 2002-30989 discloses a technology in which the temperature of a bore wall is made uniform by providing a water jacket spacer inside a water jacket of a cylinder block of an internal combustion engine. However, the bore wall is overcooled in the vicinity of a coolant hole of a head gasket, and in the vicinity of portions connected to bypass pipes (e.g., an oil cooler, an automatic transmission fluid cooler, and a turbo cooler). This is because a flow speed of coolant in an inner wall of the water jacket becomes high in the vicinity of the coolant hole and in the vicinity of the portions connected to the pipes through which the coolant flows in and flows out of the cylinder block. 
     Accordingly, in the conventional cooling structure of a cylinder block, it is difficult to uniformly cool the bore wall. 
     SUMMARY OF THE INVENTION 
     In view of the above, it is an object of the invention to provide a cooling structure of a cylinder block which makes it possible to uniformly cool the cylinder block. 
     An aspect of the invention relates to a cooling structure of a cylinder block, in which a temperature of a bore wall is made uniform using a cooling medium. The cooling structure of a cylinder block includes a water jacket portion which is provided so as to surround an entire outer periphery of the bore wall and which is supplied with the cooling medium; a water jacket spacer which is inserted in the water jacket portion; and a gasket which is provided in an upper portion of the cylinder block, and which includes a hole leading to the water jacket portion. In the cooling structure of a cylinder block, a distance between a center of the hole and an outer periphery of the cylinder block is shorter than a distance between a center of the water jacket spacer in a thickness direction and the outer periphery of the cylinder block. 
     In the aforementioned cooling structure of a cylinder block, the distance between the center of the hole (coolant hole) formed in the gasket and the outer periphery of the cylinder block is shorter than the distance between the center of the water jacket spacer in the thickness direction and the outer periphery of the cylinder block. Therefore, for example, when the cooling medium flows from an engine head portion into the water jacket portion of the cylinder block through the hole of the gasket, the cooling medium flows into a space between the water jacket spacer and a side opposite to the bore wall. Thus, this cooling structure is effective for preventing overcooling of the bore wall. Accordingly, the cylinder block can be uniformly cooled. 
     Another aspect of the invention relates to a cooling structure of a cylinder block, in which a temperature of a bore wall is made uniform using a cooling medium. The cooling structure of a cylinder block includes a water jacket portion which is provided so as to surround an entire outer periphery of the bore wall and which is supplied with the cooling medium; a water jacket spacer which is inserted in the water jacket portion; a bypass passage which is provided in the cylinder block, and which connects the water jacket portion to equipment; and a flow rate control mechanism which is provided in the vicinity of the bypass passage, and which reduces a flow rate of the cooling medium in a space between the water jacket spacer and the bore wall. 
     In the aforementioned cooling structure of a cylinder block, since the flow rate control mechanism is provided in the vicinity of the bypass passage, it is possible to reduce the flow rate of the cooling medium flowing along a surface of the water jacket portion on the bore wall side. As a result, the bore wall can be prevented from being overcooled, and the cylinder block can be uniformly cooled. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The above mentioned and other objects, features, advantages, technical and industrial significance of this invention will be better understood by reading the following detailed description of exemplary embodiments of the invention, when considered in connection with the accompanying drawings, in which: 
         FIG. 1  is a cross sectional view showing a cooling structure of a cylinder block according to a first embodiment of the invention; 
         FIG. 2  is a cross sectional view showing a cooling structure of a cylinder block according to a comparative example; 
         FIG. 3  is a cross sectional view showing the cooling structure of a cylinder block according to the first embodiment of the invention; 
         FIG. 4  is a cross sectional view showing the cooling structure of a cylinder block according to the comparative example; 
         FIG. 5  is a plan view showing a cooling structure of a cylinder block according to a second embodiment of the invention; 
         FIG. 6  is a cross sectional view taken along line VI—VI in  FIG. 5 ; 
         FIG. 7  is a front view showing a water jacket spacer seen in a direction shown by an arrow VII in  FIG. 6 ; 
         FIG. 8  is a cross sectional view showing the cooling structure of a cylinder block according to the comparative example; 
         FIG. 9  is a cross sectional view showing a cooling structure of a cylinder block according to a second embodiment of the invention; and 
         FIG. 10  is a cross sectional view showing the cooling structure of a cylinder block according to the comparative example. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     In the following description and the accompanying drawings, the present invention will be described in more detail with reference to exemplary embodiments. 
     Hereinafter, exemplary embodiments of the invention will be described with reference to the accompanying drawings. In the embodiments, the same portions or equivalent portions are denoted by the same reference numerals, and duplicate description thereof will be omitted. 
       FIG. 1  is a cross sectional view showing a cooling structure of a cylinder block according to a first embodiment of the invention. As shown in  FIG. 1 , a cooling structure  1  of a cylinder block according to the first embodiment includes a cylinder block  10  including a water jacket portion  12  that is provided so as to surround an entire outer periphery of a bore wall  11   b ; a water jacket spacer  20  which is inserted in the water jacket portion  12 ; and a gasket  40  which is provided in an upper portion of the cylinder block  10 , and which includes a hole  41  leading to the water jacket portion  12 . The water jacket portion  12  is supplied with coolant 100 W that is a cooling medium, whereby the temperature of the bore wall  11   b  is made uniform. A distance between a center  41   c  of the hole  41  and an outer periphery of the cylinder block  10  is shorter than a distance between a center  20   c  of the water jacket spacer  20  in a thickness direction and the outer periphery of the cylinder block  10 . 
     The cylinder block  10  includes a cylinder liner assembly  11  which is provided inside the cylinder block  10 ; the water jacket portion  12  which is provided so as to surround the cylinder liner assembly  11 , and which serves as a cooling medium passage; and a cylinder block base portion  13  which surrounds the water jacket portion  12 , and which is opposed to the cylinder liner assembly  11 . 
     The cylinder liner assembly  11  is constituted by a cylinder liner that is made of iron; and aluminum alloy that surrounds the cylinder liner. The cylinder liner assembly  11  includes a bore region  11   h  in which a piston is inserted. The bore region  11   h  is a substantially cylindrical region. Plural bore regions  11   h  are arranged in one direction. 
     The number of the bore regions  11   h  is not limited to a specific number. The number of the bore regions  11   h  may be variously changed. The cylinder liner assembly  11  includes the bore wall  11   b . The bore wall  11   b  is cooled by the cooling medium (coolant 100 W) supplied to the water jacket portion  12 . Heat generated in the bore region  11   h  is dissipated from the bore wall  11   b  to the outside. 
     The water jacket portion  12  is provided between the cylinder liner assembly  11  and the cylinder block base portion  13 . The water jacket portion  12  serves as a passage through which the coolant 100 W that is the cooling medium flows. The water jacket portion  12  includes a bottom portion. The cylinder liner assembly  11  is connected to the cylinder block base portion  13  at the bottom portion of the water jacket portion  12 . The water jacket portion  12  is configured to have a substantially uniform width. That is, a distance between the bore wall  11   b  of the cylinder liner assembly  11  and the cylinder block base portion  13  is substantially uniform. 
     The cylinder block base portion  13  is made of aluminum alloy, and is formed by die casting or the like. The material used for forming the cylinder liner assembly  11  and the cylinder block base portion  13  is not limited to aluminum alloy. Thus, the cylinder liner assembly  11  and the cylinder block base portion  13  may be made of cast iron. The cylinder block base portion  13  serves as an engine block, and various auxiliary machines that need to be provided in an engine are fitted to the cylinder block base portion  13 . A piston  50  is provided in the bore region  11   h.    
     Further, as the cooling medium, various fluids such as water, long-life coolant, and oil can be used. 
     The water jacket spacer  20  is inserted in the water jacket portion  12 . The water jacket spacer  20  has a shape similar to a shape of the water jacket portion  12  such that the water jacket spacer  20  can be inserted in the water jacket portion  12 . Also, the water jacket spacer  20  is formed so as to surround the cylinder liner assembly  11 . The material used for forming the water jacket spacer  20  is not limited to a specific material. That is, as the material used for forming the water jacket spacer  20 , it is possible to use various materials, such as aluminum, cast iron, nonmetallic materials, inorganic materials, and organic materials. 
     Part of an upper portion of the water jacket spacer  20  is cut off. The upper portion of the water jacket spacer  20  is covered with a heat insulation material  19 . The heat insulation material  19  is in contact with both of the water jacket spacer  20  and the bore wall  11   b . That is, a small space having a width L between the water jacket spacer  20  and the bore wall  11   b  is closed by the heat insulation material  19  at one end. Thus, it is possible to suppress the flow of coolant in the small space between the water jacket spacer  20  and the bore wall  11   b.    
     A gasket  40  is provided on the cylinder block  10  in order to prevent leakage of the coolant, leakage of lubricating oil, and pressure loss. The gasket  40  may be made of metal. Also, the gasket  40  may be made of an inorganic material. The hole  41  is formed in the gasket  40 , and the hole  40  leads to the water jacket portion  12 . 
     An engine head  60  is provided on the gasket  40 . Various devices such as cams and valves are fitted to the engine head  60 . A head passage  61  for cooling the engine head  60  is provided in the engine head  60 . The coolant 100 W that is the cooling medium flows in the head passage  61 . Thus, the coolant 100 W can remove heat in the vicinity of the head passage  61 . 
     The hole  41  is formed in the gasket  40  such that the position of the hole  41  is deviated from the position of the space between the water jacket spacer  20  and the bore wall  11   b  when seen from above. That is, the position of the hole  41  does not overlap with the position of the space between the water jacket spacer  20  and the bore wall  11   b  when seen from above. Thus, the flow speed of the coolant is decreased at the bore wall  11   b.    
     An upper portion of the water jacket portion  12  is covered with the water jacket spacer  20  and the cylinder block base portion  13  in the vicinity of the hole  41  of the gasket  40 . The heat insulation material  19  is attached to the bore wall  11   b . A protrusion portion may be formed in the water jacket spacer  20  in order to suppress the flow of the coolant in the space between the water jacket spacer  20  and the bore wall  11   b . The width L of the space between the water jacket spacer  20  and the bore wall  11   b  is made smaller than a width of a space between the water jacket spacer  20  and the cylinder block base portion  13 . 
       FIG. 2  is a cross sectional view showing a cooling structure of a cylinder block according to a comparative example. As shown in  FIG. 2 , in the comparative example, the position of the center  41   c  of the hole  41  overlaps with the position of the center  20   c  of the water jacket spacer  20  when seen from above. Thus, the coolant is likely to flow into the space between the bore wall  11   b  and the water jacket spacer  20 , and therefore the bore wall  11   b  is overcooled. 
     In  FIG. 1  and  FIG. 2 , the coolant flows from the engine head  60  toward the cylinder block  10 . 
       FIG. 3  is a cross sectional view showing the cooling structure of a cylinder block according to the first embodiment of the invention. As shown in  FIG. 3 , since the hole  41  of the gasket  40  is formed close to the outer periphery of the cylinder block  10 , the coolant flows in the outer portion of the water jacket portion  12  as shown by arrows. Thus, it is possible to suppress the flow of the coolant in the space between the water jacket spacer  20  and the bore wall  11   b . As a result, the bore wall  11   b  can be prevented from being overcooled. 
       FIG. 4  is a cross sectional view showing the cooling structure of a cylinder block according to the comparative example. As shown in  FIG. 4 , since the position of the center  41   c  of the hole  41  overlaps with the position of the center  20   c  of the water jacket spacer  20  when seen from above, the coolant is likely to flow into the space between the water jacket spacer  20  and the bore wall  11   b . Thus, an active flow of the coolant occurs in the space between the bore wall  11   b  and the water jacket spacer  20  as shown by arrows, and the speed of this flow increases. As a result, the bore wall  11   b  opposed to the water jacket spacer  20  is overcooled. 
     As described above, in the cooling structure of a cylinder block according to the first embodiment of the invention, the bore wall  11   b  can be prevented from being overcooled. As a result, it is possible to prevent overcooling of a specific cylinder. Thus, the cylinder block can be uniformly cooled. 
       FIG. 5  is a plan view showing a cooling structure of a cylinder block according to a second embodiment of the invention.  FIG. 6  is a cross sectional view taken along line VI—VI in  FIG. 5 .  FIG. 7  is a front view showing the water jacket spacer seen in a direction shown by an arrow VII in  FIG. 6 . As shown in  FIG. 5 , after the coolant flows into the cylinder block  10  in a direction shown by an arrow  101 , the coolant flows in the water jacket portion  12 , and removes heat of the cylinder liner assembly  11 . Then, the coolant flows out through a bypass passage  14 . After the coolant flows out through the bypass passage  14 , the coolant flows into equipment  200  in  FIG. 6 , as shown by an arrow  102 . The equipment  200  includes an oil cooler, an automatic transmission fluid cooler (ATF cooler), and a turbo cooler. Thus, after the coolant flows out of the cylinder block  10  in the direction shown by the arrow  102 , the coolant flows into the equipment  200  including the oil cooler, the ATF cooler, and the turbo cooler. 
     The cooling structure  1  of a cylinder block according to the second embodiment of the invention includes the cylinder block  10  including the water jacket portion  12  that is provided so as to surround the entire periphery of the bore wall  11   b ; and the water jacket spacer  20  which is inserted in the water jacket portion  12 . The water jacket portion  12  is supplied with the coolant 100 W that is the cooling medium, whereby the temperature of the bore wall  11   b  is made uniform. The bypass passage  14  for connecting the water jacket portion  12  to the equipment  200  is provided in the cylinder block  10 . A flow rate control mechanism  22  is provided in the vicinity of the bypass passage  14 , and reduces the flow rate of the coolant in the space between the water jacket spacer  20  and the bore wall  11   b.    
     The flow rate control mechanism  22  is made of a heat insulation material. The flow rate control mechanism  22  reduces the flow rate of the coolant flowing to the bypass passage  14  thorough a concave portion  23  that is provided in the water jacket spacer  20 . As shown in  FIG. 7 , the water jacket spacer  20  includes an upper surface  20   t  and a bottom surface  20   b . Both of the upper surface  20   t  and the bottom surface  20   b  are in contact with the coolant 100 W. The flow rate control mechanism  22  has a U-shape, and is provided around the concave portion  23 . The flow rate control mechanism  22  is provided at the bottom portion of the water jacket portion  12 . The flow rate control mechanism  22  is in direct contact with the bore wall  11   b . The flow rate control mechanism  22  can be made of metal, nonmetal or resin such as foamed rubber and urethane. 
     In addition to providing the flow rate control mechanism  22 , the width of the space between the bore wall  11   b  and the water jacket spacer  20  is made small. 
     Thus, the flow rate control mechanism  22  reduces the flow rate of the coolant flowing to the bypass passage  14  through the concave portion  23 , and also reduces the flow rate of the coolant in the space between the water jacket spacer  20  and the bore wall  11   b , which is the region upstream of the flow rate control mechanism  22 . Accordingly, it is possible to prevent the bore wall  11   b  from being overcooled at this region. As a result, the bore wall  11   b  can be uniformly cooled. 
       FIG. 8  is a cross sectional view showing the cooling structure of a cylinder block according to the comparative example. As shown in  FIG. 8 , in the cooling structure  1  of a cylinder block according to the comparative example, the flow rate control mechanism  22  is not provided around the concave portion  23 . Therefore, a large amount of coolant 100 W flows to the bypass passage  14  through the concave portion  23 , as shown by arrows. Thus, the coolant flows in the space between the bore wall  11   b  and the water jacket spacer  20 , and the bore wall  11   b  is overcooled. 
       FIG. 9  is a cross sectional view showing the cooling structure of a cylinder block according to the second embodiment of the invention. As shown in  FIG. 9 , even when the coolant is supplied from the equipment  200  through the bypass passage  14  in the direction shown by the arrow  101 , since the flow rate control mechanism  22  is provided, it is possible to suppress the flow of the coolant in the space between the bore wall  11   b  and the water jacket spacer  20 . Accordingly, the bore wall  11   b  can be prevented from being actively cooled. That is, bore wall  11   b  can be prevented from being overcooled. As a result, the bore wall  11   b  can be uniformly cooled. 
       FIG. 10  is a cross sectional view showing the cooling structure of a cylinder block according to the comparative example. As shown in  FIG. 10 , in the comparative example, since the flow rate control mechanism  22  is not provided, a large amount of coolant 100 W flows through the concave portion  23 . Since the coolant 100 W flows in the space between the bore wall  11   b  and the water jacket spacer  20 , heat of the bore wall  11   b  is removed by the coolant 100 W. As a result, the bore wall  11   b  is overcooled. Meanwhile, according to the second embodiment of the invention, it is possible to reduce the flow rate of the coolant flowing along an inner surface of the bore wall  11   b  in the space between the water jacket spacer  20  and the bore wall  11   b , by attaching, to the inner surface of the bore wall  11   b , the flow rate control mechanism  22  that is made of a heat insulation material. 
     A protrusion portion may be formed in the water jacket spacer  20  in order to suppress the flow of the coolant in the space between the water jacket spacer  20  and the bore wall  11   b . Also, the width of the space between the water jacket spacer  20  and the bore wall  11   b  is made smaller than the width of the space between the water jacket spacer  20  and the cylinder block base portion  13 . 
     The embodiments of the invention have been described. Various modifications can be made to the aforementioned embodiments. The invention can be applied not only to a gasoline engine, but also to a diesel engine. Also, size of the engine is not limited to specific size, and the number of cylinders is not limited to a specific number. Further, the invention can be applied to various types of engines, such as an in-line engine, a V-type engine, a W-type engine, and a horizontal opposed engine. 
     While the invention has been described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the exemplary embodiments or constructions. To the contrary, the invention is intended to cover various modifications and equivalent arrangements. In addition, while the various elements of the exemplary embodiments are shown in various combinations and configurations, which are exemplary, other combinations and configurations, including more, less or only a single element, are also within the spirit and scope of the invention.