Title of Invention

"A COOLER FOR A WATER COOLED ENGINE"

Abstract

A pump attachment hollow 41 and a water jacket 45 are formed on a pair of left and right side surfaces opposite of a body 1 having a substantially cuboids shape when the body 1 is die-cast. The water jacket at the right side surface is covered by an inlet cover 2. The pump attachment hollow 41 of the left side surface also functions as part of the water jacket, and a pump body 43 of a water pump 40 is locked into this hollow to form a lid. An impeller 46 is made to face into the water jacket 45 through a water way 43a formed in a central part of the water pump 40. A driving portion of the water pump 40 protrudes into a chain chamber 32 is fixed by a cam chain cover 3 , and is driven by a cam chain 35.

Full Text

The present invention relates to a cooler for a water cooled engine. [Related Art] A general water cooled engine has a structure in which a cylinder block, a cylinder head and a cylinder head cover formed as individually cast, and are assembled by being stacked on top of one another. In this case, the cylinder head is cast using a gravity die-casting process, and it is normal to form a water jacket using a core. The forming of the cylinder block is also carried out adopting die-casting techniques, and the water jacket in this case is normally formed by die-casting in the direction of a cylinder shaft. In the case where the above described cylinder and cylinder head for use in a general water cooled engine are manufactured by casting, since the formation of a water jacket uses a core, the number of processes, and the number of people involved in the work is increased. Moreover, because this core is used and discarded, there is a lot of waste. Also, when the water jacket is formed by die-casting in the direction of the cylinder shaft, there is a need to consider cooling efficiency since the die for the water jacket must be in a thin elongated shape. As well as that, the portion of the water jacket that is long and thin is prone to molten metal flowing away, which means that it also becomes difficult to achieve component accuracy. With this type of die casting, there is a problem related to the die structure for forming a long thin oil jacket. Utility Model publication No. Hei. 5-17377 discloses an engine having an oil jacket that is generally opened sideways at the circumference of a cylinder and can be closed by attaching a separate cover from outside, Further, with respect to arrangement of a water pump, Japanese patent laid-open publication No. Hei. 4-269324 discloses a structure in which a water pump is attached to a side surface of a cylinder facing into a chain chamber covered by a cam chain cover, and a sprocket of the water pump is arranged on the same plane as a rotating surface of a cam chain. Japanese utility model laid-open publication No. Sho. 62-141621 discloses a similar structure a water pump is fitted inside an attachment portion provided at a side part of a cylinder facing a chain chamber, and the circumference of the water pump is fixed to a side surface of the cylinder with bolts. Japanese utility model laid-open publication No. Hei. 2-35926 discloses a structure in which a water pump is mounted from outside to a position on the edge of a cylinder head of a chain chamber, and a sprocket provided on the shaft of this pump is driven by a cam chain. Together with the driving of the sprocket, a tip of the pump shaft extending into the engine is supported by a side surface of the cylinder head. [Problems To Be Solved By The Invention] Even in the case where an oil jacket has been formed opening at the cylinder edge, as hovm in Utility model publication No. Hei. 5-17377 mentioned above, the oil (or water) jacket must be covered by a separate cover, and a water pump must also be provided separately. Moreover, if a water jacket is formed completely around the circumference of a cylinder a-die structure for that only is complicated, and there are a lot of post-processes. Also, in the case where the pump is driven by the cam chain, plumbing must be provided using a hose etc. between the water pump and the water jacket, in each of the above described examples, and this type of plumbing structure is also complicated. There has thus been a desire for a cooling device that simplifies the structure, reduces the number of components and assembly steps, etc. by making components multi-functional, and which can be made profitably and can simplify the plumbing structure. [Means For Solving The Problems] In order to solve the above problems, a first invention relates to a cooling device for a water cooled engine, provided with a cylinder slidably housing an engine piston, a water jacket encircling the circumference of the cylinder, and a water pump for causing cooling water to be forcibly circulated to the inside of the water jacket, wherein the water jacket has an opening on the cylinder side, an impeller of the water pump is caused to face into this opening, and the opening is covered by the body of the water pump. A second invention is the above described first invention, wherein a support section for a pump shaft attached to the impeller is provided on an outer circumference wall surface of the cylinder inside the opening. A third invention is the above described first invention, wherein the water jacket is formed using a pair of dies arranged in mutually opposite directions and sandwiching the cylinder therebetween in a direction orthogonal to axis of the cylinder. A fourth invention is the above described third invention, wherein a draft direction of the pair of dies is coincident with an axial direction of a cam shaft of the engine. A fifth invention is the above described first invention, wherein a water way is formed in the pump body for direct communication with the water jacket. A sixth invention is the above described fifth invention, wherein a guide section for guiding water to the water way is provided on a cover of the water jacket covering a portion of the water jacket that is different to the place where the water pump is provided. A seventh invention is the above described first invention, wherein the water jacket is formed by lateral die-casting, with part of the water jacket opened and faced into a chain chamber housing a cam chain arranged on a cylinder side, and a water pump, housed in this opening portion and having an impeller facing the water jacket, is arranged between the cam chain cover and the cylinder. An eighth invention is the above described seventh invention, wherein the guide portion into the waterway is provided on the pump body of the water pump. [Effects of the Invention] According to the first invention, the water pump can be utilized as a cover for the water jacket, because the water jacket opens toward the edge of the cylinder, an impeller of the pump faces this opening portion, and the opening portion of the water jacket is covered by the pump body of the water pump. As a result, it is possible to simplify the structure, and reduce the number of components and assembly steps, etc. by making components multifunctional, and make the device compact. As well as this, there is no need for plumbing, such as a hose etc., between the water pump and the water jacket. According to the second invention, since the support section is provided for the pump shaft that is attached to the impeller, at the outer 1 surface of the cylinder inside the opening section, the pump shaft can be supported inside the water jacket, and it is easy to arrange the impeller so as to face the water jacket. According to the third invention, since the water jacket is formed using a pair of dies arranged in mutually opposite directions and sandwiching the cylinder therebetween in directions orthogonal to the axis of the cylinder, it is possible to form the water jacket by die-casting from the edge of the cylinder, and because the core for forming the water jacket that is required in the conventional casting method can be done away with, the number of processes and the number of people involved in the work can be reduced. As well as that, in the case where the die-casting process is adopted, there is no need to consider cooling efficiency of the dies of the water jacket section, it is possible to improve the precision of the water jacket and improve the degree of freedom of the shape. According to the fourth invention, the draft direction of the pair of dies is coincident with the axial direction of the engine cam shaft, which means that the split structure of the dies becomes simple, and it becomes possible to form the cam chamber at the same time as forming the water jacket. According to the fifth invention, since a waterway is formed in the pump body for direct communication with the water jacket, it is easy to form the waterway to the water pump. According to the sixth invention, since a guide section for guiding water to the water way is provided on a cover of the water jacket covering a portion of the water jacket that is different to the place where the water pump is provided, it is possible to guide cooling water inside the water jacket smoothly to the water way for the pump, using this guide portion. According to the seventh invention, since part of the water jacket that has been formed by die-casting using a pair of left and right dies is opened and faced into a chain chamber housing a cam chain arranged on a cylinder side, and a water pump, housed in this opening portion and having an impeller facing the water jacket, is arranged between a cam chain cover and the cylinder, it is possible to make it function as a cover for the water jacket that has been formed by die stamping in the pump body of the water pump. According to the eighth invention, since the guide portion into the waterway is provided on a pump body of the water pump, it is possible to guide cooling water inside the water jacket smoothly to the water way for the pump, using this guide portion. Therefore, the present invention relates to a cooler for a water cooled engine, provided with a cylinder slidably housing an engine piston, a water jacket is encircling the circumference of the surface of the cylinder housing the engine piston and is formed in the cylinder, and a water pump is composed of an impeller causing cooling water to be forcibly circulated to the inside of the water jacket and a body of the water pump housing the impeller,characterized in that the water jacket has an opening on the cylinder side, an impeller of the water pump is disposed in the opening, and the opening is covered by the body of the water pump. [Brief Description Of The Accompanying Drawings] Fig. 1 is a cross sectional drawing of the whole engine in an embodiment of the invention. Fig. 2 is a drawing showing a right side surface with an inlet cover removed. Fig. 3 is a drawing showing a left side surface with a cam chain cover removed. Fig. 4 is a cross sectional drawing along line 4-4 in Fig. 1 . Fig. 5 is a cross sectional drawing of a body portion along line 5-5 in Fig. 1. Fig. 6 is a cross sectional drawing of the body portion. Fig. 7 is a drawing showing a connecting surface side of the inlet cover. Fig. 8 is a drawing showing a connecting surface side of the cam chain cover. Fig. 9 is a cross sectional drawing showing cast metal dies for the body portion. Fig. 10 is a cross sectional drawing of metal dies showing the method of forming the water jacket. [Embodiment of the present invention] An embodiment that has been applied to a 4-cycle water cooled low displacement engine for a small type motorcycle will be described below based on the drawings. Fig. 1 is a cross sectional drawing of the whole engine in an embodiment of the invention; Fig. 2 is a drawing showing a right side surface with an inlet cover removed; Fig. 3 is a drawing showing a left side surface with a cam chain cover removed; Fig. 4 is a cross sectional drawing along line 4-4 in Fig. 1; Fig. 5 is a cross sectional drawing of a body portion along line 5-5 in Fig. I; Fig. 6 is cross sectional drawing of a body; Fig. 7 is a drawing showing a connecting surface side of the inlet cover; Fig. 8 is a drawing showing a connecting surface side of the cam chain cover; Fig. 9 is a cross sectional drawing showing cast metal dies of the body portion; and Fig. 10 is a cross sectional drawing of metal dies showing the method of forming the water jacket. First of all, the schematic structure of this engine will be described using Fig. 1 to Fig. 8. This engine has a substantially cuboid body 1 that has been formed using a casting method such as die-casting of a suitable meta! such as aluminum alloy. The body 1 is attached with an impeller cover 2 and a cam chain cover 3 on its two substantially parallel side surfaces facing each other, and attached to a crankcase (not shown). The body 1 is formed by integrally casting a cylinder portion 5, housing a piston 4 connected to a crank shaft (not shown) through a connecting rod 4, and a head portion 8 having a cam chamber 7 housing a cam shaft 6 in a rotatable manner. In this application, a portion for covering a cam chamber 7 in the head portion 8 will be specially termed the head cover portion 9. For further convenience, for the respective surfaces of the body 1, a surface to which the impeller cover 2 is attached will be called the right side surface 10, a surface to which a cam chain cover 3 is attached will be called a left side surface 11 (Fig. 6), of two opposed surfaces interposed between the left and right side surface, a surface to which a radiator (to be described later) is attached will be called a front surface 21, and the other of the two opposed surfaces will be called a rear surface 13. Also, an external ceiling surface will be called a top surface 14 and a surface to which a crankcase is attached will be called a bottom surface 15 (refer to Fig. 15). in the cylinder portion 5, a cylinder 16 is formed from the bottom surface 15 in a length direction to a substantially central portion of the body 1, and a combustion chamber 17 formed at the head portion 8 side, being the innermost portion of the cylinder 16, communicates with an intake port 18 and an exhaust port 19. Combustion chamber 17 side openings of each port are opened or closed by an intake valve 20 and an exhaust valve 21. The axes Cl, C2 of each of the valves form a fixed valve including angle with respect to the cylinder axis C. Reference numerals 20a and 21a are stem holders. The intake port 18 communicates with an intake passageway 22 formed on an inlet cover 2. This intake passageway 22 extends to the outside diagonally along an extension of the intake port 18, and is connected to a carburetor (not shown in the drawings) via an inlet pipe 23. The exhaust port 19 is bent substantially at a right angle to the inlet port 18, and is connected an exhaust pipe 24 via its rear surface 13. In Fig. 2 and Fig. 3, reference numeral 29 is a spark plug. The driving of each valve is direct drive type, in which they are directly driven by cams 27, 28 via valve lifters 25, 26 provided on the ends of respective shafts. The cam shaft 6 constituting these cams 27, 28 is supported by bearings 30, 31 at both open ends .of a cam chamber 7 penetrating between the right side surface 10 and the left side surface 11 and having a tapered shape. Each sliding surface of the cams 27, 28 forms an anclined plane corresponding to respective sliding surfaces of the valve lifters 25, 26. A refueling section 6a is also formed between one end of the cam shaft 6 and the inlet cover 2. The other end of the cam shaft 6 protrudes into a chain chamber 32 formed between a cam chain cover 3 and the left side surface 11, and a cam sprocket 33 is attached to this protruding end by bolts 34. This cam sprocket 33 is linked to a drive sprocket provided on a crankshaft (not shown) via a cam chain 35. Cam peep holes 36 37 having substantially the same diameter as each of the valve lifters 25, 26, and the same axes as the valve shafts Cl and C2, are formed on extensions of each valve shaft Cl and C2 within the head cover portion 9, and caps 38, 39 for respectively opening and closing the cam chamber 7 are hermetically via seals, using screws. in the vicinity of the combustion chamber 17 of the body 1, a water pump 40 is housed in a circular pump attachment hollow 41 formed in a side wall facing the cam chain cover 3 of the body 1. The water pump 40 is liquid-tightly sealed in the circular pipe attachment hollow 41, using an O-ring 44, by fitting an outer surface of a flange 42 formed in part of a resin cover constituting the profile of the water pump 40. A pump body 43 covers a water jacket 45 partially opening into the pump attachment hollow 41, an impeller 46 is arranged at a central portion of the pump body 43 and is supported so as to rotate integrally with a pump shaft 47. Cooling water is taken into the middle of the core of the pump body 43 from a water way 43a opening directly into the water jacket 45. One end of the pump shaft 47 is rotatably supported by a boss 48 protruding from an outer surface of the cylinder 16. The other end of the pump shaft 47 crosses over the cam chain 35, and protrudes into the chain chamber 32. A magnet ring 49 is provided around the shaft 47. The shaft 47 with the magnet ring 49 is partially covered with a flange 42 and an integral resin cover, and forms a circular small diameter portion 50. A protruding end of this small diameter portion 50 is lockingly supported at a circular 51 hollow formed in the cam chain cover 3. As can be seen clearly in Fig. 3, the center of this small diameter portion 50 and the center of the flange 42 are different, and a locking hollow 51 having the same center as the small diameter portion 50, and a pump attachment hollow 41 having the same center as the flange 42, are on different centers. With the small diameter portion 50 in a state of being locked to the locking hollow 51, the flange 42 is locked to the pump attachment hollow 41, and the water pump 40 is fixed to the pump attachment hollow 41 by attaching a cam chain cover 3 to the left side surface 11 using bolts etc. , As is clear from Fig. 5, a sprocket 53 for the water pump having a magnet ring 52 integrally formed on an inner circumference side is provided on an outer circumference portion of the small diameter portion 50. The sprocket 53 is driven by the cam chain 35. A boss outer surface of the sprocket 53 is rotatably housed via a bearing' 54, inside a circular water pump housing 55 formed in the cam chain cover 3. If the magnet ring 52 is rotated integrally with the water pump sprocket 53, the magnet ring 49 inside the small diameter portion 50 is integrally rotated by magnetic coupling, and as a result the impeller 46 rotates via the pump shaft 47 integral with the magnet ring 49, and the water pump is put in a driven -state. A water outlet 56 and a water inlet 57 are formed in the front surface 12 of the body 1 so as to protrude sideways. The water outlet 56 is in the vicinity of the cam chain cover 3, and is in communication with an discharge path 58 provided on the pump body 43. The discharge path 58 is connected to a substantially arc-shaped passage 59 going around the circumference of the impeller 46 inside the pump body 43..The water inlet 57 is arranged in the vicinity of the inlet cover 2, and is connected to the water jacket 45. A return opening 61 and water main opening 62 of the radiator 60 directly and respectively communicate with the water outlet 56 and water inlet 57, and the return opening 61 connects the inside of the radiator 60 to an upper radiator 64 through a return passageway 63 extending in a straight line in the extension direction of the emission path 58. As shown in Fig. 6, valve lifter holes 84, 85 for housing each of the valve lifters 25, 26, and stem holder holes 86, 87 having a small diameter and extending so as to connect from the ends of the valve lifter holes 84, 85 to the inlet port 18 and the exhaust port 19, are formed in the head portion 8 of the body 1. Each of these holes runs along the axes of the valve shafts Cl and C2, and extensions of each valve shaft axes Cl and C2 extend orthogonally to the axis of the cam shaft 6 (the central axis of the cam chamber), and the cam peep holes 36, 37 are formed in the head cover portion 9 above these extensions. As shown in Fig. 7, a rectangular cooling water seal 65, a circular inlet seal 66 and a substantially P-shaped oil section seal 67 are formed in a connecting surface side of the inlet cover 2 attached to the right side surface of the body 1. Water, air-fuel-mixture and oil are separately sealed between the right side surface 10 and the inlet cover 2 by fitting the inlet cover 2 to the right side surface 10 of the body 1. Reference numeral 67 in Fig. 7 is a concave portion connecting an oilway 67a (see Fig. 5) to a main gallery (not shown), reference numeral 68 is an oil passageway for supplying oil to an oil supply section 6a (see Fig. 1 and Fig. 4) formed on the end of the cam shaft 6, and reference numeral 69 in Fig. 4 is a boss for attaching a spark plug 29. Fig. 9 shows the die structure for forming the body 1 shown in Fig. 1, and comprises a right die 70 for forming the right side surface 10 of the body 1, a left die 71 for forming the left side surface 11, a cylinder die 72 for forming the cylinder portion 16, and an upper die 73 for forming the top surface 14. As shown in Fig. 10, a front surface die 92 and a rear surface die 97 are also used in the formation of the front surface 12 and the rear surface 13, respectively. A protruding portion 74 equivalent to a portion- for receiving an end of the cam shaft is formed in the right die 70, as well as a protruding portion 75 for forming a lower hole 18a equivalent to part of the inlet port 18 and a protruding portion 76 etc. equivalent to the water jacket 45 at the inlet cover 2 side. . A tapered protruding portion 77, for forming the cam chamber by casting, a pin 79 for forming a breather hole 78, and a protruding portion 80 equivalent to the pump attachment hollow 41 are formed in the left die 71, and a formation portion 81 equivalent to the boss 48 is formed in the middle of this protruding portion 80. A protruding portion 82 equivalent to the lower hole 18b constituting part of the intake passage 18, and a protruding portion 83 equivalent to the lower hole 19a of the exhaust port 19 are formed in the cylinder die 72. Protruding portions 97 and 98 for forming the cam peep holes 36 and 37 at the same time by casting are provided in the upper die 73. After die-casting by closing these dies together, when each of the dies is opened up, the body 1 is taken out in a state having various surfaces and indentations and spaces formed. Particularly, the left side surface 11 of the body 1 is formed by the left die 71 to be opened to the left. At the same time, the cam chamber 7 is cast using the protruding portion 77 pulled in a direction which is parallel to the axis of the cam shaft 6. Also, as will be described later, the pump attachment hollow 41 and the left side portion of the water jacket 45 are also formed at the same time by casting. Subsequently, when a few machining processes are carried out, such as drilling and internal hole surface shaping for each of the lower holes (18a, 18, 19a) etc., and screw cutting of drill holes of the lifter holes 84, 84, and the valve stem holder holes 86, 87, and screw cutting of the peep holes 36, 37, the body 1 having the three major components of the cylinder portion 5, the head portion 8 and the head cover portion 9 covering up to the upper part of the cam chamber 7, is completed. Fig. 10 shows the die structure for forming the water jacket 45 section. The protruding portion 76 of the right die 70 and protruding portion 80 of the left die 71 are provided with semicircular arc-shaped formation surfaces 90, 91 having gaps to the extent of the thickness of the cylinder 16, so as to surround the cylinder die 72 like a ring. Casting pins 93 and 94 for casting the water outlet 56 and the water inlet 57, and a protrusion 96 for forming an intermediate concave portion 95, are provided on the front surface die 92. Reference numeral 97 is a back die. The formation surfaces 90, 91 form spaces for locking the guide portions 101, 102, 103 and 104 in the 4 nooks of the cylinder portion 5 surrounding the cylinder 16, as shown in Fig. 5. These guide portions 101, 102, 103 and 104 are rounded and substantially parallel to the outer surface of the cylinder 16. The guide portions 101 and 102 are formed projecting from the pump body 43, while the guide portions 103 and 104 are formed on the water jacket 45 side of the inlet cover 2. A water passageway 43a is defined between the guide portions 101 and 102 among the surfaces facing into the water jacket 45 of the pump body 43. A curved surface is also formed between the guide portions 103 and 104, and a surface of the inlet cover 2 defining the water jacket 45, forms a single guide surface 105. However, within this guide surface i 105 a portion in the vicinity of the water inlet 57 partially forms a flank 106 for forming enlarged spaces to smoothly guide water into the water jacket 45 from the radiator 60. Air-cooling fins 107 are integrally formed in an outer surface of the inlet cover 2. Next, the operation of the embodiment will be described. The water jacket 45 opens towards the pump attachment hollow 41 on the side surface of the cylinder portion 5, the water pump 40 is fitted in this pump attachment hollow 41, and the open portion of the water jacket 45 is covered by the pump body 43. This means that the pump body 43 of the water pump 40 can also function as a cover for covering the water jacket 45. As a result, it is possible to provide a simplified structure with a reduced number of components and a reduced number of assembly steps, by using multi-functional components. The flange 42 of the water pump 40 is also made circular, and an outer peripheral part of the flange 42 is fluid-locked to an outer wall portion of the pump attachment hollow 41 to seal with an O ring, which means that the structure for sealing between the water pump 40 and the pump attachment hollow 41 is simplified. Further, since the pump attachment hollow 41 faces into the chain chamber 32 and the water pump 40 is arranged between cam chain cover 3 and the cylinder 16, the water jacket 45 acts as a cover at the time of forming the water jacket by die-casting so as to open towards the chain chamber 32, and at the same time the water pump 40 is appropriately arranged so as to be driven by the cam chain 35. Still further, by attaching the cam chain cover 3 to the left side surface 11, it is possible to fix the water pump 40 to the pump attachment hollow 41 of the cylinder portion 5, which means that the fixing structure is simplified, there is no need for bolts specifically for fastening the water pump 40 and there is no need for surface pressure control. Moreover, the center of the small diameter portion 50 and the center of the flange 42 are made different, and respective centers of the locking hollow 51 and the pump attachment hollow 41, for locking the small diameter portion 50 and the flange 42 ,are also made different, which means that if the flange 42 is locked into the pump attachment hollow 40 with the small diameter portion 50 locked into the locking hollow 51, the water pump 40 can be located in the pump attachment hollow 42 which means that locating of components at. the time of attaching the water pump is simplified. Further, since the impeller 46 directly faces into the water jacket 45 via the water way 43a provided on the pump body 43, there is no need for plumbing between the water pump 40 and the water jacket 45, it is possible to reduce the number of component, and the cooling water pathways can be made compact. In addition, since the attachment portion 48 for the pump shaft 47 is provided on the outer surface of the cylinder portion 5 and faces into the water way 43a, the pump shaft 47 can be supported inside the water jacket 45, and the arranging of the impeller 46 so as to face into the water jacket 45 becomes easy. Also, since the guide portions and guide surface 101 to 105, for guiding water into the water way 43a, having a substantially arc shape and being substantially parallel to the outer circumference of the cylinder 16, are arranged on the pump body 43 and the inlet cover 2, cooling water inside the water jacket 45 is smoothly guided to the water way 43a using these guide portions and guide surface, and it becomes difficult for water to become trapped midway. Furthermore, since the air cooling fins 107 are integrally formed on the outer surface of the inlet cover 2 facing into the water jacket 45, the cooling efficiency can be improved. Still further, the water jacket 45 is formed in a lateral direction so as to open toward the cylinder section 5 using a pair of mutually oppositely arranged dies, namely the right die 70 and the left die 71, with the cylinder portion 5 sandwiched therebetween in a direction orthogonal to the cylinder shaft C. As a result, it is possible to do away with the cores thai are necessary when casting the water jacket 45 using a conventional casting method, the large number of processing steps required to make the cores and shaking out can be obviated, and the number of processes and the number of people required for the work can be reduced. Further, when die casting is adopted, there is no need to consider cooling efficiency with respect to the die for the water jacket, improve precision of the water jacket can be expected, and design freedom of the shape can be improved. Moreover, since formation of the water jacket 45 is die-cast using the right die 70 and the left die 71 in the direction of the axis of the cam shaft 6, manufacture of the dies is simplified, and it is possible to form the cam chamber 7 by die-casting at the same time as forming the water jacket. As well as this, at the same time as making the water jacket 45, the body 1 integrally constituting the three parts of the cylinder section 5, the head section 8 and the head cover section 9 covering up to the upper part of the cam chamber 7 can be made by die-casting using the dies, and since post processing for the body-l after casting is only simple machining processes, manufacturing efficiency of the body 1 can be improved. Since the surfaces formed by the dies are comparatively smooth and fine, finishing processing using these type of mechanical processes can often be done away with, and manufacture is more profitable. The present invention is not limited to the above described embodiments, and various modifications are possible. For example, the casting method does not have to be aluminum die casting, and it is possible to adopt other well known casting methods using sand molds, for example. [Description of the Numerals] 1:body 2: inlet cover 3: cam chain cover 5: cylinder portion 6: cam shaft 7: cam chamber 8: head portion 9: head cover portion 16: cylinder 32: chain chamber 35: cam chain 40: water pump 41: pump attachment hollow 42: flange 43: pump body 43a: waterway 45: water jacket 46: impeller WE CLAIM: 1. A cooler for a water cooled engine, provided with a cylinder (16) slidably housing an engine piston, a water jacket (45) is encircling the circumference of the surface of the cylinder (16) housing the engine piston and is formed in the cylinder, and a water pump (40) is composed of an impeller causing cooling water to be forcibly circulated to the inside of the water jacket (45) and a body (1) of the water pump (40) housing the impeller, Characterized in that The water jacket (45) has an opening on the cylinder (16) side, an impeller (46) of the water pump (40) is disposed in the opening, and the opening is covered by the body (1) of the water pump (40). 2. The engine as claimed in claim 1, wherein a support section for a pump shaft attached to the impeller (46) is provided on an outer circumference surface of the cylinder (16) in the opening. 3. The engine as claimed in claim 1, wherein the water jacket (45) is formed using a pair of dies arranged in mutually opposite directions and sandwiching the cylinders in a direction orthogonal to an axis of the cylinder (16). 4. The engine as claimed in claim 3, wherein a draft direction of the pair of dies is coincident with an axial direction of a cam shaft (6) of the engine. 5. The engine as claimed in claim 1, wherein a water way (43a) is formed in the pump body (43) for direct communication with the water jacket (45). 6. The engine as claimed in claim 5, wherein a guide section for guiding water to the water way (43a) is provided on a cover of the water jacket (45) covering a portion of the water jacket (45) different to the portion where the water pump (40) is provided. 7. The engine as claimed in claim 1, wherein the water jacket (45) is formed by lateral die-casting, with part of the water jacket (45) opened and faced into a chain chamber (32) housing a cam chain (35) arranged on a cylinder (16) side, and a water pump (40), housed in this opening portion and having an impeller (46) facing the water jacket (45), is placed between the cam chain cover (3) and the cylinder (16). 8. The engine as claimed in claim 7, wherein the guide portion into the waterway (43a) is provided on a pump body (43) of the water pump (40). 9. A cooler for a water cooled engine substantially as herein described with reference to the accompanying drawings.

Documents:

2489-del-1998-abstract.pdf

2489-del-1998-claims.pdf

2489-del-1998-correspondence-others.pdf

2489-del-1998-correspondence-po.pdf

2489-del-1998-description (complete).pdf

2489-del-1998-drawings.pdf

2489-del-1998-form-1.pdf

2489-del-1998-form-13.pdf

2489-del-1998-form-19.pdf

2489-del-1998-form-2.pdf

2489-del-1998-form-3.pdf

2489-del-1998-form-4.pdf

2489-del-1998-form-6.pdf

2489-del-1998-gpa.pdf

2489-del-1998-petition-137.pdf

2489-del-1998-petition-138.pdf

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