|Title of Invention||
"A COOLING DEVICE FOR INTERNAL COMBUSTION ENGINE"
|Abstract||The cooling device comprises: cooling water pipes 34 having opposite open ends and horizontally introducing cooling water; a pair of tanks 31 and 32 arranged at the opposite ends of the cooling water pipes 34 and communicating with each other; and radiating fins 33 extending vertically and being orthogonal to the cooling water pipes 34. [Selected Drawing]|
|Full Text||The present invention relates to a cooling device for internal combustion engine.
DESCRIPTION OF THE RELATED ART
Japanese Utility Model Laid-open Publication No. Sho 59-134777 exemplifies the ordinary structure of a cooling device, so-called '"radiator", for cooling cooling water circulating in a water-cooled internal combustion engine installed on a small vehicle like a motorcycle.
In this cooling device, a pair of tanks are arranged vertically. Substantially vertical cooling water pipes extend between a bottom opening of the upper tank and a top opening of the lower tank, thereby making the tanks communicative. A plurality of flat radiating fins are horizontally stacked on top of one another between the tanks with predetermined spaces kept therebetween, so that the cooling water pipes pass through the radiating fins. When the vehicle is in operation, wind blows in the running direction of the vehicle, and passes through the radiating fins, thereby cooling them. Therefore, the radiating fins cool cooling water flowing through the cooling water pipes.
|Problems to be solved by the Invention]
It is assumed here that the cooling device of the publication No. Sho 59-
134777 is downsized, and that radiating load per unit surface area of the
radiating fins is increased. In a normal running state, wind blows in the
running direction of the vehicle, advances along the opposite surfaces of the
radiating fins, and sufficiently cools cooling water in the cooling water pipes.
However, if the vehicle has to repeat to run at a low speed and stop because of
traffic congestion in summer, air blowing to the spaces between the radiating
fins tends to remain and is heated by the hot radiating fins, so that no heat
exchange is executed between blowing air and the cooling.
water in the cooling water pipes. This means that cooling efficiency of the cooling device is extensively reduced.
[Means of Means to Solve the problems and Effects]
Accordingly, there is provided a cooling device attached to a water-cooled internal combustion engine, comprising
cooling water pipe having open both ends introducing cooling water;
a pair of cooling water tanks at said both ends of said cooling water pipes and
communicating with each other via said cooling water pipes;
and radiating fins attached therein said cooling water pipes
characterized in that
said cooling water pipe is disposed horizontally
said radiating fins attached across said cooling water pipes with radiating
surface thereof orthogonally facing said cooling water pipes.
The cooling device of claim 1 has the foregoing structure. Therefore, even if
airstreams generated by the running vehicle or a cooling fan are reduced or
interrupted, air present between the radiating fins circulates upward along the
surfaces thereof across which the cooling water pipes extend. Therefore, this
natural convection enhances radiation of heat from the radiating fins, thereby
promoting heal exchange between outside air and the radiating fins and
cooling water in the cooling water pipes, and preventing extensive reduction of
the cooling efficiency.
According to the feature in claim 1, the cooling device can maintain its cooling efficiency even when there is no forced air flow generated because of the absence of a cooling fan. In other words, the cooling fan is not always necessary. This is effective in making the cooling device compact and light in weight and less expensive.
When the cooling device is configured as in claim 2, air in a space both of or either above or below upper or lower edges of each stacked radiating fin and
air in each vertical space
sandwiched between adjacent radiating fins is mixed, which promotes natural convection between the juxtaposed radiating fins, and smooth heat exchange between outside air and cooling water in the cooling water pipes. This improves cooling efficiency of the cooling device. 
The water-cooled internal combustion engine may be structured as in claim 3. In this case, a pair of cooling water tanks are reliably supported by the cylinder of the internal combustion engine, and are made resistant to vibrations. Further, the tanks can be positioned as close to the cylinder as possible, which is effective in shortening plumbing therebetween, and reducing flow resistance of cooling water circulating therein and load applied to the cooling water pump. 
In the water-cooled internal combustion engine having the structure defined in claim 4, the cooling device can be firmly attached thereto in order to improve vibration resistance. Further, the cooling device can dispense with a hose connecting the tanks and cooling water passage of the engine. This is effective in preventing leakage of water, making the cooling device less expensive, and downsizing the engine as a whole. 
The water-cooled internal combustion engine defined in claim 5 can prevent reduction of cooling efficiency of the cooling device even when outside air is heated by air which is heated by the cylinder and transmitted to an outer surface thereof.
[Brief Description of the Drawings]
Fig. 1 is a schematic perspective view of the internal combustion engine to which the cooling device according to the embodiment defined in claims 1 to 4 is applied.
Fig. 2 is a right side view of the engine in Fig. 1.
Fig. 3 is a longitudinal cross section taken along line Ill-Ill in Fig. 2.
Fig. 4 is a front view, observed in the direction IV in Fig. 2.
Fig. 5 is a left side view of the cooling device in Fie. 1.
Fig. 6 is a schematic perspective view of the engine to which the cooling device defined in claims 1 to 3 and 5 is applied.
[Description of Embodiment]
The invention will be described with reference to an embodiment defined in claims 1 to 4 and shown in Figs. 1 to 5. 
Fig. 1 is a schematic perspective view of an overhead type 4-cycle single cylinder internal combustion engine 1 to which the invention is applied. The engine 1 is installed on a vehicle
body between front and rear wheels of a small motorcycle (not
The internal combustion engine 1 comprises split left and right crankcases 2 and 3, a cylinder block 4, a cylinder head 5 and a cylinder head cover 6. The cylinder block 4 is placed on the crankcases 2 and 3 with the axis of a cylinder hole 7 extending substantially horizontally toward the front edges of the crankcases 2 and 3. The cylinder head 5 and cylinder head cover 6 are stacked on top of one another in front of the cylinder block 4. The crankcases 2 and 3, cylinder block 4, cylinder head 5 and cylinder head cover 6 are coupled to one another in order to form an integral member. 
Referring to Fig. 3, a piston 8 is slidably fitted in the cylinder hole 7, a crankshaft 9 is rotatably supported by the left and right crankcases 2 and 3, and a connecting rod 12 has its opposite ends rotatably supported by the piston 8 and crankshaft 9 via a piston pin and a crank pin 11. Reciprocation of the piston 8 enables the rotation of the crankshaft 9 . 
An inlet port 14 and an outlet port 15 are formed on the cylinder head 5, communicating with a combustion chamber 13 at the top of the cylinder hole 7 . An intake valve 16 and an exhaust valve 17 are rotatably disposed in the inlet and outlet ports 14 and 15, respectively. 
The camshaft 18 is disposed adjacent to the tops of the intake and exhaust valves 16 and 17. The camshaft 18 is rotatably supported via bearings 19 between the cylinder head 5 and a camshaft holder 20, and has a driven sprocket 21 fitted to its left large diameter end 18a, as an integral part. An endless chain 23 (i.e. a transmission mechanism) extends between a drive sprocket 22 integral with the crankshaft 9 and the driven sprocket 21. The camshaft 18 is rotated at a speed which is half a rotating speed of the crankshaft 9. The intake
and exhaust valves 16 and 17 are opened or closed once each time
the crankshaft 9 rotates twice.
Referring to Figs. 2, 4 and 5, a radiator 30, the cooling device for cooling the internal combustion engine 1, is disposed on the cylinder block 4. The radiator 30 includes: left and right cooling tanks 31 and 32 (in Fig. 5, the left cooling water tank 31 is shown at the right side while the right tank 32 is shown at the left side); a plurality of juxtaposed flat radiating fins 33 which extend vertically in the running direction of the vehicle; and cooling water pipes 34 laid between inner walls of the cooling water tanks 31 and 32 and extending across the radiating fins 33 in the width direction of the vehicle. The cooling water pipes 34 are cylindrical, and are vertically arranged in three rows, or horizontally arranged in two or three rows . Cooling water inlet/outlet ports 35 are formed on bottoms 31a and 32a of the cooling water tanks 31 and 32 (Only the inlet/outlet port 35 on the bottom 31a of the cooling water tank 31 is shown in Fig. 6) . A connecting sleeve 38 extends downward to and is fitted in the inlet/outlet port 35. A detachable cap 39 is attached to the top of th3 cooling water tank 31. 
As shown in Fig. 3, the radiator support brackets 40 and 41 extend from the opposite sides of the cylinder block 4, and are provided with cooling water ways 42 and 43, respectively. The right cooling water way 43 communicates with a cylindrical cooling water jacket 44 surrounding the outer surface of the combustion chamber 13. Another cooling water jacket 45 is provided on the cylinder head 5, communicating with an open end of the cooling water jacket 44. Both of the cooling water jackets 44 and 45 are tapered inward from the contacting area of the cylinder block 4 and the cylinder head 5. 
A recess 18a is formed at the center of the left large diameter end 18a of the camshaft 18. A plurality of permanent.
magnets 24 are arranged on the inner surface of the recess 18b
with an equal space maintained therebetween.
The cooling water pump 50 operated by the camshaft 18 includes a pump casing 51, a pump cover 52, and an impeller 54 which is rotatably supported by the pump casing 51 and the pump cover 52 in a rotor housing 51a of the pump casing 51. A plurality of cylindrical permanent magnets 55 are integrally attached around a stem 54a of the impeller 54 via the rotor housing 51a. The magnets 55 correspond to that of the permanent magnets 24 of the camshaft 18. The magnets 55 and 24 constitute a magnetic coupling. The impeller 54 of the cooling water pump 50 is magnetically coupled to the camshaft 18, and is rotated in response to the rotation of the camshaft 18. 
An inlet section 56 of the cooling water pump 50 communicates, via a pipe 46, with the lower opening 42a of the cooling water way 42 of the left radiator support bracket 40 as shown in Fig. 6. A discharge section 57 of the cooling water pump 50 communicates with a discharge passage 58 (defined by the partition 51) of the pump cover 52. A passage 59 of the partition 51 which communicates with the discharge passage 53 and a passage 60 which communicates with the cooling water jacket 45 of the cylinder head 5 are water-tightly coupled to the opposite ends of a pipe 61. Cooling water in the left cooling water tank 31 of the radiator 30 is introduced into the cooling water pump 50 via the cooling water way 42, the pipe 46 and the inlet port 56. Cooling water pressurized by the impeller 54 is supplied to the cooling water jackets 44 and 45 via the discharge section 57, discharge passage 58, passage 59, pipe 61 and passage 60. 
An idler sprocket 25 (i.e. an idle pulley) is rotatably attached around the pipe 61 in order to engage with the endless chain 23. An idler sprocket 27 is positioned near the crankshaft 9 compared with the idler sprocket 25 and is
rotatably attached to the cylinder block A via a pin 26. Idler sprockets 28 and 29 are rotatably disposed near the crankshaft 9 in such a manner as to sandwich the endless chain 23 therebetween, as shown in Fig. 6. 
The cooling device according to the embodiment shown in Figs. 1 to 5 has the foregoing structure, and operates in the following manner. When the water-cooled internal combustion engine 1 is activated, the camshaft 18 is also rotated, and the impeller 54 magnetically coupled to the camshaft 18 is rotated. Cooling water in the left cooling water tank 31 is introduced into the inlet section 56 of the cooling water pump 50 via the inlet/outlet port 35, connecting sleeve 38, cooling water way 42 of the radiator support bracket 40, and pipe 46. Cooling water is then pressurized by the impeller 54, and is supplied to the cooling water jackets 45 and 44 via the discharge section 57 of the cooling water pump 50, discharge passage 58, passage 59, pipe 61 and passage 60. Cooling water in the water jackets 45 and 44 flows to the right cooling water tank 32 via the cooling water way 43 of the right radiator support bracket 41, returning to the left cooling water tank 31 via the cooling water pipes 34. In other words, cooling water circulates through the cooling system. 
When the motorcycle (not shown) is made to run, wind blows through the radiator fins 33 from the front part to the rear part of the vehicle, thereby cooling the radiator fins 33 heated by hot cooling water flowing through the cooling water pipes 34 . The cooled radiator fins 33 cool cooling water in the cooling water pipes 34. 
When the motorcycle stops or runs at a very slow speed, wind does not blow through the spaces between the radiating fins 33 of the radiator 30. However, air present between the radiating fins 33 is heated by the radiating fins 33 or cooling water pipes 34, and moves upwards without being affected by any
obstacle present between the upper and lower parts of the radiating fins 33. As a result, heated air between the radiating fins 33 undergoes smooth natural convection, which enables the radiating fins 33 to discharge heat and protects the internal combustion engine 1 against overheating. 
The radiating fins 33 can be cooled by natural convection without requiring a radiating fan. This reduces the cost of the cooling device. 
The cooling water pipes 34 are cylindrical, and provide relatively less resistance to wind blowing from the front part of the vehicle and convection between the tops and bottoms of the radiating fins. This is effective in maintaining the cooling efficiency of the cooling device at a high level during running and stopping of the vehicle. 
The left and right cooling water tanks 31 and 32 are firmly attached to the cylinder block 4 using the bolts 47 which are screwed into the radiator supports 40 and 41 via the flanges 36 and 37. This structure prevents large amounts of force from being applied to the joints between the cooling water tanks 31 and 32 and the cooling water pipes 34, thereby ensuring the radiator 30 remains durable. 
Further, since the cooling water tanks 31 and 32 of the radiator 30 are directly attached to the cylinder block 4, no other coupling members such as cooling water hoses are necessary except for the pipes 46 and 61. This is effective in reducing the number of components, the number of possible leakage points and cost of the cooling device, and improving liquid-tightness. Besides, the shortened cooling water way contributes to reduction of resistance applied thereto, and to making the cooling water pump 50 compact. 
The cylinder block 4 positioned under the radiator 30 is
protected against stones or the like which may hit during the
running of the vehicle.
The arrangement of the pipe 61 in the space defined by the endless chain 23 can minimize the distance between the cooling water pump 50 adjacent to the camshaft 18 and the cooling water jacket 45 on the cylinder head 5. This is also effective in shortening the water way of the cooling system. 
The idler sprocket 27 is rotatably supported by the pipe 61 without using any dedicated member therefor. 
In the embodiment shown in Figs. 1 to 5, the cylinder block 4, cylinder head 5 and cylinder head cover 6 are inclined forward, with the axis of the cylinder hole 7 oriented forward. Alternatively, the cylinder block 4, cylinder head 5 and cylinder head cover 6 may be maintained upright with the axis of the cylinder hole 7 also being upright. In this arrangement, the radiator 30 may be displaced to the left and mounted on the left crankcase 2. 
Fig. 6 shows an embodiment defined in claims I, 2 and 5. 
In the embodiment of Fig. 6, no obstacles block wind in front of and behind the radiator 30. Further, nothing blocks ascending air currents at the upper of the radiator 30. Therefore, wind and ascending air currents are introduced between the radiating fins 33 in order to cause heat radiation therefrom. Further, the radiator 30 can be protected by the crankcase 2 thereunder. Therefore, this embodiment is as effective as the embodiment shown in Figs. 1 to 5.
[Description of Reference Numerals]
1 ... water-cooled internal combustion engine, 2, 3 ... crankcases, 4 ... cylinder block, 5 ... cylinder head, 6 ... cylinder head cover, 7 ... cylinder hole, 8 ... piston, 9 ... crankshaft, 10 ... piston pin, 11 ... crank pin, 12 ... connecting rod, 13 ... combustion chamber, 14 ... inlet port, 15 ... exhaust port, 16 ... intake valve, 17 ... exhaust valve', 18 ... camshaft, 19 ... bearing, 20 ... camshaft holder, 21 ... driven sprocket, 22 ... drive sprocket, 23 ... endless chain, 24 ... permanent magnets, 25 ... idler sprocket, 26 ... pin, 27, 28, 29 ... idler sprockets, 30 ... radiator, 31, 32 ... cooling water tanks, 33 ... radiating fins, 34 ... cooling water pipes, 35 ... cooling water inlet/outlet port, 36, 37 ... flanges, 38 ... connecting sleeve, 39 ... cap, 40, 41 ... radiator supports, 42, 43 ... cooling water ways, 44, 45 ... cooling water jackets, 46 ... pipe, 47 ... bolts,
50 ... cooling water pump, 51 ... pump casing, 52 ... pump cover, 53 ... rotary shaft, 54 ... impeller, 55 ... permanent magnet, 56 ... inlet section, 57 ...discharge section, 58 ... discharge passage, 59, 60 ... passages, 61 ... pipe.
1. A cooling device attached to a water-cooled internal combustion
cooling water pipe having open both ends introducing cooling
a pair of cooling water tanks at said both ends of said cooling
water pipes and communicating with each other via said cooling
and radiating fins attached therein said cooling water pipes
characterized in that
said cooling water pipe is disposed horizontally
said radiating fins attached across said cooling water pipes with radiating surface thereof orthogonally facing said cooling water pipes.
2. The cooling device as claimed in claim 1, wherein said cooling
water pipes pass through each of said juxtaposed radiating fins,
and each of said radiating fins has both upper and lower edges
thereof exposed at both lower and upper spaces, or either a lower
or upper edge thereof exposed in either a lower or upper space.
3. The cooling device as claimed in claim 1 or 2, wherein flanges are
integrally formed at lower parts of said cooling water tanks, and
are attached to a cooling water inlet/outlet port of said engine.
4. The cooling device as claimed in claim 1 or 2, wherein said cooling
device is arranged on a side of said cylinder of said engine, said
cylinder having the axis thereof extending vertically.
5. A cooling device for a water-cooled internal combustion engine
substantially as hereinbefore described with reference to the
|Indian Patent Application Number||2186/DEL/1998|
|PG Journal Number||10/2008|
|Date of Filing||27-Jul-1998|
|Name of Patentee||HONDA GIKEN KYOGO KABUSHIKI KAISHA|
|Applicant Address||1-1 MINAMIAYOYAMA 2-CHOME, MINATO-KU, TOKYO, JAPAN|
|PCT International Classification Number||F01P 7/16|
|PCT International Application Number||N/A|
|PCT International Filing date|