Title of Invention

A COOLING WATER SYSTEM FOR AN INTERNAL COMBUSTION ENGINE

Abstract

A cooling water system (44) for an internal combustion engine (4), comprises : inlet and outlet pipes (54, 56), connecting the engine and a radiator (46), said engine and radiator being disposed such that an engine-side highest cooling water position (Se) of the engine is lower in height than a radiator-side highest cooling water position (Sr) of the radiator, the intermediate portions of the inlet and outlet pipes being lower in height than the engine-side and radiator-side highest cooling water positions ; a degassing valve (66) disposed on said radiator at the radiator-side highest cooling water position, said valve being connected to a reserve tank (70) through an overflow pipe (68), with said reserve tank positioned higher than the radiator such that a lower cooling water position (L) of said reserve tank is in line with said radiator-side highest cooling water position (Sr) ; and, an engine-side degassing valve (74) disposed on a thermostat (60), positioned on the engine at the engine-side highest cooling water position, said engine-side degassing valve (74) being connected to the overflow pipe (60) through an engine-side overflow pipe (76).

Full Text

BACKGROUND OF THE INVENTION 1. Eield of the Invention : This invention relates to a cooling water system for an internal combustion engine. More particularly, it relates to a cooling water system for an internal combustion engine, designed to provide easy degassing inside the engine, and to quickly obviate air lock inside the engine. 2. Description of the Related Art : In several vehicles, there is provided) a cooling water system for cooling down an internal combustion engine at every section thereof by virtue of cooling water, thereby maintaining temperature of the engine at a proper level. In the cooling water system, a water pump forcedly circulates the cooling water through a water jacket. The water jacket is a cooling water pathway in the engine. A radiator cools down the heated cooling water. One such example of a cooling water system comprises a vehicle, an internal combustion engine and a transmission system. The engine is vertically disposed at a substantially central portion of the vehicle. The transmission is connected to the engine. A floor panel covers the engine and the transmission. -2- The engine is provided wfth a cooling water system. The cooling water system has a radiator provided in the vehicle in a forward direction of the engine' that is located at the substantially central portion of the vehicle. As a result, the radiator and the engine are disposed in the vehicle, and are spaced apart from. The cooling water system includes an inlet pipe and an outlet pipe as a cooling water circuit. The inlet pipe introduces the cooling water from the water jacket of the engine into the radiator. The outlet pipe guides the cooling water from the radiator into the water jacket. The inlet pipe is connected at one end to a thermostat and at the other end to the upper tank. The thermostat is disposed at a jacket outlet of the water jacket at an upper portion thereof. The outlet pipe is connected at one end to the lower tank and at the other end to a jacket inlet of the water jacket. The cooling water system has a degassing valve provided on the top of the upper tank. The degassing valve is connected to a reserve tank through an overflow pipe. When pressure in the cooling water circuit through the water jacket and the radiator exceeds a predetermined pressure during operation of the engine, -3- then the degassing valve is opened to allow the pressure to be released into the reserve tank through the overflow pipe, together with air that is present in the upper tank. Further, when the pressure in the cooling water circuit falls as a result of shrinkage of the coofing water upon shutdown of the engine, then the degassing pipe permits the cooling water to be drawn from the reserve tank into the upper tank through the overflow pipe. Examples of such cooling water systems are disclosed in published Japanese Patent Application Laid-Open No.7-19043 and published Japanese Model Utility Applications Laid-Open No.56-63815 and No.3-99829. In the cooling water system as disclosed in the above No. 7-19043, a thermostat housing is disposed adjacent to a water jacket outlet. The thermostat housing is connected to an upper tank of a radiator through an upper hose. The radiator is located at a position lower than the thermostat housing. A cooling water injection opening is provided on the top of the thermostat housing. The injection opening is openably plugged up with a pressure cap. In the cooling water system as disclosed in the above No.56-63815, a degassing pipe is positioned at an upper portion of a cooling liquid passage in an engine. There are further provided a stopcock and a control valve. The stopcock -4- opens and closes the degassing pipe. A spring urges the stopcock in a direction in which the stopcock is closed. The control valve is disposed below the stopcock. The stopcock and a flap of a reserve tank portion are connected together by means of a rope so as to permit the stopcock to be closed in opposition to the force of the spring when the flap is opened. (n the cooling water system as disclosed in the above No.3,-99829, an upper tank of a radiator and a cooling water pump outlet-side passage of an engine body are connected to a reserve tank through a vent pipe. Further, the reserve tank and a cooling water pump inlet pipe are connected together through a make-up pipe. In this cooling water system, the vent pipe for connecting the cooling water outlet passage to the reserve tank is positioned above a cooling water pump. In addition, the vent pipe and a cooling water pump inlet portion are connected to one another through an air vent valve so as to permit air to be released from the cooling water pump into the vent pipe through the air vent valve, and further to prevent backflow of cooling water from the vent pipe. In the cooling water system of the afore-described first example, the radiator is installed in the vehicle at a position in the forward direction of the engine, while the engine is disposed at a substantially centra! portion of the vehicle. As a result, the radiator and the engine are disposed in the vehicle and are spaced apart from one another. -5- In this cooling water system, the inlet and outlet pipes for intercommunicating the engine and the radiator are laid so as to avoid interfering with the floor panel. To this end, the pipe is formed by being bent in upward and downward directions so as to permit an intermediate portion of the pipe to be lower than the other portions thereof. The inlet pipe thus bent upward and downward causes an inconvenience in that the cooling water system has difficulties of introducing air into the upper tank from the water jacket in the engine. Further, since such air stays in a thermo-cap of the thermostat that is disposed on the top of the water jacket, another inconvenience arises in that the air expands at elevated temperature, thereby bringing about air lock that results in overheating. SUMMARY OF THE INVENTION In order to obviate the above-described inconveniences, the present invention provides a cooling water system for an internal combustion engine, said system comprising : inlet and outlet pipes, through which the engine disposed in a vehicle and a radiator are connected to each other, the radiator being positioned in the vehicle in a fonward direction of the engine, the engine and the radiator being disposed such that an engine-side highest cooling water position of the engine is lower in height than a radiator-side highest cooling water position of the radiator, the inlet and outlet pipes being located such that -6- respective intermediate portions of the pipes are lower in height than the engine-side and radiator-side highest cooling water positions ; a degassing valve disposed on the radiator at the radiator-side highest cooling water position, said. valve being connected to a reserve tank through an overflow pipe the reserve. tank being positioned higher than the radiator such that allower cooling water position of the reserve tank is located in line with the radiator-side highest cooling water position ; and, an engine-side degassing valve d[sposecl-on a thermostat, the thermostat being positioned on the engine at the engine-side highest cooling water positon, and the engine-side degassing vaIve being connected to the overflow pipe through an engine-side overflow pipe. The engine-side highest cooling water position is preferably a position at which a water jacket is located, the water jacket being provided in an intake manifold mounted on the engine. The valve-opening pressure on the engine-side degassing valve can be maintained at a pressure less than the valve-opening pressure on the degassing valve disposed on the radiator. In the cooling water system according to the present invention, the radiator has the degassing valve disposed thereon at the radiator-side highest cooling water position. The degassing valve is connected to the reserve tank through the overflow pipe. In addition, the engine-side degassing valve is disposed on the thermostat. The thermostat is positioned on the engine at the engine-side highest cooling water position. The engine-side degassing valve is connected to the overflow pipe throughthe engine-side overflow pipe. As a -7- result, te engine-side degassing valve is opened, and then air remaining in the thermostat at the engine-side highest cooling water position can be guided into the reserve tank through both of the engine-side overflow pipe and the overflow pipe. This step can avoid air lock which otherwise would result from sJeh resident air. BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS In the accompanying drawings - Fig.1 is an enlarged side view, illustrating features of a vehrcle that houses a cooling water system for an internal combustion engine according to an embodiment of the present invention ; Fig.2 is a front view, showing the engine ; Fig.3 is a plan view, showing the engine ; Fig.4 is a side view, illustrating a vehicle with a conventional cooling water system for an internal combustion engine according to the prior art ; and, Fig.5 is an enlarged side view, illustrating essential portions of the vehicle of Fig.4. DESCRIPTION OF PRIOR ART One example of a known embodiment of a cooling system for an internal combustion engine will now be described with reference Figs. 4 and 5. In Fig.4, reference numeral 102 denotes a vehicle, 104 an internal combustion engine ; and, 106 a transmission system. The engine 104 is vertically disposed at a -8- substantially central portion of the vehicle 102. The transmission 106 is connected to the engine 104. A floor panel 108 covers the engine 104 and the. transmission 106. The engine 104 is provided with a cooling water system 110. As illustrated in Fig.5, the cooling water system 110 has a radiator 112 provided in the vehicle 102 in a forward direction of the engine 104 that is located . at the substantially central portion of the vehicle 102. As a result, the radiator 112 and the engine 104 are disposed in the vehicle 102 in a state of being spaced apart from one another. The radiator 112 includes an upper tank 114, a lower tank 116, and a core 118. The cooling water system 110 includes an inlet pipe 120 and an outlet pipe 122 as a cooling water circuit. The inlet pipe 120 introduces the cooling water from the water jacket (not shown) of the engine 104 into the radiator 112. The outlet pipe 122 guides the cooling water from the radiator 112 into the water jacket. The inlet pipe 120 is connected at one end to a thermostat 126 and at the other end to the upper tank 114. The thermostat 126 is disposed at a jacket outlet 124 of the water jacket at an upper portion thereof. The outlet pipe 122 is connected at one end to the lower tank 116 and at the other end to a jacket inlet 128 of the water jacket. -9- The cooling water system 110 has a degassing valve 130 provided on the top of the upper tank 114. The degassing valve 130 is connected to a reserve tank 134 through an overflows pipe 132. When pressure in the cooling water circuit through the water jacket and the radiator 112 exceeds a predetermined pressure during operation of the engine 104, then the degassing valve 130 is opened to allow the pressure to be released into the reserve tank 134 through the overflow pipe 132 together with air that resides in the upper tank 114. Further, when the pressure in the cooling water circuit falls as a result of shrinkage of the cooling water upon shutdown of the engine 104, then the degassing pipe 130 permits the cooling water to be drawn from the reserve tank 134 into the upper tank 114 through the overflow pipe 132. Examples of such cooling water systems are disclosed in Japanese Patent Application Laid-Open No.7-19043 and published Japanese Model Utility Applications Laid-Open No.56-63815 and No. 3-99829, have already been described. In the cooling water system 110 for the engine 104 as illustrated in Figs.4 and 5, the radiator 112 is installed in the vehicle 102 at a position in the forward direction of the engine 104, while the engine 104 is disposed at a substantially -10- central portion of the vehicle 102. As a result, the radiator 112 and the engine 104 are disposed in the vehicle 102 In a state of being spaced apart from one another. In the cooling water system 110, the inlet and outlet pipes 120, t22 for intercommunicating the engine 104 and the radiator 112 are laid so as to, avoid interfering with the floor panel 108. To this end, the pipe 120 is formed.by being bent in upward and downward directions so as to permit an intermediate portion of the pipe 120 to be lower than the other portions thereof. The inlet pipe 120 thus bent upward and downward causes an inconvenience in that the cooling water system 110 has difficulties of introducing air into the upper tank 114 from the water jacket in the engine 104. Further, since such air stays in a thermo-cap 136 of the thermostat 126 that is disposed on the top of the water jacket, another inconvenience arises in that the air expands at elevated temperature, thereby bringing about air lock that results in overheating. The present invention has been devised to overcome these problems. DESCRIPTION OF THE PREFERRED EMBODIMENTS Figs.1-3 illustrates one embodiment. In Fig.1, reference numeral 2 denotes a vehicle ; 4 an internal combustion engine ; and, 6 a transmission system. As illustrated in Figs.2 and 3, the engine 4 is vertically disposed and -11- slanted at a substantially central portion of the vehicle 2. The transmission 6 is connected to the engine 4. A floor panel 8 covers the engine 4 and the transmission 6. The engine 4 has a cylinder head 12 disposed on the top of a cylinder block 10, a head cover 14 provided on the cylinder head 12, an oil pan l6 mounted on the cylinder block 10. The engine 4 further has an intake manifold 18 mounted on the cylinder head 12 at an upward slant and a throttle-body 20 arranged in series with the intake manifold 18. The intake mari'tfold 18 is provided at a maximum height position of the engine 4. The engine 4 has a timing belt cover 22 mounted on the front thereof for covering a timing belt (not shown) and a crank pulley 26 disposed on a crankshaft 24. The crankshaft 24 protrudes from the timing belt cover 22. An auxiliary machine-driving belt 28 is wrapped around the crank pulley 26. The belt 28 is entrained around a pump pulley 30 of a water pump (not shown) and an alternator pulley 34 of an alternator 32. -12- In Figs. 2 and 3, reference numerals 36. 38, 40, and 42 denote a fuel injection valve, a delivery pipe, an exhaust manifold, and an exhaust supercharger, respectively. As shown in Fig. 1. the engine 4 is provided with a. cooling water system 44. The cooling water system 44 has a Ta-diator 46 positioned in the vehicle 2 in a forward direction of the engine 4 that is disposed at the substantially central portion of the vehicle 2. As a result, the engine 4 and the radiator 46 are disposed in the engine 4 in a state of being spaced apart from one another. The radiator 46 includes an upper tank 48, a lower tank 50, and a core 52. The cooling water system 44 includes an inlet pipe 54 and an outlet pipe 56 as a cooling water circuit. The inlet pipe 64 introduces cooling water from a water jacket (not shown) of the engine 4 into the radiator 46. The outlet pipe 56 guides the cooling water from the radiator 46 into the water jacket. The engine 4 has a thermostat 60 provided at a jacket outlet 58 of the water jacket (not shown). The water jacket (not shown) is provided in the intake manifold 18 that is positioned at the maximum height position of the engine 2. The cylinder block 10 is provided with a jacket inlet 62 of the water jacket. The inlet pipe 54 is communicated at one end to a the.rmo-cap 64 of the thermostat 60 and at the other end to the upper tank 48. The thermostat 60 is disposed at the jacket -13- r outlet 58 that is located at engine-side highest cooling water position" Se". The outlet pipe 56 is communicated at one end to the lower tank 50 and at the other to the jacket inlet 62. In the cooling water system 44, the engine 4 and the radiator 46 are disposed in such a manner that the aforesaid position "Se" is lower than the upper tank 48 that is positioned at radiator-side highest cooling water position "Sr." In addition, the cooling water system 44 has the inlet and outlet pipes 54, 56 arranged bent in upward and downward directions of the vehicle 2 so as to permit respective intermediate portions of the inlet and outlet pipes 54, 56 to be lower than the above positions "Se" and "Sr." As illustrated in Fig. 1, the cooling water system 44 has a degassing valve 66 provided on the top of the upper tank 48 that IS located at position "Sr." The valve 66 is communicated to a reserve tank 70 through an overflow pipe 68. The reserve tank 70 is provided higher than the upper tank 48 in such a manner that lower cooling water position "L" is positioned in line with position "Sr." The reserve tank 70 is provided with an exhaust pipe 72. When pressure in the cooling water circuit through the water jacket and the radiator 46 exceeds a predetermined pressure during operation of the engine 4, then the degassing valve 66 is opened to allow the pressure to be released into the reserve tank 70 through the overflow pipe 68, together with air - 14 - that resides in the upper tank 48. Further, when the pressure in the cooling water circuit falls as a result of shrinkage of cooling water upon shutdown of the engine 4. then the degassing pipe 66 permits the cooling water to be drawn from the reserve tank 70 into the upper tank 48 through the overflow pipe 68. The engine 4 has an engine-side degassing valve 74 disposed on the top of the thermo-cap 64 of the thermostat 60 that is positioned at position "Se." The degassing valve 74 is communicated to the overflow pipe 68 at a substantially midway portion thereof through an engine-side overflow pipe 76. First valve-opening pressure "p1" opens the degassing valve 66. A second valve-opening pressure "P2" opens the engine-side degassing valve 74, In the cooling water system 44, second valve-opening pressure "P2" is established to be less than first valve-opening pressure "Pi" (P2 Next, the operation of the embodiment will be described. In the cooling water 44, the crankshaft 24 drives a water pump (not shown) when the engine 4 is driven into operation. Then, cooling water is circulated between the water jacket of the engine 4 and the radiator 46 through the inlet and outlet pipes 54, 56. - 15 - The cooling water system 44 has the degassing valve 66 provided on the top of the upper tank 48 that is positioned at radiator-side highest cooling water position "Sr." The degassing valve 66 is communicated to the reserve tank 70 through the overflow pipe 68. The cooling water system 44 further has the engine-side degassing valve 74 disposed on the top of the thermo-cap 64 that is located at engine-side highest cooling water position "Se." The degassing valve 74 is communicated to the overflow pipe 68 at a substantially midway portion thereof through the engine-side overflow pipe 76. Further, in the cooling water system 44, second valve-opening pressure "P2" on the valve 74 is established to be less than first valve-opening pressure "P1" on the valve 66 (P2 Thus, the cooling water system 44 is designed to permit the valve 74 to be opened before pressure on the water jacket reaches first valve-opening pressure "P1" that opens the valve 66. The opened valve 74 allows air lodged in the thermo-cap 64 at position "Se" to be introduced rapidly into the reserve tank 70 through the overflow pipes 76 and 68. As a result, air lock can be avoided, which otherwise would result from the resident air in the engine 4. Consequently, the cooling water system 44 facili- - 16 - tates degassing inside the engine 4. and quickly overcomes the air lock inside the engine 4, thereby making it possible to avoid a likelihood of occurrence of overheat. Further, even when a pool of stagnant air occurs in the engine 4, and then air in the pool expands to drive the cooling water out of the engine 4, the degassing valve 74 allows a reduced amount of the cooling v/ater to be expelled from the engine 4. As a result, the cooling water can be prevented from jetting from the exhaust pipe 72, According to the above embodiment, the degassing valve 66 is disposed on the upper tank 48, while the engine-side degassing valve 74 is provided on the top of the thermo-cap 64. Alternatively, only the degassing valve 74 may stay in service. while the degassing valve 66 is eliminated. As a result, a cost cutback is achievable. Further, according to the above embodiment, degassing vale 74 is provided on the top of the thermo-cap 64 in a state of being communicated to the reserve tank 70 through the overflow pipe 68 by means of the engine-side overflow pipe 76. Alternatively, an engine-side reserve tank (not shown) dedicated to the degassing valve 74 may be disposed adjacent to the engine 4. Such an alternative step does not involve the need to extend the overflow pipe 76 up to the radiator 46, and uncomplicated piping is realized. Moreover, the degassing valve 74 may be constructed - 17 - to block an outflow of the cooling water while permitting only air to be released. As a result, the engine-side overflow pipe 76 can be eliminated. As evidenced by the above, in the cooling water sys-tern according to the present invention, the engine-side degassing valve is opened to allow air lodged in the thermostat at the engine-side highest cooling water position to be introduced into the reserve tank through both of the engine-side overflow pipe and the overflow pipe. Consequently, theair lock can be avoided, which otherwise would occur as a result of the resident air in the engine. Consequently, the cooling water system facilitates degassing in the engine, and quickly overcomes the air lock in the engine, thereby making it possible to avoid a likelihood of occurrence of overheat. -18 - WE CLAIM : 1. A cooling water system (44) for an internal combustion engine (4); said system comprising : inlet and outlet pipes (54, 56), through which the engine disposed in a vehicle and a radiator (46) are connected to each other, the radiator being positioned in the vehicle in a forward direction of the engine, the engine and the radiator being disposed such that an engine-side highest cooling water position (Se) of the engine is lower in height than a radiator-side highest cooling water position (Sr) of the radiator, the inlet and outlet pipes being located such that respective intermediate portions of the pipes are lower in height than the engine-side and radiator-side highest cooling water positions ; a degassing valve (66) disposed on the radiator at the radiator-side highest cooling water position, said valve being connected to a reserve tank (70) through an overflow pipe (68), the reserve tank being positioned higher than the radiator such that a lower cooling water position (L) of the reserve tank is located in line with the radiator-side highest cooling water position (Sr); and, an engine-side degassing valve (74) disposed on a thermostat (60), the thermostat being positioned on the engine at the engine-side highest cooling water position, and the engine-side degassing valve (74) being connected to the overflow pipe (68) through an engine-side overflow pipe (76). -19- 2. The cooling water system as claimed in claim 1, wherein the engine-side highest cooling water position is preferably a position at which a water jacket is located, the water jacket being provided in an intake manifold mounted on the, engine. 3. The cooling water system as claimed in claim 1, wherein the valve-opening pressure on the engine-side degassing valve can be maintained at a pressure less than the valve-opening pressure on the degassing valve disposed on the radiator. 4. A cooling water system for an internal combustion engine, substantially as herein described, particularly with reference to and as illustrated in the accompanying drawings. 5. An internal combustion engine incorporating a cooling water system as claimed in any one of claims 1 to 3. A cooling water system (44) for an internal combustion engine (4), comprises : inlet and outlet pipes (54, 56), connecting the engine and a radiator (46), said engine and radiator being disposed such that an engine-side highest cooling water position (Se) of the engine is lower in height than a radiator-side highest cooling water position (Sr) of the radiator, the intermediate portions of the inlet and outlet pipes being lower in height than the engine-side and radiator-side highest cooling water positions ; a degassing valve (66) disposed on said radiator at the radiator-side highest cooling water position, said valve being connected to a reserve tank (70) through an overflow pipe (68), with said reserve tank positioned higher than the radiator such that a lower cooling water position (L) of said reserve tank is in line with said radiator-side highest cooling water position (Sr) ; and, an engine-side degassing valve (74) disposed on a thermostat (60), positioned on the engine at the engine-side highest cooling water position, said engine-side degassing valve (74) being connected to the overflow pipe (60) through an engine-side overflow pipe (76).

Documents:

00893-cal-1999 abstract.pdf

00893-cal-1999 claims.pdf

00893-cal-1999 correspondence.pdf

00893-cal-1999 description[complete].pdf

00893-cal-1999 drawings.pdf

00893-cal-1999 form-1.pdf

00893-cal-1999 form-18.pdf

00893-cal-1999 form-2.pdf

00893-cal-1999 form-3.pdf

00893-cal-1999 form-5.pdf

00893-cal-1999 letter patent.pdf

00893-cal-1999 p.a.pdf

00893-cal-1999 priority document others.pdf

00893-cal-1999 priority document.pdf

893-CAL-1999-FORM-27.pdf