Patent Publication Number: US-6662789-B1

Title: Water-cooled exhaust gas recirculating device

Description:
TECHNICAL FIELD 
     The invention relates to a water-cooled exhaust gas re-circulation device disposed at an exhaust gas re-circulation passage of an internal combustion engine such as engines. 
     BACKGROUND ART 
     FIG. 1 illustrates a schematic representation of the whole of a conventional cooling water re-circulation passage arranged at the internal combustion engine. FIG. 2 is a front view of a water-cooled exhaust gas re-circulation device arranged at the conventional cooling water re-circulation of FIG.  1 . FIG. 3 is a cross sectional view taken along lines III—III of FIG.  2 . FIG. 4 is a cross sectional view of a hole formed at a part of the cooling water re-circulation passage within the water-cooled exhaust gas re-circulation device during a die casting. 
     In these drawings, a reference numeral  1  denotes a cooling water re-circulation passage, and a reference numeral  2  denotes a water-cooled exhaust gas re-circulation device arranged at the cooling water re-circulation passage  1 . A reference numeral  3  denotes a drain bolt independent of other components arranged at the cooling water re-circulation passage  1  close to a cylinder block and constituting a hole communicating the cooling water re-circulation passage  1  and outside air. A reference numeral  4  denotes a radiator preventing the cooling water re-circulated in the cooling water re-circulation passage  1  from increasing the temperature. A reference numeral  5  denotes a drain cock acting as an outlet of the cooling water when the cooling water is changed to new one. A reference numeral  6  denotes a radiator cap controlling an internal pressure of the cooling water re-circulation passage  1 . The radiator cap  6  constitutes an air hole, which is close to the radiator when the cooling water is changed to new one, and an inlet of the cooling water when the cooling water is supplied to the cooling water re-circulation passage  1 . A reference numeral  7  denotes a cylinder block constituting an external engine. A reference numeral  8  denotes a water pump arranged in the cooling water re-circulation passage  1  and supplying the cooling water to the cylinder block  7  of the engine in order to re-circulate it in the cooling water re-circulation passage  1 . 
     The water-cooled exhaust gas re-circulation device  2  includes a valve housing  10  including an exhaust gas re-circulation valve (not shown) and a motor main body  11  including a motor driving the exhaust gas re-circulation valve as shown in FIG.  2  and FIG.  3 . The motor main body  11  is affixed to the valve housing  10  with screws  12 . A reference numeral  13  denotes a terminal supplying electric power to the motor (not shown) arranged in the motor main body  11 . Reference numerals  14  and  15  denote inlet and outlet of an exhaust gas re-circulation passage, which is opened and closed due to the exhaust gas re-circulation valve. A reference numeral  16  denotes a nipple guiding the cooling water from the cooling water re-circulation passage  1 , which is close to the engine, to the cooling water re-circulation passage  1  within the water-cooled exhaust gas re-circulation device  2 . When the cooling water re-circulation passage  1  in the water-cooled is manufactured due to the die casting, it is necessary to form a hole  17  arranged at a part of the passage  1  as shown in FIG.  4 . With a conventional constitution, the hole  17  was filled with a plug  18  as shown in FIG.  3 . 
     With the cooling water re-circulation passage  1 , when the cooling water is changed to new one, the drain cock  5  arranged at a lower section of the radiator  4  is used as a discharge port of the cooling water and the radiator cap  6  mounted on an upper section of the radiator  4  is used as the air hole. 
     First, as shown in FIG. 1, to discharge the cooling water to change it to new one, the temperature of the cooling water is adequately reduced after stopping the engine. With the state, while adjusting an internal pressure of the cooling water re-circulation passage  1  due to open/close of the radiator cap  6 , the radiator cap  6  is opened to introduce air to the cooling water re-circulation passage  1 . The drain cock  5  is then opened to discharge the cooling water. The drain bolt  3  acting as the air hole close to the engine is opened and the cooling water close to the engine is conveyed toward the radiator to discharge it to outside through the drain cock  5 . 
     Next, to supply the cooling water to the passage  1 , the required amount of the cooling water is supplied to the passage  1  through the radiator cap  6  after the drain cock  5  is closed. When the cooling water is supplied, the drain bolt  3  acts as an air hole discharging smoothly air in the cooling water re-circulation passage  1  to outside. 
     With the conventional structure, it is possible to smoothly discharge the cooling water, which is close to the radiator  4 , of the cooling water re-circulation passage  1  due to the radiator cap  6 . It is further possible to smoothly discharge the cooling water, which is close to the engine having a complex structure, due to the drain bolt  3  arranged at a position higher than the engine side. 
     However, since the drain bolt  3  is arranged independently at the conventional cooling water re-circulation passage  1 , the conventional water-cooled exhaust gas re-circulation device has a complex layout to produce a redundant space and parts. 
     The invention was made to solve the foregoing problems. An object of the invention is to provide a water-cooled exhaust gas re-circulation device allowing simplifying the layout of the cooling water re-circulation passage and reducing costs due to reducing a component count and saving a space. 
     DISCLOSURE OF THE INVENTION 
     A water-cooled exhaust gas re-circulation device according to the invention is characterized in that a hole open/close mechanism allowing communication with outside air is arranged at a cooling water re-circulation passage cooling an exhaust gas re-circulation valve. In this way, since the cooling water re-circulation passage is integrated with the hole-open/close mechanism, it is possible to remove the drain bolt arranged independently of the exhaust gas re-circulation valve. It is possible to allow saving space, simplifying the structure and reducing a component count. 
     With the above arrangement, the water-cooled exhaust gas re-circulation device is characterized in that the hole-open/close mechanism is a drain bolt. In this way, even if an interference substance is close to the drain bolt, it is possible to ensure an air hole with respect to the cooling water re-circulation passage without removing the drain bolt. 
     With the above arrangement, the water-cooled exhaust gas re-circulation device is characterized in that the hole-open/close mechanism is arranged at a stopper stopping up a hole formed during manufacturing the cooling water re-circulation passage. In this way, it is not necessary to form an exclusive hole at the cooling water re-circulation passage in order to install the hole-open/close mechanism. It is possible to allow reducing costs and saving a space as compared with a case of forming the exclusive hole. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 illustrates a schematic representation of the whole of a conventional cooling water re-circulation passage arranged at the internal combustion engine. 
     FIG. 2 is a front view of a water-cooled exhaust gas re-circulation device arranged at the conventional cooling water re-circulation of FIG. 
     FIG. 3 is a cross sectional view taken along lines III—III of FIG.  2 . 
     FIG. 4 is a cross sectional view of a hole formed at a part of the cooling water re-circulation passage within the water-cooled exhaust gas re-circulation device during a die casting. 
     FIG. 5 is a front view of a water-cooled exhaust gas re-circulation device as embodiment 1 according to the invention. 
     FIG. 6 is a plan view of the water-cooled exhaust gas re-circulation device of FIG.  5 . 
     FIG. 7 is a side view of the water-cooled exhaust gas re-circulation device of FIG.  5 . 
     FIG. 8 is a cross sectional view taken along lines VIII—VIII of FIG.  5 . 
     FIG. 9A is an enlarged plan view of a drain bolt of FIG.  8 . 
     FIG. 9B is a plan view of a state of loosening the drain bolt of FIG. 9A inserted in a hole. 
     FIG. 10 illustrates a schematic representation of the whole of a cooling water re-circulation passage arranged at the internal combustion engine provided with the water-cooled exhaust gas re-circulation device as embodiment 1 according to the invention. 
    
    
     BEST MODES FOR CARRYING OUT THE INVENTION 
     To explain the invention more in detail, the best modes of carrying out the invention will be described with reference to the accompanying drawings. 
     EMBODIMENT 1 
     FIG. 5 is a front view of a water-cooled exhaust gas re-circulation device as embodiment 1 according to the invention. FIG. 6 is a plan view of the water-cooled exhaust gas re-circulation device of FIG.  5 . FIG. 7 is a side view of the water-cooled exhaust gas re-circulation device of FIG.  5 . FIG. 8 is a cross sectional view taken along lines VIII—VIII of FIG.  5 . FIG. 9A is an enlarged plan view of a drain bolt of FIG.  8 . FIG. 9B is a plan view of a state of loosening the drain bolt of FIG. 9A inserted in a hole. FIG. 10 illustrates a schematic representation of the whole of a cooling water re-circulation passage arranged at the internal combustion engine provided with the water-cooled exhaust gas re-circulation device as embodiment 1 according to the invention. Components of the embodiment 1 common to the conventional components are denoted by the same reference numerals and further description will be omitted. 
     In these drawings, a reference numeral  20  denotes a drain bolt, which is inserted rotationally into the hole  17 , which is formed at the cooling water re-circulation passage  1  in a manufacturing step such as die casting and so on, through a packing  21 . The drain bolt  20  includes a head section  20   a  having a major diameter, a leg section  20   b  having an outer diameter corresponding to an inner diameter of the hole  17 , a threaded section  20   c  formed at an outer peripheral face of the leg section  20   b , and a pair of notches  20   d  formed at a lower section of the leg section  20   b  in a chord or lateral direction as shown in FIG.  9 A and FIG.  9 B. 
     Next, an operation will be explained. 
     First, as shown in FIG. 10, to discharge the cooling water to change it to new one, the temperature of the cooling water is adequately reduced after stopping the engine. With the state, while adjusting an internal pressure of the cooling water re-circulation passage  1  due to open/close of the radiator cap  6 , the radiator cap  6  is opened to introduce air to the cooling water re-circulation passage  1 . The drain cock  5  is then opened to discharge the cooling water. The drain bolt  20 , which acts as the air hole close to the engine and is integrated with the water-cooled exhaust gas device, is rotated to loosen it. In this way, air is introduced to the cooling water re-circulation passage  1  through a gap defined between the notches  20   d  of the drain bolt  20  and an inner peripheral wall of the hole  17 . The cooling water close to the engine is then conveyed toward the radiator to discharge it to outside through the drain cock  5 . 
     Next, to supply the cooling water to the passage  1 , the required amount of the cooling water is supplied to the passage  1  through the radiator cap  6  after the drain cock  5  is closed. When the cooling water is supplied, the drain bolt  20  being integrated with the water-cooled exhaust gas re-circulation device is loosened. In this way, the drain bolt  20  acts as an air hole discharging smoothly air in the cooling water re-circulation passage  1  to outside. Thus, the air communication through the drain bolt  20  can be performed only by opening and closing the drain bolt  20 . Even if an interference substance X is close to the drain bolt  20  as shown in FIG. 9B, it is possible to supply air to the cooling water re-circulation passage  1  or to discharge air therefrom through a slight space close to the head section  20   a  of the drain bolt  20  using the drain bolt  20  without removing it. 
     As described above, according to the embodiment 1, the drain bolt  20  acting as the hole-open/close mechanism is integrated with the cooling water re-circulation passage  1  to result in removing the conventional drain bolt  3  independent of the exhaust gas re-circulation valve. In this way, it is possible to allow saving space, simplifying the structure and reducing a component count. 
     With the embodiment 1, even if the interference substance X is close to the drain bolt  20 , it is possible to ensure an air hole with respect to the cooling water re-circulation passage  1  without removing the drain bolt  20 . 
     With the embodiment 1, the drain bolt  20  acting as the hole-open/close mechanism is arranged in the hole  17  formed at the cooling water re-circulation passage  1  due to the die casting. In this way, it is not necessary to form an exclusive hole, at the cooling water re-circulation passage  1  in order to install the hole-open/close mechanism. It is possible to allow reducing costs and saving a space as compared with a case of forming the exclusive hole. 
     Moreover, with the embodiment, the drain bolt  20  acting as the hole-open/close mechanism is arranged in the hole  17  formed at the cooling water re-circulation passage  1  due to the die casting. Alternatively, the drain bolt  20  may be arranged at the cooling water re-circulation passage  1  other than the hole  17  to allow communicating with outside. With the embodiment 1, the drain bolt  20  is used as the hole-open/close mechanism. Alternatively, the invention is not limited to this embodiment. 
     INDUSTRIAL APPLICABILITY 
     As apparent from the foregoing, with the water-cooled exhaust gas re-circulation device according to the invention, the drain bolt acting as the hole-open/close mechanism is integrated with the cooling water re-circulation passage to result in removing the conventional drain bolt independent of the exhaust gas re-circulation valve. In this way, it is possible to allow saving a space, simplifying the structure and reducing a component count.