Patent Publication Number: US-11377997-B2

Title: Cooling device for power source for boat propulsion apparatus

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims the benefit of priority of Japanese Patent Application No. 2019-063227, filed Mar. 28, 2019, the entire contents of which are incorporated herein by reference. 
     BACKGROUND OF THE INVENTION 
     Field of the Invention 
     The present invention relates to a cooling device for a power source for a boat propulsion apparatus that removes residual foreign substances in cooling water for cooling an engine or an electric motor by filtering the cooling water. 
     Description of the Related Art 
     In recent years, pollution by litter (especially microplastic) in the sea, lakes, or rivers has become a serious environmental destruction problem, and some sort of measures for collecting them are desired to be taken. Although the definition of microplastic is not yet fixed, it generally refers to fine plastic particles having a size of 5 mm or less. In general, the smaller the size of litter, the more difficult it is to collect. In particular, microplastics have a great influence on aquatic organisms, and therefore proactive collecting measures are desired to be taken. 
     To cool the engine or electric motor of the boat propulsion apparatus, generally, outside water is taken into the boat propulsion apparatus as cooling water to cool the heat generation part of the engine or electric motor, and the cooling water after cooling such part is then drained out of the propulsion apparatus. However, the water once taken is simply returned to the water as it is, and the purification point of view (environmental measures) has been overlooked for the cooling water. 
     A strainer or the like is generally provided at the cooling water intake in the boat propulsion apparatus (see, for example, JP S61-184198 A), and large litter (e.g., a lid of a plastic bottle) are hard to get in the cooling water passage in the boat propulsion apparatus. However, there is a high possibility that fine litter (e.g., litter of about 1 mm) passing through the strainer is sucked into the cooling water passage as it is. While there is a chance of collecting such litter from the water sucked in as the cooling water, the opportunity to capture microplastic, which is particularly difficult to collect, has been missed. 
     JP 2003-063497 A discloses an example in which a filter is provided in the cooling water passage. However, this filter is provided in order to remove pebbles and algae. In other words, the filter disclosed in JP 2003-063497 A is simply intended to remove foreign substances and is basically the same as the filter provided at the water intake disclosed in JP S61-184198 A. 
     In the boat propulsion apparatus with a displacement of over 4000 cc and an output of 300 ps, it is possible to flow 100 L (liter) per minute of cooling water, which is 6000 L (corresponding to 30 oil drums) per hour. In the conventional boat propulsion apparatus, as described above, such a large amount of cooling water is drained as it is without collecting litter such as microplastic. Further, when collecting litter in the cooling water, the measure that causes deterioration of the power performance of the boat propulsion apparatus or requires addition of a complicated configuration leads to a decrease in the commercial value of the boat propulsion apparatus and is not a realistic measure. 
     SUMMARY OF THE INVENTION 
     The present invention has been made in consideration of the above circumstances, and an object of the present invention is to provide a cooling device for a power source for a boat propulsion apparatus that can collect and effectively remove environmental pollutants such as microplastics existing in water during cruising of the boat. 
     A cooling device for a power source for a boat propulsion apparatus according to an embodiment of the present invention includes a cooling water passage. The cooling water passage includes a passage provided in the power source, in which an engine or an electric motor is used as the power source of the boat propulsion apparatus that propels a boat. Water from outside the boat is taken into the cooling water passage as cooling water to cool the power source, and the cooling water after cooling the power source is drained from the cooling water passage. From the cooling water flowing through the cooling water passage, foreign substances having a size that clogs the cooling water passage are removed. The cooling water passage is provided with a filter device which can filter residual foreign substances remaining in the cooling water. 
     According to the present invention, the cooling water passage including the passage provided in the power source of the boat propulsion apparatus is provided with the filter device that can filter the residual foreign substances remaining in the cooling water which flows through the cooling water passage to cool the power source. Hence, the environmental pollutants such as microplastics existing in water can be filtered, collected, and effectively removed by the filter device as the residual foreign substances remaining in the cooling water during cruising of the boat which is propelled by driving the power source. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The drawings show: 
         FIG. 1  illustrates a left side view of an outboard motor as a boat propulsion apparatus to which an embodiment of a cooling device of a power source for a boat propulsion apparatus according to the present invention is applied; 
         FIG. 2  is a perspective view showing an engine or the like as the power source mounted in the outboard motor shown in  FIG. 1 ; 
         FIG. 3  is a diagram viewing from the direction of an arrow III in  FIG. 2 ; 
         FIG. 4  illustrates a front view showing a display window of an operation panel provided at a position visible from the driver&#39;s seat of the boat shown in  FIG. 1 ; 
         FIG. 5A  is a perspective view showing an example of a filter device shown in  FIGS. 2 and 3 ; and 
         FIG. 5B  is a perspective view showing another example of a filter device shown in  FIGS. 2 and 3 . 
     
    
    
     DETAILED DESCRIPTION 
     Hereinafter, an embodiment for carrying out the present invention will be described based on the drawings. 
       FIG. 1  illustrates a left side view of an outboard motor as a boat propulsion apparatus to which an embodiment of a cooling device of a power source for a boat propulsion apparatus according to the present invention is applied. An outboard motor  10  shown in  FIG. 1  as the boat propulsion apparatus includes an engine cover  11 , a drive shaft housing  12  provided below the engine cover  11 , and a gear case  13  provided below the drive shaft housing  12 . The outboard motor  10  is attached to the transom  1 A of the boat  1  using a bracket device  14  disposed at the front of the outboard motor  10 . 
     The drive system of the outboard motor  10  includes an engine  15  that is an internal combustion engine, a drive shaft  16 , a propeller shaft  18 , and propulsion propellers  19 A and  19 B. The engine  15  is the power source of the outboard motor  10 , is mounted on an engine holder  20 , and is housed in the engine cover  11  together with the engine holder  20 . The engine  15  is a water-cooled engine and is arranged so that the axial direction of a crankshaft  21  is up and down. As shown in  FIG. 2 , in the engine  15  a crankcase  22 , a cylinder block  23 , a cylinder head  24 , and a head cover  25  are sequentially arranged from the front side to the rear side of the outboard motor. 
     The drive shaft  16  shown in  FIG. 1  is disposed in the drive shaft housing  12  so as to extend in the vertical direction, and the rotational power of the engine  15  is transmitted to the drive shaft  16 . The drive shaft  16  includes a first drive shaft  16 A and a second drive shaft  16 B. A shift mechanism (not shown) is arranged between the first drive shaft  16 A and the second drive shaft  16 B, and the shift mechanism performs connecting and disconnecting of the transmission of rotation power and performs switching of the rotation direction. 
     The propeller shaft  18  is disposed in the gear case  13  so as to extend in the front-rear direction, and transmits the rotational power of the engine  15  transmitted to the drive shaft  16  to the propulsion propellers  19 A and  19 B. The propulsion propellers  19 A and  19 B form a counter-rotating propeller. 
     The engine cover  11  includes an under cover  11 A and an upper cover  11 B that is detachably attached to the upper portion of the under cover  11 A. The under cover  11 A covers the lower part of the engine  15  and the engine holder  20 , and the upper cover  11 B covers the upper part of the engine  15 . The combustion air intakes  26  are opened on the left and right sides of the upper cover  11 B. 
     The engine  15  is water-cooled type as described above, and the outboard motor  10  is provided with a cooling water passage  30  including a water jacket (not shown) of the engine  15 . The cooling water passage  30  includes a supply side passage  30 A for supplying the cooling water to the water jacket of the engine  15  and a drain side passage  30 B for guiding the cooling water after cooling the engine  15 . 
     The most upstream side of the supply side passage  30 A is a water intake port  31  opened at the front end of the gear case  13 . The most downstream side of the drain side passage  30 B is a drain port  32  formed in the hub of the propulsion propeller  19 B. The supply side passage  30 A is formed inside the gear case  13 , the drive shaft housing  12 , and the engine holder  20 , and supplies water to the engine  15 . The drain side passage  30 B includes a drainage pipe  33  that connects the cylinder block  23  of the engine  15  and the engine holder  20 , and is formed inside the engine holder  20 , the drive shaft housing  12 , and the gear case  13 . 
     Water outside the boat  1  and the outboard motor  10  is taken into the supply side passage  30 A as the cooling water from the water intake port  31 . The cooling water flows through the supply side passage  30 A and reaches the water jacket of the engine  15  by the operation of a water pump (not shown) driven by the drive shaft  16 , and cools the combustion chamber and exhaust passage (both not shown) of the engine  15  and the like. The cooling water after cooling the engine  15  flows through the drain side passage  30 B including the drainage pipe  33  and is drained from the drain port  32  to the outside of the outboard motor  10 . 
     The water intake port  31  of the supply side passage  30 A is provided with a strainer  34  that captures foreign substances having a size that may cause clogging of the cooling water passage  30 , such as pebbles and algae. Alternatively, when the strainer  34  is not positioned in the water intake port  31 , the water intake port  31  itself is formed in the porous structure having many holes of small diameters. The cooling water flowing in the cooling water passage  30  is the cooling water from which foreign substances having a size that cause clogging of the cooling water passage  30  are removed by the strainer  34 . 
     Further, the cooling water passage  30  (supply side passage  30 A and drain side passage  30 B) is provided with a filter device  35  that can filter and collect residual foreign substances remaining in the cooling water flowing in the cooling water passage  30 , especially environmental pollutants such as microplastics. Here, the microplastics refers to fine plastic particles, generally having a size of 5 mm or less, diffused in an environment such as the ocean. In the present embodiment, the lower limit of the size of the remaining foreign substances captured and collected by the filter device  35  is close to the lower limit of the size visually observable with the naked eye, for example, about 0.1 to 0.2 mm. 
     As described above, the filter device  35  is disposed in the cooling water passage  30 , whereby the environmental pollutants such as microplastics existing in water can be captured and collected by the filter device  35  and hence effectively removed during the operation of the outboard motor  10  that drives the engine  15 , that is, during cruising of the boat  1 . 
     Further, a large amount of cooling water can flow through the outboard motor  10  having a large amount of drainage and a high output. For example, in the outboard motor  10  with a displacement of over 4000 cc and an output of 300 ps, it is possible to flow a cooling water of 100 L per minute, which is cooling water of 6000 L (corresponding to 30 oil drums) per hour. This makes it possible to remove a large amount of marine pollutants (such as microplastics) in the cooling water in one voyage. 
     In addition, by cruising around the fish cages with boat  1  provided with the outboard motor  10 , fish farmers who use the cages can effectively capture the rest of the baits and the like as well as the microplastics by the filter device  35  installed in the outboard motor  10 , and thus can proactively contribute to the prevention of marine pollution. 
     The filter device  35  described above may be provided in either the supply side passage  30 A or the drain side passage  30 B of the cooling water passage  30 . The present embodiment shows an example in which the filter device  35  is disposed in the drain side passage  30 B that guides the cooling water after cooling the engine  15  to the drain port  32 , particularly disposed in the middle of the drainage pipe  33 . As shown in  FIGS. 1 and 2 , the drainage pipe  33  is disposed on the side of the cylinder head  24  of the engine  15 , so that the filter device  35  disposed in the drainage pipe  33  is provided in the upper cover  11 B of the engine cover  11 . Accordingly, the filter device  35  is easily maintained by removing the upper cover  11 B from the under cover  11 A. 
     In addition, the filter device  35  is disposed in the middle of the drain side passage  30 B (drainage pipe  33 ) of the cooling water passage  30  to efficiently capture and collect residual foreign substances (environmental pollutants such as microplastics) in the cooling water. The cooling water flowing through the drain side passage  30 B is heated to a high temperature when the engine  15  is warmed up, and the viscosity is lower than that of the cooling water in the cold state before cooling the engine  15 . Thus, the cooling water containing residual foreign substances such as microplastics easily flows with low passage resistance in the filter device  35 , and the residual foreign substances can be efficiently captured by the filter device  35 . 
     Moreover, by filtering the cooling water in the drain side passage  30 B with the filter device  35 , it is possible to capture and collect the litter remaining in the engine  15 . Thus, environmental pollutants can be removed without affecting the power performance of the engine  15  by filtering the cooling water after cooling the engine  15  with the filter device  35 , and the commercial value of the outboard motor  10  can be increased. 
     The above-described filter device  35  is a detachable cartridge type filter device as shown in  FIGS. 5A and 5B . As shown in  FIG. 5A , the filter device  35  may be a basket type filter device in which the filter device  35  includes a lattice-shaped basket body  39  detachably attached to and accommodated in a container  38 . The container has an inflow pipe  36  and an outflow pipe  37  both connected to the drainage pipe  33 , and the opening of the container  38  is closed by a transparent lid  40  screwed to the container  38 . In this case, the basket body  39  captures residual foreign substances such as microplastics in the cooling water. When the basket body  39  is clogged with residual foreign substances, the basket body  39  is detached from the container  38  and the captured residual foreign substances are removed therefrom, and then the basket body  39  is reattached to the container  38 . 
     Alternatively, as shown in  FIG. 5B , the filter device  35  may be a cassette type filter device in which the filter device includes a capsule-like filter  42  detachably attached to a main body  41  and the filter  42  is covered with a transparent cap  43  that is screwed to the main body  41 . In this case, the filter  42  captures residual foreign substances such as microplastics in the cooling water. When the filter  42  is clogged with residual foreign substances, the filter  42  is replaced with a new one. Anyone can easily maintain the filter device  35  by using the cartridge type filter device  35  as described above. 
     As shown in  FIGS. 2 and 3 , the drainage pipe  33  of the drain side passage  30 B is connected to a bypass passage  45  for flowing cooling water to bypass the filter device  35  when the filter device  35  is clogged. A relief valve  44  is disposed at a connection portion between the upstream end of the bypass passage  45  and the drainage pipe  33 . 
     The relief valve  44  is closed when the filter device  35  is not clogged to guide the cooling water flowing through the drainage pipe  33  to the filter device  35 . The relief valve  44  opens when the filter device  35  is clogged to guide the cooling water flowing through the drainage pipe  33  to the bypass passage  45  so as to bypass the filter device  35 . Thereby, even when clogging occurs in the filter device  35  and the clogging is not eliminated, it is possible to prevent the cooling performance of the engine  15  from being deteriorated. 
     The occurrence of the above-mentioned clogging of the filter device  35  is detected by, for example, a pressure sensor installed near the upstream side of the filter device  35  in the drainage pipe  33 . On the basis of the detected value of the pressure sensor, the clogging of the filter device  35  is notified to the user of the outboard motor  10  in a recognizable manner by at least one of a warning display  47  (see  FIG. 4 ) and a warning display  48  (see  FIG. 1 ). The warning display  47  may be provided on a display window  46 A of the operation panel  46  provided at a position visible from the driver&#39;s seat of the boat  1 , and a warning display  48  may be provided on the upper cover  11 B of the outboard motor  10 . The clogging of the filter device  35  may be notified to the user of the outboard motor  10  in a recognizable manner by an alarm from a buzzer or voice or the like. 
     Further, in order to prevent overheating of the engine  15  due to clogging of the filter device  35 , it is also effective to notify the user of the outboard motor  10  of a temperature alarm of the engine  15 , although not shown. In  FIG. 4 , reference numeral  49  indicates a temperature display of the cooling water flowing through the engine  15 , reference numeral  50  indicates an engine speed display, reference numeral  51  indicates a boat propulsion speed display, and reference numeral  52  indicates a shift display which shows state of the outboard motor  10  such as forward or reverse. 
     The above-mentioned embodiments are presented as examples only, but not intended to limit the scope of the inventions. The embodiments described herein may be embodied in various forms, and furthermore, omissions, substitutions and changes of the present embodiments may be made without departing from the spirit of the inventions. The accompanying claims and their equivalents are intended to cover such modifications as would fall within the scope of the inventions. 
     For example, the outboard motor  10  may be driven by a water-cooled electric motor, and the filter device  35  may collect and remove residual foreign substances (environmental pollutants such as microplastics) in the cooling water for cooling the electric motor. In addition, the boat propulsion apparatus is not limited to the outboard motor  10  and includes any power source which propels the boat and requires cooling.