Abstract:
A lubrication device for an engine, includes: an oil pan which is disposed at a lower portion of an engine and stores lubrication oil; an oil pump which is disposed above the oil pan and driven by the engine; a suction oil passage which guides the oil in the oil pan to a suction port of the oil pump; and a supply oil passage which guides the oil discharged from a discharge port of the oil pump to lubrication parts of the engine. The suction oil passage is divided into an upstream oil passage on a side of the oil pan and a downstream oil passage on a side of the oil pump. A filter net serving as a strainer is sandwiched between the upstream oil passage and the downstream oil passage. Thus, it is possible to provide the light and simply-structured lubrication device for an engine.

Description:
RELATED APPLICATION DATA  
       [0001]     The present invention is based upon Japanese priority application Nos. 2006-269346 and 2006-269347, which are hereby incorporated in their entirety herein by reference.  
       BACKGROUND OF THE INVENTION  
       [0002]     1. Field of the Invention  
         [0003]     The present invention relates to an improvement of a lubrication device for an engine and an outboard engine system, comprising: an oil pan which is disposed at a lower portion of an engine and stores lubrication oil; an oil pump which is disposed above the oil pan and driven by the engine; a suction oil passage which guides the oil in the oil pan to a suction port of the oil pump; a supply oil passage which guides the oil discharged from a discharge port of the oil pump to lubrication parts of the engine; and a strainer which filters the oil sucked from the oil pan by the oil pump.  
         [0004]     2. Description of the Related Art  
         [0005]     Such a lubrication device for an engine is known as disclosed in Japanese Patent Application Laid-open No. 7-305617 and Japanese Patent Application Laid-open No. 58-183384.  
         [0006]     In the conventional lubrication device for an engine, a strainer is mounted to a lower end of a suction pipe disposed in an oil pan. In this device, because the strainer comprises a strainer case directly connected to an opening at the lower end of the suction pipe, and a filter net provided so as to extend in the strainer case, the strainer is heavy and easily swings along with the suction pipe with its own inertia force. Thus, in order to prevent the swing, the suction pipe is supported by a stay extending from an inner wall of the oil pan. In this way, the conventional device has a large weight and a complicated structure.  
         [0007]     Further, in the conventional lubrication device for an engine and an outboard engine system, a cooling water passage of the engine is disposed in a central portion of the oil pan so as to pass through the oil pan so that cooling water cools the oil stored in the oil pan. However, in order to cool the entire oil stored in the oil pan with the cooling water of the engine, a large amount of cooling water is required, leading to an extremely low cooling efficiency.  
       SUMMARY OF THE INVENTION  
       [0008]     The present invention has been achieved in view of the above-described circumstances. The present invention has a first object to provide a light and simply-structured lubrication device for an engine. Also, the present invention has a second object to provide a lubrication device for an engine and an outboard engine system in which a suction oil passage for guiding oil in an oil pan to a suction port of an oil pump is cooled with cooling water of the engine, thereby efficiently cooling the oil to be supplied to lubrication parts of the engine.  
         [0009]     In order to achieve the first object, according to a first feature of the present invention, there is provided a lubrication device for an engine, comprising: an oil pan which is disposed at a lower portion of an engine and stores lubrication oil; an oil pump which is disposed above the oil pan and driven by the engine; a suction oil passage which guides the oil in the oil pan to a suction port of the oil pump; a supply oil passage which guides the oil discharged from a discharge port of the oil pump to lubrication parts of the engine; and a strainer which filters the oil sucked from the oil pan by the oil pump, wherein the suction oil passage is divided into an upstream oil passage on a side of the oil pan and a downstream oil passage on a side of the oil pump, and a filter net serving as the strainer is sandwiched between the upstream oil passage and the downstream oil passage.  
         [0010]     With the first feature of the present invention, the filter net which exerts a strainer function is sandwiched between the upstream oil passage and the downstream oil passage of the suction oil passage. Therefore, a strainer case is not required unlike the case of the conventional device, thereby contributing to reduction in weight of the lubrication device.  
         [0011]     According to a second feature of the present invention, in addition to the first feature, the upstream oil passage is integrally formed in a sidewall of the oil pan.  
         [0012]     With the second feature of the present invention, the upstream oil passage of the suction oil passage is integrally formed in the sidewall of the oil pan. Therefore, a stay is not required for supporting the suction pipe unlike the case of the conventional device, thereby further contributing to reduction in weight of the lubrication device.  
         [0013]     According to a third feature of the present invention, in addition to the second feature, the downstream oil passage is provided in a case member which is joined to an upper end surface of the oil pan via a gasket so as to support the oil pan, and the filter net is connected to the gasket. The case member corresponds to a mount case  16  in an embodiment of the present invention which will be described later.  
         [0014]     With the third feature of the present invention, the filter net is integrally connected to the gasket interposed between the joint surfaces of the case member and the oil pan. Therefore, the support structure of the filter net is simplified and becomes reliable, thereby contributing to reduction in cost of the lubrication device.  
         [0015]     In order to achieve the second object, according to a fourth feature of the present invention, there is provided a lubrication device for an engine, comprising: an oil pan which is disposed at a lower portion of an engine and stores lubrication oil; an oil pump which is disposed above the oil pan and driven by the engine; a suction oil passage which guides the oil in the oil pan to a suction port of the oil pump; and a supply oil passage which guides oil discharged from a discharge port of the oil pump to lubrication parts of the engine, wherein at least a part of a cooling water passage for guiding cooling water supplied to the engine is disposed adjacent to at least a part of the suction oil passage via a common partition wall. The part of the cooling water passage corresponds to a cooling chamber inlet chamber  26  in the embodiment of the present invention which will be described later.  
         [0016]     With the fourth feature of the present invention, the oil with a limited flow rate which flows out of the oil pan and sucked by the oil pump is cooled by the cooling water flowing through the cooling water passage, thereby improving the oil cooling efficiency. Further, the thus-cooled oil performs cooling of the engine as well as lubrication of the engine, thereby contributing to improvement of the durability of the engine.  
         [0017]     According to a fifth feature of the present invention, in addition to the fourth feature, at least an upstream oil passage of the suction oil passage is formed in one sidewall of the oil pan, and at least the part of the cooling water passage is integrally connected to the oil pan so that the part of the cooling water passage is adjacent to the upstream oil passage via the common partition wall.  
         [0018]     With the fifth feature of the present invention, at least the upstream oil passage of the suction oil passage is formed in one sidewall of the oil pan, and at least a part of the cooling water passage is integrally connected to the oil pan so that the part of the cooling water passage is adjacent to the upstream oil passage via the common partition wall. Therefore, it is not required to dispose pipes of the upstream oil passage and the part of the water passage, or a stay for supporting them, thereby simplifying the lubrication device for the engine and reducing its weight. Further, heat transmission from the upstream oil passage to the cooling water passage becomes excellent, thereby effectively cooling the oil flowing to the oil pump.  
         [0019]     In order to achieve the second object, according to a sixth feature of the present invention, there is provided a lubrication device for an outboard engine system including a casing which supports a propeller shaft at a lower portion thereof and an engine which is mounted at an upper portion of the casing and has a vertically-arranged crankshaft, the lubrication device comprising: an oil pan which is formed in the casing and stores lubrication oil to be supplied to the engine; an oil pump driven by the engine; a suction oil passage which guides the oil in the oil pan to a suction port of the oil pump; and a supply oil passage which guides oil discharged from a discharge port of the oil pump to lubrication parts of the engine, wherein at least an upstream oil passage of the suction oil passage is formed in one sidewall of the oil pan, and wherein at least a part of a cooling water passage is integrally connected to the oil pan so that the part of the cooling water passage is adjacent to the upstream oil passage via a common partition wall, the cooling water passage guiding cooling water which is taken in from a water intake port in the lower portion of the casing and which is supplied to the engine. The part of the cooling water passage corresponds to the cooling chamber inlet chamber  26  in the embodiment of the present invention which will be described later.  
         [0020]     With the sixth feature of the present invention, not only the oil pan but also the upstream oil passage, at least the part of the cooling water passage, and the common partition wall are formed in the casing. Therefore, it is not required to dispose pipes of the upstream oil passage and a part of the water passage, or a stay for supporting them, thereby simplifying the lubrication device for the engine and reducing its weight. Further, the cooing of the oil can be further facilitated by heat dissipation from the oil pan and the upstream oil passage to the casing.  
         [0021]     The above and other objects, features and advantages of the invention will become apparent from a preferred embodiment taken in conjunction with the accompanying drawings. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0022]      FIG. 1  is side view of an outboard engine system which includes a lubrication device according to an embodiment of the present invention.  
         [0023]      FIG. 2  is a partially enlarged sectional view of  FIG. 1 .  
         [0024]      FIG. 3  is a sectional view taken along line  3 - 3  in  FIG. 2 .  
         [0025]      FIG. 4  is a sectional view taken along line  4 - 4  in  FIG. 3 .  
         [0026]      FIG. 5  is a plane view of a gasket.  
         [0027]      FIG. 6  is an enlarged view of a part  6  in  FIG. 2 .  
         [0028]      FIG. 7  is a channel diagram of the lubrication device for an engine. 
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0029]     Referring to  FIG. 1 , in an outboard engine system O, a side on a stern bracket  8  is referred to as a front side, and a side opposite thereto is referred to as a rear side. The outboard engine system O includes a casing  1  which has a water-cooled multi-cylinder four-stroke engine E mounted in its upper portion, and supports a propeller shaft  3  at its lower portion. The propeller shaft  3  has a propeller  2  provided at its rear end. A vertically-extending swivel shaft  6  is mounted to the casing  1  via an upper arm  4  and a lower arm  5  so as to situate in front of the casing  1 . The swivel shaft  6  is rotatably supported by a swivel case  7  which is coupled to the stern bracket  8  via a horizontally-extending tilt shaft  9 . The stern bracket  8  is cramped to a transom Bt of a body of a ship. Therefore, the casing  1  is horizontally rotatable around the swivel shaft  6 , and vertically tiltable around the tilt shaft  9 .  
         [0030]     An engine hood  10  is detachably mounted at an upper end of the casing  1  so as to cover the engine E. An air intake port  11  is provided at a rear end of an upper portion of the engine hood  10 . An air intake chamber  12  and a throttle body  13  are disposed in a front portion in the engine hood  10 .  
         [0031]     The casing  1  includes an extension case  15 , a mount case  16  bolt-coupled to an upper end of the extension case  15 , and a gear case  17  bolt-coupled to a lower end of the extension case  15 . The extension case  15  includes an upper case  15   a  and a lower case  15   b  bolt-coupled to the upper case  15   a . The mount case  16  is bolt-coupled to an upper end surface of the upper case  15   a  with a gasket held therebetween. The engine E is mounted to the mount case  16  with a crankshaft  20  being vertically arranged and a cylinder block  14  facing rearward. An output shaft  21  connected to the crankshaft  20  is vertically arranged in the extension case  15 . A ring gear  22  is secured to a lower end of the crankshaft  20  so as to be driven by a starter device (not shown).  
         [0032]     The gear case  17  horizontally supports the propeller shaft  3  having the propeller  2  at its rear end, and houses a forward-reverse shifting gear mechanism  23  connecting the propeller shaft  3  to the output shaft  21 .  
         [0033]     In operation of the engine E, the power thereof is transmitted from the crankshaft  20  to the output shaft  21 , and further to the propeller shaft  3  via the forward-reverse shifting gear mechanism  23 , thereby driving the propeller  2 . The rotational direction of the propeller  2  is controlled and switched by the forward-reverse shifting gear mechanism  23 .  
         [0034]     Referring to  FIGS. 2 and 3 , integrally formed in the upper case  15   a  of the extension case  15  are an oil pan  25  occupying the front half portion or more of the upper case  15   a , and a cooling water outlet chamber  27  adjacent to one half of the rear portion of the oil pan  25 , and an idle exhaust chamber  50  adjacent to the other half of the rear portion of the oil pan  25 . A cooling chamber inlet chamber  26  is integrally formed in a central portion of the upper case  15   a  so as to be interposed between the oil pan  25  and the cooling water outlet chamber  27 . An exhaust passage  28  is integrally formed in a central portion of the cooling water inlet chamber  26  so as to vertically pass through the cooling water inlet chamber  26 . The idle exhaust chamber  50  is divided into a first chamber  50   a  on a radially inner side, and a second chamber  50   b  on a side outward of the first chamber  50   a . The chambers  50   a  and  50   b  communicate with each other through a communication hole  54  provided in their lower portions. The first chamber  50   a  communicates with an intermediate portion of the exhaust passage  28  through a passage (not shown). The second chamber  50   b  communicates with an idle exhaust pipe  56  which is mounted to a rear end of the mount case  16 . Thus, even when the lower end of the exhaust passage  28  is submerged in the water during idling of the engine E, the exhaust gas of the engine E flows from the intermediate portion of the exhaust passage  28  through the idle exhaust chamber  50  to be smoothly discharged through the idle exhaust pipe  56 .  
         [0035]     Now, the lubrication device for the engine E including the oil pan  25  will be described with reference to FIGS.  2  to  7 .  
         [0036]     As shown in  FIG. 2 , a valve operating camshaft  30  driven at a reduction ratio of ½ by the crankshaft  20  via a timing transmission device  29  is supported in a cylinder head  19  which is joined to a rear end of a cylinder block  14  such that the valve moving camshaft  30  is parallel with the crankshaft  20 . An oil pump  31  driven by the camshaft  30  is mounted to a lower end of the cylinder head  19 . A suction oil passage  33  is provided between an intake port of the oil pump  31  and the oil pan  25  so as to guide oil  32  in the oil pan  25  to the oil pump  31 .  
         [0037]     The suction oil passage  33  comprises an upstream oil passage  33   a  and a downstream oil passage  33   b  divided at the joint surfaces between the oil pan  25  and the mount case  16 . A stainless filter net  34  serving as a strainer is sandwiched between opposing portions of the upstream oil passage  33   a  and the downstream oil passage  33   b.    
         [0038]     The upstream oil passage  33   a  of the suction oil passage  33  is integrally formed in one sidewall of the oil pan  25 . An upstream end  37  of the upstream oil passage  33   a  is opened to a bottom portion in the oil pan  25  by boring with a rotary tool  36  which is inserted diagonally into an opening in an upper open surface of the oil pan  25 . This procedure eliminates the need of providing a closing plug after machining the upstream end  37 .  
         [0039]     The downstream oil passage  33   b  is integrally formed to extend from the mount case  16  through the cylinder block  14  to the cylinder head  19  to reach the intake port of the oil pump  31 .  
         [0040]     Referring to  FIGS. 2, 5  and  6 , the gasket  18  interposed between the joint surfaces of the upper case  15   a  and the mount case  16  is made of stainless steel, and extends to a position between the joint surfaces of the oil pan  25  and the mount case  16 . An opening  35  is provided in the gasket  18  at a portion corresponding to the suction oil passage  33 . The filter net  34  comprises a bulged portion  34   a  which is received in a portion extending from an upper end surface of the oil pan  25  to the upstream oil passage  33   a , and a joint flange  34   b  which radially protrudes from an upper end of the bulged portion  34   a . The joint flange  34   b  is welded to the periphery of the opening  35  of the gasket  18 . The filter net  34  is integrally connected to the gasket  18 .  
         [0041]     As shown in  FIG. 7 , a supply oil passage  38  is connected to a discharge port of the oil pump  31 . The supply oil passage  38  supplies the oil  32  to a first lubrication part  39  around the crankshaft  20  of the engine E, a second lubrication part  40  around the camshaft  30 , and a third lubrication part  41  around the timing transmission device  29 . An oil filter  43  and a relief valve  44  are provided on an upstream side of the supply oil passage  38 .  
         [0042]     Thus, during the operation of the engine E, the oil pump  31  driven by the camshaft  30  sucks the oil  32  in the oil pan  25  through the suction oil passage  33 , and discharges the oil  32  into the supply oil passage  38 , thereby supplying the oil  32  to the first to third lubrication parts  39  to  41  to lubricate the crankshaft  20 , the camshaft  30 , the timing transmission device  29  and the other components. The oil having completed lubrication of them is returned by the gravity to the oil pan  25 .  
         [0043]     In this process, the oil  32  flowing to the oil pump  31  is filtered by the filter net  34  in the suction oil passage  33 , and the oil  32  flowing to the first to the third lubrication parts  39  to  41  is further filtered by the oil filter  43  in the supply oil passage  38 .  
         [0044]     The filter net  34  which exerts the strainer function is sandwiched between the upstream oil passage  33   a  and the downstream oil passage  33   b , and thus it is not require to dispose a strainer case unlike the case of the conventional strainer, thereby contributing to reduction in weight of the lubrication device.  
         [0045]     Particularly because the filter net  34  is integrally connected to the gasket  18  interposed between the oil pan  25  and the mount case  16 , the support structure of the filter net  34  is simplified and becomes reliable, thereby contributing to reduction in cost of the lubrication device.  
         [0046]     The upstream oil passage  33   a  of the suction oil passage is integrally formed in the sidewall of the oil pan  25 , and thus it is not require to dispose a stay for supporting the suction pipe unlike the case of the conventional device, thereby further contributing to the reduction in weight of the lubrication device.  
         [0047]     Next, a cooling device of the engine E including the cooling water inlet chamber  26  and the cooling water outlet chamber  27  will be described with reference to FIGS.  1  to  4 .  
         [0048]     In  FIG. 1 , a water intake port  51  for taking in external water as cooling water is provided in one sidewall of the gear case  17 . On the other hand, as shown in  FIG. 2 , a bottom wall of the cooling water inlet chamber  26  is conical, and a connection port  26   a  is provided in its lowermost portion. A water suction tube  52  is disposed in the extension case  15  so as to connect the water intake port  51  and the connection port  26   a  to each other. A water pump  53  driven by the output shaft  21  is provided at an intermediate portion of the water suction tube  52  so as to pressurizingly feed the water taken in from the water intake port  51  into the cooling water inlet chamber  26 .  
         [0049]     The cooling water inlet chamber  26  communicates with the inlet port of a water jacket (not shown) of the engine E so as to guide the cooling water pressurizingly fed from the water pump  53  to the water jacket. The cooling water having completed the cooling the engine E while passing through the water jacket moves into the cooling water outlet chamber  27 . The cooling water having moved into the cooing water outlet chamber  27  is released into the extension case  15  through a drainage hole  27   a  in the bottom wall of the cooling water outlet chamber  27 .  
         [0050]     A downstream end of the exhaust passage  28  passing through the central portion of the cooling water inlet chamber  26  is also opened into the extension case  15 , and thus the cooling water is discharged to the outside through a through-hole provided in the central portion of the propeller  2 , together with the exhaust gas discharged from the exhaust passage  28 .  
         [0051]     If the connection port  26   a  is disposed on the front side in the bottom portion of the cooling water inlet chamber  26 , the residual water in the cooling water inlet chamber  26  is more reliably discharged into the connection port  26   a  when the outboard engine system O is brought into a forward tilt-up state after stopping the operation of the engine E.  
         [0052]     The cooling water inlet chamber  26 , the oil pan  25  and the upstream oil passage  33   a  of the suction oil passage  33  are integrally formed in the upper case  15   a  of the extension case  15 . The cooling water inlet chamber  26  and the upstream oil passage  33   a  are disposed to be adjacent to each other with a common partition wall  16   a  integral with the upper case  15   a  therebetween.  
         [0053]     Thus, the cooling water in the cooling water inlet chamber  26  cools the oil with a limited flow rate which flows out of the oil pan  25  and sucked by the oil pump  31 , thereby improving the oil cooling efficiency. Further, the thus-cooled oil performs cooling of the first to the third lubrication parts  39  to  41  of the engine as well as lubrication thereof, thereby contributing to improvement of the durability of the engine E.  
         [0054]     In this device, the oil pan  25 , the upstream oil passage  33   a  of the suction oil passage  33 , the cooling water inlet chamber  26 , and the common partition wall  55  between the upstream oil passage  33   a  and the cooling water inlet chamber  26  are integrally formed in the upper case  15   a  of the extension case  15 . Therefore, it is not required to dispose pipes of the upstream oil passage  33   a  and the part of the water passage, or a stay for supporting them, thereby simplifying the lubrication device and reducing its weight, and thus simplifying the outboard engine system O and reducing its weight. Further, the heat dissipation from the oil pan  25  and the upstream oil passage  33   a  to the extension case  15  becomes excellent, thereby further facilitating the cooling of the oil.  
         [0055]     The embodiment of the present invention has been described above, but various changes in design may be made without departing from the subject matter of the present invention.