Patent Publication Number: US-2009235894-A1

Title: Lubrication apparatus for engines

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a lubrication apparatus for an engine, and more particularly, to a lubrication apparatus adapted to be used in a four-stroke internal combustion engine, where appropriate lubrication can be applied to the engine no matter the engine is situated at any state of declination. 
     2. Description of Related Art 
     A comparison between a four-stroke engine and a two-stroke engine shows that the former prevails over the latter in terms of cleaner exhaust and fuel saving. Under strict environmental regulations, compact-sized apparatuses for agricultural usage or compact-sized power devices for leisure usage have been changed into four-stroke engines, such as mowers, sawing machines, and so forth. In the above-mentioned applications, since apparatuses are likely to be operated at any directions, engines are required to be maneuvered at various angles of declination. This indicates that engine lubrication systems have to satisfy such demands that lubrication needs to accurately apply to engine components when engines are operated at various angles of declination. 
     Currently, hand-held four-stroke engines are, mostly, lubricated in such a manner that lubricant in an oil pan is first agitated by rotation of a fork, and then the lubricant is sucked into a crankcase for lubricating components such as a crankshaft, pistons and so forth. Nevertheless, such an agitating-lubricating manner not only causes power loss and reduces power output of the engine; but also causes lubricant-level changed when engines are declined such that quantity of the lubricant to be agitated becomes less and less. As a result, lubrication becomes insufficient and fails to achieve the purpose of lubrication. 
     Taiwan Patent No. I242622 discloses a lubrication apparatus for a four-stroke engine, comprising a crankshaft chamber independently formed in a cylinder block of the engine, a camshaft chamber, and an oil reservoir chamber, incorporated additionally with an oil distributing chamber in communication with the above chambers. The oil reservoir chamber stores lubricants, and there is arranged with an oil-suction piping path, together with a plurality of oil-suction orifices provided on wall of the oil-suction piping path, and an air-suction vent is provided at an end of the piping path. Therefore, upon rising of a piston where a negative-pressure status is effected in the crankshaft chamber, communication between the crankshaft chamber and the oil-suction pipe in the oil reservoir chamber is achieved through the oil distributing chamber, such that the air being sucked can flow rapidly in the oil-suction piping path. As such, a pressure difference so effected will atomize the lubricant sucked through the oil-suction orifices, and eventually the lubricant flows into the crankshaft chamber. During a descending stroke of the piston, the oil distributing chamber builds communication between the crankshaft chamber and the camshaft chamber, so that the atomized lubricant is distributed to the camshaft chamber for lubricating engine components. 
     As mentioned above, it is undesirable for the conventional lubrication apparatus because design in the oil distributing chamber is complicated. Besides, after review and simulation, the quantity of lubricant supplied by the negative-pressure effect for lubricating the engine is found, in the overall circulation cycle, much more than what is actually required. 
     SUMMARY OF THE INVENTION 
     The object of the present invention is to provide a lubrication apparatus for an engine, comprising a crankshaft chamber, a camshaft chamber, and an oil reservoir chamber. The crankshaft chamber is in communication with a space underneath a piston, and includes a crankshaft chamber inlet and a crankshaft chamber outlet. The oil reservoir chamber is provided for storing lubricants. 
     An oil-suction piping path is provided in the oil reservoir chamber, and is communicated between the crankshaft chamber inlet and the oil reservoir chamber. A first one-way valve is arranged between the crankshaft chamber and the oil reservoir chamber, where a valve inlet and a valve outlet are communicated, respectively, with the crankshaft chamber outlet and the oil reservoir chamber. The oil-suction piping path includes, among others, a rotatable pipe which is pivotally arranged along an axis of a cylinder block. The rotatable pipe includes a plurality of oil-suction orifices located at wall of the rotatable pipe and an air-suction vent at an end of the rotatable pipe. No matter the engine is situated any state of declination, the air-suction vent is kept above a surface of the lubricant, and that at least one of the oil-suction orifices is kept under the surface of the lubricant. 
     With the help of the oil-suction piping path and of the first one-way valve, the lubrication apparatus for an engine according to the present invention can supply an appropriate amount of lubricant to corresponding chambers either at a rising stroke or at a descending stoke of the piston. Besides, even under various declination states, a four-stroke engine can be appropriately lubricated, namely, unlike the conventional fork-supply manner which has an un-predetermined quantity of lubricant, or the prior art supply manner which has an over-supply of lubricant. 
     A crankshaft chamber may be defined by an upper crankcase and a lower crankcase which are anchored to each other. The oil-suction piping path may further include, in sequence, an oil-pan built-in passage, a connecting pipe, and a lower-crankcase built-in passage. The oil-pan built-in passage is connected with the rotatable pipe, and that the lower-crankcase built-in passage with the crankshaft chamber inlet. The rotatable pipe may include a C-shaped tube. 
     In one embodiment, according to the present invention, the lubrication apparatus for an engine may further include a rocker arm chamber which, through a first communicating passage, is communicated with the crankshaft chamber. In the first communicating passage there is provided with a second one-way valve, where an inlet and an outlet of the second one-way valve are in communication with the rocker arm chamber and the camshaft chamber, respectively. The camshaft chamber can, through a second communicating passage, be communicated with the oil reservoir chamber. 
     Further, in another embodiment, the camshaft chamber can, through two communicating passages, be communicated with the oil reservoir chamber and the crankshaft chamber, respectively. In one of the two communicating passages there is arranged with a one-way relief valve for pressure release, wherein a valve inlet and a valve outlet of the one-way relief valve are communicated with the oil reservoir chamber and the camshaft chamber, respectively. The two communicating passages may be two piping paths independent from each other, or both have a common path section. In this embodiment, the lubrication apparatus for an engine may further include a rocker arm chamber. A second one-way valve is arranged between the rocker arm chamber and the crankshaft chamber, such that the rocker arm chamber and the crankshaft chamber are in a one-way communication, and that a valve inlet and a valve outlet of the second one-way valve are communicated with the rocker arm chamber and the crankshaft chamber, respectively. 
     Other objects, advantages, and novel features of the present invention will become more apparent from the following detailed description when taken in conjunction with the accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is an exploded view illustrating a lubrication apparatus for an engine according to a first embodiment of the present invention; 
         FIG. 2  is a cross-sectional view illustrating the lubrication apparatus for an engine according to the first embodiment of the present invention; 
         FIG. 3  is a cross-sectional view illustrating a rotatable pipe according to the first embodiment of the present invention; 
         FIG. 4  is a cross-sectional view illustrating recycle of lubricant in a rocker arm chamber, as viewed from one angle, according to the first embodiment of the present invention; 
         FIG. 5  is a cross-sectional view illustrating a lubricant applied in the camshaft chamber/rocker arm chamber according to the first embodiment of present invention; 
         FIG. 6  is a cross-sectional view illustrating recycle of lubricant in the rocker arm chamber, as viewed from another angle, according to the first embodiment of the present invention; 
         FIG. 7  is a cross-sectional view illustrating recycle of lubricant in the camshaft chamber according to the first embodiment of the present invention; 
         FIG. 8  is a cross-sectional view illustrating recycle of lubricant in a rocker arm chamber, as viewed from one angle, according to a second embodiment of the present invention; 
         FIG. 9  is a cross-sectional view illustrating communication of the oil reservoir chamber and the camshaft chamber according to the second embodiment of the present invention; 
         FIG. 10  is a cross-sectional view illustrating recycle of lubricant in the rocker arm chamber, as viewed from another angle, according to the second embodiment of the present invention; 
         FIG. 11  is a cross-sectional view illustrating communication of the camshaft chamber and the crankshaft chamber according to the second embodiment of the present invention; 
         FIG. 12  is a cross-sectional view illustrating layout of a third communicating passage and a fourth communicating passage, independent from each other, according to the second embodiment of the present invention; 
         FIG. 13  is a cross-sectional view illustrating the lubrication apparatus for an engine according to a third embodiment of the present invention; 
         FIG. 14  is a cross-sectional view illustrating the lubrication apparatus for an engine according to a third embodiment of the present invention, as viewed from a different angle; and 
         FIG. 15  is a cross-sectional view illustrating a common path section for a fifth communicating passage and a sixth communicating passage according to the third embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Referring to  FIGS. 1 to 2 , an exploded view and a cross-sectional view illustrating a lubrication apparatus for an engine according to the present invention, the lubrication apparatus is installed in a four-stroke engine including a cylinder block  21 , an upper crankcase  22 , a lower crankcase  23 , and an oil pan  24 . The upper crankcase  22  and the cylinder block  21  are integrally made in one piece; or on the other hand, are made separately from each other. The lower crankcase  23  and the upper crankcase  22  are configurated correspondingly to each other, and are anchored to each other by bolts. The upper crankcase  22  is formed, at underside, with a concave; and the lower crankcase  23  is formed, both at top and underside, with a concave, respectively. A crankshaft chamber  11  is defined, together, by the lower concave of the upper crankcase  22  and the upper concave of the lower crankcase  23 . An oil reservoir chamber  13  is defined, together, by the lower concave of the lower crankcase  23  and the oil pan  24 . 
     According to the present invention, a crankshaft  29  is arranged in the crankshaft chamber  11 , such that when the engine runs, the crankshaft  29  revolves. The cylinder block  21  is, inside, provided with a piston  25 , and that the crankshaft chamber  11  is communicated with an internal space of the cylinder block  21 , namely is communicated with a space underneath the piston  25 . Inside the cylinder block  21 , there is also provided with a camshaft chamber  12  accommodated with a cam device  28 , and a rocker arm chamber  26  accommodated with a rocker arm assembly  27 , where the camshaft chamber  12  and the rocker arm chamber  26  are communicated with each other directly. The rocker arm assembly  27  is, in a power-connection manner, connected with the cam device  28 , and complies with the piston stroke for a timing control manner, so that air-fuel mixture and inlet/exhaust gas can be controlled. 
     The lubrication apparatus for an engine, according to the embodiment, comprises the crankshaft chamber  11 , the camshaft chamber  12 , and the oil reservoir chamber  13 . The crankshaft chamber  11  includes a crankshaft chamber inlet  111  and a crankshaft chamber outlet  112 . The oil reservoir chamber  13  is provided for storing lubricants, where an oil-suction piping path is provided in the oil reservoir chamber  13 , and the oil reservoir chamber  13  is communicated with the crankshaft chamber  11  through the oil-suction piping path. Concretely speaking, the oil-suction piping path includes, in sequence, a rotatable pipe  15 , an oil-pan built-in passage  16 , a connecting pipe  17 , and a lower-crankcase built-in passage  18 . 
     According to the embodiment, the lower-crankcase built-in passage  18  is in connection with the crankshaft chamber inlet  111 , and the rotatable pipe  15  is pivotally arranged along an axis X of the cylinder block  21 . The rotatable pipe  15  includes three oil-suction orifices  152  located at wall of the rotatable pipe  15  and an air-suction vent  151  at an end of the rotatable pipe  15 . According to various structures for the oil reservoir chamber  13  and a total amount of lubricant to be filled in the oil reservoir chamber  13 , the rotatable pipe  15  is so designed that no matter the engine is situated at any state of declination, the air-suction vent  151  is kept above a surface of the lubricant and is communicated with the oil reservoir chamber  13 , and that at least one of the three oil-suction orifices  152  is kept under the surface of the lubricant. Details of the rotatable pipe  15  will be described later. 
     Further, it should be noted that the oil-suction orifices  152  can be so arranged that under a planar visual angle, all the oil-suction orifices  152  are located at a remotest edge of the rotatable pipe  15 . Preferably, this plane is constituted by the axis X of the cylinder block  21  and an axis Y of the crankshaft  29 . Such a plane happens to be a plane on which the engine is posed rightly. By way of such an arrangement for the oil-suction orifices  152 , the object of the present invention, i.e. “appropriate lubrication can be applied to the engine even though the engine is situated at various angles of declination” can be achieved easily.  FIG. 2  shows clearly a relationship of the special arrangement of the oil-suction orifices  152 . 
     A first one-way valve  19  is arranged between the crankshaft chamber  11  and the oil reservoir chamber  13 , where a valve inlet  191  and a valve outlet  192  of the first one-way valve  19  are communicated, respectively, with the crankshaft chamber outlet  112  and the oil reservoir chamber  13 , such that the lubricant can backflow from the crankshaft chamber  11 , through a specific path, into the oil reservoir chamber  13 . 
     Now referring to  FIG. 3 , a cross-sectional view illustrating the rotatable pipe according to the first embodiment of the present invention, the rotatable pipe  15  includes a C-shaped tube  15   a  and a straight tube  15   b,  wherein the straight tube  15   b  is provided with an upper portion  154  and a lower portion  153  which are opposite to each other, and independent from each other. The lower portion  153  is communicated with the C-shaped tube  15   a,  whereas the upper portion  154  is provided with a side opening  155 . The rotatable pipe  15  can be pivotal such that the C-shaped tube  15   a  pivots about the straight tube  15   b.  Preferably, the side opening  155  is located adjacent to a center of the oil reservoir chamber  13  and slightly above the surface of the lubricant. 
     Now referring to  FIGS. 4 and 6 , cross-sectional views illustrating recycle of lubricant in the rocker arm chamber  26 , as viewed from different angles, according to the present invention, the rocker arm chamber  26  is, through a first communicating passage  14 , communicated with the crankshaft chamber  11 . A second one-way valve  31  is arranged in the first communicating passage  14 , such that the second one-way valve  31  opens toward the crankshaft chamber  11 , namely, a valve inlet  311  is communicated with the rocker arm chamber  26  and a valve outlet  312  with the crankshaft chamber  11 . As shown in  FIG. 4 , position P and position Q (indicates an outlet of the first communicating passage  14 ) are independent and separated from each other, though actually both the two positions P,Q are in the first communicating passage  14 . The interrelation between the two positions P,Q can be clarified if reference is made to  FIG. 6 . 
     Further, referring to  FIG. 7 , a cross-sectional view illustrating recycle of lubricant in the camshaft chamber according to the first embodiment of the present invention, the camshaft chamber  12  is, through a second communicating passage  30 , communicated with the oil reservoir chamber  13 . To the effect, the upper portion  154  of the rotatable pipe  15  is connected to a passage inside the lower crankcase  23 . Namely, lubrication-recycle paths of the rocker arm chamber  26  and of the camshaft chamber  12  are all constituted by the upper portion  154  of the rotatable pipe  15  together with built-in passages formed in the lower crankcase  23 , the upper crankcase  22 , and the cylinder block  21 . 
     Referring to  FIG. 5 , a cross-sectional view illustrating lubricant applied in the camshaft chamber/rocker arm chamber according to the first embodiment of the present invention, a view taken from a view angle different from that taken from  FIG. 4 , it is noted that the path for flowing the lubricant for lubricating the camshaft chamber  12  is the same as the path for recycling the lubricant, and this is achieved by the second communicating passage  30 . Because the art of oil passage built in the crankcase has been well known, no further description therefor is necessary. 
     As shown in  FIGS. 2 ,  4  and  7 , during a rising stroke of the piston  25 , a negative-pressure status is produced in the crankshaft chamber  11 . Due to the negative pressure, air is sucked into the oil-suction piping path through the air-suction vent  151 , a pressure difference produced by a rapid flow of the air in the narrowed piping path will atomize the lubricant sucked through the oil-suction orifices  152 . The atomized lubricant in the oil reservoir chamber  13  will, through the oil-suction piping path, reach to the crankshaft chamber  11 , so that components inside the engine can be lubricated.  FIG. 2  shows that during a rising stroke of the piston  25 , the lubricant, due to the pressure difference, will not flow back into the oil reservoir chamber  13  from the first one-way valve  19 . 
     On the other hand, the lubricant in the camshaft chamber  12  and in the rocker arm chamber  26 , due to a positive pressure difference against the oil reservoir chamber  13 , can flow back into the oil reservoir chamber  13  through the second communication passage  30  and the side opening  155 , relating to a recycle for the lubricant. In  FIG. 7 , arrows indicate a flowing direction of the lubricant at this stage. 
     It should be noted that at this stage, there still is a positive pressure difference for the rocker arm chamber  26  against the crankshaft chamber  11 , part of the lubricant in the rocker arm chamber  26  will flow into the crankshaft chamber  11  through the first communicating passage  14  and the second one-way valve  31 . In other words, the rocker arm chamber  26  can use the first communicating passage  14  as a path for flowing the lubricant back into the crankshaft chamber  11  for purpose of appropriate oil discharge. Further, when the engine stands at a normal angle of use, the lubricant in the rocker arm chamber  26  and the camshaft chamber  12 , at this stage, is still possible to flow back into the oil reservoir chamber  13 , due to gravity, through the second communicating passage  30 . 
     Now referring to  FIGS. 2 and 5 , it should be noted that in spite of the fact that  FIG. 2  shows schematically a rising stroke of the piston  25 , this figure is only used for explaining as to how, under the same structure, the engine is to be lubricated during a descending stroke. When the piston  25  is under a descending stroke, the crankshaft chamber  11  produces, through the same structure as shown in  FIG. 2 , a positive pressure. The positive pressure is so functioned as to discharge, from the crankshaft chamber  11 , a great amount of the lubricant to the oil reservoir chamber  13  through the first one-way valve  19 . 
     On the other hand, the lubricant in the oil reservoir chamber  13 , due to a negative pressure difference for the camshaft chamber  12  and the rocker arm chamber  26  against the oil reservoir chamber  13 , can flow to the camshaft chamber  12  and the rocker arm chamber  26  through the side opening  155 , the upper portion  154 , and the second communicating passage  30  so as to lubricate the cam device  28  and the rocker arm assembly  27 . In the meantime, the second one-way valve  31  in the first communicating passage  14  will stop the lubricant flowing from the crankshaft chamber  11  to the rocker arm chamber  26 . Arrows in  FIG. 5  indicates a flowing direction of the lubricant at this stage. 
     In the present invention, a forced lubrication is applied. That is to say, the negative-pressure effect is used to bring the lubricant, during the rising stroke of the piston  25 , to the crankshaft chamber  11  for lubrication; while during the descending stroke of the piston  25 , to bring the lubricant to the camshaft chamber  12  for lubrication. In the meantime, recycle of the lubricant is carried out during the two strokes so as to solve, effectively, the problem of the prior art where quantity of lubricant supplied by the negative-pressure effect for lubricating the engine is much more than what is actually required. 
     Further, referring to  FIGS. 8 and 10 , cross-sectional views illustrating recycle of lubricant in the rocker arm chamber, as viewed from different angles, according to the second embodiment of the present invention, the second embodiment is substantially similar to the first embodiment, in terms of structure, except that a one-way relief valve  32  for pressure release is arranged on a third communicating passage  30   a  which acts to communicate the oil reservoir chamber  13  and the camshaft chamber  12 . 
     In the second embodiment of the present invention, as described for the first embodiment, the rocker arm chamber  26  is, through the first communicating passage  14 , communicated with the crankshaft chamber  11 . The second one-way valve  31  is arranged in the first communicating passage  14 , such that the second one-way valve  31  opens toward the crankshaft chamber  11 , namely, the valve inlet  311  is communicated with the rocker arm chamber  26  and the valve outlet  312  with the crankshaft chamber  11 . For clear understanding purpose, position P and position Q shown in  FIG. 8  can correspond to those shown in  FIG. 10 . 
     Now referring to  FIGS. 2 ,  9 , and  11 ,  FIG. 9  is a cross-sectional view illustrating communication of the oil reservoir chamber and the camshaft chamber,  FIG. 11  is a cross-sectional view illustrating communications between the camshaft chamber and the crankshaft chamber according to the second embodiment of the present invention, a fourth communicating passage  113   a  is interposed between the crankshaft chamber  11  and the camshaft chamber  12 . The third communicating passage  30   a  is provided between the oil reservoir chamber  13  and the camshaft chamber  12 ; and that in the third communicating passage  30   a  there is provided with the one-way relief valve  32 , with a valve inlet  321  communicated with the oil reservoir chamber  13 , and with a valve outlet  322  communicated with the camshaft chamber  12 . 
     When the piston  25  is under a descending stroke, the crankshaft chamber  11  has a pressure greater than that of the camshaft  12 . After lubricating relevant components of the crankshaft chamber  11 , the lubricant, on the one hand, through the first one-way valve  19 , flows back into the oil reservoir chamber  13  in a great amount; and on the other, a little amount of the lubricant is delivered, through the fourth communicating passage  113   a,  to the camshaft chamber  12  to lubricate relevant components. 
     In the meantime, the positive pressure of the crankshaft chamber  11  exerting on the oil reservoir chamber  13  will force and release the pressure of the oil reservoir chamber  13  to the camshaft chamber  12  through the upper portion  154  of the rotatable pipe  15 , the one-way relief valve  32 , and the third communicating passage  30   a.    
     At this stage, the second one-way valve  31  (see  FIG. 10 ) of the first communicating passage  14  acts to retard the lubricant flowing from the crankshaft chamber  11  to the rocker arm chamber  26 , so that an inappropriate and additional amount of the lubricant can be avoided. 
     Further referring to  FIGS. 2 ,  8  and  10 , when the piston  25  is at a rising stroke, the crankshaft chamber  11  will be subject to a negative pressure. Under the circumstances, the oil-suction piping path will suck in air through the air-suction vent  151 , so that the air flowing rapidly in the narrower piping path will produce a pressure difference, making the lubricant entering into the oil-suction orifices  152  atomized. The atomized lubricant in the oil reservoir chamber  13  will reach to the crankshaft chamber  11  through the oil-suction piping path, so that components inside the engine can be lubricated. The lubricant inside the engine will not flow back to the oil reservoir chamber  13  through the first one-way valve  19 . 
     Further, at this moment the camshaft chamber  12  has a pressure greater than that of the crankshaft chamber  11 , and because the lubricant in the camshaft chamber  12  cannot flow reversely back to the oil reservoir chamber  13  through the one-way relief valve  32 , the lubricant in the camshaft chamber  12 , due to a pressure difference, is sucked back to the crankshaft chamber  11  through the fourth communicating passage  113   a.    
     At this stage, the rocker arm chamber  26 , relative to the crankshaft chamber  11 , has a positive pressure difference. As such, part of the lubricant in the rocker arm chamber  26  will flow into the crankshaft chamber  11  through the first communicating passage  14  and the second one-way valve  31 . In other words, the rocker arm chamber  26  can use the first communicating passage  14  as a path for flowing the lubricant back to the crankshaft chamber  11  so as to discharge the lubricant effectively. 
     References may be made to  FIGS. 8 ,  9  and  11 , and to  12 , a cross-sectional view illustrating layout of the third communicating passage  30   a  and the fourth communicating passage  113   a  independent from each other according to the second embodiment of the present invention. Location marks M 1 , N 1 , F, and G are employed for explanation conveniently. 
     Referring to  FIG. 13 , a cross-sectional view illustrating a lubrication apparatus for an engine according to a third embodiment of the present invention, to  FIG. 14 , a cross-sectional view illustrating the lubrication apparatus for an engine according to the third embodiment of the present invention, as viewed from a different angle; and to  FIG. 15 , a cross-sectional view illustrating a common section for a fifth communicating passage and a sixth communicating passage according to the third embodiment of the present invention, this embodiment is similar to the second embodiment, except that the former adopts a three-way path to communicates the crankshaft chamber  11 , the oil reservoir chamber  13 , and the camshaft chamber  12 . There are provided with first, second and third path sections P 1 , P 2 , P 3  extending from an intersection O, wherein the first path section P 1  is communicated with the crankshaft chamber  11 , the second path section P 2  with the camshaft chamber  12 , and the third path section P 3  with the oil reservoir chamber  13 . 
     Therefore, the camshaft chamber  12  and the oil reservoir chamber  13  are communicated with each other through the second path section P 2  and the third path section P 3  which constitute a fifth communicating passage  30   b;  whereas the camshaft chamber  12  and the crankshaft chamber  11  are communicated with each other through the first path section P 1  and the second path section P 2  which constitute a sixth communicating passage  113   b.  The third one-way valve  32  of the fifth communicating passage  30   b  is arranged in the third path section P 3 . Both the fifth and the sixth communicating passages  30   b,    113   b  have a common path section, i.e. the second path section P 2 . 
     Of course, the path for pressure release can alternatively be an external piping path, and it is not intended to limit it to the built-in version in the embodiment. 
     Although the present invention has been explained in relation to its preferred embodiments, it is to be understood that many other possible modifications and variations can be made without departing from the scope of the invention as hereinafter claimed.