Abstract:
To provide an oil receiver in which friction on a shaft body generated in association with introduction of hydraulic pressure into the oil receiver is alleviated. Therefore, the amount of fuel consumption is reduced and durability is improved. Furthermore, the number of components is reduced, and thus manufacturing and assembly costs can be reduced. An oil receiver includes a connecting oil passage in communication with an inside of the shaft body via a communication hole formed in the shaft body. A lead-in oil passage for introducing lubricating oil into the connecting oil passage extends from the connecting oil passage radially outward. A balance oil passage extends from the connecting oil passage radially outward on an opposite side of the connecting oil passage from the lead-in oil passage. The balance oil passage is closed at an extremity thereof. Accordingly, lubricating oil can be introduced from the lead-in oil passage into the inside of the shaft body.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
   This nonprovisional application claims priority under 35 U.S.C. § 119(a) on patent application Nos. 2001-399538, filed in Japan on Dec. 28, 2001, the entirety of which is hereby incorporated by reference. 

   BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The present invention relates to an oil receiver for introducing lubricating oil into a shaft body from the outside. 
   2. Description of Background Art 
   When introducing lubricating oil into a shaft body from the outside, an oil receiver is provided for supplying lubricating oil. The oil receiver includes a connecting oil passage formed on the outer periphery of the shaft body which communicates with a communication hole extending from the inside to the outside of the shaft body. 
   For example, in the case of an aircraft, hydraulic pressure for varying the pitch of the propeller is supplied through an oil passage located inside the revolving shaft of the propeller. An oil receiver is formed around the outer periphery of the revolving shaft of the propeller for introducing lubricating oil from an external hydraulic pressure varying unit into the oil passage inside the revolving shaft of the propeller. 
   The construction of an oil receiver according to the background art is illustrated in  FIGS. 6 and 7  of the present invention. 
   Referring to  FIGS. 6 and 7 , the crankshaft  03  of the internal combustion engine directly rotates a propeller. The crankshaft  03  is rotatably supported by the cylinder block  01  of the internal combustion engine via a bearing  02 . The crankshaft  03  is cylindrical in shape and is fitted therein with an inner cylinder  04 . The clearance between the crankshaft  03  and the inner cylinder  04  is used as the oil passage  05 . 
   The communication holes  06  open at positions upstream of the oil passage  05  and are formed, for example, at every 180° circumferentially of the crankshaft  03 . An oil receiver  07  is mounted so as to cover the plurality of communication holes  06  on the outer periphery of the crankshaft  03 . 
   The oil receiver  07  forms an annular oil passage  08  along the outer peripheral surface of the crankshaft  03 . The aforementioned two communication holes  06  communicate with the annular oil passage  08 . 
   A lead-in oil passage  09  extends integrally from a part of the annular oil passage  08  radially outward. An extremity of the lead-in oil passage  09  is fitted and connected in a joint pipe  01   a , which projects from the inner surface of the cylinder block  01  in a liquid-tight manner. 
   Lubricating oil supplied from the hydraulic pressure varying unit is introduced into the annular oil passage  08  from the joint pipe  01   a  through the lead-in oil passage  09 . The lubricating oil then flows into the oil passage  05  in the crankshaft  03  through the communication holes  06 , and reaches the propeller pitch varying unit at the propeller boss at the extremity of the crankshaft. Accordingly, the pitch of the propeller can be varied. 
   The oil receiver  07  is fixed in contrast to the rotating crankshaft  03  and is in sliding contact with the crankshaft  03 . Furthermore, the oil receiver  07  is formed with a stopper  07   a , which is to be locked by a part of the cylinder block  01  for preventing the oil receiver  07  from rotating together with the crankshaft  03 . 
   The oil receiver  07  is divided into two halves and includes a left half and the right half. The respective oil receiver halves  07 L,  07 R clamp the crankshaft  03  from the left and the right. The fastening bosses on the top and bottom are fastened with bolts  010 ,  011 . The lead-in oil passage  09  is formed integrally on the right oil receiver half  07 R (left side in FIG.  7 ). 
   The hydraulic pressure introduced into the lead-in oil passage  09  of the oil receiver  07  is introduced from the joint pipe  01   a . Accordingly, the hydraulic pressure in the joint pipe  01   a  is applied on the end surface of the opening of the lead-in oil passage  09 . This pressure P constantly presses the right oil receiver half  07 R leftward (rightward in FIG.  7 ), which increases friction with respect to the crankshaft  03 , which is in sliding contact therewith. As a consequence, the amount of consumption of fuel may increase and the progression of abrasion may be accelerated. 
   The oil receiver  07  is prevented from being rotated together with the rotation of the crankshaft  03  by the lead-in oil passage  09  fitted into the joint pipe  01   a  of the cylinder block  01 . However, this is an insufficient way to prevent rotation of the oil receiver  07 . Accordingly, the stopper  07   a  is also separately locked by a part of the cylinder block. 
   The lead-in oil passage  09  is formed integrally on the right oil receiver half  07 R, and the stopper  07   a  is formed integrally on the left oil receiver half  07 L. Therefore, the left and right oil receiver halves  07 L,  07 R are not symmetrical, and hence are not identical in shape. As a consequence, two types of oil receiver halves must be provided. 
   SUMMARY OF THE INVENTION 
   In view of the above, it is an object of the present invention to provide an oil receiver in which friction with respect to the shaft body generated in association with introduction of the hydraulic pressure into the oil receiver is alleviated. Therefore, the amount of fuel consumption can be reduced and durability can be improved. Furthermore, it is an object of the present invention to reduce the number of necessary components to reduce manufacturing and assembly costs. 
   In order to achieve the aforementioned object, according to a first aspect of the present invention, an oil receiver includes a connecting oil passage in communication with an inside of a shaft body via a communication hole formed on an outer periphery of the shaft body. A lead-in oil passage is provided for introducing lubricating oil into the aforementioned connecting oil passage. The lead-in oil passage extends from the connecting oil passage radially outward. Lubricating oil is introduced from the lead-in oil passage into the inside of the shaft body. A balance oil passage extends integrally from the connecting oil passage radially outward on an opposite side thereof, symmetrically with the lead-in oil passage. The balance oil passage is closed at an extremity thereof. 
   The balance oil passage, which has a closed extremity, is provided symmetrically with the lead-in oil passage. Accordingly, the pressure of the pressurized oil applied on the end surface of the opening of the lead-in oil passage and the pressure applied on the end surface of the opening at the extremity of the balance oil passage are the same. Accordingly, the pressures are cancelled out, and thus the oil receiver is balanced at a center thereof As a consequence, friction with respect to the shaft body is alleviated, the amount of fuel consumption is reduced, the progression of abrasion can be prevented, and durability can be improved. 
   According to a second aspect of the present invention, the oil receiver is adapted to be divided into two halves along a symmetry plane of the lead-in oil passage and the balance oil passage that are axially symmetrical. Furthermore, the divided oil receiver halves are identical in shape. 
   Since the divided oil receiver halves are identical in shape, the number of different components is reduced. Therefore, a reduction in manufacturing and assembly costs can be achieved. 
   According to a third aspect of the present invention, the extremity of the lead-in oil passage and the extremity of the balance oil passage are fitted into the symmetrical joint pipes on the fixed support in a liquid-tight manner. Furthermore, the joint pipe, in which the extremity of the balance oil passage is fitted, is closed. 
   The extremities of the lead-in oil passage and the balance oil passage are fitted in the symmetrical joint pipes on the fixed support in a liquid-tight manner respectively. Accordingly, the movement of the oil receiver in association with the movement of the shaft body may easily be prevented without providing a stopper even when the shaft body rotates with respect to the fixed support. In addition, since it is not a cantilevered type as in the background art, local abutment of the oil receiver due to leaning of the oil receiver can be prevented even when the shaft body is slid in the axial direction. 
   According to a fourth aspect of the present invention, the shaft body is a crankshaft of an internal combustion engine for an aircraft. A hydraulic pressure varying unit is provided upstream of the aforementioned lead-in oil passage. Furthermore, a propeller pitch varying unit for varying the pitch of the propeller by hydraulic pressure is provided downstream of the oil passage formed in the crankshaft in the direction of the axis of the communication hole. 
   In an aircraft, the crankshaft of the internal combustion engine is adapted to rotate the propeller directly. Therefore, the hydraulic pressure of the hydraulic pressure varying unit is introduced from the lead-in oil passage into the connecting oil passage of the oil receiver, and then fed through the communication hole into the oil passage in the rotating crankshaft. The hydraulic pressure acts on the propeller pitch varying unit located downstream thereof to vary the pitch of the propeller. 
   The extremities of the lead-in oil passage and the balance oil passage are fitted into the symmetrical joint pipes on the fixed support in a liquid-tight manner, even when the shaft body is a rotating shaft such as a crankshaft. Accordingly, the oil receiver can easily be prevented from being rotated in association with the rotation of the crankshaft without providing a stopper. 
   Further scope of applicability of the present invention will become apparent from the detailed description given hereinafter. However, it should be understood that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The present invention will become more fully understood from the detailed description given hereinbelow and the accompanying drawings which are given by way of illustration only, and thus are not limitative of the present invention, and wherein: 
       FIG. 1  is a schematic drawing of a drive section of a propeller for an aircraft according to an embodiment of the present invention; 
       FIG. 2  shows a cross sectional view of a crankshaft in the vicinity of a front end portion taken along a vertical line, and a schematic view of an oil passage for lubricating oil; 
       FIG. 3  is a cross sectional view of a crankshaft in the vicinity of a front end portion taken along a horizontal line; 
       FIG. 4  is a cross sectional view taken along the line IV—IV in  FIG. 3 ; 
       FIG. 5  is a cross sectional view showing another example of the present invention; 
       FIG. 6  is a cross sectional view of a crankshaft of the background art in the vicinity of a front end portion thereof taken along a horizontal line; and 
       FIG. 7  is a cross sectional view taken along the line VII—VII in FIG.  6 . 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   Referring now to  FIGS. 1  to  4 , an embodiment of the present invention will be described. The oil receiver according to the present embodiment is applied to the crankshaft  12  of the internal combustion engine  10  of the aircraft  1 . The oil receiver corresponds to a part of the oil passage for lubricating oil used for varying the pitch of a propeller  4 . 
   General construction of the drive section of the propeller  4  for an aircraft  1  is shown in  FIG. 1. A  propeller boss  3  projects from the front end of the engine compartment  2  of the aircraft  1 . A plurality of propellers  4  project in the radial direction from the propeller boss  3  so as to be capable of varying the propeller pitch (blade angle) as is known in the art. 
   A horizontally opposed 4-cylinder internal combustion engine  10  is mounted in the engine case  2 . The crankshaft  12  projects forward from the cylinder block  11  and is coaxially connected to the propeller shaft  5  of the propeller boss  3  by fastening the flanges  12   a ,  5   a  with each other with bolts. 
   The construction of the crankshaft  12  in the vicinity of the front end portion will be shown in  FIGS. 2  to  4 .  FIG. 2  shows a cross sectional view of the crankshaft  12  in the vicinity of the front end portion taken along a vertical line, and a schematic view of the oil passage for lubricating oil.  FIG. 3  is a cross sectional view of the crankshaft  12  in the vicinity of the front end portion taken along a horizontal line. 
   The crankshaft  12  is rotatably supported by the cylinder block  11  via the bearing  13 . The crankshaft  12  projects forward from a forward swelled out portion, and is provided with a flange  12   a  at the front portion. The crankshaft  12  is cylindrical and is fitted with an inner cylinder  14  therein. The clearance formed between the crankshaft  12  and the inner cylinder  14  is used as an oil passage  15 . 
   A part of the rear portion of the inner cylinder  14  is broadened to form a sealing portion  14   a . Lubricating oil is fed forward through the oil passage  15 . Communication holes  16  open at positions upstream (near the sealing portion  14   a ) of the oil passage  15 . The communication holes  16  are formed in crankshaft  12  at symmetrical positions at an angle of 180° in the circumferential direction (three or more communication holes  16  may be formed). An oil receiver  20  is mounted on the outer periphery of the crankshaft  12  so as to cover the plurality of communication holes  16 . 
   The oil receiver  20  is formed by combining the left and right oil receiver halves  20 L,  20 R, clamping the crankshaft  12  therebetween. The left and right oil receiver halves  20 L,  20 R are identical in shape and include semi-circular portions  20 La,  20 Ra, straight tubes  20 Lb,  20 Rb projecting radially outwardly from the center of the respective semi-circular portions  20 La,  20 Ra, and fastening bosses  20 Lc,  20 Rc formed at both ends of the respective semi-circular portions  20 La,  20 Ra. 
   The left and right oil receiver halves  20 L,  20 R are combined by abutting the mating surfaces of the upper and lower fastening bosses  20 Lc,  20 Rc with each other in such a manner that the crankshaft  12  is clamped by the semi-circular portions  20 La,  20 Ra from the left and the right. The fastening bosses  20 Lc,  20 Rc are then fastened together with bolts  25 ,  26 . 
   The semi-circular portions  20 La,  20 Ra and the crankshaft  12  are in contact with each other so as to be capable of rotating with respect to each other. A groove formed circumferentially along the inner peripheral surface of the semi-circular portions  20 La,  20 Ra forms an annular oil passage  21  with the outer peripheral surface of the crankshaft  12 . This annular oil passage  21  corresponds to the connecting oil passage, and communicates with the aforementioned communication hole  16  formed in the crankshaft  12 . 
   The straight tube  20 Rb of the right (left in  FIG. 4 ) oil receiver half  20 R constitutes a lead-in oil passage  22  and communicates with the annular oil passage  21 . The straight tube  20 Lb of the left oil receiver half  20 L constitutes the balance oil passage  23  and communicates with the annular oil passage  21 . 
   On the inner peripheral surface of the cylinder block  11 , joint pipes  11   a ,  11   b  project toward the straight tubes  20 Lb,  20 Rb projecting from the oil receiver  20  toward the left and right. The inner diameters of the joint pipes  11   a ,  11   b  are identical with the outer diameters of the opening ends of the extremities of the straight tubes  20 Lb,  20 Rb. Therefore, the straight tubes  20 Lb,  20 Rb may be fitted and joined into the joint pipes  11   a ,  11   b  via the seal member in a liquid-tight manner. 
   The joint pipe  11   b  to which the straight tube  20 Rb that constitutes the lead-in oil passage  22  is fitted is in communication with the oil feed path  24 . The joint pipe  11   a  to which the straight tube  20 Lb that constitutes the balance oil passage  23  is fitted is closed. 
   Therefore, the hydraulic pressure supplied from the oil feed path  24  into the joint pipe  11   b  is introduced into the annular oil passage  21  of the oil receiver  20  through the lead-in oil passage  22 . The hydraulic pressure is then introduced from the annular oil passage  21  into the oil passage  15  in the crankshaft  12  via the communication hole  16 , fed along the oil passage  15  forward in the crankshaft  12 , and then forward in the propeller shaft  5  to act on the propeller pitch varying unit in the propeller boss  3 . 
   Provided upstream of the oil feed path  24  that feeds the hydraulic pressure to the oil receiver  20  is, as schematically shown in  FIG. 2 , a propeller governor  31  that corresponds to a hydraulic pressure varying unit. The propeller governor  31  is supplied with lubricating oil from the main gallery  32  formed in the cylinder block  11 . 
   The oil pan  33  is disposed downwardly of the cylinder block  11 . Lubricating oil tapped in the oil pan  33  is adsorbed by the oil pump  35  through the strainer  34 . The lubricating oil discharged from the oil pump  35  is supplied to the aforementioned main gallery  32  via the oil filter cartridge  36 . 
   When the propeller governor  31  is set in a predetermined state by the operation of the propeller pitch lever, not shown, it adjusts the hydraulic pressure automatically for allowing it to act upon the propeller pitch varying unit in the propeller boss  3  via the oil receiver  20  to vary the pitch of the propeller. The propeller governor  31  then automatically controls the revolution of the internal combustion engine to be at a predetermined constant revolution. 
   In the route of lubricating oil for varying the propeller pitch, the oil receiver  20  includes the balance oil passage  23  provided symmetrical to the lead-in oil passage  22 . The balance oil passage  23  is closed at an extremity thereof as shown in FIG.  4 . Therefore, the pressure P applied on the end surface of the opening of the lead-in oil passage  22  for the pressurized oil and the pressure P′ applied on the end surface of the opening at the extremity of the balance oil passage  23  are the same in a direction toward each other. Therefore, these pressures are canceled out at the mating surfaces between the left and right oil receiver halves  20 L,  20 R, and thus the oil receiver  20  may be positioned at the well balanced center. 
   Therefore, friction generated between the oil receiver  20  and the crankshaft  12  is alleviated, and the amount of fuel consumption is reduce, thereby preventing the progression of abrasion and improving durability. 
   Since the divided oil receiver halves  20 L,  20 R are identical in shape, the number of components may be reduced and thus the costs may be reduced. 
   The respective extremities of the straight tubes  20 Lb,  20 Rb projecting from the oil receiver halves  20 L,  20 R to be combined toward the left and the right are fitted into the joint pipes  11   a ,  11   b  formed symmetrically on the cylinder block  11  in a liquid-tight manner. Accordingly, the oil receiver  20  can be easily prevented from being rotated in association with the rotation of the crankshaft  12  without providing a separate stopper. 
   In the embodiment described thus far, pressurized oil is introduced from the lead-in oil passage  22  through the oil feed path  24 . It is also possible to also provide an oil feed path  54  on the balance oil passage  23  so as to be symmetrical to the oil feed path  24  as shown in FIG.  5 . Hydraulic pressure is also supplied from the propeller governor  31  to the oil feed path  54 . 
   Forming the oil passage from the propeller governor  31  through both oil feed paths  24 ,  54  to the lead-in oil passage  22  and the balance oil passage  23  completely symmetrical with each other allows simultaneous supply of the same hydraulic pressure to the lead-in oil passage  22  and to the balance oil passage  23 . Therefore, the oil receiver  20  can be constantly positioned at the well balanced center, thereby reducing friction generated between the oil receiver  20  and the crankshaft  12 . 
   When feeding of lubricating oil to the oil receiver  20  is begun at the time of starting the internal combustion engine, the identical hydraulic pressure is simultaneously supplied to the lead-in oil passage  22  and to the balance oil passage  23 . Therefore, the oil receiver  20  can be positioned at the well balanced center at startup and at the moment immediately after the engine is started. 
   The invention being thus described, it will be obvious that the same may be varied in many ways. Such variations are not to be regarded as a departure from the spirit and scope of the invention, and all such modifications as would be obvious to one skilled in the art are intended to be included within the scope of the following claims.