(19)
(11) EP 2 816 204 A1

(12) EUROPEAN PATENT APPLICATION

(43) Date of publication:
24.12.2014 Bulletin 2014/52

(21) Application number: 14171085.5

(22) Date of filing: 04.06.2014
(51) International Patent Classification (IPC): 
F01M 1/08(2006.01)
F02F 3/22(2006.01)
F01P 3/08(2006.01)
(84) Designated Contracting States:
AL AT BE BG CH CY CZ DE DK EE ES FI FR GB GR HR HU IE IS IT LI LT LU LV MC MK MT NL NO PL PT RO RS SE SI SK SM TR
Designated Extension States:
BA ME

(30) Priority: 12.06.2013 JP 2013123386

(71) Applicant: Honda Motor Co., Ltd.
Minato-ku Tokyo 107-8556 (JP)

(72) Inventors:
  • Kawakubo, Shinsuke
    Saitama, Saitama 351-0193 (JP)
  • Tsuchiya, Ryuji
    Saitama, Saitama 351-0193 (JP)

(74) Representative: Quinterno, Giuseppe et al
Corso Emilia 8
10152 Torino
10152 Torino (IT)

   


(54) Mounting structure for piston cooling oil jetting device in internal combustion engine


(57) A piston cooling oil jetting device (60) is fastened to a crankcase (31) which is provided with an arm portion mounting fastening boss (65) to which a screw engagement member (64) is fastened. A fastening surface (65a) of the arm portion mounting fastening boss (65) and a main body portion mounting surface (65b) of a main body portion (61) of the jetting device (60) are connected to each other through a contact surface portion (65c) extending along the axial direction of the screw engagement member (64). A fastening arm portion (63) of the jetting device (60) is formed along the contact surface portion (65c) of the arm portion mounting fastening boss (65). In a state where the piston cooling oil jetting device (60) is fixed to the crankcase (31), at least one part of the fastening arm portion (63) of the jetting device (60) is in contact with the contact surface portion (65c).




Description


[0001] The present invention relates to a mounting structure for a piston cooling oil jetting device in an internal combustion engine.

[0002] There has been a mounting structure wherein a piston cooling oil jetting device (oil jet) for jetting an oil toward an inside surface of a top portion of a piston in an internal combustion engine so as to cool the inside surface is mounted to an inner surface of a crankcase or of a cylinder block (see Japanese Patent Laid-Open No. 2011-208581).

[0003] The oil jetting device in the above-mentioned document includes: a jetting device main body portion having an oil channel capable of communicating, in a fittable and detachable manner, with an oil passage provided in the crankcase or the cylinder block; a nozzle portion which integrally extends from the jetting device main body portion toward the piston in a cylinder bore and which has an oil jet port; and a flange portion which is formed integrally with the jetting device main body portion and which has a contact surface capable of making flush contact with the crankcase inner surface or the cylinder block inner surface. In this structure, the direction of extension of the nozzle portion is parallel to the contact surface that makes flush contact with the crankcase inner surface. The jetting device main body portion and the flange portion are disposed on a continuous surface in the crankcase or the cylinder block, in other words, disposed on the same plane surface.

[0004] In the case of mounting the oil jetting device onto the crankcase inner surface, therefore, there may arise the following problem. When a bolt to be put into screw engagement with the crankcase or the cylinder block by penetrating the flange portion is tightened, the main body portion is liable to rotate together with the bolt attendantly on the rotation of the bolt. Thus, a force in the rotating direction is exerted on the main body portion, whereby a positional error or falling of the main body portion is liable to be brought about. As a result, a sealing property between the crankcase and the main body portion may become non-uniform, or oil jetting accuracy may be lowered due to the positional error of the main body portion.

[0005] It is an object of the present invention to provide a piston cooling oil jetting device by which an oil can be reliably supplied to an inside surface of a piston in an internal combustion engine.

[0006] According to the invention as set forth in claim 1, there is provided a mounting structure for a piston cooling oil jetting device, including
a piston cooling oil jetting device (60) fastened and fixed to a crankcase (31) by a screw engagement member (64), the piston cooling oil jetting device (60) including:

a main body portion (61) having an oil channel communicating with an oil passage (56) provided in the crankcase (31);

a nozzle portion (62) extending from the main body portion (61) toward a piston (45) in a cylinder bore (44), the nozzle portion (62) having an oil jet port (62a); and

a fastening arm portion (63) provided to project from the main body portion (61), the fastening arm portion (63) formed therein with an insertion hole (63d) through which the screw engagement member (64) is inserted and passed.



[0007] The present mounting structure for the piston cooling oil jetting device is characterized in that:

the crankcase (31) is provided with an arm portion mounting boss (65) to which the screw engagement member (64) is fastened, and a main body portion mounting hole (65f) into which the main body portion (61) is mounted;

a fastening surface (65a) of the arm portion mounting boss (65) and a main body portion mounting surface (65b) of the main body mounting hole (65f) are formed on planes different in height with respect to an axial direction of the screw engagement member (64) taken as a height direction; and

the fastening surface (65a) and the main body portion mounting surface (65b) are connected to each other through a contact surface portion (65c) extending along the axial direction of the screw engagement member (64).



[0008] The present mounting structure for the piston cooling oil jetting device is characterized also in that:

the fastening arm portion (63) is formed along the contact surface portion (65c) of the arm portion mounting boss (65);

at least one part (63a) of the fastening arm portion (63) is in contact with the contact surface portion (65c) in a state where the piston cooling oil jetting device (60) is fixed to the crankcase (31); and

one end part (63b) of the fastening arm portion (63) is fastened to the fastening surface (65a).



[0009] According to the invention as set forth in claim 2, there is provided the mounting structure for the piston cooling oil jetting device as described in claim 1, characterized in that:

the contact surface portion (65c) is formed to have a plane surface substantially parallel to an axis of the screw engagement member (64); and

the one part (63a), formed in a plate-like shape, of the fastening arm portion (63) makes contact with the plane surface.



[0010] According to the invention as set forth in claim 3, there is provided the mounting structure for the piston cooling oil jetting device as described in claim 2, characterized in that
another end part (63c) of the fastening arm portion (63) is set in pressure contact with the main body portion mounting surface (65b).

[0011] According to the invention as set forth in claim 4, there is provided the mounting structure for the piston cooling oil jetting device as described in any of claims 1 to 3, characterized in that:

the crankcase (31) is configured to be divisible into a first case half (32) and a second case half (33); and

the fastening surface (65a) is formed on a same plane with a parting face of the crankcase (31).



[0012] According to the invention as set forth in claim 5, there is provided the mounting structure for the piston cooling oil jetting device as described in claim 4, characterized in that:

the parting face of the crankcase (31) is provided on a cylinder axis (G);

the fastening surface (65a) is formed on a same plane with the parting face of either one crankcase half of the first case half (32) and the second case half (33); and

the main body portion mounting surface (65b) is formed on an inside wall surface which is part of the one crankcase half and which is spaced from the cylinder axis.



[0013] According to the invention as set forth in claim 6, there is provided the mounting structure for the piston cooling oil jetting device as described in any of claims 1 to 4, characterized in that:

the crankcase (31) is configured to be divisible into a first case half (32) and a second case half (33); and

a case connecting fastening boss (22) is formed so that the first case half (32) and the second case half (33) are connected to each other by a case connecting bolt (23).



[0014] This mounting structure is characterized also in that:

the fastening surface (65a) is formed with the arm portion mounting boss (65) having a fastening hole (65d) corresponding to the insertion hole (63d) formed in the fastening arm portion (63); and

the arm portion mounting boss (65) is provided close to the case connecting fastening boss (22).



[0015] According to the invention as set forth in claim 7, there is provided the mounting structure for the piston cooling oil jetting device as described in any of claims 1 to 6, characterized in that
a stud bolt fastening boss (24) is formed so that internal combustion engine component parts (31, 34) inclusive of a cylinder head (35) are connected to the crankcase (31) by a stud bolt (37).

[0016] This mounting structure is characterized also in that:

the fastening surface (65a) is formed with the arm portion mounting boss (65) having a fastening hole (65d) corresponding to the insertion hole (63d) formed in the fastening arm portion (63); and

the arm portion mounting boss (65) is provided close to the stud bolt fastening boss (24).



[0017] According to the invention as set forth in claim 8, there is provided the mounting structure for the piston cooling oil jetting device as described in any of claims 1 to 7, characterized in that:

the crankcase (31) is configured to be divisible into a first case half (32) and a second case half (33);

a case connecting fastening boss (22) is formed so that the first case half (32) and the second case half (33) are connected to each other by a case connecting bolt (23);

a stud bolt fastening boss (24) is formed so that internal combustion engine component parts (31, 34) inclusive of a cylinder head (35) are connected to the crankcase (31) by a stud bolt (37);

the fastening surface is formed with the arm portion mounting boss (65) having a threaded hole (65e) corresponding to the insertion hole (63d) formed in the fastening arm portion (63); and

the arm portion mounting boss (65) is provided between the case connecting fastening boss (22) and the stud bolt fastening boss (24), closely to the case connecting fastening boss (22) and the stud bolt fastening boss (24).



[0018] According to the invention as set forth in claim 9, there is provided the mounting structure for the piston cooling oil jetting device as described in any of claims 1 to 8, characterized in that:

the oil passage (56) in the crankcase (31) communicates with an oil pump (50); and

an oil discharged from the oil pump (50) is supplied to the main body portion (61) of the piston cooling oil jetting device (60) on a most upstream side which is on an upstream side of a position of branching to other passages.



[0019] According to the invention as set forth in claim 10, there is provided the mounting structure for the piston cooling oil jetting device as described in any of claims 1 to 9, characterized in that:

the cylinder bore (44) is so provided that the cylinder axis (G) is located in a plane orthogonal to a crank axis (C), with an offset to either one of an upper side and a lower side with reference to the crank axis (C); and

the piston cooling oil jetting device (60) is disposed on the offset side of the cylinder bore (44).



[0020] According to the invention as set forth in claim 11, there is provided the mounting structure for the piston cooling oil jetting device as described in any of claims 1 to 10, characterized in that:

the nozzle portion (62) and the piston (45) overlap each other in the direction of the cylinder axis (G) when the piston (45) is in a bottom dead center; and

the piston (45) is formed with a relief recess (45a) for preventing interference thereof with the nozzle portion (62) in the overlapping position.



[0021] In claim 1, the fastening surface 65a of the arm portion mounting boss 65 and the main body portion mounting surface 65b to which the main body portion 61 is mounted are formed on planes different in height with respect to the axial direction of the screw engagement member 64 taken as a height direction. In addition, the fastening surface 65a and the main body portion mounting surface 65b are connected to each other through the contact surface portion 65c extending along the axial direction of the screw engagement 64. Besides, the fastening arm portion 63 is formed along the contact surface portion 65c of the arm portion mounting boss 65. Further, at least one part 63a of the fastening arm portion 63 is in contact with the contact surface portion 65c in a state where the piston cooling oil jetting device 60 is fixed to the crankcase 31. In addition, one end part 63b of the fastening arm portion 63 is fastened to the fastening surface 65a. In the case of mounting the piston cooling oil jetting device 60 onto the crankcase 31, therefore, the main body portion 61 which might rotate together with the screw engagement member 64 attendantly on the rotation of the screw engagement member 64 can be prevented from rotating, by the contact of the one part 63a of the fastening arm portion 63 with the contact surface portion 65c of the arm portion mounting boss 65. This enables easy positioning of the piston cooling oil jetting device 60. Accordingly, the oil jetted from the nozzle portion 62 of the piston cooling oil jetting device 60 can be made to accurately reach a required part of the lower surface of the piston 45.

[0022] In claim 2, the contact surface portion 65c is formed to have a plane surface substantially parallel to the axis of the screw engagement member 64. In addition, the one part 63a, formed in a plate-like shape, of the fastening arm portion 63 makes contact with the plane surface. This ensures that the one part 63a can be enlarged, whereby a further higher mounting accuracy can be obtained.

[0023] In claim 3, the other end part 63c of the fastening arm portion 63 is set in pressure contact with the main body portion mounting surface 65b. This makes it possible to obtain a high accuracy in mounting the piston cooling oil jetting device 60.

[0024] In claim 4, the crankcase 31 is configured to be divisible into the first case half 32 and the second case half 33. In addition, the fastening surface 65a is formed on the same plane with the parting face of the crankcase 31. Therefore, screw thread cutting for fastening of the screw engagement member can be carried out easily. This promises enhanced productivity. Further, a working space for fastening the screw engagement member by use of a tool can be secured easily, so that a fastening work can be carried out easily. Consequently, a further enhanced productivity is realized.

[0025] In claim 5, the parting face of the crankcase 31 is provided on the cylinder axis G. In addition, the fastening surface 65a is formed on the same plane with the parting face of either one crankcase half of the first case half 32 and the second case half 33. Further, the main body portion mounting surface 65b is formed on an inside wall surface which is part of the one crankcase half and which is spaced from the cylinder axis. This configuration ensures that interference of the nozzle portion 62 with the piston 45 moving inside the crankcase 31 or with the connecting rod 47 connected to the piston 45 can be obviated easily.

[0026] In claim 6, the crankcase 31 is configured to be divisible into the first case half 32 and the second case half 33. In addition, the case connecting fastening boss 22 is formed so that the first case half 32 and the second case half 33 are connected to each other by the case connecting bolt 23. Besides, the fastening surface 65a is formed with the arm portion mounting boss 65 having the fastening hole 65d corresponding to the insertion hole 63d formed in the fastening arm portion 63. Further, the arm portion mounting boss 65 is provided close to the case connecting fastening boss 22. This configuration ensures that the rigidity of the arm portion mounting boss 65 can be effectively enhanced by utilizing the existing case connecting fastening boss 22. Consequently, vibration of the piston cooling oil jetting device 60 can be restrained, and oil jetting accuracy can be enhanced.

[0027] In claim 7, the stud bolt fastening boss 24 is formed so that internal combustion engine component parts 31 and 34 inclusive of the cylinder head 35 are connected to the crankcase 31 by the stud bolt 37. In addition, the fastening surface 65a is formed with the arm portion mounting boss 65 having the fastening hole 65d corresponding to the insertion hole 63d formed in the fastening arm portion 63. Further, the arm portion mounting boss 65 is provided close to the stud bolt fastening boss 24. Therefore, the rigidity of the arm portion mounting boss 65 can be effectively enhanced by utilizing the existing stud bolt fastening boss 24. This makes it possible to restrain vibrations of the piston cooling oil jetting device 60, and to enhance oil jetting accuracy.

[0028] In claim 8, the crankcase 31 is configured to be divisible into the first case half 32 and the second case half 33. In addition, the case connecting fastening boss 22 is formed so that the first case half 32 and the second case half 33 are connected to each other by the case connecting bolt 23. Besides, the stud bolt fastening boss is formed so that internal combustion engine component parts 31 and 34 inclusive of the cylinder head 35 are connected to the crankcase 31 by the stud bolt 37. Further, the fastening surface is formed with the arm portion mounting boss 65 having the threaded hole 65e corresponding to the insertion hole 63d formed in the fastening arm portion 63. In addition, the arm portion mounting boss 65 is provided between the case connecting fastening boss 22 and the stud bolt fastening boss 24, closely to the case connecting fastening bolt 22 and the stud bolt fastening boss 24. This configuration ensures that the rigidity of the arm portion mounting boss 65 can be effectively enhanced by utilizing the existing case connecting fastening boss 22 and stud bolt fastening boss 24. Consequently, vibration of the piston cooling oil jetting device 60 is restrained, and oil jetting accuracy is enhanced.

[0029] In claim 9, the oil passage 56 in the crankcase 31 communicates with the oil pump 50. In addition, the oil discharged from the oil pump 50 is supplied to the main body portion 61 of the piston cooling oil jetting device 60 on the most upstream side which is on the upstream side of the position of branching to other passages. This ensures that the oil at a high pressure flows into the piston cooling oil jetting device 60. Therefore, the oil jetted from the nozzle portion 62 can reach the bottom surface of the piston 45 at a high speed. Consequently, a required part can be cooled with high accuracy and efficiently.

[0030] In claim 10, the cylinder bore 44 is so provided that the cylinder axis G is located in a plane orthogonal to a crank axis C, with an offset to either one of an upper side and a lower side with reference to the crank axis C. In addition, the piston cooling oil jetting device 60 is disposed on the offset side of the cylinder bore 44. This enables the piston cooling oil jetting device 60 to be disposed on the offset side of the cylinder bore 44. Therefore, the space for disposing the piston cooling oil jetting device 60 is enlarged. Consequently, interference of the piston cooling oil jetting device 60 with the connecting rod 47 and a crank web is avoided effectively.

[0031] In claim 11, the nozzle portion 62 and the piston 45 overlap each other in the direction of the cylinder axis G when the piston 45 is in the bottom dead center. In addition, the piston 45 is formed with the relief recess 45a for preventing interference thereof with the nozzle portion 62 in the overlapping position whereby the nozzle portion 62 can be disposed in the vicinity of the piston 45. Accordingly, the oil jetted from the oil jet port 62a of the nozzle portion 62 can reach a required part of the bottom surface of the piston 45 accurately. Consequently, the piston can be cooled efficiently.

[0032] Further features and advantages of the present invention will become apparent from the following detailed description, provided merely by way of non-limiting examples, with reference to the annexed drawings wherein:

Fig. 1 is a left side view of a motor scooter type motorcycle 1 provided with a mounting structure for a piston cooling oil jetting device 60 according to the present invention;

Fig. 2 is an illustration of an oil supply system for an overhead valve single-cylinder internal combustion engine 30 provided with the mounting structure for the piston cooing oil jetting device 60;

Fig. 3 is a longitudinal plan view of the overhead valve single-cylinder internal combustion engine 30 provided with the mounting structure for the piston cooling oil jetting device 60;

Fig. 4 is a longitudinal plan view, with a major portion enlarged, of the mounting structure of the piston cooling oil jetting device 60;

Fig. 5 is a longitudinal elevation of the overhead valve single-cylinder internal combustion engine 30 provided with the mounting structure for the piston cooling oil jetting device 60;

Fig. 6 is a sectional view of a cylinder block 34 taken along a plane set along a mating surface of a right crankcase 33 fitted with the piston cooling oil jetting device 60;

Fig. 7 is a sectional view showing a state where the piston cooling oil jetting device 60 is detached from the assembly of Fig. 6;

Fig. 8 is a front end view of the right crankcase 33 as viewed along the direction from the front side toward the rear side of a vehicle body, wherein the part indicated by broken lines 45 and 58 is a view as seen through a piston 45 and an oil groove 58;

Fig. 9 is a sectional view of a cylinder block 34, a cylinder head 35 and a head cover 36, taken along a plane passing through left and right two stud bolts 37a and 37b of the cylinder block 34; and

Fig. 10 is a sectional view of the right crankcase 33 taken along a plane extending from the front side toward the rear side of the vehicle body.



[0033] Now, an embodiment of a mounting structure for a piston cooling oil jetting device in an internal combustion engine according to the present invention as illustrated in Figs. 1 to 10 will be described below.

[0034] In a motor scooter type motorcycle 1 illustrated in Fig. 1, a vehicle body front portion 3 and a vehicle body rear portion 4 of a vehicle body 2 are connected to each other through a floor portion 5. A down tube 7 extends downward from a head pipe 6 of the vehicle body front portion 3. Front ends of a pair of left and right main pipes 8 are integrally connected respectively to both left and right sides of a lower end of the down tube 7. The main pipes 8 extend rearward while spreading to both left and right sides. Each of the main pipes 8 is curved obliquely toward a rear upper side, at a predetermined portion thereof. Both front ends of a side rail 9 curved in a U-shape in plan view are integrally connected to both rear ends of the main pipes 8, respectively. The angle of the side rail 9 relative to a horizontal plane is reduced at required portions of the side rail 9.

[0035] Besides, in the vehicle body rear portion 4, a seat 10 is disposed above the side rail 9. In the vehicle body front portion 3, a steering shaft (not shown) is fitted in the head pipe 6 so that it can be turned to the right and the left (clockwise and counterclockwise). A steering handlebar 11 is integrally attached to the steering shaft. A front fork 12 is integrally connected to the lower end of the steering shaft, and a front wheel 13 is rotatably supported on lower ends of the front fork 12.

[0036] Further, brackets 15 are integrally mounted to the curved portions of the main pipes 8. Hanger brackets 21 provided at lower portions of a power unit 20 are rotatably connected to the brackets 15 through links 16 so as to be swingable upward and downward.

[0037] Furthermore, the power unit 20 mounted on the motor scooter type motorcycle 1 in the state of being directed in the longitudinal vehicle direction includes a water-cooed overhead valve single-cylinder internal combustion engine 30 oriented forward, and a belt-type continuously variable transmission 80 directed rearward. Members constituting an outer shell structure of part of the overhead valve single-cylinder internal combustion engine 30 and the belt-type continuously variable transmission 80 include a cylinder block 34, a cylinder head 35, and a cylinder head cover 36, which are sequentially stacked on a crankcase 31, as shown in Figs. 2 and 9. The crankcase 31 includes left and right crankcases 32, 33 into which the crankcase 31 is bisected in a plane which contains the center line of a cylinder bore (described later) and which is orthogonal to the center line of a crankshaft 39 directed in the left-right width direction of the vehicle body. The crankcase 31, the cylinder block 34, and the cylinder head 35 are integrally assembled by stud bolts 37 which extend from the cylinder head 35, penetrate the cylinder block 34, and are put into screw engagement with the crankcase 31. The cylinder head cover 36 is integrally connected to the cylinder head 35 by a bolt 38. The crankcase 31 is formed in an integral form by coupling the left and right crankcases 32 and 33 to each other by a plurality of bolts 23 inclusive of bolts 23 (see Fig. 6).

[0038] In addition, left and right crankshafts 40 and 41, which are rotatably borne on the left crankcase 32 and the right crankcase 33 through bearings 43, respectively, are integrally coupled with each other by fitting a crank pin 42. Moreover, a piston pin 46 of a piston 45 slidably fitted in a cylinder bore 44 of the cylinder block 34 and the crank pin 42 of the crankshaft 39 are mutually connected through both end portions of a connecting rod 47. The crankshaft 39 is driven to rotate in conjunction with front-rear reciprocation of the piston 45 fitted in the cylinder bore 44 that is directed in a substantially horizontal direction.

[0039] Besides, as shown in Fig. 2, the belt-type continuously variable transmission 80 is disposed in the left crankcase 32. A drive pulley 82 is provided on the left crankshaft 40. An ACG starter 48 is provided on the right crankshaft 41 protruding rightward beyond the right crankcase 33.

[0040] Further, as shown in Fig. 2, an oil pump 50 driven by an oil pump driven gear 52 meshing with an oil pump driving gear 51, which is integral with the right crankshaft 41, is disposed inside the right crankcase 33 of the crankcase 31. An oil present in an oil pan 54 located below a crank chamber 49 is filtered by an oil strainer screen 55, before being sucked into the oil pump 50.

[0041] A valve train 76 for driving (opening and closing) suction and exhaust valves provided in the cylinder head 35 is disposed in a space defined by the cylinder head 35 and the cylinder head cover 36. An endless chain 74 is spanningly arranged between and wrapped around a drive sprocket 72 which is provided integrally with the right crankshaft 41, and a driven sprocket 73 which is integral with a rotary shaft 71 of the valve train 76. When the overhead valve single-cylinder internal combustion engine 30 is put into an operative state and then the crankshaft 39 rotates, the valve train 76 is put into an operative state through a transmission system including the drive sprocket 72, the driven sprocket 73, and the endless chain 74. The suction and exhaust valves (not shown) are opened and closed at required timings correspondingly to the reciprocation of the piston 45. As a result, intake gas is supplied into the cylinder bore 44, and the overhead valve single-cylinder internal combustion engine 30 is put into an operative state.

[0042] In addition, the left crankcase 32 of the crankcase 31 extends toward the vehicle body rear side, as a principal outer shell structure of the belt-type continuously variable transmission 80 that is shown in Fig. 1. A continuously variable transmission cover 81 is integrally mounted to the left side of the left crankcase 32. In the inside space of the belt-type continuously variable transmission 80 that is defined by the left crankcase 32 and the continuously variable transmission cover 81, a drive pulley 82 of the belt-type continuously variable transmission 80 is provided on the left crankshaft 40. On the other hand, a driven pulley 83 (see Fig. 1) is provided at a position on the vehicle body rear side. An endless V-belt 84 is spanningly arranged and wrapped around the drive pulley 82 and the driven pulley 83. The driven pulley 83 is connected to a rear wheel 14 through a speed reducer 85. When the rotating speed of the crankshaft 39 of the overhead valve single-cylinder internal combustion engine 30 increases, the gear ratio of the belt-type continuously variable transmission 80 is automatically changed in conjunction with the increase in rotating speed. As a result, the rotating speed of the rear wheel 14 is accelerated.

[0043] Now, an oil supply system will be described below.

[0044] In Fig. 2, an oil pump driving gear 51 is integrally mounted to the right crankshaft 41 at a position on the right-hand side of the drive sprocket 72 that drives the valve train 76. An oil pump driven gear 52 of the oil pump 50 meshes with this oil pump driving gear 51. A rotor 53 is integrally connected to this oil pump driven gear 52. When the overhead valve single-cylinder internal combustion engine 30 is put into an operative state, the oil pump 50 is driven to rotate. This results in that the oil in the oil pan 54 is filtered through the oil strainer screen 55, before being sucked into the oil pump 50. The oil pressurized in the oil pump 50 passes through an oil passage 56, to reach a mating surface between the right crankcase 33 and the cylinder block 34.

[0045] Fig. 8, which is a view from the front side of the vehicle body, shows the right crankcase 33. An end surface of the right crankcase 33 on the vehicle body front side is formed with an aperture of the oil passage 56, a first stud bolt insertion hole 25a and a second stud bolt insertion hole 25b. In addition, the left crankcase 32 is formed with a stud bolt insertion hole (not shown) in a positional relationship similar to that in the right crankcase 33. The stud bolts 37 that penetrate the cylinder head 35 and the cylinder block 34 from the front side toward the rear side are put into screw engagement with and fastened to the left and right crankcases 32 and 33.

[0046] A base end surface of the cylinder block 34 is formed with a curved groove 58 indicated by broken lines in Fig. 8. One end 58a of this groove 58 communicates with the oil passage 56. As this oil groove 58 extends upward, it bypasses the first stud bolt insertion hole 25a on the left side (in the drawing, on the right side) of the latter and then communicates with a crank bearing oil passage 57. The other end 58b of the oil groove 58 communicates with the second stud bolt insertion hole 25b.

[0047] Furthermore, a mounting structure for a main body portion 61 of the piston cooling oil jetting device 60 will be described.

[0048] At an inside surface of the right crankcase 33 of the crankcase 31 in the overhead valve single-cylinder internal combustion engine 30, an arm portion mounting boss 65 is provided in the state of projecting toward a cylinder axis G, as shown in Fig. 4. A fastening surface 65a of the arm portion mounting boss 65 is formed in a shape along a plane that is orthogonal to a crank axis C and contains the cylinder axis G. A main body portion mounting surface 65b parallel to the fastening surface 65a is formed at a position on the right side of the fastening surface 65a, with a predetermined interval therebetween. In addition, a contact surface portion 65c is formed which is perpendicular to the fastening surface 65a and the main body portion mounting surface 65b. A hole 65d is formed to extend rightward from the fastening surface 65a. The hole 65d is provided with a threaded hole 65e.

[0049] Fig. 4 shows a fastening arm portion 63 which has a deformed Z-shape. An arm-portion-side one part 63a, which is one part of the fastening arm portion 63 and is located in a central position of the fastening arm portion 63, is formed so that it can make secure contact with the contact surface portion 65c of the arm portion mounting boss 65. An arm-portion-side one end part 63b, which is one end of the fastening arm portion 63, is formed so that it can make secure contact with the fastening surface 65a of the arm portion mounting boss 65. In addition, another end part 63c, which is the other end of the fastening arm portion 63, is formed so that it can make secure contact with the main body portion mounting surface 65b. The arm-portion-side one end part 63b of the fastening arm portion 63 is formed with an insertion hole 63d through which a shaft portion of a screw engagement member 64 can pass. The main body portion 61 penetrates the other end part 63c of the fastening arm portion 63. The main body portion 61 is integrally attached to the other end part 63c by brazing or the like. An O-ring 61c is fitted on a near-tip part of the main body portion 61.

[0050] A nozzle portion 62 is projectingly provided at a base end part of the main body portion 61. In the state where the main body portion 61 is mounted to the arm portion mounting boss 65, as shown in Fig. 4, the nozzle portion 62 communicates with the oil passage 56 via an oil communication passage 61a and an opening 61b in the main body portion 61. In this state, the oil discharged from the oil pump 50 is sent to the nozzle portion 62 via the oil passage 56, the opening 61b, and the oil communication passage 61a. Then, the oil is jetted from an oil jet port 62a at the tip of the nozzle portion 62 toward a lower surface central portion 45b of the piston 45 as shown in Fig. 6, specifically, as indicated by an oil jet path F.

[0051] The piston cooling oil jetting device 60 is configured as above-described. This configuration ensures the following. In a state where the main body portion 61 is fitted in a jetting device main body portion mounting hole 65f in the arm portion mounting boss 65, the one part 63a of the fastening arm portion 63 is set in contact with the contact surface portion 65c of the arm portion mounting boss 65, and the screw engagement member 64 passing through the insertion hole 63d in the fastening arm portion 63 is in screw engagement with the threaded hole 65e in the arm portion mounting boss 65, the fastening arm portion 63 is prevented from rotating relative to the arm portion mounting boss 65, even when a large torque is exerted onto the arm-portion-side one end part 63b of the fastening arm portion 63 by rotating the screw engagement member 64. This prevention is achieved by not only a frictional force between the fastening surface 65a of the arm portion mounting boss 65 and the arm-portion-side one end part 63b of the fastening arm portion 63 but also positional regulation owing to the contact of the contact surface portion 65c of the arm portion mounting boss 65 with the one part 63a of the fastening arm portion 63. In addition, the main body portion 61 is integrally connected to the fastening arm portion 63. As a result, there is no risk of rotation of the main body portion 61. Further, the main body portion 61 is mounted in a stable manner, without falling in relation to the jetting device main body portion mounting hole 65f. Therefore, a sealing property provided between the main body portion 61 and the jetting device main body portion mounting hole 65f by the O-ring 61c can be maintained uniformly. In addition, the oil jetted from the oil jet port 62a of the nozzle portion 62 is accurately jetted to a required part, so that the oil is effectively supplied to the lower surface central portion 45b of the piston 45. Consequently, a top portion of the piston 45 where heat load is high can be cooled effectively.

[0052] As shown in Fig. 8, a residual portion of the oil sent through the oil passage 56 to the piston cooling oil jetting device 60 flows through the one end part 58a and the oil groove 58, and flows via the crank bearing oil passage 57 into the crank pin 42 as shown in Fig. 2. Then, the oil is jetted via a space between the crank pin 42 and a large diameter end of the connecting rod 47 into the inside of the cylinder bore 44, to lubricate a contact part between the cylinder 44 and the piston pin 46.

[0053] Furthermore, as shown in Fig. 2, the residual portion of the oil flowing through the oil groove 58 reaches a second stud bolt penetration hole 57b, and is supplied to the valve train 76.

[0054] As shown in Fig. 4, the mounting structure for the piston cooling oil jetting device 60 fastened and fixed to the crankcase 31 by the screw engagement member 64 includes: the main body portion 61 having the oil channel communicating with the oil passage 56 provided in the crankcase 31; the nozzle portion 62 which extends from the main body portion 61 toward the piston 45 in the cylinder bore 44 and which has the oil jet port 62a; and the fastening arm portion 63 which is provided to project from the main body portion 61 and which is formed with the insertion hole 63d permitting the screw engagement member 64 to be inserted and passed therethrough. The mounting structure for the piston cooling oil jetting device 60 fastened and fixed to the crankcase 31 includes the screw engagement member 64.

[0055] Of the arm portion mounting boss 65 of the crankcase 31, the fastening surface 65a and the main body portion mounting surface 65b (to which the main body portion 61 is mounted) are formed on planes different in height with respect to the axial direction of the screw engagement member 64 taken as a height direction. The fastening surface 65a and the main body portion mounting surface 65b are connected to each other through the contact surface portion 65c extending along the axial direction of the screw engagement member 64. The fastening arm portion 63 is formed along the contact surface portion 65c of the arm portion mounting boss 65. In a condition where the piston cooling oil jetting device 60 is fixed to the crankcase 31, at least the one part 63a of the fastening arm portion 63 is put in contact with the contact surface portion 65c, and the one end part 63b of the fastening arm portion 63 is fastened to the fastening surface 65a. Therefore, at the time of mounting the piston cooing oil jetting device 60 to the crankcase 31, the contact of the one part 63a of the fastening arm portion 63 with the contact surface portion 65c of the arm portion mounting boss 65 can inhibit the main body portion 61 from rotating together with the screw engagement member 64 attendantly on the rotation of the screw engagement member 64. This enables favorable positioning of the piston cooling oil jetting device 60. Consequently, the oil jetted from the nozzle portion 62 of the piston cooling oil jetting device 60 can be made to accurately reach a required part of the lower surface of the piston 45.

[0056] The contact surface portion 65c is formed to have a plane surface substantially parallel to the axis of the screw engagement member 64. The one part 63a, formed in a plate-like shape, of the fastening arm portion 63 makes contact with the plane surface. Therefore, the one part 63a can be enlarged. Accordingly, a further higher positioning accuracy is attained.

[0057] The other end part 63c of the fastening arm portion 63 is put in pressure contact with the main body portion mounting surface 65b. This makes it possible to obtain a further higher positioning accuracy in positioning the piston cooling oil jetting device 60.

[0058] Referring to Fig. 8 as well, the crankcase 31 is so configured that it can be divided (separated) into the first case half 32 and the second case half 33. In addition, the fastening surface 65a is formed on the same plane with the parting face of the crankcase 31. Therefore, screw thread cutting for fastening of the screw engagement member can be carried out easily. This promises enhanced productivity. Further, a working space for fastening the screw engagement member by use of a tool can be secured easily, so that a fastening work can be carried out easily. Consequently, a further enhanced productivity is realized.

[0059] The parting face of the crankcase 31 is located on the cylinder axis G. The fastening surface 65a is formed on the same plane surface as the parting face of either one crankcase half of the first case half 32 and the second case half 33. The main body portion mounting surface 65b is formed on an inside wall surface which is part of the one crankcase half and which is spaced from the cylinder axis. This configuration ensures that interference of the nozzle portion 62 with the piston 45 moving inside the crankcase 31 or with the connecting rod 47 connected to the piston 45 can be obviated easily.

[0060] Referring to Figs. 5 and 7 as well, the crankcase 31 is configured to be divisible into the first case half 32 and the second case half 33. Case connecting fastening bosses 22 are formed so that the first case half 32 and the second case half 33 are connected to each other by case connecting bolts 23. The fastening surface 65a is formed with the arm portion mounting boss 65 having the fastening hole 65d corresponding to the insertion hole 63d formed in the fastening arm portion 63. The arm portion mounting boss 65 is provided close to the case connecting fastening boss 22. This configuration ensures that the rigidity of the arm portion mounting boss 65 can be effectively enhanced by utilizing the existing case connecting fastening boss 22. Consequently, vibration of the piston cooling oil jetting device 60 can be restrained, and oil jetting accuracy can be enhanced.

[0061] In addition, stud bolt fastening bosses 24 are formed so that internal combustion engine component parts 31 and 34 inclusive of the cylinder head 35 are connected to the crankcase 31 by stud bolts 37. The fastening surface 65a is formed with the arm portion mounting boss 65 having the fastening hole 65d corresponding to the insertion hole 63d formed in the fastening arm portion 63. The arm portion mounting boss 65 is provided close to the stud bolt fastening boss 24. Therefore, the rigidity of the arm portion mounting boss 65 can be effectively enhanced by utilizing the existing stud bolt fastening bosses 24. This makes it possible to restrain vibrations of the piston cooling oil jetting device 60, and to enhance oil jetting accuracy.

[0062] Furthermore, the crankcase 31 is configured to be divisible into the first case half 32 and the second case half 33. The case connecting fastening bosses 22 are formed so that the first case half 32 and the second case half 33 are connected to each other by the case connecting bolts 23. The stud bolt fastening bosses 24 are formed so that internal combustion engine component parts 31 and 34 inclusive of the cylinder head 35 are connected to the crankcase 31 by the stud bolts 37. The fastening surface is formed with the arm portion mounting boss 65 having the threaded hole 65e corresponding to the insertion hole 63d formed in the fastening arm portion 63. The arm portion mounting boss 65 is provided between the case connecting fastening boss 22 and the stud bolt fastening boss 24, closely to the case connecting fastening boss 22 and the stud bolt fastening boss 24. This configuration ensures that the rigidity of the arm portion mounting boss 65 can be effectively enhanced by utilizing the existing case connecting fastening bosses 22 and stud bolt fastening bosses 24. Consequently, vibration of the piston cooling oil jetting device 60 is restrained, and oil jetting accuracy is enhanced.

[0063] Referring to Fig. 2, the oil passage 56 in the crankcase 31 communicates with the oil pump 50. In addition, the oil discharged from the oil pump 50 is supplied to the main body portion 61 of the piston cooling oil jetting device 60 on a most upstream side, without branching into other oil passages 57 and 57b. This ensures that the oil at a high pressure flows into the piston cooling oil jetting device 60. Therefore, the oil jetted from the nozzle portion 62 can reach the bottom surface of the piston 45 at a high speed. Consequently, a required part can be cooled with high accuracy and efficiently.

[0064] Referring to Fig. 6, the cylinder bore 44 is so provided that the cylinder axis G is located in a plane orthogonal to a crank axis C, with an offset to either one of an upper side and a lower side (in Fig. 6, to the lower side) with reference to the crank axis C. The piston cooling oil jetting device 60 is disposed on the offset side of the cylinder bore 44. This enables the piston cooling oil jetting device 60 to be disposed on the offset side of the cylinder bore 44. Therefore, the space for disposing the piston cooling oil jetting device 60 is enlarged. Consequently, interference of the piston cooling oil jetting device 60 with the connecting rod 47 and a crank web is avoided effectively.

[0065] Referring to Fig. 10, the lowermost end of the piston is located below (in Fig. 10, on the rear side of) an uppermost end part of the nozzle portion 62 when the piston is at the bottom dead center. This configuration ensures that the nozzle portion 62 and the piston 45 are disposed in such a positional relationship that they overlap each other in the direction of the cylinder axis G when the piston 45 is in the bottom dead center. In addition, the piston 45 is formed with a relief recess 45a for preventing interference thereof with the nozzle portion 62 in the overlapping position. Specifically, the piston is so formed that its lower end is partly cut out so that the nozzle portion can be disposed close to the piston. Accordingly, the oil jetted from the oil jet port 62a of the nozzle portion 62 can reach a required part of the bottom surface of the piston 45 accurately. Consequently, the piston can be cooled efficiently.

[0066] Incidentally, while an example in which the piston cooling oil jetting device is applied to an internal combustion engine of a motor scooter type motorcycle has been shown in the embodiment of the present invention, this is not restrictive. The piston cooling oil jetting device is applicable also to other motorcycles and saddle type vehicles inclusive of three-wheel automobiles and all-terrain vehicles.

Main reference symbols:



[0067] 
22
Case connecting fastening boss
23
Case connecting bolt
24
Stud bolt fastening boss
31
Crankcase
32
Left crankcase
33
Right crankcase
34
Cylinder block
35
Cylinder head
37
Stud bolt
37a
First stud bolt
44
Cylinder bore
45
Piston
45a
Relief recess
50
Oil pump
56
Oil passage
60
Piston cooling oil jetting device
61
Main body portion
62
Nozzle portion
62a
Oil jet port
63
Fastening arm portion
63a
One part
63b
One end part
63c
Other end part
63d
Insertion hole
64
Screw engagement member
65
Arm portion mounting boss
65a
Fastening surface
65b
Main body portion mounting surface
65c
Contact surface portion
65e
Threaded hole
65f
Jetting device main body portion mounting hole
G
Cylinder axis
C
Crank axis.



Claims

1. A mounting structure for a piston cooling oil jetting device, including
a piston cooling oil jetting device (60) fastened and fixed to a crankcase (31) by a screw engagement member (64), the piston cooling oil jetting device (60) comprising:

a main body portion (61) having an oil channel communicating with an oil passage (56) provided in the crankcase (31);

a nozzle portion (62) extending from the main body portion (61) toward a piston (45) in a cylinder bore (44), the nozzle portion (62) having an oil jet port (62a); and

a fastening arm portion (63) provided to project from the main body portion (61), the fastening arm portion (63) formed therein with an insertion hole (63d) through which the screw engagement member (64) is inserted and passed,

wherein the crankcase (31) is provided with an arm portion mounting boss (65) to which the screw engagement member (64) is fastened, and a main body portion mounting hole (65f) into which the main body portion (61) is mounted,

a fastening surface (65a) of the arm portion mounting boss (65) and a main body portion mounting surface (65b) of the main body mounting hole (65f) are formed on planes different in height with respect to an axial direction of the screw engagement member (64) taken as a height direction, and

the fastening surface (65a) and the main body portion mounting surface (65b) are connected to each other through a contact surface portion (65c) extending along the axial direction of the screw engagement member (64); and

wherein the fastening arm portion (63) is formed along the contact surface portion (65c) of the arm portion mounting boss (65),

at least one part (63a) of the fastening arm portion (63) is in contact with the contact surface portion (65c) in a state where the piston cooling oil jetting device (60) is fixed to the crankcase (31), and

one end part (63b) of the fastening arm portion (63) is fastened to the fastening surface (65a).


 
2. The mounting structure for the piston cooling oil jetting device according to claim 1, wherein the contact surface portion (65c) is formed to have a plane surface substantially parallel to an axis of the screw engagement member (64), and the one part (63a), formed in a plate-like shape, of the fastening arm portion (63) makes contact with the plane surface.
 
3. The mounting structure for the piston cooling oil jetting device according to claim 2, wherein another end part (63c) of the fastening arm portion (63) is set in pressure contact with the main body portion mounting surface (65b).
 
4. The mounting structure for the piston cooling oil jetting device according to any of claims 1 to 3, wherein the crankcase (31) is configured to be divisible into a first case half (32) and a second case half (33), and the fastening surface (65a) is formed on a same plane with a parting face of the crankcase (31).
 
5. The mounting structure for the piston cooling oil jetting device according to claim 4, wherein the parting face of the crankcase (31) is provided on a cylinder axis (G), the fastening surface (65a) is formed on a same plane with the parting face of either one crankcase half of the first case half (32) and the second case half (33), and the main body portion mounting surface (65b) is formed on an inside wall surface which is part of the one crankcase half and which is spaced from the cylinder axis.
 
6. The mounting structure for the piston cooling oil jetting device according to any of claims 1 to 4, wherein the crankcase (31) is configured to be divisible into a first case half (32) and a second case half (33), and a case connecting fastening boss (22) is formed so that the first case half (32) and the second case half (33) are connected to each other by a case connecting bolt (23); and wherein the fastening surface (65a) is formed with the arm portion mounting boss (65) having a fastening hole (65d) corresponding to the insertion hole (63d) formed in the fastening arm portion (63), and the arm portion mounting boss (65) is provided close to the case connecting fastening boss (22).
 
7. The mounting structure for the piston cooling oil jetting device according to any of claims 1 to 6, wherein a stud bolt fastening boss (24) is formed so that internal combustion engine component parts (31, 34) inclusive of a cylinder head (35) are connected to the crankcase (31) by a stud bolt (37); and wherein the fastening surface (65a) is formed with the arm portion mounting boss (65) having a fastening hole (65d) corresponding to the insertion hole (63d) formed in the fastening arm portion (63), and the arm portion mounting boss (65) is provided close to the stud bolt fastening boss (24).
 
8. The mounting structure for the piston cooling oil jetting device according to any of claims 1 to 7, wherein the crankcase (31) is configured to be divisible into a first case half (32) and a second case half (33), a case connecting fastening boss (22) is formed so that the first case half (32) and the second case half (33) are connected to each other by a case connecting bolt (23), a stud bolt fastening boss (24) is formed so that internal combustion engine component parts (31, 34) inclusive of a cylinder head (35) are connected to the crankcase (31) by a stud bolt (37), the fastening surface is formed with the arm portion mounting boss (65) having a threaded hole (65e) corresponding to the insertion hole (63d) formed in the fastening arm portion (63), and the arm portion mounting boss (65) is provided between the case connecting fastening boss (22) and the stud bolt fastening boss (24), closely to the case connecting fastening boss (22) and the stud bolt fastening boss (24).
 
9. The mounting structure for the piston cooling oil jetting device according to any of claims 1 to 8, wherein the oil passage (56) in the crankcase (31) communicates with an oil pump (50), and an oil discharged from the oil pump (50) is supplied to the main body portion (61) of the piston cooling oil jetting device (60) on a most upstream side which is on an upstream side of a position of branching to other passages.
 
10. The mounting structure for the piston cooling oil jetting device according to any of claims 1 to 9, wherein the cylinder bore (44) is so provided that the cylinder axis (G) is located in a plane orthogonal to a crank axis (C), with an offset to either one of an upper side and a lower side with reference to the crank axis (C), and the piston cooling oil jetting device (60) is disposed on the offset side of the cylinder bore (44).
 
11. The mounting structure for the piston cooling oil jetting device according to any of claims 1 to 10, wherein the nozzle portion (62) and the piston (45) overlap each other in the direction of the cylinder axis (G) when the piston (45) is in a bottom dead center, and the piston (45) is formed with a relief recess (45a) for preventing interference thereof with the nozzle portion (62) in the overlapping position.
 




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Search report




Cited references

REFERENCES CITED IN THE DESCRIPTION



This list of references cited by the applicant is for the reader's convenience only. It does not form part of the European patent document. Even though great care has been taken in compiling the references, errors or omissions cannot be excluded and the EPO disclaims all liability in this regard.

Patent documents cited in the description