Engine and method for producing engine

Abstract

To improve assembly workability of an engine.SOLUTION: In an engine (1), a split face (LD) of a crank case (11) is offset to one of right and left sides from a stud bolt (71) between cylinders. A main shaft (31) penetrates a first crank case (11R), which is one of the right and left crank cases with a narrower width, and attached to a second crank case (11L) at a position where the main shaft does not penetrate the second crank case (11L), the second crank case being the other one of the right and left crank cases with a larger width. When a predefined component near the main shaft (31) including the first crank case (11R) is not attached, the first crank case (11R) is movable to a position where it is inserted into the main shaft (31) and fixed to the second crank case (11L), with the main shaft (31) attached to the second crank case (11L).SELECTED DRAWING: Figure 6

Description

[Technical Field]

[0001] The present invention relates to an engine and a method for manufacturing an engine. [Background technology]

[0002] There is known an engine in which a left-right split crankcase, a cylinder block, and a cylinder head are fastened together with stud bolts. One example of such an engine is a parallel twin-cylinder configuration in which the split plane of the crankcase is offset toward the transmission located on the left side of the crankcase (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2000-043593 Summary of the Invention [Problem to be solved by the invention]

[0004] In the case of a parallel twin-cylinder engine, it is desirable to position the stud bolts between the cylinders at equal distances from the center of each cylinder bore, but the dividing surface of the crankcase is positioned at equal distances from the center of each cylinder, which may make it impossible to position the stud bolts in the desired locations. In the engine described in Patent Document 1, the dividing surface of the crankcase is offset to one of the left and right sides of the crankcase, which makes it easier to arrange the stud bolts at equal positions from the center of each cylinder. However, since either the left or right crankcase becomes wider, the workability associated with moving the wide crankcase decreases, and there is a risk that the workability may decrease, for example, when passing the crankshaft through the wide crankcase. The present invention has been made in view of the above circumstances, and has as its object to improve the workability of assembling an engine. [Means for solving the problem]

[0005] The engine has a left-right split crankcase, a parallel twin-cylinder cylinder block, and a cylinder head fastened with stud bolts, and is provided with a main shaft and a counter shaft that form at least part of a transmission inside the crankcase, the split surface of the crankcase being offset to the left or right from the stud bolts between the cylinders, the main shaft is attached to the second crankcase at a position where it passes through a narrow first crankcase on one side and does not pass through a wider second crankcase on the other side, and when certain parts around the main shaft, including the first crankcase, are not attached, the engine is capable of moving the first crankcase, with the main shaft attached to the second crankcase, to a position where it can be inserted and fixed to the second crankcase.

[0006] The present invention also provides a manufacturing method for an engine in which a left-right split crankcase, a parallel twin-cylinder cylinder block, and a cylinder head are fastened together with stud bolts, and a main shaft and a counter shaft that form at least part of a transmission are provided within the crankcase, where the dividing surface of the crankcase is offset to the left or right from the stud bolts between the cylinders, and the main shaft is a member that passes through a narrow first crankcase on one side of the left or right, but is attached to the second crankcase at a position that does not pass through a wide second crankcase on the other side of the left or right, and in which the main shaft is attached to the second crankcase during engine assembly, and the first crankcase is joined to the second crankcase by inserting the main shaft into it. [Effects of the Invention]

[0007] According to the present invention, the efficiency of engine assembly can be improved. [Brief explanation of the drawings]

[0008] [Figure 1] 1 is a side cross-sectional view of an engine according to an embodiment of the present invention. [Figure 2]1 is a cross-sectional view of an engine taken along a plane passing through a cylinder section, a crankshaft, a main shaft, and a counter shaft. [Figure 3] FIG. 2 is a view showing an end face of the cylinder block. [Figure 4] FIG. 4 is a view showing the left crankcase from the dividing plane side. [Figure 5] FIG. 4 is a view showing the right crankcase from the dividing plane side. [Figure 6] 10 is a diagram showing the communication passage together with the surrounding configuration in a state where the left and right crankcases are fastened and fixed together. FIG. [Figure 7] 10A and 10B are diagrams illustrating the assembly of the main shaft and the left and right crankcases. [Figure 8] FIG. 2 is a cross-sectional view showing the pump shaft together with the surrounding structure. [Figure 9] FIG. 10 is a diagram illustrating the assembly of the pump shaft and the left and right crankcases. DETAILED DESCRIPTION OF THE INVENTION

[0009] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a side cross-sectional view of an engine 1 according to an embodiment of the present invention. Engine 1 is a water-cooled engine mounted on a motorcycle, and can also be called an internal combustion engine and a power unit. Engine 1 includes a crankcase 11 that rotatably supports crankshaft 10, and a cylinder section 12F that forms front cylinders (also called a front bank) that extend forward and inclined forward from the top of crankcase 11. Cylinder section 12F includes a cylinder block 12a, a cylinder head 12b connected to the top surface of cylinder block 12a, and a head cover 12c that covers the top surface of cylinder head 12b.

[0010] A cylinder bore 15 is formed in the cylinder block 12a, and a piston 16 is provided in the cylinder bore 15. The piston 16 is connected to the crankshaft 10 via a connecting rod 17. The cylinder head 12b is formed with an intake port 18a and an exhaust port 18b, and is provided with an intake valve 19a and an exhaust valve 19b that open and close the ports 18a and 18b. A valve train 20 that drives the valves 19a and 19b is provided between the cylinder head 12b and the head cover 12c.

[0011] In this description, unless otherwise specified, directions such as front, rear, left, right, and up and down are directions based on the engine 1 and coincide with directions based on the motorcycle on which the engine 1 is mounted. In each drawing, the symbol FR indicates the front of the engine, the symbol UP indicates the top of the engine, and the symbol LH indicates the left of the engine.

[0012] The crankcase 11 is formed as a hollow case that is divided by a partition wall 11c into a sealed crank chamber 11a that houses the main parts of the crankshaft 10 (such as the crank web 10c) and a transmission chamber 11b that houses the transmission 21. The crankcase 11 of this embodiment is divided into left and right halves, and an oil pan 22 is formed integrally with the lower part of the crankcase 11. The oil pan 22 functions as an oil reservoir that stores oil that lubricates each part of the engine 1.

[0013] The crankshaft 10 is rotatably supported in the crankcase 11 along the left-right direction of the engine (corresponding to the vehicle width direction). The transmission chamber 11b is formed in the rear part of the crankcase 11 (rear of the sealed crankcase 11a). A main shaft 31 and a counter shaft 32, which are rotatably supported in the crankcase 11, are provided in the transmission chamber 11b.

[0014] Additionally, a balancer 25 and a balancer shaft 26 are disposed in the sealed crank chamber 11a to suppress primary vibration of the engine 1 caused by the piston 16 in the cylinder portion 12F. A cartridge-type oil filter 27 and an oil cooler 28 are disposed on the front lower left side of the crankcase 11.

[0015] FIG. 2 is a cross-sectional view of the engine 1 taken along a plane passing through the cylinder section 12F, the crankshaft 10, the main shaft 31, and the counter shaft 32. 2, the cylinder bores 15 are aligned in the left-right direction. A sealed crank chamber 11a of the crankcase 11 communicates with the cylinder bores 15. 1 and 2, gear groups 31a, 32a, etc. provided on main shaft 31 and counter shaft 32 form transmission 21 that can transmit the rotation of crankshaft 10 to counter shaft 32 at a plurality of gear ratios. Main shaft 31 and counter shaft 32 are arranged parallel to crankshaft 10. Counter shaft 32 functions as the output shaft of engine 1 and drives rear wheels, which are drive wheels, via a power transmission mechanism (for example, a chain transmission mechanism).

[0016] As shown in Fig. 1, a feed pump 41 is disposed below the crankcase 11, above the oil pan 22, to draw oil from the oil pan 22 through the oil strainer 23 and supply it to lubrication points of the engine 1. The feed pump 41 includes an inner rotor 41b and an outer rotor 41c that form a feed pump rotor 41r, and the inner rotor 41b rotates integrally with the pump shaft 42, thereby drawing oil from the oil pan 22 and discharging it to the lubrication points of the engine. The pump shaft 42 is disposed parallel to the crankshaft 10 and is rotatably supported by the crankcase 11. The feed pump 41 is an example of a lubricating oil pump, and the feed pump rotor 41r is an example of a pump rotor.

[0017] 2, the right ends of the crankshaft 10 and the main shaft 31 protrude to the right, which is one of the left and right outer sides, from the crankcase 11. A primary drive gear 35 is attached to the right end of the crankshaft 10. A primary driven gear 36 that meshes with the primary drive gear 35 and a clutch mechanism 51 that can interrupt power transmission between the primary driven gear 36 and the main shaft 31 are attached to the right end of the main shaft 31.

[0018] A clutch cover 2 that functions as a right crankcase cover that covers the right opening of the crankcase 11 is fastened to the right end of the crankcase 11. The crankcase 11 and the clutch cover 2 form a clutch chamber 11d that houses a clutch mechanism 51 on the right side of the sealed crank chamber 11a and the transmission chamber 11b. The clutch mechanism 51 is an example of an accessory chamber on the right side of the engine, and the clutch chamber 11d is an example of an accessory chamber on the right side of the engine.

[0019] The left end of the crankshaft 10 protrudes leftward from the crankcase 11. A generator 61 that generates electricity by the rotation of the crankshaft 10 is attached to this left end. A generator cover 3, which functions as a left crankcase cover that covers the left opening of the crankcase 11, is fastened and fixed to the left end of the crankcase 11. The crankcase 11 and the generator cover 3 form a generator chamber 11e that houses a generator 61 on the left side of the sealed crank chamber 11a and the transmission chamber 11b. The generator 61 is an example of an accessory on the left side of the engine, and the generator room 11e is an example of an accessory room on the left side of the engine.

[0020] 2, the symbol LC indicates a position that is equal to the center C of each cylinder bore of the parallel twin cylinders. The symbol LD indicates the position of the dividing plane between the left and right crankcases 11, and hereinafter, the dividing plane will be denoted by the symbol LD. 2, the dividing plane LD of the left and right crankcases 11 is located at a position offset by a value S to one side (the right side in this embodiment) from the equal position LC from the center C of each cylinder bore. The dividing plane LD is a plane extending along a vertical plane perpendicular to the axis of the crankshaft 10. The oil pan 22 is divided into left and right halves and is formed integrally with each of the left crankcase 11L and the right crankcase 11R.

[0021] FIG. 3 is a view showing an end face of the cylinder block 12a. In this engine 1, a cylinder block 12a and a cylinder head 12b of a cylinder section 12F are stacked on a crankcase 11, and these are fastened together by a plurality of stud bolts 71 (six for the cylinder section 12F in this configuration). The stud bolts 71 are inserted into bolt holes 72 provided around the cylinder bore 15. The bolt holes 72 are formed at the four corners around each cylinder bore 15, and four stud bolts 71 fasten the periphery of each cylinder bore 15. In addition, a common bolt hole 72 is formed between the cylinder bores 15 at the portion where the peripheries of the adjacent cylinder bores 15 overlap, and two stud bolts 71, one at the front and one at the rear, are inserted through the common bolt hole 72.

[0022] 3, the dividing plane LD between the left and right crankcases 11 is offset to one side from the position LC, so the stud bolts 71 between the cylinders can be provided at the position LC. This makes it easier to evenly fasten the crankcases 11, cylinder block 12a, and cylinder head 12b. The stud bolts 71 between the cylinders are fitted into the left crankcase 11L.

[0023] On one side in the arrangement direction of the cylinders, i.e., on the right side, there is formed a cam chain chamber 73. In the cam chain chamber 73, a cam chain that functions as a transmission member that transmits the rotation of the crankshaft 10 to the valve mechanism 20 is arranged. In this embodiment, cam chain chambers 73 are formed on the right side of the cylinder portion 12F, and a semi-cam gear train type valve train drive unit is provided that drives the cam chains arranged in each cam chain chamber 73 by reducing the rotation speed of the crankshaft 10. The valve train drive unit has a sprocket around which one end of the cam chain is wound, and a gear train that reduces the rotation speed of the crankshaft 10 and transmits it to the sprocket. The sprocket and gear train are arranged together on the right side of the crankcase 11 and housed in the clutch chamber 11d.

[0024] FIG. 4 is a view showing the left crankcase 11L from the dividing plane LD side. The left crankcase 11L is formed with a left main shaft hole 76L to which the left end of the main shaft 31 is fixed via a bearing 75L (see FIG. 2), a left counter shaft hole 78L to which the left end of the counter shaft 32 is fixed via a bearing 77L, and a left pump shaft hole 79L through which the pump shaft 42 is inserted. In addition, the left crankcase 11L is provided with an oil filter 27 and an oil cooler 28.

[0025] The sidewall 11LW of the left crankcase 11L also serves as a left partition wall separating the crankcase interior space from the generator chamber 11e. A left-side communication passage 80L that communicates in the left-right direction is formed in the area of ​​this sidewall 11LW that overlaps with the generator chamber 11e in the left-right direction. The left-side communication passage 80L has a through-hole 80La that penetrates in the left-right direction and an enclosing wall 80Lb that endlessly surrounds the periphery (front-to-back and top-to-bottom) of the through-hole 80La and extends in the left-right direction to the dividing plane LD.

[0026] FIG. 5 is a view showing the right crankcase 11R from the dividing plane LD side. The right crankcase 11R is formed with a right main shaft hole 76R to which the right side of the main shaft 31 is fixed via a bearing 75R (see FIG. 2), a right counter shaft hole 78R to which the right end of the counter shaft 32 is fixed via a bearing 77R, and a right pump shaft hole 79R through which the pump shaft 42 is inserted.

[0027] A side wall 11RW of the right crankcase 11R doubles as a right partition wall that separates the interior space of the crankcase 11 from the clutch chamber 11d. A right communication passage 80R that communicates in the left-right direction is formed in the area of ​​this side wall 11RW that overlaps with the clutch chamber 11d in the left-right direction. The right communication passage 80R has a through hole 80Ra that penetrates in the left-right direction and a surrounding wall 80Rb that endlessly surrounds the periphery (front-to-back and top-to-bottom) of the through hole 80Ra and extends in the left-to-right direction to the position of the dividing plane LD.

[0028] When the left and right crankcases 11 are fastened together, the end faces of the left and right surrounding walls 80Lb, 80Rb come into contact with each other, and the through holes 80La, 80Ra in each surrounding wall 80Lb, 80Rb form an independent communication passage 80 that connects the generator chamber 11e and the clutch chamber 11d, as shown in Fig. 6. In other words, the left communication passage 80L and the right communication passage 80R form an independent communication passage 80 in the crankcase 11 that connects the generator chamber 11e and the clutch chamber 11d, which are the left and right accessory chambers. A sealant is inserted between the left and right crankcases 11 as appropriate.

[0029] In this engine 1, oil in the generator chamber 11e and oil in the clutch chamber 11d are sucked by a first suction oil pump 91, which will be described later. In FIG. 7, the flow of oil in the clutch chamber 11d by the first suction oil pump 91 is indicated by arrow Yc, and the flow of oil in the generator chamber 11e is indicated by arrow Ya. As shown in FIG. 7, a suction port 80k connected to the first suction oil pump 91 is provided downstream of the communication passage 80, which is made up of the left communication passage 80L and the right communication passage 80R. The oil in the generator chamber 11e and the oil in the clutch chamber 11d can be sucked from this suction port 80k. This allows the oil in both the left and right accessory chambers to be sucked by a single oil pump 91.

[0030] Next, the structure relating to the assembly of the main shaft 31 and the left and right crankcases 11R, 11L will be described. 2, the main shaft 31 passes through the right crankcase 11R but does not pass through the left crankcase 11L. The main shaft 31 is fixed to the left crankcase 11L via left and right bearings 75L and 75R. When assembling the engine, as shown in Figure 7, the wide left crankcase 11L is placed on a workbench or the like in an orientation rotated 90 degrees, and the main shaft 31 is fixed to the left crankcase 11L. Then, the narrow right crankcase 11R is moved downward from above relative to the left crankcase 11L, thereby inserting the main shaft 31 into the right crankcase 11R, and moving the right crankcase 11R to a position where it will be joined to the left crankcase 11L. This procedure improves the ease of assembly of the engine 1, and in particular, the narrow right crankcase 11R is relatively light, making the crankcase movement procedure easier.

[0031] When assembling the main shaft 31 and the left and right crankcases 11R, 11L, certain parts around the main shaft 31 (such as the clutch mechanism 51) must be removed in advance so as not to interfere with the assembly work. Also, some parts cannot be installed after the crankcases 11L, 11R are fixed together. For example, parts related to the transmission 21 (such as the counter shaft 32 and gear groups 31a, 32a) must be installed in advance on the shafts 31, 32 and the crankcases 11L, 11R.

[0032] 7, parts that are attached to the shafts 31, 32 and the crankcases 11L, 11R in advance are indicated by solid lines, and parts that are to be removed are indicated by virtual lines (two-dot chain lines). However, when assembling the main shaft 31 and the left and right crankcases 11L, 11R, it is necessary to appropriately select which parts to remove and which parts to attach depending on the structure of the engine 1.

[0033] The orientation of each part when assembling the main shaft 31 and the left and right crankcases 11R, 11L does not have to be limited to the orientation shown in Fig. 7. The assembly work may be performed manually by a worker or by using an assembly device such as a robot arm.

[0034] FIG. 8 is a cross-sectional view showing the pump shaft 42 together with the surrounding structure. This engine 1 is equipped with a feed pump 41 that supplies oil from the oil pan 22 to lubricated parts of the engine 1, a first suction oil pump 91 that is a scavenging pump that sucks oil from the generator chamber 11e, and a second suction oil pump 92 that is a scavenging pump that sucks oil from the sealed crank chamber 11a. These pumps 41, 91, and 92 supply oil to lubricated parts (piston 16, valve train 20, transmission 21, clutch mechanism 51, etc.), and also quickly collect oil discharged from the lubricated parts into the oil pan 22.

[0035] As shown in Fig. 8, the feed pump 41, the first suction oil pump 91, and the second suction oil pump 92 are arranged on a common pump shaft 42. Explaining the pump structure in more detail, casings 41g, 91g, and 92g of the feed pump 41, the first suction oil pump 91, and the second suction oil pump 92 are respectively formed integrally with the left crankcase 11L. The casings 41g, 91g, and 92g are formed side by side in the left-right direction. Pump rotors 41r, 91r, and 92r of each pump 41 are respectively arranged in the casings 41g, 91g, and 92g, and the pump rotors 41r, 91r, and 92r are attached to the pump shaft 42 that penetrates the casings 41g, 91g, and 92g in the left-right direction.

[0036] Rotation of the pump shaft 42 activates the pumps 41, 91, and 92. In this case, the feed pump 41 sucks oil from the oil pan 22 through the oil strainer 23 and pumps it to an oil line formed in the left crankcase 11L. Reference numeral 93 in FIG. 8 denotes a relief valve. The relief valve 93 adjusts the oil pressure in the oil line to an appropriate range. The oil that has lubricated the parts to be lubricated is supplied to the oil pan 22 by the first suction oil pump 91 and the second suction oil pump 92 via the oil cooler 28.

[0037] As shown in FIG. 8, the first suction oil pump 91 that sucks oil from the generator chamber 11e is disposed on the leftmost side, and therefore can efficiently suck oil from the generator chamber 11e. Furthermore, since this engine 1 has an independent communication passage 80 that connects the generator chamber 11e and the clutch chamber 11d, the first suction oil pump 91 can also suck oil from the clutch chamber 11d. In other words, the first suction oil pump 91 serves as both an oil pump that sucks oil from the generator chamber 11e and an oil pump that sucks oil from the clutch chamber 11d. This allows the number of oil pumps to be reduced. The first suction oil pump 91 is an example of an accessory compartment suction oil pump, and the second suction oil pump 92 is an example of a crank chamber suction pump.

[0038] Next, the structure relating to the assembly of the pump shaft 42 and the left and right crankcases 11R, 11L will be described. 8, the pump shaft 42 is configured to pass through the right crankcase 11R but not through the left crankcase 11L. The pump shaft 42 is configured to be fixed to the left crankcase 11L. An oil pump driven gear 94 is attached to the right end of the pump shaft 42. Furthermore, an accessory drive oil pump 95 for driving hydraulic control system accessories is disposed on the pump shaft 42 between the oil pump driven gear 94 and the feed pump 41 .

[0039] The oil pump driven gear 94 meshes with a gear to which rotation from the crankshaft 10 is transmitted. This gear train is disposed in the clutch chamber 11d. The hydraulic control system accessories are not particularly limited, but may be, for example, a hydraulic actuation mechanism of the clutch mechanism 51 or a hydraulic actuation mechanism of the transmission 21. The accessory drive oil pump 95 is a pump that is necessary when hydraulic control system accessories are included, but is not necessary when hydraulic control system accessories are not included. This accessory drive oil pump 95 is composed of a casing 95g that is formed integrally with the right crankcase 11R, and a pump rotor 95a that is attached to the pump shaft 42. When hydraulic control system accessories are not included, the pump rotor 95a is not attached, and the right crankcase 11R is shared.

[0040] When assembling the engine, as shown in Figure 9, the left crankcase 11L is rotated 90 degrees and installed, and the pump shaft 42 is fixed to the left crankcase 11L. Then, the narrower right crankcase 11R is moved downward from above relative to the left crankcase 11L, thereby inserting the pump shaft 42 into the right crankcase 11R, and the right crankcase 11R is moved to a position where it will be joined to the left crankcase 11L. This procedure improves the ease of assembly of the engine 1, and in particular, the narrower right crankcase 11R is relatively light, making the crankcase movement procedure easier.

[0041] When assembling the pump shaft 42 and the left and right crankcases 11R, 11L, certain parts around the pump shaft 42 (such as the oil pump driven gear 94 and the pump rotor 95a of the accessory drive oil pump 95) must be removed in advance so as not to interfere with the assembly work. Also, some parts cannot be attached after the crankcases 11L, 11R are fixed together. For example, the pump rotors 92g, 91g, and 41g on the left crankcase 11L side must be attached to the pump shaft 42 in advance.

[0042] Furthermore, the dividing plane LD of the crankcase 11 is not limited to being offset to the right of the stud bolts 71 between the cylinders, but may be offset to the left of the stud bolts 71 between the cylinders. Furthermore, at least a portion of the internal structure of the engine, including the main shaft 31, the pump shaft 42, and the oil pumps 41, 91, 92, and 95, may be arranged or structured symmetrically.

[0043] As described above, in the engine 1 of this embodiment, as shown in Fig. 2, the dividing plane LD of the crankcase 11 is offset to the left or right from the stud bolts 71 between the cylinders, and the main shaft 31 is attached to the left crankcase 11L at a position where it penetrates the narrower right crankcase 11R on one side but does not penetrate the wider left crankcase 11L on the other side. Furthermore, when certain parts around the main shaft 31, including the right crankcase 11R, are not attached, with the main shaft 31 attached to the left crankcase 11L, the right crankcase 11R can be moved to a position where the main shaft 31 is inserted through it and fixed to the left crankcase 11L.

[0044] With this configuration, the stud bolts 71 between the cylinders can be attached to positions that allow for uniform fastening of the cylinder section 12F of the engine 1 while avoiding the position of the dividing plane LD of the crankcase 11, and as shown in Figure 7, during engine assembly, the main shaft 31 can be attached to the wide left crankcase 11L, and then the narrow right crankcase 11R can be moved and the main shaft 31 inserted through said case 11R to fasten the crankcases 11 together. The narrow right crankcase 11R is relatively light, which improves the ease of assembly of the engine 1.

[0045] The right crankcase 11R corresponds to the first crankcase of the present disclosure, and the left crankcase 11L corresponds to the second crankcase of the present disclosure. 3, the cam chain chamber 73 is located on one side of the cylinder block 12a in the direction in which the cylinders are aligned, and the dividing plane LD of the crankcase 11 is offset toward the cam chain chamber 73. This configuration improves assembly of the cam chain and its surroundings.

[0046] 8, the stud bolts 71 between the cylinders are fitted into the wide left crankcase 11L, and the casings 41g, 91g, and 92g of the oil pumps 41, 91, and 92 are formed in the left crankcase 11L, and the pump rotors 41r, 91r, and 92r are disposed inside the casings 41g, 91g, and 92g. With this configuration, the pump rotors 41r, 91r, and 92r can be made wide, ensuring the capacity of the oil pump without increasing the outer diameter of the pump rotors 41r, 91r, and 92r.

[0047] Additionally, an oil pan 22 is integrally formed at the bottom of the crankcase 11, and the oil pan 22 is divided into left and right halves formed in each of the crankcases 11L, 11R. This configuration prevents an increase in the number of parts and improves the ease of assembly of the engine 1.

[0048] Furthermore, the crank chamber inside the crankcase 11 is a sealed crank chamber 11a in which oil in this crank chamber is sucked by a second suction oil pump 92, and the second suction oil pump 92 and the feed pump 41 which functions as a lubrication oil pump that supplies oil to lubrication points are arranged side by side in the crankcase 11. With this configuration, multiple oil pumps can be consolidated and the structure around the oil pumps can be simplified, improving the ease of assembly of the engine 1.

[0049] The engine 1 also has a generator chamber 11e and a clutch chamber 11d that make up left and right accessory chambers, and a first suction oil pump 91 that functions as an accessory chamber suction oil pump that sucks oil from the generator chamber 11e and the clutch chamber 11d, and the first suction oil pump 91 is arranged alongside the second suction oil pump 92 and the feed pump 41. With this configuration, multiple oil pumps can be consolidated, simplifying the structure around the oil pumps and improving the ease of assembly of the engine 1.

[0050] Furthermore, the engine 1 of this embodiment is equipped with a first suction oil pump 91 that sucks oil from the generator chamber 11e constituting one of the left and right accessory compartments and discharges it into the oil pan 22, and communication passages 80 (left communication passage 80L and right communication passage 80R) that connect the generator chamber 11e and the clutch chamber 11d constituting the left and right accessory compartments and move oil from the clutch chamber 11d to the generator chamber 11e by the suction force of the first suction oil pump 91. With this configuration, the oil supplied to the left and right accessory compartments can be sucked by a common oil pump, thereby reducing the number of parts and weight of the engine 1.

[0051] Additionally, the casing 91g of the first suction oil pump 91 and the communication passage 80 are formed in the crankcase 11. With this configuration, the number of parts in the engine 1 can be reduced compared to when the casing 91g and the communication passage 80 are manufactured as separate parts.

[0052] The engine 1 also has a second suction oil pump 92 that functions as a crank chamber suction oil pump that sucks oil from the crank chamber inside the crankcase 11, and the second suction oil pump 92 is arranged on the same axis as the first suction oil pump 91. With this configuration, the pump shaft 42 that serves as the drive shaft for the two oil pumps 92, 91 can be shared, thereby reducing the number of parts in the engine 1.

[0053] The engine 1 also has a feed pump 41 that supplies oil from the oil pan 22 to lubrication points, and the feed pump 41 is arranged on the same shaft as the first suction oil pump 91 and the second suction oil pump 92. With this configuration, the pump shaft 42 that serves as the drive shaft for the three oil pumps 41, 91, and 92 can be shared, thereby reducing the number of parts in the engine 1.

[0054] The crankcase 11 is divided into left and right sections, and the first suction oil pump 91, the second suction oil pump 92, and the feed pump 41 are arranged on the same axis in the left crankcase 11L. With this configuration, the three oil pumps 91, 92, and 41 can be arranged together in the left crankcase 11L, improving the assembly of the engine 1.

[0055] Additionally, an oil pump driven gear 94 and the like that constitute the gear train of the oil pump drive system are disposed in the right crankcase 11R. With this configuration, the structure around the oil pump is simplified, and the assembly of the engine 1 is improved.

[0056] The right crankcase 11R also has an accessory drive oil pump 95 that functions as another oil pump that supplies oil to hydraulic control system accessories, and the accessory drive oil pump 95 is disposed on the same axis as the other oil pumps 91, 92, and 41. With this configuration, the four oil pumps 95, 91, 92, and 41 can be consolidated, simplifying the structure around the oil pumps and improving the assembly of the engine 1.

[0057] [Other embodiments] The above-described embodiment merely shows one aspect of the present invention, and any modifications and applications are possible without departing from the spirit of the present invention.

[0058] For example, in the above embodiment, the dividing plane LD of the crankcase 11 is offset to the right of the stud bolts 71 between the cylinders, but this is not limitative and the dividing plane LD may be offset to the left of the stud bolts 71 between the cylinders. Also, the main shaft 31 and the oil pumps may be shaped and positioned symmetrically. Furthermore, in the above embodiment, the present invention has been described as being applied to the engine 1 shown in Figure 1 etc., and to a manufacturing method (assembly method) for the engine 1, but the present invention may also be applied to an engine different from engine 1, and to a manufacturing method (assembly method) for that engine. Furthermore, the engines to which the present invention can be applied are not limited to engines mounted on motorcycles, but may also be applied to engines mounted on saddle-ride vehicles including vehicles other than motorcycles, vehicles other than saddle-ride vehicles, and moving bodies other than vehicles.

[0059] [Configuration supported by the above embodiment] The above embodiment supports the following configurations.

[0060] (Configuration 1) An engine in which a left-right split crankcase, a parallel twin-cylinder cylinder block, and a cylinder head are fastened with stud bolts, and a main shaft and a counter shaft that form at least part of a transmission are provided within the crankcase, wherein the split surface of the crankcase is offset to the left or right from the stud bolts between the cylinders, and the main shaft is attached to the second crankcase at a position where it passes through a narrow first crankcase on one side and does not pass through a wide second crankcase on the other side, and when certain parts around the main shaft, including the first crankcase, are not attached, the engine is capable of moving the first crankcase to a position where the main shaft is inserted and fixed to the second crankcase with the main shaft attached to the second crankcase. With this configuration, the stud bolts between the cylinders can be installed in positions that allow the cylinder sections of the engine to be fastened evenly while avoiding the positions of the crankcase dividing surfaces, and during engine assembly, the main shaft can be attached to the wider second crankcase, and then the narrower first crankcase can be moved to insert the main shaft through it, thereby connecting the crankcases.The narrower first crankcase can be made relatively light, improving engine assembly workability.

[0061] (Configuration 2) The engine according to configuration 1, wherein the cylinder block has a cam chain chamber on one side in the direction of cylinder alignment, and the dividing surface of the crankcase is offset toward the cam chain chamber. This configuration improves assembly efficiency around the cam chain.

[0062] (Configuration 3) The engine according to configuration 1 or 2, wherein the stud bolts between the cylinders are fitted into the second crankcase, a casing for an oil pump is formed in the second crankcase, and a pump rotor is disposed within the casing. According to this configuration, the pump rotor can be made wider, and the capacity of the oil pump can be ensured without increasing the outer diameter of the pump rotor.

[0063] (Configuration 4) An engine according to any one of configurations 1 to 3, wherein an oil pan is integrally formed in a lower portion of the crankcase, and the oil pan is divided into left and right halves and formed in each of the first crankcase and the second crankcase. This configuration prevents an increase in the number of parts and improves the ease of assembly of the engine.

[0064] (Configuration 5) An engine described in any one of configurations 1 to 4, wherein the crank chamber in the crankcase is a sealed crank chamber in which oil in the crank chamber is sucked by a suction oil pump, and the suction oil pump and a lubrication oil pump that supplies oil to lubrication points are arranged side by side in the crankcase 11. According to this configuration, multiple oil pumps can be consolidated, the structure around the oil pumps can be simplified, and the engine assembly workability can be improved.

[0065] (Configuration 6) The engine has left and right auxiliary machinery chambers and an auxiliary machinery chamber suction oil pump that sucks oil from the left and right auxiliary machinery chambers, and the auxiliary machinery chamber suction oil pump is arranged alongside the suction oil pump and the lubrication oil pump. According to this configuration, multiple oil pumps can be consolidated, the structure around the oil pumps can be simplified, and the engine assembly workability can be improved.

[0066] (Configuration 7) A method for manufacturing an engine in which a left-right split crankcase, a parallel twin-cylinder cylinder block, and a cylinder head are fastened together with stud bolts, and a main shaft and a counter shaft that form at least part of a transmission are provided within the crankcase, wherein the split surface of the crankcase is offset to the left or right from the stud bolts between the cylinders, and the main shaft is a member that passes through a narrow first crankcase on one of the left or right sides and is attached to the second crankcase at a position that does not pass through a wide second crankcase on the other left or right side, and during engine assembly, the main shaft is attached to the second crankcase, and the first crankcase is joined to the second crankcase by inserting the main shaft into it. This configuration improves the ease of engine assembly. [Explanation of symbols]

[0067] 1...Engine (internal combustion engine) 10 crankshaft 10c Crankweb 11 Crankcase 11 11a Sealed crankcase 11b Transmission compartment 11d Clutch compartment (auxiliary compartment) 11e Generator room (auxiliary machinery room) 11L Left crankcase (second crankcase) 11R Right crankcase (first crankcase) 12F Cylinder section 12a cylinder block 12b cylinder head 12c headcover 21 Transmission 22 Oil pan 31 Main shaft 32 Counter axis 41 Feed pump (lubrication oil pump) 41g, 91g, 92g, 95g Oil pump casing 41r, 91r, 92r, 95a pump rotor 42 Pump shaft 51 Clutch mechanism (auxiliary) 61 Generator (auxiliary) 71 Stud bolt 73 Cam chain compartment 91 No. 1 suction oil pump (auxiliary compartment suction oil pump) 92 Second suction oil pump (crankcase suction oil pump) 95 Auxiliary drive oil pump LD crankcase split surface

Claims

1. An engine having a left-right split crankcase (11), a parallel twin-cylinder cylinder block (12a), and a cylinder head (12b) fastened together with stud bolts (71), and having a main shaft (31) and a counter shaft (32) constituting at least a part of a transmission (21) inside the crankcase (11), The dividing surface (LD) of the crankcase (11) is offset to the left or right from the stud bolt (71) between the cylinders, the main shaft (31) penetrates through one of the left and right narrow first crankcases (11R) and is attached to the second crankcase (11L) at a position where it does not penetrate through the other of the left and right wide second crankcases (11L); When predetermined parts around the main shaft (31) including the first crankcase (11R) are not attached, the first crankcase (11R) is freely moved to a position where the main shaft (31) is inserted and fixed to the second crankcase (11L) in a state where the main shaft (31) is attached to the second crankcase (11L). engine.

2. A cam chain chamber (73) is provided on one side of the cylinder block (12a) in the direction of cylinder alignment, The dividing surface (LD) of the crankcase (11) is offset toward the cam chain chamber (73).

10. The engine of claim 1.

3. The stud bolts (71) between the cylinders are fitted into the second crankcase (11L), The second crankcase (11L) is formed with casings (41g, 91g, 92g) of oil pumps (41, 91, 92), Pump rotors (41r, 91r, 92r) are disposed in the casings (41g, 91g, 92g).

10. The engine of claim 1.

4. An oil pan (22) is integrally formed at the bottom of the crankcase (11), The oil pan (22) is divided into left and right halves and formed in the first crankcase (11R) and the second crankcase (11L), respectively.

10. The engine of claim 1.

5. The crank chamber (11a) in the crankcase (11) is a sealed crank chamber (11a) in which oil is sucked by a suction oil pump (91), The suction oil pump (91) and the lubrication oil pump (41) that supplies oil to lubrication points are arranged side by side in the crankcase (11).

10. The engine of claim 1.

6. The engine has left and right auxiliary machinery chambers (11d, 11e) and an auxiliary machinery chamber suction oil pump (92) that sucks oil from the left and right auxiliary machinery chambers (11d, 11e), The auxiliary machinery compartment suction oil pump (92) is arranged alongside the suction oil pump (91) and the lubrication oil pump (41).

6. The engine of claim 5.

7. A method for manufacturing an engine comprising a left-right split crankcase (11), a parallel twin-cylinder cylinder block (12a), and a cylinder head (12b) fastened together with stud bolts (71), the engine being provided with a main shaft (31) and a counter shaft (32) constituting at least a part of a transmission (21) within the crankcase (11), The dividing surface (LD) of the crankcase (11) is offset to the left or right from the stud bolt (71) between the cylinders, the main shaft (31) is a member that penetrates the narrow first crankcase (11R) on one of the left and right sides and is attached to the wide second crankcase (11L) on the other of the left and right sides at a position where it does not penetrate the wide second crankcase (11L), When assembling the engine, the main shaft (31) is attached to the second crankcase (11L), and the first crankcase (11R) is inserted onto the main shaft (31) and joined to the second crankcase (11L). Engine manufacturing method.

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