JP2006207431A - V-type internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To facilitate assembling of bodies of throttle bodies to insulators and reduce the size of an intake system, in a V-type internal combustion engine with the intake system arranged in a bank space. <P>SOLUTION: Guide parts 69a, 69b are provided in only part of upstream end parts 64a1, 64b1, such that fitting parts 61a1, 61b1 of the throttle bodies 61a, 61b are guided to fitting holes 66a, 66b of the insulators 64a, 64b while contacting with guide faces 69a1, 69b1, when the throttle bodies 61a, 61b are assembled to the insulators 64a, 64b from a direction parallel with a specific plane P0. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a V-type internal combustion engine including an intake device disposed in a bank space formed by a V bank.

In the internal combustion engine disclosed in Patent Document 1 as a V-type internal combustion engine of this type, an insulator is attached to an opening end of an intake port provided in a cylinder head of each bank, and each insertion of a throttle body is inserted into each opening of the insulator. The end is inserted.
Japanese Patent No. 2723990

  In the prior art, when the throttle body is assembled to the insulator, the lower end of each insertion end of the throttle body and the upper end of the opening of each insulator are on a plane perpendicular to the insertion direction. Can be easily assembled, but the opening area of the intake passage and the opening area of the insulator opening at each insertion end are the cross-sectional area of the flow path (the cross-sectional area of the flow path that is perpendicular to the central axis of the intake path) Therefore, it is difficult to reduce the size of the intake device including the throttle body and the insulator.

  The present invention has been made in view of such circumstances, and the invention according to claims 1 to 4 is a V-type internal combustion engine including an intake device arranged in a bank space, and a body of a throttle body to an insulator. It is an object to reduce the size of the intake device. Further, the present invention has the object of further improving the assembly of the body of the throttle body to the insulator.

  According to the first aspect of the present invention, the first and second cylinders are arranged in a V shape so that the V type is provided with an intake device disposed in the bank space between the first and second banks constituting the V bank. An internal combustion engine, wherein the intake device includes a throttle body and an insulator having an upstream end portion that forms a fitting hole into which a fitting portion constituted by a downstream end portion of the throttle body is fitted. In the internal combustion engine, a guide portion is provided only at a part of the upstream end portion, and when the throttle body is assembled to the insulator, the fitting portion is guided to the fitting hole while contacting the guide portion. This is a V-type internal combustion engine.

  According to this, since the insulator is provided with the guide portion that guides the fitting portion to the fitting hole when the throttle body is assembled to the insulator, the assembly is facilitated, and the guide portion is upstream. Since it is provided only at a part of the end portion, an increase in size of the insulator due to the provision of the guide portion is suppressed.

  According to a second aspect of the present invention, in the V-type internal combustion engine according to the first aspect, the throttle body includes a first throttle body provided in the first bank and a second throttle body provided in the second bank. The insulator includes a first insulator to which the first throttle body is assembled and a second insulator to which the second throttle body is assembled, and the first and second throttle bodies are integrally connected to each other. The guide part is composed of first and second guide parts provided in the first and second insulators, respectively.

  According to this, in the state where the first and second throttle bodies are integrally connected, they are guided and assembled at the same time by the first and second guide portions provided in the first and second insulators.

  According to a third aspect of the present invention, in the V-type internal combustion engine according to the first aspect, in the insulator, the guide portion is provided in one of the near side and the far side with respect to the bank space, and the proximity is provided in the insulator. The fuel injection valve is attached to the throttle body at a position corresponding to the other portion on the side and the far side.

  According to this, at the time of assembly, the fuel injection valve attached to the throttle body and the guide portion provided on the insulator do not interfere with each other.

  According to a fourth aspect of the present invention, in the V-type internal combustion engine according to any one of the first to third aspects, the guide portion extends along a central axis of the fitting hole with respect to the fitting hole. It protrudes in the direction away.

  According to this, since a guide part can be enlarged along an assembly direction, a fitting part is guided by a guide part from the early stage of an assembly process at the time of an assembly.

  According to invention of Claim 1, the following effect is show | played. That is, the guide part facilitates the assembly of the throttle body to the insulator, and the provision of the guide part suppresses an increase in the size of the insulator. The air intake device can be reduced in size.

  According to invention of Claim 2, in addition to the effect of the invention of the cited claim, there exists the following effect. That is, since the first and second throttle bodies are guided by the first and second guide portions and are simultaneously assembled to the first and second insulators, the assemblability is further improved.

  According to invention of Claim 3, in addition to the effect of the invention of the cited claim, there exist the following effects. That is, when the throttle body is assembled to the insulator, the fuel injection valve and the guide portion do not interfere with each other, so that good assemblability is ensured.

  According to invention of Claim 4, in addition to the effect of the invention of the cited claim, there exists the following effect. That is, when the throttle body is assembled to the insulator, the fitting portion is guided by the guide portion from an early stage of the assembling process, so that the assembling property is further improved.

Hereinafter, embodiments of the present invention will be described with reference to FIGS.
1 and 2, an internal combustion engine E to which the present invention is applied is mounted on a scooter type motorcycle as a vehicle together with a power transmission device. The power transmission device includes a belt-type continuously variable transmission M as a transmission, a centrifugal clutch C as a starting clutch, a gear-type transmission mechanism R1 as a primary reduction mechanism, and a chain-type transmission mechanism R2 as a secondary reduction mechanism. The power generated by the internal combustion engine E in this order is transmitted to the rear wheels as drive wheels. The power unit including the internal combustion engine E, the transmission M, the centrifugal clutch C, and the gear type transmission mechanism R1 is fixed to the vehicle body frame via a pair of left and right engine hangers 59 (see also FIG. 7).

  The internal combustion engine E mounted on the motorcycle in a horizontal arrangement in which the rotation center line L0 of the crankshaft 7 is directed in the left-right direction is an OHC type, water-cooled, V-type two-cylinder, four-stroke internal combustion engine, which is approximately 90 °. A pair of cylinders 1a and 1b arranged in a V shape so as to form a bank angle θ1 (see FIG. 3), and base ends of the cylinders 1a and 1b in the directions A1 and A2 of the cylinder axis L1a and L1b A pair of cylinder heads 3a and 3b which are joined to the cylinders 1a and 1b and integrated with the cylinders 1a and 1b. An engine body including a pair of head covers 4a and 4b coupled to the cylinder heads 3a and 3b is provided.

  In this embodiment, up, down, front and back, and left and right respectively mean up and down, front and back, and left and right when a motorcycle is used as a reference. The side view means viewing from the direction of the rotation center line L0 of the crankshaft 7 (hereinafter simply referred to as “rotation center line direction”).

  Referring also to FIG. 3, the front bank B1 as the first bank and the rear bank B2 as the second bank constituting the V bank respectively include the cylinder 1a as the first cylinder and the cylinder 1b as the second cylinder. Configured as the subject. More specifically, the front bank B1 includes a cylinder 1a that has a cylinder axis L1a slightly inclined forward and obliquely upward and is largely inclined forward, a cylinder head 3a, and a head cover 4a. A cylinder 1b having a slightly tilted cylinder axis L1b obliquely upward and rearward is provided, a cylinder head 3b, and a head cover 4b.

  A crankshaft 7 connected via a connecting rod 6 to a piston 5 that is reciprocally fitted to each cylinder 1a, 1b has a journal 7c, 7d, a plain bearing 8 as a pair of main bearings in the crankcase 2. 9 is supported rotatably. The left and right crankcase 2 that forms the crank chamber 10 that houses the crankshaft 7 includes first and second crankcases 2a and 2b that are divided into two by a plane orthogonal to the rotation center line L0. Sliding bearings 8 and 9 disposed between the bearing portions 2a1 and 2b1 of the first and second crankcases 2a and 2b and the journals 7c and 7d are bearings in which no oil grooves are formed, and the bearing portions 2a1 and 2b1 Lubricating oil is supplied from the formed oil passages K6a and K6b.

  2 and 3, the cylinder heads 3a and 3b, which are fastened together with the cylinders 1a and 1b to the crankcase 2 by six head bolts 11 and 12 (see also FIG. 4), have a cylinder axial direction A1. , A 2, a combustion chamber 13 facing the piston 5, an intake port 14 having a pair of intake ports opening in the combustion chamber 13, and an exhaust port 15 having a pair of exhaust ports opening in the combustion chamber 13 are formed. A spark plug 16 (see FIG. 1) is attached. Further, each cylinder head 3a, 3b includes a pair of intake valves 17 and a pair of exhaust valves as engine valves each composed of a tappet valve that opens and closes the pair of intake ports and the pair of exhaust ports, respectively. 18 is provided. Each intake valve 17 and each exhaust valve 18 are opened and closed at a predetermined timing by a valve gear 21 including a cam shaft 22 that is rotationally driven by the power of the crankshaft 7. Further, as shown in FIG. 5, the intake port 14 branches into a pair of branch ports 14a and 14b having the respective intake ports, and the exhaust port 15 has a pair of branch ports 15a having the respective exhaust ports. , 15b. The spark plug 16 is disposed to be inclined between the branch port 14b and the branch port 15b (see FIG. 6A) and faces the center of the combustion chamber 13.

  Referring also to FIG. 4, in each of the banks B1 and B2, the valve operating device 21 housed in the valve operating chamber 20 formed by the joint of the cylinder heads 3a and 3b and the head covers 4a and 4b includes the cylinder head 3a, A cam shaft 22 rotatably supported by 3b, an intake rocker arm 25 and an exhaust rocker arm 26 that are driven by and swinged by an intake cam 23 and an exhaust cam 24 provided on the cam shaft 22, and an intake rocker arm 25 and an exhaust rocker arm 26, respectively. Are respectively provided with an intake rocker arm shaft 27 and an exhaust rocker arm shaft 28 that are swingably supported. Since the valve gears 21 of the banks B1 and B2 have the same structure, the following description will focus on the valve gear 21 of the front bank B1, and members related to the rear bank B2 such as the valve gear 21 will be described below. A code is shown in parentheses as necessary.

  Referring also to FIG. 6, the cam shaft 22 having a rotation center line parallel to the rotation center line L0 is a member in the valve operating chamber 20 and is attached to a cam holder 29 provided integrally with the cylinder head 3a (3b). It is supported via a bearing. The cam holder 29 is a plurality of, in this embodiment, a pair of cam holder portions 29a protruding from the upper deck 3a1 (3b1) forming the cooling water jacket W3 (W6) of the cylinder head 3a (3b) toward the head cover 4a (4b). , 29b. The left end portion 22a of the cam shaft 22 is supported by one cam holder portion 29a via a bearing 30 made of a ball bearing, and the right end portion 22b of the cam shaft 22 is supported by a cam holder portion 29b via a bearing 31 made of a needle bearing. Is done.

  Referring also to FIG. 7, the camshaft 22 is rotationally driven by the power of the crankshaft 7 transmitted via the valve gear transmission mechanism T1 (T2). The valve transmission mechanism T1 (T2) includes a drive sprocket 32a (32b) as a drive rotator provided on the crankshaft 7 and a cam sprocket as a driven rotator provided on the left end 22a of the camshaft 22. 33a (33b) and a chain 34a (34b) as an endless transmission band wound around the drive sprocket 32a (32b) and the cam sprocket 33a (33b).

  The rocker arm shafts 27 and 28 arranged in parallel with the cam shaft 22 are closer to the head covers 4a and 4b than the cam shaft 22 and are axially connected to both cam holder portions 29a and 29b which are holders provided on the cylinder heads 3a and 3b. Is maintained in a restricted state. More specifically, the rocker arm shafts 27 and 28 are respectively provided on the cam sprocket 33a (33b) side in holding holes 29a1, 29b1; 29a2, 29b2 (see FIG. 8) formed of through holes provided in the cam holder portions 29a, 29b. And a plurality of, in this case, a pair of bolts 34, 35 as restricting members that abut against the rocker arm shafts 27, 28 after being inserted in the axial direction from the opposite side to the cam sprocket 33a (33b) side. The movement of the rocker arm shafts 27 and 28 in the axial direction is restricted and the rotation is restricted by 36 and 37. Therefore, bolts 34, 35; 36, 37 as fixing means are inserted into the left and right ends 27a, 27b; 28a, 28b, which are held parts held by the cam holder 29, in the respective rocker arm shafts 27, 28. An insertion portion is formed. In this embodiment, the insertion portion is constituted by a through hole extending in a direction orthogonal to the axial direction of the rocker arm shafts 27 and 28 and having a central axis intersecting the central axis of the rocker arm shafts 27 and 28. You may be comprised by the through-hole which cross | intersects the central axis of 27 and 28, or the through-hole or notch offset from this central axis.

  7 and 8, the bolts 34 and 36 pass through the left end portions 27a and 28a in a direction inclined with respect to the cylinder axial direction A1 (A2) and are screwed into the screw holes 38 of the first cam holder portion 29a. . The screw hole 38 is formed so that the stem of the intake valve 17 penetrates the cylinder head 3a (3b) and is formed in parallel with the through hole 40 (see FIG. 3) into which the tubular valve guide 39 is press-fitted. 22 is inclined at the same angle as the inclination angle of the intake valve 17 slidably supported by the valve guide 39 with respect to the cylinder axis L1a (L1b) when viewed from the axial direction. Since the screw hole 38 is parallel to the through hole 40 through which the intake valve 17 is inserted, the screw hole 38 can be machined from the same direction simultaneously with the machining of the through hole 40. improves.

Then, the screw hole 38 into which the bolt 36 is screwed is inclined so as to avoid the bearing 30 at the position overlapping the bolt 36 at the position in the cylinder axial direction A1 (A2).
Since the rocker shaft 28 can be disposed close to the cam shaft in the direction orthogonal to the cylinder axial direction A1 (A2) when viewed from the axial direction and the cylinder axial direction A1 (A2), the cylinder head 3a (3b ) Can be reduced in size, and the depth of the screw 38 can be increased without interfering with the bearing 30, so the length of the threaded portion of the bolt 36 can be increased and the rocker arm shaft 28 can be more firmly fixed. become. Further, since the distance D from the outer surface of the rocker arm shaft 28 to the outer surface of the cam holder 29a can be increased in a direction perpendicular to the axis L5 (that is, the tightening direction) of the bolt 36 as viewed from the axial direction, a large tightening force is secured. it can.

  Some bolts 34 of the bolts 34, 35, 36, and 37 extend to a position overlapping with the outer race 30 a of the bearing 30 when viewed from the axial direction of the cam shaft 22, or are in contact with the bearing 30 in the axial direction or the bearing 30. Since it also serves as a restricting member that restricts the bearing 30 from moving in the axial direction, a dedicated restricting member becomes unnecessary, and the number of parts is reduced in this respect as well. Further, since the rocker arm shaft 28 can be disposed close to the cam shaft 22 in the direction orthogonal to the cylinder axis direction A1 (A2) when viewed from the axial direction and the cylinder axis direction A1 (A2), both directions Thus, the cylinder head 3a (3b) can be reduced in size. Further, the function of the bolt 34 that restricts the movement of the bearing 30 in the axial direction is easily achieved by the inclination of the bolt 34 so as to approach the cam shaft 22 in the screwing direction.

  Referring to FIG. 6, the bolts 35 and 37 pass through the right end portions 27b and 28b and are screwed into the cam holder portion 29b substantially parallel to the cylinder axial direction A1 (A2). Among these, the bolt 37 that penetrates the exhaust rocker arm shaft 28 is a part of a plurality of bolts that connect the head cover 4a (4b) to the cylinder head 3a (3b), in this embodiment, a pair of bolts 37 and 41. Therefore, the bolt 37 that couples the head cover 4a (4b) to the cylinder head 3a (3b) also serves as a regulating member that regulates the movement of the exhaust rocker arm shaft 28 in the axial direction.

  Referring to FIG. 6B, the bolt 37 screwed into the screw hole 29b4 formed in the cam holder portion 29b is composed of a head portion 37a and a shaft portion 37b that contacts the exhaust rocker arm shaft 28 in the axial direction. The head portion 37a includes a large-diameter portion 37a1 that presses the head cover 4a (4b) via the seal member 42 outside the valve train chamber 20, and a small-diameter portion 37a2 that is smaller in diameter than the large-diameter portion 37a1. The small diameter portion 37a2 has a contact surface 37c that penetrates the through hole of the head cover 4a (4b) and contacts the outer surface 39b3 of the cam holder portion 29b in the valve operating chamber 20 in the cylinder axial direction A1 (A2). The shaft portion 37b extends substantially parallel to the cylinder axis L1a (L1b) from the contact surface 37c.

  Each rocker arm shaft 27, 28 can be inserted and removed in the axial direction from the side opposite to the cam sprocket 33a (33b) side with the head cover 4a (4b) removed and the bolts 34, 35, 36, 37 removed. Therefore, without removing the cam sprocket 33a (33b) from the cam shaft 22, the two rocker arm shafts 27 and 28 that are in a position overlapping the cam sprocket 33a (33b) when viewed from the axial direction (in side view) can be connected to the cylinder head. 3a (3b) so that the cam sprocket 33a (33b) remains connected to the camshaft 22 and the rocker arms 25 and 26 are removed, and the end portions of the stems of the intake valve 17 and the exhaust valve 18 are removed. It is easy to adjust the valve clearance using a shim placed on the head.

  Further, the rocker arm shaft 28 is formed with an insertion portion 28c into which a bolt 36 is inserted at one end portion 28a (see FIG. 8), and an insertion portion 28d into which the bolt 37 is inserted at the other end portion 28b. The Then, before the head cover 4a (4b) is coupled to the cylinder head 3a (3b) by the bolt 37 screwed into the cam holder portion 29b, the rocker arm shaft 28 is inserted into the insertion portion 28c and screwed into the cam holder portion 29a. Thus, the insertion portion 28d is positioned in the axial direction and the circumferential direction so as to be aligned with the screw hole 29b4 with respect to the cam holder portion 29a (29b), and is fixed so as not to move and rotate in the axial direction.

  Referring to FIG. 2, the crankcase cover 45 coupled to the left side of the first crankcase 2a and the first crankcase 2a include an auxiliary machine chamber 47 in which an AC generator 46 serving as an auxiliary machine is accommodated, and the auxiliary room. An oil tank 48 is formed adjacent to the rear of the machine room 47.

  Referring also to FIG. 7, the crankshaft 7 passes through the first crankcase 2 a, and slips on the shaft end 7 a of the crankshaft 7 projecting leftward from the first crankcase 2 a in the accessory chamber 47. The drive sprocket group as the drive rotating body group, the one-way clutch 51 connected to the starter motor 49 via the starter reduction gear 50a and the rotor 46a of the alternator 46 in order from the bearing 8 side. Is attached. The one-way clutch 51 includes an input member 51a rotatably supported by the shaft end 7a, an output member 51b integrally coupled to the rotor 46a, and a plurality of members disposed between the input member 51a and the output member 51b. Claw 51c.

  The drive sprocket group includes a drive sprocket 32b constituting the valve drive transmission mechanism T2 of the rear bank B2, an oil pump 80 (see FIG. 10) as an auxiliary device, and a cooling water pump 130 (see FIG. 10). 10), the drive sprocket 32c constituting the accessory drive transmission mechanism T3 and the drive sprocket 32a constituting the valve train transmission mechanism T1 of the front bank B1 are arranged in this order. As described above, in the internal combustion engine E in which the drive sprockets 32a and 32b of the pair of valve transmission mechanisms T1 and T2 are provided at the same shaft end portion 7a of the crankshaft 7, between the pair of drive sprockets 32a and 32b. Since the drive sprocket 32c for driving the auxiliary machine is provided using this space, space efficiency is improved and the internal combustion engine E can be downsized in the direction of the rotation center line.

  A guide 53 for guiding the chains 34a and 34b is disposed on the tension side of the chains 34a and 34b whose tension is adjusted by the tensioner 52. The end portion of the guide 53 near the crankshaft 7 is supported by receiving portions 54 and 55 protruding from the bearing portion 2a1 in the direction of the rotation center line. Of the two chains 34a and 34b, the guide 53 of the chain 34a close to the one-way clutch 51 in the axial direction extends to a position close to the starter driven gear 50a integrally coupled to the input member 51a of the one-way clutch 51. . The input member 51a and the starting driven gear 50a are restricted by the rotor 46a from moving to the left in the direction of the rotation center line, and from the right by the receiving portion 55. In this way, the receiving portion 55 functions as a stopper that restricts the movement of the one-way clutch 51 and the starter driven gear 50a in the direction of the rotation center line. Therefore, it is necessary to separately provide a dedicated stopper that restricts the movement of the receiving portion 55. And the number of parts is reduced.

  Referring to FIG. 2, a transmission case 56 separate from the second crankcase 2b is coupled to the right side of the second crankcase 2b. A transmission case 56 forming a transmission chamber 57 in which the transmission M is accommodated includes a first transmission case 56a coupled to the second crankcase 2b by a bolt and a second coupled to the right side of the first transmission case 56a. It is comprised from the transmission case 56b. The crankshaft 7 passes through the second crankcase 2b and the first transmission case 56a, and a transmission M having a belt 164 is provided at a shaft end portion 7b protruding rightward from the first transmission case 56a in the transmission chamber 57. Drive coupled. In addition to the transmission M, a centrifugal clutch C is accommodated in the transmission chamber 57. A gear type transmission mechanism R1 is housed in a gear chamber 58 formed by the rear portion 2a2 of the first crankcase 2a forming the oil tank 48 and the rear portion 56a2 of the first transmission case 56a.

  Thus, the first transmission case 56a forming the transmission chamber 57 is a separate member from the second crankcase 2b disposed adjacent to the vicinity of the first transmission case 56a. Since the heat is suppressed from being transmitted to the first transmission case 56a, the temperature rise of the belt 164 accommodated in the transmission chamber 57 is suppressed, so that the durability of the belt 164 is improved.

  1 and 7, the first crankcase 2a and the first transmission case 56a are provided with a pair of left and right engine hangers 59 at a position overlapping the bank space S in a side view. In the engine hanger 59, a supported portion 59a formed with a through hole 59b into which a support shaft provided in the vehicle body frame is inserted is located above the cylinder 1a of the front bank B1 at a position overlapping the bank space S in a side view. The rear bank B2 is provided below the mating surface 1b1 between the cylinder 1b and the cylinder head 3b and at a position overlapping the cylinder 1b in the vertical direction. By providing the supported portion 59a of the engine hanger 59 at such a highly rigid position, the vibration characteristics to the vehicle body frame that supports the internal combustion engine E are improved, and the riding comfort of the motorcycle is improved.

  Referring to FIGS. 1 and 3, an intake device 60 disposed in the bank space S is coupled to an air cleaner (not shown) and the air cleaner downstream of the intake air, and is equipped with throttle valves 62a and 62b. A pair of throttle bodies 61a and 61b and a pair of connecting pipes coupled to the throttle bodies 61a and 61b on the upstream side of the intake air and coupled to the cylinder heads 3a and 3b on the bank space S side on the downstream side Insulators 64a and 64b.

  Intake passages 63a and 63b are formed in the throttle bodies 61a and 61b. The throttle valves 62a and 62b are disposed in the intake passages 63a and 63b to control the flow rate (intake amount) of intake air passing through the intake passages 63a and 63b. The air taken in through the air cleaner flows through an intake passage composed of passages 65a and 65b formed by intake passages 63a and 63b and insulators 64a and 64b, and further passes through an intake port 14 to the combustion chamber 13. Inflow. The throttle bodies 61a and 61b are connected to each other by a connecting member 67 and integrated.

  Further, a fuel injection valve 68 as an air-fuel mixture forming means for supplying fuel to the sucked air is attached to each throttle body 61a, 61b. The fuel injected from the fuel injection valve 68 toward the intake port 14 mixes with the intake air to form an air-fuel mixture, flows into the combustion chamber 13, and is ignited and burned by the spark plug 16 in the combustion chamber 13. The piston 5 that reciprocates due to the generated combustion pressure rotates the crankshaft 7 via the connecting rod 6.

  Referring to FIG. 9A, insulators 64a and 64b made of a rubber-like elastic material, for example, synthetic rubber, are fitted with fitting portions 61a1 and 61b1 constituted by the downstream ends of the throttle bodies 61a and 61b. It has upstream ends 64a1 and 64b1 that form fitting holes 66a and 66b.

  The central axes L2a and L2b of the intake passages 63a and 63b and the central axes L3a and L3b of the fitting holes 66a and 66b in the fitting portions 61a1 and 61b1 are a specific plane P0 that bisects the bank angle θ1, and in this embodiment, the bank angle θ1. Is inclined with respect to a specific plane P0 that bisects the image. In this embodiment, both the central axes L2a, L3a; L2b, L3b substantially coincide. Further, downstream end openings 63a1 and 63b1 of the intake passages 63a and 63b are formed by the downstream end opening edges 61a2 and 61b2 of the fitting parts 61a1 and 61b1, and are fitted by the upstream end opening edges 64a2 and 64b2 of the insulators 64a and 64b. Upstream end openings 66a1 and 66b1 of the holes 66a and 66b are formed.

  The downstream end openings 63a1, 63b1 are on the intake passages 63a, 63b side with respect to the first planes P1a, P1b perpendicular to the specific plane P0 and in contact with the downstream end openings 63a1, 63b1, and the upstream end openings 66a1, 66b1 The second flat surfaces P2a and P2b that are orthogonal to the specific plane P0 and in contact with the upstream end openings 66a1 and 66b1 are on the fitting holes 66a and 66b side. 9B and 9C, the insulators 64a and 64b include only a part of the upstream end portions 64a1 and 64b1, and the downstream end opening edge portions 61a2 and 61b2 are parallel to the specific plane P0. Guide portions 69a and 69b having guide surfaces 69a1 and 69b1 intersecting with the third planes P3a and P3b in contact therewith are provided.

  In this embodiment, at least the fitting portions 61a1 and 61b1 or the central axes L2a and L2b with respect to the insulators 64a and 64b, and further, the entire intake passages 63a and 63b and the entire throttle bodies 61a and 61b face upstream. Are inclined so as to approach the specific plane P0. In other words, the central axes L2a, L3a; L2b, L3b are, in a side view, the acute angles θ2a, θ3a; θ2b, θ3b from the cylinder axes L1a, L1b to the central axes L2a, L3a; L2b, L3b are the cylinder axes L1a. , L1b to the specific plane P0 is inclined so as to be larger than the acute angles θ4a, θ4b. The fuel injection valve 68 is disposed so as to sandwich the intake passage with the valve operating chamber 20. When the throttle bodies 61a and 61b are assembled to the insulators 64a and 64b from a direction parallel to the specific plane P0, the fitting portions 61a1 and 61b1 are guided to the fitting holes 66a and 66b while being in contact with the guide surfaces 69a1 and 69b1. The two throttle bodies 61a and 61b, which are connected and integrated with each other in advance by a connecting member 67 (see FIG. 1) by the guide portions 69a and 69b, respectively connect the fitting portions 61a1 and 61b1 to the respective fitting holes 66a and 66b. To guide.

  Each guide part 69a, 69b protrudes in a direction away from the fitting holes 66a, 66b and in a direction opposite to the assembling direction along the specific plane P0 with respect to the fitting holes 66a, 66b. The guide surfaces 69a1 and 69b1 are inclined with respect to both the central axes L2a and L3a; L2b and L3b, and are substantially formed by a part of a cylindrical surface or a conical surface.

  In the insulators 64a and 64b, guide portions 69a and 69b are provided in the distant portions 64a4 and 64b4 as one of the proximate side and the distant side with respect to the bank space S or the specific plane P0. The fuel injection valve 68 is attached to the throttle bodies 61a and 61b at positions corresponding to the close-side portions 64a3 and 64b3 as the other portion on the side and the far side. Further, the guide portions 69a and 69b and the fuel injection valve 68 are in positions that overlap each other at positions in the direction of the central axes L2a and L2b of the intake passages 63a and 63b.

  Referring to FIG. 1, an exhaust device that discharges combustion gas to the outside as exhaust gas is coupled to connecting portions 3a2 and 3b2 of cylinder heads 3a and 3b on the opposite side of the bank space S across the banks B1 and B2. An exhaust pipe (not shown) is provided, and exhaust gas that has passed through the exhaust port 15 is exhausted to the outside through the exhaust pipe.

  The air from the secondary air supply device 70 provided in each head cover 4a, 4b is introduced into the exhaust port 15 of each bank B1, B2. The secondary air supply device 70 that supplies air into the exhaust gas in order to oxidize HC and CO in the exhaust gas and purify the exhaust gas has the same structure in both banks B1 and B2. The secondary air supply device 70 in the front bank B1 will be described.

  Referring to FIG. 6B, the secondary air supply device 70 includes a housing 71 and a reed valve 72 accommodated in the housing 71. The housing 71 includes a body 71a formed integrally with the head cover 4a and a cover 71b coupled to the body 71a with the reed valve 72 interposed therebetween.

  The cover 71b is formed with an introduction port 73 through which air is introduced via a conduit (not shown) connected to the air cleaner, and the body 71a is formed with a lead-out port 74. The outlet port 74 is formed in the cylinder head 3 a and communicates with an air supply passage 75 that opens to the branch port 15 b of the exhaust port 15. In order to connect the outlet port 74 and the air supply passage 75, the body 71a is integrally formed with a tubular protruding portion 71a1 that forms the outlet 74a of the outlet port 74, and the protruding portion 71a1 is formed in the body of the cylinder head 3a. It is inserted into the inlet 75a of the air supply passage 75 that opens to the mating surface 3a3 with 71a. A connection portion between the outlet 74a and the inlet 75a is sealed by an annular seal member 76 provided between the body 71a1 and the mating surface 3a3 around the protrusion 71a1. The seal member 76 may be integrally formed with a gasket 77 interposed between the mating surfaces of the cylinder head 3a and the head cover 4a. Thus, since the outlet port 74 and the air supply passage 75 are connected by the protrusion 71a1 formed integrally with the body 71a, a conduit for connecting the outlet port 74 and the air supply passage 75 becomes unnecessary. The number of parts and cost are reduced.

  3 and 10, the lubrication system of the internal combustion engine E is a dry sump lubrication system, and includes an oil tank 48, a feed pump 81 that discharges the lubricating oil sucked from the oil tank 48 through the strainer 95, A water-cooled oil cooler 96 that cools the lubricating oil discharged from the feed pump 81, an oil filter 97, a scavenging pump 82 that collects the lubricating oil after lubricating each lubricating portion of the internal combustion engine E, and these lubricants It is comprised from many oil paths which guide lubricating oil between system members.

  An oil pump 80, which is an auxiliary machine of the internal combustion engine E, includes a feed pump 81 and a scavenging pump 82, both of which are trochoid pumps. The feed pump 81 includes a drive shaft 83 arranged in parallel to the rotation center line L0, a first pump body 84 configured by a part of the first crankcase 2a, and a drive shaft 83 that is rotationally driven by the pump chamber. A scavenging pump 82, which houses a rotor 87 to be formed and is coupled to the first pump body 84. The scavenging pump 82 has a drive shaft 83 common to the feed pump 81, a second pump body 85, A second pump cover 86 that accommodates a rotor 88 that is rotated by a drive shaft 83 to form a pump chamber and is coupled to a second pump body 85 is provided.

  The drive shaft 83 is coupled with a driven sprocket 90 as a driven rotating body over which a chain 89 (see also FIG. 7) as an endless transmission band is stretched between the drive sprocket 32c (see FIG. 2). Is driven to rotate by the power of the crankshaft 7 transmitted through the auxiliary gear transmission mechanism T3 constituted by the sprockets 32c and 90 and the chain 89. Further, the first pump body 84 is formed with a suction port 91 and a discharge port 92 (see FIG. 3) of the feed pump 81, and the second pump body 85 is formed with a suction port 93 of a scavenging pump 82, A discharge port 94 of the scavenging pump 82 is formed in the second pump cover 86.

  As shown in FIG. 3, the oil pump 80 is disposed between the cylinder 1a tilted forward and the lowest part L4 of the rotation locus of the crankshaft 7 in the vertical direction. Therefore, in this embodiment, at least the drive shaft 83 and the lowest part L4 are arranged so as to overlap at a position in the vertical direction. Thus, the distance between the oil pan portion 17 and the crankshaft 7 formed by the bottom portions 2a3 and 2b3 (see FIG. 8) of the crankcase 2 and where the lubricating oil after lubricating each lubricating portion of the internal combustion engine E gathers is reduced. Therefore, the internal combustion engine E can be downsized in the vertical direction.

  Referring to FIGS. 3, 7 and 10, the lubricating oil in the oil tank 48 is sucked into the bottom portions 2a3 and 2b3 of the first crankcases 2a and 2b below the vicinity of the lowest portion L4 through the strainer 95. A suction oil passage K1 that leads to the port 91 and a discharge oil passage K2 that guides the lubricating oil discharged through the discharge port 92 to the oil cooler 96 and the oil filter 97 downstream thereof are provided. The first pump body 84 branches from a discharge oil passage K2 downstream of the check valve 98 and a check valve 98 that is disposed in the discharge oil passage K2 and permits the flow of lubricating oil to the oil cooler 96 and the oil filter 97. A relief oil passage K3 that opens to the suction port 91 and a relief valve 99 disposed in the relief oil passage K3 are provided. The relief valve 99 is disposed across the first and second pump bodies 84 and 85. As described above, the first pump body 84 is provided with the check valve 98, the relief oil passage K3, and the relief valve 99, so that the oil pump 80 includes two pump bodies 84 and 85 and one pump cover 86. Since the housing structure is adopted, the housing structure of the oil pump 80 including the feed pump 81 and the scavenging pump 82 is simplified, and the oil pump 80 is reduced in size and weight. Further, the relief oil passage K3 opens to the suction port 91, and the lubricating oil flowing through the relief oil passage K3 is directly returned to the suction port 91, so that the oil pump 80 can be reduced in size and weight in this respect as well. Become. Further, the downsizing of the oil pump 80 increases the degree of freedom in layout of members disposed around the oil pump 80.

  The lubricating oil that has been cleaned by passing through the oil filter 97 flows into the main oil passage K4 provided in the first crankcase 2a at the bottom 2a3. Referring also to FIG. 2, the first crankcase 2a is provided with an oil passage K5 that guides the lubricating oil in the main oil passage K4 to the annular oil passage K6a that surrounds the slide bearing 8 and is provided in the bearing portion 2a1. The second crankcase 2b communicates with one downstream end K4a branched downstream of the main oil passage K4 so that the lubricating oil in the main oil passage K4 surrounds the slide bearing 9 and is provided in the bearing portion 2b1. An oil passage K7 that leads to K6b is provided, and the crankcase cover 45 communicates with the other downstream end K4b (see FIG. 7) of the main oil passage K4 so that the lubricating oil in the main oil passage K4 is oil for the crankshaft 7. An oil path K8 leading to the path K9 is provided. The open end K8a of the oil passage K8 is closed by the hydraulic sensor 100. As a result, since the hydraulic sensor 100 also serves as a plug for the oil passage K8, the space around the crankcase cover 45 to which the hydraulic sensor 100 is attached can be used more efficiently than when the hydraulic sensor 100 and the plug are provided separately. Thus, the layout of the parts is simplified.

  The oil passage K9 provided in the crankshaft 7 is provided along the rotation center line L0 from the shaft end surface of the shaft end portion 7a, and guides the lubricating oil in the oil passage K8 from the inside of the crankshaft 7 to the large end portion of the connecting rod 6. .

  Referring to FIG. 7, the cylinders 1a and 1b and the cylinder heads 3a and 3b of the banks B1 and B2 receive the lubricating oil of the annular oil passage K6a through the oil passage K10 provided in the first crankcase 2a. Oil passages K11 and K12 leading to the shaft 27 are provided. Since the oil passages and lubrication structures in the members in the valve operating chambers 20 of both banks B1, B2 are the same, the explanation will focus on the oil passages and lubrication structures in the front bank B1.

  Referring to FIGS. 6A and 8, the oil passage of the cylinder head 3a is provided inside the cam holder portion 29a. In the cam holder portion 29a, the oil passage K12 has a downstream portion K12b that extends in a straight line inclined to the cylinder axis L1a and penetrates the holding hole 29a1 with respect to the upstream portion K12a extending in parallel to the cylinder axis L1a. It has an end K12c that opens to a top surface 29a3 that is a surface facing the head cover 4a in the axial direction A1. The end K12c is closed by a bolt 41 that extends parallel to the cylinder axis L1a and is screwed into the screw hole 29a4 of the cam holder portion 29a. In this state, the shaft 41b of the bolt 41 is neither coaxial nor parallel to the central axis of the end K12c and intersects the end K12c.

  Lubricating oil in the oil passage K12 is provided inside the intake rocker arm shaft 27 and guided to an oil passage K13 that opens to a support surface 27c on which the intake rocker arm 25 slides. A portion of the lubricating oil from the oil passage K13 lubricates the sliding portion between the intake rocker arm shaft 27 and the intake rocker arm 25, and the remainder of the lubricating oil from the oil passage K12 is a jet outlet K14 provided in the intake rocker arm 25. The fuel is injected into the valve operating chamber 20 from (see FIG. 4). The oil droplets of the lubricating oil injected from the ejection port K14 flow from an oil hole K15 formed in the exhaust rocker arm 26 to lubricate the sliding portion between the exhaust rocker arm 26 and the exhaust rocker arm shaft 28, and further, the intake cam 23 and Lubricating portions within the valve operating chamber 20 such as sliding portions of the exhaust cam 24, the intake rocker arm 25, and the exhaust rocker arm 26, bearings 30 and 31, and the like are lubricated. The bearing 31 is also lubricated by the lubricating oil that has flowed from the oil hole K16 provided in the cam holder portion 29b, out of the lubricating oil injected from the ejection port K14.

  The lubrication oil after lubricating each lubrication point in the valve train chamber 20 is formed in the cylinder head 3a, the cylinder 1a and the first crankcase 2a, and is a chain chamber 18 (which is constituted by a cavity in which the chain 34a is disposed. 2), and returns to the crank chamber 10.

  Referring to FIGS. 3, 7, and 10, in the crank chamber 10, the lubricating oil after lubricating each lubricating portion such as the sliding portion of the internal combustion engine E gathers in the oil pan portion 17, and the oil pan portion 17 It flows into the guide part 17a provided near the lowest part. At the bottom 2a3 of the first crankcase 2a, a recovery oil passage K17 that guides lubricating oil from the guide portion 17a pumped up through the strainer 101 to the suction port 93 of the scavenging pump 82 is provided in the left-right direction substantially parallel to the suction oil passage K1. It extends and is provided on the same horizontal plane. As described above, the intake oil passage K1 and the recovery oil passage K17 are arranged substantially in parallel on the same horizontal plane, whereby the internal combustion engine E can be downsized in the vertical direction.

  Lubricating oil in the discharge port 94 is disposed in the crank chamber 10 and passes through a discharge oil passage K18 formed by a conduit 103 inserted into an insertion hole 102 provided in the first crankcase 2a, and then enters the crankcase cover 45. It is led to a drain oil passage K19 that is provided and opens to the upper space in the oil tank 48. As a result, the discharge oil passage K18 that allows the scavenging pump 82 and the oil tank 48 to communicate with each other is formed by the conduit 103, so that the degree of freedom of layout of the scavenging pump 82 is increased.

  In the oil tank 48, in the gas-liquid separation chamber formed by arranging a plurality of baffle plates, the air containing the blow-by gas sucked by the scavenging pump 82 together with the lubricating oil recovered from the crank chamber 10 is lubricating oil. Separated from. Then, the lubricating oil from which the air has been separated is sucked into the feed pump 81 through the suction oil passage K1.

  Referring to FIGS. 3, 7, and 11, the discharge port 92 of the feed pump 81 has an air vent that enters the lubrication system and discharges air mixed in the lubricant when the internal combustion engine E is stopped and the oil is changed. A passage 104 communicates. The air vent passage 104 is formed in the pump body 84, communicates with the uppermost portion of the discharge port 92 and extends in the horizontal direction, and rises upward from the passage 105 in the chain chamber 18 or the auxiliary machinery chamber 47. And a passage 106. The rising passage 106 is formed by an air vent pipe 107 whose one end is inserted into the passage 105. A discharge port 108 for discharging air to the chain chamber 18 or the auxiliary machine chamber 47 is formed at the tip of the ascending passage 106. The ascending passage 106 accommodates a ball 110 as a valve body held by the holding portion 109 of the ascending passage 106, and the ball 110 is a discharge port 108 formed in the plug 111 that closes the distal end portion of the air vent pipe 107. Can be closed. For this purpose, the air vent pipe 107 is provided with an engaging portion 112 that can engage and disengage the ball 110 as a holding portion 109. While the ball 110 is held by the engaging portion 112, air is allowed to be discharged from the discharge port 92 to the chain chamber 18 or the auxiliary machine chamber 47, while air is prevented from entering the discharge port 92 from the discharge port 108. Stop. When the lubricating oil from the discharge port 92 flows into the air vent passage 104, the ball 110 is pushed up by the hydraulic pressure and seated on the plug 111 to seal the discharge port 108. The ascending passage 106 may be formed in the first crankcase 2a itself constituting the first pump body 84 together with the passage 105.

  As a result, air mixed in the lubricating oil is easily discharged, and leakage of the lubricating oil from the air vent pipe 107 is prevented. Further, as indicated by a two-dot chain line in FIGS. 7 and 11, the lubricating oil is directed toward the AC generator 46 by communicating with the air vent pipe 107 through the rising passage 106 between the holding portion 109 and the discharge port 108. An ejection port 113 for ejecting may be provided. Thus, the AC generator 46 (see FIG. 2) can be cooled by the lubricating oil injected from the injection port 113 while the ball 110 pushed up by the hydraulic pressure is seated on the plug 111 and the discharge port 108 is sealed. it can.

  Referring to FIGS. 3 and 10, in the crank chamber 10, an overflow passage 115 that guides the lubricating oil overflowing from the oil tank 48 to the oil pan portion 17 is provided at the rear portion that is a portion near the oil tank 48. Two grooves 115a and 115b formed on the crankcases 2a and 2b and opened on the mating surfaces thereof are configured. A breathing passage 116 opened to the crank chamber 10 is formed at the uppermost portion of the overflow passage 115 by a notch provided in the first crankcase 2a, and the overflow passage 115 is blocked by the lubricating oil by the breathing passage 116. Is prevented.

  Referring to FIG. 3, a breather chamber 120 provided in the head cover 4a of the front bank B1 and communicating with the uppermost portion of the valve operating chamber 20 is coupled to a main body 121 constituted by a part of the head cover 4a, and the main body 121. The cover 122 is formed. The main body 121 is located at a position away from the mating surface of the head cover 4a with the cylinder head 3a or the gasket 77, and as much as possible within the bank space S within a range that does not interfere with the guide portion 69a of the insulator 64a in the assembly direction. It protrudes like a bowl. For this reason, since the seal length by the gasket 77 can be shortened as compared with the case where the breather chamber is formed by the joint of the cylinder head and the head cover, the sealing performance at the mating surface of the head cover 4a and the cylinder head 3a. Will improve. Furthermore, since the breather chamber 120 is formed so as to protrude into the bank space S, the volume of the breather chamber 120 can be increased. In addition, since it protrudes into the bank space S as much as possible without interfering with the intake device 60, space efficiency is improved and the degree of freedom in layout is increased.

  3 and 10, the cooling system of the internal combustion engine E includes a cooling water pump 130 for pumping cooling water, and cooling water jackets W2, W3, W5 formed in the cylinders 1a, 1b and the cylinder heads 3a, 3b. , W6, the radiator R, the thermostat 152 for controlling the flow and blocking of the cooling water to the radiator R according to the warm-up state of the internal combustion engine E, and the conduits and pipe joints that form the cooling water passage outside the engine body It is comprised from the piping group which consists of etc.

  The cooling water pump 130 includes a drive shaft 131 coaxial with the drive shaft 83 of the oil pump 80, an impeller 132 that is driven to rotate by the drive shaft 131, and a part of the crankcase cover 45, and can rotate the drive shaft 131. And a pump cover 134 coupled to the pump body 133. In the pump cover 134, an inlet port 135 into which cooling water that has been radiated by the radiator R and cooled to flow in flows, a bypass port 136 into which cooling water from a bypass passage W7 described later flows, and cooling that is pumped by the impeller 132. And an outlet port 137 through which water flows out. The outlet port 137 formed in cooperation with the crankcase cover 45 is connected to the outlet port 137 and a pipe joint 138 that is almost entirely inserted into a supply passage W1 formed by a hole provided in the cylinder 1a. , Communicated with the supply passage W1. In this way, the cooling water immediately after being discharged from the cooling water pump 130 can be guided to the cooling water jacket W2 of the cylinder 1a without using a hose, so that the piping of the cooling water is simplified and made compact. Is done.

  The drive shaft 131 is drivingly connected to the drive shaft 83 coaxially with the drive shaft 83 via a bolt 139 as a shaft joint, and is rotatably supported by the pump body 133 by a bearing 140. Referring also to FIG. 11, the bolt 139 is for coupling the driven sprocket 90 to the drive shaft 83, and the head 139a of the bolt 139 is formed in a prismatic shape, in this embodiment a hexagonal prism shape, The head 139 a is fitted into a fitting hole 141 having the same shape formed in the drive shaft 131, so that the drive shaft 131 is coupled to rotate integrally with the drive shaft 83. In this way, the bolt 139 that couples the driven sprocket 90 to the drive shaft 83 also serves as a shaft coupling, so the number of parts is reduced. Further, the drive shaft 131 is supported by a drive shaft 83 that is rotatably supported by the pump bodies 84 and 85 of the oil pump 80 via bolts 139 at the end of the shaft. Therefore, the cooling water pump 130 can be downsized.

  3 and 10, in the cooling system, the cooling water from the outlet port 137 of the cooling water pump 130 flows into the cooling water jacket W2 of the cylinder 1a of the front bank B1 through the supply passage W1, and the cylinder 1a. Is cooled and then flows into the cooling water jacket W3 of the cylinder head 3a to cool the cylinder head 3a and the spark plug 16. Thereafter, the cooling water flows from the cooling water jacket W3 through the cooling water passage W4 formed by the conduit 151 into the cooling water jacket W5 of the rear bank B2 to cool the cylinder 1b, and then the cooling water jacket W6 of the cylinder head 3b. Then, after the cylinder head 3b and the spark plug 16 are cooled, they flow into the thermostat 152 attached to the cylinder head 3b.

  In the cooling water jacket W3 of the cylinder head 3a, as shown in FIG. 5, when the cooling water flows from the exhaust port 15 side to the intake port 14 side, it branches upstream and passes through the vicinity of the spark plug 16 Further, after flowing between the pair of branch ports 14a and 14b of the intake port 14, a branch passage W3a for cooling water that merges downstream is formed. By this branch passage W3a, the stagnation of the cooling water in the vicinity of the spark plug 16 is eliminated, and the cooling of the spark plug 16 is promoted. The structure of the cooling water jacket W6 of the cylinder head 3b is the same as the structure of the cooling water jacket W3.

  Referring to FIGS. 1 and 7, when the internal combustion engine E is warmed up (as shown), the thermostat 152 closes the main valve 152a and opens the bypass valve 152b, so that the thermostat 152 flows into the thermostat 152. The cooled water flows through a bypass passage W7 formed by a pipe joint 153 connected to the bypass outlet 152c of the thermostat 152 and a conduit 154 connecting the bypass port 136, and is sucked into the cooling water pump 130. Further, after the warm-up of the internal combustion engine E is completed, in the thermostat 152, the main valve 152a is opened and the bypass valve 152b is closed, so that the cooling water flowing into the thermostat 152 flows out from the outlet 152d of the thermostat 152. Then, after flowing into the radiator R and radiating heat from the radiator R to become a low temperature, it flows through a cooling water passage formed by a conduit connecting the radiator R and the inlet port 135 and is sucked into the cooling water pump 130.

  Thus, the upstream end W7a of the bypass passage W7 formed by the pipe joint 153 extends downward from the cylinder head 3b, and the bypass passage W7 is disposed at a position corresponding to the bottom portions 2a3 and 2b3 of the crankcase 2. Accordingly, the pipe joint 153 and the conduit 154 are arranged in a compact manner, and the air in the bypass passage W7 is easily released.

  Referring to FIGS. 1 and 4, the oil cooler 96 is led from the supply passage W <b> 1 through a cooling water passage formed by a conduit 155, and the cooling water after cooling the lubricating oil is supplied to the oil cooler 96. And a return passage formed by a conduit 157 connected to a pipe joint 156 (see also FIG. 7) connected to the cylinder head 3b portion in the vicinity of the thermostat 152, it is returned to the inlet side of the thermostat 152. As a result, the cooling water that has become a high temperature by cooling the lubricating oil immediately flows into the thermostat 152 without passing through the respective cooling water jackets W2, W3, W5, W6, so that the cylinders 1a, 1b and the cylinder heads 3a, 3b Cooling efficiency is improved.

  Referring to FIGS. 1 and 2, the power transmission device is a gear type of a transmission M arranged from the right to the rear of the internal combustion engine E, and the power of the crankshaft 7 transmitted via the transmission M. A centrifugal clutch C that performs transmission and disconnection to the transmission mechanism R1, a final reduction gear, and a transmission case 56 are provided. Here, the final reduction gear is composed of a gear transmission mechanism R1 and a chain transmission mechanism R2.

  The transmission M includes a drive pulley 161 including a variable pulley that is rotatably coupled to a shaft end portion 7b that also serves as a drive shaft 160 that is driven by the internal combustion engine E, and a driven pulley that is rotatably supported by the output shaft 165. A driven pulley 163 composed of a variable pulley supported rotatably on the shaft 162 and connected to the output shaft 165 via the centrifugal clutch C so as to rotate integrally therewith, and an endless V that is stretched between the driving pulley 161 and the driven pulley 163 A belt 164 formed of a belt, an output shaft 165 rotatably supported by the rear portion 56a2 of the first transmission case 56a and the rear portion 2a2 of the first crankcase 2a, and a winding radius of the belt 164 in the driving pulley 161 and the driven pulley 163 Transmission ratio control means for changing

  The drive pulley 161 is a fixed pulley half 161a coupled to the shaft end 7a (drive shaft 160) so as not to move relative to the shaft end 7a, and a movable pulley movable in the rotation center line direction (axial direction) with respect to the fixed pulley half 161a. It consists of a half body 161b. The driven pulley 163 includes a fixed pulley half 163a that can rotate integrally with the driven shaft 162, and a movable pulley half 163b that is connected to the driven shaft 162 via a torque cam mechanism.

  The transmission ratio control means includes a plurality of centrifugal weights 167 whose positions in the axial direction are changed by a cam plate 166 fixed to the drive shaft 160, and a belt disposed on the movable pulley half 163b coaxially with the driven shaft 162. And a spring 168 for applying a resilient force in the direction of tightening 164. In the drive pulley 161, each centrifugal weight 167 moves in the radial direction and moves in the axial direction according to the centrifugal force generated according to the rotational speed of the crankshaft 7, so that the movable pulley is pressed against the centrifugal weight 167. The half body 161b moves in the axial direction, and the winding radius is changed. Due to the change in the tension of the belt 164 generated at this time, in the driven pulley 163, the movable pulley half 163b moves in the axial direction against or against the elastic force of the spring 168, and is wound around. The radius is changed. As a result, the gear ratio of the transmission M is automatically and continuously changed according to the engine speed.

  The torque cam mechanism includes a cam groove 170 formed in a sleeve 169 that is rotatably supported by the driven shaft 162 while the movable pulley half 163b is fixed, and is fixed to the driven shaft 162 and engages with the cam groove 170. And a driven pulley in a direction in which the belt 164 is tightened according to the relative rotation between the fixed pulley half 163a and the movable pulley half 163b when the load acting on the rear wheel of the motorcycle increases. The half 163b is moved.

  The spring 168 disposed between the input member 181 of the centrifugal clutch C that can rotate integrally with the driven shaft 162 and the movable pulley half 163b is supported by at least one of its both ends by a spring receiving member having a low coefficient of friction. Is done. In this embodiment, the spring receiving member that supports the end portion 168a of the spring 168 near the movable pulley half 163b is disposed so as to be overlapped in the axial direction and is made of two synthetic resin members having a low coefficient of friction. A double washer 172 made of washers is used. Further, the spring receiving member may be constituted by a thrust bearing instead of the double washer 172.

  Thus, when the movable pulley half 163b rotates relative to the fixed pulley half 163a by supporting the spring 168 by the spring receiving member having a low friction coefficient, the spring 168 is moved to the movable pulley half 163a. Since the fluctuation of the elastic force of the spring 168 is prevented or suppressed due to the frictional force between the belt and the driven pulley, the rotation from the belt to the driven pulley is prevented. Torque transmission performance is improved.

  The centrifugal clutch C includes an input member 181 that supports the centrifugal weight 183 so as to be swingable, and an output member 182 that is coupled to the output shaft 165 so as to be integrally rotatable, and the driven shaft 162 has an idling rotational speed of the internal combustion engine E. When rotating beyond the corresponding rotation speed, the input member 181 and the output member 182 are connected together via the centrifugal weight 183 that is blown off by the centrifugal force and presses the output member 182.

  The gear transmission mechanism R1 includes an input gear 191 of an output shaft 165, an intermediate gear 192 that meshes with the input gear 191 and an output gear 193. The output shaft is rotatably supported by the first crankcase 2a and the first and second transmission cases 56a and 56b, and both gears 192 and 193 are rotatably supported by the first crankcase 2a and the first transmission case 56, respectively.

  A drive sprocket 195 around which a drive chain is wound is coupled to an output take-out shaft 194 that is coupled to the output gear 193 so as to be integrally rotatable. Further, the swing arm 200 that supports the rear wheel so as to be rotatable at the rear end portion is swingably supported by the pivot shaft 201 coaxial with the output extraction shaft 194 at the front end portion. The pivot shaft 201 includes a pair of left and right first and second pivot shafts 201a and 201b. The first pivot shaft 201a is coupled to the rear end portion of the first crankcase 2a, and the second pivot shaft 201b is The first transmission case 56a is coupled to the rear end of the first transmission case 56a.

Next, the cooling structure of the transmission M will be described.
The cover coupled to the second transmission case 56b and the second transmission case 56b form an air guide chamber 174 that guides the cooling air into the transmission chamber 57. The cover 173 is provided with an intake 175 for introducing outside air into the air guide chamber 174. An intake port 175 formed by a duct 176 integrally formed with the cover 173 has an outlet port 175b that opens forward from an inlet port 175a that opens rearward. The intake port 175 is provided between the drive shaft 160 and the driven shaft 162, and is provided at a position overlapping the driven pulley 163 in a side view, and the outlet 175b is positioned at substantially the center between the drive pulley 161 and the driven pulley 163. . The cooling air sucked by the cooling fan 177 constituted by the fixed pulley half 163a of the driven pulley 163 flows into the air guide chamber 174 through the intake port 175, and then moves from the front to the rear in the air guide chamber 174. Then, it passes through the filter element 178 and flows into the transmission chamber 57 from the inlet 179 formed in the cover 173 toward the fixed pulley half 163a in the axial direction of the driven shaft 162.

  Since the driving pulley 161 and the driven pulley 163 are disposed close to each other, in the belt-type transmission M in which the distance between the driving shaft 160 and the driven shaft 162 is relatively short, between the driving shaft 160 and the driven shaft 162. Since the intake 175 can be formed by utilizing the space between the drive shaft 160 and the driven shaft 162, the second transmission case 56b or the cover 173 is provided to provide the intake. Is prevented from becoming large. Further, since the cooling air flows into the transmission chamber 57 toward the driven pulley 163, the cooling of the driven pulley 163 is promoted.

  The boss portion of the fixed pulley half 161a of the drive pulley 161 is provided with a cooling air passage 161e including a large number of through holes positioned radially inward from the belt 164 having the minimum winding radius. As a result, the cooling air is guided through the cooling air passage 161e to the space between the first transmission case 56a adjacent to the crankcase 2 and the driving pulley 161, so that the back surface of the stationary pulley half 161a is cooled, and the crankcase 2 Cooling of the fixed pulley half 161a, which is a portion of the drive pulley 161 adjacent to the front, is promoted.

  Further, the first transmission case 56a includes a crankcase 2 that is substantially in the middle between the driving pulley 161 and the driven pulley 163 and that is opposed to the first crankcase 2a and near the outer periphery of the centrifugal clutch C. In the space between the transmission case 56 and the transmission case 56, there is provided an exhaust port 56a3 that directs the crankcase 2 and through which cooling air flows out of the transmission chamber 57. Thereby, in the transmission chamber 57, the centrifugal clutch C is cooled by the cooling air flowing toward the exhaust port 56a3, and the crankcase 2 is cooled by the cooling air flowing out from the exhaust port 56a3.

Next, operations and effects of the embodiment configured as described above will be described.
The central axes L2a, L2b; L3a, L3b of the intake passages 63a, 63b in the fitting portions 61a1, 61b1 of the throttle bodies 61a, 61b and the fitting holes 66a, 66b of the insulators 64a, 64b are inclined with respect to the specific plane P0. The downstream end openings 63a1, 63b1 of the fitting portions 61a1, 61b1 of the throttle bodies 61a, 61b are on the intake passages 63a, 63b side with respect to the first planes P1a, P1b, and the insulators 64a, 64b are fitted. The upstream end openings 66a1 and 66b1 of the holes 66a and 66b are on the fitting holes 66a and 66b side with respect to the second planes P2a and P2b, and the third planes P3a and P3b are formed only on a part of the upstream ends 64a1 and 64b1. When the body is assembled to the insulators 64a and 64b from the direction parallel to the specific plane P0, the fitting portions 61a1 and 61b1 are fitted to the guide surfaces 69a1 and 69b1. Is guided to the fitting holes 66a and 66b.
As a result, the downstream end openings 63a1 and 63b1 of the throttle bodies 61a and 61b are flow passage cross sections of the intake passages 63a and 63b with respect to the first planes P1a and P1b (the intake passage 63a in a plane orthogonal to the central axes L2a and L2b). In the same manner, the upstream end openings 66a1 and 66b1 of the insulators 64a and 64b are flow passage sections of the passages 65a and 65b of the insulators 64a and 64b with respect to the second planes P2a and P2b. Since it is inclined in a direction approaching (the cross section of the passages 65a and 65b in the plane orthogonal to the central axes L3a and L3b), the opening area of the downstream end openings 63a1 and 63b and the opening area of the upstream end openings 66a1 and 66b1 are respectively The area in the cross section of the flow path can be approached, and the throttle bodies 61a and 61b and the insulators 64a and 64b can be reduced in size.
The guide portions 69a and 69b are provided only in a part of the upstream end portions 64a1 and 64b1 of the insulators 64a and 64b. When the throttle bodies 61a and 61b are assembled to the insulators 64a and 64b, the throttle bodies 61a and 61b are fitted. Since the portions 61a1 and 61b1 are guided by the fitting holes 66a and 66b while being in contact with the guide portions 69a and 69b, the downstream end openings 63a1 and 63b1 of the throttle bodies 61a and 61b and the upstream end openings 66a1 and 66b1 of the insulators 64a and 64b. However, even when inclined with respect to the first planes P1a and P1b and the second planes P2a and P2b, respectively, the assembly of the throttle bodies 61a and 61b to the insulators 64a and 64b is facilitated, and the guide portion 69a. 69b are provided only in a part of the upstream end portions 64a1 and 64b1, and the provision of the guide portions 69a and 69b prevents the insulators 64a and 64b from being enlarged. As a result, the guide parts 69a and 69b facilitate the assembly of the throttle bodies 61a and 61b to the insulators 64a and 64b, and the provision of the guide parts 69a and 69b increases the size of the insulators 64a and 64b. As a result, the throttle bodies 61a and 61b and the insulators 64a and 64b can be reduced in size compared with the prior art, and thus the intake device 60 can be reduced in size.

  The first throttle body 61a and the second throttle body 61b are integrally connected to each other, and the guide portions 69a and 69b are first and second guide portions 69a and 69b provided in the first and second insulators 64a and 64b, respectively. By being composed of 69b, the first and second throttle bodies 61a and 61b are guided together by the first and second guide portions 69a and 69b in a state where the first and second throttle bodies 61a and 61b are integrally connected. Is further improved.

  In each insulator 64a, 64b, guide portions 69a, 69b are provided in the distant portions 64a4, 64b4, and the fuel injection valve 68 is attached to the throttle bodies 61a, 61b at positions corresponding to the close portions 64a3, 64b3. As a result, when the throttle bodies 61a and 61b are assembled to the insulators 64a and 64b, the fuel injection valve 68 and the guide portions 69a and 69b do not interfere with each other, so that the throttle bodies 61a and 61b to the insulators 64a and 64b. At the time of assembly, the fuel injection valve 68 and the guide portions 69a and 69b do not interfere with each other, and good assembly properties are ensured.

  Further, the guide portions 69a and 69b and the fuel injection valve 68 are arranged so as to overlap each other at the positions in the direction of the central axes L2a and L2b of the intake passages 63a and 63b, thereby fuel injection to the insulators 64a and 64b. The valve 68 can be arranged compactly in the direction of the central axes L2a and L2b of the intake passages 63a and 63b.

  The guide portions 69a and 69b protrude from the fitting holes 66a and 66b in the direction along the central axis L3a and L3b or the specific plane P0 and away from the fitting holes 66a and 66b. Since the guide surfaces 69a1 and 69b1 can be enlarged along the assembly direction, when the throttle bodies 61a and 61b are assembled to the insulators 64a and 64b, the guide portions 69a and 69b are used from the early stage of the assembly process. Since the fitting portions 61a1 and 61b1 are guided, the assembling property is further improved.

  The valve operating device 21 of the internal combustion engine E swings into the intake rocker arm shaft 27 and the exhaust rocker arm shaft 28 held by the cam holders 29 provided in the cylinder heads 3a and 3b in the valve operating chamber 20, and both the rocker arm shafts 27 and 28, respectively. It is provided with an intake rocker arm 25 and an exhaust rocker arm 26 that are movably supported to open and close the intake valve 17 and the exhaust valve 18, and the bolt 37 has a rocker arm shaft 28 that is one of the rocker arm shafts 27 and 28 in the axial direction. By restricting the movement, the bolt 37 that couples the head covers 4a and 4b to the cylinder heads 3a and 3b serves as a restricting member that restricts the movement of the rocker arm shaft 28 in the valve operating chamber 20 in the axial direction. Used. As a result, since the bolt 37 also serves as a restricting member that restricts the movement of the rocker arm shaft 28, a dedicated member for restricting the movement of the rocker arm shaft 28 in the axial direction becomes unnecessary, and the number of parts is reduced.

  The bolt 37 includes a head portion 37a and a shaft portion 37b that abuts against the rocker arm shaft 28 in the axial direction. The head portion 37a presses the head covers 4a and 4b outside the valve operating chamber 20 and also operates the valve operating chamber 20. And the shaft portion 37b extends in the cylinder axial directions A1 and A2 from the contact surface 37c, so that the cylinder between the head covers 4a and 4b and the bolt 37 is provided. Since no space is formed in the axial directions A1 and A2, the head covers 4a and 4b can be brought close to the cam holder portion 29b in the cylinder axial directions A1 and A2, so that the head covers 4a and 4b can be moved in the cylinder axial direction A1. , A2 and the internal combustion engine E can be reduced in the cylinder axial directions A1 and A2.

  The rocker arm shaft 28 is formed with an insertion portion 28d into which a bolt 37 is inserted. The rocker arm shaft 28 is positioned on the cam holder portions 29a and 29b by the bolt 36, whereby the head covers 4a and 4b are coupled to the cylinder heads 3a and 3b. Then, the bolt 37 is inserted into the insertion portion 28d provided in the rocker arm shaft 28 where the insertion portion 28c is already positioned by the bolt 36 so as to align with the screw hole 29b4, and the head covers 4a and 4b are inserted into the bolt 37. Are coupled to the cylinder heads 3a and 3b. As a result, since the bolt 37 is inserted using the space where the rocker arm shaft 28 is disposed, there is no need to separately secure a portion through which the bolt 37 is inserted in the cylinder heads 3a and 3b. , 3b is reduced in size.

  The bolt 41 closes the head cover 4a, 4b to the cylinder head 3a, by closing the end K12c of the oil passage K12 for guiding the lubricating oil to the sliding portion between the intake rocker arm shaft 27 and the intake rocker arm 25 in the valve operating chamber 20. The bolt 41 coupled to 3b is used as a plug for closing the end K12c of the oil passage K12. As a result, since the bolt 41 also serves as a plug for the oil passage K12, a dedicated plug for closing the oil passage K12 becomes unnecessary, and the number of parts is reduced.

  Since the shaft portion 41b of the bolt 41 intersects the end portion K12c, the direction in which the end portion K12c of the downstream portion K12b extending linearly extends and the screwing direction of the bolt 41 need not be coaxial or parallel, and the end portion K12c Since the direction in which the bolt 41 extends and the direction in which the bolt 41 is screwed in is limited as much as possible, the degree of freedom in the layout of the oil passage K12 having the end K12c and the bolt 41 is increased.

Hereinafter, an embodiment in which a part of the configuration of the above-described embodiment is changed will be described with respect to the changed configuration.
Each of the first and second banks may be composed of a plurality of first cylinders and second cylinders. Further, the first and second cylinders may be integrally formed to constitute a cylinder block.
The specific plane P0 may be a plane that does not bisect the bank angle θ1.
The bolt that couples the head cover to the cylinder head may restrict at least one of the intake rocker arm shaft and the exhaust rocker arm shaft from moving in the axial direction.
The cam holder 29 may be formed of a member separate from the cylinder heads 3a and 3b, and may be integrally coupled to the cylinder heads 3a and 3b with bolts or the like.
The air-fuel mixture forming means may be a carburetor instead of the fuel injection valve 68. In this case, the throttle bodies 61a and 61b are constituted by the body of the carburetor.
The center axes L2a, L2b; L3a, L3b of the fitting portions 61a1, 61b1 and the center axes L2a, L2b; L3a, L3b of the fitting holes 66a, 66b may be inclined so that the acute angle is smaller than the acute angle. . In this case, guide portions 69a and 69b are provided in the portions closer to the bank space S or the specific plane P0 in the insulators 64a and 64b, and the fuel injection valve is located at a position corresponding to the portion on the far side in the insulators 64a and 64b. 68 is attached to the throttle bodies 61a and 61b.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a right side view showing a part of a transmission cover in a cross section in an internal combustion engine to which the present invention is applied, showing an embodiment of the present invention. It is the II-II sectional view taken on the line of FIG. FIG. 2 is a right side view of the internal combustion engine of FIG. 1, showing a part in cross-section when a part of the crankcase is removed. FIG. 4 is a view taken in the direction of arrow IV in FIG. 1 and showing a part in cross-section when the head cover is removed. FIG. 2 is a diagram visualizing a cooling water jacket, an intake port, and an exhaust port in a cylinder head of a front bank of the internal combustion engine of FIG. 1. 4A is a sectional view taken along the line VIA-VIA in FIG. 4 in a state where the head cover is coupled to the cylinder head, and FIG. 4B is a sectional view taken along the line VIB-VIB in FIG. FIG. FIG. 2 is a left side view showing a part in cross section in the internal combustion engine of FIG. 1. It is the VIII-VIII sectional view taken on the line of FIG. (A) is the principal part enlarged view of FIG. 3, (B) is the B section enlarged view of (A), (C) is the C section enlarged view of (A). It is the XX sectional view taken on the line of FIG. It is the XI-XI sectional view taken on the line of FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1a, 1b ... Cylinder, 2 ... Crankcase, 3a, 3b ... Cylinder head, 4a, 4b ... Head cover, 7 ... Crankshaft, 21 ... Valve-operating device, 22 ... Cam shaft, 27, 28 ... Rocker arm shaft, 29 ... Cam holder 34-37 ... bolts, 48 ... oil tanks, 61a, 61b ... throttle bodies 64a, 64b ... insulators, 69a, 69b ... guides, 81 ... feed pumps, 82 ... scavenging pumps,
E: Internal combustion engine, M: Transmission, C: Centrifugal clutch.

Claims (4)

A V-type internal combustion engine including an intake device disposed in a bank space between first and second banks constituting a V bank by arranging first and second cylinders in a V shape, In the V-type internal combustion engine, the apparatus includes a throttle body and an insulator having an upstream end portion that forms a fitting hole into which a fitting portion constituted by the downstream end portion of the throttle body is fitted.
A guide portion is provided only at a part of the upstream end portion, and when the throttle body is assembled to the insulator, the fitting portion is guided to the fitting hole while being in contact with the guide portion. V-type internal combustion engine.   The throttle body includes a first throttle body provided in the first bank and a second throttle body provided in the second bank, and the insulator includes a first insulator to which the first throttle body is assembled, and the A second insulator to which the second throttle body is assembled, the first and second throttle bodies are integrally connected to each other, and the guide portions are provided in the first and second insulators, respectively. 2. A V-type internal combustion engine according to claim 1, comprising a first guide portion and a second guide portion.   In the insulator, the guide portion is provided in one portion on the near side and the far side with respect to the bank space, and a fuel injection valve is provided at a position corresponding to the other portion on the near side and the far side in the insulator. The V-type internal combustion engine according to claim 1, wherein the V-type internal combustion engine is attached to the throttle body. 4. The V shape according to claim 1, wherein the guide portion protrudes in a direction away from the fitting hole along a central axis of the fitting hole. 5. Internal combustion engine.

Images