JP2008274863A - Air cooled v-type engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an air cooled V-type engine reducing the weight of each bank and enabling improvement of cooling effect. <P>SOLUTION: In the air cooled V-type engine, intake and exhaust rocker arms 71a, 72a; 71b, 72b of a first and a second banks B1, B2 are arranged in a V-shape on both sides of a valley part 11, and are arranged in a chevron shape in a plane view to put intake and exhaust push rods 44a, 45a ; 44b, 45b side end parts mutually close, each intake and exhaust push rods are put mutually close, both of an upper and lower ends of each pair of tubular rod covers 59, 60 storing the intake and the exhaust push rods respectively are supported by an upper and a lower support parts 74, 75 extending in the valley part 11 side form the upper and the lower end parts of the banks B1, B2, and a notch 6a enabling close arrangement of rod covers 59, 60 to each bank B1, B2 outer walls is provided on cooling fins 6 of each bank B1, B2. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  In the present invention, first and second banks each having a cylinder bore and arranged in a V shape so as to define a valley between them are connected to a crankcase that supports a crankshaft, and each bank Cooling fins are provided on the outer wall of each bank, and suction and exhaust valves are arranged in a V shape on the heads of the banks. A valve operating device for opening and closing the suction and exhaust valves is provided above the crankshaft. The camshaft driven from the crankshaft, the first suction, the exhaust cam follower and the second suction, the exhaust cam follower, and the first suction, the exhaust cam follower and the second suction, which are lifted and lowered by the suction of the camshaft and the exhaust cam, respectively. The first suction, the exhaust push rod and the second suction, the exhaust push rod, and the first suction and exhaust, respectively, which are connected to the exhaust cam follower and connected to the valley portions of the first and second banks, respectively. Push rod Beauty second intake, the upper end of the corresponding bank intake of the exhaust push rod, a first intake which connects respectively to the exhaust valve, the exhaust rocker arm and the second intake relates to an improvement in air-cooled engine that is constituted by the exhaust rocker arm.

Such an air-cooled V-type engine is already known as disclosed in Patent Document 1, for example.
JP-A-3-107515

  In such an air-cooled V-type engine, when each bank is cast, the rod chambers for accommodating the intake and exhaust push rods are integrally formed, so that each bank itself is enlarged, and at the corners of the rod chambers. Inevitably, a lot of meat was added, making it difficult to reduce the weight. In addition, since the portion of the cylinder bore of each bank facing the rod chamber cannot be exposed to the outside air, the air cooling effect is somewhat reduced.

  The present invention has been made in view of such circumstances, and an object of the present invention is to provide an air-cooled V-type engine capable of reducing the weight of each bank and improving the air-cooling effect.

  In order to achieve the above object, the present invention provides a crankcase for supporting a crankshaft with first and second banks each having a cylinder bore and arranged in a V shape so as to define a valley between them. In addition, a cooling fin is provided on the outer wall of each bank, and suction and exhaust valves are arranged in a V shape on the head of each bank. A camshaft disposed above the crankshaft and driven from the crankshaft, a first suction, an exhaust cam follower and a second suction, an exhaust cam follower that are moved up and down by the suction and exhaust cams of the camshaft, and the first Suction, exhaust cam follower and second suction, exhaust cam follower is connected to the lower end of the first and second banks, respectively, the first suction, exhaust push rod and second suction, exhaust push rod And these Air-cooled V-type consisting of 1 suction, exhaust push rod and 2nd suction, upper end of exhaust push rod with corresponding bank suction, 1st suction, exhaust rocker arm and 2nd suction, exhaust rocker arm respectively connected to exhaust valve In the engine, the suction and exhaust rocker arms of each bank are arranged in a letter C shape in plan view so that these suction and exhaust push rod side ends are close to each other, and the suction and exhaust push rods are mutually connected. The upper and lower ends of each pair of tubular rod covers that are close to each other and accommodate the suction and exhaust push rods are supported by the upper and lower support portions that project from the upper and lower ends of each bank to the valley side, respectively. The first feature is that the cooling fin of each bank is provided with a notch that allows the rod cover to be disposed close to the outer wall of each bank.

  According to the present invention, in addition to the first feature, each bank is formed by integrally forming a cylinder block having a cylinder bore and a cylinder head that supports the intake and exhaust valves, and the upper support is supported on the cylinder head. The lower support part is formed integrally with the cylinder block, and the upper end and the lower end part of the rod cover are press-fitted into the upper and lower mounting holes respectively provided in the upper and lower support parts. It is characterized by.

  Furthermore, in addition to the second feature, the present invention forms the upper mounting hole with a larger diameter than the lower mounting hole, while the upper end of each rod cover has a larger diameter than the portion other than the upper end. The third feature is that the large diameter portion is formed.

  According to the first feature of the present invention, most of the suction and exhaust push rods can be arranged outside each bank, so that it is not necessary to form a rod chamber in each bank, and waste is reduced. In addition, each bank can be made more compact and lighter, and since there is no rod chamber, the outer wall of each cylinder cylinder bore can be exposed to a wide range to increase the air cooling effect. be able to.

  In addition, the suction and exhaust push rods arranged outside each bank are housed and protected by rod covers supported by upper and lower support portions projecting from the upper and lower ends of each bank to the valley side, respectively. By arranging the rod cover on the valley side between the first and second banks, not only can the rod cover be protected from contact with other objects by both banks, but also the V-type engine can be made compact. Can be planned.

  Furthermore, the suction and exhaust rocker arms of each bank are arranged in a letter C shape in plan view so that the suction and exhaust push rod side ends are close to each other, so that the suction and exhaust push rods are close to each other. Since the cooling fins of each bank are provided with notches that enable the rod cover that accommodates the suction and exhaust push rods to be placed close to the outer wall of each bank, the width of the notches is minimized and The deterioration of the heat dissipation function of the cooling fin can be minimized.

  According to the second feature of the present invention, each bank is formed by integrally forming a cylinder block and a cylinder head, and the upper support portion is integrated with the cylinder head, and the lower support portion is integrated with the cylinder block. In this way, the upper and lower support holes for press-fitting the upper and lower ends of the rod cover into the upper and lower support parts can be coaxially processed, and the coaxial accuracy of the upper and lower mounting holes can be improved. Press fitting of the rod cover into the lower mounting hole is always appropriate, and the sealing property of the press fitting part can be secured.

  According to the third feature of the present invention, each rod cover can be easily inserted into the upper mounting hole, and the upper end and the lower end of each rod cover can be inserted into the upper and lower mounting holes substantially simultaneously. It can be press-fitted and the press-fitting work becomes easy.

  The form of the Example of this invention is demonstrated below based on the suitable Example of this invention shown to an accompanying drawing.

  1 is a longitudinal front view of an air-cooled general-purpose V-type engine according to the present invention, FIG. 2 is a cross-sectional view taken along line 2-2 of FIG. 1, FIG. 3 is a view taken along arrow 3 in FIG. 4 is a sectional view taken along the line 5-5 in FIG. 4, FIG. 6 is a sectional view taken along the line 6-6 in FIG. 4, FIG. 7 is an explanatory diagram for installing the vaporizer, and FIG. 8 is an explanatory diagram for installing the air cleaner. 9 is an enlarged view of the first bank portion in FIG. 1, FIG. 10 is a sectional view of the first bank alone along the line 10-10 in FIG. 9, FIG. 11 is a view taken along arrow 11 in FIG. 9 is a sectional view taken along arrow 12 in FIG. 9, FIG. 13 is a sectional view taken along line 13-13 in FIG. 12, FIG. 14 is an enlarged view of a portion 14 in FIG.

  First, in FIGS. 1 to 3, the air-cooled general-purpose V-type engine is configured such that a first bank B <b> 1 and a second bank B <b> 2 arranged in a left and right V shape are connected to the upper part of the crankcase 1. An installation flange 2 is formed at the bottom. Further, the starter St is provided on one side of the crankcase 1 so as to be accommodated in the space below the one bank B1.

  The first bank B1 and the second bank B2 each have a cylinder block 3 having a cylinder bore 3a and bolted to the crankcase 1, and a combustion chamber 4a connected to the cylinder bore 3a. The head cover 5 is bolted to the end face of the cylinder head 4. The banks B1 and B2 are integrally formed by casting, and a large number of air cooling fins 6, 6.

  One crankshaft 7 is supported by the front and rear end walls of the crankcase 1, and pistons 8 fitted to the cylinder bores 3a and 3a of the first and second banks B1 and B2 on the crankpin 7p of the crankshaft 7, 8 are connected via connecting rods 9 and 9. The front and rear end walls 1a of the crankcase 1 can be attached to and detached from the main body of the crankcase 1 while supporting one end of the crankshaft 7.

  As shown in FIG. 1, the first and second banks B1 and B2 have an opening angle α between the banks B1 and B2, that is, the cylinder centerline A1 of the first bank B1 and the cylinder centerline 2 of the second bank B2. The formed angle α is 90 °. On the other hand, a counterweight 7w that counterbalances the inertial force of the piston 8 of each bank B1, B2 is attached to the crankshaft 7 opposite to the crankpin 7p.

  Further, in the first and second banks B1 and B2, the cylinder center line A1 of the first bank B1 and the cylinder center line A2 of the second bank B2 are respectively opposite to the banks B1 and B2 from the rotation center A3 of the crankshaft 7. It is arranged so as to pass through the biased point P. According to this arrangement, the valley portion 11 defined between the first and second banks B1 and B2 can be widened while maintaining the opening angle α = 90 ° between the banks B1 and B2. The valley portion 11 accommodates the entire carburetor C, which is an auxiliary machine for the V-type engine E, and a part of the air cleaner Ac in which the cleaner element 10 is built.

  As clearly shown in FIG. 6, the carburetor C has a first and second horizontal direction (a direction orthogonal to the crankshaft 7) aligned with the carburetor body 12 in the arrangement direction of the first and second banks B <b> 1 and B <b> 2. The air intake passages 131 and 132 are formed to be close to each other. The float chamber 12a and the fuel cut solenoid valve 12b are attached to the lower part of the carburetor body 12.

  As shown in FIGS. 1, 4 and 5, the cylinder heads 4 and 4 of the first and second banks B1 and B2 have an intake port 14 opened to each combustion chamber 4a in addition to each combustion chamber 4a. An exhaust port 15 is formed. Open ends of the intake port 14 and the exhaust port 15 to the combustion chamber 4 a are formed in the intake valve seat 80 and the exhaust valve seat 81. At that time, the intake valve seat 80 is formed to have a larger diameter than the exhaust valve seat 81. The intake valve seat 80, the exhaust valve seat 81, and the plug mounting hole 87 into which the spark plug 23 is screwed are disposed so as to surround the center of the combustion chamber 4a.

  As shown in FIGS. 9 to 11, the cylinder heads 4 of the banks B <b> 1 and B <b> 2 have intake valves that open and close the intake port 14 and the exhaust port 15 in cooperation with the intake valve seat 80 and the exhaust valve seat 81, respectively. 35a, 35b and exhaust valves 36a, 36b are attached, and a spark plug 23 for screwing an electrode to the combustion chamber 4a is screwed. At this time, the intake valves 35a and 35b and the exhaust valves 36a and 36b are arranged in a V shape, and the intake and exhaust valves 35 and 36 are provided with valve springs 61 and 62 for urging them in the valve closing direction. Is installed.

  The inclination angles θ1 and θ2 of the axes of the intake valves 35a and 35b and the exhaust valves 36a and 36b arranged in a V shape with respect to the center line of the cylinder bore 3a are as shown in FIG. The seat 81 is set as large as possible within a range that can be cut by the rotary blades 82 and 83 inserted into the cylinder bore 3a.

  As shown in FIGS. 1, 4, 5 and 6, the first and second intake passages 131, 132 are connected to the intake ports 14, 14 of the first and second banks B 1, B 2 via the intake manifold 16. Connected.

  In other words, the intake manifold 16 is U-shaped on the outer side of the valley portion 11 on the horizontal plane so as to communicate between the intake ports 14 and 14 of the first and second banks B1 and B2 and the first and second intake passages 131 and 132, respectively. The first and second pipes 17 and 18 are curved in a shape, and individual flanges 191 and 192 are formed at the downstream ends of the first and second pipes 17 and 18, respectively. Are connected to the cylinder heads 4 and 4 of the first and second cylinder heads 4 and 4 by bolts 24 and 24, respectively. The common flange 20 includes a heat insulating plate 21, first and second mounting flanges 28 and 29 formed at the downstream end and the upstream end of the vaporizer C, and the outer periphery of the elbow-shaped air outlet pipe 22 of the air cleaner Ac. The mounting flange 30 formed in the step is fastened together by a plurality of bolts.

  Next, the joint fastening structure will be described with reference to FIGS.

  Two stud bolts 25 and 25 and two holding bolts 26 and 26 are used in the above-described tightening structure. The two stud bolts 25, 25 are planted in two places above and below one side of the common flange 20 of the intake manifold 16, and two holding bolts 26, 26 are screwed on the other side of the common flange 20. A pair of upper and lower screw holes 27, 27 to be worn are provided. In addition, the first bolt holes 31, 31, 31 ′ through which the two implanted bolts 25, 25 pass are formed in the heat insulating plate 21, the first and second mounting flanges 28, 29 of the vaporizer C and the mounting flange 30 of the air cleaner Ac. 31 'and second bolt holes 32, 32 through which the two holding bolts 26, 26 pass. In particular, the first bolt holes 31', 31 'of the first mounting flange 28 of the vaporizer C are The flange 28 is formed in a notch shape opened to the outside.

  In addition, a gasket is interposed before and after the heat insulating plate 21 as necessary.

  1 to 3, 9, 14, and 15, the valve operating device 37 that opens and closes the intake valves 35 a and 35 b and the exhaust valves 36 a and 36 b of the first and second banks B <b> 1 and B <b> 2 includes the crankcase 1. To the cylinder heads 4 of the banks B1 and B2. The valve operating device 37 includes a camshaft 38 supported by the front and rear end walls of the crankcase 1 directly above and parallel to the crankshaft 7, and the rotation of the crankshaft 7 is reduced by half to the camshaft 38. And a timing transmission device 39 (see FIG. 2) for transmission. The timing transmission device 39 meshes with the driving timing gear 40 fixed to the crankshaft 7 at a position adjacent to the inner surface of the detachable end wall 1a of the crankcase 1 and the driving timing gear 40 fixed to the camshaft 38. And a driven timing gear 41.

  As shown in FIGS. 14 and 15, the camshaft 38 is integrally formed with an intake cam 38i and an exhaust cam 38e. The intake cam 38i includes first and second intake cam followers 42a, 42b, first and second The second intake push rods 44a and 44b are connected to the intake valves 35a and 35b of the first and second banks B1 and B2 via the first and second intake rocker arms 71a and 71b (see FIGS. 1 and 3). The exhaust cam 38e is connected to the first and second banks B1, B2 via the first and second exhaust cam followers 43a, 43b, the first and second exhaust push rods 45a, 45b, and the first and second exhaust rocker arms 72a, 72b. Are connected to the exhaust valves 36a and 36b. The intake push rods 44a and 44b and the exhaust push rods 45a and 45b are arranged along the side surfaces of the corresponding banks B1 and B2 on the valley portion 11 side.

  As clearly shown in FIGS. 14 and 15, the first and second intake cam followers 42 a and 42 b and the first and second exhaust cam followers 43 a and 43 b are attached to the crankcase 1 immediately above and parallel to the cam shaft 38. A boss 47 that is swingably supported by the cam follower shaft 46 and a slipper 48 that slides on the corresponding cams 38i and 38e are provided. In the first and second intake cam followers 42a and 42b, The boss portions 47 and 47 are brought into contact with and adjacent to each other on the cam follower shaft 46, and the slipper portions 48 and 48 are arranged in the axial direction of the cam shaft 38 so that the slipper portions 48 and 48 are opposed to each other with the intake cam 38i interposed therebetween. Are extended alternately, and the first and second exhaust cam followers 43a and 43b also have boss portions 47 and 47. On the cam follower shaft 46, they are brought into contact with each other and adjacent to each other, and the ends of the slipper portions 48, 48 along the axial direction of the cam shaft 38 are staggered so that the exhaust cams 38e are opposed to each other. It is extended to.

  One end of the cam follower shaft 46 is supported by the support hole 50 of the crankcase 1, and the other end is supported by a bracket 51 fixed to the crankcase 1 with a bolt 52. The cam follower shaft 46 includes a distance collar 53 that contacts the outer end surface of one boss portion 47 of the first and second exhaust cam followers 43a and 43b, first and second intake cam followers 42a and 42b, and first and second A coil spring 54 interposed between the boss portions 47, 47 of the exhaust cam followers 43a, 43b is provided, whereby the first and second suction and exhaust cam followers 42a, 43a; 42b, 43b are arranged at a predetermined intermediate position of the cam follower shaft 46. Is held adjacent to the part. And most of the suction and exhaust cams 38i and 38e, and the first and second suction and exhaust cam followers 42a and 43a; 42b and 43b are formed between the extended surfaces F and F on both end surfaces of the crankpin 7p of the crankshaft 7. It is arranged to fit in.

  As shown in FIG. 15, hemispherical engagement recesses 55, 55... Are formed on the back surfaces of the first and second intake cam followers 42a, 42b and the first and second exhaust cam followers 43a, 43b. The engaging spherical recesses 55, 55 of the second intake cam followers 42a, 42b are engaged with the semispherical lower ends of the first and second intake push locks 44a, 44b, and the first and second exhaust cam followers 43a, 43b The engaging concave portions 55, 55 engage with the hemispherical lower ends of the first and second exhaust push rods 45a, 45b.

  As shown in FIG. 3, in the first and second banks B1 and B2, the first and second intake rocker arms 71a and 71b and the first and second exhaust rocker arms 72a and 72a are respectively connected to the corresponding cylinder heads 4 by rocker shafts. It is pivotally supported via 85 and 86. Each suction / exhaust rocker arm 71a, 72a; 71b, 72b is arranged in a C shape in plan view so that the suction and exhaust push rods 44a, 45a; 44b, 45b side ends are close to each other. The suction and exhaust push rods 44a, 45a; 44b, 45b are arranged close to each other.

  Tubular rod covers 59 and 60 (see FIGS. 1, 9, 11 and 12) for accommodating the suction and exhaust push rods 44a and 45a; 44b and 45b arranged adjacent to each other are next to the banks B1 and B2. It is attached like this.

  That is, each bank B1, B2 is integrally formed with upper and lower support portions 74, 75 projecting from the upper and lower ends thereof to the valley 11 side between the banks B1, B2, respectively. Are provided with upper mounting holes 74h and 74h into which the upper ends of the rod covers 59 and 60 are press-fitted, and the lower support part 75 is provided with lower mounting holes 75h and 75h into which the lower ends of the rod covers 59 and 60 are press-fitted. . Each upper mounting hole 74h and lower mounting hole 75h are coaxially arranged, and the upper mounting hole 74h is formed to have a larger diameter than the lower mounting hole 75h. Correspondingly, the upper ends 59a, 60a of the rod covers 59, 60 are formed with a larger diameter than the other parts. Therefore, the rod covers 59 and 60 can be easily inserted into the upper mounting holes 74h and 74h from above, and can be press-fitted into the upper mounting holes 74h and 74h and the lower mounting holes 75h and 75h almost simultaneously. .

  In each of the banks B1 and B2, the valve springs 61 and 62, the intake rocker arms 71a and 71b, and the exhaust rocker arms 72a and 72b are accommodated in a valve operating chamber 63 defined between the cylinder heads 4 and the head cover 5. The chamber 63 communicates with the inside of the crankcase 1 through the hollow portions of the rod covers 59 and 60.

  On the other hand, as shown in FIGS. 9 and 12, the cooling fins 6 of the banks B1 and B2 have U-shaped cuts that enable the rod covers 59 and 60 to be disposed close to the outer walls of the banks B1 and B2. A notch 6a is provided.

  In FIG. 2 again, a flat portion 64 is formed on the cam shaft 38 from the general surface of the cam shaft 38 to the base surface of the exhaust cam 38 e, and the decompression member 66 can swing on the flat portion 64 via the pivot 65. Supported. The decompression member 66 is made of a steel plate. When the V-type engine E is stopped or started, the decompression member 66 is located on the base surface side of the exhaust cam 38e and protrudes from the base surface. When the rotation is more than idling, the decompression arm 66a is provided with a centrifugal weight 66b that generates a centrifugal force to retract the decompression arm 66a from the base surface. The decompression arm 66a is positioned on the base surface side of the decompression member 66. The return spring 69 that is biased in the direction to be moved is connected, and the decompression device 70 is configured as described above.

  Thus, when the V-type engine E is started, the decompression arm 66a occupies a position where the tip of the decompression arm 66a protrudes from the base surface of the exhaust cam 38e (see the chain line in FIG. 15). By slightly opening the exhaust valves 36a and 36b of the first and second banks B1 and B2 by the minute lift of the first and second exhaust cam followers 43a and 43b, the compression pressure in the cylinder bores 3a and 3a is lowered, and the starting load is reduced. be able to. After the start of the V-type engine E, if the camshaft 38 rotates at a predetermined rotational speed or more, the centrifugal weight 66b swings radially outward against the set load of the return spring 69 by the centrifugal force acting on it. The decompression arm 66a is moved away from the base surface of the exhaust cam 38e.

  In the above, the suction and exhaust push rods 44a, 45a; 44b, 45b are all provided with compatibility, and the same push rod can be used. Also, the intake and exhaust cam followers 42a, 43a; 42b, 43b are all provided with compatibility, and the same cam follower can be used. Furthermore, compatibility is given to the rod covers 59 and 60, and the same rod cover can be used. In this way, the mass productivity of parts can be increased.

  Next, the operation of this embodiment will be described.

  As described above, the first and second banks B1 and B2 are arranged such that the opening angle α of both banks B1 and B2 is 90 °, while the crankshaft 7 has pistons in the banks B1 and B2. Since the counterweight 7w that balances the inertial force of 8 is attached opposite to the crankpin 7p, the inertial force at the top dead center and the bottom dead center of each of the banks B1 and B2 is, as is well known, the counterweight. Therefore, the primary inertial force of the V-type engine E can be balanced without providing a special primary balancer mechanism.

  Moreover, the first and second banks B1 and B2 are such that the cylinder center line A1 of the first bank B1 and the cylinder center line A2 of the second bank B2 are opposite to the banks B1 and B2 from the rotation center A3 of the crankshaft 7, respectively. The valley portion 11 defined between the first and second banks B1 and B2 is maintained at an opening angle α = 90 ° between the banks B1 and B2. Can be widened with a spear, and therefore. The valley portion 11 can accommodate the entire carburetor C, which is an auxiliary machine of the V-type engine E, and a part of the air cleaner Ac with a margin, and can provide a compact V-type engine E with a low overall height. it can.

  Further, at that time, the carburetor C has two series of first and second intake passages 131 and 132 in a horizontal direction (a direction orthogonal to the crankshaft 7) arranged in the arrangement direction of the first and second banks B1 and B2. Since it is configured as a mold and individually connected to the intake ports 14 and 14 of the first and second banks B1 and B2 through a pair of pipes 17 and 18, intake interference between both banks B1 and B2 is avoided. In addition, the output resistance of the V-type engine E can be improved by minimizing the intake resistance.

  Moreover, the pair of pipes 17 and 18 are formed in the intake manifold 16 by forming a common flange 20 integrally connecting them at their upstream end portions, so that the common flange 20 is double-vaporized. By connecting to the downstream end of the container C, the intake system of the V-type engine E can be easily configured, and the assemblability of the intake system is improved.

  When attaching the heat insulating plate 21, the carburetor C and the air cleaner Ac to the common flange 20 of the intake manifold 16, first, as shown in FIG. The first bolt holes 31, 31 of the heat insulating plate 21 are fitted into 25, 25, and then the notched first bolt holes 31 ′, 31 ′ of the first mounting flange 28 of the vaporizer C are inserted into the studs 25, 25. After engaging from the side (see FIG. 7 (A)), the entire vaporizer C is moved to the heat insulating plate 21 side, and the first bolt holes 31, 31 of the second mounting flange 29 are inserted into the stud bolts 25, 25 (see FIG. 8). By doing so, the carburetor C having a relatively long axial length can be set at a predetermined fitting position with the implantation bolts 25 and 25 with a movement amount shorter than the axial length of the carburetor C. Even when there is no wide space for receiving the entire carburetor C outside the outer ends of the implantation bolts 25, 25, the setting operation can be performed quickly, and the temporary fixation of the carburetor C to the fixed position is possible. It becomes possible. In the case of this embodiment, as shown in FIG. 4, the bulging portion 1s of the crankcase 1 is present outside the outer ends of the studs 25, 25 due to the presence of the large-diameter driven timing gear 41. The bulging portion 1s prevents the float chamber 12a of the carburetor C and the solenoid valve 12b for fuel cut from receiving the implanted bolts 25 and 25 outside the outer ends, so that the bulging portion 1s is not interfered with. The temporary fixing structure of the vaporizer C at a fixed position is extremely effective.

  Next, as shown in FIG. 8, the first bolt holes 31, 31 of the mounting flange 30 of the air cleaner Ac are fitted into the stud bolts 25, 25, and finally nuts 33, 33 are screwed onto the outer ends of the stud bolts 25, 25. On the other hand, the holding bolts 26 and 26 are inserted into all the second bolt holes 32 and 32 and screwed and tightened into the screw holes 27 and 27 of the common flange 20. When the presser bolt 26 is inserted into the second bolt hole 32, it is necessary to move the presser bolt 26 over the entire length of the vaporizer C. However, since the presser bolt 26 is thin, its movement space is generally easily secured. it can.

  In the above, the use of the two implantation bolts 25, 25 means that the two first bolt holes 31, 31 of the heat insulating plate 21, the vaporizer C, and the air cleaner Ac are fitted into these implantation bolts 25, 25. Thus, a reliable temporary fixing state in which rotation around the implanted bolts 25, 25 of the heat insulating plate 21, the vaporizer C, and the air cleaner Ac is prevented is obtained. Therefore, the second bolt holes of the subsequent holding bolts 26, 26 are obtained. The insertion operation to 32 and 32 and the screwing operation to the screw holes 27 and 27 become easy.

  Further, by using the holding bolts 26 and 26 together, the carburetor C can be accurately fixed in place without being affected by the presence of the notched first bolt holes 31 ′ and 31 ′. Since the first and second attachment flanges 28 and 29 formed at the downstream and upstream ends of the vaporizer C are fastened to the common flange 20 by the stud bolts 25 and 25 and the holding bolts 26 and 26, the attachment strength of the vaporizer C Can be increased.

  When removing the carburetor C and the air cleaner Ac from the common flange 20, the above work procedure may be reversed.

  In the valve train 37, the suction and exhaust rocker arms 71a, 72a; 71b, 75b of the banks B1, B2 are arranged so that their suction and exhaust push rods 44a, 45a; 44b, 45b side ends are close to each other. Each pair of suction and exhaust push rods 44a, 45a; 44b, 45b are arranged close to each other in plan view, and each pair of suction and exhaust push rods 44a, 45a; 44b, 45b is accommodated. The upper and lower ends of the tubular rod covers 59, 60 are supported by upper and lower support portions 74, 75 projecting from the upper and lower ends of the banks B1, B2 to the valley 11 side, respectively, and the banks B1, B2 are supported. Since the cooling fin 6 of B2 is provided with a notch 6a that enables the rod covers 59 and 60 to be disposed close to the outer walls of the banks B1 and B2, each suction and exhaust block is provided. Most of the shrods 44a, 45a; 44b, 45b can be arranged outside the banks B1, B2, and it is not necessary to form a rod chamber in each bank B1, B2, and the waste is reduced. The banks B1 and B2 can be made compact and thus light, and the outer wall of the cylinder bore 3a of each of the banks B1 and B2 can be exposed to a wide range because it does not have a rod chamber. The air cooling effect can be enhanced.

  The suction and exhaust push rods 44a, 45a; 44b, 45b arranged outside the banks B1, B2 are upper and lower support portions that project from the upper and lower ends of the banks B1, B2 to the valley 11 side, respectively. The rod covers 59, 60 are accommodated and protected by rod covers 59, 60 supported by 74, 75, and the rod covers 59, 60 are arranged on the side of the valley 11 between the first and second banks B1, B2. The rod covers 59 and 60 are protected from contact with other objects by the banks B1 and B2.

  Further, each suction and exhaust rocker arm 71a, 72a; 71b, 75b of each bank B1, B2 is formed in a letter C in plan view so that the suction and exhaust push rods 44a, 45a; 44b, 45b side ends are close to each other. The suction and exhaust push rods 44a, 45a; 44b, 45b are arranged close to each other, and the suction and exhaust push rods 44a, 45a; 44b, 45b are placed on the cooling fins 6 of the banks B1, B2. Since the notches 6a that allow the rod covers 59 and 60 to be accommodated to be close to the outer walls of the banks B1 and B2 are provided, the width of the notches 6a is minimized, and the heat dissipation function of the cooling fins 6 by the notches is provided. Degradation can be minimized.

  Each cam follower 42a, 43a, 42b, 43b is connected to a cam follower shaft 46 mounted on the crankcase 1 directly above and parallel to the cam shaft 38, and a corresponding cam 38i. In the first and second intake cam followers 42a and 42b, the boss portions 47 and 47 are brought into contact with each other on the cam follower shaft 46, and the slipper portion 48, One end of the slippers 48, 48 along the axial direction of the cam shaft 38 is alternately extended so that the 48 is opposed to the intake cam 38i, and the first and second exhaust cam followers 43a, 43b are also provided. The boss portions 47 and 47 are brought into contact with and adjacent to each other on the cam follower shaft 46, and the slipper portions 48 and 48 are connected to the exhaust cover. Since the end portions of the slipper portions 48, 48 along the axial direction of the cam shaft 38 are alternately extended so as to face each other across the 38e, the first cam shaft 38 and the cam follower shaft 46 have a first end. The suction / exhaust cam followers 42a, 43a and the second suction / exhaust cam followers 42b, 43b can be arranged in a centralized manner, whereby the valve operating device 37 can be made compact, in particular, the cam shaft 38 can be shortened. In addition, in each of the first and second intake cam followers 42a, 42b and the first and second exhaust cam followers 43a, 43b, the slippers 48, 48; 48, 48 facing each other with the cams 38i, 38e interposed therebetween are opposed to each other. By alternately extending one end portion of the slipper along the axial direction of the cam shaft 38, it is possible to sufficiently secure a sliding contact area with the corresponding cams 38i, 38e of the slippers 48, 48; Therefore, it is possible to sufficiently reduce the surface pressure of the sliding contact portion and contribute to the improvement of the wear resistance.

  Further, the first and second suction and exhaust cam followers 42a and 43a; 42b and 43b of the banks B1 and B2 and most of the suction and exhaust cams 38i and 38e are extended surfaces F of both end surfaces of the crankpin 7p of the crankshaft 7. , F can be further reduced in size, and the valve operating device 37 can be made more compact, and the crankshaft 7 can be sucked by the lubricating oil scattered from around the crankpin 7p during the rotation of the crankshaft 7 and the exhaust cams 38i, 38e can be surrounded. It can be effectively lubricated.

  Further, a flat portion 64 is formed on the cam shaft 38 from its general surface to the base surface of the exhaust cam 38e, and a decompression member 66 is pivotally supported on the flat portion 64, and this decompression member 66 is connected to the V-type engine. When E is stopped or started, the tip of the exhaust cam 38e is at the operating position on the base surface side so that the first and second exhaust cam followers 43a and 43b are lifted during the compression stroke of the V-type engine E. A decompression arm 66a that protrudes and a centrifugal weight 66b that generates centrifugal force to cause the decompression arm 66a to retreat from the base surface when the V-type engine E rotates more than idling, and the decompression member 66 includes Since the return spring 69 for biasing the arm 66a toward the operating position is connected, the first and second exhaust cam followers 43 are connected. 43b, the bosses are abutted on and adjacent to each other on the cam follower shaft, and the ends of the slippers along the axial direction of the cam shaft 38 are staggered so that the slippers face each other across the exhaust cam. In combination with the extension of the decompression member 66, the distal end portion of the decompression arm 66a is slightly protruded toward the exhaust cam 38e, and the distal end portion of the decompression arm 66a is projected to the first and second exhaust cam followers 43a. , 43b, and a minute lift can be imparted to them. At this time, the fact that the protruding length of the distal end portion of the decompression arm 66a toward the exhaust cam 38e is small is sufficient to reduce the size of the single decompression device 70 common to both the banks B1 and B2, and the exhaust cam. This means that it is possible to minimize the reduction in the effective area of the base surface of 38e due to the formation of the flat portion 64 and to improve the durability of the exhaust cam 38e and the exhaust cam followers 43a and 43b. To do.

  The flat portion 64 is formed from the general surface of the camshaft 38 to the base surface of the exhaust cam, and the decompression arm 66a of the decompression member 66 pivotally supported on the flat portion 64 is used when the V-type engine E is stopped or started. Since the exhaust cam 38e protrudes toward the base surface side, the slipper portions 38 and 38 of the first and second exhaust cam followers 43a and 43b do not need to protrude outward from the exhaust cam 38e. Decompression at start-up can be performed while maintaining compactness.

  As mentioned above, although the Example of this invention was explained in full detail, this invention can perform a various design change in the range which does not deviate from the summary.

1 is a longitudinal front view of an air-cooled general-purpose V-type engine according to the present invention. FIG. 2 is a sectional view taken along line 2-2 in FIG. 1. FIG. 3 is a view taken in the direction of arrow 3 in FIG. 1. FIG. 4 is a sectional view taken along line 4-4 of FIG. FIG. 5 is a sectional view taken along line 5-5 of FIG. FIG. 6 is a sectional view taken along line 6-6 in FIG. FIG. 4 is a sectional view taken along line 4-4 of FIG. Explanatory drawing of how to install the vaporizer. The enlarged view of the 1st bank part in FIG. FIG. 10 is a cross-sectional view of a first bank along the line 10-10 in FIG. 9; FIG. 11 is a view taken in the direction of arrow 11 in FIG. 19. FIG. 12 is a view taken in the direction of arrow 12 in FIG. 9. FIG. 13 is a sectional view taken along line 13-13 of FIG. FIG. 14 is an enlarged view of a portion 14 in FIG. 2. FIG. 15 is a sectional view taken along line 15-15 in FIG. 14;

Explanation of symbols

B1 ··· First bank B2 ··· Second bank E · · · V-type engine 1 · · · Crankcase 3 · · · Cylinder block 3a · · · Cylinder bore 4 ··· ... Cylinder head 7 ... Crankshaft 11 ... Valleys 35a, 35b ... Intake valves 36a, 36b ... Exhaust valves 38 ... Camshafts 42a, 42b ... 1, 2nd intake cam followers 43a, 43b ... 1st, 2nd exhaust cam followers 44a, 44b ... 1st, 2nd intake push rods 45a, 45b ... 1st, 2nd exhaust push rods 59, 60 ... Rod covers 71a, 71b ... Intake rocker arms 72a, 72b ... Exhaust rocker arms 74 ... Upper support part 75a ... Upper attachment hole 75 ... Lower support part 75a ... Lower attachment Hole

Claims (3)

Each has a cylinder bore (3a) and supports the crankshaft (7) with the first and second banks (B1, B2) arranged in a V shape so as to define a trough (11) between them. In addition to being connected to the crankcase (1), cooling fins (6) are projected from the outer walls of the banks (B1, B2), and suction and exhaust valves (35a, 36a) are placed on the heads of the banks (B1, B2). 35b, 36b) are arranged in a V shape, and a valve operating device (37) for opening and closing the intake and exhaust valves (35a, 36a; 35b, 36b) is disposed above the crankshaft (7). A camshaft (38) driven from the crankshaft (7), a first suction / exhaust cam follower (42a, 43a) and a first suction / exhaust cam follower (42a, 43a) respectively lifted and lowered by the suction and exhaust cams (38i, 38e) A second suction and exhaust cam follower (42b, 43b); The first suction and exhaust cam followers (42a and 43a) and the second suction and exhaust cam followers (42b and 43b) are connected to the lower ends of the first and second banks (B1 and B2), respectively. First suction, exhaust push rods (44a, 45a) and second suction, exhaust push rods (44b, 45b), these first suction, exhaust push rods (44a, 45a) and second First suction and exhaust rocker arms (71a, 72a) respectively connected to the suction and exhaust valves (35a, 36a; 35b, 36b) of the corresponding banks (B1, B2) at the upper ends of the suction and exhaust push rods (44b, 45b) And an air-cooled V-type engine constituted by the second suction and exhaust rocker arms (71b, 72b),
The suction and exhaust rocker arms (71a, 72a; 71b, 72b) of the banks (B1, B2) are arranged so that their suction and exhaust push rod (44a, 45a; 44b, 45b) side ends are close to each other. Arranged in a C shape in plan view, the suction and exhaust push rods (44a, 45a; 44b, 45b) are brought close to each other, and the suction and exhaust push rods (44a, 45a; 44b, 45b) are accommodated respectively. The upper and lower support portions (74, 74) projecting from the upper and lower ends of the banks (B1, B2) to the valley (11) side, respectively. 75), and the cooling fins (6) of the banks (B1, B2) are notched to allow the rod cover (59, 60) to be placed close to the outer wall of the banks (B1, B2) ( Air-cooled V-type engine, characterized in that a a). The air-cooled V-type engine according to claim 1,
Each bank (B1, B2) is formed by integrally molding a cylinder block (3) having a cylinder bore (3a) and a cylinder head (4) for supporting intake and exhaust valves (35a, 36a; 35b, 36b). In addition, the upper support portion (74) is integrally formed on the cylinder head (4), and the lower support portion (75) is integrally formed on the cylinder block (3), and these upper and lower support portions (74h, 75h) are integrally formed. The air-cooled V-type engine is characterized in that the upper and lower ends of the rod cover (59, 60) are press-fitted into the upper and lower mounting holes (74h, 75h) respectively provided in the upper and lower mounting holes. The air-cooled V-type engine according to claim 2,
The upper mounting hole (74h) is formed to have a larger diameter than the lower mounting hole (75h), while the upper end portion of the rod cover (59, 60) is a large diameter portion having a larger diameter than the portion other than the upper end portion. An air-cooled V-type engine characterized by being formed in (59a, 60a).

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