JP2014066168A - Reciprocating internal combustion engine, crankshaft, vehicle and motorcycle - Google Patents

Abstract

An engine capable of efficiently generating an unbalanced moment and suppressing the overall weight is provided.
A crankshaft 60 includes a plurality of crank pins 641 to 644 and has a rotational couple. The crankcase 810 rotatably supports a plurality of journals 621 to 625 of the crankshaft 60. The crankcase 810 has a thrust receiving portion 680 that restricts movement of the crankshaft 60 in the thrust direction. Of a plurality of counterweights 631 to 638 that are spaced apart from each other in the axial direction of the crankshaft 60, a gear 639 that outputs engine rotational power is provided on the outer periphery of the counterweight 637 that is disposed on one end side of the crankshaft 60. It is formed. The thrust receiving portion 680 is provided on the side surface of the journal receiving inner wall 812 disposed on the other end side of the crankshaft 60.
[Selection] Figure 3

Description

  The present invention relates to a reciprocating internal combustion engine, a vehicle, and a two-wheeled vehicle, and particularly to a reciprocating internal combustion engine, a crankshaft, a vehicle, and a two-wheeled vehicle that include a cross-plane crankshaft as a crankshaft.

  2. Description of the Related Art Conventionally, a crankshaft (crankshaft) in a multi-cylinder reciprocating internal combustion engine is rotatably supported by a bearing portion of a crankcase with a plurality of journals serving as rotating shaft portions. As a crankshaft, for example, as shown in Patent Document 1, a reduction gear is provided on the outer periphery of a counterweight disposed on one end side, and this reduction gear is meshed with a reduction gear on the clutch side of the transmission. Thus, a configuration for transmitting power is known.

  In the crankcase that rotatably supports the crankshaft, the thrust receiving portion is provided in the bearing portion that receives the journal coupled to the counterweight with a reduction gear. By receiving the side surface of the counterweight with a reduction gear to which the journal is coupled and the side surface of the counterweight on both side surfaces of the thrust receiving portion, movement of the crankshaft in the thrust direction is restricted. In the counterweight, the surface facing the thrust receiving portion is finished to be a smooth surface polished with high accuracy because of its sliding characteristics. The other bearing portions are provided such that when the journal is supported, a predetermined interval is provided between each of the counterweight connected by the journal and the web. Thereby, even when the counterweight and the web expand and contract with the expansion and contraction of the crankshaft due to the temperature change of the reciprocating internal combustion engine, it is acceptable.

JP 63-61733 A

  In the reciprocating internal combustion engine configured as described in Patent Document 1 described above, there is a desire to use a cross-plane crankshaft in which a plurality of crankpins are arranged at a phase of 90 degrees.

  In the reciprocating internal combustion engine having this configuration, as shown in Patent Document 1, the crankshaft is directly processed into a counterweight on one end side to form a reduction gear. In this case, the outer periphery of the counterweight on which the gear is formed needs to be an outer periphery having no missing portion.

  For this reason, for counterweights with reduced gears, the balance to counteract the unbalanced force (unbalance) of the rotational balance in the crankshaft caused by the inertial force generated by the reciprocating motion of the piston and connecting rod. The weight is difficult to set.

  Therefore, in a crankshaft equipped with a counterweight with a reduction gear at one end, a counterweight in the vicinity of the counterweight with a reduction gear (a counterweight connected to the counterweight with a reduction gear by a journal or a crankpin) Set.

  On the other hand, in the case of the cross-plane type, couples are also generated due to the imbalance of the inertial force in each cylinder, but when setting the counterweight for canceling the couples to the counterweight of the crankshaft, it is necessary to generate couples The counterweight is more effective as it is set closer to both ends of the crankshaft length. This is because in the cross plane, the closer to both ends, the greater the couple generated per weight, and the smaller the weight required to obtain the required couple.

  Therefore, in a cross-plane type crankshaft in which a counterweight with a reduction gear is arranged on one end side, it is desirable to set a counterweight with a counterweight other than the counterweight with a reduction gear on both ends including the one end side. It is.

  Further, in the reciprocating internal combustion engine disclosed in Patent Document 1, the thrust receiving portion is disposed adjacent to the counterweight with a reduction gear.

  Further, the counterweight or web received by the thrust receiving portion needs to have a smooth surface that comes into contact with the thrust receiving portion in the rotation axis direction. This smooth surface is finished by high-precision polishing because of the sliding characteristics on the contact surface.

  On the other hand, a counterweight or web that does not have a thrust receiving portion does not require a smooth surface that contacts the thrust receiving portion. Therefore, the thickness of the counterweight or web that does not have the thrust receiving portion can be increased as long as it does not come into contact with the bearing portion of the crankcase.

  Therefore, when a cross-plane crankshaft is used in, for example, an engine with a uniform bore pitch, it is necessary to reduce the thickness of the counterweight received by the thrust receiver compared to the thickness of the counterweight not received by the thrust receiver. Arise.

  Thus, in a cross-plane type crankshaft, when the counterweight with gear on one end is received and supported by the thrust receiving portion, the counterweight received by the thrust receiving portion is a shape for setting a counterweight ( The degree of freedom in (thickness) is limited.

  Therefore, in the cross-plane type crankshaft, it is necessary to set a larger unbalanced moment with a counterweight other than the counterweight that receives the thrust receiving portion at one end side, which is difficult to set.

  That is, in a cross-plane crankshaft, if a thrust receiver is provided on the same side as the geared counterweight with respect to the center in the longitudinal direction, an unbalance force is exerted on the end side where the unbalance moment per weight is large. It will be difficult to set. As a result, it is difficult to set an unbalanced moment, and there is a problem that the weight increases when a necessary couple is obtained.

  The present invention has been made in view of such points, and provides a reciprocating internal combustion engine, a crankshaft, a vehicle, and a motorcycle that can efficiently generate an unbalanced moment and can suppress the overall weight. Objective.

  One aspect of the reciprocating internal combustion engine of the present invention includes a crankshaft having a plurality of crankpins and having a rotational couple, and a crankcase that rotatably supports a plurality of journals of the crankshaft. A multi-cylinder reciprocating internal combustion engine, wherein the crankcase has a thrust receiving portion that restricts movement of the crankshaft in the thrust direction, and a plurality of counters that are spaced apart in the axial direction of the crankshaft Of the weights, a gear for outputting the rotational power of the engine is formed on the outer periphery of the counterweight disposed on one end side of the crankshaft, and the thrust receiving portion is the other of the plurality of journals in the crankshaft. A structure that supports a journal disposed on an end side and is provided in a journal receiving portion provided in the crankcase. That.

  One aspect of the crankshaft according to the present invention is a crankshaft used for a reciprocating internal combustion engine having a plurality of crankpins and having a rotational couple, and spaced apart in the axial direction. A plurality of counterweights, and the crankpins and a plurality of journals pivotally supported by the crankcase are alternately arranged between the counterweights, and one end of the plurality of counterweights in the axial direction. A gear for outputting the rotational power of the engine is provided on the outer periphery of the counterweight arranged on the side of the counter, and a pair of thrust is formed on the side of the counterweight connected to the journal in the counterweight arranged on the other end A configuration in which a receiving surface is provided is adopted.

  One aspect of the vehicle of the present invention employs a configuration including the reciprocating internal combustion engine configured as described above. One aspect of the motorcycle of the present invention employs a configuration including the reciprocating internal combustion engine configured as described above.

  According to the present invention, an unbalanced moment can be generated efficiently and the overall weight can be suppressed.

1 is a left side view of a motorcycle including a reciprocating internal combustion engine according to Embodiment 1 of the present invention. FIG. 1 is a left side view schematically showing the positional relationship between the shafts in the engine shown in FIG. Axial cross-sectional view of the engine corresponding to the cross section indicated by line AA in FIG. FIG. 2 is a cross-sectional view of the engine corresponding to the cross section indicated by line BB in FIG. The figure which shows the arrangement of the crank pin in the crankshaft schematically 6A is a cross-sectional view showing a positional relationship between a journal receiving inner wall and a CW. FIG. 6A is a cross-sectional view of a journal receiving inner wall having a thrust receiving portion and a CW having a thrust surface, and FIG. 6B is a journal receiving inner wall without a thrust receiving portion. Sectional view of CW with no thrust surface 6A and 6B are cross-sectional views in which each journal receiving inner wall and CW are overlapped. The left view of an engine provided with the reciprocating internal combustion engine which concerns on Embodiment 2 of this invention FIG. 8 is an axial sectional view of the engine corresponding to the portion indicated by line CC in FIG. FIG. 8 is a cross-sectional view of the engine corresponding to the cross section indicated by the line DD in FIG. The schematic diagram which shows the modification of Embodiment 2 of this invention The schematic diagram which shows the modification of the crankshaft which concerns on each embodiment of this invention The schematic diagram which shows the modification of the crankshaft which concerns on each embodiment of this invention The schematic diagram which shows the modification of the crankshaft which concerns on each embodiment of this invention

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

(Embodiment 1)
FIG. 1 is a left side view of a motorcycle including a reciprocating internal combustion engine according to Embodiment 1 of the present invention. In the present embodiment, a vehicle including a reciprocating engine that is a reciprocating internal combustion engine will be described as a motorcycle. In the present embodiment, front, rear, left, and right mean front, rear, left, and right when viewed in the state of being seated on the seat of the motorcycle.

  The engine which is the reciprocating internal combustion engine of the present embodiment is provided integrally with the transmission. In addition, although the vehicle in which the engine which concerns on this Embodiment is mounted was made into the motorcycle, it is not restricted to this. The vehicle on which the engine according to the present embodiment is mounted may be a saddle-ride type vehicle on which a driver rides, for example, a three-wheel or a four-wheel saddle-ride type vehicle. First, an outline of a motorcycle equipped with an engine unit including the transmission according to the present embodiment will be described.

(1) Configuration of Motorcycle As shown in FIG. 1, in the motorcycle 10, a head pipe 2 is provided on the front end side of the main frame 1. The main frame 1 is formed to be inclined downward while extending rearward, and an engine 8 including a reciprocating engine (hereinafter simply referred to as “engine”) 6, a transmission 7, and the like is disposed therein. The head pipe 2 is rotatably provided with a front fork 3 having a handle 5 attached to the upper portion thereof, and supports a front wheel 4 that is rotatably attached to the lower end of the front fork 3.

  The handle 5 is provided with a shift switch (not shown) that causes the transmission 7 of the engine 8 to perform a shifting operation by an operation of the driver. The shift switch has a shift up button and a shift down button, not shown. When the driver presses these shift-up buttons, the transmission 7 performs a shift-up operation, and when the shift-down buttons are pressed by the driver, the transmission 7 performs a shift-down operation.

  In the main frame 1, a seat 9 and a fuel tank 9 a are disposed above the engine 8. An ECU 11 (Electronic Control Unit) that controls the operation of each part of the motorcycle 10 is disposed between the seat 9 and the fuel tank 9 a and the engine 8. The ECU 11 controls the operation of the transmission 7 that transmits the power of the transmission gear stage to one engine body 6 by a friction transmission clutch.

  Further, a rear arm 12 extends rearward from a rear end side portion inclined downward in the main frame 1 and joined thereto. The rear arm 12 rotatably holds a rear wheel 13 and a driven sprocket 15 fixed to the rear wheel 13 and wound with a drive chain 14.

(2) Configuration of Engine FIG. 2 is a left side view schematically showing the positional relationship between the shafts in the engine of the motorcycle shown in FIG. 1, and FIG. 3 is a portion indicated by the line AA in FIG. 4 is a cross-sectional view of the engine corresponding to the portion indicated by the line BB in FIG. 2. In FIG. 2, the counterweight, the balancer gear, and the counterweight with gear arranged around the rotation axis of the crankshaft 60 are shown in partial outlines. In addition, the crankshaft in FIG. 3 is shown in a state in which no connecting rod is connected to the crankpins 641, 642, 643, 644 for convenience.

  The engine 8 includes an engine body 6, a transmission 7, and a crankcase 810 and a transmission case 830 to which the engine body 6 and the transmission 7 are attached.

  The engine body 6 includes a crankshaft 60, a camshaft drive unit 65, a generator 66, and a balance shaft 90. The cam shaft drive unit 65, the generator 66 and the balance shaft 90 are driven by the rotation of the crankshaft 60.

  The crankshaft 60 in the engine main body 6 provided in the engine 8 has a rotational couple by arranging a plurality of crankpins 641 to 644. As shown in FIG. 5, the crankshaft 60 is a cross-plane crankshaft in which a number corresponding to a cylinder, here, four crankpins 641 to 644 are arranged in a phase of 90 degrees. In FIG. 5, the crank pins 641 to 644 are arranged so as to surround the journals (621 to 625) when viewed from the axial direction (here, the left and right direction of the vehicle).

  Here, the engine to which such a cross-plane crankshaft 60 is applied is an in-line four-cylinder unequal interval explosion engine, but is not limited thereto. For example, it may be an equidistant explosion, which may be an inline 3-cylinder, in-line 5-cylinder engine, or a V-type 6-cylinder engine or a V-type 8-cylinder engine. Specifically, the crankshaft is effective in a crankshaft that generates a rotational couple when rotating.

  The crankshaft 60 is rotatably disposed in the crankcase 810 of the engine 8 while extending substantially horizontally in the direction (left-right direction) perpendicular to the vehicle front-rear direction below the cylinder head. Specifically, the center portion of the crankshaft 60 is disposed at the approximate center in the left-right direction of the vehicle so as to be located on the vehicle center axis.

  In the engine body 6 (see FIGS. 1 and 2), the crankcase 810 (see FIGS. 3 and 4) that houses the crankshaft 60 has cylinders 671 to 674 that project obliquely upward from the front side. Yes. The cylinders 671 to 674 are arranged side by side along the extending direction of the crankshaft 60 so that the center of the cylinders 671 to 674 is positioned at a substantially central portion in the left-right direction of the vehicle or the engine 8.

  In this engine body 6, four cylinders (four cylinders) 671 to 674 are arranged in two cylinders with the vehicle center plane or the approximate center of the engine 8 in the left-right direction sandwiched between them, and are configured to explode at unequal intervals. Has been. In the engine main body 6, the bore pitch of the four cylinders 671 to 674, that is, the interval BP between the centers of the cylinders 671 to 674 is uniform.

  Here, the crankshaft 60 includes a plurality of counterweights (including a web (hereinafter referred to as “CW (Counter Weight)”) 631 to 638, five journals 621 to 625, and crank pins 641 to 644. It is formed by joining with. Here, the journals 621 to 625 in the crankshaft 60 are connected to the first journal 621, the second journal 622, the third journal 623, the fourth journal 624, and the fifth journal 625 from the other end side (left side) of the crankshaft 60. Called.

  Crank pins 641 to 644 of the cross-plane crankshaft 60 are connected to pistons 68 in the cylinders 671 to 674 via connecting rods 69, respectively.

  Further, in the crankshaft 60, a CW 637 on one end side is processed, and a gear (reducing gear) 639 for outputting the rotational power of the engine body 6 to the outer periphery thereof, that is, a power take-off (PTO) is provided. Is provided. That is, in the crankshaft 60, the CW 637 is a geared CW 637 on one side with respect to the third journal 623 at the center.

  Further, CW (including web) 631 to 638 counteracts the unbalanced force (unbalance) of rotational balance in the crankshaft caused by the inertial force generated by the reciprocating motion of the piston 68 and the connecting rod 69, respectively. Here, a counterweight that counteracts the inertial force of the first cylinder 671 and the second cylinder 672 is set by the CWs 631, 632, 633, and 634. Further, CWs 635, 636, 637, and 638 set a counterweight that counteracts the inertial forces of the third cylinder 673 and the fourth cylinder 674.

  Of the first to fifth journals 621 to 625 serving as the rotation axis in the crankshaft 60, the third journal 623 located in the center portion is subjected to a torsional resonance node by applying a couple of opposite phases to the crankshaft 60. Become. For this reason, the third journal 623 is solid and does not include an oil supply hole in order to ensure strength.

  The first to fifth journals 621 to 625 including the third journal 623 are rotatably supported by journal receiving inner walls (journal receiving portions) 811 to 815 of the crankcase 810. The journal receiving inner walls 811 to 815 are portions that partition the crank chamber communicating with each of the cylinders 671 to 674 in the crankcase 810 in the crankshaft direction. These journal receiver inner walls 811 to 815 rotatably support the first to fifth journals 621 to 625 via bearing portions (metal) 821 to 825. Thereby, the crankshaft 60 is rotatably attached to the crankcase 810.

  In the engine 8, the crankshaft 60 is rotatable in a state where movement in the thrust direction is restricted by the second journal 622 via the thrust receiving portion 680.

  The journal receiving inner walls 811 to 815 are formed by combining the upper case and the lower case constituting the crankcase 810, and the thrust receiving portion 680 is the upper case of the upper case and the lower case constituting the journal receiving inner wall 811. Provided on the side.

  The thrust receiving portion 680 is provided on the crankshaft 60 so as to restrict the movement of the second journal 622 arranged on the other end side opposite to the geared CW 637 in the thrust direction. Counterweights 632 and 633 connected by the second journal 622 supported by the thrust receiving portion 680 are respectively disposed in adjacent crank chambers (a crank chamber communicating with the first cylinder 671 and a crank chamber communicating with the second cylinder 672). To position.

  The thrust receiving portion 680 is configured to receive CW 632 and 633 on both side surfaces parallel to the rotation axis direction of the journal receiving inner wall 812. That is, both side surfaces of the thrust receiving portion 680 are formed as surfaces that are parallel to the axial direction of the opposing side surfaces (thrust receiving surfaces 6321 and 6331) of the CWs 632 and 633 and that are smoothly slidable.

  As a result, even with the cross-plane crankshaft 60 having the geared CW637, the counterweight for canceling the inertia force generated in the fourth cylinder 674 can be set by the CW636 and 638 adjacent to the geared CW637. . That is, it is possible to set the counterweight that counteracts the unbalanced force generated by the rotation of the cross-plane crankshaft 60 by processing the CW636 and 638 without processing the geared CW637 and setting the counterweight. The unbalanced force generated by the rotation of the crankshaft 60 is generated due to the inertial force generated by the reciprocating motion of the piston and connecting rod.

  Therefore, in the crankshaft 60, when the CW on one end side (for example, CW637 or CW638) is a CW with gear, the CW635, 636, 638, or CW635, 636, 637 has three CWs. It is necessary to set 1/2 of the necessary unbalanced moment.

  The CWs 632 and 633 received by the thrust receiving part 680 (specifically, the side face of the thrust receiving part 680 and the side face of the journal receiving inner wall 812) cause the thrust receiving part 680 to contact the thrust receiving faces 6321 and 6331. . The thrust receiving surfaces 6321 and 6331 are opposed to each other with a journal (here, the second journal 642) supported by the thrust receiving portion 680 of the crankcase 810 interposed therebetween. The thrust receiving surfaces 6321 and 6331 received by the thrust receiving portion 680 are opposed to each other and are highly accurate smooth surfaces, and are configured by finishing the side surface of the target CW by polishing.

  A thrust receiving portion in a conventional crankshaft is sandwiched between a geared CW and a CW opposite to the geared CW (referred to as “opposing CW”), and supports a journal connecting the geared CW and the opposite CW. Was provided. In this configuration, it is necessary to form smooth surfaces on both the geared CW sandwiching the thrust receiving portion and the geared CW and the opposing CW.

  In such an engine body with a uniform bore pitch, a thrust receiving portion, a geared CW received by the thrust receiving portion, and a CW opposed to the geared CW are disposed within a predetermined range. For this reason, it is necessary to reduce the thickness (length in the axial direction) of each CW (CW with gear, opposite CW) that comes into contact with the thrust receiving portion.

  For example, when the crankshaft that supports the journal between the geared CW and the opposed CW is used in the engine configuration of the present embodiment, the thrust receiving unit receives the journal 624 coupled to the geared CW637 at the thrust receiving unit. It becomes. In this case, the thicknesses of the CWs 636 and 637 are thinner than those of the CWs 631 to 635 and 638. This is due to the fact that the base of the journal receiving inner wall with the thrust receiving part (corresponding to the base of the thrust receiving part) is thicker (thickness in the axial direction) than the base of the journal receiving inner wall without the thrust receiving part.

  The CW thrust received by the thrust receiving portion on the thrust surface is positioned together with the crank pin between the journal receiving inner walls arranged corresponding to a certain bore pitch. Therefore, the thickness (axial length) of the CW thrust-received on the thrust surface is reduced so as not to come into contact with the base of the inner wall where the thrust-receiving portion is located during rotation.

  6 is a cross-sectional view showing the positional relationship between the journal receiving inner wall and the CW, FIG. 6A is a cross-sectional view of the journal receiving inner wall having a thrust receiving portion and a CW having a thrust surface, and FIG. 6B is a drawing of the thrust receiving portion. It is sectional drawing of CW without a journal receiving inner wall and a thrust surface. FIG. 7 is a cross-sectional view in which each journal receiving inner wall of FIG. 6A and FIG. 6B is overlapped with CW, and shows a difference in thickness of CW having a thrust surface. 6 and 7 is a rotation shaft of the crankshaft, and JCL indicates a center plane of the journal receiving inner wall (journal receiving portion).

  A journal receiving inner wall SRJ having a thrust receiving portion 680 shown in FIG. 6A has a thrust receiving portion 680 formed at a pointed portion that receives the journal. Note that the journal receiving inner wall SRJ has a thickness in the direction of the rotation axis CL that is thin on the tip end side in order to remove the crankcase (for example, the crankcase 810) downward in the figure when die-cast molding, It is thicker towards the base. In the figure, the side surface SRJS of the journal receiving inner wall SRJ is inclined in a direction away from the center plane JCL from the pointed portion toward the base. And the thrust receiving part 680 is formed in the side surface of a pointed part by processing the thinned pointed part so that it may become a smooth surface orthogonal to the rotating shaft CL. Specifically, a portion indicated by a broken line H is processed to provide a thrust receiving surface 6801 as a thrust receiving portion. In the journal receiving inner wall SRJ having such a thrust receiving portion 680, a CW having a thrust surface (CW with thrust surface) is disposed along the side surface SRJS on which the thrust receiving surface 6801 is formed. The thrust surface CW has a thrust surface abutting against the thrust receiving surface 6801, and the side surface SCWS of the thrust surface CW is connected to the side surface SRJS following the broken line H of the journal receiving inner wall SRJ in the vicinity of the outer periphery of the thrust surface CW. In order to prevent contact with the substrate, it has a predetermined thickness W12 in the rotation axis direction.

The journal receiving inner wall RJ without a thrust receiving portion shown in FIG. 6B also has a thickness in the direction of the rotation axis CL in order to die downward in the drawing when the crankcase (for example, the crankcase 810) is die-cast molded. The tip end side is thin and thicker toward the base.
In FIG. 6B, the side surface RJS of the journal receiving inner wall RJ is inclined in a direction away from the center plane JCL from the pointed portion toward the base portion. The thrust surfaceless CW is configured to have side surfaces along such side surfaces RJS. This CW is a CW without a thrust surface (no thrust surface CW). The thrust surface-less CW is the minimum provided around the joint with the journal J in order to avoid the thickness W21 of the CW body and the grinding wheel when grinding the journal J from contacting the side surface CWS of the thrust surface CW. Limit thickness W22.

  When comparing the positions of the side surfaces SRJS and RJS of these journal receiving inner walls SRJ and RJ, as shown in FIG. 7, the journal receiving inner wall RJ without the thrust receiving portion 680 has a pointed end thinner than the thickness of the journal receiving inner wall SRJ. The proximal end is thin.

  Therefore, in the CW facing these journal receiving inner walls SRJ and RJ, a difference occurs in the thickness of the CW main body. Specifically, the thickness of the CW without a thrust surface (thickness in the rotation axis direction) is W21 + W22, and the thickness of the CW with thrust surface is W11 + W12. Of these thicknesses, when comparing the thicknesses W12 and W22 of the CW main body as the weight setting target location in the CW, the thickness W22 of the CW main body without the thrust surface CW is thicker. In other words, the CW with thrust surface is thinner than the CW without thrust surface.

  A configuration in which the base of the inner wall of the journal receiving portion having the thrust receiving portion is thicker than the base portion of the other inner wall of the journal receiving portion is also shown in FIGS. That is, in the journal receiving inner wall 822 provided with the thrust receiving portion 680, the base portion 681 of the thrust receiving portion 680 is configured to be thicker than the base portions of the other journal receiving inner walls 821, 823 to 825. Note that the base 681 shown in FIGS. 9 and 10 is configured in the same manner.

  Moreover, since CW with a gear has a structure which has a gear in the outer periphery, the outer periphery in which a gear is formed needs to be an outer periphery without a missing part. Thereby, it is difficult to set a counterweight for canceling the unbalanced force (unbalance) of rotation balance in the crankshaft for the geared CW. The CW that is set by compensating for the unbalance that is insufficient in the CW with gear is the CW that faces the CW with gear, but this CW is the above-mentioned counter CW, and the thickness is reduced. Setting for canceling is difficult. Note that this setting is performed so as to be ½ of the inertial force due to the piston motion as described above.

  In view of these, when the crankshaft in which the thrust receiving portion supports the journal between the geared CW and the opposed CW is applied to the engine configuration of the present embodiment, the fourth journal 624 of the crankshaft 60 is received by the thrust receiving portion. It becomes composition. In this case, even if the CW 638, 635, and 636 have low efficiency in generating the unbalanced moment per weight, it is necessary to set the necessary unbalanced moment by increasing the weight by increasing the CW width. Alternatively, for example, when the CW 638 is a PTO configuration, that is, when the CW 638 is a geared CW, the unbalanced moment is set by CW 635, 636, 637. However, the thicknesses of CW636 and CW637 are thinner than CW631 to 635 and 638, and CW635, 636 and 637 have a smaller moment arm length than CW638. For this reason, it is necessary to adjust the weight by increasing the CW width of the CW 635, 636, 637 or increasing the outer diameter. As a result, the weight of CW is increased, and the weight of the crankshaft itself is increased.

  On the other hand, in the engine 8 of the present embodiment, the thrust receiving portion 680 is received by the second journal 622 on the other end portion side opposite to the geared CW 637 provided on the one end portion side of the crankshaft 60. ing.

  That is, the thrust receiving portion 680 is configured to receive the CW on the opposite side of the geared CW 637 with the central portion of the crankshaft 60 interposed therebetween.

  For this reason, the setting for canceling the unbalanced moment can be arbitrarily made without being influenced by the shape of the geared CW 637.

  Specifically, the thrust receiving portion 680 is received by the second journal 622 on the other end side of the crankshaft 60. Thereby, in the crankshaft 60, the thickness of CW636, 637 of the one end part side can be increased, and the thickness of CW632, 633 can be reduced. The opposing surfaces of CW 632 and 633 can be polished to be processed into thrust receiving surfaces 6321 and 6331. Therefore, even if the outer peripheral portion of the CW 637 or CW 638 is the reduction gear 639, the unbalance is efficiently generated by increasing the thickness of the CW 636 and 637. In addition, since the CW 631 to 634 does not have a PTO (no reduction gear is attached), it is sufficient to efficiently generate an unbalanced moment with the four CWs 631 to 634, and the weight of the entire crankshaft can be suppressed.

  The crankshaft 60 is rotated around the journal receiving inner walls 811 and 815 by the first and fifth journals 621 and 625 on both ends in a state where both ends protrude from the journal receiving inner walls 811 and 815 of the crankcase 810 to the left and right. It is attached movably.

  A cam shaft driving portion 65 is attached to one end portion (right end portion) of the left and right shaft end portions of the crankshaft 60. A generator 66 is attached to the other end (left end) of the crankshaft 60 on the side where the camshaft drive unit 65 is not attached. The camshaft drive unit 65 and the generator 66 are driven by the rotation of the crankshaft 60, respectively.

  In the camshaft drive unit 65, the cam chain 652 (see FIG. 4) rotates as the cam gear 651 fixed to the right end of the crankshaft 60 rotates.

  As the cam chain 652 rotates, the cam valve shaft 654 wound around the cam chain 652 via a gear rotates. Thus, in the engine body 6, the intake and exhaust valves (in FIG. 4, a cross section corresponding to the BB cross section in FIG. 2 is shown by the plugs 656 in the two cylinders on the left side in the drawing, as shown in FIG. In the cross section of the two cylinders on the middle right side, the intake valve 655a and the exhaust valve 655b are partially shown). The cam shaft driving unit 65 is covered with a cam shaft driving unit cover (cam chain cover).

  The generator 66 includes a rotor 661 fixed to the crankshaft 60 and a stator 662 disposed on the inner periphery of the rotor 661. The generator 66 is covered with a generator cover.

  A balancer drive gear (balance gear) 91, which is another gear for transmitting rotational force to the balance shaft 90, is fixed by press-fitting to the other end (left end) side of the crankshaft 60 where the generator 66 is disposed. ing. The balance gear 91 is disposed in a position adjacent to the CW 631 disposed on the other end side of the crankshaft 60 by being press-fitted into the shaft portion of the crankshaft 60. Here, the balance gear 91 is arranged in a crank chamber that is partitioned by journal receiving inner walls 811 and 812 and communicates with the first cylinder 671. The balance gear 91 is fixed to the crankshaft 60 by press fitting. For this reason, the strength of the crankshaft 60 itself is not reduced.

  The balance gear 91 meshes with a balancer driven gear 93 of the balance shaft 90 that is rotatably accommodated in the crankcase 810.

  The balance shaft 90 is disposed in parallel with the crankshaft 60. The balance shaft 90 functions as a CW together with the crankshaft 60 and is arranged corresponding to a couple generated in the crankshaft 60, and prevents this couple from being transmitted to the vehicle as vibration.

  The balance shaft 90 is shorter than the crankshaft 60 and is disposed in the vicinity of the crankshaft 60. Here, the balance shaft 90 is disposed in front of the crankshaft 60 and the transmission and below the cylinders 671 to 674 of the engine body 6 (see FIG. 3). The balance shaft 90 is arranged close to the generator 66 in the engine 8 in plan view with reference to the vehicle center line (corresponding to the vehicle center plane). By this position, the left and right weight balance in the engine 8 can be adjusted.

  The crankshaft 60 transmits the rotational force to the transmission 7 through the reduction gear 639 of the CW 637 with gear.

  The transmission 7 is disposed behind the engine body 6 and varies the rotational power transmitted from the crankshaft 60 and transmits it to the rear wheel 13 side. Although not shown, the variable operation in the transmission 7 is performed by a shift mechanism (not shown). The shift mechanism has a shift cam that is rotationally driven by a motor (not shown). A groove is formed on the outer periphery of the shift cam. In this groove, the base end of the shift fork is provided movably along the groove. The shift fork is moved by the rotation of the shift cam, and the transmission gear stage of the transmission gear group 75 of the transmission 7 is appropriately changed.

  The transmission 7 includes a main shaft 71, a reduction gear 72, a drive shaft (output shaft) 73, a clutch 74, and a transmission gear group 75.

  The main shaft 71 and the drive shaft (output shaft) 73 are disposed in the mission case 830.

  The main shaft 71 is disposed in parallel with the drive shaft 73 and in parallel with the crankshaft 60 that is disposed substantially horizontally in a direction orthogonal to the vehicle. The main shaft 71 is connected to the clutch 74 at one end (right side) end.

  The clutch 74 disconnects or connects the rotational power transmitted from the crankshaft 60 to the main shaft 71. The clutch 74 is connected to a pull rod 77 of a clutch actuator (not shown). The operation of the clutch 74 is controlled by the ECU 11 via a clutch actuator.

  The gear shift performed on each gear of the transmission gear group 75 in the transmission 7 is performed by a shift fork that is movable by rotation of a shift cam in a shift mechanism (not shown). The shift fork performs a gear shift by moving each spline gear in the transmission gear group 75 of the transmission 7 in the axial direction. Similar to the clutch 74, the shift mechanism is controlled by the ECU 11 (see FIG. 1). The clutch 74 and the shift mechanism perform power transmission via each gear of each transmission gear based on an input of shift change.

  The reduction gear 72 meshes with the reduction gear 639 of the crankshaft 60. By this engagement, the power transmitted from the geared CW 637 at one end of the crankshaft 60 to the reduction gear 72 can be transmitted from the one end of the crankshaft 60 to the main shaft 71 via the clutch 74. Yes.

  In the transmission 7, the power transmitted to the main shaft 71 is transmitted to the drive shaft 73 disposed rearward by appropriately selecting each gear of the transmission gear group 75. A drive chain 14 (see FIG. 1) wound around a driven sprocket 15 provided on the rotating shaft of the rear wheel 13 is wound around a sprocket 76 fixed to the other end (left end) of the drive shaft 73. Has been. When the sprocket 76 rotates as the drive shaft 73 rotates, the driving force is transmitted to the rear wheel 13 (see FIG. 1), which is a driving wheel, via the drive chain 14 (see FIG. 1).

  Thus, in the motorcycle 10 using the transmission 7, the driving force of the engine body 6 from the crankshaft 60 is output from the clutch 74, the main shaft 71, and the transmission gear group 75 via the drive shaft 73.

  Thus, according to the motorcycle 10 including the engine body 6 that is the reciprocating internal combustion engine of the present embodiment, even when the cross-plane crankshaft 60 is used, an unbalanced moment is efficiently generated, and The weight of the crankshaft 60 itself can be easily reduced. Thus, by reducing the weight of the crankshaft 60 itself, the weight of the engine body 6 itself can be suppressed.

  Specifically, when the cross-plane crankshaft 60 is used in the in-line four-cylinder engine body 6, a thrust receiving portion 680 is provided in a portion of the crankcase 810 that receives the second journal 622 of the crankshaft 60. The second journal 622 is located on the other end side with respect to the central portion of the crankshaft 60 provided with the geared CW 637 at one end. Thus, by providing the thrust receiving portion 680 on the portion that receives the second journal 622, that is, the journal receiving inner wall 812, the movement of the crankshaft 60 in the thrust direction is restricted. Accordingly, the thickness of the CWs 636 and 637 on one end side of the crankshaft 60 can be increased, and the thickness of the CWs 632 and 633 on which the thrust surfaces 6321 and 6331 received by the thrust receiving part 680 are formed can be reduced. Thereby, even if the outer peripheral part of CW637 or CW638 is a reduction gear, the unbalanced moment is efficiently generated by increasing the thickness of CW636 and 637. In addition, CW 631-634 does not have a PTO (no reduction gear). For this reason, what is necessary is just to generate | occur | produce an unbalance moment efficiently by four CW631-634. Accordingly, the crankshaft 60 as a whole can reduce the weight of the crankshaft 60 itself, and even the engine body 6 including the cross-plane crankshaft 60 can efficiently generate an unbalanced moment, and the engine body 6 itself Weight can be suppressed.

(Embodiment 2)
8 is a left side view of the engine as the reciprocating internal combustion engine according to the second embodiment, FIG. 9 is an axial cross-sectional view of the engine corresponding to the portion indicated by the line CC in FIG. 8, and FIG. FIG. 9 is a cross-sectional view of the engine corresponding to the portion indicated by the line DD in FIG. 8.

  An engine 8A as a reciprocating internal combustion engine in the second embodiment includes an engine main body 6A, a transmission 7A, a crankcase 810A to which the engine main body 6A and the transmission 7A are attached, and a transmission case 830A.

  The engine body 6A is a reciprocating engine. The engine body 6A is provided integrally with a transmission (dual clutch transmission) 7A including a plurality of friction transmission clutches 741 and 742 as the engine 8A. The dual-clutch transmission 7A uses a plurality of clutches, here the first clutch 741 and the second clutch 742, to alternately transmit power to the odd-numbered and even-numbered shift gears, thereby transmitting power. Realizes seamless shifting.

  The engine main body 6A according to the second embodiment is an in-line four-cylinder reciprocating engine similar to the engine main body 6 of the first embodiment, and can be mounted in place of the engine 8 in the motorcycle 10 of the first embodiment. is there. The engine 8A differs from the engine 8 only in the configuration of the transmission 7A and the components related thereto, and the other components and operational effects are the same. Therefore, in engine 8A, the same components as those of engine 8 corresponding to the first embodiment shown in FIG.

  Similarly to the engine body 6, the engine body 6A includes a cross-plane crankshaft 60A, a camshaft drive unit 65, a generator 66, and a balance shaft 90A, as shown in FIGS. The cam shaft drive unit 65, the generator 66, and the balance shaft 90 are driven by the rotation of the crankshaft 60A. Note that the crankshaft 60 </ b> A in FIG. 9 is a cross-plane crankshaft similar to the crankshaft 60. Therefore, the arrangement of the crank pins 641, 642, 643, 644 on the crankshaft 60A is as shown in FIG. 5 as in the first embodiment.

  The crankshaft 60A is disposed in the crankcase 810A in the left-right direction. A hollow transmission case 830A is provided adjacent to the crankcase 810A, and the transmission 7A is disposed in a region including the crankcase 810A and the transmission case 830A. In the crankcase 810A, cylinders 671 to 674 are disposed so as to project obliquely upward on the front side. These cylinders 671 to 674 are arranged side by side along the extending direction of the crankshaft 60 </ b> A so that the center of the cylinders 671 to 674 is positioned at a substantially central portion in the left-right direction of the vehicle or the engine 8. The cylinders (four cylinders) 671 to 674 are arranged so as to be divided into two cylinders with the vehicle center plane or the approximate center in the left-right direction of the engine 8 interposed therebetween, and are configured to explode at unequal intervals. The bore pitches of the cylinders 671 to 674, that is, the intervals between the centers of the cylinders 671 to 674 are uniform.

  Below such cylinder heads of the cylinders 671 to 674, the crankshaft 60 </ b> A is rotatably disposed while extending substantially horizontally in a direction (left-right direction) orthogonal to the front-rear direction of the vehicle.

  As with the crankshaft 60 of the first embodiment, the crankshaft 60A has a rotational couple by arranging a plurality of crankpins. Here, the crankshaft 60A is a cross-plane crankshaft in which the number corresponding to the cylinder, here, four crankpins 641 to 644 are arranged in a phase of 90 degrees (see FIG. 5). An engine to which the cross-plane crankshaft 60A is applied is the same as an engine to which the crankshaft 60 is applied.

  Like the crankshaft 60, the crankshaft 60 </ b> A in the engine body 6 </ b> A has a plurality of counterweights (including a web (hereinafter referred to as “CW (Counter Weight)”) 631 to 636, 637 </ b> A, and 638 </ b> A. The crankshaft 60A is formed by joining CW 631 to 636, 637A, and 638A with five journals 621 to 625 and crank pins 641 to 644. Here, the journals 621 to 625 in the crankshaft 60A are connected to the first journal 621, the second journal 622, the third journal 623, the fourth journal 624, and the fifth journal 625 from the other end side (left side) of the crankshaft 60A. Called. In the crankshaft 60A, from the other end side (left side), the first journal 621, CW631, crankpin 641, CW632, second journal 622, CW633, crankpin 642, CW (in detail Web) 634, third journal 623, CW (in detail Web) 635, crankpin 643, CW636, fourth journal 624, CW637A, crankpin 644, CW638A, and fifth journal 625 are arranged side by side.

  Crank pins 641 to 644 of the crankshaft 60 are connected to pistons 68 in cylinders (first, second, third, and fourth cylinders in order from the left side) 671 to 674 via connecting rods 69, respectively.

  Further, in the crankshaft 60A, a CW 638A located on the most end side (right side) is processed, and the rotational power of the engine body 6A is output to the outer periphery thereof, that is, a gear (Power Take Off: PTO) ( (Reduction gear) 639 is provided. That is, the crankshaft 60 </ b> A has a configuration in which a geared CW638 </ b> A is disposed on one side with respect to the third journal 623 at the center. The geared CW 638A meshes with the first reduction gear 721 of the first clutch 741 of the transmission 7A and outputs the rotational power of the engine. Due to the engagement between the gear 639 of the geared CW638A and the first reduction gear 721, the rotational power of the engine body 6A from the geared CW638A on one end (right end) side of the crankshaft 60A is changed to the first reduction gear. 721. The rotational power transmitted to the first reduction gear 721 is transmitted to the first main shaft 711 via the first clutch 741.

  CW (including web) 631 to 636, 637A, and 638A cancel the unbalanced force (unbalance) of the rotational balance in the crankshaft caused by the inertial force generated by the reciprocating motion of the piston 68 and the connecting rod 69, respectively. It is. Since these details are the same as those of CW (including web) 631 to 638 in the crankshaft 60, description thereof will be omitted. The geared CW638A corresponds to the geared CW637, and the CW637A corresponds to the CW638. Further, the first to fifth journals 621 to 625 serving as the rotation axis in the crankshaft 60 </ b> A also have the same operational effects as those of the crankshaft 60, and the description thereof is omitted.

  These first to fifth journals 621 to 625 are pivotally supported by journal receiving inner walls 811 to 815 of the crankcase 810A via bearing portions (metals), whereby the crankshaft 60A is mounted on the crankcase 810A. It is pivotally attached.

  Further, the crankshaft 60A is disposed in a state in which both end portions thereof protrude left and right from the journal receiving inner walls 811 and 815 of the crankcase 810A. The crankshaft 60A is attached to the crankcase 810A by first and fifth journals 621 and 625 so as to be rotatable on journal receiving inner walls 811 and 815 via bearings.

  A cam shaft drive unit 65 is attached to the other shaft end portion (left end portion) of the left and right shaft end portions of the crankshaft 60A. Further, a generator 66 is attached to the end of the crankshaft 60A on the side where the camshaft drive 65 is not attached. The camshaft drive unit 65 and the generator 66 are driven by rotation of the crankshaft 60A.

  In the camshaft drive unit 65, the cam chain 652 (see FIG. 9) rotates as the cam gear 651 fixed to the left end of the crankshaft 60A rotates.

  By rotation of the cam chain 652, as shown in FIG. 10, the cam valve shaft 654A wound around the cam chain 652 via a gear rotates. Thereby, in the engine body 6A, the intake and exhaust valves (in FIG. 10, the cross section corresponding to the DD cross section in FIG. 8 is shown by the plugs 656 in the right two cylinders in FIG. In the cross section of the two cylinders on the left side, the intake valve 655a and the exhaust valve 655b are partially shown). The cam shaft driving unit 65 is covered with a cam shaft driving unit cover (cam chain cover).

  The generator 66 has a rotor 661 fixed to the crankshaft 60 </ b> A and a stator 662 disposed on the inner periphery of the rotor 661. The generator 66 is covered with a generator cover.

  A balancer drive gear (balance gear) 91A for transmitting rotational force to the balance shaft 90A is fixed by press-fitting to one end of the crankshaft 60A where the generator 66 is disposed. Since the balance gear 91A is attached to the crankshaft 60A by press fitting, the strength of the crankshaft 60A is not reduced. The balancer drive gear 91 </ b> A is partitioned by the journal receiving inner walls 814 and 815 and is disposed in the crank chamber communicating with the fourth cylinder 674.

  The balance gear 91A meshes with the balancer driven gear 93 of the balance shaft 90A that is rotatably accommodated in the crankcase 810A.

  The balance shaft 90A is disposed in parallel with the crankshaft 60A. The balance shaft 90A has the same function as the balance shaft 90 in the engine body 6. That is, the balance shaft 90A functions as a CW together with the crankshaft 60A, and is disposed corresponding to the couple generated in the crankshaft 60A, and prevents this couple from being transmitted to the vehicle as vibration.

  The balance shaft 90A is shorter than the crankshaft 60A and is disposed in the vicinity of the crankshaft 60A. Here, the balance shaft 90A is disposed in front of the crankshaft 60A and the transmission and below the cylinders 671 to 674 of the engine body 6A (see FIG. 10). The balance shaft 90A is arranged close to the generator 66 side with respect to the vehicle center line (corresponding to the vehicle center plane) in plan view in the engine 8A. By this position, the left and right weight balance in the engine 8A can be adjusted.

  In the crankshaft 60A, an external gear (another gear) 602 having a gear groove formed on the outer periphery is fixed to the other end side of the shaft portion by press-fitting. The external gear 602 is disposed in a position adjacent to the CW 631 disposed on the other end side of the crankshaft 60A by being press-fitted into the shaft portion of the crankshaft 60A. Here, the external gear 602 is arranged in a crank chamber that is partitioned by journal receiving inner walls 811 and 812 and communicates with the first cylinder 671. Since the external gear 602 is fixed to the crankshaft 60A by press fitting, the strength of the crankshaft 60A itself is not reduced.

  This external gear 602 has a function of outputting the rotational power of the engine main body 6A, similar to the geared CW638A, and its gear groove is the same as the gear 639 of the geared CW638A. Here, the external gear 602 meshes with the second reduction gear 722 of the second clutch 742, and outputs the rotational power of the engine body 6A to the second clutch 742. More specifically, the rotational power of the engine body 6A from the external gear 602 on the other end (left end) side of the crankshaft 60A is changed to the second by the meshing of the external gear 602 and the second reduction gear 722. This is transmitted to the reduction gear 722. The rotational power transmitted to the second reduction gear 722 is transmitted to the second main shaft 712 of the transmission 7A via the second clutch 742.

  The transmission device 7A is provided in the transmission case 830A at the rear of the engine so that the approximate center in the full width in the left-right direction of the transmission device 7A and the center in the left-right direction of the motorcycle 10, that is, the vehicle center plane coincide with each other. . The vehicle center plane means a vertical plane passing through the vehicle center line in a state where the vehicle stands upright with respect to the horizontal plane. The transmission 7A changes the rotational power of the engine body 6A transmitted from the crankshaft 60A and transmits it to the rear wheel 13 side.

  The transmission 7A includes a first main shaft 711, a second main shaft 712, a first reduction gear 721, a second reduction gear 722, a drive shaft 73, a first clutch 741, and a second clutch 742. And a transmission gear group 75.

  The first main shaft 711, the second main shaft 712, and the drive shaft 73 are rotatably disposed in the mission case 830A in parallel with the crankshaft 60A that is disposed substantially horizontally in a direction orthogonal to the vehicle.

  The first main shaft 711 and the second main shaft 712 have the same outer diameter, are arranged side by side on the same axis, and rotate independently of each other.

  The first clutch 741 and the second clutch 742 are arranged on the left and right sides of the vehicle so as to sandwich the first main shaft 711 and the second main shaft 712, respectively.

  Specifically, the first and second main shafts 711 and 712 have their distal ends opposed to each other at the approximate center in the mission case 830A, and the base ends thereof in both directions of the mission case 830A. It protrudes from the left and right.

  In the first main shaft 711, a first clutch 741 is connected to a base end portion protruding from the side (right side) of the mission case 830A.

  In the second main shaft 712, a second clutch 742 is connected to a base end portion protruding from the side (left side) of the mission case 830A.

  The first clutch 741 disconnects or connects the rotational power of the engine body 6A transmitted from the crankshaft 60A to the first main shaft 711.

  In the first clutch 741, a clutch outer provided integrally with the first reduction gear 721 is rotatably provided on the outer periphery of the first main shaft 711. In addition, a clutch inner that is disposed inside the clutch outer and opens (cuts) / fastens (connects) with the clutch outer is fixed to a base end portion (right end portion) of the first main shaft 711. The first clutch 741 disconnects or connects the rotational power of the engine body 6A by opening and fastening the clutch outer and the clutch inner. The first clutch 741 is connected to a pull rod 77 of a first clutch actuator (not shown). The operation of the first clutch 741 is controlled by the ECU 11 (see FIG. 1) via a first clutch actuator (not shown). The first clutch 741 is connected to the odd-numbered gear stages (first, third, and fifth) of the transmission gear group 75 across the first main shaft 711 and the drive shaft 73. Thus, rotational power is output to the drive shaft 73 and transmitted to the rear wheels.

  The second clutch 742 cuts or connects the rotational power of the engine body 6A transmitted from the crankshaft 60A to the second main shaft 712 via the second reduction gear 722. The second clutch 742 is configured symmetrically with the first clutch 741. In the second clutch 742, a second reduction gear 722 and a clutch outer integrated with the second reduction gear 722 are rotatably provided on the outer periphery of the second main shaft 712. In addition, a clutch inner that is disposed inside the clutch outer and opens (cuts) and fastens (connects) with the clutch outer is fixed to a base end portion (left end portion) of the second main shaft 712. The second clutch 742 disconnects or connects the rotational power of the engine body 6A by opening and closing the clutch outer and the clutch inner. The second clutch 742 is connected to a pull rod 772 of a second clutch actuator (not shown). The operation of the second clutch 742 is controlled by the ECU 11 (see FIG. 1) via a second clutch actuator (not shown). The second clutch 742 is connected to the transmission gear group 75 through even-numbered gear stages (second stage, fourth stage, and sixth stage) that are disposed across the second main shaft 712 and the drive shaft 73. Thus, rotational power is output to the drive shaft 73 and transmitted to the rear wheel 13.

  The gear shift performed on each gear of the transmission gear group 75 in the transmission 7A is performed by a shift fork that is movable by rotation of a shift cam in a shift mechanism (not shown). The shift fork performs a gear shift by moving each spline gear in the transmission gear group 75 of the transmission 7A in the axial direction. As with the first clutch 741 and the second clutch 742, the operation of the shift mechanism is controlled by the ECU 11 (see FIG. 1). The first clutch 741, the second clutch 742, and the shift mechanism are connected to and disconnected from the first clutch 741, the second clutch 742, and the shift gear stages corresponding to the connection / disconnection operation based on the shift change input. Power is transmitted through gears.

  In the engine 8A configured as described above, the crankshaft 60A is rotatable in a state in which movement in the thrust direction is restricted by the second journal 622 via the thrust receiving portion 680A.

  The journal receiving inner walls 811 to 815 are formed by combining the upper case and the lower case constituting the crankcase 810A. The thrust receiving portion 680A is provided on the upper case side among the lower case and the upper case constituting the journal receiving inner walls 811 to 815. The thrust receiving portion 680A is configured to receive the thrust receiving surfaces 6321 and 6331 of the opposing CWs 632 and 633 on both side surfaces thereof.

  That is, the thrust receiving portion 680A is provided on the journal receiving inner wall 812 so as to support the second journal 622 disposed on the other end side opposite to the geared CW 638A on the crankshaft 60A. The thrust receiving portion 680A that supports the second journal 622 abuts against the thrust receiving surfaces 6321 and 6331 of the CWs 632 and 633 on both side surfaces thereof, and restricts movement in the thrust direction.

  Thereby, even if it is cross plane type crankshaft 60A provided with CW638A with a gear, the effect similar to Embodiment 1 can be acquired.

  That is, the thrust receiving portion 680A is configured to receive the CW on the side opposite to the geared CW 638A with the central portion of the crankshaft 60A interposed therebetween.

  For this reason, the setting for canceling the unbalanced moment can be arbitrarily made without being influenced by the shape of the geared CW638A.

  Specifically, the thrust receiving portion 680A is received by the second journal 622 on the other end side of the crankshaft 60A. Thereby, in the crankshaft 60A, the thickness of CW636 and 637A of the one end part side can be increased, and the thickness of CW632 and 633 can be reduced. The opposing surfaces of CW 632 and 633 can be polished to be processed into thrust receiving surfaces 6321 and 6331. Therefore, even if the outer peripheral portion of CW637A or CW638A is a reduction gear, an unbalance is efficiently generated by increasing the thickness of CW636 and 637A. In addition, since the CW 631 to 634 does not have a PTO (no reduction gear is attached), it is sufficient to efficiently generate an unbalanced moment with the four CWs 631 to 634, and the weight of the entire crankshaft can be suppressed.

  Thus, according to the motorcycle including the engine body 6A that is the reciprocating internal combustion engine of the present embodiment, even when the cross-plane crankshaft 60A is used, an unbalanced moment is efficiently generated and the crank The weight of the shaft 60A itself can be easily reduced. Thus, by reducing the weight of the crankshaft 60A itself, the weight of the engine body 6A itself can be suppressed.

  Specifically, when the cross-plane crankshaft 60A is used in an in-line four-cylinder engine body 6A, a thrust receiving portion 680A is provided in a portion of the crankcase 810A that receives the second journal 622 of the crankshaft 60A. The second journal 622 is located on the other end side with respect to the central portion of the crankshaft 60A having the geared CW 638A at one end. Thus, by providing the thrust receiving portion 680A on the portion receiving the second journal 622, that is, the journal receiving inner wall 812, the movement of the crankshaft 60A in the thrust direction is restricted. As a result, similar to the engine body 6 of the first embodiment, the CW 636 and 637A on one end side of the crankshaft 60A are increased in thickness, and a thrust surface (6321 etc.) received by the thrust receiving portion 680A is formed. , 633 can be reduced in thickness. Therefore, even if the outer peripheral portion of the CW 638A is a reduction gear, an unbalance is efficiently generated by increasing the thickness of the CW 636 and 637A. In addition, since the CW 631 to 634 does not have a PTO (no reduction gear is attached), it is sufficient to efficiently generate an unbalanced moment with the four CWs 631 to 634, and the weight of the entire crankshaft can be suppressed.

  The engine may be any engine as long as it has a crankshaft that generates an unbalanced moment (couple) due to the arrangement of the crankpins.

<Modification>
FIG. 11 is a schematic view showing a modified example of an engine having an engine as a reciprocating internal combustion engine according to the present invention.

  An engine 8B shown in FIG. 11 has an engine body 6B, a transmission 7B, and a crankcase 810B to which the engine body 6B and the transmission 7B are attached.

  In the engine 8B, in the twin clutch transmission 7B provided with the engine body 6B having the cross-plane crankshaft 60B, a plurality of clutches are arranged adjacent to one end side of the main shaft. The engine 8B as a modification is mounted on a motorcycle having a limited mounting space, like the engines 8 and 8A of the embodiments. The configuration of the engine main body 6B in the engine 8B is the same as that of the engine main body 6A of the second embodiment, and a description thereof will be omitted.

  The crankshaft 60B in the engine 8B is the same as the crankshaft 60A of the second embodiment. That is, in the crankshaft 60B, the rotational power of the engine is output to the outer periphery of the CW638B disposed on one end side of the crankshaft 60B among the plurality of CW631 to 636, 637B, and 638B that are spaced apart in the axial direction. A gear 639 is provided.

  The crankcase 810B in the engine 8B has the same configuration as the crankcase 810A, and has a thrust receiving portion 680B that restricts the movement of the crankshaft 60B in the thrust direction.

  In the crankcase 810B, the thrust receiving portion 680B is provided on the journal receiving inner wall 812 disposed on the other end side of the crankshaft 60B. The thrust receiving portion 680B is provided in the upper crankcase that constitutes the journal receiving inner wall 812, as in the second embodiment.

  Such a geared CW638B of the crankshaft 60B meshes with a reduction gear 721B of the transmission 7B.

  The reduction gear 721B is rotatably mounted on the outer periphery of one end portion (right end portion) of the main shaft portion which is rotatably inserted into the second main shaft 712B and is made into a double structure in the first main shaft 711B. ing. The reduction gear 721B is provided integrally with each of the clutch outers of the plurality of clutches 741B and 742B, and rotates around the main shaft portion. In each of the clutches 741B and 742B, a clutch inner that can be engaged with the clutch outer is fixed to one end portion (right end portion) of each of the first main shaft 711B and the second main shaft 712B.

  The clutches 741B and 742B are hydraulic normal release clutches. That is, in the normal state, each clutch 741B, 742B is a state in which the drive plate of the clutch outer on the drive shaft side and the driven plate of the clutch inner on the driven shaft side are released, that is, separated using a return spring. It becomes. In these clutches 741B and 742B, there are provided pressurizing chambers to which a hydraulic fluid (ATF: Automatic Transmission Fluid) dedicated to the clutch is supplied. The clutch piston moves. By the movement of the piston, in each clutch, the drive plate of the clutch outer and the driven plate of the clutch inner are connected or disconnected, that is, the clutches 741B and 742B are connected and disconnected. The clutch 741 </ b> B is connected to an odd number of gear stages (first stage, third stage, and fifth stage) of the transmission gear group 75 across the first main shaft 711 </ b> B and the drive shaft 73. Rotational power is output to the drive shaft 73. Thereby, the rotational power is transmitted to the rear wheel via the sprocket 76. The clutch 742 </ b> B is connected to the transmission gear group 75 through even-numbered gear stages (second stage, fourth stage, and sixth stage) that are disposed across the second main shaft 712 </ b> B and the drive shaft 73. Rotational power is output to the drive shaft 73 and transmitted to the rear wheels via the sprocket 76.

  Thus, according to the motorcycle 10 including the engine body 6B that is the reciprocating internal combustion engine of the present embodiment, even when the cross-plane crankshaft 60B is used, an unbalanced moment is efficiently generated, and The weight of the crankshaft 60B itself can be easily reduced. Thus, by reducing the weight of the crankshaft 60B itself, the weight of the engine body 6B itself can be suppressed.

  In addition, even if the reciprocating internal combustion engine in each embodiment has a configuration including a V-type engine body, in the V-type engine, cylinders in one bank are set to have a constant bore pitch, that is, the distance between the centers of the cylinders is fixed. Therefore, it becomes applicable. As a result, even with an engine having a cylinder with a constant bore pitch, the unbalanced force can be set even at the end portion where the unbalanced moment per weight is large as described above for the CW thickness of the crankshaft. Power can be obtained efficiently.

  In the first and second embodiments and the modified examples, the thrust receiving surfaces are provided on both side surfaces of the second journal 812 in the crankcase. However, the present invention is not limited to this. That is, among the plurality of counterweights spaced apart in the axial direction, in the crankshaft in which the CW with gear is provided on one end side of the crankshaft, the thrust receiving portion is disposed on the other end side of the crankshaft. It is only necessary to support the journal and to be provided in the journal receiving portion provided in the crankcase. For example, as shown in FIG. 9, a set of one side 8111 of a journal receiving inner wall (journal receiving portion) 811 and a crankshaft surface 6311 facing this one side 8111, one side 8131 of journal receiving inner wall 813 and this one side 8131 facing each other. The thrust may be restricted by both the pair with the surface 6341 of the CW 634.

  In the crankshaft according to the present embodiment, when the crankshaft is provided on the crankcase, a pair of thrust receiving surfaces as thrust receiving portions for restricting movement of the crankshaft in the axial direction are provided on the side surfaces of different CWs. Also good. In other words, among the side surfaces of the plurality of CWs arranged on the other end side of the crankshaft, the side surface connected to the journal on one end side in the axial direction and the side surface connected to the journal on the other end side in the axial direction are: A thrust receiving surface may be provided for each.

  Such a crankshaft is schematically shown as a modification in FIGS. The crankshafts 60C, 60D, and 60E shown in FIGS. 12 to 14 are crankshafts that have a rotational couple by arranging a plurality of crankpins, and are used in a reciprocating internal combustion engine having a plurality of cylinders. It has the same basic configuration as 60B. Therefore, in these crankshafts 60C, 60D, and 60E, the same components as those of the crankshaft 60B are assigned the same names and the same reference numerals, and description thereof is omitted.

  That is, the crankshafts 60C, 60D, and 60E shown in FIGS. 12 to 14 have a plurality of CWs that are spaced apart in the axial direction. And between these CW, the said crankpin and the some journal pivotally supported by a crankcase are arrange | positioned alternately. In addition, a gear for outputting the rotational power of the engine is provided on the outer periphery of CW638B disposed on one end side in the axial direction among the plurality of CWs. In addition, in the CW arranged on the other end side, that is, in the CW arranged on the side opposite to the CW 638B across the center line, a pair of thrust receiving surfaces is provided on the side surface of the CW continuous with the journal. It has been. In FIGS. 12 to 14, the direction of the thrust direction in which the thrust receiving surface of the crankshaft is regulated when the crankshaft is rotatably attached to the crankcase is indicated by “▽”.

  In the crankshaft 60C shown in FIG. 12, in the first CW 631C arranged on the other end side, a thrust surface is provided on the side surface 6311C that is continuous with the first journal 621 on the other end side of the crankshaft 60C. In the crankshaft 60C, in the second CW 632C, a thrust surface is provided on a side surface 6321C that is continuous with the second journal 622 on one end side of the crankshaft 60C. As described above, in the crankshaft 60C, the side surfaces 6311C and 6321C form a pair of thrust surfaces. When the crankshaft 60C is attached to the crankcase, the side surface of the journal receiving inner wall facing each of the thrust surfaces Restrict movement in the axial direction.

  In the crankshaft 60D shown in FIG. 13, in the first CW 631D arranged on the other end side, a thrust surface is provided on a side surface 6311D that is continuous with the first journal 621 on the other end side of the crankshaft 60D. In the crankshaft 60D, in the fourth CW 634D, a thrust surface is provided on a side surface 6341D continuous with the third journal 623 on one end side of the crankshaft 60D. As described above, in the crankshaft 60D, the side surfaces 6311D and 6341D form a pair of thrust surfaces. When the crankshaft 60D is attached to the crankcase, the side surface of the journal receiving inner wall facing each of the thrust surfaces Restrict movement in the axial direction.

  In the crankshaft 60E shown in FIG. 14, in the third CW 633E disposed on the other end side, a thrust surface is provided on a side surface 6331E that is continuous with the second journal 622 on the other end side of the crankshaft 60E. Further, in the crankshaft 60D, in the fourth CW 634E, a thrust surface is provided on a side surface 6341E that is continuous with the third journal 623 on one end portion side of the crankshaft 60E. As described above, in the crankshaft 60E, the side surfaces 6331E and 6341E form a pair of thrust surfaces. When the crankshaft 60E is attached to the crankcase, the side surface of the inner wall of the journal receiver that faces each of the thrust surfaces. Restrict movement in the axial direction. Note that the crankshafts 60C, 60D, and 60E can achieve the same operational effects as the crankshafts 60, 60A, and 60B.

  The reciprocating internal combustion engine according to the present invention is not limited to the above embodiments, and can be implemented with various modifications.

  A reciprocating internal combustion engine, a crankshaft, a vehicle, and a motorcycle according to the present invention can efficiently generate an unbalanced moment and have an effect of suppressing the overall weight, and a motorcycle in which a mounting area is limited. It is particularly useful as applied to.

6, 6A, 6B Engine body 7, 7A, 7B Transmission 8, 8A, 8B Engine 10 Motorcycle 13 Rear wheel 14 Drive chain 60, 60A, 60B, 60C, 60D, 60E Crankshaft (Crankshaft)
68 Piston 69 Connecting rod 71 Main shaft 72, 721B Reduction gear 73 Drive shaft 74, 741B, 742B Clutch 75 Transmission gear group 76 Sprocket 90, 90A Balance shaft 91, 91A Balance gear 93 Balancer driven gear 602 External gear (separate gear)
621, 622, 623, 624, 625 Journal 631, 631C, 631D, 632, 632C, 633, 633E, 634, 634D, 634E, 635, 636, 637, 637A, 637B, 638 CW (counterweight)
639 Gear 641, 642, 643, 644 Crank pin 680, 680A, 680B Thrust receiving portion 711, 711B First main shaft 712, 712B Second main shaft 721 First reduction gear 722 Second reduction gear 741 First clutch 742 Second clutch 810, 810A, 810B Crankcase 811, 812, 813, 814, 815 Journal receiving inner wall (journal receiving part)
637, 638A, 638B CW with gear
6311C, 6311D, 6321, 6321C, 6331, 6331E, 6341D
6341E Thrust receiving surface

Claims (6)

A crankshaft having a rotational couple by arranging a plurality of crankpins;
A crankcase that rotatably supports a plurality of journals of the crankshaft;
A multi-cylinder reciprocating internal combustion engine comprising:
The crankcase has a thrust receiving portion for restricting movement in the thrust direction of the crankshaft,
The crankshaft is formed with a gear for outputting the rotational power of the engine on the outer periphery of the counterweight disposed on one end side of the crankshaft among the plurality of counterweights spaced apart in the axial direction. ,
The thrust receiving portion is provided in a journal receiving portion that supports a journal disposed on the other end side among the plurality of journals in the crankshaft, and is provided in the crankcase.
A reciprocating internal combustion engine. In the crankcase, at least three cylinders or more are arranged in the direction of the crankshaft, and are provided with equal intervals between the centers of the cylinders.
The reciprocating internal combustion engine according to claim 1. Another gear that outputs the rotational power of the engine is fixed to the other end of the crankshaft by press-fitting,
A transmission further comprising a plurality of clutches each of which receives power from the gear and the separate gear;
The reciprocating internal combustion engine according to claim 1 or 2. A crankshaft having a rotational couple by arranging a plurality of crankpins and used in a reciprocating internal combustion engine having a plurality of cylinders,
Having a plurality of counterweights spaced apart in the axial direction, the crankpins and a plurality of journals pivotally supported by the crankcase are alternately arranged between the counterweights,
Among the plurality of counterweights, a gear for outputting the rotational power of the engine is provided on the outer periphery of the counterweight disposed on the one end side in the axial direction, and the counterweight disposed on the other end side A pair of thrust receiving surfaces is provided on the side of the counterweight connected to the journal.
Crankshaft. The reciprocating internal combustion engine according to any one of claims 1 to 3,
vehicle. The reciprocating internal combustion engine according to any one of claims 1 to 3,
Motorcycle.

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