JP2014081028A - Multi-cylinder engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To restrict a vibration degradation accompanied by a lateral action of a crank shaft without changing a shape of the crank shaft in particular.SOLUTION: There is provided a flat-four engine 1 in which a first cylinder 11, second cylinder 12, third cylinder 13 and fourth cylinder 14 are arranged in this order from one end and a flywheel 15 is arranged at the other end, and this engine has a weight member 40 that is movable in a direction where a rotation center of the flywheel 15 and an axis center of a third pin 13b are projected onto a plane of the flywheel 15, the weight 40 is positioned at the rotation center side of the flywheel 15 under a state in which the flywheel 15 is not rotated, and the weight member can be moved to the outer end of the flywheel 15 at the axis center side of the third pin 13b by a centrifugal force generated under a rotation of the flywheel 15.

Description

  The present invention relates to a multi-cylinder engine such as a horizontally opposed four-cylinder engine in which vibration generated in a crankshaft or the like is improved.

  In general, in a four-cylinder engine, as shown in the schematic diagram of the horizontally opposed four-cylinder engine in FIG. 5, the first cylinder 101, the second cylinder 102, the third cylinder 103, and the fourth cylinder from one end side. A flywheel 105 is provided at the other end, which is arranged in order with the cylinder 104. In the four-cylinder engine 100, the crankshaft 110 supports the first pin 101b that rotatably supports the connecting rod 101a of the first cylinder 101 and the connecting rod 104a of the fourth cylinder 104 that is rotatably supported. The direction of the force acting on the fourth pin 104b, the second pin 102b that rotatably supports the connecting rod 102a of the second cylinder 102, and the third pin 103b that rotatably supports the connecting rod 103a of the third cylinder 103 The direction of the working force acts in the opposite direction. In the figure, reference numerals 111, 112, 113, 114, and 115 denote a first journal, a second journal, a third journal, a fourth journal, and a fifth journal that support the crankshaft 110, respectively. Thus, in the four-cylinder engine 100, because of the structure, inertial force is always input in the reverse direction to the first pin 101b, the fourth pin 104b, the second pin 102b, and the third pin 103b. The crankshaft 110 is deformed like a bow due to inertial force. Due to the bow deformation generated by this inertial force, the first journal 111, the third journal 113, and the fifth journal 115 are always located on the explosion cylinder side at the top dead center (TDC) timing of each cylinder. When a larger in-cylinder pressure input is received, the crankshaft 110 is pushed back and crossing behavior occurs (FIG. 4 shows the crossing behavior of the axis of the fifth journal 115). When crossing behavior occurs in the moderate acceleration region of medium loads and medium rotations such as city riding, the fifth journal 115 has a large vibration during the crossing behavior due to the weight of the flywheel 105 and the clutch fastened in the vicinity. Therefore, if the crossing behavior of the fifth journal 115 occurs at the explosion timing of the fourth cylinder 104, the driver may feel uncomfortable or uncomfortable due to the cranking sound using this as the excitation source. In order to improve such bending vibration of the crankshaft, for example, in Japanese Patent Application Laid-Open No. 2003-227548 (hereinafter referred to as Patent Document 1), in an in-line four-cylinder engine, cranks are provided at portions corresponding to the first and fourth cylinders. The counterweight included in the shaft is lighter than the counterweight included in the crankshaft at the portions corresponding to the second and third cylinders, and the crank pulley and the flywheel have portions corresponding to the second and third cylinders. A technique for providing an additional weight for generating an inertial force in phase with the inertial force applied to the crankshaft is disclosed.

JP 2003-227548 A

  However, in the technology of the in-line four-cylinder engine disclosed in Patent Document 1 described above, it is necessary to reshape the counterweight according to the engine characteristics, and a common crankshaft is used in various engines. There is a problem that it is difficult to adopt from the viewpoint of sharing parts, cost and design time.

  The present invention has been made in view of the above circumstances, and it is an object of the present invention to provide a multi-cylinder engine that can suppress the deterioration of vibration associated with the crossing behavior of the crankshaft without changing the shape of the crankshaft.

  A multi-cylinder engine according to an aspect of the present invention includes a first cylinder, a second cylinder, a third cylinder, and a fourth cylinder arranged in this order from one end side, and a flywheel at the other end. A first pin that rotatably supports the connecting rod of the first cylinder, a direction of a force acting on a fourth pin that rotatably supports the connecting rod of the fourth cylinder, and a connecting rod of the second cylinder; In the multi-cylinder engine provided with a crankshaft in which the direction of the force acting on the second pin that rotatably supports the third pin and the third pin that rotatably supports the connecting rod of the third cylinder is reversed, the flywheel The center of rotation of the third pin and the axis of the third pin are projected on the flywheel surface and can be moved in a connected direction, and when the flywheel is not rotating, it is positioned on the rotation center side of the flywheel. ,the above By centrifugal force flywheel occurs by rotating, provided movable weight member on the outer end side of the flywheel of the third pin axis side.

  According to the multi-cylinder engine of the present invention, it is possible to suppress the deterioration of vibration associated with the crossing behavior of the crankshaft without particularly changing the shape of the crankshaft.

1 is a schematic diagram illustrating a structure of a horizontally opposed four-cylinder engine according to an embodiment of the present invention. FIG. 2A is a cross-sectional view of a main part showing a structure of a flywheel according to an embodiment of the present invention, FIG. 2A shows a state when the flywheel is stationary, and FIG. 2B shows a state when the flywheel is rotated. . It is explanatory drawing of the effect which concerns on one Embodiment of this invention. It is explanatory drawing of the crossing behavior of the shaft center of the 5th journal by a prior art. It is a schematic diagram explaining the structure of the horizontally opposed 4-cylinder engine by a prior art.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
In FIG. 1, reference numeral 1 denotes a horizontally opposed four-cylinder engine as a multi-cylinder engine. From one end side, a first cylinder 11, a second cylinder 12, a third cylinder 13, and a fourth cylinder 14 are shown. The flywheel 15 is provided in the other end part in order.

  In the horizontally opposed four-cylinder engine 1, the crankshaft 10 has a first pin 11 b that rotatably supports the connecting rod 11 a of the first cylinder 11 and a connecting rod 14 a of the fourth cylinder 14 that is rotatably supported. The direction of the force acting on the fourth pin 14b, the second pin 12b that rotatably supports the connecting rod 12a of the second cylinder 12, and the third pin 13b that rotatably supports the connecting rod 13a of the third cylinder 13 The direction of the working force acts in the opposite direction. In FIG. 1, reference numerals 21, 22, 23, 24, and 25 denote a first journal, a second journal, a third journal, a fourth journal, and a fifth journal that support the crankshaft 10.

  Here, as shown in the front view of the flywheel 15 in FIG. 2 (front view as viewed from the fourth cylinder 14 side), the flywheel 15 according to the present embodiment has a shaft center of the third pin 13b and the fourth center. The axis of the third pin 13b and the axis of the fourth pin 14b on a straight line Lh passing through the rotation center Pc of the flywheel 15 projected onto the flywheel 15 surface. The hollow portions 31, 32, 33, and 34 having substantially rectangular parallelepiped shapes are respectively provided at four locations on the outer end side of the flywheel 15 on the straight line Lv orthogonal to the straight line Lh through the rotation center Pc of the flywheel 15. Is formed.

  Of these four cavities 31, 32, 33, 34, the cavity 31 formed on the axial center side of the third pin 13b is more of the flywheel 15 than the other three cavities 32, 33, 34. Widely formed on the rotation center Pc side.

  A weight member 40 that is movable in the direction of the straight line Lh is provided in the hollow portion 31 formed on the axial center side of the third pin 13b. The weight member 40 includes a first coil spring 41 serving as a first urging unit that constantly urges the flyhole 15 toward the rotation axis center Pc, and a second coil that constantly urges the flywheel 15 toward the outer end side. It is held by a second coil spring 42 as urging means.

  Here, the urging force of the first coil spring 41 is set to be stronger than the urging force of the second coil spring 42, and when the flywheel 15 is stationary as shown in FIG. The urging force of the first coil spring 41 overcomes the urging force of the second coil spring 42, and the weight member 40 is pulled toward the rotation center Pc side of the flywheel 15. The wheel is balanced on the rotation axis center Pc side of the wheel. On the contrary, as shown in FIG. 2B, when the flywheel 15 is rotated at a rotational speed of a predetermined value or higher, the centrifugal force generated thereby acts on the weight member 40, and the second coil spring 42 A force obtained by adding centrifugal force to the urging force overcomes the urging force of the first coil spring 41, and the weight member 40 is moved to the outer end side of the flywheel 15, so that the end of the crankshaft 10 is illustrated in the drawing. A force indicated by an arrow A is applied.

  Next, the operation of the horizontally opposed four-cylinder engine 1 configured as described above will be described. First, in a state where the horizontally opposed four-cylinder engine 1 is stopped (stationary), the crankshaft 10 is not bowed as shown in FIG. Further, in this state, the weight member 40 provided on the flywheel 15 has the urging force of the first coil spring 41 overcomes the urging force of the second coil spring 42 as shown in FIG. The center of gravity of the flywheel 15 is balanced to the rotation axis center Pc side of the flywheel 15 in a state of being drawn toward the rotation center Pc side of the flywheel 15.

  From such a state, when the horizontally opposed four-cylinder engine 1 is operated and enters a moderately accelerated state of medium load and medium rotation such as city riding, as described above, the horizontally opposed four-cylinder engine 1 is structurally first. Since the inertia force is always input in the reverse direction to the pin 11b, the fourth pin 14b, the second pin 12b, and the third pin 13b, the crankshaft 10 is deformed like a bow by the inertia force as described above. To do.

  Conventionally, due to the bow deformation generated by this inertial force, the first journal 21, the third journal 23, and the fifth journal 25 are always located on the explosion cylinder side at each cylinder top dead center (TDC) timing. When an in-cylinder pressure input larger than the inertia force is received, the crankshaft 10 is pushed back, and a crossing behavior occurs. In particular, since the fifth journal 25 has a large vibration during the crossing behavior due to the weight of the flywheel 15 and the clutch fastened in the vicinity, the crossing behavior of the fifth journal 25 occurs at the explosion timing of the fourth cylinder 14. Then, there is a possibility that the driver may feel uncomfortable or uncomfortable due to a cranking sound using this as a vibration source.

  However, in the present embodiment, as shown in FIG. 2 (b), when the flywheel 15 is rotated at a rotational speed equal to or higher than a predetermined value, the centrifugal force generated thereby acts on the weight member 40, so that the second The force obtained by adding centrifugal force to the urging force of the coil spring 42 overcomes the urging force of the first coil spring 41, and the weight member 40 connects the rotational center of the flywheel 15 and the axis of the third pin 13 b to the flywheel. 2 is moved to the outer end side of the flywheel 15 along the straight line Lh projected and connected onto the 15th surface, and is shown by the arrow A in FIG. 2B and FIG. Applying force. The force acting on the end of the crankshaft 10 on the flywheel 15 side suppresses the inclination of the end of the crankshaft 10 on the flywheel 15 side in the direction of the fourth pin 14b (α2 in FIG. 3 <FIG. 5). Α1). As a result, the crossing behavior of the fifth journal 25 can be suppressed at the timing of the explosion of the fourth cylinder 14 as has occurred in the prior art. It is possible to prevent the user from feeling uncomfortable.

  Thus, according to the embodiment of the present invention, the first cylinder 11, the second cylinder 12, the third cylinder 13, and the fourth cylinder 14 are arranged in this order from one end side, and the other In the horizontally opposed four-cylinder engine 1 provided with a flywheel 15 at the end, the center of rotation of the flywheel 15 and the axis of the third pin 13b are projected on the flywheel 15 surface and freely movable in a connected direction. When the flywheel 15 is not rotating, the weight member 40 is located on the rotation center side of the flywheel 15 and is movable to the outer end side of the flywheel 15 by the centrifugal force generated by the rotation of the flywheel 15. Provided. For this reason, without changing the shape of the crankshaft in particular, it is possible to suppress the deterioration of vibration caused by the crossing behavior of the crankshaft by using a common crankshaft in various engines. It is possible to prevent the driver from feeling uncomfortable or uncomfortable due to the hitting sound.

  In the embodiment of the present invention, the example in which the present invention is applied to the horizontally opposed four-cylinder engine 1 as a multi-cylinder engine has been described. However, it goes without saying that the present invention can also be applied to an in-line four-cylinder engine.

DESCRIPTION OF SYMBOLS 1 Horizontally opposed 4 cylinder engine 10 Crankshaft 11 1st cylinder 11a Connecting rod 11b 1st pin 12 2nd cylinder 12a Connecting rod 12b 2nd pin 13 3rd cylinder 13a Connecting rod 13b 3rd pin 14 4th cylinder 14a connecting rod 14b fourth pin 15 flywheel 21 first journal 22 second journal 23 third journal 24 fourth journal 25 fifth journal 31 cavity part 32 cavity part 33 cavity part 34 cavity part 40 weight member 41 first coil Spring (first biasing means)
42 2nd coil spring (2nd biasing means)

Claims (4)

The first cylinder, the second cylinder, the third cylinder, and the fourth cylinder are arranged in this order from one end side, and a flywheel is provided at the other end, and the connecting rod of the first cylinder is Direction of force acting on the first pin for rotatably supporting the connecting rod of the fourth cylinder and the fourth pin for rotatably supporting the connecting rod of the fourth cylinder, the second pin for rotatably supporting the connecting rod of the second cylinder, and the above In a multi-cylinder engine provided with a crankshaft in which the direction of the force acting on the third pin that rotatably supports the connecting rod of the third cylinder is opposite to that,
The flywheel can be moved in a direction in which the center of rotation of the flywheel and the axis of the third pin are projected onto the flywheel surface, and when the flywheel is not rotating, the flywheel is on the rotation center side. A multi-cylinder engine provided with a movable weight member on the outer end side of the flywheel on the third pin shaft core side by centrifugal force generated by rotation of the flywheel .   On the straight line passing through the center of rotation of the flywheel obtained by projecting the axis of the third pin and the axis of the fourth pin onto the flywheel surface, the axis of the third pin and the axis Cavities are formed on the axis side of the fourth pin and on the outer end side of the flywheel on a straight line passing through the rotation center of the flywheel and orthogonal to the straight line, and the axis of the third pin The multi-cylinder engine according to claim 1, wherein the weight member is housed in a hollow portion provided on the core side.   The weight member housed in the cavity has a first urging means that constantly urges toward the rotation shaft center side of the flyhole, and a second urging means that always urges to the outer end side of the flywheel. The multi-cylinder engine according to claim 2, wherein the urging force of the first urging means is set stronger than the urging force of the second urging means.   The multi-cylinder engine according to any one of claims 1 to 3, wherein the multi-cylinder engine is configured as a horizontally opposed four-cylinder type.

Images