Crankshaft

Abstract

To suppress vibration.SOLUTION: A crankshaft includes a plurality of journal parts supported by respective bearings, and an opposing surface opposing to a thrust surface of the bearing supporting at least one of the plurality of journal parts. The opposing surface is inclined with respect to a radial direction of the at least one journal part.SELECTED DRAWING: Figure 4

Description

[Technical field]

[0001] The present invention relates to a crankshaft. [Background technology]

[0002] A vehicle equipped with an engine is provided with a crankshaft for transmitting power generated by the engine. The crankshaft has a number of journals, each of which is supported by a bearing. As described in Patent Document 1, various techniques have been proposed for the structure of the portion where the journals come into contact with the bearings. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2009-264465 A Summary of the Invention [Problem to be solved by the invention]

[0004] However, the crankshaft rotates in a state of elastic deformation due to centrifugal force. This causes local contact between the crankshaft and the bearings, resulting in vibration. Such vibration can cause noise and other issues, so it is desirable to suppress the vibration.

[0005] SUMMARY OF THE PRESENT EMBODIMENTS Accordingly, an object of the present invention is to provide a crankshaft capable of suppressing vibration. [Means for solving the problem]

[0006] In order to solve the above problems, a crankshaft according to one embodiment of the present invention comprises: A plurality of journal portions each supported by a bearing; an opposing surface opposing a thrust surface of the bearing supporting at least one of the plurality of journal portions; Equipped with The opposing surface is inclined with respect to a radial direction of the at least one journal portion. Effect of the Invention

[0007] According to the present invention, it is possible to suppress vibration. [Brief description of the drawings]

[0008] [Figure 1] FIG. 1 is a schematic diagram showing a schematic configuration of a vehicle according to an embodiment of the present invention. [Diagram 2] FIG. 2 is a schematic diagram showing elastic deformation during rotation of a crankshaft according to an embodiment of the present invention. [Diagram 3] FIG. 3 is a schematic diagram showing elastic deformation during rotation of the crankshaft according to the embodiment of the present invention. [Figure 4] FIG. 4 is an enlarged view showing an area enclosed by a dashed line in FIG. 1 when the crankshaft is stopped. [Diagram 5] FIG. 5 is an enlarged view showing an area enclosed by a dashed dotted line in FIG. 1 during rotation of the crankshaft. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] Hereinafter, an embodiment of the present invention will be described in detail with reference to the accompanying drawings. The specific dimensions, materials, numerical values, etc. shown in the embodiment are merely examples for facilitating understanding of the invention, and do not limit the present invention unless otherwise specified. In this specification and drawings, elements having substantially the same functions and configurations are given the same reference numerals to avoid repeated explanations, and elements not directly related to the present invention are not shown.

[0010] <Vehicle configuration> The configuration of a vehicle 1 according to an embodiment of the present invention will be described with reference to FIG.

[0011] Fig. 1 is a schematic diagram showing a general configuration of a vehicle 1. The vehicle 1 is equipped with an engine such as a gasoline engine, which is a spark ignition type internal combustion engine. As shown in Fig. 1, the vehicle 1 is equipped with a plurality of cylinders 2, a plurality of pistons 3 provided for each cylinder 2, a plurality of connecting rods 4 provided for each cylinder 2, a crankshaft 5, a flywheel 6, and a bearing structure 7.

[0012] In Fig. 1, the vehicle front direction, vehicle rear direction, vehicle right direction, and vehicle left direction are respectively indicated as front, rear, right, and left. Note that, hereinafter, the vehicle front direction, vehicle rear direction, vehicle right direction, and vehicle left direction will also be simply referred to as the front direction, rear direction, right direction, and left direction, respectively.

[0013] The following mainly describes the example of Fig. 1 in which the vehicle 1 is equipped with a horizontally opposed engine. However, as described later, the configuration of the vehicle 1 is not limited to the example of Fig. 1. For example, the number and arrangement of the cylinders 2 are not limited to the example of Fig. 1.

[0014] The vehicle 1 is provided with four cylinders 2: a first cylinder 2-1, a second cylinder 2-2, a third cylinder 2-3, and a fourth cylinder 2-4. The first cylinder 2-1, the second cylinder 2-2, the third cylinder 2-3, and the fourth cylinder 2-4 are arranged in this order from front to back in the front-to-rear direction. The first cylinder 2-1 and the third cylinder 2-3 are arranged to the right of the crankshaft 5. The second cylinder 2-2 and the fourth cylinder 2-4 are arranged to the left of the crankshaft 5.

[0015] A piston 3 is slidably provided inside each cylinder 2, and a combustion chamber is formed by the piston 3. Specifically, a first piston 3-1, a second piston 3-2, a third piston 3-3, and a fourth piston 3-4 are provided in the first cylinder 2-1, the second cylinder 2-2, the third cylinder 2-3, and the fourth cylinder 2-4, respectively. A connecting rod 4 is connected to each piston 3. Specifically, a first connecting rod 4-1, a second connecting rod 4-2, a third connecting rod 4-3, and a fourth connecting rod 4-4 are connected to the first piston 3-1, the second piston 3-2, the third piston 3-3, and the fourth piston 3-4, respectively. Each connecting rod 4 is connected to a crankshaft 5.

[0016] For example, a fuel injection valve and a spark plug are provided facing the combustion chamber in each cylinder 2. A mixture containing air and fuel is formed in the combustion chamber by the fuel injected by the fuel injection valve, and the mixture is burned by ignition of the spark plug. This causes a piston 3 to perform a linear reciprocating motion, and power is transmitted to a crankshaft 5 via a connecting rod 4.

[0017] In the vehicle 1, ignition is performed in the order of the first cylinder 2-1, the third cylinder 2-3, the second cylinder 2-2, and the fourth cylinder 2-4. Therefore, when the first piston 3-1 of the first cylinder 2-1 is located at the bottom dead center as shown in FIG. 1, the second piston 3-2 of the second cylinder 2-2 is located at the bottom dead center, and the third piston 3-3 of the third cylinder 2-3 and the fourth piston 3-4 of the fourth cylinder 2-4 are located at the top dead center. On the other hand, when the first piston 3-1 of the first cylinder 2-1 is located at the top dead center, the second piston 3-2 of the second cylinder 2-2 is located at the top dead center, and the third piston 3-3 of the third cylinder 2-3 and the fourth piston 3-4 of the fourth cylinder 2-4 are located at the bottom dead center.

[0018] The crankshaft 5 extends in the front-rear direction. The crankshaft 5 rotates about a rotation axis extending along the front-rear direction. A crank pulley (not shown) is provided at the front end of the crankshaft 5. A flywheel 6 is provided at the rear end of the crankshaft 5. The rear end of the crankshaft 5 is connected to a transmission (not shown) via the flywheel 6. The flywheel 6 accumulates the rotational energy transmitted to the crankshaft 5 and stabilizes the rotation of the crankshaft 5 by inertia force.

[0019] The crankshaft 5 includes a plurality of journal portions 51, a plurality of crank pins 52, and a plurality of counterweights 53. As described later, the crankshaft 5 rotates in a state in which it is elastically deformed by centrifugal force. Fig. 1 shows the crankshaft 5 in a stopped state.

[0020] Each journal portion 51 has a cylindrical shape. When the crankshaft 5 is stopped, the central axis of each journal portion 51 is coaxial with the rotation axis of the crankshaft 5. The crankshaft 5 is provided with five journal portions 51, namely, a first journal portion 51-1, a second journal portion 51-2, a third journal portion 51-3, a fourth journal portion 51-4, and a fifth journal portion 51-5. The first journal portion 51-1, the second journal portion 51-2, the third journal portion 51-3, the fourth journal portion 51-4, and the fifth journal portion 51-5 are arranged in this order from front to back in the front-rear direction. As described later, each journal portion 51 is rotatably supported by a bearing 71 of the bearing structure 7.

[0021] Each crankpin 52 has a cylindrical shape. When the crankshaft 5 is stopped, the central axis of the crankpin 52 is eccentric with respect to the rotation axis of the crankshaft 5. The crankshaft 5 is provided with four crankpins 52, namely, a first crankpin 52-1, a second crankpin 52-2, a third crankpin 52-3, and a fourth crankpin 52-4. The first crankpin 52-1, the second crankpin 52-2, the third crankpin 52-3, and the fourth crankpin 52-4 are arranged from front to back in this order in the front-to-rear direction. Each crankpin 52 is inserted into an end of the connecting rod 4 and connected to the connecting rod 4. Specifically, the first crank pin 52-1, the second crank pin 52-2, the third crank pin 52-3 and the fourth crank pin 52-4 are connected to the first connecting rod 4-1, the second connecting rod 4-2, the third connecting rod 4-3 and the fourth connecting rod 4-4, respectively.

[0022] The journal portions 51 and the crank pins 52 are arranged alternately in the front-rear direction. Specifically, the first crank pin 52-1 is provided between the first journal portion 51-1 and the second journal portion 51-2, and connects the first journal portion 51-1 and the second journal portion 51-2. The second crank pin 52-2 is provided between the second journal portion 51-2 and the third journal portion 51-3, and connects the second journal portion 51-2 and the third journal portion 51-3. The third crank pin 52-3 is provided between the third journal portion 51-3 and the fourth journal portion 51-4, and connects the third journal portion 51-3 and the fourth journal portion 51-4. The fourth crank pin 52-4 is provided between the fourth journal portion 51-4 and the fifth journal portion 51-5, and connects the fourth journal portion 51-4 and the fifth journal portion 51-5.

[0023] In the circumferential direction of the crankshaft 5, the position of the first crankpin 52-1 and the position of the fourth crankpin 52-4 are aligned with each other. In addition, in the circumferential direction of the crankshaft 5, the position of the second crankpin 52-2 and the position of the third crankpin 52-3 are aligned with each other, and are shifted by 180° from the positions of the first crankpin 52-1 and the fourth crankpin 52-4. In this way, in the circumferential direction of the crankshaft 5, the positions of the first crankpin 52-1 and the fourth crankpin 52-4 are shifted by 180° from the positions of the second crankpin 52-2 and the third crankpin 52-3. For example, as shown in FIG. 1, when the first crankpin 52-1 and the fourth crankpin 52-4 are positioned to the left of the crankshaft 5, the second crankpin 52-2 and the third crankpin 52-3 are positioned to the right of the crankshaft 5.

[0024] The counterweight 53 is provided on the journal portion 51 on the side of the adjacent crank pin 52, and protrudes in the opposite direction to the direction of the crank pin 52 relative to the journal portion 51. The counterweight 53 is a weight for balancing the crank pin 52 when the crankshaft 5 rotates. Eight counterweights 53 are provided on the crankshaft 5: a first counterweight 53-1, a second counterweight 53-2, a third counterweight 53-3, a fourth counterweight 53-4, a fifth counterweight 53-5, a sixth counterweight 53-6, a seventh counterweight 53-7, and an eighth counterweight 53-8. The first counterweight 53-1, the second counterweight 53-2, the third counterweight 53-3, the fourth counterweight 53-4, the fifth counterweight 53-5, the sixth counterweight 53-6, the seventh counterweight 53-7, and the eighth counterweight 53-8 are arranged in this order from the front to the back in the front-rear direction.

[0025] The first counterweight 53-1 is provided at the rear end of the first journal portion 51-1. The second counterweight 53-2 is provided at the front end of the second journal portion 51-2. The third counterweight 53-3 is provided at the rear end of the second journal portion 51-2. The fourth counterweight 53-4 is provided at the front end of the third journal portion 51-3. The fifth counterweight 53-5 is provided at the rear end of the third journal portion 51-3. The sixth counterweight 53-6 is provided at the front end of the fourth journal portion 51-4. The seventh counterweight 53-7 is provided at the rear end of the fourth journal portion 51-4. The eighth counterweight 53-8 is provided at the front end of the fifth journal portion 51-5.

[0026] The bearing structure 7 is a structure for supporting the crankshaft 5. The bearing structure 7 includes a plurality of bearings 71. Each bearing 71 is provided in a crankcase (not shown). Each bearing 71 rotatably supports each journal portion 51 of the crankshaft 5. Specifically, each bearing 71 is a sliding bearing that supports the journal portion 51 at least in the radial direction. Each bearing 71 is arranged coaxially with one another. The central axis of the bearing 71 and the rotation axis of the crankshaft are coaxial.

[0027] The bearing structure 7 is provided with five bearings 71, namely, a first bearing 71-1, a second bearing 71-2, a third bearing 71-3, a fourth bearing 71-4, and a fifth bearing 71-5. The first bearing 71-1, the second bearing 71-2, the third bearing 71-3, the fourth bearing 71-4, and the fifth bearing 71-5 are arranged in this order from front to back in the front-rear direction. The first bearing 71-1, the second bearing 71-2, the third bearing 71-3, the fourth bearing 71-4, and the fifth bearing 71-5 support the first journal portion 51-1, the second journal portion 51-2, the third journal portion 51-3, the fourth journal portion 51-4, and the fifth journal portion 51-5, respectively.

[0028] 1, the first bearing 71-1, the second bearing 71-2, the third bearing 71-3, and the fourth bearing 71-4 have radial surfaces and radially support the journal portion 51. On the other hand, the fifth bearing 71-5 has a thrust surface in addition to the radial surface, and radially supports the journal portion 51 and axially supports the crankshaft 5.

[0029] <Operation of crankshaft and bearing structure> The operation of the crankshaft 5 and the bearing structure 7 according to the embodiment of the present invention will be described with reference to FIGS.

[0030] As described above, the crankshaft 5 rotates in a state in which it is elastically deformed by centrifugal force. Hereinafter, the elastic deformation of the crankshaft 5 during rotation will be described with reference to Figs. 2 and 3.

[0031] 2 and 3 are schematic diagrams showing elastic deformation of the crankshaft 5 during rotation. Specifically, FIG. 2 shows the crankshaft 5 in the case where the first piston 3-1 and the second piston 3-2 are located at the bottom dead center, and the third piston 3-3 and the fourth piston 3-4 are located at the top dead center, as in FIG. 1. Meanwhile, FIG. 3 shows the crankshaft 5 in the case where the first piston 3-1 and the second piston 3-2 are located at the top dead center, and the third piston 3-3 and the fourth piston 3-4 are located at the bottom dead center. Note that FIGS. 2 and 3 show the rotation axis AR of the crankshaft 5.

[0032] When the crankshaft 5 rotates, the journal portion 51 is pulled by centrifugal force in a direction toward the crank pin 52 adjacent to the journal portion 51. Specifically, the first journal portion 51-1 is pulled by centrifugal force in a direction toward the first crank pin 52-1. The second journal portion 51-2 is not easily pulled in either direction by centrifugal force because the direction toward the first crank pin 52-1 is opposite to the direction toward the second crank pin 52-2. The third journal portion 51-3 is pulled by centrifugal force in a direction toward the second crank pin 52-2 and the third crank pin 52-3. The fourth journal portion 51-4 is not easily pulled in either direction by centrifugal force because the direction toward the third crank pin 52-3 is opposite to the direction toward the fourth crank pin 52-4. The fifth journal portion 51-5 is pulled by centrifugal force in a direction toward the fourth crank pin 52-4.

[0033] Therefore, as shown in Figures 2 and 3, the crankshaft 5 rotates in a bow-like elastically deformed state. For example, in the state of Figure 2 where the third piston 3-3 of the third cylinder 2-3 is located at top dead center, if an explosion occurs in the third cylinder 2-3, the third piston 3-3 moves to bottom dead center, resulting in the state of Figure 3. Next, in the state of Figure 3, if an explosion occurs in the second cylinder 2-2, the second piston 3-2 moves to bottom dead center, resulting in the state of Figure 2. Next, in the state of Figure 2, if an explosion occurs in the fourth cylinder 2-4, the fourth piston 3-4 moves to bottom dead center, resulting in the state of Figure 3.

[0034] As described above, the flywheel 6 is provided at the rear end of the crankshaft 5. Furthermore, the rear end of the crankshaft 5 is connected to a transmission (not shown) via the flywheel 6. In this way, a heavier member is present near the rear portion of the crankshaft 5 compared to the front portion of the crankshaft 5. As a result, centrifugal force acts largely on the rear portion of the crankshaft 5. Therefore, when the crankshaft 5 rotates, a large deformation occurs mainly in the rear portion of the crankshaft 5. Specifically, the main deformation occurs in which the third journal portion 51-3 and the fifth journal portion 51-5 are pulled in opposite directions starting from the fourth journal portion 51-4.

[0035] As described above, the crankshaft 5 rotates in a state in which it is elastically deformed by centrifugal force. This causes local contact between the crankshaft 5 and the bearing 71, which generates vibrations. In this embodiment, by implementing some improvements on the crankshaft 5, it is possible to suppress vibrations caused by the crankshaft 5 rotating in a state in which it is elastically deformed by centrifugal force. Such improvements will be described below with reference to Figs. 4 and 5.

[0036] Fig. 4 is an enlarged view showing an area R enclosed by a dashed line in Fig. 1 when the crankshaft 5 is stopped. As shown in Fig. 4, the fifth bearing 71-5 has a radial surface 71-5a and thrust surfaces 71-5b and 71-5c.

[0037] The radial surface 71-5a extends in the axial direction of the fifth bearing 71-5 and has a cylindrical shape. The radial surface 71-5a is disposed coaxially with the fifth bearing 71-5. The radial surface 71-5a faces the outer peripheral surface of the fifth journal portion 51-5. The fifth bearing 71-5 supports the fifth bearing 71-5 in the radial direction via the radial surface 71-5a.

[0038] The thrust surface 71-5b and the thrust surface 71-5c extend in the radial direction of the fifth bearing 71-5 and have an annular shape. The thrust surface 71-5b and the thrust surface 71-5c are arranged coaxially with the fifth bearing 71-5. The thrust surface 71-5b extends radially outward from the front end of the radial surface 71-5a. The thrust surface 71-5c extends radially outward from the rear end of the radial surface 71-5a. The fifth bearing 71-5 supports the crankshaft 5 in the axial direction via the thrust surface 71-5b and the thrust surface 71-5c.

[0039] The crankshaft 5 has opposing surfaces F1 and F2 that face the thrust surfaces 71-5b and 71-5c of the fifth bearing 71-5. The opposing surface F1 faces the thrust surface 71-5b. The opposing surface F2 faces the thrust surface 71-5c. The fifth bearing 71-5 receives an axial load from the crankshaft 5 when the thrust surface 71-5b and the opposing surface F1 are in contact with each other, or when the thrust surface 71-5c and the opposing surface F2 are in contact with each other.

[0040] The opposing surface F1 is a portion of the surface of the crankshaft 5 that faces the thrust surface 71-5b. Specifically, the opposing surface F1 is formed by a part of the right end surface of the eighth counterweight 53-8 and a part of the right end surface of the fourth crankpin 52-4. The opposing surface F1 has an annular shape.

[0041] The opposing surface F2 is a portion of the surface of the crankshaft 5 that faces the thrust surface 71-5c. Specifically, the opposing surface F2 is a left end surface of the expanded diameter portion 54 that is connected to the rear portion of the fifth journal portion 51-5 and expands radially outward. The expanded diameter portion 54 has a cylindrical shape and is disposed coaxially with the fifth journal portion 51-5. The opposing surface F2 has an annular shape.

[0042] In the example of Fig. 4, the opposing surfaces F1 and F2 are parallel to each other. However, the opposing surfaces F1 and F2 do not have to be parallel to each other.

[0043] As shown in FIG. 4, in the crankshaft 5 according to this embodiment, the opposing surfaces F1 and F2 are inclined with respect to the radial direction of the fifth journal portion 51-5. That is, the central axis CA1 of the opposing surfaces F1 and F2 is not coaxial with the central axis CA2 of the fifth journal portion 51-5, but is inclined with respect to the central axis CA2 of the fifth journal portion 51-5. Therefore, when the crankshaft 5 is stopped, the opposing surfaces F1 and F2 are inclined with respect to the thrust surfaces 71-5b and 71-5c of the fifth bearing 71-5. For example, when the crankshaft 5 is stopped as shown in FIG. 4, the central axis CA2 of the fifth journal portion 51-5 is coaxial with the rotation axis AR of the crankshaft 5, but the central axis CA1 of the opposing surfaces F1 and F2 is inclined with respect to the rotation axis AR of the crankshaft 5.

[0044] Specifically, the opposing surfaces F1, F2 are inclined so as to move away from the fifth journal portion 51-5 in the axial direction relative to the fourth crankpin 52-4 as they approach the fourth crankpin 52-4 in the radial direction of the fifth journal portion 51-5. In other words, the central axis CA1 of the opposing surfaces F1, F2 is inclined toward the fourth crankpin 52-4 as it advances forward. For example, in the example of FIG. 4, the fourth crankpin 52-4 is located to the left of the fifth journal portion 51-5. In this example, the opposing surfaces F1, F2 are inclined rearward as they advance leftward.

[0045] FIG. 5 is an enlarged view showing an area R of the dashed line in FIG. 1 during rotation of the crankshaft 5. As described above, during rotation of the crankshaft 5, the fifth journal portion 51-5 is pulled by centrifugal force in a direction toward the fourth crankpin 52-4. For example, in the example of FIG. 4, the fifth journal portion 51-5 is pulled by centrifugal force in a leftward direction. As a result of the crankshaft 5 being elastically deformed in a bow shape as described above, the right end of the eighth counterweight 53-8 is positioned rearward of the right end of the fourth crankpin 52-4. For example, as shown in FIG. 5, when viewed from above in a state in which the fourth crankpin 52-4 is positioned to the left of the fifth journal portion 51-5, the crankshaft 5 is deformed so that the fourth crankpin 52-4, the eighth counterweight 53-8, and the fifth journal portion 51-5 rotate in a clockwise direction.

[0046] When the crankshaft 5 rotates as shown in Fig. 5, the center axis CA2 of the fifth journal portion 51-5 is inclined with respect to the rotation axis AR of the crankshaft 5. Specifically, the center axis CA2 of the fifth journal portion 51-5 is inclined toward the side opposite to the fourth crankpin 52-4 as it advances forward. As a result, the center axis CA1 of the opposing surfaces F1, F2 becomes coaxial with the rotation axis AR of the crankshaft 5. Therefore, as shown in Fig. 5, when the crankshaft 5 rotates, the opposing surfaces F1, F2 become parallel to the thrust surfaces 71-5b, 71-5c of the fifth bearing 71-5.

[0047] Here, for example, if the opposing surfaces F1 and F2 are not inclined with respect to the radial direction of the fifth journal portion 51-5, when the crankshaft 5 is stopped, the opposing surfaces F1 and F2 are parallel to the thrust surfaces 71-5b and 71-5c of the fifth bearing 71-5. However, when the crankshaft 5 rotates, the opposing surfaces F1 and F2 are inclined with respect to the thrust surfaces 71-5b and 71-5c of the fifth bearing 71-5 due to elastic deformation of the crankshaft 5. Therefore, the opposing surfaces F1 and F2 and the thrust surfaces 71-5b and 71-5c are in local contact with each other rather than in surface contact with each other. This causes large vibrations.

[0048] On the other hand, in this embodiment, as described above, the opposing surfaces F1 and F2 are inclined with respect to the radial direction of the fifth journal portion 51-5. This can prevent the opposing surfaces F1 and F2 from inclining with respect to the thrust surfaces 71-5b and 71-5c of the fifth bearing 71-5 during rotation of the crankshaft 5, so that the opposing surfaces F1 and F2 can be in surface contact with the thrust surfaces 71-5b and 71-5c, and local contact between the opposing surfaces F1 and F2 and the thrust surfaces 71-5b and 71-5c can be prevented. Therefore, vibration can be prevented. Furthermore, friction can be reduced by preventing local contact between the opposing surfaces F1 and F2 and the thrust surfaces 71-5b and 71-5c.

[0049] As described above, centrifugal force acts largely on the rear portion of the crankshaft 5. Therefore, local contact between the crankshaft 5 and the fifth bearing 71-5 in the vicinity of the fifth journal portion 51-5 has a large effect on the occurrence of vibration. Therefore, vibration can be effectively suppressed by suppressing local contact between the crankshaft 5 and the fifth bearing 71-5 in the vicinity of the fifth journal portion 51-5.

[0050] An example of the vehicle 1 has been described above with reference to Figures 1 to 5. However, as long as the opposing surface facing the thrust surface of the bearing 71 supporting at least one of the plurality of journal portions 51 is inclined with respect to the radial direction of the at least one journal portion 51, the configuration of the vehicle 1 may be modified in various ways from the above example.

[0051] For example, in the above, an example has been described in which the vehicle 1 is equipped with a horizontally opposed engine having four cylinders 2. However, the configuration of the engine of the vehicle 1 is not limited to the above example. For example, the engine of the vehicle 1 does not have to be of the horizontally opposed type. In other words, the arrangement of the cylinders 2 is not limited to the above example. Also, for example, the number of cylinders 2 may be other than four.

[0052] Also, for example, in the above description, the opposing surfaces F1 and F2 are parallel to the thrust surfaces 71-5b and 71-5c of the fifth bearing 71-5 when the crankshaft 5 rotates. However, from the viewpoint of suppressing local contact between the opposing surfaces F1 and F2 and the thrust surfaces 71-5b and 71-5c, it is sufficient that the opposing surfaces F1 and F2 and the thrust surfaces 71-5b and 71-5c are closer to being parallel to each other when the crankshaft 5 rotates than when the crankshaft 5 is stopped. In other words, the opposing surfaces F1 and F2 do not need to be strictly parallel to the thrust surfaces 71-5b and 71-5c of the fifth bearing 71-5 when the crankshaft 5 rotates.

[0053] <Effect of crankshaft> The effects of the crankshaft 5 according to the embodiment of the present invention will be described.

[0054] The crankshaft 5 according to this embodiment includes a plurality of journal parts 51 each supported by a bearing 71, and opposing surfaces F1 and F2 opposed to thrust surfaces 71-5b and 71-5c of the bearing 71 supporting at least one of the plurality of journal parts 51, and the opposing surfaces F1 and F2 are inclined with respect to the radial direction of the at least one journal part 51. As a result, the opposing surfaces F1 and F2 can be prevented from inclining with respect to the thrust surfaces 71-5b and 71-5c during rotation of the crankshaft 5, so that the opposing surfaces F1 and F2 can be brought into surface contact with the thrust surfaces 71-5b and 71-5c, and local contact between the opposing surfaces F1 and F2 and the thrust surfaces 71-5b and 71-5c can be prevented. Therefore, vibration can be prevented. Furthermore, friction can be reduced by preventing local contact between the opposing surfaces F1 and F2 and the thrust surfaces 71-5b and 71-5c. In the above example, the fifth journal unit 51-5 corresponds to at least one of the journal units 51 described above.

[0055] In the crankshaft 5 according to this embodiment, the opposing surfaces F1 and F2 are preferably inclined so that as they approach the crank pin 52 connected to the at least one journal portion 51 in the radial direction, they move away from the at least one journal portion 51 in the axial direction relative to the crank pin 52. This appropriately suppresses the opposing surfaces F1 and F2 from inclining relative to the thrust surfaces 71-5b and 71-5c during rotation of the crankshaft 5. Therefore, it is appropriately realized that the opposing surfaces F1 and F2 and the thrust surfaces 71-5b and 71-5c are brought into surface contact with each other, and it is appropriately realized that local contact between the opposing surfaces F1 and F2 and the thrust surfaces 71-5b and 71-5c is suppressed. In the above example, the fifth journal portion 51-5 corresponds to the at least one journal portion 51, and the fourth crank pin 52-4 corresponds to the crank pin 52.

[0056] Furthermore, in the crankshaft 5 according to this embodiment, it is preferable that the opposing surfaces F1, F2 and the thrust surfaces 71-5b, 71-5c are closer to parallel when the crankshaft 5 is rotating than when the crankshaft 5 is stopped. This appropriately achieves surface contact between the opposing surfaces F1, F2 and the thrust surfaces 71-5b, 71-5c when the crankshaft 5 is rotating, thereby appropriately suppressing local contact between the opposing surfaces F1, F2 and the thrust surfaces 71-5b, 71-5c.

[0057] In the crankshaft 5 according to this embodiment, at least one journal portion 51 is preferably located at the rearmost position among the plurality of journal portions 51. This makes it possible to suppress local contact between the crankshaft 5 and the fifth bearing 71-5 in the vicinity of the rearmost journal portion 51, which has a large effect on the generation of vibration. Therefore, vibration can be effectively suppressed.

[0058] The above describes a preferred embodiment of the present invention with reference to the attached drawings. However, it goes without saying that the present invention is not limited to the above-described embodiment, and various modified or altered examples within the scope of the claims also fall within the technical scope of the present invention. [Explanation of symbols]

[0059] 1 vehicle 2-cylinder 2-1 No. 1 cylinder 2-2 No. 2 cylinder 2-3 3rd cylinder 2-4 4th cylinder 3 Piston 3-1 First piston 3-2 Second piston 3-3 3rd piston 3-4 4th piston 4 Connecting rod 4-1 First connecting rod 4-2 Second connecting rod 4-3 Third connecting rod 4-4 4th connecting rod 5 Crankshaft 6 Flywheel 7 Bearing structure 51 Journal Section 51-1 First Journal Section 51-2 2nd Journal Section 51-3 3rd Journal Section 51-4 4th Journal Section 51-5 5th Journal Section 52 Crank pin 52-1 No. 1 crank pin 52-2 No. 2 crank pin 52-3 3rd crank pin 52-4 4th crank pin 53 Counterweight 53-1 First counterweight 53-2 Second counterweight 53-3 3rd counterweight 53-4 4th counterweight 53-5 5th counterweight 53-6 6th counterweight 53-7 7th Counterweight 53-8 8th Counterweight 54 Expanded diameter part 71 Bearings 71-1 First bearing 71-2 No. 2 bearing 71-3 3rd bearing 71-4 4th bearing 71-5 5th bearing 71-5a Radial surface 71-5b Thrust surface 71-5c Thrust surface AR Rotation Axis CA1 center axis CA2 center axis F1 Counterface F2 Counter surface R region

Claims

1. A plurality of journal portions each supported by a bearing; an opposing surface opposing a thrust surface of the bearing supporting at least one of the plurality of journal portions; Equipped with The opposing surface is inclined with respect to a radial direction of the at least one journal portion. Crankshaft.

2. the opposing surface is inclined so as to move away from the crank pin in an axial direction of the at least one journal portion as the opposing surface approaches the crank pin in the radial direction, the at least one journal portion being connected to the crank pin; 2. The crankshaft of claim 1.

3. When the crankshaft is rotating, the opposing surface and the thrust surface are closer to being parallel to each other than when the crankshaft is stopped.

2. The crankshaft of claim 1.

4. the at least one journal portion is located at the rearmost position among the plurality of journal portions; A crankshaft according to any one of claims 1 to 3.

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