Internal combustion engine

Abstract

To reduce friction loss in an internal combustion engine.SOLUTION: An internal combustion engine 1 includes a crank shaft 20 which rotates in combination with reciprocating-motion of pistons 14a-14d within cylinders 12a-12d, bearings 40 supporting the crank shaft 20 with inner peripheral surfaces thereof, and a housing 50 in contact with outer peripheral surfaces of the bearings 40. The housing 50 has a groove 55 in each of portions thereof facing to axial opposite ends of outer peripheral surfaces of the bearings 40.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to an internal combustion engine. [Background technology]

[0002] In an internal combustion engine, a crankshaft is provided as a rotating member that rotates in conjunction with the reciprocating motion of the pistons and converts the reciprocating motion of the pistons into rotational motion. The crankshaft rotates with its shaft portion, the crank journal, supported by bearings. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2017-207167 A Summary of the Invention [Problem to be solved by the invention]

[0004] Incidentally, when an external force is applied to the crankshaft, which is a rotating member, causing the crankshaft to rotate at an angle, the crankshaft will come into contact with the end of the inner circumferential surface of the bearing, increasing the sliding contact resistance and therefore the friction loss.

[0005] The present invention has been made in consideration of these points, and has an object to reduce friction loss in an internal combustion engine. [Means for solving the problem]

[0006] One aspect of the present invention provides an internal combustion engine comprising a rotating member that rotates in conjunction with the reciprocating motion of a piston in a cylinder, a bearing that supports the rotating member on its inner circumferential surface, and a housing in contact with the outer circumferential surface of the bearing, the housing having a groove portion in a portion facing both axial ends of the outer circumferential surface of the bearing.

[0007] The groove may be formed around one circumference of the bearing in the circumferential direction.

[0008] The housing may have a contact surface in contact with an axial center portion of an outer circumferential surface of the bearing, and the groove may be recessed from the contact surface.

[0009] The groove may have an axial length greater than a thickness of the bearing.

[0010] The axial length of the groove may be less than twice the thickness of the bearing.

[0011] The groove may be curved at a predetermined curvature and have curved surfaces facing both axial ends of the bearing.

[0012] The rotating member may be a crankshaft connected to the piston via a connecting rod, and the bearing may support a shaft portion of the crankshaft.

[0013] The rotating member may be a connecting rod having both ends connected to the piston and the crankshaft, and the bearing may support one end of the connecting rod. Effect of the Invention

[0014] According to the present invention, the effect of reducing friction loss in an internal combustion engine is achieved. [Brief description of the drawings]

[0015] [Figure 1] 1 is a schematic diagram showing a schematic configuration of an internal combustion engine according to one embodiment; [Diagram 2] 2 is a schematic diagram for explaining the configuration of a bearing 40. FIG. [Diagram 3] 3 is a cross-sectional view of FIG. 2 taken along line B-B. [Figure 4] FIG. 4 is an enlarged view of a portion C in FIG. [Diagram 5] 4 is a schematic diagram showing a state in which a bearing 40 supports a journal portion 22 of a tilted crankshaft 20. FIG. [Figure 6] FIG. 6 is an enlarged view of a portion D in FIG. [Figure 7] FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0016] <Configuration of an internal combustion engine> FIG. 1 is a schematic diagram showing a schematic configuration of an internal combustion engine according to one embodiment. As an example, the internal combustion engine 1 is an engine mounted on a vehicle. The internal combustion engine 1 burns and expands a mixture of intake air (air) and fuel to generate power for running the vehicle. The internal combustion engine 1 is a diesel engine here, but is not limited thereto and may be a gasoline engine. As shown in FIG. 1, the internal combustion engine 1 has a cylinder block 10, pistons 14a to 14d, connecting rods 16a to 16d, a crankshaft 20, a support block 30, a bearing 40, and an oil pan 60.

[0017] Here, the cylinder block 10 has four cylinders 12a to 12d. However, the number of cylinders 12 in the internal combustion engine 1 is not limited to four. An intake passage for drawing in intake air and an exhaust passage for discharging exhaust gas after combustion are connected to each of the cylinders 12a to 12d.

[0018] The pistons 14a to 14d perform up and down reciprocating motion within the cylinders 12a to 12d. Specifically, the pistons 14a to 14d repeat reciprocating motion between top dead center and bottom dead center within the cylinders 12a to 12d through four strokes of intake, compression, combustion, and exhaust.

[0019] The connecting rods 16a to 16d connect the pistons 14a to 14d to the crankshaft 20. Both ends of the connecting rods 16a to 16d connect the pistons 14a to 14d to the crankshaft 20. The connecting rods 16a to 16d transmit the reciprocating motion of the pistons 14a to 14d to the crankshaft 20. Each of the connecting rods 16a to 16d has a small end connected to the piston 14a to 14d and a big end connected to the crankshaft 20.

[0020] The crankshaft 20 is a rotating member that rotates in conjunction with the reciprocating motion of the pistons 14a to 14d. The crankshaft 20 is connected to the pistons 14a to 14d via the connecting rods 16a to 16d. The crankshaft 20 converts the reciprocating motion transmitted from the pistons 14a to 14d via the connecting rods 16a to 16d into rotational motion. As shown in FIG. 1, the crankshaft 20 has a journal portion 22, an arm portion 23, and a crank pin 24.

[0021] The journal portions 22 are shaft portions of the crankshaft 20. The journal portions 22 are provided at predetermined intervals in the axial direction of the crankshaft 20. Here, five journal portions 22 are provided.

[0022] A plurality of arm portions 23 are provided at predetermined intervals in the axial direction of the crankshaft 20. The arm portions 23 are fixed to the axial end portions of the journal portions 22, and extend radially outward from the journal portions 22.

[0023] The crank pin 24 is fixed between adjacent arm portions 23 and positioned parallel to the journal portion 22. The crank pin 24 is connected to the big ends of the connecting rods 16a to 16d.

[0024] The support block 30 is a block that supports the crankshaft 20. The support block 30 is fixed to the cylinder block 10 via a fastening member. The support block 30 has a lower support portion 32 (see FIG. 2 ) that supports the journal portion 22 of the crankshaft 20. The lower support portion 32 supports the lower half of the journal portion 22 via a bearing 40. The upper half of the journal portion 22 is supported by the cylinder block 10 via the bearing 40. In this way, the journal portion 22 is surrounded by the support block 30 and the cylinder block 10.

[0025] The bearing 40 supports the crankshaft 20 on its inner circumferential surface 41. Specifically, the bearing 40 supports the journal portion 22, which is the main shaft portion of the crankshaft 20. The bearing 40 is a sliding bearing. An oil film is formed between the bearing 40 and the journal portion 22 by lubricating oil. In this embodiment, as will be described in detail later, the support block 30 and the cylinder block 10, with which the outer circumferential surface of the bearing 40 comes into contact, are configured to reduce the sliding resistance between the journal portion 22 and the bearing 40 in order to suppress an increase in friction loss when the crankshaft 20 rotates.

[0026] The oil pan 60 is located below the support block 30 and stores engine oil, which is a lubricating oil. The engine oil stored in the oil pan 60 is sucked up by a pump and can circulate throughout the internal combustion engine 1. The engine oil forms an oil film, for example, between the pistons 14a-14d and the cylinders 12a-12d, and between the journal portion 22 and the bearing 40.

[0027] <Detailed configuration of bearings and surrounding parts> Fig. 2 is a schematic diagram for explaining the configuration of bearing 40, and is a cross-sectional view taken along line AA in Fig. 1. Fig. 3 is a cross-sectional view taken along line BB in Fig. 2. Fig. 4 is an enlarged view of portion C in Fig. 3. For ease of explanation, Figs. 2 to 4 show the thin-walled bearing 40 to be thicker than it actually is.

[0028] Since the five bearings 40 have the same configuration, one bearing 40 will be described as an example. The bearing 40 supports the journal portion 22 of the crankshaft 20. As shown in Fig. 2, the inner peripheral surface 41 of the bearing 40 faces the outer peripheral surface of the journal portion 22 of the crankshaft 20 with a small gap therebetween. An oil film of lubricating oil is formed in the gap.

[0029] 2, the outer peripheral surface 42 of the bearing 40 is in contact with the cylinder block 10 and the support block 30. Specifically, the outer peripheral surface 42 of the upper half of the bearing 40 is in contact with the upper support portion 18 of the cylinder block 10, and the outer peripheral surface 42 of the lower half of the bearing 40 is in contact with the lower support portion 32 of the support block 30. In this embodiment, the upper support portion 18 and the lower support portion 32 function as a housing (hereinafter referred to as housing 50) in contact with the outer peripheral surface 42 of the bearing 40. The bearing 40 can be divided into an upper half and a lower half.

[0030] The housing 50 supports the journal portion 22 via the bearing 40. As shown in Fig. 3, the housing 50 has a contact surface 52 that contacts the outer peripheral surface 42 of the bearing 40. The contact surface 52 contacts a portion of the outer peripheral surface 42 of the bearing 40 excluding both axial ends (i.e., the central portion of the bearing 40).

[0031] As shown in Fig. 3, the housing 50 has a groove 55 formed in a portion of the outer peripheral surface 42 of the bearing 40 facing both axial ends (one end 46 and the other end 47). The cross-sectional shape of the groove 55 is rectangular (specifically, oblong) as shown in Fig. 4. Therefore, the bottom surface of the groove 55 is parallel to the contact surface 52 of the housing 50.

[0032] 3, the grooves 55 are located on both sides of the contact surface 52 of the housing 50 in the axial direction and are recessed from the contact surface 52. Due to the presence of the grooves 55, the axial ends (one end 46 and the other end 47) of the bearing 40 are not in contact with the housing 50.

[0033] The groove portion 55 is formed over one circumference of the bearing 40 in the circumferential direction. Therefore, one end 46 and the other end 47 of the bearing 40 are not in contact with the housing 50 over the entire circumference. As shown in FIG. 4, the axial length L1 of the groove portion 55 is greater than the thickness L2 of the bearing 40. The thickness L2 of the bearing 40 is the thickness between the inner peripheral surface 41 and the outer peripheral surface 42 of the bearing 40. However, the present invention is not limited to this, and the axial length L1 of the groove portion 55 may be smaller than the thickness L2 of the bearing 40.

[0034] In the case where the housing 50 is provided with the groove 55, when the crankshaft 20 is tilted and the journal portion 22 comes into contact with the axial end portion (one end portion 46 or the other end portion 47) of the bearing 40, the axial end portion that is not in contact with the housing 50 is deformed by receiving a load from the journal portion 22 due to the presence of the groove 55. By deforming the axial end portion in this manner, the pressure (hereinafter also referred to as surface pressure) that the axial end portion receives from the journal portion 22 can be reduced compared to when the axial end portion is in contact with the housing 50.

[0035] Here, the cause of the tilt of the crankshaft 20 will be explained. When the pistons 14a to 14d reciprocating up and down reach bottom dead center, a downward force acts on the crankshaft 20 from the pistons 14a to 14d via the crankpin 24. This force causes the crankshaft 20 to tilt. When the crankshaft 20 tilts, the journal portion 22, which is originally parallel to the bearing 40, also tilts.

[0036] Unlike this embodiment, if the housing 50 does not have the groove 55, the inclined journal portion 22 presses against the one end 46 or the other end 47 that is in contact with the housing 50, and the surface pressure acting from the journal portion 22 to the one end 46 or the other end 47 increases. If the crankshaft 20 continues to rotate in this state, the sliding resistance between the journal portion 22 and the bearing 40 increases, resulting in increased friction loss.

[0037] FIG. 5 is a schematic diagram showing a state in which the bearing 40 supports the journal portion 22 of the tilted crankshaft 20. FIG. 6 is an enlarged view of a portion D in FIG. 5. In the case where the groove portion 55 is provided in the housing 50 as in this embodiment, when a load acts on one end 46 of the bearing 40 from the tilted journal portion 22 as shown in FIG. 5, the one end 46 that is not in contact with the housing 50 is deformed as shown in FIG. 6. Specifically, the one end 46 is deformed so as to enter the groove portion 55. As a result, the surface pressure acting on the one end 46 from the journal portion 22 is smaller than when the one end 46 is sandwiched between the housing 50 and the journal portion 22. In addition, the surface pressure can be reduced by the journal portion 22 coming into surface contact with the deformed one end 46. As a result, the sliding resistance between the journal portion 22 and the one end 46 of the bearing 40 is also reduced, and the friction loss can also be reduced. In addition, since the surface pressure acting from the journal portion 22 to the one end portion 46 is reduced, the oil film on the one end portion 46 can be prevented from becoming thin.

[0038] It is desirable that the axial length L1 of the groove 55 is smaller than twice the thickness L2 of the bearing 40. As an example, the axial length L1 of the groove 55 is 3 mm, and the thickness L2 of the bearing 40 is 2 mm. If the axial length L1 of the groove 55 is too long, the contact surface 52 of the housing 50 that contacts the outer circumferential surface 42 of the bearing 40 becomes narrow, and the function of the bearing 40 to support the journal portion 22 may be reduced. In response to this, by making the axial length L1 of the groove 55 smaller than twice the thickness L2 of the bearing 40, it is possible to prevent the function of the bearing 40 from being reduced and to suppress a reduction in friction loss.

[0039] The depth L3 of the groove 55 (i.e., the length in the radial direction in the axial direction) is set so that the deformed one end 46 and the other end 47 do not come into contact with the bottom surface of the groove 55. As an example, the depth L3 of the groove 55 is 0.5 mm, which is smaller than 1 / 2 the thickness L2 of the bearing 40.

[0040] In the above description, the cross-sectional shape of the groove 55 is rectangular, but is not limited to this. For example, the cross-sectional shape of the groove 75 may be as shown in FIG. FIG. 7 is a schematic diagram showing a modified example. As shown in FIG. 7, the groove portion 75 according to the modified example has a curved surface 76 curved at a predetermined curvature. The curved surface 76 is a surface facing the axial end portions (one end portion 46 and the other end portion 47) of the bearing 40. In the case where such a groove portion 75 is provided, when a load acts on the axial end portion of the bearing 40 from the tilted journal portion 22 (see FIG. 6), the axial end portion deforms along the curved surface 76. Specifically, the axial end portion deforms while contacting the curved surface 76. Therefore, the journal portion 22 comes into surface contact with the deformed axial end portion, thereby making it possible to reduce the surface pressure acting on the bearing 40.

[0041] In the above description, the bearing 40 supports the journal portion 22 of the crankshaft 20, which is a rotating member, but this is not limiting. For example, the bearing 40 may be provided in the large diameter portion of the connecting rod 16a to 16d that is connected to the crank pin 24 of the crankshaft 20. In this case, by providing a groove portion 55 in the large diameter portion that contacts the outer circumferential surface of the bearing 40, friction loss due to contact between the connecting rod 16a to 16d and the crankshaft 20 can be suppressed. The bearings 40 may be provided in small diameter portions of the connecting rods 16a to 16d that are connected to the pistons 14a to 14d. That is, the bearings 40 support the ends of the connecting rods 16a to 16d, which are rotating members.

[0042] <Effects of this embodiment> The internal combustion engine 1 of the embodiment described above includes a bearing 40 that supports a rotating member (the crankshaft 20, as an example) that rotates in conjunction with the reciprocating motion of the pistons 14a to 14d, and a housing 50 that contacts an outer circumferential surface 42 of the bearing 40. The housing 50 has grooves 55 located in portions of the outer circumferential surface 42 of the bearing 40 that face both axial ends of the outer circumferential surface 42 of the bearing 40. With the above-mentioned configuration, when the crankshaft 20 is tilted by an external force and a load acts on the axial end (one end 46 or the other end 47) of the bearing 40 from the journal portion 22, the axial end that is not in contact with the housing 50 is deformed due to the presence of the groove portion 55. As a result, the surface pressure acting on the axial end from the journal portion 22 is smaller than when the axial end is sandwiched between the housing 50 and the journal portion 22. In addition, the surface pressure can be reduced by the journal portion 22 coming into surface contact with the deformed axial end. As a result, the sliding resistance between the journal portion 22 and the axial end of the bearing 40 is also reduced, and friction loss can also be reduced.

[0043] Although the present invention has been described above using the embodiments, the technical scope of the present invention is not limited to the scope described in the above embodiments, and various modifications and changes are possible within the scope of the gist of the present invention. For example, all or part of the device can be configured by distributing or integrating functionally or physically in any unit. In addition, new embodiments resulting from any combination of multiple embodiments are also included in the embodiments of the present invention. The effect of the new embodiment resulting from the combination combines the effect of the original embodiment. [Explanation of symbols]

[0044] 1. Internal combustion engine 12a~12d Cylinder 14a~14d Piston 16a~16d Connecting rod 20 Crankshaft 22 Journal Section 40 Bearings 41 Inner surface 42 Outer surface 46 One end 47 Other end 50 Housing 52 Contact surface 55 Groove

Claims

1. a rotating member that rotates in conjunction with the reciprocating motion of a piston in a cylinder; A bearing that supports the rotating member on an inner circumferential surface thereof; a housing in contact with an outer peripheral surface of the bearing; Equipped with the housing has grooves in portions facing both axial ends of the outer circumferential surface of the bearing.

2. The groove portion is formed around one circumference of the bearing in the circumferential direction.

2. The internal combustion engine of claim 1.

3. the housing has a contact surface in contact with an axial center portion of an outer circumferential surface of the bearing, The groove is recessed from the contact surface.

2. The internal combustion engine of claim 1.

4. The axial length of the groove is greater than the thickness of the bearing.

2. The internal combustion engine of claim 1.

5. The axial length of the groove is less than twice the thickness of the bearing.

5. An internal combustion engine according to claim 4.

6. The groove portion is curved at a predetermined curvature and has curved surfaces facing both axial ends of the bearing.

2. The internal combustion engine of claim 1.

7. the rotating member is a crankshaft connected to the piston via a connecting rod, The bearing supports a shaft portion of the crankshaft.

2. The internal combustion engine of claim 1.

8. the rotating member is a connecting rod having both ends connected to the piston and the crankshaft, The bearing supports an end of the connecting rod.

2. The internal combustion engine of claim 1.

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