Balancer device for internal combustion engine

Abstract

To provide a balancer device for an internal combustion engine capable of preventing the flying-up of oil due to the rotation of a crank shaft while reducing the size of the internal combustion engine.SOLUTION: A baffle plate 12 of a balancer device includes a deepest part 12A located at the center of the baffle plate 12 in the direction crossing the axial direction of a balancer shaft 5, curved parts 12B, 12C curved from the deepest part 12A to the upper side toward both outsides in the direction crossing the balancer shaft 5, opening parts 12a, 12b formed in the deepest part 12A while protruding the upper part of the balancer shaft 5 upward, ribs 12c, 12d protruded upward from the baffle plate 12 and arranged on both outsides of the opening parts 12a, 12b, and oil drop holes 12e, 12f, 12g, 12h arranged on both outsides of the ribes 12c, 12d and located downward of the ribs 12c, 12d.SELECTED DRAWING: Figure 5

Description

[Technical field]

[0001] The present invention relates to a balancer device for an internal combustion engine. [Background technology]

[0002] 2. Description of the Related Art A balancer device for an internal combustion engine is known in which a balancer shaft is rotated together with a balance weight to suppress vibration of a crankshaft that occurs with the movement of pistons (see Patent Document 1).

[0003] In the internal combustion engine described in Patent Document 1, an oil pan for storing oil is fixed below a cylinder block, and a balancer device is disposed inside the oil pan below the crankshaft.

[0004] More specifically, the balancer device has a structure in which a single balancer shaft is disposed below the crankshaft, and the balancer device includes a baffle plate that covers the balancer device from above. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2019-138260 A Summary of the Invention [Problem to be solved by the invention]

[0006] However, in conventional balancer devices for internal combustion engines, a baffle plate is provided to cover the balancer device from above, and so the balancer device must be positioned lower to avoid interference between the baffle plate and the crankshaft, which increases the vertical dimension of the engine and may result in an increased engine size.

[0007] Furthermore, if the baffle plate is placed too close to the crankshaft in order to reduce the vertical dimension of the engine, oil that has accumulated on the baffle plate may be stirred up as the crankshaft rotates.

[0008] The present invention has been made in consideration of the above-mentioned problems, and aims to provide a balancer device for an internal combustion engine that can prevent oil from being splashed up by the rotation of the crankshaft while reducing the size of the internal combustion engine. [Means for solving the problem]

[0009] The present invention provides a balancer device for an internal combustion engine that is arranged between a crankcase in which a crankshaft is arranged and an oil pan that is fixed to a lower part of the crankcase and has an opening at an upper end, and includes a balancer housing having a balancer shaft arranged below the crankshaft, a bearing part that rotatably supports the balancer shaft, and a baffle plate that covers the opening of the oil pan, and is characterized in that the baffle plate has a deepest part that is located in the center of the baffle plate in a direction intersecting with the axial direction of the balancer shaft and is located at the deepest part of the baffle plate, a curved part that curves upward from the deepest part toward both outsides in a direction intersecting with the balancer shaft, a first opening formed in the deepest part and causing at least an upper part of the balancer shaft to protrude upward, ribs that protrude upward from the baffle plate and extend in the axial direction of the balancer shaft and are arranged on both outsides relative to the first opening, and a second opening that is arranged on both outsides relative to the ribs, is located below the ribs, and penetrates the baffle plate. Effect of the Invention

[0010] As described above, according to the present invention, it is possible to reduce the size of the internal combustion engine while preventing oil from being splashed up by the rotation of the crankshaft. [Brief description of the drawings]

[0011] [Figure 1]FIG. 1 is a front view of an engine equipped with a balancer device according to an embodiment of the present invention. [Diagram 2] FIG. 2 is a cross-sectional view taken along the line II-II of FIG. [Diagram 3] FIG. 3 is a cross-sectional view taken along the line III-III in FIG. [Figure 4] FIG. 4 is a cross-sectional view taken along the line IV-IV in FIG. [Diagram 5] FIG. 5 is a perspective view of a balancer device according to an embodiment of the present invention. [Figure 6] 6 is a cross-sectional view taken along the line VI-VI in FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] A balancer device for an internal combustion engine according to one embodiment of the present invention is a balancer device for an internal combustion engine that is arranged between a crankcase in which a crankshaft is arranged, and an oil pan that is fixed to the lower part of the crankcase and has an opening at its upper end, and includes a balancer housing having a balancer shaft arranged below the crankshaft, a bearing portion that rotatably supports the balancer shaft, and a baffle plate that covers the opening of the oil pan, and the baffle plate includes a deepest portion that is located in the center of the baffle plate in a direction intersecting the axial direction of the balancer shaft and is located at the deepest part of the baffle plate, a curved portion that curves upward from the deepest portion toward both outsides in the direction intersecting the balancer shaft, a first opening formed in the deepest portion and causing at least an upper part of the balancer shaft to protrude upward, ribs that protrude upward from the baffle plate and extend in the axial direction of the balancer shaft and are arranged on both outsides of the first opening, and second openings that are arranged on both outsides of the ribs, are located below the ribs and penetrate the baffle plate.

[0013] As a result, the balancer device for an internal combustion engine according to one embodiment of the present invention can prevent oil from being splashed up due to rotation of the crankshaft while enabling the internal combustion engine to be made more compact. EXAMPLES

[0014] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an embodiment of a balancer device for an internal combustion engine according to the present invention will be described with reference to the drawings. 1 to 6 are diagrams showing a balancer device for an internal combustion engine according to one embodiment of the present invention.

[0015] 1 to 6, the up / down, front / rear, left / right directions are based on the crankshaft of the internal combustion engine, with the direction along the crankshaft being the front / rear direction, the direction in which the intake side and the exhaust side are located being the left / right direction, and the height direction of the internal combustion engine being the up / down direction.

[0016] First, the configuration will be described. In FIG. 1, engine 1 as an internal combustion engine includes a cylinder block 2, a cylinder head 3 provided on the upper part of the cylinder block 2, a cylinder head cover (not shown) provided on the upper part of the cylinder head 3, and an oil pan 4 provided on the lower part of the cylinder block 2 in which oil is stored.

[0017] Specifically, a crankcase 2B that defines a crank chamber 2A is provided below the cylinder block 2, and an oil pan 4 is fixed to the bottom of the crankcase 2B by bolts (not shown).

[0018] As shown in FIG. 2, the cylinder block 2 is provided with a plurality of cylinders 2S, pistons (not shown) housed in the cylinders 2S so as to be able to move up and down freely, and a crankshaft 8 that converts the up and down movement of the pistons into rotational motion via connecting rods (not shown). The crankshaft 8 is disposed in a crankcase 2B.

[0019] That is, a crank chamber 2A is formed between the crankcase 2B and the oil pan 4, and the crankshaft 8 is disposed in the crank chamber 2A. The cylinder head 3 is provided with an intake camshaft equipped with an intake cam, and an exhaust camshaft disposed parallel to the intake camshaft and equipped with an exhaust cam, neither of which are shown in the figure.

[0020] The crankshaft 8 includes a crank pin 8a to which a connecting rod is connected via a sliding bearing 7, a crank journal 8b that is rotatably supported by an upper journal bearing portion 2D provided on the cylinder block 2 and a lower journal bearing portion 2E fixed to the upper journal bearing portion 2D, and a counterweight 8c that connects the crank pin 8a and the crank journal 8b and balances the rotation of the crankshaft 8.

[0021] An opening 4a is formed at the upper end of the oil pan 4, and the upper end of the oil pan 4 opens upward. As a result, the oil that has lubricated objects to be lubricated, including the pistons and the intake and exhaust camshafts, is collected from the cylinder block 2 through the opening 4a into the oil pan 4 and stored in the oil pan 4.

[0022] As shown in FIG. 2, a balancer shaft 5 is disposed below the crankshaft 8 and is located above the oil pan 4.

[0023] The balancer shaft 5 extends parallel to the crankshaft 8, and is arranged vertically aligned with the crankshaft 8. In other words, the balancer shaft 5 is arranged directly below the crankshaft 8.

[0024] 1 and 2, a balancer gear 5A is provided at the front end of the balancer shaft 5. A crank gear 8A is provided at the front end of the crankshaft 8, and the crank gear 8A meshes with the balancer gear 5A.

[0025] The crank gear 8A and the balancer gear 5A are formed with the same number of teeth. The balancer shaft 5 rotates in synchronism with the rotation of the crankshaft 8, that is, in the opposite direction at the same rotation speed.

[0026] As shown in FIG. 5, balance weights 5B and 5C are provided at the front and rear ends of the balancer shaft 5, respectively, and the balance weights 5B and 5C are each formed to have a mass smaller than the mass of the counterweight 8c.

[0027] The balancer shaft 5 has a shaft portion 5D having a smaller diameter than the balance weights 5B, 5C, and the balance weights 5B, 5C are provided at the front and rear ends (both ends) of the shaft portion 5D. That is, the balancer shaft 5 has the shaft portion 5D and the balance weights 5B, 5C attached to the front and rear ends, respectively, of the shaft portion 5D and having a larger rotation radius than the shaft portion 5D.

[0028] In order to cancel out vibrations caused by the reciprocating motion of the pistons, etc., the balancer shaft 5 rotates in synchronization with the crankshaft 8 at a constant speed in the opposite direction to the rotational direction of the crankshaft 8. This generates a load (exciting force) in a direction that cancels out vibrations caused by the reciprocating motion of the pistons, etc., and cancels out the periodic rotational vibrations (primary vibrations) of the crankshaft 8.

[0029] A balancer housing 10 is provided on the engine 1 (see Figs. 3 to 5). The balancer shaft 5 and the balancer housing 10 of this embodiment constitute a balancer device.

[0030] The balancer housing 10 has a balancer body 11 and a baffle plate 12. The balancer body 11 has a front body portion 11A and a rear body portion 11B that are separated in the front-rear direction and extend in the left-right direction.

[0031] Boss-shaped fixing portions 11a are formed on the left and right ends of the front body portion 11A and the rear body portion 11B (see FIG. 5). The fixing portions 11a are fastened to the crankcase 2B by bolts 20A (see FIG. 3), thereby attaching the balancer housing 10 to the crankcase 2B.

[0032] As shown in FIGS. 2 and 3, the balancer housing 10 has bearings 11C and 11D provided on the front body portion 11A and the rear body portion 11B, respectively, which support the shaft portion 5D of the balancer shaft 5 so that it can rotate freely.

[0033] The bearing portions 11C, 11D are composed of a semicircular bearing surface 11b formed on the underside of the front body portion 11A and the rear body portion 11B, and a lower bearing portion 11E fastened to the lower portion of the front body portion 11A and the rear body portion 11B by bolts 20B and having a semicircular bearing surface 11c continuous with the bearing surface 11b.

[0034] The balancer shaft 5 is sandwiched between the bearing surfaces 11b and 11c, and is thereby rotatably supported by the bearing portions 11C and 11D.

[0035] As shown in FIG. 5, the baffle plate 12 is disposed between the front body portion 11A and the rear body portion 11B, and extends in the left-right direction along the front body portion 11A and the rear body portion 11B.

[0036] The front end of the baffle plate 12 is connected to the front main body portion 11A, and the rear end of the baffle plate 12 is connected to the rear main body portion 11B, and the baffle plate 12 is formed integrally with the front main body portion 11A and the rear main body portion 11B.

[0037] A balancer gear accommodating portion 11F is provided at the front end portion of the front main body portion 11A. The balancer gear accommodating portion 11F is formed of a semicircular member that is open at the upper end and curved along the outer diameter of the balancer gear 5A.

[0038] The balancer gear housing portion 11F houses a balancer gear 5A and a balance weight 5B.

[0039] The shaft portion 5D of the balancer shaft 5 is disposed on the upper part of the oil pan 4, and is located in a position where it is not immersed in the oil stored in the oil pan 4. This makes it possible to reduce the agitation resistance caused by the oil when the balancer shaft 5 rotates.

[0040] On the other hand, the balancer gear 5A and the balance weight 5B are accommodated in a balancer gear accommodating portion 11F. In other words, the balancer gear 5A and the balance weight 5B are immersed in the oil stored in the oil pan 4, but the amount of oil stirred when the balancer gear 5A and the balance weight 5B rotate is reduced, thereby reducing the stirring resistance.

[0041] In FIG. 6, when viewed from the axial direction of the balancer shaft 5, the baffle plate 12 has a deepest part 12A and curved parts 12B and 12C.

[0042] The deepest part 12A is provided in the center of the baffle plate 12 in a direction (left-right direction) intersecting with the axial direction of the balancer shaft 5, and is the part located at the lowermost position of the baffle plate 12. Here, the direction intersecting with the axial direction of the balancer shaft 5 means a direction intersecting with the axial direction of the balancer shaft 5 in a horizontal plane.

[0043] The curved portions 12B and 12C are curved upward at a small inclination angle from the deepest portion 12A toward both outer sides (left and right sides) in a direction intersecting with the balancer shaft 5. In other words, the central portion of the baffle plate 12 in a direction intersecting with the axial direction of the balancer shaft 5 is located at the lowest position, and the left and right ends are located at the highest positions.

[0044] 4 and 5, a bridge portion 12D is formed on the baffle plate 12. The bridge portion 12D is formed in the center of the baffle plate 12 in the axial direction of the balancer shaft 5, and the bridge portion 12D covers the upper side of the balancer shaft 5.

[0045] 4 to 6, openings 12a and 12b are formed in the baffle plate 12, and the openings 12a and 12b are formed in the deepest part 12A. The opening 12a opens from the front main body part 11A to the bridge part 12D, and the upper part of the shaft part 5D protrudes upward from the opening 12a.

[0046] The opening 12b opens from the rear main body portion 11B to the bridge portion 12D, and the upper portion of the shaft portion 5D protrudes upward from the opening 12b.

[0047] The bridge portion 12D is located above the openings 12a and 12b, and the upper portion of the shaft portion 5D protrudes upward from the openings 12a and 12b without contacting the bridge portion 12D.

[0048] Furthermore, the balancer housing 10 has a bridge portion 12D formed between the openings 12a, 12b in the axial direction of the balancer shaft 5, thereby preventing the openings 12a, 12b from reducing the rigidity of the baffle plate 12. In other words, the baffle plate 12 is reinforced by the bridge portion 12D.

[0049] 4 and 5, ribs 12c and 12d are formed on the curved portions 12B and 12C of the baffle plate 12. The ribs 12c and 12d are disposed on both outer sides (left and right sides) of the openings 12a and 12b. The ribs 12c and 12d protrude upward from the baffle plate 12 and extend in the axial direction of the balancer shaft 5 between the front body portion 11A and the rear body portion 11B.

[0050] Oil drop holes 12e, 12f, 12g, and 12h are formed in the baffle plate 12. The oil drop holes 12e, 12f, 12g, and 12h are disposed on both outer sides of the ribs 12c and 12d, and penetrate the baffle plate 12 so as to be located lower than the ribs 12c and 12d.

[0051] In other words, the ribs 12c and 12d protrude upward further than the oil pits 12e, 12f, 12g and 12h, and the openings 12a and 12b and the oil pits 12e, 12f, 12g and 12h are partitioned in the left-right direction by the ribs 12c and 12d.

[0052] In this embodiment, the openings 12a and 12b form first openings, and the oil pits 12e, 12f, 12g, and 12h form second openings.

[0053] Next, the operation and effect of the balancer device for the engine 1 according to this embodiment will be described. The balancer device includes a balancer housing 10 having a balancer shaft 5 arranged below the crankshaft 8, bearing portions 11C and 11D that rotatably support the balancer shaft 5, and a baffle plate 12 that covers the opening 4a of the oil pan 4.

[0054] Baffle plate 12 has a deepest portion 12A which is located at the center of baffle plate 12 in a direction intersecting the axial direction of balancer shaft 5 and is located at the deepest portion of baffle plate 12, curved portions 12B, 12C which curve upward from deepest portion 12A to both outside sides in the direction intersecting balancer shaft 5, and openings 12a, 12b formed in deepest portion 12A which allow the upper part of balancer shaft 5 to protrude upward.

[0055] In addition, the baffle plate 12 has ribs 12c, 12d which protrude upward from the baffle plate 12 and extend in the axial direction of the balancer shaft 5 and are arranged on both outer sides of the openings 12a, 12b, and oil pits 12e, 12f, 12g, 12h which are arranged on both outer sides of the ribs 12c, 12d and pass through the baffle plate 12 so as to be positioned lower than the ribs 12c, 12d.

[0056] In this way, openings 12a, 12b are formed in the center of baffle plate 12 in a direction intersecting the axial direction of balancer shaft 5, and the upper part of shaft portion 5D of balancer shaft 5 protrudes upward from openings 12a, 12b, so that balancer shaft 5 can be brought closer to crankshaft 8 in the vertical direction, and the vertical dimension of engine 1 can be shortened. As a result, engine 1 can be made more compact.

[0057] In addition, the baffle plate 12 has curved portions 12B, 12C that curve upward from the deepest part 12A toward both outsides in the direction intersecting the balancer shaft 5, and ribs 12c, 12d that protrude upward from the baffle plate 12 and extend in the axial direction of the balancer shaft 5 and are positioned on both outsides of the openings 12a, 12b. Therefore, after falling onto the baffle plate 12, the oil (see oil O1 in Figure 6) that flows toward the deepest part 12A can be blocked by the ribs 12c, 12d.

[0058] This makes it possible to prevent oil from flowing into the openings 12a and 12b, and to prevent the oil from scattering around due to the rotation of the balancer shaft 5.

[0059] In addition, the baffle plate 12 has oil drop holes 12e, 12f, 12g, and 12h that are positioned on both outer sides of the ribs 12c and 12d and penetrate the baffle plate 12 so as to be located lower than the ribs 12c and 12d, so that the oil blocked by the ribs 12c and 12d can be returned to the oil pan 4 through the oil drop holes 12e, 12f, 12g, and 12h that are located away from the balancer shaft 5 (see oil O2 in Figure 6).

[0060] This prevents oil from accumulating on the upper surface of the baffle plate 12, and prevents the oil from being stirred up by the rotation of the crankshaft 8 even when the balancer shaft 5 is brought closer to the crankshaft 8 to shorten the vertical dimension of the engine 1.

[0061] In this manner, the balancer device of this embodiment can prevent oil from being splashed up due to the rotation of the crankshaft 8 while achieving a reduction in the size of the engine 1 .

[0062] Furthermore, according to the balancer device of the engine 1 of this embodiment, the balancer shaft 5 has a shaft portion 5D and balance weights 5B, 5C attached to both ends of the shaft portion 5D, respectively, and having a larger radius of rotation than the shaft portion 5D, and the upper portion of the shaft portion 5D protrudes upward beyond the openings 12a, 12b.

[0063] As a result, by making the upper part of shaft portion 5D, which has a smaller rotation radius than balance weights 5B, 5C, protrude upward from openings 12a, 12b, balancer shaft 5 can be brought closer to crankshaft 8 in the vertical direction more effectively, and the vertical dimension of engine 1 can be shortened more effectively. As a result, engine 1 can be made more compact.

[0064] In the balancer shaft 5, the upper part of the shaft portion 5D protrudes upward from the openings 12a and 12b, but the upper part of the shaft portion 5D may protrude upward from the openings 12a and 12b from the vertical center. In other words, it is sufficient that at least the upper part of the shaft portion 5D protrudes upward from the openings 12a and 12b.

[0065] Although an embodiment of the invention has been disclosed, it will be apparent to one skilled in the art that modifications may be made without departing from the spirit and scope of the invention, and all such modifications and equivalents are intended to be encompassed by the following claims. [Explanation of symbols]

[0066] 1...engine (internal combustion engine), 2B...crankcase, 4...oil pan, 4a...opening, 5...balancer shaft, 5B, 5C...balance weight, 5D...shaft, 8...crankshaft, 10...balancer housing (balancer device), 11C, 11D...bearing, 12...baffle plate (balancer device), 12A...deepest part, 12a, 12b...opening (first opening), 12B, 12C...curved part, 12c, 12d...rib, 12e, 12f, 12g, 12h...oil drop (second opening)

Claims

1. A balancer device for an internal combustion engine, which is disposed between a crankcase in which a crankshaft is disposed, and an oil pan which is fixed to a lower portion of the crankcase and has an opening at an upper end, a balancer shaft disposed below the crankshaft; a balancer housing having a bearing portion that rotatably supports the balancer shaft and a baffle plate that covers the opening of the oil pan, The baffle plate has a deepest portion located at a center of the baffle plate in a direction intersecting an axial direction of the balancer shaft, the deepest portion being located at a deepest portion of the baffle plate; a curved portion curved upward from the deepest portion toward both outer sides in a direction intersecting with the balancer axis; a first opening formed in the deepest portion and allowing at least an upper portion of the balancer shaft to protrude upward; Ribs protruding upward from the baffle plate, extending in an axial direction of the balancer shaft, and disposed on both outer sides of the first opening; a second opening disposed on both outer sides of the ribs and positioned lower than the ribs and penetrating the baffle plate.

2. The balancer shaft is A shaft portion and balance weights attached to both ends of the shaft portion and having a larger rotation radius than the shaft portion, 2. A balancer device for an internal combustion engine according to claim 1, wherein an upper portion of said shaft portion projects upward beyond said first opening portion.

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