Balancing device for internal combustion engine

Abstract

To provide a balancer device for an internal combustion engine capable of suppressing increase in rotational resistance and increase in consumption of lubrication oil in an engagement portion between a reduction gear and a pump driving gear by inhibiting the pump driving gear for rotating and driving an oil pump from being splashed with the lubrication oil.SOLUTION: A balancer device for an internal combustion engine includes: an upper side housing mounted to the internal combustion engine; a lower side housing fixed to the upper side housing; a balancer body accommodated in a space formed between the upper side housing and the lower side housing; and an oil pump fixed at least to the upper side housing. An end surface of the upper side housing and an end surface of the oil pump are mounted so as to come in contact with each other. An end surface of the lower side housing and the end surface of the oil pump are mounted so as to form a predetermined gap therebetween.SELECTED DRAWING: Figure 7

Description

[Technical field]

[0001] The present invention relates to a balancer device for an internal combustion engine, and more particularly to a balancer device for an internal combustion engine equipped with an oil pump, and a balancer device with an oil pump. [Background technology]

[0002] In a typical internal combustion engine, a balancer device is provided that rotatably houses a first balancer shaft driven by a crankshaft and a second balancer shaft driven by the first balancer shaft, and this balancer device is used to reduce vibrations generated in the internal combustion engine.

[0003] Furthermore, the first balancer shaft and the second balancer shaft are provided with balance weights, and the first balancer shaft and the second balancer shaft are rotated at twice the rotation speed of the crankshaft to balance the inertial force generated in the crankshaft with the inertial force generated in the first balancer shaft and the second balancer shaft, thereby reducing vibration in the internal combustion engine.

[0004] It is also known that in this balancer device, as described in JP 2010-230129 A (Patent Document 1), the balancer device is fastened to the lower part of the internal combustion engine body and placed inside the oil pan, and the first of the two balancer shafts is rotated and driven by the crankshaft, and the first balancer shaft drives the second balancer shaft via a synchronous gear transmission means, and the second balancer shaft drives the oil pump.

[0005] In this balancer device, a first balancer shaft and a second balancer shaft are arranged in parallel, and a gear transmission mechanism in which a first gear and a second gear are meshed with each other is provided on one end of the first balancer shaft and the second balancer shaft. In this case, the first gear and the second gear have the same number of teeth, and the first balancer shaft and the second balancer shaft rotate synchronously at the same rotation speed.

[0006] A balancer drive gear is provided at the other end of the first balancer shaft, and a reduction gear for driving an oil pump is provided at the other end of the second balancer shaft, and this reduction gear is engaged with a pump drive gear fixed to the rotating shaft of the oil pump. Since the engine side gear rotated by the internal combustion engine is engaged with the balancer drive gear of the first balance shaft, when the engine side gear is rotated by the internal combustion engine, this rotation is transmitted from the balancer drive gear to the first balancer shaft to the first gear to the second gear to the second balancer shaft to the reduction gear to the pump drive gear, and finally the oil pump is rotated. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] JP 2010-230129 A Summary of the Invention [Problem to be solved by the invention]

[0008] The above-mentioned balancer drive gear, first balancer shaft, first gear, second gear, second balancer shaft, and reduction gear are placed on the lower housing and covered by the upper housing which is combined with the lower housing, and are stored in the space formed by both housings.

[0009] However, since the engine side gear meshes with the balancer drive gear from above, the upper housing in the area where the balancer drive gear and the pump drive gear arranged adjacent to it are located is cut out and opened.

[0010] Furthermore, because the balancer device is placed inside an oil pan below the internal combustion engine, lubricating oil dripping from the internal combustion engine, which is located above the balancer device, falls through the cut-out open portion of the upper housing onto the balancer drive gear and the pump drive gear located adjacent to it.

[0011] Here, the balancer drive gear is unavoidable because it meshes with the engine gear, but if more lubricating oil than necessary falls on the pump drive gear that rotates the oil pump, the viscosity of the lubricating oil will cause an increase in rotational resistance at the meshing point with the reduction gear. Since the viscosity of the lubricating oil is particularly high at low temperatures, this increase in rotational resistance cannot be ignored from the standpoint of fuel economy, etc.

[0012] In addition, the pump drive gear stirs the lubricating oil, causing it to splash out from the open part of the upper housing, and the lubricating oil is stirred up toward the top of the engine, resulting in increased oil consumption.

[0013] An object of the present invention is to provide a new balancer device for an internal combustion engine, and a balancer device with an oil pump, which can minimize the amount of lubricating oil that falls on the pump drive gear that rotates the oil pump, thereby suppressing an increase in rotational resistance at the meshing portion between the reduction gear and the pump drive gear and an increase in oil consumption. [Means for solving the problem]

[0014] The present invention is characterized in that it comprises an upper housing attached to an internal combustion engine, a lower housing fixed to the underside of the upper housing, a balancer body housed in a space formed between the upper housing and the lower housing, and an oil pump fixed to at least the upper housing, wherein a pump drive gear and a reduction gear for driving the pump drive gear are arranged between the upper housing and the oil pump, and the end face of the upper housing and the end face of the oil pump are attached in a form in which they come into contact with each other so as to cover the pump drive gear and the reduction gear, and the end face of the lower housing and the end face of the oil pump are attached with a predetermined gap between them. Effect of the Invention

[0015] According to the present invention, it is possible to minimize the amount of lubricating oil that falls on the pump drive gear that rotates the oil pump, thereby suppressing an increase in rotational resistance at the meshing portion between the reduction gear and the pump drive gear.In addition, by stirring the lubricating oil by the pump drive gear, it is possible to suppress the scattering of lubricating oil from the open portion of the upper housing, thereby suppressing an increase in oil consumption due to lubricating oil being swept up above the engine. [Brief description of the drawings]

[0016] [Figure 1] 1 is a configuration diagram showing an internal combustion engine provided with a balancer device; [Diagram 2] 1 is an external perspective view of a balancer device according to an embodiment of the present invention, viewed obliquely from above. FIG. [Diagram 3] FIG. 3 is a top view of the balancer device shown in FIG. 2, as viewed from the internal combustion engine side. [Figure 4] 3 is a bottom view of the balancer device shown in FIG. 2 as viewed from the oil pan side. [Diagram 5] 3 is a top view of the balancer device shown in FIG. 2 with an upper housing removed. FIG. [Figure 6] 4 is a side view of the balancer device shown in FIG. 3, taken along plane AA, as viewed from the oil pump side. [Figure 7] FIG. 7 is an external perspective view of the balancer device shown in FIG. 6, as viewed obliquely from above. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0017] Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings. However, the present invention is not limited to the following embodiment, and various modifications and application examples within the technical concept of the present invention are also included within its scope.

[0018] Before describing the embodiment of the present invention, the installation state of the internal combustion engine and the balancer device will be briefly described with reference to Fig. 1. Note that this figure only shows the relationship between the internal combustion engine and the balancer device, and is not the actual balancer device of this embodiment described below.

[0019] 1 shows an internal combustion engine 01, which may be, for example, an in-line four-cylinder reciprocating internal combustion engine. A cylinder block 03 is provided below a cylinder head 02, and a cylinder block 04 is fixed to the underside of the cylinder block 03. A crankshaft (not shown) is rotatably supported by the cylinder block 04, and the axial direction of the crankshaft is aligned along the front-rear direction of the internal combustion engine.

[0020] The internal combustion engine 01 is mounted on the vehicle so that the crankshaft is oriented horizontally relative to the longitudinal direction of the vehicle body, and a crank gear (not shown) is fixed to a portion of the crankshaft in the axial direction. The crank gear is an engine-side gear for driving a balancer device 10, which will be described later.

[0021] Furthermore, an oil pan 05 that stores lubricating oil therein is attached to the bottom of the cylinder block 04, and a balancer device 10 for suppressing secondary vibrations of the internal combustion engine 01 is housed inside this oil pan 05. The oil pan 05 is provided on the opposite side (ground side) of the internal combustion engine, and stores lubricating oil for lubricating the sliding parts of the internal combustion engine.

[0022] The balancer device 10, details of which will be described later, has an upper housing, a lower housing, a balancer body, and an oil pump 11. The upper housing and the lower housing are fixed to the underside of the cylinder block 04 by a plurality of balancer fixing bolts 06 in a state in which they overlap vertically as viewed in the direction of gravity. In addition, the oil pump 11 is connected to and integrated with the balancer device 10 by a plurality of oil pump fixing bolts 07. The oil pump 11 is a variable displacement oil pump that changes the amount of volume change in a pump chamber in accordance with a specified operating state.

[0023] The variable displacement oil pump used in this embodiment is a vane pump having a mechanism for reducing the amount of change in the volume of the pump chamber when the pump rotates at high speed, and is, for example, a known one as described in JP 2011-111926 A. The oil pump 11 is fixed to the front side of the upper housing by a plurality of oil pump fixing bolts 07.

[0024] 1, the balancer device 10 is disposed in an oil pan 05 below the internal combustion engine, and therefore in the conventional balancer device 10, there is a phenomenon in which lubricating oil dropping from the internal combustion engine 01 located above the balancer device 10 falls on the balancer drive gear and the pump drive gear disposed adjacent thereto. If more lubricating oil than necessary falls on the pump drive gear that drives the oil pump to rotate, the rotational resistance due to the viscosity of the lubricating oil increases at the meshing portion of the reduction gear. Since the viscosity of the lubricating oil is high particularly at low temperatures, this resistance cannot be ignored from the viewpoint of fuel economy, etc.

[0025] In addition, the pump drive gear stirs the lubricating oil, causing it to splash out from the open part of the upper housing, and the lubricating oil is stirred up toward the top of the engine, resulting in increased oil consumption.

[0026] Therefore, this embodiment proposes a balancer device that can suppress an increase in rotational resistance at the meshing portion between the reduction gear and the pump drive gear by minimizing the amount of lubricating oil that falls on the pump drive gear that rotates and drives the oil pump 11, and also suppresses the scattering of lubricating oil from the open portion of the upper housing by stirring the lubricating oil with the pump drive gear, thereby suppressing an increase in oil consumption caused by the lubricating oil being swept up above the engine. The balancer device for an internal combustion engine according to this embodiment will be described below.

[0027] A representative embodiment of the present invention will be described in detail with reference to Fig. 2 to Fig. 7. Fig. 2 shows the external appearance of the balancer device 10 viewed from diagonally above, with the front side of the drawing being the front side (front side) of the vehicle and the back side of the drawing being the rear side (rear side) of the vehicle. Fig. 3 shows the balancer device 10 viewed from the internal combustion engine side (top side), and Fig. 4 shows the balancer device 10 viewed from the oil pan side (bottom side). The balancer device 10 is fixed to a cylinder block 04 as shown in Fig. 1.

[0028] 2 to 4, an oil pump 11 is fixed to the front side of the balancer device 10, and a pump body (not shown) is rotationally driven by a second balancer shaft (not shown) built into the balancer device 10. When attached to an internal combustion engine, the balancer device 10 includes a lower housing 12 located on the lower side as viewed in the direction of gravity, and an upper housing 13 located above the lower housing.

[0029] The balancer body is housed in the storage space formed by these two housings 12, 13. The upper housing 13 is formed with a fixing portion 14 for fixing the balancer device 10 to the cylinder block 04 by a balancer fixing bolt 06 (see FIG. 1).

[0030] The oil pump 11 provided on the front side is fixed to the end face of the upper housing 13 by a pump flange 15 and an oil pump fixing bolt 07. The face of the pump flange 15 opposite the balancer device 10 is covered by a pump cover 16 that houses a pump body (not shown). A cover flange 17 of the pump cover 16 is fixed to the pump flange 15 by a flange fixing bolt 18. In this way, the pump flange 15 and the pump cover 16 are integrated together. The pump flange 15 and the pump cover 16 can also be manufactured as a single unit by casting or pressing.

[0031] A balancer drive gear 19 is exposed on the side of the balancer device 10 opposite the oil pump 11, and this balancer drive gear 19 meshes with an engine-side gear rotated by the crankshaft to form a rotation transmission system that rotates the balancer body. The balancer drive gear 19 is housed in the lower housing 12, and is exposed from an upper opening 20 formed in the upper housing 13, so as to mesh with the engine-side gear.

[0032] A first gear 22 fixed to a first balancer shaft 21 (see FIG. 3) is disposed inside the balancer drive gear 19, and a second gear 24 fixed to a second balancer shaft 23 (see FIG. 3) is disposed adjacent thereto, and rotation is transmitted from the first gear 22 to the second gear 24. Well-known balance weights are provided on the first balancer shaft 21 and the second balancer shaft 23. The configuration of the balance weights is shown in FIG. 5.

[0033] In the conventional configuration, the balancer drive gear 19 was disposed on the side of the oil pump 11, but in this embodiment, since it is disposed on the side opposite to the oil pump 11, there is no need to provide the upper opening 20 for exposing the balancer drive gear 19 in the upper housing 13 on the oil pump 11 side. Therefore, as will be described later, it is possible to configure the upper housing 13 so that an end face 25 on the oil pump 11 side and an end face 26 of the pump flange 15 on the balancer device 10 side are in close contact with each other.

[0034] Although details will be described later, the gear storage space (see Figure 6) formed by the end face 25 on the oil pump 11 side of the upper housing 13 and the end face 26 on the balancer device 10 side of the pump flange 15 houses a pump drive gear (not shown) that drives the oil pump 11, and a reduction gear (not shown) fixed to the second balancer shaft 23 that drives this pump drive gear.

[0035] Therefore, since the end face 25 of the upper housing 13 on the oil pump 11 side and the end face 26 of the pump flange 15 on the balancer device 10 side are closely attached to each other, the end face 25 of the upper housing 13 on the oil pump 11 side has a so-called "roof function," and the lubricating oil falling from the internal combustion engine side can be prevented from flowing toward the pump drive gear or the reduction gear.

[0036] In Fig. 4, the lower housing 12 is fixed to the upper housing 13 by housing fixing bolts 27. Furthermore, a rectangular oil drain hole 30 having a width (W) and length (L) for draining lubricating oil is formed between an end face 28 of the lower housing 12 on the oil pump 11 side and an end face 29 of the pump flange 15 on the balancer device 10 side. Here, the end face 26 of the pump flange 15 shown in Fig. 3 and the end face 29 of the pump flange 15 shown in Fig. 4 are actually the same planar area facing the balancer device 10 of the pump flange 15.

[0037] This oil drain hole 30 is formed by a recess formed by cutting out the end face portion 28 of the lower housing 12 on the oil pump 11 side, on the side opposite to the oil pump 11. By providing a cutout for forming the oil drain hole 30 in the lower housing 12 in this way, the oil drain hole 30 can be formed simply by cutting out the end face of the lower housing 12, which is advantageous in terms of manufacturing.

[0038] It also functions to return the lubricating oil that accumulates in the gear storage space defined by end face 25 on the oil pump 11 side of the upper housing 13 and end face 26 on the balancer device 10 side of the pump flange 15, in which the pump drive gear and reduction gear are housed, and in the gear storage space defined by end face 28 on the oil pump 11 side of the lower housing 12 and end face 29 on the balancer device 10 side of the pump flange 15, to the oil pan.

[0039] Furthermore, in this embodiment, the oil pump 11 is fixed to the upper housing 13 via the pump flange 15 by the oil pump fixing bolts 07. On the other hand, it is not fixed to the lower housing 12. If the oil pump 11 were also to be assembled to the lower housing 12, the influence of assembly errors between the upper housing 13 and the lower housing 12 could not be eliminated, but if it were fixed only to the upper housing 13, the positional accuracy of the discharge hole, fastening screw holes, seal surface, etc. of the oil pump 11 when assembled can be improved. Note that if such influences can be eliminated, the oil pump 11 may also be assembled to the lower housing 12.

[0040] Next, the internal configuration of the balancer device 10 will be described with reference to Fig. 5. Fig. 5 shows a state in which the upper housing 13 shown in Fig. 2 has been removed.

[0041] The balancer body is composed of a first rotating system having a balance weight and a second rotating system also having a balance weight, and the rotation of the first rotating system is reversed by a gear transmission mechanism to rotate the second rotating system. By rotating the first rotating system and the second rotating system, a vibratory force is generated, which is in the opposite phase to the secondary component of the vibratory force of the internal combustion engine caused by the reciprocating motion of the pistons, thereby reducing the vibration of the internal combustion engine. These configurations are well known.

[0042] The first rotating system is made up of a balancer drive gear 19 fixed to the first balancer shaft 21, a first gear 22, a front-side first bearing 31 and a rear-side first bearing 32 which support the first balancer shaft 21, and a first balance weight 33 provided on the first balancer shaft 21. The front-side first bearing 31 and the rear-side first bearing 32 are fixed and supported between the lower housing 12 and the upper housing 13, thereby rotating and supporting the first balancer shaft 21. A circular first thrust receiving portion 34 is disposed on the oil pump 11 side of the first balancer shaft 21.

[0043] On the other hand, the second rotating system is made up of a reduction gear 35 fixed to both ends of the second balancer shaft 23, the second gear 24, a front-side second bearing 36 and a rear-side second bearing 37 which support the second balancer shaft 23, and a second balance weight 38 provided on the second balancer shaft 23. Here, the reduction gear 35 is engaged with a pump drive gear 39 which is connected to the rotating shaft of the oil pump 11, and rotates the pump drive gear 39.

[0044] Additionally, the front-side second bearing 36 and the rear-side second bearing 37 are fixed and supported between the lower-side housing 12 and the upper-side housing 13, thereby rotating and supporting the second balancer shaft 23. A circular second thrust receiving portion 40 is disposed on the oil pump 11 side of the second balancer shaft 23.

[0045] When an engine-side gear fixed to a crankshaft disposed above the balancer device 10 rotates, the balancer drive gear 19 rotates at twice the rotation speed of the engine-side gear, and the first balancer shaft 21 to which the balancer drive gear 19 is fixed also rotates. In addition, the second gear 24 meshed with the first gear 22 fixed to the first balancer shaft 21 rotates, causing the second balancer shaft 23, the phase of which is adjusted with that of the first balancer shaft 21, to rotate, generating a balancer vibrating force. This balancer device 10 generates a vibrating force in the opposite phase to the secondary component of the vibrating force of the internal combustion engine caused by the reciprocating motion of the pistons, thereby reducing the vibration of the internal combustion engine.

[0046] In this manner, the balancer drive gear 19 is fixed to the end of the first balancer shaft 21 opposite to the oil pump 11, and the first gear 22 is fixed inside the balancer drive gear 19. The first balancer shaft 21 is journaled by the front-side first bearing 31 and the rear-side first bearing 32. In addition, a first balance weight 33 is provided on the first balancer shaft 21 between the front-side first bearing 31 and the rear-side first bearing 32.

[0047] Similarly, a second gear 24 and a reduction gear 35 are fixed to both ends of a second balancer shaft 23 disposed in parallel to the first balancer shaft 21, and the second balancer shaft 23 is journaled by a front-side second bearing 35 and a rear-side second bearing 36. A second balance weight 37 is provided on the second balancer shaft 24 between the front-side second bearing 35 and the rear-side second bearing 36. The second gear 24 is rotated by the first gear 22, which rotates the second balancer shaft 23, which in turn rotates the reduction gear 35.

[0048] A pump drive gear 39 fixed to the rotating shaft of the oil pump 11 is provided between the oil pump 11 and the first front bearing 31 that supports the first balancer shaft 21, and this pump drive gear 39 is meshed with the reduction gear 35. The gear housing space in which the pump drive gear 39 and the reduction gear 35 are located is connected to the oil drain hole 30, so that unnecessary lubricating oil in this gear housing space is drained from the oil drain hole 30 to the oil pan.

[0049] 2, the balancer drive gear 19, the first gear 22, and the second gear 24 are housed in the lower housing 12, and are exposed from an upper opening 20 formed in the upper housing 13. On the other hand, the reduction gear 35 and the pump drive gear 39 are rotatably housed in a gear housing space between the end faces 25, 28 of the lower housing 12 and the upper housing 13 facing the pump flange 15, and are covered by the end faces 25, 28 of the lower housing 12 and the upper housing 13.

[0050] Therefore, the lubricating oil falling from the internal combustion engine side is blocked, particularly by the end face portion 25 of the upper housing 13, and the lubricating oil is prevented from entering the gear storage space in which the reduction gear 35 and the pump drive gear 39 are stored.

[0051] In addition, the gear storage space in which the reduction gear 35 and the pump drive gear 39 are housed is drained through the oil drain hole 30 formed between the end face 28 of the lower housing 12 and the end face 29 of the pump flange 15, so excess lubricating oil is not accumulated in the gear storage space in which the reduction gear 35 and the pump drive gear 39 are housed.

[0052] This prevents the lubricating oil dropping from the internal combustion engine 01 located above the balancer device 10 from falling on the balancer drive gear and the pump drive gear located nearby, thereby solving the problem of increased rotational resistance due to the viscosity of the lubricating oil. Also, since there is no open part in the upper housing 13, the lubricating oil is not stirred by the pump drive gear, causing it to splash, solving the problem of increased oil consumption.

[0053] Next, the configuration of the gear storage space formed by the end face portion 25 on the oil pump 11 side of the upper housing 13 and the end face portion 26 on the balancer device 10 side of the pump flange 15, and the configuration of the gear storage space formed by the end face portion 28 on the oil pump 11 side of the lower housing 12 and the end face portion 29 on the balancer device 10 side of the pump flange 15 will be described.

[0054] Fig. 6 shows a side view of the pump flange 15 to which the oil pump 11 is fixed, as viewed from the oil pump side in the axial direction of the balance shafts 21, 24, with the pump flange 15, to which the oil pump 11 is fixed, removed from the upper housing 13. Similarly, Fig. 7 shows the external appearance as viewed obliquely from above in this state.

[0055] 6 and 7, an end face portion 25 of the upper housing 13 is formed on a side surface (SS; the surface to which the pump flange 15 is attached) of the upper housing 13 that is perpendicular to the axial direction of the balance shafts 21, 23. This end face portion 25 forms a gear storage space 41 in which the pump drive gear 39 and the reduction gear 35 are stored. The end face portion 25 is formed to cover the pump drive gear 39 and the reduction gear 35 from above, and to extend to the vicinity of a joining surface 42 between the upper housing 13 and the lower housing 12.

[0056] The length of the end face portion 25 in the axial direction of the balancer shafts 21, 23 is determined to be longer than the axial thickness of the pump drive gear 39 and the reduction gear 35 in order to accommodate the pump drive gear 39 and the reduction gear 35, and is set to a length that contacts the flat area of ​​the end face portion 26 of the pump flange 15 attached to the pump fixing portion described below. Therefore, the contact portions of the both end face portions 25, 26 are in a contact form that makes it difficult for lubricating oil to penetrate.

[0057] Hereinafter, this end face portion 25 will be described as the “upper-side protruding partition wall portion 25.” In addition, this upper-side protruding partition wall portion 25 is formed in a plate shape that protrudes toward the oil pump 11 in the axial direction of the balancer shafts 21, 23.

[0058] The peripheral shape of this upper-side protruding partition portion 25 is shaped to match the shapes of the pump drive gear 39 and reduction gear 35 that are housed therein. Furthermore, the upper-side protruding partition portion 25 is formed with a pair of upper reinforcing protruding partition portion 43U and lower reinforcing protruding partition portion 43B that extend in a direction away from the gear housing space 41. These reinforcing protruding partition portions 43U and 43B extend to the pump fixing portion 44 and have a reinforcing function to prevent deformation of the upper-side protruding partition portion 25. The pump fixing portion 44 is a fixing surface to which the pump flange 15 is fixed.

[0059] An oil outflow passage 45 is formed in the spatial region surrounded by the reinforcing protruding partition wall portions 43U, 43B and the upper side protruding partition wall portion 25. The oil outflow passage 45 is formed by utilizing the space existing between the upper side protruding partition wall portion 25 and the pump fixing portion 44.

[0060] Further, an upper oil outflow hole 46U and a lower oil outflow hole 46B are formed in each of the reinforcing protruding partitions 43U, 43B, and the lower oil outflow hole 46B is formed at a position farther outward than the upper oil outflow hole 46U when viewed from the first balancer shaft 21. Moreover, the balancer device 10 is actually mounted to the internal combustion engine in such a manner that the lower oil outflow hole 46B is on the lower side in the direction of gravity. This allows the lubricating oil to flow smoothly.

[0061] The lubricating oil dropping from the internal combustion engine flows along the outside of the upper protruding partition wall portion 25, flows into the oil outflow passage 45 from the upper oil outflow hole 46U, passes through the oil outflow passage 45, and flows out from the lower oil outflow hole 46B, and is returned to the oil pan. In this way, the lubricating oil is smoothly returned to the oil pan, so that a shortage of circulating lubricating oil can be suppressed.

[0062] A pump flange 15 is attached to the pump fixing portion 44, and the oil pump 11 is fixed by a pump fixing bolt 07. The thickness of the upper side protruding partition portion 25 is formed thinner than the thickness of the pump fixing portion 44. This reduces the weight of the upper side protruding partition portion 25 and increases the strength of the pump fixing portion 44. Since making the upper side protruding partition portion 25 thinner reduces its strength, its strength is reinforced by the reinforcing protruding partition portions 43U and 43B.

[0063] Meanwhile, an end face portion 28 of the lower housing 12 is formed on a side surface (SS) of the lower housing 12 perpendicular to the axial direction of the balance shafts 21, 23. This end face portion 28 forms a gear storage space 41 in which the pump drive gear 39 and the reduction gear 35 are stored. The end face portion 28 is formed to cover the pump drive gear 39 and the reduction gear 35 from below, and to extend to the vicinity of a joining surface 42 between the upper housing 13 and the lower housing 12.

[0064] The length of the end face portion 28 in the axial direction of the balance shafts 21, 23 is set to a length for accommodating the pump drive gear 39 and the reduction gear 35. However, as described above, the length is shorter than the end face portion 25 of the upper housing 13 in order to form the oil drain hole 30. Hereinafter, this end face portion 28 will be described as the "lower side protruding partition wall portion 28." In addition, this lower side protruding partition wall portion 28 is formed in a plate shape that protrudes toward the oil pump 11 in the axial direction of the balancer shafts 21, 23.

[0065] The peripheral shape of this lower-side protruding partition wall portion 28 is shaped to match the shapes of the pump drive gear 39 and reduction gear 35 housed therein. An oil drain hole 30 is formed on the lower side in the direction of gravity between the lower-side protruding partition wall portion 28 and the end face portion 29 of the pump flange 15 so that the lubricating oil can be discharged. The lubricating oil present in the gear housing space 41 flows out from the oil drain hole 30 and is returned to the oil pan. In this way, the lubricating oil is smoothly returned to the oil pan, so that a shortage of circulating lubricating oil can be suppressed.

[0066] 5 and 6, the reduction gear 35 is formed with a smaller diameter than the circular second thrust receiving portion 40 provided between the second balance weight 38 and the reduction gear 35, and the pump drive gear 39 is formed with a larger diameter than the circular first thrust receiving portion 34 provided between the first balance weight 33 and the pump drive gear 39. By adopting such a configuration, the pump drive gear 39 and the reduction gear 35 can be lubricated with a small amount of lubricating oil from the thrust receiving portion 34 of the first balance shaft 21, and the reduction gear 35 is not unnecessarily sprayed with lubricating oil.

[0067] 6 and 7, a pair of positioning pins 47L, 47R are provided on the mounting surface for the oil pump 11, which is the side surface SS of the upper housing 13, so as to sandwich the first balancer shaft 21 and the second balancer shaft 23. The positioning pins 47L, 47R enable the positioning of the pump flange 15, and as a result, the mounting accuracy of the oil pump 11 can be improved.

[0068] 6 and 7, a space 48L having a predetermined shape is provided between the bolt fixing portion 44 on the left side and the gear housing space 41, forming an oil outflow passage 45. This space 48L serves to reduce the weight of the upper housing 13, to share the oil outflow passage 45, and to suppress the propagation of vibrations caused by the operation of the oil pump 11. In addition, a space 48R having a predetermined shape is provided in the bolt fixing portion 44 on the right side in FIG. 6 and 7. This space 48R serves to reduce the weight of the upper housing 13, and to suppress the propagation of vibrations caused by the operation of the oil pump 11.

[0069] Returning to Fig. 5, the reduction gear 35 and the pump drive gear 39 are composed of helical gears. The twist angles of these helical gears are preferably set to an angle that enhances the movement of the lubricating oil toward the oil drain hole 30 by the rotation of the reduction gear 35 and the pump drive gear 39. This enables the lubricating oil to be smoothly discharged into the oil pan.

[0070] In addition, the twist angle of the helical gear constituting the reduction gear 35 and the pump drive gear 39 is preferably set to an angle that generates a thrust force that biases the pump drive gear 39 towards the oil pump 11. This increases the gap between the first thrust receiving portion 34, making the flow of lubricating oil in the gear accommodating space 41 smoother and facilitating the discharge of the lubricating oil.

[0071] In the above-described embodiment, a two-shaft balancer device having a first balancer shaft and a second balancer shaft is disclosed, but the present invention can also be applied to a single-shaft balancer device using only the first balancer shaft.

[0072] As described above, the present invention is characterized in that it comprises an upper housing attached to an internal combustion engine, a lower housing fixed to the underside of the upper housing, a balancer body housed in a space formed between the upper housing and the lower housing, and an oil pump fixed to at least the upper housing, wherein the end face of the upper housing and the end face of the oil pump are attached in a form in which they contact each other, and the end face of the lower housing and the end face of the oil pump are attached in a form in which they have a predetermined gap between them.

[0073] This reduces as much as possible the amount of lubricating oil that falls on the pump drive gear that rotates the oil pump, thereby suppressing an increase in rotational resistance at the meshing portion between the reduction gear and the pump drive gear.In addition, by stirring the lubricating oil by the pump drive gear, it is possible to suppress the scattering of lubricating oil from the open part of the upper housing, and to suppress an increase in the consumption of lubricating oil due to the lubricating oil being swirled up above the engine.

[0074] The present invention is not limited to the above-described embodiment, but includes various modifications. For example, the above-mentioned embodiments have been described in detail to clearly explain the present invention, and are not necessarily limited to those including all of the configurations described. Also, it is possible to replace a part of the configuration of one embodiment with the configuration of another embodiment, and it is also possible to add the configuration of another embodiment to the configuration of one embodiment. Also, it is possible to add, delete, or replace a part of the configuration of each embodiment with another configuration. [Explanation of symbols]

[0075] 07...Oil pump fixing bolt, 10...Balancer device, 11...Oil pump, 12...Lower housing, 13...Upper housing, 15...Pump flange, 19...Balancer drive gear, 21...First balancer shaft, 22...First gear, 23...Second balancer shaft, 24...Second gear, 33...First balance weight, 30...Oil drain hole, 31...First front bearing, 32...First rear bearing, 34...Reduction gear, 35...Second front bearing, 36...Second rear bearing, 37...Second balance weight, 38...Pump drive gear.

Claims

1. A first balancer shaft having a balancer drive gear at one end which meshes with an engine side gear rotated by an internal combustion engine, and a first gear fixed thereto and having a first balance weight disposed adjacent to the first gear; a second balancer shaft having a second gear fixed to one end thereof and a reduction gear fixed to the other end thereof, the reduction gear being adapted to mesh with a pump drive gear of an oil pump, and a second balance weight provided between the second gear and the reduction gear; a lower housing on which the balancer drive gear, the first gear, the first balancer shaft including the first balance weight, the second gear, the second balancer shaft including the second balance weight, and the reduction gear are mounted; an upper housing disposed above the lower housing when viewed in the direction of gravity, the upper housing being formed in a shape that covers from above the first balancer shaft including the first balance weight, the second balancer shaft including the second balance weight, the reduction gear, and the pump drive gear, and the upper housing is assembled to the lower housing; In a state where the pump drive gear is engaged with the reduction gear and the oil pump is assembled, an end surface portion of the upper housing and an end surface portion of the oil pump are attached in contact with each other so as to cover the pump drive gear and the reduction gear from above, an end surface of the lower housing and an end surface of the oil pump are attached in such a manner that a predetermined gap is formed between them to allow lubricating oil to be discharged from a space in which the pump drive gear and the reduction gear are disposed, the oil pump is fixed only by a pump fixing portion formed on an end surface portion of the upper housing, a gear receiving space for receiving the reduction gear and the pump drive gear is formed in an end surface of the upper housing and an end surface of the lower housing; the gear accommodating space is defined by an upper-side protruding partition wall portion formed on an end surface of the upper housing and a lower-side protruding partition wall portion formed on an end surface of the lower housing, the protruding partition wall portions being plate-shaped; An oil outflow passage is formed along the outer periphery of the upper protruding partition wall, Between the upper-side protruding partition wall portion and the pump fixing portion, an upper-side reinforcing protruding partition wall portion connected to an upper side of the upper-side protruding partition wall portion and a lower-side reinforcing protruding partition wall portion connected to a lower side of the upper-side protruding partition wall portion are formed, The upper reinforcing protruding partition wall portion is formed with an upper oil outflow hole connecting an outside of the upper protruding partition wall portion and the oil outflow passage, and the lower reinforcing protruding partition wall portion is formed with a lower oil outflow hole connecting an outside of the lower protruding partition wall portion and the oil outflow passage. A balancer device for an internal combustion engine, comprising:

2. The balancer device for an internal combustion engine according to claim 1, The balancer drive gear fixed to the first balancer shaft is rotated by meshing with the engine side gear rotated by the crankshaft of the internal combustion engine. A balancer device for an internal combustion engine, comprising:

3. The balancer device for an internal combustion engine according to claim 1, The gear storage space is defined by an end surface of the oil pump disposed to face the upper and lower protruding partition walls. A balancer device for an internal combustion engine, comprising:

4. The balancer device for an internal combustion engine according to claim 3, The upper and lower protruding partitions extend to the vicinity of the joining surfaces of the upper and lower housings, and the peripheral shapes thereof are formed to match the shapes of the reduction gear and the pump drive gear. A balancer device for an internal combustion engine, comprising:

5. The balancer device for an internal combustion engine according to claim 1, The lower oil outlet hole is formed at a position farther from the first balancer shaft than the upper oil outlet hole. A balancer device for an internal combustion engine, comprising:

6. The balancer device for an internal combustion engine according to claim 1, The thickness of the upper protruding partition wall is formed to be thinner than the thickness of the pump fixing portion. A balancer device for an internal combustion engine, comprising:

7. The balancer device for an internal combustion engine according to claim 1, The pump drive gear and the reduction gear are helical gears, and the helical gears have helical angles set to angles that enhance the action of the lubricating oil moving toward the gap when the pump drive gear and the reduction gear are rotated. A balancer device for an internal combustion engine, comprising:

8. The balancer device for an internal combustion engine according to claim 1, The pump drive gear and the reduction gear are helical gears, and the helix angle of the pump drive gear is set so that the pump drive gear generates a thrust force toward the oil pump. A balancer device for an internal combustion engine, comprising:

9. The balancer device for an internal combustion engine according to claim 1, The gap is formed by a notch formed in the lower housing so as to be away from an end face of the oil pump. A balancer device for an internal combustion engine, comprising:

10. The balancer device for an internal combustion engine according to claim 1, the reduction gear is formed to have a smaller diameter than a second thrust receiving portion provided between the second balance weight and the reduction gear, The pump drive gear is formed to have a larger diameter than a first thrust receiving portion provided between the first balance weight and the pump drive gear. A balancer device for an internal combustion engine, comprising:

11. The balancer device for an internal combustion engine according to claim 1, A pair of positioning pins are provided on the mounting surface of the upper housing to which the oil pump is attached, for determining the position of the end surface of the oil pump. A balancer device for an internal combustion engine, comprising:

12. The balancer device for an internal combustion engine according to claim 1, A space of a predetermined shape is formed between the pump fixing portion of the end face portion of the upper housing and the upper protruding partition wall portion. A balancer device for an internal combustion engine, comprising:

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