JP6140020B2 - Balancer device for internal combustion engine - Google Patents

Description

  The present invention relates to a balancer device that reduces secondary vibration of an internal combustion engine.

  As a conventional balancer device for an internal combustion engine, there is one described in Patent Document 1 below. In brief, the housing is housed and supported in an oil pan while being attached to the lower part of the crankcase of the engine, and a pair of sliding bearings provided at predetermined intervals in the axial direction of the housing. Rotational force is transmitted from the drive-side balancer shaft by a drive-side balancer shaft that is rotatably accommodated by a drive-side balancer shaft to which the rotational force is transmitted from the crankshaft and a pair of sliding bearings similarly provided at predetermined intervals in the axial direction of the housing. A driven-side balancer shaft.

  The drive-side balancer shaft is formed with two journal parts that are respectively supported by the two front and rear sliding bearings, and a first counterweight is integrally provided between the front and rear journals, and the rear journal A first counterweight is integrally provided on the rear side.

  The driven balancer shaft is also provided with two front and rear journals, and a first counterweight is integrally provided between the two journals, and a second counterweight is integrated on the rear side of the rear journal. Is provided.

  Then, when the crankshaft is rotationally driven by the engine start, the drive-side balancer shaft is rotationally driven at a rotational speed twice that of the crankshaft via a drive chain or the like, and the driven gear meshes with the drive-side gear as it rotates. The side gear rotates in the opposite direction to drive the driven balancer shaft in the opposite direction to the drive side balancer shaft. Thereby, secondary vibration of the internal combustion engine is effectively suppressed by rotation of each counterweight.

JP 2008-14351 A

  By the way, in the balancer device, the first and second counterweights are synchronously rotated by the rotation of the drive side balancer shaft and the driven side balancer shaft, but due to the mass of each counterweight, The surface pressure distribution with respect to the bearing surface of each sliding bearing on the outer peripheral surface is different in the axial direction.

  For example, the bearing surface of the two slide bearings on the front and rear of the first counterweight receives the pressure received from each journal on the entire bearing surface of the front slide bearing, but the bearing on the rear slide bearing on the second counterweight side. On the surface, the surface pressure at the rear portion on the second counterweight side is increased, whereas the surface pressure at the front portion on the first counterweight side is decreased.

  However, in the balancer device, the axial length of each journal that slides on the bearing surface of each sliding bearing is set to the same length in both the front and rear, so that the entire contact area increases. As a result, the sliding resistance (friction) between each journal and each bearing surface increases, which may increase the driving load of the balancer device.

  An object of the present invention is to provide a balancer device for an internal combustion engine that can reduce the overall friction by reducing the contact area of a portion having a small surface pressure between a bearing and a journal.

  The invention according to claim 1 is, in particular, the contact area of the journal surface located between the first and second counterweights of the balancer shaft with the bearing surface on the first counterweight side, It is characterized by being formed smaller than the contact area with the bearing surface on the second counterweight side.

  According to this invention, since the contact area of the portion where the surface pressure between the bearing and the journal surface is small is formed small, the overall friction can be reduced.

The cross section of the balancer apparatus which concerns on this invention is shown, A is AA sectional view taken on the line of FIG. 3, B is BB sectional drawing of FIG. It is a perspective view which shows the partial cross section of the drive side balancer shaft provided to this embodiment. It is a top view which shows the balancer apparatus which removed the upper housing in this embodiment. It is a partial cross section figure which shows the attachment state to the internal combustion engine of the balancer apparatus of this embodiment. It is a longitudinal cross-sectional view of the balancer apparatus which shows 2nd Embodiment. It is a longitudinal cross-sectional view of the balancer apparatus which shows 3rd Embodiment. It is a longitudinal cross-sectional view of the balancer apparatus which shows 4th Embodiment. It is a longitudinal cross-sectional view of the balancer apparatus which shows 5th Embodiment.

Hereinafter, an embodiment in which a balancer device according to the present invention is applied to, for example, an in-line four-cylinder internal combustion engine of an automobile will be described based on the drawings.
[First Embodiment]
As shown in FIG. 4, a ladder frame 4 made of an aluminum alloy material having a bearing portion that pivotally supports the crankshaft 3 is fixed to the lower part of the cylinder block 2 of the internal combustion engine 1. A vertically divided oil pan 5 having engine oil stored therein is attached to the lower part.

  The crankshaft 3 is rotatably supported by a plurality of bearings composed of bearing caps and the like that are coupled to the lower portion of the cylinder block 2 by bearing bolts (not shown), and has a shaft end portion 3a that is integrally provided on the front end side. A large-diameter crank sprocket 6 is attached.

  The crank sprocket 6 is coupled to the shaft end portion 3a of the crankshaft 3 by shrink fitting through an insertion hole 6a formed in the center portion, and has a gear tooth portion 6b on the outer periphery.

  In a space surrounded by the lower part of the cylinder block 2 and the ladder frame 4 and the oil pan 5, a balancer device 7 for suppressing secondary vibration of the engine is accommodated.

  As shown in FIGS. 1, 3 and 4, the balancer device 7 includes a housing 8 fixed to the lower surface of the ladder frame 4, and is rotatably supported in the housing 8 so as to be parallel to the engine longitudinal direction. The drive-side balancer shaft 9 and the driven-side balancer shaft 10 disposed in the center, and the helical-type drive-side gear 11 that is provided on substantially the center side of each of the balancer shafts 9 and 10 and in which the respective tooth portions mesh with each other. And a driven gear 12.

  The housing 8 is formed of an aluminum alloy material as a whole, and includes a lower housing 13 on the oil pan 5 side and an upper housing 14 disposed on the upper portion of the lower housing 13. The plurality of bolts 15 are fastened and fixed from above and below.

  The lower housing 13 and the upper housing 14 are formed in a narrow rectangular portion and a widened portion having a planar rectangular shape, and frame-shaped deck portions 13a and 14a having a predetermined width are formed on the outer peripheral portions of the mating portions facing each other from above and below. In addition, a pair of front and rear parallel first and second transverse beam deck portions 13b, 14b, 13c, and 14c, which are bearing projections coupled to the widened portion so as to cross the frame-shaped deck portions 13a and 14a, are integrally formed. Is formed.

  Five boss portions 13g, 14g for forming through holes for inserting bolts 40 out of bolts for attaching and fixing the housing 8 to the ladder frame 4 at predetermined positions on the outer peripheral side of the frame deck portions 13a, 14a. Are integrally formed, and one boss portion 14 i for forming an insertion hole through which the bolt 41 is inserted is formed on the upper housing 14 side.

  On the front end side of the narrow portion of each of the housings 13 and 14 is a short third transverse beam deck that is parallel to the transverse beam deck portions 13b, 14b, 13c, and 14c and coupled to the frame-shaped deck portions 13a and 14a. The parts 13d and 14d are integrally formed.

  The first to third transverse beam deck portions 13b, 14b, 13c, 14c, 13d, and 14d have eight small-diameter bolt insertion holes 13h and 14h through which the bolts 15 that connect the housings 13 and 14 are inserted. Is formed.

  As shown in FIGS. 1A, 3 and 4, the drive-side balancer shaft 9 is fixed to a front end portion of a tip shaft 9c by a fixing bolt 16 in which a balancer sprocket 17 is screwed from the axial direction. The rotational force from the crankshaft 3 is transmitted via a drive chain 18 wound between the balancer sprocket 17 and the crank sprocket 6. As a result, the balancer shafts 9 and 10 are rotated in opposite directions via the drive side gear 11 and the driven side gear 12. The shafts 9 and 10 are set to rotate twice per rotation of the crankshaft 3.

  As shown in FIGS. 1A to 3, the drive-side balancer shaft 9 is formed with three cylindrical journal surfaces 9 a, 9 b, and 9 c on the front end side, the center portion, and the rear end side in the axial direction. The three journal surfaces 9a to 9c on the center side, the rear end side, and the front end side are respectively formed at positions facing the first to third transverse beam deck portions 13b to 14d of the lower housing 13 and the upper housing 14, respectively. Three semicircular arc-shaped first to third bearing grooves 19a, 19b, 20a, 20b, 21a, 21b are rotatably supported via three plain bearings 22, 23, 24 as bearings.

  Two semicircular first and second counterweights 25 and 26 are integrally provided at the symmetrical positions before and after the rear journal surface 9b of the drive side balancer shaft 9 is sandwiched. The counterweights 25 and 26 have substantially the same shape and the same weight, but their circumferential positions are shifted from each other by a predetermined angle.

  The drive-side gear 11 is fixed to the drive-side balancer shaft 9 by press-fitting or the like, and as shown in FIG. 5, the drive-side gear 11 is sandwiched between opposing thrust walls 13e and 13f of the lower housing 13 to move in the axial direction. Being regulated.

  The two journal surfaces 9c and 9a on the front end side and the center side have substantially the same outer diameter, but the rear end side journal provided between the first counterweight 25 and the second counterweight 26. The surface 9b is formed to have an outer diameter slightly larger than that of the front end side and the center side, and a part of the first counterweight 25 side is notched so as to be larger than the area of the center side journal surface 9a. It is formed small.

  That is, as shown in FIGS. 1A and 2, the rear end side journal surface 9b has a notch 9d formed in about 2/3 of the circumferential direction on the first counterweight 25 side. The contact area between the remaining surface 9e remaining in the circumferential direction and the sliding surface 23b of the rear end side plain bearing 23 is a cylinder remaining on the second counterweight 26 side of the journal surface 9b with respect to the notch 9d. The journal surface 9b is formed smaller than the contact area between the sliding surface 23b of the rear end side plain bearing 23.

  The remaining surface 9e in the circumferential direction in which the notch 9d is formed has a small contact surface pressure with the sliding surface 23b of the plain bearing 23 as described in the additional drawing on the lower side of FIG. 1A. It is a part. In other words, the second counterweight 26 in the state where the rear end side is free is supported in a cantilevered state by one plain bearing 23 and the rear end side journal surface 9b. Although a large surface pressure acts on the rear end portion near the counterweight 26, the surface pressure is smaller than that on the rear end portion because the front end portion near the first counterweight 25 is supported in a dual-supported state. .

  Therefore, in this embodiment, the notch 9d of about 2/3 in the circumferential direction is formed on the front end side of the journal surface 9b where the surface pressure is reduced, and the circle remaining in the circumferential direction of the notch 9d is left. The contact area between the arc-shaped residual surface 9e and the sliding surface 23b of the plain bearing 23 is reduced.

  Thus, as shown in FIGS. 1A and 2, the residual surface 9e is formed to have an area of about 1/3 in the circumferential direction. The residual surface 9e causes the journal surface 9b and the plain bearing 23 to be By ensuring a small contact area with the sliding surface 23b, the radial balance of the drive-side balancer shaft 9 due to the mass of the second counterweight 25 is suppressed, and as described later, The effect of reducing friction can be obtained.

  On the other hand, as shown in FIGS. 3 and 4, the driven-side balancer shaft 10 has an axial length shorter than that of the driving-side balancer shaft 9 and is formed at two axial front and rear ends. Surfaces 10a and 10b are provided as bearings in two semicircular arc-shaped fourth and fifth bearing grooves 27a, 27b, 28a and 28b formed so as to be opposed to each other between the transverse beam deck portions 13b, 14b, 13c and 14c. It is rotatably supported through certain plain bearings 29 and 30.

  Further, as shown in FIG. 3, the driven side balancer shaft 10 has two cylindrical journal surfaces 10a and 10b formed on the front end side and the rear end side in the axial direction, respectively. The two journal surfaces 10a, 10b on the side are formed in two semicircular arc-shaped first and second portions respectively formed at positions facing the first to third transverse beam deck portions 13b-14d of the lower housing 13 and the upper housing 14, respectively. The bearing grooves 27b and 28b are rotatably supported through two plain bearings 29 and 30 which are bearings.

  Further, the driven-side balancer shaft 10 is integrally provided with two semi-circular first and second counterweights 31 and 32 in a longitudinally symmetrical position across the rear journal surface 9b. Both counterweights 31 and 32 have the same shape and the same weight.

  The driven gear 12 is fixed to the driven balancer shaft 10 by press fitting or the like, and as in the driving balancer shaft 9, as shown in FIG. 1A, in the groove formed in the lower housing 13, that is, facing the groove. The movement in the axial direction is restricted by being sandwiched between the thrust walls 13e and 13f.

  The rear end journal surface 10b provided between the first counterweight 31 and the second counterweight 32 is formed to have an outer diameter slightly larger than that of the front end side, and the first counterweight A part of the weight 31 side is notched, and the remaining surface 10e formed in the circumferential direction is formed smaller than the area of the journal surface 10a on the rear side of the notch 10d.

  That is, the front end side journal surface 10a is formed in an ordinary cylindrical shape, but the rear end side journal surface 10b is a circle on the first counterweight 31 side as shown in FIG. The notch 10d is formed in about 2/3 of the circumferential direction, and the remaining surface 10d remaining in the circumferential direction other than the notch 10d has a contact area with the sliding surface 30b of the rear end side plain bearing 30. The journal surface 10b remaining on the rear side is formed smaller than the contact area with the plain bearing 30.

  The reason is that, as in the case of the drive side, the second counterweight 32 is supported in a cantilevered state by one plain bearing 30 and the rear end side journal surface 10b. Although a large surface pressure acts on the rear end portion of the second counterweight 32 side, the surface pressure is smaller than that of the rear end portion because the front end portion on the first counterweight 31 side is supported in a dual-supported state. Because. Therefore, a notch portion 10d is formed on the front end side of the rear end side journal surface 10b where the surface pressure is reduced to reduce the contact area between the circumferential remaining surface 10e and the sliding surface 30b of the plain bearing 30. Is. Further, the journal surface 10b on the second counterweight 32 side of the rear end side journal surface 10b is formed in a cylindrical surface larger than the remaining surface 10e because the surface pressure increases.

  The first to fifth plain bearings 22 to 24, 29, and 30 on the driving side and the driven side are formed by dividing a metal flat plate into two halves in the vertical direction, and each of these halves is formed in each of the first bearing recesses. The grooves 19a to 21b and 27a to 28b are respectively fitted and fixed to form a cylindrical shape.

  Further, on the upper surface of the frame-shaped deck portion 13a and the cross beam deck portions 13b to 13d of each lower housing 13, a supply groove passage (not shown) for supplying lubricating oil to the plain bearings 22 to 24, 29, and 30 is provided. An annular ring that is continuously formed and communicates with the supply groove passage at a substantially central position in the width direction of each inner peripheral surface of each of the bearing concave grooves 19a to 21b, 27a, 27b, 28a, 28b. Oil grooves 33, 34, and 35 are respectively formed.

  The plain bearings 22 to 24, 29, and 30 are respectively provided with sliding surfaces 22b to 24b, which are inner peripheral surfaces, of lubricating oil supplied into the oil grooves 33 to 35 at a substantially central position in the width direction. Two communication holes that are not shown in the figure are formed so as to penetrate between 29b, 30b and each of the journal surfaces 9a-9c, 10a, 10b.

  The supply groove passage is configured with a lubricant oil supply passage together with the lower surfaces of the deck portions 14a to 14d in a state where the upper housing 14 is mounted and coupled to the lower housing 13, and is formed in the upstream end. Lubricating oil is supplied from the oil pump through the hole.

  The respective oil grooves 33 to 35 are formed in an annular shape between the respective bearing concave grooves 19a to 21b, 27a, 27b, 28a and 28b, and communicate with each other through the lubricating oil supply grooves.

  In addition, an oil discharge hole (not shown) for returning the oil stored in the housing 8 into the oil pan 5 is formed in the upper wall portion of the upper housing 14 on the drive side balancer shaft 9 side.

  Therefore, according to the balancer device 7, when the engine is started and the crankshaft 3 is rotationally driven, the drive-side balancer shaft 9 is twice the crankshaft 3 via the crank sprocket 6, the drive chain 18 and the balancer sprocket 17. Rotate at a speed of. As a result, the driven-side balancer shaft 10 rotates at the same speed in the opposite direction to the driving-side balancer shaft 9 via the meshing rotation transmission between the driving-side gear 11 and the driven-side gear 12.

  As a result, the counterweights 25, 26, 31, and 32 also rotate in opposite directions to cancel the left and right centrifugal forces of the balancer shafts 9 and 10 themselves.

  At this time, the housing 8 prevents the oil staying in the oil pan 5 from interfering with the balancer shafts 8 and 9, and receives the vibration generated when the balancer shafts 8 and 9 rotate. Transmit vibration to the engine.

  As described above, the counterweights 25, 26, 31, and 32 are rotated with the rotation of the balancer shafts 9 and 10 to transmit the excitation force to the internal combustion engine 1, thereby suppressing the secondary vibration.

  In the present embodiment, the notch portions 9d and 10d are formed at the front end portions on the first counterweights 25 and 31 side where the surface pressure of the rear end side journal surfaces 9b and 10b is small, respectively. 10b and the respective sliding surfaces 23b, 30b of the plain bearings 23, 30 on which they slide, the surface area 9b during rotation of the drive-side balancer shaft 9 and the driven-side balancer shaft 10 is reduced. , 23b, 10b, 30b, the sliding friction can be reduced.

  Therefore, the rotational load of the drive side balancer shaft 9 and the driven side balancer shaft 10 as a whole is reduced, and the drive load of the engine can be reduced. As a result, the fuel efficiency of the engine can be improved.

  Further, by forming the notches 9d and 10d in the journal surfaces 9b and 10b of the balancer shafts 9 and 10, the balancer shafts 9 and 10 can be reduced in weight, so that the friction between them can be further reduced, The effect of reducing the rattling noise between the driving gear 11 and the driven gear 12 and the striking sound in the thrust direction, that is, vibration and noise (sound vibration) can also be obtained.

[Second Embodiment]
FIG. 5 shows a second embodiment of the present invention, in which the second counterweight is eliminated and only one counterweight 25 is provided at the rear end of the drive side balancer shaft 9. The two journal surfaces 9a and 9b formed in the above are supported by two plain bearings 22 and 23 in a both-end supported state.

  The front journal surface 9a has a first notch 9f formed at the front end of the drive gear 11 side, while the rear journal surface 9b has a second notch 9g formed at the rear end. The remaining surfaces 9h and 9i of the first notch 9f and the second notch 9g remain in the circumferential direction by about 1/3.

  That is, in this structure, when the drive-side balancer shaft 9 rotates, the load due to the mass of the counterweight 25 is received at the front and rear portions of the journal surfaces 9a and 9b on the counterweight 25 side. As described in the lower side of FIG. 5, the surface pressure distribution on the sliding surfaces 22 b and 23 b of the bearings 22 and 23 is such that the rear portion of the counterweight 25 is on the front journal surface 9 a and the rear journal surface 9 b is The front part of the counterweight 25 is the highest, and it becomes smaller at the part on the opposite side in the axial direction.

  Therefore, in the present embodiment, the first journal surface 9a is formed with the first notch 9f at the front end portion on the drive side gear 11 side where the surface pressure is reduced, while the rear journal surface 9b has a surface pressure. A second cutout portion 9g is formed at the rear end portion where becomes smaller.

  The journal surfaces 10a and 10b of the follower-side balancer shaft 10 (not shown) have the same configuration as the drive-side journal surfaces 9a and 9b. The area is small. Other configurations are the same as those of the first embodiment.

Therefore, this embodiment also reduces the contact area with respect to the remaining surfaces 9h, 9i, 10h, 10i and the sliding surfaces 22b, 23b, 29b, 30b formed by the notches 9f, 9g, 10f, 10g. The same effect as the first embodiment can be obtained.
[Third Embodiment]
FIG. 6 shows the third embodiment. The basic configuration is the same as that of the first embodiment, except that the notch 9d formed in the rear journal surface 9b is further largely cut toward the rear side in the axial direction. The residual width 9e is reduced in the axial width of the residual surface 9a, and the axial oil groove 35 is greatly cut away not in the axial direction but in the rear side so that the axial width is reduced. The surface 9e is arranged so as to be biased toward the center in the axial direction.

  Further, although not shown in the drawing, the notch portion 10d of the rear journal surface 10 of the driven side balancer shaft 10 is also greatly cut out in the axial direction as in the driving side balancer shaft 9, and the remaining surface 10e is reduced in the axial direction. In addition, the axial position of the oil groove 35 is deviated rearward.

  Therefore, according to this embodiment, the contact surfaces of the remaining surfaces 9e and 10e and the sliding surfaces 23b and 30b of the plain bearings 23 and 30 are greatly cut out in the axial direction. Can be further reduced, and the overall surface pressure can be reduced.

Further, the lubricity of the sliding surface is ensured by biasing the formation positions of the oil grooves 35, 35 to the axial center positions of the journal surfaces 9b, 10b.
[Fourth Embodiment]
FIG. 7 shows a fourth embodiment, which also has a basic configuration similar to that of the third embodiment, except that the plain bearings 22, 23, 24, 29, and 30 used in the respective embodiments are different. The journal surfaces 9a to 9c, 10a, and 10b are abolished and directly supported by the inner peripheral surfaces of the bearing concave grooves 19a, b20a, b, 21a, b, 27a, b, 28a, and b. .

Therefore, according to this embodiment, the same operational effects as those of the second embodiment can be obtained, and the number of parts can be reduced and the manufacturing cost can be reduced by eliminating the plain bearings 22, 23, 24, 29, and 30. As a result, assembly costs can be reduced.
[Fifth Embodiment]
FIG. 8 shows a fifth embodiment, and the basic configuration is the same as that of the third embodiment, except that the plain bearings 22, 23, 24, 29, and 30 are used as bearings for the balancer shafts 9 and 10, respectively. All of them are needle bearings 40. Further, the oil grooves 34 and 35 for supplying lubricating oil are eliminated.

  Therefore, according to this embodiment, it is possible to obtain the lubricating oil supply including the oil grooves 34 and 35 by using the bearing as the needle bearing 40 as well as the same effects as the above-described embodiments. Since no means is required, there is no need to form an oil groove or the like, and the manufacturing operation is facilitated.

  In the balancer device of the present invention, the outer diameters and lengths of the balancer shafts 9 and 10 and the sizes of the counterweights 25, 26, 31, 32 and the like are variously changed according to the size and specifications of the displacement of the internal combustion engine. It can also be applied to things.

The technical ideas of the invention other than the claims ascertained from the embodiment will be described below.

[A] A balancer device for an internal combustion engine according to claim 2,
The balancer device for an internal combustion engine, wherein the bearing is a plain bearing.
[B] A balancer device for an internal combustion engine according to claim 2,
The balancer device for an internal combustion engine, wherein the bearing is formed integrally with the housing.
[Claim] A balancer device for an internal combustion engine according to claim 1,
The balancer device for an internal combustion engine, wherein the bearing is constituted by a needle bearing.

DESCRIPTION OF SYMBOLS 1 ... Internal combustion engine 7 ... Balancer apparatus 8 ... Housing 9 ... Drive side balancer shaft 9a-9c ... Journal surface 9d, 9f, 9g ... Notch part 9e, 9h, 9i ... Remaining surface 10 ... Driven side balancer shaft 10a 10b: Journal surface 11: Drive side gear 12: Driven side gear 13: Lower housing 19a, 20a, 21a ... Bearing groove on the lower housing side (bearing)
19b, 20b, 21b ... Bearing groove on the upper housing side (bearing)
22-24 ... Plain bearings (bearings) on the drive side balancer shaft side
22b to 24b ... sliding surfaces 25 and 26 ... drive side counterweights 27a and 28a ... bearing housing grooves 27b and 28b on the lower housing side bearing grooves 29 and 30 on the upper housing side ... driven side balancer Plain bearing on the shaft side (bearing)
29b, 30b ... Sliding surfaces 31, 32 ... Driven side counterweight 40 ... Needle bearing

Claims (4)

A housing attached to the internal combustion engine;
A pair of front and rear bearings provided inside the housing;
A balancer shaft disposed in the housing and rotatably supported by a pair of journal surfaces formed on an outer periphery sliding on bearing surfaces of the pair of bearings;
A first counterweight provided integrally with the balancer shaft and disposed between the pair of bearings;
A second counterweight provided integrally with the balancer shaft and supported in a cantilevered state by one of the pair of bearings;
With
Of the journal surfaces located between the first and second counterweights of the balancer shaft, the contact area with the bearing surface on the first counterweight side is defined as the bearing surface on the second counterweight side. A balancer device for an internal combustion engine characterized by being formed smaller than the contact area of the internal combustion engine.   The balancer device for an internal combustion engine according to claim 1, wherein a plurality of lubricating oil supply holes are provided in each of the bearings, and an inner opening end of the lubricating oil supply hole is formed so as to face the journal surface. A balancer device for an internal combustion engine. A housing attached to the internal combustion engine;
Two bearings provided in the housing,
A balancer shaft rotatably supported in the housing by bearing one journal surface and the other journal surface spaced apart in the axial direction of the outer periphery on the respective bearing surfaces of the two bearings;
A counterweight provided between the two journal surfaces of the balancer shaft;
With
The two journal surfaces each have a surface on the counterweight side and a surface on the side away from the counterweight, and a contact area between the surface on the side away from the counterweight and the bearing surfaces. A balancer device for an internal combustion engine , wherein the counterweight side surface is smaller than a contact area with each bearing surface . A balancer shaft having a counterweight and a plurality of journal surfaces provided on the same axis for canceling rotational vibration of the internal combustion engine;
It said plurality of journal surfaces of the balancer shaft, and a plurality of bearings for rotatably supported via respective bearing surfaces,
With
One journal surface that slides on the bearing surface of the one bearing of the balancer shaft has a smaller contact area on the side where the surface pressure applied to the bearing surface of the one bearing is lower than the side where the surface pressure is high. A balancer device for an internal combustion engine.

Images