JP2012202442A - Balancer device for internal combustion engine and bearing structure of metal shaft - Google Patents

Abstract

PROBLEM TO BE SOLVED: To lower viscous friction between sliding surfaces of sliding bearings and balancer shafts by making the balancer shafts diameters smaller while suppressing a separation phenomenon by increasing the hardness of the sliding surfaces of the sliding bearings.SOLUTION: A balancer device includes: a driving side balancer shaft 9 to which torque is transmitted from the crankshaft; a driven side balancer shaft 10 to which torque is transmitted from the driving side balancer shaft; a housing 8 which houses both the balancer shafts rotatably inside; and plane bearings 22-24, 29, 30 each provided between both the balancer shafts and bearing recessed grooves of the housing to bear both balancer shafts rotatably. The hardness of the journal surfaces 9a-9c, 10a, 10b of the balancer shafts are set to approximately 330 Hv, while the sliding surfaces 22b-24b, 29b, 30b of the plane bearings are formed of tungsten carbide (WWC) and set to the high hardness of approximately 1,350 HK.

Description

  The present invention relates to a balancer device for reducing secondary vibration of an internal combustion engine and a bearing structure for a metal shaft.

  As a conventional balancer device for an internal combustion engine, there is one described in Patent Document 1 below. Briefly described, a housing that is attached to the lower part of the crankcase of the engine and is accommodated in an oil pan, and is rotatably accommodated and supported in the housing via a slide bearing, and rotational force is transmitted from the crankshaft. A drive-side balancer shaft and a driven-side balancer shaft that is rotatably housed and supported by a sliding bearing and to which a rotational force is transmitted from the drive-side balancer shaft are 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. As a result, the secondary vibration of the engine is effectively suppressed by the rotation of each counterweight.

  The sliding bearing is formed of a soft material of 100 Hv or less with an aluminum alloy material applied to the sliding surface on which each balancer shaft slides, thereby absorbing (embedding) contamination such as metal powder inside. ).

JP 2008-14351 A

  However, in the balancer device, since a soft material is applied to the sliding surface of the sliding bearing, a large balancer shaft input (centrifugal force) acts on the sliding surface particularly at a high rotation speed. As a result, the friction between the balancer shaft and the journal surface increases, and the sliding surface peels off due to metal fatigue due to long-term sliding, which may cause seizure.

  The present invention increases the hardness of the sliding surface of the sliding bearing to increase the bearing strength and suppress the peeling phenomenon, while the hardness of the journal surface that slides on the sliding bearing is higher than the hardness of the sliding surface of the sliding bearing. Is set to be low, the area of the sliding surface of the sliding bearing that is elastically deformed is increased, and the load surface pressure applied to the sliding bearing during rotation of the balancer shaft is reduced, thereby reducing the shaft diameter of the balancer shaft. An object of the present invention is to provide a balancer device for an internal combustion engine.

In the first aspect of the present invention, the drive-side balancer shaft to which the rotational force is transmitted from the crankshaft, the driven-side balancer shaft to which the rotational force is transmitted from the drive-side balancer shaft, and both the balancer shafts. A housing rotatably accommodated therein, a slide bearing provided between the drive-side balancer shaft and the housing, and between the driven-side balancer shaft and the housing, and bearing both the balancer shafts rotatably. With
The sliding surface hardness of each of the sliding bearings is set higher than the hardness of the journal surface that slides on the sliding bearings of the two balancer shafts.

  According to the present invention, the peeling phenomenon can be suppressed by increasing the material strength of the slide bearing, and the elastic deformation area on the slide bearing sliding surface of the balancer shaft is increased, so that the slide bearing is rotated when the balancer shaft is rotated. As a result, the shaft diameter of the balancer shaft can be reduced.

BRIEF DESCRIPTION OF THE DRAWINGS The plain bearing provided to embodiment of the balancer apparatus which concerns on this invention is shown, A is a perspective view which shows the one part, B is the principal part enlarged view seen from the arrow direction of A. It is a disassembled perspective view of the balancer apparatus in this embodiment. It is a top view which shows the balancer apparatus which removed the upper housing in this embodiment. It is the figure which looked at the balancer apparatus which removed the lower housing from the bottom face side. It is the sectional view on the AA line of FIG. 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 characteristic view which shows the relationship between the moment of inertia of the rotating shaft center of a balancer shaft in this embodiment, and sensory evaluation.

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 with reference to the drawings.
[First Embodiment]
As shown in FIG. 6, 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 portion 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 part of the cylinder block 2 by bearing bolts (not shown), and is large on a shaft 3a that is integrally provided on the front end side. A 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. 2 to 5, the balancer device 7 includes a housing 8 fixed to the lower surface of the oil pan 5, and is rotatably supported inside the housing 8, and is arranged in parallel in the longitudinal direction of the engine. The drive-side balancer shaft 9 and the driven-side balancer shaft 10 and the helical-type drive-side gear 11 and the driven-side gear, which are provided on substantially the center side of each of the balancer shafts 9 and 10 and in which the tooth portions mesh with each other. And a 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. 2 to 5, the drive-side balancer shaft 9 is fixed to the front end portion of the tip shaft 9 c by a fixing bolt 16 in which a balancer sprocket 17 is screwed from the axial direction, and the balancer sprocket 17. And the rotational force from the crankshaft 3 is transmitted via the drive chain 18 wound between the crank sprocket 6 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. 3 to 5, the drive-side balancer shaft 9 is formed with 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 semicircular arc-shaped first to third bearings in which the journal surfaces 9a to 9c 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. The grooves 19a, 19b, 20a, 20b, 21a, 21b are rotatably supported via plain bearings 22, 23, 24 which are sliding bearings.

  Two semicircular first and second balance weights 25 and 26 are integrally provided at the symmetrical positions before and after the rear journal 9b of the drive side balancer shaft 9 is sandwiched. Both balance weights 25 and 26 are formed in the same shape and the same weight.

  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.

  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. Slide bearings are provided in the two semicircular arc-shaped fourth and fifth bearing grooves 27a, 27b, 28a, and 28b formed with the surfaces 10a and 10b facing each other between the cross beam deck portions 13b, 14b, 13c, and 14c. These are supported rotatably via plain bearings 29 and 30.

  Each journal surface 9a-9c, 10a, 10b is a relatively soft metal material without quenching.

  Further, the driven-side balancer shaft 10 is integrally provided with two semicircular arc-shaped first and second balance weights 31 and 32 at a longitudinally symmetrical position across the journal surface 9b on the rear side. Both balance weights 31 and 32 are set to 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 shown in FIG. 5, by a thrust wall 13e, 13f opposed to the groove in the groove formed in the lower housing 13, as shown in FIG. The movement in the axial direction is regulated by being sandwiched.

  The journal surfaces 9a to 9c, 10a, and 10b of the drive-side and driven-side balancer shafts 9 and 10 are set to have a hardness of about 330 Hv.

  The first to fifth plain bearings 22 to 24, 29, and 30 on the driving side and the driven side are formed by dividing the metal flat plate into two halves vertically as shown in FIGS. The half portion is formed in a cylindrical shape by being fitted and fixed in the first bearing grooves 19a to 21b and 27a to 28b. The plain bearings 22 to 24, 29, and 30 are set to have substantially the same axial width.

  Each of the plain bearings 22 to 24, 29, and 30 has a tungsten carbide carbon (WCC) which is formed of a rolled steel plate on the outer peripheral side and is a hard alloy layer on the sliding surface on the inner peripheral side. ) Is coated.

  Hereinafter, as shown in FIGS. 1A and 1B, a plain bearing 22 provided on the lower housing 13 side on the drive side balancer shaft 9 side described as a representative example will be specifically described.

  That is, the plain bearing 22 is formed by bending the outer peripheral base material 22a into a semicircular arc shape with a rolled steel plate having high hardness, while the inner peripheral sliding surface 22b is coated with the WCC. An alloy layer is formed. The hardness of the sliding surface 22b is set to about 1350HK which is considerably higher than the hardness (about 330HB) of the journal surface 9a of the drive side balancer shaft 9. While the plain bearings 22-24, 29, 30 are set to high hardness, the journal surfaces 9a-9c, 10a, 10b of the balancer shafts 9, 10 are compared with the plain bearings 22-24, 29, 30. And low hardness (low Young's modulus). Therefore, by increasing the area of the bearing contact surface of the balancer shaft 9 that is elastically deformed, the load surface pressure applied to the plain bearings 22 to 24, 29, and 30 when the balancer shaft 9 rotates can be reduced.

  Note that the coating thickness of the sliding surface 22b is set to be thinner than that of a conventional soft material.

  Further, as shown in FIG. 3, lubrication for supplying lubricating oil to the plain bearings 22 to 24, 29, and 30 is performed on the upper surfaces of the frame-shaped deck portions 13a and the cross beam deck portions 13b to 13d of the lower housings 13, respectively. An oil supply groove 33 is formed continuously, and an oil groove 34 communicating with the lubricating oil supply groove 33 is formed on each inner peripheral surface of each of the bearing concave grooves 19a to 21b, 27a, 27b, 28a, 28b. Is formed.

  In addition, the lubricating oil supplied into the oil grooves 34, 34a is placed at the substantially central positions in the width direction of the plain bearings 22-24, 29, 30 and the sliding surfaces 22b-24b, 29b, 30b. Two communication holes 35 to be introduced between the journal surfaces 9a to 9c, 10a, and 10b are formed in a penetrating manner.

  The lubricating oil supply groove 33 forms a lubricating 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 an oil hole 33a formed at the upstream end. Lubricating oil is supplied from an oil pump (not shown). The lubricating oil supply groove 33 is formed in a circular shape so as to surround each bolt insertion hole 13h.

  The oil grooves 34 are formed in an annular shape between the bearing concave grooves 19 a to 21 b, 27 a, 27 b, 28 a, 28 b, and communicate with each other via the lubricating oil supply groove 33. Further, the formation positions of the second bearing groove 20a, 20b and the oil groove 34a on the fifth bearing groove 28a, 28b side coincide with the formation positions of the communication holes 35 of the second and fifth plain bearings 23, 30. It is supposed to be.

  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 balance weights 25, 26, 31, 32 also rotate in opposite directions to cancel the left and right centrifugal forces of the balancer shafts 9, 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 balance weights 25, 26, 29, and 30 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 secondary vibration.

  In the present embodiment, the entire sliding surfaces 22b to 24b, 29b, and 30b of the plain bearings 22 to 24, 29, and 30 are made of tungsten carbide carbon (WCC) having high hardness. Deformation of the sliding surfaces 22b-24b, 29b, 30b of the plain bearings 22-24, 29, 30 can be suppressed.

  That is, the balancer device is provided with balance weights 25, 26, 29, and 30 having large masses on the balancer shafts 9 and 10, so that each plane from the journal surfaces 9a to 9c, 10a, and 10b during the rotation is provided. This causes a technical problem peculiar to the balancer device such that the contact load of the bearings 22 to 24, 29, and 30 on the sliding surfaces 22b to 24b, 29b, and 30b becomes extremely large.

  Further, when the rotation transmission means from the crankshaft 3 to the drive side balancer shaft 9 is the drive chain 18 as in this embodiment, the journal surface 9c and the plain bearing 24 closest to the mounting portion of the balancer sprocket 17 are used. Because of high tension acting on the bearing, excessive friction is generated. Therefore, when the sliding surface of the plain bearing 24 is made of a soft metal material as in the prior art, the sliding surfaces 22b to 24b of the plain bearings 22 to 24, 29 and 30 are caused by the same technical problem as described above. The phenomenon that 29b and 30b deform | transform and peel will generate | occur | produce.

  Therefore, in the present embodiment, unlike the conventional technique, the sliding surfaces 22b to 24b, 29b, and 30b are formed of WCC having high hardness, so that the sliding of the plain bearings 22 to 24, 29, and 30 is performed. The deformation of the surfaces 22b to 24b, 29b, and 30b can be suppressed.

  As a result, the peeling phenomenon of the sliding surfaces 22b to 24b, 29b, 30b is sufficiently suppressed, and durability can be improved.

  In addition, the outer diameters of the drive-side balancer shaft 9 and the driven-side balancer shaft 10 are compared with the conventional ones by increasing the hardness of the sliding surfaces 22b-24b, 29b, 30b of the plain bearings 22-24, 29, 30. Can be made thin. Thereby, the viscous friction (surface pressure (allowable surface pressure)) between each said journal surface 9a-9c, 10a, 10b and each sliding surface 22b-24b, 29b, 30b can be reduced. As a result, it is possible to further reduce the friction and improve the fuel consumption of the internal combustion engine.

  Further, when contaminants such as metal powder enter between the journal surfaces 9a to 9c, 10a and 10b and the sliding surfaces 22b to 24b, 29b and 30b, the contaminants are slid as in the conventional case. Instead of being buried in the moving part, the journal surfaces 9a to 9c, 10a and 10b having high hardness and the sliding surfaces 22b to 24b, 29b and 30b are crushed and discharged to the outside as they are. For this reason, it is possible to urgently avoid the influence of contamination.

  In addition, it is possible to cope with the high surface pressure between the journal surfaces 9a to 9c, 10a, and 10b and the sliding surfaces 22b to 24b, 29b, and 30b as described above. The outer diameters of the balancer shafts 9 and 10 can be reduced, and the axial width between the journal surface and the sliding surface can be reduced.

  Thus, since the balancer shafts 9 and 10 can be reduced in weight by reducing the diameters of the balancer shafts 9 and 10 and narrowing the journal surface, the friction between them can be further reduced, and the drive side gear can be reduced. Further, it is possible to obtain the effect of reducing the rattling noise between the gear 11 and the driven gear 12 and the striking sound in the thrust direction, that is, vibration and noise (sound vibration).

  That is, as shown in the graph of FIG. 7, the inertial moment about the rotating shafts of the balancer shafts 9 and 10 is reduced by the weight reduction (decrease in the inertial mass), so the sensory rating of the sound vibration is also good. become.

[Other Embodiments]
In the said embodiment, although the said sliding surfaces 22b-24b, 29b, 30b were comprised by WWC, as another alloy layer, for example, diamond-like carbon (DLC), chrome nitride (CrN), titanium nitride (TiN) ), Aluminum titanium nitride (TiAIN), titanium carbon (TiC), aluminum chrome titanium nitride (AICrN), or the like.

  Further, the hardness of each of the journal surfaces 9a to 9c, 10a and 10b can be set to 170 to 241HB of 330HB or less, and by using such a low hardness, the material cost can be reduced. In addition, the contamination can be temporarily accommodated in the wear groove on the sliding surface of the balancer shaft formed by the contamination.

  The balancer device of the present invention can be applied to various balancer shafts 9 and 10 having different outer diameters and lengths and balance weights depending on the size and specifications of the internal combustion engine. It is.

  The bearing structure of the present invention can also be applied to a shaft bearing structure having an unbalanced portion such as a crankshaft of an internal combustion engine.

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 1 or 2,
A balancer device for an internal combustion engine, wherein an alloy layer is formed on a sliding surface of the sliding bearing by coating.
[B] A balancer device for an internal combustion engine according to claim a,
A balancer device for an internal combustion engine, wherein the sliding bearing alloy layer is formed of tungsten carbide.
[Claim c] A balancer device for an internal combustion engine according to claim a,
A balancer device for an internal combustion engine, wherein the alloy layer of the sliding bearing is formed of diamond-like carbon.
[Claim d] A balancer device for an internal combustion engine according to claim a,
A balancer device for an internal combustion engine, wherein the alloy layer of the slide bearing is formed of chromium nitride.
[Claim e] A balancer device for an internal combustion engine according to claim 1 or 2,
A balancer device for an internal combustion engine, wherein the slide bearing is formed by two half-arc-shaped divided pieces.
[Claim f] The balancer device for an internal combustion engine according to claim 1 or 2,
A balancer device for an internal combustion engine, wherein the hardness of the journal surface of the both balancer shafts with the sliding bearing is set to about 330 Hv, and the hardness of the sliding surface of the sliding bearing is set to 1350 HK or higher.

DESCRIPTION OF SYMBOLS 1 ... Internal combustion engine 7 ... Balancer apparatus 8 ... Housing 9 ... Drive side balancer shaft 9a-9c ... Journal 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 concave grooves 19b, 20b, 21b on the lower housing side Bearing concave grooves 25, 26 on the upper housing side ... Balance weights 22-24 of the drive side balancer shaft .. plain bearings 22b to 24b on the drive side balancer shaft ... sliding surfaces 21a and 21b ... balance weights 24a and 24b on the drive side balance weights 27a and 28a on the driven side ..Bearing grooves 29, 30 on the upper housing side ... Driver side balancer Yafuto side of the plane bearing 29b, 30b ... sliding surfaces 31, 32 ... balance weight of the driven balancer shaft

Claims (3)

A drive-side balancer shaft to which rotational force is transmitted from the crankshaft;
A driven side balancer shaft to which rotational force is transmitted from the drive side balancer shaft;
A housing which accommodates both the balancer shafts rotatably inside;
A sliding bearing provided between the drive-side balancer shaft and the housing, and between the driven-side balancer shaft and the housing, and rotatably bearing both the balancer shafts;
With
A balancer device for an internal combustion engine, characterized in that the hardness of the sliding surface of each sliding bearing is set higher than the hardness of the journal surface that slides on the sliding bearing of both balancer shafts. A driving-side balancer shaft to which rotational force is transmitted from the crankshaft and having at least one balancer weight on the outer periphery;
A driven side balancer shaft to which rotational force is transmitted from the drive side balancer shaft and having at least one balance weight on the outer periphery;
A housing which accommodates both the balancer shafts rotatably inside;
A sliding bearing provided in the housing and rotatably bearing both shafts;
With
A balancer device for an internal combustion engine, characterized in that an allowable surface pressure of a sliding surface of the sliding bearing is set to be higher than an allowable surface pressure of a journal surface sliding on the sliding bearing of both balancer shafts. A shaft provided with an unbalanced portion on the outer peripheral surface, a support member that supports the shaft, a slide bearing that is provided between the shaft and the support member and rotatably supports the shaft;
With
A shaft bearing structure characterized in that the hardness of the sliding bearing is set higher than the hardness of a journal surface on which the sliding bearing of the shaft slides.

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