JP2008169906A - Balancer device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a balancer device wherein at the time of rotation of a balancer shaft, the resistance of oil to a balancer weight is reduced. <P>SOLUTION: The balancer device 1 is provided with a drive shaft 8, which is freely rotatably supported in a lower housing 7. In the drive shaft 8, a first balancer weight 18 is integrally provided at an axially specified position, and with the rotation, the balancer weight 18 is brought into contact with the oil stored in the lower housing. The first balancer weight is nearly semicircularly formed in its cross section with the axial center C of a shaft body 8d of the drive shaft as its center. The balancer weight has a large planar part 21a in continuation with the shaft body, and a large diameter circular-arc part 21b formed on the symmetrical side with respect to the shaft body from the large planar part. A tapered face 21c in a chamfered shape is axially formed between the large planar part and the large diameter circular-arc part. Thus, at the time of rotation, the resistance of the oil to the tapered face is reduced. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a balancer device that is provided, for example, in an internal combustion engine of a vehicle and suppresses secondary vibration of a crankshaft, and more particularly to an improvement of a balancer shaft that is rotatably provided in the balancer device.

  As a conventional balancer device provided in an internal combustion engine of a vehicle, for example, the one described in Patent Document 1 below is known.

  The balancer device is disposed below the cylinder block of the engine, and is provided with a balancer housing composed of an upper housing and a lower housing which are divided into upper and lower portions, and each balancer device is rotatably provided in the balancer housing. And two balancer shafts having a balancer weight having a substantially semicircular cross section in the position.

  Each of the balancer shafts has helical gears that mesh with each other, and is arranged parallel to the crankshaft supported on the lower portion of the cylinder block along the axial direction. One balancer shaft is linked to the crankshaft via a chain and is rotated by the rotational force of the crankshaft, and the other balancer shaft is rotated in the circumferential direction opposite to the balancer shaft along with the rotation. It is supposed to be.

Each of the balancer shafts is set to rotate at a speed twice that of the crankshaft, and by rotating each of the balancer shafts, a centrifugal force is generated by each balancer weight. The secondary vibration of the crankshaft applied from the piston or connecting rod is canceled.
JP-A-6-33989

  By the way, a part of the oil circulating in the engine is stored in the balancer housing, and when the oil surface (oil level) is in the vicinity of the height position of the balancer shaft, the balancer shaft When the is rotating, the balancer weight collides with the oil surface.

  At this time, in the conventional balancer device, the outer shape of the balancer weight is formed in a substantially semicircular shape in cross section, and a flat portion formed on the shaft body side of the balancer shaft and a substantially semicircular arc portion. Therefore, the angle formed by the edge of the flat portion and the oil surface when the balancer weight enters the oil surface is large, which increases the resistance of the balancer weight to the oil surface. Yes.

  This large resistance causes a large energy loss when the balancer shaft rotates, thereby increasing the driving resistance of the balancer device. As a result, the load of the engine driving the balancer device is increased. It has been done.

  The present invention has been devised by paying attention to such a technical problem, and provides a balancer device that can reduce resistance caused by oil received by a balancer weight when a balancer shaft rotates.

  The invention according to claim 1 includes a balancer housing in which oil is stored, and a balancer shaft that is rotatably disposed in the balancer housing and integrally has a balancer weight at a predetermined position in the axial direction. A balancer device in which at least a part of the balancer weight comes into contact with the oil surface of the oil in accordance with the rotation of the balancer shaft, and a chamfered notch is formed along the axial direction at the edge of the balancer weight in the rotation direction. A balancer device characterized by being provided.

  According to the present invention, when the end edge of the balancer weight in the rotation direction comes into contact with the oil surface, the notch can smoothly guide and escape the oil to the rear side in the rotation direction of the balancer weight. Become. Therefore, resistance due to oil received when the balancer weight rotates can be reduced, and the drive efficiency of the apparatus can be improved.

  The invention according to claim 2 is characterized in that the notch portion is formed by a tapered surface having an angle that opens from an end surface in the rotation direction of the balancer weight toward an end surface on the rear side in the rotation direction.

  According to the present invention, a part of the resistance force of the oil acting on the opposite side of the balancer weight in the rotation direction is reduced by the tapered surface that opens from the end surface in the rotation direction of the balancer weight toward the end surface on the rear side in the rotation direction. Since it can be swept away, it is possible to reduce the resistance caused by the oil received when the balancer weight rotates.

  The invention according to claim 3 is characterized in that the notch is formed in a substantially arc shape in cross section.

  According to this invention, when the balancer weight is rotated, the oil can be more smoothly guided to the opposite side in the rotation direction along the outer peripheral surface of the notch formed in a substantially arc shape. The resistance due to the oil received by the balancer weight during contact with the oil surface and movement within the oil is more effectively reduced.

  Embodiments of a balancer device according to the present invention will be described below in detail with reference to the drawings. In each embodiment, the balancer device is applied to a vehicle engine as in the prior art.

  1 to 5 show a first embodiment of a balancer device according to the present invention. As shown in FIG. 3, the balancer device 1 supports a crankshaft 3 below a cylinder block 2 of an engine. It is attached and fixed via a ladder frame 4 having bearings. An oil pan 5 is fixed to the lower portion of the ladder frame 4 so as to cover the balancer mechanism 1 from below and in which lubricating oil is stored.

  The balancer mechanism 1 is supported between the upper housing 6 and the lower housing 7, which are balancer housings fixed together by a plurality of bolts 10 on the lower surface of the ladder frame 4, and the housings 6 and 7, and A drive shaft 8 and a driven shaft 9 which are balancer shafts arranged in parallel to the shaft 3; helical gears 11 and 12 which are fixed to one end side in the axial direction of the shafts 8 and 9 and meshed with each other; It has.

  Since the drive shaft 8 and the driven shaft 9 have substantially the same configuration, only the drive shaft 8 will be described below for convenience.

  The drive shaft 8 receives a rotational driving force from the crankshaft 3 via a drive chain 14 wound around a balancer sprocket 13 fixed at one end in the axial direction, and the helical gears 11 as shown in FIG. , 12 to rotate the driven shaft 9. Both shafts 8 and 9 are set to rotate twice per one rotation of the crankshaft 3.

  Further, as shown in FIGS. 1 and 4, the drive shaft 8 includes first, second, and third journal portions 8a to 8c formed at predetermined intervals in three axial directions. It is rotatably supported by three bearing portions 15a to 15c formed between the upper housing 6 and the lower housing 7 through substantially cylindrical plain bearings 14a to 14c fitted to the journal portions 8a to 8c, respectively. Has been.

  Each of the bearing portions 15a to 15c has a substantially annular groove groove 16a to 16c formed in the inner peripheral surface thereof, and the bearings 14a to 14c are formed in the housings 6 and 7, respectively. It is lubricated by the oil introduced through the oil passage formed outside the figure.

  Further, the drive shaft 8 is restricted from moving in the axial direction via the helical gear 11 by thrust receiving portions 17 a and 17 b formed at one end of the lower housing 7.

  Further, first and second balancer weights 18 and 19 are integrally provided on the other axial end of the drive shaft 8 so as to sandwich the third journal portion 8c. Since the balancer weights 18 and 19 have substantially the same structure although slightly different in size, only the first balancer weight 18 will be described below for convenience.

  As shown in FIGS. 1 and 2, the first balancer weight 18 is integrally formed with the drive shaft 8 by forging, and the semicircular side of the shaft main body 8d of the drive shaft 8 is increased in diameter. It has been done.

  That is, the first balancer weight 18 is formed in a substantially half-moon-shaped cross section centered on the axis C of the shaft body 8d, and has a small diameter portion 20 provided on the other axial end side, and the small diameter portion. And a large-diameter portion 21 provided in a step-diameter enlarged shape from 20 to one end side in the axial direction.

  The small-diameter portion 20 and the large-diameter portion 21 are formed continuously with the shaft portion main body 8d, and are formed on the same plane that passes through the axis C of the shaft portion main body 8d. A portion 21a, and a small-diameter arc portion 20b and a large-diameter arc portion 21b respectively formed on the sides symmetrical to the shaft body 8d from the flat portions 20a and 21a.

  Further, taper surfaces 20c and 21c, which are chamfered cutout portions, extend along the axial direction between the flat surface portions 20a and 21a of the small diameter portion 20 and the large diameter portion 21 and the circular arc portions 20b and 21b. Is formed.

  The tapered surfaces 20c and 21c have substantially the same size, and are notched so as to have an opening angle from a predetermined position in the radial direction of the flat portions 20a and 21a toward the arc portions 20b and 21b. As shown in FIG. 2, the opening angle θ is formed and is set to about 55 ° with respect to the plane portions 20 a and 21 a.

  Hereinafter, the operation of the balancer device 1 according to the present invention will be described. Since the basic operation of the device is well known, the description thereof will be omitted, and only the characteristic operation will be described with reference to FIG.

  In the balancer device 1, a driving force is applied to the crankshaft 3 by reciprocating movement of the piston simultaneously with the start of the engine. The driving shaft 8 rotates as described above and the helical gears 11 and 12 are driven by the driving force of the crankshaft 3. The driven shaft 9 is driven to rotate through the.

  At this time, when the level of the oil stored in the oil pan 5, that is, the height L of the oil surface 22 is at least in a position in contact with the first balancer weight 18 of the drive shaft 8, the drive shaft 8. When the first balancer weight 18 rotates with the rotation, the balancer weight 18 receives a reaction force (resistance) due to oil in a direction opposite to the rotation direction.

  Therefore, in the present embodiment, for ease of explanation, as shown in FIG. 2, the height L of the oil surface 22 is at a position where only the large diameter portion 21 of the first balancer weight 18 contacts the oil. Explaining the case, when the first balancer weight 18 enters the oil, first, the tapered surface 21c formed on the edge side in the rotation direction of the large diameter portion 21 collides with the oil surface 22. Due to this collision, a reaction force F due to oil acts on the tapered surface 21c in the direction of the thick arrow in the figure.

  The reaction force F acts in parallel with the opposite side of the rotation direction of the first balancer weight 18, that is, along the oil surface 22, so that the force received by the tapered surface 21c is indicated by a thin arrow in FIG. As shown, it can be broken down into a component force f1 acting in a direction perpendicular to the tapered surface 21c and a component force f2 acting in a horizontal direction against the taper surface 21c.

  The vertical component force f1 directly acts as a force that prevents the rotation so as to push back the large-diameter portion 21, while the horizontal component force f2 extends along the tapered surface 21c. The oil acts to flow outwardly in the radial direction of the large diameter portion 21.

  That is, the horizontal component force f2 acts so as to guide and release oil along the outer surfaces of the tapered surface 21c and the arc portion 21b along with the rotation of the first balancer weight 18. As a result, when the first balancer weight 18 is rotated, the oil can be smoothly pushed out to the opposite side of the rotation direction of the large diameter portion 21 as shown by a two-dot chain line in FIG.

  Thus, the horizontal component force f2 acts as a force for sending oil to the opposite side of the rotation direction of the large-diameter portion 21, and only the other vertical component force f1 is the large-diameter portion 21. It acts as a substantial resistance force against the rotation of. In other words, the resistance caused by the oil based on the reaction force F is converted into the vertical component force f1 by the tapered surface 21c, and is reduced by the horizontal component force f2.

  Such an effect can be obtained not only when the large-diameter portion 21 contacts the oil surface 22 but also when the large-diameter portion 21 rotates in the oil, and the small-diameter portion 20 can be obtained similarly.

  Therefore, according to this embodiment, since the tapered surface 21c is formed at the edge of the large diameter portion 21 in the rotation direction, as described above, the resistance due to the oil that the large diameter portion 21 receives during rotation is reduced. Can be reduced. As a result, the driving efficiency of the balancer device 1 can be improved, and the load on the engine can be reduced accordingly.

  Further, since each of the tapered surfaces 20c and 21c is formed on the first balancer weight 18, sharp portions in the outer shape of the first balancer weight 18 are eliminated, so that when the drive shaft 8 is forged. Generation of burrs can be suppressed. As a result, it is not necessary to perform deburring separately after the drive shaft 8 is molded, and the workability can be improved.

  Further, by forming the tapered surfaces 20c and 21c, it is possible to improve the releasability when the drive shaft 8 is forged and to suppress die seizure. Therefore, the workability can be improved also in this respect.

  FIG. 6 shows a second embodiment according to the present invention. The basic configuration is the same as that of the first embodiment, and the tapered surfaces 20c and 21c are formed in a substantially arc shape. is there.

  According to this embodiment, when the first balancer weight 18 comes into contact with the oil surface 22 and rotates in the oil, it is formed in a substantially arc shape as shown by a two-dot chain line in the figure. Further, the oil can be guided more smoothly to the opposite side of the rotation direction of the first balancer weight 18 along the smooth outer shape of each tapered surface 20c, 21c, so that the resistance that the first balancer weight 18 receives from the oil Can be more effectively reduced, and the drive efficiency of the balancer device 1 can be further improved.

  Further, since each of the tapered surfaces 20c, 21c is formed in a substantially arc shape, the outer shape of the first balancer weight 18 is formed in a smoother shape having no corners, so that the drive shaft 8 is forged. The generation of burrs during the process is more effectively suppressed.

  The technical ideas other than the invention described in each of the claims ascertained from the respective embodiments will be described below.

(1) The balancer weight is formed in a semicircular cross-section on the semicircular side of the shaft body of the balancer shaft with the shaft center of the balancer shaft as a center, and a flat portion formed on the shaft body side A circular arc portion protruding radially outward from the plane portion,
The balancer device according to any one of claims 1 to 3, wherein the notch is formed between the flat portion and the arc portion.

  According to this invention, since the effect similar to each invention of the said Claims 1-3 is obtained, since the sharp part comprised from the said plane part and the said circular arc part is excised, In particular, the generation of burrs when performing forging can be suppressed.

  (2) The balancer device according to claim 1, wherein the balancer shaft is formed by forging.

  According to this invention, by providing the notch, it is possible to give the notch a gradient, so that forging formability is improved in terms of die seizure and releasability. Processing workability is improved.

  (3) The balancer apparatus according to claim 1, wherein the balancer shaft has a plurality of balancer weights formed in different sizes.

  As described above, the present invention is not limited to the configuration of each of the above-described embodiments. For example, the shapes and sizes of the upper housing 6 and the lower housing 7, for example, the shapes and sizes of the drive shaft 8 and the driven shaft 9, In particular, the shape and size of the balancer weight provided on each of the shafts 8 and 9 can be freely changed according to the specifications and size of the engine.

  In the above-described embodiments, only the drive shaft 8 has been described with respect to the operational effects of the present invention. However, even with the driven shaft 9, the same operational effects as the operational effects of the drive shaft 8 can be obtained.

BRIEF DESCRIPTION OF THE DRAWINGS It is a perspective view of the drive shaft and driven shaft which show 1st Embodiment of the balancer apparatus which concerns on this invention, and demonstrates the principal part of this invention. It is the sectional view on the AA line of FIG. It is the schematic which shows the arrangement | positioning relationship of the balancer apparatus which concerns on this invention. FIG. 4 is a sectional view taken along line BB in FIG. 3. It is CC sectional view taken on the line of FIG. It is sectional drawing of the balancer weight which shows 2nd Embodiment of the balancer apparatus which concerns on this invention, and demonstrates the principal part of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Balancer apparatus 6 ... Upper housing (balancer housing)
7 ... Lower housing (balancer housing)
8 ... Drive shaft (balancer shaft)
9 ... Driven shaft (balancer shaft)
18 ... 1st balancer weight (balancer weight)
19 ... Second balancer weight (balancer weight)
20c: Tapered surface (notch)
21c ... Tapered surface (notch)

Claims (3)

A balancer housing in which oil is stored,
A balancer shaft that is rotatably disposed in the balancer housing and integrally has a balancer weight at a predetermined axial position;
With the rotation of the balancer shaft, at least a part of the balancer weight is in contact with the oil surface of the oil,
A balancer device, wherein a chamfered cutout portion is provided along an axial direction at an end edge of the balancer weight in the rotation direction. 2. The balancer device according to claim 1, wherein the cutout portion is formed by a tapered surface having an angle that opens from an end surface of the balancer weight in a rotation direction toward an end surface on the rear side in the rotation direction. The balancer device according to claim 1, wherein the notch is formed in a substantially arc shape in cross section.

Images