JP3730557B2 - Balancer shaft for engine balancing device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a balancer shaft of an engine balancing device having an eccentric weight portion.
[0002]
[Prior art]
Japanese Utility Model Publication No. 3-18761 discloses a balancing device in which a balancer shaft having an eccentric weight portion is disposed below a crankshaft.
[0003]
In the above-mentioned publication, in order to define the axial position of the balancer shaft, a thrust receiving surface provided in the journal portion of the balancer shaft is in sliding contact with the opening end surface of the bearing hole. It is also known to integrally form a thrust receiving surface on the balancer shaft in order to reduce the number of parts.
[0004]
[Problems to be solved by the invention]
By the way, the thrust receiving surface formed integrally with the journal portion must naturally be larger than the diameter of the journal portion. Therefore, according to the above-described conventional structure, the portion on the non-weight side has a flange shape regardless of the position of the weight. Therefore, since the outer peripheral side has a cantilever structure, the rigidity tends to be insufficient.
[0005]
The present invention has been devised to solve such problems of the prior art, and its main object is to improve the rigidity of the flange-shaped thrust receiving surface. It is to provide a balancer shaft of a balancing device.
[0006]
A second object of the present invention is to provide a balancer shaft of an engine balancing device which is improved so that an increase in weight due to reinforcement can be minimized.
[0007]
[Means for Solving the Problems]
In order to achieve such an object, the invention of claim 1 of the present application is directed to a thrust receiving surface (19) having a diameter larger than that of the journal portion (16c) so as to restrict the axial movement of the eccentric weight portion (17). In the balancer shaft (13L / 13R) of the balance device (4) for an engine having a journal portion integrally formed with a flange portion (18) having two of the journal portions, two journal portions are provided at both axial ends of the eccentric weight portion. The flange portion is provided in one of the two journal portions (16c), and the eccentric weight portion includes a shaft portion (20) having a diameter smaller than the diameter of the journal portion, thereby the mutually facing end surfaces for axially between the flange portion and the other of the journal portion and (16d) are formed, prior to said flange portion and the other journal portion (16d) A rib (21) which is connected between the end faces in the axial direction and whose height is gradually reduced so that the intermediate portion in the axial direction becomes a trough is extended to the anti-weight side of the eccentric weight portion. It was supposed to be.
[0008]
In this way, the rigidity of the flange portion provided with the thrust receiving surface can be increased by connecting the rib, so that highly accurate thrust regulation can be performed. Also, since the ribs are extended in the axial direction and the middle part in the axial direction is a valley, the stress distribution is optimized to suppress the weight increase on the anti-weight side, and the journal parts of the eccentric weight part are The rigidity between them can be further increased.
[0009]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.
[0010]
1 and 2 show a mounting portion of a balance device in a reciprocating piston engine to which the present invention is applied. The engine E is an in-line four-cylinder engine in which the crankshaft 1 extends in the horizontal direction, and includes a cylinder block 2, a lower block 3, a balancing device 4, and an oil pan 5. The cylinder axis is inclined with respect to the orthogonal direction and mounted on the vehicle body.
[0011]
The balancing device 4 is for reducing the secondary vibration of the engine E caused by the reciprocating motion of the piston. The balancing device 4 is attached to the oil pan 5 by through bolts B1 inserted into the left and right side ends from below. The inner block is fastened to the lower surface of the lower block 3 (below the crankshaft 1). The balancing device 4 includes a large sprocket 7 fixed to the back side of the crank pulley 6 at the front end of the crankshaft 1 (hereinafter referred to as the crank pulley side), and the left side (hereinafter, the left and right direction toward the crank pulley). And a small sprocket 8 fixed to the front end of a balancer shaft (to be described in detail later) and a link chain 9 spanned between the large and small sprockets 6 and 7. The crankshaft 1 is driven to rotate by the rotational force of the crankshaft 1.
[0012]
The balancing device 4 includes a pair of left and right balancer shafts 13L and 13R having substantially the same shape, and the center of both balancer shafts 13L and 13R so as to support and accommodate these two balancer shafts 13L and 13R in parallel with each other. 14U, and an upper housing 14U and a lower housing 14L which are divided into two vertically along a plane passing therethrough.
[0013]
Both the balancer shafts 13L and 13R are linked to each other by a helical gear 15 (only one of which is shown) integrally coupled to the balancer shafts 13L and 13R. Here, as described above, the driving force of the crankshaft 1 is transmitted to the left balancer shaft 13L via the large sprocket 7, the small sprocket 8, and the link chain 9, and thus the rotational speed twice that of the crankshaft 1 is achieved. Thus, the left balancer shaft 13L is rotationally driven in the same direction as the crankshaft 1. The right balancer shaft 13R is rotationally driven in the opposite direction by the meshing of the helical gears 15.
[0014]
On both balancer shafts 13L and 13R, first and second journal portions 16a and 16b having a relatively small diameter are disposed in front of the helical gear 15, and third and fourth journal portions 16c and 16d having relatively large diameters are disposed at the rear thereof. Each is integrally formed. In addition, an eccentric weight part 17 is integrally formed at the rear part of each balancer shaft 13L and 13R, with the position of the center of gravity biased radially outward from the center of rotation and divided into two front and rear parts with the third journal part 16c interposed therebetween. Has been. That is, the third journal portion 16c is provided at the axial center of the two eccentric weight portions 17 arranged in series.
[0015]
Flange portions 18 having an enlarged diameter are formed at opposite ends of the front / rear eccentric weight portion 17 across the third journal portion 16c. Thrust receiving surfaces 19 are formed on the opposing end surfaces of the flange portions 18. As described above, if the flange portions 18 that receive the thrust load are provided at both axial ends of the third journal portion 16c, the lubricating oil is supplied by the thrust receiving surface 19 when the lubricating oil is supplied to the third journal portion 16c. Therefore, it can contribute to the improvement of the lubrication effect of the journal part.
[0016]
As shown in FIG. 4, the shaft portion 20 of the eccentric weight portion 17 has a relatively small diameter in order to obtain the expected equivalent rotational mass while making the eccentric weight portion 17 as small as possible. In order to compensate for the reduction in rigidity due to the reduced diameter, and to increase the rigidity of the thrust receiving surface 18 in the radial direction, the back surface of the thrust receiving surface 19 in the flange portion 18 provided on the front side of the third journal portion 16c, A rib 21 is provided between the mounting portion of the helical gear 15 and between the back surface of the thrust receiving surface 19 and the fourth journal portion 16d in the flange portion 18 provided on the rear side of the third journal portion 16c in the axial direction. The shaft 20 is provided in a portion extending over the entire length on the opposite weight side. As described above, if the ribs 21 are connected to both of the two flange portions 18 provided at both axial ends of the third journal portion 16c to which the largest load is applied, the rigidity of the journal portion is greatly enhanced. Therefore, it can contribute to the stable support of the balancer shafts 13L and 13R.
[0017]
As shown in FIG. 5, these ribs 21 may connect the outer peripheral edges of the corresponding journal part 16 and flange part 18 approximately linearly, but the weight increase due to the provision of the ribs 21. In order to minimize and optimize the stress distribution, as shown in FIG. 1 and FIG. 4, a taper shape in which the radial dimension of each eccentric weight portion 17 becomes smaller toward the center in the axial direction. Is preferred.
[0018]
On the other hand, the journal portions 16a to 16d of both the balancer shafts 13L and 13R are supported by two divided first to fourth bearing holes 22a to 22d formed by joining the upper and lower housings 14U and 14L to each other. Is done.
[0019]
The journal portions 16a to 16d of the balancer shafts 13L and 13R are respectively placed on the half of the bearing holes 22a to 22d on the side of the lower housing 14L, and in this state, the upper housing 14U side of the bearing holes 22a to 22d is placed. The upper and lower housings 14U and 14L are joined to each other by aligning the halved portion of the upper and lower housings 14a to 16d with the journal portions 16a to 16d of the balancer shafts 13L and 13R. It will be rotatably accommodated in 14L. The thrust receiving surface 19 contacts the front and rear end surfaces of the bearing wall 23c in which the third bearing hole 22c is formed to receive the thrust force.
[0020]
As shown in FIG. 3, the upper and lower housings 14U and 14L are each provided with a plurality of bolts B2 inserted from above at appropriate positions, and third and fourth bearing holes 22c and 22d. It is fastened by three bolts B3 that pass through the walls 23c and 23d and are inserted from below, and is loosened particularly at the portions of the bearing walls 23c and 23d where the radial acceleration due to the rotation of the eccentric weight portion 17 acts. It is considered that it becomes difficult to occur.
[0021]
A pump housing 24 provided with a trochoid lubricating oil pump (not shown) for pumping lubricating oil to various parts of the engine is bolted to the front end surface of the lower housing 14L. This lubricating oil pump (not shown) is provided at the shaft end of the right balancer shaft 13R, and when the right balancer shaft 13R rotates, an oil strainer 25 attached to the bottom wall of the lower housing 14L removes one of the lower housings 14L. The lubricating oil in the oil pan 5 is sucked through a tubular passage 26 provided in the side wall, and is pumped to various parts of the engine.
[0022]
The mounting boss 28 of the strainer cover 27 that holds the oil strainer 25 is integrally formed on the lower side of the two balancer shafts in the lower housing 14L, that is, on the lower position of the left balancer shaft 13L. The mounting boss 28 has a substantially cylindrical shape, and the bolt provided between the two balancer shafts 13L and 13R of the bolt B3 for fastening the upper housing 14U and the lower housing 14L to each other and the lower side thereof. The center of the left balancer shaft 13L is arranged between the bolts provided on the outer side of the left balancer shaft 13L, and the bearing wall 23c provided with a half portion of the third bearing hole 22c in the middle portion in the front-rear direction of the lower housing 14L The outer periphery is connected. Thus, the upper housing 14U and the lower housing 14L are fastened, and the rigidity of the bearing wall 23c to which the thrust force of the two balancer shafts 13L and 13R is applied is increased.
[0023]
A fastening boss 30 for inserting a fastening bolt B1 with respect to the lower block 3 is provided at a position adjacent to the side of the end portion of the tubular passage 26, which contributes to increasing the fastening rigidity of the balancing device 4 with respect to the lower block 3. is doing.
[0024]
The thickness of the ribs 21 connected to the flange portions 18 provided at both ends in the axial direction of the third journal portion 16c (the dimension in the direction perpendicular to the axis) is to suppress an increase in weight. It is preferable to minimize the thickness, and if the thickness of the rib 21 is made smaller than the thickness of the flange portion 18 (the dimension in the direction along the axis), the weight can be reduced, but the increase in rigidity and the suppression of the increase in weight are achieved. In order to achieve both, it is optimal that the thicknesses of the flange portion 18 and the rib 21 are approximately the same. Further, as shown in FIG. 6, if the rib 21 is connected to the outermost periphery of the flange portion 18, the rigidity of the flange portion 18 can be further increased.
[0025]
Furthermore, depending on the amount of displacement and the overall structure, there may be a desire to make the weights of the eccentric weight portions 17 on both sides of the third journal portion 16c different from each other. In such a case, the eccentric weight portion having a larger weight. Increasing the height and thickness of the ribs on the side is effective in increasing the strength on the side where the thrust load increases.
[0026]
【The invention's effect】
As described in detail above, conventionally, the portion on the anti-weight side of the thrust receiving surface formed on the flange portion that is larger than the diameter of the journal portion tends to lack rigidity because the outer peripheral side has a cantilever structure. there were. According to the invention of claim 1 of the present application, since the rib connected to the back surface of the thrust receiving surface in the flange portion on the anti-weight side and extending in the axial direction is provided, the rigidity of the thrust receiving surface is increased. be able to. Therefore, according to the present invention, it is possible to achieve a great effect on highly accurate thrust regulation. In particular, since the ribs are extended in the axial direction and the intermediate part in the axial direction is a valley, the weight distribution on the anti-weight side is suppressed by optimizing the stress distribution, and the journal parts of the eccentric weight part The rigidity between them can be further increased. That is, the shaft portion can be made thinner after obtaining the desired rotational inertial mass, which is effective in suppressing an increase in weight.
[Brief description of the drawings]
FIG. 1 is a front sectional view showing a part of an engine to which the present invention is applied. FIG. 2 is a side sectional view showing a part of an engine to which the invention is applied. FIG. 3 is a bottom view of the lower housing of the balancing device. FIG. 4 is a side view of the balancer shaft, partially cut away. FIG. 5 is a partial side view of another embodiment of the balancer shaft. Side view showing a part of another form of cut out [Explanation of symbols]
4 Balancer 13L / 13R Balancer shaft 16c Journal portion 17 Eccentric weight portion 18 Flange portion 19 Thrust receiving surface 21 Rib

Claims (1)

A balancer shaft of a balance device for an engine having a journal portion integrally formed with a flange portion having a thrust receiving surface larger in diameter than the journal portion so as to restrict the axial movement of the eccentric weight portion,
Two journal parts are provided at both axial ends of the eccentric weight part,
The flange portion is provided in one of the two journal portions,
The eccentric weight portion includes a shaft portion having a diameter smaller than the diameter of the journal portion, thereby forming end surfaces facing each other in the axial direction between the flange portion and the other journal portion,
Counter-weights side of the rib where the between each other said end face of the flange portion and the other of the journal portion is axially connected to and its axially intermediate portion is gradually decreased its height so that the valleys the eccentric weights section A balancer shaft of a balance device for an engine characterized by being extended.

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