JPH11101309A - Balancer device of internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the number of parts while improving the assembly property of a balance shaft. SOLUTION: This balancer device is composed of a balancer shaft 12 by which unbalance parts 12c, 12d are formed, a cylinder block 11 in which a balancer shaft chamber 13 in which the balancer shaft 12 is stored is formed, a helical gear 21 fitted to the shaft part of the balancer shaft 12 projected from the cylinder block 11 and to which the rotation drive force of the balancer shaft 12 is transmitted and a thrust plate 23, interposed between the helical gear 21 and the outer wall of the cylinder block 11, for positioning the balancer shaft 12, while receiving a thrust load generated by the rotation drive force transmitted to the helical gear 21. The helical gear 21 is integrally formed by including a gear part 21a and a nearly ring shape plate part 21b, positioned to the thrust plate 23 side of the gear part 21a, for increasing the contact area with the thrust plate 23 and pressed in and fixed to the shaft part of the balancer shaft 12.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a balancer device for reducing the vertical excitation force of an internal combustion engine, and more particularly to a technology for improving the assemblability of the device and reducing the number of parts.

[0002]

2. Description of the Related Art As a balancer device for an internal combustion engine, for example, there is one as shown in FIG. That is, the balancer device is provided with two balancer shafts 2a and 2b each of which is an unillustrated cylinder block and has an unbalanced portion substantially parallel to the crankshaft 1, and has a balancer rotation speed twice as high as that of the crankshaft 1. Shafts 2a, 2b
Are rotated in opposite directions to reduce the vertical excitation force of the internal combustion engine.

[0003] The balancer shafts 2a, 2b
For example, as shown in FIG. 9, is fitted into a balancer shaft chamber 4 formed in the cylinder block 3, and is positioned and fixed to the cylinder block 3 via a thrust plate 5. A helical gear (helical gear) 6 for transmitting the rotational driving force of the balancer shafts 2a and 2b is fitted to the shaft portions of the balancer shafts 2a and 2b protruding from the cylinder block 3, and the balancer shaft 2
The helical gear 6 is fixed by a washer 7 and a bolt 8 fastened to the ends of a and 2b.

[0004]

However, in the structure for mounting the balancer shafts 2a and 2b, the helical gear 6 is fixed by the washer 7 and the bolt 8, so that the balancer shafts 2a and 2b are not fixed. There has been a problem that the assembling work takes time and it is difficult to reduce the number of parts.

[0005] In order to drive the accessory directly by the balancer shaft 2a or 2b due to a request to reduce the number of parts of the internal combustion engine, the balancer shaft 2a
There is also a problem that it is impossible to fix the helical gear 6 with the washer 7 and the bolt 8 due to the configuration in which the auxiliary machine is attached to one end of the a and 2b. Accordingly, the present invention has been made in view of the above-described conventional problems, and has been changed in the shape and the fixing method of the helical gear to improve the assemblability of the balance shaft and reduce the number of parts in the internal combustion engine balancer device. The purpose is to provide.

As a prior art, there is Japanese Patent Application Laid-Open No. 8-4839 as to a balancer shaft, but only a single gear is disclosed as a drive gear.
It does not relate to the problem of the present application.

[0007]

According to a first aspect of the present invention, there is provided a balancer shaft having at least one unbalanced portion, and a storage portion in which the balancer shaft is rotatably supported and stored. A helical gear fitted to the shaft portion of the balancer shaft protruding from the holding member and transmitting the rotational driving force of the balancer shaft; and the helical gear and the outer wall of the holding member. A thrust plate interposed between the helical gears and positioning the balancer shaft while receiving a thrust load due to the rotational driving force transmitted to the helical gear. The bevel gear includes a gear portion and a substantially annular plate portion located on the thrust plate side of the gear portion and increasing a contact area with the thrust plate. It is formed, and configured to be press-fitted into the shaft portion of the balancer shaft.

According to this configuration, since the helical gear is fixed to the balancer shaft by press-fitting, there is no need for a washer and a fastening member such as a bolt for fixing the helical gear which are indispensable in the conventional balancer device. The number of parts and the number of assembling steps can be reduced.
In addition, since the helical gear is integrally formed with a plate portion that increases the contact area with the thrust plate, when driving the balancer shaft, a thrust load is applied from the helical gear in the thrust plate direction. Even if it acts, the surface pressure at such contact portions is reduced, and wear is reduced.

In the invention according to claim 2, the plate portion is formed to have substantially the same outer diameter as the gear portion. According to this configuration, the gear portion is formed on the outer periphery of the substantially cylindrical cylindrical member, for example, by cold forging, and then the outer peripheral portion of the cylindrical member and one end of the gear portion are cut to form a gear. The part and the plate part are easily formed integrally.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail with reference to the attached drawings. 1 to 6 show one embodiment of a balancer device for an internal combustion engine according to the present invention. As shown in FIG. 1, a balancer shaft chamber 13 (housing) into which a balancer shaft 12 is inserted is disposed in a cylinder block 11 (holding member) of the internal combustion engine 10 at a position above and below a crankshaft (not shown) and substantially parallel to the crankshaft. Parts) are respectively formed. The balancer shaft chamber 13 has a first bearing portion 14 that axially supports the balancer shaft 12 at an opening and a back portion thereof.
And the second bearing portion 15 are respectively formed. In order to supply lubricating oil to the first bearing portion 14 and the second bearing portion 15,
From the oil gallery 16 to the bearing 17 of the crankshaft
A second lubricating oil supply passage 19 is formed substantially in the horizontal direction of the cylinder block 11 so as to intersect with the first lubricating oil supply passage 18 that supplies the lubricating oil to the cylinder block 11. The second lubricating oil supply passage 19
Can be easily formed by drilling the cylinder block 11 with a drill or the like and then closing both ends of the cylinder block 11 with blind plugs 20, respectively.

As shown in FIGS. 2 and 3, the balancer shaft 12 is provided with a first bearing portion 14 of a balancer shaft chamber 13.
The first journal portion 12a supported by the first journal portion, the second journal portion 12b supported by the second bearing portion 15 of the balancer shaft chamber 13, and the cross-section provided at both ends of the second journal portion 12b are substantially semicircular. Unbalance part 12c, 1
2d. Further, a shaft portion 12e to which a helical gear (helical gear) 21 described later is fitted is attached to an end of the balancer shaft 12 on the first journal portion 12a side.
A key groove 12f is formed in the balancer shaft 12 in which a key 22 for positioning the helical gear 21 is fitted. Further, a connecting portion between the shaft portion 12e and the first journal portion 12a has a stepped portion 12g into which a thrust plate 23 to be described later is fitted, and a substantially annular contact that abuts one side surface of the thrust plate 23. Part 12h
Is formed. The outer diameter of the contact portion 12h is formed to be substantially the same as the outer diameter of the helical gear 21 described later.

As shown in FIG. 4, the helical gear 21 is formed to include a gear portion 21a formed in a winding with helical teeth and an annular plate portion 21b. The helical gear 21 is, as shown in FIG.
After the gear portion 21a is formed by cold forging on the outer circumference of approximately 4 and substantially half of the axial length (see FIG. 5A), the end portion A of the gear portion 21a is an intermediate portion of the cylindrical member 24. By cutting, the gear portion 21a and the plate portion 21b are integrally formed (see FIG. 5B). Therefore, the gear portion 21a and the plate portion 21b have substantially the same outer diameter. A key groove 21c into which the key 22 fits is provided on the inner periphery of the helical gear 21, that is, the inner periphery of the cylindrical member 24.
Is formed.

As shown in FIG. 6, the thrust plate 23 has a substantially rhombic shape with rounded corners, and an insertion hole 23a through which the stepped portion 12g of the balancer shaft 12 is inserted is formed at the center. The insertion hole 23a is formed at an inner diameter having a predetermined space between the insertion hole 23a and the stepped portion 12g of the balancer shaft 12, and the sliding resistance is reduced by lubricating oil supplied at the space. Further, chamfered portions 23b of a predetermined size are formed at both ends of the insertion hole 23a of the thrust plate 23, and function as oil reservoirs for lubricating oil. Further, bolts 2 for fixing the thrust plate 23 to the cylinder block 11 are provided at both ends of the long axis of the thrust plate 23.
Bolt through holes 23c through which the holes 5 pass are formed.

Next, the operation of the balancer device having such a configuration will be described. When assembling the balancer device of the internal combustion engine, the first bearing 1 of the balancer shaft chamber 13 is used.
The metal bush 26 is press-fitted into the fourth and second bearing portions 15 using a jig. On the other hand, the balancer shaft 12 has
After the thrust plate 23 is fitted into the stepped portion 12g and the key 22 is fitted into the key groove 12f of the shaft portion 12e, the helical gear 21 is pressed into the shaft portion 12e. That is, the helical gear 21 is not fixed by a washer and a bolt as in the related art, but is fixed by press-fitting. Then, the balancer shaft 12 is fitted into the balancer shaft chamber 13 through the opening of the balancer shaft chamber 13, and the thrust plate 23 is inserted.
The balancer shaft 12 is rotatably fixed while being positioned with respect to the cylinder block 11 by the bolt 25 inserted into the bolt through hole 23c.

The helical gear 21 fitted to the balancer shaft 12 receives a rotational driving force from the crankshaft via a gear or the like, and the balancer shaft 12 is rotated at twice the rotational speed of the crankshaft. It rotates in the opposite direction, and the vertical excitation force of the internal combustion engine is reduced. When the internal combustion engine 10 is in an accelerating state, the gear to which the rotational driving force of the balancer shaft 12 is transmitted is the helical gear 21. For example, a thrust load acts on the balancer shaft 12 in the direction of the thrust plate 23. I do. At this time, since the plate portion 21b is formed integrally with the helical gear 21, the contact area between the helical gear 21 and the thrust plate 23 increases, and the surface pressure decreases. Therefore, the wear of the contact portion between the helical gear 21 and the thrust plate 23 is reduced, and the life of the balancer device can be extended. On the other hand, when the internal combustion engine 10 is in the deceleration state, for example, the helical gear 21
Thrust load acts in the direction. At this time, as shown in FIG. 2 and FIG.
Since h is formed, the contact area between the balancer shaft 12 and the thrust plate 23 increases, and the surface pressure decreases. Therefore, as in the case of the acceleration state, the wear of the contact portion between the balancer shaft 12 and the thrust plate 23 is reduced, and the life of the balancer device can be extended.

FIG. 7 shows another embodiment of the balancer device for an internal combustion engine according to the present invention. That is, in the present embodiment, in order to reduce the number of parts of the internal combustion engine, in order to directly drive an auxiliary device (for example, a vacuum pump) by the balancer shaft 12, the shaft portion 12e of the balancer shaft 12 is extended and the tip portion is extended. A male screw portion 12k to which an auxiliary machine is fixed is formed. In the conventional configuration, the helical gear 21 was fixed by the washer and the bolt, so that the shaft portion 12e of the balancer shaft 12 could not be extended. However, according to the configuration of the present embodiment, the helical gear 21 Since 21 is fixed to the shaft portion 12e of the balancer shaft 12 by press fitting, the shaft portion 12e of the balancer shaft 12 can be extended, and the number of parts of the internal combustion engine can be reduced.

According to the balancer device for an internal combustion engine described above, the helical gear 21 is fixed to the balancer shaft 12 by press fitting, so that a washer and a bolt for fixing the helical gear 21 can be eliminated. Thus, the number of parts and the number of assembling steps can be reduced. Further, since the helical gear 21 is integrally formed with a plate portion 21b for increasing the contact area with the thrust plate 23, a thrust load acts on the helical gear 21 in the direction of the thrust plate 23. Also, the contact pressure at the contact portion is reduced, and the wear is reduced. Therefore, the life of the balancer device can be extended.

[0018]

As described above, according to the first aspect of the present invention, since the helical gear to which the rotational driving force of the balancer shaft is transmitted is fixed by press-fitting, the number of parts is reduced and the number of assembling steps is reduced. Can be reduced. In addition, the plate portion integrally formed with the helical gear reduces the surface pressure at the contact portion between the helical gear and the thrust plate, thereby reducing wear and extending the life of the balancer device.

According to the second aspect of the present invention, since the helical gear having the plate portion is manufactured by cutting the cylindrical member after cold forging, the manufacturing cost of the helical gear is reduced. can do.

[Brief description of the drawings]

FIG. 1 shows an embodiment of a balancer device of the present invention,
(A) is a right side sectional view, (B) is a front view.

FIG. 2 is a configuration diagram of a balancer device according to the first embodiment;

FIG. 3 is a detailed view of the balancer shaft according to the first embodiment;

FIG. 4 shows details of the helical gear, in which (A) is a side sectional view and (B) is a front view.

FIG. 5 illustrates a method of manufacturing the helical gear,
(A) is a sectional view immediately after cold forging, and (B) is a sectional view of the final shape.

FIG. 6 shows details of the thrust plate according to the first embodiment;
(A) is a front view, (B) is an AA cross-sectional view in (A).

FIG. 7 is a detailed view of a balancer shaft used in another embodiment of the balancer device of the present invention.

FIG. 8 is a schematic explanatory view of a conventional balancer device.

FIG. 9 is a detailed explanatory view of a conventional balancer device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Internal combustion engine 11 Cylinder block 12 Balancer shaft 12c, 12d Unbalance part 12e Shaft part 13 Balancer shaft chamber 21 Helical gear 21a Gear part 21b Plate part 23 Thrust plate

Claims (2)

[Claims] 1. A balancer shaft having at least one unbalanced portion, a holding member having a storage portion in which the balancer shaft is rotatably supported and stored, and a balancer protruding from the holding member. A helical gear fitted to the shaft portion of the shaft and transmitting the rotational driving force of the balancer shaft, and interposed between the helical gear and the outer wall of the holding member, and transmitted to the helical gear. A thrust plate for positioning the balancer shaft while receiving a thrust load due to the rotational driving force, wherein the helical gear includes a gear portion, and a thrust plate side of the gear portion. And a substantially annular plate portion that increases the contact area with the thrust plate, and is press-fitted and fixed to the shaft portion of the balancer shaft. A balancer device for an internal combustion engine. 2. The balancer device for an internal combustion engine according to claim 1, wherein said plate portion has substantially the same outer diameter as said gear portion.