JP2008144971A - Engine balancer shaft supporting structure - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an engine balancer shaft supporting structure for improving the durability of a balancer and the degree of freedom in designing it without increasing the size of an engine and the number of components. <P>SOLUTION: A casing for receiving a pair of balancer shafts at the lower side of a cylinder block consists of upper and lower side split casings. An oil pump body is formed integrally with one of them. Both balancer shaft are each inserted at one end into the oil pump body. Both balancer shafts are supported at their intermediates or other ends on a two-split bearing provided between both casings. Thus, the oil pump body can be formed integrally with the casing. This reduces the number of components and assembling manhours, makes a journal portion thinner than other portions because one bearing is split in two, reduces sliding resistance, reduces the size and weight of the casing, and improves the degree of freedom in designing the balancer shafts. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an engine in which a balancer shaft is disposed below a cylinder block, and more particularly to a support structure for the balancer shaft.

  Conventionally, there is an engine in which a balancer is disposed below a cylinder block (for example, see Patent Document 1). In such an engine, the balancer is composed of a pair of balancer shafts supported by a casing provided in an oil pan below the cylinder block. The balancer shafts are geared to each other and chained to one balancer shaft. A driving force is transmitted from the crankshaft through the like, and the balancer shafts rotate in opposite directions at a rotational speed twice that of the crankshaft.

On the other hand, in the above structure, the oil pump is also arranged close to the balancer below the engine in order to reduce the size of the engine. Therefore, the balancer casing and the oil pump body may be integrated.
JP 63-106443 A

  The balancer shaft is generally supported at a plurality of locations. However, if the journal portion pivotally supported by the bearing of the balancer shaft has a large diameter, the sliding contact speed increases during rotation, and the bearing and the journal portion are Since it becomes easy to wear, it is preferable that the diameter of the journal portion is as small as possible within a range in which the strength can be secured.

  However, as disclosed in JP-A-9-210135, for example, when the balancer shaft is inserted from its axial direction, at least the journal portion needs to have the largest diameter.

Therefore, for example, it is conceivable to divide the bearing of the casing and the balancer shaft into upper and lower parts. However, if the whole part is divided into two parts, the oil pump body cannot be integrally formed with the casing. In addition, there is a problem that the number of assembly steps increases.
On the other hand, after assembling each part such as both the casing including the oil pump body and the oil pump cap into a sub-assembly, if the mounting surface to the cylinder block is machined, its workability will be reduced. Although it is desirable to machine the mounting surface, the machining error tends to occur, and in some cases, the balancer shaft is inclined, causing uneven wear.

  The present invention has been made in view of the problems of the prior art as described above, and is an engine balancer capable of improving the durability and design freedom of the balancer without increasing the size of the engine and increasing the number of parts. A first object is to provide a shaft support structure, and a second object is to provide an engine balancer shaft support structure that can prevent uneven wear of the balancer shaft without deteriorating assembly workability.

  According to the present invention, an upper casing and a lower casing in which the casing is vertically split in an engine in which a casing configured to receive a pair of balancer shafts is disposed below the cylinder block. An oil pump body is integrally formed in one of the upper casing and the lower casing, and one end of the balancer shafts is inserted into and supported by the oil pump body, or an intermediate portion of the balancer shafts or This is achieved by providing a balancer shaft support structure for an engine, characterized in that the other end portion is supported by a two-part bearing provided between the two casings. In this way, the oil pump body can be integrally formed with the casing, and since one bearing is divided into two parts, the journal portion can be made narrower as long as the strength can be ensured compared to the other portions.

  Also. The second object is to form an oil pump body integrally with the lower casing, fasten the upper casing and the lower casing to the cylinder block with first fastening means, and the oil pump body in the oil pump body. This is achieved by fastening the oil pump cap attached from the side opposite to the upper casing to the cylinder block by the second fastening means. As a result, the distance between the first and second fastening means can be made as long as possible, and errors can be easily absorbed.

  According to the balancer shaft support structure of an engine according to the present invention, a casing formed by receiving a pair of balancer shafts below a cylinder block is composed of an upper casing and a lower casing that are vertically split, and one of these upper and lower casings. The oil pump body is integrally formed with the oil pump body, and one end of both balancer shafts is inserted into and supported by the oil pump body, and the middle part or the other end part of both balancer shafts is attached to the split bearing provided between the two casings. By adopting a supporting structure, the oil pump body can be integrally molded with the casing, reducing the number of parts and assembly man-hours, and because one of the bearings is divided into two, the journal can be secured within a range that can ensure strength compared to the other parts. The part can be made thinner, the sliding resistance can be reduced, and the Size and weight of the bedding is possible. Moreover, the design freedom of the balancer shaft is improved. Also, the oil pump body is integrally formed in the lower casing, the upper casing and the lower casing are fastened to the cylinder block by the first fastening means, and the oil attached from the side opposite to the upper casing in the oil pump body By fastening the pump cap to the cylinder block with the second fastening means, the distance between the first and second fastening means can be made as long as possible, and each attachment of the upper casing and the oil pump cap to the cylinder block It becomes easy to absorb surface processing errors.

  Preferred embodiments of the present invention will be described below in detail with reference to the accompanying drawings.

  FIG. 1 is a longitudinal sectional view of an essential part of the engine, and FIG. 2 is a sectional view taken along line II-II in FIG. The engine E is an in-line four-cylinder engine in which four cylinders are arranged in a substantially vertical direction and the crankshaft 1 is arranged in a horizontal direction. The engine body includes a cylinder head 2, a cylinder block 3 coupled to the lower surface of the cylinder head 2, a lower block 4 coupled to the lower surface of the cylinder block 3, and an oil pan 5 coupled to the lower surface of the lower block 4. It has. The journal portion of the crankshaft 1 is rotatably supported by a two-part bearing formed between the cylinder block 3 and the lower block 4.

  On the lower surface of the lower block 4, a secondary balancer device 6 for reducing secondary vibration of the engine E and an oil pump 7 composed of a trochoid pump are integrally provided.

  The secondary balancer device 6 includes a pair of balancer shafts 8 and 9, and an upper casing 10 a and a lower casing 10 b that support and receive the balancer shafts 8 and 9. The balancer shafts 8 and 9 are connected to each other by gears 11a and 11b, and via a sprocket 12 provided at one end of one balancer shaft 8, an endless chain 13 and a sprocket 14 provided at one end of the crankshaft 1. Driving force is transmitted from the crankshaft 1 so that the balancer shafts 8 and 9 rotate in opposite directions at a rotational speed twice that of the crankshaft 1.

  The balancer shafts 8 and 9 are provided with first journal portions 8a and 9a and second journal portions 8b and 9b having relatively small diameters near one end and near the other end. Further, balancer weights 8c, 8d, 9c, and 9d that are divided into two in the axial direction by the second journal portions 8b and 9b are provided on the other end sides of the balancer shafts 8 and 9, respectively.

  Here, the bearings 16 and 17 of the first journal portions 8a and 9a are formed in a hole shape in an oil pump body 7a described later that is integrated with the lower casing 10b. Further, the bearings 18 and 19 of the second journal portions 8b and 9b provided at the intermediate portions of the balancer shafts 8 and 9 are divided into two parts formed by aligning the upper casing 10a and the lower casing 10b. It is a metal bearing. Thus, when the balancer shafts 8 and 9 are received in the upper casing 10a and the lower casing 10b, one end side of each balancer shaft 8 and 9 is inserted into the bearings 16 and 17 of the lower casing 10b and the bearing 18 , 19 can be placed in the lower casing 10b side halved portion, and the upper casing 10a can be aligned and assembled, so that each journal portion 8a, 9a, 8b, 9b can be thinned in a range that can ensure its strength, The sliding resistance between each journal portion 8a, 9a, 8b, 9b and each bearing 16-19 can be reduced, and the casing can be made smaller and lighter. In addition, you may form the 2nd journal part 8b, 9b in the other end part of each balancer shaft 8,9.

  As shown in FIG. 3, the upper casing 10a and the lower casing 10b assembled to each other are fastened to the lower block 4 by through bolts 20 and 21 as first fastening means. At this time, as shown in FIG. 4, if the upper casing 10a and the lower casing 10b are directly fastened to the lower block 4 with the bolts 20 and 21, the number of parts and the number of assembling steps can be reduced.

  5, FIG. 7 which expanded the principal part, FIG. 8 which looked at the IIX-IIX line of FIG. 7, and FIG. 9 which looked at the IX-IX line of FIG. 7, gear 11a, 11b of the upper casing 10a The portions covering the shaft form thrust bearings 22 and 23, which are in contact with both end surfaces in the axial direction of the gear 11a integrated with the balancer shaft 8. The portions of the upper casing 10a covering the gears 11a and 11b bulge outward, particularly upward, and oil passages 24 and 25 communicating with the upper surface (outer surface) of the upper casing 10a are provided on the front and rear surfaces of the bulged portion. Yes. A rib 10c extending in the front-rear direction is formed on the outer surface of the upper casing 10a that communicates with the oil passages 24, 25 so as to cover the periphery of the upper casing 10a. The oil that has entered the pool is guided to the oil passages 24 and 25, and is preferably supplied to the gears 11a and 11b and the thrust bearings 22 and 23. Further, it goes without saying that the rigidity of the upper casing 10a is improved by the rib 10c. In particular, as shown in FIG. 5, a bulging portion covering the gears 11a and 11b of the upper casing 10a and a balancer weight 8c. , 8d, 9c, and 9d are provided with ribs 10c between the bulging portions, and the rigidity thereof is remarkably improved.

  On the other hand, as shown well in FIG. 7, a rib 7f similar to the above is also formed on the upper surface of an oil pump body 7a described later. Accordingly, the oil that has entered between the ribs 7 f, that is, the oil sump, is also supplied to the thrust bearings 22 and 23 through the upper surface of the upper casing 10 a and the oil passage 24. Here, the upper surface of the oil pump body 7a, that is, the bottom surface of the oil reservoir, is higher by H than the upper surface of the upper casing 10a adjacent thereto, that is, the bottom surface of the oil reservoir. Therefore, oil can be sufficiently supplied to the thrust bearings 22 and 23 even if there is some assembling error.

  As well shown in FIGS. 5, 6, and 10, an oil pump body 7a of the oil pump 7 is integrally formed in the lower casing 10b. One end of the other balancer shaft 9 enters the pump chamber 7b of the oil pump body 7a, and an inner rotor 7c of the trochoid pump is attached. A combination of the inner rotor 7c and the outer rotor 7d aligns the pump cap 7e and assembles the pump chamber 7b and a part of the oil passage. The pump cap 7e is fastened to the lower block 4 with a bolt as second fastening means (not shown). As a result, the secondary balancer device 6 and the oil pump 7 are fixed to the lower block 4 together with the through bolts 20 and 21 as the first fastening means. Thereby, compared with the case where it fastens only with the casing of the secondary balancer apparatus 6, fastening parts can be separated, and the error of the processing accuracy of the attachment surface to the lower block 4 (cylinder block) has both balancer shafts. 8 and 9 can be absorbed to the extent that they do not affect.

  In this state, the inner rotor 7c actually cooperates with the outer rotor 7d to suck up the oil in the oil pan 5 from the oil strainer 27 provided at the lower portion of the lower casing 10b through the oil introduction passage 28, and supply it to each part of the engine. To come.

  Here, as well shown in FIGS. 6 and 8 to 10, an oil introduction passage 28 extending from the oil strainer 27 to the pump chamber 7 b is formed integrally with the lower casing 10 b at the lower end thereof. The casing 10b is reinforced. The oil introduction passage 28 extends between the balancer shaft 8 and the balancer shaft 9 substantially in parallel with the axial direction thereof, and does not bulge downward by entering between the balancer shafts 8, 9. It has become.

  The balancer shaft 8 and the balancer shaft 9, that is, between the balancer shafts 8 and 9, is the largest diameter portion of the balancer shafts 8, 9, that is, balancer weights 8 c, 8 d, 9 c, 9 d. This means that a part of the oil introduction passage 28 is disposed above the common tangent line Lh to the rotation trajectory, that is, on the axial center side of the balancer shafts 8 and 9. The same applies between the gears 11a and 11b.

  As shown in FIG. 8, the oil introduction passage 28 is defined by expanding the bottom wall of the lower casing 10 b to the side between the balancer shafts 8 and 9 and the bottom side of the oil pan 5. Therefore, not only the downward bulge is suppressed, but the lower bulge portion touches the oil level Lo of the oil pan 5, thereby preventing the oil level Lo from being blown out.

  On the other hand, as shown well in FIG. 11, upward openings 30 and 31 are provided between the upper casing 10a and the lower casing 10b at portions where the balancer weights 8c, 8d, 9c and 9d are located. Accordingly, as the balancer shafts 8 and 9 rotate, the balancer weights 8c, 8d, 9c and 9d scrape the oil accumulated at the bottom of the lower casing 10b from the openings 30 and 31 to the outside. Further, the upper portions of the openings 30 and 31 are covered with protrusions 32 and 33 serving also as reinforcing ribs with a gap, thereby preventing unnecessary oil from entering from the engine E main body side.

  As is apparent from the above description, the engine balancer shaft support structure according to the present invention comprises an upper casing and a lower casing in which a casing formed by receiving a pair of balancer shafts below the cylinder block is vertically split. An oil pump body is integrally formed in either the upper or lower casing, and one end of both balancer shafts is inserted into and supported by the oil pump body, and both balancers are mounted on a split bearing provided between the two casings. By adopting a structure that supports the middle or other end of the shaft, the oil pump body can be integrally formed with the casing, reducing the number of parts and assembly man-hours. The journal part can be made thin as long as the strength can be secured, and the sliding resistance can be reduced. It is possible to fence, becomes possible size and weight of the casing. Moreover, the design freedom of the balancer shaft is improved. Also, the oil pump body is integrally formed in the lower casing, the upper casing and the lower casing are fastened to the cylinder block by the first fastening means, and the oil attached from the side opposite to the upper casing in the oil pump body By fastening the pump cap to the cylinder block with the second fastening means, the distance between the first and second fastening means can be made as long as possible, and each attachment of the upper casing and the oil pump cap to the cylinder block It becomes easy to absorb surface processing errors.

The principal part longitudinal cross-sectional view of an engine. Sectional drawing seen about the II-II line | wire of FIG. Sectional drawing seen about the III-III line of FIG. The figure similar to FIG. 3 which shows the modification of this embodiment. Sectional drawing seen about the VV line | wire of FIG. The bottom view of the secondary balancer apparatus with which this invention was applied. The principal part enlarged view of FIG. Sectional drawing seen about the IIX-IIX line | wire of FIG. Sectional drawing seen about the IX-IX line of FIG. Sectional drawing seen about the XX line of FIG. Sectional drawing seen about the XI-XI line of FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Crankshaft 2 Cylinder head 3 Cylinder block 4 Lower block 5 Oil pan 6 Secondary balancer device 7 Oil pump 7a Oil pump body 7b Pump chamber 7c Inner rotor 7d Outer rotor 7e Pump cap 7f Ribs 8, 9 Balancer shafts 8a, 9a First journal Portion 8b, 9b second journal portion 8c, 8d, 9c, 9d balancer weight 10a upper casing 10b lower casing 10c rib 11a, 11b gear 12 sprocket 13 endless chain 14 sprocket 16, 17 bearing 18, 19 bearing 20, 21 through bolt 22, 23 Thrust bearings 24, 25 Oil passage 27 Oil strainer 28 Oil introduction passage 30, 31 Opening 32, 33 Projection E Engine

Claims (1)

In an engine in which a casing configured to receive a pair of balancer shafts is disposed below a cylinder block,
The upper casing and the lower casing are divided into upper and lower casings, and an oil pump body is integrally formed on either the upper casing or the lower casing,
One end of both the balancer shafts is inserted into and supported by the oil pump body,
A balancer shaft support structure for an engine, characterized in that an intermediate portion or the other end portion of both balancer shafts is supported by a split bearing provided between the casings.

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