JPH0765638B2 - Engine balancer shaft drive structure - Google Patents

Description

TECHNICAL FIELD The present invention relates to a balancer shaft drive structure for an engine,
In particular, it relates to measures to make the engine compact.

(Prior Art) Generally, as a balancer device for an engine, a balancer shaft having an unbalanced portion is arranged in a cylinder block, and the balancer shaft is rotated at the same rotation speed as the crankshaft or at an integral multiple of two or more. By rotating the crankshaft in synchronism with the rotation of the crankshaft, the unbalance between the primary and secondary couples and inertial forces generated by the reciprocating motion of each piston is suppressed by the centrifugal force acting on the unbalanced portion. It is known to do so. In order to drive the balancer shaft in such an engine, there is a conventional method, for example, Japanese Patent Laid-Open No.
As disclosed in the publication, a drive gear is provided at the end of the crankshaft outside the cylinder block, a driven gear that meshes with the drive gear is provided at the end of the balancer shaft, and the balancer shaft is driven by the crankshaft. Things are known.

(Problems to be Solved by the Invention) However, in such an engine, since the balancer shaft and the crankshaft are meshed with each other outside the cylinder block, there is a problem that the total length of the engine is increased by this gear. .

When assembling the balancer shaft to the cylinder block, a method of inserting the balancer shaft from the end wall of the cylinder block or a method of assembling the balancer shaft by lifting it from the opening at the lower end of the cylinder block can be considered. A method of assembling the balancer shaft more easily than the method is desired.

By the way, in general, when a crankshaft is arranged in a cylinder block, a journal portion of the crankshaft is rotatably supported by a plurality of main bearing portions provided in a lower portion of the cylinder block and a main bearing cap attached to each main bearing portion. Supporting is done. However, it is necessary to increase the support rigidity of the crankshaft as much as possible from the viewpoint of suppressing engine vibration. Therefore, it is conceivable that a lower block is provided below the cylinder block and the main bearing caps are integrally formed on the lower block to improve the support rigidity of the crankshaft.

In this case, in order to process the oil that flows out from the lower block end wall side of the outermost main bearing cap portion provided at the position closest to the end wall of the lower block in each main bearing cap portion of the lower block, that is, the end flow oil, It is necessary to provide an oil return space between the outermost main bearing cap portion and the end wall, and return the end flow oil to the oil pan via this oil return space.

The present invention has been made in view of the above point, and its purpose is to presume an engine in which a lower block is arranged below a cylinder block, and to utilize the oil return space of the lower block to balance the balancer. An object of the present invention is to provide a balancer shaft drive structure that prevents the total length of the engine from becoming long by engaging the shaft with the crankshaft and gears and is excellent in the assemblability of the balancer shaft.

(Means for Solving the Problems) In order to achieve the above object, in the present invention, a balancer shaft is arranged on a dividing surface between a cylinder block and a lower block, and a drive gear and a driven gear are provided in the oil return space of the lower block. Is to arrange.

Specifically, the solution means taken by the present invention is to dispose a lower block integrally formed with a plurality of main bearing cap portions for rotatably supporting a crankshaft below the cylinder block. A balancer shaft rotatably supported by each of the main bearing caps is arranged in parallel with the crankshaft between the block and the lower block, and is provided on the drive gear and the balancer shaft provided on the crankshaft. The driven gear is an oil return space formed by one end wall of the lower block and an outermost main bearing cap portion located closest to the one end wall of the main bearing cap portions of the lower block. Are engaged with each other.

(Operation) With the above configuration, in the present invention, the endmost main bearing cap portion located closest to one end wall of the lower block among the main bearing cap portions of the lower block and the one end wall of the lower block. Since the drive gear and the driven gear are respectively provided on the crankshaft and the balancer shaft in the oil return space formed between and, the crankshaft and the balancer shaft do not become long by providing the drive gear and the driven gear, It is possible to prevent the total length of the engine from increasing.

Further, since the balancer shaft is arranged between the cylinder block and the lower block and the lower block is fixed to the cylinder block, the balancer shaft can be easily assembled.

(Example) Hereinafter, the Example of this invention is described based on drawing.

1 to 11 show an engine having a balancer shaft drive structure according to an embodiment of the present invention. 1 to 11, reference numeral 1 denotes a cylinder block, the lower surface of the cylinder block 1 is open, a plurality of cylinders 3, 3 ... Each has a piston (not shown) inserted therein. A lower block 2 is arranged below the cylinder block 1 and is fastened to the cylinder block 1 with bolts. The lower block 2 is formed in the shape of a frame whose upper and lower surfaces are open, and a crank chamber 4 is formed inside the lower portion of the cylinder block 1 and inside the lower block 2. An oil pan 5 is provided below the lower block 2.
Is provided. That is, as shown in FIG. 3, front and rear end walls 2a, 2b and left and right side walls 2c, 2d of the lower block 2 are shown.
Each of the lower end surfaces of the oil pan rail portion 6 is formed into a continuous strip-shaped oil pan rail portion 6, and a flange portion 5a formed at the opening peripheral edge of the oil pan 5 is fastened to the oil pan rail portion 6 with a bolt. ing. Then, on the side of the rear end walls 1b, 2b of the cylinder block 1 and the lower block 2,
The cylinder block 3 is provided with a flange 7 for connecting the clutch housing.

Further, a crankshaft 8 and a balancer shaft 9 having an unbalanced portion are arranged in parallel to each other on the dividing surface of the cylinder block 1 and the lower block 2. As shown in FIG. A drive gear 10 is provided at the rear end portion of 8. On the other hand, a driven gear 11 meshing with the drive gear 10 is provided at the rear end of the balancer shaft 9.
Is provided, and the balancer shaft 9 is driven by the crankshaft 8 so as to rotate synchronously at a rotational speed twice as high as that of the crankshaft 8. The centrifugal force acting on the balance part is used to suppress it.

As shown in FIG. 5, the cylinder block 1 is integrally formed with a plurality of (two in the figure) partition walls 12 and 13 connecting the both side walls so as to partition the crank chamber 4 between the cylinders 3. And the rear end wall 1b of the cylinder block 1
Similarly, a partition wall 14 is integrally formed on the front side of the partition wall.
Semi-circular main bearing portions 15 are formed at the lower ends of 12 to 14 and at the inner side of the lower end of the front end wall 1a of the cylinder block 1, respectively. On the other hand, as shown in FIG. 4, the lower block 2 is located at a position corresponding to each main bearing portion 15, that is, below the cylinders 3, 3 and on the inner side of the front and rear end walls 2a, 2b of the lower block 2. Four main bearing cap portions 16 that connect the both side walls 2c and 2d are integrally formed to the lower block 2, and each main bearing portion 15 of the cylinder block 1 and each main bearing cap portion 16 of the lower block 2 are formed. The journals of the crankshaft 8 are rotatably supported by and
The support rigidity of the crankshaft 8 is improved by integrally forming each main bearing cap portion 16 on the lower block 2. Further, bearing parts 17, 17 for pivotally supporting the balancer shaft 9 are provided outside the left side wall 2c of the lower block 2 on the side of the main bearing cap part 16 supporting the middle part and the rear end part of the crankshaft 8.
The bearing blocks 17 and 17 are formed to straddle the cylinder block 1 and the lower block 2, respectively, and rotatably support the journal portions of the balancer shaft 9. Therefore, the crankshaft journal part on the front side of the drive gear 10 is pivotally supported by the main bearing of the partition wall 14 at the rear end, and the balancer shaft journal part on the front side of the driven gear 11 is pivotally supported by the bearing part 17 of the partition wall 14 at the rear end. The cylinder block rear end partition 14 and the lower block 2
Formed between the rear end wall 1b of the rear end wall 1b and the rear end wall 2b of the cylinder block and the rearmost end main bearing cap portion 16a located closest to the lower end wall 2b of the lower block. In the oil return space 18, the drive gear 10 and the driven gear 11 are made to mesh with each other.

Then, as shown in FIGS. 3 and 6, the front-rear intermediate portion of the oil pan rail portion 6 at the lower end of the left side wall 2c of the lower block 2, that is, the portion corresponding to the lower portion of the balancer shaft 9 is expanded outward. It is formed on the protruding portion 20 that protrudes.

Further, as shown in FIG. 1, the left side wall 2c of the lower block 2 is
Has one end connected to the front bearing portion 17 of the balancer shaft 9 and the other end connected to the front portion of the bulging portion 20.
A vertical wall 21 that connects the to the bulging portion 20 is provided.

Further, one end of the left side wall 2c is the balancer shaft 9
A lateral wall 22 is provided which is connected to the rear bearing portion 17 and the other end of which is connected to the flange 7 of the cylinder block 1 to connect the bearing portion 17 to the flange 7.

In addition, as shown in FIGS. 1, 3, and 6, two main bearing cap portions 16, 1 for supporting the intermediate portion of the crankshaft 8 in the bulging portion 20 of the lower block 2 are provided.
Mount bosses 23, 23 ... For mounting the engine mount are formed outside the portion where 6 is connected.

As shown in FIG. 7, the partition wall 12 on the front side and the corresponding main bearing cap portion 16 have the partition wall 12
Balance holes 24, 25 are formed to connect the crank chambers 4 on both sides so that pressure fluctuations in the crank chambers 4 on both sides of the partition wall 12 are mutually relaxed. Each balance hole
24 and 25 are formed in a substantially circular shape centering on the mating surface of the partition wall 12 and the main bearing cap portion 16.

As shown in FIGS. 4 and 7, one end of the main bearing cap portion 16 communicates with the lubrication surface of the main bearing cap portion 16 and the other end communicates with the bearing portion 17 of the balancer shaft 9. A main gallery 28 of the cylinder block 1 is formed on the lubrication surface of the main bearing cap portion 16 via an oil passage 27.
The oil is supplied from the above, and this oil is supplied to the bearing portion 17 of the balancer shaft 9 through the oil passage 26 to lubricate the bearing portion 17.

Further, as shown in FIG. 4 and FIG.
14 and corresponding rearmost main bearing cap
On the mating surface with 16a, an oil groove 29 is formed, one end of which communicates with the lubrication surface of the last main bearing cap portion 16a and the other end of which communicates with the bearing 17 of the balancer shaft 12 Oil is supplied to the lubrication surface of the bearing cap portion 16a from the main gallery 28 via an oil passage 30, and this oil is supplied to the bearing portion 17 of the balancer shaft 9 via the oil groove 29 to The part 17 is lubricated.

Further, as shown in FIGS. 9 and 10, below the driven gear 11 in the oil return space 18 between the lower block rear end wall 2b and the rearmost main bearing cap portion 16a, the driven gear 11 is A lateral wall 31 having an arcuate shape along the addendum circle and connecting the lower block rear end wall 2b and the rearmost end main bearing cap portion 16a is formed, and the upper surface of the lateral wall 31 is a concave circle. It is curved in an arc shape and is formed in the oil sump portion 32 for accommodating the end flow oil discharged from the balancer shaft bearing portion 17 of the rearmost main bearing cap portion 16a.

Further, as shown in FIG. 3 and FIG. 11, at the lower center of the rear end main bearing cap portion 16a of the lower block 2, one end is opened to the oil return space 18 and the other end is the rear end main bearing cap portion. An offset passage 33 opening to the lower surface of 16a is formed so as to be displaced inwardly of the lower block 2 with respect to the oil return space 18, and the oil in the oil return space 18 is returned to the oil pan 5.

Further, as shown in FIGS. 9 and 11, the oil return space 18 is provided on the upper surface of the lower block 2 on the side of the rearmost main bearing cap portion 16a.
A communication portion 35 that communicates with the blow-by gas passage 34 therein is provided so as to be displaced inward of the lower block 2 with respect to the oil return space 18. Therefore, the blow-by gas in the crank chamber 4 is generated in the offset passage 33 and the oil return space 18
Also, it is guided to the blow-by gas passage 34 through the communication part 35 and is supplied from the blow-by gas passage 34 to the intake passage.

Therefore, in the above embodiment, the drive gear 10 and the balancer shaft 9 in the oil return space 18 formed between the rear end main bearing cap portion 16a of the lower block 2 and the lower block rear end wall 2b are connected to the drive gear 10 and Since the driven gears 11 meshing with the drive gears 10 and the driven gears 11 are provided, the crankshaft 8 and the balancer shaft 9 do not become long, and it is possible to prevent the entire engine length from increasing.

Further, since the balancer shaft 9 is arranged on the dividing surface between the cylinder block 1 and the lower block 2, the lower block 2
Balancer shaft 9 when assembled to cylinder block 1
Can be easily assembled.

Furthermore, the oil pan rail portion 6 at the lower end of the left side wall 2c is a bulging portion.
Formed in 20, this shape improves its rigidity. Since the front bearing portion 17 of the balancer shaft 9 is connected to the highly rigid bulging portion 20 via the vertical wall 21, the support rigidity of the front bearing portion 17 is improved.

Further, since the rear bearing portion 17 of the balancer shaft 9 is connected to the flange 7 of the lower block 2 via the lateral wall 22, the support rigidity of the rear bearing portion 17 is also improved. Therefore, the balancer shaft 9 can be firmly supported.

Moreover, the mount bosses 23, 23 ...
, And the main bearing cap portions 16, 16 are connected to the mount bosses 23, 23, the rigidity of the mount bosses 23, 23 is extremely high, and the support rigidity of the engine mount is high. improves.

Further, the effect of improving the support rigidity of the balancer shaft 9 and the engine mount is that the side wall of the lower block 2 bulges outward to form a support part for the balancer shaft bearing part 17, and Since the mount boss 23 is merely formed at the intersection with the main bearing cap portion 16, the weight increase of the lower block 2 itself is small.

Further, since the balance holes 24 and 25 are provided in the partition wall 12 on the front side of the cylinder block 1, it is possible to properly alleviate the pressure fluctuations in the crank chamber 4. Moreover, lower block 2
An oil passage 26 for supplying oil to the bearing portion 17 of the balancer shaft 9 to the main bearing cap portions 16 and 16a of the
Since the oil groove 29 is formed, the bearing portion 17 can be satisfactorily lubricated.

In that case, the balance holes 24 and 25 are formed on the mating surface of the cylinder block 1 and the lower member 2 in the front partition wall 12, and the oil groove 29 is aligned with the cylinder block 1 and the lower member 2 in the rear partition wall 14. Since it is formed on the surface, the balancer holes 24, 25 and the oil groove 29 in the cylinder block 1 and the lower member 2 can be easily processed.

Further, since the oil sump portion 32 is formed below the driven gear 11, the end flow oil of the balancer shaft bearing portion 17 accumulated in the oil sump portion 32 is supplied to the driven gear 11 and the drive gear 10, and the respective gears 10, 11 can be lubricated well. In that case, since it is not necessary to form an oil passage or the like in the rear end partition wall 14, the cylinder block 1 has a simple structure.

Moreover, since the lateral wall 31 is formed below the driven gear 11, the lateral wall 31 blocks the scattering of the oil scattered from the driven gear 11 to the crank chamber 4, and reduces the oil mist in the blow-by gas in the crank chamber 4.

Further, the lateral wall 31 increases the rigidity between the lower block rear end wall 2b and the rearmost main bearing cap portion 16a, so that the supporting rigidity of the clutch housing by the cylinder block 1 and the lower block 2 can be improved.

Further, since the offset passage 33 is displaced inward of the lower block 2 with respect to the oil return space 18, the crank chamber 4
The scattered oil or the oil mist in the blow-by gas is obstructed by the wall surface between the offset passage 33 and the oil return space 18 and hardly enters the oil return space 18, and the reverse flow of oil is effectively prevented. Moreover, since the communication portion 35 is displaced inward of the lower block 2 with respect to the oil return space 18, it is possible to reliably prevent the oil mist from entering the blow-by gas passage 34.

Further, since the offset passage 33 is arranged inside the lower block 2 using the rearmost main bearing cap portion 16a, it is not necessary to provide the lower surface of the lower block rear end wall 2b outside, and the length of the oil pan 5 is reduced. It does not become long, and the overall length of the engine can be made compact.

Moreover, the lower block 2 is provided separately from the cylinder block 1, and the oil return space 18,
Since the offset passage 33 and the communication portion 35 are provided, the processing can be simplified.

(Effects of the Invention) As described above, according to the engine balancer shaft drive device of the present invention, the balancer shaft is disposed between the cylinder block and the lower block, and each main bearing cap portion of the lower block is provided. A drive gear for the crankshaft and a driven gear for the balancer shaft in an oil return space formed by the endmost main bearing cap portion located closest to one end wall of the lower block and one end wall of the lower block. Since the crankshaft and the balancer shaft are not lengthened, it is possible to prevent the entire engine length from being lengthened, and it is possible to improve the assemblability of the balancer shaft.

BRIEF DESCRIPTION OF THE DRAWINGS The drawings show an embodiment of the present invention. Fig. 1 is a side view of an engine, Fig. 2 is a front view of the same, Fig. 3 is a bottom view of a lower block, and Fig. 4 is the same plane. 5 and 5 are bottom views of the cylinder block, FIG. 6 is a sectional view taken along line VI-VI in FIG. 3, FIG. 7 is a sectional view taken along line VII-VII in FIG. 4, and FIG.
Fig. 9 is a sectional view taken along line VIII, Fig. 9 is a partially enlarged view of Fig. 4, Fig. 10 is a sectional view taken along line XX in Fig. 9, and Fig. 11 is a vertical sectional side view of the lower block. 1 ... Cylinder block, 1b ... End wall, 2 ... Lower block,
8 ... crankshaft, 9 ... balancer shaft, 10 ... drive gear, 11 ... driven gear, 16 ... main bearing cap part, 16a ... last main bearing cap part, 18 ... oil return space.

Claims (1)

[Claims] 1. A lower block, on which a plurality of main bearing cap portions for integrally rotatably supporting a crankshaft are integrally formed, is disposed below a cylinder block, and the lower block is provided between the cylinder block and the lower block. A balancer shaft rotatably supported by each of the main bearing caps is arranged in parallel with the crankshaft, and a drive gear provided on the crankshaft and a driven gear provided on the balancer shaft are connected to the lower block. One end wall and an outermost main bearing cap portion located closest to the one end wall of the main bearing cap portions of the lower block are engaged with each other in an oil return space. Characteristic engine balancer shaft drive structure.