JPS6345561Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a balancer cover mounting structure for an internal combustion engine.

Generally, in an internal combustion engine equipped with a balancer, a balancer cover is provided that surrounds at least the lower end side of the eccentric weight part of the balancer shaft to prevent the balancer shaft from coming into contact with the oil at the bottom of the crank chamber. . Conventionally, special members have been used as means for fixing the balancer cover, which has led to problems such as an increase in the number of parts and a complicated assembly work.

In view of the above problems, the present invention reduces the number of parts and simplifies assembly work by sandwiching and fixing the balancer cover between a boss integrally provided on the side of the crank chamber and the inner surface of the oil pan. The purpose is to measure the
Positioning bosses having the same shape as the opening edges on both sides of the balancer cover are integrally provided below the balancer shaft support on both sides of the crank chamber of the internal combustion engine with a balancer, and the opening edges on both sides of the balancer cover are attached to the bosses. The lower side of the balancer cover is supported by the inner surface of the oil pan that covers the lower end opening of the crank chamber.

EMBODIMENT OF THE INVENTION Hereinafter, a balancer cover mounting structure for an internal combustion engine according to an embodiment of the present invention will be described with reference to the accompanying drawings.

In the figure, numeral 1 is a cylinder block formed by integrally die-casting a cylinder 2 and a crankcase 3, 4 is a cylinder head, 5 is a valve arm cover, 6 is a piston, 7 is a connecting rod, 8 is a crankshaft, 9 1 is a crankcase side cover, 10 is a fan pivotally attached to one end of the crankshaft 8, 11 is a fan case, 12 is a recoil starter, 13 is an intake valve, 1
Reference numeral 4 indicates an exhaust valve, 15 a valve arm, 16 a push rod, and 17 an injection valve.

A crank chamber 18 that opens downward is formed in the crank case 3, and the lower end opening of the crank chamber 18 is sealed by an oil pan 19. Therefore, the inner bottom of the crank chamber 18 is an oil reservoir 39 for engine lubricating oil.

A side cover 9 is fixed to the outside of one side wall 20 of the crankcase 3, and a gear chamber 22 is formed between the two.

A crankshaft 8, a camshaft 23, an oil pump shaft 24, and a balancer shaft 2 are provided between both side walls 20 and 21 of the crankcase 3, passing through them.
5 and 25 are pivotally supported.

The balancer shafts 25, 25 are located below the crankshaft 8, and have eccentric weight portions 26, 26, respectively, which should absorb vertical vibrations caused by the reciprocating motion of the piston 6.

In the gear chamber 22, a crankshaft 7 is provided.
A crank gear 27 is pivotally attached to the camshaft 23 , a cam gear 28 is pivotally attached to the camshaft 23 , a pump gear 29 is pivotally attached to the oil pump shaft 24 , and one balancer shaft 25
A balancer drive gear 30 is housed therein, and these gears 27, 28, 29, and 30 are meshed with an idle gear 31 disposed in the center. Therefore, the rotational force of the crankshaft 8 is transmitted from the crank gear 27 via the idle gear 31 to the camshaft 23, the oil pump shaft 24, and one of the balancer shafts 25 at appropriate rotation ratios.
Note that the balancer shafts 25, 25 are rotated in opposite directions by meshing with balancer gears 32, 32, which are respectively pivotally attached to the balancer shafts 25, 25, thereby canceling and absorbing horizontal rocking.

Further, in the crank chamber 18, the balancer shaft 2
5, 25, their eccentric weight portions 26,
Gutter-shaped balancer covers 33, 33 are provided to surround at least the lower end side of the outer periphery of 26.

In this embodiment, the balancer covers 33, 3
3 is provided as a balancer cover unit 34 which is integrally molded with synthetic resin in parallel.

The balancer cover unit 34 has the function of preventing the eccentric weight portion 26 of each balancer shaft 25 from coming into contact with the oil stored in the inner bottom of the crank chamber 18.

On the other hand, both side walls 20 and 21 of the crank chamber 18
, both open edges 33a, 33b of each balancer cover 33 are provided below the shaft support of each balancer shaft 25.
Positioning bosses 35 and 36 having the same shape as the opening edges of the balancer cover unit 34 are each formed integrally during die-casting. That is, the opening edges on both sides of the balancer cover unit 34 can be brought into close contact with the boss portions 35 and 36 from below.

A plurality of leg-shaped boss portions 37, 37, . . . are integrally provided on the lower surface of the balancer cover unit 34 in a protruding manner.

Further, on the inner surface of the oil pan 19, there are support boss portions 38 for supporting the leg-shaped boss portions 37, 37, .
38... are integrally formed.

After the opening edges on both sides of the balancer cover unit 34 are brought into contact with the positioning bosses 35, 36 of the crank chamber side walls 20, 21, the leg-like bosses 37, 3 of the balancer cover unit 34 are removed.
7... are the support boss parts 38, 38 of the oil pan 19.
The balancer cover unit 34 is fixed within the crank chamber 18 by being supported by...

By doing this, the balancer cover unit 3
4 is a boss portion 35, 3 that can be integrally molded when manufacturing the crankcase 3 and oil pan 19.
6 and the support boss portions 38, 38, . . . , it can be clamped and fixed, and no special members for attachment are required at all.

Next, the effects of the balancer cover mounting structure for an internal combustion engine according to the present invention will be described.

According to the present invention, the positioning boss portion 3 is formed by integrally protruding both side opening edges 33a and 33b of the balancer cover 33 on both side walls 20 and 21 of the crank chamber 18.
5, 36 and the inner surface of the oil pan 19 that covers the lower end opening of the crank chamber 18, so a separate member for mounting the balancer cover is not required, reducing the number of parts and simplifying the assembly work. It has the practical effect of being able to measure the

In addition, the boss portions 35 and 36 are attached to the balancer cover 3.
Since both opening edges 33a and 33b of No. 3 have the same shape, both opening edges 33 have the same shape as the boss portions 35 and 36.
a and 33b are brought into close contact, which also has the advantage of preventing oil from entering into the balancer cover 33.

[Brief explanation of drawings]

FIG. 1 is a longitudinal sectional front view of an internal combustion engine having a balancer mounting structure according to an embodiment of the present invention, FIG. 2 is a cross-sectional view taken from FIG. It is a diagram. 3...Crank case, 8...Crankshaft, 1
8...Crank chamber, 19...Oil pan, 20,
21... Crank chamber side wall, 25... Balancer shaft,
26... Eccentric weight part, 33... Balancer cover,
33a, 33b...Opening edge, 35, 36...Boss portion.

Claims (1)

[Scope of utility model registration request] A balancer shaft 25 that interlocks with the crankshaft 8 is installed below the crankshaft 8 in the crank chamber 18 in the crankcase 3, and below the balancer shaft 25, an eccentric weight portion 26 surrounding at least the lower end side of the outer periphery thereof is installed. In an internal combustion engine provided with a trough-like balancer cover 33, both side walls 20, 21 of the crank chamber 18 have side opening edges 33a, 33 of the balancer cover 33 below the balancer shaft support.
Positioning boss portions 35, 36 having the same shape as b are integrally protruded, and both opening edges 33a, 33b of the balancer cover 33 abut against the boss portions 35, 36, and the lower side surface of the balancer cover 33 A balancer cover mounting structure for an internal combustion engine, characterized in that the balancer cover is supported on the inner surface of an oil pan 19 that covers a lower end opening of the crank chamber 18.