JPH0218843Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to the structure of a balancer shaft of an engine, and particularly to an improved structure of an axial positioning means for the balancer shaft.

[Conventional technology]

In piston-crank engines,
In order to balance the unbalanced primary inertial forces of the reciprocating portion and the crankshaft, a balancer shaft is provided which is driven in constant reverse rotation by the crankshaft. This balancer shaft is provided with a balancer weight portion having a predetermined weight and eccentric to the balancer shaft.

Since this type of balancer shaft is supported adjacent to and parallel to the crankshaft, its axial position must be regulated to prevent contact with the crankshaft or noise generation.

Therefore, conventionally, as means for axially positioning the balancer shaft, a collar is provided on the balancer shaft and a stopper is provided on the crankcase side, and these are brought into sliding contact with each other to regulate the axial position of the balancer shaft. is used.

[Problem that the invention attempts to solve]

However, in the conventional axial positioning means of this type, the flange is formed at a different position from the balancer weight, so it is necessary to avoid interference between the balancer weight and the crank web of the crankshaft. , it is necessary to arrange the separate flange to avoid interference with the crank web, etc., and for this reason, the distance between the crankshaft and balancer shaft becomes large, or the length of the crankshaft and balancer shaft increases. There was a problem that the size of the engine became larger, the external dimensions of the engine became larger, and the weight also increased.

〔the purpose〕

The purpose of the present invention is to provide an engine balancer that can solve the problems of the conventional structure and reduce the axial space of the balancer shaft or the distance between the balancer shaft and the crankshaft, thereby making the engine smaller and lighter. It is to provide an axis.

[Means to solve the problem]

The present invention achieves the above object by forming a positioning collar part integrally with the side surface of the balancer weight part provided on the balancer shaft.

[Example] The present invention will be specifically described below with reference to the drawings.

FIG. 1 shows the main parts of an engine equipped with a balancer shaft according to an embodiment. A crankshaft 2 and a balancer shaft 3 are supported in a crankcase 1 in parallel with each other with a predetermined distance between the shafts. , the balancer shaft 3 via a gear 4 provided on the crankshaft 2 and a balancer gear 5 provided on the balancer shaft 3.
It is configured to drive in constant speed reverse rotation.

The illustrated engine has two cylinders, and the crankshaft 2 is provided with a pair of crank webs 6, 7 and a crank pin 8 between the two crank webs 6, 7 for each cylinder. Moreover, on the opposite side of each crank web 6, 7, weights 9, 10 are integrally formed to balance the mass of the large end rotating part and correspond to 1/2 of the mass of the reciprocating part.

The balancer gear 5 is attached to the balancer shaft 3 via a damper mechanism capable of absorbing fluctuating torque.

That is, on the outer periphery of the holder 11 fixed to the balancer shaft 3, via the damper spring 12,
A balancer gear 5 is fitted in a rotatable manner. Furthermore, holding plates 13 and 14 are provided on both sides of the holder 11 to prevent the balancer gear 5 and damper spring 12 from falling off.

FIG. 2 shows a partial cross section taken along the line--in FIG.

As shown in FIGS. 1 and 2, balancer weight portions 15 and 16 are formed on the balancer shaft 3 at two locations separated in the axial direction. Both balancer weight parts 15 and 16 are formed at positions 180 degrees apart from each other, that is, on opposite sides in the circumferential direction.

In addition, the illustrated engine is a two-cylinder engine,
Each balancer weight part 15, 16 is formed at a position corresponding to the crank pin 8 of each cylinder. That is, the balancer weight part 15 is located between a pair of weights 9 and 10 in the left cylinder, and the balancer weight part 16 is located in a similar relationship between a pair of weights (not shown) in the right cylinder. There is.

As shown in FIGS. 1 and 2, an annular collar portion 18 is integrally formed on the right (inside) side surface of the balancer weight portion 15. As shown in FIGS. Further, a similar annular collar portion 19 is integrally formed on the left (inside) side surface of the other balancer weight portion 16.

As shown in FIGS. 1 and 2, the crankcase 1 (side) is provided with stoppers 20 and 21 that abut against the flange portions 18 and 19. As shown in FIGS. As shown in FIG. 2, each stopper 20, 21 has a shape that abuts against the collar portions 18, 19 within a partial arc.

In this way, the balancer shaft 3 has each flange 18, 1
The axial position is determined by the contact between the stopper 9 and each stopper 20, 21.

According to the structure of the embodiment described above, since the flanges 18 and 19 are provided integrally with the side surfaces of the balancer weight parts 15 and 16, as is clear from FIG. Regarding this, the contact surface (flange portion 18) of the stopper 20 can be formed without substantially increasing the width of the balancer weight portion 15, and therefore the distance between the weight portions 9 and 10 of the crankshaft 2 can also be reduced. The balancer shaft positioning means can be constructed with almost no increase in size, and the engine width can be made smaller compared to the conventional one having an independent flange, making it possible to reduce the size and weight of the engine.

This is exactly the same for the collar portion 19 that utilizes the side surface of the other balancer weight portion 16.

Furthermore, the brim portion 18 is the balance weight portion 15
Since it is integrated with the main body and the overall width can be made almost the same,
Compared to the case where similar flange portions are provided at other positions, the overlapping margin (side surface lap amount) between the balancer weight portion 15 and the pair of weight portions 9 and 10 of the crankshaft 2 is made sufficiently large (as shown in FIG. 1). deeply)
Since it can be set, the crankshaft 2
It is also possible to reduce the distance between the balancer shafts 3 and the balancer shaft 3, which also allows the engine to be made smaller and lighter.

This is exactly the same for the other balancer weight section 16.

In the illustrated embodiment, the flanges 18 and 19 are formed using one side surface of each balancer weight portion 15 and 16, but this is different from forming the flanges 18 and 19 by using both side surfaces of one balancer weight portion. 18,1
9 can also be formed.

Further, in the illustrated example, the outside of each stopper 20, 21 is brought into contact with the inner surface of each collar 18, 19;
The same effect can be obtained by forming a collar portion on the opposite side surface of the ribs 5 and 16 so as to abut the ribs in opposite directions.

[Effect of idea]

As is clear from the above description, according to the present invention, it is possible to reduce the axial space and the distance between the shafts of an engine having a balancer shaft that is rotationally driven by a crankshaft, thereby making it possible to reduce the size and weight of the engine. The engine balancer shaft is obtained.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal sectional view of a main part of an engine equipped with a balancer shaft according to an embodiment of the present invention, and FIG. 2 is a partial sectional view taken along the line - in FIG. 1. 1...Crank case, 2...Crankshaft, 3...Balancer shaft, 15, 16...Balance weight part, 18, 19...Brim part, 20, 21
...Stotsupa.

Claims (1)

[Scope of utility model registration request] In a balancer shaft of an engine having a balancer weight part and driven in constant reverse rotation by a crankshaft, a flange part is formed integrally with the side surface of the balancer weight part, and a stopper provided on the crankcase side is attached to the flange part. An engine balancer shaft characterized by being brought into contact with the engine for axial positioning.