JPH0447465Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] This invention relates to a compact crankshaft balancer weight that adjusts the rotational balance of the crankshaft.

[Prior art] An example of a balancer weight that adjusts the rotational balance of the engine crankshaft and suppresses vibrations is the "balancer weight for internal combustion engines" (1983-
163557) and ``Crankshaft Balancer Weight'' (Utility Model Application Publication No. 1987-91941).

The proposal for "balancer weight for internal combustion engines" is
As shown in Fig. 3, a weight b, which is of relative importance and is arranged approximately concentrically with respect to the crank center _o1 of the crankshaft a, is attached to the main body, which serves as a base for attaching it to the crankshaft a. It is attached to part c.

In addition, as shown in Fig. 4, the proposal for the "balancer weight for a crankshaft" consists of an outer shell e made of cast iron or the like, with a cavity d whose radial cross section expands in a wedge shape as it approaches the radial direction. A metal f having a relative weight and a low melting point relative to the material constituting the outer shell e is cast into the cavity d.

[Problems to be solved by the invention] However, the former proposal requires a cover or bolt to integrate the weight b and the main body c, which increases the cost, and the latter requires a cover or bolts that are cast into the cavity d. There is a problem in that the metal f, which is relatively important and has a low melting point, shrinks due to heat after being cast, and play is created between the cavity d and the metal g, causing rattling.

[Means for Solving the Problems] In this invention, a cavity is formed in the radially outer part of the balancer fixed to the crankshaft, and the balancers facing each other in the thickness direction through the cavity are formed into a columnar shape. This is a means for solving the problem by connecting them with a member and injecting and solidifying a molten metal having a specific mass into the cavity to form a balancer weight for the crankshaft.

[Operation] When the molten metal mass is poured into the cavity and solidified, the molten metal cools and contracts. This contraction increases the degree of coupling between the metal mass body and the columnar member, and fixes the metal member to the balancer.

[Embodiment] A preferred embodiment of this invention will be described below with reference to the accompanying drawings.

1 shown in Fig. 1 is a crankshaft of an engine, etc., and 2
is the crank pin.

A plurality of balancers 3 are provided on the crankshaft 1 at intervals in the axial direction to adjust the rotational balance of the crankshaft 1 and suppress vibrations.

Now, each balancer 3 in this embodiment is formed as follows.

As shown in FIG. 2, each of the balancers 3 is designed to have a substantially sector-shaped shape with a smaller circumferential portion on the rotation center side of the crankshaft 1 and a larger circumferential portion on the outer side in the radial direction. .

Each balancer 3 in the embodiment is integrally molded by cast iron casting, and at the time of molding, a predetermined thickness is formed in the radially outer portion of the balancer 3 using a core or the like along the circumferential direction and in the thickness direction. A cavity 4 having a thickness t is formed. Further, the cavity 4 is formed to have a predetermined width B in the radial direction. Cavity part 4
The crankshaft 1 is provided with one or more columnar members 6 that form the cavity 4 during casting and connect to each other at portions facing each other in the axial direction of the crankshaft 1. In the embodiment, the columnar members 6 are arranged at two intervals in the circumferential direction.
A book is provided.

The balancer 3 is provided with a sprue 8 that communicates with the cavity 4 on the rotating surface 3a on the radially outer side of the balancer 3. Further, both circumferential ends of the cavity 4 are provided with openings 9, respectively, so as to communicate with the outside.
10.

Now, the cavity 4 formed as described above is filled with molten metal such as lead, which is relatively heavy and has a low melting point, from the sprue 8. The filled metal is then cooled and solidified, and is integrated into the balancer 3 to form the metal mass body 7. Although the metal mass body 7 after cooling will contract here, by providing two or more columnar members 6, it is completely fixed and prevented from rotating. As a result, the metal mass body 7 is free from wobbling.

In this way, since it has become possible to integrally provide the metal mass body 7 with specific gravity and low melting point in the balancer 3, it has become possible to shorten the radial length of the balancer 3 even in a V-type engine. Accordingly, the engine can be made more compact.

It goes without saying that the width B in the radial direction and the thickness t in the thickness direction of the cavity 4 are determined so as to make the rotation radius of the balancer 3 as small as possible.

[Effects of the invention] As is clear from the above explanation, the crankshaft balancer weight of this invention can exhibit the following excellent effects.

(1) Since a metal mass having a specific weight and a low melting point can be integrally provided within the balancer, the rotation radius of the balancer can be reduced.

(2) It is possible to reduce the cost of the balancer.

[Brief explanation of drawings]

Fig. 1 is a front view showing a preferred embodiment of this invention, Fig. 2 is a view taken along the - line in Fig. 1, and Figs. 3 and 4 are schematic diagrams showing a conventional crankshaft balancer. . In the diagram, 1 is the crankshaft, 2 is the crank pin, and 3
4 is a balancer, 4 is a cavity, 6 is a columnar member, and 7 is a metal mass body having a specific weight.

Claims (1)

[Claims for Utility Model Registration] (1) A cavity is formed in the radially outer part of the balancer fixed to the crankshaft, and the balancers facing each other in the thickness direction through the cavity are formed with a columnar member. A balancer weight for a crankshaft, which is connected to the above-mentioned cavity and is made by injecting and solidifying a molten metal having a specific mass into the above-mentioned cavity. (2) The cavity is formed into sections along the rotating direction of the balancer, and the balancer forming the cavity has a sprue through which the molten metal of the metal mass is poured and a part of the poured molten metal flows out to the outside of the balancer. Claim 1 of the above utility model registration having an opening that allows
Crankshaft balancer weight as described in section.