JP2001289055A - Balancer for engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To minimize noise generated by a balancer. SOLUTION: This balancer device driven through a crankshaft of an engine and a gear is fixed to a cylinder block through an intermediate member manufactured using an iron material with a small coefficient of thermal expansion.

Description

DETAILED DESCRIPTION OF THE INVENTION

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an engine balancer device.

2. Description of the Related Art In a vehicle engine, a rotational balance of a crankshaft is imbalanced due to, for example, a secondary inertial force generated by a reciprocating motion in a vertical direction of a piston. Occurs. For this reason, in Japanese Unexamined Patent Publication No. 4-347032, two balancer shafts provided with eccentric balance weights are rotatably held in a case to form an assembly, and the balance shaft is combined with a crankshaft. The gears are directly meshed. The balance shaft is rotated in opposite directions by the rotational force of the crankshaft to suppress engine vibration. An engine block to which the balancer device is attached may be manufactured using a material having a high coefficient of thermal expansion such as an aluminum-based material for weight reduction. After the engine is started, the block thermally expands as the temperature of the block rises, and the change in the distance between the crankshaft and the balancer shaft increases. As a result, the backlash between the gears of both shafts also increases, and a large noise is generated from the gears due to torque fluctuations applied to the crankshaft.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a balancer device for an engine with low noise.

A first technical solution for solving the above-mentioned technical problem is to support a crankshaft on an engine block made of a material having a relatively high coefficient of thermal expansion. A first gear is arranged on a crankshaft, a balancer shaft provided with a balance weight is housed in a balancer case, and a second gear is arranged on the balancer shaft, and the first and second gears mesh directly or indirectly. Thus, in a balancer device for an engine in which a balancer shaft is driven to rotate by an engine, a balancer case is attached to a cylinder block of the engine via an intermediate member made of a material having a relatively low coefficient of thermal expansion. According to the above means, the crankshaft rotates during the operation of the engine, and the rotation thereof
The balancer shaft, which is housed in the balancer case and has a balance weight, is rotated via the gear and the second gear, so that vertical vibration caused by the secondary inertial force of the engine is suppressed. The intermediate member for attaching the balancer case to the cylinder block is unlikely to thermally expand even when receiving heat during engine operation. A second technical means for solving the above technical problem is that, in addition to the first technical means, the engine block is manufactured from an aluminum-based material, and the intermediate member is manufactured from an iron-based material. According to the above means, even when heat during engine operation is conducted from the engine block to the intermediate member,
The intermediate member is made of an iron-based material and does not easily expand thermally.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of an engine balancer device according to the present invention will be described below with reference to the drawings.
1 to 3, a cylinder block 1 of an engine is shown.
1 is manufactured using a material having a high coefficient of thermal expansion such as an aluminum-based material. A crankshaft 12 is rotatably supported on the cylinder block 11 via a bearing (not shown). A piston (not shown) is engaged with the crankshaft 12 via a connecting rod (not shown). An opening 1 is provided on the lower surface of the cylinder block 11.
A first gear 13 is disposed on the crankshaft 12 at the opening 14. As shown in FIGS. 2 to 5, the case 24 has a hollow portion 25 opened downward, and its support portions 28, 29, 30,
Balancer shafts 22 and 23 are supported in parallel and rotatably via 31. Oil is forcibly supplied to the bearings 28 to 31 via an oil supply passage (not shown). Further, semi-cylindrical balance weights 26 and 27 are formed integrally with the shafts 22 and 23 at the center thereof, and the balance weights 26 and 27 rotate in the hollow portion 25. The balance weights 26 and 27 can be formed separately from the shaft and fastened to the shaft with bolts or the like. Gears 32, 33 meshing with each other are fixed on the balancer shafts 22, 23, and the shafts 22, 23 rotate in directions opposite to each other. The balance weights 26 and 27 are rotated by the balancer shafts 22 and 23 so as to face each other in FIG.
2, 33 engagement positions are determined. A second gear 34 is further provided on the balancer shaft 22 and meshes with the first gear 13 of the crankshaft. These gears 3
Oil is also supplied to 2, 33 and 34 by an appropriate method. As shown in FIG. 5, the lower end surface of the case 24
Are fixed and closed by a plurality of bolts 16.
The case 24 is fixed to a plate-shaped mounting portion 17 of an intermediate member via a bolt 18 via an upper end surface thereof. As shown in FIG. 4, the mounting portion 17 of the intermediate member is provided with gears 32, 33,
An opening 41 is provided at a position corresponding to 34 and the balance weights 26 and 27. However, the balance weights 26 and 2
The upper surface of 7 is covered by a case 24 so that engine oil does not splash on the balance weight. Balancer case 24 attached to attachment portion 17 of the intermediate member
Is fixedly mounted on a cylinder block 11 of the engine via a columnar portion 15 of an intermediate member and a bolt 19. Bolt 1
9 is screwed into the lower end surface of the cylinder block 11 through the columnar portion 15 of the intermediate member. Intermediate member 1
5 and 17 are manufactured using a material having a low coefficient of thermal expansion such as an iron-based material. The case 24 is provided inside an oil pan (not shown) of the engine. As described above, the engine block 11 is manufactured from a material having a relatively high coefficient of thermal expansion such as an aluminum-based material.
5, 17 are manufactured from a material having a relatively low coefficient of thermal expansion such as an iron-based material. In the embodiment configured as described above, when the engine is started, the crankshaft 12 rotates, and the rotation is transmitted to the balancer shaft 22 via the first gear 13 and the second gear 34, and the both balancer shafts 22, 23 are rotated in directions opposite to each other, and vertical vibration caused by the secondary inertial force of the engine is suppressed.

According to the first aspect of the present invention, the balancer case is attached to the cylinder block of the engine via the intermediate member made of a material having a relatively low coefficient of thermal expansion. Even if heat at that time is conducted from the engine block to the intermediate member, the intermediate member is unlikely to thermally expand. Accordingly, the distance between the axes of the first gear on the cylinder block side and the second gear on the balancer case side is minimized, and the amount of change in backlash between the two gears is also minimized. . Therefore, the gear noise caused by the increase in the backlash can be minimized. According to the second aspect of the present invention, even if heat during engine operation is transmitted from the engine block to the intermediate member, the intermediate member is made of an iron-based material and does not easily expand thermally. Accordingly, gear noise due to an increase in the amount of backlash between the first and second gears can be minimized, as in the first aspect.

[Brief description of the drawings]

FIG. 1 is a side view of an engine balancer device according to an embodiment of the present invention.

FIG. 2 is a 2-2 arrow view in which only a balance weight portion in FIG. 1 is seen through;

FIG. 3 is a view taken in the direction of arrows 3-3 in FIG. 2;

FIG. 4 is a view taken in the direction of arrows 4-4 in FIG. 1;

FIG. 5 is a view as seen in the direction of arrow 5 in FIG. 1;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 ... Engine block 12 ... Crankshaft 13 ... 1st gear 26, 27 ... Balance weight 22, 23 ... Balancer shaft 24 ... Balancer case 34 ... 2nd gear 15, 17 ... Intermediate member

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Masaki Kobayashi 2-1-1 Asahicho, Kariya City, Aichi Prefecture Inside Aisin Seiki Co., Ltd.

Claims (2)

[Claims] 1. A crankshaft is supported on an engine block made of a material having a relatively high coefficient of thermal expansion, a first gear is provided on the crankshaft, and a balancer shaft having a balance weight is mounted on a balancer case. And a second gear is disposed on the balancer shaft, and the first and second gears are directly or indirectly meshed with each other to rotate the balancer shaft by the engine. An engine balancer device mounted on a cylinder block via an intermediate member made of a material having a relatively low coefficient of thermal expansion. 2. The engine balancer device according to claim 1, wherein the engine block is manufactured from an aluminum-based material, and the intermediate member is manufactured from an iron-based material.