JPH0633989A - Engine equipped with balancer shaft - Google Patents

Abstract

PURPOSE:To compact an engine equipped with a balancer shaft. CONSTITUTION:A balancer shaft 3 has a main eccentric shaft 6, 7 formed thereon with an axial offset to the center of an engine and a sub-eccentric weight 8 formed thereon with an eccentricity from its axis of rotation to the radially opposite side to the main eccentric weight 6, 7 and with an offset to the far side of the center of the engine.

Description

Detailed Description of the Invention

[0001]

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

[0002]

2. Description of the Related Art Some automotive engines and the like rotate a balancer shaft having an eccentric weight in synchronization with the engine rotation (Japanese Patent Laid-Open No. 63-167145).
Gazette, reference).

A conventional engine with a balancer shaft is
As shown in FIG. 5, the eccentric weight 32 of the balancer shaft 31 is arranged at the engine center, and the eccentric weight 3
The inertial force Fb applied by 2 cancels out the inertial force Fe and the like of the piston and the connecting rod, and suppresses fundamental order vibration having a frequency twice that of the engine rotation.

The eccentric weight 32 is arranged in the engine center and the distance between the point of action of each inertial force Fe, Fb and the center of gravity of the power plant is made equal to cancel the pitching moment with respect to the power plant.

[0005]

However, in such a conventional engine with a balancer shaft,
Since the eccentric weight 32 must be arranged in the engine center, not only the balancer shaft 31 becomes longer, but also the size of the engine becomes larger, for example, when the balancer shaft 31 is housed in the oil pan, the oil pan becomes larger. invited.

In view of the above points, the present invention aims to make an engine with a balancer shaft compact.

[0007]

SUMMARY OF THE INVENTION The present invention provides a balancer shaft engine in which a balancer shaft having an eccentric weight is arranged in parallel with a crankshaft, and a balancer shaft is provided with a power transmission mechanism for transmitting rotation of the crankshaft. The main eccentric weight is formed on the shaft by offsetting it in the axial direction of the balancer shaft with respect to the engine center, and the sub-eccentric weight is eccentric to the main eccentric weight with respect to the rotation axis of the balancer shaft, and from the engine center. Offset to the far side to form.

[0008]

[Operation] The basic force vibration of the engine is suppressed by canceling the inertial force exerted by the piston, connecting rod, etc. by the combined force of the inertial force exerted by the main eccentric weight and the inertial force exerted by the sub-eccentric weight as the balancer shaft rotates. To do.

By forming the sub-eccentric weight on the opposite side in the radial direction with respect to the rotating shaft of the balancer shaft and by offsetting it to the side far from the engine center, the main eccentric weight for the power plant including the engine and the transmission is formed. The subtraction between the pitching moment given by the sub-eccentric weight and the pitching moment generated by the engine reciprocating motion system such as the piston and the connecting rod is offset by the pitching moment given by the sub-eccentric weight.

By thus disposing the eccentric weight of the balancer shaft while avoiding the engine center, the length of the balancer shaft can be shortened and the engine can be made compact.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS As shown in FIGS. 1 and 2, a crankshaft 2 is supported under a lower portion of an engine block 1 provided in an in-line 4-cylinder engine via five bearing caps 11, and a crankshaft 2 is provided below the crankshaft 2. A book balancer shaft 3 is supported via a balancer housing 12.

An upper oil pan 21 and a lower oil pan 22 are attached to the lower portion of the engine block 1. Lubricating oil stored in the lower oil pan 22 is sucked up by an oil pump through an oil strainer (not shown) to lubricate each part of the engine, and then the upper oil pan 2
Return to the lower oil pan 22 via 1.

The balancer housing 12 is arranged between the lower oil pan 22 and the crankshaft 2. This engine is installed horizontally in the engine room of the vehicle. It is located behind the lower oil pan 22 (to the left in the case of the vehicle) and below the upper oil pan 21, and the exhaust pipe 23 and the center member of the vehicle body. 24 are arranged.

Each balancer shaft 3 is formed with two journal portions 4 and 5, and the balancer housing 12 is formed with two pairs of bearings 18 and 19 which support the respective journal portions 4 and 5.

Each balancer shaft 3 is arranged in parallel with the crankshaft 2, and the rotational force of the crankshaft 2 is
A reversing gear 16, which is transmitted to one balancer shaft 3 through a sprocket 13, a chain 14, and a sprocket 15 and is coupled to both balancer shafts 3 and meshes with each other,
It is transmitted to the other balancer shaft 3 via 17.
Thus, a power transmission mechanism that rotationally drives the balancer shafts 3 in opposite directions at a speed twice that of the crankshaft 2 is configured.

In FIG. 1, # 1 bulk center is # 1.
Located in front of the cylinder, the # 2 bulk center is located between the # 1 cylinder and the # 2 cylinder. In the case of this 4-cylinder engine, the engine center is on the # 3 bulk center located between the # 2 cylinder and the # 3 cylinder. The engine center is located in the center of the crankshaft 2 and
It is located at the center of the four pistons and connecting rods and serves as the point of action of the inertial force applied by the reciprocating system of the engine.

Each balancer shaft 3 is offset forward from the engine center in the axial direction. In the balancer housing 12, each bearing 18 is arranged on the # 1 bulk center, and each bearing 19 is arranged on the # 2 bulk center.

Each balancer shaft 3 is formed with a pair of main eccentric weights 6 and 7 sandwiching a rear journal portion 5. The main eccentric weights 6 and 7 are eccentrically formed in the same direction with respect to the rotation axis of each balancer shaft 3, and cancel out inertial forces of pistons, connecting rods and the like.

In each balancer shaft 3, a sub eccentric weight 8 is formed between the front journal portion 4 and the front main eccentric weight 6. Each sub eccentric weight 8 is eccentric to the rotation axis of each balancer shaft 3 in the direction opposite to each main eccentric weight 6, 7.

As a result, each main eccentric weight 6, 7
Is formed to be offset from the engine center in the axial direction thereof, and each sub-eccentric weight 8 is formed to be offset from the engine center to the main eccentric weights 6 and 7 in the axial direction.

In FIG. 4, Fe is an inertial force acting on an engine reciprocating motion system such as a piston and a connecting rod, and its operating point is at the engine center. If Fm is the resultant force of the inertial forces acting on each main eccentric weight 6 and 7, and Fs is the resultant force of the inertial forces acting on each sub-eccentric weight 8, Fe + Fs = Fm (1) In addition, the transmission connected to the engine body and its rear part is The distance of the engine center with respect to the center of gravity of the power plant is Le, the distance of the point of action of the inertia force Fm acting on each of the main eccentric weights 6 and 7 is Lm, and the distance of the inertia force Fs acting on each of the sub-eccentric weights 8 is Ls. Then, Fe · Le + Fs · Ls = Fm · Lm (2) Set the masses and dimensions of the main eccentric weights 6 and 7 and the sub eccentric weights 8 so as to satisfy the above expressions (1) and (2). As a result, the inertial force acting on the engine reciprocating system is canceled out, and the secondary vibration of the engine is suppressed. Further, the pitching moment given by each sub-eccentric weight 8 is the difference between the pitching moment given by each main eccentric weight 6 and 7 to the center of gravity of the power plant and the pitching moment generated by the engine reciprocating motion system such as the piston and connecting rod. Is offset by.

By thus offsetting each balancer shaft 3 forward of the engine center, the front-rear length of the lower oil pan 22 accommodating the balancer housing 12 is shortened, and these are arranged in the vicinity thereof. It is possible to avoid the interference with the exhaust pipe 23 or the center member 24 of the vehicle body.

[0023]

As described above, according to the present invention, the main eccentric weight is formed on the balancer shaft by offsetting it in the axial direction of the balancer shaft with respect to the engine center, and the sub-eccentric weight is provided with the main eccentric weight about the rotating shaft of the balancer shaft. Since it was formed to be eccentric to the opposite side in the radial direction and offset to the side far from the engine center, the length of the balancer shaft is shortened and the engine can be made compact, so that it can be mounted on a vehicle. Layout can be facilitated.

[Brief description of drawings]

FIG. 1 is a longitudinal sectional view of an engine showing an embodiment of the present invention.

FIG. 2 is a perspective view of the engine of the same.

FIG. 3 is a perspective view of the balancer shaft.

FIG. 4 is a layout view of the balancer shaft.

FIG. 5 is a layout view of a balancer shaft showing a conventional example.

[Explanation of symbols]

 1 Engine Block 2 Crank Shaft 3 Balancer Shaft 6 Main Eccentric Weight 7 Main Eccentric Weight 8 Sub Eccentric Weight 21 Upper Oil Pan 22 Lower Oil Pan

Claims (1)

[Claims] 1. A balancer shaft engine having a balancer shaft having an eccentric weight arranged in parallel with a crankshaft and having a power transmission mechanism for transmitting rotation of the crankshaft to the balancer shaft, wherein a main eccentric weight is provided on the balancer shaft. Is formed by offsetting in the axial direction of the balancer shaft, the sub-eccentric weight is eccentric to the main eccentric weight with respect to the rotating shaft of the balancer shaft in the radial opposite side, and is offset to the side far from the engine center. An engine with a balancer shaft.