JPH05288241A - Internal combustion engine equipped with balancer shaft - Google Patents

Abstract

PURPOSE:To enhance the rigidity for supporting a crankshaft and a balancer shaft in an internal combustion engine equipped with the balancer shaft without deteriorating productivity. CONSTITUTION:A balancer shaft 2 is disposed on the side of a course C of rotation at the large end portion of a connecting rod and on an oil pan 5 and a crank carrier 4 for supporting a crankshaft 1 is provided between an engine block 3 and the oil pan 5. A cross beam portion 10 for connecting the right and skirt portions 13 of the bearing portion 11 of the crankshaft 1 to the crank carrier 4 is integrally formed and the bearing portion 12 of the balancer shaft 2 is open to the cross beam portion 10.

Description

Detailed Description of the Invention

[0001]

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

[0002]

2. Description of the Related Art Conventionally, there is a device for canceling an inertial force of a piston or the like by rotating a balance shaft having an unbalanced mass in synchronization with engine rotation.

As an apparatus of this type, for example, Japanese Patent Laid-Open No. 63-
The one disclosed in Japanese Patent No. 186050 includes an engine block having a cylinder wall and a box-shaped lower block connected to a lower end of the engine block, and a crankshaft bearing portion and a balance are provided between the engine block and the lower block. A shaft bearing portion is provided. By forming the lower block in a box shape, the rigidity of supporting the crankshaft and the balance shaft is increased.

[0004]

However, in such a conventional apparatus, since the crankshaft bearing portion and the balance shaft bearing portion are opened between the engine block and the lower block, the engine of the engine is not opened. When machining the crankshaft bearing part and the balance shaft bearing part respectively during manufacturing, it is necessary to temporarily join the engine block and the lower block to each other, and a new large-scale production facility corresponding to this is required. There was a problem that

Further, since the housing portion for accommodating the balance shaft is formed to bulge out to the side of the engine block, the size of the engine is increased.

[0006] As a countermeasure against this, there is an attempt to miniaturize the engine by disposing a balance shaft inside the oil pan. In this case, the balance shaft rotating at a high speed strikes or stirs the lubricating oil to prevent friction. There was a problem of causing an increase.

The present invention focuses on the above problems and aims to solve them.

[0008]

DISCLOSURE OF THE INVENTION The present invention is directed to an internal combustion engine with a balance shaft which is arranged parallel to the crankshaft and which rotates in synchronization with the crankshaft. A crank carrier that supports the crankshaft is provided between the engine block and the oil pan on the side of the path and on the oil pan, and the horizontal beam part that connects the left and right skirt parts of this crank carrier and the crankshaft are cranked. It is provided on the carrier, and the bearing portion of the balance shaft is opened in this cross beam portion.

[0009]

By arranging the balance shaft on the side of the rotation path at the large end of the connecting rod, it is possible to prevent the engine from increasing in size due to the space provided for the balance shaft. Further, by disposing the balance shaft on the oil pan, it is possible to prevent the lubricating oil stored in the oil pan from being hit or agitated, and suppress an increase in friction.

Although the crankshaft is bent and deformed by the combustion pressure applied to the piston, etc., a horizontal beam portion connecting the bearing portion of the crankshaft and the skirt portion is integrally formed on the crank carrier, and the bearing portion of the balance shaft is opened in this horizontal beam portion. With this structure, the rigidity of supporting the crankshaft and the balance shaft is increased, and engine vibration can be suppressed.

The bearing portion of the balance shaft, which opens to the lateral beam portion of the crank carrier, can be machined in a subline independent of the engine block, and the engine block and the lower block shown in the prior art are temporarily joined to each other. You can reduce the number of man-hours required for machining in this state and raise the production system.

[0012]

Embodiments of the present invention will be described below with reference to the accompanying drawings.

As shown in FIG. 1, two balance shafts 2 are arranged in parallel with each other below and to the left and right of a crankshaft 1 provided in an in-line four-cylinder engine. In this case, each balance shaft 2 has a length that is approximately half the total length of the engine, and is arranged in front of the center of the engine in the cylinder column direction.

Each balance shaft 2 is located on the side of the rotation path C at the large end of the connecting rod shown by the chain double-dashed line in FIG.
Further, it is arranged on the oil surface of the lubricating oil stored in the oil pan 5.

The head-integrated engine block 3 includes a cylinder wall 32 forming a cylinder bore 31, a combustion chamber wall 37 defining a combustion chamber, an intake port 33, an exhaust port 34,
A bearing portion 35 that supports the crankshaft 1 and a skirt portion 36 that defines the crank chamber 9 are integrally formed.

A crank carrier 4 is interposed between the engine block 3 and the oil pan 5, and an oil pan 5 is connected to the lower end of the crank carrier 4.

As shown in FIG. 2, the crank carrier 4
Has a box-shaped skirt portion 13 that defines the crank chamber 9, and integrally forms a lateral beam portion 10 that connects the left and right skirt portions 13 and the bearing portion 11 of the crankshaft 1 in a beam shape. The bearing portion 12 of each balance shaft 2 is opened.

The lower ends of the respective bearings 11 of the crankshaft 1 are connected by vertical beam portions 17 extending vertically in the shape of beams to enhance the support rigidity for the crankshaft 1.

The crank carrier 4 has two bolt holes 16 formed on the left and right of each crankshaft bearing 11.
It is fastened to the engine block 3 by bolts 6 which pass through the bolt holes 16 and are screwed into the engine block 3.

The crank carrier 4 has a joining flange 14 for the skirt portion 36 of the engine block 3 formed at the upper end of the skirt portion 13 and a joining flange 15 for the oil pan 5 at the lower end thereof.

As shown in FIG. 3, a timing belt 21 is provided at the front of the engine to drive each balance shaft 2 by the crankshaft 1. A drive pulley 22 is connected to the crankshaft 1, and each balance shaft 2
The driven pulleys 23 and 24 are connected to the driven pulley 24, and the tensioner pulley 2 is diagonally above the driven pulley 24 on the left side.
5 are provided. The timing belt 21 has teeth on both inner and outer circumferences that mesh with each pulley. The right driven pulley 23 meshes with its inner circumference teeth, and the left driven pulley 24 meshes with its outer circumference teeth. Right and left driven pulley 2
3, 24 rotate in mutually opposite directions. As described above, the structure in which the one balance shaft 2 is driven by the outer circumference (back surface) of the timing belt 21 eliminates the reverse gear provided in the conventional device, and simplifies the structure.

The pulley ratio of each balance shaft 2 is set so as to rotate at twice the speed of the crankshaft 1,
The centrifugal force acting on each unbalanced mass cancels out the inertial force of Pinston, connecting rod, etc. to suppress engine vibration.

The crankshaft 1 rotates in the direction indicated by the arrow A in the drawing, the tensioner pulley 25 meshes with the inner peripheral teeth on the loose side of the timing belt 21, and the timing belt 21 is urged by a spring (not shown). Give proper tension to.

As shown in FIG. 2, the front wall 28 of the crank carrier 4 has a mounting seat 1 for the tensioner pulley 25.
8 is formed so as to project to the left side, and a hole 19 for fitting the support shaft of the tensioner pulley 25 into the mounting seat 18 and a hole 20 for fitting one end of a spring for pressing the tensioner pulley 25 against the timing belt 21 and urging the same. And are formed.

As described above, by forming the engine block 3 integrated with the head portion and the crank carrier 4 separately, the shape of the engine block 3 is simplified and molding by casting is facilitated.

Each balance shaft bearing portion 12 opening to the lateral beam portion 10 of the crank carrier 4 can be machined in a sub line independent of the engine block 3, and as a result, the crank carrier 4 is attached to each engine block 3. In the main line that cuts the crankshaft bearings 11 and 35 with the bolts 6 fastened,
Since it is not necessary to form each bearing portion 12 of each balance shaft by machining, it is not necessary to change the production equipment in the main line.

Although the crankshaft 1 is bent and deformed by the combustion pressure received by the piston, the crank carrier 4 has a bearing portion 11 and a skirt portion 13 of the crankshaft 1.
With the structure in which the lateral beam portion 10 that connects the two is integrally formed, the support rigidity of each bearing portion 11 against the bending deformation of the crankshaft 1 is increased, and engine vibration can be suppressed.

Further, since the mounting seat 18 for the tensioner pulley 25 is integrally formed on the front wall 28 of the crank carrier 4, the supporting rigidity for the tensioner pulley 25 is sufficiently secured, and the number of parts is reduced to improve the productivity. To be enhanced.

By arranging each balance shaft 2 on the surface of the lubricating oil stored in the oil pan 5, the lubricating oil is hit by the balance shaft 41 rotating at a high speed,
Prevents friction from increasing without stirring.

By arranging the balance shafts 2 on the left and right sides so as to sandwich the rotation path C of the large end portion of the connecting rod, it is possible to prevent the engine from increasing in size due to the space in which the balance shafts 2 are interposed.

[0031]

INDUSTRIAL APPLICABILITY As described above, the present invention is an internal combustion engine with a balance shaft which is arranged parallel to the crankshaft and which rotates in synchronization with the crankshaft. Place it on the side of the rotation path and on the oil pan,
A crank carrier that supports the crankshaft is provided between the engine block and the oil pan, and a horizontal beam portion and a crankshaft that connect the left and right skirt portions of the crank carrier are provided in the crank carrier. The opening of the engine reduces the size of the engine, increases the support rigidity against bending deformation of the crankshaft and suppresses engine vibration, and the bearing part of the balance shaft is machined in a subline independent of the engine block. This makes it possible to increase the production system by eliminating the need for large-scale production equipment.

[Brief description of drawings]

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

FIG. 2 is a perspective view of a crank carrier of the same.

FIG. 3 is a front view showing each pulley, timing belt and the like.

[Explanation of symbols]

 1 Crank Shaft 2 Balance Shaft 3 Engine Block 4 Crank Carrier 5 Oil Pan 9 Crank Chamber 10 Cross Beam Part 11 Crank Shaft Bearing Part 12 Balance Shaft Bearing Part 13 Skirt Part 18 Tensioner Pulley Mounting Seat 21 Timing Belt 22 Drive Pulley 23 Driven Pulley 24 Driven pulley 25 Tensioner pulley 32 Cylinder wall

Claims (1)

[Claims] 1. An internal combustion engine with a balance shaft, which is arranged parallel to the crankshaft and has a balance shaft that rotates in synchronization with the crankshaft, wherein the balance shaft is located laterally of the rotation path at the large end of the connecting rod and in the oil pan. A crank carrier that supports the crankshaft is installed between the engine block and the oil pan, and a horizontal beam and a crankshaft that connect the left and right skirts of this crank carrier are provided on the crank carrier. An internal combustion engine with a balance shaft, characterized in that the bearing portion of the balance shaft is opened.