JPH036382B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a vibration prevention device for an in-line 4-cylinder engine in which a crankshaft with a flywheel connected to one end is supported by bearings at five locations. .

(Prior art) In general, in an in-line four-cylinder engine (see "Capella, Structure and Maintenance" published by Toyo Kogyo Co., Ltd., October 1978 edition), torque is intermittently loaded on the crankshaft depending on the combustion pressure of each cylinder. As a result, the crankshaft undergoes torsional displacement and its journal portion periodically collides with the bearing, which acts as an excitation force on the engine, causing engine vibrations caused by the torsional displacement of the crankshaft. was occurring.

(Object of the Invention) The present invention provides a shock absorbing means for a specific bearing that supports the crankshaft, thereby effectively reducing the vibration part of the engine vibration caused by the torsional vibration of the crankshaft. The purpose of this invention is to provide a vibration prevention device for an in-line four-cylinder engine.

(Structure of the Invention) The present invention provides a crankshaft having four pin parts and five journal parts, each of which is connected to a flywheel at one end of the crankshaft. In an in-line four-cylinder engine supported by first, second, third, fourth, and fifth bearings, the crankshaft generates maximum torque in the second and fourth bearings and also in the crankshaft. At a suitable location in the direction orthogonal to the arm, an appropriate one acts to alleviate and absorb the excitation force generated due to the torsional vibration of the crankshaft transmitted from the crankshaft side to the second and fourth bearing portion sides. The present invention is characterized in that a shock absorbing means is provided to prevent as much as possible the part of engine vibration caused by torsional vibration of the crankshaft.

(Theoretical Background of the Invention) The present invention provides an in-line four-cylinder engine with a second bearing of five bearings that support the crankshaft of the engine.
By providing a shock absorbing means in the fourth bearing part, engine vibrations caused by torsional vibrations of the crankshaft are more effectively prevented. First, the theoretical background of the present invention is explained in Figs. 1 and 2.
This will be explained based on the diagram. .

Now, as shown in Fig. 1, there are four pin parts, namely the first
Pin part 2A, second pin part 2B, third pin part 2C,
The fourth pin part 2D and the five journal parts, that is, the first
Journal part 3A, second journal part 3B, third
Journal part 3C, fourth journal part 3D, fifth
It has a journal part 3E and a fifth journal part 3.
In-line 4 with flywheel 6 attached to the outer end of E
Each of the journal portions 3A of the cylinder crankshaft 1,
3B, 3C, 3D, and 3E, respectively, in the first bearing part 7
A, the second bearing part 7B, the third bearing part 7C, the fourth bearing part 7D and the fifth bearing part 7E respectively support the bearings, and the pin parts 2A, 2B, 2C,
2D, the connecting rod 5A of the first piston 4A, and the second
It is assumed that the connecting rod 5B of the piston 4B, the connecting rod 5C of the third piston 4C, and the connecting rod 5D of the fourth piston 4D are connected.

When the engine is operated, torsional torque is applied to the crankshaft 1, but since the diameter of the pin part of the crankshaft is generally smaller than the diameter of the journal part, the torsion angle is smaller than that of the journal part. becomes larger than the journal part. For example, if the diameter of the journal part is 50 mm and the diameter of the pin part is 40 mm, the torsion angle is inversely proportional to the fourth power of the diameter, so the ratio of the torsion angle of the journal part to the pin part is 1:2.44.

Here, it is assumed that the torsion angle of the journal part is small and can be ignored, and that each crank arm part is also highly rigid and will not bend or torsionally displace.
2D and each journal section 3A, 3B, 3C, 3D,
The torsion form of the primary torsional vibration of 3E is schematically illustrated in FIG. Now, the axial center position of the fifth journal portion 3E to which the flywheel 6 is connected is represented as position a (origin) in FIG.
For example, the axial center positions of the other journal parts and pin parts relative to the first piston 4A and the fourth piston 4
Considering the case where D is at the top dead center position and the fifth piston 4B and the third piston 4C are at the bottom dead center position, the fourth pin part 2D is vertically moved through position a because the fifth journal part 3E is not torsionally displaced. The fourth journal part 3D is located at position b on the first straight line _l1 extending to
Because the fourth pin portion 2D is torsionally displaced, the second straight line l is inclined from the first straight line _l1 by an angle α (exaggerated than the actual torsion angle) by the torsional displacement of the fourth pin portion 2D. Since _{the third} journal part 3D is not torsionally displaced, the third pin part 2C is at position c on the second straight line l ₂ and at position b relative to position c.
At position d, which is symmetrical to
C is at position d because the third pin part 2C is torsionally displaced.
It is located at position a on a third straight line _l3 that passes through and is inclined by an angle α with respect to the second straight line _l2 . That is, the third
The journal portion 3C remains at the initial position and is hardly displaced. Therefore, these parts are at position a, position b,
Draw a first closed curve _P1 in the form of an isosceles triangle connecting position c and position d. On the other hand, the first pin portion 2A, the second pin portion 2B, the first journal portion 3A, and the second journal portion 3B are connected to the fourth pin portion 2D, the third pin portion 2C, the fifth journal portion 3E, and the fourth journal portion, respectively. Since these points are located at a line symmetrical position with respect to the third journal part 3C with respect to the third journal part 3D, each of these points forms a second closed curve _P2 which is line symmetrical to the first closed curve _P1 with respect to the third straight line _l3. They are located at positions a, d, e, and f above, respectively. From this FIG.
It can be seen that only point D is largely displaced in the left-right direction from position a, that is, the journal neutral point, and therefore, the impact force (excitation force) that excites the engine acts on the bearing portion corresponding to this portion.

Also, the actual torsion angle α of each pin portion is minute, so if this angle α is brought closer to 0, positions c and e will be in the third straight line _l3 , that is, in the direction perpendicular to the crank arm direction. It can be seen as That is, this means that the direction of displacement of the second and fourth journal parts caused by torsional vibration of the crankshaft occurs in a direction perpendicular to the direction of the crank arm.

Note that the amount of displacement generated in the second and fourth journal parts 3B and 3D of the crankshaft 1 changes fluidly and periodically according to the crank angle.
The maximum torque is reached when the maximum torque is applied to the crankshaft 1, that is, when the crank angle is within the range of 30° to 60° after passing the top dead center.

The vibration prevention device for an in-line four-cylinder engine of the present invention was developed based on the above-mentioned theoretical background, and is based on the displacement of the second and fourth journal portions caused by torsional vibration of the crankshaft. The excitation force is reduced by providing appropriate shock absorbing means in the second and fourth bearing portions, thereby attempting to more effectively prevent engine vibrations caused by torsional vibrations of the crankshaft. The present invention will be explained below based on first and second embodiments.

(Embodiment) FIG. 3 is a longitudinal cross-sectional view of the second bearing portion 7B of the cylinder block 13 of the in-line four-cylinder automobile engine equipped with the vibration prevention device _Z1 according to the first embodiment of the present invention. ing. This vibration prevention device Z ₁ includes an oil passage 1 for lubricating the crankshaft that communicates with the main oil gear rally 10 in the cylinder block 13.
One end of 1 is connected to the crank arm center line on the inner circumferential surface of the bearing bush 9, which is inclined at 60 degrees in the direction of rotation of the crankshaft with respect to the sliding center line _L0 of the piston 4B.
Straight line perpendicular to L ₁ (hereinafter referred to as the excitation direction line)
Openings are made at two positions on _L2 (ie, positions where maximum torsional vibration occurs). Furthermore, this second
The oil passage 11 having the same structure as that formed in the bearing part 7B is also provided in the fourth bearing part 7D (not shown). When the oil passage 11 is opened at the position where the maximum torsional vibration occurs and in the direction of the amplitude of the torsional vibration, a predetermined pressure is applied from each opening end 11a, 11a of the oil passage 11 to the second journal portion 3B and the second journal portion 3B. The excitation force transmitted to the second and fourth journal parts 3B and 3D can be effectively attenuated by the pressure of the oil discharged toward the axis of the four journal part 6D. Therefore, it is possible to prevent the excitation force generated by the torsional vibration generated in the crankshaft 1 from being transmitted from the second and fourth journal parts 3B and 3D to the second and fourth bearing parts 7B and 7D. can be prevented. That is, in this first embodiment, the oil passages 11 which are opened in the direction of the vibration direction L ₂ at two positions on the bearing metal 9 and on the vibration direction line L ₂ act as the shock absorbing means X. It's forcing me.

FIG. 4 shows a cylinder block 13 of an in-line four-cylinder automobile engine equipped with a vibration prevention device _Z2 according to a second embodiment of the present invention. This second
The vibration prevention device Z ₂ of the embodiment is such that the vibration prevention device Z ₁ of the first embodiment is located on the inner surface of the bearing bush 9 of the second and fourth bearing portions 7B and 7D and on the vibration direction line L _{2 .}
Torsional vibration occurs in the second and fourth journal parts 3B and 3D due to the pressure of oil discharged from the oil passage 11 toward the axis of the journal part by opening one end of the oil passage 11 at the upper two positions. In contrast, the excitation direction line
Clearances 12, 12 larger than other circumferential parts are formed between the bearing bush 9 and the second and fourth journal parts 3B, 3D in the _L2 direction, respectively,
The second and fourth journal parts 3B, 3D are prevented from coming into direct contact with the second and fourth bearing parts 7B, 7D due to their torsional displacement, and the vibrations caused by torsional vibration of the crankshaft are prevented. The excitation force is the second and fourth
While suppressing the transmission to the bearing parts 7B and 7D as much as possible, the oil pressure supplied into the clearance 12 causes the second and fourth journal parts 3
Some attempt to attenuate the amount of displacement in B and 3D as well. That is, the vibration prevention device Z ₂ of this second embodiment
is the clearance 12,1 provided on the excitation direction line.
2 is made to act as a shock absorbing means X.

In FIG. 4, reference numeral 10 is a main oil gear rally, and 11 is an oil passage.

Further, each member in FIGS. 3 and 4 is given a reference numeral corresponding to each member in FIG. 1, and the explanation thereof is omitted.

(Effects of the Invention) The vibration prevention device for an in-line 4-cylinder engine of the present invention is provided in an in-line 4-cylinder engine in which a crankshaft to which a flywheel is connected to one end is supported by bearings at five bearing portions. Appropriate shock absorbing means are provided in the second and fourth bearing parts, which are susceptible to large excitation forces, and at the positions in the excitation direction when the maximum torque is generated on the crankshaft. This has the effect of effectively damping the excitation force caused by the torsional vibration of the crankshaft generated in the engine, thereby reducing engine vibration and engine noise as much as possible.

[Brief explanation of the drawing]

Fig. 1 is a conceptual diagram of torsional vibration generation in the crankshaft of an in-line four-cylinder engine, Fig. 2 is a torsional displacement diagram of the crankshaft shown in Fig. 1, and Fig. 3 is a vibration prevention device according to the first embodiment of the present invention. FIG. 4 is a vertical sectional view of main parts of an automobile engine equipped with
FIG. 1 is a vertical cross-sectional view of a main part of an automobile engine equipped with a vibration prevention device according to an embodiment. 1...Crankshaft, 6...Flywheel, 7
B...Second bearing part, 7D...Fourth bearing part, X...
Shock buffering means.

Claims (1)

[Claims] 1. In an in-line 4-cylinder engine in which a crankshaft with a flywheel connected to one end is supported by bearings at five locations, the second and fourth shafts in the direction orthogonal to the crank arm when the maximum torque is generated on the crankshaft. A vibration prevention device for an in-line four-cylinder engine, characterized in that a bearing section is provided with a shock absorbing means.