JPH10281137A - Journal bearing device for internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve support force of a crank shaft by an oil film so as to reduce stroke noise of the crank shaft by providing a bearing in which an oil groove deflected from a width direction center position of a bearing surface in a width direction for a prescribed shift rate. SOLUTION: The case (a) where the shift direction of an oil groove 10 is set to a direction separated from the centroid G, and the case (b) where the shift direction of the oil groove 10 is set to a direction approaching the centroid G, are shown. Oil film reaction applied from journal bearings 3, 5, 7 are set to F1, F3, F5 respectively, and a moment is found out. As a result, those relation are set to F1.δ1a <F1.δ1b , F3.δ3a <F3.δ3b , F5.δ5a <F5.δ5b , and suppressing effect of behavior of the crank shaft is improved in the case (b). The shift direction of the oil groove 10 is deflected so as to approach a centroid position as possible, and thereby, it is possible to improve reducing effect of stroke noise.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a journal bearing device for supporting a crankshaft in an internal combustion engine for an automobile or the like, and more particularly, to a journal bearing for an internal combustion engine improved so that the supporting force of the crankshaft by an oil film can be increased. Related to the device.

[0002]

2. Description of the Related Art In a journal bearing that supports a crankshaft of an internal combustion engine such as an engine for an automobile, an oil film is interposed in a clearance provided between the crankshaft and the bearing. It is designed to float and support it.

In this type of journal bearing, it is preferable to set the clearance for forming the oil film as large as possible from the viewpoint of securing the circulation of the lubricating oil and reducing the friction loss and the amount of wear. However, if the clearance is too large, when a load is changed in a direction perpendicular to the axis of the crankshaft, eccentricity of the axis occurs, and the crankshaft collides with the bearing surface to generate a tapping sound. For this reason, usually, the clearance within a range in which the friction loss and the wear amount are reduced as much as possible and the hitting sound is not deteriorated is experimentally obtained and set.

[0004] On the other hand, in order to supply lubricating oil for forming an oil film, an oil groove is usually provided at the center of the bearing surface of the journal bearing. Further, since the portion with the oil groove does not have the ability to support the crankshaft, the hitting sound is more likely to be deteriorated as compared with the case without the oil groove. For this reason, there is known a prior art in which an oil groove is not provided on the side receiving a large external force, and an oil groove is provided only on a half circumference of the bearing surface on the other side (Japanese Patent Laid-Open No. 55-10106). .

[0005]

However, from the viewpoint of sufficiently supplying lubricating oil so as not to cause an oil shortage, it is desirable to provide an oil groove all around the bearing surface. There is also a problem that the supporting force is weakened and the hitting sound is deteriorated. As described above, when the oil groove is provided in the journal bearing, the demand for sufficient supply of the oil and the reduction of the hitting sound are incompatible with each other.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to solve the above-mentioned problems of the prior art and to increase the supporting force of the crankshaft by the oil film while ensuring sufficient lubricating oil supply by the oil groove. It is an object of the present invention to provide a journal bearing for an internal combustion engine that can reduce the hammering sound.

[0007]

In order to achieve the above object, the present invention provides a journal bearing device having a plurality of bearings for supporting a crankshaft of an internal combustion engine by the pressure of an oil film formed on a bearing surface. A bearing having an oil groove on the bearing surface deviated by a predetermined shift amount δ in the width direction from the center position in the width direction of the bearing surface is provided.

According to the present invention, it is possible to reduce the noise of the crankshaft by increasing the supporting force of the crankshaft by the oil film while ensuring a sufficient supply of the lubricating oil by the oil groove.

In the present invention, preferably, the oil groove is deviated in a direction approaching the center of gravity with reference to the position of the center of gravity of the crankshaft, whereby the effect of further reducing the hitting sound is obtained.

The shift amount δ is preferably set so as to approach (LB) / 2, where L is the bearing width and B is the oil groove width.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a journal bearing for an internal combustion engine according to the present invention will be described below with reference to the accompanying drawings. FIG. 1 shows a crankshaft 1 supported by a journal bearing according to the invention. 2a, 2b, 2
c and 2d are crankpins, 3, 4, 5, 6, and 7 are journal bearings. In this case, an oil groove 10 shifted to one side from the center of the bearing is provided in the journal bearings 3 and 7 at both ends close to the front shaft 8 and the rear shaft 9 on which the flywheel is mounted, and in the center journal bearing 5. Journal bearing. In this embodiment, the journal bearings 4 and 6 have no oil grooves.

FIG. 2 shows a journal bearing 3 having an oil groove and a journal bearing 4 having no oil groove. The journal bearings 3, 4 are respectively semi-cylindrical sliding bearings 12a, 12a.
b, 13a and 13b. Of these, the oil grooves 1 are provided on the bearing surfaces of the sliding bearings 12a and 12b.
0 is formed. An oil hole 14 communicating with the oil groove 10 is provided. The oil hole 14 is located at a position deviated according to the shift amount of the oil groove 10. In addition,
Oil holes 15 are also formed in the sliding bearings 13a and 13b having no oil grooves to supply oil to the bearing surfaces.

Next, the operation of the journal bearing according to this embodiment will be described. FIG. 3 is a diagram schematically showing the operation of the oil film supporting the crankshaft 1 in the journal bearing. In FIG. 3, the hatched portion indicates a region where the oil that forms the oil film exists. Here, assuming that the load F acts on the crankshaft 1, even if the load F acts on the crankshaft 1 perpendicularly due to the action of oil being caught by the rotation of the crankshaft 1, the axis moves obliquely. Eccentric. The reaction force from the oil film at this time is decomposed into a component Fn in the eccentric direction and a component Ft in the direction perpendicular to the eccentric direction, and the respective components are obtained by the short bearing approximation method. become.

[0014]

(Equation 1) Here, ε: the amount of eccentricity ω: the rotational speed of the crankshaft Ψ: the revolution speed of the crankshaft L: the bearing width r: the radius of the crankshaft μ: the viscosity of the oil Cr: the initial clearance n: the eccentricity (n = ε / Cr) ). From the expressions (1) and (2), the oil film reaction force in the journal bearing is proportional to the cube of the bearing width L.

Next, consider the width B of the oil groove. Since oil film reaction does not occur in the oil groove part, in the case of a journal bearing having an oil groove,

[0016]

(Equation 2) It can be considered equivalent to two parallel bearings without an oil groove having a bearing width L '. Therefore, the oil film reaction force Fn ′ in a journal bearing having an oil groove is represented by Fn, where the oil film reaction force without an oil groove is Fn.

[0017]

(Equation 3) become.

Next, in the case of a journal bearing having an oil groove having a width B as shown in FIG.

[0019]

(Equation 4) It can be considered as a combination of bearings without oil grooves having bearing widths L ′ and L ″. Therefore, if the oil film reaction force is F '',

[0020]

(Equation 5) Becomes

Therefore, in order to obtain a large oil film reaction force as compared with the conventional oil grooved bearing, it is necessary to use Fn ″> Fn ′

[0022]

(Equation 6) Expand this,

[0023]

(Equation 7) It can be seen that the shift amount δ satisfying the following condition should be selected. Therefore, from equation (8),

[0024]

(Equation 8) You can choose from the range.

In the equation (7), if the effect of the second term on the right side is small, it can be ignored.

[0026]

(Equation 9) Thus, the minimum required shift amount can be obtained.

FIG. 5 is a diagram showing the relationship between the effect of increasing the supporting force of the oil film and the shift amount δ. In this case, FIG.
Indicates the effective range in which both sides of equation (9) are divided by L. FIG. 5B shows the effective range in consideration of the minimum shift amount δ based on the equation (10). From this figure, when setting the shift amount δ, as long as the strength of the narrower bearing surface permits the partition by the oil groove 10, the shift amount δ should be set as large as possible in the range of the expression (9). I just need.

Next, FIG. 6 schematically shows the crankshaft system of FIG.
7 shows a situation in which the oil film reaction force of No. 7 acts as a moment around the center of gravity position G of the crankshaft system.

FIG. 6A shows the case where the shift direction of the oil groove 10 is set in a direction away from the center of gravity G, and FIG.
The case where the shift direction of 0 is set to the direction approaching the center of gravity G is shown. When the moments are calculated with the oil film reaction forces received from the journal bearings 3, 5, and 7 as F1, F2, and F3, respectively, F1.delta.1a <F1.delta.1b F3.delta.3a <F3.delta.3b 6 (b) shows that the effect of suppressing the behavior of the crankshaft is higher. Therefore, in relation to the center of gravity G, the shift direction of the oil groove 10 is deviated so as to be as close as possible to the position of the center of gravity, whereby the effect of reducing the hitting sound can be further enhanced.

[0030]

As is apparent from the above description, according to the present invention, there is provided a bearing having an oil groove deviated by a predetermined shift amount δ in the width direction from the center position in the width direction of the bearing surface on the bearing surface. Therefore, while ensuring a sufficient supply of lubricating oil by the oil groove, the supporting force of the crankshaft by the oil film can be increased to reduce the noise of the crankshaft.

[Brief description of the drawings]

FIG. 1 is a side view showing an embodiment of a journal bearing device for an internal combustion engine according to the present invention.

FIG. 2 is a perspective view of a journal bearing.

FIG. 3 is an explanatory diagram of an action of an oil film reaction force of a journal bearing.

FIG. 4 is a diagram showing an oil groove and a shift amount.

FIG. 5 is a diagram showing an effective range of a shift amount effective for improving an oil film reaction force.

FIG. 6 is a schematic diagram of the crankshaft system showing the position of the center of gravity in the crankshaft system and the moment due to the oil film reaction force.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Crankshaft 2a-2d Crank pin 3 Journal bearing with oil groove 4 Journal bearing without oil groove 5 Journal bearing with oil groove 6 Journal bearing without oil groove 7 Journal bearing with oil groove 10 Oil groove 14 Oil hole

Claims (3)

[Claims] 1. A journal bearing device comprising a plurality of bearings for supporting a crankshaft of an internal combustion engine by the pressure of an oil film formed on a bearing surface, wherein a predetermined shift amount δ in a width direction from a center position in a width direction of the bearing surface.
A journal bearing device for an internal combustion engine, comprising: a bearing having an oil groove deviated only on a bearing surface. 2. The journal bearing device for an internal combustion engine according to claim 1, wherein the oil groove is deviated in a direction approaching the center of gravity with reference to the position of the center of gravity of the crankshaft. 3. The shift amount δ is set so as to approach (LB) / 2, where L is the bearing width and B is the oil groove width. Journal bearing device for internal combustion engines.