JP2011163213A - Bearing for internal combustion engine - Google Patents

Abstract

Provided is a diesel engine bearing capable of improving fuel efficiency without causing a lot of useless flow of a lubricant pump without flowing a lot of useless lubricant to a main bearing and a connecting rod bearing. .
An inner diameter on a low load side with respect to a main bearing is formed smaller than an inner diameter on a high load side, and an inner diameter on a low load side with respect to a connecting rod bearing is formed smaller than an inner diameter on a high load side.
[Selection] Figure 3

Description

  The present invention relates to a bearing for an internal combustion engine.

  A general internal combustion engine such as a diesel engine has a structure as shown in FIG. A connecting rod bearing 2a as shown in FIG. 9 is used in the A portion, and a main bearing 5a as shown in FIG. 10 is used in the B portion (see, for example, Patent Documents 1 and 2).

JP 2003-222119 A JP 2009-167805 A

  By the way, in a diesel engine, since the maximum number of rotations is low, the load to the connecting rod bearing 2a and the main bearing 5a is large due to the combustion pressure, and small due to inertial force. Therefore, the upper load is large in the connecting rod bearing 2a, and the lower load is large in the main bearing 5a. Originally, it is desirable to flow a large amount of lubricating oil to the larger load, and to form a lubricating oil film reliably in a portion where the surface pressure due to the load is high, and to cool sufficiently.

  However, conventionally, both the connecting rod bearing 2a and the main bearing 5a have the same upper and lower inner diameters, so that a large amount of lubricating oil flows also to a portion having a low load and a small amount of lubricating oil. In other words, in order to allow sufficient lubricating oil to flow to the higher load side, a large amount of lubricating oil was unnecessarily flown to the lower load side. For this reason, the lubricating oil pump has to be rotated unnecessarily, resulting in a deterioration in fuel consumption.

  The present invention has been made in view of the above points, and the object of the present invention is to rotate the lubricating oil pump unnecessarily without flowing a large amount of lubricating oil to the main bearing and the connecting rod bearing. Therefore, it is an object of the present invention to provide a bearing for an internal combustion engine that can improve fuel consumption as a result.

  In order to solve the above-mentioned problems, a bearing for an internal combustion engine according to the present invention is mainly provided in a bearing hole of a crank journal portion formed by a lower surface portion of a crank journal supporting partition wall of a cylinder block and a bearing cap integrally attached thereto. A bearing of an internal combustion engine in which a bearing is attached and a connecting rod bearing is attached to a bearing hole of a crank pin formed at the large end of the connecting rod, and the inner diameter of the main bearing on the low load side due to the combustion pressure is set on the high load side. The inner diameter of the connecting rod bearing is smaller than the inner diameter of the high load side.

  The main bearing includes an upper main bearing having a low load and a lower main bearing having a high load, and a difference between an inner diameter of the upper main bearing and an outer diameter of the crank journal portion is determined by the lower main bearing. It is preferable that the difference between the inner diameter and the outer diameter of the crank journal portion is ½.

  The connecting rod bearing includes a lower connecting rod bearing having a low load and an upper connecting rod bearing having a high load, and a difference between an inner diameter of the lower connecting rod bearing and an outer diameter of the crank pin is an inner diameter of the upper connecting rod bearing. And 1/2 of the difference between the outer diameter of the crank pin and the crank pin.

  According to the above configuration, in the main bearing having a low upper load, the gap between the crank journal and the upper main bearing can be reduced to reduce the amount of lubricating oil, and in the connecting rod bearing having a low lower load, the crank pin and the lower bearing can be reduced. The gap with the side connecting rod bearing is reduced, and the amount of lubricating oil can be reduced.

  According to the present invention, it is not necessary to turn the lubricating oil pump unnecessarily without flowing a lot of lubricating oil to the main bearing and the connecting rod bearing, and as a result, fuel consumption can be improved.

FIG. 1 is a sectional view of an engine of a diesel engine incorporating a main bearing and a connecting rod bearing according to an embodiment of the present invention. FIG. 2 is a schematic view showing the relationship between a part of the crankshaft and the main bearing and connecting rod bearing. FIG. 3 is a schematic cross-sectional view showing the relationship between the main bearing and the crank journal portion according to the embodiment of the present invention. FIG. 4 is a schematic cross-sectional view showing the relationship between the connecting rod bearing, the connecting rod large end, and the crank pin according to the embodiment of the present invention. FIG. 5 is a diagram showing the behavior of the crankpin shaft center in the connecting rod bearing. FIG. 6 is a diagram showing the behavior of the crank journal axis in the main bearing. FIG. 7 is a diagram showing a lemon-shaped image of the bearing. FIG. 8 is a cross-sectional view of a typical diesel engine. 9A and 9B are diagrams showing a general connecting rod bearing, in which FIG. 9A is a front view and FIG. 9B is a plan view seen from the inside. 10A and 10B are diagrams showing a general main bearing, in which FIG. 10A is a front view and FIG. 10B is a plan view viewed from the inside.

  A preferred embodiment of the present invention will be described with reference to the accompanying drawings.

  As shown in FIG. 1, an internal combustion engine such as a diesel engine changes the linear reciprocating motion of the piston 13 caused by the explosion pressure of the engine to the rotational motion of the crankshaft 4 (see FIG. 2) via the connecting rod 3, thereby providing continuous power. Is supposed to occur. In FIG. 1, 1 is a cylinder block, 12 is a cylinder head, 14 is a piston pin, 15 is a water jacket, 16 is an intake port, 17 is an intake valve, and 18 is an oil pan.

  As shown in FIG. 2, the crankshaft 4 has a crank journal portion 41 and a crankpin 40 connected in series via a crank arm 42 and a balance weight 43, and the crank journal portion 41 is supported by the main bearing 5. The crank pin 40 is supported by the connecting rod bearing 2. The main bearing 5 and the connecting rod bearing 2 are made of sliding bearings.

  As shown in FIG. 3, a semicircular bearing cap 19 is coupled to the lower surface portion of the crank journal support partition wall 10 of the cylinder block 1 with a bolt (not shown), and the bearing hole 45 of the crank journal portion 41 has a crank hole. The curved surface 10 a of the journal support partition 10 and the curved surface 19 a of the bearing cap 19 are formed.

  The main bearing 5 is configured by abutting a half-cylindrical upper main bearing 50 and a half-cylindrical lower main bearing 51. The upper main bearing 50 is integrally attached to the curved surface 10 a of the crank journal support partition wall 10, the lower main bearing 51 is integrally attached to the curved surface 19 a of the bearing cap 19, and the crank journal portion 41 is connected to the main bearing 5. Is rotatably supported by. In the upper main bearing 50, an oil supply hole 52 is formed in the radial direction, and an annular oil groove 53 is formed on the inner side.

  As shown in FIG. 4, a semicircular bearing cap 31 is coupled to the semicircular portion of the connecting rod large end portion 30 with a bolt 32 and a nut 33, and the bearing hole 46 of the crank pin 40 is connected to The curved surface 30 a and the curved surface 31 a of the bearing cap 31 are formed.

  The connecting rod bearing 2 is also configured by abutting a half cylindrical upper connecting rod bearing 20 and a half cylindrical lower connecting rod bearing 21. The upper connecting rod bearing 20 is integrally attached to the curved surface 30 a of the connecting rod large end 30, the lower connecting rod bearing 21 is integrally attached to the curved surface 31 a of the bearing cap 31, and the crank pin 40 is connected by the connecting rod bearing 2. It is supported rotatably.

  As shown in FIG. 3, the main bearing 5 is formed so that the inner diameter of the upper main bearing 50 is smaller than the inner diameter of the lower main bearing 51. As shown in FIG. 4, the connecting rod bearing 2 is formed such that the inner diameter of the lower connecting rod bearing 21 is smaller than the inner diameter of the upper connecting rod bearing 20. 3 and 4, the difference between the inner diameters is extremely larger than the actual one for convenience of explanation.

  As shown in FIG. 2, the crankshaft 4 has an oil hole 41a extending in the radial direction of the crank journal portion 41 therein, and an oil hole 44 extending obliquely from the oil hole 41a toward the crank pin 40. Is formed. Lubricating oil is supplied between the main bearing 5 and the crank journal portion 41 through an oil supply hole 52 and an oil groove 53 of the upper main bearing 50 from an oil passage 11 formed in the crank journal support partition wall 10 from an oil gallery (not shown). Further, lubricating oil is supplied between the connecting rod bearing 2 and the crank pin 40 through the oil hole 44, and an oil film is formed.

By the way, since the lubricating oil inflow amount (= lubricating oil outflow amount) Q to the bearing is proportional to the clearance area between the shaft and the bearing, the lubricating oil outflow amount Q from the upper bearing or the lower bearing is expressed by the following equation: Become.
Q = K × π × D1 × {(D2−D1) / 2}
Where K: proportionality constant
π: Circumference ratio
D1; shaft outer diameter (unit: mm, the same applies hereinafter)
D2: Bearing inner diameter (unit: mm, the same applies hereinafter)

  Since the shaft outer diameter D1 is constant, if the bearing inner diameter D2 is changed by the upper and lower bearings, the lubricating oil inflow amount (= lubricating oil outflow amount) Q to the bearing can be changed by the upper and lower bearings.

  Therefore, by making the inner diameter D2 of the lower connecting rod bearing 21 on the low load side smaller than the inner diameter D2 of the upper connecting rod bearing 20 on the higher load side, the amount of lubricating oil on the lower load side can be reduced. Further, by making the inner diameter D2 of the upper main bearing 50 on the low load side smaller than the inner diameter D2 of the lower main bearing 51 on the high load side, the amount of lubricating oil on the lower load side can be reduced.

Conventionally, the clearance is a bearing inner diameter D2-shaft outer diameter D1≈shaft outer diameter D1 / 1000.
It has become.

  FIG. 5 shows the behavior of the crankpin shaft center in the connecting rod bearing. In the figure, the intersection of the centers of the circles indicates that the axial center of the connecting rod bearing 2 and the axial center of the crankpin 40 coincide with each other, and S between the outer circle and the thick line indicating the inner behavior is the bearing clearance ( Oil film thickness). When the connecting rod 3 is pushed downward by the combustion pressure of the engine and the connecting rod bearing 2 is also pushed, the upper oil film thickness (the oil film thickness between the crankpin 40 and the upper connecting rod bearing 20) is reduced to the lower oil film. Compared to the thickness (the oil film thickness between the crank pin 40 and the lower connecting rod bearing 21), the thickness is reduced by ½. FIG. 6 shows the behavior of the crank journal axis in the main bearing as in FIG. 5. When the connecting rod 3 is pushed downward, the crank journal 41 is pushed downward together with the crank pin 40. The oil film thickness (the oil film thickness between the crank journal portion 41 and the lower main bearing 51) is larger than the upper oil film thickness (the oil film thickness between the crank journal portion 41 and the upper main bearing 50). It becomes thinner by 1/2. 5 and 6, it can be determined that the bearing inner diameter D2-shaft outer diameter D1 on the low load side should be ½ of the bearing inner diameter D2-shaft outer diameter D1 on the higher load side.

  For this reason, in this embodiment, the difference between the inner diameter of the upper main bearing 50 with a low load and the outer diameter of the crank journal part 41 is the difference between the inner diameter of the lower main bearing 51 with a higher load and the outer diameter of the crank journal part 41. The amount of lubricating oil on the low load side is reduced to 1/2. Further, the difference between the inner diameter of the lower connecting rod bearing 21 having a low load and the outer diameter of the crank pin 40 is set to ½ of the difference between the inner diameter of the upper connecting rod bearing 20 having a higher load and the outer diameter of the crank pin 40. The amount of lubricating oil on the lower side is reduced.

  If the inner diameter is different between the upper and lower sides, the step of the boundary is anxious, but the actual inner diameter of the bearing is not a perfect circle but a lemon shape as shown in FIG. That is, the bearing hole 8c formed by the upper bearing 8a and the lower bearing 8b has a gap with the shaft 8d that gradually increases from the center axis X of the shaft 8d to the mating surface Y of the upper bearing 8a and the lower bearing 8b. It has a lemon shape. This is in order to avoid the adverse effects caused by the difference in the assembly even when the inner diameter is the same. For this reason, there is no problem even if the inner diameter of the bearing is changed up and down.

  As described above, according to the present invention, the inner diameter of the upper main bearing 50 on the lower load side due to the combustion pressure of the main bearing 5 is formed smaller than the inner diameter of the lower main bearing 51 on the higher load side. The clearance S1 with the crank journal portion 41 can be made smaller than the clearance S2 between the lower main bearing 51 and the crank journal portion 41, and the amount of lubricating oil flowing to the upper main bearing 50 can be reduced. Similarly, the inner diameter of the lower connecting rod bearing 21 on the low load side due to the combustion pressure of the connecting rod bearing 2 is made smaller than the inner diameter of the upper connecting rod bearing 20 having a higher load, and a clearance S4 between the lower connecting rod bearing 21 and the crank pin 40 is formed. The amount of lubricating oil flowing to the lower connecting rod bearing 21 can be reduced by making it smaller than the gap S3 between the upper connecting rod bearing 20 and the crank pin 40.

  As described above, according to the present invention, it is possible to reduce the amount of lubricating oil to the slide bearing (con rod bearing, main bearing) very easily and without any problem in reliability. Thereby, it is not necessary to rotate the lubricating oil pump unnecessarily, and as a result, fuel consumption can be improved.

DESCRIPTION OF SYMBOLS 1 Cylinder block 2 Connecting rod bearing 3 Connecting rod 4 Crankshaft 5 Main bearing 10 Crank journal support partition wall 19 Bearing cap 10a, 19a Curved surface 20 Upper connecting rod bearing 21 Lower connecting rod bearing 30 Connecting rod large end 30a Curved surface 31 Bearing cap 31a Curved surface 40 Crank Pin 41 Crank Journal 45, 46 Bearing Hole 50 Upper Main Bearing 51 Lower Main Bearing

Claims (3)

  Crank pin bearing formed at the connecting rod large end by attaching the main bearing to the bearing hole of the crank journal formed by the lower surface portion of the crank journal supporting partition wall of the cylinder block and the bearing cap integrally attached thereto. In a bearing of an internal combustion engine in which a connecting rod bearing is attached to the hole, an inner diameter on a low load side due to combustion pressure of the main bearing is formed smaller than an inner diameter on a high load side, and the low load side of the connecting rod bearing is formed. A bearing for an internal combustion engine, characterized in that the inner diameter is smaller than the inner diameter on the higher load side.   The main bearing includes an upper main bearing having a low load and a lower main bearing having a high load, and a difference between an inner diameter of the upper main bearing and an outer diameter of the crank journal portion is an inner diameter of the lower main bearing. 2. A bearing for an internal combustion engine according to claim 1, wherein the bearing is half the difference between the outer diameter of the crank journal portion and the outer diameter of the crank journal portion.   The connecting rod bearing comprises a lower connecting rod bearing having a low load and an upper connecting rod bearing having a high load. 2. A bearing for an internal combustion engine according to claim 1, wherein the bearing is 1/2 of the difference from the outer diameter of the crank pin.

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