JP5504751B2 - Crankshaft roller bearing - Google Patents

Description

  The present invention relates to a roller bearing for a crankshaft used for an automobile engine or the like.

  Usually, a crankshaft of an automobile engine is supported by a slide bearing (Patent Documents 1 and 2).

  As shown in FIG. 7, the plain bearing 70 formed in a cylindrical shape is attached to a bearing hole 7 formed by the cylinder block 3 and the bearing cap 4 and supports the journal portion 6 of the crankshaft. The crankshaft has a plurality of crankpins 71 connected in series via a crank arm 72, a balance weight 73, and a journal portion 6, and has an output flange (not shown) at one end and a complementary at the other end. And a mounting shaft 74 to which a machine and a camshaft driving pulley (not shown) are attached. Lubricating oil from an oil pump (not shown) is supplied to the gap between the journal part 6 and the slide bearing 70 through the oil supply hole 60 of the journal part 6, and a wedge oil film is formed in the gap as the journal part 6 rotates. Thus, an oil film pressure is generated to support the journal portion 6.

  Since the slide bearing 70 is made of an oil film as a damper, it absorbs that the journal portion 6 of the crankshaft strikes the slide bearing 70 violently, and an impact load caused by an explosion pressure or the like is suppressed.

JP 2001-241442 A JP 2004-245388 A

  However, the sliding bearing 70 has a large sliding resistance due to contact between metals without an oil film. In particular, at the moment when the engine is started, no oil film is formed because no hydraulic pressure is applied, and the metals are in contact with each other. If the engine starts repeatedly in this state, the journal section 6 and the plain bearing 70 are It will wear out. In addition, the sliding bearing 70 floats with the lubricating oil during operation, but the occurrence of viscous resistance of the lubricating oil is inevitable. If it is a roller bearing, the viscous resistance can be ignored and it rotates smoothly, so there is no sliding resistance even when the engine is started, and there is an advantage that the starter motor can be made smaller by making it easier to start the engine. In addition, as described above, the sliding bearing 70 is floated by the lubricating oil even during operation, but the viscous resistance of the lubricating oil is unavoidable, whereas the roller bearing has a rolling friction coefficient of the viscous resistance of the lubricating oil. Therefore, the friction is less than that of the plain bearing 70.

  For this reason, recently, in order to reduce the friction of the crankshaft, research for adopting a roller bearing instead of the slide bearing 70 has been conducted. However, in the case of a roller bearing, since there is no interference member in which the oil film becomes a damper unlike the slide bearing 70, the journal portion 6 of the crankshaft hits the inner ring of the roller bearing and an impact load is generated. This impact load is transmitted to the cylinder block 3 through the inner ring, roller and outer ring of the roller bearing. As a result, the roller bearing is significantly noisier than the plain bearing 70.

  The present invention has been made in view of such points, and an object of the present invention is to provide a roller bearing for a crankshaft that has a low-cost and simple structure, has low friction, suppresses an impact load, and does not increase noise. There is to do.

In order to solve the above problems, the present invention provides a crankshaft roller bearing that is mounted in a bearing hole formed by a cylinder block and a bearing cap and rotatably supports a journal portion of the crankshaft. An outer ring fitted with a gap between the outer ring, a plurality of rollers arranged circumferentially on the inner circumferential surface of the outer ring and in contact with the journal portion so as to be rotatable, and formed in the cylinder block. An oil passage for supplying oil to form an oil film damper, and an outer peripheral surface or an inner peripheral surface formed along the circumferential direction are recessed above and below the outer peripheral surface of the outer ring or the inner peripheral surface of the bearing hole. The outer ring cannot move in the circumferential direction and the piston reciprocates between the recessed portion formed between the outer ring and the cylinder block or the bearing cap. And a fixing pin that is interposed so as to be movable, the recess has an axial wall portion which has a circumferentially opposite ends circumferential wall portion, the oil passage, the upper recess of the recess The cylinder block is formed so as to supply the lubricating oil as it is.

  According to the above configuration, when the engine is started, the friction is small due to the rolling friction by the roller bearing, and during operation, oil is supplied to the gap between the outer ring of the roller bearing and the bearing hole to form an oil film damper. Due to the damping effect of oil, cushioning can be provided against intense movement of the crankshaft during engine rotation, and impact loads can be absorbed. In addition, the bearing hole for attaching the roller bearing to the cylinder block and the bearing cap only needs to have a larger diameter than the outer ring of the roller bearing so as to form a gap, so that it has a simple structure and can be manufactured at low cost.

  According to the roller bearing for a crankshaft of the present invention, it is possible to reduce the friction with a low-cost and simple structure, reduce the impact load, and reduce the engine noise.

FIG. 1A is a sectional view showing a state in which a crankshaft roller bearing according to an embodiment of the present invention is installed in a bearing hole, and FIG. 1B is a perspective view of a roller retainer. 2A is a cross-sectional view taken along the line AA in FIG. 1, and FIG. 2B is a perspective view showing a part of the outer ring. FIG. 3 is a cross-sectional view showing a state where a crankshaft roller bearing according to another embodiment of the present invention is installed in a bearing hole. 4A is a cross-sectional view taken along the line BB in FIG. 3, and FIG. 4B is a perspective view showing a part of a recess formed in the outer ring and a fixing pin. FIG. 5 is an explanatory diagram showing the relationship between the gap and the oil pressure in the embodiment shown in FIGS. 1 and 2. FIG. 6 is an explanatory diagram showing the relationship between the gap and the oil pressure in another embodiment shown in FIGS. 3 and 4. FIG. 7 is a cross-sectional view showing a conventional crankshaft plain bearing.

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

  1 to 6, members having the same functions as those shown in the conventional example of FIG. 7 are described with the same reference numerals.

  1 and 2 show a first embodiment (hereinafter referred to as Embodiment 1). A semicircular recess is provided in the cylinder block 3 and the bearing cap 4, and the recesses are brought into contact with each other to connect the cylinder block 3 and the bearing cap 4 with a bolt 5 to form a bearing hole 7. A roller bearing 1 that rotatably supports the journal portion 6 of the crankshaft is disposed in the bearing hole 7. The roller bearing 1 includes an outer ring 10, a large number of rollers 16 that can rotate within the outer ring 10, and a retainer 17 that rotatably holds these rollers 16.

  As shown in FIG. 1 (B), the retainer 17 is a thin cylindrical support body in which a mounting hole 17a for fitting the roller 16 is formed, and a large number of rollers 16 are arranged at predetermined intervals in the circumferential direction of the journal portion 6. It is configured to be rotatably supported with a gap therebetween. The roller 16 has substantially the same diameter and length, but can withstand heavy loads if the length is longer than the diameter. On the inner peripheral surface 14 of the outer ring 10, raceway grooves 15 that guide the rollers 16 in a rotatable manner are formed in the circumferential direction. On the other hand, these rollers 16 are rotatably in contact with the outer peripheral surface of the journal portion 6 whose hardness is increased by induction hardening or the like. That is, a roller 16 is rotatably interposed between the journal portion 6 and the outer ring 10, and the journal portion 6 is rotatable relative to the outer ring 10 via the roller 16. In FIG. 1, the rollers 16 have a double-row configuration, but may have a single-row configuration.

  The inner diameter of the bearing hole 7 is formed to be larger than the outer diameter of the outer ring 10 of the roller bearing 1, and an annular gap S is formed between the bearing hole 7 and the outer ring 10. 7 is fitted. In FIGS. 1 and 2, the gap S is exaggerated.

  The fixing pin 2 is attached to the outer peripheral surface 11 of the outer ring 10 so as to protrude upward, and the tip of the fixing pin 2 is fitted into a fitting hole 31 formed in the cylinder block 3. The fixing pin 2 is a rotation stopper for preventing the outer ring 10 from rotating with respect to the cylinder block 3 and for positioning the outer ring 10 so as not to move in the axial direction of the journal portion 6. The diameter of the fitting hole 31 is made somewhat larger than the outer diameter of the fixed pin 2 so that the outer ring 10 can move in the reciprocating direction (vertical direction) of a piston (not shown). Note that the fixing pin 2 may be attached to the cylinder block 3 side to form a fitting hole in the outer ring 10.

  An oil passage 30 is formed in the cylinder block 3, and the tip of the oil passage 30 communicates with the annular gap S between the bearing hole 7 and the outer ring 10. The other end of the oil passage 30 is connected to an oil pump (not shown) driven by a crankshaft. Accordingly, a certain amount of lubricating oil is supplied to the gap S from the oil passage 30. The supplied lubricating oil overflows from both ends of the gap S and returns to an oil pan (not shown).

  The operation of the crankshaft roller bearing 1 configured as described above will be described.

  When the engine is started, the crankshaft (journal portion 6) is rotationally driven by a starter motor (not shown). When the journal portion 6 rotates, the plurality of rollers 16 in contact with the journal portion 6 rolls along the raceway groove 15 of the outer ring 10, so that the rotation can be smoothly supported only by the rolling friction at this time. At this time, since the oil pump (not shown) has not risen yet, no lubricating oil is supplied to the gap S, and no oil film damper is formed in the gap S. For this reason, when the piston (not shown) in the cylinder block 3 moves up and down, the journal portion 6 also moves up and down and the outer ring 10 collides with the bearing hole 7 via the roller 16, but the explosion load is small at the start. The impact is small, the noise is small and there is no problem.

  After the engine is started, an oil pump (not shown) is driven so that the lubricating oil is supplied to the gap S between the outer ring 10 of the roller bearing 1 and the bearing hole 7, and the gap S is filled with the lubricating oil. It is. For this reason, an oil film damper made of lubricating oil is formed, which becomes a cushion that absorbs an explosion load in the combustion stroke. That is, the damping effect which suppresses the fluctuation | variation by the explosion load in a combustion stroke using the viscosity of lubricating oil can be exhibited.

  Since the oil pump is driven even during operation, the lubricating oil continues to be supplied from the oil passage 30 to the gap S, and the gap S is filled with the lubricating oil. For this reason, the oil film damper formed of the lubricating oil absorbs the explosion pressure from the engine and does not generate an impact load on the journal portion 6, the roller 16, and the outer ring 10.

  In addition, although an oil film damper is formed in the gap S, the outer ring 10 does not rotate with respect to the cylinder block 3 by the fixing pin 2, so that the viscous resistance due to the oil film as in the conventional slide bearing 70 is ignored. The rotation of the journal portion 6 is rolling friction of the roller bearing 1, and the friction is small and smoothly rotated.

  Next, another embodiment (hereinafter referred to as Embodiment 2) will be described with reference to FIGS. Since the second embodiment is basically the same as the first embodiment, only the differences will be described.

  In the second embodiment, recesses 12 formed along the circumferential direction are provided on the outer circumferential surface 11 of the outer ring 10 fitted in the bearing hole 7 with a gap S therebetween, respectively. That is, as shown in FIG. 4, the lower concave portion 12 is formed over a load range of a lower angle θ (approximately 90 °) that receives the in-cylinder pressure load, and the upper concave portion 12 is an inertia of a piston or the like. Each is formed over the load range of the upper angle θ (substantially 90 °) receiving the force. Lubricating oil from the oil passage 30 is supplied as it is to the upper concave portion 12, but the lubricating oil supplied to the upper concave portion 12 overflows into the lower concave portion 12 along the outer peripheral surface 11 of the outer ring 10. And then supplied. Alternatively, the oil passage 30 may be branched to positively supply the lubricating oil to the lower recess 12.

  Further, the width (axial direction) of the recess 12 is about 50 to 90% of the width of the outer ring 10. As shown in FIG. 4B, a circumferential wall portion 12 a and an axial wall portion 12 b are formed on the outer circumferential surface 11 of the outer ring 10 by the recess 12.

  3 and 4, the recess 12 is provided on the outer peripheral surface 11 of the outer ring 10, but may be provided on the inner peripheral surface of the bearing hole 7 vertically.

  According to the second embodiment, the axial wall portion 12b becomes a step portion with respect to the gap S to form a throttle, so that the lubricating oil supplied to the gap S is less likely to flow out of the gap S, and the gap S The pressure of the lubricating oil inside becomes high. For this reason, the second embodiment can further increase the so-called damping effect by the oil, which suppresses the shaking due to the impact from the outside using the viscosity of the lubricating oil, as compared with the first embodiment. Further, since the circumferential wall portion 12a is formed, the lubricating oil in the recess 12 does not flow down in the circumferential direction (downward).

  Similarly to the first embodiment, the fixing pin 2 is attached to the recess 12 so as to protrude upward from the outer peripheral surface 11 of the outer ring 10, and the tip of the fixing pin 2 is inserted into the fitting hole 31 formed in the cylinder block 3. It is designed to fit. Similarly, the diameter of the fitting hole 31 is formed somewhat larger than the outer diameter of the fixed pin 2 so that the outer ring 10 can move in the reciprocating direction of the piston together with the fixed pin 2. Note that the fixing pin 2 may be attached to the cylinder block 3 side to form a fitting hole in the outer ring 10.

  During operation, the journal portion 6 rotates at a high speed, so that the outer ring 10 slightly rotates. When the outer ring 10 rotates, the recess 12 also rotates to deviate from the load range due to the in-cylinder pressure and the load range that receives the inertial force, and the damping effect by the oil film damper in the recess 12 cannot be exhibited properly. Since 2 is fitted in the fitting hole 31 of the cylinder block 3, the outer ring 10 does not rotate with respect to the cylinder block 3, and the concave portion 12 can be held in each load range.

  Next, the leakage flow rate at which the lubricating oil overflows from the gap S in the first and second embodiments will be described with reference to FIGS.

In the first embodiment shown in FIG. 5, the pressure of the lubricating oil filled in the gap S is P1 (Pascal), the atmospheric pressure is Pa (Pascal), the radius of the bearing hole 7 is D1 (meter), and the outer ring 10 (outer peripheral surface). If the radius of 11) is D2 (meters), the leakage flow rate U1 at which the lubricating oil leaks from both sides of the gap S is expressed by the following equation.
U1 = α / √ (1-m ² α ² ) · √ {2 [(P1-Pa) / ρ]} × 2

Here, m is an aperture ratio, but m = 1 because there is no aperture element in the gap S. Α is a contraction coefficient, and ρ is the density (Kg / m ³ ) of the lubricating oil. Therefore, the leakage flow rate U1 is
U1 = α / √ (1-α ² ) · √ {2 [(P1-Pa) / ρ]} × 2
It becomes.

In the second embodiment shown in FIG. 6, the pressure of the lubricating oil filled in the gap S is P2 (Pascal), the pressure of the lubricating oil in the place where the gap S is narrowed by the axial wall portion 12b is P1 (Pascal), When the atmospheric pressure is Pa (Pascal), the radius of the bearing hole 7 is D1 (meter), the radius of the outer ring 10 (outer peripheral surface 11) is D2 (meter), and the radius of the concave peripheral surface of the outer ring 10 is D3 (meter). The leakage flow rate U2 at which the lubricating oil leaks from both sides of the gap S is expressed by the following equation.
U2 = α / √ (1-m ² α ² ) · √ {2 [(P2-P1) / ρ]} × 2

Here, the aperture ratio m is
^{m = (D1 2 -D2 2)} / (D1 2 -D3 2) <1 Since,
α / √ (1-m ² α ² ) α <α / √ (1-α ² ).
Also, since Pa is atmospheric pressure,
P2-P1 <P1-Pa∵Pa << P1 <P2
Therefore, U2 <U1. That is, in the second embodiment, since the leakage flow rate of the lubricating oil is smaller than that in the first embodiment and the leakage is small, the hydraulic pressure can be kept high for a longer time, and it is possible to withstand a stronger load.

  According to the present invention, when the engine is started, the journal portion 6 is smoothly rotated and supported by the roller bearing 1 with smaller friction, and thereafter, the oil pump is driven so that the lubricating oil flows between the outer ring 10 of the roller bearing 1 and the bearing hole. The oil film damper is formed by being supplied to the gap S between the cylinder 7 and the cushion effect of absorbing the explosion load in the combustion stroke. Even during operation, an impact load such as explosion pressure can be absorbed by the damping effect by the oil filled in the gap S between the outer ring 10 of the roller bearing 1 and the bearing hole 7, and noise can be reduced.

  Further, since the outer ring 10 does not rotate with respect to the cylinder block 3 by the fixing pin 2, the viscous resistance of the oil film damper formed in the gap S can be ignored, and the journal portion 6 can roll the roller bearing 1. Friction is small and smoothly rotated by friction.

  Furthermore, since it is only necessary to form the bearing hole 7 for attaching the roller bearing 1 larger than the diameter of the outer ring 10 of the roller bearing 1, processing is easy and can be manufactured at low cost.

DESCRIPTION OF SYMBOLS 1 Roller bearing 2 Fixing pin 3 Cylinder block 4 Bearing cap 6 Journal part 7 Bearing hole 10 Outer ring 11 Outer surface 12 Recessed part 12a Circumferential wall part 12b Axial wall part 14 Inner peripheral surface 15 Track groove 16 Roller 17 Retainer 30 Oil passage 31 Mating hole S Clearance

Claims (1)

A crankshaft roller bearing that is mounted in a bearing hole formed by a cylinder block and a bearing cap and rotatably supports a journal portion of the crankshaft,
An outer ring fitted in the bearing hole with a gap therebetween,
A plurality of rollers arranged on the inner circumferential surface of the outer ring at intervals in the circumferential direction and in contact with the journal portion so as to be rotatable;
An oil passage formed in the cylinder block for supplying oil to the gap to form an oil film damper;
A recess formed by recessing the outer peripheral surface or the inner peripheral surface along the circumferential direction above and below the outer peripheral surface of the outer ring or the inner peripheral surface of the bearing hole,
A fixing pin interposed between the outer ring and the cylinder block or the bearing cap so that the outer ring cannot move in the circumferential direction and can move in the reciprocating direction of the piston;
The recess has a circumferential wall at both circumferential ends and an axial wall,
The crankshaft roller bearing is characterized in that the oil passage is formed in the cylinder block so as to supply the lubricating oil as it is to the recess above the recess .

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