JP2014114913A - Rocker arm bearing - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a rocker arm bearing which can improve lubrication performance between an outer ring and a cam.SOLUTION: A rocker arm bearing 2 arranged at a dynamic valve mechanism 1 of an engine and assembled to a rocker arm 11 for opening and closing a valve 10 by the rotation of the cam 12 comprises: a support shaft 20 fixed to the rocker arm 11; the outer ring 21 which is arranged at an external periphery of the support shaft 20 and in which an external peripheral face 21a slides with the cam 12; and a plurality of rolling bodies 22 interposed between the outer ring 21 and the support shaft 20. A plurality of dynamic pressure generation oil grooves 3 are formed at the external peripheral face 21a of the outer ring 21 along the slide direction of the cam 12 which opposes the outer ring 21. Each dynamic pressure generation oil groove 3 includes a V-shaped part 3a at which a first groove 31 and a second groove 32 formed inclined to a reverse direction to each other with respect to the slide direction intersecting at a downstream end of the slide direction, and generates the fluid dynamic pressure of lubricant L at the downstream end of the V-shaped part 3a.

Description

  The present invention relates to a rocker arm bearing provided in a valve mechanism of an engine and incorporated in a rocker arm that opens and closes a valve.

  Conventionally, a rocker arm bearing described in Patent Document 1 is known as a rocker arm bearing provided in a valve operating mechanism of an engine that is a driving source of a vehicle and incorporated in a rocker arm that opens and closes a valve for intake or exhaust of a cylinder. ing.

  An engine valve mechanism described in Patent Document 1 includes a valve provided in a cylinder of an engine, a cam that rotates in synchronization with the movement of a piston in the cylinder, and swings by the rotation of the cam to press the valve. And a rocker arm bearing supported by the rocker arm, and a rocker arm that is in contact with one end of the rocker arm.

  The rocker arm has a support portion supported by the lash adjuster at one end in the longitudinal direction, and a pressing portion that presses the valve at the other end. A pair of through holes through which the shaft ends of the support shafts of the rocker arm bearings are inserted are formed in the central portion in the longitudinal direction of the rocker arm. The bearing for the rocker arm includes a support shaft supported by the pair of through holes of the rocker arm, a plurality of rolling elements disposed on the outer periphery of the support shaft, and an outer ring disposed on the outer peripheral side of the support shaft via the plurality of rolling elements. And is configured. The valve is urged by a coil spring in the valve closing direction (the direction toward the pressing portion of the rocker arm). The outer surface of the outer ring of the rocker arm bearing is pressed against the cam by receiving the biasing force of the coil spring through the rocker arm.

JP 2006-144848 A

  The rocker arm bearing configured as described above causes the rocker arm to swing with the rotation of the cam when the outer ring is pressed by the cam. When the cam rotates, the outer ring rotates relative to the support shaft by rolling of the plurality of rolling elements, and slip occurs between the outer peripheral surface of the cam and the outer peripheral surface of the outer ring. Since the lubricating oil of the engine is supplied to the outer peripheral surface of the cam and the outer peripheral surface of the outer ring, even if slippage occurs, the frictional resistance and wear are suppressed by the lubricating oil. As a result, the frictional resistance increases, and wear may be accelerated. This increase in frictional resistance affects the fuel consumption of the vehicle, and when the cam or outer ring wears, there is a problem that the lift amount of the valve becomes small and the engine output decreases.

  Therefore, an object of the present invention is to provide a rocker arm bearing capable of improving the lubricity between the outer ring and the cam.

  In order to achieve the above object, the present invention provides the following rocker arm bearings (1) to (7).

(1) A rocker arm bearing provided in a valve operating mechanism of an engine and incorporated in a rocker arm that opens and closes a valve by rotation of a cam, and is disposed on an outer periphery of the support shaft fixed to the rocker arm. An outer ring whose outer peripheral surface slides with the cam, and a plurality of rolling elements interposed between the outer ring and the support shaft, and the outer ring has a sliding direction of the cam with respect to the outer ring. A plurality of dynamic pressure generating oil grooves are formed along the groove, and the dynamic pressure generating oil grooves have a pair of grooves formed to be inclined in opposite directions with respect to the sliding direction. A rocker arm bearing that includes a V-shaped portion that intersects at an end portion and generates fluid dynamic pressure of lubricating oil at the downstream end portion of the V-shaped portion.

(2) The rocker arm bearing according to (1), wherein an angle formed by the pair of grooves is 10 ° to 90 °.

(3) The rocker arm bearing according to (1) or (2), wherein a groove width of the pair of groove portions is 30 nm to 150 nm.

(4) The rocker arm bearing according to any one of (1) to (3), wherein a groove depth of the pair of groove portions is 100 nm to 250 nm.

(5) The rocker arm according to any one of (1) to (4), wherein the plurality of dynamic pressure generating oil grooves are formed in parallel along the sliding direction at intervals of 0.5 μm to 100 μm. bearing.

(6) Oil guide grooves are formed on the outer peripheral surface of the outer ring so as to be inclined with respect to the sliding direction and guide lubricating oil between the plurality of dynamic pressure generating oil grooves. A rocker arm bearing according to any one of the above.

(7) The rocker arm bearing according to any one of (1) to (6), wherein a contact surface of the outer peripheral surface of the outer ring with the outer peripheral surface of the cam is mirror-finished.

  According to the present invention, the lubricity between the outer ring and the cam can be improved.

Schematic which shows the structural example of the valve operating mechanism of the engine provided with the bearing for rocker arms which concerns on embodiment of this invention. The side view which looked at the bearing and cam for rocker arms from the axial direction. Explanatory drawing which shows the shape of the oil groove formed in the outer peripheral surface of an outer ring | wheel. The principal part enlarged view which shows the peripheral part of the V-shaped part of several dynamic-pressure generation | occurrence | production oil grooves. (A) is a graph which shows the pressure (dynamic pressure) of the lubricating oil in the outer peripheral surface of an outer ring | wheel. (B) is sectional drawing of the outer ring | wheel in the cut surface parallel to the sliding direction containing the top part of several dynamic-pressure generation | occurrence | production oil grooves.

[Embodiment]
A first embodiment of the present invention will be described with reference to FIGS.

  FIG. 1 is a schematic view showing a configuration example of a valve mechanism for an engine provided with a rocker arm bearing according to an embodiment of the present invention. This rocker arm bearing is provided in a valve operating mechanism of an engine, and is incorporated in a rocker arm that opens and closes a valve by rotation of a cam.

  The valve operating mechanism 1 is for operating a valve 10 provided in a cylinder (not shown) in an engine that is an internal combustion engine, and includes a rocker arm 11 and a cam 12 that rotates in synchronization with the movement of a piston in the cylinder. The lash adjuster 13 for adjusting the valve clearance and the rocker arm bearing 2 are provided.

  The valve 10 has a valve head portion 101 that contacts the valve seat of the cylinder, and a shaft portion 102 that is integrally connected to the valve head portion 101. The valve 10 is biased toward the rocker arm 11 side by a coil spring (not shown).

  The rocker arm 11 includes a pair of opposed side walls 111, a pressing portion 112 formed at one end portion in the longitudinal direction of the pair of opposed side walls 111, and a support portion 113 formed at the other end portion in the longitudinal direction of the pair of opposed side walls 111. And have. The pressing portion 112 connects the pair of opposing side walls 111 and abuts on the end surface of the shaft portion 102 of the valve 10, and operates the valve 10 by swinging the rocker arm 11. The support portion 113 connects the pair of opposed side walls 111 and is supported by the lash adjuster 13 to be a swing center of the opposed side wall 111. The lash adjuster 13 suppresses the occurrence of valve clearance in the valve operating mechanism 1 using the hydraulic pressure of the lubricating oil of the engine.

  The pair of opposed side walls 111 is formed with a through hole 111a into which the shaft end portion of the support shaft 20 of the rocker arm bearing 2 is fitted. The support shaft 20 is fixed to the pair of opposing side walls 111 by caulking, for example, and the axial movement and rotation with respect to the rocker arm 11 are restricted.

  The cam 12 is provided on the camshaft 120 and rotates together with a timing gear driven by a timing chain wound around a gear connected to the crankshaft of the engine. The cam 12 has an outer peripheral surface 12 a that contacts the rocker arm bearing 2, and has a protruding portion 12 b that protrudes in one radial direction, and the protruding portion 12 b is used for the rocker arm as the camshaft 120 rotates. The bearing 2 is pressed to rock the rocker arm 11, and the valve 10 is moved in the valve opening direction against the biasing force of the coil spring.

  FIG. 2 is a side view of the rocker arm bearing 2 and the cam 12 as seen from the axial direction thereof. The rocker arm bearing 2 includes a support shaft 20 fixed to the rocker arm 11, an outer ring 21 disposed on the outer periphery of the support shaft 20, and an outer peripheral surface 21a sliding (moving relatively while rubbing) with the cam 12. A plurality of rolling elements 22 interposed between the outer ring 21 and the support shaft 20 are provided. In the present embodiment, the rocker arm bearing 2 is configured as a full roller bearing that does not have a cage, but may further include a cage that rotatably holds the plurality of rolling elements 22.

  The plurality of rolling elements 22 are cylindrical rollers, and roll with the outer peripheral surface 20a of the support shaft 20 and the inner peripheral surface 21b of the outer ring 21 as raceways. The outer ring 21 and the plurality of rolling elements 22 are disposed between the pair of opposed side walls 111 of the rocker arm 11, and axial movement is restricted by the pair of opposed side walls 111.

  The cam 12 is formed with an oil passage 121 for supplying lubricating oil to the outer peripheral surface 12a. The outer peripheral surface 12 a of the cam 12 and the outer peripheral surface 21 a of the outer ring 21 are lubricated by the lubricating oil supplied from the oil passage 121. The cam 12 does not need to be formed with the oil passage 121. In this case, the outer peripheral surface 12a of the cam 12 and the outer peripheral surface 21a of the outer ring 21 are lubricated by the lubricating oil present in a mist form in the accommodation space of the valve mechanism 1 in the engine or by the lubricating oil dropped from above.

  In the present embodiment, a plurality of oil grooves for improving the lubricity between the outer ring 21 and the cam 12 are formed on the outer peripheral surface 21 a of the outer ring 21. Next, the oil groove will be described in detail.

  FIG. 3 is an explanatory view showing the shape of oil grooves (dynamic pressure generating oil grooves 3, first oil guide grooves 41, and second oil guide grooves 42 described later) formed on the outer peripheral surface 21 a of the outer ring 21. In this figure, for the sake of explanation, a part of the oil grooves provided in the circumferential direction of the outer peripheral surface 21a of the outer ring 21 are extracted and developed on a plane, and the groove width is enlarged. It is shown.

  When the cam 12 rotates, the outer ring 21 rotates with respect to the support shaft 20 by the frictional force between the outer peripheral surface 12a of the cam 12 and the outer peripheral surface 21a of the outer ring 21, and the outer peripheral surface 12a of the cam 12 and the outer peripheral surface 21a of the outer ring 21. And the cam 12 slides on the outer peripheral surface 21 a of the outer ring 21. In the following description, the direction in which the cam 12 slides with respect to the outer ring 21 is referred to as “sliding direction”. Further, when the contact position of the cam 12 on the outer peripheral surface 21a of the outer ring 21 moves from the first position to the second position along this sliding direction, the first position side with respect to the second position is defined as “upstream in the sliding direction. The side of the second position relative to the first position is referred to as “downstream side in the sliding direction”. In FIG. 3, this sliding direction is indicated by an arrow A. In FIG. 3, the right side of the drawing corresponds to the upstream side in the sliding direction, and the left side of the drawing corresponds to the downstream side in the sliding direction.

  A plurality of dynamic pressure generating oil grooves 3, a plurality of first oil guide grooves 41, and a plurality of second oil guide grooves 42 are formed on the outer peripheral surface 21 a of the outer ring 21. The outer ring 21 is made of, for example, a steel material such as SUJ material (high carbon chrome bearing steel), and the plurality of dynamic pressure generating oil grooves 3, the plurality of first oil guiding grooves 41, and the plurality of second oil guiding grooves 42 are, for example, It is formed by laser processing.

  The dynamic pressure generating oil groove 3 has a first groove part 31 and a second groove part 32 which are formed to be inclined in opposite directions with respect to the sliding direction and form a pair. The first groove portion 31 and the second groove portion 32 are each formed in a straight line shape. The first groove portion 31 is inclined from one side surface 21c in the width direction of the outer ring 21 toward the other side surface 21d in the sliding direction, and the second groove portion 32 is one side from the other side surface 21d of the outer ring 21 in the sliding direction. It inclines toward the side surface 21c.

  A pair of 1st groove part 31 and 2nd groove part 32 comprise the V-shaped part 3a which cross | intersects in the top part 30 of the downstream edge part in a sliding direction. That is, the dynamic pressure generating oil groove 3 includes a V-shaped portion 3 a including a pair of first groove portions 31 and second groove portions 32. In the present embodiment, the dynamic pressure generating oil groove 3 is formed in a W shape in which two V-shaped portions 3 a are connected in the width direction of the outer ring 21.

Angle alpha (smaller angle (inferior angle of the first between the center line L ₃₁ of the groove 31 and the second groove 32 centerline L ₃₂ and the angle between the first groove 31 and second groove portion 32 is formed )) Is preferably 10 ° to 90 °. When the angle α is less than 10 °, the number of the dynamic pressure generating oil grooves 3 that can be formed on the outer peripheral surface 21a of the outer ring 21 is reduced, and the overall lubricity improvement effect by the plurality of dynamic pressure generating oil grooves 3 is improved. Will be limited. In addition, when the angle α exceeds 90 °, the ratio of the lubricating oil introduced into the first groove portion 31 and the second groove portion 32 flowing out from the portion other than the top portion 30 increases, and the fluid dynamic pressure described later decreases. End up. A more desirable range of the angle α is 30 ° to 60 °. In the present embodiment, the angle α is set to 45 ° as the most desirable value of the angle α.

  The first oil guide groove 41 is formed at the end portion on the side surface 21c side of the outer peripheral surface 21a of the outer ring 21, and is inclined in the same direction as the first groove portion 31 with respect to the sliding direction. The first oil guide groove 41 is formed in a straight line, and the downstream end 41b in the sliding direction is located closer to the center in the width direction of the outer ring 21 than the upstream end 41a. Further, the downstream end portion 41b of the first oil guiding groove 41 is located between two adjacent dynamic pressure generating oil grooves 3 (first groove portions 31) along the sliding direction.

  The second oil guiding groove 42 is formed at the end of the outer peripheral surface 21a of the outer ring 21 on the other side surface 21d side, and is inclined in the same direction as the second groove portion 32 with respect to the sliding direction. The second oil guide groove 42 is formed in a straight line, and the downstream end 42b in the sliding direction is located closer to the center in the width direction of the outer ring 21 than the upstream end 42a. Further, the downstream end portion 42b of the second oil guide groove 42 is positioned between two dynamic pressure generating oil grooves 3 (second groove portions 32) adjacent to each other along the sliding direction.

An angle β formed by the first oil guide groove 41 and the second oil guide groove 42 (an angle formed by an extension line L ₄₁ of the center line of the first oil guide groove ₄₁ and an extension line L ₄₂ of the center line of the second groove portion 32. Of these, the smaller angle (recess angle)) is preferably equal to or larger than the angle α. When the angle β is equal to or larger than the angle α, the lubricating oil can be guided between the adjacent dynamic pressure generating oil grooves 3 with a relatively short flow path length. Further, the lubricating oil that has flowed out from the downstream end portions 41b, 42b of the first oil guiding groove 41 and the second oil guiding groove 42 along the extension lines L ₄₁ , L ₄₂ of the center line is directly applied to the first groove portion. 31 and the second groove 32. The angle difference γ (angle difference γ = angle β−angle α), which is the difference between the angle β and the angle α, is preferably 10 ° to 20 °. In the present embodiment, the angle difference γ is set to 15 ° (angle β = 60 °).

  FIG. 4 is an enlarged view of a main part showing the periphery of the V-shaped part 3 a of the plurality of dynamic pressure generating oil grooves 3. Note that, as described above, in FIG. 3, some of the dynamic pressure generating oil grooves 3 out of the large number of dynamic pressure generating oil grooves 3 are illustrated for illustration, but FIG. 4 illustrates the enlarged view. All the dynamic pressure generating oil grooves 3 in the range are shown.

The plurality of dynamic pressure generating oil grooves 3 are formed in parallel along the sliding direction. The first groove portion 31 and the second groove portion 32 in each dynamic pressure generating oil groove 3 are parallel to each other. The groove width W of the first groove portion 31 and the second groove portion 32 is desirably 30 nm to 150 nm. When the groove width W is less than 30 nm, the amount of lubricating oil flowing through the first groove part 31 and the second groove part 32 is small, and the fluid dynamic pressure is limited. When the groove width W exceeds 150 nm, the effect of causing the lubricating oil in the first groove portion 31 and the second groove portion 32 to flow along the center lines L ₃₁ and L _{32 due} to the sliding of the cam 12 is poor. The dynamic pressure cannot be increased. A more desirable range of the groove width W is 50 nm to 100 nm. In the present embodiment, the groove width W is set to 70 nm.

  In FIG. 4, the interval I (sliding direction interval) between adjacent dynamic pressure generating oil grooves 3 is preferably 0.5 μm to 100 μm. When the distance I is less than 0.5 μm, the contact surface 21e on the outer peripheral surface 21a of the outer ring 21 (the cam in which the dynamic pressure generating oil groove 3, the first oil guide groove 41, and the second oil guide groove 42 are not formed) Since the contact surface pressure of the cam 12 is increased, wear is likely to occur. If the interval I exceeds 100 μm, the number of dynamic pressure generating oil grooves 3 that can be formed on the outer peripheral surface 21a of the outer ring 21 is reduced, and the effect of improving the overall lubricity by the plurality of dynamic pressure generating oil grooves 3 is limited. End up. A more desirable range of the interval I is 1 μm to 10 μm. In the present embodiment, the interval I is set to 1 μm.

  The contact surface 21e that contacts the cam 12 is mirror-finished by polishing. The surface roughness Ra of the contact surface 21e is desirably 10 nm or less.

  FIG. 5A is a graph showing the pressure (dynamic pressure) of the lubricating oil L on the outer peripheral surface 21 a of the outer ring 21. FIG. 5B is a cross-sectional view of the outer ring 21 on a cut surface parallel to the sliding direction including the top portions 30 of the plurality of dynamic pressure generating oil grooves 3. The horizontal axis of the graph of FIG. 5A corresponds to the position in the sliding direction of the outer ring 21 in the cross-sectional view of FIG.

  As shown in FIG. 5B, the dynamic pressure generating oil groove 3 has a rectangular cross-sectional shape, and the groove depth D is larger than the groove width W. The groove depth D is desirably 100 nm to 250 nm. Further, the groove width W is desirably 30 to 50% of the groove depth D. A more desirable range of the groove depth D is 150 to 200 nm. In the present embodiment, the groove depth D is set to 175 nm as the most desirable value of the groove depth D.

  The lubricating oil L on the outer peripheral surface 21 a of the outer ring 21 flows along the sliding direction by sliding with the outer peripheral surface 12 a of the cam 12. The lubricating oil L in the first oil guiding groove 41 and the second oil guiding groove 42 is dragged by the viscosity of the lubricating oil L flowing on the outer peripheral surface 12 a of the cam 12, and the first oil guiding groove 41 and the second oil guiding groove 42. To flow along. The first oil guide groove 41 and the second oil guide groove 42 collect the lubricating oil L on the center side in the width direction of the outer ring 21 as indicated by arrows in FIG. 31 and the second groove 32). The lubricating oil L in the first groove portion 31 and the second groove portion 32 flows toward the top portion 30 of the V-shaped portion 3a as shown by an arrow in FIG. 3, and the top portion 30 as shown in FIG. 5 (b). And ejected from the dynamic pressure generating oil groove 3.

  As shown in FIG. 5A, the pressure of the lubricating oil L increases on the downstream side of the top portion 30 in the sliding direction. As a result, the lubricating oil L is supplied between the outer peripheral surface 21 a of the outer ring 21 and the outer peripheral surface 12 a of the cam 12. The pressure of the lubricating oil L at the top 30 increases as the engine speed increases and the sliding speed of the cam 12 with respect to the outer ring 21 increases. That is, the pressure of the lubricating oil L generated by the dynamic pressure generating oil groove 3 is increased in a high engine speed range where the outer ring 21 and the cam 12 are likely to be worn (for example, a rotational speed of 4000 rpm or more). While suppressing wear of the outer ring 21 and the cam 12, an increase in frictional resistance can be suppressed.

  In the low engine speed range, the oil on the outer peripheral surface 21 a of the outer ring 21 is oozed out by the seepage of the lubricating oil L held in the dynamic pressure generating oil groove 3, the first oil guiding groove 41, and the second oil guiding groove 42. Cutting is suppressed. Thereby, generation | occurrence | production of abrasion and the increase in frictional resistance are suppressed.

(Operation and effect of the embodiment)
According to the present embodiment described above, the lubricating oil L can be supplied between the outer peripheral surface 21 a of the outer ring 21 and the outer peripheral surface 12 a of the cam 12 by the dynamic pressure generated in the dynamic pressure generating oil groove 3. In addition, it is possible to suppress wear of the outer ring 21 and the cam 12 and to suppress an increase in frictional resistance.

  In the present embodiment, the angle α formed by the first groove portion 31 and the second groove portion 32 is 10 ° to 90 °, and the groove width W of the first groove portion 31 and the second groove portion 32 is 30 nm to 30 nm. 150 nm, and the groove depth D of the first groove portion 31 and the second groove portion 32 is 100 nm to 250 nm. Therefore, when the rocker arm bearing 2 is incorporated in the rocker arm 11 and applied to the valve operating mechanism 1 of the engine, In particular, the lubricating oil L can be appropriately supplied by the dynamic pressure generated in the dynamic pressure generating oil groove 3 in a high engine speed range where the outer ring 21 and the cam 12 are likely to run out of oil. That is, the numerical value ranges of the angle α, the groove width W, and the groove depth D are configured such that the outer ring 21 that is rotatably supported by the plurality of rolling elements 22 with respect to the support shaft 20 slides with the cam 12. The valve operating mechanism 1 is designed so that the lubricating oil L is appropriately supplied. By setting the dimensions and angles of the respective parts as described above, the outer ring 21 and the engine It is possible to suppress the occurrence of wear and the increase in frictional resistance due to the sliding of the cam 12.

  In this embodiment, since the interval I between the dynamic pressure generating oil grooves 3 is 0.5 μm to 100 μm, the contact surface pressure of the cam 12 is excessive while ensuring the number of the dynamic pressure generating oil grooves 3. It becomes possible to introduce the appropriate amount of lubricating oil L into the dynamic pressure generating oil groove 3.

  Further, since the contact surface 21e of the outer ring 21 with the cam 12 is mirror-finished, the lubricating oil L ejected from the top 30 of the dynamic pressure generating oil groove 3 is the outer peripheral surface 21a of the outer ring 21 and the outer peripheral surface 12a of the cam 12. It can interpose appropriately between.

[Other embodiments]
Although the rocker arm bearing of the present invention has been described based on the embodiment, the present invention is not limited to this embodiment, and can be implemented in various modes without departing from the scope of the present invention. It is.

  For example, in the above-described embodiment, the case where the dynamic pressure generating oil groove 3 is formed in a W shape having two V-shaped portions 3a has been described. However, the present invention is not limited thereto, and one V-shaped portion 3a is formed. It may be V-shaped. Moreover, the dynamic pressure generating oil groove 3 may have three or more V-shaped portions 3a. Furthermore, a plurality of dynamic pressure generating oil grooves 3 may be arranged in the width direction of the outer ring 21.

  Moreover, although the said embodiment demonstrated the case where the 1st groove part 31 and the 2nd groove part 32 were formed in linear form, it is not restricted to this, The 1st groove part 31 and the 2nd groove part 32 are curved. You may do it. In this case, the angle α in the vicinity of the top portion 30 of the first groove portion 31 and the second groove portion 32 may be in the above range. In addition to the first groove portion 31 and the second groove portion 32, the dynamic pressure generating oil groove 3 may have, for example, a groove portion that is parallel to the sliding direction.

DESCRIPTION OF SYMBOLS 1 ... Valve mechanism, 2 ... Rocker arm bearing, 3 ... Dynamic pressure generating oil groove, 3a ... V-shaped part, 10 ... Valve, 11 ... Rocker arm, 12 ... Cam, 12b ... Projection part, 12a ... Outer peripheral surface, 13 Lash adjuster, 20 ... support shaft, 20a ... outer peripheral surface, 21 ... outer ring, 21a ... outer peripheral surface, 21b ... inner peripheral surface, 21c, 21d ... side surface, 21e ... contact surface, 22 ... rolling element, 30 ... top, 31 ... 1st groove part, 32 ... 2nd groove part, 41 ... 1st oil guide groove, 42 ... 2nd oil guide groove, 41a, 42a ... End part of upstream side, 41b, 42b ... End part of downstream side DESCRIPTION OF SYMBOLS 101 ... Valve part, 102 ... Shaft part, 111 ... Opposite side wall, 111a ... Through-hole, 112 ... Pressing part, 113 ... Support part, 120 ... Cam shaft, 121 ... Oil path, I ... Space, L ... Lubricating oil , L ₃₁ , L ₃₂ ... center line, L ₄₁ , L ₄₂ ... extension of the center line

Claims (7)

A rocker arm bearing provided in a valve mechanism of an engine and incorporated in a rocker arm that opens and closes a valve by rotation of a cam,
A support shaft fixed to the rocker arm;
An outer ring disposed on the outer periphery of the support shaft and having an outer peripheral surface that slides on the cam;
A plurality of rolling elements interposed between the outer ring and the support shaft;
On the outer peripheral surface of the outer ring, a plurality of dynamic pressure generating oil grooves are formed along the sliding direction of the cam with respect to the outer ring,
The dynamic pressure generating oil groove includes a V-shaped portion in which a pair of grooves formed to be inclined in opposite directions with respect to the sliding direction intersect at a downstream end portion in the sliding direction, A bearing for a rocker arm that generates fluid dynamic pressure of lubricating oil at the downstream end of the shaped portion. The angle formed by the pair of grooves is 10 ° to 90 °.
The rocker arm bearing according to claim 1. The groove width of the pair of groove portions is 30 nm to 150 nm.
The rocker arm bearing according to claim 1 or 2. The groove depth of the pair of groove portions is 100 nm to 250 nm.
The rocker arm bearing according to any one of claims 1 to 3. The plurality of dynamic pressure generating oil grooves are formed in parallel along the sliding direction at intervals of 0.5 μm to 100 μm.
The bearing for rocker arms according to any one of claims 1 to 4. An oil guide groove that is inclined with respect to the sliding direction and guides lubricating oil between the plurality of dynamic pressure generating oil grooves is formed on the outer peripheral surface of the outer ring.
The bearing for rocker arms according to any one of claims 1 to 5. The contact surface with the outer peripheral surface of the cam on the outer peripheral surface of the outer ring is mirror-finished,
The rocker arm bearing according to any one of claims 1 to 6.

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