JP2011052572A - Valve gear of internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a valve gear of an internal combustion engine having high levels of supply and injection performances of lubricating oil while securing sufficient rigidity and strength with a simple structure. <P>SOLUTION: A lubricating oil passage 1b is formed inside a rocker shaft 1 to supply lubricating oil to an outer cylinder surface 1a. A housing part 3 of a rocker arm 2 is freely rockably journaled to the outer cylinder surface 1a. The lower cylinder wall of the rocker shaft 1 in the housing part 3 is formed thicker than the upper cylinder wall. A first oil hole 4 is formed to penetrate the upper cylinder wall. An arm part 5 extending substantially horizontally from the housing part 3 is formed. The tip of the arm part 5 is brought into contact with a valve bridge 25. A pair of rib parts 6 is extended upward from both ends of the arm part 5 in an axial direction of the rocker shaft 1. A second oil hole 7 is formed to penetrate in proximity to a tip of the arm part 5. A bank part 9 is formed on the tip side from the second oil hole 7. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a valve operating mechanism that drives an intake valve and an exhaust valve of an internal combustion engine.

  In a valve operating mechanism (valve system) of an internal combustion engine, an intake valve and an exhaust valve are connected to a rocker arm pivotally supported by a rocker shaft, and each valve is opened and closed by swinging the rocker arm. Such a valve mechanism is provided with a mechanism for supplying lubricating oil to the frictional sliding surface of each member. Since the lubrication performance of the valve mechanism is an element that affects the performance of the internal combustion engine as a whole, various techniques for improving the lubrication performance have been proposed.

  For example, in Patent Document 1, an in-shaft oil passage through which lubricating oil flows is formed inside a rocker shaft (arm support shaft), and the lubricating oil is supplied to a valve head (valve cap) and a push rod via the rocker arm. Is described. In this technique, an oil guide groove is formed along the longitudinal direction of the upper surface of the rocker arm to secure a flow path for the lubricating oil supplied from the rocker shaft.

  Further, in Patent Document 2, in a lubrication device for a valve operating mechanism that supplies lubricating oil from a rocker shaft (valve arm shaft) to a rocker arm (valve arm), an oil passage and a lubricating oil reservoir are formed on the top of the rocker arm. In addition, there is described that a recess as a lubricating oil reservoir is formed on the upper surface of the valve bridge. In this technique, it is said that a stable amount of oil can be secured by temporarily storing the lubricating oil in the lubricating oil reservoir.

JP 2001-263031 A Japanese Patent No. 4038111

  However, the conventional technology as described above has a structure in which the lubricating oil is supplied by dripping from the tip of the rocker arm, so there is a possibility that the amount of oil supply and the oil supply location may vary, and there is a problem that reliable oil supply is not guaranteed. is there. In particular, as described in Patent Document 2, in the case of a valve mechanism having a structure in which the tip of the rocker arm and the vicinity of the center of the valve bridge are in contact with each other, the lubricating oil is more directed toward the rocker shaft than the tip of the rocker arm. Cannot supply.

  Further, in the techniques described in Patent Documents 1 and 2, since the flow path of the lubricating oil is formed on the upper surface of the rocker arm, the lubricating oil is supplied to this flow path from the internal oil passage inside the rocker shaft. There is also a problem that the distance in the vertical direction becomes longer. That is, as the distance between the upper surface of the rocker arm and the in-shaft oil passage increases, the pressure of the lubricating oil acting on the in-shaft oil passage increases, and the jetting performance decreases. As a result, depending on the operating state of the engine, there may be a case where the lubricating oil cannot be sufficiently supplied. On the other hand, if the thickness of the rocker arm in the vertical direction is reduced, the extension distance of the vertical oil passage can be shortened accordingly, but it is difficult to ensure the rigidity and strength of the rocker arm instead.

  The present invention has been made in view of such problems, and with a simple configuration, while ensuring sufficient rigidity and strength, it is possible to provide a high level of lubricating oil supply and jetting properties. An object is to provide a valve mechanism for an internal combustion engine.

  In order to achieve the above object, a valve operating mechanism for an internal combustion engine according to a first aspect of the present invention includes a rocker shaft that is fixed to a cylinder head and has a lubricating oil passage therein, and a rocker shaft that swings relative to an outer cylindrical surface of the rocker shaft. A rocker arm that is pivotally supported, a first member that contacts one end of the rocker arm and transmits rocking to the rocker arm (for example, a push rod), and another end of the rocker arm that contacts the rocker arm. In a valve operating mechanism of an internal combustion engine including a second member (for example, a valve bridge) that transmits to a valve, the rocker shaft supplies lubricating oil introduced through the lubricating oil passage to the outer cylinder surface. In addition, the rocker arm is formed in a hollow cylindrical shape having an inner cylindrical surface that is in sliding contact with the outer cylindrical surface of the rocker shaft, and a cylindrical wall below the rocker shaft is a cylinder above the rocker shaft. A thicker housing part, a first oil hole formed through the cylinder wall above the rocker shaft from the inner cylinder surface of the housing part, and substantially horizontally from the housing part An arm portion that extends in the radial direction of the rocker arm and contacts the second member, and along the extending direction of the arm portion, upward from both ends of the arm portion in the axial direction of the rocker shaft A pair of extending rib portions, a second oil hole penetrating in the vertical direction near the tip of the arm portion between the pair of rib portions, and the second oil between the pair of rib portions And a bank portion formed so as to protrude upward on the tip side from the hole.

  According to a second aspect of the present invention, there is provided a valve operating mechanism for an internal combustion engine according to the present invention, in addition to the structure of the first aspect, wherein the rocker arm is disposed on the opposite side of the arm portion across the inner cylindrical surface of the housing portion. There is an adjustment screw fixing portion that protrudes and contacts the first member, and the adjustment screw fixing portion is perforated through the inside of the adjustment screw fixing portion in the vertical direction, and has a screw groove in the hole wall. A screw hole, an adjustment screw that is screwed into the screw groove formed in the hole wall of the screw hole, and contacts the upper end of the first member, and the diameter of the hole wall is increased at the lower end of the screw hole. A recess processing portion having a recess cylindrical surface formed in the step, and a third oil hole formed through the recess processing portion from the recess cylindrical surface to the inner cylindrical surface of the housing portion. It is said.

  According to a third aspect of the present invention, there is provided a valve operating mechanism for an internal combustion engine according to the present invention, in addition to the structure of the first or second aspect, wherein the rocker shaft has an in-plane direction perpendicular to the axial direction of the rocker shaft on the outer cylinder surface. A first oil groove formed in an annular shape, a second oil groove formed in parallel to the axial direction of the rocker shaft on the outer cylindrical surface, and the lubricating oil passage inside the rocker shaft; And an internal oil passage connecting the intersection of the first oil groove and the second oil groove.

That is, the second oil groove is formed so as to intersect the first oil groove perpendicularly on the outer cylinder surface.
According to a fourth aspect of the present invention, there is provided a valve operating mechanism for an internal combustion engine according to the present invention, wherein the second oil groove is formed shorter than the width of the housing portion in the axial direction of the rocker shaft. In addition, in a plane perpendicular to the axial direction of the rocker shaft, the rocker shaft is provided at a position offset by a predetermined angle from the vertical lower side of the shaft with respect to the axis of the rocker shaft.

That is, the second oil groove is formed avoiding the lower end position of the rocker shaft where high surface pressure is generated between the outer cylindrical surface of the rocker shaft and the inner cylindrical surface of the rocker arm.
According to a fifth aspect of the present invention, there is provided a valve operating mechanism for an internal combustion engine according to the present invention, in addition to the configuration according to the fourth aspect, wherein the offset angle from the vertical lower side of the shaft in the second oil groove is the rocker shaft of the rocker arm. It is characterized in that it is set so as to be substantially equal to the swing angle with respect to.

  A valve operating mechanism for an internal combustion engine according to a sixth aspect of the present invention further includes a rocker cover that covers the rocker shaft and the upper surface of the rocker arm in addition to the structure according to any one of the first to fifth aspects. The rocker cover is provided with a lubricating oil catching surface for receiving the lubricating oil injected upward from the first oil hole of the rocker arm, and projecting downward from the inner surface of the rocker cover. It is characterized by having an embankment part which is arranged so as to surround the outer periphery of the catching surface and allows the lubricating oil on the lubricating oil catching surface to fall between the pair of rib parts.

According to a seventh aspect of the present invention, there is provided a valve operating mechanism for an internal combustion engine according to the present invention, in addition to the structure according to any one of the first to sixth aspects, wherein the housing portion is located at a central portion in the axial direction of the rocker shaft. The cylindrical wall has a thin wall portion and a pair of second rib portions formed thicker than the thin wall portion at both axial ends of the rocker shaft.
According to an eighth aspect of the present invention, there is provided a valve operating mechanism for an internal combustion engine according to the present invention, in addition to the configuration according to the seventh aspect, wherein the pair of rib portions are connected to the rocker shaft in the housing portion from both ends of the arm portion. It is characterized in that it extends upward and is located immediately above the pair of second rib portions.

According to the valve operating mechanism (Claim 1) of the internal combustion engine of the present invention, the lubricating oil injected from the first oil hole to the upper part of the housing portion is circulated between the pair of rib portions, and is passed through the second oil hole. The fuel can be supplied to the second member side and can be reliably supplied to the valve head.
Further, the wall thickness of the cylindrical wall of the housing part is formed thicker on the lower side than the upper side of the rocker shaft (that is, the shaft of the rocker shaft is eccentric with respect to the center of the outer peripheral surface of the housing part). Therefore, the weight can be reduced while suppressing deformation with respect to the load. Further, by adopting a bushless structure in which the inner cylindrical surface of the housing portion and the outer cylindrical surface of the rocker shaft are in sliding contact with each other, the number of parts can be reduced and the weight can be reduced, and the cost can be reduced.

Furthermore, the rigidity of the arm portion can be ensured by extending the pair of rib portions upward from both ends of the arm portion.
Further, by providing the bank portion, the lubricating oil flowing between the pair of rib portions can be easily guided to the second oil hole, and the oil supply property to one side of the second member can be improved. Moreover, the lubricating oil overflowing from the bank part can be dropped from the tip of the arm part and supplied to the other side of the second member. By changing the shape and height of the bank portion, the supply distribution to one side or the other side of the lubricating oil supplied to the second member can be changed.

Further, according to the valve operating mechanism of the internal combustion engine of the present invention (Claim 2), the lubricating oil supplied from the third oil hole is introduced into the recessed cylindrical surface whose diameter of the hole wall at the lower end of the screw hole is expanded. Therefore, the lubricating oil does not flow along the thread groove, and the lubricating oil can be directly supplied to the first member, so that reliable oil supply is possible.
Further, according to the valve operating mechanism of the internal combustion engine of the present invention (Claim 3), the lubricating oil supplied from the internal oil passage is supplied to the circumferential direction of the rocker shaft (that is, the direction of the first oil groove) and the axial direction (that is, the direction). Can be quickly distributed in the direction of the second oil groove). Thereby, not only can the lubricating oil be reliably supplied to the first oil hole and the third oil hole, but also the entire sliding contact surface between the rocker shaft and the rocker arm can be reliably lubricated.

Further, according to the valve operating mechanism for an internal combustion engine of the present invention (Claim 4), the second oil groove is formed while avoiding the vertical downward of the shaft of the rocker shaft where high surface pressure is generated, so that the sliding surface Wear resistance can be improved while ensuring lubricity.
Further, according to the valve mechanism of the internal combustion engine of the present invention (Claim 5), the lubricating oil supplied from the second oil groove to the inner cylindrical surface of the housing portion by the rocker arm swinging is supplied to the shaft of the rocker shaft. It can be reliably supplied vertically downward, and the lubricity and wear resistance of the sliding surface can be further improved.

Further, according to the valve operating mechanism for an internal combustion engine of the present invention (Claim 6), the rocker cover is provided with the lubricating oil catching surface and the bank portion, thereby preventing scattering of the lubricating oil injected above the rocker arm. Therefore, the loss of lubricating oil can be reduced.
Further, according to the valve operating mechanism for an internal combustion engine of the present invention (Claim 7), the central portion in the axial direction of the housing portion is formed thinner than both end portions thereof, thereby further reducing the weight while ensuring the rigidity of the housing portion. Can be achieved.

  In addition, according to the valve operating mechanism for an internal combustion engine of the present invention (Claim 8), the rib portion of the arm portion is positioned immediately above the second rib portion of the housing portion, thereby providing a stress-favorable cross-sectional shape. The strength and rigidity can be further increased.

It is sectional drawing which shows the whole structure of the valve operating mechanism of the internal combustion engine which concerns on one Embodiment of this invention. It is sectional drawing (BB sectional drawing of FIG. 4) of the rocker arm of this valve operating mechanism. FIG. 3 is a partial cross-sectional view of a rocker arm of the valve operating mechanism, where (a) is a cross-sectional view along A1-A1 in FIG. 2, (b) is a cross-sectional view along A2-A2 in FIG. 2, and (c) is a cross-sectional view along A3-A3 in FIG. FIG. It is a top view of the rocker arm of this valve operating mechanism. It is a typical perspective view which shows the rocker shaft of this valve operating mechanism. It is a typical perspective view which shows the rocker shaft in the valve mechanism as a modification of this invention.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[1. Constitution]
[1-1. Overview Configuration]
FIG. 1 illustrates an OHV (overhead valve) type multi-cylinder diesel engine (internal combustion engine) to which a valve operating mechanism 10 according to the present invention is applied. Here, the outline of the cylinder block 32 is indicated by a two-dot chain line. A cylinder head 30 is fixed on the cylinder block 32, and an intake port 39, an exhaust port, a water jacket, and the like connected to each cylinder are disposed therein. FIG. 1 is a cross-sectional view of one cylinder 38 of a plurality of cylinders arranged in the cylinder block 32 taken along a plane perpendicular to the rotation axis of the crankshaft.

A pair of intake valves 36 and exhaust valves (not shown) are provided above the cylinder 38, and the valve train 10 drives these valves to open and close. The device configuration for driving each of the intake valve 36 and the exhaust valve is substantially the same, and the details related to the intake valve 36 will be described in detail below.
FIG. 1 shows the valve operating mechanism 10 with the intake valve 36 closing the intake port 39. The vertical and horizontal directions in the following description are directions based on the arrangement position and orientation of each member described in FIG.

  The valve mechanism 10 includes a camshaft 35, a push rod 23 (first member), a rocker shaft 1, a rocker arm 2, a valve bridge 25 (second member), and a rocker cover 20. The rocker cover 20 is a member fixed so as to cover the upper part of the cylinder head 30, and forms a space for housing members such as the rocker shaft 1 and the rocker arm 2 therein.

The camshaft 35 is a shaft member disposed in the cylinder block 32. The camshaft 35 is connected to the crankshaft via a power transmission mechanism (not shown), and rotates around the rotation axis O at an angular velocity corresponding to the rotational movement of the crankshaft.
As shown in FIG. 1, an egg-shaped flat cam 34 having a fixed distance from the rotation axis O to the peripheral surface 34 a is fixed to the camshaft 35. The lower surface 33 a of the tappet 33 supported by the lower end portion of the push rod 23 is in contact with the peripheral surface 34 a of the flat cam 34. The push rod 23 is supported so as to be slidable in the vertical direction with respect to the cylinder head 30 and periodically reciprocates in the vertical direction according to the rotation angle of the camshaft 35. The upward pressing force applied to the push rod 23 by the rotational movement of the cam shaft 35 acts to rotate the rocker arm 2 in the right direction in FIG.

  The rocker shaft 1 is a shaft member fixed to the cylinder head 30 via a bracket 37, and pivotally supports the rocker arm 2 on its outer cylindrical surface 1a. The interior of the rocker shaft 1 is hollow, and the central axis of the hollow cylinder coincides with the central axis of the outer cylinder surface 1a. Hereinafter, these central axes are simply referred to as a cylinder axis C. The cylinder axis C is parallel to the rotation axis O of the camshaft 35 and extends in a direction perpendicular to the paper surface of FIG. The hollow cylinder inside the rocker shaft 1 functions as a flow path (lubricating oil path) 1b for lubricating oil supplied to various parts of the valve operating mechanism 10.

The rocker arm 2 includes a hollow cylindrical housing portion 3 that is pivotally supported by the rocker shaft 1, an arm portion 5 that extends in the left and right directions in FIG. 1 around the housing portion 3, and an adjustment screw fixing portion 8. It is prepared for. The housing part 3, the arm part 5 and the adjustment screw fixing part 8 are integrally formed of cast iron.
The arm part 5 of the rocker arm 2 is a part formed so as to extend from the housing part 3 in a direction substantially horizontal and perpendicular to the cylinder axis C (radial direction of the rocker shaft 1). The distal end portion 5a of the arm portion 5 is formed to have a greater thickness in the vertical direction than the base end portion side. The adjustment screw fixing portion 8 is a portion protruding from the side of the housing portion 3 opposite to the side on which the arm portion 5 extends.

An adjusting screw 12 is fastened and fixed to the adjusting screw fixing portion 8. A cup end 24 fitted into the upper end portion of the push rod 23 is in contact with the lower end portion of the adjustment screw 12. As a result, the rocker arm 2 swings around the rocker shaft 1 in accordance with the vertical reciprocation of the push rod 23.
The relative position between the adjusting screw 12 and the adjusting screw fixing portion 8 (that is, the contact position between the cup end 24 and the adjusting screw 12) can be changed, and thereby the rocking arm 2 swing start angle and end angle can be changed. Fine adjustment is possible. The rocking width of the rocker arm 2 (difference between the rocking start angle and end angle) depends on the distance from the rotation axis O of the flat plate cam 34 to the peripheral surface 34a.

On the other hand, the valve bridge 25 connected to the intake valve 36 is in contact with the lower end surface 5b of the distal end portion 5a of the arm portion 5, and the rocker arm 2 swinging is transmitted to the intake valve 36 through this. . This lower end surface 5b is formed as a smooth curved surface convex downward, and the surface is subjected to a curing process such as a chill process.
The valve bridge 25 is a rod-like member disposed substantially horizontally below the arm portion 5 and supports the intake valves 36 at both ends. The configuration of the pair of intake valves 36 is the same. As shown in FIG. 1, the upper surface 25 a of the central portion of the valve bridge 25 is formed to be smooth and is in contact with the lower end surface 5 b of the distal end portion 5 a of the arm portion 5. The relative position of the lower end surface 5b on the arm portion 5 side and the upper surface 25a on the valve bridge 25 side varies according to the rocking of the rocker arm 2. For example, when the valve bridge 25 is used as a reference, the lower end surface 5b is above the upper surface 25a. The valve bridge 25 slides back and forth in the extending direction. On the other hand, the width of the upper surface 25a in the extending direction of the valve bridge 25 is set to be larger than the width at which the lower end surface 5b slides back and forth.

  The intake valve 36 includes a valve stem 26, a spring seat 27, a valve spring 28, a stem guide 29, and a valve head 40. The valve head 40 is a valve body that opens and closes the intake port 39 with respect to the cylinder 38. The valve stem 26 is a shaft-like part formed integrally with the valve head 40 and is supported so as to be slidable with respect to the cylinder head 30 via a stem guide 29.

The stem guide 29 is a hollow cylindrical member that is fitted into the valve through hole 30a of the cylinder head 30 and supports the valve stem 26 therein. An oil seal 31 that seals the sliding contact surface between the stem guide 29 and the valve stem 26 is attached to the upper end portion of the stem guide 29.
In the vicinity of the upper end portion of the valve stem 26, spring receiving seats 27 that are in contact with both end portions of the valve bridge 25 are fixed. Further, a valve spring 28 for biasing the spring receiving seat 27 upward is interposed between the spring receiving seat 27 and the upper surface of the cylinder head 30. The urging force applied to the spring seat 27 by the valve spring 28 is transmitted to the rocker arm 2 via the valve bridge 25, and acts to rotate the rocker arm 2 in the left direction in FIG.

[1-2. Detailed configuration]
The configuration of the rocker arm 2 of the valve operating mechanism 10 will be described in detail.
As shown in FIG. 2, the housing portion 3 of the rocker arm 2 is formed with a cylindrical inner cylindrical surface 3 a that is in sliding contact with the outer cylindrical surface 1 a of the rocker shaft 1, and the rocker shaft 1 is inserted therethrough. The rocker arm 2 has a bushless structure, and the inner cylindrical surface 3a and the outer cylindrical surface 1a are in contact with each other.

The outer peripheral surface 18 of the housing part 3 forms a part of a cylindrical surface (indicated by a broken line in FIG. 2) with the cylindrical axis D as the center. On the other hand, the inner cylinder surface 3a of the housing part 3 is drilled so that the cylinder axis C is positioned slightly above the cylinder axis D vertically. The cylinder axis C and the cylinder axis D are parallel. That is, the inner cylindrical surface 3a is provided eccentrically upward with respect to the outer peripheral surface 18 of the housing part 3, and as shown in FIG. 2, the thickness t ₂ of the lower cylindrical wall in the housing part 3 is It is thicker than the thickness t ₁ of the upper cylindrical wall (t ₁ <t ₂ ).

  A first oil hole 4 penetrating to the inner cylindrical surface 3a is formed in the upper outer peripheral surface 18 (that is, the portion where the cylindrical wall is formed thin) in the housing portion 3. As shown in FIG. 2, the hole core F of the first oil hole 4 is inclined to the arm portion 5 side (valve bridge 25 side) with the cylinder axis C as a fulcrum in the vertical cross section of the cylinder axis C. The first oil hole 4 functions as a supply port for lubricating oil introduced from the rocker shaft 1.

  The arm part 5 of the rocker arm 2 extends from the outer peripheral surface 18 of the housing part 3 toward the valve bridge 25 side. A pair of rib portions 6 are erected upward from both ends of the arm portion 5 in the extending direction of the cylinder axis C. As shown in a side view in FIG. 2, the pair of rib portions 6 is formed with a streamlined outline not only on the arm portion 5 but also on the upper portion of the housing portion 3 and the upper portion of the adjustment screw fixing portion 8. ing.

  Hereinafter, the space surrounded by the arm portion 5 and the pair of rib portions 6 is referred to as a lubricating oil flow path 5c. The arm 5 is formed in a U-shaped cross section as shown in FIG. 3A in order to form a lubricating oil flow path 5c on its upper surface. Note that a space surrounded by the upper outer peripheral surface 18 and the pair of rib portions 6 in the housing portion 3 is also included in the lubricating oil flow path 5c. The pair of rib portions 6 are not connected by the tip portion 5a of the arm portion 5, that is, the flow path 5c is opened at the tip portion 5a.

  A second oil hole 7 penetrating the arm portion 5 in the vertical direction is formed on the flow path 5c closer to the base end portion than the distal end portion 5a. As shown in FIG. 2, the second oil hole 7 is provided on the upper surface 25 a of the valve bridge 25. Moreover, the upper end surface of the front-end | tip part 5a is formed so that it may protrude upwards. Hereinafter, the upper end surface of the front end portion 5a is referred to as a bank portion 9. The bank portion 9 functions to dam the lubricating oil flowing through the flow path 5 c and to secure the flow rate of the lubricating oil flowing into the second oil hole 7. The second oil hole 7 functions as a supply port for introducing lubricating oil to the valve bridge 25 side.

  Of the lubricating oil introduced into the valve bridge 25 through the flow path 5c, the lubricating oil flowing out from the second oil hole 7 is mainly supplied to the left intake valve 36 in FIG. Further, the lubricating oil flowing out from the opened front end portion 5a is mainly supplied to the right intake valve 36 side in FIG. The supply balance of these lubricating oils depends on the diameter of the second oil hole 7, the shape and height of the bank portion 9, and the like.

  The adjustment screw fixing portion 8 of the rocker arm 2 is a portion to which the adjustment screw 12 for changing the correspondence between the vertical sliding position of the push rod 23 and the rocking angle of the rocker arm 2 is fixed. A processing unit 13 is provided. The screw hole 11 is a hole drilled through the inside of the adjustment screw fixing portion 8 in the vertical direction. The hole wall of the screw hole 11 is engraved with a screw groove that is screwed into the adjustment screw 12.

On the upper end surface 8a of the adjustment screw fixing portion 8 in which the screw hole 11 is drilled, a spot facing process is applied to form a smooth surface. The upper end surface 8a is a surface to which a tightening nut of the adjustment screw 12 is fastened and fixed.
On the lower end side inside the screw hole 11, a recessed portion 13 formed by expanding the hole wall of the screw hole 11 is formed. The inner surface of the recess portion 13 has a smooth cylindrical shape, and no thread groove is formed. Hereinafter, the inner surface of the recess processing portion 13 is referred to as a recess cylinder surface 13a.

  A third oil hole 14 penetrating to the inner cylinder surface 3a of the housing portion 3 is formed in the recess cylinder surface 13a. The third oil hole 14 functions as a supply port for introducing lubricating oil to the push rod 23 side. As shown in FIG. 3 (b), the coupling portion between the housing portion 3 and the adjustment screw fixing portion 8 is formed in an H-shaped cross section, and the third oil hole 14 is formed in the rocker arm 2 in the extending direction of the cylinder shaft C. Located in the center of

In the present embodiment, as shown in FIG. 2, the third oil hole 14 is formed so as to penetrate from the left side surface of the adjustment screw fixing portion 8 to the inner cylindrical surface 3 a of the housing portion 3. What is necessary is just to connect between the part 13 and the inner cylinder surface 3a.
Further, as shown in FIG. 3C, a pair of second rib portions 19 are formed at both ends in the extending direction of the cylindrical shaft C on the lower side of the housing portion 3. These second rib portions 19 are portions that hang downward from the outer peripheral surface 18 on the lower side of the housing portion 3. The housing portion 3 has an H-shaped cross section except for the inside of the inner cylindrical surface 3a through which the rocker shaft 1 is inserted, and the thickness of the cylindrical wall at the center of the housing portion 3 in the extending direction of the cylindrical shaft C. Is t ₂ as described above. On the other hand, the thickness t ₃ of the cylindrical wall in the second rib portion 19 is formed to be thicker (t ₂ <t ₃ ) than the thickness t ₂ of the central cylindrical wall. In other words, the thickness t ₂ of the cylindrical wall of the outer peripheral surface 18 of the lower housing part 3 is thinner than the second rib portion 19, the outer peripheral surface 18 of the lower housing part 3 is formed as a thin portion .

A pair of rib portions 6 extending from the arm portion 5 side is provided on the upper side of the housing portion 3. The position of the pair of rib portions 6 in the extending direction of the cylinder axis C is directly above the pair of second rib portions 19.
A center line E passing through the center of the third oil hole 14 is shown in FIG. The outer shape of the rocker arm 2 in a top view is non-plane-symmetric with respect to the vertical plane passing through the center line E due to the restriction of the layout of the space in which the main valve mechanism 10 is installed. Here, although the center of the 1st oil hole 4, the 2nd oil hole 7, the 3rd oil hole 14, and the screw hole 11 is not located on the same straight line in the top view, these positions are arrange | positioned on the same straight line. May be. The distance between the center of the first oil hole 4 and the center line E is preferably small.

In addition, an embankment portion 22 projecting downward is formed above the rocker arm 2 on the inner surface of the rocker cover 20. In FIG. 4, the shape of the bank portion 22 is projected and indicated by a broken line.
The bank portion 22 is annularly disposed so as to surround the first oil hole 4 formed in the outer peripheral surface 18 of the housing portion 3 and the second oil hole 7 formed in the arm portion 5. The outline of the bank portion 22 is elliptical in plan view. Thereby, the lubricating oil sprayed upward from the first oil hole 4 is received by the ceiling surface 21 (lubricating oil capturing surface) of the rocker cover 20 surrounded by the bank portion 22, and between the pair of rib portions 6. Fall into.

Next, the rocker shaft 1 of the main valve mechanism 10 will be described in detail.
As shown in FIG. 5, a first oil groove 15 and a second oil groove 16 are formed on the outer cylindrical surface 1 a of the rocker shaft 1. The first oil groove 15 is a groove formed in an annular shape in a plane perpendicular to the cylinder axis C. The center point of the first oil groove 15 is indicated by a point G in FIG. The aforementioned rocker arm 2 is attached to the rocker shaft 1 so that the center line E in the top view is located on the first oil groove 15. Therefore, the first oil groove 15 is connected to the first oil hole 4 and the third oil hole 14 regardless of the rocking angle of the rocker arm 2.

The second oil groove 16 is a groove formed in parallel to the cylinder axis C, and is orthogonal (vertically intersects) with the first oil groove 15. As shown in FIG. 5, the width W ₂ of the second oil groove 16 in the extending direction of the cylinder axis C is a sliding surface where the outer cylindrical surface 1 a of the rocker shaft 1 and the inner cylindrical surface 3 a of the rocker arm 2 are in sliding contact. Shorter than the width W ₁ (W ₂ <W ₁ ). That is, in the state where the rocker arm 2 is attached to the rocker shaft 1, the second oil groove 16 is hidden inside the sliding contact surface, so that both end portions thereof do not protrude from the sliding contact surface.

  A straight line passing through the intersection of the first oil groove 15 and the second oil groove 16 and the point G in FIG. 5 is slightly inclined toward the valve bridge 25 with respect to the vertical line from the point G. The two oil grooves 16 are provided at positions offset from the vertically lower side of the cylinder axis C. The above inclination angle is set as θ and is shown in FIGS. 2 and 5. The magnitude of the inclination angle θ is set to be approximately the same as the swing angle of the rocker arm 2 with respect to the rocker shaft 1. The swing angle here means the swing width of the rocker arm 2 (difference between swing start angle and end angle). For example, the closed intake valve 36 opens the intake port 39 to the maximum. This is the angle at which the rocker arm 2 swings until it is done.

  In addition, an internal oil passage 17 that connects the lubricating oil passage 1 b to the intersection of the first oil groove 15 and the second oil groove 16 is formed inside the rocker shaft 1. The internal oil passage 17 is perforated in a direction perpendicular to the cylinder axis C, and connects the lubricating oil passage 1b and the intersections of the first oil groove 15 and the second oil groove 16 with the shortest distance. Through this internal oil passage 17, the lubricating oil flowing in the lubricating oil passage 1 b of the rocker shaft 1 is always supplied to both the first oil groove 15 and the second oil groove 16.

[2. Action, effect]
[2-1. Physical properties related to power transmission]
Actions and effects relating to power transmission in the valve train 10 will be described.
When the flat plate cam 34 pushes up the tappet 33 in accordance with the rotation of the camshaft 35, the push rod 23 pushes up the adjustment screw fixing portion 8 upward, and the rocker arm 2 swings in the right rotation direction in FIG. Since the rocker arm 2 swings in a circular motion around the rocker shaft 1, the lower end surface 5 b of the tip 5 a of the arm 5 rolls or slides on the upper surface 25 a of the valve bridge 25 while moving the valve bridge 25. Press down.

The pressing force input from the arm portion 5 to the valve bridge 25 is transmitted to the valve spring 28 via the spring receiving seat 27, the valve spring 28 is compressed and contracted, and the valve stem 26 is moved downward in the stem guide 29. Slide. Therefore, the valve head 40 is pushed into the cylinder 38 and the intake port 39 is opened.
On the other hand, since the intake valve 36 is urged upward by the valve spring 28, the tappet 33 and the push rod 23 move downward and the rocker arm 2 swings in the counterclockwise direction in FIG. At the same time, the valve bridge 25 and the valve stem 26 slide upward, and the valve head 40 closes the intake port 39.

During the swinging movement, the rocker arm 2 receives an upward pressing force from the adjusting screw fixing portion 8 when the intake valve 36 is opened, and the upward force is applied to the arm portion 5 when the intake valve 36 is closed. You will be under pressure. Therefore, a large surface pressure acts on the lower end portion of the outer cylindrical surface 1 a of the rocker shaft 1 and the lower end portion of the inner cylindrical surface 3 a of the rocker arm 2.
On the other hand, the rocker arm 2 of Hondoben mechanism 10, thicker than the thickness t ₁ of the thickness t ₂ is the upper side of the cylindrical wall of the lower side of the cylindrical wall than the rocker shaft 1 in the housing portion 3 (t ₁ <t ₂ Therefore, weight reduction can be achieved while suppressing deformation with respect to the load. Further, by adopting a bushless structure in which the inner cylindrical surface 3a of the housing portion 3 and the outer cylindrical surface 1a of the rocker shaft 1 are in sliding contact with each other, the number of parts can be reduced and the weight can be further reduced, and the cost can be reduced. Can do.

Further, as shown in FIG. 3C, a pair of second rib portions 19 are formed on the outer peripheral surface 18 on the lower side of the housing portion 3, and the cylindrical wall between these second rib portions 19 is the second rib. Since it is formed thinner (t ₂ <t ₃ ) than the thickness t ₃ of the cylindrical wall in the portion 19, the member can be reduced in weight while ensuring the required cross-sectional performance.
Further, as shown in FIG. 3A, since the cross section of the arm portion 5 of the rocker arm 2 is formed in a U-shaped cross section, the vertical member length (that is, the vertical length of the pair of rib portions 6). ) Can be improved in cross-sectional performance, and there is an advantage that the rigidity of the member can be easily secured. Further, there is an advantage that the flow path 5c can be easily secured between the pair of rib portions 6. Further, as shown in FIGS. 3B and 3C, in the housing portion 3, the rocker arm 2 has a H-shaped cross section, so that the rigidity can be further increased.

  As shown in FIG. 3C, each of the pair of rib portions 6 in the arm portion 5 is located immediately above the pair of second rib portions 19 in the housing portion 3, and therefore, these rib portions 6 , 19 can reliably transmit the stress in the vertical direction. In particular, as shown in FIGS. 2 and 3 (b), these rib portions 6 and 19 are arranged in the vertical direction at the proximal end portion of the arm portion 5 and the proximal end portion (housing portion 3 side) of the adjustment screw fixing portion 8. Since the connected cross section is formed, the cross section is advantageous in terms of stress, and the rigidity and strength of the rocker arm 2 can be further increased.

[2-2. Lubrication on the valve bridge side]
Lubricating oil of the valve operating mechanism 10 flows from the lubricating oil passage 1b formed inside the rocker shaft 1 through the internal oil passage 17 and is introduced into the first oil groove 15 and the second oil groove 16 on the outer cylindrical surface 1a. Is done. The lubricating oil introduced into the first oil groove 15 is supplied to the first oil hole 4 and the third oil hole 14.
The lubricating oil introduced into the first oil hole 4 via the first oil groove 15 flows out to the upper outer peripheral surface 18 side in the housing part 3, and passes through the flow path 5 c between the pair of rib parts 6 to reach the arm. It flows to the tip 5 a side of the part 5, passes through the inside of the second oil hole 7, and is supplied to the upper surface 25 a of the valve bridge 25. At this time, since the bank portion 9 is provided further to the tip side than the second oil hole 7, an appropriate amount of the lubricating oil flowing through the flow path 5c can be guided to the second oil hole 7, and the valve bridge It is possible to lubricate the upper surface 25a of 25 and the portions on the left intake valve 36 side in FIG.

  The remaining lubricating oil that has passed over the bank portion 9 is dropped from the tip portion 5 a of the arm portion 5 and supplied to the upper surface 25 a of the valve bridge 25. Accordingly, the upper surface 25a of the valve bridge 25 and the portions on the right intake valve 36 side in FIG. 1 can also be lubricated. By changing the height and shape of the bank portion 9, the ratio between the amount of lubricating oil supplied to the second oil hole 7 side and the amount of lubricating oil overflowing from the bank portion 9 and flowing out from the distal end portion 5 a of the arm portion 5 is changed. The supply distribution to one side or the other side of the lubricating oil supplied to the valve bridge 25 can be changed.

Further, in the present rocker arm 2, the inner cylindrical surface 3a of the housing portion 3 is provided eccentrically with respect to the outer peripheral surface 18, and the thickness t ₁ of the upper cylindrical wall is equal to the thickness t ₂ of the lower cylindrical wall. Compared to the thin wall. Thereby, compared with the structure without eccentricity, the length of the 1st oil hole 4 formed in the upper side of the housing part 3 can be shortened. That is, since the distance in the vertical direction of the first oil hole 4 is shortened, the injection property of the lubricating oil from the first oil hole 4 can be improved.

  In addition, since the embankment part 22 is provided above the rocker arm 2 on the inner surface of the rocker cover 20, the momentum of the lubricating oil to be injected is too large and the lubricating oil is sprayed on the rocker cover 20. Even so, the lubricating oil can be received by the ceiling surface 21 inside the bank portion 22 and dropped between the pair of rib portions 6. Therefore, the lubricating oil can be used effectively, and the supply loss of the lubricating oil can be reduced.

[2-3. Push rod side lubrication]
The lubricating oil introduced into the third oil hole 14 via the first oil groove 15 is introduced into the recess processing portion 13 in the adjustment screw fixing portion 8, and is passed through the recess cylindrical surface 13 a and the surface of the adjustment screw 12 to the cup end. 24 and the push rod 23. At this time, since the thread groove surface is not formed in the recess cylindrical surface 13a, the lubricating oil is easy to flow downward and good oil supply property is obtained. In particular, the lubricating oil transmitted through the surface of the adjusting screw 12 can be directly supplied to the contact portion between the lower end portion of the adjusting screw 12 and the cup end 24, and the oil can be reliably supplied to the push rod 23 side. it can.

[2-4. Lubrication of rocker arm sliding surface]
On the other hand, the lubricating oil introduced into the second oil groove 16 spreads in the extending direction of the cylinder shaft C and is supplied into the sliding contact surface between the outer cylindrical surface 1a of the rocker shaft 1 and the inner cylindrical surface 3a of the rocker arm 2. . At this time, since the internal oil passage 17 of the rocker shaft 1 is connected to the intersection of the first oil groove 15 and the second oil groove 16, the lubricating oil is quickly supplied to both the first oil groove 15 and the second oil groove 16. Be distributed to.

Since the second oil groove 16 is provided at an offset position avoiding a vertically downward portion of the outer cylindrical surface 1a that has a high surface pressure, the flowability of the lubricating oil is not hindered. Accordingly, the lubricating oil can be supplied stably, and the wear resistance can be improved while ensuring the lubricity of the sliding surface.
Further, since the inclination angle θ of the second oil groove 16 is set to be approximately the same as the swing angle of the rocker arm 2 with respect to the rocker shaft 1, the lubricating oil supplied from the second oil groove 16 is transferred to the rocker arm 2. As a result of the oscillation, the outer cylinder surface 1a is dragged to a vertically downward position, and the high surface pressure portion is reliably lubricated. Therefore, the lubricity and wear resistance of the sliding surface can be further improved.

[3. Others]
Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the spirit of the present invention.
In the above-described embodiment, the valve operating mechanism 10 that drives the intake valve 36 to open and close is illustrated, but the exhaust valve may be driven to open and close with the same configuration. In the above-described embodiment, the main valve mechanism 10 is applied to an OHV multi-cylinder diesel engine. However, the present embodiment may be applied to a single-cylinder gasoline engine or an OHC engine. May be.

  For example, a first member (for example, an overhead cam) having a function corresponding to the push rod 23 and the cup end 24 in the above-described embodiment, and a second member (for example, a valve stem 26) having a function corresponding to the valve bridge 25. The valve mechanism 10 of the present invention can be applied. In this case, the first member swings the rocker arm 2 pivotally supported by the rocker shaft 1, and the second member transmits the swing to the valve (for example, the valve head 40).

Even in such a configuration, as in the above-described embodiment, it is possible to provide a high level of lubricating oil supply and jetting properties while ensuring sufficient rigidity and strength.
Further, in the above-described embodiment, the rocker shaft 1 is illustrated with one second oil groove 16 provided therein. However, as shown in FIG. 6, for example, two may be provided. In this case, the second oil groove 16a similar to that of the above-described embodiment is provided at the position of the inclination angle θ from the vertically lower side of the cylinder axis C, and parallel to the second oil groove 16a at the position of the inclination angle −θ. And the 3rd oil groove 16b of the same width is provided. In this case, an internal oil passage 17a connecting the lubricating oil passage 1b to the intersection of the first oil groove 15 and the second oil groove 16a is formed, and the first oil groove 15 and the third oil groove 16b are connected from the lubricating oil passage 1b. It is preferable to form an internal oil passage 17b that connects up to the intersection.

  With such a configuration, the lubricity in the sliding contact surface between the outer cylindrical surface 1a of the rocker shaft 1 and the inner cylindrical surface 3a of the rocker arm 2 can be further improved.

DESCRIPTION OF SYMBOLS 1 Rocker shaft 1a Outer cylinder surface 1b Lubricating oil path 2 Rocker arm 3 Housing part 3a Inner cylinder surface 4 First oil hole 5 Arm part 5a Front end part 5b Lower end surface 5c Channel 6 Pair of rib part 7 Second oil hole 8 Adjustment screw Fixed portion 8a Upper end surface 9 Bank portion 10 Valve mechanism 11 Screw hole 12 Adjust screw 13 Recessed portion 13a Recess cylindrical surface 14 Third oil hole 15 First oil groove 16 Second oil groove 17 Internal oil passage 18 Outer peripheral surface 19 First Two ribs 20 Rocker cover 21 Ceiling surface (lubricating oil capturing surface)
22 Embankment 23 Push rod (first member)
24 Cup end 25 Valve bridge (second member)
25a Upper surface 26 Valve stem 27 Spring seat 28 Valve spring 29 Stem guide 30 Cylinder head 30a Valve through hole 31 Oil seal 32 Cylinder block 33 Tappet 33a Lower surface 34 Flat plate cam 34a Circumferential surface 35 Camshaft 36 Intake valve (valve)
37 Bracket 38 Cylinder 39 Intake port 40 Valve head

Claims (8)

A rocker shaft fixed to the cylinder head and having a lubricating oil passage inside;
A rocker arm that is pivotally supported with respect to the outer cylindrical surface of the rocker shaft;
A first member that contacts one end of the rocker arm and transmits a swing to the rocker arm;
In a valve operating mechanism for an internal combustion engine comprising a second member that contacts the other end of the rocker arm and transmits the swing to the valve,
The rocker shaft supplies lubricating oil introduced through the lubricating oil passage to the outer cylindrical surface,
The rocker arm
The rocker shaft has an inner cylindrical surface that is in sliding contact with the outer cylindrical surface, and is formed in a hollow cylindrical shape. The cylindrical wall below the rocker shaft is formed thicker than the cylindrical wall above the rocker shaft. A housing part;
A first oil hole formed through the cylindrical wall above the rocker shaft from the inner cylindrical surface of the housing portion;
An arm portion that extends substantially horizontally from the housing portion in the radial direction of the rocker arm and contacts the second member;
A pair of rib portions extending upward from both ends of the arm portion in the axial direction of the rocker shaft along the extending direction of the arm portion,
A second oil hole penetrating in the vertical direction in the vicinity of the tip of the arm between the pair of ribs;
A valve operating mechanism for an internal combustion engine, comprising: a bank portion formed so as to protrude upward on the tip end side of the second oil hole between the pair of rib portions. The rocker arm has an adjustment screw fixing portion that protrudes on the opposite side of the arm portion across the inner cylindrical surface of the housing portion and contacts the first member;
The adjustment screw fixing part is
A screw hole which is drilled through the inside of the adjustment screw fixing portion in the vertical direction and has a screw groove on the hole wall;
An adjustment screw that is screwed into the screw groove formed in the hole wall of the screw hole and contacts the upper end of the first member;
A recess processing portion having a recess cylindrical surface formed by expanding the hole wall at the lower end of the screw hole;
The valve operating mechanism for an internal combustion engine according to claim 1, further comprising a third oil hole formed so as to penetrate from the recess cylindrical surface of the recess processing portion to the inner cylindrical surface of the housing portion. . The rocker shaft
A first oil groove formed in an annular shape in a plane perpendicular to the axial direction of the rocker shaft on the outer cylindrical surface;
A second oil groove formed in parallel to the axial direction of the rocker shaft on the outer cylindrical surface;
3. The internal combustion engine according to claim 1, further comprising: an internal oil passage that connects the lubricating oil passage inside the rocker shaft and an intersection of the first oil groove and the second oil groove. Valve mechanism. The second oil groove is formed shorter than the width of the housing portion in the axial direction of the rocker shaft, and the shaft is centered on the axis of the rocker shaft in a plane perpendicular to the axial direction of the rocker shaft. The valve operating mechanism for an internal combustion engine according to claim 3, wherein the valve operating mechanism is provided at a position offset by a predetermined angle from a vertically lower side of the internal combustion engine. 5. The internal combustion engine according to claim 4, wherein an offset angle of the shaft in the second oil groove from a vertically lower side is set to be substantially equal to a swing angle of the rocker arm with respect to the rocker shaft. Valve mechanism. A rocker cover that covers the rocker shaft and the upper surface of the rocker arm;
The rocker cover has a lubricating oil catching surface for receiving the lubricating oil sprayed upward from the first oil hole of the rocker arm;
The rocker cover protrudes downward from the inner surface, is disposed around the outer periphery of the lubricating oil capturing surface, and drops the lubricating oil on the lubricating oil capturing surface between the pair of rib portions. The valve mechanism for an internal combustion engine according to any one of claims 1 to 5, further comprising a bank portion. The housing part is
In the central portion of the rocker shaft in the axial direction, a thin wall portion with a thin cylindrical wall;
It has a pair of 2nd rib part formed more thickly than this thin part in the both ends of the axial direction of this rocker shaft, The any one of Claims 1-6 characterized by the above-mentioned. A valve mechanism for an internal combustion engine. The pair of rib portions are extended from the both end sides of the arm portion to above the rocker shaft in the housing portion, and are positioned directly above the pair of second rib portions, The valve mechanism for an internal combustion engine according to claim 7.

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