JP2009215939A - Valve stem end lubricating structure - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a valve stem end lubricating structure improving a lubricating condition of a valve stem end driven by a rocker arm. <P>SOLUTION: The valve stem end lubricating structure for an engine 1 is provided with: a valve 110 including a stem 112 projecting out upward from a valve element 111; a camshaft 130 having a cam surface 131 driving the valve formed thereon; the rocker arm 140 provided in such a manner that the same can rock around a rotary shaft 141 and including a cam abutment part 143 abutting on the cam surface 131 and a valve abutment part 144a abutting on a stem upper end part 113 of the valve; a rocker cover 160 provided above the rocker arm; and oil galleries 161, 162, 163 formed in the rocker cover and supplying lubricating oil to a position higher than the valve abutment part of an upper surface part of the rocker arm. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an engine valve shaft end lubrication structure for driving a valve using a rocker arm.

The OHC engine drives a valve that opens and closes an intake port and an exhaust port by a camshaft provided in a cylinder head. Such an OHC engine generally transmits a driving force from the camshaft to the valve by using a rocker arm that swings around an axis arranged in parallel with the camshaft.
The valve drive mechanism as described above generally supplies lubricating oil to the camshaft from an oil pump provided in the crankcase portion via an oil gallery formed in the cylinder portion, cylinder head portion, etc. In many cases, the lubricating oil is splashed by the generated centrifugal force to be lubricated.

Further, in Patent Document 1, in the OHC engine, the sliding contact portion between the rocker arm and the cam and the sliding contact portion with the intake / exhaust valve of the rocker arm can be lubricated without increasing the amount of lubricating oil circulated. For this purpose, an oil supply passage for supplying lubricating oil from above the cam shaft to the sliding contact portion between the cam and the rocker arm, and an oil groove for guiding the lubricating oil to the sliding contact portion with the head of the valve may be formed. Are listed. In the engine of Patent Document 1, since the valve head is provided below the camshaft, the lubricant that lubricates the cam uses its own weight and oil groove to slide the rocker arm and the valve head. Can lead to.
JP-A-8-28235

  However, in the case of the OHC engine in which the valve shaft end is provided above the camshaft, it is difficult to guide the lubricating oil to the sliding contact portion between the rocker arm and the valve shaft end in the same manner as the engine of Patent Document 1. Therefore, conventionally, the lubrication of the sliding contact portion between the rocker arm and the valve shaft end in such an engine has adopted a method in which the splash of lubricating oil is scattered by the centrifugal force generated by the rotation of the camshaft immersed in the oil reservoir. In the case of this method, there is no problem when the engine speed is high to some extent in the case of the lubrication method in which the lubricating oil splash is scattered by the centrifugal force due to the rotation of the camshaft, but the centrifugal force is insufficient at low speeds such as idling. As a result, the amount of lubricating oil scattered may be insufficient. There is no problem when idling is a short time. However, a good lubrication state cannot be obtained under a usage condition in which an engine mounted on a vehicle such as an ATV is idling for a long time instead of a generator. In some cases, wear of the valve shaft end due to insufficient lubrication may be a problem.

  An object of the present invention is to provide a valve shaft end lubrication structure that improves the lubrication state of a valve shaft end driven by a rocker arm.

The present invention solves the above-described problems by the following means.
According to the first aspect of the present invention, there is provided a valve having a stem protruding upward from a valve body that opens and closes an intake port or an exhaust port of an engine, a camshaft having a cam surface that drives the valve, and a swing around a rotation axis. A cam abutting portion that abuts on the cam surface of the camshaft and a valve abutting portion that abuts on the stem upper end of the valve, and transmits a driving force from the camshaft to the valve. A rocker arm, a rocker cover provided above the rocker arm, and an oil gallery that is formed on the rocker cover and supplies lubricating oil to a position higher than the valve contact portion on the upper surface of the rocker arm. It is a shaft end lubrication structure.

According to a second aspect of the present invention, the upper surface portion of the rocker arm is formed to extend from immediately below the outlet of the oil gallery to the vicinity of the valve contact portion, and the lubricating oil that has come out of the oil gallery is on the valve contact portion side. The valve shaft end lubricating structure according to claim 1, further comprising a guide portion for guiding the valve shaft.
According to a third aspect of the present invention, the oil gallery has a main gallery to which the lubricating oil is supplied and a sub gallery that is branched from the main gallery and connected to an outlet for supplying the lubricating oil to the rocker arm. The sub gallery includes a small diameter portion provided in the vicinity of a connection portion with the main gallery, and a large diameter portion provided in a range other than the small diameter portion and having an inner diameter larger than the small diameter portion. The valve shaft end lubrication structure according to claim 1 or claim 2.

According to the present invention, the following effects can be obtained.
(1) By supplying the lubricating oil from the oil gallery to a position higher than the valve abutting portion on the upper surface portion of the rocker arm, the lubricating oil flows to the valve abutting portion along the upper surface portion of the rocker arm by its own weight, and the valve shaft end To be supplied. As a result, it is possible to prevent the valve shaft end from running out of lubricating oil, improve the lubrication state, and suppress wear.
(2) By providing, on the upper surface of the rocker arm, a guide portion that extends from directly under the oil gallery outlet to the vicinity of the valve contact portion, the lubricating oil supplied from the oil gallery is reliably supplied to the valve shaft end. be able to.
(3) Small-diameter drilling for forming a small-diameter portion by forming the sub-gallery with a small-diameter portion provided in the vicinity of the connecting portion with the main gallery and a large-diameter portion provided in a range other than the small-diameter portion. However, the required range can be reduced, the process can be simplified, the tool life can be extended, and the productivity can be improved.

  An object of the present invention is to provide a valve shaft end lubrication structure that improves the lubrication state of a valve shaft end driven by a rocker arm. An oil gallery is formed inside a rocker cover that supports a rocker shaft that is a rocker shaft of the rocker arm. Then, the lubricating oil is dropped from the oil gallery onto the guide rib on the upper surface of the rocker arm, and the lubricating oil flows along the guide rib to the valve shaft end.

Hereinafter, an embodiment of an engine to which the valve shaft end lubrication structure of the present invention is applied will be described.
The engine of the embodiment is, for example, a 4-stroke single-cylinder water-cooled OHC engine mounted on an ATV.
FIG. 1 is a cross-sectional view of an engine viewed along a plane orthogonal to the axial direction of the crankshaft and including the central axis of the cylinder.
2 is a cross-sectional view taken along the line II-II in FIG.
The engine 1 includes a crankshaft 10, a piston 20, a connecting rod 30, a crankcase 40, a cylinder 50, a throttle body 60, a cam chain 70, a cylinder head 100, and the like.

The crankshaft 10 is an output shaft of the engine 1, and is formed with a crankpin 11 to which a connecting rod 30 is connected, a cam drive sprocket 12 (see FIG. 2), and the like. The center axis of the crankshaft 10 is arranged along the front-rear direction in a vehicle-mounted state.
The piston 20 is a member that is inserted into the bore of the cylinder 50 and reciprocates upon receiving combustion pressure.
The connecting rod 30 is a connecting member having a small end portion into which the piston pin of the piston 20 is inserted and a large end portion connected to the crank pin 11 of the crankshaft 10.

The crankcase 40 is a part that accommodates and supports the crankshaft 10.
The cylinder 50 is provided so as to protrude from the upper part of the crankcase 40, and a cylindrical liner into which the piston 20 is inserted is cast.
The throttle body 60 includes a throttle valve that adjusts the amount of air introduced into the intake port 102 of the cylinder head 100. The throttle body 60 is connected to the inlet side of the intake port 102 via an intake pipe.
The cam chain 70 is provided between the sprocket 12 of the crankshaft 10 and the sprocket 132 of the camshaft 130, and transmits a driving force from the crankshaft 10 to the camshaft 130.

The cylinder head 100 is provided in the upper part of the cylinder 50. The cylinder head 100 is of OHC type and has 4 valves per cylinder.
FIG. 3 is a cross-sectional view of the cylinder head 100 taken along a plane orthogonal to the rotation axis of the crankshaft 10.
FIG. 4 is an external view of the cylinder head 100 as viewed from above along the central axis direction of the cylinder 50.
FIG. 5 is an external perspective view of the cylinder head 100 as viewed obliquely from the rear and obliquely upward.
The cylinder head 100 includes a combustion chamber 101, an intake port 102, an exhaust port 103, an intake valve 110, an exhaust valve 120, a camshaft 130, an intake rocker arm 140, an exhaust rocker arm 150, a rocker cover 160, a head cover 170, and the like. ing. (The head cover 170 is not shown in FIGS. 3 to 5)

The combustion chamber 101 is a pent roof type combustion chamber provided in the lower part of the cylinder head 100 so as to face the inside of the cylinder 50.
The intake port 102 is a flow path for introducing fresh air supplied from the throttle body 60 into the combustion chamber 101.
The exhaust port 103 is a flow path for discharging the burned gas that has exited from the combustion chamber 101 to an exhaust pipe (not shown).

The intake valve 110 and the exhaust valve 120 include valve bodies 111 and 121 and stems 112 and 122, respectively.
The valve bodies 111 and 121 are portions that contact the valve seats of the intake port 102 and the exhaust port 103 to open and close the intake port 102 and the exhaust port 103.
The stems 112 and 122 are shaft-like portions formed by protruding upward from the valve bodies 111 and 121, respectively.
The intake valve 110 and the exhaust valve 120 open and close each port by reciprocating the stems 112 and 122 so as to be slidable in the axial direction with respect to the stem guide formed in the cylinder head 100. Two intake valves 110 and two exhaust valves 120 are provided side by side in the central axis direction of the crankshaft 10.

The intake valve 110 and the exhaust valve 120 include shaft end portions 113 and 123 and valve springs 114 and 124, respectively.
The shaft end portions 113 and 123 are upper end portions of the stems 112 and 122, and are portions pressed by the valve contact portion 144a of the intake rocker arm 140 and the valve contact portion 154a of the exhaust rocker arm 150, respectively.
The valve springs 114 and 124 are compression coil springs provided between the cylinder head 100 and a spring seat fitted in the shaft end portions 113 and 123, and stems 112 and 122 inserted concentrically on the inner diameter side. The valve springs 114 and 124 urge the intake valve 110 and the exhaust valve 120 toward the closed position.
A predetermined valve clamping angle is provided between the intake valve 110 and the exhaust valve 120, and the stems 112 and 122 of the valves are disposed so as to be inclined with respect to each other so that the shaft end portions 113 and 123 side are opened. .

The camshaft 130 is a rotating shaft on which a cam surface 131 that drives the intake valve 110 and the exhaust valve 120 is formed. The camshaft 130 is arranged with its central axis parallel to the crankshaft 10 and is sandwiched between the stems 112 and 122 of the intake valve 110 and the exhaust valve 120. Further, as shown in FIG. 1, the camshaft 130 is provided at a position lower than the shaft end portion 113 of the intake valve 110.
The camshaft 130 is provided with a sprocket 132 (see FIG. 2) to which a driving force is transmitted from the cam chain 70, and is driven by this to rotate at half the rotational speed of the crankshaft 10.
In addition, lubricating oil is pumped from the oil pump to the camshaft 130 via an oil gallery provided in the cylinder 50 and the like. Lubricating oil is also supplied from the cam surface 131 to the sliding portion between the intake rocker arm 140 and the exhaust rocker arm 150 via an oil gallery formed inside the camshaft 130.
Further, lubricating oil is supplied to an oil reservoir 180 provided in the cylinder head 100. The camshaft 130 sprays the lubricating oil in the oil reservoir 180 by rotating.

The intake rocker arm 140 and the exhaust rocker arm 150 are members that transmit the displacement of the cam surface 131 of the camshaft 130 to the shaft end portions 113 and 123 of the intake valve 110 and the exhaust valve 120, respectively.
The intake rocker arm 140 and the exhaust rocker arm 150 are swingably supported with respect to the intake rocker shaft 141 and the exhaust rocker shaft 151 mounted on the rocker cover 160, respectively. The intake rocker shaft 141 and the exhaust rocker shaft 151 are provided in parallel with the camshaft 130, and obliquely above the camshaft 130 (the intake rocker shaft 141 is on the intake port 102 side and the exhaust rocker shaft 151 is on the exhaust port 103 side). Has been placed.

As shown in FIG. 3, the intake rocker arm 140 and the exhaust rocker arm 150 include cylindrical portions 142 and 152, cam-side arms 143 and 153, and valve-side arms 144 and 154 that are integrally formed.
The cylindrical portions 142 and 152 are substantially cylindrical portions into which the intake rocker shaft 141 and the exhaust rocker shaft 151 are inserted on the inner diameter side. The intake rocker arm 140 and the exhaust rocker arm 150 swing when the outer peripheral surfaces of the intake rocker shaft 141 and the exhaust rocker shaft 151 slide with the inner peripheral surfaces of the cylindrical portions 142 and 152.
The cam side arms 143 and 153 are formed so as to protrude from the outer peripheral surfaces of the cylindrical portions 142 and 152 to the cam shaft 130 side, respectively. A cam contact portion that slides with the cam surface of the camshaft 130 is formed at the tip of the cam side arms 143 and 153.

The valve side arms 144 and 154 are formed to protrude from the outer peripheral surfaces of the cylindrical portions 142 and 152 to the shaft end portion 113 of the intake valve 110 and the shaft end portion 123 side of the exhaust valve 120, respectively. Valve contact portions 144a and 154a for pressing the shaft end portions 113 and 123 and adjusting nuts 144b and 154b for adjusting the valve clearance are provided at the tip ends of the valve side arms 144 and 154, respectively.
Since the engine of this embodiment is a four-valve engine having two intake valves 110 and two exhaust valves 120, two valve-side arms 144 and 154 are provided in each of the cylindrical portions 142 and 152, respectively. It has been.

Further, the valve side arms 144 and 154 are provided with ribs 145 and 155 that protrude from the upper surface portion and extend from the cylindrical portions 142 and 152 to the vicinity of the adjusting nuts 144b and 154b. As shown in FIG. 1, the upper surface of the rib 145 is formed and arranged as an inclined surface that is higher on the intake rocker shaft 141 side and lower on the shaft end 113 side.
These ribs 145 and 155 exhibit a reinforcing effect that improves the rigidity of the valve-side arms 144 and 154, and the intake-side ribs 145 allow the lubricating oil supplied from the oil gallery 161 of the rocker cover 160 to be supplied to the intake valve. It also functions as a guide for guiding to the shaft end 113 of 110. This point will be described in detail later.

The rocker cover (cam support) 160 is fixed to the cylinder head 100 and is provided so as to cover the upper portions of the main parts of the camshaft 130, the intake rocker arm 140 and the exhaust rocker arm 150. The rocker cover 160 is formed, for example, by subjecting a cast product made of an aluminum alloy to predetermined machining.
The rocker cover 160 has a side surface rising from the upper surface of the cylinder head 100 and an upper surface formed continuously with the upper end of the side surface. An intake rocker shaft 141 and an exhaust rocker shaft 151 are inserted into a side surface portion of the rocker cover 160 and are rotatably disposed. The upper surface portion of the rocker cover 160 covers the cylindrical portions 142 and 152 and the cam side arms 143 and 153 of the intake rocker arm 140 and the exhaust rocker arm 150. The upper surface portion is formed in a flat plate shape arranged along a plane substantially orthogonal to the axial direction of the cylinder 50.
The rocker cover 160 also functions as a cam support member that supports the upper portion of the camshaft 130.

An oil gallery 161 for supplying lubricating oil to the upper surface of the valve side arm 144 of the intake rocker arm 140 is formed on the upper surface portion of the rocker cover 160. The oil gallery 161 includes a main gallery 162 and a sub gallery 163 formed inside the rocker cover 160.
The main gallery 162 is an oil passage that is disposed in the center of the upper surface of the rocker cover 160 and extends in parallel with the camshaft 130 and the rocker shafts 141 and 151. The main gallery 162 is supplied with lubricating oil pressurized by an oil pump from an oil gallery that lubricates the camshaft 130.

  The sub gallery 163 is an oil passage formed by branching from the main gallery 162 in a direction orthogonal to the main gallery 162 (that is, a direction parallel to the intake rocker arm 140). The sub gallery 163 is arranged substantially along the vehicle width direction of the engine 1 in the vehicle-mounted state. The sub gallery 163 has one end communicating with the main gallery 162 and the other end opening on the rear end side of the upper surface of the rocker cover 160. As shown in FIG. 5, the opening end of the sub gallery 163 is arranged on the upper side of the rib 145 of the intake rocker arm 140 and adjacent to the rib 145. In the present embodiment, a rib 181 extending downward is provided at the opening end of the sub gallery 163.

Further, the sub gallery 163 has an inner diameter in the vicinity of a connection portion with the main gallery 162, for example, about 2 mm (this portion is referred to as a small diameter portion). On the other hand, the inner diameter of the other part is set to, for example, about 4 mm, which is larger than the inner diameter in the vicinity of the connection part with the main gallery 162 (this part is referred to as a large diameter part). The small diameter portion of the sub gallery 163 functions as an orifice that adjusts the amount of lubricating oil flowing through the sub gallery 163.
At the time of manufacturing the rocker cover 160, the sub-gallery 163 first forms the large diameter portion with a cast pin, and then changes the tool to a small diameter drill to form the small diameter portion.

The head cover 170 is provided on the top of the cylinder head 100. The head cover 170 covers each component of the cylinder head 100 such as the valves 110 and 120, the camshaft 130, the rocker arms 140 and 150, and the rocker cover 160, and is an outer cover that is exposed to the outside of the engine 1. It is.
In the engine 1 of this embodiment, when the ATV is mounted on the vehicle body, the central axis of the cylinder 50 is disposed, for example, approximately 20 degrees forward for convenience of vehicle body design. As a result, the shaft end portion 113 of the intake valve 110 is disposed at a higher position than the camshaft 130, and lubrication by splashing from the camshaft 130 is difficult particularly during low-speed operation.

Next, the lubrication of the shaft end portion 113 of the intake valve 110 in the engine 1 will be described.
For example, when the rotational speed of the engine 1 is relatively low, such as during idling, the sub-gallery 163 of the rocker cover 160 is moved from the sub-gallery 163 of the rocker cover 160 to the upper part of the valve side arm 144 of the intake rocker arm 140 as shown by an arrow in FIG. Lubricating oil is dropped on the formed rib 145. The lubricating oil dropped on the rib 145 flows on the upper surface of the rib 145 by its own weight, and is supplied to the shaft end portion 113 of the intake valve 110 via the valve contact portion 144a of the valve side arm 144. It should be noted that the amount of lubricating oil dropped at this time is set to such an extent that wear due to running out of lubricating oil at the shaft end 113 can be prevented when the engine 1 is idling.
On the other hand, when the rotational speed of the engine 1 is relatively high, for example, when the vehicle is traveling, the shaft end portion 113 of the intake valve 110 is ejected from the sub gallery 163 due to the improved discharge pressure of the oil pump. And the lubricating oil splashes scattered by the camshaft 130.
The rib 181 guides dripping of lubricating oil from the opening end of the sub gallery 163 to the rib 145 of the valve side arm 144.

According to the embodiment described above, the following effects can be obtained.
(1) By supplying the lubricating oil from the sub gallery 163 of the oil gallery 160 to a position higher than the valve abutting portion 144a on the upper surface portion of the valve side arm 144 of the intake rocker arm 140, the lubricating oil is caused by its own weight. 144 and the rib 145 to flow to the valve contact portion 144a and are supplied to the shaft end portion 113 of the intake valve 110 to improve the lubrication state, and the wear of the shaft end portion 113 can be suppressed. Thereby, compared with the case where an oil jet is added etc., it can lubricate with a simple structure, for example.
(2) By providing a rib 145 formed on the upper surface of the intake rocker arm 140 so as to extend from directly under the outlet of the sub gallery 163 to the vicinity of the valve contact portion 144a, the lubricating oil supplied from the oil gallery 161 can be reliably provided. It can be guided to the shaft end 113 of the intake valve 110.
(3) The sub gallery 163 has a small diameter part provided in the vicinity of the connection part with the main gallery 162 and a large diameter part provided in a range other than the small diameter part, thereby forming a small diameter part. The range that requires drilling can be reduced, the process can be simplified, the tool life can be extended, and the productivity can be improved.

(Modification)
The present invention is not limited to the embodiments described above, and various modifications and changes are possible, and these are also within the technical scope of the present invention.
(1) In the above-described embodiment, since the lubrication condition of the intake valve shaft end is severe, the valve shaft end lubrication structure of the present invention is applied only to the intake valve side. Or may be provided only on the exhaust valve side.
(2) The engine of the embodiment is, for example, an SOHC type in which the intake and exhaust valves are driven by a single camshaft. However, the present invention is not limited to this, and the intake and exhaust valves are driven by independent camshafts. Even in the case of the DOHC type to be used, it can be applied as long as it uses a rocker arm instead of a direct push type.
(3) The shape, structure, arrangement and the like of each member constituting the valve shaft end lubrication structure are not limited to those of the above-described embodiments, and can be changed as appropriate. For example, in the embodiment, the guide portion that guides the lubricating oil from the oil gallery to the valve contact portion side is a rib. However, the guide portion is not limited thereto, and may be a groove, for example.

It is sectional drawing of the Example of the engine to which the valve-shaft end lubrication structure of this invention is applied. It is the II-II part arrow sectional drawing of FIG. It is sectional drawing of the cylinder head of the engine of FIG. FIG. 4 is an external view of the cylinder head of FIG. 3 viewed from the upper side in the cylinder central axis direction. It is the external appearance perspective view which looked at the cylinder head of Drawing 3 from the slanting back side and slanting upper side.

Explanation of symbols

1 Engine 10 Crankshaft 11 Crankpin 12 Sprocket 20 Piston 30 Connecting rod 40 Crankcase 50 Cylinder 60 Throttle body 70 Cam chain 100 Cylinder head 101 Combustion chamber 102 Intake port 103 Exhaust port 110 Intake valve 111 Valve body 112 Stem 113 Shaft end 114 Valve spring 120 Exhaust valve 121 Valve body 122 Stem 123 Shaft end 124 Valve spring 130 Cam shaft 131 Cam surface 132 Sprocket 140 Intake rocker arm 141 Intake rocker shaft 142 Cylindrical part 143 Cam side arm 144 Valve side arm 144a Valve contact part 144b Adjusting nut 145 Rib 150 Exhaust rocker arm 151 Exhaust rocker shaft 15 Tubular portion 153 cam arm 154 valve side arm 154a valve abutting portion 154b Adjusting nut 155 rib 160 rocker cover 161 oil gallery 162 main gallery 163 sub gallery 170 cover 180 Oil reservoir 181 rib

Claims (3)

A valve having a stem protruding upward from a valve body that opens and closes an intake port or an exhaust port of the engine;
A camshaft formed with a cam surface for driving the valve;
A cam abutting portion that abuts on the cam surface of the camshaft and a valve abutting portion that abuts on a stem upper end portion of the valve; A rocker arm that transmits driving force to
A rocker cover provided above the rocker arm;
A valve shaft end lubrication structure comprising: an oil gallery that is formed on the rocker cover and supplies lubricating oil to a position higher than the valve contact portion on the upper surface portion of the rocker arm. An upper surface portion of the rocker arm has a guide portion that extends from immediately below the outlet of the oil gallery to the vicinity of the valve contact portion and guides the lubricating oil that has come out of the oil gallery to the valve contact portion side. The valve shaft end lubrication structure according to claim 1, wherein: The oil gallery has a main gallery to which the lubricating oil is supplied and a sub gallery connected to an outlet for supplying the lubricating oil to the rocker arm that is branched from the main gallery.
The sub gallery has a small diameter portion provided in the vicinity of the connection portion with the main gallery, and a large diameter portion provided in a range other than the small diameter portion and having an inner diameter larger than the small diameter portion. The valve shaft end lubricating structure according to claim 1 or 2.

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