JP2010281295A - Valve gear of internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To inhibit the generation of uneven wear between a cam face and a crest face and between a head and a valve seat while obtaining the free rotation of a valve lifter and the free rotation of an intake valve during engine operation. <P>SOLUTION: A valve gear includes: the valve lifter 6 integrally having a disk-shaped crown 10 at an axial end of a cylindrical part 9 and a projecting portion 11 formed at a back side of the crown; the intake valve 4 which is opened and closed while an end face of a stem end 4b abuts on a lower end face 11a of the projecting portion of the valve lifter; and a camshaft 2 having a drive cam 3 pressing the crown. The center line X of a crown face 10a of the valve lifter and the center line Y in a width direction of the cam face 3c of the driving cam are offset by α in an axial direction of the camshaft and a contact point S between the projecting portion and the stem end is offset in relation to the axis Z of a valve stem. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a valve operating apparatus for an internal combustion engine that opens and closes an engine valve via a valve lifter (tapet).

  As this type of conventional valve operating apparatus for an internal combustion engine, one described in the following Patent Document 1 previously filed by the present applicant is known.

  In brief, the valve operating apparatus includes a drive shaft that is rotationally driven by a crankshaft of an engine, a camshaft having an oscillating cam that opens and closes an intake valve, and the oscillating cam and the intake valve. And the rotational force of an eccentric cam provided on the outer periphery of the drive shaft is converted into a oscillating motion. A link mechanism for transmitting to the swing cam, and a variable mechanism for varying the lift characteristics of the intake valve in conjunction with the link mechanism.

  The center of the cam surface of the swing cam in the width direction is offset in the axial direction of the camshaft with respect to the center of the crown of the valve lifter.

  As a result, during the engine operation, the valve lifter smoothly rotates in the sliding hole of the cylinder head, thereby suppressing the occurrence of uneven wear between the crown surface and the cam surface of the swing cam.

JP 2000-230409 A

  However, in the conventional valve operating apparatus, no consideration is given to the rotation of the intake valve, and therefore the umbrella portion (valve face) of the intake valve is provided at the open end of the intake port. It is always seated at the same location on the annular valve seat. As a result, there is a risk that uneven wear or the like occurs between the umbrella portion and the valve seat.

  The present invention provides a valve operating apparatus that can suppress the occurrence of uneven wear with a valve seat by rotating an engine valve, which is an intake valve or an exhaust valve, in addition to a valve lifter during driving of the engine. The purpose is to do.

  According to the first aspect of the present invention, in particular, the center of the crown surface of the valve lifter and the center of the cam cam surface in the width direction are offset in the axial direction of the camshaft, and the protrusion of the valve lifter and the engine valve The stem end contact portion is offset with respect to the axis of the valve stem of the engine valve.

  According to a second aspect of the present invention, the axis of the valve stem of the engine valve and the center of the crown of the valve lifter are arranged on the same axis, and the end surface of the protrusion is formed into a spherical shape. The contact point between the end face of the engine valve and the tip end face of the stem end of the engine valve is offset with respect to the axis of the valve stem.

  According to a third aspect of the present invention, the protruding portion is arranged substantially coaxially with the center of the crown portion of the valve lifter, and the shaft center of the cylindrical portion of the valve lifter is connected to the valve stem via the sliding hole. It is characterized in that it is arranged offset in the axial direction of the camshaft with respect to the axis.

  According to the present invention, during rotation of the engine, free rotation of the valve lifter can be obtained and free rotation of the engine valve can also be obtained, so occurrence of uneven wear between the cam and the crown surface of the valve lifter. And the occurrence of uneven wear between the umbrella portion of the engine valve and the valve seat can be suppressed.

It is principal part sectional drawing which shows the time of valve closing of the intake valve in 1st Embodiment of the valve operating apparatus which concerns on this invention. It is the sectional view on the AA line of FIG. It is principal part sectional drawing which shows the time of valve opening of the intake valve in this embodiment. It is the BB sectional view taken on the line of FIG. It is principal part sectional drawing which shows the time of valve closing of the intake valve in 2nd Embodiment of this invention. It is CC sectional view taken on the line of FIG. It is principal part sectional drawing which shows the time of valve opening of the intake valve in this embodiment. It is the DD sectional view taken on the line of FIG.

  Embodiments of a valve operating apparatus for an internal combustion engine according to the present invention will be described below in detail with reference to the drawings.

[First embodiment]
1 to 4 show a first embodiment of the present invention, which is applied, for example, to the intake side of a V-type six-cylinder four-cycle gasoline engine, and rotates at the upper end of the cylinder head 1 via a bearing not shown. A camshaft 2 that is freely supported, a general egg-shaped drive cam 3 integrally provided on the outer periphery of the camshaft 2, and a combustion chamber of an intake port (not shown) formed inside the cylinder head 1 An intake valve 4 that opens and closes the opening end on the side and a sliding hole 5 formed in the upper end of the cylinder head 1 are slidably held, and the rotational force of the drive cam 3 is transmitted to the intake valve 4. And a valve lifter 6.

  The cylinder head 1 is formed of, for example, an aluminum alloy material. As shown in FIGS. 2 and 4, a concave portion serving as a relief portion of the cam nose portion 3 b when the drive cam 3 rotates is formed at the upper end portion of the sliding hole 5. A groove 5a is formed.

  The camshaft 2 is formed in a round bar shape with steel material, extends in the longitudinal direction of the engine, and receives rotational force from the crankshaft via a chain wound around a driven sprocket (not shown) provided at one end. The rotation speed is set to ½ of the crankshaft.

  The drive cams 3 are provided corresponding to the intake valves 4, respectively, and have a cylindrical base circle portion 3a formed along the outer peripheral surface of the camshaft 2, and are protruded from the outer peripheral surface of the base circle portion 3a. A cam nose portion 3b. A continuous outer peripheral surface of the base circle portion 3a and the cam nose portion 3b is configured as a cam surface 3c.

  The intake valve 4 is integrally formed on the front end side, and is provided integrally with an umbrella portion that is attached to and detached from an annular valve seat that is fixed to the opening end of the intake port, and an upper end of the umbrella portion. And a valve stem 4a slidably held on the cylinder head 1 via an outer cylindrical valve guide.

  A multi-stage disc-shaped spring retainer 8 that elastically holds the upper end of the valve spring 7 is integrally fixed to one end side of the valve stem 4a via a cotter (not shown).

  The valve lifter 6 is integrally formed of a steel material, and has a cylindrical portion 9 whose outer peripheral surface slides on the inner peripheral surface of the sliding hole 5 and a disc-like shape integrally provided on the upper end portion of the cylindrical portion 9. The crown portion 10 includes a projection portion 11 that is integrally provided on the back surface side opposite to the crown surface (upper surface) 10 a of the crown portion 10.

  The outer diameter of the cylindrical portion 9 is set slightly smaller than the inner diameter of the sliding hole 5 so that it is slid up and down while being held on the inner peripheral surface of the sliding hole 5 when the engine is driven. It has become. The cam surface 3c of the drive cam 3 is always in sliding contact with the crown surface 10a of the crown portion 10 when the engine is driven.

  The protrusion 11 is formed in a substantially cylindrical shape, and is formed on the lower end surface 11a formed in a spherical shape on the stem end 4b of the valve stem 4a of the intake valve 4 via the spring force of the valve spring 7. The end surface is in elastic contact, and the opening cam is transmitted to the intake valve 4 through the crown 10 and the protrusion 11 of the valve lifter 6 by the rotation of the drive cam 3.

  As shown in FIG. 1, the cylindrical portion 9 of the valve lifter 6 has a center line X camped from a center line Y in the width direction of the cam surface 3 c of the drive cam 3 when the intake valve 4 is closed. The shaft 2 is slightly offset in the axial direction by α. That is, for example, the axial position of the camshaft 2 is preliminarily shifted slightly by α from the normal position, or the sliding hole 5 is formed at a position that is α in advance from the normal position. By forming it slightly shifted in the axial direction of the shaft 2, the center line X of the cylindrical portion 9 and the center line Y in the width direction of the cam surface 3 c are offset in the axial direction of the cam shaft 2. .

  Further, the contact position (contact S) between the lower end surface 11a of the protrusion 11 and the upper end surface of the stem end 4b of the valve stem 4a is relative to the axis Z of the valve stem 4a (in FIG. 1, overlaps X). The camshaft 2 is offset by β in the axial direction. That is, the protrusion 11 is provided at a position slightly deviated to the left in the drawing by β from the center line X of the crown 10 in the state where the center axis Q is shown in FIG. The contact portion is offset from the axis Z of the valve stem 4a by β.

  Therefore, according to this embodiment, during operation of the engine, the camshaft 2 is rotated by the crankshaft, and the cam nose portion 3b (cam surface 3c) of the drive cam 3 is crowned as shown in FIGS. The valve lifter 6 is pushed down through the surface 10a, and a valve opening force acts on the intake valve 4. Then, a rotational force is generated in the valve lifter 6 by the large frictional force generated between the both 3c and 10a, and the valve lifter 6 rotates in one direction in the sliding hole 5.

  When the valve lifter 6 rotates, the contact S between the spherical lower end surface 11a of the protrusion 11 and the upper end surface of the stem end 4b of the valve stem 4a revolves around the axis Z of the valve stem 4a. For this reason, a rotational force is generated in the intake valve 4 by the frictional force acting on the contact S between the two, and the intake valve 4 can be stably rotated in one direction.

  As described above, by the free rotation of the valve lifter 6, uneven wear between the crown surface 10a of the valve lifter 6 and the cam surface 3c of the drive cam 3 is suppressed.

  Further, since the intake valve 4 can be freely rotated, uneven wear between the face surface on the outer periphery of the umbrella and the valve seat on the intake port side can be effectively suppressed.

  That is, as in the prior art, when the intake valve 4 does not rotate, uneven wear tends to occur between the umbrella portion of the intake valve and the valve seat, and the valve clearance changes with time. As a result, the engine speed becomes unstable. Further, in some cases, combustion gas leaks from the contact surface (seal surface) of both in the explosion process of the engine, causing combustion failure.

  In the present embodiment, as described above, since the intake valve 4 rotates freely, the contact surface between the umbrella part and the valve seat is made uniform, so that occurrence of uneven wear can be suppressed. The amount of wear on the face surface is reduced and durability can be improved.

  On the other hand, since the contact surface on the valve seat side is in contact with the entire face surface of the umbrella portion and is evenly contacted, the amount of wear at the portion is reduced and the durability is improved.

  The intake valve 4 tends to be difficult to rotate particularly in the low engine speed range. If the diesel engine or the gasoline engine generally used in the low engine speed is frequently used in the low engine speed range, the uneven wear may occur. Although it is likely to occur, the intake valve 4 can be forcibly rotated with a simple structure as in the present embodiment, so that it is possible to control the manufacturing cost in a low engine speed range regardless of diesel engine or gasoline engine. It is possible to effectively suppress uneven wear.

  Further, since the lower end surface 11a of the protrusion 11 is formed in a spherical shape, it is easy to make an offset arrangement with the upper end surface of the stem end 4b, and the contact S becomes a point contact so that the axis Z of the valve stem 4a is set. Since it revolves around the center, the rotational transmission force of the valve stem 4a is improved by the frictional force acting on the contact S, and the rotational performance of the intake valve 4 can be enhanced.

Furthermore, since the contact S is always offset during the opening period of the intake valve 4, the intake valve 4 can be stably rotated at the contact S by the rotation of the protrusion 11.
[Second Embodiment]
5 to 8 show a second embodiment of the present invention. The basic structures of the camshaft 2, the drive cam 3, the valve lifter 6 and the like are the same as those of the first embodiment, but the difference is that the drive cam 3 is different. The center line Y of the cam surface 3c in the width direction and the valve stem 4a axis Z of the intake valve 4 are arranged on the same axis, and the center line X of the cylindrical portion 9 of the valve lifter 6 (the crown 10) The center) is offset.

  More specifically, as shown in FIG. 5, when the intake valve 4 is closed, the axis Q of the protrusion 11 is arranged on the coaxial line on the center line X of the crown 10 of the valve lifter 6. The center line X and the axis Q on the same axis are the same as the center line Y on the cam surface 3c and the axis Z of the valve stem 4a on the same axis in the left direction of the cam shaft 2 by γ. Offset placement.

  Therefore, also in this embodiment, when the camshaft 2 is rotated by the crankshaft during operation of the engine, as shown in FIGS. 7 and 8, the cam nose portion 3b (cam surface 3c) of the drive cam 3 moves the crown surface 10a. Then, the valve lifter 6 is pushed down, and a valve opening force acts on the intake valve 4. Then, a rotational force is generated in the valve lifter 6 by the large frictional force generated between the both 3c and 10a, and the valve lifter 6 rotates in one direction in the sliding hole 5.

  When the valve lifter 6 rotates, the contact S between the spherical lower end surface 11a of the protrusion 11 and the upper end surface of the stem end 4b of the valve stem 4a revolves around the axis Z of the valve stem 4a. For this reason, a rotational force is generated in the intake valve 4 by the frictional force acting on the contact S between the two, and the intake valve 4 can be stably rotated in one direction.

  Therefore, as in the first embodiment, the free rotation of the valve lifter 6 suppresses uneven wear between the crown surface 10a of the valve lifter 6 and the cam surface 3c of the drive cam 3, and the intake valve 4 can also be freely rotated, so that uneven wear between the face surface of the outer periphery of the umbrella and the valve seat can be effectively suppressed.

  The present invention is not limited to the configuration of each of the embodiments described above, and can also be applied to a variable valve operating device that varies the operating angle and lift amount of the intake valve listed as the prior art as the valve operating device, for example. In addition to the general drive cam, the present invention can also be applied to those using a swing cam as in the prior art. When this swing cam is used, the rotation direction of the valve lifter changes and the rotation direction of the intake valve also changes, and there is no difference from the above embodiments effectively.

  Furthermore, it can of course be applied to exhaust valves in addition to intake valves, and can be applied to some engine valves in addition to all engine valves.

  Moreover, although the lower end surface of the protrusion is formed in a spherical shape, it can be formed in a flat surface shape.

DESCRIPTION OF SYMBOLS 1 ... Cylinder head 2 ... Cam shaft 3 ... Drive cam 4 ... Intake valve (engine valve)
4a ... Valve stem 4b ... Stem end 5 ... Sliding hole 6 ... Valve lifter 7 ... Valve spring 9 ... Cylindrical part 10 ... Crown part 11 ... Projection part 11a ... Lower end surface X ... Center line of valve lifter (cylindrical part) Y ... Center line in the width direction of the cam surface of the drive cam Z: Valve stem axis Q: Center line of the protrusion

Claims (3)

A cylindrical portion slidably in contact with the inner peripheral surface of the sliding hole formed in the cylinder head, a disc-shaped crown portion integrally formed at one axial end portion of the cylindrical portion, and a protrusion provided on the back side of the crown portion And a valve lifter comprising:
An engine valve that opens and closes while the tip end surface of the stem end is in contact with the end surface of the protrusion of the valve lifter;
A camshaft having a cam that presses a crown surface of the crown portion with a cam surface;
A valve operating apparatus for an internal combustion engine comprising:
The center of the crown surface of the valve lifter and the center in the width direction of the cam surface of the cam are offset in the axial direction of the cam shaft, and
2. A valve operating apparatus for an internal combustion engine, wherein a protruding portion of the valve lifter and an abutting portion of the stem end of the engine valve are arranged offset with respect to an axis of the valve stem of the engine valve. The valve operating apparatus for an internal combustion engine according to claim 1,
The axis of the valve stem of the engine valve and the center of the crown of the valve lifter are arranged on the same axis, and the end surface of the projection is formed in a spherical shape, and the spherical end surface and the stem end of the engine valve A valve operating apparatus for an internal combustion engine, wherein a contact point with a tip surface of the internal combustion engine is offset with respect to an axis of the valve stem. The valve operating apparatus for an internal combustion engine according to claim 1,
The protruding portion is arranged substantially coaxially with the center of the crown portion of the valve lifter, and the axial center of the cylindrical portion of the valve lifter is arranged in the axial direction of the camshaft with respect to the axis of the valve stem through the sliding hole. A valve operating apparatus for an internal combustion engine, wherein the valve operating apparatus is offset.

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