JP2020118062A - Valve structure of engine - Google Patents

Abstract

To easily attach a cotter and a retainer to a valve system.SOLUTION: A valve structure comprises a valve member 10 having an umbrella part 12 at one end of an axial valve system 11, and a retainer 30 attached to an external periphery of the other end of the valve system 11 via a cotter 20. An entire shape of the cotter 20 is symmetrical across the axial center. The cotter 20 has a protrusion 21a protruding to the inside in a radial direction in the axial center, and is symmetrical across the axial center. An external peripheral face 22 of the cotter 20 comprises a first face face-contacting with an internal peripheral face 31 of the retainer 30, and a second face symmetrical to the first face with a center in an axial direction sandwiched therebetween. By this constitution, the cotter 20 can be attached to the valve system 11 without being limited in a normal attachment direction.SELECTED DRAWING: Figure 1

Description

The present invention relates to an engine valve structure.

BACKGROUND ART Conventionally, as an intake/exhaust valve of an engine, for example, a valve (hereinafter, referred to as a “valve member”) in which an umbrella portion which is a valve body portion is provided at one end of a shaft-shaped valve stem is disclosed in Patent Document 1. It is used. The valve stem is inserted into a valve insertion hole formed in the cylinder and is capable of moving forward and backward in the axial direction with respect to the cylinder.

The valve member is biased by the elastic force of the valve spring in a direction in which the umbrella portion closes the valve hole. Further, a pressing force acts on the other end of the valve stem, that is, the stem end that is the end opposite to the side where the umbrella is provided, by the action of the cam. The intake/exhaust valve is opened and closed by the valve stem moving forward and backward due to the elastic force of the valve spring and the pressing force of the cam, and the umbrella portion moving toward and away from the valve hole.

The elastic force of the valve spring acts on the valve stem via a cotter and a retainer attached to the valve stem. The cotter is attached to the other end of the valve stem. The retainer is attached to the valve stem via a cotter. One end of the valve spring is supported by the retainer and the other end is supported by the cylinder. With such a mode, the elastic force of the valve spring acts on the valve member via the cotter and the retainer.

Here, the cotter is a split collet divided into two parts having a conical outer peripheral surface, an inner peripheral surface contacting the outer peripheral surface of the valve stem, and a protrusion protruding radially from the inner peripheral surface. The retainer is an annular member having an inner peripheral surface facing the outer peripheral surface of the cotter. The inner peripheral surface of the retainer is a conical surface corresponding to the outer peripheral surface of the cotter. The outer peripheral surface of the cotter is in surface contact with the inner peripheral surface of the retainer, and the retainer is attached to the valve stem via the cotter.

JP, 2005-183677, A

By the way, as described above, the cotter has an outer peripheral surface that is a conical surface, and is formed such that the diameter gradually decreases from the other end to the one end in the axial direction of the cotter. That is, the cotter has an asymmetrical shape with the center in the axial direction sandwiched, and the cotter is attached such that the diameter-reduced side of the cotter faces the umbrella portion side of the valve member and the diameter-expanded side faces the valve stem end side. Here, the correct mounting direction of the cotter with respect to the valve stem is referred to as "regular mounting direction" for convenience of description.

Here, if the cotter is attached to the valve stem in a direction opposite to the above-described regular attachment direction, the outer peripheral surface of the cotter and the inner peripheral surface of the retainer will not fit properly. Therefore, the retainer cannot be properly attached to the valve stem.

When assembling or servicing the engine, it is necessary for the operator to visually confirm the mounting direction of the cotter. However, if the confirmation is insufficient, there is a possibility that the assembly work may proceed with the cotter attached in the wrong direction. When the cotter is erroneously assembled, it is necessary to disassemble the parts again and reassemble the cotter so that the mounting direction of the cotter is the regular mounting direction, which increases the number of working steps. In addition, since the cotter is a small component compared to the size of the operator's hand, it is complicated to attach and detach the cotter. Further, if the cotter is forcibly inserted into the inner side of the retainer while the mounting direction is wrong, the cotter may be deformed and the parts may be difficult to remove.

Therefore, an object of the present invention is to facilitate attachment of a cotter and a retainer to a valve stem.

In order to solve the above problems, a valve structure of an engine of the present invention is a valve member having an umbrella portion at one end of a shaft-shaped valve stem, and a retainer attached to the outer periphery of the other end of the valve stem via a cotter. And the cotter has a protrusion projecting radially inward at the center in the axial direction, and the protrusion enters the groove formed on the outer periphery of the valve stem, whereby the valve stem and the The movement of the cotter in the axial direction is restricted, the protrusion is symmetrical with the center in the axial direction sandwiched, and the outer peripheral surface of the cotter is on the inner peripheral surface of the retainer in a state where the protrusion enters the groove. A configuration including a first surface that comes into surface contact with the first surface and a second surface that is symmetrical with respect to the first surface with the axial center interposed therebetween is adopted.

Here, the outer peripheral surface of the cotter and the inner peripheral surface of the retainer are in surface contact with each other by the uneven portion that meshes in the radial direction, and the outer peripheral surface of the cotter and the inner peripheral surface of the retainer are in contact with each other about the axis. It is possible to employ a configuration in which the length is set to be longer than the circumferential length at the maximum diameter portion of the contact portion between the outer peripheral surface of the cotter and the inner peripheral surface of the retainer.

Further, the cotter has the other end projecting from the other end of the retainer in a state where the projecting portion is inserted into the groove portion, and the cotter and the retainer are axially opposed to each other on an outer peripheral surface of the cotter. It is possible to employ a configuration including a mark portion whose position is visually recognizable.

Furthermore, it is possible to adopt a configuration in which a gap that narrows toward the one end in the axial direction is interposed between the second surface and the inner peripheral surface of the retainer.

According to the present invention, the cotter is used as a valve stem by adopting a symmetric configuration with the protrusion of the cotter and the first surface and the second surface provided to sandwich the protrusion, with the axial center of the cotter being sandwiched. At the time of mounting, it became possible to install without limiting the mounting direction to a fixed direction. This makes it easier to avoid erroneous assembly during the maintenance work of the valve structure, and improves work efficiency. Therefore, the cotter and the retainer can be easily attached to the valve stem.

It is sectional drawing of the valve structure which concerns on 1st embodiment of this invention. It is sectional drawing which shows the cotter and the retainer of the valve structure which concern on 1st embodiment of this invention. It is a disassembled perspective view of the valve structure which concerns on the 2nd Embodiment of this invention. It is sectional drawing which shows the valve structure which concerns on the 2nd Embodiment of this invention. FIG. 5A is a sectional view taken along line VV of FIG. 4, and FIG. 5B is a partially enlarged view of FIG. 5A showing uneven portions of a cotter and a retainer. It is sectional drawing which shows the valve structure which concerns on the 3rd Embodiment of this invention.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 shows a valve structure provided in the engine. In the drawings, only the main part of one cylinder is shown.

The port 3 in the cylinder 1 has an intake port and an exhaust port. A fuel injection device (not shown) for injecting fuel into the intake port is provided in the intake port, and the fuel is injected into intake air in the intake port to form a mixture. The formed air-fuel mixture moves to the combustion chamber, burns in the combustion chamber, and then its exhaust gas is discharged to the outside through the exhaust port.

Valves are provided on both the intake port and the exhaust port. The valve on the intake port side is provided so that the valve hole of the intake port can be opened and closed. When this valve is opened, the valve hole is opened and a gas flow path is formed from the intake port to the combustion chamber. When the valve is closed, the valve hole is closed and the space between the intake port and the combustion chamber is closed.

The valve on the exhaust port side is provided so that the valve hole of the exhaust port can be opened and closed. When the valve is opened, the valve hole is opened to form a gas discharge path from the combustion chamber to the exhaust port. When this valve is closed, the valve hole is closed and the space between the combustion chamber and the exhaust port is sealed.

The air gap between the piston and the cylinder is ensured by an oil film of engine oil. When the valve on the intake port side and the valve on the exhaust port side are closed, the combustion chamber is sealed.

Hereinafter, the valve structure of the engine will be described by taking the intake port as an example, but the exhaust port may have a similar structure. The engine is not limited to one in which the fuel injection device is provided in the intake port, but may be a cylinder direct injection engine that is provided in the combustion chamber and injects fuel into intake air in the combustion chamber.

The valve structure shown in FIG. 1 includes a valve 10 (hereinafter referred to as “valve member 10 ”), a valve spring 40 connected to the valve member 10 via a cotter 20 and a retainer 30, and a shaft end of the valve member 10. And a tappet 50 facing each other.

The valve member 10 is a metal member having a shaft-shaped valve stem 11 and an umbrella portion 12 provided at one axial end thereof. Here, the direction along the axis of the valve member 10 is referred to as the “axial direction”. Further, the direction orthogonal to the axial direction is called "radial direction". Further, the direction that goes around the axis is referred to as the “axis direction”.

A cam 60 is arranged above the tappet 50. The retainer 30 and the cotter 20 are annular members, and the valve stem 11 is inserted inside the inner peripheral surface 31 of the retainer 30 via the cotter 20. The valve spring 40 is a compression coil spring fixed to both the cylinder 1 and the retainer 30 so as to surround the valve stem 11. The valve spring 40 biases the valve member 10 upward in the drawing via the retainer 30 and the cotter 20.

The cylinder 1 is provided with a valve insertion hole 1a penetrating from above the cylinder 1 to the port 3. The valve stem 11 is inserted into the valve insertion hole 1a via a valve stem guide 11d which is a metal cylinder. As a result, the valve member 10 is supported so as to be capable of moving up and down in the axial direction with respect to the cylinder 1.

As shown in FIGS. 1 and 2, between the other end, which is the end on the opposite side to the axial umbrella portion 12 of the valve stem 11, and from the other end to the center in the axial direction, the vertical cross section passing through the axial center has an arc shape. Thus, the groove portion 11a that is depressed is provided.

As shown in FIG. 1, the umbrella portion 12 provided at one end of the valve stem 11 has an umbrella shape in which the diameter is radially expanded in the axial direction. The outer diameter of the lower end of the umbrella portion 12 in the figure is larger than the inner diameter of the valve hole 4 of the port 3.

The edge of the valve hole 4 of the port 3 is a chamfered inclined surface. A face surface 12a that is inclined so as to correspond to the inclined surface is provided at an edge portion on the upper side in the drawing of the umbrella portion 12.

When the valve member 10 rises and the face surface 12a contacts the edge of the valve hole 4, the port 3 is closed. When the valve member 10 descends, the face surface 12a is separated from the edge of the valve hole 4, and the port 3 is opened. In this way, the valve member 10 opens and closes the port 3.

FIG. 2 shows a state in which the retainer 30 is attached to the groove portion 11 a of the valve member 10 via the cotter 20.

The cotter 20 is a split collet that has a conical outer peripheral surface 22 and an inner peripheral surface 21 that contacts the outer peripheral surface of the valve stem 11. The overall shape of the cotter 20 is symmetric with respect to the axial center thereof. The valve stem 11 is inserted inside the inner peripheral surface 21 of the cotter 20. The inner peripheral surface 21 of the cotter 20 and the outer peripheral surface of the valve stem 11 are in contact with each other.

As shown in FIGS. 1 and 2, the cotter 20 is formed so that the diameter thereof is gradually reduced from the apex portion 22 a located at the center in the axial direction on the outer peripheral surface 22 to both ends in the axial direction. The outer peripheral surface 22 has a first surface 22b located on the umbrella portion 12 side in the axial direction from the apex portion 22a and a second surface 22c located on the stem end side in the axial direction. The first surface 22b and the second surface 22c are formed symmetrically in the axial direction with the center in the axial direction interposed therebetween. Between the second surface 22c and the inner peripheral surface 31 of the retainer 30, there is a gap that narrows toward one end in the axial direction.

The cotter 20 has a protrusion 21 a that radially protrudes from the center position of the inner peripheral surface 21 in the axial direction. The contour shape of the protrusion 21a is, like the contour shape of the groove portion 11a, an arcuate vertical cross section passing through the axis. The protrusions 21a are symmetrical with respect to the axial center of the cotter 20. The radial distance from the inner peripheral surface 21 to the projecting end of the projecting portion 21a is equal to the depth of the groove 11a. The protrusion 21a is in the groove 11a. As a result, the cotter 20 is restricted from moving in the axial direction with respect to the valve member 10.

As described above, the protrusions 21a are symmetrical with respect to the axial center of the cotter 20. Further, the first surface 22b and the second surface 22c are symmetrical with the axial center of the cotter 20 in between. Therefore, even when the mounting direction of the cotter 20 is axially opposite to the direction shown in FIGS. 1 and 2, the first surface 22b and the second surface 22c have no difference from the embodiment shown in FIGS. ing. That is, even if the mounting directions are opposite, the first surface 22b corresponds to the apex portion 12a side in the axial direction on the umbrella portion 12 side, and the second surface 22c corresponds to the surface located on the stem end side in the axial direction.

The retainer 30 is an annular member having an inner peripheral surface 31 that faces the outer peripheral surface 22 of the cotter 20. Further, the retainer 30 has a projecting portion 32 that projects radially from the axially upper end of the outer peripheral surface in the figure. The inner peripheral surface 31 of the retainer 30 is a conical surface corresponding to the outer peripheral surface 22 of the cotter 20. The cotter 20 and the valve member 10 are inserted inside the inner peripheral surface 31 of the retainer 30. The first surface 22b of the cotter 20 is in surface contact with the inner peripheral surface 31. Thus, the retainer 30 is attached to the valve stem 11 via the cotter 20.

A valve spring 40 is arranged below the protruding portion 32 of the retainer 30. The valve spring 40 is a compression spring wound counterclockwise (counterclockwise) in a plan view from the tappet 50 side. The winding direction of the valve spring 40 may be clockwise (right-handed).

As shown in FIG. 1, the valve spring 40 has its lower end, that is, the end near the combustion chamber, supported by the cylinder 1 via a valve spring seat (not shown). The upper end portion of the valve spring 40 is fixed to the protruding portion 32 of the retainer 30. Therefore, the valve spring 40 is connected to the valve member 10 via the retainer 30 and the cotter 20. The valve member 10 is biased upward by the elastic force of the valve spring 40.

As shown in FIG. 1, the tappet 50 disposed on the axially upper side of the valve member 10 rises from the end wall portion 51 facing the other end of the valve stem 11 and the peripheral edge of the end wall portion 51 toward the umbrella portion 12 side. It is a cup-shaped member having a cylindrical peripheral wall portion 52. The tappet 50 fits into a guide hole (not shown) formed in the cylinder head and slides on the inner surface of the guide hole.

The end wall portion 51 is a plate body having a circular shape in a plan view, and has a wall thickness that increases from the outside in the axial direction to the center. As shown in FIGS. 1 and 2, an annular protrusion that rises toward the valve stem 11 is provided at the center of the inner surface of the end wall portion 51 in plan view. The end surface of the valve stem 11 contacts the end surface of the protrusion of the tappet 50.

The upper cam 60 of the tappet 50 in the axial direction slides on the outer surface of the end wall portion 51. The cam 60 is provided on the camshaft, and power transmission to the camshaft is performed by connecting a sprocket provided on the camshaft side and a sprocket provided on the crankshaft side with a timing chain or the like. There is. The distance from the rotation center of the cam 60 to the contact point with the end wall portion 51 changes depending on the rotation position of the cam 60. As the distance to the contact point increases, the force with which the cam 60 presses the tappet 50 downward in the drawing increases. Therefore, the force with which the cam 60 presses the tappet 50 changes in accordance with the rotation of the cam 60.

The valve member 10 is biased upward by the elastic force of the valve spring 40, and the valve member 10 is pressed downward from the cam 60 via the tappet 50. When the pressing force of the cam 60 is less than the elastic force of the valve spring 40, the valve spring 40 extends and the valve member 10 moves up. When the pressing force of the cam 60 exceeds the elastic force of the valve spring 40, the valve spring 40 is compressed and the valve member 10 descends. In this way, the valve member 10 is raised or lowered by the rotation of the cam 60 to open and close the valve hole 4.

As described above, the cotter 20 has a symmetrical structure with the first surface 22b and the second surface 22c provided with the protruding portion 21a interposed therebetween, with the axial center of the cotter being interposed therebetween. Further, the protrusions 21a are symmetric with respect to the axial center of the cotter 20. Therefore, even when the mounting directions of the cotter 20 are opposite, there is no difference from the embodiment shown in FIGS. 1 and 2, and the first surface 22b comes into surface contact with the inner peripheral surface 31. If the cotter has a conventional valve structure, this mounting direction is limited to the regular mounting direction. However, by adopting the configuration of the present embodiment, whether the mounting direction of the cotter 20 to the valve stem 11 is the direction of FIGS. It can be attached to the valve stem 11. As a result, the workability of attaching the retainer 30 to the valve stem 11 is improved, and the cotter 20 and the retainer 30 are easily attached to the valve stem 11.

Next, a second embodiment of the present invention is shown in FIGS. As described above, in the first embodiment, the gap that narrows toward the one end in the axial direction is provided between the second surface 22c and the inner peripheral surface 31 of the retainer 30. Therefore, the second surface 22c and the inner peripheral surface 31 of the retainer 30 are not in contact with each other. Therefore, the outer peripheral surface 22 has a smaller contact area with the retainer 30 than the outer peripheral surface of the conventional cotter. Therefore, the contact area is increased to increase the friction generated between the inner peripheral surface 31 and the outer peripheral surface 22.

The outer peripheral surface 22 of the cotter 20 has an uneven portion 22d that is uneven in the radial direction. The concavo-convex portion 22d has a plurality of convex portions 22e arranged in parallel in the circumferential direction of the outer peripheral surface 22 at equal intervals and concave portions 22f located between the respective convex portions.

The inner peripheral surface 31 of the retainer 30 has a concavo-convex portion 31a that is concavo-convex in the radial direction and meshes with the concavo-convex portion 22d of the cotter 20. The concavo-convex portion 31a has a plurality of convex portions 31b arranged side by side in the axial direction of the inner peripheral surface 31 and concave portions 31c located between the respective convex portions 31b. The axial width of the convex portion 31b is equal to the axial width of the concave portion 22f of the cotter 20. The axial width of the recess 31c of the retainer 30 is equal to the axial width of the projection 22e of the cotter 20. The radial length from the bottom surface of the concave portion 31c to the projection end surface of the convex portion 31b is equal to the radial length from the projection end surface of the convex portion 22e of the cotter 20 to the bottom surface of the concave portion 22f. The side surface 22g of the convex portion 22e on the axial direction side and the side surface 31e of the convex portion 31b on the axial direction side are in surface contact with each other. The contact length around the axis between the outer peripheral surface 22 of the cotter 20 and the inner peripheral surface 31 of the retainer 30 is the circumference at the maximum diameter portion of the contact portion between the outer peripheral surface 22 of the cotter 20 and the inner peripheral surface 31 of the retainer 30. It is set longer than the length of S1. According to such an aspect, the outer peripheral surface 22 of the cotter 20 and the inner peripheral surface 31 of the retainer 30 are in surface contact with each other by the uneven portions 22d and 31a meshing with each other in the radial direction. In addition, in FIG. 5B, a gap is formed between the projecting end surface of the convex portion 22e and the bottom surface of the concave portion 31c, but they may be in surface contact with each other. Similarly, the tip end surface of the convex portion 31b and the bottom surface of the concave portion 22f may also be in surface contact with each other.

In the present embodiment, the outer peripheral surface 22 is different from the outer peripheral surface 22 in which the uneven portions 22d and 31a are not provided and the contact portion between the outer peripheral surface 22 and the inner peripheral surface 31 is in the same position as S1 shown in FIG. The total contact area with the inner peripheral surface 31 is larger. Therefore, the friction between the outer peripheral surface 22 and the inner peripheral surface 31 becomes large. From this, even if a load exceeding the assumption is applied to the retainer 30, the retainer 30 is unlikely to come off the valve stem 11.

Next, FIG. 6 shows a third embodiment of the present invention. The cotter 20 of each of the above-described embodiments is located radially inward of the inner peripheral surface 31 of the retainer 30. Therefore, it is difficult for an operator to confirm the relative positions of the cotter 20 and the retainer 30 in the axial direction. For this reason, it is difficult to confirm whether the retainer 30 is in the normal position where it can be attached to the valve stem 11, and there is a possibility that the cotter 20 may be insufficiently inserted or excessively inserted. Therefore, in the present embodiment, it is assumed that the relative positions of the cotter 20 and the retainer 30 in the axial direction can be confirmed.

As shown in FIG. 6, the other end of the cotter 20 projects more toward the stem end side in the axial direction than the other end of the retainer 30. The outer peripheral surface 22 has a mark portion 70 that allows the relative position of the cotter 20 and the retainer 30 in the axial direction to be visually recognized. The mark portion 70 is an annular groove that is recessed in the radial direction, and is provided on both the first surface 22b and the second surface 22c so as to be vertically symmetrical with the axial center of the cotter 20 interposed therebetween. There is.

The mark portion 70 on the second surface 22c may be located anywhere on the second surface 22c as long as it is visible from the outside of the retainer 30. For example, as shown in FIG. 6, when the retainer 30 is attached to the valve stem 11, the axial position of the mark portion 70 coincides with a virtual line L indicating an extension line of the upper end surface of the retainer 30 in the drawing. Can be adopted. The operator can confirm the relative positions of the retainer 30 and the cotter 20 by this mark portion 70, and can confirm whether the retainer 30 is attached to the valve stem 11 at a normal position.

Note that, in the engine valve structure according to the third embodiment, FIG. 6 shows a mode in which the outer peripheral surface 22 of the cotter 20 and the inner peripheral surface 31 of the retainer 30 have uneven portions 22d and 31a as in the second embodiment. ing. However, as in the first embodiment, the outer peripheral surface 22 and the inner peripheral surface 31 may not have the uneven portions 22d and 31a. Further, the mark portion 70 is an annular groove, but it does not have to be annular. Further, it is not limited to the groove, and may be a linear mark drawn by paint or the like.

In each of the above-described embodiments, the groove portion 11a is a groove whose longitudinal cross section passing through the shaft center has an arc shape, but it may be a groove having a rectangular cross section, for example. The same applies to the protrusion 21a that enters the groove.

Further, in each of the above-described embodiments, as the cotter 20, a member in which the entire shape of the cotter 20 is symmetrical between the one end side and the other end side with the center in the axial direction sandwiched is employed. 21a, the 1st surface 22b, and the 2nd surface 22c should just be symmetrical about the axial center of the cotter 20, respectively, and include the part which is not symmetrical across the axial center in the other part. Good. However, it is desirable that the non-symmetrical portions have a slight difference across the axial center.

Although the embodiments of the present invention have been described above, the scope of the present invention is not limited to the above embodiments, and various modifications can be applied.

1 cylinder 10 valve member 11 valve stem 11a groove 12 umbrella 20 cotter 21 inner peripheral surface 21a protrusion 22 outer peripheral surface 22b first surface 22c second surface 30 retainer 31 inner peripheral surface

Claims (4)

A valve member having an umbrella portion at one end of a shaft-shaped valve stem,
A retainer attached to the outer periphery of the other end of the valve stem via a cotter,
Equipped with
The cotter has a protrusion projecting inward in the radial direction at the center in the axial direction, and the protrusion enters the groove formed on the outer circumference of the valve stem, whereby the valve stem and the cotter are axially aligned. Movement is restricted,
The protrusions are symmetrical with respect to the center in the axial direction, and the outer peripheral surface of the cotter has a first surface that comes into surface contact with an inner peripheral surface of the retainer in a state where the protrusions enter the groove portion, and A valve structure for an engine, comprising: a first surface; and a second surface that is symmetrical with respect to the center in the axial direction. The outer peripheral surface of the cotter and the inner peripheral surface of the retainer are in surface contact with each other by an uneven portion that meshes in the radial direction,
The contact length around the axis between the outer peripheral surface of the cotter and the inner peripheral surface of the retainer is longer than the circumferential length at the maximum diameter portion of the contact portion between the outer peripheral surface of the cotter and the inner peripheral surface of the retainer. The engine valve structure according to claim 1, wherein the valve structure is set. The cotter has the other end protruding from the other end of the retainer in a state where the protrusion is in the groove.
3. The engine valve structure according to claim 1, wherein a mark portion is provided on an outer peripheral surface of the cotter so that a relative position between the cotter and the retainer in the axial direction can be visually recognized. The engine valve structure according to any one of claims 1 to 3, wherein a gap that narrows toward the one end in the axial direction is provided between the second surface and the inner peripheral surface of the retainer.

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