JP2010096137A - Valve gear for internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a valve gear for an internal combustion engine reducing uneven wear of a valve seat and a valve head seated on and separated from the valve seat. <P>SOLUTION: In the valve gear for the internal combustion engine including the valve head part positioned at an end part of a valve stem driven and reciprocated by a cam driven and rotated by a crankshaft of the engine, the valve seat which a seat surface formed on an outer circumference of the valve head part is seated on and separated from, and a cylinder head provided with the valve seat, and opening and closing a gas passage by making the seat surface of the valve head part seated on and separated from the valve seat, the valve seat includes an abutment surface which the seat surface of the valve head part is seated on and separated from, the abutment surface includes an inner contact part contacting an inner diameter side of the seat surface and an outer contact part contacting an outer diameter side of the seat surface. Rigidity of the inner contact part is reduced, the outer contact part and the inner contact part have equivalent rigidity, and a valve seat shape at an upper part of the abutment surface is changed. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention provides a valve head portion positioned at the end of a valve stem that is driven to reciprocate by a cam that is driven to rotate by a crankshaft of an engine, a seat seat formed on the outer periphery of the valve head portion, and a valve seat that is attached to and detached from The present invention relates to a valve device for an internal combustion engine that includes a cylinder head including the valve seat, and a seat surface of a valve head portion is attached to and detached from the valve seat to open and close a gas passage.

  In an intake valve operating device or an exhaust valve operating device for an engine, a tappet in which the motion of an intake cam or an exhaust cam rotated by a crankshaft is attached to the tip of a valve rod of the intake valve or exhaust valve The air supply valve or the exhaust valve is transmitted to the air supply valve or the exhaust valve to open and close the air supply valve or the exhaust valve.

Here, a conventional valve device will be described with reference to FIG. FIG. 12 is a schematic side view showing the vicinity of a valve head portion of a conventional valve device.
As shown in FIG. 12, a valve device such as an air supply valve or an exhaust valve includes a valve rod 64 that is reciprocally driven by a cam that is rotationally driven by an engine crankshaft, and a valve head portion that is positioned at an end of the valve rod 64. 62, a seat surface 66 formed on the outer periphery of the valve head portion, and a valve seat 68 attached to and detached from the seat surface 66. In the valve device, the seat surface 66 of the valve head portion is attached to and detached from the valve seat 68 to open and close the gas passage.

  As shown in FIG. 12, these air supply valves and exhaust valves have their valve heads in contact with the valve seats when they are opened and closed.

  A valve that is worn in this way cannot be used any more if it is worn beyond a certain level, and needs to be replaced, resulting in cost. For this reason, it is necessary to take measures against wear in order to extend the life of the valve. Patent Document 1 (Japanese Patent Laid-Open No. 5-340214) is disclosed as a measure against this wear.

  Patent Document 1 discloses a piston chamber into which a working fluid is introduced, a piston that is provided at the upper end of the intake and exhaust valves and moves in the axial direction by the pressure of the working fluid in the piston chamber to move the intake and exhaust valves. A space that is provided inside the piston and receives the working fluid introduced into the piston chamber, and is formed at the top of the piston in communication with the space, and the working fluid is inclined with respect to the axial direction of the piston. And an injection hole for rotating the piston and the intake / exhaust valve by injecting in a direction. As a result, the working fluid introduced into the piston chamber moves the piston in the axial direction by the pressure, and is injected obliquely from the injection hole or the injection groove of the piston in the piston chamber to rotate the piston.

On the other hand, the present applicant has proposed the invention disclosed in Patent Document 2 (Japanese Patent Laid-Open No. 62-30837) as a countermeasure against wear.
According to Patent Document 2, the valve seat part formed on the valve head part and the material of the contact surface of the valve seat attached to and detached from the valve seat part are selected, and the contact surface of the valve seat is angled. The contact with the valve seat is made stronger.

JP-A-5-340214 JP 62-30837 A

However, in Patent Document 1, an attempt is made to reduce wear by rotating the valve stem by the pressure of the working fluid. However, rotation of the valve stem alone is not sufficient as a countermeasure against wear, and it is operated for a long time. Occurrence of wear due to inevitably occurs, and uneven wear occurs in the valve head and the valve seat.
In addition, Patent Document 2 selects a valve seat portion formed on the valve head portion, a material for a contact surface of the valve seat attached to and detached from the valve seat portion, and provides an angle to the contact surface of the valve seat. Although it is beneficial for reducing the wear of the valve seat and the valve head, further measures are required to further reduce the wear rate.
SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a valve device for an internal combustion engine that reduces uneven wear of a valve seat and a valve head portion attached to and detached from the valve seat.

In order to achieve such an object, the present invention provides a valve umbrella portion positioned at an end portion of a valve rod that is driven to reciprocate by a cam that is rotationally driven by a crankshaft of an engine, and a seat surface formed on the outer periphery of the valve umbrella portion. In a valve device for an internal combustion engine comprising: a valve seat that is attached and detached; and a cylinder head that is provided with the valve seat, and a seat surface of a valve umbrella portion is attached to and detached from the valve seat to open and close a gas passage.
The valve seat is provided with a contact surface that is attached to and detached from the seat surface of the valve head portion, and the corresponding surface is an inner contact portion that contacts the inner diameter side of the seat surface and an outer contact that contacts the outer diameter side of the seat surface. The inner contact portion has a reduced rigidity, and the outer contact portion and the inner contact portion are formed with the same rigidity, and the valve seat shape above the contact surface is changed. To do.

According to the present invention, the valve seat is provided with a contact surface to be attached to and detached from the seat surface of the valve head portion, the corresponding surface is an inner contact portion that contacts the inner diameter side of the seat surface, and an outer diameter of the seat surface. An outer contact portion that comes into contact with the side, and the rigidity of the inner contact portion is reduced, and the outer contact portion and the inner contact portion are formed with the same rigidity, so that the valve seat above the contact surface The shape is easily deformed to warp outward, and the situation where only the inner portion of the above-described valve head portion is worn is improved, so that uneven wear is reduced, and wear of the valve seat and the valve head portion can be reduced. it can.
For example, even if the valve head part is deformed due to the pressure from the bottom of the combustion chamber, the valve seat is deformed following the deformation of the valve head part, and the valve head part contacts the valve seat. As a result, the wear rate can be reduced. In the deformation of the valve seat, the contact force is further dispersed by warping so that the end of the warp comes to the outer diameter side from the line extending from the outer contact portion of the valve seat to the upper side of the valve seat.

The valve stem is provided with a valve stem rotating means provided on the valve stem to rotate the valve stem about an axis, and the valve seat is fitted to the cylinder head with a gap interposed therebetween and rotated about the axis of the valve stem. It is characterized by being.
In this way, by rotating not only the valve stem but also the valve seat, uneven wear of the valve seat and the valve head portion attached to and detached from the valve seat is reduced, and the wear of the valve seat and the valve head portion can be made uniform.

And a valve seat rotating means provided at an upper portion of the valve seat for rotating the valve seat about an axis of the valve stem, wherein the valve seat is rotated by being attached to and detached from a seat surface of the valve head portion. To do.
In this way, by providing the rotating means in the valve seat, not only the valve stem but also the valve seat is rotated, so that uneven wear can be reduced. Moreover, since it is worn out uniformly, the contact at the contact surface of the valve seat is improved.

The valve stem projection further includes a valve stem projection provided at a lower portion of the valve stem and projecting toward the valve seat, and a valve seat projection provided on the valve seat so as to face the valve stem projection. And the valve seat protrusion is engaged to transmit the rotation of the valve stem to the valve seat, and the valve seat is rotated together with the valve rod.
As described above, the valve stem includes a valve stem projection provided at a lower portion of the valve stem and projecting toward the valve seat, and a valve seat projection provided on the valve seat so as to face the valve stem projection. By rotating the valve stem by engaging the projection and the valve seat projection, the valve stem is rotated together with the valve seat, so that uneven wear can be reduced. Further, the wear is made uniform.

Furthermore, a valve guide cylinder that is formed on the outer periphery of the valve stem and positions the seating position of the seat surface, and a valve guide cylinder rotating means that is provided at the upper end portion of the valve guide cylinder and rotates the valve guide cylinder around the axis. The lower end of the valve guide tube and a valve seat located on the outer periphery of the valve guide tube are connected, and the valve seat is rotated together with the valve guide.
Thus, since not only the valve stem but also the valve guide cylinder rotating means for rotating the valve guide cylinder with the valve seat is provided and the valve seat is rotated together with the valve guide, uneven wear can be reduced. Further, the wear is made uniform. The valve guide cylinder rotating means uses a rotator to improve rotation stability, but a rotating device such as a motor can be used instead.

A valve guide tube formed on an outer periphery of the valve stem for positioning a seating position of the seat surface; a valve guide tube protrusion provided at a lower end portion of the valve guide tube and protruding toward the valve seat; A valve seat projection provided on the valve seat facing the valve guide tube projection, and a valve guide tube rotating means provided on the upper end of the valve guide tube for rotating the valve guide tube about its axis,
The valve guide tube projection and the valve seat projection are engaged to transmit rotation of the valve guide tube to the valve seat, and the valve seat is rotated together with the valve guide tube.
Accordingly, since not only the valve stem but also a valve guide cylinder rotating means for rotating the valve guide cylinder with the valve seat is provided and the valve seat is rotated together with the valve guide, uneven wear can be reduced. Further, the wear is made uniform.

As described above, according to the present invention, the valve seat is provided with a contact surface to be attached to and detached from the seat surface of the valve head portion, the corresponding surface is an inner contact portion that is in contact with the inner diameter side of the seat surface, and the seat An outer contact portion that contacts the outer diameter side of the surface, and the rigidity of the inner contact portion is reduced, and the outer contact portion and the inner contact portion are formed to have the same rigidity, so that the contact surface Since the upper valve seat shape is easily deformed so as to bend outward and only the inner part of the above-described valve head part is worn, uneven wear is reduced, and wear of the valve seat and the valve head part is reduced. Can be reduced. Further, the valve seat can be deformed following the deformation of the valve head portion, so that concentration of contact between the valve head portion and the valve seat can be avoided.
Further, by rotating the valve stem and the valve seat, not only the valve stem but also the valve seat is rotated. Therefore, uneven wear of the valve seat and the valve umbrella portion attached to and detached from the valve seat is reduced, and the valve seat and the valve umbrella are reduced. The wear of the part can be made uniform. Therefore, since it is worn uniformly, the contact at the contact surface of the valve seat is improved.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the drawings. However, the dimensions, materials, shapes, relative arrangements, etc. of the components described in this embodiment are not intended to limit the scope of the present invention unless otherwise specified, but are merely illustrative examples. Only.
FIG. 1 is a schematic longitudinal sectional view of the vicinity of a valve device of an internal combustion engine according to an embodiment of the present invention, FIG. 2 is a rotating device according to an embodiment of the present invention, and FIG. FIG. 4B is an enlarged side view taken along line VV in FIG. 4A, and FIG. 4C is a half sectional view showing the valve fully open. 3 is a side view showing the vicinity of the valve head portion of the valve device according to the first embodiment, where (a) shows the valve seat before deformation, (b) shows the valve seat after deformation, and FIG. 4 shows the second embodiment. FIG. 5 is a schematic enlarged view of the W portion in FIG. 4, FIG. 6 is a side view showing the valve device according to Embodiment 3, and FIG. 7 is a schematic enlarged view of the X portion in FIG. 8 is a cross-sectional view taken along line YY in FIG. 6, FIG. 9 is a side view showing the valve device according to Embodiment 4, FIG. 10 is a cross-sectional view taken along line ZZ in FIG. It is sectional drawing which shows another form of.

First, a valve device for an internal combustion engine according to an embodiment of the present invention will be described with reference to FIG.
FIG. 1 is a schematic longitudinal sectional view of the vicinity of a valve device of an internal combustion engine according to an embodiment of the present invention, where 100 is an engine, 110 is a cylinder head, and 112 is a combustion chamber formed in a cylinder of the engine 100. . Reference numeral 103 denotes an exhaust port formed in each cylinder head 101, 104 denotes an exhaust valve that opens and closes the exhaust port 103, 101 denotes an air supply port, and 102 denotes an air supply valve. In this embodiment, the exhaust valve 104 is attached to one cylinder. A four-valve type valve operating apparatus having two and two air supply valves is provided. Reference numeral 102 denotes an exhaust valve spring.

Reference numeral 109 denotes a push rod (push bar) connected to an exhaust cam (not shown), and 107 denotes a rocker arm. Reference numeral 105 denotes a bridge in which upper ends of the exhaust valve 104 and the supply valve 102 are fixed. The bridge 105 is guided by a support shaft 111 fixed to the upper surface of the cylinder head 110, and the exhaust valve 104 and the supply valve 102. It reciprocates with the air valve 102.
An adjustment screw 112 is screwed into the rocker arm 107 on the bridge 105 side, and the tip of the adjustment screw 112 is connected to the upper surface of the bridge 105 via a tappet 106. The lower part of the tappet 106 forms a certain tappet clearance and rests on the upper surface of the bridge 105.

  In such a valve device, the exhaust cam is rotationally driven by a crankshaft (not shown), and the rocker arm 107 is swung around a support shaft of a rocker bracket (not shown) by the reciprocating motion of the bush rod 109. The bridge 105 and the exhaust valve 104 are pushed down against the spring force of the exhaust valve spring 113, and the exhaust valve 104 opens away from the valve seat.

Next, a rotating device used for the valve device of the internal combustion engine as described above, specifically, a valve rotator will be described with reference to FIG.
The valve rotator 50 shown in FIG. 2 (a) is fixed to the shaft end of the engine valve 51 via a pair of cotters 52, and has a rotator main body having an outward flange at the upper end, and a cylindrical portion of the rotator main body. A dish-like retainer 54 fitted in the vertical direction and externally fitted so as to be relatively rotatable, and formed on the lower surface of the outward ridge facing the circumferential direction, and the upper surface (groove bottom surface) is inclined downward in a certain direction. Between the plurality of arc-shaped guide grooves 55 having inclined surfaces 55a to be rolled, the steel balls 56 accommodated in the guide grooves 55 so as to be capable of rolling, and the deep ends of the guide grooves 55. A coil spring 57 that is provided and constantly urges the steel ball 56 toward the shallow end of the guide groove 55; A dish with inner and outer peripheral edges locked between A root 58, is placed on the upper surface of the disc spring 58, and is constituted out with a ball race (not shown) provided on the upper surface of the annular groove that the lower surface can be fitted for the steel ball 56.

The operation from when the valve in FIG. 2 (a) is closed to when the valve is fully opened in FIG. 2 (c) starts when the engine valve 51 starts to be pressed by a rocker arm (not shown) and the load of the valve spring 59 increases. The retainer 54 moves upward against the disc spring 58. At the same time, the steel ball 56 is pressed through a ball race in contact with the disc spring 58 and tries to roll upward on the inclined surface 55 a of the guide groove 55 against the coil spring 57.
As a result, the rotator body is horizontally rotated in the direction indicated by the arrow in FIG. 2B by the horizontal force caused by the rolling of the steel ball 56, and the engine valve 51 is also rotated around the axis via the cotter 52. Rotated.

  Further, when the load of the valve spring 59 is reduced when the valve is closed in FIG. 2A, the coil spring 57 is also restored according to the restoration of the disc spring 58. Since the force of the coil spring 57 is weaker than that of the disc spring 58, the phenomenon of returning rotation does not occur.

(Embodiment 1)
The valve device according to Embodiment 1 will be described with reference to FIG. 3A and 3B are side views showing the vicinity of the valve head portion of the valve device according to the first embodiment. FIG. 3A shows the state before the valve seat is deformed, and FIG. 3B shows the state after the valve seat is deformed.
The valve device shown in FIG. 3 (a) includes a valve stem 4 that is reciprocally driven by a cam that is rotationally driven by a crankshaft of an engine, a valve umbrella portion 2 that is positioned at an end of the valve rod 4, and the valve umbrella portion. 2 is composed of a seat surface 6 formed on the outer periphery of the seat 2 and a valve seat 10 attached to and detached from the seat surface 6.

Further, the valve seat 10 is provided with a contact surface that is attached to and detached from the seat surface 6 of the valve head portion 2, and the corresponding surface is an inner contact portion 12 that contacts the inner diameter side of the seat surface 6, and the outer diameter of the seat surface 6. The outer contact part 14 which contacts a side is provided.
In the present embodiment, the radius of the upper side of the inner contact portion 12 is reduced, and the metal is bent outward, thereby reducing the rigidity of the inner contact portion 12 and facilitating deformation. That is, the outer contact portion 14 is formed with the same rigidity as the inner contact portion 12, and the valve seat shape above the contact surface is changed as shown by the broken line portion shown in FIG. . As a result, uneven wear is reduced, and wear of the valve seat and the valve head portion can be reduced.

  Here, the change in the valve seat shape will be described. As shown by the broken line portion in FIG. 3B, the shape is changed by bending the valve seat 10 outward. This warpage has a small radius of curvature of the warped portion, a long arc length of the warped portion, a larger cross section of the upper opening 3 than a cross section of the lower opening 5, and a cross-sectional portion having a diameter indicated by reference numeral 7 is retained. It is formed by a configuration in which the member is slightly thinned. Specifically, the height H is less than half of the inner diameter of the lower opening 5, the inner diameter of the upper opening 3 is larger than the inner diameter of the lower opening 5, and is formed between the lower opening 5 and the upper opening 3. It is determined by the cross-sectional portion 7 having an inner diameter smaller than the inner diameter of the lower opening 5.

(Embodiment 2)
Next, the valve device according to the second embodiment will be described with reference to FIGS. FIG. 4 is a side view showing the valve device according to the second embodiment, and FIG. 5 is a schematic enlarged view of a W portion in FIG.
The valve device shown in FIG. 4 includes a valve stem 4 that is reciprocally driven by a cam that is rotationally driven by a crankshaft of an engine, a valve umbrella portion 2 that is positioned at an end of the valve rod 4, and an outer periphery of the valve umbrella portion 2. , A valve seat 10 that is attached to and detached from the seat surface 6, and a valve rotator 50 that is provided at the upper end of the valve rod 4.
Further, a valve seat rotating means provided on the valve seat 10 for rotating the valve seat 10 around the axis of the valve rod 4 is provided. In this embodiment, the rotator 8 is used as the valve seat rotating means.

By driving the valve stem 4 up and down, the seat surface 6 and the valve seat 10 formed on the outer periphery of the valve head portion 2 are attached and detached. When the valve head portion 2 and the valve seat 10 come into contact with each other, the valve seat 10 rises slightly together with the valve stem 4, and the force is transmitted to the rotator 8. Thereafter, the rotator 8 rotates the valve seat 10 when separating from the valve head portion 2 and the valve seat 10. In this way, not only the valve stem but also the valve seat is rotated, and concentration of contact between the valve head portion and the valve seat can be avoided, so that uneven wear can be reduced.
The operations of the valve rotator 50 and the rotator 8 are the same as those in FIG.

  Further, as shown in FIG. 5, the valve seat 10 is fitted to the cylinder head 110 with a gap interposed therebetween, and the valve seat 10 can be rotated by the gap. Further, the valve seat 10 is not dropped by the fitting portion.

(Embodiment 3)
Moreover, the valve apparatus which concerns on Embodiment 3 is demonstrated using FIGS. 6 is a side view showing a valve device according to Embodiment 3, FIG. 7 is a schematic enlarged view of a portion X in FIG. 6, and FIG. 8 is a cross-sectional view taken along line YY in FIG.
As in the second embodiment, the valve device shown in FIG. 6 includes a valve stem 4 that is reciprocally driven by a cam that is rotationally driven by the crankshaft of the engine, a valve umbrella portion 2 that is positioned at the end of the valve stem 4, A seat surface 6 formed on the outer periphery of the valve head portion 2, a valve seat 10 attached to and detached from the seat surface 6, and a valve rotator 50 provided at the upper end portion of the valve stem 4. The operation of the valve rotator 50 is the same as that in FIG.

As shown in FIGS. 7 and 8, the valve stem 4 is provided at a lower portion thereof and protrudes toward the valve seat 10. The valve stem projection 18 faces the valve seat 10 and faces the valve stem projection 18. And a valve seat projection 16 provided.
When the valve stem 4 is rotated by the valve rotator 50, the valve stem protrusion 18 is also rotated accordingly. Further, the valve stem projection 18 and the valve seat projection 16 are engaged, and the rotation of the valve stem 4 is transmitted to the valve seat 10. In this way, the valve seat 10 is rotated together with the valve stem 4.

Further, as shown in FIG. 7, the valve seat 10 is fitted to the cylinder head 110 with a gap interposed therebetween, and the valve seat 10 can be rotated by the gap.
From the above, since not only the valve stem but also the valve seat is rotated and concentration of contact between the valve head portion and the valve seat can be avoided, uneven wear can be reduced.

(Embodiment 4)
Moreover, the valve apparatus which concerns on Embodiment 4 is demonstrated using FIGS. 9 is a side view showing a valve device according to Embodiment 4, FIG. 10 is a cross-sectional view taken along line ZZ in FIG. 9, and FIG. 11 is a cross-sectional view showing another form of FIG.
As in the second embodiment, the valve device shown in FIG. 9 includes a valve stem 4 that is reciprocally driven by a cam that is rotationally driven by the crankshaft of the engine, a valve head portion 2 that is positioned at an end of the valve stem 4, A seat surface 6 formed on the outer periphery of the valve head portion 2, a valve seat 10 attached to and detached from the seat surface 6, and a valve rotator 50 provided at the upper end portion of the valve stem 4.

Furthermore, a valve guide cylinder 20 formed on the outer periphery of the valve stem 4 for positioning the seating position of the seat surface 6 and a valve guide provided at the upper end of the valve guide cylinder 20 for rotating the valve guide cylinder 20 about the axis. Cylinder rotating means.
The valve guide cylinder rotating means improves the rotation stability by using the rotator 22, but a rotating device such as a motor can be used instead. The operations of the valve rotator 50 and the rotator 22 are the same as those in FIG.

FIG. 10 is a cross-sectional view taken along line ZZ in FIG. 9 when a valve guide with a valve seat in which the lower end portion of the valve guide cylinder 20 and the valve seat 10 located on the outer periphery thereof are connected is used. 9 are denoted by the same reference numerals for the sake of brevity, 4 is a valve rod, 10 is a valve seat, and 20 is a valve guide.
By adopting such a configuration, not only the valve stem but also the valve seat is rotated together with the valve guide, so that concentration of contact between the valve head portion and the valve seat can be avoided, so that uneven wear can be reduced. .

Moreover, the structure shown in FIG. 11 is also used suitably as another form of FIG. That is, as shown in FIG. 11, the valve guide tube 22 is provided separately from the valve seat 10, and the valve guide tube projection 21 and the valve seat projection 23 are engaged to rotate the valve guide tube 22 so that the valve guide tube 22 rotates. The valve seat 10 is rotated together with the valve guide tube 22 by being transmitted to the seat 10.
By adopting such a configuration, as in FIG. 10, not only the valve stem but also the valve seat is rotated together with the valve guide, so that concentration of contact between the valve head portion and the valve seat can be avoided. Can be reduced.

Although not shown, in both FIGS. 10 and 11, the valve seat is fitted to the cylinder head with a gap therebetween, and the valve seat can be rotated by the gap.
Thus, in addition to the means for changing the shape of the valve seat as described in the first embodiment, by rotating the valve seat as described in the second to fourth embodiments, Uneven wear is reduced.

  The present invention is useful when applied to a valve device of an internal combustion engine that reduces uneven wear of a valve seat and a valve head portion attached to and detached from the valve seat.

1 is a schematic longitudinal sectional view in the vicinity of a valve device of an internal combustion engine according to an embodiment of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS It is a rotating apparatus which concerns on one Embodiment of this invention, (a) is a half sectional view which shows the time of valve closing, (b) is an enlarged side view in alignment with the VV line in (a), (c) is a valve full open. It is a half sectional view showing time. It is a side view which shows the valve head part vicinity of the valve apparatus which concerns on Embodiment 1, (a) is before a valve seat deformation | transformation, (b) is a figure which shows after a valve seat deformation | transformation. It is a side view which shows the valve apparatus which concerns on Embodiment 2. FIG. It is a schematic enlarged view of the W section in FIG. It is a side view which shows the valve apparatus which concerns on Embodiment 3. FIG. It is a schematic enlarged view of the X section in FIG. It is sectional drawing which follows the YY line in FIG. It is a side view which shows the valve apparatus which concerns on Embodiment 4. It is sectional drawing which follows the ZZ line in FIG. It is sectional drawing which shows another form of FIG. It is a schematic side view which shows the valve head part vicinity of the conventional valve apparatus.

Explanation of symbols

2 Valve Umbrella 4 Valve Rod 6 Seat Surface 10 Valve Seat 20 Valve Guide 50 Valve Rotator

Claims (6)

A valve head portion positioned at an end of a valve stem that is driven to reciprocate by a cam that is rotationally driven by a crankshaft of an engine, a valve seat that is attached to and detached from a seat surface formed on the outer periphery of the valve head portion, and the valve seat A valve device for an internal combustion engine that opens and closes a gas passage by attaching and detaching a seat surface of a valve head part to the valve seat.
The valve seat is provided with a contact surface that is attached to and detached from the seat surface of the valve head portion, and the corresponding surface is an inner contact portion that contacts the inner diameter side of the seat surface and an outer contact that contacts the outer diameter side of the seat surface. The inner contact portion has a reduced rigidity, and the outer contact portion and the inner contact portion are formed with the same rigidity, and the valve seat shape above the contact surface is changed. A valve device for an internal combustion engine.   Provided with valve stem rotating means provided on the valve stem for rotating the valve stem about an axis, and the valve seat is fitted to the cylinder head with a gap and rotated about the axis of the valve stem. 2. The valve device for an internal combustion engine according to claim 1, wherein:   A valve seat rotating means provided at an upper portion of the valve seat and rotating the valve seat about an axis of a valve stem, wherein the valve seat is rotated by being attached to and detached from a seat surface of a valve head portion. Item 3. A valve device for an internal combustion engine according to Item 2. A valve stem projection provided at a lower portion of the valve stem and projecting toward the valve seat; and a valve seat projection provided on the valve seat to face the valve stem projection.
The internal combustion engine according to claim 2, wherein the valve stem projection and the valve seat projection are engaged to transmit rotation of the valve stem to the valve seat, and the valve seat is rotated together with the valve stem. Valve device. A valve guide cylinder that is formed on the outer periphery of the valve stem and positions a seating position of the seat surface; and a valve guide cylinder rotating unit that is provided at an upper end portion of the valve guide cylinder and rotates the valve guide cylinder around an axis,
3. The valve device for an internal combustion engine according to claim 2, wherein a lower end portion of the valve guide cylinder and a valve seat located on an outer periphery thereof are connected, and the valve seat is rotated together with the valve guide. A valve guide tube formed on an outer periphery of the valve stem for positioning a seating position of the seat surface; a valve guide tube protrusion provided at a lower end portion of the valve guide tube and protruding toward the valve seat; and the valve guide A valve seat projection provided on the valve seat facing the tube projection, and a valve guide cylinder rotating means provided on the upper end of the valve guide cylinder for rotating the valve guide cylinder about the axis,
The valve guide tube projection and the valve seat projection are engaged to transmit rotation of the valve guide tube to the valve seat, and the valve seat is rotated together with the valve guide tube. A valve device for an internal combustion engine.

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