GB2560087A

GB2560087A - Intake valve of internal combustion engine

Info

Publication number: GB2560087A
Application number: GB1721992.4A
Authority: GB
Inventors: Maruyama Katsumi; Ishikawa Takeshi; Yuri Nobuyuki; Shimizu Motohiro
Original assignee: Honda Motor Co Ltd
Current assignee: Honda Motor Co Ltd
Priority date: 2016-12-27
Filing date: 2017-12-27
Publication date: 2018-08-29
Anticipated expiration: 2037-12-27
Also published as: JP2018105232A; GB2560087B; GB201721992D0; CN108266244B; JP6650390B2; CN108266244A

Abstract

An intake valve 10 of an internal combustion engine, eg a gas-fuelled engine, has an uneven portion 14 formed on a flared slope portion 12 having a slope which gradually expands from the valve stem (11, fig.1) toward the valve seat portion13, and in which a slope angle of the flared slope portion 12 changes at the uneven portion 14. An oil-repellent coating layer 20, eg with fluorine, is formed on at least part of the flared slope portion 12 including the uneven portion 14 to level unevenness at the uneven portion 14 to reduce deposits where they might otherwise adhere or accumulate. The coating layer 20 may be applied also to part of the valve stem 11. The thickness of the coating layer 20 may change between the uneven portion 14 and the valve stem. The uneven portion (14A, fig.3) may comprise two steps. The flared slope portion (12B, fig.4) may be concave.

Description

(71) Applicant(s):

Honda Motor Co., Ltd.

(Incorporated in Japan)

1-1 Minami-Aoyama 2-chome, Minato-ku, Tokyo 107-8556, Japan (51) INT CL:

FOIL 3/04 (2006.01) (56) Documents Cited:

DE 003517914 A1 JP 010237310 A JP 2004100478 A (58) Field of Search:

INT CL FOIL

FOIL 3/20 (2006.01)

JP 030249314 A JP 2014062522 A US 4811701 A1

Other: EPODOC, WPI, Patent Fulltext (72) Inventor(s):

Katsumi Maruyama Takeshi Ishikawa Nobuyuki Yuri Motohiro Shimizu (74) Agent and/or Address for Service:

Dehns

St. Bride's House, 10 Salisbury Square, LONDON, EC4Y 8JD, United Kingdom (54) Title of the Invention: Intake valve of internal combustion engine Abstract Title: l.c. engine intake valve with oil-repellent coating (57) An intake valve 10 of an internal combustion engine, eg a gas-fuelled engine, has an uneven portion 14 formed on a flared slope portion 12 having a slope which gradually expands from the valve stem (11, fig. 1) toward the valve seat portion13, and in which a slope angle of the flared slope portion 12 changes at the uneven portion 14. An oil-repellent coating layer 20, eg with fluorine, is formed on at least part of the flared slope portion 12 including the uneven portion 14 to level unevenness at the uneven portion 14 to reduce deposits where they might otherwise adhere or accumulate. The coating layer 20 may be applied also to part of the valve stem 11. The thickness of the coating layer 20 may change between the uneven portion 14 and the valve stem. The uneven portion (14A, fig.3) may comprise two steps. The flared slope portion (12B, fig.4) may be concave.

1/4

FIG.l

2/4

FIG.2

3/4

CL

FIG.3

4/4

FIG.4

INTAKE VALVE OF INTERNAL COMBUSTION ENGINE [0001]

The present invention relates to an intake valve of an internal combustion engine.

[0002]

It is known that deposits adhere to or accumulate on a valve head of an intake valve which opens and closes a combustion chamber of an internal combustion engine. The deposits accumulate in such a way that engine oil or the like adheres to a valve flared portion, and gets highly viscous under a high-temperature environment resulting from combustion in the engine and solidifies as time goes by. When the deposits accumulate on the flared portion of the intake valve, not only is the sucking performance of the intake valve reduced in association with a reduction in surface properties thereof, but also some of the accumulated deposits are caused to separate from the flared portion of the intake valve by the reciprocating movement thereof to adhere to a valve seal portion, reducing the sealing properties. This reduces the output of the engine, which is not preferable.

[0003]

In a valve described in JP-A-H03-249314, with a view to reducing deposits adhered and accumulated on the valve, a coating portion including a deposit adhesion preventing surface layer made up of a highly water repellent substance and an oxidative compound which emits far infrared rays is provided on a surface of the valve. In an intake valve described in JP-A-H06-272520, there are provided a prime coat which is formed by applying an oxide-based coating which emits far infrared rays whose wavelength almost coincides with a far infrared ray absorbing wavelength of deposits when heated under a situation where the intake valve is being used from a stem to a flared portion of the intake valve and a top coat which is formed by applying a heat resistant coating to a surface of the prime coat.

[0005]

As described in JP-A-H03-249314 or JP-A-H06-272520, the adhesion or accumulation of deposits can be reduced by applying the coatings on the surface of the valve. However, in the event that an uneven portion where deposits can adhere and accumulate exists on a valve head portion, the effect of reducing the accumulation of deposits provided by the application of the coatings are limited because the uneven portion is subject to an accumulation of deposits. In particular, an internal combustion engine using gaseous fuel has a small effect of a so-called self-washing function of gaseous fuel as compared with liquid fuel. An intake valve of the gaseous fuel internal combustion engine is subject to an accumulation of deposits.

[0006]

An object of at least the preferred embodiments of the invention is to provide an intake valve of an internal combustion engine, which can reduce deposits adhered or accumulated on a surface of the intake valve even though an uneven portion is present at a portion of the intake valve where deposits can accumulate.

[0007]

According to the invention, there is provided an intake valve (for example, an intake valve 10, 10A, 10B in an embodiment) of an internal combustion engine (for example, an internal combustion engine 1 in an embodiment), which is provided at an inlet (for example, an inlet 2m in an embodiment) of a combustion chamber (for example, a combustion chamber 5 in an embodiment) of the internal combustion engine to open and close a communication between an intake port (for example, an intake port 2 in an embodiment) and the combustion chamber, having:

an uneven portion (for example, an uneven portion 14, 14A in an embodiment) formed on a flared slope portion (for example, a flared slope portion 12, 12B in an embodiment) having a slope which gradually expands from a valve stem portion (for example, a valve stem portion 11 in an embodiment) for reciprocating in an axial direction toward a valve seal portion (for example, a valve seal portion 13 in an embodiment) for contacting with an inlet seal portion (for example, an inlet seal portion 2s in an embodiment) of the combustion chamber, and in which a slope angle of the flared slope portion changes at the uneven portion, wherein an oil-repellent coating layer (for example, an oil-repellent coating layer 20, 20A, 20B in an embodiment) is formed on at least part of the flared slope portion including the uneven portion to level unevenness at the uneven portion.

[0008]

An angle (for example, an angle Θ1 in an embodiment) formed by a surface of the coating layer and an axis of the valve stem portion may be larger than an angle (for example, an angle Θ2 in an embodiment) of the flared slope portion excluding the uneven portion relative to the valve stem portion.

[0009]

The coating layer may have a portion covering the uneven portion where increases in thickness to curve a surface of the coating layer.

[0010]

The coating layer may be formed on the flared slope portion and a part of a surface of the valve stem portion which connects to the flared slope portion.

[0011]

The coating layer may be a fluorine coating layer.

[0012]

The internal combustion engine may be a gaseous fuel engine.

[0013]

According to the invention, in the intake valve, even though the flared slope portion has the uneven portion where is subject to an accumulation of deposits, it is possible to reduce deposits adhered or accumulated on the intake valve because the oil-repellent coating layer is formed on the flared slope portion including the uneven portion to level the unevenness at the uneven portion. Since the accumulation of deposits can be reduced, it enables to suppress the occurrence of a phenomenon in which accumulated deposits strip off and are caught between the valve seal portion and the inlet to thereby reduce a hermetic performance of the intake valve. As a result, it is possible to prevent an output reduction of the internal combustion engine associated with the reduced hermetic performance of the intake valve.

[0014]

In embodiments in which the slope angle of the coating layer relative to an axis of the valve stem portion is larger than a slope angle of the flared slope portion relative to the axis of the valve stem portion, it makes the structure that a fluid such as engine oil which is eventually transformed to deposits is difficult to stay on the coating layer, as compared with a case where the slope angle of the coating layer formed to level the unevenness at the uneven portion is smaller than the slope angle of the flared slope portion. Therefore, it is possible to further reduce the accumulation of deposits.

[0015]

In embodiments in which the coating layer has a portion covering the uneven portion where increases in thickness to curve the surface of the coating layer, it makes the structure that the slope angle of the thicker portion relative to the axis of the valve stem portion is larger and therefore a fluid such as engine oil which is eventually transformed to deposits is difficult to stay on the coating layer. Therefore, it is possible to further reduce the accumulation of deposits.

[0016]

In embodiments in which the coating layer is not formed on an overall portion of the intake valve, but is formed on a part of the intake valve which is exposed to the combustion chamber and the intake port such as the flared slope portion and a part of a surface of the valve stem portion which connects to the flared slope portion where deposits tend to adhere highly as compared with the other portions of the intake valve, since the coating layer is formed only on the portions of the intake valve where deposits tend to adhere highly, a fluorine coating material is prevented from being used 5 wastefully, thereby making it possible to enhance the cost effectiveness of the coating layer.

[0017]

In embodiments in which a fluorine coating layer is used as the coating layer, since the fluorine coating layer has high slipperiness, the adhesion of deposits or the like can be further suppressed. In addition, where particles contained in the fluorine coating material are minute, the surface of the coating layer can be finished in a good condition by application of a fluorine coating even though a surface to which a coating layer is applied is rough in a working process (a grinding process) occurring before a coating process when the intake valve is machined. Therefore, no process is required after the coating layer is formed.

[0018]

In embodiments in which the internal combustion engine is a gaseous fuel engine, the intake valve is used as an intake valve for a gaseous fuel engine which is driven with a gaseous fuel. The washing effect of the gaseous fuel engine is less than that of an internal combustion engine driven with a liquid fuel, and an intake valve is subject to an accumulation of deposits in the gaseous fuel engine. However, since the intake valve is configured to suppress the accumulation of deposits thereon, the intake valve is affected less by deposits even when the intake valve is used in the gaseous fuel engine for long period of time.

[0019]

Fig. 1 is a sectional view of an intake valve of an internal combustion engine according to a first embodiment.

Fig. 2 is an enlarged sectional view of a main part of the intake valve according to the first embodiment.

Fig. 3 is an enlarged sectional view of a main part of an intake valve according to a second embodiment.

Fig. 4 is an enlarged sectional view of a main part of an intake valve according to a third embodiment.

Hereinafter, embodiments of the invention will be described with reference to the drawings and by way of example only.

[0020] (First Embodiment)

Referring to Figs. 1 and 2, an intake valve of an internal combustion engine according to a first embodiment of the invention will be described. Fig. 1 is a sectional view of the intake valve of the internal combustion engine according to the first embodiment. Fig. 2 is an enlarged sectional view of a main part of the intake valve according to the first embodiment.

[0021]

As shown in Fig. 1, an intake valve 10 of an internal combustion engine 1 is provided to open and close an inlet 2m of an intake port 2 in a cylinder head la. The intake valve 10 has a valve head 15 and a valve stem portion 11. The valve head 15 is provided to match the inlet 2m which communicates with a combustion chamber 5 of the internal combustion engine 1. The valve stem portion 11 is provided to cross the intake port 2 and to project outside of the cylinder head la. The valve stem portion 11 is supported by a stem guide 4 to slide and reciprocate in an axial direction. The valve stem portion 11 is normally actuated in a closing direction in which the valve stem portion 11 closes the inlet 2m by a valve spring 8 which is disposed between a valve stem end llue and a side wall of the cylinder head la. Consequently, the valve head 15 ensures the hermeticity of the combustion chamber 5 by a valve seal portion 13 around an outer circumference of a distal end of the valve head 15 being brought into abutment with an intake port seal portion 2s. On the other hand, the valve stem end llue is pushed down at appropriate timings by a rotating cam (not shown) which is provided on a camshaft, so that the intake valve 10 is caused to move in the axial direction, whereby the inlet 2m is opened, allowing air or air-fuel mixture to be sucked into the combustion chamber 5.

[0022]

A flared slope portion 12 is formed on a side of the valve head 15 which faces the intake port 2. The flared slope portion 12 has a slope which gradually expands from the valve stem portion 11 toward the valve seal portion 13 for contacting with the intake port seal portion 2s of the combustion chamber 5. A recessed uneven portion is formed at a lower portion of the flared slope portion 12. A slope angle of the flared slope portion 12 changes at the uneven portion 14. In other words, a first boundary portion 14a and a second boundary portion 14b, which make up the uneven portion 14, are formed at a boundary portion with the valve seal portion 13 in the flared slope portion 12 and the vicinity of the boundary portion. A flat surface portion 14e, 8 which slopes at an angle smaller than the slope angle of the flared slope portion 12, is formed between the first boundary portion 14a and the second boundary portion 14b.

[0023]

The uneven portion 14 is formed because the valve seal portion 13 needs a higher machining accuracy as compared with the flared slope portion 12 in the valve head 15, and a larger mechanical strength is required on the side of the valve seal portion 13. Namely, the valve seal portion 13 and the inlet seal portion 2s need highly accurate surface properties to ensure the hermetic performance of the valve head 15. A distal end portion of the valve head 15 on the side where the valve seal portion 13 is provided needs a certain angle to ensure a certain thickness. Because of this, the uneven portion 14 is formed at the boundary portion with the valve seal portion 13 in the flared slope portion 12 of the valve head 15. However, the uneven portion 14 is subject to an accumulation of the deposits, as compared with the other portions of the flared slope portion 12 where no uneven portion is formed.

[0024]

In this embodiment, an oil-repellent coating layer 20 is formed on the flared slope portion 12 including the uneven portion 14 and a part of a surface of the valve stem portion 11 which connects to the flared slope portion 12. The coating layer 20 is formed so as to level unevenness at the uneven portion 14. The coating layer 20 has a thickness dl at the first boundary portion 14a of the uneven portion 14 which is good enough for the coating layer 20 to fill or level the unevenness at the uneven portion 14. The coating layer 20 is formed at the second boundary portion 14b so that a surface 20s of the coating layer 20 continues from an end face of the valve seal portion 13.

[0025]

The thickness of the coating layer 20 is not limited specifically, and hence, any thickness can be adopted, provided that the uneven portion 14 is leveled by the thickness. The thickness of the coating layer 20 can be set as required according to conditions such as the size or shape of the uneven portion 14. Consequently, in the coating layer 20, the thickness dl at the portion near the uneven portion 14 does not necessarily have to be the same as a thickness d2 at a portion near the valve stem portion 11.

[0026]

There is imposed no specific limitation on a material for the coating layer 20, provided that a material selected has oil repellency and heat resistance. However, a fluorine coating layer is desirable which can provide good slipperiness and workability for the surface 20s.

[0027]

Thus, as has been described heretofore, in this embodiment, in the intake valve

10, even though the flared slope portion 12 has the uneven portion 14 where is subject to the accumulation of deposits, it is possible to reduce deposits adhered or accumulated on the intake valve 10 because the oil-repellent coating layer 20 is formed on the flared slope portion 12 including the uneven portion 14 to level the unevenness at the uneven portion 14. Since the accumulation of deposits can be reduced, it enables to suppress the occurrence of a phenomenon in which accumulated deposits strip off and are caught between the valve seal portion 13 and the inlet 2m to thereby reduce the hermetic performance of the intake valve 10. As a result, it is possible to prevent an output 10 reduction of the internal combustion engine 1 associated with the reduced hermetic performance of the intake valve 10.

[0028]

Additionally, as to the range where the coating layer 20 is formed, the coating layer 20 is not formed on an overall portion of the intake valve 10, but is formed in a limited portion of the intake valve 10 where is exposed to the combustion chamber 5 and the intake port 2 such as the flared slope portion 12 and a non-sliding portion 1 Is of the valve stem portion 11 which does not slide against the stem guide 4. In this way, since the coating layer 20 is formed only on the portion of the intake valve 10 where deposits tend to adhere highly, a fluorine coating material is prevented from being used wastefully, thereby making it possible to enhance the cost effectiveness of the coating layer 20.

[0029]

Since the fluorine coating layer which is used as the coating layer 20 has high slipperiness, the adhesion of deposits or the like can be further suppressed. In addition, since particles contained in the fluorine coating material are minute, the surface of the coating layer 20 can be finished in a good condition by application of the fluorine coating even though a surface to which the coating layer 20 is applied is rough in the working process (the grinding process) occurring before the coating process when the intake valve 10 is machined. Therefore, no process is required after the coating layer is formed.

[0030]

The intake valve 10 of this embodiment is preferably used as an intake valve of an internal combustion engine (a gaseous fuel engine) driven with a gaseous fuel such as propane gas. The washing effect of the gaseous fuel engine is less than that of an internal combustion engine driven with a liquid fuel, and an intake valve is subject to an accumulation of deposits in the gaseous fuel engine. However, since the intake valve 10 of this embodiment is configured to suppress the accumulation of deposits thereon, the intake valve 10 is affected less by deposits even when the intake valve 10 is used in the gaseous fuel engine for long period of time.

[0031] (Second Embodiment)

Fig. 3 is an enlarged sectional view of a main part of an intake valve according to a second embodiment. The intake valve 10A of the second embodiment differs from the intake valve 10 of the first embodiment in configuration of an uneven portion 14A and a coating layer 20A. The remaining features of the intake valve 10A of the second embodiment are similar to those of the intake valve 10 of the first embodiment, and hence, in Fig. 3, like reference numerals are given to like constituent elements to those of the first embodiment shown in Fig. 1 or 2.

[0032]

As shown in Fig. 3, the uneven portion 14A of this embodiment is formed into a step-like configuration having two steps, and has a first boundary portion 14a, a second boundary portion 14b, a third boundary portion 14c, and a fourth boundary portion 14d. In the uneven portion 14A, a flat surface portion 14f, which slopes at an angle smaller than a slope angle of the flared slope portion 12, is formed between the 12 first boundary portion 14a and the third boundary portion 14c. A flat surface portion 14g, which slopes at an angle smaller than the slope angle of the flared slope portion 12, is formed between the fourth boundary portion 14d and the second boundary portion

14b.

[0033]

In this embodiment, similar to the first embodiment, the oil-repellent coating layer 20A is formed on the flared slope portion 12 including the uneven portion 14A and a part of a surface of the valve stem portion 11 which connects to the flared slope portion 12. The coating layer 20A is formed so as to level unevenness at the uneven portion 14A. The coating layer 20A has a thickness at the first boundary portion 14a of the uneven portion 14A which is good enough for the coating layer 20A to fill or level the unevenness at the uneven portion 14A. The coating layer 20A is formed at the second boundary portion 14b so that the surface 20s of the coating layer 20A continues from an end face of the valve seal portion 13.

[0034]

The coating layer 20A is formed on the flared slope portion 12 so that a portion near the valve stem portion 11 is thicker than a portion near the uneven portion 14A. Namely, the coating layer 20A has the configuration that the thickness of the coating layer 20A increases gradually from the portion near the uneven portion 14A toward the portion near the valve stem portion 11 over the flared slope portion 12. As a result, an angle Θ1 formed by the surface 20s of the coating layer 20A and the axis CL of the valve stem portion 11 is larger than an angle Θ2 of the flared slope portion 12 excluding the uneven portion 14A relative to the axis CL of the valve stem portion 11.

[0035]

In this way, in this embodiment, the slope angle Θ1 of the surface 20s of the coating layer 20A is formed larger than the slope angle Θ2 of the flared slope portion 12. Therefore, a fluid such as engine oil which is eventually transformed to deposits is difficult to stay on the coat layer 20A, as compared with a case where the slope angle of the coating layer which is formed to level the unevenness at the uneven portion 14A is smaller than the slope angle of the flared slope portion 12. Therefore, it is possible to further reduce the accumulation of deposits.

[0036] (Third Embodiment)

Fig. 4 is an enlarged sectional view of a main part of an intake valve according to a third embodiment. An intake valve 10B of the third embodiment differs from the intake valve 10 of the first embodiment in configuration of a flared slope portion 12B and a coating layer 20B. The remaining features of the intake valve 10B of the third embodiment are similar to those of the intake valve 10 of the first embodiment, and hence, in Fig. 4, like reference numerals are given to like constituent elements to those of the first embodiment shown in Fig. 1 or 2.

[0037]

As shown in Fig. 4, a flared slope portion 12B of this embodiment is formed so that an overall surface excluding the uneven portion 14 is formed into a concavely curved surface expanding toward a distal end face of the valve head 15. In this embodiment, similar to the first embodiment, the oil-repellent coating layer 20B is formed on the flared slope portion 12B including the uneven portion 14 and a part of a surface of the valve stem portion 11 which connects to the flared slope portion 12B. The coating layer 20B is formed to level unevenness at the uneven portion 14. The coating layer 20B has a portion covering the uneven portion 14 where increases in thickness to curve a surface of the coating layer 20B. The coating layer 20B has the thickness at a first boundary portion 14a of the uneven portion 14 which is good enough for the coating layer 20B to fdl or level the unevenness at the uneven portion 14. The coating layer 20B is formed so that a boundary with a valve seal portion 13 becomes almost flat at the second boundary portion 14b. Namely, a surface 20s of the coating layer 20B is formed into a curve protruding differently in two directions, and is made up of a curve extending along the curved surface of the flared slope portion 12B, and a curve extending along an outline of the valve seal portion 13. The curve of the surface 20s of the coating layer 20B which extends along the curved surface of the flared slope portion 12B may be formed so that an angle of the curve relative to the axis CL of the valve stem portion 11 is larger than an angle of the curved surface of the flared slope portion 12B relative to the axis CL of the valve stem portion 11.

[0038]

In this way, in this embodiment, the slope angle of the coating layer 20B which levels the unevenness at the uneven portion 14 of the flared slope portion 12B relative to the axis CL of the valve stem portion 11 is made larger. Therefore, a fluid such as engine oil which is eventually transformed to deposits is difficult to stay on the coating layer 20B. Therefore, it is possible to further reduce the accumulation of deposits.

[0039]

The invention is not limited to the embodiments that have been described heretofore and hence can be modified or improved as required. For example, the configuration of the uneven portions 14, 14A shown in Figs. 2 to 4 is in the step-like configuration. However, the invention can also be applied to forms where the coating layers 20, 20A, 20B are formed to level uneven portions of various configurations other than the step-like configuration.

Description of Reference Numerals and Characters [0040]

Internal combustion engine la Cylinder head

Intake port

2m Inlet

2s Inlet seal portion

Stem guide

Combustion chamber

10, 10A, 10B Intake valve

Valve stem portion

11s Non-sliding portion

12, 12B Flared slope portion

Valve seal portion

14, 14A Uneven portion
14a	First boundary portion
14b	Second boundary portion
14c	Third boundary portion
14d	Fourth boundary portion
14e, 14f, 14g Flat surface portion
20, 20A, 20B Coating layer
20s	Surface of coating layer
CF	Axis

Claims

1. An intake valve of an internal combustion engine, which is provided at an inlet of a combustion chamber of the internal combustion engine to open and close a communication between an intake port and the combustion chamber, comprising:

an uneven portion formed on a flared slope portion having a slope which gradually expands from a valve stem portion for reciprocating in an axial direction toward a valve seal portion for contacting with an inlet seal portion of the combustion chamber, and in which a slope angle of the flared slope portion changes at the uneven portion, wherein an oil-repellent coating layer is formed on at least part of the flared slope portion including the uneven portion to level unevenness at the uneven portion.

2. The intake valve of the internal combustion engine according to claim 1, wherein an angle formed by a surface of the coating layer and an axis of the valve stem portion is larger than an angle of the flared slope portion excluding the uneven portion relative to the valve stem portion.

3. The intake valve of the internal combustion engine according to claim 1 or 2, wherein the coating layer has a portion covering the uneven portion where increases in thickness to curve a surface of the coating layer.

4.

The intake valve of the internal combustion engine according to anyone of claims 1 to 3, wherein the coating layer is formed on the flared slope portion and a part of a surface of the valve stem portion which connects to the flared slope portion.

5. The intake valve of the internal combustion engine according to anyone of claims 1 to 4, wherein the coating layer is a fluorine coating layer.

6. The intake valve of the internal combustion engine according to anyone of claims 1 to 5, wherein the internal combustion engine is a gaseous fuel engine.

Intellectual

Property

Office

Application No: GB1721992.4