JP2008274873A - Intake-exhaust valve - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an intake-exhaust valve capable of efficiently conducting heat to a shaft part from a heat conduction medium passing through into the shaft part. <P>SOLUTION: This intake-exhaust valve has a valve body 46 having a shaft part 46a and a shade part 46b arranged on one end of the shaft part 46a, forming a hollow part 45 inside the shaft part 46a and the shade part 46b and sealing the heat conduction medium (sodium) in the hollow part 45, and a substantially bar-shaped flow passage forming member 54 arranged inside the hollow part 45 and setting the axial direction of the shaft part 46a in the longitudinal direction. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an intake / exhaust valve, and more particularly to an intake / exhaust valve having a hollow portion in which a heat conduction medium is enclosed.

  Generally, a cylinder head of an internal combustion engine is formed with a combustion chamber, an intake port for supplying gas to the combustion chamber, an exhaust port for discharging gas in the combustion chamber, and the like. Is opened and closed by each of an intake valve and an exhaust valve (hereinafter collectively referred to as “intake and exhaust valves”). The intake / exhaust valve has a shaft portion (stem portion) and an umbrella portion provided at one end portion of the stem portion, and the umbrella portion faces the combustion chamber. For this reason, when fuel burns in the combustion chamber, the heat generated at that time is easily transmitted to the umbrella portion of the intake / exhaust valve. If the temperature of the valve umbrella rises excessively under the influence of this heat, for example, the combustion state deteriorates, and abnormal combustion such as knocking and pre-ignition is induced, leading to a decrease in thermal efficiency and a decrease in output. is there. In particular, recent internal combustion engines have improved output compared to conventional internal combustion engines, and accordingly, the amount of heat generated has also increased.

  Therefore, in recent years, in order to avoid the influence of the heat, a valve guide and an oil seal that are arranged in contact with or in proximity to a valve seat that contacts the umbrella part, or an intake / exhaust valve, the heat transmitted to the umbrella part. The technique of radiating heat to the cooling water existing in the cylinder head is employed. Recently, a hollow part that encloses the cooling medium is formed inside the valve, and the cooling medium is splattered in the hollow part by the opening and closing operation of the valve, facilitating the transfer of heat from the umbrella part side to the stem part side. A technique (hollow valve technology) has been proposed. Furthermore, the technique which improved this hollow valve technique is disclosed by patent documents 1-4.

  Among these, Patent Literature 1 discloses a technique for appropriately guiding a cooling medium in order to reliably transfer heat from the umbrella side to the stem side, and Patent Literature 2 discloses a valve shaft portion (stem portion). ) Discloses a technique in which a capillary structure is provided in the hollow portion of the inside to distribute sodium evenly. Patent Document 3 discloses a technique in which a partition member having a cross-shaped cross section is provided in the internal space of a valve (valve) in order to form a cooling medium flow path inside the valve (valve). Discloses a technique in which naphthalene is used as a cooling medium, and a mesh-like wick is provided inside the stem portion and the umbrella portion so that naphthalene condensed on the shaft portion side is returned to the umbrella portion side by capillary action.

JP 2006-97499 A JP-A-5-141214 JP 2000-87708 A JP-A-2005-48635

  In the above hollow valve technology, since the heat is transferred from the cooling medium to the shaft portion by heat conduction, the cooling medium that passes near the center of the shaft portion is in contact with the inner peripheral surface of the shaft portion. It is conceivable that heat is harder to transfer than the medium (in other words, variation in heat transfer efficiency according to the passage position of the cooling medium in the shaft portion occurs). In other words, in order to achieve the cooling performance required for the hollow valve as the output of the internal combustion engine increases in the future, the variation in the heat transfer efficiency is suppressed as much as possible, and the heat from the entire cooling medium passing through the shaft portion is efficiently increased. Therefore, it is expected that the technology to transmit to the shaft part will be required.

  However, in the above Patent Documents 1 to 4, although there is a disclosure about a technique for effectively supplying the cooling medium from the umbrella side to the shaft side, the variation in the heat transfer efficiency according to the passing position of the cooling medium in the shaft, And the reduction of the heat conduction efficiency due to this is not taken into consideration.

  Therefore, the present invention has been made in view of the above problems, and an object thereof is to provide an intake / exhaust valve capable of efficiently conducting heat conduction from a heat conduction medium passing through the shaft portion to the shaft portion. .

  In order to solve the above-described problems, the present invention includes a shaft portion and an umbrella portion provided at one end of the shaft portion, and a hollow portion is formed inside the shaft portion and the umbrella portion. An intake / exhaust valve main body in which a heat conduction medium is sealed in a portion, and a substantially rod-shaped rod-shaped member provided in the hollow portion and having the axial direction of the shaft portion as a longitudinal direction.

  According to this, since the substantially rod-shaped rod-shaped member is provided inside the hollow portion formed in the intake / exhaust valve main body, the heat conduction medium passes between the rod-shaped member outer circumferential surface and the shaft portion inner circumferential surface. Therefore, compared with the case where a rod-shaped member is not provided, the ratio of the heat conductive medium in contact with the inner peripheral surface of the shaft portion with respect to the heat conductive medium passing through the shaft portion can be improved. Thereby, it is possible to efficiently conduct heat conduction from the heat conduction medium passing through the shaft portion to the shaft portion.

  In this case, a substantially constant clearance can be formed between the outer peripheral surface of the rod-shaped member and the inner peripheral surface of the shaft portion.

  In this case, one end portion of the rod-shaped member has a shape that follows at least a portion of the inner peripheral surface of the umbrella portion, and between the one end portion and at least a portion of the inner peripheral surface of the umbrella portion. A predetermined clearance may be formed. Further, the rod-shaped member may have a specific gravity lower than that of the intake / exhaust valve main body. In such a case, it is possible to reduce the weight of the entire intake / exhaust valve rather than processing the intake / exhaust valve main body to directly form the flow path of the heat conduction medium in the shaft portion.

  In the intake / exhaust valve according to the present invention, the rod-shaped member is formed of a flexible member that is curved as the intake / exhaust valve main body moves, and a part of the rod-shaped member is a part of the intake / exhaust valve main body. It can be fixed to. In such a case, the bar-shaped member made of a flexible member is bent as the intake / exhaust valve body moves, thereby stirring the heat transfer medium passing through the shaft portion. As a result, the ratio of the heat conduction medium contacting the shaft portion is higher than that in the case where no rod-shaped member is provided, so that heat conduction from the heat conduction medium passing through the shaft portion to the shaft portion can be performed efficiently. .

  In this case, at least a part of the rod-shaped member may have a flat plate shape. In such a case, stirring of the heat conduction medium by the rod-shaped member is promoted, and heat conduction from the heat conduction medium to the shaft portion can be performed more efficiently.

  ADVANTAGE OF THE INVENTION According to this invention, the intake / exhaust valve which can perform efficiently the heat conduction to the axial part from the heat conductive medium which passes in the inside of an axial part can be provided.

<< First Embodiment >>
Hereinafter, a first embodiment of the present invention will be described in detail with reference to FIGS. 1 and 2.

  FIG. 1 shows a partial configuration diagram of a cylinder head 12 in an internal combustion engine. As shown in FIG. 1, inside the cylinder head 12, there are a combustion chamber 22 and an exhaust port 24 that is in communication with the combustion chamber 22 and exhausts the gas burned in the combustion chamber 22. Is formed. Further, the cylinder head 12 is provided with an exhaust valve mechanism 30 for bringing the exhaust port 24 and the combustion chamber 22 into communication or non-communication. Although not shown, the cylinder head 12 is in communication with the combustion chamber 22, and an intake port for introducing exhaust gas into the combustion chamber 22 is also formed. Is provided with an intake valve mechanism for bringing the intake port and the combustion chamber 22 into communication or non-communication.

  The exhaust valve mechanism 30 is a direct acting valve mechanism, and includes an exhaust valve 32 that can reciprocate vertically in FIG. 1, a valve guide 34 that supports the exhaust valve 32 in a reciprocating manner, and a valve guide. 34, an oil seal 36 fixed to 34, a valve spring 38 formed of a compression coil spring in which the exhaust valve 32 is inserted, and a cam that contacts the upper end of the exhaust valve 32 and rotates about the rotation shaft of the cam shaft 42. 44. Among these, the lower end portions of the valve guide 34, the oil seal 36, and the valve spring 38 are fixed to the cylinder head 12 side. A valve seat 58 is provided at the end of the exhaust port 24 on the combustion chamber 22 side. The lower end side of the valve seat 58 is always in contact with the exhaust valve 32 when the exhaust valve 32 is in the state shown in FIG.

  As shown in FIG. 2, the exhaust valve 32 includes a valve body 46 having a shaft portion 46a having a cylindrical shape and a funnel-shaped umbrella portion 46b provided at a lower end portion of the shaft portion 46a, and a shaft portion. The upper cap part 48 which closes the opening of the upper end part of 46a, the lower cap part 52 which obstruct | occludes the opening of the lower end part of the umbrella part 46b, and these valve bodies 46, the upper cap part 48, and the lower cap part 52 are comprised. And a flow path forming member 54 as a rod-shaped member provided in the vicinity of the lower end portion in the internal space (hollow portion) 45. The valve body 46 is made of, for example, 21-4N steel (SUH35). Further, the valve main body 46 and each of the upper cap portion 48 and the lower cap portion 52 are joined by a joining technique such as laser welding or brazing. Further, sodium (Na) as a heat conduction medium is sealed in the internal space 45 (see FIG. 1). This sodium is in a liquid state at least during operation of the internal combustion engine, and its volume is, for example, about 50 to 70% of the volume of the internal space 45.

  Note that the heat conduction medium is not limited to sodium, and other metals (potassium (K) or the like) that are melted by heat to become a liquid may be employed. Moreover, it is good also as employ | adopting the ceramics and metal fine powder which are not fuse | melted with heat, such as aluminum nitride (AlN).

  The flow path forming member 54 is made of a member having a specific gravity lower than that of the valve main body 46 (for example, titanium), and has a shape that is slightly smaller than the space in the area A shown in FIG. ing. Although not shown in FIG. 2, the flow path forming member 54 is fixed to a part of the valve body 46 by welding or the like. A predetermined clearance 54a is formed between the outer peripheral surface of the flow path forming member 54 and the inner peripheral surface of the substantially lower half portion of the shaft portion 46a and the inner peripheral surface of the substantially upper half portion of the umbrella portion 46b. Therefore, when sodium moves between the lower space and the upper space of the flow path forming member 54, it passes through the clearance 54a.

  Returning to FIG. 1, the valve guide 34 is a substantially cylindrical member made of a material (for example, aluminum) having a higher thermal conductivity than the exhaust valve 32, and is inserted into a guide hole 34 a formed along the axis thereof. On the other hand, the exhaust valve 32 (shaft portion 46a) is inserted. A predetermined clearance is formed between the inner peripheral surface of the valve guide 34 and the outer peripheral surface of the shaft portion 46a, and the valve guide 34 restricts movement of the exhaust valve 32 in a direction other than the axial direction (longitudinal direction). Has been. In the present embodiment, it is assumed that the relationship between the diameter of the guide hole 34a and the diameter of the shaft portion 46a is set so that this clearance is optimal at the end of warm-up of the internal combustion engine.

  The oil seal 36 is a member for preventing oil that lubricates the inside of the cylinder head 12 from flowing through the exhaust valve 32 and flowing into the combustion chamber 22, and has an upper portion having substantially the same diameter as the shaft portion 46 a. A hole 36a is formed. A minute clearance is formed between the hole 36a of the oil seal 36 and the exhaust valve 32 (shaft portion 46a), and a small amount of oil is supplied to the clearance, whereby the oil seal It is possible to lubricate the exhaust valve 32 with respect to 36.

  The valve spring 38 is provided in a state in which an upper seat 64 provided via a valve cotter 62 and a lower seat 66 provided in a part of the cylinder head 12 are connected in the vicinity of the upper end portion of the exhaust valve 32 (shaft portion 46a). Thus, an upward biasing force is always applied to the exhaust valve 32.

  The cam 44 is rotationally driven via the cam shaft 42 by a rotation drive mechanism (not shown). The rotation of the cam 44 applies a force (downward force) against the urging force of the valve spring 38 to the upper end portion (upper cap portion 48) of the exhaust valve 32, and the downward force generated by the cam 44 and the valve The exhaust valve 32 moves up and down by the balance with the upward force by the spring 38. In the present embodiment, since the center of the central axis AX of the exhaust valve 32 (vertical direction in the drawing) and the center of the cam width (width in the direction perpendicular to the drawing) are offset with respect to the direction orthogonal to the drawing, It moves up and down while rotating around the central axis AX. Therefore, the position of the umbrella portion 46b of the exhaust valve 32 in contact with the valve seat 58 is changed according to the rotation of the cam.

  In the exhaust valve mechanism 30 configured as described above, when the exhaust valve 32 is in the state of FIG. 1, the exhaust port 24 and the combustion chamber 22 are set in a non-communication state (closed state). Further, as the cam 44 rotates, the exhaust valve 32 moves downward from the state shown in FIG. 1, so that the exhaust port 24 and the combustion chamber 22 are set in a communication state (open state). In the present embodiment, the exhaust valve 32 is reciprocated up and down (and rotated around the axis) so that the closed state and the open state are switched at a constant cycle. The internal sodium is agitated (shaking). In this case, sodium moves between the upper space and the lower space of the flow path forming member 54 via the clearance 54a. Therefore, when the heat generated in the combustion chamber 22 is conducted to the lower end surface (the lower surface of the lower cap portion 52) of the exhaust valve 32 facing the combustion chamber 22, the temperature of sodium is caused by the heat of the lower cap portion 52. However, the sodium moves while transferring heat to the shaft portion 46a during the stirring (shaking). In this embodiment, since sodium passes through the clearance 54a, the inner peripheral surface of the shaft portion 46a out of sodium passing through the shaft portion 46a as compared with the case where the flow path forming member 54 is not provided. The ratio of sodium in contact with can be increased. Thereby, it is possible to efficiently conduct heat conduction between sodium and the shaft portion 46a. Since the valve guide 34 made of a material having a higher thermal conductivity than the shaft portion 46a is close to the shaft portion 46a whose temperature is increased in this way, the heat of the shaft portion 46a is transmitted to the valve guide 34, The heat of the shaft portion 46a is radiated to the valve guide 34.

  As described above in detail, according to the exhaust valve 32 of the present embodiment, the predetermined clearance 54a is formed between the outer peripheral surface of the flow path forming member 54 and the inner peripheral surface of the shaft portion 46a, and the clearance 54a Since sodium flows through the clearance 54a, the rate of sodium contacting the inner peripheral surface of the shaft portion 46a is higher than when the flow path forming member 54 is not provided. Thereby, it is possible to efficiently conduct heat conduction from sodium passing through the shaft portion to the shaft portion 46a.

  Moreover, in this embodiment, since heat can be efficiently transmitted to the shaft portion 46a, the exhaust valve 32 can be efficiently cooled. Thereby, since the combustion state of the internal combustion engine becomes good, it is possible to suppress abnormal combustion such as knocking and pre-ignition, and to improve thermal efficiency and output.

  In the first embodiment, the case where the intake / exhaust valve of the present invention is applied to the exhaust valve 32 has been described. However, the present invention is not limited to this, and the intake / exhaust valve of the present invention is not illustrated. It is good also as applying to a valve.

  In the first embodiment, the case where the flow path forming member 54 has a shape that is slightly smaller than the space in the region A (see FIG. 2) of the internal space 45 has been described. However, it is possible to employ various shapes of flow path forming members. For example, as shown in FIG. 3, a flow path forming member 54 ′ having a substantially cylindrical shape can be employed. In this case, sodium existing in the space below the flow path forming member 54 ′ with respect to the clearance 54a ′ formed between the outer peripheral surface of the flow path forming member 54 ′ and the inner peripheral surface of the shaft portion 46a. Since it becomes easy to flow in, it is possible to efficiently conduct heat from sodium to the shaft portion 46a.

  In the above embodiment, the flow path forming member 54 has been described as having a lower specific gravity than the exhaust valve 32. However, from the viewpoint of improving the rate at which sodium contacts the inner peripheral surface of the shaft, Any material may be adopted as the material of the path forming member 54.

<< Second Embodiment >>
Next, a second embodiment of the present invention will be described with reference to FIGS. The second embodiment is characterized in that a stirring member 154 is provided as a rod-like member in place of the flow path forming member 54 (or 54 ′) provided in the exhaust valve 32 in the first embodiment. have. Accordingly, in the following description, the same or equivalent components as those in the first embodiment described above are denoted by the same reference numerals and the description thereof is omitted.

  FIG. 4 is a cross-sectional view of the exhaust valve 132 according to the second embodiment, and FIG. 5 is a perspective view showing a state in which the exhaust valve 132 is partly cross-sectioned. As shown in FIGS. 4 and 5, the stirring member 154 provided in the valve body 46 has a substantially rod-like shape, and its upper end is fixed to the center of the lower surface of the upper cap portion 48. Yes. The stirring member 154 is made of a flexible member made of steel, for example, and the lower end portion is curved as the exhaust valve 32 moves.

  In the exhaust valve 132 configured as described above, when the exhaust valve 132 is reciprocated up and down (and rotated around the axis) in accordance with the rotation of the cam 44, as in the first embodiment, The sodium in the internal space 45 is agitated (shaking) with the movement, but in this embodiment, the lower end of the agitating member 154 is curved with the movement of the exhaust valve 132, so that the agitation of sodium is further increased. Promoted. Thereby, compared with the case where the stirring member 154 is not provided, the ratio of sodium that contacts the inner peripheral surface of the shaft portion 46a to the entire sodium passing through the shaft portion 46a can be increased, so sodium and the shaft portion 46a. It is possible to efficiently conduct heat between the two.

  As described above, according to the exhaust valve 132 of the second embodiment, the stirring member 154 is bent as the exhaust valve 132 moves, so that stirring of sodium is further promoted. Thereby, compared with the case where the stirring member 154 is not provided, the ratio of sodium that contacts the inner peripheral surface of the shaft portion 46a to the entire sodium passing through the shaft portion 46a can be increased. It is possible to efficiently conduct heat conduction between the two.

  In the second embodiment, since heat can be efficiently transmitted to the shaft portion 46a, the exhaust valve 32 can be efficiently cooled. Thereby, since the combustion state of the internal combustion engine becomes good, it is possible to suppress abnormal combustion such as knocking and pre-ignition, thereby improving the thermal efficiency and the output.

  In the second embodiment, the case where the intake / exhaust valve of the present invention is adopted as an exhaust valve has been described. However, as in the first embodiment, it can also be adopted as an intake valve.

  In the second embodiment, the case where the stirring member 154 and the upper cap portion 48 are configured as separate members has been described. However, the present invention is not limited to this, and the stirring member 154 and the upper cap portion 48 are combined into one piece. It is good also as comprising integrally with a member.

  In the second embodiment, the case where the stirring member 154 is fixed to the upper cap portion 48 has been described. However, the present invention is not limited to this, and the stirring member 154 may be fixed to the inner peripheral surface of the shaft portion 46a of the valve body 46.

  Moreover, in the said 2nd Embodiment, although the case where the stirring member 154 consisted of a substantially rod-shaped member was demonstrated, it is not restricted to this, For example, as FIG.6 and FIG.7 shows, flat shape is shown in the lower end part. It is also possible to employ a stirring member 154 ′ having a portion 154a. The flat plate-like portion 154a is formed by press molding of the lower end portion of the stirring member 154 '. By adopting such a stirring member 154 ′, the contact area between the lower end portion (flat plate portion 154a) of the stirring member 154 ′ and sodium can be increased, so that the stirring efficiency of sodium can be improved. It becomes. The stirring member is not limited to the shape shown in FIGS. 6 and 7, and various shapes may be employed from the viewpoint of improving the stirring efficiency.

  The above-described embodiment is a preferred embodiment of the present invention. However, the present invention is not limited to this, and various modifications can be made without departing from the scope of the present invention.

It is a partial block diagram of the cylinder head of the internal combustion engine including the exhaust valve of the first embodiment. It is sectional drawing which takes out and shows the exhaust valve of FIG. It is sectional drawing which shows the modification of the exhaust valve of 1st Embodiment. It is a figure showing a section of an exhaust valve concerning a 2nd embodiment. It is a perspective view which shows a partial cross section of the exhaust valve according to the second embodiment. It is sectional drawing which shows the modification of the exhaust valve of 2nd Embodiment. FIG. 7 is a perspective view showing a partial cross section of the exhaust valve of FIG. 6.

Explanation of symbols

32 Exhaust valve 45 Internal space 46 Valve body 46a Shaft portion 46b Umbrella portion 54 Flow path forming member 54a Clearance 154 Stirring member

Claims (6)

An intake / exhaust valve having a shaft portion and an umbrella portion provided at one end of the shaft portion, a hollow portion is formed in the shaft portion and the umbrella portion, and a heat conduction medium is enclosed in the hollow portion The body,
An intake / exhaust valve provided with a substantially rod-shaped rod-like member provided in the hollow portion and having the axial direction of the shaft portion as a longitudinal direction. The intake / exhaust valve according to claim 1, wherein a substantially constant clearance is formed between an outer peripheral surface of the rod-shaped member and an inner peripheral surface of the shaft portion. One end portion of the rod-shaped member has a shape that follows at least a portion of the inner peripheral surface of the umbrella portion, and a predetermined clearance is provided between the one end portion and at least a portion of the inner peripheral surface of the umbrella portion. The intake / exhaust valve according to claim 2, wherein the intake / exhaust valve is formed. The intake / exhaust valve according to claim 2 or 3, wherein the rod-shaped member has a specific gravity lower than that of the intake / exhaust valve main body. The rod-shaped member is made of a flexible member that is curved with the movement of the intake / exhaust valve main body, and a part of the rod-shaped member is fixed to a part of the intake / exhaust valve main body. The intake / exhaust valve according to claim 1. The intake / exhaust valve according to claim 5, wherein at least a part of the rod-shaped member has a flat plate shape.

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