JP2018112087A - valve - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a valve that can prevent the difficulty of closing.SOLUTION: The present invention provides a valve that has: a valve element having a hollow part inside; an umbrella part provided at the tip of the valve element; a first portion that is provided between the base end side of the valve element and the umbrella part, and is thinner than the base end side of the valve element; and a second portion that is provided between the first portion of the valve element and the umbrella part and is thicker than the first portion. Such a valve can prevent the difficulty of closing.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a valve.

  In order to prevent carbon from sticking to the valve of the internal combustion engine, the valve may be provided with a carbon relief that is a portion having a small diameter (see, for example, Patent Document 1).

JP 2003-65456 A

  Since the heat capacity of the valve is determined by the cross-sectional area, the heat capacity decreases as the diameter decreases and the cross-sectional area decreases. Thereby, the temperature change of a valve | bulb becomes large and the amount of thermal expansion increases. As a result, the valve closing astringency occurs. Then, it aims at providing the valve | bulb which can suppress a closing astringency.

  The object is provided between a valve body having a hollow part therein, an umbrella part provided at a distal end of the valve body, a base end side of the valve body and the umbrella part, and the valve body Achieved by a valve comprising a first portion that is narrower than the base end side, and a second portion that is provided between the first portion and the umbrella portion of the valve body and is thicker than the first portion. it can.

  A valve capable of suppressing closing astringency can be provided.

FIG. 1 is a schematic view illustrating an internal combustion engine. FIG. 2 is a cross-sectional view illustrating a valve. FIG. 3A is a schematic diagram showing a cross-sectional area for each position of the valve. FIG. 3B is a diagram showing the amount of displacement of the component.

(First embodiment)
Hereinafter, the valve of the present embodiment will be described with reference to the drawings. FIG. 1 is a schematic view illustrating an internal combustion engine 100. The internal combustion engine 100 is a gasoline engine mounted on, for example, an automobile.

  As shown in FIG. 1, the cylinder head 10 of the internal combustion engine 100 is provided with an intake port 12 and an exhaust port 14. A valve 20 is provided in each of the intake port 12 and the exhaust port 14. The distal end portion of the valve 20 is located on the combustion chamber 11 side, and the proximal end side is in contact with one end of the rocker arm 18. The other end of the rocker arm 18 contacts the lash adjuster 16. The lash adjuster 16 is, for example, a hydraulic lash adjuster, and adjusts the clearance between the rocker arm 18 and the valve 20 by supporting the rocker arm 18. Two lash adjusters 16, rocker arms 18, and valves 20 are provided corresponding to the intake port 12 and the exhaust port 14, respectively.

  When the cam (not shown) presses the rocker arm 18, the valve 20 is pushed down, and the intake port 12 and the exhaust port 14 are opened. At this time, the lash adjuster 16 rises in the opposite direction to the valve 20. The depressed valve 20 is pushed up by, for example, the elastic force of a spring (not shown) provided in the cylinder head 10 and the intake port 12 and the exhaust port 14 are closed. At this time, the rocker arm 18 sinks in a direction opposite to the lift direction of the valve 20 (the direction of the arrow A1 in FIG. 1).

  FIG. 2 is a cross-sectional view illustrating the valve 20. As shown in FIG. 2, the valve body 21 of the valve 20 is provided with an umbrella portion 22, a shaft portion 23, a carbon relief 26, and a shaft portion 24 from the distal end side to the proximal end side. The intake port 12 and the exhaust port 14 shown in FIG. 1 are opened and closed by the umbrella part 22, and the umbrella part 22 enters the combustion chamber 11 when the valve is open. The shaft portion 24 slides in the cylinder head 10.

  As shown in FIG. 2, a carbon relief 26 and a shaft portion 23 (second portion) are provided between the umbrella portion 22 and the shaft portion 24 of the valve 20. The carbon relief 26 is located between the shaft portion 23 and the shaft portion 24, and has a small diameter portion 26 a (first portion) having a smaller diameter than the shaft portions 23 and 24. The lower end 26 b of the carbon relief 26 is a position where the diameter starts to be smaller than the shaft portion 23. The carbon relief 26 suppresses adhesion and accumulation of carbon on the valve 20.

  The change in the shape of the valve body 21 is smooth. That is, between the umbrella part 22 and the shaft part 23, between the shaft part 23 and the carbon relief 26, and between the carbon relief 26 and the shaft part 24 are connected by curves. In other words, a gentle slope is formed instead of a steep step between the umbrella portion 22 and the shaft portion 23, between the shaft portion 23 and the carbon relief 26, and between the carbon relief 26 and the shaft portion 24. .

  The valve body 21 of the valve 20 is made of metal such as heat-resistant steel (SUH: Steel Use Heat Resisting). A cylindrical hollow portion 28 is provided in the valve body 21 from the shaft portion 23 to the shaft portion 24. Metal sodium having a higher thermal conductivity than the valve body 21 is enclosed in the hollow portion 28. Thereby, the heat dissipation of the valve 20 is improved and the valve 20 is reduced in weight.

In the shaft portion 23, the thickness of the inner wall of the hollow portion 28 until the outer wall of the valve body 21 is T _1. In the small-diameter portion 26a, from the inner wall of the hollow portion 28 until the outer wall of the valve body 21 thickness is _{T 2, T 1} smaller. That is, the small diameter portion 26a is thin, and the shaft portion 23 is thick. Further, the valve body 21 becomes thicker toward the umbrella portion 22 from the small diameter portion 26a.

_{D 1} the diameter of the valve head 22, the diameter of the shaft portion 23 _{D 2,} diameter _{D 3} of the small-diameter portion 26a, diameter _{D 4} of the shaft portion 24, the diameter of the hollow portion 28 and _{D 5.} Umbrella portion 22 is a large portion of most diameter of the valve body 21, _{D 1} is greater than either of _D 2 to D _5. Small-diameter portion 26a is a small portion of most diameter of the valve body 21, _{D 3} is _D 1, _{D 2,} and _D is smaller than _4. The diameter _{D 5} of the hollow portion 28 is smaller than the diameter _{D 3} of the small-diameter portion 26a. May be equal to the diameter D ₂ and the diameter D ₄ of the shaft portion 24 of the shaft portion 23 may be different. A length L ₁ from the lower end of the hollow portion 28 to the lower surface of the bulb 20 is larger than the diameter D ₅ of the hollow portion 28.

Sectional area _{S 1} of the shaft portion 23 is ^{_{π (D 2/2) 2}} , the cross-sectional area _{S 2} of the small diameter portion 26a is ^{_{π (D 3/2) 2}} . Sectional area _{S 1} of the shaft portion 23 is larger than the cross-sectional area _{S 2} of the small diameter portion 26a, for example, it is more than twice.

FIG. 3A is a schematic diagram showing a cross-sectional area for each position of the valve 20. The horizontal axis indicates the position, and the vertical axis indicates the cross-sectional area. As shown in FIG. 3A, the cross-sectional area decreases from the umbrella portion 22 to the small diameter portion 26a. Sectional area of the lower end 26b is equal to the cross-sectional area _{S 1} of the shaft portion 23, the cross-sectional area _{S 2} of the small diameter portion 26a is less than half the _{S 1.} The cross-sectional area _{S 3 (= π (D 1} /2) 2) of the umbrella portion 22 is 10 times the cross-sectional area _{S 2} of the small diameter portion 26a.

  FIG. 3B is a diagram showing the amount of displacement of the component. The horizontal axis represents the elapsed time from the start of the internal combustion engine 100 (engine), and the vertical axis represents the amount of displacement. The black circles in the figure indicate the amount of displacement of the valve 20 in the first embodiment, and the white circles indicate the amount of displacement of the valve 20 in each comparative example. The amount of displacement of the valve 20 is the amount of thermal expansion in the extending direction of the valve 20 due to temperature change. The comparative example is an example in which the shaft portion 23 has the same diameter as the small diameter portion 26a. In addition, the solid line in the figure indicates the amount of sinking of the lash adjuster 16 when the valve is closed.

  As shown in FIG. 3 (b), the amount of displacement of the valve increases from the start and approaches a constant value. The displacement amount in the first embodiment is smaller than that in the comparative example. In the period indicated by the dashed ellipse in FIG. 3B, the displacement amount in the comparative example is larger than the sinking amount of the lash adjuster 16. That is, the valve thermally expands larger than the sinking amount of the lash adjuster 16. For this reason, even if the lift amount of the valve is zero, the intake port and the exhaust port cannot be closed, so-called closing agitation occurs. On the other hand, in the first embodiment indicated by black circles, the amount of elongation is smaller than the amount of sinking of the lash adjuster 16. That is, according to the first embodiment, the occurrence of closing astringency is suppressed.

  In the comparative example, since the diameter is small, the heat capacity of the valve is small. For this reason, the temperature of the valve easily rises due to the heat of the combustion chamber 11, and the amount of thermal expansion accompanying the temperature change also increases. In particular, the hollow portion makes the valve thin and the heat capacity is small. Further, in an internal combustion engine with low fuel consumption and high output, the combustion chamber 11 becomes high temperature, and the valve tip is also exposed to high temperature. Therefore, the amount of thermal expansion is increased in the comparative example. When closed astringency occurs, there is a risk that unburned gas will flow out of the combustion chamber, misfire, noise and vibration due to unstable combustion, and the like may occur. In particular, ignition may be retarded during cold start, and unburned gas may easily flow out or misfire. Further, since the combustion is not properly performed, the allowable rotational speed is reduced.

  On the other hand, according to the first embodiment, the shaft portion 23 that is thicker than the small diameter portion 26 a is provided between the small diameter portion 26 a and the umbrella portion 22. For this reason, the heat capacity of the valve 20 increases and the temperature change becomes small. As a result, as shown in FIG. 3B, the amount of thermal expansion (elongation) is also reduced, and the occurrence of closing astringency is suppressed. Therefore, outflow of unburned gas from the combustion chamber 11, misfire, and noise and vibration due to unstable combustion are also suppressed. Since combustion is appropriately performed, a decrease in the allowable rotational speed is suppressed.

  The valve 20 has a hollow portion 28. For this reason, it is thin in the vicinity of the small diameter portion 26a, and the heat capacity becomes small. On the other hand, since the valve body 21 is thick from the shaft portion 23 to the umbrella portion 22, the heat capacity increases and the thermal expansion amount decreases. Since the heat capacity of the umbrella portion 22 and the shaft portion 23 located on the distal end side of the valve 20 is large, even when the heat of the combustion chamber 11 is transmitted to the distal end side of the valve 20, the thermal expansion amount is small and the closing astringency is effective To be suppressed.

As shown in FIG. 3 (a), it is preferable that the cross-sectional area S ₁ of the shaft portion 23 is at least twice the cross-sectional area S ₂ of the small diameter portion 26a, or the like may be three times or more. Further, the length L ₁ from the lower end of the hollow portion 28 to the lower surface of the bulb 20 is preferably larger than the diameter D ₅ of the hollow portion 28. As a result, the heat capacity on the tip side of the valve 20 becomes larger, the amount of thermal expansion becomes smaller, and the closing astringency is effectively suppressed. In FIG. 2, the lower end of the hollow portion 28 is positioned in the vicinity of the umbrella portion 22, but may be positioned more proximally, for example, in the middle of the shaft portion 23. The length L ₁ is increased, the heat capacity is further increased.

  Metallic sodium is enclosed in the hollow portion 28. For this reason, the weight reduction of the valve | bulb 20 and the improvement of heat dissipation are possible. The substance sealed in the hollow portion 28 may be any material having a higher thermal conductivity than the material of the valve body 21 of the valve 20.

  The valve body 21 is provided with a carbon relief 26 including a small diameter portion 26a. For this reason, the accumulation of carbon on the valve 20 is suppressed, and the operation of the valve 20 is performed smoothly. Moreover, the change of the shape of the valve body 21 is smooth. That is, the umbrella portion 22 and the shaft portion 23, the shaft portion 23 and the carbon relief 26, and the carbon relief 26 and the shaft portion 24 are connected with a gentle curve instead of a steep step. For this reason, the concentration of stress caused by the temperature change is suppressed, and the breakage of the valve 20 is suppressed. Moreover, the weight of the valve 20 can be reduced as compared with the case where the step is formed.

  The first embodiment may be applied to at least one of the valve 20 (intake valve) on the intake port 12 side and the valve 20 (exhaust valve) on the exhaust port 14 side. By applying it to the valve 20 on the exhaust port 14 side through which high-temperature exhaust flows, it is possible to effectively suppress the closing astringency. Further, by applying to the valve 20 in both the intake port 12 and the exhaust port 14, it is possible to suppress the closing astringency in the intake process and the exhaust process.

  Although the preferred embodiments of the present invention have been described in detail above, the present invention is not limited to the specific embodiments, and various modifications and changes can be made within the scope of the gist of the present invention described in the claims. It can be changed.

DESCRIPTION OF SYMBOLS 10 Cylinder head 12 Intake port 14 Exhaust port 16 Rush adjuster 18 Rocker arm 20 Valve 21 Valve body 22 Umbrella part 23, 24 Shaft part 26 Carbon relief 26a Small diameter part 26b Lower end 28 Hollow part 100 Internal combustion engine

Claims (1)

A valve body having a hollow portion therein,
An umbrella provided at the tip of the valve body;
A first portion that is provided between the base end side of the valve body and the umbrella portion, and is thinner than the base end side of the valve body;
A valve provided between the first part of the valve body and the umbrella part and having a second part thicker than the first part.

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