JP6029742B2 - Hollow poppet valve - Google Patents

Description

  The present invention relates to a hollow poppet valve in which a coolant is charged in a hollow portion formed from an umbrella portion to a shaft portion of the poppet valve, and in particular, a hollow poppet in which a large-diameter hollow portion of the valve umbrella portion and a small-diameter hollow portion of the valve shaft portion communicate with each other. Regarding valves.

  In the following Patent Documents 1 and 2 and the like, a hollow portion is formed from the umbrella portion to the shaft portion of the poppet valve in which the umbrella portion is integrally formed at the shaft end portion, and the coolant has a higher thermal conductivity than the base material of the valve. A hollow poppet valve is described in which (for example, metallic sodium, melting point about 98 ° C.) is loaded into the hollow part together with an inert gas.

  Since the hollow portion of the valve extends from the inside of the umbrella portion into the shaft portion, and so much coolant can be loaded into the hollow portion, the thermal conductivity of the valve (hereinafter referred to as the heat extraction effect of the valve) can be improved. it can.

  That is, although the combustion chamber becomes hot due to the driving of the engine, if the temperature of the combustion chamber is too high, knocking occurs and a predetermined engine output cannot be obtained, leading to deterioration of fuel consumption (deterioration of engine performance). Therefore, as a method of actively conducting heat generated in the combustion chamber through the valve in order to lower the temperature of the combustion chamber (a method for increasing the heat-sucking effect of the valve), the coolant is hollowed together with the inert gas. Various hollow valves loaded in the box have been proposed.

WO2010 / 041337 JP2011-179328 2-12402

  In the conventional hollow poppet valve with refrigerant (Patent Documents 1 and 2), the communication portion between the disk-shaped large-diameter hollow portion in the umbrella portion and the linear small-diameter hollow portion in the shaft portion is a smooth curved region (the inner diameter gradually changes). However, when the valve is opened and closed (reciprocating in the axial direction of the valve), the coolant (liquid) is large together with the enclosed gas. It is considered that the diameter of the hollow portion can be smoothly moved between the small-diameter hollow portion and the small-diameter hollow portion, so that the heat drawing effect of the valve is improved.

  However, in the prior art (Patent Documents 1 and 2), since the coolant (liquid) can move smoothly between the large-diameter hollow portion and the small-diameter hollow portion in accordance with the opening / closing operation of the valve, the coolant (liquid) in the hollow portion Are moving in the axial direction in a state where the upper layer portion, middle layer portion, and lower layer portion are maintained in a vertical relationship without being stirred.

  For this reason, there is a problem that heat in the lower layer portion of the coolant close to the heat source is not positively transmitted to the middle layer portion and the upper layer portion of the coolant, and the heat drawing effect (thermal conductivity) is not sufficiently exhibited.

  On the other hand, in Patent Document 3, the small-diameter hollow portion in the valve shaft portion communicates perpendicularly to the ceiling surface of the disk-shaped (cylindrical) large-diameter hollow portion in the valve umbrella portion, and the valve reciprocates in the axial direction. Due to the inertial force acting on the coolant during operation, the coolant flows upward along the outer peripheral surface of the large-diameter hollow portion, and the coolant in the large-diameter hollow portion turns inward in the longitudinal direction. It is presumed that since the flow (hereinafter, this vertical swirl flow is called a tumble flow) is formed and the coolant is agitated, the heat-sucking effect of the valve is increased.

  However, in Patent Document 3, since the outer peripheral surface of the large-diameter hollow portion (the inner peripheral surface of the concave portion of the umbrella outer shell) is cylindrical, the large-diameter hollow portion generated when the valve reciprocates in the axial direction. The flow of the coolant upward along the outer peripheral surface is very weak.

  That is, the inventors have examined that, for example, during acceleration / deceleration or cornering of an automobile, the direction of the inertial force acting on the coolant in the hollow portion of the valve is different from the vertical direction. When the reciprocating operation is performed in the direction, the coolant flow does not necessarily occur upward over the entire outer periphery of the large-diameter hollow portion.

  Moreover, the rotational friction torque generated on the sliding contact surface between the valve shaft end portion to which the shaft load is transmitted and the shaft load transmission member (for example, a rocker arm in the rocker arm type valve mechanism, or a tappet in the direct acting type valve mechanism). Depending on the size of the valve, the valve may move up and down in the axial direction while rotating in the circumferential direction. In such a case, when the valve reciprocates in the axial direction, it follows the outer circumferential surface of the large-diameter hollow portion. Accordingly, a flow in the circumferential direction is also generated, and accordingly, the flow of the coolant upward is weakened along the outer peripheral surface of the large-diameter hollow portion.

  As described above, in Patent Document 3, when the valve reciprocates in the axial direction, the inner tumble flow is not always smoothly formed in the coolant in the large-diameter hollow portion, and the coolant is sufficiently stirred. Therefore, the heat-sucking effect of the valve cannot be greatly improved.

  Therefore, the inventor provided vertical ribs at equal intervals in the circumferential direction on the inner circumferential surface of the concave portion of the umbrella outer shell that defines the outer circumferential surface of the large-diameter hollow portion, and when the valve reciprocates in the axial direction, It was considered that the formation of an inner tumble flow was promoted in the coolant in the large-diameter hollow portion if the generation of the coolant flowing upward along the outer peripheral surface of the large-diameter hollow portion was promoted.

  The present invention has been made on the basis of the problems of the prior art described above and the knowledge of the inventor. The purpose of the present invention is to provide vertical ribs on the inner peripheral surface of the concave portion of the umbrella outer shell that defines the large-diameter hollow portion. By providing it and facilitating the generation of coolant flow upward from the bottom surface side of the large-diameter hollow portion along the outer peripheral surface, the formation of the inner tumble flow is promoted, and the heat drawing effect of the valve (heat conduction) It is an object of the present invention to provide a hollow poppet valve that can greatly improve the performance.

In order to achieve the object, in the hollow poppet valve according to the present invention (Claim 1), the hollow portion is formed from the umbrella portion of the poppet valve integrally formed at the shaft end portion to the shaft portion, In a hollow poppet valve in which a coolant is loaded with an inert gas in the hollow portion,
A disc-shaped large-diameter hollow portion is provided in the valve umbrella portion, and a linear small-diameter hollow portion provided in the valve shaft portion communicates perpendicularly to a ceiling surface of the disc-shaped large-diameter hollow portion. And, when the valve reciprocates in the axial direction, a hollow poppet valve in which a tumble flow around the central axis of the valve is formed at least in the coolant in the large-diameter hollow portion,
The large-diameter hollow portion is welded to the outer shell of the umbrella portion formed with a recess that defines the entire ceiling side of the large-diameter hollow portion, and the bottom surface of the large-diameter hollow portion is defined by welding to the opening side of the recess. Composed of caps,
Longitudinal ribs were provided at equal intervals in the circumferential direction on the inner circumferential surface of the umbrella outer shell.

  (Operation) When the valve shifts from the closed state to the open state (when the valve descends), as shown in FIG. 3 (a), the inertial force is directed upward in the coolant (liquid) in the hollow portion. Act on. And since the inertial force (upward) acting on the coolant in the central part of the large-diameter hollow part is larger than the inertial force acting on the coolant in the peripheral area of the large-diameter hollow part, the coolant in the large-diameter hollow part It tries to move to the small-diameter hollow part via. However, since the communication portion is formed with a bowl-shaped annular step portion, in other words, the ceiling surface of the large-diameter hollow portion (the opening peripheral edge of the small-diameter hollow portion in the large-diameter hollow portion) is in the central axis of the valve. On the other hand, since it is composed of a plane that is substantially orthogonal, the coolant cannot smoothly move to the small-diameter hollow portion like a conventional hollow valve in which the communicating portion is formed in a smooth shape.

  That is, an upward inertial force acts on the coolant in the large-diameter hollow portion, and as shown in FIG. 4 (a), the communication portion along the annular stepped portion (the ceiling surface of the large-diameter hollow portion). Flows F1 and F2 toward the center (radially inside) are generated. Then, the flows F2 heading toward the center (radially inner side) of the communication portion along the annular stepped portion collide with each other, and in the communication portion, the flow F3 toward the bottom surface side of the large-diameter hollow portion and the small-diameter hollow portion S2 An upward flow F4 is generated. In the communicating portion, the flow F3 toward the bottom surface side of the large-diameter hollow portion wraps around the bottom surface of the large-diameter hollow portion from the outside in the radial direction along the bottom surface of the large-diameter hollow portion, and again along the ceiling surface of the large-diameter hollow portion. Thus, the flows F1 and F2 are directed toward the center (radially inward) of the communication portion. On the other hand, in the communicating portion, the flows F4 and F5 directed upward of the small-diameter hollow portion are turbulent as shown in FIG.

  In this way, in the coolant in the large-diameter hollow portion, as shown by arrows F1 → F2 → F3 → F1, an inward tumble flow is formed around the central axis of the valve. Turbulence as shown by F4 and F5 occurs.

  On the other hand, when the valve transitions from the open state to the closed state (when the valve is raised), as shown in FIG. 3B, the inertial force acts downward on the coolant in the hollow portion. Since the inertial force (downward) acting on the coolant in the central portion of the large-diameter hollow portion is larger than the inertial force acting on the coolant in the peripheral region of the large-diameter hollow portion, as shown in FIG. In the coolant in the diameter hollow portion, a flow F6 directed radially outward from the center portion of the large diameter hollow portion along the bottom surface is generated, and at the same time, the flow toward the lower side through the communicating portion also in the small diameter hollow portion ( Turbulence) F7 occurs. The flow F6 along the bottom surface of the large-diameter hollow portion flows from the outside of the large-diameter hollow portion to the ceiling surface side to become a flow F8 along the ceiling surface of the large-diameter hollow portion S1, and the central portion of the large-diameter hollow portion , Merges with downward flows F6 and F7.

  That is, as shown by arrows F6 → F8 → F6, an inward vortex flow (hereinafter referred to as a tumble flow) is formed in the coolant in the large-diameter hollow portion, and the coolant in the small-diameter hollow portion is formed. , A turbulent flow as shown by an arrow F7 occurs.

  As described above, when the valve opens and closes, tumble flow and turbulent flow are also formed in the coolant in the large-diameter hollow portion of the valve, and the upper, middle, and lower layers of the coolant are actively stirred. Therefore, the heat pulling effect (thermal conductivity) of the valve is remarkably improved.

  As described above, when the valve reciprocates in the axial direction, the coolant in the hollow portion moves up and down in the hollow portion due to the inertial force that acts, and the coolant in the large-diameter hollow portion at that time has a large diameter. By generating a flow upward from the bottom surface side of the hollow portion along the outer peripheral surface, an inward tumble flow is formed around the central axis of the valve. Especially when the vehicle is accelerating / decelerating or cornering, inertia force acts on the coolant in the hollow part in a direction other than the vertical direction, or the shaft end and the shaft load to which the axial load is transmitted. Even when the valve moves up and down in the axial direction while rotating in the circumferential direction due to rotational friction torque generated on the sliding contact surface with the transmission member (for example, rocker arm or tappet), the valve reciprocates in the axial direction. Since the coolant that tries to move with the inertial force acting on the inner surface of the umbrella outer shell is restrained from moving in the circumferential direction by the vertical ribs provided on the inner peripheral surface of the umbrella outer shell, A coolant flowing upward along the outer peripheral surface is reliably generated.

  Furthermore, since the upward flow generated in the entire outer periphery of the large-diameter hollow portion is guided in the vertical direction by the vertical ribs toward the ceiling surface of the large-diameter hollow portion, the inner flow is in the entire periphery around the central axis of the valve. A tumble flow is formed.

  In addition, the vertical rib provided on the outer peripheral surface of the large-diameter hollow portion in the valve umbrella (the inner peripheral surface of the concave portion of the umbrella outer shell) increases the rigidity of the valve umbrella. ) Is increased in thickness to increase the volume of the large-diameter hollow portion (the amount of coolant loaded in the valve umbrella portion is increased), thereby increasing the heat transfer efficiency in the valve umbrella portion.

  In addition, the vertical rib provided on the outer peripheral surface of the large-diameter hollow portion in the valve umbrella portion (the inner peripheral surface of the concave portion of the umbrella outer shell) increases the contact area of the umbrella outer shell with the coolant, thereby increasing the valve umbrella portion. Increases heat transfer efficiency.

  In addition, in proportion to the number of vertical ribs provided on the outer peripheral surface of the large-diameter hollow portion in the valve umbrella portion (inner peripheral surface of the concave portion of the outer shell of the umbrella portion), the outer peripheral surface (umbrella outer shell) from the bottom side of the large-diameter hollow portion As the number of coolant flows guided upward along the inner peripheral surface of the concave portion of the recess increases, the rigidity of the valve umbrella increases, and the contact area with the coolant also increases. desirable.

  On the other hand, when there are too many vertical ribs, the interval between adjacent vertical ribs is narrow, leading upward from the bottom surface side of the large-diameter hollow portion along the outer peripheral surface (the inner peripheral surface of the concave portion of the umbrella outer shell). Since the flow path resistance of the coolant increases and the processing of the vertical ribs becomes troublesome, it is also a problem that there are too many, and it is desirable to provide them at 4 to 16 locations equally in the circumferential direction.

  According to a second aspect of the present invention, in the hollow poppet valve according to the first aspect, a vertical groove having an arc-shaped horizontal section sandwiched between the vertical ribs is continuously provided in the circumferential direction on the inner peripheral surface of the recess. did.

  (Operation) The vertical groove with the horizontal cross-section arc shape has a larger angle between the groove side surface and the groove bottom surface than the vertical groove with the U-shaped horizontal cross section, and the flow of the coolant upward in the vertical direction becomes smoother. .

  That is, the outer circumferential surface (recess of the concave portion of the umbrella outer shell) is formed from the bottom surface side of the large diameter hollow portion by the longitudinal grooves provided on the entire circumference of the outer peripheral surface of the large hollow portion (the inner peripheral surface of the concave portion of the umbrella outer shell). Since the coolant flow toward the upper side in the vertical direction along the inner peripheral surface is smoothly formed in the entire circumference of the large-diameter hollow portion, the stirring of the coolant in the large-diameter hollow portion by the tumble flow is further promoted. .

  According to a third aspect of the present invention, in the hollow poppet valve according to the first or second aspect, the large-diameter hollow portion is formed in a truncated cone shape having a tapered outer peripheral surface that substantially follows the outer shape of the valve umbrella portion.

  (Operation) Since the circular ceiling surface of the large-diameter hollow part (upper surface of the truncated cone) and the outer peripheral surface of the large-diameter hollow part (the outer peripheral surface of the truncated cone) form an obtuse angle, The coolant flow (F1, F2 in FIG. 4 (a) and F8 in FIG. 4 (b)) from the outside in the radial direction toward the communicating portion along the outer peripheral surface and ceiling surface of the large-diameter hollow portion is smooth. Therefore, a tumble flow is likely to be formed in the coolant in the large-diameter hollow portion.

  According to the hollow poppet valve according to the present invention (Claim 1), when the valve reciprocates in the axial direction, an upward flow is surely generated in the entire circumference of the large-diameter hollow portion, and the valve is around the central axis of the valve. An inward tumble flow is formed around the entire circumference and the stirring of the coolant in the large-diameter hollow portion is promoted, so that the heat-drawing effect (thermal conductivity) of the valve is improved and the performance of the engine is improved.

  In addition, by increasing the rigidity of the valve umbrella part, the valve umbrella part (umbrella outer shell) is thinned and the volume of the large-diameter hollow part (the amount of coolant loaded in the valve umbrella part) is increased. The heat transfer efficiency in the section is increased, and the heat-sucking effect of the valve can be further enhanced.

  In addition, the heat transfer efficiency in the valve umbrella is increased by increasing the contact area of the umbrella outer shell with the coolant, and the heat extraction effect of the valve can be further enhanced.

  According to the hollow poppet valve according to claim 2, when the valve reciprocates in the axial direction, the upward flow is smoothly generated in the entire circumference of the large-diameter hollow portion, and the inside of the large-diameter hollow portion due to the inner tumble flow Since the stirring of the coolant is further promoted, the heat extraction effect (thermal conductivity) of the valve is surely improved, and the performance of the engine is further improved.

  According to the hollow poppet valve of the third aspect, since the tumble flow is likely to occur in the coolant in the large-diameter hollow portion when the valve opens and closes, the heat drawing effect (thermal conductivity) of the valve is further improved. The engine performance is further improved.

It is a longitudinal cross-sectional view of the hollow poppet valve which is the 1st Example of this invention. (A) is a longitudinal cross-sectional view of an umbrella part outer shell, (b) is a bottom view of an umbrella part outer shell. It is a figure which shows the inertial force which acts on the coolant in the hollow part at the time of the same hollow poppet valve reciprocatingly, (a) shows the inertial force which acts on the coolant at the time of valve opening operation | movement (lowering operation | movement). Sectional drawing and (b) are sectional drawings which show the inertial force which acts on the coolant at the time of valve closing operation | movement (rise operation | movement). It is a figure which expands and shows the motion of the coolant in a hollow part when the hollow poppet valve opens and closes (reciprocates in an axial direction), and (a) is the coolant at the time of shifting from a valve closing state to a valve opening state FIG. 5B is a diagram illustrating the movement of the coolant when the valve is shifted from the open state to the closed state. FIG. 4 is a diagram showing a manufacturing process of the hollow poppet valve, where (a) shows a hot forging process for forging a shade which is an intermediate product of the valve, and (b) drills a hole corresponding to a small-diameter hollow part near the umbrella part. (C) shows a hole drilling process for drilling a hole corresponding to the small-diameter hollow portion near the shaft end, (d) shows an axial contact process for axially contacting the shaft end member, e) shows a coolant loading step of filling the small-diameter hollow portion with the coolant, and (f) shows a step of welding a cap to the inner periphery of the opening of the concave portion (large-diameter hollow portion) of the umbrella outer shell (large-diameter hollow portion) (Sealing process). It is a longitudinal cross-sectional view of the hollow poppet valve which is the 2nd Example of this invention. It is a bottom view (figure corresponding to Drawing 2 (b)) of the umbrella part outer shell of the valve. It is a longitudinal cross-sectional view of the hollow poppet valve which is the 3rd Example of this invention. The figure which shows the manufacturing process of the same hollow poppet valve, (a) shows the forging process which shape | molds an umbrella outer shell in an axial end part by upset forging (or extrusion forging), (b) is equivalent to a small diameter hollow part (C) shows a step of filling the small-diameter hollow portion with a coolant, and (d) shows a concave portion of the umbrella outer shell under an inert gas atmosphere. The process (large diameter hollow part sealing process) which welds a cap to the opening part of a large diameter hollow part is shown.

  Next, embodiments of the present invention will be described based on examples.

  1 to 5 show a hollow poppet valve for an internal combustion engine according to a first embodiment of the present invention.

  In these drawings, reference numeral 10 denotes a heat-resistant alloy in which an umbrella portion 14 is integrally formed on one end side of a shaft portion 12 that extends straight through an R-shaped fillet portion 13 that gradually increases in outer diameter. In the hollow poppet valve, a tapered face portion 16 is provided on the outer periphery of the umbrella portion 14.

  Specifically, a shaft-integrated shell (hereinafter simply referred to as a shell) 11 that is a valve intermediate product in which an umbrella outer shell 14a is integrally formed on one end side of a cylindrical shaft portion 12a, and a shaft contact with the shaft portion 12a. A hollow portion S is provided from the umbrella portion 14 to the shaft portion 12 by the shaft end member 12b and the disk-shaped cap 18 welded to the inner periphery 14c of the opening in the truncated cone-shaped recess 14b of the umbrella portion outer shell 14a. The hollow poppet valve 10 is configured, and the hollow portion S is loaded with a coolant 19 such as metallic sodium together with an inert gas such as argon gas.

  Although a larger amount of the coolant 19 is more excellent in the heat-drawing effect, a difference in heat-drawing effect is small if the amount is larger than a predetermined amount, so that cost-effectiveness (the more the coolant 19 is, the higher the cost). For example, an amount of about 1/2 to about 4/5 of the volume of the hollow portion S may be loaded.

  In FIG. 1, reference numeral 2 is a cylinder head, reference numeral 6 is an exhaust passage extending from the combustion chamber 4, and a tapered surface 8a on which the face portion 16 of the valve 10 can abut the peripheral edge of the exhaust passage 6 to the combustion chamber 4. An annular valve seat 8 is provided. Reference numeral 3 denotes a valve insertion hole provided in the cylinder head 2, and an inner peripheral surface of the valve insertion hole 3 is constituted by a valve guide 3 a with which the shaft portion 12 of the valve 10 is slidably contacted. Reference numeral 9 is a valve spring for urging the valve 10 in the valve closing direction, and reference numeral 12c is a cotter groove provided at the end of the valve shaft.

  The hollow portion S in the valve 10 includes a truncated cone-shaped large-diameter hollow portion S1 provided in the valve umbrella portion 14 and a linear (rod-shaped) small-diameter hollow portion S2 provided in the valve shaft portion 12. The circular ceiling surface of the large-diameter hollow portion S1 (the circular bottom surface of the truncated conical recess 14b of the umbrella outer shell 14a) 14b1 is orthogonal to the central axis L of the bulb 10. It consists of a plane.

  That is, the communicating portion P with the small-diameter hollow portion S2 in the large-diameter hollow portion S1 has a bowl-shaped annular step portion as viewed from the large-diameter hollow portion S1 instead of the smooth shape as in the prior art documents 1 and 2. 15 is formed, and the side (surface) 14b1 facing the large-diameter hollow portion S1 of the annular step portion 15 is configured by a plane orthogonal to the central axis L of the bulb 10. In other words, the bowl-shaped annular step portion 15 is formed by the opening peripheral edge portion (circular bottom surface of the truncated conical recess 14b of the umbrella outer shell 14a) 14b1 and the inner peripheral surface of the small diameter hollow portion S1. It is defined.

  For this reason, when the valve 10 is opened and closed, the coolant 19 in the large-diameter hollow portion S1 will be described in detail later, but arrows F1 → F2 → F3 in FIGS. 4 (a) and 4 (b); As shown in F6 → F8, an inner tumble flow is formed, and at the same time, the coolant 19 near the large-diameter hollow portion S1 in the small-diameter hollow portion S2 has a turbulent flow as shown by arrows F4, F5, and F7. Is generated, and the lower layer portion, the middle layer portion, and the upper layer portion of the coolant 19 in the hollow portion S are positively stirred, so that the heat drawing effect (thermal conductivity) in the valve 10 is greatly improved. ing.

  In particular, in this embodiment, the circular ceiling surface (circular bottom surface of the recess 14b) 14b1 of the large-diameter hollow portion S1 and the inclined outer peripheral surface (inclined inner peripheral surface) 14b2 form an obtuse angle, so that the valve 10 opens and closes. At the same time, the flow of the coolant 19 from the radially outer side of the large-diameter hollow portion S1 toward the communicating portion P along the inclined outer peripheral surface 14b2 and the ceiling surface 14b1 of the large-diameter hollow portion S1 (F1, F1 in FIG. 4A) Since the generation of F2 and F8) in FIG. 4B is smooth and the inner tumble flow formed in the coolant 19 in the large-diameter hollow portion S2 becomes active, the coolant 19 in the hollow portion S is activated. Therefore, the heat absorption effect (thermal conductivity) in the valve 10 is remarkably improved.

  Further, on the inner peripheral surface 14b2 of the concave portion 14b of the umbrella outer shell 14a constituting the outer peripheral surface of the large-diameter hollow portion S1, as shown in an enlarged view in FIG. The groove 20 is formed continuously. Then, when the valve 10 reciprocates in the axial direction, the longitudinal rib 21 defined by the longitudinal grooves 20 and 20 adjacent in the circumferential direction moves upward along the outer peripheral surface of the large-diameter hollow portion S1. The generation of the flow 19 is promoted to promote the formation of an inner tumble flow in the coolant 19 in the large-diameter hollow portion S1.

  That is, even when an inertial force in various directions acts on the coolant 19 in the hollow portion S, such as during acceleration / deceleration traveling or cornering traveling of an automobile, or the valve shaft end portion to which the axial load is transmitted While the valve 10 rotates in the circumferential direction due to rotational friction torque generated on the sliding contact surface with an axial load transmission member (for example, a rocker arm in a rocker arm type valve mechanism, a tappet in a direct acting valve mechanism) Even when the valve 10 moves up and down, the coolant 19 that tends to move with the inertial force that acts as the valve 10 reciprocates in the axial direction is provided on the inner peripheral surface 14b2 of the umbrella outer shell 14a. Since the movement in the circumferential direction is suppressed by the ribs 21, the flow of the coolant 19 from the bottom surface side of the large-diameter hollow portion S1 upward along the inclined outer peripheral surface 14b2 is reliably generated.

  Further, since the upward flow generated in the entire outer periphery of the large-diameter hollow portion S1 is smoothly guided in the vertical direction toward the ceiling surface 14b1 by the vertical groove 20 having an arc-shaped horizontal section, the central axis L of the valve 10 is obtained. An inner tumble flow is reliably formed on the entire circumference. As a result, the lower layer portion, middle layer portion, and upper layer portion of the coolant 19 in the large-diameter hollow portion S1 are more actively agitated, and the heat drawing effect (thermal conductivity) in the valve 10 is further greatly increased. It has been improved.

  The small-diameter hollow portion S2 in the valve shaft portion 12 is composed of a small-diameter hollow portion S21 having a relatively large inner diameter near the valve shaft end portion and a small-diameter hollow portion S22 having a relatively small inner diameter near the valve umbrella portion 14. Thus, an annular stepped portion 17 is formed between the small-diameter hollow portion S21 and the small-diameter hollow portion S22, and the coolant 19 is loaded up to a position beyond the stepped portion 17.

  Therefore, when the coolant 19 moves up and down the small-diameter hollow portion S2 by the inertial force that acts when the valve 10 is opened and closed, as indicated by arrows F9 and F10 in FIGS. 4 (a) and 4 (b). In addition, a turbulent flow is formed in the vicinity of the annular stepped portion 17, and the stirring of the coolant 19 in the small-diameter hollow portion S2 is promoted, so that the heat drawing effect (thermal conductivity) in the valve 10 is further improved. .

  Next, the movement of the coolant when the valve 10 opens and closes will be described in detail with reference to FIGS.

  When the valve 10 shifts from the closed state to the open state (when the valve 10 is lowered), the inertial force is upwardly applied to the coolant (liquid) 19 in the hollow portion S as shown in FIG. Act on. Since the inertial force (upward) acting on the coolant 19 in the central portion of the large-diameter hollow portion S1 is larger than the inertial force acting on the coolant 19 in the peripheral region of the large-diameter hollow portion S1, the inside of the large-diameter hollow portion S1 The coolant 19 tries to move to the small-diameter hollow portion S2 via the communication portion P. However, since the communication portion P is formed with the bowl-shaped annular step portion 15, the communication portion is formed in a smooth shape, and the small-diameter hollow portion S <b> 2 can be smoothly smooth like the conventional hollow valve shown in the prior art. Cannot move to the side.

  That is, an upward inertia force acts on the coolant 19 in the large-diameter hollow portion S1, and as shown in FIG. 4A, an annular step portion 15 (the ceiling surface of the large-diameter hollow portion S1). 14b1), flows F1 and F2 are generated toward the center (radially inside) of the communication portion P. In particular, the movement of the coolant 19 in the circumferential direction is suppressed by the longitudinal grooves 20 (vertical ribs 21) provided at equal intervals in the circumferential direction on the inner circumferential surface 14b2 of the recess 14b of the umbrella outer shell 14a. The flow F1 of the coolant 19 that flows upward along the outer peripheral surface from the bottom surface side of the large-diameter hollow portion S1 is reliably generated.

  Then, the flows F2 toward the center (radially inner side) of the communication portion P along the annular stepped portion 15 collide with each other, and in the communication portion P, the flow F3 toward the bottom surface side of the large-diameter hollow portion S1 and the small diameter A flow F4 directed upward of the hollow portion S2 is generated.

  In the communication portion P, the flow F3 toward the bottom surface side of the large-diameter hollow portion S1 is guided to the vertical groove 20 (vertical rib 21) from the outside in the radial direction along the bottom surface of the large-diameter hollow portion S1, and the large-diameter hollow portion S1. The air flows around the ceiling surface 14b1, and again becomes flows F1 and F2 toward the center (radially inner side) of the communication portion P along the ceiling surface 14b1 of the large-diameter hollow portion S1. On the other hand, in the communication portion P, the flows F4 and F5 directed upward of the small-diameter hollow portion S2 are turbulent as shown in FIG.

  Thus, when the valve 10 shifts from the closed state to the open state (when the valve 10 is lowered), the coolant 19 in the large-diameter hollow portion S1 has an arrow F1-> F2-> F3-> F1. As shown, an inward tumble flow is formed around the central axis L of the valve 10, and turbulent flow as shown by F4 and F5 occurs in the coolant 19 in the small-diameter hollow portion S2.

  Furthermore, when the valve 10 shifts from the closed state to the open state (when the valve 10 is lowered), the coolant 19 in the small diameter hollow portion S2 is subjected to an upward inertial force so that the small diameter hollow portion S2 As shown in FIG. 4A, when moving from the small-diameter hollow portion S22 near the valve umbrella portion 14 having a small inner diameter to the small-diameter hollow portion S21 near the valve shaft end portion having a large inner diameter. A turbulent flow F9 is generated downstream of the stepped portion 17 (above FIG. 4A).

  On the other hand, when the valve 10 transitions from the open state to the closed state (when the valve 10 is raised), as shown in FIG. 4B, the inertial force is applied downward to the coolant 19 in the hollow portion S. Act on. And since the inertia force (downward) which acts on the coolant 19 of large diameter hollow part S1 center part is larger than the inertial force which acts on the coolant 19 of large diameter hollow part S1 peripheral region, it shows in FIG.4 (b). As described above, the coolant 19 in the large-diameter hollow portion S1 generates a flow F6 directed radially outward from the central portion of the large-diameter hollow portion S1 along the bottom surface, and at the same time, communicates also in the small-diameter hollow portion S2. A downward flow (turbulent flow) F7 is generated through the portion P. The flow F6 along the bottom surface of the large-diameter hollow portion S1 is guided from the outside of the large-diameter hollow portion S1 to the vertical groove 20 (vertical rib 21) and turns around the ceiling surface 14b1, and the ceiling of the large-diameter hollow portion S1 It becomes the flow F8 along the surface 14b1, and merges with the flows F6 and F7 going downward at the central portion (communication portion P) of the large-diameter hollow portion S1.

  That is, as shown by arrows F6 → F8 → F6, an inner tumble flow is formed around the central axis L of the valve 10 in the coolant 19 in the large diameter hollow portion S1, and the cooling in the small diameter hollow portion S2 is performed. A turbulent flow as indicated by an arrow F7 is generated in the material 19.

  Furthermore, when the valve 10 shifts from the open state to the closed state (when the valve 10 is raised), the inertial force is applied to the coolant (liquid) 19 once moved upward in the small-diameter hollow portion S2 by the valve opening operation. Acts downward, the coolant 19 moves downward in the small-diameter hollow portion S2, but from the small-diameter hollow portion S21 near the end of the valve shaft having a large inner diameter to the small-diameter hollow portion S22 near the valve umbrella portion having a small inner diameter. When moving, as shown in FIG. 4B, a turbulent flow F10 is formed on the downstream side of the stepped portion 17 (below in FIG. 4B).

  In this way, during the opening and closing operation of the valve 10, the coolant 19 in the hollow portion S has a tumble flow indicated by arrows F1, F2, F3; F6, F8, arrows F4, F5, F7, F9, The turbulent flow indicated by F10 is formed, and the lower layer portion, middle layer portion, and upper layer portion of the coolant 19 in the hollow portion S are actively stirred, so that the heat drawing effect (thermal conductivity) in the valve 10 is obtained. There have been significant improvements.

  Further, as shown in FIG. 1, the stepped portion 17 in the small-diameter hollow portion S is provided at a position substantially corresponding to the end portion 3 b facing the exhaust passage 6 of the valve guide 3 and has a shaft end portion having a large inner diameter. By forming the small-diameter hollow portion S21 in the axial direction to be long in the axial direction, the contact area between the valve shaft portion 12 and the coolant 19 is increased without reducing the durability of the valve 10, and the heat transfer efficiency of the valve shaft portion 12 is increased. As a result, the small-diameter hollow portion S21 forming wall becomes thin, and the bulb 10 is also light. That is, the stepped portion 17 in the small-diameter hollow portion S has a predetermined position (in the valve shaft portion 12) that does not enter the exhaust passage 6 when the valve 10 is fully opened (lowered) as shown by the phantom line in FIG. A thin-walled small-diameter hollow portion S21 forming wall is provided at a predetermined position that is not easily affected by heat in the exhaust passage 6. Reference numeral 17X in FIG. 1 indicates the position of the stepped portion 17 in a state where the valve 10 is fully opened (lowered).

  Specifically, since the fatigue strength of the metal decreases as the temperature increases, the region near the valve umbrella portion 14 in the valve shaft portion 12 that is always in the exhaust passage 6 and exposed to high heat reduces the fatigue strength. It must be formed to a thickness that can withstand. On the other hand, in the region near the shaft end portion of the valve shaft portion 12 that is away from the heat source and is always in sliding contact with the valve guide 3 a, heat from the combustion chamber 4 and the exhaust passage 6 is transmitted via the coolant 19. However, since the transmitted heat is immediately radiated to the cylinder head 2 through the valve guide 3a, the temperature does not become as high as that near the valve umbrella portion 14.

  That is, since the fatigue strength does not decrease in the region near the shaft end portion in the valve shaft portion 12 than in the region near the valve umbrella portion 14, even if it is formed thin (the inner diameter of the small-diameter hollow portion S21 is increased), it is strong. There is no problem in (durability such as breakage due to fatigue).

  Therefore, in the present embodiment, the inner diameter of the small-diameter hollow portion S21 is increased, and first, the surface area of the entire small-diameter hollow portion S2 (contact area with the coolant 19) is increased, so that the valve shaft portion 12 Heat transfer efficiency is increased. Secondly, the total weight of the valve 10 is reduced by increasing the volume of the entire small-diameter hollow portion S2.

  Further, since the shaft end member 12b of the valve is not required to be as heat resistant as the shell 11, the valve 10 can be provided at low cost by using an inexpensive material having lower heat resistance than the material of the shell 11.

  Next, the manufacturing process of the hollow poppet valve 10 will be described with reference to FIG.

  First, as shown in FIG. 5A, a shell 11 in which an umbrella outer shell 14a provided with a truncated cone-shaped recess 14b and a shaft 12a are integrally formed is formed by a hot forging process. When forming the shell 11 (umbrella outer shell 14a), the bottom surface 14b1 of the recess 14b in the umbrella outer shell 14a is formed on a plane orthogonal to the shaft 12a (the central axis L of the shell 11). A longitudinal groove 20 (vertical rib 21) continuous in the circumferential direction is formed on the inner peripheral surface 14b2 of the recess 14b in the umbrella outer shell 14a.

  As a hot forging process, after forging a spherical part at the end of a heat-resistant steel bar with an extruding forging to manufacture the shell 11 from a heat-resistant steel block or an upsetter by extrusion forging that sequentially replaces the mold, Any of upsetting forging which forges shell 11 (umbrella outer shell 14a) using a metal mold may be used. In the hot forging process, an R-shaped fillet portion 13 is formed between the umbrella outer shell 14a and the shaft portion 12a of the shell 11, and a tapered face portion is formed on the outer peripheral surface of the umbrella outer shell 14a. 16 is formed.

  Next, as shown in FIG. 5 (b), the shell 11 is disposed so that the concave portion 14b of the umbrella outer shell 14a faces upward, and the umbrella extends from the bottom surface 14b1 of the concave portion 14b of the umbrella outer shell 14a to the shaft portion 12. The hole 14e corresponding to the small-diameter hollow portion S22 near the part is drilled by drilling (hole drilling step).

  By the hole drilling step, the recess 14b of the umbrella outer shell 14a constituting the large-diameter hollow portion S1 and the hole 14e on the shaft 12a side corresponding to the small-diameter hollow portion S22 communicate with each other, so that the recess 14b and the hole 14e In the communication portion, a bowl-shaped annular step portion 15 is formed as viewed from the concave portion 14b side.

  Next, as shown in FIG. 5C, a hole 14f corresponding to the small-diameter hollow portion S21 near the shaft end is drilled from the shaft end of the shell 11 (hole drilling step).

  Next, as shown in FIG. 5D, the shaft end member 12b is axially contacted with the shaft end portion of the shell 11 (shaft end member axial contact step).

  Next, as shown in FIG. 5 (e), a predetermined amount of coolant (solid) 19 is filled in the holes 14e of the recesses 14b of the umbrella outer shell 14a of the shell 11 (coolant charging step).

  Finally, as shown in FIG. 5 (f), a cap 18 is welded (for example, resistance welding) to the opening inner periphery 14c of the recess 14b of the umbrella outer shell 14a of the shell 11 under an argon gas atmosphere, and the valve The 10 hollow portions S are sealed (hollow portion sealing step). Note that the welding of the cap 18 may employ electron beam welding, laser welding, or the like instead of resistance welding.

  6 and 7 show a hollow poppet valve according to a second embodiment of the present invention.

  In the hollow poppet valve 10 of the first embodiment described above, the large-diameter hollow portion S1 in the valve umbrella portion 14 is formed in a truncated cone shape, whereas in the hollow poppet valve 10A of the second embodiment, The large-diameter hollow portion S1 ′ in the valve umbrella portion 14 is formed in a columnar shape having a low height, as in the prior art document 3.

  A vertical groove 20 ′ (vertical rib 21 ′) having an arcuate horizontal section is provided on the inner peripheral surface 14b2 ′ of the concave portion 14b ′ of the umbrella outer shell 14a ′ that defines the large-diameter hollow portion S1 ′. It is formed continuously with the pitch.

  Then, the cap 18 is welded to the opening 14c ′ of the cylindrical recess 14b of the umbrella outer shell 14a ′ so that the hollow portion S ′ is sealed, and the hollow portion S ′ is cooled with metal sodium or the like. Material 19 is loaded with an inert gas such as argon gas.

  Others are the same as those of the hollow poppet valve 10 of the first embodiment described above, and the same reference numerals are given to omit redundant description.

  That is, also in the hollow poppet valve 10A, as in the hollow poppet valve 10 of the first embodiment described above, the coolant 19 in the hollow portion S ′ is changed in accordance with the opening / closing operation (vertical operation) of the valve 10A. The inside of the hollow portion S ′ moves up and down due to the inertial force, and the coolant 19 in the large-diameter hollow portion S1 ′ at that time is directed upward along the outer peripheral surface from the bottom surface side of the large-diameter hollow portion S1 ′. By generating the flow, an inward tumble flow is formed around the central axis L ′ of the valve 10A.

  In particular, vertical grooves 20 ′ (vertical ribs 21 ′) having an arcuate horizontal section are formed on the inner peripheral surface 14 b 2 ′ of the concave portion 14 b ′ of the umbrella outer shell 14 a ′ defining the large-diameter hollow portion S 1 ′ at equal pitches in the circumferential direction. By being formed continuously, when the valve 10A reciprocates in the axial direction, the coolant is directed upward along the outer peripheral surface of the large-diameter hollow portion S1 ′ (the inner peripheral surface 14b2 ′ of the concave portion 14b ′). Since the generation of the flow 19 is promoted and the formation of the inner tumble flow is promoted in the coolant 19 in the large-diameter hollow portion S1 ′, heat transfer by the coolant 19 in the entire hollow portion S ′ is actively performed. Thus, the heat pulling effect of the valve 10A is enhanced.

  8 and 9 show a hollow poppet valve according to a third embodiment of the present invention.

  In the hollow poppet valves 10 and 10A of the first and second embodiments described above, the small-diameter hollow portion S2 in the valve shaft portion 12 includes a small-diameter hollow portion S21 having a large inner diameter near the valve shaft end portion, and the valve umbrella portion 14. In contrast to the small-diameter hollow portion S22 having a small inner diameter, the step portion 17 is formed in the middle of the small-diameter hollow portion S2 in the longitudinal direction. Is formed with a constant inner diameter in the longitudinal direction.

  Others are the same as those of the hollow poppet valve 10 of the first embodiment described above, and the same reference numerals are given to omit redundant description.

  That is, in the hollow poppet valves 10 and 10A of the first and second embodiments, the coolant 19 in the small-diameter hollow portion S2 is agitated by the stepped portion 17 provided in the small-diameter hollow portion S2. In the hollow poppet valve 10B of this embodiment, there is no such action (stirring action of the coolant 19 by the stepped portion 17). However, like the hollow poppet valve 10 of the first embodiment described above, the valve 10B is in the axial direction. When the reciprocating operation is performed, the flow of the coolant 19 toward the upper side along the inclined outer peripheral surface (inner peripheral surface of the recess) 14b2 of the large-diameter hollow portion S1 is promoted, and the inside of the large-diameter hollow portion S1 is promoted. Since the formation of the inner tumble flow in the coolant 19 is promoted, heat transfer by the coolant 19 in the entire hollow portion S ″ becomes active, and the heat drawing effect of the valve 10B is enhanced.

  FIG. 9 shows a manufacturing process of the hollow poppet valve 10B. Since the step portion is not provided in the small-diameter hollow portion S2 ″ in the valve shaft portion 12, a hole corresponding to the small-diameter hollow portion S2 ″ is formed. The manufacturing process is simplified, for example, the installation process is only one process, and the axial contact process for axially connecting the shaft end member is not required.

  First, as shown in FIG. 9A, a shell 11 'in which an umbrella outer shell 14a provided with a truncated cone-shaped recess 14b and a shaft portion 12 are integrally formed is formed by hot forging. Simultaneously with the molding of the shell 11 ′ (umbrella outer shell 14 a), longitudinal grooves 20 (vertical ribs 21) that are continuous in the circumferential direction are formed on the inner peripheral surface 14 b 1 of the recess 14 b in the umbrella outer shell 14 a.

  Next, as shown in FIG. 9B, a hole 14e ′ corresponding to the small-diameter hollow portion S2 ″ is drilled from the bottom surface 14b1 of the concave portion 14b of the umbrella outer shell 14a to the shaft portion 12 by drilling (hole). Drilling process).

  Next, as shown in FIG. 9C, a predetermined amount of coolant (solid) 19 is inserted into the hole 14e 'of the recess 14b of the umbrella outer shell 14a of the shell 11' (coolant loading step).

  Finally, as shown in FIG. 9 (d), under an argon gas atmosphere, a cap 18 is welded (for example, resistance welding) to the opening inner periphery 14c of the recess 14b of the umbrella outer shell 14a of the shell 11 ′, The hollow part S of the valve 10 is sealed (hollow part sealing step).

10, 10A, 10B Hollow poppet valve 11, 11 'Shell in which umbrella portion outer shell and shaft portion are integrally formed Valve shaft portion 12a Shaft portion 14 Valve umbrella portions 14a, 14a' Umbrella portion outer shells 14b, 14b 'Umbrella Recess 14b1 of the outer shell Circular ceiling surfaces 14b2, 14b2 'of the large-diameter hollow portion Recess inner peripheral surfaces 14c, 14c' of the outer shell of the umbrella portion Opening 15 of the concave portion of the outer shell of the umbrella portion Saddle-shaped annular stepped portion 17 which is the peripheral edge of the opening of the small-diameter hollow portion, annular stepped portions 20, 20 ′, longitudinal grooves 21, 21 ′, longitudinal ribs L, L ′, valve center axes S, S ′S ″, hollow portion S1 Frustum-shaped large-diameter hollow part S1 'Cylindrical large-diameter hollow part S2, S2' Linear small-diameter hollow part P Communication part 18 Cap 19 Coolant S21 Small-diameter hollow part near the shaft end S22 Small-diameter hollow part near the umbrella part F1 → F2 → F3; F6 → F8 tumble flow F4 5, F7 turbulence F9, F10 turbulence

Claims (3)

In a hollow poppet valve in which a hollow portion is formed from an umbrella portion to a shaft portion of a poppet valve in which an umbrella portion is integrally formed at a shaft end portion, and a coolant is loaded together with an inert gas in the hollow portion,
A disc-shaped large-diameter hollow portion is provided in the valve umbrella portion, and a linear small-diameter hollow portion provided in the valve shaft portion communicates perpendicularly to a ceiling surface of the disc-shaped large-diameter hollow portion. And, when the valve reciprocates in the axial direction, a hollow poppet valve in which a tumble flow around the central axis of the valve is formed at least in the coolant in the large-diameter hollow portion,
The large-diameter hollow part includes an umbrella outer shell formed with a recess that defines the entire ceiling side of the large-diameter hollow part, and a bottom surface of the large-diameter hollow part that is welded to the opening side of the recess. Consists of a cap to
A hollow poppet valve characterized in that longitudinal ribs are provided at equal intervals in the circumferential direction on the inner peripheral surface of the recess.   2. The hollow according to claim 1, wherein a vertical groove having a horizontal cross-section arc shape sandwiched between the vertical ribs is continuously provided in a circumferential direction on an inner peripheral surface of the concave portion of the umbrella outer shell. Poppet valve.   3. The hollow poppet valve according to claim 1, wherein the large-diameter hollow portion is formed in a truncated cone shape having a tapered outer peripheral surface that substantially follows the outer shape of the valve umbrella portion.

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