JP6063558B2 - Hollow poppet valve - Google Patents

Description

  The present invention relates to a hollow poppet valve in which a cooling material is loaded together with an inert gas in a hollow portion formed from an umbrella portion to a shaft portion of the poppet valve.

  In the following Patent Documents 1, 2, etc., a hollow part is formed from the umbrella part of the poppet valve integrally formed on one end side of the shaft part to the shaft part, and has a higher thermal conductivity than the base material of the valve. A hollow poppet valve is described in which a coolant (eg, metallic sodium, melting point about 98 ° C.) is loaded into the hollow portion 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.

  And in the past (patent documents 1 and 2), the communication part between the disk-shaped large-diameter hollow part in the umbrella part and the linear small-diameter hollow part in the shaft part is constituted by a smooth curved area (transition area where the inner diameter gradually changes). However, since this communicating part has a smoothly continuous shape, the coolant (liquid) together with the enclosed gas and the large-diameter hollow part during the opening / closing operation of the valve (reciprocating operation in the axial direction of the valve) It is thought that it can move smoothly between the small-diameter hollow portions, and the heat-drawing effect of the valve is improved.

  However, since the communication part between the large-diameter hollow part and the small-diameter hollow part is smoothly continuous, the coolant (liquid) moves smoothly between the large-diameter hollow part and the small-diameter hollow part according to the opening / closing operation of the valve. However, the coolant (liquid) in the hollow portion moves in the axial direction in a state where the upper layer portion, the middle layer portion, and the lower layer portion are maintained in a vertical relationship without being stirred.

  For this reason, it turned out that the heat in the coolant lower layer part on the side close to the heat source is not actively transmitted to the coolant middle layer part and the upper layer part, and the heat drawing effect (heat conductivity) is not sufficiently exhibited.

  Therefore, in Patent Document 3, the linear small-diameter hollow portion in the valve shaft portion is communicated so as to be substantially orthogonal to the ceiling surface of the frustoconical large-diameter hollow portion in the valve umbrella portion, and the large-diameter hollow portion to the small-diameter hollow portion. By suppressing the smooth movement of the coolant to the valve, the coolant in the large-diameter hollow part swivels in the vertical direction around the central axis of the valve when the valve opens and closes (the valve reciprocates in the axial direction). An invention in which a flow (hereinafter, this vertical swirl flow is referred to as a tumble flow) is formed, the coolant in the hollow portion is actively agitated, and the heat extraction effect (thermal conductivity) of the valve is improved. Filed (suggested).

WO2010 / 041337 JP2011-179328 PCT / JP2012 / 075452 (filed on October 2, 2012)

  However, the invention of Patent Document 3 has a structure in which a linear small-diameter hollow portion communicates with a ceiling surface of a large-diameter hollow portion having a truncated cone shape, and a part of the coolant has a communicating portion when the valve is opened and closed. Therefore, the momentum of the tumble flow formed on the coolant in the large-diameter hollow portion is weakened accordingly. For this reason, the coolant is not sufficiently agitated, and the heat drawing effect (thermal conductivity) is not sufficiently exhibited (first problem).

  Furthermore, although the heat of the valve head exposed to a high temperature is transmitted to the entire valve head through the coolant in the large-diameter hollow part, the movement of the coolant through the communication part is not smooth, so the valve shaft The heat transfer effect is not sufficiently exhibited in this point (second problem).

  Therefore, the inventor has the greatest feature of the invention of Patent Document 3, namely, “By forming the large-diameter hollow portion in the valve umbrella portion into a substantially truncated cone shape, the valve in the large-diameter hollow portion is opened and closed during the opening / closing operation. Assuming the configuration of `` forming a tumble flow in the coolant '', a pipe-shaped partition wall is provided between the ceiling surface and the bottom surface of the large-diameter hollow portion, and the small-diameter hollow portion is replaced with the bottom surface of the large-diameter hollow portion (valve umbrella surface). If it is separated to the large-diameter hollow part and both the hollow parts are filled with a coolant together with an inert gas, the coolant in both hollow parts will be in the hollow part when the valve is opened and closed. In particular, in the large-diameter hollow portion, the inertial force acting on the coolant is used only for the formation of the tumble flow, so that the momentary tumble flow is smoothly formed, as described above. The first problem can be solved and the heat of the valve umbrella Parts are by being directly transmitted to the valve shaft via the coolant in the small-diameter hollow portion, also can be solved second problem mentioned above, were considered.

  The present invention has been made on the basis of the above-mentioned knowledge of the inventor with respect to the prior art document. The purpose of the present invention is to provide a pipe-shaped partition wall in the large-diameter hollow portion in the valve umbrella portion, and to provide a small-diameter hollow portion in the valve shaft portion. An object of the present invention is to provide a hollow poppet valve that extends to the bottom surface of the large-diameter hollow portion (the back side of the front surface of the valve umbrella) and is separated from the large-diameter hollow portion, thereby improving the heat pulling effect.

In order to achieve the object, in the hollow poppet valve according to the present invention (Claim 1), a hollow portion is formed from the umbrella portion of the poppet valve integrally formed on one end side of the shaft portion to the shaft portion. In the hollow poppet valve in which the hollow portion is filled with a coolant together with an inert gas,
A substantially frustoconical large-diameter hollow portion having a tapered outer peripheral surface that substantially follows the outer shape of the umbrella portion is provided in the valve umbrella portion, and the ceiling surface of the large-diameter hollow portion is provided in the valve shaft portion. A linear small-diameter hollow portion communicating substantially orthogonal to the
The small-diameter hollow portion is extended to the bottom surface of the large-diameter hollow portion (the back side of the valve umbrella) between the bottom surface of the large-diameter hollow portion and the ceiling surface, and the small-diameter hollow portion is separated from the large-diameter hollow portion. A pipe-shaped partition wall is interposed, and both separated hollow parts are filled with an inert gas and a coolant, respectively. When the valve reciprocates in the axial direction, the cooling inside the large-diameter hollow part is performed. The material was configured such that a tumble flow was formed around the central axis of the valve.

  The small-diameter hollow portion is interposed between the bottom surface of the large-diameter hollow portion and the ceiling surface, and the small-diameter hollow portion is extended to the bottom surface of the large-diameter hollow portion (the back side of the valve umbrella front). As shown in the first embodiment, the pipe-shaped partition wall is separated from the valve shaft side, and the pipe-shaped partition wall is integrated with the structure of the pipe-shaped partition wall as shown in the second embodiment. It is conceivable that a pipe-shaped partition wall is integrated with the back side of the cap constituting the.

  In general, the amount of coolant loaded in the hollow portion is superior in the heat-drawing effect (thermal conductivity), but as the amount increases, the heat-drawing effect on the loaded amount does not increase, and particularly in the large-diameter hollow portion. If the amount of the coolant to be charged is too large, it is difficult to form a tumble flow. Therefore, the amount of coolant to be charged is preferably about 1/2 to 4/5 of the volume of each hollow portion.

  (Operation) When the valve shifts from the closed state to the open state (when the valve descends), as shown in FIG. 2A, the coolant (liquid) in the small-diameter hollow portion and the large-diameter hollow portion is used. Since the inertial force acts upward, each moves upward.

  Specifically, since the small-diameter hollow portion in the valve shaft portion extends linearly, the entire coolant in the small-diameter hollow portion moves smoothly upward. On the other hand, the large-diameter hollow portion in the valve umbrella portion has a tapered outer peripheral surface that substantially follows the outer shape of the umbrella portion, and is formed in an annular substantially truncated cone shape having a pipe-shaped partition wall as the inner peripheral surface. As shown in FIG. 2 (a), the inertial force (upward) acting on the coolant near the center of the large-diameter hollow portion is larger than the inertial force acting on the coolant near the periphery of the large-diameter hollow portion. For this reason, as shown to Fig.3 (a), the flow F1 which goes to a radial direction outer side along a ceiling surface from the large diameter hollow part center vicinity generate | occur | produces. At this time, on the bottom surface side of the large-diameter hollow portion, the coolant near the center of the large-diameter hollow portion moves upward, so that the bottom surface side near the center of the large-diameter hollow portion becomes negative pressure, from the radially outer side to the inner side. A flowing flow F3 is generated, and accompanying this, a downward flow F2 is generated along the tapered outer peripheral surface of the large-diameter hollow portion.

  That is, in the coolant in the large-diameter hollow portion, as shown by arrows F1 → F2 → F3 → F1, a swirling flow (hereinafter referred to as an outer tumble flow) T1 is formed around the central axis of the valve. Is done.

  Further, when the valve shifts from the open state to the closed state (when the valve is raised), as shown in FIG. 2B, the coolant (liquid) in the small-diameter hollow portion and the large-diameter hollow portion is used. Since the inertial force acts downward, each moves downward.

  Specifically, in the small-diameter hollow portion, the entire coolant that has moved upward when the valve transitions from the valve open state to the valve closed state smoothly moves downward. On the other hand, in the large-diameter hollow portion, the inertial force (downward) acting on the coolant near the center of the large-diameter hollow portion is inertia acting on the coolant near the large-diameter hollow portion as shown in FIG. Greater than power. For this reason, as shown in FIG.3 (b), in the coolant in a large diameter hollow part, the flow F6 which goes to a radial direction outward along a bottom face from the large diameter hollow part center side generate | occur | produces. At this time, on the ceiling surface side of the large-diameter hollow portion, the coolant near the center of the large-diameter hollow portion moves downward, so that the ceiling surface side near the center of the large-diameter hollow portion becomes negative pressure, and from the outside in the radial direction. An inward flow F8 is generated, and accordingly, an upward flow F7 is generated along the tapered outer peripheral surface of the large-diameter hollow portion.

  That is, as indicated by arrows F6 → F7 → F8 → F6, a swirling flow (hereinafter referred to as an inner tumble flow) T2 is formed around the central axis of the valve in the large-diameter hollow portion coolant. Is done.

  Thus, by opening and closing the valve, the tumble flow T1, T2 shown in FIG. 3 is formed in the coolant in the large-diameter hollow portion of the valve, and the upper layer portion of the coolant in the entire large-diameter hollow portion, Since the middle layer portion and the lower layer portion are actively stirred, the heat drawing effect (thermal conductivity) of the valve is remarkably improved.

  In the prior art document 3, since the small-diameter hollow portion communicates with the ceiling surface of the large-diameter hollow portion, a part of the coolant passes through the communicating portion when the valve is opened and closed. And the momentum of the tumble flow formed in the coolant in the large-diameter hollow portion is weakened so that the coolant in the large-diameter hollow portion may not be sufficiently agitated. In item 1, since the large-diameter hollow portion and the small-diameter hollow portion are separated by the partition wall, the coolant in both the hollow portions smoothly moves in the vertical direction in each hollow portion when the valve is opened and closed. In the large-diameter hollow portion, the inertial force acting on the coolant is used only for the formation of the tumble flow, so that a vigorous tumble flow is formed smoothly, the coolant is sufficiently stirred, and the heat in the valve umbrella portion The pulling effect is increased.

  And most of the heat of the valve head exposed to a high temperature is efficiently transmitted to the valve head through the coolant in the large diameter hollow part, and a part of the heat of the valve head is further transferred to the large diameter hollow part. Since it is directly transmitted to the valve shaft portion through the coolant in the small-diameter hollow portion extending to the bottom surface, the heat pulling effect (thermal conductivity) of the entire valve is enhanced.

  According to a second aspect of the present invention, in the hollow poppet valve according to the first aspect, the inner peripheral surface of the valve shaft portion defining the small-diameter hollow portion and the inner peripheral surface of the pipe-shaped partition wall are flush with each other.

  (Operation) Since the inner peripheral surface of the small-diameter hollow portion extending from the inside of the valve shaft portion to the back side of the valve umbrella is formed to be flush with the axial direction including the pipe-shaped partition wall, when the valve opens and closes (valve As the coolant in the small-diameter hollow portion moves more smoothly in the vertical direction during the vertical movement, the heat transfer from the valve head to the valve shaft becomes active.

  The hollow poppet valve according to claim 1 or 2, wherein an inner diameter of the small-diameter hollow portion near the valve shaft end is formed larger than an inner diameter of the small-diameter hollow portion near the valve umbrella portion, An annular stepped portion is provided at a predetermined axial position in the small-diameter hollow portion, and the coolant is loaded up to a position beyond the stepped portion.

  (Operation) When the valve shifts from the closed state to the open state (when the valve descends), the coolant (liquid) in the small-diameter hollow part is changed from the small-diameter hollow part near the valve umbrella part having a small inner diameter to the inner diameter. When moving to the small-diameter hollow portion near the large valve shaft end, as shown in FIG. 3A, a turbulent flow F9 is formed on the downstream side of the stepped portion, and the coolant in the small-diameter hollow portion is agitated. .

  On the other hand, when the valve transitions from the open state to the closed state (when the valve rises), the coolant (liquid) once moved upward in the small-diameter hollow portion by the valve-opening operation is When moving from the small-diameter hollow portion near the portion to the small-diameter hollow portion near the valve umbrella portion having a small inner diameter, a turbulent flow F10 is formed on the downstream side of the annular stepped portion as shown in FIG. The coolant in the small diameter hollow part is agitated.

  Thus, turbulent flow is generated in the vicinity of the step portion when the coolant moves in the axial direction in the small-diameter hollow portion in accordance with the opening / closing operation (vertical direction operation) of the valve, thereby cooling the inside of the small-diameter hollow portion. Since the material is agitated, the heat drawing effect (thermal conductivity) at the valve shaft is further increased.

According to the hollow poppet valve of the present invention, the entire coolant in the small-diameter hollow portion moves smoothly in the axial direction during the opening / closing operation (vertical movement operation) of the valve, and the coolant in the large-diameter hollow portion. The whole is actively stirred by the tumble flow, and most of the heat on the valve head is efficiently transferred to the valve head through the coolant in the large-diameter hollow part, and part of the heat on the valve head is also transferred. Since it is directly transmitted to the valve shaft through the coolant in the small-diameter hollow portion, the heat pulling effect (thermal conductivity) in the valve umbrella is remarkably improved, and the performance of the engine is improved.

  According to the second aspect, the heat transfer efficiency by the coolant in the small-diameter hollow portion is increased by the amount of smooth movement of the coolant in the small-diameter hollow portion in the axial direction, and the heat drawing effect (thermal conductivity) of the valve is increased. Further improvement.

  According to the third aspect, since the coolant in the small-diameter hollow portion is also actively agitated with the opening / closing operation (vertical operation) of the valve, the heat drawing effect (thermal conductivity) of the valve is further improved. Is done.

It is a longitudinal cross-sectional view of the hollow poppet valve which is the 1st Example of this invention. 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 (B) is a figure which shows a motion of the coolant at the time of transfering from a valve opening state to a valve closing state. The manufacturing process of the hollow poppet valve is shown, wherein (a) is a hot forging process for forging a shell which is an intermediate product of the valve, and (b) is a hole drilling process for drilling a hole corresponding to a small-diameter hollow part near the umbrella. (C) is a hole drilling step for drilling a hole corresponding to a small-diameter hollow portion near the shaft end, (d) is a step forming step for forming a step for press-fitting a partition wall, and (e) is a shaft end member. (F) is a partition press-fitting and brazing step for press-fitting and brazing the partition wall, (g) is a coolant filling step for filling the coolant into the small-diameter hollow portion and the large-diameter hollow portion, respectively ( h) is a diagram showing a step of joining a cap to an opening of a concave portion (large diameter hollow portion) of the umbrella outer shell (large diameter hollow portion sealing step). It is a longitudinal cross-sectional view of the hollow poppet valve which is the 2nd Example of this invention. The manufacturing process of the hollow poppet valve is shown, (a) is a hot forging process for forging a shell which is an intermediate product of the valve, (b) is a hole drilling process for drilling a hole corresponding to a small-diameter hollow part, (c ) Is a step portion forming step for forming a step portion for press-fitting a partition wall into the opening of the hole, (d) is a coolant filling step for filling the small diameter hollow portion and the large diameter hollow portion with a coolant, and (e) is a cap. It is a figure which shows the process (large-diameter hollow part sealing process) which press-fits the side partition in a hole, and joins a cap to the opening part of the recessed part (large-diameter hollow part) of an umbrella part outer shell.

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

  1 to 4 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 structure in which a valve umbrella portion 14 is integrally formed on one end side of a valve shaft portion 12 extending straight through an R-shaped fillet portion 13 whose outer diameter gradually increases. In the alloy hollow poppet valve, a tapered face portion 16 is provided on the outer periphery of the valve umbrella portion 14.

  Inside the hollow poppet valve 10, a large-diameter hollow portion S1 in the valve umbrella portion 14 and a small-diameter hollow portion S2 in the valve shaft portion 12 are disposed so as to be orthogonal to each other. Each of the hollow portions S1 and S2 is filled with a coolant 19 together with an inert gas.

  The outer shape of the large-diameter hollow portion S1 is formed in a truncated cone shape having a circular outer surface 14b2 that substantially follows the outer shape of the circular ceiling surface 14b1 and the valve umbrella portion 14, and the small-diameter hollow portion S2 is formed in the valve shaft portion 12. And is formed in a long and narrow cylindrical shape coaxial.

  That is, the small-diameter hollow portion S2 in the valve shaft portion 12 is a circle that is fixedly integrated with an opening portion of the small-diameter hollow portion S2 to the large-diameter hollow portion S2, and the tip portion is in pressure contact with the bottom surface of the large-diameter hollow portion S2. The pipe-shaped partition wall 15 extends to the bottom surface of the large-diameter hollow portion S2. For this reason, the large-diameter hollow portion S2 has an annular space (tapered outer peripheral surface 14b2 and circular-pipe-shaped partition wall 15 surrounding the circular pipe-shaped partition wall 15 that defines the extended lower end of the small-diameter hollow portion S2. Is an annular, generally frustoconical space). In other words, the small-diameter hollow portion S2 in the valve shaft portion 12 penetrates the large-diameter hollow portion S2 by the circular pipe-shaped partition wall 15 interposed between the ceiling surface 14b1 and the bottom surface of the large-diameter hollow portion S2. By extending to the bottom surface of the large-diameter hollow portion S2, the large-diameter hollow portion S2 defined around the partition wall 15 is separated.

  Specifically, a shaft-integrated shell (hereinafter simply referred to as a shell) 11 is a valve intermediate product in which an umbrella outer shell 14a is integrally formed on one end side of a shaft portion 12a in which a hole corresponding to the small-diameter hollow portion S2 is formed. And a circular pipe-like partition wall 15 fixed and integrated with the opening of the small-diameter hollow portion S2 in the recess 14b of the umbrella outer shell 14a, and the opening-side inner peripheral surface 14c of the recess 14b of the umbrella outer shell 14a. The large-diameter hollow portion S1 in the valve umbrella portion 14 and the inside of the valve shaft portion 12 are formed by the disc-shaped cap 18 constituting the valve umbrella surface 18a and the shaft end member 12b axially contacted with the shaft portion 12a of the shell 11. The hollow poppet valve 10 from which the small-diameter hollow portion S2 is separated is configured, and the hollow portions S1 and S2 are loaded with a coolant 19 such as metallic sodium together with an inert gas such as argon gas. As the loading amount of the coolant 19, for example, an amount of about 1/2 to 4/5 of the volume of the hollow portions S1 and S2 is loaded.

  In general, the amount of coolant loaded in the hollow portion is superior in the heat-drawing effect (thermal conductivity), but as the amount increases, the heat-drawing effect on the loaded amount does not increase, and particularly in the large-diameter hollow portion. If the amount of the coolant to be charged is too large, it is difficult to form a tumble flow. Therefore, the amount of coolant to be charged is preferably about 1/2 to 4/5 of the volume of each hollow portion.

  In addition, the opening of the small-diameter hollow portion S2 that opens into the recess 14b (the circular bottom 14b1) of the umbrella outer shell 14a that defines the large-diameter hollow portion S1 has a thickness and press-fitting allowance for the pipe-shaped partition wall 15. Is formed, and the inner peripheral surface of the partition wall 15 press-fitted and fixed to the step portion 15a is the inner periphery of the linear small-diameter hollow portion S2 in the valve shaft portion 12. The amount of protrusion of the partition wall 15 into the large-diameter hollow portion S1 is set so as to be in pressure contact with the cap 18 that defines the bottom surface of the large-diameter hollow portion S1.

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

  The shell 11 and the cap 18 that are exposed to the high-temperature gas in the combustion chamber 4 and the exhaust passage 6 are made of heat-resistant steel. The shaft end member 12b that does not require as much heat resistance as 18 is made of a general steel material.

  In the hollow poppet valve 10 configured in this way, as will be described in detail later, when the valve 10 opens and closes, the coolant 19 in the large-diameter hollow portion S1 moves in the vertical direction by the acting inertial force. At this time, as shown in FIGS. 3A and 3B, tumble flows T1 and T2 are formed, and the upper layer portion, middle layer portion, and lower layer portion of the coolant 19 are actively stirred. The heat drawing effect (thermal conductivity) of the umbrella portion 14 of the valve 10 is greatly improved.

  The small-diameter hollow portion S2 includes a small-diameter hollow portion S21 near the valve shaft end portion having a relatively large inner diameter d1 and a small-diameter hollow portion S22 near the valve umbrella portion 14 having a relatively small inner diameter d2 (d2 <d1). An annular stepped portion 17 is formed between the small-diameter hollow portions S21 and S22, and the coolant 19 is loaded up to a position beyond the stepped portion 17.

  For this reason, as will be described in detail later, when the coolant 19 in the small-diameter hollow portion S2 moves up and down by the inertial force acting when the valve 10 opens and closes, FIGS. ), Turbulent flows F9 and F10 are generated in the vicinity of the stepped portion 17, and the coolant 19 is agitated, so that the heat drawing effect (thermal conductivity) in the valve shaft portion 12 is improved. .

  Next, the movement of the coolant 19 in the hollow portions S1, S2 when the valve 10 is opened and closed will be described in detail with reference to FIGS.

  When the valve 10 transitions from the closed state to the open state (when the valve 10 is lowered), as shown in FIG. 2A, the coolant (liquid) in the small-diameter hollow portion S2 and the large-diameter hollow portion S1. ) 19 respectively move upward because the inertial force acts upward.

  Specifically, the large-diameter hollow portion S1 is formed in an annular substantially truncated cone shape having a circular pipe-shaped partition wall 15 as an inner peripheral surface and a tapered outer peripheral surface 14b2 substantially following the outer shape of the umbrella portion 14. Therefore, as shown in FIG. 2A, the inertial force (upward) acting on the coolant near the center of the large-diameter hollow portion S1 is larger than the inertial force acting on the coolant near the periphery of the large-diameter hollow portion. For this reason, as shown to Fig.3 (a), the flow F1 which goes to a radial direction outer side along the ceiling surface 14b1 generate | occur | produces from the large-diameter hollow part S1 center side. At this time, on the bottom surface side of the large-diameter hollow portion S1, the coolant closer to the center of the large-diameter hollow portion S1 moves upward, so that the bottom surface side near the center of the large-diameter hollow portion S1 becomes negative pressure and radially outward. A flow F3 directed inward from the inside is generated, and accompanying this, a flow F2 directed downward along the tapered outer peripheral surface 14b2 of the large-diameter hollow portion S1 is generated.

  Thus, as shown by arrows F1 → F2 → F3 → F1, an outer tumble flow T1 is formed around the central axis L of the valve in the coolant 19 in the large-diameter hollow portion S1.

  Further, since the small-diameter hollow portion S2 extends linearly, the entire coolant 19 moves smoothly upward, and when the coolant 19 moves upward as shown in FIG. A turbulent flow F9 is generated on the downstream side near 17.

  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. 2B, the coolant in the small diameter hollow portion S2 and the large diameter hollow portion S1. The (liquid) 19 moves downward because the inertial force acts downward.

  In the large-diameter hollow portion S1, the inertial force (downward) acting on the coolant 19 near the center of the large-diameter hollow portion S1 is, as shown in FIG. 2B, the coolant 19 near the large-diameter hollow portion S1. Greater than the inertial force acting on For this reason, as shown in FIG.3 (b), in the coolant 19 in large diameter hollow part S1, the flow F6 which goes to a radial direction outer side along the bottom face from large diameter hollow part S1 center generate | occur | produces. At this time, on the ceiling surface 14b1 side of the large-diameter hollow portion S1, the coolant 19 near the center of the large-diameter hollow portion S1 moves downward, so that the ceiling surface 14b1 side near the center of the large-diameter hollow portion S1 becomes negative pressure. Accordingly, a flow F8 directed from the radially outer side to the inner side is generated, and accordingly, a flow F7 directed upward along the tapered outer peripheral surface 14b2 of the large-diameter hollow portion S1 is generated.

  That is, in the coolant 19 in the large-diameter hollow portion S1, an inward tumble flow T2 is formed around the central axis L of the valve 10, as indicated by arrows F6 → F7 → F8 → F6.

  Further, since the small-diameter hollow portion S2 extends linearly, the entire coolant 19 once raised when the valve 10 shifts from the open state to the closed state (when the valve 10 is raised) smoothly and downwards. As shown in FIG. 3B, when the coolant 19 moves downward, a turbulent flow F10 is generated on the downstream side in the vicinity of the stepped portion 17.

  Thus, the coolant 19 in the small-diameter hollow portion S2 of the valve 10 is agitated by the turbulent flows F9 and F10 generated when the valve 10 opens and closes, and the coolant 19 in the large-diameter hollow portion S1 of the valve 10 is stirred. Since the upper layer portion, the middle layer portion, and the lower layer portion are actively stirred by the tumble flows T1 and T2 formed when the valve 10 is opened and closed, the heat drawing effect (thermal conductivity) of the valve 10 is remarkably increased. Has been enhanced.

  In particular, a part of the heat of the valve head 18a exposed to high temperature passes through the coolant 19 in the small-diameter hollow portion S2 that extends to the bottom surface of the large-diameter hollow portion S1 when the valve 10 is opened and closed. Since it is transmitted directly to the shaft portion 12, the heat drawing effect (thermal conductivity) in the valve 10 is further enhanced.

  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 S2 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 indicated by the phantom line in FIG. The thin-walled small-diameter hollow portion S21 forming wall is provided at a predetermined position in the valve insertion hole 3 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. 4A, an umbrella outer shell 14a provided with a truncated cone-shaped concave portion 14b corresponding to the large-diameter hollow portion S1 and a shaft portion 12a were integrally formed by hot forging. The shell 11 is formed. A bottom surface 14b1 of the concave portion 14b of the umbrella outer shell 14a is formed by a plane orthogonal to the shaft portion 12a (the central axis L of the shell 11).

  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. 4B, the shell 11 is arranged so that the concave portion 14b of the umbrella outer shell 14a faces upward, and the small hollow portion closer to the umbrella from the concave portion 14b side of the umbrella outer shell 14a. The circular hole 14e corresponding to S22 is drilled by drilling (hole drilling step).

  Next, as shown in FIG. 4C, a circular hole 14f corresponding to the small-diameter hollow portion S21 closer to the shaft end is drilled from the end of the shaft 12a (hole drilling step).

  Next, as shown in FIG. 4D, a step portion 15a for press-fitting the partition wall 15 is formed on the opening side of the circular hole 14e in the concave portion 14b of the umbrella outer shell 14a by cutting or drilling ( Stepped portion forming step).

  Next, as shown in FIG. 4E, the shaft end member 12b is axially contacted with the shaft portion 12a of the shell 11 (shaft end member axial contact step).

  Next, as shown in FIG. 4 (f), a pipe-shaped partition wall 15 is press-fitted into the stepped portion 15a of the circular hole 14e opened in the concave portion 14b of the umbrella outer shell 14a, and brazed as necessary ( Bulkhead press-fitting and brazing process).

  Next, as shown in FIG. 4G, a predetermined amount of coolant (solid) 19 is filled in the circular holes 14e and the recesses 14b (coolant filling step).

  Next, as shown in FIG. 4 (h), a cap 18 is arranged in the concave portion 14b (the inner peripheral surface 14c of the opening side) of the umbrella outer shell 14a in an argon gas atmosphere, and the tip of the pipe-shaped partition wall 15 is placed. The cap 18 is joined to the recess 14b of the umbrella outer shell 14a (for example, resistance joining) in a state where the cap 18 is pressed and held on the part, and the large-diameter hollow part S1 is sealed (large-diameter hollow part sealing step). Finally, the valve 10 is completed by performing processing for forming the cotter groove 12c at the shaft end. For joining the cap 18, electron beam welding, laser welding, or the like may be employed instead of resistance joining.

  Note that either of the hole drilling step shown in FIG. 4C and the step forming step shown in FIG. 4D may be performed first.

  5 and 6 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, a circular pipe-like shape fixed to and integrated with the opening (step portion 15a) of the small-diameter hollow portion S2 that opens into the recess 14b of the umbrella outer shell 14a of the shell 11. The partition wall 15 extends the small-diameter hollow portion S2 in the valve shaft portion 12 to the bottom surface of the large-diameter hollow portion S1 (the back surface of the cap 18), and separates the small-diameter hollow portion S2 from the large-diameter hollow portion S1. In the hollow poppet valve 10A of the second embodiment, the small-diameter hollow portion S2 ′ is extended to the bottom surface of the large-diameter hollow portion S1 (the back surface of the cap 18) on the back side of the cap 18 constituting the valve head 18a. A circular pipe-shaped partition wall 15A that separates the small-diameter hollow portion S2 ′ from the large-diameter hollow portion S1 is fixed and integrated.

  That is, a pipe-shaped partition wall 15A is fixed and integrated on the back surface side of the cap 18 by brazing or welding, for example, while the small-diameter hollow portion S2 ′ in the shell 11A (the concave portion 14b of the umbrella outer shell 14a). In the opening, a step 15b is formed in which the tip of a pipe-shaped partition wall 15A integrated with the cap 18 can be press-fitted.

  Then, with the tip of the pipe-shaped partition wall 15A being press-fitted into the stepped portion 15b at the center of the recess 14b of the umbrella outer shell 14a, the cap 18 is in the recess 14b (opening inner periphery 14c of the umbrella outer shell 14a of the shell 11A). ) (For example, resistance bonding), the large-diameter hollow portion S1 is hermetically sealed. In addition, the distal end portion of the pipe-shaped partition wall 15A is press-fitted and held in the step portion 15b of the small-diameter hollow portion S2 ', so that the small-diameter hollow portion S2' separated from the large-diameter hollow portion S1 is also sealed. In these sealed large-diameter hollow portion S1 and small-diameter hollow portion S2 ', a coolant 19 such as metallic sodium is loaded together with an inert gas such as argon gas.

  Further, the inner peripheral surface of the partition wall 15A press-fitted and fixed to the step portion 15b is flush with the inner peripheral surface of the linear small-diameter hollow portion S2 ′ in the valve shaft portion 12, so that the valve 10A opens and closes. At this time (when the valve 10A moves up and down), the coolant 19 in the small-diameter hollow portion S2 ′ can move smoothly in the vertical direction.

  Further, the small-diameter hollow portion S2 ′ of the valve 10A of the present embodiment is configured with a constant inner diameter in the axial direction, and there is no stepped portion 17 formed in the small-diameter hollow portion S2 of the valve 10 of the first embodiment. Therefore, when the valve 10A is opened and closed, no turbulent flow is generated in the coolant 19 in the small diameter hollow portion S2 ′.

  Other configurations are the same as those of the hollow poppet valve 10 according to the first embodiment described above, and the same reference numerals are given, and redundant description thereof is omitted.

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

  First, as shown in FIG. 6A, a shell 11A in which an umbrella outer shell 14a provided with a truncated cone-shaped recess 14b and a valve shaft portion 12 are integrally formed is formed by hot forging.

  Next, as shown in FIG. 6B, the shell 11A is arranged so that the concave portion 14b of the umbrella outer shell 14a faces upward, and corresponds to the small-diameter hollow portion S2 ′ from the concave portion 14b side of the umbrella outer shell 14a. The circular hole 14e 'to be drilled is drilled (hole drilling step).

  Next, as shown in FIG. 6C, a step 15b for press-fitting the pipe-shaped partition wall 15A into the opening of the circular hole 14e 'in the recess 14b of the umbrella outer shell 14a is cut or drilled. (Partition wall press-fitting hole forming step).

  Next, as shown in FIG. 6D, a predetermined amount of coolant (solid) 19 is filled in the circular hole 14e 'and the recess 14b of the umbrella outer shell 14a (coolant filling step). Since the coolant (solid) 19 is in the form of clay at normal temperature, it can be inserted into the circular hole 14e 'in the form of a thin rod, or it can be filled in a predetermined position in the recess 14b of the umbrella outer shell 14a. .

  Next, as shown in FIG. 6 (e), the pipe 18 is inserted into the stepped portion 15b of the circular hole 14e 'in the concave portion 14b of the umbrella outer shell 14a while press fitting the pipe-shaped partition wall 15A under an argon gas atmosphere. It arrange | positions to the opening side inner peripheral surface 14c of the recessed part 14b of the umbrella part outer shell 14a, and joins the cap 18 to the umbrella part outer shell 14a. Finally, the valve 10A is completed by performing processing for forming the cotter groove 12c at the shaft end.

  In the valve 10A of the second embodiment, since the small-diameter hollow portion S2 ′ is formed with a constant inner diameter in the axial direction, the step of drilling a hole corresponding to the small-diameter hollow portion S2 ′ may be performed in one step. Furthermore, the process of manufacturing the valve is simplified, for example, the process of axially contacting the shaft end member is not required.

  In the above-described embodiment, the small diameter hollow portion S2 is interposed between the bottom surface of the large diameter hollow portion S1 and the ceiling surface, and extends to the bottom surface of the large diameter hollow portion S1 (the back side of the valve umbrella front). The pipe-shaped partition that separates the hollow part S2 from the large-diameter hollow part S1 is composed of circular pipe-shaped partition walls 15 and 15A, but is composed of a bellows-structured pipe-shaped partition that can expand and contract in the axial direction. You may make it interpose in the form compressed to the axial direction between the bottom face and ceiling surface of large diameter hollow part S1.

DESCRIPTION OF SYMBOLS 10, 10A Hollow poppet valve 11, 11A Shell 12 which is a valve | bulb intermediate member which integrally formed the umbrella part outer shell and the axial part Valve shaft part 12a Shaft part 12b Shaft end member 14 Valve umbrella part 14a Umbrella outer shell 14b Concave part 14b1 of the outer shell Circular ceiling surface of the large-diameter hollow part (circular bottom surface of the concave part)
14b2 Tapered outer peripheral surface of large-diameter hollow part (tapered inner peripheral surface of recess)
15, 15A Circular pipe-shaped partition walls 15a, 15b Stepped portion 17 for press-fitting partition wall Stepped portion 18 in small-diameter hollow portion Cap 18a Valve umbrella table 19 Coolant L Central axis S1 of valve Conical large-diameter hollow portion S2 Linear shape Small-diameter hollow portion S2 ′ Linear small-diameter hollow portion S21 Small-diameter hollow portion S22 near the shaft end portion Small-diameter hollow portion T1, T2 near the umbrella portion Tumble flow F9, F10 Turbulent flow

Claims (2)

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 on one end side of the shaft portion, and a coolant is loaded together with an inert gas in the hollow portion.
A large-diameter hollow portion having a substantially truncated cone shape having a tapered outer peripheral surface that substantially follows the outer shape of the umbrella portion is provided in the valve umbrella portion, and the ceiling of the large-diameter hollow portion is provided in the valve shaft portion. A linear small-diameter hollow portion communicating substantially orthogonal to the surface is provided,
The small-diameter hollow portion is extended to the bottom surface of the large-diameter hollow portion (the back side of the valve umbrella) between the bottom surface of the large-diameter hollow portion and the ceiling surface, and the small-diameter hollow portion is separated from the large-diameter hollow portion. While a pipe-shaped partition wall is interposed,
Both the hollow parts separated by the partition wall are filled with a coolant together with an inert gas, and when the valve reciprocates in the axial direction, the coolant in the large-diameter hollow part is moved around the central axis of the valve. be empty poppet valve in which data tumble flow Ru is formed,
The inner diameter of the small-diameter hollow portion near the valve shaft end is formed larger than the inner diameter of the small-diameter hollow portion near the valve umbrella, and an annular step portion is provided at a predetermined axial position in the small-diameter hollow portion.
A hollow poppet valve in which a turbulent flow is formed on the downstream side of the step portion when the coolant is loaded to a position beyond the step portion and the valve reciprocates in the axial direction .   2. The hollow poppet valve according to claim 1, wherein an inner peripheral surface of a valve shaft portion defining the small-diameter hollow portion and an inner peripheral surface of the pipe-shaped partition wall are configured to be flush with each other.

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