JP2009221974A - Hollow valve - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To quickly raise the temperature inside a combustion chamber when starting an internal combustion engine or in low-load operation thereof, and to prevent a valve from an excessively high temperature in high-load operation of the internal combustion engine. <P>SOLUTION: A refrigerant 50 formed from a low-melting point material is sealed in a hollow hole 3. In the hollow hole 3, a temperature sensitive opening/closing valve device 40 for opening/closing a communication opening communicated with an upper chamber 3a and a lower chamber 3b by opening/closing in response to the temperature inside the hollow hole 3 is provided. The temperature sensitive opening/closing valve device 40 opens in a process, in which the temperature inside the hollow hole 3 rises, and closes in a process, in which the temperature inside the hollow hole 3 lowers. A valve opening set temperature and a valve closing set temperature of the temperature sensitive opening/closing valve device 40 are respectively set at a temperature higher than a melting point of the low-melting point material within a range of a temperature change inside the hollow hole 3. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a hollow valve, and more particularly to a hollow valve suitable for application to an exhaust valve of an internal combustion engine.

  In recent years, there has been a strong demand for high output and low fuel consumption in internal combustion engines such as gasoline engines. However, if the engine performance is improved to meet the demand for higher output and lower fuel consumption, the temperature of the combustion chamber increases. For this reason, in particular, the heat load on the exhaust valve increases.

  Conventionally, there is a hollow valve in which a hollow hole is formed from an umbrella part to a shaft part (stem part), and a refrigerant made of a low melting point metal such as Na, Sn—Bi alloy or Sn—Bi—Zn alloy is enclosed in the hollow hole. It is known (see, for example, Patent Document 1).

In this hollow bulb, a low melting point metal such as Na melts at a high temperature above the melting point. For this reason, since the liquid metal is stirred in the hollow hole during the high temperature operation of the valve in which the temperature in the hollow hole is equal to or higher than the melting point of the low melting point metal, the bubbles can be cooled by a large heat exchange action.
JP-A-9-184404

  By the way, at the time of engine start and low load operation, particularly in the case of a direct injection engine, it is desired to quickly raise the temperature of the combustion chamber in order to promote fuel vaporization. If the temperature of the combustion chamber is too low, the fuel may not burn but become unburned gas, which may lead to deterioration of HC emission and fuel consumption.

  However, with the conventional hollow valve described above, it is difficult to quickly raise the temperature of the combustion chamber when starting the engine, as described below.

  In general, a metal has a higher thermal conductivity in the solid phase than in the liquid phase. And the melting | fusing point of Na mainly used as a refrigerant | coolant is about 98 degreeC with pure Na. For this reason, when the engine is started, Na as a refrigerant exists in the hollow hole from the umbrella portion to the shaft portion as a solid phase. The thermal conductivity of Na in the solid phase is about 132 to 137 W / m · K, which is higher than the thermal conductivity of heat-resistant steel used for valves. Then, since the temperature in the combustion chamber is lower than the melting point of Na for several tens of seconds after the engine is started, the heat release from the valve is increased due to the high thermal conductivity through the solid phase Na having a high thermal conductivity. Therefore, it is difficult to quickly raise the temperature of the combustion chamber.

  If a low-melting-point alloy having a lower melting point and lower thermal conductivity in the solid phase is used as the refrigerant, the high heat conduction effect via the solid-phase refrigerant can be reduced immediately after the engine is started. However, if a low-melting-point alloy with low thermal conductivity in the solid phase is used as the refrigerant, the thermal conductivity is generally lower in the liquid phase, so that the refrigerant inherently cools the valve at high load when the temperature of the combustion chamber is high. May impair the function of. Even in this case, the refrigerant that has been heated to the melting point or higher and liquefied is stirred in the hollow hole, so that the combustion chamber, the bubble umbrella, the liquid phase refrigerant, the valve shaft, and the upper end of the shaft A large heat flow is generated in sequence to the valve guide and head cooling water in contact with each other. For this reason, it is still difficult to quickly raise the temperature in the combustion chamber after the engine is started.

  Therefore, in the conventional hollow valve described above, unburned gas may increase at the time of engine start or the like, which may cause HC emission and fuel consumption deterioration.

  The present invention has been made in view of the above circumstances, and can quickly raise the temperature of the combustion chamber at the start of the internal combustion engine or during low-load operation, and the valve becomes excessively hot during high-load operation of the internal combustion engine. It aims at providing the hollow valve which can prevent becoming.

  (1) A hollow valve of the present invention that solves the above problems is a hollow valve that includes a shaft portion and an umbrella portion provided at a lower end of the shaft portion, and has a hollow hole from the umbrella portion to the shaft portion, A refrigerant made of a low-melting-point substance enclosed in the hollow hole, and disposed in the hollow hole, divides the hollow hole into an upper chamber and a lower chamber, and depends on the temperature in the hollow hole. A temperature-sensitive on-off valve device that opens and closes the communication port between the upper chamber and the lower chamber by opening and closing operations, and the temperature-sensitive on-off valve device raises the temperature in the hollow hole. The opening operation is performed in the process, the closing operation is performed in the process of lowering the temperature in the hollow hole, the opening operation set temperature at which the temperature-sensitive on-off valve device opens, and the temperature-sensitive on-off valve device is closed. The operation set temperature is a temperature within a temperature change range in the hollow hole, and the low melting point substance Characterized in that it is set to a temperature higher than the melting point.

  Here, the temperature change range in the hollow hole is a temperature change range in the hollow hole during the operation of the hollow valve.

  In this hollow valve, when the temperature in the hollow hole is lower than the opening operation set temperature of the temperature-sensitive on-off valve device and lower than the melting point of the low-melting substance constituting the refrigerant, the temperature-sensitive on-off valve device is in the hollow hole. The communication port between the upper chamber and the lower chamber is closed, and the refrigerant sealed in the hollow hole exists as a solid phase in the lower chamber in the hollow hole. And if the temperature in a hollow hole becomes higher than melting | fusing point of the low melting-point substance which comprises a refrigerant | coolant, a refrigerant | coolant will liquefy. At this time, if the temperature in the hollow hole does not reach the opening operation set temperature, the temperature-sensitive on-off valve device still closes the communication port between the upper chamber and the lower chamber in the hollow hole. Therefore, the liquid-phase refrigerant existing in the lower chamber in the hollow hole does not move to the upper chamber in the hollow hole via the communication port, and the liquid-phase refrigerant is stirred in the entire hollow hole. Absent. Therefore, the heat flow through the stirring of the liquid phase refrigerant is interrupted in the middle without continuing to the upper end side of the valve shaft. As a result, heat can be prevented from being radiated from the valve guide, which is in contact with the upper end side of the valve shaft, to the head cooling water via the liquid phase refrigerant.

  Therefore, when the temperature of the combustion chamber is low, such as when the internal combustion engine is started, and the temperature in the hollow hole is lower than the set temperature for opening the temperature-sensitive on-off valve device, the shaft portion of the valve is interposed via the liquid-phase refrigerant. No heat is radiated from the upper end side to the valve guide and the head cooling water. As a result, the temperature of the combustion chamber can be quickly raised when the internal combustion engine is started or during low load operation.

  On the other hand, when the temperature in the hollow hole rises and reaches the opening operation set temperature of the temperature sensitive on / off valve device, the temperature sensitive on / off valve device opens the communication port between the upper chamber and the lower chamber in the hollow hole. Then, the liquid phase refrigerant that has already been liquefied and exists in the lower chamber in the hollow hole moves to the upper chamber in the hollow hole through the communication port simultaneously with the opening of the communication port, and the liquid phase refrigerant moves in the hollow hole. The whole is stirred. Therefore, a large heat flow is generated rapidly in order from the combustion chamber, the bubble umbrella, the liquid refrigerant, the valve shaft, the valve guide in contact with the upper end of the shaft, and the head cooling water.

  Therefore, when the temperature of the combustion chamber is high during high load operation of the internal combustion engine and the temperature in the hollow hole is higher than the set temperature for opening the temperature-sensitive on-off valve device, the liquid stirred in the entire hollow hole Heat is radiated from the upper end side of the valve shaft to the valve guide and the head cooling water via the phase refrigerant. Moreover, if the temperature in the hollow hole becomes higher than the opening operation set temperature of the temperature-sensitive on-off valve device, the heat dissipation occurs promptly. As a result, it is possible to reliably prevent the valve from becoming excessively hot during high load operation of the internal combustion engine.

  (2) The hollow valve of the present invention is the hollow valve according to the above (1), wherein the temperature-sensitive on-off valve device is formed of a shape memory alloy and opens and closes the communication port. A bias spring that biases the valve body in the closing direction, and the valve body opens by the shape recovery of the shape memory alloy that resists the biasing force of the bias spring, and at least a portion of the crystal The shape memory alloy whose structure is transformed into the martensite phase is characterized by performing a closing operation by being deformed by the biasing force of the bias spring.

  According to this configuration, the shape memory alloy constituting at least a part of the valve body is cooled until it becomes lower than the martensite transformation start temperature (Ms point: temperature at which transformation from the austenite phase to the martensite phase starts). Then, it becomes soft and easily deformed by the phase transformation from the austenite phase to the martensite phase. For this reason, the shape memory alloy in which at least a part of the crystal structure is transformed into the martensite phase is deformed by the biasing force of the bias spring in the temperature lowering process in which the temperature in the hollow hole is lower than the martensite transformation start temperature. The valve body closes.

  On the other hand, the shape memory alloy returns to the shape before deformation and becomes hard due to the reverse transformation from the martensite phase to the austenite phase. For this reason, the temperature in the hollow hole is higher than the reverse transformation start temperature (As point: the temperature at which reverse transformation from the martensite phase to the austenite phase starts) against the bias spring biasing force. When the shape memory alloy constituting at least a part of the valve body recovers its shape, the valve body opens.

  (3) The hollow bulb according to the present invention is characterized in that, in the hollow bulb according to any one of the above items (1) to (2), the melting point of the low melting point substance is less than 65 ° C.

  According to this structure, if the temperature in a hollow hole will be 65 degreeC or more, a refrigerant | coolant will be in a liquid state. For this reason, even if the temperature in the hollow hole becomes 65 ° C. or higher, the heat radiation from the valve does not increase due to the high heat conduction action through the solid refrigerant having high thermal conductivity.

  (4) The hollow bulb according to the present invention is characterized in that, in the hollow bulb according to any one of the above items (1) to (3), the low-melting-point substance is made of an Na—K alloy.

  According to this structure, if the K content in the Na—K alloy is increased, the melting point of the low melting point substance can be lowered. Therefore, the melting point of the low melting point substance can be easily adjusted by changing the K content in the Na-K alloy.

  (5) The hollow bulb of the present invention is characterized in that, in the hollow bulb described in the above item (4), the low melting point substance has a melting point of 40 ° C. or higher.

  As described above, as the K content in the Na—K alloy increases, the melting point of the low melting point material decreases. On the other hand, if the K content in the Na—K alloy is increased, the thermal conductivity when the Na—K alloy is in a liquid state is lowered. Then, when a low melting point material made of Na—K alloy is adopted as the refrigerant, if the K content in the Na—K alloy is increased in order to lower the melting point of the low melting point material, the heat exchange action by stirring of the liquid phase refrigerant Becomes smaller. In that respect, if the melting point of the low melting point material made of the Na—K alloy is 40 ° C. or more, a sufficient heat exchange effect by agitation of the liquid phase refrigerant is exhibited.

  (6) The hollow valve of the present invention is the hollow valve according to any one of (1) to (5) above, wherein the open operation set temperature and the close operation set temperature are 70 ° C. ± 5 ° C. There is a special feature.

  According to this configuration, when the temperature in the hollow hole is in the range of 70 ° C. ± 5 ° C., the temperature-sensitive on-off valve device performs an opening operation and a closing operation. For this reason, if the temperature in the hollow hole is at least 65 ° C. or more, the temperature-sensitive on-off valve device opens, and the heat exchange action by stirring of the liquid-phase refrigerant is exhibited.

  Therefore, according to the hollow valve of the present invention, the temperature of the combustion chamber can be quickly raised when the internal combustion engine is started or during low load operation, and the valve is prevented from becoming excessively hot during high load operation of the internal combustion engine. be able to.

  Therefore, it becomes possible to suppress deterioration of HC emission and fuel consumption due to an increase in unburned gas at the time of starting the engine. Further, it becomes possible to suppress the thermal damage of the valve.

  Hereinafter, embodiments of the hollow valve of the present invention will be described in detail. The embodiment to be described is merely one embodiment, and the hollow valve of the present invention is not limited to the following embodiment. The hollow valve of the present invention can be implemented in various forms with modifications and improvements that can be made by those skilled in the art without departing from the scope of the present invention.

(Embodiment 1)
The hollow valve of the present embodiment shown in FIGS. 1 to 3 includes a shaft portion 1 and an umbrella portion 2 connected to the lower end of the shaft portion 1, and a hollow hole formed from the umbrella portion 2 to the shaft portion 1. 3.

  The hollow valve includes a stem body 10 that forms an upper end portion and an intermediate portion of the shaft portion 1, an umbrella body 20 that forms a lower end portion of the shaft portion 1 and an umbrella portion 2, and a lid that forms the lower end surface of the umbrella body 20. The body 30, the temperature-sensitive on-off valve device 40 accommodated in the hollow hole 3, and the refrigerant 50 sealed in the hollow hole 3 are used as constituent elements.

  The stem body 10, the umbrella body 20, and the lid body 30 are all made of heat resistant steel. The stem body 10 is formed with a hole 10 a extending from the lower end surface of the stem body 10 to the vicinity of the upper end portion of the stem body 10. A concave step 10b having an inner diameter larger than the inner diameter of the hole 10a is formed on the inner peripheral surface of the lower end portion of the stem body. The umbrella body 20 is formed with a through hole 20a penetrating from the lower end surface to the upper end surface.

  The stem body 10 and the umbrella body 20 are joined by welding after holding the temperature-sensitive on-off valve device 40 in the recessed step portion 10b of the stem body 10. The umbrella body 20 and the lid body 30 are joined by welding after joining the stem body 10 and the umbrella body 20 and putting the coolant 50 into the hollow hole 3.

  The refrigerant 50 is made of a low melting point material. As the low melting point substance, a low melting point alloy or a low melting point compound can be used.

  As the low melting point material used for the refrigerant 50, it is preferable to use a material having a melting point of less than 65 ° C. When a low-melting-point substance having a melting point of 65 ° C. or higher is used for the refrigerant 50, the refrigerant 50 is a solid phase that has higher thermal conductivity than the liquid phase even when the temperature in the hollow hole 3 becomes 65 ° C. or higher. Due to the high thermal conductivity through the solid-state refrigerant 50 with high conductivity, heat radiation from the valve is increased.

  Examples of the low melting point alloy having a melting point of less than 65 ° C. include a Na—K alloy, a Bi—Pb alloy, and a Bi—Sn alloy. Bi-Pb-based alloys include Bi-Pb-Sn-Cd-In alloys (for example, Bi-23% Pb-8% Sn-5% Cd-19% In alloys having a melting point of 19 ° C.) and Bi-Pb- An Sn—Cd alloy (for example, a Bi-25% Pb-13% Sn-13% Cd alloy having a melting point of 61 ° C.) can be given. As a Bi—Sn alloy, a Bi—Sn—Pb—In alloy ( For example, a Bi-19% Sn-17% Pb-11% In alloy having a melting point of 60 ° C. can be used. Among these alloys, it is preferable to use a Na-K alloy whose melting point can be easily adjusted by changing the K content.

  When the K content in the Na-K alloy is, for example, 17% by mass, the melting point is 65 ° C., when it is 25% by mass, the melting point is 50 ° C., and when it is 32% by mass, the melting point is 40 ° C., and 44% by mass. %, The melting point is 19 ° C.

  For this reason, it is preferable that the K content in the Na—K alloy is more than 17% by mass in order to make the melting point less than 65 ° C.

  On the other hand, as the low melting point material used for the refrigerant 50, it is preferable to use a material having a melting point of 20 ° C. (room temperature) or more. This is because the low melting point material constituting the refrigerant 50 is in a solid phase before the internal combustion engine is started and the low melting point material is melted after the internal combustion engine is started.

  For this reason, it is preferable that K content in Na-K alloy shall be 43 mass% or less so that melting | fusing point may be 20 degreeC or more.

  Moreover, when there is too much K content in a Na-K alloy, when it will be in a liquid phase, thermal conductivity will become low too much. For this reason, it is more preferable that the K content in the Na-K alloy is 25% by mass or less from the viewpoint of maintaining high thermal conductivity when the liquid phase is reached.

  The hollow hole 3 is divided into an upper chamber 3a and a lower chamber 3b by a temperature sensitive opening / closing valve device 40 accommodated in the hollow hole 3 in the lower region of the shaft portion 1. The temperature-sensitive on-off valve device 40 opens and closes the communication port 41a between the upper chamber 3a and the lower chamber 3b by performing an opening operation and a closing operation according to the temperature in the hollow hole 3.

  The temperature-sensitive on-off valve device 40 includes a bottomed cylindrical casing 41, a valve body 42, a Ni-Ti spring 43, a bias spring 44, and a washer 45 as constituent elements. The valve body 42 and the Ni-Ti spring 43 constitute a valve body in the present invention.

  Both the housing 41 and the valve body 42 are made of heat resistant steel. The washer 45 is made of stainless steel (SUS304 or the like). The bias spring 44 is made of stainless steel (SUS304 or the like) or spring steel (SWP-B or the like). One end of the Ni—Ti spring 43 is fixed to the washer 45, and the other end of the Ni—Ti spring 43 is fixed to the valve body 42. One end of the bias spring 44 is fixed to the washer 45, and the other end of the bias spring 44 is fixed to the valve body 42. The housing 41 and the washer 44 are joined by an adhesive or the like.

  The upper wall of the housing 41 is provided with a communication port 41a that allows the upper chamber 3a and the lower chamber 3b of the hollow hole 3 to communicate with each other. The communication port 41a is opened and closed by the valve body 42. The valve main body 42 is always urged by a bias spring 44 in the closing direction (direction in which the communication port 41a is closed). The washer 45 has a through hole 45a. For this reason, when the communication port 41a is opened, the upper chamber 3a and the lower chamber 3b in the hollow hole 3 communicate with each other through the communication port 41a and the through hole 45a of the washer 45.

  The Ni—Ti spring 43 is made of a Ni—Ti alloy as a shape memory alloy. The Ni-Ti alloy can adjust the phase transformation temperature by changing the Ni content.

  For example, by setting the Ni content in the Ni—Ti alloy to 54.8 to 55.1 mass%, the shape recovery temperature (Af point: reverse transformation end temperature from martensite phase to austenite phase) is set to 70 ° C. be able to. Moreover, shape recovery temperature can be 65 degreeC because Ni content in a Ni-Ti alloy shall be 54.9-55.2 mass%, and Ni content in a Ni-Ti alloy can be 54.7- By setting it as 55.0 mass%, shape recovery temperature (Af point) can be 75 degreeC.

  Here, the opening operation set temperature at which the temperature sensitive on / off valve device 40 performs the opening operation and the closing operation set temperature at which the temperature sensitive on / off valve device 40 performs the closing operation are the temperature changes in the hollow hole 3 during the operation of the hollow valve. The temperature is within a range (range from room temperature (20 ° C.) to 700 ° C.) and higher than the melting point of the low melting point substance of the refrigerant 50.

  Further, the Ni-Ti spring 43 made of a Ni-Ti alloy as a shape memory alloy has a shape shown in FIG. 3 showing a state in which the Ni-Ti spring 43 is contracted and the valve body 42 opens the communication port 41a. The shape is memorized. Further, the bias spring 44 has a longer spring length than the shape shown in FIG. 2 which shows a state in which the bias spring 44 extends and the valve body 42 closes the communication port 41a in a natural state where no external force is applied. (The bias spring 44 in the state shown in FIG. 2 is compressed by a predetermined amount). Furthermore, the spring force of the bias spring 44 is larger than the spring force of the Ni—Ti spring 43 when the Ni—Ti alloy is martensitic transformed.

  For this reason, the inside of the hollow hole 3 becomes a temperature higher than the shape recovery temperature of the Ni—Ti alloy (Af point: 70 ° C., for example), the Ni—Ti alloy reversely transforms into the austenite phase, and the Ni—Ti spring 43 is shaped. When the shape is restored to the memorized shape, the Ni-Ti spring 43 compresses the bias spring 44 against the spring force of the bias spring 44 and opens the valve body 42 (opens the communication port 41a). (See FIG. 3). That is, when the temperature in the hollow hole 3 rises to a temperature higher than the shape recovery temperature of the Ni—Ti alloy (Af point: 70 ° C., for example), the Ni—Ti spring 43 is caused by reverse transformation of the Ni—Ti alloy. The shape recovers, and thereby the valve body 42 opens and opens the communication port 41a.

  On the other hand, the temperature in the hollow hole 3 is equal to or lower than the martensitic transformation start temperature (Ms point: for example, 48 ° C.) of the Ni—Ti alloy, and the Ni—Ti alloy undergoes martensitic transformation so that at least a part of the Ni—Ti alloy is formed. When the martensite phase is soft, the Ni-Ti spring 43 has a smaller spring force than the bias spring 44, and the Ni-Ti spring 43 is stretched by the bias spring 44. As a result, the valve main body 42 is biased by the bias spring 44 and maintained in a closed state (a state in which the communication port 41a is closed) (see FIG. 2). That is, when the temperature in the hollow hole 3 falls to a temperature lower than the martensitic transformation start temperature (Ms point: 48 ° C., for example) of the Ni—Ti alloy, the Ni—Ti spring is caused by the martensitic transformation of the Ni—Ti alloy. As a result, the valve body 42 is closed by the biasing force of the bias spring 44 and the communication port 41a is closed.

  In this embodiment, the shape recovery temperature (Af point: for example, 70 ° C.) of the Ni—Ti alloy constituting the Ni—Ti spring 43 is the opening operation set temperature of the temperature sensitive on-off valve device 40. Further, the martensitic transformation start temperature (Ms point: 48 ° C., for example) of the Ni—Ti alloy constituting the Ni—Ti spring 43 becomes the closing operation set temperature of the temperature sensitive on-off valve device 40.

  Therefore, in the hollow valve of the present embodiment, when the temperature in the hollow hole 3 is lower than the opening operation set temperature of the temperature sensitive on-off valve device 40 and lower than the melting point of the low melting point material constituting the refrigerant 50, the temperature sensitive. The on-off valve device 40 closes the communication port 41 a between the upper chamber 3 a and the lower chamber 3 b in the hollow hole 3, and the refrigerant 50 sealed in the hollow hole 3 is a solid phase below the hollow hole 3. It exists in the chamber 3b. And if the temperature in the hollow hole 3 becomes higher than the melting point of the low melting point substance constituting the refrigerant 50, the refrigerant 50 is liquefied. At this time, if the temperature in the hollow hole 3 does not reach the opening operation set temperature, the temperature-sensitive on-off valve device 40 still closes the communication port 41a. For this reason, the liquid-phase refrigerant 50 existing in the lower chamber 3b in the hollow hole 3 does not move to the upper chamber 3a in the hollow hole 3 through the communication port 41a, and the liquid-phase refrigerant 50 is 3 is not agitated throughout. Therefore, the heat flow through the stirring of the liquid-phase refrigerant 50 is interrupted halfway without continuing to the upper end side of the valve shaft 1. As a result, heat can be prevented from being radiated to the head cooling water from the valve guide 6 (see FIG. 1) with which the upper end side of the valve shaft 1 contacts via the liquid phase refrigerant 50.

  Therefore, when the temperature of the combustion chamber is low at the time of starting the engine or the like, and therefore the temperature in the hollow hole 3 is lower than the opening operation set temperature of the temperature sensitive on-off valve device 40, the valve is connected via the liquid phase refrigerant 50. No heat is radiated from the upper end side of the shaft portion 1 to the valve guide 6 and the head cooling water. As a result, the temperature of the combustion chamber can be quickly raised when the engine is started or during low load operation.

  On the other hand, when the temperature in the hollow hole 3 rises and reaches the opening operation set temperature of the temperature sensitive on / off valve device 40, the temperature sensitive on / off valve device 40 opens the communication port 41a. Then, the liquid-phase refrigerant 50 already liquefied and existing in the lower chamber 3b in the hollow hole 3 moves to the upper chamber 3a in the hollow hole 3 through the communication port 41a simultaneously with the opening of the communication port 41a. The liquid-phase refrigerant 50 is stirred throughout the hollow hole 3. Therefore, a large heat flow is generated rapidly in order from the combustion chamber, the bubble umbrella 2, the liquid phase refrigerant 50, the valve shaft 1, the valve guide 6 in contact with the upper end of the shaft 1, and the head cooling water.

  Therefore, when the temperature of the combustion chamber is high, such as during high-load operation of the engine, and therefore the temperature in the hollow hole 3 is higher than the opening operation set temperature of the temperature sensitive on-off valve device 40, the entire hollow hole 3 is agitated. Heat is radiated from the upper end side of the valve shaft 1 to the valve guide 6 and the head cooling water through the liquid phase refrigerant 50. Moreover, if the temperature in the hollow hole 3 becomes higher than the opening operation set temperature of the temperature-sensitive on-off valve device 40, the heat dissipation occurs promptly. As a result, it is possible to reliably prevent the valve from becoming excessively hot during high engine load operation.

(Embodiment 2)
The hollow valve of the present embodiment shown in FIGS. 4 to 7 is obtained by changing the structure of the temperature-sensitive on-off valve device 40 in the hollow valve of the first embodiment.

  The temperature-sensitive on-off valve device 40 according to the second embodiment includes a bottomed tubular casing 41, a Ni-Ti valve body 46, a bias spring 44, and a washer 45 as constituent elements. That is, the temperature-sensitive on-off valve device 40 in the second embodiment employs a Ni-Ti valve body 46 instead of the valve body 42 and the Ni-Ti spring 43 of the temperature-sensitive on-off valve device 40 in the first embodiment.

  The Ni-Ti valve body 46 has a substantially truncated cone shape whose outer diameter is gradually reduced. The Ni-Ti valve body 46 has a top wall 46a that opens and closes the communication port 41a. Moreover, the Ni-Ti valve body 46 has a plurality of through holes 46b on the side wall for communicating the inside and outside (upper and lower) of the Ni-Ti valve body 46. For this reason, when the top wall 46a of the Ni-Ti valve body 46 opens the communication port 41a, the plurality of through holes 46b of the Ni-Ti valve body 46, the through holes 45a of the washer 45, and the communication port 41a are used. Thus, the upper chamber 3a and the lower chamber 3b in the hollow hole 3 communicate with each other.

  As the shape memory alloy constituting the Ni—Ti valve body 46, the same one as described in the first embodiment can be used.

  Further, the Ni—Ti valve element 46 made of a Ni—Ti alloy as a shape memory alloy is shown in FIG. 5 showing a state in which the Ni—Ti valve element 46 is contracted and the top wall 46a opens the communication port 41a. The shape is memorized. Moreover, the bias spring 44 is longer than the shape shown in FIG. 4 which shows the state which the Ni-Ti valve body 46 is extended and the top wall 46a has closed the communicating port 41a in the natural state to which the external force is not provided. It has a spring length (the bias spring 44 in the state shown in FIG. 4 is compressed by a predetermined amount). Further, the spring force of the bias spring 44 is larger than the generated force of the Ni—Ti valve body 46 when the Ni—Ti alloy is martensitic transformed.

  For this reason, the inside of the hollow hole 3 becomes a temperature higher than the shape recovery temperature of the Ni—Ti alloy (Af point: 70 ° C., for example), the Ni—Ti alloy is reversely transformed into the austenite phase, and the Ni—Ti valve body 46 is formed. When the shape is restored to the shape memorized, the Ni-Ti valve body 46 opens the communication port 41a against the spring force of the bias spring 44 (see FIG. 5). That is, when the temperature in the hollow hole 3 rises to a temperature higher than the shape recovery temperature of the Ni—Ti alloy (Af point: 70 ° C., for example), the Ni—Ti valve body 46 is caused by reverse transformation of the Ni—Ti alloy. As a result, the Ni-Ti valve body 46 opens to open the communication port 41a.

  On the other hand, the temperature of the hollow hole 3 is not higher than the martensitic transformation start temperature (Ms point: 48 ° C., for example) of the Ni—Ti alloy, the Ni—Ti alloy undergoes martensitic transformation, and at least a part of the Ni—Ti alloy is martensitic. When the site phase is soft, the generated force of the Ni—Ti valve body 46 is smaller than the spring force of the bias spring 44, and the Ni—Ti valve body 46 is expanded by the bias spring 44. As a result, the Ni-Ti valve body 46 is biased by the bias spring 44 and closes the communication port 41a. That is, when the temperature in the hollow hole 3 falls to a temperature lower than the martensitic transformation start temperature (Ms point: 48 ° C., for example) of the Ni—Ti alloy, the Ni—Ti valve is caused by the martensitic transformation of the Ni—Ti alloy. The body 46 becomes soft, and as a result, the Ni-Ti valve body 46 is closed by the biasing force of the bias spring 44 to close the communication port 41a.

  Since other configurations and operational effects are the same as those of the first embodiment, the description thereof is incorporated and omitted.

1 is a cross-sectional view schematically showing the overall configuration of a hollow valve according to Embodiment 1. FIG. It is sectional drawing when the structure of the temperature sensitive on-off valve apparatus in the hollow valve which concerns on Embodiment 1 is shown, and a temperature sensitive on-off valve apparatus is in a closed state. It is sectional drawing when the structure of the temperature sensitive on-off valve apparatus in the hollow valve which concerns on Embodiment 1 is shown, and a temperature sensitive on-off valve apparatus is in an open state. It is sectional drawing when the structure of the temperature sensitive on-off valve apparatus in the hollow valve which concerns on Embodiment 2 is shown, and a temperature sensitive on-off valve apparatus is in a closed state. It is sectional drawing when the structure of the temperature sensitive on-off valve apparatus in the hollow valve which concerns on Embodiment 2 is shown, and a temperature sensitive on-off valve apparatus is in an open state. It is a perspective view which shows the valve body which is a component of the temperature sensitive on-off valve apparatus in the hollow valve which concerns on Embodiment 2. FIG. It is a top view which shows the valve body which is a component of the temperature sensitive on-off valve apparatus in the hollow valve which concerns on Embodiment 2. FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Shaft part 2 ... Umbrella part 3 ... Hollow hole 3a ... Upper chamber 3b ... Lower chamber 40 ... Temperature sensitive opening / closing valve apparatus 50 ... Refrigerant 41a ... Communication port 42 ... Valve body (valve body) 43 ... Ni-Ti spring (valve) body)
44 ... Bias spring 46 ... Ni-Ti valve body

Claims (6)

A hollow valve comprising a shaft portion and an umbrella portion provided at a lower end of the shaft portion, and having a hollow hole from the umbrella portion to the shaft portion,
A refrigerant made of a low-melting-point substance enclosed in the hollow hole;
The upper chamber and the lower chamber are disposed by being disposed in the hollow hole, dividing the hollow hole into an upper chamber and a lower chamber, and performing an opening operation and a closing operation in accordance with the temperature in the hollow hole. A temperature-sensitive on-off valve device for opening and closing the communication port of
The temperature sensitive on-off valve device performs an opening operation in the process of raising the temperature in the hollow hole, and performs a closing operation in the process of lowering the temperature in the hollow hole,
The open operation set temperature at which the temperature sensitive on / off valve device performs an open operation and the close operation set temperature at which the temperature sensitive on / off valve device performs a close operation are a temperature within a temperature change range in the hollow hole and the low melting point A hollow valve characterized by being set at a temperature higher than the melting point of the substance. The temperature-sensitive on-off valve device comprises a valve body that is at least partially made of a shape memory alloy and opens and closes the communication port, and a bias spring that biases the valve body in a closing direction,
The valve body performs the opening operation by shape recovery of the shape memory alloy that resists the biasing force of the bias spring, and the shape memory alloy in which at least a part of the crystal structure is transformed into a martensite phase. The hollow valve according to claim 1, wherein the closing operation is performed by being deformed by a biasing force of the bias spring.   The hollow valve according to any one of claims 1 to 2, wherein the low-melting-point substance has a melting point of less than 65 ° C.   The hollow valve according to any one of claims 1 to 3, wherein the low melting point material is made of a Na-K alloy.   The hollow valve according to claim 4, wherein the low-melting-point substance has a melting point of 40 ° C. or higher.   The hollow valve according to any one of claims 1 to 5, wherein the opening operation setting temperature and the closing operation setting temperature are 70 ° C ± 5 ° C.

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