JP3357774B2 - External combustion engine piston - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a piston for an external combustion engine, such as a Vilmier cycle or a Stirling cycle, used for cooling and heating, hot water supply, power, and the like.

[0002]

2. Description of the Related Art Some pistons of this kind of external combustion engine have a hollow portion in which the inside of the piston is hollow in order to reduce the load on the piston driving portion and the material cost of the piston. However, if a hollow part is formed in the piston,
Heat convection and radiation may occur, and various proposals have been made to reduce heat loss.

FIG. 6 is a longitudinal sectional view of a Vilmier cycle as an external combustion engine.

In FIG. 1, a Vilmier cycle includes a high-temperature side piston (displacer) 1, a low-temperature side piston (displacer) 2, a high-temperature side cylinder 3 containing the high-temperature side piston (displacer) 1, and a low-temperature side piston (display). Sir) Low-temperature side cylinder 4 containing 2
And a high temperature side piston (displacer)
1 is connected to a piston rod 5 disposed at a right angle to a low temperature side piston (displacer) 2 and performs reciprocating motion. The low temperature side piston (displacer) 2 is connected to a piston rod 6 and reciprocates. ing.

A high temperature chamber 3a is provided in front of the high temperature cylinder 3 and a high temperature heat exchanger 7 communicating with the high temperature chamber 3a is heated by an external heat source such as a heater. A high-temperature-side regenerator 9 and a medium-temperature-side heat exchanger 10 are interposed between the distal end of the high-temperature-side heat exchanger 7 and the medium-temperature chamber 3b disposed behind the high-temperature-side cylinder 3. Further, a low-temperature chamber 4a is provided in front of the low-temperature side cylinder 4, and a low-temperature side heat exchanger 11 and a low-temperature side heat exchanger 11 are provided between the low-temperature side 4a and the medium-temperature chamber 4b disposed behind the low-temperature side cylinder 4. A regenerator 12 and a middle-temperature side heat exchanger 13 are interposed. Reference numeral 14 denotes a communication path as a gas flow path that connects the middle temperature chamber 3b and the middle temperature chamber 4b.

On the other hand, two connecting rods 16, 17 connected to the piston rod 5 and the piston rod 6, which are disposed at right angles, a crankshaft 18, and a balance weight 1
9 constitute a crank mechanism 15 and a crank case 20.
It is built in. On the shaft of the crankshaft 18, a drive motor (not shown) is directly connected to the crankshaft 18, and the high-temperature side piston (displacer) 1 and the low-temperature side piston (displacer) 2 are about 90 degrees by the crank mechanism 15.
It is configured to reciprocate with a phase difference of °.

In the above configuration, first, on the low temperature side, the low temperature side piston (displacer) 2 reciprocates periodically, and when it moves to the left in the figure (from bottom dead center to top dead center). The working gas such as helium inside the low temperature chamber 4a flows into the medium temperature chamber 4b via the low temperature side heat exchanger 11, the low temperature side regenerator 12 and the medium temperature side heat exchanger 13. At this time, the moved working gas receives heat stored in the low-temperature side regenerator 12 and increases the temperature. When the temperature rises, the volume of the working gas increases due to the expansion of the working gas, and a portion of the working gas fills the middle temperature chamber 4b. Therefore, the remaining working gas that does not enter the middle temperature chamber 4b moves to the middle temperature chamber 3b through the communication path 14. I do. Thereby, the pressure of the working gas in the middle temperature chamber 3b increases. Then, the heat is released from the middle-temperature side heat exchanger 10 to the outside, and the raised temperature is restored.

In response to this, when the high temperature side piston (displacer) 1 descends in the figure (falls from the top dead center to the bottom dead center), the working gas inside the medium temperature chamber 3b is changed to the medium temperature side heat exchanger 10 And flows into the high temperature chamber 3a via the high temperature side regenerator 9. In this process, the working gas that has passed through the high-temperature side regenerator 9 receives heat from the high-temperature side regenerator 9 and raises the temperature. When the temperature of the working gas in the high-temperature chamber 3a rises,
The working gas expands, a part of the working gas fills the high-temperature chamber 3a, and the remaining working gas is prevented from flowing into the high-temperature chamber 3a and moves to the middle-temperature chamber 4b through the communication path 14. As a result, the temperature and pressure of the working gas in the medium temperature chamber 4b into which the working gas has flowed are increased. Therefore, the heat is released from the middle-temperature side heat exchanger 13 to the outside, and the raised temperature is restored.

On the other hand, when the low temperature side piston (displacer) 2 reciprocates periodically and moves rightward in the figure (from top dead center to bottom dead center), the working gas inside the medium temperature chamber 4b is moved. Flows into the low temperature chamber 4a via the medium temperature side heat exchanger 13, the low temperature side regenerator 12, and the low temperature side heat exchanger 11. In this case, the moved working gas is supplied to the low-temperature side regenerator 1.
Store heat in 2 and lower the temperature. As a result, the working gas shrinks, and a part of the working gas in the high temperature chamber 3a passes through each of the heat exchangers and the communication passage 14 to compensate for the insufficient volume.
Move to. As a result, the working gas in the high-temperature chamber 3a, whose temperature and pressure have been reduced due to the outflow of the working gas, is transferred to the high-temperature side heat exchanger 7a.
Absorb heat from and restore temperature.

On the other hand, when the high temperature side piston (displacer) 1 rises in the figure (goes from the bottom dead center to the top dead center), the working gas inside the high temperature chamber 3a is discharged to the high temperature side regenerator 9 and the high temperature side. Medium-temperature room 3 via side heat exchanger 10
b. The moved working gas stores heat in the high temperature side regenerator 9 and lowers the temperature. As a result, the working gas contracts, and a part of the working gas in the low temperature chamber 4a moves to the middle temperature chamber 3b through each of the heat exchangers and the communication passage 14 to make up for the insufficient volume. As a result, the working gas in the low-temperature chamber 4a, whose temperature and pressure have decreased with the outflow of the working gas, absorbs heat from the outside via the low-temperature side heat exchanger 11 and returns the temperature to the original state.

The pipe exiting from the intermediate temperature side heat exchanger 10 is returned to the intermediate temperature side heat exchanger 10 via an unillustrated outdoor (or indoor) side heat exchanger, a circulation pump, and an intermediate temperature side heat exchanger 13. The pipes coming out of the low-temperature side heat exchanger 11 return to the low-temperature side heat exchanger 11 via an indoor (or outdoor) side heat exchanger (not shown) and a circulating pump. Or heating).

Reference numerals 21 and 22 denote communication holes, 23 is a partition plate disposed in the high temperature side piston (displacer) 1, the partition plate 23 is formed with a hole 23a, and 24 is a low temperature side piston (display). Sir)
A hole 24a is formed.

Next, a chiller using a Stirling cycle as another example of the external combustion engine will be described with reference to FIG.

The Stirling cycle mainly includes an expander 26, a compressor 27, and a driving chamber 28.
The expander 26 includes an expansion cylinder 29 and an expansion piston 30 reciprocating in the cylinder. Similarly, the compressor 27 includes a compression cylinder 31 and a compression piston 32 reciprocating in the cylinder.

Expansion piston 30 and compression piston 32
Are connected to a crank mechanism 35 disposed inside the drive chamber 28 via piston rods 33 and 34, respectively.
It is driven with a phase difference of 0 °.

A regenerator 36, which is a regenerator, is disposed between the periphery of the expansion cylinder 29 of the expander 26 and the container, and through the regenerator 36, an expansion space 37 formed in front of the expansion piston 30 and a front of the compression piston 32. A gas flow path 39 communicates with a compression space 38 generated during the refrigerating cycle to move the gas during the refrigeration cycle.

On the other hand, the space on the back pressure side of the expansion piston 30 and the compression piston 32 is connected by a gas flow passage 40 in order to prevent loss of work of the piston. A radiation fin 42 is arranged on the outer peripheral surface of the container of the compressor 27. Reference numerals 44 and 45 denote buffer chambers.
Reference numeral 7 denotes a communication hole.

In this configuration, when the crank mechanism 35 of the drive chamber 28 is driven by the rotation of a drive motor (not shown), the compression piston 3 in the compression cylinder 31 of the compressor 27 is driven.
2 moves to the compression space 38 side, and the refrigerant gas as the hardly liquefiable working gas such as helium filling the compression space 38 is compressed.

The compressed refrigerant gas flows into the regenerator 36 from the gas passage 39. The refrigerant gas flowing into the heat accumulator 36 is cooled by a material having a large specific heat, for example, a heat storage material formed of a wire mesh or sphere of copper or lead, and flows into the expansion space 37 of the expander 26 to be in a high pressure state. .

Thereafter, the expansion piston 30 in the expansion cylinder 29 of the expander 26 descends with a phase difference of about 90 ° from the compression piston 32. As a result, the expansion space 37 is suddenly expanded, and the pressure of the refrigerant gas drops rapidly, so that the temperature of the refrigerant gas becomes low.

Eventually, when the expansion piston 30 starts to rise and the compression piston 32 retreats, low-temperature refrigerant gas passes through the heat storage 36, passes through the gas flow path 39, and passes through the compression space 3.
Returned to 8. At this time, in the heat storage 36, the heat storage material is cooled and cold heat is stored.

By the above-described process, one heat cycle is completed, and this process is repeated by the crank mechanism 35. As a result, the temperature of the refrigeration generator, which is the expansion space 37, and the temperature of the regenerator 36 gradually decrease. The temperature of the refrigerant gas in the refrigeration generator becomes low, and the generated cold heat can be taken out and used.

The high-temperature side piston (displacer) 1 and low-temperature side piston (displacer) 2 described with reference to FIG. 6 or the expansion piston 30 and the compression piston 32 described with reference to FIG. However, the burden, cost and weight of the crank mechanisms 15 and 35 can be reduced. For this reason, in the case shown in FIG. 6, since the pressure outside the piston becomes considerably high, it is necessary to fill a high-pressure gas inside the piston. However, it is difficult to seal a high-pressure gas inside the piston in advance in terms of assembly work. For this reason, conventionally, the piston rods 5 and 6 are provided with communication holes 21 and 22 as hollow gas passages therein so as to communicate with the inside of the drive chamber, and after assembly, a high-pressure gas is sealed in the inside of the drive chamber from the outside to thereby provide a piston. The insides of 1 and 2 were kept at high pressure.

In this case, a new problem arises in that convection and radiation occur in the hollow portion of the piston and heat loss is large.

To solve this problem, as shown in FIGS. 8 and 9, the piston 55 includes a partition plate 58 having a communication hole 58a in a hollow portion 57 of a cylindrical body 56 and a partition plate 59 having a communication hole 59a. In the case of FIG. 8, a communication hole 60 a is provided in the lid 60, and the piston rod 61 is connected to the lid 60. In the case of FIG. 9, the piston rod 6
1 is provided with a communication hole 61a.

[0026]

However, in the piston 55 as shown in FIGS. 8 and 9, the partition plate 58,
59, radiation and convection of the hollow portion 57 can be prevented to some extent by dividing into three hollow portions 57a, 57b, 57c, but there are still three hollow portions 57a, 57b, 57c,
The partition plate 58 has a communication hole 58a, and the partition plate 59 has a communication hole 59a. Further, in FIG. 8, the communication hole 6
In FIG. 9, the piston rod 61 has a communication hole 6a.
There is a problem that radiation and convection occur in these spaces, heat loss is large, and thermal efficiency is reduced.

Accordingly, an object of the present invention is to solve the above-mentioned problems and to provide a piston of an external combustion engine having high thermal efficiency.

[0028]

According to a first aspect of the present invention, there is provided a piston having a hollow portion inside, a communication hole communicating from the hollow portion to the outside, and a piston connected to a driving source via a piston rod. In the piston of the external combustion engine equipped, while the hollow portion is filled with a member with low thermal conductivity,
A ventilation member for preventing a member having low thermal conductivity from leaking to the outside is provided in the communication hole.

According to a second aspect of the present invention, in a piston of an external combustion engine having a hollow portion inside and a piston communicating with a driving chamber through a communication hole formed in a piston rod, the hollow portion has a thermal conductivity. In this case, a member having a low thermal conductivity is provided in the communication hole while a member having a low thermal conductivity is prevented from leaking to the outside.

According to a third aspect of the present invention, in a piston of an external combustion engine having a hollow portion inside and having a piston communicating with a drive chamber via a piston rod, the hollow portion is filled with a member having low thermal conductivity. In addition, a permeable member for preventing a member having a low thermal conductivity from leaking outside is arranged in the hollow portion.

According to a fourth aspect of the present invention, in the piston of the external combustion engine according to the third aspect, the permeable member is made of a member having low thermal conductivity or a permeable metal.

According to a fifth aspect of the present invention, in the piston of the external combustion engine according to the third aspect, the permeable member is arranged so as to surround the entirety of the member having a low thermal conductivity filled in the hollow portion. It was done.

[0033]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a cross-sectional view of a piston according to a first embodiment of the present invention. A piston 55A includes a high-temperature side piston (displacer) 1 and a low-temperature side piston (display) of the Vilmier cycle shown in FIG. 2), and also applicable to the expansion piston 30 and the compression piston 32 of the Stirling refrigerator shown in FIG.

As shown in FIG. 1, the piston 55A is characterized in that a hollow portion 57 is filled with a member 62 having a low thermal conductivity and a permeable member 63 is disposed in a communication hole 60a of a lid 60. Have.

The members 62 having a low thermal conductivity include:
For example, ceramic fibers, glass fibers, rock wool, etc., which are generally referred to as heat insulating materials in the form of bulk (cotton), styrofoam or felt (strips) obtained by molding them, or powder of heat insulating materials are used. it can.

As described above, when the hollow portion 57 of the piston 55A is filled with the member 62 having a low thermal conductivity, the movement of the gas in the hollow portion 57 is prevented by the member 62 having a low thermal conductivity. . Therefore, even if a temperature difference occurs between the outside and the inside of the cylindrical body 56 of the piston 55A, convection is prevented from occurring in the hollow portion 57.

Further, the transmission of radiant heat is prevented by the member 62 having a low thermal conductivity filled in the hollow portion 57. Thereby, the hollow portion 5 of the piston 55
7, the heat loss due to heat convection and radiation is greatly reduced. In addition, the hollow portion 57 is formed by the member 62 having low thermal conductivity.
Is prevented from conducting heat directly.

On the other hand, if the low thermal conductivity member 62 is filled and installed in the hollow portion 57 of the piston 55, the low thermal conductivity member 62 may leak from the communication hole 60a to an external buffer chamber or the like. In this case, the air-permeable member 63 disposed in the communication hole 60a prevents the member 62 having a low thermal conductivity from leaking to an external buffer chamber or the like. As a result,
While it is possible to eliminate the possibility of invading and affecting the members 62 having low thermal conductivity into the bearings and the seal portions and the like, thereby reducing the durability of each portion of the external combustion engine, the cylindrical body 56 against the external pressure can be eliminated.
The pressure in the hollow portion 57 can be adjusted so as to withstand the pressure, and in the case shown in FIG. 7, the work of the piston can be reduced. The permeable member 63 includes, for example, a sintered metal that is a porous metal.

For example, in the above-described Vilmier cycle shown in FIG. 6, the high-temperature side piston (displacer) 1 and the low-temperature side piston (displacer) 2 cause each part of the piston to move from high temperature to low temperature and from high pressure to low pressure. Is repeated. In such a case, the piston 55A
Although the temperature of each part of the cylindrical body 56 suddenly changes, the convection of gas or the transfer of heat by radiation is prevented in the hollow portion 57 by the member 62 having low thermal conductivity. The same applies to the freezer using the Stirling cycle shown in FIG.

As described above, according to the first embodiment of the present invention, the transfer of heat in the hollow portion 57 of the piston 55A is prevented while the hollow portion 57 of the piston 55A communicates with the buffer chamber. In addition, it is possible to prevent the member 62 having a low thermal conductivity from leaking out from the communication hole 60a, and to eliminate the possibility of reducing the durability of each part of the external combustion engine.

FIG. 2 is a sectional view of a piston according to a second embodiment of the present invention. In a piston 55B, a hollow member 57 is filled with a member 62 having a low thermal conductivity, while a piston rod 61 is mounted on a piston rod 61. The ventilation member 6 is provided in the communication hole 61a provided.
4 is arranged.

According to this configuration, first, the piston 55B
The movement of gas in the hollow portion 57 is prevented by the member 62 having a low thermal conductivity, the convection of the hollow portion 57 is reduced, and the transmission of radiant heat is prevented by the member 62 having a low thermal conductivity. The member 62 having low conductivity prevents direct heat conduction. And the breathable member 64
Accordingly, the member 62 having a low thermal conductivity is prevented from leaking from the hollow portion 57 to the driving chamber or the like while controlling the pressure in communication with the driving chamber or the like.

As described above, the temperature is cut off, the heat loss due to the piston 55B is greatly reduced, the thermal efficiency is improved, and the member 62 having a low thermal conductivity is driven while communicating with the drive chamber or the like by pressure. It is possible to eliminate the risk of leaking into a room or the like and reducing durability.

FIG. 3 is a sectional view of a piston of an external combustion engine according to a third embodiment of the present invention.
C is characterized in that the hollow portion 57 is filled with a member 62 having a low thermal conductivity, and a plate-shaped air-permeable member 65 is arranged so as to form a space 66 on the lid body 60 side.

According to this configuration, in addition to the operation of the second embodiment, the surface area of the air permeable member 65 is formed large, the pressure for sealing the driving chamber and the like can be sufficiently adjusted, and the heat conductivity is low. The member 62 eliminates the risk of the air-permeable member 65 being clogged.

FIG. 4 is a sectional view of a piston of an external combustion engine according to a fourth embodiment of the present invention.
D is characterized in that the hollow portion 57 is filled with a member 62 having a low heat conductivity, and a gas permeable member 67 having a low heat conductivity and air permeability is provided on the lid 60 side. Here, examples of the air-permeable member 67 include a long-fiber heat insulating material and a cloth heat insulating material.

According to this configuration, in addition to the operation of the second embodiment, the surface area of the gas permeable member 67 can be made large, the pressure for sealing with the drive chamber and the like can be adjusted, and the gas permeable member 67 Both the ventilation function and the function of preventing the member 62 having a low thermal conductivity from leaking outside can be sufficiently exhibited.

FIG. 5 is a sectional view of a piston of an external combustion engine showing a fifth embodiment of the present invention.
E is characterized in that the member 62 having low thermal conductivity is surrounded by the bag-shaped air-permeable member 68 and disposed in the hollow portion 57. Here, as the air permeable member 68, there is a cloth-like heat insulating material or the like.

According to this configuration, in addition to the operation of the second embodiment, the surface area of the gas permeable member 68 can be made large, the sealing pressure with the driving chamber and the like can be adjusted, and the gas permeable member 68 Both the ventilation function and the function of preventing the member 62 having a low thermal conductivity from leaking outside can be sufficiently exhibited.

[0051]

As described above, according to the first aspect of the present invention, a member having a low thermal conductivity is filled and installed in the hollow portion, and a permeable member is arranged in the communication hole, so that heat transfer in the hollow portion can be prevented. In addition, it is possible to prevent members having low thermal conductivity from leaking to the outside.

According to the second aspect of the present invention, since the hollow portion is filled with a member having a low thermal conductivity and the ventilation hole is disposed in the communication hole, the transfer of heat in the hollow portion can be prevented. In addition, it is possible to prevent a member having low thermal conductivity from leaking to the outside.

According to the third aspect of the present invention, since the air-permeable member is provided in the hollow portion and the surface area of the air-permeable member is larger than that of the second aspect, the air-permeable member is not clogged and the sealing pressure is reduced. Adjustment is sufficient.

According to the invention of claim 4, according to claim 3,
In addition to the effects described above, it is possible to appropriately adjust the sealing pressure and to prevent a member having a low thermal conductivity from leaking to the outside by using a gas-permeable member suitable for use conditions.

According to the invention of claim 5, according to claim 3,
In addition to the effect described above, a gas permeable member surrounding the whole of the member having low thermal conductivity is provided, so that the gas permeable function can be sufficiently exhibited by the large surface area.

[0056]

[Brief description of the drawings]

FIG. 1 is a sectional configuration diagram of a piston of an external combustion engine, showing a first embodiment of the present invention.

FIG. 2 is a cross-sectional configuration diagram of a piston of an external combustion engine showing a second embodiment of the present invention.

FIG. 3 is a cross-sectional configuration diagram of a piston of an external combustion engine showing a third embodiment of the present invention.

FIG. 4 is a sectional configuration diagram of a piston of an external combustion engine showing a fourth embodiment of the present invention.

FIG. 5 is a cross-sectional configuration diagram of a piston of an external combustion engine showing a fifth embodiment of the present invention.

FIG. 6 is a cross-sectional configuration diagram showing a Vilmier cycle as a conventional external combustion engine.

FIG. 7 is a sectional configuration diagram showing a conventional Stirling refrigerator as an external combustion engine.

FIG. 8 is a sectional view showing a first example of a conventional piston of an external combustion engine.

FIG. 9 is a sectional configuration diagram showing a second example of a conventional piston of an external combustion engine.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 High temperature side piston (displacer) 2 Low temperature side piston (displacer) 3 High temperature side cylinder 3a High temperature room 3b, 4b Medium temperature room 4 Low temperature side cylinder 4a Low temperature room 5, 6, 33, 34, 61 Piston rod 9 High temperature side regeneration Apparatus 10, 13 Medium-temperature side heat exchanger 11 Low-temperature side heat exchanger 12 Low-temperature side regenerator 14 Communication path 26 Expander 27 Compressor 28 Drive chamber 29 Expansion cylinder 30 Expansion piston 31 Compression cylinder 32 Compression piston 55 Piston 56 Cylindrical body 57 Hollow portion 60 Lid 62 Member with low thermal conductivity 63 Air permeable member 66 Space

Continuation of front page (56) References JP-A-58-96148 (JP, A) JP-A-58-65957 (JP, A) JP-A-5-248719 (JP, A) JP-A-9-96455 (JP, A) , A) Hikaru 1-124063 (JP, U) (58) Fields investigated (Int. Cl. ⁷ , DB name) F25B 9/14 510 F25B 9/14 520 F02G 1/053

Claims (5)

(57) [Claims] 1. A piston for an external combustion engine having a hollow portion inside, a communication hole communicating from the hollow portion to the outside, and a piston connected to a drive source via a piston rod. While filling with low thermal conductivity members
A piston for an external combustion engine, wherein a ventilation member for preventing the member having a low thermal conductivity from leaking outside is disposed in the communication hole. 2. A piston of an external combustion engine having a hollow inside and a piston communicating with a drive chamber via a communication hole formed in a piston rod, wherein a member having a low thermal conductivity is provided in the hollow. While charging installation,
A piston for an external combustion engine, wherein a ventilation member for preventing the member having a low thermal conductivity from leaking to the outside is arranged in the communication hole. 3. A piston of an external combustion engine having a hollow portion inside and having a piston communicating with a drive chamber via a piston rod, wherein the hollow portion is filled with a member having low thermal conductivity, and the hollow portion is filled with a member having a low thermal conductivity. A piston for an external combustion engine, wherein a permeable member for preventing the member having a low thermal conductivity from leaking outside is disposed in the portion. 4. The piston of an external combustion engine according to claim 3, wherein the permeable member is made of a member having low thermal conductivity or a permeable metal. 5. The piston of an external combustion engine according to claim 3, wherein the permeable member is arranged so as to surround the entirety of the member having a low thermal conductivity filled in the hollow portion.