WO2010067728A1 - ピストンの気体潤滑構造およびスターリングエンジン - Google Patents
ピストンの気体潤滑構造およびスターリングエンジン Download PDFInfo
- Publication number
- WO2010067728A1 WO2010067728A1 PCT/JP2009/070143 JP2009070143W WO2010067728A1 WO 2010067728 A1 WO2010067728 A1 WO 2010067728A1 JP 2009070143 W JP2009070143 W JP 2009070143W WO 2010067728 A1 WO2010067728 A1 WO 2010067728A1
- Authority
- WO
- WIPO (PCT)
- Prior art keywords
- piston
- layer
- gas lubrication
- lubrication structure
- expansion
- Prior art date
Links
Images
Classifications
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
- F02G—HOT GAS OR COMBUSTION-PRODUCT POSITIVE-DISPLACEMENT ENGINE PLANTS; USE OF WASTE HEAT OF COMBUSTION ENGINES; NOT OTHERWISE PROVIDED FOR
- F02G1/00—Hot gas positive-displacement engine plants
- F02G1/04—Hot gas positive-displacement engine plants of closed-cycle type
- F02G1/043—Hot gas positive-displacement engine plants of closed-cycle type the engine being operated by expansion and contraction of a mass of working gas which is heated and cooled in one of a plurality of constantly communicating expansible chambers, e.g. Stirling cycle type engines
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
- F02G—HOT GAS OR COMBUSTION-PRODUCT POSITIVE-DISPLACEMENT ENGINE PLANTS; USE OF WASTE HEAT OF COMBUSTION ENGINES; NOT OTHERWISE PROVIDED FOR
- F02G2270/00—Constructional features
- F02G2270/40—Piston assemblies
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F05—INDEXING SCHEMES RELATING TO ENGINES OR PUMPS IN VARIOUS SUBCLASSES OF CLASSES F01-F04
- F05C—INDEXING SCHEME RELATING TO MATERIALS, MATERIAL PROPERTIES OR MATERIAL CHARACTERISTICS FOR MACHINES, ENGINES OR PUMPS OTHER THAN NON-POSITIVE-DISPLACEMENT MACHINES OR ENGINES
- F05C2251/00—Material properties
- F05C2251/04—Thermal properties
- F05C2251/042—Expansivity
- F05C2251/046—Expansivity dissimilar
Definitions
- the present invention relates to a piston gas lubrication structure and a Stirling engine, and more particularly, to a piston gas lubrication structure including a piston that performs gas lubrication with a cylinder, and a Stirling engine including the piston gas lubrication structure.
- Patent Documents 3 to 6 techniques for providing a resin on the piston are disclosed in, for example, Patent Documents 3 to 6.
- resin is provided for the purpose of reducing friction between the cylinder and the piston in sliding contact.
- the technique disclosed in Patent Document 6 provides a resin for the purpose of functioning as a cushioning material.
- Japanese Patent Laid-Open No. 2006-183666 Japanese Patent Laid-Open No. 2005-106010 Japanese Patent Laid-Open No. 61-135967 JP 2006-161563 A JP-A-5-1620 JP-A-6-93927
- foreign matter when performing gas lubrication with the cylinder, foreign matter may enter the clearance between the cylinder and the piston, and the foreign matter that has entered may grow.
- foreign matters such as metal pieces remaining in the heat exchanger may enter the clearance during engine operation and grow.
- the surface pressure increases due to the sliding of the piston through the foreign matter, causing foreign matter to adhere, which may result in performance degradation. It was.
- the foreign matter may be removed in advance, for example.
- the present invention has been made in view of the above problems, and when gas lubrication is performed, foreign matter enters the clearance formed between the cylinder and adhesion even if the foreign matter grows. It is an object of the present invention to provide a piston gas lubrication structure capable of suppressing the occurrence of the above-described phenomenon and thereby greatly enhancing the resistance to foreign matters, and a Stirling engine equipped with the piston gas lubrication structure.
- the present invention for solving the above problems is provided on a cylinder, a piston in which gas lubrication is performed between the cylinder, and an outer peripheral surface of the piston, and has a higher linear expansion coefficient than a base material of the piston, And a gas lubrication structure of a piston comprising a layer formed of a flexible material.
- the present invention preferably has a configuration in which the thickness of the layer at room temperature is equal to or larger than the clearance formed between the layer and the cylinder.
- the present invention preferably has a configuration in which the thickness of the layer at room temperature is such that a clearance can be formed between the layer and the cylinder even if thermal expansion occurs under use conditions.
- the piston is provided with a stepped portion in which the layer is provided and a diameter-enlarged portion where gas lubrication is performed between the piston and a diameter-reduced portion provided on the diameter-enlarged portion.
- a configuration that is a piston is preferred.
- At least the diameter-enlarged portion of the piston has a thin thickness.
- the piston has a combination of two truncated cones and includes a drum-shaped reinforcing member that connects an upper portion and a lower portion of the piston.
- the present invention is a Stirling engine comprising the piston gas lubrication structure according to any one of claims 1 to 6 and an approximate linear mechanism connected to the piston and supporting the piston.
- the piston is preferably a high temperature side piston.
- the present invention it is possible to suppress the occurrence of adhesion even if foreign matter enters the clearance formed between the cylinders when performing gas lubrication, and the foreign matter that has grown grows. Therefore, the resistance to foreign matters can be greatly increased.
- FIG. 1 is a diagram schematically illustrating a Stirling engine 10A.
- FIG. 2 is a diagram schematically showing a schematic configuration of the piston / crank portion.
- FIG. 3 is a diagram schematically showing an enlarged portion around the radial clearance.
- FIG. 4 is a diagram schematically showing a change in the thickness of the layer 60 due to thermal expansion.
- FIG. 5 is a diagram showing the metal part radius clearance H ′ after thermal expansion for each different linear expansion coefficient difference ⁇ according to the temperature difference ⁇ T before and after thermal expansion.
- FIG. 6 is a diagram schematically showing the gas lubrication structure 1C in cross section.
- FIG. 7 is a diagram schematically showing the gas lubrication structure 1D in cross section.
- FIG. 8 is a diagram schematically showing the gas lubrication structure 1E in cross section.
- FIG. 1 is a view schematically showing a Stirling engine 10A having a piston gas lubrication structure (hereinafter simply referred to as a gas lubrication structure) 1A.
- the Stirling engine 10A is an ⁇ -type (two-piston type) Stirling engine, and includes a high temperature side cylinder 20A and a low temperature side cylinder 30 arranged in series.
- the high temperature side cylinder 20A includes an expansion piston 21A and a high temperature side cylinder 22, and the low temperature side cylinder 30 includes a compression piston 31 and a low temperature side cylinder 32, respectively.
- the compression piston 31 is provided with a phase difference so as to move with a delay of about 90 ° in crank angle with respect to the expansion piston 21A.
- the upper space of the high temperature side cylinder 22 is an expansion space.
- the working fluid heated by the heater 47 flows into the expansion space.
- the heater 47 is specifically disposed inside an exhaust pipe 100 of a gasoline engine mounted on a vehicle, and the working fluid is heated by thermal energy recovered from the exhaust gas.
- the upper space of the low temperature side cylinder 32 is a compression space.
- the working fluid cooled by the cooler 45 flows into the compression space.
- the regenerator 46 exchanges heat with the working fluid reciprocating between the expansion space and the compression space. Specifically, the regenerator 46 receives heat from the working fluid when the working fluid flows from the expansion space to the compression space, and releases the stored heat to the working fluid when the working fluid flows from the compression space to the expansion space. .
- Air is applied to the working fluid.
- the present invention is not limited to this, and a gas such as He, H 2 , or N 2 can be applied to the working fluid.
- the operation of the Stirling engine 10A will be described.
- the working fluid is heated by the heater 47, it expands and the expansion piston 21A is pressed down, whereby the drive shaft 111 is rotated.
- the expansion piston 21 ⁇ / b> A moves to the ascending stroke, the working fluid passes through the heater 47 and is transferred to the regenerator 46 where heat is released and flows to the cooler 45.
- the working fluid cooled by the cooler 45 flows into the compression space, and is further compressed as the compression piston 31 moves upward.
- the working fluid thus compressed rises in temperature while taking heat from the regenerator 46 and flows into the heater 47 where it is heated and expanded again. That is, the Stirling engine 10A operates through the reciprocating flow of the working fluid.
- the heat source of the Stirling engine 10A is the exhaust gas of the internal combustion engine of the vehicle, there is a restriction on the amount of heat obtained, and it is necessary to operate the Stirling engine 10A within the range of the obtained heat amount. . Therefore, in this embodiment, the internal friction of the Stirling engine 10A is reduced as much as possible. Specifically, gas lubrication is performed between the cylinders 22 and 32 and the pistons 21A and 31 in order to eliminate the friction loss due to the piston ring having the largest friction loss among the internal friction of the Stirling engine 10A.
- the pressure (distribution) of air generated by a minute clearance between the cylinders 22 and 32 and the pistons 21A and 31 is used to make the pistons 21A and 31 float in the air. Since the gas lubrication has an extremely small sliding resistance, the internal friction of the Stirling engine 10A can be greatly reduced.
- the static pressure gas lubrication is performed in the present embodiment.
- the static pressure gas lubrication is a method in which a pressurized fluid is ejected and an object (the pistons 21A and 31 in this embodiment) is levitated by the generated static pressure.
- the pressurized fluid is a working fluid in the present embodiment, and the working fluid is introduced into the expansion piston 21A and a plurality of air supply holes (illustrated) penetrating from the inside of the expansion piston 21A to the outer peripheral surface. (Omitted).
- the gas lubrication is not limited to static pressure gas lubrication, and may be dynamic pressure gas lubrication, for example.
- the clearance between the cylinders 22 and 32 and the pistons 21A and 31 where gas lubrication is performed is several tens of ⁇ m. Then, the working fluid of the Stirling engine 10A is interposed in this clearance.
- Each of the pistons 21A and 31 is supported in a non-contact state or an allowable contact state with the cylinders 22 and 32 by gas lubrication. Therefore, the piston ring is not provided around the pistons 21A and 31, and the lubricating oil generally used with the piston ring is not used.
- gas lubrication the airtightness of each of the expansion space and the compression space is maintained by minute clearance, and clearance sealing is performed without a ring and without an oil.
- pistons 21A, 31 and the cylinders 22, 32 are both made of metal, and specifically in the present embodiment, the corresponding pistons 21A, 31 and the cylinders 22, 32 have the same linear expansion coefficient (here, SUS). Has been applied. Thereby, even if there is thermal expansion, it is possible to perform gas lubrication while maintaining an appropriate clearance.
- SUS linear expansion coefficient
- the side force of the pistons 21A and 31 must be made substantially zero. That is, when performing gas lubrication, the ability to withstand the force in the diametrical direction (lateral direction, thrust direction) (pressure resistance ability) of the cylinders 22 and 32 is low. The motion accuracy needs to be high.
- a grasshopper mechanism 50 is employed as an approximate linear mechanism in the piston / crank portion.
- the approximate linear mechanism includes, for example, a watt mechanism in addition to the grasshopper mechanism 50, but the size of the mechanism required for obtaining the same linear motion accuracy is smaller than that of the other approximate linear mechanisms.
- the entire apparatus can be made compact.
- the Stirling engine 10A of this embodiment is installed in a limited space such as under the floor of an automobile, the degree of freedom of installation increases when the entire apparatus is compact.
- the grasshopper mechanism 50 is advantageous in terms of fuel consumption because the weight of the mechanism required to obtain the same linear motion accuracy is lighter than that of the other mechanisms. Further, the grasshopper mechanism 50 has an advantage that the structure (manufacturing and assembly) is easy because the structure of the mechanism is relatively simple.
- FIG. 2 is a diagram schematically showing a schematic configuration of a piston / crank portion of the Stirling engine 10A. Since the piston / crank portion employs a common configuration for the high temperature side cylinder 20A side and the low temperature side cylinder 30 side, only the high temperature side cylinder 20A side will be described below, and the low temperature side cylinder 30 side will be described. Description of is omitted.
- the reciprocating motion of the expansion piston 21A is transmitted to the drive shaft 111 by the connecting rod 110, where it is converted into a rotational motion.
- the connecting rod 110 is supported by a grasshopper mechanism 50, and reciprocates the expansion piston 21A linearly. Since the connecting rod 110 is supported by the grasshopper mechanism 50 in this way, the side force F of the expansion piston 21A becomes almost zero, so that the expansion piston 21A is sufficiently supported even when performing gas lubrication with a small load capacity. be able to.
- a layer 60 is provided on the outer peripheral surface of the expansion piston 21A (for example, the surface facing the wall surface of the high temperature side cylinder 22).
- the gas lubrication structure 1 ⁇ / b> A is realized by the expansion piston 21 ⁇ / b> A, the high temperature side cylinder 22, and the layer 60.
- the layer 60 according to the present invention is desirably provided on all outer peripheral surfaces of the expansion piston 21A, but may be provided on any portion of the outer peripheral surface of the expansion piston 21A. Further, the layer 60 according to the present invention may be provided on any part of the wall surface of the high temperature side cylinder 22.
- FIG. 3 is a diagram schematically showing an enlarged peripheral portion of a clearance (hereinafter also referred to as a radial clearance) formed with the high temperature side cylinder 22.
- a clearance hereinafter also referred to as a radial clearance
- FIG. 3 shows a state before thermal expansion (state at room temperature T 0 ) in FIG. 3 (a), and a state after thermal expansion (at maximum use temperature T 1 ) in FIG. 3 (b).
- h is the radial clearance
- H is the metal part radial clearance
- t is the thickness of the layer 60
- D is the inner diameter of the high temperature side cylinder 22
- d is the outer diameter of the base material of the expansion piston 21A
- ⁇ c is the high temperature side cylinder 22.
- the linear expansion coefficient of the material ⁇ p represents the linear expansion coefficient of the material of the expansion piston 21A
- ⁇ r represents the linear expansion coefficient of the material of the layer 60.
- “′” indicates that after thermal expansion.
- the normal temperature T 0 is, for example, ⁇ 40 ° C.
- the maximum use temperature T 1 is, for example, 400 ° C.
- the layer 60 is provided by coating a resin.
- the resin has a higher linear expansion coefficient than the base material of the metal expansion piston 21A ( ⁇ r> ⁇ p) and is a flexible material.
- the resin is specifically a fluorine resin. Since the resin generally has a linear expansion coefficient that is about 4 to 10 times higher than that of metal, it may be difficult to apply the resin to the outer peripheral surface of the expansion piston 21A having a radial clearance of about several tens of ⁇ m.
- the linear expansion coefficient of the layer 60 is a linear expansion coefficient that can reduce the clearance formed between the high temperature side cylinder 22 and the temperature.
- the thickness of the layer 60 under the normal temperature T 0 is equal to or greater than the radial clearance (t ⁇ h). Specifically, in this embodiment, the thickness t of the layer 60 is 50 ⁇ m, and the radial clearance size h is 20 ⁇ m. That is, in this embodiment, the thickness of the layer 60 is more than twice the size of the radial clearance.
- the thickness of the layer 60 is realized by coating the resin overlying a plurality of times.
- the thickness of the layer 60 under the normal temperature T 0 is a thickness capable of maintaining the clearance formed between the high-temperature side cylinder 22 even if thermal expansion occurs under use conditions. Specifically, the thickness t of the layer 60 is set within a range represented by the following formula 1.
- ⁇ is a Poisson's ratio
- ⁇ T is a temperature difference between the normal temperature T 0 and the maximum use temperature T 1 .
- a metal here, SUS
- the metal portion radial clearance does not substantially change before and after the thermal expansion (H ⁇ H ′), while the thickness of the layer 60 having a higher linear expansion coefficient than that of the metal increases after the thermal expansion (t ⁇ t ′),
- the radial clearance becomes smaller after thermal expansion (h> h ′).
- the size of foreign matter that can enter the radial clearance is basically limited to foreign matters smaller than the radial clearance h at room temperature T 0, and it is assumed that the layer 60 is in contact with the high temperature side cylinder 22 exceptionally.
- the maximum is about twice the size of the radial clearance (2h).
- the intrusion and growth of the foreign substances can be allowed until the foreign substances have a size (h + t) obtained by adding the radial clearance h and the thickness t of the layer 60.
- the layer 60 is formed of a fluorine-based resin that is a material having a solid lubricating function, adhesion due to the layer 60 itself can be prevented.
- the gas lubrication structure 1A and the Stirling engine 10A can suppress the occurrence of adhesion even when foreign matter enters the radial clearance and grows, thereby greatly increasing the resistance to the foreign matter. Can do.
- Equation 1 gas lubrication is performed in order to significantly reduce internal friction by avoiding sliding friction. For this reason, a fluorine-based resin having a solid lubricating function is not selected for the purpose of reducing sliding friction.
- FIG. 4 is a diagram schematically showing a change in the thickness of the layer 60 due to thermal expansion.
- the circumferential extension and the height extension of the layer 60 are suppressed by the base material of the expansion piston 21A. And it is thought that the total thermal expansion volume of the suppressed part is converted into the thickness direction.
- ⁇ t ′ the amount of change ⁇ t ′ in thickness when it is assumed that the entire volume of the restricted elongation is replaced in the thickness direction is expressed by the following Equation 4.
- Equation 1 can be derived.
- the Stirling engine 10B is substantially the same as the Stirling engine 10A except that the gas lubrication structure 1B is provided instead of the gas lubrication structure 1A.
- the gas lubrication structure 1B is substantially the same as the gas lubrication structure 1A except that the expansion piston 21B is provided instead of the expansion piston 21A.
- the expansion piston 21B is substantially the same as the expansion piston 21A except that the material is different from that of the high temperature side cylinder 22. For this reason, in this embodiment, the gas lubrication structure 1B and the Stirling engine 10B are not shown.
- a material in which the difference in linear expansion coefficient between the expansion piston 21B and the high temperature side cylinder 22 falls within the range of difference in which a radial clearance can be formed even if there is thermal expansion occurring under the use conditions. can do.
- a material in which the linear expansion coefficient difference ⁇ between the expansion piston 21B and the high temperature side cylinder 22 is 5 ⁇ 10 ⁇ 6 [1 / k] or less can be applied to the material of the expansion piston 21B.
- FIG. 5 is a diagram showing the metal part radial clearance H ′ after thermal expansion for each different linear expansion coefficient difference ⁇ according to the temperature difference ⁇ T before and after thermal expansion.
- the tolerances of the expansion piston 21B and the high temperature side cylinder 22 are 0.005 mm or less respectively, and the metal part radius required for gas lubrication at room temperature
- the clearance H was set to d / 1000 mm or less (H ⁇ d / 1000), and the metal part radius clearance H ′ required after thermal expansion was set to 0.01 mm (H ′ ⁇ 0.01).
- the region between the initial metal part radius clearance of 0.04 mm and the metal part radius clearance of 0.01 mm necessary after thermal expansion is the high temperature side use range based on the above conditions.
- the linear expansion coefficient difference ⁇ is reduced from 25 ⁇ 10 ⁇ 6 mm, a larger temperature difference ⁇ T can be secured.
- the metal part radial clearance after thermal expansion becomes 0 mm when the temperature difference ⁇ T is 100 ° C. Is limited when the temperature difference ⁇ T is about 75 ° C.
- the working fluid having a high temperature of about 400 ° C. contacts the top surface of the expansion piston 21B, and at least the temperature difference ⁇ T exceeds 75 ° C. Therefore, when the linear expansion coefficient difference ⁇ is 10 ⁇ 10 ⁇ 6 It becomes inappropriate.
- the metal part radial clearance is not 0 mm until the temperature difference ⁇ T reaches 200 ° C., and is used until the temperature difference ⁇ T reaches 150 ° C. I understand that I can do it.
- the maximum use temperature in the vicinity of the radial clearance of the metal part needs to be suppressed to a temperature that also takes into consideration the heat resistant temperature of the layer 60 (for example, 260 ° C.). If the temperature difference ⁇ T is 150 ° C., the temperature of the layer 60 is reduced. It can be suppressed below the heat-resistant temperature.
- the linear expansion coefficient difference ⁇ T is preferably 5 ⁇ 10 ⁇ 6 [1 / k] or less.
- the gas lubrication structure 1B and the Stirling engine 10B including the expansion piston 21B and the high temperature side cylinder 22 having different materials the gas lubrication structure can be used even when the materials of the expansion piston 21B and the high temperature side cylinder 22 are different.
- the same effect as 1A and Stirling engine 10 can be obtained.
- the case of the Stirling engine 10B provided with the expansion piston 21B and the high temperature side cylinder 22 has been described in detail. However, appropriate materials may be applied to the piston and the cylinder according to the present invention.
- the Stirling engine 10C according to the present embodiment is substantially the same as the Stirling engine 10A except that the gas lubrication structure 1C is provided instead of the gas lubrication structure 1A.
- the gas lubrication structure 1C is substantially the same as the gas lubrication structure 1A except that the expansion piston 21C is provided instead of the expansion piston 21A.
- FIG. 6 is a diagram schematically showing the gas lubrication structure 1C in cross section together with a graph of the temperature distribution of the expansion piston 21C.
- the expansion piston 21 ⁇ / b> C includes a temperature reduction region where the layer 60 is not provided on the outer peripheral surface.
- the temperature reduction region is more specifically a reduced diameter portion 21aC in which the diameter is smaller than the diameter of the lower portion of the outer peripheral surface (specifically, the skirt portion here).
- the expansion piston 21C is a stepped piston.
- the layer 60 is provided in the enlarged diameter portion 21bC corresponding to the skirt portion of the expansion piston 21C.
- the layer 60 can be provided on the high temperature side cylinder 22, but it is necessary to provide the layer 60 over the entire movable range of the expansion piston 21C in order to suppress the occurrence of adhesion. In this case, however, contact between the layer 60 and the hot working fluid cannot be avoided. For this reason, in this embodiment, the layer 60 is provided in the enlarged diameter portion 21bC of the expansion piston 21C. In the expansion piston 21C, gas lubrication is performed between the expanded diameter portion 21bC and the high temperature side cylinder 22.
- the expansion piston 21C In the expansion piston 21C, the enlarged diameter portion 21bC is made thin. Further, in the expansion piston 21C, the head portion is hollowed into a bottomed cylindrical shape leaving the top surface, and the thickness of the temperature reduction region (the reduced diameter portion 21aC) is reduced. The thinning is preferably as thin as possible. In this embodiment, the thinning is performed to such an extent that the expansion piston 21C requires reinforcement. Accordingly, in response to this, the expansion piston 21C has a combination of two truncated cones, and further includes a drum-shaped reinforcing member 70 that connects the upper portion and the lower portion of the expansion piston 21C. The reinforcing member 70 has an upper portion integrated with the expansion piston 21C and a lower portion provided by welding.
- the thickness of the reinforcing member 70 is thin.
- the shapes of the temperature reduction region (the reduced diameter portion 21aC), the enlarged diameter portion 21bC, and the reinforcing member 70 are substantially symmetrical with respect to the central axis of the expansion piston 21C.
- the heat transfer Q1 from the top surface of the expansion piston 21C to the enlarged diameter portion 21bC can be reduced by providing the temperature reduction region.
- the temperature reduction region is the reduced diameter portion 21aC
- thermal expansion of the reduced diameter portion 21aC where the metal is exposed can be allowed. That is, it is possible to prevent foreign matter from adhering to the reduced diameter portion 21aC where the metal is exposed.
- the length in the direction along the axis of the temperature reduction region can be shortened, and the size of the temperature reduction region can be reduced.
- the heat transfer Q1 can be reduced by reducing the thickness of the temperature reduction region (the reduced diameter portion 21aC) and the enlarged diameter portion 21bC.
- the length in the direction along the axis of the temperature reduction region can be shortened, and the size of the temperature reduction region can be reduced.
- the reinforcing member 70 is provided, rigidity can be ensured against the reduction in the thickness of the temperature reduction region (the reduced diameter portion 21aC) and the enlarged diameter portion 21bC. Further, by reducing the thickness of the reinforcing member 70, the heat transfer Q2 from the top surface of the expansion piston 21C through the reinforcing member 70 to the enlarged diameter portion 21bC can be reduced.
- the piston temperature of the part (here enlarged diameter part 21bC) which provided the layer 60 can be suppressed below to heat-resistant temperature (here 260 degreeC).
- the expansion piston 21C can be made lightweight and compact by these.
- the shape of the temperature reduction region (the reduced diameter portion 21aC), the enlarged diameter portion 21bC, and the reinforcing member 70 is made substantially symmetrical with respect to the central axis of the expansion piston 21C, so that the thermal deformation of the expansion piston 21C is prevented. It can be made uniform. Thereby, it is possible to prevent the adverse effect due to thermal deformation from affecting gas lubrication.
- the gas lubrication structure 1C and the Stirling engine 10C can suppress the piston temperature of the portion where the layer 60 is further provided to the heat resistant temperature or less as compared with the gas lubrication structure 1A and the Stirling engine 10A.
- Example 3 the head portion is hollowed into a bottomed cylindrical shape leaving the top surface of the expansion piston 21C, and the reduced diameter portion 21aC is provided.
- the reduced diameter portion 21aD provided without making the head portion particularly hollow can also be realized.
- the thinning may be performed only on the thickness of the enlarged diameter portion 21bE as in the gas lubrication structure 1E shown in FIG.
- the layer 60 is provided on the expansion piston 21 .
- the layer is provided on the compression piston which is a low temperature side piston. May be.
- the gas lubrication structure of the present invention is suitable for a Stirling engine, but its application is not necessarily limited to a Stirling engine, and the Stirling engine of the present invention is limited to a type that is attached to an exhaust pipe of an internal combustion engine of a vehicle. I can't.
Landscapes
- Engineering & Computer Science (AREA)
- Chemical & Material Sciences (AREA)
- Combustion & Propulsion (AREA)
- Mechanical Engineering (AREA)
- General Engineering & Computer Science (AREA)
- Pistons, Piston Rings, And Cylinders (AREA)
Abstract
Description
なお、異物の侵入を防止するためには、例えば異物を予め除去すればよいとも考えられる。しかしながら、例えばスターリングエンジンの場合、気体潤滑が行われる数十μm程度のシリンダ、ピストン間のクリアランスに侵入する微小な異物を熱交換器から予め完全に除去するのは困難という事情がある。また、仮に異物を除去できたとしても、例えば金網を内蔵する熱交換器からは機関運転中に微小な金属片が剥がれ落ちることがあるために、これには対処できないという事情もある。
低温側シリンダ32の上部空間は圧縮空間となっている。圧縮空間には冷却器45で冷却された作動流体が流入する。
再生器46は、膨張空間、圧縮空間の間を往復する作動流体との間で熱の授受を行う。再生器46は具体的には、作動流体が膨張空間から圧縮空間へと流れる時には作動流体から熱を受け取り、作動流体が圧縮空間から膨張空間へと流れる時には蓄えられた熱を作動流体に放出する。
作動流体には空気が適用されている。但しこれに限られず、作動流体には例えばHe、H2、N2等の気体を適用することができる。
さらに常温T0下の層60の厚さは、使用条件下で発生する熱膨張があっても、高温側シリンダ22との間に形成されるクリアランスを維持可能な厚さとなっている。具体的には層60の厚さtは、次の式1で示される範囲内で設定されている。
t≦h/{(1+4ν)(αr-αc)ΔT}・・・(式1)
ここで、νはポアソン比、ΔTは常温T0と最高使用温度T1との温度差である。
一方、半径クリアランスに侵入可能な異物の大きさは、基本的に常温T0時の半径クリアランスhより小さな異物に限られ、例外的に層60が高温側シリンダ22に接触した状態を想定して最大で半径クリアランスの大きさの2倍(2h)程度となる。
また、侵入した異物同士が結合して成長する場合でも、異物が半径クリアランスhと層60の厚さtとを足した大きさ(h+t)になるまで、異物の侵入、成長を許容できる。
また、層60は固体潤滑機能を持つ材料であるフッ素系の樹脂で形成されているため、層60そのものに起因して凝着が発生することも防止される。
このように気体潤滑構造1Aおよびスターリングエンジン10Aは、半径クリアランスに異物が侵入し、また成長した場合であっても凝着が発生することを抑制でき、以って異物に対する耐性を大幅に高めることができる。
また、以下、式1の導出方法について詳述する。
t´´=(1+αr×ΔT)×t・・・・(式2)
しかし、実際には周方向と高さ方向の伸びが、膨張ピストン21Aの母材の伸びに制約される。膨張ピストン21Aの母材の伸びtpは次の式3で示される。
tp=(1+αc×ΔT)×t・・・・(式3)
但しαc=αpである。
Δt´={(t´´2-tp2)/tp2}×t´´
=[{(1+αr×ΔT)2-(1+αc×ΔT)2}
/(1+αc×ΔT)2]×t´´・・・・(式4)
t´=t´´+Δt´・・・・(式5)
式5に式2と式4を代入すると式6になる。
t´={(1+αr×ΔT)2/(1+αc×ΔT)2}×t´´
={(1+αr×ΔT)3/(1+αc×ΔT)2}×t・・・・(式6)
ここで、熱膨張後の半径クリアランスh´をゼロ以上とすると、熱膨張後の金属部半径クリアランスH´と厚さt´との関係は次の式7で示される。
H´≧t´・・・・(式7)
また熱膨張後の金属部半径クリアランスH´は次の式8で示される。
H´=(1+αc×ΔT)×H・・・・(式8)
H/t≧(1+αr×ΔT)3/(1+αc×ΔT)3
=[1+(αr-αc)×ΔT/(1+αc×ΔT)]3
≒1+3(αr-αc)×ΔT/(1+αc×ΔT)・・・(式9)
また金属部半径クリアランスHは次の式10で示される。
H=h+t・・・・(式10)
式10を用いて式9を整理すると、次の式11になる。
t≦(1+αc×ΔT)×h/{3(αr-αc)×ΔT}
=h/{3(αr-αc)×ΔT}・・・・(式11)
ここで、式11はポアソン比ν=0.5の場合(例えば水)のものである。このため、固体の場合として式11にポアソン比νを入れると式1を導出できる。
t≦h/{(1+4ν)(αr-αc)ΔT}・・・・(式1)
なお、本実施例では膨張ピストン21Bと高温側シリンダ22とを備えたスターリングエンジン10Bの場合について詳述したが、本発明に係るピストンとシリンダには適宜の素材が適用されてよい。
このためこれに応じて、膨張ピストン21Cは2つの円錐台形の組み合わせを有し、膨張ピストン21Cの上部と下部とを接続する鼓状の補強部材70を内部にさらに備えている。補強部材70は、上の部分が膨張ピストン21Cと一体となっており、下の部分は溶接によって設けられている。補強部材70の肉厚は薄肉となっている。温度低減領域(縮径部21aC)、拡径部21bCおよび補強部材70の形状は膨張ピストン21Cの中心軸線で略対称な形状となっている。
また温度低減領域を縮径部21aCとしたことで、金属が露出した縮径部21aCの熱膨張を許容することができる。すなわち、これにより金属が露出した縮径部21aCで異物の凝着が発生することを防止できる。またこれにより、温度低減領域の軸線に沿った方向の長さを短くし、温度低減領域のサイズを小さくすることができる。
また温度低減領域(縮径部21aC)と拡径部21bCの肉厚を薄肉にしたことで、伝熱Q1を低減することができる。またこれにより、温度低減領域の軸線に沿った方向の長さを短くし、温度低減領域のサイズを小さくすることができる。
また補強部材70を備えたことにより、温度低減領域(縮径部21aC)、拡径部21bCの肉厚を薄肉にしたことに対して剛性を確保することができる。
さらに補強部材70の肉厚を薄肉にしたことで、補強部材70を通じた膨張ピストン21Cの頂面から拡径部21bCへの伝熱Q2を低減することができる。
さらにスターリングエンジン10Cでは、温度低減領域(縮径部21aC)、拡径部21bCおよび補強部材70の形状を膨張ピストン21Cの中心軸線で略対称な形状としたことで、膨張ピストン21Cの熱変形を均一にすることができる。これにより、熱変形による悪影響が気体潤滑に及ぶことも防止できる。
このように気体潤滑構造1Cおよびスターリングエンジン10Cは、気体潤滑構造1Aおよびスターリングエンジン10Aと比較してさらに層60を設けた部分のピストン温度を耐熱温度以下に抑制することなどができる。
例えば実施例3では、膨張ピストン21Cの頂面を残す形でヘッド部を有底円筒状に中空にした上で縮径部21aCを設けたが、例えば図7に示す気体潤滑構造1Dのようにヘッド部を特段中空にすることなく設けられた縮径部21aDも実現可能である。また薄肉化は例えば図8に示す気体潤滑構造1Eのように拡径部21bEの肉厚に対してのみ行われてもよい。
また本発明の気体潤滑構造はスターリングエンジンに好適であるが、必ずしもその適用がスターリングエンジンに限られるものではなく、本発明のスターリングエンジンは車両の内燃機関の排気管に取り付けられる形式のものに限られない。
10 スターリングエンジン
20 高温側気筒
21 膨張ピストン
22 高温側シリンダ
30 低温側気筒
45 冷却器
46 再生器
47 加熱器
50 グラスホッパの機構
60 層
70 補強部材
100 排気管
110 コネクティングロッド
111 駆動軸
Claims (8)
- シリンダと、
前記シリンダとの間で気体潤滑が行われるピストンと、
前記ピストンの外周面に設けられ、前記ピストンの母材よりも線膨張率が高く、且つ柔軟性のある材料で形成される層と、
を備えるピストンの気体潤滑構造。 - 常温下の前記層の厚さは、前記層と前記シリンダとの間に形成されるクリアランスの大きさ以上であることを特徴とする請求項1記載のピストンの気体潤滑構造。
- 常温下の前記層の厚さは、使用条件下で発生する熱膨張があっても、前記層と前記シリンダとの間にクリアランスを形成可能な厚さであることを特徴とする請求項1または2記載のピストンの気体潤滑構造。
- 前記ピストンは、前記層が設けられるとともに、前記シリンダとの間で気体潤滑が行われる拡径部と、前記拡径部の上に設けられる縮径部とを備えた段付きピストンであることを特徴とする請求項1から3のいずれか1項記載のピストンの気体潤滑構造。
- 前記ピストンの肉厚のうち、少なくとも前記拡径部の肉厚が薄肉であることを特徴とする請求項4記載のピストンの気体潤滑構造。
- 前記ピストンは、2つの円錐台形の組み合わせを有し、前記ピストンの上部と下部とを接続する鼓状の補強部材を内部に備えることを特徴とする請求項4または5記載のピストンの気体潤滑構造。
- 請求項1から6いずれか1項記載のピストンの気体潤滑構造と、
前記ピストンに連結されて前記ピストンを支持する近似直線機構と、
を備えるスターリングエンジン。 - 前記ピストンが高温側ピストンである請求項7記載のスターリングエンジン。
Priority Applications (4)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
CN200980149954.6A CN102245888B (zh) | 2008-12-10 | 2009-12-01 | 活塞的气体润滑结构及斯特林发动机 |
US13/124,008 US8763514B2 (en) | 2008-12-10 | 2009-12-01 | Gas lubrication structure for piston, and stirling engine |
JP2010542081A JP5110173B2 (ja) | 2008-12-10 | 2009-12-01 | ピストンの気体潤滑構造およびスターリングエンジン |
EP09831832.2A EP2357348B1 (en) | 2008-12-10 | 2009-12-01 | Gas lubrication structure for piston, and stirling engine |
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP2008-313949 | 2008-12-10 | ||
JP2008313949 | 2008-12-10 |
Publications (1)
Publication Number | Publication Date |
---|---|
WO2010067728A1 true WO2010067728A1 (ja) | 2010-06-17 |
Family
ID=42242717
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
PCT/JP2009/070143 WO2010067728A1 (ja) | 2008-12-10 | 2009-12-01 | ピストンの気体潤滑構造およびスターリングエンジン |
Country Status (5)
Country | Link |
---|---|
US (1) | US8763514B2 (ja) |
EP (1) | EP2357348B1 (ja) |
JP (1) | JP5110173B2 (ja) |
CN (1) | CN102245888B (ja) |
WO (1) | WO2010067728A1 (ja) |
Cited By (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JP2012172672A (ja) * | 2011-02-24 | 2012-09-10 | Toyota Motor Corp | スターリングエンジンの気体導入構造 |
JP5528647B1 (ja) * | 2014-02-21 | 2014-06-25 | 信也 ▲高▼原 | ピストン型内燃機関 |
Families Citing this family (10)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JP5418358B2 (ja) * | 2010-03-26 | 2014-02-19 | トヨタ自動車株式会社 | スターリングエンジン |
US9004038B2 (en) | 2011-12-29 | 2015-04-14 | Etagen, Inc. | Methods and systems for managing a clearance gap in a piston engine |
WO2013101786A1 (en) * | 2011-12-29 | 2013-07-04 | Etagen, Inc. | Methods and systems for managing a clearance gap in a piston engine |
US20130167797A1 (en) | 2011-12-29 | 2013-07-04 | Matt Svrcek | Methods and systems for managing a clearance gap in a piston engine |
US9097203B2 (en) | 2011-12-29 | 2015-08-04 | Etagen, Inc. | Methods and systems for managing a clearance gap in a piston engine |
US9169797B2 (en) | 2011-12-29 | 2015-10-27 | Etagen, Inc. | Methods and systems for managing a clearance gap in a piston engine |
US8720317B2 (en) | 2011-12-29 | 2014-05-13 | Etagen, Inc. | Methods and systems for managing a clearance gap in a piston engine |
US10215229B2 (en) | 2013-03-14 | 2019-02-26 | Etagen, Inc. | Mechanism for maintaining a clearance gap |
CN108375538B (zh) * | 2018-02-06 | 2020-04-28 | 湘潭大学 | 一种用于材料火花鉴别的打磨装置 |
CA3107650A1 (en) | 2018-07-24 | 2020-01-30 | Mainspring Energy, Inc. | Linear electromagnetic machine |
Citations (8)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US3777722A (en) * | 1969-09-11 | 1973-12-11 | K Lenger | Free piston engine |
JPS61135967A (ja) | 1984-12-04 | 1986-06-23 | Kawasaki Heavy Ind Ltd | 無給油型2サイクルエンジン |
JPH051620A (ja) | 1991-06-26 | 1993-01-08 | Atsugi Unisia Corp | ピストン |
JPH0693927A (ja) | 1992-07-27 | 1994-04-05 | Isuzu Motors Ltd | 内燃機関のピストン |
JP2005106009A (ja) | 2003-10-01 | 2005-04-21 | Toyota Motor Corp | スターリングエンジン及びそれを備えたハイブリッドシステム |
JP2005520095A (ja) * | 2001-12-18 | 2005-07-07 | デルフィ テクノロジーズ,インコーポレイティド | 対向ピストン式内燃機関 |
JP2006161563A (ja) | 2004-12-02 | 2006-06-22 | Honda Motor Co Ltd | 内燃機関のピストン |
JP2006183566A (ja) | 2004-12-27 | 2006-07-13 | Toyota Motor Corp | ピストン装置、スターリングエンジン、及び外燃機関 |
Family Cites Families (8)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US377722A (en) * | 1888-02-07 | Die for cutting and pointing wire nails | ||
US3127955A (en) * | 1956-03-30 | 1964-04-07 | Macks Elmer Fred | Fluid supported device |
US4330993A (en) * | 1979-11-26 | 1982-05-25 | Sunpower, Inc. | Hydrodynamic lubrication system for piston devices particularly Stirling engines |
US4831977A (en) * | 1987-07-17 | 1989-05-23 | Ethyl Corporation | Pistons with wear resistant solid film lubricant coatings |
US4846051A (en) * | 1988-02-23 | 1989-07-11 | Ford Motor Company | Uncooled oilless internal combustion engine having uniform gas squeeze film lubrication |
CN100404837C (zh) * | 2003-09-25 | 2008-07-23 | 珍巴多工业股份有限公司 | 斯特林循环发动机 |
WO2005033592A2 (ja) | 2003-10-01 | 2005-04-14 | Toyota Jidosha Kabushiki Kaisha | スターリングエンジン及びそれを備えたハイブリッドシステム |
DE102006052447A1 (de) | 2006-11-07 | 2008-05-08 | BSH Bosch und Siemens Hausgeräte GmbH | Linearverdichter und Gasdrucklager dafür |
-
2009
- 2009-12-01 JP JP2010542081A patent/JP5110173B2/ja not_active Expired - Fee Related
- 2009-12-01 US US13/124,008 patent/US8763514B2/en active Active
- 2009-12-01 CN CN200980149954.6A patent/CN102245888B/zh not_active Expired - Fee Related
- 2009-12-01 EP EP09831832.2A patent/EP2357348B1/en not_active Not-in-force
- 2009-12-01 WO PCT/JP2009/070143 patent/WO2010067728A1/ja active Application Filing
Patent Citations (8)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US3777722A (en) * | 1969-09-11 | 1973-12-11 | K Lenger | Free piston engine |
JPS61135967A (ja) | 1984-12-04 | 1986-06-23 | Kawasaki Heavy Ind Ltd | 無給油型2サイクルエンジン |
JPH051620A (ja) | 1991-06-26 | 1993-01-08 | Atsugi Unisia Corp | ピストン |
JPH0693927A (ja) | 1992-07-27 | 1994-04-05 | Isuzu Motors Ltd | 内燃機関のピストン |
JP2005520095A (ja) * | 2001-12-18 | 2005-07-07 | デルフィ テクノロジーズ,インコーポレイティド | 対向ピストン式内燃機関 |
JP2005106009A (ja) | 2003-10-01 | 2005-04-21 | Toyota Motor Corp | スターリングエンジン及びそれを備えたハイブリッドシステム |
JP2006161563A (ja) | 2004-12-02 | 2006-06-22 | Honda Motor Co Ltd | 内燃機関のピストン |
JP2006183566A (ja) | 2004-12-27 | 2006-07-13 | Toyota Motor Corp | ピストン装置、スターリングエンジン、及び外燃機関 |
Non-Patent Citations (1)
Title |
---|
See also references of EP2357348A4 * |
Cited By (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JP2012172672A (ja) * | 2011-02-24 | 2012-09-10 | Toyota Motor Corp | スターリングエンジンの気体導入構造 |
JP5528647B1 (ja) * | 2014-02-21 | 2014-06-25 | 信也 ▲高▼原 | ピストン型内燃機関 |
Also Published As
Publication number | Publication date |
---|---|
CN102245888B (zh) | 2014-02-05 |
US20110197755A1 (en) | 2011-08-18 |
JPWO2010067728A1 (ja) | 2012-05-17 |
CN102245888A (zh) | 2011-11-16 |
EP2357348A4 (en) | 2014-05-14 |
US8763514B2 (en) | 2014-07-01 |
EP2357348A1 (en) | 2011-08-17 |
EP2357348B1 (en) | 2015-11-11 |
JP5110173B2 (ja) | 2012-12-26 |
Similar Documents
Publication | Publication Date | Title |
---|---|---|
JP5110173B2 (ja) | ピストンの気体潤滑構造およびスターリングエンジン | |
JP4858424B2 (ja) | ピストン機関及びスターリングエンジン | |
WO2006070832A1 (ja) | ピストン装置、スターリングエンジン、及び外燃機関 | |
JP4285338B2 (ja) | スターリングエンジン | |
JP4650580B2 (ja) | スターリングエンジン | |
JP4289224B2 (ja) | スターリングエンジン | |
JP5418358B2 (ja) | スターリングエンジン | |
JP4059248B2 (ja) | ピストン装置、スターリングエンジン | |
JP2009293406A (ja) | ピストン機関及びスターリングエンジン | |
JP5359606B2 (ja) | スターリングエンジンの冷却器およびスターリングエンジン | |
US8904779B2 (en) | Stirling engine gas lubrication structure | |
JP5391799B2 (ja) | スターリングエンジンの熱交換器およびスターリングエンジン | |
JP2010222992A (ja) | スターリングエンジンのピストンの気体潤滑構造 | |
JP4301082B2 (ja) | ピストン装置 | |
JP2011226440A (ja) | スターリングエンジンの気体潤滑構造 | |
JP4737303B2 (ja) | スターリングエンジン | |
JP4239900B2 (ja) | スターリングエンジン | |
JP2008051117A (ja) | 外燃機関 | |
JP2006183568A (ja) | ピストン機関 | |
JP4337630B2 (ja) | スターリングエンジンの故障診断装置 | |
JP2009127519A (ja) | ピストン機関及びスターリングエンジン | |
JP2005337179A (ja) | スターリングエンジン | |
JP5470946B2 (ja) | スターリングエンジンの熱交換器 | |
JP2011220268A (ja) | スターリングエンジンの作動流体流路構造 | |
JP2005325710A (ja) | 外燃機関のピストン装置及び排気熱回収装置 |
Legal Events
Date | Code | Title | Description |
---|---|---|---|
WWE | Wipo information: entry into national phase |
Ref document number: 200980149954.6 Country of ref document: CN |
|
121 | Ep: the epo has been informed by wipo that ep was designated in this application |
Ref document number: 09831832 Country of ref document: EP Kind code of ref document: A1 |
|
WWE | Wipo information: entry into national phase |
Ref document number: 13124008 Country of ref document: US |
|
WWE | Wipo information: entry into national phase |
Ref document number: 2009831832 Country of ref document: EP |
|
ENP | Entry into the national phase |
Ref document number: 2010542081 Country of ref document: JP Kind code of ref document: A |
|
NENP | Non-entry into the national phase |
Ref country code: DE |