Stirling engine

Abstract

To provide a Stirling engine having a high-pressure gas seal that has a function of an oil seal and is suitable for the Stirling engine.SOLUTION: A Stirling engine 10 with a crosshead mechanism includes a low-pressure space 114 and a high-pressure space 115. In the high-pressure space 115, a piston 112 is driven by a heating / cooling cycle of a working fluid. The low-pressure space 114 accommodates a crosshead portion 116 connected to the piston 112 via a piston rod 118, and a crank mechanism for rotating a crankshaft 113 with movement of the crosshead portion 116. A high-pressure gas seal 119, in which a lip angle of a seal lip on the high-pressure side is smaller than that on the low-pressure side, is provided around the piston rod 118 at a partition portion between the low-pressure space 114 and the high-pressure space 115.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a Stirling engine having a crosshead mechanism. [Background technology]

[0002] In a Stirling engine having a crosshead mechanism, in order to reduce manufacturing costs, an inexpensive material (such as a cylinder block of a general-purpose internal combustion engine) may be used as the crankcase that houses the crank mechanism from the crosshead to the crankshaft. In addition, in a Stirling engine, a high-pressure gas seal is installed on the piston rod to seal the high-pressure gas in the working space so that the high-pressure gas (working fluid) does not leak into the crankcase. At this time, lubricating oil is injected into the piston rod to lubricate the piston rod against the high-pressure gas seal. However, if a large amount of oil enters the working space on the high-pressure side, the heat exchanger becomes clogged and the engine output decreases. Patent Document 1 discloses that an oil scraper is installed to suppress the intrusion of oil into the high-pressure side. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 5945574 Summary of the Invention [Problem to be solved by the invention]

[0004] The configuration of Patent Document 1 requires both a high-pressure gas seal and an oil scraper, which leads to problems such as increased costs. In addition, even with this configuration, it is not possible to completely prevent oil from entering the high-pressure section, and it is also not possible to remove oil that has partially entered the high-pressure side.

[0005] Costs can be reduced by giving the high-pressure gas seal the function of an oil seal and omitting the oil scraper. However, a Stirling engine has a unique condition in that the low-pressure side is the oil-tight side, and for this reason, there are no high-pressure gas seals proposed for Stirling engines in the prior art.

[0006] The present invention has been made in consideration of the above problems, and has an object to provide a Stirling engine having a high-pressure gas seal that functions as an oil seal and is suitable for the Stirling engine. [Means for solving the problem]

[0007] In order to solve the above problems, the Stirling engine of the present invention is a Stirling engine with a crosshead mechanism, and is provided with a high-pressure space that drives a piston by the heating / cooling cycle of a working fluid, a crosshead part connected to the piston via a piston rod, and a low-pressure space that accommodates a crank mechanism that rotates a crankshaft with the movement of the crosshead part, and is characterized in that a gas seal is provided around the piston rod at the partition between the low-pressure space and the high-pressure space, with the lip angle of the seal lip being smaller on the high-pressure side than on the low-pressure side.

[0008] According to the above configuration, the lubricating oil adhering to the piston rod surface is transported to the high pressure side during the retraction stroke of the piston rod (stroke from the bottom dead center position to the top dead center position), but due to the difference in lip angle between the high pressure side and the low pressure side of the gas seal, it is scraped out to the low pressure side by the gas seal. This allows the gas seal to double as an oil seal, making an oil scraper unnecessary, thereby reducing the cost of the Stirling engine.

[0009] Moreover, the Stirling engine may be configured such that the member forming the low pressure space and the member forming the high pressure space are separate members.

[0010] According to the above configuration, the cylinder block of a general-purpose internal combustion engine (e.g., diesel engine) can be used as the member forming the low pressure space (i.e., inexpensive mass-produced parts), and the manufacturing cost of the Stirling engine can be reduced. In addition, the cylinder block of a general-purpose internal combustion engine also includes a crank mechanism and an oil circulation system, which can also be used in the Stirling engine.

[0011] The Stirling engine may be configured such that the crosshead portion is provided with a through hole passing through in the sliding direction thereof.

[0012] With the above configuration, it is possible to prevent the air in the space above the crosshead from being compressed when the crosshead rises, which would cause resistance to the movement of the crosshead. In addition, the lubricating oil that splashes in the low pressure space (inside the crankcase) is sent to the top of the crosshead through the through hole, allowing the gas seal to be well lubricated.

[0013] In the above Stirling engine, the crosshead portion may be configured so as not to include a seal ring between the crosshead portion and a cylinder liner that maintains sliding motion of the crosshead portion.

[0014] According to the above configuration, the absence of a seal ring increases the gap area between the crosshead and the cylinder liner, and the amount of lubricating oil that moves from the crankcase to the top of the crosshead through this gap can be increased. In addition, air can move through the gap between the crosshead and the cylinder liner, which reduces the movement resistance of the crosshead due to air compression.

[0015] The Stirling engine can also be configured to have a splash-type oil circulation system that uses the rotation of the crankshaft to splash lubricating oil accumulated in the lower part of the crankcase to the upper part, a dust seal is disposed below the gas seal, and a first communication passage is provided between the dust seal and the gas seal, connecting the upper part of the dust seal to the low-pressure space.

[0016] According to the above configuration, lubricating oil that accumulates above the dust seal can be released to the low-pressure space through the first communication passage, thereby preventing the adverse effects of oil pressure accumulation caused by the dust seal.

[0017] The Stirling engine can also be configured to have a splash-type oil circulation system that splashes lubricating oil accumulated in the lower part of the crankcase to the upper part by utilizing the rotation of the crankshaft, the gas seals are arranged in multiple stages, a dust seal is arranged in the lower stage of the gas seals, a second communication passage that connects the gas seals arranged in multiple stages with the high-pressure space, and a check valve arranged in the second communication passage.

[0018] According to the above configuration, the lubricating oil that accumulates above the dust seal can be released to the high pressure space through the second communication passage, preventing the adverse effects of oil pressure accumulation caused by the dust seal. In addition, the working fluid that has entered between the gas seals can be returned to the high pressure space, ensuring the gas sealing performance of the high pressure space.

[0019] The Stirling engine may further comprise an oil collection section which collects lubricating oil used to lubricate the gas seal, and an oil supply tank which is connected to the oil collection section via an oil pump and a check valve and into which the lubricating oil is pumped from the oil collection section by the oil pump, and which supplies lubricating oil to the gas seal from above.

[0020] According to the above configuration, by using an oil pump type oil circulation system, compared to a splash type, lubricating oil can be stably supplied to the gas seal regardless of the engine operating state (rotation speed).

[0021] The Stirling engine may be configured so that a water-cooled jacket is provided around the gas seal, and a cooling water circulation system is provided that can supply cooling water to the water-cooled jacket.

[0022] According to the above configuration, the gas seal can be cooled, thereby suppressing thermal expansion of the gas seal due to frictional heat.

[0023] In addition, in the Stirling engine, the cooling water circulation system can be configured to include a bypass path and a bypass valve arranged in the bypass path, and the temperature of the cooling water supplied to the water-cooled jacket can be adjusted by adjusting the opening degree of the bypass valve.

[0024] According to the above-mentioned configuration, the temperature of the gas seal can be controlled within an appropriate temperature range depending on the operating conditions, and the lubrication and sealing properties of the gas seal can be maintained. Effect of the Invention

[0025] The Stirling engine of the present invention has the effect of giving the gas seal an oil seal function (making the gas seal suitable for the Stirling engine) and eliminating the need for an oil scraper, thereby reducing the cost of the Stirling engine. [Brief description of the drawings]

[0026] [Figure 1] FIG. 1 is a schematic diagram showing a general configuration of a Stirling engine. [Diagram 2] FIG. 1 is a schematic diagram showing a schematic configuration of an engine section of a Stirling engine. [Diagram 3] FIG. 1(a) is a schematic diagram showing the structure when a general rod seal is used as a high-pressure gas seal, and FIG. 1(b) is a schematic diagram showing the structure of a high-pressure gas seal according to one embodiment of the present invention. [Figure 4] FIG. 11 is a schematic diagram showing an oil supply mechanism according to a third embodiment. [Diagram 5] FIG. 11 is a schematic diagram showing a configuration in the vicinity of a high-pressure gas seal in a fourth embodiment. [Figure 6] FIG. 11 is a schematic diagram showing a configuration in the vicinity of a high-pressure gas seal in a fourth embodiment. [Figure 7] FIG. 11 is a schematic diagram showing a cooling water circulation system according to a fifth embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0027] [First embodiment] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings. Fig. 1 is a schematic diagram showing a schematic configuration of a Stirling engine 10. As shown in Figs.

[0028] 1, a Stirling engine 10 has an engine section 11, a heater heat exchanger 12, a regenerator 13, and a cooler heat exchanger 14. In the Stirling engine 10, a generator (not shown) is connected to a crankshaft 113 of the engine section 11, and the Stirling engine 10 can drive the generator to generate electricity.

[0029] In the Stirling engine 10, a heater heat exchanger 12 is inserted into a high-temperature heat source (e.g., a high-temperature pipe through which a high-temperature fluid flows), and a working fluid (e.g., helium gas) is heated in the heater heat exchanger 12. Furthermore, in the cooler heat exchanger 14, the working fluid is cooled by cooling water (means for supplying the cooling water is not shown). The Stirling engine 10 is configured to drive an engine section 11 by the movement of the working fluid thus heated / cooled. The engine section 11 may be a single-cylinder type engine or a multi-cylinder type engine, but in the present embodiment 1, a four-cylinder double-acting engine is exemplified.

[0030] As shown in FIG. 3, the engine unit 11 has four cylinders 111-1 to 111-4 (simply referred to as cylinders 111 when no particular distinction is made). Here, the four cylinders arranged in a straight line with respect to the crankshaft 113 are referred to as cylinders 111-1 to 111-4 in the order of their arrangement. Each cylinder 111 is provided with a piston 112, and a high-temperature chamber 111a is provided on one side (upper side in FIG. 1) of the sliding direction of the piston 112 (vertical direction in FIG. 1), and a low-temperature chamber 111b is provided on the other side (lower side in FIG. 1). The high-temperature chamber 111a is connected to the heater heat exchanger 12, and the low-temperature chamber 111b is connected to the cooler heat exchanger 14. The heater heat exchanger 12 and the cooler heat exchanger 14 are connected with a regenerator 13 sandwiched therebetween. The regenerator 13 serves as a heat storage means between the heater heat exchanger 12 and the cooler heat exchanger 14, storing heat from the working fluid when the working fluid moves from the heater heat exchanger 12 to the cooler heat exchanger 14 and recovering the heat to the working fluid when the working fluid flows in the opposite direction, thereby making effective use of the heat. In the four-cylinder double-acting engine illustrated in Fig. 1, the heater heat exchanger 12 and the cooler heat exchanger 14, which are connected with the same regenerator 13 sandwiched therebetween, are each connected to a different cylinder 111.

[0031] The operation of the Stirling engine 10 is achieved by repeating a cycle in which the piston 112 in each cylinder 111 sequentially takes a first position (top dead center position: cylinder 111-1 in FIG. 1), a second position (a position at which the crankshaft 113 is rotated 90° from the top dead center position while the piston 112 moves downward: cylinder 111-4 in FIG. 1), a third position (bottom dead center position: cylinder 111-3 in FIG. 1), and a fourth position (a position at which the crankshaft 113 is rotated 90° from the bottom dead center position while the piston 112 moves upward: cylinder 111-2 in FIG. 14).

[0032] FIG. 2 is a schematic diagram showing a schematic configuration of the engine section 11 in the Stirling engine 10. The engine section 11 in FIG. 2 uses a cylinder block of a general-purpose internal combustion engine (e.g., a diesel engine) as part of its structure in order to reduce manufacturing costs, and is a crosshead mechanism that uses a piston part of the general-purpose internal combustion engine as a crosshead section 116. That is, in the engine section 11 in FIG. 2, a low-pressure space 114 is formed by the cylinder block of the general-purpose internal combustion engine, and the crosshead section 116 is disposed in the low-pressure space 114. In addition, in the low-pressure space 114, the crosshead section 116 is connected to a crankshaft 113 via a connecting rod 117. The crank mechanism (i.e., a mechanism consisting of the crosshead section 116, the connecting rod 117, and the crankshaft 113) that rotates the crankshaft 113 as the crosshead section 116 moves is also used from the cylinder block of the general-purpose internal combustion engine.

[0033] A high-pressure space 115 (both the high-temperature chamber 111a and the low-temperature chamber 111b in FIG. 1 are included in the high-pressure space 115) of each cylinder 111 is provided above the low-pressure space 114, and a piston 112 is disposed in the high-pressure space 115. That is, in the high-pressure space 115, the piston 112 is driven by the heating / cooling cycle of the working fluid. The high-pressure space 115 is formed of a separate member from the cylinder block of the general-purpose internal combustion engine that forms the low-pressure space 114. The piston 112 and the crosshead portion 116 are connected by a piston rod 118. That is, the piston 112, the piston rod 118, and the crosshead portion 116 reciprocate integrally along a predetermined sliding direction (the up-down direction in FIG. 2).

[0034] At the partition between the low pressure space 114 and the high pressure space 115, a high pressure gas seal (gas seal) 119 is installed around the piston rod 118 to prevent the working fluid from leaking from the high pressure space 115 to the low pressure space 114. In addition, oil (lubricating oil) is supplied to the high pressure gas seal 119 to lubricate between the piston rod 118 and the high pressure gas seal 119. For this reason, the oil supplied from the crankcase to the bearings and the like is also supplied to the piston rod 118. The oil circulation system built into the cylinder block of the general-purpose internal combustion engine can be used as the oil supply mechanism for such high pressure gas seal 119. The built-in oil circulation system may be of an oil pump type or a splash type (a type in which oil collected in an oil pan at the bottom of the crankcase is splashed upward by utilizing the rotation of the crankshaft).

[0035] It is preferable that the high-pressure gas seal 119 also serves as an oil seal to prevent oil from entering the high-pressure space 115 from the low-pressure space 114, and it is possible to use a rod seal used in general hydraulic equipment. In general hydraulic equipment, the high-pressure side is the oil-tight side, so if an existing rod seal used in hydraulic equipment is used as the high-pressure gas seal 119 as it is, as shown in Fig. 3(a), the lip angle of the seal lip (the angle between the lip surface and the rod surface in a cross section passing through the central axis of the piston rod 118) is made larger on the high-pressure side than on the low-pressure side (α>β in Fig. 3(a)), resulting in a structure that prevents oil from entering from the high-pressure side to the low-pressure side. Specifically, the oil film on the surface of the piston rod 118 that is generated above and below the high-pressure gas seal 119 due to the reciprocating motion of the piston rod 118 becomes thinner on the side of the high-pressure gas seal 119 with a smaller lip angle (low-pressure side) and thicker on the side of the high-pressure gas seal 119 with a larger lip angle (high-pressure side), thereby preventing oil from entering from the high-pressure side to the low-pressure side.

[0036] On the other hand, in the Stirling engine 10, the low pressure side is the oil-tight side, which is the opposite of a general hydraulic device, so the high pressure gas seal 119 needs to prevent oil from entering from the low pressure side to the high pressure side. For this reason, if an existing rod seal is used as the high pressure gas seal 119, oil will enter from the low pressure side to the high pressure side. As a result, oil is intermittently sent from the low pressure space 114 to the high pressure space 115, causing clogging of the heat exchangers (heater heat exchanger 12 and cooler heat exchanger 14) and causing a decrease in output, as well as the risk of the oil in the crankcase drying up and causing the drive parts to burn out.

[0037] In order to solve the above problems and allow the high-pressure gas seal 119 to function as an oil seal as well, in the Stirling engine 10 according to the first embodiment, the high-pressure gas seal 119 in the engine section 11 has a lip angle of the seal lip made smaller on the high-pressure side than on the low-pressure side (α<β in FIG. 3(b)), as shown in FIG. 3(b), to prevent oil from entering from the low-pressure side to the high-pressure side.

[0038] 3(a) and (b) denotes an O-ring, which is used to adjust the contact pressure (surface pressure) of the high-pressure gas seal 119 against the piston rod 118. The gas sealing performance of the high-pressure gas seal 119 against the working fluid is obtained by the surface pressure of the high-pressure gas seal 119, and the gas sealing performance of the high-pressure gas seal 119 having the structure shown in Fig. 3(b) can be equivalent to that of the high-pressure gas seal 119 in Fig. 3(a).

[0039] In the configuration of FIG. 3(b), the oil that has entered the minute unevenness on the surface of the piston rod 118 is transported to the high pressure side during the retraction stroke of the piston rod 118 (stroke from the bottom dead center position to the top dead center position). However, due to the difference in lip angle between the high pressure side and the low pressure side of the high pressure gas seal 119, the oil film on the surface of the piston rod 118 is thicker on the side of the high pressure gas seal 119 with a larger lip angle (low pressure side) and thinner on the side of the high pressure gas seal 119 with a smaller lip angle (high pressure side). As a result, the oil on the surface of the piston rod 118 is scraped out to the low pressure side by the high pressure gas seal 119. This makes it possible to prevent the oil from entering and accumulating on the high pressure side. In addition, since the high pressure gas seal 119 also serves as an oil seal, an oil scraper is not required, and the cost of the Stirling engine 10 can be reduced.

[0040] [Embodiment 2] As described above, the engine section 11 of the Stirling engine 10 uses a cylinder block of a general-purpose internal combustion engine, and the piston parts of the general-purpose internal combustion engine are used as the crosshead section 116. In this case, if the piston parts of the general-purpose internal combustion engine are used as the crosshead section 116 as they are, the air in the upper space of the crosshead section 116 will be compressed in the low pressure space 114 when the crosshead section 116 rises. This causes a movement resistance in the crosshead section 116, and the output of the Stirling engine 10 will decrease.

[0041] To prevent this, the crosshead part 116 is provided with (preferably multiple) through holes 116a (see FIG. 2) that penetrate along the sliding direction. By providing the through holes 116a in the crosshead part 116, the movement resistance of the crosshead part 116 can be reduced, and a decrease in the output of the Stirling engine 10 can be prevented.

[0042] Furthermore, the engine section 11 utilizes an oil circulation system provided in the cylinder block of a general-purpose internal combustion engine to supply oil to the high-pressure gas seal 119. However, the oil circulation system provided in the general-purpose internal combustion engine (particularly, a splash-type oil circulation system) is originally intended to supply oil to the piston parts (i.e., the crosshead section 116) and the bearings of the crank mechanism of the general-purpose internal combustion engine, and is not intended to supply oil to the high-pressure gas seal 119 located above the crosshead section 116.

[0043] In response to this, by providing through-hole 116a in crosshead portion 116, oil scattering within low pressure space 114 (inside the crankcase) can be sent to the upper part of crosshead portion 116 through through-hole 116a, and the oil can be attached to piston rod 118 to lubricate high pressure gas seal 119. This makes it possible to prevent abnormal wear of high pressure gas seal 119. Note that it is preferable that a plurality of through-holes 116a are provided at equal angular intervals along the circumferential direction of crosshead portion 116.

[0044] In addition, piston parts for general-purpose internal combustion engines are usually fitted with seal rings on the piston side to serve as gas seals or oil seals. However, in the crosshead part 116 using this piston part, it is preferable to remove these seal rings before use. This increases the gap area between the crosshead part 116 and the cylinder liner that keeps the crosshead part 116 sliding, and the amount of oil moving from the crankcase to the top of the crosshead part 116 can also be increased through this gap. In addition, because air can move through the gap between the crosshead part 116 and the cylinder liner, the movement resistance of the crosshead part 116 due to air compression can also be reduced.

[0045] Third Embodiment In the third embodiment, a description will be given of a suitable example of an oil supply mechanism to the high pressure gas seal 119. Fig. 4 is a schematic diagram of the oil supply mechanism according to the third embodiment.

[0046] 4 utilizes an oil pump type oil circulation system, and has a configuration in which oil used to lubricate the high pressure gas seal 119 is collected in an oil pan (oil collection section) 131 (which may be an oil tank), and the oil pan 131 and a gas seal oil supply tank (oil supply tank) 130 are connected via a high pressure oil pump (oil pump) 132 and a check valve 133. Furthermore, an oil communication passage 135 that supplies oil to the upper part of the high pressure gas seal 119 via a throttle 134, and a communication port 136 for balancing the pressure with the high pressure space 115 are connected from the gas seal oil supply tank 130.

[0047] In the oil supply mechanism of Fig. 4, the high-pressure oil pump 132 is operated constantly or periodically, and a constant amount of oil is sent from the oil pan 131 to the gas seal oil supply tank 130. Then, the oil in the gas seal oil supply tank 130 is supplied to the high-pressure gas seal 119 through the oil communication passage 135. At this time, the oil communication passage 135 supplies oil to the upper part of the high-pressure gas seal 119, i.e., the high-pressure space 115 side. However, by configuring the high-pressure gas seal 119 as shown in Fig. 3(b), the oil that accumulates at the upper part of the high-pressure gas seal 119 is transferred from the high-pressure side to the low-pressure side with the reciprocating motion of the piston rod 118, and the oil does not accumulate in the high-pressure space 115.

[0048] The oil supply mechanism in FIG. 4 utilizes an oil pump type oil circulation system, and can supply oil stably to the high-pressure gas seal 119 regardless of the engine operating state (rotation speed) compared to a splash type.

[0049] Fourth embodiment Lubricating oil may contain foreign matter (so-called contaminants). In particular, when a splash-type oil supply mechanism is employed, foreign matter may reach the high-pressure gas seal 119, and the foreign matter may become caught and wear out the high-pressure gas seal 119, or foreign matter may enter the high-pressure space 115. For this reason, as shown in FIG. 5, a dust seal 140 is disposed below the high-pressure gas seal 119 (on the low-pressure side relative to the high-pressure gas seal 119), and the dust seal 140 removes the foreign matter from the oil before it reaches the high-pressure gas seal 119.

[0050] However, simply providing the dust seal 140 makes it difficult for oil accumulated on the upper part of the dust seal 140 to flow downward (the dust seal 140 reduces the speed at which oil adhering to the surface of the piston rod 118 flows downward). Therefore, the use of the dust seal 140 may cause a phenomenon in which oil accumulates between the dust seal 140 and the high-pressure gas seal 119, resulting in high oil pressure (oil pressure accumulation). In addition, in some cases, the high-pressure gas seals 119 are provided in multiple stages (two stages in FIG. 5) in order to extend the maintenance interval of the parts, but in this case, oil pressure accumulation may occur between the high-pressure gas seals 119 arranged in multiple stages. When such oil pressure accumulation occurs, the high-pressure gas seal 119 may be tilted from the correct position due to the oil pressure, which may reduce the sealing performance of the high-pressure gas seal 119 or cause abnormal wear of the high-pressure gas seal 119.

[0051] 5 is configured to provide a communication passage (first communication passage) 141 between the dust seal 140 and the high-pressure gas seal 119, connecting the upper part of the dust seal 140 with the low-pressure space 114. With this configuration, oil that accumulates above the dust seal 140 is released to the low-pressure space 114 through the communication passage 141, thereby preventing oil pressure accumulation. As a result, the attitude of the high-pressure gas seal 119 is stabilized, good sealing performance is ensured, and abnormal wear of the high-pressure gas seal 119 can be prevented.

[0052] Furthermore, when high-pressure gas seals 119 are provided in multiple stages, in order to prevent oil pressure accumulation between the high-pressure gas seals 119, a communication passage (second communication passage) 142 connecting the gap between the high-pressure gas seals 119 and the high-pressure space 115 may be provided, and a check valve 143 may be provided in the communication passage 142, as shown in Fig. 6. In the configuration of Fig. 6, in addition to being able to prevent pressure accumulation between the high-pressure gas seals, the working fluid that has entered between the high-pressure gas seals 119 can be returned to the high-pressure space 115, so that the gas sealing performance of the high-pressure space 115 can be ensured.

[0053] Fifth embodiment In the Stirling engine 10, a part of the heat absorbed from the high-temperature heat source is released to the external environment via the cooler heat exchanger 14. In a waste heat recovery Stirling engine intended to recover waste heat from a factory or the like, it is common to use external cooling water from the installation facility (customer's facility) or its circulation system as the cooler cooling water. However, such a method requires the customer to bear the costs of the cooling water and modifications to the customer's facility (modification of the facility to supply cooling water to the cooler heat exchanger 14).

[0054] On the other hand, the Stirling engine 10 uses the cylinder block of a general-purpose internal combustion engine as part of its configuration, and diesel engines and the like usually have a cooling water circulation system as an existing system. In this fifth embodiment, a description will be given of a Stirling engine 10 equipped with a cooling water circulation system that uses existing parts that are equipped in a general-purpose internal combustion engine.

[0055] FIG. 7 is a schematic diagram showing a cooling water circulation system according to the fifth embodiment. The cooling water circulation system of FIG. 7 uses a circulation pump 150, a radiator 151, and a cooling fan 152 as existing parts provided in a general-purpose internal combustion engine. The circulation pump 150 is a drive source for circulating the cooling water. The radiator 151 is a heat exchanger for dissipating heat from the cooling water. The cooling fan 152 blows air on the radiator 151 to promote heat dissipation, and is connected to one end of the crankshaft 113. This cooling water circulation system has a cooling water path that can supply cooling water to at least the cooler heat exchanger 14.

[0056] As shown in Fig. 7, the Stirling engine 10 according to the fifth embodiment has a cooling water path that can supply cooling water to at least the cooler heat exchanger 14. In addition, this cooling water circulation system can circulate the cooling water by including the radiator 151 and the cooling fan 152, and does not require external cooling water. This makes it possible to eliminate the cost of cooling water and the need to modify the customer's equipment.

[0057] In addition, the cooling water circulation system according to the fifth embodiment can be used for cooling other than the cooler heat exchanger 14, for example, for cooling the high-pressure gas seal 119 or the cylinder 111 in the high-pressure space 115.

[0058] Since the resin high-pressure gas seal 119 has a high linear expansion coefficient, there is a concern that it will expand due to frictional heat and increase the binding force of the piston rod 118. In this case, the oil film thickness will decrease and the seal will wear out early. For this reason, it is preferable that the temperature of the high-pressure gas seal 119 be controlled within an appropriate temperature range according to the operating conditions.

[0059] 7, a water-cooled jacket 160 is provided around the high-pressure gas seal 119, and a cooling water path is provided that can supply cooling water to the water-cooled jacket 160 as well. This makes it possible to suppress thermal expansion of the high-pressure gas seal 119. Furthermore, the cooling water circulation system of FIG. 7 is provided with a bypass path 161 and a bypass valve 162 in part of the cooling water path.

[0060] In this example, the bypass path 161 is configured to supply, upstream of the water-cooled jacket 160, cooling water having a lower temperature than the cooling water path that merges with the bypass path 161. In this configuration, it is possible to adjust the high-pressure gas seal 119 to an appropriate temperature by adjusting the opening of the bypass valve 162. Specifically, by increasing the opening of the bypass valve 162 and increasing the amount of cooling water supplied to the water-cooled jacket 160 via the bypass path 161, the cooling effect of the high-pressure gas seal 119 can be improved.

[0061] Furthermore, in the cylinder 111 in the high pressure space 115 of the Stirling engine 10, oil lubrication of the piston 112 is not possible, so metal rings as used in internal combustion engines cannot be used. For this reason, a resin ring with high solid lubricity is used to lubricate the piston 112 and the inner wall of the cylinder 111. However, the resin ring has a risk of being weakened or damaged by heat received from the high pressure space 115.

[0062] 7, a water-cooled jacket 163 for high-temperature cylinders is provided around the cylinder 111, and a cooling water path is provided to supply cooling water to the water-cooled jacket 163. This allows the resin ring used to lubricate the piston 112 to be cooled by the cooling water circulation system, preventing the resin ring from losing strength or being damaged.

[0063] 7, the cooling water path passes the cooling water that has received heat dissipation in the radiator 151 through the cooler heat exchanger 14, the water-cooled jacket 163, and the water-cooled jacket 160 in this order. In this case, the bypass path 161 is arranged between the water-cooled jackets 163 and 160 to bypass and supply cooling water that is lower in temperature than after passing through the cooler heat exchanger 14 and the water-cooled jacket 163.

[0064] The embodiments disclosed herein are illustrative in all respects and are not intended to be limiting. Therefore, the technical scope of the present invention is not interpreted solely by the above-described embodiments, but is defined by the claims. Also, all modifications within the scope and meaning equivalent to the claims are included. [Explanation of symbols]

[0065] 10. Stirling Engine 11 Engine section 111 cylinders 111a High temperature chamber 111b Cold room 112 Piston 113 Crankshaft 114 Low Pressure Space 115 High Pressure Space 116 Crosshead section 116a Through hole 117 Connecting rod 118 Piston rod 119 High pressure gas seal (gas seal) 120 O-ring 130 Gas seal oil tank (oil tank) 131 Oil pan (oil collection part) 132 High pressure oil pump (oil pump) 133 Check valve 134 Aperture 135 Oil passage 136 Connecting port 140 Dust seal 141 Passageway (1st Passageway) 142 Passageway (Second Passageway) 150 Circulation Pump 151 Radiator 152 Cooling fan 160 Water-cooling jacket 161 Bypass Route 162 Bypass valve 163 Water-cooling jacket 12 Heater heat exchanger 13 Regenerator 14 Cooler heat exchanger

Claims

1. A Stirling engine having a crosshead mechanism, a high pressure space that drives a piston by a heating / cooling cycle of a working fluid; a low-pressure space that accommodates a crosshead portion connected to the piston via a piston rod and a crank mechanism that rotates a crankshaft in accordance with the movement of the crosshead portion, a gas seal is provided around the piston rod at a partition between the low pressure space and the high pressure space, the lip angle of the seal lip being smaller on the high pressure side than on the low pressure side, The oil circulation system splashes the lubricating oil accumulated in the lower part of the crankcase to the upper part by utilizing the rotation of the crankshaft. a dust seal is disposed below the gas seal, and a first communication passage is provided between the dust seal and the gas seal, the first communication passage connecting an upper portion of the dust seal to the low pressure space.

2. A Stirling engine having a crosshead mechanism, a high pressure space that drives a piston by a heating / cooling cycle of a working fluid; a low-pressure space that accommodates a crosshead portion connected to the piston via a piston rod and a crank mechanism that rotates a crankshaft in accordance with the movement of the crosshead portion, a gas seal is provided around the piston rod at a partition between the low pressure space and the high pressure space, the lip angle of the seal lip being smaller on the high pressure side than on the low pressure side, The oil circulation system splashes the lubricating oil accumulated in the lower part of the crankcase to the upper part by utilizing the rotation of the crankshaft. a second communication passage that connects between the gas seals provided in the multiple stages and the high-pressure space, and a check valve that is provided in the second communication passage.

3. A Stirling engine having a crosshead mechanism, a high pressure space that drives a piston by a heating / cooling cycle of a working fluid; a low-pressure space that accommodates a crosshead portion connected to the piston via a piston rod and a crank mechanism that rotates a crankshaft in accordance with the movement of the crosshead portion, a gas seal is provided around the piston rod at a partition between the low pressure space and the high pressure space, the lip angle of the seal lip being smaller on the high pressure side than on the low pressure side, an oil collecting section for collecting lubricating oil used for lubricating the gas seal; an oil supply tank connected to the oil collecting section via an oil pump and a check valve, into which the lubricating oil is pumped from the oil collecting section by the oil pump; A Stirling engine, wherein the oil tank supplies lubricating oil to the gas seal from above.

4. A Stirling engine having a crosshead mechanism, a high pressure space that drives a piston by a heating / cooling cycle of a working fluid; a low-pressure space that accommodates a crosshead portion connected to the piston via a piston rod and a crank mechanism that rotates a crankshaft in accordance with the movement of the crosshead portion, a gas seal is provided around the piston rod at a partition between the low pressure space and the high pressure space, the lip angle of the seal lip being smaller on the high pressure side than on the low pressure side, A Stirling engine comprising: a water-cooled jacket provided around the gas seal; and a cooling water circulation system capable of supplying cooling water to the water-cooled jacket.

5. A Stirling engine according to any one of claims 1 to 4, A Stirling engine, characterized in that the crosshead portion is provided with a through hole extending along the sliding direction thereof.

6. A Stirling engine according to any one of claims 1 to 5, A Stirling engine, characterized in that the crosshead portion does not have a seal ring between the crosshead portion and a cylinder liner that maintains sliding of the crosshead portion.

7. 5. A Stirling engine according to claim 4, The cooling water circulation system of the Stirling engine is characterized in that it includes a bypass path and a bypass valve arranged in the bypass path, and the temperature of the cooling water supplied to the water-cooled jacket can be adjusted by adjusting the opening degree of the bypass valve.

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