Reciprocating pump

Abstract

To provide a reciprocating pump capable of improving a pumping amount and a suction amount per hour by increasing the speed of reciprocating movement of a piston compared to conventional reciprocating pumps.SOLUTION: A reciprocating pump 1 comprises a cylindrical cylinder 10, a piston 20 capable of reciprocating inside the cylinder 10, and a piston ring 30 that is fixed to the piston 20 and whose outer periphery is in contact with the inner wall of the cylinder 10. At least a portion of the piston ring 30 that is in contact with the inner wall of the cylinder 10 is made of a material using a natural resin. By using a natural resin with excellent thermal characteristics and fracture characteristics, the reciprocating pump 1 is able to increase the reciprocating speed of the piston compared to conventional reciprocating pumps, thereby improving a pumping amount and a suction amount per hour.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a reciprocating pump. [Background technology]

[0002] Conventionally, a reciprocating pump has been known that includes a cylindrical cylinder, a piston that can reciprocate inside the cylinder, and a piston ring that is fixed to the piston and whose outer periphery is in contact with the inner wall of the cylinder (see, for example, Patent Document 1).

[0003] While reciprocating pumps having the above-described configuration have been widely known for some time, recent technological advances have led to the miniaturization and improved performance of reciprocating pumps and their associated devices, leading to their use in an even wider variety of fields. For example, reciprocating pumps as compression devices are used as part of or connected to tire pumps, air sprayers, oxygen concentrators, ventilators, on-board compressors, and thermal management systems for electric vehicles (EVs) (particularly those related to temperature control using heat exchange technology in air conditioning, batteries, drive control circuits, etc.). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2001-280250 Summary of the Invention [Problem to be solved by the invention]

[0005] One approach to improving the performance of reciprocating pumps is to increase the pumping or suction volume per unit time by increasing the reciprocating speed of the piston. However, simply increasing the reciprocating speed of the piston can cause significant (possibly irreversible) deformation of the piston rings due to increased frictional and compression heat, which can lead to an inability to maintain airtightness within the cylinder. For this reason, conventional reciprocating pumps have limitations on how fast the piston can be reciprocated, making it difficult to improve the pumping or suction volume per unit time (and thus the resulting pressure).

[0006] Therefore, the present invention has been made in consideration of the above-mentioned problems, and aims to provide a reciprocating pump that can improve the pumping volume and suction volume per unit time by increasing the speed of reciprocating piston movement compared to conventional reciprocating pumps. [Means for solving the problem]

[0007] In general reciprocating pumps, piston rings made of synthetic resins, such as petroleum-based or silicon-based resins, or synthetic rubber are used due to factors such as cost and availability. In addition to synthetic resins, other known resins include naturally occurring resins such as cashew-based resins and lacquer-based resins. However, naturally occurring resins are primarily used in the field of crafts as paint components, and due to issues such as their properties (e.g., allergies and curing time) and availability, they have rarely been considered as materials for components in industrially mass-produced products such as reciprocating pumps.

[0008] Here, we will explain natural resins in more detail. Lacquer-based resins, a well-known natural resin, are primarily used as a component of paint in lacquerware. Lacquerware is a culture that emphasizes the technical value of producing products by applying paint containing lacquer, a natural resin, to wood with a brush. From a practical standpoint, the purpose of applying lacquer-containing paint to wood is to provide water repellency and durability to compensate for the wood's shortcomings. In the field of industrial products, new materials that have become available due to technological advances, particularly petroleum-based synthetic resins that are cheaper and easier to process than wood, have become popular, and it can be said that products made from wood are in decline. As a result, the technical value of lacquerware is also declining.

[0009] Furthermore, when using paints containing lacquer in the manufacture of industrial products, hand application is not a realistic choice from the perspective of production efficiency. Spray application using a spray gun is a common application method in the industrial product field, but spray application of lacquer-containing paints poses the problem of worker restrictions due to the allergenic nature of lacquer. Furthermore, paints containing lacquer pose problems, such as the need to adjust drying and curing conditions (temperature and temperature control are required for enzymatic oxidation curing) and the length of drying and curing time (basically natural drying). For this reason, lacquer-based resins have not been accepted in the industrial product field, where handling and cost of materials and manufacturing methods are important.

[0010] Cashew-based resins are also available as naturally derived resins, but they were originally developed to replace lacquer-based resins in light of issues related to their productivity (such as declining reforestation, labor shortages, and rising prices). For this reason, cashew-based resins have been used mainly in the field of crafts as a substitute for lacquer-based resins, and have not been accepted in the field of industrial products.

[0011] However, as a result of intensive research by the inventors of the present invention, it was discovered for the first time that naturally occurring resins such as cashew-based resin and lacquer-based resin have excellent thermal properties (particularly heat resistance and thermal conductivity) and high breaking strength. The present invention is based on this research and has the following features.

[0012] [1] The reciprocating pump of the present invention is a reciprocating pump comprising a cylindrical cylinder, a piston capable of reciprocating within the cylinder, and a piston ring fixed to the piston and having an outer periphery in contact with the inner wall of the cylinder, wherein at least the portion of the piston ring in contact with the inner wall of the cylinder is made of a material using a naturally occurring resin.

[0013] [2] In one embodiment of the reciprocating pump of the present invention, the piston ring is preferably made entirely of a material using the naturally occurring resin.

[0014] [3] In one embodiment of the reciprocating pump of the present invention, the naturally derived resin preferably contains a cashew-based resin as a main component.

[0015] [4] In one embodiment of the reciprocating pump of the present invention, the naturally occurring resin preferably contains a lacquer resin as a main component.

[0016] [5] In one embodiment of the reciprocating pump of the present invention, the material using the naturally occurring resin is preferably the naturally occurring resin to which a silicone-based material has been added.

[0017] [6] In one embodiment of the reciprocating pump of the present invention, the material using the naturally occurring resin is preferably the naturally occurring resin to which carbon powder has been added.

[0018] [7] In one embodiment of the reciprocating pump of the present invention, the material using the naturally occurring resin is preferably a carbon fiber reinforced plastic using the naturally occurring resin as a matrix material.

[0019] [8] In one embodiment of the reciprocating pump of the present invention, the matrix material is preferably made of a resin obtained by adding a silicone-based material to the naturally occurring resin.

[0020] [9] In one embodiment of the reciprocating pump of the present invention, the matrix material is preferably made of a resin obtained by adding carbon powder to the naturally occurring resin. [Effects of the Invention]

[0021] In the reciprocating pump of the present invention, at least the portion of the piston ring that contacts the inner wall of the cylinder is made of a material using a natural resin. Therefore, by using a natural resin that has excellent thermal and fracture properties, the reciprocating pump of the present invention can achieve higher pumping and suction volumes per hour due to faster reciprocating motion of the piston compared to conventional reciprocating pumps. [Brief explanation of the drawings]

[0022] [Figure 1] 1A and 1B are diagrams illustrating a reciprocating pump 1 according to a first embodiment. [Figure 2] 2 is a cross-sectional view illustrating the operation of the reciprocating pump 1 according to the first embodiment. FIG. [Figure 3] FIG. 1 is a diagram illustrating a thermal conductivity test piece 100 constructed for measuring the thermal conductivity of a naturally occurring resin (cashew-based resin) and an epoxy-based resin. [Figure 4] 1 is a bar graph showing the thermal conductivity of a naturally derived resin (cashew-based resin) and an epoxy-based resin. [Figure 5] 1 is a photograph showing test results regarding the heat resistance of a naturally derived resin (cashew-based resin) and an epoxy-based resin. [Figure 6] 3A to 3C are views for explaining a manufacturing method of the piston ring 30 in the first embodiment. [Figure 7] 10 is a diagram illustrating a reciprocating pump 2 according to a second embodiment. FIG. [Figure 8]10A and 10B are diagrams illustrating a reciprocating pump 3 according to a modified example. [Figure 9] 10A and 10B are diagrams illustrating a reciprocating pump 4 according to a modified example. DETAILED DESCRIPTION OF THE INVENTION

[0023] The reciprocating pump of the present invention will be described below based on the embodiments shown in the drawings. In each embodiment described below, components having the same or substantially the same functions will be designated by common reference numerals even if their shapes are slightly different, and descriptions already given may be omitted. The embodiments described below do not limit the invention according to the claims. Furthermore, not all of the elements and combinations thereof described in each embodiment are necessarily essential to the solution of the present invention.

[0024] [Embodiment 1] 1. Reciprocating Pump 1 FIG. 1 is a diagram illustrating a reciprocating pump 1 according to a first embodiment. FIG. 1(a) is a cross-sectional view of the reciprocating pump 1 taken along a plane including the central axis A of the cylinder 10, FIG. 1(b) is a plan view of a piston ring 30, and FIG. 1(c) is a cross-sectional view taken along B1-B1 of FIG. 1(b). In FIG. 1(a), the piston 20, connecting rod 70, and pin 72 are shown as front views rather than cross-sectional views. This also applies to cross-sectional views of other reciprocating pumps, which will be described later. All of the drawings illustrating the reciprocating pump and its components, including FIG. 1, are schematic diagrams. 2A to 2D are cross-sectional views illustrating the operation of the reciprocating pump 1 according to the embodiment 1. FIGS. 2A to 2D are cross-sectional views illustrating the steps in the operation cycle of the reciprocating pump 1.

[0025] The reciprocating pump 1 according to the first embodiment is a reciprocating pump. When used as a device for pumping fluid or as part of such a device, the reciprocating pump 1 can be said to be a compressor (pumping device), and when used as a device for sucking fluid or as part of such a device, the reciprocating pump 1 can be said to be a suction device (vacuum pump).

[0026] As shown in Fig. 1, the reciprocating pump 1 includes a cylinder 10, a piston 20, and a piston ring 30. In addition to the above-described components, the reciprocating pump 1 also includes a piston ring fixing member 36, an intake valve 40, an exhaust valve 50, a main shaft 60, and a connecting rod 70. The reciprocating pump 1 may also include other components. Each component will be described below.

[0027] The cylinder 10 is a cylindrical member. In this specification, "cylindrical" means having a columnar internal space. The cylinder 10 has an internal space in which the piston 20 reciprocates. The cylinder 10 also has an intake port 12 connected to the intake valve 40 and an exhaust port 14 connected to the exhaust valve 50. The intake port 12 and the exhaust port 14 of the reciprocating pump 1 are located on the same side as seen from the piston 20.

[0028] It should be noted that the terms "intake" and "exhaust" used in this specification do not limit the type of fluid pumped or sucked by the reciprocating pump 1 to gas. For example, if the reciprocating pump 1 pumps or sucks water, the terms can be replaced with "water intake" and "drain." The terms can also be replaced with "intake" and "exhaust," which are terms that do not depend on the type of fluid.

[0029] The piston 20 is a member that can reciprocate inside the cylinder 10. The outer shape of the piston 20 corresponds to the shape of the internal space of the cylinder 10, but the piston 20 does not directly contact the inner wall of the cylinder 10.

[0030] The piston ring 30 is a component fixed to the piston 20, the outer periphery of which is in contact with the inner wall of the cylinder 10. The piston ring 30 is dish-shaped, with a through-hole 31 formed in the center (see FIGS. 1(b) and 1(c)). The thickness of the piston ring 30 may be, for example, 0.1 mm to 1 mm. At least the portion of the piston ring 30 that is in contact with the inner wall of the cylinder 10 is made of a material using a naturally-derived resin, and more specifically, the entire piston ring 30 is made of a material using a naturally-derived resin. Details of the "naturally-derived resin" and the "material using a naturally-derived resin" will be described later.

[0031] The piston ring fixing member 36 is a member arranged on the opposite side of the piston ring 30 from the piston 20, and fixes the piston ring 30 to the piston 20. In this case, the through hole 31 can be used as a hole for passing the piston ring fixing member 36 and a fixing device (for example, a bolt, not shown) for fixing the piston ring fixing member 36 to the piston 20.

[0032] The intake valve 40 is a valve that has the function of allowing fluid to pass when the piston 20 moves away from the intake port 12 and not allowing fluid to pass when the piston 20 moves toward the intake port 12. Such intake valves are well known, and therefore a detailed description thereof will be omitted.

[0033] The exhaust valve 50 is a valve that does not allow fluid to pass when the piston 20 moves away from the exhaust port 14, but allows fluid to pass when the piston 20 moves toward the exhaust port 14. Such exhaust valves are well known, so a detailed description will be omitted. The intake valve 40 and the exhaust valve 50 in the reciprocating pump 1 are located on the same side as seen from the piston 20.

[0034] The main shaft 60 is a member that can be rotated by power generated by a power source (not shown).

[0035] The connecting rod 70 is a member that connects the piston 20 and the main shaft 60. The connecting rod 70 is attached to both the piston 20 and the main shaft 60 by pins 72 in a manner that allows the angle to be changed. The connecting rod 70 is attached to the main shaft 60 at a position away from its rotation axis. Therefore, the rotational movement of the main shaft 60 can be used to reciprocate the piston 20.

[0036] Here, the operating cycle of the reciprocating pump 1 will be briefly described. First, let us assume that the piston 20 is at the farthest position from the intake port 12 and the exhaust port 14 among its reciprocating positions as the starting point (see FIG. 2(a)). When the main shaft 60 is rotated, power is transmitted to the piston 20 via the connecting rod 70, and the piston 20 moves toward the intake port 12 and the exhaust port 14 (see FIG. 2(b)). At this time, fluid present in the internal space of the cylinder 10 is pumped out of the cylinder 10 via the exhaust port 14 and the exhaust valve 50. Thereafter, the piston 20 reaches the position nearest to the intake port 12 and the exhaust port 14 among its reciprocating positions (see FIG. 2(c)). With continued rotation of the main shaft 60, the piston 20 moves away from the intake port 12 and the exhaust port 14 (see FIG. 2(d)). At this time, fluid present outside the cylinder 10 is sucked into the internal space of the cylinder 10 via the intake port 12 and the intake valve 40. Thereafter, the piston 20 reaches the same position as the starting point (see FIG. 2(a)), and the next cycle begins.

[0037] 2.Naturally derived resins and materials made from naturally derived resins 3A and 3B are diagrams illustrating a thermal conductivity test piece 100 constructed to measure the thermal conductivity of a naturally occurring resin (cashew-based resin) and an epoxy-based resin. Fig. 3A is a perspective view of the thermal conductivity test piece 100, and Fig. 3B is a side view of the thermal conductivity test piece 100. Figure 4 is a bar graph showing the thermal conductivity of a naturally derived resin (cashew-based resin) and an epoxy-based resin. The vertical axis of Figure 4 shows the temperature difference δ (equivalent to a thickness of 1 mm) (unit: K). Therefore, in Figure 4, the lower the bar, the better the thermal conductivity. Figure 5 is a set of photographs showing the test results for the heat resistance of a naturally derived resin (cashew-based resin) and an epoxy-based resin. Figure 5(a) is a photograph showing the test results for the epoxy-based resin (test results for CFRP-B, which will be described later), and Figure 5(b) is a photograph showing the test results for the cashew-based resin (test results for CFRP-A, which will be described later). In Figures 5(a) and 5(b), the samples on the left of the arrows are those that were not heated, and the samples on the right of the arrows are those that were heated. 6A to 6D are diagrams for explaining the method for manufacturing the piston ring 30 in the embodiment 1. Fig. 6A to Fig. 6D are diagrams showing the respective steps.

[0038] In this specification, "naturally derived resin" refers to a resin containing naturally derived materials such as sap and oils obtained from plants, and processed products thereof, or equivalents thereof, as the main component of the raw material. Note that, in this specification, "main component" refers to the component that occupies the largest proportion by weight of the components that make up a certain thing (excluding solvent components). For this reason, naturally derived resins do not contain various additives. Agent The naturally derived resin may contain additives such as those commonly used in resins. Furthermore, the naturally derived resin may contain a component derived from the mucus of red algae such as Agar as an additive, which can provide the effects of adjusting viscosity and improving heat resistance. It has also been found that if increased elasticity is desired, this can be achieved by adding a silicone-based material (for example, one used as a sealant) to the naturally derived resin.

[0039] Examples of plants from which naturally occurring materials can be extracted include cashew, lacquer, pistachio, macadamia, European hazel, almond, peach, apple, pear, cherry, strawberry, melon, watermelon, pecan, walnut, peanut, and ginkgo. Among the listed plants, lacquer sap can be used as a naturally occurring material or a raw material, while oils and fats extracted from seeds (including seed shells) or fruits of other plants can be used as naturally occurring materials or raw materials. When oils and fats extracted from the seeds or fruits of the above-listed plants are used as naturally occurring materials or raw materials, they can utilize waste products that are not generally used as foods, which is advantageous in terms of availability and cost. Examples of processing methods for converting sap and oils into processed products include heat treatment and chemical treatment to adjust the molecular structure of the compounds that make up the sap and oils.

[0040] The naturally derived resin used in embodiment 1 is preferably one that has better thermal conductivity and heat resistance than common petroleum-based synthetic resins, is easy to adjust viscosity for application by spraying, and can penetrate into the substrate of fiber-reinforced plastic. From the standpoint of processability, the naturally derived resin used in embodiment 1 is preferably one that has excellent moldability through room temperature curing (primary curing) and can be cured by baking (secondary curing).

[0041] When manufacturing the piston ring 30, there are cases where a naturally derived resin is applied to a substrate or where the naturally derived resin is cured into a predetermined shape. When applying the naturally derived resin to a thin film of the substrate or to the edge of the substrate, spray application using a spray gun, for example, can be used. Furthermore, when forming a thick film made of the naturally derived resin, when applying to a thick substrate, or when strongly imprinting the resin into the substrate, application using a brush or spatula, for example, can be used. In these work processes, thinner, for example, can be used to adjust the viscosity of the naturally derived resin before curing.

[0042] When a thick film (e.g., a film of 100 μm or more) made of a naturally-derived resin is formed using a spatula, the viscosity of the naturally-derived resin is increased before curing, the naturally-derived resin is filled into a mold using a spatula, and the naturally-derived resin is peeled off from the mold after primary curing. The mold can be easily formed, for example, by placing a rail material (guide material) on a flat plate. It is preferable to use a material (e.g., glass) from which the naturally-derived resin can be easily peeled off after curing as the mold.

[0043] When forming a thick film made of a naturally derived resin using a spatula as described above, a single application is often sufficient if the film thickness is less than 300 μm. On the other hand, if the film thickness is 300 μm or more, multiple applications (repeated applications) using primary curing can suppress surface distortion (curing distortion) that occurs when the naturally derived resin hardens.

[0044] In embodiment 1, in order to satisfy the above conditions, it is preferable that the naturally derived resin contains a cashew-based resin as a main component. In this specification, "cashew-based resin" refers to a resin containing, as a main raw material, cashew nut shell oil obtained from the seed shells of the cashew, an evergreen tree of the Anacardiaceae family.

[0045] Cashew nut shell oil obtained from cashews is an oil whose main components are phenolic compounds such as anacardic acid, cardanol, and cardol. For industrial use, cashew nut shell oil is obtained by decarboxylating anacardic acid to cardanol, with cardanol being the main component. Cashew-based resins can be obtained by adding necessary minor components and polymerization initiators to such cashew nut shell oil and polymerizing it.

[0046] In addition, resins made from modified molecular structures of components contained in cashew nut shell oil are also included in the cashew-based resins of this specification. For example, a resin (cashew-derived benzoxazine resin) made from cardanol, which is a benzoxazine-like molecule obtained by forming a six-membered ring containing nitrogen (amine moiety) so as to include a hydroxyl group and a part of an aromatic ring, can also be used as a cashew-based resin.

[0047] Although cashew-based resin itself is a known material, it has mainly been used as a component of paint, and research into its structural and thermal properties has not progressed. Research by the inventors of the present invention has revealed that cashew-based resin has heat resistance capable of withstanding temperatures exceeding 300°C, and is superior to general epoxy-based resins in thermal conductivity, breaking strength, rigidity, and light weight, as well as excellent adhesiveness and shock absorption properties.

[0048] Here, we will explain the test on the thermal conductivity of cashew-based resin. In this test, a thermal conductivity test piece 100 was constructed, which included a heat source 110 capable of maintaining a constant temperature, a first thermally conductive material 120 made of a copper plate, a test material 130 made of resin, and a second thermally conductive material 140 made of a copper plate (see FIG. 3). It can be said that the first thermally conductive material 120 and the second thermally conductive material 140 are bonded together by the test material 130. Two thermal conductivity test pieces 100 were prepared: one in which the test material 130 was made of cashew-based resin, and one (for comparison) in which the test material 130 was made of epoxy-based resin.

[0049] In the above test, "No. 53 Tou" manufactured by Cashew Corporation was used as the cashew resin. Also, "Cashew Dryer" manufactured by Cashew Corporation was used as the curing agent for the cashew resin.

[0050] In the above test, the epoxy resin used was "Bond Quick 5 (#16131)" manufactured by Konishi Co., Ltd. This epoxy resin is a two-component adhesive and is considered to have typical properties for epoxy resins.

[0051] The heat source 110 converts electrical power into heat and emits a constant amount of heat when supplied with a predetermined amount of electrical power. The heat emitted from the heat source 110 is transferred to the first thermally conductive material 120, the test material 130, and the second thermally conductive material 140. After a sufficient amount of time has passed since the start of the test, the temperatures at each location reach their saturation temperatures. Here, the saturation temperature of the portion of the first thermally conductive material 120 in contact with the test material 130 (the front portion of the test material) is defined as the high-side temperature, and the saturation temperature of the portion of the second thermally conductive material 140 in contact with the test material 130 (the rear portion of the test material) is defined as the low-side temperature. The temperature difference between the high-side and low-side temperatures obtained in the test can be divided by the thickness (in mm) of the test material 130 to calculate the temperature difference δ (equivalent to a 1 mm thickness), which is the temperature difference per mm of the test material 130. Temperature measurements were performed using a thermocouple from a Hioki E.E. Corporation Memory HiLogger LR8431.

[0052] As a result, the temperature difference δ (calculated at 1 mm thickness) in the cashew-based resin was approximately 30% of the temperature difference δ (calculated at 1 mm thickness) in the epoxy-based resin (see Figure 4). This confirmed that the cashew-based resin has significantly better thermal conductivity than the epoxy-based resin.

[0053] We also describe a test for the heat resistance of cashew-based resin. In this test, the test specimen was placed on the top cover of a convection kerosene heater (KSH-8BS-K5, manufactured by Sunpot Corporation) for 5 minutes (approximately 300°C, as confirmed by a non-contact radiation thermometer), and the condition during and after heating was observed. The test specimens used were CFRP-A, a carbon fiber reinforced plastic using cashew-based resin as the resin (matrix material), and CFRP-B, a carbon fiber reinforced plastic using epoxy-based resin as the resin. CFRP-A and CFRP-B were manufactured by impregnating a carbon fiber substrate with cashew-based resin or epoxy-based resin. The cashew-based resin and epoxy-based resin used in the above test were the same as those used in the thermal conductivity test.

[0054] As a result of the test, it was observed that CFRP-B emitted a thin layer of smoke during heating, and that some parts were carbonized and turned black after heating (see Figure 5(a). The area indicated by the dashed line is the carbonized part). On the other hand, for CFRP-A, no smoke was observed during heating, and although some parts turned dark brown after heating, no significant deterioration was observed (see Figure 5(b)). This confirmed that cashew-based resins have superior heat resistance compared to epoxy-based resins.

[0055] In addition, in embodiment 1, it is also preferable that the naturally derived resin contains a lacquer-based resin as a main component. In this specification, "lacquer-based resin" refers to a resin containing, as a main raw material component, the sap (lacquer) of a plant of the genus Urushi (particularly Urushi) of the family Anacardiaceae.

[0056] The components of lacquer vary depending on the place of origin, but one of the most notable is urushiol. Urushiol is a phenolic compound with a structure similar to cardanol and cardol, which are found in cashew nut shell oil. Lacquer resin can be obtained by polymerizing lacquer components such as urushiol.

[0057] Furthermore, resins made from modified molecular structures of components contained in lacquer are also included in the lacquer-based resins of this specification.

[0058] Lacquer resin is also a well-known material, but because it has mainly been used as a component of paint, little research has been done into its structural and thermal properties. Research by the inventors of the present invention has revealed that lacquer resin, like cashew resin, has heat resistance that can withstand temperatures exceeding 300°C, and is superior to general epoxy resins in thermal conductivity, breaking strength, rigidity, and lightness, as well as in adhesiveness and shock absorption.

[0059] In this specification, the term "material using a naturally derived resin" refers to a material containing a naturally derived resin. The material may also contain a synthetic resin in addition to a naturally derived resin (for example, a material that uses a mixture of a naturally derived resin and a synthetic resin as the resin). The material may also contain components other than resin.

[0060] In the first embodiment, the material using a naturally derived resin is preferably a naturally derived resin to which a silicone-based material has been added. The term "a naturally derived resin to which a silicone-based material has been added" can also refer to a naturally derived resin before hardening, which is then hardened by adding a silicone-based material. For example, a silicone-based sealant can be used as the silicone-based material. For example, KE3418-330, an ultra-heat-resistant sealant manufactured by Shin-Etsu Chemical Co., Ltd., is particularly suitable as the sealant.

[0061] In addition, in the first embodiment, the material using a naturally-derived resin is also preferably a naturally-derived resin to which carbon powder has been added. "A naturally-derived resin to which carbon powder has been added" can also be defined as a naturally-derived resin before hardening, which is then hardened by adding carbon powder. As the carbon powder, for example, bamboo charcoal powder (Bamboo Black, 10 microns) manufactured by Kannabe Hakutan Kobo Co., Ltd. is particularly suitable. Furthermore, the material using a naturally-derived resin may be a naturally-derived resin to which a silicone material and carbon powder have been added.

[0062] In addition, in embodiment 1, the material using a naturally derived resin is also preferably a carbon fiber reinforced plastic using a naturally derived resin as a matrix material (resin). In this case, the matrix material is preferably made of a resin obtained by adding a silicone-based material to a naturally derived resin, and is also preferably made of a resin obtained by adding carbon powder to a naturally derived resin. The matrix material may also be made of a resin obtained by adding a silicone-based material and carbon powder to a naturally derived resin.

[0063] 3. Manufacturing method of piston ring 30 Here, an example of a method for manufacturing the piston ring 30 will be described. First, an original plate 30a, which is a precursor of the piston ring 30, is prepared and set between the dies 200 (see FIG. 6(a)). The original plate 30a is made of a material using a naturally occurring resin. The original plate 30a can be manufactured by any method of forming a material using a naturally occurring resin into a plate shape. The dies 200 include an upper die 210, a lower die 220, and a cutting pin 230. It is not particularly limited which of the upper die 210 and the lower die 220 is movable and which is fixed. It is also preferable to heat the upper die 210 and the lower die 220 to 100°C to 150°C.

[0064] Next, the original plate 30a is sandwiched between an upper mold 210 and a lower mold 220 to form the basic shape (see FIG. 6(b)). After that, the cutting pin 230 is moved to cut off the unnecessary portion (see FIG. 6(c)). In this way, the piston ring 30 can be manufactured (see FIG. 6(d)).

[0065] The method for manufacturing the piston ring 30 is not limited to the above method, and it can also be manufactured by injection molding or the like.

[0066] Furthermore, when the material using a naturally occurring resin is a carbon fiber reinforced plastic using a naturally occurring resin as a matrix material, the piston ring 30 can also be manufactured by a method including, for example, a substrate preparation step, an impregnation step, and a curing step.

[0067] The substrate preparation process is a process for preparing a carbon fiber reinforced plastic substrate. The impregnation process is a process for impregnating the substrate with a resin containing a naturally occurring resin. The substrate preparation process and the impregnation process are basically the same as known carbon fiber reinforced plastic manufacturing methods, and therefore detailed explanations are omitted. Known carbon fiber reinforced plastic manufacturing methods include autoclave molding, resin transfer molding (RTM) molding, vacuum-assisted resin transfer molding (VaRTM) molding, and sheet molding compound (SMC) molding. Any method can be selected depending on the shape of the piston ring 30 to be manufactured. Alternatively, the viscosity of the resin containing a naturally occurring resin may be adjusted by adding a solvent or the like, and then spray-applied to the substrate. The above manufacturing methods may also be combined as appropriate. Depending on the selected method, the substrate is molded into a shape corresponding to the piston ring 30 to be manufactured at some point before the curing process.

[0068] The curing process is a process of curing the resin by baking. In this specification, "baking" refers to a heat treatment performed in the final stage of molding. A specific baking method can be selected according to the substrate preparation process, the impregnation process, the substrate molding method, etc., and examples of the baking method include heating the mold used in molding and direct heating using an oven or heater.

[0069] 4. Effect of reciprocating pump 1 In the reciprocating pump 1 according to the first embodiment, at least the portion of the piston ring 30 that contacts the inner wall of the cylinder 10 is made of a material using a naturally-derived resin. Therefore, by using a naturally-derived resin that has excellent thermal properties and breaking strength, the reciprocating pump 1 according to the first embodiment is a reciprocating pump that can improve the pumping amount and suction amount per hour by increasing the reciprocating motion of the piston compared to conventional reciprocating pumps.

[0070] Furthermore, according to the reciprocating pump 1 of the first embodiment, the piston ring 30 is entirely made of a material using a naturally occurring resin, and therefore the thermal properties and strength of the piston ring 30 as a whole can be improved.

[0071] Furthermore, according to the reciprocating pump 1 of embodiment 1, when the naturally derived resin contains cashew-based resin as a main component, the cashew-based resin has excellent heat resistance, thermal conductivity, rigidity, light weight, adhesiveness, and shock absorption properties, and therefore, it is possible to improve the thermal properties and strength of the piston ring 30.

[0072] Furthermore, according to the reciprocating pump 1 of embodiment 1, when the naturally derived resin contains a lacquer-based resin as a main component, the lacquer-based resin is used, which has excellent heat resistance, thermal conductivity, rigidity, light weight, adhesiveness, and impact absorption properties, and therefore it is possible to improve the thermal properties and strength of the piston ring 30.

[0073] Furthermore, according to the reciprocating pump 1 of embodiment 1, when the material using the naturally occurring resin is a naturally occurring resin to which a silicone-based material has been added, it is possible to increase the flexibility of the piston ring 30 without impairing the heat resistance.

[0074] Furthermore, according to the reciprocating pump 1 of embodiment 1, when the material using the naturally occurring resin is a naturally occurring resin to which carbon powder has been added, it is possible to reduce the frictional resistance between the piston ring 30 and the inner wall of the cylinder 10 without impairing the heat resistance of the piston ring 30.

[0075] Furthermore, according to the reciprocating pump 1 of embodiment 1, when the material using the naturally occurring resin is a carbon fiber reinforced plastic using the naturally occurring resin as a matrix material, it is possible to make the piston ring 30 excellent in heat resistance, flexibility, and rigidity.

[0076] Furthermore, according to the reciprocating pump 1 of embodiment 1, when the matrix material is made of a resin in which a silicone-based material is added to a naturally occurring resin, it is possible to increase the flexibility of the piston ring 30 without impairing the heat resistance.

[0077] Furthermore, according to the reciprocating pump 1 of embodiment 1, when the matrix material is made of a resin in which carbon powder is added to a naturally occurring resin, it is possible to reduce the frictional resistance between the piston ring 30 and the inner wall of the cylinder 10 without impairing the heat resistance of the piston ring 30.

[0078] [Embodiment 2] Fig. 7 is a diagram for explaining a reciprocating pump 2 according to embodiment 2. Fig. 7(a) is a cross-sectional view of the reciprocating pump 2, Fig. 7(b) is a plan view of a piston ring 32, and Fig. 7(c) is a cross-sectional view taken along B2-B2 in Fig. 7(b).

[0079] The reciprocating pump 2 according to the second embodiment basically has the same configuration as the reciprocating pump according to the first embodiment, but the piston ring is different from that of the reciprocating pump according to the first embodiment. In the piston ring 32 according to the second embodiment, an outer circumferential portion 32a including the outer periphery that contacts the inner wall of the cylinder 10 and an inner circumferential portion 32b therein are made of different materials (see FIG. 7).

[0080] The outer peripheral portion 32a is made of a material using a naturally occurring resin. On the other hand, the material of the inner peripheral portion 32b is not particularly limited. However, from the viewpoint of improving the thermal characteristics and breaking strength of the entire piston ring 32, it is preferable that the inner peripheral portion 32b is also made of a material using a naturally occurring resin.

[0081] For example, the outer peripheral portion 32a may be made of a material in which at least one of a silicone-based material and carbon powder is added to a naturally occurring resin, and the inner peripheral portion 32b may be made of a carbon fiber reinforced plastic using a naturally occurring resin as a matrix material. The carbon fiber reinforced plastic of the inner peripheral portion 32b is preferably made of at least one of a silicone-based material and carbon powder added. Furthermore, the combination of the outer peripheral portion 32a and the inner peripheral portion 32b may be other than those described above.

[0082] Although the reciprocating pump 2 according to the second embodiment has a piston ring different from that of the reciprocating pump 1 according to the first embodiment, at least the portion of the piston ring 32 that contacts the inner wall of the cylinder 10 is made of a material using a naturally derived resin. Therefore, like the reciprocating pump 1 according to the first embodiment, the reciprocating pump 2 according to the second embodiment uses a naturally derived resin that has excellent thermal properties and breaking strength, and is therefore a reciprocating pump that can improve the pumping amount and suction amount per hour by increasing the reciprocating motion of the piston compared to conventional reciprocating pumps.

[0083] Furthermore, in the reciprocating pump 2 according to the second embodiment, the outer circumferential portion 32a and the inner circumferential portion 32b are made of different materials, and therefore, by using materials suitable for each position, it is possible to change the characteristics of the outer circumferential portion 32a and the inner circumferential portion 32b. For example, it is conceivable to use a material that is excellent in compatibility with the cylinder 10, gas-tightness, and low resistance for the outer circumferential portion 32a, and a material that is excellent in strength and hardness for the inner circumferential portion 32b.

[0084] Although the present invention has been described based on the above-mentioned embodiments, the present invention is not limited to the above-mentioned embodiments. The present invention can be embodied in various forms without departing from the spirit of the present invention, and for example, the following modifications are also possible.

[0085] (1) The position, size, shape, etc. of each component described in each of the above embodiments are merely examples and may be changed within the scope of the present invention without impairing the effects of the present invention. Furthermore, the drawings showing the structure of objects used to explain each of the above embodiments are schematic diagrams and may not accurately depict the position, size, etc. of each component.

[0086] (2) While the reciprocating pumps 1 and 2 according to the above embodiments include components (main shaft 60 and connecting rod 70) for reciprocating the piston 20, the present invention is not limited to this. The reciprocating pump of the present invention may not include all or some of the components for reciprocating the cylinder. In this case, the reciprocating pump is used by connecting a device for reciprocating the cylinder. Furthermore, the reciprocating pump of the present invention may include components for reciprocating the cylinder, including a power source.

[0087] (3) The reciprocating pumps 1 and 2 according to the above embodiments are reciprocating pumps that operate by converting rotation into reciprocating motion, but the present invention is not limited to this. The reciprocating pump of the present invention may use a power source that generates linear power (reciprocating motion).

[0088] (4) In the reciprocating pumps 1 and 2 according to the above embodiments, the intake port 12 and the exhaust port 14 (and hence the intake valve 40 and the exhaust valve 50) are located on the same side as viewed from the piston 20, but the present invention is not limited to this. In the reciprocating pump of the present invention, the intake port and the exhaust port may be located on different sides as viewed from the piston. In this case, holes provided in the piston rings, such as the through-hole 31 in the piston rings 30 and 32, can be used as a passage for fluid flowing from the intake port to the exhaust port.

[0089] Fig. 8 is a diagram illustrating a reciprocating pump 3 according to a modified example. The reciprocating pump 3 is an example of the "reciprocating pump in which the intake port and the exhaust port are located on different sides as viewed from the piston." As shown in Fig. 8, the reciprocating pump 3 includes a cylinder 10a, a piston 20a, a piston ring 30, a piston ring fixing member 36a, a piston valve 39, an exhaust valve 50, a main shaft 60, and a connecting rod 70.

[0090] In addition to the piston 20a, the cylinder 10a also contains a main shaft 60 and a connecting rod 70. The intake port 12a and the exhaust port 14 of the cylinder 10a are located on different sides of the piston 20a (opposite sides of the piston 20a). The piston 20a is formed with a vent hole 22, and the piston ring fixing member 36a is formed with a vent hole 38. A piston valve 39 is disposed at the end of the vent hole 38 on the exhaust port 14 side, and determines the direction of fluid movement inside the cylinder 10a (the direction from the intake port 12a toward the exhaust port 14; upward in FIG. 8).

[0091] 9 is a diagram illustrating a reciprocating pump 4 according to a modified example. The reciprocating pump 4 is also an example of the "reciprocating pump in which the intake port and the exhaust port are located on different sides as viewed from the piston." As shown in FIG. 9, the reciprocating pump 4 includes a cylinder 10b, a piston 20b, a piston ring 30, a piston ring fixing member 36b, a piston valve 23, an intake valve 40, a main shaft 60, and a connecting rod 70.

[0092] In addition to the piston 20b, the cylinder 10b also contains a main shaft 60 and a connecting rod 70. The intake port 12 and the exhaust port 14b of the cylinder 10b are located on different sides of the piston 20b (opposite sides of the piston 20b). The piston 20b is formed with a vent hole 22, and the piston ring fixing member 36b is formed with a vent hole 38. A piston valve 23 is disposed at the end of the vent hole 38 on the piston 20b side, and determines the direction of fluid movement inside the cylinder 10b (the direction from the intake port 12 toward the exhaust port 14a; downward in FIG. 9).

[0093] The reciprocating pump of the present invention can also be configured as the above-described reciprocating pumps 3 and 4. The above-described reciprocating pump 3 can be used as a compressor (pumping device) or a part thereof, and the reciprocating pump 4 can be used as a suction device (vacuum pump) or a part thereof. [Explanation of symbols]

[0094] 1,2,3,4...Reciprocating pump, 10,10a,10b...Cylinder, 12,12a...Intake port, 14,14b...Exhaust port, 20,20a,20b...Piston, 22,38...Ventilation hole, 23,39...Piston valve, 30,32...Piston ring, 30a...Base plate, 31...Through hole, 32a...Outer periphery, 32b...Inner periphery, 36,36a,36b...Piston ring fixing member, 40...Intake valve, 50...Exhaust valve, 60...Main shaft, 70...Connecting rod, 72...Pin, 200...Mold, 210...Upper mold, 220...Lower mold, 230...Cutting pin, A...Central axis

Claims

1. A reciprocating pump including a cylindrical cylinder, a piston capable of reciprocating within the cylinder, and a piston ring fixed to the piston and having an outer periphery in contact with an inner wall of the cylinder, 10. A reciprocating pump, wherein at least a portion of the piston ring that contacts the inner wall of the cylinder is made of a material using a naturally occurring resin.

2. 2. The reciprocating pump according to claim 1, wherein the piston ring is entirely made of a material using the naturally occurring resin.

3. 2. The reciprocating pump according to claim 1, wherein the naturally derived resin contains cashew-based resin as a main component.

4. 2. The reciprocating pump according to claim 1, wherein the naturally occurring resin contains a lacquer-based resin as a main component.

5. 2. The reciprocating pump according to claim 1, wherein the material using the naturally occurring resin is a mixture of the naturally occurring resin and a silicone-based material.

6. 2. The reciprocating pump according to claim 1, wherein the material using the naturally occurring resin is the naturally occurring resin to which carbon powder has been added.

7. 2. The reciprocating pump according to claim 1, wherein the material using the naturally occurring resin is a carbon fiber reinforced plastic using the naturally occurring resin as a matrix material.

8. 8. The reciprocating pump according to claim 7, wherein the matrix material is made of a resin containing the naturally occurring resin and a silicone-based material.

9. 8. The reciprocating pump according to claim 7, wherein the matrix material is made of the naturally occurring resin to which carbon powder has been added.

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