Pressure-resistant explosion-proof valve actuator and method for assembling a pressure-resistant explosion-proof valve actuator

Abstract

[Problem] To provide a compact and lightweight pressure-resistant explosion-proof valve actuator which can be easily retrofitted to valves installed in piping, allows for motorization of the valve, and can be used in an atmosphere where explosive gases are present, as well as a method for assembling a pressure-resistant explosion-proof valve actuator. [Solution] A valve actuator 1 has an explosion-proof housing 10 and a valve attachment part 4. The explosion-proof housing 10 has: a main frame 11 that serves as a main body accommodating an actuator drive part 3; and a lid part 100 that closes the upper part of the main frame 11 with the actuator drive part accommodated therein. A plurality of side-surface lightening sections 15 are formed in the outer peripheral surface of each of four side panels 13a, 13b, 13c, 13d of the main frame 11. Each side-surface lightening section 15 has a notch 150 formed at the bottom, and is shaped so as not to reach the upper edge of each side panel.

Description

[Technical Field]

[0001] The present invention relates to a flameproof valve actuator and a method for assembling a flameproof valve actuator. More specifically, the present invention relates to a small and lightweight flameproof valve actuator that can be easily retrofitted to a valve provided in a pipe, can motorize the valve, can be used in an atmosphere where explosive gas exists, and a method for assembling the flameproof valve actuator. [Background Art]

[0002] Conventionally, actuators have been widely used as drive sources that convert energy such as electricity or hydraulic pressure into mechanical motion to drive equipment.

[0003] Further, although there are various types of actuators depending on the type of operating principle and application, valve actuators that are connected to a valve and open / close the valve by the rotational force of a motor have been proposed.

[0004] Further, in piping of facilities such as chemical plants, power plants, and ships, a large number of valves are used to control the fluid flowing through the piping. In order to save the labor of opening and closing a huge number of manual valves, there is a strong demand for motorizing manual valves provided in piping using valve actuators.

[0005] The need for motorizing such manual valves is not limited to cases where new valves are installed, and it is thought that this need will increase in the future for facilities that are already in operation during maintenance and refurbishment.

[0006] On the other hand, in an atmosphere where explosive gas exists, there is a risk that explosive gas may ignite and cause an explosion due to malfunction of an electrically driven actuator, so an explosion-proof structure is required. For example, the adoption of a flameproof structure, which is a type of explosion-proof structure, is considered.

[0007] Furthermore, a pressure-resistant explosion-proof structure means a structure in which, even if explosive gas enters a container enclosing electrical equipment and explodes inside, the container can withstand the explosion pressure and there is no risk of the explosive gas igniting outside.

[0008] In conventional actuators with pressure-resistant explosion-proof structures, a pressure-resistant explosion-proof structure specifically designed for the device using the actuator is constructed (see, for example, Patent Document 1).

[0009] Furthermore, in pressure-resistant explosion-proof structures, the container covering actuators and drive units is required to have sufficient strength to withstand the maximum explosion pressure when explosive gases that have entered the container explode. Therefore, the flange joints provided on the outer edges of the container body and lid, which make up the container, have a deep depth, and a structure is adopted that gives the container walls a thick wall thickness. In addition, the container is made of heavy materials such as iron. [Prior art documents] [Patent Documents]

[0010] [Patent Document 1] Specification of Japanese Patent No. 7420458 [Overview of the project] [Problems that the invention aims to solve]

[0011] However, these conventional actuators, which have a pressure-resistant explosion-proof structure specifically designed for the devices they are intended for installation on, are not designed to be retrofitted to existing devices; it was necessary to replace the entire existing device. In other words, they were difficult to apply to cases where manual valves already installed in piping, etc., could be utilized while later electrifying the system.

[0012] Furthermore, in pressure-resistant explosion-proof containers, the flange joints have a deep depth, the container walls are made of thick material, and they are formed from heavy materials such as iron, which inevitably makes the containers larger and heavier.

[0013] For example, inside ships and chemical plants, multiple pipes are densely arranged in a limited, narrow space, resulting in areas where the pipes are very close together. In such areas, the short distance between adjacent pipes makes it difficult to secure enough space to install a pressure-resistant explosion-proof valve actuator, which requires a larger container.

[0014] Furthermore, in order to apply a heavy, pressure-resistant explosion-proof valve actuator to a valve on a pipe suspended in mid-air, a large and robust support structure must be provided around the pipe to prevent deformation or damage to the pipe due to the load of that weight. However, in the narrow space where the pipes are densely arranged, it is not possible to create such a support structure, and therefore it is not possible to provide a pressure-resistant explosion-proof structure.

[0015] The present invention was conceived in view of the above points, and aims to provide a compact and lightweight pressure-resistant explosion-proof valve actuator and a method for assembling a pressure-resistant explosion-proof valve actuator that can be easily retrofitted to a valve installed in piping, allows for the motorization of the valve, can be used in an atmosphere containing explosive gases, etc. [Means for solving the problem]

[0016] To achieve the above objective, the explosion-proof valve actuator of the present invention comprises an electrically driven actuator drive unit, a bracket attached to the actuator drive unit and configured to be rotatable by the driving force of the actuator drive unit, and which engages with the handle of a predetermined valve provided in piping to open and close the predetermined valve, an explosion-proof housing made of aluminum and having a pressure-resistant explosion-proof structure that covers the actuator drive unit and the bracket unit, and a valve mounting part attached to the predetermined valve and supporting the explosion-proof housing above the handle, wherein the explosion-proof housing has a housing body capable of housing the actuator drive unit inside, and a housing lid attached to the top surface of the housing body when the actuator drive unit is housed inside the housing body, and a plurality of side cutouts are formed on the side surface of the housing body, which are thinner than the side surface and have a shape in which only the bottom end is cut out, and the inner bottom of the housing body is configured to have a predetermined thickness.

[0017] Here, an electrically driven actuator drive unit and a bracket unit attached to the actuator drive unit, configured to be rotatable by the driving force of the actuator drive unit, and fitted with the handle of a predetermined valve provided in the piping to open and close the predetermined valve, make it possible to motorize the opening and closing of a predetermined valve via the driving force of the actuator drive unit.

[0018] Furthermore, because the explosion-proof housing has a pressure-resistant explosion-proof structure that covers at least a portion of the actuator drive unit and the bracket unit, it becomes possible to operate the electrically driven actuator drive unit in an explosive atmosphere where explosive gases are present outside. In other words, even if an ignition source is generated due to a malfunction in the actuator drive unit and an explosion occurs inside the explosion-proof housing, the explosion-proof housing can withstand the explosion pressure and prevent the external explosive gases from igniting.

[0019] Furthermore, because the explosion-proof housing is made of aluminum, it is easier to reduce the weight of the explosion-proof housing compared to a design made of a denser material such as iron.

[0020] Furthermore, by attaching the valve mounting portion to a predetermined valve and supporting the explosion-proof housing above the handle, it becomes possible to attach the actuator drive unit, bracket portion, and explosion-proof housing to the predetermined valve via the valve mounting portion.

[0021] Furthermore, the explosion-proof housing has a housing body capable of housing the actuator drive unit inside, and a housing lid that is attached to the top surface of the housing body when the actuator drive unit is housed inside the housing body, thereby creating a structure in which the actuator drive unit is covered by the housing body and the housing lid.

[0022] Furthermore, by forming multiple side cutouts on the sides of the housing body, which are thinner than the sides themselves, it is possible to maintain a certain thickness on the sides of the housing body, thereby ensuring the strength necessary for a pressure-resistant explosion-proof structure, while reducing the weight of the housing body. In other words, by reducing the overall weight of the explosion-proof housing, the load on the piping where the designated valve is installed can be reduced.

[0023] Further, since the plurality of side lightening portions are formed on the side surface of the housing main body, have a thickness smaller than that of the side surface, and have a shape in which only the end portion on the bottom side is notched, the number of man-hours in the manufacturing process is reduced, which facilitates the manufacture of the housing main body. That is, for example, the housing main body can be formed by casting in which two molds are matched with each other. Specifically, since the shape of the side lightening portion is a shape in which only the end portion on the bottom side is notched with respect to the side surface, the uneven shape can be formed by matching a first mold that models a portion corresponding to the upper side of the housing main body and a second mold that models a portion corresponding to the bottom side of the housing main body. Therefore, the housing main body can be manufactured by a manufacturing procedure in which two molds are matched for casting, which requires a relatively small number of molds and a relatively small number of mold matching processes. As a result, the manufacturing labor can be reduced and the manufacturing cost can be lowered.

[0024] Further, on the side surface of the housing main body, the plurality of side lightening portions each having a thickness smaller than that of the side surface and a shape in which only the end portion on the bottom side is notched are formed, and the inner bottom portion of the housing main body has a predetermined thickness, whereby the strength required for the pressure-resistant and explosion-proof structure can be ensured even on the bottom side of the housing main body. That is, in the side lightening portion formed on the side surface of the housing main body, since the end portion on the bottom side of the side surface is notched, the strength on the bottom side is reduced when viewed only from the side surface. However, inside the housing main body, the inner bottom portion has a predetermined thickness, so the strength of the thin-walled portion on the bottom side of the side surface can be covered by the thick portion of the inner bottom portion. As a result, the entire bottom side of the housing main body can be provided with the strength required for the pressure-resistant and explosion-proof structure.

[0025] Further, in a case where a cylindrical projecting portion is provided on the bottom surface of the housing main body, the cylindrical projecting portion projecting downward from the bottom surface and having a through hole formed therein that communicates with the inside of the housing main body, a bracket attached to an actuator drive portion can be inserted through the through hole of the projecting portion, and the lower end of the bracket portion can be arranged below the housing main body. Further, a valve attachment portion can be attached to the projecting portion, and a structure for supporting the explosion-proof housing by the valve attachment portion can be constructed.

[0026] Further, in the case where a plurality of bottom surface lightening portions formed to have a smaller thickness than the bottom surface are formed on the bottom surface of the housing body around the protrusion, a certain thickness can be provided to the bottom surface of the housing body, and the weight of the housing body can be further reduced while ensuring the strength required for the pressure-resistant explosion-proof structure. That is, the structure is lightened not only on the side surface of the housing body but also on the bottom surface, so that the overall weight of the explosion-proof housing can be further reduced, and the load applied to the pipe provided with the predetermined valve can be reduced.

[0027] Further, when the total weight of the actuator driving portion, the bracket portion and the explosion-proof housing is 10 kg or less, the overall weight composed of the actuator driving portion, the bracket portion and the explosion-proof housing can be reduced, and the load applied to the pipe provided with the predetermined valve can be further reduced. That is, for example, it is assumed that the weight applied when an operator puts his / her body weight on the valve or the pipe to open or close the valve is about 10 to 20 kg at most. Therefore, by setting the total weight composed of the actuator driving portion, the bracket portion and the explosion-proof housing to 10 kg or less, deformation and damage of the pipe can be sufficiently suppressed.

[0028] Further, in the case where the side surface lightening portion is formed in a shape whose lateral width gradually decreases from the bottom side toward the upper side of the side surface of the housing body, a region having a smaller thickness than the side surface, that is, a lightened region formed by removing material can be widely provided on the bottom side of the side surface. In addition, since the inner bottom surface of the housing body has a predetermined thickness, the strength required for the explosion-proof structure can be ensured even if a large lightened region formed by removing material is provided on the bottom side of the side surface.

[0029] Furthermore, if multiple side cutouts are formed at regular intervals on at least one side of the housing body, the side cutouts can be efficiently provided across the entire area of ​​one side, making it easier to further reduce the weight of the housing body. In addition, since each side has an even distribution of thicker and thinner sections, resulting in a well-balanced shape in terms of thickness differences, it becomes easier to maintain the overall pressure resistance of the housing body.

[0030] Furthermore, if the explosion-proof housing has sufficient strength to withstand an explosion pressure of 0.811 MPa or less, it will be considered to have sufficient strength for a pressure-resistant explosion-proof structure. The value of 0.811 MPa refers to the maximum explosion pressure generated when a mixture of hydrogen and air, with a composition of 30% hydrogen and 70% air, explodes. In other words, the explosion-proof housing will have the necessary strength for a pressure-resistant explosion-proof structure against an explosion of a hydrogen and oxygen mixture.

[0031] Furthermore, if the bottom surface of the housing body has ribs that separate adjacent bottom surface cutouts and are formed radially around a protruding part, it becomes easier to improve the pressure resistance of the bottom surface of the housing body. Also, the bottom surface of the housing body will have evenly distributed thicker and thinner sections, resulting in a well-balanced shape in terms of thickness differences, which makes it easier to maintain the overall pressure resistance of the housing body.

[0032] Furthermore, the actuator drive unit includes a motor that serves as a drive source with a rotating shaft, a first pulley attached to the rotating shaft, a second pulley paired with the first pulley, a belt stretched between the first and second pulleys, a worm gear to which the second pulley is attached, and a worm gear reducer that is arranged perpendicular to the worm gear and transmits power through meshing with the worm gear. When the bracket is attached to the worm gear reducer, torque is output from the motor's output, allowing the bracket to open and close the valve. In other words, power can be supplied to the motor to motorize the valve.

[0033] Furthermore, when the bracket is fitted to the handle of a designated valve and attached to the actuator drive unit, the torque obtained from the motor and worm gear reducer inside the housing case can be directly transmitted to the valve handle. This also makes it easier to miniaturize the entire actuator.

[0034] Furthermore, by using a first pulley attached to the motor's rotating shaft, a second pulley paired with the first pulley and having a larger diameter than the first pulley, and a belt stretched between the first and second pulleys, the rotational speed of the second pulley can be made smaller than that of the first pulley, thereby transmitting the motor's output to the worm gear reducer. In other words, a reduction ratio can be obtained not only from the worm gear reducer, but also from the ratio of the diameters of the first and second pulleys, making it possible to output high torque from the motor's rotational force. As a result, a motor with low output and small size can be used as the drive source, and the entire actuator can be made smaller.

[0035] Furthermore, if the actuator drive unit has a housing case, the components that make up the actuator drive unit, such as the motor, can be housed in the housing case to form a single structure. In addition, by housing this housing case in an explosion-proof housing, not only can the actuator drive unit be placed, but the internal space of the explosion-proof housing can be filled with the housing case, reducing the space through which explosive gases can enter.

[0036] Furthermore, in order to achieve the above objectives, the assembly method for the pressure-resistant explosion-proof valve actuator of the present invention comprises a casting step of casting a housing body, which is a box-shaped body capable of housing an electrically driven actuator drive unit inside, and which has a plurality of side cutouts formed on its side surface, the cutouts being smaller in thickness than the side surface and cut out only at the bottom end, by matching a first mold and a second mold and pouring aluminum into it; a housing step of housing the actuator drive unit in the housing body cast in the casting step and attaching a lid to the top surface of the housing body to construct an explosion-proof housing having a pressure-resistant explosion-proof structure; and an arrangement step of arranging a bracket that rotates with the driving force of the actuator drive unit on the handle of a predetermined valve provided in a pipe, and arranging the explosion-proof housing above the handle via a valve mounting portion.

[0037] Here, by forming multiple side cutouts on the side of the housing body, which are thinner than the side and have a shape where only the bottom end is cut out, it is possible to maintain a certain thickness on the side of the housing body, thereby ensuring the strength necessary for a pressure-resistant explosion-proof structure, while reducing the weight of the housing body. In other words, by reducing the weight of the entire explosion-proof housing, the load on the piping in which the predetermined valve is installed can be reduced.

[0038] Furthermore, in the casting process, the housing body, which has multiple side cutouts formed on its sides that are thinner than the sides and have a shape in which only the bottom end is cut out, can be manufactured with fewer steps by casting aluminum by joining a first mold and a second mold. In other words, the housing body can be formed by casting by joining two molds. Specifically, since the shape of the side cutouts is such that only the bottom end of the side is cut out, it is an uneven shape that can be formed by joining two molds: a first mold that represents the upper part of the housing body and a second mold that represents the bottom part of the housing body. Therefore, it is possible to manufacture the housing body using a manufacturing procedure that requires relatively few molds and fewer mold-joining steps, by casting by joining two molds. As a result, the effort required for manufacturing can be reduced, and manufacturing costs can be lowered.

[0039] Furthermore, in the housing process, the actuator drive unit is housed in the housing body cast in the casting process, and a lid is attached to the top surface of the housing body to construct an explosion-proof housing with a pressure-resistant explosion-proof structure. This allows the actuator drive unit to be covered by the housing body and the housing lid, and the actuator drive unit to be positioned inside the explosion-proof housing.

[0040] Furthermore, during the placement process, a bracket that rotates using the driving force of the actuator drive unit is placed on the handle of a predetermined valve installed in the piping, and an explosion-proof housing is placed above the handle via the valve mounting portion. In this way, the actuator drive unit, bracket unit, and explosion-proof housing are attached to the predetermined valve, making the valve motorized.

[0041] Furthermore, if the designated valve is an existing valve installed in the piping, an actuator drive unit covered with an explosion-proof housing can be attached to the existing valve, allowing the existing valve to be retrofitted and motorized. [Effects of the Invention]

[0042] The pressure-resistant explosion-proof valve actuator according to the present invention can be easily retrofitted to valves installed in piping, allows for the motorization of the valve, can be used in atmospheres containing explosive gases, and is compact and lightweight. Furthermore, the method for assembling the pressure-resistant explosion-proof valve actuator according to the present invention allows for easy retrofitting to valves installed in piping, enables the motorization of the valve, can be used in atmospheres where explosive gases are present, and allows for the assembly of a small and lightweight pressure-resistant explosion-proof valve actuator. [Brief explanation of the drawing]

[0043] [Figure 1] This is a schematic diagram showing a valve to which a valve actuator, which is an example of a valve actuator according to the present invention, is attached. [Figure 2] This is a schematic perspective view showing the overall structure of the explosion-proof housing and valve mounting section. [Figure 3] This is a schematic perspective view showing the gear case of the actuator drive unit. [Figure 4] (a) is a schematic perspective view showing the main frame of the explosion-proof housing, and (b) and (c) are schematic perspective views showing the lid of the explosion-proof housing. [Figure 5] (a) to (d) are schematic diagrams showing the four side panels of the main frame. [Figure 6] This is a schematic diagram showing the bottom of the mainframe. [Figure 7] This diagram shows the internal structure of the gear case as viewed from above, with (a) being a schematic perspective view and (b) being a schematic plan view. [Figure 8] This is a schematic cross-sectional view showing the bracket portion and its surrounding structure. [Figure 9] This is a schematic perspective view showing the positional relationship between the bracket and the valve mounting section, as well as the structure of the valve mounting section. [Figure 10]This is a schematic process diagram showing the process of attaching a valve actuator to a manual valve. (a) is a schematic diagram showing the structure of the manual valve to be fitted, and (b) and (c) are schematic diagrams showing the attachment of the stand. [Figure 11] Following Figure 10, the following is a schematic process diagram showing the process of attaching the valve actuator to a manual valve, where (a) is a schematic diagram showing the attachment of the adapter and mounting plate to the protruding part, (b) is a schematic diagram showing the state in which the position of the explosion-proof housing and the position of the stand are aligned, and (c) is a schematic diagram showing the state in which the attachment of the explosion-proof housing to the valve is completed. [Figure 12] (a) is a schematic diagram showing a valve actuator having an explosion-proof housing with honeycomb-shaped cutouts formed on the sides, and (b) is a schematic diagram showing a valve actuator having an explosion-proof housing with a closed rectangular cutout and a rectangular cutout with a cutout on the bottom side formed on the sides. [Modes for carrying out the invention]

[0044] The embodiments of the present invention will be described below to facilitate understanding of the present invention.

[0045] The inventors conducted the following studies in order to construct a compact and lightweight explosion-proof valve actuator with a pressure-resistant structure.

[0046] First, the inventors manufactured valve actuator S1 shown in Figure 12(a) and valve actuator S2 shown in Figure 12(b) as pressure-resistant explosion-proof valve actuators. Valve actuator S1 and valve actuator S2 differ from valve actuator 1, which will be described later, only in the shape of the side surface of the explosion-proof housing; all other components are the same.

[0047] Here, the valve actuator S1 has an explosion-proof housing 110, and the actuator drive unit (not shown) is housed inside the explosion-proof housing 110, creating a pressure-resistant explosion-proof structure (see Figure 12(a)).

[0048] Furthermore, the explosion-proof housing 110 has a box-shaped main frame 111 that serves as the body for housing the actuator drive unit, and a lid 112 that closes the top of the main frame 111 when the actuator drive unit is housed inside. The explosion-proof housing is made of aluminum.

[0049] Furthermore, honeycomb-shaped cutouts 114 are evenly formed on the outer circumferential surface of the four sides 113 of the main frame 111. The cutouts 114 are formed as recesses that do not penetrate the side 113, along the thickness direction of the side 113.

[0050] This weight-reducing section 114 is a part of the main frame 111 where the weight of the main frame 111 is reduced by removing material from the side surface 113, within a range that can ensure the pressure resistance strength of the explosion-proof housing 110 as a pressure-resistant explosion-proof structure. Furthermore, the solid outer edge portion forming the weight-reducing section 114 acts as a rib, and even though the side surface 113 is reduced in thickness and a region with a small thickness is formed, the pressure resistance strength of the side surface 113 can be maintained.

[0051] Although not shown in the diagram, the bottom surface of the main frame 111 has multiple recessed cutouts that do not penetrate the bottom surface, running along the thickness direction of the bottom surface. These cutouts on the bottom surface also contribute to reducing the weight of the main frame 111.

[0052] In this valve actuator S1, the explosion-proof housing 110 has pressure resistance that can withstand explosion pressures of 0.811 MPa or less, which is the maximum explosion pressure inside. In addition, the overall weight of the explosion-proof housing 110 has been reduced, so even when the valve actuator S1 is attached to the valve 2 installed on the piping, the weight is sufficient to prevent deformation or damage to the piping.

[0053] Furthermore, the valve actuator S2 has an explosion-proof housing 120, and the actuator drive unit (not shown) is housed inside the explosion-proof housing 120, creating a pressure-resistant explosion-proof structure (see Figure 12(b)).

[0054] The difference between valve actuator S2 and valve actuator S1 lies in the shape of the four sides 123 of the main frame 121 of the explosion-proof housing 120; other structural features are the same.

[0055] Furthermore, the explosion-proof housing 120 has a box-shaped main frame 121 and a lid 122. The explosion-proof housing is also made of aluminum.

[0056] Furthermore, the four sides 123 of the main frame 121 have uniformly formed weight-reducing sections 124 on their outer surfaces. Each of these weight-reducing sections 124 is composed of an upper and lower combination, with a closed rectangular weight-reducing section 125 provided on the upper part of one side 123 and a rectangular weight-reducing section 126 with a cutout on the bottom side provided on the lower part.

[0057] Furthermore, the weight-reducing portions 125 and 126 are formed as recesses that do not penetrate the side surface 123, along the thickness direction of the side surface 123.

[0058] These weight-reducing sections 125 and 126 are parts where the side surface 123 is hollowed out to reduce the weight of the main frame 121, within a range that ensures the pressure resistance strength of the explosion-proof housing 120 as a pressure-resistant explosion-proof structure. Furthermore, the solid outer edges forming the weight-reducing sections 125 and 126 act as ribs, so that even if the side surface 123 is hollowed out and a thin area is formed, the pressure resistance strength of the side surface 123 can be maintained.

[0059] Although not shown in the diagram, the bottom surface of the main frame 121 has multiple recessed cutouts that do not penetrate the bottom surface, running along the thickness direction of the bottom surface, similar to the valve actuator S1. These cutouts on the bottom surface also contribute to reducing the weight of the main frame 121.

[0060] The explosion-proof housing 120 of the valve actuator S2 also has pressure resistance that can withstand explosion pressures of 0.811 MPa or less, which is the maximum explosion pressure inside it. In addition, the overall weight of the explosion-proof housing 120 has been reduced, so that even when the valve actuator S2 is attached to the valve 2 installed on the piping, the weight is sufficient to prevent deformation or damage to the piping.

[0061] With this structure of valve actuator S1 and valve actuator S2, it is possible to construct a structure in which the explosion-proof housing 110 and explosion-proof housing 120 are made of aluminum while keeping the weight low and ensuring pressure resistance as a pressure-resistant explosion-proof structure.

[0062] However, the structure of explosion-proof housings 110 and 120 presented the following challenges when considering mass production at the product level.

[0063] In other words, if we were to mass-produce explosion-proof housings 110 and 120 from aluminum, we would have to use casting with molds. In this case, as mentioned above, in order to form the honeycomb-shaped cutouts 114 on the side surface 113 and the cutouts on the bottom surface of the main frame 111, at least six molds would be needed, corresponding to the side, top, and bottom surfaces of the main frame 111.

[0064] Furthermore, for the explosion-proof housing 120, in order to form the combination of the closed rectangular cutout 125 on the upper part of the side 123 of the main frame 121 and the rectangular cutout 126 on the lower part with the bottom cutout, as well as the cutout on the bottom, at least six molds corresponding to the side, top, and bottom of the main frame 121 are required.

[0065] A shape requiring six molds like this is a very specialized shape, and compared to the common method of manufacturing with only two molds, an upper mold and a lower mold, the cost of manufacturing the molds is extremely high, and the number of steps during casting is also increased.

[0066] Furthermore, the high costs of manufacturing such specialized molds and the excessive labor involved in manufacturing with these molds are reflected in the price of the final product, placing a significant burden on users who require a large number of products to retrofit and motorize existing manual valves.

[0067] Therefore, the shapes of main frames 111 and 121, which require six molds for casting, presented a problem in that they were difficult to adopt as shapes for production at the product level.

[0068] Therefore, the inventors have developed a pressure-resistant explosion-proof valve actuator that, after considering the shapes of valve actuators S1 and S2, is not only compact and lightweight, but also easy to manufacture as it can be formed by joining two molds.

[0069] The following describes a valve actuator 1, which is an example of a pressure-resistant explosion-proof valve actuator to which the present invention is applied. In the following example, the valve actuator 1 is shown as being installed on a valve 2. That is, the valve actuator 1 functions as an actuator that opens and closes the valve 2.

[0070] Valve 2 is installed in piping 200 (see Figure 10(a)) which is located in an explosive atmosphere containing hydrogen in the air, and is a device that controls or regulates the fluid flowing through the piping. Here, an explosive atmosphere refers to, for example, an environment in which a mixture of hydrogen and air is present, with hydrogen making up 30%.

[0071] Valve 2 is a globe valve comprising a body 20, a handle 21, a valve stem (not shown), and a flange 22 (see Figures 1 and 10(a)). The handle 21 has a frame portion 210 that forms the outer shape, and a plurality of spoke portions 211 that connect the center of the handle 21 to the frame portion 210 (see Figure 10(a)). Since the structure of valve 2 is the same as that of a known globe valve, a detailed explanation is omitted.

[0072] Furthermore, the valve actuator 1 has an explosion-proof housing 10 and a valve mounting portion 4 (see Figures 1 and 2).

[0073] The explosion-proof housing 10 is a component that houses the actuator drive unit 3, which will be described later, and has a pressure-resistant explosion-proof structure. The detailed structure of the explosion-proof housing 10 will be described later.

[0074] Furthermore, the valve mounting portion 4 is fixed to the valve 2 and is a component for supporting the explosion-proof housing 10. Details of the fixing structure of the valve mounting portion 4 to the valve 2 and the connection structure between the explosion-proof housing 10 and the valve mounting portion 4 will be described later.

[0075] Here, the type of valve to which the valve actuator 1 is attached is not particularly limited; the valve actuator 1 can be attached to any valve that has a rotating mechanism such as a handle for controlling the fluid.

[0076] Furthermore, the handle 21 of the valve 2 is not necessarily limited to having a frame portion 210 that constitutes the outer shape and a plurality of spoke portions 211 that connect the center of the handle 21 to the frame portion 210. It is sufficient if it is configured to be able to open and close the valve 2 by fitting into the bracket portion 8, which will be described later. For example, a shape with multiple spoke portions or a plate-shaped handle may be used.

[0077] The detailed structure of the explosion-proof housing 10 will be described. The explosion-proof housing 10 has a main frame 11 that serves as the body for housing the actuator drive unit 3, and a lid 100 that closes the top of the main frame 11 when the actuator drive unit is housed inside (see Figures 1, 2, and 4(a) to 4(c)). The explosion-proof housing 10 is made of aluminum.

[0078] Furthermore, the explosion-proof housing 10 has pressure resistance that can withstand explosion pressures of 0.811 MPa or less, which is the maximum explosion pressure inside it.

[0079] Figure 4(a) also shows the structure of the main frame 11 before housing the actuator drive unit 3.

[0080] This main frame 11 has a box-like shape with an open top and is composed of an internal bottom plate 12 that forms the bottom surface inside, and four side plates 13a, 13b, 13c, and 13d that surround the four side edges of the internal bottom plate (see Figure 4(a)).

[0081] In this main frame 11, the space enclosed by the internal bottom plate 12 and the four side plates 13a, 13b, 13c, and 13d becomes the space in which the gear case 30 of the actuator drive unit 3, which will be described later, is located.

[0082] Furthermore, the internal bottom plate 12 has a roughly donut-shaped stepped portion 140 that is recessed below the top surface 14 of the internal bottom plate 12, and a through hole 141 located inside the stepped portion 140 that penetrates the internal bottom plate 12 in the thickness direction.

[0083] Furthermore, multiple bolt holes 142 are formed in the stepped portion 140. The internal bottom plate 12 is formed with a thickness of 12 mm.

[0084] Furthermore, the stepped portion 140 is responsible for positioning the gear case 30 of the actuator drive unit 3 when it is placed. The through hole 141 is a hole for positioning the bracket portion 8 that connects to the actuator drive unit 3 and rotates. The detailed structure of the bracket portion 8 will be described later. The bolt hole 142 is a hole through which bolts are inserted to fix the gear case 30 to the main frame 11.

[0085] Furthermore, the top surfaces of each of the four side plates 13a, 13b, 13c, and 13d are formed as substantially flat flange portions 130, with a thickness of 18.5 mm. This flange portion 130 thickness corresponds to the maximum thickness of the four side plates 13a, 13b, 13c, and 13d.

[0086] This flange portion 130 is the part that surface-joints with the flange portion 101 (see Figure 4(c)) formed on the lid portion 100. The thickness of the flange portion 130 and the flange portion 101 are designed taking into account the standards for the pressure-resistant explosion-proof structure, which are set according to the type of explosive gas to be targeted and the internal volume of the explosion-proof housing 10 having a pressure-resistant explosion-proof structure, similar to the detailed shape of the main frame 11 which will be described later.

[0087] Specifically, if an explosive gas explodes inside the explosion-proof housing 10, the expanded explosive gas will attempt to move from the inside to the outside of the explosion-proof housing 10. The thicknesses of the flange portions 130 and 101 are designed such that the distance over which the expanded explosive gas moves will be such that its temperature drops below its flash point.

[0088] Furthermore, the flange portion 130 has multiple bolt holes 131 for fixing the cover portion 100 to the main frame 11 (see Figure 4(a)).

[0089] Furthermore, Figure 4(b) is a perspective view of the lid 100 as seen from the top side, and Figure 4(c) is a perspective view of the lid 100 as seen from the bottom side. The lid 100 has a plurality of bolt holes 102 that correspond to the bolt holes 131 described above.

[0090] Furthermore, on the bottom side of the lid portion 100, a flange portion 101 is formed on its side edge, which connects to the flange portion 130 (see Figure 4(c)). Also, the bottom body 103 of the lid portion 100 is formed to be thicker than the flange portion 101. As a result, when the flange portion 130 and the flange portion 101 are joined, the bottom body 103 closes the opening at the top of the main frame 11.

[0091] Furthermore, the top surface 14 of the internal bottom plate 12 and the inner circumferential surfaces of the four side plates 13a, 13b, 13c, and 13d are formed as flat surfaces (see Figure 4(a)). This eliminates any extra space on the top surface 14 and the inner circumferential surfaces of each side plate when explosive gas enters the internal space of the main frame 11, thereby reducing the amount of explosive gas that enters.

[0092] Furthermore, multiple side cutouts 15 are formed on the outer circumferential surface of each of the four side plates 13a, 13b, 13c, and 13d (see Figures 4(a), 5(a) to 5(d)).

[0093] This side cutout section 15 is a part that reduces the thickness of the four side plates 13a, 13b, 13c, and 13d to reduce weight.

[0094] Furthermore, the side cutouts 15 are formed as recesses that do not penetrate each of the four side plates 13a, 13b, 13c, and 13d, along the thickness direction of each side plate. In addition, the side cutouts 15 are formed in a substantially equal arrangement on each of the four side plates 13a, 13b, 13c, and 13d.

[0095] Furthermore, the side cutouts 15 have notches 150 formed on the bottom side, and are shaped so that they do not reach the upper edge of each side plate.

[0096] Furthermore, the positions where the notches 150 of the side cutouts 15 are formed along the vertical direction are the positions where the internal bottom plate 12 is located.

[0097] Furthermore, the side cutouts 15 are formed in such a shape that the width is greatest at the bottom in the vertical direction, and the width gradually decreases from the bottom to the top. In addition, the thicker areas that make up the side cutouts 15 become the rib portions 151.

[0098] Furthermore, in terms of thickness, the thickness of the rib section 151, which corresponds to the maximum thickness of the four side plates 13a, 13b, 13c, and 13d, is 18.5 mm, while the thinnest part of the side cutout section 15 is formed to be 5 mm thick.

[0099] Here, the values ​​for the thickness of the internal bottom plate 12, the flange portion 130, the rib portion 151, and the side cutout portion 15 are examples and can be set appropriately within the range that ensures the desired pressure-resistant explosion-proof strength.

[0100] Furthermore, because a notch 150 is formed on the bottom side of the side cutout section 15, the area of ​​the cutout section with reduced thickness can be made larger for the four side plates 13a, 13b, 13c, and 13d, allowing for efficient weight reduction.

[0101] Furthermore, the side cutouts 15 are formed such that the width is greatest at the bottom in the vertical direction, and the width gradually decreases from the bottom to the top. In addition, the positions where the notches 150 of the side cutouts 15 are formed are the same as the positions where the internal bottom plate 12 is located, resulting in a structure with a balanced pressure resistance in the vertical direction.

[0102] In other words, along the vertical direction, on the upper side of each of the four side plates 13a, 13b, 13c, and 13d, the area occupied by the side cutouts 15 decreases, while the area occupied by the thicker rib portions 151 increases, making it easier to ensure pressure resistance.

[0103] Furthermore, along the vertical direction, the width of the side cutouts 15 increases at the bottom of each of the four side plates 13a, 13b, 13c, and 13d, and the area occupied by the side cutouts 150 increases as notches 150 are formed. However, an internal bottom plate 12 with a certain thickness is located inside each side plate. In other words, even if the area where the thickness is reduced becomes larger, the internal bottom plate 12 can compensate for the reduced pressure resistance.

[0104] Thus, the shape of the side cutouts 15 allows for weight reduction of the four side plates 13a, 13b, 13c, and 13d while maintaining pressure resistance. Furthermore, the formation of multiple rib sections 151 on each side plate also enhances pressure resistance.

[0105] Furthermore, given the shape of the side cutouts 15, the main frame 11 can be cast simply by aligning two molds during manufacturing. In other words, the shapes of the four side plates 13a, 13b, 13c, and 13d, which are provided with the side cutouts 15, can be manufactured by aligning two molds along the vertical direction.

[0106] According to this, the main frame 11 can be mass-produced by casting using only two molds, which is the minimum number required. This reduces the manufacturing cost of the explosion-proof housing 10 and allows it to be manufactured with fewer man-hours.

[0107] Furthermore, the lid portion 100 can also be cast by joining two molds. The casting process is a known technology, and various methods can be employed. While a detailed description is omitted here, one example is that the explosion-proof housing 10 can be manufactured using aluminum die casting.

[0108] Figure 6 also shows the structure of the main frame 11 as viewed from the bottom. On the bottom surface 17 of the main frame 11, a roughly cylindrical projection 16 is formed that extends downward along the vertical direction when viewed from the side of the main frame 11 (see Figures 2, 6, and 8). This bottom surface 17 corresponds to the lower surface of the internal bottom plate 12 (the surface exposed to the outside of the main frame 11).

[0109] This protruding portion 16 is a component that connects to the valve mounting portion 4. Furthermore, the protruding portion 16 is the part that causes the lower structure of the bracket portion 8 (described later) to protrude downward and outward from the main frame 11.

[0110] Furthermore, the protruding portion 16 has a mounting flange 160 and a through hole 162. The mounting flange 160 also has multiple bolt holes 161 (see Figure 6).

[0111] Furthermore, the through hole 162 of the protruding portion 16 communicates with the through hole 141 of the internal bottom plate 12, and serves as the portion through which the lower cylindrical portion of the gear case 30 is inserted.

[0112] Furthermore, the mounting flange 160 is the part to which the actuator drive unit 3 is attached to the through hole 162, and the gear case 30 is attached and fixed to the mounting flange 160 via bolts (not shown) inserted through bolt holes 161. In addition, a bracket portion 8 is inserted through the lower through hole of the gear case 30, and this bracket portion 8 closes off the part of the through hole 162 other than the part through which the gear case 30 is inserted.

[0113] Furthermore, the bottom surface 17 has multiple bottom surface cutouts 170 formed along the vertical direction, with a reduced thickness. In addition, thicker bottom surface rib sections 171 are formed between the bottom surface cutouts 170. That is, the multiple bottom surface cutouts 170 are separated by the bottom surface rib sections 171. The bottom surface cutouts 170 are formed with a thickness of 5.5 mm. The thickness of the rib sections 171 is the same as the maximum thickness of the bottom surface 17 (12 mm, which is the thickness of the internal bottom plate).

[0114] Furthermore, the bottom rib portion 171 is formed to extend substantially radially from the outer edge of the protruding portion 16 when viewed from the bottom. As a result, the bottom surface 17 has a shape in which the bottom cutout portion 170 and the bottom rib portion 171 are evenly distributed.

[0115] These multiple bottom cutouts 170 are designed to reduce the thickness of the bottom surface 17 and thus lighten the weight. In other words, the weight of the main frame 11 is also reduced by the bottom cutouts 170. Furthermore, the even distribution of the bottom cutouts 170 on the bottom surface 17 allows for efficient weight reduction.

[0116] Furthermore, the formation of multiple bottom rib portions 171 increases the pressure resistance strength of the bottom surface 17. In addition, the even distribution of the bottom rib portions 171 on the bottom surface 17 results in a structure with even greater pressure resistance strength.

[0117] Here, it is not necessarily required that multiple bottom surface cutouts 170 be formed on the bottom surface 17. However, as mentioned above, it is preferable that multiple bottom surface cutouts 170 be formed on the bottom surface 17 of the main frame 11, in order to reduce weight while ensuring pressure resistance.

[0118] Furthermore, the numerical value for the thickness of the bottom cutout portion 170 is just an example, and can be set appropriately within the range that ensures the desired pressure-resistant explosion-proof strength.

[0119] Furthermore, along the vertical direction, the direction in which the bottom cutout portion 170 is recessed and the direction in which the bottom rib portion 171 protrudes are parallel to the direction in which the side cutout portion 15 was formed along the vertical direction.

[0120] According to this, when forming the side cutouts 15 on the four side plates 13a, 13b, 13c, and 13d, the bottom surface 17 with the cutouts 170 and bottom rib portion 171 can be formed by casting in which two molds are joined vertically.

[0121] In other words, the main frame 11 can be manufactured using two molds in a single die-clamping operation, with the four side plates 13a, 13b, 13c, and 13d, and the shape of the bottom surface 17. Therefore, the portion of the bottom surface 17 that has been thinned and hollowed out can be formed using two molds in a small number of steps.

[0122] Next, the structure of the actuator drive unit 3 will be described.

[0123] The actuator drive unit 3 includes a gear case 30 (see Figures 3, 7(a), and 7(b)), a motor 5, a belt transmission unit 6, and a worm gear reducer 7 (see Figures 7(a) and 7(b)). The actuator drive unit 3 also includes a servo driver and an operator unit (not shown).

[0124] Furthermore, the gear case 30 is an exterior component that houses the main components constituting the actuator drive unit 3, such as the motor 5, belt transmission unit 6, worm gear reducer 7, servo driver, and operator unit. In Figures 7(a) and 7(b), the gear case 30 is shown with the top plate 31 and gear cap 32 (see Figure 3) removed in order to show the internal structure of the gear case 30.

[0125] Furthermore, the lower side of the gear case 30 is inserted through the through holes 141 and 162 together with the bracket portion 8, and the lower side of the gear case 30 is formed to reach the protruding portion 16 along the vertical direction.

[0126] Furthermore, the motor 5 is the drive source in the actuator drive unit 3, which generates torque to rotate the handle 21 of the valve 2 via the bracket portion 8. The motor 5 is composed of a brushless motor, which is a type of DC motor. The motor 5 also has a rotating shaft (not shown).

[0127] Furthermore, the belt transmission unit 6 is a power transmission mechanism for transmitting power output from the motor 5 to the worm gear reducer 7. The belt transmission unit 6 is also a reduction mechanism that increases torque by reducing the rotational speed of the power output from the motor 5 before transmitting it to the worm gear reducer 7. Power mechanisms like the belt transmission unit 6 are generally also called belt drives.

[0128] The belt transmission unit 6 has a small-diameter pulley 60, a large-diameter pulley 61, and a belt 62 (Figures 7(a) and 7(b)). The small-diameter pulley 60 is attached to the rotating shaft of the motor 5 and rotates integrally with the rotating shaft. The large-diameter pulley 61 is attached to the worm section 70 of the worm gear reducer 7, which will be described later, and rotates integrally with the worm section 70.

[0129] Furthermore, the belt 62 is a belt member stretched over the small-diameter pulley 60 and the large-diameter pulley 61. The irregularities formed on the outer circumferential surfaces of the small-diameter pulley 60 and the large-diameter pulley 61 fit together with the irregularities formed on the inner circumferential surface of the belt 62, so that the small-diameter pulley 60, the large-diameter pulley 61, and the belt 62 rotate as a single unit.

[0130] Here, it is not necessarily required that the irregularities formed on the outer circumferential surfaces of the small-diameter pulley 60 and the large-diameter pulley 61 engage with the irregularities formed on the inner circumferential surface of the belt 62, causing the small-diameter pulley 60, the large-diameter pulley 61, and the belt 62 to rotate as a single unit. For example, the belt 62 may be configured to transmit power through the frictional force generated between it and the small-diameter pulley 60 or the large-diameter pulley 61.

[0131] In this case, the frictional force generated between the small-diameter pulley 60, the large-diameter pulley 61, and the belt 62 can be adjusted so that when a force greater than a certain amount is applied and the transmitted force becomes large, slippage occurs, preventing the transmission of power beyond a certain amount. This prevents the belt 62 from slipping and damaging the valve seal material (not shown) of the valve 2 when a large force is about to be applied that would damage it, thus preventing a decrease in sealing performance.

[0132] Furthermore, the ratio of the diameter of the small-diameter pulley 60 to the diameter of the large-diameter pulley 61 is 1:2. In addition, the rotational speed of the motor 5 can be reduced according to the ratio of the diameters of the small-diameter pulley 60 and the large-diameter pulley 61.

[0133] In other words, a reduction ratio of 1:2 can be obtained in the belt transmission section 6 from the ratio of the diameters of the small-diameter pulley 60 and the large-diameter pulley 61. The torque output from the valve actuator 1 is determined according to this reduction ratio in the belt transmission section 6 and the reduction ratio obtained from the worm gear reducer 7.

[0134] Here, power transmission mechanisms using belts, such as the belt transmission section 6, are generally not used in actuators because they have difficulty transmitting high torque (they are not suitable for transmitting large amounts of power).

[0135] However, as will be described later, the actuator drive unit 3 uses a small motor 5 with an output of 100W, so power can be sufficiently transmitted using a belt-based power transmission mechanism, such as the belt transmission unit 6. As a result, the belt transmission unit 6 can reduce the rotational speed of the motor 5 and increase the torque while transmitting power to the worm gear reducer 7.

[0136] Furthermore, the ratio of the diameter of the small-diameter pulley 60 to the diameter of the large-diameter pulley 61 is not necessarily limited to a ratio of small-diameter pulley 60:large-diameter pulley 61 = 1:2. However, in order to obtain a reduction ratio in the belt transmission section 6, it is preferable that the diameter of the large-diameter pulley 61 be larger than the diameter of the small-diameter pulley 60. Also, from the viewpoint of avoiding an increase in the size of the actuator drive section 3 due to an increase in the size of the belt transmission mechanism 6, it is preferable that the ratio of the diameters is small-diameter pulley 60:large-diameter pulley 61 = 1:2 or less. Moreover, from the viewpoint of achieving both a small size belt transmission mechanism 6 and a high reduction ratio in the belt transmission section 6, it is even more preferable that the ratio of the diameters is small-diameter pulley 60:large-diameter pulley 61 = 1:2.

[0137] Furthermore, it is not necessarily required to use a motor 5 with an output of 100W; the output value is not limited as long as the actuator drive unit 3 can be made smaller. For example, in this invention, a motor with an output of 50 to 100W can be used.

[0138] Furthermore, the worm gear reducer 7 is a reducer that increases torque by further reducing the rotational speed of the power transmitted from the belt transmission section 6 and then transmits it to the bracket section 8. The worm gear reducer 7 also has a reduction ratio of 1:50.

[0139] Furthermore, the worm gear reducer 7 has a worm section 70 and a worm wheel 71 (Figures 7(a) and 7(b)). The worm section 70 and the worm wheel 71 are each provided with gear sections (not shown). In addition, the worm wheel 71 has its rotation axis perpendicular to that of the worm section 70, and power is transmitted by the meshing of the gear sections.

[0140] Furthermore, the lower part of the worm wheel 71 is connected to the outshaft 80, which forms part of the bracket 8 described later (see Figure 8). The worm wheel 71 and the outshaft 80 are configured to rotate as a single unit. The structure of the worm gear reducer 7 can be that of a known harmonic drive gear reducer, and a detailed explanation of its structure is omitted.

[0141] Here, the worm gear reducer 7 is not necessarily limited to one having a reduction ratio of 1:50, and it is possible to use a worm gear reducer with a reduction ratio that is appropriately changed.

[0142] Furthermore, within the gear case 30, when viewed from above, the angle between the motor 5's rotation axis and the belt 62, and the angle between the belt 62 and the worm section 70 are arranged to be approximately 90 degrees, respectively. The worm wheel 71 is also positioned surrounded by the motor 5's rotation axis, the belt 62, and the worm section 70.

[0143] This makes it possible to compactly house the motor 5, belt transmission unit 6, and worm reducer 7 within the limited space of the small gear case 30.

[0144] Furthermore, the bracket portion 8 is a component that rotates the handle 21 of the valve 2 using power transmitted from the worm gear reducer 7. In other words, the bracket portion 8 is the part that applies the torque output from the actuator body 1 to the handle 21 of the valve 2.

[0145] Next, we will explain in detail the bracket portion 8 and its surrounding structure. As shown in Figure 8, the bracket portion 8 has an outshaft 80 and a mounting plate 81. The outshaft 80 is a component whose upper end is connected to the lower part of the worm wheel 71 and which rotates together with the worm wheel 71.

[0146] Furthermore, the mounting plate 81 has multiple spokes 83 attached to its lower end and is a component that transmits the rotational force of the outshaft 80 to the spokes 83 via the mounting plate 81 (see Figure 8). The spokes 83 are components that fit onto the handle 21 of the valve 2 (see Figure 9).

[0147] Furthermore, the lower tip of the outshaft 80 is formed in a tapered rectangular prism shape, and the upper part of the mounting plate 81 that fits with the tip of the outshaft 80 has a recess formed to fit with the rectangular prism (reference numerals omitted).

[0148] Furthermore, bolt holes are formed at the lower tip of the outshaft 80 and the fitting point of the mounting plate 81, and the mounting plate 81 is fixed to the outshaft 80 by bolts 82 attached from below.

[0149] This allows the rotational force of the rotating outshaft 80 to be transmitted to the mounting plate 81, thereby rotating the mounting plate 81 and the spokes 83.

[0150] Furthermore, a ring-shaped bearing 33 is provided on the outer peripheral edge of the upper part of the outshaft 80. In addition, a ring-shaped oil seal 34 is provided on the outer peripheral edge of the middle part of the outshaft 80.

[0151] Although not shown in the diagram, a gasket is installed at the boundary between the top surface 14 and the stepped portion 140 of the internal bottom plate 12 of the main frame 11.

[0152] Furthermore, the spokes 83 of the bracket portion 8 are formed in multiple numbers to match the number of spokes 211 of the handle 21 (see Figure 11(a)).

[0153] Furthermore, the rotating spokes 83 come into contact with the spoke portion 211 of the handle 21 (see Figure 9), and as the rotation of the spokes 83 continues, the handle 21 can be rotated. Note that in Figure 9, in order to clarify the positional relationship between the handle 21 and the spokes 83, the structure above the mounting plate 81 of the bracket portion 8 is omitted from the illustration.

[0154] Furthermore, the longitudinal length of the spokes 83 is formed to be equal to or longer than the stroke distance of the handle 21, which moves up and down when the valve 2 is opened and closed. This makes it possible to move the handle 21 up and down within the range of the spokes 83 of the bracket portion 8 when the handle 21 rotates.

[0155] Thus, the bracket portion 8 is structured to transmit the rotational force generated from the actuator drive unit 3 to the handle 21 via the out shaft 80, mounting plate 81, and spokes 83, thereby opening and closing the valve 2.

[0156] Furthermore, in the valve actuator 1 of the present invention, the total weight of the explosion-proof housing 10, the actuator drive unit 3, and the bracket unit 8 combined is 10 kg or less. That is, the weight of the explosion-proof housing 10 and other components is sufficiently reduced, so that even when the valve actuator 1 is attached to the valve 2 provided in the piping 200, damage or deformation of the piping 200 can be sufficiently suppressed.

[0157] [Motor control mechanism] Furthermore, motor 5 is connected to a control system (not shown) and its drive is controlled. The system that controls the drive of motor 5 is also connected to an absolute encoder (not shown). The absolute encoder is attached to motor 5 and is a component that detects the rotated position information of motor 5 and controls its position in relation to its rotational movement.

[0158] Furthermore, the motor 5 is controlled by a control system consisting of a controller and a servo driver. The controller is a command unit that outputs operation command signals to the servo driver.

[0159] Furthermore, the servo driver is a control unit that outputs pulse signals to the motor 5 or controls its output in accordance with command signals from the controller. The servo driver 51 is a component corresponding to the motor driver in the claims of this application.

[0160] The servo driver also has a lower-level CPU and a higher-level CPU (not shown). The lower-level CPU is a component that transmits pulse signals to the motor 5. The lower-level CPU is a component that acquires position information of the rotational position of the motor 5 from the motor 5's absolute encoder and transmits this rotational position information, along with the result of determining whether or not the position information matches the rotational information instructed by the higher-level CPU, to the higher-level CPU.

[0161] Furthermore, the higher-level CPU is a component that controls the lower-level CPU. The higher-level CPU determines the rotational speed and rotational position of the motor 5 and transmits this rotational information to the lower-level CPU. In addition, the higher-level CPU is configured to enable external communication control of the actuator drive unit 3.

[0162] Furthermore, the higher-level CPU is a component that acquires from the lower-level CPU the position information of the rotational position of motor 5 and the result of a determination of whether or not that position information matches the rotational information instructed by the higher-level CPU. In addition, the higher-level CPU is a component that determines the rotational correction control if the position information of the rotational position of motor 5 does not match the instructed rotational position (theoretical position information) based on the information acquired from the lower-level CPU.

[0163] Conventional valve actuators only contain the lower-level CPU of the present invention within the servo driver (driver CPU), and do not include any components corresponding to the higher-level CPU.

[0164] Therefore, in order to enable autonomous control of the valve actuator by equipping the servo driver with a higher-level CPU, as in the actuator drive unit 3 of the present invention, it becomes necessary to add a main control board to a conventional valve actuator. Adding such a main control board would make the gear case 30 or the actuator drive unit 3 larger.

[0165] Therefore, in the actuator drive unit 3, the servo driver has both a lower-level CPU and a higher-level CPU, which makes it possible to further miniaturize the actuator drive unit 3.

[0166] Next, we will explain the structure of the valve mounting section 4. As described above, the valve mounting portion 4 is a component that is fixed to the valve 2 and supports the explosion-proof housing 10.

[0167] The valve mounting section 4 includes an adapter 40, a mounting plate 41, a stand section 42, and a clamp knob screw 500 (see Figure 9).

[0168] Furthermore, the adapter 40, mounting plate 41, stand portion 42, and clamp knob screw 500 are arranged in pairs, two of each, around the protruding portion 16 of the explosion-proof housing 10.

[0169] Furthermore, the adapter 40 is a component that fixes the integrated structure of the mounting plate 41 and the stand portion 42 to the protruding portion 16.

[0170] Furthermore, the adapter 40 is configured to be attachable and detachable by selecting its position from a plurality of mounting holes 163 (see Figure 11(a)) formed at regular intervals on the outer circumferential surface of the protrusion 16. This allows the explosion-proof housing 10 to be rotated to adjust to the desired orientation and fix the protrusion 16 to the adapter 40.

[0171] As a result, the degree of freedom in the installation position of the explosion-proof housing 10 can be increased to match the structure surrounding the valve 2.

[0172] Furthermore, the mounting plate 41 is a component that connects the adapter 40 and the stand portion 42. The stand portion 42 is a component that fixes the integrated structure of the adapter 40 and the mounting plate 41 to the flange 22 of the valve 2 (see Figure 9).

[0173] Furthermore, the clamp knob screw 500 is a component that detachably secures the mounting plate 41 and the stand part 42. This clamp knob screw 500 can be attached to the mounting plate 41 and the stand part 42 without the use of any separate tools, allowing for easy securing of the mounting plate 41 and the stand part 42.

[0174] The following describes the process of attaching the valve actuator 1 to the valve 2 using the valve mounting section 4, with reference to the drawings.

[0175] First, as shown in Figure 10(a), a manual valve 2 to which the explosion-proof housing 10 is to be installed is provided in the piping 200.

[0176] As shown in Figure 10(b), the stand 42 is attached to the flange 22 of the valve 2 via bolts 420 and nuts 421. One stand 42 can be fixed to the flange 22 with one set of bolts 420 and nuts 421.

[0177] As shown in Figure 10(c), the stand 42 is attached to the other flange 22 via bolts 420 and nuts 421. This completes the process of fixing the stand 42 to the valve 2.

[0178] Next, as shown in Figure 11(a), the adapter 40 and mounting plate 41 are attached to the explosion-proof housing 10. As described above, the adapter 40 can be fixed in a position selected from among a plurality of mounting holes 160 formed at regular intervals on the outer circumferential surface of the protrusion 16.

[0179] The outer surface of the protruding portion 16 is sandwiched and fixed from both sides by the adapter 40, and the adapter 40 and the mounting plate 41 are fixed via bolts 410. With this procedure completed, the work of fixing the adapter 40 and the mounting plate 41 to the explosion-proof housing 10 is finished.

[0180] Next, as shown in Figure 11(b), the positions of the mounting plate 41 and the stand 42 are aligned with the positions of the spokes 83 of the bracket portion 8 and the spokes 211 of the handle 21, and the explosion-proof housing 10 is attached to the valve 2.

[0181] At this point, the mounting plate 41 and the stand 42 are aligned, and the clamp knob screw 500 is inserted through both components to secure the mounting plate 41 and the stand 42.

[0182] With this clamp knob screw 500, the mounting plate 41 and the stand 42 can be fixed together without the need for separate tools or connecting parts. Furthermore, since fixing can be done with a simple operation of inserting the clamp knob screw 500 from the outside to the inside of the mounting plate 41, the clamp knob screw 500 can be easily installed even in the limited workspace of a ship.

[0183] Following the above steps, the installation of the explosion-proof housing 10 onto the valve 2 is completed, as shown in Figure 11(c). In this way, using the valve mounting section 4, the valve actuator 1 can be positioned on the manually operated valve 2 in a simple process, thereby electrifying the valve 2.

[0184] The structure of the valve mounting section 4 described above is merely one example of a structure in which the explosion-proof housing 10 is placed on a valve 2 provided on a predetermined pipe 200. The structure of the valve mounting section 4 can be appropriately designed to match the shape and arrangement of the pipe and valve.

[0185] The actuator drive unit 3 and motor 5 in the present invention can be manufactured in the following sizes, for example.

[0186] First, in the case of the actuator drive unit 3, if it is a structure that can be driven by a DC power supply, the height from the top end of the handle 21 of the valve 2 to the top end of the actuator drive unit 3 can be designed to be 72 mm, the width 157 mm, and the length 170 mm. In addition, the height of the gear case 30 of the actuator drive unit 3 alone can be designed to be 56 mm.

[0187] Furthermore, for motor 5, a size with dimensions of 40mm in height and width, 95mm in length, and 100W output is available. The servo driver 51 can be designed with dimensions of 30mm in width, 80mm in length, and 14mm in height. This motor 5 can achieve performance equivalent to a motor with dimensions of 80mm in height and width, 116mm in length, and 400W output.

[0188] Thus, the actuator drive unit 3 is sufficiently compact yet capable of controlling the opening and closing of the valve 2. Furthermore, the valve actuator 1 is capable of autonomous control, allowing for highly precise control of the rotational movement of the handle 21 without the intervention of an operator.

[0189] As described above, the actuator to which the present invention is applied can be easily attached to a manual valve, enables the motorization of the valve, is sufficiently compact to be placed in a narrow installation space, has excellent power transmission performance, and enables high-precision control. [Explanation of Symbols]

[0190] 1. Valve Actuator 2 valves 20 Body 21 Handle 210 Frame section 211 Spoke section 22 Flange 200 piping 10 Explosion-proof housing 11 Mainframe 100 Lid 101 Flange section 102 bolt holes 103 Base Body 12 Internal bottom plate 13a side plate 13b Side plate 13c side plate 13d side plate 130 Flange section 131 bolt holes 14 Top surface 140 Step section 141 Through hole 142 bolt holes 15 Side cutouts 150 notches 151 Rib section 16 Protrusion 160 Mounting flange 161 bolt holes 162 Through hole 163 mounting holes 17. Bottom 170 Bottom cutout 171 Bottom rib section 3. Actuator drive unit 30 Gear Case 31 Top plate 32 Gear cap 33 Bearings 34 Oil seals 4. Valve mounting section 40 adapters 41 Mounting plate 410 volts 42 Stand Section 420 volts 421 Nut 500 Clamp Knob Screw 5 motors 6. Belt transmission section 60 Small diameter pulley 61 Large diameter pulley 62 belts 7 Worm gear reducer 70 Warm section 71 Worm Wheel 8 Bracket section 80 Outshaft 81 Mounting plate 82 volts 83 spokes S1 Valve Actuator 110 Explosion-proof housing 111 Mainframe 112 Lid 113 Side view 114 Weight reduction section 2 valves S2 Valve Actuator 120 Explosion-proof housing 121 Mainframe 122 Lid 123 Side view 124 Weight reduction section 125 Closed rectangular cutout 126 Rectangular cutout on the bottom side 2 valves

Claims

1. An electrically driven actuator drive unit, A bracket portion is attached to the actuator drive unit and configured to be rotatable by the driving force of the actuator drive unit, and is fitted with the handle of a predetermined valve provided in the piping to open and close the predetermined valve. The actuator drive unit and the explosion-proof housing, which covers at least a portion of the bracket and is made of aluminum and has a pressure-resistant explosion-proof structure, It comprises a valve mounting portion that is attached to the predetermined valve and supports the explosion-proof housing above the handle, The explosion-proof housing comprises a housing body capable of housing the actuator drive unit inside, and a housing lid that is attached to the top surface of the housing body when the actuator drive unit is housed inside the housing body. Multiple side cutouts are formed on the side of the housing body, each having a thickness less than the side surface and with only the bottom end cut out. The inner bottom of the housing body has a predetermined thickness. Pressure-resistant explosion-proof valve actuator.

2. The bottom surface of the housing body is provided with a cylindrical projection that protrudes downward from the bottom surface and has a through hole that communicates with the inside of the housing body. In addition, the bottom surface around the projection has multiple bottom surface cutouts that are thinner than the bottom surface. The pressure-resistant explosion-proof valve actuator according to claim 1.

3. The total weight of the actuator drive unit, the bracket unit, and the explosion-proof housing is 10 kg or less. A pressure-resistant explosion-proof valve actuator according to claim 1 or claim 2.

4. The aforementioned side cutouts are formed in such a shape that their width gradually decreases from the bottom to the top of the side surface of the housing body. A pressure-resistant explosion-proof valve actuator according to claim 1 or claim 2.

5. Multiple side cutouts are formed at regular intervals on at least one side of the housing body. A pressure-resistant explosion-proof valve actuator according to claim 1 or claim 2.

6. The explosion-proof housing has sufficient strength to withstand explosion pressures such that the maximum explosion pressure inside it is 0.811 MPa or less. A pressure-resistant explosion-proof valve actuator according to claim 1 or claim 2.

7. The bottom surface of the housing body has rib portions that separate adjacent bottom surface cutouts and are formed radially around the protruding portion. The pressure-resistant explosion-proof valve actuator according to claim 2.

8. The actuator drive unit is The enclosure case, A motor, which serves as a drive source and is located inside the aforementioned housing case, has a rotating shaft, A first pulley attached to the aforementioned rotating shaft, A second pulley, which is paired with the first pulley and has a larger diameter than the first pulley, The belt stretched over the first pulley and the second pulley, The device comprises a worm section to which the second pulley is attached, and a worm gear reducer located inside the housing case, which is positioned perpendicular to the worm section and transmits power through meshing with the worm section. The bracket portion is attached to the actuator drive unit. A pressure-resistant explosion-proof valve actuator according to claim 1 or claim 2.

9. A casting process in which a housing body, which is a box-shaped body capable of housing an electrically driven actuator drive unit, has multiple side cutouts formed on its sides, each cutout being thinner than the side and having a shape in which only the bottom end is cut out, is cast by pouring aluminum into a first mold and a second mold by joining them together, A housing step is to house the actuator drive unit in the housing body cast in the casting step, and attach a lid to the top surface of the housing body to construct an explosion-proof housing having a pressure-resistant explosion-proof structure. The process includes a step of arranging a bracket portion that rotates with the driving force of the actuator drive unit on the handle of a predetermined valve provided in the piping, and arranging the explosion-proof housing above the handle via the valve mounting portion. Assembly method for pressure-resistant explosion-proof valve actuators.

10. The aforementioned predetermined valve is an existing valve installed in the piping. The method for assembling a pressure-resistant explosion-proof valve actuator according to claim 9.

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