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

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

[0001] The present invention relates to a pressure-resistant explosion-proof valve actuator and an assembly method for the pressure-resistant explosion-proof valve actuator, and more particularly to a small, lightweight pressure-resistant explosion-proof valve actuator and an assembly method for the pressure-resistant explosion-proof valve actuator that can be easily retrofitted to a valve installed in a pipe, enables the valve to be motorized, and can be used in an atmosphere where explosive gas is present.

[0002] 2. Description of the Related Art Conventionally, actuators have been widely used as drive sources for converting energy such as electricity or hydraulic pressure into mechanical movement to operate equipment.

[0003] There are various types of actuators depending on the type of operating principle and the purpose, and a valve actuator has been proposed that is connected to a valve and opens and closes the valve using the rotational force of a motor.

[0004] Furthermore, in the piping of facilities such as chemical plants, power plants, and ships, a large number of valves are used to control the fluids flowing through the piping. In order to reduce the labor required to open and close a huge number of manual valves, there is a strong demand for electrifying the manual valves installed in the piping using valve actuators.

[0005] The need to convert such manual valves to electric valves is not limited to cases where new valves are installed, but is also expected to increase in the future when performing maintenance or renovations on equipment that is already in operation.

[0006] On the other hand, in an atmosphere where explosive gas is present, there is a risk that a malfunction in an electrically driven actuator could ignite the explosive gas and cause an explosion, so an explosion-proof structure is necessary.For example, the adoption of a pressure-resistant explosion-proof structure, which is a type of explosion-proof structure, is being considered.

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

[0008] In conventional actuators having pressure-resistant and explosion-proof structures, a pressure-resistant and explosion-proof structure is constructed specifically for the device in which the actuator is used (see, for example, Patent Document 1).

[0009] Furthermore, in a pressure-resistant explosion-proof structure, the container that encases the actuator, drive unit, etc. must be strong enough to withstand the maximum explosion pressure when explosive gas that has entered the container explodes, so a structure is adopted in which the flange joints that are provided on the outer edges of the container body and lid that make up the container and where they come into contact have a deep depth, giving the container walls a thick wall thickness.In addition, the container is made of heavy material such as iron.

[0010] Patent No. 7420458

[0011] However, these actuators with pressure-resistant and explosion-proof structures designed specifically for the equipment they are intended to be installed on were not designed to be retrofitted to existing equipment, and required the entire existing equipment to be replaced.In other words, it was difficult to apply these actuators to cases where manual valves already installed in piping, etc., were to be converted to electric valves at a later stage while still utilizing them.

[0012] Furthermore, in containers with pressure-resistant explosion-proof structures, the flange joints are deep, the container walls are thick, and the container is made of heavy materials such as iron, so the container inevitably becomes large and heavy.

[0013] For example, inside ships, chemical plants, etc., there are places where multiple pipes are densely arranged in a limited, narrow space, and the pipes are close to each other. In such places, the distance between adjacent pipes is short, making it difficult to secure enough space to install a pressure-resistant, explosion-proof valve actuator, which requires a large container.

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

[0015] The present invention has been devised in light of the above points, and aims to provide a small, 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, that enables the valve to be electrified, and that can be used in an atmosphere where explosive gases or the like are present.

[0016] In order to achieve the above object, the pressure-resistant explosion-proof valve actuator of the present invention comprises: an electrically driven actuator drive unit; a bracket unit 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 specified valve provided on a pipe to open and close the specified valve; the actuator drive unit; an explosion-proof housing that covers at least a portion of the bracket unit and is made of aluminum and has a pressure-resistant explosion-proof structure; and a valve mounting unit that is attached to the specified valve and supports the explosion-proof housing above the handle, wherein the explosion-proof housing has a housing main body that can accommodate the actuator drive unit inside, and a housing lid that is attached to the top side of the housing main body with the actuator drive unit accommodated inside the housing main body, and the side surfaces of the housing main body are formed with a plurality of side lightening portions that are thinner than the side surfaces and have a shape in which only the end on the bottom side is cut out, and the inner bottom of the housing main body is configured to have a predetermined thickness.

[0017] Here, the electrically driven actuator drive unit and the bracket unit, which is attached to the actuator drive unit and configured to be rotatable by the drive force of the actuator drive unit, and which fits into the handle of a specified valve provided in the piping to open and close the specified valve, make it possible to electrically open and close the specified valve via the drive force of the actuator drive unit.

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

[0019] Furthermore, since the explosion-proof housing is made of aluminum, the weight of the explosion-proof housing can be made lighter than in a configuration in which the housing is made of a material with a higher density, such as iron.

[0020] In addition, by attaching the valve mounting portion to a specific valve and supporting the explosion-proof housing above the handle, it is possible to attach the actuator drive portion, bracket portion, and explosion-proof housing to the specific valve via the valve mounting portion.

[0021] Furthermore, the explosion-proof housing has a housing main body capable of accommodating the actuator driving unit inside, and a housing lid that is attached to the top side of the housing main body while the actuator driving unit is accommodated inside the housing main body, thereby enabling the actuator driving unit to be covered by the housing main body and the housing lid.

[0022] Furthermore, by forming a plurality of side cutouts on the side of the housing body that are thinner than the side, it is possible to reduce the weight of the housing body while ensuring the strength required for the pressure-resistant explosion-proof structure by providing a certain thickness to the side of the housing body. In other words, the weight of the entire explosion-proof housing can be reduced, thereby reducing the load on the piping in which the specified valves are installed.

[0023] Furthermore, by forming the multiple side recesses on the side surfaces of the housing body, which are thinner than the side surfaces and have only the bottom-side end cutouts, the number of steps in the manufacturing process can be reduced, making it easier to manufacture the housing body. That is, for example, the housing body can be formed by casting using two molds. Specifically, since the side recesses have only the bottom-side end cutouts, the shape of the side recesses is such that they can be formed by mating two molds: a first mold for the top portion of the housing body and a second mold for the bottom portion of the housing body. Therefore, the housing body can be manufactured using a manufacturing procedure that requires a relatively small number of molds and mating steps, namely, by mating two molds for casting. This reduces the manufacturing effort and reduces manufacturing costs.

[0024] Furthermore, the side surfaces of the housing body are formed with multiple side surface cutouts that are thinner than the side surfaces and have only the bottom edge cutout, and the inner bottom of the housing body has a predetermined thickness, so that the strength required for the pressure-resistant explosion-proof structure can also be ensured at the bottom side of the housing body. That is, since the side surface cutouts formed on the side surfaces of the housing body have the bottom edge cutout, the strength of the bottom side is reduced when viewed from the side alone, but inside the housing body, the inner bottom has a predetermined thickness, so the thick parts of the inner bottom can compensate for the strength of the thinner parts of the bottom side of the side surfaces. As a result, the strength required for the pressure-resistant explosion-proof structure can be ensured across the entire bottom side of the housing body.

[0025] Furthermore, if the bottom surface of the housing body is provided with a cylindrical protrusion that protrudes downward from the bottom surface and has a through-hole that communicates with the interior of the housing body, a bracket attached to the actuator drive unit can be inserted into the through-hole of the protrusion, and the lower end of the bracket can be positioned below the housing body. Also, a valve mounting part can be attached to the protrusion, and a structure can be constructed in which the explosion-proof housing is supported by the valve mounting part.

[0026] Furthermore, if the bottom surface of the housing body is provided with a plurality of bottom-thickness recesses formed around the protrusions, which are thinner than the bottom surface, the bottom surface of the housing body can be given a certain thickness, ensuring the strength required for the pressure-resistant explosion-proof structure while further reducing the weight of the housing body. In other words, the housing body has a structure in which not only the sides but also the bottom surface are recessed, further reducing the weight of the entire explosion-proof housing and reducing the load on the piping in which the specified valves are installed.

[0027] Furthermore, if the total weight of the actuator drive unit, bracket unit, and explosion-proof housing is 10 kg or less, the overall weight made up of the actuator drive unit, bracket unit, and explosion-proof housing can be reduced, further reducing the load on the piping in which a specified valve is installed. That is, for example, since the weight applied when an operator puts their body weight on the valve or piping to open or close the valve is expected to be at most 10 to 20 kg, deformation and damage to the piping can be sufficiently prevented by keeping the overall weight made up of the actuator drive unit, bracket unit, and explosion-proof housing to 10 kg or less.

[0028] Furthermore, if the side surface lightening portion is formed so that its width gradually decreases from the bottom to the top of the side surface of the housing body, it is possible to provide a wide area on the bottom side of the side surface that is thinner than the side surface, i.e., a wide lightened area. Furthermore, because 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 the lightened area on the bottom side of the side surface is wide.

[0029] Furthermore, when multiple side cutouts are formed at regular intervals on at least one side of the housing body, the side cutouts can be efficiently provided over the entire area of ​​one side, making it easier to further reduce the weight of the housing body. Also, since one side has thicker and thinner parts evenly distributed, the housing body as a whole can maintain its pressure resistance because it has a well-balanced shape in terms of thickness.

[0030] Furthermore, if the explosion-proof housing has the strength to withstand an internal maximum explosion pressure of 0.811 MPa or less, it will have the strength required for a sufficient pressure-resistant explosion-proof structure. Note that the maximum explosion pressure of 0.811 MPa is the maximum explosion pressure that occurs when a hydrogen-air mixture with a composition of 30% hydrogen and 70% air explodes. In other words, the explosion-proof housing has the strength required for a pressure-resistant explosion-proof structure against an explosion of a hydrogen-oxygen mixture.

[0031] Furthermore, if the bottom surface of the housing body has ribs that separate adjacent bottom cutouts and are formed radially from the protrusion, the pressure resistance of the bottom surface of the housing body can be improved. Also, the bottom surface of the housing body has thicker and thinner parts evenly distributed, resulting in a well-balanced shape in terms of thickness, making it easier to maintain the pressure resistance of the entire housing body.

[0032] Furthermore, the actuator drive unit includes a motor serving as a drive source having 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 unit to which the second pulley is attached, and a worm reducer having a worm wheel disposed perpendicular to the worm unit and transmitting power by meshing with a gear, and when the bracket unit is attached to the worm reducer, torque can be output from the output of the motor to open and close the valve with the bracket unit. In other words, the valve can be electrically driven by supplying power to the motor.

[0033] Furthermore, when the bracket engages with the handle of a specified valve and is attached to the actuator drive unit, the torque obtained from the motor and worm reducer inside the housing case can be transmitted directly to the valve handle, making it easier to miniaturize the entire actuator.

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

[0035] Furthermore, when the actuator driving unit has a housing case, the motor and other components that make up the actuator driving unit can be housed in the housing case to form a single structure. Furthermore, by housing this housing case in an explosion-proof housing, not only can the actuator driving unit be disposed therein, but the internal space of the explosion-proof housing can be filled with the housing case, thereby reducing the space through which explosive gas can enter the interior.

[0036] Furthermore, in order to achieve the above object, the method of assembling a pressure-resistant explosion-proof valve actuator of the present invention includes a casting step in which a first mold and a second mold are mated and aluminum is poured into the housing body to cast it, the housing body being a box-shaped body capable of accommodating an electrically driven actuator drive unit inside, the housing body having a plurality of side lightening holes formed on its sides that are thinner than the sides and have a shape in which only the end on the bottom side is cut out; an accommodating step in which the actuator drive unit is accommodated in the housing body cast in the casting step and a lid is attached 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 in which a bracket part that rotates by the driving force of the actuator drive unit is placed on the handle of a predetermined valve provided in piping, and the explosion-proof housing is placed above the handle via a valve attachment part.

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

[0038] Furthermore, in the casting process, the housing body can be manufactured with fewer steps by molding a first mold and a second mold together and pouring aluminum to form a housing body with multiple side recesses on its side surfaces, each of which is thinner than the side surfaces and has only the bottom end cutout. That is, the housing body can be formed by molding two molds together. Specifically, the side recesses have a shape in which only the bottom end is cutout from the side surfaces, resulting in a concave-convex shape that can be formed by molding two molds together: a first mold that shapes the portion corresponding to the top of the housing body, and a second mold that shapes the portion corresponding to the bottom of the housing body. Therefore, the housing body can be manufactured using a manufacturing procedure that requires a relatively small number of molds and mold-matching steps, namely, molding two molds together for casting. This reduces manufacturing effort and costs.

[0039] Furthermore, in the accommodation process, the actuator driving unit is accommodated in the housing main body cast in the casting process, and a lid is attached to the top surface of the housing main body to construct an explosion-proof housing having a pressure-resistant explosion-proof structure, whereby the actuator driving unit is covered by the housing main body and the housing lid, and the actuator driving unit is arranged inside the explosion-proof housing.

[0040] Furthermore, in the placement process, a bracket part that rotates by the driving force of the actuator drive part is placed on the handle of a specified valve installed in the piping, and an explosion-proof housing is placed above the handle via the valve mounting part. By doing so, the actuator drive part, bracket part, and explosion-proof housing can be attached to the specified valve, and the valve can be electrified.

[0041] Furthermore, if the specified valve is an existing valve installed in a pipe, an actuator drive unit covered with an explosion-proof housing can be attached to the existing valve, allowing the existing valve to be retrofitted to be electrified.

[0042] The pressure-resistant explosion-proof valve actuator according to the present invention can be easily retrofitted to a valve installed in a pipe, can electrically power the valve, can be used in an atmosphere where explosive gases, etc. are present, and is small and lightweight. The method for assembling the pressure-resistant explosion-proof valve actuator according to the present invention is a method for assembling a pressure-resistant explosion-proof valve actuator that can be easily retrofitted to a valve installed in a pipe, can electrically power the valve, and can be used in an atmosphere where explosive gases, etc. are present, and is small and lightweight.

[0043]

[0023] FIG. 1 is a schematic explanatory diagram showing a valve to which a valve actuator, which is an example of a valve actuator according to the present invention, is attached.

[0024] FIG. 2 is a schematic perspective view showing the overall structure of an explosion-proof housing and a valve mounting section.

[0025] FIG. 3 is a schematic perspective view showing a gear case of an actuator drive section.

[0026] (a) is a schematic perspective view showing a main frame of the explosion-proof housing, and (b) and (c) are schematic perspective views showing a lid of the explosion-proof housing.

[0027] (a) to (d) are schematic views showing four side plates of the main frame.

[0028] FIG. 4 is a schematic view showing the bottom surface of the main frame.

[0029] FIG. 5 is a diagram showing the internal structure of the gear case when the actuator drive section is viewed from above, where (a) is a schematic perspective view and (b) is a schematic plan view.

[0029] FIG. 6 is a schematic cross-sectional view showing a bracket section and its surrounding structure.

[0029] FIG. 7 is a schematic perspective view showing the positional relationship between the bracket section and the valve mounting section, and the structure of the valve mounting section.

[0029] FIG. 8 is a schematic process diagram showing the process of attaching a valve actuator to a manual valve, where (a) is a schematic view showing the structure of the manual valve to be attached, and (b) and (c) are schematic views showing the attachment of a stand section. 10 is a schematic diagram showing the process of attaching a valve actuator to a manual valve, in which (a) is a schematic diagram showing the attachment of an adapter and a mounting plate to a protrusion, (b) is a schematic diagram showing the state where the position of the explosion-proof housing and the position of the stand are aligned, and (c) is a schematic diagram showing the state where the attachment of the explosion-proof housing to the valve is completed. (a) is a schematic diagram showing a valve actuator having an explosion-proof housing with a honeycomb-shaped cutout portion formed on the side, and (b) is a schematic diagram showing a valve actuator having an explosion-proof housing with a closed rectangular cutout portion formed on the side and a rectangular cutout portion with a notched bottom side.

[0044] Hereinafter, embodiments of the present invention will be described for better understanding of the present invention.

[0045] The present inventors have conducted the following investigations in order to construct a small, lightweight pressure-resistant and explosion-proof valve actuator having a pressure-resistant and explosion-proof structure.

[0046] First, the inventors manufactured a pressure-resistant explosion-proof valve actuator, a valve actuator S1 shown in Fig. 12(a) and a valve actuator S2 shown in Fig. 12(b). Note that the valve actuators S1 and S2 differ from the valve actuator 1 described below only in the shape of the side surface of the explosion-proof housing, and the other components are the same.

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

[0048] The explosion-proof housing 110 has a box-shaped main frame 111 that serves as a main body for accommodating 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 formed evenly on the outer periphery of the four side surfaces 113 of the main frame 111. The cutouts 114 are formed as recesses that do not penetrate the side surfaces 113 along the thickness direction of the side surfaces 113.

[0050] The lightening portion 114 is a portion where the side surface 113 is lightened to reduce the weight of the main frame 111 within a range that can ensure the pressure resistance strength of the pressure-resistant explosion-proof structure of the explosion-proof housing 110. In addition, the solid portion of the outer edge that forms the lightening portion 114 becomes a rib, and even if the side surface 113 is lightened to form a thin area, the pressure resistance strength of the side surface 113 can be maintained.

[0051] Although not shown, a plurality of recessed portions that do not penetrate the bottom surface are formed along the thickness direction of the bottom surface on the bottom surface of the main frame 111. These recessed portions on the bottom surface also serve to reduce the weight of the main frame 111.

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

[0053] The valve actuator S2 also has an explosion-proof housing 120, which houses an actuator drive unit (not shown) inside, thereby forming a pressure-resistant and explosion-proof structure (see FIG. 12(b)).

[0054] The valve actuator S2 differs from the valve actuator S1 in the shape of the four side surfaces 123 of the main frame 121 of the explosion-proof housing 120, but the other structures are the same.

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

[0056] Furthermore, lightening holes 124 are formed evenly on the outer periphery of the four side surfaces 123 of the main frame 121. These lightening holes 124 are configured as an upper and lower combination on one side surface 123, with a closed rectangular lightening hole 125 provided on the upper level and a rectangular lightening hole 126 with a notched bottom surface provided on the lower level.

[0057] The lightening holes 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 lightening portions 125 and 126 are formed by removing weight from the side surface 123 to reduce the weight of the main frame 121 within a range that can ensure the pressure resistance strength of the explosion-proof housing 120 as a pressure-resistant explosion-proof structure. In addition, the solid portions of the outer edges that form the lightening portions 125 and 126 become ribs, and the side surface 123 can maintain its pressure resistance strength even when a thin region is formed by removing weight from the side surface 123.

[0059] Although not shown, similar to the valve actuator S1, a plurality of recessed portions that do not penetrate the bottom surface are formed along the thickness direction of the bottom surface on the bottom surface of the main frame 121. These recessed portions on the bottom surface also serve to reduce the weight of the main frame 121.

[0060] For this valve actuator S2, the explosion-proof housing 120 has the pressure resistance strength to withstand an explosion pressure of up to a maximum internal explosion pressure of 0.811 MPa. In addition, the overall weight of the explosion-proof housing 120 has been reduced, and even when the valve actuator S2 is attached to the valve 2 installed on a pipe, the weight is sufficient to prevent deformation or damage to the pipe.

[0061] With this structure of valve actuator S1 and valve actuator S2, the explosion-proof housing 110 and the explosion-proof housing 120 can be formed from aluminum, while keeping the weight small and ensuring the pressure resistance strength required for a pressure-resistant explosion-proof structure.

[0062] However, the structures of the explosion-proof housing 110 and the explosion-proof housing 120 have the following problems when considering mass production of these at the product level.

[0063] That is, when mass-producing the explosion-proof housings 110 and 120 from aluminum, casting using dies is required. In this case, as described above, to form the honeycomb-shaped cutouts 114 on the side surfaces 113 of the main frame 111 and the cutouts on the bottom surface, at least six dies are required, one for each of the side surfaces, top surface, and bottom surface of the main frame 111.

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

[0065] A shape that requires six molds like this is a very special shape, and compared to a typical shape that is manufactured using only two molds, an upper mold and a lower mold, the cost of manufacturing the molds is very high and the number of steps required for casting is also increased.

[0066] Furthermore, the high cost of manufacturing such special molds and the excessive labor required to manufacture them are reflected in the price of the final product, placing a heavy burden on users who require large quantities of products that retrofit existing manual valves to electrify them.

[0067] Therefore, the shapes of the main frames 111 and 121, which require six molds for casting, have been difficult to adopt as shapes for production at the product level.

[0068] Therefore, the inventors developed the shapes of valve actuator S1 and valve actuator S2, and have now come to develop a pressure-resistant, explosion-proof valve actuator that is not only small and lightweight, but also easy to manufacture by joining two molds.

[0069] Below, we will explain 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, a structure is shown in which the valve actuator 1 is provided to a valve 2. In other words, the valve actuator 1 functions as an actuator that opens and closes the valve 2.

[0070] The valve 2 is installed in a pipe 200 (see FIG. 10(a)) that is provided in an explosive atmosphere where hydrogen is contained in the air, and is a device for controlling or adjusting the fluid flowing through the pipe. Note that the explosive atmosphere here is, for example, an environment where a mixture of hydrogen and air contains 30% hydrogen.

[0071] The valve 2 is a globe valve including a body 20, a handle 21, a valve stem (not shown), and a flange 22 (see FIGS. 1 and 10(a)). The handle 21 has a frame 210 that defines the outer shape, and multiple spokes 211 that connect the center of the handle 21 to the frame 210 (see FIG. 10(a)). The structure of the valve 2 is a known globe valve structure, so a detailed description will be omitted.

[0072] The valve actuator 1 also has an explosion-proof housing 10 and a valve mounting portion 4 (see FIGS. 1 and 2).

[0073] The explosion-proof housing 10 is a member that houses the actuator driving unit 3 (described later) inside, and has a pressure-resistant and explosion-proof structure. The detailed structure of the explosion-proof housing 10 will be described later.

[0074] The valve mounting portion 4 is a member that is fixed to the valve 2 and that supports the explosion-proof housing 10. Details of the structure for fixing the valve mounting portion 4 to the valve 2 and the structure for connecting 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 can be attached is not particularly limited, and the valve actuator 1 can be attached to any valve that has a rotation mechanism such as a handle for controlling a fluid.

[0076] Furthermore, the handle 21 of the valve 2 is not necessarily limited to one having a frame 210 that defines the outer shape and a plurality of spokes 211 that connect the center of the handle 21 and the frame 210, but is sufficient as long as it is configured to fit with a bracket 8 (described later) and be able to open and close the valve 2. For example, a shape with a plurality of spokes or a plate-shaped handle may be used.

[0077] The following describes the detailed structure of the explosion-proof housing 10. The explosion-proof housing 10 has a main frame 11, which serves as the main body and houses 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 therein (see FIGS. 1, 2, and 4(a) to 4(c)). The explosion-proof housing 10 is made of aluminum.

[0078] The explosion-proof housing 10 has a pressure resistance strength capable of withstanding an internal explosion pressure of 0.811 MPa or less.

[0079] FIG. 4(a) shows the structure of the main frame 11 before the actuator driving unit 3 is housed therein.

[0080] The 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 of the interior, 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] The space enclosed by the inner bottom plate 12 and the four side plates 13a, 13b, 13c, and 13d of the main frame 11 is the space in which a gear case 30 of the actuator drive unit 3, which will be described later, is disposed.

[0082] In addition, the internal bottom plate 12 is formed with an approximately donut-shaped step portion 140 that is recessed below the top surface 14 of the internal bottom plate 12, and a through hole 141 that is located inside the step portion 140 and penetrates the internal bottom plate 12 in the thickness direction.

[0083] A plurality of bolt holes 142 are formed in the step portion 140. The inner bottom plate 12 is formed to have a thickness of 12 mm.

[0084] The stepped portion 140 is a portion that is responsible for positioning when the gear case 30 of the actuator driving unit 3 is disposed. The through hole 141 is a hole portion for disposing the bracket portion 8 that rotates while connected to the actuator driving unit 3. A detailed structure regarding the disposition of the bracket portion 8 will be described later. The bolt hole 142 is a hole portion for inserting a bolt that fixes the gear case 30 to the main frame 11.

[0085] The top surface of each of the four side plates 13a, 13b, 13c, and 13d is formed as a substantially flat flange 130, and the flange 130 has a thickness of 18.5 mm. The thickness of the flange 130 corresponds to the maximum thickness of the four side plates 13a, 13b, 13c, and 13d.

[0086] This flange portion 130 is a portion that is surface-joined with the flange portion 101 (see FIG. 4(c)) formed on the lid portion 100. The thicknesses of the flange portion 130 and the flange portion 101 are designed taking into consideration the type of explosive gas to be targeted, the internal volume of the explosion-proof housing 10 having the pressure-resistant explosion-proof structure, and other factors, as well as the detailed shape of the main frame 11, which will be described later.

[0087] Specifically, when explosive gas explodes inside the explosion-proof housing 10, the expanding explosive gas attempts to move from the inside to the outside of the explosion-proof housing 10, and the thickness of the flange portion 130 and the flange portion 101 is designed so that the distance during movement is such that the temperature of the expanding explosive gas drops below the flash point.

[0088] The flange portion 130 is also formed with a plurality of bolt holes 131 for fixing the cover portion 100 to the main frame 11 (see FIG. 4( a )).

[0089] 4(b) is a perspective view of the lid 100 as seen from the top side, and FIG. 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 formed therein, which correspond to the bolt holes 131 described above.

[0090] Furthermore, a flange portion 101 is formed on the side edge of the bottom surface of the lid portion 100 to be joined to the flange portion 130 (see FIG. 4(c)). The bottom body 103 of the lid portion 100 is formed to be thicker than the flange portion 101. This results in a structure in which the bottom body 103 closes the opening at the top of the main frame 11 when the flange portion 130 and the flange portion 101 are joined together.

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

[0092] Furthermore, a plurality of side surface lightening portions 15 are formed on the outer peripheral surface of each of the four side plates 13a, 13b, 13c, and 13d (see FIG. 4(a) and FIG. 5(a) to FIG. 5(d)).

[0093] The side surface lightening portions 15 are portions for reducing the thickness of the four side plates 13a, 13b, 13c, and 13d to reduce the weight.

[0094] The side surface cutouts 15 are formed as recesses that do not penetrate through each of the four side plates 13 a, 13 b, 13 c, and 13 d along the thickness direction of each of the four side plates 13 a, 13 b, 13 c, and 13 d. The side surface cutouts 15 are formed at approximately equal intervals on each of the four side plates 13 a, 13 b, 13 c, and 13 d.

[0095] The side surface recesses 15 have notches 150 formed on the bottom side, and are shaped so as not to reach the upper edges of the side plates.

[0096] The position where the notch 150 of the side surface lightening portion 15 is formed along the vertical direction is the position where the inner bottom plate 12 is disposed.

[0097] The side cutout 15 is formed so that its width is greatest at the bottom and gradually decreases from the bottom to the top. The thicker region that forms the side cutout 15 becomes the rib 151.

[0098] In terms of thickness, the thickness of the rib portion 151, which corresponds to the maximum thickness of the four side plates 13a, 13b, 13c, and 13d, is 18.5 mm, and the thickness of the thinnest part of the side cutout portion 15 is 5 mm.

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

[0100] In addition, since the side cutout portion 15 has a notch 150 formed on the bottom side, the range of the cutout portion with reduced thickness can be made larger for the four side plates 13a, 13b, 13c, and 13d, thereby efficiently reducing the weight.

[0101] In addition, the side cutout portion 15 is formed so that its width is greatest at the bottom side in the vertical direction and gradually decreases from the bottom side to the top side, and the position where the notch 150 of the side cutout portion 15 is formed is the position where the internal bottom plate 12 is positioned, resulting in a structure with balanced pressure resistance strength in the vertical direction.

[0102] That is, 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 cutout portion 15 becomes smaller, while the area occupied by the thicker rib portion 151 becomes larger, making it easier to ensure pressure resistance.

[0103] Furthermore, along the vertical direction, the width of the side surface cutouts 15 increases on the bottom side of each of the four side plates 13a, 13b, 13c, and 13d, and the formation of the notches 150 increases the area occupied by the side surface cutouts 15, but the inner bottom plate 12, which has a certain thickness, is located inside each side plate. In other words, even if the area where the thickness is reduced increases, the corresponding pressure resistance strength can be compensated for by the inner bottom plate 12.

[0104] In this way, the shape of the side cutouts 15 can reduce the weight of the four side plates 13a, 13b, 13c, and 13d while ensuring sufficient pressure resistance. Furthermore, the formation of multiple ribs 151 on each side plate also increases the pressure resistance.

[0105] Furthermore, if the shape of the side surface cutouts 15 is such that it is possible to cast the main frame 11 by simply mating two dies when manufacturing the main frame 11, the shape of the four side plates 13a, 13b, 13c, and 13d provided with the side surface cutouts 15 can be manufactured by mating two dies along the vertical direction.

[0106] This allows the main frames 11 to be mass-produced by casting using only two molds, which is the minimum number required, thereby reducing the manufacturing cost of the explosion-proof housing 10 and enabling it to be manufactured with fewer labor hours.

[0107] The lid 100 can also be cast by mating two dies. The casting process is a known technique, and various methods can be used, and a detailed description will be omitted here. However, as an example, the explosion-proof housing 10 can be manufactured by aluminum die casting.

[0108] 6 shows the structure of the main frame 11 as viewed from the bottom side. A generally cylindrical protrusion 16 is formed on the bottom surface 17 of the main frame 11, extending downward along the vertical direction when viewed from the side of the main frame 11 (see FIGS. 2, 6, and 8). Note that 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 protrusion 16 is a member that serves as a connection portion with the valve mounting portion 4. In addition, the protrusion 16 is a portion that causes the lower structure of the bracket portion 8, which will be described later, to protrude downward and outward from the main frame 11.

[0110] The protruding portion 16 is also formed with a mounting flange 160 and a through hole 162. The mounting flange 160 is also formed with a plurality of bolt holes 161 (see FIG. 6).

[0111] The through-hole 162 of the protrusion 16 communicates with the through-hole 141 of the inner bottom plate 12 and serves as the portion through which the lower cylindrical portion of the gear case 30 is inserted.

[0112] The mounting flange 160 is a portion for mounting the actuator driving unit 3 to the through-hole 162, and the gear case 30 is attached and fixed to the mounting flange 160 via bolts or the like (not shown) inserted through the bolt holes 161. The bracket portion 8 is inserted into the lower through-hole of the gear case 30, and this bracket portion 8 closes the portion of the through-hole 162 other than the portion through which the gear case 30 is inserted.

[0113] The bottom surface 17 is formed with a plurality of bottom surface cutouts 170, each having a small thickness along the vertical direction. Thick bottom surface rib portions 171 are formed between the bottom surface cutouts 170. That is, the plurality of bottom surface cutouts 170 are separated by the bottom surface rib portions 171. Each bottom surface cutout 170 is formed with a thickness of 5.5 mm. The thickness of the rib portions 171 is the same as the maximum thickness of the bottom surface 17 (12 mm, which is the thickness of the inner bottom plate).

[0114] In addition, the bottom surface rib portions 171 are formed to extend substantially radially from the outer edge of the protrusion 16 as viewed from the bottom. Therefore, the bottom surface 17 has a shape in which the bottom surface lightening portions 170 and the bottom surface rib portions 171 are evenly arranged.

[0115] The plurality of bottom surface lightening portions 170 are portions for reducing the thickness of the bottom surface 17 to reduce the weight. That is, the weight of the main frame 11 is also reduced by the bottom surface lightening portions 170. Furthermore, by evenly arranging the bottom surface lightening portions 170 on the bottom surface 17, it is possible to efficiently reduce the weight.

[0116] Furthermore, the formation of the plurality of bottom surface ribs 171 can increase the pressure resistance strength of the bottom surface 17. Furthermore, the evenly arranged bottom surface ribs 171 on the bottom surface 17 result in a structure with even higher pressure resistance strength.

[0117] Here, it is not necessarily required to form a plurality of bottom surface lightening portions 170 in the bottom surface 17. However, as described above, it is preferable to form a plurality of bottom surface lightening portions 170 in the bottom surface 17 of the main frame 11, since this allows for weight reduction while also ensuring pressure resistance strength.

[0118] Furthermore, the thickness of the bottom surface recessed portion 170 is an example, and can be set appropriately within a range that ensures the desired pressure-resistant and explosion-proof strength.

[0119] In addition, the direction in which the bottom surface cutout portion 170 is recessed and the direction in which the bottom surface rib portion 171 protrudes along the vertical direction are parallel to the direction in which the above-mentioned side surface cutout portion 15 is formed along the vertical direction.

[0120] As a result, when forming the side cutout portions 15 in the four side plates 13a, 13b, 13c, and 13d, the bottom surface 17 having the cutout portions 170 and the bottom surface rib portions 171 can be formed by casting in which two molds are mated together from above and below.

[0121] In other words, the main frame 11 can be manufactured by clamping the four side plates 13a, 13b, 13c, and 13d and the shape of the bottom surface 17 in one operation using two molds. Therefore, the portion of the bottom surface 17 where the thickness is reduced and the lightening is performed can be formed using two molds with a small number of processes.

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

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

[0124] The gear case 30 is an exterior member that houses the main components that make up the actuator drive unit 3, such as the motor 5, the belt transmission unit 6, the worm reducer 7, the servo driver, and the operator unit. In order to show the internal structure of the gear case 30, Figures 7(a) and 7(b) illustrate the gear case 30 without the top plate 31 and gear cap 32 (see Figure 3).

[0125] In addition, the lower side of the gear case 30, together with the bracket portion 8, is inserted into the through holes 141 and 162, and the lower side of the gear case 30 is formed so as to reach the protrusion portion 16 in the vertical direction.

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

[0127] The belt transmission unit 6 is a power transmission mechanism for transmitting the power output from the motor 5 to the worm reducer 7. The belt transmission unit 6 is also a speed reduction mechanism that increases the torque by reducing the rotational speed of the power output from the motor 5 and transmits it to the worm reducer 7. A power mechanism such as the belt transmission unit 6 is also generally referred to as a belt drive.

[0128] The belt transmission unit 6 has a small diameter pulley 60, a large diameter pulley 61, and a belt 62 (FIGS. 7A and 7B). The small diameter pulley 60 is attached to the rotary shaft of the motor 5 and rotates integrally with the rotary shaft. The large diameter pulley 61 is attached to a worm portion 70 of the worm reducer 7 (described later) and rotates integrally with the worm portion 70.

[0129] The belt 62 is a belt member stretched between the small diameter pulley 60 and the large diameter pulley 61. The unevenness formed on the outer peripheral surfaces of the small diameter pulley 60 and the large diameter pulley 61 and the unevenness formed on the inner peripheral surface of the belt 62 fit together, so that the small diameter pulley 60, the large diameter pulley 61, and the belt 62 rotate integrally.

[0130] Here, it is not necessarily the case that the unevenness formed on the outer peripheral surfaces of the small diameter pulley 60 and the large diameter pulley 61 and the unevenness formed on the inner peripheral surface of the belt 62 fit together to rotate the small diameter pulley 60, the large diameter pulley 61, and the belt 62 integrally. For example, the belt 62 may be configured to transmit power by frictional force generated between the belt 62 and the small diameter pulley 60 or the large diameter pulley 61.

[0131] In this case, the frictional forces 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 level is applied and the transmission force increases, slippage occurs, preventing the transmission of power greater than a certain level. This prevents the belt 62 from spinning freely when a force large enough to damage the valve seal (not shown) of the valve 2 is applied, thereby preventing the valve seal from being damaged and the sealing performance from being reduced.

[0132] The ratio between the diameter of the small diameter pulley 60 and the diameter of the large diameter pulley 61 is small diameter pulley 60:large diameter pulley 61 = 1:2. The rotation speed of the motor 5 can be reduced according to the ratio between the diameters of the small diameter pulley 60 and the large diameter pulley 61.

[0133] That is, a reduction ratio of 1:2 can be obtained in the belt transmission unit 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 the reduction ratio in the belt transmission unit 6 and the reduction ratio obtained from the worm reducer 7.

[0134] Here, a power transmission mechanism using a belt, such as the belt transmission unit 6, is not generally used in actuators because it is difficult to transmit high torque (it is not suitable for transmitting large power).

[0135] However, as will be described later, the actuator driving unit 3 uses a small-sized motor 5 with an output of 100 W, and therefore power can be transmitted sufficiently by a power transmission mechanism using a belt, such as the belt transmission unit 6. As a result, the belt transmission unit 6 can transmit power to the worm reducer 7 while reducing the rotational speed of the power of the motor 5 and increasing the torque.

[0136] Furthermore, the ratio between the diameters of the small diameter pulley 60 and 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 unit 6, it is preferable that the diameter of the large diameter pulley 61 is larger than the diameter of the small diameter pulley 60. Furthermore, from the viewpoint of avoiding an increase in the size of the belt transmission mechanism 6 and therefore an increase in the size of the actuator drive unit 3, it is preferable that the ratio of the diameters of the small diameter pulley 60:large diameter pulley 61 is 1:2 or less. Furthermore, from the viewpoint of achieving both a small size of the belt transmission mechanism 6 and a high reduction ratio in the belt transmission unit 6, it is even more preferable that the ratio of the diameters of the small diameter pulley 60:large diameter pulley 61 is 1:2.

[0137] Furthermore, it is not necessary to use a motor 5 with an output of 100 W, and the output value is not limited as long as it is possible to reduce the size of the actuator driving unit 3. For example, in the present invention, a motor with an output of 50 to 100 W can be used.

[0138] The worm reducer 7 is a reducer that further reduces the rotational speed of the power transmitted from the belt transmission unit 6 to increase the torque and transmits it to the bracket unit 8. The worm reducer 7 has a reduction ratio of 1:50.

[0139] The worm reducer 7 also has a worm portion 70 and a worm wheel 71 (FIGS. 7(a) and 7(b)). The worm portion 70 and the worm wheel 71 are each provided with a gear portion (not shown). The worm wheel 71 is disposed so that its rotation axis is perpendicular to that of the worm portion 70, and is a component that transmits power by meshing with the gear portions.

[0140] The lower part of the worm wheel 71 is connected to an outshaft 80 that forms part of the bracket unit 8 (described later) (see FIG. 8). The worm wheel 71 and the outshaft 80 are configured to rotate integrally. The structure of the worm reducer 7 can be that of a known strain wave gear reducer, and detailed description of the structure will be omitted.

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

[0142] In addition, in a plan view inside the gear case 30, the angle between the rotation shaft of the motor 5 and the belt 62, and the angle between the belt 62 and the worm part 70 are both approximately 90 degrees. Furthermore, the worm wheel 71 is disposed surrounded by the rotation shaft of the motor 5, the belt 62, and the worm part 70.

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

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

[0145] Next, the bracket unit 8 and its surrounding structure will be described in detail. As shown in Fig. 8, the bracket unit 8 has an outshaft 80 and a mounting plate 81. The outshaft 80 has an upper end connected to the lower part of the worm wheel 71 and is a member that rotates together with the worm wheel 71.

[0146] The mounting plate 81 has a plurality of spokes 83 attached to its lower end, and is a member that transmits the rotational force of the outshaft 80 to the spokes 83 via the mounting plate 81 (see FIG. 8). The spokes 83 are also members that fit into the handle 21 of the valve 2 (see FIG. 9).

[0147] In addition, the lower tip of the outshaft 80 is formed in a tapered rectangular column shape, and the portion of the upper part of the mounting plate 81 that fits with the tip of the outshaft 80 has a recess formed therein that fits with the rectangular column (symbol omitted).

[0148] A bolt hole is formed at the fitting point between the lower tip of the outshaft 80 and the mounting plate 81, and the mounting plate 81 is fixed to the outshaft 80 by a bolt 82 attached from below.

[0149] As a result, the rotational force of the rotating outshaft 80 is transmitted to the mounting plate 81, causing the mounting plate 81 and the spokes 83 to rotate.

[0150] A ring-shaped bearing 33 is provided on the outer circumferential edge of the upper portion of outshaft 80. A ring-shaped oil seal 34 is provided on the outer circumferential edge of the middle portion of outshaft 80.

[0151] Although not shown, a gasket is attached to the boundary between the top surface 14 and the step portion 140 in the inner bottom plate 12 of the main frame 11 .

[0152] The bracket portion 8 has a plurality of spokes 83 formed to match the number of spokes 211 of the handlebar 21 (see FIG. 11(a)).

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

[0154] The length of the spokes 83 in the longitudinal direction is set to be equal to or longer than the stroke distance of the handle 21 that moves up and down due to the opening and closing of the valve 2. This allows the handle 21 to move up and down within the range of the spokes 83 of the bracket part 8 when the handle 21 is rotated.

[0155] In this way, the bracket portion 8 is configured to transmit the rotational force generated by the actuator driving portion 3 to the handle 21 via the outshaft 80, the mounting plate 81, and the spokes 83, thereby opening and closing the valve 2.

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

[0157] [Motor Control Mechanism] The motor 5 is connected to a control system (not shown) to control its drive. The system that controls the drive of the motor 5 is also connected to an absolute encoder (not shown). The absolute encoder is attached to the motor 5 and is a component that detects information about the rotational position of the motor 5 and controls the position of the rotational movement.

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

[0159] The servo driver is a control unit that outputs a pulse signal to the motor 5 in response to a command signal from the controller, or controls the output. The servo driver 51 is a component that corresponds to the motor driver in the claims of this application.

[0160] The servo driver also has a lower CPU and a higher CPU (not shown). The lower CPU is a component that transmits pulse signals to the motor 5. The lower CPU is a component that acquires position information of the rotational position of the motor 5 from the absolute encoder of the motor 5, and transmits the information of the rotational position and information on the result of a determination as to whether or not the position information of the rotational position matches the rotation information instructed by the higher CPU to the higher CPU.

[0161] The host CPU is a component that controls the lower CPU. The host CPU determines the rotation speed and rotation position of the motor 5 and transmits the information to the lower CPU as rotation information. The host CPU is also configured to be capable of communication control from outside the actuator drive unit 3.

[0162] The host CPU is also a component that acquires from the lower CPU position information on the rotational position of the motor 5 and information on the result of a determination as to whether or not the position information on the rotational position matches the rotation information instructed by the higher CPU. Furthermore, the higher CPU is a component that determines rotation correction control when the position information on the rotational position of the motor 5 does not match the instructed rotational position (position information of the theoretical value) based on the information acquired from the lower CPU.

[0163] In conventional valve actuators, the servo driver (driver CPU) only has the lower CPU of the present invention, and does not include a member corresponding to the upper CPU.

[0164] Therefore, in a conventional valve actuator, it is necessary to add an additional main control board to provide a host CPU in the servo driver and enable independent control of the valve actuator itself, as in the actuator drive unit 3 of the present invention. Adding such a main control board increases the size of the gear case 30 or the actuator drive unit 3.

[0165] Therefore, in the actuator driving unit 3, the servo driver has a lower CPU and a higher CPU, so that the actuator driving unit 3 can be made even smaller.

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

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

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

[0169] The adapter 40 is a member that fixes the integrated structure of the mounting plate 41 and the stand portion 42 to the protrusion 16 .

[0170] The adapter 40 is configured to be detachable by selecting its position relative to a plurality of mounting holes 163 (see FIG. 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 it to a desired orientation, and then the protrusion 16 can be fixed 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 in accordance with the structure around the valve 2.

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

[0173] The clamp knob screw 500 is a member that detachably fastens the mounting plate 41 and the stand 42. The clamp knob screw 500 can be easily attached to the mounting plate 41 and the stand 42 by simply attaching the clamp knob screw 500 to the mounting plate 41 and the stand 42 without using any additional tools.

[0174] The process of attaching the valve actuator 1 to the valve 2 using the valve attachment portion 4 will be described below with reference to the drawings.

[0175] First, as shown in FIG. 10( a ), a manual valve 2 to which an explosion-proof housing 10 is to be attached is provided in a pipe 200 .

[0176] 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 by one set of bolt 420 and nut 421.

[0177] 10(c), the stand 42 is attached to the other flange 22 via bolts 420 and nuts 421. By following the steps up to this point, the work of fixing the stand 42 to the valve 2 is completed.

[0178] 11(a), the adapter 40 and the mounting plate 41 are attached to the explosion-proof housing 10. As described above, the adapter 40 can be fixed to a selected position relative to the multiple mounting holes 160 formed at regular intervals on the outer circumferential surface of the protruding portion 16.

[0179] The outer peripheral surface of the protrusion 16 is sandwiched and fixed by the adapter 40 from both sides, and the adapter 40 is fixed to the mounting plate 41 via the bolts 410. By following the steps up to this point, the work of fixing the adapter 40 and the mounting plate 41 to the explosion-proof housing 10 is completed.

[0180] Next, as shown in FIG. 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 spoke portions 211 of the handle 21 , and the explosion-proof housing 10 is attached to the valve 2 .

[0181] At this time, the positions of the connecting portions of the mounting plate 41 and the stand 42 are aligned, and the clamp knob screw 500 is inserted through both members to fix the mounting plate 41 and the stand 42 together.

[0182] Fixing with this clamp knob screw 500 allows the mounting plate 41 and stand 42 to be fixed without using any additional tools or connecting members. Furthermore, since fixing can be achieved by the 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 working space on a ship.

[0183] 11(c), the installation of the explosion-proof housing 10 to the valve 2 is completed. In this way, using the valve mounting portion 4, the valve actuator 1 can be disposed on the manual valve 2 in a simple process, and the valve 2 can be made electric.

[0184] The structure of the valve mounting portion 4 described above is merely one example of a structure for arranging the explosion-proof housing 10 on a valve 2 provided on a specified pipe 200, and the structure of the valve mounting portion 4 can be designed appropriately to suit the shape and arrangement of the pipe and valve.

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

[0186] First, when the actuator driving unit 3 is configured to be driven by a DC power source, it can be designed to have a height of 72 mm, a width of 157 mm, and a length of 170 mm from the top end of the handle 21 of the valve 2 to the top end of the actuator driving unit 3. Furthermore, the height of the gear case 30 alone of the actuator driving unit 3 can be designed to be 56 mm.

[0187] The motor 5 can be designed to have a length and width of 40 mm, a length of 95 mm, and an output of 100 W. The servo driver 51 can be designed to have a width of 30 mm, a length of 80 mm, and a height of 14 mm. This motor 5 can exhibit the same performance as a motor with a length and width of 80 mm, a length of 116 mm, and an output of 400 W.

[0188] In this way, the actuator driving unit 3 is sufficiently small yet capable of controlling the opening and closing of the valve 2. Furthermore, the valve actuator 1 is capable of independent control, and is capable of controlling the rotation of the handle 21 with high precision 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, can electrify the valve, is sufficiently compact so that it can be installed in a small installation space, has excellent power transmission performance, and is capable of high-precision control.

[0190] REFERENCE SIGNS LIST 1 valve actuator 2 valve 20 body 21 handle 210 frame portion 211 spoke portion 22 flange 200 piping 10 explosion-proof housing 11 main frame 100 lid portion 101 flange portion 102 bolt hole 103 bottom body 12 inner bottom plate 13a side plate 13b side plate 13c side plate 13d side plate 130 flange portion 131 bolt hole 14 top surface 140 step portion 141 through hole 142 bolt hole 15 side lightening portion 150 notch 151 rib portion 16 protrusion 160 mounting flange 161 bolt hole 162 through hole 163 mounting hole 17 bottom surface 170 bottom lightening portion 171 bottom rib portion DESCRIPTION OF SYMBOLS 3 Actuator drive unit 30 Gear case 31 Top plate 32 Gear cap 33 Bearing 34 Oil seal 4 Valve mounting unit 40 Adapter 41 Mounting plate 410 Bolt 42 Stand unit 420 Bolt 421 Nut 500 Clamp knob screw 5 Motor 6 Belt transmission unit 60 Small diameter pulley 61 Large diameter pulley 62 Belt 7 Worm reducer 70 Worm unit 71 Worm wheel 8 Bracket unit 80 Out shaft 81 Mounting plate 82 Bolt 83 Spoke S1 Valve actuator 110 Explosion-proof housing 111 Main frame 112 Lid unit 113 Side surface 114 Lightening cutout 2 Valve S2 Valve actuator 120 Explosion-proof housing 121 Main frame 122 Lid unit 123 Side surface 124 Lightening portion 125 Closed rectangular lightening portion 126 Rectangular lightening portion with a cutout on the bottom side2 valves

Claims

1. A pressure-resistant explosion-proof valve actuator comprising: an electrically driven actuator drive unit; a bracket unit attached to the actuator drive unit and configured to be rotatable by the driving force of the actuator drive unit, and which fits into a handle of a specified valve provided on piping to open and close the specified valve; an explosion-proof housing which covers at least a portion of the bracket unit and is made of aluminum and has a pressure-resistant explosion-proof structure; and a valve mounting unit which is attached to the specified valve and supports the explosion-proof housing above the handle, wherein the explosion-proof housing has a housing main body capable of accommodating the actuator drive unit therein, and a housing lid which is attached to the top side of the housing main body with the actuator drive unit accommodated inside the housing main body, and the side surfaces of the housing main body are formed with a plurality of side lightening holes which are thinner than the side surfaces and have a shape where only the end parts on the bottom side are cut out, and the inside bottom part of the housing main body has a specified thickness.

2. A pressure-resistant explosion-proof valve actuator as set forth in claim 1, wherein the bottom surface of the housing main body is provided with a cylindrical protrusion that protrudes downward from the bottom surface and has a through-hole that communicates with the interior of the housing main body, and the bottom surface around the protrusion is formed with multiple bottom surface lightening holes that are thinner than the bottom surface.

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

4. A pressure-resistant explosion-proof valve actuator as set forth in claim 1 or claim 2, wherein the side recessed portion is formed so that its width gradually decreases from the bottom to the top of the side of the housing body.

5. A pressure-resistant explosion-proof valve actuator according to claim 1 or claim 2, wherein a plurality of side surface recesses are formed at regular intervals on at least one side surface of the housing body.

6. A pressure-resistant explosion-proof valve actuator according to claim 1 or 2, wherein the explosion-proof housing has a strength capable of withstanding an internal explosion pressure of 0.811 MPa or less.

7. A pressure-resistant explosion-proof valve actuator according to claim 2, wherein the bottom surface of the housing body has ribs that separate adjacent bottom surface recesses and are formed radially from the protrusion.

8. A pressure-resistant explosion-proof valve actuator according to claim 1 or claim 2, wherein the actuator driving unit comprises: a housing case; a motor arranged inside the housing case and serving as a driving source having a rotating shaft; a first pulley attached to the rotating shaft; a second pulley paired with the first pulley and having a diameter larger than that of the first pulley; a belt stretched around the first pulley and the second pulley; a worm section to which the second pulley is attached; and a worm reducer arranged inside the housing case, the worm wheel being arranged perpendicular to the worm section and transmitting power by meshing with a gear with the worm section; and the bracket section is attached to the actuator driving unit.

9. A method for assembling a pressure-resistant explosion-proof valve actuator, comprising: a casting step of joining a first mold and a second mold and pouring aluminum into the housing body to cast a box-shaped body capable of accommodating an electrically driven actuator drive unit inside, the housing body having a plurality of side lightening holes formed on its sides that are thinner than the sides and have a shape in which only the bottom edge is cut out; an accommodating step of accommodating the actuator drive unit in the housing body cast in the casting step and attaching a lid to the top of the housing body to construct an explosion-proof housing with a pressure-resistant explosion-proof structure; and an arrangement step of arranging a bracket part that rotates by the driving force of the actuator drive unit on the handle of a specified valve installed in piping, and arranging the explosion-proof housing above the handle via a valve attachment part.

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