Programmable logic controller, base unit and module unit therefor

Abstract

Programmable logic controller, including: a base unit (1); and several module units (2) connected to the base unit (1), wherein the base unit (1) includes: a substrate (10) having a plurality of base-side connectors (11) that electrically connects the plurality of module units (2) via the plurality of base-side connectors (11); a base housing (12) having an opening (13) through which one of the plurality of base-side connectors (11) is exposed and which houses the substrate (10); and at least one holding part (14a, 14b) for holding a connecting unit (2a), which represents one of the plurality of module units (2), wherein the connecting unit (2a) includes: a module-side connector (20) for connecting to one of the plurality of base-side connectors (11); an engagement mechanism (21) for releasably engaging with the at least one holding part (14a, 14b) of the base unit (1); and a module housing (22) having a fitting protrusion (22a) configured to fit with the base housing (12) and to engage around the module-side connector (20), wherein the programmable logic controller further includes: an elastic member (31) for exerting a force in a first direction, which is a direction in which the connecting unit (2a) moves away from the base unit (1), for pressing the engagement mechanism (21) of the connecting unit (2a) against the at least one holding part (14a, 14b) of the base unit (1); and a sealing member (30) for sealing a gap between the base housing (12) and the fitting protrusion (22a) of the module housing (22), and wherein the at least one holding part (14a, 14b) is provided in plurality and forms a pair (14), and the pair of holding parts (14) has at least one first inclined surface (4a), which is inclined with respect to the first direction such that the force exerted by the elastic member (31) acts in a second direction intersecting the first direction.

Description

Technical FieldThe present disclosure relates to a programmable logic controller, and a base unit and a module unit therefor.Prior ArtA conventional programmable logic controller (hereinafter referred to as a "PLC") includes a base unit and modular units connected to the base unit. A standard input / output module unit is connected to a network interface via a network cable. A gasket having elasticity is attached to a periphery of a connector included in the standard input / output module unit, and similarly, a gasket is attached to the periphery of a connector of a safety circuit unit connected to said connector (see, for example, Reference 1). The document 2 discloses a base module with a housing with openings and connection elements arranged in the surroundings thereof.References cited in the prior art are referencesPatent DocumentsReference 1: Japanese Patent JP 6 865 912 B1Document 2: Patent Application DE 10 2018 133 646 A1Summary of the InventionProblem to be Solved by the InventionFor example, when a modular unit is installed on the base unit, one end of the modular unit is hooked on the base unit, and then the other end of the modular unit is pushed toward the base unit, whereby the modular unit engages the base unit and causes the base unit to support the modular unit. In this case, because the base unit and the module units are not connected by bolts or other means, the module units tend to fluctuate due to external impacts.In the above PLC, when a substrate of the base unit is accommodated in a base housing and a sealing member such as a gasket is provided between the base housing and each module unit to protect the substrate from surrounding water or dust, the sealing member may be twisted or rubbed due to the vibration of the module units caused by external impacts. As a result, the sealing member is easily damaged, and the waterproof and dust-proofness of the sealing member do not adhere.The present disclosure has been made to solve the above problems and to obtain a PLC whose base unit and module units are capable of maintaining water-tightness and dust-tightness of the sealing members.Means for Achieving the ObjectA PLC according to the present disclosure is a programmable logic controller including a base unit; and a plurality of module units to be connected to the base unit, the base unit including: a substrate having a plurality of base-side connectors, and electrically connecting the plurality of module units via the plurality of base-side connectors; a base housing having an opening through which one of the base-side connectors is exposed and which houses the substrate; and at least one holding part for holding a connection unit which is one of the module units, the connection unit including: a module-side connector for being attached to one of the plurality of base-side connectors; an engagement mechanism for detachably engaging with the at least one holding part of the base unit; and a module case having a fitting protrusion configured to fit with the base unit and to engage the module-side connector, and wherein the programmable logic controller further includes: an elastic member for applying a force in a first direction, which is a direction in which the connection unit moves away from the base unit, to press the engagement mechanism of the connection unit against the at least one holding part of the base unit; and a sealing member for sealing a gap between the base housing and the fitting protrusion of the module housing, and wherein the at least one holding part is provided in plural and forms a pair, and the pair of holding parts has at least one first inclined surface inclined with respect to the first direction such that the force applied from the elastic member acts in a second direction intersecting the first direction.A base unit according to the present invention includes: a substrate having a plurality of base-side connectors that electrically connects the plurality of module units via the plurality of base-side connectors; a base housing having openings through which the plurality of base-side connectors are exposed and that houses the substrate; at least one holding part for holding a connection unit constituting one of the plurality of module units; an elastic member for applying a force in a first direction, which is a direction in which the connection unit moves away from the base unit, to press the engagement mechanism of the connection unit against the at least one holding part of the base unit; and a sealing member for sealing a gap between a fitting protrusion of the module case of the connection unit and the base case, wherein the fitting protrusion is formed to fit around the module-side connector of the connection unit to be connected to one of the plurality of base-side connectors, wherein the at least one holding part is provided in plural and forms a pair, and the pair of holding parts has at least one first inclined surface inclined with respect to the first direction such that the force applied by the elastic member acts in a second direction intersecting the first direction.A module unit according to the present invention includes: a module-side connector to be attached to a base-side connector of the base unit; an engagement mechanism to be detachably engaged with the at least one holding part of the base unit; a module case having a fitting protrusion formed to fit with the base unit and to engage the module-side connector; an elastic member for applying a force in a first direction, which is a direction in which the connection unit moves away from the base unit, to press the engagement mechanism of the module unit against the at least one holding part of the base unit; a sealing member for sealing a gap between the base housing and the fitting protrusion of the module housing, wherein the at least one holding part is provided in plural and forms a pair, and the pair of holding parts has at least one first inclined surface inclined with respect to the first direction such that the force applied from the elastic member acts in a second direction intersecting the first direction.Effects of the InventionAccording to the present invention, it is possible to obtain a PLC, a base unit of a PLC, and modular units of a PLC capable of maintaining water-tightness and dust-tightness by sealing members.Brief Description of the DrawingsFIG. 1 is a perspective view of a PLC according to Embodiment 1. FIG. 2 is a perspective view of a base unit according to Embodiment 1. FIG. 3 is a B-B' cross-sectional view of the base unit according to the embodiment. FIG. 4 is a perspective view of a second holding part according to Embodiment 1. FIG. 5 is a perspective view of a connection unit according to Embodiment 1. FIG. 6 is a perspective view of a second engaging part according to Embodiment 1. FIG. 7 is an A-A' cross-sectional view of the PLC according to Embodiment 1. FIG. 8 is a C-C' cross-sectional view of the PLC according to Embodiment 1. FIG. 9 is a D-D' cross-sectional view of the PLC according to Embodiment 1. FIG. 10 is a plan view of the PLC according to Embodiment 1. FIG. 11 is an A-A' cross-sectional view showing a modification of the PLC according to Embodiment 1. FIG. 12 is a front view showing a modification of the base unit according to Embodiment 1. FIG. 13 is an A-A' cross-sectional view of the PLC according to Embodiment 2. FIG. 14 is an A-A' cross-sectional view showing a modification of the PLC according to Embodiment 2. FIG. 15 is a perspective view of a base unit according to Embodiment 3. FIG. 16 is a perspective view of a connection unit according to Embodiment 3. FIG. 17 is a plan view of a PLC according to Embodiment 3. FIG. 18 is a plan view of the PLC according to Embodiment 3. FIG. 19 is a perspective view of a base unit according to Embodiment 4. FIG. 20 is a perspective view of a connection unit according to Embodiment 4. FIG. 21 is a plan view of a PLC according to Embodiment 4.DESCRIPTION OF THE EMBODIMENTSEmbodiment 1A PLC according to Embodiment 1 will now be described. Note that the same reference numerals denote the same or equivalent configurations in each drawing. As shown in FIG. 1, the PLC includes a base unit 1 and a plurality of modular units 2. the plurality of modular units 2 are attached side by side to the base unit 1. Each of the module units 2 to be connected to the base unit 1 is referred to as a connection unit 2a.In the following description, the direction in which the connection unit 2 amoves away from the base unit 1 is referred to as the longitudinal direction, and the direction parallel to the direction in which the module units 2 are arrayed is referred to as the lateral direction. The lateral direction is a direction intersecting the longitudinal direction, and is perpendicular to the longitudinal direction and the height direction to be described later. In addition, the side of the base unit 1 with respect to the module units 2 is referred to as a rear side, and the side of the module units 2 with respect to the base unit 1 is referred to as a front side, as the case may be. Note that the longitudinal direction corresponds to a first direction, and either the lateral direction or the height direction described below corresponds to a second direction.A perspective view of the base unit 1 is shown in Fig. 2, and a B-B' cross-sectional view of the base unit 1 is shown in Fig. 3. The base unit 1 includes a substrate 10 and a base housing 12 that houses the substrate 10. The substrate 10 includes a plurality of base-side connectors 11. The substrate 10 electrically connects the plurality of module units 2 via the plurality of base-side connectors 11 by connecting each module-side connector 20 to one of the base-side connectors 11.The base housing 12 includes a front cover 12 aand a rear cover 1 b. The front cover 12 ais, for example, a resin member or a metal member. The back cover is, for example, a press-formed metal member. The base case 12 houses the substrate 10 by sandwiching it between the front cover 12 aand the rear cover 12 b. Further, a gasket 16 is sandwiched between the front cover 12 aand the rear cover 12 b. Because the seal is provided to grip the substrate 10, water or dust can be prevented from entering between the front cover 12 aand the rear cover 12 b, and the substrate is not exposed to water or dust.In the front cover 12a, recesses 18 of a rounded rectangular shape are formed, which recesses are recessed toward the rear. Each of the recesses 18 is a fitting mortis (pin hole) that receives a fitting protrusion 22 aof a module case 22, which will be described later. Further, each of the recesses 18 has an opposing surface 18 athat faces a side surface 22 aof the fitting protrusion 22 a, which will be described later. Further, each of the recesses 18 has an opening 13 through which one of the plurality of base-side connectors 11 of the substrate 10 is to be exposed.The front cover 12a has a plurality of holding portions for holding the connection units 2a. The plurality of holding parts are provided in pairs. Each pair of holding parts 14 formed in the plurality of holding parts is referred to as a pair of holding parts 14. A first holding part 14 awhich is one of the paired holding parts 14 is formed in such a manner as to extend forward from one end of the front cover 12 ain the longitudinal direction. A second holding part 14 b, which is one of the paired holding parts 14, is formed in such a manner as to extend forward from the other end of the front cover 12 ain the longitudinal direction. Therefore, the first holding part 14 aand the second holding part 14 bface each other across the opening 13. The height direction is a direction parallel to the direction from the first holding part 14 ato the second holding part 14 b. The height direction is a direction intersecting the longitudinal direction.Ends on both sides in the lateral direction and the end of the front side of the first holding part 14a project straight upward toward the second holding part 14b. The first holding member 14a has inclined surfaces 4a inclined with respect to the longitudinal direction so that the force due to a leaf spring 31, which will be described later, is applied in the lateral direction. The plurality of inclined surfaces 4 aare provided such that each of the first engaging parts 21 a, which will be described later, of the connection units 2 ais sandwiched from both sides in the lateral direction, and the distance between the inclined surfaces 4 agradually narrows toward the longitudinal direction.FIG. 4 is a perspective view of the second holding part 14 b, as viewed from the first holding part 14 aside. As shown in FIG. 4, the ends on both sides in the longitudinal direction and the end of the front side of the second holding part 14 bprotrude straight downward toward the first holding part 14 a. The second holding member 14 bhas inclined surfaces 4 bwhich are inclined with respect to the longitudinal direction such that the force due to a leaf spring 31, which will be described later, is applied in the lateral direction. The plurality of inclined surfaces 4 bare provided such that each of the second engaging parts 21 b, which will be described later, of the connection units 2 ais sandwiched from both sides in the lateral direction, and the distance between the inclined surfaces 4 bgradually narrows toward the longitudinal direction.As shown in FIG. 2, the front cover 12 aincludes a plurality of guide parts 15 configured to extend from the other end of the front cover 12 ain the longitudinal direction. The guide parts 15 each have the shape of a hollow rectangular parallelepiped that is open on both sides in the height direction. The plurality of guide members 15 are provided such that at least two of the plurality of guide members 15 are brought into proximity with each module case 22, which will be described later, when the connection units 2 aare supported by the base unit 1. In the present embodiment, the guide members 15 are arranged such that two of the guide members are brought into proximity to each module case 22, which will be described later, when the connection units 2 aare supported by the base unit 1.FIG. 5 is a perspective view of the connection unit 2 awhich is one of the plurality of module units 2 as viewed from the rear side. The connection unit 2 aincludes the module-side connector 20 connected to one of the base-side connectors 11. Further, the connection unit 2 aincludes the module housing 22, the module housing 22 has the fitting protrusion 22 aof a rounded rectangular shape that fits into one of the recesses 18 of the front cover 12 aof the base housing 12 and engages around the module-side connector 20. The link unit 2a includes an engaging mechanism 21 which engages detachably with a pair of the holding pieces 14 of the base unit 1. The engagement mechanism 21 includes a first engagement part 21 aand a second engagement part 21 b. The engagement mechanism 21 is provided such that the first engagement part 21 aengages with the first holding part 14 aat one end and the second engagement part 21 bon the other end of the module case 22 in the height direction engages with the second holding part 14 b, respectively.The first engaging part 21a has inclined surfaces 5a which will be described later. FIG. 6 is a perspective view of the second engaging part 21 b. The second engaging part 21 bhas inclined surfaces 5 bwhich are inclined with respect to the longitudinal direction such that the force due to the leaf spring 31 is applied in the lateral direction. The inclined surfaces 5b are formed inclined so that the width in the lateral direction becomes gradually narrower toward the longitudinal direction. The inclined surfaces 5b are brought into contact with the inclined surfaces 4b of the second holding member 14b when the connecting unit 2a is supported by the base unit 1.The second engaging part 21 bhas inclined surfaces 5 cthat are inclined such that the force due to the leaf spring 31 is applied in the lateral direction. The inclined surfaces 5 care formed inclined such that the width gradually becomes wider in the lateral direction toward the longitudinal direction. The module housing 22 has a plurality of inclined surfaces 5 din such a way that each of the second engagement parts 21 bis gripped from both sides in the manner of a sandwich. Each pair of inclined surfaces 5d is formed such that the distance therebetween gradually becomes wider toward the longitudinal direction. The inclined surfaces 5c of the second holding part 14b and the inclined surfaces 5d of the module case 22 are brought into contact with each other when the connecting unit 2a is held by the base unit 1.As shown in FIG. 5, the module case 22 has notches 22 bformed to extend along the plurality of front cover guide parts 15 on both sides of the module case 22 in the lateral direction. Each notch 22 bis shaped like a notch after a rectangular parallelepiped is removed. By the notches 22b formed as described above, a portion of the module case is placed between the second holding member 14b and one of the guide members 15 of the base unit 1 when the connecting unit 2a is supported by the base unit 1.A packing 30, which is a sealing member for sealing the gap between the base housing 12 and the fitting protrusion 22 aof the module housing 22, is provided on the lateral side 22 aa, which is a part of the fitting protrusion 22 aof the module housing 22 and parallel to the longitudinal direction. The leaf spring 31, which is an elastic component, is provided on the side of the module housing 22 facing the base unit 1.Next, a mechanism for reducing the load of the gasket 30 in the PLC configured as above will be described.FIG. 7 is an A-A' cross-sectional view of the PLC in a state where the connection unit 2a is supported by the base unit 1. The first engaging part 21a of the connecting unit 2a and the first holding part 14a of the base unit 1 are engaged, and the second engaging part 21b of the connecting unit 2a and the second holding part 14b of the base unit 1 are engaged, so that the connecting unit 2a is supported by the base unit 1. At this point, the base-side connector 11 and the module-side connector 20 are connected. Because the leaf spring 31 contacts the back cover 12 band exerts a force in the longitudinal direction, the engagement mechanism 21 of the connection unit 2 ais pressed against the pair of holding parts 14 of the base unit 1.Even when an external force is applied in the direction from the connection unit 2 ato the base unit 1, that is, when an external force is applied in the direction opposite to the longitudinal direction, the external force can be counteracted by the force applied by the leaf spring 31 in the longitudinal direction. Therefore, since the vibration of the connection unit 2 ais suppressed, the load on the gasket 30 can be reduced.FIG. 8 is a C-C enlarged cross-sectional view of an engaging portion of the first holding part 14 aand the first engaging part 21 a. The first holding part 14a has inclined surfaces 4a inclined so that the width in the lateral direction becomes gradually narrower toward the longitudinal direction. The first engaging portion 21a has inclined surfaces 5a inclined with respect to the longitudinal direction so that the force exerted by the leaf spring 31 acts in the lateral direction. The inclined surfaces 5a are inclined such that the width in the lateral direction becomes gradually narrower toward the longitudinal direction.The inclined surfaces 4a of the first holding member 14a and the inclined surfaces 5a of the first engaging member 21a are brought into contact with each other when the connecting unit 2a is supported by the base unit 1. By the inclined surfaces 5a pressed against the inclined surfaces 4a due to the force of the leaf spring 31, the force of the leaf spring 31 is converted into a force in the lateral direction. Therefore, even when an external force is applied in the lateral direction, the external force is counteracted by the force in the lateral direction transformed by the inclined surfaces 4 aor the inclined surfaces 5 a. As a result of this suppression, the vibration of the connection unit 2 acan be suppressed, so that the load on the gasket 30 can be reduced.FIG. 9 is an enlarged D-D' cross-sectional view showing an engaging portion of the second holding member 14b and the second engaging member 21b. As shown in FIG. 9, the inclined surfaces 4b of the second holding part 14b and the inclined surfaces 5b of the second engaging part 21b are brought into contact with each other when the connecting unit 2a is supported by the base unit 1. By the inclined surfaces 5b pressed against the inclined surfaces 4b due to the force of the leaf spring 31, the force of the leaf spring 31 is converted into a force in the lateral direction. Therefore, even when an external force is applied in the lateral direction, the external force is counteracted by the force in the lateral direction transformed by the slanted surfaces 4 bor the slanted surfaces 5 b,so that the load on the gasket 30 can be reduced.When the connecting unit 2a is supported by the base unit 1, the second engaging part 21b engages with the second supporting part 14b, which narrows the distance between the inclined surfaces 5c of the second engaging part 21b and the inclined surfaces 5d of the module case 22. As a result, the inclined surfaces 5c and the inclined surfaces 5d are brought into contact with each other. At this point, the inclined surfaces 5c are pressed against the inclined surfaces 5d. This applied force is converted into the force in the lateral direction by the inclined surfaces 5c or the inclined surfaces 5d. Therefore, the external force is counteracted by the force in the lateral direction transformed from the slanted surfaces 4 bor the slanted surfaces 5 b, and the vibration of the connection unit 2 acan be suppressed, so that the load on the gasket 30 can be reduced.FIG. 10 is an enlarged plan view of the adjacent portions of the guide part 15 and the module case 22 when an external force is applied in the lateral direction. Portions of the module case 22 sandwiched between the second holding part 14 band the guide part 15 come into contact with the second holding part 14 band the guide part 15 when an external force in the lateral direction is applied. As described above, by having portions of the module case 22 come into contact with the second holding part 14 band the guide part 15, it is possible to restrain further displacement of the connection unit 2 ain the lateral direction. That is, it is possible to reduce the vibration of the connection unit 2 a.In the PLC provided with a packing 30 sealing the engagement mechanism 21 of the connection unit 2 aagainst a pair of holding parts 14 of the base unit 1 by applying a longitudinally directed force as described above and a packing 30 sealing the gap between the base housing 12 and the fitting protrusion 22 aof the module housing 22, even if an external force is applied in the direction opposite to the longitudinal direction, it is possible to counteract the external force because the leaf spring 31 applies the force in the longitudinal direction. Therefore, since the vibration of the connection unit 2 acan be suppressed, the load on the gasket 30 can be reduced. As a result, the gasket 30 is less easily damaged by twisting, rubbing, or the like, and the waterproof and dust-proofness of the gasket 30 can be obtained.At one end of the front cover 12, the first holding part 14a and the first engaging part 21a are engaged, and at the other end thereof, the second holding part 14b and the second engaging part 21b are engaged. Further, at the other end of the front cover 12, a portion of the module case 22 is sandwiched between the guide part 15 and the second holding part 14 b. As described above, since the external force in the lateral direction can be suppressed at both ends in the height direction, it is possible to further reduce the load on the gasket 30. Therefore, the gasket 30 is less easily damaged, and the water-proofness and the dust-proofness of the gasket 30 can be obtained.Further, in the PLC according to Embodiment 1, the gasket 30 for sealing the gap between the base housing 12 and the fitting protrusion 22 aof the module housing 22 is provided on the side surface 22 a aof the fitting protrusion 22 aof the module housing 22. By disposing the packing 30 as described above, it is possible to prevent the gap between the base housing 12 and the fitting protrusion 22 aof the module housing 22 from being widened by the force of the leaf spring 31 toward the longitudinal direction. Therefore, the water-proofness and the dust-proofness of the gasket 30 can be obtained.Further, in the PLC according to Embodiment 1, the inclined surfaces 4 aand 4 bof the pair of holding parts 14 are inclined with respect to the longitudinal direction so as to apply the force of the leaf spring 31 in the lateral direction. In other words, the inclined surfaces 4 aof the first holding part 14 aare inclined such that the width in the lateral direction becomes gradually narrower toward the longitudinal direction. The inclined surfaces 4b of the second holding member 14b are formed such that the distance between the two inclined surfaces 4b gradually becomes narrower toward the longitudinal direction. By forming the inclined surfaces 4 aand 4 bas described above, the force applied from the leaf spring 31 toward the longitudinal direction is converted into the force in the lateral direction. Therefore, even when an external force is applied in the lateral direction, the external force is counteracted by the force in the lateral direction converted by the inclined surfaces 4 aand 4 b. Therefore, by suppressing the vibration of the connection unit 2 a, it is possible to reduce the load of the gasket 30. As a result, the gasket 30 is less easily damaged, and the water-proofness and the dust-proofness of the gasket 30 can be obtained.Further, in the PLC according to Embodiment 1, the inclined surfaces 5 aand 5 bof the engagement mechanism 21 are inclined with respect to the longitudinal direction so as to apply the force of the leaf spring 31 in the lateral direction. In other words, the inclined surfaces 5 aof the first engaging part 21 aare inclined such that the width in the lateral direction becomes gradually narrower toward the longitudinal direction. The inclined surfaces 5 bof the second engaging part 21 bare formed such that the width in the lateral direction becomes gradually narrower toward the longitudinal direction. By forming the inclined surfaces 5 aand 5 bas described above, the force applied from the leaf spring 31 toward the longitudinal direction is converted into the force in the lateral direction. Therefore, even when an external force is applied in the lateral direction, the external force is counteracted by the force in the lateral direction converted by the inclined surfaces 5 aand 5 b. Therefore, by suppressing the vibration of the connection unit 2 a, it is possible to reduce the load of the gasket 30. As a result, the gasket 30 is less easily damaged, and the water-proofness and the dust-proofness of the gasket 30 can be obtained.Further, in the PLC according to Embodiment 1, the inclined surfaces 5 dof the module case 22 are inclined such that the width in the lateral direction gradually becomes wider toward the longitudinal direction. When the connecting unit 2a is supported by the base unit 1, the second engaging part 21b engages with the second supporting part 14b, which narrows the distances between the inclined surfaces 5c of the second engaging part 21b and the inclined surfaces 5d of the module case 22. As a result, the inclined surfaces 5c and the inclined surfaces 5d are brought into contact with each other. At this point, the inclined surfaces 5c are pressed against the inclined surfaces 5d. This applied force is converted into a lateral direction force by the inclined surfaces 5 cor the inclined surfaces 5 d. Therefore, even when an external force is applied in the lateral direction, the external force is counteracted by the force in the lateral direction converted by the inclined surfaces 5 cor 5 d. Therefore, it is possible to suppress the vibration of the connection unit 2 a, so that the load on the gasket 30 can be reduced. As a result, the gasket 30 is less easily damaged, and the water-proofness and the dust-proofness of the gasket 30 can be obtained.Further, in the PLC according to Embodiment 1, the base unit 1 is provided with the plurality of guide parts 15 formed such that they extend in the longitudinal direction, and the module case 22 is provided with the grooves 22 bformed such that they come to lie along the plurality of guide parts 15. Thus, when the connecting unit 2a is supported by the base unit 1, two of the plural guide members 15 are brought into proximity with the module case 22. At this point, a portion of the module case 22 is placed between the second holding part 14 band one of the guide parts 15. The module case 22 is brought into contact with the second holding part 14 band the guide parts 15 when an external force in the lateral direction is applied. Therefore, it is possible to restrain further displacement of the connection unit 2 ain the lateral direction. That is, since the vibration of the connection unit 2 acan be suppressed, the load on the gasket 30 can be reduced. Thus, the gasket 30 is less easily damaged, and the water-proofness and the dust-proofness of the gasket 30 can be obtained.An example has been described above in which two of the plurality of guide members 15 are brought into proximity with the module case 22 when the connection unit 22 is supported by the base unit 1. However, it is also possible to form the guide parts 15 in such a way that three or more of them are brought into the vicinity of the module housing 22. Further, the guide parts 15 need not be formed at the other end of the front cover 12 a, but may be formed at one end of the front cover 12 aor between the one end and the other end of the front cover 12 a.Note that the guide parts 15 may have a rectangular parallelepiped shape that is not open in the height direction.The pair of holding parts 14 of the base unit 1 may be formed to extend from the back cover 12 b.Note that the first holding part 14 aof the base unit 1 may be formed to extend from the other end of the front cover 12 a, and the second holding part 14 bof the base unit 1 may be formed to extend from the one end of the front cover 12 a. In this case, the engagement mechanism 21 of the connection unit 2 ais configured such that the first engagement part 21 aengages with the first holding part 14 aand the second engagement part 21 bengages with the second holding part 14 bat one end and the other end of the module case in the height direction, respectively.Although an example in which the pair of holding parts 14 of the base unit 1 extend from the front cover toward the longitudinal direction has been described above, it is also possible, as shown in FIG. 11, to form the first engaging part 21 aand the second engaging part 21 bof the connection unit 2 ato extend toward the direction opposite to the longitudinal direction. In this case, the pair of holding members 14 may have any shape as long as the engaging mechanism 21 can be engaged with the pair of holding members 14. For example, the engagement mechanism 21 can be engaged with the pair of holding parts 14 by hooking the engagement mechanism 21 into the pair of holding parts 14. Even with such a configuration, the base unit 1 can support the connection unit 2 a.Note that the seal 30 may be provided on the opposite side 18 aof each of the recesses 18 of the base housing 12 facing the side surface 22 aaof the fitting protrusion 22 ain such a manner as to seal the gap between the base housing 12 and the fitting protrusion 22 aof the module housing 22. FIG. 12 is a front view when the gasket 30 is disposed on the opposing surface 18.Note that the elastic member is not limited to the leaf spring 31, and may be any member because it is capable of applying a force toward the longitudinal direction, such as a coil spring or a rubber member. Further, although an example in which the leaf spring 31 is provided on the connection unit 2 ais described, it may be provided on the module unit 22 side of the base unit 1.Even in the PLC configured as described above, when an external force is applied in the direction opposite to the longitudinal direction, the force in the longitudinal direction is applied from the leaf spring 31, so that the external force is counteracted. As a result, the vibration of the connection unit 2 acan be suppressed, so that the load on the gasket 30 can be reduced. As a result, the gasket 30 is less easily damaged by twisting, rubbing, or the like, and the waterproof and dust-proofness of the gasket 30 can be obtained.Embodiment 2In Embodiment 1, an example has been described in which a pair of holding parts 14 of the base unit 1 and the engagement mechanism 21 of the module unit 22 have the inclined surfaces inclined with respect to the longitudinal direction so as to apply the force applied from the leaf spring 31 in the lateral direction. In Embodiment 2, an example in which a pair of holding parts 14 and the engagement mechanism 21 have inclined surfaces inclined with respect to the longitudinal direction so as to apply the force in the height direction applied by the leaf spring 31 will now be described. Specifically, the directions of inclination of the inclined surfaces of the pair of holding members 14 and the inclined surfaces of the engagement mechanism 21 are different from those in Embodiment 1.FIG. 13 shows an A-A' cross-sectional view of the PLC in a state where the connection unit 2a is supported by the base unit 1. As shown in FIG. 13, the first holding part 14 aof the base unit 1 has an inclined surface 4 cthat is inclined with respect to the longitudinal direction so as to apply the force in the height direction applied by the leaf spring 31. The inclined surface 4 cis inclined so as to gradually approach the second holding part 14 bside toward the longitudinal direction.The first engaging part 21 aof the connection unit 2 aincludes an inclined surface 5 ewhich is inclined with respect to the longitudinal direction so as to apply the force in the height direction applied by the leaf spring 31. The inclined surface 5 eis inclined so as to gradually approach the second holding part 14 bside toward the longitudinal direction.Next, a mechanism for reducing the load of the gasket 30 in the PLC as described above will be described. When the connecting unit 2a is supported by the base unit 1, the inclined surface 4c of the first supporting member 14a and the inclined surface 5e of the first engaging member 21a are brought into contact with each other. By pressing the inclined surface 5e against the inclined surface 4c by the force exerted by the leaf spring 31 toward the longitudinal direction, the force exerted by the leaf spring 31 is converted into the force in the height direction directed from the first holding part 14a toward the second holding part 14b. Therefore, even if an external force is applied from the second holding part 14 bto the first holding part 14 a, the external force is counteracted by the force in the height direction converted by the inclined surface 4 cor the inclined surface 5 e. Therefore, since the vibration of the connection unit 2 acan be suppressed, the load on the gasket 30 can be reduced. As a result, the gasket 30 is less easily damaged by twisting, rubbing, or the like, and the waterproof and dust-proofness of the gasket 30 can be obtained.Note that, as shown in FIG. 14, an inclined surface 4 dwhich is inclined so as to gradually approach the first holding part 14 aside toward the longitudinal direction may be formed in the second holding part 14 bof the base unit 1. Further, an inclined surface 5 fwhich is inclined so as to approach the first holding part 14 aside toward the longitudinal direction may be formed in the second engaging part 21 bof the connection unit 1. In the case of the inclined surfaces formed as described above, the force exerted by the leaf spring 31 is converted into the force in the height direction directed from the second holding part 14 bto the first holding part 14 a. Therefore, even if an external force is applied in the direction from the first holding part 14 ato the second holding part 14 b, the external force is counteracted by the force in the height direction transformed by the inclined surface 4 dor the inclined surface 5 f. Therefore, the vibration of the connection unit 2 acan be suppressed, and the load on the gasket 30 can be reduced. Therefore, the gasket 30 is less easily damaged, and the water-proofness and the dust-proofness of the gasket 30 can be obtained.Embodiment 3In Embodiment 1, an example in which the guide parts 15 are formed in a hollow parallelepiped shape extending from the other end of the front cover 12 ato the longitudinal direction has been described. In contrast, in Embodiment 3, an example in which guide parts 17 having a shape of a hollow trapezoid are formed will be described. In particular, since the guide members 17 are different from those of Embodiment 1 in that they have inclined surfaces 4e inclined with respect to the longitudinal direction, the difference will be described below.As shown in FIG. 15, the front cover 12 aincludes a plurality of guide parts 17 formed to extend from the other end of the front cover 12 ato the longitudinal direction. Each of the guide parts 17 has a shape of a hollow trapezoid that is open on both sides in the height direction. The plurality of guide members 17 are provided such that when the connection unit 2a is supported by the base unit 1, two of the guide members 17 are brought into proximity with the module case 22.FIG. 16 is a perspective view from the back side of the connection unit 2 a. The module case 22 has notches 22 cformed on both sides in the lateral direction of the module case 22 so as to extend along the plurality of guide parts 17. Each notch 22c is shaped like a notch after a trapezoidal column is removed. By the notches 22 cconfigured as described above, a portion of the module case 22 is placed between the second holding part 14 band one of the guide parts 17 of the base unit 1 when the connection unit 2 ais held by the base unit 1.FIG. 17 is a plan view of the PLC. As shown in FIG. 17, the plurality of guide parts 17 each have the inclined surfaces 4 einclined such that the width in the lateral direction becomes gradually narrower toward the longitudinal direction.FIG. 18 is an enlarged plan view of the adjacent portions of the guide member 17 and the module case 22 when an external force is applied in the lateral direction. Portions of the module case 22 sandwiched between the second holding part 14 band the guide part 17 are brought into contact with the second holding part 14 band the guide part 17 when an external force in a lateral direction is applied. As described above, by bringing portions of the module case 22 into contact with the second holding part 14 band the guide part 17, further displacement of the connection unit 2 acan be restricted. That is, since the vibration of the connection unit 2 acan be suppressed, the load on the gasket 30 can be reduced. As a result, the gasket 30 is less easily damaged by twisting, rubbing, or the like, and the waterproof and dust-proofness of the gasket 30 can be obtained.Further, since the guide part 17 has the inclined surfaces 4 e, it is possible to increase the contact area between the connection unit 2 aand the guide part 17 when an external force in a lateral direction is applied such that the connection unit 2 aapproaches the inclined surfaces 4 eand thus the connection unit 2 acomes in contact with the guide part 17. Therefore, for example, even if an external force that causes lateral displacement of the connection unit 2 athat cannot be restricted when the contact area between the connection unit 2 aand the guide part 17 is small is applied to the module case 22, the large contact area realized by the inclined surfaces 4 eprovided on the guide part 17 makes it possible to restrict the displacement of the connection unit 2 ain the lateral direction.By the shape of the guide members 17 having the shape of a hollow trapezoid, the volume of the module case 22 occupied by the notches 22 cmay be reduced compared to the case where the guide members 17 have the shape of a hollow rectangular parallelepiped. Therefore, the volume of the module case 22 can be increased. Therefore, a plurality of electronic components built in the module case 22 can be placed separately from each other, and thus heat dissipation of the electronic components can be improved.Note that the guide part 17 need not have the shape of a hollow rectangular parallelepiped as long as it is provided with the inclined surfaces 4 e, but may also have the shape of a triangular prism.Note that the inclined surfaces 4 eof the guide part 17 may be inclined such that the width in the height direction gradually becomes narrower toward the longitudinal direction. Even with such guide members 17, the volume of the module case 22 occupied by the notches 22 cmay be reduced as compared to the case where the guide members 17 have the shape of a hollow rectangular parallelepiped. Therefore, the volume of the module case can be increased.Embodiment 4In Embodiment 1, an example has been described in which a portion of the module case 22 is placed between the second holding part 14 band one of the guide parts 15 of the base unit 1 when the connection unit 2 ais held by the base unit 1. In Embodiment 4, an example in which protrusions are provided between the guide parts 15 and the module case 22 will now be described. In particular, since the guide parts 15 and the module case 22 are different from those of Embodiment 1 in that they have protrusions extending in the lateral direction, these differences will now be described.As shown in FIG. 19, the front cover 12 aincludes the plurality of guide parts 15 formed to extend from the other end of the front cover 12 ato the longitudinal direction. The guide parts 15 each have a shape of a hollow rectangular parallelepiped that is open to both sides in the height direction. The guide parts 15 have protrusions 15 athat protrude in the lateral direction. The protrusions 15a are formed on rear sides of the surfaces of the guide members 15 in the longitudinal direction. Two of the protrusions 15 aare formed on each surface, and are arranged in parallel to the height direction. That is, four of the protrusions 15 aare formed for each of the guide parts 15.As shown in FIG. 20, the connecting unit 2 aincludes the module case 22. protrusions 22 dprotruding in the lateral direction are provided on front surfaces of the module case 22, which surfaces are brought into proximity to the guide parts 15 when the connecting unit 2 ais supported by the base unit 1. The protrusions 22 dare formed on both sides of the module case 22 in the lateral direction, on either side of one.FIG. 21 is an enlarged plan view of the adjacent parts of the guide parts 15 and the module case 22 when an external force is applied in the lateral direction. When an external force in a lateral direction is applied to the connection unit 2 a, a portion of the module case 22 sandwiched between the second holding part 14 band the guide part 15 is brought into contact with the second holding part 14 b, and one of the protrusions 22 dof the module case 22 is brought into contact with the guide part 15. By the protrusions 22 dformed as described above, the displacement of the connection unit 2 ain the lateral direction can be restricted earlier than when the protrusions 22 dare not formed. Therefore, the load on the gasket 30 can be further reduced. As a result, the gasket 30 is less easily damaged by twisting, rubbing, or the like, and the water-proofness and dust-proofness can be obtained.In addition, when an external force in the opposite direction to the above-described direction is applied to the connection unit 2 a, a portion of the module case 22 sandwiched between the second holding part 14 band the guide part 15 is brought into contact with the second holding part 14 b, and portions of the module case 22 are brought into contact with the protrusions 15 aof the module case 22. By the projections 15 aformed as described above, the displacement of the connection unit 2 ain the lateral direction can be restricted earlier than when the projections 15 aare not formed. That is, since the vibration of the connection unit 2 acan be suppressed, the load on the gasket 30 can be further reduced. As a result, the gasket 30 is less easily damaged by twisting, rubbing, or the like, and the water-proofness and dust-proofness can be obtained.A protrusion may be provided on the surface of the second holding part 14 badjacent to the module case 22.The protrusions 15 aof the guide part 15 may be formed on the front side, and the protrusions 22 dof the module case 22 may be formed on the rear side.When the protrusions 22 dare not formed on the module case 22, the protrusions 15 aand the protrusions 22 dmay be formed on the guide part 15. Similarly, when the protrusions 15 aare not formed on the guide part 15, the protrusions 15 aand the protrusions 22 dmay be formed on the module case 22.In Embodiments 1 to 4, examples have been described in which various configurations and combinations thereof are shown for the pair of holding parts 14, the guide parts 15 and 17, and the engagement mechanism 21, but the embodiments are not limited thereto. For example, in order to obtain the waterproof and the dust-proofness of the gasket 30, it is possible to employ a different combination of the configuration described in the embodiments. Specifically, the pair of holding parts 14 and the engagement mechanism 21 may be provided with inclined surfaces inclined in mutually different directions, such as the lateral direction and the height direction. Moreover, inclined surfaces may be provided in one of the pair of holding parts 14 and the engagement mechanism 21. Further, the pair of holding parts 14 may be formed to have a plurality of inclined surfaces inclined in different directions. Further, the guide members 15 and 17 may be used in combination with the pair of holding members 14 and the engaging mechanism 21 described in another embodiment.List of reference characters1 Base unit 10 Substrate 11 Base-side connector 12 Base housing 13 Opening 14 Pair of holding parts 14 aFirst holding part 14 bSecond holding part 15 Guide part 15 a 2 Module unit 17 Guide part 2 aConnecting unit 20 Module-side connector 21 Engagement mechanism 21 aFirst engagement part 21 bSecond engagement part 22 Module housing 22 aFitting protrusion 22 b Kerbe 22 c 22 c 22 d 30 Packing 31 Leaf spring 4 a 4 b 4 c 4 d 4 e 5 a 5 b Schrägfläche 5 c 5 d 5 e Schrägfläche 5 f

Claims

A programmable logic controller comprising: a base unit (1); and a plurality of modular units (2) connected to the base unit (1), the base unit (1) comprising: a substrate (10) having a plurality of base-side connectors (11) electrically connecting the plurality of modular units (2) via the plurality of base-side connectors (11); a base housing (12) having an opening (13) through which one of the plurality of base-side connectors (11) is exposed and housing the substrate (10); and at least one holding part (14a, 14b) for holding a connection unit (2a) constituting one of the plurality of modular units (2), the connection unit (2a) comprising: a module-side connector (20) for being connected to one of the plurality of base-side connectors (11); an engaging mechanism (21) for detachably engaging with the at least one holding part (14a, 14b) of the base unit (1); and a module case (22) having a fitting protrusion (22a) formed to fit with the base case (12) and to engage the module-side connector (20), wherein the programmable logic controller further includes: an elastic member (31) for applying a force in a first direction, which is a direction in which the connecting unit (2a) moves away from the base unit (1), for pressing the engaging mechanism (21) of the connecting unit (2a) against the at least one holding part (14a, 14b) of the base unit (1); and a sealing member (30) for sealing a gap between the base housing (12) and the fitting protrusion (22a) of the module housing (22), and wherein the at least one holding part (14a, 14b) is provided in plural and forms a pair (14), and the pair of holding parts (14) has at least one first inclined surface (4a) inclined with respect to the first direction such that the force applied by the elastic member (31) acts in a second direction intersecting the first direction.The programmable logic controller according to claim 1, wherein the sealing member (30) is provided on a side surface of the fitting protrusion (22a), the side surface being parallel to the first direction, or on an opposite surface of the base case (12), the opposite surface facing the side surface of the fitting protrusion (22a).The programmable logic controller according to claim 1 or 2, wherein the second direction is parallel to a direction from the one holding part (14a) to the other holding part (14b) of the pair of holding parts (14), and the at least one inclined surface (4a) is inclined so as to gradually approach a side of the other holding part (14b) toward the first direction.The programmable logic controller according to claim 1 or 2, wherein the second direction is a direction perpendicular to both the first direction and a direction from one holding part (14a) to the other holding part (14b) of the pair of holding parts (14), and wherein the at least one inclined surface (4a-4e) is provided in plurality such that the engagement mechanism (21) of the connection unit (2a) is sandwiched from both sides and a distance between the inclined surfaces (4a-4e) gradually becomes narrower toward the first direction, whereby the force applied from the elastic member (31) acts in the second direction.The programmable logic controller according to claim 1 or 2, wherein the engagement mechanism (21) includes at least one inclined surface (5a) inclined with respect to the first direction such that the force applied by the elastic member (31) acts in the second direction intersecting the first direction.The programmable logic controller according to claim 5, wherein the second direction is parallel to a direction from one holding part (14a) to the other holding part (14b) of the pair of holding parts (14), and one of the at least one inclined surface (5a) is inclined so as to gradually approach a side of the other holding part (14b) from one side of the one holding part (14a) toward the first direction.The programmable logic controller according to claim 5, wherein the second direction is a direction perpendicular to both the first direction and a direction from one holding part (14a) to the other holding part (14b) of the pair of holding parts (14), and the engagement mechanism (21) includes a plurality of inclined surfaces (5a-5f) inclined such that its width in the second direction becomes gradually narrower toward the first direction.The programmable logic controller according to claim 1 or 2, wherein the module case (22) has a plurality of inclined surfaces sandwiching the engagement mechanism (21) from both sides, and a distance between the inclined surfaces gradually increases toward the first direction.The programmable logic controller according to claim 1 or 2, wherein the base unit (1) further includes a plurality of guide parts (17) formed to extend in the first direction, wherein the module case (22) has grooves (22b, 22c) formed to face along the plurality of guide parts (17), and wherein at least two of the plurality of guide parts (17) are brought into proximity to the module case (22) when the connection unit (2a) is supported by the base unit (1).The programmable logic controller of claim 9, wherein at least one of a surface of each guide member (17) adjacent to the module housing (22) and a surface of the module housing (22) adjacent to each guide member (17) includes a protrusion (22d).The programmable logic controller according to claim 9, wherein each of the guide members (17) has at least one inclined surface (4a-4e) inclined such that its width gradually becomes narrower toward the first direction.A base unit (1) of a programmable logic controller equipped with the base unit (1) and a plurality of modular units (2) to be connected to the base unit (1), the base unit (1) including: a substrate (10) having a plurality of base-side connectors (11) electrically connecting the plurality of modular units (2) via the plurality of base-side connectors (11); a base housing (12) having openings (13) through which the plurality of base-side connectors (11) are exposed and housing the substrate (10); at least one holding part (14a, 14b) for holding a connection unit (2a) constituting one of the plurality of modular units (2) by being engaged with an engagement mechanism (21) of the connection unit (2a); an elastic member (31) for applying a force in a first direction, which is a direction in which the link unit (2a) moves away from the base unit (1), to press the engagement mechanism (21) of the link unit (2a) against the at least one holding part (14a, 14b) of the base unit (1); and a sealing member (30) for sealing a gap between a fitting protrusion (22a) of the module case (22) of the connection unit (2a) and the base case (12), wherein the fitting protrusion (22a) is formed to fit around the module-side connector (20) of the connection unit (2a) to be connected to one of the plurality of base-side connectors (11), wherein the at least one holding part (14a, 14b) is provided in plural and forms a pair (14), and the pair of holding parts (14) has at least one inclined surface (4a) inclined with respect to the first direction such that the force applied from the elastic member (31) acts in a second direction intersecting the first direction.A programmable logic controller module unit (2), the programmable logic controller being provided with: a base unit (1) having a substrate (10) with a plurality of base-side connectors (11), a base housing (12) having an opening (13) through which one of the plurality of base-side connectors (11) is exposed and which houses the substrate (10), and at least one holding part (14a, 14b) for holding another unit; and the module unit (2) to be connected to the base unit (1), the module unit (2) including: a module-side connector (20) for being attached to a base-side connector (11) of the base unit (1); an engaging mechanism (21) for detachably engaging with the at least one holding part (14a, 14b) of the base unit (1); a module case (22) having a fitting protrusion (22a) formed to fit with the base case (12) and to engage the module-side connector (20); an elastic member (31) for applying a force in a first direction, which is a direction in which the module unit (2) moves away from the base unit (1), to press the engagement mechanism (21) of the module unit (2) against the at least one holding part (14a, 14b) of the base unit (1); and a sealing member (30) for sealing a gap between the base housing (12) and the fitting protrusion (22a) of the module housing (22), wherein the at least one holding part (14a, 14b) is provided in plural and forms a pair (14), and the pair of holding parts (14) has at least one inclined surface (4a) inclined with respect to the first direction such that the force applied by the elastic member (31) acts in a second direction intersecting the first direction.

Images