Electromagnetic contactor

Abstract

The invention provides an electromagnetic contactor which can have an operation display part protection function and a charging part protection function at the same time. An opening (9) provided in the housing (4) is covered by a connector (25) connected to the housing. In addition, terminal parts (6a-6d, 7a-7d) arranged on the power supply side and the load side of the housing (2B) are covered by a flat-plate-shaped protective cover (26) connected with the connecting piece (25).

Description

Technical Field

[0001] The present invention relates to an electromagnetic contactor provided with a protective cover for protecting a terminal portion in a detachable manner. Background Art

[0002] The top cover of the electromagnetic contactor is provided with the primary and secondary terminal parts, and an opening is formed between the primary and secondary terminal parts. A contact support of a contact mechanism fixed to the movable iron core of the electromagnet unit is arranged inside the housing of the electromagnetic contactor, and the action convex part of the contact support protrudes from the opening part or sinks into the opening part, thereby functioning as an action display part.

[0003] The electromagnetic contactor of patent document 1 is constructed such that a first protective cover (action display protective cover) covering the opening of the action display part is detachably installed on the top cover, and has an action display part protection function such as preventing dust from invading the contact mechanism inside the shell through the opening, or preventing erroneous operation of the action display part of the contact support of the contact mechanism.

[0004] In addition, the electromagnetic contactor of Patent Document 2 has a second protective cover (charging unit protective cover) covering the primary and secondary terminal parts detachably installed around the opening of the top cover, and has a charging unit protection function to prevent electric shock to the primary and secondary terminal parts.

[0005] Patent Document 1: Japanese Patent Application Laid-Open No. 5-290705

[0006] Patent Document 2: Japanese Patent Application Publication No. 2000-113791 Summary of the invention

[0007] Technical problem to be solved by the invention

[0008] However, as shown in Patent Documents 1 and 2, the conventional electromagnetic contactor is provided with one of the first protective cover and the second protective cover, and cannot have both the operation display unit protection function and the charging unit protection function.

[0009] An object of the present invention is to provide an electromagnetic contactor which can simultaneously have an operation display unit (ie, an operation indication unit) protection function and a charging unit protection function.

[0010] Technical means for solving technical problems

[0011] In order to achieve the above-mentioned purpose, an electromagnetic contactor of one embodiment of the present invention is constructed as follows: a contact mechanism and an electromagnet device are arranged inside a shell, a terminal portion and an opening portion on a power supply side and a load side are formed in the shell, an action display portion is arranged on a contact support of the contact mechanism, and protrudes from or sinks into the inside of the opening portion due to the on / off drive of the electromagnet device, a connecting member covering the opening portion is detachably installed in the shell, a connecting member opening portion is formed on the connecting member through which the action display portion can be visually viewed from the outside, and a cover connecting portion is provided for connecting the protective cover in the form of a detachable flat-plate-shaped protective cover, and the protective cover covers the terminal portions on the power supply side and the load side.

[0012] Effects of the Invention

[0013] The electromagnetic contactor of the present invention connects the protective cover covering the terminal part on the power supply side and the load side to the shell via a connecting piece, and can simultaneously have an action display part protection function of preventing dust from invading the contact mechanism inside the shell from the opening, or preventing erroneous operation of the action display part of the contact mechanism, and a charging part protection function of preventing electric shock to the terminal part on the primary side and the secondary side. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 This is a developed perspective view showing a state in which a coupling member and a protective cover are coupled to the electromagnetic contactor in the first embodiment of the present invention.

[0015] Figure 2 This is a diagram of the electromagnetic contactor as seen from the front.

[0016] Figure 3 yes Figure 2 AA line view.

[0017] Figure 4 yes Figure 2 BB line view.

[0018] Figure 5 It is a perspective view showing the shape of the connecting tool used in the first embodiment.

[0019] Figure 6 This is a cross-sectional view of the main parts showing a state in which a part of the coupling tool is inserted into the cover opening of the electromagnetic contactor in the first embodiment.

[0020] Figure 7 This is a cross-sectional view of a main part showing a state in which a connecting member is connected to an arc-extinguishing cover of an electromagnetic contactor in the first embodiment.

[0021] Figure 8 This is a perspective view showing a state in which a protective cover is connected to the electromagnetic contactor via a connecting member in the first embodiment.

[0022] Fig. 9 This is a developed perspective view showing a state in which a coupling member and a protective cover are coupled to an electromagnetic contactor in a second embodiment of the present invention.

[0023] Fig.10 It is a perspective view showing the shape of a connecting tool used in the second embodiment.

[0024] Fig.11 This is a perspective view showing a state in which a protective cover is connected to the electromagnetic contactor via a connecting member in the second embodiment.

[0025] Fig.12 This is a cross-sectional view showing a state in which a protection cover is connected to a housing of an electromagnetic contactor via a connecting member in the second embodiment.

[0026] Description of Reference Numerals

[0027] 1 Electromagnetic contactor

[0028] 2A First rack

[0029] 2B Second rack

[0030] 3 Mounting plate

[0031] 4 Arc extinguishing cover

[0032] 5a, 5b anti-rotation groove

[0033] 6a, 6b, 6c, 6d Power supply side terminals

[0034] 7a, 7b, 7c, 7d Load side terminals

[0035] 8 Coil terminal section

[0036] 9 Cover opening

[0037] 10 Contact mechanism

[0038] 12 Solenoid unit

[0039] 13 Fixed core

[0040] 13a Pole contact surface

[0041] 13b Central protrusion

[0042] 14 Movable iron core

[0043] 14a Pole contact surface

[0044] 15. Solenoid coil

[0045] 16 Return spring

[0046] 18a Fixed contact on power supply side

[0047] 18b Load side fixed contact

[0048] 18a1, 18b1 fixed contacts

[0049] 19 Contact support

[0050] 21 Winding rack

[0051] 22 Winding

[0052] 20a, 20b movable contacts

[0053] 20 Movable contact

[0054] 23 Action display unit

[0055] 24a, 24b: rack protrusion

[0056] 24a1, 24b1 first engaging recess

[0057] 25, 40 connectors

[0058] 26, 41 protective cover

[0059] 27 Connector body

[0060] 28 Connector opening

[0061] 29a, 29b Foot

[0062] 30a, 30b foot engagement portion

[0063] 31a, 31b: rotation preventing projections

[0064] 32 Engagement claw

[0065] 33 Raised part

[0066] 34a, 34b snap-fit ​​mechanism

[0067] 35a, 35b fitting protrusions

[0068] 36 raised hole

[0069] 37a, 37b fitting hole

[0070] 38a~38d Electrical test insertion hole

[0071] 42 Engagement release section

[0072] 43 Engagement release insertion hole. DETAILED DESCRIPTION

[0073] Next, the embodiments of the present invention are described with reference to the accompanying drawings. In the following description of the drawings, the same or similar parts are given the same or similar reference numerals. However, it should be noted that the drawings are schematic, and the relationship between thickness and plane size, the ratio of thickness of each layer, etc. are different from the actual structure. Therefore, the specific thickness and size should be judged with reference to the following description. In addition, the drawings also include parts with different relationship and ratio of each other's size.

[0074] In addition, the embodiments shown below are examples of devices and methods for realizing the technical concept of the present invention, and the technical concept of the present invention does not limit the material, shape, structure, configuration, etc. of the components to the methods described below. Various changes can be made to the technical concept of the present invention within the technical scope of the invention.

[0075] In addition, terms indicating directions such as “upper”, “lower”, “front”, “rear”, “left”, and “right” described in the following description are used with reference to directions in the drawings.

[0076] [First embodiment]

[0077] like Figure 1 As shown, in the electromagnetic contactor 1 of the first embodiment of the present invention, the first frame 2A and the second frame 2B formed of a synthetic resin having electrical insulation properties constitute a housing. In addition, the housing of the present invention corresponds to the second frame 2B and the arc extinguishing cover.

[0078] The first frame 2A is a square cylindrical body with a bottom, and a mounting plate portion 3 is formed at the four corners of the rear end. The second frame 2B is a square cylindrical body with an open rear end, and an arc extinguishing cover 4 covering the contact mechanism 10 described later is detachably mounted at the front end. Figure 2 As shown, on the upper side of the second frame 2B, power supply side terminals 6a, 6b, 6c, 6d and a coil terminal portion 8 are formed. On the lower side of the second frame 2B, load side terminals 7a, 7b, 7c, 7d are formed. The electromagnetic contactor 1 is arranged in a switchboard or the like mounted on a wall by fixing bolts penetrating the mounting plate portion 3, but this is not shown here.

[0079] Figure 3The internal structure of the electromagnetic contactor 1 is shown, which includes: a contact mechanism 10 installed in the second frame 2B; and an electromagnet unit 12 installed in the first frame 2A, which is an electromagnet device that drives the contact mechanism 10 to turn on / off. The electromagnet unit 12 includes: a fixed iron core 13 arranged on the bottom side of the first frame 2A; a movable iron core 14 arranged with a pole contact surface 14a facing the pole contact surface 13a of the fixed iron core 13; an electromagnetic coil 15 arranged to be inserted through the central protrusion 13b of the fixed iron core 13; and a return spring 16 arranged between the front side of the electromagnetic coil 15 and the movable iron core 14. The electromagnetic coil 15 has a winding frame 21 and a winding 22 wound on the cylindrical portion of the winding frame 21.

[0080] The contact mechanism 10 includes: a plurality of power-side fixed contacts 18a and load-side fixed contacts 18b fixed to the second frame 2B and arranged in a row in the left-right direction; a contact support 19 installed inside the second frame 2B so as to be movable in the front-to-back direction; and a plurality of movable contacts 20 supported by the contact support 19, the plurality of movable contacts 20 being movable in the front-to-back direction so that the movable contacts 20a, 20b can contact and separate from the fixed contacts 18a1 of the plurality of power-side fixed contacts 18a and the fixed contacts 18b1 of the plurality of load-side fixed contacts 18b.

[0081] like Figure 2 As shown, the arc extinguishing cover 4 mounted on the second frame 2B is formed with a cover opening 9 having a quadrilateral shape. An operation display portion 23 and a pair of frame protrusions 24a, 24b are arranged inside the cover opening 9. A pair of rotation prevention grooves 5a, 5b extending linearly downward in parallel to each other are formed at the lower edge of the opening 9. In addition, the opening of the present invention corresponds to the cover opening 9.

[0082] The action display unit 23 is as follows Figure 4 As shown in FIG. 1 , the contact support 19 is integrally formed on the upper part of the contact support 19, and protrudes from or sinks into the opening 9 due to the front-to-back movement of the contact support 19 during the opening and closing operation of the electromagnetic contactor 1, and functions as an operation display portion of the electromagnetic contactor 1. In addition, the operation display portion 23 during the disconnection operation of the electromagnetic contactor 1 moves to a position that does not extend to the outside of the opening 9 (toward the front side of the arc extinguishing cover 4). A pair of frame protrusions 24a, 24b are as shown in FIG. Figure 4 As shown, the housing 2B is formed integrally with the second housing 2B at a distance in the left-right direction relative to the action display unit 23. The front end of one housing protrusion 24a is bent to the right to form a first engaging recess 24a1. The front end of the other housing protrusion 24b is bent to the left to form a first engaging recess 24b1. In addition, the housing engaging portion of the present invention corresponds to the first engaging recess 24a1 and the first engaging recess 24b1.

[0083] Figure 1 Reference numeral 25 is a connecting member connected to the opening portion 9 of the electromagnetic contactor 1. Figure 1 Reference numeral 26 denotes a protective cover that covers the power supply side terminals 6a, 6b, 6c, 6d, the load side terminals 7a, 7b, 7c, 7d, and the coupling member 25 from the front side.

[0084] The connecting member 25 is formed of a synthetic resin having electrical insulation properties, such as Figure 5 As shown in (a) and (b) of FIG. 1 , the connector includes a quadrilateral plate-shaped connector body 27 and a connector opening 28 formed in the thickness direction of the connector body 27 and penetrating the connector body 27 in the approximate center. On one surface of the connector body 27, as shown in FIG. Figure 5 As shown in (a), there are formed: a pair of legs 29a, 29b extending in parallel from two opposite sides so as to surround the connector opening 28; and leg engaging portions 30a, 30b protruding in an L shape from the front ends of the pair of legs 29a, 29b in directions opposite to each other. In addition, on one surface of the connector body 27, a rotation preventing protrusion 31a, 31b is formed on one of two other opposite sides different from the two sides on which the pair of legs 29a, 29b are formed, and an engaging claw portion 32 is formed on the other side of the two sides. In addition, on the periphery of the connector opening 28 on the other surface of the connector body 27, as shown in FIG. Figure 5 As shown in (b), the boss 33 protrudes and forms engaging protrusions 35a and 35b constituting a pair of locking mechanisms 34a and 34b.

[0085] The protective cover 26 is a rectangular plate formed of a transparent synthetic resin having electrical insulation properties, such as Figure 1 As shown, in the central part in the long side direction (length direction), a protrusion hole 36 is formed for the protrusion 33 of the connecting member 25 to be inserted therein, and a pair of engaging holes 37a, 37b constituting a pair of snap-fit ​​mechanisms 34a, 34b are formed. In addition, on the upper side of the protective cover 26, four test holes 38a to 38d are formed.

[0086] Next, refer to Figure 6 to Figure 8 , the process of connecting the connecting member 25 to the arc extinguishing cover 4 of the electromagnetic contactor 1 and connecting the protective cover 26 to the connecting member 25 is described. Figure 6 and Figure 7 The portions indicated by oblique lines are the leg engaging portions 30 a and 30 b , the anti-rotation protrusions 31 a and 31 b , and the engaging claw portion 32 of the coupling 25 .

[0087] First, a pair of legs 29a, 29b and leg engaging portions 30a, 30b of the connector 25 are inserted into the opening 9 of the arc extinguishing cover 4. At this time, a part of the anti-rotation protrusions 31a, 31b of the connector 25 enters a part of the anti-rotation grooves 5a, 5b formed on the periphery of the opening 9.

[0088] Then, if Figure 7 As shown, by sliding the connecting piece 25 downward, the leg engaging portions 30a, 30b engage with the first engaging recesses 24a1, 24b1 of the frame protrusions 24a, 24b, the entire area of ​​the anti-rotation protrusions 31a, 31b of the connecting piece 25 enters the anti-rotation grooves 5a, 5b, and the engaging claw portion 32 engages with the periphery of the cover opening portion 9. In this state, the connecting piece 25 is connected to the arc extinguishing cover 4.

[0089] Then, if Figure 8 As shown, the boss 33 of the connector 25 is inserted into the boss hole 36 of the protective cover 26. Then, the claws of the fitting protrusions 35a and 35b formed on the connector 25 are engaged with the peripheries of the fitting holes 37a and 37b of the protective cover 26, and the boss 33 is inserted into the boss hole 36, thereby connecting the protective cover 26 and the connector 25.

[0090] According to the first embodiment, since the protective cover 26 covers the power side terminals 6a, 6b, 6c, 6d, the load side terminals 7a, 7b, 7c, 7d and the entire cover opening 9 from the front side, it can simultaneously have an action display part protection function of preventing dust from intruding into the contact mechanism 10 from the cover opening 9 or preventing erroneous operation of the action display part 23 of the contact mechanism 10, and a charging part protection function that can reliably prevent the user from getting an electric shock to the power side terminals 6a, 6b, 6c, 6d and the load side terminals 7a, 7b, 7c, 7d.

[0091] In addition, by fitting the protrusion 33 of the connecting member 25 into the protrusion hole 36 of the protective cover 26, the fitting protrusions 35a, 35b of the connecting member 25 and the fitting hole portions 37a, 37b of the protective cover 26 are snapped together, so that the protective cover 26 and the connecting member 25 can be firmly connected. Moreover, with respect to the arc extinguishing cover 4 connected to the connecting member 25, since the rotation preventing protrusions 31a, 31b are embedded in the rotation preventing grooves 5a, 5b of the arc extinguishing cover 4, even if the rotation force in the surface direction acts on the protective cover 26, the rotation preventing grooves 5a, 5b of the arc extinguishing cover 4 also bear the rotation force. Therefore, the connection strength of the protective cover 26 with respect to the electromagnetic contactor 1 when the rotation force acts on the protective cover 26 can be improved.

[0092] In addition, when the connecting member 25 is slid downward while covering the cover opening 9, the leg engaging portions 30a and 30b of the connecting member 25 engage with the first engaging recesses 24a1 and 24b1 of the frame protrusions 24a and 24b inside the cover opening 9, and the engaging claw portion 32 of the connecting member 25 engages with the peripheral edge of the cover opening 9, thereby making it easy to install the connecting member 25 on the arc extinguishing cover 4. Moreover, by releasing the engagement of the engaging claw portion 32 from the peripheral edge of the cover opening 9 and sliding upward to release the engagement of the leg engaging portions 30a and 30b and the first engaging recesses 24a1 and 24b1, the connecting member 25 can also be easily removed (disassembled). In this way, the connecting member 25 of the present embodiment can be easily attached and detached relative to the cover opening 9 of the arc extinguishing cover 4.

[0093] Furthermore, when measuring the voltage of the power-side terminals 6a, 6b, 6c, and 6d, with the protective cover 26 installed on the electromagnetic contactor 1, a multimeter can be inserted from the test insertion holes 38a to 38d into the power-side terminals 6a, 6b, 6c, and 6d to measure the voltage, thereby making it easy to perform inspection operations on the timing control circuit.

[0094] Furthermore, since the protective cover 26 is formed of a transparent synthetic resin and the connector 25 is provided with a connector opening 28, the movement of the action display portion 23 that functions as an action display portion and protrudes and sinks relative to the cover opening 9 can be easily confirmed visually through the connector opening 28 and the protective cover 26.

[0095] [Second Embodiment]

[0096] then, Fig. 9 A coupling member 40 and a protective cover 41 of a second embodiment mounted on the electromagnetic contactor 1 of the present invention are shown. The same components as those of the coupling member 25 and the protective cover 26 of the first embodiment are given the same reference numerals and their description is omitted.

[0097] In the connecting member 40 of this embodiment, Fig.10 As shown in (a) and (b), a plate-shaped engagement release portion 42 is formed, which protrudes in a stepped manner from one side of the quadrangular plate-shaped connecting piece body 27 where the engagement claw portion 32 is formed in the same direction as the boss portion 33 and the fitting protrusions 35a, 35b.

[0098] In addition, in the protective cover 41 of this embodiment, as Fig. 9 As shown, the disengagement insertion hole 43 is formed between the test insertion holes 38a to 38d formed on one side in the longitudinal direction and the pair of fitting holes 37a and 37b and the boss hole 36 formed on the other side in the longitudinal direction.

[0099] Next, refer to Fig.11 and Fig.12 The flow of connecting the connecting member 40 to the arc extinguishing cover 4 of the electromagnetic contactor 1 and connecting the protective cover 41 to the connecting member 40 will be described.

[0100] The connector 40 is similar to the connector 25 of the first embodiment. The pair of legs 29a, 29b and the leg engaging portions 30a, 30b are inserted into the cover opening 9 of the arc extinguishing cover 4, and a part of the rotation preventing protrusions 31a, 31b enter a part of the rotation preventing grooves 5a, 5b formed on the periphery of the cover opening 9. Then, the connector 25 is slid downward to engage the leg engaging portions 30a, 30b with the first engaging recesses 24a1, 24b1 of the frame protrusions 24a, 24b, and the rotation preventing protrusions 31a, 31b of the connector 25 enter the rotation preventing grooves 5a, 5b, thereby connecting the connector 40 to the arc extinguishing cover 4 in a state where the engaging claws 32 are engaged with the periphery of the cover opening 9.

[0101] like Fig.11 As shown in FIG. 1 , the protrusion 33 of the connecting member 40 is inserted into the protrusion hole 36 of the protective cover 41. In addition, the claws of the fitting protrusions 35a and 35b of the connecting member 40 are engaged with the peripheries of the fitting holes 37a and 37b of the protective cover 41, and the protrusion 33 is inserted into the protrusion hole 36, so that the protective cover 41 and the connecting member 40 are connected. At this time, as shown in FIG. Fig.12 As shown, the disengagement portion 42 of the connector 40 is inserted into the disengagement insertion hole 43 of the protective cover 41 from the back side (the side that contacts the connector 40) of the protective cover 41. As a result, the front end side of the disengagement portion 42 contacts the front side of the protective cover 41.

[0102] When external force Fig.12 When the arrow T1 direction (forward) acts on the connecting piece 40 and the protective cover 41 connected to the arc extinguishing cover 4 of the electromagnetic contactor 1, the engagement release portion 42 engaged with the front surface of the protective cover 41 moves forward, so that the engagement of the engagement claw portion 32 with respect to the peripheral edge of the cover opening portion 9 is released, and then the protective cover 41 is moved in the Fig.12 By moving in the direction of arrow T2 (upward), the engagement of the anti-rotation protrusion 31b (31a) of the connecting piece 40 with the anti-rotation groove 5b (5a) of the arc extinguishing cover 4 is released, so that the connecting piece 40 and the protective cover 41 can be removed from the arc extinguishing cover 4.

[0103] Therefore, the second embodiment can obtain the same effects as the first embodiment, and when an external force acts on the protective cover 41 in the front away from the arc extinguishing cover 4, the engagement release portion 42 engaged with the front surface of the protective cover 41 moves forward, and the engagement of the engagement claw portion 32 with respect to the periphery of the cover opening 9 is released. In addition, by moving the protective cover 41 upward, the engagement of the rotation prevention projections 31a and 31b of the connecting member 40 with respect to the rotation prevention grooves 5a and 5b of the arc extinguishing cover 4 is released, and the protective cover 41 and the connecting member 40 can be removed from the cover opening 9 of the arc extinguishing cover 4 at the same time. Therefore, the protective cover 41 and the connecting member 40 can be easily removed from the cover opening 9.

[0104] In addition, in the first and second embodiments, the connection between the connecting member 25 (40) and the protective cover 26 (41) is achieved by interlocking the protrusion 33 and the protrusion hole 36 and by interlocking the snap-fit ​​mechanisms 34a and 34b. However, the present invention is not limited to this connection structure. For example, a connection structure in which connecting holes are formed in the connecting member 25 (40) and the protective cover 26 (41) and push rivets are interlocked with these connecting holes, or a connection structure in which a connecting hole is formed in one of the connecting member 25 (40) and the protective cover 26 (41), a protrusion is provided in the other, and the head of the protrusion extending from the connecting hole is riveted. The same effects as those of the first and second embodiments can be obtained.

Claims

1. An electromagnetic contactor, characterized in that: A contact mechanism and an electromagnet device are arranged inside the housing. The housing is provided with terminals and openings on the power supply side and the load side. The action display part of the contact support provided in the contact mechanism can be protruded from or sunk into the interior of the opening due to the on / off driving of the electromagnet device. A connecting member covering the opening is detachably mounted on the housing. The connector has a connector opening through which the operation display unit can be viewed from the outside, and a cover connecting portion for detachably connecting a flat plate-shaped protective cover that covers the terminals on the power supply side and the load side.

2. The electromagnetic contactor according to claim 1, characterized in that: The connecting member includes: a plate-shaped cover body that closes the opening; a leg engaging portion formed on a pair of legs protruding from one surface of the cover body; and an engaging claw portion formed at a position spaced apart from the pair of legs. When the pair of legs are inserted into the opening and the cover body is slid, the leg engaging portion engages with the housing engaging portion in the opening, and the engaging claw engages with the opening periphery of the opening, thereby detachably attaching the connector to the housing.

3. The electromagnetic contactor according to claim 2, characterized in that: The protective cover is formed with an engagement release insertion hole, The coupling piece is provided with an engagement release portion which can be inserted into the engagement release insertion hole and overlaps with the outer surface of the protection cover. When an external force acts on the protection cover in a direction away from the coupling member, the engagement between the engagement claw portion of the coupling member and the opening peripheral edge of the opening portion can be released via the engagement release portion.

4. The electromagnetic contactor according to any one of claims 1 to 3, characterized in that: The protection cover is provided with an electric test insertion hole at least at a position facing the terminal portion on the power supply side.

5. The electromagnetic contactor according to any one of claims 1 to 3, characterized in that: The protective cover is formed of a transparent material.

6. The electromagnetic contactor according to any one of claims 1 to 3, characterized in that: The protection cover is connected to the connecting member via a cover connecting portion.

7. The electromagnetic contactor according to claim 6, characterized in that: The cover coupling portion includes: a boss formed on one of the coupling member and the protective cover; and a boss hole formed on the other of the coupling member and the protective cover and into which the boss is inserted.

8. The electromagnetic contactor according to claim 7, characterized in that: The cover connecting portion is a snap-fit ​​mechanism that also includes an interlocking protrusion and an interlocking hole, wherein the interlocking protrusion is formed in one of the connecting piece and the protective cover, and the interlocking hole is formed in the other of the connecting piece and the protective cover for the interlocking protrusion to be embedded therein.

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