A new structure of battery cover plate lower plastic

Abstract

The application discloses a new-structure battery cover plate lower plastic, which comprises a lower plastic body, a battery cover plate arranged on the lower plastic body, wire connection pole columns arranged at both ends of the upper surface of the battery cover plate, an explosion-proof valve plate arranged at the middle part of the inner side of the battery cover plate, and a pressure relief through hole arranged at the middle part of the inner side of the lower plastic body, wherein an easily-broken rib assembly is fixed to the inner wall of the pressure relief through hole. The lower plastic body comprises a first rubber plate, a second rubber plate and a third rubber plate. The first rubber plate, the second rubber plate, the third rubber plate and the elastic rubber body are arranged, the device is designed in a split type, the device is convenient to replace and maintain after damage in a certain section, the length size required can be adjusted according to actual needs, the first friction surface and the second friction surface are arranged, the device is designed in different roughness, leakage can be carried out when air tightness detection is carried out after the sealing ring is missed, and the outflow of the defective products of the missed sealing ring is reduced.

Description

Technical Field

[0001] The present invention specifically relates to a new structure of plastic under a battery cover. Background Art

[0002] Lithium batteries are a type of battery that uses lithium metal or lithium alloy as the positive and negative electrode materials and a non-aqueous electrolyte solution. Due to the very active chemical properties of lithium metal, the processing, storage, and use of lithium metal have very high environmental requirements. With the development of science and technology, lithium batteries have now become mainstream. The plastic plate under the lithium battery cover is usually a key component in the battery module design. It is mainly used to provide structural support, protect battery cells, isolate heat sources or current, and help improve the safety and durability of the battery. The plastic under the battery cover is generally made by injection molding.

[0003] The existing plastic under the battery cover is mostly an integrated structure, which is not convenient for segmented maintenance in the later stage. The size is not easy to adjust after the one-piece injection molding. Due to thermal expansion and contraction or mold manufacturing factors, the dimensional accuracy of the lower plastic is poor, affecting the precise installation of the lower plastic and the battery cover. In addition, during the later airtightness test, due to the close fit between the terminal post and the lower plastic, if the sealing ring is forgotten on the terminal post, the airtightness test cannot detect it, resulting in the outflow of defective products with missing sealing rings and poor use effect. For this reason, we propose a new structure for the plastic under the battery cover. Summary of the Invention

[0004] The purpose of the present invention is to provide a new structure of the lower plastic of the battery cover to solve the problem proposed in the above background technology that the lower plastic is an integrated structure, which is inconvenient to maintain or adjust the size of the lower section in the later stage. In addition, the lower plastic is tightly matched with the terminal post, which affects the detection of missing sealing rings.

[0005] To achieve the above objectives, the present invention provides the following technical solutions: a new structure of plastic under the battery cover, comprising:

[0006] A lower plastic body, wherein a battery cover is provided on the lower plastic body, and terminal poles are provided at both ends of the upper surface of the battery cover;

[0007] The explosion-proof valve is located in the middle of the inner side of the battery cover;

[0008] A pressure relief hole is provided in the middle of the inner side of the lower plastic body, and a fragile rib assembly is fixed to the inner side wall of the pressure relief hole;

[0009] The lower plastic body includes a first plastic plate, a second plastic plate and a third plastic plate, and the second plastic plate and the third plastic plate are detachably mounted on both ends of the first plastic plate to correspond to the terminal poles;

[0010] The elastic colloid is arranged between the first rubber plate and the second rubber plate to elastically adjust the position of the first rubber plate.

[0011] Preferably, the lower plastic body is provided with a mounting hole at the inner end thereof, which is matched with the wiring pole, and the mounting hole is provided with a first friction surface and a second friction surface at the inner side thereof, which are distributed along the circumference of the mounting hole.

[0012] Preferably, the first rubber plate is provided with a connecting head at the outer end thereof, and the lower end of the side wall of the connecting head is fixed with a sliding plate; the second rubber plate is provided with a connecting sliding groove at the end surface thereof, which is matched with the connecting head, and the inner wall of the connecting sliding groove is provided with a clamping structure matched with the connecting head.

[0013] Preferably, the clamping structure comprises an elastic clamping strip and a clamping groove, and the elastic clamping strip is fixed on the upper end of the inner wall of the connecting sliding groove, and the side wall of the connecting head is provided with the clamping groove matched with the elastic clamping strip.

[0014] Preferably, the elastic clamping strip is arc-shaped, and the clamping groove and the elastic clamping strip are provided with a plurality of clamping grooves and elastic clamping strips.

[0015] Preferably, the elastic rubber body comprises a rubber bottom plate, a first elastic block and a second elastic block, the rubber bottom plate is fixed in the connecting sliding groove, and the upper surface of the rubber bottom plate is provided with the first elastic block and the second elastic block at the two ends thereof, respectively, and the first elastic block and the second elastic block are staggered to stretch and contract the adjacent long edges of the first rubber plate and the second rubber plate.

[0016] Preferably, the second rubber plate and the third rubber plate are equal in shape and size, and the lower surface of the second rubber plate is fixed with a convex plate.

[0017] Preferably, the rib assembly comprises a connecting rib, a broken hole and a pressure bearing surface, the connecting rib is fixed on the inner wall of the pressure relief through hole, the connecting rib is provided with the broken hole at the two ends thereof at the inner side thereof, which is used for tearing when pressure relief, and the lower surface of the connecting rib is provided with the pressure bearing surface which is recessed inwardly to bear pressure.

[0018] Preferably, the battery cover plate is provided with a liquid injection hole at the inner side thereof, and the lower plastic body is provided with a communication hole corresponding to the liquid injection hole.

[0019] Preferably, the upper surface of the battery cover plate is provided with a raised surrounding plate, the inner side of the surrounding plate is provided with an upper plastic plate, and the upper plastic plate is in contact with the wiring pole.

[0020] Compared with the prior art, the present application has the following beneficial effects:

[0021] (1) The patent sets up the first rubber plate, the second rubber plate, the third rubber plate and the elastic rubber body, avoids the lower plastic to be the integral structure, causes the lower plastic to be damaged in a certain section, is not convenient to replace alone, influences the maintenance convenience, and the length of the integral lower plastic is not convenient to adjust after injection molding, influences the installation, the device is convenient to replace and maintain after the damage of a certain section through the split design, and the length size required can be adjusted according to actual needs, so that the installation convenience effect is improved, and after installation, the elastic force of the elastic rubber body can make the communication hole and the injection hole close, the gap between the two is sealed, so that the leakage does not occur when injecting later, and the injection safety effect is improved.

[0022] (2) By setting the first friction surface and the second friction surface, the wiring pole is not easy to find the missing sealing ring during the later air tightness test after being assembled into the mounting hole, the device is designed with different roughness, and the leakage can be reduced when the air tightness test is carried out after the missing sealing ring, so that the flow of defective products of the missing sealing ring is reduced, and the practicability of the device is increased.

[0023] (3) By setting the connecting rib, the damaged hole and the pressure bearing surface, the connecting strip inside the pressure relief hole is not easy to break, so that when the lithium battery shell needs to be relieved due to accident, the gas is blocked, which affects the flow of gas to the outside, the device can automatically break when relieving pressure to reduce the blockage of gas, improve the smoothness of pressure relief, and increase the use effect of the device. DRAWINGS

[0024] Figure 1 It is a structural diagram of the application;

[0025] Figure 2 It is a lower plastic body structure diagram of the application;

[0026] Figure 3 It is a rib assembly structure diagram of the application;

[0027] Figure 4 It is a first rubber plate and second rubber plate connection structure diagram of the application;

[0028] Figure 5 It is an elastic rubber body structure diagram of the application;

[0029] Figure 6 It is a connecting rib section structure diagram of the application;

[0030] Figure 7 It is a first friction surface structure diagram of the application;

[0031] Figure 8 It is a wiring pole and lower plastic cooperation diagram of the existing;

[0032] In the figure: 1, the lower plastic body; 101, the first rubber plate; 102, the second rubber plate; 103, the third rubber plate; 104, the convex plate; 105, the mounting hole; 106, the elastic clamping strip; 107, the clamping groove; 109, the connecting head; 110, the sliding plate; 112, the connecting sliding groove; 2, the battery cover plate; 3, the wiring pole; 4, the upper plastic plate; 5, the explosion-proof valve piece; 6, the liquid injection hole; 7, the rib assembly; 701, the connecting rib; 702, the breakage hole; 703, the pressure bearing surface; 8, the elastic rubber body; 801, the rubber bottom plate; 802, the first elastic block; 803, the second elastic block; 901, the first friction surface; 902, the second friction surface; 12, the communication hole; 13, the sealing ring; 14, the contact area. DETAILED DESCRIPTION

[0033] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work fall within the scope of protection of the present application.

[0034] Please refer to Figures 1-8 The present application provides a technical solution: a new structure battery cover plate lower plastic, comprising:

[0035] The lower plastic body 1 is provided with the battery cover plate 2 on the upper surface of the lower plastic body 1, and the wiring poles 3 are arranged at both ends of the upper surface of the battery cover plate 2.

[0036] The explosion-proof valve piece 5 is arranged in the middle of the inner side of the battery cover plate 2.

[0037] The pressure relief through hole is arranged in the middle of the inner side of the lower plastic body 1, and the rib assembly 7 which is easy to break is fixed to the inner side wall of the pressure relief through hole, so that when it is necessary to relieve pressure outwardly, the rib assembly 7 is broken to reduce the obstruction to the pressure relief gas and improve the smoothness of the pressure relief.

[0038] Among them, the lower plastic body 1 includes the first rubber plate 101, the second rubber plate 102 and the third rubber plate 103, the second rubber plate 102 and the third rubber plate 103 are detachably installed at both ends of the first rubber plate 101 to correspond to the wiring poles 3, so that the later replacement and maintenance of the damaged section are facilitated by the split lower plastic body 1, and the inconvenience of overall replacement is reduced.

[0039] The elastic colloid 8 is arranged between the first glue plate 101 and the second glue plate 102 to elastically adjust the position of the first glue plate 101, facilitate the later adjustment of the length of the lower plastic colloid 1, reduce the length of the integrated lower plastic colloid during injection molding, and facilitate the connection and assembly of the lower plastic colloid and the battery cover plate 2 after deformation caused by thermal expansion and cold contraction. The device can well adjust the length and improve the convenience of later assembly. After installation, the first glue plate 101 can be elastically supported to make the communication hole 12 on the first glue plate 101 close to the liquid injection hole 6, reduce the gap between the two, and facilitate the later liquid injection.

[0040] Preferably, the lower plastic colloid 1 is provided with a mounting hole 105 at the inner end, which is matched with the wiring pole 3. The inner side of the mounting hole 105 includes a first friction surface 901 and a second friction surface 902. The first friction surface 901 and the second friction surface 902 are distributed along the circumference of the mounting hole 105, and the roughness of the first friction surface 901 and the second friction surface 902 is different.

[0041] The existing Figure 8 As shown, the wiring pole 3 is tightly attached to the contact area 14 of the lower plastic colloid 1, so that the entire cover plate appears "false sealing". During the later helium detection for air tightness, if the sealing ring 13 is forgotten to be installed on the outer surface of the wiring pole 3, the tightly attached contact area 14 will cause the undetected leakage of the sealing ring 13, resulting in the outflow of defective products.

[0042] The device uses different roughness to make the upper surface of the wiring pole 3 and the contact area 14 of the lower surface of the lower plastic colloid 1 not tightly attached. If the sealing ring 13 is missed, the air tightness detection in the later process can detect it, avoiding the outflow of defective products.

[0043] Preferably, the first glue plate 101 is provided with a connecting head 109 protruding outward at both ends, and the connecting head 109 is fixed with a sliding plate 110 at the lower end of the side wall. The second glue plate 102 is provided with a connecting sliding groove 112 matched with the connecting head 109 at one end surface, and the inner wall of the connecting sliding groove 112 is provided with a clamping structure connected with the connecting head 109, so as to facilitate the quick connection of the first glue plate 101 and the second glue plate 102.

[0044] Preferably, the clamping structure includes an elastic clamping strip 106 and a clamping groove 107. The elastic clamping strip 106 is fixed on the upper end of the inner wall of the connecting sliding groove 112, and the connecting head 109 is provided with a clamping groove 107 matched with the elastic clamping strip 106 at the upper end of the side wall, so as to facilitate the quick clamping and matching.

[0045] Preferably, the elastic clamping strip 106 is arc-shaped, and the clamping groove 107 and the elastic clamping strip 106 are provided with a plurality of clamping grooves and elastic clamping strips, respectively, so as to facilitate the later adjustment of the gap between the first glue plate 101 and the second glue plate 102, and further adjust the length of the lower plastic colloid 1 as a whole.

[0046] Preferably, the elastic colloid 8 comprises a rubber bottom plate 801, a first elastic block 802 and a second elastic block 803, the rubber bottom plate 801 is fixed to the inner side of the connecting groove 112, so as to support the first rubber plate 101 and the battery cover plate 2 to be close to each other by the elastic force of the rubber bottom plate 801, so as to reduce the gap between the communication hole 12 and the liquid injection hole 6, thereby avoiding the injection liquid from flowing out of the larger gap during the injection, and the upper surface of the rubber bottom plate 801 is provided with the first elastic block 802 and the second elastic block 803 at both ends, respectively, so as to adjust the length of the lower plastic body 1 to be shortened after elastic stretching, and the first elastic block 802 and the second elastic block 803 are staggered to stretch and contract the adjacent long edges of the first rubber plate 101 and the second rubber plate 102.

[0047] Preferably, the second rubber plate 102 and the third rubber plate 103 are equal in shape and size, and the lower surface of the second rubber plate 102 is fixed with a convex plate 104.

[0048] Preferably, the rib assembly 7 comprises a connecting rib 701, a broken hole 702 and a pressure bearing surface 703, the connecting rib 701 is fixed to the inner wall of the pressure relief through hole, so as to improve the strength of the lower plastic body 1 by the connecting rib 701, the broken hole 702 is provided at both ends of the inner side of the connecting rib 701, so as to tear when relieving pressure, and the lower surface of the connecting rib 701 has the pressure bearing surface 703 which is recessed inward to bear pressure, so as to be better impacted by the gas to break and fracture when relieving pressure, thereby reducing the influence on the flow of the pressure relief gas when relieving pressure.

[0049] Preferably, the battery cover plate 2 is provided with a liquid injection hole 6 in the inner side, and the lower plastic body 1 is provided with a communication hole 12 corresponding to the liquid injection hole 6 in the inner side, so as to facilitate the injection of liquid into the battery shell in the later stage.

[0050] Preferably, the upper surface of the battery cover plate 2 is provided with a raised coaming, the coaming is provided with an upper plastic plate 4 in the inner side, and the upper plastic plate 4 is in contact with the wiring pole 3.

[0051] The working principle and use process of the present application: in use, the first rubber plate 101, the second rubber plate 102 and the third rubber plate 103 are respectively injection molded to form, then the elastic rubber body 8 is placed inside the connecting chute 112, both are fixed by glue, the connecting head 109 at one end of the first rubber plate 101 is inserted into the inside of the connecting chute 112, at this time the elastic clamping strip 106 and the clamping groove 107 are engaged to quickly connect the first rubber plate 101 and the second rubber plate 102, and the third rubber plate 103 can be connected with the first rubber plate 101 to form the lower plastic body 1, after the lower plastic body 1 is damaged, it can be maintained separately in later period, the thickness of the sliding plate 110 is less than the thickness of the guiding groove opened in the side wall of the connecting chute 112, the sliding plate 110 can move up and down inside the guiding groove, when the lower plastic body 1 is assembled to the lower surface of the battery cover plate 2, through the elastic force of the first elastic block 802 and the second elastic block 803, the length of the lower plastic body 1 can be adjusted according to the actual situation, so as to reduce the poor installation effect caused by the inaccurate size due to thermal expansion and cold shrinkage during injection molding, at the same time, the second rubber plate 102 and the third rubber plate 103 are elastically supported on the first rubber plate 101 through the rubber bottom plate 801 to push the communication hole 12 inside the first rubber plate 101 to correspond with the liquid injection hole 6, avoiding the lower plastic body being integral type, causing the communication hole 12 and the liquid injection hole 6 to be far away from each other, affecting the later liquid injection effect, after being installed on the lithium battery shell in later period, when pressure relief occurs, the gas inside the lithium battery shell will impact the connecting rib 701, the pressure bearing surface 703 on the lower surface of the connecting rib 701 will be under great pressure, then the both ends will be broken through the broken hole 702, and then the gas will quickly impact the explosion-proof valve plate 5 from the pressure relief through hole to relieve pressure to the outside.

[0052] Although embodiments of the present application have been shown and described, it is to be understood that various changes, modifications, substitutions and alterations can be made to the embodiments without departing from the principles and spirit of the present application, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A new structure battery cover plate under plastic, characterized in that, The utility model relates to a battery cover plate (2) is provided with wiring pole (3) on the upper surface both ends of the battery cover plate (2), and the wiring pole (3) is used for connecting the battery cover plate (2) and the battery, and the battery cover plate (2) is used for preventing the battery from being damaged by the external force. The utility model relates to a battery cover plate (2) is provided with wiring pole (3) on the upper surface both ends of the battery cover plate (2), and the wiring pole (3) is used for connecting the battery cover plate (2) and the battery, and the battery cover plate (2) is used for preventing the battery from being damaged by the external force. The utility model relates to a battery cover plate (2) is provided with wiring pole (3) on the upper surface both ends of the battery cover plate (2), and the wiring pole (3) is used for connecting the battery cover plate (2) and the battery, and the battery cover plate (2) is used for preventing the battery from being damaged by the external force. The utility model relates to a battery cover plate (2) is provided with wiring pole (3) on the upper surface both ends of the battery cover plate (2), and the wiring pole (3) is used for connecting the battery cover plate (2) and the battery, and the battery cover plate (2) is used for preventing the battery from being damaged by the external force. The utility model relates to a battery cover plate (2) is provided with wiring pole (3) on the upper surface both ends of the battery cover plate (2), and the wiring pole (3) is used for connecting the battery cover plate (2) and the battery, and the battery cover plate (2) is used for preventing the battery from being damaged by the external force. The utility model relates to a battery cover plate (2) is provided with wiring pole (3) on the upper surface both ends of the battery cover plate (2), and the wiring pole (3) is used for connecting the battery cover plate (2) and the battery, and the battery cover plate (2) is used for preventing the battery from being damaged by the external force. The utility model relates to a battery cover plate (2) is provided with wiring pole (3) on the upper surface both ends of the battery cover plate (2), and the wiring pole (3) is used for connecting the battery cover plate (2) and the battery, and the battery cover plate (2) is used for preventing the battery from being damaged by the external force. The utility model relates to a battery cover plate (2) is provided with wiring pole (3) on the upper surface both ends of the battery cover plate (2), and the wiring pole (3) is used for connecting the battery cover plate (2) and the battery, and the battery cover plate (2) is used for preventing the battery from being damaged by the external force. The utility model relates to a battery cover plate (2) is provided with wiring pole (3) on the upper surface both ends of the battery cover plate (2), and the wiring pole (3) is used for connecting the battery cover plate (2) and the battery, and the battery cover plate (2) is used for preventing the battery from being damaged by the external force.

2. The new structure battery cover plate lower plastic according to claim 1, characterized in that: The utility model relates to a battery cover plate (2) is provided with wiring pole (3) on the upper surface both ends of the battery cover plate (2), and the wiring pole (3) is used for connecting the battery cover plate (2) and the battery, and the battery cover plate (2) is used for preventing the battery from being damaged by the external force.

3. A new structure of battery cover plate lower plastic according to claim 2, characterized in that: The utility model relates to a battery cover plate (2) is provided with wiring pole (3) on the upper surface both ends of the battery cover plate (2), and the wiring pole (3) is used for connecting the battery cover plate (2) and the battery, and the battery cover plate (2) is used for preventing the battery from being damaged by the external force.

4. The new structure battery cover plate lower plastic of claim 3, characterized in that: The utility model relates to a battery cover plate (2) is provided with wiring pole (3) on the upper surface both ends of the battery cover plate (2), and the wiring pole (3) is used for connecting the battery cover plate (2) and the battery, and the battery cover plate (2) is used for preventing the battery from being damaged by the external force.

5. The new structure battery cover plate lower plastic of claim 1, wherein: The utility model relates to a battery cover plate (2) is provided with wiring pole (3) on the upper surface both ends of the battery cover plate (2), and the wiring pole (3) is used for connecting the battery cover plate (2) and the battery, and the battery cover plate (2) is used for preventing the battery from being damaged by the external force. The utility model relates to a battery cover plate (2) is provided with wiring pole (3) on the upper surface both ends of the battery cover plate (2), and the wiring pole (3) is used for connecting the battery cover plate (2) and the battery, and the battery cover plate (2) is used for preventing the battery from being damaged by the external force. The utility model relates to a battery cover plate (2) is provided with wiring pole (3) on the upper surface both ends of the battery cover plate (2), and the wiring pole (3) is used for connecting the battery cover plate (2) and the battery, and the battery cover plate (2) is used for preventing the battery from being damaged by the external force. The utility model relates to a battery cover plate (2) is provided with wiring pole (3) on the upper surface both ends of the battery cover plate (2), and the wiring pole (3) is used for connecting the battery cover plate (2) and the battery, and the battery cover plate (2) is used for preventing the battery from being damaged by the external force. The utility model relates to a battery cover plate (2) is provided with wiring pole (3) on the upper surface both ends of the battery cover plate (2), and the wiring pole (3) is used for connecting the battery cover plate (2) and the battery, and the battery cover plate (2) is used for preventing the battery from being damaged by the external force. The utility model relates to a battery cover plate (2) is provided with wiring pole (3) on the upper surface both ends of the battery cover plate (2), and the wiring pole (3) is used for connecting the battery cover plate (2) and the battery, and the battery cover plate (2) is used for preventing the battery from being damaged by the external force. The utility model relates to a battery cover plate (2) is provided with wiring pole (3) on the upper surface both ends of the battery cover plate (2), and the wiring pole (3) is used for connecting the battery cover plate (2) and the battery, and the battery cover plate (2) is used for preventing the battery from being damaged by the external force. The utility model relates to a battery cover plate (2) is provided with wiring pole (3) on the upper surface both ends of the battery cover plate (2), and the wiring pole (3) is used for connecting the battery cover plate (2) and the battery, and the battery cover plate (2) is used for preventing the battery from being damaged by the external force. The utility model relates to a battery cover plate (2) is provided with wiring pole (3) on the upper surface both ends of the battery cover plate (2), and the wiring pole (3) is used for connecting the battery cover plate (2) and the battery, and the battery cover plate (2) is used for preventing the battery from being damaged by the external force. The utility model relates to a battery cover plate (2) is provided with wiring pole (3) on the upper surface both ends of the battery cover plate (2), and the wiring pole (3) is used for connecting the battery cover plate (2) and the battery, and the battery cover plate (2) is used for preventing the battery from being damaged by the external force. The utility model relates to a battery cover plate (2) is provided with wiring pole (3) on the upper surface both ends of the battery cover plate (2), and the wiring pole (3) is used for connecting the battery cover plate (2) and the battery, and the battery cover plate (2) is used for preventing the battery from being damaged by the external force. The utility model relates to a battery cover plate (2) is provided with wiring pole (3) on the upper surface both ends of the battery cover plate (2), and the wiring pole (3) is used for connecting the battery cover plate (2) and the battery, and the battery cover plate (2) is used for preventing the battery from being damaged by the external force. The utility model relates to a battery cover plate (2) is provided with wiring pole (3) on the upper surface both ends of the battery cover plate (2), and the wiring pole (3) is used for connecting the battery cover plate (2) and the battery, and the battery cover plate (2) is used for preventing the battery from being damaged by the external force. The utility model relates to a battery cover plate (2) is provided with wiring pole (3) on the upper surface both ends of the battery cover plate (2), and the wiring pole (3) is used for connecting the battery cover plate (2) and the battery, and the battery cover plate (2) is used for preventing the battery from being damaged by the external force. The utility model relates to a battery cover plate (2) is provided with wiring pole (3) 6. The new structure battery cover plate lower plastic of claim 1, wherein: The battery cover plate (2) is internally provided with a liquid injection hole (6), and the lower plastic body (1) is internally provided with a communication hole (12) corresponding to the liquid injection hole (6).

7. The new structure battery cover plate lower plastic of claim 1, wherein: The upper surface of the battery cover plate (2) is provided with a raised surrounding plate, the inner side of the surrounding plate is provided with an upper plastic plate (4), and the upper plastic plate (4) is in contact with the wiring pole (3).

Images