Lead-acid battery

Abstract

Lead-acid battery, in particular large-capacity battery, with a housing (2) and a plurality of electrode plates (6, 7) arranged in the housing (2), wherein positive and negative electrode plates (6, 7) are provided, which alternate with a separator (8) in between, wherein the housing (2) has a base body (3) open on one side and a cover (5) closing the open side (4) of the base body (3), wherein the positive electrode plates (6) on the one hand and the negative electrode plates (7) on the other hand are each electrically connected to each other by means of a terminal bridge (12, 13), wherein each terminal bridge (12, 13) carries a terminal pole (14, 15), wherein the terminal poles (14, 15) project through a respective through-opening (16) in the cover (5), characterized in thatthat the connecting pole (15) of the positive electrode plates (6) is longitudinally displaceable from the associated through-hole (16) in relation to the cover (5).

Description

The invention relates to a lead-acid battery, in particular a so-called GroE battery, with a housing and a plurality of electrode plates arranged in the housing, wherein positive and negative electrode plates are provided which alternate with a separator in between, wherein the housing has a base body open on one side and a lid closing the open side of the base body, wherein the positive electrode plates on the one hand and the negative electrode plates on the other hand are each electrically connected to each other by means of a pole bridge, wherein each pole bridge carries at least one terminal pole, wherein the terminal poles protrude through a respective opening in the lid. Blue-acid batteries in general, and those in the special design known as so-called GroE batteries in particular, are well known from the prior art, which is why a separate printed reference is not required here. A typical accumulator has a casing and a number of electrode plates housed within the casing. Furthermore, the casing contains an electrolyte which, under normal operating conditions, circulates around the electrode plates. In the case of a lead-acid accumulator, sulfuric acid is the most commonly used electrolyte. The battery housing has a base body that is open on one side. This open side allows for the installation of the electrode plates during manufacturing. In the final assembled state, the open side of the housing is closed by a lid. This lid forms a fluid-tight seal with the base body, specifically against electrolytes. The system features positive electrode plates on one side and negative electrode plates on the other. The positive and negative electrode plates are arranged alternately, with a separator between each pair of adjacent electrode plates to prevent short circuits. Both the positive and negative electrode plates are electrically connected to each other by means of a pole bridge. Thus, there is a first pole bridge and a second pole bridge, with the first connecting the positive electrode plates and the second connecting the negative electrode plates. Each pole bridge has at least one terminal. Therefore, there is a positive terminal, the so-called plus terminal, and a negative terminal, the so-called minus terminal. Both terminals protrude through openings in the housing lid. This allows for external electrical contact between the terminals. The electrode plates of the lead-acid battery each have a grid and an active material, the active material being supported or held by the grid. The active material, i.e., the material involved in the chemical reaction, is lead dioxide (PbO2) in the case of the positive electrode and lead (Pb) in the case of the negative electrode. The electrolyte is preferably dilute sulfuric acid (H2SO4). During discharge of the battery, lead, lead dioxide, and sulfuric acid react to form lead sulfate (PbSO4) and water (H2O). During charging, the processes are reversed, meaning lead sulfate and water react again to form lead, lead dioxide, and sulfuric acid. Unlike other battery types, the electrolyte participates in this reaction. An undesired side reaction occurs when water (H2O) decomposes into oxygen (O2) and hydrogen (H2). As already mentioned, separators are provided between the electrode plates to prevent contact between the differently polarized plates and thus a short circuit. At the same time, however, the separators must allow the ions involved in the reaction to migrate. They must therefore be electrically insulating on the one hand and ion-permeable on the other. Furthermore, they should be acid- and oxidation-resistant. Suitable materials for lead-acid batteries include, for example, polyethylene (PE), polyvinyl chloride (PVC), or phenolic resins. Different lead-acid battery designs are distinguished depending on the structure of the positive and negative electrode plates. In the GroE design (acronym for large surface plates, close installation) according to DIN 40 738, the positive electrode plate consists of a pure lead plate with a lamellar surface structure. The positive active material PbO2 is then formed on the plates through the so-called formation process. The negative electrode plates are cast grids made of lead or a lead alloy. Other cell types include, for example, OPzS cells (stationary armor plate special separation) and OCSM cells (stationary copper (Cu) expanded metal), in which the positive plates are tubular plates whose core grids are cast from a lead-antimony alloy. Lead-coated copper expanded metal grids (OCSM) are also used for industrial negative plate grids. The GroE and OPzS battery types, with standard cast or die-cast grids, are generally designed as sealed batteries. In sealed batteries, the electrolyte is liquid and freely mobile, meaning it is not confined. As mentioned earlier, oxygen and hydrogen gas are produced at the electrodes through the decomposition of water. This gas must be vented from the battery casing via plugs. Since water is also lost through decomposition, water must be added occasionally. Unlike sealed batteries, there are also sealed batteries in which the electrolyte is contained as a gel or in a fleece. The oxygen produced does not escape but diffuses to the negative plate, where it reacts to form water and lead sulfate. This suppresses the formation of hydrogen. An example of a sealed design is the OPzV cell (Loaded Fixed Armor Plate). The advantages of GroE batteries include their high corrosion resistance and therefore long service life. They are particularly suitable for short, high-current discharges and thus for emergency power supply in power plants, for example. In the event of a malfunction, GroE batteries safeguard, for example, the control systems of a power plant and supply cooling systems via emergency power circuits. A disadvantage, particularly with large-capacity (GroE) batteries, is that the positive electrode plates grow over time due to oxidation. Consequently, under normal operating conditions, the positive electrode plates expand vertically, becoming larger over time. This means they eventually occupy more space within the battery casing. This is addressed in the design by making the positive electrode plates shorter vertically than the negative electrode plates. The negative electrode plates also protrude downwards relative to the positive electrode plates. This space can then be used for the growth of the positive electrode plates under normal operating conditions. The positive electrode plates grow progressively with continued operation. Over time, the space provided for their growth may become insufficient. This can lead to the positive electrode plates bearing against the bottom of the battery housing and being pushed upwards as they continue to grow. Because the terminal, which is connected to the positive electrode plates, is fixed to the battery housing cover to ensure electrolyte tightness, cracks can form in the cover, resulting in electrolyte leaks. In the worst-case scenario, the terminal, which is rigidly connected to the cover, can even push it upwards to such an extent that it bursts. Starting from the above, the invention is based on the objective of further developing a lead-acid battery, in particular a GroE battery, in such a way that a long service life is ensured while maintaining operational reliability and, in particular, electrolyte leaks due to growth of the positive electrode plates are avoided. To solve this problem, the invention proposes a lead-acid accumulator of the type mentioned above, which is characterized in that the terminal pole of the positive electrode plates is longitudinally displaceable from the associated through-hole in relation to the lid. According to the invention, a so-called pole feedthrough is provided, which allows the connecting pole to be moved vertically relative to the cover. The cover is therefore not force-transmittingly coupled to the connecting pole, so that pole movements occurring as a result of electrode plate growth are not hindered relative to the cover and can thus occur. Force acting on the cover due to electrode plate growth is therefore avoided. The connection pole according to the invention is longitudinally displaceable by the associated through-opening in the lid. This allows the connection pole to move relative to the lid. Therefore, if the electrically connected connection pole moves upwards as the positive electrode plate grows sufficiently, no force is exerted on the lid, since the connection pole can move freely in the vertical direction relative to the lid. This measure according to the invention significantly extends the service life of a generic lead-acid battery, in particular a GroE battery. Operating periods of 20 years, preferably 25 years, and even more preferably 30 years or more are made possible, which in particular allows the use of GroE batteries for emergency power supply in sensitive areas, for example in the emergency power supply of nuclear power plants, with increased safety. The design according to the invention thus achieves an extended service life while simultaneously increasing operational safety. According to a further feature of the invention, the terminal is fluid-sealed from the lid. This prevents unwanted leakage or escape of electrolyte through the contact area between the terminal and the lid, thus ensuring safe operation of the lead-acid battery. Consequently, the design ensures both fluid tightness and the relative adjustability of the terminal relative to the lid. According to a further feature of the invention, it is provided that the connecting pole protrudes through the through-opening with the intermediate arrangement of a ring body surrounding the connecting pole. According to this particularly preferred embodiment, a ring body is provided for a fluid-tight seal between the terminal pole and the cover. This ring body surrounds the terminal pole and is inserted into the through-opening provided by the cover. The terminal pole thus extends through the through-opening, with the ring body surrounding the terminal pole interposed. The ring body ensures, on the one hand, a seal between the terminal pole and the cover, and on the other hand, by acting as a guide, it guarantees the relative movement between the terminal pole and the cover. According to a further feature of the invention, the ring body is arranged in a form-fitting manner on the lid. This form-fitting ensures a secure position of the ring body on the lid. Furthermore, it allows for easy assembly. Additionally, disassembly is permitted, particularly in the case of repairs, by releasing the form-fitting connection between the ring body and the lid. The form-fitting arrangement of the ring body on the lid results in a virtually one-piece design. The ring body is thus secured in position relative to the lid, while surrounding the associated terminal pole with longitudinal movement. The terminal pole can therefore move vertically relative to the ring body and thus also relative to the lid. This possible linear movement of the terminal pole allows, as previously described, for the positive electrode plate to expand without the risk of electrolyte leakage. According to a further feature of the invention, it is proposed that, in the fully assembled state, the ring body rests on the top of the lid with a circumferential ring section and engages the underside of the lid with a locking tab. This design ensures the previously described positive locking between the ring body and the lid in the fully assembled state. The design of the locking tabs allows for exceptionally simple assembly: the ring body is inserted into the corresponding opening in the lid until the locking tabs spring out radially and engage the inside of the lid with the provided locking hooks. In the fully assembled state, the ring body is thus locked to the lid by clamping against it with both the ring section and the locking tabs. According to a further feature of the invention, the ring body is provided with a first seal on the side facing the through-opening. By means of this first seal, the ring body is sealed against the through-opening, i.e., against the cover. According to a further feature of the invention, the ring body is provided with a second seal on the terminal side. This seal thus provides a seal between the ring body on the one hand and the terminal on the other. The combination of the two seals ensures a complete seal between the connection pole and the cover, i.e., the opening through which the connection pole passes. Since the terminal is positioned within the through-hole via an interposed ring body, two seals are provided: a first seal between the cover and the ring body, and a second seal between the ring body and the terminal. This sealing system results in a complete electrolyte seal. Furthermore, because the terminal is allowed longitudinal movement relative to the ring body, the sealing system functions as intended even if the terminal shifts vertically due to expansion of the electrode plate. According to a further feature of the invention, the ring body and a seal are made of plastic. The plastic material forming the seal is preferably injection-molded onto the ring body. Even more advantageous is the use of two seals that are injection-molded onto the ring body and made of the same material. This results in a two-component plastic component consisting of the ring body on one side and the injection-molded seals on the other. Such a two-component design offers the advantage of simplified assembly and disassembly. Furthermore, it allows for simple manufacturing with minimal tolerances. According to a further feature of the invention, the terminal pole is provided to have a plastic cap. This cap is preferably injection-molded onto the terminal pole. The plastic cap of the terminal improves the sealing effect of the aforementioned sealing system. The second seal, i.e., the seal between the ring body and the terminal, does not rest directly against the terminal, but rather is interposed by the cap supported by the terminal. Thus, a seal is created between the second seal on the one hand and the cap supported by the terminal on the other. The two plastic materials of the seal and cap are in direct contact, which enables a better seal. In particular, leaks caused by sulfuric acid creeping along the outer terminal are prevented. As has been shown, despite the aforementioned sealing system consisting of a first and second seal, a 100% seal, particularly between the terminal and the ring body, cannot be achieved. This is because the electrolyte is sulfuric acid-based, and sulfuric acid has a very high tendency to creep. Over time, the sulfuric acid therefore creeps between the seal and the terminal and leaks out at the top of the cap. This leads to discoloration, especially of the terminal, due to corrosion. This should preferably be avoided, which is achieved with the plastic cap preferably supported by the terminal. The plastic cap is preferably designed as a plastic coating by overmolding or molding onto the terminal.This plastic cap has such a height-related extension that the plastic casing provides an additional seal in the contact area between the terminal pole and the second seal of the ring body. According to a further feature of the invention, the terminal pole has an insert made of an electrically conductive material, accessible from its end face. This insert serves to electrically connect the terminal pole to a terminal contact, for example, a terminal contact provided by an electrical cable. The insert provides a threaded bore for the positionally secure placement of a terminal contact in the terminal pole. In the final assembly state, a corresponding screw engages in this bore, thereby detachably coupling the terminal pole to the terminal contact. According to a further feature of the invention, the insert is made of copper or a copper alloy. This results in increased electrical conductivity and simultaneously minimizes the internal resistance of the pole design. According to a further feature of the invention, the cap has an opening. The threaded bore of the insert is accessible from the outside through this opening. Thus, despite the cap, unrestricted and intended access to the threaded bore provided by the insert is ensured. To ensure even better electrolyte sealing, the terminal is equipped with a groove on its outer surface. Several such grooves can be provided along the vertical axis of the terminal, spaced apart from each other. These grooves create a labyrinthine guide around the circumference of the terminal. This labyrinthine guide serves two purposes. Firstly, it increases the creepage distance for the sulfuric acid between the terminal and the cap, and secondly, it creates a better connection between the terminal (or its material) and the plastic casing forming the cap. In its intended use, the terminal pole is equipped at its end face with a connection element, for example a terminal contact, which is screwed to the copper insert provided by the terminal pole. In this intended use, direct access to the terminal pole, for example for carrying out an electrical measurement, is no longer possible, since the terminal pole is completely enclosed by a plastic sheath. Therefore, according to a particularly preferred embodiment, the plastic sheath of the terminal pole may have a gap, in the form of an opening, through which a measuring instrument can be connected to the terminal pole if necessary. According to a further feature of the invention, the connecting pole is provided with a coating on its outer surface. Such a coating can, in particular, be an adhesion promoter that serves to improve the bond and thus also the seal between the connecting pole on the one hand and the plastic sheathing on the other. According to a further feature of the invention, the outer pole has a foot section that terminates seamlessly with the cap in a radial direction. The grooves providing the labyrinth guide are preferably formed by machining, for example by turning. The head section of the connecting pole is turned down to such an extent that, after the cap is finished, there is a smooth transition to the unmachined base section of the connecting pole. This advantageously avoids a step that could abut the underside of the cover in the event of upward displacement of the connecting pole. The displacement of the connecting pole, as provided for in the invention, is therefore not hindered by the design of the plastic casing forming the cap of the connecting pole. In summary, the embodiment according to the invention provides a pole feedthrough with a terminal pole that is longitudinally displaceable relative to the cover. This allows, in particular, for the positive electrode plate to grow without the risk of electrolyte leakage between the terminal pole and the cover. Preferably, a sealing system is provided that has two seals: a terminal-pole seal and a cover-side seal. These two seals are provided by a ring body that surrounds the terminal pole. For further improvement of the sealing effect, the terminal pole can be equipped with a plastic coating on its head side, which interacts with the seal supported by the ring body.Furthermore, it is preferred to form a labyrinth guide between the terminal pole and the coating, which increases the creepage distance for sulfuric acid and also creates a closer connection between the terminal pole and the plastic sheathing. Further features and advantages of the invention will become apparent from the following description with reference to the figures. Fig. 1 shows a schematic side view of a lead-acid battery according to the invention; Fig. 2 shows a schematic detail view of a terminal bushing according to the invention; Fig. 3 shows a schematic perspective view of a ring body according to the invention; Fig. 4 shows a schematic side view of the ring body according to Fig. 3; Fig. 5 shows a schematic sectional view of the ring body according to Fig. 4 along section line AA; Fig. 6 shows a schematic sectional view of a section of the ring body according to Fig. 5, specifically along section Z; Fig. 7 shows a schematic perspective view of a terminal according to the prior art; Fig. 8 shows a schematic perspective view of a terminal according to the invention; Fig. 9 shows a schematic sectional view of a terminal bushing according to the invention; Fig.Fig. 10 shows a schematic sectional view of a terminal pole according to the invention in a first manufacturing step; Fig. 11 shows a schematic view of the terminal pole according to Fig. 10 in a second manufacturing step; and Fig. 12 shows a schematic view of the terminal pole according to Figs. 10 and 11 in a third and final manufacturing step. Fig. 1 shows a schematic sectional view of an accumulator 1 according to the invention in the form of a GroE accumulator. The accumulator 1 has a housing 2 and a plurality of electrode plates 6 and 7 arranged in the housing 2. Positive electrode plates 6 and negative electrode plates 7 are provided, which alternate with a separator 8 in between. The housing 2 is designed in two parts and has a base body 3 that is open on one side and a cover 5 that closes into the open side 4 of the base body 3. In the fully assembled state, the base body 3 and the cover 5 are fluid-tightly connected to each other. The positive electrode plates 6 and the negative electrode plates 7 are each electrically connected to each other by means of a pole bridge 12 or 13. Each pole bridge 12 or 13 carries a terminal pole 14 or 15, respectively. In the illustrated embodiment according to Fig. 1, the positive electrode plates 6 are electrically contacted to each other by means of the pole bridge 13. The pole bridge 12 connects the negative electrode plates 7 to each other. As can be further seen from the illustration in Fig. 1, the pole bridge 12 of the positive electrode plates 6 carries the terminal pole 15. The pole bridge 13 of the negative electrode plates 7, however, carries the terminal pole 14. For the purpose of external contacting the terminals 14 and 15, corresponding through-holes 16 are formed in the cover 5, through which the terminals 14 and 15 protrude. Fig. 2 illustrates this relationship in detail using terminal 15 as an example. As further shown in Fig. 1, the base body 3 of the housing 2 provides a housing base 9. This base has internal webs 10. The negative electrode plates 7 are supported on these webs 10. The positive electrode plates 6 are shorter in the vertical direction 17 than the negative electrode plates 7. They are therefore suspended freely from the base body 3 of the housing 2 and are not supported against the webs 10. Rather, a gap is left between the respective lower edges of the positive electrode plates 6 and the webs 10. In the intended use of the accumulator 1, oxidation causes the positive electrode plates 6 to grow in the vertical direction 17. The positive electrode plates 6 grow downwards in the vertical direction 17, i.e., towards the ribs 10. The space left between the positive electrode plates 6 and the ribs 10 thus serves to accommodate the increase in size of the electrode plates 6 resulting from this growth. However, if the accumulator 1 operates for a sufficiently long time, the space left between the lower edge of the electrode plates 6 and the ribs 10 may become insufficient to compensate for the increase in size of the positive electrode plates 6 due to growth. This can then lead to the electrode plates 6 bearing against the ribs 10 upon reaching them, causing them to be pushed upwards.To ensure that electrolyte leaks do not occur between the terminal pole 15 and the associated through-hole 16 as a result of such upward pressure of the positive electrode plates 6, the inventive design proposes a pole feedthrough which, while simultaneously ensuring a reliable seal between the terminal pole 15 and the cover 5, allows longitudinal displacement of the terminal pole 15 in relation to the through-hole 16 and thus in relation to the cover 5. A pole feedthrough of the same type is preferably provided for the terminal pole 14. For this purpose, the pole feedthrough according to the invention has a ring body 18, as shown in detail in Figs. 3, 4, 5 to 6. The ring body 18 provides a sleeve element 20. This is equipped on its upper side with a ring part 19 and on its underside carries locking tabs 21 equipped with locking hooks 22, as can be seen in particular from a combined view of Fig. 3 and Fig. 4. The ring body 18 is further equipped with a sealing system comprising two seals, namely a first seal 23 and a second seal 24. In the fully assembled state, the first seal 23 is arranged between the ring body 18 and the cover 5, whereas the second seal 24 seals between the ring body 18 and the terminal 15. The individual seals 23 and 24 are designed as circumferential strips that bear against the sleeve element 20 of the ring body 18, as can be seen particularly from a combined view of Figures 5 and 6. In its fully assembled state, the ring body 18 is positively inserted into the corresponding through-opening 16, as can be seen in Figs. 2 and 9. The ring body 18, with its ring section 19, rests against the top of the cover 5, and the locking hooks 22 provided by the locking tabs 21 engage the underside of the cover 5, a relationship that becomes particularly clear from the detailed view in Fig. 9. In the fully assembled state, the connecting pole 15 protrudes through the ring body 18, thus also protruding through the through-opening 16, with the ring body 18 being intermediately arranged. This relationship is also particularly evident from the illustration in Fig. 9. As can be further seen in the illustration according to Fig. 9, in the fully assembled state the seal 23 lies between the ring body 18 and the cover 5 and the seal 24 lies between the ring body 18 and the terminal 15. This ensures a seal between the terminal 15 and the cover 5, even when the terminal 15 is simultaneously movable upwards in the vertical direction 17. According to a particularly preferred embodiment, the terminal pole 15 is equipped with a sheath that forms a cap 25. In the fully assembled state, this cap 25 rests against the seal 24 provided by the ring body 18, resulting in a further improved seal. The plastic sheath forming the cap 25 is preferably injection-molded onto the terminal pole 15. For electrical contact with the terminal 15, a threaded bore 27 is provided on the end face of the terminal 15. This bore is preferably provided by an insert 26 embedded in the terminal 15, which is made of copper to reduce internal resistance. The cap 25 is equipped with a corresponding opening 28 to allow external access to the threaded bore 27. Fig. 7 shows the design of a terminal 15 according to the prior art. Fig. 8 shows a terminal 15 according to the invention. As can be seen from a comparison of the two figures, the terminal 15 according to the invention, as shown in Fig. 8, is equipped with a cap 25 in the configuration described above. The outer terminal 15 has a base section 31 that terminates seamlessly with the cap 25 in the radial direction. The entire outer surface provided by the outer terminal 15 thus transitions seamlessly from the base section 31 to the head section. To achieve an even better seal against unwanted electrolyte leakage, the outer pole 15 is equipped with a labyrinth guide in the area of ​​the cap 25. This labyrinth guide is formed by a plurality of grooves 29 arranged one above the other in the vertical direction 17, as can be seen in particular in Figs. 9, 11 and 12. To form a terminal pole 15 according to the invention, it is first cast from lead or a lead alloy, e.g., hard lead, and fitted with an insert 26 on its end face, as shown in Fig. 10. Subsequently, in a second step, the head region of the terminal pole 15 is machined by turning, thereby reducing the diameter of the terminal pole 15 in the head region, and simultaneously forming the grooves 29. The head region 90 is then surface-coated with an adhesion promoter 30. In a third step, the cap 25 is formed by overmolding the head area of ​​the terminal 15 with a plastic coating. This plastic coating engages in the grooves 29, ensuring a close bond with the lead material of the terminal 15. Furthermore, the groove design has the advantage of increasing the creepage path for the sulfuric acid, which tends to creep, thus minimizing any potential leakage. Reference sign 1 Accumulator 2 Housing 3 Base body 4 Open side 5 Cover 6 Positive electrode plate 7 Negative electrode plate 8 Separator 9 Housing base 10 Bridge 11 Volume chamber 12 Terminal bridge 13 Terminal bridge 14 Terminal post 15 Terminal post 16 Through opening 17 Height direction 18 Ring body 19 Ring part 20 Sleeve element 21 Locking tab 22 Locking hook 23 First seal 24 Second seal 25 Cap 26 Insert 27 Threaded hole 28 Opening 29 Groove 30 Coating 31 Foot section

Claims

Lead-acid battery, in particular large-capacity battery, with a housing (2) and a plurality of electrode plates (6, 7) arranged in the housing (2), wherein positive and negative electrode plates (6, 7) are provided, which alternate with a separator (8) in between, wherein the housing (2) has a base body (3) open on one side and a cover (5) closing the open side (4) of the base body (3), wherein the positive electrode plates (6) on the one hand and the negative electrode plates (7) on the other hand are each electrically connected to each other by means of a terminal bridge (12, 13), wherein each terminal bridge (12, 13) carries a terminal pole (14, 15), wherein the terminal poles (14, 15) project through a respective opening (16) in the cover (5), characterized in thatthat the connecting pole (15) of the positive electrode plates (6) is longitudinally displaceable from the associated through-hole (16) in relation to the cover (5). Accumulator according to claim 1, characterized in that the terminal pole (15) is fluid-sealed against the cover (5). Accumulator according to claim 1 or 2, characterized in that the terminal pole (15) extends through the passage opening (16) with an intermediate ring body (18) surrounding the terminal pole (15). Accumulator according to claim 3, characterized in that the ring body (18) is arranged in a form-fitting manner on the lid (5). Accumulator according to claim 3 or 4, characterized in that the ring body (18) in the fully assembled state rests on the top of the lid (5) with a circumferential ring part (19) and engages the underside of the lid (5) with a locking tab (21). Accumulator according to one of the preceding claims 3 to 5, characterized in that the ring body (18) carries a first seal (23) on the through-opening side. Accumulator according to one of the preceding claims 3 to 6, characterized in that the ring body (18) carries a second seal (24) on the terminal pole side. Accumulator according to claim 6 or 7, characterized in that the ring body (18) and a seal (23, 24) are made of plastic. Accumulator according to claim 8, characterized in that the plastic material forming the seal (23, 24) is injection molded onto the ring body (18). Accumulator according to one of the preceding claims, characterized in that the terminal pole (15) carries a cap (25) made of plastic. Accumulator according to claim 10, characterized in that the cap (25) is injection molded onto the connection pole (15). Accumulator according to claim 10 or 11, characterized in that the terminal pole (15) has an insert (26) made of an electrically conductive material accessible from the end face. Accumulator according to claim 12, characterized in that the insert (26) provides a threaded bore (27). Accumulator according to claim 12 or 13, characterized in that the insert (26) is made of copper or a copper alloy. Accumulator according to any one of the preceding claims 10 to 14, characterized in that the cap (25) has an opening (28). Accumulator according to one of the preceding claims, characterized in that the terminal pole (15) has a groove (29) on its outer side. Accumulator according to one of the preceding claims, characterized in that the outer pole (15) is equipped on the outside with a coating (30). Accumulator according to one of the preceding claims 10 to 17, characterized in that the outer pole (15) has a foot section (31) which terminates without step in the radial direction with the cap (25).

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