Resistor

Abstract

The invention discloses a resistor (1, 101, 201), in particular a fusible resistor, having a resistance wire (6) forming a resistance element (3), the resistance wire (6) having a wound profile, in particular wound around a longitudinal axis (A). In its wound profile, at least portions of the resistance wire (6) are advantageously completely surrounded by a casing (M) composed of a pulverulent and / or granular arc extinguishing medium (7) of the resistor (1, 101, 201), the casing (M) bearing directly against the resistance wire (6).

Description

[0001] Resistance

[0002] Technical area

[0003] The invention relates to a resistor, in particular a fusible resistor, with a resistance wire forming a resistance element, which resistance wire has a wound course, in particular around a longitudinal axis.

[0004] State of the art

[0005] Resistors, in particular fusible resistors, comprising a resistance element and a thermal fuse electrically connected in series, are known from the prior art (DE112010001694B4).

[0006] The resistance element comprises a resistance wire with a winding path around a longitudinal axis, which is formed by winding it around a rod. The resistance element can withstand comparatively high current loads without melting.

[0007] The fuse, which is electrically arranged downstream of the resistance element, has a fusible part with a winding course around a longitudinal axis, in that this is also wound around an insulating ceramic rod.

[0008] The fuse is melted by the heat emitted by the resistance element, for which the resistance element and the fusible part of the fuse are in thermal connection with each other.

[0009] This is not only comparatively complex to construct, but can also react relatively slowly in its safety function due to its dependence on thermal conductivity. Description of the invention

[0010] The invention therefore aims to improve the stability and operational reliability of a resistor of the type described above while simplifying its design. If necessary, the resistor should also be suitable for a fast-reacting safety function.

[0011] The invention solves the problem by the features of claim 1.

[0012] If the resistor incorporates a powdered and / or granular arc extinguishing agent, the operational reliability of the resistor can be further improved in the event of electrical overload. Furthermore, if the resistance wire is completely enclosed, at least in sections, by a sheath made of the powdered and / or granular arc extinguishing agent, which sheath lies directly against the resistance wire, a relatively stable, resilient resistor can be created that can also be suitable for high-power applications. The coiled configuration makes it possible to preset the resistance value accordingly high—reliably despite comparatively high power levels and the associated comparatively high thermal expansion of the resistance wire.

[0013] The sheath, made of powdered and / or granular arc extinguishing agent, can reliably absorb changes in the length of the resistance wire, thus preventing mechanical damage to the resistance wire. The resistor according to the invention is therefore particularly stable.

[0014] If necessary, the closed and adjacent sheath made of arc quenching agent can, on the one hand, remove the evaporated fusible element from an arc path relatively quickly in the event of a fuse being triggered, and on the other hand, cool an arc relatively quickly. The resistor according to the invention is therefore not only reliable and stable - despite its structural simplicity - but also reacts particularly quickly in the event of a fuse being triggered. For example, the suitability of the resistor for a high-power range can be further improved if the resistance wire absorbs a predetermined energy of at least 0.1 kJ (kilojoules) for charging and / or discharging a capacitor without causing damage. This is even more so if the resistance wire absorbs the predetermined energy of at least 0.5 kJ, for example at least 1.0 kJ, without causing damage.For this purpose, the resistance wire is designed to non-destructively absorb the charging and / or discharging of a capacitor of at least 0.1 kJ (kilojoules), in particular 0.5 kJ, for example of at least 1.0 kJ. It is also conceivable for the resistance wire to non-destructively absorb a predetermined energy for charging and / or discharging a capacitor of at most 5 kJ, in particular of at most 2 kJ. For this purpose, the resistance wire is designed to non-destructively absorb the charging and / or discharging of a capacitor of at most 5 kJ, in particular of at most 2 kJ.

[0015] The specified energy can be determined, for example, under the following conditions: charging or discharging a capacitor with a capacitance C of 2 mF (millifarad) via the resistor while applying a voltage U of 400 V (volts) across the resistor and the capacitor, which are connected in series.

[0016] For example, non-destructive recording can be fulfilled if the resistance value of the resistor changes by a maximum of +- 10%.

[0017] The resistor design can be further simplified if the resistance wire forms a fusible part of a thermal fuse. This eliminates the need for additional structural measures to ensure the resistance and fuse function.

[0018] Preferably, the resistance wire melts when the specified energy for charging and / or discharging a capacitor is exceeded, at the latest when the specified energy is exceeded by 50%, whereby the resistor can reliably fulfil a safety function.

[0019] For example, the resistance wire is designed to melt by 10 to 50% if the specified energy for charging and / or discharging a capacitor is exceeded. This can allow for short-term thermal overloads, preventing unwanted fuse blows and thus further increasing the operational reliability of the fuse resistor. This is even more so if the resistance wire melts by 10 to 20% if the specified energy for charging and / or discharging a capacitor is exceeded.

[0020] The above can be further improved if the sheath made of the arc-quenching agent has a sheath thickness of at least 0.5 mm (millimeters) radially outward from the resistance wire. For example, a sheath thickness of at least 1 mm is particularly advantageous.

[0021] In addition, the sheath can optionally be placed directly on the bare resistance wire to further increase the stability of the melt resistor.

[0022] It is also conceivable that the sheath lies directly on the oxidized surface of the resistance wire.

[0023] For example, the operational reliability of the fusible resistor can be further increased if the sheath completely encompasses at least 90% of the length of the coiled resistance wire. For example, the sheath completely encompasses at least 95% of the length of the coiled resistance wire. It may also be sufficient, for example, if the sheath completely encompasses at least 80% of the length of the coiled resistance wire.

[0024] If the arc extinguishing agent consists of sand, for example, this can be advantageous for rapid arc extinguishing. Preferably, the arc extinguishing agent can consist of quartz sand (SiO2).

[0025] A resistance wire made of NiCr can prove particularly stable despite the specified and comparatively high energy. It is also conceivable for the resistance wire to contain Cr and Ni as alloying elements, for example, a stainless steel wire.

[0026] For example, a dual function of the resistance wire in terms of stability is further improved by winding the resistance wire essentially in a square, circular, spiral and / or helical manner.

[0027] It is also conceivable that the resistance wire runs in a bifilar configuration, for example to minimize or avoid parasitic inductances on the resistance wire.

[0028] The resistor preferably has an electrical resistance of >0.1 ohms, in particular >10 ohms. For example, the resistor can have an electrical resistance of >20 ohms, or >30 ohms, or >40 ohms, or >40 ohms. The electrical resistance of the resistor is preferably in the range of 0.1 to 400 ohms, for example in the range of 0.1 to 100 ohms or in the range of 20 to 400 ohms. The above-mentioned electrical resistance of the resistor preferably also corresponds to the electrical resistance of the resistance wire.

[0029] It is conceivable that the resistor has a rated power P70 in the range of 1 to 250 W (watts). For example, the resistor has a rated power P70 in the range of 3 to 150 W.

[0030] The resistance can be distinguished, for example, if it has a temperature coefficient (TCR) of > 20 ppm / K (10 -6 / Kelvin), e.g. measured according to the standard DIN EN 60115-1. For example, the resistance is > 50 ppm / K. The resistor preferably has a temperature coefficient (TCR) of < 2500 ppm / K, in particular < 2000 ppm / K. The resistor can therefore have a temperature coefficient (TCR) in the range from 20 to 2500 ppm / K or in the range from 50 to 2000 ppm / K. The positioning of the resistance wire in the extinguishing agent can be simplified in design if the fusible resistor has a winding carrier which carries the wound resistance wire. This can also determine the positioning of the resistance wire in the extinguishing agent more securely.

[0031] For example, the winding support can comprise at least two interconnected insulation plates or mica plates that are inclined relative to each other. This can further simplify the design of the resistor. This can be further improved if the winding support has an X-shaped cross-section.

[0032] The positioning of the resistance wire in the extinguishing medium can be simplified in the design if the winding carrier has individual posts spaced apart from one another and the resistance wire runs from one post to the other post - preferably this other post is a nearest post.

[0033] Preferably, the resistor or an assembly comprising the resistor has a housing that encapsulates the resistance wire and the arc-quenching agent. This further simplifies the design.

[0034] The function of the resistor can also be expanded if, for example, the housing has an inner housing with a free interior space, particularly an encapsulated one, with the resistance wire encircling the inner housing. For example, the free interior space can be used for additional electrical / electronic components.

[0035] Preferably, the resistor can be used for an intermediate circuit. In this case, the resistor can reliably form a pre-charging resistor in the intermediate circuit or a discharging resistor in the intermediate circuit.

[0036] Brief description of the drawings The figures show, for example, the subject matter of the invention in more detail using several embodiments.

[0037] Fig. 1 is a three-dimensional view of a resistor with an opened housing according to a first embodiment,

[0038] Fig. 2 is a three-dimensional view of the winding resistance wire of the resistor of Fig. 1,

[0039] Fig. 3 is a three-dimensional view of an assembly with an open housing and with a resistor according to a second embodiment,

[0040] Fig. 4 is a partially opened side view of a resistor according to Fig. 3 with closed housing,

[0041] Fig. 5 is a three-dimensional view of a resistor with an opened housing according to a third embodiment,

[0042] Fig. 6 is a partial side view of the resistor according to Fig. 5,

[0043] Fig. 7 shows a conductor section of the resistance wire with a sheath of arc extinguishing agent of the electrical resistors according to Figures 1 to 6 and Fig. 8 shows a use of the electrical resistor shown in Figures 1 to 6 in an intermediate circuit,

[0044] Ways to implement the invention

[0045] First example:

[0046] According to Figs. 1 and 2, a resistor 1 designed as a component is shown as a first embodiment of the invention, the electrically insulating housing 2, namely the outer housing, being shown open. As can be seen in Fig. 1, the cover 2a has been removed from the housing shell 2b, which is designed as an extruded profile.

[0047] The resistor 1 has a resistance wire 6 forming a resistance element 3, which is electrically connected between two electrical terminals 5a, 5b of the resistor 1. The resistance wire 6 has a winding course around a longitudinal axis A, as can be seen particularly in Fig. 2.

[0048] Resistor 1 also has a thermal fuse 4. The thermal fuse 4 interrupts the electrical connection through the electrical resistor 1 in the event of an electrical overload. For this purpose, the thermal fuse 4 has a fusible part.

[0049] The resistance element 3 can reproducibly absorb a predetermined energy without electrical failure. To make all of this possible according to the invention, the resistance wire 6, in its course wound around the longitudinal axis A, is completely enclosed essentially over its entire wire length by a sheath M made of a granular arc extinguishing agent 7, namely quartz sand (SiO2), which sheath M lies directly against the resistance wire 6. This can be seen in Fig. 7 - in Fig. 2, Fig. 3 and Fig. 5, the arc extinguishing agent 7 has been omitted for reasons of clarity. If the housing 2 is closed, this arc extinguishing agent 7 completely fills this housing 2.

[0050] The resistance element 3 can also enable a fast-reacting thermal fuse with structural simplicity, in that the resistance wire 6 forms the melting part of the fuse 4.

[0051] Thanks to this comprehensive sheath M made of the arc extinguishing agent 7, the resistance wire 6 can reduce thermal stresses through expansion, even at comparatively high energy levels, and thus reliably absorb this thermal load. Furthermore, this sheath M ensures rapid cooling of the arc if the resistance wire 6 evaporates—resulting in a thermal fuse 4 that reacts quickly to electrical overload.

[0052] Advantageously, the resistance wire 6 melts when the specified energy, which is at least 0.5 kJ, is exceeded – and at the latest when the specified energy is exceeded by 20%. Thus, the resistance wire 6 fulfills both an electrical resistance function and a thermal protection function.

[0053] In exemplary embodiment 1, the NiCr resistance wire 6 absorbs a predetermined energy of 1.2 kJ without causing damage and is designed to melt in the range of 10 to 20% if the predetermined energy of 1.2 kJ is exceeded - specifically at an energy in the range of 1.32 kJ to 1.44 kJ, namely at 1.35 kJ. For this purpose, the sheath M made of the arc quenching agent 7 has a sheath thickness d of 1 mm radially outward from the resistance wire 6, wherein the sheath M lies directly against the oxidized surface of the resistance wire 6. In addition, the sheath M completely encompasses at least 95% of the length L of the wound resistance wire 6.

[0054] The resistance wire 5 is wound in a square shape around the longitudinal axis A, as can be seen in Fig. 1 and Fig. 2. To ensure this stability, the resistor 1 has a winding support 8 with an x-shaped cross section.

[0055] For this purpose, the winding support 8 comprises two interconnected mica plates 9a, 9b, namely, in the exemplary embodiment, plugged together, which extend at an angle to each other. On the free longitudinal sides 10 of the mica plates 9a, 9b, successively arranged grooves 11 are provided, through which the resistance wire 6 is wound. The distance between each two successively arranged grooves 11 is greater than twice the wire thickness of 5 mm of the resistance wire 6, namely 10 mm.

[0056] This leads to the following characteristics of resistor 1 :

[0057] Second embodiment:

[0058] 3 and 4, a resistor 101 is shown as a second embodiment of the invention. Unlike resistor 1 according to the first embodiment, resistance wire 6 is not wound around a winding support 8 with an X-shaped cross section, but rather runs around an inner housing 102c of housing 102. For this purpose, inner housing 102c forms posts 120a, 120b, 120c, 120d of winding support 108 on its outer side. This winding support 108 also has mica plates 109a, 109b, 109c, 109d on posts 120a, 120b, 120c, 120d, which support resistance wire 6. The resistance wire 6 runs from one post 120a, 120b, 120c, 120d to another post 120a, 120b, 120c, 120d - wound in a square manner around the longitudinal axis A.In addition, the housing 102 - as shown in the exemplary embodiment - has a housing base 102a and a housing shell 102b that can be placed on the housing base 102a in order to encapsulate not only the resistance wire 6 but also the arc extinguishing agent 7 in the housing 102.

[0059] The recessed inner housing 102c makes it possible to combine the resistor 101 with another electronic component 121, for example a relay, in order to create an assembly 100 with extended electrical functionality.

[0060] This resistor 101 is also designed as a fusible resistor. Just as in the first exemplary embodiment, the NiCr resistance wire 6, in its wound course around the longitudinal axis A, is completely enclosed in sections by a sheath M made of a powdered and / or granular arc quenching agent 7 of the resistor 1, which sheath M lies directly against the resistance wire 6 - as can be seen in Fig. 5. In the exemplary embodiment 101, the NiCr resistance wire 6 absorbs a predetermined energy of 1 kJ non-destructively and is designed to melt if this predetermined energy is exceeded in the range of 10 to 50%, specifically at an energy in the range of 1.1 kJ to 1.5 kJ, namely at 1.5 kJ.

[0061] This leads to the following characteristics of resistor 101 :

[0062] Third embodiment:

[0063] According to Figs. 4 and 5, a resistor 201 is shown as a third embodiment of the invention. Unlike resistors 1 and 101 according to the other embodiments, in this third embodiment, the resistance wire 6 is embedded in the arc extinguishing medium 7 without a winding support. The resistance wire 6 is wound helically around the longitudinal axis A, as can be seen particularly in Fig. 5.

[0064] The housing 202 encapsulates the arc extinguishing agent 7 and for this purpose has a housing cover (not shown) on the lower housing 202a.

[0065] In the embodiment 101, the stainless steel resistance wire 6, which has Cr and Ni as alloying elements, absorbs a predetermined energy of 1.1 kJ non-destructively and is designed to melt when this predetermined energy is exceeded in the range of 10 to 20%, specifically at an energy in the range of 1.1 kJ to 1.32 kJ, namely at 1.25 kJ.

[0066] This leads to the following characteristics of resistor 201 :

[0067] Circuit:

[0068] As can be seen in Fig. 8, the resistor 1, 101, 201 according to the invention is used in an intermediate circuit 12 designed as a voltage intermediate circuit between rectifier 13 and pulse controller 14.

[0069] Resistor 1, 101, 201 serves as a pre-charging resistor to limit the charging current of the intermediate circuit capacitor 15 during startup. After startup, resistor 1, 101, 201 is short-circuited via a switch 16a that is closed for this purpose. Resistor 1, 101, 201 also serves as a thermal fuse for electrical protection.

[0070] In addition, the resistor 1, 101, 201 can be used for discharging—as shown in dashed lines in Fig. 8. Discharge is enabled by closing switch 16b. Such a discharge can occur, for example, when a high-voltage battery of a high-voltage system is disconnected from the load circuit.

[0071] In general, it is noted that "in particular" can be translated into English as "more particularly." A feature preceded by "in particular" is to be considered an optional feature that can be omitted and thus does not constitute a limitation, for example, of the claims. The same applies to "vorzugsweise," translated into English as "preferably."

Claims

Patent claims: 1 . Resistor, in particular a fusible resistor, with a resistance wire (6) forming a resistance element (3), which resistance wire (6) has a wound course, in particular about a longitudinal axis (A), characterized in that the resistor (1, 101, 201) has a powdered and / or granular arc extinguishing agent (7) and that the resistance wire (6) is completely enclosed in its wound course, at least in sections, by a sheath (M) made of the powdered and / or granular arc extinguishing agent (7), which sheath (M) lies directly against the resistance wire (6).

2. Resistor according to claim 1, characterized in that the resistance wire (6) absorbs a predetermined energy for charging and / or discharging a capacitor of at least 0.1 kJ, in particular 0.5 kJ, for example of at least 1.0 kJ, non-destructively and / or that the resistance wire (6) absorbs a predetermined energy for charging and / or discharging a capacitor of at most 5 kJ, in particular of at most 2 kJ, non-destructively.

3. Resistor according to claim 1 or 2, characterized in that the resistance wire (6) forms a fusible part of a thermal fuse (4).

4. Resistor according to one of claims 1 to 3, characterized in that the resistance wire (6) melts when a predetermined energy for charging and / or discharging a capacitor is exceeded, at the latest when the predetermined energy is exceeded by 50% or when the predetermined energy is exceeded by 10 to 50%, in particular by 10 to 20%.

5. Resistor according to one of claims 1 to 4, characterized in that the sheath (M) made of the arc extinguishing agent (7) has a sheath thickness of at least 0.5 mm, in particular of at least 1 mm, from the resistance wire (6) radially outwards.

6. Resistor according to one of claims 1 to 5, characterized in that the sheath (M) lies directly against the bare resistance wire (6) or against the oxidized surface of the resistance wire (6).

7. Resistor according to one of claims 1 to 6, characterized in that the sheath (M) completely encompasses at least 80%, in particular at least 90%, in particular at least 95%, of the length (L) of the wound resistance wire (6).

8. Resistor according to one of claims 1 to 7, characterized in that the arc extinguishing agent (7) consists of sand, in particular quartz sand (SiO2), and / or that the resistance wire (6) is a NiCr wire or has Cr and Ni as alloying elements.

9. Resistor according to one of claims 1 to 8, characterized in that the resistance wire (6) is wound essentially in a square, circular, spiral and / or helical manner and / or in a bifilar manner.

10. Resistor according to one of claims 1 to 9, characterized in that the resistor (1, 101, 201) has an electrical resistance of > 0.1 ohm, in particular > 5 ohm, more preferably > 10 ohm, and / or that the electrical resistance of the resistor (1, 101, 201) is in the range from 0.1 to 400 ohm.

11. Resistor according to one of claims 1 to 10, characterized in that the resistor (1, 101, 201) has a nominal power P70 in the range from 1 to 250 watts, in particular in the range from 3 to 150 watts.

12. Resistor according to one of claims 1 to 11, characterized in that the resistor (1, 101, 201) has a temperature coefficient (TCR) of > 20 ppm / K, in particular > 50 ppm / K, and / or that the resistor (1, 101, 201) has a temperature coefficient (TCR) of < 2500 ppm / K, in particular < 2000 ppm / K.

13. Resistor according to one of claims 1 to 12, characterized in that the resistor (1, 101, 201) has a winding carrier (8a or 108) which carries the wound resistance wire (6).

14. Resistor according to claim 13, characterized in that the winding support (8), which is in particular of X-shaped cross-section, has at least two interconnected insulation plates or mica plates (9a, 9b) which run inclined to one another.

15. Resistor according to claim 13, characterized in that the winding carrier (108) has individual posts (120a, 120b, 120c, 120d) spaced apart from one another, and in that the resistance wire (6) runs from one post (120a, 120b, 120c, 120d) to the other, in particular the nearest, post (120a, 120b, 120c, 120d).

16. Resistor according to one of claims 1 to 14 or assembly with this resistor, characterized in that the resistor (1, 101, 201) or the assembly (100) has a housing (2, 102, 202) which encapsulates the resistance wire (6) and the arc extinguishing means (7).

17. Resistor or assembly according to claim 16, characterized in that the housing (102) has an inner housing (102c) which has a free, in particular encapsulated, inner region, wherein the resistance wire (6) runs around the inner housing (102c).

18. Intermediate circuit, in particular voltage intermediate circuit, with a resistor (1, 101, 201) according to one of claims 1 to 17 or with an assembly (100) according to one of claims 16 or 17, characterized in that the Resistor (1, 101, 201) forms a pre-charging resistor in the intermediate circuit or a discharging resistor in the intermediate circuit.

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