DE102018216352A1 - NTC resistance module - Google Patents

Abstract

An NTC resistance module in the circuit of an electrically actuatable device has an NTC element, the material of which is an oxide material with a perovskite structure.

Description

The invention relates to an NTC (Negative Temperature Coefficient) resistance module in the circuit of an electrically actuatable device, for example in the circuit of an electrical machine, for example an electric drive motor or an electric starter motor in a starting device for an internal combustion engine.

State of the art

Starting devices for internal combustion engines are known which have an axially adjustable starter pinion on a drivable shaft which is driven by an electric starter motor. The starter pinion is adjusted by an electromagnetic starter relay from a retracted disengaged position to an advanced engaged position with a ring gear of the internal combustion engine.

From the DE 10 2007 036 789 A1 A starting device for internal combustion engines is known in which an NTC resistance element (Negative Temperature Coefficient) is arranged in the circuit of a winding of the starter relay.

From the DE 10 2016 215 142 A1 a starting device for internal combustion engines is known in which an NTC resistance element is integrated in the circuit of the electric starter motor.

With the help of the NTC resistance element, which has a higher electrical resistance at low temperatures and a lower resistance with increasing temperature, it is possible to limit the starter current when the internal combustion engine starts. Due to the current-reducing effect of the NTC resistance element, the voltage drop in the vehicle electrical system can be reduced.

Disclosure of the invention

The NTC (Negative Temperature Coefficient) resistance module according to the invention can be used in the circuit of an electrically actuatable device, for example in the circuit of an electrical machine. For example, use of the NTC resistor module in an electric drive motor for a vehicle is contemplated. In a further possible application, the NTC resistance module is used in an electrically actuatable device of a starting device for starting an internal combustion engine, in particular in a motor vehicle, the starting device having a starter motor and an electromagnetic starter relay as electrically actuable devices. Via the starter relay, the starter pinion of the starter device can be adjusted between a retracted non-functional position and an advanced engagement position in which the starter pinion is in engagement with a ring gear of the internal combustion engine. The starter motor rotates the starter pinion.

An NTC resistance module with an NTC element made of an NTC material is arranged in the circuit of an electrically actuated device, the electrical resistance of which decreases with increasing temperature. When used in an electric drive motor or in a starting device when the internal combustion engine is started for the first time, the NTC element in the NTC resistance module has an increased electrical resistance due to the low temperature, as a result of which the electrical current is limited and current peaks are avoided. Since the electrical device, in whose circuit the NTC resistance module is integrated, depends on the voltage supply of the vehicle electrical system, a voltage drop in the vehicle electrical system is avoided, or at least reduced, with the help of the NTC resistance module.

The NTC element of the NTC resistance module consists of an NTC material which is designed as an oxide material with a perovskite structure. The perovskite structure is, for example, a cubic, orthorhombic or rhombohedral crystal structure. NTC elements made of such an NTC material are particularly advantageously suitable for use in an electrically actuatable device such as, for example, in the circuit of an electrical machine or in starting devices for internal combustion engines. The electrical properties of the oxide material with a perovskite structure can be modified in a simple manner, for example by influencing the electrical conductivity, the thermal expansion coefficient or the temperature coefficient by adding doping elements. By adapting the thermal expansion coefficient of the NTC material, for example, to a surrounding envelope body of the NTC resistance module, for example, thermal stresses can be avoided, which in particular improves long-term stability.

According to an advantageous embodiment, the NTC material is a lanthanum (La) -based perovskite. This has in particular a composition of the form La _1-x A _x (B _1-y D _y ) O _{3 + δ} where A is an alkaline earth metal and B and D are a transition metal. For example, calcium (Ca), strontium (Sr) or barium (Ba) are suitable as alkaline earth metal A. Suitable transition metals B and D are, for example, manganese (Mn), iron (Fe), chromium (Cr), copper (Cu) or nickel (Ni). In a particularly preferred embodiment, the NTC material is a La _0.8 Sr _0.2 FeO _{3 + δ} . In the case of La _0.8 Sr _0.2 FeO ₃ , the material has a specific resistance of 23 Ωcm at 20 ° C, a temperature coefficient of 3345 K and a thermal expansion coefficient of 10.1 × 10 ^-6 / K. If necessary, La can be replaced by Gd, Nd or Sm.

According to yet another advantageous embodiment, the NTC material used for the NTC element has a specific resistance between 1 Ωcm and 25 Ωcm at 300 K, which has a B value between 300 K and 500 K in a range between 1000 K and 5000 K. . For example, La _0.8 Sr _0.2 FeO _{3 has} a B value on the order of 3500 K.

In addition to the NTC element, the NTC resistance module can also comprise two electrodes which are arranged on opposite sides of the NTC element and are in electrical contact with the latter. The NTC element and the electrodes can be accommodated in a housing or enveloping body.

• 1 einen Schnitt längs durch eine Startvorrichtung für eine Brennkraftmaschine, wobei im Stromkreis eines elektrischen Startermotors ein NTC-Widerstandsmodul angeordnet ist,
• 2 eine schematische Darstellung eines NTC-Widerstandsmoduls mit einem NTC-Element und zwei Elektroden in einem Hüllkörper,
• 3 ein Schaubild mit der logarithmischen Arrhenius-Darstellung von verschiedenen NTC-Materialen mit unterschiedlicher elektrischer Leitfähigkeit,
• 4 ein weiteres Schaubild mit der logarithmischen Arrhenius-Darstellung von verschiedenen NTC-Materialen mit unterschiedlicher elektrischer Leitfähigkeit.

Further advantages and expedient designs can be found in the further claims, the description of the figures and the drawings. Show it:

• 1 2 shows a section along a starting device for an internal combustion engine, an NTC resistance module being arranged in the circuit of an electric starter motor,
• 2nd 1 shows a schematic representation of an NTC resistance module with an NTC element and two electrodes in an enveloping body,
• 3rd a diagram with the logarithmic Arrhenius representation of different NTC materials with different electrical conductivity,
• 4th another diagram with the logarithmic Arrhenius representation of different NTC materials with different electrical conductivity.

In the figures, the same components are provided with the same reference symbols.

In the 1 starting device shown 1 is used to start internal combustion engines and has a housing that forms a bearing plate 2nd an electric starter motor 3rd on, a gear 4th , which is designed as a planetary gear, a drive shaft 5 , a one-way clutch 6 as well as a starter pinion 7 , which is to be adjusted axially between a retracted disengagement position and an advanced engagement position (shown in dashed lines) in which the starter pinion 7 in engagement with a ring gear 23 the internal combustion engine is stopped. The axial adjustment movement of the starter pinion 7 using an electromagnetic starter relay 8th carried out on the end shield 2nd the starter 1 is held or flanged.

The starter motor 3rd is in the embodiment as a permanent magnet DC motor with permanent magnets 9 on the inside of the motor or pole housing 10th executed. The starter motor 3rd has an anchor 11 with a rotating armature shaft 12th on, one on the armature shaft 12th mounted anchor package 13 with energizable windings and a commutation device 30th with a collector 14 for power transmission and application to the windings of the armature package 13 .

The planetary gear 4th is from the armature shaft 12th of the starter motor 3rd driven and has a ring gear fixed to the housing 15 with internal toothing, planet gears 17th on a planet carrier 18th as well as a central sun gear 19th on. The gear parts are in a gear housing component 16 added. The sun gear 19th sits on the front of the armature shaft 12th on and is non-rotatable with the armature shaft 12th connected. The sun gear 19th combs with the planet gears 17th , which is also on the toothed inside of the ring gear 15 unroll. The planet gears 17th are rotatable on shafts on the planet carrier 18th stored, the rotationally fixed with the drive shaft 5 is connected to the starter pinion 7 sits on. In this way, the drive movement of the armature shaft 12th of the starter motor 3rd about the planetary gear 4th in a rotary motion of the drive shaft 5 implemented. The gear 4th has the function of a reduction gear.

The one-way clutch 6 includes a driver 20th and sits on the drive shaft 5 on. The driver 20th is over a steep thread 21 with the drive shaft 5 coupled. To the one-way clutch 6 also includes a pinion shaft 22 which are in one piece with the starter pinion 7 trained and with that of the driver 20th is rotationally coupled via rolling elements. The one-way clutch 6 allows torque transmission in the direction of rotation or drive of the starter motor, whereas movement or torque transmission is not possible in the opposite direction. This ensures that damage to the starter motor is avoided when the internal combustion engine is started when the sprocket is overhauled relative to the starter pinion.

The axial adjustment movement of the starter pinion 7 is activated by actuating the electromagnetic starter relay 8th generates an axially adjustable lifting anchor 24th which has a fork lever 25th with the driver 20th is coupled. When the starter relay is actuated 8th becomes the lifting anchor 24th axially adjusted, this adjustment movement is via the fork lever 25th in an axial deflection movement of the driver 20th and starter pinion 7 implemented. Due to the coupling of the driver 20th over the steep thread 21 with the drive shaft 5 guides the one-way clutch during the axial feed movement 6 including starter pinion 7 a rotational movement, which facilitates the engagement in the ring gear in a tooth-on-tooth position.

Once the starter pinion 7 has reached its axially advanced engagement position with the ring gear, the electric starter motor 3rd started and the rotational movement of the armature shaft 12th on the starter pinion 7 transfer.

The starting device 1 is designed to emit freely. The drive shaft 5 is in the area of its free face in the housing or end shield 2nd received in an open recess and there in a warehouse 26 rotatably mounted. Axially adjacent to the bearing 26 is located on the inside of the end shield 2nd a stop ring 27 on the drive shaft 5 , which is axially fixed to the drive shaft 5 connected is. The drive shaft 5 for this purpose has a circumferential groove into which the stop ring 27 or the stop ring 27 load-bearing circlip is inserted.

The windings in the anchor package 13 are via the commutation device 30th energized. In the circuit in which the commutation device 30th is arranged, there is an electrical connection cable 28 that is electrically connected to an NTC (Negative Temperature Coefficient) resistor module 29. The circuit of the commutation device 30th is from the electrical starter relay 8th when a starter relay lifting armature is deflected 8th closed. The NTC resistance module 29 in the circuit of the commutation device 30th of the electric starter motor 3rd conducts the electric current better at high temperatures than at low temperatures and thereby compensates for the reverse behavior of the electric starter motor, so that a balanced behavior of the starter motor is achieved over a wider temperature range. The commutation device 30th includes the collector 14 , the rotatable with the armature shaft 12th of the starter motor 3rd is connected, as well as brushes which are adjustably mounted in brush guides and which are located in the circuit.

An NTC resistance module can also be connected to the starter relay circuit 8th be integrated.

In 2nd is a resistance module 29 represented in a schematic manner. The resistance module 29 includes an NTC element 31 and two electrodes 32 and 33 on opposite sides in electrical contact with the NTC element 31 stand. NTC element 31 is from an envelope 34 which also enclosed the electrodes 32 and 33 partially includes and fixes them.

wobei

σ

die elektrische Leitfähigkeit in der Einheit S/cm

T

die absolute Temperatur in der Einheit K

E_A

die Aktivierungsenergie in der Einheit kJ/mol

bedeuten. 3rd shows a graph with the logarithmic Arrhenius representation of various NTC materials C1 , C2 , C3 and C4 for an NTC element, the NTC materials C1 , C2 , C3 and C4 have different electrical conductivities σ. The x axis in 3rd shows the temperature inverse in the unit [1 / K], the y-axis the logarithm In (σT) according to the Arrhenius representation of the electrical conductivity of the NTC material: $$\text{ln}\left(\sigma \cdot T\right)=-\frac{E_A}{k_B}\cdot \frac{1}{T}$$

in which

σ

the electrical conductivity in the unit S / cm

T

the absolute temperature in the unit K

E _A

the activation energy in the unit kJ / mol

mean.

The temperature in the unit [° C] is plotted in the x direction at the top of the diagram.

The properties of the NTC materials C1 , C2 , C3 and C4 are shown in the following table: composition Specific resistance p [Ωcm] at 20 ° C B value [K] (-19 ° C - 129 ° C) α [10 ^-6 / K] (100 ° C - 300 ° C) C1 La _0.8 Sr _0.2 FeO ₃ 23 3345 10.1 C2 La _0.6 Sr _0.4 FeO ₃ 0.6 2382 11.9 C3 La _0.8 Ca _0.2 FeO ₃ 96 3187 10.6 C4 La _0.8 Ba _0.2 FeO ₃ 11 3352 9.8

4th shows another diagram in which various NTC materials with different electrical conductivity σ are plotted in the logarithmic Arrhenius representation. The NTC material C1 corresponds to that from 3rd , in addition, the courses of other NTC materials C5 , C6 , C7 and C8 each with different electrical conductivity σ, the properties of which are shown in the following table: composition Specific resistance p [Ωcm] at 20 ° C B value [K] (-19 ° C - 129 ° C) α [10 ^-6 / K] (100 ° C - 300 ° C) C1 La _0.8 Sr _0.2 FeO ₃ 23 3345 10.1 C5 Nd _0.8 Sr _0.2 FeO ₃ 5 2998 11.7 C6 Sm _0.8 Sr _0.2 FeO ₃ 9 3304 10.7 C7 Gd _0.8 Sr _0.2 FeO ₃ 12th 2758 11.3 C8 (Nd _0.5 Gd _0.5 ) _0.8 Sr _0.2 FeO ₃ 4th 3165 11.3

wobei T₁, T₂ die absolute Temperatur an zwei verschiedenen Punkten und ρ₁, ρ₂ der zugeordnete spezifische Widerstand ist. Die Kurven C_i in den Schaubildern gemäß den 3 und 4 stellen Messwerte mit einem Linearverhalten in einem bestimmten Temperaturbereich dar, aus denen bei definierten Temperaturen die B-Werte bestimmt werden können.The NTC materials mentioned are La-based perovskites with an alkaline earth metal such as calcium, strontium or barium and a transition metal such as manganese, iron, chromium, copper or nickel. The materials have a B value between 300 K and 500 K, which is in a range from 1000 K to 5000 K. The B value is defined as $$B=\frac{T_1\cdot T_{\mathrm{2nd}}}{T_{\mathrm{2nd}}-T_1}\cdot \text{ln}\frac{{\rho }_1}{{\rho }_{\mathrm{2nd}}},$$

where T ₁ , T _{2 is} the absolute temperature at two different points and ρ ₁ , ρ _{2 is} the assigned specific resistance. The curves C _i in the graphs according to the 3rd and 4th represent measured values with a linear behavior in a certain temperature range, from which the B values can be determined at defined temperatures.

QUOTES INCLUDE IN THE DESCRIPTION

This list of documents listed by the applicant has been generated automatically and is only included for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Patent literature cited

• DE 102007036789 A1 [0003]
• DE 102016215142 A1 [0004]

Claims (9)

NTC (Negative Temperature Coefficient) resistance module (29) in the circuit of an electrically actuatable device (2), for example in the circuit of an electrical machine, characterized in that the NTC resistance module (29) is an NTC element (31) made from an NTC Has material that is an oxide material with a perovskite structure. NTC resistance module after Claim 1 , characterized in that the NTC material of the NTC element (31) is a lanthanum (La) -based perovskite. NTC resistance module after Claim 2 , characterized in that the La-based perovskite is a composition of the form La _1-x A _x B (B _1-y D _y ) O _{3 + δ} has, wherein A is an alkaline earth metal B and D are transition metals. NTC resistance module after Claim 3 , characterized in that the alkaline earth metal A A = calcium (Ca), strontium (Sr) or barium (Ba). NTC resistance module after Claim 4 , characterized in that the transition metals B and D are manganese (Mn), iron (Fe), chromium (Cr), copper (Cu) or nickel (Ni). NTC resistance module according to one of the Claims 2 to 5 , characterized in that the NTC material of the NTC element (31) is a La _0.8 Sr _0.2 (Fe _1-y Mn _y ) O _{3 + δ} with y = 0, 0.2, 0.8 or 1 NTC resistance module according to one of the Claims 1 to 6 , characterized in that the NTC material of the NTC element (31) has an electrical conductivity (σ) or a specific resistance (p) which or between 300 K and 500 K has a B value in a range of 1000 K to 5000 K. Electrically actuated device, in particular an electrical machine, in whose circuit an NTC resistance module (29) according to one of the Claims 1 to 7 is arranged. Electrically operated device according to Claim 8 , characterized in that the electrically actuatable device (2), in the circuit of which the NTC resistance module (29) is arranged, is the electric starter motor (3) of a starting device (1) for an internal combustion engine.

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