Motor-Pump-Unit

Abstract

Motor-pump unit (1, 1A) with an electric motor (2, 2A) comprising a stator (20A) with at least two poles (22A), a rotor (30A), a commutator (10, 10A) and an eccentric output shaft (7) which drives at least one piston (3.1A, 3.1B) of at least one piston pump (3A, 3B), wherein the electric motor (2, 2A) adapts at least its current torque to a load torque of the at least one piston pump (3A, 3B), wherein the electric motor (2, 2A) is designed such that the highest possible no-load speed is achieved with constant maximum motor current and constant maximum starting torque, and at least two different motor configurations alternate over a complete revolution of the rotor (30A), wherein the motor configurations each have at least one predetermined motor characteristic, wherein the predetermined motor characteristic is a no-load speed or a Regarding starting torque or pre-commutation angle,and wherein the electric motor (2) has a stator with three pole pairs, a rotor with eight rotor teeth, each carrying a rotor winding, and a commutator (10A) with twelve laminations (12A, 12B) and two brushes (14A, 14B) arranged at an angle of 180° to each other.

Description

[0001] The invention relates to a motor-pump unit.

[0002] In known braking systems with ESP and / or ABS functionality (ESP: Electronic Stability Program, ABS: Anti-lock Braking System), a DC motor is typically used to drive two hydraulic pumps via an eccentric. The motor must meet various requirements regarding the relationship between speed and torque. A DC shunt-wound motor, for example, exhibits a largely linear relationship between speed and torque.

[0003] For example, DE 10 2007 034 225 A1 discloses an electric motor for a motor-pump unit for an anti-lock braking system (ABS) in a motor vehicle. The electric motor has a stator and a rotor. The rotor contains rotor teeth and an eccentric output shaft. The distribution and / or dimensioning of the rotor teeth is such that the motor torque follows the load torque in phase and the motor torque is greater than the load torque at every point during a complete revolution of the output shaft.

[0004] From DE 103 05 223 A1, a method for operating a vehicle braking system with a motor-pump unit for conveying hydraulic fluid or increasing pressure is known. The vehicle braking system comprises a master brake cylinder, a housing for the pump, and electromagnetically actuated valves via an electronic controller, as well as channels connecting these components and wheel brakes connected to the housing via hoses and / or pipes. To improve the dynamic behavior of the braking system, it is proposed that information about the pump's operating state be supplied to the electronic controller and that this information be incorporated into the control of the vehicle braking system.

[0005] From DE 10 2007 034 225 A1, an electric motor for the electric motor-pump unit of a motor vehicle anti-lock braking system is known. This motor has a stator and a rotor. The rotor contains rotor teeth and an eccentric output shaft. The distribution and / or dimensioning of the rotor teeth is such that the motor torque follows the load torque in phase and the motor torque is greater than the load torque at every point during a complete revolution of the output shaft.

[0006] German patent DE 10 2008 018 818 A1 discloses a motor-pump unit comprising an electric motor with a stator having at least two poles, a rotor, a commutator, and an eccentric output shaft driving at least one piston of at least one piston pump, as well as an electrical motor control method. The electric motor adjusts its current torque to the load torque of the at least one piston pump. In the electrical motor control method, the electric motor is driven by a pulsed or linearly controllable current source. The motor shaft is connected to a radially driven load, in particular a pump, which exhibits a non-linear torque curve over one motor revolution. Furthermore, a ripple signal is generated from a voltage potential applied to the motor and / or the motor current, and rotor position information is obtained from its shape. Disclosure of the invention

[0007] In contrast, the motor-pump unit according to the invention, with the features of independent claims 1 or 4, has the advantage that the idle speed is increased without increasing the motor current. This allows the performance of the motor-pump unit according to the invention to be advantageously increased.

[0008] Embodiments of the motor-pump unit according to the invention are used, for example, in vehicle braking systems for conveying brake fluid.

[0009] Embodiments of the present invention provide a motor-pump unit with an electric motor comprising a stator with at least two poles, a rotor, a commutator, and an eccentric output shaft that drives at least one piston of at least one piston pump, wherein the electric motor adapts at least its current torque to a load torque of the at least one piston pump. The electric motor is designed to achieve the highest possible no-load speed with a constant maximum motor current and a constant maximum starting torque. The electric motor is designed such that at least two different motor configurations alternate over a complete revolution of the rotor. Each such motor configuration has at least one predetermined motor characteristic relating to a no-load speed, a starting torque, or a precommutation angle.The precommutation angle traverses a predetermined angular range from a minimum precommutation angle to a maximum precommutation angle and back again twice during a complete revolution of the commutator. The electric motor has a stator with three pole pairs, a rotor with eight rotor teeth, each carrying a rotor winding, and a commutator with twelve laminations and two brushes arranged at an angle of 180° to each other.

[0010] The measures and further developments listed in the dependent claims make advantageous improvements to the motor-pump unit specified in independent claim 1 possible.

[0011] For example, if a commutator with two brushes spaced 180° apart is used, the pre-commutation can advantageously be optimized depending on the angle of rotation. Preferably, the commutator has at least ten lamellae. The pre-commutation angle can then be traversed through the angular range in predefined steps, which can be implemented, for example, by different lamella widths and / or different widths of gaps between the lamellae.

[0012] In a further advantageous embodiment of the motor-pump unit according to the invention, the circumferential angle range of the commutator can be assigned to the eccentric output shaft such that the electric motor has the minimum pre-commutation angle in the region of the bottom dead center and in the region of the top dead center of the at least one piston pump, and the maximum pre-commutation angle in the region 90° to the bottom dead center and in the region 90° to the top dead center. This advantageously results in an increased no-load speed with a constant starting torque in the relevant range.

[0013] Alternatively, the electric motor can be designed so that the precommutation angle changes depending on the load torque of the at least one piston pump. In this configuration, the electric motor exhibits a maximum precommutation angle under no load and a minimum precommutation angle under maximum load. The precommutation angle is changed by altering the position of the magnetic poles in relation to the load torque of the at least one piston pump. For implementation, the magnetic poles can be arranged in a pole housing on a pole ring, which can be rotated against a pole spring depending on the load torque of the at least one piston pump. This rotation sets the precommutation angle. The greater the torque demanded of the electric motor, the greater the rotation of the magnet position against the spring force, thus reducing the precommutation angle.With this functionality, the precommutation angle is constantly and optimally adjusted to the load during operation, and the no-load speed is significantly increased without reducing the starting torque or increasing the maximum motor current. Unlike previous solutions, the starting torque in this case is not position-dependent but purely torque-dependent. The electric motor can, for example, have a stator with three pole pairs and a rotor with eight rotor teeth, each carrying a rotor winding.

[0014] Exemplary embodiments of the invention are shown in the drawings and are explained in more detail in the following description. In the drawings, identical reference numerals denote components or elements that perform the same or analogous functions. Brief description of the drawings Fig. Figure 1 shows a schematic representation of an embodiment of a motor-pump unit according to the invention for a vehicle braking system. Fig. Figure 2 shows a schematic representation of a conventional commutator for a conventional electric motor. Fig. Figure 3 shows a schematic representation of an embodiment of a commutator for the motor-pump unit according to the invention. Fig. 1 in a first position. Fig. Figure 4 shows a schematic representation of the exemplary embodiment of the commutator made of Fig. 3 in a second position. Fig. Figure 5 shows a schematic sectional view of an embodiment of an electric motor for the motor-pump unit according to the invention. Fig. 1. Fig. Figure 6 shows a schematic sectional view of an exemplary embodiment of an electric motor. Fig. Figure 7 shows a schematic block diagram of the electric motor. Fig. 6. Embodiments of the invention

[0015] As from Fig. As can be seen in Figure 1, the illustrated embodiment of a motor-pump unit 1, 1A, 1B according to the invention comprises an electric motor 2, 2A, 2B, which drives an eccentric output shaft 7 via its output shaft 5. This eccentric output shaft drives at least one piston 3.1A, 3.1B of at least one piston pump 3A, 3B, and adapts its current torque to a load torque of the at least one piston pump 3A, 3B. As can be seen from Figure 1, the illustrated embodiment of a motor-pump unit 1, 1A, 1B according to the invention comprises an electric motor 2, 2A, 2B, which drives an eccentric output shaft 7 via its output shaft 5. The eccentric output shaft 7 drives at least one piston 3.1A, 3.1B of at least one piston pump 3A, 3B, and its current torque is adapted to a load torque of the at least one piston pump 3A, 3B. Fig. 3, Fig. 4, Fig. 5, Fig. 6 to Fig. As can be seen further in Figure 7, the illustrated embodiments of the electric motor 2, 2A, 2B each comprise a stator 20A, 20B with at least two poles 22A, 22B, a rotor 30A, 30B and a commutator 10, 10A, 10B. The electric motor 2, 2A, 2B is designed such that it achieves the highest possible no-load speed with a constant maximum motor current and a constant maximum starting torque.

[0016] Fig. Figure 2 shows an example of a commutator 10 for a conventional electric motor. The commutator 10 shown comprises twelve equidistantly arranged lamellae 12, each with an angular width of approximately 30° and separated from each other by spacer grooves, and two brushes 14A, 14B, which are arranged at an angle of 180° to each other.

[0017] Unlike the one in Fig. The commutator 10 of a conventional electric motor, as shown in section 2, has a Fig. 3 and Fig. Figure 4 shows a commutator 10A for an electric motor 2 according to the invention, comprising twelve lamellae 12A, 12B, which have either a first angular width of approximately 34° or a second angular width of approximately 26° and are separated from each other by spacer grooves. Furthermore, the commutator 10A of the electric motor 2 according to the invention, analogous to the commutator 10 of the conventional electric motor, comprises two brushes 14A, 14B, which are arranged at an angle of 180° to each other. Fig. Figure 3 shows the commutator 10A of the electric motor 2 according to the invention in an armature position of 0° with a first precommutation angle α1 of 0°, which corresponds to a minimum precommutation angle. Fig. Figure 4 shows the commutator 10A of the electric motor 2 according to the invention in an armature position of 90° with a second pre-commutation angle α2 of 12°, which corresponds to a maximum pre-commutation angle. Starting from a first brush 14A in the Fig. In the anchor position 3 shown, which is 0°, the first three lamellae 12A each have an angular width of approximately 34° in the direction of rotation. The next three lamellae 12B each have an angular width of approximately 26°. Similarly, the first three lamellae 12A in the direction of rotation starting from a second brush 14B in the Fig. The 3 illustrated anchor positions of 0° each have an angular width of approximately 34°. The next three lamellae 12B each have an angular width of approximately 26°. As a result, in the illustrated embodiment, the precommutation angle α changes twice per revolution in steps from the first precommutation angle α1 of 0° to the second precommutation angle α2 of 12° and back to the first precommutation angle α1 of 0°. Due to the illustrated lamella arrangement, the steps are each 4°, so that the precommutation α starting from the in Fig. The anchor position shown in Figure 3 changes from the minimum precommutation angle α1 of 0°, through the intermediate stages of 4° and 8°, to the maximum precommutation angle α2 of 12°, which occurs in the Fig. The anchor position of 90° shown in section 4 is reached. Starting from the position shown in Fig. In the 4th depicted anchor position of 90°, the precommutation α changes from the maximum precommutation angle α2 of 90°, through the intermediate stages of 8° and 4°, to the minimum precommutation angle α1 of 0°, which is reached at an anchor position of 180° (not shown in detail). This process repeats between the anchor position of 180° and the anchor position of 360° (0°).

[0018] Variable precommutation allows the idle speed to be advantageously increased without increasing the maximum current draw or reducing the maximum torque. However, the maximum torque of the electric motor 2 is position-dependent, so the eccentric 7 must be aligned. The circumferential angle range of the commutator 10A is assigned to the eccentric output shaft 7 such that the electric motor 2 has a minimum precommutation angle α1 of 0° at both the bottom dead center (BDC) and top dead center (TDC) of the at least one piston pump 3A, 3B, and a maximum precommutation angle α2 of 12° at both 90° to BDC and 90° to TDC.The electric motor 2 according to the invention can, in addition to the commutator 10A shown, also have a stator (not shown) with three pole pairs and a rotor (not shown) with eight rotor teeth, each carrying a rotor winding.

[0019] Instead of using different lamella widths, interruption grooves of varying widths can be arranged between lamellae of constant width to achieve a precommutation angle that depends on the position of the armature. Other ways to achieve this would include, for example, an elliptical commutator shape or a cam shape, even with multiple cams.

[0020] As from Fig. As can be seen in Figure 5, the illustrated embodiment of the electric motor 2A has a stator 20 with three pole pairs 22A, a rotor 30A with eight rotor teeth 32A, each of which carries a rotor winding 34. As can be seen from Fig. As can be seen further in Figure 5, the electric motor 2A is designed such that the precommutation angle changes depending on the load torque of the at least one piston pump 3A, 3B. In the illustrated embodiment, the magnetic poles 22A are arranged in a pole housing 9A on a pole ring 24, which is rotatable against a pole spring 26 depending on the load torque of the at least one piston pump 3A, 3B and thus sets the precommutation angle. This allows the precommutation angle to be changed by altering the position of the magnetic poles 22A depending on the load torque of the at least one piston pump 3A, 3B. In the illustrated unloaded state, the electric motor 2A has a maximum precommutation angle, and under maximum load, a minimum precommutation angle. This means that the magnetic poles 22A are in the rest position without torque, and the electric motor 2A has a very large precommutation angle.The greater the torque demanded on the electric motor 2A, the more the magnet position is rotated against the spring force of the pole spring 26, thus reducing the precommutation angle. This functionality allows the precommutation angle to be continuously and optimally adjusted to the load during operation, significantly increasing the no-load speed without reducing the starting torque. Unlike the first electric motor 2, the starting torque in this case is not position-dependent but purely torque-dependent. A variable magnet position allows this effect to be used with almost any motor topology. Self-excited motors are particularly suitable due to their existing magnet carrier.

[0021] As from Fig. 6 and Fig. As can be seen in Figure 7, the illustrated embodiment of the electric motor 2B has a stator 20B with a pole pair 22B arranged in a pole housing 9B and a rotor 30B with four rotor teeth 32B, 32C, which are arranged at 90° intervals and each carry a rotor winding 36.1, 36.2, 38.1, 38.2. Two adjacent rotor teeth 32B, 32C have different rotor windings 36.1, 36.2, 38.1, 38.2, while two opposing rotor teeth 32B, 32C have the same rotor winding 36.1, 36.2, 38.1, 38.2. This configuration results in an electric motor 2B in which two different motor configurations alternate over one complete revolution of the rotor 30B.

[0022] This causes the motor characteristics to change every 90° around the circumference, with two different motor characteristics alternating. Thus, two different behaviors (A and B) are available throughout the entire rotation. The sequence is: 0°-90° => A, 90°-180° => B, 180°-270° => A, 270°-360° => B. The sequence then starts again from the beginning. Motor configuration A can be selected to have a low no-load speed and a high starting torque. Configuration B has a high no-load speed and a low starting torque. The angular range with low starting torque is then assigned to the eccentricity of the eccentric output shaft 7 such that the starting torque of the electric motor 2B is always higher than the maximum torque of at least one pump 3A, 3B.

[0023] The motor characteristic curve is aligned and adapted to the eccentric output shaft 7. At maximum lever arm, which occurs at eccentric positions of 90° and 270° to the pump axis, the electric motor 2B has its maximum torque. At the positions of 0° and 180° (bottom dead center and top dead center), the electric motor 2B has its lowest torque but its highest no-load speed. In these positions, additional pre-commutation can be applied to further increase the no-load speed. In the illustrated embodiment, the rotor coils 36.1, 36.2, 38.1, and 38.2 of the electric motor 2B have different numbers of turns. Coils 36.1 and 36.2 have fewer turns than coils 38.1 and 38.2. Furthermore, the wire gauge of coils 36.1 and 36.2 is reduced to limit the starting current. The eccentric output shaft 7, which transmits the torque to the pumps 3A, 3B, is mounted aligned with the armature so that the two torque curves run directly synchronously with each other.

[0024] In the illustrated two-pole motor 2B with a commutator 10B, which has four lamellae 12, a winding 36.1, 36.2 according to design A or a winding 38.1, 38.2 according to design B is placed on each of two opposing teeth 32B, 32C.

[0025] As a first approximation, the following equation (1) can be used for the design: IA[A]=MA[Nm]×NL[rpm] / (UB[V]*9) Here, I represents A the starting current, M A the starting torque, N L the idle speed and U B the supply voltage.

[0026] For example, an electric motor with a required starting torque of 2 Nm and an idle speed of 7000 rpm at 10 V has a starting current of 140 A according to equation (1). Using the invention, the electric motor 2B can be designed as follows: Winding A (starting winding): Starting torque 2.5 Nm, no-load speed 3000 rpm results in a starting current of 75A. Winding B (turbo winding): Starting torque 1 Nm, no-load speed 8000 rpm results in a starting current of 80A.

[0027] Although the starting torque and no-load speed are higher, the motor has a significantly lower current draw. At speeds above the no-load speed of winding A (turbo operation), a diode D is connected to the motor. T upstream, as from Fig. As can be seen in figure 7. This prevents winding A from generating a braking torque (generator operation). This diode D T If necessary, it can be switched on again via a switch S1 to reduce the losses across the diode D. T to minimize. For example, a comparator could be used to measure the voltage across the turbo diode D. TMeasure the voltage and, depending on its direction, switch S1 on or off. Switch S1 can, for example, be implemented as a field-effect transistor (FET). As shown in the diagram... Fig. As can be seen further in Figure 7, a further switch S2 is provided to activate the electric motor 2B and a protective diode D is provided to protect against overvoltages.

[0028] Furthermore, the motor can be controlled in different operating modes by implementing a rotor position sensor. In this mode, depending on the angle, either winding A, winding B, or both windings together are operated at low speeds. The high-power coil B has significantly more turns and a thicker wire than the low-power coil A. The high-power coil B is designed to cover the maximum torque of pumps 3A and 3B. The low-power (turbo) coil A is dimensioned so that its time constant (L / R) is significantly lower than that of the high-power coil B. This dimensioning can be achieved by increasing the ohmic resistance R via the wire length and / or diameter and / or material, and / or by reducing the inductance L via the number of turns. The smaller the time constant, the higher the no-load speed of the electric motor 2B.However, during the design phase, care must be taken to ensure that the minimum torque does not fall below the sine wave of pumps 3A and 3B, so that starting is guaranteed from all positions. Furthermore, the number of turns can be varied by connecting additional windings in parallel or series. The number of turns can also be reduced by adding turns in the opposite direction, which simultaneously increases the ohmic resistance.

Claims

[1] Motor-pump unit (1, 1A) with an electric motor (2, 2A) comprising a stator (20A) with at least two poles (22A), a rotor (30A), a commutator (10, 10A) and an eccentric output shaft (7) which drives at least one piston (3.1A, 3.1B) of at least one piston pump (3A, 3B), wherein the electric motor (2, 2A) adapts at least its current torque to a load torque of the at least one piston pump (3A, 3B), wherein the electric motor (2, 2A) is designed such that the highest possible no-load speed is achieved with constant maximum motor current and constant maximum starting torque, and at least two different motor configurations alternate over a complete revolution of the rotor (30A), wherein the motor configurations each have at least one predetermined motor characteristic, wherein the predetermined motor characteristic is a no-load speed or concerns a starting torque or a pre-commutation angle,and wherein the electric motor (2) has a stator with three pole pairs, a rotor with eight rotor teeth, each carrying a rotor winding, and a commutator (10A) with twelve laminations (12A, 12B) and two brushes (14A, 14B) arranged at an angle of 180° to each other. [2] Motor-pump unit (1, 1A) according to claim 1, characterized by , that the commutator (10A) has at least ten lamellae (12A, 12B), wherein the precommutation angle traverses the angular range in predetermined steps, which are implemented via different lamella widths and / or via different widths of interruption grooves between the lamellae (12A, 12B). [3] Motor-pump unit (1, 1A) according to claim 1 or 2, characterized by, that the circumferential angle range of the commutator (10A) is assigned to the eccentric output shaft (7) such that the electric motor (2) has the minimum pre-commutation angle in the region of the bottom dead center and in the region of the top dead center of the at least one piston pump (3A, 3B) and the maximum pre-commutation angle in the region of 90° to the bottom dead center and in the region of 90° to the top dead center. [4] Motor-pump unit (1, 1A) with an electric motor (2, 2A) which has a stator (20A) with at least two poles (22A), a rotor (30A), a commutator (10, 10A) and an eccentric output shaft (7) which has at least one piston (3.1A, 3.1B) drives at least one piston pump (3A, 3B), wherein the electric motor (2, 2A) adapts at least its current torque to a load torque of the at least one piston pump (3A, 3B), wherein the electric motor (2, 2A) is designed such that the highest possible no-load speed is achieved with constant maximum motor current and constant maximum starting torque, and the precommutation angle changes depending on the load torque of the at least one piston pump (3A, 3B), wherein the electric motor (2A) has a maximum precommutation angle in the unloaded state and a minimum precommutation angle under maximum load, wherein the precommutation angle can be changed by changing the position of the magnetic poles (22A) depending on the load torque of the at least one piston pump (3A, 3B). [5] Motor-pump unit (1, 1A) according to claim 4, characterized by, that the magnetic poles (22A) are arranged in a pole housing (9A) on a pole ring (24), which is rotatable against a pole spring (26) depending on the load moment of the at least one piston pump (3A, 3B) and sets the precommutation angle. [6] Motor-pump unit (1, 1A) according to claim 4 or 5, characterized by , that the electric motor (2A) has a stator (20) with three pole pairs (22A), a rotor (30A) with eight rotor teeth (32A), each of which carries a rotor winding (34).

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