ELECTRIC MOTOR FOR A POSITIONING OR CONVEYING DEVICE OF A MOTOR VEHICLE

Description

[0001] The invention relates to an electric motor for a positioning or conveying device of a motor vehicle, comprising a stator with a first winding and a second winding, wherein the second winding and the first winding can be controlled independently of one another, in particular with a phase shift, a rotor which magnetically interacts with the magnetic fields generated by energizing the windings, and a sensor device for detecting a position of the rotor.

[0002] Such electric motors for actuating or conveying devices are known in the art in a wide variety of designs. Such devices include, in particular, different valves, wherein the electric motor can adjust a valve body between different positions in steps or continuously. One example is expansion valves, which serve to reduce the pressure of a working fluid by throttling the available flow cross-section, which can be varied by the valve body, and to increase the volume of the working fluid, i.e. to expand it. By using controlled expansion valves, both the pressure drop and thus the increase in volume can be regulated and the fluid flow can be almost completely interrupted. A conveying device includes, in particular, pumps orCompressor is to be understood, whereby the electric motor, in contrast to positioning devices which move to different positions, serves to continuously drive a pump or compressor rotor, whereby a fluid is continuously pumped.

[0003] One embodiment of an electric motor for positioning or conveying devices has a stator with two windings. When the windings are energized, a magnetic field is generated in different directions depending on the current direction of the energized windings. The magnetic field generated by the energization of the windings interacts with a magnetized rotor, thereby driving the rotor and causing it to rotate around an axial axis.

[0004] Electric motors also differ in the type of commutation. Brushless motors are further differentiated between sensorless and sensor-controlled commutation. Electric motors with sensor-controlled commutation typically include a sensor device with multiple Hall sensors for detecting the rotor position by sensing the rotor's magnetic field. The stator windings are controlled via appropriate control electronics based on the rotor position. The key advantage of sensor-controlled commutation is that the electric motor can be operated even at very low speeds or while stationary.

[0005] Such an electric motor is disclosed, for example, in DE 10 2015 106 890 A1. The electric motor is designed as a two-phase stepper motor, wherein the two phases are controlled with a phase shift of 90° to one another. The electric motor further comprises either a sensor device with a single Hall sensor, wherein a second output signal is derived from a first output signal by differentiation, or two Hall sensors, each with one output signal. The two output signals are used for the phase-shifted control of the two windings. A disadvantage of the first embodiment, i.e. with a single Hall sensor, is that determining the second output signal is complex and can only take place upon movement, in particular rotation, of a magnetic field interacting with the Hall sensor.This makes the first design particularly unsuitable for positioning devices where the rotor speed is relatively low. The second design, with two Hall sensors, has the disadvantage that sufficient space must be available for both Hall sensors. Furthermore, the two Hall sensors increase the cost and assembly effort of the electric motor.

[0006] Furthermore, JP 2015 114208 A and DE 10 2020 112 658 A1 each disclose an electric motor with a two-phase stator, wherein the rotational angle position of the rotor required for controlling the stator is determined by a multi-axis Hall sensor. In the version of DE 10 2020 112 658 A1, the stator is designed as a claw-pole stator.

[0007] Furthermore, from US 2017 / 244345 A1 an actuator for a flap or for a valve for adjusting a gaseous or liquid volume flow is known, wherein the actuator has a brushless two-phase DC motor and a Hall sensor.

[0008] The task is to provide an electric motor in which the independent or phase-shifted control of the two windings can be carried out in a simple, reliable, space-saving and cost-effective manner.

[0009] This object is achieved by an electric motor for a positioning or conveying device of a motor vehicle having the features of claim 1.

[0010] The electric motor according to the invention comprises a sensor device with a multi-phase Hall element with two output signals. The first output signal is assigned to the first winding, so that the first winding is controlled by the first output signal. The second output signal is assigned to the second winding, so that the second winding is controlled by the second output signal.

[0011] The multi-axis Hall element has several axes aligned perpendicular to each other, i.e., 90° to each other. The multi-axis Hall element can detect magnetic field lines aligned along the axes and the associated magnetic flux density. In other words, the multi-axis Hall element detects two different components of the magnetic flux density. The detected magnetic flux density, and thus the output signals, change depending on the rotor position. The magnetic flux density changes in the respective direction between a maximum and a minimum, with the maximum and minimum of the first axis being phase-shifted from the maximum and minimum of the second axis.

[0012] Because the axes are aligned at 90° to each other, the output signals of the multi-axis Hall element are phase-shifted. The phase shift of the output signals corresponds to the phase shift required to control the two windings. This allows the output signals of the multi-axis Hall element to be used unchanged, or almost unchanged, to control the two windings. This creates a direct link between the rotor position and the control of the windings.

[0013] The stator is a claw-pole stator, with the claw-pole stator comprising two, preferably identical, claw-pole stator elements arranged axially adjacent to one another, each with a winding and a pair of claw-pole laminations. A claw-pole stator, or a claw-pole motor with two claw-pole stator elements, is a two-phase electric motor that can be manufactured simply and cost-effectively and is particularly well-suited for low speeds.

[0014] Each pair of claw pole plates comprises two claw pole plates, each having a plate-like section and a plurality of claws extending axially from the plate-like section and distributed over the circumference. When assembled, the plate-like sections are arranged at opposite axial ends of the windings, and the claws of the claw pole plates each engage in the free areas between the claws of the opposite claw pole plate. When current is applied to the winding, the claw pole plates, and in particular the claws, are magnetized opposite to one another, with the magnetization depending on the direction of current flow in the winding.

[0015] A first claw-pole stator element is arranged electrically rotated by 90° relative to a second claw-pole stator element. This allows for a two-phase claw-pole motor, whereby the 90° rotation of the claw-pole stator elements requires a 90° phase-shifted control of the two windings, and the required phase-shifted control of the windings can be achieved directly by the output signals of the multi-axis Hall element.

[0016] By designing the electric motor with a multi-axis Hall element, the control, especially the phase-shifted control, of the two windings can be achieved in a simple, reliable, space-saving, and cost-effective manner. Only one Hall element is required, eliminating the need for complex output signal processing. Furthermore, this allows for fine resolution when detecting the rotor position.

[0017] Preferably, the magnetic poles assigned to the first winding are arranged rotated relative to the magnetic poles assigned to the second winding, wherein the phase shift between the two output signals of the multi-axis Hall element is identical to the electrical rotation between the two magnetic poles assigned to the two windings. In a preferred embodiment, the magnetic poles assigned to the first winding are arranged electrically rotated by 90° relative to the magnetic poles assigned to the second winding. Because the electrical rotation of the magnetic poles assigned to the two windings relative to one another corresponds to the phase shift of the two output signals, a fixed connection can be established between the output signals and the control of the windings.

[0018] Preferably, the magnetic poles assigned to the first winding are arranged mechanically rotated by an angle of 90° / number of pole pairs relative to the magnetic poles assigned to the second winding. With eight magnetic pole pairs, the angle is 11.25°, whereby this mechanical rotation corresponds to an electrical rotation of 90°.

[0019] Preferably, the multi-axis Hall element is a multi-axis Hall switch, wherein the multi-axis Hall switch can be switched to a first switching state when a magnetic field threshold is exceeded and to a second switching state when the magnetic field threshold is exceeded. In other words, the multi-axis Hall switch detects, for each axis, whether a sufficiently high magnetic flux density is present during rotation of the rotor. The switching states result in a sinusoidal output signal for each axis. Due to the 90° arrangement of the two axes to each other, a sinusoidal first output signal is generated for controlling the first winding and a cosinusoidal second output signal is generated for controlling the second winding. This allows the windings to be controlled in a simple manner with a phase shift depending on the rotor position.

[0020] The rotor preferably has a plurality of permanent magnets or a plurality of permanently magnetized regions, wherein the permanent magnets or the magnetized regions are arranged or designed such that a north pole and a south pole are arranged alternately across an annular cross-section. In a preferred embodiment, the multi-axis Hall element interacts with the permanent magnets or the magnetized regions of the rotor to detect the rotation angle of the rotor, wherein the rotor protrudes axially from the stator, and the multi-axis Hall element is arranged on a protruding section of the rotor. As a result, the permanent magnets or the magnetized regions of the rotor can be used to determine the rotor position, so that no additional sensor magnet is required.The functionality is also maintained with a rotor that is flush with the stator, although the detection of the magnetic field is improved with a rotor that protrudes from the stator.

[0021] The multi-axis Hall element is preferably a two-axis Hall element or a three-axis Hall element. With a three-axis Hall element, only two axes spanning a single plane are used for the two output signals. The three-axis Hall element can be arranged in any orientation. The axes aligned in the radial and tangential directions of the rotor are used for the output signals.

[0022] In a preferred embodiment, both claw-pole plates of a claw-pole plate pair each have eight claws, and the rotor is designed with 16 poles. This allows for fine resolution in the control and in determining the rotor position. In a 16-pole rotor, i.e., with eight magnetic pole pairs, the claw-pole stator elements are arranged mechanically rotated relative to one another around an axial axis of the stator by an angle of 11.25°, which results from 90° per magnetic pole pair.

[0023] Thus, an electric motor for a positioning or conveying device of a motor vehicle is provided, in which the control of the two windings can be carried out in a simple, reliable, space-saving and cost-effective manner.

[0024] An embodiment of an electric motor according to the invention is shown in the figures and is described below. Figure 1shows a valve with an electric motor according to the invention in a sectional view. Figure 2 shows a stator, a rotor and a multi-axis Hall element of the electric motor from Figure 1 in perspective view. Figure 3 shows schematically the rotor and the multi-axis Hall element of the electric motor from Figure 1 as well as the course of two output signals of the two multi-axis Hall elements.

[0025] The Figure 1 shows an actuating device 2, in particular for a refrigerant or air conditioning circuit. The device 2 comprises an actuator 10 and a multi-part housing 11, wherein the actuator 10 is arranged in the housing 11 and the valve components are arranged on or in the housing 11. The actuator 10 comprises an electric motor 12, an electronics unit 58, and a spindle gear 60.

[0026] The electric motor 12 is designed in the form of a permanent-magnet synchronous motor, in particular in the form of a claw-pole motor. The electric motor 12 has a claw-pole stator 14 with two axially adjacent claw-pole stator elements 16, 18, wherein the two claw-pole stator elements 16, 18 each have a winding 20, 22 and a pair of claw-pole sheets 24, 26. The pairs of claw-pole sheets 24, 26 each have two claw-pole sheets 28, 30, 32, 34 and a return plate 31, 33, wherein the claw-pole sheets 28, 30, 32, 34 each have a plate-like section and a plurality of claws 38 extending perpendicularly from the plate-like sections.The claws 38 of a claw pole plate 28, 30, 32, 34 of a claw pole plate pair 24, 26 engage in a space between adjacent claws 38 of the other claw pole plate 28, 30, 32, 34 of the same claw pole plate pair 24, 26, so that the claws 38 of the claw pole plates 28, 30, 32, 34 are arranged alternately in the circumferential direction. When current is applied to the winding 20, 22, the claw pole plates 28, 30, 32, 34 of a claw pole plate pair 24, 26 are magnetized depending on the current direction of the winding 20, 22 and the resulting magnetic field, wherein when current flows in a first direction, the claws 38 of a first claw pole plate 28, 32 each form a north pole and the claws 38 of a second claw pole plate 30, 34 corresponding to the first claw pole plate 28, 32 each form a south pole.When current flows in a second direction, the magnetization of the claw-pole plates 28, 30, 32, 34 changes, so that the first claw-pole plate 28, 32 forms the south pole and the second claw-pole plate 30, 34 forms the north pole. Each claw-pole plate 28, 30, 32, 34 has eight claws 38, so that each claw-pole stator element 16, 18 has 16 poles.

[0027] The claw pole stator elements 16, 18 are arranged directly next to one another in the axial direction, wherein the magnetic poles of the claw pole stator elements 16, 18 formed by the claws 38 are arranged mechanically rotated relative to one another by an angle of 11.25° about an axial axis A. The rotated arrangement of the claw pole stator elements 16, 18 is shown in Figure 2shown. A rotation of the claw-pole stator elements 16, 18 by 11.25° corresponds to an electrical rotation of 90° with eight magnetic pole pairs of the claw-pole stator elements 16, 18. Such an arrangement of the claw-pole stator elements 16, 18 requires a 90° phase-shifted control of the two windings 20, 22.

[0028] The electric motor 12 further comprises a rotor 40, which is designed with 16 poles and has corresponding magnetized regions. The regions are configured such that eight north poles N and eight south poles S are provided, with the south poles S and the north poles N being arranged alternately in the circumferential direction. The arrangement of the magnetized regions of the rotor 40 is shown in Figure 3 shown, with the magnetic field between a north pole and a south pole being shown as an example.

[0029] The electric motor 12 also has a sensor device 50 with a multi-axis Hall element 52. The multi-axis Hall element 52 is arranged on the electronics unit 58 and protrudes, as shown in Figure 2 shown, in the direction of the rotor 40. For this purpose, the rotor 40 is designed longer than the claw-pole stator 14, whereby the multi-axis Hall element 52 can detect the magnetic fields of the rotor 40. The rotor 40 can also be designed flush with the claw-pole stator 14, whereby the magnetic fields of the rotor 40 can also be detected by the multi-axis Hall element 52. Alternatively, a separate permanent magnet could be arranged on the rotor 40, which interacts with the multi-axis Hall element 52.

[0030] The multi-axis Hall element 52 is designed as a two-axis Hall switch 53 and has two output signals S1, S2, with two perpendicular axes A1, A2 each assigned an output signal S1, S2. Alternatively, a three-axis Hall switch or sensor can be used, with two axes spanning a plane being assigned to the output signals S1, S2.

[0031] The functionality of the two-axis Hall switch 53 with respect to the output signals S1, S2 is such that a circuit of the two-axis Hall switch 53 switches to a first switching state when a predefined magnetic field threshold is exceeded, and switches to a second switching state when the magnetic field threshold is below. A signal corresponding to the magnetization of the rotor 40, in particular a sinusoidal signal, is generated from the detected switching states.

[0032] The Figure 3shows schematically the arrangement of the two-axis Hall switch 53 on the rotor 40 as well as the curves of the magnetic flux densities M1, M2 in the direction of the two axes A1, A2 and the output signals S1, S2 of the two-axis Hall switch 53 used to control the windings 20, 22. During operation, the rotor 40 rotates and the two-axis Hall switch 53 detects the magnetic field line aligned in the direction of the axes A1, A2 and the associated magnetic flux density. In other words, the two-axis Hall switch 53 detects two different components of the magnetic flux density. The detected magnetic flux densities M1, M2 change with the rotation of the rotor 40 between a maximum and a minimum, wherein the Figure 3shown curves of the two magnetic flux densities M1, M2 are phase-shifted by 90°, i.e. n / 2, from each other. The two-axis Hall switch 53 switches between two switching states, resulting in the two rectangular output signals S1, S2, which are phase-shifted by 90° from each other. Switching between the two switching states occurs when a defined magnetic field threshold value is exceeded or undershot, which is defined in the region of the zero crossing of the curves of the magnetic flux densities S1, S2. The phase shift of the output signals S1, S2 corresponds to the phase shift required to control the two windings 20, 22. The output signals S1, S2 of the two-axis Hall switch 53 can therefore be used unchanged or almost unchanged to control the two windings 20, 22. This creates a direct link between the position of the rotor 40 and the control of the windings 20, 22.

[0033] The spindle gear 60 has a spindle nut 62 and a spindle rod 64. The spindle nut 62 is arranged in a receiving opening 42 provided on the rotor 40 and is firmly connected to the rotor. The spindle nut 62 has an internal thread that engages an external thread of the spindle nut 62.

[0034] At an axial end of the spindle rod 64 facing away from the rotor 40, a valve body 66 is arranged on the spindle rod 64, which cooperates with a valve seat 68 which is formed on the housing 11 and onto which the valve body 66 is placed when the rotor 40 rotates or from which the valve body 66 is lifted off, so that a precise control of a free flow cross-section between the valve seat 68 and the valve body 66 takes place depending on the rotational position of the rotor 40.

[0035] Thus, an electric motor 12 for a positioning or conveying device of a motor vehicle is provided, in which the phase-shifted control of the two windings 20, 22 can be carried out in a simple, reliable, space-saving and cost-effective manner.

[0036] It should be clear that the scope of the main claim is not limited to the described embodiment, but various modifications are possible. For example, the multi-axis Hall element 52 can be designed differently.

Claims

1. Electric motor for a positioning or pumping device of a motor vehicle, with a stator (14) having a first winding (20) and a second winding (22), wherein the second winding (22) and the first winding (20) can be controlled independently from one another, a rotor (40) which magnetically interacts with the magnetic fields produced by energization of the windings (20, 22), and a sensor device (50) for detecting the position of the rotor (40), wherein the sensor device (50) comprises a multi-axis Hall element (52) with two output signals (S1, S2), wherein each output signal (S1, S2) is assigned to a respective axis (A1, A2) such that magnetic field lines oriented in the direction of the axes (S1, S2) and the associated magnetic flux density are measured and the measured magnetic flux density and thus the output signals (S1, S2) change as a function of the rotor position, wherein the first output signal (S1) associated with the first axis (A1) is phase-shifted with respect to the second output signal (S2) associated with the second axis (A2), wherein the first winding (20) can be driven by using the first output signal (S1) and the second winding (22) can be driven by using the second output signal (S2), characterized in that the stator (14) is a claw pole stator, wherein the claw pole stator comprises two claw pole stator elements (16, 18) which are arranged axially next to one another and each comprise a winding (20, 22) and a claw pole sheet metal pair (24, 26), and wherein a first claw pole stator element (16, 18) is arranged electrically twisted by 90° to a second claw pole stator element (16, 18) around an axial axis of the stator (14).

2. Electric motor according to claim 1, characterized in that the magnetic poles associated with the first winding (20) are electrically twisted with respect to the magnetic poles associated with the second winding (22), wherein the phase shift between the two output signals (S1, S2) of the multi-axis Hall element (52) is identical to the electrical twist between the two the two magnetic poles associated with the two windings (20, 22).

3. Electric motor according to claim 2, characterized in that the magnetic poles associated with the first winding (20) are arranged so as to be electrically offset through 90° with respect to the magnetic poles associated with the second winding (22).

4. Electric motor according to claim 2 or 3, characterized in that the magnetic poles associated with the first winding (20) are mechanically offset around an angle = 90° / number of pole pairs with respect to the magnetic poles associated with the second winding (22).

5. Electric motor according to one of the preceding claims, characterized in that the multi-axis Hall element (52) is a multi-axis Hall switch (53), wherein the multi-axis Hall switch (53) can be switched to a first switching state when a magnetic field threshold value is exceeded and can be switched to a second switching state when the magnetic field is below the threshold value.

6. Electric motor according to one of the preceding claims, characterized in that the rotor (40) comprises a plurality of permanent magnets or a plurality of permanently magnetized regions.

7. Electric motor according to claim 6, characterized in that the multi-axis Hall element (52) for measuring the angle of rotation of the rotor (40) interacts with the permanent magnets or the magnetized regions of the rotor (40), wherein the rotor (40) projects axially out of the stator (14), wherein the multi-axis Hall element (52) is arranged on a projecting portion of the rotor (40).

8. Electric motor according to one of the preceding claims, characterized in that the multi-axis Hall element (52) is a two-axis Hall element or a three-axis Hall element.

9. Electric motor according to claim 1, characterized in that both claw pole sheets (28, 30, 32, 34) of a pair of claw pole sheets (24, 26) each comprise eight claws (38) and the rotor (40) is configured as a 16-pole rotor.