A multi-pole magnetic circuit friction brake without axial magnetic leakage

Abstract

This invention discloses a multi-pole magnetic circuit friction brake with zero axial leakage flux, comprising a rotor, a pressure plate, an armature, and a stator. A spring and an air gap are provided between the armature and the stator. A multi-pole solenoid coil is embedded within the stator, and the multi-pole solenoid coil consists of several groups of solenoid coils. Each group of solenoid coils has the same structure and is uniformly distributed in the circumferential direction, and the current directions of adjacent groups of solenoid coils are opposite, forming a pair of poles. This invention uses multi-pole solenoid coils, and the axial leakage flux generated by the multi-pole solenoid coils cancels out due to the opposite phases, resulting in a zero-leakage flux effect along the axial direction. This avoids the reduced accuracy of axially mounted magnetic encoders caused by axial leakage flux in traditional brakes.

Description

Technical Field

[0001] This invention relates to the field of electromagnetic brake technology, specifically to a multi-pole magnetic circuit friction brake with no axial leakage magnetic flux. Background Technology

[0002] To achieve power-off retention, servo motors require a brake mounted on the motor shaft; a common type is the electromagnetic friction brake. Existing electromagnetic friction brakes consist of a rotor, pressure plate, armature, and stator. The stator contains an embedded unipolar solenoid coil, and a spring and air gap are placed between the armature and the stator. When the brake is energized, the unipolar solenoid coil generates a magnetic field, causing the armature to overcome the spring force and engage with the stator, allowing the rotor to rotate freely. When the brake is de-energized, the armature, under the spring force, presses the rotor firmly against the pressure plate, achieving braking.

[0003] The armature 4, stator 2, and unipolar solenoid coil 3 constitute the main magnetic circuit of the brake. (See also...) Figure 1 The main magnetic flux 5 generated by the unipolar solenoid coil 3 forms a closed loop through the inner stator ring 21, armature 4, and outer stator ring 22. The main magnetic flux 5 is radially distributed in the armature 4, and its direction varies depending on the polarity of the brake connection. In addition to the main magnetic circuit, the unipolar solenoid coil 3 also generates axial leakage flux 6, see [reference needed]. Figure 2 The leakage flux 6 is axially distributed in the inner hole of the brake and transmitted to the shaft end along the main shaft where the brake is installed. An encoder is installed at the end of the servo motor rotor shaft to measure angle and speed as a feedback element. If a magnetic encoder is installed at the shaft end, the leakage flux of the brake will affect the operating point of the encoder. Especially when the brake is randomly wired in both directions, the axial leakage flux generated by the brake is random, which seriously affects the accuracy of the magnetic encoder. Summary of the Invention

[0004] To solve the above-mentioned technical problems, the present invention provides a multi-pole magnetic circuit friction brake with no axial leakage magnetic flux.

[0005] The technical solution adopted in this invention is:

[0006] A multi-pole magnetic circuit friction brake with no axial leakage flux includes a rotor, a pressure plate, an armature, and a stator. A spring and an air gap are provided between the armature and the stator. A multi-pole solenoid coil is embedded in the stator. The multi-pole solenoid coil is composed of several groups of solenoid coils. Each group of solenoid coils has the same structure and is evenly distributed in the circumferential direction. The current directions of two adjacent groups of solenoid coils are opposite, forming a pair of poles.

[0007] Furthermore, each set of solenoid coils includes at least one unipolar solenoid coil.

[0008] Furthermore, the cross-sectional shape of the unipolar solenoid coil is circular, elliptical, trapezoidal, or polygonal.

[0009] Furthermore, an annular groove is provided inside the stator, and several protruding iron cores are provided inside the annular groove. The unipolar solenoid coil is embedded in the annular groove and fitted on the protruding iron cores.

[0010] Furthermore, the cross-sectional shape of the raised iron core is adapted to the cross-section of the unipolar solenoid coil.

[0011] Furthermore, the stator is made of a non-magnetic metal material, while the raised iron core is made of a magnetic metal material.

[0012] Furthermore, the raised iron core is embedded in the annular groove of the stator during casting.

[0013] The beneficial effects of this invention are:

[0014] 1. This invention uses a multipolar solenoid coil. The axial leakage flux generated by the multipolar solenoid coil cancels out due to the positive and negative phases, resulting in a zero-leakage magnetic flux effect along the axial direction. This avoids the reduction in accuracy of axially mounted magnetic encoders caused by axial leakage flux in traditional brakes.

[0015] 2. This invention employs a stator made of non-magnetic metal material and a raised iron core made of magnetic metal material. The main magnetic circuit structure generated by the multi-polar solenoid coils mounted on the raised iron core changes the magnetic circuit direction in the traditional armature. The main magnetic flux generated by one set of solenoid coils passes through the raised iron cores and armatures of that set and enters the raised iron cores of another adjacent set, forming a closed loop. The stator made of non-magnetic metal material no longer serves as the main magnetic circuit, but only plays the role of mounting and protecting the internal coils. Less leakage magnetic flux is generated in the coils, further improving the accuracy of the axially mounted magnetic encoder. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the main magnetic circuit of an existing brake.

[0017] Figure 2 This is a schematic diagram of the leakage magnetic circuit of an existing brake.

[0018] Figure 3 This is a three-dimensional structural schematic diagram of the brake according to Embodiment 1 of the present invention.

[0019] Figure 4 This is a schematic diagram of the leakage magnetic circuit structure of the brake in Embodiment 1 of the present invention.

[0020] Figure 5 This is a schematic diagram of the main magnetic circuit structure of the brake in Embodiment 2 of the present invention.

[0021] Figure 6This is a schematic diagram of the stator structure of the brake according to Embodiment 3 of the present invention.

[0022] Figure 7 This is a schematic diagram of the stator structure of the brake according to Embodiment 4 of the present invention.

[0023] Figure 8 This is a schematic diagram of the stator structure of the brake according to Embodiment 5 of the present invention. Detailed Implementation

[0024] The present invention will be further illustrated below with specific examples to facilitate understanding of the invention, but this does not limit the invention.

[0025] Example 1

[0026] See Figure 3 and Figure 4 This embodiment provides a multi-pole magnetic circuit friction brake without axial leakage magnetic flux, including a rotor 11, a pressure plate 15, an armature 14 and a stator 12. A spring and an air gap (not shown in the figure) are provided between the armature 14 and the stator 12. The stator 12 is made of a conventional magnetic conductive metal material. An annular groove is provided in the stator 12. Eight circumferentially evenly distributed protruding iron cores 123 are provided in the annular groove. The protruding iron cores 123 are formed by axially protruding outward from the bottom surface of the annular groove.

[0027] Eight unipolar solenoid coils 16 with elliptical cross-sections are embedded in the annular groove. The current in two adjacent sets of solenoid coils is in opposite directions, forming a pair of poles.

[0028] The main magnetic flux generated by the 8 unipolar solenoid coils 16 forms a closed loop through the inner stator ring 122, armature 14, and outer stator ring 121. The leakage magnetic flux 13 generated by the 8 unipolar solenoid coils 16 is axially distributed in the inner hole of the brake, and the positive and negative phases cancel each other out.

[0029] Example 2

[0030] See Figure 5 The structure of the multi-pole magnetic circuit friction brake without axial leakage flux in this embodiment is basically the same as that in Embodiment 1, except that the stator 22 is made of non-magnetic metal material and the raised iron core 223 is made of magnetic metal material. The raised iron core 223 is embedded in the annular groove of the stator 22 during casting.

[0031] The main magnetic flux 23 generated by the eight unipolar solenoid coils 16 is distributed circumferentially, flowing from one raised iron core 223 to another, forming a closed loop. The stator outer ring 221 and stator inner ring 222, made of non-magnetic metal material, no longer serve as the main magnetic circuit, but only function to install and protect the internal coils. The very small amount of leakage magnetic flux generated by the eight unipolar solenoid coils 16 is axially distributed in the inner hole of the brake, and the positive and negative phases cancel each other out.

[0032] Example 3

[0033] See Figure 6 The structure of the multi-pole magnetic circuit friction brake without axial leakage flux in this embodiment is basically the same as that in Embodiment 1, except that the cross-sectional shape of the unipolar solenoid coil 36 is circular. In this embodiment, the stator can also be made of non-magnetic metal material, and the raised iron core can be made of magnetic metal material.

[0034] Example 4

[0035] See Figure 7 The structure of the multi-pole magnetic circuit friction brake without axial leakage flux in this embodiment is basically the same as that in Embodiment 1, except that the stator 42 is polygonal and the cross-sectional shape of the unipolar solenoid coil 46 is trapezoidal. In this embodiment, the stator can also be made of non-magnetic metal material, and the protruding iron core can be made of magnetic metal material.

[0036] Example 5

[0037] See Figure 8 The structure of the multi-pole magnetic circuit friction brake without axial leakage flux in this embodiment is basically the same as that in Embodiment 1. The only difference is that four sets of solenoid coils are embedded in the annular groove of the stator 52. Each set of solenoid coils includes two unipolar solenoid coils 56 with an elliptical cross-section. The current directions of adjacent sets of solenoid coils are opposite, forming a pair of poles. In this embodiment, the stator can also be made of non-magnetic metal material, and the protruding iron core can be made of magnetic metal material.

[0038] The leakage flux generated by the four sets of solenoid coils is axially distributed in the inner hole of the brake, and the positive and negative phases cancel each other out.

[0039] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications are also within the protection scope of the present invention.

Claims

1. A multi-pole magnetic circuit friction brake with no axial leakage magnetic flux, comprising a rotor, a pressure plate, an armature, and a stator, wherein a spring and an air gap are provided between the armature and the stator, characterized in that, The stator is embedded with a multipolar solenoid coil, which is composed of several groups of solenoid coils. Each group of solenoid coils has the same structure and is evenly distributed in the circumferential direction. Each group of solenoid coils includes two unipolar solenoid coils. The current directions of adjacent groups of solenoid coils are opposite, forming a pair of poles. The stator has an annular groove with several protruding iron cores inside. The unipolar solenoid coils are embedded in the annular groove and mounted on the protruding iron cores. The stator is made of non-magnetic metal material, while the raised iron core is made of magnetic metal material.

2. The multi-pole magnetic circuit friction brake with no axial leakage magnetic flux according to claim 1, characterized in that, The cross-sectional shape of a unipolar solenoid coil can be circular, elliptical, trapezoidal, or polygonal.

3. The multi-pole magnetic circuit friction brake with no axial leakage magnetic flux according to claim 1, characterized in that, The cross-sectional shape of the raised iron core is adapted to the cross-section of the unipolar solenoid coil.

4. The multi-pole magnetic circuit friction brake with no axial leakage magnetic flux according to claim 1, characterized in that, The raised iron core is embedded in the annular groove of the stator during casting.

Images