Excitation type series excitation linear motor

Abstract

The utility model relates to motor technical field especially relates to a kind of excitation type series excitation linear motor, including shell and its inside stator coil and motional coil and the drive shaft axially slidingly connected in shell. Limiting piece that shell is equipped with limit the circumferential movement of drive shaft, the first end of drive shaft is connected with motional coil by penetrating into shell interior, and the second end of drive shaft penetrates out shell exterior. Stator coil is set in the outside of motional coil, and there is air gap between the two, and the series excitation mode connection between the two, the excitation magnetic field coupling between stator coil and motional coil makes motional coil drive shaft linear motion, compared with the existing permanent magnet linear motor, no longer rely on permanent magnet to form magnetic field, effectively reduce the manufacturing cost of motor, avoid the assembly and failure problem related with permanent magnet, and with high thrust density, application range is wider, especially can be applied to the field such as needleless injection and electromagnetic riveting of higher thrust intensity requirement.

Description

Technical Field

[0001] This utility model relates to the field of motor technology, and in particular to an excitation-type series-wound linear motor. Background Technology

[0002] Traditional synchronous linear motors are generally permanent magnet synchronous linear motors, relying on permanent magnets on the mover or stator to generate a magnetic field. While they offer high efficiency and thrust density, they also have several drawbacks. For example, permanent magnets are expensive and their prices fluctuate greatly, leading to a higher overall motor cost. Furthermore, permanent magnets are prone to demagnetization at high temperatures (>150℃) or in reverse magnetic fields, limiting their application in harsh environments (such as metallurgy and chemical industries). Additionally, the permanent magnets require precise installation to avoid magnetic field unevenness, increasing assembly complexity. Some motors, such as induction linear motors, use a permanent magnet-free design. While this reduces costs, it results in lower efficiency due to slip losses and insufficient thrust density.

[0003] Therefore, there is an urgent need for a linear motor that can combine high thrust with low cost. Utility Model Content

[0004] (a) Technical problems to be solved

[0005] In view of the above-mentioned shortcomings and deficiencies of the prior art, this utility model provides an excitation-type series-wound linear motor, which solves the technical problems of high cost and complex assembly of traditional linear motors with permanent magnets, and low efficiency and insufficient thrust of linear motors without permanent magnets.

[0006] (II) Technical Solution

[0007] To achieve the above objectives, the main technical solutions adopted by this utility model include:

[0008] In a first aspect, this utility model provides an excitation-type series-wound linear motor, including a housing, a stator coil and a mover coil disposed inside the housing, and a drive shaft axially slidably connected to the housing. The housing is provided with a limiting member to restrict the circumferential movement of the drive shaft. The first end of the drive shaft passes through the inside of the housing and is connected to the mover coil, and the second end of the drive shaft passes through the outside of the housing.

[0009] The stator coil is sleeved outside the mover coil, with an air gap between them. The stator coil and the mover coil are connected in series. The excitation magnetic field coupling between the stator coil and the mover coil causes the mover coil to drive the drive shaft to move linearly along the axial direction.

[0010] Optionally, the stator coils are set with N+1 groups, the mover coils are set with N groups, and the stator coils, mover coils and drive shaft are all arranged coaxially.

[0011] Optionally, a stator coil support is fixedly connected inside the housing, and the stator coil is wound on the stator coil support. A mover core is fixedly connected to the first end of the drive shaft, and a groove is provided on the outer wall of the mover core in the circumferential direction, and the mover coil is wound on the groove.

[0012] Optionally, the Nth group of moving coils is positioned at the midpoint of the axial direction of the Nth group of stator coils and the N+1th group of stator coils, forming an I-shaped structure together, and the winding directions of adjacent groups of stator coils are opposite.

[0013] Optionally, the moving coil and the stator coils on both sides are partially overlapped in the axial direction, with the overlap distance being 1 / 2 to 1 / 3 of the winding length of the moving coil, so that the side of the stator coil closer to the moving coil can be within the magnetic field lines of the moving coil.

[0014] Optionally, the housing includes a bushing, which is fitted onto the drive shaft, and the housing is axially slidably connected to the drive shaft through the bushing.

[0015] Optionally, the limiting element is a key disposed between the bushing and the drive shaft, or an external spline is disposed on the outer surface of the drive shaft and an internal spline is disposed on the inner surface of the bushing to limit the circumferential movement of the drive shaft within the bushing.

[0016] Optionally, the air gap between the stator coil and the mover coil is between 0.5mm and 3mm.

[0017] Optionally, a control module is provided on the outside of the housing, and a current regulating unit is provided inside the control module. The current regulating unit can adjust the direction of the current in the stator coil or the moving coil so that the moving coil drives the drive shaft to achieve reciprocating linear motion. At the same time, the current regulating unit can also adjust the magnitude of the current in the stator coil and the moving coil to control the magnitude of the thrust output by the moving coil driving the drive shaft.

[0018] (III) Beneficial Effects

[0019] The beneficial effects of this utility model are:

[0020] This invention discloses a series-excited linear motor. By using the excitation magnetic field coupling between the stator and mover coils, the mover coil drives the drive shaft to move linearly along the axial direction. Compared to existing permanent magnet linear motors, it eliminates the need for traditional permanent magnets to generate the magnetic field, effectively reducing manufacturing costs and avoiding a series of assembly and failure problems associated with permanent magnets. Compared to existing induction linear motors, it maintains lower costs while avoiding the low efficiency caused by slip losses. Furthermore, this invention arranges the stator and mover coils coaxially, using N+1 groups in combination with N groups, fully utilizing the magnetic lines of force on both sides of the mover coil. Therefore, this synchronously excited linear motor has high thrust density and a wider range of applications, especially in fields requiring high thrust strength, such as needle-free injection and electromagnetic riveting. Attached Figure Description

[0021] Figure 1 This is a cross-sectional view of Embodiment 1 of the excitation-type series-excited linear motor of this utility model;

[0022] Figure 2 for Figure 1 The commutation principle diagram of a linear motor.

[0023] [Explanation of Labels in the Attached Image]

[0024] 1: Outer casing; 11: Stator coil support; 12: Bushing;

[0025] 2: Stator coil;

[0026] 3: Moving coil;

[0027] 4: Drive shaft; 41: First end; 42: Second end; 43: Moving core; 44: Groove;

[0028] 5: Limiting components;

[0029] 6: Control module;

[0030] 7: Current regulating unit;

[0031] 8: Position detection unit;

[0032] 9: Calculation unit;

[0033] L1: Stator coil; L2: Moving coil; S1: Switch 1; S2: Switch 2; S3: Switch 3; S4: Switch 4. Detailed Implementation

[0034] To better explain and facilitate understanding of this utility model, a detailed description of its specific embodiments is provided below with reference to the accompanying drawings. In this document, directional terms such as "upper," "lower," "left," and "right" are used interchangeably. Figure 1 The orientation is used as a reference.

[0035] This invention discloses a series-excited linear motor that uses the coupling of the excitation magnetic field between the stator coil and the mover coil to drive the drive shaft in axial linear motion. Compared to existing permanent magnet linear motors, it eliminates the need for traditional permanent magnets to form a magnetic field, effectively reducing manufacturing costs and avoiding a series of assembly and failure problems associated with permanent magnets. Compared to existing induction linear motors, it maintains lower costs while avoiding low efficiency due to slip losses. Furthermore, this linear motor arranges the stator and mover coils coaxially and uses N+1 sets in combination with N sets, fully utilizing the magnetic lines of force on both sides of the mover coil. Therefore, this synchronously excited linear motor has high thrust density and a wider range of applications, especially in fields requiring high thrust strength, such as needle-free injection and electromagnetic riveting.

[0036] To better understand the above technical solutions, exemplary embodiments of the present invention will be described in more detail below with reference to the accompanying drawings. Although exemplary embodiments of the present invention are shown in the drawings, it should be understood that the present invention can be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided so that the present invention can be understood more clearly and thoroughly, and that the scope of the present invention can be fully conveyed to those skilled in the art.

[0037] Example 1:

[0038] Reference Figure 1 This embodiment proposes an excitation-type series-wound linear motor, including a housing 1, a stator coil support 11, a stator coil 2, a mover core 43, a mover coil 3 disposed inside the housing 1, and a drive shaft 4 axially slidably connected to the housing 1.

[0039] The stator coil support 11 is positioned close to the inner wall of the outer casing 1 and is fixedly connected to the outer casing 1. The stator coil 2 is wound around the stator coil support 11. The drive shaft 4 is located in the radial center region of the outer casing 1 and has a first end 41 and a second end 42. The first end 41 penetrates into the interior of the outer casing 1 and is connected to the mover coil 3 through the mover core 43. The mover core 43 is fixedly connected to the first end 41, and a groove 44 is provided on the circumferential outer wall of the mover core 43. The mover coil 3 is wound around the groove 44. The second end 42 of the drive shaft 4 protrudes from the outside of the outer casing 1 to output thrust. The stator coil 2, the mover coil 3, and the drive shaft 4 are all arranged coaxially. The stator coil 2 is entirely sleeved on the outside of the mover coil 3, with an air gap between them. The size of the air gap is preferably set between 0.5mm and 3mm. A smaller air gap can effectively reduce the magnetic circuit reluctance, increase the air gap magnetic flux density, suppress end leakage magnetic flux, improve magnetic field utilization, and thus reduce the excitation current and increase the thrust. Furthermore, the stator coil 2 and the moving coil 3 are connected in a series excitation manner. Through the magnetic field coupling between the stator coil 2 and the moving coil 3, the moving coil 3 drives the drive shaft 4 to move linearly along the axial direction. The thrust of a traditional linear motor is directly proportional to the current. However, the series excitation connection method used in this embodiment can make the thrust directly proportional to the square of the current, so that a larger thrust can be output when the same amount of input current is used.

[0040] Meanwhile, the outer shell 1 and the mover core 43 are both made of iron with high magnetic permeability to provide high magnetic permeability; the stator coil support 11 is made of plastic, ceramic or composite material with extremely low magnetic permeability to ensure that eddy current loss and hysteresis loss are reduced, while providing mechanical support. This material selection can play a better role in correcting the direction of magnetic lines of force, so as to improve the utilization rate of magnetic energy and obtain higher thrust.

[0041] A bushing 12 is provided near the drive shaft 4 on the outer casing 1. The outer peripheral wall of the bushing 12 is fixedly connected to the outer casing 1, and the inner hole of the bushing 12 is fitted onto the drive shaft 4. The outer casing 1 is axially slidably connected to the drive shaft 4 through the bushing 12. To prevent the drive shaft 4 from rotating circumferentially, a key is provided between the bushing 12 and the drive shaft 4. Multiple sets of this key can be provided along the circumferential direction, or an external spline can be provided on the outer surface of the drive shaft 4 and an internal spline can be provided on the inner surface of the bushing 12 to restrict the circumferential movement of the drive shaft 4 within the bushing 12.

[0042] Furthermore, to increase the thrust output of the linear motor, this embodiment sets the number of stator coils 2 to N+1 groups and the number of mover coils 3 to N groups. The Nth group of mover coils 3 is positioned at the midpoint of the axial direction of the Nth group of stator coils 2 and the N+1th group of stator coils 2, forming an I-shaped structure, with adjacent groups of stator coils 2 wound in opposite directions. Simultaneously, the mover coil 3 partially overlaps with the stator coils 2 on both sides in the axial direction, with an overlap distance of 1 / 2 to 1 / 3 of the winding length of the mover coil 3, ensuring that the side of the stator coil 2 closest to the mover coil 3 is within the magnetic field lines of the mover coil 3. The value of N ranges from 1 to 100 to balance various factors such as electromagnetic force requirements, thermal performance, installation space, and cost. This partially overlapping I-shaped arrangement results in a more compact overall structure and a more compact magnetic circuit. It not only fully utilizes the magnetic field lines on both sides of the mover coil 3 but also allows it to operate beyond its limits without being limited by the saturation magnetic induction intensity of the mover core 43. Traditional linear motors typically rely on an iron core for magnetic conduction, with no direct interaction between the mover and stator. Therefore, once the iron core reaches saturation, the magnetic energy generated by the mover / stator cannot be fully utilized (the saturation magnetic induction of pure iron is approximately 2.15 Tesla). Consequently, traditional linear motors can output relatively small thrust for the same volume. However, in the linear motor proposed in this embodiment, when the mover iron core 43 reaches saturation, the stator coil 2 remains within the magnetic field lines of the mover coil 3. Therefore, the magnetic fields between the two continue to interact, resulting in a greater thrust output.

[0043] The following example compares the linear motor in this embodiment with a traditional linear motor:

[0044] Comparison of magnetic field strength:

[0045] The air gap magnetic field strength of a typical electric motor (which is close to or slightly smaller than the magnetic field strength inside the coil) is usually between a few amperes per meter and tens of amperes per meter. For example, the air gap magnetic field strength of an AC asynchronous motor is usually in the range of 5-50 A / m; the magnetic field strength of a high-frequency motor may reach 5 A / m or higher; and permanent magnet motors, especially those using neodymium iron boron rare earth magnets, can have a magnetic field strength of 40 A / m or higher to increase power output.

[0046] It is important to note the following: First, some literature uses terms ranging from a few tenths to a few tesla to describe magnetic field strength, which is inaccurate. The unit of magnetic field strength is A / m, not tesla, which refers to magnetic flux density. Second, the maximum magnetic field strength of a typical motor generally corresponds to the saturation magnetic flux density of the iron core. Further increasing this value will lead to oversaturation, drastically reducing efficiency and increasing heat generation.

[0047] The magnetic field strength of the linear motor in this embodiment is as follows (taking the moving coil as an example):

[0048] The calculation was performed according to the magnetic field strength formula, with the preferred coil turns being 72, the current being 250A, and the coil length being 0.03m.

[0049] H=N*I / L=72*250 / 0.03=600000A / m;

[0050] Where: H is the magnetic field strength, in A / m; N is the number of coil turns; I is the current, in A; and L is the coil length, in m.

[0051] Therefore, the magnetic field strength of the linear motor shown in this embodiment is much higher than that of a traditional linear motor.

[0052] Comparison of thrust and weight:

[0053] A certain voice coil motor on the market has a maximum thrust of 1351N and a motor weight of 8825g. The linear motor shown in this embodiment, with the same output thrust, weighs less than 1000g. Therefore, the linear motor shown in this embodiment weighs only about 1 / 10 of the ordinary voice coil motor on the market.

[0054] Furthermore, a control module 6 is also provided outside the outer casing 1. This control module 6 includes a current adjustment unit 7, a position detection unit 8, and a calculation unit 9, which are electrically connected. In this embodiment, the adjustment unit 7 and the calculation unit 9 (the calculation unit 9 is, for example, a microprocessor, a drive control board, etc.) are integrated within the control module 6. The current adjustment unit 7 can adjust the magnitude and direction of the current in the coil through a physical processing circuit. The calculation unit 9 can calculate the specific value of the required current based on the position information and the target thrust value. Both of these are achievable with existing technology. The following description of the control is to facilitate those skilled in the art to better understand the working process of the linear motor shown in this embodiment.

[0055] The current regulating unit 7 can adjust the direction of the current in the stator coil 2 or the moving coil 3, so that the moving coil 3 drives the drive shaft 4 to achieve reciprocating linear motion. Simultaneously, the current regulating unit 7 can also adjust the magnitude of the current in the stator coil 2 and the moving coil 3 to control the magnitude of the thrust output by the moving coil 3 driving the drive shaft 4. Figure 2The diagram illustrates the principle of commutation achieved by changing the direction of current in the moving coil 3. When control switches S1 and S4 are closed, the current direction in the moving coil 3 is from top to bottom; when control switches S2 and S3 are closed, the current direction in the moving coil 3 is from bottom to top. Therefore, by controlling the closure of different switches, the direction of current in the moving coil 3 can be adjusted. The method of changing the current direction in the stator coil 2 is similar to that of changing the current direction in the moving coil 3, and will not be described in detail here.

[0056] The position detection unit 8 can detect the position information of the moving coil 3 in real time. Preferably, the position information of the moving coil 3 in a specified area can be collected in real time by means of a grating ruler, a magnetic encoder or a laser displacement sensor.

[0057] The calculation unit 9 can calculate the direction and magnitude of the required current based on the target thrust value and the position information of the moving coil 3 provided by the position detection unit 8, and feed it back to the current adjustment unit 7 for adjustment.

[0058] The synchronous excitation linear motor shown in this embodiment has a simple structure, is easy to assemble, and does not have a traditional permanent magnet structure, resulting in low cost. It also avoids a series of assembly and failure problems associated with permanent magnets. At the same time, through the combined effect of the coil arrangement, the number of coils, and the series excitation connection method, the electromagnetic utilization rate is greatly improved, giving it a high thrust density. Compared with traditional linear motors, it can reduce the volume to about 1 / 10 while maintaining the same thrust, making it more widely applicable, especially in fields such as needleless injection and electromagnetic riveting where high thrust strength is required.

[0059] In the description of this utility model, it should be understood that the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this utility model, "a plurality of" means two or more, unless otherwise explicitly specified.

[0060] In this utility model, unless otherwise explicitly specified and limited, the terms "installation," "connection," "joining," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. For those skilled in the art, the specific meaning of the above terms in this utility model can be understood according to the specific circumstances.

[0061] In this utility model, unless otherwise explicitly specified and limited, "above" or "below" the second feature can mean that the first feature is in direct contact with the second feature, or that the first feature is in indirect contact with the second feature through an intermediate medium. Furthermore, "above," "on top of," and "over" the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "beneath" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0062] In the description of this specification, the terms "one embodiment," "some embodiments," "embodiment," "example," "specific example," or "some examples," etc., refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example, which are included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0063] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make modifications, alterations, substitutions and variations to the above embodiments within the scope of the present invention.

Claims

1. An excitation-type series-wound linear motor, characterized in that, It includes a housing (1), a stator coil (2) and a mover coil (3) disposed inside the housing (1), and a drive shaft (4) axially slidably connected to the housing (1); The outer casing (1) is provided with a limiting member (5) to restrict the circumferential movement of the drive shaft (4); The first end (41) of the drive shaft (4) passes into the interior of the housing (1) and is connected to the moving coil (3), and the second end (42) of the drive shaft (4) passes out of the exterior of the housing (1); The stator coil (2) is sleeved on the outside of the moving coil (3), and there is an air gap between them. The stator coil (2) and the moving coil (3) are connected in series. The excitation magnetic field coupling between the stator coil (2) and the moving coil (3) causes the moving coil (3) to drive the drive shaft (4) to move linearly along the axial direction.

2. The excitation-type series-wound linear motor as described in claim 1, characterized in that, The stator coil (2) is provided in N+1 groups, the moving coil (3) is provided in N groups, and the stator coil (2), the moving coil (3) and the drive shaft (4) are all arranged coaxially.

3. The excitation-type series-wound linear motor as described in claim 2, characterized in that, A stator coil bracket (11) is fixedly connected inside the outer casing (1), and the stator coil (2) is wound on the stator coil bracket (11); A moving core (43) is fixedly connected to the first end (41) of the drive shaft (4). A groove (44) is provided on the outer wall of the moving core (43) in the circumferential direction. The moving coil (3) is wound on the groove (44).

4. The excitation-type series-wound linear motor as described in claim 2, characterized in that, The moving coil (3) of the Nth group is located at the middle position of the stator coil (2) of the Nth group and the stator coil (2) of the N+1th group, forming an I-shaped structure together, and the winding directions of the stator coils (2) of adjacent groups are opposite.

5. The excitation-type series-wound linear motor as described in claim 4, characterized in that, The moving coil (3) and the stator coils (2) on both sides are partially overlapped in the axial direction. The overlap distance is 1 / 2 to 1 / 3 of the winding length of the moving coil (3), so that the side of the stator coil (2) closer to the moving coil (3) can be within the magnetic field line range of the moving coil (3).

6. The excitation-type series-wound linear motor as described in claim 1, characterized in that, The outer casing (1) includes a bushing (12), which is sleeved on the drive shaft (4). The outer casing (1) is axially slidably connected to the drive shaft (4) through the bushing (12).

7. The excitation-type series-wound linear motor as described in claim 6, characterized in that, The limiting member (5) is a key disposed between the bushing (12) and the drive shaft (4); Alternatively, an external spline may be provided on the outer surface of the drive shaft (4), and an internal spline may be provided on the inner surface of the bushing (12); To restrict the circumferential movement of the drive shaft (4) within the bushing (12).

8. The excitation-type series-wound linear motor as described in claim 1, characterized in that, The air gap between the stator coil (2) and the moving coil (3) is between 0.5 mm and 3 mm.

9. The excitation-type series-wound linear motor as described in claim 1, characterized in that, The outer casing (1) is provided with a control module (6), and the control module (6) is provided with a current adjustment unit (7). The current adjustment unit (7) can adjust the direction of the current in the stator coil (2) or the moving coil (3) so that the moving coil (3) drives the drive shaft (4) to achieve reciprocating linear motion. At the same time, the current adjustment unit (7) can also adjust the magnitude of the current in the stator coil (2) and the moving coil (3) to control the magnitude of the thrust output by the moving coil (3) driving the drive shaft (4).

10. The excitation-type series-wound linear motor as described in claim 9, characterized in that: The control module (6) further includes a position detection unit (8) and a calculation unit (9); The position detection unit (8) is used to detect the position information of the moving coil (3); The calculation unit (9) is used to calculate the magnitude and direction of the required current and feed it back to the current adjustment unit (7); The current regulating unit (7), the detection unit (8), and the calculation unit (9) are electrically connected.

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