Towed cableless linear motor and position detection device for a towed cableless linear motor

Abstract

This invention relates to position detection of linear motors, and particularly to a cableless linear motor and a position detection device for cableless linear motors. The cableless linear motor includes a primary motor, a secondary motor, and a position detection device. The position detection device includes detection sensors, triggering devices, and an encoder. Multiple groups of detection sensors are arranged at intervals along the length of the linear motor on the primary motor, with each group of sensors arranged in a straight line along the length of the linear motor. Triggering devices are arranged in groups along the length of the linear motor on the secondary motor, with the distribution length of the triggering devices not less than the group spacing between adjacent groups of detection sensors. Detection sensors with the same arrangement position on each group are connected in parallel. This solution solves the problem in the prior art where the secondary motor of a linear motor requires a cable, which affects the performance of the linear motor.

Description

Technical Field

[0001] This invention relates to the position detection of linear motors, and particularly to a cableless linear motor and a position detection device for cableless linear motors. Background Technology

[0002] A linear motor consists of a primary (stator) and a secondary (mover). It can achieve linear motion directly through electromagnetic force. Compared to the linear drive method of traditional rotary motors with ball screw systems, linear motors eliminate intermediate transmission links, making them easier to maintain, faster, and more accurate in positioning, leading to their increasingly widespread applications. Currently, linear motors can be categorized into single-sided linear motors, single-sided U-shaped linear motors, double-sided U-shaped linear motors, and other structural forms.

[0003] When a linear motor is running, the linear motor system, as a typical closed-loop control system, relies heavily on its position detection device as a crucial component of the position closed loop. Currently, commonly used position detection devices include various sensors such as linear Hall effect sensors, magnetic gratings, and optical gratings. Because the primary winding of a linear motor is relatively long, while the secondary winding is often very short, these sensors are mounted on the secondary winding to achieve position detection throughout the entire stroke. Triggering devices are arranged along the length of the linear motor on the primary winding. For example, a linear motor disclosed in patent document CN214626766U includes a base, a linear guide rail on the base, and magnets arranged along the length of the linear guide rail. The magnets serve as triggering devices to activate the detection sensors. The linear guide rail houses the secondary winding (i.e., the linear actuator in the aforementioned patent document), and the secondary winding is equipped with an on-rail magnetic encoder detection device. The on-rail magnetic encoder detection device has multiple Hall effect elements spaced apart along the length of the linear guide rail. When the magnet moves with the secondary motor, it can trigger the Hall element. The Hall element works with the magnet to detect the magnetic field signal of any adjacent magnetic pole pair of the magnet where the secondary motor is located. The signal is sampled and calculated by the encoder (i.e., the microprocessor in the above patent document), converted into an angle signal, and fed back to the servo driver that drives the secondary motor to move the electrical angle position.

[0004] However, the detection sensor requires a working cable to function properly, and a signal cable is also needed to feed the signal back to the control terminal. To ensure the reliable operation of the working cable, signal cable, and other transmission cables, a trailing cable needs to be installed on the secondary winding of the motor, dragging the cable during operation. This undoubtedly increases the number of uncontrollable factors affecting the stable operation of the linear motor, and also impacts the linear motor's load capacity and operating speed. Simply swapping the positions of the detection sensor and the triggering device is not feasible due to the limited length of the motor's secondary winding, making it impossible to install a triggering device corresponding to the full stroke of the linear motor. Summary of the Invention

[0005] One objective of this invention is to provide a position detection device for a cableless linear motor, solving the problem that existing linear motors require a cable on the secondary winding, which affects the performance of the linear motor. Another objective of this invention is to provide a cableless linear motor, avoiding the impact of a cable on the secondary winding's performance.

[0006] The present invention adopts the following technical solution:

[0007] A cable-free linear motor includes a motor primary, on which a secondary motor is guided and mounted; it also includes a position detection device for detecting the position of the secondary motor on the motor primary, the position detection device including a detection sensor and a triggering device for triggering the detection sensor; multiple groups of detection sensors are arranged at intervals along the length of the linear motor on the motor primary, and the detection sensors in each group are arranged in a straight line along the length of the linear motor; the triggering devices are arranged in groups, arranged in a straight line along the length of the linear motor on the motor secondary, the distribution length of the triggering devices is not less than the group spacing between two adjacent groups of detection sensors, so that when the triggering device at the end of the arrangement direction moves away from the last detection sensor in the corresponding group of detection sensors, the triggering device at the beginning of the arrangement direction of the triggering device can trigger the detection sensor in the adjacent group of detection sensors; detection sensors with the same arrangement position on each group of detection sensors are connected in parallel, so that when the detection sensor at the corresponding position on any group of detection sensors is triggered, the corresponding transmission cable can output a signal; the position detection device also includes an encoder for processing the signals emitted by the detection sensors.

[0008] The beneficial effects of the above technical solution are that the spaced detection sensor groups and the grouped triggering devices can form a matching relationship. The distribution length of the triggering devices is not less than the group spacing between two adjacent detection sensor groups. When the triggering device at the end of the triggering device arrangement direction is far away from the last detection sensor on the corresponding group of detection sensors, the triggering device at the beginning of the triggering device arrangement direction can trigger the detection sensors in the adjacent group of detection sensors. This can meet the continuous position detection requirements, avoid signal interruption, and also help reduce the number of detection sensors, save costs, and facilitate wiring. Compared with the existing technology, it can solve the problem that the linear motor secondary needs to be equipped with a drag cable, which affects the performance of the linear motor, and the cost is low.

[0009] Furthermore, each triggering device is arranged on the same substrate to form a trigger module.

[0010] The beneficial effects of the aforementioned further defined technical solution are that it can form a modular structure, which facilitates the installation and maintenance of trigger devices, helps to ensure the arrangement accuracy of trigger devices, and thus improves the detection accuracy.

[0011] Furthermore, the center distance between two adjacent triggering devices is set according to the pole pitch of the corresponding linear motor so as to be equal to the pole pitch of the linear motor.

[0012] The beneficial effect of the above-mentioned further defined technical solution is that it facilitates the design of algorithms.

[0013] Furthermore, each set of detection sensors is arranged on a circuit board.

[0014] Furthermore: the triggering device is a magnet, and the magnetic field polarities of the ends of two adjacent magnets that are close to each other are opposite; the detection sensor is a switch-type Hall sensor.

[0015] The beneficial effects of the aforementioned further defined technical solution are that the technology of using magnets in conjunction with switch-type Hall sensors for position detection is mature, low-cost, and easy to install and debug.

[0016] A position detection device for a cableless linear motor includes detection sensors and triggering devices for triggering the detection sensors. Multiple groups of detection sensors are arranged at intervals along the length of the linear motor on the primary winding, with each group's sensors arranged in a straight line along the length of the linear motor. Triggering devices are arranged in groups along the length of the linear motor on the secondary winding, with a distribution length not less than the group spacing between adjacent groups. This arrangement ensures that when the triggering device at the end of its arrangement moves away from the last sensor in its corresponding group, the triggering device at the beginning of its arrangement can trigger the sensors in adjacent groups. Detection sensors with identical positions in each group are connected in parallel, ensuring that the corresponding transmission cables can output signals when a sensor at a corresponding position in any group is triggered. The position detection device also includes an encoder for processing the signals emitted by the detection sensors.

[0017] The beneficial effects of the above technical solution are that the spaced detection sensor groups and the grouped trigger devices can form a matching relationship. The distribution length of the trigger devices is not less than the group spacing between two adjacent detection sensor groups. When the trigger device at the end of the trigger device arrangement direction is far away from the last detection sensor on the corresponding group of detection sensors, the trigger device at the beginning of the trigger device arrangement direction can trigger the detection sensor in the adjacent group of detection sensors. This can meet the continuous position detection requirements, avoid signal interruption, and also help reduce the number of detection sensors, save costs, and facilitate wiring. Compared with the prior art, it can avoid the linear motor performance being affected by the installation of a drag cable on the secondary side of the linear motor, and the cost is lower.

[0018] Furthermore, all triggering devices are arranged on the same substrate.

[0019] The beneficial effects of the aforementioned further defined technical solution are that it can form a modular structure, which facilitates the installation and maintenance of trigger devices, helps to ensure the arrangement accuracy of trigger devices, and thus improves the detection accuracy.

[0020] Furthermore, the center distance between two adjacent triggering devices is set according to the pole pitch of the corresponding linear motor so as to be equal to the pole pitch of the linear motor.

[0021] The beneficial effect of the above-mentioned further defined technical solution is that it facilitates the design of algorithms.

[0022] Furthermore, each set of detection sensors is arranged on a circuit board.

[0023] Furthermore: the triggering device is a magnet, and the magnetic field polarities of the ends of two adjacent magnets that are close to each other are opposite; the detection sensor is a switch-type Hall sensor.

[0024] The beneficial effects of the aforementioned further defined technical solution are that the technology of using magnets in conjunction with switch-type Hall sensors for position detection is mature, low-cost, and easy to install and debug. Attached Figure Description

[0025] Figure 1 This is a schematic diagram of the structure of Embodiment 1 of the cableless linear motor in this invention;

[0026] Figure 2 yes Figure 1 A schematic diagram of the arrangement of the detection sensors on the linear motor, viewed from above.

[0027] Figure 3 This is a schematic diagram of the structure of a single detection sensor group;

[0028] Figure 4 This is a schematic diagram of the mounting structure of the magnet on the secondary winding of the motor, i.e. Figure 1 Side view of the secondary winding of the motor;

[0029] Figure 5 yes Figure 4 A top view of the trigger module;

[0030] Figure 6 yes Figure 5 Top view.

[0031] The names of the components corresponding to the corresponding reference numerals in the figure are as follows: 11. Motor primary; 12. Motor frame; 13. Primary coil; 14. Primary fastener; 21. Trigger device; 22. Trigger base; 23. Bolt hole; 31. Motor secondary; 32. Secondary base; 33. Permanent magnet; 34. Module fastener; 41. Detection sensor; 42. Circuit board; 43. Transmission cable; 44. Encoder. Detailed Implementation

[0032] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only for explaining the invention and are not intended to limit the invention; that is, the described embodiments are merely some embodiments of the invention, not all embodiments. The components of the embodiments of the invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0033] Therefore, the following detailed description of the embodiments of the invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the invention without inventive effort are within the scope of protection of the invention.

[0034] It should be noted that, in specific embodiments of the present invention, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any actual relationship or order between these entities or operations. Furthermore, terms such as "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, the use of phrases such as "comprising a…" to define an element does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0035] In the description of this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linkage" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; 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, or they can refer to the internal connection of two components. Those skilled in the art will understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0036] In the description of this invention, unless otherwise explicitly specified and limited, the term "provided with" should be interpreted broadly. For example, the object "provided with" can be a part of the body, or it can be separately arranged from the body and connected to the body. This connection can be a detachable connection or a non-detachable connection. Those skilled in the art can understand the specific meaning of the above terms in this invention through specific circumstances.

[0037] The present invention will be further described in detail below with reference to embodiments.

[0038] Example 1 of the cableless linear motor in this invention:

[0039] like Figure 1 As shown, the cableless linear motor in this embodiment is a permanent magnet motor. The primary motor 11 adopts a double-sided U-shaped structure, including a U-shaped motor frame 12, which forms the primary base. The primary coil 13 is located on both sides of the U-shaped groove formed by the motor frame 12 and is fixed to the two sides of the U-shaped groove using primary fasteners 14. The secondary motor 31 is located in the U-shaped groove and is guided and assembled on the primary base of the primary motor 11. It includes a secondary base 32 and permanent magnets 33 located on both sides of the secondary base 32 in the horizontal direction. The permanent magnets 33 interact with the magnetic field generated by the primary motor 11 to realize the movement of the secondary motor 31. The above structure is prior art and will not be described in detail here.

[0040] like Figure 1 and Figure 2 A detection sensor 41 is installed on the bottom wall of the "U"-shaped groove. The detection sensor 41 is a switch-type Hall sensor. The detection sensors 41 are arranged in groups, and each group of detection sensors is soldered and integrated onto a circuit board 42. The circuit board 42 also has resistors, capacitors, etc., that are compatible with the switch-type Hall sensors, and cable connectors at both ends, forming a sensor integrated circuit board. The detection sensors 41 in each group are arranged in a straight line along the length of the linear motor, such as... Figure 3 The spacing between the detection sensors 41 determines the accuracy of the position signal; the larger the spacing, the lower the accuracy. The detection sensors are arranged at intervals along the length of the linear motor. Adjacent groups of sensors are connected in series via transmission cables 43. This series connection is the overall mechanical arrangement. In terms of circuit structure, the sensors 41 in the same position on each group are connected in parallel, ensuring that the corresponding transmission cable 43 outputs a signal when the sensor 41 at the corresponding position on any group is triggered. The transmission cable 43 is a flexible cable, fixed to the bottom of a U-shaped groove with cable fasteners to prevent interference with the motor secondary winding 31. The number of detection sensor groups 41 depends on the length of the linear motor and can be adjusted as needed. The corresponding triggering device 21 can also be adjusted as needed, resulting in high versatility.

[0041] like Figure 2The starting end of circuit board 42 is connected to encoder 44 via transmission cable 43. Encoder 44 consists of an embedded processor and supporting circuitry, and includes filtering and isolation circuitry to process the periodically changing pulse signals emitted by the switch-type Hall sensors, converting them into encoder signals common to motor control. These signals are then connected to the linear motor controller via another cable and sent to the controller. Encoder 44 also contains a power module to power the entire group of detection sensors 41. The transmission cables 43 connecting encoder 44 and circuit board 42, and between adjacent circuit boards 42, are multi-core cables of the same type. Each switch-type Hall sensor corresponds to one core, with additional cores used for sensor power supply.

[0042] like Figure 1 and Figure 4 A trigger device array is fixed to the bottom of the secondary substrate 32. The trigger devices 21 are magnets arranged in a straight line along the length of the linear motor, and the arrangement length is the same as the length of the secondary substrate 31. Specifically, as shown... Figure 5 , Figure 6 Each triggering device 21 is fixed to the same plate-shaped trigger base 22 by screws, forming a trigger module. The trigger base 22 has bolt holes 23, and the module is fixed to the bottom of the secondary base 32 through the bolt holes 23 and the module fasteners 34. Each trigger is rectangular, with the N and S poles arranged in the same direction, and the magnetic field polarities of the ends of two adjacent magnets that are close to each other are opposite. The center distance between two adjacent triggering devices 21 is adapted to the corresponding linear motor and is equal to the pole pitch of the linear motor. It is used to trigger the detection sensor 41 to generate a periodically changing pulse signal and facilitates the design of algorithms.

[0043] The distribution length of the trigger device 21 is equal to the group spacing between two adjacent sensor groups. This allows the trigger device 21 at the beginning of the group to trigger the sensor 41 in the adjacent sensor group when the trigger device 21 at the end of the arrangement direction moves away from the last sensor 41 in the corresponding group. Of course, those skilled in the art should understand that the group spacing between two adjacent sensor groups refers to the distance between the first sensor 41 at the adjacent ends of the two groups, not the center distance between the two groups, nor the distance between adjacent circuit boards 42. In other embodiments, the sensors can also be arranged at an angle, and two adjacent sensors arranged in a straight line can overlap in a direction perpendicular to the arrangement direction. Of course, since the sensors detect the magnetic field range, it is unnecessary to arrange the sensors too densely while meeting the detection requirements.

[0044] With the above design, when the secondary motor 31 moves, the detection magnet array at the bottom of the secondary motor 31 sweeps across the sensor integrated circuit board, and the movement of its magnetic field causes the switch-type Hall sensor to generate a pulse signal. The pulse signal is sent to the encoder 44 through the transmission cable 43, and the encoder 44 then sends the processed signal to the control device through the corresponding transmission cable 43. The detection magnet array is equipped with multiple magnets, and the sensor integrated circuit board is equipped with multiple switch-type Hall sensors, thereby generating a periodically changing continuous pulse signal, which can detect the position of the secondary motor 31 in real time. Traditional linear motor position detection devices require a cable to move with the secondary motor. This solution adopts a method where the detection sensor 41 is mounted on the primary mounting bracket, and the cable is also mounted on the primary motor, while the detection magnet array is mounted on the secondary motor. This eliminates the need for a cable, and the cable does not move with the secondary motor, achieving cable-free movement of the secondary motor. This solves the problem of linear motor operation being affected by cables, and is particularly suitable for high-speed linear motors.

[0045] Embodiment 2 of the cableless linear motor in this invention:

[0046] The difference between this embodiment and Embodiment 1 is that in Embodiment 1, the trigger device 21 is a magnet and the detection sensor 41 is a switch-type Hall sensor. In this embodiment, the trigger and the detection sensor 41 can also take other forms. For example, the trigger can be a grating, adapted to the optical linear encoder 44, and the optical signal can be read by the read head of the optical linear encoder 44 and converted into position information output.

[0047] Embodiment 3 of the cableless linear motor in this invention:

[0048] The difference between this embodiment and Embodiment 1 is that in Embodiment 1, the distribution length of the trigger device 21 is equal to the group spacing between two adjacent detection sensor groups. In this embodiment, the distribution length of the trigger device 21 is greater than the group spacing between two adjacent detection sensor groups. By correspondingly changing the algorithm, those skilled in the art can still obtain the position information of the motor secondary 31.

[0049] Embodiment 4 of the cableless linear motor in this invention:

[0050] The difference between this embodiment and Embodiment 1 is that in Embodiment 1, the center distance between two adjacent trigger devices 21 is equal to the pole pitch of the linear motor. In this embodiment, the center distance between two adjacent trigger devices 21 can also be unequal to the pole pitch of the linear motor, and the corresponding algorithm can be adjusted accordingly.

[0051] Embodiment 5 of the cableless linear motor in this invention:

[0052] The difference between this embodiment and Embodiment 1 is that in Embodiment 1, each triggering device 21 is arranged on the same substrate to form a trigger module. In this embodiment, however, the triggering device 21 is directly fixed to the secondary winding 31 of the motor.

[0053] An embodiment of the position detection device for a cableless linear motor in this invention: The embodiment of the position detection device for a cableless linear motor is the position detection device described in any of the embodiments of the cableless linear motor described above, and will not be specifically described here.

[0054] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. The scope of patent protection of the present invention shall be determined by the claims. Similarly, any equivalent structural changes made based on the description and drawings of the present invention shall also be included within the scope of protection of the present invention.

Claims

1. A cableless linear motor, comprising a primary motor (11), wherein a secondary motor (31) is guidedly mounted on the primary base of the primary motor (11); further comprising a position detection device for detecting the position of the secondary motor (31) on the primary motor (11), the position detection device comprising a detection sensor (41) and a triggering device (21) for triggering the detection sensor (41); characterized in that, Multiple groups of detection sensors (41) are provided. Each group of detection sensors is arranged at intervals on the primary (11) of the motor along the length direction of the linear motor. Each detection sensor (41) in each group is arranged in a straight line along the length direction of the linear motor. Triggering devices (21) are arranged in groups and arranged in a straight line on the secondary (31) of the motor along the length direction of the linear motor. The distribution length of the triggering devices (21) is not less than the group spacing between two adjacent groups of detection sensors (41). When the triggering device (21) at the end of the triggering device arrangement direction is far away from the last detection sensor (41) on the corresponding group of detection sensors, the triggering device (21) at the beginning of the triggering device arrangement direction can trigger the detection sensor (41) in the adjacent group of detection sensors. Detection sensors (41) with the same arrangement position on each group of detection sensors are connected in parallel to each other. When the detection sensor (41) at the corresponding position on any group of detection sensors is triggered, the corresponding transmission cable (43) can output a signal. The position detection device also includes an encoder (44) for processing the signal emitted by the detection sensor (41).

2. The cableless linear motor according to claim 1, characterized in that, Each trigger device (21) is arranged on the same substrate to form a trigger module.

3. The cableless linear motor according to claim 2, characterized in that, The center distance between two adjacent trigger devices (21) is set according to the pole pitch of the corresponding linear motor so as to be equal to the pole pitch of the linear motor.

4. The cableless linear motor according to claim 1, 2, or 3, characterized in that, Each set of detection sensors is arranged on a circuit board (42).

5. The cableless linear motor according to claim 1, 2, or 3, characterized in that, The triggering device (21) is a magnet, and the magnetic field polarities of the ends of two adjacent magnets that are close to each other are opposite; the detection sensor (41) is a switch-type Hall sensor.

6. A position detection device for a cableless linear motor, comprising a detection sensor (41) and a triggering device (21) for triggering the detection sensor (41); characterized in that, Multiple groups of detection sensors (41) are provided. Each group of detection sensors is arranged at intervals on the primary (11) of the motor along the length direction of the linear motor. Each detection sensor (41) in each group is arranged in a straight line along the length direction of the linear motor. Triggering devices (21) are arranged in groups and arranged in a straight line on the secondary (31) of the motor along the length direction of the linear motor. The distribution length of the triggering devices (21) is not less than the group spacing between two adjacent groups of detection sensors (41). When the triggering device (21) at the end of the triggering device arrangement direction is far away from the last detection sensor (41) on the corresponding group of detection sensors, the triggering device (21) at the beginning of the triggering device arrangement direction can trigger the detection sensor (41) in the adjacent group of detection sensors. Detection sensors (41) with the same arrangement position on each group of detection sensors are connected in parallel to each other. When the detection sensor (41) at the corresponding position on any group of detection sensors is triggered, the corresponding transmission cable (43) can output a signal. The position detection device also includes an encoder (44) for processing the signal emitted by the detection sensor (41).

7. The position detection device for a cableless linear motor according to claim 6, characterized in that, Each trigger device (21) is arranged on the same substrate to form a trigger module.

8. The position detection device for a cableless linear motor according to claim 7, characterized in that, The center distance between two adjacent trigger devices (21) is set according to the pole pitch of the corresponding linear motor so as to be equal to the pole pitch of the linear motor.

9. The position detection device for a cableless linear motor according to claim 6, 7, or 8, characterized in that, Each set of detection sensors is arranged on a circuit board (42).

10. The position detection device for a cableless linear motor according to claim 6, 7, or 8, characterized in that, The triggering device (21) is a magnet, and the magnetic field polarities of the ends of two adjacent magnets that are close to each other are opposite; the detection sensor (41) is a switch-type Hall sensor.

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