Integrated intelligent brushless direct current motor and electric push rod integrated system

Abstract

The invention discloses an integrated intelligent brushless direct current motor electric push rod integrated system, belongs to the technical field of electric actuators, and particularly comprises a system for limiting the stroke of a push rod without a mechanical contact, a motor operation control circuit and an integrated brushless direct current motor electric push rod. The motor operation control circuit is used in cooperation with the non-contact limiting module, so that the stroke of the push rod is detected, calibrated and controlled, the problem that a traditional mechanical contact type relay or a limiting switch is prone to being damaged is solved, and stroke error accumulation is eliminated. The multiple sensors in the non-contact limiting module are connected on one PCB, the length of forward and reverse rotation control signals and sensor signal lines can be shortened, the electric push rod structure and application of the electric push rod structure are highly integrated, in addition, a power line, an external control signal communication line and the like are integrated into a multi-split wire harness, wiring can be simplified, and the cost is reduced. And the production and assembly efficiency is improved.

Description

Technical Field

[0001] The invention belongs to the technical field of electric actuators, and in particular relates to an integrated intelligent brushless DC motor electric push rod integrated system. Background Art

[0002] At present, most electric push rods are driven by brushed DC motors without rotor position signals, and the extension or retraction limit position control and stop protection control of the electric push rod's linear motion are realized by turning on and off the mechanical limit switch built into the threaded push rod sleeve. At present, the conventional means is to use traditional mechanical contact relays or DC power supply reversing controllers (patent: ZL202123425113.0) to realize the reversing control of the power supply polarity of the DC motor, thereby controlling the extension or retraction of the electric push rod. At the same time, the electric push rod will use the nut switch arm of the threaded screw to press the button of the limit switch to disconnect its normally closed contact, cut off the power supply of the DC motor, and perform limit stop protection control.

[0003] However, in actual applications, conventional electric push rods will have the disadvantages of short life and high failure probability of commutators and limit switches due to commutation sparks, mechanical wear, forced shutdown current, contact arc damage and fatigue damage of mechanical springs. The mechanical wear of the limit switch may also cause over-extension of the push rod, resulting in overload damage to the motor and switch components. Therefore, a solution that can solve the above problems is needed. Summary of the invention

[0004] The purpose of the present invention is to provide an integrated intelligent brushless DC motor electric push rod integrated system to solve the problems raised in the above background technology.

[0005] To achieve the above-mentioned purpose, a technical solution adopted by the present invention is: a system for limiting the stroke of a push rod without mechanical contacts, comprising a motor, a contactless limit module and a push rod assembly for installing a push rod, the contactless limit module senses that the push rod is in a set position and sends out a running signal, a stop signal or a stroke calibration correction signal, and the motor or the push rod assembly is provided with a controller for receiving the contactless limit module and controlling the operating state of the motor.

[0006] Preferably, the push rod assembly includes a push rod housing, a screw rod and a transmission member threadedly connected to the screw rod, and the push rod is connected to the transmission member and can extend or retract under the action of the screw rod.

[0007] Preferably, the contactless limit module includes an extension stroke reaching target position sensor and a retraction stroke reaching target position sensor, and the push rod assembly is provided with a sensing part for the extension stroke reaching target position sensor and the retraction stroke reaching target position sensor to identify the current position of the push rod.

[0008] Preferably, the contactless limit module further includes at least one push rod extreme extension position stop sensor and at least one push rod extreme retraction position stop sensor, and an induction part two for the push rod extreme extension position stop sensor and the push rod extreme retraction position stop sensor to identify the current position of the push rod is arranged on the push rod assembly.

[0009] Preferably, the contactless limit module further includes at least one position correction sensor for calibrating and correcting the stroke position of the push rod.

[0010] Preferably, a plurality of Hall position sensors are arranged in the motor. The Hall position sensors are distributed in a circumferential array with the rotation axis of the rotor as the center. The Hall position sensors are electrically connected to the controller and are used to transmit the position information and speed information of the rotor in the motor to the controller, and cooperate with the reduction ratio of the transmission gear and the lead of the screw push rod to achieve accurate control of the electric push rod and prevent the push rod from overextending or overretracting.

[0011] Preferably, the contactless limit module includes one or more of a magnetic sensor, an optical sensor, or an acoustic sensor.

[0012] A motor operation control circuit is applied to a system for limiting the stroke of a push rod without mechanical contacts described above. The circuit is placed on a PCB board to implement the functions of the above controller. The circuit includes a microcontroller, a driving circuit for PWM control signals, and a three-phase full-bridge inverter circuit. The contactless limit module is electrically connected to the microcontroller and issues three-phase PWM control instructions through the PWM control signal output port of the microcontroller. After the driving circuit for the three-phase PWM control signals converts and conditions the three-phase PWM control instructions, it controls the three-phase full-bridge inverter circuit to output three-phase voltages.

[0013] Preferably, a load current sampling and overcurrent protection circuit is further arranged on the PCB board. One end interface of the load current sampling and overcurrent protection circuit is connected to the source common terminal of the N-MOS transistors Q 2 、Q 4 、Q 6 in the three-phase full-bridge inverter circuit, and the other end interface of the load current sampling and overcurrent protection circuit is connected to the microcontroller.

[0014] Preferably, the load current sampling and overcurrent protection circuit includes an operational amplifier AMP and resistors R 10 、R 11 、R 12 、R 13 、R 14 , The operational amplifier AMP and resistors R 11 、R 12 、R 13 、R14 forms a non-inverting summer, and the non-inverting input terminal of the operational amplifier AMP is connected to the source common terminal of the N-MOS transistors Q 2 , Q 4 , Q 6 in the three-phase inverter circuit. The inverting input terminal of the operational amplifier AMP is grounded through a resistor R 14 . The output terminal of the operational amplifier AMP is connected to the microcontroller. Among them, the sampling resistor R 10 is connected into the three-phase inverter circuit and is placed between the non-inverting input terminal of the operational amplifier AMP and the ground terminal to play a role in current sampling.

[0015] Preferably, a temperature detection circuit is further provided on the PCB board. The temperature detection circuit includes voltage-dividing resistors R 1 , R 2 and a negative temperature coefficient thermistor NTC. The temperature detection circuit is electrically connected to the microcontroller.

[0016] Preferably, the displacement amount of the push rod stroke realized by each change of the Hall state of the Hall position sensor provided in the motor is less than 10 micrometers.

[0017] An integrated brushless DC motor electric push rod, the push rod assembly further includes a fixed base and a push rod outer end cover. At least two connection and fixing parts are provided on the push rod assembly for fixing the push rod outer end cover, the push rod housing and the fixed base together;

[0018] The motor is fixed on the fixed base. The motor includes a motor housing, a motor upper end cover, a motor bottom cover, and a stator and a rotor placed inside the motor housing. At least two connection and fixing parts are provided on the motor for fixing the motor housing, the motor upper end cover and the motor bottom cover together.

[0019] Preferably, the connection and fixing parts are provided on the outer walls of the push rod outer end cover, the push rod housing and the fixed base in the push rod assembly or on the outer walls of the motor housing, the motor upper end cover and the motor bottom cover in the motor. The cross-section of the connection and fixing part is in the shape of one or a combination of an ear-shaped, square, circular, semi-circular and triangular shape, and each connection and fixing part is fixed by a long bolt.

[0020] Preferably, a power supply and signal path access port is provided on the PCB board, and a one-to-many integrated wire harness is connected at the power supply and signal path access port. The integrated wire harness includes a power line, an external control signal communication line and other functional lines.

[0021] Advantages of the present invention: In the hardware structure of the present invention, a non-contact sensor is adopted to replace the built-in mechanical limit switch of the linear motion push rod, avoiding the problem of mechanical contact aging; by setting the sensor for reaching the target position in the extending stroke and the sensor for reaching the target position in the retracting stroke, the positioning of the telescopic stroke operation of the electric push rod is realized; at the same time, by setting the stop sensor for the limit extended position of the push rod and the stop sensor for the limit retracted position of the push rod, the possibility of over-extension or over-retraction of the electric push rod is avoided. In addition, a plurality of Hall position sensors are arranged in the motor, which can transmit the position information and speed information of the rotor in the motor to the controller. The controller determines the current stroke of the push rod by combining the signals transmitted by the Hall position sensors, the reduction ratio of the transmission gear and the lead of the screw rod, and by comparing with the set stroke, further avoids the possibility of over-extension or over-retraction of the electric push rod, realizes the double over-telescopic limit stop protection of the push rod stroke, improves the service life and operation reliability of the electric push rod. Moreover, by setting the position correction sensor, the stroke error accumulation caused by factors such as motor speed error, transmission error of the reduction gear set and screw pitch error in each extension or retraction process can be eliminated, ensuring the accuracy of the push rod stroke position. At the same time, it can also function as a reference point for the push rod stroke, ensuring that the push rod accurately reaches the target position during operation.

[0022] Among them, an electronic controller without commutation sparks is used to replace the mechanical commutator of the DC motor, avoiding commutation electric sparks and brush noise. At the same time, the motor operation control circuit for controlling the integrated intelligent brushless DC motor electric push rod in the present invention can perform real-time detection of the working current of the electric push rod, the power supply voltage, and the temperature of the PCB board and the MOS transistors thereon, realizing the functions of overcurrent, undervoltage, and overheat protection and alarm for the PCB board and the MOS transistors, thereby avoiding the damage of the electric push rod due to excessive overcurrent or too high temperature of the MOS transistors, etc. during operation, and also avoiding the burnout of the switching tube due to too low DC power supply voltage causing the switching tube to work in the amplification state, improving the working reliability of the electric push rod. At the same time, the circuit can realize the three-closed-loop control of the electric thrust, running speed and position of the screw rod by real-time monitoring of the rotor position and its speed in the motor through a plurality of Hall position sensors arranged in the motor under the condition of matching the gear reduction ratio and the lead of the screw rod, greatly improving the performance of the electric push rod, especially its response speed, positioning accuracy and self-locking force;

[0023] For example, assume that the brushless DC motor of the electric push rod has 9 slots and 10 poles, the number of pole pairs p = 5, and the gear reduction ratio k of the transmission gear set 1 *k 2 *k 3 = 20, and the lead h of the screw rod is 3.175 mm. The displacement of a Hall state electric push rod can be accurately up to about 5.3 microns, far exceeding the accuracy of the push rod controlled by a conventional brushed DC motor.

[0024] Moreover, in a conventional group of DC brushed electric pushrods, the controller is usually external and uniformly arranged in a control cabinet. By integrating the controller onto the electric pushrod or the motor, the present invention greatly reduces the volume of the control cabinet. The more electric pushrods there are in the electric pushrod group, the more cost can be saved. Meanwhile, during the overall wiring connection process of the present invention, power supply wires and signal wires of position sensors can be significantly saved, and the number of I / O terminals of the PLC or the upper computer can be eliminated. The more the number of applied electric pushrod groups, the more remarkable the cost-saving effect. In addition, the electric pushrods of the present invention adopt a simple one-to-many integrated wiring harness for external lead connection and a firm and reliable special sensor connector, which greatly simplifies the assembly wiring method and the maintenance process. Different leads can be distinguished by colors, etc., avoiding accidental failures caused by incorrect wiring of signal leads;

[0025] In addition, in the setting of a conventional brushed DC motor or pushrod assembly, the functional part for realizing the connection and fixing part is usually arranged inside the pushrod housing or the motor housing. For example, in a motor, since the part generating power inside the motor is generally cylindrical, the motor housing needs to fit the shape of the power-generating part of the motor. The addition of the functional part for realizing the connection and fixing part will undoubtedly increase the overall volume of the motor. The present invention adopts an external fixing method with a cross-section in the shape of an ear, a square or other shapes on the outer peripheral wall of the motor housing or the pushrod housing. Both the motor and the pushrod assembly can complete their overall connection and fixing through the connection and fixing part. Compared with the way of connecting each part of the conventional motor or pushrod assembly pairwise, the one-piece fixing method in the present invention reduces the volume of the motor and the pushrod assembly. At the same time, the overall one-time fixing method can further enhance the stability and firmness of the installation of the motor or the pushrod assembly compared with the way of connecting each component pairwise in the conventional manner. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 is the circuit diagram for controlling the operation of the motor in the present invention;

[0027] Figure 2 is the schematic diagram of the structure and connection relationship of the motor and the pushrod assembly in the present invention;

[0028] Figure 3 is the exploded view of the structure and connection relationship of the motor and the pushrod assembly in the present invention;

[0029] Figure 4 is the schematic diagram of the positional relationship of each component when the pushrod extends in the non-contact limit module, the motor and the pushrod assembly in the present invention;

[0030] Figure 5 is the schematic diagram of the positional relationship of each component when the pushrod retracts in the non-contact limit module, the motor and the pushrod assembly in the present invention;

[0031] Figure 6 It is a schematic diagram of the branch line of the integrated wire harness;

[0032] In the figure: 1. Motor; 101. Push rod assembly; 2. Lead screw; 3. Push rod; 4. Gear structure; 5. Extension stroke reaching the target position sensor; 6. Retraction stroke reaching the target position sensor; 7. Position correction sensor; 8. Push rod extreme extension position stop sensor; 9. Push rod extreme retraction position stop sensor; 10. Magnetic nut; 11. Integrated wire harness; 12. Fixed base; 13. Upper end cover of the motor; 14. Motor housing; 15. Bottom cover of the motor; 16. Long bolt; 17. Push rod housing; 18. Outer end cover of the push rod; 19. Power cord; 20. External control signal communication line; 21. Other functional lines. Specific embodiments

[0033] The following elaborates on the preferred embodiments of the present invention in conjunction with the accompanying drawings, so that the advantages and features of the present invention can be more easily understood by those skilled in the art, thereby making a clearer and more definite definition of the protection scope of the present invention.

[0034] Embodiment:

[0035] An integrated intelligent brushless DC motor electric push rod system includes a system for limiting the push rod stroke without mechanical contacts, a motor operation control circuit applied to the method of limiting the push rod stroke without mechanical contacts, and an integrated brushless DC motor electric push rod including the motor operation control circuit.

[0036] Among them, referring to Figure 2 , Figure 3 , the integrated brushless DC motor electric push rod includes a motor 1, a push rod assembly 101 and a non-contact limit module. A controller for receiving the non-contact limit module and controlling the operation state of the motor 1 is provided on the motor 1 or the push rod assembly 101. The motor 1 and the push rod assembly 101 are driven by a gear structure 4. The push rod assembly 101 includes an outer end cover 18 of the push rod, a push rod housing 17, a lead screw 2, a transmission member threadedly connected to the lead screw 2, and a fixed base 12. The push rod 3 is connected to the transmission member and realizes the extension or retraction action under the action of the lead screw 2. The motor 1 includes an upper end cover 13 of the motor, a motor housing 14, a bottom cover 15 of the motor, and a stator and a rotor including three-phase windings placed inside the motor housing 14. Among them, at least two connection and fixing parts are provided on the outer end cover 18 of the push rod, the push rod housing 17 and the fixed base 12 to fix each part together. Among them, at least two connection and fixing parts are also provided on the upper end cover 13 of the motor, the motor housing 14 and the bottom cover 15 of the motor to fix each part together. Referring to Figure 2 , Figure 3, in this embodiment, the connection and fixing part is an outer ear structure (the shape of the ear refers to the shape of the ear-bearing), and each part is fixed by connecting each group of connection and fixing parts with a long bolt 16. In the setting of the conventional motor 1 or the push rod assembly 101, the functional part for realizing the connection and fixing part is usually arranged inside the push rod housing 17 or the motor housing 14. For example, in some motors 1, since the part generating power inside the motor 1 is integrally cylindrical, the motor housing 14 needs to fit the shape of the power generating part of the motor 1, and the addition of the functional part for realizing the connection and fixing part will undoubtedly increase the overall volume of the motor 1. Through the structural design of the outer ear, the present invention can reduce the overall volume of the motor 1 or the push rod assembly 101, and the fixing is quite firm, making the connection between the motor 1 and the push rod assembly 101 more stable. At the same time, in this embodiment, the motor 1 is also fixed on the fixed base 12 to ensure the overall integration of the electric push rod 3. It can fix the motor 1 on the fixed base 12 through the long bolt 16, or fix the motor 1 and the fixed base 12 together in other ways. It should be noted that the connection and fixing part in the present invention can be of other shapes, such as square, triangular, etc., and it is only necessary to ensure that it is small in volume, beautiful, safe, low in cost and firm in the overall connection part with the motor 1 or the push rod assembly 101 when designed.

[0037] Refer to Figure 4 , Figure 5, the contactless limit module includes a forward stroke reaching target position sensor 5 and a retraction stroke reaching target position sensor 6 arranged on the external load device. The forward stroke reaching target position sensor 5 and the retraction stroke reaching target position sensor 6 can determine whether the push rod 3 reaches the set position by identifying the position of the end of the push rod 3. Among them, the forward stroke reaching target position sensor 5 and the retraction stroke reaching target position sensor 6 are connected to the controller through a set of integrated wiring harnesses, which also reflects the overall concept of integrating as much as possible in this solution; the contactless limit module also includes a push rod extreme extension position stop sensor 8, a position correction sensor 7, and a push rod extreme retraction position stop sensor 9 arranged in sequence along the length direction of the push rod housing 17 inside the push rod housing 17. The push rod extreme extension position stop sensor 8, the position correction sensor 7, and the push rod extreme retraction position stop sensor 9 are connected to the controller through signal lead-out wires; the above sensors can use one or more of magnetic sensors, photoelectric sensors, or acoustic sensors. In this embodiment, a Hall sensor in the magnetic sensors is used. Among them, an induction part two for the push rod extreme extension position stop sensor 8, the position correction sensor 7, and the push rod extreme retraction position stop sensor 9 to identify is arranged on the transmission part. In this example, the transmission part is the induction part two, and the transmission part is a nut embedded with magnetic material. When the magnetic nut 10 passes by, the push rod extreme extension position stop sensor 8 and the push rod extreme retraction position stop sensor 9 can determine whether the push rod 3 exceeds the set stroke by identifying the position of the magnetic nut 10 and stop the push rod 3 at the extreme position of over-extension or over-retraction beyond the set stroke by transmitting the position signal to the controller. At the same time, the position correction sensor 7 can avoid the accumulation of stroke errors caused by factors such as the rotational speed error of the motor 1, the transmission error of the reduction gear set, and the lead error of the screw thread lead screw 2 during each extension or retraction process of the electric push rod 3, ensuring the accuracy of the stroke position of the push rod 3. At the same time, it can also be used as a reference point for the push rod stroke to ensure that the push rod accurately reaches the target position during operation;

[0038] In addition, three Hall position sensors are arranged in the motor 1. The three Hall position sensors are circumferentially arrayed with the rotation axis of the rotor as the center and are distributed at intervals of 120 degrees in sequence. The Hall position sensors are electrically connected to the controller and are used to transmit the position information and speed information of the rotor in the motor 1 to the controller. The controller determines the current stroke of the push rod 3 by combining the signals transmitted by the Hall position sensors with the gear reduction ratio and the lead of the screw thread lead screw, and determines whether the stroke of the push rod 3 exceeds the set stroke by comparing it with the set stroke, further avoiding the possibility of over-extension or over-retraction of the electric push rod 3 and realizing the double limit position stop protection for the stroke of the push rod 3.

[0039] Among them, the controller is fixed inside the motor housing 14 (the controller realizes its functions through an integrated PCB). Such a setting can effectively reduce the overall volume by integrating the controller into the motor 1, making the electric push rod 3 more integrated. Among them, the motor 1 operation control circuit is arranged on the PCB board. This circuit includes a microcontroller MCU, a driving circuit for PWM control signals, and a three-phase full-bridge inverter circuit. The non-contact limit module is electrically connected to the microcontroller MCU and issues three-phase PWM control instructions through the PWM port of the microcontroller MCU. After the driving circuit for PWM control signals converts and conditions the control instructions, it controls the three-phase full-bridge inverter circuit to output three-phase voltages.

[0040] Specifically, refer to Figure 1 , in this embodiment, one end of the microcontroller MCU is connected to the +5V power supply, and the other end is grounded. The microcontroller MCU, the PWM signal driving circuit, and the three-phase full-bridge inverter circuit are electrically connected in sequence. Among them, the three-phase full-bridge inverter circuit includes three P-MOS transistors Q 1 , Q 3 , Q 5 and three N-MOS transistors Q 2 , Q 4 , Q 6 . The gates of the six MOS transistors are all connected to the driving circuit for PWM control signals. The sources of the three P-MOS transistors Q 1 , Q 3 , Q 5 are commonly connected to the +24V power supply. The sources of the three N-MOS transistors Q 2 , Q 4 , Q 6 are commonly grounded. The drain of Q 1 and the drain of Q 4 are connected and commonly connected to one winding of the motor 1. The drain of Q 3 and the drain of Q 6 are connected and commonly connected to one winding of the motor 1. The drain of Q 5 and the drain of Q 2 are connected and commonly connected to one winding of the motor 1. In addition, a diode for freewheeling is connected in parallel between the source and drain of each MOS transistor. The positive pole of the parallel diode on the PMOS transistor is connected to the drain of the MOS transistor, and the positive pole of the parallel diode on the NMOS transistor is connected to the source of the MOS transistor.

[0041] Among them, the extension stroke reaching the target position sensor 5, the retraction stroke reaching the target position sensor 6, the push rod extreme extension position stop sensor 8, the position correction sensor 7, and the push rod extreme retraction position stop sensor 9 are all connected to the input port of the microcontroller MCU through signal lines. Three Hall position sensors on the motor 1, which are used to transmit the position information and speed information of the inner rotor of the motor 1 to the controller, are fixed on the PCB board. By transmitting the position information and speed information of the inner rotor of the motor 1 to the controller, the control of the operating stroke of the push rod 3 is realized. In the above process, the microcontroller MCU will control the 6-channel PWM output port to issue corresponding control instructions: DU_H, DU_L, DV_H, DV_L, DW_H, DW_L according to the received instructions and the motor 1 rotor position information detected by the Hall sensor. After the control instructions are converted and conditioned by the three-phase control signal drive circuit U3, 6-channel control signals U_H, U_L, V_H, V_L, W_H, W_L with the function of preventing the same bridge arm from directly connecting and interlocking protection are output, respectively controlling the switching devices Q 1 ~Q 6 According to a certain conduction or cutoff logic, control the conduction or cutoff of the 6 power switch tubes Q 1 ~Q 6 so as to convert the DC power supply voltage of 0~+24V into three-phase alternating voltages U, V, and W, which are respectively applied to the three-phase windings of the motor 1, realizing the start-stop or rotation direction control of the brushless DC motor 1, and controlling the current and speed during the operation of the motor by adjusting the PWM output signal. At the same time, the calculation of the stroke when the push rod reaches the target position is also realized, and then the entire operating state of the electric push rod 3 is controlled until the position sensor of the external load device sends a signal to change the operating state, so as to realize the stop of the push rod 3 when the stroke reaches the target position;

[0042] In this embodiment, the rotor Hall position sensor transmits the detected position signal of the brushless DC motor 1 to the microcontroller MCU. The microcontroller MCU will control the telescopic stroke of the threaded push rod 3 according to the position signal, the gear reduction ratio of the transmission mechanism of the electric push rod 3, and the lead of the threaded screw rod, and accurately control the extreme positions of the threaded push rod 3, so as to realize the high-precision closed-loop control of the displacement. For example, assume that the motor 1 drives the threaded push rod 3 through three-stage reduction gear transmission, and its gear reduction ratio is k = k 1 k 2 k 3 (ki represents the i-level reduction ratio, i = 1, 2, 3...), the number of pole pairs of the brushless DC motor 1 is p pairs, and the lead of the threaded push rod 3 is h. Then the displacement d that the rotor position of the brushless DC motor 1 corresponding to each Hall state can control the electric push rod 3 to advance or retreat is:

[0043] d = (1 / 6p) * (h / k 1 k 2 k 3 )

[0044] Through the above formula, we assume that the brushless DC motor 1 of the electric push rod 3 has 9 slots and 10 poles, the number of pole pairs p = 5, and the gear reduction ratio k of the transmission gear set 1 *k 2 *k 3 = 20, the lead h of the threaded screw rod 2 = 3.175 mm. Therefore, the displacement of the electric push rod 3 that can be controlled by each change in the Hall state is:

[0045] d = (1 / 6 * 5) * (3.175 / 20) ≈ 5.29 (micrometers)

[0046] During the control process of the stroke of the push rod 3, the rotor position and speed of the motor 1 can be measured according to the Hall state reflecting the rotor position information, and the stroke and required speed of the push rod 3 reaching the target position can be calculated. Furthermore, by controlling the control signal of the three-phase PWM and the displacement of the threaded screw rod 2, the high-precision speed and position closed-loop control of the push rod 3 can be realized. From the above calculations, it can also be seen that the present invention can achieve high-precision control of the speed and stroke position of the push rod 3, enabling the present invention to be applied to a more high-precision usage environment;

[0047] Among them, a load current sampling and overcurrent protection circuit is also provided on the PCB board. Specifically, the load current sampling and overcurrent protection circuit includes an operational amplifier AMP and resistors R 10 、R 11 、R 12 、R 13 、R 14 , the operational amplifier AMP and the resistors R 11 、R 12 、R 13 、R 14 constitute a non-inverting adder. Among them, one end of the parallel connection of R 12 、R 13 is connected to the non-inverting input terminal of the operational amplifier AMP, the other end of R 12 is connected to the reference voltage signal V_ref, the other end of R 13 is connected to the common terminal line of the three-phase inverter circuit, the inverting input terminal of the operational amplifier AMP is grounded through the resistor R 14 , the output terminal of the operational amplifier AMP is connected to the ADC input port of the microcontroller MCU. At the same time, the output signal of the AMP is connected to the inverting input terminal through the feedback resistor R 11 . In addition, one end of the resistor R 13 connected to the three-phase inverter circuit and the resistor R 14A capacitor for filtering is connected between one of the grounded ends, and the resistor R 10 has one end grounded and the other end connected to the source common terminal of the N-MOS transistors Q 2 , Q 4 , Q 6 in the three-phase inverter circuit; in the above circuit, when the current of any phase of the motor 1 changes, the current I_shunt and the voltage V R10 across the sampling resistor R10 will change synchronously, and the voltage signal V AMP_O at the output end of the operational amplifier AMP will also change accordingly. The microcontroller MCU controls the duty cycle of the PWM signal according to the comparison result between the detected current signal of the motor 1 and the reference threshold, thereby controlling the conduction time of the switching device and the voltage of the motor 1, and realizing the control of the operating state of the electric push rod 3. At the same time, the position and speed of the rotor can be detected according to the three Hall position sensors on the PCB board, and the speed and position closed-loop control of the motor 1 or the lead screw of the electric push rod 3 can be realized. In addition, the current sampling link also has an overcurrent protection control function. For example, when the load current I_shunt increases and exceeds the maximum value of the allowable current range, in the case of having a PLC or a host computer, the microcontroller MCU sends an overcurrent alarm device to the PLC or the host computer through the serial communication RS485 or the CAN bus. At the same time, it can also send a PWM control signal to turn off all the MOSFET power switch tubes, so that the electric push rod 3 stops running, thereby avoiding the power switch tubes on the PCB in the BLDC motor 1 of the electric push rod 3 from being burned out due to overcurrent. The current detection and the PWM control of the motor 1 voltage can also realize the closed-loop control of the motor 1 current, that is, the closed-loop control of the motor 1 torque or the force of the push rod 3.

[0048] In addition, a temperature detection circuit is also provided on the PCB board to monitor the temperature of the PCB board or the MOS transistor. The temperature detection circuit includes voltage-dividing resistors R 1 , R 2 and a negative temperature coefficient thermistor NTC. Specifically, one end of the thermistor NTC is connected to the +5V power supply through a resistor R 2 , and the other end is grounded. At the same time, a voltage-dividing resistor R 2 is connected between the thermistor NTC and the resistor R 1 . The thermistor NTC is connected to the ADC input port of the microcontroller MCU through R 1 . At the same time, a capacitor C 1 is connected to one end of the voltage-dividing resistor R 2 connected to the ADC input port of the microcontroller MCU, and the other end of the capacitor C 2 is grounded. The capacitor C 2It plays a filtering role. Since the integrated controller of the electric push rod 3 in this invention application is encapsulated inside the motor 1, the heat dissipation of the power switching device will be affected to a certain extent. Therefore, real-time monitoring of the working temperature of the MOS tube can prevent the MOS tube from being damaged due to excessive die temperature, thereby extending the service life of the MOS tube and improving the reliability and service life of the electric push rod 3.

[0049] Among them, an undervoltage detection circuit is also provided on the PCB board. Specifically, the undervoltage detection circuit includes resistors R 6 and R 7 in series. The other end of R 6 is connected to the +24V voltage, the other end of R 7 is grounded. A resistor R 6 connected to the ADC input port of the microcontroller MCU is connected between R 7 and R 4 . A capacitor C 4 is connected to the end where the resistor R 3 is connected to the ADC input port of the microcontroller MCU. The other end of the capacitor C 3 is grounded. This capacitor C 3 plays a filtering role. In this circuit, if the circuit experiences undervoltage, the microcontroller MCU can cut off the power in time to protect the electrical appliance from the harm of too low voltage.

[0050] In addition, referring to Figure 6 , a power supply and signal path access port is provided on the PCB board. At the power supply and signal path access port, a one-to-many integrated wire harness 11 is connected. The integrated wire harness 11 includes a power line 19, an external control signal communication line 20, and other functional lines 21 set as needed, etc., to form a one-to-five integrated wire harness 11. The PCB board can achieve communication connection with a PLC or a host computer, etc. by accessing the integrated wire harness including an RS485 bus or a CAN bus, etc. at the power supply and signal path access port.

[0051] The above are only the embodiments of the present invention, and do not limit the patent scope of the present invention accordingly. Any equivalent structural transformation made by using the content of the specification and drawings of the present invention, or directly or indirectly applied in other related technical fields, shall be similarly included in the patent protection scope of the present invention.

Claims

1. A system for limiting the stroke of a push rod without mechanical contacts, characterized in that: It includes a motor (1), a non-contact limit module, and a push rod assembly (101) for the device push rod (3). When the non-contact limit module senses that the push rod (3) is at the set position, it emits an operation signal, a stop signal, or a stroke calibration correction signal. A controller for receiving the non-contact limit module and controlling the operating state of the motor (1) is provided on the motor (1) or the push rod assembly (101).

2. A system for limiting the stroke of a push rod without mechanical contacts according to claim 1, characterized in that: The push rod assembly (101) includes a push rod housing (17), a lead screw (2), and a transmission member threadedly connected to the lead screw (2). The push rod (3) is connected to the transmission member and realizes the extension or retraction action under the action of the lead screw (2).

3. A system for limiting the stroke of a push rod without mechanical contacts according to claim 2, characterized in that: The non-contact limit module includes a target position sensor (5) for the extension stroke and a target position sensor (6) for the retraction stroke. An induction part one for the target position sensor (5) for the extension stroke and the target position sensor (6) for the retraction stroke to identify the current position of the push rod (3) is provided on the push rod assembly (101).

4. A system for limiting the stroke of a push rod without mechanical contacts according to claim 3, characterized in that: The non-contact limit module further includes at least one push rod extreme extension position stop sensor (8) and at least one push rod extreme retraction position stop sensor (9). An induction part two for the push rod extreme extension position stop sensor (8) and the push rod extreme retraction position stop sensor (9) to identify the current position of the push rod (3) is provided on the push rod assembly (101).

5. A system for limiting the stroke of a push rod without mechanical contacts according to claim 4, characterized in that: The non-contact limit module further includes at least one position correction sensor (7) for calibrating and correcting the stroke position of the push rod (3).

6. A system for limiting the stroke of a push rod without mechanical contacts according to claim 3, characterized in that: A plurality of Hall position sensors are provided in the motor (1). The Hall position sensors are distributed in a circumferential array with the rotating shaft of the rotor as the center. The Hall position sensors are electrically connected to the controller and are used to transmit the position information and speed information of the rotor in the motor (1) to the controller, and cooperate with the reduction ratio of the transmission gear and the lead of the threaded push rod to achieve accurate control of the electric push rod (3) and prevent the push rod (3) from overextending or overretracting.

7. A system for limiting the stroke of a push rod without mechanical contacts according to claim 1, characterized in that: The non-contact limit module includes one or more of a magnetic sensor, an optical sensor, or an acoustic sensor.

8. A motor operation control circuit applied to the method for limiting the stroke of a push rod without mechanical contacts according to any one of claims 1-7, characterized in that: The circuit is placed on a PCB board to implement the functions of the above-mentioned controller. The circuit includes a microcontroller, a driving circuit for PWM control signals, and a three-phase full-bridge inverter circuit. The contactless limit module is electrically connected to the microcontroller and issues three-phase PWM control instructions through the PWM control signal output port of the microcontroller. After converting and conditioning the three-phase PWM control instructions, the driving circuit of the three-phase PWM control signals controls the three-phase full-bridge inverter circuit to output three-phase voltages.

9. A motor operation control circuit according to claim 8, characterized in that: A load current sampling and overcurrent protection circuit is also provided on the PCB board. One end interface of the load current sampling and overcurrent protection circuit is connected to the source common terminal of N-MOS transistors Q 2 , Q 4 , Q 6 in the three-phase full-bridge inverter circuit, and the other end interface of the load current sampling and overcurrent protection circuit is connected to the microcontroller.

10. A motor operation control circuit according to claim 9, characterized in that: The load current sampling and overcurrent protection circuit includes an operational amplifier AMP and resistors R 10 , R 11 , R 12 , R 13 , R 14 , the operational amplifier AMP and resistors R 11 , R 12 , R 13 , R 14 form a non-inverting adder. The non-inverting input terminal of the operational amplifier AMP is connected to the common source terminal of N-MOS transistors Q 2 , Q 4 , Q 6 in the three-phase inverter circuit. The inverting input terminal of the operational amplifier AMP is grounded through resistor R 14 . The output terminal of the operational amplifier AMP is connected to the microcontroller. Among them, the sampling resistor R 10 is connected into the three-phase inverter circuit and is placed between the non-inverting input terminal of the operational amplifier AMP and the ground terminal to play a role in current sampling.

11. A motor operation control circuit according to claim 10, characterized in that: A temperature detection circuit is also provided on the PCB board, and the temperature detection circuit includes voltage-dividing resistors R 1 , R 2 and a negative temperature coefficient thermistor NTC, and the temperature detection circuit is electrically connected to the microcontroller.

12. A motor operation control circuit according to claim 8, characterized in that: The displacement of the push rod (3) stroke realized by each change of the Hall state of the Hall position sensor provided in the motor (1) is less than 10 micrometers.

13. An integrated brushless DC motor electric push rod, comprising a motor operation control circuit according to any one of claims 8-12, characterized in that: The push rod assembly (101) further includes a fixed base (12) and a push rod outer end cover (18). At least two connection and fixing parts are provided on the push rod assembly (101) for fixing the push rod outer end cover (18), the push rod outer shell (17) and the fixed base (12) together; The motor (1) is fixed on the fixed base (12). The motor (1) includes a motor outer shell (14), a motor upper end cover (13), a motor bottom cover (15), and a stator and a rotor placed inside the motor outer shell (14). At least two connection and fixing parts are provided on the motor (1) for fixing the motor outer shell (14), the motor upper end cover (13) and the motor bottom cover (15) together.

14. An integrated brushless DC motor electric push rod according to claim 13, characterized in that: The connection and fixing parts are arranged on the outer walls of the push rod outer end cover (18), the push rod outer shell (17) and the fixed base (12) in the push rod assembly (101) or on the outer walls of the motor outer shell (14), the motor upper end cover (13) and the motor bottom cover (15) in the motor (1). The cross-section of the connection and fixing part is in the form of one or a combination of more than one of an ear-shaped, square, circular, semi-circular and triangular shape. Each connection and fixing part is fixed by a long bolt (16).

15. An integrated brushless DC motor electric push rod according to claim 14, characterized in that: A power supply and signal path access port is provided on the PCB board, and a one-to-many integrated wire harness (11) is connected at the power supply and signal path access port. The integrated wire harness (11) includes a power line (19), an external control signal communication line (20) and other functional lines (21).

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