CN115899353A - Actuator for a valve - Google Patents

Abstract

The present disclosure relates generally to actuators for valves. The actuator of the present disclosure includes a stepper motor. The output shaft of the stepper motor is coupled to the drive arm of the valve. The stepper motor moves the actuator arm and a flow control member coupled to the actuator arm. The actuator includes a sensorless stall detection unit to detect stall of the stepper motor based on an operating voltage of the stepper motor.

Description

Actuator for a valve

Background

The present disclosure relates generally to actuators for valves.

Actuators are used to control a variety of valves in a variety of systems. For example, actuators are used in HVAC systems to control valves such as air volume dampers, fluid valves, and other components. The actuator may be coupled to an air volume damper in an HVAC system and may be used to drive the air volume damper between an open position and a closed position. The actuator typically includes a motor and a drive (e.g., hub, drive train) driven by the motor and coupled to the HVAC component.

The configuration of the actuator is determined based on the type of valve to be controlled. One of the conventional actuators for controlling air volume adjusting valves includes a brushless direct current (BLDC) motor coupled to a drive arm of the air volume adjusting valve, which in turn is coupled to a damper of the flow control member-valve. A damper is positioned in the conduit. The conduit may be a pipe, a tube, or the like. The BLDC motor rotates the drive arm of the valve to move the damper to open, close, or partially open the air regulating valve to control the flow of fluid through the conduit. However, the torque capacity of conventional actuators is limited. In addition, a dedicated position sensor is required to determine the locked rotor of the BLDC motor. The drive arm of the flow control device is coupled to the output shaft of the BLDC motor via a number of meshing gear trains, which affects the position control accuracy. Such actuators cannot be used in applications where high positional accuracy is required.

Accordingly, there is a need for an actuator that ameliorates the above-described disadvantages of conventional actuators.

Disclosure of Invention

One embodiment of the present disclosure is an actuator valve including a stepper motor. In an embodiment, an output shaft of the stepper motor is coupled to a drive arm of the valve via a worm and worm gear mesh to move a flow control member of the valve. In some embodiments, the actuator comprises a sensorless stall detection unit. In some embodiments, the unit includes a controller in communication with the stepper motor and adapted to detect stall of the stepper motor based on an operating voltage of the stepper motor. In some embodiments, the actuator has a 90 degree stroke and a torque capacity of 8N-m, with a full stroke travel time of 2 seconds.

The present disclosure further contemplates a method of detecting a stall of a stepper motor. The method comprises the following steps: monitoring the working voltage of the stepping motor; comparing the operating voltage value to a threshold voltage value; stopping the stepper motor if the operating voltage value exceeds the threshold voltage value.

Drawings

Various objects, aspects, features and advantages of the present disclosure will become more apparent and better understood by reference to the detailed description when taken in conjunction with the accompanying drawings in which like reference characters identify corresponding elements throughout. In the drawings, like reference numbers generally indicate identical, functionally similar, and/or structurally similar elements.

Fig. 1 is an isometric view of an actuator according to some embodiments.

Fig. 2 is an isometric view of an actuator according to some embodiments, illustrating an actuator body and a motor.

Fig. 3 is another isometric view of the actuator of fig. 2.

FIG. 4 illustrates a block diagram of a controller associated with the actuator of FIG. 1.

Fig. 5 presents a flowchart depicting method steps performed by the controller for detecting stall detection of the motor of the actuator of fig. 1-3.

FIG. 6 shows a block diagram depicting an electronic circuit for an actuator according to some embodiments.

Detailed Description

SUMMARY

Referring generally to the drawings, an actuator for a valve is shown, according to some embodiments.

The valves described herein may be used to regulate fluid flow from multiple fluid supplies and/or to multiple fluid returns. In some embodiments, the valve is an air volume damper. In some other embodiments, the valve is a three-way valve having a valve body and a valve spool. In another embodiment, the valve is a six-way valve having a valve body and a valve spool. The valve body can include a valve chamber and a plurality of ports (e.g., a first port, a second port, a third port) in fluid communication with the valve chamber. The valve may be controlled (e.g., by an actuator and/or controller) by rotating the spool within the valve chamber.

The actuator may be a damper actuator, a valve actuator, a fan actuator, a pump actuator, or any other type of actuator. In some embodiments, the actuator is used to operate a valve in an HVAC system.

The actuator of the present disclosure includes a stepper motor for operating the flow control member of the valve. The flow control member controls the flow of fluid through the valve body. For example, the damper is a flow control member of the air volume adjusting valve. The hollow and pivoting ball are the flow control components of the ball valve. The flow control member is also referred to as a spool.

The output shaft of the stepper motor is coupled to the drive arm of the valve. The actuator arm is coupled to the flow control member of the valve such that movement of the actuator arm causes movement of the flow control member within the valve body. The valve may be opened, closed or partially opened by moving the flow control member.

The output shaft of the stepper motor may be coupled to the drive arm in various ways. In some embodiments, the output shaft of the stepper motor is coupled to the drive arm using a single-meshing worm gear. The worm gear facilitates the transmission of power and torque between non-intersecting shafts. In some embodiments, the worm gear is mounted on the output shaft of the stepper motor and the worm gear is mounted on the drive arm of the valve, or vice versa. The worm gear meshes with the worm gear to facilitate the transfer of power and torque between the stepper motor and the drive arm. The worm gear improves the torque capacity of the valve.

In some embodiments, the actuator comprises an ultracapacitor. The ultracapacitor stores energy that is used by the actuator during a power failure. The charging time of the capacitor is shorter than that used in conventional actuators. Due to the use of the super capacitor, the flow control member can be returned to the safe position in a short time during a power failure.

In some embodiments, the actuator comprises an automatic stall detection unit. The unit does not require a position sensor, which is typically used for stall detection of BLDC motors. The unit includes a controller that monitors the voltage of the stepper motor to determine a stall event. The controller is set to a voltage threshold. If the stepper motor is operating at a voltage that exceeds the threshold voltage value, the controller generates a disable signal to force the stepper motor to stop. In addition, the controller determines an end stop value for the motor output shaft position and stores the end stop value in memory for future use. As described above, the stall detection unit does not require a position sensor to determine the stall of the stepper motor.

In some embodiments, the actuator includes an adjustable mechanical end stop to limit rotation of the actuator arm of the valve to limit movement of the flow control member. The position of the mechanical end stop can be changed to change the limit of rotation of the actuator arm.

Actuator for a valve

The actuator of the present disclosure will now be described with reference to figures 1 to 6.

Referring now to fig. 1-3, an actuator 100 is shown according to some embodiments. The actuator 100 is one of a damper actuator, a valve actuator, a fan actuator, and a pump actuator, but is not limited thereto. In various embodiments, the actuator 100 may be a linear actuator (e.g., a proportional linear actuator), a non-linear actuator, a spring return actuator, or a non-spring return actuator.

Actuator 100 includes an actuator body 110. The actuator body 110 houses the various mechanical and processing components of the actuator 100. Additionally, the actuator body 110 facilitates communication between components housed therein and components external to the actuator body 110. The actuator body 110 receives the actuator arm 120 of the valve. A valve is a flow control device for controlling the flow of fluid through a conduit. In some embodiments, the conduit is a pipe or tube. The actuator body 110 is provided with a hole to receive the drive arm 120. In some embodiments, actuator arm 120 enters actuator body 110 from one side of the actuator body and extends from actuator body 110 from the opposite side of the actuator body. In some embodiments, an indicator 130 is mounted on the end of the actuator arm 120 that extends from the actuator body 110 to indicate the position of the flow control member. The placement of the indicator 130 allows an individual or operator to check the position of the flow control member from outside the valve. In some other embodiments, a marker is provided on the actuator body 110 proximate to the indicator 130 such that the indicator 130 is displaced or positioned over or adjacent to the marker. The indicia correspond to the position of the flow control member. Thus, the operator can learn the position of the flow control member by observing the position of the indicator 130 relative to the markings. The indicia may include an open position, a closed position, a percentage open, etc. of the valve. In some other embodiments, actuator 100 includes a sensor for detecting the position of indicator 130. The sensor may be an image sensor, a proximity sensor, or any other suitable sensor for detecting the position of the pointer 130. A controller is provided in communication with the sensor. The controller receives the sensing signals from the sensors, converts the received sensing signals into data, and processes the data to determine the position of the pointer 130. The controller further transmits data relating to the position of the indicator 130 to a user interface located proximate to the valve and/or to a user device located remotely from the valve for displaying the position of the indicator 130. In some other embodiments, the sensor senses the position of the flow control member or the actuator arm of the valve, rather than sensing the position of the indicator. The sensing signal received from the sensor is processed by the controller and the position of the pointer is transmitted to a user interface or user device.

The actuator arm 120 is connected to the flow control member of the valve. For example, the actuator arm 120 is attached to a damper (not shown) of the valve as a flow control member. The damper moves with the drive arm 120. Thus, the actuator arm 120 of the valve is rotated to move the damper to open, close, or partially open the valve.

Actuator 100 includes a stepper motor 140 for moving actuator arm 120. An output shaft 150 of the stepper motor 140 is coupled to the drive arm 120. In one embodiment, the output shaft 150 is coupled to the drive arm 120 via a worm and worm gear mesh. In some embodiments, the actuator body 110 includes a bore 155 to receive the output shaft 150 of the stepper motor 140. Engagement of the output shaft 150 and the drive arm 120 via the worm gear occurs within the actuator body 110. In some embodiments, stepper motor 140 is housed within actuator body 110.

In some embodiments, a worm gear is mounted on the output shaft 150 and meshes with a worm gear mounted on the drive arm 120. In some other embodiments, a worm gear is mounted on the output shaft 150 and engages a worm gear mounted on the drive arm 120.

The torque output of the stepper motor 140 and the size of the worm gear are selected based on the torque requirements. In some embodiments, stepper motor 140 has a torque capability of 1.4N m at 150 RPM. In some embodiments, the gear ratio achieved using the worm gear is as small as 20. In one embodiment of the actuator 100, the worm gear provides high braking torque so that the actuator 100 can remain in a position under high load (e.g., 8N m) when de-energized, thereby mitigating the braking torque requirements of the motor. The use of a stepper motor 140 and worm gear mesh improves the torque capacity of the actuator 100 and the positional accuracy achieved by the actuator 100. In some embodiments, the actuator 100 has a 90 degree stroke, with a full stroke travel time of 2 seconds, i.e., the 90 degree stroke is completed in 2 seconds. In some embodiments, actuator 100 has a torque capacity of 8N m. Further, in some embodiments, the actuator has a position accuracy within 0.1%. For example, the 2 second stroke travel time is calculated as follows to achieve an 8N m output torque and a 90 degree stroke of actuator 100. It is noted that the following calculations are for illustrative purposes only and in no way limit the scope and boundaries of the present disclosure.

TABLE 1

In some embodiments, actuator 100 includes one or more adjustable work stroke stops 160 (e.g., work stroke stops, adjustable stops, mechanical work stroke stops, etc.). The mechanical work stroke limiter 160 limits the movement of the actuator arm 120. The position of the mechanical work stroke limiter 160 may be changed to change the limit of movement to the actuator arm 120. In an embodiment, the actuator 100 includes one or more restraint slots disposed on the actuator body 110 to facilitate movement of the work stroke stop device 160 therethrough. In another embodiment, actuator 100 includes a pair of arcuate retention slots 165 disposed on actuator body 110. In some embodiments, the restraint slot is provided on a bracket attached to the actuator body 110.

In one embodiment of actuator 100, the work stroke limiter comprises a cam and a threaded rod. In some embodiments, the cam is mounted on the drive arm and travel of the cam is limited by a threaded rod. More specifically, the cam strikes the threaded rod and is prevented from moving beyond the limits of the threaded rod. The position of the threaded rod can be adjusted by moving the rod in the arc-shaped limiting groove. In another embodiment, the working stroke limiting means comprises a limit switch.

In some embodiments, actuator 100 includes one or more ultracapacitors provided for storing energy. The super capacitor uses the stored energy for various functions of the actuator 100. In some embodiments, one or more ultracapacitors utilize stored energy to return the actuator to a safe position in the event of a power failure. Due to the use of the super capacitor, the flow control member (e.g. damper in the air volume regulating valve) can be returned to the safe position within 2 seconds.

In some embodiments, the actuator 100 includes a sensorless stall detection unit. In an embodiment, the unit comprises a controller. Referring to fig. 4, a block diagram of the controller 170 in communication with the stepper motor 140 is shown. The controller 170 is adapted to detect a stall of the stepper motor 140 based on the operating voltage of the stepper motor 140. More specifically, the controller 170 monitors the operating voltage of the stepper motor 140. If the operating voltage value exceeds the threshold voltage value, the controller 170 deactivates the stepper motor 140. In an embodiment, the value of the threshold voltage is pre-stored in the memory 200 of the controller 170.

In some embodiments, the controller 170 is a stand-alone controller. In some other embodiments, controller 170 is a controller of a valve coupled to actuator 100. In some other embodiments, controller 170 is a controller of actuator 100 that controls the operation of stepper motor 140 based on instructions received from a user or any other control unit.

The controller 170 includes a processing circuit 180 having a processor 190, a memory 200, and a comparator 220. Processor 190 may be a general or special purpose processor, an Application Specific Integrated Circuit (ASIC), one or more Field Programmable Gate Arrays (FPGAs), a set of processing elements, or other suitable processing elements. Processor 190 is configured to execute computer code or instructions stored in memory 200 or received from other computer-readable media (e.g., CDROM, network storage device, remote server, etc.).

The memory 200 may include one or more devices (e.g., memory units, memory devices, storage devices, etc.) for storing data and/or computer code for performing and/or facilitating the various processes described in this disclosure. Memory 200 may include Random Access Memory (RAM), read Only Memory (ROM), hard drive storage, temporary storage, non-volatile memory, flash memory, optical storage, or any other suitable memory for storing software objects and/or computer instructions. In some embodiments, memory 200 is an Electrically Erasable Programmable Read Only Memory (EEPROM). Memory 200 may include database components, object code components, script components, or any other type of information structure for supporting the various activities and information structures described in this disclosure. Memory 200 may be communicatively connected to processor 190 via processing circuitry 180 and may include computer code for performing (e.g., by processor 190) one or more processes described herein.

The controller 170 is provided with logic for detecting stall in the stepper motor 140. In some embodiments, processor 190 monitors an operating voltage value of stepper motor 140. One of the logic implemented by processor 190 for stall detection is shown in the form of a flow chart 300 in FIG. 5.

Referring to step 310, the value of the threshold voltage is previously stored in the memory 200 of the controller 170. The threshold voltage value is the maximum operating voltage value of the stepper motor 140 up to which the gears and other components of the actuator 100 may operate without damage. In the event that the stepper motor 140 is operating above a threshold voltage value, the stepper motor 140 may tend to stall. The threshold voltage value may be determined by performing a series of experiments to determine a safe voltage value for the stepper motor. The threshold voltage values in the memory 200 are editable and can be changed by the user. In some embodiments, the user interface 210 is configured to receive input from a user to change the threshold voltage value and other parameters stored in the memory 200. The user interface 210 may be implemented using, but is not limited to, one of a touch screen, a Visual Display Unit (VDU), or a computing device in communication with the controller 170.

The controller 170 continuously monitors the operating voltage of the stepper motor 140. Referring to step 320, the controller 170 sets a stall check interrupt. The interrupt enables processor 190 to interrupt the currently executing code and run the code related to stall detection. The controller 170 continuously compares the operating voltage value of the stepping motor 140 with the stored threshold voltage value using the comparator 220. In step 330, control determines whether the operating voltage value of the stepper motor 140 exceeds a threshold voltage value. In the case where the operating voltage value of the stepping motor 140 is lower than the threshold voltage value, the controller 170 continuously compares the operating voltage value of the stepping motor 140 with the threshold voltage value. Referring to step 340, the controller forces the stepping motor 140 to stop in case the operation voltage value of the stepping motor 140 exceeds the threshold voltage value.

In some embodiments, controller 170 operates in two modes, namely "auto-compute on" and "auto-compute off" after stepper motor 140 is deactivated. The mode may be selected by a user. Referring to step 350, the controller 170 determines whether the "auto calculation on" mode or the "auto calculation off" mode is selected. If the "auto calculation on" mode is selected, the controller 170 performs step 360 in which two terminal stop values are recorded. The recorded values are stored in the memory 200. In one embodiment, the end stop values are determined by rotating the shaft of the motor 140 in a clockwise direction and in a counter-clockwise direction to determine two end stop values. If the "auto calculation off" mode is selected, the controller 170 performs step 370 to calculate a difference between the actual position and the terminal stop position. Referring to step 380, the controller 170 determines whether the difference is greater than the stop band value. In the event that the difference is greater than the stop band value, the controller 170 records the associated end stop value and stores the end stop value in the memory 200 (step 390). The stop band value is a predetermined limit value. In some embodiments, the stop band value is 0.15% of the full range of the actuator 100. If the difference is less than the stop band value, the controller 170 returns to step 330.

After performing either step 360 or step 390, the controller 170 returns to step 330 of comparing the operating voltage value of the motor 140 with the stored threshold value.

Controller 170 includes a communication interface 230. Communication interface 230 may be or may include a wired or wireless communication interface (e.g., receptacle, antenna, transmitter, receiver, transceiver, wired terminal, etc.) for data communication with other external systems or devices. In various embodiments, communications via communication interface 230 may be direct (e.g., local wired or wireless communications) or via a communication network (e.g., WAN, internet, cellular network, etc.).

In some embodiments, the user interface 210 is implemented to display data such as stored thresholds, terminal values, and the like.

Referring to fig. 6, an electronic circuit 400 of the actuator assembly is shown. It is noted that the circuit 400 is for illustration purposes only and that the layout of the circuit 400 may vary depending on the application requirements. The circuit 400 is provided with a 24VAC or 24VDC power input 410 that is further provided to a power converter 420. The power converter 420 regulates the 24VAC or 24VDC input to a 24VDC output 430. The circuit 400 is shown to include a supercapacitor 440 for storing electrical energy and releasing energy as needed. The super capacitor 440 converts 24VDC power to 12VDC power when charging and converts 12VDC power to 24VDC power when discharging. A supercapacitor balancing unit 450 is provided to balance the voltage between the supercapacitors 440. The 24VDC load output 430 is provided to a DC-DC converter 460 that regulates the 24VDC power to a 3.3VDC supply that is further provided to a processor 470 and driver IC 480 of the stepper motor 500. One supply line of the 24VDC, 2A output 430 is also connected to the stepper motor driver IC 480 for powering the stepper motor 500. In an embodiment, the stepper motor 500 is the stepper motor 140 shown in fig. 1-3.

Still referring to fig. 6, processor 470 is a low power processor that receives an input signal and provides an output signal 490. The received input signal is processed by a processor 470. The processor 470 controls the operation of the driver IC 480 of the stepper motor 500 based on the received input signals and logic for driving the motor 500. The processor 470 receives feedback signals from the driver IC 480 regarding the function of the motor 500 and further provides output signals. The stepper motor 500 further drives a gear box 510 coupled to the drive arm.

The actuator 100 does not require a sensor (e.g., a position sensor) to determine stall of the stepper motor 140 because the controller 170 determines stall of the motor 140 based on its operating voltage.

Configuration of the exemplary embodiment

The construction and arrangement of the systems and methods as shown in the exemplary embodiments are illustrative only. Although only a few embodiments have been described in detail in this disclosure, many modifications are possible (e.g., variations in sizes, dimensions, structures, shapes and proportions of the various elements, values of parameters, mounting arrangements, use of materials, colors, orientations, etc.). For example, the position of elements may be reversed or otherwise varied, and the nature or number of discrete elements or positions may be altered or varied. Accordingly, all such modifications are intended to be included within the scope of this disclosure. The order or sequence of any process or method steps may be varied or re-sequenced according to alternative embodiments. Other substitutions, modifications, changes, and omissions may be made in the design, operating conditions, and arrangement of the exemplary embodiments without departing from the scope of the present disclosure.

The present disclosure contemplates methods, systems, and program products on any machine-readable media for performing various operations. Embodiments of the present disclosure may be implemented using an existing computer processor, or by a special purpose computer processor in conjunction with a suitable system for this or another purpose, or by a hardwired system. Embodiments within the scope of the present disclosure include program products comprising machine-readable media for carrying or having machine-executable instructions or data structures stored thereon. Such machine-readable media can be any available media that can be accessed by a general purpose or special purpose computer or other machine with a processor. By way of example, such machine-readable media can comprise RAM, ROM, EPROM, EEPROM, CD-ROM or other optical disk storage, magnetic disk storage or other magnetic storage devices, or any other medium which can be used to carry or store desired program code in the form of machine-executable instructions or data structures and which can be accessed by a general purpose or special purpose computer or other machine with a processor. Combinations of the above are also included within the scope of machine-readable media. Machine-executable instructions comprise, for example, instructions and data which cause a general purpose computer, special purpose computer, or special purpose processing machines to perform a certain function or group of functions.

Although the figures show a specific order of method steps, the order of the steps may differ from that depicted. Two or more steps may also be performed simultaneously or partially simultaneously. Such variations will depend on the software and hardware systems chosen and on designer choice. All such variations are within the scope of the present disclosure. Likewise, software implementations could be accomplished with standard programming techniques with rule based logic and other logic to accomplish the various connection steps, processing steps, comparison steps and decision steps.

Claims (7)

1. An actuator for a valve, the actuator comprising:

a stepper motor configured to move a flow control member of the valve; and

a sensorless stall detection unit configured to detect stall of the stepper motor based on an operating voltage of the stepper motor.

2. The actuator of claim 1, wherein the stall detection unit comprises a controller in communication with the stepper motor and configured to receive the operating voltage and compare the operating voltage of the stepper motor to a threshold to determine stall of the stepper motor.

3. The actuator of claim 1, wherein the output shaft of the stepper motor is coupled to the drive arm of the valve via a worm meshing with a worm gear.

4. The actuator of claim 3 further comprising one or more adjustable work stroke stops for limiting movement of the drive arm of the flow control member.

5. The actuator of claim 1, further comprising an ultracapacitor configured to store energy and utilize the stored energy to return the actuator to a safe position.

6. The actuator of claim 1 wherein the actuator has a 90 degree stroke and a torque capacity of 8N-m, with a full stroke travel time of 2 seconds.

7. A method, comprising:

monitoring the working voltage of the stepping motor through a controller;

determining, by the controller, a stall of the stepper motor when the operating voltage exceeds a threshold voltage; and

deactivating the stepper motor after stall is determined.

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