The present disclosure relates to torque tools, and more particularly, to determining a torque applied by a power tool to a fastener.
Torque tools are commonly used in industrial settings to tighten fasteners to a specified torque. However, determining the actual torque applied by a power tool to a fastener can be difficult and inaccurate. Although determining the actual torque applied can be difficult for all power tools, impact wrenches are particularly difficult to accurately determine the actual torque applied to a faster. On the other hand, impact wrenches have several advantages over other torque tools, including a compact size, low tool weight and low cost. Thus, improved techniques for accurately determining the torque applied to a fastener would be desirable.
An improved power tool with torque control is described. The power tool estimates torque applied to a fastener by measuring the angle of rotation of the fastener and the energy expended by the tool to rotate the fastener through the angle of rotation. The power tool improves on the torque estimation by considering the efficiency of energy expended by the drive mechanism which may result in less energy (or more) being transferred to the fastener. The tool may also include any other aspect described below in the written description or in the attached drawings and any combinations thereof.
The Detailed Description is described with reference to the accompanying figures. The use of the same reference numbers in different instances in the description and the figures may indicate similar or identical items.
Aspects of the disclosure are described more fully hereinafter with reference to the accompanying drawings, which form a part hereof, and which show, by way of illustration, example features. The features can, however, be embodied in many different forms and should not be construed as limited to the combinations set forth herein; rather, these combinations are provided so that this disclosure will be thorough and complete, and will fully convey the scope. The following detailed description is, therefore, not to be taken in a limiting sense.
Estimating the torque applied to a joint resulting from a fastening operation involving discrete blows may use measurements of the angular position of the joint and the change in angular position of the joint with each blow. This information may be coupled with knowledge of the energy in the impact mechanism before and after the blow. Ideally, if the energy leaving the tool in a given blow is measured, the mean torque multiplied by the change in joint angle will be equal to the energy output. Thus, if both the change in joint angle and the amount of energy leaving the tool during each blow are known, the joint torque can be estimated. That is, for a particular blow, the estimated mean joint torque can be determined from the energy that leaves the tool divided by the change in angular position of the threaded joint. It is noted, however, that other schemes involving assumptions about the joint's torque-versus-angle characteristic can also be used in conjunction with angle and energy measurements to estimate joint torque.
Angular position sensors may be placed on the anvil and on the hammer of an impact wrench to determine changes in angle rotation of the output shaft of the tool during a fastener tightening operation. This allows an approximation of the joint angular position and, via differentiating the hammer angular position, provides an estimate of the hammer angular velocity before and after an impact. The velocity change may then be used to determine the change in energy during an impact. That is, the velocity of the hammer will slow due to the impact force, which represents energy which is transferred from the hammer to the output shaft during the impact.
Various sensors may be used to improve torque estimates. A gyro is one type of sensor that may be used for the purpose of compensating for angular motion of the tool when computing angular rotation of the joint. A gyro may also be used to provide housing velocity information. A sudden change in the housing velocity following an impact indicates energy transfer from the mechanism to the housing. In an embodiment, this energy should be subtracted from that assumed to be utilized in tightening the joint. Various other sensors may also be used to improve estimates of joint torque based on tracking energy changes in addition to tracking the energy change of the impacting hammer. That is, additional and/or alternative sensors may be used to capture other energy that is lost and not transferred to the joint. For example, thermocouples may be used to measure the temperature of elements of the power tool, and thus, track changes in the thermal energy due to impact. This is particularly valuable for the impacting members themselves, but may also be extended to other parts of the tool as well. Accelerometer signals may also be integrated to determine the velocity of various components, allowing for the determination of energy associated with movement and vibration. Frequency analysis of accelerations may also be used in conjunction with peak values and analytical modal analysis to determine energies in vibratory modes excited by the impacts. Additional position sensors (e.g., angular and linear) may also be used to measure deformation and hence potential energy of tool components. Strain gauges may be used for a similar purpose. Other sensors that may be used include torque transducers, motor encoders/resolvers, and current and voltage probes. While the sensors mentioned above may be used for an improved torque estimation, it is understood that many other sensors may also be used to estimate energy changes. While the improved torque measurement methods herein are particularly useful with discrete energy tools like impact wrenches, it is understood that the energy tracking and angular measurement methods described herein may also be applied to continuous energy delivery tools.
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In general, controller 60 is configured to receive one or more sensor measurements (i.e., electrical signals) corresponding to the one or more sensors of power tool 10. Controller 14 then determines an estimated torque output (utilizing any one of the energy value formulas disclosed herein) of the power tool 10 based on the one or more sensors. In embodiments, controller 60 is communicatively coupled to operatively control motor 12 based on the determined estimated torque value. For example, controller 60 may control power (e.g., throttle motor current, throttle motor voltage, motor timing, etc.) to the motor 12 when the estimated torque T applied to the nut 28 satisfies the preset torque setting to ensure proper tightening of the nut 28.
Although the above formula may be used as a basic estimate of torque applied to a fastener 28, the formula assumes perfect energy transfer from the drive mechanism 16 to the nut 28 and does not account for the efficiency of such energy transfer. Thus, an improved formula would adjust the energy value based on energy losses (or contributions) that change the actual energy transferred to the nut 28. Thus, the energy value in the above formula may be substituted with an actual energy as determined by the following formula:
Energy estimates may be made for each of the above energy values using a variety of sensors. Therefore, the energy formula above may be rewritten in terms of the sensors that may be used to estimate energy losses (or contributions) to be subtracted from the energy of the hammer 16. Thus, the rewritten formula may be:
It is understood that the above formulas may be modified as desired for a particular power tool. For example, it is possible to apply a factor to one or more energy values where it is determined that only a portion of the estimated energy associated with a condition or sensor is attributable to an energy loss (or contribution) transferred from the drive mechanism 16 to the output shaft 22. It is also possible that a smaller or greater number of conditions or sensors may be included in the actual energy estimate. Multiple sensors of the same type may also be used in various locations of the power tool 10 to improve the actual energy estimate. Further, multiple sensors may be used together to determine a particular energy estimate.
In embodiments, controller 60 is communicatively coupled to an angle sensor 62 and one or more sensors 64. Examples of sensors that may be used to estimate energy losses (or contributions) are shown in
The controller 60 may comprise a processor configured to execute computer readable program instructions (i.e., control logic) from a non-transitory carrier medium (e.g., storage medium such as a flash drive, solid-state disk drive, SD card, or the like). The program instructions, when executing by the processor, can cause the controller 60 to control the power tool 10 (e.g., controlling power supplied to motor 12). In an implementation, the program instructions form at least a portion of software programs for execution by the processor.
The processor provides processing functionality for the controller 60 and power tool 10 and may comprise any number of processors, micro-controllers, or other processing systems, and resident or external memory for storing data and other information accessed or generated by the computing system. The processor is not limited by the materials from which it is formed or the processing mechanisms employed therein.
The non-transitory carrier medium is an example of device-readable storage media that provides storage functionality to store various data associated with the operation of the controller 60, such as firmware, a software program, code segments, or program instructions, or other data to instruct the processor and other elements of the controller 60 and power tool 10 to perform the methods described herein. The carrier medium may be integral with the processor, stand-alone memory, or a combination of both. The carrier medium may include, for example, removable and non-removable memory elements such as RAM, ROM, Flash (e.g., SD Card, mini-SD card, micro-SD Card), USB memory devices, and so forth. In embodiments of the computing system, the carrier medium may include removable ICC (Integrated Circuit Card) memory such as provided by SIM (Subscriber Identity Module) cards, USIM (Universal Subscriber Identity Module) cards, UICC (Universal Integrated Circuit Cards), and so on.
The power tool 10 may be monitored and/or controlled by one or more computing systems that may communicate with the controller 60. The one or more computing systems can be connected to the controller 60 of the power tool 10, either by direct connection, or through one or more network connections (e.g., local area networking (LAN), controller area network (CAN), etc.), wireless area networking (WAN or WLAN), one or more hub connections (e.g., USB hubs), and so forth). For example, the one or more computing systems can be communicatively coupled (e.g., hard-wired or wirelessly) to the controller 60 of the power tool 10.
In some embodiments, the power tool 10 may further include one or more input/output (I/O) devices (e.g., a trigger, a keypad, buttons, a display/touchscreen, a speaker, etc.) that communicate with the controller 60 to allow a user to operate and control settings of the power tool 10.
The controller 60 may also include a communication device to permit the controller 60 to send/receive data over the one or more networks. The communication device may, for example, comprise a transmitter and/or receiver; data ports; software interfaces and drivers; networking interfaces; data processing components; and so forth.
The one or more networks are representative of a variety of different communication pathways and network connections which may be employed, individually or in combinations, to facilitate communication between external computing devices and the controller 60 of the power tool 10. Thus, the one or more networks may be representative of communication pathways achieved using a single network or multiple networks. Further, the one or more networks are representative of a variety of different types of networks and connections that are contemplated including, but not necessarily limited to: the Internet; an intranet; a Personal Area Network (PAN); a Local Area Network (LAN) (e.g., Ethernet); a Wide Area Network (WAN); a satellite network; a cellular network; a mobile data network; wired and/or wireless connections; and so forth. Examples of wireless networks include but are not necessarily limited to: networks configured for communications according to: one or more standard of the Institute of Electrical and Electronics Engineers (IEEE), such as 802.11 or 802.16 (Wi-Max) standards; Wi-Fi standards promulgated by the Wi-Fi Alliance; Bluetooth standards promulgated by the Bluetooth Special Interest Group; and so on. Wired communications are also contemplated such as through Universal Serial Bus (USB), Ethernet, serial connections, and so forth.
While various embodiments of the power tool 10 have been described, it should be understood that the embodiments are not so limited, and modifications may be made without departing from the embodiments herein. While each embodiment described herein may refer only to certain features and may not specifically refer to every feature described with respect to other embodiments, it should be recognized that the features described herein are interchangeable unless described otherwise, even where no reference is made to a specific feature. It should also be understood that the advantages described above are not necessarily the only advantages of the tool, and it is not necessarily expected that all of the described advantages will be achieved with every embodiment of the tool. Other examples may occur to those skilled in the art based on the present disclosure. Such other examples are intended to be within the scope of the present disclosure.
In reading the claims, it is intended that when words such as “a,” “an,” “at least one,” or “at least one portion” are used there is no intention to limit the claim to only one item unless specifically stated to the contrary in the claim. When the language “at least a portion” and/or “a portion” is used the item can include a portion and/or the entire item unless specifically stated to the contrary. Unless specified or limited otherwise, the terms “mounted,” “connected,” “supported,” and “coupled” and variations thereof are used broadly and encompass both direct and indirect mountings, connections, supports, and couplings. Further, “connected” and “coupled” are not restricted to physical or mechanical connections or couplings.
Number | Date | Country | |
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Parent | 17064764 | Oct 2020 | US |
Child | 18914831 | US |