Patent Grant
10011006
The present disclosure relates to a fastener setting algorithm for a drill driver and similar power tools.
Techniques for controlling operation of the drill driver while driving a fastener are readily known. For example, the drill driver may implement an automated fastener setting technique which determines when a fastener reaches a desired stopping position in the workpiece and stops operation of the tool in response thereto. The desired stopping position may be detected, for example by monitoring the motor current behavior or change therein. Sensor signals indicative of the motor current, however, tend to be noisy and thereby lead to inaccuracies in the detection of the desired stopping position. Therefore, it is desirable to develop improved fastener setting techniques that are more immune to noise as compared to conventional methods.
When implementing an automated fastener setting method, it is desirable to avoid false triggers of the electronic clutch. False triggers may occur, for example when the drill bit slips and becomes disengaged from the fastener being driven the by the tool (also referred to as a “cam out” condition). When the drill bit disengages the fastener, the load of the motor will be absent and the motor current will drop rapidly until the drill bit re-engages the fastener. Once the drill bit re-engages the fastener, the motor current will rise up to the proper level. The sudden increase in the motor current may be used to trigger the electronic clutch and thus can cause a false trigger of the electronic clutch following a cam out condition. Therefore, it is also desirable that an automated fastener setting method avoid such false triggers of the clutch.
This section provides background information related to the present disclosure which is not necessarily prior art.
This section provides a general summary of the disclosure, and is not a comprehensive disclosure of its full scope or all of its features.
A method is provided for setting a fastener in a workpiece. The method includes: monitoring a parameter of the power tool during operation of the power tool, where the parameter is indicative of the placement of a fastener being driven by the power tool in relation to the workpiece; detecting a change in the parameter, where the detected change in the parameter indicates that the power tool became disengaged with the fastener; modifying operation of the power tool in response to the detected change in the parameter; subsequently detecting a second change in the parameter; and interrupting transmission of torque to the output spindle in response the detected second change in the parameter, thereby properly setting the placement of the fastener in relation to the workpiece.
In one aspect of this disclosure, the method includes: monitoring current delivered to the electric motor during operation of the tool; detecting an increase in magnitude of the current delivered to the electric motor, where the increase in magnitude exceeds a threshold; continuing to deliver torque to the output spindle when the increase in the current delivered to the electric motor is preceded by a decrease in the current delivered to the electric motor; and interrupting transmission of torque to the output spindle when the increase in the current delivered to the electric motor was not preceded by a decrease in the current delivered to the electric motor, thereby properly setting a fastener driven by the power tool.
Further areas of applicability will become apparent from the description provided herein. The description and specific examples in this summary are intended for purposes of illustration only and are not intended to limit the scope of the present disclosure.
The drawings described herein are for illustrative purposes only of selected embodiments and not all possible implementations, and are not intended to limit the scope of the present disclosure.
Corresponding reference numerals indicate corresponding parts throughout the several views of the drawings.
Referring to
A manually depressible and return biased trigger 28 is provided to initiate and control operation of drill driver 10. Trigger 28 is operated by manually depressing in a trigger engagement direction “A” and returns in a trigger release direction “B” upon release. Trigger 28 is provided in a motor housing 30 that according to several aspects is divisible into individual halves, including a motor housing first half 30a and a motor housing second half 30b which can be made for example of molded polymeric material.
The drill driver 10 may operate in two or more different operating modes as will be further described below. For example, the drill driver 10 may operate in a drill mode and a drive mode. In the drill mode, the amount of torque applied to the output spindle is ignored; this mode is design for drilling applications. There is no speed restriction in this mode. The motor will rotate at maximum speed when the trigger level equals 100%. In an example embodiment, the actual PWM signal duty cycle that drives the motor can be calculated as following: Actual PWM Duty Cycle (PWM DC)=Maximum PWM Duty Cycle (Max PWM DC)×Trigger Level (%), where the Maximum PWM Duty Cycle is 95.6%. Thus, in drill mode, the Actual PWM DC=Max PWM DC×Trigger Level (%)=95.6%×Trigger Level (%).
Drive Mode is intended for driving fasteners and thus the maximum motor speed may be limited. For example, in drive mode, Actual PWM Duty Cycle (PWM DC)=Maximum PWM Duty Cycle (Max PWM DC)×Trigger Level (%)×Power Efficiency (%) (i.e. Actual PWM DC=95.6%×Trigger Level (%)×Power Eff (%)), where the power efficiency (Power Eff) is added in the actual PWM DC calculation for the speed limitation. In an example embodiment, the battery voltage range for the tool operation is between 15V to 21V. When the battery pack of the tool is fully charged (approximately equal to 20.5V), the Power Eff=60%. In this case, the Actual PWM DC=95.6%×60%×Trigger Level (%)=57.4%×Trigger Level (%) when the battery pack is fully charged.
Normally, the performance of the drill driver 10 changes as the battery loses power. For example, at 100% trigger pull (i.e., fully depressed trigger), the speed of the motor will be faster than when the battery voltage is less than fully charged. In other words, the battery level will have an effect on the motor speed of the tool. As a battery is depleted, it takes a higher PWM duty cycle to run the motor at the same speed. To compensate for battery depletion, the Actual PWM duty cycle can be adjusted automatically depending on trigger displacement and the battery level.
According to experimentally measurements, the maximum motor speed in no load condition will drop approximately 5% respect to 1V battery voltage drop. So the maximum motor speed difference between minimum battery voltage and maximum battery voltage will be approximately equal to 30%. In order to maintain the motor in a constant speed regardless of the battery voltage change, the value of the Power Efficiency used to control the motor speed can be changed according the battery voltage level. In the example embodiment, the relationship between battery voltage level and power efficiency is listed in the table below.
When the battery voltage is 20V, the PWM duty cycle (PWM DC) should be 59.5 when the trigger is fully pulled. To keep the motor running at the same speed when the battery voltage is only 15V, the PWM DC at 79.6. While reference is made to particular values, it is readily understood that the values may change depending on the operating parameters of the tool.
Positioned adjacent to trigger 28 is a rotary potentiometer/switch assembly 32. A portion 33b of rotary potentiometer/switch assembly 32 extends freely outwardly from body second half 30b on a second or left hand side of body 12. A similar portion 33a (shown in reference to
Referring to
Rotary potentiometer/switch assembly 32 includes a rotary member 36 in the shape of a circular disk wherein portion 33b extending outward from body 12 is a portion of rotary member 36 extending freely outwardly with respect to body 12 on the left hand side of body 12. The outwardly extending portions 33a, 33b of rotary member 36 allow manual rotation and a side-to-side displacement of rotary member 36 by the user of drill driver 10 from either the right hand side or left hand side of body 12. Rotary member 36 is positioned in a housing space 38 of motor housing 30 providing clearance for both axial rotation of rotary member 36, and side-to-side displacement of rotary member 36 in either a left hand or a right hand displacement such that rotary potentiometer/switch assembly 32 performs at least dual functions as will be described in reference to
A printed circuit board (PCB) 40 is positioned in handle 14. PCB 40 defines an electronic control circuit and includes multiple components including a microcontroller 42 such as a microchip, having a central processing unit (CPU) or the like for performing multiple functions of drill driver 10, at least one electrically erasable programmable read-only memory (EEPROM) function providing storage of data or selected inputs from the user of drill driver 10, and at least one memory device function for storing both temporarily and permanently saved data such as data lookup tables, torque values and the like for use by drill driver 10. According to other aspects (not shown), microcontroller 42 can be replaced by separate components including a microprocessor, at least one EEPROM, and at least one memory device.
Rotary member 36 is rotatable with respect to a rotary member axis of rotation 43. Rotation of rotary member 36 can be in either a first rotational direction “C” or a second rotational direction “D” which is opposite to first rotational direction “C”. It is noted that the rotary member axis of rotation 43 can displace when rotary member 36 is moved in the side-to-side displacement described above and which will be described in greater detail in reference to
Referring to
Referring to
Referring to
With continuing reference to
The electronic control provided by microcontroller 42 and the electronic control circuit of PCB 40 determines multiple operations of drill driver 10. As previously noted, when first directional switch 70 is closed, chuck 20 will operate in a forward or clockwise operating rotational direction. In addition, by subsequent rotation of rotary member 36 following the actuation of first directional switch 70, additional modes of operation of drill driver 10 can be selected, including selecting a speed setting of motor 34, selecting an automatic torque cutout setting, selecting a speed control response, selecting a fastening seating algorithm, and additional modes which will be described later herein. If second directional switch 74 is closed, chuck 20 will be rotated in a reverse or counter-clockwise direction of rotation and subsequent rotation of rotary member 36 can have similar control mode selection features for operation of drill driver 10 in the reverse direction. In addition, the electronic control provided by operation of rotary member 36 and first and second directional switches 70, 74 can also be used to customize the operation of rotary member 36 through a series of operations of rotary member 36 and trigger 28 to suit either a left or right handed user of drill driver 10.
For example, once the user has set a left or right hand mode of operation, subsequent rotation of rotary member 36 can always result in a forward mode being selected such that the operation of drill driver 10 for either a right or left handed operator becomes intuitive for the operator. An advantage of placing rotary member 36 adjacent to handle 14, where the control of rotary member 36 is achieved for example by the thumb of the operator, provides for one-handed operation of drill driver 10, allowing control of multiple modes of operation in a one-handed operation. The same one-handed operation is also permitted by the rotational displacement provided by first and second axles 50, of assembly platform 44 such that physical side-to-side rotational displacement of assembly platform 44 about the axle axis of rotation 54 provides additional functions for the accessible positions of rotary member 36.
Referring to
Referring to
Referring to
In one example, first through sixth LEDs 102-112 can be used to indicate the status of battery 16 as follows. If battery 16 is fully charged and therefore at maximum voltage potential, all of LEDs 102-112 will be illuminated. If battery 16 is at its lowest voltage potential, only first LED 102 will be illuminated. Successive ones of the LEDs, such as first, second and third LEDs 102, 104, 106, will be illuminated when battery 16 is at a capacity greater than the minimum but less than the maximum. The color used for illumination of the LEDs, for example during the battery status display check, can be different from the color used for other mode checks. For example, the battery state of charge indication can illuminate the LEDs using a green color while torque indication can use a blue color.
Referring to
The battery status check can be performed by the operator of drill driver 10 any time operation of drill driver 10 is initiated, and will repeat the steps noted above depending upon the voltage of the battery cells forming battery 16. For the exemplary steps defined in battery state of charge flow diagram 113, the voltage lookup table 142 of
Additional modes of operation for drill driver 10 can be displayed on display port 80 as follows. For example, either forward or reverse direction of operation for chuck 20 can be indicated as follows. When the forward operating mode is selected, first, fifth, and sixth LEDs 102, 110, 112 will be illuminated. When a reverse or counterclockwise rotation of chuck 20 is selected, fourth, fifth, and sixth LEDs 108, 110, 112 will be illuminated. The color selected for indication of rotational direction can vary from the color selected for the battery status check. For example, the color indicated by the LEDs during indication of the rotational direction can be blue or a combination color of blue/green. Similar to the indication provided for the battery status check, a live torque reading selected during rotation of rotary member 36 will illuminate either one or multiple successive ones of the LEDs depending upon the torque level selected. For example, at a minimum torque level only first LED 102 will be illuminated. At a maximum torque level all six of the LEDs 102-112 will be illuminated. Individual ones of the LEDs will successively illuminate as rotary member 36 is axially rotated between the minimum and the maximum torque command settings. Oppositely, the number of LEDs illuminated will reduce successively as rotary member 36 is oppositely rotated, indicating a change in torque setting from the maximum toward the minimum torque command setting. When there are more settings than the number of LEDs available, combination colored LEDs can be illuminated such as blue/green. The LEDs of display port 80 will also perform additional functions related to operation of chuck 20, which will be described in greater detail with reference to clutch operating modes to be further described herein.
In another aspect of this disclosure, the drill driver 10 is configured to operate in different modes. For example, the drill driver 10 may provide an input component (e.g., rotary member 36) that enables the tool operator to select a clutch setting for an electronic clutch. In one embodiment, the operator selects between a drill mode and a drive mode. In a drill mode, the amount of torque applied to the output spindle is ignored and transmission of torque is not interrupted by the controller 42 during tool operation; whereas, in a drive mode, torque applied to the output spindle is monitored by the controller 42 during tool operation. The controller 42 may in turn interrupt transmission of torque to the output spindle under certain tool conditions. For example, the controller may determine when a fastener being driven by the tool reaches a desired stopping position (e.g. flush with the workpiece) and terminate operation of the tool in response thereto without user intervention. It is readily understood that the selected clutch setting can be implemented by the controller 42 with or without the use of a mechanical clutch. That is, in some embodiments, the drill driver 10 does not include a mechanical clutch.
Referring to
Drill selector switch 170 and drive selector switch 172 may be actuated in different sequences to activate other tool operating modes. For example, the drive selector switch 172 may be pushed and held for a fixed period of time (e.g., 0.15 sec) to activate a high torque drive mode; whereas, pushing the driver selector switch 172 twice in the fixed period of time may activate a low torque drive mode. To indicate the different drive modes, the driver selector switch 172 may be lit steady when in the high torque drive mode and blinking when in the low torque drive mode. These two sequences are merely illustrative and other combinations of sequences are envisioned to activate these or other tool operating modes.
An exemplary construct for the display interface is further illustrated in
Referring to
With continuing reference to drill/drive mode flow diagram 177, when driver selector switch 172 is depressed by the user and drive mode 182 is entered, a check is performed to determine if an auto seating flag 196 is indicated. If the auto seating flag 196 is not present, the following step determines if a timed operating system flag 198 is present. If the timed operating system flag 198 is present, in a next duty cycle setting step 200 a timed operating duty cycle is set. Following step 200, motor 34 is turned on for a predetermined time period such as 200 ms (milliseconds) in a timed operating step 202. Following timed operating step 202, in a seating/timed operating flag indication step 204, the control system identifies if both an auto seating flag and a timed operating flag are indicated. If both the auto seating flag and timed operating flag indication step 204 are indicated, operation of motor 34 is stopped in a stop motor running step 206.
Returning to timed operating system flag 198, if the flag is not present, a trigger activation second function 208 is performed which initiates operation of motor 34 in a timed turn on motor start 210. Following this and similar to motor over-current check 188, a motor over-current check 212 is performed. If an over-current condition is not indicated, a first routine 214 algorithm is actuated followed by a selection “on” check 216. If the selection “on” check 216 is negative, a second torque routine 218 algorithm is run, following which if a positive indication is present, returns to the seating/timed operating flag indication; and if negative, returns to the return step 194. If the selection “on” check performed at step 216 is positive, a third routine 220 algorithm is run which if positive thereafter returns to seating/timed operating flag indication step 204 and, if negative, returns to return step 194.
In some embodiments, the drive mode may divided into an automated drive mode and one or more user-defined drive modes, where each of the user-defined drive modes specify a different value of torque at which to interrupt transmission of torque to the output spindle. In the automated drive mode, the controller monitors the current being delivered to the motor and interrupts torque to the output spindle in response to the rate of change of current measures. Various techniques for monitoring and interrupting torque in an automated manner are known in the art, including techniques to setting a fastener in a workpiece, and fall within the broader aspects of the disclosure. An improved technique for detecting when a fastener reaches a desired stopping position is further described below. In such embodiments, it is readily understood that the input component may be configured for selection amongst a drill mode, an automated drive mode and one or more user-defined drive modes.
Referring to
In a selected one of the user-defined drive modes, the controller sets a value of a maximum current threshold in accordance with the selected one of the user-defined drive modes and interrupts torque to the output spindle in response to the current measures exceeding the maximum current threshold. For example, the user selects one of the user-defined drives modes as the desired clutch setting using, for example rotary member 36. Current levels 154 designated as “a”, “b”, “c”, “d”, “e”, “f” correlate to the plurality of predefined torque levels designated as “1”, “2”, “3”, “4”, “5”, “6”, respectively. During tool operation, the controller 42 will act to terminate rotation of the chuck when the current monitored by the controller 42 exceeds the current level associated with the selected user-defined drive mode (i.e., torque setting). The advantage of providing both types of drive modes (i.e., control techniques) within drill driver 10 includes the use of current level increments 154 which, based on prior operator experience, may indicate an acceptable predetermined torque setting for operation of chuck 20 in a specific material. Where the user may not be familiar with the amount of fastener headset in a particular material and/or with respect to a particular sized fastener, the automatic analysis system can be selected, providing for acceptable setting of the fastener which may occur in-between individual ones of the current level increments 154.
In the automated drive mode, the controller can monitor the rate of change in a parameter, such as current delivered to the motor, and interrupt transmission of torque in response to the rate of change of the parameter. While operating a tool in the automated drive mode, it is desirable to avoid false triggers of the electronic clutch. False triggers may occur, for example when the drill bit slips and becomes disengaged from the fastener being driven the by the tool (also referred to herein as a “cam out” condition). With reference to
From the monitored parameter, the controller can determine at 508 when the fastener being driven by the tool reaches a desired position in relation to the workpiece. In other words, the controller can detect when a setting criteria has been achieved. In an exemplary embodiment, the rate of change in motor current indicates the placement of a fastener being driven by the power tool in relation to the workpiece. The controller will monitor the rate of change of the motor current until the setting criteria is reached. When an increase in motor current reaches the setting criteria (e.g., exceeds a threshold), transmission of torque to the output spindle can be interrupted at 509 by the controller, thereby setting the fastener at a desired position in relation to the workpiece; otherwise the controller continues to monitor the motor current as indicated at 502.
The controller can also use the monitored parameter to detect a cam out condition as indicated at 504. In the case of motor current, the cam out condition is indicated by a decrease in the motor current. In response to the detected decrease in motor current, the controller can modify the operation of the power tool as indicated at 506. In one embodiment, the controller could ignore an increase in motor current and continue to deliver torque to the output spindle when the increase in current is preceded by a cam out condition. In this way, the controller can avoid a false trigger of the electronic clutch. In another embodiment, the controller may shift to a different operating mode in response to the detected cam out condition. For example, the controller may decrease the motor speed, thereby enabling the tool operator to re-engage the tool with the fastener. In another example, the controller may pulse the motor on and off such that during the off periods the tool operator can attempt to re-engage the tool with the fastener. It is understood that the controller may initiate other types of corrective actions in response to a detected cam out condition, such as changing an operating parameter or the value of a trigger condition. Such corrective actions also fall within the broader aspects of this disclosure. As noted above, while reference is made to motor current, it is readily understood that the concept set forth below is applicable to other types of tool parameters which may be monitored, including but not limited to rotational speed of the motor, torque on the output spindle, etc. For example, when a load is removed from the motor due to a cam out condition, the rotational speed of the motor will increase quickly for a period of time. Accordingly, the controller is monitoring motor speed, it can determine that a cam out condition has occurred by detecting an increase in motor speed greater than a certain amount within a certain period of time. As another example, torque on the output spindle will decrease quickly in the event of a load being removed from the motor due to a cam out. If the controller is monitoring torque on the output spindle, it can determine a cam out condition if the torque on the output spindle quickly decreases in a particular period of time due to if torque on the output spindle is being measured, such torque will decrease quickly in the event of a load being removed from the motor due to the drill bit becoming disengaged from the fastener and the controller can determine the cam out condition due to detecting a decrease in motor speed of greater than a certain amount in a certain period of time.
Upon detecting a decrease in current that exceeds the cam out threshold, the controller initiates a timer at 524. The timer defines a period of time in which subsequent increase in motor current will be ignored by the controller. In an example embodiment, the timer may count down from 90 ms although other durations fall within the scope of this disclosure.
During duration of the timer, the controller will ignore any increases in motor current as indicated at 525, thereby avoiding a false trigger caused by an increase in the current that was preceded by a cam out condition (i.e., a decrease in the current). In this case, the controller continues to deliver torque to the electric motor.
In the absence of a cam out condition, the controller will compare the magnitude of an increase in current and/or the magnitude of the rate of change to a setting threshold at 526. Transmission of torque to the output spindle is interrupted by the controller at 527 when the increase in the current delivered to the electric motor was not preceded by a decrease in the current delivered to the electric motor and exceeds the setting threshold, thereby properly setting a fastener driven by the power tool. It is to be understood that only the relevant steps of the method are discussed in relation to
Current measures may be digitally filtered before computing the current change rate. In an example embodiment, current is sampled in 15 milliseconds intervals. During each interval, the controller will acquire ten current measures as indicated at 580 and compute an average from the ten measures although more or less measures may be acquired during each interval. The average for a given interval may be considered one current sample and stored in an array of current samples indicated at 582 in
With continued reference to
where n is the number of data points. The intercept will be ignored in this disclosure. For illustration purposes, assume data scatter plot with current values for y of [506,670,700,820,890] corresponding to sample values of [1, 2, 3, 4, 5], such that n=5. Using linear regression, the slope b of the best fit line is equal to 91.8. While a simple linear regression technique has been explained, other linear regression techniques are also contemplated by this disclosure.
Slope of the current measures may be used as the primary indicator for when the fastener has been set at a proper depth in the workpiece. Particularly, by using the slope of the current, the tool is able to determine when the tool is in the HROC (of current) area—shown in the graph of
The slope counter is adjusted in accordance with the comparison of the current slope to the minimum slope threshold. The slope counter is incremented by one when the computed slope exceeds the minimum slope threshold as indicated at 556. Conversely, the slope counter is decremented by one when the computed slope is less than or equals the minimum slope threshold as indicated at 552. When the slope is less than or equal to the minimum slope threshold, the value of the current slope is also set to zero as indicated at 548. In the event the slope counter is equal to zero, the slope counter is not decremented further and the slope counter remains at zero as indicated at 554. Following each adjustment, the value of the slope counter is stored in an array of slope counts as indicated at 586 in
Next, the slope counts are evaluated at 566 in relation to a fastener criteria. The fastener criteria at step 566 includes both a setting criteria, which is indicative of a desired stopping position for the fastener being driven by the tool, and a default criteria. The setting criteria and default criteria may be used together, as shown in 566 of
As noted above, the setting criteria may not use the entire array of values. For example, the array may be designed to hold five slope count values, but the setting criteria may be set such that an increase of counts over a series of four values (e.g. SC2<SC3<SC4<SC5) is sufficient. Other variations regarding the particular number of counts required are also contemplated.
The fastening criteria evaluated at step 566 may also include a default criteria. In some instances, the setting criteria described above with respect to
As with the setting criteria, the series of values may be less than or equal to the number of values stored in the entire array. In this example, slope count values in the array are again compared to each other. The default criteria is met when the slope count values in the array increase from the oldest value to an intermediate peak value and then decrease from the intermediate peak value to the most recent value. For example, the default criteria may be met if SC1<SC2<SC3>SC4>SC5. Of course, other particular default criteria may, be used. For example, the default criteria may require more successive increases or more successive declines than that provided in the example above (e.g., SC1<SC2<SC3<SC4>SC5>SC6>SC7; or SC1<SC2>SC3>SC4; etc). In this embodiment shown in
Torque transmitted to the output spindle is interrupted at 568 when the slope counts meet the setting criteria or default criteria; otherwise, tool operation continues as indicated at 570. Torque may be interrupted in one or more different ways including but not limited to interrupting power to the motor, reducing power to the motor, actively braking the motor or actuating a mechanical clutch interposed between the motor and the output spindle. In one example embodiment, the torque is interrupted by braking the motor, thereby setting the fastener at the desired position. To simulate the electronic clutching function, the user may be subsequently provided with haptic feedback. By driving the motor back and forth quickly between clockwise and counter-clockwise, the motor can be used to generate a vibration of the housing which is perceptible to the tool operator. The magnitude of a vibration is dictated by a ratio of on time to off time; whereas, the frequency of a vibration is dictated by the time span between vibrations. The duty cycle of the signal delivered to the motor is set (e.g., 10%) so that the signal does not cause the chuck to rotate. Operation of the tool is terminated after providing haptic feedback for a short period of time. It is to be understood that only the relevant steps of the technique are discussed in relation to
To integrate the cam out feature into this method, the current drop condition can be determined by monitoring the average current ADC sample data A1 to A5 as described in relation to
In this technique, motor speed is used as a secondary check on whether to interrupt transmission of torque to the output spindle but only when the current slope exceeds a minimum slope threshold. Accordingly, the current slope is compared at 606 to a minimum slope threshold (e.g., with a value of 40). The secondary check proceeds at 608 when the current slope exceeds the minimum slope threshold; otherwise, processing continues with subsequent current sample as indicated at 602.
To perform the secondary check, motor speed is captured at 610. In one example embodiment, motor speed may be captured by a Hall effect sensor disposed adjacent to or integrated with the electric motor. Output from the sensor is provided to the controller. Other types of speed sensors are also contemplated by this disclosure.
In the example embodiment, the controller maintains a variable or flag (i.e., Ref_RPM_Capture) to track when the current slope exceeds the minimum slope threshold. The flag is initially set to false and thereafter remains false while the present slope is less than the minimum slope threshold. At the first occurrence of the current slope exceeding the minimum slope threshold, the flag is false and the controller will set a reference motor speed equal to the present motor speed at 612. The reference motor speed is used to evaluate the magnitude of decrease in motor speed. In addition, the flag is set to true at 613 and will remain set to true until the current slope is less than the minimum slope threshold. For subsequent and consecutive occurrences of the current slope exceeding the minimum slope threshold, the flag remains set to true and reference speed is not reset. In this way, the flag (when set to true) indicates that preceding slope values have exceeded the minimum slope threshold.
Next, the present speed is compared at 614 to the reference speed. When the motor is slowing down (i.e., the reference speed exceeds the present speed), a further determination is made as to the size of the decrease. More specifically, a difference is computed at 615 between the reference speed and the present motor speed. A difference threshold is also set at 616 to be a predefined percentage (e.g., 5%) of the reference speed. The predefined percentage can be derived empirically and may vary for different tool types. The difference is then compared at 617 to the difference threshold. Processing of subsequent current sample continues until the difference between the reference speed and the present speed exceeds the difference threshold as indicated at 617. Once the difference between the reference speed and the present speed exceeds the difference threshold (and while the motor speed is decreasing), transmission of torque to the output spindle is interrupted at 618. It is to be understood that only the relevant steps of the technique are discussed in relation to
Referring to
After completing installation of first fastener 224 such that fastener head 228 contacts component surface 230, it is often desirable to install a second or more fasteners to couple the first and second components 226, 227. Referring to
Referring to
The feedback provided to the user can be manipulated as follows. First, the output of motor 34 can be stopped. Second, the speed of motor 34 can be reduced. For example, the speed of motor 34 can be reduced from approximately 600 rpm to approximately 200 rpm. This reduction in operating speed provides the user with visible feedback on the rate at which the fastener is being installed and provides additional time for the user to respond to how far fastener 224′ is being set into the first and second components 226, 227. Third, operation of motor 34 can be ratcheted, for example by pulsing motor 34 on and off to provide discreet, small rotations of the fastener 224′. This acts to slow down the average rotation speed of chuck 20, providing the user more control in setting the depth of penetration of fastener 224′. This could also function as an indication to the user that fastener installation is nearly complete and that the drill driver 10 has changed operating mode. In addition, ratcheting of motor 34 also provides a sensation to the user similar to a mechanical clutch operation. Fourth, the varied output of motor 34 from the above second and third operations can continue indefinitely or could continue for a fixed period of time and then stop. For example, the varied output of motor 34 can continue until the user releases trigger 28.
With continuing reference to
Referring again to
Referring to
Returning to the first comparison step 254, if the switch hold counter is less than the normal hold counter, a decrease counter step 258 is performed wherein the timed operation time delay counter is decreased. Returning to the second comparison step 256, if the switch hold counter is greater than the normal hold counter, an increase counter step 260 is performed wherein the timed operation time delay counter is increased. Following either the decrease counter step 258 or the increase counter step 260, the timed operation mode is timed-out.
Referring to
If drill driver 10 is preset to operate in an automatic operating mode, the timed operation mode can be automatically induced when the electronic control system identifies that motor 34 has stopped rotation, for example due to either the maximum current or torque setting being reached, while the user continues to depress trigger 28. After the determination that motor 34 has stopped for a predetermined period of time while trigger 28 is still depressed, the timed operation mode automatically begins and will rotate motor 34 and chuck 20 for approximately 200 ms. The predetermined time period for automatic initiation of the timed operation mode can also be for example one second, or set to any other desired time period.
If drill driver 10 is set to operate in the manual mode and the rotary potentiometer/switch assembly 32 is used to predetermine or preset an operating torque via a torque command for chuck 20, motor 34 will stop when the predetermined torque setting is reached. If the user releases trigger 28 at this time, and then re-depresses trigger 28 within a predetermined period of time, a last saved high current level required to fully seat a fastener, saved for example in the EEPROM or memory device/function of microcontroller 42, will be automatically reapplied, thereby further rotating chuck 20 until the high current level last saved in memory is achieved. This permits a combination of a manual and an automatic operation of drill driver 10 such that the predetermined or preset torque limits manually entered by the user can be supplemented automatically by a current level saved in the memory corresponding to a fully set fastener position.
Referring to
Referring to
Following the stop motor running operation 286, a first check button step 290 is performed wherein it is determined if a forward operational selection button or switch is actuated. If the first check button step 290 is positive, a set forward mode step 292 is performed. If the first check button step 290 is negative, a second check button step 294 is performed, wherein it is determined if a reverse operational selection button or switch has been actuated. If the second check button step 294 is positive, a set reverse mode step 296 is performed. If the second check button step 294 is negative, a third check button step 298 is performed wherein a determination is made if the drive mode button or drive mode selector is actuated. If the third check button step 298 is positive, a set drive mode step 300 is performed. If the third check button step 298 is negative, a fourth check button step 302 is performed wherein it is determined if the drill mode button or drill mode selector is actuated. If the result of the fourth check button step 302 is positive, a set drill mode step 304 is performed. If the fourth check button step 302 is negative, a clear flag step 306 is performed wherein an auto seating flag is set to zero.
Returning to the check status step 282, if any of the items checked are indicated, a stop motor step 308 is performed to stop operation of motor 34. Following the stop motor step 308, a saved step 310 is performed wherein last data received, such as a maximum operating torque or operating current, is saved to the EEPROM of microcontroller 42. Following saved step 310, a power off step 312 is performed turning off operating power to drill driver 10 and enter sleep mode step 314 is performed following the power off step 312 to save electrical battery energy of drill driver 10.
Referring to
Referring to
Referring to
According to several aspects, axial rotation of rotary member 36 provides twelve individual torque settings. In a first torque select step 356, a determination is made if the selected torque input corresponds to torque setting 12. If step 356 is affirmative, in a setting torque step 358, a torque level of 20 amps is set. At this time, in a step 360, green LED represented by sixth LED 112 is illuminated. If the result of step 356 is negative, in a following step 362, a determination is made if the selected torque input corresponds to torque setting 11. If affirmative, in a step 364, a torque of 18.5 amp level is set. At this same time, the color of sixth LED 112 is changed from green to blue in a step 366. If the response from step 362 is negative in a step 368, a determination is made if the selected torque input corresponds to torque setting 10. If the answer is affirmative, in a step 370, a torque level of 17 amps is set. At this time, the fifth LED 110 is illuminated using a green color in a step 372. If the response to step 368 is negative, in a step 374, a determination is made if the selected torque input corresponds to torque setting 9. If the response is affirmative, in a step 376, a torque of 15.5 amp level is set. At this time, fifth LED 110 is changed from green to blue in a step 378. If the response from step 374 is negative, in a step 380, a determination is made if the selected torque input corresponds to torque setting 8. If affirmative, in a step 382, a torque level of 14 amps is set. At this time, the fourth LED 108 is illuminated using a green color in a step 384. If the response from step 380 is negative, in a step 386, a determination is made if the selected torque input corresponds to torque setting 7. If affirmative, in a step 388, a torque of 12.5 amp level is set. At this time, the fourth LED 108 is changed from green to a blue color in a step 390. If the response to step 386 is negative, in a step 392, a determination is made if the selected torque input corresponds to torque setting 6. If affirmative, in a step 394, a torque of 11 amp level is set. At this time, the third LED 106 is illuminated using a green color in a step 396. If the response from step 392 is negative, in a step 398, a determination is made if the selected torque input corresponds to torque setting 5. If affirmative, in a step 400, a torque of 9.5 amp level is set. At this time, the third LED 106 is changed from a green to a blue color in a step 402. If the response to step 398 is negative, in a step 404, a determination is made if the selected torque input corresponds to torque setting 4. If affirmative, in a step 406, a torque of 8 amp level is set. At this time, the second LED 104 is illuminated using a green color in a step 408. If the response to step 404 is negative, in a step 410, a determination is made if the selected torque input corresponds to torque setting 3. If affirmative, in a step 412, a torque of 6.5 amp level is set. At this time, the second LED 104 is changed from a green to a blue color in a step 414. If the response to step 410 is negative, in a step 416, a determination is made if the selected torque input corresponds to torque setting 2. If affirmative, in a step 418, a torque of 5 amp level is set. At this time, the first LED 102 is illuminated using a green color in a step 420. If the response to step 416 is negative, in a step 422, a determination is made if the selected torque input corresponds to torque setting 1. If affirmative, in a step 424, a torque of 3.5 amp level is set. At this time, the first LED 102 is changed in color from green to blue in a step 426. It is noted that the sequencing identified in clutch torque flow diagram 351 corresponds to a decreasing torque value manually set by the user. The sequence is reversed if the user is selecting torque values that increase in value.
Referring to
Referring to
An opposite operation starting with illumination of sixth LED 112 and continuing to first LED 102 occurs if the reverse step 436 is actuated. Following reverse step 436, sixth LED 112 is illuminated in a blue color in a step 464. Following a delay of 60 ms in a step 466, the sixth LED 112 is turned off and the fifth LED 110 is turned on in a blue color in a step 468. Following a delay of 60 ms in a step 470, the fifth LED 110 is turned off and the fourth LED 108 is turned on in a blue color in a step 472. Following a delay of 60 ms in a step 474, the fourth LED 108 is turned off and the third LED 106 is turned on in a blue color in a step 476. Following an additional delay of 60 ms in a step 478, the third LED 106 is turned off and the second LED 104 is turned on in a blue color in a step 480. Following a delay of 60 ms in a step 482, the second LED 104 is turned off and the first LED 102 is turned on in a blue color in a step 484. Finally, following a delay of 60 ms in a step 486, the first LED 102 is turned off in a step 488. Based on the sequence of operation of sixth through first LEDs 112-102 in the reverse operating mode, the LEDs will appear to rapidly illuminate in a counter-clockwise direction.
One of the drawback of the LED-based display described above is that the clutch setting is not quantified for the tool operator. An alternative display 700 for a drill driver 10 having an electronic clutch is shown in
For drill drivers having multi-speed transmissions, the maximum clutch torque setting for the mechanical clutch is dictated by the maximum torque that can be achieved in a high speed (low torque) setting. Setting the maximum torque setting for the clutch in this manner prevents the tool from stalling regardless of the speed and clutch settings but creates a difference in the maximum torque setting between low speed and high speed modes. In an electronic clutch, different ranges of clutch settings can be assigned to each of the different speed settings. For example, in a high speed (low torque) setting, the clutch settings may range between eight settings (i.e., 1-8); whereas, in the low speed (high torque) setting, the clutch setting may range between twelve settings (i.e., 1-12), where for clutch setting correlates to a different user selectable predefined maximum torque level as noted above. To support this arrangement, the clutch settings are display by the controller on the display 700 using different scales. When the tool is in the low speed setting, all twelve clutch settings can be selected by the user and thus may be displayed on the display. When the tool is in the high speed setting, only the first eight settings (i.e., 1-8) are selected by the user and thus may be display on the display. In some embodiments, the clutch setting mechanism (e.g., rotary member 36) enables the user to pick from the full range of settings (e.g., 12 different settings). In the case the tool is in the high speed setting, values for the first eight setting are displayed as well as the value for the eight setting being displayed for the four additional setting available on the clutch setting mechanism. That is, values for the twelve selectable setting, of the rotary member are displayed as 1, 2, 3, 4, 5, 6, 7, 8, 8, 8, 8, 8, respectively. While reference is made to a drill driver with two speed transmission, it is readily understood that this concept may be extended to three or more speed transmissions as well.
Example embodiments are provided so that this disclosure will be thorough, and will fully convey the scope to those who are skilled in the art. Numerous specific details are set forth such as examples of specific components, devices, and methods, to provide a thorough understanding of embodiments of the present disclosure. It will be apparent to those skilled in the art that specific details need not be employed, that example embodiments may be embodied in many different forms and that neither should be construed to limit the scope of the disclosure. In some example embodiments, well-known processes, well-known device structures, and well-known technologies are not described in detail.
The terminology used herein is for the purpose of describing particular example embodiments only and is not intended to be limiting. As used herein, the singular forms “a,” “an,” and “the” may be intended to include the plural forms as well, unless the context clearly indicates otherwise. The terms “comprises,” “comprising,” “including,” and “having,” are inclusive and therefore specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof. The method steps, processes, and operations described herein are not to be construed as necessarily requiring their performance in the particular order discussed or illustrated, unless specifically identified as an order of performance. It is also to be understood that additional or alternative steps may be employed.
The foregoing description of the embodiments has been provided for purposes of illustration and description. It is not intended to be exhaustive or to limit the disclosure. Individual elements or features of a particular embodiment are generally not limited to that particular embodiment, but, where applicable, are interchangeable and can be used in a selected embodiment, even if not specifically shown or described. The same may also be varied in many ways. Such variations are not to be regarded as a departure from the disclosure, and all such modifications are intended to be included within the scope of the disclosure.
This application claims the benefit of U.S. Provisional Application No. 61/863,537 filed on Aug. 8, 2013. The entire disclosure of the above application is incorporated herein by reference.
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