ELECTRONIC CLUTCH FOR POWER TOOL

A power tool includes a housing; an electric motor; an electronic clutch; and a clutch setting assembly that includes a variable resistive element, a clutch selector, and a contact assembly. The contact assembly includes a spring coupled to the clutch selector and a contact member with a leg configured to be insertable into an opening in the clutch selector so that the spring and the contact member are non-removable from the clutch selector and the spring biases the contact member against the variable resistive element. The contact member has a head configured to engage the variable resistive element to generate a resistance signal that corresponds to a position of the clutch selector. The controller is configured to receive the resistance signal and, based on the resistance signal, look-up, receive, or generate the torque threshold value for the power tool operation parameter that corresponds to the selected clutch setting.

FIELD

The present patent application relates to power tools and electronic clutches/mechanisms for power tools.

BACKGROUND

Many power tools, such as power drills, power drivers, power fastening tools and/or other power tools, have a mechanical clutch that interrupts power transmission to the output spindle/shaft when the output torque exceeds a threshold value of a maximum torque. U.S. Pat. No. 9,494,200, which is incorporated by reference in the patent application in its entirety, provides an exemplary prior art mechanical clutch. Such a mechanical clutch is a purely mechanical device that breaks a mechanical connection in the transmission to prevent torque from being transmitted from the motor to the output spindle/shaft of the power tool. Clutches or slip clutches are generally used in the power tools to provide torque limited application at the working bit. Traditional slip clutches have been executed mechanically with balls, springs, and clutch plates. In these mechanical clutches, the maximum torque threshold value may be user adjustable, often by a clutch collar that is attached to the power tool between the power tool and the tool holder/chuck. The user may rotate the clutch collar among a plurality of different positions for different maximum torque settings. The components of the mechanical clutches, however, tend to wear over time, and add excessive bulk and weight to a power tool.

In order to save length and cost, some power tools additionally or alternatively include an electronic clutch. Such an electronic clutch electronically senses the output torque (e.g., via a torque transducer) or infers the output torque (e.g., by sensing another parameter such as current drawn by the motor). U.S. Pat. No. 10,220,500 (“the ‘500 Patent”), which is incorporated by reference in the present patent application its entirety, provides an exemplary prior art electronic clutch. When the electronic clutch determines that the sensed output torque exceeds a threshold value, it interrupts or reduces power transmission to the output shaft/spindle, either mechanically (e.g., by actuating a solenoid to break a mechanical connection in the transmission) or electrically (e.g., by interrupting or reducing current delivered to the motor, and/or by actively braking the motor).

For example, the electronic clutch (e.g., like the one in the ‘500 Patent) includes a rotatable clutch collar for selecting the clutch setting. The controller for the electronic clutch needs to know the position of the rotatable clutch collar in order to adjust the clutch setting. As shown inFIG.7of the ` 500 Patent, the clutch setting is sensed using a sensor/stationary membrane potentiometer. A spring70is heat-staked to the clutch collar and rotates along with the clutch collar. The spring70includes a stylus-type projection that is pressed against the stationary membrane potentiometer. Depending on the rotational position of the clutch collar and the spring70, the stylus-type projection of the spring70engages a different location of the stationary membrane potentiometer. Thus, the resistance in the membrane potentiometer would change and the controller could sense the rotational position of the clutch collar. Various improvements to this design are desired.

SUMMARY

The present patent application provides improvements in the clutches for power tools.

One aspect of the present patent application provides a power tool. The power tool comprises a housing, an output spindle, an electric motor, an input switch for actuating the electric motor, an electronic clutch, and a clutch setting assembly. The electric motor is disposed in the housing and is configured to provide torque to the output spindle. The electronic clutch includes a sensor and a controller. The sensor of the electronic clutch is configured to sense a power tool operation parameter. The controller of the electronic clutch is coupled to the sensor and is configured to initiate a first protective operation to interrupt or reduce transmission of torque from the electric motor to the output spindle when the sensed power tool operation parameter exceeds a torque threshold value. The clutch setting assembly includes a variable resistive element, a clutch selector, and a contact assembly. The variable resistive element has a variable resistance and is coupled to the housing. The clutch selector is movable relative to the housing to select a clutch setting. The contact assembly includes a contact member and a spring non-removably coupled to the clutch selector with the spring biasing the contact member against the variable resistive element. The contact member has a head configured to engage the variable resistive element to generate a resistance signal that corresponds to a position of the clutch selector. The controller is configured to receive the resistance signal and, based on the resistance signal, is configured to look-up, receive, or generate the torque threshold value for the power tool operation parameter that corresponds to the selected clutch setting. In one embodiment, the head may include an asymmetrical shaped configuration. In one embodiment, the contact member may be a contact pin. In one embodiment, the head may include a projection disposed thereon, and the projection may be configured to engage the variable resistive element to generate the resistance signal that corresponds to the position of the clutch selector.

Another aspect of the present patent application provides a power tool. The power tool comprises a housing; an output spindle; an electric motor disposed in the housing and configured to provide torque to the output spindle; an input switch for actuating the electric motor; an electronic clutch; and a clutch setting assembly. The electronic clutch includes a sensor configured to sense a power tool operation parameter and a controller that is coupled to the sensor and is configured to initiate a first protective operation to interrupt or reduce transmission of torque from the electric motor to the output spindle when the sensed power tool operation parameter indicates that an output torque has exceeded a torque threshold value. The clutch setting assembly includes a variable resistive element with a variable resistance coupled to the housing, a clutch selector movable relative to the housing to select a clutch setting, and a contact assembly coupled to the clutch selector. The contact assembly includes a spring coupled to the clutch selector and a contact member with a shaft configured to be insertable into an opening in the clutch selector so that the spring and the contact member are non-removable from the clutch selector and the spring biases the contact member against the variable resistive element. The contact member has a head configured to engage the variable resistive element to generate a resistance signal that corresponds to a position of the clutch selector. The controller may be configured to receive the resistance signal and, based on the resistance signal, look-up, receive, or generate the torque threshold value for the power tool operation parameter that corresponds to the selected clutch setting.

Implementations of the foregoing aspects may include one or more of the following features. The head may include a projection disposed thereon. The projection may be configured to engage the variable resistive element to generate the resistance signal that corresponds to the position of the clutch selector.

The variable resistive element may be non-movable relative to the housing.

The clutch selector may comprise a collar rotatably coupled to the housing and rotation of the collar changes the selected clutch setting.

The spring may be received within an opening in the clutch selector and a leg of a spring keeper may be received within the spring.

The power tool may comprise a second spring that may be received in a second opening in the clutch selector.

The clutch selector may include a spring keeper coupled to the spring and the contact member coupled to the spring keeper. The contact member may be moveable relative to the spring keeper to non-removably retain the spring, the spring keeper, and contact member relative to the clutch selector.

The spring keeper may comprise a leg and the contact member includes the shaft and the head.

The shaft of the contact member may include a key and the clutch selector includes a slot, whereby rotation of the contact member causes the key to engage the slot to retain the contact member in the clutch selector.

The shaft of the contact member may be configured to be snap fit into the opening of the clutch selector.

The shaft of the contact member may include a catch configured to engage an undercut in the opening of the clutch selector.

The opening of the clutch selector may comprise a plurality of openings and a leg of a spring keeper comprises a plurality of legs received in the plurality of openings

The sensor may include a rotation sensor that is configured to sense changes in an angular position of an output shaft of the motor and to provide a sensing signal corresponding to angular rotation, speed, and/or acceleration of the motor to the controller.

The first protective operation may include at least one of interrupting power to the motor, reducing power to the motor, braking the motor, and actuating a mechanical clutch element.

The variable resistive element may include a plurality of conductive elements circumferentially spaced apart on the variable resistive element. The resistance of the variable resistive element may change when pressure is applied by the portion of the contact assembly on one of the plurality of conductive elements disposed along the variable resistive element.

Another aspect of the present patent application provides a system. The system comprises a housing, an electronic clutch, and a clutch setting assembly. The electronic clutch includes a sensor configured to sense an operation parameter of the system and a controller. The controller is coupled to the sensor and is configured to initiate a first protective operation to interrupt or reduce transmission of torque from an electric motor to an output spindle when the sensed operation parameter exceeds a torque threshold value. The clutch setting assembly includes a variable resistive element with a variable resistance coupled to the housing, a clutch selector movable relative to the housing to select a clutch setting, and a contact assembly including a contact member and a spring non-removably coupled to the clutch selector with the spring biasing the contact member against the variable resistive element. The contact member has a head configured to engage the variable resistive element to generate a resistance signal that corresponds to a position of the clutch selector. The controller is configured to receive the resistance signal and, based on the resistance signal, look-up, receive, or generate the torque threshold value for the operation parameter that corresponds to the selected clutch setting. In one embodiment, the head may include an asymmetrical shaped configuration. In one embodiment, the contact member may be a contact pin. In one embodiment, the head may include a projection disposed thereon, and the projection may be configured to engage the variable resistive element to generate the resistance signal that corresponds to the position of the clutch selector.

Another aspect of the present patent application provides a power tool. The power tool comprises a housing; an output spindle; an electric motor disposed in the housing and configured to provide torque to the output spindle; an input switch for actuating the electric motor; an electronic clutch; and a clutch setting assembly. The electronic clutch includes a sensor configured to sense a power tool operation parameter and a controller coupled to the sensor and configured to initiate a first protective operation to interrupt or reduce transmission of torque from the electric motor to the output spindle when the sensed power tool operation parameter indicates that an output torque has exceeded a torque threshold value. The clutch setting assembly includes a variable resistive element with a variable resistance coupled to the housing, a clutch selector movable relative to the housing to select a clutch setting, and a contact assembly coupled to the clutch selector. The contact assembly includes a spring coupled to the clutch selector and a contact member configured to be snap-fit with the clutch selector, so that the contact member is non-reversibly non-removable from the clutch selector and the spring biases the contact member against the variable resistive element. The contact member has a head configured to engage the variable resistive element to generate a resistance signal that corresponds to a position of the clutch selector. The controller is configured to receive the resistance signal and, based on the resistance signal, look-up, receive, or generate the torque threshold value for the power tool operation parameter that corresponds to the selected clutch setting.

Implementations of the foregoing aspects may include one or more of the following features. The contact member may include a shaft received in an opening in the clutch selector and a catch coupled to the shaft configured to engage an undercut in the opening.

Another aspect of the present patent application provides a system. The system comprises a housing and clutch setting assembly. The clutch setting assembly includes a variable resistive element with a variable resistance coupled to the housing, a clutch selector movable relative to the housing to select a clutch setting, and a contact assembly including a contact member and a spring non-removably coupled to the clutch selector with the spring biasing the contact member against the variable resistive element. The contact member has a head configured to engage the variable resistive element to generate a resistance signal that corresponds to a position of the clutch selector. The controller is configured to receive the resistance signal and, based on the resistance signal, look-up, receive, or generate a torque threshold value for an operation parameter of the system that corresponds to the selected clutch setting. In one embodiment, the head may include an asymmetrical shaped configuration. In one embodiment, the contact member may be a contact pin. In one embodiment, the head may include a projection disposed thereon, and the projection may be configured to engage the variable resistive element to generate the resistance signal that corresponds to the position of the clutch selector.

Another aspect of the present patent application provides a power tool. The power tool comprises a housing; an output spindle; an electric motor disposed in the housing and configured to provide torque to the output spindle; an input switch for actuating the electric motor; an electronic clutch; and a clutch setting assembly. The electronic clutch includes a sensor configured to sense a power tool operation parameter and a controller coupled to the sensor and configured to initiate a first protective operation to interrupt or reduce transmission of torque from the electric motor to the output spindle when the sensed power tool operation parameter indicates that an output torque has exceeded a torque threshold value. The clutch setting assembly includes a variable resistive element with a variable resistance coupled to the housing, a clutch selector movable relative to the housing to select a clutch setting, and a contact assembly coupled to the clutch selector, the contact assembly including a spring coupled to the clutch selector and a contact pin configured to be inserted into an opening in the clutch selector and then moved relative to the opening so that the contact pin is non-removable from the clutch selector and the spring biases the contact pin against the variable resistive element. The contact pin has a head configured to engage the variable resistive element to generate a resistance signal that corresponds to a position of the clutch selector. The controller is configured to receive the resistance signal and, based on the resistance signal, look-up, receive, or generate the torque threshold value for the power tool operation parameter that corresponds to the selected clutch setting.

Implementations of the foregoing aspects may include one or more of the following features. The contact pin may comprise a shaft including a key and the clutch selector may include a slot, whereby rotation of the contact pin causes the key to engage the slot to non-removably couple the contact pin to the clutch selector.

The clutch selector may include a spring keeper coupled to the spring. The contact pin may be moveable relative to the spring keeper to non-removably retain the spring, the spring keeper, and contact pin relative to the clutch selector.

Yet another aspect of the present patent application provides a power tool. The power tool comprises a housing, an output spindle, an electric motor, an input switch for actuating the electric motor, an electronic clutch, and a clutch setting assembly. The electric motor is disposed in the housing and is configured to provide torque to the output spindle. The electronic clutch includes a sensor configured to sense a power tool operation parameter and a controller. The controller is coupled to the sensor and is configured to initiate a first protective operation to interrupt or reduce transmission of torque from the electric motor to the output spindle when the sensed power tool operation parameter exceeds a torque threshold value. The clutch setting assembly includes a variable resistive element with a variable resistance coupled to the housing, a clutch selector movable relative to the housing to select a clutch setting, and a contact assembly non-removably coupled to the clutch selector. A portion of the contact assembly is configured to be axially biased along a longitudinal axis of the power tool and away from the clutch selector to engage the variable resistive element to generate a resistance signal that corresponds to a position of the clutch selector. The controller is configured to receive the resistance signal and, based on the resistance signal, look-up, receive, or generate the torque threshold value for the power tool operation parameter that corresponds to the selected clutch setting.

In one embodiment, the variable resistive element includes a plurality of conductive elements circumferentially spaced apart on the variable resistive element. In one embodiment, resistance of the variable resistive element changes when pressure is applied by the portion of the contact assembly on one of the plurality of conductive elements disposed along the variable resistive element.

In one embodiment, the contact assembly is configured to rotate along with the clutch selector. In one embodiment, the contact assembly includes a contact member and a spring configured to axially bias a portion of the contact member to engage the variable resistive element to generate the resistance signal that corresponds to the position of the clutch selector. In one embodiment, the portion of the contact assembly includes the portion of the contact member. In one embodiment, the contact member may be a contact pin. In one embodiment, the contact member may include an asymmetrical shaped plate portion and a projection disposed thereon, and the projection may be configured to engage the variable resistive element to generate the resistance signal that corresponds to the position of the clutch selector.

In one embodiment, the sensor includes a current sensor that is configured to sense an amount of current being delivered to the motor and to provide a current sensing signal corresponding to the sensed current to the controller.

In one embodiment, the sensor includes a rotation sensor that is configured to sense changes in an angular position of an output shaft of the motor and to provide a sensing signal corresponding to angular rotation, speed, and/or acceleration of the motor to the controller.

In one embodiment, the first protective operation includes at least one of interrupting power to the motor, reducing power to the motor, braking the motor, and actuating a mechanical clutch element.

DETAILED DESCRIPTION

In one embodiment, referring toFIGS.1A,1B,2,17and19, the present patent application provides a power tool10. The power tool10comprises a housing12, an output spindle13(as shown inFIG.19), an electric motor14, an input switch16for actuating the electric motor14, an electronic clutch40, and a clutch setting assembly200. The electric motor14is disposed in the housing12and is configured to provide torque to the output spindle13. The electronic clutch40includes one or more sensors48,50(as shown inFIG.1B) and a controller42(as shown inFIG.1B). The sensor(s)48,50of the electronic clutch40is/are configured to sense one or more power tool operation parameters. The controller42of the electronic clutch40is coupled to the sensor(s)48,50and is configured to initiate a first protective operation to interrupt or reduce transmission of torque from the electric motor14to the output spindle13when the sensed power tool operation parameter exceeds a torque threshold value. The clutch setting assembly200includes a variable resistive element202, a clutch selector27, and a contact assembly204. The variable resistive element202has a variable resistance and is coupled to the housing12. The contact assembly204is coupled to the clutch selector27. The clutch selector27is movable relative to the housing12to select a clutch setting.

The contact assembly204includes a spring208coupled to the clutch selector27and a contact member206with a shaft224configured to be insertable into an opening210in the clutch selector27so that the spring208and the contact member206are non-removable from the clutch selector27and the spring208biases the contact member206against the variable resistive element202. The contact member may interchangeably referred to as contact pin. The contact pin206has a head226configured to engage the variable resistive element202to generate a resistance signal that corresponds to a position of the clutch selector27. The controller42is configured to receive the resistance signal and, based on the resistance signal, is configured to look-up, receive, or generate the torque threshold value for the power tool operation parameter that corresponds to the selected clutch setting.

In one embodiment, the contact member206is configured to be snap-fit with the clutch selector27, so that the contact member206is non-reversibly non-removable from the clutch selector27and the spring208biases the contact member206against the variable resistive element202. In one embodiment, the contact member206includes the shaft224received in the opening210in the clutch selector27and a catch232coupled to the shaft224configured to engage an undercut222in the opening210.

In one embodiment, a portion (e.g., a portion of the contact pin206, a contact point230of the contact pin206, or the head226of the contact pin206) of the contact assembly204is configured to be axially biased along a longitudinal axis A-A (as shown inFIG.12) of the power tool10and away from the clutch selector27to engage the variable resistive element202to generate a resistance signal that corresponds to a position of the clutch selector27. The contact assembly204is configured to rotate along with the clutch selector. The contact assembly204includes the contact member206and the spring208configured to axially bias a portion (e.g., a portion of the contact pin206, a contact point230of the contact pin206, or the head226of the contact pin206) of the contact member206to engage the variable resistive element202to generate the resistance signal that corresponds to the position of the clutch selector27. In one embodiment, the portion of the contact assembly204includes the portion of the contact member206.

FIG.1Ashows an exemplary power tool10constructed in accordance with the teachings of the present patent application. As those skilled in the art will appreciate, embodiments may include either a corded or cordless (battery operated) power tool/device. The power tool may be a power screwdriver, a power fastener/fastening tool, a power driver, a power drill, a power expansion tool, and/or other power tools. In illustrated embodiment ofFIG.1A, the power tool10is a power (cordless) drill/screwdriver. The power tool10may be a portable device.

In one embodiment, the power tool10generally includes the housing12, the motor/motor assembly14, a multi-speed transmission assembly15, the electronic clutch/ electronic clutch assembly40, the output shaft/output spindle assembly13, a tool holder/chuck26, the input switch/trigger assembly16and a battery pack20. The output spindle13may be interchangeably referred to as output spindle assembly, output shaft or output member. Those skilled in the art will understand that several of the components of the power tool10, such as the tool holder26, the trigger assembly16and the battery pack20, are conventional in nature and therefore need not be discussed in significant detail in the present patent application. Reference may be made to a variety of patents/patent publications for a more complete understanding of the conventional features of the power tool10. One example of such patents is U.S. Pat. No. 5,897,454 issued Apr. 27, 1999, which is hereby incorporated by reference in the present patent application in its entirety.

Referring toFIG.1A, the housing12includes a pair of mating handle shells that cooperate to define a handle portion18and a drive train or body portion19. The body portion19may include a motor receiving portion and a transmission receiving portion. In one embodiment, the housing12is configured to be coupled to an electrical power source. The electrical power source may include the battery pack20or an AC power source as described in detail below.

In one embodiment, the output spindle13is proximate a front end of the housing12and is coupled/connected to the tool holder26for holding a power tool accessory, e.g., a tool bit. The output spindle13is configured to rotationally drive the tool holder26that is configured to receive the tool bit portion therein. The power tool accessory may include a tool bit such as a drill bit, an expansion bit, a screwdriver bit and/or other tool bits. The tool holder26may be a keyless chuck, although it should be understood that the tool holder can have other tool holder configurations such as a quick release tool holder, a hex tool holder, or a keyed tool holder/chuck. The tool holder26may be interchangeably referred to as an end effector, a chuck, etc. In one embodiment, the end effector26is coupled to the housing12and is configured to perform an operation on a workpiece (not shown).

In one embodiment, the input switch/trigger assembly16and the battery pack20are mechanically coupled to the handle portion18and are electrically coupled to the motor assembly14in a conventional manner that is not specifically shown but which is readily the capabilities of one having an ordinary level of skill in the art. The power tool10may include other sources of power (e.g., alternating current (AC) power cord or compressed air source) coupled to a distal end of the handle portion18.

The trigger assembly16may be a variable speed trigger. The trigger assembly16may be interchangeably referred to as an input switch. In one embodiment, the input switch16is configured for actuating the motor14. The trigger assembly16is configured to be coupled to the housing12for selectively actuating and controlling the speed of the motor14, for example, by controlling a pulse width modulation (PWM) signal delivered to the motor14.

In one embodiment, the motor14is disposed in the housing12and is configured to provide a torque to the output spindle13. The motor14may be a brushless or electronically commutated motor, although the motor14may be another type of brushed DC motor or universal motor.

The motor assembly14is housed in the motor receiving portion and includes a rotatable output motor shaft, which extends into the transmission receiving portion. In one embodiment, a motor pinion having a plurality of gear teeth is coupled for rotation with the rotatable output motor shaft. The trigger assembly16and battery pack29cooperate to selectively provide electric power to the motor assembly14so as to permit the user of the power tool10to control the speed and direction with which the rotatable output motor shaft rotates. The motor assembly14may interchangeably be referred to as motor14. In one embodiment, the motor output shaft extends from the motor14to the transmission15that transmits power from the motor output shaft to the output spindle13and to the tool holder26.

In one embodiment, the transmission assembly15comprises a multi-speed transmission having a plurality of gears and settings that allow the speed reduction through the transmission15to be changed, in a manner well understood to one of ordinary skill in the art. The transmission assembly15may comprise a multi-stage planetary gear set, with each stage having an input sun gear, a plurality of planet gears meshed with the sun gears and pinned to a rotatable planet carrier, and a ring gear meshed with and surrounding the planet gears. For each stage, if a ring gear is rotationally fixed relative to the housing12, the planet gears orbit the sun gear when the sun gear rotates, transferring power at a reduced speed to their planet carrier, thus causing a speed reduction through that stage. If a ring gear is allowed to rotate relative to the housing12, then the sun gear causes the planet carrier to rotate at the same speed as the sun gear, causing no speed reduction through that stage. By varying which one or ones of the stages have the ring gears are fixed against rotation, one can control the total amount of speed reduction through the transmission15, and thus adjust the speed setting of the transmission15(e.g., among high, medium, and low). In one embodiment, this adjustment of the speed setting is achieved via a shift ring that surrounds the ring gears and that is shiftable along the axis of the output spindle13to lock different stages of the ring gears against rotation. In one embodiment, the power tool10includes a speed selector switch29for selecting the speed reduction setting of the transmission15. In one embodiment, the speed selector switch29is coupled to the shift ring by spring biased pins so that axial movement of the speed selector switch29causes the axial movement of the shift ring. Further details regarding an exemplary multi-speed transmission is described in U.S. Pat. No. 7,452,304 which is incorporated by reference in the present patent application in its entirety. It should be understood that other types of multi-speed transmissions and other mechanisms for shifting the transmission among the speeds is within the scope of the present patent application.

In one embodiment, the power tool10includes the controller/control circuit42. The controller may be interchangeably referred to as a control circuit. The controller42is disposed in the housing12and is operatively cooperable with the motor14. As will be clear from the detailed discussions below, the controller42is also operatively coupled to other components of the power tool10(including sensors,48,50,56,58, and/or memory45). The controller42is configured to receive sensed power tool operation parameters and other setting parameters from the sensors and configured to initiate a first protective operation to interrupt or reduce transmission of torque from the electric motor14to the output spindle13when the sensed power tool operation parameter exceeds a torque threshold value.

In one embodiment, the controller42is referred to as a microcontroller. In another embodiment, the controller42is referred to, be part of, or includes an electronic circuit, an Application Specific Integrated Circuit (ASIC), a processor (shared, dedicated, or group) and/or memory (shared, dedicated, or group) that execute one or more software or firmware programs, a combinational logic circuit, and/or other suitable components that provide the described functionality.

In one embodiment, the electronic clutch/electronic clutch assembly40is disposed in the housing12. The electronic clutch assembly40is disposed in the housing12between the motor14and the end effector26.

In one embodiment, the controller42for the electronic clutch40needs to know the position of the rotatable clutch collar27(i.e., configured for selecting the clutch setting) in order to adjust the clutch setting. As will be clear from the detailed discussions in the present patent application, the clutch setting/the position of the rotatable clutch collar27is sensed using the sensor/stationary membrane potentiometer/variable resistive element202. The contact assembly204of the clutch setting assembly200is non-removably coupled to and rotates along with the clutch collar27.

In one embodiment, the potentiometer contact point230of the contact assembly204is configured to be pressed against the membrane potentiometer/variable resistive element202. Depending on the rotational position of the clutch collar27and the contact assembly204non-removably coupled to the clutch collar27, the potentiometer contact point230of the contact assembly204engages with a different location/portion of the stationary membrane potentiometer/variable resistive element202. Thus, the resistance in the variable resistive element202would change and the controller42for the electronic clutch40could sense the rotational position of the clutch collar27.

In illustrated embodiment, as shown inFIG.1B, the electronic clutch assembly40includes the controller42and the sensor(s)48,50.

In one embodiment, the sensor(s)48,50is/are configured to sense one or more power tool operation parameters.

In one embodiment, the electronic clutch assembly40includes one sensor48, for example, the current sensor48that is configured to sense an amount of current being delivered to the electric motor14. For example, in this embodiment, the power tool operation parameter includes the amount of current being delivered to the electric motor14.

In another embodiment, the electronic clutch40includes two sensors48,50, where one sensor48is the current sensor48that is configured to sense an amount of current being delivered to the electric motor14and the other sensor50is a position/rotation sensor50that is configured to sense the changes in an angular position of the motor output shaft and that provides a signal corresponding to angular rotation, speed, and/or acceleration of the electric motor14to the controller42of the electronic clutch40. For example, in this embodiment, the power tool operation parameters include the amount of current being delivered to the electric motor14, the rotational speed of the electric motor14, the rotation of the electric motor14, the speed of the electric motor14, and the acceleration of the electric motor14.

The number of sensors in the electronic clutch40may vary. The sensors48,50of the electronic clutch40are operatively coupled/connected to the electric motor14to sense the power tool operation parameters and are operatively coupled/connected to the controller42. The sensors48,50of the electronic clutch40are configured to send the sensed power tool operation parameters to the controller42.

In illustrated embodiment, as shown inFIG.1B, the electronic clutch assembly40includes the controller42, a current sensing circuit44, and a position sensing circuit46. The current sensing circuit44includes the current sensor48(e.g., a shunt resistor) that senses the amount of current being delivered to the motor14and provides a current sensing signal corresponding to the sensed current to the controller42. The position/rotation sensing circuit46includes one or more position/rotation sensors50that sense changes in an angular position of the motor output shaft and provides a signal corresponding to angular rotation, speed, and/or acceleration of the motor14to the controller42.

In one embodiment, the position sensors are Hall sensors that are already part of a brushless motor. For example, the power tool10may include a three-phase brushless motor, where the rotor includes a four-pole magnet, and there are three Hall sensors positioned at 120° intervals around the circumference of the rotor. As the rotor rotates, each Hall sensor senses when one of the poles of the four-pole magnet passes over the Hall sensor. Thus, the Hall sensors can sense each time the rotor, and thus the motor output shaft, rotates by an increment of 60°.

In one embodiment, the rotation sensing circuit can use the signals from the Hall sensors to infer or calculate the amount of angular rotation, speed, and/or acceleration of the rotor. For example, the rotation sensing circuit includes a clock or counter that counts the amount of time or the number of counts between each 60° rotation of the rotor. The controller42is configured to use this information to calculate or infer the amount of angular rotation, speed, and/or acceleration of the motor14.

In one embodiment, the power tool operation parameters generally include an amount of current being delivered to the electric motor14, rotational speed of the electric motor14, rotation of the electric motor14, speed of the electric motor14, acceleration of the electric motor14, etc.

In one embodiment, as shown inFIG.1B, the controller42of the electronic clutch40is coupled to the sensors48,50and is configured to receive the power tool operation parameters from the sensors48,50of the electronic clutch40. The controller42of the electronic clutch40is configured to initiate a first protective operation to interrupt or reduce transmission of torque from the electric motor14to the output spindle13when the sensed power tool operation parameter exceeds a torque threshold value. That is, when conditions (the sensed power tool operation parameter exceeds the torque threshold value) triggering the first protective operation have been met, the controller42of the electronic clutch40is configured to interrupt or reduce torque transmission to the output spindle13.

In one embodiment, the controller42of the electronic clutch40is configured to initiate the first protective operation when the sensed current signal exceeds a current threshold value In another embodiment, the controller42of the electronic clutch40is configured to initiate the first protective operation when the sensed rotation/position signal indicates that the rotational speed of the electric motor14is decreasing and the sensed current signal exceeds a first current threshold value. In another embodiment, the controller42of the electronic clutch40is configured to initiate the first protective operation only if the controller42of the electronic clutch40has previously determined that the sensed current signal exceeds a second current threshold value that is different than the first current threshold value.

In one embodiment, the first protective operation interrupts torque transmission to the output spindle13e.g., by interrupting power to the electric motor14, reducing power to the electric motor14, and/or actively braking the electric motor14(e.g., by shorting across the windings of the electric motor14). The first protective operation comprises actuating a mechanical clutch element.

In one embodiment, a soft braking scheme is employed as the first protective operation. When conditions triggering the protective operation have been met, power to the electric motor14is cut off and the electric motor14is permitted to coast for a predefined period of time (e.g., 10-30 milliseconds). The PWM signal is then reapplied to the electric motor14. The PWM signal is initially applied at a 100% duty cycle to the electric motor14and then gradually decreased to a much lower duty cycle (e.g., 3%). The PWM signal continues to be applied to the electric motor14for a period of time before being set of zero (i.e., interrupting power to the electric motor14). It is envisioned that the PWM signal applied to the electric motor14during braking may be decreased linearly, exponentially, or in accordance with some other function from 100%. In other embodiments, the PWM signal may also be ramped up linearly, exponentially or in accordance with some other function from zero to 100%. Other variants for the soft braking of the motor are also contemplated by this disclosure. Moreover, in other embodiments, other types of protective operations fall with the scope of this disclosure.

In one embodiment, the controller42is also configured to initiate a second protective operation to interrupt or reduce transmission of torque to the output spindle13when the controller determines that the input switch16has been actuated a second time within a predetermined time after the first protective operation to continue driving a fastener after the first protective operation and the sensed current signal exceeds a second current threshold value that is less than the first current threshold value.

In one embodiment, the controller42of the electronic clutch40is configured to receive an input indicative of a clutch setting from the clutch selector27and to determine the torque threshold valve in accordance with the selected clutch setting.

The threshold values can be varied depending on one or more of the clutch setting, the selected speed of the transmission, and the duty cycle of the PWM signal (which corresponds to the amount of trigger travel). In illustrated embodiment, as shown inFIG.1B, the electronic clutch40includes a memory45operatively coupled to the controller42. The memory45may include a look-up table that correlates combinations of values for the clutch setting, the speed setting, and the PWM duty cycle, to the threshold values. The controller42is configured to use the look-up table to select one or more of the threshold values based upon the selected clutch setting, the selected speed setting, and the amount of trigger travel or PWM duty cycle. For example, in one embodiment, for clutch setting 1, speed setting 1, and a PWM duty cycle of 75-100% of maximum, there will first (set of) threshold values. In another embodiment, for clutch setting 3, speed setting 2, and a PWM duty cycle of 25-50% of maximum, there will be the second (set of) threshold values. In general, the threshold values increases with an increase in motor speed (caused by either an increase in duty cycle or a change in gear setting) as well as with an increase in the desired clutch setting. It should be understood that the threshold values in the look-up table may be derived empirically and will vary based on many factors such as the type of power tool, the size of the motor, the voltage of the battery, etc. In addition, it should be understood that the look-up table can include fewer parameters used to determine the threshold values (e.g., only clutch setting, but not speed setting or PWM duty)).

In one embodiment, the threshold values include a threshold value for the maximum angular position of the rotor, a threshold value for the minimum angular position of the rotor, a threshold value for the current when the fastener should be seated, a threshold value for the minimum current drawn by the motor14, a threshold value for the maximum current drawn by the motor14, etc. It should be understood that the look-up table can include only some of the above-discussed threshold values. It should be understood that the look-up table can include other types of threshold values that are not disclosed here but are obvious to a person of ordinary skill in the art. In addition, the look-up table may be divided into multiple look-up tables for different modes of operation.

In one embodiment, the clutch setting assembly200includes the variable resistive element202with a variable resistance fixedly coupled to the housing12, the clutch selector27movable relative to the housing12to select a clutch setting, and the contact assembly204. The contact assembly204of the clutch setting assembly200includes the contact pin206and the spring208that are non-removably coupled to the clutch selector27with the spring208biasing the contact pin206against the variable resistive element202. The variable resistive element202is non-movable relative to the housing12.

In one embodiment, the electronic clutch40includes a clutch setting circuit52. The clutch setting circuit52includes a clutch setting sensor56that senses the setting set of the clutch selector/setting collar27and that provides a signal corresponding to that clutch setting to the controller42. The clutch selector27comprises the collar rotatably coupled to the housing12and rotation of the collar27changes the selected clutch setting. The clutch selector27may be interchangeably referred to as the clutch collar27. In illustrated embodiment, as illustrated in and described in detail below with respect toFIGS.2-17, the clutch collar27is part of the clutch setting assembly200and is operatively coupled to the contact assembly204and the variable resistive element202(that are both part of the clutch setting assembly200). The clutch setting sensor56may be in the form of the variable resistive element202. The contact assembly204is affixed to the clutch collar27so that the contact assembly204rotates together with the clutch collar27, while the variable resistive element202remains stationary. The spring208of the contact assembly204is configured to bias the contact pin206against the variable resistive element202. The contact pin206of the contact assembly204has the head226that is configured to engage the variable resistive element202to generate a resistance signal that corresponds to a position of clutch setting collar27. As the head226of the contact pin206moves along the variable resistive element202, the resistance changes. Thus, by sensing the voltage at the output of the variable resistive element202, the clutch setting circuit52can sense the position or clutch setting of the clutch collar27. In other embodiments, the clutch collar27may be coupled to another type of potentiometer or variable resistor, to another type of sensor such as one or more Hall effect sensors, or using a switch, or to another type of switch such as a multi-pole switch, to sense position of the clutch collar27.

The clutch setting circuit52includes the clutch setting assembly200. The clutch setting switch/collar27is actuatable to select a clutch setting. The clutch setting circuit52/the clutch setting assembly200is configured to generate a clutch setting signal that corresponds to the clutch setting. The clutch setting signal causes the controller42to adjust the threshold torque value in relationship to the clutch setting.

The clutch setting switch27includes a setting for a drill mode. When the clutch setting signal indicates that the clutch setting switch27is in the drill mode, the controller42deactivates the electronic clutch40. The clutch setting switch27may include one or more settings for no-hub modes. When the clutch setting signal indicates that one or more of the no-hub modes has been selected, the controller42may limit the PWM duty cycle to be less than a maximum duty cycle (e.g., approximately 50% of the maximum duty cycle).

Referring toFIG.1B, the electronic clutch assembly40also includes a speed selector circuit54that senses the position of the speed selector switch29to determine which speed setting has been selected by the user. The speed selector switch29is actuatable to select an output speed of the output spindle13. The speed selector circuit54is configured to generate a speed selector signal that corresponds to a position of the speed selector switch29. The speed selector signal causes the controller42to adjust the threshold torque value in relationship to the speed setting.

In one embodiment, the speed selector switch29is coupled to a member (e.g., pin) that is biased downwardly by a spring against a speed setting sensor58in the form of a linear variable resistive element (membrane potentiometer). The member and spring move linearly with the speed selector switch29, while the linear variable resistive element remains stationary, such that the resistance of the linear variable resistive element changes with different speed settings. Thus, by sensing the voltage drop across the linear variable resistive element, the speed selector circuit54can sense the position or speed setting of the speed selector switch29, and provides a signal corresponding to the speed setting to the controller42. In other embodiments, the speed selector switch29may be coupled to another type of potentiometer or variable resistor, to another type of sensor such as one or more Hall effect sensors, or to another type of switch, such as a multi-pole switch, to sense position of the speed selector switch29.

In one embodiment, the operation and the configuration of the controller, the sensors (position and/or current), the memory, and/or the transmission speed sensor shown inFIG.1Bof the present patent application are similar to the corresponding controller, sensors (position and/or current), memory, and/or transmission speed sensor described in detail in the ‘500 Patent, which is incorporated by reference in its entirety.

In one embodiment, the clutch setting sensor56(as shown inFIG.1B) is in the form of the variable resistive element202. The variable resistive element202is configured to be fixedly coupled to the housing12. The variable resistive element202is shown inFIGS.17-19.

In one embodiment, the variable resistive element202includes a membrane potentiometer. The variable resistive element202has a variable resistance. The variable resistive element202comprises a flat, semi-conductive strip or membrane whose resistance changes when pressure is applied in different locations along the membrane.

FIGS.18-19show the clutch setting assembly200from the back/rear side thereof. That is,FIGS.18-19show back side of the electronic clutch printed circuit board (PCB). In one embodiment, the variable resistive element202includes a plurality of conductive elements250circumferentially spaced apart on the variable resistive element202. Resistance of the variable resistive element changes when pressure is applied by the portion (e.g., contact point230) of the contact assembly204on one of the plurality of conductive elements250disposed along the variable resistive element202.FIGS.18-19also show the radial placement of the multiple resistors or conductive elements250on the variable resistive element202. In one embodiment, the membrane is composed of a variety of materials, such as PET, foil, FR4, and/or Kapton. The variable resistive element202may be in the form of an annular ring or a semi annular ring. The variable resistive element202may be in the form of a semi-circle or a full circle.

In one embodiment, the variable resistive element202is configured such that as the head226of the contact pin206moves along the variable resistive element202and the potentiometer contact point230of the head226engages different portions/locations of the variable resistive element202, the resistance changes. Thus, by sensing the voltage at the output of the variable resistive element202, the clutch setting circuit52can sense the position or clutch setting of the clutch collar27.

In one embodiment, the power tool10includes the clutch setting switch or collar27that is used to adjust a clutch setting of the electronic clutch40. The user is able to control the amount of slip, e.g., via the clutch setting collar27. The clutch selector27is configured to receive a user selection of a clutch setting. The user rotates the clutch collar27among a plurality of different positions for different maximum torque settings. The clutch setting collar27may be interchangeably referred to as clutch setting input device, clutch setting switch, clutch collar, clutch selector or rotatable clutch collar. The electronic clutch40may include the rotatable clutch collar27for selecting the clutch setting.

In one embodiment, the clutch selector27is disposed on the housing12. The clutch collar27is attached to the power tool10between the tool and the tool holder or chuck26. The clutch selector27is configured to be movable relative to the housing12of the power tool10to select a clutch setting. The clutch selector27is configured to be rotatable relative to the housing12of the power tool10to select a clutch setting.

In one embodiment, as shown inFIGS.3-5, the clutch collar27has a contact pin receiving portion/keyhole slot210that receives the contact pin206and that is flanked by a pair of spring receiving portions/spring pockets214that receive the springs208. The contact pin receiving portion/keyhole slot210may interchangeably referred to as the opening210of the clutch collar27. The shaft224of the contact member206is configured to be insertable into the opening210of the clutch collar27. The spring208of the spring keeper236is received within the opening214of the clutch selector27and the leg240of the spring keeper236is received within the spring208. A second spring208is received in a second (spring) opening214in the clutch selector27. From the insertion side, as shown inFIG.4, the keyhole slot210includes a round center portion216and a radial extension218facing one of the spring pockets214. From the opposite retaining side, as shown inFIG.5, the keyhole slot210has the round center portion216, the radial extension218, an arc shaped recess220, and a retaining groove222. The retaining groove222is disposed at an angle of 90° to the radial extension218.

In the ‘500 Patent, the spring with the stylus-type projection (as shown inFIG.7of the ‘500 Patent) is configured to be pressed against the membrane potentiometer to enable the rotational position of the clutch collar to be sensed. Applicant of the present patent application has found that, however, often the spring70of the ‘500 Patent may fail over time, yielding inaccurate clutch setting signals.

Applicant of the present patent application has, therefore, developed the contact assembly204in the present patent application. Referring toFIGS.2-7, the contact assembly204includes the contact pin206, a spring keeper236, and a pair of compression springs208all received in and retained by the clutch selector27. The contact assembly204, including the contact pin206, the spring keeper236, and the springs208received in the clutch selector27, is configured to provide a more robust contact assembly, while also having a design that provides for ease of assembly by allowing the contact pin206to be retained in the clutch collar27in a manner so that contact pin206can be held upside down without the contact pin206falling out. The spring keeper236is coupled to the spring208. The contact pin206coupled to the spring keeper236. The contact pin206is moveable relative to the spring keeper236to non-removably retain the spring208, the spring keeper236, and contact pin206relative to the clutch selector27.

The contact assembly204may interchangeably be referred to as contact pin assembly. The contact assembly204includes the contact member/pin206and the spring208that are non-removably coupled to the clutch selector27such that the contact assembly204rotates along with the clutch selector27.

In illustrated embodiment, as shown inFIG.6, the contact pin206includes the shaft224and the head226at one end228of the shaft224. The head226of the contact pin206is asymmetrical. The head226of the contact pin206includes the contact point230. The contact point230is configured to engage with portions of the variable resistive element202when the springs208of the contact assembly204bias the contact pin206against variable resistive element202. The contact point230may be interchangeably referred to potentiometer contact point. The contact point230is configured to extend/protrude, along the longitudinal axis CPL-CPLof the contact pin206, outwardly and away from the surface256of the asymmetric head226.

In illustrated embodiment, as shown inFIG.6, the contact pin206also includes a catch232at an opposite end234of the shaft224. The catch232is configured to extend/protrude, along the first transverse axis CPT1-CPT1of the contact pin206, outwardly and away from the external surface258of the shaft224of the contact pin206. The catch232of the contact pin206may interchangeably referred to as key232. That is, the contact pin206includes the shaft224that includes the key232.

In one embodiment, the head226of the contact pin206is asymmetric about the longitudinal axis CPL-CPLof the contact pin206and the second transverse axis CPT2-CPT2of the contact pin206. In another embodiment, the head226of the contact pin206is symmetric about the first transverse axis CPT1-CPT1of the contact pin206.

In one embodiment, the asymmetrical shaped configuration of the head226of the contact pin206and the outwardly extending/protruding contact point230of the contact pin206are configured to enable the engagement of the head226/the contact point230of the contact pin206with the variable resistive element202, when the contact pin206is biased by the springs208, so as to generate the resistance signal that corresponds to the position of the clutch selector27.

As will be clear from the detailed discussions below, the catch232of the contact pin206is configured to engage with portions of the clutch selector27so as to non-removably couple the contact assembly204(including the contact pin206and the springs208) to the clutch selector27.

In one embodiment, the contact pin206may be made of a material that is configured to withstand the vibrations and/or other forces in the power tool10. In one embodiment, the contact pin206is made of impact resistance material or impact absorbing material.

In one embodiment, the contact assembly204includes the pair of springs208that is received in and is non-removably coupled to the clutch collar27. The springs208are compression springs. The pair of compression springs208is received in the spring pockets214of the clutch collar27and is configured to receive a pair of lateral legs240of a spring keeper236therein. The diameter of each of the pair of compression springs208is sized to fit into the corresponding spring pockets214of the clutch collar27and also sized to receive the corresponding one of the pair of lateral legs240of the spring keeper236in the assembled configuration of the contact assembly204. The pair of compression springs208is positioned symmetrically on both sides of the contact pin206.

In one embodiment, the pair of the springs208of the contact assembly204is configured to bias the contact pin206against the variable resistive element202. The two compression springs208are configured to work together to produce a minimum force of approximately 11 Newton (N). In another embodiment, the minimum force produced by the spring208is up to 5, 10, 15 or 20 percent greater than or up to 5, 10, 15 or 20 percent less than the value described above.

In one embodiment, the springs208may be made of a material that is configured to withstand the vibrations and/or other forces in the power tool10. In one embodiment, the springs208are made of impact resistance material or impact absorbing material.

In illustrated embodiment, referring toFIG.7, the contact assembly204includes the spring keeper236. The spring keeper236has a top plate/member238, the pair of lateral legs240extending downward from the top plate/member238, a recess242configured for receiving the head226of the contact pin206, and a keyhole slot248configured for receiving portions of the contact pin206therethrough.

In one embodiment, the diameter of each of the pair of lateral legs240is sized to fit into the corresponding springs208in the assembled configuration of the contact assembly204. When the contact assembly204is assembled and is non-removably coupled to the clutch collar27, the pair of lateral legs240are aligned and received in the compression springs208.

In one embodiment, the recess242includes the same shaped configuration as the head226of the contact pin206such that the recess242acts as an alignment feature for the contact pin206in the assembled configuration of the contact assembly204.

In one embodiment, the spring keeper236includes a protrusion portion262that is disposed centrally (along the longitudinal axis SK-SK) in the top plate/member238and extending outwardly from the top plate/member238. The protrusion portion262of the spring keeper236is configured to act as an alignment feature for the spring keeper236when the spring keeper236is pressed down to be flush with the clutch collar27so as to rotate the contact pin206and to align the catch232of the contact pin206with the retaining groove222in the clutch collar27. The retaining groove222in the clutch collar27may interchangeably referred to as slot222or the undercut in the opening210. That is, the clutch selector27includes the slot/retaining groove222, whereby rotation of the contact pin206causes the key/catch232to engage the slot/retaining groove222to non-removably couple the contact pin206to the clutch selector27.

In one embodiment, the protrusion portion262of the spring keeper236is configured to align with and inserted into receiver portion264(as shown inFIG.13) of the clutch collar27when the spring keeper236is pressed down to be flush with the clutch collar27so as to rotate the contact pin206and to align the catch232of the contact pin206with the retaining groove222in the clutch collar27.

In one embodiment, the recess242and the keyhole slot248are positioned between the pair of lateral legs240along the longitudinal direction SK-SK of the spring keeper236. The keyhole slot248of the spring keeper236includes a round center portion244and a radial extension246(e.g.,FIG.12). The keyhole slot248of the spring keeper236includes the same shaped configuration as the keyhole slot210in the clutch collar27such the round center portions and radial extensions of the keyhole slot248of the spring keeper236and the keyhole slot210in the clutch collar27align with each other to receive portions of the contact pin206therein.

The spring keeper236may be made of a material that is configured to withstand the vibrations in the power tool10. The spring keeper236is made of impact resistant material or impact absorbing material. The spring keeper236may also interchangeably referred to contact assembly housing/receiving member.

In one embodiment, the spring keeper236includes a cutout portion252at one end254of the top plate/member238to remove excess material of the spring keeper236. In another embodiment, the cutout portion252is optional.

FIGS.9-16show various procedures in a method of assembling the contact assembly204of the clutch setting assembly200and non-removably coupling the contact assembly204of the clutch setting assembly200to the clutch selector27according to an embodiment of the present patent application.

FIGS.9and10show the clutch selector27before and after the springs208being inserted/received therein, respectively. In one embodiment, the springs208of the contact assembly204are inserted into the spring pockets214in the clutch selector/collar27.

FIGS.11and12show the clutch selector27before and after the spring keeper236being inserted therein, respectively. In one embodiment, the legs240of the spring keeper236are inserted into the openings260of the springs208, which are inserted in the spring pockets214in the clutch selector/collar27. After the spring keeper236is inserted into the clutch selector27as shown inFIG.12, the keyhole slot210in the clutch selector/collar27is aligned with the keyhole slot248in the spring keeper236. After the spring keeper236is inserted into the clutch selector27as shown inFIG.12, the round center portion216and the radial extension218of the keyhole slot210in the clutch selector/collar27are aligned with the round center portion244and the radial extension246of the keyhole slot248in the spring keeper236.

FIGS.12and13show the clutch selector27before and after the contact pin206being inserted therein, respectively. In one embodiment, the catch232of the contact pin206is aligned with and inserted into the radial extension218of the keyhole slot210in the clutch selector/collar27and the radial extension246of the keyhole slot248in the spring keeper236as the contact pin206is inserted through the keyhole slot248in the spring keeper236and the keyhole slot210in the clutch selector/collar27.

FIG.13also shows the contact pin206and the spring keeper236pressed down to be flush with the clutch selector27so as to rotate the contact pin206to align the catch232of the contact pin206with the retaining groove222(as shown inFIG.5) of the clutch selector27. The contact pin206and the spring keeper236are pressed downwardly in the direction D toward the clutch selector/collar27and against the force of the springs208. The protrusion portion262of the spring keeper236aligns with and inserted into receiver portion264of the clutch collar27when the contact assembly204(including the contact pin206, the spring keeper236, and the springs208) is pressed down to be flush with the clutch collar27. The contact pin head226is then rotated, in the direction CR, by an angle of 90° to align the catch232of the contact pin206with the retaining groove222(as shown inFIG.5) in the underside of the clutch selector/collar27.

FIGS.14and16show the catch232of the contact pin206of the contact assembly204before and after being retained by the retaining groove222of the clutch selector27, respectively.FIG.15shows the contact assembly204including the contact pin206and the spring keeper236in its released and retained position.

Once the catch232of the contact pin206is aligned with and received in the retaining groove222in the underside of the clutch selector/collar27, the contact assembly204(including the contact pin206, the springs208and the spring keeper236) is released (upwardly in the direction U). The catch232of the contact pin206now abuts against (the top of) the retaining groove222of the clutch selector27, which retains the contact assembly204(including the contact pin206, the springs208and the spring keeper236) in the clutch selector/collar27(e.g., seeFIG.16). The catch232of the contact pin206interfaces with the retaining groove222of the clutch27and keeps the contact assembly204(including the contact pin206, the springs208and the spring keeper236) retained in the clutch selector/collar27. The recess242of the spring keeper236acts as an alignment feature for the contact pin206in the assembled configuration of the contact assembly204.

In one embodiment, the clutch selector/collar27is then assembled to the power drill housing12, so that the contact point230on the head226of the contact pin206engages or makes contact with the variable resistive element/membrane potentiometer202in the power drill housing12(e.g., seeFIG.17).

FIG.17shows the clutch setting assembly200including the contact assembly204(including the contact pin206, the springs208and the spring keeper236), the clutch selector27, and the variable resistive element202.FIG.17shows the contact point230on the head226of the contact pin206making contact with the potentiometer/variable resistive element202for the electronic clutch40. In one embodiment, the springs208bias the contact pin assembly204toward the variable resistive element/membrane potentiometer202to keep good contact between the contact point230of the contact pin head226and the variable resistive element/membrane potentiometer202.

In one embodiment, as the clutch collar27rotates to change the clutch setting, the head226of the contact pin206moves along with the clutch collar27to engage the contact point230on the head226of the contact pin206at a different location of the variable resistive element/membrane potentiometer202. This engagement changes the resistance of the variable resistive element/membrane potentiometer202, allowing the controller42for the electronic clutch40to sense the position of the clutch collar27.

In one embodiment, when the contact assembly204is in its assembled configuration, the bottom portions of the springs208are received in/engaged with portions of the clutch selector27and the top portions of the springs208are configured to engage with bottom surfaces of the top plate/member238of the spring keeper236and to exert an axial (i.e., away from the clutch selector27) force on the top plate/member238of the spring keeper236so as to bias the spring keeper236upwardly, along an axial/longitudinal axis A-A (as shown inFIG.12). In one embodiment, the axial (i.e., away from the clutch selector27) force is exerted by the springs208on the spring keeper236and also on the contact pin206received in the spring keeper236. In one embodiment, the axial/longitudinal axis A-A is an axis parallel to the longitudinal axis of the contact pin CPL-CPL.

As described in detail throughout the present patent application, in one embodiment, the axial (i.e., away from the clutch selector27) force is exerted by the springs208on the contact pin206received in the spring keeper236causes the contact point230of the contact pin206to engage with the variable resistive element202. As the contact assembly204rotates along with the clutch selector27, the contact pin206is configured to engage with different portions of the variable resistive element202. The engagement between the variable resistive element202and the contact pin206causes a resistance signal that corresponds to a position of the clutch selector27. The controller42is configured to receive this resistance signal and, based on the resistance signal, is configured to look-up, receive, or generate the torque threshold value for the power tool operation parameter that corresponds to the selected clutch setting.

In one embodiment, the potentiometer contact point230of the pin206is positioned at a radially inwardly portion (i.e., away from the clutch selector27) on the head226so as to engage with the variable resistive element202.

In one embodiment, the asymmetrical shaped configuration of the head226of the contact pin206and the outwardly extending/protruding contact point230of the contact pin206are configured to enable the engagement of the head226/the contact point230of the contact pin206with the variable resistive element202, when the contact pin206is biased by the springs208, so as to generate the resistance signal that corresponds to the position of the clutch selector27.

In one embodiment, the contact pin206and the springs208are two different structural members. The contact assembly204(including the contact pin206and the springs208) is a two-part configuration. The two-part spring loaded configuration includes pin with spring inside it.

Each compression spring208of the present patent application undergoes an axial movement (in the axial direction with respect to the longitudinal direction of the pin shaft) to exert an axial/longitudinal bias on the contact pin206and its potentiometer contact point230. The axial bias of springs208impart axial movement of the contact point against the potentiometer/variable resistive element202.

In one embodiment, the electronic clutch assembly40includes a plurality of clutch settings. Each clutch setting corresponds to a desired output operation of the power tool10. That is, the clutch setting of the electrostatic clutch40can be set by the user based on a desired output operation. For example, the desired output operation can include an amount of material to be removed from a workpiece (not shown). Each clutch setting has the set or predetermined torque. Each clutch setting is associated with a different clutch disengage torque (i.e., a torque at which the electronic clutch assembly40disengages to thereby prevent the transmission of torque transmission between the motor14and the output shaft13). Each predetermined clutch setting includes a maximum clutch setting, a minimum clutch setting, and a plurality of intermediate clutch settings between the maximum and minimum clutch settings.

In one embodiment, the power tool/drill/driver10is configured to provide a user perceptible output that indicates the occurrence of the protective operation. In one example embodiment, the user is provided with haptic feedback to indicate the occurrence of the protective operation. By driving the motor14back and forth quickly between clockwise and counterclockwise, the motor14can be used to generate a vibration of the housing that 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 motor to rotate. In the case of a conventional H-bridge motor drive circuit, the field effect transistors in the bridge circuit are selectively open and closed to change the current flow direction and therefore the rotational direction of the motor14.

In another example embodiment, the haptic feedback is generated using a different type of pulsing scheme. Rather than waiting to reach the maximum threshold value, the control algorithm can begin providing haptic feedback prior to reaching the maximum threshold value. The feedback is triggered when the torque (as indicated for example by the monitored current) reaches a trip current that is set at a value lower than the maximum threshold current. The value of the trip current may be defined as a function of the trigger position, transmission speed and/or clutch setting in a manner similar to the other threshold values.

In one embodiment, as shown inFIGS.20A-D, the spring loaded pin arrangement/contact assembly204includes other spring loaded pin configurations including through hole spring loaded pin arrangement (as shown inFIG.20A), surface mount spring loaded pin arrangement (as shown inFIG.20B), barrel crimp spring loaded pin arrangement (as shown inFIG.20C), solder cup spring loaded pin arrangement (as shown inFIG.20D) and/or other spring loaded pin arrangements that are appreciated by a person of ordinary skill in the art. Each of these spring loaded pin arrangements are shown inFIGS.20A-D. As would be appreciated by a person of ordinary skill in the art, each of the spring loaded pin arrangements include a housing for the pin, a pin, and one or more springs.

In one embodiment, the spring loaded pin arrangement/contact assembly204is configured to be insert molded into the clutch collar27. This provides for easy assembly for production, and eliminates blind assembly.

In one embodiment,FIGS.21A-Cshows various internal designs of the spring loaded pins in the spring loaded pin arrangements/contact assembly204including back drill design/configuration (as shown inFIG.21A), bias tail design/configuration (as shown inFIG.21B), ball design/configuration (as shown inFIG.21C), and/or other designs/configurations that are appreciated by a person of ordinary skill in the art. In the bias tail design/configuration, the bias406of the tail408of the pin410(at the contacting areas between the pin410and the spring412) creates a lateral force and better/improved contact. In the back drill design/configuration, the drilled tail414of the pin410creates extra space for the spring412and creates a shorter spring loaded pin. In the ball design/configuration, a ball416is configured to stabilize the contacting areas between the pin410and the spring412for better/improved performance.

FIG.22discloses another embodiment of the contact assembly304. The contact assembly304generally includes a contact pin306and springs316. The contact pin306includes an upside-down U-shaped configuration. The contact pin306include a cross-bar/head portion314and two legs308protruding downwardly from the cross-bar/head portion314. The head portion314may be interchangeably referred to as head314. Each leg308of the contact pin306has an outwardly protruding tangs/portions310on their end portions312. The head portion314has a projection318disposed thereon and extending upwardly away from the surface of the head portion314. The projection318is configured to engage with portions of the resistor PCB/variable resistive element (not shown in this figure but described in detail throughout the present patent application) to generate the resistance signal that corresponds to the position of the clutch selector. The legs308are configured to be squeezed together to insert the contact pin306into a bore/an opening320of a clutch selector/collar322. One or more compression springs316are configured to bias the contact pin306outwardly away from the bore/opening320of the clutch selector/collar322.

FIGS.23-34show another embodiment of the clutch setting assembly1200. The clutch setting assembly1200may include the variable resistive element1202(as shown inFIG.34) with a variable resistance (fixedly) coupled to the housing12, the clutch selector1027movable relative to the housing12to select a clutch setting, and the contact assembly1204. The contact assembly1204of the clutch setting assembly1200includes a contact member1206and a spring1208that are non-removably coupled to the clutch selector1027with the spring1208biasing the contact member1206against the variable resistive element1202. The configuration and the operation of the variable resistive element1202, the contact assembly1204, and the clutch selector1027are similar to that of the variable resistive element202, the contact assembly204, and the clutch selector27except for the differences described in detail below.

The contact assembly1204includes the contact member1206and the spring1208that are non-removably coupled to the clutch selector1027such that the contact assembly1204rotates along with the clutch selector1027. In the illustrated embodiment ofFIGS.27-34, the design of the contact assembly1204eliminates a separate contact pin (206in the discussions above) and combines/integrates the contact pin/member head geometry1206into the spring keeper1236itself. Thus, this embodiment ofFIGS.27-34eliminates a separate part and making the assembly procedures even easier. Also, the spring keeper1236includes a snap tab design that snaps into corresponding features into the clutch collar1027to retain the contact assembly1204in the clutch collar1027as will be described in detail below.

In one embodiment, as shown inFIGS.24-27, the clutch collar1027has an alignment member receiving portion1210that receives an alignment member1207and that is flanked by a pair of spring receiving portions/spring pockets1214that receive the springs1208. The clutch collar1027also includes a pair of spring keeper retainer receiving portions1217that receive the spring keeper retainers1241therein. The pair of spring receiving portions/spring pockets1214is flanked by the pair of spring keeper retainer receiving portions1217. The alignment member receiving portion1210may have elliptical, oblong or other shaped configurations. The spring receiving portions/spring pockets1214may have circular or other shaped configurations. The spring keeper retainer receiving portions1217may have rectangular, square or other shaped configurations.

The contact assembly1204may include the spring keeper1236and the pair of compression springs1208all received in and retained by the clutch selector1027. The contact assembly1204may include the pair of springs1208that is received in and is non-removably coupled to the clutch collar1027. The springs1208are compression springs. The pair of compression springs1208is received in the spring pockets1214of the clutch collar1027and is configured to receive a pair of lateral legs1240of the spring keeper1236therein. The diameter of each of the pair of compression springs1208is sized to fit into the corresponding spring pockets1214of the clutch collar1027and also sized to receive the corresponding one of the pair of lateral legs1240of the spring keeper1236in the assembled configuration of the contact assembly1204. The pair of compression springs1208is positioned symmetrically on both sides of the alignment member1207. The configuration of the compression spring1208is similar to that of the corresponding compression spring208.

Referring toFIG.27, the spring keeper1236has the top plate/member1238, the alignment member1207, the pair of lateral legs1240and the pair of spring keeper retainers1241. The alignment member1207, the pair of lateral legs1240and the pair of spring keeper retainers1241extend downward and away from the top plate/member1238.

The alignment member1207is configured to be received in the alignment member receiving portion1210. The alignment member1207may be interchangeably referred to as alignment stanchion. The alignment member1207and the alignment member receiving portion1210have corresponding shaped configurations. The alignment member1207is configured to act as an alignment feature for the contact assembly1204when the contact assembly1204is assembled and is non-removably coupled to the clutch collar1027.

Each of the pair of lateral legs1240have cylindrical shaped configuration. Each of the pair of lateral legs1240may be interchangeably referred to as spring stanchion. The diameter of each of the pair of lateral legs1240is sized to fit into the corresponding springs1208in the assembled configuration of the contact assembly1204. When the contact assembly1204is assembled and is non-removably coupled to the clutch collar1027, the pair of lateral legs1240are aligned and received in the compression springs1208.

First end portions of the pair of spring keeper retainers1241are connected to the top plate/member1238. Opposing, second end portions of the pair of spring keeper retainers1241include catches1243. The catch1243may be interchangeably referred to as snap tab, lock portion/member, or retainer. The catch1243may be configured to extend/protrude, along the first transverse axis CP′T1-CP′T1, outwardly and away from the external surface of the each of the pair of spring keeper retainers1241. As will be clear from the detailed discussions below, the catches1243are configured to engage with portions of the clutch selector1027so as to non-removably couple the contact assembly1204to the clutch selector1027.

Each of the pair of spring keeper retainers1241may have a flexible configuration. Each of the pair of spring keeper retainers1241may have varying cross-sectional configuration (e.g., tapered cross-sectional configuration from their respective first end portion to their respective second end portion). This flexible and varying cross-sectional configuration of each of the pair of spring keeper retainers1241enable interengagement between the catches1243and their corresponding spring keeper retainer receiving portions1217in the clutch selector1027so as to non-removably couple the contact assembly1204to the clutch selector1027.

In one embodiment, the catches/snap tabs1243are configured to be inserted into the snap tab pockets/openings/spring keeper retainer receiving portions1217so as to non-removably couple the contact assembly1204to the clutch selector1027. The snap tabs1243and the snap tab pockets/openings1217have corresponding structures/configurations (e.g., (inclined) cam surfaces) to enable interengagement between the catches1243and the snap tab pockets/openings1217so as to non-removably couple the contact assembly1204to the clutch selector1027. For example, referring toFIG.33, when the snap tabs1243are inserted into the snap tab pockets/openings1217, the snap tabs1243may move along the inclined cam surfaces1299on the snap tab pockets/openings1217and then snapped into position in the snap tab pockets/openings1217, with lock surfaces1297holding the snap tabs1243in the retained/lock position.

In another embodiment, the interengagement between the catches1243and the spring keeper retainer receiving portions1217may be provided by other lock configurations, for example, detent lock, ball bearing lock, spring loaded lock, etc. that are configured to non-removably couple the contact assembly1204to the clutch selector1027.

In illustrated embodiment, as shown inFIG.27, the contact member1206includes an asymmetrical plate portion1229and includes the contact point or projection1230disposed thereon. The contact point1230is configured to engage with portions of the variable resistive element1202when the springs1208of the contact assembly1204bias the contact member1206against variable resistive element1202. The contact point1230may be interchangeably referred to potentiometer contact point. The contact point1230is configured to extend/protrude, along the longitudinal axis CP′L-CP′L, outwardly and away from the surface1256of the spring keeper1236.

In one embodiment, the spring keeper1236and its components may be made of a material that is configured to withstand the vibrations and/or other forces in the power tool10. In one embodiment, the spring keeper1236and its components is made of impact resistance material or impact absorbing material.

In one embodiment, the spring keeper1236includes the cutout portion1252at one end portion1254of the top plate/member1238to remove excess material of the spring keeper1236. In another embodiment, the cutout portion1252is optional.

FIGS.29-32show various procedures in a method of assembling the contact assembly1204of the clutch setting assembly1200and non-removably coupling the contact assembly1204of the clutch setting assembly1200to the clutch selector1027according to another embodiment of the present patent application.

FIGS.29and30show the clutch selector1027before and after the springs1208being inserted/received therein, respectively. In one embodiment, the springs1208of the contact assembly1204are inserted into the spring pockets1214in the clutch selector/collar1027.

FIGS.31and32show the clutch selector1027before and after the spring keeper1236being inserted therein, respectively. In one embodiment, the legs1240of the spring keeper1236are inserted into the openings1260of the springs1208, which are inserted in the spring pockets1214in the clutch selector/collar1027. In one embodiment, the alignment member1207of the spring keeper1236is inserted into the alignment member receiving portion1210in the clutch selector1027. In one embodiment, the pair of spring keeper retainers1241are inserted into the spring keeper retainer receiving portions1217so as to non-removably couple the contact assembly1204to the clutch selector1027. That is, the snap tabs1243of the spring keeper1236are inserted into the snap tab pockets1217of the clutch selector1027and the spring stanchions1240of the spring keeper1236are aligned with the compression springs1208in the clutch selector1027.

After the spring keeper1236is inserted into the clutch selector1027, the spring keeper1236pressed downwardly in the direction D toward the clutch selector/collar1027and against the force of the springs1208. The catches1243of the spring keeper1236align with and inserted into the snap tab pockets1217of the clutch collar1027when the contact assembly1204(including the contact member1206, the spring keeper1236, and the springs1208) is pressed down into the clutch collar1027.

Once the catches1243of the spring keeper1236are aligned with and received in the snap tab pockets1217of the clutch collar1027, the contact assembly1204(including the contact member1206, the springs1208and the spring keeper1236) is released (upwardly in the direction U). The catches1243of the spring keeper1236now abuts against the lock surfaces1297of the clutch selector1027, which retain the contact assembly1204(including the contact member1206, the springs1208and the spring keeper1236) in the clutch selector/collar1027(e.g., seeFIG.33). That is, the spring keeper1236is pressed down in the direction D until the snap tabs1243click (e.g., heard by an audible click) into the corresponding features in the clutch collar1027and then the spring keeper1236is released. The catches1243of the spring keeper1236interface with the lock surfaces1297of the clutch selector1027and keep the contact assembly1204(including the contact member1206, the springs1208and the spring keeper1236) retained in the clutch selector/collar1027.

FIG.32shows the contact assembly1204including the contact member1206and the spring keeper1236in its released and retained position. In one embodiment, the clutch selector/collar1027is then assembled to the power drill housing12, so that the contact point1230engages or makes contact with the variable resistive element/membrane potentiometer1202in the power drill housing12(e.g., seeFIG.34).

FIG.33shows cross-sectional views of the assembled spring keeper1236, the compression springs1208and the clutch collar1027.FIG.33also shows a cross-sectional view of the interface between the snap tab feature1243and the clutch collar1027.

FIG.34shows the clutch setting assembly1200including the contact assembly1204(including the contact member1206, the springs1208and the spring keeper1236), the clutch selector1027, and the variable resistive element1202.FIG.34shows the contact point1230making contact with the potentiometer/variable resistive element1202for the electronic clutch. In one embodiment, the springs1208bias the contact assembly1204toward the variable resistive element/membrane potentiometer1202to keep good contact between the contact point1230and the variable resistive element/membrane potentiometer1202. In one embodiment, as the clutch collar1027rotates to change the clutch setting, the contact member1206moves along with the clutch collar1027to engage the contact point1230at a different location of the variable resistive element/membrane potentiometer1202. This engagement changes the resistance of the variable resistive element/membrane potentiometer1202, allowing the controller for the electronic clutch to sense the position of the clutch collar1027.