GB2485578A - Programmable power tool controller - Google Patents

Programmable power tool controller Download PDF

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Publication number
GB2485578A
GB2485578A GB1019624.4A GB201019624A GB2485578A GB 2485578 A GB2485578 A GB 2485578A GB 201019624 A GB201019624 A GB 201019624A GB 2485578 A GB2485578 A GB 2485578A
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GB
United Kingdom
Prior art keywords
microcontroller
power
input
motor
control system
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Granted
Application number
GB1019624.4A
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GB2485578B (en
GB201019624D0 (en
Inventor
Shaun Michael Lovelass
Stephen Roe
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Black and Decker Inc
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Black and Decker Inc
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Priority to GB1019624.4A priority Critical patent/GB2485578B/en
Publication of GB201019624D0 publication Critical patent/GB201019624D0/en
Publication of GB2485578A publication Critical patent/GB2485578A/en
Application granted granted Critical
Publication of GB2485578B publication Critical patent/GB2485578B/en
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Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B25—HAND TOOLS; PORTABLE POWER-DRIVEN TOOLS; MANIPULATORS
    • B25F—COMBINATION OR MULTI-PURPOSE TOOLS NOT OTHERWISE PROVIDED FOR; DETAILS OR COMPONENTS OF PORTABLE POWER-DRIVEN TOOLS NOT PARTICULARLY RELATED TO THE OPERATIONS PERFORMED AND NOT OTHERWISE PROVIDED FOR
    • B25F3/00—Associations of tools for different working operations with one portable power-drive means; Adapters therefor
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J7/00—Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries
    • H02J7/0063—Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries with circuits adapted for supplying loads from the battery
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B25—HAND TOOLS; PORTABLE POWER-DRIVEN TOOLS; MANIPULATORS
    • B25F—COMBINATION OR MULTI-PURPOSE TOOLS NOT OTHERWISE PROVIDED FOR; DETAILS OR COMPONENTS OF PORTABLE POWER-DRIVEN TOOLS NOT PARTICULARLY RELATED TO THE OPERATIONS PERFORMED AND NOT OTHERWISE PROVIDED FOR
    • B25F5/00—Details or components of portable power-driven tools not particularly related to the operations performed and not otherwise provided for
    • G—PHYSICS
    • G05—CONTROLLING; REGULATING
    • G05B—CONTROL OR REGULATING SYSTEMS IN GENERAL; FUNCTIONAL ELEMENTS OF SUCH SYSTEMS; MONITORING OR TESTING ARRANGEMENTS FOR SUCH SYSTEMS OR ELEMENTS
    • G05B19/00—Programme-control systems
    • G05B19/02—Programme-control systems electric
    • G05B19/04—Programme control other than numerical control, i.e. in sequence controllers or logic controllers
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J7/00—Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries
    • H02J7/00032—Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries characterised by data exchange
    • H02J7/00038—Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries characterised by data exchange using passive battery identification means, e.g. resistors or capacitors
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02P—CONTROL OR REGULATION OF ELECTRIC MOTORS, ELECTRIC GENERATORS OR DYNAMO-ELECTRIC CONVERTERS; CONTROLLING TRANSFORMERS, REACTORS OR CHOKE COILS
    • H02P29/00—Arrangements for regulating or controlling electric motors, appropriate for both AC and DC motors
    • H02P29/02—Providing protection against overload without automatic interruption of supply
    • H02P29/032—Preventing damage to the motor, e.g. setting individual current limits for different drive conditions
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02P—CONTROL OR REGULATION OF ELECTRIC MOTORS, ELECTRIC GENERATORS OR DYNAMO-ELECTRIC CONVERTERS; CONTROLLING TRANSFORMERS, REACTORS OR CHOKE COILS
    • H02P7/00—Arrangements for regulating or controlling the speed or torque of electric DC motors
    • H02P7/06—Arrangements for regulating or controlling the speed or torque of electric DC motors for regulating or controlling an individual dc dynamo-electric motor by varying field or armature current
    • H02P7/18—Arrangements for regulating or controlling the speed or torque of electric DC motors for regulating or controlling an individual dc dynamo-electric motor by varying field or armature current by master control with auxiliary power
    • H02P7/24—Arrangements for regulating or controlling the speed or torque of electric DC motors for regulating or controlling an individual dc dynamo-electric motor by varying field or armature current by master control with auxiliary power using discharge tubes or semiconductor devices
    • H02P7/28—Arrangements for regulating or controlling the speed or torque of electric DC motors for regulating or controlling an individual dc dynamo-electric motor by varying field or armature current by master control with auxiliary power using discharge tubes or semiconductor devices using semiconductor devices
    • H02P7/285—Arrangements for regulating or controlling the speed or torque of electric DC motors for regulating or controlling an individual dc dynamo-electric motor by varying field or armature current by master control with auxiliary power using discharge tubes or semiconductor devices using semiconductor devices controlling armature supply only
    • H02P7/29—Arrangements for regulating or controlling the speed or torque of electric DC motors for regulating or controlling an individual dc dynamo-electric motor by varying field or armature current by master control with auxiliary power using discharge tubes or semiconductor devices using semiconductor devices controlling armature supply only using pulse modulation

Abstract

A power-tool control system comprises a programmable microcontroller 10 having an output 101 for driving a motor 12 of a power tool and a selection device 14 to provide an input signal to the microcontroller 10. The selection device has plural states, each representing a different type of power tool, and for each state the microcontroller provides a respective set of output signals to the motor. The micro-controller can comprise an input 102 for detecting different types of battery and can supply a different output signal to the motor depending on the type of battery and, should it detect a LI-ion battery can measure the state of charge of the battery. The microcontroller can also comprise an output 104 connected to a status display 16.; and inputs 105, 106 receiving user alterable selections of economy/sport mode and speed. A shunt 20 can provide current feedback through an operational amplifier 107 to the microcontroller which can vary the current according to the motor load. The selection device 14 can be a header that is connected during manufacture in a configuration that selects a pre-programmed operational program for driving the motor that is appropriate to the tool type, such as a grass trimmer, leaf blower or a hedge trimmer.

Description

POWER-TOOL CONTROL SYSTEM
The present invention concerns a power-tool control system comprising a programmable microcontroller. The use of electronic control systems in power tools is well known. Often, such control systems comprise a circuit board with passive electronic components hard-wired onto it, but the use of programmable microcontrollers in such control systems is also known. In this way, either by the use of passive components or by the use of a programmable microcontroller, or both, the operation of a power tool may be controlled in a desired way dependent upon one or more inputs supplied to the control system by a user. For example, in a very simple case, a user input to the control system may comprise just an on/off switch for the power tool, but rather than the on/off switch being connected directly to a motor of the power tool, the control system may be adapted to provide the motor with a "soft" start, whereby the rate of revolution of the motor is steadily increased at switch-on, to avoid putting an undue load on a power supply of the power tool.
However, in the prior art, such control systems are generally tailored to suit the particular type of power tool for which they are intended. This means that each such control system is particular to a particular type of power tool. Consequently, control systems must be designed and manufactured independently for different power tools, even if such different power tools are being manufactured side-by-side in the same factory. This has adverse implications in the cost and efficiency of manufacture of such power tools. Accordingly, it would be desirable to provide a power-tool control system which can be incorporated in the manufacture of a range of power tools, thereby improving the efficiency of production and saving manufacturing costs.
However, in order to achieve this, the problem of how to provide a power-tool control system which can be incorporated in a range of different power tools, in spite of the different operational requirements of such different tools must be overcome. The present invention seeks to overcome this problem.
Accordingly, in a first aspect, the present invention provides a power-tool control system comprising: a programmable microcontroller having an output for driving a motor of a power tool; the power-tool control system further comprising a selection device for providing an input signal to the microcontroller, the selection device having a plurality of states, each of said states respectively representing a different type of power tool, wherein when said selection device is put in a first one of said plurality of states, said selection device provides a respective first input signal to said microcontroller, whereby said microcontroller is enabled to provide a respective first set of output signals to said motor, and when said selection device is put in a second one of said plurality of states, said selection device provides a respective second input signal to said microcontroller, whereby said microcontroller is enabled to provide a respective second set of output signals to said motor.
Thus, the microcontroller can be pre-programmed with at least two different operational programs for providing different respective sets of output signals for driving the respective motors of at least two different power tools, and which one of these two operational programs is enabled is determined by the state of the selection device. The state of the selection device may be pre-set in the factory during manufacture and then the same control system may be incorporated into two respectively different power tools, just by altering the setting of the selection device.
The same invention may of course be extended to a plurality of power tools greater than just two by using exactly the same principle, with the number of different operational programs for providing different sets of output signals for driving the respective motors of different power tools being increased accordingly.
In a second aspect, the present invention also provides a method of manufacturing a plurality of different types of power tool, the method comprising the steps of: providing a plurality of programmable microcontrollers, each of the microcontrollers having an output for driving a motor of a power tool; programming each of the microcontrollers with a plurality of different operational programs for providing different respective sets of output signals for driving the respective motors of the plurality of different types of power tool; incorporating a selected one of said microcontrollers into a control system further comprising a selection device for providing an input signal to the selected microcontroller, the selection device having a plurality of states, each of said states respectively representing a different one of said plurality of different types of power tool; putting the selection device into one of said plurality of states corresponding to a particular one of said plurality of different types of power tool; and incorporating said control system into an example of said particular one of said plurality of different types of power tool.
Thus each of the microcontrollers may be programmed in an identical fashion with all of the required operational programs for providing different respective sets of output signals for driving the respective motors of the plurality of different types of power tool, but any one of the microcontrollers may be put in any type of power tool for which it has been programmed, and the operational program for the power tool which is enabled in the microcontroller is determined by the state into which the selection device has been put. Thus, a machine in an assembly-line for producing power tools or an unskilled assembly-line worker may rapidly put the selection device into whichever state corresponds to the type of power tool into which the control system containing the microcontroller is to be incorporated. Consequently, control systems incorporating the same components may be incorporated into a range of different types of power tool, which both saves costs in ordering materials and increases the speed and efficiency of their manufacture.
The selection device may be any one of an array of header pins, a pattern of punched-out or soldered-in tracks on a circuit board, a multistate latching switch, a "bed of nails", or any other such known selection device. The output signals provided at the output of the microcontroller for driving the motor may typically be provided in the form of a pulse-width modulated (PWM) signal for driving a field-effect transistor (FET) which draws current from a power supply to power the motor.
In a preferred embodiment, the programmable microcontroller of the power-tool control system further comprises an input for detecting different types of battery power supply, wherein when the input receives a first signal indicating a first type of battery power supply, the microcontroller is enabled to provide a respective first set of output signals to the motor, and when the input receives a second signal indicating a second type of battery power supply, the microcontroller is enabled to provide a respective second set of output signals to the motor.
Thus, the microcontroller can be pre-programmed with at least two different operational programs for providing different respective sets of output signals for driving the motor of a power tool from different types of battery power supply, and which one of these two operational programs is enabled is determined by the signal detected at the input of the microcontroller. The same idea may of course be extended to a plurality of different types of battery power supply greater than just two by using exactly the same principle, with the number of different operational programs for providing different sets of output signals for driving the motor from different types of battery power supply being increased accordingly.
This has the advantage that the output of the microcontroller for driving the motor may draw on any one of the different types of battery power supply detected by the input. For example, the input for detecting different types of battery power supply may detect nickel cadmium (NiCd) or nickel metal-hydride (NiMH) battery types on the one hand and lithium-ion (Li-ion) battery types on the other. This causes the output signals at the output of the microcontroller to be adapted to the power level and supply characteristics of the different battery types and means that the power-tool control system may be incorporated into power tools supplied by a range of different battery types without any modification, which both saves costs in ordering materials and increases the speed and efficiency of their manufacture.
Preferably, the microcontroller comprises a third input for determining the charge level of the battery, so that in the case that the input of the microcontroller for detecting the type of battery detects a Li-ion type battery, the microcontroller can also measure the state of charge of the battery. This is possible in the case of Li-ion type batteries because whereas the state of charge of NiCd and NiMH type batteries decays steadily, Li-ion type batteries remain at a roughly constant charge level before decaying rapidly. Thus, once the input for detecting different types of battery power supply has already determined that a Li-ion type battery is being used to supply power to the motor, the input for determining the charge level of the battery may find the charge level of the battery to be greater than, equal to or less than a predetermined level, which respectively correspond to the battery being fully charged, in the process of decaying or empty. The predetermined level may be set by a potential divider connected across the input of the microcontroller for determining the charge level of the battery, which has its point of division set in advance according to the expected decay characteristics of a Li-ion type battery.
This information may then be used to modify the set of signals output by the microcontroller for driving the motor, according to the charge remaining in the battery.
Preferably, the microcontroller has a second output, and the control system further comprises a display having an input connected to the second output of the microcontroller. The display may be used to indicate the type of power tool for which operation of the microcontroller is enabled by the selection device, the type of battery power supply detected by the microcontroller, the charge level of the battery, or any combination of these three, based upon signals from the second output of the microcontroller.
In a further preferred embodiment, the microcontroller also comprises an input for receiving a mode-selection signal and the control system further comprises a user-operable switch connected thereto whereby a user may enter a mode selection signal, and the microcontroller varies the output signals at the output for driving the motor based on the mode-selection signal received by the input. In this way, a user may select a mode in which the power tool should operate, for example an economy mode to reduce battery power consumption or a power boost mode to increase power to the motor during heavy load conditions. The microcontroller may store the most recently received mode-selection signal in a flash memory even when the power supply to the control system is switched off, so that the mode of operation is recovered again at switch-on. In addition, the aforementioned display may also indicate which one of a plurality of different sets of output signals corresponding to the different modes selected by the user is being supplied by the output of the microcontroller for driving the motor.
A further preferred possibility is that the microcontroller may alternatively or additionally comprise another user-operable input, whereby a user may vary the overall level of power drawn on by the output of the microcontroller for driving the motor, thus adjusting the speed of the motor in a continuous fashion. This may be achieved, for example, by connecting this user-operable input to a potentiometer.
Still yet another possibility is that the same input of the microcontroller may be used for both receiving the mode selection signal and for varying the overall level of power drawn on by the output of the microcontroller for driving the motor. This may be achieved, for example, by connecting the input to a combined potentiometer and multi-state switch. This has the advantage of freeing up another pin of the microcontroller for receiving an input from the selection device, thereby allowing the same control system to be incorporated into a greater number of different types of power tool.
Optionally, the microcontroller comprises an operational amplifier (op amp) connected in a current feedback loop across a shunt to a current sense input of the microcontroller. This allows the microcontroller to give current compensation depending on the state of charge of the battery power supply, and also has the advantage of smoothing out any undesirable transients in the current.
Additionally, the microcontroller may also be programmed to vary the current supplied to the motor depending on the load placed on the motor as measured by the feedback to the current sense input. Depending on how the microcontroller has been programmed, the microcontroller could then change the output signals at the output for driving the motor to a power boost mode to increase power to the motor during heavy load conditions. For example, if the control system of the invention were to be incorporated into a drill, this would increase the rate of revolution of the drill's motor whenever the drill struck something hard, or if the control system of the invention were instead incorporated into a grass trimmer, this would increase the rate of revolution of the trimmer's motor whenever the trimmer entered long grass.
Finally, the microcontroller may also store the number of times that the power tool is switched on and off. If the control system also comprises a display, this data may be used by the microcontroller, for example, to send a signal to the display to indicating when the power tool has been switched on a predetermined number of times, for example to tell the user that the power tool should be serviced.
Further features and advantages of the present invention will be better understood by reference to the following detailed description, which is given by way of example and in association with the accompanying drawings, in which: Fig. I is a schematic circuit diagram of a power-tool control system according to a preferred embodiment of the present invention.
Referring to Fig. 1, there is shown a power-tool control system, comprising a microcontroller 10 having an output 101 for driving a motor 12 of a power tool. Fig. I has a horizontal co-ordinate I to 8 along the abscissa and a vertical co-ordinate A to H along the ordinate, which will be referred to occasionally below to help locate the components of the control system shown in Fig. 1. Apart from the microcontroller 10 at C4 to G4, the control system also comprises a selection device 14 at E7 to F7 for providing an input signal to the microcontroller 10. In the present case, the selection device 14 is an array of header pins connected to two input pins of the microcontroller, each of which has a binary input. A header is used during manufacture of the power tool to connect two of the header pins together in different configurations in the manner shown in the drawing at E8 to F8. Each of the different configurations shown in the drawing represents, in turn, a grass trimmer, a leaf blower and a hedge trimmer. Thus, the selection device has a plurality of states, each of which respectively represents a different type of power tool. The microcontroller 10 is pre-programmed with different operational programs for providing different respective sets of output signals at its output 101 for driving the respective motors of a grass trimmer, a leaf blower and a hedge trimmer in different manners. However, since the selection device 14 has been put in a particular state during manufacture of the power tool, which state represents only a particular one of these different power tools, the selection device provides a corresponding input signal to the microcontroller 10. This enables the microcontroller to provide a corresponding set of output signals to the motor 12 which is then appropriate for the particular power tool into which the control system has been incorporated during manufacture.
Power for the control system is provided by a battery power supply at terminals B÷ and B-, respectively located in Fig. I at H8 and B8. A user-operated non-latching switch (also at H8) switches the power supply to both the motor 12 and the control system on and off in a conventional fashion. In the event that the selection device 14 has been set to represent a power tool which requires rapid braking, the off" state of the non-latching switch is also connected in a reverse sense to the power tool via the dashed line at H8 to El to provide a back e.m.f., whereby the motor 12 is brought rapidly to a halt as soon as the non-latching switch reaches the "off" position. In either case, the microcontroller 10 also stores a number of times that the power tool is switched on and off via the switch at H8.
Apart from the power supply terminals B÷ and B-, the microcontroller of this embodiment further comprises an input 102 for detecting different types of battery power supply, which input 102 is connected to the FET shown in Fig. I at D6. The FET is also connected to an ID terminal of the battery at D8 in the manner shown in Fig. I. Thus, by the use of a FET, the microcontroller 10 is able to detect the type of battery chemistry of the power supply without drawing more than just a few microamps of current from the battery, and certainly less than 100 microamps. The microcontroller 10 is pre-programmed with two different operational programs, one of which is appropriate for a battery having nickel cadmium (NiCd) or nickel metal-hydride (NiMH) chemistry and the other of which is appropriate for a battery having lithium-ion (Li-ion) chemistry. Thus, when the input 102 of the microcontroller receives a signal indicating a battery with NiCd or NiMH chemistry, the microcontroller is enabled to provide a correspondingly appropriate set of output signals via output 101 to motor 12, and when the input 102 receives a signal indicating a battery with Li-ion chemistry, the microcontroller is enabled to provide a correspondingly different set of output signals via output 101 to motor 12 instead.
Thus, the output 101 is able to draw on any one of the different types of battery power supply detected by the input 102.
The microcontroller 10 also has an input 103 for determining the charge level of the battery when the input 102 for detecting the type of battery has detected a Li-ion type battery. Input 103 is connected to a potential divider, as represented in Fig. I by the serial resistors at D6 and G6, so that the microcontroller can measure the state of charge of the battery by comparing it with the potential at the point between the two resistors. This potential is set in advance during manufacture of the control system, according to the expected decay characteristics of a Li-ion type battery. The charge level of the battery detected by the microcontroller is then used by the microcontroller to modify the set of signals sent from output 101 for driving the motor 12, according to the charge remaining in the battery.
The control system of Fig. 1 further comprises a display 16 and the microcontroller 10 has a second output 104 which is connected to an input of the display. Output 104 actually comprises a plurality of pins on the microcontroller chip, as shown in Fig. 1. The display 16 has a first portion 161 for indicating the state of charge of the battery power supply determined by input 103, comprising a red, an amber and a green part. When input 103 detects that the battery is fully charged, all three coloured parts of portion 161 of the display 16 are illuminated by signals from output 104. When the input 103 detects that the battery is partially discharged, only the red and amber parts of this portion 161 are illuminated by signals from output 104. And when the input 103 detects that the battery is discharged, only the red part of the display portion 161 is illuminated by signals from output 104.
Display 16 also has a second portion 162 for indicating a mode of operation of the power tool. The control system further comprises a user-operable switch 18 shown in Fig. I at D3. User-operable switch 18 is connected to a further input 105 of the microcontroller 10, whereby a user may enter a mode-selection signal, and the microcontroller 10 varies the output signals at output 101 for driving the motor 12 based on the mode-selection signal received by input 105. In this embodiment, the control system provides the power tool with two modes of operation: an economy mode and a "sport" mode. Use of the economy mode extends the run-time of the battery power supply by using the power sparingly, whereas the "sport" mode increases the power supplied to motor 12 by output 101 when a user wishes to tackle tougher jobs. The mode of operation selected by a user via switch 18 is latched by the microcontroller 10 and also causes the microcontroller to generate an output signal at some of the pins of output 104 of microcontroller 10 which are connected to the second portion 162 of display 16. This portion 162 of display 16 comprises a first part for indicating when the power tool is operating in economy mode and a second part for indicating when the power tool is operating in sport mode. These two parts of display portion 162 are illuminated alternately by signals from output 104, depending on the mode selected by the user via switch 18.
In Fig. 1, the microcontroller 10 also comprises a user-operable input 106 for varying the overall level of power drawn on by the output 101 of the microcontroller for driving the motor 12. Input 106 is connected to a potentiometer as shown in Fig. I at F5. By varying the setting of this potentiometer, a user is able to adjust the speed of motor 12 in a continuous fashion. However, microcontroller 10 is pre-programmed during manufacture only to respond to signals from input 106 when selection device 14 has been set in the factory to represent a leaf blower. Thus with this setting of selection device 14, the air speed generated by the leaf blower varies as the user adjusts the potentiometer at F5. On the other hand, if the control system is instead incorporated into a grass trimmer or a hedge trimmer, the potentiometer at F5 is preset in the factory at an optimum level and is not exposed through an outer casing of either of these two different power tools, so that its setting cannot be adjusted by a user. If the control system of Fig. I is incorporated into a grass trimmer or a hedge trimmer, the signals from selection device 14 therefore cause microcontroller 10 to ignore any signals on input 106, and the grass or hedge trimmer operates at a uniform speed in each mode of operation selected by a user.
Although not shown in Fig. 1, in an alternative embodiment, the potentiometer at F5 may be combined with the mode-selection switch 18, for example by programming the microcontroller in the factory to switch from economy to "sport" mode when the setting of the potentiometer passes a certain value. This would then free up input 105 to be re-assigned to receive an additional input signal from selection device 14. In this way, the number of different power tools which could be controlled by the control system could be increased by a factor of 2, using the same binary code as described above.
As shown in Fig. 1, microcontroller 10 comprises an operational amplifier 107 connected in a current feedback loop across a shunt 20 to a current sense input 108 of the microcontroller. The output 101 of the microcontroller for driving motor 12 varies the current supplied to the motor depending on a load placed on the motor, as measured by the feedback to the current sense input 108. In addition, microcontroller 10 is programmed to ramp up the current supplied to motor 12 at switch-on to give a "soft" start in a conventional fashion, and also to shut down the FET shown at Dl either when the motor is detected by the current feedback loop to be under an overload condition, in which the motor is drawing a current above a predetermined level, or when the input 103 to the microcontroller detects that the battery is discharged.
Finally, microcontroller 10 also has a master-clear input 109 of a conventional type. This input 109 detects when power to the microcontroller is switched on, and cleanly resets the microcontroller each time, without any corruption to the selected operational program.
The control system shown in Fig. I is particularly suited for use in a method of manufacturing a plurality of different types of power tool, wherein the method comprises the following steps. Firstly, there is provided a plurality of programmable microcontrollers 10 of the type shown in Fig. 1, each of which has an output 101 for driving a motor 12 of a power tool, and each of these microcontrollers is programmed with a plurality of different operational programs for providing different respective sets of output signals for driving the respective motors of the plurality of different types of power tool. One of these microcontrollers is then selected and incorporated into a control system of the type shown in Fig. 1, which further comprises a selection device 14 for providing an input signal to the selected microcontroller in the manner described above. The selection device 14 is then put into a state corresponding to a particular one of the plurality of different types of power tool during manufacture, and the control system is incorporated into an example of that particular type of power tool, so that the operational program for that type of power tool which has been selected by the selection device 14 is also the one appropriate to that particular type of power tool. The same last steps may then be repeated for other ones of the plurality of microcontrollers, thereby giving a range of different power tools, all of which have appropriate and correspondingly different operational programs, but which nonetheless contain the same control system.
Whereas the present invention has been particularly described above using the example of different types of outdoor or garden power tool, it could equally well be applied in the context of a completely different range of power tool types, for example a range comprising a drill, a sander, a screwdriver and a jigsaw.

Claims (12)

  1. CLAIMS1. A power-tool control system comprising: a programmable microcontroller (10) having an output (101) for driving a motor (12) of a power tool; chaiacterized by: a selection device (14) for providing an input signal to said microcontroller (10), said selection device having a plurality of states, each of said states respectively representing a different type of power tool, wherein when said selection device is put in a first one of said plurality of states, said selection device provides a respective first input signal to said microcontroller, whereby said microcontroller is enabled to provide a respective first set of output signals to said motor (12), and when said selection device is put in a second one of said plurality of states, said selection device provides a respective second input signal to said microcontroller, whereby said microcontroller is enabled to provide a respective second set of output signals to said motor.
  2. 2. A power-tool control system according to claim 1, wherein the programmable microcontroller (10) further comprises an input (102) for detecting different types of battery power supply, wherein when said input (102) receives a first signal indicating a first type of battery power supply, said microcontroller is enabled to provide a respective first set of output signals to said motor (12), and when said input (102) receives a second signal indicating a second type of battery power supply, said microcontroller is enabled to provide a respective second set of output signals to said motor (12), whereby the output (101) of the microcontroller for driving the motor may draw on any one of the different types of battery power supply detected by the input (102).
  3. 3. A power-tool control system according to claim 2, wherein the microcontroller (10) further comprises an input (103) for determining the charge level of the battery, whereby when said input (102) of the microcontroller for detecting the type of battery detects a Li-ion type battery, the microcontroller can measure the state of charge of the battery.
  4. 4. A power-tool control system according to any one of the preceding claims, wherein the microcontroller (10) has a second output (104), and the control system further comprises a display (16) having an input connected to the second output of the microcontroller.
  5. 5. A power-tool control system according to any one of the preceding claims, wherein the microcontroller (10) comprises an input (105) for receiving a mode-selection signal and the control system further comprises a user-operable switch (18) connected thereto whereby a user may enter a mode-selection signal, and the microcontroller varies the output signals at output (101) for driving the motor based on the mode-selection signal received by said input (105).
  6. 6. A power-tool control system according to any one of the preceding claims, wherein the microcontroller (10) comprises a user-operable input (106) for varying the overall level of power drawn on by the output (101) of the microcontroller for driving the motor, whereby the speed of the motor may be adjusted in a continuous fashion.
  7. 7. A power-tool control system according to claim 6 as dependent on claim 5, wherein the input (105) for receiving a mode-selection signal and the user-operable input (106) for varying the overall level of power drawn on by the output (101) of the microcontroller for driving the motor are one and the same input.
  8. 8. A power-tool control system according to any one of the preceding claims, wherein the microcontroller (10) comprises an operational amplifier (107) connected in a current feedback loop across a shunt (20) to a current sense input (108) of the microcontroller.
  9. 9. A power-tool control system according to claim 8, wherein the output (101) of the microcontroller for driving a motor (12) varies the current supplied to the motor depending on a load placed on the motor, as measured by the feedback to the current sense input (108).
  10. 10. A power-tool control system according to any one of the preceding claims, wherein the microcontroller (10) stores a number of times that the power tool is switched on and off.
  11. 11. A power tool control system substantially as hereinbefore described with reference to the accompanying drawing.
  12. 12. A method of manufacturing a plurality of different types of power tool, the method comprising the steps of: providing a plurality of programmable microcontrollers, each of the microcontrollers having an output for driving a motor of a power tool; programming each of the microcontrollers with a plurality of different operational programs for providing different respective sets of output signals for driving the respective motors of the plurality of different types of power tool; incorporating a selected one of said microcontrollers into a control system further comprising a selection device for providing an input signal to the selected microcontroller, the selection device having a plurality of states, each of said states respectively representing a different one of said plurality of different types of power tool; putting the selection device into one of said plurality of states corresponding to a particular one of said plurality of different types of power tool; and incorporating said control system into an example of said particular type of power tool.
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US11569765B2 (en) 2019-10-11 2023-01-31 Black & Decker Inc. Power tool receiving different capacity battery packs

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EP0304574A1 (en) * 1987-08-07 1989-03-01 Festo KG Power supply device for a variety of connectable tools
US20020134811A1 (en) * 2001-01-29 2002-09-26 Senco Products, Inc. Multi-mode power tool utilizing attachment
EP1473825A2 (en) * 2003-04-30 2004-11-03 BLACK & DECKER INC. Generic AC motor control system
WO2007044930A2 (en) * 2005-10-12 2007-04-19 Black & Decker Inc. Control and protection methodologies for a motor control module
EP2324779A1 (en) * 2009-11-09 2011-05-25 Jean-Pierre Py Surgical device

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EP0304574A1 (en) * 1987-08-07 1989-03-01 Festo KG Power supply device for a variety of connectable tools
US20020134811A1 (en) * 2001-01-29 2002-09-26 Senco Products, Inc. Multi-mode power tool utilizing attachment
EP1473825A2 (en) * 2003-04-30 2004-11-03 BLACK & DECKER INC. Generic AC motor control system
WO2007044930A2 (en) * 2005-10-12 2007-04-19 Black & Decker Inc. Control and protection methodologies for a motor control module
EP2324779A1 (en) * 2009-11-09 2011-05-25 Jean-Pierre Py Surgical device

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US11569765B2 (en) 2019-10-11 2023-01-31 Black & Decker Inc. Power tool receiving different capacity battery packs

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GB201019624D0 (en) 2010-12-29

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