WO2022178771A1

WO2022178771A1 - Power tools and methods of producing a notification to a user

Info

Publication number: WO2022178771A1
Application number: PCT/CN2021/077940
Authority: WO
Inventors: Huanfa XIE; Kaijia SUN; Shunkai PENG; Haibo Ma; Chao Wen; Yongmin Li
Original assignee: Techtronic Cordless Gp
Priority date: 2021-02-25
Filing date: 2021-02-25
Publication date: 2022-09-01
Also published as: CN115250643A; EP4073915A4; EP4073915A1

Abstract

The present invention relates to a power tool adapted to produce a notification to a user. The power tool comprises a sensor configured to sense a fault condition of the power tool; a motor driving circuit connected to the sensor, and configured to provide a motor driving signal based on the fault condition of the power tool; and a motor connected to the motor driving circuit and adapted to be driven by the motor driving signal from the motor driving circuit to produce the notification. The notification is in the form of an audible sound and/or a perceivable vibration via which the user is notified about the fault condition.

Description

POWER TOOLS AND METHODS OF PRODUCING A NOTIFICATION TO A USER

FIELD OF INVENTION

This invention relates to power tools, and in particular motor-driven power tools.

BACKGROUND OF INVENTION

Electric power tools are widely deployed in various industries due to their convenience to use. While these power tools greatly enhance working efficiencies of users, however, fault conditions or other problems of power tools occur from time to time during use. Traditionally, users of the power tools usually judge the fault conditions through experience. Sometimes when the faults are not noticeable, the users may not even be aware of the fault conditions of the power tools, until the tools are eventually broken because of continuous operation with the fault condition. Alternatively, during the operation of traditional power tools, when an abnormal condition is detected, the tool will immediately cut off the output and stop running, which does not directly indicate to the user that the tool is in the abnormal condition.

For many of the power tools, the fault conditions happen during use of the tool when the tool member (e.g. a saw blade) become stuck in the workpiece in such a way that the tool member can no longer move relative to the workpiece (a.k.a. jammed) . In this case, the motor of the power tool may be burned due to the long lasting high current flowing through the motor even if there are protecting circuits in the power tool. The detection and notification of the fault problem thus have to be quick enough so that rotation of the motor can be stopped quickly.

SUMMARY OF INVENTION

The present invention In the light of the foregoing background, it is an object of the present invention to provide an alternate electric tool and its operation method of producing a notification to a user, if a fault condition is detected, which eliminates or at least alleviates the above technical problems.

The above object is met by the combination of features of the main claim; the sub-claims disclose further advantageous embodiments of the invention.

One skilled in the art will derive from the following description other objects of the invention. Therefore, the foregoing statements of object are not exhaustive and serve merely to illustrate some of the many objects of the present invention.

Accordingly, the present invention, in one aspect, is a power tool adapted to produce a notification to a user. The power tool comprises a sensor configured to sense a fault condition of the power tool; a motor driving circuit connected to the sensor, and configured to provide a motor driving signal based on the fault condition of the power tool; and a motor connected to the motor driving circuit and adapted to be driven by the motor driving signal from the motor driving circuit to produce the notification. The notification is in the form of an audible sound and/or a perceivable vibration via which the user is notified about the fault condition.

Preferably, the motor is adapted to be driven at different powers and/or frequencies under a modulation of the motor driving signal.

More preferably, the modulation of the motor driving signal includes one or more of the followings: interrupting a power to the motor, reducing the power to the motor to a non-zero value, increasing the power to the motor, pulsing the motor, braking the motor, and actuating a clutch.

Alternatively, wherein the motor is adapted to be driven using PWM (Pulse Width Modulation) or PFM (Pulse Frequency Modulation) to produce the notification.

According to one variation of the preferred embodiments, the modulation of motor by PWM or PFM comprises at least one of the followings actions: a) applying a plurality of different driving modes to the motor; b) applying a plurality of different duty time of PWM or PFM; c) applying a plurality of different cycle time of PWM or PFM; d) intermittently stopping and restarting the motor; and e) applying a plurality of different motor currents. Preferably, the plurality of different driving modes includes but not limited to a high speed rotation mode, a medium speed rotation mode, a low speed rotation mode, and other driving modes well-known in this field.

Preferably, each one of the actions a) to e) above is performed within a single motor driving cycle, or is performed when the motor enters from one driving cycle to another driving cycle.

Alternatively, the modulation comprises at least two modes of different powers or frequencies of motor, and the powers or frequencies switch periodically.

According to another variation of the preferred embodiments, the sensor comprises at least one of: a temperature detector for detecting a temperature of the motor to generate a temperature signal; a current detector for detecting current flowing through the motor to generate a current signal; a voltage detector for detecting a voltage across the motor to generate a voltage signal; and a rotation speed detector for detecting a rotation speed of the motor to generate a rotation speed signal. The motor driving circuit receives at least one of the temperature, current, voltage and rotation speed signals to determine a corresponding fault condition of the power tool to provide the motor driving signal. Preferably, the sensor can be configured to further include a user input detector for detecting a user’s input or behavior of control including but not limiting to a selected working mode, and an a position of trigger when actuated. Once the working mode is selected or switched, or the trigger is actuated, a signal will be provided by the sensor for further execution.

Preferably, the fault condition is reported if at least one of the temperature, current, voltage, rotation speed signal exceeds a given threshold, or exceeds a given threshold over a given period of time, or changes dramatically over a given period of time.

More preferably, the motor driving circuit is further configured to audit the fault condition, if the fault condition eliminates, the motor driving circuit is configured to generate a signal to re-operate the power tool.

In another aspect, the present invention is a method of producing a notification to a user. The method comprises the steps of, a) sensing a fault condition of the power tool by a sensor; b) providing a motor driving signal based on the fault condition of the power tool by a motor driving circuit connected to the sensor; and c) producing the notification by the motor connected to the motor driving circuit and adapted to be driven by the motor driving signal from the motor driving circuit. The notification is in the form of an audible sound and/or a perceivable vibration via which the user is notified about the fault condition.

Alternatively, the notification is produced by the motor which is adapted to be driven using PWM or PFM.

According to one variation of the preferred embodiments, the modulation of motor by PWM or PFM comprises at least one of the followings actions, a) applying a plurality of different driving modes to the motor; b) applying a plurality of different duty time of PWM or PFM; c) applying a plurality of different cycle time of PWM or PFM; d) intermittently stopping and restarting the motor; and e) applying a plurality of different motor currents.

Alternatively, wherein the modulation comprises at least two modes of different output powers or frequencies of motor, and the powers or frequencies switch periodically.

According to another variation of the preferred embodiments, one or more operation parameters of the power tool are monitored by the sensor to generate one or more detected signals to determine the fault condition of the power tool, the detected signal comprises at least one of: a temperature signal, detected by a temperature detector for detecting a temperature of the motor; a current signal, detected by a current detector for detecting current flowing through the motor; a voltage signal, detected by a voltage detector for detecting a voltage across the motor; and a rotation speed signal, detected by a rotation speed detector for detecting a rotation speed of the motor. The motor driving circuit receives at least one of the temperature, current, voltage and rotation speed signals to determine a corresponding fault condition of the power tool to provide the motor driving signal.

Preferably, the fault condition is reported if any of the temperature, current, voltage, and rotation speed signal exceeds a given threshold, or exceeds a given threshold over a given period of time, or changes dramatically over a given period of time.

More preferably, the method further comprises a step of auditing the fault condition by the motor driving circuit, wherein if the fault condition eliminates, the power tool is configured to re-operate by modulation of a signal generated by the motor driving circuit.

The advantage of the present invention is that it can timely provide the user with a fault notification or alarm of the power tool so that the user is aware of a fault condition of the power tool, before the power tool goes shut-down in order to avoid further damage to the power tool. In addition, the present invention uses the inherent brushed or brushless motor of the power tool as a device for generating alarms and notifications. In another words, there is no other component (such as buzzers, warning lights, etc., and their driving circuits) required to be installed or incorporated into the power tool, so that there is no additional hardware cost to implement the notification functions or added circuit complexity. Since the internal mechanical and electronic structure of electric tools are not required to be redesigned, the present invention can be widely applied to existing designs of power tools.

Furthermore, compared with the prior art documents that often use a buzzer alarm or a flashing of the warning light to provide an alarm or notification, which is not intuitive and noticeable sometimes, the invention uses a perceivable vibration and /or audible sound generated by the motor to provide the alarm or notification, which are more intuitive, effective and can attract the user's attention better. For example, for traditional power tools with a buzzer for generating warning sound, the power of the buzzer is limited and such warning sound is easily overwhelmed by the operation noise of the power tool (e.g. saw cutting) or environment noise in the worksite. However, power tools according to some embodiments of the invention use the motor to generate unusual sounds which is much louder than that from a buzzer, so the user is much easier to get notified of the abnormal condition. The unusual vibration caused to the power tool by the motor also serve as a unique and perceivable notification to the user which is not seen in traditional power tools.

BRIEF DESCRIPTION OF FIGURES

The foregoing and further features of the present invention will be apparent from the following description of preferred embodiments which are provided by way of example only in connection with the accompanying figures, of which:

Fig. 1 is an illustration of a power tool internal structure according to a first embodiment of the present invention.

Fig. 2 shows a schematic circuit diagram of the power tool in Fig. 1.

Fig. 3 shows a schematic circuit diagram of the sensor in Fig. 2.

Fig. 4 shows a flowchart of an exemplary motor control method according to a second embodiment of the present invention.

Fig. 5 shows a flowchart of an exemplary motor control method according to a third embodiment of the present invention.

Fig. 6 shows a flowchart of an exemplary motor control method according to a fourth embodiment of the present invention.

Fig. 7 shows a flowchart of an exemplary motor control method according to a fifth embodiment of the present invention.

Fig. 8 shows a flowchart of an exemplary motor control method according to a sixth embodiment of the present invention.

Fig. 9 shows a flowchart of an exemplary motor control method according to a seventh embodiment of the present invention.

Fig. 10 shows a schematic diagram of the PWM to modulate the power tool in Fig. 1

Fig. 11 shows a schematic diagram of operation status of the power tool in Fig. 1.

Figs. 12A to 12H show examples of different PWM signals to modulate the driving signal of the motor according to various embodiments of the invention.

In the drawings, like numerals indicate like parts throughout the several embodiments described herein.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Embodiments of the present invention now will be described more fully with reference to the accompanying drawings, in which embodiments of the invention are shown. The present invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. Like reference numerals refer to like elements throughout this application.

Referring to Fig. 1, according a first embodiment of the invention there is a provided a portable power tool 100 which may be a corded or cordless (battery-powered) portable device, such as a screwdriver, drill, etc. The power tool 100 includes a housing 102, which accommodates most of the essential components for normal operation of the power tool 100 including a motor 104, a transmission gear assembly 106, a rotary output component 108, a motor driving circuit 110, and a power supply module 112. The motor 104 can be a brushed or brushless motor. The transmission gear assembly 106 is coupled between the motor 104 and the output component 108 to provide an altered output driving force for example with different speeds and torques. The power supply module 112 can be a battery pack in the case of a cordless power tool, or it can be an AC-DC convertor in the case of a corded power tool where the power tool 100 is connected to mains supply via a power cord (not shown) .

Turning now to Fig. 2, the motor driving circuit 110 of the power tool 100 is connected to the motor 104 for controlling the operation of the motor 104. The power supply module 112 is connected to the motor 104 for powering the motor 104 in order for normal operation of the power tool 100. The power supply module 112 is also connected to the motor driving circuit 110 for powering the motor driving circuit 110 to control the motor 104, for example providing an intermittent current or voltage to the motor 104 to produce a perceivable vibration or audible sound. The motor driving circuit 110 for example includes a microcontroller (not shown) to generate signals which are coupled to multiple switching elements like MOSFETs in the case that the motor 104 is a brushless motor. The user input device 114 for example a switch or a trigger is electrically connected to the motor driving circuit 110 so that it can be used to accept inputs from the user, and provide corresponding signals to the motor driving circuit 110. The above essential components of the power tool 100 are well-known in the art and thus will not be described in further details herein.

The sensor 116 is connected to the motor 104 for sensing fault conditions of the motor 104 or power tool 100. The sensor 116 is also connected to the motor driving circuit 110 to further transmit a sensed fault condition signal to the motor driving circuit 110. The fault conditions and operation parameters, in particular their variations over time, may be detected, measured, or otherwise obtained by the sensor 116. In other words, a various pattern of these status and parameters may be recorded which contains not only a single value but also a dynamic variation of these status and parameters as time passes by. Such operation parameters include but not limited to a working current of the motor 104, a voltage applied to the motor 104, a rotation speed of the motor 104 which is for example represented by revolution per minute (RPM) , a temperature of the motor 104, etc. The fault condition is determined when the sensed operation parameter exceeds a given threshold, or the operation parameter exceeds a given threshold over a given period of time, or the operation parameter changes dramatically over a given period of time. For example, if the sensed motor current exceed a value which over the 200%of a normal motor current, or it exceed a value which over the 200%of a normal motor current over 10 seconds, or it decreased dramatically within 1 second, then a fault condition will be determined and reported to the motor driving circuit. When such conditions occur, the motor driving circuit 110 will generate one or more audible sound and/or perceivable vibration to notice a user, meanwhile avoid and/or minimize any undesired rotation of the power tool 100, e.g., by shutting off or reducing power to the motor 104, by causing pulsing of the motor 104, and/or by actuating, a mechanical clutch. It is readily understood that other techniques for assessing the signal received from the sensor are within the scope of the present invention.

Referring Fig. 3, in order to sense the various parameters mentioned above, the sensor 116 includes at least one of a temperature detector 118 for detecting a temperature of the motor to generate a temperature signal; a current detector 120 for detecting current flowing through the motor to generate a current signal; a voltage detector 122 for detecting a voltage across the motor to generate a voltage signal; and a rotation speed detector 124 for detecting a rotation speed of the motor to generate a rotation speed signal. The motor driving circuit 122 receives at least one of the temperature, current, voltage and speed signals to determine a corresponding fault condition of the power tool 100 to provide the motor driving signal to the motor driving circuit 110. Moreover, in some embodiments, the sensor 116 can be configured to further include a user input detector 130 to detect a user’s input or behavior of control including but not limited to a selected working mode 132, and a position of the trigger 134 when it is actuated. The working mode can for example be selected by pressing a button or turning a knob (both not shown) configured on the housing 102 of the power tool 100, and may include a high speed rotation mode, a medium speed rotation mode, a low speed rotation mode, and other special working mode according to user’s requirements. The trigger can be a constant speed trigger or adjustable speed trigger. Once the working mode is selected or switched or the trigger is actuated, a signal will be provided by the sensor 116 for further execution.

Referring to Fig. 4, an exemplary method 200 for producing a notification to a user is illustrated. The method can be applied on the power tool illustrated in Figs 1-3, but it is not limited to as such, as other power tools may also adopt the same or similar method. In the method of Fig. 4, a first operation parameter, for example a motor current is selected as an operation parameter to be monitored to identify a fault condition. First, the method starts at Step 200, and then at Step 202 the motor driving circuit 110 determines whether the trigger switch is closed (as actuated by the user) to determine if the tool is operating. If the switch is not closed, then power is not being supplied to the motor 104 as indicated at Step 204. In this case, there is no need to monitor for fault conditions. Conversely, if the switch is closed, then power is being supplied to the motor as indicated at Step 206.

If the power is on, then at Step 208, the sensor monitors the current signal that indicates the amount of motor current. At Step 210, the amount of first operation parameter is compared to a given threshold amount. If the amount of first operation parameter is at or below the threshold, then the motor driving circuit determines that the motor operates normally. Therefore, the circuit will return to the start 200 of the algorithm. On the other hand, if the amount of first operation parameter exceeds the given threshold amount, then the motor driving circuit determines a fault condition, and produce a notification to a user at Step 230.

In a variation, at Step 210 the motor driving circuit may compare a mathematical function of the first operation parameter (e.g., a first or second derivative of the current signal such as a rate of change of first operation parameter) to a threshold value to make this determination. In yet another variation, the first operation parameter threshold values may vary depending on other tool conditions (e.g., a motor speed or the mode of the transmission) . Then, at Step 230, the motor driving circuit produces a notification to a user and/or initiates one or more protective operations to the power tool. At Step 230, the step of producing the notification to a user includes the actions of a) interrupting a power to the motor, b) reducing the power to the motor to a non-zero value, c) increasing the power to the motor, d) pulsing the motor, e) braking the motor, and f) actuating a clutch. These control actions aim to provide a notification in the form of an audible sound and/or a perceivable vibration via which the user is notified about the fault condition, and that the sound /vibration is easily distinguishable from the normal operation status of the power tool.

In a variation of the embodiment, at

Steps

210 and 230, for some operation parameters the condition of producing a notification to a user can be set out as an amount of operation parameter is lower or equal to a given threshold, i.e., if the amount of first operation parameter is at or larger than the threshold, then the motor driving circuit determines that the motor operates normally. Therefore, the circuit will return to the start 200 of the algorithm. On the other hand, if the amount of first operation parameter is smaller than the given threshold amount, then the motor driving circuit determines a fault condition, and produces a notification to a user at Step 230.

Referring to Fig. 5, a second exemplary method 300 for producing a notification to a user is illustrated. For the sake of brevity only differences in the method 300 as compared to that in Fig. 4 is described.

Steps

301, 302, 304, 306, 308, 310 and 330 are largely similar to their counterparts in Fig. 4, but any difference will be described below. In method 300, the different operation parameters involve an priority, for example a first operation parameter like a motor current is more of an essential operation parameter to determine the fault condition than a second operation parameter like a motor temperature, thus the first operation parameter will be sensed and monitored first as shown in the steps 300 to 310. If the monitored first operation parameter is over the given threshold value, at step 330, the motor driving circuit produces a notification to a user and/or initiates one or more protective operations to the power tool irrelevant of the amount of the second operation parameter.

On the other hand, if the first operation parameter is determined to be normal, then at Step 312, the sensor monitors a second operation parameter. At Step 312, the amount of second operation parameter is compared to a given threshold amount. If the amount of second operation parameter is at or below the threshold, then the motor driving circuit determines that the motor operates normally. Therefore, the motor driving circuit will return to the start 301 of the algorithm. On the other hand, if the second operation parameter exceeds the threshold, then the motor driving circuit determines that a fault condition of the second operation parameter has occurred. Similarly to that in the method of Fig. 4, at step 314 the microcontroller compares a mathematical function of the second operation parameter. Then, at step 330, the motor driving circuit produce a notification to a user and/or initiates one or more protective operations to the power tool. In method 300, the monitored operation parameters could be more than two, like motor current, temperature, voltage and rotation speed could be all taken into consideration with priorities.

Referring to Fig. 6, a third exemplary method 400 for producing a notification to a user is illustrated. For the sake of brevity only differences in the method 400 as compared to that in Fig. 4 is described.

Steps

401, 402, 404, 406, 408, 410 and 430 are largely similar to their counterparts in Fig. 5, but any difference will be described below. In method 400, the different operation parameters involve no priorities. In other words, if any monitored operation parameter exceeds its given threshold, the motor driving circuit produces a notification to a user and/or initiates one or more protective operations to the power tool. In method 400, the monitored operation parameters could be more than two, like the motor current, the temperature, the voltage and the rotation speed, which could be all taken into consideration without priorities, as shown by the arrow 440.

Referring to Fig. 7, a fourth exemplary method 500 for producing a notification to a user is illustrated. For the sake of brevity only differences in the method 500 as compared to that in Fig. 6 is described.

Steps

501, 502, 504, 506, 508, 510, 512, 514 and 540 are largely similar to their counterparts in Fig. 6, but any difference will be described below. In method 500, the different operation parameters involve no priorities. Meanwhile, the different fault condition will result a different notification to a user, as shown in

Steps

510 and 520. The different notifications include one or more of the followings: interrupting a power to the motor, reducing the power to the motor to a non-zero value, pulsing the motor, braking the motor, and actuating a clutch. For example, set the motor current as the first operation parameter, and the motor temperature as the second operation parameter. If the motor current exceeds the given current threshold, then the circuit interrupts a power to the motor. If the temperature exceed the given temperature threshold, then the circuit reduces the power to the motor to a non-zero value. Thus, the user will be noticed that there is not only one fault conditions detected in the power tool, and will take necessary actions thereof.

In an embodiment, the first notification and second notification can be produced alternatively, in order to generate audible sound and/or a perceivable vibration in turn to notify the user that there are two different fault conditions detected. In a variation, after the first notification and second notification are generated once, the power tool can be configured to generate notifications with a high priority only, for example, only the second notification indicating that the motor’s overheat is repeated. Thus, the user will be noticed and take necessary action to deal with this prioritized fault condition preferentially.

Particularly, in an embodiment, the motor is modulated by PWM or PFM, and the modulation of motor by PWM or PFM comprises at least one of the followings actions: a) applying a plurality of different driving modes to the motor; b) applying a plurality of different duty time of PWM or PFM; c) applying a plurality of different cycle time of PWM or PFM; d) intermittently stopping and restarting the motor; and e) applying a plurality of different motor currents. Then, the above mentioned actions can performed within a single motor driving cycle, or is performed when the motor enters from one driving cycle to another driving cycle in

Steps

510 and 520. By such actions, the notifications to a user is produced. Similar to the method 400, in method 500, the monitored operation parameter could be more than two, like the motor current, the temperature, the voltage and the rotation speed, which could be all taken into consideration without priorities, shown by the arrow 540.

Referring to Fig. 8, a fifth exemplary method 600 for producing a notification to a user is illustrated. For the sake of brevity only differences in the method 600 as compared to that in Fig. 5 is described.

Steps

601, 602, 604, 606, 608, 610 and 630 are largely similar to their counterparts in Fig. 5, but any difference will be described below. In method 600, two or more operation parameter are taken into consideration for producing a notification to a user, for example an instantaneous current as a first operation parameter which exceeds threshold might not be harmful to the power tool, but a current which exceeds threshold for a given period of time as a second operation parameter should be reported and noticed to the user. As shown in Steps 610 to 630, if the current is monitored exceeding the threshold, the sensor continues to monitor the period of time of the current exceed the threshold. If the period of time is longer than a given value, at Step 630, the motor driving circuit produce a notification to a user and/or initiates one or more protective operations to the power tool. If not, the circuit will return to the start of the algorithm the. Similar to other embodiments described above, in method 600, the monitored operation parameter could be selected from the motor current, the temperature, the voltage and the rotation speed, and might be more than two. Meanwhile, when two different operation parameters are selected, for example the current and temperature, a technical effect of preventing false notification or alarm could be achieved.

In a variation, a skilled person in art could understand that, the combination of monitoring and comparison of two or more parameters as stated in

Steps

608, 610, 620 and 622 can be combined as one sub-step, and comprised in

Step

208 and 210, 308 and 310, 408 and 410, or 508 and 510 in

exemplary method

200, 300, 400, and 500. In another words,

Steps

208 and 210, and other corresponding steps could be regarded as monitoring and comparison of two or more parameters, followed by necessary actions as illustrated in method 600, which does not go beyond the scope of present application.

In a variation, after the Step 630, the power tool could be shut down directly for the user to further check or determine the reason of the fault condition. Alternatively, the motor driving circuit is further configured to audit the fault condition, if the fault condition eliminates, for example the current is lower than the given threshold for a period of time, and the motor driving circuit is configured to generate a signal to re-operate the power tool.

Referring to Fig. 9, a sixth exemplary method 700 for producing a notification to a user is illustrated. For the sake of brevity only differences in the method 700 as compared to that in Fig. 5 is described.

Steps

701, 702, 704, 706, 708, 710 and 730 are largely similar to their counterparts in Fig. 5, but any difference will be described below. In method 700, when a fault condition is firstly detected, i.e., a monitored operation parameter lower or exceed or equal to an threshold, as shown in

Step

708 and 710, the power tool will be configured to regulate an output of the power tool at first, for example, by lowering the output frequency, reducing to motor current, switching to a lower speed operation mode, etc. The regulated output aims to eliminate the detected fault condition without a user intervention, and configure the power tool to be operated in a lower energy consumption mode. After regulating the output at Step 712, as shown in

Steps

720 and 722, the operation parameter is still be monitored, and if the operation parameter being monitored is still lower or exceeded or equal to the threshold, then at Step 730, the motor driving circuit produces a notification to a user and/or initiates one or more protective operations to the power tool. If not, the circuit will return to the start of the algorithm, or return to Step 708 to continue the monitoring. Similar to other embodiments described above, in method 700, the monitored operation parameter could be selected from the motor current, the temperature, the voltage and the rotation speed, and might contain more than one of these parameters. In some embodiments, the operation parameter monitored in

Step

708 and 722 may be the same operation parameter, for example the motor current, but in other embodiments they might be different operation parameters, for example a motor current and a motor temperature.

Other than the fault conditions described in the above exemplary methods, the fault conditions may also include the cases as listed below. Case 1: motor current meets the setting value and setting time. Case 2: power tool voltage meets the setting value and setting time. Case 3: motor speed meets the setting value and setting time. Case 4: MOSFET temperature or motor temperature meets the setting value and setting time. Case 5: PWM duty meets setting value and setting time. PWM duty range can be set from 0%to 100%. Case 6: two or more cases of the above cases met at the same time. If such cases are detected, the motor driving circuit will also produce a notification to a user and/or initiates one or more protective operations to the power tool.

In an embodiment, the motor is modulated by PWM or PFM to produce a notification to a user. PWM or PFM is a method of reducing the average power delivered by an electrical signal, by effectively chopping it up into discrete parts. The average value of voltage (and current) fed to the load is controlled by turning the switch between supply and load on and off at a fast rate. Normally, in PWM, the cycle is fixed, the output average power is modulated by the time of duration of high level signal or duty cycle. On the other hand, in PFM, the time of duration of high level signal is fixed, the output average power is modulated by the different time duration of the cycle. For the convenience of explanation, most of the modulation methods in this article use PWM as an example. However, those skilled in the art can understand that the same or similar effects can be achieved if PFM is used for modulation.

According to one example, as shown in Fig. 10, the motor driving circuit 110 sets the duty rate of the pulse width of the PWM signal corresponding to a control signal output from the user input device 114 (for example a trigger) (hereinafter, referred to as “PWM duty” ) in accordance with the trigger pressed distance by of the trigger. Meanwhile, on the other hand, the motor driving circuit modulate the motor by PWM or PFM. In a variation, a constant speed trigger could also be applied to control an output of the power tool. For the constant speed trigger, the output is not modulated by the extent of the user pressing the trigger. When the trigger is pressed, the PWM duty will be set as a constant level.

Referring to Fig. 11, according to another example the output power of the power tool is represented by the PWM which modulates the motor. The PWM waveform is stable and constant in period 1 which shows the power tool is working normally. The PWM waveforms includes several waveforms with different PWM duties in period 2 that change dramatically, which shows that the motor driving signal is modulated by the motor driving circuit to produce a notification to user about the detected fault conditions. The PWM duties in period 2 may contain a single repeated waveform which produce a notification to user that there is one fault condition detected, or several waveforms in a cycle period, in order to notify the user that there are multiple fault conditions detected. The modulations by PWM includes a) applying a plurality of different driving modes to the motor; b) applying a plurality of different duty time of PWM or PFM; c) applying a plurality of different cycle time of PWM or PFM; d) intermittently stopping and restarting the motor; and e) applying a plurality of different motor currents. Such actions a) to e) above is performed within a single motor driving cycle, or is performed when the motor enters from one driving cycle to another driving cycle.

Referring to Fig. 12A to 12H, the PWM waveforms in period 2 of Fig. 11 includes one or more of a) low duty cycle PWM as shown in Fig. 12A; b) middle duty cycle PWM as shown in Fig. 12B; c) high duty cycle PWM as shown in Fig. 12C; d) a combination of increasing duty cycle PWM and decreasing duty cycle PWM as shown in Fig. 12D; e) mixed different duty cycles PWM repeated periodically as shown in Fig. 12E to 12H.

In the case of a low duty cycle PWM as shown in Fig. 12A, the output of motor operates slowly but powerfully, thus a low frequency perceivable vibration is produced to notice the user that a fault condition is detected. If the cycle time is long enough, the motor will operate in the manner that it stops for a while and then restarts. Such abnormal behavior is also noticeable to the user that the power tool has a fault condition.

In the case of a middle duty cycle PWM shown in Fig. 12B or c) high duty cycle PWM shown in Fig. 12C, the constant middle and high duty cycle PWM can be combined and outputted periodically, thus a perceivable vibration switched between a middle or high frequency is produced to notify the user that one or more fault conditions are detected.

In the case of a combination of increasing duty cycle PWM and decreasing duty cycle PWM is used as shown in Fig. 12D, where the output of motor varies from a low rotation speed to a high rotation speed and then back to low rotation speed in a circulation. Thus a varying frequency perceivable vibration is produced to notify the user that a fault condition is detected.

In the case of mixed PWM signals with different duty cycles are repeated periodically as shown in Fig. 12E, where the output of motor varies from a low rotation speed, then stops and then backs to a low rotation speed in a circulation. Thus a varying frequency perceivable vibration is produced to notify the user that a fault condition is detected. Meanwhile, the time period 1 and time period 2 could be configured to correspond to different fault condition, for example in time period 1, the motor is configured to report an current fault condition, and in time period 2, the motor is configure to report an temperature fault condition. Therefore, the user will be notified that the power tool is operating abnormally. In a variation, the repeated time period 1 and time period 2 could be configured to correspond to one fault condition, such as in time period 1, the motor is configured to operate constantly, but in time period 2, the motor’s operation is interrupted. By repeating such behaviors, the fault condition is noticeable to the user.

In the case of mixed PWM signals with different duty cycles are repeated periodically as shown in Fig. 12F, where the output of motor varies from a low rotation speed for a period of time, then a high rotation speed for a period of time to low rotation speed in a circulation. Thus a varying frequency perceivable vibration is produced to notify the user that a fault condition is detected. Similar to Fig. 12E the time period 1 and time period 2 could be configured to correspond to different fault conditions.

In the case of mixed PWM signals with different duty cycles are repeated periodically as shown in Fig. 12G and 12H, where the output of motor operates from different rotation speeds in a short or given period of time. Thus a varying frequency perceivable vibrations are produced to notice the user that a fault condition is detected by the user.

In an embodiment, to prevent to motor from working in an abnormal working state for a long time (during the fault condition is determined and the period of producing the notification to user) , after the fault condition is determined, a clutch in the power tool is actuated to disconnect the motor to an output shaft. In such case, the motor is running at idling, which also provides an abnormal audible sound to produce a notification to a user.

While the invention has been illustrated and described in detail in the drawings and foregoing descript ion, the same is to be considered as illustrative and not restrictive in character, it being understood that only e xemplary embodiments have been shown and described and do not limit the scope of the invention in any ma nner. It can be appreciated that any of the features described herein may be used with any embodiment. The il lustrative embodiments are not exclusive of each other or of other embodiments not recited herein. According ly, the invention also provides embodiments that comprise combinations of one or more of the illustrative em bodiments described above. Modifications and variations of the invention as herein set forth can be made wit hout departing from the spirit and scope thereof, and, therefore, only such limitations should be imposed as ar e indicated by the appended claims.

In addition to using the vibration and sound of the motor to produce the fault alarm, some embodiments of the present invention also use a high-frequency whistle of the battery or a special design of the air outlet of the power tool to generate a notification, which can also achieve intuitive and effective technical effects of attracting the user's attention better.

Claims

A power tool adapted to produce a notification to a user, comprising:

a sensor configured to sense a fault condition of the power tool;

a motor driving circuit connected to the sensor, and configured to provide a motor driving signal based on the fault condition of the power tool; and

a motor connected to the motor driving circuit and adapted to be driven by the motor driving signal from the motor driving circuit to produce the notification;

wherein the notification is in the form of an audible sound and/or a perceivable vibration via which the user is notified about the fault condition.
The power tool of claim 1, wherein the motor is adapted to be driven at different powers and/or frequencies under a modulation of the motor driving signal.
The power tool of claim 2, wherein the modulation of the motor driving signal includes one or more of the followings: interrupting a power to the motor, reducing the power to the motor to a non-zero value, increasing the power to the motor, pulsing the motor, braking the motor, and actuating a clutch.
The power tool of claim 2, wherein the motor is adapted to be driven using PWM (Pulse Width Modulation) or PFM (Pulse FrequencyModulation) to produce the notification.
The power tool of claim 4, wherein the modulation of motor by PWM or PFM comprises at least one of the followings actions:

a) applying a plurality of different driving modes to the motor;

b) applying a plurality of different duty time of PWM or PFM;

c) applying a plurality of different cycle time of PWM or PFM;

d) intermittently stopping and restarting the motor; and

e) applying a plurality of different motor currents.
The power tool of claim 5, wherein each one of the actions a) to e) above is performed within a single motor driving cycle, or is performed when the motor enters from one driving cycle to another driving cycle.
The power tool of claim 5, wherein the modulation comprises at least two modes of different powers or frequencies of motor, and the powers or frequencies switch periodically.
The power tool of claim 1, wherein the sensor comprises at least one of:

a temperature detector for detecting a temperature of the motor to generate a temperature signal;

a current detector for detecting current flowing through the motor to generate a current signal;

a voltage detector for detecting a voltage across the motor to generate a voltage signal; and

a rotation speed detector for detecting a rotation speed of the motor to generate a rotation speed signal, and

a user input detector for detecting for detecting a selected working mode of the power tool and a position of a trigger when actuated to generate a input signal,

wherein, the motor driving circuit receives at least one of the temperature, current, voltage, rotation speed and input signals to determine a corresponding fault condition of the power tool to provide the motor driving signal.
The power tool of claim 8, wherein the fault condition is reported if at least one of the temperature, current, voltage, rotation speed signal exceeds a given threshold, or exceeds a given threshold over a given period of time, or changes dramatically over a given period of time.
The power tool of claim 9, wherein the motor driving circuit is further configured to audit the fault condition, if the fault condition eliminates, the motor driving circuit is configured to generate a signal to re-operate the power tool.
A method of producing a notification to a user, comprising:

a) sensing a fault condition of the power tool by a sensor;

b) providing a motor driving signal based on the fault condition of the power tool by a motor driving circuit connected to the sensor ; and

c) producing the notification by the motor connected to the motor driving circuit and adapted to be driven by the motor driving signal from the motor driving circuit;

wherein the notification is in the form of an audible sound and/or a perceivable vibration via which the user is notified about the fault condition.
The method of claim 11, wherein the motor is adapted to be driven at different powers and/or frequencies under a modulation of the motor driving signal.
The method of claim 12, wherein the modulation of the motor driving signal includes one or more of the followings: interrupting a power to the motor, reducing the power to the motor to a non-zero value, increasing the power to the motor, pulsing the motor, braking the motor, and actuating a clutch.
The method of claim 12, wherein the notification is produced by the motor which is adapted to be driven using PWM or PFM.
The method of claim 14, wherein the modulation of motor by PWM or PFM comprises at least one of the followings actions,

a) applying a plurality of different driving modes to the motor;

b) applying a plurality of different duty time of PWM or PFM;

c) applying a plurality of different cycle time of PWM or PFM;

d) intermittently stopping and restarting the motor; and

e) applying a plurality of different motor currents.
The method of claim 15, wherein each one of the actions a) to e) above is performed within a single motor driving cycle, or is performed when the motor enters from one driving cycle to another driving cycle.
The method of claim 15, wherein the modulation comprises at least two modes of different powers or frequencies of motor, and the powers or frequencies switch periodically.
The method of claim 11, wherein one or more operation parameters of the power tool are monitored by the sensor to generate one or more detected signals to determine the fault condition of the power tool, the detected signal comprises at least one of:

a temperature signal, detected by a temperature detector for detecting a temperature of the motor;

a current signal, detected by a current detector for detecting current flowing through the motor;

a voltage signal, detected by a voltage detector for detecting a voltage across the motor;

a rotation speed signal, detected by a rotation speed detector for detecting a rotation speed of the motor, and

a user input detector for detecting for detecting a selected working mode of the power tool and a position of a trigger when actuated to generate a input signal,

wherein, the motor driving circuit receives at least one of the temperature, current, voltage, rotation speed and input signals to determine a corresponding fault condition of the power tool to provide the motor driving signal.
The method of claim 18, wherein the fault condition is reported if any of the temperature, current, voltage, rotation speed signal exceeds a given threshold, or exceeds a given threshold over a given period of time, or changes dramatically over a given period of time.
The method of claim 19, further comprising a step of auditing the fault condition by the motor driving circuit, wherein if the fault condition eliminates, the power tool is configured to re-operate by modulation of a signal generated by the motor driving circuit.