GB2427041A - Torque control device for electrical tools - Google Patents

Torque control device for electrical tools Download PDF

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Publication number
GB2427041A
GB2427041A GB0609636A GB0609636A GB2427041A GB 2427041 A GB2427041 A GB 2427041A GB 0609636 A GB0609636 A GB 0609636A GB 0609636 A GB0609636 A GB 0609636A GB 2427041 A GB2427041 A GB 2427041A
Authority
GB
United Kingdom
Prior art keywords
circuit
processor
voltage
torque
motor
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Granted
Application number
GB0609636A
Other versions
GB2427041B (en
GB0609636D0 (en
Inventor
Fu-Hsiang Chung
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Techway Industrial Co Ltd
Original Assignee
Techway Industrial Co Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Techway Industrial Co Ltd filed Critical Techway Industrial Co Ltd
Publication of GB0609636D0 publication Critical patent/GB0609636D0/en
Publication of GB2427041A publication Critical patent/GB2427041A/en
Application granted granted Critical
Publication of GB2427041B publication Critical patent/GB2427041B/en
Active legal-status Critical Current
Anticipated expiration legal-status Critical

Links

Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B25—HAND TOOLS; PORTABLE POWER-DRIVEN TOOLS; MANIPULATORS
    • B25B—TOOLS OR BENCH DEVICES NOT OTHERWISE PROVIDED FOR, FOR FASTENING, CONNECTING, DISENGAGING OR HOLDING
    • B25B23/00—Details of, or accessories for, spanners, wrenches, screwdrivers
    • B25B23/14—Arrangement of torque limiters or torque indicators in wrenches or screwdrivers
    • B25B23/147—Arrangement of torque limiters or torque indicators in wrenches or screwdrivers specially adapted for electrically operated wrenches or screwdrivers
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
    • B23P—METAL-WORKING NOT OTHERWISE PROVIDED FOR; COMBINED OPERATIONS; UNIVERSAL MACHINE TOOLS
    • B23P19/00—Machines for simply fitting together or separating metal parts or objects, or metal and non-metal parts, whether or not involving some deformation; Tools or devices therefor so far as not provided for in other classes
    • B23P19/04—Machines for simply fitting together or separating metal parts or objects, or metal and non-metal parts, whether or not involving some deformation; Tools or devices therefor so far as not provided for in other classes for assembling or disassembling parts
    • B23P19/06—Screw or nut setting or loosening machines
    • B23P19/065—Arrangements for torque limiters or torque indicators in screw or nut setting machines
    • B23P19/066—Arrangements for torque limiters or torque indicators in screw or nut setting machines by electrical means
    • G—PHYSICS
    • G05—CONTROLLING; REGULATING
    • G05D—SYSTEMS FOR CONTROLLING OR REGULATING NON-ELECTRIC VARIABLES
    • G05D17/00—Control of torque; Control of mechanical power
    • G05D17/02—Control of torque; Control of mechanical power characterised by the use of electric means
    • 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 torque control device for an electrical tool has a switching circuit (10), a voltage detecting circuit (30), a torque detecting circuit (40) and a processor (20). The switching circuit (10) connects between a motor of the electrical tool and a DC voltage source. The voltage detecting circuit (30) detects voltage variation of the motor. The torque detecting circuit (40) based on the detected voltage or current variation data outputs an actual torque value of the motor. The processor (20) may compare the actual torque value with a default value to determine whether actual torque is greater than the default. If so, the switching circuit (10) may be turned off by the processor (20) to prevent the motor from being damaged. A high voltage protecting circuit (50) and a low voltage protecting circuit (60) are also provided.

Description

TORQUE CONTROL DEVICE FOR ELECTRICAL TOOLS
1. Field of the invention
The present invention relates to a torque control device, and more particularly to a torque control device for electrical tools, where the control device can automatically interrupt a power supply of the electrical tools if a detected actual torque is greater than a default torque value.
2. Description of Related Art
Electrical tools commonly have an electrical motor to drive a tool head thus assisting an operator to easily accomplish operations such as screwing or drilling. Each kind of tool head can sustain a particular torque corresponding to a target object to be driven. Therefore, the torque generated by the electrical tools is required to be adjustable for accommodating different target objects. If the torque exceeds a tolerable range that the tool head can sustain, this tool head will be temporarily disengaged from the motor so as to avoid possible damage to the tool head and the motor.
The default torque setting can be accomplished by mechanically varying the compressing extent of a spring installed in the electrical tools. The tool head is driven by the motor as long as the torque is within the default value. However, using the spring to mechanically set the torque and obtaining a precise default value are both very difficult. Further, even when the tool head has been temporarily disengaged under the motor, the motor in the idling status continuously consumes power.
Therefore, the invention provides a torque control device for electrical tools to mitigate or obviate the aforementioned problem.
An objective of the present invention is to provide a torque control device for electrical tools, wherein a default torque can be precisely set. If the actual torque value of a motor of the electrical tools is greater than the default value, the power supply to the motor can be interrupted to protect the motor.
To accomplish the objective, an embodiment of the torque control device provides: a switching circuit being connected between the motor and the DC voltage source; a processor with an output terminal being connected to the switching circuit to turn on or turn off the switching circuit; a voltage detecting circuit having an input terminal connected between the motor and the DC voltage source to detect voltage variation data of the motor; a torque detecting circuit connected between the voltage detecting circuit and the processor to produce a motor torque value to be output to the processor based on the voltage variation data; a torque setting unit being connected to the processor to provide a default torque value to the processor; a high voltage protecting circuit connected between the voltage detecting circuit and the processor and comprising a second operating amplifier having two input terminals being connected respectively to the voltage detecting circuit and a high reference voltage; and an output terminal being connected to the processor; a low voltage protecting circuit connected between the voltage detecting circuit and the processor and comprising an operating amplifier having two input terminals being connected respectively to the voltage detecting circuit and a low reference voltage; and an output terminal connected to the processor; and a display connected to the processor to show the default torque.
To accomplish the objective, another embodiment of the torque control device provides: a switching circuit being connected between the motor and the DC voltage source and comprising a driving transistor having a base, a collector and an emitter; and a switching transistor having a gate connected to the collector, and a source and a drain connected respectively to the motor and the DC voltage source; a processor with an output terminal being connected to the base of the driving transistor of the switching circuit to turn on or turn off the switching circuit; a high voltage protecting circuit being connected to the processor; a voltage detecting circuit having a voltage dividing circuit formed by a first resistor and a second resistor connected in series, wherein a first terminal of the first resistor is connected to the DC voltage source and the switching circuit; and a second terminal of the first resistor is connecting to the second resistor is connected to the high voltage protecting circuit; a torque detecting circuit being connected between the voltage detecting circuit and the processor to produce a motor torque value to be output to the processor based on the voltage variation data; and a torque setting unit being connected to the processor to provide a default torque value to the processor and comprising a first RC circuit and a first operating amplifier as a buffer.
[N THE DRAWINGS Fig. 1 is a block diagram of a torque control device in accordance with the present invention; Fig. 2 is a circuit diagram of the torque control device according to a first embodiment of the present invention; and Fig. 3 is a circuit diagram of the torque control device according to a second embodiment of the present invention.
With reference to Fig. 1, a torque control device for electrical tools comprises a switching circuit (10), a processor (20), a voltage detecting circuit (30), a torque detecting circuit (40), a high voltage protecting circuit (50), a low voltage protecting circuit (60), a torque setting unit (70) and a display (80).
The switching circuit (10) is connected between a motor and a DC voltage source, wherein the DC voltage source can be a battery.
The processor (20) has a first output terminal connected to the switching circuit (10) so as to control its onloff statuses.
The voltage detecting circuit (30) has an input terminal connected between the DC voltage source and the motor, whereby voltage or current variations of the motor can be detected.
The torque detecting circuit (40) is connected between the voltage detecting circuit (30) and the processor (20). Based on voltage and/or current variation data of the motor or their varying frequency within a time unit, the torque detecting circuit (40) can based on the detected data to generate a torque value of the motor and supplies the torque value to the processor (20).
The high voltage protecting circuit (50) connects between the voltage detecting circuit (30) and the processor (20). The high voltage protecting circuit (50) compares the detected voltage value from the voltage detecting circuit (30) with a high reference voltage. If the detected voltage is greater than the high reference voltage, the high voltage protecting circuit (50) outputs a signal to the processor (20) so that the switching circuit (10) can be turned off upon reception of the command of the processor.
The low voltage protecting circuit (60) is connected between the voltage detecting circuit (30) and the processor (20). The low voltage protecting circuit (60) compares the detected voltage value from the voltage detecting circuit (30) with a low reference voltage. If the detected voltage is smaller than the low reference voltage, the low voltage protecting circuit (50) outputs a signal to the processor (20) so that the switching circuit (10) can be turned off upon reception of the command output from the processor (20).
The torque setting unit (70) is connected to the processor (20). An operator can set a default torque in the processor (20) through the torque setting unit (70).
The display (80) is connected to an output terminal of the processor (20) for displaying the default torque level set by the operator.
With reference to Fig. 2, the switching circuit (10) comprises a driving transistor (11) and a switching transistor (12). The driving transistor (11) comprises a bipolar juncti on transistor (BJT) with a base, a collector and an emitter. The switching transistor (12) is a MOSFET with a gate, a source and a drain. The driving transistor (11) provides its base connecting to the processor (20) through a resistor, and its collector is connected to the gate of the switching transistor (12). The drain and source of the switching transistor (12) are respectively connected to the DC voltage source and the motor. When the processor (20) output a signal with a high voltage level to activate the driving transistor (11), the switching transistor (12) is subsequently turned on which allows the DC voltage source provides power to the motor. Otherwise, when the driving transistor (11) is deactivated, the switching transistor (12) is accordingly turned off, whereby the power supply to the motor can be terminated.
The voltage detecting circuit (30) is composed of a voltage dividing circuit with two resistors Ri, R2 connected in series. One terminal of the resistor Ri is connected to the DC voltage source and the switching circuit (10). The other terminal of the resistor RI to which the resistor R2 is connected is coupled to the high voltage protecting circuit (50).
The torque detecting circuit (40) comprises an operation amplifier U2B and an RC circuit formed by a resistor R3 and a capacitor Cl. The operation amplifier is configured as a buffer, wherein the negative terminal and the output terminal of the operation amplifier are connected together to form a negative feedback loop.
The high voltage protecting circuit (50) is formed by an operation amplifier U1B that serves as a comparator. The comparator has a positive input terminal and a negative input terminal which are respectively coupled to the high reference voltage and the voltage detecting circuit (30). If the output voltage of the voltage detecting circuit (30) is greater than the high reference voltage, the comparator outputs a signal with a low level to notify the processor (20). The processor (20) can subsequently turn off the switching circuit (10) to avoid possible damage.
The low voltage protecting circuit (60) is also formed by an operation amplifier U3B serving as a comparator. The comparator has a positive input terminal and a negative input terminal which are respectively coupled to the voltage detecting circuit (30) and a low reference voltage. If the output voltage of the voltage detecting circuit (30) is smaller than the low reference voltage, the comparator outputs a signal with a low level to notify the processor (20). The processor (20) can subsequently turn off the switching circuit (10).
The torque setting unit (70) comprises a switch (71) having multiple nodes and a torque setting circuit (72). The torque setting circuit (72) is formed by multiple resistors. When one node in the switch (71) is selected, a respective input terminal of the processor (20) corresponding to the node represents a voltage. The processor (20) according to the represented voltage determines the torque value.
The display (80) is preferably a seven-segment display element with multiple input terminals connected to the processor (20).
With reference to Fig. 3, the second embodiment is substantially similar to the first one of Fig. 2. The modification in this embodiment aims at the torque setting unit (70'). The torque setting unit (70') includes a rheostat (73) and a torque setting circuit (72'), wherein the torque setting circuit (72') consists of a resistor R6, a capacitor C2 and an operation amplifier U4B. The operation amplifier U4B is configured to form a buffer.
The voltage detecting circuit accompanying the torque detecting circuit can acquire the instant torque value of a motor according to the voltage andlor current variation data between the motor and the DC voltage source, or the varying frequency of the voltage andlor current in a time unit. The processor further compares the torque value with a default torque to determine whether the motor should be turned off. If the torque value of the motor is greater than the default value, the power supply to the motor is interrupted. Thus, the default value can be precisely set by a torque setting unit.

Claims (8)

  1. CLAIMS: 1. A torque control device for an electrical tool having a motor
    powered by a DC voltage source, the torque control device comprising: a switching circuit (10) being connected between the motor and the DC voltage source; a processor (20) with an output terminal being connected to the switching circuit (10) to turn on or turn off the switching circuit (10); a voltage detecting circuit (30) having an input terminal connected between the motor and the DC voltage source to detect voltage variation data of the motor; a torque detecting circuit (40) connected between the voltage detecting circuit (30) and the processor (20) to produce a motor torque value to be output to the processor (20) based on the voltage variation data; a torque setting unit (70) being connected to the processor (20) to provide a default torque value to the processor (20); a high voltage protecting circuit (50) connected between the voltage detecting circuit (30) and the processor (20) and comprising a second operating amplifier (U 1 B) having two input terminals being connected respectively to the voltage detecting circuit (30) and a high reference voltage; and an output terminal being connected to the processor (20); a low voltage protecting circuit (60) connected between the voltage detecting circuit (30) and the processor (20) and comprising an operating amplifier (U3B) having two input terminals being connected respectively to the voltage detecting circuit (30) and a low reference voltage; and an output terminal connected to the processor (20); and a display (80) connected to the processor (20) to show the default torque.
  2. 2. The torque control device as claimed in claim 1, wherein the switching circuit (10) comprises: a driving transistor (11) having a base connected to the processor (20) through a resistor, a collector and an emitter; and a switching transistor (12) having a gate connected to the collector, a source and a drain with the source and drain connected respectively to the motor and the DC voltage source; the voltage detecting circuit (30) comprises a voltage dividing circuit formed by a first resistor (RI) and a second resistor (R2) connected in series; wherein a first terminal of the first resistor (Rl) is connected to the DC voltage source and the switching circuit (10), and a second terminal of the first resistor (Ri) connecting the second resistor (R2) is coupled to the high voltage protecting circuit (50); and the torque detecting unit (40) comprises a first RC circuit (R3, Cl) and a first operating amplifier (U2B) as a buffer.
  3. 3. The torque control device as claimed in one of claims I and 2, the torque setting unit (70) comprising: a switch (71) having multiple nodes; and a torque setting circuit (72) formed by multiple resistors, wherein each resistor is connected to a respective node of the switch (71) and a respective input terminal of the processor (20).
  4. 4. The torque control device as claimed in one of claims I and 2, the torque setting unit (70') comprising: a rheostat (73); and a torque setting circuit (72') formed by an RC circuit (R6, C2) and a fourth operation amplifier (U4B), wherein the fourth operation amplifier (U4B) has an input terminal connected to the RC circuit (R6,C2) and has an output terminal connected to the processor (20).
  5. 5. A torque control device for an electrical tool having a motor powered by a DC voltage source, the torque control device comprising: a switching circuit (10) being connected between the motor and the DC voltage source and comprising a driving transistor (11) having a base, a collector and an emitter; and a switching transistor (12) having a gate connected to the collector, and a source and a drain connected respectively to the motor and the DC voltage source; a processor (20) with an output terminal being connected to the base of the driving transistor (11) of the switching circuit (10) to turn on or turn off the switching circuit (10); a high voltage protecting circuit (50) being connected to the processor (20); a voltage detecting circuit (30) having a voltage dividing circuit formed by a first resistor (Ri) and a second resistor (R2) connected in series, wherein a first terminal of the first resistor (Ri) is connected to the DC voltage source and the switching circuit (10); and a second terminal of the first resistor (RI) is connecting to the second resistor (R2) is connected to the high voltage protecting circuit (50); a torque detecting circuit (40) being connected between the voltage detecting circuit (30) and the processor (20) to produce a motor torque value to be output to the processor (20) based on the voltage variation data; and a torque setting unit (70) being connected to the processor (20) to provide a default torque value to the processor (20) and comprising a first RC circuit (72') and a first operating amplifier (U4B) as a buffer.
  6. 6. The torque control device as claimed in claim 5, the high voltage protecting circuit (50) comprising: a second operating amplifier (U1B) having two input terminals respectively connected to the voltage detecting circuit (30) and a high reference voltage; and an output terminal connected to the processor (20); with the torque control device further comprising: a low voltage protecting circuit (60) being connected between the voltage detecting circuit (30) and the processor (20) and comprising a third operating amplifier (U3B) having two input terminals connected respectively to the voltage detecting circuit (30) and a low reference voltage; and an output terminal connected to the processor (20); and a display (80) connected to the processor (20) to show the default torque.
  7. 7. The torque control device as claimed in one of claims 5 and 6, the torque setting unit (70) comprising: a switch (71) having multiple nodes; and a torque setting circuit (72) formed by multiple resistors, wherein each resistor is connected to a respective node of the switch (71) and a respective input terminal of the processor (20).
  8. 8. The torque control device as claimed in one of claims 5 and 6, the torque setting unit (70') comprising: a rheostat (73); and a torque setting circuit (72) formed by an RC circuit (R6, C2) and a fourth operating amplifier (U4B), wherein the fourth operating amplifier (U4B) has an input terminal connected to the RC circuit (R6, C2); and an output terminal connected to the processor (20).
GB0609636A 2005-06-06 2006-05-16 Torque control device for electrical tools Active GB2427041B (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
TW094118561A TWI262112B (en) 2005-06-06 2005-06-06 Torque control device for electrical tools

Publications (3)

Publication Number Publication Date
GB0609636D0 GB0609636D0 (en) 2006-06-28
GB2427041A true GB2427041A (en) 2006-12-13
GB2427041B GB2427041B (en) 2007-05-30

Family

ID=37440179

Family Applications (1)

Application Number Title Priority Date Filing Date
GB0609636A Active GB2427041B (en) 2005-06-06 2006-05-16 Torque control device for electrical tools

Country Status (5)

Country Link
KR (1) KR100719198B1 (en)
DE (1) DE102006023966A1 (en)
FR (1) FR2889895B1 (en)
GB (1) GB2427041B (en)
TW (1) TWI262112B (en)

Families Citing this family (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
KR101549864B1 (en) 2009-09-29 2015-09-03 엘지전자 주식회사 Apparatus and method for controlling single-phase induction motor
TWI516342B (en) * 2013-10-04 2016-01-11 Tranmax Machinery Co Ltd Hydraulic power tool with speed and speed function
DE102014108398B4 (en) * 2014-06-13 2016-12-08 Techway Industrial Co., Ltd. Electric rivet nut tool

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2269025A (en) * 1992-07-24 1994-01-26 Delco Chassis Overseas Corp Torque controller for electrical tool.
GB2271197A (en) * 1992-08-28 1994-04-06 Nissan Motor Impact type clamping apparatus

Family Cites Families (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
KR940003002B1 (en) * 1991-12-30 1994-04-09 금성기전 주식회사 Over current relay
KR0157865B1 (en) * 1993-11-29 1999-03-20 김회수 Overload test apparatus
KR20000012975A (en) * 1998-08-03 2000-03-06 김세광 Device of cutting load indication and overload cut-off for electromotive machine tool

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2269025A (en) * 1992-07-24 1994-01-26 Delco Chassis Overseas Corp Torque controller for electrical tool.
GB2271197A (en) * 1992-08-28 1994-04-06 Nissan Motor Impact type clamping apparatus

Also Published As

Publication number Publication date
TW200642788A (en) 2006-12-16
KR20060127793A (en) 2006-12-13
KR100719198B1 (en) 2007-05-16
GB2427041B (en) 2007-05-30
FR2889895A1 (en) 2007-02-23
TWI262112B (en) 2006-09-21
GB0609636D0 (en) 2006-06-28
DE102006023966A1 (en) 2006-12-14
FR2889895B1 (en) 2011-04-08

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