GB1590494A - Creación de Inventos y Patentes con Inteligencia Artificial

GB1590494A – Electrical drive systems for sewing machines
– Google Patents

GB1590494A – Electrical drive systems for sewing machines
– Google Patents
Electrical drive systems for sewing machines

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Publication number
GB1590494A

GB1590494A
GB5860/78A
GB586078A
GB1590494A
GB 1590494 A
GB1590494 A
GB 1590494A
GB 5860/78 A
GB5860/78 A
GB 5860/78A
GB 586078 A
GB586078 A
GB 586078A
GB 1590494 A
GB1590494 A
GB 1590494A
Authority
GB
United Kingdom
Prior art keywords
speed
output
circuit
motor
signal
Prior art date
1977-02-18
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.)

Expired

Application number
GB5860/78A
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.)

Brother Industries Ltd

Original Assignee
Brother Industries 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.)
1977-02-18
Filing date
1978-02-14
Publication date
1981-06-03

1978-02-14
Application filed by Brother Industries Ltd
filed
Critical
Brother Industries Ltd

1981-06-03
Publication of GB1590494A
publication
Critical
patent/GB1590494A/en

Status
Expired
legal-status
Critical
Current

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Classifications

D—TEXTILES; PAPER

D05—SEWING; EMBROIDERING; TUFTING

D05B—SEWING

D05B69/00—Driving-gear; Control devices

D05B69/22—Devices for stopping drive when sewing tools have reached a predetermined position

D05B69/26—Devices for stopping drive when sewing tools have reached a predetermined position with automatic means to reduce speed of drive, e.g. in one or more steps

Description

PATENT SPECIFICATION
( 11) et ( 215 Application No 5860/78 ( 22) Filed 14 Feb 1978 Cl ( 31) Convention Application No.
c 52/017432 ( 32) Filed 18 Feb1977 in ( 33) Japan (JP) ( 44) Complete Specification published 3 June 1981 ( 51) INT CLU HO 2 P 3/16 ( 52) Index at acceptance G 3 N 282 B 288 X DA ( 54) IMPROVEMENTS IN ELECTRICAL DRIVE SYSTEMS FOR SEWING MACHINES ( 71) We, BROTHER Ko GYO KABUSHIKI KAISHA, a Corporation organised under the Laws of Japan of 35, 9-chome, Horita-dori, Mizuho-ku, Nagoya-shi, Aichi-ken, Japan, do hereby declare the invention for which we pray that a patent may be granted to us and the method by which it is to be performed, to be particularly described in and by the following statement:
This invention relates to electrical drive systems for sewing machines.
Controlling arrangements for the electrical drive systems of certain sewing machines, chiefly industrial sewing machines, are designed for the purpose of halting or stopping the machine and its needle at a certain preset position.
With regard to this sort of controlling arrangement, a conventionally practised method is to apply dynamic braking to a motor in response to a decelerating command signal for changing from high speed running to low speed running, and to apply again, after having kept the motor running at the low speed for a while, the dynamic braking upon receiving a stopping command signal, or to employ an electromechanical braking means such as an electromagnetic brake.
In this conventional method, it takes a considerable length of time before the motor is completely stopped after a decelerating command signal has been produced, which is not a negligible factor with regard to efficient operation of industrial sewing machines and the like.
In studying reasons for the delay, it was found that the period of time required for changing the speed from high to low after a decelerating command signal has been produced was the longest of all, i e, the principal reason for the inefficiency of the conventional machines.
The present invention consists in an electrical drive system for a sewing machine having a drive shaft, the system comprising:
a DC motor for driving said drive shaft; a speed control circuit connected to said DC motor for controlling the speed of the same and including a circuit for setting a low speed; a dynamic braking circuit provided within said speed control circuit for 55 dynamically braking said DC motor upon receipt of a deceleration command signal; electromechanical braking means for frictionally braking said DC motor; first control means adapted to actuate 60 said electromechanical braking means when, during a deceleration period from the normal running speed to said low speed the speed of said DC motor has fallen to a predetermined speed which is a slightly 65 higher than said low speed; and second control means for actuating at least said electromechanical braking means upon receipt of a stopping command signal generated while said DC motor is in said 70 low speed condition.
One embodiment of the invention is an improved speed controlling system for an electric motor in a sewing machine The system includes a motor connected to a 75 power supply, a speed controlling circuit or circuits for operating the motor at variably controlled speeds, and an electrical braking circuit or circuits for braking the motor upon receiving deceleration com 80 mand from the speed controlling circuit(s) to transfer the motor from a high speed running state to a low speed runnine one.
Electromechanical braking means are provided for acting on the motor, during at 85 least a part of the braking period, the braking means being controlled by the electrical braking circuit(s) A low speed setting circuit is provided in the speed controlling circuit(s) for maintaining the 90 low speed running state caused by the electromechanical braking means and the electrical braking circuit(s) A stoppage commanding circuit is provided for stopping the motor operation, after the motor 95 has been transferred to its low speed running state by a low speed setting circuit, by actuating again, by means of a stopping command, the electrical braking circuit(s) and/or the electromechanical braking 100 Cr 041 1 590 494 1 590 494 means.
By means of this embodiment the period of time used for transferring from high speed running down to low speed running is shortened This results from employing the electric braking means and the electromechanical braking means together, the former being highly efficient during the relatively high speed running period of the machine, and the latter, whose efficiency is little affected by the speed being favorable after the machine has come down to a low speed running range There is a speedy and smooth halting of the motor, eliminating the disadvantages of the prior art.
The time span required between the deceleration command and the actual halting of the motor is reduced and, as will be described, the machine needle is stopped at a preset position.
The invention will now be described, by way of example, with reference to the accompanying drawings in which:Fig 1 is an elevation of a sewing machine in which a preferred embodiment of the present invention is incorporated; Fig 2 is an enlarged vertical sectional view, of an electromechanical braking system in the machine of Fig 1; Fig 3 is a diagram of a speed controlling circuit in the machine of Fig 1; Fig 4 is a detailed diagram of a speed controlling circuit; Fig 5 is a diagram of the logic circuit; Fig 6 is a diagrammatic view showing the position detecting means; Fig 7 is a diagram of the speed detecting circuit; Fig 8 is a diagram of the reset circuit; Fig 9 contains explanatory diagrams and tables for the D type flip-flops; Fig 10 is an explanatory diagram for the monostable multi-vibrator; and Fig 11 is an explanatory graph useful in understanding the function of the present invention.
A preferred embodiment of a drive system according to the present invention is described, with reference to the appended drawings.
As shown in Fig 1, a sewing machine 2 for industrial use is mounted on a machine table 1 in the usual way, a drive or main shaft 3 of the machine 2 is connected, via a belt 4, ‘to a D C motor 5 disposed under the table 1.
The D C motor 5 is provided with a switch box 6 attached to the left side of the housing thereof, as viewed in Fig 1.
Numeral 7 designates a pedal or foot treadle capable of being depressed toward toe side as well as heel side, which is connected through a rod 8 to an input switch or the like in the switch box 6.
-As clearly can be seen in Fig 2, an electromagnetic braking means for the’ D C.
motor 5 is disposed between a bracket 9 and a pulley 11, which is secured to an output shaft 10 of the motor 5 The electromagnetic brake includes a braking coil 70 12, having a supporting body 13 therefor attached to the bracket 9 and a member 16 which is made of steel and is attached to an elastic plate 14, which is in turn attached to the pully 11 by means of a 75 screw 15 There is a small gap of 0 2 mm or so between the supporting body 13, and the plate 14 When the coil 12 is energized the member 16 is attached towards the coil and the elastic plate 14 will be 80 deflected to allow the member 16 to engage with the supporting body 13.
Referring to Figs 3 and 4, the D C.
motor 5 is connected, via a full-wave rectifier 18, to an A C power source 17 A 85 transistor 19 for driving power is connected in series to the D C motor and a transistor for dynamic braking power is connected across the terminals of the power source The bases of these transistors 19, 90 are driven by respective voltages from a speed controlling unit 21 Across a power supply lead 22 of 15 volts and lead 23 of 0 volt, which are connected to the speed controlling unit 21, are connected a 95 variable resistor 24 (potentiometer) for low-speed-setting and a variable resistor (potentiometer) for speed controlling with the object of varying the speed command for the D C motor 5 A tap 24 a 100 of the potentiometer 24 for low-speedsetting can be manually moved by an operator, and a tap 25 a of the potentiometer for speed controlling is connected to the pedal 7 so it can be moved by an 105 operator pressing downwardly with his toes.
An input terminal 26 of the speed controlling unit 21 can receive a speed commanding voltage via three different routes, 110 a first of which comes from the potentiometer 24 for low-speed-setting via a normally open contact 27 b of a first reed relay 27, a second of which comes from the power supply lead 23 via a normally open 115 contact 28 b of a second reed relay 28, and a third of which comes from the potentiometer 25 for speed controlling via a normally open contact 29 b of a third reed relay 29 Numerals 93 and 94 respectively 120 designate respective diodes Coils 27 a, 28 a, and 29 a of respective reed relays 27, 28, and 29 are energized by transistors, 30, 31, and 32, which are respectively connected thereto, as shown in Fig 5 The 125 earlier mentioned coil 12 is energized by a transistor 33.
The speed controlling unit 21 will be explained by referring to Fig 4 An output signal 52 from a comparator 34 is 130 1 590494 produced as a result of comparison between commanding input voltage 51 from the input terminal 26 and the value which renders a negative feed back E M F voltage Ef from the D C motor 5 as well as a positive feedback load current If This output signal 52 is amplified by an amplifier 35 for supply to an inter-lock circuit 36, which determines the supply of driving pulses in accordance with the output signal 52 from the comparator 34, to the driving power transistor 19 and braking power transistor 20, respectively through amplifiers, 37 and 38 These two transistors 19 and 20 are basically supplied with continuous but mutually inversely phased pulses, i e, when pulses to one side are larger in width those to the other side will be smaller Thus, when the speed commanding voltage is higher than a voltage produced according to the actual rotation number, i e, in the rising stage the driving power transistor 19 is conductive and the braking power transistor 20 is nonconductive, and on the contrary in the falling stage the braking power transistor is conductive and interrupts the current to the driving power transistor 19 While the rotation speed is constant or unvaried conduction takes place alternately and almost evenly in the two transistors 19 and When the phase relation of the pulses is in an intermediate condition between the abovementioned cases, the time of the conduction is so controlled as to make either one of the two transistors 19 and 20 conduct for a little longer than the other.
When the pedal 7 is in the neutral position or actuated towards the heel side, a toe side depress switch 39, in Fig 5, generates a high level voltage signal (it is at 12 volts and is hereinafter designated «H» for short), and when the pedal 7 is depressed towards the toe side to actuate the switch, it generates a low level voltage signal designated «L» When the pedal 7 is in the neutral position or actuated towards the toe side a, heel side depress switch 40 generates a low level voltage signal L, and in case of actuation towards the heel side, a high level voltage signal H.
Referring to Figs 5 and 6, a needle lower position sensing Hall element 41 and a needle upper position sensing Hall element 42, are disposed above and below the machine drive shaft 3 with a 180 phase difference around the periphery of the drive shaft 3 On a rotary circular plate 43 secured to the drive shaft 3 is fixed a permanent magnet 44 At every approach to either of the Hall elements ( 41 or 42) the elements generate L signals and at the rest of the time generate H signals.
On the drive shaft 3 (Fig 1) is disposed a magnetic pole wheel 45 (Fig 7) which is composed of a plurality of permanent magnets, with their N and S poles alternately placed so as to make a circular form as a whole, as shown in Fig 7 Confronting the pole wheel 45 is a magnetic resist 70 ance element 46, to which is connected an amplifier 47 f»or producing, upon rotation of the magnetic pole wheel 45, an almost sine-wavelike output, whose frequency is directly related to the angular velocity of 75 the wheel 45 A Schmidt circuit 48 (Fig.
5) shapes the wave-form of the output from the amplifier 47, the output stage of the Schmidt circuit 48 being connected to a first D type flip-flop, 49 The input and 80 output terminals of the flip-flop 49 are shown in Fig 9 (a) in an enlargement, wherein Q is an output terminal, Q an output terminal, CK a clock input terminal, CL a clear terminal, D a data input ter 85 minal, and PR a preset terminal The truth table therefor is shown in Figs 9 (b) and (c); Fig 9 (d) is a table for reading the data of a rising clock pulse Two other D type flip-flops, a second one being 90 and a third one 51, are of completely identical construction to the first D type flip-flop 49.
A monostable multi-vibrator 52 is provided for determining the energization time 95 for the braking coil 12, the details thereof being shown in Fig 10 While a » 3 » input terminal of the multivibrator is kept at H, a » 4 » input terminal being assumed to be at L, the application of a trigger pulse to a 100 » 5 » input terminal will cause a » 7 » output terminal to produce a monostable output.
While the » 3 » input terminal is kept at H, the » 4 » input terminal is L, and application of a trigger pulse to the » 5 » input terminal 105 will, upon a rise occurring in the » 5 ‘ input trigger pulse, cause the » 7 » output terminal to produce a monostable output Applying L to the » 3 » input terminal will render the » 7 » output L, both the » 4 » and » 5 » 110 remaining unaffected.
A first variable timer 53 for speed detection determines the energization start timing for the braking coil 12, the timing being usually so set as to generate an H 115 signal 2 to 3 mili-seconds after the application of the H to the same input terminal.
A second variable timer 54 for speed detection is for determining the timing of the release of energization of the braking coil 120 12, the timing thereof being usually so set as to generate an H signal 5 to 6 miliseconds after the impression of an H on the input terminal thereof A third variable timer 55 for speed detection is for 125 detecting a change in running speed of the D.C motor to a low speed condition, the timing thereof being usually so set as to generate an H signal 20 mili-seconds after the impression of an H signal on the input 130 1 590 494 terminal thereof A fourth variable timer 56 is associated with the needle upper position detecting Hall element 42, generating an H signal a short while after the application of an H to the input terminal thereof, and restricting the driving of the D C.
motor 5 in the meantime even if the pedal 7 should be depressed In other words, the timer 56 can function as a safety circuit for preventing the needle from interfering with the thread cutting device, because driving of the DC motor 5 can be prevented while the thread cutting is performed, from the detection of the needle upper position to the complete stopping of the machine at the needle upper position.
Fig 8 is a reset circuit operative at the time when power is supplied During a constant interval of time from the time the power is supplied to a time which is determined by the resistor 57 and the capacitor 58, the output IR is H and the output IR is L After the interval of time has elapsed the output IR becomes L and the output JR becomes H The outputs IR and JR in Fig 8 are applied respectively to all the identical designations shown in Fig 5.
An OR circuit 59 takes as one input the Q output of the first D type flip-flop 49 and as a second input the output of an inverter 60, which takes, as its input, the output (of the first variable timer 53 A NAND circuit 61 takes, as its inputs, the output of the OR circuit 59 and the output of an OR circuit 62 An output of the NAND circuit 61 is applied via an inverter 63 to the first variable timer 53 The output of this timer 53 is applied to the clock input terminal CK of the second D type flip-flop 50; and the output from the output terminal Q of the flip-flop 50 is applied, via an inverter 64, to an OR circuit 65, whose output, when ‘H, will render the transistor 33 conductive.
An OR circuit 66 takes, as one input, the Q output of the first D type flip-flop 49 and as a second input the output of an inverter 67, which takes, as its input, the output of the second variable timer 54 A NAND circuit 68 takes, as its inputs, the output of the OR circuit 66 and the output of the OR circuit 62 The output of the NAND circuit 68 is applied via an inverter 69 to the second variable timer 54 An OR circuit 70 takes, as its inputs, the output from the aforementioned i R and the inyerter 67, whilst the output thereof is applied to the preset input terminal PR of the second D type flip-flop 50 An OR circuit 71 takes, as its input, the Q output of the first D type flip-flop 49; and a NAND circuit 72 takes, as its inputs, the output of the OR circuit 71 and the output of the OR circuit 62, the output of the circuit 72 being applied via an inverter 73 to the third variable timer 55 The output of the timer 55 is applied via an inverter 74 to the clear input terminal CL of the third D type flip-flop 51 To the clock input terminal CK of the third D type flip 70 flop 51 is applied via an inverter 75, the output from the needle lower position detecting Hall element 41.
A NAND circuit 76 takes, as its inputs the output Q of the third D type flip-flop 75 51 and the output of an OR circuik 77, the output of the circuit 76 applied being to the input terminal » 5 » of the monostable multi-vibrator 52, to the base of the transistor 30, and to the base of the tran 80 sistor 31, via an inverter 78 An OR circuit 81 and another OR circuit 80, from a flip-flop 82, wherein the circuit 81 takes, as one input, an output from the heel side depress switch 40, which has been reversed 85 by an inverter 83, and the circuit 80 takes as one input the output of the JR and as a second input the output of an inverter 84, which has the output of the fourth variable timer 56 as its input.
A similar flip-flop 85 is composed of an OR circuit 86 and an OR circuit 87, wherein the circuit 86 takes, as one input, the output of the needle upper position detecting Hall element 42, and the circuit 87 95 takes, as its inputs the output JR and the O output of the third D type flip-flop 51.
The output of the OR circuit 87, one of the constituting members of the flip-flop 85, is applied to the fourth variable timer 100 56, after having been reversed by an inverter 88, and also to one of the input terminals of the OR circuit 77 The other input terminal of the OR circuit 77 is connected to the output terminal of the 105 OR circuit 81 in the flip-flop 82 A NAND circuit 89 takes, as its inputs, the output of the OR circuit 62, after reversal by an inverter 90, and the output of the OR circuit 80 in the flip-flop 82 The output of 110 the circuit 89 is applied to the base of the transistor 32 after having been reversed by an inverter 91 A thread cut controlling circuit 92 has in Duts respectively connected to the Q output of the third D type 115 flip-flop 51, the output of the OR circuit 80 in the flip-flop 82, the output of the OR circuit 86 in the flip-flop 85, and the output of the thread cut position detecting Hall element 93 which cooperates with the 120 permanent magnet 44 The thread cutting means (not shown) will be started, to function when the D C motor 5 is below the low speed and the pedal 7 is heeldepressed, by the low speed driving of the 125 D.C motor 5 and the rising of the needle from the lower position up to the top to actuate the uppermost Hall element 93; and the thread cutting operation will be stopped as soon as the detecting of the 130 1 590494 thread position is made by the needle upper position detecting Hall element 42.
The operation and function of the present embodiment will now be described with reference to Fig 5 At the time power is supplied the input of the clear terminal CL of the first D type flip-flop 49 is at a logic ONE level and the input of the preset terminal PR is at a logic ZERO level; so the O output therefrom will be ZERO and the output of the OR circuit 71 will be ONE.
As the output of the toe side depress switch 39 is at this time a logic ONE, one input of the OR circuit 62 will be ZERO and the output thereof will therefore be ONE, which renders all the inputs of the NAND circuit 72 at logic ONE and the output thereof ZERO To the input of the third variable timer 55 there is, in turn, applied a logic ONE, through the function of the inverter 73, which will lead to generating of an output logic ONE after a certain period of time The clear terminal of the third D type flip-flop 51 will be consequently at logic ZERO; and the output O thereof will be logic ONE, with the aid of the, preset PR’s being ONE.
On the other hand, the output of the OR circuit 81 in the flip-flop 82 is, due to the JR, at its input, at logic ZERO This logic ZERO is applied to one input of the OR circuit 77, with the result that the output thereof is a logic ONE.
As the result, the NAND circuit 76 has a logic ONE at both inputs thereof, and ZERO at the output thereof; At the » 7 » output terminal of the monostable multivibrator 52 there is generated a ZERO output with a desired width, which is in turn applied to the OR circuit 65 The output of the circuit 65 will be ONE, rendering the transistor 33 conductive and causing the braking coil 12 to be thereby energized As the member 16 is drawn to the supporting body 13 and held in contact therewith by the magnetism the machine 2 will not start working when the power is supplied.
When the logic ZERO output at the » 7 » output of the monostable multivibrator 52 is changed to a ONE, each input of the OR circuit 65 is ONE, since a logic ONE is applied from the first variable timer 53 to the clock input terminal CK of the second D type flip-flop 50, causing a logic O at the O output of the flip-flop and a logic ONE signal to be applied to the OR circuit 65 via the reversing function of the inverter 64.
The output of the OR circuit 65 then becomes ZERO to release the energization of the braking coil 12 The machine operator is allowed then to manually turn the pulley for adjusting the needle position.
The logic ZERO output from the NAND circuit 76 is applied to the base of the transistor 30, which is therefore nonconductive and consequently the coil 27 a in the first reed relay 27 is in a non 70 energized condition to keep the normally open contact 27 b thereof open On the other hand the transistor 31 is rendered conductive via an inverter 78, energizing a coil 28 a in the second reed relay 28 and 75 causing the normally open contact 28 b thereof to close The speed commanding voltage to the input terminal 26 will therefore be zero to hold the D C motor 5 in a non-operating condition 80 The logic ONE output of the OR circuit 62 is inverted by an inverter 90 and a logic O is thereby applied to the NAND circuit 89, rendering the output thereof a ONE.
This logic ONE is in turn applied to the 85 base of the transistor 32, after having been reversed by an inverter 91 The coil 29 a of the, third reed relay 29 is not energized so that the normally open contact 29 b remains open 90 In this situation a slight depressing of the pedal 7 toward toe direction causes the output of the toe side depress switch 39 to become logic ZERO, and this ZERO after having been reversed to ONE by the 95 inverter 79, is applied to one of the inputs of the OR circuit 62 Both inputs of the OR circuit 62 are therefore at logic ONE, and the output thereof becomes a logic ZERO This ZERO output is applied to 100 all of the NAND circuits 61, 68, and 72, switching all of the outputs thereof to ONE Each ONE is reversed to ZERO, by passing through a respective one of the inverters 63, 69, and 73 and applied to a 105 respective one of the timers 53, 54, and 55 for putting them in a reset condition The output of the timer 55 is reversed by the inverter 74 to become logic ONE and applied to the clearance terminal CL of 110 the third D type flip-flop 51, which makes the Q output thereof ZERO It is delivered to the NAND circuit 76 for changing the output thereof to a logic ONE.
The monostable multi-vibrator 52 does 115 not generate a logic ZERO at the » 7 » output thereof O o that the transistor 30 is conductive and the transistor 31, is non conductive, and these in turn energize the coil 27 a of the first reed relay 27 to close 120 the normally open contact 27 b, and deenergize the coil 28 a of the second reed relay 28 to, open the normally open contact 28 b As the logic ZERO output of the OR circuit 62 is reversed by the inverter 125 90, both inputs to the NAND circuit 89 will be logic ONE, and the output thereof is naturally ZERO This makes the output from the inverter 91 a logic ONE, rendering the transistor 32 conductive so 130 6 1590494 that the coil 29 a of the third reed relay 29 is energised and the normally open contact 29 b is closed At this time the tap 25 a of the speed controlling potentiometer 25 is at the lowest position in Fig 3, sending no speed commanding voltage.
The speed commanding voltage, set at a value determined by that low speed setting potentiometer 24 (circa 215 r p m) is imparted at this stage to the input terminal 26, and the power transistor 19 is energized by that speed commanding voltage and actuates the stationary D C, motor 5, which accelerates up to 215 r p m.
The D C motor 5 is readily maintained at this low speed running according to the speed command owing to the feedback of a back E M F voltage Ef and the load current If The driving power transistor 19 and the braking power transistor 20 are alternately energised as previously described, giving rise to the speed profile shown in Fig 11 ranging from t, to t 2.
When the pedal 7 is afterwards depressed further toward the toe side, the tap 25 a of the potentiometer 25 for controlling speed moves upwards (in Fig 3) for raising the speed commanding voltage applied to the input terminal 26, which accelerates the D C motor 5 as mentioned earlier The line from to to t 3 in Fig 11 is followed at this stage When the pedal 7 is depressed as far as possible the speed of rotation of the D C motor 5 is increased to approximately 4,000 r p m, which high speed running can be maintained, just as the low speed running, as shown in Fig 11 as the line between t, and t 4.
When, after the desired sewing has been finished, the pedal 7 is released (at a time to 4 in Fig 11) i e, the toe side depress switch 39 is released, the output of the switch becomes a logic ONE, which is reversed by the inverter 79 to ZERO and impressed on the OR circuit 62 It results in the output of the OR circuit 62 becoming a logic ONE, and this logic is applied to the OR circuits 61, 68, and 72 as well as to the inverter 90.
While the machine 2 is operating, rotation of the magnetic pole wheel 45, causes pulses approximating to sine-waves to be applied via the amplifier 47 to the Schmidt circuit 48 for shaping The frequency of the pulses is divided into one-half ( 1/2) by the first D type flip-flop 49 and pulses from the flip-flop are applied to the OR circuits 59, 66, and 71, these pulses are of desired width, inversely proportional to the r p m of the machine 2 As the output of the OR circuit 62 is at this time a logic ZERO, the outputs from the NAND circuits 61, 68, and 72 are always a logic ONE From the time, however, when a logic ONE output begins to be generated from the OR circuit 62, due to the release of the pedal 7, ZERO outputs are produced by the NAND circuits 61, 68, and 72 and these outputs are each reversed to a logic ONE by the inverters 63, 69, and 73 for 70 application to the timers 53, 54, and 55.
During the decelerating period (from t, to t 7 in Fig 11), up, to the moment when the machine 2 reaches an r p m in the neighborhood of 215, the third variable timer 55 75is set to maintain its output in a logic ZERO condition, not to generate a ONE output The outputs of the third D type flip-flop 51 and the NAND circuit 76 remain unchanged 80 When the output of the OR circuit 62 is switched to a logic ONE (when the pedal 7 is released), a logic ZERO from the inverter 90 is applied to the NAND circuit 89, rendering its output a ONE This 85 results in a logic ZERO being applied from the inverter 91, to the transistor 32 The coil 29 a of the third reed relay 29 is then released of its energization to open its normally open contact 29 b 90 As a result of the above, the input terminal 26 receives a low speed commanding voltage which has been determined by the variable resistor for low speed setting 24, which causes the braking power tran 95 sistor 20 to conduct, whereupon the D C.
motor 5 undergoes dynamic braking, and rapidly decelerates from high speed running to low speed running.
As soon as the machine reaches about 100 1,500 r p m ft in Fig 11) the first variable timer 53 begins to generate a ONE output which is applied to the clock input terminal CK of the 11 second D type flip-flop 50 In the result at the rising edge of each pulse 105 the O output is switched to a logic ZERO and the Q output to a ONE because of the data input terminal D being ZERO The logic ZERO is reversed by the inverter 64 and a ONE is applied to the OR circuit 110 65, which causes the OR circuit 65 to generate a ONE output to render the transistor 33 conductive The braking circuit 12 is energized by this; the member 16 is magnetically attracted to and adheres to 115 the supporting body 13 and mechanically brakes the D C motor 5 And when the D.C motor 5 comes down to an r p m.
circa 400, t 6, in Fig 11, the second variable timer 54 generates a ONE signal, which is 120 reversed to a logic ZERO by the inverter 67 The output of the OR circuit 70 is therefore a logic ONE, which is applied to the preset terminal PR of the second D type flip-flop 50, for switching the O out 125 put thereof to a logic ONE and the Q output to a ZERO This makes the output of the OR circuit 65 a logic ONE The output » 7 » of the monostable multi-vibrator 52 is ONE and the output of the OR cir 130 1 590 494 1 590 494 cuit 65 is ZERO, this releasing the energization of the braking coil 12 When the machine’s r p m has fallen to 215 or so, it is maintained as shown in t, to t 8 in Fig.
11 by the alternative energization of the driving power transistor 19 and the, braking power transistor 20.
The output from the third variable timer is then a logic ONE, which is reversed to a ZERO by the inverter 74 and applied to the clear input terminal of the third D type flip-flop 51, When the needle lower position detecting Hall element 41 generates a ZERO output, by detecting the needle lower position, this output is reversed by the inverter 75, and applied to the clock terminal CK of the third D type flip-flop 51, switching the Q output thereof to a logic ONE Both inputs of the NAND circuit 76 thus become a logic ONE and the output thereof becomes ZERO The transistor 30 is thus rendered nonconductive and the transistor 31 conductive; the coil 27 a of the first reed relay 27 is deenergized for opening the normally open contact 27 b, and the coil 28 a of the second reed relay 28 is energized to close the normally open contact 28 b thereof.
The commanding voltage to the input terminal 26 will be zero ( 0) to cause only the braking transistor 20 to conduct for dynamically braking the D C motor 5 At the » 7 » output of the monostable multivibrator 52 there is generated a logic ZERO voltage; during this period an output of ONE is generated by the OR circuit to render the transistor 33 and consequently the braking coil 12 conductive, causing the member 16 to be magnetically attracted to and to alhere to the supporting body 13 Then there occurs a dynamic braking of the machine 2 (refer to Fig 11 from t 8 to t 9) The width of the output width (ZERO in this case) of the monostable multi-vibrator 52 is set before the machine has completely stopped in order to stop it at a needle lower position.
When the pedal 7 is later depressed in a direction towards the heel, the output of the heel side depress switch 40 becomes a logic ONE, which is reversed to a logic ZERO by the inverter 83 and applied to the flip-flop 82, switching the output of the OR circuit 82 to a logic ONE and that of the OR circuit 80 to a ZERO Both inputs to the NAND circuit 89 are switched to logic ZERO, the output thereof becomes ONE and the output of the inverter 91 is also ONE, which makes the transistor 32 non-conductive and de-energises the coil 29 a of the third reed relay 29, with the result that the normally open contact thereof 29 b is opened.
As the output status of the flip-flop 85 remains unchanged, both inputs of the OR circuit 77 are at a logic ONE and the output thereof is of course ZERO, which ZERO is applied to the NAND circuit 76, rendering its output ONE; This makes the transistor 30 conductive and the transistor 70 31 non-conductive The coil 27 a of the first reed relay 27 is consequently energized to close the normally open contact 27 b thereof, and the coil 28 a of the second reed relay 28 is energized to open the normally 75 open contact 28 b thereof This makes the machine 2 move at low speed from the needle lower position upwards.
When an output is generated, in this condition, by the thread cut position de 80 tecting Hall element 92, the thread cut controlling circuit 91 is operated and actuates the thread cutting mechanism (not shown).
As soon as the needle reaches the upper position (t 11 in Fig 11) and makes the 85 needle upper position detecting Hall element 42 produce an output which is logic ZERO, the output of the flip-flop 85 is reversed to render the output of the OR circuit a logic ONE and that of the OR 90 circuit 87 a ZERO This causes one of the inputs of the OR circuit 77 to become ZERO, and consequently the output becomes ONE Both inputs of the NAND circuit 76 become ONE to render the out 95 put thereof ZERO The machine 2 is in this way subjected to a dynamic braking as well as a mechanical braking at the same time, in a similar way to the needle lower stoppage, for being halted at the needle 100 upper position Energization of the thread cut controlling circuit 91 is released at the moment when the needle reaches the upper position, i e, when the output of the OR circuit 86 of the flip-flop 85 becomes ONE 105 Completion of the thread cutting operation may sometimes be slightly later than this needle upper detecting moment according to the mechanism of the machine The output of the OR circuit 87 of the flip-flop 110 is, due to the needle upper detection, reversed to a logic ONE by the inverter 88, which ONE is, after having been delayed a certain period of time by the fourth variable timer 56, conveyed to the inverter 115 84 This logic ONE is then reversed to a ZERO by the inverter 84 and delivered as an input to the OR circuit 80 of the flip-flop 82 whereby the output of the OR circuit 80 becomes ONE and that of the 120 OR circuit 81 a ZERO From the OR circuit 80 an output ONE is delivered to one input terminal of the OR circuit 62.
Depressing the pedal 7 at this point in a direction towards the toe, makes both 125 inputs of the OR circuit 62 a logic ONE, causing the D C motor 5 to start, as earlier stated Even if, by mistake, the pedal 7 is toe-depressed before the thread cutting mechanism has been actuated by heel 130 1 590494 depressing the pedal 7 to carry out the needle upper position detection, the D C.
motor 5 cannot be started, because ( 1) due to the maintenance of the logic ZERO at the output of the OR circuit 86 of the flip-flop 85 and the logic ONE at the output of the OR circuit 87 and ( 2) due to the fact that no logic ZERO is applied to the OR circuit 80 of the flip-flop 82, in the flip-flop 82 the OR circuit 81 generates a ONE output and the OR circuit 80 generates a ONE output, consequently one of the inputs of the OR circuit 62 is ZERO.
This mechanism is so to speak, a safety circuit for protecting the machine 2 from being damaged due to an interference between the thread cutting apparatus and the needle The reason for inserting the fourth variable timer 56 resides in making a compensation by restraining the machine 2 from operation, during the time after the needle upper position has been detected until the various mechanisms (including the thread cut mechanism) are completely stopped (including inertia).
In the abovementioned embodiment, during deceleration from high speed running to low speed running by means of a dynamic brake, the electromechanical brake is only applied between the range from 1,500 to 400 r p m The reason for this is that a simultaneous application of the mechanical brake and the dynamic brake is apt to increase the wear on the D C motor 5 and to deteriorate the braking effect During the above range of the rotation speed the contacting portions are less worn and the braking effect is high.
Various forms of mechanical braking are available to cover different ranges of the dynamic braking As for the electric braking, besides dynamic braking, inverse voltage braking, regenerative braking, etc, are also practicable This invention is not limited to D C motors and can be applied to induction motors or the like.
What is mentioned above in greater detail can ‘be summarized in other words as follows:
( 1) while causing a motor to slow down in response to a deceleration command, from high speed running to low speed running by means of an electric braking circuit; ( 2) actuating a mechanical braking means to act on the motor during at least a part of the period during which the electric braking operative and ( 3) actuating, by means of a stopping conitytand, the electric braking circuit and/ or {the mechanical braking means to stop the motor.
It means that the simultaneous application of the dynamic brake and the mechanical braking during the period of transference from high speed running to low speed jrunning for a larger part of the period from the deceleration command to the complete stop of the motor It is an advantageous parallel use of the dynamic 70 brake and the mechanical brake for halting the motor smoothly and speedily.

Claims (11)

WHAT WE CLAIM IS: –

1 An electrical drive system for a sewing machine having a drive shaft, the 75 system comprising:
a DC motor for driving said drive shaft, a speed control circuit connected to said DC motor for controlling the speed of the same and including a circuit for setting a 80 low speed, a dynamic braking circuit provided within said speed control circuit for dynamically braking said DC motor upon receipt of a deceleration command signal, 85 electromechanical braking means for frictionally braking said DC motor, first control means adapted to actuate said electromechanical braking means when, during a deceleration from the normal 90 running speed to said low speed, the speed of said DC motor has fallen to a speed which is slightly higher than said low speed, and second control means for actuating at 95 least said electromechanical braking means upon receipt of a stopping command signal generated while said DC motor is in said low speed condition.

2 An electrical drive system as claimed 100 in claim 1, in which said first control means comprises detecting means adapted when said DC motor has fallen to a speed which is higher than said low speed by a pre 105 determined amount to generate a detection signal, and means for actuating said electromechanical braking means in response to said detection signal 110

3 An electrical drive system as claimed in claim 1, in which said first control means comprises means for generating a speed representative signal, 115 first means responsive to the speed representative signal and adapted, when said DC motor has fallen to a speed slightly higher than said low speed, to generate a first detecting signal,
120 second means adapted to detect when the speed of said DC motor has fallen to a speed lower than the speed detected by said first detecting means and then to generate a second detecting signal, and 125 means for energizing said electromechanical braking means in response to said first detecting signal and de-energizing the same in response to said second detecting signal 130 1 590494

4 An electrical drive system as claimed in claim 3, irt which said speed representative signal generating means comprises a magnet pole wheel adapted, when drivingly connected with said drive shaft, to generate a variable frequency signal of frequency representative of the speed of said drive shaft, and a sensing element co-operating with said magnetic pole wheel for generating said speed representative signal.

An electrical drive system as claimed in claim 3, in which each of said first and second detecting means includes means for detecting the width of the speed representative pulse signal.

6 An electrical drive system as claimed in any one of the preceding claims, in which said speed control circuit comprises speed control means, operable by a foot treadle in the machine, for controlling the acceleration and the deceleration of said DC motor.

7 An electrical drive system as claimed in any one of the preceding claims, including means for producing said deceleration command signal upon release of a foot treadle.

8 An electrical drive system as claimed 30 in any one of the preceding claims, further comprising a needle position detecting means which is attached in use, to said drive shaft and is for generating said stopping command 35 signal.

9 An electrical drive system as claimed in any one of the preceding claims, in which said second control means is adapted to actuate both said dynamic braking 40 circuit and said electromechanical braking means.

An electrical drive system as claimed in any one of the preceding claims, wherein said DC motor has a bracket accomo 45 dating said electromechanical braking means attached thereto.

11 An electrical drive system for a sewing machine, the system being constructed, arranged and adapted to operate 50 substantially as hereinbefore described with reference to, and as illustrated in, the accompanying drawings.
MATHYS & SQUIRE, Chartered Patent Agents, Fleet Street, London EC 4 Y l AY.
Agents for the Applicants.
Printed for Her Majesty’s Stationery Office by The Tweeddale Press Ltd, Berwick-upon-Tweed, 1981.
Published at the Patent Office, 25 Southampton Buildings, London, WC 2 A l AY, from which copies may be obtained.

GB5860/78A
1977-02-18
1978-02-14
Electrical drive systems for sewing machines

Expired

GB1590494A
(en)

Applications Claiming Priority (1)

Application Number
Priority Date
Filing Date
Title

JP1743277A

JPS53103113A
(en)

1977-02-18
1977-02-18
Device for controlling motor

Publications (1)

Publication Number
Publication Date

GB1590494A
true

GB1590494A
(en)

1981-06-03

Family
ID=11943852
Family Applications (1)

Application Number
Title
Priority Date
Filing Date

GB5860/78A
Expired

GB1590494A
(en)

1977-02-18
1978-02-14
Electrical drive systems for sewing machines

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US
(1)

US4137860A
(en)

JP
(1)

JPS53103113A
(en)

BR
(1)

BR7800970A
(en)

CA
(1)

CA1094205A
(en)

GB
(1)

GB1590494A
(en)

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Assignee
Title

US4211177A
(en)

1979-04-30
1980-07-08
The Singer Company
Automatic slow speed for skip stitch mode

DE2938625A1
(en)

1979-09-25
1981-04-09
Frankl & Kirchner GmbH & Co KG Fabrik für Elektromotoren u.elektrische Apparate, 6830 Schwetzingen

CIRCUIT ARRANGEMENT FOR ENERGY SAVING

JPS5833979A
(en)

1981-08-20
1983-02-28
Mitsubishi Electric Corp
Drive device for sewing machine

US4627370A
(en)

1981-08-20
1986-12-09
Mitsubishi Denki Kabushiki Kaisha
Sewing machine drive device

US4513676A
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1982-08-30
1985-04-30
Microdynamics, Inc.
Method and apparatus for automatically decelerating and stopping a sewing machine motor

KR860002174B1
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1982-09-25
1986-12-22
마쯔시다덴기산교 가부시기가이샤
Driving device of sewing machine

JPS59105494A
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1982-12-09
1984-06-18
三菱電機株式会社
Control apparatus in sewing machine

JPH0657280B2
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1985-09-05
1994-08-03
三菱電機株式会社

Sewing machine controller

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1985-10-17
1987-04-28
Brother Ind Ltd
Driving device for sewing machine

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1986-07-03
1997-08-13
ブラザー工業株式会社

Motor control device in sewing machine

JPH0790066B2
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1986-11-07
1995-10-04
蛇の目ミシン工業株式会社

Electric sewing machine speed setting device

JP2700550B2
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1987-11-06
1998-01-21
蛇の目ミシン工業株式会社

Lock stitch control device for electronic sewing machine

DE3802784C1
(en)

1988-01-30
1989-08-17
Pfaff Haushaltmaschinen Gmbh, 7500 Karlsruhe, De

JPH03149091A
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1990-10-18
1991-06-25
Mitsubishi Electric Corp
Sewing machine drive device

EP0505660B1
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1991-03-27
1996-08-14
COMELZ S.p.A.
Control unit for an electric drive motor of industrial processing machinery.

JP2876818B2
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1991-05-20
1999-03-31
ブラザー工業株式会社

Sewing machine with automatic thread trimmer

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1998-10-23
2000-03-14
Westra; Michael A.
Coil inserter for binding a stack of sheets together

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2004-04-13
2009-07-30
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ELECTRIC GRINDING MACHINE WITH LOW PROFILE

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1971-01-20
1974-04-16
Cutters Machine Co Inc
Needle positioner for a sewing machine

US3860860A
(en)

1973-04-03
1975-01-14
Kollmorgen Photocircuits
Motion control system for direct current motors, particularly in sewing machine uses

JPS50146451A
(en)

1974-05-15
1975-11-25

1977

1977-02-18
JP
JP1743277A
patent/JPS53103113A/en
active
Pending

1978

1978-02-14
GB
GB5860/78A
patent/GB1590494A/en
not_active
Expired

1978-02-17
US
US05/879,106
patent/US4137860A/en
not_active
Expired – Lifetime

1978-02-17
BR
BR7800970A
patent/BR7800970A/en
unknown

1978-02-17
CA
CA297,178A
patent/CA1094205A/en
not_active
Expired

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US4137860A
(en)

1979-02-06

CA1094205A
(en)

1981-01-20

BR7800970A
(en)

1978-09-19

JPS53103113A
(en)

1978-09-08

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