Device for driving a sewing machine

Claim 2

A machine driving apparatus comprising a machine driving brushless motor which has a permanent magnet in a rotor, switches the energization phase of the stator winding in accordance with the position of the rotor, a speed detector which detects the rotational speed of the machine shaft or the motor, a needle position detector which detects the position of the machine needle, a machine pedal for generating speed instruction signals and stop instruction signals, a speed control means which compares a speed instruction signal answering the displacement amount of said machine pedal with a speed detection signal detected by said speed detector to control the rotating speed of said motor, a needle position control means which reversely rotates said motor and damps it with a stop instruction signal based on the operation of said machine pedal and a needle position detection detected by said needle position detector to stop the machine needle in a given position.

Claim 3

A machine driving apparatus in accordance with Claim 1, wherein a needle position controlling means starts the reverse rotation damping of the motor with a needle position detection pulse signal to count a given number of pulses of a speed detection pulse signal detected by a speed detector thereby finishing the reverse rotation damping.

Claim 4

A machine driving apparatus in accordance with Claim 1, wherein a needle position control means starts the reverse rotation damping of the motor with a stop instruction signal, detect the stop condition to complete the reverse rotation damping.

Claim 5

A machine driving apparatus in accordance with Claim 1, wherein the speed detector is composed of a speed detecting permanent magnet rotating integrally with the shaft of a motor and a magnetic resistance element disposed opposite to said permanent magnet.

Claim 6

A machine driving apparatus in accordance with Claim 1, wherein a needle position detector is composed of an encoder using light.

Claim 7

A machine driving apparatus comprising a driving motor composed of a brushless motor for driving a machine shaft, a rotor position detector for detecting the rotor position of said motor, a distribution circuit which switches the energization phase of the stator winding of a motor in accordance with a signal from said rotor position detector, a speed detector for detecting the rotational speed of the machine shaft or the motor, a needle position detector for detecting the position of the needle shaft, a speed instructing unit for generating a speed instruction signal in accordance with the operation of the machine pedal, a position instructing unit for generating a position instructing signal which becomes a stop instructing signal in accordance with the operation of said machine pedal, a comparison circuit which compares a speed instructing signal with a speed detecting signal or a position instructing signal with a position detecting signal to output a difference signal, a drive circuit which closes a current proportional to said difference signal to the stator winding selected by said distribution circuit to drive said motor, a decision circuit which decides the positive and negative of the difference signal to be outputted from said comparison circuit to switch the operational mode of said distribution circuit into a positive operational torque generating mode and a reverse operational torque generating mode, wherein said motor is damped in reverse operation by a position instructing signal in accordance with the operation of said machine pedal and a needle position detecting signal detected by said needle position detector to stop the machine needle in a given position.

Claim 8

A machine driving apparatus comprising a driving motor composed of a brushless motor for driving a machine shaft, a rotor position detector for detecting the rotor position of said motor, a distribution circuit which switches the energization phase of the stator winding of a motor in accordance with a signal from said rotor position detector, a speed detector for detecting the rotational speed of the machine shaft or the motor, a needle position detector for detecting the position of the needle shaft, a speed instructing unit for generating a speed instruction signal in accordance with the operation of the machine pedal, a position instructing unit for generating a position instructing signal which becomes a stop instructing signal in accordance with the operation of said machine pedal, a comparison circuit which compares a speed instructing signal with a speed detecting signal or a position instructing signal with a position detecting signal to output a difference signal, a drive circuit which closes a current proportional to said difference signal to the stator winding selected by said distribution circuit to drive said motor, a decision circuit which decides the positive and negative of the difference signal to be outputted from said comparison circuit to switch the operational mode of said distribution circuit into a positive operational torque generating mode and a reverse operational torque generating mode, wherein said motor is damped in reverse operation by a position instructing signal in accordance with the operation of said machine pedal and a needle position detecting signal detected by said needle position detector to stop the machine needle in a given position.

Claim 9

A machine driving apparatus in accordance with Claim 6, wherein a reverse operation damping of the motor is started with a position instructing signal to be generated by a position instructing unit, a given number of pulses of a speed detection pulse signal detected by a speed detector is counted to complete the reverse operation damping.

Claim 10

A machine driving apparatus in accordance with Claim 6, wherein a reverse operation damping of the motor is started with a position instructing signal to be generated by a position instructing unit, a stop condition is detected by a speed detector to complete the reverse operation damping.

Claim 11

A machine driving apparatus in accordance with Claim 6 or Claim 8, wherein a position instructing unit is adapted to generate a position instructing signal when the rotational speed of the motor has reached a given low speed with the machine pedal being stepped and thereafter being returned to the neutral position.

Claim 12

A machine driving apparatus comprising a machine driving brushless motor which has a permanent magnet in a motor, switches the energization phase of the stator winding in accordance with the position of the rotor, a speed detector which detects the rotational speed of the machine shaft, a needle position detector which detects the position of the machine needle, a machine pedal for generating speed instruction signals and stop instruction signals, a speed control means which compares a speed instruction signal answering the displacement amount of said machine pedal with a speed detection signal detected by said speed detector to control the rotating speed of said motor, a needle position control means which reversely rotates said motor and damps it with a stop instruction signal based on the operation of said machine pedal and a needle position detection detected by said needle position detector to stop the machine needle in a given position, wherein a rotor of said motor is secured to the top shaft of the machine, the stator of said motor is secured to the head frame inner peripheral portion of the machine.

Claim 13

A machine driving apparatus comprising a machine driving brushless motor which has a permanent magnet in a motor, switches the energization phase of the stator winding in accordance with the position of the rotor, a speed detector which detects the rotational speed of the machine shaft, a needle position detector which detects the position of the machine needle, a machine pedal for generating speed instruction signals and stop instruction signals, a speed control means which compares a speed instruction signal answering the displacement amount of said machine pedal with a speed detection signal detected by said speed detector to control the rotating speed of said motor, a needle position control means which reversely rotates said motor and damps it with a stop instruction signal based on the operation of said machine pedal and a needle position detection detected by said needle position detector to stop the machine needle in a given position, wherein a rotor of said motor is secured to the top shaft of the machine, the stator of said motor is secured to the head frame inner peripheral portion of the machine.

Claim 14

A machine driving apparatus in accordance with Claim 10, having a lubricating oil feed mechanism into which one portion of the lubricating oil of the machine flows.