JPH08107988A - Driving device for sewing machine - Google Patents

Abstract

PURPOSE: To sufficiently reduce the vibration of a sewing machine frame, especially, that of an arm by eliminating the vibration of a bearing by controlling a driving means and displacing auxiliary mass by a control means. CONSTITUTION: A control circuit 88 controls the driving of piezoelectric actuators 94a, 94b so as to minimize the vibration detection signals of acceleration sensors 90a, 90b setting signals from an encoder 60 and a needle bar position detector 62 as input signals. The piezoelectric actuators 94a, 94b perform vertical expanding/contracting motion by a control signal from the control circuit 88, and drive weights 92a, 92b vertically. The reaction of an inertia force generated by the vertical driving of the weights 92a, 92b is applied to the bearings 33a, 33b, and it is synthesized with the reaction generated by the motion of a needle bar mechanism and a needle thread take-up mechanism, consequently, the reaction applied to the bearings 33a, 33b can remarkably be reduced. Therefore, the vibration generated in a sewing machine arm 22 can remarkably reduced, and a generated noise can also be reduced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a driving device for a sewing machine, which is designed to reduce the vibration generated in the arm of the sewing machine frame, particularly the arm, during the operation of the sewing machine.

[0002]

2. Description of the Related Art Conventional sewing machines generally have a mechanism for reciprocating or swinging a needle bar 40, a balance 36, etc., as shown in FIGS. Further, it has at least one motor 18 as a drive source for driving the needle bar 40 and other mechanisms. A drive belt 32 is stretched between the drive shaft of the motor 18 and the upper pulley 30. In addition, the upper shaft pulley 3
0 is fixed to the right end of the upper shaft 31 and is driven by the driving force transmitted by the driving belt 32.
It can be rotated together with it.

Further, the upper shaft 31 is rotatably attached to the arm 22. A balance crank 34 is fixed to the left end of the upper shaft 31, and one end of the balance 36 is rotatably attached to the balance crank 34. In addition, the balance crank 34,
The needle bar crank 42 is fixed, and one end of a connecting rod 44 is rotatably attached to the needle bar crank 42. A needle bar holder 46 is rotatably attached to the other end of the connecting rod 44, and the needle bar 40 is fixed to the needle bar holder 46.

In the above-mentioned structure, when the motor 18 is started, its power is driven by the drive belt 32 and the upper pulley 3.
0, upper shaft 31, balance crank 34, needle bar crank 42,
It is transmitted to the needle bar 40 via the connecting rod 44 and the needle bar holder 46, whereby the needle bar 40 reciprocates in the vertical direction. Further, the rotation of the upper shaft 31 is transmitted to the balance 36 via the balance crank 34, and the balance 36 reciprocally swings vertically.

The inertial force due to the reciprocating and swinging motions of the respective mechanisms becomes a vibrating force for vibrating the sewing machine arm 22 via the bearings 33a and 33b of the upper shaft 31, and vibrates in the sewing machine arm 22 and the bed 20. And there was noise.

In order to reduce the vibration and noise, in the conventional sewing machine, the balance crank 34 is provided with an unbalance amount corresponding to the inertial force and acts as an eccentric weight to balance the inertial force. You can see what you did.

[0007]

[Problems to be Solved by the Invention] However, the needle bar,
The inertial force generated by the reciprocating and oscillating motions of the balance or the like contains a lot of higher-order components of the rotation frequency. Part 1 that can be balanced by the eccentric weight is
It was only the secondary component, and had no effect on the higher components.

Further, the sewing machine arm 22 is manufactured in a structure as shown in FIG. 7. Due to the structure, the resonance of the mode in which the tip portion vibrates in the vertical direction or the front-back direction has an eigenvalue at a relatively low frequency. Therefore, it is generally difficult to avoid resonance when a vibrating force containing a large amount of higher-order components as described above acts or when the rotational speed range used is wide such as in an industrial sewing machine. Therefore, in the conventional sewing machine, when the sewing machine is operated at a high speed, the inertial force generated by the movement of the needle bar mechanism, the balance mechanism, or the like becomes a vibrating force, which causes resonance in the arm 22 and increases vibration and noise. hand,
It was uncomfortable for the user.

The present invention has been made to solve the above-mentioned problems, and an object thereof is to provide a driving device for a sewing machine capable of sufficiently reducing the vibration of the sewing machine frame, particularly the vibration of the arm. There is.

[0010]

In order to achieve this object, a driving device for a sewing machine according to claim 1 of the present invention has an upper shaft supported by at least two bearings and rotationally driven by a motor. Then, in a driving device of a sewing machine in which a needle bar or the like is moved by the rotation of the upper shaft to perform sewing, a rotation angle detecting means for detecting a rotation angle of the upper shaft or the like and vibration of the bearing are detected. The vibration detecting means, the bearing, or an auxiliary mass movably provided in the vicinity thereof, a driving means for displacing the auxiliary mass, and a signal from the rotation angle detecting means are input to the vibration detecting means. A control means for controlling the driving means so as to minimize the vibration to be detected, and by controlling the driving means by the control means, the auxiliary mass is displaced and moved. So that cancel out the vibration of the receiving.

According to a second aspect of the present invention, in the drive device for a sewing machine, an elastic body capable of expanding and contracting is provided at or near the bearing, and the auxiliary mass is attached to the free end of the elastic body.

In the drive device for a sewing machine according to a third aspect of the present invention, the drive means is a piezoelectric actuator.

According to a fourth aspect of the present invention, in the drive device for a sewing machine, the rotation angle detecting means, the vibration detecting means, the auxiliary mass and the driving means are provided only on the bearing closest to the needle bar among the bearings.

Further, the driving device of the sewing machine according to claim 5 is
The rotation angle detection means is configured to detect the rotation angle of the drive motor that drives the upper shaft.

[0015]

According to the sewing machine driving apparatus of the first aspect of the present invention configured as described above, the signal detected by the rotation angle detecting means is used as an input signal to minimize the vibration detected by the vibration detecting means. The control means controls the drive means. As a result, the vibration of the bearing is canceled by the displacement movement of the auxiliary mass driven by the driving means. Therefore, the vibration of the bearing is significantly reduced, and the noise radiated from the arm is also significantly reduced.

Further, according to the driving device of the sewing machine of the second aspect, the auxiliary mass is attached to the free end portion of the elastic body which is provided in the bearing or in the vicinity thereof and capable of expanding and contracting.
According to the theory of the dynamic vibration absorber, if the mass of the weight and the spring constant of the elastic body are set in a predetermined relationship, the resonance of the arm can be effectively suppressed.

Further, according to the sewing machine drive device of the third aspect, since the drive means is constituted by the piezoelectric actuator, the displacement movement of the auxiliary mass can be finely and precisely controlled, and the vibration of the bearing can be suppressed. The reduction can be further ensured.

Further, according to the driving device for a sewing machine of claim 4, the rotation angle detecting means, the vibration detecting means, the auxiliary mass and the driving means are provided only on the bearing closest to the needle bar among the bearings. did. Generally, in a sewing machine, the largest vibration force is generated in the bearing closest to the needle bar, so this vibration force can be sufficiently canceled with a simple structure, and the vibration of the arm is sufficiently reduced.

Further, according to the drive device for a sewing machine of claim 5, the rotation angle detecting means is configured to detect the rotation angle of the drive motor for driving the upper shaft.
The rotation angle signal of the drive motor can be used without specially providing the rotation angle detection means in relation to the upper shaft, and the control configuration can be further simplified.

[0020]

Embodiments of the present invention will be described below with reference to the drawings.

First, a first embodiment of the present invention will be described with reference to FIGS. Since the driving of the upper shaft 31 and the operations of the needle bar mechanism, the balance mechanism and the like accompanying it are the same as those of the conventional example, detailed description thereof is omitted. In FIG. 1, an encoder 60 and a needle bar position detector 62 are provided on the right end of the upper shaft 31. Acceleration sensors 90a and 90b, which constitute the vibration detecting means of the present invention, and mass drive mechanisms 98a and 98b are attached to bearings 33a and 33b that rotatably support the upper shaft 31, respectively.

The mass drive mechanisms 98a and 98b are shown in FIG.
The configuration is shown in. That is, the weights 92a and 92b constituting the auxiliary mass of the present invention are attached to one end of the piezoelectric actuator 94 as the driving means of the present invention, and the other ends of the piezoelectric actuators 94a and 94b are the bearings 33a, It is fixed to 33b.

As shown in the block diagram of FIG. 3, the electric control system of the sewing machine driving apparatus in the first embodiment has an encoder 60, a needle bar position detector 62, acceleration sensors 90a and 90b, and a piezoelectric actuator. 94a, 94
b and a control circuit 88.

The encoder 60 detects the number of rotations of the upper shaft 31, and the needle bar position detector 62 detects the position of the needle bar during the vertical reciprocating motion of the needle bar. The encoder 60 and the needle bar position detector 62 constitute the rotation angle detecting means of the present invention for detecting the rotation angle of the upper shaft 31.

The control circuit 88 receives the signal from the rotation angle detecting means as an input signal, and uses the acceleration sensors 90a, 9a and 9a.
The drive of the piezoelectric actuators 94a and 94b is controlled so that the vibration detection signal of 0b is minimized. The piezoelectric actuators 94a and 94b move up and down by a control signal from the control circuit 88, and the weights 92a and 92b are moved.
Drive up and down. The reaction force of the inertial force generated by the vertical movement of the weights 92a, 92b acts on the bearings 33a, 33b, and is combined with the reaction force generated by the movement of the needle bar mechanism and the balance mechanism, resulting in the bearings 33a, 33b. The reaction force acting becomes very small. Therefore, the vibration generated in the sewing machine arm 22 is significantly reduced, and the generated noise is also reduced.

Next, a second embodiment embodying the present invention will be described. In the first embodiment, the case where the piezoelectric actuator is used as the driving means for the auxiliary mass has been described, but in this embodiment, the coil spring is used for supporting the auxiliary mass and the electromagnetic driving method is applied as the driving means. Describe. Since the basic structure is almost the same as that of the first embodiment, only the mass drive mechanisms 98a and 98b are shown in FIG.
Will be described in detail.

The mass drive mechanisms 98a and 98b are composed of weights 92a and 92b which form the auxiliary mass of the present invention, coil springs 99a and 99b as elastic bodies of the present invention, and coils attached to the weights 92a and 92b. 95a, 9
5b, the permanent magnets 96a and 96b provided near the coils 95a and 95b, and the permanent magnets 96a and 96b.
b is attached, and is composed of yokes 97a and 97b that form a magnetic field around the coils 95a and 95b. Coil 95a, 95b, permanent magnet 96a, 96b
And the yokes 97a and 97b constitute the driving means of the present invention.

The weights 92a and 92b are attached to one ends of the coil springs 99a and 99b, and the other ends are fixed to the bearings 33a and 33b. Further, the yokes 97a and 97b are also bearings 33a and 33b.
It is fixed to.

The basic operation is almost the same as that of the first embodiment. The control circuit 88 receives the signal from the rotation angle detecting means as an input signal and controls the current flowing through the coils 95a and 95b so that the vibration detection signals of the acceleration sensors 90a and 90b are minimized. Permanent magnets 96a, 96b and yoke 97
a, 97b in the magnetic field formed by the coils 95a, 9b
An electromagnetic force proportional to the current value is generated at 5b, and the weight 9
2a and 92b are driven up and down. Bearings 33a, 33b
The reaction force of the inertial force generated by the vertical movement of the weights 92a and 92b acts on the bearings 33a, 92b, and is combined with the reaction force generated by the movement of the needle bar mechanism, the balance mechanism, etc.
The reaction force acting on a and 33b becomes very small. Therefore, the vibration generated in the sewing machine arm 22 is significantly reduced, and the generated noise is also reduced.

According to the theory of the dynamic vibration absorber, the weights 92a, 9
The natural frequency of the mass drive mechanisms 98a and 98b, which is obtained from the mass of the movable part obtained by adding the mass of 2b and the mass of the coils 95a and 95b, and the spring constant of the coil springs 99a and 99b, is the natural frequency of the arm in the vertical direction. When set to be substantially equal to, the vertical resonance of the arm is suppressed to an extremely small value. Therefore, in this embodiment, the arm resonance can be effectively suppressed with a small driving energy. Further, even if the control circuit 88 or the like fails to operate due to some failure, there is an effect that the resonance of the arm can be suppressed.

Next, a third embodiment embodying the present invention will be described. In the first embodiment, the case where both the bearings 33a and 33b that support the upper shaft 31 are vibration-reduced and damped is described, but in the present embodiment, the needle bar-side bearing 33a is used.
Only when applied to. Since the basic structure is almost the same as that of the first embodiment, only different parts will be described in detail with reference to FIGS.

As shown in FIG. 4, in this embodiment, the acceleration sensor 90 and the mass drive mechanism 98 are attached only to the needle bar bearing 33a. In this case, as shown in FIG. 5, the electrical control system is a simple control system including only one acceleration sensor 90 and one piezoelectric actuator 94. The principle of vibration and noise reduction is similar to that of the first embodiment, but in this case, it acts only on the bearing 33a.

In the actual sewing machine, the bearings 33a and 33b are used.
Since the reaction force applied to is much larger on the needle bar side, it is possible to obtain almost the same effect by applying it only to the needle bar bearing 33a. In addition, since the first embodiment is a two-channel control system, it is necessary to control the influence of one piezoelectric actuator on the other acceleration sensor as well, so the control circuit itself is complicated and required for control. It took a long time. In this embodiment, since only one channel needs to be controlled, the circuit becomes simple and the control time is shortened.

Next, a fourth embodiment embodying the present invention will be described. In each of the above-described embodiments, the case where the rotation angle of the upper shaft 31 is used as the input signal to the control circuit has been described, but in the present embodiment, the rotation angle of the upper shaft drive motor is used instead of the rotation of the upper shaft 31. Described below is the case of using as an input signal to the. Since the basic structure is almost the same as that of the first to third embodiments, only different parts will be described in detail with reference to FIG.

That is, in the block diagram of the electric control system of FIG. 2, instead of the signals from the encoder 60 and the needle bar position detector 62, the control box 8 for controlling the motor 18 is used.
The rotation angle signal of the motor used within 0 is used. Since the upper shaft 31 is driven by the drive belt 32 at a constant reduction ratio, similar control can be performed using the rotation angle signal of the motor 18. In this case, there is an advantage that the rotation angle signal of the motor used in the control box 80 can be used to control the rotation of the motor.

The present invention is not limited to the embodiments described in detail above, and various modifications can be made without departing from the spirit of the invention. For example, in each of the above embodiments, the acceleration sensor is used as the vibration detecting means, but a speed sensor or a displacement sensor may be used.

[0037]

As is apparent from the above description, according to the sewing machine driving apparatus of the present invention, the vibration generated in the sewing machine arm by the needle bar mechanism, the balance mechanism, etc. can be reduced in the bearing portion of the upper shaft. And, the noise due to the vibration can be surely reduced.

[Brief description of drawings]

FIG. 1 is a schematic perspective view of a sewing machine according to a first embodiment of the present invention.

FIG. 2 is a configuration diagram of a mass drive mechanism of the first embodiment.

FIG. 3 is a block diagram of an electric control system of the first embodiment.

FIG. 4 is a configuration diagram of a mass drive mechanism according to a second embodiment of the present invention.

FIG. 5 is a schematic perspective view of a sewing machine according to a third embodiment of the present invention.

FIG. 6 is a block diagram of an electrical control system of a third embodiment.

FIG. 7 is an external perspective view of a conventional sewing machine.

FIG. 8 is a schematic perspective view of a conventional sewing machine.

[Explanation of reference signs] 18 motor 22 sewing machine arm 31 upper shaft 33a, 33b bearing 42 needle bar crank 40 needle bar 60 encoder 62 needle bar position detector 88 control circuit 90, 90a, 90b acceleration sensor 92a, 92b weight 94, 94a, 94b Piezoelectric actuator 95a, 95b Coil 96a, 96b Permanent magnet 97a, 98b Yoke 98, 98a, 98b Mass drive mechanism 99a, 99b Coil spring

Claims (5)

[Claims] 1. A sewing machine drive device having an upper shaft supported by at least two bearings and rotationally driven by a motor, and rotating the upper shaft to move a needle bar or the like for sewing. A rotation angle detecting means for detecting a rotation angle of the upper shaft, a vibration detecting means for detecting vibration of the bearing, an auxiliary mass movably provided in the bearing or in the vicinity thereof, and the auxiliary A drive means for displacing the mass, and a control means for controlling the drive means so as to minimize the vibration detected by the vibration detection means by receiving a signal from the rotation angle detection means as input are provided by the control means. A sewing machine drive device characterized in that the drive means is controlled to displace the auxiliary mass to cancel the vibration of the bearing. 2. The driving of the sewing machine according to claim 1, wherein an elastic body capable of expanding and contracting is provided at or near the bearing, and the auxiliary mass is attached to a free end portion of the elastic body. apparatus. 3. The driving device for a sewing machine according to claim 1, wherein the driving means is a piezoelectric actuator. 4. The sewing machine according to claim 1, wherein the rotation angle detecting means, the vibration detecting means, the auxiliary mass and the driving means are provided only on the bearing closest to the needle bar among the bearings. Drive. 5. The driving device for a sewing machine according to claim 1, wherein the rotation angle detecting means is configured to detect a rotation angle of a drive motor that drives the upper shaft.