JPH0788275A - Silencing device - Google Patents

Abstract

PURPOSE:To provide a silencing device which can actively cancel the sounds generated by vibration of a cover joined with the frame of a sewing machine, printer, etc. CONSTITUTION:Vibration transmitted from the frame 1 of a sewing machine, printer, etc., is sensed by a sensor 4, and the sensing signal generated is fed to a signal processing device 8 via an amplifier 9 and A/D converter 16, and signal given by this signal processing device 8 is passed to a vibration generator for controlling 3 via a D/A converter 17. At a plurality of object points to be vibro-isolated, a plurality of vibration sensors 5, 6, 7 for evaluating are furnished to sense the error included in the control result, and the outputs of these evaluational sensors 5, 6, 7 are introduced to the signal processing device 8 via amplifiers 10, 11, 12 and A/D converters 13, 14, 15.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a silencer for actively eliminating noise generated by a sewing machine or a printer.

[0002]

2. Description of the Related Art Conventionally, a sewing machine has a mechanism as shown in FIG. Specifically, at least one motor 2 is used as a drive source for driving a needle bar 38, a main shaft 26, etc. described later.
The timing belt 22 is stretched between the drive shaft of the motor 20 and the main shaft pulley 24. The main shaft pulley 24 is fixed to the right end of the main shaft 26, and can be rotated together with the main shaft 26 by the driving force transmitted from the timing belt 22.

Further, the main shaft 26 is rotatably attached to a frame 40 shown in FIG.
A balance crank 28 is fixed to the left end of 6, and one end of a balance 30 is rotatably attached to the balance crank 28. Further, a needle bar crank 32 is fixed to the balance crank 28, and the needle bar crank 3 is fixed.
One end of a connecting rod 34 is rotatably attached to 2. In addition, the connecting rod 3
A needle bar holder 36 is rotatably attached to the other end of the needle bar 4, and a needle bar 38 is fixed to the needle bar holder 36.

With the above structure, the rotation of the motor 20 is transferred to the needle bar 38 via the timing belt 22, the main shaft pulley 24, the main shaft 26, the balance crank 28, the needle bar crank 32, the connecting rod 34, and the needle bar holder 36. , Which causes the needle bar 38 to reciprocate in the vertical direction. Further, the rotation of the main shaft 26 is transmitted to the balance 30 via the balance crank 28, and the balance 30 reciprocates.

The above-mentioned mechanism is supported by the frame 40 shown in FIG. 4, and is covered by the front cover 42, the left cover 44, the upper cover 46, the right cover 48, the lower cover 50, and the bottom cover 52. At least a part of these covers was fixed to the frame 40 by fastening parts such as screws.

[0006]

However, in the conventional sewing machine as described above, vibration is generated by mechanical movement such as reciprocating movement of the needle bar and the balance and rotation of the motor, and the vibration is generated via the frame. The noise is generated by being transmitted to the cover, and the vibration of the cover vibrates the surrounding air.

The present invention has been made in order to solve the above-mentioned problems, and an object of the present invention is to provide a silencer capable of actively extinguishing radiated sound generated by cover vibration.

[0008]

In order to achieve this object, in the muffler of the present invention, a sensor for detecting the vibration of the cover attached to the frame and a predetermined coefficient are added to the signal detected by the sensor. And a signal processing device for obtaining a control signal by multiplying the control signal by controlling a vibration generator for control by the control signal to cancel the vibration at the vibration damping target point. In this case, the signal processing device obtains an average control result at a plurality of the vibration suppression target points, and adaptively processes the coefficient according to the result. It is characterized in that it is configured as follows.

[0009]

In the silencer of the present invention having the above structure, the evaluation sensor detects the control result at the damping target point. Further, the signal processing device obtains an average value from a plurality of control results at the vibration suppression target point, and adaptively processes the coefficient according to the average value.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 shows an example in which the silencer of the present invention is applied to a sewing machine. That is, the balance / needle bar mechanism (not shown) described in detail in the conventional example is supported by the frame 1 of the sewing machine. In addition, the sound deadening cover 2 is connected to the frame 1 by the connecting component 1
8 and the vibration generator 3 for control are joined. The vibration transmitted from the frame 1 to the sound deadening cover 2 is detected by the sensor 4, the detection signal is given to the signal processing device 8 via the amplifier 9 and the A / D converter 16, and processed by the signal processing device 8. The signal is given to the control vibration generator 3 via the D / A converter 17.

On the other hand, a plurality of vibration sensors for evaluation 5, 6 and 7 for detecting an error in the control result are provided at a plurality of vibration suppression target points.
Are arranged, and the outputs of these vibration sensors 5, 6, 7 for evaluation are fed to amplifiers 10, 11, 12 and A / D converters 13, 1
It is introduced into the signal processing device 8 through 4, 15.
Here, each evaluation vibration sensor is attached near the antinode of the vibration mode of the upper cover 2. Although only the upper cover is shown in FIG. 1 for easy description of the embodiment, the left and right covers and the front cover are also joined to the frame 1 and have the same active vibration damping function as the upper cover. .

Next, the operation of the sewing machine of this embodiment to which the muffling device of the present invention is applied will be described below with reference to the flowchart of FIG.

First, in step 1 (S1), the detection vibration sensor 4 acquires a control signal X (n-i), which is the vibration of the upper cover 2, and uses this signal as an amplifier 9 and an A / D converter 16. To the signal processing device 8 via.

In step 2 (S2), the upper cover 2
The vibration output signal y (n) for canceling the vibration of is calculated by the following equation.

[0016]

[Equation 1]

Here, h (i) represents a transfer function required for vibration damping by an impulse response. These signal processings are executed by the signal processing device 8.

In step 3 (S3), the output signal y (n) obtained from the equation (1) is output from the control vibration generator 3 via the D / A converter 17.

In step 4 (S4), each vibration suppression target point (evaluation vibration sensor 5, 6, 7) when vibration suppression control is performed.
Error signal (e1,
e2, e3) are measured using the respective vibration sensors 5, 6, 7 for evaluation. That is, it suffices that the vibration at the control target point (in the vicinity of the evaluation vibration sensors 5, 6, 7) is sufficiently eliminated by the vibration output from the control vibration generator 3.
If the above-mentioned transfer function h is not optimum, generally, a sufficient effect cannot be obtained.

In step 5 (S5), a plurality of error signals (e
1, e2, e3), an average error signal (e) is obtained.

In step 6 (S6), it is determined whether or not the transfer function h is changed depending on whether or not the error signal (e) obtained by processing the plurality of error signals is sufficiently small.
That is, when the error signal (e) is large, the process proceeds to S7 to change the transfer function h.

In step 7 (S7), a new transfer function h _NEW that can obtain a sufficient damping effect is obtained using the following equation.

H _NEW = h _OLD + K · e · X (n−i) (2) Here, h _OLD is a transfer function that has been used so far, and K is a convergence parameter. . After updating the transfer function, the process proceeds to S1 and an output signal to be output from the control vibration generator 3 is obtained using the new transfer function h _NEW .

As described above, since the vibration of the upper cover 2 is actively controlled to suppress the vibration as much as possible, the sound emitted from the upper cover 2 is reduced.

In this embodiment, the average value of a plurality of error signals is used to determine whether or not the transfer function is updated. However, each error signal is weighted according to the mounting position of the vibration sensor for evaluation. You may use the error signal calculated | required by.

Although this embodiment has been described using a sewing machine, the present invention can be applied to a machine in which a cover is joined to a frame, such as a printer or a washing machine.

[0027]

As is apparent from the above description, since the muffler of the present invention controls the vibration of the cover so that the vibration of the entire cover is minimized, the radiated sound generated from the cover can be suppressed. Noise reduction is possible.

[Brief description of drawings]

FIG. 1 is a configuration diagram of a sewing machine in which a silencer of the present invention is implemented.

FIG. 2 is a flowchart showing the operation of the sewing machine.

FIG. 3 is a configuration diagram of a balance / needle bar mechanism of a conventional sewing machine.

FIG. 4 is a configuration diagram of a frame and a cover of a conventional sewing machine.

[Explanation of symbols]

 1 Frame 2 Top Cover 3 Control Vibration Generator 4 Detection Vibration Sensor 5 Evaluation Vibration Sensor 6 Evaluation Vibration Sensor 7 Evaluation Vibration Sensor 8 Signal Processor 9 Amplifier 13 A / D Converter 17 D / A Converter 18 Connecting parts

Claims (2)

[Claims] 1. A control vibration is provided by a sensor for detecting a vibration of a cover attached to a frame, and a signal processing device for obtaining a control signal by multiplying a signal detected by the sensor by a predetermined coefficient. A silencer configured to cancel a vibration at a vibration control target point by controlling a generator, comprising one or more evaluation sensors for detecting a control result at the vibration control target point, and the signal processing device having a plurality of evaluation sensors. The silencer is configured to obtain an average control result at the damping target point and adaptively process the coefficient according to the result. 2. The silencer according to claim 1, wherein the evaluation sensor is installed on an antinode of a vibration mode of the cover.