JP2000292303A - Electrodynamic vibration generator and vibration control method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a vibration generator capable of more inexpensive and high-accuracy horizontal control of a surface for placing a shaking table. SOLUTION: This vibration generator 1 is an electromagnetic one comprising a shaking table 2 with a specimen S to be mounted thereon, a plurality of vibration generation mechanism portions 3 positioned in lower portions of the shaking table 2 to support it while shaking the shaking table 2 by generating an AC in a moving coil 34 disposed in an air gap with a DC magnetic field formed therein, and a vibration control portion 4 for controlling the vibration of the vibration generation mechanism portions 3. Here, when a support portion 35 for supporting the shaking table 2 in each vibration generation mechanism portion 3 is displaced from a predetermined reference position, it is controlled by feeding back to each moving coil 34 a DC required to return the support portion 35 to the reference position on the basis of the vertical displacement of the support portion 35 measured by a displacement measuring means 37 for measuring the vertical displacement.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vibration generator and a vibration control method for evaluating the seismic resistance and durability of a test object by applying vibration to the test object, and more particularly, to applying a current to a coil in a magnetic field. The present invention relates to an electrodynamic vibration generator and a vibration control method using a force generated at the time.

[0002]

2. Description of the Related Art Conventionally, parts have been subjected to vibration tests under various vibration conditions from relatively small parts in the electric and electronic fields to relatively large products in the aerospace field. A vibration generator is known as a device for evaluating the earthquake resistance and durability of products and products. As such a vibration generator, for example, an electrodynamic vibration generator shown in FIG. 4 is known.

An electrodynamic vibration generator 100 shown in FIG. 4 includes an outer magnetic pole 101, an inner magnetic pole 102, an exciting coil 103, a movable coil 104, a vibrating table 105, a spring 106, and the like. The excitation coil 103 is excited by a DC current input from a power supply unit (not shown) to generate a DC magnetic field, and the outer magnetic pole 101 and the inner magnetic pole 10
2, a DC magnetic field crossing the movable coil 104 is formed. An AC current generated by a drive circuit (not shown) is supplied to the movable coil 104, and the movable coil 104 vibrates in a DC magnetic field formed in the gap G at a frequency based on the frequency of the AC current. The movable coil 104 is a vibration table 105 supported by a spring 106 installed on the upper surface of the inner magnetic pole 102.
The vibrating table 105 vibrates when the movable coil 104 vibrates. And the shaking table 105
, A test piece 107 is attached, and the test piece 107 vibrates with the vibration of the shaking table 105, so that the vibration characteristics at this time can be measured.

[0004] By the way, in the case of a relatively large and bulky test specimen, the area of the installation surface of the shaking table must be increased, but if it is so, one vibration generator (one-point support) becomes unstable, so that It is necessary to support the shaking table at a plurality of points (for example, four points). When the shaking table is supported at multiple points, there is a problem that the shaking table is inclined depending on the position of the center of gravity when the test piece is installed. Conventionally, an acceleration sensor is attached to a vibration table near each vibration generator, and control is performed using a multi-axis control device that controls the vibration so that the values of the acceleration sensors become equal.

[0005]

However, the horizontal control using the conventional multi-axis control device is less expensive and the same as the multi-axis control device because the multi-axis control device itself is expensive. There was a need for a vibration testing machine that could do this.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and an electrodynamic vibration generator and a low-cost, high-precision horizontal control of an installation surface of a vibration table are provided. It is an object to provide a vibration control method.

[0007]

According to a first aspect of the present invention, there is provided a vibration table (2) on which a test body (S) is mounted, and a vibration table located below the vibration table. A movable coil (34) including at least two or more support portions (35) for supporting a table, attached to each of the support portions, and arranged in a gap in which a DC magnetic field is formed;
An electrodynamic type comprising: a plurality of vibration generating mechanisms (3) for causing the vibration table to vibrate by passing an alternating current thereto; and a vibration controller (4) for controlling the vibration of the vibration generating mechanism. A vibration generator (1), comprising: a displacement measuring means (37) for measuring a vertical displacement when the support portion is displaced from a predetermined reference position; and a vertical measuring means for measuring the vertical displacement measured by each of the displacement measuring means. A feedback control unit (42, 43, 4) that performs feedback control for transmitting a DC current required to return the position of the support unit to the movable coil to the reference position based on the displacement.
4, 45, 46).

According to the first aspect of the present invention, the displacement measuring means measures the vertical displacement when the supporting portion for supporting the shaking table is displaced from a predetermined reference position, and the feedback controller controls each movable member. Feedback control is performed to transmit a DC current required to return the position of the support portion to the reference position in the coil, whereby a DC current required to return the shaking table to the reference position is supplied to each movable coil. Therefore, when performing a vibration test, the test can be performed with the vibration table returned to the reference position even when the vibration table is deviated from the reference position due to the center of gravity of the test body attached to the vibration table. A more accurate vibration test can be performed. In particular, if the reference position is set to a position where the shaking table is kept horizontal, the vibration test will always be performed while the vibration table is kept horizontal. Compared with the multi-axis control device, horizontal control that is inexpensive and equivalent can be performed.

Here, the displacement measuring means may be attached to a place where the displacement of the support from the reference position can be measured as a result. For example, one end is part of the support or one of the vibrating tables. And the other end may be attached to the non-vibrating part of the vibration generating mechanism. The reference position of the support portion is arbitrarily set, for example, a position where the shaking table is kept at a horizontal position may be set as the reference position, or a position where the shaking table is inclined at a predetermined angle. The reference position may be used. The method of forming the DC magnetic field may be a method using a permanent magnet or a method using an electromagnet. As displacement measurement means,
For example, linear scale, LVDT (differential transformer), capacitor pick (charge capacity type displacement sensor), electric micrometer, etc., but are not limited thereto, and the displacement of the support from the reference position can be measured. Any means may be used as long as it is appropriate.

According to a second aspect of the present invention, there is provided the vibration control method in the electrodynamic vibration generator according to the first aspect, wherein the displacement measuring means detects a vertical position when the support portion is displaced from a predetermined reference position. By measuring the displacement in the direction, based on the displacement, by the feedback control unit, by transmitting to the movable coil a DC current required to return the position of each support unit to the reference position in each movable coil. Each support is maintained at a reference position, and the vibration table is vibrated in this state.

According to the second aspect of the present invention, a vertical displacement when the supporting portion for supporting the vibration table is displaced from a predetermined reference position is measured, and based on the displacement, each movable coil is provided with each support. Feedback control is performed to transmit the DC current required to return the position of the unit to the reference position, and the position of each support unit is returned to the reference position based on the feedback control. An alternating current for vibrating is supplied. Therefore, when performing a vibration test, the test can be performed with the vibration table returned to the reference position even when the vibration table is deviated from the reference position due to the center of gravity of the test body attached to the vibration table. A more accurate vibration test can be performed.

[0012]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram showing an embodiment of an electrodynamic vibration generator and a vibration control method according to the present invention; FIG. 1 is a diagram schematically illustrating the entire configuration of an electrodynamic vibration generator according to the present invention, and FIG. 2 is a diagram schematically illustrating a configuration of a cross-sectional portion taken along a line AA in FIG. 1. It is. FIG. 3 is a block diagram showing a main configuration relating to vibration control of the electrodynamic vibration generator of FIG.

An electro-dynamic vibration generator 1 shown in FIGS. 1 to 3 is formed in a rectangular shape in plan view and has a predetermined rigidity and a lower surface of four corners 2 a of the vibration table 2. And a vibration generating mechanism 3 (3a) supporting the vibrating table 2
To 3d) and a vibration control unit 4 connected to each of the vibration generation mechanism units 3 to perform vibration control of the vibration generation mechanism units 3.
And an operation unit 6 for inputting a predetermined operation for vibration control
And a display unit 7 for displaying vibration test conditions and vibration test results
And the like.

As shown in the side sectional view of FIG. 2, the vibration generating mechanism 3 includes an outer magnetic pole 31, an inner magnetic pole 32, an exciting coil 33, a movable coil 34, a shaking table support 35 (support), an air spring. 36, a displacement meter 37 (displacement measuring means) and the like. The outer magnetic pole 31 is a magnetic material that is magnetized by an exciting coil 33 stored inside. The inner magnetic pole 32 is a column supporting the vibrating table 2 via the air spring 36 and a vibrating table support 35 attached to the air spring 36, and a magnetic pole magnetized by the exciting coil 33. Body. A DC magnetic field is formed in a gap G between an annular protrusion 31 a formed along the circumference of the upper end of the outer magnetic pole 31 and the inner magnetic pole 32.

The exciting coil 33 is excited by a DC current supplied from a power supply to generate a DC magnetic field, and a gap G between the outer magnetic pole 31 and the inner magnetic pole 32 which is a magnetic material.
, A DC magnetic field crossing the movable coil 34 is formed.

The movable coil 34 has a shaking table support 3 based on feedback control by a feedback control circuit 43, which will be described later.
A predetermined AC current to which a DC component for returning the 5 to the reference position is added is supplied, and the DC current oscillates in a DC magnetic field formed in the gap G at a frequency based on the frequency of the AC current. The movable coil 34 is fixed to a lower end of a vibrating table support 35 supported by an air spring 36 attached to the upper surface of the inner magnetic pole 32. When the movable coil 34 vibrates, the vibrating table support 35 Vibration causes the vibration table 2 to vibrate. Furthermore, the test piece S
Is attached, and the specimen S
Vibrates, and the vibration characteristics at this time can be measured by an accelerometer (not shown) or the like.

The displacement meter 37 is composed of, for example, a linear scale, and measures the displacement of the shaking table support 35 from a reference position, that is, the displacement of the shaking table 2 in the direction perpendicular to the horizontal plane. The resulting displacement is output to the feedback control circuit 43 of the vibration control unit 4 as a displacement signal. Here, the reference position of each shaking table support 35 is a position where the shaking table 2 is kept horizontal. The term “horizontal” as used herein means that the vertical distances from the bottom of each vibration generating mechanism 3 to the joint surface between the vibration table 2 and the vibration table support 35 are all equal.

As shown in FIG. 3, the vibration control unit 4
Vibration control circuit 41, level variable device 42, feedback control circuit 4
3, an amplifier 44, a current sensor 45, a distributor 46, and the like. The vibration control circuit 41 is a circuit that generates a vibration control signal that causes the vibration table 2 to vibrate at a predetermined frequency, and corresponds to the command based on a predetermined command input on the operation unit 6 described later. A vibration control signal is generated and output to the level variable unit 42.

The level variable unit 42 receives a feedback DC signal output from a distributor 46, which will be described later, for returning each shaking table support 35 to a reference position, and receives the vibration control signal in consideration of the feedback DC signal. And outputs it to the feedback control circuit 43. The feedback control circuit 43 compares the displacement signal input from the displacement meter 37 with a reference position signal (reference signal) of the shaking table 2 and, based on the comparison result, moves the shaking table support 35 to the reference position. A feedback control signal to be fed back to the amplifier 44 is generated and output to the amplifier 44. Further, the feedback control circuit 43 receives the vibration control signal output from the level varying unit 42 and outputs the vibration control signal to the amplifier 44.

The amplifier 44 amplifies the feedback control signal and the vibration control signal output from the feedback control circuit 43, and outputs them to the movable coil 34 via the current sensor 45 as a feedback current and a vibration current, respectively. The current sensor 45
Detects the feedback current output from the amplifier 44 and outputs it to the distributor 46. The distributor 46 receives the feedback current output from the current sensor 45, and outputs a feedback DC signal corresponding to the feedback current to each level variable device 42. Thus, the level converter 42 and the feedback control circuit 4
3. A feedback control unit 50 is constituted by the amplifier 44, the current sensor 45, and the distributor 46. The feedback control unit 50 can perform feedback control for returning the shaking table support unit 35 to the reference position. ing. The feedback control by the feedback control unit 50 is performed in a state before the vibration after the test sample S is placed on the vibration table 2.

The operation unit 5 is composed of, for example, a keyboard (not shown), and is used for inputting or selecting a command relating to the mass measurement and the vibration test of the test object S. The selected command is displayed on the CRT screen. When the command is input, a signal based on the command (for example, a vibration start signal) is output to the vibration control unit 4. In addition, the operation unit 5 can select a set test acceleration from the test acceleration displayed on the display unit 6, and a vibration test is performed at the selected set test acceleration.

The display unit 6 is, for example, a CRT (Cathod).
e Rey Tube) display device, and the contents of the input command and the result data of the vibration test are displayed on the CRT screen.

Next, a description will be given of a vibration control operation (method) of the specimen S by the vibration generator 1. First, after turning on the power of the vibration generator 1, a jig (not shown) is attached to the vibration table 2.
The test body S is installed by the following. Then, a vibration test start command is input by a keyboard operation of the operation unit 5, and a vibration start signal is thereby output to the vibration control unit 4.

When this vibration test start signal is input to the vibration controller 4, the displacement meter 37 measures the displacement of the shaking table 2 in the direction perpendicular to the horizontal plane, and the measured displacement is the displacement. The signal is output to the feedback control circuit 43 as a signal.

Next, the feedback control circuit 43 compares the displacement signal with the reference position signal of the shaking table support 35, and generates a feedback control signal for returning the shaking table support 35 to the reference position according to the difference. The signal is output to the amplifier 44. Next, the feedback control signal is amplified by the amplifier 44 and output to the distributor 46 via the current sensor 45 as a feedback current. Subsequently, based on the feedback current output from the current sensor 45, the distributor 46 outputs a feedback DC signal corresponding to each feedback current to each level variable device 42. Then, each level variable unit 42 adjusts the level of the vibration control signal output from the feedback control circuit 43 based on the feedback DC signal. The above operation is performed once after the test object S is fixed to the vibrating table 2 (may be performed again in some cases). Thereafter, the vibration test is performed in a state where the information is input to each level variable device 42. Will be

After the feedback control is performed, the vibration start signal input by the operation unit 5 is output to the vibration control circuit 41, where a predetermined vibration control signal is generated, and then the level changer 42. Next, the level changer 42 adjusts the vibration control signal in consideration of the DC component for returning the shaking table support 35 to the reference position, and outputs the vibration control signal to the feedback control circuit 43. The vibration control signal output to the feedback control circuit 43
And is amplified by the movable coil 34 as an oscillating current.
Supplied to Thereby, the vibrating table 2 vibrates at a predetermined frequency. At this time, the AC current including the DC current for returning the shaking table support 35 to the reference position is applied to each of the movable coils 34.
The vibration table 2 tilted by the position of the center of gravity of the specimen S is returned to the horizontal position, and the vibration test is performed.

According to the above-described electro-dynamic vibration generator 1 and the vibration test method using the electro-dynamic vibration generator 1 according to the present invention, the vibration table in which the vibration table 2 is horizontal by the displacement meter 37 is provided. The vertical displacement when the support 35 is displaced from the reference position is measured, and the direct current necessary for returning the position of the shaking table support 35 to the reference position is supplied to each movable coil 34 by the feedback control circuit 43 and the like. A feedback control for transmitting power is performed, and an AC current to which a DC current necessary for returning the position of the shaking table support unit 35 to the reference position is added to each movable coil 34.
When the vibration test is performed, the test should be performed with the vibration table 2 returned to a horizontal position even when the vibration table 2 is displaced from the horizontal position due to the center of gravity of the test sample S attached to the vibration table 2. This makes it possible to perform more accurate vibration tests, and at the same time it is possible to perform inexpensive horizontal control using a conventional multi-axis controller and to perform horizontal control equivalent to that of a multi-axis controller. Become.

The mode of the embodiment according to the present invention is not limited to the above-described embodiment, but may be appropriately changed to a mode in which the effect of the present embodiment is obtained. Although the vibration generator of the present embodiment has a four-point support structure, it may have two-point support or three-point support, or may have other multi-point supports. The configurations of the displacement meter and the vibration generating mechanism may be appropriately changed within a scope equivalent to the present invention. The feedback control circuit 43 may not be provided for each vibration generating mechanism unit, but may be configured to share one feedback control circuit 43.

[0029]

According to the first aspect of the present invention, the displacement measuring means measures the vertical displacement when the supporting portion supporting the shaking table is displaced from a predetermined reference position, and the feedback control portion controls the displacement. Feedback control is performed to transmit a DC current required to return the position of the support unit to the reference position in each movable coil, and thereby a DC current required to return the vibrating table to the reference position is supplied to each movable coil. . Therefore, when performing a vibration test, the test can be performed with the vibration table returned to the reference position even when the vibration table is deviated from the reference position due to the center of gravity of the test body attached to the vibration table. A more accurate vibration test can be performed. In particular, if the reference position is set to a position where the shaking table is kept horizontal, the vibration test will always be performed while the vibration table is kept horizontal. Compared with the multi-axis control device, horizontal control that is inexpensive and equivalent can be performed.

According to the second aspect of the present invention, the vertical displacement when the supporting portion for supporting the shaking table is displaced from a predetermined reference position is measured, and based on this displacement, each movable coil is attached to each movable coil. Feedback control is performed to transmit the DC current required to return the position of the unit to the reference position, and the position of each support unit is returned to the reference position based on the feedback control. An alternating current for vibrating is supplied. Therefore, when performing a vibration test, the test can be performed with the vibration table returned to the reference position even when the vibration table is deviated from the reference position due to the center of gravity of the test body attached to the vibration table. A more accurate vibration test can be performed.

[Brief description of the drawings]

FIG. 1 is a diagram schematically showing a configuration of a main part of an electro-dynamic vibration generator according to the present invention.

FIG. 2 is a diagram schematically showing a configuration of a cross-sectional portion taken along a line AA in FIG. 1;

FIG. 3 is a block diagram illustrating a main configuration of a feedback control unit.

FIG. 4 is a side cross-sectional view showing a configuration of a main part of a conventional electrodynamic vibration generator.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Electrokinetic vibration generator 2 Shaking table 3 Vibration generating mechanism part 4 Vibration control part 7 Power supply part 34 Moving coil 35 Shaking table support part (support part) 37 Displacement meter (displacement measuring means) 41 Vibration control circuit 42 Level variable device 43 feedback control circuit 44 amplifier 45 current sensor 46 distributor 50 feedback control unit S test sample

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 2G064 AA11 AB02 BA02 BA28 BD02 CC54 DD25 5D107 AA12 BB09 CC08 CC12 CD07 DE01

Claims (2)

[Claims] 1. A shaking table to which a test body is attached, and at least two or more supporting portions which are located below the shaking table and support the shaking table, are attached to the respective supporting portions, and a DC magnetic field is provided. A vibration generating mechanism section that vibrates the vibration table by passing an alternating current through a movable coil disposed in the formed gap; and a vibration control section that controls the vibration of the vibration generating mechanism section. An electrokinetic vibration generator, comprising: a displacement measuring unit configured to measure a vertical displacement when the support unit is displaced from a predetermined reference position; and based on the vertical displacement measured by each of the displacement measuring units. And a feedback control unit for performing a feedback control for transmitting a DC current necessary for returning the position of the support unit to the reference position to each of the movable coils. 2. The vibration control method for an electrodynamic vibration generator according to claim 1, wherein the displacement measuring means measures a vertical displacement when the support portion is displaced from a predetermined reference position. Based on the displacement, the feedback control unit transmits a DC current required to return the position of each support unit to the reference position to each movable coil to the movable coil, thereby setting each support unit to the reference position. A vibration control method, wherein the vibration table is vibrated in this state.