JP2014126144A - Vibration reducing device of engine generator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent an amplitude increase of vibration in an engine generator in which an engine and an electric generator are mounted on a bed.SOLUTION: A bed 3 is provided on a floor 1 through a spring 2a and a damper 2b. An engine 4 and an electric generator 5 are fixed on the bed 3, and the engine 4 is connected with the electric generator 5 to constitute an engine generator 6. A vibration reducing device 7 of the engine generator is provided which prevents an amplitude W from being increased by the occurrence of vibration in the engine generator 6 due to variation of the number of revolution N of the engine 4. A pair of rails 8 are provided while being fixed to the bed 3 on both sides of the engine 4 and the electric generator 5. Weights 9 are movably provided along each rail 8 at each rail 8. A drive unit 10 is provided which reciprocates the weights 9 along the rails 8.

Description

  The present invention relates to a vibration reduction device for an engine generator.

  The engine generator is provided with a generator and an engine fixed on a bed. The bed is provided on the floor surface via a spring and a damper, and an input shaft of the generator and an output shaft of the engine are connected to each other.

  In the engine generator, the number of revolutions of the engine is set in accordance with the frequency of the power source that generates power. However, there is no problem if the engine speed is constant, but there is a problem that the vibration of the engine generator increases when the engine speed fluctuates. The vibration of the engine generator includes vibration of the entire bed supported by the spring and the damper, and vibration due to deformation of the bed by the generator and the engine fixed on the bed.

  There are the following techniques for reducing vibration caused by rotation.

  In the invention described in Patent Document 1, a stator is supported on a motor case, and the support state of the stator is changed according to the rotation speed of the stator. The rotational speed detection module detects the rotational speed of the rotating electrical machine, and drives the rotating contact or drives the rotating contact downward according to the detected rotational speed. Thereby, the stator can be floated with respect to the motor case to be in a low-rigidity support state, or the stator can be closely fixed to the motor case to be in a high-rigidity support state.

  When it is desired to emphasize heat generation in a high load state, the rotating electrical machine is in a highly rigid support state and the stator and the motor case are brought into contact with each other. If noise suppression is important in a low load state, the stator is floated with respect to the motor case in a low rigidity support state. By adapting to the operating state of the rotating electrical machine, it is possible to suppress vibration and ensure heat generation performance.

JP 2009-27790 A

  An object of the present invention is to detect in real time that the amplitude of vibration has exceeded an allowable value, move the weight to a position with a large amplitude on the engine generator, switch the natural frequency of the engine generator, and This is to prevent the machine amplitude from increasing.

  The “means for solving the problems” will be described below using the numbers used in “DETAILED DESCRIPTION”. These numbers are added to clarify the correspondence between the description of “Claims” and the description of “Mode for Carrying Out the Invention”. However, these numbers should not be used for the interpretation of the technical scope of the invention described in “Claims”.

  In the engine generator, the vibration of the engine is transmitted to the bed until the engine rotates and reaches a certain rotation speed, and the bed is bent or twisted. For this reason, vibrations of the entire engine generator including the bed, engine, and generator occur. The vibration of the engine generator resonates and increases in amplitude when passing through the resonance point of the natural frequency of the engine generator.

  In particular, when power is generated by an engine generator in a country where the power situation is unstable, the engine speed is not constant, and therefore, vibration with a large amplitude is likely to occur in the engine generator. For example, when power generation is performed at a frequency of 50 Hz, the engine speed fluctuates, and the frequency of the generated power source fluctuates in the range of 47 to 53 Hz. When approaching, the amplitude of vibration increases due to resonance.

  Because the country's power situation is different, the frequency variation is also different. Since the setting of the vibration reduction device for the engine generator cannot be fixed in advance, it is desirable to be able to adjust it locally.

  Therefore, the present invention is configured as follows.

  A bed (3) is provided on the floor (1) via a spring (2a) and a damper (2b). An engine (4) and a generator (5) are fixed on the bed (3) to constitute an engine generator (6).

  An engine generator vibration reduction device (7) is provided that suppresses an increase in the amplitude (W) of vibration of the engine generator (6) due to fluctuations in the rotational speed (N) of the engine (4). That is, it is configured as follows.

  A pair of rails (8) are provided on both sides of the engine (4) and the generator (5) fixed to the bed (3). Each rail (8) is provided with a weight (9) movably along each rail (8). A drive unit (10) for reciprocating the weight (9) along the rail (8) is provided.

The frequency (F _j ) of the excitation force of the engine (4) approaches the natural frequency (F ₀ ) of the engine generator (6), and the amplitude (W) of the engine generator (6) is an allowable value (W ₁ ) A detection unit (12) for detecting in real time that the value exceeds ₁ ) is provided. The weight (9) for changing the natural frequency (F ₀ ) of the engine generator (6) to a different natural frequency (F ₁ ), (F ₂ ) based on the signal from the detector (12). A calculation unit (13) for calculating the position is provided. A control unit (14) for outputting a control signal to the drive unit (10) based on the numerical value calculated by the calculation unit (13) is provided.

  The engine generator (6) includes the vibration reduction device (7) for the engine generator.

The frequency (F _j ) of the excitation force of the engine (4) in the engine generator (6) comprising the engine (4), the generator (5) and the bed (3) is the characteristic of the engine generator (6). It approaches the frequency (F ₀ ) and detects in real time that the amplitude (W) of the engine generator (6) has exceeded the allowable value (W ₁ ). In order to change the natural frequency (F ₀ ) of the engine generator (6) to different natural frequencies (F ₁ ) and (F ₂ ), the position of the weight (9) is calculated. Based on the calculated numerical value, the weight (9) is moved along the rail (8). As a result, the natural frequency (F ₀ ) of the engine generator (6) is changed to different natural frequencies (F ₁ ) and (F ₂ ), and the amplitude (W) of the engine generator (6) is increased. Suppress.

  According to the present invention, by moving the weight in the length direction of the rail to vary the natural frequency of the engine generator, the engine generator resonates with the vibration force of the engine and the vibration amplitude of the engine generator The vibration of the engine generator is reduced by avoiding the increase of the engine. For this reason, the vibration of the engine generator can be reduced without increasing the rigidity of the bed.

FIG. 1 is a front view of an engine generator (Embodiment 1). FIG. 2 is a right side view of the engine generator (Embodiment 1). FIG. 3 is a plan view of the engine generator (Embodiment 1). FIG. 4 is a configuration diagram showing a portion that performs an operation from detection of the vibration amplitude of the bed to movement of the weight (Embodiment 1). FIG. 5A is a graph showing the relationship between the engine speed and the vibration frequency of the excitation force when the engine speed is increased (Embodiment 1). FIG. 5B is a graph showing the relationship between the frequency and amplitude of the engine generator when the engine speed is increased (Embodiment 1). FIG. 6A is a graph showing the relationship between the engine speed and the vibration frequency when the engine speed is decreased (Embodiment 1). FIG. 6B is a graph showing the relationship between the vibration frequency and amplitude of the engine generator when lowering the engine speed (Embodiment 1). FIG. 7 is a flowchart for explaining the procedure for changing the natural frequency of the engine generator by moving the weight (Embodiment 1).

  Embodiments for implementing a vibration reduction device for an engine generator according to the present invention will be described below.

  As shown in FIGS. 1 to 3, a bed 3 is provided on a floor surface 1 via springs 2 a and dampers 2 b as elastic members.

  An engine 4 and a generator 5 are fixed on the bed 3, and an engine generator 6 is configured by connecting an output shaft 4 a of the engine 4 and an input shaft 5 a of the generator 5.

  An engine generator vibration reducing device 7 is provided for suppressing vibrations in the engine generator 6 caused by fluctuations in the rotational speed N of the engine 4 and increasing the amplitude W of the engine generator 6.

  The engine generator vibration reducing device 7 is configured as follows. As shown in FIGS. 2 and 3, on both sides of the engine 4 and the generator 5, a pair of belt-like rails 8 are provided fixed to the side surface of the bed 3. Each rail 8 is provided with a weight 9 that is movable along each rail 8.

  The configuration of the weight 9 will be described below. As shown in FIG. 2, the weight 9 has a groove 9a having a transverse T-shaped cross section. On the other hand, a retaining portion 8a is formed on the side of the rail 8, and the cross-sectional shape of the rail 8 is formed in a horizontal T shape. The horizontal T-shaped portion of the rail 8 is fitted into the horizontal T-shaped groove 9 a of the weight 9, and the weight 9 can move without being detached from the rail 8.

  A driving unit 10 that reciprocates the weight 9 along the rail 8 is provided. The configuration of the drive unit 10 will be described below. A plurality of wheels 11 having a fixed axis in the horizontal direction perpendicular to the rail 8 are provided along the length direction of the rail 8 perpendicular to the paper surface of FIG. One of these wheels 11 is connected to a motor (not shown).

  The weight 9 is supported by the wheel 11, the screw shaft is rotatably supported along the length of the rail 8, the weight 9 is screwed to the screw shaft, and the screw shaft is fixed to the bed 3. It is also possible to adopt a configuration connected to the motor.

Then, a part for action to move the weight 9 along the rail 8 detects that the amplitude W of the engine generator 6 exceeds the allowable value W ₁ that vibrates will be described with reference to FIG. 4 . When the engine 4 rotates, a vibration generating force is generated. When the frequency F _j of the j-th order vibration component of this vibration force approaches the natural frequency F ₀ of the engine generator 6 and the amplitude W of the engine generator 6 exceeds the allowable value W ₁ , it exceeds A detection unit 12 (not shown in FIGS. 1 to 3) for detecting this is fixed to the bed 3. In the present embodiment, as many detection units 12 as the number of vibration modes that can be grasped along the length direction of the bed 3 are provided.

Based on a signal from the detection unit 12, a calculation unit 13 is provided that calculates a position where the weight 9 is arranged in the length direction of the rail 8. This is because, in order to change the natural frequency F ₀ of the engine generator 6 to different natural frequencies F ₁ and F ₂ , it is necessary to arrange the weight 9 in a portion where the amplitude of the rail 8 is large. This is because it is necessary to calculate the position of the weight 9 in the length direction of the rail 8.

  A control unit 14 is provided that outputs a control signal to a motor (not shown) of the drive unit 10 based on the numerical value calculated by the calculation unit 13.

A method for obtaining the mass Ma of the weight 9 will be described below. In this embodiment, since the bending force and the torsional force act on the bed 3 of the engine generator 6, the vibration suppression target is set to the bending primary vibration mode or the torsional primary vibration mode. When the resonance order j following frequency F _j of the excitation force of the engine 4, coincides with the natural frequency F ₀ of the vibration due to the bending first-order vibration mode or torsional primary vibration mode, the weight can be lowered a percent In the case of using 9, the position of the weight 9 where the natural frequency F ₀ is the lowest is the maximum amplitude point.

Then, when the weight 9 is positioned at the maximum amplitude point, the natural frequency F ₀ is decreased by a percent, the mode mass is M ₀ , the mode rigidity is k ₀ , and the target natural frequency is F ₁ {= (1− a / 100) × F ₀ },
F ₀ = (1 / 2π) √ {k ₀ / M ₀ } (1)
F ₁ = (1 / 2π) √ {k ₀ / (M ₀ + M _a )} (2)
Holds.

From the above equation (2),
M _a = {k ₀ / (2πF ₁ ) ² } −M ₀ (3)
Is derived, and the mass Ma of the weight 9 can be obtained from the equation (3).

  Next, the operation of the engine generator vibration reducing device will be described.

In the engine generator, the number of rotations of the generator 5 increases / decreases due to the increase / decrease of the frequency of the electric supply system in which power generation is continued, and the vibration of the engine 4 increases / decreases accordingly. The vibration of the engine 4 is transmitted to the bed 3. When the frequency F _j of the j-th order vibration force of the engine 4 approaches the natural frequency F ₀ of the engine generator 6, the vibration of the engine generator 6 increases and the vibration amplitude W of the engine generator 6 increases. Become. Therefore, the increase / decrease in the frequency F of the engine generator 6 can be predicted based on the increase / decrease in the frequency of the power source, and the amplitude W of the engine generator 6 can be predicted based on the increase / decrease in the frequency F of the engine generator 6. Increase and decrease can be predicted. Therefore, when the amplitude W of the engine generator 6 is likely to increase, the natural frequency of the engine generator 6 is changed from a reference natural frequency F ₀ having a weight 9 at the center position of the rail 8 to another natural frequency. It can be seen that the two weights 9 may be moved toward either end of the rail 8 so as to be F ₁ and F ₂ . As a result, the amplitude W varies along the vibration curves of the other natural frequencies F ₁ and F ₂ , and the amplitude W decreases from W ₀ to W ₁ and W ₂ .

In order to calculate the position of the weight 9 such that the natural frequencies F ₁ and F ₂ are obtained as the natural frequencies of the engine generator 6, the position of the weight 9 and the natural frequencies F ₁ and F _{2 of the} engine generator 6 are Is previously grasped. Then, the position of the weight 9 on the rail 8 becomes a vibration curve at the target natural frequencies F ₁ and F ₂ from the vibration curve of the natural frequency F ₀ when the weight 9 is at the center position of the rail 8. The control unit 14 performs an operation for determining the value. The calculation unit 13 calculates the positions of the weights 9 of the target natural frequencies F ₁ and F ₂ on the rail 8.

Specifically, the control unit 14 monitors the vibration of the engine generator 6 and performs frequency analysis. When the oscillation amplitude W of the engine generator 6 approaches the allowable value W _1, the vibration is close to the allowable value W ₁ is determined by the vibration frequency or vibration due to the vibration or twisting due to bending of the bed 3. Based on the determination, the control unit 14 moves the two weights 9 from the central position on the rail 8 to the left heavy engine 4 side or to the right light generator 5 side, and the engine generator The natural frequency F ₀ of 6 is changed to different natural frequencies F ₁ and F ₂ . More specific description will be given below.

A method of moving the weight 9 that suppresses an increase in the amplitude W of vibration of the engine generator 6 when the rotational speed N of the engine 4 increases will be described with reference to FIGS. 5A and 5B. First, the weight 9 is positioned at the center of the rail 8.

When the rotational speed N of the engine 4 increases, the frequency F _{j of the j-th} vibration force acts on the engine generator 6. Then, the frequency F _j of the j-th order vibration force approaches the natural frequency F ₀ of the engine generator 6 in the bending primary vibration mode, for example. The vibration of the engine 4 is transmitted to the bed 3 and vibrates the entire engine generator 6. FIG. 5B shows the relationship between the frequency F and the amplitude W of the engine generator 6. If the natural frequency of the engine generator 6 is F _0, becomes a vibration curve of (a), if the natural frequency of the engine generator 6 is F ₁ a vibration curve of (b). In Figure 5A, when it exceeds F _{0 L} frequency F _j of the j-th order of the excitation force of the engine 4 passes through the point Q, in the graph of FIG. 5B (a), directed from the position of R ₁ point to the upper right , so that the amplitude W of the engine generator 6 exceeds the permissible value W _1.

The rotation speed of the engine 4 at the Q point is N _j L. There is a relationship of F ₀ L = j · (N _j L / 60) between the engine frequency and the engine speed. Here, j appears in increments of 0.5, 1.0, 1.5 and 0.5 when the engine 4 is a 4-stroke engine, and appears in increments of 1, 2, 3, and 1 when the engine 4 is a 2-stroke engine. .

As described above, when the frequency F _j of the j-th order excitation force of the engine 4 passes the Q point in FIG. 5A and exceeds F ₀ L, the amplitude W of the engine generator 6 exceeds the allowable value W ₁ . For this reason, the weight 9 located at the center of the rail 8 is moved toward one end of the rail 8 which is the maximum amplitude point of the bed 3 in FIG. Then, as indicated by an arrow (c) in FIG. 5B, the natural frequency F ₀ of the engine generator 6 shown in the graph (a) is reduced to the natural frequency F ₁ of the engine generator 6 shown in the graph (b). To do. That is, the vibration curve is switched from the graph (a) to the graph (b). Thus, as indicated by an arrow (D), the amplitude W of the engine generator 6 is lowered from the allowable value W ₁ of the position of R ₁ points W ₂ position of R ₂ points. Since the graph (a) is switched to the graph (b), the amplitude W decreases as the frequency N of the engine generator 6 increases.

Thereafter, with increasing rotational speed N of the engine 4, as the amplitude W of the engine generator 6 does not exceed the permissible value W _1, it returns the weight 9 to the original center of the rail 8.

On the contrary, how to move the weight 9 that suppresses the increase in the amplitude W of vibration of the engine generator 6 when the rotational speed N of the engine 4 decreases will be described based on FIGS. 6A and 6B. First, the weight 9 is positioned at the center of the rail 8.

When the rotational speed N of the engine 4 decreases, the frequency F _{j of the j-th} vibration force acts on the engine generator 6. Then, the frequency F _j of the j-th order vibration force approaches the natural frequency F ₀ of the engine generator 6 in the bending primary vibration mode, for example. The vibration of the engine 4 is transmitted to the bed 3 and vibrates the entire engine generator 6. FIG. 6B shows the relationship between the frequency F and the amplitude W of the engine generator 6. When the natural frequency of the engine generator 6 is F ₀ , the vibration curve of (a) is obtained, and when the natural frequency of the engine generator 6 is F ₂ , the vibration curve of (b) is obtained. In Figure 6A, the frequency F _j of the j-th order of the excitation force of the engine 4 is smaller than the point Q is F _{0 U,} as shown in the graph of FIG. 6B (a), the left from the position of R ₁ point As the frequency F decreases, the amplitude W of the engine generator 6 increases. Then, so that the amplitude W of the engine generator 6 exceeds the permissible value W _1.

The rotational speed of the engine 4 at the Q point is N _j U.

When the frequency F _j of the j-th order excitation force of the engine 4 becomes lower than the position of the Q point that is F ₀ U of FIG. 6A, the amplitude W of the engine generator 6 becomes the allowable value W ₁ of FIG. 6B. Exceed. For this reason, the weight 9 located at the center of the rail 8 is moved toward one end of the rail 8 which is the maximum amplitude point of the bed 3 in FIG. Then, as shown by an arrow (e) in FIG. 6B, the natural frequency F ₀ of the engine generator 6 shown in the graph (a) drops to the natural frequency F ₂ of the engine generator 6 shown in the graph (b). To do. That is, the vibration curve is switched from the graph (a) to the graph (b). Thus, as shown by the arrow (c), the amplitude W of the engine generator 6 is lowered from the allowable value W ₁ of the position of R ₁ points W ₃ position of R ₂ points. Since the graph (a) is switched to the graph (b), the amplitude W of the engine generator 6 is reduced.

Thereafter, the amplitude W of the engine generator 6 with the lowering of the rotational speed N of the engine 4 does not exceed the permissible value W _1, returns the weight 9 in the central portion of the original rail 8.

Said case, "bending" of the engine generator 6 when the amplitude W of the primary vibration mode has exceeded the allowable value W _1, reduce the amplitude W by moving the weight 9 to the position of the maximum amplitude of the engine generator 6 has been described for the case of "twisting" about even when the amplitude W of the primary vibration mode has exceeded the allowable value W _1, likewise move the weight 9 to the position of the maximum amplitude of the engine generator 6 reduce the amplitude W Will do.

FIG. 7 shows a procedure for changing the natural frequency F ₀ of the engine generator 6 by moving the weight 9 as described above. First, in step S1, a permissible value W ₁ of the amplitude W of the engine generator 6. Next, in step S <b> 2, the detection unit 12 attached to the bed 3 detects the amplitude W of the engine generator 6. In step S3, the detected value of the amplitude W is sent from the detection unit 12 to the control unit 14, and the control unit 14 monitors the amplitude W in real time. When the detected value of the detector 12 is of acceptable values W ₁ following amplitude W, the drive unit 10 does not operate, the weight 9 is held in the current position. On the other hand, the detection value may exceed the allowable value W ₁ in step S4, the arithmetic unit 13 calculates the position of suppressing weight 9 to the amplitude W of the engine generator 6 is increased.

In step S <b> 5, the control unit 14 outputs the calculated value calculated by the calculation unit 13 to the motor of the drive unit 10 as a control signal. In step S6, the weight 9 moves along the rail 8 to the calculated position. Thereby, the weight 9 occupies the calculated position, and the natural frequency of the engine generator 6 is changed from F ₀ to F ₁ , F _2, etc. in step S7.

After step S8, the same operation as described above is performed. In step S8, the amplitude W of the engine generator 6 is again detected in real time. In step S9, the detected value of the amplitude W motor tolerance W ₁ or less if the drive unit 10 does not operate, the weight 9 is held in the current position. On the other hand, if it exceeds the allowable value W _1, the position of the weight 9 which is suitable for suppressing the amplitude W of the engine generator 6 is increased returns to the step S4, the arithmetic unit 13 calculates. Then, the same process as described above is repeated.

According to this engine generator vibration reducing apparatus, the engine generator 6 is caused to vibrate by the engine 4 by moving the weight 9 in the length direction of the rail 8 to vary the natural frequency F of the engine generator 6. The vibration of the engine generator 6 is reduced by avoiding an increase in the vibration amplitude W of the engine generator 6 due to resonance. For this reason, the vibration of the engine generator 6 can be reduced without increasing the rigidity of the bed 3.

According to the engine generator 6 including the engine generator vibration reduction device 7, the above-described effect can be obtained.

According to this engine generator vibration reducing method, the above-described effects can be obtained.

  The engine generator vibration reducing device and the like according to the present invention have been described above with reference to the embodiment. However, the engine generator vibration reducing device and the like according to the present invention are not limited to the above embodiment. . Various modifications can be made to the above embodiment, and the structures described in the above embodiments can be combined with the structures described in the other embodiments.

1 ... Floor 2a ... Spring (elastic member)
2b ... damper 3 ... bed 4 ... engine 5 ... generator 6 ... engine generator 7 ... engine generator vibration reduction device 8 ... rail 9 ... weight 10 ... Driver 12 ... Detector 13 ... Calculator 14 ... Control part

Claims (3)

A bed is provided on the floor surface via an elastic member and a damper, and the engine and the generator are fixed on the bed to constitute an engine generator,
A vibration reduction device for an engine generator that suppresses an increase in amplitude of the engine generator due to vibrations in the engine generator caused by fluctuations in the rotational speed of the engine,
A pair of rails fixed to the bed on both sides of the engine and the generator, weights movably provided on the rails along the rails, and the weights reciprocating along the rails A drive unit;
A detection unit for detecting in real time that the vibration frequency of the engine vibration force approaches the natural frequency of the engine generator and the amplitude exceeds an allowable value; and a signal from the detection unit based on a signal from the detection unit. An engine generator comprising: a calculation unit that calculates a position of a weight for changing the natural frequency to a different natural frequency; and a control unit that outputs a control signal to the drive unit based on a numerical value calculated by the calculation unit Vibration reduction device. An engine generator comprising the engine generator vibration reduction device according to claim 1. Detecting in real time that the vibration frequency of the engine generator is close to the natural frequency of the engine generator and that the amplitude of the engine generator has exceeded an allowable value;
Calculating the position of the weight to change the natural frequency of the engine generator to a different natural frequency;
Based on the calculated value, move the weight along the rail,
A method of reducing vibration of an engine generator that suppresses an increase in amplitude of the engine generator by changing the natural frequency of the engine generator to a different natural frequency.

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