JPH0893843A - Vibration control structure for engine bed - Google Patents

Abstract

PURPOSE: To eliminate defectiveness that natural frequency increase of a bed for mounting engine due to rigidity enhancement can not cope with speed-up and multiplication of cylinders of engine and can not restrain vibration increase due to resonance. CONSTITUTION: Weights W1, W3 are installed in the vicinity of ends of a vibration control plate part, 1a of bed 1, while weight W2 in the vicinity of a central part thereof in such a manner that adjustment of each mass is free and ribs R are nipped respectively by them.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an anti-vibration structure on a pedestal for mounting an engine-driven device such as a power generator having an engine and a generator connected in series.

[0002]

2. Description of the Related Art Conventionally, in the case of supporting an engine-driven device such as a power generator, as a method of suppressing the vibration, for example, an anti-vibration member such as the actual open Sho 61-6097 or the actual open Sho 58-64513 is used. There is a method such as mounting a device or mounting a device on a substrate through a vibration isolating member, such as Japanese Utility Model Laid-Open No. 59-79646. In the case where the engine-driven device is mounted on the floor, in addition to mounting such a vibration-proof member, basically the rigidity of the floor itself is first increased (for example, it is reinforced with ribs, etc.), By increasing the natural frequency, the resonance frequency is avoided by providing a difference from the vibration frequency of the engine (caused by the unbalance between the rotating part and the reciprocating part and the maximum combustion pressure in the cylinder) to avoid resonance and increase the vibration. Had been deterred. (Unless the rigidity of the floor itself is increased in this way, even if the vibration-proof member is attached, the vibration will be large and the load on the engine-side parts will be heavy.)

[0003]

However, in recent years, the engine has been driven at a high speed and the number of cylinders has been increased, so that the vibration frequency generated by the engine becomes high, and the vibration frequency resonates with the natural frequency of the bed to cause vibration. The number of cases is increasing, and in order to avoid this resonance, increasing the rigidity of the base to further increase the natural frequency has reached the limit in manufacturing.

Further, in the case of a pedestal having ribs protruding to improve the rigidity, the ribs are the locations that receive the most force during vibration. If the ribs are heavily loaded, the ribs will break and the rigidity will increase. There is a risk that the anti-vibration effect will decrease.

Further, the natural frequency of the base for avoiding resonance must be changed according to the number of revolutions and the number of cylinders of the mounted engine. Conventionally, the base having various natural frequencies (rigidity) is required. Since several different types were prepared and the pedestal itself was changed depending on the type of engine to be installed, there was a problem in that the space for holding the pedestal was reserved because of the high cost.

[0006]

The present invention uses the following means in order to solve the above problems. That is, in a bed on which an engine-driven device is mounted, a vibration suppressing weight is attached near the free end or near the center of the device.

In addition, in a bed on which an engine-driven device is mounted, a vibration suppressing weight is attached in such a manner that a rib protruding from the bed is held.

In addition, a weight for vibration suppression is attached to a bed on which an engine-driven device is mounted so that the weight can be adjusted according to the type of engine to be mounted.

[0009]

Since the rigidity of the base is adjusted by attaching the weight, it is not necessary to manufacture a base with high rigidity. Also,
The motive force of the engine acts as a torsion moment and a bending moment, and the weight arranged near the free end suppresses the torsion moment and the weight arranged near the center suppresses the bending moment.

Further, by mounting the weight so as to sandwich the rib, the weight reinforces the rib, and on the other hand, the vibration due to the vibration of the weight is reduced, and the member for mounting the weight (for example, bolt) may be damaged. Absent.

Further, since the weight can be mounted by adjusting the mass according to the type of engine (rotation speed, number of cylinders), it is possible to mount various types of engines on one platform.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, the structure of the present invention will be described based on the embodiments shown in the accompanying drawings. FIG. 1 is a plan view of a base when weights are attached to both ends, FIG. 2 is a side view of the same, FIG. 3 is a plan view of base when weights are attached to both ends and around the center, and FIG. 4 is the same. A side view, FIG. 5 is a partial side cross-sectional view of a weight mounting portion, FIG. 6 is a side view of a bed with a power generator installed, FIG. 7 is a front view of the same engine side, and FIG. 8 is a screw of a bed with a power generator installed. FIG. 9 is a schematic side view of the engine side, FIG. 9 is a schematic front view of the generator side, and FIG. 11 is a schematic front view of the generator side.
Is a schematic view showing a mode of a torsional moment, and FIG. 12 is a schematic view showing a mode of a bending moment.

First, a construction in which a power generator is mounted on a floor will be described with reference to FIGS. 1 to 7. As shown in FIGS. 6 and 7, on the foundation B for installation, the left and right rail bases 7, 7 are arranged in parallel in the front-rear direction, and a plurality of front and rear rails are installed on the left and right rail bases 7, 7. Install the shaking members 5, 5 ... As shown in FIG. 7, the pedestal 1 has an open-up "U" shape in a front view. The left and right side plate portions 1 of the "U" shape
Horizontal vibration isolating plate portions 1a and 1a are extended to the left and right of b and 1b, and the vibration isolating members 5.5 are attached to the lower surface of each vibration isolating plate portion 1a.
The upper end of ... is the bolt 6.6 shown in FIG. 1 or FIG.
・ Installed in. Also, the side plate portions 1b and 1b
From the vertical ribs R (R
a to Rg) are projected.

On the left and right side plates 1b and 1b of the base 1, a front engine front pedestal 3F, an engine rear pedestal 3R, a generator front pedestal 4F, and a generator rear pedestal 4R are arranged in the front-rear direction. , The front and rear engine pedestals 3F and 3F and the rear engine pedestals 3R and 3R are fixed with flanges protruding from the left and right sides of the crankcase below the engine (engine) E, and
The lower part of the generator H, which is connected to the rear of the engine E, is connected to the left and right generator front pedestals 4F and 4F and the generator rear pedestals 4R and 4R.
The power generation device A is mounted on the pedestal 1 while being fixed on the 4R. In addition, as shown in FIGS. 1 and 3, fuel tanks T, T, and T are continuously provided below the engine E (see FIG. 1,
In FIG. 3, Ta is the lid of the fuel tank T), and these are the base 1
To the above-mentioned "U" -shaped portion, that is, on both sides of the side plate portion 1b.
The lower part is accommodated in b in a state of being surrounded by the bottom plate portion 1c.

Further, on the left and right anti-vibration plate portions 1a, 1a of the base 1, a weight W (W
1 ・ W2 ・ W3) can be attached. Each weight W
As shown in FIG. 5, 1-W2-W3 are each formed by accumulating several weight plates Wa-Wa.
The mass is adjusted by the cumulative number of sheets a. Each weight plate Wa has a mass that can be held by hand, and can be easily carried by hand.
Each of the weights W1, W2, W3 is directly tightened on the vibration-proof plate portion 1a without any clearance by means of a bolt 6 for screwing the vibration-proof member 5 extending upward. The anti-vibration plate portion 1a is a portion that protrudes to the outermost side in the base 1, and the work of attaching and detaching the weight W is easy.

Explaining the mounting position of the weight W, the weight W1 is provided between the ribs Ra and Rc and the weight W2.
Is sandwiched between the ribs Rd and Rf, and further, the weights W1, W2, and W3 are provided with notches, and the ribs Rb, Re, and Rg are sandwiched in the respective notches. As described above, by attaching each weight W integrally with the rib R, the durability of the rib R itself is improved, and the rigidity improving effect of the pedestal 1 is increased.
Since the rolling caused by the vibration is eliminated, the bolt 6 that is screwed to the vibration isolating plate portion 1a is not loosened or damaged, and the bolt 6 is firmly screwed to the vibration isolating plate portion 1a. , The weight W does not newly generate vibration, and the weight W is firmly integrated with the vibration-proof plate portion 1a, that is, the base 1, to further improve the rigidity of the base 1.

As described above, the weight W is attached to the base 1 so that the natural frequency of the base 1 resonates with the vibration generated by the drive of the engine E and the natural frequency is not increased. This is to lower the That is, the natural frequency of the bed 1 is significantly lower than the frequency of the engine E so that resonance caused by the approximation of the frequency is not generated.

Here, the relationship between the mass of the weight W attached to the floor 1 and vibration will be described. First, the engine E produces reciprocating motion of a piston, rotation of a crank shaft, and further, a vibrating force having different motion directions such as cylinder pressure.
The natural vibration of the base 1 is combined with this, so that a torsion moment and a bending moment act on the base 1. The vibration modes of the pedestal 1 caused by each of the torsional moment and the bending moment are M1 and M2 in FIG. 8 in a side view, respectively. In addition, the torsional moment includes a lateral force, and as shown in FIGS. 9 and 10, the platform 1 and the engine E of the power generator A are tilted laterally (E ′ in the drawings). Conversely, since the generator H does not move with respect to the lateral force of the engine E, twisting occurs. Here, the center N1 of the torsional moment is such that the base 1 is not fixed to the engine E and the generator H, and the connecting portion 2 between the engine E and the generator H where the torsion is most likely to occur is 2
Bending moment, on the other hand, is related to vertical movement in the entire front-back width of the base 1,
The center N2 that works most is the front-rear center of the bed 1.

The vibration mode of the pedestal 1 due to the torsional moment M1 corresponds to the vibration of the shaft having rotating disks at both ends shown in FIG. Here, if the length of this axis (corresponding to the entire length in the front-rear direction in the bed 1) is k and the moments of inertia of the disks at both ends are J ₁ and J ₂ , respectively, the angular frequency ω ₁ (rad / s ) Is expressed as in Equation 1.

[0020]

[Equation 1]

If the masses and radii of the disks at both ends are m and r, the moments of inertia J ₁ , J ₂ = m · r.
Therefore, the angular frequency ω ₁ is expressed as in Equation 2.

[0022]

[Equation 2]

Therefore, it can be seen that the angular frequency ω ₁ changes when the mass m changes. Therefore, in the vibration due to the torsional moment, the natural frequency of the base 1 and the engine starting frequency can be shifted by adjusting the mass placed on both ends of the base 1. Also, if it can be shifted, there is no resonance, so vibration due to resonance can be suppressed. Therefore, as shown in FIGS. 1 and 2, the weights W1 and W3 are attached to both ends of the base 1.
The vibrations due to the torsional moment are suppressed by attaching the right and left sides.

On the other hand, the vibration mode due to the bending moment is
It can be likened to the vibration of a massless beam having a concentrated mass whose both ends are simply supported as shown in FIG. Further, in the state where the weights W1 and W3 are attached to both ends as shown in FIG. 1, this mode becomes more remarkable. If the concentrated mass is m and the length of the beam is L, the angular frequency of vibration due to the bending moment ω ₂ (rad /
s) is expressed as in Equation 3, and it can be seen that the angular frequency ω ₂ decreases as the concentrated mass m increases.

[0025]

[Equation 3]

This concentrated mass ω ₂ is applied to the center of the beam. Therefore, in the base 1, it covers the front and rear central portions thereof. In the case of the torsional moment, since the torsion is applied to the base 1 below the connecting portion 2 between the engine E and the generator H as described above, the engine E and the generator H are directly connected to the base 1. Although it is not affected by twisting, the vibration due to the bending moment is concentrated in the central portion of the base 1, and the connecting portion 2 is not always located at this portion. A
Then, the connecting portion 2 is closer to the generator H side than the central portion. Therefore, the abdomen of the engine E is affected by the bending of the base 1. This bending moment has a weight W1
It is further emphasized in the state where W3 is attached (both ends of the base 1 are suppressed). Therefore, in the vicinity of the central portion where the concentrated mass m is applied, by attaching the weight W2 as shown in FIGS. 3 and 4, the vibration due to the bending moment can be adjusted.

As described above, even if the rigidity of the entire pedestal 1 is not increased, vibration due to a torsional moment or a bending moment can be effectively provided by attaching the weight W near the end or center of the pedestal 1. Since it can be suppressed, the weight and cost of the base 1 itself can be reduced.

Further, the driving mode of the engine E differs depending on, for example, the number of cylinders thereof, and the output frequency of the generator differs (for example, in order to generate a current of frequency 50 Hz in eastern Japan and frequency 60 Hz in western Japan). The engine speed must be changed according to. Thus, when the driving mode of the engine is different, the frequency of the engine also fluctuates, and accordingly, the rigidity of the base 1, that is, the mass of the weight W attached to the base 1, must be changed.
Further, since the ratios of the torsional moment and the bending moment are also different, it is necessary to adjust the position of the weight W where vibration should be effectively suppressed. To adjust the placement position,
This is dealt with by selecting which of W1, W2 and W3 is attached or removed, and the weight W
The mass adjustment of is handled by adjusting the cumulative number of weight plates Wa in each weight W. This adjustment may be performed by visually observing the vibration condition or by measuring with a vibrometer,
Alternatively, the mounting position of the weight W and the mass may be calculated by FEM analysis.

An example of the procedure for adjusting the mounting position of the weight and the mass will be described. First, start engine E,
After operating the generator H, both ends of the base 1 (weight W1
-One weight plate Wa is attached to each W3 mounting position) to suppress vibration due to a torsion moment. The state of vibration is visually observed or measured by a vibrometer, and if the vibration is large, one weight plate Wa is further stacked. This vibration measurement and the work of attaching the weight plates Wa are repeated to determine the number of the weight plates Wa when the vibration becomes the smallest. Next, also in the vicinity of the center of the base 1 (position where the weight W2 is attached), the vibration measurement and the attachment of the weight plates Wa are similarly repeated to determine the number of the weight plates Wa when the vibration becomes the smallest. In addition to adjusting the mass based on the vibration measurement in this way, a method of previously calculating the mass and the like by FEM analysis and then attaching the weight W at an appropriate mass and attachment position is also conceivable.

[0030]

Since the present invention is configured as described above, it has the following effects. That is, since it is configured as in claim 1, the rigidity of the base can be adjusted by attaching weights, and it is not necessary to manufacture a high-rigid base by, for example, increasing ribs, increasing mass and thickness. In addition, the cost can be reduced, and resonance suppression can be effectively performed for a high-speed, multi-cylinder type engine that could not be realized by the bed. The vibration of the pedestal includes that due to the torsional moment and that due to the bending moment, but the vibration due to the torsional moment is arranged near the center with the weight arranged near the free end. Vibration due to bending moment is effectively suppressed by the weight. As described above, by disposing the weights in consideration of the type of vibration, it is possible to effectively suppress the vibration without applying a mass to the whole.

Further, according to the second aspect, by attaching the weights so as to sandwich the ribs on the floor, the weights reinforce the ribs to enhance the durability of the ribs, while the vibrations of the weights also cause vibrations. Therefore, the weight mounting member (for example, bolt) is not damaged. Therefore, the weight, the ribs, and the base are further integrated to surely increase the rigidity.

Furthermore, as described in claim 3, since the weight can be mounted by adjusting the mass depending on the type of engine (rotation speed, number of cylinders), it is possible to mount various types of engines on one platform. The cost can be reduced.

[Brief description of drawings]

FIG. 1 is a plan view of a base with weights attached to both ends.

FIG. 2 is a side view of the same.

FIG. 3 is a plan view of the base when weights are attached to both ends and the vicinity of the center.

FIG. 4 is a side view of the same.

FIG. 5 is a partial side sectional view of a weight mounting portion.

FIG. 6 is a side view of a pedestal equipped with a power generator.

FIG. 7 is likewise a front view of the engine.

FIG. 8 is a schematic side view showing a vibrating surface due to a torsional moment and a bending moment of a pedestal equipped with a power generator.

FIG. 9 is likewise a schematic front view of the engine side.

FIG. 10 is a schematic front view of the generator side.

FIG. 11 is a schematic view showing a mode of a torsional moment.

FIG. 12 is a schematic view showing a mode of bending moment.

[Explanation of symbols]

 1 Floor 1a Anti-vibration plate 1b Side plate 1c Bottom plate R rib W Weight Wa Weight plate A Generator E Engine T Fuel tank H Generator

Claims (3)

[Claims] 1. An anti-vibration structure for an engine floor, wherein a vibration-suppressing weight is attached near a free end or near a central portion of the apparatus in a bed on which an engine-driven device is mounted. 2. A base for mounting an engine-driven device, wherein a vibration-suppressing weight is attached in such a manner that a rib protruding from the base is sandwiched therebetween. Swing structure. 3. An anti-vibration structure for an engine floor, wherein a weight for vibration suppression is attached to a bed on which an engine-driven device is mounted so that the weight can be adjusted according to the type of engine installed. .