JPH0119201B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to improving the ballast mounting structure of fluorescent lamp equipment, and particularly aims to sufficiently reduce the noise generated during lighting so that it can be used without any trouble even in a very quiet room. It is something to do.

The ballast mounting part of conventional fluorescent lamp equipment is the
It has a structure as shown in FIGS. That is, the ballast 3 is attached to the case 2 that supports the fluorescent lamp 1 by tightening screws 5 through rubber gaskets 4. However, with this mounting structure, not only is the vibration and noise isolation effect transmitted from the ballast 3 to the case 2 unsatisfactory, but this effect changes depending on the tightening condition of the screws, making it difficult to manage work during assembly. There are some difficult things. Furthermore, noise from conventional fluorescent lighting fixtures often becomes a problem in very quiet rooms, such as in bedrooms late at night. In order to eliminate or alleviate these problems, the following points need to be solved.

(1) Improved vibration and soundproofing effects.

(2) Does not require a high level of skill during assembly.

(3) Can be used without problems even in a quiet room.

The present invention was made in view of the above circumstances, and by attaching the stabilizer to the case using an elastic support plate that satisfies specific conditions, the vibration-proofing and sound-proofing effects are greatly improved, and the tightening is also possible using screws. It is an object of the present invention to provide a fluorescent lamp fixture having a structure that is sufficiently secured by tightening and can be assembled efficiently.

The details of the present invention will be explained below with reference to FIG. 3 showing one embodiment thereof. In the figure, numeral 3 denotes a ballast, which has a transformer inside, and vibrations and noise are generated by the vibration of the laminated plate due to its magnetic vibration and electromagnetic attraction force. The predominant excitation frequency is twice the power supply frequency. When the excitation force having this original frequency is directly transmitted to the case 2, the case vibrates and generates noise. Therefore, it is necessary to have a structure that blocks this transmission path, and this structure will be explained next. Reference numeral 6 designates elastic support plates, each elastic support plate is capable of bending and deforming in the direction of gravity, and one end thereof is fixed to both ends of the stabilizer 3 by tightening screws 7, etc., and the other end of each elastic support plate is is fixed to the case 2 by tightening with screws 8, etc., and the stabilizer 3 is elastically supported by the case 2 from both sides.

In order to improve the vibration-proofing effect of the elastic support plate 6 described above, it is necessary to select its shape and dimensions so as to satisfy the following conditions.

bt ³ /l ³ ≦2π ² /E・Gf _s ²・W where f _s : Power frequency (Hz) W : Ballast weight (Kg) l : Effective length of elastic support plate (cm) b : Elastic support Width of plate (cm) t: Thickness of elastic support plate (cm) E: Young's modulus (Kg/cm ² ) G: Gravitational acceleration (cm/s ² ) The reason will be explained below. The most powerful source of noise and vibration in fluorescent lighting equipment is the excitation force caused by the magnetic vibrations and _{electromagnetic} attraction of the ballast 3; The excitation force having a frequency near 2·f _s ) dominates. For example, when the power supply frequency (f _s ) is 50Hz, the vibration mode generated in the ballast 3 is as shown in the curve diagram in Figure 4, with the acceleration level [Grms] on the vertical axis and the frequency [Hz] on the horizontal axis. Power frequency ( _fs )
The acceleration level value concentrates and becomes large in a frequency band around 100Hz (2f _s ), which is twice that of , and further increases near the harmonics (4f _s , 8f _s . . . ). For this reason, among the vibrations generated in the ballast 3, the vibration components having a frequency that is twice or more the power supply frequency (f _s ) are absorbed by the elastic support plate 6 and are prevented from being transmitted to the case 2 side. This makes it possible to suppress the vibrations generated in step 2 and reduce noise.

For purposes of explanation, the vibration transmission system consisting of the instrument case 2, stabilizer 3, and elastic support plate 6 will be replaced with a spring-mass system with one degree of freedom as shown in FIG.

In Fig. 5, B is the foundation corresponding to the case 2, K is the spring corresponding to the elastic support plate 6 that connects the case 2 and the stabilizer 3, M is the weight having a mass equivalent to that of the stabilizer 3, and C is the elastic This is an attenuator equivalent to the attenuation component of the support plate 6. Here, F ₀ is the excitation force generated in the ballast 3,
F _B is the transmission force that is the force that the excitation force F ₀ exerts on the foundation B via the spring K and the damper C, k is the spring constant of the spring K, m is the mass of the stabilizer, and c is the damper C
Let the damping constant be .

Generally, in such a spring-mass system with one degree of freedom, the influence of an external force applied to the mass (M) on the base (B) is evaluated using the absolute transmissibility. In the above vibration transmission system, this absolute transmissibility is calculated by the excitation force F ₀ generated in the stabilizer 3 and the force exerted by this excitation force F ₀ on the foundation (B).
It is expressed as a ratio to F _B. The formula for calculating the absolute transmissibility is shown in Equation (2) below.

Here, T _A is the absolute transmissibility, ω is the angular frequency of the excitation force F ₀ (in rad/s), ω _o is the natural angular frequency of the above spring-mass system (in rad/s), and ζ is The damping constant c of the attenuator C is defined as the critical damping constant Cc (Co=2√
It is the damping ratio obtained by dividing mk (unit: Kgf·s/cm). Note that the excitation force F ₀ is given a scalar value by F _A ·Cosωt (F _A is the amplitude).

When the value of the absolute transmissibility T _A obtained by this equation (2) is “1”, the excitation force F ₀ generated in the ballast 3
is directly transmitted to the foundation B via the elastic support plate 6. Therefore, if the value of the absolute transmissibility T _A is smaller than 1, the excitation force F ₀ is the foundation (B)
Since the proportion of vibration transmitted to the elastic support plate 6 is reduced, the vibration-proofing effect of the elastic support plate 6 can be obtained.

Next, this equation (2) is a general equation, and since steel (for example, iron) is generally used for the elastic support 6 that supports the stabilizer 3, this damping constant c is a very small value (C= 0.0002~3), so the damping ratio ζ is ζ≒0
From equation (2), we obtain equation (3) shown below.

That is, it can be seen from equation (3) that in order to reduce the value of the absolute transmissibility T _A , the natural angular frequency ω _o of the spring-mass system should be made smaller than the angular frequency ω. Here, the natural angular frequency ω _o is ω _o =2πf ₀ …(4)
(However, f ₀ is the natural frequency of the above spring-mass system), and the angular frequency ω is ω = 2πf _o ... (5) (however, f _o is the frequency of the excitation force F ₀ ), so It can be seen that if the natural frequency f ₀ is made smaller than the frequency f _o , the value of the absolute transmissibility T _A becomes smaller in the same way. Also, the
The relationship between the value of the absolute transmissibility T _A obtained by substituting equations (4) and (5) into equation (2), the frequency f _o , and the natural frequency f ₀ is shown by the curve in Figure 6. As shown in the figure, when the frequency f _o and the natural frequency f ₀ have the relationship f _o = f ₀ , the absolute transmissibility T _A is maximum, and when the relationship f _o = √2 f ₀ , the absolute The value of the transmissibility T _A is 1, and when there is a relationship of f _o >√2f ₀ , the absolute transmissibility T _A has a characteristic that T _A <1. This characteristic can be expressed as the following equation (6).

T _A = | 1/1 - (f _o / f ₀ ) ² |......(6) Therefore, the condition where the value of the absolute transmissibility T _A is smaller than 1, that is, at least the elastic support plate 6 has a vibration isolation effect. As a condition for obtaining , the natural frequency f ₀ of the above spring-mass system may be determined so as to satisfy the relationship f _o >√2f ₀ .

Note that this is a general anti-vibration theory. Therefore, as mentioned above, the ballast 3 has the power supply frequency f _s
An excitation force _{F 0} with a frequency _{f o} consisting of a frequency band near 2f _s , which is twice the frequency _of Since an excitation force F ₀ is generated, the frequency f _o becomes the frequency 2f _s
It is necessary to determine the natural frequency f ₀ of the spring-mass system so that the value of the absolute transmissibility T _A of the excitation force F ₀ is sufficiently smaller than 1.

Here, the difference in the level at which humans perceive noise to be less than before is generally said to be about 5 dB, so in Case 2, the noise was reduced by reducing the generated sound by 5 dB or more. Become. In other words, the magnitude of the sound generated from the case 2 changes in proportion to the magnitude of the vibration generated as a result of the excitation force F ₀ generated from the stabilizer 3 being transmitted to the case 2 via the elastic support plate 6. , the value of the absolute transmissibility T _A is
By reducing the noise by an amount corresponding to 5 dB, the sound generated in case 2 can be reduced by 5 dB.

Now, the noise when the value of absolute transmissibility T _A is 1 is
The value of the absolute transmissivity T _A that reduces the noise level by 5 dB or more from 0 dB is calculated using the following equation (7).

10logT _A −5dB (7) The value of the absolute transmissibility T _A that satisfies equation (7) is T _A 1/3. Therefore, the value of the absolute transmissibility T _A is T _A 1/
If it is set to 3, the noise generated in case 2 will be reduced by 5 dB or more compared to when the value of absolute transmissibility T _A is 1.

As is clear from Equation (6) or Figure 6, the frequency f _o when the value of the absolute transmissibility T _A is T _A 1/3 is twice the natural frequency f _o of the above spring-mass system ( 2f ₀ ) or more, the frequency f _o is the power supply frequency of the ballast 3.
Since it is twice f _s (2f _s ), the natural frequency f ₀ of the spring-mass system needs to satisfy the condition of equation (8) shown below.

f ₀ ≦ f ₅ ………(8) By setting the natural frequency f ₀ to satisfy the condition of Equation (8), the value of the transmission T _A of the noise generated from Case 2 can be reduced. It can be lowered by 5dB or more compared to the case of 1.

That is, by satisfying this condition,
This results in extremely excellent vibration and soundproofing effects. Therefore, the material of the elastic support plate 6 for mounting the ballast 3 of the fluorescent lamp fixture should be designed so as to satisfy the formula (6).
All you have to do is decide on the size limits, etc. For example, in the case of a fluorescent light fixture used at a power supply frequency f _s = 50 Hz, the minimum frequency f = 100 Hz, and the natural frequency is 1/2 of this minimum frequency f or less, that is, f ₀ It is good if it is ≦50Hz. For comparison, in many fluorescent light fixtures in which conventional ballasts are attached via rubber gaskets, f ₀ =approximately 93 Hz.

Next, a specific method for determining this natural frequency f ₀ will be explained in detail. First, the ballast M installed in the fluorescent lamp fixture is fastened to the leaf spring K with a screw, so if we ignore the strain angle at this screw part and approximate it, we can see that both ends are fixed as shown in Figure 7. Considering it as a centrally concentrated mass with a stiffness H, the natural frequency f ₀ is expressed as (9)
Calculate using the formula.

Here, k: constant of the elastic support plate spring Kg/cm G: gravitational acceleration 980 cm/S ² W: load (ballast weight) Kg The gravitational acceleration is known, and the ballast weight will be known once the model is determined.

By calculating the unknown k from the above conditions, the dimensions of each part of the elastic support plate 6 shown in FIGS. 8 and 9 can be determined.

k=192EI/(2l) ³ ......(10) where I: Secondary moment of area bt ³ /12cm ⁴ E: Young's modulus (iron 2.1×10 ⁶ ) Kg/cm ² l: Effective length of elastic support plate cm b: Width of the elastic support plate cm t: Thickness of the elastic support plate cm First, rewriting equation (9), k = (2πf ₀ ) ²・W/G ...... (9') This (9 ′) The following equation can be obtained from the condition of equation (8) and equation (10).

k=192EI/(2l) ³ = (2πf ₀ ) ² ×W/G≦(2πf _s ) ² ×W/G (11) If we organize this by the dimensions of each part of the elastic support plate 6, we also get ( 10) When calculating by substituting I=bt ³ /12 for I in formula, k=192EI/(2l) ³ = 192E/8l ³・bt ³ /12=bt ³ /l ³・2
E ......(10') Also, if we focus on the above k, there is a relationship of equation (10') = equation (11), and using this to summarize as bt ³ /l ³ , bt ³ /l ³ ≦ 4π ² fs ² /2E・W/G=2π ² /E・Gfs ²・
W Equation (1) is thus derived.

If this is further summarized into an equation for the case where the elastic support plate is formed of an iron plate (by substituting the Young's modulus of iron into the Young's modulus of E), it becomes as follows.

As an example, f _s = 50 Hz, W = 1.5 kg, the elastic support plate is made of iron plate, its thickness t = 0.06 cm, and the width b
= 1 cm, the length l is as follows.

When f ₀ ≦50Hz, b=1cm, t=0.06
cm, it is sufficient to set l≧1.82cm. In this way, assuming two of b, t, and l, the remaining one is determined.

The shape of the elastic support plate is not limited to the rectangular shape shown in the figure, but may be other shapes such as a trapezoid. In this case, b, t, and l can be satisfied by taking average values.

In the above embodiments, the elastic support plate was exemplified in the case where a plate material prepared separately from the case was fixed at one end with screws, etc. However, the elastic support plate is not limited to this, and as shown in FIG. A plate member may be formed by cutting and raising the side wall of the case so that one end is integrally fixed to the case, and in this case, a member for fixing one end of the elastic support plate to the case is unnecessary.

Next, the noise of the conventional rubber seal support type and the present invention's elastic support plate type fluorescent lamp fixtures will be estimated at 60%.
Figure 11 shows a comparison of 1/3 octave frequency analysis for the results measured at a distance of cm. As can be seen from this figure, in each frequency band, the noise of the fluorescent light fixture of the present invention is approximately 15 phon lower at the peak value than that of the conventional type, and the fluorescent light fixture of the present invention has a lower soundproofing effect than the conventional type. The noise level is reduced by about 9 phons compared to .

As is clear from the above description, in the present invention, the elastic support plates are attached in a state that allows bending deformation in the direction of gravity, thereby elastically supporting the stabilizer, and each elastic support plate has its own dimensions. Since the selection was made within the limited range of Since the frequency is less than half of twice the frequency, the vibration generated by the ballast is absorbed better than the elastic support plate, resulting in extremely excellent vibration and soundproofing effects.Furthermore, the ballast is simply attached to the elastic support plate. It has the advantage of only needing to be fixed, does not require a high level of skill for assembly, and can greatly improve the efficiency of assembly work, and has great industrial value.

[Brief explanation of drawings]

Figure 1 is a partially cutaway perspective view of a conventional fluorescent lamp fixture.
FIG. 2 is a sectional view of the ballast mounting part, FIG. 3 is a sectional view of the ballast mounting part of the fluorescent lamp apparatus of the present invention, and FIG.
The figure is a curve diagram showing the acceleration spectrum of a fluorescent lamp fixture, Figure 5 is an explanatory diagram of approximate analysis of the vibration transmission system, and Figure 6
The figure is a curve diagram showing the relationship between the natural vibration frequency (f ₀ ) and the transmissibility ( _TA ), Figure 7 is an explanatory diagram for approximate analysis of the vibration transmission system, and Figure 8 is the fluorescent lamp fixture of the present invention. a top view showing the dimensions of the elastic support plate for the ballast;
Fig. 9 is a partially cutaway side view of Fig. 8, Fig. 10 is a sectional view of main parts showing another embodiment of the present invention, and Fig. 11 compares the noise levels of the conventional type and the fluorescent lamp fixture of the present invention. FIG. 1... Case, 3... Stabilizer, 4... Rubber packing, 6... Elastic support plate.

Claims (1)

[Scope of Claims] 1. A pair of elastic support plates made of a plate material separate from the case and having one end fixed to a case supporting the fluorescent lamp, or the case such that one end is integrally fixed to the case. A pair of elastic support plates formed by cutting and raising a wall are attached to the other end near both ends of the stabilizer in a state where they can be bent and deformed in the direction of gravity, and the elastic support plates satisfy the following conditions. Fluorescent lighting fixtures characterized by: bt ³ /l ³ ≦2π ² /E・Gf _s ²・W where f _s : Power frequency (Hz) W : Ballast weight (Kg) l : Effective length of elastic support plate (cm) b : Elastic support Plate width (cm) t: Thickness of elastic support plate (cm) E: Young's modulus (Kg/cm ² ) G: Gravitational acceleration (cm/s ² )