JPS6117132B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a discharge lamp ballast that reduces vibration noise caused by magnetostrictive vibrations and leakage magnetic flux.

Conventionally, in ballasts for discharge lamps, vibration caused by magnetostrictive vibration or leakage magnetic flux of the laminated steel plate used in the ballast body is transmitted through the ballast case or the screws, rivets, etc. that attach the ballast case. ,
The problem was that the noise was transmitted to the lamp frame and generated noise. Therefore, it is common practice to interpose a rubber gasket or the like between the ballast case and the lamp frame to absorb the vibrations generated by the ballast.
Although this method has a large noise reduction effect, it is not always satisfactory as it varies slightly depending on the hardness and thickness of the rubber packing or the method of tightening the screws when installing the ballast.

The present invention has been made in view of the above circumstances, and includes providing elastic mounting pieces at both ends of a ballast mounting case that houses the ballast main body, and adjusting the length, plate thickness, and width dimensions of the elastic mounting pieces to the ballast. The system is set so that the natural vibration frequency of the system including the main body and the ballast mounting case is less than twice the excitation commercial frequency of the ballast, and the vibration generated from the ballast is transmitted to the lamp frame. It is an object of the present invention to provide a discharge lamp ballast that prevents

Embodiments of the present invention will be specifically described below with reference to the drawings.

In the figure, 1 is the stabilizer body, 2 is the stabilizer body 1
This is a ballast mounting case that stores the ballast. Notches 3, 3 are provided at both ends of the ballast mounting case 2, and elastic mounting pieces 4, 4 are provided integrally with the ballast mounting case 2. Mounting holes 5, 5 are bored at the tips of the elastic mounting pieces 4, 4, and bolts 8, 5 are inserted into the lamp frame body 6 through elastic spacers 7, as shown in FIG.
and is fixed by a nut 9.

Incidentally, the length, plate thickness, and width dimensions of the elastic mounting pieces 4, 4 are set as follows. Now, considering the vertical vibration of the ballast main body 1 and the ballast mounting case 2 attached to the lamp frame 6, it becomes equivalent to a spring mass system with one degree of freedom shown in FIG. Therefore, assuming that the external force Fo cos ωt acts on the mass m, the force F _B transmitted to the lamp frame 6 is expressed as F _B = _TA ·Fo (1).

Note that T _A is the absolute transmissibility. The absolute transmissibility T _A in a spring mass system with one degree of freedom is given by the following equation.

Here, ωn: √natural vibration rate, ω: forced vibration rate, ζ: damping ratio C/Cc, C: damping constant of leaf spring, Cc: critical damping constant 2√, k: spring constant. Further, the ballast body 1 is attached to the lamp frame body 6 via iron elastic attachment pieces 4, 4.
The damping constant C is very small at 0.0002 to 0.0003, and the damping ratio ζ is approximated to zero, so equation (2) is becomes. Therefore, in order to reduce T _A , that is, to reduce the transmitted force F _B , the natural vibration rate ωn should be made smaller than the forced vibration rate ω.

Further, the ballast main body 1 is fixed to the lamp frame body 6 by bolts 8 and nuts 9 via the ballast mounting case 2 and elastic mounting pieces 4, 4.
As shown in the figure, the ballast main body 1 is fixed to the center of a leaf spring, and both ends of the ballast main body 1 are fixed to the lamp frame body 6, which is similar to a beam structure.

Therefore, the natural frequency ωn of this system is given by the following equation.

However, E: Young's modulus 2.1×10 ⁶ Kg/cm, g: gravitational acceleration 980cm/sec ² , ₁ = ₂ length of leaf spring,
t: Length of leaf spring (cm), b: Width of leaf spring (cm),
W: Stabilizer weight (Kg).

Here, ωn = 2πn (n is the natural vibration frequency of the system), so the natural vibration frequency n of the system is becomes.

By the way, the ballast body 1 vibrates at the excitation commercial frequency, that is, the multiple harmonic frequency whose fundamental frequency is twice the power supply frequency, due to magnetostrictive vibrations, leakage magnetic flux, etc., and these vibrations are transmitted to the lamp frame 6, etc. It is known that the noise is transmitted. Therefore, if the power supply frequency _{is 0} , the frequency components that make up this noise are 2 ₀ , 4 ₀ , 8 ₀ . . . 2
ⁿ⁰ _. Furthermore, the condition for reducing the transmission of vibrations acting on the ballast body 1 to the lamp frame body 6 is as described above, the natural vibration rate ωn of the system < forced vibration rate ω
It is. Since ω=2π, the natural vibration frequency n of the system is n<2 ₀ , 4 ₀ , 8 ₀ , ...2 ⁿ ₀ , and in order to reduce the transmission force of all frequency components that make up the noise, This means that the natural vibration frequency n may be set to be smaller than the fundamental frequency 2f ₀ . In other words All you have to do is satisfy.

In equation (5), Young's modulus E, gravitational acceleration g, and ballast weight W are known, so the length, thickness, and width of the elastic mounting pieces 4, 4 satisfy the conditions of equation (5). It is set to do so.

With such a configuration, magnetostrictive vibrations and vibrations due to leakage magnetic flux that vibrate the ballast body 1 can be suppressed by the elasticity provided at both ends of the ballast mounting case that houses the ballast body 1. The light is effectively attenuated by the mounting pieces 4, 4, and is not transmitted to the lamp frame 6. Also, elastic mounting pieces 4, 4
Since an elastic spacer 7 is interposed between the ballast body 1 and the lamp frame 6, vibrations of the ballast main body 1 are further absorbed and not transmitted to the lamp frame 6. Therefore, this type of noise generated from discharge lamps can be extremely effectively prevented. The elastic mounting pieces 4, 4 provided at both ends of the ballast mounting case in the present invention may be integrally protruded from both ends of the ballast mounting case 20, as shown in FIG. Furthermore, in this embodiment, the elastic mounting piece 4 is attached to the lamp frame 6 using a rubber bushing 25 provided with a groove 24 that fits into the mounting hole 5 formed in the elastic mounting piece 4, as shown in FIG. may be interposed between the elastic mounting piece 4 and the lamp frame body 6 and fixed with bolts 27 and nuts 28. In this way, not only vertical vibration but also torsional moment and lateral vibration of the mounting portion can be prevented.

As described above, the present invention provides elastic mounting pieces at both ends of the ballast mounting case that houses the ballast main body, and the length, plate thickness, and width dimensions of the elastic mounting pieces are set to the ballast and the ballast main body. Since the natural vibration frequency of the system including the lamp mounting case is set to a value less than twice the excitation commercial frequency of the ballast, the ballast body is transmitted to the lamp frame via the elastic mounting piece. magnetostrictive vibrations or vibrations caused by leakage magnetic flux that occur in
It is possible to provide a discharge lamp ballast that can extremely effectively prevent noise generated from discharge lamps.

[Brief explanation of the drawing]

Fig. 1 is a perspective view showing one embodiment of the present invention, Fig. 2 is a sectional view showing the installed state of the embodiment, Fig. 3,
FIG. 4 is a model diagram of the vibration system, FIG. 5 is a perspective view showing another embodiment of the present invention, and FIG. 6 is a sectional view showing another mounting state of the ballast mounting case. 1... Stabilizer main body, 2... Stabilizer mounting case,
4...Elastic mounting piece.

Claims (1)

[Claims] 1. An elastic mounting piece is provided at both ends of the ballast mounting case that houses the ballast body, and the length, plate thickness, and width dimensions of this elastic mounting piece are determined based on the natural vibration of the system including the ballast body and the ballast mounting case. A discharge lamp ballast, characterized in that the frequency is set to a value not more than twice the excitation commercial frequency of the ballast.