JPH047559Y2 - - Google Patents

Description

[Detailed explanation of the idea]

[Field of Application of the Invention] The present invention relates to a discharge lamp having an explosion-proof protection structure for use in explosion-proof lighting equipment. [Background of the invention] Conventionally, a fluorescent lamp with the structure shown in Figure 2 has been used as a discharge lamp with an explosion-proof protection structure used in explosion-proof lighting equipment installed in places where flammable gas is present. . That is, in a normal fluorescent lamp 1, both tube ends near where the electrodes are located are covered with an aluminum pipe 2, a lamp nipple 3 is glued to both tube ends, and a fluorescent lamp including a part of the lamp nipple 3 and the aluminum pipe is formed. The entire length of the lamp is hermetically sealed with multiple layers of transparent flame-retardant plastic. The coating layer is a first coating layer 4 in contact with the tube wall of the fluorescent lamp 1.
For example, an uneven groove 5 is provided along the length direction of the fluorescent lamp 1 to maintain a predetermined amount of air between the tube wall of the fluorescent lamp 1 and the plastic layer below the second coating layer 6. The outer periphery is protected. When the discharge lamp having the above structure is installed in a lamp socket of an explosion-proof lighting equipment, the lighting equipment is constructed so that the charging portion of the lighting equipment remains completely separated from the environment surrounding the lighting equipment. If the glass tube of the fluorescent lamp is damaged during lighting due to an external impact, the first
A certain amount of air held between the coating layer 4 and the glass tube wall enters the broken lamp, instantly stopping the discharge and lowering the temperature of the electrodes. Prevents ignition and explosion. However, the aluminum pipe protects the electrode part of the fluorescent lamp 1 from mechanical shock, protects the coating layer from the influence of ultraviolet rays at high temperatures, and prevents the coating layer from coming into contact with the electrode in the event of breakage of the fluorescent lamp 1. has good thermal conductivity, and since its surface is covered with the transparent plastic coating, it has poor heat dissipation, which increases the temperature at both tube ends of the fluorescent lamp. Tables 1 and 2 show the measurement results of the temperature rise of the plastic coating layer under lighting conditions. Table 1 shows the measurement results at 40W, and Table 2 shows the measurement results at 20W, both of which are for rapid-start type fluorescent lamps.

【table】

[Purpose of invention]

The object of the present invention is to provide an explosion-proof discharge lamp for lighting equipment that can maintain a low temperature of the plastic coating covering the tube wall for explosion-proof protection. [Summary of the invention] In order to achieve the above object, the discharge lamp according to the invention is an explosion-proof lighting device, which is equipped with a nickel lamp at each end to be attached to a lamp socket, and a glass tube between them is coated with a transparent protective coating. In a discharge lamp for an appliance, the glass tube near the electrodes at both ends is covered with a heat insulating material made of asbestos or ceramic, and the entire length of the discharge lamp including the heat insulating material is covered with a transparent and at least flame-retardant material from a part of each lamp nipple. The temperature of the plastic coating is kept low by trapping a predetermined amount of air between the plastic coating and the glass tube wall to provide an airtight covering. [Embodiment of the invention] Next, an embodiment of the invention will be described with reference to the drawings. FIG. 1 is a partial sectional view showing one end of an embodiment of a discharge lamp according to the present invention. In FIG. 1, lamp nipples 3 screwed into lamp sockets (not shown) are arranged at both tube ends of a discharge lamp 1, and the glass tubes near both electrodes of the discharge lamp 1 are respectively covered with asbestos 7. lamp nipple 3
The entire length of the discharge lamp 1 including the surface of the asbestos 7 is covered with a first coating layer 4 of transparent flame-retardant vinyl chloride having a plurality of uneven grooves 5, and the surface is further covered with a transparent first coating layer 4 of vinyl chloride having a flame retardant property. It is airtightly covered with a second coating layer 8 and a third coating layer 9 of vinyl chloride, each of which has a slightly different composition. The first coating layer 4 is provided with a plurality of uneven grooves 5 along the tube wall of the discharge lamp 1, and the grooves 5 have enough grooves to immediately stop the discharge when the first coating layer 4 penetrates into the glass tube of the discharge lamp 1. It contains a large amount of air, and its surface is hermetically covered and protected with a flexible and tough protective coating consisting of the second and third coating layers 8 and 9. The protective coating consisting of the first, second, and third coating layers has high resistance to external impact, has a tensile strength of 200 kg/cm ² or more, and is durable at the end of the lamp life.
It has a growth rate of over 140%. When a discharge lamp with the above structure is installed in the lamp socket of an explosion-proof lighting fixture, the live part is completely isolated from the surrounding environment, and in the event that the glass of the discharge lamp 1 is damaged by an external impact, etc. In this case, the air contained in the uneven grooves 5 provided between the first coating layer 4 and the glass tube wall enters the broken glass tube, immediately stopping the discharge and lowering the temperature of the electrode. The broken glass tube of the discharge lamp 1 is kept surrounded by the protective coating made of the above vinyl chloride coating layers, and external flammable gas does not infiltrate into the glass tube, so the discharge lamp is protected. Even in explosion-proof lighting equipment that does not have a transparent pipe, the flammable gas surrounding the lighting equipment will not catch fire and explode. Moreover, since the glass tube surface of the heating electrode part of the discharge lamp is covered with asbestos 7, which is a nonflammable heat insulating material, the high temperature of the electrode is not transmitted to the vinyl chloride coating covering the surface, and the vinyl chloride coating does not come into contact with the electrode. This allows the protective coating to be maintained at a lower temperature than in conventional discharge lamps of this type. Tables 3 and 4 show the measured temperature rise of each part of the vinyl chloride coating in the 40W and 20W discharge lamps according to the present invention.

【table】

[Effect of idea]

As described above, the discharge lamp according to the present invention is an explosion-proof lighting device equipped with respective lamp nipples at both ends to be attached to a lamp socket, and a transparent protective coating is applied to the glass tube between them. The glass tubes are each covered with an insulating material made of asbestos or ceramic, and the entire length of the discharge lamp, including the insulating material from a part of each lamp nipple, is connected to the glass tube wall by a transparent and at least flame-retardant plastic coating. By storing a predetermined amount of air in between and covering it airtight, the temperature of the protective coating is kept low, and even if the discharge lamp is damaged during lighting, the flammable gas will not ignite and explode, and the discharge will continue. It is possible to obtain a discharge lamp for explosion-proof lighting equipment that can be safely used until the end of the lamp's life.

[Brief explanation of drawings]

FIG. 1 is a partial sectional view showing one end of an embodiment of a discharge lamp according to the present invention, and FIG. 2 is a partial sectional view showing one end of a conventional discharge lamp. 1...Discharge lamp, 3...Lamp nipple,
4, 8, 9...Plastic coating, 7...Asbestos.

Claims (1)

[Scope of utility model registration request] In discharge lamps for explosion-proof lighting equipment, which have lamp nipples at both ends that are attached to lamp sockets, and a glass tube between them with a protective coating of transparent plastic, the glass tube near the electrodes at both ends is made of asbestos or ceramic. respectively covered with a thermally insulating material, the entire length of the discharge lamp including the thermally insulating material from a portion of each lamp nipple being covered with a transparent and at least flame-retardant plastic coating,
A discharge lamp characterized by having a predetermined amount of air stored between a glass tube wall and an airtight covering.