JP3141628U - High efficiency heat dissipation technology - Google Patents

Abstract

[PROBLEMS] To reduce the temperature derating of power control elements by developing a technology that efficiently cools electronic equipment with relatively large heat generation, such as built-in power supplies and acoustic amplifiers, with a simple configuration. And miniaturization of heatsinks, and high-power, high-reliability compact power equipment at low cost.
A casing 1 for storing an electronic circuit has a sealed structure excluding an exhaust port and an intake port, a shielding plate 8 that keeps airflows 2 and 5 inside the casing in an ideal state, and By adopting forced air cooling by two cooling fan motors 9, a cooling efficiency of 15% or more is realized as compared with forced air cooling by the prior art.
[Selection] Figure 1

Description

The present invention relates to a heat dissipation technique, and more particularly to a high-efficiency heat dissipation technique in a power supply device and an acoustic amplifier with built-in equipment.

In the case of an acoustic amplifier (power amplifier) used for equipment sound in a movie theater or a multipurpose hall, a model having an output of 1000 W or more is generally used.

The equipment acoustic equipment is usually stored in an EIA standard rack, and in the case of an acoustic amplifier having an output of 1000 W or more, it is common to use a 2U size casing.

A large-sized acoustic adjustment console for studios has a power supply case separate from the adjustment console itself. Since this power supply housing requires a power supply capability of several hundred watts, it is sensitive to sound quality, and therefore a combination of a transformer and a series regulator is usually used. However, a large amount of heat is generated during actual operation, and sufficient heat radiation measures are required to protect the temperature fuse and power control element of the transformer. In many cases, it is common to use a 4U size (about 170 mm) housing.

A technology (see Patent Document 1) of Nippon Marantz Co., Ltd. is disclosed as a similar high-efficiency heat dissipation technology in an acoustic amplifier.

As a similar high-efficiency heat dissipation technique in an acoustic amplifier, there is a technique called Turbo-VCooling (see Non-Patent Document 1) by Peavey Electronics, USA.
JP2003-8270 Explanation of Heat Sink Technology in the homepage of Peave Electronics, Inc. (http://www.peavey.com/support/technotes/poweramps/heatsink.cfm)

Since the acoustic amplifier for equipment acoustics and the power cabinet for the acoustic adjustment console are forced to operate harshly while the installation space is limited, high operating efficiency is required for the power control technology.

A class D method and a class G (class H) method are known as high-efficiency power control techniques.

The class G (class H) method is a power that is divided by the power control element by switching the applied voltage of the class B (including class AB operation) amplifier from two stages to three stages according to the signal input voltage and signal output voltage. It is a special amplifier that reduces loss.

The class D system is a power control system called a digital amplifier, a switching amplifier, etc., and is widely used as a home acoustic amplifier and some commercial acoustic amplifiers.

Since the class D method is more efficient than the mainstream class B method (including class AB operation), in many cases the actual efficiency is overexpressed. However, the increase in efficiency when the efficiency is compared in a severe working state is less than 30%.

In the class D system, when a circuit design corresponding to generation of radiation in a speaker line or a severe working state is performed, sound quality is deteriorated as compared with a class B (including class AB operation) amplifier.

For this reason, the class G (class H) method has become the mainstream as an acoustic amplifier in facility sound.

The class G (class H) method has an efficiency increase of less than 20% compared to the class B method (including class AB operation) in severe operating conditions.

The class G (class H) method dynamically switches the secondary side DC power supply line, so that the outflow harmonics to the primary side power supply line increase and satisfy various power supply harmonic standards compared to the class B method. It becomes difficult.

Outflow harmonics to the primary power line rarely become a major problem as long as the dedicated power line for equipment is used, but the same acoustic amplifier circuit is prototyped using the class B method and class G (class H) method to produce sound quality. When the comparison is made, the class B method is clearly of high quality.

In order to realize an acoustic amplifier having the same housing and working performance as a class G (class H) type acoustic amplifier using the class B method, it is necessary to develop a high efficiency heat radiation technology.

Since the class A system is used in the power supply cabinet for the large acoustic adjustment console, when the downsizing of the casing is indicated, the class D system (switching power supply) is used or the development of a high efficiency heat radiation technology is required.

In particular, since many of the power supply casings used in old-style acoustic control consoles called vintage are difficult to repair, only the power supply casings are custom-made.

Vintage products have a non-constant current or single configuration, so that the performance of the power supply is easily reflected in sound quality and is difficult to realize even when there is a demand for downsizing the power supply housing.

The present invention realizes a 2U enclosure with devices using these conventional methods, and contributes to downsizing and cost reduction of the devices.

FIG. 1 is a schematic top view of an acoustic amplifier that has been confirmed for actual operation, with the top plate removed in order to facilitate confirmation of component placement inside the housing.

Bending-shaped box-shaped housing (reference numeral 1), electronic circuit board (reference numeral 3), power transformer (reference numeral 4), radiator (reference numeral 7), airflow shielding plate (reference numeral 8), cooling fan motor (reference numeral 9) The high-efficiency heat dissipation performance is realized by adopting the arrangement shown in the figure and by adopting a sealed structure except for the exhaust port and the intake port when the top plate is fixed.

A commercially available class G (class H) type acoustic amplifier using a 2U chassis and a class B type prototype acoustic amplifier employing the present invention are measured and compared under the same conditions (room temperature 28 degrees, mono output 1500 W / 4Ω load). The same actual performance was confirmed.

At the time of the actual comparison, the cooling fan motor drive sounds are at the same level in terms of hearing.

From these results and the difference in efficiency of each method, it was concluded that the amount of improvement in heat dissipation efficiency by using the present invention was 15% or more.

It is most suitable for power control technology that requires severe operation with limited installation space, especially for power amplifiers for equipment acoustic amplifiers and large acoustic control consoles.

In FIG. 1, a commercially available general-purpose product is formed except for a box-shaped casing (reference numeral 1) and an electronic circuit board (reference numeral 3) for bending and shaping. The longitudinal section of the radiator (symbol 7) has a shape and dimensions as shown in FIG. 3 and a length of about 40 cm. The airflow shielding plate (symbol 8) is formed by bending a heat-resistant resin plate into the shape shown in the figure and fixing it so that it is in close contact with the fins of the radiator (symbol 7). It is designed as a little less than 2U, and is fixed by crimping by attaching a heat conducting rubber that also serves as a seal in the range of the back panel side 1/2 inside the top of the housing (see Fig. 2). Uses 3M flame retardant thermally conductive acrylic adhesive sheet 9894FR.

The airflow shielding plate (symbol 8) is brought into close contact with the fins of the radiator (symbol 7) by this sealing so that the airflow 1 (symbol 2), the airflow 2 (symbol 5) and the radiator (symbol 7), which are cooling airflows, are used. The contact is regulated to the maximum.

These air flows pass through the fins of the radiator (symbol 7) on the back of the power control element and exhaust from the two cooling fan motors (symbol 9) attached to the exhaust port. By using the case as an auxiliary radiator, the heat dissipation effect is enhanced.

The prototype acoustic amplifier used a highly efficient and low noise Panaflow FBL08A24U manufactured by Panasonic for the cooling fan motor (symbol 9), and confirmed a continuous output of 1500 W (750 W / 2Ω stereo sine wave output) at 28 ° C. for 5 minutes. In addition, 500 W for 8 hours continuous output (250 W / 8Ω stereo sine wave output) was confirmed for practical continuous output in which various protection circuits do not operate.

The acoustic amplifier circuit uses a circuit configuration having the highest power supply utilization efficiency called a vertically symmetric circuit, and a total of eight transistors 2SD2561, 2SB1648 made by Sanken are used as the power control element in the final stage.

FIG. 3 is a cooling fan motor (symbol 9) drive circuit. The control statuses of fan control 1 and fan control 2 are generated from a general detection circuit using a ladder network and a thermistor. Fan control 1 is for attenuator control that controls the cooling fan motor (symbol 9) from low speed to high speed, and the FET is offset so that the minimum starting voltage is applied to the cooling fan motor (symbol 9) when the status is OFF. The fan control 2 is a main switch for turning on / off the cooling fan motor (symbol 9). The two driving FETs are fixed to a radiator (symbol 7) to realize pseudo-stabilized driving using the temperature characteristics of the FETs.

In order to achieve high-efficiency heat dissipation through efficient forced air cooling and the use of an auxiliary radiator in the housing, the housing when using the present invention generates more heat than when using normal forced air cooling.

This amount of heat generation can be adjusted by allowing the temperature protection circuit to operate at the required housing temperature, allowing for a reduction in heat dissipation efficiency.

The cooling fan motor drive sound is at the same level as a standard acoustic amplifier (product of US QSC Audio Products) widely used in various countries in terms of hearing.

If these can be tolerated, it can be applied as a high-efficiency heat dissipation technique for dimming equipment and large-sized computers.

FIG. 2 is a schematic top view inside a housing when the present invention is used in an acoustic amplifier. It is the heat conductive rubber processing schematic diagram to the housing | casing top plate at the time of using this invention for an acoustic amplifier. It is a longitudinal direction sectional view of a radiator (code 7) at the time of using the present invention for an acoustic amplifier. It is a basic diagram of a cooling fan motor (symbol 9) drive circuit.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Case outline 2 Air flow 1 outline 3 Electronic circuit board outline 4 Power transformer outline 5 Air flow 2 outline 6 Power control element outline (Because of a push-pull circuit, two elements are shown as one)
7 Outline of radiator 8 Outline of air flow shielding plate 9 Outline of cooling fan motor

Claims (8)

2. An acoustic amplifier having high efficiency heat dissipation characteristics realized by the component arrangement of FIG. 2 is a power supply device including a switching power supply having a high efficiency heat dissipation characteristic realized by the component arrangement of FIG. 1. 1 is an acoustic amplifier in which two cooling fan motors (symbol 9) are always started, accelerated, and stopped simultaneously. In the component arrangement of FIG. 1, the two cooling fan motors (symbol 9) include a switching power source that always starts, accelerates and stops simultaneously. 1. An acoustic amplifier that employs a shielding plate (reference numeral 8) that keeps the airflow inside the housing in an ideal state in the component arrangement of FIG. 1. A power supply apparatus including a switching power supply that employs a shielding plate (reference numeral 8) that keeps the airflow inside the housing in an ideal state in the component arrangement of FIG. An acoustic amplifier that realizes high-efficiency heat dissipation performance by adopting a sealed structure except the exhaust port and the intake port in the component arrangement of FIG. 1. A power supply apparatus including a switching power supply that realizes high efficiency heat radiation performance by adopting a sealed structure except the exhaust port and the intake port in the component arrangement of FIG.

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