JPS59153024A - Combustion fan - Google Patents

Abstract

PURPOSE:To contrive high pressurization, miniaturization and magnification of a control range of an air quantity of a combustion fan, by making use of a transistor motor, whose ranges of high speed rotation and speed control are wide, as a motor for driving the fan. CONSTITUTION:A transistor motor 2 which is capable of making a high speed rotation and having a wide range of speed control is used as a driving motor of a fan 1 for combustion of a forced supply or discharge gas or petroleum hot water supply machine and an electric current limiting circuit 10 controlling an abnormal high current is provided on a driving circuit 9 of the transistor motor 2. With this construction, the combustion fan 1, which is miniature and having high prssure and a high air quantity, is obtained, resulting in drastic miniaturization of the hot water supply machine. As a result of obtaining a wide range of speed controll peculiarity, an air quantity control range of the combustion fan 1 can be enlarged, and magnification of a combustion range, that is hot water supply peculiarity can be enlarged.

Description

DETAILED DESCRIPTION OF THE INVENTION FIELD OF INDUSTRIAL APPLICATION The present invention relates to combustion fans for forced-air combustion gas or stone water heaters.

Conventional configurations and their problems Gas or oil forced supply/exhaust water heaters, as seen in the configuration shown in Fig. 3, send combustion air to the gas or oil burner 13 using the fan 7 during forced operation. fuel pipe 1
The combustion heat amount and combustion exhaust gas are mixed with the fuel sent in step 4 and twisted in one direction, and the combustion heat and combustion exhaust gas are heat exchanged with water in the 2 l-di heat exchanger 1o, and then concentrated in the waste waste pipe 4 and released into the outside air. It is configured to emit light. In this case, the motor for driving the combustion fan that sends the combustion air has conventionally been a capacitor motor or a circle-ring type motor powered by single-phase AC, so the frequency of the power supply and the motor are roughly synchronized. It was not possible to increase the number of revolutions above that speed, and even during the change in the number of revolutions, it was not possible to make a wide change due to the constraints of synchronous speed or forced slip rotation.

On the other hand, in gas or oil forced combustion water heaters, due to the recent trend toward shorter and shorter light bills and energy conservation, the combustion section needs to have a higher load and the combustion width needs to be expanded, and the fans used for this are: Inevitably, it is necessary to increase the pressure, reduce the size, and further expand the air volume control range.

However, there is generally a proportional law for fans: pressure cx: n2D2° air volume ocD'-nD (where n: rotation speed, D two-impeller outer diameter), and to increase the pressure of the fan,
It is necessary to increase the rotation speed n or increase the outer diameter of the blades, but increasing the outer diameter of the blades inevitably leads to larger fans, so it is most efficient to use high pressure and small size. To achieve this, the rotational speed n must be increased.

However, when increasing the fan rotation speed, with conventional condenser motors or twisted wire motors, it is impossible to increase the speed beyond the power supply synchronous speed at the maximum due to the reasons mentioned above, and the fan naturally becomes larger and the air volume increases. The scope of control also creates constraints;
This has the drawback of restricting the ability to make water heaters lighter, thinner, shorter, and more energy efficient.

OBJECT OF THE INVENTION The present invention solves such conventional problems, and aims to increase the pressure, reduce the size, and control the air volume of combustion fans as gas or oil forced supply/exhaust water heaters become more highly loaded, save energy, and become smaller. The purpose is to expand the scope.

Structure of the Invention In order to achieve this object, the present invention uses a transistor motor for the drive motor of the fan, which is capable of high speed rotation and extremely smooth speed control characteristics, to drive the fan at a speed higher than the synchronous speed of the power supply. In addition to driving the transistor motor and controlling the speed over a wide range, the transistor motor drive circuit is provided with a current limiting circuit.

This configuration prevents damage to the drive circuit due to the sudden starting current that occurs when starting the transistor motor, controls the fan's rotation speed at high speed and over a wide range, increases the pressure generated by the fan, and is compact and can be used over a wide range. Description of Embodiments Two embodiments of the present invention will be described below with reference to the drawings.

In Figure 1, 1 is the impeller of the Mo-Fugetsu fan, 2 is the 1
This is a transistor motor for driving an impeller, and this transistor motor is driven by a drive circuit 9. 1o is
This is a current limiting circuit provided to protect the drive circuit 9 of the transistor motor from the sudden starting current that flows when starting the transistor motor.

3 is an air passage that supplies the air necessary for combustion to the burner 5, and the exhaust gas and generated heat generated by combustion in the burner 6 flow as shown by the arrow, and pass through a heat exchanger 6 placed in the middle.
It exchanges heat with water and is supplied to the hot water supply port 8. 4 is a gas or oil fuel supply pipe and a closing cock, and 7 is a water supply pipe.

In such a configuration, the impeller 1 of the fan is directly connected to and driven by the transistor motor 2 capable of high-speed rotation, so that the rotation speed reaches a rotation speed higher than the periodic speed of alternating current, which is approximately proportional to the square of the rotation speed. Due to the proportional law of pressure and the proportional law of air volume, which is approximately proportional to the rotational speed, the pressure and air volume characteristics of the fan increase significantly. An example of this is shown in FIG. In Fig. 2, the fan shown as a conventional example is a condenser motor with a power of 280 Or, I), m. In this case, the impeller diameter is 180 mm, and the impeller is operated in two stages in series. In contrast,
Equivalent pressure and air volume characteristics reduce rotation speed to 630 Or, p, In
. This shows that it can be obtained with an impeller diameter of 110 mm and a single stage fan.

7 - Therefore, the diameter of the fan can be reduced by about 40%, and the volume ratio including the drive motor can also be reduced to about 40%.

On the other hand, the transistors in the drive circuit 9 of the transistor motor generally have some concerns about abnormally high currents. Therefore, in order to properly protect against the instantaneous increase in starting current that occurs when starting the transistor motor, the drive circuit 9
By providing the current limiting circuit 10 immediately in front of the □, even if a current exceeding the allowable current is generated, this can be restricted and abnormal damage to the drive circuit 9 can be prevented.

In this example, the case where the combustion fan is placed on the air supply side is exemplified, but even in a system where the combustion fan is placed on the exhaust side and the combustion exhaust gas is forcibly discharged, the exhaust heat from the fan and transistor motor is There is no problem at all as long as the influence of

More than the effects of the invention, the present invention improves the combustion and
By using a transistor motor that can rotate at high speed and has a wide speed control range as the drive motor for the baking fan, and by adding a current limiting circuit to the transistor motor drive circuit to suppress abnormally high current, we have achieved the following: Effects can be obtained.

(1) Utilizes the fan's air volume and pressure characteristics, which are proportional to the rotation speed and its square, to create a small drop and high pressure.

A combustion fan with a high amount of heat can be obtained, and as a result, the above-mentioned water heater can be significantly reduced in size.

(2) As a result of obtaining a wide range of speed control characteristics, the air volume control range of the combustion fan can be expanded, and as a result, the combustion range of the water heater can be expanded, that is, the hot water output characteristics can be expanded.

(→ Minimum to maximum combustion characteristics) Non-optimal fuel and air ratios can be set for each combustion characteristic, making it possible to save energy in the water heater.

(4)) Since transistor motors do not have brushes like commutator motors, there is no need for maintenance and inspection, and in line with the action of the current limiting circuit in the drive circuit of transistor motors, they have extremely long lifespans. It can be measured.

[Brief explanation of the drawing]

FIG. 1 is a configuration diagram of a combustion fan according to an embodiment of the present invention, FIG. 2 is a characteristic diagram thereof, and FIG. 3 is a configuration diagram of a conventional combustion fan. 1°°°”°゛ Impeller, 2...Transistor motor, 5...Burner, 6...Heat exchanger, 9...Drive circuit, 10...Current limiting circuit. Name of agent: Patent attorney Toshio Nakao Haga 1st person 2nd person
Zuo t mj/Biao. Figure 3

Claims (1)

[Claims] A combustion fan body is provided to supply combustion air to the burner,
This combustion fan rotates at a constant rotation speed or higher, is driven by a transistor motor with a rotational speed control ratio of 1:3 or more, and is equipped with a current limiting circuit in the drive circuit of the transistor motor.