JPH03284189A - Axial flow fan - Google Patents

Abstract

PURPOSE:To enable continuous variation of a low rotation speed by controlling the rotation speed through changes in conduction time width of each stator coil. CONSTITUTION:A rotor position detection means 3 detects rotor positions: in response to this, a phase switching circuit 4 drives either of transistors 7, 8, whereby stator coils 5, 6 are electrified alternately to set the rotor in rotation. A temperature detection means 23 detects the temperature of a cooling object and its surroundings, so that a command value generation circuit 24 outputs speed command values corresponding to detected temperatures. A speed control circuit 25 prepares OFF time of a width corresponding to its command value, and the phase switching circuit 4 restricts the conduction time of the stator coils 5, 6 by the OFF time. Therefore, the larger the OFF time is, the shorter the conduction time becomes with the result that the rotation speed becomes low.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to highly functional axial flow fans for cooling equipment using brushless motors.

[Conventional technology]

FIG. 6 is a circuit diagram for driving a motor portion of a conventional axial fan disclosed in, for example, Japanese Patent Application Laid-Open No. 59-37895.

In the figure, (1) is a DC power supply, (2) is a circuit adjustment resistor, (3) is a rotor position detection means consisting of a Hall element, etc., and (4) is a rotor position detection means based on the output of the rotor position detection means (3). Steeta coil f51 (finger switching circuit that switches the current flowing through 61, (71 (81 is a sliding switch) switching circuit (4
) by J) ONloFF transistor, (9)
is an inverting circuit, Ql is an open-phase operation circuit that prohibits the driving of the stator coil of the special phase, ←B is a transistor that is turned on when the open-phase operation circuit flG is activated, and az is a transistor that detects rotor stop during open-phase operation. , starting compensation circuit for starting, f13
) is a transistor that is turned on when the startup compensation circuit operates.

I is sliding switching circuit (4), stator coil f51 (
61 and an inverting circuit (9).

Next, the operation will be explained.

The position of the rotor is detected by rotor position detection means (3).

The output is amplified by the gold phase switching circuit (4) and transferred to the transistor (7) or the transistor (7) via the inverting circuit (9).
8), stator coil (5) or (6) is energized to generate rotational torque, and as the rotor rotates, stator coils +51 and +61 are alternately energized and continue rotating, and 2 normal operation continues. be done. If you want to reduce the rotational speed of the rotor from this state, operate the open-phase operation circuit Ql and turn on the transistor ←D.
) does not work, and only the stator coil +51 is intermittently energized, resulting in a 22 rotation torque decrease and low speed rotation.

During this open-phase operation, if the rotor stops for some reason during the power-off period of the stator coil (5), rotational torque will not be generated and the rotor will not be able to start. The starting compensation circuit σ2 works like this when the rotor stops rotating.

Since the output of the rotor position detection means (3) does not change, it is monitored by the built-in timer, and when the time exceeds the output, the transistor (L (to) iON is turned on, and the transistor (11) is turned on.
By turning 1 off, phase input operation is canceled.

Even if the stator coil (5) is in the power-off period, the stator coil (6) on the opposite side is in the energized period, so the stator coil (6) is energized and one rotation torque is generated, so there must be no particular obstruction. The rotor starts rotating. When the rotation is restarted, the output of the rotor position detection means (3) changes, so the startup compensation circuit a2 is eventually reset, the transistor (131) is turned off, and the operation returns to open phase operation.

[Problem to be solved by the invention]

Conventional axial fans are configured as described above.
Since the low rotational speed is realized as open-phase operation, it is not possible to change the two rotational speeds continuously, so it was abandoned. Problems such as the need for a start-up compensation circuit to restart the motor when the rotor locks up during open-phase operation have been a challenge.

This invention was made to solve the above-mentioned problems, and its object is to provide an axial flow fan that can continuously change the low rotational speed and does not require a starting compensation circuit.

[Means to solve the problem]

The axial fan according to the present invention includes a stator consisting of a multi-pole magnetized magnet rotor, a multi-phase coil, a blade fixed to the rotor to send cooling air to an object to be cooled, and detecting the position of the rotor. a coil drive circuit that switches phases and energizes the stator coil based on the output of the rotor position detection means; a temperature detection means that detects the temperature of the object to be cooled or the surroundings; A speed command value generation circuit that generates a command value for the rotational speed of the motor according to the output of the temperature detection means, and a time limit for energizing the stator coil by the coil drive circuit according to the command value of the speed command value generation circuit. It is equipped with a speed control circuit.

[Effect]

The speed control circuit according to the present invention controls the rotational speed by changing the energization time width of each stator coil instead of open-phase operation, so that continuous speed change is possible. The startup compensation circuit required during open-phase operation is no longer required.

[Embodiments of the invention]

An embodiment of the present invention will be described below with reference to the drawings. The same or equivalent parts as in the prior art are given the same reference numerals to avoid duplication of explanation. FIG. 1 is a circuit diagram of a motor driving circuit of an axial fan according to the present invention. In the figure, (c) is a temperature detection means that detects the temperature of the object to be cooled or the surroundings, and (2) is a command that decisively commands the rotational speed of the motor according to the temperature detected by the temperature detection means (c). The value generation circuit 2s uses a timer to set an off time that changes based on the command value of the command value generation circuit C141, and this off time is used to set a part of the drive time of the sliding switching circuit (4) (i-OFF). ee is an overheating detection circuit that detects that the temperature of the object to be cooled is abnormally high; @ is the output of the overheating detection circuit. The transistor that turns on, @ is the rotation pulse generation circuit that captures the drive of the stator coil (6) and generates all the rotation pulses, (A) and (to) are the resistors that divide the rotation pulse generation circuit's total voltage, and 0I) is the rotation The transistor that outputs all pulses, 0z, is an alarm output terminal that outputs rotation pulses and overheat detection as a wired OR. FIG. 2 is a time chart of the motor drive circuit. In the figure, To is the off time set to limit the energization time of the stator coil +51 (61) by the speed control circuit marked e.

It is a figure which shows an example of the temperature characteristic of a rotation speed and an overheat alarm.

Next, the operation will be explained. Rotor position detection means (3)
detects the rotor position, and in response, the phase switching circuit (
4) drives one of the transistors (71 (81),
As a result, the system cheetah coils (5) +6+ are alternately energized and the rotor rotates. The temperature detection means (c) detects the entire temperature of the object to be cooled or the surroundings, and outputs the command value generation circuit (goods).
outputs the full speed command value according to the detected temperature.

Speed control circuit Q! i) creates all the off-times with a time width according to the command value, and the phase switching/switching circuit (4) limits the energization time of the stator coils +5+ +6+ by the off-times. In this way, the longer the off time, the shorter the energization time and the lower the rotation speed.

FIG. 2 shows the waveforms of various parts at this time. Here, the off time TO is placed at the beginning of each phase drive time, but it does not have to be at the beginning.

In addition, since this off time is created using a timer, it ends regardless of the nine rotation angles, so there is no need to guarantee startup.

Figure 3 shows an example of this temperature characteristic.
The rotation speed is lowered by increasing the length, and as the temperature increases, the rotation speed is increased, and when the temperature exceeds a certain level, the off time TOi is set to zero, and the rotation speed is rotated at full speed. Also, the off time TO is fixed below a certain temperature.

The number of rotations may be constant. The rotation pulse generation circuit (to) receives the voltage at the connection point between the stator filter (6) and the transistor (8), outputs a number of rotation pulses proportional to the number of rotations, and drives the transistor OD to open the collector. outputs the rotation pulse to the alarm output terminal.

In the rotation pulse generation circuit @, when the stator coil (6) is not energized, the collector voltage of the transistor (8) is high (hereinafter simply referred to as H), and this voltage is divided by the resistor - (to). When the transistor C311'1i is turned on and the stator coil (6) is energized, the collector voltage of the transistor (8) is approximately 0 and is low (hereinafter simply referred to as L), and the transistor all is turned off. In addition.

Here, the collector voltage of the transistor (8) is taken in as an input to the rotation pulse generating circuit (to).

The input or output signal of the phase switching circuit (4) may also be used.

The overheating detection circuit (a) detects (9) by the temperature detection means (c). When the temperature is low, the transistor @ is turned off, so a rotation pulse is output to the alarm output terminal C32. When the detected temperature exceeds a predetermined value, the transistor @iO
Since it is set to N, the alarm output terminal 0z should remain at L.
The abnormality is communicated to the outside.

The following three cases can be considered as cases in which an overheating alarm is issued.

a. The fan is rotating at full speed, but the temperature of the object to be cooled and its surroundings will rise significantly because the filter is clogged or the straddle fan is malfunctioning and cannot reach full speed. I heard it.

b. The fan is rotating at full speed and producing the desired air volume, but
The power transistor overheats due to a failure in the electronic circuit containing the object to be cooled, such as a power transistor.

The ambient temperature of the entire C0 device is too high.

In this way, the alarm output terminal 02 outputs alternating pulses of H and L using rotation pulses so that the rotation speed can be monitored during normal times, but when this output is fixed at H, the rotor is locked. (10) means a lock alarm indicating that the output signal is fixed at L, and a lock alarm or an overheat alarm indicating that the overheat detection circuit (c) has detected an abnormality. It means.

That is, the alarm output terminal C33 makes it possible to identify a lock alarm, an overheat alarm, and a rotation pulse while combining the collector of the transistor @OD into one line as a wired OR.

Next, a motor drive circuit according to another embodiment of the present invention is shown in FIG. This is compared to the configuration shown in Figure 1, in which the two-rotation pulse generating circuit (A) and transistor 0D are used instead.

It is equipped with an abnormally low speed detection circuit (to) and a transistor (b).

The abnormal low speed detection circuit (to) detects whether the motor rotation has not reached the required rotation speed, and the detection level is determined according to the temperature detected by the temperature detection means (Figure 5). The figure shows an example of its temperature characteristics.

Transistor 0 is turned on when the abnormally low speed detection circuit (c) detects abnormally low speed, and outputs an abnormally low speed alarm (11).

In this example, the alarm output terminal is transistor 07) (
) collectors as wired or.

The overheat alarm and abnormally low speed alarm are output together, making it easy to issue external alarms.

Note that the abnormally low speed detection circuit (to) starts from zero speed when the motor is started, so in order to prevent all abnormally low speed alarms from being generated, a function (to) that prohibits abnormally low speed detection for a limited period of time is provided (
(not shown).

〔Effect of the invention〕

As described above, according to the present invention, there is provided a stator consisting of a multi-pole magnetized magnet rotor, a multi-phase coil, a blade fixed to the rotor to send cooling air to an object to be cooled, and a position of the rotor. A rotor position detection means for detecting the temperature, a coil drive circuit for switching the phase and energizing the stator coil based on the output of the rotor position detection means, a temperature detection means for detecting the temperature of the object to be cooled or the surroundings, and Command of motor rotational speed according to the output of the detection means '1IIk
A speed command clear generation circuit that generates the speed command value [1
2) Equipped with a speed control circuit that limits the energization time of the stator coil by the coil drive circuit according to the command value of the generator circuit, so the low rotation speed can be changed continuously, eliminating the need for a starting compensation circuit. This has the effect of providing an axial flow fan that does not require

[Brief explanation of the drawing]

Fig. 1 is a motor drive circuit diagram of an axial fan according to a disaster example of the present invention, Fig. 2 is a time chart of the same motor drive circuit, and Fig. 3 is the rotational speed of the above motor and the temperature characteristics of the overheat alarm. Fig. 4 is a motor drive circuit diagram showing another embodiment of the present invention, Fig. 5 is an abnormality detection temperature characteristic diagram of another embodiment of the same as above, and Fig. 6 is a motor drive circuit of a conventional shaft fan. It is a diagram. In the figure, (11 is a DC power supply, (2) is a resistor, (3)
is the rotor position detection means, (4) is the sliding switching circuit, (
5) +61 is stator coil, +71 (81 is transistor, (9) is inverting circuit, QIj is open phase operation circuit,
(111 is a transistor, a'a is a startup compensation circuit,
Oj is a transistor, (141 is a coil drive circuit, (
(To) is the temperature detection means, 124 is the command value generation surface (13), (To) is the speed control circuit, (A) is the overheating detection circuit, Q
n is a transistor, (2111 is a rotation pulse generation circuit, C32 is an alarm output terminal, and 0 is a low speed detection circuit. In Figure 2, the same reference numerals indicate the same or equivalent parts.

Claims (3)

[Claims] (1) A stator consisting of a multi-pole magnetized magnet rotor, a multi-phase coil, a blade fixed to the rotor and sending cooling air to the object to be cooled, and a rotor position detection means for detecting the position of the rotor. , a coil drive circuit that switches the phase and energizes the stator coil based on the output of the rotor position detection means; a temperature detection means that detects the temperature of the object to be cooled or the surroundings; a speed command value generation circuit that generates a command value for the rotational speed of the motor;
An axial flow fan comprising: a speed control circuit that limits the energization time of the stator coil by the coil drive circuit according to the command value of the speed command value generation circuit. (2) A rotation pulse generation circuit that generates a number of rotation pulses proportional to the rotation speed of the rotor, an overheat detection circuit that generates an output when the detected temperature exceeds a predetermined value, and the output of this overheat detection circuit and the rotation pulses mentioned above. The axial flow fan according to claim 1, further comprising an output line for making the output of the generating circuit a wired OR. (3) Instead of the rotational pulse generation circuit, an abnormally low speed detection circuit that generates an output as abnormally low speed when the rotational speed of the rotor falls below a predetermined value is used, and the output of this abnormally low speed detection circuit and the output of the overheating detection circuit are wired-ORed. The axial fan according to claim 2, further comprising an output line.