JPH0336985A - Motor-driven blower - Google Patents

Abstract

PURPOSE:To prevent a power device of an inverter from damaging due to an abnormal overheat by detecting the temperature of the device, and lowering or stopping the output of the inverter if the detected voltage is a predetermined temperature or higher. CONSTITUTION:If the temperature of an arranging part of a thermistor 33 becomes high, the electric resistance of the thermistor 33 gradually increases, and an input voltage (c) to a comparator 31 also rises. If the input voltage C exceeds V0, the input voltage (c) to the comparator 31 is inverted from negative to positive. The comparator 31 is turned OFF by the inversion, and the output (d) of the comparator 31 is opened. When the output (d) of the comparator 31 is opened, the input voltage (e) of a comparator 32 is inverted from negative to positive by VH. The comparator 32 is turned ON by the inversion, and the output voltage (f) of the comparator 32 becomes VL. Thus, a control voltage (z) also becomes VL, and a motor 11 is stopped.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an electric blower that can be used in vacuum cleaners, etc., and particularly relates to an electric blower that can be used in vacuum cleaners, etc., and in particular, an electric blower that is integrated with a brushless electric motor, a fan, and an inverter control device. This is related to an electric blower.

[Conventional technology] Conventionally, electric blowers used in vacuum cleaners, etc.
For example, an electric motor having a brush structure described in Japanese Patent Publication No. 62-38939 is used. However, the electric motor having this structure is not suitable for performing various types of control such as adjusting the rotation speed.

Therefore, in recent years, electric motors with a brushless structure that can be easily controlled in various ways have been used for electric blowers. A vacuum cleaner using this brushless structure electric motor was published in Japanese Patent Publication No. 63-9.
It is described in Publications No. 5882 to No. 95884.

FIG. 12 is a schematic configuration diagram showing a device equipped with a conventional electric blower described in Japanese Unexamined Patent Publication No. 63-95882.

In the figure, (1) is a device incorporating a blower, which will be described later, and the figure shows a vacuum cleaner.

(2) is the air inlet for blowing, (3) is the inlet (2)
The suction port (
The filter (4) installed internally facing the filter (4) is a discharge port communicating with the suction port (2), and the blower (5) is located in the middle between the filter (3) and the discharge port (4). , (6) are blades of the blower (5), and (7) is an electric motor that rotationally drives the blades (6). The blower (5) is composed of blades (6) and an electric motor (7), and forms an air intake and exhaust path. (8) is an inverter control device that controls the drive of the electric motor (7), and (9) is a power cord for power supply connected to the inverter control device (8).

A conventional electric blower is configured as described above, and power is input through the power cord (9), the electric motor (7) is driven by the inverter control device (8), and the blades (6) are rotated. Accordingly, the blower (5) is operated. By operating the blower (5), air is sucked and discharged from the suction port (2) through the filter (3) to the discharge port (4), thereby functioning as a vacuum cleaner.

[Problem to be solved by the invention] However, the conventional brushless electric motor (
Although the electric blower using 7) can easily control the blower (5), no special measures have been taken in case the electric blower falls into an abnormal situation due to overheating, undervoltage, overcurrent, etc. . For this reason, there is a possibility that various adverse effects as described below may occur.

Normally, a large amount of current flows through the inverter control device (8) that drives the electric motor (7) of the blower (5), resulting in heat generation. Therefore, when this blower (5) is used as a vacuum cleaner, if the nozzle or filter (3) is clogged with dust, the load will increase and a larger current will flow, resulting in abnormal overheating due to a large amount of heat generated. There was a possibility that If this overheating is significant, the inverter control device (
8) could be destroyed.

Further, this type of electric blower has various control circuits to appropriately control the inverter control device (8) that drives the brushless electric motor (7). Each of these control circuits operates at a predetermined constant voltage, but if the control voltage decreases as the power supply voltage itself decreases, the normal operation of each control circuit may be inhibited.

Furthermore, in this type of electric blower, an especially excessive current flows through the inverter control device (8) when the blower (5) is started, so there is a very strong possibility that the power devices etc. will be damaged. Also, even during normal operation other than when starting up,
When the blower (5) becomes locked or overloaded, or when a large overload current flows due to an abnormality such as a radiation shield, there is a risk of damage to the power devices, etc. of the inverter control bag H (8). was there.

When this type of electric blower is used for a vacuum cleaner, etc., the suction port (2) etc. may become blocked during cleaning, or the air intake volume from the suction port (2) may be extremely restricted. Then, due to the need to increase the suction force, the rotational speed of the electric motor (7) increases abnormally, and there is a risk that the blades (6), the rotor of the electric motor (7), etc. may be damaged by the centrifugal force. Moreover, when the rotational speed of the electric motor (7) increases abnormally, the suction port (2) of the vacuum cleaner cannot be moved smoothly. In addition, with this type of vacuum cleaner, even when the suction port (2) is far from the object to be cleaned, that is, when it is not sucking in any dust, etc.
It was actively sucking. As described above, in this type of electric blower, the conditions in which the electric blower is used are not always constant, and furthermore, the operation of the blower is not adjusted according to these conditions of use. Therefore, depending on the usage conditions, the operating conditions of the blower may be inappropriate.

Note that a temperature fuse has conventionally been inserted into the three-phase busbar of the electric motor (7) as a safety measure for the blower. but,
In order to stop operation due to an abnormal temperature rise, it was necessary to insert temperature fuses into two of the three phases, which was uneconomical.

As described above, conventional electric blowers have poor reliability in terms of safety and reliability, and are not necessarily controlled appropriately according to actual usage conditions.

Therefore, it is an object of the present invention to provide an electric blower that can perform appropriate and reliable control even when the blower is in an abnormal state, and that can perform appropriate control according to the actual usage state of the blower.

[Means for Solving the Problems] The electric blower according to the invention of claim 1 includes a brushless electric motor (11) whose drive is controlled by an inverter (13), and an air blower rotationally driven by the electric motor (11). the power device (81) of the inverter (13) disposed on the blade cover (82) of the fan (12); (81) a temperature detector (26) that detects the temperature of the section; and when the temperature detected by the temperature detector (26) is equal to or higher than a predetermined temperature, the output of the inverter (13) is reduced or It is equipped with an overheat protection circuit (30) ε for stopping the operation.

The electric blower according to the invention of claim 2 includes an inverter (13), an electric motor (11), and a fan (12) similar to those of the invention of claim 1, and controls the inverter (13) and the electric motor (11) as appropriate. A control circuit power supply (25) that applies a predetermined constant voltage to each control circuit, and a Zener diode (44) connected in series to the control circuit power supply (25).
), the potential at the midpoint between the Zener diode (44) of resistor R4J and resistor R41, and the control circuit power supply (25
) are connected in series to resistor R42, resistor R43, and resistor R4.
an undervoltage protection circuit (undervoltage protection circuit) that compares the potential at the midpoint between resistors R42 and R43 of the four resistors, and stops the gate signal to the inverter (13) when the potential on the Zener diode (44) side is low; 40).

The electric blower according to the invention of claim 3 includes the same inverter (13) and electric motor (1) as the inventions of claims 1 and 2 above.
1) and a fan (12), a current detection circuit (17) that detects the current of the DC bus of the inverter (13), and when the current detected by the current detection circuit (17) is less than a predetermined current. It is provided with an overcurrent limiter circuit (50) that stops the gate signal to the inverter (13) and turns on the pulse width modulation signal to the inverter (13) again when the next carrier is input.

The electric blower according to the invention of claim 4 is as follows.
Inverter (13) and electric motor (
11), a fan (2), a current detection circuit (17) similar to the invention of claim 3, and the current detection circuit (17).
) that stops the gate signal to the inverter (13) when the detected current is equal to or higher than a predetermined current; and an overcurrent trip circuit (60 ).

The electric blower according to the invention of claim 5 includes the same inverter (13) and electric motor (1) as the inventions of claims 1 to 4 above.
1), a fan (12), a rotation speed detection means for detecting the rotation speed of the electric motor (11), and a rotation speed detection means for detecting the rotation speed of the electric motor (11) when the rotation speed detected by the rotation speed detection means reaches a predetermined rotation speed. The engine is equipped with a rotation speed limiter circuit (70) that adjusts human power to maintain a predetermined rotation speed.

The electric blower according to the invention of claim 6 includes the same inverter (13) and electric motor (1) as the inventions of claims 1 to 5 above.
1), a fan (12), an air volume detection circuit (24) that detects the air volume blown by the fan (12), and an air volume detection circuit (24) that detects the air volume of the electric motor (11) when the air volume detected by the air volume detection circuit (24) is equal to or higher than a predetermined air volume. ).

The electric blower according to the invention of claim 7 includes the same inverter (13) and electric motor (1) as the inventions of claims 1 to 6 above.
1), a fan (12), and a temperature fuse (15) inserted into the power input line to the inverter (13) and disposed inside the electric motor (11).

[Function] In the electric blower of the invention of claim 1, the blade cover (82) of the blower fan (12) rotationally driven by the electric motor (11) having a brushless structure is provided with the electric blower (11).
A power device (81) of an inverter (13) is provided to control the drive of the inverter (13), the temperature of this power device (81) is detected by a temperature detector (26), and when the detected temperature is equal to or higher than a predetermined temperature, Claim 2, wherein the power device (81) of the inverter (13) is destroyed due to abnormal overheating by reducing or stopping the output of the inverter (13) by the overheating protection circuit (30). The electric blower according to the invention includes a control circuit power supply (11) that applies a predetermined constant voltage to each control circuit that performs various controls of a brushless electric motor (11) and an inverter (13) that drives this electric motor (11). 25), a Zener diode (44) and a resistor R41 are connected in series, and the midpoint potential of the Zener diode (44) and the resistor R41 is connected to the power supply for the control circuit (25), and the resistor R42, the resistor R43, and the resistor R44 are connected to the power supply for the control circuit (25). are connected in series, the potential at the midpoint of resistor R42 and resistor R43 is compared by the undervoltage protection circuit (40), and the Zener diode (44)
By stopping the gate signal to the inverter (13) when the potential on the side is low, the motors (11) and The inverter (13) is controlled so that each control circuit does not malfunction.

In the electric blower according to the third aspect of the invention, a current in a DC bus of an inverter (13) that drives a brushless electric motor (11) is detected by a current detection circuit (17),
When this detected current exceeds a predetermined current, the overcurrent limiter circuit (50) stops the gate signal to the inverter (13), and turns on the pulse width modulation signal to the inverter (13) again with the next carrier input. By doing so, the inverter (13) is activated when the electric motor (11) is started.
The power device (8) is
1) etc., and performs predetermined drive control after startup.

In the electric blower according to the fourth aspect of the invention, a current in a DC bus of an inverter (13) that drives a brushless electric motor (11) is detected by a current detection circuit (17),
When this detected current is less than a predetermined current, the overcurrent trip circuit (60) stops the gate signal to the inverter (13), and even if this detected current decreases again, the stopped state of the gate signal is maintained. In the electric blower of the invention according to claim 5, the electric blower is characterized by suppressing overcurrent from flowing to the inverter (13) during operation of the electric motor (11), and thus features a power device (81), etc.
The rotation speed of the brushless electric motor (11) whose drive is controlled by the rotation speed detection means is detected by the rotation speed detection means, and when the detected rotation speed reaches a predetermined rotation speed, the rotation speed limiter circuit (70) controls the rotation speed of the electric motor (11). By adjusting the input to the electric motor (11) to maintain a predetermined rotation speed,
) always rotates at a rotation speed within a predetermined range.

In the electric blower of the invention of claim 6, an inverter (
13) and a fan (
12) is detected by the airflow detection circuit (24), and when the detected airflow is greater than a predetermined airflow, the output of the electric motor (11) is reduced by the output adjustment means, thereby adjusting the airflow within a predetermined range. In the electric blower of the invention according to claim 7, a temperature fuse (15) is inserted into a power input line to an inverter (13) that drives a brushless electric motor (11), and this temperature fuse (15) is By disposing it inside the electric motor (11), when the electric motor (11) becomes abnormally overheated, the power supply to the inverter (13) and the electric motor (11) is cut off, and the operation of the electric motor (11) is stopped. Stop.

[Embodiment] FIG. 1 is a circuit diagram showing the circuit configuration of an electric blower which is an embodiment of the present invention.

In the figure, (11) is a brushless electric motor such as a permanent magnet synchronous motor, (], ], a) are the stator of this electric motor (11), and (llb) is the rotor. (12) is a fan for blowing air rotationally driven by the electric motor (11), (13) is an inverter that controls the drive of the electric motor (11), (14) is an AC power source, and (15) is a power source for the inverter (13). temperature fuse inserted into the input line,
(16) is an AC/DC converter that converts alternating current to direct current, (
17) is a current detection circuit that detects the DC bus current of the inverter (13). In the electric blower with this configuration, the AC power source (14) is first converted to DC by the AC/DC converter (16), and then converted again to a predetermined AC by the inverter (13). By driving, the fan (12) is rotated to blow air.

(18) is a current setting circuit that sets the current supplied to the inverter (13), and (19) is this current setting circuit (18).
) and the current detection circuit (17
), a current control circuit (20) controls the output 2 so that the detected currents (■) match, a control circuit (20) controls the drive of the inverter (13) as appropriate based on each signal from each control circuit, (21) ) is the rotor (llb) of the electric motor (11)
), (22) is a gate that performs a predetermined negative output by multiple human forces, and (23) is an inverter (13) for driving the inverter (13).
This is a gate amplifier that outputs an appropriate gate signal to each switching element. Note that the Hall IC (21) functions as a rotation speed detection means for detecting the rotation speed of the electric motor (11). (24) is an air volume detection circuit that detects the actual air flow rate due to the rotation of the fan (12), and this air volume detection circuit (24), current control circuit (19), and control circuit (
20) constitutes an output adjustment means that reduces the output of the electric motor (11) when the airflow detected by the airflow detection circuit (24) is less than a predetermined airflow. (25) is a control circuit power supply that applies a predetermined constant voltage to each control circuit that performs various controls of the inverter (13) and electric motor (11); (26) is the temperature of the power devices of the inverter (13); This is a temperature detector consisting of a thermistor, etc. that detects the temperature.

(30) is an overheat protection circuit that adjusts the output of the inverter (13) according to the temperature detected by the temperature detector (26);
40) is a filtering low voltage protection circuit that starts and stops gate signals to the inverters (1, 3) according to changes in the voltage of the control circuit power supply (25), and (50) is a low voltage protection circuit that controls the current detected by the current detection circuit (17). The filtering current limiter circuit starts and stops a gate signal to the inverter (13) according to the current detection circuit (17), and the inverter (13)
The overcurrent trip circuit (70) maintains the stopped state of the gate signal to the motor (
This is a rotation speed limiter circuit that adjusts the input to the electric motor (11) according to the rotation speed of the electric motor (11).

The electric blower of this embodiment is constructed as described above, and the basic drive control of the inverter (13) is performed by the current setting circuit (18). In other words, the current setting circuit (
By appropriately changing the setting value of 18), the output Z of the current control circuit (19) is changed, and the power of the electric motor (11) is continuously changed. This allows the fan (1
Adjust the amount of air blown according to 2) as appropriate.

Further, the electric blower of this embodiment has various protection functions as various safety measures. For example, when the operation of the electric blower becomes dangerous, the gate voltage of the inverter (13) may be cut off, or the current control circuit (19) may be cut off.
) by cutting off the output signal 2 of the motor (
11) has been stopped. Each of these controls is performed by various control circuits, and the electric blower is controlled safely and appropriately according to actual usage conditions. That is, an overheat protection circuit (30), an undervoltage protection circuit (40), an overcurrent limiter circuit (50), and an overcurrent trip circuit (60).
), rotation speed limiter circuit (70), airflow detection circuit (24)
) and a temperature fuse (15) function as a control circuit and means, respectively. These circuits and means will be explained in detail below.

First, the overheat protection circuit (30) will be explained. Second
The figure is a circuit diagram showing the overheating protection circuit of the electric blower shown in Figure 1.
3 and 4 are circuit diagrams showing essential parts of the overheat protection circuit of FIG. 2.

In the figure, (31) and (32) are comparators each functioning as a comparator, and (33) is an inverter (13).
This is a thermistor that detects the temperature of power devices, etc. This thermistor (33) is the temperature detector (26) shown in Figure 1.
), and is arranged on the blade cover as shown in FIG. 11, which will be described later. R31 to R3B are each resistors, and ZD31 and ZD32 are Zener diodes.

Vlf, VOl and vL are predetermined constant voltages supplied from the control circuit power supply (25), and this overheat protection circuit (3
0). However, Vll > V
O>VL There is.

This overheat protection circuit (30) operates as follows. For example, when the temperature of the thermistor (33) installation part is low and the electrical resistance of the thermistor (33) is small, the comparator (
Since the input voltage C to 31) is negative and lower than vO,
The comparator (31) is turned on and the comparator (31)
The output d becomes vI. FIG. 3 is a diagram showing the state at this time. In addition, since the input voltage e of the comparator (32) is connected to the output d of the comparator (31), the input voltage e becomes VL and is lower than vO, so the comparator (32) is turned off, and the comparator (31)
The output f of is in an open state. Therefore, the control voltage 2 becomes the output potential 2 from the current control circuit (19), and the motor (11) is operated.

However, when the temperature gradually rises from the above state and the temperature of the thermistor (33) installation part increases, the thermistor (33)
The electrical resistance of the comparator (33) gradually increases, and the comparator (
The input voltage C to 31) also increases. And input voltage C
becomes VO.

Here, a case where this input voltage C becomes vO will be explained. In order for the input voltage C to become vO, (VL /R32
) + (VZD31/R33) (VZD32/ (R
s + R34) ) Resistance value Rs that satisfies -0
This is when the electrical resistance of the thermistor (33) increases to . However, VZD31 is a Zener diode ZD31
The voltage value of VZD32 is the Zener diode ZD32
, Rs is the electrical resistance value of the thermistor (33), and R31 to R34 are the resistors R31 to R3, respectively.
The electrical resistance values of 4 are shown respectively.

Furthermore, when the temperature rises by -1- and the electrical resistance of the thermistor (33) becomes larger than Rs that satisfies the formula given below,
The input terminal C to the comparator (31) is inverted from negative to positive. This inversion turns off the comparator (31), and the output d of the comparator (31) becomes open. FIG. 4 is a diagram showing the state at this time. Also, -
Once the comparator (31) is turned off, the output d becomes open, and the input voltage C to the comparator (31) further increases due to l, so the so-called chattering phenomenon does not occur and the operation of the comparator (31) is stabilized. . Then, as the output d of the comparator (31) becomes open, the input voltage e of the comparator (32) is inverted from negative to positive by l. This inversion turns on the comparator (32), and the output voltage f of the comparator (32) becomes VL. Along with this, the control voltage 2 also becomes VL, and the operation of the electric motor (11) is stopped.

In addition, when the temperature rises and the electrical resistance of the thermistor (33) increases and it functions effectively as a temperature detector (26), the overheat protection circuit (30) is in the state shown in Figure 4. However, next we will discuss the case where the temperature gradually decreases from this state. That is, in the state shown in Fig. 4, the input voltage C to the comparator (31) is positive, but as the temperature decreases, the electrical resistance of the thermistor (33) also decreases, and the input voltage C to the comparator (31) also decreases. descend. Then, the input voltage C becomes vO.

Here, a case where this input voltage C becomes VO will be explained. In order for the input terminal C to be vO, (Vll / (
R81+R32) ) + (VZD31/R33)
This is when the electrical resistance of the thermistor (33) has decreased to a resistance value Rs that satisfies (VZD32/(Rs +R34))=0. However, VZD31. VZ
D32, Rs, and R31 to R34 all exhibit voltage values or electrical resistance values similar to those explained when the resistance of the thermistor (33) increases.

Furthermore, when the temperature decreases and the electrical resistance of the thermistor (33) becomes smaller than Rs that satisfies the above equation, the input voltage C to the comparator (31) is reversed from positive to negative.

This reversal turns on the comparator (31),
The output d of the comparator (31) becomes l. That is,
The state shown in FIG. 3 is again achieved. Also, in this case, when the comparator (31) is turned on, the output d becomes VL, and the input voltage C to the comparator (31) further decreases, so the so-called chattering phenomenon does not occur and the operation of the comparator (31) continues. Stabilize. Then, in response to the output of this comparator (31), the comparator (32) is also inverted in the same manner as described above, and the control voltage 2 becomes the output potential 2 from the current control circuit (1), and the motor (11) becomes the output potential 2 from the current control circuit (1).
) will be operated.

By providing the overheat protection circuit (3o) as described above as a control circuit for the electric blower, when the temperature detected by the temperature detector (26) consisting of the thermistor (33) is higher than a predetermined temperature, the overheat protection circuit (30) Inverter (13
) can be reduced or stopped.

In particular, the thermistor (33) of this overheating protection circuit (30)
The power device (81) of the inverter (13) similarly arranged on the blade cover is arranged as a temperature detector (26) on the blade cover as shown in FIG.
) can be detected by this thermistor (33). When the temperature detected by the thermistor (33) is higher than a predetermined temperature, the overheat protection circuit (30) causes the inverter (1
By lowering or stopping the output of 3), the power device (81) of the inverter (13) is prevented from being destroyed due to abnormal overheating. As a result, highly reliable control of the electric blower that takes safety into account becomes possible.

Therefore, if an electric blower with this configuration is used for a vacuum cleaner, the nozzle and filter (3) will become clogged with dust and the load will increase, causing an excessive current to flow, resulting in abnormal overheating due to a large amount of heat generated. Even if the inverter (1
3) There is no risk of destruction, and extremely safe operation can be maintained.

Next, the undervoltage protection circuit (40) will be explained. FIG. 5 is a circuit diagram showing an undervoltage protection circuit for the electric blower shown in FIG. 1.

In the figure, (41) is a comparator that functions as a comparator, (42) is a switching transistor, and (43)
(44) is a transistor for preventing chattering, and (44) is a Zener diode which is a constant voltage diode. The output a of this switching transistor (42) is input to the gate (22) in FIG. R41 to R49 are each resistors.

Vll, VQ, and VL are predetermined constant voltages supplied from the control circuit power supply (25) as in FIGS. 2 to 4 above, and l>VO>VL.

In this undervoltage protection circuit (40), the inverter (13)
and a predetermined value for each control circuit that appropriately controls the electric motor (11).
A Zener diode (44) and a resistor R41 are connected in series to a control circuit power supply (25) that applies a constant voltage of , and a resistor R42, a resistor R43, and a resistor R44 are connected in series to the control circuit power supply (25). Connected. and,
The midpoint between the Zener diode (44) and the resistor R41 and the midpoint between the resistor R42 and the resistor R43 are connected to each input terminal of the comparator (41). In a normal state, the input voltage g of the comparator (41) is set lower than that of the input terminal. In this normal state, the voltages and resistance values of the Zener diode (44) and the resistors R42, R43, and R44 are set so that the comparator (41) is turned on. That is, VZD44< VR42 product ((Vll -VL) / (R42+R4L)R
44) )×R42. However, VZD44 is the Zener diode (44) (7) voltage value, VR42 is resistor R42 (7)
) i positive value, and R42 to R44 are each resistor R4
2 to R44 are shown. Note that the normal state here refers to the inverter (13) and electric motor (1
Voltages (VIE, VO) from the control circuit power supply (25) are applied to each control circuit that appropriately controls 1).

VL) maintains a predetermined constant voltage.

This undervoltage protection circuit (40) operates as follows.

For example, in a normal state, the comparator (41) is in an on state, and the output voltage i of the comparator (41) is
is VL. The output voltage i of this comparator (41) is the base voltage of the switching transistor (42), and when i is Vl, the switching transistor (42) is turned on. And gate amplifier (23)
The output voltage a of the switching transistor (42) is supplied to the gate (22) which is manually operated, and the motor (11) is operated.

However, the constant voltage (Vll) from the control circuit power supply (25)
, IVL I) becomes smaller than a predetermined value, the resistance R
42 voltage VR42 becomes small. Then, when the input voltage of the comparator (41) becomes smaller than the input voltage g, the comparator (41) is turned off, and the output i of this comparator (41) becomes an open state. Along with this, the switching transistor (42) is also turned off, the supply of the output voltage a of the switching transistor (42) to the gate (22) is stopped, and the operation of the motor (11) is stopped.

Here, the transistor (43) in this undervoltage protection circuit (40) will be explained. This transistor (4
3) functions as a transistor for preventing chattering. That is, in a so-called normal state in which the input terminal of the comparator (41) is higher than the input voltage g, the output voltage i of the comparator (41) is VL, and the switching transistor (42) is turned on. Along with this, the transistor (43) also turns on, and the resistor R44
becomes a short-circuit condition. As a result, resistor R42 and resistor R4
The current flowing through resistor R42 increases and the voltage V R42 of resistor R42 increases.
becomes larger. Therefore, the input voltage g of the comparator (41) becomes further lower, the operation of the comparator (41) becomes stable, and the switching operation of the switching transistor (42) becomes stable.

By providing the undervoltage protection circuit (40) as described above as a control circuit for the electric blower, the inverter (13
) and the electric motor (11) when the voltage of the control circuit power supply (25) that applies a predetermined constant voltage to each control circuit is unstable, the gate signal to the inverter (13) can be stopped. .

That is, in this undervoltage protection circuit (40), a Zener diode (44) and a resistor R41 are connected in series to the control circuit power supply (25).
) and the potential at the midpoint of resistor R41, and the control circuit power supply (
25), a resistor R42, a resistor R43, and a resistor R44 are connected in series, and the potential at the midpoint of the resistor R42 and resistor R43 is compared by the undervoltage protection circuit (40). By stopping the gate signal to the inverter (13) when the potential is low,
The electric motor (11) and the inverter (13) are controlled only when a stable, predetermined constant voltage is applied to each control circuit from the control circuit power source (25).

Therefore, with this undervoltage protection circuit (40), even if the control voltage decreases due to a decrease in the power supply voltage itself, there is no possibility that the normal operation of each control circuit will be inhibited as in the conventional case. Therefore, the motor (11) and the inverter (13) can be properly controlled at all times, and highly reliable and stable control is possible.

Next, the overcurrent limiter circuit (50) will be explained. FIG. 6 is a circuit diagram showing an overcurrent limiter circuit of the electric blower shown in FIG. 1. In the figure, (11) to (13), and (17) are the same or equivalent components as those in FIG. 1 above.

In the figure, (51) is a comparator that functions as a comparator, and (52) is a Zener diode that is a constant voltage diode. Both R51 and R52 are resistors. V
ll, VOl and VL are predetermined constant voltages supplied from the control circuit power supply (25) as in FIGS. 2 to 5 above, and Vll>VO>VL. VDC is a direct current voltage supplied to the inverter (13). In the current detection circuit (17), (17a) is a current detection resistor, (17b) is an amplifier functioning as an amplifier, and R1 to R4 are each a resistor.

This current detection circuit (17) detects the current of the DC bus of the inverter (13), and has a current detection resistor (17).
7a) is inserted in series with the DC bus. Then, the potential difference between both ends of this current detection resistor (17a) is amplified,
Input to the overcurrent limiter circuit (50). That is, the potential difference (j-k) between the potential j at one end and the potential at the other end of the current detection resistor (17a) is amplified by the amplifier (17b).
The output signal is amplified at 1 to give an output l, which is input to one input terminal of a comparator (51) of an overcurrent limiter circuit (50). Further, a predetermined constant potential m is input to the other input terminal of this comparator (51). And these two inputs (
1 and m), the comparator (51) performs an on or off operation.

This overcurrent limiter circuit (50) operates as follows. For example, in a normal driving state, the inverter (1
The current flowing through 3) is small, and the current detection resistor (17a)
Since the potential difference (j − k) between both ends of is also small, the input of the comparator (51) becomes 1<m, and the input of the comparator (51
) is turned off. Therefore, in this state, the output n of the comparator (51) is in an open state. Therefore, the control voltage 2 becomes the output potential 2 from the current control circuit (19), and the motor (11) is operated.

However, when starting the electric motor (11), etc., the inverter (
13) increases, the current detection resistor (17a
) also increases. Then, when the human power of the comparator (51) increases by 1 to a voltage where 1>m, the comparator (51) turns on. When the comparator (51) is on, the comparator (51)
The output n of 51) becomes VL. Along with this, the control voltage 2 also becomes Vl, and the operation of the electric motor (11) is stopped.

Note that when the next triangular wave carrier that performs pulse width modulation in the control circuit (20) is input, the inverter (
13) is driven again and power is supplied to the electric motor (11). In the end, the DC bus current flows through the Zener diode (52
), and the current flowing through this DC bus is suppressed to a predetermined value or less and continues to flow.

By providing the overcurrent limiter circuit (50) as described above as a control circuit for the electric blower, the inverter (1
3) Current detection circuit (17) that detects the current of the DC bus
When the current detected by the inverter (
The gate signal to the inverter (13) can be stopped and the pulse width modulated signal to the inverter (13) can be turned on again with the next carrier input.

Therefore, with this overcurrent limiter circuit (50),
If excessive current flows through the inverter control device (8) when the blower (5) is started, the gate signal to the inverter (13) is stopped, thereby preventing damage to power devices and the like. Further, after startup, predetermined drive control is performed.

As a result, the electric motor (11) and the inverter (13) can be controlled with high safety and reliability, and adverse effects on other electrical devices used in the same outlet etc. can be reduced.

Furthermore, the overcurrent trip circuit (60) will be explained. FIG. 7 is a circuit diagram showing an overcurrent trip circuit of the electric blower of FIG. 1.

In the figure, both (61) and (62) are comparators that function as comparators. R61 to R63 are each resistors, ZD61 and ZD82 are Zener diodes, and D61 is a diode.

v■, VOl and VL are predetermined constant voltages supplied from the control circuit power supply (25) as in FIGS. 2 to 6 above. Note that 1 is the current detection resistor (17a) sent from the amplifier (17b) of the current detection circuit (17) in FIG.
) is a voltage signal that is amplified by an amplifier (17b).

This overcurrent trip circuit (60) includes a current detection circuit (
Voltage signal l from 17) is divided by resistor R61 and resistor R62, and voltage 0 after this voltage division and Zener diode ZD8
The comparator (61) performs an on or off operation by comparing the voltage p determined by 1 with the voltage p determined by the comparator (61).

This overcurrent trip circuit (60) operates as follows. For example, in a normal driving state, the inverter (1
3) is small, and the output 1 from the current detection circuit (17) is also small. Therefore, the comparator (61)
input 0 and input p become o<p, and the comparator (61
) is turned off. In this state, the output q of the comparator (61) is in an open state. Also, a comparator (62)
Since the human power is the same as that of the comparator (61) and the same operation is performed, the output of the comparator (61) is also in an open state. Therefore, the control voltage 2 becomes the output potential 2 from the current control circuit (19), and the motor (11) is operated.

However, if the current flowing through the inverter (13) increases due to some abnormality, for example, an excessive load is applied to the electric motor (11), both comparators (61),
The input O to (62) becomes high. And the inverter (
When the current flowing through the comparators (61) and (6) further increases and the relationship between the input O and the input p becomes o>p,
2) is activated. That is, both comparators (61),
(62) are both turned on, and the comparator (61)
The output q of the comparator (62) and the output 2 of the comparator (62) are both Vt
Since the control voltage 2 also becomes VL, the operation of the electric motor (11) is stopped.

Also, on -day, the comparator (61) turns on and the output q becomes Vl, the human power p becomes the voltage (VL) created by this VL and the Zener diode ZD61.
+VZD61). Note that the Zener diode ZD6H1VI is selected so that +VZDf31<0, and the input p of the comparator (61) is always negative. Therefore, even if the current of the inverter (13) decreases to some extent, the voltage of input 0 will only become positive or O, so the relationship between input 0 and human power p will continue to be o>p, and the electric motor (11) will operation remains stopped.

In addition, in order to make the relationship between input 0 and human power p to be o<p again, the human power of the control circuit power supply (25) or AC power supply (14) is stopped and Vl+ and IVL are reduced to near VO.
All you have to do is turn on the power again.

By providing the overcurrent trip circuit (60) as described above as a control circuit for the electric blower, the inverter (1
3) Current detection circuit (17) that detects the current of the DC bus
When the current detected by the inverter (
13), and even if the detected current decreases again, the stopped state of the gate signal can be maintained.

Therefore, with this overcurrent trip circuit (60),
Even during normal operation other than when the blower (5) is started,
When the blower (5) is locked or overloaded, or when a large overload current flows due to an abnormality such as a lay-off, the gate signal to the inverter (13) is stopped, so power devices, etc. Damage can be prevented.

In particular, by providing this overcurrent trip circuit (60), it is possible to prevent damage to power devices and the like that cannot be prevented by the overcurrent limiter circuit (50).

That is, the DC bus current of the inverter (13) is suppressed to a predetermined current value or less by the overcurrent limiter circuit (50), but if the output of the inverter (13) is short-circuited, the Overcurrent limiter circuit (
50) An abnormal current flows due to the delay in response. Even in such a case, this overcurrent trip circuit (6
0) is because damage to the power devices of the inverter (13) can be prevented.

As a result, the electric motor (11) and the inverter (13) can be controlled with high safety and reliability.

Next, the rotation speed limiter circuit (70) will be explained. FIG. 8 is a circuit diagram showing a rotation speed limiter circuit of the electric blower shown in FIG. 1.

In the figure, (71) is F/V that converts frequency and voltage.
The converter (72) is a comparator that functions as a comparator. Note that the Hall IC (21) functions as a rotation speed detection means for detecting the rotation speed of the electric motor (11).

This rotation speed limiter circuit (70) uses a Hall IC (2
The rotational frequency of the electric motor (11) detected in step 1) is converted into a voltage signal S by the F/V converter (71), and
2) Manually input power to one of the input terminals. Further, a predetermined reference voltage t is manually applied to the other input terminal of this comparator (72).

Then, this human power S and input t are compared, and when Sat, the comparator (72) is turned on, and the comparator (72) is turned on.
72) output 2 becomes VL, and the control voltage 2 also becomes V
It becomes L. As a result, the power supply to the inverter (13) is stopped, and the operation of the electric motor (11) is stopped. Note that the rotation speed of the electric motor (11) is controlled by the reference voltage t.

By providing the above rotation speed limiter circuit (70) as a control circuit for the electric blower, when the rotation speed detected by the electric blower (11) by the Hall IC (21) reaches a predetermined rotation speed, The input can be adjusted to maintain a predetermined rotation speed.

Therefore, with this rotation speed limiter circuit (70),
Even when this electric blower is used as a vacuum cleaner, etc., the suction port (2) etc. may become blocked during cleaning, or the suction port (2)
Even if the intake air volume from the motor (7) is extremely restricted, the rotational speed of the electric motor (7) is suppressed to a predetermined rotational speed or less. is not damaged by centrifugal force. Moreover, since the rotational speed of the electric motor (7) does not increase abnormally, the suction port (2) of the vacuum cleaner can be smoothly moved.

As a result, regardless of the usage situation of the electric blower, the electric motor (1
. In addition, when this electric blower is used in various devices, the usability of these devices is improved.

Next, a description will be given of means for adjusting the amount of air blown according to the usage situation of the electric blower by means other than the above-mentioned control circuit. That is, the output adjustment means for adjusting the output of the electric motor (11) that rotationally drives the fan (12) for blowing air will be explained. FIG. 9 is a circuit diagram showing a power control circuit based on the air volume of the electric blower shown in FIG. 1, and FIG. 10 shows the relationship between the rotation speed and air volume depending on the difference in current of the electric blower according to an embodiment of the present invention. It is a characteristic diagram. In the figure, (17) to (19), (21), and (24) are the same or corresponding components to the components in each of the above figures.

In the power control circuit shown in this figure, the output from the Hall IC (21), which is the rotation speed detection means for detecting the rotation speed of the electric motor (11), and the output 1 from the amplifier (17b) of the current detection circuit (17) are It is input to the air volume detection circuit (24). The air volume detection circuit (24) outputs an output V according to the air volume from each of these lines, and inputs this output V to the current control circuit (19).

This current control circuit (19) also includes a current setting circuit (1
The current 1 ref from 8) and the current I detected by the current detection circuit (17) are also input at the same time. Current control circuit (19
) control signal 2 is controlled according to each of these inputs. This takes advantage of the fact that the air volume, current I, and rotation speed have a predetermined relationship (see FIG. 10). Therefore, by utilizing this characteristic, the air volume can be determined by detecting the current (2) and the rotation speed.

In other words, the output V of the air volume detection circuit (24) increases as the air volume increases, but by inputting this output signal V to the current control circuit (19), the air volume increases from the relationship with the current value ■. When the current is high, the inverter (
13) The DC bus current (■) stabilizes.

By providing the above output adjustment means as a control circuit of the electric blower, the inverter (13) and the electric motor (11
) detects the amount of air blown by the fan (12) which is rotated by The amount of air blown can be maintained.

Therefore, with this output adjustment means, when this electric blower is used for a vacuum cleaner or the like, the input current to the inverter (13) can be suppressed when the suction port (2) is far from the object to be cleaned. Therefore, efficient and quiet cleaning can be performed.

As a result, the electric blower (11
) can be suppressed to a predetermined number of rotations or less, and the rotation speed of the electric motor (1
1) and the inverter (13) can be properly and stably controlled. In addition, when this electric blower is used in various devices, the usability of these devices is improved, and at the same time, the environment in which they are used can be improved.

Here, the temperature fuse (15) of the electric blower will be explained. FIG. 11 is a sectional view showing a main part of the structure of an electric blower according to an embodiment of the present invention.

In the figure, (9), (11), (12), (15), and (
33) is a component that is the same as or corresponds to the component in each figure in 1.

In the figure, (81) is a power device for the inverter (13), which is composed of a diode, a transistor, and the like. A blade cover (82) is made of, for example, aluminum, and is disposed facing the fan (12). Cooling fins (83) project forward from the fan (12) to form a duct, and are designed to increase the contact area between the intake air flow and the vane cover (82). (84)
is a circuit cover made of metal material such as steel or copper, and covers the inverter (13) and power device (81).
etc., and acts as a shield from electromagnetic noise. (85
) is the intake air passage for this electric blower, and (86
) is an exhaust air passage for exhaust. In addition, in this electric blower, in order to detect the temperature of the power devices of the inverter (13), etc., a thermistor (33) functioning as a temperature detector (26) is disposed on the blade cover (82) as described above. There is.

In this electric blower, the temperature fuse (15) is inserted into the power input line to the inverter (13) as shown in FIG. 1, and is also arranged inside the electric motor (11).

By inserting and arranging the temperature fuse (15) in this way, when the electric motor (11) becomes abnormally overheated, the power supply to the inverter (13) and the electric motor (11) is cut off. , ) can be stopped. Moreover, this can be achieved with one temperature fuse (15).

Therefore, the electric motor (11) can be controlled extremely safely and economically at a lower cost than the conventional method in which temperature fuses are inserted into two of the three-phase busbars of the electric motor (7).

By the way, in each of the above explanations, an overheat protection circuit (30), an undervoltage protection circuit (40), and an overcurrent protection circuit are used as control circuits or means for controlling the electric blower safely and appropriately according to the actual usage conditions. The output adjustment means including the limiter circuit (50), overcurrent trip circuit (60), rotation speed limiter circuit (70), airflow detection circuit (24), and temperature fuse (15) have been individually explained. Of course, these circuits and means may be installed individually in the electric blower, but they may also be installed in appropriate combinations depending on the purpose of use and circumstances, or all of these circuits and means may be installed. You can.

[Effects of the Invention] As explained above, in the electric blower of the invention of claim 1, the power device of the inverter is disposed on the blade cover of the fan for blowing air, and the temperature of the power device portion detected by the temperature detector is The electric blower is extremely safe because the overheat protection circuit reduces or stops the inverter's output when the temperature exceeds a predetermined temperature, thereby preventing the inverter's power devices from being destroyed due to abnormal overheating. A high level of operation can be maintained.

The electric blower according to the second aspect of the invention has a potential at the midpoint between a Zener diode and a resistor connected in series to a control circuit power source that applies a predetermined constant voltage to each control circuit for controlling various types of motors and inverters. , the undervoltage protection circuit compares the potential of the series resistor connected in series with the power supply for the control circuit, and stops the gate signal to the inverter when the potential of the Zener diode side is low. @The motor and inverter are controlled only when a stable, predetermined constant voltage is applied from the control circuit power supply, and each control circuit always properly controls the motor and inverter without malfunctioning, ensuring high reliability. Able to achieve a high and stable [6].

In the electric blower according to the invention of claim 3, when the current of the DC bus of the inverter detected by the current detection circuit is equal to or higher than a predetermined current, the overcurrent limiter circuit stops the gate signal to the inverter, and also stops the gate signal to the inverter. Carrier width modulated signal following.

By turning it on again with input, it protects power devices by suppressing excessive current flowing to the inverter when starting the motor, and performs predetermined drive control after startup, preventing damage to power devices, etc. The electric motor and inverter can be controlled with high safety and reliability, and the adverse effect on other electric devices used in the same outlet etc. can be reduced.

In the electric blower according to the invention of claim 4, when the current of the DC bus of the inverter detected by the current detection circuit is equal to or higher than a predetermined current, the overcurrent trip circuit stops the gate signal to the inverter, and the detected current is By maintaining the stopped state of the gate signal even if it decreases again, it is possible to prevent overcurrent from flowing to the inverter during operation of the motor and protect the power devices, etc.; Enables safe and reliable control of motors and inverters. Furthermore, by providing this overcurrent trip circuit, damage to the power devices of the inverter can be prevented even if an abnormal current flows due to a delay in the response of the overcurrent limiter circuit, such as when the output of the inverter is short-circuited.

In the electric blower according to the invention of claim 5, when the rotational speed of the electric motor detected by the rotational speed detection means reaches a predetermined rotational speed, the input to the electric motor is adjusted by a rotational speed limiter circuit to maintain the predetermined rotational speed. By doing this, the motor always rotates within a predetermined rotation speed, so regardless of how the electric blower is used, the motor rotation speed can be suppressed to a predetermined rotation speed or less, which improves the safety of the motor and inverter. Provides highly stable control.

In the electric blower according to the invention of claim 6, when the amount of air blown by the fan detected by the air amount detection circuit is equal to or greater than a predetermined air amount,
By reducing the output of the electric motor using the output adjustment means, the amount of air blown can be maintained within a predetermined range, so the rotation speed of the electric motor can be suppressed to a predetermined rotation speed or less depending on the usage situation of the electric blower, and the motor and inverter This enables proper and stable control of

In the electric blower according to the seventh aspect of the invention, a temperature fuse is inserted into a power input line to an inverter that drives a brushless motor, and this temperature fuse is disposed inside the motor, thereby preventing the motor from becoming abnormally overheated. When this occurs, the power supply to the inverter and motor can be cut off and the motor operation can be stopped. Moreover, this can be achieved with a single temperature fuse, making it possible to control the motor extremely safely.
Furthermore, it is inexpensive and can be done economically.

[Brief explanation of drawings]

Fig. 1 is a circuit diagram showing the circuit configuration of an electric blower which is an embodiment of the present invention, Fig. 2 is a circuit diagram showing an overheat protection circuit of the electric blower shown in Fig. 1, and Figs. Figure 2 is a circuit diagram showing the main parts of the overheat protection circuit, Figure 5 is a circuit diagram showing the undervoltage protection circuit for the electric blower in Figure 1, and Figure 6 is the overcurrent limiter circuit for the electric blower in Figure 1. Circuit diagram shown, No. 7
The figure is a circuit diagram showing the overcurrent trip circuit of the electric blower shown in Fig. 1, Fig. 8 is a circuit diagram showing the rotation speed limiter circuit of the electric blower shown in Fig. 1, and Fig. 9 is the air volume of the electric blower shown in Fig. 1. FIG. 10 is a characteristic diagram showing the relationship between rotational speed and air volume due to differences in current of an electric blower according to an embodiment of the present invention, and FIG. 11 is a circuit diagram showing a power control circuit according to an embodiment of the present invention. FIG. 12 is a sectional view showing a main part of the structure of an electric blower, and FIG. 12 is a schematic configuration diagram showing a device having a conventional electric blower. In the figure, 11: Electric motor 12: Fan 13: Inverter 15: Temperature fuse 17: Current detection circuit 24: Air volume detection circuit 25: Control circuit power supply 26: Temperature detector 30: Overheat protection circuit 40: Undervoltage protection circuit 44: Zener diode 50: overcurrent limiter circuit 60: overcurrent trip circuit 70: rotation speed limiter circuit 81: power device 82: blade cover. In the drawings, the same reference numerals and the same symbols indicate the same or equivalent parts.

Claims (7)

[Claims] (1) A brushless electric motor whose drive is controlled by an inverter, a fan for blowing air rotationally driven by the electric motor, a power device of the inverter disposed on a blade cover of the fan, and an arrangement section for the power device. The power device includes a temperature detector that detects the temperature of the power device section in the vicinity, and an overheat protection circuit that reduces or stops the output of the inverter when the temperature detected by the temperature detector is equal to or higher than a predetermined temperature. An electric blower characterized by: (2) A brushless electric motor whose drive is controlled by an inverter, an air blowing fan rotationally driven by the electric motor, and a control circuit that applies a predetermined constant voltage to each control circuit that appropriately controls the inverter and the electric motor. A potential at the midpoint between a Zener diode and a resistor connected in series to the power source for the control circuit is compared with a potential of a series resistor connected in series to the power source for the control circuit, and the potential on the Zener diode side is determined. An electric blower comprising: an undervoltage protection circuit that stops a gate signal to the inverter when the voltage is low. (3) a brushless electric motor whose drive is controlled by an inverter; a fan for blowing air rotationally driven by the electric motor; a current detection circuit that detects a direct current of the inverter; and a current detected by the current detection circuit that is set to a predetermined value. an overcurrent limiter circuit that stops a gate signal to the inverter when the current exceeds , and turns on a pulse width modulation signal to the inverter again when the next carrier is input. . (4) a brushless electric motor whose drive is controlled by an inverter; a fan for blowing air rotationally driven by the electric motor; a current detection circuit that detects a direct current of the inverter; and a current detected by the current detection circuit is set to a predetermined value. An electric blower comprising: an overcurrent trip circuit that stops a gate signal to the inverter when the current is greater than or equal to , and maintains the gate signal stopped even if the detected current decreases again. (5) A brushless electric motor whose drive is controlled by an inverter, a fan for blowing air rotationally driven by the electric motor, a rotation speed detection means for detecting the rotation speed of the electric motor, and rotation detected by the rotation speed detection means. An electric blower comprising: a rotation speed limiter circuit that adjusts input to the electric motor to maintain a predetermined rotation speed when the rotation speed reaches a predetermined rotation speed. (6) a brushless electric motor whose drive is controlled by an inverter; an air blowing fan rotatably driven by the electric motor; an air volume detection circuit that detects the air volume blown by the fan; and a predetermined air volume detected by the air volume detection circuit. 1. An electric blower comprising: output adjusting means for reducing the output of the electric motor when the air volume is greater than or equal to . (7) A brushless electric motor whose drive is controlled by an inverter, an air blowing fan rotationally driven by the electric motor, and a thermal fuse inserted into the power input to the inverter and disposed inside the electric motor. An electric blower characterized by comprising: