JPS622930Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a DC motor cooling protection device that forcibly blows cooling air to a DC motor and stops the DC motor when the cooling air stops blowing.

Generally, when operating an externally cooled DC motor, it is necessary to immediately stop the operation of the DC motor itself when the cooling air stops blowing.

However, when an anemometer is conventionally used to detect the stoppage of the cooling air, the detection is unstable because the wind pressure of the cooling air is relatively low, and there is a risk of malfunction due to motor vibration. As a result, there was a problem of low reliability and an inability to accurately display abnormalities in the cooling air.

The present invention has been proposed in view of the above-mentioned points, and is capable of reliably detecting the stopping state of the cooling air and stopping the operation of the DC motor, thereby obtaining highly reliable protection performance for the DC motor. The first object of the present invention is to provide a DC motor protection device that is capable of providing a direct current motor protection device, and the second object is to provide a DC motor protection device that can reliably display when the cooling air has stopped due to an abnormal condition. It is something.

The present invention will be explained in detail below with reference to embodiment figures. 1 in the diagram
is an externally cooled DC motor, which is operated when the main relay _R4 in the control panel 7 is energized. The cooling air used to cool the motor 1 is exhausted outdoors through an exhaust duct 9. 2
is a fan motor composed of an induction motor, and has a pulley 11 fixed to its drive shaft 10, and a pulley 12 fixed to the rotating shaft 4 of the blower fan 3. A fan drive belt 13 is stretched. When the fan motor 2 is driven to rotate in this way, the rotational force of the drive shaft 10 is transmitted to the rotating shaft 4 of the blower fan 3 via the pulley 11, fan drive belt 13, and pulley 12, and this blower fan 3 is operated. As a result, cooling air is sent to the DC motor 1 via the air supply duct 8. Further, a rotation detection device 5 is attached to the rotation shaft 4 of the blower fan 3, and is designed to monitor the steady rotation state of the rotation shaft 4. In this embodiment, the rotation detection device 5 is a disc with a slit. 14, a photoelectric relay 15, and a control unit 16.The photoelectric relay 15 detects the rotational state of the rotating shaft 4, and the control unit 16 receives the rotation detection signal output from the photoelectric relay 15, and then controls the blower fan 3. When the control unit 16 detects that the rotation has stopped, the control unit 16 generates a cold air stop signal and closes the contact Cu in the protection circuit section 17.

The protection circuit section 17 starts, stops, and displays the DC motor 1 and the fan motor 2, stops the DC motor 1 when an abnormality occurs, displays an abnormality, etc., and each terminal of the protection circuit section 17 A ₁ , A ₂ ,
B ₁ , B ₂ , C ₁ , and C ₂ are the terminals A _{1 and} C 2 of the control panel 7, respectively.
Connected to A ₂ , B ₁ , B ₂ , C ₁ , and C ₂ . However, in the circuit section for controlling the fan motor 2 of the protection circuit section 17 of the lever, when the push button PB ₁ for starting the fan motor 2 is turned on, the relay Mg for operating the fan motor 2 is activated by the thermo switch.
This causes the normal contact Mg ₁ connected in parallel to the push button PB ₁ to close, self-maintaining the energized state of the relay Mg, and lighting the fan motor operation indicator PL ₁ .
In addition, a regular contact Mg ₂ is connected in parallel to the contact Cu.
is opened, and the control unit 16 detects that the rotation of the blower fan 3, which has started rotating by being connected to the power supply through another normally open contact (not shown) operated by the excitation of the relay Mg, has stopped. contact
Interlock relay Xo is kept de-energized until Cu is closed, and DC motor 1 in control panel 7
The operating circuit is no longer locked from operating. On the other hand, in the circuit section for controlling DC motor 1, relay R ₂ is always energized via normally closed push button PB ₂ for stopping DC motor 1, and interlock relay Xo is de-energized as described above. Therefore, normally open contact r ₂₁ and normally closed contact X _O2
Terminals A ₁ and A ₂ are connected in series, and conduction is established between them. When pushbutton PB ₃ for starting DC motor 1 is turned on, the DC motor operation relay is activated.
_R1 is energized, and the normally open contact _R12 connected in parallel to the pushbutton _PB3 is closed, so that this DC motor operation relay _R1 is self-maintained in the energized state, and the DC motor start indicator light _PL2 is lit.
The normally open contact r ₁₃ between the terminals B ₁ , B ₂ and the normally open contact r ₁₁ of the relay X ₁ , X ₂ circuit are closed. Thus the control panel 7
When the normally open contact _r13 is closed between the terminals _B1 and _B2 , the main relay _R4 is energized and the DC motor 1 is started, and the terminals _B1 and _B2 are connected on the control panel 7 side.
By closing the contact R ₄ connected to the main relay R ₄ , the main relay R 4 is self-maintained in the energized state, and is also connected to the terminals C ₁ and C ₂ on the protection circuit section 17 side and the terminal C ₁ on the control panel 7 side. , C ₂ are energized _{, and the DC motor operation indicator light PL 3 is} turned on. In addition, in the abnormality display circuit section, the normally open contact _R11 is connected in series with _the normally open contact _XO1 and _the fan abnormality display _relay When the interlock relay _Xo is activated and normally _open contact Fan error display relay x ₁
is energized to indicate that an abnormality has occurred in the drive of the blower fan 3 in the circuit not shown in the diagram, and since the normally closed contact X _O2 between terminals A ₁ and A ₂ is opened, there is no connection between terminals C ₁ and C ₂ . When the voltage state is reached and the relay R ₃ is de-energized and the normally closed contact R ₃₂ is closed, the DC motor abnormality display relay X ₂ is energized to indicate that the drive of the DC motor 1 has stopped in a circuit not shown. relay
At the time when R ₃ is de-energized, main relay R ₄ connected in parallel with relay R ₃ is also de-energized and DC motor 1 is stopped. After this, when normally closed pushbutton PB ₂ is turned off, relay R ₁ for DC motor operation is activated.
self-holding is released and becomes de-energized, fan error display relay X ₁ and DC motor error display relay
Both X ₂ are in a de-energized state. Also, the DC motor start indicator light PL ₂ goes out. After this, when the normally closed pushbutton PB ₄ is turned off, the self-holding of the relay Mg is also released and the operation of the fan motor 2 is also stopped. At this time, all the indicators PL ₁ , PL ₂ , and PL ₃ are also turned off. On the other hand, when the fan motor 2 is overloaded in the normal operating state of the DC motor 1 as described above, an excessive current flows through the thermal relay Th, and this excessive current may cause the thermal relay Th to open, or the fan motor 2 may become overloaded. 2
When the rotation of the rotation shaft 4 of the blower fan 3 stops due to a failure or the fan drive belt 13 breaks, etc., the rotation detection device 5
detected by the control unit 16
A cold air stop signal is output from , and its contact Cu is closed. Therefore, interlock relay Xo is activated and normally closed contact _XO2 between terminals _A1 and _A2 is opened, thereby releasing the self-holding of main relay _R4 .
The operation of the DC motor 1 is stopped. As the relay Mg, an electromagnetic contactor, which is normally used to turn the motor on and off, is used, and a thermal relay Th
The electromagnetic switch is combined with an electromagnetic contactor to form an electromagnetic switch, and is intended to protect the motor. Also, the interlock relay Xo operates only when the contact cu mentioned above is closed.
This is also the case when relay Mg returns and closes normally closed contact Mg ₂ .

As mentioned above, the present invention detects the rotation of the rotating shaft of the blower fan using a rotation detection device, and receives a rotation stop signal from the rotation detection device to activate an interlock relay to stop driving the DC motor. Therefore, the cooling air will stop not only when the rotational drive by the fan motor stops, but also when a mechanical failure occurs such as the fan drive belt breaks or the fan's rotating shaft breaks. This has the advantage that when such a situation occurs, it can be reliably detected and the operation of the DC motor can be stopped, and the DC motor can be reliably protected from cooling air stopping.

[Brief explanation of the drawing]

The drawing shows a schematic diagram of an embodiment of the present invention, in which 1 is a DC motor, 2 is a fan motor, 3 is a blower fan,
4 is a rotating shaft, 5 is a rotation detection device, 7 is a control panel, 1
6 is a control unit, 17 is a protection circuit, Mg is a magnetic relay, Mg ₁ is a normally open contact,
Mg ₂ is a normally closed contact, cu is a contact, R ₄ is a main relay,
PB ₁ , PB ₂ , and PB ₃ are push buttons, Xo is an interlock relay, and R ₁ is a relay for DC motor operation.

Claims (1)

[Scope of utility model registration request] It has a relay that operates when a starting switch for the fan motor is turned on to drive the fan motor, and a normally closed contact of the relay and a rotation that detects the rotation of the rotating shaft of the blower fan driven by the fan motor. The interlock relay is connected to the power supply through a parallel circuit with the normally open contact of the control unit that is activated by detection of stoppage, and is energized when the normally open contact of the control unit is closed, and A DC motor that is equipped with a drive circuit that drives the DC motor by the output of the main relay, through which an exciting current flows through the normally closed contacts of an interlock relay when a switch is turned on to start the DC motor, which is forced to blow air by a fan. Motor cooling protection device.