CN201336561Y

CN201336561Y - Overload protective device of electric motor

Info

Publication number: CN201336561Y
Application number: CNU2008201777898U
Authority: CN
Inventors: 杨平; 张宝良; 杨国威
Original assignee: BEIJING FENGLONG TECHNOLOGY Co Ltd
Current assignee: Beijing Fenglong Greenhouse Technology Co., Ltd.
Priority date: 2009-08-03
Filing date: 2009-08-03
Publication date: 2009-10-28
Anticipated expiration: 2019-08-03

Abstract

The utility model relates to an overload protective device of an electric motor, comprising a power interface circuit which leads the input direct current supply to be reduced and stabilized for obtaining working power supply; an electric current sample circuit which is serially connected in a power supply circuit of the electric motor; a voltage comparison circuit connected with the power interface circuit and the electric current sample circuit for utilizing sampling voltage output by a voltage reference comparison sampling circuit, and when the sampling voltage is more than the reference voltage, a trigger signal is output; a trigger circuit output by the voltage comparison circuit, witch can turnover and generate a driving signal according to the trigger signal, a drive circuit connected with the trigger circuit, which cuts off the power supply circuit of the electric motor according to the driving signal. The overload protective device is provided with a forward and reverse-direction protecting function, and the overload protective device acts on owning to the relation of the current size of the electric motor, the overload protective device has a restoring function without being affected by factors such as environmental temperature and the like.

Description

The motor overload protection device

Technical field

The utility model relates to a kind of overcurrent protection device, and particularly a kind of motor overload protection device is widely used in the overload protection of the direct current drive machine equipment of every profession and trade, can with the safe operation of supporting use such as motor and protection motor.

Background technology

Electronic film-coiling device protection in for example present known greenhouse does not attract much attention, and perhaps only does protection with fuse.The consequence that we produce from the both of these case analysis: first works as electronic film-coiling device does not have under the situation of protector, if in running, run into faults such as overload, stall, and the safety that will burn out electronic film-coiling device even destroy greenhouse facilities and threaten people.Second works as electronic film-coiling device by under the fuse protection situation, under failure condition, and for different overload situations, the fusing time difference, in time power-off protection equipment may cause motor to damage, even and also can't recover automatically after the fusing.

The utility model content

The purpose of this utility model provides a kind of motor overload protection device that can solve the technological deficiency of above-mentioned prior art existence, and its power input is not subjected to the restriction of electric power polarity, provides two-way overload protective to motor positive and inverse.

Motor overload protection device of the present utility model comprises:

DC power supply to input is carried out step-down, voltage stabilizing to obtain the power interface circuit of working power;

Be serially connected in the current sampling circuit in the motor power supply circuits;

The voltage comparator circuit that connects described power interface circuit and current sampling circuit is used to utilize the relatively sampled voltage of sample circuit output of reference voltage, and when sampled voltage during greater than reference voltage, exports triggering signal;

The circuits for triggering that connect described voltage comparator circuit output, it is according to described triggering signal upset and produce drive signal;

The drive circuit that connects described circuits for triggering, it cuts off the motor power supply circuits according to described drive signal.

Wherein said power interface circuit has a guiding circuit that is suitable for the input voltage change in polarity.Described guiding circuit is a diode bridge.

Wherein said current sampling circuit comprises forward current sampling amplifying circuit and the reverse current sample circuit that is serially connected in the motor power supply circuits.

Wherein said motor power supply circuits are meant from the electric current of dc supply input and flow through behind the motor, flow back into the circuit of another dc supply input.

Wherein said forward current sampling amplifying circuit and reverse current sample circuit have the sampling resistor that is connected in the described motor power supply circuits respectively, and have the amplifier that the sampled signal on the described sampling resistor is amplified.

Wherein said voltage comparator circuit has two comparators that utilize reference voltage respectively the sampled voltage of forward current sample amplifying circuit and reverse current sample circuit output to be compared.

Wherein said circuits for triggering are RS circuits for triggering.

Wherein said drive circuit has a relay switch by transistor driving.The contact of described relay switch is serially connected in the described motor power supply circuits.

The utlity model has following technique effect: possess forward and defencive function in the other direction, and also only relevant during its action with size of current by motor, but have restore funcitons, and be not subjected to the influence of factors such as ambient temperature.

Below in conjunction with accompanying drawing structure of the present utility model and operation principle are elaborated.

Description of drawings

Fig. 1 is circuit theory diagrams of the present utility model;

Fig. 2 is the circuit diagram of the power interface circuit among Fig. 1;

Fig. 3 is the circuit diagram of the forward current sampling amplifying circuit among Fig. 1;

Fig. 4 is the circuit diagram of the reverse current sampling amplifying circuit among Fig. 1;

Fig. 5 is the circuit structure diagram of the voltage comparator circuit among Fig. 1;

Fig. 6 is the circuit structure diagram of the circuits for triggering among Fig. 1;

Fig. 7 is the circuit diagram of the drive circuit among Fig. 1.

Embodiment

The utility model is the overload protection arrangement at the motor that can rotate and reverse; because the polarity of the power supply of motor need change according to the needs of motor forward or reverse, so the utility model has designed the overload protective device that is applicable to this motor especially.Just; the input voltage of overload protective device does not have the polarity restriction, can provide motor rotating both direction current overload to detect, and the overload back in time cuts off equipment such as out-put supply protection motor; after handling equipment fault, shut the input power supply and re-power and can recover.

Fig. 1 has shown the circuit theory diagrams of motor overload protection device of the present utility model, and this motor overload protection device comprises:

DC power supply to input is carried out step-down, the power interface circuit 11 of voltage stabilizing to obtain working power, its main effect is to provide a working power stable and polarity does not change with the input voltage change in polarity to all circuit, the voltage of this working power can be 9 volts, and can be used as the power supply of comparator reference voltage;

Be serially connected in the

current sampling circuit

12 and 16 in the motor power supply circuits;

The voltage comparator circuit 13 that connects described power interface circuit 11 and

current sampling circuit

12 and 16, this voltage comparator circuit 13 utilizes reference voltage relatively

sample circuit

12 and 16 sampled voltage P0 and the P1 that export, and as sampled voltage P0 and P1 during greater than reference voltage, output triggering signal OUT1 and OUT2;

The circuits for triggering 14 that connect described voltage comparator circuit 13 outputs, it is according to described triggering signal OUT1 and OUT2 upset and produce drive signal;

The drive circuit 15 that connects described circuits for triggering 14, it is according to the break-make of described drive signal control motor power supply circuits.

Fig. 2 has shown the particular circuit configurations of the power interface circuit 11 among Fig. 1, wherein P1 is a power input, B1 is the guiding circuit that is suitable for the input voltage change in polarity, VB1 is a decompression device, V1 is a voltage-stabilizing device, the characteristics of this power interface circuit 11 are to be provided with voltage guiding circuit B1, so that adapt to the change in polarity of input voltage.This guiding circuit B1 can be a diode bridge, utilizes the unilateal conduction performance of diode, always the polarity of voltage that its output is maintained fixed, for example among the figure on negative just down polarity, no matter and how input voltage polarity changes.

As shown in Figure 1, current sampling circuit of the present utility model comprises forward current sampling amplifying circuit 12 and the reverse current sample circuit 16 that is serially connected in the motor power supply circuits.Wherein, forward current sampling amplifying circuit 12 is used for just changeing the current overload detection of motor, and the current overload that reverse current sample circuit 16 then is used for motor with reciprocating movement detects.

Motor power supply circuits of the present utility model are meant from the electric current of dc supply input and flow through behind the motor, flow back into the circuit of another dc supply input.For example power so that in the situation that motor is just changeing at forward, the path of motor power supply circuits is: the sub-A_IN of dc supply input → forward current sampling amplifier 12 → drive circuit 15 → terminal A-_IN2 → motor → terminal B_IN1 → reverse current sampling amplifier 16 → sub-B_IN of another dc supply input.Oppositely powering so that in the situation of motor counter-rotating, the path of motor power supply circuits is: the sub-B_IN of the dc supply input → reverse current sampling amplifier 16 → terminal B_IN1 → motor → sub-A_IN of terminal A_IN2 → drive circuit 15 → forward current sampling amplifier 12 → dc supply input.

Fig. 3 and Fig. 4 have shown the circuit structure of forward current sampling amplifying circuit 12 of the present utility model and reverse current sample circuit 16 respectively, these two circuit have sampling resistor R11 and the R21 that is connected in the described motor power supply circuits respectively, and have the amplifier that the sampled signal on described sampling resistor R11 and the R21 is amplified.When electromotor overload, the electric current that flows through sampling resistor increases, and makes that the sampled signal (being voltage drop) on the sampling resistor increases, after amplifying via dual-stage amplifier, and output forward sampled voltage P0 or reverse sampled voltage P1.

Fig. 5 has shown the circuit structure of comparison circuit 13 of the present utility model, and this voltage comparator circuit 13 has two and utilizes reference voltage respectively to the sampled voltage P0 of forward current

sample amplifying circuit

12 and 16 outputs of reverse current sample circuit and comparator U2A and the U2B that P1 compares.As sampled voltage P0 or P1 during greater than reference voltage, comparator U2A or U2B output can be used the output voltage OUT1 or the OUT2 of Power Generation Road 14 upsets, for example+and 9V voltage.

Fig. 6 has shown the circuit structure of circuits for triggering 14 of the present utility model, these circuits for triggering 14 come down to RS circuits for triggering, need be high level during the 6th pin operate as normal of U3, need low level when resetting, wherein NAND gate U3A and U3B constitute a rest-set flip-flop, and diode D1 and D2 receive output signal (voltage) OUT1 and the OUT2 of comparator respectively, when OUT1 or OUT2 are low level, diode D1 or D2 conducting, the input endpoint A that makes trigger is a low level; When OUT1 or OUT2 became high level, diode D1 or D2 ended, and make the input endpoint A of trigger become high level, thereby generated the jump signal that makes the trigger upset, caused drive signal of circuits for triggering 14 outputs.

Fig. 7 has shown the circuit structure of drive circuit 15 of the present utility model, and this drive circuit 15 has a relay switch K who is driven by transistor Q2.The normally closed contact of relay switch K is serially connected in the described motor power supply circuits.When electromotor overload, the drive signal OUT5 of circuits for triggering 14 outputs makes transistor Q2 conducting, and the energising of relay winding disconnects normally closed contact, thereby cuts off the motor power supply circuits, finishes overload protection.As selection, the contact of relay switch K can be a normal opened contact also, when motor does not transship, and transistor Q2 conducting (for example adopt the PNP transistor, perhaps change the polarity of drive signal), relay tip closure; In case overload, transistor Q2 just ends at once, and the indicating relay contact disconnects.

Operation principle of the present utility model is as follows:

After connecting motor, the operating current of motor produces very little pressure drop on sample resistance, compare through amplifier amplification back and reference voltage, when electronic overload, the input voltage of comparator is greater than reference voltage, comparator output high level goes to trigger the rest-set flip-flop counter-rotating, makes it to cut off out-put supply through overdriving.

The utility model adopts the electronic overload protector, possesses forward and defencive function in the other direction, and only relevant with the size of current by motor during its action, but has restore funcitons, and is not subjected to the influence of factors such as ambient temperature.

Claims

1, a kind of motor overload protection device is characterized in that comprising:

DC power supply to input is carried out step-down, the power interface circuit (11) of voltage stabilizing to obtain working power;

Be serially connected in the current sampling circuit (12,16) in the motor power supply circuits

Connect described power interface circuit (11) and current sampling circuit (12,16) voltage comparator circuit (13), be used to utilize relatively sample circuit (12 of reference voltage, 16) Shu Chu sampled voltage (P0, P1), and when sampled voltage (P0 is during P1) greater than reference voltage, the output triggering signal (OUT1, OUT2);

The circuits for triggering (14) that connect described voltage comparator circuit (13) output, it is according to described triggering signal (OUT1, OUT2) upset and generation drive signal;

The drive circuit (15) that connects described circuits for triggering (14), it cuts off the motor power supply circuits according to described drive signal.

2, motor overload protection device according to claim 1 is characterized in that described power interface circuit (11) has a guiding circuit (B1) that is suitable for the input voltage change in polarity.

3, motor overload protection device according to claim 2 is characterized in that described guiding circuit (B1) is a diode bridge.

4, motor overload protection device according to claim 1 is characterized in that described current sampling circuit comprises forward current sampling amplifying circuit (12) and the reverse current sample circuit (16) that is serially connected in the motor power supply circuits.

5, motor overload protection device according to claim 4 is characterized in that described motor power supply circuits are meant from the electric current of dc supply input to flow through behind the motor, flow back into the circuit of another dc supply input.

6, motor overload protection device according to claim 4; it is characterized in that described forward current sampling amplifying circuit (12) and reverse current sample circuit (16) have the sampling resistor (R11 that is connected in the described motor power supply circuits respectively; R21); and have described sampling resistor (R11, R21) amplifier that amplifies of the sampled signal on.

7, motor overload protection device according to claim 6; it is characterized in that described voltage comparator circuit (13) has two and utilizes reference voltage respectively to the sampled voltage (P0 of forward current sample amplifying circuit (12) and reverse current sample circuit (16) output; the comparator that P1) compares (U2A, U2B).

8, motor overload protection device according to claim 1 is characterized in that described circuits for triggering (14) are the RS circuits for triggering.

9, motor overload protection device according to claim 1 is characterized in that described drive circuit (15) has a relay switch by transistor driving.

10, motor overload protection device according to claim 9 is characterized in that the contact of described relay switch is serially connected in the described motor power supply circuits.