CN203981750U

CN203981750U - Pointer-type safety current table

Info

Publication number: CN203981750U
Application number: CN201420408800.2U
Authority: CN
Inventors: 王余
Original assignee: WENZHOU TIANQI ELECTRICAL APPLIANCES Co Ltd
Current assignee: WENZHOU TIANQI ELECTRICAL APPLIANCES Co Ltd
Priority date: 2014-07-23
Filing date: 2014-07-23
Publication date: 2014-12-03
Anticipated expiration: 2024-07-23

Abstract

The utility model discloses a kind of pointer safety current table, comprise shell and be arranged on the intraware in housing, described intraware comprises coil, is fixed on the pointer on coil and fixes magnet in the enclosure, on described shell, be also provided with positive terminal and negative terminal, between described positive terminal and coil, be electrically connected with temperature monitoring module, described temperature monitoring module comprises: switching tube, temperature sensor.Pointer safety current table of the present utility model, carrys out the break-make of gauge tap pipe by temperature sensor, further reach the effect of controlling break-make between binding post and coil, has effectively reached the effect that prevents coil burnout.

Description

Pointer-type safety current table

Technical field

The utility model relates to a kind of reometer, relates in particular a kind of pointer safety current table.

Background technology

The application of reometer in commercial production, school instruction, infrastructure etc. is very extensive, reometer roughly can be divided into pointer-type and digital two kinds, pointer-type has simple in structure, feature with low cost, digital have an open-and-shut feature of reading, but digital reometer price comparison is expensive, thus in actual life or indicator type current meter use many.

Indicator type current meter is in the market all magneto-electric principle, utilize exactly the cooperation between coil and magnet, be the torsion that coil produces rotation by the intensity-conversion of electric current, then judge the size of electric current by measuring the size of torsion, but reometer is linked into while measuring electric current in circuit, if occur in the smaller situation of access range, the electric current flowing through is greater than maximum constraints electric current, will make like this coil produce in a flash a large amount of heats, cause the temperature in coil sharply to raise, finally burn, and in the process of students in middle and primary schools' experiment, often there will be the problem of wrong range, although there is part digital display type reometer to there is the function of monitoring temperature in prior art, but it needs miniature CPU to control, complex circuit cost is high, so and be not suitable for indicator type current meter with low cost.

Utility model content

The deficiency existing for prior art, the purpose of this utility model is to provide a kind of pointer safety current table with monitoring temperature.

For achieving the above object, the utility model provides following technical scheme: a kind of pointer safety current table, comprise shell and be arranged on the intraware in housing, described intraware comprises coil, is fixed on the pointer on coil and fixes magnet in the enclosure, on described shell, be also provided with positive terminal and negative terminal, between described positive terminal and coil, be electrically connected with temperature monitoring module, described temperature monitoring module comprises:

Switching tube, this switching tube comprises first end, is coupled to positive terminal, and the second end is coupled to negative terminal after being coupled to coil again, and control end, accepts control signal;

Temperature sensor, closely connected coil setting is with the temperature on inductive coil, and one end is coupled to positive terminal, and the other end is coupled to the control end of switching tube with the break-make of gauge tap pipe;

Wherein, in the time that coil temperature rises to certain value, switching tube disconnects the electrical connection between the external world and coil.

By adopting technique scheme; after because of carelessness the range of reometer having been connect little; just have the coil of very large electric current current flowing table inside, thereby on coil, will produce very many heats, the temperature on coil is raise rapidly; will reach at short notice the critical point of temperature sensor; temperature sensor will disconnect by gauge tap pipe like this, effectively stops flowing through the electric current of coil, and the temperature of coil just can not rise again; can effectively protect coil, and with low cost.

The utility model is further set to: described switching tube is NMOS pipe.

By adopting technique scheme, metal-oxide-semiconductor has and cut-offs fireballing advantage, thereby with just can disconnect the electric current that flows through coil here within the extremely short time, just can prevent the temperature continuation rising of coil, effectively protects coil.

The utility model is further set to: described temperature sensor comprises:

Thermo-sensitive resistor, closely connected coil setting is with the temperature on inductive coil, and its one end is coupled to positive terminal, and the other end is coupled to switch controlled end;

Divider resistance, one end is coupled to thermo-sensitive resistor, and the other end is coupled to negative terminal.

By adopting technique scheme, the resistance of thermo-sensitive resistor changes along with the variation of temperature, thereby with here, just can effectively regulate by the mating reaction between thermo-sensitive resistor and divider resistance the voltage that is input to switching tube, so just can effectively reach the effect of the break-make of gauge tap pipe, just can disconnect timely the coil stream that powers on, prevent that coil from burning out because electric current is excessive.

In the utility model embodiment, the NMOS pipe of the low forward voltage such as be AP2300 that switching tube adopts model, thermo-sensitive resistor is positive temperature coefficient (PTC) thermo-sensitive resistor.

Brief description of the drawings

Fig. 1 is the one-piece construction figure of pointer safety current table of the present utility model;

Fig. 2 is the circuit diagram of temperature monitoring module in Fig. 1.

In figure: 1, shell; 11, positive terminal; 12, negative terminal; 2, intraware; 21, coil; 22, pointer; 23, magnet; 3, temperature monitoring module; RW, thermo-sensitive resistor; R, divider resistance; M, switching tube.

Embodiment

In wrong range; the main cause that coil 21 burns is because the excess Temperature on coil 21 causes; thereby the object of utilizing the temperature of monitoring on coil 21 to reach a protection coil 21 compares direct monitoring stream and cross the electric current of coil 21 and have better protective value, and be not easy to occur misoperation.

Shown in Fig. 1, a kind of pointer 22 formula safety current tables of the present embodiment, comprise shell 1 and be arranged on the intraware 2 in housing, described intraware 2 comprises coil 21, is fixed on the pointer 22 on coil 21 and is fixed on the magnet 23 in shell 1, on described shell 1, be also provided with positive terminal 11 and negative terminal 12, between described positive terminal 11 and coil 21, be electrically connected with temperature monitoring module 3, described temperature monitoring module 3 comprises:

Switching tube M, this switching tube M comprises first end, is coupled to after positive terminal 11, the second ends are coupled to coil 21 and is coupled to negative terminal 12 again, control end, accepts control signal;

Temperature sensor, closely connected coil 21 arranges with the temperature on inductive coil 21, and one end is coupled to positive terminal 11, and the other end is coupled to the control end of switching tube M with the break-make of gauge tap pipe M;

Wherein, in the time that certain value is arrived in coil 21 temperature rises, switching tube M disconnects the electrical connection between extraneous and coil 21.

By adopting technique scheme, in the time of careless wrong range, among coil 21, will flow through very large electric current, flow through in the process of coil 21 at electric current, because the effect of coil 21 internal resistances will consume electric current, and the energy consuming will discharge in the mode of heat energy, thereby the surface temperature of coil 21 will constantly rise, at this moment this temperature of temperature sensor Real-Time Monitoring, in the time that temperature reaches critical point, temperature sensor will send a signal to switching tube M, switching tube M will disconnect, because switching tube M is the important channel being communicated with between external cabling post and coil 21, thereby in the time that switching tube M disconnects, will cut off being connected between binding post and coil 21, so the electric current flowing through in coil 21 also can disappear, thereby coil 21 stops heating, temperature also no longer raises, coil 21 just can not burn because of excess Temperature like this.

Below principle of work and the process of above-mentioned mentioned temperature sensor and switching tube M are described in further detail.

As shown in Figure 2, can find out between thermo-sensitive resistor RW and divider resistance R it is the relation that presents a series connection, and the control end of switching tube M is coupled between the two, so the voltage being applied on switching tube M be the voltage on divider resistance R, simultaneously because switching tube M is NMOS pipe, NMOS pipe is positive voltage breakover element, i.e. NMOS pipe conducting in the time that voltage reaches certain value, while being less than this value, NMOS pipe disconnects, so when connecting binding post, when connecing range, because the electric current by coil 21 is not very large, so the temperature on coil 21 is not just very high, and the thermo-sensitive resistor RW that the thermo-sensitive resistor RW that the present embodiment adopts is positive temperature coefficient (PTC), in the time that temperature is higher, resistance is larger, so in the temperature on coil 21 is not high, the resistance of thermo-sensitive resistor RW is not very large, so the voltage of its point is not high yet, so the voltage on divider resistance R will be higher, make switching tube M conducting, reometer is normally worked, in the time being linked into small-range, very large owing to flowing through the electric current of coil 21, so the temperature of coil 21 raises rapidly, so the resistance of thermo-sensitive resistor RW also raises rapidly, its voltage of getting also can transformation, so the voltage on divider resistance R will reduce, in the time being reduced to certain value (being the forward voltage of NMOS pipe), NMOS manages disconnection, will disconnect being connected between binding post and coil 21, so the temperature of coil 21 no longer rises, just there will not be the problem of burning coil 21.

In sum, by the setting of temperature monitoring module 3, in the time that on coil 21, temperature reaches certain value; temperature sensor gauge tap pipe M disconnects; to make coil 21 power-off, the temperature on coil 21 just can not raise again, just can effectively reach the object of protection coil 21.

The above is only preferred implementation of the present utility model, and protection domain of the present utility model is also not only confined to above-described embodiment, and all technical schemes belonging under the utility model thinking all belong to protection domain of the present utility model.It should be pointed out that for those skilled in the art, in the some improvements and modifications that do not depart under the utility model principle prerequisite, these improvements and modifications also should be considered as protection domain of the present utility model.

Claims

1. a pointer safety current table, comprise shell and be arranged on the intraware in housing, described intraware comprises coil, is fixed on the pointer on coil and fixes magnet in the enclosure, on described shell, be also provided with positive terminal and negative terminal, it is characterized in that: between described positive terminal and coil, be electrically connected with temperature monitoring module, described temperature monitoring module comprises:

2. pointer safety current table according to claim 1, is characterized in that: described switching tube is NMOS pipe.

3. pointer safety current table according to claim 1, is characterized in that: described temperature sensor comprises: