CN112596011A

CN112596011A - Method and circuit for measuring release time of electromagnet of brake sucker

Info

Publication number: CN112596011A
Application number: CN202011504678.5A
Authority: CN
Inventors: 刘铁兵; 易红宝; 于洁云
Original assignee: Shenzhen Zanty Motor Co ltd
Current assignee: Shenzhen Zanty Motor Co ltd
Priority date: 2020-12-18
Filing date: 2020-12-18
Publication date: 2021-04-02

Abstract

The invention discloses a method and a circuit for measuring the release time of a brake sucker electromagnet, wherein the method comprises the following steps: connecting the electromagnet of the brake sucker into a measuring circuit; the switch circuit is conducted to electrify the whole measuring circuit, and the current waveform of the electromagnet of the brake sucker is displayed on the oscilloscope; turning off the switch circuit, acquiring the position of the current waveform starting to descend from the straight section, and taking the time of the starting to descend position as the timing starting time; acquiring at least one position on the current waveform, which descends from a straight section and then ascends to the highest position, and taking the time of a middle point of the at least one highest position as a timing end time; and subtracting the timing starting time from the timing ending time to obtain the release reaction time length of the electromagnet of the brake sucker. The invention has the advantages of simple, quick and visual measurement of the release time of the electromagnet of the brake sucker and low cost.

Description

Method and circuit for measuring release time of electromagnet of brake sucker

Technical Field

The invention relates to the technical field of electromagnet measurement of a sucking disc, in particular to a method and a circuit for measuring release time of an electromagnet of a brake sucking disc.

Background

The electromagnet of sucking disc type is a special type of electromagnet, and the requirement on the release time is very important, for example, when the electromagnet is applied to an electromagnetic brake on an automobile brake, the electromagnet of the braking sucking disc is arranged in the electromagnet, and the electromagnet of the braking sucking disc applied to the automobile requires that the electromagnet must respond quickly and brake timely so as to ensure the safety of automobile drivers.

As shown in fig. 1, the electromagnetic brake includes a brake chuck electromagnet and a brake part connected with the chuck electromagnet, the brake part includes a brake pad, a brake drum and a fixing plate, the brake chuck electromagnet is fixedly connected with the brake part through a connecting screw, and the fixing plate installs the whole electromagnetic brake at a wheel position.

The brake sucker electromagnet comprises a metal sucker shell and a coil arranged in the sucker shell, and the end face of the sucker shell is connected with an armature through a spring.

After the coil is electrified, the sucker shell becomes a large magnet which is integrated, due to magnetic force, the end face of the sucker shell draws the armature close to attract, the spring is in a compressed state, and at the moment, the armature is separated from the brake pad, so that the wheel can rotate.

Because the coil is an inductive storage element, after power failure, the current on the coil is not immediately reduced to zero, so that the current still passes through the coil in a short time after the power failure, the sucker shell still has magnetism to attract the armature, but because the current is reduced until the current is slowly reduced to zero, the attraction of the sucker shell is weakened, when the attraction of the sucker shell is smaller than the reverse elasticity of the spring, the armature is bounced off and separated from the end face of the sucker shell, and the armature is separated from the sucker shell and then is in close contact with the brake pad under the action of the elasticity, so that the braking effect is achieved.

The time that the armature breaks away from the sucker shell to play a braking role after the electromagnetic brake is powered off is called the releasing time of the electromagnet of the brake sucker, namely the reaction time length of the electromagnet of the brake sucker for releasing the armature. The release reaction time length of the electromagnet of the brake sucker is a key parameter for judging whether the electromagnet of the brake sucker is qualified or not. Therefore, the measurement of the release reaction time length before the brake sucker electromagnet leaves the factory is an important test procedure.

But what the release reaction time length of current brake sucking disc electro-magnet measured adopts is plus the motor, lets the motor rotatory, then measures when brake sucking disc electro-magnet and brake the motor and obtain release reaction time length, and whole device structure is complicated to need dispose one set of complicated system and cooperate the execution, measure inconvenient, swift, measurement efficiency is low and with high costs.

Therefore, the prior art has yet to be improved.

Disclosure of Invention

In view of the defects of the prior art, the invention aims to provide a method and a circuit for measuring the release time of a brake sucker electromagnet, and aims to enable the release time of the brake sucker electromagnet to be simple, quick, intuitive and low in cost.

In order to realize the purpose, the invention adopts the following technical scheme:

a method for measuring the release time of an electromagnet of a brake chuck comprises the following steps:

s10, connecting the electromagnet of the brake sucker into a measuring circuit, wherein the measuring circuit comprises a power supply, a switching circuit and a current sensor which are arranged in series, and further comprises an oscilloscope connected with the current sensor;

s20, the switch circuit is conducted to electrify the whole measuring circuit, and the current waveform of the brake sucker electromagnet is displayed on the oscilloscope;

s30, turning off the switch circuit, obtaining the position of the current waveform which starts to descend from the straight section, and taking the time of the position which starts to descend as the timing starting time;

s40, acquiring at least one position of the current waveform, wherein the position is descended from the straight section and then ascends to the highest position, and taking the time of the middle point of the at least one highest position as the timing end time;

and S50, subtracting the timing starting time from the timing ending time to obtain the release reaction time length of the electromagnet of the brake sucker.

Wherein, in step S40:

when only one highest position exists, the highest position is regarded as a middle point, the time of the middle point is regarded as the timing end time,

when there are a plurality of the highest positions, the time at the midpoint of the plurality of the highest positions is set as the timing end time.

And the current waveform data of the brake sucker electromagnet is calculated and analyzed by adopting intelligent electronic equipment, and the release reaction time length of the brake sucker electromagnet is displayed.

The measuring circuit further comprises a release circuit which is arranged between the power supply and the brake sucker electromagnet in parallel and used for providing a current release loop for the brake sucker electromagnet after power failure.

The switching circuit is composed of a waveform generator and an MOS tube, and the MOS tube is connected in series in the measuring circuit and is controlled to be switched on and off by the waveform generator.

The invention also provides a circuit for measuring the release time of the electromagnet of the brake sucker, wherein the circuit measures the release reaction time length of the electromagnet of the brake sucker by adopting the method, and the measuring circuit comprises:

the braking sucker electromagnet is connected with the measuring circuit and then is connected with the power supply, the switching circuit and the current sensor in series, and the oscilloscope acquires the current in the process from power-off to complete release of the braking sucker electromagnet and displays the waveform of the current.

The switching circuit comprises a waveform generator and an MOS (metal oxide semiconductor) tube, wherein the MOS tube is connected in series in the measuring circuit and is controlled to be switched on and off by the waveform generator.

Wherein the waveform generator is a square wave generator.

The release circuit is a freewheeling diode connected in parallel between the power supply and the brake sucker electromagnet.

According to the method for measuring the release time of the electromagnet of the brake sucker, the current waveform of the electromagnet of the brake sucker after power failure is obtained by using the oscilloscope, the time of the position starting to descend from the straight section and the time of the position descending from the straight section and then ascending to the highest position are obtained on the current waveform, and the time of the position starting to descend from the straight section and then ascending to the highest position are obtained, so that the release reaction time length of the electromagnet of the brake sucker is obtained by subtracting the current waveform and the time.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the structures shown in the drawings without creative efforts.

FIG. 1 is a schematic structural diagram of a brake chuck electromagnet used in an electromagnetic brake according to the present invention;

FIG. 2 is a schematic flow chart illustrating a method for measuring a release time of an electromagnet of a brake chuck according to a first embodiment of the present invention;

FIG. 3 is a schematic diagram of a first embodiment of a brake chuck electromagnet release time measuring circuit according to the present invention;

FIG. 4 is a schematic circuit diagram illustrating the specific circuit connection of the brake chuck electromagnet release time measuring circuit according to the present invention;

FIG. 5 is a schematic diagram of a current waveform if the armature is not released after de-energizing;

fig. 6 is a schematic diagram of the current waveform after the electromagnet of the brake sucker is powered off until the armature is completely released.

Description of reference numerals:

100-brake sucker electromagnet, 200-measuring circuit, 1-power supply, 2-switching circuit, 21-waveform generator, 22-MOS tube, 3-current sensor, 4-oscilloscope and 5-release circuit.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

It should be noted that all the directional indicators (such as up, down, left, right, front, and rear … …) in the embodiment of the present invention are only used to explain the relative position relationship between the components, the movement situation, etc. in a specific posture (as shown in the drawing), and if the specific posture is changed, the directional indicator is changed accordingly.

In the present invention, unless expressly stated or limited otherwise, the terms "connected," "secured," and the like are to be construed broadly, and for example, "connected" may be fixedly connected, detachably connected, or integrally formed; can be mechanically or electrically connected; they may be directly connected or indirectly connected through intervening media, or they may be connected internally or in any other suitable relationship, unless expressly stated otherwise. The specific meanings of the above terms in the present invention can be understood by those skilled in the art according to specific situations.

In addition, the descriptions related to "first", "second", etc. in the present invention are only for descriptive purposes and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one such feature.

Referring to fig. 2, the present invention provides a method for measuring the release time of an electromagnet of a brake chuck; the process comprises the following steps:

and S10, connecting the brake sucker electromagnet 100 to the measuring circuit 200, wherein the measuring circuit 200 comprises a power supply 1, a switching circuit 2 and a current sensor 3 which are arranged in series, and further comprises an oscilloscope 4 connected with the current sensor 3, and the brake sucker electromagnet 100 is connected to the measuring circuit 200 and then connected with the power supply 1, the switching circuit 2 and the current sensor 3 in series.

Preferably, as shown in fig. 3, in the measuring circuit 200 of the present invention, the output end (positive pole) of the power supply 1 is connected to the input end of the current sensor 3, a measuring access point is provided between the output end of the current sensor 3 and the input end of the switching circuit 2 for accessing the brake pad electromagnet 100 with measurement, and the output end of the switching circuit 3 is connected to the input end (negative pole) of the power supply 1.

That is, when the present invention measures the brake pad electromagnet 100, it is only necessary to connect the brake pad electromagnet 100 to the measurement circuit 200 of the present invention.

The power supply 1 of the present invention may use a dc regulated power supply.

And S20, the switch circuit 2 is turned on to electrify the whole measuring circuit 200, and the current waveform of the brake pad electromagnet 100 is displayed on the oscilloscope 4.

Because current sensor 3 is connected in series with brake pad electromagnet 100, changes in current on current sensor 3 reflect changes in current to brake pad electromagnet 100. The current sensor 3 sends the acquired current signal to the oscilloscope 4, and the oscilloscope 4 analyzes and processes the data sent by the current sensor 3 to obtain a current waveform diagram, such as the current waveform diagrams shown in fig. 5 and 6.

S30 turns off the switch circuit 2, obtains the position where the current waveform starts to fall from the straight section, and sets the time at the position where the current waveform starts to fall as the start time of the timer.

Before the circuit is switched off, the electromagnet 100 of the brake sucker is in a stable attraction state, and the current on the electromagnet is a stable value, so that the current waveform curve on the oscilloscope is a straight line.

When the switching circuit 2 is turned off, the power supply 1 no longer outputs current. The brake pad electromagnet 100 is an inductive element on which the current does not drop to zero immediately, but decreases gradually until it is zero, so that the current waveform turning off the switching circuit 2 exhibits a gradually decreasing curve, as shown in fig. 5 and 6.

The position where the current waveform starts to fall from the straight section is the starting time of the circuit power failure, but due to the inductance of the brake pad electromagnet 100, the armature on the current waveform is not released immediately, so that the current waveform is taken as the starting time T1 of the reaction time length of the brake pad electromagnet 100 releasing the armature.

And S40, acquiring at least one position on the current waveform, wherein the position is descended from the straight section and then ascends to the highest position, and taking the time of the middle point of the at least one highest position as the timing end time.

And when the power is off, the current of the coil in the sucker shell is gradually weakened, the suction force of the sucker shell to the armature is weakened, and when the reverse elasticity of the spring is greater than the suction force, the armature is bounced off and is separated from the end face of the sucker shell. Before the separation, the armature and the sucker shell are attracted to form a common magnetic field, after the armature is bounced, the magnetic field generates sudden change, the coil can block the sudden change of the magnetic field to generate induced current for increasing the magnetic field, an upward curve can be generated behind an original descending curve on the current waveform of the oscilloscope at the moment, and when the current curve rises to the highest point, the armature and the sucker shell are completely separated, as shown in fig. 6. The highest point may be only one, or a plurality of highest points having the same value may be possible.

If, after power is lost, an external force is used to block the armature within the brake cup electromagnet 100 so that the armature does not disengage from the cup housing and is not released, the waveform of the coil current within the brake cup electromagnet 100 is ultimately as shown in fig. 5 without a curve that falls and then rises.

Preferably, in the measurement method of the present invention, when there is only one highest position, the highest position is regarded as an intermediate point, and the time of the intermediate point is regarded as a timing end time; when there are a plurality of the highest positions, the time at the midpoint of the plurality of the highest positions is set as the timing end time.

When a plurality of highest positions with the same value exist, the curve of the ascending section is a short straight line at the highest position and then begins to descend again.

And S50, subtracting the timing starting time from the timing ending time to obtain the release reaction time length of the brake sucker electromagnet 100.

As shown in fig. 6, the release response time length T of the brake pad electromagnet 100 can be obtained by subtracting T1 from T2. The whole measuring process is simple and quick, and the measuring circuit is simple and easy to realize.

The oscilloscope 4 can directly and automatically subtract the selected T2 and T1 values after setting to obtain T and display the T on the oscilloscope 4, so that a tester can obtain a result very intuitively and the testing efficiency is improved.

The principle of the measuring method of the invention is as follows:

the coil in the electromagnet 100 acts as an inductive element, and after the test circuit 200 is powered off, the current does not drop directly from the original operating current to "zero", but rather, it tends to slowly drop due to the inductive nature of the coil. However, since the armature is finally separated from the chuck by the force of the spring due to the weakening of the magnetic force, and at this time, the magnetic field of the chuck is greatly changed due to the separation of the armature, according to the electromagnetic field theory of maxwell, an induced voltage is generated by the coil of the electromagnet 100 for braking the chuck, and according to the corrugated theorem, when the magnetic field strength is reduced, the direction of the induced current generated by the coil is the direction of trying to increase the original magnetic field, so that the coil of the electromagnet 100 for braking the chuck theoretically generates a current rise at this time. According to the measuring method, the oscilloscope 4 is used for observing the highest point of the rising edge, the release time point of the brake sucker electromagnet 100 is obtained, the reaction time length of the brake sucker electromagnet 100 for releasing the armature iron can be obtained after the time point is subtracted from the power-off time point, and then the reaction time length of the release is compared with a standard reference value, so that whether the brake sucker electromagnet 100 is qualified or not is judged.

Compared with the prior art that the brake sucker electromagnet 100 is externally connected with the motor, and then the length of the release reaction time is calculated by detecting the stop time of the rotation of the motor after the brake sucker electromagnet 100 is powered off, the measuring method provided by the invention is simple, rapid and visual, and saves the test cost.

Preferably, in the method of the present invention, the current waveform data of the brake pad electromagnet 100 is calculated and analyzed by using an intelligent electronic device, and the release response time length of the brake pad electromagnet is displayed. The intelligent electronic equipment can be a mobile phone, a computer and the like, current waveform data are led into the mobile phone, and whether the product is qualified or not is directly displayed after the current waveform data are analyzed, calculated and compared by programs in the mobile phone and the computer after the current waveform data are processed by the computer, so that the measurement efficiency is further improved.

As shown in fig. 5, the present invention further provides a brake pad electromagnet release time measuring circuit 200, which measures the release response time length of the brake pad electromagnet 100 by using the above method, wherein the measuring circuit 200 includes:

the braking sucker electromagnet 100 is connected with the measuring circuit and then is connected with the power supply 1, the switching circuit 2 and the current sensor 3 in series, the oscilloscope 4 acquires the current of the braking sucker electromagnet 100 in the process from power-off to complete release and displays the waveform of the current. Since the current waveform can reflect the time of power-off and the time of releasing the armature from the brake pad electromagnet 100, the length of the release response time of the brake pad electromagnet 100 can be calculated from the current waveform.

Preferably, as shown in fig. 6, in the measurement circuit 200 of the present invention, the switch circuit 2 includes a waveform generator 21 and a MOS transistor 22, and the MOS transistor 22 is connected in series in the measurement circuit 200 and is controlled to be turned on or off by the waveform generator 21.

The waveform generator 21 is powered by the power supply 1, the output end of the waveform generator is connected to the G grid of the MOS tube 22, a pulse signal is output to control the on-off of the MOS tube 22, the D drain electrode of the MOS tube 22 is connected with the output end of the brake sucker electromagnet 100, and the S source electrode of the MOS tube 22 is connected with the negative electrode of the power supply 1, so that the on-off of the MOS tube 22 can control the on-off of the loop of the brake sucker electromagnet 100. In the measuring circuit of the present invention, a voltage limiting resistor R2 is connected between the output terminal of the waveform generator 21 and the G gate of the MOS transistor 22 to provide a suitable on-state voltage.

Preferably, the waveform generator 21 is a square wave generator. The square wave signal sent by the square wave generator makes the MOS tube 22 turn off and on quickly.

Further, the measuring circuit 100 of the present invention further includes a release circuit 5 connected in parallel between the power supply 1 and the brake pad electromagnet 100, and configured to provide a current release loop for the brake pad electromagnet 100 after power failure. The release circuit 5 can accelerate the time for releasing the armature of the brake sucker electromagnet 100 and shorten the release reaction time length T of the brake sucker electromagnet 100.

Preferably, the release circuit 5 of the present invention is a freewheeling diode D1 connected in parallel between the power supply 1 and the brake pad electromagnet 100.

According to the method and the circuit 200 for measuring the release time of the brake sucker electromagnet, provided by the embodiment of the invention, the current waveform of the brake sucker electromagnet 100 after power failure is obtained by using the oscilloscope 4, the time of the position starting to descend from the straight section and the time of the position descending from the straight section and then ascending to the highest position are obtained on the current waveform, and the time of the release reaction time of the brake sucker electromagnet 100 is obtained by subtracting the time of the position starting to descend from the straight section and the time of the position ascending to the highest position.

The above description is only a preferred embodiment of the present invention, and is not intended to limit the scope of the present invention, and all modifications and equivalents of the present invention, which are made by the contents of the present specification and the accompanying drawings, or directly/indirectly applied to other related technical fields, are included in the scope of the present invention.

Claims

1. A method for measuring the release time of an electromagnet of a brake chuck is characterized by comprising the following steps:

2. The brake pad electromagnet release time measuring method according to claim 1, wherein in step S40:

3. The method for measuring the release time of the electromagnet of the brake chuck according to claim 1, wherein the current waveform data of the electromagnet of the brake chuck is calculated and analyzed by an intelligent electronic device, and the release reaction time length of the electromagnet of the brake chuck is displayed.

4. The method of claim 1, wherein the measuring circuit further comprises a release circuit connected in parallel between the power source and the brake pad electromagnet for providing a current release circuit for the brake pad electromagnet after a power failure.

5. The method as claimed in claim 1, wherein the switching circuit comprises a waveform generator and a MOS transistor connected in series in the measuring circuit and controlled by the waveform generator.

6. A brake pad electromagnet release time measurement circuit for measuring the length of the release response time of a brake pad electromagnet using the method of any one of claims 1-5, said measurement circuit comprising:

7. The brake pad electromagnet release time measurement circuit of claim 6,

the switching circuit comprises a waveform generator and an MOS tube, wherein the MOS tube is connected in series in the measuring circuit and is controlled to be switched on and off by the waveform generator.

8. The brake pad electromagnet release time measurement circuit of claim 7, wherein the waveform generator is a square wave generator.

9. The brake chuck electromagnet release time measurement circuit of claim 6, further comprising a release circuit disposed in parallel between the power source and the brake chuck electromagnet for providing a current release circuit for the brake chuck electromagnet after a power outage.

10. A brake pad electromagnet release time measurement circuit according to claim 9, wherein the release circuit is a freewheeling diode connected in parallel between the power supply and the brake pad electromagnet.