CN108001438A - A kind of method for exhausting of braking system of electric car - Google Patents

Abstract

The invention discloses a method for exhausting the brake system of an electric vehicle. The brake pedal is stepped on first, so that the air in the brake circuit is accumulated at the installation hole of the air release screw, and the pressure of the brake circuit is increased, and at this time, the brake pedal is opened. Vacuum pump to vacuum the detection chamber; then pump the air mixed with brake fluid in the brake circuit into the detection chamber; then drive the pressurized plunger in the detection chamber to gradually increase the pressure in the detection chamber; if the detection chamber If the pressure is greater than or equal to the set value, it means that the proportion of brake fluid in the detection chamber is relatively high, which proves that the exhaust of the brake circuit is sufficient. At this time, the exhaust procedure can be ended, and the brake fluid in the detection chamber is pumped One liquid storage cavity; otherwise, repeat the above procedure until fully exhausted. The invention can realize single-person operation, thereby improving efficiency, and can accurately control the exhaust program to ensure thorough exhaust and avoid excessive exhaust.

Description

A method for exhausting the braking system of an electric vehicle

technical field

The invention relates to the technical field of electric vehicle manufacturing, in particular to an exhaust method for a braking system of an electric vehicle.

Background technique

The braking system of an electric vehicle is usually a brake fluid tank that is filled with brake fluid, a brake master cylinder, a front brake wheel cylinder that controls the front brakes, a rear brake wheel cylinder that controls the rear brakes, a A closed system consisting of hydraulic regulators for hydraulic fluid, brake lines connected between the two components, and other components. When working, the basically incompressible brake fluid moves in the circuit of the system, stepping on the brake pedal, and through the boosting effect of the vacuum booster, the brake master cylinder pushes the brake fluid to move in the circuit, and then pushes the front brake The moving wheel cylinder and the rear brake wheel cylinder move, and the front and rear brakes work to generate braking torque. We know that air has compressible characteristics, so once there is air in the closed circuit system of the brake system, the air in the circuit will be compressed first when braking, and then the brake fluid can be pushed to move, which will Cause the loss of the brake pedal travel, thereby increasing the braking reaction time, and reducing the output of the braking force, resulting in serious safety hazards.

For this reason, according to the situation of actual test, people set corresponding air-relieving screw in suitable position in the closed braking circuit. When the brake pedal is stepped on for many times, the air in the circuit will gradually flow and gather at the position where the air release screw is set. At this time, the air release screw can be opened to release the gas mixed with the brake fluid.

In the prior art, people will discharge the air in the closed circuit of the braking system to the outside through various methods, and the most commonly used method is to cooperate with two operators, one of whom is constantly stepping on the brake pedal in the cab. move the pedal so that the air in the circuit gathers together and moves to the place where the bleed screw is set, then keep the brake pedal depressed and the brake circuit maintains a high pressure state, and another person releases the air in the brake circuit under the vehicle body When the air screw is opened, the air mixed with the brake fluid in the brake circuit will be discharged to form air bubbles. The degassing procedure can be completed when there are no more air bubbles to be observed by the naked eye. Although this method does not require a special device, it has the following defects: on the one hand, it needs two people to cooperate with the operation, so its efficiency is low; on the other hand, the brake fluid is corrosive, so it will cause adverse effects on the health of operators influences. In particular, this method requires the operator to have rich experience, and the two persons should cooperate well, otherwise, the problem of incomplete exhaust or excessive exhaust will easily occur.

A kind of "exhaust device of vehicle brake system" is disclosed in the Chinese patent literature, and its announcement number is CN203047242U. The vehicle brake system includes a brake cylinder with an oil discharge port; the exhaust device includes a transparent air pump. A manual control switch and a suction pipe are connected in series in the start-stop control circuit of the suction pump. The suction pipe has a first end connected to the inlet side of the suction pump and a second end for connecting to an oil drain. When exhausting, start the air extraction pump, observe the situation in the transparent air extraction pipe, if the brake fluid has flowed out, it means that the exhaust is completed, and the air extraction pump can be turned off.

However, the above-mentioned exhaust device still has the following defects: First, the exhaust gas through the exhaust device still needs two people to cooperate, in other words, it needs to be stepped on the brake pedal repeatedly by one person, so that the air in the brake circuit is accumulated Go to the deflation screw, and another person observes the condition of the exhaust pipe. Secondly, it is difficult for the operator to accurately determine the exhaust status by observing the condition of the exhaust pipe, and the problem of incomplete exhaust or excessive exhaust is likely to occur.

Contents of the invention

The purpose of the present invention is to solve the problems of low efficiency and difficult to control accurately in the existing exhaust method of the electric vehicle braking system, and to provide an exhaust method for the electric vehicle braking system, which can realize single-person operation, thereby improving efficiency, and the exhaust program can be accurately controlled to ensure thorough exhaust and avoid excessive exhaust.

In order to achieve the above object, the present invention adopts the following technical solutions:

A method for exhausting a braking system of an electric vehicle, comprising the steps of:

a. Connect one end of the air extraction pipe with the third electromagnetic valve to a detection cylinder with a detection chamber, and connect the connector at the other end of the air extraction pipe to the installation hole of the air release screw of the brake system;

b. Use pipelines to connect the suction port of a vacuum pump to the detection chamber of the detection cylinder and the liquid storage chamber that can store brake fluid, and set the first electromagnetic valve on the pipeline connecting the vacuum pump and the liquid storage chamber. A second solenoid valve is arranged on the pipeline of the detection chamber, the detection chamber and the liquid storage chamber are connected by a suction pipe, and a fourth solenoid valve is arranged on the suction pipe;

c. Step on the brake pedal repeatedly to make the air in the brake circuit gather at the installation hole of the air release screw of the brake circuit, and then continue to step on the brake pedal to make the pressure of the brake circuit rise gradually. The hydraulic sensor on the suction pipe between the three solenoid valves and the connector outputs a signal to the control device;

d. When the pressure of the brake circuit is greater than or equal to 3 MPa, the control device opens the second solenoid valve, and turns on the vacuum pump to vacuumize the detection chamber in the detection cylinder, and then closes the second solenoid valve;

e. The control device opens the third solenoid valve, and the air mixed with brake fluid in the brake circuit enters the detection chamber through the exhaust pipe;

f. The control device closes the third electromagnetic valve, and then starts a driving device to push the pressurized plunger at one end of the detection chamber to move, so that the pressure of the air mixed with brake fluid in the detection chamber gradually rises. The hydraulic sensor on the cylinder outputs the pressure signal in the detection chamber to the control device;

g. When the driving device drives the pressurized plunger to move in place, the control device records the highest pressure signal value P in the detection chamber, and then the control device opens the fourth solenoid valve and the first solenoid valve, and the vacuum pump forms a negative pressure in the liquid storage chamber. Pressure, so that a pressure difference is formed between the negative pressure liquid storage chamber and the high pressure detection chamber, and the brake fluid in the detection chamber flows into the liquid storage chamber through the suction pipe;

h. The control device compares the highest pressure signal value P with the pre-stored set value P ₀ and makes a judgment. If P is greater than or equal to P ₀ at this time, the exhaust procedure will end; if this P is less than P ₀ , repeat Step c to step g.

The exhaust method of the present invention gathers the air in the brake circuit to the air release screw by stepping on the brake pedal repeatedly, and then makes the detection chamber form a negative pressure through a vacuum pump, so that the air at the air release screw and a small amount of braking The dynamic liquid is sucked into the detection chamber together, and then the gas-liquid mixture in the detection chamber is pressed by the fixed distance movement of the pressurized plunger, so that the gas-liquid ratio in the detection chamber can be judged by the pressure rise of the detection chamber. Then confirm whether the air in the brake circuit has been completely exhausted, so that one person can achieve efficient exhaust, and at the same time, can accurately judge the exhaust effect to avoid insufficient exhaust or excessive exhaust.

Preferably, the drive device includes an outer sleeve connected to the pressurized plunger, a drive screw is threaded inside the outer sleeve, and one end of the drive screw protruding from the outer sleeve is coaxially connected with the output shaft of the motor, and the motor Electrically connected with the control device, the outer wall of the outer sleeve is provided with an axial limit card slot, and the end of the detection cylinder is provided with a limit protrusion that is locked in the limit card slot. When driving the device, the control device starts the motor, and the motor drives the driving screw to rotate, thereby driving the outer casing threaded with it to move axially, and then driving the pressure plunger to move in the detection chamber.

The motor works to drive the driving screw to rotate. Since the outer casing cannot rotate due to the limit of the limit protrusion, the driving screw can drive the outer casing threaded with it to reciprocate in the axial direction, and then drive the pressurizing plunger to move.

As a preference, a liquid return pipe extending into the bottom of the liquid storage chamber is vertically provided on the top of the liquid storage chamber, one end of the liquid suction pipe is connected to the end of the detection cylinder away from the pressure plunger, and the other end of the liquid suction pipe is It is connected to the upper end of the liquid return pipe, and the air extraction pipe is connected to the side wall of the detection cylinder, and the detection cylinder is provided with a position sensor for detecting the position of the pressurized plunger, and the steps are added in step g as follows: The control device moves the pressurized plunger to the end of the detection chamber close to the suction pipe through the driving device, so that the brake fluid mixed with air in the detection chamber flows into the liquid storage chamber, and the position sensor outputs a position signal to the control device at this time , the control device makes the pressurizing plunger reversely move and reset through the driving device.

In the present invention, a liquid return pipe inserted to the bottom is provided in the liquid storage chamber, so that when the vacuum pump makes the liquid storage chamber form a negative pressure, the brake fluid entering the liquid storage chamber from the liquid suction pipe can be prevented from being sucked out by the vacuum pump. The air in the mixture of brake fluid and air entering the liquid storage chamber through the liquid return pipe will be quickly released to the upper space of the liquid storage chamber under the action of negative pressure in the liquid storage chamber, so as to achieve good gas-liquid separation . In particular, when the present invention pumps the brake fluid in the detection chamber into the liquid storage chamber, the driving device can drive the pressurized plunger to move through the control device to push the brake fluid, thereby ensuring the brake fluid in the detection chamber. The liquid is completely transferred to the reservoir chamber.

Therefore, the present invention has the following beneficial effects: single-person operation can be realized, thereby improving efficiency, and the exhaust program can be accurately controlled to ensure thorough exhaust and avoid excessive exhaust.

Description of drawings

Fig. 1 is a schematic structural view of the exhaust device of the present invention.

In the figure: 1. Vacuum pump 2, liquid storage chamber 21, liquid return pipe 3, detection cylinder 31, detection chamber 32, pressurizing plunger 33, limit protrusion 40, first solenoid valve 41, second solenoid valve 42 , the third electromagnetic valve 43, the fourth electromagnetic valve 5, the motor 51, the driving screw 52, the outer sleeve 521, the limit card slot 6, the air extraction pipe 61, the connector 7, and the liquid extraction pipe.

Detailed ways

The present invention will be further described below in conjunction with the accompanying drawings and specific embodiments.

A method for exhausting the brake system of an electric vehicle, using the exhaust device shown in Figure 1, the exhaust device includes a control device with a logic controller, a vacuum pump 1, a liquid storage chamber 2, and a cylindrical detection cylinder Body 3. There is a cylindrical detection chamber 31 in the detection cylinder. One suction port of the vacuum pump is connected to the liquid storage chamber through a pipeline, and the other suction port of the vacuum pump is connected to the side of the detection chamber of the detection cylinder through a pipeline. Pass. Set a first electromagnetic valve 40 on the pipeline connecting the vacuum pump and the liquid storage chamber to control the on-off of the pipeline; set a second electromagnetic valve 41 on the pipeline connecting the vacuum pump and the detection chamber to control the on-off of the pipeline .

In addition, a pressurized plunger 32 is set in the detection chamber at one end of the detection cylinder, and the pressurized plunger is associated with a driving device whose power source is a motor 5, so that the control device can drive The motor of the device controls the left and right movement of the pressurized plunger. The side of the other end of the detection cylinder away from the pressurized plunger is provided with a suction pipe 6 connected to the detection chamber, and the other end of the suction pipe is provided with a connector 61 that can be connected to the mounting hole of the air release screw of the braking system. A third electromagnetic valve 42 which can be controlled to be switched on or off is arranged on the exhaust pipe.

In addition, the liquid storage chamber and the detection chamber are connected through a liquid suction pipe 7, and a fourth electromagnetic valve 43 that can be controlled to be turned on and off is arranged on the liquid suction pipe. Of course, we also need to set hydraulic sensors capable of sensing internal pressure on the exhaust pipe and the detection chamber, and the control device is electrically connected to the vacuum pump, the motor of the drive device, and the first, second, third, and fourth solenoid valves, and A start switch is arranged on the control device.

The exhaust method of the electric vehicle brake system specifically includes the following steps:

a. Connect one end of the exhaust pipe to a detection cylinder, the exhaust pipe communicates with the detection chamber in the detection cylinder, and a third solenoid valve that can control on-off is provided on the exhaust pipe, and the exhaust pipe The connector at the other end is connected with the air release screw installation hole of the brake system;

b. Connect the first suction port of a vacuum pump with the detection chamber of the detection cylinder with a pipeline, and at the same time connect the second suction port of the vacuum pump with the liquid storage chamber where the brake fluid can be stored. Of course, the pipeline connected to the liquid storage chamber should preferably be connected to the upper part of the liquid storage chamber. A controllable on-off first solenoid valve is set on the pipeline connecting the vacuum pump and the liquid storage chamber, and a controllable on-off second solenoid valve is set on the pipeline connecting the vacuum pump and the detection chamber. Then connect the detection chamber and the liquid storage chamber with a liquid suction pipe, and set a fourth electromagnetic valve that can control on-off on the liquid suction pipe;

c. The operator steps on the brake pedal repeatedly to make the air mixed in the brake fluid of the brake circuit gradually gather at the installation hole of the air release screw of the brake circuit, and then continues to step on the brake pedal to make the pressure of the brake circuit Gradually rise, at this time, the first hydraulic sensor arranged on the exhaust pipe between the third solenoid valve and the connecting head outputs a pressure signal to the control device;

d. When the pressure of the brake circuit is greater than or equal to 3 MPa, the control device opens the second solenoid valve and the vacuum pump, and the vacuum pump vacuumizes the detection chamber in the detection cylinder, and then closes the second solenoid valve to keep the detection chamber Vacuum state. Of course, we can install a corresponding vacuum sensor on the detection chamber to output the vacuum degree signal of the detection chamber, so that the control device can accurately and automatically control the closing of the second solenoid valve;

e. The control device opens the third solenoid valve, and depending on the pressure difference between the brake circuit and the detection chamber, the air mixed with brake fluid in the brake circuit enters the detection chamber through the exhaust pipe until it fills the entire detection chamber. Since the air mixed with brake fluid fills the entire detection chamber, the pressure of the detection chamber is consistent with the pressure of the brake circuit. Therefore, at this time, the second hydraulic sensor installed on the detection cylinder can output a The pressure signal in the detection chamber, when the pressure signal is equal to the pressure signal of the first hydraulic sensor, the control device can determine that the air mixed with brake fluid is full of the entire detection chamber;

f. The control device closes the third solenoid valve so that the detection chamber forms a closed cavity, and then starts a driving device to push the pressurized plunger at one end of the detection chamber to move, so that the detection chamber is mixed with brake fluid The pressure of the air gradually rises, and the hydraulic pressure sensor arranged on the detection cylinder outputs the pressure signal in the detection chamber to the control device. In order to facilitate the control of the movement of the pressurized plunger, the driving device includes a motor 5 that is electrically connected to the control device. The motor can preferably be a stepper motor, and the output shaft of the motor is coaxially connected to a drive screw 51. The end of the plunger away from the exhaust pipe is connected with an outer sleeve 52, and the outer sleeve extends outwards from the end of the detection cylinder, and the driving screw is threadedly connected in the outer sleeve. In this way, when the motor drives the driving screw to rotate, it can drive the outer casing threaded with it to move reciprocally in the axial direction, and then drive the pressurizing plunger to move. It should be noted that an axial limiting groove 521 may be provided on the outer wall of the outer casing, and correspondingly, the end of the detection cylinder is provided with a limiting protrusion 33 that is locked in the limiting groove to prevent the outer casing from The tube rotates with the drive screw;

g. When the driving device drives the pressurized plunger to move in place, the control device records the highest pressure signal value P in the detection chamber, and then the control device opens the fourth solenoid valve and the first solenoid valve, and the vacuum pump forms a negative pressure in the liquid storage chamber. Pressure, so that a pressure difference is formed between the negative pressure liquid storage chamber and the high pressure detection chamber, and the brake fluid in the detection chamber flows into the liquid storage chamber through the suction pipe. In order to prevent the brake fluid in the liquid storage chamber from being sucked away by the vacuum pump, we can vertically set a liquid return pipe 21 extending into the bottom of the liquid storage chamber on the top of the liquid storage chamber, and one end of the suction pipe is connected to the detection cylinder. body away from the end of the pressurized plunger, the other end of the suction pipe is connected to the upper end of the liquid return pipe, while the suction pipe is connected to the side wall of the detection cylinder, and the pipeline connected to the vacuum pump is connected to the upper part of the liquid storage chamber . In this way, when the vacuum pump works and communicates with the liquid storage chamber, the air in the upper part of the liquid storage chamber is drawn out to form a negative pressure, and the brake fluid in the detection chamber enters the bottom of the liquid storage chamber together with the air, and the air in it forms bubbles and gradually It rises and is released into the upper space of the liquid storage chamber, while the brake fluid is stored in the lower part of the liquid storage chamber, thereby achieving good gas-liquid separation.

h. The control device compares the highest pressure signal value P with the pre-stored set value P ₀ and makes a judgment. If P is greater than or equal to P ₀ at this time, the exhaust procedure will end; if this P is less than P ₀ , repeat Step c to step g.

It should be noted that the set value P ₀ can be obtained through experiments. Specifically, we can first set up a detection chamber with a suitable volume, and draw the air mixed with brake fluid in the brake circuit into the detection chamber. Through manual observation, it is ensured that only the brake fluid is extracted at the end, that is to say, this The air in the brake circuit has been expelled. If not all the brake fluid is pumped out at this time, then move the pressurizing plunger accordingly to increase the volume of the detection chamber, and then continue pumping until only the brake fluid position is manually observed. Then continue to move the pressurizing plunger for a certain distance, thereby setting the standard volume of the detection chamber, so that one pumping of the detection chamber can ensure that all the gas in the brake circuit is completely discharged. Then inject compressed air into the detection cavity of standard volume until the pressure in the detection cavity is equal to the pressure of the brake circuit. At this time, the pressurizing plunger is moved a fixed distance to gradually increase the pressure in the detection chamber, and the hydraulic sensor can output a maximum pressure signal value. When we repeat the above test on the brake circuits of multiple electric vehicles, we can obtain multiple highest pressure signal values, and the smallest one of the highest pressure signal values can be used as the set value P ₀ of the present invention. In this way, when the pressure plunger moves the same fixed distance, as long as the highest pressure signal value P of the detection chamber is greater than or equal to the set value P ₀ , it can ensure that the air in the brake circuit is completely discharged.

In addition, in order to ensure that the brake fluid in the detection chamber is completely pumped into the liquid storage chamber, we can set a position sensor on the detection cylinder to detect the position of the pressurized plunger. A position sensor is arranged at the end, and a corresponding trigger block is arranged on the outer sleeve protruding from the detection cylinder. In this way, the following steps can be added in step g: the control device moves the pressurized plunger to the end of the detection chamber close to the suction pipe through the driving device, so that the brake fluid mixed with air in the detection chamber flows into the liquid storage chamber, At this time, the trigger block triggers the position sensor, and the position sensor can output a position signal to the control device, and the control device makes the motor of the driving device reversely rotate, so that the pressurizing plunger can be reversely moved and reset.

Claims (3)

1. a kind of method for exhausting of braking system of electric car, it is characterized in that, include the following steps：

A. it is connected with one end of the exhaust tube equipped with the 3rd solenoid valve with a detection cylinder body with test chamber, exhaust tube The connector of the other end is connected with the bleed screw mounting hole of braking system；

B. the bleeding point of a vacuum pump and the test chamber of detection cylinder body and the liquid storage that brake fluid can be stored are connected with pipeline Chamber, and the first solenoid valve is set on the pipeline of connection vacuum pump and liquid storage cylinder, on connection vacuum pump and the pipeline of test chamber Second solenoid valve is set, with liquid suction pipe connecting detection chamber and liquid storage cylinder, and the 4th solenoid valve is set on liquid suction pipe；

C. brake pedal is first trampled repeatedly, the air in brake circuit is gathered at the bleed screw mounting hole of brake circuit, Then be continuously stepping on brake pedal, be gradually increasing the pressure of brake circuit, be arranged at this time the 3rd solenoid valve and connector it Between exhaust tube on hydrostatic sensor to control device export a signal；

D. when the pressure of brake circuit is more than or equal to 3 megapascal, control device opens second solenoid valve, and opens vacuum pump, will Test chamber in detection cylinder body vacuumizes, and then turns off second solenoid valve；

E. control device opens the 3rd solenoid valve, and the air that brake fluid is mixed with brake circuit is entered by exhaust tube In test chamber；

F. control device closes the 3rd solenoid valve, then starts a driving device, to promote the pressurization of one end in test chamber Plunger moves, so that the pressure that the air of brake fluid is mixed with test chamber is gradually increasing, the liquid being arranged on detection cylinder body Pressure sensor then exports the pressure signal in test chamber to control device；

G. when driving device drives pressure plunger to be moved into place, the maximum pressure signal value in control device record test chamber P, then control device open the 4th solenoid valve and the first solenoid valve, vacuum pump makes to form negative pressure in liquid storage cylinder, so that negative Form pressure differential between the liquid storage cylinder of pressure and the test chamber of high pressure, the brake fluid in test chamber flows into liquid storage cylinder by liquid suction pipe It is interior；

H. control device is by the maximum pressure signal value P and setting value P that prestores₀It is compared and judges, if this When P be more than or equal to P₀, then vent sequence is terminated；If this P is less than P₀, then repeat step c to step g.

2. a kind of method for exhausting of braking system of electric car according to claim 3, it is characterized in that, the driving device Including the outer tube being connected with pressure plunger, driving screw rod is connected with outer tube internal thread, the driving screw rod stretches out outer One end of casing and the output shaft of motor are coaxially connected, and the motor is electrically connected with control device, the lateral wall of the outer tube Axial limit card slot is equipped with, the end of the detection cylinder body is equipped with limit protrusion of the screens in limit card slot, it is necessary to open During dynamic driving device, control device starts motor, and motor drives drive screw turns, so as to drive the overcoat being threadedly coupled with it Pipe moves axially, and then drives pressure plunger to be moved in test chamber.

3. a kind of method for exhausting of braking system of electric car according to claim 1, it is characterized in that, on the top of liquid storage cylinder Portion is vertically equipped with the liquid back pipe for stretching into liquid storage cylinder bottom, and one end of the liquid suction pipe is connected to detection cylinder body away from pressure plunger One end, the other end of liquid suction pipe are connected with the upper end of liquid back pipe, and the exhaust tube is connected on the side wall of detection cylinder body, is being examined Survey cylinder body and be equipped with the position sensor for being used for detecting pressure plunger position, and increase step is as follows in step g：Control dress Put makes pressure plunger be moved in test chamber close to liquid suction pipe one end by driving device, makes the system that air is mixed with test chamber Hydrodynamic is flowed into liquid storage cylinder, and position sensor exports a position signal to control device at this time, and control device is filled by driving Putting resets pressure plunger reverse movement.