CN107738638B

CN107738638B - Composite braking system with line control function

Info

Publication number: CN107738638B
Application number: CN201710840910.4A
Authority: CN
Inventors: 陈燎; 盘朝奉; 孙登辉; 戴伟; 陈龙; 江浩斌; 徐兴; 孙晓东; 李勇
Original assignee: Jiangsu University
Current assignee: Shandong Zhongli Auto Parts Manufacturing Co ltd
Priority date: 2017-09-18
Filing date: 2017-09-18
Publication date: 2020-03-31
Anticipated expiration: 2037-09-18
Also published as: CN107738638A

Abstract

The invention discloses a compound braking system with a brake-by-wire function, belonging to the technical field of automobile braking, comprising a brake pedal, a brake booster, a brake master cylinder, a two-position five-way slide valve, a stroke simulator, Hydraulic adjustment module (motor, oil pump, high pressure accumulator, 2/2 solenoid valve, hydraulic adjustment cylinder), pedal displacement sensor, pressure sensor and brake controller. It is characterized in that it integrates two independent hydraulic control mechanisms, which are switched through a two-position five-way spool valve. Under normal circumstances, a hydraulic brake-by-wire system (EHB) is generated through a motor, a pump, a solenoid valve and a hydraulic adjustment cylinder. When the system fails, the traditional mechanical braking system is used; a displacement sensor is installed at the brake pedal to determine the size of the total braking force; pressure sensors are installed in the front and rear wheel pipelines to ensure real-time control of the hydraulic adjustment module; the pedal is used for normal braking The force is fed back by the travel simulator, which realizes the mechanical decoupling of the braking system.

Description

Composite braking system with line control function

Technical Field

The invention belongs to the technical field of automobile braking, and particularly relates to a composite braking system of an electric automobile with a brake-by-wire braking function.

Background

At present, the development of an electric automobile taking electricity as a power source is an effective way for relieving the problems of energy shortage and environmental pollution, and the electric automobile is characterized in that: in the braking process, kinetic energy of the vehicle is converted into electric energy through the motor, the electric energy is stored in an energy storage device such as a storage battery and a super capacitor, and braking torque is generated at the same time. However, the braking torque generated by the motor cannot meet the requirements of different braking conditions, and the electric braking torque can change along with the vehicle speed and the battery SOC, so that the common electric vehicle keeps a transmission hydraulic braking system. How to coordinate and control the two braking torques has important significance for ensuring driving safety and improving the energy recovery rate of the electric automobile, and changing the structure of the traditional braking system is a fundamental method for solving the problem of composite braking. The ideal distribution mode of the two braking torques in the braking process is shown in fig. 2, which requires that the composite braking system can adjust the magnitude of the hydraulic pressure in real time.

The patents having a large relevance to the present invention are as follows

The patent CN200910243332.1 of Qinghua university discloses a compound brake system, which realizes the decoupling of pedal force and brake fluid pressure through a three-way valve, and connects two-position two-way electromagnetic valves in front of an ABS/ESP to realize hydraulic regulation. The disadvantages of this system are: 1. hydraulic pressure directly flows from the oil storage tank to the wheel cylinder through the electromagnetic valve of the energy accumulator without a buffering pressure adjusting cylinder, so that the oil pressure change is quick, the switching frequency of the corresponding control electromagnetic valve is higher, and the control precision is not high; 2. there is no effective failure backup mode, the electromagnetic valve is easy to fail under the high-speed switch, once hydraulic pressure can not be established, there is a great hidden trouble in driving safety.

Second, the patent CN201310576356.5 of taibo electronic intelligent technology ltd, Yangzhou also integrates two sets of brake systems, and the wire control system adopts a motor as a power source, and adopts an electromagnetic valve for controlling the mode switching with the traditional hydraulic system. The disadvantages of this system are: 1. the hydraulic braking force of the front axle and the rear axle can only be adjusted, and the hydraulic braking force of the front axle and the rear axle can not be accurately distributed, which has great influence on the electric automobile driven by the single axle; 2. there is also a braking safety issue with electrical control failures.

Disclosure of Invention

In order to solve the above problems, an object of the present invention is to provide an accurate and effective hydraulic pressure regulating system, which realizes the coordinated distribution of electric braking torque and hydraulic braking torque of an electric vehicle, provides good pedal feel, and ensures that a traditional mechanical structure can intervene in a braking system in due time under the condition of failure of an electric control system, thereby ensuring the braking safety of the vehicle.

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

a composite braking system with a line control function comprises a brake pedal, a brake booster, a brake master cylinder, a two-position five-way sliding valve, a stroke simulator, a hydraulic adjusting module (a motor, an oil pump, a high-pressure energy accumulator, a two-position two-way electromagnetic valve and a hydraulic adjusting cylinder), a pedal displacement sensor, a pressure sensor and a brake controller. The hydraulic brake system is characterized in that two sets of brake hydraulic control systems are integrated, wherein one system is a traditional brake system which generates hydraulic pressure through a mechanical structure according to pedal force; the brake-by-wire system is characterized in that a motor and a pump are used as power sources, different hydraulic pressures are controlled through a solenoid valve switch, and the traditional brake system is used as a failure backup mode of the brake-by-wire system to ensure the brake safety. The switching and interlocking of the two brake systems are realized through a two-position five-way sliding valve, a push rod of a valve core of the two brake systems is coupled with a push rod of a piston of a hydraulic adjusting cylinder, and meanwhile, a stroke simulator is timely connected into the two brake systems according to the position of the valve core, so that good pedal feeling is provided.

The switching mechanism is a two-position five-way sliding valve, the valve core has two positions, and when the valve core is in one position, a channel is formed between a master cylinder and a wheel cylinder of the traditional braking system, and an oil return channel of the brake-by-wire system is closed; in position two, the path between the master cylinder of the conventional brake system and the stroke simulator and the path of the brake-by-wire system return path. Different and active control, the traditional brake system can intervene in real time to ensure the driving safety when the brake-by-wire can not build pressure through a mechanical structure.

The number of the hydraulic adjusting cylinders is 2, and the hydraulic pressure of the brake of the front shaft and the brake of the rear shaft are respectively and independently adjusted; each cylinder body is divided into 3 chambers, a first piston and a second piston; the first cavity is a power generation cavity, and the hydraulic pressure of the first cavity pushes the piston to generate braking hydraulic pressure in the second cavity and the third cavity to the brake wheel cylinder; the second and third hydraulic chambers are at the same pressure but are independent.

The first cavity pressure of the hydraulic adjusting cylinder generates power from a high-pressure energy accumulator, the system converts low-pressure oil in the oil storage tank into high-pressure oil through a motor and an oil pump and stores the high-pressure oil in the high-pressure energy accumulator, and the first cavities of the two adjusting cylinders share one set of power source.

The pressure of the first cavity of the hydraulic adjusting cylinder is adjusted through high-speed switches of the two-position two-way electromagnetic valves, and in order to achieve the difference of two paths of hydraulic pressure, each hydraulic adjusting cylinder is respectively provided with two electromagnetic valves.

And the second and third chambers of the hydraulic adjusting cylinder are pressurized to have certain idle strokes for switching the positions of the two-position five-way valve.

The two-position five-way slide valve is provided with a return spring K1, and the hydraulic adjusting cylinder is provided with return springs K2 and K3. K1-K3 are in a compressed state all the time, when the valve core and the piston are in the first position, the elastic force generated by K1 is F1, the elastic force generated by K2 and K3 is F2, and F2> F1. The valve core push rod of the two-position five-way slide valve is coupled with the piston of the hydraulic adjusting cylinder, and the valve core push rod is not mechanically connected with the valve core. When the first chamber of the hydraulic adjusting cylinder has no pressure, the two-position five-way sliding valve is in the first position under the action of spring force, namely, the traditional mechanical brake system can play a role when the brake-by-wire system cannot build pressure. When the pressure in the first chamber of the hydraulic adjusting cylinder is built up, the two-position five-way slide valve is in the second position under the action of K1, meanwhile, the stroke simulator is connected with feedback brake feeling, and the brake-by-wire system provides hydraulic pressure.

The invention has the beneficial effects that:

1. the invention overcomes the defects of the existing composite braking system, can realize the flexible adjustment (from 0 to the highest) of the hydraulic braking force of the front axle and the rear axle, and ensures that the hydraulic braking system and the motor braking system can work coordinately;

2. in the process of composite braking, the pedal feels consistent and stable, the stroke marks the total braking torque, the change of the hydraulic pressure cannot be fed back to the pedal, and the driving habit of a driver is compounded.

3. The hydraulic pressure adjusting mode is a combination of normally open and normally closed valves, and the buffering effect of the hydraulic pressure adjusting cylinder is added, so that the hydraulic pressure change is slowed down, and the adjusting precision is improved.

4. The two-position five-way sliding valve effectively designs a set of failure protection mode of the brake-by-wire system through a mechanical structure, and ensures the braking safety of the vehicle.

Drawings

FIG. 1 is a structural view of a composite brake system with a brake-by-wire function according to the present invention

FIG. 2 is a torque distribution diagram of electric braking and hydraulic braking in a combined braking process

Detailed Description

The invention is described in further detail below with reference to the figures and the embodiments.

As shown in fig. 1, the composite brake system with a line control function comprises a brake pedal 1, a brake booster 2, a brake master cylinder 3, a two-position five-way slide valve a11, a two-position five-way slide valve b12, a stroke simulator a15, a stroke simulator b16, a hydraulic pressure adjusting module (a motor 5, an oil pump, a high pressure accumulator 6, a two-position two-way solenoid valve a7, a two-position two-way solenoid valve b8, a two-position two-way solenoid valve c9, a two-position two-way solenoid valve d10, a hydraulic pressure adjusting cylinder a13, a hydraulic pressure adjusting cylinder b14), a pedal displacement sensor 17, a pressure sensor a18, a pressure sensor b19 and a brake controller 20.

The structure integrates two sets of brake hydraulic control systems. One is a conventional brake system that generates hydraulic pressure through a mechanical structure according to pedal force: brake fluid of the brake cylinder is transmitted to a brake wheel cylinder by a master cylinder 3 through pipelines I1 and I2 through a BP passage of a two-position five-way slide valve a11 and a two-position five-way slide valve b 12; the second is a brake-by-wire system which takes the motor 5 and the pump 4 as power sources and controls different hydraulic pressures through the switch of an electromagnetic valve a7, an electromagnetic valve b8, an electromagnetic valve c9 and an electromagnetic valve d 10: the brake fluid is transmitted from the oil storage tank 22 to the hydraulic pressure adjusting cylinder a13 and the hydraulic pressure adjusting cylinder b14, and then to the brake wheel cylinder through pipelines II1 and II 2. The traditional brake system is used as a failure backup mode of the brake-by-wire system, and the brake safety is ensured. The switching and interlocking of the two brake systems are realized through a two-position five-way sliding valve a11 and a two-position five-way sliding valve b12, a push rod of a valve core of the two brake systems is coupled with a piston push rod of a hydraulic adjusting cylinder, and a stroke simulator a1 and a stroke simulator b16 are timely switched into the two brake systems according to the position of the valve core, so that good pedal feeling is provided.

The operation of the structure will be described in connection with the braking process of the vehicle.

When not braking, the initial state. The displacement of the brake pedal 1 is 0, and the valve cores of the two-position five-way slide valve a11 and the two-position five-way slide valve b12 and the pistons of the hydraulic adjusting cylinder a13 and the hydraulic adjusting cylinder b14 are in a first position (the leftmost end), namely a BP port passage, under the action of springs K2 and K3; the stroke simulator a15 and the stroke simulator b16 are disconnected, namely BT is disconnected; the second and third chambers of the hydraulic adjusting cylinder a13 and the hydraulic adjusting cylinder b14 are disconnected from the oil storage tank 22, namely the AQ circuit breaker; the two-position two-way electromagnetic valve a7, the two-position two-way electromagnetic valve c9 are normally closed valves, the two-position two-way electromagnetic valve b8 and the two-position two-way electromagnetic valve d10 are normally open valves, the motor 5 and the pump 4 do not work, at this time, the first chambers of the hydraulic adjusting cylinder a13 and the hydraulic adjusting cylinder b14 are communicated with the oil storage tank 22, namely, the first chambers have no hydraulic pressure.

Braking begins. The brake controller 20 receives the signal of the pedal displacement sensor 17, outputs a control signal after judging that the brake state is the brake state, so that the motor 5 and the pump 4 work, the electromagnetic valve a7 and the electromagnetic valve c9 are opened, and the electromagnetic valve b8 and the electromagnetic valve d10 are closed; the hydraulic pressure generated by the first chamber of the hydraulic adjusting cylinder a13 and the hydraulic adjusting cylinder b14 pushes the piston to move rightwards until the oil inlets of the second chamber and the third chamber are closed, and the electromagnetic valve a7 and the electromagnetic valve c9 are closed after the pressure sensor a18 and the pressure sensor b19 judge that the wheel cylinder builds up smaller pressure. At the moment, the valve cores of the two-position five-way sliding valve a11 and the two-position five-way sliding valve b12 are separated from the piston push rod, the valve cores are placed at the second position (the rightmost end) under the action of a spring K1, the sliding valve BP is disconnected, and the traditional brake pipeline is closed; a BT passage, a stroke simulator is connected into a master cylinder 3 of the pedal 1 to provide braking feeling feedback; the AQ passages allow the second and third chambers of the hydraulic cylinder a13 and the hydraulic cylinder b14 to be in communication with the reservoir 22, allowing both chambers to be depressurized.

And (5) increasing and reducing the pressure. The brake controller 20 obtains the required total braking torque through the pedal displacement sensor 17, obtains the torque provided by the electric braking energy after exchanging information with the vehicle controller, and distributes the hydraulic braking force required by the front axle and the rear axle in real time through calculation. The hydraulic pressure sensors a18 and b19 monitor the front and rear shaft hydraulic pressure in real time, the electromagnetic valves a7 and c9 are opened during pressurization, the electromagnetic valves b8 and d10 are closed, the electromagnetic valves a7 and c9 are closed during decompression, the electromagnetic valves b8 and d10 are opened, and the electromagnetic valves a7, b8, c9 and d10 are closed within certain precision to realize pressure maintaining. High-pressure oil is generated by a motor 5 and a pump 4 and is stored in a high-pressure energy accumulator 6, and low-pressure oil is oil in a liquid storage tank 22.

The by-wire system fails. The first failure mode is that the first chambers of the hydraulic adjusting cylinder a13 and the hydraulic adjusting cylinder b14 cannot build pressure, and the reason is that the power supply of the motor fails; motor or pump failure; solenoid a7, solenoid c9 did not close normally. At the moment, the original state is returned, the valve core of the two-position five-way slide valve a11 and the two-position five-way slide valve b12 and the piston of the hydraulic adjusting cylinder a13 and the hydraulic adjusting cylinder b14 are in the first position under the action of the springs K2 and K3, and the traditional hydraulic brake system is restored to the function. The failure mode hydraulic pressure adjusting cylinder a13 and the hydraulic pressure adjusting cylinder b14 cannot reduce pressure, the electromagnetic valve b8 and the electromagnetic valve d10 are not normally closed, hydraulic pressure exists in a brake pipeline at the moment, the brake pipeline cannot be adjusted, the brake force of the vehicle is guaranteed, and safe braking can be achieved.

The ABS operates. In the system, two sets of system pressure regulation can work with anti-lock braking system 21 coordinately, and ABS regulates pressure independently according to wheel speed sensor under the condition of high braking intensity or emergency braking.

In the description herein, references to the description of the term "one embodiment," "some embodiments," "an illustrative embodiment," "an example," "a specific example," or "some examples" or the like mean that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the invention. In this specification, the schematic representations of the terms used above do not necessarily refer to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

While embodiments of the invention have been shown and described, it will be understood by those of ordinary skill in the art that: various changes, modifications, substitutions and alterations can be made to the embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the claims and their equivalents.

Claims

1. A compound braking system with a brake-by-wire function, characterized in that it comprises a brake pedal (1), a brake booster (2), a master cylinder (3), a two-position five-way spool valve a (11) ), 5/2 spool valve b (12), stroke simulator a (15), stroke simulator b (16), pedal displacement sensor (17), pressure sensor a (18), pressure sensor b (19), A brake controller (20) and a hydraulic adjustment module; the hydraulic adjustment module includes a motor (5), an oil pump (4), a high-pressure accumulator (6), a two-position two-way electromagnetic valve a (7), a two-position two-way electromagnetic valve Valve b (8), two-position two-way solenoid valve c (9), two-position two-way solenoid valve d (10), hydraulic adjustment cylinder a (13), hydraulic adjustment cylinder b (14);

The oil storage tank (22) has four pipelines, two of which are connected to the front and rear chambers of the master cylinder (3), and the front and rear chambers of the master cylinder (3) are connected to the 5/2-way slide valve a (11), the 5/2-way valve Spool valve b(12) B port, 5/2-way spool valve a(11), 5/2-way spool valve b(12) P port is connected to ABS(21) oil inlet, ABS(21) and four wheel cylinders The pipelines of the front and rear wheels are each equipped with a pressure sensor a (18) and a pressure sensor b (19). The solenoid valve a(7) and solenoid valve c(9) are connected to the first chamber of the hydraulic adjustment cylinder a(13) and the hydraulic adjustment cylinder b(14); ), two-position five-way spool valve b(12) A port, and connect the second and third chambers of hydraulic adjustment cylinder a(13) and hydraulic adjustment cylinder b(14) through its Q port. A solenoid valve b(8) and solenoid valve are installed between the valve a(11), the 5/2 spool valve b(12) and the first chamber of the hydraulic adjustment cylinder a(13) and the hydraulic adjustment cylinder b(14). d(10); 5/2-way spool valve a(11), 5/2-way spool valve b(12) T ports are respectively connected to stroke simulator a(15) and stroke simulator b(16); 5/2-way spool valve b(12) The slide valve a (11) and the two-position five-way slide valve b (12) are connected with the hydraulic adjustment cylinder a (13) and the hydraulic adjustment cylinder b (14) through a push rod;

The system structure integrates two sets of brake hydraulic control systems:

The first set is a traditional brake system that generates hydraulic pressure through a mechanical structure according to the pedal force: the brake fluid is passed from the master cylinder (3) through the pipeline I1 and pipeline I2 through the two-position five-way spool valve a (11), the two-position spool valve a (11), the two-position The BP passage of the five-way spool valve b (12) is connected to the brake wheel cylinder;

The second set uses the motor (5) and the oil pump (4) as the power source, and controls different hydraulic pressures by switching the solenoid valve a (7), solenoid valve b (8), solenoid valve c (9), and solenoid valve d (10). Brake-by-wire system of force: the brake fluid is transferred from the oil storage tank (22) to the hydraulic adjustment cylinder a (13), the hydraulic adjustment cylinder b (14), and through the pipelines II1 and II2 to the brake wheel cylinder;

The traditional braking system is used as the fail-back mode of the brake-by-wire system; the switching and interlocking of the two braking systems are realized by the two-position five-way slide valve a (11) and the two-position five-way slide valve b (12), The push rod of the valve core is coupled with the piston push rod of the hydraulic adjustment cylinder, and at the same time according to the position of the valve core, the stroke simulator a (15) and the stroke simulator b (16) are connected to the system to provide a good pedal feel.

2. A compound braking system with a brake-by-wire function according to claim 1, characterized in that: the two-position five-way spool valve a (11), the two-position five-way The spool has two positions. In position 1, the passage between the master cylinder and the wheel cylinder of the traditional brake system and the return oil circuit of the brake-by-wire system is closed; in position 2, between the master cylinder of the traditional brake system and the stroke simulator access and the brake-by-wire system return oil path.

3. A compound braking system with a brake-by-wire function according to claim 2, characterized in that: in the hydraulic adjustment cylinder a (13) and the hydraulic adjustment cylinder b (14), each cylinder is divided into There are 3 chambers, the first chamber is the power generation chamber, and the second and third chambers are the brake hydraulic pressure generation chambers.

4. A compound brake system with a brake-by-wire function according to claim 3, wherein the hydraulic adjustment cylinder a (13) and the hydraulic adjustment cylinder b (14) independently adjust the brake hydraulic pressure of the front and rear axles respectively. The hydraulic pressure from each pressure regulating cylinder to the coaxial wheel cylinder is equal but independent.

5. A compound brake system with brake-by-wire function according to claim 3, characterized in that: the first chamber of the hydraulic adjustment cylinder a (13) and the hydraulic adjustment cylinder b (14) share a set of the first chamber driven by the motor (5), a power source composed of an oil pump (4) and a high-pressure accumulator (6).

6. A compound brake system with a brake-by-wire function according to claim 3, wherein the pressures of the first chambers of the hydraulic adjustment cylinder a (13) and the hydraulic adjustment cylinder b (14) are respectively determined by The switch of the solenoid valve is independently adjusted.

7. A compound braking system with a brake-by-wire function according to claim 2 or 3, wherein the two-position five-way slide valve a (11) and the two-position five-way slide valve b (12) are both There is a return spring K1; the hydraulic adjustment cylinder a (13) and the hydraulic adjustment cylinder b (14) have return springs K2 and K3. K1 to K3 are always in a compressed state. When the valve core and the piston are in position one, the elastic force generated by K1 is F1, The elastic force generated by K2 and K3 is F2, and F2>F1.

8. A compound braking system with brake-by-wire function according to claim 2 or 3, characterized in that: The valve core push rod is coupled with the pistons of the hydraulic adjustment cylinder a (13) and the hydraulic adjustment cylinder b (14), and there is no mechanical connection between the valve core push rod and the valve core; when the hydraulic adjustment cylinder a (13), the hydraulic adjustment cylinder When the first chamber of the cylinder b (14) has no pressure, under the action of the spring force, the 5/2-way spool valve a (11) and the 5/2-way spool valve b (12) are in position one, that is, when the brake-by-wire system When the pressure cannot be built up, the traditional mechanical brake system can play a role; when the pressure is established in the first chamber of the hydraulic adjustment cylinder a (13) and the hydraulic adjustment cylinder b (14), the two-position five-way spool valve a (11), the second chamber The 5-way spool valve b (12) is in position 2 under the action of K1, and the travel simulator is connected to feedback braking feeling, and the brake-by-wire system provides hydraulic pressure.