Redundant brake system based on tandem double cavity caliper and its application

Abstract

The application relates to a redundant braking system with power-off self-braking, a control method and application thereof, and a redundant braking system based on a series double-cavity caliper, comprising a pump, an accumulator, a normally-open valve, a normally-closed valve and a brake wheel cylinder; an oil outlet of the pump is communicated with the accumulator, an oil inlet of the brake wheel cylinder is communicated with an oil outlet of the accumulator and a brake master cylinder of a vehicle system; the normally-open valve is connected between the accumulator and the brake wheel cylinder, and the normally-closed valve is connected between the brake master cylinder and the brake wheel cylinder; the normally-open valve and the normally-closed valve are powered by a power supply of the vehicle system. The technical scheme can meet the technical requirement that the braking function is still available when the power supply fails.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of autonomous driving vehicles, in particular to a redundant braking system based on a tandem double-cavity caliper and application thereof. BACKGROUND

[0002] Redundancy of the braking system is an important feature of autonomous driving vehicles, which prevents the vehicle from running in danger when one of the braking systems is damaged. In patent application CN202311024440.6, a redundant braking system is proposed, which switches the braking source through a double-pass one-way valve (shuttle valve), and an electric proportional valve is used as redundancy. When the electric proportional valve is powered on, it outputs a certain pressure, and the double-pass one-way valve outputs the larger one of the electric proportional valve and the angular valve communication port. This means that when the angular valve is damaged, braking can still be achieved by controlling the proportional valve, i.e. the braking redundancy function is realized. However, once the vehicle is powered off, the proportional electric valve will also fail, and the vehicle will also lose braking, so in some systems with high redundancy requirements (such as high-speed rail, subway), it cannot meet the requirement that the braking function is still available when the power supply fails. Therefore, the present application proposes a redundant braking system with active braking when the power is off to solve this problem. SUMMARY

[0003] Therefore, the present application proposes a redundant braking system with active braking when the power is off to solve this problem.

[0004] In order to achieve the above object, the application adopts the following technical scheme: a redundant braking system based on series double-cavity calipers is applied to a redundant braking assembly for power-off self-braking, comprising a double-cavity caliper, wherein the double-cavity caliper comprises a piston cavity and a movable cavity; the piston cavity is communicated with the movable cavity, the piston cavity is provided with a first piston and a second piston which are independent of each other, and the first piston and the second piston are provided with elastic elements in the middle; one end of the first piston away from the second piston is arranged close to the right cavity bottom of the piston cavity, and the right cavity bottom of the piston cavity is provided with a first connecting port communicated with a first oil inlet; the lower bottom of the piston cavity between the first piston and the second piston is provided with a second connecting port communicated with a second oil inlet; the left opening of the piston cavity is communicated with the movable cavity, one side of the second piston away from the first piston is provided with a first friction plate, and one side of the movable cavity facing the second piston is provided with a second friction plate; the redundant braking assembly for power-off self-braking comprises a pump, an accumulator, a normally open valve, a normally closed valve and a brake cylinder; the oil outlet of the pump is communicated with the accumulator, the oil inlet of the brake cylinder is communicated with the oil outlet of the accumulator and a brake master cylinder of a vehicle system; the accumulator and the brake cylinder are connected with the normally open valve, and the brake master cylinder and the brake cylinder are connected with the normally closed valve; the normally open valve and the normally closed valve are powered by a power supply of the vehicle system.

[0005] In a preferred embodiment, the control method of the redundant braking assembly for power-off self-braking comprises:

[0006] 1) normal braking: the normally open valve and the normally closed valve are powered on, if the brake pedal is stepped down at this time, high-pressure oil generated by the brake pedal enters the brake cylinder to form braking, when the brake pedal is released, the oil returns to the brake master cylinder to remove the braking; at this time, the ECU simultaneously judges whether the pressure of the accumulator is sufficient, if the pressure is insufficient, the pump is controlled to work to increase the pressure in the accumulator;

[0007] 2) redundant braking application: at this time, the normally open valve and the normally closed valve are powered off, and high-pressure oil in the accumulator enters the brake cylinder;

[0008] 3) redundant braking removal: when the vehicle system is restored to normal, the normally closed valve is powered on, at this time, high-pressure oil flows to the brake master cylinder through the normally closed valve, and then flows to the main oil pot.

[0009] The application also provides a redundant braking system based on a series double-cavity caliper, which is applied to a power-off self-braking redundant braking assembly, comprising a double-cavity caliper, wherein the double-cavity caliper comprises a piston cavity and a movable cavity; the piston cavity is communicated with the movable cavity; a first piston and a second piston which are independent of each other are arranged in the piston cavity; the first piston and the second piston are provided with elastic elements in the middle; one end of the first piston away from the second piston is arranged close to the right cavity bottom of the piston cavity; the right cavity bottom of the piston cavity is provided with a first connecting port communicated with a first oil inlet; the lower bottom of the piston cavity between the first piston and the second piston is provided with a second connecting port communicated with a second oil inlet; the left opening of the piston cavity is communicated with the movable cavity; the second piston is provided with a first friction plate at one end away from the first piston; the movable cavity is provided with a second friction plate on the side facing the second piston; the power-off self-braking redundant braking assembly comprises a pump, an accumulator, a normally open valve, a normally closed valve, a normally closed leakage valve, a secondary oil pot and a brake cylinder; the oil outlet of the pump is communicated with the accumulator; the oil inlet of the brake cylinder is communicated with the oil outlet of the accumulator and a brake master cylinder of a vehicle system; the accumulator and the brake cylinder are connected with the normally open valve; the brake master cylinder and the brake cylinder are connected with the normally closed valve; the pump is connected with the secondary oil pot of the vehicle system; the brake cylinder is further communicated with the secondary oil pot before being connected with the normally open valve and the normally closed valve; the normally closed leakage valve is arranged between the brake cylinder and the secondary oil pot; the normally closed leakage valve, the normally open valve and the normally closed valve are powered by a power supply of the vehicle system.

[0010] In a preferred embodiment, the control method of the power-off self-braking redundant braking assembly comprises:

[0011] 1) Normal braking: the normally open valve and the normally closed valve are powered on; when the brake pedal is stepped on, the oil enters the brake cylinder for normal braking; at this time, if there is an unexpected pressure rise, the normally closed leakage valve is powered on to prevent the unexpected pressure rise;

[0012] 2) Redundant braking application: the normally closed leakage valve, the normally open valve and the normally closed valve are not powered on; the high-pressure oil in the accumulator enters the brake cylinder;

[0013] 3) Redundant braking removal: the normally closed leakage valve is powered on; the oil in the brake cylinder enters the secondary oil pot; the oil in the brake cylinder enters the front end of the pump through the normally closed leakage valve.

[0014] The application also provides a redundant brake system based on a series double-cavity caliper, which is applied to a power-off self-braking redundant brake assembly, comprising a double-cavity caliper, wherein the double-cavity caliper comprises a piston cavity and a movable cavity; the piston cavity is communicated with the movable cavity; a first piston and a second piston which are independent of each other are arranged in the piston cavity; the first piston and the second piston are provided with elastic elements in the middle; one end of the first piston away from the second piston is arranged close to the right cavity bottom of the piston cavity; the right cavity bottom of the piston cavity is provided with a first connecting port communicated with a first oil inlet; the lower bottom of the piston cavity between the first piston and the second piston is provided with a second connecting port communicated with a second oil inlet; the left opening of the piston cavity is communicated with the movable cavity; the second piston is provided with a first friction plate at one end away from the first piston; the movable cavity is provided with a second friction plate on the side facing the second piston; the power-off self-braking redundant brake assembly comprises a pump, an accumulator, a normally open valve, a normally closed leakage valve, a secondary oil pot and a brake wheel cylinder; the brake wheel cylinder is provided with a first oil inlet and a second oil inlet; the oil outlet of the pump is communicated with the accumulator; the first oil inlet of the brake wheel cylinder is communicated with the oil outlet of the accumulator; the second oil inlet of the brake wheel cylinder is communicated with a brake master cylinder of a vehicle system; the accumulator and the brake wheel cylinder are connected with the normally open valve; the pump is connected with the secondary oil pot of the vehicle system; the brake wheel cylinder is further communicated with the secondary oil pot before being connected with the normally open valve; the normally closed leakage valve is arranged between the brake wheel cylinder and the secondary oil pot; the normally closed leakage valve and the normally open valve are powered by a power supply of the vehicle system.

[0015] In a preferred embodiment, the control method of the power-off self-braking redundant brake assembly comprises:

[0016] 1) Normal braking: at this time, the normally open valve is powered on, and the normally closed leakage valve is powered off; when the brake pedal is stepped on, the oil enters the brake wheel cylinder through the second oil inlet for normal braking;

[0017] 2) Redundant brake application: at this time, the normally open valve is powered off, and the normally closed leakage valve is powered off; the oil in the accumulator enters the brake wheel cylinder for braking through the first oil inlet;

[0018] 3) Redundant brake removal: the normally closed leakage valve is powered on, and the oil in the brake wheel cylinder enters the secondary oil pot.

[0019] In a preferred embodiment, the oil in the first oil inlet is responsible for pushing the first piston to move left, the second oil inlet is responsible for pushing the second piston to move left, the first piston is close to the right limit of the caliper body in the normal state, that is, when the oil inlet of the first piston is not connected to oil, at this time the second oil inlet is not blocked by the first piston, the second piston is located at the left end of the second oil inlet in the normal state, that is, when the oil inlet of the second piston is not connected to oil, the first piston moves left under the action of oil, that is, blocks the second oil inlet, and when the first piston moves to the left end limit, the second oil inlet is still blocked.

[0020] In a preferred embodiment, the working principle is as follows:

[0021] The first case: the first oil inlet is connected to oil, then the first piston moves left, and further pushes the second piston to move left, and the first friction plate and the second friction plate gradually approach the clamped brake disc to realize braking, at this time if the first piston has blocked the second oil inlet, then the oil connected to the second oil inlet will not affect the state of the first piston and the second piston;

[0022] The second case: if the second piston is connected to oil, then the first piston is pushed to the right limit position, and the second piston is pushed to the left to generate braking; if the first oil inlet also applies oil at this time, if the pressure in the first oil inlet is greater than the pressure in the second oil inlet, then the first piston will be pushed to the left end, and then work according to the principle in the first case.

[0023] The application also provides an application of the redundant braking system based on the series double-cavity caliper, the redundant braking system based on the series double-cavity caliper, the redundant braking system is connected with the whole vehicle, wherein the electromagnetic valve control line of the vehicle system is connected with the electromagnetic valve of the redundant braking system, for controlling the electromagnetic valve, the whole vehicle CAN line is connected with the whole vehicle, for receiving information and instructions of the whole vehicle, and the emergency stop is used for controlling power supply of the redundant braking ECU;

[0024] The redundant braking system has the following modes:

[0025] Mode 1 is braking according to the emergency stop switch: when the emergency stop switch is pressed, the redundant braking ECU is powered off, at this time the normally open valve of the redundant braking system returns to the connected state, and the oil in the accumulator directly enters the brake wheel cylinder;

[0026] Mode 2 is emergency braking according to CAN heartbeat: it is judged that the main braking system fails, and enters the redundant braking mode;

[0027] Mode 3 is receiving CAN redundant braking instructions: if the main braking system sends fault information that the main braking is unavailable on the CAN, or sends redundant braking information, then the redundant braking ECU controls to enter the redundant braking mode;

[0028] Mode 4 is to collect CAN to judge deceleration request and actual deceleration: step 1) receiving the request a of the main brake system to request deceleration on CAN cmd , calculating the actual deceleration by vehicle speed , n represents the number of speed sampling points, derivative of the differential value of the speed v at the time point before the current time point i; step 2) calculating a danger degree index, the meaning of the index is that the greater the acceleration deviation or the longer the acceleration error lasts, the greater the danger degree, and the calculation method is J i =[J i-1 +f(-(a cmd -a r ))]*K, wherein J i is the danger degree index at the current time, J i-1 is the danger degree index at the last cycle, f(*) is a danger degree mapping function, and the meaning is that when a cmd -a r <0, the actual deceleration is greater than the expected deceleration, and at this time, the main brake system is normal, and the greater a cmd -a r >0 is, the greater the deceleration error is, that is, the main brake system is more likely to have a problem; 0 < K < 1, K is a decay coefficient, and is used to gradually reduce J to 0 after a period of time without danger; step 3) judging whether J i exceeds a preset threshold J Thre , and if it exceeds, it indicates that the danger degree is too large, and the redundant brake should be intervened.

[0029] Compared with the prior art, the application has the following beneficial effects: meeting the technical requirement of still having a brake function when the power supply fails. BRIEF DESCRIPTION OF DRAWINGS

[0030] Figure 1 is a power-off self-braking redundant brake assembly schematic diagram of preferred embodiment 1 of the application;

[0031] Figure 2 is a power-off self-braking redundant brake assembly schematic diagram of preferred embodiment 2 of the application;

[0032] Figure 3 is a power-off self-braking redundant brake assembly schematic diagram of preferred embodiment 3 of the application;

[0033] Figure 4 is a connection schematic diagram of the power-off self-braking redundant brake assembly and the caliper of preferred embodiment 3 of the application;

[0034] Figure 5 is an electrical connection schematic diagram of the power-off self-braking redundant brake assembly of preferred embodiment 3 of the application;

[0035] Reference signs: pump 1, accumulator 2, wheel cylinder 3, master cylinder 4, brake pedal 5, main oil tank 6, normally open valve 7, normally closed valve 8, auxiliary oil tank 9, normally closed leakage valve 10, first oil inlet 11, second oil inlet 12, double-cavity caliper 13, first piston 14, second piston 15, first friction plate 16, second friction plate 17. DETAILED DESCRIPTION

[0036] The application will be further described below in conjunction with the drawings and examples.

[0037] It should be noted that the following detailed description is illustrative only, and is intended to provide further description in order to provide a further understanding of the examples of the present application. Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs.

[0038] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of examples in accordance with the present application; as used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms "comprises" and / or "comprising," when used in this specification, specify the presence of stated features, steps, operations, elements, and / or components, but do not preclude the presence or addition of one or more other features, steps, operations, elements, components, and / or groups thereof.

[0039] Example 1

[0040] Redundant brake assembly with power-off self-braking, with reference to Figure 1 , comprising a pump 1, an accumulator 2, a normally open valve 7, a normally closed valve 8, and a wheel cylinder 3; the oil outlet of the pump 1 is communicated with the accumulator 2, and the oil inlet of the wheel cylinder 3 is communicated with the oil outlet of the accumulator 2 and a master cylinder 4 of a vehicle system; the accumulator 2 and the wheel cylinder 3 are connected by the normally open valve 7, and the master cylinder 4 and the wheel cylinder 3 are connected by the normally closed valve 8; the normally open valve 7 and the normally closed valve 8 are powered by a power supply of the vehicle system; the pump 1 is connected with a main oil tank 6 of the vehicle system, the main oil tank 6 is communicated with the master cylinder 4, and the master cylinder 4 is communicated with a brake pedal 5.

[0041] Control method of redundant brake assembly with power-off self-braking, based on the redundant brake assembly with power-off self-braking, comprising:

[0042] 1) Normal braking: the normally open valve 7 and the normally closed valve 8 are powered, if the brake pedal 5 is stepped down at this time, high-pressure oil generated by the brake pedal 5 enters the wheel cylinder 3 to form braking, and when the brake pedal 5 is released, the oil returns to the master cylinder 4 to remove the braking; at this time, the ECU simultaneously judges whether the pressure of the accumulator 2 is sufficient, if the pressure is insufficient, the pump 1 is controlled to work to increase the pressure in the accumulator 2;

[0043] 2) Redundant brake application: At this time, both the normally open valve 7 and the normally closed valve 8 are powered off, and the high-pressure oil in the accumulator 2 enters the brake wheel cylinder 3;

[0044] 3) Redundant brake release: When the vehicle system resumes normal, the normally closed valve 8 is powered on, and at this time the high-pressure oil flows through the normally closed valve 8 to the brake master cylinder 4, and then to the main oil tank 6.

[0045] There is a problem in Example 1 that when the normally open valve 7 is powered on, there is inevitable slight leakage, and at this time if the brake pedal 5 is depressed and the normally open valve 7 has leakage, the high-pressure oil in the accumulator 2 will gradually enter the circuit where the brake wheel cylinder 3 is located. At this time, the hydraulic oil cannot enter the main oil tank 6 through the brake master cylinder 4 (as soon as the brake pedal 5 is depressed, this circuit is mechanically closed), and at this time the wheel cylinder pressure will slowly rise, affecting the driver's feeling of braking. When the brake pedal 5 is not depressed, the brake wheel cylinder 3 pressure will also slowly rise due to the closed normally closed valve 8, so it is necessary to periodically power on the normally closed valve 8 when the brake pedal 5 is not depressed to prevent the brake wheel cylinder 3 pressure from rising. This problem is solved by further optimizing Example 1 to obtain Example 2.

[0046] Example 2

[0047] Redundant brake assembly for power-off self-braking, with reference to Figure 2 , comprising a pump 1, an accumulator 2, a normally open valve 7, a normally closed valve 8, a normally closed leakage valve 10, a secondary oil tank 9 and a brake wheel cylinder 3; the oil outlet of the pump 1 is communicated with the accumulator 2, and the oil inlet of the brake wheel cylinder 3 is communicated with the oil outlet of the accumulator 2 and the brake master cylinder 4 of the vehicle system; the accumulator 2 and the brake wheel cylinder 3 are connected by the normally open valve 7, and the brake master cylinder 4 and the brake wheel cylinder 3 are connected by the normally closed valve 8; the pump 1 is connected with the secondary oil tank 9 of the vehicle system, the brake wheel cylinder 3 is communicated with the main oil tank 6 of the vehicle system, and the brake master cylinder 4 is communicated with the brake pedal 5; the brake wheel cylinder 3 is further communicated with the secondary oil tank 9 before being connected with the normally open valve 7 and the normally closed valve 8, and the brake wheel cylinder 3 and the secondary oil tank 9 are provided with the normally closed leakage valve 10, and the normally closed leakage valve 10, the normally open valve 7 and the normally closed valve 8 are powered by the power supply of the vehicle system.

[0048] Control method of redundant brake assembly for power-off self-braking, based on the redundant brake assembly for power-off self-braking, comprising:

[0049] 1) Normal braking: Both the normally open valve 7 and the normally closed valve 8 are powered on, and when the brake pedal 5 is depressed, the oil enters the brake wheel cylinder 3 for normal braking, and at this time if there is an unexpected pressure rise, the normally closed leakage valve 10 is powered on to prevent unexpected pressure rise;

[0050] 2) Redundant brake application: none of the normally closed leakage valve 10, the normally open valve 7 and the normally closed valve 8 is energized, the high pressure oil in the accumulator 2 enters the brake wheel cylinder 3;

[0051] 3) Redundant brake release: the normally closed leakage valve 10 is energized, the oil in the brake wheel cylinder 3 enters the auxiliary oil tank 9; the oil in the brake wheel cylinder 3 enters the front end of the pump 1 through the normally closed leakage valve 10.

[0052] By separately arranging the auxiliary oil tank 9 inside the redundant brake system, the redundant brake system is provided with one less oil inlet, and the integration degree is increased.

[0053] Embodiment 3

[0054] In order to reduce one electromagnetic valve, embodiment 3 is further improved on the basis of embodiment 2, referring to Figures 3-5 The redundant brake assembly with power-off self-braking comprises a pump 1, an accumulator 2, a normally open valve 7, a normally closed leakage valve 10, an auxiliary oil tank 9 and a brake wheel cylinder 3; the brake wheel cylinder 3 is provided with a first oil inlet 11 and a second oil inlet 12; an oil outlet of the pump 1 is communicated with the accumulator 2, the first oil inlet 11 of the brake wheel cylinder 3 is communicated with an oil outlet of the accumulator 2, and the second oil inlet 12 of the brake wheel cylinder 3 is communicated with a brake master cylinder 4 of a vehicle system; the accumulator 2 and the brake wheel cylinder 3 are connected with the normally open valve 7; the pump 1 is connected with the auxiliary oil tank 9 of the vehicle system, the brake wheel cylinder 3 is communicated with a main oil tank 6 of the vehicle system, and the brake master cylinder 4 is communicated with a brake pedal 5; the brake wheel cylinder 3 is further communicated with the auxiliary oil tank 9 before being connected with the normally open valve 7, the normally closed leakage valve 10 is arranged between the brake wheel cylinder 3 and the auxiliary oil tank 9, and the normally closed leakage valve 10 and the normally open valve 7 are powered by a power supply of the vehicle system.

[0055] The control method of the redundant brake assembly with power-off self-braking is based on the redundant brake assembly with power-off self-braking and comprises the following steps:

[0056] 1) Normal braking: at this time, the normally open valve 7 is energized, the normally closed leakage valve 10 is de-energized, and when the brake pedal 5 is stepped on, the oil enters the brake wheel cylinder 3 through the second oil inlet 12 to brake normally;

[0057] 2) Redundant brake application: at this time, the normally open valve 7 is de-energized and the normally closed leakage valve 10 is de-energized, and the oil in the accumulator 2 enters the brake wheel cylinder 3 through the first oil inlet 11 to brake;

[0058] 3) Redundant brake release: the normally closed leakage valve 10 is energized, and the oil in the brake wheel cylinder 3 enters the auxiliary oil tank 9.

[0059] The redundant brake system based on the tandem double-cavity caliper is used in the redundant brake assembly of the power-off self-braking, and comprises a double-cavity caliper 13, wherein the double-cavity caliper 13 comprises a piston cavity and a movable cavity; the piston cavity is communicated with the movable cavity; a first piston 14 and a second piston 15 which are independent of each other are arranged in the piston cavity; the first piston 14 and the second piston 15 are provided with elastic elements in the middle; one end of the first piston 14 away from the second piston 15 is arranged close to the right cavity bottom of the piston cavity; the right cavity bottom of the piston cavity is provided with a first connecting port communicated with a first oil inlet 11; the lower bottom of the piston cavity between the first piston 14 and the second piston 15 is provided with a second connecting port communicated with a second oil inlet 12; the left opening of the piston cavity is communicated with the movable cavity; one end of the second piston 15 away from the first piston 14 is provided with a first friction plate 16, and one side of the movable cavity facing the second piston 15 is provided with a second friction plate 17.

[0060] The oil liquid of the first oil inlet 11 is responsible for pushing the first piston 14 to move left, and the second oil inlet 12 is responsible for pushing the second piston 15 to move left; in the normal state, that is, when the oil inlet of the first piston 14 is not supplied with oil, the first piston 14 is tightly attached to the right limit of the caliper body; at this time, the second oil inlet 12 is not blocked by the first piston 14, and the second piston 15 is located at the left end of the second oil inlet 12 in the normal state, that is, when the oil inlet of the second piston 15 is not supplied with oil, the second piston 15 does not block the second oil inlet 12; when the first piston 14 moves left under the action of the oil liquid, the second oil inlet 12 is blocked, and the first piston 14 still blocks the second oil inlet 12 when it moves to the left end limit.

[0061] The working principle is as follows:

[0062] The first case: the first oil inlet 11 is supplied with oil, the first piston 14 moves left, and then pushes the second piston 15 to move left, the first friction plate 16 and the second friction plate 17 gradually approach the clamped brake disc to realize braking; at this time, if the first piston 14 has blocked the second oil inlet 12, the oil supplied at the second oil inlet 12 will not affect the state of the first piston 14 and the second piston 15;

[0063] The second case: if the second piston 15 is supplied with oil, the first piston 14 is pushed to the right limit position, and the second piston 15 is pushed to the left to generate braking; if the first oil inlet 11 also applies oil at this time, if the pressure in the first oil inlet 11 is greater than the pressure in the second oil inlet 12, the first piston 14 will be pushed to the left end, and then work according to the principle in the first case.

[0064] There are two connection methods for the double-cavity caliper 13. The first inlet 11 is connected to redundancy, and the second inlet 12 is connected to normality. At this time, no matter how large the pressure in the second inlet 12 is, as long as the pressure applied by redundancy is larger, a larger braking force can be generated to act on the first friction plate 16 and the second friction plate 17, and at the same time, due to the small amount of stroke of the first piston 14, a small amount of leakage in redundancy will not generate braking. If the first inlet 11 is connected to normality and the second inlet 12 is connected to redundancy, then at this time, once the normal brake is stepped on, the redundancy brake cannot function.

[0065] Based on the application of the redundancy brake system based on the tandem double-cavity caliper, based on the redundancy brake system based on the tandem double-cavity caliper; the redundancy brake system is connected with the vehicle, wherein the electromagnetic valve control line of the vehicle system is connected with the electromagnetic valve of the redundancy brake system, for controlling the electromagnetic valve, the electromagnetic valve includes a normally open valve 7, a normally closed valve 8 and a normally closed leakage valve 10, the vehicle CAN line is connected with the vehicle, for receiving information and instructions of the vehicle, and the emergency stop is used for controlling the power supply of the redundancy brake ECU;

[0066] The redundancy brake system has the following modes:

[0067] Mode 1 is to brake according to the emergency stop switch: when the emergency stop switch is pressed, the redundancy brake ECU is powered off, and the normally open valve 7 of the redundancy brake system returns to the connected state, and the oil in the accumulator 2 directly enters the brake wheel cylinder 3;

[0068] Mode 2 is to receive CAN to judge heartbeat to perform emergency braking: it is judged that the main brake system fails, and the redundancy brake mode is entered;

[0069] Mode 3 is to receive CAN redundancy brake instruction: if the main brake system sends a fault information that the main brake is unavailable on the CAN, or sends a request for redundancy brake information, the redundancy brake ECU control enters the redundancy brake mode;

[0070] Mode 4 is to receive CAN to judge deceleration request and actual deceleration: step 1) receiving the request a of the main brake system for requesting deceleration on the CAN cmd , calculating the actual deceleration by vehicle speed , wherein n represents the number of speed sampling points, represents the derivative value of the differential value of the speed v at the time point i before the current time point, and n is 10; step 2) calculating the danger index, which means that the larger the acceleration deviation or the longer the acceleration error lasts, the greater the danger, and the calculation method is J i =[J i-1 +f(-(a cmd -a r ))]*K, wherein J i is the danger index at the current time, Ji-1 is the index of the dangerous degree of the last cycle, f(*) is the dangerous degree mapping function, which can be taken as , which means that when a cmd -a r <0, the actual deceleration is greater than the expected deceleration, at this time the main brake system is not a problem, when a cmd -a r >0, the greater the deceleration error, that is, the more likely the main brake system to appear problems; 0 < K < 1, K is the attenuation coefficient, taken 0.8, used to make a period of time after the danger does not appear, then J gradually decreases to 0; step 3): to determine whether J i exceeds the preset threshold J Thre , take 1500, if it exceeds, it means that the degree of danger is too large, and the redundant brake should be involved.

Claims

1. Redundant braking system based on tandem double chamber calipers, characterized in that, The application relates a redundant brake assembly for power-off self-braking, comprising a double-cavity caliper, wherein the double-cavity caliper comprises a piston cavity and a movable cavity; the piston cavity is communicated with the movable cavity; a first piston and a second piston which are independent of each other are arranged in the piston cavity; the first piston and the second piston are provided with elastic elements in the middle; one end of the first piston away from the second piston is arranged close to the right cavity bottom of the piston cavity; the right cavity bottom of the piston cavity is provided with a first connecting port communicated with a first oil inlet; the lower bottom of the piston cavity between the first piston and the second piston is provided with a second connecting port communicated with a second oil inlet; the left opening of the piston cavity is communicated with the movable cavity; the second piston is provided with a first friction plate at one end away from the first piston; one side of the movable cavity facing the second piston is provided with a second friction plate; the redundant brake assembly for power-off self-braking comprises a pump, an accumulator, a normally-open valve, a normally-closed valve and a brake cylinder; the oil outlet of the pump is communicated with the accumulator; the oil inlet of the brake cylinder is communicated with the oil outlet of the accumulator and a brake master cylinder of a vehicle system; the accumulator and the brake cylinder are connected with the normally-open valve; the brake master cylinder and the brake cylinder are connected with the normally-closed valve; the normally-open valve and the normally-closed valve are powered by a power supply of the vehicle system.

2. The redundant brake system based on tandem double cavity caliper according to claim 1, characterized in that, The application further relates to a control method of the redundant brake assembly for power-off self-braking, comprising the following steps: 1) normal braking: the normally-open valve and the normally-closed valve are powered on; if the brake pedal is stepped down at this time, high-pressure oil generated by the brake pedal enters the brake cylinder to form braking; when the brake pedal is released, the oil returns to the brake master cylinder to remove the braking; at this time, the ECU simultaneously judges whether the pressure of the accumulator is sufficient; if the pressure is insufficient, the pump is controlled to work to increase the pressure in the accumulator; 2) redundant braking application: at this time, the normally-open valve and the normally-closed valve are powered off; high-pressure oil in the accumulator enters the brake cylinder; 3) redundant braking removal: when the vehicle system is restored to normal, the normally-closed valve is powered on; at this time, high-pressure oil flows to the brake master cylinder through the normally-closed valve and then flows to a main oil pot.

3. Redundant braking system based on tandem double chamber calipers, characterized in that, The application relates to a redundant brake assembly for power-off self-braking, comprising a double-cavity caliper, wherein the double-cavity caliper comprises a piston cavity and a movable cavity; the piston cavity is communicated with the movable cavity; a first piston and a second piston which are independent of each other are arranged in the piston cavity; the first piston and the second piston are provided with elastic elements in the middle; one end of the first piston which is away from the second piston is arranged close to the right cavity bottom of the piston cavity; the right cavity bottom of the piston cavity is provided with a first connecting port communicated with a first oil inlet; the lower bottom of the piston cavity between the first piston and the second piston is provided with a second connecting port communicated with a second oil inlet; the left opening of the piston cavity is communicated with the movable cavity; the second piston is provided with a first friction plate at one end which is away from the first piston; the movable cavity is provided with a second friction plate on one side which faces the second piston; the redundant brake assembly for power-off self-braking comprises a pump, an accumulator, a normally-open valve, a normally-closed valve, a normally-closed leakage valve, a secondary oil pot and a brake cylinder; the oil outlet of the pump is communicated with the accumulator; the oil inlet of the brake cylinder is communicated with the oil outlet of the accumulator and a brake master cylinder of a vehicle system; the accumulator and the brake cylinder are connected with the normally-open valve; the brake master cylinder and the brake cylinder are connected with the normally-closed valve; the pump is connected with the secondary oil pot of the vehicle system; the brake cylinder is further communicated with the secondary oil pot before being connected with the normally-open valve and the normally-closed valve; the normally-closed leakage valve is arranged between the brake cylinder and the secondary oil pot; the normally-closed leakage valve, the normally-open valve and the normally-closed valve are powered by a power supply of the vehicle system.

4. The redundant brake system based on series dual cavity caliper according to claim 3, characterized in that, The application further relates to a control method of the redundant brake assembly for power-off self-braking, comprising the following steps: 1) normal braking: the normally-open valve and the normally-closed valve are powered, when a brake pedal is stepped on, oil enters the brake cylinder to realize normal braking, if there is an unexpected pressure rise, the normally-closed leakage valve is powered to prevent the unexpected pressure rise; 2) redundant brake application: the normally-closed leakage valve, the normally-open valve and the normally-closed valve are not powered, high-pressure oil in the accumulator enters the brake cylinder; 3) redundant brake removal: the normally-closed leakage valve is powered, oil in the brake cylinder enters the secondary oil pot; the oil in the brake cylinder enters the front end of the pump through the normally-closed leakage valve.

5. Redundant braking system based on tandem double chamber calipers, characterized in that, The application relates to a redundant brake assembly for power-off self-braking, which comprises a double-cavity caliper, wherein the double-cavity caliper comprises a piston cavity and a movable cavity; the piston cavity is communicated with the movable cavity; a first piston and a second piston which are independent of each other are arranged in the piston cavity; the first piston and the second piston are provided with elastic elements in the middle; the end of the first piston away from the second piston is arranged close to the right cavity bottom of the piston cavity; the right cavity bottom of the piston cavity is provided with a first connecting port communicated with a first oil inlet; the lower bottom of the piston cavity between the first piston and the second piston is provided with a second connecting port communicated with a second oil inlet; the left side opening of the piston cavity is communicated with the movable cavity; the end of the second piston away from the first piston is provided with a first friction plate; the side of the movable cavity facing the second piston is provided with a second friction plate; the redundant brake assembly for power-off self-braking comprises a pump, an accumulator, a normally-open valve, a normally-closed leakage valve, a secondary oil pot and a brake wheel cylinder; the brake wheel cylinder is provided with a first oil inlet and a second oil inlet; the oil outlet of the pump is communicated with the accumulator; the first oil inlet of the brake wheel cylinder is communicated with the oil outlet of the accumulator; the second oil inlet of the brake wheel cylinder is communicated with a brake master cylinder of a vehicle system; the accumulator and the brake wheel cylinder are connected with the normally-open valve; the pump is connected with the secondary oil pot of the vehicle system; the brake wheel cylinder is further communicated with the secondary oil pot before being connected with the normally-open valve; the normally-closed leakage valve is arranged between the brake wheel cylinder and the secondary oil pot; and the normally-open valve and the normally-closed leakage valve are powered by a power supply of the vehicle system.

6. The redundant brake system based on series double cavity caliper according to claim 5, characterized in that, The control method of the redundant brake assembly for power-off self-braking comprises the following steps: 1) normal braking: at this time, the normally-open valve is powered on, and the normally-closed leakage valve is powered off; when a brake pedal is stepped on, oil enters the brake wheel cylinder through the second oil inlet to realize normal braking; 2) redundant brake application: at this time, the normally-open valve and the normally-closed leakage valve are powered off; oil in the accumulator enters the brake wheel cylinder through the first oil inlet to realize braking; 3) redundant brake removal: the normally-closed leakage valve is powered on; oil in the brake wheel cylinder enters the secondary oil pot.

7. The redundant brake system based on series dual chamber caliper according to claim 1, 3 or 5, characterized in that, The oil in the first oil inlet is responsible for pushing the first piston to move leftwards; the second oil inlet is responsible for pushing the second piston to move leftwards; in a normal state, the first piston is close to the right limit of the caliper body when the oil inlet of the first piston is not supplied with oil; at this time, the second oil inlet is not blocked by the first piston; in a normal state, the second piston is located at the left end of the second oil inlet when the oil inlet of the second piston is not supplied with oil; the first piston is blocked from moving leftwards when the oil inlet of the first piston is supplied with oil; the first piston is still blocked from moving leftwards when the first piston moves to the left end limit.

8. The redundant brake system based on series double cavity caliper according to claim 7, characterized in that, The working principle is as follows: In the first case, the first oil inlet is supplied with oil; the first piston moves leftwards and pushes the second piston to move leftwards; the first friction plate and the second friction plate gradually approach the clamped brake disc to realize braking; if the first oil inlet is supplied with oil when the first piston blocks the second oil inlet, the state of the first piston and the second piston will not be affected. The second case: if the second piston is supplied with oil, the first piston is pushed to the right limit position, and the second piston is pushed to the left to generate braking; if the first oil inlet also supplies oil at this time, if the pressure in the first oil inlet is greater than the pressure in the second oil inlet, the first piston will be pushed to the left end, and then work according to the principle in the first case.

9. Use of a redundant braking system based on tandem double chamber calipers, characterized in that The series double-cavity caliper-based redundant brake system according to any one of claims 1, 3, and 5; the redundant brake system is connected with a vehicle, wherein an electromagnetic valve control line of a vehicle system is connected with an electromagnetic valve of the redundant brake system, for controlling the electromagnetic valve, a vehicle CAN line is connected with the vehicle, for receiving information and instructions of the vehicle, and an emergency stop is used for controlling power supply of the redundant brake ECU; The redundant brake system has the following modes: Mode 1 is brake according to the emergency stop switch: after the emergency stop switch is pressed, the redundant brake ECU is powered off, at this time the normally open valve of the redundant brake system returns to the connected state, and the oil in the accumulator directly enters the brake wheel cylinder; Mode 2 is to receive CAN to judge heartbeat to perform emergency braking: it is judged that the main brake system has a fault, and the redundant brake mode is entered; Mode 3 is to receive CAN redundant brake instructions: at this time, if the main brake system sends a fault information that the main brake is not available on the CAN, or sends a request for redundant brake information, the redundant brake ECU control enters the redundant brake mode; Mode 4 is to receive CAN to judge deceleration request and actual deceleration: step 1) receiving the request a of the master braking system to request deceleration on CAN cmd , calculating the actual deceleration by vehicle speed , n represents the number of speed sampling points, derivative of the speed v at the time point before the current time point i; step 2) calculating the danger degree index, the meaning of the index is that the greater the acceleration deviation or the longer the time of the acceleration error, the greater the danger degree, and the calculation method is J i = [J i-1 + f(-(a cmd -a r ))]*K, wherein J i is the danger degree index at the current time point, J i-1 is the danger degree index at the last cycle, f(*) is a danger degree mapping function, and the meaning is that when a cmd -a r <0, the actual deceleration is greater than the expected deceleration, and at this time, the master braking system is normal, and when a cmd -a r >0, the greater a i -a Thre is, the greater the deceleration error is, that is, the master braking system is more likely to have a problem; 0<K<1, K is an attenuation coefficient, and is used to make J gradually decrease to 0 after a period of time without danger; step 3) judging whether J i exceeds a preset threshold J Thre , and if yes, it indicates that the danger degree is too large, and the redundant braking should be intervened.

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