Redundant brake system control circuit with power-off automatic braking

Abstract

The application provides a redundant brake system control circuit and a power-off automatic brake system. The system executes brake through a bidirectional valve system with memory function, and the bidirectional valve system is controlled by the redundant brake control circuit to have the power-off automatic brake capability. The bidirectional valve system comprises an electromagnetic valve for brake, a main brake controller and a redundant brake controller. The control method of the redundant brake comprises the following steps. Step one, the main brake controller and the redundant brake controller judge whether the working conditions of each other are normal through a communication network. Step two, the main brake controller controls the electromagnetic valve according to the brake demand to avoid the misoperation of the electromagnetic valve caused by the abnormal power-off of the redundant brake controller. Step three, the redundant controller judges whether the brake is needed according to the power supply condition of the brake system and the working condition of the main brake controller, and controls the electromagnetic valve when the brake is needed. The application can provide the redundant control of the brake system under the power-off condition for the vehicle.

Description

Technical Field

[0001] This invention relates to the field of vehicle equipment technology, and in particular to redundant braking system control circuits and automatic braking systems in the event of power failure. Background Technology

[0002] Redundancy in the braking system is a crucial feature of autonomous vehicles, preventing operational hazards caused by the failure of one braking system. Patent CN202311024440.6 proposes a redundant braking system that uses a dual-way check valve (shuttle valve) to switch the braking source. An electronically controlled proportional valve serves as redundancy; when energized, it outputs a certain pressure. The dual-way check valve outputs the greater of the pressure from the connection between the proportional valve and the angle valve. This means that even if the angle valve fails, braking can still be achieved by controlling the proportional valve, thus achieving braking redundancy. However, in this patent, if the vehicle loses power, the proportional valve also fails, and the vehicle loses braking. Therefore, in systems with particularly high redundancy requirements (such as high-speed rail and subways), this system cannot meet the requirement of maintaining braking function even in the event of power failure. An easy solution that engineers in this field would consider is to use a solenoid valve that automatically resets upon power failure in conjunction with a high-pressure source. When the system is powered off, the state of the solenoid valve changes, thereby changing the braking state from non-braking to braking. However, this solution requires continuous power to the solenoid valve to maintain the non-braking state when the system is normal. This poses two risks: 1) Continuous power to the solenoid valve will cause the solenoid valve coil and circuit to heat up continuously, which will shorten the lifespan of the system; 2) Interference in the circuit can easily cause the solenoid valve to disconnect intermittently, which can lead to unexpected braking.

[0003] Patent CN207089288U describes a two-way parking valve with a memory function. This parking valve has two control input terminals. When the two control input terminals are energized respectively, the solenoid valve will be in two different states. When the power is off, the state of the solenoid valve will not change. This system effectively avoids the problem of the solenoid valve being continuously energized. However, because it does not have a self-resetting function, it cannot achieve the function of automatic braking when the power is off.

[0004] Therefore, this invention designs a new circuit, which, together with a bidirectional valve with memory function, forms a braking system that realizes automatic braking function in the event of power failure. Summary of the Invention

[0005] This invention proposes a redundant braking system control circuit and an automatic braking system in the event of a power failure, which can provide redundant control of the braking system in the event of a power failure.

[0006] The present invention adopts the following technical solution.

[0007] A redundant braking system control circuit and a system for automatic braking upon power failure, wherein the system is a braking system that performs braking through a two-way valve system with memory function, and uses a redundant braking control circuit to perform redundant braking control on the two-way valve system, so that it has the ability to automatically brake upon power failure.

[0008] The bidirectional valve system includes a solenoid valve for braking and a main brake controller and a redundant brake controller connected to the solenoid valve.

[0009] The control method for redundant braking includes the following steps;

[0010] Step 1: The main brake controller and the redundant brake controller determine each other's operating conditions via the communication network.

[0011] Step 2: The main brake controller controls the solenoid valve according to the braking demand to avoid malfunction of the solenoid valve caused by abnormal power failure of the redundant brake controller.

[0012] Step 3: The redundant controller determines whether braking is needed based on the power supply status of the braking system and the operating status of the main controller, and controls the solenoid valve when braking is required.

[0013] The braking system is used for vehicle braking. The main brake controller is used for the normal operating conditions of the two-way valve system, and the redundant brake controller is used for the abnormal operating conditions of the two-way valve system. Both the main brake controller and the redundant brake controller are connected to the communication network.

[0014] The solenoid valve is a two-position three-way valve including terminals a, b, and c. In the two-way valve system, the power supply terminal of the main brake controller includes a power source and a ground. The power supply terminal is connected to the battery. Terminals a and b are used to control the state switching of the two-position three-way valve.

[0015] The two-position three-way valve has two operating conditions: state A and state B, which are respectively: the air supply end of the vehicle braking mechanism is connected to the brake wheel cylinder and the exhaust end is cut off; and the exhaust end of the vehicle braking mechanism is connected to the brake wheel cylinder and the air supply end is cut off.

[0016] The terminals b and c of the two-position three-way valve are used to control state B, and the terminal a of the two-position three-way valve is used to control state A. That is, when terminal a is energized, the two-position three-way valve operates in state A, and when terminal b is energized, the two-position three-way valve operates in state B. De-energizing will not cause the state of the two-position three-way valve to change.

[0017] In step one, the main brake controller sends a broadcast signal with predetermined characteristics and uniqueness to the communication network connected to it, so that the redundant controller can determine whether the main brake controller is normal based on whether the signal exists in the communication network; when the broadcast signal does not exist, or the broadcast signal is abnormal, or the main controller actively broadcasts a fault code, the redundant controller determines that the main brake is abnormal.

[0018] Similarly, the redundant brake controller also sends a unique broadcast signal with predetermined characteristics to the communication network connected to it, so that the main brake controller can determine whether the redundant brake controller is normal based on whether the signal exists in the communication network; when the broadcast signal does not exist, or the broadcast signal is abnormal, or the redundant controller actively broadcasts a fault code, the main brake controller determines that the redundant brake controller is abnormal.

[0019] The broadcast signals sent by the main brake controller and the redundant brake controller are characterized by being sent at predetermined intervals, and the value of the broadcast signal changes cyclically. For example, it can change 0, 1, 2, 3...253, 254, 255, 0, 1.. every 20ms.

[0020] In step two, if the main brake controller does not require braking, it intermittently controls the solenoid valve a terminal of the two-way valve system to be energized (e.g., energized for 0.1s and de-energized for 5s) to prevent the solenoid valve from being in a braking state due to abnormal power failure of the redundant brake controller.

[0021] If the main brake controller needs to brake, or if it receives a braking instruction from the vehicle communication network, it will energize the b end of the control solenoid valve, causing the solenoid valve to switch to the braking state.

[0022] The redundant braking controller includes redundant braking control circuitry, such as... Figure 1 As shown, the redundant braking control circuit includes a storage element C1 and an external circuit. When there is voltage at the Vext terminal of the redundant braking control circuit, the external circuit charges the storage element, and at this time there is no voltage at the Vout terminal of the redundant braking control circuit. When there is no voltage at the Vext terminal, the external circuit outputs the electrical energy in the storage element and outputs voltage at the Vout terminal to change the state of the solenoid valve.

[0023] The energy storage capacity of the energy storage element C1 is at least sufficient to meet the energy required to change the primary state of the solenoid valve. Assume the load current is... The power-on time is The minimum operating voltage of the solenoid valve is The energy storage capacity of the energy storage element can be expressed by the formula:

[0024] ,

[0025] In the formula It is the external input voltage. It is the voltage drop of the diode (typically 0.7V), and the typical value of the energy storage element is 0.05F.

[0026] The energy storage element is a capacitor or a battery;

[0027] In the redundant braking control circuit, Vext is the power supply terminal, Vout is the output terminal, GND is ground, R1 and R2 are voltage divider resistors, R3 is a pull-up resistor, R4 is a pull-down resistor, Q1 is an NPN transistor, M1 is an N-channel MOSFET, and D1 and D2 are input diodes. The base, collector, and emitter on the transistor are the base, collector, and emitter, respectively; the gate, drain, and source on the MOSFET are the gate, drain, and source, respectively.

[0028] The function of D1 is to prevent the power supply of the redundant braking control circuit from being reversed and to prevent the energy storage element from discharging to the outside through Vest.

[0029] The function of C1 is to store energy and enable output during power outages.

[0030] The function of Q1 is to control the gate of the MOSFET;

[0031] The function of R1 and R2 is to divide the voltage and drive the base of the transistor.

[0032] The function of R3 is to pull up the gate G when the transistor is not conducting.

[0033] The function of R4 is to pull down the source S;

[0034] D2: Ensures unidirectional output of redundant braking control circuit;

[0035] The redundant braking control circuit is specifically connected as follows: the P-terminal of diode D1 is connected to Vext, and the N-terminal is connected to capacitor C1, resistor R3, and the drain of the MOSFET; one end of C1 is connected to the N-terminal of diode D1, resistor R3, and the drain of MOSFET M1, and the other end is connected to GND; one end of R1 is connected to the P-terminal of diode D1, and the other end is connected to the base of transistor Q1; one end of R3 is connected to the N-terminal of D1, capacitor C1, and the drain of the MOSFET, and the other end is connected to the collector of transistor Q1 and the gate of MOSFET M1; the drain of MOSFET M1 is connected to the N-terminal of D1, resistor R3, and capacitor C1; the gate of MOSFET M1 is connected to resistor R3 and the collector of transistor Q1; the source (S) terminal of MOSFET M1 is connected to resistor R4 and the P-terminal of diode D2; the collector of transistor Q1 is connected to resistor R3 and the gate of MOSFET M1. The base (b) of transistor Q1 is connected to resistors R2 and R1, and the emitter (e) of transistor Q1 is connected to ground and resistors R2 and R4. The point (p) of diode D2 is connected to resistor R4 and the source (s) of MOSFET M1, and the neutral (n) of diode D2 is connected to Vout. One end of R2 is connected to the base (b) of transistor Q1 and R1, and the other end is connected to the emitter (e) of transistor Q1, R4, and GND. One end of R2 is connected to the point (p) of diode D2 and the source (s) of MOSFET M1, and the other end is connected to the emitter (e) of transistor Q1, R2, and GND.

[0036] The power supply method for the redundant braking control circuit is as follows: (See details below) Figure 3Powered by battery Vbat;

[0037] With a 12V supply voltage, a suitable component selection for this function is as follows: D1 and D2 are 1N4007, C1 is a 0.05F / 16V electrolytic capacitor, Q1 is a 2N3904, R1=15KΩ, R2=6.8KΩ, R3=10KΩ, R4=1KΩ, and the MOSFET is an IRLZ44N.

[0038] The working method of the redundant braking control circuit is as follows: When there is a voltage in Vest, Vest powers the energy storage element C1. At the same time, it acts as a voltage divider for R1 and R2, and the b point is at a high level, causing the transistor to conduct. At this time, G is pulled low, causing the MOS to turn off. Vout outputs a low level due to the pull-down of R4.

[0039] When there is no voltage at Vest, b is at a low level. At this time, c and e are not conducting. Since the current flowing into G is very small (this needs to be designed separately), G is still at a high level. At this time, MOS is conducting, that is, the drain and source of MOS transistor are conducting, and the voltage at C1 is output through Vout.

[0040] The redundant controller also includes an MCU, the principle of which is as follows: Figure 2 As shown in the figure, the redundant braking circuit is as follows: Figure 1 The base, collector, and emitter of the transistor are b, c, and e, respectively; the power supply terminal of the MCU is Vbat, and the MCU is connected to an external communication network. The MCU switches the redundant braking circuit operating condition by controlling the MCU pin connected to the base of the transistor to be high or low.

[0041] When the base of the transistor is connected to a low level, the collector and emitter of the transistor are disconnected, and the redundant braking circuit is de-energized. When the base of the transistor is connected to a high level, the collector and emitter of the transistor are connected, and the output Vout of the redundant braking circuit is connected to the collector (c) of the two-position three-way valve.

[0042] In step three, when the system is powered off, the redundant controller automatically energizes the c-end of the two-position three-way valve, causing the solenoid valve state of the two-position three-way valve to switch to the braking state.

[0043] When the redundant braking controller determines that the main braking controller is abnormal, the control MCU outputs a low level at the b pin of the transistor. At this time, there is no voltage input to Vext, which switches the state of the solenoid valve of the two-position three-way valve to the state that requires braking.

[0044] In the braking system, the brake wheel cylinder has two braking modes: the service brake wheel cylinder mode, which brakes when air is supplied to the brake wheel cylinder, and the parking brake wheel cylinder mode, which brakes when no air is supplied to the brake wheel cylinder.

[0045] The two-position three-way valve adopts a slide valve structure and does not have a return spring;

[0046] In the parking brake wheel cylinder method, the power-off braking requires controlling the exhaust of the brake wheel cylinder when the power is off. In the settings of state B and state A of its two-position three-way valve, when state B, i.e., when the c end is energized, the exhaust end is connected to the brake wheel cylinder and the air supply end is cut off. When state A, i.e., when the a end is energized, the air supply end is connected to the brake wheel cylinder and the exhaust end is cut off.

[0047] In the parking brake wheel cylinder system, one example of a two-position three-way valve is: Figure 4 As shown, when the coil controlled by end a is energized, the slide valve moves to the left (the solenoid valve is in the state shown in the right square diagram). Ends b and c each have a set of coils, making ends b and c electrically independent. Controlling end b will not affect the circuit of end c, and controlling end c will not affect the circuit of end b. Both can control the slide valve to move to the right (the solenoid valve is in the state shown in the left square diagram), achieving the required function. Under the condition that b and c are electrically independent, the D2 diode in the redundant braking control circuit is unnecessary. Another implementation method is that b and c are not electrically independent, such as... Figure 5 As shown, b and c are two terminals connected to the same coil. The valve works on the same principle, but the D2 diode in the redundant braking control circuit needs to be equipped.

[0048] In the service brake wheel cylinder system, the valve core needs to be swapped between left and right during the production of the two-position three-way valve, such as... Figure 4 As shown, to be compatible with the braking system, that is: if power-off braking is required, the air intake of the brake wheel cylinder needs to be controlled when power is off. In the settings of state B and state A of the two-position three-way valve, state B is when the c end is energized, the air supply end is connected to the brake wheel cylinder and the exhaust end is cut off. State A is when the a end is energized, the exhaust end is connected to the brake wheel cylinder and the air supply end is cut off.

[0049] In the service brake wheel cylinder system, one example of a two-position three-way valve is: Figure 6 As shown, when the coil controlled by end a is energized, the slide valve moves to the left (the solenoid valve is in the state shown in the right square diagram); when end b is energized, the slide valve moves to the right (the solenoid valve is in the state shown in the left square diagram). The method of setting b and c to share a single coil is as follows: Figure 5 As shown.

[0050] This invention proposes a novel circuit, which, in conjunction with a bidirectional valve with memory function, forms a braking system that achieves automatic braking upon power failure. The main braking system and the redundant braking system verify each other's operating conditions through a communication line, eliminating the need to continuously supply power to the solenoid valve to maintain the non-braking state when the system is normal. Furthermore, this invention has a self-resetting function, enabling automatic braking upon power failure. Attached Figure Description

[0051] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments:

[0052] Appendix Figure 1 This is a schematic diagram of the redundant braking control circuit in an embodiment of the present invention;

[0053] Appendix Figure 2 This is a schematic diagram of the automatic braking system in an embodiment of the present invention.

[0054] Appendix Figure 3 This is a schematic diagram of the redundant braking controller in an embodiment of the present invention;

[0055] Appendix Figure 4 This is a schematic diagram of the operation of a two-position three-way solenoid valve in the parking brake wheel cylinder mode, where the b and c ends are respectively equipped with independent coils (electrically independent).

[0056] Appendix Figure 5 This is a schematic diagram of the operation of a two-position three-way solenoid valve in the parking brake wheel cylinder mode when the b and c ends share a common coil (electrically not independent) in an embodiment of the present invention.

[0057] Appendix Figure 6 This is a schematic diagram of the operation of a two-position three-way solenoid valve in the service brake wheel cylinder mode in an embodiment of the present invention (b and c share a single coil). Detailed Implementation

[0058] As shown in the figure, the redundant braking system control circuit and the power failure automatic braking system are described. The system is a braking system that performs braking through a two-way valve system with memory function, and the redundant braking control circuit performs redundant braking control on the two-way valve system to enable it to have the ability to automatically brake when power is lost.

[0059] The bidirectional valve system includes a solenoid valve for braking and a main brake controller and a redundant brake controller connected to the solenoid valve.

[0060] The control method for redundant braking includes the following steps;

[0061] Step 1: The main brake controller and the redundant brake controller determine each other's operating conditions via the communication network.

[0062] Step 2: The main brake controller controls the solenoid valve according to the braking demand to avoid malfunction of the solenoid valve caused by abnormal power failure of the redundant brake controller.

[0063] Step 3: The redundant controller determines whether braking is needed based on the power supply status of the braking system and the operating status of the main controller, and controls the solenoid valve when braking is required.

[0064] The braking system is used for vehicle braking. The main brake controller is used for the normal operating conditions of the two-way valve system, and the redundant brake controller is used for the abnormal operating conditions of the two-way valve system. Both the main brake controller and the redundant brake controller are connected to the communication network.

[0065] The solenoid valve is a two-position three-way valve including terminals a, b, and c. In the two-way valve system, the power supply terminal of the main brake controller includes a power source and a ground. The power supply terminal is connected to the battery. Terminals a and b are used to control the state switching of the two-position three-way valve.

[0066] The two-position three-way valve has two operating conditions: state A and state B, which are respectively: the air supply end of the vehicle braking mechanism is connected to the brake wheel cylinder and the exhaust end is cut off; and the exhaust end of the vehicle braking mechanism is connected to the brake wheel cylinder and the air supply end is cut off.

[0067] The terminals b and c of the two-position three-way valve are used to control state B, and the terminal a of the two-position three-way valve is used to control state A. That is, when terminal a is energized, the two-position three-way valve operates in state A, and when terminal b is energized, the two-position three-way valve operates in state B. De-energizing will not cause the state of the two-position three-way valve to change.

[0068] In step one, the main brake controller sends a broadcast signal with predetermined characteristics and uniqueness to the communication network connected to it, so that the redundant controller can determine whether the main brake controller is normal based on whether the signal exists in the communication network; when the broadcast signal does not exist, or the broadcast signal is abnormal, or the main controller actively broadcasts a fault code, the redundant controller determines that the main brake is abnormal.

[0069] Similarly, the redundant brake controller also sends a unique broadcast signal with predetermined characteristics to the communication network connected to it, so that the main brake controller can determine whether the redundant brake controller is normal based on whether the signal exists in the communication network; when the broadcast signal does not exist, or the broadcast signal is abnormal, or the redundant controller actively broadcasts a fault code, the main brake controller determines that the redundant brake controller is abnormal.

[0070] The broadcast signals sent by the main brake controller and the redundant brake controller are characterized by being sent at predetermined intervals, and the value of the broadcast signal changes cyclically. For example, it can change 0, 1, 2, 3...253, 254, 255, 0, 1.. every 20ms.

[0071] In step two, if the main brake controller does not require braking, it intermittently controls the solenoid valve a terminal of the two-way valve system to be energized (e.g., energized for 0.1s and de-energized for 5s) to prevent the solenoid valve from being in a braking state due to abnormal power failure of the redundant brake controller.

[0072] If the main brake controller needs to brake, or if it receives a braking instruction from the vehicle communication network, it will energize the b end of the control solenoid valve, causing the solenoid valve to switch to the braking state.

[0073] The redundant braking controller includes redundant braking control circuitry, such as... Figure 1 As shown, the redundant braking control circuit includes a storage element C1 and an external circuit. When there is voltage at the Vext terminal of the redundant braking control circuit, the external circuit charges the storage element, and at this time there is no voltage at the Vout terminal of the redundant braking control circuit. When there is no voltage at the Vext terminal, the external circuit outputs the electrical energy in the storage element and outputs voltage at the Vout terminal to change the state of the solenoid valve.

[0074] The energy storage capacity of the energy storage element C1 is at least sufficient to meet the energy required to change the primary state of the solenoid valve. Assume the load current is... The power-on time is The minimum operating voltage of the solenoid valve is The energy storage capacity of the energy storage element can be expressed by the formula:

[0075] ,

[0076] In the formula It is the external input voltage. It is the voltage drop of the diode (typically 0.7V), and the typical value of the energy storage element is 0.05F.

[0077] The energy storage element is a capacitor or a battery;

[0078] In the redundant braking control circuit, Vext is the power supply terminal, Vout is the output terminal, GND is ground, R1 and R2 are voltage divider resistors, R3 is a pull-up resistor, R4 is a pull-down resistor, Q1 is an NPN transistor, M1 is an N-channel MOSFET, and D1 and D2 are input diodes. The base, collector, and emitter on the transistor are the base, collector, and emitter, respectively; the gate, drain, and source on the MOSFET are the gate, drain, and source, respectively.

[0079] The function of D1 is to prevent the power supply of the redundant braking control circuit from being reversed and to prevent the energy storage element from discharging to the outside through Vest.

[0080] The function of C1 is to store energy and enable output during power outages.

[0081] The function of Q1 is to control the gate of the MOSFET;

[0082] The function of R1 and R2 is to divide the voltage and drive the base of the transistor.

[0083] The function of R3 is to pull up the gate G when the transistor is not conducting.

[0084] The function of R4 is to pull down the source S;

[0085] D2: Ensures unidirectional output of redundant braking control circuit;

[0086] The redundant braking control circuit is specifically connected as follows: the P-terminal of diode D1 is connected to Vext, and the N-terminal is connected to capacitor C1, resistor R3, and the drain of the MOSFET; one end of C1 is connected to the N-terminal of diode D1, resistor R3, and the drain of MOSFET M1, and the other end is connected to GND; one end of R1 is connected to the P-terminal of diode D1, and the other end is connected to the base of transistor Q1; one end of R3 is connected to the N-terminal of D1, capacitor C1, and the drain of the MOSFET, and the other end is connected to the collector of transistor Q1 and the gate of MOSFET M1; the drain of MOSFET M1 is connected to the N-terminal of D1, resistor R3, and capacitor C1; the gate of MOSFET M1 is connected to resistor R3 and the collector of transistor Q1; the source (S) terminal of MOSFET M1 is connected to resistor R4 and the P-terminal of diode D2; the collector of transistor Q1 is connected to resistor R3 and the gate of MOSFET M1. The base (b) of transistor Q1 is connected to resistors R2 and R1, and the emitter (e) of transistor Q1 is connected to ground and resistors R2 and R4. The point (p) of diode D2 is connected to resistor R4 and the source (s) of MOSFET M1, and the neutral (n) of diode D2 is connected to Vout. One end of R2 is connected to the base (b) of transistor Q1 and R1, and the other end is connected to the emitter (e) of transistor Q1, R4, and GND. One end of R2 is connected to the point (p) of diode D2 and the source (s) of MOSFET M1, and the other end is connected to the emitter (e) of transistor Q1, R2, and GND.

[0087] The power supply method for the redundant braking control circuit is as follows: (See details below) Figure 3 Powered by battery Vbat;

[0088] With a 12V supply voltage, a suitable component selection for this function is as follows: D1 and D2 are 1N4007, C1 is a 0.05F / 16V electrolytic capacitor, Q1 is a 2N3904, R1=15KΩ, R2=6.8KΩ, R3=10KΩ, R4=1KΩ, and the MOSFET is an IRLZ44N.

[0089] The working method of the redundant braking control circuit is as follows: When there is a voltage in Vest, Vest powers the energy storage element C1. At the same time, it acts as a voltage divider for R1 and R2, and the b point is at a high level, causing the transistor to conduct. At this time, G is pulled low, causing the MOS to turn off. Vout outputs a low level due to the pull-down of R4.

[0090] When there is no voltage at Vest, b is at a low level. At this time, c and e are not conducting. Since the current flowing into G is very small (this needs to be designed separately), G is still at a high level. At this time, MOS is conducting, that is, the drain and source of MOS transistor are conducting, and the voltage at C1 is output through Vout.

[0091] The redundant controller also includes an MCU, the principle of which is as follows: Figure 2 As shown in the figure, the redundant braking circuit is as follows: Figure 1 The base, collector, and emitter of the transistor are b, c, and e, respectively; the power supply terminal of the MCU is Vbat, and the MCU is connected to an external communication network. The MCU switches the redundant braking circuit operating condition by controlling the MCU pin connected to the base of the transistor to be high or low.

[0092] When the base of the transistor is connected to a low level, the collector and emitter of the transistor are disconnected, and the redundant braking circuit is de-energized. When the base of the transistor is connected to a high level, the collector and emitter of the transistor are connected, and the output Vout of the redundant braking circuit is connected to the collector (c) of the two-position three-way valve.

[0093] In step three, when the system is powered off, the redundant controller automatically energizes the c-end of the two-position three-way valve, causing the solenoid valve state of the two-position three-way valve to switch to the braking state.

[0094] When the redundant braking controller determines that the main braking controller is abnormal, the control MCU outputs a low level at the b pin of the transistor. At this time, there is no voltage input to Vext, which switches the state of the solenoid valve of the two-position three-way valve to the state that requires braking.

[0095] In the braking system, the brake wheel cylinder has two braking modes: the service brake wheel cylinder mode, which brakes when air is supplied to the brake wheel cylinder, and the parking brake wheel cylinder mode, which brakes when no air is supplied to the brake wheel cylinder.

[0096] The two-position three-way valve adopts a slide valve structure and does not have a return spring;

[0097] In the parking brake wheel cylinder method, the power-off braking requires controlling the exhaust of the brake wheel cylinder when the power is off. In the settings of state B and state A of its two-position three-way valve, when state B, i.e., when the c end is energized, the exhaust end is connected to the brake wheel cylinder and the air supply end is cut off. When state A, i.e., when the a end is energized, the air supply end is connected to the brake wheel cylinder and the exhaust end is cut off.

[0098] In the parking brake wheel cylinder system, one example of a two-position three-way valve is: Figure 4 As shown, when the coil controlled by end a is energized, the slide valve moves to the left (the solenoid valve is in the state shown in the right square diagram). Ends b and c each have a set of coils, making ends b and c electrically independent. Controlling end b will not affect the circuit of end c, and controlling end c will not affect the circuit of end b. Both can control the slide valve to move to the right (the solenoid valve is in the state shown in the left square diagram), achieving the required function. Under the condition that b and c are electrically independent, the D2 diode in the redundant braking control circuit is unnecessary. Another implementation method is that b and c are not electrically independent, such as... Figure 5As shown, b and c are two terminals connected to the same coil. The valve works on the same principle, but the D2 diode in the redundant braking control circuit needs to be equipped.

[0099] In the service brake wheel cylinder system, the valve core needs to be swapped between left and right during the production of the two-position three-way valve, such as... Figure 4 As shown, to be compatible with the braking system, that is: if power-off braking is required, the air intake of the brake wheel cylinder needs to be controlled when power is off. In the settings of state B and state A of the two-position three-way valve, state B is when the c end is energized, the air supply end is connected to the brake wheel cylinder and the exhaust end is cut off. State A is when the a end is energized, the exhaust end is connected to the brake wheel cylinder and the air supply end is cut off.

[0100] In the service brake wheel cylinder system, one example of a two-position three-way valve is: Figure 6 As shown, when the coil controlled by end a is energized, the slide valve moves to the left (the solenoid valve is in the state shown in the right square diagram); when end b is energized, the slide valve moves to the right (the solenoid valve is in the state shown in the left square diagram). The method of setting b and c to share a single coil is as follows: Figure 5 As shown.

[0101] In this example, the braking system is based on a series dual-chamber caliper for braking, with the brake wheel cylinder driving the caliper to perform the vehicle's braking task.

[0102] In this example, the output Vout of the redundant braking circuit is connected to terminal c of the two-position three-way solenoid valve; the voltage divider resistors R1 and R2 should be set to be greater than the voltage Vb required for Q1 to conduct, i.e. .

Claims

1. A redundant braking system control circuit and a system for automatic braking upon power failure, characterized in that: The system is a braking system that performs braking through a two-way valve system with memory function, and uses a redundant braking control circuit to perform redundant braking control on the two-way valve system, so that it has the ability to automatically brake when power is off. The bidirectional valve system includes a solenoid valve for braking, and also includes a main brake controller and a redundant brake controller connected to the solenoid valve. The control method for redundant braking includes the following steps; Step 1: The main brake controller and the redundant brake controller determine each other's operating conditions via the communication network. Step 2: The main brake controller controls the solenoid valve according to the braking demand to avoid malfunction of the solenoid valve caused by abnormal power failure of the redundant brake controller. Step 3: The redundant controller determines whether braking is needed based on the power supply status of the braking system and the operating status of the main brake controller, and controls the solenoid valve when braking is needed. The braking system is used for vehicle braking. The main brake controller is used for the normal operating condition of the two-way valve system, and the redundant brake controller is used for the abnormal operating condition of the two-way valve system. Both the main brake controller and the redundant brake controller are connected to the communication network. The solenoid valve is a two-position three-way valve including terminals a, b, and c. In the two-way valve system, the power supply terminal of the main brake controller includes a power supply and a ground terminal. The power supply terminal is connected to the battery, and terminals a and b are used to control the state switching of the two-position three-way valve. The two-position three-way valve has two operating conditions: state A and state B, which are respectively: the air supply end of the vehicle braking mechanism is connected to the brake wheel cylinder and the exhaust end is cut off; and the exhaust end of the vehicle braking mechanism is connected to the brake wheel cylinder and the air supply end is cut off. The terminals b and c of the two-position three-way valve are used to control state B, and the terminal a of the two-position three-way valve is used to control state A. That is, when terminal a is energized, the two-position three-way valve operates in state A, and when terminal b is energized, the two-position three-way valve operates in state B. In step two, if the main brake controller does not require braking, it intermittently controls the solenoid valve a terminal of the two-way valve system to be energized to prevent the solenoid valve from being in a braking state due to abnormal power failure of the redundant brake controller. If the main brake controller needs to brake, or receives a command to brake, it will energize the b end of the control solenoid valve, causing the solenoid valve to switch to the braking state. The redundant braking controller includes a redundant braking control circuit, which includes a storage element C1 and an external circuit. When there is voltage at the Vext terminal of the redundant braking control circuit, the external circuit charges the storage element, and at this time there is no voltage at the Vout terminal of the redundant braking control circuit. When there is no voltage at the Vext terminal, the external circuit outputs the electrical energy in the storage element and outputs voltage at the Vout terminal to change the state of the solenoid valve. The energy storage capacity of the energy storage element C1 is at least sufficient to meet the energy required to change the primary state of the solenoid valve. Assume the load current is... The power-on time is The minimum operating voltage of the solenoid valve is The energy storage capacity of the energy storage element can be expressed by the formula: ， In the formula It is the external input voltage. It is the voltage drop across the diode.

2. The redundant braking system control circuit and the automatic braking system upon power failure according to claim 1, characterized in that: In step one, the main brake controller sends a unique broadcast signal with predetermined characteristics to the communication network connected to it, so that the redundant controller can determine whether the main brake controller is normal based on the communication network; when the broadcast signal is not present, or the broadcast signal is abnormal, or the main controller actively broadcasts a fault code, the redundant controller determines that the main brake is abnormal. Similarly, the redundant brake controller also sends a unique broadcast signal with predetermined characteristics to the communication network connected to it, so that the main brake controller can determine whether the redundant brake controller is normal based on the communication network; when the broadcast signal is not present, or the broadcast signal is abnormal, or the redundant controller actively broadcasts a fault code, the main brake controller determines that the redundant brake controller is abnormal.

3. The redundant braking system control circuit and the automatic braking system upon power failure according to claim 2, characterized in that: The broadcast signals sent by the main brake controller and the redundant brake controller are characterized by being sent at predetermined intervals, and the values ​​of the broadcast signals change cyclically.

4. The redundant braking system control circuit and the automatic braking system upon power failure according to claim 1, characterized in that: The energy storage element is a capacitor or a battery; In the redundant braking control circuit, Vext is the power supply terminal, Vout is the output terminal, GND is ground, R1 and R2 are voltage divider resistors, R3 is a pull-up resistor, R4 is a pull-down resistor, Q1 is an NPN transistor, M1 is an N-channel MOSFET, and D1 and D2 are input diodes. The base, collector, and emitter of the transistor are the base, collector, and emitter, respectively; the gate, drain, and source of the MOSFET are the gate, drain, and source, respectively. The function of D1 is to prevent the power supply of the redundant braking control circuit from being reversed and to prevent the energy storage element from discharging to the outside through Vest. The function of C1 is to store energy and to enable output during power outages. The function of Q1 is to control the gate of the MOSFET; The function of R1 and R2 is to divide the voltage and drive the base of the transistor. The function of R3 is to pull up the gate G when the transistor is not conducting. The function of R4 is to pull down the source S; D2: Ensures unidirectional output of redundant braking control circuit; The redundant braking control circuit is specifically connected as follows: the P-terminal of diode D1 is connected to Vext, and the N-terminal is connected to capacitor C1, resistor R3, and the drain of the MOSFET; one end of C1 is connected to the N-terminal of diode D1, resistor R3, and the drain of MOSFET M1, and the other end is connected to GND; one end of R1 is connected to the P-terminal of diode D1, and the other end is connected to the base of transistor Q1; one end of R3 is connected to the N-terminal of D1, capacitor C1, and the drain of the MOSFET, and the other end is connected to the collector of transistor Q1 and the gate of MOSFET M1; the drain of MOSFET M1 is connected to the N-terminal of D1, resistor R3, and capacitor C1; the gate of MOSFET M1 is connected to resistor R3 and the collector of transistor Q1; the source (S) terminal of MOSFET M1 is connected to resistor R4 and the P-terminal of diode D2; the collector of transistor Q1 is connected to resistor R3 and the gate of MOSFET M1. The base (b) of transistor Q1 is connected to resistors R2 and R1, and the emitter (e) of transistor Q1 is connected to ground and resistors R2 and R4. The point (p) of diode D2 is connected to resistor R4 and the source (s) of MOSFET M1, and the neutral (n) of diode D2 is connected to Vout. One end of R2 is connected to the base (b) of transistor Q1 and R1, and the other end is connected to the emitter (e) of transistor Q1, R4, and GND. One end of R2 is connected to the point (p) of diode D2 and the source (s) of MOSFET M1, and the other end is connected to the emitter (e) of transistor Q1, R2, and GND. The redundant braking control circuit is powered by battery Vbat; The working method of the redundant braking control circuit is as follows: When there is a voltage in Vest, Vest powers the energy storage element C1. At the same time, it acts as a voltage divider for R1 and R2, and the b point is at a high level, causing the transistor to conduct. At this time, G is pulled low, causing the MOS to turn off. Vout outputs a low level due to the pull-down of R4. When there is no voltage at Vest, b is at a low level, c and e are not conducting, G is at a high level, MOS is conducting, that is, the drain and source of the MOS transistor are conducting, and the voltage at C1 is output through Vout. The redundant controller also includes an MCU. The MCU is powered by Vbat. The MCU switches the redundant braking circuit operating conditions by controlling the MCU pin connected to the base of the transistor to be high or low. When the MCU pin connected to the base of the transistor is at a low level, the collector and emitter of the transistor are disconnected, and the redundant braking circuit is de-energized. When the MCU pin connected to the base of the transistor is at a high level, the collector and emitter of the transistor are connected, and the output Vout of the redundant braking circuit is connected to the collector (C) terminal of the two-position three-way valve.

5. The redundant braking system control circuit and the automatic braking system upon power failure according to claim 4, characterized in that: In step three, when the system is powered off, the redundant controller automatically energizes the c-end of the two-position three-way valve, causing the solenoid valve state of the two-position three-way valve to switch to the braking state. When the redundant braking controller determines that the main braking controller is abnormal, the control MCU outputs a low level at the b pin of the transistor. At this time, there is no voltage input to Vext, which switches the state of the solenoid valve of the two-position three-way valve to the state that requires braking. In the braking system, the brake wheel cylinder has two braking modes: the service brake wheel cylinder mode, which brakes when air is supplied to the brake wheel cylinder, and the parking brake wheel cylinder mode, which brakes when no air is supplied to the brake wheel cylinder.

6. The redundant braking system control circuit and the automatic braking system upon power failure according to claim 5, characterized in that: The two-position three-way valve includes a slide valve structure and does not have a return spring; In the parking brake wheel cylinder method, the power-off braking requires controlling the exhaust of the brake wheel cylinder when the power is off. In the settings of state B and state A of its two-position three-way valve, when state B, i.e., when the c end is energized, the exhaust end is connected to the brake wheel cylinder and the air supply end is cut off. When state A, i.e., when the a end is energized, the air supply end is connected to the brake wheel cylinder and the exhaust end is cut off. In the service brake wheel cylinder mode, when the power is cut off, the brake wheel cylinder needs to be controlled to receive air. In the settings of state B and state A of the two-position three-way valve, state B is when the c end is energized, the air supply end is connected to the brake wheel cylinder and the exhaust end is cut off. State A is when the a end is energized, the exhaust end is connected to the brake wheel cylinder and the air supply end is cut off.

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