A commercial vehicle brake system control device

Abstract

The application relates to vehicle braking technology and discloses a commercial vehicle braking system control device which comprises an electromagnetic valve driving chip power supply module, an MCU main control module, a power supply chip power supply module and a braking electromagnetic valve unit; the power supply chip power supply module provides power supply to the MCU main control module, the MCU main control module transmits a control signal PWR_Vavle_ctr to the electromagnetic valve driving chip power supply module, and the electromagnetic valve driving chip power supply module provides power supply to the braking electromagnetic valve unit. The braking system control device designed by the application adopts a hardware voltage reduction and stabilization mode, the power supply chip can adopt a power supply chip with a maximum voltage resistance value of 45V and a lower cost, the shutdown mode includes hardware shutdown or software shutdown, and the electromagnetic valve driving chip can adopt an electromagnetic valve driving chip with a maximum voltage resistance value of 60V and a lower cost.

Description

Technical Field

[0001] This invention relates to vehicle braking technology, and more particularly to a control device for a commercial vehicle braking system. Background Technology

[0002] With the development of vehicle technology, vehicle braking has evolved from using a vacuum booster to power the master cylinder to a brake motor powering the master cylinder. The electronic control module housing the brake motor is powered by the vehicle battery. Due to the complex operating environment of automobiles, onboard electrical components are constantly subjected to high-voltage pulses. Without corresponding and effective protection mechanisms, these modules are highly susceptible to damage, leading to malfunctions and endangering the lives and property of pedestrians and drivers.

[0003] The existing technology CN202211081059.9, in the test of the "Load Drop" item in Section 4.6.4 "Transient Changes in Supply Voltage" of "GB / T28046.2-2019 Environmental Conditions and Tests for Electrical and Electronic Equipment of Road Vehicles Part 2: Electrical Loads", has a relatively late turn-off time, which poses a risk that the high voltage will affect other components. Summary of the Invention

[0004] This invention addresses the problem in the prior art where the turn-off time is relatively late in the "Load Drop" test of Section 4.6.4 "Transient Changes in Supply Voltage" of "GB / T28046.2-2019 Environmental Conditions and Tests for Electrical and Electronic Equipment of Road Vehicles Part 2: Electrical Loads", which poses a risk of high voltage affecting other components. This invention provides a control device for the braking system of a commercial vehicle.

[0005] To solve the above-mentioned technical problems, the present invention provides the following technical solution: A control device for a commercial vehicle braking system includes a solenoid valve drive chip power supply module, an MCU main control module, a power chip power supply module, and a braking solenoid valve unit. The power chip power supply module provides power to the MCU main control module, the MCU main control module transmits control signal PWR_Vavle_ctr to the solenoid valve drive chip power supply module, and the solenoid valve drive chip power supply module provides power to the braking solenoid valve unit.

[0006] Preferably, the power supply module for the solenoid valve drive chip includes a first shutdown unit, a second shutdown unit, and a main control switch unit; the input signal of the first shutdown unit is the control signal transmitted by the MCU main control module; the first shutdown unit and the second shutdown unit are connected in parallel, and the output terminals of the first shutdown unit and the second shutdown unit are both connected to the main control switch unit; the output terminal of the main control switch unit is connected to the solenoid valve unit.

[0007] Preferably, the second shutdown unit includes a Zener diode Z2; one end of the Zener diode Z2 is connected to the input ignition power supply Ign+, and the other end of the Zener diode Z2 is connected to resistors R7 and R8; the other end of resistor R7 is grounded, and the other end of resistor R8 is connected to resistor R9 and Zener diode Z3; the other end of Zener diode Z3 is grounded, and the other end of resistor R9 is connected to the gate of MOSFET Q2; the source of MOSFET Q2 is grounded, and the drain of MOSFET Q2 is connected to the main control switch unit.

[0008] Preferably, the main control switch unit includes a diode D2, one end of which is connected to the input terminal bat+; the other end of the diode D2 is connected to a relay K1; the relay K1 is connected to a transistor T2; and the relay K1 is connected to the solenoid valve unit.

[0009] Preferably, the power supply module of the power chip includes a diode D1, one end of which is connected to the input ignition power supply Ign+; the other end of the diode D1 is connected to a resistor R3 and the drain of a MOSFET Q1, the other end of the resistor R3 and the gate of the MOSFET Q1 are connected to a Zener diode Z1, the other end of the Zener diode Z1 is grounded, and the source of the MOSFET Q1 is connected to the power chip and the MCU main control module.

[0010] Preferably, a current-limiting resistor R5 is connected between the first shutdown unit and the main control unit.

[0011] Preferably, MOSFET Q2 is an NMOS transistor.

[0012] Preferably, Zener diodes Z1, Z2, and Z3 are all low-voltage cutoff diodes.

[0013] Preferably, the MCU main control module transmits the control signal PWR_Vavle_ctr in the following ways: The MCU main control module acquires the voltage value V0, calculates the voltage value V1, and measures the voltage value Va. The main control signal PWR_Vavle_ctr is determined by acquiring the voltage value V0 and calculating the voltage value V1 by the MCU main control module. When the voltage value V0 acquired by the MCU main control module and the voltage value V1 calculated by the MCU main control module are within the set threshold range, the main control signal PWR_Vavle_ctr is high; otherwise, the main control signal PWR_Vavle_ctr is low.

[0014] Preferably, the MCU main control module calculates the voltage value V1 by continuously sampling the voltage of N data points, removing the maximum value Vmax and the minimum value Vmin, and then calculating the arithmetic mean voltage of the remaining N-2 data points to obtain the voltage value V1.

[0015] This invention, by adopting the above technical solutions, has significant technical effects: This invention uses a hardware step-down and voltage-regulating method, and the power supply chip can be a low-cost power supply chip with a maximum withstand voltage of 45V.

[0016] The shutdown method of the present invention includes hardware shutdown or software shutdown, in which case the solenoid valve driver chip can be a low-cost solenoid valve driver chip with a maximum withstand voltage of 60V.

[0017] This invention avoids overvoltage of the power supply chip in the braking system, which could damage the control core MCU of the braking system; and avoids overvoltage damage of the solenoid valve drive chip in the actuator of the braking system, which could lead to braking failure. Attached Figure Description

[0018] Figure 1 This is a circuit diagram of the present invention.

[0019] Figure 2 This is a circuit diagram of existing technology.

[0020] Figure 3 This is the pulse maximum voltage test diagram of the present invention.

[0021] Figure 4 This is a flowchart of the main control signal generation process of the present invention. Detailed Implementation

[0022] The present invention will now be described in further detail with reference to the accompanying drawings and embodiments.

[0023] Example 1 exist Figure 2 The device in question is a control unit for a commercial vehicle braking system. When conducting the "Load Drop" test in Section 4.6.4, "Transient Changes in Supply Voltage," of GB / T 28046.2-2019 "Environmental Conditions and Tests for Electrical and Electronic Equipment of Road Vehicles - Part 2: Electrical Loads," the relatively late turn-off time poses a risk of high voltage affecting other components. Furthermore, its main control unit requires control through several switching transistors.

[0024] Example 2 A control device for the braking system of a commercial vehicle. Figure 1 The system includes a solenoid valve drive chip power supply module, an MCU main control module, a power chip power supply module, and a braking solenoid valve unit. The power chip power supply module provides power to the MCU main control module, the MCU main control module transmits the control signal PWR_Vavle_ctr to the solenoid valve drive chip power supply module, and the solenoid valve drive chip power supply module provides power to the braking solenoid valve unit.

[0025] The solenoid valve drive chip power supply module includes a first shutdown unit, a second shutdown unit, and a main control switch unit. The input signal of the first shutdown unit is the control signal transmitted by the MCU main control module. The first shutdown unit and the second shutdown unit are connected in parallel. The output terminals of the first shutdown unit and the second shutdown unit are both connected to the main control switch unit. The output terminal of the main control switch unit is connected to the solenoid valve unit.

[0026] The second shutdown unit includes a Zener diode Z2; one end of the Zener diode Z2 is connected to the input ignition power supply Ign+, and the other end of the Zener diode Z2 is connected to resistors R7 and R8; the other end of resistor R7 is grounded, and the other end of resistor R8 is connected to resistor R9 and Zener diode Z3; the other end of Zener diode Z3 is grounded, and the other end of resistor R9 is connected to the gate of MOSFET Q2; the source of MOSFET Q2 is grounded, and the drain of MOSFET Q2 is connected to the main control switch unit.

[0027] The main control switch unit includes diode D2, one end of which is connected to the input terminal bat+; the other end of diode D2 is connected to relay K1; relay K1 is connected to transistor T2; relay K1 is connected to the solenoid valve unit.

[0028] The power supply module includes diode D1. One end of diode D1 is connected to the input ignition power supply Ign+. The other end of diode D1 is connected to resistor R3 and the drain of MOSFET Q1. The other end of resistor R3 and the gate of MOSFET Q1 are connected to Zener diode Z1. The other end of Zener diode Z1 is grounded. The source of MOSFET Q1 connects to the power supply module and the MCU main control module. Zener diode Z1 is a low-voltage cutoff diode.

[0029] The power supply module "Ign+" provides the ignition voltage signal for the entire vehicle. D1 is a reverse polarity protection diode. The NMOS transistor Q1, resistor R3, and Zener diode Z1 form a step-down voltage regulator circuit. Assume the gate threshold voltage of the NMOS transistor Q1... The VGS(th) value is 2.5V, the forward voltage drop of diode D1 is 0.7V, the voltage regulation value of Zener diode Z1 is 33V, the vehicle system is a 24V system, and its normal operating voltage is 18V~32V. When the vehicle's operating voltage is 18V, the input voltage of the power supply chip is 14.8V; When the transient operating voltage of the vehicle is 43V, the input voltage of the power supply chip is 31.5V; Resistors R1 and R2, and capacitor C1 constitute the vehicle power supply voltage acquisition circuit. Resistors R1 and R2 are voltage divider resistors, and capacitor C1 is a filter capacitor.

[0030] Bat+ is the battery voltage signal supplying power to the entire vehicle. Diode D2 is a reverse polarity protection diode. K1 is a relay. Diode D2 is a freewheeling diode. Capacitor C2 is a filter capacitor; it filters out high-frequency signals and also provides a delay for sudden voltage changes. Resistor R5 is a current-limiting resistor, resistor R6 is a voltage divider resistor, and NPN transistor T2 drives relay K1.

[0031] The second shutdown unit is a high-voltage hardware shutdown circuit. When the output of the high-voltage hardware shutdown circuit is in a high-impedance state, if PWR_Vavle_ctr=1, transistor T2 is turned on, the relay coil is energized, pins 3 and 5 of relay K1 are turned on, and solenoid valve driver chips U5, U6 and U7 are energized.

[0032] In the high-voltage hardware shutdown circuit, Zener diode Z1 is a low-voltage cutoff diode. The low voltage cannot pass through Z1 and then through resistors R8 and R9 to act on the gate of NMOS transistor Q2. Resistors R7 and R8 are voltage divider resistors, and resistor R9 is a current-limiting resistor. Zener diode Z3 is used to ensure that the voltage between the gate and source of NMOS transistor Q2 does not exceed its withstand voltage. Assuming that the gate threshold voltage VGS(th) of NMOS transistor Q2 is 2.5V and the Zener voltage of Zener diode Z1 is 30V, when the vehicle power supply voltage is greater than 32.5V, the drain and source of Q2 conduct, pulling the "LOW" point down to 0V, that is, the base voltage of transistor T2 is 0V. At this time, regardless of whether the output of "PWR_Vavle_ctr" is 1 or 0, transistor T2 will be cut off, the coil of relay K1 is de-energized, pins 3 and 5 of relay K1 are disconnected, and the solenoid valve driver chips U5, U6, and U7 are de-energized. When the vehicle power supply voltage is less than 32.5V, the NMOS transistor Q2 outputs a high-impedance state.

[0033] Example 3 Based on Example 2, commercial vehicles currently use a 24V system as the standard. The alternator pulse parameters for load dump suppression are provided by the OEM based on their own alternators, either through calculation or actual testing. Figure 3 In the 24V power supply system test, US is 178V, UA is 28V, and tr is 8ms; where UA is the test voltage when the generator is supplying power; US is the highest pulse voltage, tr is the pulse rise time; and td is the pulse duration. The highest pulse voltage US and the pulse rise time tr are the main parameters of interest.

[0034] 0.9(US-UA)+UA=0.9(178-28)+28=163V; 0.1(US-UA)+UA=0.1(178-28)+28=43V; As can be seen from the experimental pulse waveform, it only takes 8ms for the voltage to rise from 43V to 163V.

[0035] In the automotive electronics field, power supply chips commonly used in 24V systems have maximum withstand voltages of 45V and 60V. In recent years, with the introduction of 48V systems in vehicles, power supply chips with a maximum withstand voltage of 80V have become more common. Generally, with other parameters being equal, a lower maximum withstand voltage usually corresponds to lower cost. Similarly, solenoid valve driver chips commonly used in 24V systems in the automotive electronics field have maximum withstand voltages of 60V and 80V. Again, a lower maximum withstand voltage usually corresponds to lower cost. For hardware-based voltage reduction and regulation, a lower-cost power supply chip with a maximum withstand voltage of 45V can be used. For hardware and software shutdown methods, a lower-cost solenoid valve driver chip with a maximum withstand voltage of 60V can be used.

[0036] A commonly used anti-pulse interference averaging filter is selected. The anti-pulse interference averaging filter samples N data points consecutively (N is typically 3~14), removes the maximum and minimum values, and calculates the arithmetic mean of the remaining N-2 data points. This averaging filter calculation method combines the anti-interference capability of median filtering with the smoothing properties of arithmetic averaging.

[0037] The experimental pulse waveform shows that the voltage rises from 43V to 163V in just 8ms. The solenoid valve driver chip only needs about 1ms to rise from 43V to 60V. The voltage signal is periodically acquired within a 0.25ms timer interrupt. If braking is in progress (i.e., the braking valid command flag is 1), an anti-pulse interference averaging filter program is executed (N=3). The voltage value is calculated; if it exceeds the threshold, the main power supply to all solenoid valves is shut off; otherwise, the process returns. If there is no braking command (i.e., the braking valid command flag is 0), the anti-pulse interference averaging filter program is not executed, and the real-time acquired voltage value is used directly. If the voltage exceeds the threshold, the main power supply to all solenoid valves is shut off; otherwise, the process returns. This effectively optimizes the real-time limitation problem and reduces resource consumption.

[0038] Example 4 Based on the above embodiments, for Figure 4At the start of the 0.25ms interrupt routine, the MCU main control module acquires the voltage V0 at the AD0 port and then checks the valid command flag. When the valid command flag is high, the anti-pulse interference averaging filter program is executed to calculate the voltage value V1, and the actual measured voltage value Va of the MCU main control module is the calculated voltage value V1; otherwise, the actual measured voltage value Va of the MCU main control module is the voltage V0 at the AD0 port. The measured voltage value Va of the MCU main control module is then checked. If the measured voltage value Va is between the maximum voltage value Vmax and the minimum voltage value Vmin, then PWR_Vavle_ctr is high; otherwise, PWR_Vavle_ctr is low. If PWR_Vavle_ctr=1, transistor T2 conducts, the relay coil is energized, pins 3 and 5 of relay K1 conduct, and solenoid valve driver chips U5, U6, and U7 are energized.

Claims

1. A control device for a commercial vehicle braking system, comprising a solenoid valve drive chip power supply module, an MCU main control module, a power chip power supply module, and a braking solenoid valve unit; characterized in that, The power supply module provides power to the MCU main control module. The MCU main control module transmits the control signal PWR_Vavle_ctr to the solenoid valve driver chip power supply module, which in turn provides power to the braking solenoid valve unit. The solenoid valve driver chip power supply module includes a first shutdown unit, a second shutdown unit, and a main control switch unit. The input signal of the first shutdown unit is the control signal transmitted by the MCU main control module. The first shutdown unit and the second shutdown unit are connected in parallel, and the output terminals of both units are connected to the main control switch unit. The output terminal of the main control switch unit is connected to the solenoid valve unit. The second shutdown unit includes a Zener diode Z2. One end of the Zener diode Z2 is connected to the input ignition power supply Ign+, and the other end is connected to resistors R7 and R8. The other end of resistor R7 is grounded, and resistor R8... The other end of 8 is connected to resistor R9 and Zener diode Z3; the other end of Zener diode Z3 is grounded, and the other end of resistor R9 is connected to the gate of MOSFET Q2; the source of MOSFET Q2 is grounded, and the drain of MOSFET Q2 is connected to the main control switch unit; the main control switch unit includes diode D2, one end of which is connected to the input terminal bat+; the other end of diode D2 is connected to relay K1; relay K1 is connected to transistor T2; relay K1 is connected to the solenoid valve unit; the power supply module of the power chip includes diode D1, one end of which is connected to the input ignition power Ign+; the other end of diode D1 is connected to resistor R3 and the drain of MOSFET Q1, the other end of resistor R3 and the gate of MOSFET Q1 are connected to Zener diode Z1, the other end of Zener diode Z1 is grounded, and the source of MOSFET Q1 is connected to the power chip and the MCU main control module.

2. The commercial vehicle braking system control device according to claim 1, characterized in that, A current-limiting resistor R5 is connected between the first shutdown unit and the main control unit.

3. The commercial vehicle braking system control device according to claim 1, characterized in that, MOSFET Q2 is an NMOS transistor.

4. The commercial vehicle braking system control device according to claim 1, characterized in that, Zener diodes Z2 and Z3 are both low-voltage cutoff diodes.

5. A commercial vehicle braking system control device according to claim 1, characterized in that, The MCU main control module transmits the control signal PWR_Vavle_ctr in the following ways: The MCU main control module acquires the voltage value as V0; The MCU main control module calculates the voltage value as V1; The main control signal PWR_Vavle_ctr is determined by acquiring the voltage value V0 and calculating the voltage value V1 by the MCU main control module. When the voltage value V0 acquired by the MCU main control module and the voltage value V1 calculated by the MCU main control module are within the set threshold range, the main control signal PWR_Vavle_ctr is high; otherwise, the main control signal PWR_Vavle_ctr is low.

6. A commercial vehicle braking system control device according to claim 5, characterized in that, The voltage value V1 of the MCU main control module is calculated by continuously sampling the voltage of N data points, removing the maximum and minimum values, and then calculating the arithmetic mean voltage of the remaining N-2 data points to obtain the voltage value V1.

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