An automatic fail-safe automobile wiper and light control circuit

Abstract

The application provides an automatic anti-failure automobile wiper and light control circuit, which has a power supply interface, a signal input interface and a function output interface. The control circuit comprises a signal generation module, a control unit, a driving module, an execution module and a hardware backup control module. The control unit is connected to the execution module through the driving module, receives the switch signal sent by the signal generation module through the signal input interface and outputs a control signal. The execution module is connected to the function output interface and performs a control action according to the control signal to control the on-off of the controlled device connected to the function output interface. The hardware backup control module is connected to the signal generation module and the execution module. When the switch signal is at a low level and the control unit is in a failure state, the hardware backup control module directly controls the execution module. The application solves the technical problem that the traditional watchdog scheme has a response delay after the MCU fails, which may cause the interruption of the wiper or light function and thus cause a safety hazard.

Description

Technical Field

[0001] This invention relates to the field of automotive electronic control technology, and more specifically, to a control circuit for an automatic anti-failure automotive windshield wiper and lights. Background Technology

[0002] With the development of automotive electronics technology, wiper and lighting control functions have become increasingly complex. Automatic wipers, speed-adjustable wipers, and automatic headlights have become mainstream features. The realization of these complex functions relies on the precise control of a microcontroller (MCU), which has led to the gradual replacement of traditional simple switch-controlled wiper and lighting systems by body controllers or other controllers with integrated MCUs. However, MCUs may fail in hardware or software in complex vehicle operating environments. Once the MCU fails, the wiper and lighting functions will be lost.

[0003] To address this issue, wiper and headlight control functions typically incorporate hardware designs to prevent MCU failure, thus ensuring that the wiper or headlight functions do not fail when the MCU fails. In traditional wiper and headlight control circuits, the failure prevention design is usually implemented using a hardware watchdog timer and a hardware control circuit. When the hardware watchdog timer detects an MCU failure, it enables the hardware circuit to bypass the MCU and directly control the wiper and headlight functions.

[0004] However, the relevant technology has at least one of the following problems: Traditional watchdog solutions work based on the principle of timer overflow. After the MCU fails, it needs to wait for the timer to overflow before it can output a trigger signal. There is usually a response delay of hundreds of milliseconds. During this period, the wiper or headlight functions are interrupted. In particular, the brief blackout of the headlights at night may cause strong interference to the driver and cause safety hazards. Summary of the Invention

[0005] This invention solves the technical problem that traditional watchdog solutions suffer from response delays when the MCU fails, which can cause wiper or headlight malfunctions to be interrupted, thus posing a safety hazard.

[0006] To address the aforementioned problems, this invention provides an automatic anti-failure control circuit for automotive windshield wipers and lights. The control circuit includes a power interface, a signal input interface, and a function output interface. It comprises a signal generation module, a control unit, a drive module, an execution module, and a hardware backup control module. The control unit is connected to the execution module via the drive module, receives a switch signal from the signal generation module via the signal input interface, and outputs a control signal. The execution module is connected to the function output interface and performs control actions according to the control signals to control the on / off state of the controlled devices connected to the function output interface. The hardware backup control module connects the signal generation module and the execution module. When the switch signal is low and the control unit is in a failure state, the hardware backup control module directly controls the execution module.

[0007] Compared with existing technologies, the technical effects achieved by this solution are as follows: before the switching signal is acquired by the hardware circuit, it is directly connected to the coil control terminal of the corresponding execution module through a hardware backup control module. This allows the vehicle to automatically implement the required control functions when the control unit fails, achieving zero-delay takeover of the vehicle's required functions and improving control continuity. At the same time, there is no need to configure an additional watchdog chip and dedicated power supply, which simplifies the control circuit structure, reduces the number of components, and lowers production costs and failure risks.

[0008] In one embodiment of the present invention, the signal generation module includes: a plurality of functional switches; the execution module includes: a plurality of relays corresponding to the functional switches; the hardware backup control module includes: a plurality of backup diodes corresponding to the functional switches, wherein the cathode of the backup diode is connected to the switch output terminal of the corresponding functional switch, and the anode of the backup diode is connected to the coil control terminal of the corresponding relay.

[0009] Compared with existing technologies, the technical effects achieved by this solution are as follows: Multiple function switches in the signal generation module correspond one-to-one with multiple relays in the execution module, and the backup diodes in the hardware backup control module also correspond one-to-one with the function switches, forming a precise one-to-one control relationship, avoiding signal interference between different functions, and improving control accuracy; the backup diodes adopt a connection method of "cathode connected to the function switch output terminal and anode connected to the relay coil control terminal," utilizing the unidirectional conduction characteristic of the diode to achieve unidirectional transmission of the switch signal to the relay, preventing signal backflow, protecting the function switch and relay coil, and improving circuit stability; the backup diodes simplify the hardware backup control path structure, eliminating the need for complex auxiliary circuits, further reducing circuit complexity and cost, while ensuring rapid transmission of control signals in the event of control unit failure.

[0010] In one embodiment of the present invention, the control circuit further includes: a plurality of main diodes corresponding to the function switches, the cathodes of the main diodes being connected to the switch output terminals of the corresponding function switches, and the anodes of the main diodes being connected to the control unit through a voltage divider unit; and a plurality of pull-up resistors corresponding to the main diodes, one end of the pull-up resistors being connected to the power interface, and the other end of the pull-up resistors being connected to the anodes of the corresponding main diodes.

[0011] Compared with existing technologies, the technical effects achieved by this solution are as follows: The main diode is dedicated to transmitting the switch signal to the control unit, further enhancing the unidirectional transmission characteristic of the switch signal, preventing the control unit's output signal from interfering with the function switch in the reverse direction, and improving the independence and stability of signal transmission; the pull-up resistor pulls the signal terminal to the power supply voltage when the function switch is off, enabling the control unit to stably detect "invalid" high levels, avoiding misjudgments caused by floating signals, and is especially suitable for the complex electronic environment of vehicles, improving the reliability of signal detection; the voltage divider unit divides the vehicle power supply voltage to the input range suitable for the control unit, preventing high voltage direct input from burning out the control unit, extending the service life of the control unit, and ensuring the accuracy of signal detection; the main diode, pull-up resistor, and voltage divider unit form a complete signal preprocessing circuit, effectively filtering out some electromagnetic interference, improving the stability of the switch signal, and reducing the malfunction of the control unit.

[0012] In one embodiment of the present invention, the signal generation module includes: a low-speed wiper switch, a high-speed wiper switch, and a light switch; the execution module includes: a first relay, a second relay, and a third relay, wherein the first relay and the low-speed wiper switch, the second relay and the high-speed wiper switch, and the third relay and the light switch are all connected via spare diodes.

[0013] Compared with existing technologies, the technical effects achieved by adopting this solution are as follows: the low-speed wiper switch and the first relay, the high-speed wiper switch and the second relay, and the light switch and the third relay are all connected through corresponding spare diodes, forming a unified connection logic, which simplifies circuit design and reduces circuit redundancy; the high and low speed wiper control and the light control share the same set of hardware spare control logic, eliminating the need to design separate spare circuits for different functions, further reducing costs and system complexity, while improving the consistency and reliability of the control logic.

[0014] In one embodiment of the present invention, the signal input interface includes: a low-speed wiper signal input terminal, a high-speed wiper signal input terminal, and a headlight signal input terminal; one end of the low-speed wiper switch is connected to the low-speed wiper signal input terminal, and the other end is grounded; one end of the high-speed wiper switch is connected to the high-speed wiper signal input terminal, and the other end is grounded; one end of the headlight switch is connected to the headlight signal input terminal, and the other end is grounded.

[0015] Compared with existing technologies, the technical effects achieved by this solution are as follows: The function switch adopts a connection method of "one end connected to the corresponding signal input terminal and the other end grounded", which is simple in structure and realizes the low-effectiveness design of the switch signal (the signal is low level when the switch is closed and grounded; the signal is floating when the switch is open and pulled up to a high level by the pull-up resistor), ensuring stable transmission of the switch signal and improving the reliability of signal detection. The direct grounding connection of the function switch reduces interference points in the signal transmission path, reduces the impact of electrostatic and electromagnetic interference on the switch signal, and enables the control unit to accurately identify the switch state, thereby improving control accuracy.

[0016] In one embodiment of the present invention, the functional output interface includes: a low-speed wiper output terminal, a high-speed wiper output terminal, and a headlight output terminal; a first relay is provided with a first moving contact, a first normally open contact, and a first normally closed contact, the first normally open contact being connected to a power interface, and the first normally closed contact being grounded; a second relay is provided with a second moving contact, a second normally open contact, and a second normally closed contact, the second moving contact being connected to the first moving contact, the second normally open contact being connected to the high-speed wiper output terminal, and the second normally closed contact being connected to the low-speed wiper output terminal; a third relay is provided with a third moving contact, a third normally open contact, and a third normally closed contact, the third moving contact being connected to the headlight output terminal, the third normally open contact being connected to a power interface, and the third normally closed contact being grounded.

[0017] Compared with existing technologies, the technical effects achieved by this solution are as follows: The first normally open contact of the first relay is connected to the power interface, and the first normally closed contact is grounded. The second moving contact of the second relay is connected to the first moving contact, the second normally open contact is connected to the high-speed wiper output terminal, and the second normally closed contact is connected to the low-speed wiper output terminal. Through the coordinated action of the two relays, a simple switching between high and low speed wipers is achieved without complex logic control, improving switching reliability and response speed. The third normally open contact of the third relay is connected to the power interface, the third normally closed contact is grounded, and the third moving contact is connected to the headlight output terminal, ensuring that the headlight can be stably powered on when the headlight switch is effective and reliably powered off when it is ineffective, improving the stability of headlight control. The functional output interfaces are clearly divided into the low-speed wiper output terminal, the high-speed wiper output terminal, and the headlight output terminal. The interface definitions are clear, and the interfaces are highly compatible with the wiper motor and headlight load, facilitating wiring and maintenance.

[0018] In one embodiment of the present invention, the drive module includes: a low-speed wiper drive chip, which is connected to the control unit and the coil control terminal of the first relay; a high-speed wiper drive chip, which is connected to the control unit and the coil control terminal of the second relay; and a headlight drive chip, which is connected to the control unit and the coil control terminal of the third relay.

[0019] Compared with existing technologies, the technical effects achieved by this solution are as follows: the drive module has dedicated drive chips for low-speed wipers, high-speed wipers, and headlight control, realizing independent design of the drive circuit, avoiding drive interference between different functions, and improving the stability and reliability of relay operation.

[0020] In one embodiment of the present invention, the control circuit further includes: a plurality of capacitors corresponding to the function switches, one end of the capacitors being connected to the switch output terminal of the corresponding function switch, and the other end of the capacitors being grounded.

[0021] Compared with existing technologies, the technical effects achieved by this solution are as follows: one end of the capacitor is connected to the switch output terminal of the function switch, and the other end is grounded, forming a filter circuit. This effectively absorbs electrostatic pulses in the vehicle's electronic environment, protecting the control unit's input port and the function switch contacts from electrostatic breakdown damage. The capacitor can filter out bouncing noise when the function switch is closed / opened, making the switch signal waveform more stable and preventing the control unit from misdetecting the switch state due to noise, thus improving control accuracy. At the same time, it reduces relay malfunctions caused by noise and extends the life of relay contacts.

[0022] In one embodiment of the present invention, the light switch is one or more combinations of a high beam switch, a low beam switch, a brake light switch, or a position light switch.

[0023] Compared with existing technologies, the technical effects achieved by adopting this technical solution are as follows: the light switch can flexibly select one or more combinations of high beam switch, low beam switch, brake light switch or position light switch, adapting to the lighting configuration requirements of different vehicle models, greatly expanding the applicability of the control circuit and improving the versatility of the product.

[0024] By adopting the technical solution of the present invention, the following technical effects can be achieved: (1) Before the switch signal is acquired by the hardware circuit, it is directly connected to the coil control terminal of the corresponding execution module through the hardware backup control module. This is used to automatically realize the control function required by the vehicle through the hardware backup control module when the control unit fails, so as to realize the seamless takeover of the vehicle's required function and improve the continuity of control. (2) The setting of the backup diode makes the hardware backup control path structure extremely simple, without the need for complex auxiliary circuits, further reducing circuit complexity and cost, while ensuring the rapid transmission of control signals when the control unit fails; (3) The function switch adopts the connection method of "one end connected to the corresponding signal input terminal and the other end grounded", which is simple in structure, realizes the low effective design of the switch signal, ensures the stable transmission of the switch signal, and improves the reliability of signal detection. Attached Figure Description

[0025] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings to be used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort. Figure 1 The circuit diagram shows an automatic anti-failure control circuit for automotive windshield wipers and lights, as provided in Embodiment 1 of the present invention.

[0026] Explanation of reference numerals in the attached figures: 110. Power interface; 121. Low-speed wiper signal input terminal; 122. High-speed wiper signal input terminal; 123. Headlight signal input terminal; 131. Low-speed wiper output terminal; 132. High-speed wiper output terminal; 133. Headlight output terminal; 140. Ground terminal; 211. Low-speed wiper switch; 212. High-speed wiper switch; 213. Headlight switch; 311. First moving contact; 312. First normally open contact; 313. First normally closed contact; 321. Second moving contact; 322. Second normally open contact; 323. Second normally closed contact; 331. Third moving contact; 332. Third normally open contact; 333. Third normally closed contact. Detailed Implementation

[0027] To make the above-mentioned objectives, features, and advantages of the present invention more apparent and understandable, the technical solutions in the embodiments of the present invention are clearly and completely described. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0028] Example 1 See Figure 1 This is a circuit diagram of an automatic anti-failure control circuit for automotive windshield wipers and lights provided in the first embodiment of the present invention. The control circuit has a power interface 110, a signal input interface, and a function output interface. The control circuit includes: a signal generation module, a control unit, a drive module, an execution module, and a hardware backup control module. The control unit is connected to the execution module through the drive module, receives a switch signal from the signal generation module through the signal input interface, and outputs a control signal. The execution module is connected to the function output interface and performs control actions according to the control signal to control the on / off state of the controlled device connected to the function output interface. The hardware backup control module is connected to the signal generation module and the execution module. When the switch signal is low and the control unit is in a failure state, the execution module is directly controlled by the hardware backup control module.

[0029] In one specific embodiment, U1 is a control unit. Power interface 110 is connected to the vehicle's power supply VBAT (compatible with 12V passenger vehicles or 24V commercial vehicles), and ground terminal 140 is connected to the vehicle body ground. The signal input interface serves as the switch signal input for the control circuit. All switch signals are acquired using pure hardware. The acquired switch signals are sent to the control unit for processing. The control unit drives the execution module through the drive module, thereby controlling the functions required by the vehicle. Simultaneously, before being acquired by the hardware circuit, the switch signals are directly connected to the coil control terminal of the corresponding execution module through the corresponding backup diode in the hardware backup control module. This allows the hardware backup control module to automatically implement the vehicle's required control functions in case of control unit failure, achieving zero-delay takeover of the vehicle's required functions and improving control continuity. Furthermore, it eliminates the need for an additional watchdog chip and dedicated power supply, simplifying the control circuit structure, reducing the number of components, and lowering production costs and failure risks.

[0030] The control circuit mainly implements the high and low speed control of the windshield wipers and the control of the lights. The operating mode of the control circuit can be divided into normal mode and failure mode: In normal mode, the control functions required by the vehicle are implemented by the control unit, including low speed control of the wipers, high speed control, wiper switch, and light switch 213. In failure mode (once the control unit fails, whether it is a hardware failure or a software failure, as long as the control signal output by the control unit is lost), and the switch signal is valid at this time, the hardware backup control module can automatically implement the high and low speed control of the wipers and the control of the lights. At the same time, it can also implement the wiper switch and light switch 213 functions. That is, the driver can turn off the wipers or lights, or turn on the wipers and lights, through the control signal generation module. After the control unit fails, the hardware backup control module will immediately take over the wiper and light control functions without any time delay or response issues. After the control unit returns to normal, the hardware backup control module is automatically disabled without affecting the normal control logic of the control unit.

[0031] Furthermore, the signal generation module includes: multiple function switches; the execution module includes: multiple relays corresponding to the function switches; the hardware backup control module includes: multiple backup diodes corresponding to the function switches, with the cathodes of the backup diodes connected to the switch output terminals of the corresponding function switches and the anodes of the backup diodes connected to the coil control terminals of the corresponding relays.

[0032] Specifically, the functional circuits corresponding to each function switch are exactly the same. The multiple function switches of the signal generation module correspond one-to-one with the multiple relays of the execution module, and the backup diodes of the hardware backup control module also correspond one-to-one with the function switches, forming a precise one-to-one control relationship, avoiding signal interference between different functions, and improving control accuracy. The switch output terminal of the function switch is connected to the corresponding signal input interface, and the signal input interface can also be regarded as the switch output terminal.

[0033] The backup control module utilizes a backup diode. In failure mode, when the function switch is closed, the backup diode immediately conducts, maintaining power supply to the corresponding relay and ensuring its continuous output. The backup diode is connected with its cathode to the function switch output and its anode to the relay coil control terminal. Leveraging the diode's unidirectional conduction characteristic, it enables one-way transmission of the switch signal to the relay, preventing reverse signal flow, protecting the function switch and relay coil, and improving circuit stability. Furthermore, the backup diode simplifies the hardware backup control path structure, eliminating the need for complex auxiliary circuits, further reducing circuit complexity and cost, while ensuring rapid transmission of control signals in the event of control unit failure.

[0034] Furthermore, the control circuit also includes: multiple main diodes corresponding to the function switches, with the cathodes of the main diodes connected to the switch output terminals of the corresponding function switches, and the anodes of the main diodes connected to the control unit through a voltage divider unit; and multiple pull-up resistors corresponding to the main diodes, with one end of the pull-up resistor connected to the power interface 110 and the other end of the pull-up resistor connected to the anode of the corresponding main diode.

[0035] Specifically, R1, R2, and R3 are all pull-up resistors; D11 is the main diode between the low-speed wiper switch 211 and the first relay; D21 is the main diode between the high-speed wiper switch 212 and the second relay; and D31 is the main diode between the light switch 213 and the third relay. The main diodes are connected in series between the function switches and the control unit, specifically responsible for transmitting the switch signals to the control unit. In normal mode: when the function switch is open, it is ineffective; the corresponding signal input interface is floating, and the port voltage of the signal input interface is pulled up to the power supply voltage through the corresponding pull-up resistor. The control unit detects a high level, indicating ineffectiveness, thus avoiding misjudgments caused by floating signals. This is especially suitable for the complex electronic environment of vehicles, improving the reliability of signal detection. When the function switch is closed, it is effective; the corresponding signal input interface is grounded, and the pull-up voltage of the corresponding pull-up resistor is grounded through the corresponding main diode. The control unit detects a low level, indicating effectiveness. The control unit drives the corresponding relay through the driver module to realize the function corresponding to the closed function switch.

[0036] The primary and backup diodes have clearly defined roles. The primary diode is specifically responsible for transmitting the switching signal to the control unit, further enhancing the unidirectional signal transmission characteristic and preventing the control unit's output signal from interfering with the function switch in the reverse direction, thus improving the independence and stability of signal transmission. The primary diode, pull-up resistor, and voltage divider unit form a complete signal preprocessing circuit, effectively filtering out some electromagnetic interference, improving the stability of the switching signal, and reducing malfunctions of the control unit. When the function switch is open, the pull-up resistor pulls the signal terminal up to the power supply voltage, enabling the control unit to stably detect "invalid" high levels, avoiding misjudgments caused by floating signals, and is especially suitable for the complex electronic environment of vehicles, improving the reliability of signal detection.

[0037] Furthermore, the signal generation module includes: a low-speed wiper switch 211, a high-speed wiper switch 212, and a light switch 213; the execution module includes: a first relay, a second relay, and a third relay, wherein the first relay and the low-speed wiper switch 211, the second relay and the high-speed wiper switch 212, and the third relay and the light switch 213 are all connected via spare diodes.

[0038] Specifically, the function switches include a low-speed wiper switch 211, a high-speed wiper switch 212, and a headlight switch 213. The corresponding switch signals are the low-speed wiper switch 211 signal, the high-speed wiper switch 212 signal, and the headlight switch 213 signal, respectively. These three types of switch signals control the low-speed wiper, high-speed wiper, and headlight functions, achieving precise control and independent switching of functions. The corresponding relays include a first relay K1, a second relay K2, and a third relay K3, all of which are single-pole double-throw relays. D12 is a spare diode between the low-speed wiper switch 211 and the first relay; D22 is a spare diode between the high-speed wiper switch 212 and the second relay; and D32 is a spare diode between the headlight switch 213 and the third relay. In this application, the high / low speed wiper control and headlight control share the same set of hardware backup control logic, eliminating the need to design separate backup circuits for different functions. This further reduces cost and system complexity, while improving the consistency and reliability of the control logic.

[0039] Preferably, taking the low-speed wiper control as an example, the low-speed wiper switch 211 signal is connected to the cathode of the corresponding main diode D11, the anode of D11 is connected to one end of R1 and R11, the other end of R1 is connected to the power supply voltage, one end of R11 and R12 is connected to the input port of the control unit, and the other end of R12 is grounded. The voltage division function is realized through the voltage divider unit composed of R11 and R12.

[0040] Taking the high-speed wiper control as an example, the high-speed wiper switch 212 signal is connected to the cathode of the corresponding main diode D21. The anode of D21 is connected to one end of R2 and R21, and the other end of R2 is connected to the power supply voltage. One end of R21 and R22 is connected to the input port of the control unit, and the other end of R22 is grounded. The voltage division function is realized through the voltage divider unit composed of R21 and R22.

[0041] Taking lighting function control as an example, the light switch 213 signal is connected to the cathode of the corresponding main diode D31, the anode of D31 is connected to one end of R3 and R31, the other end of R3 is connected to the power supply voltage, one end of R31 and R32 is connected to the input port of the control unit, and the other end of R32 is grounded. The voltage division function is realized through the voltage divider unit composed of R31 and R32.

[0042] Furthermore, the signal input interface includes: a low-speed wiper signal input terminal 121, a high-speed wiper signal input terminal 122, and a headlight signal input terminal 123; one end of the low-speed wiper switch 211 is connected to the low-speed wiper signal input terminal 121, and the other end is grounded; one end of the high-speed wiper switch 212 is connected to the high-speed wiper signal input terminal 122, and the other end is grounded; one end of the headlight switch 213 is connected to the headlight signal input terminal 123, and the other end is grounded.

[0043] Specifically, the high-speed wiper switch 212 signal, the low-speed wiper switch 211 signal, and the light switch 213 signal are all low-activity switch signals. They are connected by a function switch with one end connected to the corresponding signal input terminal and the other end grounded. This simple structure achieves a low-activity design for the switch signals (the signal is low when the switch is closed and grounded; the signal is floating when the switch is open and pulled up to a high level by a pull-up resistor), ensuring stable transmission of the switch signals and improving the reliability of signal detection.

[0044] Furthermore, the functional output interfaces include: a low-speed wiper output terminal 131, a high-speed wiper output terminal 132, and a headlight output terminal 133; the first relay is provided with a first moving contact 311, a first normally open contact 312, and a first normally closed contact 313, the first normally open contact 312 being connected to the power interface 110, and the first normally closed contact 313 being grounded; the second relay is provided with a second moving contact 321, a second normally open contact 322, and a second normally closed contact 323, the second moving contact 321 being connected to the first moving contact 311, the second normally open contact 322 being connected to the high-speed wiper output terminal 132, and the second normally closed contact 323 being connected to the low-speed wiper output terminal 131; the third relay is provided with a third moving contact 331, a third normally open contact 332, and a third normally closed contact 333, the third moving contact 331 being connected to the headlight output terminal 133, the third normally open contact 332 being connected to the power interface 110, and the third normally closed contact 333 being grounded.

[0045] Specifically, during low-speed wiper control: with the low-speed wiper switch 211 closed, the coil of the first relay K1 is energized, while the coil of the second relay K2 is de-energized. The first moving contact 311 closes to the first normally open contact 312 (power interface 110), and the second moving contact 321 closes to the second normally closed contact 323 (low-speed wiper output terminal 131). The low-speed winding of the wiper motor receives power through the low-speed wiper output terminal 131, enabling low-speed wiper operation. During high-speed wiper control: with the high-speed wiper switch 212 closed, both the coils of the first relay K1 and the second relay K2 are energized. The first moving contact 311 closes to the first normally open contact 312, and the second moving contact 321 closes to the second normally open contact 322 (high-speed wiper output terminal 132). The high-speed winding of the wiper motor receives power through the high-speed wiper output terminal 132, enabling high-speed wiper operation. When controlling the lights: When the light switch 213 is closed, the coil of the third relay K3 is energized, the third moving contact 331 is attracted to the third normally open contact 332 (power interface 110), and the light load obtains power through the light output terminal 133 to turn on the lights; when the coil of the third relay K3 is de-energized, the third moving contact 331 is attracted to the third normally closed contact 333 (grounded), the light load is de-energized, and the lights are turned off.

[0046] Furthermore, the drive module includes: a low-speed wiper drive chip, which is connected to the control unit and the coil control terminal of the first relay; a high-speed wiper drive chip, which is connected to the control unit and the coil control terminal of the second relay; and a headlight drive chip, which is connected to the control unit and the coil control terminal of the third relay.

[0047] Specifically, U21 is the low-speed wiper driver chip, U22 is the high-speed wiper driver chip, and U23 is the headlight driver chip, all of which are low-side driver chips. During low-speed wiper control: the low-speed wiper control signal output from the control unit is input to the input terminal of the low-speed wiper driver chip, and the output terminal of the low-speed wiper driver chip is connected to the coil control terminal of the first relay. During high-speed wiper control: the high-speed wiper control signal output from the control unit is input to the input terminal of the high-speed wiper driver chip, and the output terminal of the high-speed wiper driver chip is connected to the coil control terminal of the second relay. During headlight control: the headlight control signal output from the control unit is input to the input terminal of the headlight driver chip, and the output terminal of the headlight driver chip is connected to the coil control terminal of the third relay. The driver module amplifies the weak signal output from the control unit, providing sufficient drive current to the relay coil to ensure reliable relay operation, while also protecting the control unit output port.

[0048] Furthermore, the control circuit also includes: multiple capacitors corresponding to the function switches, one end of the capacitors being connected to the switch output terminal of the corresponding function switch, and the other end of the capacitors being grounded.

[0049] Specifically, C1, C2, and C3 are capacitors corresponding to the low-speed wiper switch 211, the high-speed wiper switch 212, and the headlight switch 213, respectively. One end of capacitor C1 is connected to the output terminal of the low-speed wiper switch 211, and the other end is grounded; one end of capacitor C2 is connected to the output terminal of the high-speed wiper switch 212, and the other end is grounded; one end of capacitor C3 is connected to the output terminal of the headlight switch 213, and the other end is grounded. The capacitors serve to prevent static electricity and filter signals, absorbing electrostatic pulses, filtering switch bounce noise, and improving the stability of the switch signals.

[0050] Furthermore, the light switch 213 is one or more combinations of a high beam switch, a low beam switch, a brake light switch, or a position light switch.

[0051] Specifically, depending on the lighting configuration requirements of the vehicle model, the light switch 213 can be selected as a high beam switch, low beam switch, brake light switch, or position light switch. Multiple light switches 213 can also be set to control different types of lights respectively. Multiple corresponding third relays K3 can be set. Each light switch 213 is connected to the corresponding relay through a corresponding spare diode and driver chip to realize independent control of multiple types of lights and adapt to the needs of different vehicle models.

[0052] In a specific embodiment, during normal operation, taking the wiper low-speed switch 211 as an example, it is ineffective when the switch is open. At this time, the wiper low-speed signal input terminal 121 is floating, and the port voltage of the wiper low-speed signal input terminal 121 is pulled up to the power supply voltage through R1. The MCU detects a high level, which means it is ineffective. When the switch is closed, it is effective. At this time, the wiper low-speed signal input terminal 121 is grounded, and the pull-up voltage of R1 is grounded through the main diode D11. The MCU detects a low level, which means it is effective. When the wiper low-speed switch 211 is effective, the MCU drives K1 through U21, and the wiper outputs at low speed. Theoretically, after the wiper low-speed switch 211 is closed, the K1 coil is grounded through D12, and the K1 contact is energized. However, in reality, the wiper switch will bounce, usually for about 20ms. After the relay is powered on, the contact will also bounce, for about 10ms. Therefore, it takes about 30ms for the wiper switch state to stabilize and the relay contact state to stabilize. Ignoring the relay's actuation time, when the MCU is working normally, the software delay from the wiper switch stabilizing to the MCU output is extremely short and almost negligible. Therefore, under normal conditions, taking the low-speed wiper switch 211 as an example, after the low-speed wiper switch 211 closes, D12 will conduct for a very short time, and U21 will also conduct simultaneously. Since D12 is a diode, its forward voltage drop is around 1V, while U21 is a low-side intelligent MOS switch with almost no forward voltage drop. Therefore, D12 will turn off immediately after U21 conducts. In summary, under normal operation, once the low-speed wiper switch 211 closes, D12 will conduct briefly, and then after U21 conducts, D12 will turn off. During this transition, the control of K1 is unaffected, and the low-speed wiper output terminal 131 remains effective.

[0053] Taking the low-speed wiper function as an example, during the low-speed wiper function's enabling process, if the MCU fails—whether it's a software or hardware failure—as long as the MCU's control signal for U21 fails, U21 will turn off. At this time, as long as the low-speed wiper switch 211 remains active, D12 will immediately conduct, maintaining power supply to the K1 coil. In other words, during this transition, the control of K1 is unaffected, the low-speed wiper output terminal 131 remains active, and there will be no interruption. However, with a watchdog timer, the hardware anti-failure circuit must wait until the timer overflows before enabling, resulting in a brief functional failure. This failure time depends on the watchdog timer cycle, typically several hundred milliseconds. Several hundred milliseconds may not significantly affect the wiper function, but it is crucial for the headlight function during nighttime driving. When the MCU fails, the high and low speed wiper functions remain under control. For example, if the low-speed wiper switch 211 is turned off, D12 will be cut off, K1 will be turned off, and the low-speed wiper output will be turned off.

[0054] Compared to the low-speed wiper function, the signal detection, control, and automatic anti-failure principle of the high-speed wiper function are basically similar. The only difference is that when the MCU is functioning normally, if the high-speed wiper switch 212 is closed, D22 and D4 will both conduct briefly simultaneously, and K1 and K2 will operate simultaneously. When the MCU detects that the high-speed wiper switch 212 is active, it will also enable U21 and U22 simultaneously. At this time, D22 and D4 will immediately turn off, and the control of K1 and K2 will not be affected. Because the first moving contact 311 of K1 is connected to the second moving contact 321 of K2, the second normally closed contact 323 of K2 is the low-speed wiper output terminal 131, and the second normally open contact 322 is the high-speed wiper output terminal 132, when K1 and K2 are simultaneously engaged, the output of K2 is the high-speed wiper function. Therefore, regardless of whether the MCU is functioning normally, when the high-speed wiper switch 212 is active, the circuit output is the high-speed wiper function; when the high-speed wiper switch 212 is inactive, the circuit stops outputting.

[0055] The driving principle of the lights is basically similar to that of the windshield wipers. When the light switch 213 is active, D31 is turned on, and the MCU detects that the light switch 213 is active. The MCU drives U23 to turn on, and U23 drives K3, so the light output is active. When the light switch 213 is active, D32 will be turned on briefly, but after U23 turns on, D32 will be turned off immediately. During this transition, the control of K3 is not affected, and the light output remains active.

[0056] In summary, when the wiper switch or light switch 213 is active, the signal is split into two parts via a diode. One part is sent to the MCU for switch signal detection, and the other part is directly used to drive the relay coil. When the MCU is working normally, it controls the low-side driver chip to drive the relay, thereby controlling the wipers and lights. If the MCU fails, its output signal fails, and the wiper and light relays form a circuit through the backup diode and the function switch. The relays remain closed, achieving automatic fail-safe functionality. Because this fail-safe circuit uses a backup diode, it automatically turns off when the MCU is working properly and automatically turns on when the MCU fails, with no delay during function switching. Therefore, when the MCU is working properly, after the switch signal is active, D12, D22, D32, or D4 will only briefly conduct and then immediately turn off. The wiper switch and light switch 213 will only experience a very short-term relay coil current surge, typically around 50mA, which will not shorten the switch contact life but will instead help remove the contact oxide layer and extend the switch contact life. When the MCU fails, if the switch signal is valid, the relay coil current will be directly grounded through the backup diode and the function switch. In other words, the relay coil is directly controlled by the function switch, so the state is abnormal. The time will not last too long, and the probability of it occurring during the vehicle's lifespan is very low. Moreover, a current of about 50mA is within the allowable range for the wiper switch and the light switch 213. Short-term use will not affect the lifespan of the switch contacts, nor will it damage the vehicle.

[0057] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A control circuit for an automatic anti-failure automotive windshield wiper and lights, characterized in that, The control circuit is provided with a power interface (110), a signal input interface and a function output interface. The control circuit includes: a signal generation module, a control unit, a drive module, an execution module and a hardware backup control module. The control unit is connected to the execution module through the drive module, and receives the switch signal from the signal generation module and outputs the control signal through the signal input interface; The execution module is connected to the function output interface and performs control actions according to the control signal to control the on / off state of the controlled device connected to the function output interface; The hardware backup control module is connected to the signal generation module and the execution module; When the switch signal is low and the control unit is in a failed state, the execution module is directly controlled by the hardware backup control module. The signal generation module includes: multiple function switches; The execution module includes: a plurality of relays corresponding to the function switch; The hardware backup control module includes: multiple backup diodes corresponding to the function switch, wherein the cathode of the backup diode is connected to the switch output terminal of the function switch, and the anode of the backup diode is connected to the coil control terminal of the relay.

2. The control circuit according to claim 1, characterized in that, The control circuit also includes: Multiple main diodes corresponding to the function switches, the cathodes of the main diodes are connected to the switch output terminals corresponding to the function switches, and the anodes of the main diodes are connected to the control unit through a voltage divider unit; Multiple pull-up resistors corresponding to the main diode, one end of the pull-up resistor is connected to the power interface (110), and the other end of the pull-up resistor is connected to the anode of the corresponding main diode.

3. The control circuit according to claim 2, characterized in that, The signal generation module includes: a low-speed wiper switch (211), a high-speed wiper switch (212), and a headlight switch (213); The execution module includes a first relay, a second relay, and a third relay. The first relay and the low-speed wiper switch (211), the second relay and the high-speed wiper switch (212), and the third relay and the light switch (213) are all connected through the spare diode.

4. The control circuit according to claim 3, characterized in that, The signal input interface includes: a low-speed wiper signal input terminal (121), a high-speed wiper signal input terminal (122), and a headlight signal input terminal (123); One end of the wiper low speed switch (211) is connected to the wiper low speed signal input terminal (121), and the other end is grounded; One end of the high-speed wiper switch (212) is connected to the high-speed wiper signal input terminal (122), and the other end is grounded; One end of the light switch (213) is connected to the light signal input terminal (123), and the other end is grounded.

5. The control circuit according to claim 3, characterized in that, The functional output interfaces include: a low-speed wiper output terminal (131), a high-speed wiper output terminal (132), and a headlight output terminal (133); The first relay is provided with a first moving contact (311), a first normally open contact (312) and a first normally closed contact (313). The first normally open contact (312) is connected to the power interface (110), and the first normally closed contact (313) is grounded. The second relay is provided with a second moving contact (321), a second normally open contact (322), and a second normally closed contact (323). The second moving contact (321) is connected to the first moving contact (311), the second normally open contact (322) is connected to the high-speed output terminal (132) of the wiper, and the second normally closed contact (323) is connected to the low-speed output terminal (131) of the wiper. The third relay is provided with a third moving contact (331), a third normally open contact (332) and a third normally closed contact (333). The third moving contact (331) is connected to the light output terminal (133), the third normally open contact (332) is connected to the power interface (110), and the third normally closed contact (333) is grounded.

6. The control circuit according to claim 5, characterized in that, The driving module includes: A low-speed wiper drive chip, wherein the low-speed wiper drive chip is connected to the control unit and the coil control terminal of the first relay; A high-speed wiper drive chip, wherein the high-speed wiper drive chip is connected to the control unit and the coil control terminal of the second relay; A light driver chip, which is connected to the control unit and the coil control terminal of the third relay.

7. The control circuit according to claim 2, characterized in that, The control circuit also includes: Multiple capacitors corresponding to the function switch, one end of each capacitor is connected to the switch output terminal corresponding to the function switch, and the other end of each capacitor is grounded.

8. The control circuit according to claim 3, characterized in that, The light switch (213) is one or more of the following: high beam switch, low beam switch, brake light switch, or position light switch.

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