An automotive reverse detection circuit

Abstract

The present invention is an automobile reverse detection circuit. The circuit includes a voltage control unit, a filtering unit, a first switch unit, a current limiting unit, a second-order filtering unit, and a second switch unit. The voltage control unit is configured to filter out high-voltage signals in the received original reverse signal. The filtering unit is configured to filter out high-frequency clutter in the clamping voltage. The first switch unit is configured to filter out low-voltage interference signals in the reverse signal. The current limiting unit is configured to limit the current of the gating unit and divide the voltage of the control unit. The second-order filtering unit is configured to smooth the reverse signal after removing the high-voltage signal and high-frequency clutter, thereby reducing the oscillation and noise of the system and improving the stability of the system. The second switch unit is configured to control the connection between the reverse signal and the vehicle controller. The purpose is to solve the problems of high cost and complex circuit of the existing automobile reverse detection circuit.

Description

Technical Field

[0001] The present invention relates to a detection circuit, in particular to an automotive reverse detection circuit. Background Art

[0002] With the popularization of automobiles, automotive-related electronic products have been developing at an increasingly high speed, and the number of electronic devices installed in automobiles has been continuously increasing, such as driving recorders, reverse assistance systems, surround view systems, etc. These systems often need to obtain the vehicle body status to obtain a better product experience. These vehicle body statuses generally include whether the reverse gear is engaged. To obtain this data, it can be obtained through the CAN bus. However, although this method has high reliability, the circuit is relatively complex and the cost is relatively high. Another method is to detect through a pure hardware circuit. Currently, most of the existing pure hardware vehicle inspection circuits for automotive reverse detection are implemented by means of optocoupler isolation. However, the cost is also relatively high when using the optocoupler isolation method. Summary of the Invention

[0003] The purpose of the present invention is to solve the problems of relatively high cost and relatively complex circuit of the existing automotive reverse detection circuit.

[0004] An automotive reverse detection circuit, the circuit includes a voltage-controlled unit, a filtering unit, a first switching unit, a current-limiting unit, a second-order filtering unit, and a second switching unit.

[0005] The voltage-controlled unit: is used to filter out the high-voltage signal in the received original reverse signal.

[0006] The filtering unit: is used to filter out the high-frequency clutter in the clamped voltage.

[0007] The first switching unit: is used to filter out the low-voltage interference signal in the reverse signal.

[0008] The current-limiting unit: is used to limit the current of the gating unit and divide the voltage of the control unit.

[0009] The second-order filtering unit: is used to smooth the reverse signal after removing the high-voltage signal and high-frequency clutter, thereby reducing the oscillation and noise of the system and improving the stability of the system.

[0010] The second switching unit: is used to control the connection between the reverse signal and the vehicle controller.

[0011] Further, the voltage-controlled unit includes a transient voltage suppression diode D1.

[0012] Further, the filtering unit includes a ferrite bead FB1 and a capacitor C1.

[0013] Further, the first switching unit includes a zener diode Z1.

[0014] Further, the current limiting unit includes a resistor R2 and a resistor R3.

[0015] Further, the second-order filtering unit includes a capacitor C2.

[0016] Further, the second switching unit includes a triode Q1.

[0017] The beneficial effects of adopting the above technical solution are as follows: The cost of the vehicle reverse detection circuit in this solution is relatively low and the reliability is more stable and reliable. In this solution, in addition to the added TVS diode and filtering devices, the key of the present invention lies in the use of the TVS diode D1 and the voltage stabilizing diode Z1: The transient pulse higher than the clamping voltage of the TVS diode will break down the TVS diode D1, thereby protecting the subsequent circuit components. The interference voltage lower than the Zener voltage of the voltage stabilizing diode cannot break down the voltage stabilizing diode, and the base 1 pin of the triode still remains pulled down (low level), and the triode will not enter the amplification state. Only the normal signal lower than the clamping voltage of the TVS diode D1 and higher than the breakdown voltage of Z1 can be sent to the base of the triode Q1, so that the controller can identify whether the reverse is turned on. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 It is a block diagram of the vehicle reverse detection circuit described in the present invention.

[0019] Figure 2 It is a circuit diagram of the vehicle reverse detection circuit described in the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0020] The following further describes the content of the present invention in conjunction with the accompanying drawings and the preferred specific embodiments of the present invention. The examples given are only used to explain the present invention and are not used to limit the scope of the present invention.

[0021] As Figure 1 and Figure 2 shown, in the solution described, a vehicle reverse detection circuit, the circuit includes a voltage control unit, a filtering unit, a first switching unit, a current limiting unit, a second-order filtering unit and a second switching unit,

[0022] The voltage control unit: used to filter out the high-voltage signal in the received original reverse signal;

[0023] The filtering unit: used to filter out the high-frequency clutter in the clamping voltage;

[0024] The first switching unit: used to filter out the low-voltage interference signal in the reverse signal;

[0025] The current limiting unit: used to limit the current of the gating unit and divide the voltage of the control unit;

[0026] The second - order filtering unit: It is used to smooth the reverse signal after removing the high - voltage signal and high - frequency clutter, thereby reducing the oscillation and noise of the system and improving the stability of the system;

[0027] The second switching unit: It is used to control the connection between the reverse signal and the vehicle controller; In this solution, the voltage - controlled unit includes a transient voltage suppression diode D1; The filtering unit includes a ferrite bead FB1 and a capacitor C1; The first switching unit includes a zener diode Z1; The current - limiting unit includes resistors R2 and R3; The second - order filtering unit includes a capacitor C2; The second switching unit includes a triode Q1.

[0028] During specific implementation, the reverse signal REV is connected to the host through a wire harness. First, it passes through the transient voltage suppression diode D1. The positive electrode of the transient voltage suppression diode D1 is connected to the reverse signal, and the negative electrode is grounded, which can filter out the high - voltage signal and clamp the voltage within a certain range. The ferrite bead FB1 and the capacitor C1 form a filtering network to filter out high - frequency clutter. One leg of the ferrite bead FB1 is connected to the transient voltage suppression diode D1, and the other leg of the ferrite bead FB1 is connected to the capacitor C1 and the zener diode Z1. One leg of the capacitor C1 is connected to the ferrite bead FB1 and the zener diode Z1, and the other leg of the capacitor C1 is grounded. The reverse signal after passing through the filtering network reaches the negative electrode 2 - pin of the zener diode Z1. After REV breaks down the zener diode Z1, it exits from the 1 - pin of the zener diode Z1. The resistors R2 and R3 serve as the current - limiting resistor of the zener diode Z1 and the current - limiting and voltage - dividing resistors of the triode Q1, preventing the zener diode Z1 from being burned out due to over - current and the triode Q1 from being burned out due to over - current and over - voltage. At the same time, the resistor R3 serves as the pull - down resistor of the base of the triode Q1 to keep the triode Q1 in a stable state. One leg of the capacitor C2 is connected to the resistors R2, R3, and the base of the triode Q1, and the other leg of the capacitor C2 is grounded, playing a role of second - order filtering. After the REV signal turns on the triode Q1, the 3 - pin and 2 - pin of the triode Q1 are conducted, and the REV_OUT originally pulled high by the resistor R1 in the triode Q1 is pulled to the ground, so that the controller (such as MCU) detects the reverse signal.

[0029] The above - mentioned are only the preferred embodiments of the present invention, and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. An automobile reverse detection circuit, characterized in that, The circuit includes a voltage control unit, a filtering unit, a first switching unit, a current limiting unit, a second-order filtering unit, and a second switching unit, where: The voltage control unit is used to filter out the high-voltage signal in the received original reverse signal, and its output terminal is connected to the input terminal of the filtering unit. The voltage control unit includes a transient voltage suppression diode D1. The positive electrode of the transient voltage suppression diode D1 receives the original reverse signal, and the negative electrode is grounded; The filtering unit is used to filter out the high-frequency clutter in the clamped voltage, and its output terminal is connected to the input terminal of the first switching unit; The first switching unit is used to filter out the low-voltage interference signal in the reverse signal, and its output terminal is connected to the input terminal of the current limiting unit. The first switching unit includes a zener diode Z1. The negative electrode of the zener diode Z1 is connected to the output terminal of the filtering unit, and the positive electrode is connected to the input terminal of the current limiting unit; The current limiting unit is used to limit the current of the gating unit and divide the voltage of the control unit, and its output terminal is connected to the input terminal of the second-order filtering unit; The second-order filtering unit is used to smooth the reverse signal after removing the high-voltage signal and high-frequency clutter, and its output terminal is connected to the input terminal of the second switching unit; The second switching unit is used to control the connection between the reverse signal and the vehicle controller.

2. The automotive reverse detection circuit according to claim 1, wherein The filtering unit includes a ferrite bead FB1 and a capacitor C1. One end of the ferrite bead FB1 is connected to the output terminal of the voltage control unit, and the other end is simultaneously connected to one end of the capacitor C1 and the input terminal of the first switching unit. The other end of the capacitor C1 is grounded.

3. The automotive reverse detection circuit according to claim 1, characterized in that, The current limiting unit includes a resistor R2 and a resistor R3 connected in series. One end of the resistor R2 is connected to the output terminal of the first switching unit, and the other end is connected to one end of the resistor R3. The other end of the resistor R3 is grounded.

4. The vehicle reverse detection circuit according to claim 3, wherein, The second-order filtering unit includes a capacitor C2. One end of the capacitor C2 is connected to the series connection node of the resistor R2 and the resistor R3, and the other end is grounded.

5. The automotive reverse detection circuit according to claim 1, wherein The second switching unit includes a triode Q1. The base of the triode Q1 is connected to the output terminal of the second-order filtering unit, the emitter is grounded, and the collector is connected to the signal input terminal of the vehicle controller.

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