Pin switching circuit of OBD interface and vehicle detection device

Abstract

An embodiment of the present application relates to a pin switching circuit for an OBD interface and a vehicle detection device, including a signal on / off module, the signal on / off module is connected to the pins of the OBD interface; a signal bus, the signal bus is connected to the signal on / off module, and the signal on / off module switches between a conducting state and a disconnecting state to control whether a signal is transmitted between the pins of the OBD interface and the signal bus; a channel on / off module, the channel on / off module is connected to the signal bus; and a signal transceiver group, the signal transceiver group is used to receive or send at least one vehicle signal, and the signal transceiver group is connected to the channel on / off module; the channel on / off module switches between a conducting state and a disconnecting state to control whether a signal is transmitted between the signal transceiver group and the signal bus. The present invention can adapt to multiple vehicle fault diagnosis protocols and supports simultaneous communication with the OBD system of a vehicle using multiple different diagnosis protocols.

Description

Technical Field

[0001] The present invention relates to the technical field of vehicle fault diagnosis, and particularly relates to a pin switching circuit for an OBD interface and a vehicle detection device. Background Art

[0002] The On-Board Diagnostics (hereinafter simply referred to as OBD) is a detection system used to monitor whether a vehicle has a fault or excessive exhaust emissions. The on-vehicle diagnostic system connects to the vehicle's electronic control unit ECU (Electronic Control Unit) through various emission-related component information, and the ECU has the function of detecting and analyzing emission-related faults. When an emission fault occurs, the ECU records the fault information and related codes, and issues a warning through the fault light to inform the driver.

[0003] "OBDⅡ" is the abbreviation of "on Board DiagnositicsⅡ", that is, the second-generation on-vehicle diagnostic system. To standardize the diagnosis of vehicle emissions and driveability-related faults, since 1996, all new vehicles sold in the United States must have diagnostic instruments, fault codes, and repair procedures that comply with the OBDⅡ program regulations. With the increasing degree of economic globalization and automotive internationalization, as the basis for driveability and emission diagnosis, the OBDⅡ system will be implemented and applied more and more widely. The vehicle OBD interface, that is, the vehicle diagnostic socket, is the interface for the decoder (vehicle detection device) to connect to the vehicle's ECU vehicle computer. After the vehicle detection device is connected to the vehicle diagnostic socket, it can check whether the vehicle has fault codes and fault records.

[0004] However, the reality is that the diagnostic protocols used by the OBD systems of different vehicle models may be different, and the pins of the OBD interfaces corresponding to the same diagnostic protocol defined by different manufacturers are also not the same. When a vehicle needs to be repaired and diagnosed, it is necessary to first query the pins of the OBD interface corresponding to the diagnostic protocol used by the vehicle manufacturer, which increases the complexity of the work of maintenance personnel. In addition, some old vehicle models use multiple different diagnostic protocols for communication in the OBD system, or multiple different diagnostic protocols are also used in the ECU of the same OBD system. However, the existing OBD diagnostic connectors usually only support communicating with the vehicle's OBD system using one diagnostic protocol transceiver, which brings inconvenience to the diagnosis and repair of vehicles. Summary of the Invention

[0005] Based on this, the present invention provides a pin switching circuit for an OBD interface and a vehicle detection device, which can adapt to multiple vehicle fault diagnosis protocols and provide convenience for the diagnosis and repair of vehicles.

[0006] The present invention is implemented as follows:

[0007] In the first aspect of the embodiments of the present invention, a pin switching circuit for an OBD interface is provided, including:

[0008] A signal on-off module, which is connected to the pins of the OBD interface;

[0009] A signal bus, which is connected to the signal on-off module. The signal on-off module switches between a conducting state and a non-conducting state to control whether a signal is transmitted between the pins of the OBD interface and the signal bus;

[0010] A channel on-off module, which is connected to the signal bus; and

[0011] A signal transceiver group, which is used to receive or transmit at least one vehicle signal. The signal transceiver group is connected to the channel on-off module. The channel on-off module switches between a conducting state and a non-conducting state to control whether a signal is transmitted between the signal transceiver group and the signal bus.

[0012] Further, the signal bus includes a first signal bus and a second signal bus; the channel on-off module is connected to both the first signal bus and the second signal bus;

[0013] The signal on-off module includes a first signal on-off module and a second signal on-off module. The first signal on-off module includes m first controlled switches. The m first controlled switches are respectively connected to m pins of the OBD interface, and each first controlled switch is also connected to the first signal bus. The first controlled switch switches between a conducting state and a non-conducting state. The second signal on-off module includes m second controlled switches. The m second controlled switches are respectively connected to m pins of the OBD interface, and each second controlled switch is also connected to the second signal bus, where m is greater than or equal to 1.

[0014] Further, the signal transceiver group includes n signal transceivers, and each signal transceiver is connected to both the first signal bus and the second signal bus, where n is greater than or equal to 1;

[0015] The channel on-off module includes 2n third controlled switches, and the third controlled switches are connected between the first signal bus and the signal transceiver, and / or the third controlled switches are connected between the second signal bus and the signal transceiver; or the channel on-off module includes n dual-path controlled switches, and the dual-path controlled switches are all connected to the first signal bus and the second signal bus, and the dual-path controlled switches are also connected to the signal transceiver. The dual-path controlled switch switches between a conducting state and a non-conducting state.

[0016] Further, it further includes a terminal resistor loading unit, and the terminal resistor loading unit includes a switch unit and a terminal resistor connected to the switch unit; the terminal resistor loading unit is connected between the signal transceiver group and the channel on-off module, or the terminal resistor loading unit is connected between the channel on-off module and the signal bus;

[0017] The switch unit is used to control the terminal resistor to be connected between the pin of the OBD interface and the signal transceiver group to match the signal transmission impedance.

[0018] Further, the signal transceiver further includes a single-wire CAN transceiver, and the single-wire CAN transceiver is connected to the corresponding pin of the OBD interface through the controlled switch.

[0019] Further, it further includes a multiplexer and a control unit, and the control unit is used to send control signals to at least one of the channel on-off module, the signal on-off module, the terminal resistor loading unit, and the multiplexer;

[0020] The multiplexer is connected to at least one of the signal transceiver group and the single-wire CAN transceiver.

[0021] Further, a first power supply unit, and the first power supply unit includes an OBD power input interface, a first power output terminal, and a buck module. The OBD power input interface is electrically connected to the input terminal of the buck module, and the output terminal of the buck module is electrically connected to the first power output terminal.

[0022] Further, the first power supply unit further includes a first filtering module, a second filtering module, a third filtering module, and a fourth filtering module. The OBD power input interface is electrically connected to the input terminal of the buck module through the first filtering module and the second filtering module in sequence, and the output terminal of the buck module is electrically connected to the first power output terminal through the third filtering module and the fourth filtering module in sequence.

[0023] Further, the first filtering module includes a first capacitor, a second capacitor, a third capacitor, a fourth capacitor, and a fifth capacitor. The first capacitor, the second capacitor, the third capacitor, the fourth capacitor, and the fifth capacitor are all connected between the OBD power input interface and the second filtering module, and both ends of the first capacitor, the second capacitor, the third capacitor, the fourth capacitor, and the fifth capacitor are bridged between the positive and negative poles of the OBD power input interface;

[0024] The second filtering module includes a first common-mode choke. The input end of the first common-mode choke is electrically connected to the output end of the first filtering module, and the output end of the first common-mode choke is electrically connected to the input end of the buck module;

[0025] The third filtering module includes a second common-mode choke. The input end of the second common-mode choke is electrically connected to the output end of the buck module, and the output end of the second common-mode choke is electrically connected to the input end of the fourth filtering module;

[0026] The fourth filtering module includes a sixth capacitor, a seventh capacitor, an eighth capacitor, a ninth capacitor, a tenth capacitor, and an eleventh capacitor. The sixth capacitor, the seventh capacitor, the eighth capacitor, the ninth capacitor, the tenth capacitor, and the eleventh capacitor are all connected between the third filtering module and the first power output terminal, and both ends of the sixth capacitor, the seventh capacitor, the eighth capacitor, the ninth capacitor, the tenth capacitor, and the eleventh capacitor are connected in parallel between the output end of the third filtering module and the ground terminal;

[0027] The OBD power input interface is adapted to be inserted into the OBD connector on the vehicle; the OBD power input interface is used to input a voltage of 12V to 36V to the buck module;

[0028] The buck module is used to convert the voltage from the OBD power input interface into a voltage lower than 12V.

[0029] Further, a second power supply unit is further included; the second power supply unit includes a second power supply voltage input terminal, a second power supply voltage output terminal, and a second power supply control signal input terminal, and the second power supply control signal input terminal is connected to the control unit;

[0030] The second power supply voltage input terminal is connected to the first power output terminal, the second power supply voltage output terminal is electrically connected to the signal transceiver group and / or the multiplexer, and the second power supply voltage output terminal is used to output a first voltage.

[0031] Further, the second power supply unit further includes a first triode, a first MOS transistor, a first resistor, and a first step-down chip. The base of the first triode is electrically connected to the second power supply control signal input terminal. The collector of the first triode is electrically connected to the second power supply voltage input terminal through the first resistor. The collector of the first triode is also electrically connected to the gate of the first MOS transistor. The emitter of the first triode is electrically connected to the ground terminal. The source of the first MOS transistor is electrically connected to the second power supply voltage input terminal. The drain of the first MOS transistor is electrically connected to the input terminal of the first step-down chip. The output terminal of the first step-down chip is electrically connected to the second power supply voltage output terminal.

[0032] Further, a third power supply unit is further included; the third power supply unit includes a third power supply voltage input terminal, a third power supply voltage output terminal, and a third power supply control signal input terminal. The third power supply control signal input terminal is connected to the control unit;

[0033] The third power supply voltage input terminal is connected to the first power supply output terminal. The third power supply voltage output terminal is connected to the signal transceiver group. The third power supply voltage output terminal is used to output a second voltage.

[0034] Further, the third power supply unit further includes a second triode, a second MOS transistor, and a second resistor. The base of the second triode is electrically connected to the third power supply control signal input terminal. The collector of the second triode is electrically connected to the third power supply voltage input terminal through the second resistor. The collector of the second triode is also electrically connected to the gate of the second MOS transistor. The emitter of the second triode is electrically connected to the ground terminal. The source of the second MOS transistor is electrically connected to the third power supply voltage input terminal. The drain of the second MOS transistor is connected to the third power supply voltage output terminal.

[0035] Further, the third power supply unit further includes a third MOS transistor. The gate of the third MOS transistor is electrically connected to the gate of the second MOS transistor. The source of the third MOS transistor is electrically connected to the source of the second MOS transistor. The drain of the third MOS transistor is electrically connected to the drain of the second MOS transistor.

[0036] Further, the third power supply unit further includes a fourth power supply voltage output terminal. The fourth power supply voltage output terminal is connected to the single-wire CAN transceiver and / or the terminal resistance selection unit. The fourth power supply voltage output terminal is used to output a third voltage.

[0037] Further, the third power supply unit further includes a boost chip. The input end of the boost chip is electrically connected to the drain of the second MOS transistor, and the output end of the boost chip is electrically connected to the fourth power voltage output end.

[0038] Further, the controlled switch includes an optocoupler.

[0039] Further, the signal transceiver includes at least one of the following: a general CAN signal transceiver, a high-speed CAN signal transceiver, a medium-speed CAN signal transceiver, and a low-speed CAN signal transceiver.

[0040] Further, it further includes a CAN signal expansion chip; the CAN signal expansion chip is connected to the corresponding general CAN signal transceiver, and the CAN signal expansion chip is used to process the signals sent by the general CAN signal transceiver.

[0041] The second aspect of the embodiments of the present invention provides a vehicle detection device, including an OBD interface; and a pin switching circuit of the OBD interface as described in the first aspect of the embodiments of the present invention, and the OBD interface is connected to the pin switching circuit of the OBD interface.

[0042] For the pin switching circuit of the OBD interface provided by the embodiments of the present invention, the pins of the OBD interface can be connected to a signal transceiver group through a signal bus. The vehicle signals output from the pins of the OBD interface can be transmitted to the signal transceiver group, and the vehicle signals output by the signal transceiver group can also be transmitted to the pins of the OBD interface and then output to the in-vehicle system of the vehicle. And the signal transceiver group can receive or send at least one vehicle signal. Then, the pin switching circuit of the OBD interface in the embodiments of the present invention can receive vehicle signals that conform to different diagnostic protocol specifications, or can also send corresponding vehicle signals that conform to different diagnostic protocol specifications to different in-vehicle systems. Thus, the pin switching circuit of the OBD interface in the embodiments of the present invention can realize the diagnosis and detection of vehicles using different diagnostic protocols. In addition, both the signal on-off module and the channel on-off module can switch between the on or off states. By controlling the on or off states of one or both of the above, according to different requirements of detection or diagnosis, any type of vehicle signal can be input or not input to the signal transceiver group, or the vehicle signals of the signal transceiver group can be output or not output to the pins, enhancing the convenience of diagnosis or detection.

[0043] In another embodiment of the present invention, the pin switching circuit may further include multiple pairs of signal buses. Multiple signal transceivers can communicate with different vehicle OBD systems through the multiple pairs of signal buses, or multiple signal transceivers can communicate with multiple electronic control units applying different diagnostic protocols on the same vehicle through the multiple pairs of signal buses. Moreover, the communication transmission lines corresponding to each signal transceiver do not interfere with each other, which provides convenience for vehicle diagnosis and repair.

[0044] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the drawings in the following description are only some embodiments of the present application. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] Figure 1 It is a layout schematic diagram of the pins of the OBD interface in the traditional technology;

[0046] Figure 2 It is a structural schematic diagram of a pin switching circuit of an OBD interface provided by the present invention;

[0047] Figure 3 It is a structural schematic diagram of a terminal resistance selection unit of a pin switching circuit of an OBD interface provided by the present invention;

[0048] Figure 4 It is a circuit schematic diagram of a first power supply unit of a pin switching circuit of an OBD interface provided by the present invention;

[0049] Figure 5 It is a circuit schematic diagram of a second power supply unit of a pin switching circuit of an OBD interface provided by the present invention;

[0050] Figure 6 It is a circuit schematic diagram of a second power supply unit of a pin switching circuit of an OBD interface provided by the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0051] To make the objectives, technical solutions, and advantages of the present application clearer, the following will further describe the embodiments of the present application in detail in conjunction with the drawings.

[0052] It should be clear that the described embodiments are only a part of the embodiments of the present application, rather than all of the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments in the present application without creative efforts belong to the scope protected by the embodiments of the present application.

[0053] The terms used in the embodiments of the present application are for the purpose of describing specific embodiments only and are not intended to limit the embodiments of the present application. The singular forms "a", "the", and "said" used in the embodiments of the present application and the appended claims are also intended to include the plural forms unless the context clearly dictates otherwise. It should also be understood that the term "and / or" as used herein refers to and encompasses any and all possible combinations of one or more of the associated listed items.

[0054] When the following description refers to the accompanying drawings, unless otherwise indicated, the same numbers in different drawings represent the same or similar elements. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with the present application. On the contrary, they are merely examples of devices and methods consistent with some aspects of the present application as detailed in the appended claims. In the description of the present application, it should be understood that the terms "first", "second", "third", etc. are only used to distinguish similar objects and do not have to be used to describe a specific order or sequence, nor should they be construed as indicating or implying relative importance. For those of ordinary skill in the art, the specific meanings of the above terms in the present application can be understood according to specific circumstances.

[0055] In addition, in the description of the present application, unless otherwise specified, "a plurality of" means two or more. "And / or" describes the association relationship of associated objects and indicates that three relationships can exist. For example, A and / or B can represent: A exists alone, A and B exist simultaneously, and B exists alone. The character " / " generally represents an "or" relationship between the associated objects before and after.

[0056] As Figure 1 shown, Figure 1 FIG. 13 is a schematic layout diagram of the pins of the OBD interface in the prior art, where the pins 1, 3, 6, 8, 9, 11, 12, 13, and 14 can be customized according to the actual situation of the manufacturer; the pin 2 is the positive pole of the SAE J1850 signal bus; the pin 10 is the negative pole of the SAE J1850 signal bus; the pin 4 is the chassis ground; the pin 5 is the signal ground; the pin 7 is the K line; the pin 15 is the L line; the pin 16 is the positive pole of the constant power supply.

[0057] The present invention provides a pin switching circuit for an OBD interface, which is applied to a vehicle detection device. The vehicle diagnostic device includes a housing with an interface hole on it, and an OBD interface is arranged inside the interface hole. The vehicle detection device is connected to an automotive diagnostic socket through the OBD interface, and the vehicle detection device communicates with the in-vehicle system of the vehicle through a specific diagnostic protocol. The vehicle detection device can obtain fault codes and fault records of the vehicle from the automotive diagnostic socket. In some embodiments, the vehicle detection device can also provide a fault code query function, or the vehicle detection device can also be signal-connected to intelligent terminals such as mobile phones and tablets, and under the remote control of the intelligent terminal, the above functions can be realized, and the obtained diagnostic data can be sent to the intelligent terminal.

[0058] As Figure 2 shown, Figure 2 FIG. is a schematic structural diagram of a pin switching circuit for an OBD interface provided by an embodiment of the present invention. The pin switching circuit includes a signal transceiver group, a channel on / off module, a first signal on / off module, a second signal on / off module, a first signal bus 146, a second signal bus 132, a terminal resistor selection unit U22, a multiplexing module, a control unit A, a first power supply unit 50, a second power supply unit 30, and a third power supply unit 40.

[0059] Specifically, the signal transceiver group includes n signal transceivers. In Figure 2 , the signal transceiver group includes 5 signal transceivers. Among them, the signal transceiver can receive / send vehicle data that conforms to the preset vehicle diagnostic protocol specification. Through the pins of the OBD interface, the pin switching circuit can read the diagnostic information of the automotive electronic control unit (ECU), or the pin switching circuit can write configuration or parameter information to the automotive diagnostic socket. Each signal transceiver is connected to its corresponding channel, and each channel includes two signal lines, namely a high level and a low level. In the embodiment of the present invention, taking the high-speed CAN transceiver U26 as an example, its two signal lines are respectively connected to the first signal bus 146 and the second signal bus 132; and through the first signal bus 146 and the second signal bus 132, it can be connected to the pins on the corresponding OBD interface 10. In addition, there is also a single-wire CAN transceiver U24. Among them, the single-wire CAN transceiver U24 is not connected to the signal bus and is directly connected to the pins of the corresponding OBD interface 10. In Figure 2 , the single-wire CAN transceiver U24 is specifically connected to pin 1.

[0060] In the embodiments of the present invention, the type and quantity of the signal transceiver are not limited. In some other embodiments, the above-mentioned signal transceiver includes but is not limited to: high-speed CAN signal transceiver, medium-speed CAN signal transceiver, low-speed / fault-tolerant CAN signal transceiver, Kwp protocol transceiver (ISO14230), SAE J1708 protocol transceiver, SAE J1850-PWM protocol transceiver, SAE J1850-VPW protocol transceiver, FlexRay protocol transceiver, SAE J2284 protocol transceiver, ISO 9141Ford protocol transceiver, UART Protocol protocol transceiver, ISO 9141-2 protocol transceiver, CARB UART Protocol protocol transceiver, DCL UART protocol transceiver, UBP protocol transceiver, DDL UART protocol transceiver, SCP protocol transceiver, SCI protocol transceiver, General Motors (GM) 8192 protocol transceiver, etc.

[0061] The channel on / off module is used to control the connection between the channel of each signal transceiver and the first signal bus 146 and the second signal bus 132. In Figure 2 the example, the channel on / off module is specifically a plurality of double-relays, specifically including relay K51, relay K53, relay K55, relay K57, and relay K59. Among them, each double-relay separately controls the on / off of the channel of the corresponding signal transceiver and the signal bus. In other examples, the channel on / off module may further include 2n third controlled switches, and a pair of third controlled switches are used to respectively control the on / off of the corresponding first signal line or the second signal line. Or rather, the channel on / off module may also be composed of a combination of third controlled switches and relays.

[0062] In the embodiments of the present invention, each pin of the OBD interface 10 is connected to the first signal bus 146 through the first signal on / off module, and each pin of the OBD interface 10 is also connected to the second signal bus 132 through the second signal on / off module. Among them, the first signal on / off module can respectively control the on / off of the connection between each pin of the OBD interface 10 and the first signal bus 146, and the second signal on / off module can respectively control the on / off of the connection between each pin of the OBD interface 10 and the second signal bus 132.

[0063] Specifically, the first signal on / off module includes m first controlled switches, which respectively control the on / off of the corresponding m pins of the OBD interface and the first signal bus 146. The second signal on / off module also includes m second controlled switches, which respectively control the on / off of the corresponding m pins of the OBD interface and the second signal bus 132, where m is greater than 1.

[0064] InFigure 2 In the example, the first controlled switch of the first signal on-off module is specifically the optocoupler 21, and the second controlled switch of the second signal on-off module is specifically the optocoupler 22. Additionally, the single-wire CAN transceiver U24 is connected to the corresponding pin 1 of the OBD interface 10 through the fourth controlled switch. In Figure 2 , the fourth controlled switch is specifically an optocoupler. The optocoupler can not only be electrically controlled, but also has the characteristics of mutual isolation between input and output, unidirectional transmission of electrical signals, etc., thus having good electrical insulation ability and anti-interference ability. In other examples, the first and second controlled switches can also be relays, switch chips, etc.

[0065] In the embodiment of the present invention, the signal buses are described by taking the first signal bus 146 and the second signal bus 132 as CAN signal buses respectively. In some other examples, the types of signal buses include but are not limited to CAN signal buses, LIN signal buses, and VAN signal buses, which can be determined according to the specific diagnostic protocol transmitted in the line.

[0066] In some preferred embodiments, the number of signal buses can also be more than two, and the signal on-off modules can also be more than two. There can be more than two on-off modules corresponding to more than two signal buses, so as to realize the signal transmission of more diagnostic protocols.

[0067] In Figure 2 , the terminal resistor loading unit U22 is also respectively connected to the channels of the ordinary CAN signal transceiver U20, the ordinary CAN signal transceiver U21, the ordinary CAN signal transceiver U23, and the high-speed CAN signal transceiver U26. The terminal resistor loading unit U22 can control to connect the two ends of the terminal resistor across the two transmission lines of the corresponding channel. Additionally, the two ends of the terminal resistor can be controlled to be connected across the two transmission lines in the channel of the low-speed CAN transceiver U26 through the relay K1.

[0068] Specifically, the signal transceiver includes two signal lines for transmitting vehicle signals. These two signal lines are connected to two signal buses one by one, or each of these two signal lines can be connected to two signal buses one by one through a third controlled switch or a dual-channel controlled switch. After the in-vehicle system of the vehicle outputs the vehicle signal to the pin switching circuit of the embodiment of the present invention, the pins of the OBD interface can output the vehicle signal to the signal transceiver via the first controlled switch, the second controlled switch, the signal bus, and the third controlled switch, and vice versa. During this process, when the vehicle signal is output from one of the signal transceivers to the pins of the OBD interface, or when the vehicle signal is output from the pins of the OBD interface to one of the signal transceivers, the transmission lines through which the vehicle signal passes, and the pins of the OBD interface, the first controlled switch, the second controlled switch, the third controlled switch, the signal transceiver, etc. distributed on these transmission lines will form a channel. Among them, each channel includes two signal transmission lines.

[0069] Specifically, as Figure 3 shown, Figure 3 FIG. shows the circuit structure diagram of the termination resistor loading unit. The termination resistor loading unit U22 includes a switch chip KN1 and a plurality of termination resistors connected thereto. The number of termination resistors is the same as the number of signal transceivers they are connected to. The switch chip KN1 includes a plurality of sub-switch circuits, and each sub-switch circuit includes two input / output terminals. Optionally, in each sub-switch circuit, one of the input / output terminals is connected to the termination resistor, the termination resistor is also connected to one of the transmission lines of one of the channels, and the other input / output terminal is connected to the other transmission line of the same channel.

[0070] After the sub-switch circuit is turned on, the two ends of the termination resistor connected to the sub-switch circuit are sequentially connected to the two transmission lines in the channel connected to the sub-switch circuit. Thus, the termination resistor can absorb signal reflections and echoes, eliminate interference during signal transmission, achieve impedance matching of the channel, and improve the anti-interference performance and reliability of signal transmission.

[0071] In this embodiment, the ordinary CAN transceivers U20, U21, U23, the high-speed CAN transceiver U26 are connected to the terminal resistor loading unit U22. The terminal resistor loading unit U22 is also respectively connected to the relays K53, K55, K57 and K59. In order to achieve normal diagnostic communication (usually communication based on the CAN protocol), the terminal resistor loading unit U22 can connect a terminal resistor to the two communication lines of the channel where the above transceivers are located to achieve normal communication. When the diagnostic device applies the pin switching circuit of this embodiment, the switch chip KN1 is switched to the closed or conducting state, and the two ends of the terminal resistor can be respectively connected to the two transmission lines of the corresponding channel, meeting the requirements for the physical layer bus in the diagnostic protocol specification. If the other circuits of the diagnostic device have a terminal resistor, the switch chip KN1 can be switched to the open state, and the terminal resistor is not connected to the corresponding channel. The terminal resistor loading unit U22 enables the OBD pin switching circuit described in this embodiment to adapt to various diagnostic devices.

[0072] As Figure 2 described, the channels of the low-speed CAN transceiver U25 are respectively connected to the first signal bus 146 and the second signal bus 132 through the relay K51. The terminal resistor loading unit U22 also includes a relay K1 and a terminal resistor connected to the relay K1. The relay includes two input / output terminals, one of which is connected to one end of the terminal resistor (not shown in the figure), the other end of the terminal resistor is connected to one of the transmission lines in the channel where the low-speed CAN transceiver U25 is located, and the other input / output terminal is connected to the other transmission line in the channel where the low-speed CAN transceiver U25 is located. By controlling the switching of the relay K1 between the conducting and non-conducting states, it can be controlled whether the terminal resistor is connected between the two transmission lines of the channel where the low-speed CAN transceiver U25 is located, so as to control whether to implement the impedance matching function of the channel where the low-speed CAN transceiver U25 is located.

[0073] As Figure 2 shown, in this embodiment, it further includes a CAN signal expansion chip U16 and a CAN signal expansion chip U18; the CAN signal expansion chip U16 is connected to the ordinary CAN signal transceiver U20, and the CAN signal expansion chip U18 is connected to the ordinary CAN signal transceiver U21.

[0074] In Figure 2 it, the multiplexing module includes a multiplexer U17 and a multiplexer U19. The multiplexer U17 is connected to the ordinary CAN transceiver U23 and the single-wire CAN transceiver U24, and the multiplexer U19 is connected to the high-speed CAN transceiver U26 and the low-speed CAN transceiver U25.

[0075] The multiplexer U17 and the multiplexer U19 are also respectively connected to the control unit A, and the CAN signal extension chip U16 and the CAN signal extension chip U18 are also respectively connected to the control unit A.

[0076] The control unit A serves as the control core of the vehicle detection device, and is used to drive the signal transceiver in the above embodiments to communicate with the in-vehicle system on the vehicle, and obtain the vehicle fault diagnosis code from the ECU of the vehicle. In this embodiment, the control unit A is also used to drive the on-off of components such as the above-mentioned switch chip KN1, optocoupler, and relay. The control unit A can also output control signals to the relay and optocoupler through an FPGA, register, latch, etc. The control unit A includes, but is not limited to, one or any combination of an MCU, MPU, DPU, CPU, ASIC, etc.

[0077] The pin switching circuit of the present invention further includes a first power supply unit 50, a second power supply unit 30, and a third power supply unit 40, as Figure 2 shown, the first power supply unit 50 includes an OBD power input interface 51, a first power output terminal 52, and a buck module U1. The OBD power input interface 51 is electrically connected to the input terminal of the buck module U1, and the output terminal of the buck module U1 is electrically connected to the first power output terminal 52. The OBD power input interface 51 can be inserted into the OBD connector on an automobile or a truck and input a voltage of 12V or 24V. The buck module U1 is used to step down the voltage from the OBD power input interface 51 to 5V. The first power supply unit 50 is used to output a 5V regulated power supply to the second power supply unit 30 and the third power supply unit 40.

[0078] The first power supply unit 50 further includes a first filtering module 53, a second filtering module 54, a third filtering module 55, and a fourth filtering module 56. The OBD power input interface 51 is electrically connected to the input terminal of the buck module U1 through the first filtering module 53 and the second filtering module 54 in sequence, and the output terminal of the buck module U1 is electrically connected to the first power output terminal 52 through the third filtering module 55 and the fourth filtering module 56 in sequence.

[0079] Specifically, as Figure 2 and Figure 4 shown, the first filtering module 53 includes a first capacitor C2, a second capacitor C3, a third capacitor C6, a fourth capacitor C7, and a fifth capacitor C8; the first capacitor C2, the second capacitor C3, the third capacitor C6, the fourth capacitor C7, and the fifth capacitor C8 are all connected between the OBD power input interface 51 and the second filtering module 54, and both ends of the first capacitor C2, the second capacitor C3, the third capacitor C6, the fourth capacitor C7, and the fifth capacitor C8 are connected across the positive and negative poles of the OBD power input interface 51.

[0080] The second filtering module 54 includes a first common-mode choke L2. The input end of the first common-mode choke L2 is electrically connected to the output end of the first filtering module 53, and the output end of the first common-mode choke L2 is electrically connected to the input end of the buck module U1.

[0081] The third filtering module 55 includes a second common-mode choke L1. The input end of the second common-mode choke L1 is electrically connected to the output end of the buck module U1, and the output end of the second common-mode choke L1 is electrically connected to the input end of the fourth filtering module 56.

[0082] The fourth filtering module 56 includes a sixth capacitor C12, a seventh capacitor C13, an eighth capacitor C14, a ninth capacitor C15, a tenth capacitor C16, and an eleventh capacitor C17. The sixth capacitor C12, the seventh capacitor C13, the eighth capacitor C14, the ninth capacitor C15, the tenth capacitor C16, and the eleventh capacitor C17 are all connected between the third filtering module 55 and the first power output terminal 52, and both ends of the sixth capacitor C12, the seventh capacitor C13, the eighth capacitor C14, the ninth capacitor C15, the tenth capacitor C16, and the eleventh capacitor C17 are connected in parallel between the output end of the third filtering module 55 and the ground terminal.

[0083] As Figure 2 shown, the second power supply unit 30 includes a second power supply voltage input terminal 31, a second power supply voltage output terminal 33, and a second power supply control signal input terminal 32. Among them, the second power supply control signal input terminal 32 is connected to the control unit A.

[0084] The second power supply voltage input terminal 31 is connected to the first power output terminal 52. In Figure 2 it, the second power supply voltage output terminal 33 is used to output a first voltage. Optionally, the second power supply voltage output terminal 33 is used to output a 3.3V voltage. The second power supply voltage output terminal 33 is electrically connected to the CAN signal expansion chips U16, U18, the CAN signal expansion chip U17, and the multiplexer U19, and supplies power to the above-mentioned components.

[0085] As Figure 2 and Figure 5As shown, the second power supply unit 30 further includes a first triode Q3, a first MOS transistor Q2, a first resistor R41, a resistor R42, and a first step-down chip U11. The base of the first triode Q3 is electrically connected to the second power supply control signal input terminal 32. The collector of the first triode Q3 is electrically connected to the second power supply voltage input terminal 31 through the first resistor R41 and the resistor R42. The collector of the first triode Q3 is also electrically connected to the gate of the first MOS transistor Q2 through the resistor R42. The emitter of the first triode Q3 is electrically connected to the ground terminal. The source of the first MOS transistor Q2 is electrically connected to the first power supply voltage input terminal 31. The drain of the first MOS transistor Q2 is electrically connected to the input terminal of the first step-down chip U11. The output terminal of the first step-down chip U11 is electrically connected to the second power supply voltage output terminal 33.

[0086] In an embodiment of the present invention, the second power supply control signal input terminal 32 outputs a high level or a low level by a GPIO port of the control unit A, and controls whether the second power supply unit 30 outputs voltage by controlling the first MOS transistor Q2 and the first triode Q3. When the second power supply control signal input terminal 32 is at a high level, the emitter and the collector of the first triode Q3 are turned on, so that the source and the drain of the first MOS transistor Q2 are turned on, and the second power supply voltage output terminal 33 outputs a 5V voltage. When the second power supply control signal input terminal 32 is at a low level, the first triode Q3 is turned off, so that the first MOS transistor Q2 is turned off, and the second power supply voltage output terminal 33 stops outputting a 5V voltage.

[0087] As Figure 2 shown, the third power supply unit 40 includes a third power supply voltage input terminal 41, a third power supply voltage output terminal 43, and a third power supply control signal input terminal 42. The third power supply control signal input terminal 42 is connected to the control unit A.

[0088] The third power supply voltage input terminal 41 is connected to the first power supply output terminal 52. The third power supply voltage output terminal 43 is used to output a second voltage. Optionally, the third power supply voltage output terminal 43 is used to output a 5V voltage. The third power supply voltage output terminal 43 is connected to the ordinary CAN signal transceivers U20, U21, U23, and the high-speed CAN signal transceiver U26 and the low-speed CAN signal transceiver U25, and provides power for the above-mentioned components.

[0089] As Figure 2 and Figure 6As shown, the third power supply unit 40 further includes a second triode Q5, a second MOS transistor Q4, and a second resistor R46. The base of the second triode Q5 is electrically connected to the third power supply control signal input terminal 42. The collector of the second triode Q5 is electrically connected to the third power supply voltage input terminal 41 through the second resistor R46. The collector of the second triode Q5 is also electrically connected to the gate of the second MOS transistor Q4. The emitter of the second triode Q5 is electrically connected to the ground terminal. The source of the second MOS transistor Q6 is electrically connected to the third power supply voltage input terminal 41. The drain of the second MOS transistor Q4 is connected to the third power supply voltage output terminal 43.

[0090] Preferably, in order to increase the redundancy of the third power supply unit 40, the third power supply unit 40 further includes a third MOS transistor Q6 connected to the second MOS transistor Q4. The gate of the third MOS transistor Q6 is electrically connected to the gate of the second MOS transistor Q5. The source of the third MOS transistor Q6 is electrically connected to the source of the second MOS transistor Q5. The drain of the third MOS transistor Q6 is electrically connected to the drain of the second MOS transistor Q5.

[0091] The third power supply unit 40 further includes a fourth power supply voltage output terminal 44. The fourth power supply voltage output terminal 44 is connected to the single-wire CAN transceiver U24 and the terminal resistor selection unit U22. The fourth power supply voltage output terminal 44 is used to output an 8V voltage.

[0092] The third power supply unit 40 further includes a boost chip U12. The input terminal of the boost chip U12 is electrically connected to the drain of the second MOS transistor Q5. The output terminal of the boost chip U12 is electrically connected to the fourth power supply voltage output terminal 44.

[0093] In the embodiment of the present invention, the third power supply control signal input terminal 42 is also controlled by a GPIO port of the control unit A to output a high level or a low level. By controlling the first triode Q5, the second MOS transistor Q4, and the third MOS transistor Q6, it is possible to control whether the third power supply voltage output terminal 43 and the fourth power supply voltage output terminal 44 of the third power supply unit 40 output voltage. When the third power supply control signal input terminal 42 is at a high level, the emitter and collector of the second triode Q5 are turned on, causing the source and drain of the second MOS transistor Q4 to be turned on and the source and drain of the third MOS transistor Q6 to be turned on. The third power supply voltage output terminal 43 outputs a 5V voltage, and the fourth power supply voltage output terminal 44 outputs an 8V voltage. When the third power supply control signal input terminal 42 is at a low level, the second triode Q5 is turned off, causing the second MOS transistor Q4 and the third MOS transistor Q6 to be turned off. The third power supply voltage output terminal 43 stops outputting a 5V voltage, and the fourth power supply voltage output terminal 44 stops outputting an 8V voltage.

[0094] Taking pin 11 and pin 3 as examples, the working principle of the pin switching circuit of the OBD interface according to the embodiment of the present invention is introduced as follows: The control unit A controls the optical coupler 22 connected between pin 11 and the second signal bus 132 to conduct, and the optical coupler 21 connected between pin 3 and the first signal bus 146 to conduct, and the relay K53 to conduct, so as to control the U22 terminal resistance selection unit to access the terminal resistance in parallel with the K53 relay and the U26 high-speed CAN transceiver. The electrical signals of pin 11 and pin 3 can be transmitted to the multiplexer U19 along the channels connecting the relay K53, the U22 terminal resistance selection unit, and the U26 high-speed CAN transceiver, and then transmitted to the control unit A.

[0095] In a specific application scenario, if three different diagnostic protocols are applied to the in-vehicle OBD system of a vehicle, in order to communicate with the in-vehicle OBD system for data reading and writing, the diagnostic device needs to support communication with the in-vehicle OBD system using these three or more different diagnostic protocols, or support simultaneous communication with the in-vehicle OBD system using multiple different diagnostic protocols. Usually, two signal lines are used for one diagnostic protocol, so six signal lines are usually required for three different diagnostic protocols. Therefore, the K1 relay and the optical coupler in the embodiment of the present invention can conduct the corresponding diagnostic signal channels according to the needs of diagnosis, and the OBD pins used for each diagnostic signal channel are different. Taking the simultaneous transmission of three diagnostic signals as an example, among the six signal lines of the three diagnostic signals, the transmission of multiple diagnostic signals can be achieved when no two or more lines use the same OBD pin.

[0096] If it is necessary to achieve simultaneous communication on 3 channels, the 6 pins corresponding to the 3 diagnostic protocols in the OBD interface should not occupy each other. After meeting the above conditions, the optical couplers of the 6 lines of the 3 diagnostic protocols are conducted or the corresponding relay K1 is conducted, and the 3 diagnostic signals can then enter the signal transceiver for processing, and the signal transceiver sends the processed signals to the control unit.

[0097] Corresponding to the above pin switching circuit of an OBD interface, an embodiment of the present application further provides a vehicle detection device, including a housing, an interface hole formed on the housing, an OBD interface provided in the interface hole, and an OBD interface pin switching circuit as described in any one of the above embodiments provided in the housing.

[0098] An OBD interface pin switching circuit provided by an embodiment of the present invention controls a controlled switch by setting two or more signal on / off modules to control the connection between a signal bus and an OBD interface pin, enabling any signal transceiver to access a corresponding pin through the signal bus and further communicate with an on-vehicle diagnostic system of a vehicle; and arbitrarily switching the connection between the pins on the OBD interface and one or more signal transceivers, so that the OBD pin switching circuit of the embodiment of the present invention can adapt to multiple vehicle fault diagnosis protocols. In other optional embodiments, the OBD interface pin switching circuit of the embodiment of the present invention can also receive / send / process various diagnostic data conforming to different diagnostic protocols, so as to communicate with on-vehicle OBD systems of different or the same vehicle using different diagnostic protocols.

[0099] It should be understood that the embodiments of the present application are not limited to the exact structures already described and shown in the drawings, and various modifications and changes can be made without departing from its scope. The scope of the embodiments of the present application is only limited by the appended claims.

[0100] The above-described embodiments only represent several implementation manners of the embodiments of the present application. The description is relatively specific and detailed, but it should not be construed as a limitation on the scope of the invention patent. It should be noted that for those of ordinary skill in the art, without departing from the concept of the embodiments of the present application, several deformations and improvements can still be made, and these all belong to the protection scope of the embodiments of the present application.

Claims

1. A pin switching circuit for an OBD interface, characterized in that, Comprising: A signal on-off module, which is connected to the pins of the OBD interface; A signal bus, which is connected to the signal on-off module. The signal on-off module switches between a conducting state and a non-conducting state to control whether a signal is transmitted between the pins of the OBD interface and the signal bus; A channel on-off module, which is connected to the signal bus; And A signal transceiver group, which is used to receive or transmit at least one vehicle signal. The signal transceiver group is connected to the channel on-off module. The channel on-off module switches between a conducting state and a non-conducting state to control whether a signal is transmitted between the signal transceiver group and the signal bus; The signal bus includes a first signal bus and a second signal bus; the channel on-off module is connected to both the first signal bus and the second signal bus; The signal on-off module includes a first signal on-off module and a second signal on-off module. The first signal on-off module includes m first controlled switches. The m first controlled switches are respectively connected to the m pins of the OBD interface, and each first controlled switch is also connected to the first signal bus. The first controlled switch switches between a conducting state and a non-conducting state; the second signal on-off module includes m second controlled switches. The m second controlled switches are respectively connected to the m pins of the OBD interface, and each second controlled switch is also connected to the second signal bus, where m is greater than or equal to 1; The signal transceiver group includes n signal transceivers, and each signal transceiver is connected to both the first signal bus and the second signal bus, where n is greater than or equal to 1; The channel on-off module includes 2n third controlled switches. n of the third controlled switches are connected between the first signal bus and the signal transceiver, and / or another n of the third controlled switches are connected between the second signal bus and the signal transceiver; It further includes a terminal resistance loading unit, which includes a switch unit and a terminal resistance connected to the switch unit; A first power supply unit, which includes an OBD power input interface, a first power output terminal, a buck module, a first filtering module, a second filtering module, a third filtering module, and a fourth filtering module; the OBD power input interface is electrically connected to the input terminal of the buck module through the first filtering module and the second filtering module in sequence, and the output terminal of the buck module is electrically connected to the first power output terminal through the third filtering module and the fourth filtering module in sequence.

2. The pin switching circuit of the OBD interface according to claim 1, wherein: Or the channel on-off module includes n dual-channel controlled switches. The dual-channel controlled switches are all connected to the first signal bus and the second signal bus, and the dual-channel controlled switches are also connected to the signal transceiver. The dual-channel controlled switches switch between a conducting state and a non-conducting state.

3. The pin switching circuit of the OBD interface according to claim 1, wherein: The terminal resistor loading unit is connected between the signal transceiver group and the channel on-off module, or the terminal resistor loading unit is connected between the channel on-off module and the signal bus; The switch unit is used to control the connection of the terminal resistor between the pin of the OBD interface and the signal transceiver group to match the signal transmission impedance.

4. The pin switching circuit of the OBD interface according to claim 3, wherein: The signal transceiver further includes a single-wire CAN transceiver, and the single-wire CAN transceiver is connected to the corresponding pin of the OBD interface through a controlled switch.

5. The pin switching circuit of the OBD interface according to claim 4, wherein: It further includes a multiplexer and a control unit, and the control unit is used to send control signals to at least one of the channel on-off module, the signal on-off module, the terminal resistor loading unit, and the multiplexer; The multiplexer is connected to at least one of the signal transceiver group and the single-wire CAN transceiver.

6. The pin switching circuit of the OBD interface according to claim 5, wherein: The first filtering module includes a first capacitor, a second capacitor, a third capacitor, a fourth capacitor, and a fifth capacitor. The first capacitor, the second capacitor, the third capacitor, the fourth capacitor, and the fifth capacitor are all connected between the OBD power input interface and the second filtering module, and both ends of the first capacitor, the second capacitor, the third capacitor, the fourth capacitor, and the fifth capacitor are connected across the positive and negative poles of the OBD power input interface; The second filtering module includes a first common-mode choke. The input end of the first common-mode choke is electrically connected to the output end of the first filtering module, and the output end of the first common-mode choke is electrically connected to the input end of the buck module; The third filtering module includes a second common-mode choke. The input end of the second common-mode choke is electrically connected to the output end of the buck module, and the output end of the second common-mode choke is electrically connected to the input end of the fourth filtering module; The fourth filtering module includes a sixth capacitor, a seventh capacitor, an eighth capacitor, a ninth capacitor, a tenth capacitor, and an eleventh capacitor. The sixth capacitor, the seventh capacitor, the eighth capacitor, the ninth capacitor, the tenth capacitor, and the eleventh capacitor are all connected between the third filtering module and the first power output end, and both ends of the sixth capacitor, the seventh capacitor, the eighth capacitor, the ninth capacitor, the tenth capacitor, and the eleventh capacitor are connected in parallel between the output end of the third filtering module and the ground terminal; The OBD power input interface is adapted to be inserted into the OBD connector on the vehicle; the OBD power input interface is used to input a voltage of 12V to 36V to the buck module; The buck module is used to convert the voltage from the OBD power input interface into a voltage lower than 12V.

7. The pin switching circuit of the OBD interface according to claim 5, wherein: It further includes a second power supply unit; the second power supply unit includes a second power supply voltage input terminal, a second power supply voltage output terminal, and a second power supply control signal input terminal, and the second power supply control signal input terminal is connected to the control unit; The second power supply voltage input terminal is connected to the first power supply output terminal, the second power supply voltage output terminal is electrically connected to the signal transceiver group and / or the multiplexer, and the second power supply voltage output terminal is used to output a first voltage.

8. The pin switching circuit of an OBD interface according to claim 7, wherein: The second power supply unit further includes a first triode, a first MOS transistor, a first resistor, and a first step-down chip. The base of the first triode is electrically connected to the second power supply control signal input terminal. The collector of the first triode is electrically connected to the second power supply voltage input terminal through the first resistor. The collector of the first triode is also electrically connected to the gate of the first MOS transistor. The emitter of the first triode is electrically connected to the ground terminal. The source of the first MOS transistor is electrically connected to the second power supply voltage input terminal. The drain of the first MOS transistor is electrically connected to the input terminal of the first step-down chip. The output terminal of the first step-down chip is electrically connected to the second power supply voltage output terminal.

9. The pin switching circuit of an OBD interface according to claim 5, wherein: It further includes a third power supply unit; the third power supply unit includes a third power supply voltage input terminal, a third power supply voltage output terminal, and a third power supply control signal input terminal, and the third power supply control signal input terminal is connected to the control unit; The third power supply voltage input terminal is connected to the first power supply output terminal, the third power supply voltage output terminal is connected to the signal transceiver group, and the third power supply voltage output terminal is used to output a second voltage.

10. The pin switching circuit of an OBD interface according to claim 9, wherein: The third power supply unit further includes a second triode, a second MOS transistor, and a second resistor. The base of the second triode is electrically connected to the third power supply control signal input terminal. The collector of the second triode is electrically connected to the third power supply voltage input terminal through the second resistor. The collector of the second triode is also electrically connected to the gate of the second MOS transistor. The emitter of the second triode is electrically connected to the ground terminal. The source of the second MOS transistor is electrically connected to the third power supply voltage input terminal. The drain of the second MOS transistor is connected to the third power supply voltage output terminal.

11. The pin switching circuit of an OBD interface according to claim 10, wherein: The third power supply unit further includes a third MOS transistor. The gate of the third MOS transistor is electrically connected to the gate of the second MOS transistor. The source of the third MOS transistor is electrically connected to the source of the second MOS transistor. The drain of the third MOS transistor is electrically connected to the drain of the second MOS transistor.

12. The pin switching circuit of an OBD interface according to claim 11, wherein: The third power supply unit further includes a fourth power voltage output terminal, which is connected to the single-wire CAN transceiver and / or the terminal resistor selection unit, and the fourth power voltage output terminal is used to output a third voltage.

13. The pin switching circuit of an OBD interface according to claim 12, wherein: The third power supply unit further includes a boost chip, the input end of the boost chip is electrically connected to the drain of the second MOS transistor, and the output end of the boost chip is electrically connected to the fourth power voltage output terminal.

14. The pin switching circuit of an OBD interface according to any one of claims 1-13, wherein: The controlled switch includes an optocoupler.

15. The pin switching circuit of an OBD interface according to any one of claims 1-13, wherein: The signal transceiver includes at least one of the following: a normal CAN signal transceiver, a high-speed CAN signal transceiver, a medium-speed CAN signal transceiver, and a low-speed CAN signal transceiver.

16. The pin switching circuit of an OBD interface according to claim 15, wherein: It further includes a CAN signal expansion chip; the CAN signal expansion chip is connected to the corresponding normal CAN signal transceiver, and the CAN signal expansion chip is used to process the signals sent by the normal CAN signal transceiver.

17. A vehicle detection device, wherein: An OBD interface; And The pin switching circuit of an OBD interface according to any one of claims 1-16, and the OBD interface is connected to the pin switching circuit of the OBD interface.

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