A switching circuit for dual fuel injectors and a vehicle

Abstract

This application provides a switching circuit and vehicle for dual-fuel injectors. The switching circuit includes at least one set of logic control circuits; each set of logic control circuits includes a first switching circuit, a second switching circuit, and a third switching circuit; the first switching circuit receives a control signal and controls the second switching circuit to conduct when the control signal is at a first level; the third switching circuit conducts when the control signal is at a second level; the second switching circuit connects a power supply voltage to the first injector when it is conducting; the third switching circuit connects the power supply voltage to the second injector when it is conducting. By setting a circuit to control the switching of injectors for two different fuels, and the circuit including three switching circuits, and the first switching circuit controlling the conduction and deactivation of the second or third switching circuit according to the two levels of the control signal, the switching of the two injectors is realized.

Description

Technical Field

[0001] This application relates to the field of electronics and electrical appliances, and more particularly to a switching circuit for a dual-fuel nozzle and a vehicle. Background Technology

[0002] In the automotive field, current mature engine controllers only have one set of fuel injector drive circuits, which cannot meet the needs of controlling two sets of injectors. Summary of the Invention

[0003] In a first aspect, embodiments of this application provide a switching circuit for a dual-fuel nozzle, comprising: at least one set of logic control circuits; each set of logic control circuits is used to control the switching of two nozzles using different fuels; each set of logic control circuits includes: a first switching circuit, a second switching circuit, and a third switching circuit, wherein: the first switching circuit is used to receive a control signal, and when the control signal is at a first level, controls the second switching circuit to be turned on; when the control signal is at a second level, controls the third switching circuit to be turned on; the second switching circuit is used to, when turned on, connect a power supply voltage to the first nozzle to start the first nozzle; the third switching circuit is used to, when turned on, connect the power supply voltage to the second nozzle to start the second nozzle; wherein the first nozzle and the second nozzle burn different fuels.

[0004] In some embodiments, the first switching circuit includes:

[0005] A first transistor; the control terminal of the first transistor is used to receive the control signal; the first terminal of the first transistor is connected to a first voltage node; the second terminal of the first transistor is grounded through a first resistor; the voltage of the first voltage node is higher than ground;

[0006] The second transistor; the control terminal of the second transistor is connected to the second terminal of the first transistor; the first terminal of the second transistor is connected to the first voltage node; the second terminal of the second transistor is grounded;

[0007] A third transistor; the control terminal of the third transistor is connected to the first voltage node via a second resistor; the first terminal of the third transistor is connected to the second voltage node via a third resistor; the second terminal of the third transistor is grounded; the voltage at the connection between the first terminal of the third transistor and the third resistor is used to control the conduction or disconnection of the second switching circuit; the second voltage node is used to connect to the power supply voltage;

[0008] A fourth transistor; the control terminal of the fourth transistor is connected to the second terminal of the first transistor; the first terminal of the fourth transistor is connected to the second voltage node via a fourth resistor; the second terminal of the fourth transistor is grounded; the voltage at the connection between the first terminal of the fourth transistor and the fourth resistor is used to control the conduction or disconnection of the third switching circuit.

[0009] In some embodiments, the second switching circuit includes: a fifth transistor; the control terminal of the fifth transistor is connected to the first terminal of the third transistor; the first terminal of the fifth transistor is connected to the second voltage node; and the second terminal of the fifth transistor is connected to the power interface of the first nozzle.

[0010] The third switching circuit includes: a sixth transistor; the control terminal of the sixth transistor is connected to the first terminal of the fourth transistor; the first terminal of the sixth transistor is connected to the second voltage node; and the second terminal of the sixth transistor is connected to the power interface of the second nozzle.

[0011] In some embodiments, the control terminal of the second transistor is connected to the control terminal of the fourth transistor and then connected to the second terminal of the first transistor via a fifth resistor.

[0012] In some embodiments, the switching circuit further includes: a controller and at least one set of diagnostic circuits; wherein,

[0013] Each set of diagnostic circuits is used to diagnose the status of at least two nozzles; wherein each nozzle corresponds to a diagnostic resistor with a different resistance value; when a nozzle is in working condition, the corresponding diagnostic resistor is connected to the controller.

[0014] The controller is used to determine whether each nozzle is in working condition based on the input resistance value, and to determine whether the nozzle in working condition is abnormally working or normally working based on the determination conditions.

[0015] In some embodiments, each set of diagnostic circuits includes: at least two transistors; a control terminal of each of the at least two transistors is connected to a power interface of a nozzle; a first terminal of each transistor is connected to a diagnostic interface of the controller; a second terminal of each transistor is connected to ground via a diagnostic resistor; wherein the second terminals of each of the at least two transistors are connected in parallel to the diagnostic interface, and each of the at least two transistors corresponds to a diagnostic resistor with a different resistance value.

[0016] In some embodiments, the at least two transistors include: a seventh transistor, an eighth transistor, and a ninth transistor, wherein,

[0017] The control terminal of the seventh transistor is connected to the power interface of the first nozzle; the first terminal of the seventh transistor is connected to the diagnostic interface; the second terminal of the seventh transistor is connected to ground via the first diagnostic resistor.

[0018] The control terminal of the eighth transistor is connected to the power interface of the second nozzle; the first terminal of the eighth transistor is connected to the diagnostic interface; the second terminal of the eighth transistor is connected to ground via the second diagnostic resistor.

[0019] The control terminal of the ninth transistor is connected to the power interface of the third nozzle; the first terminal of the ninth transistor is connected to the diagnostic interface; the second terminal of the ninth transistor is connected to ground via the third diagnostic resistor; wherein the resistance values ​​of the first diagnostic resistor, the second diagnostic resistor, and the third diagnostic resistor are different.

[0020] In some embodiments, the diagnostic circuit further includes: at least two voltage divider circuits corresponding to each group of diagnostic circuits; each voltage divider circuit corresponds to one of the at least two transistors; the voltage divider circuit is used to provide voltage divider protection for the corresponding transistor.

[0021] In some embodiments, each voltage divider circuit includes: a first voltage divider resistor and a second voltage divider resistor; wherein the first voltage divider resistor and the second voltage divider resistor are connected in series between the power interface of the corresponding nozzle and ground; the control terminal of the transistor corresponding to the voltage divider circuit is connected to the connection line between the first voltage divider resistor and the second voltage divider resistor.

[0022] Secondly, embodiments of this application also provide a vehicle including the switching circuit described in any of the preceding claims.

[0023] This application provides a switching circuit for a dual-fuel injector and a vehicle. The dual-fuel injector switching circuit includes at least one set of logic control circuits; each set of logic control circuits controls the switching between two injectors using different fuels; each set of logic control circuits includes a first switching circuit, a second switching circuit, and a third switching circuit, wherein: the first switching circuit is used to receive a control signal, and when the control signal is at a first level, controls the second switching circuit to conduct; when the control signal is at a second level, controls the third switching circuit to conduct; the second switching circuit, when conducting, is used to connect a power supply voltage to the first injector to start the first injector; the third switching circuit, when conducting, is used to connect the power supply voltage to the second injector to start the second injector; wherein the first injector and the second injector burn different fuels. The switching circuit provided in this application includes three switching circuits, wherein the first switching circuit controls the conduction and deactivation of the second or third switching circuit according to the two levels of the control signal, thereby realizing the switching between the two injectors. Attached Figure Description

[0024] Figure 1 The diagram shown is a schematic representation of the switching circuit for the dual fuel nozzles provided in an embodiment of this application. Figure 1 .

[0025] Figure 2 The diagram shown is an exemplary schematic of the working principle of the logic control circuit provided in the embodiment of this application.

[0026] Figure 3 As shown Figure 2 The diagram shows an exemplary operating logic timing diagram of the logic control circuit.

[0027] Figure 4 The diagram shown is a schematic of the working state of the logic control circuit provided in the embodiment of this application when the control signal is high.

[0028] Figure 5 The diagram shown is a schematic of the working state of the logic control circuit provided in the embodiment of this application when the control signal is low.

[0029] Figure 6 The diagram shown is an exemplary structural schematic of the first switch circuit, the second switch circuit, and the third switch circuit provided in an embodiment of this application.

[0030] Figure 7 The diagram shown is a schematic representation of the switching circuit for the dual fuel nozzles provided in an embodiment of this application. Figure 2 .

[0031] Figure 8 The diagram shown is a schematic diagram of the diagnostic circuit for the diagnostic status of three nozzles provided in an embodiment of this application. Detailed Implementation

[0032] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0033] In the automotive industry, to address the difficulty of starting methanol engines in low-temperature environments, the engine is first started with gasoline before switching to methanol fuel. Therefore, two sets of fuel injectors are designed to inject both gasoline and methanol. However, current mature engine controllers only have a drive circuit for one set of fuel injectors, which cannot meet the control requirements of two sets of injectors.

[0034] To address the aforementioned technical problems, this application provides a switching circuit that uses three switching circuits. The first switching circuit controls the conduction and de-conduction of the second or third switching circuit based on two levels of a control signal, thereby enabling the switching of two nozzles.

[0035] Specifically, such as Figure 1 The diagram shown illustrates the structure of a dual-fuel nozzle switching circuit according to an embodiment of this application. Figure 1 In the switching circuit 100, there are at least one set of logic control circuits 101; each set of logic control circuits is used to control the switching of two nozzles using different fuels; each set of logic control circuits 101 includes: a first switching circuit 1011, a second switching circuit 1012 and a third switching circuit 1013, wherein;

[0036] The first switching circuit 1011 is used to receive a control signal, and when the control signal is at a first level, it controls the second switching circuit to turn on; when the control signal is at a second level, it controls the third switching circuit to turn on.

[0037] The second switching circuit 1012 is used to connect the power supply voltage to the first nozzle when it is turned on, so as to start the first nozzle to work;

[0038] The third switching circuit 1013 is used to connect the power supply voltage to the second nozzle when it is turned on, so as to start the second nozzle to work; wherein the first nozzle and the second nozzle burn different fuels.

[0039] It should be noted that, in practice, an engine can contain multiple sets of dual-fuel injectors, and each set of dual-fuel injectors contains two injectors that use different fuels. The switching circuit provided in this application embodiment includes at least one set of logic control circuits; each set of logic control circuits controls the switching of the two injectors using different fuels, that is, each set of logic control circuits can control the switching of one set of dual-fuel injectors.

[0040] The specific switching principle, such as Figure 2 As shown, three switching circuits are used to achieve two outputs with opposite logic states according to the control signal, so as to connect the working power supply to different nozzles. Among them, IN is the voltage of the working power supply; Ctrl is the control signal; INJ1 and INJ2 are the high-side power supplies (such as the positive voltage terminal of the power supply interface of the nozzle) of two nozzles with different fuels (such as the first nozzle and the second nozzle) in a group of fuel nozzles.

[0041] Furthermore, an achievable working principle can be as follows: Figures 3 to 5 As shown, specifically:

[0042] like Figure 3As shown, it illustrates a schematic diagram of a switchable level logic relationship. According to... Figure 2 As shown, in stage ①, Ctrl is at a high voltage (e.g., the first level), and INJ1 is enabled, as shown below. Figure 4 IN and INJ1 are connected, enabling INJ1 to operate. At this time, INJ2 is in an open-circuit state, i.e., not operating. In stage ②, Ctrl is at a low voltage (e.g., the second level), and INJ2 is enabled, as shown below. Figure 5 When IN and INJ2 are connected, INJ2 is in a working state. At this time, INJ1 is in an open circuit state, that is, in a non-working state.

[0043] In specific implementation, such as Figure 6 As shown, the first switching circuit 1011 may include:

[0044] The first transistor is QP1; the control terminal of the first transistor is used to receive the control signal; the first terminal of the first transistor is connected to the first voltage node U1; the second terminal of the first transistor is grounded through the first resistor R1; the voltage of the first voltage node U1 is higher than ground.

[0045] The second transistor is QN1A; the control terminal of the second transistor is connected to the second terminal of the first transistor; the first terminal of the second transistor is connected to the first voltage node; the second terminal of the second transistor is grounded.

[0046] The third transistor is QN2A; the control terminal of the third transistor is connected to the first voltage node via the second resistor R3; the first terminal of the third transistor is connected to the second voltage node IN via the third resistor R4; the second terminal of the third transistor is grounded; the voltage at the connection between the first terminal of the third transistor and the third resistor is used to control the conduction or disconnection of the second switching circuit; the second voltage node is used to connect to the power supply voltage;

[0047] The fourth transistor QN3A; the control terminal of the fourth transistor is connected to the second terminal of the first transistor; the first terminal of the fourth transistor is connected to the second voltage node via the fourth resistor R6; the second terminal of the fourth transistor is grounded; the voltage at the connection between the first terminal of the fourth transistor and the fourth resistor is used to control the conduction or disconnection of the third switching circuit.

[0048] In some embodiments, such as Figure 6 As shown, the second switching circuit 1012 includes: a fifth transistor QP2; the control terminal of the fifth transistor is connected to the first terminal of the third transistor; the first terminal of the fifth transistor is connected to the second voltage node; and the second terminal of the fifth transistor is connected to the power interface (i.e., INJ1) of the first nozzle.

[0049] The third switching circuit 1013 includes: a sixth transistor QP3; the control terminal of the sixth transistor is connected to the first terminal of the fourth transistor; the first terminal of the sixth transistor is connected to the second voltage node; and the second terminal of the sixth transistor is connected to the power interface (i.e., INJ2) of the second nozzle.

[0050] It should be noted that, Figure 6 Exemplary structures of the first, second, and third switching circuits, along with schematic diagrams illustrating the connections between their components, are shown. According to... Figure 6 As shown, the switching circuit provided in this application embodiment realizes the switching of dual fuel nozzles according to the following principle: the first transistor is controlled by a control signal to turn on or off. Furthermore, the combination of the first, second, and third transistors controls the conduction or disconnection of the second switching circuit; the combination of the first and fourth transistors controls the conduction or disconnection of the third switching circuit. Here, the control terminals of QP1, QP2, and QP3 are also the gates of the transistors, the first terminals of QP1, QP2, and QP3 are also the drains of the transistors, and the second terminals of QP1, QP2, and QP3 are also the sources of the transistors. Similarly, the control terminals of QN1A, QN2A, and QN3A are also the gates of the transistors, the first terminals of QN1A, QN2A, and QN3A are also the drains of the transistors, and the second terminals of QN1A, QN2A, and QN3A are also the sources of the transistors.

[0051] In some embodiments, when the first transistor, the fifth transistor, and the sixth transistor are PMOS transistors; and the second transistor, the third transistor, and the fourth transistor are NMOS transistors, such as Figure 6 As shown, the switching principle can be as follows: When the first transistor is in a high-level state, it is in an off state. At this time, the control terminals of the second and fourth transistors are pulled low and are in an off state. When the control terminal of the third transistor is turned on by the voltage of the first voltage node, it pulls the control terminal of the fifth transistor low to ground, making the fifth transistor in a closed state. That is, it controls the second switching circuit to conduct, so that the power supply voltage is connected to the first nozzle. When the first transistor is in a low-level state and is closed, the second and fourth transistors are turned on by the voltage across the first resistor, and the third transistor is turned on by the first voltage node. At this time, the fifth transistor is turned off by the voltage across the third resistor, that is, the second switching circuit is open. The control terminal of the sixth transistor is pulled low to ground by the conduction of the fourth transistor, that is, the sixth transistor is turned on, so that the third switching circuit is turned on, so that the power supply voltage is connected to the second nozzle. Thus, according to the different voltage states of the control signal, the first nozzle or the second nozzle can be turned on, and the switching of different nozzles can be realized.

[0052] In some embodiments, such as Figure 6As shown, the control terminal of the second transistor is connected to the control terminal of the fourth transistor and then connected to the second terminal of the first transistor via the fifth resistor R2.

[0053] It should be noted that the function of this fifth resistor is to limit current. In practice, as... Figure 6 As shown, the control terminal of the fifth transistor is connected to the first terminal of the third transistor via the sixth resistor R5; the control terminal of the sixth transistor is connected to the first terminal of the fourth transistor via the seventh resistor R7. Both the sixth and seventh resistors are used for current limiting.

[0054] In some embodiments, if a device includes multiple sets of the above-described dual-fuel nozzles, for example, a car includes six sets of dual-fuel nozzles, then the device requires six of the above-described nozzles. Figure 6 The logic control circuit described.

[0055] In some embodiments, such as Figure 7 As shown, the switching circuit further includes: a controller 102 and at least one set of diagnostic circuits 103; wherein,

[0056] Each set of diagnostic circuits 103 is used to diagnose the status of at least two nozzles; wherein each nozzle corresponds to a diagnostic resistor with a different resistance value; when a nozzle is in working state, the corresponding diagnostic resistor is connected to the controller.

[0057] The controller 102 is used to determine whether each nozzle is in working condition based on the input resistance value, and to determine whether the nozzle in working condition is abnormally working or normally working based on the determination conditions.

[0058] It should be noted that the state referred to can be either in operation or not in operation. In operation, the nozzle is open; in operation, the nozzle is closed. The switching circuit may also include at least one set of diagnostic circuits 103, in which one nozzle corresponds to one diagnostic resistor, and each diagnostic resistor has a different resistance value. When a nozzle is in operation, the corresponding diagnostic resistor is connected to the diagnostic network included in the controller. The controller determines whether each nozzle is in operation based on the connected resistance value, and determines whether the nozzle in operation is abnormally operating or normally operating based on a judgment condition. Abnormal operation can mean that the nozzle in operation should not be operating; normal operation can mean that the nozzle in operation should be operating. In other words, the controller determines which nozzles are in operation based on the connected resistance value, and then determines whether the nozzles in operation are abnormal or normal based on the judgment condition. The judgment condition can be obtained from the operating status of the device in which the switching circuit is located or from a set operating program. That is, the controller knows which nozzles should be operating and which should not be operating. Therefore, the controller determines which nozzles are in operation based on the input resistance value, and then, based on the determination conditions, it can determine which nozzle is abnormal and which nozzle is normal.

[0059] In some embodiments, the controller stores the resistance values ​​corresponding to different nozzles when they are connected. Therefore, the controller can determine which nozzles are in operation based on the actual connected resistance values.

[0060] In some embodiments, each set of diagnostic circuits may include: at least two transistors; the control terminal of each of the at least two transistors is connected to the power interface of a nozzle; the first terminal of each transistor is connected to the diagnostic interface of the controller; the second terminal of each transistor is connected to ground via a diagnostic resistor; wherein the second terminal of each of the at least two transistors is connected in parallel to the diagnostic interface, and each of the at least two transistors corresponds to a diagnostic resistor with a different resistance value.

[0061] It should be noted that each nozzle corresponds to a transistor. When a nozzle is in operation, its power interface is connected to the power supply voltage, causing the corresponding transistor to conduct, which in turn connects the diagnostic resistor corresponding to the nozzle to the controller's diagnostic interface. Furthermore, the connection method for the diagnostic resistors corresponding to each nozzle in a diagnostic circuit to the controller can be either series or parallel, depending on the specific design requirements.

[0062] In one possible embodiment, assuming the diagnostic resistors are connected in parallel within the controller, the resistance values ​​of different nozzles connected in parallel can be calculated and stored in the controller's memory. Then, based on the actual connected resistance value, it is compared with multiple resistance values ​​stored in memory to determine which diagnostic resistors are connected in parallel, and thus which nozzles are in operation.

[0063] The at least two transistors mentioned can be NMOS transistors.

[0064] In some embodiments, such as Figure 8 As shown, the at least two transistors include: a seventh transistor QND1, an eighth transistor QND2, and a ninth transistor QND3, wherein,

[0065] The control terminal of the seventh transistor QND1 is connected to the power interface of the first nozzle; the first terminal of the seventh transistor is connected to the diagnostic interface; the second terminal of the seventh transistor is connected to ground via the first diagnostic resistor.

[0066] The control terminal of the eighth transistor QND2 is connected to the power interface of the second nozzle; the first terminal of the eighth transistor is connected to the diagnostic interface; the second terminal of the eighth transistor is connected to ground via the second diagnostic resistor.

[0067] The control terminal of the ninth transistor QND3 is connected to the power interface of the third nozzle; the first terminal of the ninth transistor is connected to the diagnostic interface; the second terminal of the ninth transistor is connected to ground via the third diagnostic resistor; wherein the resistance values ​​of the first diagnostic resistor, the second diagnostic resistor, and the third diagnostic resistor are different.

[0068] It should be noted that, Figure 8 This is an example of a diagnostic circuit capable of diagnosing three nozzles. Figure 8In this example, assume that diagnostic resistor RD3 corresponds to the first nozzle; diagnostic resistor RD6 corresponds to the second nozzle; and diagnostic resistor RD9 corresponds to the third nozzle, and that RD3, RD6, and RD9 are connected to the controller in parallel. Then, if only one nozzle is connected, the resistance value connected to the controller can be one of RD3, RD6, or RD9; if two nozzles are connected, the resistance value connected to the controller can be any two of RD3, RD6, and RD9 connected in parallel; and if three nozzles are connected, the resistance value connected to the controller can be the parallel resistance of RD3, RD6, and RD9. These calculated resistance values ​​can be stored in the controller's memory. During use, after the controller obtains the connected resistance values, it compares the calculated resistance values ​​with the resistance values ​​stored in memory to determine which nozzles are in operation. Here, the control terminals of QND1, QND2, and QND3 are also the gate terminals of the transistors, the first terminals of QND1, QND2, and QND3 are also the drain terminals of the transistors, and the second terminals of QND1, QND2, and QND3 are also the source terminals of the transistors.

[0069] In some embodiments, the diagnostic circuit further includes: at least two voltage divider circuits corresponding to each group of diagnostic circuits; each voltage divider circuit corresponds to one of the at least two transistors; the voltage divider circuit is used to provide voltage divider protection for the corresponding transistor.

[0070] In some embodiments, each voltage divider circuit may include: a first voltage divider resistor and a second voltage divider resistor; wherein the first voltage divider resistor and the second voltage divider resistor are connected in series between the power interface of the corresponding nozzle and ground; the control terminal of the transistor corresponding to the voltage divider circuit is connected to the connection line between the first voltage divider resistor and the second voltage divider resistor.

[0071] For example, such as Figure 8 As shown, the voltage divider circuit corresponding to the seventh transistor QND1 includes first voltage divider resistors RD1 and second voltage divider resistors RD2 and RD4 and RD5, respectively; the voltage divider circuit corresponding to the eighth transistor QND2 includes first voltage divider resistors RD7 and RD8, respectively.

[0072] In some embodiments, if a device includes multiple sets of the aforementioned dual-fuel nozzles, for example, a car includes 6 sets of dual-fuel nozzles, then the device has a total of 12 nozzles. Regarding the aforementioned 4... Figure 8 The diagnostic circuit shown.

[0073] This application also provides a vehicle including the switching circuit described in any of the preceding claims.

[0074] It should be noted that the vehicle provided in the embodiments of this application includes the switching circuit of any of the above-mentioned items. Therefore, the description of any component in the switching circuit has been clearly described above and will not be repeated here.

[0075] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Any modifications or equivalent substitutions made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A switching circuit for a dual-fuel nozzle, characterized in that, include: At least one set of logic control circuits; Each set of logic control circuits is used to control the switching between two nozzles using different fuels; Each set of logic control circuits includes: a first switching circuit, a second switching circuit, and a third switching circuit, wherein; The first switching circuit is used to receive a control signal, and when the control signal is at a first level, it controls the second switching circuit to turn on; when the control signal is at a second level, it controls the third switching circuit to turn on. The second switching circuit is used to connect the power supply voltage to the first nozzle when it is turned on, so as to start the first nozzle to work; The third switching circuit is used to connect the power supply voltage to the second nozzle when it is turned on, so as to start the second nozzle from operating; wherein the first nozzle and the second nozzle burn different fuels; wherein the first switching circuit includes: A first transistor; the control terminal of the first transistor is used to receive the control signal; the first terminal of the first transistor is connected to a first voltage node; the second terminal of the first transistor is grounded through a first resistor; the voltage of the first voltage node is higher than ground; The second transistor; the control terminal of the second transistor is connected to the second terminal of the first transistor; the first terminal of the second transistor is connected to the first voltage node; the second terminal of the second transistor is grounded; A third transistor; the control terminal of the third transistor is connected to the first voltage node via a second resistor; the first terminal of the third transistor is connected to the second voltage node via a third resistor; the second terminal of the third transistor is grounded; the voltage at the connection between the first terminal of the third transistor and the third resistor is used to control the conduction or disconnection of the second switching circuit; the second voltage node is used to connect to the power supply voltage; A fourth transistor; the control terminal of the fourth transistor is connected to the second terminal of the first transistor; the first terminal of the fourth transistor is connected to the second voltage node via a fourth resistor; the second terminal of the fourth transistor is grounded; the voltage at the connection between the first terminal of the fourth transistor and the fourth resistor is used to control the conduction or disconnection of the third switching circuit.

2. The circuit according to claim 1, characterized in that, The second switching circuit includes: a fifth transistor; the control terminal of the fifth transistor is connected to the first terminal of the third transistor; the first terminal of the fifth transistor is connected to the second voltage node; and the second terminal of the fifth transistor is connected to the power interface of the first nozzle. The third switching circuit includes: a sixth transistor; the control terminal of the sixth transistor is connected to the first terminal of the fourth transistor; the first terminal of the sixth transistor is connected to the second voltage node; and the second terminal of the sixth transistor is connected to the power interface of the second nozzle.

3. The circuit according to claim 1, characterized in that, The control terminal of the second transistor is connected to the control terminal of the fourth transistor and then connected to the second terminal of the first transistor via a fifth resistor.

4. The circuit according to claim 1, characterized in that, The switching circuit further includes: a controller and at least one set of diagnostic circuits; wherein... Each set of diagnostic circuits is used to diagnose the status of at least two nozzles; wherein each nozzle corresponds to a diagnostic resistor with a different resistance value; when a nozzle is in working condition, the corresponding diagnostic resistor is connected to the controller. The controller is used to determine whether each nozzle is in working condition based on the input resistance value, and to determine whether the nozzle in working condition is abnormally working or normally working based on the determination conditions.

5. The circuit according to claim 4, characterized in that, Each diagnostic circuit includes: at least two transistors; the control terminal of each of the at least two transistors is connected to the power interface of a nozzle; the first terminal of each transistor is connected to the diagnostic interface of the controller; the second terminal of each transistor is connected to ground via a diagnostic resistor; wherein the second terminal of each of the at least two transistors is connected in parallel to the diagnostic interface, and each of the at least two transistors corresponds to a diagnostic resistor with a different resistance value.

6. The circuit according to claim 5, characterized in that, The at least two transistors include: a seventh transistor, an eighth transistor, and a ninth transistor, wherein, The control terminal of the seventh transistor is connected to the power interface of the first nozzle; the first terminal of the seventh transistor is connected to the diagnostic interface; the second terminal of the seventh transistor is connected to ground via the first diagnostic resistor. The control terminal of the eighth transistor is connected to the power interface of the second nozzle; the first terminal of the eighth transistor is connected to the diagnostic interface; the second terminal of the eighth transistor is connected to ground via the second diagnostic resistor. The control terminal of the ninth transistor is connected to the power interface of the third nozzle; the first terminal of the ninth transistor is connected to the diagnostic interface; the second terminal of the ninth transistor is connected to ground via the third diagnostic resistor; wherein the resistance values ​​of the first diagnostic resistor, the second diagnostic resistor, and the third diagnostic resistor are different.

7. The circuit according to claim 5, characterized in that, The diagnostic circuit further includes: at least two voltage divider circuits corresponding to each group of diagnostic circuits; each voltage divider circuit corresponds to one of the at least two transistors; the voltage divider circuit is used to provide voltage divider protection for the corresponding transistor.

8. The circuit according to claim 7, characterized in that, Each voltage divider circuit includes: a first voltage divider resistor and a second voltage divider resistor; wherein the first voltage divider resistor and the second voltage divider resistor are connected in series between the power interface of the corresponding nozzle and ground; the control terminal of the transistor corresponding to the voltage divider circuit is connected to the connection line between the first voltage divider resistor and the second voltage divider resistor.

9. A vehicle, characterized in that, Includes the switching circuit described in any one of claims 1 to 8 above.

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