Switching circuit of dual-fuel nozzle and vehicle

Abstract

The embodiment of the invention provides a switching circuit of a dual-fuel nozzle and a vehicle. The switching circuit comprises at least one group of logic control circuits; each group of logic control circuit comprises a first switch circuit, a second switch circuit and a third switch circuit; the first switching circuit is used for accessing a control signal and controlling the second switching circuit to be switched on when the control signal is at a first level; when the control signal is in a second level, the third switching circuit is controlled to be switched on; the second switching circuit is used for connecting the power supply voltage to the first nozzle when the second switching circuit is switched on; and the third switching circuit is used for connecting the power supply voltage to the second nozzle when the third switching circuit is switched on. A circuit for controlling the switching of two nozzles with different fuels is arranged, the circuit comprises three switching circuits, and the first switching circuit controls the on and off of the second switching circuit or the third switching circuit according to two levels of a control signal, so that the switching of the two nozzles is realized.

Description

Technical Field

[0001] The embodiments of the present application relate to the field of electronic appliances, and in particular to a switching circuit for a dual-fuel nozzle and a vehicle. Background Art

[0002] In the automotive field, currently mature engine controllers only have one set of fuel nozzle drive circuits and cannot meet the control requirements of two sets of nozzles. Summary of the invention

[0003] In a first aspect, an embodiment of the present application provides a switching circuit for a dual-fuel nozzle, comprising: at least one group of logic control circuits; each group of logic control circuits is used to control the switching of two nozzles using different fuels; each group of logic control circuits includes: a first switch circuit, a second switch circuit and a third switch circuit, wherein; the first switch circuit is used to access a control signal, and when the control signal is at a first level, control the second switch circuit to be turned on; when the control signal is at a second level, control the third switch circuit to be turned on; the second switch 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 switch 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 to work; wherein the first nozzle and the second nozzle burn different fuels.

[0004] In some embodiments, the first switch circuit comprises:

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

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

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

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

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

[0010] The third switch circuit includes: a sixth transistor; a control end of the sixth transistor is connected to the first end of the fifth transistor; a first end of the sixth transistor is connected to the second voltage node; and a second end 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 comprises: a controller and at least one set of diagnostic circuits; wherein,

[0013] Each group 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 certain nozzle is in a working state, the corresponding diagnostic resistor is connected to the controller;

[0014] The controller is used to determine whether each nozzle is in a working state according to the connected resistance value, and to determine whether the nozzle in the working state is working abnormally or normally according to the determination condition.

[0015] In some embodiments, each group of diagnostic circuits includes: at least two transistors; the control end of each of the at least two transistors is connected to the power interface of a nozzle; the first end of each of the transistors is connected to the diagnostic interface of the controller; the second end of each of the transistors is used to be connected to the ground via a diagnostic resistor; wherein the second end 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.

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

[0017] The control end of the seventh transistor is connected to the second end of the fourth transistor; the first end of the seventh transistor is connected to the diagnostic interface; the second end of the seventh transistor is connected to the ground via the first diagnostic resistor;

[0018] The control end of the eighth transistor is connected to the second end of the sixth transistor; the first end of the eighth transistor is connected to the diagnostic interface; the second end of the eighth transistor is connected to the ground via the second diagnostic resistor;

[0019] The control end of the ninth transistor is connected to the power supply interface of the third nozzle; the first end of the ninth transistor is connected to the diagnostic interface; the second end of the ninth transistor is connected to the 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; and the voltage divider circuit is used to perform voltage divider protection on the corresponding transistor.

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

[0022] In a second aspect, an embodiment of the present application further provides a vehicle, comprising a switching circuit as described in any one of the above items.

[0023] The embodiment of the present application provides a switching circuit and a vehicle for a dual-fuel nozzle. The switching circuit for the dual-fuel nozzle includes: at least one group of logic control circuits; each group of logic control circuits controls the switching of two nozzles using different fuels; each group of logic control circuits includes: a first switch circuit, a second switch circuit and a third switch circuit, wherein: the first switch circuit is used to access a control signal, and when the control signal is at a first level, control the second switch circuit to be turned on; when the control signal is at a second level, control the third switch circuit to be turned on; the second switch circuit is used to connect the power supply voltage to the first nozzle when it is turned on to start the first nozzle to work; the third switch circuit is used to connect the power supply voltage to the second nozzle when it is turned on to start the second nozzle to work; wherein the first nozzle and the second nozzle burn different fuels. The switching circuit provided in the embodiment of the present application includes three switch circuits, wherein the first switch circuit controls the conduction and disconnection of the second switch circuit or the third switch circuit according to the two levels of the control signal, thereby realizing the switching of the two nozzles. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 The figure shows the structure of the switching circuit of the dual fuel nozzle provided in the embodiment of the present application. Figure 1 ;

[0025] Figure 2 The figure is an exemplary schematic diagram of the working principle of the logic control circuit provided in the embodiment of the present application;

[0026] Figure 3 Shown Figure 2 An exemplary working logic timing diagram of the logic control circuit shown;

[0027] Figure 4 The figure is a schematic diagram of the working state of the logic control circuit provided in the embodiment of the present application when the control signal is at a high level;

[0028] Figure 5 The figure is a schematic diagram of the working state of the logic control circuit provided in the embodiment of the present application when the control signal is at a low level;

[0029] Figure 6 The figure shows an exemplary structural diagram of a first switch circuit, a second switch circuit and a third switch circuit provided in an embodiment of the present application;

[0030] Figure 7 The figure shows the structure of the switching circuit of the dual fuel nozzle provided in the embodiment of the present application. Figure 2 ;

[0031] Figure 8 Shown is a schematic diagram of the structure of a diagnostic circuit for three nozzle diagnostic states provided in an embodiment of the present application. DETAILED DESCRIPTION

[0032] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0033] In the automotive field, in order to solve the problem of methanol engine starting difficulty at low temperature, the engine is started with gasoline at low temperature and then switched to methanol fuel. Therefore, two sets of fuel nozzles are designed to realize gasoline and methanol injection. However, the current mature engine controller only has one set of fuel nozzle drive circuits, which cannot meet the control requirements of two sets of nozzles.

[0034] In order to solve the above technical problems, an embodiment of the present application provides a switching circuit, which realizes the switching of two nozzles by setting three switching circuits, wherein the first switching circuit controls the conduction and disconnection of the second switching circuit or the third switching circuit according to the two levels of the control signal.

[0035] Specifically, Figure 1 As shown, it shows a schematic diagram of the structure of a switching circuit of a dual fuel nozzle provided in an embodiment of the present application. Figure 1 In the switching circuit 100, at least one group of logic control circuits 101 is included; each group of logic control circuits is used to control the switching of two nozzles using different fuels; each group of logic control circuits 101 includes a first switch circuit 1011, a second switch circuit 1012 and a third switch circuit 1013, wherein;

[0036] The first switch circuit 1011 is used to receive a control signal, and when the control signal is at a first level, control the second switch circuit to be turned on; when the control signal is at a second level, control the third switch circuit to be turned on;

[0037] The second switch 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 switch circuit 1013 is used for connecting 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 may include multiple groups of dual-fuel nozzles, and each group of dual-fuel nozzles includes two nozzles using different fuels. The switching circuit provided in the embodiment of the present application includes at least one group of logic control circuits; each group of logic control circuits controls the switching of two nozzles using different fuels, that is, each group of logic control circuits can control the switching of one group of dual-fuel nozzles.

[0040] Specific switching principle, such as Figure 2 As shown, three switch circuits are used to realize 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 respectively the high-side power supplies (such as the voltage positive end of the power supply interface of the nozzle) of two nozzles of different fuels (such as the first nozzle and the second nozzle) in a group of fuel nozzles.

[0041] And, a feasible working principle can be as follows Figures 3 to 5 As shown, specifically:

[0042] like Figure 3 As shown, it shows a schematic diagram of a level logic relationship that can achieve switching. Figure 2 As shown, in stage ①, Ctrl is a high voltage (such as the first level), and the logic circuit INJ1 is enabled, such as Figure 4 , IN and INJ1 are turned on, so that INJ1 is in working state. At this time, INJ2 is in open circuit state, that is, not in working state. In stage ②, Ctrl is a low voltage (such as the second level), and the logic circuit INJ2 is enabled, such as Figure 5 , IN and INJ2 are connected, so that INJ2 is in working state. At this time, INJ1 is in the open circuit state, that is, the non-working state.

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

[0044] A first transistor QP1; the control terminal of the first transistor is used to access 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 via the first resistor R1; the voltage of the first voltage node U1 is higher than the ground;

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

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

[0047] A fourth transistor QN3A; the control end of the fourth transistor is connected to the second end of the first transistor; the first end of the fourth transistor is connected to the second voltage node via a fourth resistor R6; the second end of the fifth transistor is grounded; and the voltage at the connection point between the first end of the fourth transistor and the fourth resistor is used to control the conduction or disconnection of the third switch circuit.

[0048] In some embodiments, Figure 6 As shown, the second switch circuit 1012 includes: a fifth transistor QP2; the control end of the fifth transistor is connected to the first end of the third transistor; the first end of the fifth transistor is connected to the second voltage node; the second end of the fifth transistor is connected to the power interface of the first nozzle (ie, INJ1);

[0049] The third switch circuit 1013 includes: a sixth transistor QP3; the control end of the sixth transistor is connected to the first end of the fifth transistor; the first end of the sixth transistor is connected to the second voltage node; the second end of the sixth transistor is connected to the power interface of the second nozzle (ie, INJ2).

[0050] It should be noted that Figure 6 The exemplary structures of the first switch circuit, the second switch circuit and the third switch circuit and the connection diagram between the various components are shown. Figure 6 As shown, the switching circuit provided in the embodiment of the present application realizes the switching of the dual fuel nozzle according to the following principle: the first transistor is controlled by the control signal to turn on or off. And the first transistor, the second transistor and the third transistor are combined to control the conduction or disconnection of the second switch circuit; the first transistor and the fourth transistor are combined to control the conduction or disconnection of the third switch circuit. Here, the control end of QP1, QP2, and QP3 is also the gate of the transistor, the first end of QP1, QP2, and QP3 is also the drain end of the transistor, and the second end of QP1, QP2, and QP3 is also the source end of the transistor. The control end of QN1A, QN2A, and QN3A is also the gate of the transistor, the first end of QN1A, QN2A, and QN3A is also the drain end of the transistor, and the second end of QN1A, QN2A, and QN3A is also the source end of the transistor.

[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, Figure 6 As shown, the switching principle can be as follows: the first transistor is in an off state under the action of a high level, and at this time, the control terminals of the second transistor and the fourth transistor are pulled down and are in an off state; after the control terminal of the third transistor is turned on due to the voltage of the first voltage node, the control terminal of the fifth transistor is pulled down to ground, so that the fifth transistor is in a closed state, that is, the second switch circuit is controlled to be turned on, so that the power supply voltage is connected to the first nozzle; when the first transistor is in a closed state under the action of a low level, the second transistor and the fourth transistor are turned on due to the voltage across the first resistor, and the third transistor is turned on due to the first voltage node. At this time, the fifth transistor is turned off due to the voltage across the third resistor, that is, the second switch circuit is turned off; and the control terminal of the sixth transistor is pulled down to ground due to the conduction of the fourth transistor, that is, the sixth transistor is turned on, so that the third switch circuit is turned on, that is, the power supply voltage is connected to the second nozzle, so that the first nozzle or the second nozzle is put into operation according to different voltage states of the control signal, and switching of different nozzles can be realized.

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

[0053] It should be noted that the fifth resistor is used for current limiting. Figure 6 As shown, the control end of the fifth transistor is used to connect to the first end of the third transistor via the sixth resistor R5; the control end of the sixth transistor is used to connect to the first end of the fifth transistor via the seventh resistor R7. The sixth resistor and the seventh resistor are also used for current limiting.

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

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

[0056] Each group 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 a working state, the corresponding diagnostic resistor is connected to the controller;

[0057] The controller 102 is used to determine whether each nozzle is in a working state according to the connected resistance value, and determine whether the nozzle in the working state is working abnormally or normally according to the judgment condition.

[0058] It should be noted that the state mentioned may refer to being in operation or not in operation. Among them, being in operation means that the nozzle is in an open state; being not in operation means that the nozzle is in a closed state. Here, the switching circuit may also include at least one group of diagnostic circuits 103, in each group of diagnostic circuits 103, one nozzle corresponds to a diagnostic resistor, and the resistance value of each diagnostic resistor has a different resistance value. Moreover, when a nozzle is in operation, the corresponding diagnostic resistor is connected to the diagnostic network contained in the controller. The controller determines whether each nozzle is in operation according to the connected resistance value, and determines whether the nozzle in operation is abnormal or normal according to the judgment condition. Among them, the abnormal operation may mean that the nozzle in operation should not work; the normal operation may mean that the nozzle in operation should work. That is to say, the controller determines which nozzles are in operation according to the size of the connected resistance value, and then determines whether the nozzle in operation is abnormal or normal according to the judgment condition. The judgment condition may be obtained from the operation state of the device where the switching circuit is located or the set operation program. That is to say, the controller knows which nozzle should work and which nozzle should not work. Therefore, the controller determines which nozzles are in working condition according to the connected resistance value, and then according to the determination conditions, it can be known which nozzle is abnormal and which nozzle is normal.

[0059] In some embodiments, the controller stores the resistance values ​​corresponding to different nozzles connected, so the controller can determine which nozzles are in working state according to the actual connected resistance values.

[0060] In some embodiments, each group of diagnostic circuits may include: at least two transistors; the control end of each of the at least two transistors is connected to the power interface of a nozzle; the first end of each of the transistors is connected to the diagnostic interface of the controller; the second end of each of the transistors is used to be connected to the ground via a diagnostic resistor; wherein the second end 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 the nozzle is in operation, its power supply interface is connected to the power supply voltage, so that the corresponding transistor is turned on, and then the diagnostic resistor corresponding to the nozzle is connected to the diagnostic interface of the controller. In addition, the connection method of the diagnostic resistors corresponding to each nozzle in a diagnostic circuit to the controller can be in series or in parallel, which can be designed according to actual conditions.

[0062] In one practicable embodiment, it is assumed that the above-mentioned diagnostic resistors are connected in parallel in the controller. Based on this, the resistance values ​​of different nozzles connected in parallel can be calculated and stored in the memory of the controller. Then, according to the actual connected resistance value, it is compared with the multiple resistance values ​​stored in the memory to obtain which diagnostic resistors are connected in parallel, and then it can be obtained which nozzles are in working state.

[0063] The at least two transistors may be NMOS transistors.

[0064] In some embodiments, 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 end of the seventh transistor QND1 is connected to the second end of the fourth transistor; the first end of the seventh transistor is connected to the diagnostic interface; the second end of the seventh transistor is connected to the ground via the first diagnostic resistor;

[0066] The control end of the eighth transistor QND2 is connected to the second end of the sixth transistor; the first end of the eighth transistor is connected to the diagnostic interface; the second end of the eighth transistor is connected to the ground via the second diagnostic resistor;

[0067] The control end of the ninth transistor QND3 is connected to the power supply interface of the third nozzle; the first end of the ninth transistor is connected to the diagnostic interface; the second end of the ninth transistor is connected to the 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 that can diagnose three nozzles. Figure 8In the figure, it is assumed that the diagnostic resistor RD3 corresponds to the first nozzle; the diagnostic resistor RD6 corresponds to the second nozzle; the diagnostic resistor RD9 corresponds to the third nozzle, and the connection mode of RD3, RD6 and RD9 after being connected to the controller is in parallel. Then, if only one nozzle is connected, the resistance value connected to the controller can be one of RD3, RD6 and RD9; when two nozzles are connected, the resistance value connected to the controller can be the resistance value of any two of RD3, RD6 and RD9 connected in parallel; when three nozzles are connected, the resistance value connected to the controller can be the parallel resistance value of the three resistors RD3, RD6 and RD9. These calculated resistance values ​​can be stored in the memory of the controller. When in use, after the controller obtains the connected resistance value, it compares the calculated resistance value with the resistance value stored in the memory to determine which nozzles are in working state. Here, the control end of QND1, QND2, QND3 is also the gate end of the transistor, the first end of QND1, QND2, QND3 is also the drain end of the transistor, and the second end of QND1, QND2, QND3 is also the source end of the transistor.

[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; and the voltage divider circuit is used to perform voltage divider protection on the corresponding transistor.

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

[0071] For example, Figure 8 As shown, the voltage divider circuit corresponding to the seventh transistor QND1 includes first voltage divider resistors RD1 and RD2; the voltage divider circuit corresponding to the eighth transistor QND2 includes first voltage divider resistors RD4 and RD5; and the voltage divider circuit corresponding to the ninth transistor QND3 includes first voltage divider resistors RD7 and RD8.

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

[0073] An embodiment of the present application also provides a vehicle, comprising a switching circuit as described in any one of the above items.

[0074] It should be noted that the vehicle provided in the embodiment of the present application includes any of the switching circuits described above. Therefore, the description of any element in the switching circuit has been clearly described above and will not be repeated here.

[0075] The above description is only a preferred embodiment of the present application and is not intended to limit the present application. Any modifications, equivalent substitutions, etc. made within the spirit and principles of the present application shall be included in the protection scope of the present 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 of two nozzles using different fuels; Each set of logic control circuits includes: a first switch circuit, a second switch circuit and a third switch circuit, wherein; The first switch circuit is used to receive a control signal, and when the control signal is at a first level, control the second switch circuit to be turned on; when the control signal is at a second level, control the third switch circuit to be turned on; The second switch circuit is used to connect the power supply voltage to the first nozzle when it is turned on, so as to start the operation of the first nozzle; The third switch 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 to work; wherein, the first nozzle and the second nozzle burn different fuels.

2. The circuit according to claim 1, characterized in that The first switch circuit comprises: a first transistor; a control terminal of the first transistor is used to access the control signal; a first terminal of the first transistor is connected to a first voltage node; a second terminal of the first transistor is grounded via a first resistor; a voltage of the first voltage node is higher than ground; a second transistor; a control terminal of the second transistor is connected to the second terminal of the first transistor; a first terminal of the second transistor is connected to the first voltage node; a second terminal of the second transistor is grounded; a third transistor; the control end of the third transistor is connected to the first voltage node via a second resistor; the first end of the third transistor is connected to the second voltage node via a third resistor; the second end of the third transistor is grounded; the voltage at the connection point between the first end of the third transistor and the third resistor is used to control the conduction or disconnection of the second switch circuit; the second voltage node is used to connect to the power supply voltage; a fourth transistor; the control end of the fourth transistor is connected to the second end of the first transistor; the first end of the fourth transistor is connected to the second voltage node via a fourth resistor; the second end of the fifth transistor is grounded; and the voltage at the connection point between the first end of the fourth transistor and the fourth resistor is used to control the conduction or disconnection of the third switch circuit.

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

4. The circuit according to claim 2, characterized in that The control end of the second transistor is connected to the control end of the fourth transistor and then connected to the second end of the first transistor via a fifth resistor.

5. 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 group 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 certain nozzle is in a working state, the corresponding diagnostic resistor is connected to the controller; The controller is used to determine whether each nozzle is in a working state according to the connected resistance value, and to determine whether the nozzle in the working state is working abnormally or normally according to the determination condition.

6. The circuit according to claim 5, characterized in that Each group of diagnostic circuits includes: at least two transistors; the control end of each of the at least two transistors is connected to the power interface of a nozzle; the first end of each of the transistors is connected to the diagnostic interface of the controller; the second end of each of the transistors is used to be connected to the ground via a diagnostic resistor; wherein the second end 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.

7. The circuit according to claim 6, characterized in that The at least two transistors include: a seventh transistor, an eighth transistor and a ninth transistor, wherein: The control end of the seventh transistor is connected to the second end of the fourth transistor; the first end of the seventh transistor is connected to the diagnostic interface; the second end of the seventh transistor is connected to the ground via the first diagnostic resistor; The control end of the eighth transistor is connected to the second end of the sixth transistor; the first end of the eighth transistor is connected to the diagnostic interface; the second end of the eighth transistor is connected to the ground via the second diagnostic resistor; The control end of the ninth transistor is connected to the power supply interface of the third nozzle; the first end of the ninth transistor is connected to the diagnostic interface; the second end of the ninth transistor is connected to the 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.

8. The circuit according to claim 6, characterized in that The diagnostic circuit further includes: at least two voltage-dividing circuits corresponding to each group of diagnostic circuits; each voltage-dividing circuit corresponds to one of the at least two transistors; and the voltage-dividing circuit is used to perform voltage-dividing protection on the corresponding transistor.

9. The circuit according to claim 8, characterized in that Each of the voltage-dividing circuits includes: a first voltage-dividing resistor and a second voltage-dividing resistor; wherein the first voltage-dividing resistor and the second voltage-dividing resistor are connected in series between the power interface of the corresponding nozzle and the ground; and the control end of the transistor corresponding to the voltage-dividing circuit is connected to the connecting line between the first voltage-dividing resistor and the second voltage-dividing resistor.

10. A vehicle, characterized in that: The switching circuit comprises the switching circuit as claimed in any one of claims 1 to 9 above.

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