Protection detection circuit and coffee machine

Abstract

The utility model discloses a protection detection circuit and a coffee maker, the protection detection circuit comprises a switch unit, the first end of the switch unit is connected with a target chip, the second end of the switch unit is connected with a null line, the null line is connected with a first direct current power supply, and the switch unit can enter a conduction state under the condition of receiving a starting signal of the target chip to a target load; the single-pole double-throw switch comprises a common end, a normally-open end, a normally-closed end and a disconnecting link, the disconnecting link can enable the common end and the normally-closed end to be conducted or enable the common end and the normally-open end to be conducted, the common end is connected with the zero line, the normally-closed end is connected with the third end of the switch unit, and the fourth end of the switch unit is connected with the zero line access end of the target load. The third end and the fourth end of the switch unit are conducted after the switch unit enters the conducting state; and the first end of the signal output unit is connected with the normally open end, and the second end of the signal output unit is connected with the target chip. Therefore, the dual functions of safety protection and signal detection are realized through a simple circuit structure, and the cost is reduced.

Description

Technical Field

[0001] This application relates to the field of home appliance technology, and in particular to a protection detection circuit and a coffee machine. Background Technology

[0002] To ensure safety, some home appliances are equipped with protection and detection circuits. When a rotating component is exposed to the environment, the protection circuit immediately stops the drive of the rotating component to prevent injury to the user. The detection circuit also outputs a corresponding signal to the appliance's control chip.

[0003] Currently, protection circuits and detection circuits are generally set up separately, resulting in complex and costly circuits. For example, patent publication number CN211427106U discloses a control circuit for a dishwasher, including: a door control switch, including a normally closed door control switch, which connects or disconnects as the dishwasher door opens and closes; a door control detection circuit, connected to the door control switch, which outputs a first electrical signal when the door is closed and a second electrical signal when the door is open; a drive circuit, connected to the door control detection circuit, which amplifies the first electrical signal when it receives it; and a switching device, connected to the drive circuit, which can be controllably connected or disconnected according to the signal output by the drive circuit. The switching device connects according to the amplified first electrical signal to supply power from the mains to the dishwasher load; the drive circuit controls the switching device to disconnect when it receives the second electrical signal from the door control detection circuit to disconnect power from the mains to the load. It is evident that this circuit requires a door control switch, a door control detection circuit, a drive circuit, and a switching device, resulting in complexity and high cost. Utility Model Content

[0004] This application provides a protection detection circuit and a coffee machine. The common terminal of a single-pole double-throw switch is connected to the neutral line, the normally closed terminal of the single-pole double-throw switch is connected to the third terminal of a switching unit, the fourth terminal of the switching unit is connected to the neutral line input terminal of the target load, the normally open terminal of the single-pole double-throw switch is connected to a signal output unit, and a first DC power supply is connected to the neutral line. This reduces the complexity of the circuit while achieving safety protection and signal detection functions.

[0005] In a first aspect, a protection detection circuit is provided, comprising: a switching unit, a first end of which is connected to a target chip, a second end of which is connected to a neutral wire, the neutral wire being connected to a first DC power supply, the switching unit being able to enter a conducting state upon receiving a start signal from the target chip to a target load; a single-pole double-throw switch, comprising a common terminal, a normally open terminal, a normally closed terminal, and a disconnector, the disconnector being able to connect the common terminal to the normally closed terminal or to the normally open terminal, the common terminal being connected to the neutral wire, the normally closed terminal being connected to a third end of the switching unit, and a fourth end of the switching unit being connected to the neutral wire input terminal of the target load, the third and fourth ends of the switching unit being connected after the switching unit enters the conducting state; and a signal output unit, the first end of which is connected to the normally open terminal, and the second end of which is connected to the target chip.

[0006] In some embodiments, the switching unit includes a first transistor and a relay. The base of the first transistor is connected to a first terminal of the switching unit, the collector of the first transistor is connected to a first terminal of the coil of the relay, the emitter of the first transistor is grounded, the second terminal of the coil of the relay is a second terminal of the switching unit, the first terminal of the relay switch is a third terminal of the switching unit, and the second terminal of the relay switch is a fourth terminal of the switching unit.

[0007] By setting up a first transistor and a relay, the switching unit can be reliably switched on and off, thus ensuring the reliability of the switching unit.

[0008] In some embodiments, the switching unit further includes a diode, the anode of which is connected to a first terminal of the relay coil, and the cathode of which is connected to the neutral wire.

[0009] By incorporating a diode, the reverse electromotive force of the relay can be absorbed, thereby improving the safety of the first transistor.

[0010] In some embodiments, the switching unit further includes a first resistor and a second resistor, the base of the first transistor is connected to a first terminal of the switching unit via the first resistor, one end of the second resistor is connected to the base of the first transistor, and the other end of the second resistor is grounded.

[0011] By setting a first resistor and a second resistor, current limiting can be achieved, further improving the reliability of the switching unit.

[0012] In some embodiments, the switching unit further includes a third resistor, a fourth resistor, a fifth resistor, and a first capacitor. One end of the third resistor is connected to the first terminal of the relay switch. One end of the fourth resistor and the other end of the third resistor are connected to one end of the first capacitor. The other end of the fourth resistor is connected to one end of the fifth resistor. The other end of the fifth resistor and the other end of the first capacitor are connected to the second terminal of the relay switch.

[0013] By setting a third resistor, a fourth resistor, a fifth resistor, and a first capacitor, the sparks generated when the relay switch is turned off can be absorbed, thereby protecting the relay switch contacts and extending the relay's service life.

[0014] In some embodiments, the signal output unit includes a second transistor and a sixth resistor. The base of the second transistor is connected to a first terminal of the signal output unit, and the collector of the second transistor is the second terminal of the signal output unit. One end of the sixth resistor is connected to a second DC power supply, and the other end of the sixth resistor is connected to the collector of the second transistor. The emitter of the second transistor is grounded. This enables the signal output unit to reliably perform signal detection.

[0015] In some embodiments, the signal output unit further includes a seventh resistor, an eighth resistor, and a second capacitor. The seventh resistor is connected in series between the base of the second transistor and the first terminal of the signal output unit. One end of the eighth resistor and one end of the second capacitor are connected to the base of the second transistor, and the other end of the eighth resistor and the other end of the second capacitor are grounded.

[0016] By setting the seventh resistor, the eighth resistor, and the second capacitor, current limiting can be achieved, further improving the reliability of the signal output unit.

[0017] In some embodiments, the device further includes a fuse connected in series between the fourth terminal of the switching unit and the neutral wire connection terminal.

[0018] By installing a fuse, the power to the target load can be cut off in time when the current to the target load is too high, thus improving the safety of the target load.

[0019] In some embodiments, the fuse is a resettable fuse.

[0020] By setting the fuse to a self-resetting fuse, the power supply to the target load can be automatically restored when the current of the target load returns to the normal range, which improves the reliability of the target load and reduces maintenance costs.

[0021] In a second aspect, a coffee machine is provided, including the protection and detection circuit as described in the first aspect, and further including: a cavity capable of containing coffee beans, the cavity being provided with a cover capable of closing the cavity, wherein when the cover is in a closed state, a blade switch connects the common terminal to the normally closed terminal; and when the cover is in an open state, the blade switch connects the common terminal to the normally open terminal; a grinding assembly disposed in the cavity for grinding coffee beans; and a motor connected to the grinding assembly as the target load for driving the grinding assembly.

[0022] By applying the above technical solutions, the protection and detection circuit includes a switching unit, the first end of which is connected to the target chip, and the second end of which is connected to the neutral wire. The neutral wire is connected to the first DC power supply. The switching unit can enter the conduction state when it receives a start signal from the target chip to the target load. A single-pole double-throw switch includes a common terminal, a normally open terminal, a normally closed terminal, and a knife switch. The knife switch can connect the common terminal to the normally closed terminal or to the normally open terminal. The common terminal is connected to the neutral wire, the normally closed terminal is connected to the third terminal of the switching unit, and the fourth terminal of the switching unit is connected to the neutral wire input terminal of the target load. The third and fourth terminals of the switching unit are connected after the switching unit enters the conduction state. A signal output unit has a first end connected to the normally open terminal and a second end connected to the target chip. This enables the target load to be powered on and started when the switching unit is in the on state and the knife switch of the single-pole double-throw switch connects the common terminal and the normally closed terminal; when the knife switch of the single-pole double-throw switch connects the common terminal and the normally open terminal, the target load is powered off and stopped, and the first DC power supply is connected to the signal output unit, so that the signal output unit outputs a detection signal to the target chip. Thus, a simple circuit structure is used to achieve the dual functions of safety protection and signal detection, and the cost is reduced. Attached Figure Description

[0023] To more clearly illustrate the technical solutions of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments recorded in this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0024] Figure 1 This is a schematic diagram of the structure of a protection detection circuit according to an embodiment of this application. Figure 1 ;

[0025] Figure 2 This is a schematic diagram of the structure of a protection detection circuit according to an embodiment of this application. Figure 2 ;

[0026] Figure 3 This is a structural block diagram of a coffee machine according to an embodiment of this application. Detailed Implementation

[0027] Various embodiments and features of this application are described herein with reference to the accompanying drawings.

[0028] It should be understood that various modifications can be made to the embodiments described herein. Therefore, the above description should not be considered as limiting, but merely as an example of embodiments. Other modifications within the scope and spirit of this application will be apparent to those skilled in the art.

[0029] The accompanying drawings, which are included in and form part of this specification, illustrate embodiments of the present application and, together with the general description of the present application given above and the detailed description of the embodiments given below, serve to explain the principles of the present application.

[0030] These and other features of this application will become apparent from the following description of preferred forms of embodiments given as non-limiting examples, with reference to the accompanying drawings.

[0031] It should also be understood that although this application has been described with reference to some specific examples, those skilled in the art can certainly implement many other equivalent forms of this application.

[0032] The above and other aspects, features and advantages of this application will become more apparent when taken in conjunction with the accompanying drawings and in view of the following detailed description.

[0033] Specific embodiments of this application are described thereafter with reference to the accompanying drawings; however, it should be understood that the claimed embodiments are merely examples of this application, which can be implemented in various ways. Well-known and / or repeated functions and structures are not described in detail to avoid unnecessary or redundant details that could obscure the application. Therefore, the specific structural and functional details claimed herein are not intended to be limiting, but merely serve as the basis and representative basis for the claims to teach those skilled in the art to use this application in a variety of substantially any suitable detailed structures.

[0034] This specification may use the phrases “in one embodiment,” “in another embodiment,” “in yet another embodiment,” or “in other embodiments,” all of which may refer to one or more of the same or different embodiments according to this application.

[0035] An embodiment of this application provides a protection and detection circuit that uses a single-pole double-throw (SPD) switch. The common terminal of the SPD switch is connected to the neutral wire, the normally closed terminal of the SPD switch is connected to the third terminal of a switching unit, the fourth terminal of the switching unit is connected to the neutral wire input terminal of the target load, and the normally open terminal of the SPD switch is connected to a signal output unit. A first DC power supply is connected to the neutral wire. This allows the target load to be powered on and started when the switching unit is in the ON state and the SPD switch's switch connects the common terminal to the normally closed terminal. When the SPD switch's switch connects the common terminal to the normally open terminal, the target load is powered off and stopped. The first DC power supply is then connected to the signal output unit, which outputs a detection signal to the target chip. This simple circuit structure achieves both safety protection and signal detection functions while reducing costs.

[0036] like Figure 1 As shown, the protection detection circuit includes:

[0037] The switching unit 100 has a first end connected to the target chip 200 and a second end connected to the neutral line N, which is connected to the first DC power supply. The switching unit 100 can enter the conduction state when it receives the start signal from the target chip 200 to the target load 300.

[0038] The single-pole double-throw switch SW includes a common terminal 2, a normally open terminal 3, a normally closed terminal 1, and a disconnector. The disconnector enables the common terminal 2 to conduct with the normally closed terminal 1 or to conduct with the normally open terminal 3. The common terminal 2 is connected to the neutral wire N. The normally closed terminal 1 is connected to the third terminal of the switch unit 100. The fourth terminal of the switch unit 100 is connected to the neutral wire input terminal of the target load 300. The third and fourth terminals of the switch unit 100 conduct after the switch unit 100 enters the conducting state.

[0039] The signal output unit 400 has its first end connected to the normally open terminal 3 and its second end connected to the target chip 200.

[0040] In this embodiment, the target chip 200 can be an MCU (Microcontroller Unit), and the target load 300 is connected to a live wire via a live wire access terminal. The target chip 200 sends a start signal to the switching unit 100 to enable the switching unit 100 to enter the conducting state, thereby connecting the target load 300 to the neutral line N via the fourth and third terminals of the switching unit 100, the normally closed terminal 1 and the common terminal 2 of the single-pole double-throw switch SW, and the target load 300 is powered on and started. If, during the operation of the target load 300, the single-pole double-throw switch SW activates, connecting the common terminal 2 and the normally open terminal 3, then the target load 300 is disconnected from the neutral line N, causing the target load 300 to stop and thus achieving the protection function. Simultaneously, since the neutral line N is connected to the first DC power supply, the signal output unit 400 is connected to the first DC power supply via the normally open terminal 3 and the common terminal 2 of the single-pole double-throw switch SW. The signal output unit 400 sends a detection signal to the target chip 200, which then sends a corresponding alarm signal, thus achieving the signal detection function.

[0041] It should be noted that since the first DC power supply is connected to the neutral wire, it does not form a circuit with the live wire, so it will not affect the normal operation of the circuit. In some embodiments of this application, the first DC power supply is 5V.

[0042] The protection detection circuit of this application embodiment includes a switching unit 100, a first end of which is connected to a target chip 200, a second end of which is connected to a neutral line N, and a first DC power supply. The switching unit 100 can enter a conducting state when it receives a start signal from the target chip 200 to the target load 300. A single-pole double-throw switch SW includes a common terminal 2, a normally open terminal 3, a normally closed terminal 1, and a knife switch. The knife switch can connect the common terminal 2 to the normally closed terminal 1 or connect the common terminal 2 to the normally open terminal 3. The common terminal 2 is connected to the neutral line N, the normally closed terminal 1 is connected to the third end of the switching unit 100, and the fourth end of the switching unit 100 is connected to the neutral line input terminal of the target load 300. The third and fourth ends of the switching unit 100 are connected after the switching unit 100 enters the conducting state. A signal output unit 400 has a first end connected to the normally open terminal 3 and a second end connected to the target chip 200. This enables the target load 300 to be powered on and started when the switch unit 100 is in the conducting state and the single-pole double-throw switch SW connects the common terminal 2 with the normally closed terminal 1; when the single-pole double-throw switch SW connects the common terminal 2 with the normally open terminal 3, the target load 300 is powered off and stopped, and the first DC power supply is connected to the signal output unit 400, so that the signal output unit 400 outputs a detection signal to the target chip 200. Thus, the dual functions of safety protection and signal detection are achieved with a simple circuit structure, and the cost is reduced.

[0043] In some embodiments of this application, such as Figure 2 As shown, the switching unit 100 includes a first transistor Q1 and a relay RLY1. The base of the first transistor Q1 is connected to the first terminal of the switching unit 100. The collector of the first transistor Q1 is connected to the first terminal of the coil of the relay RLY1. The emitter of the first transistor Q1 is grounded. The second terminal of the coil of the relay RLY1 is the second terminal of the switching unit 100. The first terminal of the switch of the relay RLY1 is the third terminal of the switching unit 100. The second terminal of the switch of the relay RLY1 is the fourth terminal of the switching unit 100.

[0044] In this embodiment, if the target chip 200 sends a start signal to the target load 300 through a first pin (such as the CPUMP pin), the collector and emitter of the first transistor Q1 are turned on, thereby energizing the coil of the relay RLY1. This, in turn, turns on the first and second terminals of the relay RLY1 switch, and the switching unit 100 enters the on state. If the target chip 200 sends a stop signal to the target load 300 through the first pin, the collector and emitter of the first transistor Q1 are turned off, thereby de-energizing the coil of the relay RLY1. This, in turn, turns off the relay RLY1 switch, and the switching unit 100 enters the off state.

[0045] By setting the first transistor Q1 and the relay RLY1, the switching unit 100 can be reliably switched on and off, thus ensuring the reliability of the switching unit 100.

[0046] Optionally, the relay RLY1 in the switching unit 100 can also be a contactor.

[0047] In some embodiments of this application, such as Figure 2 As shown, the switching unit 100 also includes a diode D1, the anode of which is connected to the first terminal of the coil of the relay RLY1, and the cathode of which is connected to the neutral line N.

[0048] In this embodiment, by setting diode D1, the reverse electromotive force of relay RLY1 can be absorbed, thereby improving the safety of the first transistor Q1.

[0049] In some embodiments of this application, such as Figure 2 As shown, the switching unit 100 also includes a first resistor R1 and a second resistor R2. The base of the first transistor Q1 is connected to the first terminal of the switching unit 100 via the first resistor R1. One end of the second resistor R2 is connected to the base of the first transistor Q1, and the other end of the second resistor R2 is grounded.

[0050] In this embodiment, by setting the first resistor R1 and the second resistor R2, current limiting can be achieved, further improving the reliability of the switching unit 100.

[0051] In some embodiments of this application, such as Figure 2 As shown, the switching unit 100 also includes a third resistor R3, a fourth resistor R4, a fifth resistor R5, and a first capacitor C1. One end of the third resistor R3 is connected to the first terminal of the switch of the relay RLY1. One end of the fourth resistor R4 and the other end of the third resistor R3 are connected to one end of the first capacitor C1. The other end of the fourth resistor R4 is connected to one end of the fifth resistor R5. The other end of the fifth resistor R5 and the other end of the first capacitor C1 are connected to the second terminal of the switch of the relay RLY1.

[0052] In this embodiment, by setting a third resistor R3, a fourth resistor R4, a fifth resistor R5 and a first capacitor C1, the spark generated when the relay RLY1 is switched off can be absorbed, thereby protecting the contacts of the relay RLY1 and extending the service life of the relay RLY1.

[0053] In some embodiments of this application, such as Figure 2 As shown, the signal output unit 400 includes a second transistor Q2 and a sixth resistor R6. The base of the second transistor Q2 is connected to the first terminal of the signal output unit 400, and the collector of the second transistor Q2 is the second terminal of the signal output unit 400. One end of the sixth resistor R6 is connected to the second DC power supply, and the other end of the sixth resistor R6 is connected to the collector of the second transistor Q2. The emitter of the second transistor Q2 is grounded.

[0054] In this embodiment, when the common terminal 2 and normally open terminal 3 of the single-pole double-throw switch SW are connected, the first DC power supply turns on the collector and emitter of the second transistor Q2. Since the collector of the second transistor Q2 is connected to the second DC power supply through the sixth resistor R6, the collector of the second transistor Q2 changes from low level to high level and is output to the second pin (such as the VD pin) of the target chip 200. The target chip 200 generates a detection alarm signal according to the signal of the second pin, so that the signal output unit 400 can reliably realize the signal detection function.

[0055] In some embodiments of this application, the second DC power supply is +5V.

[0056] In some embodiments of this application, such as Figure 2As shown, the signal output unit 400 also includes a seventh resistor R7, an eighth resistor R8, and a second capacitor C2. The seventh resistor R7 is connected in series between the base of the second transistor Q2 and the first terminal of the signal output unit 400. One end of the eighth resistor R8 and one end of the second capacitor C2 are connected to the base of the second transistor Q2, and the other end of the eighth resistor R8 and the other end of the second capacitor C2 are grounded.

[0057] By setting the seventh resistor R7, the eighth resistor R8, and the second capacitor C2, current limiting can be achieved, further improving the reliability of the signal output unit 400.

[0058] In some embodiments of this application, such as Figure 2 As shown, it also includes:

[0059] The fuse FUSE is connected in series between the fourth terminal of the switch unit 100 and the neutral wire connection terminal.

[0060] The target load 300 is connected to the live wire L through the live wire access terminal. By setting the fuse FUSE, the power to the target load 300 can be cut off in time when the current of the target load 300 is too high, thereby improving the safety of the target load 300.

[0061] In some embodiments of this application, the fuse FUSE is a resettable fuse.

[0062] By setting the fuse FUSE to a self-resetting fuse, the power supply to the target load 300 can be automatically restored when the current of the target load 300 returns to the normal range, thereby improving the reliability of the target load 300 and reducing maintenance costs.

[0063] This application also proposes a coffee machine, such as... Figure 3 As shown, the protection detection circuit, including embodiments of this application, further includes:

[0064] A cavity capable of holding coffee beans, the cavity being provided with a cover capable of closing the cavity; when the cover is in the closed state, the common terminal is connected to the normally closed terminal via a knife switch; when the cover is in the open state, the common terminal is connected to the normally open terminal via the knife switch.

[0065] A grinding assembly, disposed within the cavity, is used to grind coffee beans;

[0066] A motor, connected to the grinding assembly as the target load, is used to drive the grinding assembly.

[0067] In this embodiment, if the cover on the cavity is opened during the operation of the motor-driven grinding assembly, the common terminal and normally open terminal of the single-pole double-throw switch are connected, and the motor is disconnected from the neutral line, causing the motor to stop and thus achieving the protection function. At the same time, since the first DC power supply is connected to the neutral line, the signal output unit is connected to the first DC power supply through the normally open terminal and the common terminal of the single-pole double-throw switch, and the signal output unit sends a detection alarm signal to the target chip, thereby achieving the signal detection function.

[0068] The coffee machine of this embodiment includes a protection detection circuit; a cavity capable of holding coffee beans, with a cover on the cavity for closing the cavity; when the cover is closed, a knife switch connects the common terminal to the normally closed terminal; when the cover is open, a knife switch connects the common terminal to the normally open terminal; a grinding assembly is disposed in the cavity for grinding coffee beans; and a motor is connected to the grinding assembly as a target load for driving the grinding assembly. By combining the cavity cover with a single-pole double-throw switch, when the cover is open, the common terminal of the single-pole double-throw switch is connected to the normally open terminal, thus disconnecting the motor from the neutral wire, stopping the motor, and connecting the first DC power supply to the signal output unit, causing the signal output unit to output a detection signal to the target chip. This achieves both safety protection and signal detection functions with a simple circuit structure and reduces costs.

[0069] Furthermore, although exemplary embodiments have been described herein, their scope includes any and all embodiments based on this disclosure that have equivalent elements, modifications, omissions, combinations (e.g., schemes involving intersections of various embodiments), adaptations, or alterations. Elements in the claims will be interpreted broadly based on the language used in the claims and are not limited to the examples described in this specification or during the implementation of this application, and such examples will be interpreted as non-exclusive. Therefore, this specification and examples are intended to be considered illustrative only, and the true scope and spirit are indicated by the full scope of the following claims and their equivalents.

[0070] The above description is intended to be illustrative and not restrictive. For example, the above examples (or one or more thereof) can be used in combination with each other. Other embodiments may be used by those skilled in the art upon reading the above description. Furthermore, in the above detailed description, various features may be grouped together to simplify the disclosure. This should not be construed as an intention that a feature of the disclosure that is not claimed is necessary for any claim. Rather, the subject matter of this disclosure may be less than all the features of a particular disclosed embodiment. Thus, the following claims are incorporated herein by reference as examples or embodiments, wherein each claim is an independent, separate embodiment, and these embodiments are contemplated to be combined with each other in various combinations or arrangements. The scope of this disclosure should be determined by reference to the appended claims and the full scope of their equivalents.

[0071] The foregoing has provided a detailed description of several embodiments of this disclosure. However, this disclosure is not limited to these specific embodiments. Those skilled in the art can make various variations and modifications based on the concept of this disclosure, and all such variations and modifications should fall within the scope of protection claimed by this disclosure.

Claims

1. A protection detection circuit, characterized in that, include: A switching unit, wherein a first end of the switching unit is connected to a target chip, a second end of the switching unit is connected to a neutral wire, the neutral wire is connected to a first DC power supply, and the switching unit can enter a conducting state upon receiving a start signal from the target chip to the target load; A single-pole double-throw switch includes a common terminal, a normally open terminal, a normally closed terminal, and a disconnector. The disconnector enables the common terminal to conduct with the normally closed terminal or with the normally open terminal. The common terminal is connected to the neutral wire. The normally closed terminal is connected to the third terminal of the switch unit. The fourth terminal of the switch unit is connected to the neutral wire input terminal of the target load. The third and fourth terminals of the switch unit conduct after the switch unit enters the conducting state. A signal output unit, wherein the first end of the signal output unit is connected to the normally open terminal, and the second end of the signal output unit is connected to the target chip.

2. The protection detection circuit as described in claim 1, characterized in that, The switching unit includes a first transistor and a relay. The base of the first transistor is connected to the first terminal of the switching unit, the collector of the first transistor is connected to the first terminal of the coil of the relay, the emitter of the first transistor is grounded, the second terminal of the coil of the relay is the second terminal of the switching unit, the first terminal of the relay switch is the third terminal of the switching unit, and the second terminal of the relay switch is the fourth terminal of the switching unit.

3. The protection detection circuit as described in claim 2, characterized in that, The switching unit also includes a diode, the anode of which is connected to the first terminal of the relay coil, and the cathode of which is connected to the neutral wire.

4. The protection detection circuit as described in claim 2, characterized in that, The switching unit further includes a first resistor and a second resistor. The base of the first transistor is connected to the first terminal of the switching unit via the first resistor. One end of the second resistor is connected to the base of the first transistor, and the other end of the second resistor is grounded.

5. The protection detection circuit as described in claim 2, characterized in that, The switching unit further includes a third resistor, a fourth resistor, a fifth resistor, and a first capacitor. One end of the third resistor is connected to the first terminal of the relay switch. One end of the fourth resistor and the other end of the third resistor are connected to one end of the first capacitor. The other end of the fourth resistor is connected to one end of the fifth resistor. The other end of the fifth resistor and the other end of the first capacitor are connected to the second terminal of the relay switch.

6. The protection detection circuit as described in claim 1, characterized in that, The signal output unit includes a second transistor and a sixth resistor. The base of the second transistor is connected to the first terminal of the signal output unit, and the collector of the second transistor is the second terminal of the signal output unit. One end of the sixth resistor is connected to a second DC power supply, and the other end of the sixth resistor is connected to the collector of the second transistor. The emitter of the second transistor is grounded.

7. The protection detection circuit as described in claim 6, characterized in that, The signal output unit further includes a seventh resistor, an eighth resistor, and a second capacitor. The seventh resistor is connected in series between the base of the second transistor and the first terminal of the signal output unit. One end of the eighth resistor and one end of the second capacitor are connected to the base of the second transistor, and the other end of the eighth resistor and the other end of the second capacitor are grounded.

8. The protection detection circuit as described in claim 1, characterized in that, Also includes: A fuse, which is connected in series between the fourth terminal of the switch unit and the neutral wire connection terminal.

9. The protection detection circuit as described in claim 8, characterized in that, The fuse is a resettable fuse.

10. A coffee machine, characterized in that, Including the protection detection circuit as described in claim 1, it further includes: A cavity capable of holding coffee beans, the cavity being provided with a cover capable of closing the cavity; when the cover is in the closed state, the common terminal is connected to the normally closed terminal via a knife switch; when the cover is in the open state, the common terminal is connected to the normally open terminal via the knife switch. A grinding assembly, disposed within the cavity, is used to grind coffee beans; A motor, connected to the grinding assembly as the target load, is used to drive the grinding assembly.

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