Food processor
By introducing protective resistors, especially thermistors, into the control circuit of the food processor, the problem of relay arcing caused by vibration and external interference during the forward and reverse switching of the food processor is solved, improving the reliability and safety of the circuit and adapting to the DC motor speeds of different load requirements.
Patent Information
- Application Number
- CN202520131599.6
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2025-01-20
- Publication Date
- 2026-02-03
- Estimated Expiration
- 2035-01-20
AI Technical Summary
Existing food processing machines are prone to relay arcing due to vibration and external interference during forward and reverse switching, posing a safety hazard and making the control circuit easily damaged.
Introducing protective resistors, especially positive and negative temperature coefficient thermistors, into the control circuit absorbs surge currents, protects other components in the control circuit, and improves circuit reliability and shock resistance.
It effectively prevents relay arcing, protects the control circuit from damage, improves the safety and reliability of food processing machines, and adapts to the DC motor speed required by different loads.
Smart Images
Figure CN223872220U_ABST
Abstract
Description
Technical Field
[0001] This disclosure relates to the field of food processing technology, and in particular to a food processing machine. Background Technology
[0002] In existing food processing machines, such as noodle makers, meat grinders, and juicers, the motor needs to switch between forward and reverse rotation. DC motors are commonly used. In the control circuits that control the operation of DC motors, the forward and reverse rotation switching of DC motors is usually controlled by two relays plus a thyristor.
[0003] However, existing food processing machines have the following problems: On the one hand, food processing machines generate vibrations during operation. For example, during the operation of a noodle machine, the cup assembly used for noodle processing may be affected by the squeezing force when extruding noodles, thereby causing the base equipped with control circuitry to vibrate; during the operation of a meat grinder, the motor speed is high, and the vibration of the motor may cause the base equipped with control circuitry to vibrate; during the operation of a juicer, the cup assembly used for juicing food may be affected by the squeezing force when extruding food, thereby causing the base equipped with control circuitry to vibrate. On the other hand, food processing machines may be subject to external interference during operation; for example, a food processing machine may be moved or collided with during operation. Because relays have weak shock resistance, when a food processor is subjected to external vibration during forward and reverse switching via a relay, the free end of the relay's single-pole double-throw switch can easily swing back and forth between the two stationary contacts, causing arcing. This can lead to relay sparking, motor bypass, and short circuits in the positive and negative outputs of the rectifier bridge, causing the thyristor to break down and the fuse to burn out, resulting in damage to the food processor and posing a safety hazard.
[0004] Therefore, there is an urgent need to propose a food processing machine that can at least solve the technical problems of relay ignition during and after the forward and reverse switching of food processing machines in the existing technology. Utility Model Content
[0005] In order to solve the above-mentioned technical problems, or at least partially solve the above-mentioned technical problems, this disclosure provides a food processing machine to at least solve the technical problem that in the prior art, food processing machines with forward and reverse functions are prone to relay arcing during and after the forward and reverse switching process under strong vibration.
[0006] This disclosure provides a food processing machine, including: a DC motor and a control circuit for controlling the forward and reverse operation of the DC motor. The control circuit includes a rectifier and a first relay and a second relay that cooperate to control the forward and reverse operation of the DC motor. The first relay includes a first free terminal connected to the negative output terminal of the rectifier and a second free terminal connected to the positive output terminal of the rectifier. The first free terminal and the second free terminal of the first relay are selectively connected to the positive terminal of the DC motor. The second relay includes a first free terminal connected to the positive output terminal of the rectifier and a second free terminal connected to the negative output terminal of the rectifier. The first free terminal and the second free terminal of the second relay are selectively connected to the negative terminal of the DC motor. A protective resistor is provided between the first free terminal of the first relay and the negative output terminal of the rectifier, and between the first free terminal of the second relay and the positive output terminal of the rectifier.
[0007] Optionally, the food processor is configured such that the current passing through the protective resistor during operation is greater than or equal to 22A, and the protective resistor is a positive temperature coefficient thermistor.
[0008] Optionally, the food processor is configured such that the current passing through the protective resistor during operation is less than 22A, and the protective resistor is a negative temperature coefficient thermistor.
[0009] Optionally, both the first and second relays are relays equipped with a single-pole double-throw switch.
[0010] Optionally, the first relay includes one moving contact and two stationary contacts. The moving contact of the first relay is connected to the positive terminal of the DC motor. One of the stationary contacts of the first relay is a second free terminal connected to the positive output terminal of the rectifier, and the other stationary contact is a first free terminal connected to the negative output terminal of the rectifier. The second relay includes one moving contact and two stationary contacts. The moving contact of the second relay is connected to the negative terminal of the DC motor. One of the stationary contacts of the second relay is a first free terminal connected to the positive output terminal of the rectifier, and the other stationary contact is a second free terminal connected to the negative output terminal of the rectifier.
[0011] Optionally, the protection resistor includes a first protection resistor connected between the first free terminal of the second relay and the positive output terminal of the rectifier. The first relay and the first protection resistor are respectively connected in series at both ends of the DC motor, and the two intersect to form a first node. The first node is connected to the positive output terminal of the rectifier.
[0012] Optionally, the first protective resistor is located between the first node and the first free end of the second relay.
[0013] Optionally, the protection resistor includes a second protection resistor connected between the first free terminal of the first relay and the negative output terminal of the rectifier. The second relay and the second protection resistor are connected in series at both ends of the DC motor, and the two intersect to form a second node. The second node is connected to the negative output terminal of the rectifier.
[0014] Optionally, the second protection resistor is located between the second node and the first free end of the first relay.
[0015] Optionally, the protection resistor can be set to a positive temperature coefficient thermistor with a resistance of 2-3Ω at room temperature; or, the protection resistor can be set to a negative temperature coefficient thermistor with a resistance of 10-20Ω at room temperature.
[0016] The technical solution provided in this disclosure has the following advantages compared with the prior art:
[0017] 1. In the food processing machine provided in this disclosure, a protective resistor is provided between the first free terminal of the first relay and the negative output terminal of the rectifier in the control circuit. This protects the food processing machine from being damaged by a surge current caused by arcing and oscillation of the contacts in the first relay. Similarly, a protective resistor is provided between the first free terminal of the second relay and the positive output terminal of the rectifier in the control circuit. This protects the food processing machine from being damaged by a surge current caused by arcing and oscillation of the contacts in the second relay.
[0018] 2. The food processor is designed to handle a current through the protective resistor of 22A or greater during operation. This protective resistor is a positive temperature coefficient thermistor. When the food processor vibrates or is subjected to external interference, the control circuit may generate inrush current, which can further increase the ambient temperature. Furthermore, the fact that the current through the protective resistor is greater than or equal to 22A during normal operation means that the DC motor in the food processor has a relatively low speed requirement and a low load capacity requirement. Therefore, even with a higher resistance value for the protective resistor, the DC motor's load capacity can still meet the requirements.
[0019] 3. The food processor is designed to handle a current of less than 22A through the protective resistor during operation. The protective resistor is a negative temperature coefficient (NTC) thermistor. During normal operation, vibration or external interference may cause surge currents in the control circuit. The NTC thermistor absorbs and limits these surge currents, protecting other components in the control circuit. Furthermore, the resistance of the NTC thermistor decreases as the ambient temperature increases. During normal operation, the ambient temperature is relatively high. At this temperature, the lower resistance of the NTC thermistor results in a smaller voltage drop, minimizing its impact on the DC motor's load capacity and thus meeting the DC motor's load requirements during normal operation.
[0020] 4. Both the first and second relays are relays equipped with single-pole double-throw switches, which not only provide flexible circuit switching functions, but also have many advantages such as high reliability, low power consumption, fast response, and easy control, which helps to improve the reliability of the control circuit.
[0021] A second protective resistor is provided between the negative output terminal of the rectifier and the stationary contact of the first relay. When the DC motor switches from reverse to forward rotation, or during forward rotation, if the food processor vibrates or is disturbed by external forces, the free end of the single-pole double-throw switch of the first relay swings back and forth between the two stationary contacts, causing an inrush current. The second protective resistor can absorb the inrush current, preventing it from damaging other components in the control circuit and causing damage to the food processor.
[0022] A first protective resistor is connected between the positive output terminal of the rectifier and the stationary contact of the second relay. When the DC motor switches from forward to reverse, or during the reverse process, if the food processor vibrates or is disturbed by external forces, the free end of the single-pole double-throw switch of the second relay swings back and forth between the two stationary contacts, causing an inrush current. The first protective resistor can absorb the inrush current to prevent it from damaging other components in the control circuit and causing damage to the food processor.
[0023] 5. The protection resistor can be set to a positive temperature coefficient thermistor with a resistance of 2-3Ω at room temperature. The positive temperature coefficient thermistor has a small resistance at room temperature, which avoids the positive temperature coefficient thermistor from becoming too large due to the influence of the high ambient temperature environment when the food processing machine is running normally, thus affecting the load capacity of the DC motor.
[0024] The protective resistor can be set as a negative temperature coefficient thermistor with a room temperature resistance of 10-20Ω. When the food processing machine vibrates or is subjected to external interference, the control circuit may generate surge current. The generation of surge current will lead to a higher ambient temperature. The negative temperature coefficient thermistor has a larger room temperature resistance, thereby avoiding the influence of the higher ambient temperature environment when the control circuit generates surge current, which would cause the resistance of the negative temperature coefficient thermistor to be too small, thus affecting the absorption and limitation of surge current by the negative temperature coefficient thermistor. Attached Figure Description
[0025] The accompanying drawings, which are incorporated in and form a part of this specification, illustrate embodiments consistent with this disclosure and, together with the description, serve to explain the principles of this disclosure.
[0026] To more clearly illustrate the technical solutions in the embodiments of this disclosure or the prior art, the accompanying drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, for those skilled in the art, other drawings can be obtained based on these drawings without creative effort.
[0027] Figure 1 This is a circuit diagram of a control circuit in a food processing machine provided in this disclosure;
[0028] Figure 2 yes Figure 1 A schematic diagram of the control circuit when the DC motor is rotating in the forward direction;
[0029] Figure 3 yes Figure 1 A schematic diagram of the control circuit in the reverse state of the DC motor;
[0030] Figure 4 yes Figure 1 A schematic diagram showing the swinging and arcing phenomenon of the first relay in the control circuit when the DC motor is rotating in the forward direction;
[0031] Figure 5 yes Figure 1 The diagram shows the control circuit where the second relay swings and arcs when the DC motor is in reverse rotation. Detailed Implementation
[0032] To better understand the above-mentioned objectives, features, and advantages of this disclosure, the solutions disclosed herein will be further described below. It should be noted that, unless otherwise specified, the embodiments and features described herein can be combined with each other.
[0033] Numerous specific details are set forth in the following description in order to provide a full understanding of this disclosure, but this disclosure may also be implemented in other ways different from those described herein; obviously, the embodiments in the specification are only some, and not all, of the embodiments of this disclosure.
[0034] This disclosure provides a food processing machine, which includes a DC motor and a control circuit for controlling the forward and reverse operation of the DC motor. Figure 1 This is a circuit diagram of a control circuit in a food processing machine provided in this disclosure, for reference. Figure 1 The control circuit includes a rectifier DB1 and a first relay RL1 and a second relay RL2 that work together to control the forward and reverse operation of the DC motor. The first relay RL1 includes a first free terminal connected to the negative output terminal of the rectifier DB1 and a second free terminal connected to the positive output terminal of the rectifier DB1. The first free terminal and the second free terminal of the first relay RL1 are selectively connected to the positive terminal of the DC motor. The second relay RL2 includes a first free terminal connected to the positive output terminal of the rectifier DB1 and a second free terminal connected to the negative output terminal of the rectifier DB1. The first free terminal and the second free terminal of the second relay RL2 are selectively connected to the negative terminal of the DC motor. A protective resistor R is provided between the first free terminal of the first relay RL1 and the negative output terminal of the rectifier DB1, and between the first free terminal of the second relay RL2 and the positive output terminal of the rectifier DB1.
[0035] Wherein, the first free terminal and the second free terminal of the first relay RL1 are respectively Figure 1 The first relay RL1 has contacts 3 and 2. The second relay RL2 has its first free terminal and second free terminal respectively. Figure 1 Contacts 2 and 3 of the second relay RL2.
[0036] Regarding the above technical solution, the food processing machine has three states. The first state is when the DC motor is not working. (Continue to refer to...) Figure 1 At this time, the first free terminal of the first relay RL1 is connected to the positive terminal of the DC motor, thus the positive output terminal of the rectifier DB1 is connected to the positive terminal of the DC motor through the first relay RL1. The first free terminal of the second relay RL2 is connected to the negative terminal of the DC motor, thus the positive output terminal of the rectifier DB1 is connected to the negative terminal of the DC motor through the second relay RL2. The control circuit also includes a switch control circuit 10, which is connected in series between the positive terminal of the power supply and the rectifier DB1. At this time, the switch control circuit 10 is not conducting, no circuit loop is formed, and therefore the DC motor does not work.
[0037] The second state is when the DC motor is rotating in the forward direction. Figure 2 yes Figure 1A schematic diagram of the control circuit when the DC motor is rotating forward is shown below. Figure 2 At this time, the second free terminal of the first relay RL1 is connected to the positive terminal of the DC motor, the positive output terminal of the rectifier DB1 is connected to the positive terminal of the DC motor through the first relay RL1, the second free terminal of the second relay RL2 is connected to the negative terminal of the DC motor, the negative output terminal of the rectifier DB1 is connected to the negative terminal of the DC motor through the second relay RL2, the switch control circuit 10 is turned on, thus forming a circuit loop, and the DC motor rotates forward.
[0038] The third state is the DC motor reversing. Figure 3 yes Figure 1 A schematic diagram of the control circuit in the reverse rotation state of the DC motor is shown below. Figure 3 At this time, the first free end of the first relay RL1 is connected to the positive terminal of the DC motor, the negative output terminal of the rectifier DB1 is connected to the positive terminal of the DC motor through the first relay RL1, the first free end of the second relay RL2 is connected to the negative terminal of the DC motor, the positive output terminal of the rectifier DB1 is connected to the negative terminal of the DC motor through the second relay RL2, the switch control circuit 10 is turned on, thus forming a circuit loop, and the DC motor reverses.
[0039] The first relay RL1 and the second relay RL2 have weak shock resistance. When the food processing machine vibrates or is subjected to external interference, relay arcing is prone to occur during and after the forward / reverse switching process. For details, please refer to... Figure 4 , Figure 4 yes Figure 1 The diagram illustrates the swinging arcing phenomenon of the first relay in the control circuit when the DC motor is rotating forward. When the food processor is in the second state, i.e. the DC motor is rotating forward, and the food processor vibrates or is disturbed by external forces, the contacts in the first relay RL1 will swing and arc, causing a surge current. The surge current may damage other components in the control circuit, causing damage to the food processor.
[0040] In the food processing machine provided in this disclosure, a protective resistor R is provided between the first free terminal of the first relay RL1 in the control circuit and the negative output terminal of the rectifier DB1. When the contacts in the first relay RL1 swing and arc, causing a surge current, the protective resistor R can absorb the surge current, preventing the surge current from damaging other components in the control circuit and causing damage to the food processing machine.
[0041] Similarly, refer to Figure 5 , Figure 5 yes Figure 1The diagram illustrates the swinging arcing phenomenon of the second relay in the control circuit when the DC motor is in reverse. When the food processor is in the third state, i.e. the DC motor is in reverse, and the food processor vibrates or is disturbed by external forces, the contacts in the second relay RL2 will swing and arc, causing a surge current. The surge current may damage other components in the control circuit, causing damage to the food processor.
[0042] In the food processing machine provided in this disclosure, a protective resistor R is provided between the first free terminal of the second relay RL2 in the control circuit and the positive output terminal of the rectifier DB1. When the contacts in the second relay RL2 swing and arc, causing a surge current, the protective resistor R can absorb the surge current, preventing the surge current from damaging other components in the control circuit and causing damage to the food processing machine.
[0043] The above technical solution solves the technical problem that in existing food processing machines with forward and reverse rotation functions, relay sparking easily occurs during and after the forward and reverse rotation switching process under strong vibration.
[0044] For the above technical solutions, the food processing machine can be a noodle machine, meat grinder, juicer, or other food processing machine that requires a control circuit to control the forward and reverse rotation of a DC motor.
[0045] When a food processor is set to operate with a current through the protective resistor greater than or equal to 22A, it means that the DC motor in the food processor has a low speed requirement and a low load capacity requirement. Even with a relatively large resistance value, the load capacity of the DC motor can still be met. For example, this food processor could be a noodle maker, a juicer, etc.
[0046] Continue to refer to Figure 1 Optionally, the food processor is configured such that the current passing through the protection resistor R during operation is greater than or equal to 22A, and the protection resistor R is a positive temperature coefficient thermistor.
[0047] Specifically, when a food processor is operating normally, if it vibrates or is subjected to external interference, the control circuit will generate a surge current, which will cause the ambient temperature to rise.
[0048] Using the above technical solution, the protective resistor R can be a positive temperature coefficient (PTC) thermistor. As the ambient temperature increases, the resistance of the PTC thermistor increases. During normal operation of the food processing machine, the ambient temperature is relatively high. When the food processing machine vibrates or is subjected to external interference, the control circuit may generate surge current. The generation of surge current causes the ambient temperature to rise further. In this case, the higher resistance of the PTC thermistor helps absorb and limit the surge current, protecting other components in the control circuit.
[0049] Furthermore, when the food processor is running normally, the current passing through the protection resistor R is greater than or equal to 22A, which means that the speed requirement of the DC motor in the food processor is low and the load capacity requirement of the DC motor is not high. At this time, even if the resistance value of the protection resistor R is high, the load capacity of the DC motor can still meet the requirements.
[0050] For example, a food processor that is designed to have a current greater than or equal to 22A passing through the protective resistor R during operation can be a noodle maker, juicer, or other food processor. In this type of food processor, the protective resistor R is a positive temperature coefficient thermistor.
[0051] Optionally, the protection resistor R is set to a positive temperature coefficient thermistor with a resistance of 2-3Ω at room temperature.
[0052] By adopting the above technical solution, the resistance of the positive temperature coefficient thermistor at room temperature is relatively small, thereby avoiding the influence of the high ambient temperature environment during normal operation of the food processing machine, which would cause the resistance of the positive temperature coefficient thermistor to be too large and affect the load capacity of the DC motor.
[0053] When a food processor is configured such that the current passing through the protective resistor is less than 22A during operation, it means that the DC motor in this food processor requires a high speed and a high load capacity. If the resistance of the protective resistor is large, it can easily cause the DC motor's load capacity to be insufficient to meet the requirements. For example, this food processor could be a meat grinder, etc.
[0054] Continue to refer to Figure 1 Optionally, the food processor can be configured such that the current passing through the protection resistor R during operation is less than 22A, and the protection resistor R is a negative temperature coefficient thermistor.
[0055] Specifically, when the current through the protection resistor R is less than 22A during normal operation of the food processor, it means that the DC motor in the food processor requires a high speed and a high load capacity.
[0056] Using the above technical solution, when the food processing machine is working normally, if the food processing machine vibrates or is disturbed by external forces, the control circuit may generate surge current. The negative temperature coefficient thermistor can absorb and limit the surge current to a certain extent, thereby protecting other components in the control circuit.
[0057] As the ambient temperature rises, the resistance of a negative temperature coefficient thermistor decreases. During normal operation of a food processing machine, the ambient temperature is relatively high. At this temperature, the resistance of the negative temperature coefficient thermistor is low, resulting in a smaller voltage drop across it and less impact on the load capacity of the DC motor. This allows the load requirements of the DC motor to be met during normal operation of the food processing machine.
[0058] For example, a food processor set to have a current of less than 22A passing through the protective resistor R during operation can be a meat grinder or other food processors. In this type of food processor, the protective resistor R is a negative temperature coefficient thermistor.
[0059] Optionally, the protection resistor R is set to a negative temperature coefficient thermistor with a resistance of 10-20Ω at room temperature.
[0060] When the food processing machine vibrates or is subjected to external interference, the control circuit may generate surge current. The generation of surge current will lead to a higher ambient temperature. The negative temperature coefficient thermistor has a larger resistance value at room temperature, thus avoiding the negative temperature coefficient thermistor's resistance value being too small due to the influence of the higher ambient temperature environment when the control circuit generates surge current, which would affect the absorption and limitation function of the negative temperature coefficient thermistor for surge current.
[0061] Continue to refer to Figure 1 Optionally, the control circuit also includes a first relay control circuit 21 for controlling the switching of the first relay RL1 between the positive and negative output terminals of the rectifier DB1, and a second relay control circuit 22 for controlling the switching of the second relay RL2 between the positive and negative output terminals of the rectifier DB1; the positive and negative terminals of the DC motor are connected to the first relay RL1 and the second relay RL2, respectively.
[0062] Using the above technical solution, the positive terminal of the DC motor is connected to the first relay RL1. The first relay control circuit can control the first relay RL1 to switch between the positive and negative output terminals of the rectifier DB1, thereby connecting the positive terminal of the DC motor to either the positive or negative output terminal of the rectifier DB1. The negative terminal of the DC motor is connected to the second relay RL2. The second relay control circuit can control the second relay RL2 to switch between the positive and negative output terminals of the rectifier DB1, thereby connecting the negative terminal of the DC motor to either the positive or negative output terminal of the rectifier DB1. This allows for forward and reverse rotation switching of the DC motor.
[0063] Continue to refer to Figure 1 Optionally, both the first relay RL1 and the second relay RL2 are relays equipped with single-pole double-throw switches, which not only provide flexible circuit switching functions, but also have many advantages such as high reliability, low power consumption, fast response, and easy control, which are conducive to improving the reliability of the control circuit.
[0064] Of course, it should be noted that in other embodiments of this disclosure, the first relay RL1 and the second relay RL2 may also be solid-state relays, relays equipped with double-pole double-throw switches, or other types of relays, which will not be described in detail here.
[0065] Specifically, when both the first relay RL1 and the second relay RL2 are relays equipped with a single-pole double-throw switch, the first relay RL1 includes one moving contact 1 and two stationary contacts 2 and 3. The moving contact 1 of the first relay RL1 is connected to the positive terminal of the DC motor. One of the stationary contacts 2 of the first relay RL1 is a second free terminal connected to the positive output terminal of the rectifier DB1, and the other stationary contact 3 is a first free terminal connected to the negative output terminal of the rectifier DB1. The two stationary contacts 2 and 3 of the first relay RL1 are connected to the positive output terminal and the negative output terminal of the rectifier DB1, respectively. The second relay RL2 includes one moving contact. The second relay RL2 has two stationary contacts 2 and 3. The moving contact 1 of the second relay RL2 is connected to the negative terminal of the DC motor. One of the stationary contacts 2 of the second relay RL2 is the first free terminal connected to the positive output terminal of the rectifier DB1, and the other stationary contact 3 is the second free terminal connected to the negative output terminal of the rectifier DB1. The two stationary contacts 2 and 3 of the second relay RL2 are connected to the positive output terminal and the negative output terminal of the rectifier DB1, respectively. A protective resistor R is provided between the positive output terminal of the rectifier DB1 and the stationary contact 2 of the second relay RL2, and between the negative output terminal of the rectifier DB1 and the stationary contact 3 of the first relay RL1.
[0066] The switching control circuit 10 includes a transistor TR1 and a transistor control circuit for controlling the operating state of the transistor TR1. The transistor TR1 is connected in series between the positive terminal of the power supply and the rectifier DB1, and the control terminal of the transistor TR1 is connected to the transistor control circuit. Optionally, the transistor TR1 includes a silicon controlled rectifier (SCR).
[0067] When the DC motor is not operating using the above technical solution, continue to refer to... Figure 1 At this time, the MCU signal RL1 is low, the transistor Q3 is not conducting, and the moving contact 1 and stationary contact 2 of the second relay RL2 are in contact; the MCU signal RL2 is low, the transistor Q2 is not conducting, and the moving contact 1 and stationary contact 2 of the first relay RL1 are in contact; the MCU signal TRIAC is low, the transistor Q1 is not conducting, the transistor TR1 is not conducting, the rectifier DB1 is not conducting, the circuit has no loop, and the DC motor does not work.
[0068] When the DC motor is rotating in the forward direction, continue to refer to... Figure 2 At this time, the MCU signal RL1 is high, the transistor Q3 is turned on, and the moving contact 1 and stationary contact 3 of the second relay RL2 are in contact; the MCU signal RL2 is low, the transistor Q2 is not turned on, and the moving contact 1 and stationary contact 2 of the first relay RL1 are in contact; the MCU signal TRIAC is high, the transistor Q1 is turned on, the transistor TR1 is turned on, the rectifier DB1 is turned on, the circuit forms a loop, and the DC motor starts to rotate forward.
[0069] When the DC motor is in reverse, continue to refer to... Figure 3 At this time, the MCU signal RL1 is low, the transistor Q3 is not conducting, and the moving contact 1 and stationary contact 2 of the second relay RL2 are in contact; the MCU signal RL2 is high, the transistor Q2 is conducting, and the moving contact 1 and stationary contact 3 of the first relay RL1 are in contact; the MCU signal TRIAC is high, the transistor Q1 is conducting, the transistor TR1 is conducting, the rectifier DB1 is conducting, the circuit forms a loop, and the DC motor starts to reverse.
[0070] By adopting the above technical solution, the DC motor can achieve forward and reverse rotation switching.
[0071] Among them, the first relay RL1 has weak shock resistance. When switching from reverse to forward rotation, and during forward rotation, if the food processor vibrates or is subjected to external interference, the free end of the single-pole double-throw switch of the first relay RL1 swings back and forth between the two stationary contacts, potentially causing arcing and generating surge current. This surge current may damage other components in the control circuit, causing damage to the food processor. For details, please refer to [link / reference]. Figure 4When the food processor is in the second state, that is, the DC motor is rotating in the forward direction, and the food processor vibrates or is disturbed by external forces, the moving contact 1 of the first relay RL1 will disconnect from the default contact and swing between the stationary contacts 2 and 3, causing an arc current. The surge current may damage other components in the control circuit and cause damage to the food processor.
[0072] Continue to refer to Figure 4 In some optional embodiments, the protection resistor R includes a second protection resistor 32 connected between the first free terminal of the first relay RL1 and the negative output terminal of the rectifier DB1. The second relay RL2 and the second protection resistor 32 are connected in series across the two ends of the DC motor, and both are connected to the second node N2, which is connected to the negative output terminal of the rectifier DB1. The second protection resistor 32 is located between the second node N2 and the first free terminal of the first relay RL1. That is, in the food processing machine provided by this disclosure, a second protection resistor 32 is provided between the negative output terminal of the rectifier DB1 and the stationary contact 3 of the first relay RL1. When the moving contact 1 of the first relay RL1 disconnects from the default contact and swings and arcs between the stationary contacts 2 and 3, causing a surge current, the second protection resistor 32 can absorb the surge current, preventing the surge current from damaging other components in the control circuit and causing damage to the food processing machine.
[0073] The second relay RL2 has weak shock resistance. During the switch from forward to reverse rotation, and during reverse rotation, if the food processor vibrates or is subjected to external interference, the free end of the single-pole double-throw switch of the second relay RL2 will continuously swing back and forth between the two stationary contacts, potentially causing arcing and generating surge current. This surge current may damage other components in the control circuit, causing damage to the food processor. For details, please refer to [link / reference]. Figure 5 When the food processor is in the third state, that is, the DC motor is in reverse, and the food processor vibrates or is disturbed by external forces, the moving contact 1 of the second relay RL2 will disconnect from the default contact and swing between the stationary contacts 2 and 3, causing an arc current. The surge current may damage other components in the control circuit and cause damage to the food processor.
[0074] Continue to refer to Figure 5In some optional embodiments, the protection resistor R includes a first protection resistor 31 connected between the first free terminal of the second relay RL2 and the positive output terminal of the rectifier DB1. The first relay RL1 and the first protection resistor 31 are connected in series across the two ends of the DC motor, and both are connected to the first node N1, which is connected to the positive output terminal of the rectifier DB1. That is, in the food processing machine provided by this disclosure, the first protection resistor 31 is connected between the positive output terminal of the rectifier DB1 and the stationary contact 2 of the second relay RL2. When the moving contact 1 of the second relay RL2 disconnects from the default contact and swings and arcs between the stationary contacts 2 and 3, causing a surge current, the first protection resistor 31 can absorb the surge current, preventing the surge current from damaging other components in the control circuit and causing damage to the food processing machine.
[0075] The above technical solution solves the technical problem that in existing food processing machines with forward and reverse rotation functions, relay sparking easily occurs during and after the forward and reverse rotation switching process under strong vibration.
[0076] It should be noted that the embodiments of this disclosure exemplarily illustrate one circuit structure of the control circuit. In other embodiments of this disclosure, the first relay control circuit, the second relay control circuit, and the transistor control circuit may also be configured with other circuit structures, which will not be described in detail here.
[0077] It should be noted that, in this document, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.
[0078] The above description is merely a specific embodiment of this disclosure, enabling those skilled in the art to understand or implement it. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of this disclosure. Therefore, this disclosure is not to be limited to the embodiments described herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.
Claims
1. A food processing machine, comprising: A DC motor and a control circuit for controlling the forward and reverse operation of the DC motor, characterized in that the control circuit includes a rectifier and a first relay and a second relay that work together to control the forward and reverse operation of the DC motor; The first relay includes a first free terminal connected to the negative output terminal of the rectifier and a second free terminal connected to the positive output terminal of the rectifier. Either the first free terminal or the second free terminal of the first relay is connected to the positive terminal of the DC motor. The second relay includes a first free terminal connected to the positive output terminal of the rectifier and a second free terminal connected to the negative output terminal of the rectifier. Either the first free terminal or the second free terminal of the second relay is connected to the negative terminal of the DC motor. Protective resistors are provided between the first free terminal of the first relay and the negative output terminal of the rectifier, and between the first free terminal of the second relay and the positive output terminal of the rectifier.
2. The food processing machine according to claim 1, characterized in that, The food processing machine is configured such that the current passing through the protective resistor during operation is greater than or equal to 22A, and the protective resistor is a positive temperature coefficient thermistor.
3. The food processing machine according to claim 1, characterized in that, The food processing machine is configured such that the current passing through the protective resistor during operation is less than 22A, and the protective resistor is a negative temperature coefficient thermistor.
4. The food processing machine according to claim 1, characterized in that, Both the first relay and the second relay are relays equipped with a single-pole double-throw switch.
5. The food processing machine according to claim 4, characterized in that, The first relay includes a moving contact and two stationary contacts. The moving contact of the first relay is connected to the positive terminal of the DC motor. One of the stationary contacts of the first relay is a second free terminal connected to the positive output terminal of the rectifier, and the other stationary contact is a first free terminal connected to the negative output terminal of the rectifier. The second relay includes a moving contact and two stationary contacts. The moving contact of the second relay is connected to the negative terminal of the DC motor. One of the stationary contacts of the second relay is a first free terminal connected to the positive output terminal of the rectifier, and the other stationary contact is a second free terminal connected to the negative output terminal of the rectifier.
6. The food processing machine according to claim 1, characterized in that, The protective resistor includes a first protective resistor connected between the first free end of the second relay and the positive output terminal of the rectifier. The first relay and the first protective resistor are respectively connected in series at both ends of the DC motor, and the two intersect to form a first node. The first node is connected to the positive output terminal of the rectifier.
7. The food processing machine according to claim 6, characterized in that, The first protective resistor is located between the first node and the first free end of the second relay.
8. The food processing machine according to claim 1, characterized in that, The protection resistor includes a second protection resistor connected between the first free terminal of the first relay and the negative output terminal of the rectifier. The second relay and the second protection resistor are respectively connected in series at both ends of the DC motor, and the two intersect to form a second node. The second node is connected to the negative output terminal of the rectifier.
9. The food processing machine according to claim 8, characterized in that, The second protection resistor is located between the second node and the first free end of the first relay.
10. The food processing machine according to claim 1, characterized in that, The protective resistor is set as a positive temperature coefficient thermistor with a resistance between 2-3Ω at room temperature; or... The protective resistor is set as a negative temperature coefficient thermistor with a resistance of 10-20Ω at room temperature.