Circuit for eliminating electric spark generated by relay contact in working process

Abstract

The utility model discloses a circuit for eliminating electric sparks generated by relay contacts during working, belongs to the circuit control technology, and aims to solve the problem that the service life of a product is seriously influenced due to the fact that the existing circuit using a relay to control a load to work forwards or backwards generates the sparks when the contacts of the relay are closed or released. According to the utility model, the relay and the switch tube are connected in series in the load power supply loop; when a load is started, the relay is actuated firstly, and then the switch tube is turned on; when the load is stopped, the switching tube is firstly closed, and then the relay is released. Therefore, when the relay is closed and released, the switching tube is not connected with a loop, no current passes through the contact of the relay during action, and no electric spark is generated. The rated on-load 100,000-time electrical service life of the relay reaches 1,000,000-time mechanical service life, and the enabling service life of the relay is greatly prolonged.

Description

Technical Field

[0001] This utility model belongs to circuit control technology, specifically relating to a circuit that eliminates electrical sparks generated by relay contacts during operation. Background Technology

[0002] Circuits that use relays to control motors or similar loads to operate in the forward or reverse direction can generate sparks when the relay contacts engage or disengage, severely impacting the product's lifespan. Utility Model Content

[0003] The technical problem to be solved and the technical task proposed by this utility model is to overcome the defect that existing circuits using relays to control the forward or reverse operation of loads generate sparks when the relay contacts are engaged or disengaged, which seriously affects the service life of the product. The present invention provides a circuit that eliminates the electrical sparks generated by the relay contacts during operation, thereby improving the enable life of the relay.

[0004] To achieve the above objectives, the present invention provides a circuit for eliminating electrical sparks generated by relay contacts during operation, comprising a relay connected in series in the load power supply circuit, and a switching transistor connected in series in the load power supply circuit to control the on / off state of the entire load power supply circuit.

[0005] Therefore, when starting the load, the relay is energized first, and then the switching transistor is turned on; when stopping the load, the switching transistor is turned off first, and then the relay is released. The switching transistor can be a controllable device with a circuit that can connect or disconnect, such as a MOSFET or a switching transistor.

[0006] When a relay is under rated load, its electrical life is generally 100,000 cycles, and its mechanical life is generally 1 million cycles. By adding a switching transistor, the relay can be made to operate without generating electric sparks during activation and deactivation (because the switching transistor does not connect the circuit during activation and deactivation, and no current flows through the relay contacts, thus preventing electric sparks). This directly extends the electrical life of the relay to the level of its mechanical life, greatly improving the relay's enable life.

[0007] In one embodiment: the load is one; the relay includes a first relay and a second relay for changing the direction of the current in the load power supply circuit, the first relay and the second relay being connected in series in the load power supply circuit and configured to change the direction of the current in the load power supply circuit by switching their operating states.

[0008] Preferably, both the first relay and the second relay have a first pin, a second pin, and a third pin. The first pin of each relay is connected to the load power supply circuit. As the relay changes its energized and de-energized state, its second pin or third pin is selectively connected to its first pin to connect to the load power supply circuit.

[0009] In another embodiment: the load includes a first load and a second load; the relay includes a first relay and a second relay for changing the current direction of the load power supply circuit and a third relay for selectively switching the first load and the second load to the load power supply circuit, the first relay and the second relay being connected in series in the load power supply circuit and configured to change the current direction of the load power supply circuit by switching their operating states, and the third relay being connected in series in the load power supply circuit and configured to selectively switch the first load and the second load to the load power supply circuit by switching its operating states.

[0010] Preferably, the first relay, the second relay, and the third relay each have a first pin, a second pin, and a third pin. The first pin of each relay is connected to the load power supply circuit. As the relay changes its energized and de-energized state, its second pin or third pin is selectively connected to its first pin to connect to the load power supply circuit.

[0011] Optionally, each relay can be either a normally open relay or a normally closed relay.

[0012] Preferably, the switching transistor is connected in series at the end of the current flow direction of the load power supply circuit.

[0013] Preferably, the load power supply circuit is connected to a diode, which absorbs the reverse induced electromotive force generated by the internal coil of the load when the load stops.

[0014] Preferably, the anode of the diode is connected to the front end of the switching transistor, and the cathode of the diode is connected to the load power supply, according to the direction of the current during load operation. This ensures that when the switching transistor disconnects the load power supply circuit, regardless of the direction of the load current, the diode can always establish a reverse induced electromotive force absorption circuit to absorb the reverse induced electromotive force generated by the internal coil of the load.

[0015] The method for eliminating electrical sparks generated by relay contacts during operation, as described in this invention, involves connecting a relay and a switching transistor in series in the load power supply circuit. When starting the load, the relay is first energized, and then the switching transistor is turned on. When stopping the load, the switching transistor is first turned off, and then the relay is released. Therefore, when the relay is energized and released, the switching transistor does not connect the circuit, and no current flows through the relay contacts during operation, thus preventing the generation of electrical sparks.

[0016] When a relay is under rated load, its electrical life is generally 100,000 cycles, and its mechanical life is generally 1 million cycles. By adding a switching transistor, the relay can be made to operate without generating electrical sparks during engagement and disengagement, thus extending its electrical life to the same level as its mechanical life and greatly improving its enable life. Attached Figure Description

[0017] Figure 1 This is a circuit diagram of Embodiment 1 of the present invention;

[0018] Figure 2 This is a schematic diagram showing that the load power supply circuit of Embodiment 1 of this utility model has been switched to a certain current direction;

[0019] Figure 3 This is a schematic diagram showing that the load power supply circuit of Embodiment 1 of this utility model has been switched to another current direction;

[0020] Figure 4 This is a circuit diagram of Embodiment 2 of the present invention;

[0021] Figure 5 This is a schematic diagram of Embodiment 2 of the present invention, showing how the first load is switched to the load power supply circuit and operates according to a current direction;

[0022] Figure 6 This is a schematic diagram of Embodiment 2 of the present invention, in which the first load is switched to the load power supply circuit and operates according to another current direction;

[0023] Figure 7 This is a schematic diagram of Embodiment 2 of the present invention, showing how the second load is switched to the load power supply circuit and operates according to a current direction;

[0024] Figure 8 This is a schematic diagram of Embodiment 2 of the present invention, in which the second load is switched to the load power supply circuit and operates according to another current direction;

[0025] Explanation of the labels in the diagram:

[0026] 100 load, 110 first load, 120 second load;

[0027] 210 First relay, 211 First pin, 212 Second pin, 212 Third pin;

[0028] 220 Second relay, 221 First pin, 222 Second pin, 223 Third pin;

[0029] 230 Third relay, 231 First pin, 232 Second pin, 233 Third pin;

[0030] 300 switching transistor;

[0031] 400 diode. Detailed Implementation

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

[0033] The terms “comprising” and “having”, and any variations thereof, in the specification and claims of this utility model are intended to cover non-exclusive inclusion, such as a method or product that includes a series of technical features, not limited to those technical features explicitly listed, but also including other technical features that may be included in the method or product but not explicitly listed.

[0034] In the description of this utility model, it should be understood that the technical features defined by terms such as "first" and "second" which have a sequential concept are only for the purpose of clearly describing the defined technical features and making the defined technical features clearly distinguishable from other technical features, and do not represent that they are named in this way in actual implementation. Therefore, they should not be construed as limitations on this utility model.

[0035] The present invention will now be described in detail with reference to specific embodiments and accompanying drawings.

[0036] Example 1

[0037] like Figure 1-3 The circuit shown eliminates electrical sparks generated by relay contacts during operation. The load 100 is a single unit. A first relay 210, a second relay 220, and a switching transistor 300 are connected in series in the load power supply circuit. The first relay 210 and the second relay 220 are configured to change the current direction in the load power supply circuit by switching their operating states. The switching transistor 300 controls the on / off state of the entire load power supply circuit. In this embodiment, the switching transistor 300 is a switching transistor. In other embodiments, the switching transistor can be replaced by a controllable device with an on / off circuit, such as a MOSFET.

[0038] Specifically, the first relay 210 has a first pin 211, a second pin 212, and a third pin 213, and the second relay 220 has a first pin 221, a second pin 222, and a third pin 223. The first pin of each relay is connected to the load power supply circuit. As the relay changes its energized and de-energized state, its second pin or third pin is selectively connected to its first pin to connect to the load power supply circuit.

[0039] In the diagram, the switching transistor 300 is connected in series at the end of the current flow direction of the load power supply circuit.

[0040] In this embodiment, each relay is a normally open relay. When the first relay 210 is in the default state, pins 211 and 212 are connected, and pins 211 and 212 are disconnected; when the first relay 210 is in the energized state, pins 211 and 212 are connected, and pins 211 and 212 are disconnected. When the second relay 220 is in the default state, pins 221 and 222 are connected, and pins 221 and 223 are disconnected; when the second relay 220 is in the energized state, pins 221 and 223 are connected, and pins 221 and 222 are disconnected. Since relays switch circuits by their activation and deactivation, in other embodiments, normally closed relays can be used to connect to the circuit and their wiring and control methods can be changed to replace normally open relays.

[0041] Figure 1-3 In the diagram, VCC is the power supply for the load, VDD is the power supply for the relay, GND is ground, R is a resistor, + is the positive terminal of the power supply for the load, - is the negative terminal of the power supply for the load, S, D, and G are the three pins of the switching transistor, and PRY controls the corresponding relay to engage and disengage.

[0042] like Figure 2 As shown, to start load 100, first set the first relay 210 to its default state (normally open) and the second relay 220 to its energized state. Then turn on the switch 300, and the load power supply circuit is connected. The load operating current direction is negative (-) on the left and positive (+) on the right. To stop the load, first turn off the switch 300, then set the first relay 210 to its default state (normally open) and the second relay 220 to its default state (normally open). The load power supply circuit is then disconnected by the second relay, and load 100 stops working. Figure 2 In the diagram, a single-dot dash indicates a connected load power supply circuit.

[0043] like Figure 3 As shown, to start load 100, first turn the first relay 210 into the energized state and the second relay 220 into the default state (normally open state), then turn on the switch 300. The load power supply circuit is then connected, and the load operating current direction is positive (+) on the left and negative (-) on the right. To stop the load, first turn off the switch 300, then turn the first relay 210 into the default state (normally open state) and the second relay 220 into the default state (normally open state). The load power supply circuit is then disconnected by the first relay, and load 100 stops working. Figure 3 In the diagram, a single-dot dash indicates a connected load power supply circuit.

[0044] As mentioned above, Figure 2 The direction of the operating current of medium load 100 is the same as Figure 3The operating current of a medium load of 100 is in the opposite direction.

[0045] Therefore, by switching the engaging and disengaging states of the first relay 210 and the second relay 220, the current direction of the load power supply circuit can be changed, causing the load 100 to work in reverse (such as changing the direction of the motor).

[0046] As mentioned earlier, when the relay is engaged and disengaged, the switching transistor does not connect the circuit, and no current flows through the relay contacts during operation, thus preventing the generation of electrical sparks and extending the relay's enable life.

[0047] Furthermore, when the switch 300 is turned off to stop the load, a reverse induced electromotive force (EMF) will be generated in the internal coil of the load 100. This reverse induced EMF is detrimental to the switch 300. To eliminate this disadvantage, a diode 400 is connected to the load power supply circuit. Specifically, the positive terminal of the diode 400 is connected between the second relay 220 and the switch 300, and the negative terminal of the diode 400 is connected to the load power supply. When the switch 300 is turned off to stop the load, regardless of the direction of the load current, the diode can always establish a reverse induced EMF absorption circuit to absorb the reverse induced EMF generated by the internal coil of the load. Therefore, the connection position of the diode should be suitable for changing the direction of the load current while also establishing a reverse induced EMF absorption circuit. According to the current direction when the load is operating, it is advisable to connect the positive terminal of the diode 400 to the front end of the switch 300.

[0048] Example 2

[0049] like Figure 4-8 The circuit shown eliminates electrical sparks generated by relay contacts during operation. It includes a first load 110 and a second load 120. The relays include a first relay 210 and a second relay 220 for changing the current direction in the load power supply circuit, and a third relay 230 for selectively switching the first load 110 and the second load 120 into the load power supply circuit. The first relay 210 and the second relay 220 are connected in series in the load power supply circuit and configured to change the current direction in the load power supply circuit by switching their operating states. The third relay 230 is connected in series in the load power supply circuit and configured to selectively switch the first load 110 and the second load 120 into the load power supply circuit by switching its operating states. A switching transistor 300 is connected in series in the load power supply circuit to control the on / off state of the entire load power supply circuit. In this embodiment, the switching transistor 300 is a switching transistor. In other embodiments, the switching transistor can be replaced by a controllable device with an on / off circuit, such as a MOSFET.

[0050] Specifically, the first relay 210 has a first pin 211, a second pin 212, and a third pin 213; the second relay has a first pin 221, a second pin 222, and a third pin 223; and the third relay 230 also has a first pin 231, a second pin 232, and a third pin 233. The first pin of each relay is connected to the load power supply circuit. As each relay changes its energized and de-energized state, its second and third pins are selectively connected to its first pin to connect to the load power supply circuit.

[0051] In the diagram, the switching transistor 300 is connected in series at the end of the current flow direction of the load power supply circuit.

[0052] In this embodiment, each relay is a normally open relay. When the first relay 210 is in its default state, pins 211 and 212 are connected, and pins 211 and 212 are disconnected; when the first relay 210 is in its energized state, pins 211 and 212 are connected, and pins 211 and 212 are disconnected. When the second relay 220 is in its default state, pins 221 and 222 are connected, and pins 221 and 223 are disconnected; when the second relay 220 is in its energized state, pins 221 and 223 are connected, and pins 221 and 222 are disconnected. When the third relay 230 is in its default state, pins 231 and 232 are connected, and pins 231 and 232 are disconnected; when the third relay 230 is in its energized state, pins 231 and 232 are connected, and pins 231 and 232 are disconnected.

[0053] Since relays switch circuits by engaging and disengaging, in other embodiments, normally closed relays can be used to replace normally open relays by connecting them to the circuit and changing their wiring and control methods.

[0054] Figure 4-8 In the diagram, VCC is the power supply for the load, VDD is the power supply for the relay, GND is ground, R is a resistor, + is the positive terminal of the power supply for the load, - is the negative terminal of the power supply for the load, S, D, and G are the three pins of the switching transistor, and PRY controls the corresponding relay to engage and disengage.

[0055] like Figure 5-6 As shown, the third relay 230 is in the energized state, the first load 110 is switched into the load power supply circuit, and the second load 120 is switched out of the load power supply circuit.

[0056] like Figure 5As shown, to start the first load 110, first set the first relay 210 to its default state (normally open) and the second relay 220 to its energized state. Then turn on the switch 300, and the load power supply circuit is connected. The load operating current direction is negative (-) at the top and positive (+) at the bottom. To stop the first load 110, first turn off the switch 300, then set the first relay 210 to its default state (normally open) and the second relay 220 to their default state (normally open). The load power supply circuit is then disconnected by the second relay 220, and the first load 110 stops working. Figure 5 In the diagram, a single-dot dash indicates a connected load power supply circuit.

[0057] like Figure 6 As shown, to start the first load 110, first turn the first relay 210 into the energized state and the second relay 220 into the default state (normally open state), then turn on the switch 300. The load power supply circuit is then connected, and the load operating current direction is positive (+) at the top and negative (-) at the bottom. To stop the first load 110, first turn off the switch 300, then turn the first relay 210 into the default state (normally open state) and the second relay 220 into the default state (normally open state). The load power supply circuit is then disconnected by the first relay 210, and the first load 110 stops working. Figure 6 In the diagram, a single-dot dash indicates a connected load power supply circuit.

[0058] As mentioned above, Figure 5 The direction of the operating current of the first load 110 is the same as Figure 6 The operating current of the first load 110 is in the opposite direction.

[0059] like Figure 7-8 As shown, the third relay 230 is in the default state (normally open state), the second load 120 is switched to the load power supply circuit, and the first load 110 is switched out of the load power supply circuit.

[0060] like Figure 7 As shown, to start the second load 120, first set the first relay 210 to its default state (normally open) and the second relay 220 to its energized state. Then turn on the switch 300, and the load power supply circuit is connected. The operating current of the second load 120 is negative at the top and positive at the bottom. To stop the second load 120, first turn off the switch 300, then set the first relay 210 to its default state (normally open) and the second relay 220 to its default state (normally open). The load power supply circuit is then disconnected by the second relay 220, and the second load 120 stops working. Figure 7 In the diagram, a single-dot dash indicates a connected load power supply circuit.

[0061] like Figure 8As shown, to start the second load 120, first turn the first relay 210 into the energized state and the second relay 220 into the default state (normally open state), then turn on the switch 300. The load power supply circuit is then connected, and the operating current of the second load 120 is positive (+) at the top and negative (-) at the bottom. To stop the second load 120, first turn off the switch 300, then turn the first relay 210 and the second relay 220 into the default state (normally open state). The load power supply circuit is then disconnected by the first relay 210, and the second load 120 stops working. Figure 8 In the diagram, a single-dot dash indicates a connected load power supply circuit.

[0062] As mentioned above, Figure 7 The direction of the operating current of the second load 120 is the same as Figure 8 The operating current of the second load 120 is in the opposite direction.

[0063] Therefore, by switching the activation and deactivation states of the third relay, the first and second loads can be selectively switched to the load power supply circuit. By switching the activation and deactivation states of the first and second relays, the current direction in the load power supply circuit can be changed, causing the load to operate in reverse (such as changing the direction of a motor).

[0064] As mentioned earlier, when the relay is engaged and disengaged, the switching transistor does not connect the circuit, and no current flows through the relay contacts during operation, thus preventing the generation of electrical sparks and extending the relay's enable life.

[0065] In this embodiment, when the switch 300 is turned off to stop the first or second load, both the first and second loads will generate a reverse induced electromotive force (EMF) in their internal coils. This reverse EMF is detrimental to the switch 300. To eliminate this disadvantage, a diode 400 is connected to the load power supply circuit. Specifically, the anode of the diode 400 is connected between the second relay 220 and the switch, and the cathode of the diode 400 is connected to the load power supply. When the switch 300 is turned off to stop the first or second load, regardless of the direction of the operating current of the first or second load, the diode can always establish a reverse induced EMF absorption circuit to absorb the reverse induced EMF generated by the internal coils of the first or second load. Therefore, the diode's connection position should be suitable for changing the direction of the operating current of the first and second loads while also establishing a reverse induced EMF absorption circuit. It is preferable that the anode of the diode 400 is connected to the front end of the switch 300, according to the current direction when the first and second loads are operating.

Claims

1. A circuit that eliminates electrical sparks generated by relay contacts during operation, including relays connected in series in the load power supply circuit, characterized in that: The load power supply circuit also has a switch (300) connected in series to control the on / off state of the entire load power supply circuit.

2. The circuit according to claim 1, characterized in that: The load (100) is one; the relays include a first relay (210) and a second relay (220) for changing the direction of the current in the load power supply circuit, the first relay and the second relay being connected in series in the load power supply circuit and configured to change the direction of the current in the load power supply circuit by switching their operating states.

3. The circuit according to claim 2, characterized in that: The first relay (210) and the second relay (220) each have a first pin, a second pin, and a third pin. The first pin of each relay is connected to the load power supply circuit. As the relay changes its state of being engaged and disengaged, its second pin and third pin are selectively connected to its first pin to connect to the load power supply circuit.

4. The circuit according to claim 1, characterized in that: The load includes a first load (110) and a second load (120); the relay includes a first relay (210) and a second relay (220) for changing the current direction of the load power supply circuit and a third relay (230) for selectively switching the first load and the second load to the load power supply circuit. The first and second relays are connected in series in the load power supply circuit and configured to change the current direction of the load power supply circuit by switching their operating states. The third relay is connected in series in the load power supply circuit and configured to selectively switch the first load and the second load to the load power supply circuit by switching its operating states.

5. The circuit according to claim 4, characterized in that: The first relay (210), the second relay (220) and the third relay (230) each have a first pin, a second pin and a third pin. The first pin of each relay is connected to the load power supply circuit. As the relay changes its state of being engaged and disengaged, its second pin and third pin are selectively connected to its first pin to be connected to the load power supply circuit.

6. The circuit according to any one of claims 1-5, characterized in that: Each relay is either a normally open relay or a normally closed relay.

7. The circuit according to any one of claims 1-5, characterized in that: The switching transistor is connected in series at the end of the current flow path in the load power supply circuit.

8. The circuit according to any one of claims 1-5, characterized in that: A diode (400) is connected to the load power supply circuit. When the load stops, the diode (400) absorbs the reverse induced electromotive force generated by the coil inside the load.

9. The circuit according to claim 8, characterized in that: According to the current direction when the load is working, the positive terminal of the diode (400) is connected to the front end of the switching transistor (300), and the negative terminal of the diode (400) is connected to the load power supply.

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