Automatic control system for lubricating oil furnace

Abstract

The utility model discloses a specific automatic control system of lubricating oil furnace, including control portion, executive portion and sensing portion, control portion includes the control man -machine interface of lubricating oil furnace, programmable controller PLC, switch power supply, PLC includes input, output, control portion passes through PLC, receives all from the control man -machine interface of lubricating oil furnace instruction and the input terminal signal of PLC, sends control command to the output of PLC after logic judgement, the output of executive portion is connected in the PLC through communication cable, is responsible for according to the control command of control portion, drives the execution element in lubricating oil furnace through a series of intermediate relay, sensing portion is connected in the input of PLC through communication cable, is responsible for the sensor signal feedback of each lubricating oil furnace to PLC, the utility model discloses can remote operation, is favorable to operator's physical health, and can keep the oil temperature of lubricating oil always satisfy hydrogen removal requirement strictly.

Description

Technical Field

[0001] This utility model relates to the field of hydrogen removal and automatic control of lubricating oil furnaces, specifically an automatic control system for lubricating oil furnaces. Background Technology

[0002] High-load, high-precision parts such as aircraft landing gear, engine bearings, and precision gears are generally made of high-strength metals, such as high-strength steel and titanium alloys. During the smelting, electroplating, pickling, and welding processes, these metals absorb hydrogen atoms. These tiny hydrogen atoms penetrate the metal's interior and accumulate in the crystal lattice, causing delayed brittle fracture under stress below their yield strength. For aircraft landing gear, engine bearings, and precision gears, this fracture is almost entirely undetectable and extremely dangerous; therefore, hydrogen removal is essential.

[0003] Currently, the main method used is to heat and remove hydrogen from high-load, high-precision aircraft parts using a mature and widely applied lubricating oil furnace. The working principle is as follows: precision parts that have absorbed hydrogen atoms are placed in the lubricating oil furnace, which uses aviation lubricating oil as the medium. The parts are heated to a set temperature and held at that temperature for a set time, allowing the hydrogen atoms to gain sufficient energy to diffuse and escape from the metal, thus achieving hydrogen removal. However, the existing technology has the following problems: First, the hydrogen removal process requires strict control of the oil temperature, necessitating constant close monitoring by operators. However, the evaporation of aviation lubricating oil upon heating produces an unpleasant odor, which is detrimental to the health of the operators. Second, the oil temperature is controlled by a simple temperature controller, which, if not properly managed, can easily exceed the upper temperature limit, potentially leading to combustion and explosion safety issues. Summary of the Invention

[0004] To overcome the shortcomings of existing technologies, this utility model provides an automatic control system for a lubricating oil furnace. Based on a programmable control chip, a human-machine interface, a switching power supply, and a series of sensors and switches, the automatic control system for the lubricating oil furnace can remotely and automatically perform hydrogen removal operations on aerospace parts, which is beneficial to the health of operators and can strictly maintain the oil temperature of the lubricating oil to meet the hydrogen removal requirements, avoiding situations where the temperature exceeds the upper limit.

[0005] The technical solution of this utility model is:

[0006] The automatic control system for the lubricating oil furnace includes a control unit, an execution unit, and a sensing unit;

[0007] The control unit includes a human-machine interface (HMI) for the lubricating oil furnace, a programmable logic controller (PLC), and a switching power supply (SMPS). The PLC includes input terminals and output terminals. The switching power supply converts 220V AC power to 24V DC power to supply power to the HMI and the PLC output terminals of the lubricating oil furnace. The HMI is connected to the PLC via a communication cable and displays the status parameters of the lubricating oil furnace's automatic control system, providing an interface for manual input of commands. The control unit receives all commands from the HMI and input signals from the PLC, and after logical judgment, sends control commands to the PLC's output terminals.

[0008] The actuator is connected to the output of the programmable logic controller (PLC) in the control unit via a communication cable. It is responsible for driving the actuators in the lubricating oil furnace by activating a series of intermediate relays according to the control commands from the control unit. The actuator includes a first intermediate relay KA1, a second intermediate relay KA2, a third intermediate relay KA3, a fourth intermediate relay KA4, a fifth intermediate relay KA5, a red indicator light, a yellow indicator light, a green indicator light, and a buzzer. The actuators in the lubricating oil furnace include the exhaust fan motor and the first heater R1 and the second heater R2 for heating the lubricating oil.

[0009] The sensing unit is connected to the input terminal of the programmable logic controller (PLC) in the control unit via a communication cable, and is responsible for feeding back a series of sensor signals from the lubricating oil furnace to the PLC in the control unit. The sensing unit includes a first oil temperature controller, a second temperature controller, a third temperature controller, an upper oil level sensor, a high oil level sensor, a middle-high oil level sensor, a low oil level sensor, a fan thermal relay feedback terminal, a timer, and an optical grating.

[0010] Furthermore, the control unit also includes a cabinet and installed inside the cabinet are a first circuit breaker QF1, a second circuit breaker QF2, a first contactor KM1, a second contactor KM2, a third contactor KM3, a first solid-state relay SSR1, a second solid-state relay SSR2, a thermal relay FR1, a first fuse FU1, a second fuse FU2, a first current transformer, and a second current transformer.

[0011] The human-machine interface for controlling the lubricating oil furnace is located on the cabinet panel. The first, second, and third temperature controllers are also located on the cabinet panel, while the PLC and switching power supply are located inside the cabinet.

[0012] The first circuit breaker QF1 is a 4-pole switch, and the second circuit breaker QF2 is a 1-pole switch. After the cabinet is connected to 380V AC power through the first circuit breaker QF1, it is divided into three main control circuits. The first main control circuit supplies power to the fan motor after being protected by the first circuit breaker QF1, contactor KM1, and thermal relay FR1. The second main control circuit supplies power to the first heater R1 after being protected by the first circuit breaker QF1, first solid-state relay SSR1, first fuse FU1, and first current transformer. The third main control circuit supplies power to the second heater R2 after being protected by the first circuit breaker QF1, second solid-state relay SSR2, second fuse FU2, and second current transformer.

[0013] The first intermediate relay KA1 is connected to contactor KM1, the second intermediate relay KA2 is connected to the first solid-state relay SSR1, the third intermediate relay KA3 is connected to the first solid-state relay SSR2, the fourth intermediate relay KA4 is connected to the second contactor KM2, and the fifth intermediate relay KA5 is connected to the third contactor KM3 to form a secondary control circuit.

[0014] The second circuit breaker is connected to one of the live wires of the power supply connected to the first circuit breaker. The second circuit breaker supplies power to the secondary control circuit, PLC, and switching power supply in sequence. The switching power supply has a built-in rectifier circuit to convert 220V AC to 24V DC. The output port of the switching power supply is connected to the control human-machine interface of the lubricating oil furnace and the output terminal of the PLC, providing power to the components of the control human-machine interface and the actuator of the PLC output terminal of the lubricating oil furnace.

[0015] Below the human-machine interface on the cabinet panel is an operation panel, which includes an automatic / manual switch button, a start button, a stop button, a reset button, and an emergency stop button. These buttons are connected to the input terminals of the PLC in the control unit via communication cables. The automatic / manual switch button is used to switch control modes, the start button is used to start automatic operation, the stop button is used to stop the system, the reset button is used to unlock the program and return the system to its initial state after an abnormality is resolved, and the emergency stop button is used for emergency stop.

[0016] Furthermore, the control unit also includes a remote controller, which is connected to the input terminal of the control unit PLC. The remote controller is equipped with the same automatic / manual switching button, start button, stop button, reset button, and emergency stop button as the operation panel, and can remotely control the same functions as the control panel buttons.

[0017] Furthermore, in the secondary control circuit, the first intermediate relay KA1 is connected to the contactor KM1 to control the on and off of the power supply path of the fan motor; the second intermediate relay KA2 is connected to the first solid-state relay SSR1 to control the on and off of the power supply path of the first heater R1; the third intermediate relay KA3 is connected to the second solid-state relay SSR2 to control the on and off of the power supply path of the second heater R2; the fourth intermediate relay KA4 is connected to the second contactor KM2 to control the on and off of the power supply of the three temperature controllers; and the fifth intermediate relay KA5 is connected to the third contactor KM3 to control the on and off of the power supply path of the timer in the sensing unit.

[0018] Furthermore, the specific control of the association between the actuator and the sensor and the lubricating oil furnace is as follows:

[0019] The lubricating oil furnace includes an oil tank, a first heater R1, a second heater R2, a first thermocouple, a second thermocouple, a third thermocouple, two level gauges, an oil dipstick, and an oil extraction fan;

[0020] The oil tank contains lubricating oil; a grating is installed at the opening of the oil tank to detect whether there are people or foreign objects at the opening, serving as a start-up condition; each of the two level gauges has upper and lower floats, and each float has a level sensor, meaning the four floats are respectively equipped with an upper oil level sensor, a high oil level sensor, a mid-high oil level sensor, and a low oil level sensor to measure the lubricating oil level, and the PLC sends the lubricating oil level data to the human-machine interface of the lubricating oil furnace for real-time display; the dipstick is used for visual inspection to check whether the oil level meets the requirements.

[0021] The oil extraction fan is driven by a fan motor and is used to extract lubricating oil vapor and purify the air. The fan motor in the oil extraction fan is powered by the first main control circuit and its on / off state is controlled by the PLC through the first intermediate relay KA1 of the actuator. The feedback terminal of the first thermal relay FR1 is connected to the input terminal of the PLC of the control unit to detect whether the fan motor is overloaded and to provide the PLC with a fan motor overload protection signal. If the fan motor is overloaded, the equipment stops, the red indicator light flashes, the buzzer sounds an alarm, and the human-machine interface prompts that the fan motor is overloaded.

[0022] The first heater R1 and the second heater R2 are located at both ends of the oil tank and are used to heat the lubricating oil in the oil tank to a set temperature. The first heater R1 is powered by the second main control circuit and is controlled by the PLC through the second intermediate relay KA2 of the actuator. The second heater R2 is powered by the third main control circuit and is controlled by the PLC through the third intermediate relay KA3 of the actuator.

[0023] A first thermocouple, a second thermocouple, and a third thermocouple are positioned at three different locations in the oil tank to measure the oil temperature at different points. The first thermocouple is connected to a first temperature controller to control the oil temperature. The second thermocouple is connected to a second temperature controller to control the fan motor. The third thermocouple is connected to a third temperature controller and measures only the temperature, serving as a reference for the first and second thermocouples. The PLC sends the oil temperatures collected by the three temperature controllers to the human-machine interface of the lubricating oil furnace for real-time display.

[0024] The first temperature controller, based on the lubricating oil temperature measured by the first thermocouple, outputs a heating signal to the PLC if the lubricating oil temperature is lower than the set value for dehydrogenation. The PLC then activates the coils of the second and third intermediate relays KA2 and KA3, which in turn activate SSR1 and SSR2. SSR1 and SSR2 conduct the heating circuit, and the first heater R1 and the second heater R2 heat the oil, raising its temperature. When the temperature reaches the set value for dehydrogenation, the first temperature controller disconnects the heating request signal to the PLC. The PLC then disconnects the coils of the second and third intermediate relays KA2 and KA3, stopping the heating and ensuring that the lubricating oil remains at the set dehydrogenation temperature during the dehydrogenation process. Furthermore, when the lubricating oil temperature reaches the set dehydrogenation temperature, the PLC activates the coil of the fourth intermediate relay KA4, which in turn activates the coil of the second contactor KM2. The contactor engages, and the timer starts counting. The PLC sends the timer's time to the control human-machine interface of the lubricating oil furnace for real-time display. When the timer reaches the set dehydrogenation time, the PLC controls the buzzer to sound an alarm, and the yellow indicator light illuminates.

[0025] The second temperature controller, based on the lubricating oil temperature measured by the second thermocouple, outputs a smoke extraction and exhaust signal to the PLC if the lubricating oil temperature is higher than the set value for lubricating oil exhaust temperature. The PLC then activates the coil of the first intermediate relay KA1, which in turn activates the coil of the first contactor KM1. The contactor engages, and the fan motor starts to perform smoke extraction and exhaust. If the lubricating oil temperature is lower than the set value for lubricating oil exhaust temperature, the second temperature controller disconnects the smoke extraction and exhaust signal from the PLC. The PLC then disconnects the coil of the first intermediate relay KA1, and the fan motor stops performing smoke extraction and exhaust.

[0026] Furthermore, when using the above-mentioned automatic control system for lubricating oil furnaces for automated operation, the specific steps are as follows:

[0027] Step 1: Start-up preparation;

[0028] Immerse the parts to be dehydrogenated in the lubricating oil, set the dehydrogenation temperature, dehydrogenation time, and lubricating oil exhaust temperature. The automatic control system of the lubricating oil furnace defaults to the automatic / manual switch. The operator presses the start button on the remote control, the PLC activates the KA4 coil, the normally open contact of KA4 is closed, the temperature controller is powered on, and the equipment enters self-test mode. That is, the PLC checks whether the conditions of each input port meet the normal start-up and operation conditions, including the lubricating oil level is within the allowable range, there are no people or foreign objects in the tank opening, the thermal relay is normal, and the initial temperature of the lubricating oil is within the normal range. If the conditions are met, proceed to the next step.

[0029] Step 2: Heat the lubricating oil to the set dehydrogenation temperature and maintain it at that temperature;

[0030] The first temperature controller, based on the lubricating oil temperature, outputs a heating signal to the PLC if the lubricating oil temperature is lower than the set value for dehydrogenation. The PLC then activates the coils of the second intermediate relay KA2 and the third intermediate relay KA3, which in turn activates SSR1 and SSR2. SSR1 and SSR2 conduct the heating circuit, and the first heater R1 and the second heater R2 heat the oil, raising its temperature. When the temperature reaches the set value for dehydrogenation, the first temperature controller disconnects the heating request signal to the PLC. The PLC then disconnects the coils of the second intermediate relay KA2 and the third intermediate relay KA3, stopping the heating and ensuring that the lubricating oil remains at the set dehydrogenation temperature during the dehydrogenation process. Furthermore, when the lubricating oil temperature reaches the set dehydrogenation temperature, the PLC activates the coil of the fourth intermediate relay KA4, which in turn activates the coil of the second contactor KM2. The contactor engages, and the timer starts counting.

[0031] The second temperature controller operates based on the lubricating oil temperature: if the lubricating oil temperature is higher than the set lubricating oil exhaust temperature, the second temperature controller outputs an exhaust signal to the PLC. The PLC then activates the coil of the first intermediate relay KA1, which in turn activates the coil of the first contactor KM1. The contactor engages, and the fan motor starts to exhaust the lubricating oil. If the lubricating oil temperature is lower than the set lubricating oil exhaust temperature, the second temperature controller disconnects the exhaust signal to the PLC. The PLC then disconnects the coil of the first intermediate relay KA1, and the fan motor stops exhausting the lubricating oil.

[0032] Step 3: When the timer reaches the set hydrogen removal time, the PLC controls the buzzer to sound and the yellow indicator light to illuminate. The buzzer will stop automatically after three minutes, the process is complete, the PLC automatically controls the equipment to stop, and the parts are removed after the lubricating oil cools down. Hydrogen removal is complete.

[0033] Beneficial effects:

[0034] This utility model provides an automatic control system for a lubricating oil furnace. Based on a programmable control chip, a human-machine interface, a switching power supply, and a series of sensors and switches, the automatic control system for the lubricating oil furnace can remotely and automatically realize hydrogen removal operations for aerospace parts, which is beneficial to the health of operators and can strictly maintain the oil temperature of the lubricating oil to meet the hydrogen removal requirements, avoiding the situation of exceeding the upper temperature limit. Attached Figure Description

[0035] Figure 1 This is a circuit schematic diagram of an embodiment of the present utility model;

[0036] Figure 2 This is a schematic diagram illustrating the operation of an embodiment of the present utility model. Detailed Implementation

[0037] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments:

[0038] like Figures 1 to 2 As shown, an automatic control system for a lubricating oil furnace includes a control unit, an execution unit, and a sensing unit.

[0039] The control unit includes a human-machine interface (HMI) for the lubricating oil furnace, a programmable logic controller (PLC), and a switching power supply (SMPS). The PLC includes input terminals and output terminals. The switching power supply converts 220V AC power to 24V DC power to supply power to the HMI and the PLC output terminals. The HMI is connected to the PLC via a communication cable and displays the status parameters of the lubricating oil furnace's automatic control system, providing an interface for manual input of commands. The control unit receives all commands from the HMI and input signals from the PLC, and after logical judgment, sends control commands to the PLC output terminals.

[0040] The actuator is connected to the output of the programmable logic controller (PLC) in the control unit via a communication cable. It is responsible for driving the actuators in the lubricating oil furnace through a series of intermediate relays according to the control commands from the control unit. The actuator includes a first intermediate relay KA1, a second intermediate relay KA2, a third intermediate relay KA3, a fourth intermediate relay KA4, a fifth intermediate relay KA5, a red indicator light, a yellow indicator light, a green indicator light, and a buzzer. The actuators in the lubricating oil furnace include the exhaust fan motor and the first heater R1 and the second heater R2 for heating the lubricating oil.

[0041] The sensing unit is connected to the input terminal of the control unit PLC via a communication cable, and is responsible for feeding back a series of sensor signals in the lubricating oil furnace to the control unit PLC. The sensing unit includes a first oil temperature controller, a second temperature controller, a third temperature controller, an upper oil level sensor, a high oil level sensor, a middle-high oil level sensor, a low oil level sensor, a fan thermal relay feedback terminal, a timer, and a grating.

[0042] In this embodiment, the control unit further includes a cabinet and a first circuit breaker QF1, a second circuit breaker QF2, a first contactor KM1, a second contactor KM2, a third contactor KM3, a first solid-state relay SSR1, a second solid-state relay SSR2, a thermal relay FR1, a first fuse FU1, a second fuse FU2, a current transformer 1, and a current transformer 2 installed inside the cabinet.

[0043] The human-machine interface for controlling the lubricating oil furnace is located on the cabinet panel. The first, second, and third temperature controllers are also located on the cabinet panel, while the PLC and switching power supply are located inside the cabinet.

[0044] The first circuit breaker QF1 is a 4-pole switch, and the second circuit breaker QF2 is a 1-pole switch. After the cabinet is connected to 380V AC power through the first circuit breaker QF1, it is divided into three main control circuits. The first main control circuit supplies power to the fan motor after being protected by the first circuit breaker QF1, contactor KM1, and thermal relay FR1. The second main control circuit supplies power to the first heater R1 after being protected by the first circuit breaker QF1, first solid-state relay SSR1, first fuse FU1, and current transformer 1. The third main control circuit supplies power to the second heater R2 after being protected by the first circuit breaker QF1, second solid-state relay SSR2, second fuse FU2, and current transformer 2.

[0045] The first intermediate relay KA1 is connected to contactor KM1, the second intermediate relay KA2 is connected to the first solid-state relay SSR1, the third intermediate relay KA3 is connected to the first solid-state relay SSR2, the fourth intermediate relay KA4 is connected to the second contactor KM2, and the fifth intermediate relay KA5 is connected to the third contactor KM3 to form a secondary control circuit.

[0046] The second circuit breaker QF2 is connected to one of the live wires of the power supply connected to the first circuit breaker QF1. The second circuit breaker supplies power to the secondary control circuit, PLC, and switching power supply in sequence. The switching power supply has a built-in rectifier circuit to convert 220V AC to 24V DC. The output port of the switching power supply is connected to the human-machine interface and the PLC output terminal to supply power to the components of the actuator of the human-machine interface and the PLC output terminal.

[0047] Below the human-machine interface on the cabinet panel is an operation panel, which includes an automatic / manual switch button, a start button, a stop button, a reset button, and an emergency stop button. These buttons are connected to the input terminals of the PLC in the control unit via communication cables. The automatic / manual switch button is used to switch control modes, the start button is used to start automatic operation, the stop button is used to stop the system, the reset button is used to unlock the program and return the system to its initial state after an abnormality is resolved, and the emergency stop button is used for emergency stop.

[0048] In this embodiment, the control unit further includes a remote controller, which is connected to the input terminal of the control unit PLC. The remote controller is equipped with the same automatic / manual switching button, start button, stop button, reset button, and emergency stop button as the operation panel, and can remotely control the same functions as the control panel buttons.

[0049] In this embodiment, in the secondary control circuit, the first intermediate relay KA1 is connected to the contactor KM1 to control the on and off of the power supply path of the fan motor; the second intermediate relay KA2 is connected to the first solid-state relay SSR1 to control the on and off of the power supply path of the first heater R1; the third intermediate relay KA3 is connected to the second solid-state relay SSR2 to control the on and off of the power supply path of the second heater R2; the fourth intermediate relay KA4 is connected to the second contactor KM2 to control the on and off of the three temperature controllers; and the fifth intermediate relay KA5 is connected to the third contactor KM3 to control the on and off of the power supply path of the timer in the sensing unit.

[0050] In this embodiment, the association control between the actuator and the sensor and the lubricating oil furnace is specifically as follows:

[0051] The lubricating oil furnace includes an oil tank, a first heater R1, a second heater R2, thermocouple 1, thermocouple 2, thermocouple 3, two level gauges, an oil dipstick, and an oil extraction fan;

[0052] The oil tank contains lubricating oil; a grating is installed at the opening of the oil tank to detect whether there are people or foreign objects at the opening, serving as a start-up condition; each of the two level gauges has upper and lower floats, and each float has a level sensor, meaning the four floats are respectively equipped with an upper oil level sensor, a high oil level sensor, a mid-high oil level sensor, and a low oil level sensor to measure the lubricating oil level, and the PLC sends the lubricating oil level data to the human-machine interface of the lubricating oil furnace for real-time display; the dipstick is used for visual inspection to check whether the oil level meets the requirements.

[0053] The oil extraction fan is driven by a fan motor and is used to extract lubricating oil vapor and purify the air. The fan motor in the oil extraction fan is powered by the first main control circuit and its on / off state is controlled by the PLC through the first intermediate relay KA1 of the actuator. The feedback terminal of the first thermal relay FR1 is connected to the input terminal of the PLC of the control unit to detect whether the fan motor is overloaded and to provide the PLC with a fan motor overload protection signal. If the fan motor is overloaded, the equipment stops, the red indicator light flashes, the buzzer sounds an alarm, and the human-machine interface prompts that the fan motor is overloaded.

[0054] The first heater R1 and the second heater R2 are located at both ends of the oil tank and are used to heat the lubricating oil in the oil tank to a set temperature. The first heater R1 is powered by the second main control circuit and is controlled by the PLC through the second intermediate relay KA2 of the actuator. The second heater R2 is powered by the third main control circuit and is controlled by the PLC through the third intermediate relay KA3 of the actuator.

[0055] Thermocouple 1, thermocouple 2, and thermocouple 3 are positioned at three different locations in the oil tank to measure the oil temperature at different points within the tank. Thermocouple 1 is connected to temperature controller 1 to control the oil temperature. Thermocouple 2 is connected to temperature controller 2 to control the fan motor. Thermocouple 3 is connected to temperature controller 3 and only measures temperature as a reference for thermocouples 1 and 2. The PLC sends the oil temperatures collected by the three temperature controllers to the human-machine interface of the lubricating oil furnace for real-time display.

[0056] Temperature controller 1, based on the lubricating oil temperature measured by thermocouple 1, outputs a heating signal to the PLC if the lubricating oil temperature is lower than the set value for dehydrogenation. The PLC then activates the coils of the second intermediate relay KA2 and the third intermediate relay KA3, which in turn activates SSR1 and SSR2. SSR1 and SSR2 conduct the heating circuit, and the first heater R1 and the second heater R2 heat the oil, raising its temperature. When the temperature reaches the set value for dehydrogenation, temperature controller 1 disconnects the heating request signal to the PLC, and the PLC disconnects the coils of the second intermediate relay KA2 and the third intermediate relay KA3, stopping the heating and ensuring that the lubricating oil remains at the set dehydrogenation temperature during the dehydrogenation process. Furthermore, when the lubricating oil temperature reaches the dehydrogenation temperature, the PLC activates the coil of the fourth intermediate relay KA4, which in turn activates the coil of the second contactor KM2. The contactor engages, and the timer starts counting. The PLC sends the timer's time to the human-machine interface for real-time display. When the timer reaches the set dehydrogenation time, the PLC controls the buzzer to sound an alarm, and the yellow indicator light illuminates.

[0057] The temperature controller 2, based on the lubricating oil temperature measured by thermocouple 2, outputs a smoke extraction and exhaust signal to the PLC if the lubricating oil temperature is higher than the set value for lubricating oil exhaust temperature. The PLC then activates the coil of the first intermediate relay KA1, which in turn activates the coil of the first contactor KM1. The contactor engages, and the fan motor starts to extract and exhaust the smoke. If the lubricating oil temperature is lower than the set value for lubricating oil exhaust temperature, the temperature controller 2 disconnects the smoke extraction and exhaust signal from the PLC. The PLC then disconnects the coil of the first intermediate relay KA1, and the fan motor stops extracting and exhausting the smoke.

[0058] In this embodiment, the specific steps for automating operations using the aforementioned automatic control system for the lubricating oil furnace are as follows:

[0059] Step 1: Start-up preparation;

[0060] Immerse the parts to be dehydrogenated in the lubricating oil, set the dehydrogenation temperature, dehydrogenation time, and lubricating oil exhaust temperature. The automatic control system of the lubricating oil furnace defaults to the automatic / manual switch button being set to the automatic side. The operator presses the remote start button, the PLC activates the KA4 coil, the normally open contact of KA4 is connected, the temperature controller is powered on, and the equipment enters self-test mode. That is, the PLC checks whether the conditions of each input port meet the normal start-up and operation conditions, including whether the lubricating oil level is within the allowable range, whether there are people or foreign objects in the tank opening, whether the thermal relay is normal, and whether the initial lubricating oil temperature is within the normal range. If the conditions are met, proceed to the next step.

[0061] Step 2: Heat the lubricating oil to the set dehydrogenation temperature and maintain it at that temperature;

[0062] Temperature controller 1, based on the lubricating oil temperature measured by thermocouple 1, outputs a heating signal to the PLC if the lubricating oil temperature is lower than the set value for dehydrogenation. The PLC then activates the coils of the second intermediate relay KA2 and the third intermediate relay KA3, which in turn activates SSR1 and SSR2. SSR1 and SSR2 conduct the heating circuit, and the first heater R1 and the second heater R2 heat the oil, raising its temperature. When the temperature reaches the set value for dehydrogenation, temperature controller 1 disconnects the heating request signal to the PLC. The PLC then disconnects the coils of the second intermediate relay KA2 and the third intermediate relay KA3, stopping the heating process and ensuring that the lubricating oil remains at the set dehydrogenation temperature during the dehydrogenation process. Furthermore, when the lubricating oil temperature reaches the dehydrogenation temperature, the PLC activates the coil of the fourth intermediate relay KA4, which in turn activates the coil of the second contactor KM2. The contactor engages, and the timer starts counting. The PLC sends the timer's time to the human-machine interface for real-time display of the lubricating oil furnace.

[0063] The temperature controller 2, based on the lubricating oil temperature measured by thermocouple 2, outputs a smoke extraction and exhaust signal to the PLC if the lubricating oil temperature is higher than the set value for lubricating oil exhaust temperature. The PLC then activates the coil of the first intermediate relay KA1, which in turn activates the coil of the first contactor KM1. The contactor engages, and the fan motor starts to extract and exhaust the smoke. If the lubricating oil temperature is lower than the set value for lubricating oil exhaust temperature, the temperature controller 2 disconnects the smoke extraction and exhaust signal from the PLC. The PLC then disconnects the coil of the first intermediate relay KA1, and the fan motor stops extracting and exhausting the smoke.

[0064] Step 3: When the timer reaches the set hydrogen removal time, the PLC controls the buzzer to sound and the yellow indicator light to illuminate. The buzzer will stop automatically after three minutes, the process is complete, the PLC automatically controls the equipment to stop, and the parts are removed after the lubricating oil cools down. Hydrogen removal is complete.

[0065] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention without departing from the principles and spirit of the present invention.

Claims

1. An automatic control system for a lubricating oil furnace, characterized in that: It includes a control unit, an execution unit, and a sensing unit; The control unit includes a human-machine interface for the lubricating oil furnace, a programmable logic controller (PLC), and a switching power supply. The PLC includes input terminals and output terminals. The switching power supply converts 220V AC to 24V DC to power the human-machine interface and the PLC output terminals. The human-machine interface for the lubricating oil furnace is connected to the PLC via a communication cable and is used to display the status parameters of the lubricating oil furnace automatic control system and provide an interface for manual input of commands to the lubricating oil furnace automatic control system. The control unit receives all commands from the human-machine interface for the lubricating oil furnace and input signals from the PLC through the PLC, and sends control commands to the output terminals of the PLC after logical judgment. The actuator is connected to the output of the programmable controller in the control unit via a communication cable. It is responsible for driving the actuators in the lubricating oil furnace through a series of intermediate relays according to the control commands of the control unit. The actuator includes a first intermediate relay KA1, a second intermediate relay KA2, a third intermediate relay KA3, a fourth intermediate relay KA4, a fifth intermediate relay KA5, a red indicator light, a yellow indicator light, a green indicator light, and a buzzer. The actuators in the lubricating oil furnace include the fan motor for exhaust and the first heater R1 and the second heater R2 for heating the lubricating oil. The sensing unit is connected to the input terminal of the programmable controller in the control unit via a communication cable, and is responsible for feeding back a series of sensor signals in the lubricating oil furnace to the programmable controller in the control unit. The sensing unit includes a first oil temperature controller, a second temperature controller, a third temperature controller, an upper oil level sensor, a high oil level sensor, a middle-high oil level sensor, a low oil level sensor, a fan thermal relay feedback terminal, a timer, and a grating.

2. The automatic control system for the lubricating oil furnace according to claim 1, characterized in that: The control unit also includes a cabinet and installed in the cabinet are a first circuit breaker QF1, a second circuit breaker QF2, a first contactor KM1, a second contactor KM2, a third contactor KM3, a first solid-state relay SSR1, a second solid-state relay SSR2, a thermal relay FR1, a first fuse FU1, a second fuse FU2, a first current transformer, and a second current transformer. The human-machine interface for controlling the lubricating oil furnace is located on the cabinet panel. The first, second, and third temperature controllers are also located on the cabinet panel. The programmable controller and switching power supply are located inside the cabinet. The first circuit breaker QF1 is a 4-pole switch, and the second circuit breaker QF2 is a 1-pole switch. After the cabinet is connected to 380V AC power through the first circuit breaker QF1, it is divided into three main control circuits. The first main control circuit supplies power to the fan motor after being protected by the first circuit breaker QF1, contactor KM1, and thermal relay FR1. The second main control circuit supplies power to the first heater R1 after being protected by the first circuit breaker QF1, first solid-state relay SSR1, first fuse FU1, and first current transformer. The third main control circuit supplies power to the second heater R2 after being protected by the first circuit breaker QF1, second solid-state relay SSR2, second fuse FU2, and second current transformer. The first intermediate relay KA1 is connected to contactor KM1, the second intermediate relay KA2 is connected to the first solid-state relay SSR1, the third intermediate relay KA3 is connected to the first solid-state relay SSR2, the fourth intermediate relay KA4 is connected to the second contactor KM2, and the fifth intermediate relay KA5 is connected to the third contactor KM3 to form a secondary control circuit. The second circuit breaker is connected to one of the live wires of the power supply connected to the first circuit breaker. The second circuit breaker supplies power to the secondary control circuit, the programmable controller, and the switching power supply in sequence. The switching power supply has a built-in rectifier circuit to convert 220V AC power to 24V DC power. The output port of the switching power supply is connected to the human-machine interface of the lubricating oil furnace and the output terminal of the programmable controller to supply power to the components of the execution part of the human-machine interface and the output terminal of the programmable controller. Below the human-machine interface on the cabinet panel is an operation panel, which includes an automatic / manual switch button, a start button, a stop button, a reset button, and an emergency stop button. These buttons are connected to the input terminal of the programmable controller in the control unit via communication cables. The automatic / manual switch button is used to switch control modes, the start button is used to start automatic operation, the stop button is used to stop the system, the reset button is used to unlock the program and return the system to its initial state after an anomaly is resolved, and the emergency stop button is used for emergency stop.

3. The automatic control system for the lubricating oil furnace according to claim 2, characterized in that: The control unit also includes a remote controller, which is connected to the input terminal of the programmable controller in the control unit. The remote controller is equipped with the same automatic / manual switching button, start button, stop button, reset button, and emergency stop button as the operation panel, and can remotely control the same functions as the control panel buttons.

4. The automatic control system for the lubricating oil furnace according to claim 2, characterized in that: In the secondary control circuit, the first intermediate relay KA1 is connected to the contactor KM1 to control the on and off of the power supply path of the fan motor; the second intermediate relay KA2 is connected to the first solid-state relay SSR1 to control the on and off of the power supply path of the first heater R1; the third intermediate relay KA3 is connected to the second solid-state relay SSR2 to control the on and off of the power supply path of the second heater R2; the fourth intermediate relay KA4 is connected to the second contactor KM2 to control the on and off of the power supply of the three temperature controllers; and the fifth intermediate relay KA5 is connected to the third contactor KM3 to control the on and off of the power supply path of the timer in the sensing unit.

5. The automatic control system for the lubricating oil furnace according to claim 1, characterized in that: The specific control of the linkage between the actuator and the sensor and the lubricating oil furnace is as follows: The lubricating oil furnace includes an oil tank, a first heater R1, a second heater R2, a first thermocouple, a second thermocouple, a third thermocouple, two level gauges, an oil dipstick, and an oil extraction fan; The oil tank contains lubricating oil; a grating is installed at the opening of the oil tank to detect whether there are people or foreign objects at the opening, serving as a start-up condition; each of the two level gauges has upper and lower floats, and each float has a level sensor, i.e., the four floats are respectively equipped with an upper oil level sensor, a high oil level sensor, a mid-high oil level sensor, and a low oil level sensor to measure the lubricating oil level, and the programmable controller sends the lubricating oil level to the human-machine interface of the lubricating oil furnace for real-time display; the dipstick is used for visual inspection to check whether the oil level meets the requirements. The oil extraction fan is driven by a fan motor and is used to extract lubricating oil vapor and purify the air. The fan motor in the oil extraction fan is powered by the first main control circuit and its on / off state is controlled by the programmable controller through the first intermediate relay KA1 of the execution unit. The feedback terminal of the first thermal relay FR1 is connected to the input terminal of the programmable controller in the control unit to detect whether the fan motor is overloaded and to provide the programmable controller with a fan motor overload protection signal. If the fan motor is overloaded, the equipment stops, the red indicator light flashes, the buzzer sounds an alarm, and the human-machine interface prompts that the fan motor is overloaded. The first heater R1 and the second heater R2 are located at both ends of the oil tank and are used to heat the lubricating oil in the oil tank to a set temperature. The first heater R1 is powered by the second main control circuit and is controlled by the programmable controller through the second intermediate relay KA2 of the execution unit. The second heater R2 is powered by the third main control circuit and is controlled by the programmable controller through the third intermediate relay KA3 of the execution unit. A first thermocouple, a second thermocouple, and a third thermocouple are positioned at three different locations in the oil tank to measure the oil temperature at different points. The first thermocouple is connected to a first temperature controller to control the oil temperature. The second thermocouple is connected to a second temperature controller to control the fan motor. The third thermocouple is connected to a third temperature controller and measures only the temperature, serving as a reference for the first and second thermocouples. The programmable controller sends the oil temperatures collected by the three temperature controllers to the human-machine interface of the lubricating oil furnace for real-time display. The first temperature controller, based on the lubricating oil temperature measured by the first thermocouple, outputs a heating signal to the programmable controller (PCC) if the lubricating oil temperature is lower than the set value for dehydrogenation. The PCC then activates the coils of the second and third intermediate relays KA2 and KA3, which in turn activate SSR1 and SSR2. SSR1 and SSR2 conduct the heating circuit, and the first heater R1 and the second heater R2 heat the oil, raising its temperature. When the temperature reaches the set value for dehydrogenation, the first temperature controller disconnects the heating request signal to the PCC. The PCC then disconnects the coils of the second and third intermediate relays KA2 and KA3, stopping the heating and ensuring that the lubricating oil remains at the set dehydrogenation temperature during the dehydrogenation process. Furthermore, when the lubricating oil temperature reaches the set dehydrogenation temperature, the PCC activates the coil of the fourth intermediate relay KA4, which in turn activates the coil of the second contactor KM2. The contactor engages, and the timer starts counting. The PCC sends the timer's time to the human-machine interface of the lubricating oil furnace for real-time display. When the timer reaches the set dehydrogenation time, the PCC controls the buzzer to sound an alarm, and the yellow indicator light illuminates. The second temperature controller, based on the lubricating oil temperature measured by the second thermocouple, outputs a smoke extraction and exhaust signal to the programmable controller if the lubricating oil temperature is higher than the set value for lubricating oil exhaust temperature. The programmable controller then activates the coil of the first intermediate relay KA1, which in turn activates the coil of the first contactor KM1. The contactor engages, and the fan motor starts to perform smoke extraction and exhaust. If the lubricating oil temperature is lower than the set value for lubricating oil exhaust temperature, the second temperature controller disconnects the smoke extraction and exhaust signal from the programmable controller. The programmable controller then disconnects the coil of the first intermediate relay KA1, and the fan motor stops performing smoke extraction and exhaust.

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