阅读说明：本技术 一种大功率柴油机温度采集模块及使用方法 (High-power diesel engine temperature acquisition module and use method ) 是由 杨迅 韩文琳 于杨 赵文圣 王欢 顾俊杰 徐进 于 2021-08-06 设计创作，主要内容包括：本发明公开了一种大功率柴油机温度采集模块及使用方法,该模块包括电源电路、信号输入电路、运算放大电路、环境温度采样电路、MCU最小系统电路、拨码开关电路、CAN通讯驱动电路、RS485通讯驱动电路、继电器驱动电路；所述信号输入电路与运算放大电路中分别设置跳线和多路复选器,并通过拨码开关电路切换工作程序,以适配PT1000热电阻或K分度热电偶传感器。本发明能够在同一信号输入通道内实现PT1000热电阻、K分度热电偶、无源开关量三种信号采集；本发明与PLC等控制器相比,具有结构简单、成本更为低廉、适用性更灵活的特点,能够满足高速大功率柴油机在船舶系统中的应用。(The invention discloses a high-power diesel engine temperature acquisition module and a use method thereof, wherein the module comprises a power supply circuit, a signal input circuit, an operational amplification circuit, an ambient temperature sampling circuit, an MCU minimum system circuit, a dial switch circuit, a CAN communication drive circuit, an RS485 communication drive circuit and a relay drive circuit; and a jumper and a multi-channel check device are respectively arranged in the signal input circuit and the operational amplification circuit, and a working program is switched by a dial switch circuit so as to adapt to a PT1000 thermal resistor or a K-index thermocouple sensor. The invention can realize three signal acquisition of PT1000 thermal resistor, K-division thermocouple and passive switching value in the same signal input channel; compared with controllers such as a PLC (programmable logic controller) and the like, the controller has the characteristics of simple structure, lower cost and more flexible applicability, and can meet the application of a high-speed high-power diesel engine in a ship system.)

1. The utility model provides a high-power diesel engine temperature acquisition module which characterized in that: the system comprises a power supply circuit, a signal input circuit, an operational amplification circuit, an ambient temperature sampling circuit, an MCU minimum system circuit, a dial switch circuit, a CAN communication drive circuit, an RS485 communication drive circuit, a relay drive circuit, a PT1000 thermal resistance sensor and a K-index thermocouple sensor;

and the signal input circuit and the operational amplification circuit are respectively provided with a jumper and a multi-channel check device for selecting a driving power supply in different power supply circuits and a pull-up resistor in the signal input circuit, and different working programs are switched by a dial switch circuit so as to adapt to a PT1000 thermal resistor or a K-index thermocouple sensor.

2. The high power diesel engine temperature acquisition module according to claim 1, characterized in that: the PT1000 thermal resistor or K-index thermocouple sensor is connected to a signal input circuit through a cable, signals enter an operational amplifier circuit after channel selection is carried out on the signals through an electronic switch, the amplified signals enter an AD input port of an MCU, an application program controls an ADC (analog-to-digital converter) in the MCU to complete digital-to-analog conversion of the signals and carry out corresponding signal processing according to the type of the sensor, the processed signals participate in control strategy operations such as fault judgment, alarm and the like, and the operation results are sent out through a CAN (controller area network) communication drive circuit, an RS485 communication drive circuit and a relay drive circuit.

3. The high power diesel engine temperature acquisition module according to claim 1, characterized in that: the power input of the power circuit adopts DC24V, two conversion power supplies of converting DC24V into DC12V and converting DC12V into DC5V are arranged in the power circuit, DC12V is used for supplying power for the relay drive circuit, the multi-channel electronic switch, the ADC reference power circuit and the ambient temperature sampling circuit, and DC5V is used for supplying power for the sensor signal input circuit, the signal amplification circuit, the MCU minimum system circuit, the CAN communication drive circuit and the RS485 communication drive circuit.

4. The high power diesel engine temperature acquisition module according to claim 1, characterized in that: the operational amplification circuit is provided with two stages of operational amplifiers, the first stage amplification factor is 7.2, the second stage amplification factor is 81, and the comprehensive multiple after two stages of amplification is 583.2; when the sensor is a PT1000 thermal resistor, the second-stage amplifying circuit is changed into a voltage following circuit through jumper selection; the range of the amplified signal is 2.25-3.0802V; when the sensor is a K-index thermocouple, the signal range is 0-4.746V after two-stage amplification.

5. The high power diesel engine temperature acquisition module according to claim 1, characterized in that: the environment temperature sampling circuit adopts an LM35D integrated chip, wherein the + VS pin of the chip is connected with 12V; the GND pin is connected with 0V through two forward voltage drop diodes with the voltage of about 0.3V, and is connected with an ADC conversion interface of the MCU through a voltage follower; the VOUT pin is connected to 0V through a load resistor and is connected to an ADC conversion interface of the MCU after passing through a voltage follower; therefore, the potential of the GND pin is used as the reference of the VOUT pin to change by 10.0mV when the environmental temperature changes by 1 ℃, and the potential change range is-0.6-4.4V.

6. The high power diesel engine temperature acquisition module according to claim 5, characterized in that: the ADC digital-to-analog conversion mode of the environment temperature sampling circuit is that the voltage of an ADC converter sent by a GND pin of an LM35D chip is 0.6V, and the corresponding ADC digital quantity is 492; the LM35D chip VOUT pin sends into ADC converter voltage and changes along with temperature change, every time 1 ℃ changes, voltage signal changes by 10.0mV, and the corresponding ADC digital quantity changes by 8.2, and after the application program obtains the digital quantity corresponding to GND and VOUT, the GND digital quantity is subtracted from the VOUT digital quantity, and then the digital quantity is divided by 8.2, so that the current environment temperature value can be obtained.

7. The high power diesel engine temperature acquisition module according to claim 1, characterized in that: the system also comprises a passive switching value signal input, wherein the passive switching value signal belongs to an extension application mode of a PT1000 thermal resistor application mode, and in the mode, an application program is controlled to execute a corresponding subprogram by switching the 0/1 state of a 2 nd-bit dial switch; the passive switching value signal input end is connected with a passive normally open signal, two ends of the normally open signal are connected with a 10K ohm resistor in parallel, a PT1000 thermal resistor acquisition mode is selected by a jumper, when the input signal is normally open, the input voltage of the ADC is 2.5V, and the corresponding digital value is 2048; when the input signal is closed, the input voltage of the ADC is 0V, and the corresponding digital quantity is 0; when the input signal line is short-circuited, the input voltage of the ADC is 0V, and the corresponding digital quantity is 0; when the input signal line is disconnected, the input voltage of the ADC is 5V, and the corresponding digital quantity is 4095.

8. The high power diesel engine temperature acquisition module according to claim 1, characterized in that: the ADC digital-to-analog conversion mode of the PT1000 thermal resistor is that the temperature is 0-200 ℃, the voltage range of the PT1000 thermal resistor ADC input signal is 2.25-3.0802V, and the corresponding digital value range is 2049-2525; when the sensor signal is short-circuited, the ADC input voltage signal is changed into 0V, and the corresponding digital quantity is 0; when the sensor signal is disconnected, the input voltage signal of the ADC is 5V, and the corresponding digital quantity is 4095.

9. The high power diesel engine temperature acquisition module according to claim 1, characterized in that: the ADC digital-to-analog conversion mode of the K-index thermocouple is that the temperature is 0-200 ℃, the voltage range of an input signal of the ADC of the K-index thermocouple is 0-4.746V, and the corresponding digital quantity range is 0-3890; when the sensor signal is short-circuited, the ADC input voltage signal is changed into 0V, and the corresponding digital quantity is 0; when the sensor signal is disconnected, the input voltage signal of the ADC is 5V, and the corresponding digital quantity is 4095.

10. A method for using a high-power diesel engine temperature acquisition module, which is characterized by using the high-power diesel engine temperature acquisition module as claimed in any one of claims 1 to 9, and comprises the following steps:

step 1: dividing 0-200 ℃ into 8 uniform sections, dividing the sections into 9 interval temperature points, and respectively establishing a PT1000 thermal resistance difference value data table and a K-division thermocouple difference value data table according to the PT1000 thermal resistance division table or the K-division thermocouple division table by using the 9 interval point temperature values and the corresponding ADC digital value;

step 2: storing the PT1000 thermal resistance difference data table and the K-index thermocouple difference data table into an MCU (microprogrammed control Unit);

and step 3: switching the code of the dial switch circuit, and selecting a working program corresponding to the PT1000 thermal resistor or the K-division thermocouple sensor;

and 4, step 4: the sensor works, the MCU minimum system circuit receives ADC digital signals, the application program compares the ADC digital quantity value of the measured temperature with the data difference table in the step 2, and a corresponding temperature section is selected;

and 5: a calculation program preset by the MCU minimum system circuit performs proportional calculation according to the electric signal values corresponding to the upper limit and the lower limit of the selected temperature section and the received ADC signal value to obtain a corresponding temperature value;

step 6: the processed temperature value signals participate in control strategy operations such as fault judgment, alarm and the like, and the operation results are sent out through a CAN communication drive circuit, an RS485 communication drive circuit and a relay drive circuit.

Technical Field

The invention relates to the technical field of diesel engine monitoring, in particular to a high-power diesel engine temperature acquisition module and a using method thereof.

Background

With the continuous improvement of the power performance of the high-speed high-power diesel engine, higher requirements are put forward on the monitoring and protection of key parts, particularly the high-temperature operation detection requirements of a crankshaft bearing and a connecting rod bearing of the diesel engine. Aiming at the practical requirements, in order to solve the problems that the positions of bearing temperature monitoring points of a high-power diesel engine are many, the requirements can be adapted to two types of sensors, namely a thermal resistor and a thermocouple, and the requirements can be flexibly changed into the problem of multiple target requirements of passive switching value signal acquisition, a temperature acquisition module supporting two types of temperature sensors, namely a PT1000 thermal resistor and a K-index thermocouple, needs to be developed.

Disclosure of Invention

In order to overcome the defects in the background art, the invention provides a temperature acquisition module of a high-power diesel engine and a using method thereof. The temperature acquisition module of the high-power diesel engine is provided with 12 paths of signal inputs, 4 paths of passive switching value outputs, 2 paths of CAN bus communication and 1 path of RS485 bus communication; the acquisition of three signals of PT1000 thermal resistor, K graduation thermocouple and passive switching value can be realized in the same signal input channel, and the data exchange in the diesel engine control system is realized through bus communication. The system can be quickly integrated into diesel engine control systems of different models by matching with a flexible control strategy, and the compatibility and expansibility of the system are enhanced.

In order to achieve the purpose, the invention provides the following technical scheme:

a high-power diesel engine temperature acquisition module comprises a power supply circuit, a signal input circuit, an operational amplification circuit, an ambient temperature sampling circuit, an MCU minimum system circuit, a dial switch circuit, a CAN communication drive circuit, an RS485 communication drive circuit, a relay drive circuit, a PT1000 thermal resistor and a K-index thermocouple sensor;

the PT1000 thermal resistor or K-index thermocouple sensor is connected to a signal input circuit through a cable, a signal enters an operational amplifier circuit after channel selection is carried out on the signal through an electronic switch, the amplified signal enters an AD input port of an MCU, an application program controls an ADC (analog-to-digital converter) in the MCU to complete digital-to-analog conversion of the signal and carries out corresponding signal processing according to the type of the sensor, the processed signal participates in control strategy operations such as fault judgment, alarm and the like, and an operation result is sent out through a CAN (controller area network) communication drive circuit, an RS485 communication drive circuit and a relay drive circuit;

and the signal input circuit and the operational amplification circuit are respectively provided with a jumper and a multi-channel check device for selecting a driving power supply in different power supply circuits and a pull-up resistor in the signal input circuit, and different working programs are switched by a dial switch circuit so as to adapt to a PT1000 thermal resistor or a K-index thermocouple sensor.

The power supply input of the power supply circuit adopts DC24V, two conversion power supplies of DC24V to DC12V and DC12V to DC5V are arranged in the power supply circuit, DC12V is used for supplying power for the relay drive circuit, the multi-channel electronic switch, the ADC reference power supply circuit and the ambient temperature sampling circuit, and DC5V is used for supplying power for the sensor signal input circuit, the signal amplification circuit, the MCU minimum system circuit, the CAN communication drive circuit and the RS485 communication drive circuit.

The further optimization scheme is that the operational amplification circuit is provided with two stages of operational amplifiers, the first stage amplification factor is 7.2, the second stage amplification factor is 81, and the comprehensive multiple after two stages of amplification is 583.2; when the sensor is a PT1000 thermal resistor, the second-stage amplifying circuit is changed into a voltage following circuit through jumper selection; the range of the amplified signal is 2.25-3.0802V; when the sensor is a K-index thermocouple, the signal range is 0-4.746V after two-stage amplification.

The further optimization scheme is that the environment temperature sampling circuit adopts an LM35D integrated chip, wherein the + VS pin of the chip is connected with 12V; the GND pin is connected with 0V through two forward voltage drop diodes with the voltage of about 0.3V, and is connected with an ADC conversion interface of the MCU through a voltage follower; the VOUT pin is connected to 0V through a load resistor and is connected to an ADC conversion interface of the MCU after passing through a voltage follower; therefore, the potential of the GND pin is used as the reference of the VOUT pin to change by 10.0mV when the environmental temperature changes by 1 ℃, and the potential change range is-0.6-4.4V.

The further optimization scheme is that the ADC digital-to-analog conversion mode of the environment temperature sampling circuit is that the voltage of the ADC converter sent by a GND pin of an LM35D chip is 0.6V, and the corresponding ADC digital quantity is 492; the voltage of the voltage signal changes by 10.0mV when the voltage of the LM35D chip VOUT pin is sent to the ADC converter to change along with the temperature change, and the voltage signal changes by 8.2 corresponding to the ADC digital quantity when the voltage of the voltage signal changes by 1 ℃; after the application program obtains the digital quantity corresponding to GND and VOUT, the digital quantity of VOUT is used for subtracting the GND digital quantity, and then the digital quantity is divided by 8.2 to obtain the current environment temperature value.

The further optimization scheme is that the system further comprises a passive switching value signal input, wherein the passive switching value signal belongs to an extension application mode of a PT1000 thermal resistor application mode, and in the mode, an application program is controlled to execute a corresponding subprogram by switching 0/1 states of a 2 nd dial switch; the passive switching value signal input end is connected with a passive normally open signal, two ends of the normally open signal are connected with a 10K ohm resistor in parallel, a PT1000 thermal resistor acquisition mode is selected by a jumper, when the input signal is normally open, the input voltage of the ADC is 2.5V, and the corresponding digital value is 2048; when the input signal is closed, the input voltage of the ADC is 0V, and the corresponding digital quantity is 0; when the input signal line is short-circuited, the input voltage of the ADC is 0V, and the corresponding digital quantity is 0; when the input signal line is disconnected, the input voltage of the ADC is 5V, and the corresponding digital quantity is 4095.

The further optimization scheme is that the ADC digital-to-analog conversion mode of the PT1000 thermal resistor is that the temperature is 0-200 ℃, the voltage range of the PT1000 thermal resistor ADC input signal is 2.25-3.0802V, and the corresponding digital value range is 2049-2525; when the sensor signal is short-circuited, the ADC input voltage signal is changed into 0V, and the corresponding digital quantity is 0; when the sensor signal is disconnected, the input voltage signal of the ADC is 5V, and the corresponding digital quantity is 4095.

The further optimization scheme is that the ADC digital-to-analog conversion mode of the K-division thermocouple is that the ADC digital-to-analog conversion mode is in a range of 0-200 ℃, the voltage range of an input signal of the ADC of the K-division thermocouple is 0-4.746V, and the corresponding digital quantity range is 0-3890; when the sensor signal is short-circuited, the ADC input voltage signal is changed into 0V, and the corresponding digital quantity is 0; when the sensor signal is disconnected, the input voltage signal of the ADC is 5V, and the corresponding digital quantity is 4095.

The invention also provides a use method of the high-power diesel engine temperature acquisition module, and the high-power diesel engine temperature acquisition module comprises the following steps:

step 1: dividing 0-200 ℃ into 8 uniform sections, dividing the sections into 9 interval temperature points, and respectively establishing a PT1000 thermal resistance difference value data table (see figure 10) and a K-division thermocouple difference value data table (see figure 11) according to a PT1000 thermal resistance division table or a K-division thermocouple division table by using the 9 interval point temperature values and corresponding ADC digital values;

step 2: storing the PT1000 thermal resistance difference data table and the K-index thermocouple difference data table into an MCU (microprogrammed control Unit);

and step 3: switching codes of the dial switch circuit, and selecting a working program of the PT1000 thermal resistor or the K-division thermocouple sensor;

and 4, step 4: the sensor works, the MCU minimum system circuit receives ADC digital signals, the application program compares the ADC digital quantity value of the measured temperature with the data difference table in the step 2, and a corresponding temperature section is selected;

and 5: a calculation program preset by the MCU minimum system circuit performs proportional calculation according to the electric signal values corresponding to the upper limit and the lower limit of the selected temperature section and the received ADC signal value to obtain a corresponding temperature value;

step 6: the processed temperature value signals participate in control strategy operations such as fault judgment, alarm and the like, and the operation results are sent out through a CAN communication drive circuit, an RS485 communication drive circuit and a relay drive circuit.

Compared with the prior art, the invention has the beneficial effects that:

the invention can realize three signal acquisition of PT1000 thermal resistance, K indexing thermocouple and passive switching value in the same signal input channel, and realize data exchange in a diesel engine control system through bus communication; compared with controllers such as a PLC (programmable logic controller) and the like, the high-speed high-power diesel engine has the characteristics of simple structure, lower cost and more flexible applicability, and can meet the application of the high-speed high-power diesel engine in a ship system.

Drawings

FIG. 1 is a block diagram of a diesel engine temperature acquisition module system according to the present invention;

FIG. 2 is a schematic diagram of a signal input circuit of the present invention;

FIG. 3 is a schematic diagram of an operational amplifier circuit according to the present invention;

FIG. 4 is a schematic diagram of an ambient temperature sampling circuit of the present invention;

FIG. 5 is a schematic diagram of a relay drive circuit of the present invention;

FIG. 6 is a flow chart of input signal sampling according to the present invention;

fig. 7 is a flowchart of PT1000 signal recognition according to the present invention;

FIG. 8 is a flow chart of the K-index thermocouple signal identification of the present invention;

FIG. 9 is a flow chart of the switching value signal identification of the present invention;

FIG. 10 is a table of PT1000 thermal resistance difference data for the present invention;

FIG. 11 is a table of K-index thermocouple difference data in accordance with the present invention.

Detailed Description

The technical solutions in the embodiments of the present invention are clearly and completely described below with reference to the drawings of the present invention, and it is obvious that the described embodiments are only a part of the preferred embodiments of the present invention, and not all embodiments. It should be understood by those skilled in the art that these embodiments are only for explaining the technical principle of the present invention, and are not intended to limit the scope of the present invention.

Example 1: please refer to fig. 1-11;

the invention provides the following technical scheme: a high-power diesel engine temperature acquisition module and a method thereof, wherein a hardware part comprises: the system comprises a power supply circuit, a signal input circuit, an operational amplification circuit, an ambient temperature sampling circuit, an MCU minimum system circuit, a dial switch circuit, a CAN communication drive circuit, an RS485 communication drive circuit and a relay drive circuit; the method comprises the following steps: the method comprises an input signal type conversion method, a PT1000 temperature sensor signal validity identification method, a K-index thermocouple temperature sensor signal validity identification method, a passive switching value signal validity identification method, an environment temperature acquisition method and a sensor temperature acquisition method.

PT1000 thermal resistance, K graduation thermocouple or passive switching value are connected to a signal input circuit through cables, signals enter an operational amplifier circuit after channel selection is carried out through an electronic switch, the amplified signals enter an ADC input port of an MCU, an application program controls an ADC converter inside the MCU to complete analog-to-digital conversion of the signals, corresponding signal processing is carried out according to sensor types, the processed signals participate in control strategy operations such as fault judgment and alarm, and operation results are sent out through a communication drive circuit and a relay drive circuit (see figure 1).

A power supply circuit. According to requirements, power supply input adopts DC24V, two conversion power supplies of converting DC24V into DC12V and converting DC12V into DC5V are arranged in the power supply, DC12V is used for supplying power for a relay drive circuit, a multi-channel electronic switch, an ADC reference power supply circuit and an ambient temperature sampling circuit, and DC5V is used for supplying power for a sensor signal input circuit, a signal amplification circuit, an MCU minimum system circuit, a CAN communication drive circuit and an RS485 communication drive circuit.

A signal input circuit (see fig. 2). The PT1000 is a resistance change type temperature sensor, outputs different resistance values along with temperature change, and the K-division thermocouple outputs a cold end and hot end temperature difference potential, so that the two need to adopt different measurement driving circuits. A jumper wire is additionally arranged in the circuit design, different driving power supplies and pull-up resistors are selected, and PT1000 resistance signals and K-division thermocouple signals are adapted.

An operational amplifier circuit (see fig. 3). The selected sensor signal enters a multi-channel electronic change-over switch, and enters an operational amplification circuit after the channel selection is completed through an application program. According to the requirement of the temperature measurement range of 0-200 ℃, the signal change range of a PT1000 thermal resistor after passing through a signal input circuit is 0.3125V-0.4278V, the signal change range of a K-index thermocouple after passing through the signal input circuit is 0-8.138 mV, and signals after operational amplification need to be unified to be in the range of 0-5V. The operational amplification circuit is provided with two stages of operational amplifiers, the first stage amplification factor is 7.2, the second stage amplification factor is 81, and the comprehensive multiple after two stages of amplification is 583.2. When the sensor is a PT1000 thermal resistor, the second-stage amplifying circuit is changed into a voltage follower circuit (in phase) through jumper selection, and the amplified signal range is 2.25-3.0802V; when the sensor is a K-index thermocouple, the signal range is 0-4.746V after two-stage amplification. The amplified range of the signals of the two types of sensors meets the requirements of the ADC converter on the range of 0-5V and the temperature measurement precision.

An ambient temperature sampling circuit (see fig. 4). Because the measurement principle of the K-index thermocouple sensor requires the compensation of the cold end temperature, the environment temperature sampling circuit is arranged to measure the cold end temperature, and the measured temperature of the hot end of the sensor is obtained after the compensation is calculated through an application program. The environment temperature sampling circuit adopts an LM35D integrated chip, wherein the + VS pin of the chip is connected with 12V; the GND pin is connected with 0V through two forward voltage drop diodes with the voltage of about 0.3V, and is connected with an ADC conversion interface of the MCU through a voltage follower; and the VOUT pin is connected to 0V through a load resistor, and is connected to an ADC conversion interface of the MCU after passing through the voltage follower. When the ambient temperature changes by 1 ℃, the potential of the GND pin is used as a reference VOUT pin and changes by 10.0mV, the change range is-0.6-4.4V, and the measurement range of the ambient temperature from-50 ℃ to +150 ℃ is met.

The MCU minimum system circuit. The MCU selects a 9S12XEP100 series of flying-escale single-chip microcomputers, a 5V power supply, a working capacitor and an 8MHz crystal oscillator are arranged on the periphery of the MCU, and hardware resources comprise a 12-bit ADC (analog-to-digital converter), a general I/O (input/output), a CAN (controller area network), an SCI (serial interface) and the like. The general I/O pin of the MCU is respectively connected with the dial switch circuit, the relay drive circuit and the multi-channel electronic switch address gating circuit; the AD pin is connected with the amplified temperature sensor signal and the environment temperature sampling signal; pins CAN0 and CAN1 are connected with two CAN drive circuits; the SCI pin is connected with an RS485 driving circuit. The MCU completes acquisition and conversion of sensor temperature signals, working mode switching, data communication, fault and alarm processing and relay instruction driving through embedding a compiled exclusive application program.

A dial switch circuit. The dial switch circuit consists of a 4-bit dial switch group and a pull-up resistor, is connected to the universal I/O pin of the MCU, and is matched with the embedded application program to realize input signal type selection and communication bus station address setting.

CAN communication drive circuit. The isolated CAN drivers are included, and pins TXD1, RXD1, TXD2 and RXD2 of the CAN drivers are connected to pins TXCAN0, RXCAN0, TXCAN1 and RXCAN1 of the MCU.

RS485 communication drive circuit. The circuit comprises an isolation type RS485 driver, and TXD pins and RXD pins of the RS485 driver are connected to TXD0 pins and RXD0 pins of the MCU.

The relay drive circuit (see fig. 5). The device comprises a DC12 relay, an NPN type triode, a freewheeling diode and a light emitting diode. The general IO pin of MCU is connected to triode base, and 12V power is connected to relay coil one end, and the coil other end is connected to triode collector, and the triode projecting pole is connected to 0V, and relay coil both ends connect in parallel freewheeling diode, the emitting diode of series connection current-limiting resistance. When the MCU pin outputs a high level, the trigger triode is connected with the collector and the emitter, the relay is closed, and a passive switching value signal is output.

Input signal type conversion method (see fig. 6). The input signal types comprise three types of PT1000 thermal resistors, K-division thermocouples and passive switching values. Jumper wires are respectively arranged in the signal input circuit and the operational amplification circuit and used for switching a hardware circuit to adapt to a PT1000 thermal resistor or a K-index thermocouple sensor; by switching 0/1 state of the 1 st position dial switch, the control application executes the subroutine corresponding to the sensor type. The passive switching value signal input belongs to an extended application mode of a PT1000 thermal resistor application mode, in the extended application mode, an application program is controlled to execute a corresponding subprogram by switching 0/1 states of a 2 nd-bit dial switch, when the state of the dial switch is 0, a PT1000 thermal resistor sensor subprogram is executed, and when the state of the dial switch is 1, a switching value signal subprogram is executed.

PT1000 temperature sensor signal validity identification method (see FIG. 7). The temperature is 0-200 ℃, the voltage range of the PT1000 thermal resistance ADC input signal is 2.25-3.0802V, and the corresponding digital value range is 2049-2525; when the sensor signal is short-circuited, the ADC input voltage signal is changed into 0V, and the corresponding digital quantity is 0; when the sensor signal is disconnected, the input voltage signal of the ADC is 5V, and the corresponding digital quantity is 4095. The application program can judge whether the signal of the sensor is normal, short-circuited or broken through judging the range of the ADC value.

A method for identifying the validity of a signal of a temperature sensor of a K-index thermocouple (see figure 8). The temperature ranges from 0 to 200 ℃, the voltage range of the input signal of the K-division thermocouple ADC ranges from 0 to 4.746V, and the corresponding digital quantity ranges from 0 to 3890; when the sensor signal is short-circuited, the ADC input voltage signal is changed into 0V, and the corresponding digital quantity is 0; when the sensor signal is disconnected, the input voltage signal of the ADC is 5V, and the corresponding digital quantity is 4095. It can be seen from the above that, unlike the PT1000 sensor signal failure determination condition, the application program can only determine two states of signal normal and open circuit by determining the range of the ADC value, and cannot identify the short circuit state.

The passive switching value signal validity identification method (see fig. 9). The signal input end is connected with a passive normally open signal, two ends of the normally open signal are connected with a 10K ohm resistor in parallel, the jumper selects a PT1000 thermal resistor acquisition mode, when the input signal is normally open, the input voltage of the ADC is 2.5V, and the corresponding digital quantity is 2048; when the input signal is closed, the input voltage of the ADC is 0V, and the corresponding digital quantity is 0; when the input signal line is short-circuited, the input voltage of the ADC is 0V, and the corresponding digital quantity is 0; when the input signal line is disconnected, the input voltage of the ADC is 5V, and the corresponding digital quantity is 4095. Therefore, by setting a reasonable ADC numerical range section, the application program can identify the normal open, the normal close and the open circuit of the signal line of the passive switching value input signal.

An ambient temperature acquisition method. The voltage of the ADC converter sent by the GND pin of the LM35D chip is 0.6V, and the corresponding digital quantity is 492; the voltage of the ADC converter is transmitted to the pin VOUT of the LM35D chip to change along with the temperature change, and when the voltage changes by 1 ℃, the voltage signal changes by 10.0mV, which corresponds to 8.2 digital quantity changes. After the application program obtains the digital quantity corresponding to GND and VOUT, the digital quantity of VOUT is used for subtracting the GND digital quantity, and then the digital quantity is divided by 8.2 to obtain the current environment temperature value.

When the temperature-difference-value-division-based multi-stage heat pump is used, a method of a sectional difference value is adopted, 0-200 ℃ is divided into 8 sections, 9 interval temperature points are totally arranged, a thermal resistance difference value data table (see figure 10) and a thermocouple difference value data table (see figure 11) are respectively established for the 9 interval temperature values and the corresponding ADC digital values according to a PT1000 thermal resistance division table and a K division thermocouple division table, and the thermal resistance difference value data tables and the thermocouple difference value data tables are stored in the MCU; switching codes of the dial switch circuit, and selecting a working program of the PT1000 thermal resistor or the K-division thermocouple sensor; the sensor works, the MCU minimum system circuit receives ADC digital signals, the application program compares the ADC digital quantity value of the measured temperature with the data difference value table, and a corresponding temperature section is selected; a calculation program preset by the MCU minimum system circuit performs proportional calculation according to the electric signal values corresponding to the upper limit and the lower limit of the selected temperature section and the received ADC signal value to obtain a corresponding temperature value; the processed temperature value signals participate in control strategy operations such as fault judgment, alarm and the like, and the operation results are sent out through a CAN communication drive circuit, an RS485 communication drive circuit and a relay drive circuit.

The application program carries out data difference table comparison on the ADC digital quantity value of the measured temperature and calculates a temperature value. According to the measuring principle of the sensor, after the PT1000 thermal resistance sensor signal is calculated through the segmentation difference, an actually measured temperature value can be obtained; after the signals of the K-index thermocouple sensor are subjected to the segmented difference calculation, the temperature difference of the cold end and the hot end of the sensor is obtained, and therefore, the measured value of the environment temperature and the temperature difference of the cold end and the hot end of the sensor are accumulated and calculated to obtain the measured temperature value.

The program for calculating the proportion is preset in the MCU, and the specific calculation mode is as follows: k graduation thermocouple formula:

wherein, V_KVoltage value corresponding to K couple, AD_compFor the actual AD value, V, after cold end compensation_{AD_ref}Is an AD reference voltage value.

Wherein, T_KAnd the measured K couple temperature value is obtained. The range of the interval in which the voltage value calculated by the formula (A) is located, K, is judged according to FIG. 11_{V_(m-1)}Is a range lower limit voltage value, K_{V_m}Is the interval upper limit voltage value, K_{T_(m-1)}Is the lower limit temperature value of the interval, K_{T_m}Is the upper limit temperature value of the interval.

PT1000 thermal resistance calculation formula:

wherein, V_PTIs the voltage value corresponding to PT1000 resistance, AD_RRead the AD value, V, for the MCU_{AD_ref}Is an AD reference voltage value.

Wherein R is_PTThe actual resistance value of PT1000 is obtained from the voltage divider circuit.

Wherein, T_PTIs the PT1000 temperature value. According to FIG. 10, the interval range of the resistance value, PT_{R_(m-1)}Is interval lower limit resistance value, PT_{R_m}Is interval upper limit resistance value, PT_{T_(m-1)}For a corresponding interval lower limit temperature value, PT_{T_m}Is the upper limit temperature value of the corresponding interval.

The embodiment has the advantages that three signal acquisition of PT1000 thermal resistor, K-index thermocouple and passive switching value can be realized in the same signal input channel, and data exchange in a diesel engine control system is realized through bus communication; the system can be quickly integrated into diesel engine control systems of different models by matching with a flexible control strategy, and the compatibility and expansibility of the system are enhanced. Compared with controllers such as a PLC (programmable logic controller) and the like, the high-speed high-power diesel engine has the characteristics of simple structure, lower cost and more flexible applicability, and can meet the application of the high-speed high-power diesel engine in a ship system.

It should be noted that: the invention can be used for collecting the temperature signal of the main shaft bushing of the diesel engine, the normal operating temperature of the main shaft bushing of the diesel engine is about 100 ℃, and the design temperature collection range of 0-200 ℃ can meet the operating requirement of the diesel engine. The main shaft bushing temperature sensor is a surface thermocouple and a surface thermal resistor and is specially used for measuring the surface temperature, the appearance structure of the main shaft bushing temperature sensor is customized according to the actual installation requirement, the temperature sensor is installed in a mode of being pasted on the back of a main shaft bushing, a bearing is tightly pasted on the inner side of the main shaft bushing, the temperature of the main bearing is indirectly reflected by measuring the temperature of the back of the main shaft bushing, and signals of the main shaft bushing temperature sensor are matched with a PT1000 or K-index thermocouple.

The invention is not described in detail in the prior art; for a person skilled in the art, various technical features of the above embodiments may be arbitrarily combined, and for the sake of brevity, all possible combinations of the technical features in the above embodiments are not described, however, as long as there is no contradiction between the combinations of the technical features, the combinations should be considered as the scope of the present description; numerous variations, changes, substitutions and alterations of these embodiments will occur to those skilled in the art without further inventive faculty, and all other embodiments resulting from this disclosure are intended to be within the scope of the present invention; the scope of the invention is defined by the appended claims and equivalents thereof.