Working principle and fault treatment of HX_N3 locomotive air compressor

Working principle and fault handling of railway locomotive and HXn3 locomotive air compressors Chen Jichao, Chi Qingguang, Wang Laibin, Zhang Wei (Dalian Locomotive & Rolling Stock Co., Dalian, Liaoning 116022, China) The operating principle of the press was introduced and explained in detail. Several solutions for the failure of air compressors. Through the combination of theory and practice, the fault handling of this type of air compressor is made simpler and more efficient.

1:B HXn3 diesel locomotive was jointly developed by China North Locomotive Group Dalian Locomotive and Rolling Stock Co., Ltd. and American EMD Company for trunk freight traction. The locomotive power is 6,000 hp. It is an energy-saving and environment-friendly diesel locomotive with relatively advanced technology and relatively high power in similar products at home and abroad. It has a series of advantages such as continuous traction, low fuel consumption, low emissions, fast running speed and high durability.

The HXn3 locomotive is equipped with two screw air compressor units (hereinafter referred to as air compressors). The air compressor is the total source of the locomotive. It is responsible for compressing the air into the three air cylinders of the locomotive. It is used to realize the functions of air brake, sanding, whistling and blinds switch of the locomotive. In particular, the 1 and 2 air cylinders of the muscle car are the total air cylinders, and the air cylinders are auxiliary air cylinders. The total air cylinder can be filled with air for the 3 air cylinders. When the total air cylinder has no wind, the auxiliary wind pump manual air function can be realized by operating the locomotive Fire display for the locomotive starting.

1 Screw air compressor HXn3 locomotive uses two Knorr-Block SL22-56 screw air compressors as the wind supply for the locomotive. Air compressor rated flow 2400L / min working pressure 9bar, speed 2660r / min In addition to Knorr-Bremse air compressor, this type of locomotive is also equipped with air compressors such as standard tripods. This paper only takes Knorr-Bremse air compressor as an example to explain the principle and troubleshooting method of air compressor.

In the process of compressing air, the outside air first passes through the air filter.

The cleaner enters the compressor and is finally output from the air compressor via compression of the compressor and filtration by the oil separator. Taking into account the performance requirements of the locomotive for the wind source, after the air compressor, the locomotive is equipped with an air dryer, a fine oil separator and a condensate collecting unit.

In order to reduce the starting current of the AC motor driven by the air compressor, the air compressor of the locomotive is equipped with an empty load device. According to the logic requirements of the locomotive, the solenoid valve in the airborne device acts to control the opening and closing of the air intake passage of the air compressor. The solenoid valve is an air compressor air-blowing solenoid valve, and the control coil is MVCCR. The control logic of the coil is provided by the vehicle-mounted microcomputer EM2000 through the digital input-output board DIO300. In other words, the EM2000 controls the operation of the air compressor inverter according to the requirements of the wind. When the air compressor just started working, the coil MVCCR did not immediately power up, and the 4S air channel was closed. The air compressor is started at no load. After a few seconds, the EM2000 issues a control command to the MVCCR to open the air compressor intake passage. Thus, after the operating speed is reached, the air compressor begins to compress the air. Therefore, the no-load device functions to reduce the starting current of the air compressor.

Muscle oil is vital for air compressors. The oil can act to lubricate the machine and dissipate heat. This type of air compressor requires the use of Andrew 3057M lubricant. The air compressor is equipped with an oil/gas composite cooler, which effectively reduces the temperature of the oil and the outlet compressed air. The air compressor is provided with an oil control unit, and the temperature control valve in the oil control unit determines the treatment of the oil according to the oil temperature. When the oil temperature is higher than a certain temperature, the oil starts to dissipate through the oil/gas composite cooler; when the oil temperature is lower than a certain temperature, the oil is heated by the heating sleeve.

Chen Jichao et al.: Working principle of HXn3 locomotive air compressor and fault handling The minimum pressure valve is installed at the air outlet of the air compressor cylinder to establish the minimum pressure required for the oil circulation during air compressor operation. The minimum pressure relief valve is closed when the air compressor starts working. Thus, when the wind is blown, the air pressure in the cylinder of the air compressor can be quickly established to ensure that the oil circulates in the air compressor. When the pressure in the cylinder of the air compressor reaches a certain threshold, the minimum pressure relief valve becomes the open state under the action of the pressure. In this way, compressed air is delivered to the pneumatic system downstream of the locomotive. When the EM2000 controls the air compressor to shut down, the minimum pressure relief valve becomes closed to eliminate the reverse flow of the downstream pneumatic system to the air compressor cylinder. At the same time, the air compressor cylinders are automatically unloaded by the release device.

In order to protect the cylinder of the air compressor, a safety valve is also arranged inside to prevent the pressure in the air compressor chamber from being excessively large and causing an explosion.

For the oil temperature and oil pressure, the EM2000 implements the following three protection functions by monitoring the relevant status of the air compressor.

The air compressor oil temperature is low (CLTS>protection. When the temperature is low, the oil will be emulsified, which is not conducive to lubrication. The air compressor realizes CLTS protection through the internal temperature relay TR. TR is a normally open contact, which is closed The valve value is -20 ° C, and the opening threshold is -10 ° C. When the air pressure of the air compressor is low, the TR acts, the oil starts preheating, and the air compressor is turned into a CLTS protection function. The protection is determined by the air compressor itself.芫成贝3 receives the feedback signal of the CLTS.

The air compressor oil temperature is high (CHTS> protection. The air compressor is internally provided with a series temperature controller TS and a thermal fuse TF. The temperature controller is essentially a temperature relay which is a normally closed point and has an action threshold of 112°. C. As the oil temperature rises, the temperature control valve acts, and the oil begins to dissipate heat through the oil and gas composite cooler. If the oil temperature continues to rise slowly and reaches (112幺, TS disconnects, CHTS protection action, empty The press feeds the CHTS signal back to the EM2000. IVCOOO will lock the air compressor inverter. In addition, the temperature of the fruit oil increases rapidly and the TF fuses, and the CHTS protection will also act to lock the air compressor inverter.

The air compressor oil/gas separation pressure is low (CLSP>protection. The air intake pressure in the air compressor body is less than 2.7 bar, and the compressed air pressure in the cylinder is required to be greater than 6. 5 bar. When the pressure in the air body is greater than 2.7 bar, The air compressor is forbidden to start, and the protection action at this time. Because the pressure inside the machine is too large, the air compressor will exhaust and depressurize through the release valve.

2 Electrical working principle 2.1 Main circuit The two air compressors have the same power supply mode, but the power supply circuit is independent.

They all adopt the power supply method of "crossing straight". The input AC is provided by the "LI-L3" winding of the auxiliary generator. The alternating current is converted into direct current by a three-phase full-bridge rectifier bridge composed of a diode. Finally, the DC power is converted from a compressor of the air compressor to a three-phase AC power to the three-phase AC motor that drives the air compressor. The 5CF supporting capacitor is connected in parallel with the DC side of the air compressor inverter. The positive side of the DC side is connected in series.

5mH flat wave inductance. Capacitors and inductors act as regulators and filters. Considering the protection of the air compressor inverter, each phase of the AC side of the three-phase full-bridge rectification is connected in series with a fuse to provide short-circuit protection and over-current protection.

2.2 Control circuit The inverter is a child-friendly component controlled by the air compressor. It has four air compressors to supply 60~DC750V DC input interface.

CAN bus socket. Realize real-time communication between the air compressor inverter and the EM2000.

source. The DC74V is taken from the main contact of the air compressor control circuit breaker.

The EM2000 realizes the control and monitoring of the air compressor inverter through the CAN bus. When the inverter detects the DC74V of the PWR input, the inverter starts and waits for the EM2000 control command.

In order to realize the difference between the EM2000 and the two air compressor inverters, the PWR plug has different jumper modes. The "inverter one" PWR3 plug shorts the ferrules 18, 22, 24 to "inverter two". The PWR4 plug shorts the ferrules 18, 23, 24.

The EM2000 controls the air damper and the monitoring of the air compressor status through the multiplexer and DI0300. This part of the line is connected to the terminal block TBAC of the air compressor's own junction box.

There are a total of 9 external wirings in the junction box.

Implement EM2000 to monitor CLSP protection.

Implement EM2000 monitoring of CHTS protection.

The railway locomotive and the motor car ACCB and ACCPA3 are connected to the damper relay coil MVC-CR. The EM2000 controls the no-load device.

7 is connected to ACCPA2, 8 is connected to ACCA. When the oil temperature is lower than -20 °C, TR is closed, the air compressor feeds back to EM2000 and the temperature of the oil is low while the heating casing HTR starts to work. HTR is two parallel heating resistors inside the air compressor (E1 and E2>. When the temperature is higher than -10 °C, TR is disconnected and HTR stops working.

(3) 9 is connected to ACCNA. When the air pressure of the air compressor is low, the CLTS operates, and the HRT is turned on to achieve the heating function of the air compressor to the oil. During the heating of the oil, the air compressor is prohibited from starting.

Explain 2 Air compressor control circuit 3 fault processing Based on the specific introduction of the air compressor control principle, the following lists some common faults in the factory commissioning and machine maintenance, and give specific solutions.

This condition was found to be a line problem during the factory commissioning process. If the line is wired correctly, then DK) 300, air compressor circuit breaker auxiliary contacts and DIP board should be checked.

First determine if the CAN bus connection is reliable. Then check if DC74V is input to the air compressor inverter through PWR and the internal jumper is connected correctly. In the case where the above line is correct and reliable, it can be determined that the inverter communication board is faulty. It is worth mentioning that the inverter will be locked after the CAN bus is mixed into the interference during the repair process.

In addition, a shutdown failure can occur when the drive motor is reversed or the air compressor is protected. The main circuit and control circuit of the air compressor should be checked. In particular, it is pointed out that the first time after the first time the air compressor is started or the main circuit is removed and installed, the fault may be due to motor reversal, but the probability is small. The resolution of such faults should pay more attention to the action of air compressor protection. It is determined whether the "false protection" caused by the wiring problem of the control circuit or the "true protection" caused by the malfunction of the air compressor.

First check the air compressor. In the maintenance process of the machine section, such failures are mostly caused by less oil or deterioration. When it is determined that there is a problem with the oil, it should be handled in accordance with the service manual.

Secondly, for the undercurrent of the air compressor, the DC side fault of the inverter can be prioritized. Diode rectifier bridges and fuses are the focus of inspection. When the fuse is blown or the diode is broken down, the input phase loss of the three-phase full-wave rectifier bridge will inevitably cause the output voltage of the rectifier bridge to be low, so that the inverter input value cannot satisfy the undercurrent fault of the air compressor. If the DC side is checked for faultless J9I3, the circuit between the inverter and the AC drive motor can be checked. After this part of the circuit is removed, the AC drive motor should be checked.

The air compressor is only allowed to start when the PS detects that the air compressor inlet pressure is less than 2.7 bar. In the factory debugging process, such problems are mostly line problems. When it is determined that the line is correct, the action of the solenoid valve PS can be considered.

(5>The air compressor has been working, but it does not charge the total air cylinder, and no fault is recorded in the case of ensuring the correct connection of the pipeline. The cause of the fault may be the malfunction of the air-operated solenoid valve of the no-load device. By viewing Fire DI0300 of the display screen determines that the control logic has been given by EM2000 and further checks the line of DI0300 to the solenoid valve. In the process of factory commissioning, the main problem is the line problem. It is recommended to check the solenoid valve during the maintenance process.

In the maintenance process of the machine section, the cause of the air compressor failure is mostly due to improper maintenance and oil problems. Therefore, after the muscle car is shipped from the factory, the personnel in the machine section should strictly follow the product maintenance manual to avoid unnecessary trouble and loss.

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