Hydraulic excavator working oil pump flow control mechanism introduction

22 document identification code; hydraulic excavator is the most popular engineering machine in modern construction machinery. The engine of any kind of hydraulic excavator is stable at steady speed. However, at the site construction 0, the working environment is constantly changing. Since the hydraulic pressure of the hydraulic system is determined by the external load. Therefore, the main working oil pump matches the engine in order to maintain a stable power. It is necessary to constantly adjust the output pressure and flow. This means that the excavator itself must have a control mechanism to adjust the work; 1; the output turbulence. Next, the Komatsu hydraulic control machine Han 225 is taken as an example to introduce the flow control mechanism, the composition of the control mechanism and the structure of the structural control mechanism and the structure of the main components of the mechanism.

Control pump 4 1 valve 啼 servo valve jet 丁 丁 阀 0 valve main function is to feel the position of the piston rod by sensing the output oil pressure of the working oil pump 12 to change the position of the piston rod, thereby changing the size of the gap to the control pump The output oil pressure is adjusted to generate a new output control oil pressure core to control the servo valve to control the flow rate of the working pump.

The valve is mainly in the neutral state of the control valve, that is, when the system is not working, when the system is not working, the jet sensor is subjected to the pressure difference of the working oil pressure, which is the largest, from the slide valve, the state valve output oil pressure The user is the smallest, and the work output flow is also reduced.

The role of the service valve is based on it. Out; mountain, of. The person swings the swing lever 7. thereby pushing the servo plunger to control the tilt angle of the working pump swash plate. Change the size of the oil pump flow.

Move, limiting the oil from. The flow to 1. The 00 valve output pressure is reduced to the lowest, that is, the step valve output pressure. lowest. Thereby pushing the servo valve to work and reducing the angle of the main pump swash plate. The main pump flow is reduced. 8.

2 The working principle of the control mechanism 21 When the control valve is in the neutral state, that is, when the system is not working. The jet sensor senses the pressure difference generated by the working oil pressure, which is the largest and the pressure of the upper end of the valve plunger, which is greater than the sum of the spring force and the pressure acting on the bottom of the spool valve, so that the flow rate of the spool valve is small and the plant is small. And to the three-way flow. Big. Thus, history. The valve outputs the pressure body; the minimum is achieved by operating the servo valve to minimize the angle of the working pump swashplate and minimizing the main pump flow. 6, Z2 When the excavator is working at light load, the main pump outlet pressure corpse lowers the curse net slide valve 2 is pushed down by the spring 1, so that the output pressure of the curse valve is the largest. At the same time, the 00 valve slide valve is pushed down by the spring 3, and the valve port is fully opened. From the valve slide valve is pushed up to the 1 valve port passage to open, so that the valve output pressure is maximized.

The servo pump is used to push the main pump to rotate at a large angle, and the flow rate of the main pump is also maximized. Such as 2.3 when the excavator workload, Dagu at this time the main pump outlet pressure increased. The 1-valve spool 2 is caused to be displaced by the plunger 4 or 6. 3. The flow to one port is reduced. The outlet pressure of the 0 valve is reduced by 2, and as the household, 2 is lowered, the pressure at the outlet of the valve is also lowered. As the ruler 2 is lowered, the pressure at the outlet of the 1 valve is also lowered. Thereby, the inclination angle of the chestnut is reduced by the servo valve, and the flow rate of the main pump is reduced.

2.4 When the working oil pressure approaches or exceeds the main relief pressure, at this time, the 10 valve outlet pressure 5, 2 becomes minimum while the 0 valve plunger 5 is subjected to the main chest pressure and the thrust of the valve output pressure is greater than that of the spring 3. When the spring force. In the case of fault detection of the control mechanism of the spool 4, when the flow control mechanism fails, the hydraulic system of the hydraulic excavator may have the following fault phenomena: 1 the system moves at a slow speed 2 the system speed does not follow the external load Change in size 3 When the external load is too large, the engine will decrease in speed. Even turned off. For different fault phenomena, there are different steps to detect and release. 3.1 Control Pump Control The pump outlet pressure is too low, which will cause the system to move slowly. At this point, the outlet pressure can be increased by adjusting the control pump relief valve.

When the valve spool inside the valve is stuck, it will cause the pressure of the 1 valve outlet to remain unchanged regardless of the external load, so the operating speed of the system will not change with the change of the external load. at this time. We must clean or refine the entire valve to return it to normal operation. In order to solve the problem.

33, the valve is detected when the external load is large. When the system pressure is close to the main overflow pressure. If the 00 valve spool is stuck at this time, the flow to the 1 port cannot be reduced. 0 valve outlet pressure will be too large, so the oil pump flow is too large, that is, the oil pump output power is too large, when the oil pump output power is close to or greater than the engine power, the engine will appear to decrease the speed. Or flameout. At this point we should clean the internal valve spool of the 00 valve. Or appropriately reduce the speed of the spring 3 engine.

3.4 The main function of the detection 0 valve is to when the system is not working. Reduce main pump flow and avoid unnecessary power wastage. But when the system starts working. 1; the valve spool still stays in the unopened position 1 , the oil pump flow can not be improved smoothly, the system's action will become slower 3.5 Servo detection servo valve is a component that directly affects the main pump swashplate, such as its spool stuck , the main millet high speed. As system engineering loads increase dramatically. The engine will experience a drop in speed while the speed is maintained at a low speed. System actions will be significantly slower.

It can be seen from the working principle of the above control mechanism. The main oil pump has the smallest flow rate of the oil pump when it is under empty load, when working with load. The flow rate decreases as the pressure increases. Therefore, the power of the oil chestnut is maintained to be stable and matched with the engine. To ensure that the excavator can work normally, the responsible editor Mark Jun is connected to the 辽44 辽J.4.l. The double limit of overcurrent and over capacity is invalid. For example, the air circuit breaker is handed over, and the overcurrent protection of the insect appliance fails; the fuse does not match the electrical appliance or replaces the fuse with another metal wire.

1.4.2 Double protection against leakage is invalid. The line connector is barely bandaged in time, and the metal frame of the electrical equipment is not grounded; the leakage protector fails or the operating current is too large.

14.3 The protective equipment such as insulated gloves and insulated shoes are not properly used.

1.5 Electrical accident prevention measures For the use of 22,38, the overall requirements of the system voltage is to use the phase line system 18 lines; the terminal distribution box switch box must meet the level of power distribution. Two-level protection requirements; electrical equipment must meet the requirements for leakage protection of the brakes. The specific technical requirements have the following aspects.

1.5.1 Power distribution and lighting distribution should be set separately. When the same box is placed, it should be set and clearly marked; the blasting power should be set separately. And the electrical equipment line is erected on different sides of the hole wall, 1.5.2 distribution box switch box must have reliable waterproof measures and good lighting.

The 1.53 air circuit breaker leakage protector has good performance and is sensitive. The closing action current value of the leakage protector in the hole is 30mA.

1.5.4 The power line should be double-insulated cable, and the electrical feng shui pipeline should be reliably grounded.

1.6 Blasting accidents Blasting safety involves a wide range of aspects. In addition to complying with the blasting requirements, the cause of the accident should be considered from the specific operating environment of the tunnel. 1.6.1 When the spark is detonated, the fuse is too short. The staff did not have enough time to evacuate. It is an important reason for the accident. One side recommends an empirical formula to evacuate to a safe distance. The evacuation speed of the person may be 150 mmin; the V fuse speed is determined experimentally. Also refer to the instructions. Ordinary industrial fuses may have an empirical value of 0.16.2 when the power is detonated. The effect of underground stray current induced current on blasting.

1.6.3 When the tunnel is close to pass through. The two pairs are not enough to wear the work surface. The impact of the shot on the other end 1 17 vehicle transport accidents according to the type of tunnel type hole diameter hole diameter and other factors. The hoist can be selected from the hoist of the car hoist. Car transportation efficiency is high. It is convenient to slag and does not need to be shipped back. It is mostly used in long-distance flat hole construction. The winch has unique advantages in the construction of a tunnel with steep slopes or steep slopes. The following is an analysis of the cause of the accident of the car hoist from the human-machine environment.

1.7.1 Factors affecting the transportation of the car 3 The proficiency and mental state of the driver; the steering wheel of the car. The performance of the brake clutch is good with the light, the size of the hole and the illumination inside the hole; whether the road is flat. solid. No water.

1.7.2 Causes of hoist accidents 3 There are people staying on the track, especially under the slope line; the set work brake and the fuse are invalid; the wire rope is subjected to the force exceeding the ultimate strength; (1) The connection between the truck and the wire rope is not strong.

2 Safety management at the construction site is based on two factors: the cause of the accident and the preventive measures to regulate the behavior of the person and the safety status of the object. From the improvement of the construction method. The implementation of the post responsibility system on the safety facilities and the operating environment to carry out construction site safety management. The construction method must meet the design requirements, and make corresponding adjustments according to the deformation of the surrounding rock and support of the geological changes; the post responsibility should be implemented to everyone; the existing safety devices must be regularly checked to see if their performance is normal. When the construction method changes. It is necessary to re-analyze and predict various unsafe factors in tunnel construction. And carry out reliability evaluation to consider whether to increase the necessary safety devices. In order to standardize on-site safety management, tunnel excavation safety inspections can be made according to actual conditions.

Make site management and various safety inspections well documented. Targeted.

3 Concluding remarks due to restrictions on construction conditions and capital investment. The frequency of accidents in tunnels in China is still high. Bringing a lot of pressure to the company. In the international environment of global economic system, we can only better participate in international market competition by continuously updating the management and technical equipment and improving labor protection conditions.

Editor-in-Chief Zeng Weiyue