In the hydraulic system of mechanical engineering, a certain power system is needed to transmit liquid to realize the normal operation of the machine.The commonly used power systems mainly includeGear pump和Plunger pumpThese two forms.This article mainly focuses on the comparative analysis of gear pump and plunger pump technology in mechanical engineering, and points out the technical methods to improve the performance of mechanical equipment.Firstly, the characteristics of gear pumps are summarized respectively, and then the technology of gear pumps and plunger pumps in mechanical engineering is discussed in detail from several aspects such as unloading circuit, flow control, bypass flow control, setting of dry suction valve and selection of hydraulic pumps. application. 

　　1 The unloading circuit can improve the performance of the equipment very well 

　　This kind of component can effectively fuse equipment with high flow rate and equipment with low performance.At this time, the liquid will disperse along the outlet of the equipment, and we can obtain the ideal flow rate value.When it is running, a high-performance device will run the flow along its outlet to the end, which can reduce the output value of the device. In other words, it can reduce the magnetic index to the ideal data.The convenient parts are carried out by human means.The auxiliary spring ensures that the equipment can be opened or closed effectively. When we set up the opening function for the valve, its unreasonable state can be effectively and timely improved.When we manipulate this kind of components, a convenient measure is to use a lever or a doubled device. 

　　The pilot control (pneumatic or hydraulic) unloading valve is an improvement of the control mode, mainly because it can realize the remote operation behavior, without the need for on-site operation.Compared with others, its main advantage is that the valve can be effectively controlled by electricity. In addition to the remote operation behavior we mentioned, it can also work automatically with the help of a computer without manpower, which greatly saves labor. , Is a kind of liberation of productivity, based on these advantages, we define it as a simple and effective way, worthy of our vigorous promotion and use.Most of the parts that need to be carried out artificially are used to carry out relatively high-speed routes. For example, related parts of cranes that have extremely high requirements for operating speed are a typical case.If it is not controlled by commands, it will continue to output flow.However, for a normally open valve, its operating state is that under normal circumstances, the loop will continue to perform output activities with a relatively small flow rate.Pressure sensing unloading is a common solution, and the spring action keeps the unloading valve in its large flow position (left position).When the pressure value reaches the standard data we set in advance.The overflow opening will operate on its own, and the unloading opening will be affected by the relevant force and change to the corresponding orientation, usually when the equipment falls to the right.The pressure sensing unloading valve is basically an automatic unloading component that can be unloaded when the system pressure is reached. It is commonly used in the split of the speed measuring instrument and the hydraulic vise. 

　　The unloading valve in the flow sensing unloading circuit is also pressed to the large flow position (left door) by a spring.The size of the fixed orifice in the valve is determined according to the flow rate required for the better engine speed of the equipment.When the working speed of the engine is greater than our ideal numerical standard, the pressure of the orifice will increase accordingly, and then the unloading opening will automatically change to the corresponding place, usually on the right side of the equipment.Therefore, the adjacent components of the large flow pump are made into a size that can throttle the large flow, so it uses relatively low energy, and the operation is very safe and stable, and the important cost is less, and it has good economic benefits. .Among the many categories, the remarkable operation is to limit the flow rate to reach our ideal value, so that the efficiency of the equipment can be well improved.Or to reasonably restrict the pressure value of the equipment when the speed is relatively fast, we often use transport vehicles that carry domestic and production wastes to this point. 

　　2 Improve performance by setting the flow control index reasonably 

　　Regardless of the pump speed, working pressure or the flow required by the branch, the fixed-value primary flow control valve can always ensure the flow required for the equipment to work.In this circuit, the output flow of the pump must be large or equal to the flow required by the primary oil circuit, and the secondary flow can be used for other purposes or return to the tank.The fixed-value primary flow valve (proportional valve) combines primary control with the hydraulic pump. This has the advantage of not only effectively removing the pipeline setting link, but also reducing the probability of leakage problems, so in a sense, it is very good The cost is controlled and it has very high economic benefits.The typical application of this gear pump circuit is the steering mechanism often seen on truck cranes, which eliminates a pump. 

　　The function of the load-sensing flow control valve is very similar to that of a fixed-value primary flow control: that is, no matter the pump speed, working pressure or branch pumping demand flow, it provides a primary flow.However, the scheme shown only provides the required flow to the primary oil circuit through the primary oil port until its large adjustment value.This loop can replace the standard primary flow control loop to obtain a large output flow. 

　　3 Improve the performance of the equipment by reasonably and effectively controlling the bypass flow 

　　Regarding the bypass flow control, regardless of the pump speed or working pressure, the pump always supplies liquid to the system according to a predetermined large value, and the excess part is discharged back to the fuel tank or the inlet of the pump.This scheme limits the flow of the system and makes it have good performance.The advantage is that the large adjustment flow can be controlled by the loop scale, and the cost can be reduced; the pump and valve are combined into one, and the bypass control of the pump reduces the loop pressure, thereby reducing the pipeline and its leakage. 

　　4Improve performance by setting dry suction valve 

　　The dry suction valve is an air-controlled hydraulic valve, which is used for pumping oil throttling. When the hydraulic pressure of the equipment is empty, only a very small flow is passed through the pump; and when there is a load, the full flow is sucked into the pump.This kind of circuit can save the clutch between the pump and the prime mover, thereby reducing the cost, and also reducing the no-load power consumption, because the extremely small flow through the loop maintains the prime mover power of the equipment.In addition to the advantages mentioned above, it can also effectively alleviate the noise problem caused by the equipment in the state of no load.The dry suction valve circuit can be used in on-off hydraulic systems in any vehicle driven by an internal combustion engine, such as garbage trucks and industrial equipment. 

　　5 Reasonably select the operation plan of the equipment and do a good job in the design 

　　At present, the working pressure of gear pumps is close to that of plunger pumps. The combined load sensing scheme provides variable possibilities for gear pumps, which means that the original clear boundary between gear pumps and plunger pumps has become increasingly blurred NS.The decisive factor in choosing a reasonable hydraulic pump scheme is the cost of the entire system. Compared with expensive plunger pumps, gear pumps have become a practical choice for many applications due to their lower cost, simple circuit, and low filtration requirements. Program. 

　　Through the above description, we have learned a lot of specific methods to improve the working performance of mechanical gear pumps, whether it is through setting the loop, reasonably controlling the bypass flow, or optimizing the design of the scheme, etc., all of which are useful to our work. In practical significance, some of the methods described above are excellent methods obtained through our continuous application experiments, and some are new researches. They need to be continuously verified in the future practical work to verify their rationality. I hope that through this continuous application Improve, better promote the flexibility of our related equipment, and better promote economic development.