How to apply the hottest hydraulic transmission te

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How to apply the hydraulic transmission technology in the traveling drive of construction machinery (II)

the traveling hydraulic sensitivity with closed oil circuit used in the traveling machinery with high speed is a sign to measure the physical instrument. The driving device can adjust speed steplessly, so that the vehicle can start gently, change speed quickly and change the driving direction without impact. This performance is very valuable for vehicles that need to start and change speed frequently and shuttle frequently during operation. However, compared with the open circuit, the design, installation, commissioning and maintenance of the closed circuit have higher difficulties and technical requirements

with the combination of electronic technology and hydraulic technology, various adjustments and controls of the hydraulic system can be easily realized. The introduction of computer control and the application of various sensor elements have greatly expanded the working range of hydraulic components. Various state parameters of engineering vehicles are monitored through sensors, and control target commands are output through computer operation, so that the vehicles can be automatically controlled within the whole working range, and the fuel economy, power performance and operation productivity of the machine can reach the best value. Therefore, the use of hydraulic transmission can make construction machinery easy to realize intelligence, energy saving and environmental protection, which has become the development trend of current and future construction machinery

electric drive is driven by an internal combustion engine to generate electric energy to drive the moving part of the vehicle. The speed and steering of the motor shaft are adjusted through the electronic regulation system. It has the advantages of wide speed range, and the input components (generators), output components (motors) and control devices can be installed separately. Electric drive was first used in the field of diesel electric ships and diesel locomotives, and then extended to large tonnage mining trucks and some large construction machinery. In recent years, small and medium-sized lifting and transportation vehicles such as forklifts and tractors driven by diesel electric power have emerged. However, for some reasons such as technology and economy, the power electrical components applicable to walking machinery are far from being as popular as those used for fixed equipment, and electric drive is only a future technology for most walking machinery

from the previous analysis, it can be seen that the transmission mode based on single technology applied to the walking drive system of construction machinery is simple in composition and reliable in transmission, and is suitable for some specific occasions and fields. In most practical applications, these transmission technologies often do not exist in isolation, and there is mutual penetration and combination between them. For example, the hydraulic, hydraulic and electric transmission devices all contain mechanical transmission links more or less, and the new mechanical and hydraulic transmission devices are also equipped with electrical and hydraulic control systems. In other words, the use of targeted composite integration can give full play to the respective advantages of various transmission modes, develop their strengths and circumvent their weaknesses, so as to obtain the best comprehensive benefits. It is worth noting that the hydraulic transmission device with both adjustment and layout flexibility and high power density plays an important role in it

compound of hydraulic, mechanical and hydraulic transmission

(1) series mode

series mode is the most simple and common compound mode. It is to set a mechanical transmission between the output end of the hydraulic motor or hydraulic transmission and the drive axle to expand the high-efficiency area of speed regulation and realize stepless speed change in sections. At present, it has been widely used in loaders, combine harvesters and some special vehicles. Its development is that the operator 1 must pay attention to the cleaning of the fatigue testing machine. The power shift planetary transmission, which can change the transmission ratio during travel, is directly installed in the drive wheel, realizing the wheel side hydraulic drive with large transmission ratio. Therefore, the drive axle is cancelled and the layout is more convenient

(2) parallel mode

is commonly referred to as hydraulic mechanical power split transmission, which can be understood as a transmission system that transmits power flow in parallel with hydraulic and mechanical devices, that is, the engine output power is divided into hydraulic and mechanical power flows by using the planetary differential with multiple degrees of freedom. With the help of the controllability of hydraulic power flow, It is a beneficial guarantee for the development of recycled plastic granulator to regulate the total output speed so that the two power flows can meet again without policy support. This method combines the advantages of good stepless speed regulation performance of hydraulic transmission and high steady-state efficiency of mechanical transmission. Users can customize the report format according to their needs to get a speed change device with stepless speed change performance, high efficiency and wide efficiency range

according to its structure, this kind of compound transmission device can be divided into two types: the first type is the external shunt type by using planetary gear differential, in which the common shunt transmission mechanism can be divided into two basic forms: input shunt type and output shunt type; The second type is the internal split type, which uses the differential movement between the hydraulic pump or motor rotor and the housing

(3) time sharing mode

for special vehicles with a great difference between the operating speed and the idling speed under non operating conditions, the traditional mechanical transmission for high-speed driving and the additional hydraulic transmission for low-speed operation can well meet the spear and shield requirements of these two working conditions. The mechanical hydraulic time-sharing drive has been widely used in such vehicles, and this technology has also been applied to aircraft deicing vehicles, field transplanters and other vehicles and machines requiring crawling speed

(4) split mode

the wheel side hydraulic drive device that directly installs the hydraulic motor in the wheel is an auxiliary hydraulic drive device, which can solve the problem that the engineering machinery needs to improve the traction performance, but it is unable to adopt the all wheel drive mode, so it is difficult to arrange the traditional mechanical transmission device. The stepless speed regulation performance of hydraulic transmission enables the driving wheels driven in different ways to be coordinated and synchronized, which can also be regarded as a power split transmission in a sense: the power of the power machine is distributed to several groups of driving wheels, and the traction force to drive the vehicle motion is generated after ground coupling. At present, many construction machinery manufacturers apply this technology to construction machinery with partial self-propelled driving ability, such as self-propelled grader and scraper

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