Hydraulic transmission is a widely used transmission mode in modern machinery manufacturing industry. Compared with other transmission modes, hydraulic transmission has certain advantages in some aspects, such as transmission and operation, and it can be applied to many equipment in various machinery industries, such as injection molding machines and paper machines in light industrial machinery; Pile driver, jack, etc. in construction machinery; Folding arm car loader and industrial robot in intelligent machinery.
It mainly uses hydraulic oil as the working medium and transmits power with the help of the pressure generated by hydraulic oil when the sealing volume changes. Various elements are used to form basic control circuits with different functions. Through organic combination of multiple basic control circuits, a hydraulic transmission system with certain control functions is formed. Its main parameters are pressure, flow and power. Now let's briefly introduce the three main parameters in hydraulic transmission.
Three main parameters of hydraulic transmission
1. Pressure
In hydraulic transmission, pressure refers to the normal force on the unit area of hydraulic oil when the hydraulic oil is relatively static. In physics, it is also called pressure, which is usually represented by P, that is, P=F/A, and the unit is Pa. It usually has two representative modes, such as absolute pressure and relative pressure, the former is based on absolute vacuum pressure; The latter is based on atmospheric pressure. In the hydraulic transmission system, the pressure measured by most pressure gauges is basically relative pressure.
In fact, the pressure of hydraulic transmission mainly depends on external load. The hydraulic transmission system supplies oil to the oil cylinder through the oil pump. If the piston is not subject to the resistance of the external load, the piston can move easily, and the pressure in the left cavity will also be very small. If the piston is subject to the resistance of the external load, the piston will move to the right, and the pressure in the left cavity will continue to rise, until the pressure and area in the left cavity can generate a larger thrust to cope with the resistance. Therefore, the formation of pressure is based on external load. If there is no external load, the hydraulic oil will not form pressure.
2. Flow
Flow refers to the volume of hydraulic oil flowing through a certain pipe section in a unit time, which is usually represented by Q, that is, Q=V/T, and the unit is m3/s. In engineering, L/min is used as the unit. In the pipeline, the place where the hydraulic oil flow rate is faster is in the middle of the pipeline, but because the hydraulic oil has a certain viscosity, the hydraulic oil flow rate will be relatively slow when the pipeline flows, so the average flow rate is usually used to calculate, that is, Q=V/A.
In fact, the flow rate in the pipeline mainly depends on the flow rate. When the hydraulic oil flows in the pipeline, if the volume of the hydraulic oil flowing in the unit time is the same, the flow rate of the hydraulic oil will be relatively slow if the pipeline is large; If the pipeline is small, the flow rate of hydraulic oil will be faster. If the volume of hydraulic oil flowing in a unit time is relatively large, the flow of hydraulic oil in the pipeline will be interrupted, or it will be accumulated in the pipeline, which cannot achieve continuity.
3. Power
Power refers to the work done by the pressure of hydraulic oil in unit time, which is transmitted and controlled by the pressure of hydraulic oil in the pipeline, usually represented by P, that is, P=W/T, unit is W, or Kw, while power can be represented by the product of pressure and flow, that is, P=p × Q.
The power of hydraulic transmission usually includes input power and output power. For example, input power refers to the mechanical power driving the hydraulic pump shaft; The output power refers to the working power of the hydraulic pump and other actuating elements in the hydraulic transmission system. If the input power is equal to the output power without calculating various power losses, that is, Fu=Wu.
Source: Jiezhong Robot
