What is the Working Principle of Hydraulic Pump?

The Working Principles of Hydraulic Pump

It is a hydraulic component that provides pressurized liquid for hydraulic transmission and is a kind of pump. Its function is to convert the mechanical energy of the power machine (such as electric motors and internal combustion engines, etc.) into the pressure energy of the liquid. The figure shows the working principle of a single piston pump. The cam is driven by the electric motor to rotate. When the cam pushes the plunger upward, the sealing volume formed by the plunger and cylinder decreases, and the oil is squeezed out from the sealing volume and discharged to the required place by the check valve. When the cam rotates to the descending part of the curve, the spring forces the plunger downward, forming a certain vacuum, and the oil in the tank enters the sealing volume under the action of atmospheric pressure. The cam makes the plunger lift continuously, the sealing volume decreases and increases periodically, and the pump continuously sucks and discharges oil.

Hydraulic Oil Tank

1. Selection of hydraulic oil tank

The main role of the hydraulic oil tank in the hydraulic system for oil storage, heat dissipation, separation of the air contained in the oil and eliminate foam. The selection of the tank should first consider its capacity, generally mobile equipment to take the maximum flow of the pump 2 to 3 times, fixed equipment to take 3 to 4 times; secondly, consider the tank oil level, when the system all hydraulic cylinder out after the tank oil level shall not be lower than the minimum oil level, when the cylinder retracted after the oil level shall not be higher than the highest oil level; finally, consider the tank structure, the traditional tank partition and can not play the role of precipitation of dirt, should be installed along the tank longitudinal A vertical partition should be installed along the longitudinal axis of the tank. One end of this partition and the end plate of the tank is left empty so that the space between the two sides of the partition is connected, and the inlet and outlet of the hydraulic pump is arranged on both sides of the partition at the non-connected end, so that the distance between the inlet and the return is the farthest, and the hydraulic tank plays more of a heat dissipation role.

2. Installation of hydraulic oil tank

According to the different installation positions can be divided into top-mounted, side-mounted and bottom-mounted.

The top-mounted tank installs the hydraulic pump and other devices on the upper cover plate with good rigidity, which is compact and most widely used. In addition, the tank shell can be cast out of the cooling fins to strengthen the heat dissipation effect, that is, to improve the service life of the hydraulic pump.

Side-mounted tank is the hydraulic pump and other devices installed in the fuel tank next to a large area, but the installation and maintenance are very convenient, usually in the system flow and tank capacity is larger when used, especially when a tank to multiple hydraulic pump oil supply. Because the oil level of the side-mounted tank is higher than the hydraulic pump suction port, it has a better oil absorption effect.

Under the tank is placed under the hydraulic pump tank, not only to facilitate the installation and maintenance, and the hydraulic pump suction capacity is greatly improved.

Extended Reading

Water extraction is very important in human production life, so ancient people invented many water lifting apparatus. For example, the ancient Egyptians invented the chain pump in the 17th century B.C., China invented the waterwheel during the Qin and Han dynasties, and the ancient Greek philosopher and scientist Archimedes invented the screw pump. With the development of science and technology, pumps that can be applied to the industrial field began to appear. 1675, Sir Samuel Moran, the royal mechanic of King Charles II of England, was granted a patent for a plunger pump, and the pumps he designed and manufactured were used by many factories in England at that time.

Hydraulic pump in the modern sense is a power element of hydraulic system, which is driven by engine or motor, draws hydraulic oil from hydraulic tank, pressurizes the oil and delivers it to the actuator. Its basic working principle is to make the pump cavity volume change through movement, so as to compress the fluid to make the fluid with pressure energy. Hydraulic pump as the core component of the hydraulic system, often with the oil tank, temperature control components, filters and accumulators and other elements, auxiliary parts together to form a hydraulic pump station.

There are many types of hydraulic pumps, which can be divided into piston pumps, vane pumps, gear pumps, screw pumps, etc. according to the structure; variable pumps and quantitative pumps according to whether the flow is adjustable. Some of these types of hydraulic pumps can also receive external input of high-pressure fluid and convert hydraulic energy into mechanical energy to perform the function of a hydraulic motor.

Hydraulic pump in the mining and metallurgy, electric power, national defense, agriculture, petrochemical, shipbuilding and many other fields are playing a huge role. In the world under the vigorous development of the emergence of many well-known brands, such as Germany Bosch Rexroth, Denmark Danfoss, Japan Kawasaki Heavy Industries, the United States Parker Hannifin. At the same time, the research for the pump makes the hydraulic pump working pressure, energy conversion rate to further improve, but also make the hydraulic pump application areas to be rapidly expanded.