Development direction of gear pump hydraulic transmission system

In order to adapt to the rapid development of the hydraulic transmission system in the direction of rapid response, small volume and low noise, in addition to actively taking measures to maintain its dominant position in the low- and medium-pressure quantitative systems and lubrication systems, the gear pumps still need to develop in the following directions:

(1) Low flow pulsation: Flow pulsation will cause pressure pulsation, which will cause the system to generate vibration and noise, which is inconsistent with the requirements of modern hydraulic systems. To reduce the pulsation of the flow, in addition to the measures described in the previous section, the use of a multi-geared pump with a multi-geared Cachuan is a trend.

(2) High pressure: High pressure is required by the system, and it is also a problem that the gear pump must compete with the piston pump and vane pump. The gear pump's high-pressure work has made great progress, but due to its own structure, it is very difficult to further increase the work pressure, and a new structure of gear pump must be developed. In this regard, a compound gear pump composed of a plurality of gears will have great advantages. Many domestic researchers have conducted research on this and have achieved remarkable results.

(3) Low noise; foreign countries have long had "quiet" hydraulic pumps. As people's awareness of environmental protection has increased, the noise requirements for gear pumps have become increasingly stringent. The noise of the gear pump mainly consists of two parts, one part is the mechanical noise generated during the gear meshing process, and the other part is the hydraulic noise generated by the trapped oil impact. The former is related to the processing and installation accuracy of the gears, and the latter depends mainly on whether the pump is completely unloaded. For the external gear pump, it is very difficult to achieve complete unloading, so further reducing the noise of the pump is subject to certain restrictions. In this regard, internal gear pumps have received widespread attention due to their features such as smooth operation, no oil trapping, and low noise. In particular, internal gear pumps with rectilinear conjugate gear profiles are often used due to their smooth operation and low noise. The favor is becoming the focus of research.

(4) Variable displacement; the displacement of the gear pump is not adjustable, limiting its use. In order to change the displacement of the gear pump, domestic and foreign scholars have conducted a lot of research work and achieved many research results. There are many patents on the variable displacement of gear pumps, but they are rarely converted into products. The balanced type compound gear pump can change the displacement of the pump by adjusting the rotation speed of the internal gear, but the specific method and structure need to be further studied.

(5) Large displacement; for some systems that require rapid movement, large displacements are required. However, the increase in the displacement of ordinary gear pumps is limited by many factors. On the one hand, balanced compound gear pumps have significant advantages. For example, the displacement of a three idler compound gear pump is equal to the displacement of six single pump of the same size.