1. Whether it is oil absorption or pressure oil, there must be two or more closed (well sealed and separated from atmospheric pressure) chambers composed of moving parts and non-moving parts, one of which (or several) as the oil absorption cavity and one (or several) as the pressure oil cavity.
2. The size of the closed volume changes periodically with the movement of the moving parts, and the volume changes from small to large - oil absorption, from large to small - pressure oil.
When the volume energy of the closed cavity gradually changes from small to large (the working volume increases), the oil is "absorbed" (in fact, atmospheric pressure presses the oil in), and this cavity is called the oil suction chamber (oil absorption process); When the volume of the closed chamber changes from large to small (the working volume decreases), the pressure discharge is realized, and the cavity is called the pressure oil cavity (oil pressing process). The output flow of the hydraulic pump is related to the volume size of this closed chamber and is proportional to the volume change and the number of changes per unit time, independent of other factors.
3. It has a corresponding oil distribution mechanism to separate the oil absorption area from the pressure oil.
When the closed volume increases to the limit, it must first be separated from the oil suction chamber, and then turned into oil drainage; When the closed volume is reduced to the limit, it must first be separated from the oil discharge chamber, and then converted to oil absorption, that is, the two chambers should be separated by a sealing section or by an oil distribution device (such as disc oil distribution, shaft oil distribution or valve oil distribution). When the pressure and oil suction chambers are connected due to the communication of oil absorption and oil suction chambers, the volume change of the cavity from small to large or from large to small cannot be realized due to the communication of oil absorption and oil pressure chambers (canceling each other out the amount of change), so that the oil suction cavity does not form a certain vacuum degree, so that the oil cannot be absorbed, and there is no oil output in the pressure oil chamber.
