This circuit can replace the standard primary flow control circuit to obtain the maximum output flow.
First, the choice of pump scheme: at present, the working pressure of high temperature oil pump is close to the piston pump, and the combined load sensing scheme provides variable possibilities for high temperature oil pump, which means that the original clear boundary between high temperature oil pump and the piston pump becomes more and more fuzzy. A typical application of this high temperature oil pump circuit is the steering mechanism commonly found on truck cranes, which eliminates a pump. In this loop, the output flow of the pump must be greater than or equal to the required flow of the primary oil circuit, and the secondary flow can be used for it or back to the tank. Constant value primary flow valve (proportional valve) combines primary control with hydraulic pump, eliminating pipeline and eliminating external leakage, thus reducing costs.
. But only through the primary oil port to provide the required flow to the primary oil line, up to its maximum adjustment value. The function of load sensing flow control valve is very similar to the function of fixed flow control: that is, no matter the speed of the pump, the working pressure or the size of the branch pumping flow, all provide a flow. This type of high temperature oil pump circuit is commonly used in garbage truck or power steering pump circuits where hydraulic control is limited to achieve optimum engine speed, as well as in stationary machinery.
Two, dry suction valve: dry suction valve is a kind of pneumatic hydraulic valve, it is used for the pump oil throttling, when the equipment's hydraulic no-load, only the minimal flow (< 18.9t/min) through the pump; When there is load, the full flow suction pump. This loop reduces costs by eliminating the clutch between the pump and prime mover, and also reduces no-load power consumption because the minimal flow through the loop preserves the prime mover power of the equipment. The dry suction valve circuit can be used for switching hydraulic system in any vehicle driven by internal combustion engine, such as garbage loading trucks and industrial equipment. In addition, it also reduces the noise when the pump is unloaded. Because the pressure of the no-load loop is lower than the fixed-value primary flow control scheme, the temperature rise of the loop is low and the no-load power consumption is small.
Three, bypass flow control: bypass flow control valve can be designed with the limited working flow (working speed) range of the group load sensing control valve.
Priority flow control: regardless of the speed of high temperature oil pump, working pressure or the flow size required by the branch, the fixed value of the primary flow control valve can always ensure the flow required by the equipment. Reasonable choice of hydraulic pump scheme one of the determinants, is the cost of the whole system, compared with the price of the piston pump, high temperature pump with its low cost, simple loop, low filtration requirements, has become a practical choice for many applications. Load sensing flow control valve and primary flow control valve, its typical application is power steering mechanism.
Author: Berthed oil pump
