Master these 4 points of hydraulic pump selection expert tips, novice can easily buy the desired oil pump

Many users who are new to hydraulic pumps are faced with a variety of hydraulic pumps from dozens of brands: do not know which hydraulic pump brand to choose? Not sure which type of hydraulic pump to choose? Don't know what kind of hydraulic pump to use?

In the face of the customer's "100,000 whys about hydraulic pumps", even the sales staff do not know where to start. For this reason, Haozheng Hydraulic collected and summarized the "Hydraulic Pump Selection Method Manual" to teach you how to choose The right hydraulic pump for you! This selection method manual is also applicable to hydraulic pumps of various brands such as Rexroth, Vickers, Parker, Denison and so on.

The primary principle of selecting a hydraulic pump is to satisfy the working conditions of the system, and based on this, select the output, operating pressure and structure type of the hydraulic pump.

1. Select the output flow of the hydraulic pump

Determining the additional flow of the pump The flow of the pump should meet the requirements of the maximum speed of the implementation element, so the output flow qp of the pump should be determined according to the maximum flow and leakage required by the system, that is, qp ≥ Kqmax In the formula, qp is the output flow of the pump (L /min) K-leakage coefficient of the system, usually K=1.1~1.3 (large value for pipeline length and small value for short pipeline); qmax is the maximum flow rate (L/min) required by the implementation of the component practice one by one.

According to the calculated flow, the pump is selected in the following situations: 

1. Assuming that the system is supplied by a single pump to one implementation element, the hydraulic pump shall be selected according to the highest speed requirement of the implementation element.

2. If the system is supplied with oil by a hydraulic pump to several implementation elements, the flow rate required by each implementation element in each period should be calculated, a flow cycle diagram should be made, and the flow rate of the pump should be selected according to the maximum flow rate.

3. Assuming that the system is supplied with oil by dual pumps, a small flow pump is selected according to the requirement of the highest working speed of the working feed; the dynamic feed is supplied by the dual pumps at the same time. Given the oil demand, subtract the flow of the small-flow pump fed by the job from it, that is, the flow of the large-flow pump.

4. When multiple implementing elements act together, the flow rate of the pump should be determined according to the sum of the maximum flow rates of the implementing elements acting together.

5. Assuming that there is an accumulator in the system for the power compensation of the implementation element, the flow standard of the pump can be selected to be smaller.

6. For the system that has always used the saving valve to regulate the speed of the operation process, when determining the flow rate of the pump, the minimum overflow rate of the relief valve should be added (usually 3L/min). After finding the output flow of the pump, select the additional flow according to the commodity sample that is equal to or slightly larger than the calculated pump flow qp.

It is worth noting that:

First, the extra flow of the selected hydraulic pump should not be too much larger than the flow of the practice operation, so as to avoid excessive overflow of the pump and throw away the larger power.
Second, since the effect of leakage is considered when determining the extra flow of the hydraulic pump, the extra flow is larger than the flow required for the calculation, which will make the training speed slightly larger.

Second, select the working pressure of the hydraulic pump

It should be determined according to the maximum working pressure of the hydraulic cylinder, that is, Pp≥Pmax+∑Δp or pp≥kPmax where Pp is the working pressure of the pump (Pa); Pmax is the maximum working pressure of the implementing element (Pa) ∑Δp is the oil inlet and the total pressure of the oil return circuit (Pa>. In the initial calculation, it is desirable to save the speed regulation and the simpler oil circuit (0.2~0.5)MPa;

For a system with a speed control valve and a complicated pipeline in the oil inlet, it is desirable (0.5~1.5>MPa. K is a coefficient, considering the pressure in the pipeline from the hydraulic pump to the implementation element, take K=1.3~1.5. Hydraulic In the pump commodity sample, the additional pressure and maximum pressure value of the pump are indicated.

After calculating Pp, the pump should be selected according to the extra pressure, and the extra pressure of the selected pump should be equal to or higher than the calculated value. In use, it is only allowed to select the hydraulic pump according to the high pressure when the time is short and overloaded, or the plan specified in the product description book.

Three, choose the structure type of hydraulic pump

When the output flow and working pressure of the hydraulic pump are determined, the detailed structure type of the pump can be selected. Compare the determined Pp and qp values ​​with the extra pressure and extra flow on the nameplate of the hydraulic pump to be selected, so that the values ​​on the nameplate are equal to or slightly larger than the Pp and qp values ​​(be careful not to be too large.

1. Under normal circumstances, when the extra pressure is 2.5MPa, the gear pump should be selected; when the extra pressure is 6.3MPa, the vane pump should be selected; if the working pressure is higher, the plunger pump should be selected;

2. Assuming that the load of the machine tool is large, and there are active and slow operation strokes, the pressure-limiting variable vane pump or double vane pump can be selected; it is used in machine tool auxiliary equipment, such as feeding and clamping and other unimportant occasions. Optional low-cost gear pump;

3. When the speed-saving speed regulation is selected, the quantitative pump can be selected; assuming that it is a high-power occasion, when the volume speed regulation or volume saving speed regulation is used, the variable pump must be selected;

4. Vane variable pump is used for medium and low pressure system;

5. Plunger variable pump is used for medium and high pressure system;

6. In extremely delicate occasions, such as mirror grinders, etc., the oil supply pulsation is required to be small, and a screw pump can be selected.

Fourth, choose the speed of the hydraulic pump

When the type and standard of the hydraulic pump are determined, the speed of the hydraulic pump should be selected according to the speed specified in the product sample.