volumetric efficiency hydraulic pump made in china

ELIKA is the low-noise, high-efficiency, low-pulsation gear pumpdeveloped in close collaboration with the Faculty of Engineering at the University of Bologna through the generation of a dedicated design software.

ELIKA is a solution for all applications requiring low levels of noiseand high-levels of efficiency, particularly at low speeds. ELIKA in fact reduces noise emissions by as much as 15 dBA with respect to traditional external gear pumps. Maximum working pressures are similar to those for the GHP series (cast iron/aluminium), thus reaching 300 bar. The particular tooth profile without encapsulation furthermore allows a considerable reduction in pressure oscillations and vibrations transmitted to other components connected to the pump (hoses, tank and valves), producing numerous advantages in the circuit. The helical gear effectively guarantees continuity of movement despite the low number of teeth. The low number of teeth also significantly reduces the fundamental frequencies of noise output, making the sound particularly pleasant.

The particularly low level of noise produced by the ELIKA pumpmakes it particularly suitable for applications which currently employ much more expensive technologies such as screw pumps, vane pumps, or internal gear pumps. ELIKA, with its characteristics, is the ideal solution regarding a wide range of specifications such as rotation speed, operating pressure and viscosity. The structure of the ELIKApump minimises leaks and maximises volumetric efficiency in all conditions. ELIKA is therefore particularly suited for applications, which use inverters or variable-speed drives to regulate the speed of the actuators.

"Double Elika is a Solution for external gear pumps that allows the same design of gears previously reserved for individual pumps to be used in modular architectures, to reduce vibrations and noise."

Gear pump: small in size, simple in structure, less demanding on oil cleanliness, and cheaper in price; but the pump shaft is subject to unbalanced force, severe wear, and large leakage.

Vane pump: divided into double-acting vane pump and single-acting vane pump. This kind of pump has uniform flow, stable operation, low noise, higher working pressure and volumetric efficiency than gear pumps, and more complicated structure than gear pumps.

Plunger pump: high volumetric efficiency, small leakage, can work under high pressure, mostly used in high-power hydraulic systems; but the structure is complex, the material and processing accuracy requirements are high, the price is expensive, and the oil cleanliness requirements are high.

Following ISO9000/TS16949 quality management system standards, GRH uses ERP production management systems to provide high quality hydraulic products for customers. To purse advanced technology, GRH is equipped with 305 sets of various machining centers and equipment, including a German high speed cutting center, American honing machine, special diamond boring machine and more. Strict processes and management keep the assembly process always under control. All the delivered products will be 100% tested and inspectors conduct sampling inspection according to international standards. Strict control over time, pressure, temperature, flow, stroke and other parameters ensures the quality stability and reliability of outgoing products.Advanced technologies, reliable quality and performance, and a meticulous service spirit allow GRH to be highly recognized by worldwide customers.

The pressure boundary conditions are imposed on the inlet and the outlet. And the boundary conditions of mode are given according to the practical operation in seawater hydraulic motor. The rated pressure of the motor is 10 MPa, so the pressure of inlet is set to 10 MPa. Meanwhile, due to the leakage of clearance of port plate pairs and piston pairs, the pressure boundary conditions are also imposed on the side of water film and the pressure of outlet is 0.5 MPa.

Through the analysis of the effect of water film thicknesses on pressure distribution, velocity distribution and the leakage flow, it can be denoted that when the water film is 10 μm, the leakage flow will very large and the volumetric efficiency will very low. It doesn’t conform to practical applications. When the water film are 4 μm and 6 μm, the pressure and velocity distribution are obviously unsatisfactory, and even appear to negative pressure which will cause the cavitation damage of port plate pairs. When the water film is 8 μm, the pressure distribution and velocity distribution are more balanced. Consequently, taking the pressure distribution, velocity distribution, leakage flow and manufacture into consideration, the water film thickness should be controlled at about 6‒8 μm.

By comparing these pressure contour pictures, it can be seen that the pressure distribution has slightly different when the inlet pressure is 5 MPa and the other three pressures (10 MPa, 15 MPa and 20 MPa). When the inlet pressure is 5 MPa, the pressure distribution is similar to a radial distribution. And the distribution of other three pressures trend to circumferential distribution. Overall, there is not much difference between the four distributions. Thus, the inlet pressure of seawater hydraulic motor has no significant effect on the pressure distribution of port plate pairs.

Figure 13 shows the change of leakage flow of port plate pairs with inlet pressure at different time. As shown in the figure, the leakage flow of CFD simulation also rises with increased inlet pressure. When the inlet pressure is 5 MPa, the port plate pairs exhibit the lowest average leakage flow as 0.18 L/min, whereas it shows the highest average leakage flow of 0.75 L/min under the 20 MPa. The CFD simulation trend of leakage flow is coincided with theoretical calculation, as shown in Figure 3. Viewed from the numerical results, the leakage flow changes linearly with increasing inlet pressure. So the inlet pressure of seawater hydraulic motor should not too high.

In a condition-based maintenance environment, the decision to change out a hydraulic pump or motor is usually based on remaining bearing life or deteriorating efficiency, whichever occurs first.

Despite recent advances in predictive maintenance technologies, the maintenance professional’s ability to determine the remaining bearing life of a pump or motor, with a high degree of accuracy, remains elusive.

Deteriorating efficiency on the other hand is easy to detect, because it typically shows itself through increased cycle times. In other words, the machine slows down. When this occurs, quantification of the efficiency loss isn’t always necessary. If the machine slows to the point where its cycle time is unacceptably slow, the pump or motor is replaced. End of story.

In certain situations, however, it can be helpful, even necessary, to quantify the pump or motor’s actual efficiency and compare it to the component’s native efficiency. For this, an understanding of hydraulic pump and motor efficiency ratings is essential.

There are three categories of efficiency used to describe hydraulic pumps (and motors): volumetric efficiency, mechanical/hydraulic efficiency and overall efficiency.

Volumetric efficiency is determined by dividing the actual flow delivered by a pump at a given pressure by its theoretical flow. Theoreticalflow is calculated by multiplying the pump’s displacement per revolution by its driven speed. So if the pump has a displacement of 100 cc/rev and is being driven at 1000 RPM, its theoretical flow is 100 liters/minute.

Actualflow has to be measured using a flow meter. If when tested, the above pump had an actual flow of 90 liters/minute at 207 bar (3000 PSI), we can say the pump has a volumetric efficiency of 90% at 207 bar (90 / 100 x 100 = 90%).

Its volumetric efficiency used most in the field to determine the condition of a hydraulic pump - based on its increase in internal leakage through wear or damage. But without reference to theoretical flow, the actual flow measured by the flow meter would be meaningless.

A pump’s mechanical/hydraulic efficiency is determined by dividing thetheoretical torque required to drive it by the actual torque required to drive it. A mechanical/hydraulic efficiency of 100 percent would mean if the pump was delivering flow at zero pressure, no force or torque would be required to drive it. Intuitively, we know this is not possible, due to mechanical and fluid friction.

Table 1. The typical overall efficiencies of hydraulic pumps, as shown above, are simply the product of volumetric and mechanical/hydraulic efficiency.Source: Bosch Rexroth

Like theoretical flow, theoretical drive torque can be calculated. For the above pump, in SI units: 100 cc/rev x 207 bar / 20 x p = 329 Newton meters. But like actual flow, actual drive torque must be measured and this requires the use of a dynamometer. Not something we can - or need - to do in the field. For the purposes of this example though, assume the actual drive torque was 360 Nm. Mechanical efficiency would be 91% (329 / 360 x 100 = 91%).

Overall efficiency is simply the product of volumetric and mechanical/hydraulic efficiency. Continuing with the above example, the overall efficiency of the pump is 0.9 x 0.91 x 100 = 82%. Typical overall efficiencies for different types of hydraulic pumps are shown in the Table 1.

System designers use the pump manufacturers’ volumetric efficiency value to calculate the actual flow a pump of a given displacement, operating at a particular pressure, will deliver.

As already mentioned, volumetric efficiency is used in the field to assess the condition of a pump, based on the increase in internal leakage due to wear or damage.

When calculating volumetric efficiency based on actual flow testing, it’s important to be aware that the various leakage paths within the pump are usually constant. This means if pump flow is tested at less than full displacement (or maximum RPM) this will skew the calculated efficiency - unless leakage is treated as a constant and a necessary adjustment made.

For example, consider a variable displacement pump with a maximum flow rate of 100 liters/minute. If it was flow tested at full displacement and the measured flow rate was 90 liters/minute, the calculated volumetric efficiency would be 90 percent (90/100 x 100). But if the same pump was flow tested at the same pressure and oil temperature but at half displacement (50 L/min), the leakage losses would still be 10 liters/minute, and so the calculated volumetric efficiency would be 80 percent (40/50 x 100).

The second calculation is not actually wrong, but it requires qualification: this pump is 80 percent efficient at half displacement. Because the leakage losses of 10 liters/minute are nearly constant, the same pump tested under the same conditions will be 90 percent efficient at 100 percent displacement (100 L/min) - and 0 percent efficient at 10 percent displacement (10 L/min).

To help understand why pump leakage at a given pressure and temperature is virtually constant, think of the various leakage paths as fixed orifices. The rate of flow through an orifice is dependant on the diameter (and shape) of the orifice, the pressure drop across it and fluid viscosity. This means that if these variables remain constant, the rate of internal leakage remains constant, independent of the pump"s displacement or shaft speed.

Overall efficiency is used to calculate the drive power required by a pump at a given flow and pressure. For example, using the overall efficiencies from the table above, let us calculate the required drive power for an external gear pump and a bent axis piston pump at a flow of 90 liters/minute at 207 bar:

As you’d expect, the more efficient pump requires less drive power for the same output flow and pressure. With a little more math, we can quickly calculate the heat load of each pump:

No surprise that a system with gear pumps and motors requires a bigger heat exchanger than an equivalent (all other things equal) system comprising piston pumps and motors.

Hydraulic losses relates to the construction of the pump or fan and is caused by the friction between the fluid and the walls, the acceleration and retardation of the fluid and the change of the fluid flow direction.

Mechanical components - like transmission gear and bearings - creates mechanical losses that reduces the power transferred from the motor shaft to the pump or fan impeller.

Due to leakage of fluid between the back surface of the impeller hub plate and the casing, or through other pump components - there is a volumetric loss reducing the pump efficiency.

The overall efficiency is the ratio of power actually gained by the fluid to power supplied to the shaft. The overall efficiency can be expressed as: η= ηh ηm ηv(4)

The losses in a pump or fan converts to heat that is transferred to the fluid and the surroundings. As a rule of thumb - the temperature increase in a fan transporting air is approximately 1oC.

An inline water pump works between pressure1 bar (1 105 N/m2)and 10 bar (10 105 N/m2).The density of water is 1000 kg/m3. The hydraulic efficiency is ηh= 0.91.

Model NO.: A6V Professional R&D Team: Capable of Tailor Made Products Enough Heat Treatmment: More Firm&Reliable Factory Made Products: Competitive Price Hydraulic Fluid: Mineral oil Hydraulic Actuator: Hydraulic Cylinder Piston Trademark: Taige Origin: Hefei China Type: Model Type Displacement

Contact us if you need more details on Plunger Pump. We are ready to answer your questions on packaging, logistics, certification or any other aspects about

The simple construction ensures limited purchase costs and servicing. Thanks to there basic concepts, together with ever-improving product design and features, research-based on many years of experience, accuracy in material selection, producing process followed in great detail and tests on mass-produced parts, our gear pumps have reached top quality standards.

For this reason, our products can work under heavy operating conditions and transmit high hydraulic power. Furthermore,SJ-TECHNOLOGY gear pumps feature good hydraulic, mechanical and volumetric efficiency, low noise lever and, last but not least, compact dimensions.

SJ Technology gear pumps has further developed its own range of products with a new series of pumps named GPM where groups names 1P, 1A, GPM0.0, GPM1.0, GPM2.0, GPM2.6, GPM3.0 are suitable for the most different applications in both industrial, mobile, marine and aerospace industries.

Generally these gear pumps, usually consist of a gear pair supported by two aluminum bushes, a body, a securing flange and a cover. Shaft of the driving gear projecting beyond the flange mounts a twin-lip seal ring (the inner lip being a seal and the outer being a dust seal). An elastic securing ring secures the ring in place. The body of the pump is made of special hi-resistant aluminum alloy obtained through extrusion process, while flange and cover are made out of spheroidal cast iron, this in order to ensure minimized deformation even when subject to high pressure, be it continuous or intermittent or peak pressure.

Gears are made of special steel. Their manufacturing process ground and fine finished so to have a high degree of surface ensure low pulsation levers and low noise levers during pump operation.

Special compensation zones onto bushings, insulated by special preformed seals with anti-extrusion ring, allow fully free axial and radial movement to the bushes, which is proportional to pump operating pressure. In this way, internal dripping is dramatically reduced, thus ensuring very good pump performance (both in terms of volume and in general) and proper lubrication of pump moving parts.

Changzhou Green Hydraulics Manufacture Co., Ltd. (formerly known as Changzhou Green Fluid Technology Co., Ltd) is located in Xuejia Industry Zone, New Hi-tech District, Changzhou. Green Hydraulics is a modern and powerful company which concentrates on hydraulic parts and system. We has listed on Jiangsu Equity Exchange Center successfully on October 18th, 2015. The stock code is 690281.

Green Hydraulics has a series of advanced manufacturing machines, imported high-precision stator and rotor grinding machine, Korean AM Parallel Grinding Machine, Thailand Youjia machining center, CNC lathes and so on. Our company is people oriented and owns a professional team. They are constantly pursuing for product research and development. Currently Green Hydraulics can produce 20,000 sets hydraulic pumps per year.

Green Hydraulicis specialized in the design, manufacture, sales of hydraulic pumps, vane pumps, oil pumps and vane motors. We supply a wide range of products, such as Denison T6 series, Denison motor M4C series ,Eaton Vickers V, VQ, V10, V20 ,VTM42 power steering pump series, Eaton Vickers vane motors 25M 35M 45M 50M series, Tokimec SQP series,50T 150T and Yuken PV2R series.

The products are widely applied in mining construction machinery, materials handling equipment, heavy metallurgical machinery, petroleum mining machinery, ship deck machinery, machine tools, light industry, plastic machinery, geological drilling equipment, agricultural and forestry machinery, mineral machinery, construction equipment, and work platform, lawn mowers, special vehicles, fishing winches, machine tools, woodworking and sawing machines, rubber machinery and other machinery in the hydraulic system.

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A hydraulic pump is a mechanical device that converts mechanical power into hydraulic energy. It generates flow with enough power to overcome pressure induced by the load.

A hydraulic pump performs two functions when it operates. Firstly, its mechanical action creates a vacuum at the pump inlet, subsequently allowing atmospheric pressure to force liquid from the reservoir and then pumping it through to the inlet line of the pump. Secondly, its mechanical action delivers this liquid to the pump outlet and forces it into the hydraulic system.

The three most common hydraulic pump designs are: vane pump, gear pump and radial piston pump. All are well suited to common hydraulic uses, however the piston design is recommended for higher pressures.

Most pumps used in hydraulic systems are positive-displacement pumps. This means that they displace (deliver) the same amount of liquid for each rotating cycle of the pumping element. The delivery per cycle remains almost constant, regardless of changes in pressure.

Positive-displacement pumps are grouped into fixed or variable displacement. A fixed displacement pump’s output remains constant during each pumping cycle and at a given pump speed. Altering the geometry of the displacement chamber changes the variable displacement pump’s output.

Fixed displacement pumps (or screw pumps) make little noise, so they are perfect for use in for example theatres and opera houses. Variable displacement pumps, on the other hand, are particularly well suited in circuits using hydraulic motors and where variable speeds or the ability to reverse is needed.

Applications commonly using a piston pump include: marine auxiliary power, machine tools, mobile and construction equipment, metal forming and oil field equipment.

As the name suggests, a piston pump operates through pistons that move back and forth in the cylinders connected to the hydraulic pump. A piston pump also has excellent sealing capabilities.

A hydraulic piston pump can operate at large volumetric levels thanks to low oil leakage. Some plungers require valves at the suction and pressure ports, whilst others require them with the input and output channels. Valves (and their sealing properties) at the end of the piston pumps will further enhance the performance at higher pressures.

The axial piston pump is possibly the most widely used variable displacement pump. It’s used in everything from heavy industrial to mobile applications. Different compensation techniques will continuously alter the pump’s fluid discharge per revolution. And moreover, also alter the system pressure based on load requirements, maximum pressure cut-off settings and ratio control. This implies significant power savings.

Two principles characterise the axial piston pump. Firstly the swash plate or bent axis design and secondly the system parameters. System parameters include the decision on whether or not the pump is used in an open or closed circuit.

The return line in a closed loop circuit is under constant pressure. This must be considered when designing an axial piston pump that is used in a closed loop circuit. It is also very important that a variable displacement volume pump is installed and operates alongside the axial piston pump in the systems. Axial piston pumps can interchange between a pump and a motor in some fixed displacement configurations.

The swivel angle determines the displacement volume of the bent axis pump. The pistons in the cylinder bore moves when the shaft rotates. The swash plate, in the swash plate design, sustain the turning pistons. Moreover, the angle of the swash plate decides the piston stroke.

In general, the largest displacements are approximately one litre per revolution. However if necessary, a two-litre swept volume pump can be built. Often variable-displacement pumps are used, so that the oil flow can be adjusted carefully. These pumps generally operate with a working pressure of up to 350–420 bars in continuous work

Radial piston pumps are used especially for high pressure and relatively small flows. Pressures of up to 650 bar are normal. The plungers are connected to a floating ring. A control lever moves the floating ring horizontally by a control lever and thus causes an eccentricity in the centre of rotation of the plungers. The amount of eccentricity is controlled to vary the discharge. Moreover, shifting the eccentricity to the opposite side seamlessly reverses the suction and discharge.

Radial piston pumps are the only pumps that work continuously under high pressure for long periods of time. Examples of applications include: presses, machines for processing plastic and machine tools.

A vane pump uses the back and forth movement of rectangle-shaped vanes inside slots to move fluids. They are sometimes also referred to as sliding vane pumps.

The simplest vane pump consists of a circular rotor, rotating inside of a larger circular cavity. The centres of the two circles are offset, causing eccentricity. Vanes slide into and out of the rotor and seal on all edges. This creates vane chambers that do the pumping work.

A vacuum is generated when the vanes travel further than the suction port of the pump. This is how the oil is drawn into the pumping chamber. The oil travels through the ports and is then forced out of the discharge port of the pump. Direction of the oil flow may alter, dependent on the rotation of the pump. This is the case for many rotary pumps.

Vane pumps operate most efficiently with low viscosity oils, such as water and petrol. Higher viscosity fluids on the other hand, may cause issues for the vane’s rotation, preventing them from moving easily in the slots.

Gear pumps are one of the most common types of pumps for hydraulic fluid power applications. Here at Hydraulics Online, we offer a wide range of high-powered hydraulic gear pumps suitable for industrial, commercial and domestic use. We provide a reliable pump model, whatever the specifications of your hydraulic system. And we furthermore ensure that it operates as efficiently as possible.

Johannes Kepler invented the gear pump around year 1600. Fluid carried between the teeth of two meshing gears produces the flow. The pump housing and side plates, also called wear or pressure plates, enclose the chambers, which are formed between adjacent gear teeth. The pump suction creates a partial vacuum. Thereafter fluid flows in to fill the space and is carried around the discharge of the gears. Next the fluid is forced out as the teeth mesh (at the discharge end).

Some gear pumps are quite noisy. However, modern designs incorporating split gears, helical gear teeth and higher precision/quality tooth profiles are much quieter. On top of this, they can mesh and un-mesh more smoothly. Subsequently this reduces pressure ripples and related detrimental problems.

Catastrophic breakdowns are easier to prevent with hydraulic gear pumps. This is because the gears gradually wear down the housing and/or main bushings. Therefore reducing the volumetric efficiency of the pump gradually until it is all but useless. This often happens long before wear causes the unit to seize or break down.

Can hydraulic gear pumps be reversed? Yes, most pumps can be reversed by taking the pump apart and flipping the center section. This is why most gear pumps are symmetrical.

External gear pumps use two external spur gears. Internal gear pumps use an external and an internal spur gear. Moreover, the spur gear teeth face inwards for internal gear pumps. Gear pumps are positive displacement (or fixed displacement). In other words, they pump a constant amount of fluid for each revolution. Some gear pumps are interchangeable and function both as a motor and a pump.

The petrochemical industry uses gear pumps to move: diesel oil, pitch, lube oil, crude oil and other fluids. The chemical industry also uses them for materials such as: plastics, acids, sodium silicate, mixed chemicals and other media. Finally, these pumps are also used to transport: ink, paint, resins and adhesives and in the food industry.

Mathematical calculations are key to any type of hydraulic motor or pump design, but are especially interesting in the gerotor design. The inner rotor has N teeth, where N > 2.  The outer rotor must have N + 1 teeth (= one more tooth than the inner rotor) in order for the design to work.