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Internal gear pump
An internal gear pump is a type of positive displacement pump used for the transportation of fluids. It operates on the principle of internal gearing, where two gears—one with external teeth and the other with internal teeth—mesh with each other. The gears rotate within a pump casing, creating a sealed chamber between the gear teeth and the pump casing. As the gears rotate, fluid is trapped in the spaces between the gear teeth and the pump casing, and it is carried from the inlet to the outlet of the pump.
Here are some key features and characteristics of internal gear pumps:
Positive Displacement: Internal gear pumps are classified as positive displacement pumps because they displace a fixed volume of fluid with each revolution of the gears. This makes them suitable for applications where a constant and precise flow is required.
Internal Gearing: The pump typically consists of an outer gear with external teeth and an inner gear with internal teeth. The gears rotate in opposite directions, creating a pumping action that moves the fluid from the suction side to the discharge side.
Sealed Chambers: The meshing of the gear teeth and the pump casing forms sealed chambers that contain the fluid. This design results in efficient pumping and helps maintain a consistent flow.
Reversible Operation: Internal gear pumps can often operate in both directions, allowing for reversible fluid flow. This feature can be advantageous in certain applications.
Viscosity Range: Internal gear pumps are capable of handling a wide range of viscosities, making them suitable for pumping fluids with varying thickness, from thin liquids to highly viscous substances.
Relatively Low Noise Level: Compared to some other types of pumps, internal gear pumps often produce relatively low noise levels during operation.
Principle of Internal Gear Pump
When internal meshing gear pair is used along with seperator to increase pressure of oil, it is known as internal gear pump.
An internal gear pump is a type of positive displacement pump that consists of two gears—an outer gear (the rotor) and an inner gear (the idler). The gears mesh together and rotate in opposite directions within a pump casing, creating a sealed chamber between the teeth of the gears and the pump casing. This sealed chamber moves the fluid from the pump’s inlet to its outlet.
Construction of Internal Gear Pump
It consists of following main parts
1) Internal tooth gear : The internet spur gear is connected to the motor shaft.
2) External tooth gear : It is mounted eccentrically with respect to internal tooth gear. It is driven by internal tooth gear.
3) Crescent shaped separator : Between the above two gears, on one side there is a crescent shaped spacer is provided. It is stationary part of the housing around which oil is carried.
4) Inlet and outlet port : The inlet and outlet ports are located in the casing for suction and delivery of oil.
5) Shaft: The shaft connects the rotor to the external power source, enabling the rotation of the gears.
Functioning of Internal Gear Pump
Inlet Stage: As the rotor rotates, the teeth of the rotor and idler come into contact at the pump’s inlet side, creating a suction or low-pressure area. This causes fluid to be drawn into the pump through the inlet port.
Meshing Stage: The teeth of the rotor and idler gears mesh together, trapping the fluid within the sealed chamber formed by the gears and the pump casing.
Transport Stage: As the gears continue to rotate, the fluid is carried around the sealed chamber from the inlet to the outlet side of the pump. The volume of the sealed chamber decreases, causing the fluid to be displaced and pressurized.
Outlet Stage: The pressurized fluid is forced out through the outlet port as the teeth of the gears disengage at the pump’s outlet side.
Leakage Stage: Internal gear pumps can experience internal leakage due to the close tolerances between the gears and the pump casing. This leakage is typically small and is managed by the pump’s design and clearances.
Internal gear pumps are known for their efficiency, reliability, and ability to handle a wide range of viscosities. They are suitable for both low-viscosity and high-viscosity fluids, making them versatile for various industrial applications.
Working of Internal Gear Pump
When motor shaft rotates, it will rotate the internal gear and it drives the external gear.
It effects a fluid fight seal at the meshing point of the teeth. The teeth wich are unmeshing at the inlet port creates partial vaccum and suction of oil occurs.
Oil is get trapped between internal and external gear teeth and both side of the crescent shaped spacer.
Meshing of gear teeth reduces the volume in the high pressure cavity near the outlet port and discharge high pressure oil from the outlet port.
The internal gear pumps are very efficient and produces less noise.
The volumetric efficiency is about 95% and overall efficiency 85-90% .
What are the main features and benefits of an internal gear pump?
Internal gear pumps are a type of positive displacement pump that is widely used for various applications. They consist of one or more internal gears that rotate within an external gear. Here are some of the main features and benefits of internal gear pumps:
Internal gear pumps are positive displacement pumps, meaning they move a fixed amount of fluid with each revolution. This makes them suitable for applications requiring a consistent and precise flow rate.
High Viscosity Fluids:
Internal gear pumps are capable of handling high-viscosity fluids, such as oils and polymers, making them suitable for a wide range of industrial applications.
Internal gear pumps are often self-priming, which means they can create a suction to draw fluid into the pump without the need for external priming. This feature simplifies the installation and operation of the pump.
The direction of flow in an internal gear pump can be easily reversed by changing the direction of rotation. This makes them versatile for applications where bidirectional flow is required.
Internal gear pumps typically have a compact and simple design, making them easy to install and maintain. The compact size allows for easy integration into various systems and applications with limited space.
Low Pulsation and Noise:
Internal gear pumps generally produce low pulsation and noise levels compared to some other types of positive displacement pumps. This is advantageous in applications where smooth and quiet operation is important.
Internal gear pumps can be highly efficient, especially when operating at their design point. Their design minimizes internal leakage, contributing to overall efficiency.
Wide Range of Applications:
These pumps are used in various industries, including automotive, chemical processing, food and beverage, oil and gas, and more. They are versatile and can handle different types of fluids across a broad range of temperatures and pressures.
Due to their simple design and manufacturing, internal gear pumps are often cost-effective both in terms of initial purchase and ongoing maintenance costs.
Materials Used For Internal Gear Pump
Internal gear pumps are commonly used in various industrial applications for pumping fluids. The materials used in the construction of internal gear pumps depend on the specific requirements of the application, the type of fluid being pumped, and environmental factors.
However, some common materials used for internal gear pumps include:
Cast Iron: Cast iron is a common material for internal gear pump casings and housings. It provides strength and durability, making it suitable for handling a variety of fluids. It is also resistant to wear and corrosion.
Stainless Steel: Stainless steel is often used for internal components such as gears and shafts. It offers good corrosion resistance and is suitable for applications where the pumped fluid may be corrosive.
Bronze: Bronze is another material used for gears and other components in internal gear pumps. It provides good wear resistance and is often used in applications where the pump handles abrasive fluids.
Aluminum: Aluminum is lightweight and corrosion-resistant. It is sometimes used for pump casings in applications where weight is a critical factor, such as in portable pump systems.
Carbon Steel: Carbon steel is used in some internal gear pumps for its strength and durability. It may be coated or treated to enhance corrosion resistance.
Polymer/Plastic: Some internal gear pumps use polymer or plastic materials for certain components. These materials may include PTFE (polytetrafluoroethylene) or other thermoplastics, especially for applications where chemical resistance is crucial.
Ceramics: In specific applications, ceramic materials may be used for components that require high wear resistance and tolerance to extreme conditions.
Advantages and Disadvantages of Internal Gear Pump
Internal gear pumps are widely used in various industries for fluid transfer and pumping applications. Like any other technology, they have their own set of advantages and disadvantages. Here are some advantages and disadvantages of internal gear pumps:
High Efficiency: Internal gear pumps are known for their high volumetric efficiency, meaning they can move a large volume of fluid with minimal energy losses. This makes them energy-efficient and cost-effective in the long run.
Wide Range of Viscosity: Internal gear pumps can handle a wide range of fluid viscosities, from low-viscosity liquids to highly viscous fluids. This versatility makes them suitable for pumping different types of liquids, including thin oils, fuels, chemicals, and even adhesives.
Self-Priming: Internal gear pumps are self-priming, which means they can draw fluid into the pump and create suction without the need for external priming assistance. This feature simplifies the installation and operation of the pump.
Low Noise and Vibration: Internal gear pumps operate with minimal noise and vibration levels, making them suitable for applications where quiet operation is required, such as in medical equipment or in noise-sensitive environments.
Reversible Flow: Internal gear pumps can provide reversible flow by changing the direction of rotation. This feature allows for versatility in applications that require bidirectional pumping.
Limited Solids Handling: Internal gear pumps are not designed for handling fluids with high solid content. They are more suitable for pumping clean or slightly contaminated fluids. Solids or abrasive particles in the fluid can cause wear and damage to the pump’s internal components.
Sensitivity to Fluid Viscosity Changes: While internal gear pumps can handle a wide range of viscosities, they may experience a decrease in performance when there are significant changes in fluid viscosity. Viscosity changes can affect the pump’s volumetric efficiency and overall pumping capability.
Limited Pressure Capability: Internal gear pumps are typically limited in their maximum pressure capability compared to other pump types, such as centrifugal pumps. If high-pressure pumping is required, additional stages or a different pump design might be necessary.
Internal Leakage: Internal gear pumps can experience internal leakage due to the close tolerances between the gears and the pump casing. This internal leakage can reduce the overall efficiency and require regular maintenance and monitoring to prevent issues.
Complex Design: The internal gear pump design consists of multiple internal components, such as gears, bushings, and shafts. This complexity can make the pump more difficult to manufacture, assemble, and maintain compared to simpler pump designs.
Internal gear pumps find application in various industries and sectors due to their versatile pumping capabilities.
Lubrication Systems: Internal gear pumps are extensively used in machinery and equipment lubrication systems. They can efficiently pump lubricating oils or fluids to ensure smooth operation and minimize wear and friction between moving parts.
Chemical Processing: Internal gear pumps are suitable for handling various chemicals and corrosive fluids. They are used in chemical processing plants for transferring and circulating chemicals, acids, solvents, and other corrosive substances.
Fuel Transfer: Internal gear pumps are commonly employed in fuel transfer applications, such as refueling systems, fuel oil delivery, and bulk fuel transfer. They can handle a wide range of fuels, including gasoline, diesel, biodiesel, and aviation fuel.
Food and Beverage: Internal gear pumps are employed in the food and beverage industry for pumping various liquids, including fruit juices, sauces, chocolate, syrups, and food additives. They are designed to meet sanitary standards and can handle both viscous and non-viscous food products.
Polymer and Plastics: Internal gear pumps are used in polymer processing and plastics manufacturing for pumping polymers, resins, and molten plastics. They provide consistent and reliable flow control, which is crucial for maintaining quality and precision in these processes.
Hydraulic Systems: Internal gear pumps are utilized in hydraulic power units and systems for generating hydraulic pressure. They can provide the necessary flow and pressure for operating hydraulic cylinders, actuators, and motors in various industrial machinery and equipment.
Marine and Offshore Applications: Internal gear pumps are employed in marine and offshore industries for applications such as ballasting, bilge pumping, fuel transfer, and hydraulic power units. They are chosen for their compact size, reliability, and ability to handle marine fuels and fluids.
What is internal gear pump?
When internal meshing gear pair is used along with seperator to increase pressure of oil, it is known as internal gear pump.
How do internal gear pumps operate?
Liquid travels through the pump between the teeth of the “gear-within-a-gear” principle. The crescent shape divides the liquid and acts as a seal between the suction and discharge ports. Intermeshing gears of the idler and rotor form locked pockets for the liquid which assures volume control.
What is pressure range of internal gear pump?
Internal gear pump nominal pressure range is 315 bar, and 350 bar in intermittent operationand, speed range for all sizes is up to3,000 rpm.
What causes internal gear pump leakage?
Gear pump will not assemble properly. Lubrication of gear pump bearings requires flow from areas of high pressure to low pressure to establish a correct hydrodynamic bearing.
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