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Gear Hydraulic Pump

The main advantages of gear pumps are simple structure, small size, light weight, good manufacturability, low price, strong self-priming ability, insensitive to oil pollution, large speed range, convenient maintenance, and reliable operation. Low-pressure gear pumps are widely used in low-pressure (under 25×105pa) hydraulic systems, such as machine tools and various oil supplement, lubrication and cooling devices. After taking certain measures in the structure of the gear pump, higher working pressure can also be achieved. The medium pressure gear pump is mainly used in the hydraulic system of the machine tool steel rolling equipment. Medium and high pressure and high pressure gear pumps are mainly used in agricultural and forestry machinery, construction machinery, ship machinery and aviation technology.


Like gear pumps, gear hydraulic motors have poor sealing and low volumetric efficiency, so the input oil pressure cannot be too high, and therefore can not produce large torque, and the speed and torque are pulsating with gear meshing . Gear hydraulic motors are mostly used in hydraulic systems with high speed and low torque. Gear pumps can generally be used directly as hydraulic motors, that is, both gear pumps and gear hydraulic motors are reversible.

Classification of gear pumps: Gear pumps work on the principle of gear meshing. According to different forms of meshing, they are divided into external gear pumps and internal gear pumps.


The structure of the gear pump consists of a pair of gears with exactly the same geometric parameters (tooth width is B, tooth number is z), pump body, front and rear cover plates, long and short shafts.


The working principle of the gear pump: two meshing gear teeth divide the enclosed volume surrounded by the pump body, front and rear cover plates and gears into two parts. The side airtight volume increases, and oil is sucked through the oil suction port.

Applicable occasions and categories of hydraulic gear pumps


The hydraulic gear pump is suitable for transportation of fuel oil, gasoline and diesel oil, mechanical lubricating oil, and other raw material oil substances with wettability and similar characteristics that have a temperature of ≤170°C and a viscosity of less than 100mm²/s. This type of pump is general Used in places such as crude oil, chemical plants, machinery automation, etc.


There are two types of hydraulic gear pumps: external gear and internal gear. The former is simple in structure, low in price, and widely used; the latter is complicated in production and less selection, but because of its light weight, lighter weight, uniform total flow, high efficiency, and long service life, it is suitable for some volume regulations Compact, lighter net weight equipment (such as airports). In order to improve the uniformity and reliability of the total flow of the pump, helical gears or herringbone gears can be selected, and the structure type can be made into a single-pole pump, a double-pole pump or a double-connected pump.


Compared with axial plunger pumps and gear pumps, hydraulic gear pumps have lower efficiency, and the oil removal aspect ratio generally does not exceed 500mm. Because of low efficiency, low working pressure, and low total flow, it is often used as an auxiliary hydraulic oil pump in a simple hydraulic transmission system with medium speed and low interaction force. It can be used in general engineering machinery and equipment, mining equipment, agricultural machinery and CNC lathes and other manufacturing industries.

Select the specific operation of the gear pump


According to the hydraulic gear pump motor selection standard and the basic motor selection standard, the specific steps are as follows:


1. According to the equipment layout, geomorphic standards, water level standards, and operating standards, clearly select vertical, column and other forms (pipeline, deep submersible, liquid, non-clogging sewage pump, self-priming, transmission gear Formula, etc.) hydraulic gear pump.


2. Determine the cold water hydraulic gear pump, the boiling water hydraulic gear pump or the oil hydraulic gear pump, the chemical plant hydraulic gear pump or the anti-corrosion hydraulic gear pump or the residue hydraulic gear pump according to the characteristics of the liquid material, or choose the non-clogging sewage pump hydraulic gear pump .


For hydraulic gear pumps installed in explosion areas, the relative explosion-proof motors should be selected according to the level of the explosion area.


3. According to the total flow size, clarify whether to choose a single-suction hydraulic gear pump or a double-suction hydraulic gear pump; according to the height of the pump head, choose a single-pole hydraulic gear pump or a multi-level hydraulic gear pump, high-speed rotating hydraulic gear pump or a low-speed hydraulic gear pump ( Central air-conditioning hydraulic gear pump), multi-stage hydraulic gear pumps have lower efficiency than single-pole hydraulic gear pumps. If both single-pole hydraulic gear pumps and multi-stage hydraulic gear pumps are available, the first single-pole hydraulic gear pump is used.


4. Clarify the model and specifications of the hydraulic gear pump, and clarify which series of hydraulic gear pumps are used, and then use a larger total flow rate (when there is no larger total flow rate, generally 1.1 times the normal total flow rate can be used as a comparison Large total flow), take the basic parameters of the two characteristics of the pump head after increasing the capacity by 5%-10%, and clarify the model specifications on the type spectrum or series product characteristic curve.


5. After the gear pump model is clarified, the water hydraulic gear pump or the water-like hydraulic gear pump for the physical substance of the transport material should be listed in the relevant product catalog or sample version, and the correction should be carried out according to the specification table or characteristic curve diagram of the model. , To see if all normal working parts fall in the priority working area of ​​the hydraulic gear pump.


6. For liquid hydraulic gear pumps with a transportation viscosity exceeding 20mm²/s (or relative density exceeding 1000kg/m3), the characteristic curve of the hydraulic gear pump tested with water must be calculated as the characteristic of the viscosity (or the relative density) The graph, it is very important to carry out careful calculation or comparison of the suction energy and the input output power.


7. Clarify the number and reserve rate of hydraulic gear pumps: Generally, only one hydraulic gear pump is used for all normal operating hydraulic gear pumps. Because a large hydraulic gear pump and two small hydraulic gear pumps in series work are very, (referring to water pumps) The head and total flow are the same), the large hydraulic gear pump is more efficient than the small hydraulic gear pump, so from the perspective of environmental protection and energy saving, I would rather choose a large hydraulic gear pump instead of two small hydraulic gear pumps, but in the following situations, It can be considered that two hydraulic gear pumps cooperate in series:


The total flow is quite large, and a hydraulic gear pump cannot reach this total flow.


For large and medium-sized hydraulic gear pumps that must have a 50% reserve rate, two smaller hydraulic gear pumps can be changed to work, and two are reserved (a total of three).


For some large and medium-sized hydraulic gear pumps, hydraulic gear pumps with 70% of the total flow rate can be used for actual operation. There is no need to reserve hydraulic gear pumps. When one hydraulic gear pump is repaired, the other hydraulic gear pump is still responsible for manufacturing 70%. % Of transportation.


For hydraulic gear pumps that need 24 hours of continuous operation, three hydraulic gear pumps should be reserved, one for operation, one reserved, and one for maintenance.


8. Under normal circumstances, customers can submit their “basic standards for selecting hydraulic gear pumps”, and the pump manufacturer will give the motor selection or strongly recommend better hydraulic gear pump products. If the Planning Institute clearly stated the model and specifications of the hydraulic gear pump when designing the equipment and equipment, it should be equipped according to the regulations of the Planning Institute.