CENTRIFUGAL GEAR PUMP FOR SUPPLYING LIQUIDS

Abstract

The utility model relates to pump engineering and can be used in various industries for pumping liquids. The technical result consists of high reliability, wear resistance, and stability of performance under load. A centrifugal gear pump comprises a pump casing with inlet and outlet ports and a spacer, an impeller, a drive shaft, a cover, and a gearbox housing. A first-stage gear is fixed to the drive shaft and connected to an intermediate gear shaft via a gear transmission, which is connected to a second-stage gear shaft via a keyed connection, configured to transmit torque to a driven gear shaft. The driven gear shaft is configured to transmit torque to the impeller via the keyed connection. The pump casing, gearbox cover, pump spacer, impeller, and gearbox housing are made of cast iron VCh40.

Description

[0001] The utility model relates to the field of pump engineering and can be used in various fields of industry for pumping liquids.

[0002] The closest technical equivalent is a fire pump (RU Patent 201646, published December 24, 2020, Bulletin No. 36), comprising a housing with a turbine-type impeller mounted on a drive shaft. According to the utility model, the drive shaft is rotated via a gearbox. An additional impeller, designed as an accelerator impeller, is mounted on the drive shaft in front of the impeller. A fixed leveling impeller is mounted on the inner part of the housing. The housing and impellers are made of bronze or aluminum, which is a disadvantage of the device due to its low reliability and wear resistance.

[0003] The technical result achieved by the claimed utility model is high reliability, wear resistance and stability of characteristics under load.

[0004] The technical result is achieved in that the centrifugal gear pump comprises a pump body with inlet and outlet pipes and a spacer, an impeller, a drive shaft, a cover and a gear housing, wherein a first-stage gear is fixed on the drive shaft, connected to an intermediate gear shaft by means of a gear transmission, which is connected to a second-stage gear by means of a keyed connection, configured to transmit torque to a driven gear shaft, wherein the driven gear shaft is configured to transmit torque to the impeller through a keyed connection, wherein the pump body, gear cover, pump spacer, impeller and gear housing are made of cast iron VCh40.

[0005] This centrifugal gear pump is designed for pumping large volumes of clean water (from reservoirs, pits, and cisterns) in areas without power. It is connected to the tractor's power take-off shaft. It is used for irrigation, drainage, field water supply, firefighting, and other agricultural and municipal applications.

[0006] The utility model is illustrated by drawings, which depict:

[0007] Fig. 1 - rear view of the pump,

[0008] Fig. 2 - side view of the pump in section,

[0009] Fig. 3 - side view of the pump,

[0010] Fig. 4 - front view of the pump,

[0011] where 1 is the gearbox housing, 2 is the gearbox cover, 3 is the pump spacer, 4 is the impeller, 5 is the pump housing, 6 is the drive shaft, 7 is the gear of stage No. 1, 8 is the intermediate gear shaft, 9 is the gear of stage No. 2, 10 is the driven gear shaft, 11-12 are the seal, 13-14 is the bearing, 15-16 is the key, 17 is the mechanical end seal.

[0012] The centrifugal gear pump consists of a pump and a gearbox. The pump includes a pump body 5, a gearbox cover 2, a gearbox body 1, a pump spacer 3, a working wheel 4, a gear of stage No. 1 (first stage) 7, an intermediate pinion shaft 8, a gear of stage No. 2 (second stage) 9, a driven pinion shaft 10, a drive shaft 6, a mechanical seal 17, single-row radial ball bearings 13, 14, seals 11, 12 and keys 15, 16.

[0013] The pump components are connected by keyed connections and interference fits. Interference fits are used where the shaft and bearing meet, while keyed connections are used to connect the drive shafts to the gears, transmitting torque between the shaft and the gear.

[0014] The pump housing (5) is a hydraulic chamber. It forms the working cavity, directs fluid flow from the inlet to the outlet, converts kinetic energy into pressure, and serves as the mounting base for all other components. The housing is a cast spiral chamber ("volute"). The axial inlet is located in the center, and the radial outlet is directed to the side. The housing has mounting feet for secure attachment to the tractor or trailer frame.

[0015] Impeller 4 provides direct contact with the fluid, transferring rotational kinetic energy to it. It uses a closed-type impeller with two discs and blades between them, providing high efficiency. The blades are curved backward to ensure a stable pressure characteristic. The impeller has a reinforced hub for greater torque transmission (thickened wall, large radius of curvature at the hub-disc transition (120°)).

[0016] Drive shaft (pump shaft) 6 transmits high torque from the PTO gearbox to the impeller. The drive shaft is a cylindrical shaft with a keyway for securing the first-stage gear 7, which is connected via a gear transmission to the intermediate gear shaft 8, which is connected via a keyway to the second-stage gear 9, which transmits torque to the driven gear shaft 10 and, via a keyway, the torque is transmitted to the impeller 4. On the gearbox side, the drive shaft has a flange or splined connection. Bearings 13 and 14 are mounted on the ends of the intermediate gear shaft 8 and the driven gear shaft 10.

[0017] The gearbox coordinates the tractor's PTO speed (540 or 1000 rpm) with the optimal pump speed (500-600 rpm). The gearbox can increase or decrease the speed and includes a pump on / off switch. The gearbox features an enclosed gear housing, an input shaft (drive shaft 6) with a towbar (quick-release coupling), and an output shaft (driven shaft-gear 10).

[0018] Shaft mechanical seal 17 seals the shaft where it exits the pump casing, preventing fluid leakage. The shaft seal is a dual mechanical seal—two friction pairs operating in series. This provides "double protection" and increased reliability, as leakage is unacceptable in the field. A cavity can be provided between the seals to supply clean water for flushing.

[0019] This pump is a self-contained, powerful and reliable solution for applications requiring high performance in the field.

[0020] The pump body, gearbox cover, pump spacer, impeller, and gearbox housing are made of VCh40 cast iron. The choice of impeller material is a compromise between operating conditions and budget. Cast iron impellers are preferable to aluminum ones in applications requiring high reliability, wear resistance, and consistent performance under load.

[0021] The cast iron impeller offers excellent mechanical strength and abrasion resistance, making it ideal for applications containing abrasive particles (sand, sludge). Cast iron also exhibits high resistance to water and mildly aggressive environments, with a low corrosion rate. Graphite inclusions in the cast iron structure (grade HF) impart high damping capacity; the impeller dampens vibration, reducing noise and bearing loads. The cast iron impeller has excellent casting properties (flowability, mold filling), allowing for the creation of complex flow path geometries with high efficiency. In case of wear (for example, graphite leaching), restoration is possible by welding or machining. Cast iron is inexpensive to produce, making it cost-effective for most industrial pumps. Due to its structure and graphite, cast iron performs better under compression and absorbs peak loads without disrupting the crystal lattice.

[0022] The pump's impellers are paired with sealing rings. Cast iron has antifriction properties (itself a lubricant due to its graphite). This means that if the cast iron impeller accidentally touches the housing ("gap seal"), it will grind in rather than scuff.

[0023] The device uses seals 2.1-38x68x10 and 2.2-20x40-2 (GOST 8752-79), bearings 107 and 204 (GOST 8338-75), keys 2-10x8x16, 5x5x18, 6x6x20 (GOST 23360-78).

[0024] The device operates as follows.

[0025] The pump operates when the tractor is stationary. It is used to transport water from one place to another by tractor. Rotation from the tractor's PTO shaft is transmitted via the drive shaft (cardan) and gearbox to the impeller shaft. The impeller blades throw the liquid away from the center, creating centrifugal force that is converted into pressure at the pump outlet. The impeller is made of cast iron, which makes it superior to aluminum impellers used on competing pumps. Graphite inclusions in the cast iron structure (grade VCh) impart high damping capacity. The impeller dampens vibration, reducing noise and bearing load. Accidental contact with the pump casing prevents scoring of the pump casing or the impeller itself. Such contact results in the grinding of the pump's working parts.It's also worth noting that connecting a pump to a tractor via a cardan shaft is more cost-effective and technologically efficient than using hydraulic motors, as in the field it's preferable to use equipment with a simpler design that can be relied upon in any conditions.

Claims

A centrifugal gear pump comprising a pump body with inlet and outlet pipes and a spacer, an impeller, a drive shaft, characterized in that it also comprises a cover and a gearbox body, wherein a first-stage gear is fixed on the drive shaft, connected to an intermediate gear shaft by means of a gear transmission, which is connected to a second-stage gear shaft by means of a keyed connection, configured to transmit torque to a driven gear shaft, wherein the driven gear shaft is configured to transmit torque to the impeller through a keyed connection, wherein the pump body, gearbox cover, pump spacer, impeller, and gearbox body are made of cast iron ВЧ40.

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