Summary of lubrication and maintenance mechanisms commonly used for motors and water pumps

1、 Lubrication mechanism

Lubrication is the addition of lubricant between two friction surfaces in relative motion, forming a lubricating film between the two friction surfaces, separating the dry friction surfaces that were originally in direct contact, and transforming dry friction into friction between lubricant molecules, in order to reduce friction, reduce wear, and extend the service life of mechanical equipment.

1. Lubrication effect

(1) After controlling the lubrication between the friction surfaces, as the lubricant is between the two friction surfaces, the dry friction becomes the friction between the lubricant molecules. Therefore, the friction coefficient and friction resistance between the friction surfaces vary with the lubrication state between the friction surfaces.

(2) The reason why reducing wear and lubrication can reduce wear is because lubrication can reduce friction, minimize friction, and avoid welding and tearing wear on metal surfaces. In addition, the cleaning effect of liquid lubricants is also very effective in preventing wear by cleaning impurities such as dust and metal abrasive particles on the friction surface of machine parts.

(3) During the operation of cooling mechanical equipment, it is necessary to overcome the friction on each friction surface to do work, and all the work consumed in overcoming the friction has been converted into heat. The result is an increase in the temperature of the friction surface, causing thermal deformation of the metal to reach its melting point, causing adhesion on the friction surface. Lubricants are a good heat dissipating agent, which can timely carry heat to the cooling surface to dissipate.

(4) To prevent the friction surface from rusting, various mechanical friction surfaces inevitably come into contact with surrounding media such as air, water droplets, water vapor, corrosive gases and liquids, dust, oxides, etc., causing metal surfaces to rust, corrode, and be damaged. When there is lubricant covering the friction surface, it can prevent corrosion caused by this.

(5) The sealing effect, such as the self sealing effect of lipids, not only prevents the loss of lubricants, but also prevents the invasion of moisture and impurities. The cylinder and piston in the compressor are in a highly sealed state and also have the function of oil. The hydraulic oil used for hydraulic transmission also has sealing properties.

(6) Transmission of power, such as hydraulic transmission

2. The importance of equipment lubrication

Equipment is one of the elements of enterprise production. To maintain the equipment in good technical condition, attention must be paid to its maintenance and proper lubrication during its use. Only in this way can friction be controlled, wear reduced, energy consumption in the transmission mechanism reduced, equipment life extended, equipment damage and failures reduced, and maintenance costs reduced. Therefore, equipment lubrication is directly related to saving energy, materials, and manpower, improving the quality, reliability, lifespan, and safety of mechanical products, and creating more material wealth.

According to a statistic, over one-third of the world's energy is ultimately manifested as frictional losses in various forms during various mechanical energy transfer processes.

3. Reasons for equipment cleaning and oil change

Lubricating oil (grease), due to mechanical friction, generates heat, agitation, and mechanical shear during use, as well as the influence of the surrounding environment, such as the invasion of air, water vapor, dust, metal particles, etc., gradually oxidizes and deteriorates, producing gum, asphaltene, and acidic substances, resulting in reduced performance until it cannot be further used. If used continuously, it will corrode the machine parts, block the oil system, and a large amount of abrasive particles will be brought back into the friction surface, causing pulling grooves and abrasions. So it is very necessary to establish an oil change interval.

2、 Common lubrication methods

1. Manual oiling (grease) lubrication is carried out by the operator regularly using an oil pot or gun to add oil to the oil holes and cups

2. Drip lubrication utilizes oil to drip through a controllable small hole on the drip device under the action of gravity, and to lubricate the lubrication area at regular intervals.

3. Oil rope and oil pad lubrication immerses one end of the oil rope and oil pad into an oil pool, and the other end directly contacts the moving surface in the friction pair, using capillary action to allow oil to enter the friction pair for lubrication.

4. Oil ring or oil chain lubrication refers to the lubrication where the oil ring or oil chain is sleeved on the journal, causing its lower part to be immersed in an oil pool. When the shaft rotates, the friction force drives the oil ring to rotate, thus bringing oil into the bearing for lubrication.

5. The lubrication method of immersing the friction surface into a lubricating oil pool through oil bath or splash lubrication is called oil bath lubrication. Splash lubrication refers to the lubrication method in which the lubricating oil in the oil pool is splashed onto the friction surface by rotating moving parts immersed in the oil pool or by oil throwers, oil throwers, etc. attached to the shaft. The most typical equipment using oil bath and splash lubrication is a sealed gearbox.

6. Forced lubrication forms an oil wedge or film on the friction surface through external pressure oil supply, such as using a lubricating oil pump.

For example:

1. Rolling bearings use oil bath or splash lubrication combined with oil ring lubrication, such as ordinary horizontal centrifugal pumps.

2. The sliding bearing adopts forced lubrication, such as supplying oil through an oil pump.

3. The crankcase adopts oil bath lubrication.

3、 Water pump maintenance mechanism

1. The simple principle of connecting devices for oil level indicators is to maintain a certain liquid level for easy observation, usually designed to maintain a normal liquid level at half to two-thirds of the full height. Structural features, such as glass tubes, openings on the top, side discharge plugs, etc

2. Oil cup, also known as constant oil level oiler. Features: principle of negative pressure liquid column balance, design of inclined surface for discharge outlet, and control of low liquid level.

3. The oil seal is often in the form of a labyrinth or centrifugal. But it is only a dynamic seal, not a static seal, so it does not have absolute sealing conditions, and excessive refueling will overflow.

4. The vent plug is usually located next to the refueling plug to balance the pressure inside and outside the fuel tank, expel excess gas, and prevent dust and other intrusion.

5. The outer shell walls are often made into finned shapes for timely heat dissipation.

6. The water-cooled jacket is mostly finned sleeve type.

7. Fan blade motors are commonly used, and pumps can be used as optional components.

8. Frequently Asked Questions

(1) The oil level is too low, and the oil bath is not sufficient, making it difficult for the oil to reach all the friction surfaces above, resulting in dry wear and burning of the bearings. Generally, the normal oil level should be designed to be between 1/3 and 2/3.

(2) The phenomenon caused by excessive refueling is that the heat dissipation space is small, and the oil is prone to overheating, which first affects the performance of the grease and reduces the lubrication effect. At the same time, under strong agitation, it is easier to dissolve too much gas, resulting in the phenomenon of oil foam (i.e. bubbles in the oil). It disrupts the balance of the oil cup, causing infinite injection to increase and result in a vicious cycle.

(3) The deterioration of oil quality is generally caused by expiration, water ingress, or other impurities leading to emulsification, mixing of different oil products, and so on.