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Fabrication of Motorized Tri-Cylinder Air Compressor

Published on Jan 24, 2017


The compressor is mechanical equipment which is used to increase the pressure with the help of the piston. Need to improve the performance of compressor by several methods. The main aim of the project is to make tri-cylinder air compressor to generate large amount of air with less power and low vibration. In tri cylinder air compressor the three cylinders are kept at 120 degree to each other. The three cylinders are placed radically and equally apart such that the cylinder opening tends to meet on a common triangular compression chamber. The three pistons are made to compress air simultaneously on to common tri angular chamber over shorter stroke and the isothermal efficiency will be better than single cylinder with one piston.

The motor is connected to the chain drive to drive the three crank shaft which is used to move the piston. If space is smaller the pressure will be more and bigger the lower. If compressor is made to work at 1400 rpm air taken will be147.18 × 1400 = 206052 litters at 7 atmospheres pressure .The advantage with triangular compressor will be low vibration, smaller unit giving more output and so cheaper to make, ideal for air compressor is Air conditioning and Refrigeration, Vacuum pumps and general purpose usage.


The compressor is mechanical equipment which is used to increase the pressure with the help of the piston.

1.1. Types of air compressor

According to the design and principle of operation

1. Reciprocating compressor

2. Rotary screw compressor

3. Turbo compressor

1.2 Positive displacement

Positive-displacement air compressors are the type of compressor executed by forcing air into a chamber whose volume is decreased to compress the air. Piston-type air compressors use this principle by pumping air into an air chamber through the use of the same motion of pistons. This type of compressor uses one-way valves to guide air into a chamber, where the air is compressed. Rotary screw compressors also utilizespositive-displacement compression by matching two helical screws that, when turned, guide air into a chamber, whose volume is increased as the screws turn. Vane compressors use a slotted rotor with varied blade placement to guide air into a chamber and compress the volume. This type of Compressor delivers a fixed volume of air at high pressures. The types of positive displacement compressors include piston compressors and rotary screw compressors.

1.3 Negative displacement

Negative-displacement air compressors consist of the centrifugal compressors. This type of compressor use centrifugal force generated by a spinning impeller to accelerate and then decelerate captured air, which pressurizes the air.

1.4 Cooling

The result ofadiabatic heating, air compressors require some type of disposing of waste heat for the better performance. Generally the cooling is some form of air- or water-cooling, although some (particularly rotary type) compressors may be cooled by oil (that is then in turn air- or water-cooled).and the atmospheric changes also included during cooling of compressors.

1.5 Tri-cylinder air compressor

We need to improve the performance of compressor by several methods. Such as designs shape and construction are known and screw type compressor is the latest design as on date. The power required to compressor air to a known pressure is given in the attached tables. One cubic root of air equals approximately 28 litters its volume we brought of a novel idea to design the triangular compressor as per the attached sketches or diagrams with this.

2. Plan of experiments

2.1 Electrical connection

The electrical power supply must be connected to the motor through starter. Start the unit momentarily and observe the direction of rotating the rotor. The direction should be clockwise. If the direction of rotation is not correct change the direction by interchanging the two places in the starter.

2.2 Adjusting belt tension

The chain tension between the motor and Crankshaft flywheel must be correctly adjusted with proper tension. Otherwise the Compressor will not run of the required speed

2.3 Starting procedure

The following are to be checked before starting the unit.

Check the oil level in the oil indicator if the level is the oil level indicator if the level is below the minimum mark, add fresh oil to the correct grade.

Check the chain tension 

Check the suction pipe air filler

Check that the unit rotates freely by hard and that there is no mechanical obstructions 

Start the unit and allow it to run for a few minutes

2.4 Checks during operation

Check whether the running sound is normal 

Check the pressure developed by opening manometer safety device

If all the above preliminary checks are found satisfactory then the unit may be put to regular use.

Figures and equations

Fabrication of Motorized Tri-Cylinder

Working principle

This triangular air compressor with common compression chamber consists of three cylinders placed at 120 to each other cylinder. The main aim if this compressor is to generate large amount of air compared with existing compressor with less power input and with low vibration. For this compressor contain three cylinders having their own piston, connecting rod, crank shaft and their drive. Chain drive was preferred to overcome slipping. When the motor drives the crank shaft all the three piston will move in phase from BDC to TDC, when the piston reaching TDC compression takes place and discharge is done and when reaches the BDC suction condition are obtained and suction takes place.

Comparison of conventional one with ours

We know of several types of compressors made in many renowned factories at Coimbatore for various applications piston type, screwed type value type etc., but three pistons compressing air into a common compression chamber is not known to be a existing and so we decide to make this novel design to prove its superiority to others in cost and performance. Any new product must be novel and useful it must be superior is performance, reliable and dependable compared to known models.

The cost of making must be comparatively low and in the market it should be capable of competating similar products, is every way, color appearance, value etc. Range must be based on from perspective users and customers. However first working model is only to prove superiority as per maker’s claims. When it is compared with the existing ones it has very lesser vibration and lesser oil consumption and it is more reliable than the connectional ones because of having less vibration and also it is a Novel-idea.

Result and discussion

The performance of the compressor was found to be satisfactory and the output of the compressor is continuous it is up to the level expected. Further improvements can be done on the radial compressor.


1) Best suitable for low pressure application.

2) Less weight compared to other compressor.

3) Production cost is low.

4) Higher efficiency because of less power required.

5) High Durability.

6) Compactness of the compressor saves utilization space.

7) Easy to use and portable.


1) Used in laboratories and pharmaceuticals.

2) Used for fabrication of plastic structure with hot gas.

3) Used for best control fumigation service.

4) Used for air agitation of photo film processing tanks, electroplating bath and in chemical plants.

5) Used for cooling electronic circuits.

6) Used for inflating tyres and air mattresses.

7) Used for light duty spray painting.

8) Used to operate air driven hand tools such s Die-Polishers, Die-Grinders etc.,

9) Used in bore wells to deliver water from the well

Future scope

The tri cylinder air compressor with common compression chamber can be improved in following areas,

1) Lubrication method to be improved to reduce wear and tear.

2) Inter cooling can be used to reduce the work done when multistage compression is used.

3) Pressure rise can be increased by reducing the clearance volume.

4) The production cost can be reduced by casting the cylinder and the head assembly into a single piece.


The design and fabrication of triangular air compressor in the common compression chamber have been successfully completed and over all assembly of the compressor is drawn in this report. The performance of the compressor was found to be satisfactory and the output of the compressor is continuous it is up to the level expected. Further improvements can be done on the radial compressor as dealt in the previous chapter.



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[3] HuibinLianga and Xuehua Lib of Integrated Monitoring System Design of Hybrid Aircompressors,Procedia Engineering, 15 (2011) 938 – 943.

[4] HuibinLianga and XuehuaLib,Applications of Frequency Conversion Technology in AircompressorUnits Control System,Procedia Engineering, 15 (2011) 944 – 948.

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