Turbo Charger and Compressor - Part Four

Turbo charger
Turbo charger

Compressor

A brief history of the compressor

If you are wondering who made the first compressor, the answer is Gotlib Daimler (yes, yes, Daimler Benz or more recently Daimler Chrysler). This German engineer patented a pump that allowed for increased compression of the mixture inside the cylinder chamber. He didn't call the system a "turbocharger," but what he described in the document was a birth description of the first car compressor. Gotlib designed his automotive compressor in a similar fashion to a two-rotor industrial "air displacement" that was invented and patented 40 years earlier by Francis Ruts of Indiana, USA in 1860. The same principle is still used today, and immediately afterwards the German engineer Krigar invented an air pump that is still used today in the so-called. Lysholm compressors. Shortly thereafter, compressors found great use during World War I in aircraft engines and after the war. Mercedes In 1921, he achieved great success by starting serial production of a car with a turbocharged engine. In the racing scene, cars that used compressors were very successful. In 1924, compressors appeared in the Indy 500, and racing cars around the world used a new technique to increase engine power. In the mid-30s, Robert Paxton McCullough did McCulloch Engineering, which is a specialized company that made compressors used on engines in American passenger cars, and that is the moment when turbochargers are becoming what they are today. After World War II, compressors brought new life to sports competitions around the world. Alfa Romeo and BRM used turbochargers on their Grand Prix cars, which were shortly afterwards banned. In the 50s, McCulloch founded Pakston Engineering as a separate company that took over the development of compressors on its own and aimed to make a cheap turbo compressor that would be easily marketed widely. After spending $ 700000 and two years of testing, the VS57 compressor model was ready to go public in 1953. Initially, it only worked on Ford cars manufactured in 1950 - 1953, and in 1954 began selling kits for almost all commercial models of cars that had 6 or 8 cylinders. Following the great success of that VS57, Pakston Engineering has continued to make a number of new models.

Paxton VS 57 Turbo Compressor

Paxton VS 57 Turbo Compressor

Air Compression Modes

Roots Compressor - Blower
The Roots compressor was initially conceived as a ventilation device in industrial buildings. It consists of two blades that rotate in the opposite direction and practically "bite" the air from the inlet and expel it to the outlet. This compressor is of "fixed volume" ie. It drives a fixed amount of air per unit of time, so it is independent of engine speed, ie. it is very good for use at low to medium speeds, making it ideal for use on trucks and trucks. Such compressors are self-lubricating, and they are also the simplest of construction, so their price is moderate and they are very reliable. For this reason, this type of compressor is used by GM, Ford, Mercedes and Toyota. The only downside to this type of compressor is that it generates large amounts of heat. One of the reasons is that this compressor practically only accelerates the air, but the compression itself takes place in the intake branch of the engine ie. outside the compressor.

Roots compressor

Roots compressor

Two-screw compressor
At first glance, this kind of compressor does not differ too much from the roots, both externally and internally. The two approaches are similar, but there are significant differences. The central part of this compressor are two rotors, ie. "Screws" that rotate towards each other to draw in air from the inlet to the compressor, and by turning the screws, the air moves to its outlet and compresses at the same time. In this case, the air compression takes place inside the compressor itself, so this design generates less heat than the roots design, and it works even better at low and medium rpm, so this compressor is also used in trucks and other trucks. Unlike the roots of the compressor where the blades touch each other with this type of compressor there is no physical contact between the parts ie. screws and therefore there is no wear and tear on any element. Therefore, the reliability of this type is very high. The only drawback of this design is that this compressor always works (and back or brake) so at these times it practically uses the power of the engine and minimizes it so that the air that is compressed would be expelled by a valve bypassing the intake manifold.

Two-screw compressor

Two-screw compressor

 

Two-screw compressor system

Two-screw compressor system

Centrifugal compressor

Turbocharger with impeller

Turbocharger with impeller

Although this type of compressor is based on much newer technology than the previous two, it is the first successfully implemented compressor in the automotive industry. Unlike previous compressors, this one does not have a "fixed volume". does not run the same

of air in a unit of time. It functions as a very fast propeller ie. impeller (propeller having a rotating function) by sucking air into the middle of the compressor and ejecting it at the circumference of the high-speed impeller (over 40000 rpm). The air under centrifugal force moves along the circumference of the impeller ellipse to the circumference where that air is directed to the outlet, thereby compressing the air by means of a venturi. The air further moves toward the outlet along the narrowing funnel, thereby reducing the air velocity and further increasing the pressure. This design has several very important features. It is very simple and therefore reliable, then produces very little heat because the compression takes place inside the compressor, while being very compact and versatile as it can be "uncoupled" and thus allow the engine to suck air directly through the compressor without compressor operation. It is also very thermally efficient, ie. produces compressed air that has the lowest temperature of all three designs presented. The only downside is that it takes a high impeller speed to get the compressor to start producing enough compressed air so it is very inefficient at low RPM, but its efficiency rises with RPM. Such compressors are not only lubricating but also need to be connected to the engine oil flow system, though some manufacturers make such compressors that have only lubrication capability.

Impeller layout

Impeller layout


G Charger - Emergence and development

Considering the Vokswagen's Polo G40, Golf 2 G60 and Corrado G60 models were very popular and kind of icons from the early 90's, here's a brief description of how the G-Charger works.

At a time when it was the fashion of all car makers to install a turbocharger, the leading man of the then Volkswagen Development Department took over the Frenchman L. Creux's basic idea of ​​a coil-shaped charger. He saw the possibilities offered by such a charger in comparison to the then alternative - turbochargers. The first attempts at a spiral charger promised solutions to the demands of VW bosses: spontaneous turn-down response, power available throughout the rev range, reduced noise, ideal for mass production, usable for different engine concepts.

In 1987, the small-scale production of the G-Charger engine began in the 40-hp VW Polo GT G115. The name G40 is derived from the shape i, because the length of the coil in the "accelerating auger" (similar to G) has a width of 40 mm in the working part of the charger.

1988 was followed by the installation of a larger G60 charger with a larger "accelerating auger" (60 mm wide working area) in a 1,8 hp VW Corrado 160. In the same year, a VW Golf Rallye with G60 engine and all-wheel drive was produced in approximately 5000 units, primarily for type-approval for rally racing, but due to restrictions required on intake, official racing was stopped and so free space for Audi Quattro. In 1989, the G60 was incorporated into the VW Passat GT Syncro, and a year later into the VW Golf GTI G60.

The most powerful engine powered by the G-Charger is manufactured by VW Motorsport, a 1,8 16v G60 with 210 hp and 250 Nm of torque at 5000 rpm, and comes in VW Golf II versions with a fifth door.

Even today, the G-Charger technique resists the tooth of time, although Volkswagen has long since stopped producing it. The main reasons for this are the relatively high cost of production and the not-so-negligible failure rate (vehicle power is often overstated by drivers). What's more interesting is that the G charger is followed by a rather bad reputation as a perishable device, and as German VW sites say the culprit is a poorly designed shaft that swivels the charger's belt and recommends the installation of another that solves virtually any problem.

G Charger - Specifications

The G60 is a mechanically driven charger named after the G-shape, and 60 indicates the width of the helical propellers, expressed in mm. In a spiral compressor, the intake air from the engine passes through a snail-like housing, where it compresses up to 0,7 bar. This compressor, which consumes up to 18 HP, is powered by a toothed belt. Its great advantage is its power along all speeds. And the weaknesses? When the engine reaches 5800 rpm, the small coil in the compressor spins at 11 000 rpm, and this is the boundary area where critical vibrations in the compressor begin, and this can be fatal to the whole engine. Otherwise, for G60 engines, the maximum torque is at 5600 rpm.

Turbo or compressor

This is one of the more common questions and, unfortunately, does not have an easy answer. To be more precise, the answer is simple, but it reads "it depends." This section of the text will outline the advantages and disadvantages of the compressor and help you to understand in which cases it is better to apply the appropriate system.

Similarities
Both compressors and turbochargers are systems that allow the intake air to be pressurized and thus their goal is to compress the air into the engine cylinders as much as the atmospheric pressure normally allows. The advantage is that the engine will then be able to burn more fuel in a single combustion cycle, leading to an increase in power. For this reason, turbo compressors and turbochargers allow 40 - 100% increase in power (depending on the air pressure) than atmospheric engines of the same volume.

Price
The price of the compressor and turbocharger for the same engine are practically the same, so the price does not play any role in choosing either of these two systems.

Team
The downside to lag is one of the biggest advantages of a turbocharger over a turbocharger. The turbochargers are powered by exhaust gases, so this delay occurs until the impeller is rotated to a speed that allows adequate air compression. The turbochargers are powered by a strap, which, on the other hand, is hooked to the crankshaft, thus practically operating at the lowest RPM.

Efficiency 
This is the biggest advantage of a turbocharger. Turbochargers are generally more economical because they are powered by exhaust gas, which is to say, free of charge. they serve nothing while the compressor uses the crankshaft power, thereby reducing the power available to start the car. However, turbochargers are not fully efficient because turning the turbine blades creates a sub-pressure on the exhaust manifold so that the engine has some resistance when it exhausts.

Heat 
As the turbocharger is mounted on an exhaust branch that is always very hot, only the turbine housing is heated, and thus the turbocharging air is further heated, which negatively affects the compressed air density, so an intercooler is often used to cool that air, and this complicates the installation of the system. For compressors, a centrifugal compressor generates very cold compressed air, so there is no need to mount an intercooler for pressures below 0,8 bar, while when using a root compressor, the compressed air has a much higher temperature, so it is necessary to use the intercooler even at low pressures.

A stroke of power
As turbochargers have lag (lag) there is a so-called a power stroke when the westgate opens i.e. when the turbocharger runs out. This impact is very damaging to the car and especially to the engine mounts, suspension and steering system and can make the car difficult to manage. Back pressure Turbochargers, by mounting on the exhaust branch, produce parasitic back pressure within the branch itself, and thus the engine consumes more energy to expel the exhaust gas for as long as necessary to overcome that parasitic pressure. This pressure reduces the efficiency of the turbocharger.

Open
Turbochargers are generally quieter than the compressor, and the position of the turbine on the exhaust can only reduce the amount of noise generated by the engine, thus silencing the engine. Turbo compressors have a specific sound, especially centrifugal ones, and they can be very loud (of course most drivers just love this sound).

Reliability 
Compressors are generally far more reliable than turbochargers. When the car (and engine) is shut off, the hot engine and exhaust can damage the oil inside the turbocharger that lubricates the bearings with high temperature. Additionally, high turbine speeds (up to 150000 rpm) can lead to turbine bearing problems and thus shorten the life of the turbocharger.

Maximum power 
Turbochargers have gained notoriety because they have the ability to spin very quickly, generating fantastically high compression pressures (over 2 bar) and of course producing far more power than turbochargers.

Possibility to improve the performance of the turbochargers / compressors themselves - tuning
Turbochargers, due to their complexity and dependence on exhaust gas, are notoriously difficult to modify. Compressors, on the other hand, are lighter in this regard and additionally require only minor interventions on fuel injection and ignition systems.

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