WO2006112801A1

WO2006112801A1 - Exhaust pipe with a damping chamber

Info

Publication number: WO2006112801A1
Application number: PCT/SI2006/000018
Authority: WO
Inventors: Igor Akrapovic
Original assignee: Igor Akrapovic
Priority date: 2005-04-22
Filing date: 2006-04-21
Publication date: 2006-10-26
Also published as: SI22014A

Abstract

An exhaust pipe with a damping chamber is used as a constituent or independent part of exhaust systems for internal combustion engines. It is used to provide additional sound damping of internal combustion engines, to increase the power and torque of internal combustion engines and to increase the linearity of curves of power and torque subject to the number of revolutions of an internal combustion engine. It consists of a basic straight or bent pipe of a round or oval cross-section (5) connected to a damping chamber (6) via two or several straight or bent pipes having a round or oval cross- section (7, 8). The damping chamber consists of a straight or bent pipe of a round or oval cross-section, the ends of which are hermetically closed.

Description

Exhaust Pipe with a Damping Chamber

The object of the present invention is an exhaust pipe with a damping chamber, or better a pipe having a round cross-section connected to a pipe having a round cross- section, the ends of which are closed, via two or several pipes having a round cross- section. The pipe of a round cross-section with the closed ends represents a damping chamber.

The exhaust pipe with a damping chamber is used as a constituent part or as an independent part of exhaust systems of internal combustion engines.

The technical nature of operation of internal combustion engines causes the engines to be very noisy. The noise is reduced by various damping elements or silencers, the disadvantage of which is that they reduce power and torque of the engine. The power and torque of the engine are reduced due to disproportionate flow of exhaust gases discharged into the exhaust system during individual exhaust cycles of the engine. Each individual flow of exhaust gases discharged into the exhaust system from the combustion area in the engine in one exhaust cycle of the engine is considered as one pulse. It is of advantage if the frequency of pulses of exhaust gases as much as possible overlaps with the frequency of pulses of the charging cycle of the engine, in which a mixture of fuel and oxygen is delivered to the combustion area. A problem arises when engine revolutions are changed, because a change of the revolutions also changes the frequency of pulses of both the exhaust and charging cycles, which can consequently lead to a shift in frequency. An inadequate shift in frequency between the pulses of the exhaust and the charging cycle can cause a decrease of power and torque of the engine. Moreover, it is desired that internal combustion engines have as linear curves of power and torque of the engine as possible subject to the engine revolution, because this contributes to the operating performance of the engine. The linearity of the curve of the power and torque of the engine subject to the engine revolutions depends on the engine structure and on the structure of the exhaust system and is very heavily achieved with additional elements at a later stage. A technical problem solved by the invention is extremely good additional sound damping of internal combustion engines, increase of power and torque of internal combustion engines and the linear shape of the curves of power and engine torque subject to the internal combustion engines revolution.

Significant additional sound damping of internal combustion engines with a damping chamber is proved when measuring the noise, because the noise decreases by an average of 2 dB in comparison with the noise of engines with an exhaust system without a damping chamber. An increase of power and torque of the engine as well as higher linearity of the curves of power and torque of the engines subject to the engine revolutions is evident when the power and torque of the engines are measured, which is evident from the diagram of the curves of power and torque of the engines subject to the engine revolutions, which are plotted in measurements. The height of the curve indicating the increase of power subject to the engine revolutions with an exhaust system with a damping chamber (1 ) is by 2 to 3% higher on the average than the curve of the increase of power subject to the engine revolutions with an exhaust system without a damping chamber (2), which represents an average of 2 to 3% higher power of an engine with an exhaust system with a damping chamber in the entire range of revolutions. Moreover, the height of the curve indicating the torque subject to the engine revolutions with an exhaust system (3) with a damping chamber is by 2 to 3% higher on the average than the curve indicating the torque subject to the engine revolutions with an exhaust system (4) without a damping chamber, which represents an average of 2 to 3% higher torque of an engine with an exhaust system with a damping chamber in the entire range of revolutions. The shape of curves (1 ) and (2) of increase of power and torque subject to the revolutions of an engine with an exhaust system with a damping chamber is more linear in comparison with the curves (2) and (4) of increase of power and torque subject to the number of revolutions of an engine with an exhaust system without a damping chamber.

There are no known solutions of exhaust pipes with a damping chamber in the same construction concept. The invention consists of a basic straight or bent pipe of a round or oval cross-section

(5) connected to a damping chamber (6) via two or several straight or bent pipes having a round or oval cross-section (7, 8). The damping chamber consists of a straight or bent pipe of a round or oval cross-section, the ends of which are hermetically closed. The basic pipe (5) of the invention represents the basic pipe of the entire exhaust system. The diameters of the basic pipe (5), connecting pipes (7, 8) and the damping chamber

(6) are optional and can be in various mutual ratios. The length of the basic pipe (5) and the damping chamber (6) is optional. The number of connecting pipes (3, 4) is two or more. The internal diameter of the pipes (7, 8) connecting the basic pipe and the damping chamber is the same or larger than the diameter of the bores on the basic pipe and the damping chamber. The connecting spot of the connecting pipes (7, 8) with the basic pipe (5) and the damping chamber (6) is optional and adapted to the configuration of the exhaust system. If a bent basic pipe (5) and a bent damping chamber (6) are used, the angle of bending and the radius of bending are optional.

The invention operates in a way that the damping chamber (5) and the connections (7, 8) between the damping chamber (5) and the basic pipe (6) diminish the influence of the frequency shift of pulses of the exhaust and charging cycles, which can arise when the engine revolutions are changed. An individual pulse discharged into the exhaust system is divided in a primary and secondary pulse at the first connection (7). The primary pulse travels along the basic pipe (5), the secondary pulse travels through the damping chamber (6) and the second connection (8). When the engine revolutions are changed, a frequency shift is noted in the secondary pulse. When the secondary pulse is re-joined with the primary pulse, which is normally already the pulse of the next exhaust cycle, it comes to mutual dependence and adjusting of differences. As a consequence there is a small phase shift of pulses of the exhaust and charging cycles and more constant flows of exhaust gases through the exhaust system.

Figure 1 shows a diagram of the curve of power of an engine with an exhaust system with a damping chamber (1 ) and of the curve of power of an engine with an exhaust system without a damping chamber (2). Figure 2 shows a diagram of the curve of torque of an engine with an exhaust system with a damping chamber (3) and of the curve of the torque of an engine with an exhaust system without a damping chamber (4).

Figure 3 shows a 3D model of an exhaust pipe with a damping chamber. The exhaust pipe is shown in the bent variant.

Figure 4 shows a cross-section of an exhaust pipe with a damping chamber. The exhaust pipe is shown in the bent variant.

Figure 5 shows a 3D model of an exhaust pipe with a damping chamber. The exhaust pipe is shown in the straight variant.

Figure 6 shows a cross-section of an exhaust pipe with a damping chamber. The exhaust pipe is shown in the straight variant.

The invention can be used as an independent or constituent part of exhaust systems of internal combustion engines. It can be used in all industrial areas where internal combustion engines are used (car industry, aircraft industry, motorcyclism, ...).

Claims

Patent Claims

1. An exhaust pipe with a damping chamber, characterised in that it provides a significant additional sound damping of internal combustion engines, increases the power and torque of internal combustion engines and increases the linearity of curves of power and torque subject to the number of revolutions of an internal combustion engine.

2. An exhaust pipe with a damping chamber according to claim 1 , characterized in that it consists of a basic straight or bent pipe of a round or oval cross-section (5) connected to a damping chamber (6) via two or several straight or bent pipes having a round or oval cross-section (7, 8), said damping chamber consisting of a straight or bent pipe of a round or oval cross-section, the ends of which are hermetically closed.