The present invention relates to exhaust systems, and more particularly to exhaust scavenging systems for reciprocating engines.
Internal combustion reciprocating engines by the nature of their design produce large amounts of unused energy that is expelled in the form of the waste gases. Harnessing this energy and putting it to use would thereby increase the overall efficiency of the engine.
Reciprocating internal combustion engines by design are generally restricted to a very short period of time for cylinder evacuation. After initial blow down of the cylinder the engine then consumes a portion of its generated energy to push the burn gases out of the cylinder as the piston moves up. By lowering the pressure ahead of the gases they move out of the cylinder more easily and reduce the pumping energy required by the engine. The design of this device uses each exhaust pulse to create a low pressure zone ahead of the next pulse which effectively reduces the pressure at the exhaust port.
The internal combustion engine acts fundamentally as a mechanical pump. It draws in air and pushes the air out, any reduction in resistance of air flow directly reduces the amount energy required to pump the air. In operation this invention uses the kinetic energy of the blow down pulse to create a low pressure zone for the next blow down cycle causing a reduction in the required pumping force.
A full evacuation of the combustion cylinder is desired to reduce contamination of the incoming fuel air charge. Creating a lower pressure at the exhaust port reduces the level of contamination remaining in the chamber.
A common practice is to use tubular headers with a collector, “Y” and “X” pipes to produce this effect on high revving, high performance engines. These systems tend to be expensive, work only at higher RPM, are difficult to package in normal applications, and only produce 1 stage of scavenging.
As can be seen, there is a need for an improved exhaust gas scavenging system to harness the kinetic and pressure energy available in the exhaust flow to power an induction pump with no moving parts. This use of waste energy increases total performance and engine energy efficiency.
In one aspect of the present invention, an exhaust gas scavenging apparatus for an internal combustion engine, includes a plurality of sealed interconnected chambers, each chamber having at least one outer sidewall and an end wall to define a cavity therein. A plurality of in line tubes pass through the plurality of sealed chambers and are interconnected along a length of the exhaust gas scavenging apparatus. The plurality of in line tubes are configured to receive an exhaust gas flow from the exhaust of an internal combustion engine and communicate the exhaust gas through the plurality of sealed chambers. Each of the plurality of in line tubes have a sidewall, an inlet and an outlet, the inlet having a larger diameter than the outlet, wherein the sidewall converges inwardly along a length of the tube to define a Venturi constriction proximal to the outlet. The outlet of a preceding in line tube is received within the inlet of a subsequent lined tube.
The exhaust gas scavenging apparatus may also include a Venturi opening formed between the outlet of the preceding in line tube and the inlet of a subsequent in line tube. The Venturi opening may be formed within each of the plurality of sealed chambers. The end walls of the chamber are sealed around the sidewall of the in line tubes, preferably around an intermediate portion of each in line tube. In some embodiments, the Venturi opening is located at an intermediate position within the plurality of sealed chambers.
In other embodiments, an exhaust gas scavenging apparatus for an internal combustion engine includes a plurality of sealed interconnected chambers, each having at least one outer sidewall and an end wall to define a cavity therein. An in line tube is carried through the plurality of sealed chambers, with the in line tube configured to receive an exhaust gas flow from an exhaust of the internal combustion engine and communicate the exhaust gas flow through the plurality of sealed chambers. A Venturi constriction is defined in the in line tube in each of the plurality of sealed interconnected chambers and a Venturi opening is defined at an end of the Venturi constriction. The Venturi opening is configured to communicate an exhaust gas pulse between the cavity and an interior of the in line tube.
In some embodiments a single tube with a plurality of perforations is used to create the venturi for each of the sealed chambers. The perforated tube is aligned within each sealed chamber so that a series of sidewall perforations aligned to the downstream most portion of each sealed chamber. The perforations in this embodiment represent the Venturi openings. The chamber side wall is sealed to the next chamber and the end wall of each chamber is sealed around the sidewall of the perforated tube creating a cavity. The Venturi opening may also be located at an intermediate position within the plurality of sealed chambers.
These and other features, aspects and advantages of the present invention will become better understood with reference to the following drawings, description and claims.
The following detailed description is of the best currently contemplated modes of carrying out exemplary embodiments of the invention. The description is not to be taken in a limiting sense, but is made merely for the purpose of illustrating the general principles of the invention, since the scope of the invention is best defined by the appended claims.
Broadly, embodiments of the present invention provide an exhaust system with a series of chambers designed to actively lower the exhaust gas back pressure in an internal combustion engine. The device uses the waste energy from the exhaust system in the form of both the Venturi principle and the amplification of a pulse wave effect. The scavenging system uses a series of in-line tubes or a single tube with perforations, passing through multiple sealed chambers using the Venturi effect to lower the pressure in each chamber.
Each exhaust pulse, when passing through the device, is able to multiply the intensity of its own trailing low pressure and reduce the pressure ahead of a subsequent exhaust pressure pulse produced by the engine. The leading pulse is coupled to the trailing pulse by the low pressure zone between the two pulses. The inertia from the leading pulse enables it to continue its direction of flow while the trailing pulse is accelerated or drawn into the low pressure zone between the two pulses. The net effect is that every pulse that passes through the system lowers the resistance for the subsequent pulse until equilibrium is achieved. The resulting action of the exhaust scavenging device is to increased engine performance through increased cylinder exhaust scavenging, reduction of exhaust gas back pressure and increased engine volumetric efficiency.
As seen in reference to
The in line tubes 1 have an inlet 9 and an outlet 10, wherein the inlet 9 has a larger diameter that than the outlet. The sidewalls of the in line tubes 1 converge inwardly along a length of the tubes 1 from the inlet 9 to the outlet 10 to form a Venturi constriction at a junction between the respective tube elements 1. The in line tubes 1 are interconnected such that the outlet 9 of a preceding in line tube 1 is received within the inlet 10 of a subsequent lined tube 1. A Venturi opening 3 is formed at a gap between the smaller diameter outlet 9 of the preceding tube 1 and the larger diameter inlet 10 of the subsequent in line tube 1. The end walls 8 of each sealed chamber 2 are sealed around a circumference of the sidewall of the in-line tubes 1.
As seen in reference to
Each chamber 2, 18 of the device is able to create a drop in pressure 5 as an exhaust blow down pulse 4 passes through and a volume of trapped air contained within the plurality of chambers 2, 18 is drawn out of the sealed chambers 2 via the Venturi inlets 3, 13. By using multiple chambers 2, 18 in sequence, a greater reduction in pressure is achieved. Given that the blow down pulse 4 has both mass and kinetic energy, it will continue to travel down the exhaust system while pulling against the low pressure it has generated behind it. The next blow down pulse 4 generated by the engine will attempt to accelerate into the low pressure area ahead of it, thereby increasing its speed. The increase in speed also increases the Venturi effect on each of the chambers 2, 18 as this secondary pulse passes through causing a greater drop in pressure 5.
The system of the present invention installs in-line with an exhaust system as a muffler type device, which can work as low as idle speeds on multiple cylinder engines and may have multiple stages of scavenging in a small relatively inexpensive package.
As seen in reference to
It should be understood, of course, that the foregoing relates to exemplary embodiments of the invention and that modifications may be made without departing from the spirit and scope of the invention as set forth in the following claims.
This application claims the benefit of priority of U.S. provisional application No. 62/397,114, filed Sep. 20, 2016, the contents of which are herein incorporated by reference.
Number | Date | Country | |
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62397114 | Sep 2016 | US |