GB2130643A

GB2130643A - I.C. engine intake and exhaust systems

Info

Publication number: GB2130643A
Application number: GB08322201A
Authority: GB
Inventors: Klaus-Peter Bessing
Original assignee: Dr Ing HCF Porsche AG
Current assignee: Dr Ing HCF Porsche AG
Priority date: 1982-09-18
Filing date: 1983-08-18
Publication date: 1984-06-06
Also published as: GB2130643B; IT1197677B; FR2538450A1; GB8322201D0; DE3234728A1; IT8348689A0

Abstract

To prevent noise creating oscillations in a pipe 5 which at times is closed, e.g. closed by a valve 6 where the pipe forms a turbine by pass or closed by an intake or exhaust valve where the pipe (16, Fig. 2) forms the intake or exhaust pipe of a temporarily inoperative cylinder, a device 7, which provides a higher resistance to reverse rather than normal direction flow, is installed in the pipe adjacent its connection to another part of the system, e.g. the turbine outlet pipe 3' or a manifold (17, Fig. 2). The device 7 may be a check valve or a chamber (8, Fig. 3) including an ejector (12, 15) which operates as such only in the normal flow direction. <IMAGE>

Description

SPECIFICATION A pipe system in a reciprocating piston internal combustion engine The present invention relates to a pipe system at the cylinders of a reciprocating piston internal combustion engine which is traversed by gases and includes a first line continuously traversed by gases during the operation of the internal combustion engine and a second line connected thereto which is traversed by gases only for periods of time.

Such pipe installations which may be exhaust gas lines or air intake lines, are excited by pressure pulsations of the gas flow at their natural or resonant frequency into vibrations with high amplitude. If both lines are traversed by gas, these resonant rises are damped by the gas flow itself.

If, in contradistinction thereto, the gas passage through the line is closed off, then the standing gas column in this line is excited at its resonant or natural frequency by the pressure pulsations of the other line traversed by the gases and loud humming and buzzing noises result.

These effects can be observed in exhaust gas systems of internal combustion engine with exhaust gas controlled turbochargers, in the bypass line of which is installed a bypass valve.

With a closed bypass valve, i.e. at the lower to the middle rotational speed range of the internal combustion engine, a standing gas column is therefore present in the pipe line between the bypass valve and discharge side of the exhaust gas turbine into which enter pressure shocks of the exhaust gas line and cause resonant vibrations. Also in internal combustion engines with cylinder cut-out, these effects occur in the exhaust gas system, and with a valve cut-out additionally also in the suction system since also in these cases the line system not traversed by gases is excited into vibrations or oscillations with strong noise formation by gas pulsations of the other line system.

The object of the present invention is to effect a noise damping in such pipe systems.

The underlying problems are solved in accordance with the present invention by installing a flow resistance into the line not traversed by gases near the connection with the line traversed by gases, which flow resistance offers a considerably higher resistance to a back flow of the gases than to a forward flow of the gases. If such a flow resistance is inserted into the bypass line of an exhaust turbine, then the penetration of a pressure pulsation and the noisy sympathetic vibrations of this line can be effectively reduced.If in an internal combustion engine with cylinder turn-off or cut-out by rendering the inlet valve inoperable, these flow resistances are installed into the individual suction pipes of the turned-off cylinders, pressure shocks can also penetrate from the suction manifold to the inlet valves, however, their vibrational return flows are impaired by the installed flow resistances and a noise damping is thus achieved.

In the accompanying drawings: Figure 1 isa schematic view of an internal combustion engine with an exhaust gas installation and turbocharger in accordance with the present invention; Figure 2 is a schematic view of an air intake installation of an internal combustion engine with cylinder turn-off or cut-out in accordance with the present invention; and Figure 3 is a schematic cross-sectional view through a flow resistance in accordance with the present invention.

Referring now to the drawings and more particularly to Figure 1, four exhaust gas pipes 2 are connected to an internal combustion engine 1, which are combined into a common exhaust gas pipe 3, into which is installed an exhaust gas turbine 4 of a turbocharger. A bypass valve 6 is installed in a bypass pipe 5 to the exhaust gas pipe 3, which bypass valve is closed in the lower to middle rotational speed range of the internal combustion engine. A flow resistance 7 is inserted into the bypass pipe 5 near the connecting place 3' with the exhaust gas pipe 3, which is iilustrated on a larger scale in Figure 3.

The flow resistance 7 shown in Figure 3 consists of a cylindrical container 8 having a first pipe section extending in a sealed manner through one end wall 9 thereof. The first pipe section 10 is provided with several radial openings 11 and terminates in a nozzle shaped orifice 12 which is directed toward a second coaxial pipe section 13 that extends in a sealed manner through the oppositely disposed end wall 14. The forwardly flowing gas indicated by the arrow can thus flow into the container 8, on the one hand, through the openings 11 and, on the other, out of the orifice 12 into the pipe section 13, whereby the gas in the container 8 is sucked into the gap 1 5 between the orifice 12 and the second pipe section 13 as a result of the nozzle-shaped construction of the orifice 12. A small flow resistance thus opposes the forward flow of the gases.A back flow, in constrast, is strongly impeded. For the gas leaving the pipe section 1 3 flows in large part into the container 8 from which it can enter into the pipe section 10 only through the narrow radial passage openings 11. Only a small portion of the gas can enter directly into the pipe section 10 from the pipe section 1 3 by way of the orifice 12.

Such flow resistances 7 are installed according to Figure 2 into two individual suction pipes 16 of an air intake installation which lead from a common suction pipe or suction manifold 1 7 to the cylinders of an internal combustion engine 1 8 which are adapted to be cut-out or turned-off. The other two individual suction pipes 19, starting from the suction manifold 1 7 form together with the manifold 17, the first line continuously traversed by gases, whereas the turned-off individual suction pipes 1 6 represent the second line traversed by gases only intermittently.

In lieu of the flow resistances 7 shown schematically in Figure 3, also a check valve may be used. However, a pre-requisite therefore is that the moving valve body has such a slight mass and is equipped with such a strong spring that the natural or resonant frequency resulting from these values lies above the pulsation frequency of the exhaust gas respectively of the suction air. For only in that case valve body can follow the rapid pulsations and is able to close the valve before the momentarily cut-off or temporarily turned-off second line is excited into noisy vibrations.

Claims

1. A pipe system at the cylinders of a reciprocating piston internal combustion engine which is traversed by gases and includes a first line continuously traversed during the operation of the internal combustion engine and a second line connected with the first line and traversed only during periods of time, wherein the second line contains a flow resistance near the connection with the first line which opposes a significantly higher resistance to a back flow than to a forward flow.

2. A pipe system according to claim 1, wherein the first line is an exhaust gas pipe into which is inserted an exhaust gas turbine and the second line is a bypass pipe to the first line, which is adapted to be closed by a bypass valve 6 installed into same.

3. A pipe system according to claim 1, wherein the first line is a suction manifold of an air intake installation with several individual pipes constantly traversed by air, which are connected thereto and lead to the cylinders, whereas the second line consists of a group of individual suction pipes which are coordinated to temporarily turned off cylinders.

4. A pipe system according to claim 1, wherein the first line includes a group of exhaust gas pipes which are constantly traversed by exhaust gases whereas the second line consists of a group of exhaust gas pipes which are coordinated to temporarily turned off cylinders.

5. A pipe system according to any one of claims 1 to 4, wherein the flow resistance includes a closed off container into which extends from one side a first pipe section in sealed relationship, the first pipe section being provided within the area of the container with a plurality of radial holes and a nozzle shaped outlet orifice, and a second pipe section arranged through the oppositely disposed end wall of the container coaxially and spaced from the first pipe section.

6. A pipe system according to any one of claims 1 to 4, wherein the flow resistance is a check valve operating nearly inertialess whose natural frequency is higher than the pulsation frequency of the gas flow conducted through the pipe system.

7. A pipe system substantially as described with reference to, and as illustrated in, Figure 1 or Figure 2 of the accompanying drawings.