FR2560289A1 - Mixed ''normally aspirated/supercharged'' inlet system for an internal combustion engine - Google Patents

Abstract

According to the invention, this mixed inlet system comprises two inlet circuits arranged in parallel on the inlet of the engine 1: - a first circuit intended for operation in the normally aspirated phase and composed of a duct 6 leading to the inlet manifold 2 of the engine and incorporating a non-return device 7; and - a second circuit intended for operation in the supercharged phase and composed of a duct 8, 9, 11 leading to the inlet manifold 2 of the engine and successively incorporating a butterfly valve 12, a compressor 5 and a heat exchanger 10. Application especially to supercharged internal combustion engines to simultaneously improve the dynamic response to acceleration and the efficiency.

Description

"ATMOSPHERIC-SUPERCHARGED" MIXED SUPPLY SYSTEM
FOR INTERNAL COMBUSTION ENGINE.

The present invention relates to a mixed "atmospheric-supercharged" supply system intended to improve the acceleration behavior of an internal combustion engine supercharged by a turbocharger which receives its drive energy from the exhaust gases of this engine.

A defect commonly advanced against such an engine lies in its reduced ability to accelerate from a low speed or from a partial load in comparison with the power obtained from the supercharging.

Indeed, a supercharging system during operation in the atmospheric phase is perfectly useless; it also generates a loss of efficiency, either by increasing the exhaust back pressure for a turbocharger, or by mechanical energy absorption for a driven compressor.

In the particular case of turbocharged engines, there are solutions tending to reduce, under partial load, the exhaust back pressure: for example, it is possible to divert part of the gases directly to the exhaust without passing through the turbine Unfortunately, by this type of embodiment, the standby speed of the turbocharger is inevitably reduced, which leads to a rapid deterioration of the dynamic response during acceleration, this property is therefore rightly often criticized, even in the absence of a device. bypass.

The invention proposes to remedy these drawbacks in a particularly simple and effective manner.

Actually, it relates to a mixed "atmospheric-supercharged" supply system which, according to a feature of the invention, comprises two supply circuits arranged in parallel on the intake of the turbo-supercharged engine - a first circuit intended during operation
atmospheric phase and consisting of a conduit
leading to the intake manifold through
a non-return device; and - a second circuit intended for phase operation
supercharged and constituted by a conduit leading to the
intake manifold and incorporating successively
a butterfly valve, a compressor and an exchanger
heat.

According to another feature of the invention, this butterfly valve closing the second atmospheric phase supply circuit is actuated by a pneumatic cylinder controlled by a pressure valve, a non-return valve and a socket on the intake manifold. These features make it possible to simultaneously improve the dynamic acceleration response and the efficiency of the turbocharged engine.

Other features and advantages of the invention will appear more clearly on reading the following description of a preferred embodiment, given by way of nonlimiting example and with reference to the appended drawings in which - Figure 1 represents a schematic view of a sys
mixed atmosphere-supercharged feeder
for an internal combustion engine, conforming to
the invention; and - Figure 2 represents a variation curve of the
control pressure of a butterfly valve in operation
pressure at the intake manifold of the
wetness, this butterfly valve integrated into the system
illustrated in Figure 1 ensuring the passage of a
operation in atmospheric phase to that in
supercharged phase and vice versa.

A turbo-charged ignition engine 1 shown in FIG. 1 comprises an intake manifold 2 and an exhaust manifold 3. It is equipped with a supercharging system comprising a turbine 4 and a compressor 5.

According to the invention, the mixed supply system developed is based on the use of two supply circuits arranged in parallel on the engine intake. The first circuit has a conduit 6 connected to the intake manifold 2 by means of a non-return device 7. The second circuit comprises three portions of conduit 8, 9 and 11 separated by the compressor 5 and a heat exchanger 10, and a butterfly valve 12.This butterfly valve, which is capable of 1-closing this second circuit, is actuated by a pneumatic valve 13 com by a manomic valve 14, a non-return valve 15 and not taken 16 on the intake manifold 2.

This power system operates as follows, with reference to Figures 1 and 2
In the atmospheric phase, the second supply circuit which provides the supercharging, is closed by the butterfly valve 12 preferably arranged upstream of the compressor 5.

In the vicinity of the full atmospheric load, and at a level determined by the setting of the pneumatic cylinder 13 in relation to the control device 14, 15, the opening of the butterfly valve 12 activates the supercharging; the first circuit intended for operation in the atmospheric phase is then eliminated by the non-return device 7.

The pneumatic device 14, 15, 16 emits a control signal from the pneumatic cylinder 13, the evolution of which as a function of the pressure prevailing in the intake manifold 2 is represented by the curve in FIG. 2 where, depending on the direction of evolution of the engine load - ab represents the intake pressure difference at
manifold 2 for the same control pressure of
the butterfly valve 12; and - ac represents the control pressure difference of the
butterfly valve 12 for the same inlet pressure
to collector 2.

These differences in pressure ab and ac observed between an evolution at increasing load and an evolution at decreasing load, are equal to the setting pressure at the opening of the manometric valve 14. They well reflect the operating stability of the motor 1 thus supplied , to all diets.

Line p separates the curve of FIG. 2 into two distinct parts which correspond to two phases of engine operation
Below this line is the part relating to an atmospheric phase supply with the butterfly valve 12 closed.

Above this line is the part relating to a supercharged phase supply with the butterfly valve 12 open.

The advantage of this mixed supply technique lies in the limitation of the resistive torque of the compressor wheel 5; in fact, this torque is proportional to the mass flow rate and depends only to a much lesser extent on the pressure ratio.

As the outflow from the engine remains about the same during the atmospheric phase, at constant speed and load, the rotation speed of the turbocharger increases very significantly, which has two advantageous consequences - the dynamic response is improved; - the engine efficiency increases due to the dimi
exhaust back pressure by
increased permeability of the turbine 4.

Claims (2)

1. "Atmospheric-supercharged" mixed supply system for an internal combustion engine (1) equipped with a turbocharger (4, 5) driven by the exhaust gases, characterized in that it comprises two supply circuits arranged in parallel on the engine intake - a first circuit intended for operation in  atmospheric phase and consisting of a conduit (6)  leading to the engine intake manifold (2) by  through a non-return device (7); and - a second circuit intended for phase operation  supercharged and constituted by a conduit (8, 9, 11)  leading to the engine intake manifold (2) and  successively incorporating a butterfly valve (12),  a compressor (5) and a heat exchanger (10). 2. mixed supply system according to claim 1, characterized in that this butterfly valve (12) closing the second circuit in atmospheric phase, is actuated by a pneumatic cylinder (13) controlled by a pressure valve (14), a non-return valve (15) and a socket (16) on the intake manifold (2).