WO2000065210A1

WO2000065210A1 - A storage prebooster to improve the responsiveness of turbocharged internal combustion engines

Info

Publication number: WO2000065210A1
Application number: PCT/AU1999/000316
Authority: WO
Inventors: John Ypsilantis
Original assignee: Individual
Current assignee: Individual
Priority date: 1999-04-28
Filing date: 1999-04-28
Publication date: 2000-11-02
Anticipated expiration: 2001-10-28
Also published as: AU3400199A

Abstract

The disclosed invention is a storage prebooster which overcomes the characteristic delay in response in turbocharged internal combustion engines when the throttle is opened. The prebooster is used to provide immediate supercharging until the turbocharger begins to develop effective boost. The prebooster is recharged at this point in readiness for future throttle changes. The prebooster can supercharge the engine via a direct connection to the inlet manifold, or it may be used to preemptively accelerate the turbocharger itself in response to the opening of the throttle. A combination of the two preboosting techniques may also be used. The storage prebooster comprises a storage cylinder, a valve for the initial charge and for the re-charging the cylinder, a variable outlet valve and a controller for governing the rate of discharge or preboost during throttle setting changes.

Description

"A Storage Prebooster to Improve the Responsiveness of Turbocharged Internal Combustion Engines"

Turbocharging is a relatively inexpensive technique for increasing the power output of an internal combustion engine. A small turbine, which is driven by exhaust gases -from the engine, is used to compress the air entering the cylinder, which in turn increases the energy liberated by the fuel during combustion. This increases the mechanical output of the engine with respect to an identical unit which would be charged at normal atmospheric pressure.

Supercharged engines exhibit fuel consumption comparable to a normally aspirated engine when they are operated with small to moderate engine speeds, but they develop power and torque outputs comparable to larger capacity engines when operating at higher speed. This is often a desirable feature for passenger vehicles, where good fuel economy is desirable in city and suburban traffic, and higher performance is required in freeway conditions.

There is a major drawback associated with turbocharging. The inlet pressure cannot rise until the engine develops an increase in exhaust pressure, which in turn accelerates the turbine. There exists a finite time between the opening of the throttle and the response of the engine. This delay is often termed turbo lag. Alternative supercharging schemes which employ direct mechanical compression are less prone to such effects. However, the major drawback with these schemes is that they are generally much more complex and costly in relation to turbocharging.

The invention described in this specification is a technique which provides an initial or pre-boost to the inlet pressure when the engine's throttle is opened. This preboost is supplied via a reservoir of compressed air, and a controlled release valve. The preboost provides an immediate response in engine output for the interval of time where the turbocharger increases its speed. The prebooster then enters a recharging cycle, in readiness for subsequent throttle changes.

Figure 1 (a) is a diagrammatic representation of a conventional turbocharged internal combustion engine. The air intake (i) is made via a turbine (ii) which is driven by exhaust flow from the engine (iv) as the engine vents to the atmosphere (v). As the exhaust pressure increases, the turbine accelerates and in turn it increases the inlet manifold pressure (iii), which provides a higher-than-atmospheric charge to the cylinders for their inlet cycles.

Figure 1 (b) shows the same engine with a storage prebooster. This comprises a storage cylinder (v), an inlet valve (iv) and an outlet valve (vi). The storage cylinder is charged from the inlet manifold whenever the inlet pressure is higher than that in the cylinder itself. Changes in the engine's throttle setting result in the outlet valve opening appropriately. For example, the outlet valve's position may be proportional to the rate of change in the position of the throttle, and as such may be operated via a simple PD controller.

The additional resulting flow of gas accelerates the turbocharger faster than would be the case if it relied on exhaust flow alone. This causes the inlet pressure to rise more rapidly than would be the case otherwise, i.e., the supercharging effects occur sooner than would be the case for the engine in Figure 1 (a).

The delivery of the preboost in Figure 1 (a) may also be achieved by releasing pressurised fluid into an ancillary drive chamber for the turbocharger. For example, the storage reservoir and the turbocharger's ancillary drive chamber may be part of a closed circuit comprising pressurised oil. In a passenger vehicle which also comprises power assisted steering, the existing oil pressurising system may be used to drive the turbocharger's preboost. Alternatively, the oil reservoir may be pressurised by the introduction of exhaust gas or compressed air from the inlet as before. A variation for the scheme depicted in Figure 1 (b) is to charge the storage cylinder with exhaust gas from the outlet manifold, rather than with compressed air from the inlet manifold. Yet another variation is for the prebooster to drive the turbocharger separately, thus avoiding any interference with exhaust gas flow.

Figure 1 (c) shows another variation, where the inlet valve may be operated at the same time as the outlet valve. This provides a direct preboost to the engine, rather than solely via the turbocharger. This may be done in isolation, or in combination with the preboost flow to the turbocharger when air is used to charge the storage cylinder.

The above techniques may also be applied to other engine types, e.g., gas turbines, jet engines, although the utility in such applications may be limited, owing to the manner in which such engines are normally used. For example, turbines are generally operated at fairly constant throttle settings, as opposed to constantly varying settings as is the case for road vehicles.

Claims

"A Storage Prebooster to Improve the Responsiveness of Turbocharged Internal Combustion Engines"The claims defining the invention are as follows:

1. -Any method for improving the responsiveness of a turbocharged internal combustion engine, which comprises the preboosting of the inlet manifold pressure via momentary controlled injection of pressurised gas or fluid into the main or an auxiliary drive chamber of the turbocharger from a storage reservoir.

2. Any method for improving the responsiveness of a turbocharged internal combustion engine, which comprises the preboosting of the inlet manifold pressure via momentary controlled release of compressed air from a storage reservoir directly to the inlet manifold of the engine.

3. Any method for improving the responsiveness of supercharged internal combustion or turbine engines which involves momentary controlled injection of pressurised fluid, compressed combustion-supporting or other gas from a storage reservoir into an ancillary chamber of the supercharger or directly into the engine itself.

SUBST-ITUTE SHEET (Rule 26) (RO/AU)