GB2319305A

GB2319305A - Turbocharger with supplementary air drive

Info

Publication number: GB2319305A
Application number: GB9623279A
Authority: GB
Inventors: Philip Gerald Bevan
Original assignee: Individual
Current assignee: Individual
Priority date: 1996-11-08
Filing date: 1996-11-08
Publication date: 1998-05-20
Also published as: GB9623279D0

Abstract

To avoid turbine lag when the throttle 22 of a turbocharged engine is opened, supplementary air is supplied under pressure to nozzles 14, that direct the air onto the rotor of the turbocharger compressor 10, to impart drive thereto until the turbine 12, reaches full operating speed. A vehicle power supply 26, powers a separate compressor 24, that pressurises a reservoir 16, having a pressure sensor 30. A proportionate valve 18, controls flow to the nozzles 14, in response to signals from a throttle responsive switch controller 20, and an engine management system 32.

Description

Turbocharger This invention relates to a turbocharger for an internal combustion engine.

A commonly used turbocharger for internal combustion engines, especially in motor vehicles for example, comprises a compressor shaft driven from a turbine powered by the engine exhaust gases. The compressor delivers compressed air to the engine in order to boost power output.

A well known problem with such turbochargers is turbine lag. Thus, when extra power, especially from idling or near idling speed, is called for by opening of the throttle, as by depression of the accelerator pedal in a motor vehicle, it takes time for the exhaust gases, the flow of which increases due to delivery of extra fuel to the engine, to build up sufficiently to drive the turbine, and thus the compressor, at the increased speed necessary to deliver an increased amount of air under pressure to the engine. As indicated, the effect is especially noticeable when opening up the engine from idling speed, when the turbine is normally effectively inoperative.

An object of the invention is to provide a solution to the problem of turbine lag.

According to the invention, there is provided apparatus for use with a turbocharger for an internal combustion engine in a vehicle, comprising a supplementary air inlet device in the turbocharger compressor housing for delivering a stream of air for driving the compressor wheel, a separate air compressor unit powered from the vehicle power supply, a compressed air reservoir storing compressed air received from the said air compressor unit and valve means associated with operation of the engine throttle controlling supply of compressed air from the reservoir to the supplementae air inlet of the turbocharger compressor while the turbine of the turbocharger builds up speed responsively to opening of the engine throttle control.

The invention is further described with reference to the accompanying drawings, in which: Figure 1 shows the overall system diagrammatically; and Figure 2 shows the compressor of a turbocharger when fitted with the supplementary air inlet.

Referring to the drawings, Figure 1 shows a typical turbocharger for the internal combustion engine of a vehicle, comprising an air compressor 10 linked by a coupling shaft to a turbine 12. In normal use, exhaust gases are drawn into the turbine generally tangentially as indicated at A, and exhaust on-axis, as indicated at B. Within the turbine 12, the exhaust gases drive the turbine wheel, which is coupled to the compressor wheel. The compressor 10 receives air on-axis, as indicated at C, and tangentially exits air under pressure, as indicated at D, to the internal combustion engine.

There exists a problem, however, known as turbine lag, because when the throttle of the engine is opened up, it takes time for the exhaust gases to build up to the pressure required to drive the turbine, and thus the compressor, at the speed appropriate for delivery of pressurised air to the engine at the rate appropriate to the throttle opening, so that there is a delayed engine response to throttle operation. This is commonly especially noticeable when starting from idling, when the turbocharger is effectively inoperative.

In accordance with the invention, therefore, a supplementary air inlet in the form of a nozzle 14 is located in the compressor housing, as shown in Figure 2.

Referring back to Figure 1, the nozzle 14 receives air from a compressed air reservoir 16 when a valve 18 is opened. This valve 18 may conveniently be opened responsively to the operation of a switch controller 20, which could be a microswitch but is preferably a proportional controller such as a potentiometer, associated with the throttle 22, e.g. an accelerator pedal. In this way the turbocharger compressor is substantially instantly or at least very quickly brought up to speed when the throttle is opened up.

The compressed air reservoir is maintained by a separate compressor unit 24, which is powered from the vehicle power supply 26 via a suitable switch 28 which closes only when the compressor unit 24 requires to be driven to maintain pressure in the reservoir 16, for example by means of a reservoir pressure sensor 30.

As the turbine 12 of the turbocharger builds up to full operating speed responsively to increase in the pressure of the exhaust gases, in turn responsively to increased fuel delivery to the engine brought about by opening the throttle, the drive to the turbocharger compressor 10 via the supplementary air inlet or nozzle 14 requires to be gradually reduced and then stopped to allow normal operation of the turbocharger. To this end, the valve 18 is conveniently a gate valve or other proportionate valve which is gradually closed down under the control of a feedback signal from the exhaust system, or more conveniently by the engine management system 32, which detects and normally controls the behaviour of the turbocharger.

In a new vehicle, it is apparent that the engine management system may also control delivery of supply of compressed air to the nozzle 14 when the throttle is opened up. The present invention, however, is also applicable as a modification to an existing turbocharger.

The invention also relates to a modified turbocharger as aforesaid and a vehicle when fitted with said turbocharger.

Claims

1. Apparatus for use with a turbocharger for an internal combustion engine in a vehicle, comprising a supplementary air inlet device in the turbocharger compressor housing for delivering a stream of air for driving the compressor wheel, a separate air compressor unit powered from the vehicle power supply, a compressed air reservoir storing compressed air received from the said air compressor unit and valve means associated with operation of the engine throttle for controlling supply of compressed air from the reservoir to the supplementary air inlet of the turbocharger compressor while the turbine of the turbocharger builds up speed responsively to opening of the engine throttle control.

2. Apparatus according to claim 1, wherein the said valve means is a proportional valve.

3. Apparatus according to claim 1 or claim 2, wherein opening of the valve means is governed by a controller operable by the engine throttle.

4. Apparatus according to claim 3, wherein the controller is a proportionate controller.

5. Apparatus according to any of claims 2 to 4, in which closing of the valve means is controlled in proportionate relationship to build up of exhaust gas pressure at the turbocharger turbine.

6. Apparatus according to any of claims 2 to 5, wherein closing of the valve is controlled by an engine management system.

7. Apparatus substantially as hereinbefore described with reference to the accompanying drawings.

8. A turbocharger equipped with the apparatus of any of claims 1 to 7.

9. A vehicle equipped with the turbocharger of claim 8.