GB2502806A

GB2502806A - Intercooler arrangement for a vehicle engine having a turbocharger and a supercharger

Info

Publication number: GB2502806A
Application number: GB1210072.3A
Authority: GB
Inventors: Samuel Magee; Gary Reid; Michael Blyth; James Allen
Original assignee: Jaguar Land Rover Ltd
Current assignee: Jaguar Land Rover Ltd
Priority date: 2012-06-07
Filing date: 2012-06-07
Publication date: 2013-12-11
Anticipated expiration: 2032-06-07
Also published as: GB201210072D0; GB2502806B

Abstract

A vehicle piston engine has an engine-driven supercharger 29 downstream of the compressor 23 of a turbocharger 18. A dual intercooler 24a, 24b leading to a common chamber 25 has parallel cooling paths which may be used selectively to provide effective charge cooling throughout the operating range of the engine. Intercooler 24a has inlet and outlet valves 33, 34, respectively, while intercooler 24b has an outlet valve 35. Intercooler 24b is connected by duct 28 to the supercharger 29, the outlet duct 30 of which is connected to intercooler 24b. At lower engine speeds the supercharger 29 is operated and valves 33 and 35 are closed so that inlet air flows sequentially through the intercoolers 24a, 24b. At higher engine speeds, the supercharger 29 is disengaged and acts to block flow through ducts 28 and 30; inlet air thus flows through the intercoolers 24a, 24b in parallel under the control of valves 34 and 35.

Description

Intercooler Arrangement For A Vehicle Engine

FIELD OF THE INVENTION

This invention relates to intercooling of the inlet charge of an internal combustion piston engine, in particular, but not exclusively, an engine having an exhaust turbocharger and a supercharger. Aspects of the invention relate to an intercooler, to a system, to a method and to a vehicle.

BACKGROUND

In order to increase the power and torque available from an internal combustion engine it is known to force the inlet charge into the cylinders rather than relying upon natural aspiration.

Typically an exhaust turbocharger may be provided to increase the pressure of the inlet charge. Alternatively or additionally an engine driven supercharger may be provided for the same purpose. In one arrangement a supercharger is provided for lower engine speeds, and a turbocharger is provided for higher engine speeds; there may be an overlap of operation to give a smooth transition.

Both a supercharger and a turbocharger add heat to the inlet charge passing therethrough, which makes the charge less dense. Power output is however related to mass flow, and accordingly it is usual to pass the pressurized inlet charge through an intercooler positioned upstream of the engine inlet manifold, to increase the charge density. Thus inlet charge density may be maximized in the cylinders, according to well known design criteria.

Packaging within the vehicle engine compartment, which may be defined as making efficient use of the available space, is often problematic. Space is typically restricted, and pathways for the inlet charge, particularly if routed via a turbocharger, a supercharger and an intercooler, may be difficult to find.

The present invention provides a novel arrangement which gives effective charge cooling for a combined supercharger and turbocharger installation; the invention also provides multiple pathways for efficiently packaging a supercharger and turbocharger installation in a vehicle.

SUMMARY OF THE INVENTION

According to an aspect of the invention there is provided a dual intercooler for the inlet tract of an internal combustion engine having a supercharger and a turbocharger, the dual

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intercoolor comprising first and second intercoolers in parallel, the intercoolers having respective inlets and outlets for common supply and delivery ducts, wherein a first intercooler includes a closure valve at the inlet thereof and a closure valve at the outlet thereof; a second intercooler includes a closure valve at the outlet thereof; the second intercooler has a supply branch for a charge compressor upstream of the outlet closure valve thereof; and the first intercooler has upstream thereof a return branch for said charge compressor, the return branch being downstream of the inlet closure valve of the first intercooler.

In one embodiment the inlet of the second intercooler is unobstructed.

This arrangement allows selection of gas flow pathways to permit sequential use of the dual paths when the inlet charge flows through both the turbocharger and the supercharger. In use the supercharger is used at comparatively low engine speeds and thus the flow capacity of the sequential intercoolers is adequate and does not provide any substantial restriction to flow.

At this operating condition the turbocharger may not provide substantial boost, but nevertheless transfers heat to the inlet charge flowing therethrough. Heat is thus rejected to the primary intercooler before the charge enters the supercharger, permitting more efficient supercharger operation with an acceptable pressure drop at this mass flow rate.

The gas flow paths may be used in parallel at high flow rates when the turbocharger is effective. The dual intercooler may give more packaging options in a congested engine compartment, since each individual intercooler is smaller than a combined intercooler of the same capacity.

In one embodiment the first and second intercoolers have a different capacity. Different capacities may allow a greater range of cooling to be applied to the inlet charge, and may also allow best use of available space within the engine compartment. The first and second intercoolers may however be adjacent, and if appropriate may be contained within a common housing or formed as a common structure.

Any suitable closure valve type may be selected, but in one embodiment butterfly valves are provided to give progressive closure of the respective pathway. Typically the position of each such valve is electronically controlled according to data retained in an electronic control unit (ECU) of an engine to which the dual intercooler is applied.

The dual intercooler is typically incorporated in a system comprising a single stage turbocharger and supercharger. The supercharger is in one embodiment disengageable from a drive source, whereupon the rotating elements thereof substantially block throughf low. Engagement and disengagement of the supercharger is typically via a clutch controlled via the engine ECU.

In one embodiment, the turbocharger includes a wastegate for modulating operation thereof, and the wastegate may also be electronically controlled via the engine ECU.

Aspects of the invention relate to an internal combustion piston engine incorporating the dual intercooler of the invention, and to a vehicle incorporating such an engine.

According to another aspect, the invention provides a method of providing charge cooling to an internal combustion engine having a supercharger and a turbocharger, the supercharger being downstream of the turbocharger compressor, and the method comprising the steps of providing two charge coolers having respective inlets and outlets; cooling the inlet charge twice when the supercharger is operating; cooling the inlet charge once when the supercharger is not operating.

The inlet charge is thus cooled after passing through the turbocharger, and again after passing through the supercharger.

In one embodiment the inlet charge is directed through a charge cooler before and after passing through the supercharger, and preferably the charge coolers are used sequentially when the supercharger is operating. When the supercharger is not operating, the charge coolers may be used singly or in parallel.

Within the scope of this application it is expressly intended that the various aspects, embodiments, examples and alternatives set out in the preceding paragraphs, in the claims and/or in the following description and drawings, and in particular the individual features thereof, may be taken independently or in any combination. For example, features described with reference to one embodiment are applicable to all embodiments, unless such features are incompatible.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments of the invention will now be described, by way of example only, with reference to the accompanying drawing of a schematic supercharger and turbocharger installation.

DETAILED DESCRIPTION

With reference to the drawing, a reciprocating piston internal combustion engine 10 comprises a plurality of cylinders each having a piston 11 connected by a connecting rod 12 to a crankshaft 13. Camshafts 14, 15 actuate inlet and exhaust valves 16, 17. An in-line OHC piston engine is illustrated for reasons of simplicity, but other kinds of valve arrangements and cylinder configurations are possible within the compass of this invention.

The inlet side comprises in sequence an air inlet 20, an airbox/plenum chamber 21, an air filter 22, and compressor wheel 23 of an exhaust turbocharger 18.

Downstream of the compressor wheel the inlet duct divides to two intercoolers 24a, 24b, the outlets of which enter a common chamber 25 from which a duct 26 passes to the engine inlet manifold 27.

The outlet from intercooler 24b is also connected to the inlet passage 28 of an engine driven supercharger 29, the outlet duct 30 of which is connected to the inlet side of intercooler 24a.

Intercoolers are well known and provide a means of heat transfer from the inlet charge to a lower temperature heat sink.

The supercharger 29 is coupled to a driven pulley 31 of the engine crankshaft 13 by a disengageable clutch 32.

Valves 33, 34, 35 are provided respectively at the inlet of the intercooler 24a upstream of the connection of the supercharger outlet duct 30, and at the outlets of both intercoolers 24a, 24b. Simple butterfly valves are illustrated, but any valve providing for progressive closure of the respective passageway may be suitable.

On the outlet side, an exhaust manifold 36 is connected via the turbine 37 of the exhaust turbo charger to an exhaust pipe 36, which may include a catalyst 39, a silencer 40, and the usual oxygen sensors 41, 42. The usual turbocharger relief valve (or wastegate 43) allows the turbine 37 to be bypassed when required, and may for example act as a relief valve to limit maximum pressure in the exhaust manifold 36.

The turbine and compressor wheels 37, 23 of the turbocharger 18 are connected by the usual shaft 19. The downstream side of the compressor wheel 23 is provided with a relief valve 44 to limit maximum pressure on the engine inlet side.

In general terms, the operation of an internal combustion engine with supercharger and turbocharger is well understood. Typically the supercharger will be engaged at lower engine speeds, and the turbocharger will operate at higher engine speeds; there may be some overlap. The relief valves 43, 44 may be electronically controlled in order to regulate or modulate pressure on the inlet and exhaust sides of the engine, according to an engine operating map contained in a suitable electronic control unit (ECU). Outlet flows from both the compressor wheel 23 and the supercharger are directed through suitable charge coolers, such as intercoolers 24a, 24b, to increase the density of the inlet charge.

The invention provides an intercooler arrangement which is both effective for all conditions of charge compression and capable of compact installation. Operation, in one embodiment, is as follows: At lower engine speeds, the turbocharger 18 generally provides little contribution to increased inlet manifold pressure, due to the low mass flow of exhaust gas. Accordingly the supercharger 29 is engaged to boost manifold pressure. In this mode, valves 33 and 35 may be closed so that inlet air flow is directed via intercooler 24b, ducts 28 and 30 and intercooler 24a to the chamber 25.

At higher engine speeds the supercharger 29 is disengaged because the turbocharger is effective at higher mass flow of exhaust gas. In this mode the supercharger, being stationary, substantially blocks gas flow through the ducts 28 and 30. The valves 34, 35 may be used together to regulate flow to the plenum chamber 25 so that the appropriate charge is delivered for the required output torque from the engine.

Thus at lower gas flows valves 33 and 35 are closed, and valve 34 is open to permit the supercharger outflow to be cooled to the maximum capacity of intercooler 24a. Inflow to the supercharger is cooled by the intercooler 24b. Should the intercoolers 24a, 24b be of different capacity, they may be arranged sequentially in order to better match cooling capacity to differing cooling requirements imposed by the relative additions of heat at the turbocharger and supercharger.

When operation of the supercharger is ceased, flow is permitted in parallel through the both intercoolers. Thus valves 33, 34, 35 are fully open, to allow cooling to the maximum extent.

The chamber 25 acts as a plenum if required, to equalize pressure as a result, for example, of differences in duct length and section of the two inlet paths..

By dividing the intercooler, the arrangement may become somewhat easier to fit within a congested engine space, whilst avoiding long pipe runs. By minimizing the length of the pipe runs, and hence the volume between the outlet of the turbocharger and the inlet to the plenum chamber 25, transient engine performance is enhanced.

Furthermore, cooling is provided for inlet gas exiting the turbocharger and the supercharger even if the engine is not operating at a speed at which the turbocharger is effective -thus heat transfer to the inlet gas from the turbocharger is removed by intercooler 24b prior to admission via duct 28 to the supercharger. When the supercharger is not required, the inlet gas passes directly through one or both intercoolers 24a, 24b, thus maximizing heat transfer and minimizing any pressure drop on the inlet side.

It will be understood that transition between supercharger only and turbocharger only will be progressive according to the engine operating map. Likewise the intercooler valves 33, 34, will be activated to give progressive change over between intercoolers 24a, 24b and between single and parallel flow paths through the intercoolers 24a, 24b.

Where maximum boost pressure is required, the arrangement allows the supercharger and turbocharger to work in conjunction whilst providing for cooling of the outlet streams thereof.

For simplicity, the intercoolers 24a, 24b are shown to be substantially identical in size, but it will be understood that they may be sized differently, and furthermore that the connecting ducts may be of different length and cross-sectional area. Although shown side by side, the dual intercooler may be incorporated within a common housing or comprise a common structure, or they may be entirely separate and distinct.

Claims

Claims 1. A dual intercooler for the inlet tract of an internal combustion engine having a supercharger and a turbocharger, the dual intercooler comprising first and second intercoolers in parallel, the intercoolers having respective inlets and outlets from common supply and delivery ducts, wherein: a first intercooler includes a closure valve at the inlet thereof and a closure valve at the outlet thereof; a second intercooler includes a closure valve at the outlet thereof; the second intercooler has a supply branch for a charge compressor upstream of the outlet closure valve thereof; and the first intercooler has upstream thereof a return branch for said charge compressor, the return branch being downstream of the inlet closure valve of the first intercooler.
2. A dual intercooler according to claim 1, wherein the inlet of the second intercooler is unobstructed.
3. A dual intercooler according to claim 1 or claim 2, wherein the first and second intercoolers have a different capacity.
4. A dual intercooler according to any preceding claim, wherein each closure valve is a butterfly valve.
5. An intercooler system of a vehicle internal combustion engine comprising a dual intercooler of any of claims 1-4, a turbocharger having a compressor wheel upstream of the intercooler supply duct, and a supercharger connected to the supply and return branches.
6. A system according to claim 5, wherein the supercharger further includes a disengageable drive clutch.
7. A system according to claim 5 or claim 6, wherein the turbocharger further includes a wastegate adapted to bypass the turbine wheel thereof.
8. A system according to any of claims 5-7, and further including a relief valve adapted to bypass the compressor wheel of the turbocharger.
9. A system according to any of claims 5-8, and further including a plenum chamber downstream of common delivery duct of the dual intercooler.
10. The intercooler system of any of claims 5-9, and further including an internal combustion piston engine having an inlet manifold supplied from the delivery duct of the dual intercooler, and an exhaust manifold supplying the turbocharger turbine wheel, the engine having an electronic control unit adapted to selectively control the closure valves of said dual intercooler.
11. A method of providing charge cooling to an internal combustion engine having a supercharger and a turbocharger, the supercharger being downstream of the turbocharger compressor, and the method comprising the steps of: providing two inlet charge coolers having respective inlets and outlets; directing the inlet charge sequentially through said coolers when the supercharger is operating; and directing the inlet charge in parallel through said coolers when the supercharger is not operating.
12. A method according to claim 11, wherein when the supercharger is operating, the inlet charge is directed through one charge cooler upstream thereof and one charge cooler downstream thereof.
13. A method according to claim 11 or claim 12, and comprising directing the inlet charge by means of closure valves in the respective inlets and outlets of the charge coolers.
14. A method according to claim 13, including the steps of providing a closure valve in the inlet of one charge cooler upstream of an outlet duct of the supercharger, providing a closure valve in the outlet of said one charge cooler, and providing a closure valve in the outlet of the second charge cooler upstream of an inlet duct of the supercharger.
15. A method of any of claims 11-14, and including the step of connecting the outlets of said charge coolers to a plenum chamber.
16. An engine or a motor vehicle having an intercooler or an intercooler system as claimed in any of claims 1-10.Amendment to the ciaims have been filed as follows Claims 1. A dual intercooler for the inlet tract of an internal combustion engine having a supercharger and a turbocharger, the dual intercooler comprising first and second intercoolers in parallel, the intercoolers having respective inlets and outlets from common supply and delivery ducts, wherein: a first intercooler includes a closure valve at the inlet thereof; a second intercooler includes a closure valve at the outlet thereof; the second intercooler has a supply branch for a charge compressor upstream of the outlet closure valve thereof; and the first intercooler has upstream thereof a return branch for said charge compressor, the return branch being downstream of the inlet closure valve of the first intercooler.2. A dual intercooler according to claim 1, wherein the first intercooler includes a closure valve at the outlet thereof. C')3. A dual intercooler according to claim 1 or claim 2, wherein the inlet of the second intercooler is unobstructed.4. A dual intercooler according to any preceding claim, wherein the first and second intercoolers have a different capacity.5. A dual intercooler according to any preceding claim, wherein each closure valve is a butterfly valve.6. An intercooler system of a vehicle internal combustion engine comprising a dual intercooler of any of claims 1 to 5, a turbocharger having a compressor wheel upstream of the intercooler supply duct, and a supercharger connected to the supply and return branches.7. A system according to claim 6, wherein the supercharger further includes a disengageable drive clutch.8. A system according to claim 6 or claim 7, wherein the turbocharger further includes a wastegate adapted to bypass the turbine wheel thereof.9. A system according to any of claims 6 to 8, and further including a relief valve adapted to bypass the compressor wheel of the turbocharger.10. A system according to any of claims 6 to 9, and further including a plenum chamber downstream of common delivery duct of the dual intercooler.11. The intercooler system of any of claims 6 to 10, and further including an internal combustion piston engine having an inlet manifold supplied from the delivery duct of the dual intercooler, and an exhaust manifold supplying the turbocharger turbine wheel, the engine having an electronic control unit adapted to selectively control the closure valves of said dual intercooler.12. A method of providing charge cooling to an internal combustion engine having a supercharger and a turbocharger, the supercharger being downstream of the turbocharger compressor, and the method comprising the steps of: C) providing two inlet charge coolers having respective inlets and outlets; directing the inlet charge sequentially through said coolers when the supercharger is F,.-.-operating; and 0 directing the inlet charge in parallel through said coolers when the supercharger is not operating. r13. A method according to claim 12, wherein when the supercharger is operating, the inlet charge is directed through one charge cooler upstream thereof and one charge cooler downstream thereof.14. A method according to claim 12 or claim 13, and comprising directing the inlet charge by means of closure valves in the respective inlets and outlets of the charge coolers.15. A method according to claim 14, including the steps of providing a closure valve in the inlet of one charge cooler upstream of an outlet duct of the supercharger, providing a closure valve in the outlet of said one charge cooler, and providing a closure valve in the outlet of the second charge cooler upstream of an inlet duct of the supercharger.16. A method of any of claims 12 to 15, and including the step of connecting the outlets of said charge coolers to a plenum chamber.
17. An engine or a motor vehicle having an inlercooler or an intercooler system as claimed in any of claims 1 to 11. C')N-(1 r