GB2365069A - I.c. engine air intake apparatus including an enclosure housing a vehicle battery, an air filter and an electric supercharger - Google Patents

Abstract

The air intake apparatus comprises a unitary hollow enclosure 50, eg of moulded plastics material, housing a motor vehicle battery 16, an air filter 9 and a charge-air compressor 10 drivable selectively by an electric motor 14. The engine air supply path passes from an air inlet 52 to an air outlet 54 via the air filter 9. The inlet 52 and outlet 54 define respectively an upstream end and a downstream end of the air supply path. The apparatus includes an automatic air bypass 13, 74, 84 within the enclosure 50 that directs air in the air supply path to the air compressor 10 when the compressor is activated, and which allows air to bypass the air compressor 10 when it is not activated. The air bypass may include a passive flap valve 13 which responds to air pressure differences in the enclosure. The enclosure 50 may be divided by a partition 92 into a battery compartment 56 and a compressor compartment 58. Power electronics 72 for the supercharger motor 14 may be provided in the enclosure 50.

Description

2365069 An Air Intake Arrangement for an Internal Combustion Engine The

present invention relates to an air intake arrangement 5 for an internal combustion engine.

There are many factors that characterize the torque output of any given internal combustion engine, for example the swept volume within cylinders, cylinder configuration, the bore-to-stroke ratio, the compression ratio, valve train arrangement, and the inlet & exhaust arrangement.

Engine developers are constantly "tuning" engines, that is, adjusting these parameters and others in the search for improved fuel economy and performance. However, this does not necessarily result in increased power or torque as perceived by the driver. In real world driving conditions it is engine torque that is most important to the driver's perception of performance (or performance feel), and particularly engine torque delivered at lower engine speeds (RPM), for example, below 3500 rpm for a typical light duty passenger car application.

For this reason, an engine may need to be tuned to give higher torque at lower RPM, but this will typically result in a loss of torque at higher engine speed, for example an engine speed that is above about 3500 rpm. This is particularly a problem with small capacity gasoline engines, for engines below about 1.8 litres for a gasoline engines and below about 2 litres for a diesel engine which tend to dominate in the European marketplace.

The same engine could easily be Ire-tuned' to deliver the same torque but at much higher crank speeds. This results in significantly higher peak power but at the expense of torque at lower rpm. Whilst this will appeal to the,sporting, driver, acceleration performance is reduced at lower engine speeds.

Engine designers have employed a multitude of techniques and technologies in an attempt to overcome this traditional compromise. Examples of such systems are variable geometry intake systems, variable camshaft timing and variable valve lift & timing. All of these approaches are designed to maintain more than one 'state of tune' depending on operating conditions.

Another commonly used technique is to reject engine tuning as a method for increased performance and instead pump air into the engine by means of a turbocharger or supercharger. Such forced induction generally results in significant increases in torque and power.

Such air compressors inevitably make some noise, and require cooling, particularly if the compressors are driven partly or entirely by an electric motor. This must be done in such a way that the space occupied by the compressor does not impinge unduly on other components near the engine. This is an increasingly difficult problem with modern motor cars, which are increasingly crowded under the hood or bonnet.

It is also important that an air compressor is inexpensive, if this is to be used with otherwise conventional, low capacity motor vehicle engines.

It is an object of the present invention to provide an air intake apparatus for an internal combustion engine which addresses these issues.

3 According to the invention, there is provided an air intake apparatus for supplying air to an internal combustion engine, comprising a unitary hollow enclosure, a motor vehicle battery, an air filter and an air compressor which when activated compresses air supplied to the engine, the enclosure housing the battery, air filter and compressor, an engine air supply path through the enclosure that passes from an air inlet to the enclosure to an air outlet from the enclosure via the air filter, said enclosure inlet and enclosure outlet defining respectively an upstream end of the air supply path and a downstream end of the air supply path, wherein the apparatus includes an automatic air bypass within the enclosure that directs air in the air supply path to the air compressor when this is activated, and which allows air to in the air supply path to bypass the air compressor when this is not activated.

The use of a single enclosure for the battery, air compressor, air filter and bypass provides manufacturing economies, particularly if the enclosure is formed predominantly from plastics materials.

Preferably, the air bypass includes a passive valve that operates automatically depending on air pressure differences within the enclosure. Such a passive valve will be cheaper than an actuated or motorised valve.

The passive valve may, as in a preferred embodiment of the invention, be a flexible flap valve that is resiliently biased to a closed position, and which is pulled open under the action of air pressure in the air supply path when the compressor is activated.

Also in a preferred embodiment, the air bypass includes a - 4 diffuser chamber into which bypassed air is admitted when the air compressor is not fully activated, the diffuser chamber having an outlet which mixes bypassed air and air expelled by the air compressor. The diffuser chamber may have an outlet aperture, with the air compressor having an outlet that includes an outlet pipe that extends through the diffuser chamber. The outlet pipe can then be provided with an exit that is surrounded by the outlet aperture with a gap extending around the outlet pipe exit and the outlet aperture. Preferably, the gap is an annular gap.

Cost can also be saved if the outlet aperture is the s ame as the air outlet to the enclosure.

In a preferred embodiment of the invention, the enclosure is partly divided by a partition wall into a battery compartment and a compressor compartment. The battery compartment then houses the motor vehicle battery and the compressor compartment houses both the air filter and the air compressor, with the air supply path extending through the partition wall.

The invention will now be described by way of example, with reference to the accompanying drawings, in which:

Figure 1 is a schematic diagram of a motor vehicle having a 1.4 litre,. four'cylinder engine system with an air intake apparatus that includes an electrically powered intake compressor, according to the invention; Figure 2 is a graph plotting engine torque against engine speed for the 1.4 litre engine of Figure 1 when naturally aspirated, tuned either for maximum torque at moderate engine speed, or maximum engine power at higher engine speed; Figure 3 is a graph similar to that of Figure 2, showing also the effect on engine torque output with the engine of Figure 1 when using the intake compressor; Figure 4 is a graph plotting engine compressor torque boost against driver throttle engine demand for the engine of Figure 1; Figure 5 is a graph of compressor demand against driver throttle angle demand for the engine of Figure 1; is Figure 6 is a perspective view of the air intake apparatus used with the engine of Figure 1; Figure 7 is an exploded view of a housing and internal components that form the air intake apparatus of Figure 6; Figure 8 is a top plan view of the air intake apparatus of Figure 7, showing two separate removable access panels on upper surfaces of the housing; Figure 9 is a top plan view of the air intake apparatus similar to that of Figure 8, but with the two access panels removed, and no components within the housing; Figure 10 is a perspective view of the empty housing of Figure 9; Figure 11 is a perspective view of a portion of the housing, with an access panel removed to show the compressor within the housing, and an air outlet pipe from the compressor extending through an air diffuser chamber to an air outlet from the housing; Figure 12 is a different perspective view of the portion of the housing shown in Figure 11, looking into the air outlet to show the arrangement of the air outlet pipe with respect to the air outlet and the diffuser chamber; Figure 13 is a perspective view from underneath of a portion of a divider plate that covers the air compressor and air diffuser chamber of Figures 11 and 12, showing an air flap valve in the diffuser plate in a closed position; Figure 14 is a perspective view similar to that of Figure 13, with the air flap valve removed to show an air grille through the divider plate by which bypass air flows into the diffuser chamber to the housing air outlet.

Figure 1 shows schematically part of a motor vehicle 7 having a supercharged reciprocating piston internal combustion engine 1, with four in-line cylinders 2, an air inlet manifold 4 and an exhaust manifold 6 leading to and from each of the cylinders 2, and a fuel injection system 8 for supplying fuel to cylinders 2 in a manner well- known in the art. An electrically driven supercharger 10 is provided upstream of the inlet manifold 4.

Air flows to the inlet manifold 4 through the supercharger 10 when this is operational, and when the supercharger is operating at below full capacity, or is disabled, also through an air bypass conduit 12 in parallel with the supercharger 10. Air is supplied to the supercharger 10 and/or the bypass 12 along an inlet air path 3.

The air bypass conduit 12 has an air valve 13 that automatically opens to permit inlet air 5 to bypass the supercharger when the supercharger airflow is is insufficient to charge the engine cylinders 2 with air. The air supply to the engine 1 is then controlled by the setting of a throttle valve 17 downstream of the supercharger 10 and bypass 12, and the activation of the supercharger 10. When the supercharger 10 is not activated, the engine 1 is normally aspirated, and when the supercharger 10 is activated, the airflow to the engine is increased.

The supercharger is driven only by an electrical motor (M) 14 powered by a conventional 12-volt lead/acid vehicle battery 16. The battery 16 also lies within the air supply path 3, so that inlet air flows around the battery 16.

An air filter 9 is provided in the air supply path 3 downstream of the battery 16 and upstream of the supercharger 10 and air bypass 12.

As will be explained in more detail below, the battery 16, filter 9, supercharger 10 and air bypass 12 are all houses within a hollow enclosure 50.

The vehicle driver (not shown) can control the engine power via a movable accelerator pedal assembly 18, that provides an electrical signal 20 to an engine control unit (ECU) 22. The engine control unit receives a number of input signals indicative of engine and vehicle operating parameters, including an engine speed signal 24 from an engine speed sensor 26. The engine control unit 22 calculates an engine torque demand f rom, the various input signals, and provides a number of output signals to control various vehicle and engine operating parameters, including a fuel injection control signal 28, throttle valve control signal 30 and a supercharger motor control signal 32. The engine torque demand is therefore set at least in part by the position of the accelerator pedal.

As will be explained in more detail below, when the driver moves the accelerator pedal to demand engine torque in excess of that which can be delivered by the engine 1 when naturally aspirated, the engine control unit 22 activates the supercharger motor 14 under certain engine moderate or low engine speeds, but not at high engine speeds.

Figure 2 shows a graph of engine torque against engine speed for a conventional four-cylinder in-line engine, such as that described above, but without supercharging.

As can be seen f rom curve 30 of Figure 2, the engine can be tuned to provide either good power at high engine speeds (,,power tune"), but at the expense of low-end torque.

Alternatively, as shown by curve 32, the engine can be tuned to give good torque at low and moderate engine speeds Ptorque tune"), but at the expense of top-end power. Whilst "power tune" will appeal to the 'sporting' driver, it will result in lower levels of satisfaction for the majority of car owners. The requirement to deliver good real world 'performance feel' commonly results in an engine torque output as shown in the "torque tune,, curve, where power at high engine speeds has been compromised in order to promote torque output below 3500 rpm. Although engine gearing can be selected to minimize undesirable 9 characteristics, in practice conventional engines are tuned to achieve a compromise.

With reference to Figure 3, in the preferred embodiment of the invention, a relatively low capacity engine, for example below about 1. 8 litres capacity, is tuned to give good power at high rpm, at the expense of torque at low engine speed, as illustrated by curve 30. This has the secondary effect of allowing good fuel economy at steady highway cruising speeds. As can be seen from curve 34, an increase in maximum engine torque is then provided with a supercharger torque boost (or equivalently engine power boost) when the driver demands power in excess of that available from a naturally aspirated engine, as shown by the curve with supercharger boost 'ISCBIl. The boost is made available under control of the engine control unit 22 only in a region of low 38 and moderate engine speeds 33, and is progressively limited to transition smoothly into engine power at point 35 without compressor torque boost in a region of higher engine speeds 36. This is done by progressively limiting the maximum allowable supercharger boost proximate a transition point 40, which in this example is taken at the maximum un-boosted engine torque. It is, however, possible to deviate either above or below this point, although a deviation too far below this point (in this example below about 3500 rpm) reduces the potential benefits provided by the supercharger, and a deviation too far above this point (in this example above about 5750 rpm) will lead to excess torque in a region of engine operation where this is not needed under most driving conditions, or desired from the point of view of fuel economy.

Thus, the engine controller enables use of the compressor 35 driver only in such a way that the engine torque output with the compressor torque boost peaks in the region of moderate engine speed.

The boosted torque curve could, however, transition 5 smoothly into the un-boosted torque curve 30 in a region of lower engine speeds 38, as shown by dashed line 39.

Figure 4 shows a graph of engine torquesupercharger boost against driver throttle angle demand between 00 and 900.

The diagonal straight lines on the graph are labelled with -engine speed in RPM, between 1250 RPM and 5400 RPM. The vertical scale corresponds between the difference in engine torque in Figure 3 between the boosted torque curve 34 and the un-boosted torque curve 30. At the maximum is throttle angle 900, the engine torque supercharger boost is the maximum value shown in Figure 3. As throttle angle demands declines from 900, so does the engine torque supercharger boost '. until this declines to 0 boost corresponding to curve 30 of Figure 3.

As can be seen from Figure 4, as the engine speed increases towards the transition point 35 of Figure 3, the slope of the engine torque supercharger boost curve declines, until at the transition point 35, there is no engine torque supercharger boost. This shows graphically the progressive disabling of the supercharger boost.

Figure 5 shows the operation of the supercharger in another way, with compressor demand plotted against driver throttle angle demand between 00 and 900. Again, the various lines are labelled with the engine speed in RPM.

The compressor demand is equivalent to the electrical power supplied to the supercharger motor 14. The plots begin at a compressor demand at about 0.2, at which point the air supplied by the supercharger begins to have an appreciable ef f ect on engine torque. As can be seen f rom Figure 5, as engine speed increases, so does the minimum compressor demand needed to appreciably boost torque. This is due to the increased air flow to the inlet manifold 4 as engine speed increases.

Figures 6 to 14 all show detailed views of the air intake apparatus according to the invention. Figure 6 shows an external perspective view of the unitary housing 50 that holds the battery 16, filter 9, compressor 10 and air bypass 12. The air supply path 3 through the unitary housing 50 begins at an air inlet 52 in a lower portion of the housing 50, and terminates at an air outlet 54 at a higher level in the housing 50.

is The housing 50 includes the battery compartment 56 and the supercharger compartment 58. Each compartment 56, 58 has a corresponding access panel 60, 62 which is removably attached by screws 64 to a unitary housing base 66 that forms a lower part of the enclosure 50.

The battery compartment access panel 60 has a pair of apertures 61,63, by which a pair of battery terminals 65,67 can protrude through the housing 50 when the battery access panel is affixed to the housing base 66.

The unitary housing base 66 is mounted at a number of supports 68 extending downwards from the housing base 66 to a steel mounting plate 70, which is itself bolted to an inner surface of an engine compartment (not shown).

The hollow enclosure 50 is formed from a moulded plastics material, for example ABS, or glass-filled nylon.

Figure 7 shows the mounting plate, hollow enclosure 50 and a number of components inside the enclosure 50 in an exploded, perspective, view. The battery 16 is housed within the battery compartment s6/ together with supercharger drive electronics 72.

The supercharger compartment 58 contains a larger number of components, including the filter 9, supercharger 10 and supercharger motor 14. Also in the supercharger compartment 58 are the divider plate 74 that extends 10 horizontally across a portion of the supercharger compartment 58 beneath the supercharger access cover 62, and the flap air bypass valve 13. The air f ilter 9 has a rectangular outline, and sits within a similar rectangular recess 56 within the divider plate 74. The divider plate 15 74 has an air grill 78 to the underside of which is attached the air flap 13, and a curved plate 80 to limit the deflection of the air flap 13 away from the grill 78. The supercharger compartment 58 is divided into a main 20 portion AV2, which houses the compressor 10, motor 14 and air filter 9, and a minor portion 84, which is referred to herein as a diffuser chamber 84. The divider plate air grill 78, and air flap 13 lie over the diffuser chamber 74, with a flexible seal 86 making an air- tight seal 25 between the diffuser chamber 84 and divider plate 74. The air supply path 3 between the air inlet 52 and air outlet 54 extends around the battery 16 and supercharger power electronics 72 within the battery compartment 56, 30 through an aperture 90 in a partition wall 92 that separates the battery compartment 56 from the supercharger compartment 58. As can be seen from Figure 7, the air aperture 90 is at a higher level in the battery compartment 56 from the air inlet 52. The air supply path 35 through the battery compartment 56 therefore generally rises towards the air aperture 90.

The air aperture 90 has a number of veins, one of which 94 is visible in Figure 7. These veins 94 direct the air flow into a lower portion of the supercharger compartment 58, in the vicinity of the supercharger motor 14. The air supply path therefore helps cool the supercharger motor 14 when this is operational. The air supply path 3 after flowing around the supercharger motor 14 rises vertically upwards through the air filter 9 in the divider plate 74. Into an air volume between the divider plate 74 and supercharger access panel 62. In Figure 7, this enclosed air volume is indicated generally by reference numeral 96.

When the supercharger is not operational, the air suction provided from the inlet manifold 4 holds the flap valve 13 downwards onto the flap valve limiting plate 80, so that air can flow through the air grill 78 in the divider plate 74, and into the diffuser chamber 84. From the diffuser chamber 84, the air is then f ree to pass into the air outlet 54. Although not shown, the air path then follows a conventional flexible hose to the throttle valve 17.

When the supercharger is operational, some air f rom the 25 enclosed air volume 96 will be drawn into an inlet 98 in an upper central portion of the supercharger 10. The supercharger air is then compressed and expelled at up to 50% above atmospheric pressure through thesupercharger outlet 100. A small rubber ring 102 connects the supercharger air outlet 100 to an inlet 104 to the diffuser chamber 84.

Until the supercharger 10 is operating at a high capacity, there will be some air also entering through the air flap 78 into the diffuser chamber 84. The air expelled by the supercharger 10 through the diffuser chamber air inlet 104 passes into a diffuser pipe 106 that tapers gradually outwards to a diffuser pipe outlet 108. The diffuser pipe outlet 108 has three radial fins 110 equilaterally spaced around the circumference around the space of the diffuser pipe outlet 108. The fins 110 slot into corresponding grooves 112 on inner surfaces of the air outlet 54 so that an annular gap 114 is maintained between the air diffuser pipe 106 and air outlet 54.

The air expelled by the supercharger 110 is therefore kept separate from air entering through the flap valve 13 into the diffuser chamber 84 until this air mixes downstream of the annular gap 114 surrounding the diffuser pipe outlet is 108.

It has been found that the air flow efficiency is increased by this arrangement, as energy in the air expelled by the supercharger 10 helps to pull air out of the diffuser chamber 84 supplied through the air flap valve 13.

In order to dampen noise and vibration, the supercharger 10 and its motor 14 are physically mounted through three rubber posts 116 spaced equidistantly around a cup-shaped aluminium mounting bracket 118 to which the supercharger 10 has been rigidly mounted. The three rubber mounts 116 sit on three corresponding posts 120 extending upwards from a lower portion of the supercharger compartment 58.

These three rubber mounts 116, together with the flexible short outlet hose 102 between the supercharger outlet 100 and diffuser chain inlet 104, dampen down any vibration which might be transmitted from the supercharger 10 and its motor 14 through to the body of the unitary housing 66.

- 15 The supercharger 10 is also vibrationally isolated from the divider plate 74 by a rubber ring 122 thatextends around the circumference of the supercharger air inlet 98.

The rubber ring 122 sits within a circular boss 124 that extends downwards from an undersurface 126 of the divider plate 74. The boss 124 has a passage 126 there through to allow air to flow through the divider plate 74 into the supercharger 10.

Referring now to Figures 9 and 10, these show how the air inlet path 3 extends into the battery compartment 56 initially in a recess 128 in a lower surface 156 of the battery compartment 56. The recess 128 gradually disappears downstream of the air inlet 52, thereby forcing inlet air to move laterally away from an access 130 of the air inlet 52 towards lateral side portions 132 ofthe flower 156, where there are a number of upstanding ribs 134 projecting from the side portions 132. The ribs 143 support an undersurface 136 of the battery 16, so that air channels 138 extend between the ribs 134 laterally away from the air inlet access 130. Inlet air is therefore directed across nearly the full undersurface of the battery, which helps to keep the battery cool. Once the inlet air reaches lateral side walls 140 of the battery compartment 56, the air is directed to flow upwards over corresponding vertically extending sides 142 of the battery 16 by vertically extending ribs 144 that project laterally inwards from the battery housing vertical side walls 140. The vertical ribs 144 also help to locate the battery 16 transversely within the battery compartment 56.

Some air will, however, flow downstream of the battery 16 at a lower level to encounter the supercharger power electronics 72, which is provided with metallic heat - 16 dissipation fins 146.

The temperature of the inlet air therefore increases as it passes through the battery compartment 56, but the air is still cool compared with the temperatures that may be reached by the supercharger motor 14. This therefore provides an efficient means of cooling the various components within the housing 50.

The air intake arrangement described above is both compact and economical to manufacture, and is suitable for use with relatively low capacity motor vehicle internal combustion engines.

- 17

Claims (12)

Claims:

1. An air intake apparatus for supplying air to an internal combustion engine, comprising a unitary hollow enclosure, a motor vehicle battery, an air f ilter and an air compressor which when activated compresses air supplied to the engine, the enclosure housing the battery, air filter and compressor, an engine air supply path through the enclosure that passes from an air inlet to the enclosure to an air outlet from the enclosure via the air filter, said enclosure inlet and enclosure outlet defining respectively an upstream end of the air supply path and a downstream end of the air supply path, wherein the apparatus includes an automatic air bypass within the enclosure that directs air in the air supply path to the air compressor when this is activated, and which allows air to in the air supply path to bypass the air compressor when this is not activated.

2. An air intake apparatus as claimed in Claim 1, in which the air bypass includes a passive valve that operates automatically depending on air pressure differences within the enclosure.

3. An air intake apparatus as claimed in Claim 2, in which the passive valve is a flexible flap valve that is resiliently biased to a closed position, and which is pulled open under the action of air pressure in the air supply path when the compressor is activated.

4. An air intake apparatus as claimed in any preceding claim, in which the air bypass includes a diffuser chamber into which bypassed air is admitted when the air compressor is not fully activated, the diffuser chamber having an outlet which mixes bypassed air and air expelled - 18 by the air compressor.

5. An air intake apparatus as claimed in Claim 4, in which the diffuser chamber has an outlet aperture, and the air compressor has an outlet that includes an outlet pipe that extends through the diffuser chamber, the outlet pipe having an exit that is surrounded by the outlet aperture with a gap extending around the outlet pipe exit and the outlet aperture.

6. An air intake apparatus as claimed in Claim 5, in which the gap is an annular gap.

7. An air intake arrangement as claimed in Claim 5 or Claim 6, in which the outlet pipe exit and outlet aperture both have a circular cross-section.

8. An air intake arrangement as claimed in any of Claims 5 to 7, in which the outlet aperture is the same as the air outlet to the enclosure.

9. An air intake apparatus as claimed in any preceding claim, in which the enclosure is partly divided by a partition wall into a battery compartment and a compressor compartment, the battery compartment housing the motor vehicle battery and the compressor compartment housing both the air filter and the air compressor, the air supply path extending through the partition wall.

10. An air intake apparatus as claimed in Claim 9, in which the battery compartment is in the air supply path upstream of the compressor compartment.

11. A motor vehicle, comprising an internal combustion engine for powering the vehicle and an air intake - 19 apparatus for aspirating the engine, wherein the air intake apparatus is as claimed in any preceding claim.

12. An air intake apparatus substantially as herein described, with reference to or as shown in the accompanying drawings.