GB2557910A

GB2557910A - Supercharger with vaned diffuser

Info

Publication number: GB2557910A
Application number: GB1621337.3A
Authority: GB
Inventors: Lee Don
Original assignee: Valeo Air Management UK Ltd
Current assignee: Valeo Air Management UK Ltd
Priority date: 2016-12-15
Filing date: 2016-12-15
Publication date: 2018-07-04
Anticipated expiration: 2036-12-15
Also published as: GB2557910B; GB201621337D0

Abstract

An electric supercharger comprising an electric motor and a radial flow compressor assembly 1 is disclosed. The radial flow compressor assembly comprises a compressor wheel 11 rotatable on a drive-shaft 6 driven by the motor. Air flows from an inlet 3 through the compressor, a volute 4 and then to an outlet 5. A diffuser 9, comprising a plurality of movable vanes 7, is positioned between the compressor and the volute. The vanes are movable between an open configuration, allowing air to flow through to the volute, and a closed position. Closing the vanes provides a barrier to stop air flow through the supercharger. This may hermetically seal the supercharger if it bypassed, improving efficiency and negating any reduction in the effect of a turbocharger in a twin charging arrangement. Apparatus for supplying a compressed air charge to an internal combustion engine and a method of using said apparatus are also disclosed.

Description

(54) Title of the Invention: Supercharger with vaned diffuser Abstract Title: Supercharger with vaned diffuser (57) An electric supercharger comprising an electric motor and a radial flow compressor assembly 1 is disclosed. The radial flow compressor assembly comprises a compressor wheel 11 rotatable on a drive-shaft 6 driven by the motor. Air flows from an inlet 3 through the compressor, a volute 4 and then to an outlet 5. A diffuser 9, comprising a plurality of movable vanes 7, is positioned between the compressor and the volute. The vanes are movable between an open configuration, allowing air to flow through to the volute, and a closed position.

Closing the vanes provides a barrier to stop air flow through the supercharger. This may hermetically seal the supercharger if it bypassed, improving efficiency and negating any reduction in the effect of a turbocharger in a twin charging arrangement.

Apparatus for supplying a compressed air charge to an internal combustion engine and a method of using said apparatus are also disclosed.

At least one drawing originally filed was informal and the print reproduced here is taken from a later filed formal copy.

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Fig.l

Fig. 2

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Supercharger with vaned diffuser

Field of the Invention

The present invention concerns electric superchargers. More particularly, but not exclusively, this invention concerns electric superchargers comprising a vaned diffuser.

Background of the Invention

As a result of the desire to reduce carbon dioxide emissions from internal combustion engines, there is a tendency towards smaller (i.e. reduced capacity) engines, known as downsizing. A means to maintain acceptable levels of power output to these downsized engines, is the introduction of the conventional exhaust gas driven turbocharger. Whilst the turbocharger may increase the maximum power output of the engine, it is known to cause unacceptable levels of turbo-lag, often making the engine impractical in automotive applications. Installing a supercharger downstream of the turbocharger (i.e. between the turbocharger and the engine) has been suggested as a way of reducing this problem of excessive turbo lag.

In some charging arrangements, including those that use both a turbocharger and supercharger, a bypass system is implemented to allow the intake air to bypass the supercharger. However, a bypass does not provide a completely hermetic sealing and could introduce air leakage through the supercharger when the supercharger is not operating. This can cause inefficiencies and/or (in the case of twin charging arrangements) it may reduce the effect of the turbocharger, thereby inhibiting the performance of the charging arrangement.

The present invention seeks to mitigate at least one of the above-mentioned problems.

Summary of the Invention

The present invention provides, according to a first aspect, an electric supercharger comprising an electric motor and a radial flow compressor assembly, the radial flow compressor assembly comprising: a compressor wheel rotatable on a drive-shaft arranged to be driven by the motor; an air inlet through which inlet air can flow into the compressor wheel; a volute with an air outlet, and a diffuser positioned between the compressor wheel and the volute, wherein the diffuser comprises a plurality of vanes for guiding air flow through the diffuser, and wherein the vanes are moveable between: (i) an open configuration in which air is guided between adjacent vanes through to the volute scroll and (ii) a closed configuration in which the vanes form a barrier such that air cannot flow between the air inlet and the air outlet.

Where the supercharger is used in a charging arrangement that has a bypass mode, such that the air supplied to the engine can be arranged to bypass the supercharger (such arrangements may include a twin charging arrangement having both a supercharger and a turbocharger, or an arrangement having a supercharger alone), air leakage through the supercharger in the bypass mode is undesirable. To mitigate the effects of air leakage through the supercharger, the vanes of the supercharger according to the first aspect of the invention are movable to a position in which they form a barrier such that air cannot flow between the air inlet and the air outlet.

The supercharger according to the first aspect of the invention is also an improvement over an arrangement comprising a supercharger and a separate shut-off valve (for preventing flow through the supercharger) because it represents a space saving within a car engine bay. Furthermore, such an arrangement is easier to install than two separate components, and facilitates both the shut-off and the supercharger control being integrated in a single piece of software.

Each of the plurality of vanes may be independently moveable. The movement of the moveable vanes may be linked such that the moveable vanes are not independently moveable .

Each of the plurality of vanes may be rotatably mounted within the diffuser and rotatable between the open configuration and the closed configuration.

Each vane may have an axis of rotation. The length of each of the plurality of vanes may be greater than the distance between the axes of rotation of neighbouring vanes .

The barrier may encircle the compressor wheel. The barrier may be substantially annular. The barrier may be arranged co-axially with the axis of rotation of the compressor wheel.

Each of the plurality of vanes may be situated adjacent a neighbouring vane; the closed configuration may correspond to a configuration in which each of the plurality of vanes is moved towards the neighbouring vane .

Each vane may have a fore section at a first end of the vane and an aft section at a second, opposite, end of the vane. In the closed configuration the fore section of each vane may be adjacent to the aft section of its neighbouring vane.

Each vane may touch its neighbouring vane when in the closed configuration. However, a barrier having substantially the same effect may be achieved by moving the vanes such that each vane is spaced apart by a substantially insignificant gap.

All vanes within the diffuser may be moveable. According to a second aspect of the invention there is also provided an apparatus for supplying an internal combustion engine with a compressed air charge, the apparatus comprising a supercharger according to the first aspect of the invention and an upstream compressing device located upstream of the supercharger, wherein the apparatus is operable in a supercharging mode in which the supercharger provides the compressed air charge, and a bypass mode in which the supercharger is bypassed such that the upstream compressing device provides the compressed air charge, where in the bypass mode the plurality of vanes is moved to the closed position such that the barrier formed by the plurality of vanes prevents air flow between the air inlet and the air outlet of the supercharger when the apparatus is in the bypass mode.

Where the apparatus is operating in the bypass mode, and the internal combustion engine is being supplied with a compressed air charge from the upstream compressing device, moving the vanes within the supercharger to the closed position creates a barrier within the supercharger that prevents air flow between the air inlet and the air outlet of the supercharger, thereby mitigating the effects of air leakage through the supercharger. Such an arrangement is especially beneficially because the air typically exits the upstream compressing device at a temperature and pressure which can damage the internal components of the supercharger.

The upstream compressing device may be a turbocharger .

According to a third aspect of the invention, there is also provided a method of using the apparatus according the second aspect of the invention to supply a compressed air charge to an internal combustion engine, the method comprising the steps of moving the plurality of vanes to the closed position, using the upstream charging device to compress a mass of air, supplying the mass of air as the compressed air charge.

The method may comprise the further steps of moving the vanes of the supercharger to the open configuration, using the upstream charging device to compress a second mass of air to a first volume, subsequently using the supercharger to compress the second mass of air to a second volume, the second volume being smaller than the first volume, supplying the second mass of air as a second compressed air charge.

It will of course be appreciated that features described in relation to one aspect of the present invention may be incorporated into other aspects of the present invention. For example, the method of the invention may incorporate any of the features described with reference to the apparatus of the invention and vice versa .

Description of the Drawings

Embodiments of the present invention will now be described by way of example only with reference to the accompanying schematic drawings of which:

Figure 1

Figure 2

Figure 3

Figure 4 is a cross-sectional view of a radial flow compressor assembly of an electric supercharger according to a first embodiment of the invention;

is an axisymmetric schematic showing an arrangement of moveable vanes within a segment of a diffuser of the electric supercharger;

is the axisymmetric schematic of Figure 2 showing the moveable vanes in the closed position; and is a schematic diagram showing an apparatus for supplying an internal combustion engine with a compressed air charge, the apparatus including the supercharger according to the first embodiment of the invention.

Detailed Description

Figure 1 shows a radial flow compressor assembly 1 of an electric supercharger, according to a first embodiment of the invention. The compressor assembly 1 comprises a compressor wheel 11, an air inlet 3 through which inlet air can flow into the compressor wheel 11, a volute 4 with an air outlet 5, and a diffuser 9 positioned between the compressor wheel 11 and the volute 4. Only the upper part (i.e. the compressor assembly 1) of the electric supercharger is shown in Figure 1, but it will be appreciated that the supercharger comprises an electric motor (in the form of a Switched Reluctance Motor (SRM) 12 (not shown in Figure 1, but shown in Figure 4)) which drives the drive shaft 6 on which the compressor wheel 11 is mounted. The lower part of the supercharger also comprises other components (not shown) such as a motor housing with cooling jacket, and control electronics 12 (see Figure 4).

The supercharger of the first embodiment of the invention is operable in an open mode and a closed mode. In the open mode air is free to flow through the supercharger, between the air inlet 3 and the air outlet

5. In the open mode, as is well known, the inlet air is compressed via the rotating compressor wheel 11 expelling inlet air into the volute 4 via the diffuser ring 9. As the air passes through the diffuser ring 9, it is guided by vanes 7, located on the front plate 10 and extending up across the height of the diffuser 9. The vanes 7 are orientated to promote efficient airflow into the volute 4 .

In contrast to known arrangements, the supercharger of the first embodiment is also operable in a closed mode: in that closed mode, moveable vanes 7 within the supercharger are moved to a closed configuration in which they form a barrier within the supercharger such that air may not flow through the supercharger, and more specifically such that air may not flow through the diffuser 9. The closed mode will now be described in more detail with reference to Figures 2 and 3.

As can be seen from the schematic of Figure 2, the compressor assembly 1 of the supercharger comprises a plurality of vanes 7 situated within the diffuser 9 which are circumferentially equally spaced around the compressor wheel 11 for guiding air flow through the

- 8 diffuser 9 (this is sometimes referred to as a vaned diffuser). Figure 2 (and 3) shows a segment of the diffuser, but it will be appreciated the layout is repeated around the full circumference of the diffuser). Vaned diffusers per se are known and well understood by the skilled person. However, in the first embodiment of the invention, each vane 7 is rotatably mounted at a pivot point 13 coinciding with its centre chord, midway between the leading edge of the vane 7 and the trailing edge of the vane 7, and rotatable about the point 13 in clockwise and anticlockwise directions as indicated by the arrow labelled 'X' in Figure 2.

When the supercharger is used in conjunction with another charging device, for example a turbocharger (see Figure 4 and accompanying description below), it may be advantageous to block airflow through the supercharger when not in use. This is achieved by rotating each vane 7 towards its neighbouring vane 7 in the direction of the arrows labelled Ύ' in Figure 3 to a closed configuration in which the fore section 71 of each vane 7 is in physical contact with the aft section 72 of one of its neighbouring vanes 7, and the aft section 72 of each vane 7 is in physical contact with the fore section 71 of its other neighbouring vane 7. The fore section 71 being situated on a first side of the point of rotation 13 and the aft section 72 being situated on a second, opposite, side of the point of rotation 13 of each vane 7. The vanes 7 extend across the height of the diffuser ring 9 (see Figure 1), so in this position, corresponding to the supercharger 1 closed mode, the vanes 7 form an annular barrier that coaxially encircles the compressor wheel 11, thereby blocking the diffuser 9 section and preventing air flow between the air inlet 3 and the air outlet 5 of the supercharger 1.

Figure 3 shows the vanes 7 in the closed configuration where all vanes have been rotated by an identical angle in the direction of the arrow labelled Ύ' such that the vanes contact one another. However, it will be appreciated that in other embodiments, it may not be necessary to rotate all vanes identically; each vane may be rotated by a different angle, or in the direction opposite to the arrow labelled Ύ', to achieve the same effect.

Figure 4 is a schematic diagram showing an apparatus for supplying a three cylinder internal combustion engine 20 with a compressed air charge. The apparatus incorporates the supercharger 21 of the first embodiment of the invention, in combination with an upstream turbocharger 23. The apparatus 25 (marked by a dotted line) comprises the turbocharger 23, an exhaust gas recirculation (EGR) valve 26, a charge air cooler (CAC)

27, the supercharger 21 and a supercharger bypass valve

28. The CAC is positioned upstream of the supercharger in the arrangement shown in Figure 4; however, it is noted that in other arrangements, the CAC may be positioned downstream of the supercharger.

In accordance with conventional turbochargers, the turbocharger 23 is driven by the exhaust gases from the engine 20 passing through the Turbine stage 23a thereby driving the turbocharger compressor 23b. Some of the exhaust gas output of the engine 20 is returned as an input to the engine via the EGR valve 26.

The output of the turbocharger 23 is then fed through the CAC 27 before being either supplied directly to the engine 20 via the open bypass valve 28, or via the supercharger 21 (such that the compressed charge is further compressed) by closing the bypass valve 28. In the former scenario, leakage flow through the supercharger 21 might still occur despite the bypass valve 28 being open. To prevent this, the apparatus is operable in a bypass mode in which the supercharger 21 is switched to the closed mode, such that the vanes 7 in the supercharger 21 move to the closed configuration and form the barrier as described above with reference to Figures 2 and 3. This prevents leakage flow, and importantly protects the supercharger from unnecessary exposure to the high temperature/pressure air (with some CCV vapour) that is typically output from the turbocharger 23.

Whilst the present invention has been described and illustrated with reference to particular embodiments, it will be appreciated by those of ordinary skill in the art that the invention lends itself to many different variations not specifically illustrated herein.

For example, in a second embodiment of the invention (not shown), the diffuser comprises alternating moveable and fixed vanes such that every other vane is moveable. Each moveable vane sits between a pair of fixed vanes and supercharger may be configured to the closed mode by rotating each moveable vane to a position in which it blocks airflow between the pair of fixed vanes.

In another embodiment (not shown) the closed mode is achieved by rotating the vanes 7 as shown in Figure 3 but leaving a small gap between the neighbouring vanes 7 such that the neighbouring vanes 7 do not physically contact one another. Such an arrangement still inhibits significant airflow through the supercharger 1 such that the vanes function to form a barrier, but may be advantageous where the vane 7 material may be sensitive to wear and tear through repeated contact.

Where in the foregoing description, integers or elements are mentioned which have known, obvious or foreseeable equivalents, then such equivalents are herein incorporated as if individually set forth. Reference should be made to the claims for determining the true scope of the present invention, which should be construed so as to encompass any such equivalents. It will also be appreciated by the reader that integers or features of the invention that are described as preferable, advantageous, convenient or the like are optional and do not limit the scope of the independent claims. Moreover, it is to be understood that such optional integers or features, whilst of possible benefit in some embodiments of the invention, may not be desirable, and may therefore be absent, in other embodiments.

Claims

1. An electric supercharger comprising an electric motor and a radial flow compressor assembly, the radial flow compressor assembly comprising:

a compressor wheel rotatable on a drive-shaft arranged to be driven by the motor;

an air inlet through which inlet air can flow into the compressor wheel; a volute with an air outlet; and a diffuser positioned between the compressor wheel and the volute, wherein the diffuser comprises a plurality of vanes for guiding air flow through the diffuser, and wherein the vanes are moveable between:

(i) an open configuration in which air is guided between adjacent vanes through to the volute and (ii) a closed configuration in which the vanes form a barrier such that air cannot flow between the air inlet and the air outlet.

2. A supercharger according to claim 1 wherein each of the plurality of vanes is rotatably mounted within the diffuser and rotatable between the open configuration and the closed configuration.

3. A supercharger according to any preceding claim wherein the barrier encircles the compressor wheel.

4. A supercharger according to any preceding claim wherein each of the plurality of vanes is situated adjacent a neighbouring vane and the closed configuration corresponds to a configuration in which each of the plurality of vanes is moved towards the neighbouring vane.

5. A supercharger according to any preceding claim wherein each vane has a fore section at a first end of the vane and an aft section at a second, opposite, end of the vane and in the closed configuration the fore section of each vane is adjacent to the aft section of its neighbouring vane .

6. A supercharger according to any preceding claim wherein all vanes within the diffuser are moveable.

7. An apparatus for supplying an internal combustion engine with a compressed air charge, the apparatus comprising a supercharger according to any preceding claim and an upstream compressing device located upstream of the supercharger, wherein the apparatus is operable in a supercharging mode in which the supercharger provides the compressed air charge, and a bypass mode in which the supercharger is bypassed such that the upstream compressing device provides the compressed air charge, where in the bypass mode the plurality of vanes is moved to the closed position such that the barrier formed by the plurality of vanes prevents air flow between the air inlet and the air outlet of the supercharger when the apparatus is in the bypass mode .

8. An apparatus for supplying an internal combustion engine with a compressed air charge according to claim 7, wherein the upstream compressing device is a turbocharger.

9. A method of using the apparatus according to claim 7 or claim 8 to supply a compressed air charge to an internal combustion engine, the method comprising the steps of moving the plurality of vanes to the closed position, using the upstream charging device to compress a mass of air, supplying the mass of air as the compressed air charge .

10. The method of claim 9 comprising the further steps of moving the vanes of the supercharger to the open configuration, using the upstream charging device to compress a second mass of air to a first volume, subsequently using the supercharger to compress the second mass of air to a second volume, the second volume being smaller than the first volume, supplying the second mass of air as a second compressed air charge.

11. A supercharger substantially as herein described with reference to any of Figs. 1, 2, and 3 of the accompanying drawings.

12. An apparatus for supplying an internal combustion engine with a compressed air charge substantially as herein described with reference to any of Figs. 1, 2, 3, and 4 of the accompanying

5 drawings.

13. A method of supplying an internal combustion engine with a compressed air charge substantially as herein described with reference to any of Figs. 1,

10 2, 3, and 4 of the accompanying drawings.

Intellectual

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Office

Application No: GB 1621337.3 Examiner: Nicholas Wigley