GB2333803A - An ic engine intake duct having a bent baffle plate - Google Patents
An ic engine intake duct having a bent baffle plate Download PDFInfo
- Publication number
- GB2333803A GB2333803A GB9801753A GB9801753A GB2333803A GB 2333803 A GB2333803 A GB 2333803A GB 9801753 A GB9801753 A GB 9801753A GB 9801753 A GB9801753 A GB 9801753A GB 2333803 A GB2333803 A GB 2333803A
- Authority
- GB
- United Kingdom
- Prior art keywords
- baffle plate
- intake
- intake port
- flow
- high velocity
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Granted
Links
Classifications
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
- F02B—INTERNAL-COMBUSTION PISTON ENGINES; COMBUSTION ENGINES IN GENERAL
- F02B31/00—Modifying induction systems for imparting a rotation to the charge in the cylinder
- F02B31/04—Modifying induction systems for imparting a rotation to the charge in the cylinder by means within the induction channel, e.g. deflectors
- F02B31/06—Movable means, e.g. butterfly valves
- F02B31/08—Movable means, e.g. butterfly valves having multiple air inlets, i.e. having main and auxiliary intake passages
- F02B31/085—Movable means, e.g. butterfly valves having multiple air inlets, i.e. having main and auxiliary intake passages having two inlet valves
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
- F02B—INTERNAL-COMBUSTION PISTON ENGINES; COMBUSTION ENGINES IN GENERAL
- F02B31/00—Modifying induction systems for imparting a rotation to the charge in the cylinder
- F02B31/04—Modifying induction systems for imparting a rotation to the charge in the cylinder by means within the induction channel, e.g. deflectors
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
- F02M—SUPPLYING COMBUSTION ENGINES IN GENERAL WITH COMBUSTIBLE MIXTURES OR CONSTITUENTS THEREOF
- F02M26/00—Engine-pertinent apparatus for adding exhaust gases to combustion-air, main fuel or fuel-air mixture, e.g. by exhaust gas recirculation [EGR] systems
- F02M26/01—Internal exhaust gas recirculation, i.e. wherein the residual exhaust gases are trapped in the cylinder or pushed back from the intake or the exhaust manifold into the combustion chamber without the use of additional passages
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
- F02B—INTERNAL-COMBUSTION PISTON ENGINES; COMBUSTION ENGINES IN GENERAL
- F02B31/00—Modifying induction systems for imparting a rotation to the charge in the cylinder
- F02B2031/006—Modifying induction systems for imparting a rotation to the charge in the cylinder having multiple air intake valves
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
- F02B—INTERNAL-COMBUSTION PISTON ENGINES; COMBUSTION ENGINES IN GENERAL
- F02B2275/00—Other engines, components or details, not provided for in other groups of this subclass
- F02B2275/48—Tumble motion in gas movement in cylinder
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
- Y02T10/00—Road transport of goods or passengers
- Y02T10/10—Internal combustion engine [ICE] based vehicles
- Y02T10/12—Improving ICE efficiencies
Abstract
An intake system for an ic engine comprises an intake duct 20' and a rotatable bent baffle plate 24', which has a curved portion 22', mounted on a spindle 30' and movable between a first position, for low load operation, where the plate obstructs the majority of the duct 20' except for a small area 26' formed between the duct wall and the curved portion of the baffle 22' and a second position, for high load operation, where the baffle 24' does not restrict the duct 20' (figure 2b). Preferably the wall of the duct 20' may have a recess 21' so that the wall does not restrict rotation of the curved baffle portion 22'. The plate 24' may have perforations to allow a supplementary air flow to be created across the width of duct 20'. Additionally the baffle may be placed as close as possible to the valve port at the end of the duct to minimise the volume of gases that may be stored between the baffle and the port and into which fuel, and/or exhaust gases for an EGR system, may be introduced.
Description
INTAKE SYSTEM FOR AN INTERNAL COMBUSTION ENGINE
Background of the invention
The present invention relates to an intake system for an internal combustion engine for enabling the engine to operate with a stratified charge during part-load conditions and with a homogeneous charge under high load conditions.
Description of the prior art
Figure 1 of the accompanying drawings shows a known intake system for an internal combustion engine. Each engine cylinder 10 has two intake valves 12, 14 and a siamesed intake port 20. The cylinder 10 also has a central spark plug 18 and two exhaust valves 16. To assist in charge preparation, a baffle plate 24 is mounted in the intake port 20, the baffle plate 20 being in the form of a butterfly valve that has a cut-out 26 on one side so as not to obstruct the intake port fully when it is closed. When the baffle plate 24 is in an open position, the engine breathes normally and the baffle plate has little effect on the air flow. This is the position adopted by the baffle plate 24 under high load conditions. During part load conditions, on the other hand, the baffle plate 24 is moved to the illustrated position in which it partially obstructs the intake port 20 allowing air to enter the intake port 20 only through the cut-out 26 in the baffle plate 24. The effect of obstructing the flow is not to reduce the mass of the intake air as this is still determined by the main throttle of the engine. Instead, the baffle plate 24 serves primarily to vary the flow pattern within the intake port 20 so as to promote swirl in the intake charge as it enters the combustion chamber and at the same time promote homogeneous mixing within the intake port 20 resulting in a more uniform mixture of fuel and air if fuel is also introduced into the intake port 20. The enhanced mixing is derived from the large recirculation flow pattern created within the intake port 20 as a result of the sudden flow expansion behind the baffle plate 24 as the flow passes through the orifice formed by the cut-out 26. The benefit of homogeneous mixing using a baffle plate designed as described above is supported by experimental data published in Society of
Automotive Engineers Technical Paper SAE 961952 by Tomita et al.
In common with the above proposal, the present invention introduces a baffle plate in the intake port to achieve partial obstruction of the intake port with the aim of varying the flow pattern within the intake port. The intake system of the invention, on the other hand, differs from the above proposal in that the flow pattern within the intake port is designed to achieve exactly the opposite effect of reducing mixing and increasing the inhomogeneity of the intake charge across the width of the intake port in order to promote charge stratification in the combustion chamber.
Summary of the invention
According to the present invention, there is provided an intake system for an internal combustion engine having at least one cylinder and at least one intake valve through which intake charge can be drawn into the cylinder, the intake system comprising an intake port supplying the intake charge to the intake valve and a movable baffle plate arranged to restrict the flow into the intake port, the baffle plate being movable between an open position for high load operation in which the gas flow into the intake port is substantially unobstructed, and a closed position for low and part load operation in which gas flow is only allowed into the intake port through a restricted opening in the baffle plate, characterised in that the edge of the opening in the baffle plate is curved towards the intake valve, the curvature being such that in the closed position of the baffle plate a convergent flow passage is defined between the curved surface of the baffle plate and a wall surface of the intake port, to guide the intake flow into a high velocity stream moving generally parallel to the wall surface of the intake port towards the intake valve, the high velocity stream entraining the adjacent air and preventing eddies forming behind the baffle plate.
Instead of filling the volume of the intake port by sudden expansion and producing large eddies behind the baffle plate, as occurs in the prior construction illustrated in Figure 1, in the present invention most of the intake flow is guided to flow as a stream following the side of the intake port towards the intake valve with little flow circulation occurring in the remaining volume of the intake port behind the curved baffle plate.
The convergent flow passage formed by the curved baffle plate also has significantly lower flow resistance compared with the prior construction illustrated in Figure 1, the former being a convergent nozzle while the latter being a sharp edge orifice. Thus more flow can pass through the same flow cross-section or the same flow can pass through a smaller flow cross-section.
The flow pattern not only produces a stronger swirl within the combustion chamber, but also a more structured and substantially layered flow field in the engine cylinder in which any inhomogeneity in the intake charge will be maintained for a longer period of time. This will promote charge stratification in the cylinder if fuel is introduced into a specific part of the intake charge while the charge is in the intake port or in the cylinder. For example, if vaporised fuel is introduced into the intake port in the low gas velocity region behind the curved baffle plate, it will enter the cylinder separately without mixing -significantly with the high velocity asir layer and dwel near the centre of the cylinder, while the high velocity air swirls around the periphery of the cylinder.
It has been proposed to create a stratified intake charge by introducing a partition wall along the intake port to divide the port into two flow passages and to block one of the flow passages by a movable baffle plate. The resulting flow pattern across the width of the partitioned intake port is found to be quite similar to that produced across the width of the intake port in the present invention, even though a partition wall is absent. Thus the invention has the advantage of achieving a similar stratified intake charge but with a simpler design of the intake system where a curved baffle plate interacting with the wall of the intake port partially serves in lieu of a partition wall.
During high load conditions, the baffle plate is rotated to an open position about such an axis that the plane of all parts of the baffle plate is oriented parallel to the direction of flow and therefore offers little obstruction to the intake flow. In this case, the flow pattern in the intake port will be substantially uniform across the entire width of the intake port. To facilitate free rotation of the baffle plate to its open position, a groove may be provided in the intake port wall to engage the curved end of the baffle plate in case of dimensional interference.
During intermediate load conditions, the baffle plate may be moved progressively towards the closed position. At a predetermined part load condition, the baffle plate is in the final closed position and the remaining load range may be operated with the baffle plate fixed in this position.
The steeply changing velocity gradient across the width of the intake port when the baffle plate is closed is not immediately effective at the beginning of each intake period of the engine cycle because of the mass of gases that is stored in intake port downstream of the baffle plate which must be set in motion before a flow pattern is established. To minimise the buffering effect of this stored mass of gases, it is advantageous to place the baffle plate in the intake port as near as possible to the intake valve. To this end, the volume of the intake port lying between the intake valve and the baffle plate should preferably be less than half of the swept volume of each engine cylinder. Minimising the distance of the baffle plate from the intake valve also enhances the steep velocity gradient of the gases entering the combustion chamber as there is a reduced distance in which the high velocity layer can break away from the intake port wall.
If the intake valve is opened during the later part of the exhaust stroke of a four stroke engine cycle with the curved baffle plate in the closed position, some of the exhaust gases will flow back through the intake valve and a large proportion of this will be trapped in the volume of the intake port between the intake valve and the curved baffle plate while only a small proportion will escape past the baffle plate into the intake manifold branch. These trapped exhaust gases will enter the combustion chamber first during the induction stroke of the piston and serve as internally recirculated exhaust gases (internal EGR). This construction offers the advantage that the internal EGR gases will not mix significantly with the intake charge in the intake manifold branch. As a result, the EGR gases will be drawn back into the combustion chamber while they are still hot and reactive. The extent of intake and exhaust valve overlap can be varied by means of a variable valve timing mechanism to vary the proportion of internal EGR, but limiting the volume of the intake port between the intake valve and the curved baffle plate to no more than 50% of the swept volume of each engine cylinder, as proposed above, would limit the proportion of internal EGR to approximately 50% regardless of the valve timing.
Brief description of the drawings
The invention will now be described further, by way of example, with reference to the accompanying drawings, in which:
Figure 1 is, as earlier described, a representation of a known intake system employing a baffle plate with a cutout to modify the flow pattern in the intake port,
Figure la is an end view of the intake port in Figure 1 showing the baffle plate in a closed position,
Figure Ib is an end view of the intake port in Figure 1 showing the baffle plate in an open position, and
Figures 2, 2a and 2b are views similar to those of
Figures 1, la and Ib, respectively, showing an intake system of the present invention.
Detailed description of the preferred embodiments
The intake system of Figure 2 is generally similar to that already described by reference to Figure 1 and in order to avoid repetition, like components have been allocated like reference numerals but with the addition of a prime.
The primary difference between the intake system of
Figure 2 and that of Figure 1 resides in the shape of the baffle plate 24' which is curved at one edge 22' away from the plane of the plate fixed to a spindle 30'buy screws 28' and towards the intake valve 12'. The plate may additionally be curved slightly in an orthogonal plane in the shape of a saddle for increased rigidity but this is not shown in the drawings.
In the closed position, one edge of the curved plate 22' can be designed to fit snugly against the adjacent wall of the intake port and move away from the wall when the plate is rotated about its spindle 30' towards the open position. On the other hand, allowance must be made to avoid interference between the other edge of the curved plate 22' on the opposite side of the spindle 30' and the adjacent wall of the intake port. If the curved part 22' of the baffle plate 24' is to extend over the entire height of the intake port 20' when in the closed position, then it is possible to provide a recess 21' in the intake port wall to accommodate the edge of the plate 22' when it is rotated about its spindle 30' towards the open position.
Alternatively, the edge of the curved part 22' of the baffle plate can be chamfered so as not to extend over the entire height of the intake port but allow the plate 24' to rotate freely about its spindle 30'.
The baffle plate 24' is placed as close as practicable to the intake valves 12, 14 in order to minimise the stored volume of gases that lies between itself and the intake valves 12, 14, this volume being preferably less than half of the swept volume of each engine cylinder.
While the drawings show a cylinder having two intake valves and a siamesed intake port, it will be appreciated that the invention is equally applicable to engines having a single intake valve per cylinder.
The invention may also be used to enhance tumble and sandwiched stratification by curving both the outside edges of the baffle plate interacting with outside walls of the respective intake ports.
In an alternative embodiment of the present invention (not shown), the baffle plate 24' may be provided with small perforations to allow a supplementary mean flow distributed uniformly across the width of the intake port 20'. This supplementary mean flow moving in the same general direction as the high velocity stream would further assist the entrainment effect of the high velocity stream past the curved baffle plate 22' and prevent eddies forming behind the baffle plate 24'.
The same benefit may be achieved in a further embodiment of the present invention (not shown) where an external stream of fuel vapour or exhaust gases is introduced uniformly behind the baffle plate 24' to provide a supplementary mean flow distributed uniformly across the width of the intake port 20'.
Claims (8)
1. An intake system for an internal combustion engine having at least one cylinder and at least one intake valve through which intake charge can be drawn into the cylinder, the intake system comprising an intake port supplying the intake charge to the intake valve and a movable baffle plate arranged to restrict the flow into the intake port, the baffle plate being movable between an open position for high load operation in which the gas flow into the intake port is substantially unobstructed, and a closed position for low and part load operation in which gas flow is only allowed into the intake port through a restricted opening in the baffle plate, characterised in that the edge of the opening in the baffle plate is curved towards the intake valve, the curvature being such that in the closed position of the baffle plate a convergent flow passage is defined between the curved surface of the baffle plate and a wall surface of the intake port, to guide the intake flow into a high velocity stream moving generally parallel to the wall surface of the intake port towards the intake valve, the high velocity stream entraining the adjacent air and preventing eddies forming behind the baffle plate.
2. An intake system as claimed in claim 1, wherein the curved part of the baffle plate extends over the full height of the intake port and a recess is provided in the intake port wall to accommodate one edge of the plate when the baffle plate is rotated towards the open position.
3. An intake system as claimed in claim 1, wherein the curved part of the baffle plate is chamfered to extend over less than the full height of the intake port so as not to interfere with the rotation of the baffle plate towards the open position.
4. An intake system as claimed in any preceding claim, wherein the baffle plate is located in the intake port as near as possible to the intake valve.
5. An intake system as claimed in claim 4, wherein the volume of the intake port lying between the intake valve and the baffle plate is less than half of the swept volume of each engine cylinder.
6. An intake system as claimed in any preceding claim, wherein the baffle plate is provided with small perforations to allow a supplementary mean flow distributed uniformly across the width of the intake port, the supplementary mean flow moving in the same general direction as the high velocity stream assisting the entrainment effect of the high velocity stream and assisting in preventing eddies forming behind the baffle plate.
7. An intake system as claimed in any preceding claim, wherein an external stream of fuel vapour or exhaust gases is introduced uniformly behind the baffle plate to provide a supplementary mean flow distributed uniformly across the width of the intake port, the supplementary mean flow moving in the same general direction as the high velocity stream assisting the entrainment effect of the high velocity stream and assisting in preventing eddies forming behind the baffle plate.
8. An intake system for an internal combustion engine constructed, arranged and adapted to operate substantially as hereinbefore described with reference to and as illustrated in Figures 2, 2a and 2b of the accompanying drawings.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB9801753A GB2333803B (en) | 1998-01-29 | 1998-01-29 | Intake system for an internal combustion engine |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB9801753A GB2333803B (en) | 1998-01-29 | 1998-01-29 | Intake system for an internal combustion engine |
Publications (3)
| Publication Number | Publication Date |
|---|---|
| GB9801753D0 GB9801753D0 (en) | 1998-03-25 |
| GB2333803A true GB2333803A (en) | 1999-08-04 |
| GB2333803B GB2333803B (en) | 2001-07-04 |
Family
ID=10825993
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB9801753A Expired - Fee Related GB2333803B (en) | 1998-01-29 | 1998-01-29 | Intake system for an internal combustion engine |
Country Status (1)
| Country | Link |
|---|---|
| GB (1) | GB2333803B (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE10032740A1 (en) * | 2000-07-05 | 2002-02-21 | Mann & Hummel Filter | Air intake device for an internal combustion engine |
Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB1572641A (en) * | 1976-03-05 | 1980-07-30 | Nissan Motor | Internal combustion engine with intake arrangement to produce swirl in combustion chamber |
| EP0076632A1 (en) * | 1981-09-29 | 1983-04-13 | Bretton Patents Limited | Internal combustion engine |
| US4850317A (en) * | 1986-04-02 | 1989-07-25 | Mitsubishi Jidosha Kogyo Kabushiki Kaisha | Intake port device |
| US5640941A (en) * | 1995-12-04 | 1997-06-24 | Ford Motor Company | Internal combustion engine with stratified charge and tumble motion |
-
1998
- 1998-01-29 GB GB9801753A patent/GB2333803B/en not_active Expired - Fee Related
Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB1572641A (en) * | 1976-03-05 | 1980-07-30 | Nissan Motor | Internal combustion engine with intake arrangement to produce swirl in combustion chamber |
| EP0076632A1 (en) * | 1981-09-29 | 1983-04-13 | Bretton Patents Limited | Internal combustion engine |
| US4850317A (en) * | 1986-04-02 | 1989-07-25 | Mitsubishi Jidosha Kogyo Kabushiki Kaisha | Intake port device |
| US5640941A (en) * | 1995-12-04 | 1997-06-24 | Ford Motor Company | Internal combustion engine with stratified charge and tumble motion |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE10032740A1 (en) * | 2000-07-05 | 2002-02-21 | Mann & Hummel Filter | Air intake device for an internal combustion engine |
Also Published As
| Publication number | Publication date |
|---|---|
| GB2333803B (en) | 2001-07-04 |
| GB9801753D0 (en) | 1998-03-25 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| 732E | Amendments to the register in respect of changes of name or changes affecting rights (sect. 32/1977) | ||
| PCNP | Patent ceased through non-payment of renewal fee |
Effective date: 20100129 |