GB2424673A - Articulated poppet valve assembly and operating system - Google Patents
Articulated poppet valve assembly and operating system Download PDFInfo
- Publication number
- GB2424673A GB2424673A GB0509687A GB0509687A GB2424673A GB 2424673 A GB2424673 A GB 2424673A GB 0509687 A GB0509687 A GB 0509687A GB 0509687 A GB0509687 A GB 0509687A GB 2424673 A GB2424673 A GB 2424673A
- Authority
- GB
- United Kingdom
- Prior art keywords
- valve
- head
- articulated
- poppet
- seat
- 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
- F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
- F01L—CYCLICALLY OPERATING VALVES FOR MACHINES OR ENGINES
- F01L3/00—Lift-valve, i.e. cut-off apparatus with closure members having at least a component of their opening and closing motion perpendicular to the closing faces; Parts or accessories thereof
- F01L3/06—Valve members or valve-seats with means for guiding or deflecting the medium controlled thereby, e.g. producing a rotary motion of the drawn-in cylinder charge
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
- F01L—CYCLICALLY OPERATING VALVES FOR MACHINES OR ENGINES
- F01L3/00—Lift-valve, i.e. cut-off apparatus with closure members having at least a component of their opening and closing motion perpendicular to the closing faces; Parts or accessories thereof
- F01L3/20—Shapes or constructions of valve members, not provided for in preceding subgroups of this group
-
- 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
- F02B3/00—Engines characterised by air compression and subsequent fuel addition
- F02B3/06—Engines characterised by air compression and subsequent fuel addition with compression ignition
-
- 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
A poppet-type valve assembly for controlling the flow of gases entering or leaving the combustion chamber of an i.c. engine via a respective intake or exhaust port, comprising a valve head 10 connected articulately to at least two separate valve stems 12,14 and characterised in that when the valve head 10 is lifted off its seat 22 by one or more of the valve stems 12,14 during the valve opening period of the engine cycle, the angular orientation of the valve head 10 relative to its seat 22 in the port is variable by differential movement of the separate valve stems 12,14 so as to vary the relative height of the lift opening of the valve at different points around the valve seat and thereby vary the main direction of gas flow entering or leaving the combustion chamber. The angular orientation of the valve head 10 may be adjusted to optimise charge tumble or swirl at different engine speeds and loads. The engine may have side-entry intake ports switchable to operate in 4-stroke or 2-stroke mode, with forward tumble, high swirl or high volumetric efficiency in 4-stroke mode and with reverse tumble in 2-stroke mode.
Description
ARTICULATED POPPET VALVE ASSEMBLY AND OPERATING SYSTEM
Field of the invention
The present invention relates to the design and operation of an intake or exhaust valve in the combustion chamber of an internal combustion engine.
Background of the invention
It is known in an internal combustion engine having intake and exhaust poppet valves operating according to a four-stroke engine cycle to introduce tumble motion within the combustion chamber for promoting mixture turbulence and/or charge stratification during the intake and compression phases of the four-stroke cycle. It is also known in an internal combustion engine having intake and exhaust poppet valves operating according to a two-stroke engine cycle to introduce tumble motion within the combustion chamber for promoting loop scavenging of the cylinder charge during the gas exchange phase of the two- stroke cycle. Tumble is herein defined as the rotation of the cylinder charge in a plane parallel with the longitudinal axis of the engine cylinder.
There are two directions of tumble motion, namely forward tumble and reverse tumble, according to the flow sequence past the walls of the combustion chamber. Forward tumble is herein defined wherein the flow from the intake port entering the combustion chamber is directed predominantly across the roof of the combustion chamber before being deflected by the cylinder wall towards the piston. Reverse tumble is herein defined wherein the flow from the intake port entering the combustion chamber is directed predominantly downwards along the cylinder wall before being deflected by the piston towards the roof of the combustion chamber.
In the case of a four-stroke engine with poppet valves, either direction of tumble motion is effective for promoting mixture turbulence and/or charge stratification, but other considerations, such as avoiding wetting of the fuel on the cylinder wall, favour the choice of forward tumble in order to reduce exhaust emissions.
In the case of a two-stroke engine with poppet valves, on the other hand, forward tumble is to be avoided because of the risk of short-circuiting of the intake air directly into the exhaust port without scavenging the contents in the cylinder when the intake and exhaust valves are simultaneously open during the gas exchange phase of the engine cycle. It is therefore important to introduce reverse tumble to ensure effective loop scavenging in two- stroke engine applications.
It is known to provide a vertical intake port of the top-entry design for producing reverse tumble. In the vertical port, the direction of the flow passage leading towards the poppet valve is substantially parallel with the longitudinal axis of the engine cylinder and is aimed close to the wall of the engine cylinder so that air entering the combustion chamber is directed predominantly downwards along the cylinder wall before being deflected by the piston towards the roof of the combustion chamber. This however makes the intake port stand up relatively high above the engine cylinder, increasing the height of the engine which is undesirable.
An alternative design for producing reverse tumble is to use a side-entry port where the direction of the port flow passage is primarily directed across the roof of the combustion chamber but a shrouded valve is provided with the shroud positioned to block the air flow in the primary direction of the port and channel the flow in a direction towards the cylinder wall. This reduces the height of the engine but the volumetric efficiency of the port is reduced because of the presence of the shroud.
A shrouded valve with the shroud positioned to direct the air flow in a tangential direction into the engine cylinder is also very effective for producing swirl in the combustion chamber. Swirl is herein defined as the rotation of the cylinder charge in a plane parallel with the crosssection of the engine cylinder. However, the volumetric efficiency of the intake port is again reduced because of the presence of the shroud and there is no means to remove the shroud when it is not required which is a disadvantage.
Summary of the invention
According to the present invention, there is provided a poppet-type valve assembly for controlling the flow of gases entering the combustion chamber of an internal combustion engine via an intake port, comprising a valve head connected articulately to at least two separate valve stems and characterised in that when the valve head is lifted off its seat by one or more of the valve stems during the intake valve opening period of the engine cycle, the angular orientation of the valve head relative to its seat in the port is variable by differential movement of the separate valve stems so as to vary the relative height of the lift opening of the valve at different points around the valve seat and thereby vary the main direction of gas flow entering the combustion chamber.
A valve stem is herein defined as a rod or wire connected to the valve head for the purpose of controlling the movement of the valve head. The valve stem is usually subjected to tensile load transmitted from a valve spring for holding the valve head firmly against its seat in the port. It may occasionally be subjected to compressive load when the valve head is accelerated by an actuator.
An actuator is herein defined as a force-transmitting means applied to the valve stem for controlling the opening and closing of the valve head relative to its seat in the port. It may include singly or in combination, hydraulic, pneumatic, electro-magnetic, electro-mechanical, mechanical and return spring force-transmitting means.
Preferably, the separate valve stems each has cylindrical cross-sections and moves along separate valve guides adjacent to one another in the cylinder head.
Alternatively, the separate valve stems have cross-sections forming in assembly a cylindrical cross-section, for the assembly to move along a common valve guide in the engine cylinder head.
In a preferred embodiment of the invention, a first valve stem is operated by a cam actuator and return spring, and a second valve stem is substantially free to move towards a predetermined end-stop position where it is stopped associated with a predetermined angular orientation of the valve head during the opening of the valve.
In another preferred embodiment of the invention, a first valve stem is operated by a hydraulic actuator and return spring, and a second valve stem is substantially free to move towards a predetermined end-stop position where it is stopped associated with a predetermined angular orientation of the valve head during the opening of the valve.
In a further preferred embodiment of the invention, a first valve stem is operated by a electro-magnetic actuator and return spring, and a second valve stem is substantially free to move towards a predetermined end-stop position where it is stopped associated with a predetermined angular orientation of the valve head during the opening of the valve.
In the all above preferred embodiments, the end-stop has at least two selectable predetermined positions associated with two predetermined angular orientations of the valve head when the valve is open. A shock absorber may preferably be incorporated with the end-stop in order to soften the load exerted at the connection with the valve head.
Preferably, the first valve stem is connected to act substantially at the centre of mass of the valve head for moving the valve head bodily without tilting the head, whilst the second valve stem is connected to act with a turning moment on the valve head for tilting the head pivotally relative to the first valve stem. Such force alignment would prevent any uncontrolled flapping of the valve head during operation when the whole assembly reciprocates at high speed.
Any one of the above preferred embodiments would enable the angular orientation of the valve head relative to its seat in the port to be adjusted so as to optimise the main in-cylinder gas motion (tumble or swirl) at different engine speeds and loads. When high tumble or high swirl is required, the angular orientation of the valve head may be tilted in the appropriate direction whilst the volumetric efficiency of the intake port could remain substantially unchanged because of the wider opening than the nominal lift of the tilted valve in the exit direction. Alternatively, when high volumetric efficiency is required, the valve head may be adjusted to stay in a parallel orientation with the valve seat in the port in order to provide a uniform nominal lift opening around the valve seat.
The invention may be used in an internal combustion engine with sideentry intake ports switchable to operate in either 4-stroke cycle mode or 2-stroke cycle mode, wherein the angular orientation of the valve head relative to its seat in the port may be adjusted so as to optimise the flow pattern within the combustion chamber in each cycle mode.
Thus the engine may be set to operate with forward tumble, high swirl or high volumetric efficiency in the 4-stroke mode, and with reverse tumble in the 2-stroke mode.
The invention may also be used in an exhaust port of the engine for optimising the main direction of gas flow leaving the combustion chamber. This could further improve the scavenging efficiency when reverse tumble is used in the above 2-stroke engine where the exhaust valve may be tilted with its exit direction furthest away from the intake valve.
Brief description of the drawing
The invention will now be described further, by way of example, with reference to the accompanying drawings in which: Figure 1 shows a schematic sectional view of a design example of an articulated poppet valve assembly and operating system, Figure 2 shows a simplified view of Figure 1 less the valve spring, at the full lift position of the valve head in a tilted angular position, Figure 3 shows a similar simplified view of Figure 1 at the full lift position of the valve head in a parallel angular position, and Figure 4 shows a schematic sectional and plan view of an alternative design example of an articulated poppet valve assembly and operating system, allowing free rotation of the valve about its main axis independently of the tilting direction.
Detailed description of the preferred embodiment
Figure 1 shows a poppet-type valve head 10 connected to two separate valve stems 12, 14. The first valve stem 12 has substantially bigger cross-section than the second valve stem 14, and the two cross-sections form in assembly a cylindrical cross-section as shown in Figure la so that the assembly moves along a common valve guide (not shown) in the cylinder head of the engine. The valve head 10 is connected articulately to the first valve stem 12 by a pivot link 16, and also to the second valve stem 14 by a resilient link 18.
The complete assembly 10, 12, 14, 16, 18 resembles a conventional poppet valve in profile with the valve head seated on a valve seat 22 in an engine port 20 and guided for movement in the conventional manner along a valve guide enclosing the two valve stems 12, 14 as one assembly. The first valve stem 12 is engaged by collets with a valve return spring 28 for keeping the valve head 10 firmly shut against its seat 22 when the valve is closed, and is moved by an actuator 26 acting at the end of the stem when the valve is being opened. Thus the first valve stem 12 and the pivot link 16 are designed to take the full spring load and the full actuation load in a similar manner to that of a conventional poppet valve stem. The actuator 26 may be a cam, rocker, electro-magnetic actuator or hydraulic actuator.
The second valve stem 14, in contrast, is not directly connected with the valve spring 28 or the actuator 26. Its sole function is to tilt the valve head 10 by another control means 15, 24 when needed, while the valve is being opened by the first stem 12. Preferably the first valve stem 12 is connected to act substantially at the centre of mass of the valve head 10 for moving the valve head 10 bodily without tilting the head 10, whilst the second valve stem 14 is connected to act with a turning moment on the valve head 10 for tilting the head 10 pivotally relative to the first valve stem 12. Such force alignment would prevent any uncontrolled flapping of the valve head 10 during operation when the whole assembly 10, 12, 14, 16, 18 reciprocates at high speed.
The movement of the second valve stem 14 is controlled by a spring collar 15 around the cylindrical valve stem assembly 12, 14, engaging fixedly with the second valve stem 14 but is free to slide along the first valve stem 12. By means of the collar 15, the second valve stem 14, whilst following the opening movement of the valve head 10, may be stopped at any point along its movement by an end-stop 24 as shown in Figure 2, at which point it will start tilting the valve head 10 about the pivot 16 as the first valve stem 12 continues to open the valve, On the other hand, if the second valve stem 14 is not stopped along its movement with the end-stop 24 retracted as shown in Figure 3, the valve head 10 will not be tilted and will remain parallel with its seat 22 in the full lift position.
Thus the angular orientation of the valve head 10 is adjustable by introducing or retracting the end-stop 24 via a slot cut across the pedestal of the valve spring 28, allowing the end-stop 24 to move freely below the valve spring 28. By linking a plurality of end-stops 24 to move together for a bank of valves along the cylinder head of the engine, all the valves may be controlled to tilt by the same degree, or not to tilt as required, by means of a single control rack represented by the dashed arrows.
No special control is necessary to re-align the valve head 10 against its seat 22 when the valve is being closed, this being accomplished automatically by the return spring 28 pulling the valve head 10 to touch at the nearest contact point in the seat 22 and then pivoting the valve head 10 about that point until the whole head is seated on the seat.
The collar 15 may be arranged to engage with another guide (not shown) for preventing it and the valve assembly from rotating about the stem axis, so that the desired angular orientation of the valve head 10 remains in the same position. This however may have a durability problem because of the lack of valve rotation.
Figure 4 shows an alternative design example with the objective of allowing free rotation of the valve head 10 independently of the tilting direction. In this case, the first and second valve stems 12, 14 each has cylindrical cross-sections and are located along separate valve guides adjacent to one another as shown in Figure 4a. The valve head 10 is connected articulately to the first valve stem 12 by a ball-and-socket joint 17, and also to the second valve stem 14 by a series of hinged linkages 18a, 18b. The linkage 18b could be made of stiff wire with two prongs engaged slidingly on opposite sides of a circular groove with the valve head 10 as shown in the plan sectional view.
In operation, when the second valve stem 14 is stopped along its travel by the end-stop 24 while the first valve stem 12 continues to open the valve, the prongs 18b will tilt in a direction hinged with the linkage 18a, and cause the valve head 10 to pivot in the same direction about the ball-and-socket joint 17 while the head 10 and the stem 12 are both free to rotate relative to the prongs 18b and the valve seat 22.
Whilst the above illustrations are schematic, it is essential that the articulated poppet valve assembly is designed substantially to similar dimensions and weight as a conventional poppet valve for it to function efficiently at high speed and have comparable durability. The linkages with the second valve stem should be narrow and thin in order to avoid obstructing the air flow.
Claims (11)
1. A poppet-type valve assembly for controlling the flow of gases entering or leaving the combustion chamber of an internal combustion engine via a respective intake or exhaust port, comprising a valve head connected articulately to at least two separate valve stems and characterised in that when the valve head is lifted off its seat by one or more of the valve stems during the valve opening period of the engine cycle, the angular orientation of the valve head relative to its seat in the port is variable by differential movement of the separate valve stems so as to vary the relative height of the lift opening of the valve at different points around the valve seat and thereby vary the main direction of gas flow entering or leaving the combustion chamber,
2. An articulated poppet àive assembly as claimed in claim 1, wherein the first valve stem is connected to act substantially at the centre of mass of the valve head.
3. An articulated poppet valve assembly as claimed in claim 1, wherein the second valve stem is connected to act with a turning moment on the valve head for tilting the head pivotally relative to the first valve stem.
4. A valve operating system for an articulated poppet valve assembly as claimed in any preceding claim, wherein at least one of the separate valve stems is moved by a valve actuator.
5. A valve operating system as claimed in claim 4, wherein the valve actuator is operated by at least one force-transmitting means, or combination of more than one force-transmitting means, including hydraulic, pneumatic, electro-magnetic, electro-mechanjcal, mechanical and return spring force-transmitting means.
- ]1 -
6. An articulated poppet valve assembly and operating system as claimed in any one of claims 1 to 4, wherein a first valve stem is operated by a cam actuator and return spring, and a second valve stem is substantially free to move towards a predetermined end-stop position where it is stopped associated with a predetermined angular orientation of the valve head during the opening of the valve.
7. An articulated poppet valve assembly and operating system as claimed in any one of claims 1 and 4, wherein a first valve stem is operated by a hydraulic actuator and return spring, and a second valve stem is substantially free to move towards a predetermined end-stop position where it is stopped associated with a predetermined angular orientation of the valve head during the opening of the valve.
8. An articulated poppet valve assembly and operating system as claimed in any one of claims 1 and 4, wherein a first valve stem is operated by a electro-magnetic actuator and return spring, and a second valve stem is substantially free to move towards a predetermined end-stop position where it is stopped associated with a predetermined angular orientation of the valve head during the opening of the valve.
9. An articulated poppet valve assembly and operating system as claimed in any one of claims 6 to 8, wherein the end-stop has at least two selectable predetermined positions associated with two predetermined angular orientations of the valve head when the valve is open.
10. An articulated poppet valve assembly and operating system as claimed in any preceding claim, used in an internal combustion engine wherein the angular orientation of the valve head relative to its seat in the port is adjusted so as to optimise the gas motion within the - 12 - combustion chamber at different engine speed and load operating conditions.
11. An articulated poppet valve assembly and operating system as claimed in any preceding claim, used in an internal combustion engine switchable to operate in either 4-stroke cycle mode or 2-stroke cycle mode, wherein the angular orientation of the valve head relative to its seat in the port is adjusted so as to optimise the charge scavenging flow pattern within the combustion chamber in each cycle mode.
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GBGB0506730.1A GB0506730D0 (en) | 2005-04-02 | 2005-04-02 | Engine valve assembly and operating system |
Publications (3)
| Publication Number | Publication Date |
|---|---|
| GB0509687D0 GB0509687D0 (en) | 2005-06-15 |
| GB2424673A true GB2424673A (en) | 2006-10-04 |
| GB2424673B GB2424673B (en) | 2009-03-04 |
Family
ID=34586608
Family Applications (2)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GBGB0506730.1A Ceased GB0506730D0 (en) | 2005-04-02 | 2005-04-02 | Engine valve assembly and operating system |
| GB0509687A Expired - Fee Related GB2424673B (en) | 2005-04-02 | 2005-05-12 | Articulated poppet valve assembly and operating system |
Family Applications Before (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GBGB0506730.1A Ceased GB0506730D0 (en) | 2005-04-02 | 2005-04-02 | Engine valve assembly and operating system |
Country Status (1)
| Country | Link |
|---|---|
| GB (2) | GB0506730D0 (en) |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN115111021B (en) * | 2022-06-29 | 2024-02-06 | 中国北方发动机研究所(天津) | Intake valve mechanism of rotor engine |
Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US1542617A (en) * | 1921-10-08 | 1925-06-16 | Frederick M Guy | Valve mechanism |
| US4159704A (en) * | 1978-04-03 | 1979-07-03 | General Motors Corporation | Articulated, spring-controlled intake valve |
| US4164209A (en) * | 1977-06-08 | 1979-08-14 | Grants William V | Internal combustion engine cylinder valve assembly |
-
2005
- 2005-04-02 GB GBGB0506730.1A patent/GB0506730D0/en not_active Ceased
- 2005-05-12 GB GB0509687A patent/GB2424673B/en not_active Expired - Fee Related
Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US1542617A (en) * | 1921-10-08 | 1925-06-16 | Frederick M Guy | Valve mechanism |
| US4164209A (en) * | 1977-06-08 | 1979-08-14 | Grants William V | Internal combustion engine cylinder valve assembly |
| US4159704A (en) * | 1978-04-03 | 1979-07-03 | General Motors Corporation | Articulated, spring-controlled intake valve |
Also Published As
| Publication number | Publication date |
|---|---|
| GB0506730D0 (en) | 2005-05-11 |
| GB0509687D0 (en) | 2005-06-15 |
| GB2424673B (en) | 2009-03-04 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PCNP | Patent ceased through non-payment of renewal fee |
Effective date: 20090604 |