GB2228536A - Two stroke engine exhaust port control - Google Patents

Two stroke engine exhaust port control Download PDF

Info

Publication number
GB2228536A
GB2228536A GB9000030A GB9000030A GB2228536A GB 2228536 A GB2228536 A GB 2228536A GB 9000030 A GB9000030 A GB 9000030A GB 9000030 A GB9000030 A GB 9000030A GB 2228536 A GB2228536 A GB 2228536A
Authority
GB
United Kingdom
Prior art keywords
exhaust
piston
control element
control
exhaust duct
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.)
Withdrawn
Application number
GB9000030A
Other versions
GB9000030D0 (en
Inventor
Andreas Singer
Gunter Karl
Karsten Stansch
Matthias Hehnke
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
ZSCHOPAU MOTORRAD VEB
Original Assignee
ZSCHOPAU MOTORRAD VEB
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by ZSCHOPAU MOTORRAD VEB filed Critical ZSCHOPAU MOTORRAD VEB
Publication of GB9000030D0 publication Critical patent/GB9000030D0/en
Publication of GB2228536A publication Critical patent/GB2228536A/en
Withdrawn legal-status Critical Current

Links

Classifications

    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02D—CONTROLLING COMBUSTION ENGINES
    • F02D13/00—Controlling the engine output power by varying inlet or exhaust valve operating characteristics, e.g. timing
    • F02D13/02—Controlling the engine output power by varying inlet or exhaust valve operating characteristics, e.g. timing during engine operation
    • F02D13/028—Controlling the engine output power by varying inlet or exhaust valve operating characteristics, e.g. timing during engine operation for two-stroke engines
    • F02D13/0284—Variable control of exhaust valves only
    • 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
    • F02B33/00—Engines characterised by provision of pumps for charging or scavenging
    • F02B33/02—Engines with reciprocating-piston pumps; Engines with crankcase pumps
    • F02B33/28—Component parts, details or accessories of crankcase pumps, not provided for in, or of interest apart from, subgroups F02B33/02 - F02B33/26
    • F02B33/30—Control of inlet or outlet ports
    • 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
    • F02B75/00—Other engines
    • F02B75/02—Engines characterised by their cycles, e.g. six-stroke
    • F02B2075/022—Engines characterised by their cycles, e.g. six-stroke having less than six strokes per cycle
    • F02B2075/025—Engines characterised by their cycles, e.g. six-stroke having less than six strokes per cycle two
    • 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

Landscapes

  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Valve Device For Special Equipments (AREA)
  • Valve-Gear Or Valve Arrangements (AREA)
  • Output Control And Ontrol Of Special Type Engine (AREA)
  • Cylinder Crankcases Of Internal Combustion Engines (AREA)
  • Characterised By The Charging Evacuation (AREA)

Abstract

A piston 3 forming a wall of the exhaust duct 5 controls timing at the exhaust port 2. The piston 3 may be acted on by exhaust pressure or moved in dependence on engine load and speed. <IMAGE>

Description

A TWO STROKE ENGINE PROVIDED WITH MEANS FOR CONTROLLING THE EXHAUST CONTROL ANGLE The present invention relates to a two stroke engine provided with means for controlling the exhaust control angle in the exhaust duct in order to ensure favourable torque behaviour over a wide speed range.
The use of auxiliary exhaust ducts is known but they suffer from the disadvantage that, owing to the branching of the exhaust duct, the flow of exhaust gases during periods of high activity is adversely affected by eddy formation. In one known apparatus for controlling the exhaust control angle, a controller drum extending tangentially to the cylinder is guided directly downstream of the exhaust port through the exhaust duct, the drum being rotatable and adapted to the shape of the exhaust duct when the exhaust port is fully open. In the low-load range, rotation of the drum reduces the exhaust control angle and projects into the exhaust duct. The duct shape in this position of the'drum generates an eddy as a result of unfavourable flow conditions during the emission process and therefore does not create the optimum preconditions for turned intake pressure charging.
Various forms of flaps are also known which have been used to vary the exhaust control angle, the pivot point of said flaps being disposed parallel or perpendicular to the longitudinal axis of the cylinder. The disadvantage of these solutions however is that the control elements do not extend as far as the cylinder lining with the result that unfavourable flow conditions similarly occur. With these solutions, coking can also arise between the flap and the exhaust duct, thereby impairing the ability of the control element to function properly.
A slide valve control system is also known including a pipe-shaped distributing slide valve which is driven by the engine crank-shaft by way of a cam to open and close the intake and exhaust ports. In order to achieve a throttling of the intake and exhaust cross-sections to avoid a torque reduction in the medium speed range this pipe-shaped distributing slide valve can additionally be rotated about its axis, thereby varying the effective cross-sections of the intake and exhaust ports and doing so in a peripheral direction and not in terms of their height, so that such a construction is not suitable for controlling the exhaust control angle.
An exhaust control system is also known in which a flat slide valve, having a control edge adapted to the cylinder bore, is mounted perpendicular to the cylinder axis. When the distributing slide valve is in its operating position, it forms the control edge determining the emission process on the one hand and a portion of the wall on the cylinder head side of the exhaust duct on the other hand. If the exhaust duct is fully opened, long control paths have to be realised for the flat slide valve to terminate with its control edge flush with the wall of the exhaust duct and for transitions which are favourable to flow to arise.
These transitions favourable to flow are necessary in order, despite a fully opened exhaust port, to prevent any throttling action in the connecting duct.
It is an object of the invention to provide simple means which enable the exhaust control angle of a two-stroke internal combustion engine having at least one cylinder to be controlled according to the required operating conditions.
According to the invention, there is provided a two stroke internal combustion engine comprising a cylinder with an exhaust port communicating with an exhaust duct, a piston-like control element forming a portion of said exhaust duct and movable to vary the cross section thereof to control the exhaust control angle.
In a preferred embodiment, the control element is operable to narrow the cross section of the exhaust duct. The piston-like control element may be moved parallel to the cylinder axis or at an acute angle to it. In the case of control dependent on gas pressure, the piston-like control element and the regulating device may form a single structural component. The piston-like control element may be made of a ceramic material or a similar, heat-insulating material.
Preferably, the piston-like control element is longitudinally displaceable and disposed in the exhaust duct parallel to the cylinder longitudinal axis and, in dependence upon its position, determines the area of cross-section of the exhaust duct. The shape of the piston-like control element is adapted to that of the exhaust duct so that a continuously smooth duct progression is provided from the cylinder lining to the start of the exhaust gas system. The piston-like control element may be triggered according to the required operating conditions for each load and speed range.
By means of the construction according to the invention, the required exhaust angle is achieved in dependance upon the triggering of the piston-like control element and under optimum flow conditions in the exhaust duct.
A preferred embodiment of the invention will now be described, by way of example only, with reference to the accompanying drawings, in which: Figure 1 shows a two stroke internal combustion engine with a piston-like control element for the exhaust duct in a rest position, and Figure 2 is a view similar to Figure 1 but with the piston-like control element in its operating position.
Figures 1 and 2 show a two-stroke internal combustion engine in which exhaust duct aperture 2 in cylinder wall 6 of cylinder 1 is controlled by a working piston (not shown). For varying the exhaust port height and thus the exhaust control angle, a piston-like control element 3 is disposed parallel or at an acute angle to the longitudinal axis of the cylinder 1. The piston-like control element 3 is displaceable in exhaust duct 5 and is connected to a regulating device 4 by means of which a continuous lengthwise adjusting movement is achieved according to the required operating conditions.
The shape of the piston-like control element 3 is adapted to that of the exhaust duct 5, thereby achieving a continuously smooth duct transition with the result that, even when the port height is reduced, the flow path for the exhaust gases is not adversely influenced. The piston-like control element 3 is guided by the regulating device 4 which may be disposed either above or below the exhaust duct 5. Disposing it below the exhaust duct 5 creates more favourable cooling conditions, especially in air-cooled two-stroke engines.
To improve the cooling conditions, the piston-like control element 3 may also be made of a heat-insulating material, e.g. a ceramic material used in engine construction.
In order to permit appropriate displacement of the piston-like control element 3 to increase the exhaust port height and therefore the exhaust control angle, a control device may be provided which displaces the piston-like control element 3 in dependence upon the load and speed of the engine.

Claims (5)

1. A two stroke internal combustion engine comprising a cylinder with an exhaust port communicating with an exhaust duct, a piston-like control element forming a portion of said exhaust duct and movable to vary the cross section thereof to control the exhaust control angle.
2. An engine as claimed in claim 1 wherein the piston-like control element is displaceable parallel to or at an acute angle to the cylinder axis.
3. An engine as claimed in claim 1 or claim 2 including a regulating device connected to the control element, the arrangement being such that in the event of control in dependence upon exhaust gas pressure, the piston-like control element and the regulating device form a single structural component.
4. An engine as claimed in any preceding claim wherein the piston-like control element is made of a ceramic material or a similar heat-insulating material.
5. A two stroke internal combustion engine fitted with a control element substantially as herein described with reference to the accompanying drawings.
GB9000030A 1989-02-22 1990-01-02 Two stroke engine exhaust port control Withdrawn GB2228536A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
DD32593789 1989-02-22

Publications (2)

Publication Number Publication Date
GB9000030D0 GB9000030D0 (en) 1990-03-07
GB2228536A true GB2228536A (en) 1990-08-29

Family

ID=5607257

Family Applications (1)

Application Number Title Priority Date Filing Date
GB9000030A Withdrawn GB2228536A (en) 1989-02-22 1990-01-02 Two stroke engine exhaust port control

Country Status (3)

Country Link
JP (1) JPH02267315A (en)
DE (1) DE3937679A1 (en)
GB (1) GB2228536A (en)

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP3326837B2 (en) * 1992-12-28 2002-09-24 スズキ株式会社 Exhaust timing control device for two-stroke engine

Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB389125A (en) *
GB488403A (en) * 1936-11-28 1938-07-06 Fernand Radelet Improvements in or relating to exhaust valves of internal combustion engines
US4364346A (en) * 1979-12-27 1982-12-21 Yamaha Hatsudoki Kabushiki Kaisha Exhaust timing control device for a two-cycle engine
EP0174149A2 (en) * 1984-08-28 1986-03-12 Honda Giken Kogyo Kabushiki Kaisha Two-stroke engine with variable port timing
US4660514A (en) * 1980-04-21 1987-04-28 Outboard Marine Corporation Two-cycle internal combustion engine including means for varying cylinder port timing
US4672925A (en) * 1985-03-09 1987-06-16 Honda Giken Kogyo Kabushiki Kaisha Two-cycle engine

Family Cites Families (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE764731C (en) * 1937-03-23 1954-05-03 Andreas Soltau Two-stroke internal combustion engine
AT380537B (en) * 1980-12-18 1986-06-10 Bombardier Rotax Gmbh DEVICE FOR CONTROLLING THE EXHAUST TIME OF TWO-STROKE COMBUSTION ENGINES
DD226160A3 (en) * 1983-04-15 1985-08-14 Zschopau Motorrad Veb STARTING CONTROL FOR A TWO-STROKE INTERNAL COMBUSTION ENGINE
GB2145467A (en) * 1983-08-02 1985-03-27 Alexander Macfadzean Two-stroke I.C. engine exhaust ports
JPH061052B2 (en) * 1984-08-28 1994-01-05 本田技研工業株式会社 Exhaust timing control device for 2-cycle engine
GB2191537A (en) * 1986-05-29 1987-12-16 Josef Petr Prokopius Two-stroke engine with piston and valve controlled exhaust
DE3712750A1 (en) * 1987-04-15 1988-11-10 Bayerische Motoren Werke Ag Two-stroke internal combustion engine, especially of reciprocating piston type
DD260729A1 (en) * 1987-05-20 1988-10-05 Zschopau Motorrad Veb EXHAUST SYSTEM FOR A TWO-STROKE INTERNAL COMBUSTION ENGINE
DE3808342A1 (en) * 1988-03-12 1989-09-21 Klaue Hermann Two-stroke internal combustion engine with self-ignition and secondary expansion

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB389125A (en) *
GB488403A (en) * 1936-11-28 1938-07-06 Fernand Radelet Improvements in or relating to exhaust valves of internal combustion engines
US4364346A (en) * 1979-12-27 1982-12-21 Yamaha Hatsudoki Kabushiki Kaisha Exhaust timing control device for a two-cycle engine
US4660514A (en) * 1980-04-21 1987-04-28 Outboard Marine Corporation Two-cycle internal combustion engine including means for varying cylinder port timing
EP0174149A2 (en) * 1984-08-28 1986-03-12 Honda Giken Kogyo Kabushiki Kaisha Two-stroke engine with variable port timing
US4672925A (en) * 1985-03-09 1987-06-16 Honda Giken Kogyo Kabushiki Kaisha Two-cycle engine

Also Published As

Publication number Publication date
DE3937679A1 (en) 1990-08-23
JPH02267315A (en) 1990-11-01
GB9000030D0 (en) 1990-03-07

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WAP Application withdrawn, taken to be withdrawn or refused ** after publication under section 16(1)