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
  • F01L33/00—Rotary or oscillatory slide valve-gear or valve arrangements, specially adapted for machines or engines with variable fluid distribution
  • F01L33/02—Rotary or oscillatory slide valve-gear or valve arrangements, specially adapted for machines or engines with variable fluid distribution rotary
• • 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
  • F02B53/00—Internal-combustion aspects of rotary-piston or oscillating-piston engines
  • F02B53/04—Charge admission or combustion-gas discharge
• • 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
  • F01L7/00—Rotary or oscillatory slide valve-gear or valve arrangements
  • F01L7/02—Rotary or oscillatory slide valve-gear or valve arrangements with cylindrical, sleeve, or part-annularly shaped valves
• • 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
  • F01L7/00—Rotary or oscillatory slide valve-gear or valve arrangements
  • F01L7/02—Rotary or oscillatory slide valve-gear or valve arrangements with cylindrical, sleeve, or part-annularly shaped valves
  • F01L7/04—Rotary or oscillatory slide valve-gear or valve arrangements with cylindrical, sleeve, or part-annularly shaped valves surrounding working cylinder or piston
• • 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
  • F01L7/00—Rotary or oscillatory slide valve-gear or valve arrangements
  • F01L7/08—Rotary or oscillatory slide valve-gear or valve arrangements with conically or frusto-conically shaped valves
• • 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
  • F01L7/00—Rotary or oscillatory slide valve-gear or valve arrangements
  • F01L7/18—Component parts, details, or accessories 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
  • F02B53/00—Internal-combustion aspects of rotary-piston or oscillating-piston engines
  • F02B53/02—Methods of operating

Definitions

• the present invention relates to internal combustion engines in which the control of the intake and exhaust of combustion gases is achieved by means of a rotary valve.
• Rotary valves are known, for example in the applicant's co-pending application No. GB 2467947A.
• Rotary valve engines are known to have problems of sealing as there is a conflict between minimising the clearances between the relatively rotating bodies, which improves efficiency, but runs the increasing risk of overheating and seizing. Being adjacent to the combustion chamber and in fact forming part of the combustion chamber, the valve is subjected to large thermal stresses, high gas pressures and high surface speeds with little or no lubrication. There are thus inherent problems in providing an adequate seal between the port formed in the valve body and the associated valve housing.
• valve housing has the advantage that it is able to conduct the heat away directly by the provision of external cooling means such as fins or water cooling.
• a further drawback of a steel valve body is that steel is a poor conductor of heat. As a result the surface of the valve body tends to get very hot leading to problems with excessive carbonisation.
• valve body may be run against the aluminium housing, with steel bands embedded within the housing being used to control the expansion of the aluminium. In either case the coefficients of expansion of the body and the housing will still tend not be closely matched. This can lead to problems with seizure if the valve body grows by more than the valve housing, and leakage if it grows by less.
• a further disadvantage of the known engines utilising a steel valve body and an aluminium housing occurs in cold conditions. Since the aluminium housing has a greater coefficient of expansion than the steel valve body, it contracts more under cold conditions and it has been found that, particularly at sub-zero temperatures, the gap can disappear altogether with the result that the engine is effectively seized and will not start. To enable cold starting to be achieved, it is necessary to provide a larger gap than is desired for engine efficiency.
• the present invention seeks to overcome these disadvantages by using aluminium for the rotary valve body as well as the valve housing, the surface of the aluminium valve body itself acting as the sealing surface, there being no additional sealing devices incorporated within the valve body or valve housing .
• valve body and valve housing expand at the same rate. This leads to more consistent sealing across the temperature range from cold starting up to maximum temperature, both reducing leakage when hot, and preventing the engine seizing when cold.
• the improved thermal conductivity of the aluminium valve body leads to lower surface temperatures on the valve and reduced carbon deposition.
• the reason for this surprising advantage is a type of thermal expansion feedback loop in the transmission of heat from the valve body to the valve housing. If clearance between the valve body and the housing increases during running, the heat conduction from the valve to the housing reduces causing the valve body to heat up to reduce the clearance. Similarly, if the clearance reduces, the conduction increases and more heat is conducted to the housing thus reducing the valve body temperature. This self-balancing, correction factor enables the use of the wider tolerance range.
• a rotary valve internal combustion engine having a piston connected to a crankshaft and reciprocatable in a cylinder, a combustion chamber being defined in part by the piston, and a rotary valve rotatable with a close sliding fit in a valve housing fixed relative to the cylinder, the rotary valve having a valve body containing a volume defining, in part, the combustion chamber and further having in a wall part thereof a port giving, during rotation of the valve, fluid communication successively to and from the combustion chamber via inlet and exhaust ports in the valve housing, wherein the rotary valve and the valve housing are formed of aluminium, the sealing function being carried out between a surface of the main body of the rotary valve and a contiguous surface of the valve housing.
• the total sealing function is carried out between the surface of the body of the rotary valve and the surface of the valve housing only, there being no additional sealing devices incorporated within the rotary valve or valve housing.
• the aluminium is an aluminium alloy with a copper content of up to 5%, and may be a eutectic aluminium.
• the interface surface of one or both of the valve body and the valve housing is provided with a hardened surface, which may comprise hard anodised aluminium, a ceramic or silicon carbide coating, a DLC (Diamond like Carbon) coating or a plasma nitrided surface.
• the port in the valve is a recess formed in the lower peripheral edge of the wall of the valve body adjacent to the combustion chamber, the recess extending upwardly from this lower edge of the wall of the valve to form the port in the side of the valve.
• the port in the valve is a bore in the wall part of the valve body, the wall having a lip formed below the port adjacent to the combustion chamber.
• Figure 1 shows a cross-sectional view of a single cylinder air cooled engine
• Figure 2 is a schematic view of one embodiment of the rotary valve body.
• FIG. 1 there is shown a single cylinder air cooled engine.
• the cylinder 2 has a piston 1 connected to a crankshaft 3 in the conventional manner for reciprocation in the cylinder 2.
• the upper part of the cylinder 2 is closed by a combustion chamber 4.
• the flow of inlet air/fuel mix and exhaust gas into and out of the combustion chamber 4 is controlled by a rotary valve 5.
• the valve is rotatable in a valve housing in the combustion chamber housing about an axis 5a which is parallel to the axis of rotation 3a of the crankshaft 3.
• the rotary valve 5 has a driven pulley 17 mounted thereon which is connected to a drive pulley 18 on the engine crankshaft 3 by a belt drive arrangement, comprising an endless belt 19 having a toothed profile on its inner surface which drivingly engage with corresponding teeth on the pulleys 17 and 18.
• the pulleys, and hence the endless belt 19 also, lie in a common plane 20.
• the rotation of the crankshaft 3 and hence the piston movement is coordinated with the rotation of the rotary valve 5 so that the engine operates on the conventional four stroke cycle.
• the diameter of the driven pulley 17 is twice that of the drive pulley 18 so that the rotary valve 5 rotates at half engine speed.
• the rotary valve consists of a plain active valve having a first cylindrical part in the form of a shaft 6 mounted on a ball bearing arrangement comprising a single race ball bearing 7, located on a side of the valve 5 remote from the combustion chamber 4.
• the valve has a slightly larger cylindrical body part comprising the valve body 11 itself which forms a shoulder 12 against which the ball bearing 7 is located.
• the valve body 11 extends into the combustion chamber and has in its interior a volume 9 which forms part of the combustion chamber 4.
• the valve body 1 1 is rotatable in a bore in a valve housing 8 in which the valve body 11 is a close sliding fit.
• the clearance is within the range of 10-30 microns between the rotary valve 5 and the bore of the valve housing 8.
• the valve 5 and the valve housing 8 are formed of aluminium.
• the aluminium may be an aluminium alloy with a high copper content, up to 5%, which gives good heat dissipation properties and good bearing qualities.
• a preferred aluminium is that designated as aluminium 2618.
• one or both of the interface surfaces of the valve body 5 and the valve housing 8 may be provided with a hard coating such as anodised aluminium, a ceramic or silicon carbide coating such as Nikasil (a registered trademark), a DLC (Diamond like Carbon) coating or a plasma nitride treatment.
• the shaft 6 part of the rotary valve 5 is only slightly smaller in diameter than the valve body 1 1 to provide the shoulder.
• the shaft part is solid to provide a good path for conducting heat from the valve body 1 1 to the exterior.
• the shaft on its end remote from the combustion chamber, to which the driven pulley 17 is connected, may have additional cooling means such as a heat sink 13 which may include fins or a fan rotatable with the driven pulley 17.
• the valve body has a port 14 which, during rotation of the valve, enables fluid communication successively to and from the combustion chamber via inlet and exhaust ports in the valve housing.
• the port is in the form of a recess formed in the lower peripheral edge 16 of the wall 15 of the valve body adjacent to the combustion chamber the recess extending upwardly from this lower edge of the wall of the valve to form the port 14 in the side of the valve.
• the port is a bore in the wall part of the valve body, the wall having a lip formed below the port at the lower peripheral edge 16 of the wall 15 adjacent to the combustion chamber.

Landscapes

• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• General Engineering & Computer Science (AREA)
• Chemical & Material Sciences (AREA)
• Combustion & Propulsion (AREA)
• Valve Device For Special Equipments (AREA)
• Valve-Gear Or Valve Arrangements (AREA)
• Combustion Methods Of Internal-Combustion Engines (AREA)

Priority Applications (4)

Applications Claiming Priority (2)

Publications (1)

Family

ID=46981377

Family Applications (1)

Country Status (6)

Families Citing this family (1)

Citations (8)

Family Cites Families (30)

• 2012
  • 2012-08-10 GB GB1214328.5A patent/GB2504773A/en not_active Withdrawn
• 2013
  • 2013-08-06 EP EP13750090.6A patent/EP2882943B1/en active Active
  • 2013-08-06 JP JP2015525932A patent/JP6247295B2/ja active Active
  • 2013-08-06 CN CN201380046254.0A patent/CN104781512B/zh active Active
  • 2013-08-06 US US14/420,099 patent/US9951685B2/en active Active
  • 2013-08-06 WO PCT/GB2013/000336 patent/WO2014023929A1/en not_active Ceased

Patent Citations (8)

Also Published As

Similar Documents

Legal Events