Classifications

• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
  • F01B—MACHINES OR ENGINES, IN GENERAL OR OF POSITIVE-DISPLACEMENT TYPE, e.g. STEAM ENGINES
  • F01B17/00—Reciprocating-piston machines or engines characterised by use of uniflow principle
  • F01B17/02—Engines
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
  • F01B—MACHINES OR ENGINES, IN GENERAL OR OF POSITIVE-DISPLACEMENT TYPE, e.g. STEAM ENGINES
  • F01B29/00—Machines or engines with pertinent characteristics other than those provided for in preceding main groups
  • F01B29/08—Reciprocating-piston machines or engines not otherwise provided for
  • F01B29/10—Engines

Definitions

• the present invention relates to the field of engineering industry, in particular engine building, namely pneumatic piston engines (PPE).
• PPE pneumatic piston engines
• the invention can be used at transport in power drives and in power generation.
• High power consumption is the main problem of present-day transport. That is the reason why experts in the field of transport engineering face a task to provide speeds being adequate to up-to-date requirements with simultaneous increasing piston specific power of the engine and decreasing specific fuel consumption.
• ICE Internal combustion engines
• Increase of transport speed requires increasing engine power density.
• raise of engine power density in present-day ICEs is obstructed by high temperature in the working chamber of the engine and resulting thermo stress, as well as low reliability and low life of engine.
• ICE disadvantages one may point to its complex construction, in which a fuel-delivery system, a cooling system, and a system of turbocharger for the working chamber of the engine are needed.
• ICEs is the factor of the vessel survivability.
• the role of the ICEs is the same importance, because a failure of electric generator means an emergency stop of the train.
• Pneumatic piston engines are used as control and executing units in automation, as engine brakes in vehicles, as drives for mining machines and conveyors in mining industry. PPEs are ecologically clean, but their low efficiency obstructs their use in the sphere of transport and power generation.
• the nearest to the present invention is the method for operating and arrangement of a pneumatic piston engine according to certificate SU 663858, 1979, including supply of compressed air to the working chamber of the engine and subsequent exhaust of oddments of compressed air from the working chamber when the piston is in the region of bottom dead center (BDC).
• BDC bottom dead center
• supply of compressed air to the working chamber begins when the piston is in the region of top dead center (TDC) and ends when the piston is in the region of bottom dead center.
• TDC top dead center
• 3-4% of hydrogen-oxygen mixture is added to the air and the mixture obtained is passed through the catalytic oxidizing chamber.
• the air temperature rises to 170-220 °C and this results in increase of air volume by 1.6-1.8 times. This allows either to reduce proportionally air consumption and pipeline cross- section with the same piston specific power of the engine or to increase it without air consumption raise. Nevertheless, it does not provide achievement of high powers necessary for up-to-date transport and propulsion systems with simultaneous providing of efficiency.
• the purpose of the present invention is to create a method for operating of PPE providing high output power with high efficiency of operating, i.e. to increase piston specific power of the PPE and to decrease specific fuel consumption simultaneously.
• the next purpose of the present invention is to create a new PPE for providing realization of a new operating method. Creating a new power plant including a pneumatic piston engine providing the realization of the method stated above is also the purpose of the present invention.
• a method for operating of a pneumatic piston engine including supply of compressed air to the working chamber of a cylinder and subsequent exhaust of air out of the working chamber while the piston is in the region of bottom dead center, wherein
• the preferable mode of operating is a short-term (pulse) supply of compressed air while the means for supply of compressed air closes while the piston is in the position of 5° after TDC by angle of rotation of the crank of the crankshaft.
• the present invention provides the achievement of positive technical effect: a higher efficiency of transformation of compressed air energy to energy of engine shaft rotation, as compared with the known background art.
• the specific fuel consumption reduces, and a possibility to increase considerably the pressure of compressed air being supplied to the PPE appears as well, that results in significant raise of specific power of the PPE as compared with the PPE being known by the background art having the same engine parameters.
• the present invention solves a task of creating a new method for operating and an arrangement of the pneumatic piston engine providing increase of efficiency of operating of the engine.
• thermo stress is absent in pneumatic engines, contrary to the ICEs, and this allows to raise the pressure of compressed air being supplied to the working chamber of the PPE considerably within the limits of strength of material of the engine - up to that in the ICE and even higher.
• a more preferable one is the method of operating of the pneumatic piston engine according to the invention, which includes additionally at least one subsequent stage of operating of the pneumatic piston engine, thus forming a multi-stage method of operating, wherein:
• a pneumatic piston engine in which working fluid is compressed air (gas) and which contains a cylinder, wherein a piston is kinematically joined via a crank to a crankshaft, and a working chamber, which is provided with a means for supply of compressed air and a means for exhaust of air while the piston is in the region of BDC, - the means for supply of compressed air is arranged with capability to provide the start of supply while the piston is in the region within the range from 40° before TDC to 25° after TDC by angle of rotation of the crank of the crankshaft depending on the engine speed, and with the capability to provide the ending of supply of compressed air while the piston is in the region within the range from 0° to 90° after TDC by angle of rotation of the crank of the crankshaft.
• a more preferable one is the pneumatic piston engine according to the invention, which contains at least one consequently joined additional cylinder thus forming a multi-stage engine, herein
• the additional cylinder contains a piston kinematically joined via a crank to a crankshaft and a working chamber, which is provided with a means for exhaust of air while the piston is in the region of BDC;
• each preceding cylinder of the multi-stage PPE is provided with a means for pass-by of air to the working chamber of the subsequent additional cylinder, and the last one in a set of additional cylinders is provided with a means for exhaust of air; herein the said both means are arranged with capability for action while the piston of the corresponding cylinder is at a position not yet reaching the region of the BDC;
• the means for exhaust of air when the piston is in the region of BDC is arranged with possibility to reuse the exhausted air.
• said means for pass- by of air from the working chamber of the preceding cylinder to the working chamber of the subsequent additional cylinder can be arranged as a by-pass channel with a non-return valve in it, herein the inlet port of the by-pass channel is connected with a by-pass port of the working chamber of the preceding cylinder, the by-pass port being located above the region of bottom dead center of the piston, and the outlet port of the by-pass channel is connected with an inlet port of the working chamber of the subsequent additional cylinder.
• a power plant intended for realization of the method according to the present invention preferably contains a pneumatic piston engine according to the invention and a source of compressed air. This allows to provide high output power in a PPE-based system providing simultaneously low specific fuel consumption.
• a part of power generated in a pneumatic piston engine is directed to the drive of source of compressed air.
• a power plant intended for realization of the method according to the present invention contains a multi-stage pneumatic piston engine according to the invention, herein the bore of each subsequent cylinder and the diameter of its piston are larger than those in case of the preceding cylinder.
• Fig. 1 shows schematically construction of a one-stage one-sided supply PPE according to the present invention
• Fig. 2 shows an indicator diagram of operating of the PPE, in accordance with Fig. 1 , for the case the means for supply of compressed air closes while the piston is in position of 5° after top dead center by angle of rotation of the crank of the crankshaft;
• Fig. 3. shows an indicator diagram of operating of the PPE, in accordance with Fig. 1 , in the case the means for supply of compressed air closes while the piston is in position of 90° after top dead center by angle of rotation of the crank of the crankshaft;
• Fig. 4 shows an indicator diagram of operating of known PPE in the case the means for supply of compressed air closes while the piston is in the region of top dead center (for comparison);
• Fig. 5 shows schematically construction of a two-stage one-sided supply PPE according to the present invention, the power stroke in the first-stage cylinder;
• Fig. 6 shows schematically construction of a two-stage one-sided supply PPE according to the present invention, the back stroke in the first-stage cylinder;
• Fig. 7 shows an indicator diagram of operating of the ICE (for comparison)
• FIG. 2 Indicator diagrams in Fig. 2, Fig. 3, Fig. 4 show the operating of PPE for a particular case of engine speed 2.12 s "1 .
• the mechanism of operating of the PPE according to the invention is true for operating of a PPE for other engine speeds too.
• a one-stage one-sided supply pneumatic piston engine shown in Fig. 1 contains the following construction elements: 1 - PPE, 2 - cylinder, 3 - piston, 4 - crank, 5 - crankshaft, 6 - working chamber (over-cylinder space), 7 - means for supply of compressed air (inlet valve), 8 - means for exhaust of air (outlet valve), 9 - under-cylinder space.
• a PPE shown in Fig. 1 consists of a cylinder 2 containing a piston 3 kinematically joined via a crank 4 to crankshaft 5, and a working chamber 6 (over-cylinder space).
• the working chamber 6 contains a means 7 for supply of compressed air to the working chamber arranged as an inlet valve and a means 8 for exhaust of air, while the piston is in the region of bottom dead center, arranged as an outlet valve.
• the under-cylinder space 9 is bridged to atmosphere.
• the means 7 for supply of compressed air may be joined to an external source of compressed air.
• FIG. 2 The operating of a PPE is illustrated by the indicator diagrams given in Fig. 2 and Fig. 3.
• the diagrams show the change of pressure (p) of compressed air (gas) in the cylinder 2 of the engine 1 depending on the position of the piston 3 by angle of rotation ( ⁇ °) of the crank 4 of the crankshaft 5.
• the means 7 for supply of compressed air closes and supply of compressed air stops by the moment when pressure in the working chamber reaches the value of p max that corresponds to the piston position of 5° after top dead center by angle of rotation of the crank 4 of the crankshaft 5.
• the piston 3 goes on moving downwards doing work, the power stroke of the piston proceeds. While the piston 3 passes the region of bottom dead center, when pressure in the chamber drops to a value of few atmospheres (1.5-3 atm), the means 8 for exhaust of air to atmosphere opens (point c), pressure in the working chamber drops to a value equal to the atmospheric pressure p atm (point d) and the piston 3 goes upward freely.
• a free back stroke of the piston proceeds (segment d-a).
• the means 8 for exhaust of air closes again and the means 7 for supply of compressed air starts to open, and the working cycle of the engine repeats.
• the piston covers a distance corresponding to rotation of the crank of the crankshaft by an angle of approximately 7°.
• supply of compressed air to the working chamber of the engine proceeds during extremely short part of the piston stroke (segment a-b). "in a pulse mode" so to say.
• the means 7 for supply of compressed air m ax closes when the piston is in the position of 90° after top dead center by angle of rotation of the crank of the crankshaft (point ly). By that time the piston covers a distance equal to a half of the piston stroke (segment b-b').
• the exhaust of air also occurs in the region of bottom dead center (point c), the pressure in the chamber drops to the atmospheric pressure (point d), and a free back stroke of the piston occurs (segment d-a).
• the indicator diagram for PPE operating according to the method known from background art where supply of compressed air p max proceeds during all power stroke of the piston and ends in the region of bottom dead center (point c in Fig. 4), is given. During all period of supply of compressed air pressure in the working chamber keeps at the level of p max .
• the area of the indicator diagram illustrates the work produced by compressed air in the engine cylinder during one working cycle (the more the area the more the power supplied in the cylinder). It is seen from Fig. 2 that the area of the indicator diagram of operating of the engine according to the invention, in the case of preferable mode is smaller by a factor of 3.84 comparing with the case of the engine operating according to the method known from the background art (Fig. 4).
• the preferable mode of operating is the first mode described above, with a short- term supply of compressed air when closing of the means for supply of compressed air is carried out at the angle of rotation of the crankshaft of 5° after top dead center.
• the supply of compressed air to the working chamber of the PPE according to the invention when the angle of rotation of the crank of the crankshaft exceeding 90°, is inexpedient.
• a multi-stage PPE Operating of a multi-stage PPE according to the present invention is illustrated by an example of a two-stage one-sided supply PPE, which consists of the following construction components (Fig. 5 and Fig. 6): 10 - two-stage pneumatic piston engine, 11 - first-stage cylinder (preceding), 12 - second-stage cylinder (additional and/or subsequent), 13 - means for supply of compressed air to the working chamber of the first-stage cylinder (inlet valve), 14 - working chamber of the first-stage cylinder, 15 - means for exhaust of air out of the working chamber of the first-stage cylinder (outlet valve), 16 - piston of the first-stage cylinder; 17 - by-pass channel, 18 - nonreturn valve, 19 - by-pass outlet, 20 - inlet port of the working chamber of the second-stage cylinder, 21 - working chamber of the second-stage cylinder; 22 - piston of the second-stage cylinder, 23 - means for exhaust of air out of the
• Two-stage PPE consists of a first-stage cylinder 11 and a second-stage cylinder 12.
• the first-stage cylinder 11 as well as the cylinder 2 of a one-stage engine 1 according to Fig. 1 is supplied with a means 13 for supply of compressed air p max to a working chamber 14 of the engine arranged as an inlet valve and with a means 15 for exhaust of air out of the working chamber 14 to atmosphere, while its piston 16 passes the region of bottom dead center, arranged as an outlet valve. It is possible to join the inlet valve 13 to an external source of compressed air.
• the first-stage cylinder 11 is connected to the second-stage cylinder 12 via a by-pass channel 17 provided with a non-return valve 18 in it.
• the inlet port of the by-pass channel 17 is joined to a by-pass outlet 19 of the cylinder 11 , the by-pass outlet 19 being located in the working chamber 14 above the region of bottom dead center of the piston 16.
• the outlet port of the by-pass channel 17 is joined to an inlet port 20 of a working chamber 21 of the second-stage cylinder 12.
• the second-stage cylinder 12 is supplied with a means 23 for exhaust of air, arranged as an outlet port located in the working chamber above the region of bottom dead center of the piston 22.
• the outlet port 23 and under-cylinder spaces 24 and 25 of both cylinders are bridged to the atmosphere.
• the pistons 16 and 22 of cylinders of both stages are kinematically joined to cranks 26 and 27 of the common crankshaft 28.
• a means 29 for exhaust of air, while the piston is in the region of bottom dead center is placed, arranged as an outlet (exhaust) valve.
• a multi-stage engine operates as follows.
• Compressed air under pressure of p ma ⁇ is fed to the working chamber 14 of the cylinders 11 through the inlet valve 13 (Fig. 5), as well as in the case of one- stage engine 1 according to Fig. 1 , during a minor part of piston stroke.
• the by-pass channel 17 turns out to be opened into the working chamber 14 of the cylinder 11 for a short time.
• the compressed air under residual pressure of p res passes into the by-pass channel 17, and opens the non-return valve 18, and then the air passes to the working chamber 21 of the second-stage cylinder 12.
• piston 16 of cylinder 11 makes its back stroke (Fig. 6). While piston 16 passes the region of bottom dead center, the outlet valve 15 for exhaust of air out of cylinder 11 to the atmosphere opens; and the piston 16 makes a free stroke upwards.
• the piston 22 of the second-stage cylinder makes its working stroke. Herein the non-return valve 18 is closed.
• the piston 22 While moving upwards, the piston 22 passes by the outlet port 23, the working chamber of the cylinder 12 turns to be isolated from the atmosphere; and the piston 22, during its further movement upwards, compresses the air (which initial pressure is equal to atmospheric pressure p at m) in this chamber. This reduces the efficiency of the entire system of two-stage engine.
• the cylinder 12 is provided with means 29 (which is similar to the outlet valve 15) for exhausting the oddments of compressed air to the atmosphere when the piston 22 is in the region of bottom dead center. This provides free upwards motion of the piston 22.
• the means 29 closes before the following pass-by of air from the cylinder 11.
• Equation for calculating the power generated in the PPE Equation for calculating the power generated in the PPE:
• N,E is indicated power of PPE (kW);
• Pi is mean indicated pressure (Pa);
• N is engine speed (s _1 );
• S is piston stroke (m); is number of cylinders.
• Equation for calculating the power supplied in air compressor to obtain the amount of compressed air necessary for operating of PPE is as follows:
• ⁇ /,c is indicated power of air compressor (kW);
• Pi is mean indicated pressure of air compressor equal to mean indicated pressure in PPE (Pa); V s is the amount of air produced by air compressor per second
• H is length of piston stroke at the moment when supply of compressed air to the working chamber ends (m).
• the amount of air consumed in PPE per one revolution of the crankshaft in all cylinders of the engine equals to
• V, [v . /]. ⁇ (m 3 /s)
• n is engine speed 2.12 s 1 .
• the length of the piston stroke H at the moment of ending of supply makes 0.166 m.
• a loss factor which equals 2, accounting for the dead space, was introduced in this case, thus doubling the volume of the working chamber and air consumption:
• the pneumatic piston engine according to the invention may be arranged using known technologies and applying known up-to-date materials and equipment.
• the pneumatic piston engine according to the invention may be used as a motor-car engine and a main marine engine, as well as a railway transport engine.
• ICEs which have reached their power limit and do not meet the ecology criteria are used in these fields.
• the present invention allows to construct powerful, economic and ecologically more clean transport engines of various classes. On the basis of the present invention, power plants may be realized too.

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• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• General Engineering & Computer Science (AREA)
• Compressors, Vaccum Pumps And Other Relevant Systems (AREA)
• High-Pressure Fuel Injection Pump Control (AREA)
• Shafts, Cranks, Connecting Bars, And Related Bearings (AREA)
• Valve Device For Special Equipments (AREA)
• Fluid-Driven Valves (AREA)
• Actuator (AREA)
• Reciprocating Pumps (AREA)
• Control Of Vehicle Engines Or Engines For Specific Uses (AREA)
• Compressor (AREA)

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• 2001
  • 2001-08-08 EE EEP200100415A patent/EE04286B1/xx not_active IP Right Cessation
• 2002
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