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
  • F01B11/00—Reciprocating-piston machines or engines without rotary main shaft, e.g. of free-piston type
  • F01B11/02—Equalising or cushioning devices
• • 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
  • F01L25/00—Drive, or adjustment during the operation, or distribution or expansion valves by non-mechanical means
  • F01L25/02—Drive, or adjustment during the operation, or distribution or expansion valves by non-mechanical means by fluid means
  • F01L25/04—Drive, or adjustment during the operation, or distribution or expansion valves by non-mechanical means by fluid means by working-fluid of machine or engine, e.g. free-piston machine
  • F01L25/06—Arrangements with main and auxiliary valves, at least one of them being fluid-driven
• • 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
  • F02B71/00—Free-piston engines; Engines without rotary main shaft
  • F02B71/04—Adaptations of such engines for special use; Combinations of such engines with apparatus driven thereby
  • F02B71/045—Adaptations of such engines for special use; Combinations of such engines with apparatus driven thereby with hydrostatic transmission
• • 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

Definitions

• the invention relates to the operation and control of a free piston aggregate.
• the aggregate in question is a free piston aggregate in which the compression of combustion gas takes place with the aid of a hydraulically moved free piston and in which the free piston mainly supplies hydraulic energy. More specifically, the aggregate in question is the so-called Potma or TP-aggregate, which was first described in the Dutch patent application 68.14405, in which only one piston is used per combustion cylinder and the frequency and power control are realized by keeping the free piston in a stationary position at the end of each expansion stroke during a longer or shorter waiting period.
• the movement of the free piston or, rather, the free piston combination is not a forced movement, such as is the case in a crank-connecting rod engine.
• the combustion piston is connected to the crankshaft and makes a forced harmonic movement, while the movement and timing of the free piston must take place by operation and control of the (combusti ⁇ on)gas and liquid flow, the pressure of which determines the movement of the free piston.
• This operation and control for attaining an optimal movement of the free piston largely takes place by remotely operating certain gas and liquid valves by means of electric control signals going out from the central control electronics.
• the main points here are the quick opening and closing of specific valves with sufficiently large passages that influence specific flows of liquids and gases, which determine the free piston movement and thus also the optimal action of the free piston aggregate.
• a disadvantage of the known free piston aggregates is that hydraulic throttling losses usually occur when some valves do not open or close quickly enough and/or have a passage that is too small. Another disadvantage is that imperfect gas-filling of the combustion cylinder takes place in the known free piston aggregates, owing to the fact that the charging device is mechanically coupled to the movement of the combustion piston, which is not optimal, also in view of the electronically controlled waiting periods of the free piston.
• a third disadvantage is that the known free piston aggregates have a rather intricate conduit and valve configuration.
• a fourth disadvantage is that, in the known conduit configuration of free piston engines, flow and leakage losses occur at the fast-moving pistons and rods and during the waiting periods of the free piston.
• a device for generating a fast movement as described in claim 1 is provided to that end.
• Claims 2 - 9 provide advantageous embodiments for this device.
• a device for generating a relatively large and powerful and, in particular, fast movement, controlled remotely and with very littly energy, which movement can be implemented within a very short period of time after the control signal.
• the movement is mainly used for operating various types of hydraulic and pneumatic valves, either sliding valves or completely sealing seating valves. Each time, the movement is brought about by one or more hydraulically operated adjusting piston(s) .
• the device for the valve operation according to the inven ⁇ tion always comprises a hydraulic adjusting piston, with which the valve disc of the valve that has to be operated is adjusted.
• the fast movement from the initial position to the final position of the valve takes place under the influence of hydraulic (high) pressure on one side of the adjusting piston.
• the high pressure medium flows towards the pressure side of the adjusting piston via a main that, in the initial position, is closed by the adjusting piston itself.
• the adjusting piston must therefore be moved across a very small initial distance in order to open this main.
• This initial movement may take place with mechanical, electromagnetical and electrodynamical means because no (high) pressure is exerted on the two sides of the adjus ⁇ ting piston in the initial position and the adjusting piston can move freely to the extent that, in the case of movement from the initial position, no pressure build-up can occur by displacement of liquid as a result of said movement.
• the initial movement is preferably achieved with hydraulic means under the influence of an electric signal to fast- working electrovalves with a small passage, in which, via a narrow auxiliary channel, pressure medium flows towards the pressure side of the adjusting piston.
• the pressure side of the adjusting piston In the starting position, the pressure side of the adjusting piston is connected with low pressure, as a result of which a pos ⁇ sible leakage flow to said pressure side cannot lead to pressure build-up and unwanted movement of the adjusting piston.
• Claims 10 - 21 offer an application of the device for operating a gas valve for a combustion chamber, and the gas or supply valves and re-setting valves used therewith.
• a method and a device for charging the combustion chamber of a free piston aggregate are provided, as described in claims 22 - 26.
• a method and a device are provided with which the fresh air or gas supply to the combustion chamber is controlled.
• the method and the device are such, that the quantity of fresh gas and thus also the development of the pressure in the combustion cylinder can be operated and controlled remotely, for every stroke, by the control electronics.
• the operation and control of the fresh gas flow towards the combustion cylinder takes place by means of a piston gas pump that is hydraulically driven with the same fre ⁇ quency as the free piston.
• the gas pump piston draws in fresh gas during the final part of the compression stroke of the free piston and/or during the initial part of the expansion stroke. Then, before the beginning of the next compression stroke, the compression of the drawn-in fresh gas in the gas pump cylinder commences. The moment the delivery stroke of the gas piston begins is determined with a control signal from the control electronics to a fast-working hydraulic valve that admits pressure medium to the hydraulic piston that activates the pump piston.
• the gas pump cylinder is connected to the combustion cylinder via a conduit in which a non-return gas valve or an operated gas valve are present.
• the non-return valve opens when the pressure in the gas pump cylinder is higher than the pressure in the combustion cylinder.
• the beginning of the delivery stroke of the gas pump piston is regulated in such a way that the non-return valve opens during the compression stroke of the free piston within a period of time beginning shortly before the exhaust ports of the combustion cylinder close until well before the end of the compression stroke of the com ⁇ bustion piston.
• the gas pressure in the gas pump cylinder can rise considerably higher than the pressure in the combustion cylinder before said valve is opened. The moment of opening is then determined by the control electronics.
• the moment of opening will lie within the indicated period of time, since, when opening takes place well before the exhaust ports close, fresh air or fresh combustion gas will disap- pear through the exhaust ports without having been used, as a result.
• the gas from the gas pump reaches the combus ⁇ tion cylinder via a conduit that debouches in the head or in the cylinder wall of the combustion cylinder.
• the actuated gas valve is opened by an adjusting piston, as described before.
• the moment the delivery stroke of the gas pump commences and ends is principally determined by the operation of the hydraulically actuated valve that controls the supply and discharge to the hydraulic cylinder of the gas pump. By controlling the opening and closing times of this hydraulic valve and of the gas valve, the quantity of supplied fresh air or fresh combustion gas per stroke can be operated and controlled by the control electronics.
• a free piston aggregate is provided such as described in the claims 27 - 53, and a release valve used therewith.
• a specific embodiment is given of the liquid supply and discharge to the first and second displacement space on either side of the hydraulic compression piston of the free piston com ⁇ bination. It involves various conduit configurations with or without non-return valves and/or valves that can be quickly and remotely actuated, with which the movements of the free piston are controlled.
• the attained simplification consists of a limitation of the number of valves and/or a limitation of the number of displacement spaces upto two at the least by integrating the energy and the compression piston, in addition to which the minimally required number of high pressure accumulators can be reduced to two in certain cases.
• the embodiments have the advantage that leakage via rod and piston seals at the hydraulic compression piston is reduced as a result of the fact that the supply of hydraulic medium from spaces with high pressure via con ⁇ duits to the compression cylinder is prevented during the waiting period of the free piston near the lower dead centre with the aid of non-return valves and actuated valves in said conduits.
• This embodiment according to the invention has a great number of variants and examples of application.
• the second displacement space is permanently connected to a space with a pressure that is as low as possible and said second displacement space is therefore never connected to a space with high pressure when the machine is working normally.
• Figure 1 shows a known embodiment of a hydraulic free piston aggregate
• figure 2 shows a single-acting valve actuation with one adjusting piston
• figure 3 shown a double-acting valve actuation with two adjusting pistons
• figure 4 shows a valve actuation with an auxiliary adjus- ting piston
• figure 5 shows a charging of the combustion part of a free piston aggregate with a separate hydraulically driven piston gas pump
• figure 6 shows embodiments of an actuated gas valve in the head or wall of the combustion cylinder
• figure 7 shows embodiments of the supply and discharge of hydraulic medium to the hydraulic compression cylinder of the free piston aggregate
• figure 8 shows a release device for pressure medium in the first and third displacement space of the free piston aggregate
• figure 9 shows an embodiment with two actuated valves to the hydraulic compression cylinder of the free piston aggregate
• figure 10 shows an embodiment with upto two integrated displacement spaces and upto two integrated accumulators.
• Figure 1 shows a known hydraulic free piston engine or free piston aggregate. The way it works is described below.
• the combustion piston 7 moves within the combustion cylinder 15, which combustion piston 7 is connected via rod 35 to the hydraulic piston 8 and to the plunger 9.
• the piston 8 moves within a cylinder 17 and, therewith, forms the first displacement space 1 (with pressure Ptc) and the second displacement space 2 (with pressure Pec) .
• the left- hand annular piston surface of piston 8 is smaller than the right-hand annular piston surface.
• the plunger 9 forms the third displacement space 3.
• the combustion engine portion especially comprises the combustion cylinder 15 and the combustion piston 7 and acts as a two-stroke combustion engine with exhaust- 13 and inlet-channel 14.
• Liquid under high pressure Pea is also supplied from accumulator 4 to displacement space 2 via channel 10.
• the piston 8 comes to a standstill in the lower dead centre (LDC) at the end of the expansion stroke.
• LDC lower dead centre
• the valve 12 In order to start the compression stroke (movement to the left) , the valve 12 must open. The time that passes from the moment the free piston comes to a standstill in the LDC and the moment the starting valve 12 opens and the compressions stroke com- mences, is the waiting period of the free piston. This waiting period is controlled with starting valve 12, and thus the stroke frequency of the free piston is also determined, as well as the quantity of pressurized oil produced per unit of time.
• the free piston Owing to the elasticity of the liquid, the free piston rebounds to the left even before the starting valve 12 opens. During this movement to the left a counterforce is experienced, however, under the influence of the pressure Ptc in the second displacement space 2 that is connected to the accumulator 4. Owing to this counterforce, the free piston comes to a standstill again within a very short period of time, even before channel 19 is released by the piston 8. Subsequently, the free piston moves to the left again, until the pressure in space 1 has risen so much that the piston comes to a standstill. In this way the free piston oscillates with diminishing amplitude near the LDC and finally comes to a complete standstill, especially as a result of frictional losses.
• the high pressure in space 2 is necessary in order to prevent the free piston, under the influence of the elasticity of the oil in space 1 and 3, from rebounding too far upto past the port of channel 19, as a result of which an unwanted new stroke is made and the operation can no longer be controlled with starting valve 12.
• space 2 is under high pressure during the waiting period and oil will leak via the rod seal 16.
• it is difficult to seal properly because of the varying temperatures caused by the proximity of the hot combustion piston to which rod 25 is attached.
• the combination of varying temperatures, extremely high piston speed and high pressure is undesired from a viewpoint of limitation of leakage losses.
• leakage also occurs from ac ⁇ cumulator 4 via channel 19 along the seal between piston 8 and the cylinder wall. Differences in temperature occur less frequently here, but there is a longer leakage gap, however, owing to the larger diameter of piston 8.
• FIG. 2a shows the basic embodiment of the movement device according to the invention.
• the adjusting piston 51 moves within cylinder 72.
• This adjusting piston 51 in the depicted first position or initial position, closes the main 59 in the wall of the cylinder.
• the piston or plunger combination 51 (figure 2b), together with the cylinder 72, forms a first displacement space 61 and a second displace ⁇ ment space 79.
• the piston or plunger combination can move towards the second, most right-hand position and, via rod 28, moves the mass M that mainly consists of a valve slide or valve of an air- or hydraulic piston or a gas valve.
• the first displacement space is connected to low pressure P L .
• the second displacement space 79 is also connected to low pressure P L via a large channel 72a.
• the main 59 is under high pressure Ph.
• the adjusting piston 51 can move from the first position without pressure build-up by displacing hydraulic medium in space 79. After a small first or initial movement to the right the adjusting piston 51 opens the main channel 59, causing hydraulic medium under high pressure to flow in and causing the adjusting piston 51 or the plungers 51 with the mass M to move to the second end position very quickly.
• the means for generating the initial movement are described in the figure descrip ⁇ tion and at figures 2c - 2e, as well as the means to move the adjusting piston back to the first position again.
• FIG. 2 shows a drawing of the movement device according to the invention, which is used for operating a hydraulic valve 96.
• the valve 96 which may serve as starting valve 12 of the free piston aggregate, is operated by the fast-working adjusting piston 51 that moves under the influence of a medium under high pressure that flows in via electrovalve 74 in auxiliary channel 56 and via main 59 that is opened by the adjusting piston 51.
• valve 96 In the initial position valve 96 is closed.
• the main 59 (with large passage) is under high pressure Ph and auxiliary channel 56 is connected to low pressure Pi via actuating valve 73.
• the adjusting piston 51 does not start moving because space 61 is under low pressure and main 59 is closed off and the very slight hydraulic imbalance is compensated by the left seating seal with spring 58.
• valve 68 switches to the left
• Px-Py will become positive (68 switches to the right) at the end of said stroke and during the expansion stroke.
• the main 59 will come under low pressure, after which the adjusting piston 51, under the spring force of spring 83, moves to the left and closes the valve 96.
• the star- ting valve 96 is now closed again.
• control electronics have closed actuating valve 74 and opened 73, causing space 61 to be connected to low pressure.
• valve operation according to figure 2c brings about a fast-working and electrically controllable valve adjust ⁇ ment, in which use can be made of small and very fast-wor ⁇ king electrovalves (73, 74), which may be obtained on the market, and of standard sliding valves (96) .
• port 72a is connected to the pressure Pac in the third displacement space 3 of the energy cylinder of the free piston aggregate and channel 59 is connected to the pressure Paa in the energy accumulator 5.
• the pressure Pac is lower than Paa.
• the adjusting piston 51 can then open valve 96 and, under the influence of the pressure diffe- rence Paa-Pac, will remain in the second position.
• Pac rises to a level that is equal to or higher than Paa, as a result of which the adjusting piston, owing to the spring force and the slight pressure difference present, moves back to the first position during the expansion stroke.
• the time that is required for this back-movement can be influenced by the spring force and possibly by a resistance with, para ⁇ llel thereto, a non-return valve in channel 59 in order to achieve that valve 96 closes shortly before the end of the expansion stroke and, before that moment, maintains a large passage from the first displacement space 1 to the compression accumulator 4.
• valve actuating rod 28 is operated by two adjusting pistons 51 and 52.
• the opening of valve 96 takes place by adjusting piston 51 in a way that corresponds with the one described at figure 2c.
• the adjusting piston 51 opens channel 63 and brings it into connection with the pressure Ph in adjusting cylinder 71, causing re ⁇ setting valve 68 to switch to the right, counter to the spring force of spring 67.
• channel 59 and thus also 63 will be put under low pressure and main 60 under high pressure.
• valve 67 cannot switch valve 68 to the left, however, because non-return valve 65, bridged by the pre-stressed non ⁇ return valve 66, prevents it from doing so.
• the pressure required to open 66 cannnot be generated by spring 67.
• the adjusting piston 52 Owing to the pressure in main 60, the adjusting piston 52 can now move to the left after an electric command from the control electronics of the free piston aggregate, closing electrovalve 73 and opening 76. Valve 96 will now close. This closing takes place by adjusting piston 52 in a way that corresponds with the one described for adjus ⁇ ting piston 51.
• valve 96 which may serve as starting valve 12
• Re-setting valve 68 switches to the left, as a result of which the initial position is reached again.
• Figure 4 indicates how, in the case of a heavy adjusting piston and the mass moved by it, the speed of response of the adjusting piston 51 can be increased by means of an auxiliary adjusting piston 51a. It works as follows.
• Figures 5a-d depict the free piston engine of figure 1 with the charging device.
• the gas supply channel 46 debouches in the head of the combustion cylinder, but channel 46 can also debouch in the wall of the combustion cylinder 15 and be closed off there by the combustion piston 7.
• This embodiment of figures 5c and d entails that the closing of the gas supply from pressure space 137 is now attended to by the combustion piston. This ensures guaranteed, extre ⁇ mely fast closing.
• the supply valve 45 is embodied as an actuated valve 45a (figure 5c) or as a non-return valve 45 (figure 5d) and can now close much more slowly during the period of time that passes from the moment the combustion piston closes off channel 27 until the moment the combus ⁇ tion piston re-opens channel 27 during expansion.
• the exhaust port 13 of the combustion cylinder is also indicated.
• Port 46 with non-return valve 45 or actuated valve 45a, is connected via channel 44 to the charging cylinder 42 within which the scavenging piston 128 moves.
• This piston 128 is connected via rod 119 to the hydraulic piston 121 which moves within the hydraulic cylinder 127.
• the spaces 120, 122 may be connected to high or low pressure.
• Air supply to the charging cylinder 137 takes place via the channel with non-return valve 41, in which the valve 41 is an operated valve or a non-return valve.
• the charging device works as follows. Proceeding from the depicted initial position with the combustion piston 2 in the lower dead centre (LDC) , the combustion piston 7 moves to the left and compresses the gas in cylinder 15 as soon as the exhaust port 13 is closed by the piston 7. Before the moment the combustion piston 7 commences the compres ⁇ sion stroke starting from the LDC, the supply of hydraulic medium under high pressure to the hydraulic cylinder 127 is opened, under the influence of which the scavenging piston 128 moves upwards.
• the scavenging piston 128 can generally compress the gas in the scavenging cylinder faster than the combustion piston 7 compresses the gas in the combustion cylinder, because, among other things, the scavenging piston is comparatively much lighter and/or makes a shorter stroke.
• the gas pressure in the scavenging cylinder 137 can be higher than the gas pressure in the combustion cylinder 15 at the beginning of the compression stroke, causing gas to flow from the scavenging or charging cylinder 137 via non ⁇ return valve 45 into the combustion cylinder 15.
• This gas supply is ended shortly after the scavenging piston has reached the end of its stroke or by the fact that the scavenging piston is brought to a standstill by the clo ⁇ sing of the supply of hydraulic medium to cylinder 127 with the aid of the hydraulic valves present. Subsequent ⁇ ly, the combustion piston 7 continues its movement to the left until the upper dead centre (UDC) is reached.
• UDC upper dead centre
• the scavenging piston must commence its movement to the left before the combustion piston has started its own movement to the left. As a result, the very moment the combustion piston commences there will be an over-pressure present in the scavenging cylinder and gas will flow to combustion cylinder 15 via channel 44, 46. This flow of gas subsequently increases as a result of the quickly rising gas pressure in the scavenging cylinder. After the supply of hydraulic pressure medium into cylinder 127 has stopped, the speed of the scavenging piston will quickly drop to zero, causing the pressure difference between scavenging and combustion cylinder to decrease as well.
• the important aspect of this device is the pos ⁇ sibility to control the amount of supplied air or gas via channel 46 by letting the movement of the scavenging piston to the left take place sooner or later.
• an over-pressure will already have built up in the scavenging cylinder the moment the combus ⁇ tion piston commences and gas will already flow into the combustion cylinder.
• the exhaust port 13 is still open here, the supplied air from the scavenging cylinder will be able to leave the combustion cylinder again via the exhaust port. This is, of course, effective scavenging.
• the remaining volume of air in the scavenging cylinder will be fed under low pressure into the combustion cylinder and participate in the com ⁇ bustion process.
• the scavenging piston commences later, at a moment in time chosen in such a way that the supply of gas is just commencing via conduit 46 the moment the combustion piston closes off the exhaust port, all the air supplied from the scavenging cylinder will be used for charging. If commencement takes place at an even later moment in time, the charging will diminish because the pressure in the combustion cylinder at which supply from the scavenging cylinder takes place, is higher.
• the degree and nature of the charging can therefore be remotely controlled by the control electronics, in addition to which the early start may also result in a comparatively big charging.
• actuating valve 45a in the head or wall of the combustion cylinder, the operation and control of the fresh gas filling of said cylinder is enhanced even fur ⁇ ther.
• the actuated gas valve makes it possible to start the charging piston sooner and to build up the pressure in the pump cylinder 137 further, until approximately the moment the exhaust port 13 closes and the gas valve opens.
• the greater pressure difference between pump cylinder 137 and combustion cylinder 15 will cause the fresh gas to flow to the combustion space more quickly and more gas to be supplied during the very short period of time of 5 - 10 m.sec. that is available therefor.
• said greater pressure difference increases the amount of energy that is required for the charging by the required higher end pressure.
• the opening and closing times of the hydrau ⁇ lic valves 123 - 126 and the gas valve 45a must therefore be optimized by the control electronics in order to attain a mimimal energy demand for each desired air addition via channel 46. This is possible with the charging device according to the invention.
• the hydraulic valves 123 - 126 are used.
• the hydrau ⁇ lic piston 121 can also be embodied as a single-acting or double-acting adjusting piston 51 and 52, just like those in figures 2c, 3, 6g of 6i.
• the valves 123 and 124 can be embodied as a three-way valve that is moved by a double- or single-acting adjusting piston or as two open-close valves that are operated by a single-acting adjusting piston 51.
• the charging piston 128 can also be controlled by a four- way valve moved by a single- or double-acting adjusting piston as described at figures 2, 3, 6g or 6i, for instance.
• the charging device according to the invention can also be used for the supply of fuel.
• fuel is injected on the places indicated with a triangle. Injection im ⁇ mediately into the combustion cylinder is possible too, of course. Injection of fuel into the charging part has the advantage that more time is available for evaporation and mixing before the fuel reaches the combustion cylinder as an air-fuel mixture, together with the charging air.
• Figure 6a shows an embodiment of the supply valve 45a that is to be mounted into the wall of the cylinder.
• One objec ⁇ tion here is the present space 46 in which air or gas remains behind that is brought into contact with the burning gas mixture in the combustion cylinder during the expansion stroke.
• the volume 46 causes a small pressure drop in the combustion cylinder as soon as the port in the cylinder wall is opened. This pressure drop decreases the energetic efficiency of the machine.
• Figure 6b shows an embodiment of the supply valve 45a with a very small dead volume.
• the valve may not open and must then be kept closed by a considerable force on valve stem 28.
• Figure 63 shows an embodiment of the supply valve 45a with a minimal dead volume, a passage that is as large as possible and a light valve disc 45a.
• the valve disc is a ring or band around the outer wall 38 of the cylinder, in which the wall is provided with holes 46 all around, which holes are opened or closed by rotation of the valve disc 45.
• the valve disc too, is provided with holes 36 that correspond with the holes 46 in the cylinder wall 38 when the valve is open.
• the rotation of the valve disc is made possible on account of the fact that it is provided with a cam 37 to which the operating rod 28 is attached. By moving the rod 28 back and forth, the valve disc is rotated.
• ring 45a it must consist of two parts that are connected to each other after they have been placed in a slot around the combustion cylinder. If a band is used, it must have a joint that is bridged by spring tension or by a fixed connection.
• Figure 6d shows how the band-shaped valve disc can be locked up between two annular sealing surfaces 38 and 39.
• the divided band can now have a light-weight construction and will be able to contact the outer sealing area 39 when there is pressure in the combustion space, and be able to contact the inner sealing area 38 when there is pressure from outside the combustion cylinder (in the pressure space that encloses the outer side of the combustion cylinder here) .
• the surface 39 has holes 35 that corres- pond with the holes 46.
• Figures 6e - 6i relate to the hydraulic valve control.
• the supply valve 45a can also be operated mechanically in a way that is customary for crankshaft combustion enginges, with rotary cams, the movement being transferred to the valve disc mechanically or hydraulically.
• valve operating times of a few milliseconds are necessary here.
• Major forces occur as a result, which preferably should be generated by hydrau- lically operated adjusting cylinders.
• the fast movements do call for comparatively large adjusting pistons, high hydraulic pressures, large passages, while electric or mechanical control valves are necessary that are light to operate and work fast.
• valve controls according to the invention described in the following, is used.
• the valve controls in figures 6e and 6f are, on account of the constructive adaptation and the necessary fast opening and fast closing, rather meant to be mounted in the upper area of the cylinder head, while the figures 6g - 6i show valve controls that are more suitable for valves that are placed in the wall of the combustion cylinder.
• Figures 6e and 6f show the usual embodiment of a spring- loaded sealing gas valve in the head of the combustion cylinder.
• the valve stem 28 is moved by two adjusting pistons 51 and 52, in a way as described at figure 3.
• the opening of the valve is commenced with the aid of the fast little elec- trovalves 73 and 74.
• the pressure medium can now flow in, on account of which the first adjusting piston 51 opens the valve 45a with considerable force and high speed.
• Channel 63 is connected to the first displacement space 61 with high pressure by the first adjusting piston, while channel 64 is connected to the space 79 with low pressure by the second adjusting piston 52. This will cause the re-setting valve 68 to move quickly to the right. As a result, the pressure in the first displacement space 61 decreases via main 59 and the pressure in the second displacement space 62 increases via main 60 and the pressure in the displacement space 53 of the holding cylinder 89 increases via channel 70.
• the second displacement space 62 is connected via auxiliary channel 57 to low pressure and the connection between main 60 and the second displacement space is closed off by the second adjusting piston as well.
• the valve disc 1 is now kept open by the pressure in the holding cylinder 89, opposing the spring force of spring 55, while the first and second displacement spaces are connected to low pressure and the first and second adjusting piston do not exert a resulting force on the valve disc 1.
• a stable open or second position of the supply valve 1 is obtained with this.
• the closing of the supply valve is subsequently started with the aid of electrovalves 73 and 76.
• Valve 73 is closed first, after which 76 is opened. This causes main 60 to be opened by the second adjusting piston 52, after which the valve disc moves to the left with great force and speed.
• channel 64 is connected to the high pressure in the second displacement space 62, while channel 63 is connected to the low pressure in space 79 via non-return valve 66.
• the re-setting valve 68 switches to the left as a result and the initial position is reached again.
• Figure 6f shows an embodiment with a small first adjusting piston 51 and a larger second adjusting piston 52.
• the first displacement space 61 is brought under pressure by closing valve 73 and then opening valve 74, starting from the position depicted in the drawing.
• the first adjusting piston starts off the initial movement to the right and, after a slight displacement, opens the main 59 after which the first adjusting piston quickly reaches the second end position.
• channel 63 is connected to the high pressure in displacement space 61 and channel 64 is connected to the low pressure in space 79, causing the re-setting valve 68 to switch to the right.
• Main channel 60 is now brought under high pressure, so that after the closing of valve 75 and the opening of valve 76 the closing movement of supply valve 1 will commence.
• the permanent high pressure in displacement space 61 and the force to the right that the first adjusting piston continues to exert are unable to prevent the closing movement from taking place because the piston surface of the second adjusting piston 52 is larger than the surface of 51.
• channel 64 When the closed position is reached, channel 64 is brought under pressure and channel 63 is connected to the low pressure space 79, causing the re-setting valve 68 to switch to the left and return to the depicted position.
• Valve 73 is open then, and 74 is closed so that a stable closed position of the supply valve 1 is attained.
• the embodiment according to figure 6f has a disadvantage as compared to that of figure 6e in that there is a larger adjusting cylinder and it has the advantage that there is a simpler re-setting valve and no holding piston.
• Figure 6g shows an embodiment that corresponds to the embodiment of figure 6e as far as its operation is con ⁇ cerned. In this case there is no holding piston 89 because the band or ring-shaped valve member 1 stays in any position when the operating force is cut off. Another difference is the operation of the re-setting valve 68.
• the re-setting valve is operated by pressure dif ⁇ ferences that occur in the displacement spaces of a free piston aggregate. Operation as indicated in figure 6e is possible here as well, however.
• valve 68 does not switch until the pressure dif ⁇ ference Px-Py has reached a certain threshold value.
• Figure 6h shows a valve embodiment with a very small dead space 46 in accordance with what is stated at figure 6.
• a first adjusting piston 51 is present that is larger than the counterforce piston 81 and can therefore quickly open the adjusting piston (opposing the action of the counterforce piston) in accordance with the procedure described above.
• oil flows under high pressure via channel 65 to the operating cylinder of the non-return valve 68, which will switch to the right as a result. This will cause the pressure in the main 59 and in the first displacement space 61 to fall out.
• the first adjusting piston will now move to the right (to the closed position) under the influence of the counterforce piston 81.
• an adjustable restriction 84 might be necessary that slows down the flow into counterforce cylinder 80.
• the re-setting valve 68 may also be operated by pressure differences that occur in the free piston aggregate as described at figure 6g. In that case, non-return valve 82 and the adjustable restriction 84 are unnecessary and the conduits 65 and 87 are left out. Valve 1 will open quickly and will not close until re-setting valve 68 has been switched by the external pressures Pec, Ptc and Pea.
• Figure 6i shows an embodiment in which, just as in figure 6h, only a first adjusting piston 51 is present to quickly open the band-shaped supply valve 1, also indicated in figure 6d.
• the electrovalves 73 - 76 may also be replaced by mechanically operated valves that are moved by a rotary cam.
• the described control of the supply valve 45a with the aid of a first and/or second adjusting piston can also be used for controlling other gas or liquid valves or valves that form a part of known crank shaft or free piston engines.
• control in figures 6e and 6f can also be used for the electrohydraulic operation of inlet and exhaust valves of known two-stroke and four-stroke engines.
• the valves can then be opened and/or closed very quickly and be controlled by the electronics, the camshaft being left out.
• one re-setting valve can operate several adjusting cylinders.
• figure 6j shows the known pos ⁇ sibilities. 140 and 146 are restrictions that are adjus- table or not
• valve 45 is preferably placed in the wall of the combustion cylinder. A closing time then runs from the moment the combustion piston port in the cylinder wall closes off until the moment said piston re-opens the port.
• FIG. 7a A first embodiment thereof is shown in figure 7a, in which the dotted line indicates the non-return valve 107.
• This valve offers passage to compression accumulator 4 via the port in the cylinder wall and channel 19, but prevents the flow of liquid from accumulator 4 to the port in the cylinder wall and, therewith, leakage via the piston sealing to the first displacement space 1.
• the liquid during the entire compression stroke, will only be able to flow to the first displacement space via the starting valve 12.
• starting valve 12 must be dimensioned more largely and may not close until after the UDC.
• Figure 7a also shows a drawing of a second embodiment according to the invention.
• the combustion portion has been left out because, in figure 7a and those following, it is the same as the one in figure 1.
• the second displacement space is connected to accumulator 4 via channel 10.
• a non-return valve 26 is accommodated that only offers passage to the accumulator, but that blocks the flow from the accumulator to the second displacement space and, therewith, also leakage loss via channel 10 and the rod seal 16.
• the embodiment is also characterized by the connection between the first and second displacement space via chan ⁇ nel 29, in which a non-return valve 27 is accommodated that only offers passage in the direction of the second displacement space 2.
• Channel 29 connects the right part of space 1 with the left part of space 2 and has a connec ⁇ tion via channel 28 with a port in the wall of the hydraulic cylinder 17 that is closed by piston 8 during the final part of the expansion stroke and the first part of the compression stroke. (Channels 19 and 28 are not interconnected via the ports in the wall of the cylinder 77) .
• a combination with the non-return valve 107 described above, will cause the leakage during the waiting periods to become low because, during said waiting period, both the high pressure accumulators 4 and 5 are closed and the pressure in the displacement spaces can fall to the minimum level P L .
• the compression stroke commences and moves the free piston to the left. While doing so, the liquid in the second displacement space 2 is pressed to accumulator 4 under high pressure. As soon as the piston 8 opens the port of channel 28 in the wall of the cylinder 17, the liquid can flow from the second displacement space to the first displacement space via a large channel 28, 29. Therefore, in the presence of channel 28, non-return valve 27 may be small.
• Figure 7b shows an embodiment of the hydraulic portion of the free piston engine in which channel 28 as in figure 71 has been left out.
• the non-return valves 26 and 27 must have greater dimensions here. For the rest, the operation and the technical effect are comparable to the embodiment of figure 7a.
• Figure 7c shows an embodiment of non-return valve 27, 30 or 11, in which the closing force of the valve may be enhanced hydraulically.
• a piston 90 is pre ⁇ sent, which will exert a force onto valve disc 93 in the closing direction of the non-return valve when there is pressure difference over said piston.
• Space 98 is con- nected to the discharge channel 29 of the non-return valve. As long as space 104 is kept at the same pressure level as 98, only the valve spring provides the per ⁇ manently present closing force.
• Enhancement of the closing force is activated during the final part of the expansion stroke.
• the fast closing decreases the springing back of the free piston after the LDC because the pressure fall in spaces 1 and 3 commences earlier.
• Enhancement of the closing force according to the invention is a general ⁇ ly usable means for fast closing non-return valves with nevertheless little flow losses.
• the enhancement of the valve force is necessary in the indicated embodiments according to the invention.
• the activation of the enhancement of the closing force takes place by connecting space 99 to a level of low pressure with the aid of electrically or hydraulically operated valves or by connection to a point of the conduit system at which the development of the pressure already follows the desired pattern, as is described at figures 7f and 7g, for instance.
• Figure 7d shows an embodiment of the hydraulic portion of the free piston engine in which space 2 is permanently connected to a pressure accumulator 33 in which there is a pressure Pm that is lower than Pea but high enough to prevent cavitation in space 2 during the expansion stroke. Owing to the fact that Pm is lower than Pea, the leakage via the rod seal 16 will decrease as well. At the same time, however, a stronger spring-back of the free piston with respect to the embodiment according to figure 1 will take place. In order to overcome this drawback, a release valve is suggested in the embodiments according to the invention, which release valve is described at figures 8a and 8b.
• the enhancement of the closing force may be easily ob ⁇ tained here for valve 27, by connecting space 104 of figure 7c to main 60 of figure 3.
• space 104 of figure 7c may be connected to low pressure during the closed position of the starting valve 12 and said closed position only occurs during the final part of the expan ⁇ sion stroke and during the waiting period, also the enhan ⁇ cement of the closing force will be active during said period.
• Figure 7g shows an embodiment in which channels 19 and 28 have been left out and displacement space 2 is permanently connected to accumulator 105 with pressure Pm. It should be noted that the non-return valve 32 to accumulator 5 has been left out here too. This means that enhancement of closing force must be applied for valve 30.
• the control of the enhancement of the closing force may here be obtained by connecting space 104 of figure 7c to channel 94 of figure 7g with a port in the cylinder wall 17, or to main 60 of figure 3. Owing to the fact that channel 94 is only connected to the lower pressure Pm during the righthand position of the free piston, the hydraulic enhancement of the closing force is only active during that time.
• Figure 8a shows a drawing of the signaller for a release valve 100 in figure 8b.
• This release valve is necessary because the pressure in displacement space 2 to Pm has been decreased, which may cause the spring-back of the free piston to increase too much.
• the signaller works as follows. Piston 90 is connected to the valve disc 93 of the non-return valve of figure 7c. The spring-mounted pin 106 breaks off the connection with piston 90 just before non-return valve 93 closes. The free piston then still moves to the LDC and will come to a standstill at a known period of time after pin 106 has broken off the contact with piston 90. Breaking off the contact with the pin 106 that has electrically insulated bearings entails the breaking of the electric contact of point 109 with mass.
• the control electronics convert this signal into a starting signal for the release valve, taking correction data, if any, into account.
• This starting signal arrives at exactly the right moment when, as a result of the opening of the release valve 100 on time, the liquid pressure in displacement spaces 1 and 3 has fallen to P L the moment the piston comes to a standstill in the LDC. Spring-back no longer takes place then and the problems connected therewith stay away.
• FIG 9a an embodiment of a free piston aggregate with valve kl is given. It works as follows. In the depicted position the starting valve 12 and valve kl are closed and the free piston is located at the expansion-end position near the lower dead centre. In order to start the free piston 8, both the starting valve 12 and valve kl are opened. Pressure oil now flows via the starting valve into the first displacement space 1 and from the second displacement space 2 into the compression accumulator 4 via valve Kl. During the first part of the expansion or energy stroke to the right, pressure oil flows from the first displacement space 1 via the starting valve 12 and via non-return valve 11 into the compression accumulator 4, while pressure oil flows from the first displacement space l into the second displacement space via non-return valve 27. Shortly before the end of the expansion stroke (in the position indicated by the dotted line) valve kl and starting valve 12 are both closed.
• the hydraulic medium flows from the first displacement space 1 via non-return valve 11 into accumulator 4 and pressure medium flows from the first displacement space 1 via non-return valve 27 into the second displacement space 2 until the free piston 8 comes to a standstill in the lower dead centre.
• conduit 10 has been added to embodiment 9b again. This has been done for the purpose of preventing high rises in pressure in the first displacement space during the spring-back of the free piston.
• non ⁇ return valve 26 has been introduced.
• non ⁇ return valve 11 on its own, or 11 and 27 may also be brought about with an actuation in conformity with figure 2c or 2d, while the re-setting valve 68, however, is operated via channels in the wall of the adjusting cylinder in accordance with the operation of re-setting valve 68 in figures 6h and 6i.
• valves 11 and 27 work as normal non ⁇ return valves, offering passage from space 1 via conduit 24 into accumulator 4 via conduit 23 and into space 2 via conduit 29, respectively.
• the combined valve in figure 9e holds all the valves shown in figures 9b and 9c.
• the non ⁇ return valves 11 and 27 may also be placed one after the other and as shown in figure 9f.
• figure 10a which has been derived from the embodiment according to figures 7a and 7b, liquid is pressed into the energy accumulator 5 during the compression stroke with a pressure Paa that is higher than Pea.
• the compression pressure Pea is the lowest system pressure and is kept as low as possible by giving piston 8 a relatively large diameter.
• All the energy given out by the combus ⁇ tion gases to the free piston is supplied to the compres ⁇ sion accumulator 4.
• the energy users are connected between Paa and Pea.
• the pressures Pea and Paa are basically constant.
• Pea is lower than Paa.
• Paa and Pea are equal and high.
• the pressure ratios are determined by the difference between the left- and righthand piston surface of piston 8. Pressure Pm is so high that cavitati- on in the second displacement space still cannot take place during the expansion stroke.
• the pressure level Paa is basically constant but may be increased in 10b by partial supply from space 2 during the compression stroke via conduit 38.
• Figures lOd and lOe show an embodiment in which the func- tion of the first and third displacement space is integra ⁇ ted.
• Paa is equal to or higher than Pea depending on the fuel supply.
• the users are connected between 4 and 5.
• Figure lOd has been derived from the embodiment according to figures 7d and 7g, while the embodiment lOe has been derived from figures 7a, 7b, 7e and 7f.
• the stroke volume of the second displacement space can be kept relatively small and Pm can be kept relatively low by using the release valve of figures 8a and 8b.

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)
• Fluid-Pressure Circuits (AREA)

Applications Claiming Priority (9)

Publications (1)

Family

ID=27483683

Family Applications (1)

Country Status (4)

Families Citing this family (11)

Family Cites Families (5)

• 1996
  • 1996-04-10 EP EP96908391A patent/EP0839265A1/de not_active Ceased
  • 1996-04-10 CA CA 2217864 patent/CA2217864A1/en not_active Abandoned
  • 1996-04-10 WO PCT/NL1996/000157 patent/WO1996032576A1/en not_active Application Discontinuation
  • 1996-04-10 AU AU51638/96A patent/AU5163896A/en not_active Abandoned

Non-Patent Citations (1)

Also Published As

Similar Documents

Legal Events