EP0093732B1 - Device in a pressure system - Google Patents

Abstract

A positive displacement machine, particularly an internal combustion engine, comprises an oscillating piston connected to a piston pump. The cylinder of the pump is connected through valves to a pressure accumulator and to a substantially pressureless tank for the gas to be compressed. The piston (3) of the motor (1) is integral with at least one piston (7) of a pump (8). The valves (10, 11) of the pump (8) which are possibly comprised of slides are positively actuated by a separate independent motor (25).

Description

The invention relates to a device in a pressure system which has a cylinder-piston arrangement which is connected to a piston pump and has an oscillating piston, the cylinder of the pump being connected to a pressure accumulator and a substantially pressure-free reservoir of the pressure medium via positive-controlled valves, and the piston of the cylinder-piston arrangement is rigidly connected to at least one piston assigned to a pump.

Devices of this type are mostly used to convey pressure media from the storage container under pressure into the pressure accumulator, the pump usually being driven by an explosion motor. In special cases, e.g. B. if pressure from a pressure system is to be built up in another pressure system without there being a transfer of the pressure medium, it also happens that the cylinder-piston arrangement provided for driving the pump is acted upon by a pressure medium.

A device of the type mentioned was z. B. proposed by FR-A-2 306 384. In this case, two pumps are controlled via a rotary slide valve which is driven by a hydraulic motor which acts as a metering device for metering the supply of pressure medium to the pumps, synchronization between the hydraulic motor, the rotary slide valve and the motor / pump system being provided. In this case, a check valve is arranged in the line leading from the pumps to the pressure vessel, which prevents flow from the pressure vessel to the pumps.

The disadvantage of this known device is the very great design effort, which is given by the arrangement of the hydraulic motor serving as a metering device, which also drives a sump pump, a corresponding pressure source must also be provided for this motor.

Furthermore, DE-A-26 48 958 has disclosed a device in which one pump piston is rigidly connected to a piston of an explosion motor and each pump via a valve controlled by a regulator, which is controlled as a function of the conditions in the explosion motor, can be connected to a pressure vessel or can be shut off from it. Furthermore, each pump is connected to a high pressure tank via a check valve, which prevents flow from the high pressure tank to the pump. A throttle is still arranged in each connecting line of the pump.

With the corresponding position of the controlled valve, the pistons of two pumps are acted upon by a pressure medium and drive the two pistons of the explosion motor against one another in order to achieve the corresponding compression. When this is reached, the valve is switched over and the pump is separated from the pressure vessel. After ignition, the pistons of the pump are driven against their rest position and push out the pressure medium, which reaches the high pressure tank via the throttles and the check valve.

The disadvantage of this solution is the very high control effort required to control the valve. In addition, the throttles result in a considerable loss of power, which also leads to an undesirable increase in the temperature of the pressure medium.

Common to both solutions is the fact that each cycle is started from a defined idle position and that the medium in the high-pressure container cannot be exposed to the pump, which means that there is a need for another pressure container to supply the pump, which works in phases as a motor to provide the work necessary to compress the air in the explosion engine.

The aim of the invention is now to propose a device of the type mentioned at the outset which is distinguished by a simple structure and in which a separate starting device can nevertheless be dispensed with.

According to the invention this is achieved in that the piston of each cylinder-piston arrangement is resiliently supported in both directions of movement to form an oscillatory system and the valves of the pump are controlled by a separate motor independently of the position of the piston relative to the associated cylinder of the cylinder-piston arrangement , wherein there is also no functional connection between the cylinder-piston arrangement and the engine and the valves of the pump are connected to the pressure accumulator or to the essentially pressure-free reservoir of the pressure medium by means of connections which can be flowed through in both flow directions.

This results in a very simple construction in which the very complex compensation of the rotating eccentric masses required for crankshafts and eccentric disks is unnecessary. In addition, the positive control of the valves or slide valves of the pump allows them to be used to start the explosion motor by actuating the valves in the same way as in normal operation and thus applying pressure medium coming from the pressure accumulator to the piston of the pump. The pressure medium is pushed out of the pump cylinder by the spring action of the gas cushion compressed in the cylinder of the explosion engine, if an ignition occurs, by the action of the explosion in the cylinder of the engine. In any case, the pistons are connected to each other by the application of pressure medium to the pump and the control of the valves the pump is excited to oscillate, the frequency of which is equal to the frequency of the positive control of the valves.

Due to the effects of the explosions in the cylinder of the engine, the oscillation of the piston arrangement leads the phase of the control of the valves or slide valves, which is driven at a constant frequency, and the pressure medium is pushed out into the pressure accumulator and sucked out of the essentially pressure-free reservoir.

Since the piston of the cylinder-piston arrangement, the z. B. can be formed by an explosion motor, when moving to a dead center to give energy to the spring, which may preferably be formed by a gas cushion, the piston is after reaching its dead center from the energy stored in the spring first in the accelerates in the opposite direction, so that, in contrast to the known solutions, there is an oscillatable system in which, since a flow from and to the pressure accumulator and to the pump is possible in both directions, a constant energy exchange between the pump and the single pressure accumulator is also possible. This ensures that the energy required to compress the explosion motor can be taken from the pressure accumulator and that the energy released by the explosion in the motor can be introduced into the pressure accumulator. This also ensures that the pump or the explosion motor can change their phase position relative to the valves, but cannot fall out of step. So z. B. in the absence of explosions in the engine this is driven by the pump, which then runs as a motor, the energy being taken from the pressure accumulator and the pump, together with the cylinder-piston arrangement, lagging the valves in phase. Without special precautions, this will be the case as long as the pressure in the accumulator is sufficient to overcome the sum of the frictional resistances in the pump and the cylinder-piston arrangement. However, it will of course be ensured that the motor controlling the valves is automatically switched off when a minimum pressure sufficient to start the device is reached.

The ignition in the explosion engine can be carried out in the usual way either by auto-ignition when the critical pressure is reached or by spark ignition, the latter taking place in a known manner depending on the position of the piston.

In terms of design, there are particularly simple conditions if the valves are designed as rotary valves which are driven by a separate motor via a toothed belt drive or a toothed wheel gear.

According to a further feature of the invention it is provided that the control of the valves of the pump takes place via a common cam disk and the tappet controlled by this, resulting in a very simple construction in which the mutual phase position of the valves always corresponds to the predetermined values. In particular, this solution cannot lead to changes in the phase position when the speed of the drive of the valve control changes, as is the case with separate and, for. B. coupled via a belt or chain drive cam discs.

Another solution which is very favorable with regard to the adjustment of the mutual position of the opening and closing times of the two valves of a pump is characterized in that the piston of the cylinder-piston arrangement is connected to the piston of the pump via a straight rod, the free end face of this rod forms the piston surface of the pump if necessary.

In a device according to the invention with a cylinder-piston arrangement designed as an explosion motor, according to a further feature of the invention it is provided that the piston of the cylinder-piston arrangement is connected to two pistons of two pumps via a straight rod, it being particularly advantageous if the pistons of the two pumps are connected to it by means of straight rods of the same design and projecting from both end faces of the piston of the cylinder-piston arrangement, and the inlet and outlet openings of the cylinder housing of the cylinder-piston arrangement are arranged in the central region thereof.

This makes it particularly easy to start the explosion engine by pressurizing the two pumps with pressure medium.

The gas exchange in the cylinder-piston arrangement designed as an explosion engine takes place by utilizing the gas vibrations in the intake and exhaust pipes in the manner that is customary in internal combustion engines, the intake and gas exchange ratios being able to be optimized in a simple manner due to the constant frequency of the piston oscillation is. The gas exchange can also be supported by a blower.

The explosion can be caused by spark ignition, such as in a gasoline engine, by injecting fuel into the highly compressed air, such as in a diesel engine, or by blowing in combustible gas during the compression stroke and then igniting the combustible mixture thus formed as a result of the high temperature which arises during the compression.

A particularly preferred embodiment of a device according to the invention is characterized in that the rods serving to connect the pistons slide into the enclosing guides, each of which has a circumferential annular groove machined into its bore and a radially extending and axially annular groove connected to a fuel line has in the direction of the pump spaced bore, which optionally opens into a further annular groove and that each rod is provided with two axially spaced recesses, preferably circumferential grooves, which produce the connection from the annular groove to the combustion chamber of the cylinder-piston arrangement or from the annular groove to the bore connected to the fuel line at different positions of the piston of the cylinder-piston arrangement.

In this embodiment, combustible gas can flow in through an annular gap which is formed by the annular groove of the rod connecting the pistons closer to the cylinder of the explosion motor, and opens briefly during the compression stroke in order to close the combustion chamber with the annular groove serving as the storage chamber to the bore of the guide connect, from which the flammable gas under pressure flows into the combustion chamber and mixes with the air there. The combustible gas flows at the top dead center of the piston of the explosion motor through a second annular gap formed by the second annular groove of the piston rod into the annular groove of the bore in the guide. This construction has the advantage of a small number of moving parts, since the rod connecting the pistons also controls the fuel supply to the combustion chamber of the explosion engine. The pressure of the combustible gas can be regulated with a suitable valve in order to be able to adapt the inflowing quantity and thus the output to the requirements. The output can be regulated as a function of the pressure in the pressure accumulator in such a way that it increases as the pressure in the pressure accumulator falls and the pressure therefore remains essentially constant regardless of the removal of the pressure medium from the pressure accumulator.

Either gaseous fuel or vaporized liquid fuel can be used as the combustible gas. The evaporation of liquid fuel can either be done by using the exhaust heat in a suitable, thermostatically controlled heat exchanger or by means of a whisk that converts mechanical energy into heat in a small chamber and thereby evaporates the fuel. The whisk can expediently be driven by means of a hydraulic motor or a small turbine acted upon by the pressure accumulator.

• Figur 1 eine Ausführungsform mit nur einer und
• Figur 2 eine solche mit zwei Pumpen pro Zylinder eines Explosionsmotors.

The invention will now be explained in more detail with reference to the drawing, which schematically represents two exemplary embodiments of the invention. It shows

• Figure 1 shows an embodiment with only one and
• Figure 2 one with two pumps per cylinder of an explosion engine.

According to Figure 1, the explosion engine 1 is designed as a two-stroke engine, in which the inlet opening 2 z. B. is connected to a carburetor, not shown. Of course, an injection of fuel would also be possible, with the control of the injection taking place as a function of the position of the piston 3 of the explosion engine. The piston 3 is designed as a flat piston, but a piston provided with a nose can of course also be used. Furthermore, since this is not part of the invention, the usual piston rings have not been taken into account in the illustration for reasons of simplicity.

The exhaust opening 4 in the cylinder housing 5 is connected to conventional silencers or mufflers, not shown.

The piston 3 of the explosion motor 1 is connected by means of the rod 6 to the piston 7 of the pump 8, the cylinder housing 9 of which is axially aligned with the cylinder housing 5 of the explosion motor 1 and connected to the latter, possibly also being formed in one piece with respect to the housing halves.

In the cylinder housing 9 of the pump 8, the piston 7 of which could possibly also be formed by the rod 6 or its free end face, two openings 12, 13 which can be closed by valves 10, 11 are arranged, which are connected via pipes 14, 15 to a reservoir 16 for the pressure medium or a pressure accumulator 17 are connected.

These valves 10, 11 are pretensioned by the springs 18, 19 which hold the valves in the closed position. The valves are controlled by means of the plungers 20, 21 which are held in contact with the cam disk 24 by the springs 22, 23, which in turn is driven by the motor 25. The motor 25, which is preferably designed as an electric motor, has a device, not shown, which ensures that it comes to a standstill only in a certain position of the cam disk 24, in which the valve 11 is securely closed and the valve 10 is kept open. Furthermore, a valve 26 is arranged in the pipeline 15, which closes as soon as the power supply to the motor 25 is interrupted.

In order to avoid the formation of gas cushions on the back of the piston 7, a vent hole 26 is provided in the cylinder housing.

In order to put the illustrated device into operation, it is sufficient to set the cam disk 24 in rotation by means of the motor 25, and to allow the pressure medium to flow into the pump 8 from the pressure accumulator 17 via the opened valve 26 and the valve 11, the valve 10 due to the shape of the cam disc 24 is closed. As a result, the piston 7 is pushed back and the piston 3 compresses the gas cushion located in the cylinder housing 5 after sweeping over the inlet and outlet openings 2, 4. This acts as a spring and drives the two pistons 3 and 7 back after closing the valve 11 and opening the valve 10, which process is due to the rotation of the cam disk 24, the pistons 3, 7 due to the inertia via the inlet - And outlet openings 2, 4 continue to run and there is suction before the fuel mixture prepared in the carburetor, not shown. This mixture is then compressed again as soon as the valve 10 closes and the valve 11 opens and pressure medium flows into the pump 8.

As soon as the frequency of the oscillating movement of the pistons 3, 7 has increased sufficiently due to the increasing speed of the engine 25 or has reached the operating value, sufficient fuel mixture is drawn in and the mixture is ignited during the subsequent compression and the like. between either by ignition due to the reaching of the critical pressure or a spark ignition by means of a device, not shown, which is controlled as a function of the position of the piston 3 or of the pressure in the end of the cylinder housing 5 remote from the pump 8.

If there is an explosion of the fuel mixture, the pistons 3 and 7 are driven back very quickly and before the valve 11 is closed, as a result of which the medium in the cylinder housing 9 is pushed out via the valve 11 to the pressure accumulator 17. In the subsequent, by the compression of the gas cushion locked between the rear side 31 of the piston 3 and the end face of the cylinder housing 5 facing it, which acts as a spring, the pistons 3, 7 are again driven forward, whereby pressure medium from the open valve 10 Storage container 16 is sucked. At the same time, the fuel mixture sucked in by the piston driven back by the previous explosion is compressed again and then brought to ignition.

During the transition from the starting process, in which the pressure medium in the cylinder housing 9 of the pump 8 is released with the release of mechanical work, to normal operation, the speed of the motor 25 driving the cam disk 24 remains constant and it only changes the phase position of the pistons 3 and 7 in relation on the position of the valves 10, 11 or the cam disk 24.

When the device is switched off, it is sufficient to interrupt the fuel supply to the explosion engine 1 and to switch off the engine 25, the latter being able to take place with a slight delay. During the stopping of the motor 25, the oscillation frequency of the pistons 3, 7 decreases to the same extent as the speed of the cam disk 24, ensuring that the cam disk 24 ultimately remains in a position in which the valve 11 is closed, the valve 10, however, is open.

In order to ensure that the pistons 3, 7 are in a position after the device has been switched off and that the device can be started again, a spring 27 is provided which urges the piston 7 to the right, so that it can in no case remain in the left extreme position, in which an automatic start using the print medium would be impossible.

To avoid major damage in the event of a breakdown in the valve control, a spring-loaded safety valve 28 is provided, which allows the pressure medium to flow off if, for example, B. comes to an explosion of fuel mixture in the cylinder housing 5 with simultaneously closed valves 10 and 11 of the pump 8.

The piston 3 of the explosion motor 1 is rigidly connected to the pump pistons 7, 7 'via the rods 6, 6'. This piston arrangement is set in vibration by the pressure oil from the pressure container 17, since this flows into the cylinder housings 9, 9 'via the valves 11, 11', which are designed as rotary slide valves and are driven by a separate motor, not shown, and alternately onto the pump pistons 7, 7 'presses. In the unpressurized period following the printing period, the cylinder housings 9, 9 'are connected to the essentially unpressurized storage container 16 via the rotary slide valves which serve as valves 10, 10' and the liquid is ejected. The gas cushions in the cylinder space 71, 71 'serve as springs and support the alternately loaded pistons 7, 7' of the pumps 8, 8 '.

The ignition of the combustible gas mixture in the cylinder spaces 71, 71 'as a result of the high temperature arising during the compression of the gas cushion leads to an explosion of this combustible gas mixture. Because of the pressure of the explosions in the cylinder spaces 71, 71 ', the piston arrangement consisting of the pistons 3, 7 and 7' leads the phase of rotation of the rotary valves 10, 11 and 10 ', 11' and the pressure medium is pushed out into the pressure vessel 17 and for suction from the essentially unpressurized reservoir vessel 16. The higher the explosion pressures, the more the piston arrangement hurries ahead of the rotary slide valve rotation in phase and the more pressure medium is conveyed into the pressure vessel 17.

When the piston assembly is in the right extreme position, the annular groove 83 connected to a fuel line 82 via a radially extending bore 81 is connected through the annular groove 91 of the rod 6 to a storage chamber which is formed by an annular groove 100 of the guide 101 of the rod 6 and the combustible gas under pressure in the annular groove 83 flows through the annular groove 91 into the annular groove 100.

In the right extreme position of the piston arrangement 3, 7, 7 'there is also ignition of the gas mixture located in the cylinder space 71' to the right of the piston 3, the combustible gas before the right extreme position of the piston arrangement is reached via the annular groove 111 'of the rod 6 'has flowed into the cylinder space 71' from the annular groove 100 'serving as a storage chamber.

If the piston arrangement now moves again to the left as a result of the explosion in the right-hand cylinder space 71 ', the annular groove 111 briefly connects the annular groove 100 serving as a storage chamber to the cylinder space 71 and the combustion Bare gas flows into this cylinder space 71 and mixes there with the combustion air. This gas mixture is now compressed and ignited.

When the piston arrangement moves to the left as a result of an explosion in the right cylinder chamber 71 ', the air which has flowed into the cylinder chamber 71 during the previous movement of the piston arrangement to the right is compressed, and fresh air compressed by the fan 140 after the opening of the inlet opening 2 is released into the cylinder chamber 71' blown in and at the same time the combustion gases are pushed out through the likewise opened outlet opening 4, so that they reach the exhaust manifold 190 via the exhaust pipe 180.

After passing through a certain distance to the left, the annular groove 111 briefly connects the annular groove 100 of the guide 101 of the rod 6 serving as a storage chamber to the cylinder space 71 and the combustible gas flows into the latter and mixes with the combustion air pre-compressed there. This gas mixture is compressed further by the piston 3 moving to the left, the connection between the annular groove 100 and the left cylinder space 71 being closed again by the rod 6 before the left extreme position is reached. The compression of the gas mixture in the left cylinder chamber 71 leads to an explosion of the mixture in the area of the left extreme position of the piston arrangement.

When approaching the extreme left position of the piston arrangement 3, 7, 7 ', the annular groove 83' connected to a fuel line 82 via a radially extending bore 81 'is connected through the annular groove 91' of the rod 6 'to a storage chamber, which is connected by an annular groove 100 'of the guide 101' of the rod 6 'is formed and the flammable gas under pressure in the annular groove 83' flows through the annular groove 91 'into the annular groove 100'. From this, when the piston 3 approaches its right extreme position, it reaches the cylinder space 71 'via the annular groove 111'.

The pressure of the combustible gas in the annular groove 83 is set with the regulating valve 130.

The combustible gas is produced by vaporizing liquid fuel. B. a hydraulic turbine 201 provided whisk 200 is provided, the evaporation is achieved by the mechanical energy introduced into the liquid and the ejection of small liquid particles.

Claims (9)

1. In a pressure system an apparatus comprising a piston cylinder unit (1) which is connected to a piston pump (8) and which has an oscillating piston (3), wherein the cylinder (9) of the pump (8) communicates by way of positively controlled valves (10, 11) with a pressure reservoir (17) and a substantially unpressurised storage container (16) for the pressure medium and the piston (3) of the piston cylinder unit (1) is rigidly connected to at least one piston (7) associated with a pump (8), characterised in that the piston (3) of each piston cylinder unit (1) is supported resiliently in both directions of movement to form an oscillatory system and the valves (10, 11) of the pump (8) are controlled by means of a separate motor (25) independently of the position of the piston (3) relative to the associated cylinder (5) of the piston cylinder unit (1), wherein there is also no functional connection between the piston cylinder unit (1) and the motor (25), and the valves (10, 11) of the pump are communicated with the pressure reservoir (17) and the substantially unpressurised storage container for the pressure medium respectively by way of ccmmunications through which the pressure medium can flow without throttling in both directions of flow.

2. Apparatus according to claim 1 characterised in that control of the valves (10, 11) of the pump is by way of a common cam disc (24) and pushrods (20, 21) controlled thereby.

3. Apparatus according to claim 1 characterised in that the valves are in the form of rotary slide valves (4, 5 ; 4', 5') which are driven by way of a toothed belt drive or a gear transmission by a separate motor.

4. Apparatus according to claim 1 or claim 2 characterised in that the piston (3) of the piston cylinder unit (1) is connected to the piston (7) of the pump (8) by way of a straight rod (6), wherein the free end of said rod (6) possibly forms the piston surface of the pump (8).

5. Apparatus according to one of claims 1 to 4 wherein the piston cylinder unit is in the form of an internal combustion engine, characterised in that the piston (3) of the piston cylinder unit (1) is connected by way of a straight rod (6) to two pistons (7, 7') of two pumps (8, 8').

6. Apparatus according to claim 5 characterised in that the pistons (7, 7') of the two pumps (8, 8') are connected to the piston (3) of the piston cylinder unit (1) by way of identical straight rods (6, 6') which project from both faces of the piston (3), and the inlet and exhaust ports (2, 4) of the cylinder casing (5) of the piston cylinder unit (1) are arranged in the middle region thereof.

7. Apparatus according to claim 6 characterised in that the rods (6, 6') which serve to connect the pistons (3, 7, 7') slide in guides (101, 101') which are disposed around the rods and each of which has a recess provided in the bore thereof, preferably an annular groove (100, 100') extending therearound, and a radially extending bore (81, 81') which communicates with a fuel conduit (82, 82') and which is spaced from the annular groove axially in a direction towards the pump (8, 8'), which bore (81, 81') possibly communicates with a further annular groove (83, 83'), and that each rod (6, 6') is provided with two axially spaced-apart recesses, preferably peripheral grooves (91, 91', 111, 111') which, in various positions of the piston (3) of the piston cylinder unit make a communication from the annular groove (100, 100') to the combustion chamber of the piston cylinder unit (1) and from the annular groove (100, 100') to the bore (81, 81') communicating with the fuel conduit (82, 82'), respectively.

8. Apparatus according to one of claims 5 to 7 characterised in that an agitator (200) which rotates in a chamber is provided for the evaporation of liquid fuel, which agitator is preferably driven by a hydraulic turbine (201) operated by the pressure medium.

9. Apparatus according to one of claims 1 to 8 characterised in that the piston (3) of each piston cylinder unit (1) is resiliently supported by a gas cushion in the cylinder.

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