DE102008063730A1 - Internal combustion engine - Google Patents

Abstract

The injection unit has a high pressure line (58) that is assigned a pressure booster (62) with a large active surface and a small active surface, where the larger active surface is impinged by a gas pressure in a combustion chamber (38) and the smaller active surface limits a high pressure chamber (78), to which the high pressure line is connected. An independent claim is included for an internal combustion engine with a piston section.

Description

The The invention relates to an injection unit for an internal combustion engine according to the preamble of claim 1 and an internal combustion engine with such an injection unit.

Internal Combustion Engines usually have at least one cylinder in which a a combustion chamber limiting engine pistons out is. In conventional internal combustion engines are the engine pistons in operative connection with a crank mechanism, via which transmit the piston movement to a driven aggregate becomes. However, the internal combustion engine can also be used as a free-piston engine Be executed in the place of a crank mechanism Hydraulic circuit downstream of a pump as a drive train is. The engine piston is connected to a hydraulic cylinder, via the translational generated during a motor cycle Energy without the classic detour via the rotational movement a crank mechanism fed directly to the hydraulic working fluid becomes. The downstream storable hydraulic circuit is designed to pick up, cache, and store the work being dispensed depending on the power requirements of a hydraulic drive unit, for example an axial piston machine feeds.

The basic structure of such free-piston engines is for example in the DE 40 44 591 A1 or the DE 101 20 196 A1 described so that reference is made to these documents with regard to constructive details.

at conventional internal combustion engines, in particular Diesel internal combustion engines become fuel with high pressure injected into the combustion chamber. For high pressure application of the fuel while high pressure pumps are used, the indirect or driven directly by the crankshaft. Depending on the design The classic internal combustion engines can do the fuel injection doing so via a series injection pump, a distributor injection pump, a Common Rail System, a Pump-Nozzle-System or a Pump-Line-Nozzle-System (Unit-Pump-System) take place, these fuel injection systems relatively complex are constructed. These are executed with a crank mechanism Internal combustion engines are usually also with a variety of cylinders running, so the effort makes sense for the injection systems. In free-piston machines the application of the above-mentioned injection units is relative consuming, because due to the lack of crank mechanism an additional Drive for the high-pressure fuel pump can be provided would have and usually only one cylinder available is. In addition, the efficiency in use of common-rail systems in free-piston engines compared to conventional internal combustion engines lower because of the losses are considerably by the separate drive of the injection unit.

In contrast, the invention has the object, an injection unit and a running with such an injection unit Internal combustion engine to create, where the fuel injection with low device complexity and comparatively good efficiency is possible.

These The object is achieved by an injection unit with the features of claim 1 or an internal combustion engine with the characteristics of the sibling Claim 17 solved.

The Internal combustion engine has at least one in a cylinder guided engine piston, which limits a combustion chamber, in which fuel can be injected by means of an injection unit, wherein this is acted upon by a high pressure line with high pressure the injection unit is supplied. According to the invention in the high-pressure fuel flow path of the injection unit Pressure intensifier with a large effective surface and a small effective area provided, with the larger Acting surface acted upon by the pressure in the combustion chamber is and the smaller effective area delimits a high pressure room, to which the high pressure line is connected.

at the injection unit according to the invention is the Pressure in the combustion chamber exploited to overflow the fuel the pneumatic / hydraulic pressure booster with high pressure to act on. In such a system can thus on a expensive high-pressure pump are omitted, so that the inventive Solution can also be used with free-piston machines without crank drive is. By eliminating the very expensive high-pressure pump leaves the injection unit comparatively with high hydraulic efficiency realize cost-effective.

According to the invention it is preferred if the injection unit opens with a high pressure chamber towards the opening Low-pressure inlet valve is designed for feeding of pressurized fuel in the high-pressure space connected to a low pressure line. It flows in Pressure relief of the pressure booster via the low-pressure inlet valve Fuel from the low pressure line in the high pressure chamber. At the following compression stroke of the engine piston of the combustion cylinder the fuel is then subjected to high pressure.

According to one Embodiment is the injection unit of the internal combustion engine is executed with an injection valve when it reaches the pressure applied via the pressure booster high pressure opens the fuel flow path toward the combustion chamber.

at An embodiment of the invention is the high pressure to be acted upon fuel via a low pressure line and a low pressure inlet valve is supplied.

at a variant of the invention is the pressure booster associated with an injection valve when a predetermined High pressure opens.

at An alternative solution is the injection nozzle integrated into the pressure intensifier. Here is a pressure booster piston designed as a hollow piston, in the back one immersed housing fixed pump piston. In the pressure booster piston Furthermore, an injection nozzle body is guided, the together with the stationary pump piston and the hollow piston the limited initially high-pressure space, out of the case when lifting of the injector body fuel injected can be.

at this variant of the invention is in kinematic reversal of the hollow piston designed as a cylinder, compared to the fixed Pump piston is displaceable. In addition, the high pressure room through the injector body also guided in the hollow piston limited, in its basic position in a closed position is biased and upon reaching a predetermined high pressure in the High pressure chamber is brought into an open position, in the high-pressure fuel into the combustion chamber is injected.

there it is preferred if the injection nozzle body at a distance to its the high-pressure chamber sections limiting End face is provided with a collar, through the one Front-side seat separated from a high-pressure side annulus is, the latter having a pressure relief valve with the low pressure line is connectable.

at This variant, it is advantageous if the high-pressure side annulus and the high-pressure chamber via a nozzle bore with each other are connected so that when resting on his valve seat injector body in the high pressure side annulus and in the high pressure chamber in the closing direction the same pressure works.

This Annular space can be used as spring space for an injector body executed in the closing direction biasing spring be.

at a development of the invention is that of the injector body limited seating space via a connecting duct with the High pressure room connected, the closing in the direction of High pressure applied active surfaces larger are the active surfaces effective in the opening direction, so that the injector body when closed Pressure relief valve biased into its closed position is.

at An embodiment of this variant are in one Pressure intensifier piston bottom nozzle bores formed, which open into the aforementioned seat-side seating space and through it when lifting the injector body high-pressure fuel into the combustion chamber is injected.

at a very compact embodiment executed is the opening stroke of the pressure booster piston by running the guided in this injector body limited to the pump piston, in which case the injection nozzle body is returned to its closed position.

The Connection of the high pressure side annulus and / or the high pressure chamber to the fuel supply can for example via a flexible line, the axial stroke of the pressure booster piston allowed.

at an alternative variant is the connection to the fuel supply in sections along a guide gap between the pump piston and the pressure booster piston.

One Pressure booster piston of the intensifier can over a spring or the low pressure in the high-pressure chamber in the direction of a Basic position.

to The injection quantity can be limited by the stroke of the pressure booster piston be bounded on both sides by stops, so that at a Druckübersetzerhub always about the same Fuel quantity is subjected to high pressure.

These Attacks can change the Fuel quantity to be made adjustable.

at a third embodiment of the invention the injection unit limits the high-pressure side effective area the pressure booster a piston chamber of a pump-nozzle unit. This piston chamber can be electrically controlled via a Shut-off valve for injection with an injection nozzle or to promote low pressure acted upon Fuel connected to a tank.

Of the inventive internal combustion engine is with a Injection unit according to the previously described Configuration executed.

at a particularly compact solution is the pressure booster at least partially recorded in a cylinder head of the cylinder.

Of the Pressure booster can with a hollow or stepped piston be executed, the at least partially in one Guide bore of the cylinder head is guided.

One Piston section with smaller piston area can at a Such solution in an attached to the cylinder head Submerge the pressure intensifier housing, in sections limited the high-pressure chamber of the injection system.

One Another advantage of the solution according to the invention is that the injection time is always the same, because the injection valve opens at a predetermined high pressure to the combustion chamber and this predetermined high pressure over the pressure booster correlated with the compression pressure in the combustion cylinder.

The Invention can be particularly advantageous in a free-piston engine realize.

According to the invention it is preferred if the fuel is diesel fuel.

other advantageous developments of the invention are the subject of further Dependent claims.

in the Below is a preferred embodiment of Invention explained in more detail with reference to schematic drawings. Show it:

1 the basic structure of a free-piston engine;

2 an injection unit of the free-piston engine 1 ;

3 A second embodiment of an injection unit, wherein the injection valve is integrated and

4 the embodiment according to 3 when injecting.

The 1 shows a schematic representation of a free-piston engine 1 as he is for example in the DE 101 20 196 A1 is described. Of course, other types of free-piston engines or conventional internal combustion engines with crank mechanism can be performed with the injection unit described in more detail below.

The illustrated free-piston engine 1 has a motor housing 2 , in its combustion cylinder 4 an engine piston 6 is guided. This is in operative connection with a coaxially arranged hydraulic piston 8th that in an axial bore 10 is guided. An annular end face 12 of the hydraulic piston 8th limits a working cylinder 14 while the larger frontal area 16 of the hydraulic piston 8th a compression piston 18 limited.

In the working cylinder 14 open a pressure channel 20 and a low pressure channel 22 , The latter is with a low-pressure accumulator 24 connected, wherein a pressure medium flow from the working cylinder 14 to the low-pressure accumulator 24 through a check valve 26 is prevented.

The compression cylinder 18 is via a high pressure channel 28 with a high-pressure accumulator 30 connected, the high-pressure channel 28 via a start valve 32 is on or zuusteuerbar. The pressure channel 20 flows into the high-pressure channel 28 one. About another check valve 34 is a flow of pressure medium from the high-pressure accumulator 30 in the working cylinder 14 prevented.

The combustion cylinder 4 is with an exhaust duct 36 provided, via the exhaust gas from that of the engine piston 6 limited combustion space 38 can be dissipated.

The hydraulic piston 8th facing rear of the engine piston 6 limits an inlet space 40 , which has its minimum volume in the illustrated dead center position of the engine piston. The inlet space 40 is through an overflow channel 42 with the combustion chamber 38 connected.

The fresh air can during the compression stroke of the engine piston 6 via an inlet channel 44 with an inlet valve 46 be supplied. The ignition of the free-piston engine is then carried out by injecting fuel through one in the combustion chamber 38 opening injection unit 48 ,

To initiate a compression stroke, the start valve 32 opened so that the high-pressure accumulator 30 with the compression cylinder 18 connected is. By the on the larger face 16 acting pressure, the hydraulic piston is accelerated out of its dead center and this acceleration on the engine piston 6 transfer. That in the working cylinder 14 located pressure medium is via the check valve 34 and the pressure line 20 back to the pressure channel 28 promoted. The face 16 and the ring end face 12 of the hydraulic piston 8th are with the pressure in the high-pressure accumulator 30 acted upon, so that the surface of the piston rod corresponding end face in the direction the outer dead center AT is effective. The connection to the low pressure accumulator is through the check valve 26 shut off. During the compression stroke of the engine piston 6 Fresh air is introduced through the inlet duct 44 and the opened inlet valve 46 sucked into the enlarged inlet space. The acceleration of the engine piston takes place against that in the combustion cylinder 38 Polytropically increasing compression pressure of the fresh air. This will cause the engine piston 6 slowed down and comes to a halt in the outer dead AT.

As a result, fuel is injected through the injection unit 48 injected and ignited by the high temperature of the compressed fresh air, leaving the engine piston 6 is accelerated by the building up combustion pressure in the combustion chamber from the AT towards IT. This acceleration is on the hydraulic piston 8th transferred so that it moves toward its inner dead center IT in. Due to the resulting enlargement of the annular space of the working cylinder 14 Pressure medium is sucked in via the low-pressure channel and the check valve from the low-pressure accumulator. Parallel to this, the pressure medium in the compression cylinder 18 in the high-pressure channel 28 displaced and the hydraulic accumulator 30 charged.

During the return movement build the engine pistons 6 and the hydraulic piston 8th their kinetic energy against the accumulator pressure in the high-pressure accumulator 30 until they are slowed down in IT. During this process the combustion cylinder becomes 38 through the overflow channel 42 from the inlet room 40 overflowing fresh gas flushed - the free-piston engine 1 is ready for the next cycle.

An embodiment of an injection unit 48 is determined by the 2 explained in more detail, the combustion chamber side part of the internal combustion engine 1 with the injection system 48 in an enlarged view shows. Accordingly, the combustion space 38 through the engine piston 6 , the peripheral walls of the combustion cylinder 4 and a cylinder head 50 limited. In the peripheral walls of the combustion cylinder 4 are cooling channels 52 provided, which are flowed through by a coolant, preferably water. The injection unit 48 has an injector 54 , its injection nozzle opening 56 in the combustion chamber 38 empties. The fuel supply to the injector 54 via a high-pressure fuel line 58 connected to a pressure port 60 a pressure intensifier 62 connected. In the illustrated embodiment, the pressure booster 62 in sections in the cylinder head 50 integrated or attached to this. The pressure intensifier 62 has a pressure booster piston 64 acting as a differential piston with a larger piston area 66 and a relatively smaller piston area 68 is executed. The area ratio of the piston surfaces 66 . 68 is dependent on the applied high pressure in the high pressure line 58 and from the pressure in the combustion chamber 38 selected. The structure of the injector 54 corresponds approximately to that of a nozzle holder of a unit-pump (UP) injection system, such as under www.motorlexikon.de is described, so that further explanations are unnecessary.

One of the big piston surface 66 limited piston section 70 is in a pilot hole 72 in the cylinder head 50 guided. The smaller piston area 68 forming piston rod section 74 passes through the guide hole 72 and dives sealingly into a pressure booster housing 76 one, the cylinder head 50 is set and its interior in the guide hole 72 opens. The front-side piston surface 68 of the piston rod section 74 and the right end portion of the intensifier housing 76 limit a high pressure room 78 , in which also the pressure connection 60 opens. The high pressure room 78 also has a low pressure connection 80 to which a low-pressure line 82 is connected, wherein in the low-pressure fluid flow path in the direction of the high-pressure chamber 78 opening low pressure inlet valve 84 is provided. The low pressure line 82 is connected to the fuel tank or to the pressure port of a prefeed pump, via the diesel fuel z. B. under a pressure of 4 bar in the direction of the high-pressure chamber 78 is encouraged.

As 2 is removable, the larger piston area 66 of the pressure booster piston 64 from the pressure in the combustion chamber 38 applied.

Such fuel injection valves have a valve needle, which is biased in the direction of a closed position in which the injection nozzle opening is shut off by the valve needle. The latter is also designed with an active effective in the opening direction effective area, with the pressure at the inlet of the injection valve - in the present case with the pressure in the high pressure line 58 - is charged. When a predetermined high pressure is exceeded, the valve needle is lifted against the force of the biasing spring, so that the fuel with the appropriate high pressure through the injection orifice (s) through into the combustion chamber 38 is injected.

In the basic position (engine pistons 6 in IT) is the pressure booster piston 66 biased by a bias spring, not shown, with a very low spring rate or by the low pressure in the direction of its inner dead center, in which the volume of the high-pressure chamber 78 is maximum. This inner Dead center is by a stop, not shown, for the pressure booster piston 64 Are defined. During the subsequent compression stroke of the engine piston 6 becomes - as described above - the air in the combustion chamber 38 compressed, so that according to the large piston area 66 of the pressure booster piston 64 acting pressure increases and the fuel in the high pressure chamber 78 and in the high pressure line 58 according to the area ratio of the piston surfaces 66 . 68 is subjected to a higher pressure than it is in the combustion chamber 38 is applied.

With increasing stroke of the combustion piston 6 also increases the fuel pressure in the high pressure line 58 and thus at the inlet of the injection valve 54 at. Upon reaching the injector 54 set injection pressure opens this and the high-pressure fuel is through the stroke of the pressure booster piston 64 from the high pressure room 78 pushed out and through the injector openings 56 through into the combustion chamber 38 injected.

The external dead center of the pressure booster piston 64 is also limited by a stop, not shown, so as to ensure that always about the same volume and about the same mass (density of the fuel is temperature-dependent) in the combustion chamber 38 is injected. The attacks can be made adjustable. As mentioned, the injection pressure is always the same, because the fuel injection valve opens at the specified high pressure and there this pressure via the pressure booster 62 with the pressure in the combustion chamber 38 correlated.

During the following suction stroke of the engine piston 6 becomes the larger piston area 66 by the pressure reduction in the combustion chamber 38 relieved of pressure and the pressure booster piston 64 by the spring and / or the low pressure in the high-pressure chamber 78 shifted back towards its inner dead center, with the volume of the high-pressure chamber 78 enlarged and over the opened low-pressure inlet valve 34 Fuel from the low pressure line 82 in the enlarging high pressure room 78 continues to flow. Upon reaching the internal dead center of the pressure booster piston 64 and the engine piston 6 the internal combustion engine is ready for the next cycle. In the illustrated embodiment, the back annulus 73 of the pressure intensifier 62 connected to the environment and thus depressurized. In principle, you could also change the injection timing by the in the annulus 73 effective pressure (preferably a gas pressure) is designed variable.

As explained, in the embodiment described above, injection valves 54 used, as they are commonly used in UP units application. Based on 3 and 4 an embodiment is explained in which the injection valve 54 practically in the injection unit according to the invention 48 is integrated. Similar to the embodiment described above, the injection unit 48 in the cylinder head 50 installed - of course, the injection unit can be recognized in all the described embodiments in a separate housing to the cylinder or the cylinder head.

At the in 3 illustrated embodiment, the cylinder head 50 with the blind bore designed as a guide hole 72 provided in the pressure booster piston 64 of the pressure intensifier 62 is guided axially displaceable. In the illustrated embodiment, the pressure booster piston 64 designed as a cup-shaped hollow piston, in the piston bore 86 one on the cylinder head 50 supported pump piston 88 dips. This is designed as a plunger, which is coaxial with the pressure booster piston 64 from a soil 90 the guide hole 72 protrudes and with its end portion in the piston bore 86 dips. Strictly speaking, the axially displaceable pressure booster piston forms 64 thus a cylinder for the stationary pump piston 88 ,

In the distance to the pump piston 88 is the piston bore 86 in the radial direction to a guide collar 92 downgraded and expanded following this (left in 3 ) to a nozzle body room 94 in which an injection nozzle body 96 the injection unit 54 is guided axially displaceable. In its illustrated closed position is the injector body 96 with a cone 98 at a nozzle seat 100 on that in a piston bottom 102 of the pressure booster piston 64 is trained. As shown in 3 is the piston crown 102 formed approximately conical and bulges in the combustion chamber 38 into it.

In a partial circle around the axis of the injection unit are in the piston head 102 a variety of injector openings 56 formed over the at from the nozzle seat 100 lifted cone 98 High pressurized fuel from the nozzle body space 94 in the combustion chamber 98 can be injected.

In the illustrated embodiment is on the inner peripheral surface of the piston crown 102 a likewise cone-shaped bag 104 formed, which extends radially inwardly to the annular nozzle seat 100 connects and through the a cone room 106 is formed, in which open the injector openings.

The injector body 94 has a ge over the cone 98 in the radial direction projecting collar 108 located along the peripheral wall of the nozzle body space 94 is guided and this in a back annulus 110 and a valve seat side seat space 112 divided.

The back extends from the waistband 108 a guide pin 114 who is the leader 92 interspersed and guided in this. In the transition area to the federal government 108 is the guide pin 114 slightly widened in the radial direction, leaving a stop step 116 is formed during the opening stroke of the injector body 96 on the adjacent end face of the federal government 108 accumulates and thus the opening stroke of the injector body 96 limited.

At the annular space-side end face of the guide collar 92 is a spring 118 supported on the adjacent end face of the collar 108 attacks and thus the cone 98 towards the nozzle seat 100 biases. As shown in 3 limit the piston bore 86 , the guide pin 114 and the pump piston 88 together the high pressure room 78 , whose diameter d that of the pump piston 88 equivalent. The diameter D of the guide bore 72 corresponds to the outside diameter of the pressure booster piston 64 - according to 3 is the combustion chamber 38 assigning end face of the pressure booster piston 64 with the diameter D with the gas pressure in the combustion chamber 38 so that the transmission ratio is calculated as a function of the diameter ratio D / d.

As shown in 3 is the high pressure room 78 about that towards this opening low pressure inlet valve 84 and a low pressure flow path connected to a fuel tank, not shown, so that at an enlargement of the high pressure space 78 Fuel from the tank into the high pressure room 78 can be promoted. This can be done for example by means of a pre-feed pump. In the illustrated embodiment, this low-pressure flow path is partially in the pressure booster piston 64 and the pump piston 88 integrated. In this case, the inlet connection of the designed as a check valve low pressure inlet valve 84 to a low pressure channel 120 of the pressure booster piston 64 its connected by the low pressure inlet valve 84 distant end portion in a longitudinal pocket 122 on the inner peripheral wall of the piston bore 86 empties. In the pump piston 88 is a pump piston channel 124 formed, on the one hand in the longitudinal pocket 122 on the other hand connected to a channel or a supply line which is connected to the tank or the pressure connection of the prefeed pump. The channels described above 120 . 124 For example, can be designed as angle holes or the like. The axial length of the longitudinal pocket 122 is chosen so that in each relative position between pump piston 124 and pressure booster piston 64 a low-pressure side pressure medium connection is ensured. In principle, however, it is sufficient if this longitudinal pocket 122 allows a low pressure connection to the fuel tank only in the Kraftstoffansaugphase.

Instead of the above, in the pressure booster piston 64 and the pump piston 88 integrated ducting could in principle also be an elastic hose to the pressure booster piston 64 are connected, which is then connected via a further, cylinder head side line to the tank. However, this flexible line is likely to be more difficult to implement than the channel described above.

In the from the ground 90 and the pilot hole 72 and a stepped back surface 126 of the pressure booster piston 64 limited space is a pressure booster spring 128 arranged on the one hand on the ground 90 is supported and on the other hand on an annular shoulder of the pressure booster piston 64 engages, so that this in its illustrated basic position with an annular end face 130 against a stop shoulder 132 is biased.

In the upstream of the low pressure inlet valve 84 trained low-pressure channel 120 opens a discharge channel 134 a, via a pressure relief valve 136 in pressure medium connection with the annulus 110 can be brought. When exceeding the pressure relief valve 136 set pressure in the annulus 110 opens the pressure relief valve 136 , so that a pressure medium connection to the low-pressure channel 120 and over the long side 122 and the pump piston channel 124 to the tank (or the pre-feed pump) is controlled - accordingly, the pressure in the annulus 110 do not exceed the set maximum pressure.

As in 3 further indicated is the annulus 110 and the high pressure room 78 via a nozzle bore 138 connected to each other, so that in the illustrated basic position in the high-pressure chamber 78 and in the annulus 110 in about the same pressure is applied.

The high pressure room 78 is further via an arcuate injection channel 140 with the seating area 112 connected, so that in the basic position in this, too, the pressure in the high-pressure chamber 78 is applied.

In the in 3 illustrated basic position of the pressure booster 62 is the pressure in the combustion chamber 38 relatively low, so that the pressure over booster piston 64 by the force of the pressure booster spring 128 against the stop shoulder 182 is biased. The injector body 96 is by the force of the spring 118 and the pressure in the high pressure room 78 , which corresponds approximately to the pre-feed pressure, in the direction of its closed position against the nozzle seat 100 biased. Accordingly, the prefeed pressure is also in the annulus 110 and in the sitting room 94 at.

Now rises due to a compression stroke of the engine piston 6 the pressure in the combustion chamber 38 on, so moves the pressure booster piston 64 against the force of the pressure booster spring 128 to the right, with the still on the nozzle seat 100 overlying injector body 96 is taken. During the axial displacement of the pressure booster piston 64 to the right ( 3 ), the pump piston dives 88 into the piston bore 86 a, so that corresponding to the volume of the high-pressure chamber 78 is reduced and the fuel is subjected to a correspondingly higher pressure, wherein the ratio between the pressure in the combustion chamber 38 and in the high pressure room 78 is given by the diameter ratio D / d. As stated previously, the pressure in the annulus increases 110 accordingly. Upon reaching the pressure relief valve 136 set maximum pressure opens this, allowing the pressure in the annulus 110 is held at this predetermined value. The nozzle bore 138 is designed so that in the relatively short time no pressure compensation via the nozzle bore 138 between the pressure room 78 and the annulus 110 can be done. As a result, in the closing direction of the injection nozzle body 96 reduced effective forces, so that the cone 98 from the nozzle seat 100 can take off. By during the compression stroke of the engine piston 6 further increasing pressure in the combustion chamber 38 becomes the pressure booster piston 64 moved further to the right, so that according to the illustration in 4 Fuel from the shrinking high-pressure chamber 78 displaced and over the injection channel 140 , the sitting room 112 through the cone 98 and the nozzle seat 100 limited annular gap, the cone space 106 and through the injector openings 56 through into the combustion chamber 38 is injected.

The area ratios are, for example, chosen so that at a compression pressure of 40 bar in the combustion chamber 38 an injection pressure of 1200 bar in the high-pressure chamber 78 established.

The opening stroke of the injector body is by running the stop step 116 on the leadership 92 limited. During injection, the pressure booster piston moves 64 first to the right (view according to 4 ). After a predetermined stroke of the guide pin runs 114 of the injector body 96 on the face of the pump piston 88 on, so that the injector body 116 is moved back in the closing direction until the cone 98 on the nozzle seat 100 rests. In this relative position of the injector body 96 is also the stroke of the pressure booster piston 64 limited to the right, so the pump piston 88 also as a stop for the pressure booster piston 64 acts.

By the on the nozzle seat 100 seated injector body 96 the injection process is terminated, wherein during the subsequent power stroke of the engine piston 6 the pressure in the annulus 110 and in the pressure intensifier room 78 is initially locked and thus the pressure booster piston 64 to the left (view in 4 ), so that the volume of the high-pressure chamber 78 is increased accordingly. Here is the pressure relief valve 136 closed.

After the pressure has dropped in the increasing pressure chamber 78 below the prefeed or tank pressure opens the low pressure inlet valve 84 , so that fuel into the high-pressure space 78 can flow. In this case, the pressure booster piston 64 by the force of the pressure booster spring 128 and the prefeed pressure in the high-pressure chamber 78 further accelerates to the left, until he with his ring end face 130 on the stop shoulder 132 runs up - the intensifier 62 is then ready for the next injection cycle.

With such a variant, wherein the injection valve 54 in the pressure intensifier 62 is integrated, the manufacturing costs of the injection system compared to the conventional solutions with common rail systems can be significantly reduced, so that in terms of efficiency and on investment costs meaningful use in free-piston engines is made possible.

The above-described concept with a pneumatic / hydraulic pressure booster 62 can also be used in the per se known pump-nozzle injection systems. Such injection systems are, for example, under www.kfztech.de described. Usually, in these pump-nozzle systems, a pump piston is driven directly via a camshaft of the internal combustion engine, so that fuel sucked from a fuel supply and pressurized with high pressure is conveyed into a high-pressure chamber. The fuel supply and discharge to and from the high-pressure chamber is controlled by a solenoid valve, wherein with the solenoid valve closed, the high-pressure fuel from the high-pressure chamber is injected via a spring-biased injection valve into the combustion chamber. According to the invention can now be used instead of vorbe pump piston described the pneumatic / hydraulic pressure booster 62 use to pressurize the fuel in the high-pressure chamber with high pressure. This would be the pressure booster 62 Initially, the fuel in circulation to the tank promote and only when driving the solenoid valve (ie when closing the circulation) generate the high pressure for injection. After the injection could then be switched back to circulation via the solenoid valve. With such an injection unit one would have full flexibility with regard to pre-injection, post-injection and injection quantity.

In the solutions described above could be the injection timing and the injection quantity by adjustable stops or by an adjustable pressure booster spring 128 vary.

In the embodiments according to the 1 to 4 one could further the injection timing and thus also the injection volume by a change in pressure in the effective in the closing direction annulus (pressure in the through the receiving bore 72 limited annulus according to 2 or in the annulus 110 according to the 3 or 4 ) change.

Disclosed is an injection unit for an internal combustion engine, For example, a combustion engine with crank mechanism or a Free-piston machine, with one guided in a cylinder Engine piston defining a combustion chamber and with an injection unit for injecting fuel into the combustion chamber, wherein a Inlet connection of the injection unit connected to a high-pressure line is. According to the invention is in the high pressure line arranged a pressure intensifier, which has a large Has effective surface and a small effective area, the larger effective area of the Pressure in the combustion chamber indirectly or directly applied is. The smaller effective area delimits a high-pressure space, to which the high pressure line is connected.

1

Free piston engine

2

motor housing

4

combustion cylinder

6

piston

8th

hydraulic pistons

10

axial bore

12

ring end face

14

working cylinder

16

face

18

compression cylinder

20

pressure channel

22

ND Channel

24

ND memory

26

check valve

28

HD channel

30

HD memory

32

starting valve

34

check valve

36

exhaust port

38

combustion chamber

40

inlet space

42

overflow

44

inlet channel

46

intake valve

48

Injection unit

50

cylinder head

52

cooling channel

54

Injector

56

injectors opening

58

High-pressure line

60

pressure connection

62

Pressure intensifier

64

Pressure booster piston

66

size piston area

68

small piston area

70

piston section

72

guide bore

73

annulus

74

Piston rod section

76

Intensifier housing

78

High-pressure chamber

80

Low pressure port

82

Low-pressure line

84

Low-pressure inlet valve

86

piston bore

88

pump piston

90

ground

92

guide collar

94

Nozzle body space

96

injector body

98

cone

100

nozzle seat

102

piston crown

104

bag

106

cone space

108

Federation

110

annulus

112

sitting room

114

spigot

116

stop step

118

feather

120

Low pressure passage

122

vertical pocket

124

Pump piston channel

126

back

128

Intensifier spring

130

ring end face

132

stop shoulder

134

relief channel

136

Pressure relief valve

138

nozzle bore

140

Injection channel

QUOTES INCLUDE IN THE DESCRIPTION

This list The documents listed by the applicant have been automated generated and is solely for better information recorded by the reader. The list is not part of the German Patent or utility model application. The DPMA takes over no liability for any errors or omissions.

Cited patent literature

• - DE 4044591 A1 [0003]
• DE 10120196 A1 [0003, 0040]

Cited non-patent literature

• - www.motorlexikon.de [0050]
• - www.kfztech.de [0079]

Claims (20)

Injection unit for injecting a fuel or fuel mixture into a combustion chamber of an internal combustion engine, wherein an inlet connection to a high-pressure line ( 58 ), characterized in that the high pressure line ( 58 ) a pressure booster ( 62 ) with a large effective area ( 66 ) and a small effective area ( 68 ), the larger effective area ( 66 ) of the gas pressure in the combustion chamber ( 38 ) is acted upon and the smaller effective area ( 68 ) a high pressure room ( 78 ) to which the high pressure line ( 58 ) connected. Injection unit according to claim 1, with a pressure chamber ( 78 ) opening low-pressure inlet valve ( 84 ), which is used to supply fuel to a low-pressure line ( 32 ) connected. Injection unit according to claim 1 or 2, wherein a pressure booster piston ( 64 ) is designed as a hollow piston, in the back of a housing-fixed pump piston ( 88 ) and in which an injection nozzle body ( 96 ), which together the high pressure space ( 78 ), from the fuel when lifting the injector body ( 96 ) from a nozzle seat ( 100 ) into the combustion chamber ( 38 ) is injectable. Injection unit according to claim 3, wherein the injection nozzle body ( 96 ) at a distance to a high-pressure chamber ( 78 ) sectionally limiting end face with a collar ( 108 ), through which a seat-side sitting space ( 112 ) from a high pressure side annulus ( 110 ) is separated, the latter via a pressure relief valve ( 136 ) with the low-pressure line ( 120 . 124 ) is connectable. Injection unit according to claim 4, wherein the high pressure space ( 78 ) and the annulus ( 110 ) via a nozzle ( 138 ) are interconnected. Injection unit according to claim 4 or 5, wherein the annular space ( 110 ) a spring space for a the injection nozzle body ( 96 ) in the closing direction biasing spring ( 118 ). Injection unit according to one of the claims 4 to 6, wherein the high-pressure space ( 78 ) with the seat space ( 112 ) via an injection channel ( 140 ) connected is. Injection unit according to one of claims 4 to 7, wherein in a piston head ( 102 ) of the injection nozzle body ( 96 ) Nozzle bores ( 56 ) are formed. Injection unit according to one of claims 5 to 8, wherein the injection nozzle body ( 96 ) after a stroke of the pressure booster piston ( 64 ) on the pump piston ( 88 ), so that the stroke of the pressure booster piston ( 64 ) is limited in pressure build-up direction and the injection nozzle body ( 96 ) is adjustable back to its closed position. Injection unit according to one of the claims 5-9, wherein in the low pressure flow path a flexible Line is provided, which is a pressure booster piston side Flow path with a cylinder head side flow path combines. Injection unit according to one of claims 5 to 9, wherein the low-pressure flow path ( 120 . 122 . 124 ) in sections along a sliding guide between the pump piston ( 88 ) and pressure booster piston ( 64 ) runs. Injection unit according to one of the preceding claims, wherein the injection unit ( 48 ) an injection valve ( 54 ), when reaching a certain, via the pressure booster piston ( 64 ) applied high pressure to the combustion chamber ( 38 ) opens. Injection unit according to one of the preceding claims, wherein the pressure booster piston ( 64 ) via a pressure booster spring ( 128 ) or the low pressure is biased towards a home position. Injection unit according to one of the preceding claims, wherein the stroke of the pressure booster piston ( 64 ) about attacks ( 130 . 132 ; 114 . 88 ) is limited. Injection unit according to claim 14, wherein at least one of the stops is adjustable. Injection unit according to one of the preceding claims, wherein a high pressure side effective surface of the pressure booster ( 62 ) defines a piston space of a pump-nozzle injection unit, which is connectable via a solenoid valve to a tank or for injection with an injection nozzle. Internal combustion engine with at least one in a cylinder ( 4 ) guided engine pistons ( 6 ), which has a combustion chamber ( 38 ) and with an injection unit according to one of the preceding claims. Internal combustion engine according to claim 17, wherein a pressure intensifier ( 62 ) of the injection unit at least in sections in a cylinder head ( 50 ) of the cylinder ( 4 ) is recorded. Internal combustion engine according to patent claim 18, wherein a pressure booster piston ( 62 ) of the pressure intensifier ( 62 ) at least in sections in a guide bore ( 72 ) of the cylinder head ( 50 ) is guided. Internal combustion engine according to claim 19, wherein a piston section ( 75 ) with the smaller effective area ( 68 ) in a to the cylinder head ( 50 ) attached pressure booster housing ( 76 ), to which the low-pressure line ( 82 ) connected.