EP0629265B1 - Fuel injecting device working according to the solid energy accumulator principle, for internal combustion engines - Google Patents

Abstract

The fuel injection system has a unit for producing increase in pressure which includes an impingement device (25), e.g. a rear wall or a piston type stop. The impingement device is provided in a fuel storage element (6) arranged outside an injection pump (1), connected at a pressure line (2) between the injection pump and the injection nozzle (3). The storage element (6) includes a fuel storage chamber (22), in which a spring preloaded diaphragm (23) is arranged. One side of the chamber is arranged at a specified distance to the diaphragm.

Description

The invention relates to a device for injecting fuel for internal combustion engines of the type specified in the preamble of claim 1.

Injection devices, whose electrically operated reciprocating pumps operate according to the so-called solid-state energy storage principle, have a delivery piston or cylinder which is accelerated in a certain way almost without resistance, fuel being generally moved before the delivery pressure which builds up to Spraying the fuel through the injector is required. In this way, kinetic energy is absorbed or stored before the actual pressure build-up required for injection, which is then suddenly converted into a pressure increase in the fuel.

In a so-called pump-nozzle element known from DD-PS 120 514, which works according to the solid-state energy storage principle, the fuel delivery chamber accommodating the delivery piston of the injection pump has, in a first section, axially parallel grooves in the inner wall through which Fuel can flow to the rear of the delivery piston if the delivery piston starts to move without any noticeable pressure build-up in the fuel.

The adjoining second section of the fuel delivery chamber is the actual pressure chamber, which has no grooves. If the accelerated delivery piston enters this pressure chamber, it is suddenly braked by the incompressible fuel, whereby the stored kinetic energy is converted into a pressure surge, through which the resistance of the injection valve is overcome, so that fuel is sprayed off. The disadvantage here is that when the delivery plunger is immersed in the second section of the delivery space, because of unfavorable gap conditions, namely a relatively large gap width and a relatively small gap length, noticeably high pressure losses occur, which in particular reduce the possible speed and pressure level of the pressure build-up and thus make the spraying process unfavorable influence. The pressure losses are caused by fuel flowing out of the pressure chamber into the pressure antechamber (first section of the fuel delivery chamber).

According to DD-PS 213 472, this disadvantage is to be avoided by mounting an impact body in the pressure chamber of the delivery cylinder on which the piston accelerates almost without resistance, so that the pressure loss during pressure build-up due to a relatively large gap length despite a relatively large gap width (large manufacturing tolerances ) between the impact body and the pressure chamber inner wall area can be kept reasonably small. The disadvantage here, however, is that the impacting process leads to a high level of wear on the bodies that meet. In addition, the impact body is set into longitudinal vibrations by the impact, which are transferred to the fuel and disrupt the injection process there as high-frequency pressure vibrations.

A particular disadvantage of these known solid-state energy storage injection devices is that the injection process can be controlled only to a very limited extent, that is to say it can only be adapted to the load conditions of the engine to a very limited extent. The same applies to the fuel injection device according to DE-OS 23 07 435, in which the reciprocating piston pump has a sleeve-shaped pump cylinder as a movable pump member, which is arranged in a longitudinally displaceable manner on a pump piston fixed in the pump housing and limits the pump pressure space, which is connected to the injection valve device via a longitudinal bore in the pump piston. A cross hole in the pump cylinder allows fuel to flow to the back of the cylinder when storing energy. Passing over the front edge of the piston with the bore leads to pressure build-up and thus to fuel spraying. In this case, too, high gap losses occur when the pressure builds up.

The object of the invention is to provide a cost-effective, easy-to-manufacture device for injecting fuel of the type mentioned at the outset, with which wear-free fuel can be injected without any noticeable pressure losses when building up pressure, and fuel can be precisely controlled depending on the load, and which is particularly suitable for high-speed internal combustion engines.

This object is achieved by the characterizing features of claim 1. Advantageous further developments of the invention are characterized in the subclaims.

• Fig. 1 bis 8 schematisch im Längsschnitt verschiedene Ausführungsformen der erfindungsgemäßen Einspritzvorrichtung,
• Fig. 9, 10 und 11 schematisch eine der erfindungsgemäßen Einspritzvorrichtung zuarbeitende Kraftstoffzuführeinrichtung für einen Motorstart und einen Motor-Notlauf ohne Batterie,
• Fig. 12 schematisch eine bevorzugte Schaltung zur Ansteuerung der Spule der erfindungsgemäßen Einspritzvorrichtung,
• Fig. 13, 14 und 15 bevorzugte Ausführungsformen des Einspritzventils der erfindungsgemäßen Einspritzvorrichtung im Längsschnitt, und
• Fig. 16 eine Kraftstoffversorgungseinrichtung ohne Rückleitung zum Tank.

The invention is explained in more detail by way of example with reference to the drawing. Show it:

• 1 to 8 schematically in longitudinal section different embodiments of the injection device according to the invention,
• 9, 10 and 11 schematically a fuel supply device for the injection device according to the invention for an engine start and an engine emergency operation without a battery,
• 12 schematically shows a preferred circuit for controlling the coil of the injection device according to the invention,
• 13, 14 and 15 preferred embodiments of the injection valve of the injection device according to the invention in longitudinal section, and
• 16 shows a fuel supply device without return line to the tank.

In the invention, an initial partial stroke of the delivery element of the injection pump is provided, in which the displacement of the fuel does not result in a pressure build-up, the delivery element partial stroke serving for energy storage expediently being provided by a storage volume e.g. is determined in the form of an empty volume and a stop element which, as will be explained in more detail below with reference to the exemplary embodiments, can be designed differently, for example in the form of a spring-loaded membrane or a spring-loaded piston element, against which fuel is conveyed and which is displaced on a stroke path "X" allow the fuel element to displace fuel; only when the spring-loaded element is pressed against a e.g. abuts a firm stop, an abrupt pressure build-up is generated in the fuel, so that a displacement of the fuel in the direction of the injection nozzle is effected.

The injection device according to FIG. 1 has an electromagnetically driven reciprocating piston pump 1, which is connected to an injection nozzle device 3 via a delivery line 2. A suction line 4 branches off from the delivery line 2 and is connected to a fuel reservoir 5 (tank). In addition, a volume storage element 6 is connected via a line 7 to the delivery line 2, for example in the area of the connection of the suction line 4.

The pump 1 is designed as a piston pump and has a housing 8 in which a magnet coil 9 is mounted, an armature 10 which is arranged in the region of the coil passage and is designed as a cylindrical body, for example as a solid body, and is guided in a housing bore 11 which is located in the region the central longitudinal axis the ring coil 9 is located, and is pressed by means of a compression spring 12 into an initial position in which it rests on the bottom 11a of the housing bore 11. The compression spring 12 is supported on the end face of the armature 10 on the injection nozzle side and an annular step 13 of the housing bore 11 opposite this end face. The spring 12 includes, with play, a delivery piston 14, which is fixed, for example in one piece, to the armature 10 on the armature end face acted upon by the spring 12 , connected is. The delivery piston 14 plunges relatively deep into a cylindrical fuel delivery chamber 15 which is formed coaxially in the axial extension of the housing bore 11 in the pump housing 8 and is in transmission connection with the pressure line 2. Due to the immersion depth, pressure losses during the sudden pressure increase can be avoided, and the manufacturing tolerances between piston 14 and cylinder 15 can even be relatively large, for example need only be in the hundredths of a millimeter range, so that the manufacturing outlay is low.

A check valve 16 is arranged in the intake line 4. A ball 18, for example, is arranged in the housing 17 of the valve 16 as a valve element, which in its rest position is pressed by a spring 19 against its valve seat 20 at the end of the valve housing 17 on the reservoir side. For this purpose, the spring 19 is supported on the one hand on the ball 18 and on the other hand on the wall of the housing 17 opposite the valve seat 20 in the region of the mouth 21 of the intake line 4.

The storage element 6 has, for example, a two-part housing 22, in the cavity of which a membrane 23 is tensioned as the organ to be displaced, which separates a space filled with fuel from the pressure line and which, in the relaxed state, divides the cavity into two halves, which are sealed against each other by the membrane. On the side of the membrane 23 facing away from the line 7, a spring force acting on it acts in an empty space, the storage volume, for example a spring 24, which acts as a return spring for the membrane 23 is set up. The spring 24 is supported with its end opposite the membrane on an inner wall of the cylindrically widened empty cavity. The empty cavity of the housing 22 is delimited by an arched wall, which forms a stop surface 22a for the membrane 23.

The coil 9 of the pump 1 is connected to a control device 26 which serves as an electronic control for the injection device.

In the de-energized state of the coil 9, the armature 10 of the pump 1 is located on the bottom 11a due to the prestressing of the spring 12. The fuel supply valve 16 is closed and the storage membrane 23 is held in the housing cavity by the spring 24 in its position away from the stop surface 22a.

When the coil 9 is actuated via the control device 26, the armature 10 with the piston 14 is moved in the direction of the injection valve 3 against the force of the spring 12. The feed piston 14 connected to the armature 10 displaces fuel from the feed cylinder 15 into the space of the storage element 6. The spring forces of the springs 12, 24 are relatively soft, so that fuel displaced by the feed piston 14 during the first partial stroke of the feed piston 14 presses the storage membrane 23 into the empty space almost without resistance. As a result, the armature 10 can initially be accelerated almost without resistance until the storage volume or empty space volume of the storage element 6 is exhausted by the membrane 23 striking the arch wall 22a. The displacement of the fuel is suddenly stopped and the fuel is suddenly compressed due to the already high kinetic energy of the delivery piston 14. The kinetic energy of the armature 10 with the delivery piston 14 acts on the liquid. This creates a pressure surge that travels through the pressure line 2 to the nozzle 3 and there leads to the spraying of fuel.

For the end of the delivery, the coil 9 is switched off. The armature 10 is moved back to the bottom 11a by the spring 12. The amount of liquid stored in the storage device 6 is sucked back via the lines 7 and 2 into the delivery cylinder 15 and the membrane 23 is pushed back into its starting position due to the action of the spring 24. At the same time, the fuel supply valve 16 opens, so that fuel is sucked out of the tank 5.

A valve 16a is expediently arranged in the pressure line 2 between the injection valve 3 and the branches 4, 7 and maintains a stand pressure in the space on the injection valve side, which pressure e.g. is higher than the vapor pressure of the liquid at the maximum temperature, so that bubbles are prevented. The parking pressure valve can e.g. be designed as the valve 16.

A storage piston 31 can also be used as a displacement element for the storage element 6 instead of the membrane 23. The stop, which suddenly stops storing in this case, can be designed to be adjustable according to the invention, so that the path length of the acceleration stroke of armature 10 and delivery piston 14 can be changed. A cable pull, for example coupled to the throttle valve of the engine, is preferably used for this adjustment. Alternatively, the adjustment can expediently be controlled by the control device 26, for example by means of an actuating magnet. Figure 2 shows e.g. an embodiment of the storage element 6 with a displacement piston 31 adjustable by a cable 40.

The storage element 6 according to FIG. 2 has a cylindrical housing 30 which can be formed integrally with the pressure line 2. As the organ to be displaced, a storage piston 31 is used, which is guided with a close fit on the inner wall of the cylinder housing 30, so that no significant leakage can occur, with an empty volume 33c being provided in the cylinder 30, into which the piston 31 can be displaced. Existing leakage fluid can escape from the empty volume space 33c through a drain hole 32 and is supplied to the fuel tank 5 (see FIG. 1). The drain hole 32 is formed in the cylinder wall of the housing 30 in the region of the housing cover 33, which lies opposite the housing wall 33a, which is integrally formed with a wall section of the pressure line 2. The drain hole 32 extends approximately radially to the central longitudinal axis 33b of the cylindrical housing 30.

A compression spring 34 is clamped between the inside of the housing cover 33 and the end face of the piston 31 opposite this wall, which presses the piston 31 into its rest position against the opposite end wall 33a of the housing, in which a bore 35 is formed which is in the central longitudinal axis 33b of the housing 30 lies and opens into the pressure line 2.

The housing cover 33 of the housing 30 is extended in a tubular manner in the axial direction, and in the passage of the extension tube 36 a stop bolt 37 is slidably guided like a piston and has a ring 38 at the end located in the space 33c. The piston 31 abuts against the underside of the ring 38 when it is moved from its rest position towards the housing cover 33. This stop element 37 is preloaded by means of a spring 39. For this purpose, the spring 39 is supported on the one hand on the inside of the cover 33 and on the other hand on the ring step of the ring 38 of the bolt 37. A cable 40 is fastened to the part of the bolt 37 arranged outside the cylinder 30 and is connected, for example, to the throttle valve of the engine. The stop pin 37 can be adjusted in the direction of the central longitudinal axis 33b of the housing 30 by means of the cable 40, so that the possible stroke of the piston 31 can also be varied in accordance with the position of the stop ring 38. The stop bolt 37 can be adjusted depending on the required acceleration stroke of the armature 10 of the pump 1 (FIG. 1).

The operation of the storage element 6 according to FIG. 2 corresponds essentially to that of the storage element 6 according to FIG. 1. During a first partial stroke of the delivery piston 14 and the armature 10 (FIG. 1), the storage piston 31 of the storage element 6 is displaced from it by displaced fuel Fig. 2 shown rest position, the return spring 34 is relatively soft, so that the fuel moved by the armature 10 on the delivery piston 14 can be displaced with almost no resistance of the storage piston 31. As a result, the armature 10 with the delivery piston 14 is almost resistance-free on part of the stroke, i.e. essentially accelerated only against the spring force of the springs 12, 34 until the storage piston 31 abuts with its spring-loaded end face against the stop ring 38, as a result of which the fuel located in the delivery cylinder 15 and in the pressure line 2 abruptly due to the high kinetic energy of the armature 10 and delivery piston 14 compresses and this kinetic energy is transferred to the liquid. The resulting pressure surge then leads to fuel being sprayed out via the nozzle 3.

The adjustable stop pin 37 is also suitable for the exclusive control of the amount of fuel to be injected for certain engines.

3 shows a valve 90 which is designed as an integral storage element feed valve. The integral storage element feed valve 90 has a housing 91 which is constructed in a unitary manner with the housing 8 of the pump 1 and the pressure line 2. A central longitudinal bore 92 is made in the housing 91, which ends at one end via an opening 93a in the pressure line 2 and at the other end opens into a cylindrical valve chamber 93, with channels 94 also leading from the bore 92 to the valve chamber 93. The valve element is constructed in two parts and comprises a cylinder 95 guided in the valve chamber 93, in the cylindrical, continuous central step bore of which a piston 96 is displaceably guided. In the outer lateral surface of the cylinder 95, axially parallel grooves 97 are formed. The cylinder 95 is pressed into its rest position by a spring 98, in which it rests with its one end face on the tank-side bottom of the valve chamber 93, into which a fuel supply line 99 coming from the fuel tank opens. In the bore for receiving the piston 96 sits a spring 100 on the tank side, which presses the piston 96 against the pressure line side bottom of the valve chamber 93, so that the bore 92 is covered, a space 95a being formed for the piston 96 in the tank-side interior of the cylinder 95 becomes.

The valve 90 works as follows. When the delivery piston 14 performs a suction stroke, fuel is drawn from the line 99 in that the cylinder 95 is lifted off from the tank-side bottom surface of the valve chamber 93 by the negative pressure against the pressure of the spring 98, so that fuel via the longitudinal grooves 97, the valve chamber 93 and the channels 94 and the bore 92 can flow into the pressure line 2. In this process lies the piston 96, as shown in FIG. 3, on the pressure line-side bottom of the valve chamber 93. At the end of the suction stroke, the cylinder 95 is pressed by the spring 98 into the position shown in FIG. 3, in which the cylinder 95 again lies sealingly against the tank-side bottom of the valve chamber 93.

At the beginning of the delivery stroke of the delivery piston 14, the piston 96 guided in the cylinder 95 is moved out of its abutment on the pressure line side bottom of the valve space 93 due to the relatively soft design of the spring force of the spring 100 and pressed into the free space 95a, the resulting additional space in the Valve chamber 93 flows fuel from the pressure chamber 15, 2, which is displaced during the conveying movement of the delivery piston 14, fuel on the end of the piston 96 on the tank side being pushed back by the piston 96 into the tank via the line 99. The delivery stroke of the delivery piston 14 is ended in that the piston 96 strikes the end of the piston 95 with its end face acted upon by the spring 100 against the step in the central longitudinal bore of the piston 95. As a result of this abrupt termination of the essentially resistance-free acceleration stroke of the armature 10 with the delivery piston 14, the formation of a very steep pressure rise in the pressure line 2 is brought about, as a result of which fuel is sprayed off via the nozzle 3 at high pressure.

According to a further variant of the invention, provision is made for the storage element 6 to be constructed in a unitary manner with the delivery piston of the reciprocating piston pump 1. A corresponding exemplary embodiment is shown in FIG. 4. A storage piston 80 serves as the storage element, which is pressed in a first central longitudinal axis step bore section 14b on the pressure line side of a step bore 14a centrally through the piston 14 and the armature 10 against a stop (not shown) on the pressure line side by a spring 81. The piston 80 projects in the rest position with its one end face into the pressure chamber 15. The bore section 14b in the delivery piston 14 receiving the storage piston 80 sits after the step 14c towards the armature 10 in a further stepped bore section 14d, on the step 14e of which the compression spring 81 is supported, which presses against the armature-side end face of the piston 80. After step 14e, the bore 14a finally also passes through the armature 10 and opens into the empty armature space 11, so that air can be displaced.

The memory element of this embodiment works as follows. On a first part of the stroke of the delivery piston 14, the energy storage path, the storage piston 80 is pushed into the bore of the delivery piston 14 provided for the piston, whereby an additional space for displaced fuel is available on the pressure chamber side, so that the armature 10 during the first stroke section can be accelerated essentially without resistance together with the delivery piston 14. The resistance-free acceleration of armature 10 and delivery piston 14 is ended when the armature-side end face of the storage piston 80 comes to bear against the annular shoulder 14c of the stepped bore 14a. The consequence of this is an abrupt pressure increase, by means of which fuel is sprayed off via the nozzle 3.

FIG. 5 shows an exemplary embodiment of the injection pump, which essentially has the structure of the injection pump 1 according to FIG. 1. For the hydraulic damping, a cylindrical projection 10a is formed centrally on the back of the armature 10 in the manner of a piston-cylinder arrangement, which in the last section of the armature return movement suitably enters a pocket cylinder bore 11b in the base 11a, which on the stop surface 11a for the armature 10 in the housing 8 is trained. Longitudinal grooves 10b are formed in the armature 10, which connect the armature-back space 11 to the armature-front space 11. In the space 11 there is a medium, for example air or fuel, which can flow through the grooves 10b when the armature 10 moves. The depth of the blind cylinder bore 11b corresponds approximately to the length of the projection 10a (dimension Y in FIG. 8). Because the projection 10a can dip into the blind cylinder bore 11b, the armature return movement is greatly delayed in the last section, as a result of which the desired hydraulic damping of the armature return movement is brought about by displacement of the medium from the space 11b.

6a shows a variant of the hydraulic damping. In this exemplary embodiment, too, the pump chamber 11 through which the delivery piston 14 passes is connected in front of the armature 10 to the space 11 adjoining the armature rear side, namely through bores 10d which open into a central overflow channel 10c in the region of the armature rear side. A central pin 8a of a shock absorber 8b protrudes with its conical tip 8c in the direction of the mouth of the overflow channel 10c, reaches through a hole 8d in the bottom 11a at the rear, which opens into a damping space 8e, and ends in the damping space with a ring 8f which has a larger diameter than the hole 8d. A spring 8g supported on the bottom of the damping space presses against the ring 8f and thus the pin 8a into its rest position (FIG. 6a). A channel 8h connects the damping space 8e to the rear armature space 11. The channels 10c and 10d allow the armature 10 to move almost without resistance during the acceleration phase.

The damping device 8b is ineffective in the acceleration movement of the armature 10, so that there is no impairment of the lifting phase. During the return movement, the mouth of the overflow channel meets the cone tip 8c and is closed, so that the flow through the channels 10c and 10d is interrupted. The armature 10 presses the pin 8a against the spring force and against the medium in the room 8e, which is also in the room 11 and flows out through the channel 8h into the room 11. The flows and spring forces are selected so that optimal damping is guaranteed.

Instead of the channel 8h, a displacement hole 8i can be arranged centrally in the pin 8a according to FIG. 6b, through which the damping medium can be pressed into the overflow channel 10c.

According to a further advantageous embodiment of the injection device according to the invention, it is provided that the energy stored in the return spring 12 of the armature 10 is used to advantage in the return movement of the armature 10. According to the invention, this can take place, for example, in that the anchor when resetting, a pumping device is used, which can be used for the fuel supply to the injection device to stabilize the system and to prevent bubbles or as a separate oil pump for engine lubrication. 7 shows a corresponding exemplary embodiment of an oil pump 260 connected to the fuel injection pump 1.

The fuel injection device shown in FIG. 7 is otherwise designed in accordance with FIG. 4, that is to say has a fuel inflow and outflow control element for controlling the first partial stroke of the delivery piston 14. The oil pump 260 is connected to the rear bottom 11a of the pump housing 8. Specifically, the oil pump 260 comprises a housing 261 which is connected to the housing 8 of the injection pump and in the pump chamber 261b of which a pump piston 262 is arranged, the piston rod 262a of which projects into the working chamber 11 of the armature 10, the piston 262 being acted upon by a return spring 263, which is supported on the housing base 261a in the region of an outlet 264.

In addition, the pump chamber 261b of the housing is connected to an oil reservoir 266 via an oil supply line 265. A check valve 267 is used in the oil supply line 265, the structure of which is similar to the valve 16 in FIG. 1.

The oil pump 260 works as follows. If the armature 10 of the injection pump 1 is moved in the direction of the injection nozzle 3 during its working stroke, the volume of the pump chamber 11 in the housing 8 behind the armature 10 is increased, as a result of which the oil pump piston 262 is moved in the direction of the armature 10 and finally by the action of the return spring 263 is transferred to its rest position. Oil is sucked from the reservoir 266 into the working space 261b of the oil pump 260 via the valve 267. During the return movement of the armature 10 of the pump 1 in the direction of its stop 11a, the oil pump piston 262 is pushed into the oil pump chamber 261b at least over part of the return path of the armature 10. It is by the Pump pressure closes the valve 267 and oil is discharged via the outlet 264 in the direction of arrow 264a from the oil pump and pressed to the locations of the engine to be supplied with oil.

The oil pump 260 can alternatively also be used as a fuel back pressure pump, wherein the fuel can be supplied to the valve device 70. It is advantageous here that the pump 260 can generate a static pressure in the fuel supply system which prevents vapor bubbles from forming e.g. counteracts heating of the entire system.

In addition, the inventive design of the additional pump 260 on the pump 1 causes rapid damping of the armature 10, so that the armature 10 does not rebound against the stop 11a.

Figures 8a and 8b show a particularly effective and simple damping device. The structure of the pump device 1 is the same as that shown in FIG. 9. The blind cylinder bore 11b according to FIG. 12a is larger in diameter than the diameter of the cylindrical projection 10a. The projection 10a is surrounded by a sealing lip ring 10e projecting in the direction of the blind cylinder bore 11b and made of an elastic material which fits into the blind cylinder bore 11b. An insertion bevel at the mouth of the blind cylinder bore 11b facilitates the entry of the lips of the sealing lip ring 10e into the blind cylinder bore 11b. This damping device provides good damping when the armature 10 strikes and does not hinder the acceleration stroke of the armature. The elastic damping element 10e with sealing lips projecting axially parallel plunges positively into the pocket cylinder bore 11b during the return stroke of the armature 10 and rests against the inside wall of the pocket cylinder bore 11b in a sealing manner to the outside.

The blind cylinder bore 11b according to FIG. 8b is also larger in diameter than the cylindrical projection 10a. A sealing ring 10f made of elastic material sits positively on the wall of the blind cylinder bore 11b and points in the area of the Mouth inward-facing sealing lips 10g. The cylindrical projection 10a is plunged into the elastic sealing element 10f, the sealing lips 10g being pressed against the cylindrical projection 10a due to the outflowing damping medium, so that particularly good damping of the armature 10 is achieved.

With the aid of the injection device according to the invention, an engine start without a battery and an engine emergency run without a battery can be operated. This possibility is described in more detail below with reference to FIGS. 9, 10, 11.

The electrically driven or electronically controlled injection requires sufficient electrical energy to start and run. In the event that the electrical energy is not available in sufficient size, the possibility according to the invention should be created to start engines with the injection according to the invention even without electrical energy, for example by means of a hand crank drive. The required fuel is provided by an auxiliary device, as explained in more detail below. If the engine reaches a speed at which the generator provides sufficient energy, the fuel auxiliary device is switched off according to the invention and the injection is controlled electrically or electronically, corresponding to the normal case.

There are engines that are started without electrical energy, e.g. by hand or kick start device. These include small motors from hand tools, two-wheelers or outboards. This starting device is required because there is no battery to start and / or run. In addition, engines should be able to start without electrical energy, for example even when the battery is discharged.

According to the invention, the possibility of starting engines without electrical energy by means of an auxiliary device is achieved in that the fuel supply condition present on each engine, for example the inlet gradient or the pressure of the fuel feed pump at starting speed, is used. The fuel is fed directly to the intake manifold or the overflow in two-stroke engines or a metering device. Then the engine reaches a speed at which the generator has sufficient energy for the Provides injection, a valve blocks the direct fuel supply to the engine, the fuel is fed to the injector and this then takes over the fuel supply to the engine.

9 shows an arrangement according to the invention for supplying fuel to an engine 500. In this case, after a fuel back pressure pump 501, which is connected on the suction side to a fuel reservoir 502, the fuel supply to the engine is branched. In the de-energized state, an injection device 504, which is connected to a generator 503 and is constructed in accordance with one of the above exemplary embodiments, is inactive, and an, for example, electromagnetically actuated control valve 505 is opened for the fuel supply to an atomizer 506 on the engine 500.

When the engine 500 is started, the fuel pressure supplied by the pre-pressure pump 501 is supplied to the atomizer 506 located on the engine 500 via the opened control valve 505. The flow resistance of the control valve 505 and / or the atomizer 506 is dimensioned such that the supply of pressure from the admission pressure pump 501 at the starting speed covers the fuel required for the start. When the generator 503 coupled to the engine reaches a speed at which the energy required for the injection device 504 is covered, an injection control 507 becomes active, which is also fed by the generator 503 and is connected to the injection device 504 via a control line. For this purpose, the control valve 505 is closed by means of a current signal, so that no more fuel can be fed directly to the engine. At the same time, the injection device 504, controlled by the injection control 507, takes over the injection via the injection nozzle 508.

A hand pump 509 present on many engines can optionally also be used during the starting process for the direct fuel supply to the engine via the atomizer 506. The Hand pump 509 is arranged in the connecting line 511 from the pump 501 to the control valve 505. The control valve 505 is activated by the injection control 507 via a control line 510.

FIG. 10 shows a modification of the arrangement according to FIG. 9, in which the control valve 505 is arranged in the injection line 511 between the injection device 504 and the injection nozzle 508. The function of stormless starting corresponds to the function explained above with reference to FIG. 9.

In order to ensure the flow of fuel without pump support of the injection device 504, the flow resistance of the injection device 504 is kept small. It is advantageous here that the injection device 504 and the injection line 511 can be vented without problems. If the injection device 504 is to be vented, the control valve 505 is de-energized via an off switch 512 in the line from the injection control 507 to the control valve 505, unless this has already been done by the injection control 507. As a result, the control valve 505 is opened in the direction of the atomizer 506, and the air in the system can escape with simultaneous pumping, for example with the form pressure pump 501 or the hand pump 509.

The engine emergency running without battery provided according to the invention will be described in more detail below with reference to FIG. 11.

The arrangement shown in FIGS. 9 and 10 can also be used for the emergency operation of the engine, in which, for example due to failure of the generator, there is insufficient energy available for the injection control and the injection device. According to the invention, a quantity variation of the fuel takes place by a metering device, for example by an adjustable throttle in the control valve coupled to the throttle valve in the air intake pipe, which allows the engine load to be controlled in a makeshift manner.

11 shows a suitable embodiment of the control valve or the metering valve 505 in FIGS. 9 and 10. The control valve 505 has a housing 520, into which a coil 521 is inserted, which serves to drive an armature 522, which is shown in FIG a bore 523 of the housing 520 is slidably mounted and in its rest position is pushed by a return spring 524 against an adjustable stop 525 arranged in the housing 520, to which a cable pull 526 is connected outside the housing. Longitudinal grooves 527 are formed in the armature 522, which allow fuel in the bore 523 to communicate between the front and rear of the armature 522. The piston-shaped stop 525 extends through the housing end wall 520b and is biased in the housing 520 by means of a spring 528 with respect to the housing end wall 520b.

A metering piston 527 is formed uniformly with the end face of the armature 522 opposite the stop 525. This end face is also acted upon by the return spring 524, which is supported at the other end against the end wall 520a of the housing 520. The metering piston 527 protrudes with a conically tapering tip end into the delivery line 511, from which a connecting line 511a branches off to the atomizer 506.

The cable pull 526, which is connected to the stop 525 biased under spring force against the armature 522, is connected to the throttle valve 530 (see FIGS. 10, 11). The throttle valve position is thereby transferred directly to the stop 525.

The function of the control valve 505 is as follows. In the de-energized state of the coil 521, the armature 522 and the metering piston 527 rest against the stop 525 by the return spring 524. The fuel can flow from the feed pump 501 through the feed line 511 to the atomizer 506. If the control valve 505 is excited by the control device, the armature 522 presses the metering piston 527 against the force of the spring 524 to the extent Delivery direction until the inlet cross section 531 of the delivery line 511 is closed.

If the engine is operated in emergency mode without injection, the control valve 505 is de-energized and thus the inlet cross section 531 in the line 511 to the atomizer 506 is released. Corresponding to the throttle valve position, the conical metering piston 527 is pressed more or less far into the bore of the inlet cross section 531 via the armature 522 through the stop 525. The coupling to the throttle valve 530 is chosen so that the cross-section 531 is opened more with increasing opening of the throttle valve 530. In the idle position of throttle valve 530, a minimal gap remains at cross section 531, which allows the amount of idle fuel to pass to atomizer 506.

12 shows a preferred circuit for controlling the armature excitation coil of the injection pumps according to the invention, which ensures optimum acceleration of the armature.

It is known to dose the amount of fuel to be sprayed, for example in a time-controlled manner. A purely time-based control has proven to be disadvantageous, however, because the time window that results between the minimum and maximum amount of fuel to be sprayed is too small to differentiate the quantity spectrum required in engine operation in a differentiated and reproducible manner. However, a sufficiently differentiable quantity metering can be achieved via the pure intensity control of the current flow according to the invention.

In the case of the electromagnetic drive of the fuel injection devices according to the invention, in particular the excitation, ie the product of the number of turns of the coil and the current strength of the current that passes through the coil, is decisive for the electromagnetic-mechanical energy conversion. This means that an exclusive control of the current amplitude allows the switching behavior of the drive magnet to be independent of the effects of coil heating and a fluctuating supply voltage to be clearly defined. In this way, such a control system takes into account in particular the electrical voltage conditions and the different temperature conditions, which usually fluctuate strongly in motors.

FIG. 12 shows a two-point control circuit according to the invention for the current amplitude of the current controlling a pump drive coil 600. The drive coil 600 is connected to a power transistor 601 which is connected to ground via a measuring resistor 602. A comparator 603 with its output is applied to the control input of transistor 601, for example to the transistor base. The non-inverting input of the comparator is acted upon by a current setpoint, which is obtained, for example, by means of a microcomputer, and the inverting input of the comparator 603 is connected to the side of the measuring resistor which is connected to the transistor 601.

In order to control the energy flow in the drive coil 600 independently of the supply voltage, the current consumed by the coil 600 is measured by the measuring resistor 602. If this current reaches the limit value specified by a microprocessor as the current setpoint, the comparator switches off the current for the coil 600 via the power transistor 601. As soon as the actual current value drops below the current setpoint, the transistor switches the coil current back on via the comparator. The current rise delay caused by the inductance of the coil 600 prevents the maximum permissible current from being exceeded too quickly.

The next switching cycle can then begin, and this clocking of the coil current of the coil 600 takes place as long as the reference voltage supplying the current setpoint is present at the non-inverting input of the comparator 603.

The circuit represents a clocked current source, the clocking only after reaching the one provided by the microprocessor Current setpoint. The energy and thus the quantity control of the pump device 1 can take place with this circuit in combination of the duration and / or the amount of the reference voltage provided by the microprocessor.

13, 14 and 15 show particularly advantageous embodiments of the injection nozzle (e.g. nozzle 3) for the injection device according to the invention.

This injection nozzle comprises a valve seat tube 701, at the free lower end of which the membrane 70 is arranged, optionally a jet-shaping pin insert 702 (which is seated in a central hole in the membrane 704), a nozzle holder 703, a membrane plate 704 biased towards the valve seat, and a snap ring 705 , a pressure line 706 which opens on the valve seat side into an annular channel 708 which is open towards the membrane 704 and is covered by the membrane, a pressure screw 707, a seal 709 for the nozzle holder 703 and a receptacle 710 for the nozzle holder 703.

With the membrane flat seat nozzle shown in FIGS. 13, 14 and 15 with nozzle pin 702 (FIG. 14) and without nozzle pin 702 (FIG. 15), good fuel atomization is achieved on the surface of an arched cone jacket. The shape and dimensions of this jacket include dependent on the dimensions and design of the outlet opening in the membrane (FIG. 14) and can optionally be adapted to the requirements of engine operation with the aid of a known pin or throttle pin with the known functional advantages.

The valve works almost without moving masses and is characterized by a specially designed metal membrane that works with a fixed flat valve seat. The membrane - at the same time because of the preload of the valve spring - can be preloaded against the direction of opening (eg by arching) by means of suitable, defined and permanent deformation. This allows fuel atomization at low pressures the nozzle opening formed by the central hole in the membrane 704, for example at low speeds and small injections (in low part-load operation). Machining the nozzle hole (rounding the edges, etc.) is easily possible from both directions.

In order to enhance the good closing effect on the valve of the injection nozzle opening outwards, the seat ring width of the flat seat (Fig. 14) can be matched to the preload of the membrane plate. The correct choice of the dimensions of the lower groove in the valve seat contributes to this, which results in the force acting on the membrane at a given standing pressure of the fuel in front of the valve seat. On the other hand, the membrane is effectively cooled by the fuel stored in the puncture or flowing through it.

The nozzle requires no lubrication and is therefore particularly suitable for petrol, alcohol and mixtures thereof. Due to the way it works - there is no volume downstream of the valve seat - comparatively lower hydrocarbon emissions from the engine are to be expected in this nozzle than with inwardly opening nozzles.

The nozzle consists of a few parts, so it is very easy and inexpensive to manufacture, mass-produce, maintain, check and replace parts.

Fuel supply systems for fuel injection systems are flushed with fuel to cool them and to remove vapor bubbles during operation. This means that the fuel delivery pump provides a larger amount of fuel than is required by the engine. This additional quantity is returned to the tank via a line and is used for heat dissipation and for the removal of fuel vapor bubbles. Vapor bubbles occur during engine operation due to the effects of heat and can disrupt or even prevent the function of the injection system. A restart of the still warm engine can also be caused by steam bubbles difficult or even prevented.

In certain engine applications, e.g. as an outboard motor on boats, a return line to the tank is not permitted by law for safety reasons.

According to a further embodiment of the invention, a fuel supply device with a fuel injection device according to the invention is therefore designed without a return line to the tank, wherein heat and steam bubbles can nevertheless be removed.

The invention solves this problem by using a second fuel pump, a gas separation chamber with a floating valve and a cooler. This arrangement can be attached directly to the engine and thus avoids pressurized fuel lines outside the engine compartment or the engine capsule. This is enough to meet the legal safety regulations.

16, this fuel supply device is explained in more detail below by way of example.

A pump 801 sucks the fuel 802 from the tank 803 and feeds it through a fuel line 804 to a gas separation chamber 805. The gas separation chamber 805 has a float 806 which operates a ventilation valve 807 which acts on a gas discharge line 808 arranged in the ceiling area above the liquid level 805a.

A fuel line 809 is branched off from the bottom of the gas separation chamber 805 and is connected to a pump 810 and leads to an injection valve 811 according to the invention, which is connected via a fuel line 812 to the gas separation container 805, which opens into the gas separation container 805 above the liquid level 805a. As a result, a pressure regulator 813 and a cooler 814 are seated in the fuel line 812 starting from the injection valve 811.

The new fuel supply device for a fuel injection device according to the invention works as follows: The pump 801 sucks the fuel 802 out of the tank 803 and feeds it to the gas separation chamber 805 until the vent valve 807 is closed by the float 806. The pump 810 takes the fuel from the bottom of the gas separation chamber 805 and builds up the pressure required for the respective injection system upstream of the pressure regulator 813. In terms of its delivery characteristic, the pump 810 is designed such that it applies the amount of fuel required for cooling and flushing the injection valve 811 and supplies it to the gas separation chamber 805 via the cooler 814. If only steam bubbles 805b are discharged into the gas separation chamber 805, the fuel level 805a will decrease, the float 806 opens the vent valve 807 until the pump 801 has delivered to the original level 805a. The vent valve 807 is connected to the air intake pipe 808 of the engine, so that the fuel vapors drawn from the air intake pipe cannot get unburned into the environment.

Claims (41)

1. Fuel injection device which operates in accordance with the principle of the solid-state energy store, in which a reciprocating piston element guided in a pump cylinder of a reciprocating pump driven by means of an electromagnet displaces in the pump region, before the injection, during an acceleration phase virtually without resistance, during which the reciprocating piston element stores kinetic energy, partial quantities of the fuel to be injected, and the displacement is suddenly stopped by a means interrupting the displacement so that a pressure impulse is generated in the fuel situated in a closed-off pressure chamber by the stored kinetic energy of the reciprocating piston element being transmitted directly to the fuel situated in the pressure chamber, and in which the pressure impulse is used for the injection of fuel through an injection nozzle device, characterised in that the means interrupting the displacement and generating the pressure impulse is a volume storage element (6) which is provided for the displacement of fuel during the acceleration phase and which is arranged outside the leading, fluid-tight contact region between reciprocating piston element and reciprocating piston cylinder of the reciprocating pump.
2. Device according to Claim 1, characterised in that the means for interrupting the displacement and for generating the pressure increase are constructed as a device (6, 50, 70, 90, 125, 218/223) having a stop means.
3. Device according to Claim 1 and/or 2, characterised in that the stop means (e.g. 37) is constructed to be adjustable in position.
4. Device according to one or more of Claims 1 to 3, characterised in that it has an electromagnetically driven reciprocating pump (1) which is connected to an injection nozzle device (3) via a delivery line (2), a suction line (4), in communication with a fuel reservoir (5), branching off from the delivery line (2) and the volume storage element (6) being corrected to the delivery line (2) via a line (7)
5. Device according to Claim 4, characterised in that the pump (1) has a housing (8) in which a toroidal coil (9) is mounted, a rotor (10) being arranged in the region of the coil passage and being constructed as a cylindrical body and guided in a housing cylinder, which rotor is situated in the region of the central longitudinal axis of the toroidal coil (9) and is pressed by means of a compression spring (12) into a starting position in which it bears against the floor (11a) of the housing cylinder, a delivery piston (14) being attached to the end face of the rotor (10) on the injection-nozzle side and plunging relatively deeply into a cylindrical fuel delivery space (15) which is arranged coaxially with the housing cylinder and is in transmitting communication with the pressure line (2).
6. Device according to Claim 4 and/or 5, characterised in that a non-return valve (16) is arranged in the suction line (4).
7. Device according to one or more of Claims 1 to 6, characterised in that the storage element (6) has a housing (22), in the hollow space of which a diaphragm (23) is fitted as the member to be displaced, which diaphragm separates off from the hollow space a fuel-filled space on the pressure-line side and in the relaxed state divides the hollow space into two halves scaled off from each other by the diaphragm, an empty space which has a vault-shaped wall (22a) as the stop means for the diaphragm (23) being arranged on that side of the diaphragm facing away from the line (7).
8. Device according to Claim 7, characterised in that a spring (24) which acts on the diaphragm (23) and functions as a return spring for the diaphragm (23) is arranged in the empty space on that side of the diaphragm (23) facing away from the line (7).
9. Device according to one or more of Claims 6 to 8, characterised in that a non-return valve (16a) which forms, in the space on the injection-valve side, a retaining space for maintaining a particular static pressure in the fuel is arranged in the pressure line (2) between the injection valve (3) and the pressure chamber, upstream of the branches (4, 7).
10. Device according to one or more of Claims 1 to 6 and 9, characterised in that a storage piston (31) guided in a cylindrical housing (30) in communication with the line (7) is used as the displacement member for the storage element (6), the cylinder (30) making available an empty volume (33c) into which the piston (31) coil be displaced by the fuel.
11. Device according to Claim 10, characterised in that a discharge bore (32) is provided in the region of the empty-space volume (33c).
12. Device according to Claim 10 and/or 11, characterised in that a compression spring (34) which presses the piston (31) into its rest position against a housing wall (33a) on the pressure-line side is fitted in the empty-space volume (33c).
13. Device according to one or more of Claims 10 to 12, characterised in that an axially adjustable stop pin (37) for the piston (31), which passes through the housing wall and is in communication with an adjusting means outside the housing, is arranged in the empty-space volume (33c).
14. Device according to one or more of Claims 1 to 6 and 9, characterised in that the fuel inlet valve (16) is also constructed as a storage element valve (50).
15. Device according to Claim 14, characterised by an integral storage element/inlet valve device (90), having a housing (91) in which there is formed a central longitudinal bore (92) which, at one end, opens into the pressure line (2) via an opening (93a) and, at the other end, opens into a cylindrical valve space (93), channels (94) additionally leading from the bore (92) to the valve space (93) and the valve element being constructed in two parts and comprising a cylinder (95) which is guided in the valve space (93) and in the cylindrical central stepped through-bore of which a piston (96) is displaceably guided, and there being formed in the outer circumferential surface of the cylinder (95) grooves (97) running axially parallel and the cylinder (95) being pressed by a spring (98) into its rest position, in which it rests with its one end face on the tank-side floor of the valve space (93), into which there opens a fuel supply line (99) coming from the fuel reservoir, and there being seated on the tank side in the bore, for the purpose of receiving the piston (96), a spring (100) which presses the piston (96) against the floor of the valve space (93) on the pressure-line side so that the bore (92) is covered, a free space (95a) for the piston (96) being formed in the tank-side interior space of the cylinder (95).
16. Device according to one or more of Claims 1 to 6 and 9, characterised in that the storage element (6) is of unitary construction with the delivery piston (14) of the reciprocating pump (1).
17. Device according to Claim 16, characterised in that as the storage element use is made of a storage piston (80) which, in a first central longitudinal-axial stepped bore portion (14b), on the pressure-line side, of a stepped bore (14a) passing centrally through the piston (14) and the rotor (10), is pressed by a spring (81) against a stop on the pressure-line side, the piston (80) projecting, in the rest position, with its one end face into the pressure chamber (13) and the bore portion (14b), which receives the storage piston (80), in the delivery piston (14) continuing, after a step (14c), towards the rotor (10) in a further stepped bore portion (14d), on the step (14e) of which there is supported a compression spring (81) which presses against the rotor-side end face of the piston (80).
18. Device according to one or more of Claims 1 to 17, characterised by a hydraulic damping device for the rotor element (10) of the reciprocating pump.
19. Device according to Claim 18, characterised in that the hydraulic damping device is constructed in the manner of a piston-and-cylinder arrangement, there being formed centrally on the rotor (10) a cylindrical projection (10a) which, in the last portion of the rotor return movement, fits into a blind cylinder bore (11b) in the floor (11a) of the cylinder, grooves (10b) being provided, running in the longitudinal direction, in the rotor (10) which connect the space at the rear side of the rotor to the space at the front side of the rotor in the pump cylinder.
20. Device according to Claim 18, characterised in that the pump space (11), through which passes the delivery piston (14), is connected upstream of the piston (10) to the space (11) adjoining the rear side of the rotor by bores (10d) which open, in the region of the rear side of the rotor, into a central overflow channel (10c), a central pin (8a) of a shock damper (8b) projecting with a conical point (8c) in the direction of the mouth of the overflow channel (10c).
21. Device according to Claim 20, characterised in that the central pin (8a) passes, at the rear, through a hole (8d) in the floor (11a), which hole opens into damping space (8e), the pin (8a) ending in the damping space with a ring (8f) which has a greater diameter than the hole (8d), and there being supported on the floor of the damping space a spring (8g) which presses against the ring (8f), and a channel (8h) connecting the damping space (8e) to the rear rotor space (11).
22. Device according to Claim 20, characterised in that there is provided centrally in the pin (8a) a displacement through-bore (8i), through which the damping medium can be forced into the overflow channel (10c).
23. Device according to Claim 18, characterised in that, during the return movement, the rotor (10) operates a pumping device which at the same time provides a damping device for the rotor (10).
24. Device according to Claim 23, characterised in that an oil pump (260) is connected to the rear floor (11a) of the pump housing (8), which oil pump has a housing (261) in the pump space (261b) of which there is arranged a pump piston (262), the piston rod (262a) of which projects into the working space (11) of the rotor (10), the piston (262) being acted on by a return spring (263) supported on the housing floor (261a) in the region of an outlet (264).
25. Device according to Claim 24, characterised in that the pump space (261b) is in communication with an oil reservoir (266) via an oil supply line (265), a non-return valve (267) being inserted into the oil supply line (265).
26. Device according to Claim 18 and/or 19, characterised in that the blind cylinder bore (11b) is greater in diameter than the diameter of the cylindrical projection (10a) and the projection (10a) or the blind cylinder bore (11b) have a sealing-lip ring (10e) or (10d), respectively, the scaling-lip rings forming the piston seal for the projection (10a).
27. Device according to one or more of Claims 1 to 26, characterised by an auxiliary starting device, having a control valve which is connected to an atomiser (506) of the engine (500) and is impinged by fuel from the fuel tank (502), and the flow resistance of which, together with that of the atomiser (506), is so dimensioned that at the starting speed the fuel demand required for starting can be met by the pressure supply of a pre-pressure pump (501), even without the addition of electrical energy to the injection device (504).
28. Device according to Claim 27, characterised in that there is provision, downstream of the fuel pre-pressure pump (501), which is connected on the suction side to the fuel reservoir (502), for a branching of the fuel supply to the engine, in the currentless state an injection device (504) which is connected to a generator (503) and is constructed in accordance with the invention, in particular with one of the exemplary embodiments according to the invention, being inactive and the control valve (505), which is for example electromagnetically actuated, being open for the fuel supply to the atomiser (506) on the engine (500).
29. Device according to Claim 27 and/or 28, characterised in that a hand primer (509), present on the engine, is additionally used during the starting process for direct fuel supply to the engine by means of the atomiser (506), which hand primer is arranged in the connecting line (511) from the pump (501) to the control valve (505), the control valve (505) being driven by the injection control device (507) via a control line (510).
30. Device according to Claim 27, characterised in that the control valve (505) is arranged in the injection line (511) between the injection device (504) and the injection nozzle (508).
31. Device according to Claim 30, characterised by a circuit breaker in the line line from the injection control device (507) to the control valve (505).
32. Device according to Claim 30 and/or 31, characterised in that the auxiliary starting device according to the invention is used for the emergency operation of the engine, a metering valve (505) bringing about a variation of the quantity of fuel.
33. Device according to Claim 32, characterised in that the metering valve (505) has a housing (520), into which there is inserted a coil (521) serving to drive a rotor (522) which is displaceably mounted in a bore (523) of the housing (520) and is urged in its rest position by a return spring (524) against an adjustable stop (525) which is arranged in the housing (520) and to which a cable pull (526) is attached outside the housing, longitudinal grooves (527) which allow a communication of the fuel present in the bore (523) between the front side and the rear side of the rotor (522) being formed peripherally in the rotor (522), and the stop (525), constructed in the form of a piston, passing through the housing end wall (520b) and being prestressed in the housing (520) with respect to the housing end wall (520b) by means of a spring (528), and a metering piston (527) being of unitary construction with that end face of the rotor (522) lying opposite the stop (525), and this end face additionally being acted on by the retum spring (524) which is supported, at the other end, against the end wall (520a) of the housing (520), and the metering piston (527) projecting with a conically tapering pointed end into the delivery line (511), from which furthermore a connecting line (511a) branches off to the atomiser (506), and the cable pull (526), which is attached to the stop (525) prestressed under spring force against the rotor (522), being connected to the throttle valve (530).
34. Device according to one or more of Claims 1 to 33, characterised by a circuit for driving the rotor-exciting coil (9, 600), which is connected to a power transistor (601) connected to earth via a precision resistor (602), a comparator (603) being connected by its output to the control input of the transistor (601), for example to the transistor base, and the non-inverting input of the comparator (603) receiving a current desired value obtained, for example, by means of a microcomputer and the inverting input of the comparator (603) being connected to that side of the precision resistor which is connected to the transistor (601).
35. Device according to one or more of Claims 1 to 34, having an injection nozzle characterised by a valve-seat tube (701) with an annular channel (708) at the end, a diaphragm plate (704) which is prestressed in the direction of the valve seat, has a central hole and covers the annular channel (708), if desired a spigot insert (702) in the hole of the diaphragm (704), a circlip (705) and a pressure line (706).
36. Device according to one or more of Claims 1 to 35, characterised by a fuel supply device without a return line to the tank, use being made of a second fuel pump, gas-separating chamber with float valve, and a cooler.
37. Device according to Claim 35, characterised by a gas-separating chamber (805), into which fuel (802) is pumped from a tank (803) by means of a pump (801) via a line (804), and from which fuel is supplied to an injection valve (811) by means of a pump (810) via a fuel line (809), a line (812) in which a pressure regulator (813) and a cooler (814) are arranged being led back into the gas-separating chamber (805) from the injection valve (811), there being provided in the gas separator (805) a float (806) which operates a vent valve (807) seated in a discharge line (808) which opens into the gas-separating chamber (805).
38. Device according to Claim 37, characterised in that the fuel line (812) opens into the gas-separating chamber (805) above the liquid level (805a).
39. Device according to Claim 36 and/or 38, characterised in that the vent line (808) opens into the gas-separating chamber (805) above the liquid level (805a).
40. Device according to one or more of Claims 37 to 39, characterised in that the fuel line (804) opens into the gas-separating chamber (805) above the liquid level (805a).
41. Device according to one or more of Claims 37 to 40, characterised in that all the devices of the fuel injection system are arranged in the engine compartment (815), except for the tank (803).

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