Classifications

• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
  • F02M—SUPPLYING COMBUSTION ENGINES IN GENERAL WITH COMBUSTIBLE MIXTURES OR CONSTITUENTS THEREOF
  • F02M59/00—Pumps specially adapted for fuel-injection and not provided for in groups F02M39/00 -F02M57/00, e.g. rotary cylinder-block type of pumps
  • F02M59/02—Pumps specially adapted for fuel-injection and not provided for in groups F02M39/00 -F02M57/00, e.g. rotary cylinder-block type of pumps of reciprocating-piston or reciprocating-cylinder type
  • F02M59/10—Pumps specially adapted for fuel-injection and not provided for in groups F02M39/00 -F02M57/00, e.g. rotary cylinder-block type of pumps of reciprocating-piston or reciprocating-cylinder type characterised by the piston-drive
  • F02M59/105—Pumps specially adapted for fuel-injection and not provided for in groups F02M39/00 -F02M57/00, e.g. rotary cylinder-block type of pumps of reciprocating-piston or reciprocating-cylinder type characterised by the piston-drive hydraulic drive

Definitions

• the invention relates to a fuel injection system for internal combustion engines according to the preamble of claim 1 and a method for injecting fuel into the combustion chamber of an internal combustion engine according to claims 15 and 16.
• a pressure booster is connected between the injection pump and the injection nozzle.
• the full injection pressure is only present in the area around the injection nozzle.
• the fuel supply is bypassed directly from the high pressure area of the injection pump.
• the invention has for its object to provide a fuel injection system in which the thermal load on the injection pump is reduced and the possible pressure increase rates in the
• Fuel injection system to be improved.
• higher injection pressures should be made possible and at the same time the stress and the drive power requirement of the injection pump should be reduced.
• this object is achieved by a
• Fuel injection system for internal combustion engines with an injection nozzle and with an injection pump having a high-pressure part, the high-pressure part of the injection pump with the injection nozzle via a control line connected to the low-pressure side of a pressure intensifier and a high-pressure path connected to the high-pressure side of the pressure intensifier There is an operative connection, a delivery line being present, which delivers fuel to the injection nozzle and in which a first check valve is arranged, which
• Injection pressure is only present between the high pressure side of the pressure intensifier and the injection nozzle. At the same time, the pressure forces acting on the injection pump are reduced. This also reduces the leakage and throttling losses, which leads to a reduction in the drive power requirement and the hydraulic Improved fuel injection system efficiency.
• the fuel remains comparatively cold in the high-pressure area of the fuel injection system because it is fed directly from the low-pressure part of the injection pump. As a result, the compressibility of the fuel is lower, which results in an improved rate of pressure increase in the fuel injection system, and a larger mass flow can be promoted through the injection nozzle.
• the thermal and hydraulic improvement of the fuel injection system enables smaller injection hole diameters of the injection nozzle, which improves the mixture formation in all operating points.
• the pressure booster has a translation piston which can be moved in a bore, the end faces of which each delimit a pressure chamber, the first, larger end face of which delimits a first pressure chamber connected to the control line, and whose second, opposite and smaller end face a second, limited pressure space connected to the high pressure path, so that the pressure intensifier is easy to manufacture, has a good hydraulic efficiency and can be easily adapted to different operating conditions.
• the delivery line is connected to the second pressure chamber, so that the fuel in the part of the fuel nozzle that is furthest away from the injection nozzle
• High pressure area is introduced and is conveyed from there to the injection nozzle.
• This has the advantage that the fuel is continuously replaced by relatively cold fuel in the high-pressure region of the fuel injection system.
• a first check valve is arranged in the delivery line, which prevents the backflow of fuel from the injection nozzle into the delivery line, so that the injection pressure is not applied to the low-pressure supply of the injection pump.
• the first check valve is spring-loaded, so that the backflow of fuel from the injection nozzle into the delivery line is prevented with the greatest reliability under all operating conditions.
• Another variant provides that the change in cross-section of the transmission piston and a shoulder in a housing of the pressure booster limit a relief space, so that any leakage losses of the pressure booster can be collected and discharged.
• the relief chamber is connected to the part of the delivery line which lies between the low-pressure supply and the check valve, so that the leaks of the pressure booster are returned to the fuel injection system.
• a return spring is clamped in the relief space, which is supported on a stationary system and thereby the transmission piston on the relief space side
• a second check valve is arranged in the connecting line between the relief space and the delivery line, which blocks the connection in the direction from the delivery line to the relief space, so that the delivery line is not excited by the pressure vibrations in the relief space.
• a further variant of the invention provides that a spool valve configured as a check valve with a blocking direction from the control line to the delivery line is arranged between the control line and the delivery line, so that as soon as the pressure in the control line drops below the pressure in the delivery line the flush valve reaches a filling of the control line. This leads to a lowering of the temperature level also in this area and thereby improves the hydraulic behavior of the
• Pressure difference between the control line and the delivery line opens, so that the movement of the translation piston into its starting position is also supported in this embodiment by the pressure in the delivery line and the difficult filling of the, especially at high speeds
• Control line is guaranteed in the area between the injection pump and pressure intensifier, because at high speeds, the pressure in the feed pump is high.
• Another embodiment of the invention provides that the part of the larger end face of the translation piston on which the pressure of the control line acts when the transmission piston rests against its pump-side stop, larger than the smaller end face of the transmission piston, that in the delivery line between the first check valve and the injection pump there is a third
• Check valve is arranged with the same blocking direction, and that between the control line and the first and third check valve, a connecting line with a fourth check valve with the blocking direction from the delivery line to the control line is arranged, so that at the beginning of
• Injection bypassing the pressure booster fuel is pumped directly from the high-pressure part of the injection pump into the injection nozzle.
• the pressure increase rate changes at the beginning of the injection, as a result of which the combustion noise can be improved and the metering of small pre-injection quantities is also made easier by measures on the pump side.
• the third and the fourth check valve are combined to form a bypass valve, so that the number of components is reduced and costs are thereby avoided.
• a two-part translation piston is provided, so that the manufacture, assembly and hydraulic properties of the injection system are improved.
• control line is relieved of pressure between the injections
• Fuel is delivered from the low pressure supply via the delivery line to the injection nozzle
• the fuel injection is controlled by the high pressure part of the injection pump.
• Leakage and throttling losses improve the hydraulic efficiency of the system and thus further reduce the drive power required.
• the low temperature enables steeper pressure increases due to the lower elasticity of the fuel and a higher mass flow through the nozzle with the same delivery rate.
• the thermal and hydraulic improvements to the fuel injection system allow smaller injection hole diameters for the injection nozzles and thus better mixture formation at all operating points.
• FIG. 1 shows a schematic representation of a first embodiment of the fuel injection system according to the invention
• Fig. 2 a schematic representation of a second
• Embodiment of a fuel injection system according to the invention 3: shows a schematic representation of a third embodiment of a fuel injection system according to the invention
• FIG. 4 a schematic representation of a fourth Embodiment of the fuel injection system according to the invention
• FIG. 5 a schematic representation of a combination of different embodiments of a fuel injection system according to the invention.
• Fig. 1 shows a Kraf material injection system with an injection nozzle 1 and an injection pump 3, which has a high-pressure part 5 and a low-pressure supply 7.
• the low-pressure supply 7 can also be designed as a pump separate from the injection pump 3.
• low-pressure supply 7 and high-pressure part 5 are shown in FIG. 1
• Injection pump 3 always shown as a unit. However, an embodiment is always also conceivable in which the above-mentioned. There is a separation of the low-pressure supply 7 and the injection pump 3.
• the high-pressure part 5 is operatively connected to the injection nozzle 1 via a control line 9 and a high-pressure path 10.
• a pressure intensifier 11 is arranged between the control line 9 and the high pressure path 10.
• the pressure intensifier 11 has a first pressure chamber 13, a second pressure chamber 15, a one-part or multi-part translation piston 17, which is guided in a bore 18, and a relief chamber 19 in a housing 12.
• the translation piston 17 can be made in one part or two parts.
• Two-part translation pistons 17 consist of a first piston, which has the diameter of the first pressure chamber 13 of the pressure intensifier 11, and a further piston, which has the diameter of the second pressure chamber 15 of the pressure intensifier 11.
• the hydraulic force acting on the first piston is transmitted indirectly or directly to the second piston.
• Two-part translation pistons 17 can have advantages over one-part translation pistons 17 in terms of manufacture, assembly and hydraulic properties.
• the first pressure chamber 13 and the end face of the translation piston 17 projecting into the first pressure chamber 13 form the low-pressure side of the pressure intensifier 11.
• the second pressure chamber 15 and the end face of the translation piston 17 projecting into the second pressure chamber 15 form the high-pressure side of the pressure intensifier 11.
• Booster piston 17 the pressure in the second pressure chamber 15 is higher than that of the high-pressure part 5 of the injection pump 3, in accordance with the ratio of the two end faces of the booster piston 17.
• the relief space 19 is delimited by a change in cross-section 20 of the transmission piston 17 and a shoulder in a housing 12 of the pressure booster 11.
• the second pressure chamber 15 between the injections is filled with fuel from the low-pressure supply 7 of the injection pump 3 via a delivery line 21. If the second pressure chamber 15 and the high-pressure path 10 are filled with fuel, the injection process can take place in that the high-pressure part 5 of the injection pump 3 begins to deliver fuel. In the pressure intensifier 11, the pressure is increased and the fuel is injected into the combustion chamber through the injection nozzle 1 with this increased pressure.
• a first check valve 23 is arranged in the delivery line 21.
• the first check valve 23 can be spring-loaded, as shown in Fig. 1, or without a spring, such as. B. indicated in Fig. 2, executed.
• the high-pressure area of the fuel injection system according to the invention is therefore limited in FIG. 1 to the area to the right of the transmission piston 17 and above the first check valve 23. This fact was indicated by the dashed lines.
• the leakages occurring between the translation piston 17 and the housing of the pressure booster 11 collect in the relief chamber 19 and are transferred to the delivery line 21 with each injection process via a connecting line 25.
• the translation piston 17 moves back into its starting position. This is done in that the control line 9 is relieved of pressure, for example, via the high-pressure part 5 of the injection pump 3 and the pressure piston 17 in the second pressure chamber 15 and the relief chamber 19 is acted upon by the pressure of the low-pressure supply 7 of the injection pump 3 via the delivery line 21 , Since the pressure in the delivery line 21 is higher than the pressure in the pressure-relieved control line 9, the moves
• the pressure relief does not have to lead to a reduction in the pressure to ambient pressure, but provision can be made to maintain a static pressure which is above the ambient pressure even during the pressure relief. It can also in the relief space 19 a return spring can also be provided.
• the same reference numerals were used as in FIG. 1 in the fuel injection system.
• the embodiment according to FIG. 2 has a return spring 27 in the relief chamber 19, which acts on the transmission piston 17 against the injection movement.
• the return spring is clamped between a cross-sectional change 20 of the translation piston 17 and a paragraph of the bore 18 or the housing 12.
• the return spring 27 can, for example, coaxially surround the transmission piston 17.
• a second check valve 29 is arranged in the connecting line 25, which prevents fuel from the delivery line 21 from reaching the relief chamber 19. After the end of the injection, the translation piston 17 becomes its pump side
• the delivery line 21 is not subjected to the pressure fluctuations resulting from the oscillating movement of the transmission piston 17.
• the return spring 27 can be designed with a low preload and spring rate and thus to save space.
• 3 shows a further embodiment of the fuel injection system according to the invention.
• a flushing valve 31 is arranged between the control line 9 and the delivery line 21 in this embodiment.
• the flushing valve 31 is spring-loaded so that it opens when the pressure difference determined by the spring of the flushing valve 31, for example 15 bar, between the delivery line 21 and the control line 9. When this pressure difference is reached, fuel is delivered from the delivery line 21 into the control line 9.
• the thus improved filling and flushing of the control line 9 has the advantage over the embodiments according to FIGS. 1 and 2 that in this area the
• the temperature level is lowered by supplying relatively cold fuel and thus the hydraulic behavior is improved.
• the risk of "seizures" in the high pressure part 5 of the injection pump 3 is reduced, since this part of the
• Injection system can be flushed better. Furthermore, the difficult filling of the control line 9 at high engine speeds is ensured.
• the pressure intensifier 11 has a compression stage component 33 in its first pressure chamber 13. This compression component 33 has the task of ensuring that only when a certain differential pressure between the
• Control line 9 and the second pressure chamber 15 of the translation piston 17 leaves the pump-side stop.
• This function can be achieved, for example, in that the compression component 33 has a part of the end face of the protruding into the first pressure chamber 13
• Translation piston 17 covers when the translation piston 17 is in its initial position, the remaining area of the transmission piston 17 being larger than the end face of the transmission piston 17 projecting into the second pressure chamber 15.
• Return spring 27 determines the pressure difference up to which the high-pressure side of the transmission piston 17 acted upon by the pressure of the delivery line 21 and the return spring 27 hold the translation piston 17 in its initial position against the pressure of the control line 9.
• a third and a fourth check valve 35 and 37 are shown.
• the third check valve 35 is arranged in the delivery line 21 between the first check valve 23 and the injection pump 3 and has the same blocking direction as the first check valve 23.
• the fourth check valve 37 is arranged in a connecting line 39 between the control line 9 and the delivery line 21. The blocking direction of the fourth check valve 37 is selected so that the
• the connecting line 25 branches off from the delivery line 21 between the low-pressure supply 7 and the third check valve 35.
• Pressure surface 13 projecting end face of the translation piston 17 is acted upon by the pressure of the control line 9.
• the pressure intensifier becomes effective because the first check valve 23 prevents the further inflow of fuel via the delivery line 21 into the second pressure chamber 15.
• Bypassing the pressure intensifier 11 at the beginning of the injection cycle changes the pressure increase rate of the fuel in the second pressure chamber 15 and thus also the injection nozzle 1. This makes the metering of small pre-injection quantities easier by measures on the pump side and the combustion noise can be improved.
• FIG. 5 represents the combination of the embodiments shown in FIGS. 2, 3 and 4. This is intended to clarify that these embodiments can be freely combined with one another. This also applies to the embodiment shown in FIG. 1.

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• 1999
  • 1999-09-24 DE DE19945785A patent/DE19945785B4/de not_active Expired - Fee Related
• 2000
  • 2000-09-19 US US09/856,637 patent/US6446603B1/en not_active Expired - Fee Related
  • 2000-09-19 EP EP00978946A patent/EP1133636A1/de not_active Withdrawn
  • 2000-09-19 BR BR0007169-2A patent/BR0007169A/pt active Search and Examination
  • 2000-09-19 JP JP2001527111A patent/JP2003510516A/ja active Pending
  • 2000-09-19 WO PCT/DE2000/003243 patent/WO2001023753A1/de not_active Application Discontinuation
  • 2000-09-19 CN CNB008020477A patent/CN1144942C/zh not_active Expired - Fee Related

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