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
  • F02M59/44—Details, components parts, or accessories not provided for in, or of interest apart from, the apparatus of groups F02M59/02 - F02M59/42; Pumps having transducers, e.g. to measure displacement of pump rack or piston
  • F02M59/46—Valves
  • F02M59/466—Electrically operated valves, e.g. using electromagnetic or piezoelectric operating means
  • F02M59/468—Electrically operated valves, e.g. using electromagnetic or piezoelectric operating means using piezoelectric operating means
• • 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
  • F02M45/00—Fuel-injection apparatus characterised by having a cyclic delivery of specific time/pressure or time/quantity relationship
  • F02M45/12—Fuel-injection apparatus characterised by having a cyclic delivery of specific time/pressure or time/quantity relationship providing a continuous cyclic delivery with variable pressure
• • 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
  • F02M57/00—Fuel-injectors combined or associated with other devices
  • F02M57/02—Injectors structurally combined with fuel-injection pumps
• • 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
  • F02M59/20—Varying fuel delivery in quantity or timing
  • F02M59/36—Varying fuel delivery in quantity or timing by variably-timed valves controlling fuel passages to pumping elements or overflow passages
  • F02M59/366—Valves being actuated electrically
• • 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
  • F02M2200/00—Details of fuel-injection apparatus, not otherwise provided for
  • F02M2200/70—Linkage between actuator and actuated element, e.g. between piezoelectric actuator and needle valve or pump plunger
  • F02M2200/703—Linkage between actuator and actuated element, e.g. between piezoelectric actuator and needle valve or pump plunger hydraulic
  • F02M2200/704—Linkage between actuator and actuated element, e.g. between piezoelectric actuator and needle valve or pump plunger hydraulic with actuator and actuated element moving in different directions, e.g. in opposite directions

Definitions

• the invention is based on a fuel injection device for an internal combustion engine.
• a fuel injection device in the form of a pump-nozzle unit is known from the published patent application DE 35 23 536 AI.
• a pump-nozzle unit is provided for each combustion chamber of the internal combustion engine, in which a pump unit, a control valve and an injection valve are integrated in one unit.
• the pump unit consists of a pump piston that is driven synchronously with the internal combustion engine and immersed in a pump work space, where it displaces the fuel therein under high pressure.
• the pump work space is connected to the fuel injection valve, which opens at a certain fuel pressure and thus injects fuel under high pressure into the combustion chamber of the internal combustion engine.
• the control valve arranged in the housing of the pump-injector unit opens and closes a connection between the pump work chamber and a fuel supply system in which the fuel pressure is low and which both supplies fuel to the pump-injector unit and absorbs excess fuel. If the control valve is open, the fuel is led from the pump work space into the fuel supply system, so that no fuel pressure can build up in the injection valve and thus there is no injection. If the control valve closes, a corresponding pressure can build up and fuel is injected into the combustion chamber of the internal combustion engine. In this way, the start of the injection and the duration of the injected fuel quantity can be controlled.
• valve member is acted upon by a spring in the opening direction and held in the closed position by a controllable counterforce, which is applied here by an electromagnet. If the electromagnet is switched off, the spring pushes the valve member in the opening direction and the connection from the high pressure to the low pressure area is opened.
• the valve member of the control valve has in one embodiment shown in DE 35 23 536 AI a valve seat and a downstream in the flow direction from the high pressure area to the low pressure area a throttle collar on the valve member, through which the flow cross section in a certain range largely independent of the stroke of the valve member is.
• the known valve member has the disadvantage that when the valve member opens, a hydraulic force acts on the valve sealing surface, which is added to the opening force of the spring in the course of the opening stroke movement of the valve member. As a result, it is difficult to control the counter force of the electromagnet according to the requirements so that the valve member is held in a position in which the flow of fuel is throttled.
• the valve member has a relatively large stroke range in which the flow cross-section is independent of the stroke.
• the throttle gap is formed between a cylindrical section of the bore and the valve member and, viewed in the direction of flow of the fuel from the high-pressure chamber to the low-pressure chamber, lies upstream of the valve seat. The fuel flow from the high-pressure chamber is first passed through this throttle gap and then past the valve sealing surface to the low-pressure chamber, so that there is already a low fuel pressure at the valve sealing surface.
• valve member can also move to a third, throttling position in an easily controllable manner, so that a pre-injection with lower pressure is possible through the injection valve.
• FIG. 1 shows a longitudinal section through a fuel injection device
• Figure 2 is an enlargement of Figure 1 in the area of a control valve
• Figure 3 is a schematic representation of the flow cross-section controlled by the control valve as a function of the stroke of the valve member. Description of the embodiment
• FIG. 1 shows a longitudinal section through a fuel injection device according to the invention in the form of a pump-nozzle unit, as is used for injecting fuel into the combustion chamber of an internal combustion engine, in particular a self-igniting internal combustion engine.
• the pump-nozzle unit contains all components necessary for an injection, that is a high-pressure generating pump unit 39, an injection valve 1 and a control valve 11 which controls the start and the end of the injection.
• FIG. 2 shows an enlargement of FIG. 1 in the area of the control valve 11.
• the structure of the individual components is first explained and then their function as part of the pump-nozzle unit is explained.
• the injection valve 1 comprises an injection valve body 2, which is essentially designed as a cylinder with a stepped diameter and projects with one end into the combustion chamber of an internal combustion engine, not shown in the drawing.
• a blind bore 9 is formed, the closed end of which faces the combustion chamber and at which end at least one injection opening 7 is formed which connects the blind bore 9 to the combustion chamber of the internal combustion engine.
• a valve needle 3 is arranged in the blind bore 9, which is longitudinally displaceable against the force of a closing spring 5 and which opens and closes the at least one injection opening 7 through its opening stroke movement.
• the valve needle 3 is surrounded by a pressure chamber 8 formed in the injection valve body 2, which continues as an annular channel surrounding the valve needle 3 up to the injection openings 7 and can be filled with fuel under high pressure via a high pressure channel 10 formed in the injection valve body 2.
• a cylinder-shaped valve body 12 is arranged facing away from the combustion chamber and has an end face on the injection valve body 2 and the other end facing away from the combustion chamber comes into contact with a pump body 40, the injection valve body 2, valve body 12 and pump body 40 being connected by a valve Drawing, not shown, are braced against each other in the axial direction.
• the high-pressure channel 10 formed in the injection valve body 2 continues in the axial direction through the entire valve body 12 into the pump body 40.
• a bore 26 is formed in the valve body 12 as part of the control valve 11 in the axial direction, which is divided into a larger-diameter sealing section 126 and a smaller-diameter guide section 226, which is closed toward the combustion chamber, one at the transition between the two sections 126, 226 is designed as a valve seat 22 serving as an annular shoulder.
• a valve member 14 is arranged in the bore 26, which is sealingly guided in the sealing section 126 of the bore 26 and which tapers towards the combustion chamber to form a valve sealing surface 24 and projects into the guide section 226 of the bore 26. Towards the end of the valve member 14 on the combustion chamber side, it increases in diameter again and merges into a section 214 which is guided in the guide section 226 of the bore 26.
• a spring 27 is arranged under prestress, which acts on the valve member 14 away from the combustion chamber.
• the sealingly guided section 114 of the valve member 14 is surrounded by a high-pressure space 16 formed in the valve body 12, which is connected to the high-pressure channel 10 via a connecting bore 20.
• the control valve 11 opens and closes the connection to a low-pressure chamber 18, which is formed by the tapering of the valve member 14 and the guide branch formed between the sections 114 and 214 of the valve member 14. section 226 of the bore 26 is formed.
• the low pressure chamber 18 is connected to a fuel supply system 58 via an inlet channel 29.
• the fuel supply system 58 comprises a tank 66, from which fuel is conveyed into the low-pressure chamber 18 via a low-pressure line 60 by means of a feed pump 62.
• a pressure relief valve 64 is arranged parallel to the feed pump 62 and ensures that fuel can flow back into the tank 66 from the low pressure space 18 when a certain threshold pressure is exceeded.
• the end face 28 of the valve member 14 facing away from the combustion chamber extends into a control chamber 30 which is formed in a pump body 40 and is filled with fuel. Via the fuel pressure in the control chamber 30, a hydraulic force can be applied to the end face 28 of the valve member 14, which is directed counter to the force of the spring 27, so that the valve member 14 in the bore 26 moves in the longitudinal direction controlled by the fuel pressure in the control chamber 30 leaves .
• the control chamber 30 is connected via a connecting bore 33 to a spring chamber 38, which spring chamber 38 is delimited by the closed end of a guide bore 37 and the end face of a control piston 32, which is sealingly longitudinally displaceable in the guide bore 37.
• the control piston 32 is acted upon by a return spring 36 arranged under prestress in the spring chamber 38 and is connected on its end face facing away from the spring chamber 38 to a piezo actuator 34, which changes its extension by means of a suitable energization and thus the control piston 32 in the guide bore 37 can move.
• the control piston 32 displaces fuel from the spring chamber 38 during its longitudinal movement and presses the fuel through the connecting bore 33 into the control chamber 30, so that there the pressure and thus also the hydraulic force on the end face 28 of the valve member 14 changes accordingly.
• a throttle section 21 is formed in the bore 26, which has a somewhat larger diameter than the sealing section 126 of the bore 26.
• a narrow throttle gap 23 designed as an annular gap is formed between the throttle section 21 of the bore 26 and the outer surface of the valve member 14.
• the pump piston 42 is in its upper reversal point, so that the pump working space 48 has its maximum volume.
• the pump piston 42 is moved into the pump work chamber 48 by a mechanism, not shown in the drawing, so that it compresses the fuel located in the pump work chamber 48 and displaces it into the high-pressure channel 10.
• the piezo actuator 34 is energized so that it changes its length and moves the control piston 32 against the force of the return spring 36 into the spring chamber 38.
• the fuel thus displaced from the spring chamber 38 increases the fuel pressure in the control chamber 30, so that the force on the end face 28 of the valve member 14 also increases accordingly to such an extent that it becomes greater than the force of the spring 27 regulated so that the control edge 25 dips into the throttle section 21 without the valve sealing surface 24 coming into contact with the valve seat 22.
• the fuel which can flow practically unthrottled from the high-pressure duct 10 via the high-pressure chamber 16 into the low-pressure chamber 18 at the start of the delivery movement of the pump piston 42, is now throttled through the throttle gap 23, so that a certain pre-injection pressure is established in the high-pressure chamber 16 and in the high-pressure duct 10 , which depends on how large the delivery rate of the pump piston 42 and how strong the throttling effect of the throttle gap 23.
• the throttling of the fuel pressure takes place in the throttle gap 23, so that the pressure in the fuel flow to the low pressure chamber 18 has already dropped when the fuel reaches the valve sealing surface 24. Therefore, there are only slight hydraulic forces on the valve sealing surface 24 and therefore also no forces that are difficult to control in the opening direction on the valve member 14.
• the pre-injection pressure in the high-pressure channel 10 and thus also in the pressure chamber 8 of the injection valve 1 is matched to the force of the closing spring 5, which holds the valve needle 3 in the closed position, so that the hydraulic force on the valve needle 3 is sufficient to close the valve needle 3 in the open position move and so open the injection openings 7. Since the pre-injection pressure is clearly below the maximum injection pressure, only a small amount of fuel is injected into the combustion chamber (pre-injection).
• the control piston 32 further increases the pressure in the control chamber 30 through the piezo actuator 34 until the valve member 14 comes into contact with the valve sealing surface 24 on the valve seat 22 due to the hydraulic force on the end face 28.
• the connection of the high-pressure chamber 16 to the low-pressure chamber 18 is interrupted, and the maximum pressure that can be generated by the pump piston 42 acts in the high-pressure channel 10 and in the pressure chamber 8.
• the injection is now carried out with a significantly higher injection pressure and thus with a higher injection rate.
• the main injection can be continued at the longest until the pump piston 42 has reached its lower reversal point and all the fuel that can be displaced by the pump piston 42 is conveyed into the high-pressure channel 10. Most of the time, however, the main injection is terminated much earlier, since less fuel is required in the combustion chamber and secondly a precisely defined end of the injection is aimed for. This is done in that the pressure in the control chamber 30 is reduced, controlled by the piezo actuator 34. The force of the spring 27 now predominates. the opposite of the hydraulic force on the end face 28 of the valve member 14, and the valve member 14 is moved in the direction of the control chamber 30 until it comes to rest on the wall of the control chamber 30.
• the high-pressure channel 10 is also connected to the low-pressure chamber 18 via the high-pressure chamber 16, so that the pressure in the pressure chamber 8 also drops and the valve needle 3 closes the injection openings 7 by the closing spring 5.
• the remaining amount of fuel that the pump piston 42 delivers after the end of the injection before it reaches the lower reversal point is delivered into the low-pressure line 60 and from there via the pressure relief valve 64 into the tank 66.
• valve member 14 The arrangement of the valve member 14, the control piston 32 and the pump piston 44 with respect to the injection valve 1 shown in the drawing is not required in this way for the function of the pump-nozzle unit. Provision can also be made for orienting one or more of these elements in a different way, if it should be expedient.
• the valve member 14 and thus the bore 26 can also be arranged perpendicular to the longitudinal axis of the nozzle needle 3.

Landscapes

• Engineering & Computer Science (AREA)
• Chemical & Material Sciences (AREA)
• Combustion & Propulsion (AREA)
• Mechanical Engineering (AREA)
• General Engineering & Computer Science (AREA)
• Physics & Mathematics (AREA)
• Electromagnetism (AREA)
• Fuel-Injection Apparatus (AREA)

Applications Claiming Priority (3)

Publications (1)

Family

ID=7642257

Family Applications (1)

Country Status (8)

Families Citing this family (9)

Family Cites Families (11)

• 2000
  • 2000-05-16 DE DE10023960A patent/DE10023960A1/de not_active Withdrawn
• 2001
  • 2001-05-03 EP EP01940207A patent/EP1283954A1/de not_active Withdrawn
  • 2001-05-03 KR KR1020027000571A patent/KR20020038691A/ko not_active Application Discontinuation
  • 2001-05-03 CN CN01801288A patent/CN1380940A/zh active Pending
  • 2001-05-03 BR BR0106642-0A patent/BR0106642A/pt not_active Application Discontinuation
  • 2001-05-03 JP JP2001584733A patent/JP2003533637A/ja active Pending
  • 2001-05-03 US US10/030,984 patent/US20020113140A1/en not_active Abandoned
  • 2001-05-03 WO PCT/DE2001/001680 patent/WO2001088367A1/de not_active Application Discontinuation

Non-Patent Citations (1)

Also Published As

Similar Documents

Legal Events