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
  • F02M59/20—Varying fuel delivery in quantity or timing
  • F02M59/34—Varying fuel delivery in quantity or timing by throttling of passages to pumping elements or of overflow passages, e.g. throttling by means of a pressure-controlled sliding valve having liquid stop or abutment
• • 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
  • F02M37/00—Apparatus or systems for feeding liquid fuel from storage containers to carburettors or fuel-injection apparatus; Arrangements for purifying liquid fuel specially adapted for, or arranged on, internal-combustion engines
  • F02M37/0011—Constructional details; Manufacturing or assembly of elements of fuel systems; Materials therefor
  • F02M37/0023—Valves in the fuel supply and return system
  • F02M37/0029—Pressure regulator in the low pressure fuel system
• • 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
  • F02M37/00—Apparatus or systems for feeding liquid fuel from storage containers to carburettors or fuel-injection apparatus; Arrangements for purifying liquid fuel specially adapted for, or arranged on, internal-combustion engines
  • F02M37/0047—Layout or arrangement of systems for feeding fuel
  • F02M37/0052—Details on the fuel return circuit; Arrangement of pressure regulators
• • 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
  • F02M63/00—Other fuel-injection apparatus having pertinent characteristics not provided for in groups F02M39/00 - F02M57/00 or F02M67/00; Details, component parts, or accessories of fuel-injection apparatus, not provided for in, or of interest apart from, the apparatus of groups F02M39/00 - F02M61/00 or F02M67/00; Combination of fuel pump with other devices, e.g. lubricating oil pump
  • F02M63/0001—Fuel-injection apparatus with specially arranged lubricating system, e.g. by fuel oil
• • 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
  • F02M63/00—Other fuel-injection apparatus having pertinent characteristics not provided for in groups F02M39/00 - F02M57/00 or F02M67/00; Details, component parts, or accessories of fuel-injection apparatus, not provided for in, or of interest apart from, the apparatus of groups F02M39/00 - F02M61/00 or F02M67/00; Combination of fuel pump with other devices, e.g. lubricating oil pump
  • F02M63/02—Fuel-injection apparatus having several injectors fed by a common pumping element, or having several pumping elements feeding a common injector; Fuel-injection apparatus having provisions for cutting-out pumps, pumping elements, or injectors; Fuel-injection apparatus having provisions for variably interconnecting pumping elements and injectors alternatively
  • F02M63/0225—Fuel-injection apparatus having a common rail feeding several injectors ; Means for varying pressure in common rails; Pumps feeding common rails

Definitions

• the invention relates to an overflow valve for a fuel injection system and a fuel injection system with overflow valve, in particular a common rail injection system, having the features of the preamble of claim 1.
• Fuel injection systems in particular common-rail injection systems, have a high-pressure pump for generating pressure.
• the high-pressure pump is supplied with fuel.
• the control of the amount of fuel to be delivered to high pressure via a arranged in the low-pressure circuit metering unit.
• the leakage of the metering unit leads inherently in operating points with zero promotion to an impermissible increase in the pressure in a high-pressure pump downstream high-pressure accumulator (rail), since the leakage amount is promoted to high pressure.
• there is a zero feed throttle in the low pressure circuit through which the leakage quantity of the metering unit can flow.
• an overflow valve is arranged which has an axially displaceable valve piston, via the axial displacement of which at least one outflow opening can be opened or closed. Due to the overflow valve, excess fuel conveyed by the prefeed pump can be deactivated relative to the amount of fuel to be delivered by the high-pressure pump.
• the present invention seeks to provide an overflow valve for a Kraftstoffeinspritzsys- Specify a particular, a common rail injection system, which allows for elimination of the separate zero feed throttle.
• the proposed fuel injection system comprises a prefeed pump, by means of which fuel from a fuel tank is supplied to a high-pressure pump, a metering unit for controlling the at least one pump element of the high-pressure pump to be supplied via an inlet fuel and an overflow valve with an axially displaceable valve piston, on the axial displacement at least one Outflow opening is releasable or closable.
• a axially extending flow channel is formed in the valve piston with a cross-sectional constriction, wherein in the region of the cross-sectional constriction, a substantially radially extending bore opens into the flow channel, via which the flow channel with the inlet downstream of the metering unit is hydraulically connectable.
• the reaching into the inlet to the high-pressure pump leakage quantity of the metering unit can therefore flow off via the formed in the valve piston of the overflow valve flow channel.
• the cross-sectional constriction of the flow channel supported in the manner of a Venturi nozzle the outflow of the leakage amount, since in the opening into the flow passage bore a negative pressure is effected, which causes a suction of the leakage amount.
• By ensuring the outflow of the leakage amount of the metering unit at zero delivery operation via the overflow valve can be dispensed with the formation of a separate zero-feed throttle. This simplifies the structure of the fuel injection system and costs can be reduced.
• the flow channel may have two opposite conical sections, which are set with their smaller diameters directly or via an intermediate cylindrical section.
• the inner contour of the flow channel may also be spherical, with the inner contour preferably bulging convexly inwards.
• the radius of the spherically formed inner contour can be chosen differently in the flow direction before and behind the cross-sectional constriction. The same applies with respect to the respective cone angle, provided that the cross-sectional constriction is formed by means of two opposite cone-shaped sections.
• the valve piston is designed in several parts and comprises at least one sleeve-shaped component for forming the flow channel.
• the sleeve-shaped component can be processed separately before joining the parts of the valve piston, which facilitates the formation of the flow channel. As a result, the production costs and the production costs are further reduced.
• the sleeve-shaped component is pressed to form the flow channel in a central bore of the valve piston.
• the central bore for receiving the sleeve-shaped component may for example be formed in a further sleeve-shaped component.
• the central bore is at least partially formed as a flow channel and designed as a through hole.
• the through-bore is preferably flowed through by fuel permanently and thus allows a constant lubrication and / or cooling of the high-pressure pump.
• the fuel flowing through the valve piston is supplied to a return via an outflow opening.
• the discharge opening is independent of the respective axial position of the valve piston permanently released, so that a continuous flow is guaranteed.
• An axial displacement of the valve piston and consequently the complete opening of the overflow valve is effected only when a predetermined limit pressure is exceeded (one-stage design of the overflow valve).
• the overflow valve can also be designed as a two-stage valve. The release of the discharge opening for returning the lubricating and / or cooling amount (first stage) then requires an axial displacement of the valve piston. With progressive axial displacement of the valve piston, the release of at least one further outflow opening (second stage) takes place.
• the central bore of the valve piston is at least partially formed as a flow channel and designed as a blind hole.
• the blind hole is preferably hydraulically connected via a transverse bore with at least one outlet opening.
• a permanent or, depending on the axial position of the valve piston a temporary hydraulic connection can be made via the transverse bore, so that a one- or two-stage concept can be realized.
• the central bore itself can serve as a flow channel.
• the central bore or the flow channel can be formed as a through hole or blind hole.
• single-stage, as well as two-stage valves can be realized.
• valve piston is received in a housing part which has at least one substantially radially extending bore.
• the essentially radially extending bore is preferably arranged in the housing part in such a way that, optionally in dependence on the axial position of the valve piston, it permits a hydraulic connection of the flow passage with a supply or return.
• the housing part may for example be sleeve-shaped and insertable into a bore of the housing of the high-pressure pump.
• the housing of the high pressure pump can form the housing part.
• the at least one substantially radially extending bore serves as a discharge opening, over which surface of the flow channel of the valve piston is hydraulically connectable to a return.
• the hydraulic connection may require an axial displacement of the valve piston to release the discharge port.
• the hydraulic connection can also be permanent, for example, to ensure a constant lubrication and / or cooling of the high-pressure pump.
• the design as a two-stage valve requires the formation of at least two substantially radially extending bores through which fuel can flow.
• at least one further substantially radially extending bore may be formed, which is hydraulically connectable to the substantially radially extending bore of the valve piston in order to first supply the leakage quantity of the metering unit to the flow channel and via the flow channel to a return line.
• a circumferential groove for forming an annular space between the valve piston and the housing part is preferably formed on the valve piston and / or in the housing part.
• the hydraulic connection of the holes is thus independent of the rotational position of the valve piston relative to the housing part.
• a circumferential groove can also be formed on the sleeve-shaped component of a two-part valve piston.
• valve piston is acted upon in the closing direction by the spring force of a spring. While the opening of the overflow valve is effected solely by the hydraulic pressure, the return of the valve piston to its initial position via the spring force is a spring.
• the spring is preferably on the one hand on the valve piston, on the other hand-at least indirectly-supported on the housing part, which surrounds the valve piston.
• Fig. 3 is a sectional view through the valve piston of the overflow valve of
• Fig. 4 is a schematic representation of a fuel injection system with an alternative low-pressure circuit according to the invention.
• FIG. 5 shows a longitudinal section through the overflow valve of FIG. 4, which shows a sleeve-shaped component of the valve piston in a sectional view.
• the fuel injection system shown in Fig. 1 comprises a low pressure circuit.
• Components of the low pressure circuit are a prefeed pump 1, which sucks fuel from a fuel tank 2 and a high-pressure pump 3, a arranged between the prefeed pump 1 and the high-pressure pump 3 metering unit 4 for flow control and a spill valve 7, whose task is the pressure in front of the metering unit 4 as constant as possible.
• the overflow valve 7 opens, so that fuel can flow off via a return 17.
• the fuel was already passed as a lubricant and / or coolant through the low pressure region of the high pressure pump.
• the overflow valve shown has a further connection to a return line 17, via which fuel can flow off continuously.
• the drainage is throttled.
• the metered via the metering unit amount of fuel is fed via an inlet 5 at least one pump element 6 of the high-pressure pump 3. In the present case two pump elements 6 are shown.
• the fuel is conveyed to high pressure and then fed to a high-pressure accumulator 22.
• the high-pressure accumulator 22 has a plurality of connections 23 for fuel injectors (not shown), by means of which rather, the fuel in the combustion chamber of an internal combustion engine (not shown) can be injected.
• prefeed pump 1, metering unit 4 and overflow valve 7 can be integrated into the high-pressure pump 3 or attached thereto.
• a common housing 24 is indicated schematically by the dot-dash-dot line.
• the housing part 15 With which it is inserted in a bore (not shown) of the housing 24 of the high-pressure pump 3.
• an axially displaceable valve piston 8 is accommodated, in which a continuous flow channel 10 is formed (see FIG. 3).
• the flow channel 10 has a spherically shaped inner contour, so that a cross-sectional constriction 11 is formed in the manner of a Venturi nozzle.
• a radially extending bore 12 is guided by the valve piston 8, which connects the flow channel 10 with an annular space 19 which is formed between the housing part 15 and the valve piston 8.
• the annular space 19 is formed by a circumferential groove 18 provided in the housing part 15. Another circumferential groove 18 is also the outer circumference side on
• Valve piston 8 is provided, which also communicates with the annular space 19.
• a formed in the housing part 15 radially extending bore 16 opens into the annular space 19 and is also in hydraulic communication with the inlet 5 of the high-pressure pump 3. The entering into the inlet 5 leakage amount of the metering unit 4 can therefore via the bore 16, the annular space 19, the
• the discharge opening 9 is also designed as a radially extending bore in the housing part 15. Due to the hydraulic connection of the flow channel 10 with the inlet 5 of the high-pressure pump 3, a separately designed zero-delivery throttle is dispensable.
• the flow channel 10 is designed in the manner of a Venturi nozzle, that is to say that it has a cross-sectional constriction 11. In the region of the cross-sectional constriction 11, the bore 12 opens into the flow channel 10. If now the flow channel 10 is traversed by fuel, this has to
• a negative pressure is created, which is the drain supports the leakage quantity.
• the amount of leakage is fed together with the fuel to a discharge opening 9 and here a return 17.
• the discharge opening 9 is permanently in hydraulic communication with the flow channel 10, so that continuous flow of fuel through the valve piston 8. As a result, a constant lubrication and / or cooling of the high-pressure pump 3 is ensured.
• FIG. 5 An alternative embodiment of an overflow valve 7 according to the invention for a low-pressure circuit is shown in FIG. 5.
• the valve piston 8 is designed in this case in two parts.
• the flow channel 10 is formed by a sleeve-shaped component 13 which is pressed into a central bore 14 of the valve piston 8.
• the central bore 14 is designed as a blind hole, so that the valve piston 8 is not continuously flowed through by a lubricating and / or cooling amount.
• an axial displacement of the valve piston 8 (first stage) is required.
• a progressive axial displacement of the valve piston 8 then causes the release of at least one further outflow opening 9 and thus the complete opening of the overflow valve 7 (second stage).
• the overflow valve of FIG. 5 is designed as a two-stage valve.
• At least one further radially extending bore 16 in the housing part 15 is formed, which serves as an inlet or is hydraulically connected to the inlet 5 of the high-pressure pump 3.
• the bore 16 is hydraulically connectable to the radial bore 12 of the valve piston 8, which opens in the region of the cross-sectional constriction 1 1 in the flow channel 10. Due to the two-part design of the valve piston 8 and the bore 12 is made in two parts.
• the sleeve-shaped component 13 has on its outer circumference a circumferential groove 18 for forming an annular space 19.
• a hydraulic connection of the bore 12 with the bore 16 initially requires an axial displacement of the valve piston 8.
• the axial displacement of the valve piston 8 is effected in the opening direction of the valve via the hydraulic pressure p (see arrow in Fig. 5).
• the valve piston 8 is acted upon by the spring force of a spring 20, which is supported on the one hand on the valve piston 8, on the other hand on a closure plug 21 which is pressed into the housing part 15.
• the spring 20 thus causes the return of the valve piston.
• FIG. 4 shows the overflow valve 7 of FIG. 5 as part of a Kraftstoffeinspitzsystems or a low pressure circuit of a fuel injection system. This differs from that of FIG. 1 only in that the overflow valve 7 is designed as a two-stage valve.

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

Applications Claiming Priority (2)

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• 2011
  • 2011-01-31 DE DE201110003362 patent/DE102011003362A1/de not_active Withdrawn
  • 2011-12-30 WO PCT/EP2011/074320 patent/WO2012103998A1/de not_active Ceased
  • 2011-12-30 EP EP11802968.5A patent/EP2670969B1/de active Active
  • 2011-12-30 CN CN201180066233.6A patent/CN103339364B/zh active Active

Non-Patent Citations (1)

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