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
  • F02M65/00—Testing fuel-injection apparatus, e.g. testing injection timing ; Cleaning of fuel-injection apparatus
  • F02M65/007—Cleaning
  • F02M65/008—Cleaning of injectors only
• • 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
  • F02M47/00—Fuel-injection apparatus operated cyclically with fuel-injection valves actuated by fluid pressure
  • F02M47/02—Fuel-injection apparatus operated cyclically with fuel-injection valves actuated by fluid pressure of accumulator-injector type, i.e. having fuel pressure of accumulator tending to open, and fuel pressure in other chamber tending to close, injection valves and having means for periodically releasing that closing pressure
  • F02M47/027—Electrically actuated valves draining the chamber to release the closing 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
  • F02M65/00—Testing fuel-injection apparatus, e.g. testing injection timing ; Cleaning of fuel-injection apparatus

Definitions

• the invention relates to a method according to the preamble of claim 1.
• the invention is particularly important in the case of common rail injectors.
• Such an injector which itself does not cause an increase in pressure, but is supplied directly with the fuel which is under pressure to be injected into the engine, in particular a diesel engine, reacts sensitively to air components in the medium processed by the injector.
• this medium is diesel fuel
• the test medium used to measure and test the injector in the test field is usually not diesel fuel, but a hydraulically similar material that is preferably non-combustible.
• Air pockets in the injector, which are used when filling Medium are available before start-up, must over the volume flow of the return flow of the medium, which during normal operation z. B. results from leakage quantities and / or from the actuation of a control valve to be flushed out to a low pressure connection (leakage connection) of the injector.
• the gaseous air has a much greater compressibility than the liquid medium, and as a result the dynamic damping behavior in the injector, in particular in a solenoid valve, is influenced in an unreproducible manner and has a direct effect on the injection quantity. This makes measurements in the test field more difficult.
• the existing gaseous air also leads to unreproducible injection processes, which for a short time results in an uncomfortable driving experience and non-compliance with the required exhaust gas values may have.
• Dissolved air contained in the medium is not considered to be a nuisance in the present application as long as the air remains dissolved during the entire operating state of the injector and does not become gaseous.
• the solenoid valve mentioned can be, in particular, a control valve which uses an outflow throttle to discharge medium from a
• Control chamber of a stroke-controlled injector releases to initiate an injection process and locks to end the injection process.
• Various movable and immovable parts of the solenoid valve (see, for example, Fig. 2: armature, at least one spring, closure element to be actuated to release the outflow; immobile guidance of the armature) are arranged in a functional space.
• the named functional space and the parts of the control valve contained in it have numerous edges and projections which tend to hold air bubbles, provided they do not exceed a certain size, so that it takes considerable time (many seconds to about 1 minute) in normal operation can last until this functional space contains so little air in the gaseous state that there is practically no interference with the function of the internal combustion engine or during the measurement.
• the functional space is generally directly connected to a low-pressure connection of the injector, that is to say without the interposition of special shut-off elements.
• ambient pressure which is simplistically regarded as 1 bar (absolute) or 0 bar (relative)
• at least a slight overpressure for example 0.5 bar
• the control valve of which is actuated by a piezo actuator, preferably via a hydraulic coupler. Even with such an injector, it can be advantageous to make it air-free with the invention.
• the invention has for its object to bring about the operational readiness of the injector despite the gaseous air contained therein in the liquid medium, that is to say with a pneumatic / hydraulic filling of the injector.
• the pressure drop should not be so great that the vapor pressure of the liquid medium or of parts thereof is reached or fallen below.
• the rapid discharge of the return quantity enriched with gas bubbles can be accelerated by flushing away with an air-free medium at a pressure which is considerably lower than that of the common rail pressure.
• this medium can be fuel originating directly from the fuel tank.
• the device according to the invention according to claim 4 has devices for connecting an injector to a source of high pressure of the medium and to a vacuum connection.
• a control device with control connections of switching valves is advantageously coupled and further advantageously with a control circuit for opening and closing the injection openings of the injector.
• Fig. 1 is a hydraulic block diagram of the arrangement for removing
• Air inclusions from a common rail injector this arrangement being used both in the test field when the injection system is commissioned for the first time by the automobile manufacturer, or in a well-equipped repair shop for automotive engineering,
• Fig. 2 shows a longitudinal section through a known stroke-controlled injector for diesel fuel with a solenoid valve, the pressure in a control chamber for actuating a valve piston via an outlet throttle
• Fig. 3 is a timing diagram of the control of the valves V1 to V4.
• the arrangement 1 shown in FIG. 1 schematically shows an injector 2 mounted in the arrangement for common rail operation with a high pressure connection 3 for the liquid test medium that is free of gaseous air. This can be supplied from a connection 5, at which the test medium is available under high pressure, via a pipeline 6.
• the injector 2 has been used in the test field in the completely empty state, that is to say only filled with air, in the arrangement 1 shown, or else with mixed filling (air and test medium), for. B. in repeat tests.
• the injector has a connection 7 for electrically actuating a magnetic control valve 8, which when actuated via an outlet throttle 9 reduces the pressure in a control chamber 10 (FIG. 2) in order to control the opening of injection openings 11 by means of a valve piston 12.
• Leakage quantities depending on the design of the injector, also a larger return flow quantity of the injector, which occurs during operation, flow out via a connection 13 (low-pressure connection, leakage connection) of the injector.
• this connection is not directly connected to a pipeline, for example, for returning it to the fuel tank, but to an adaptation head 14, which makes it possible to connect the connection 13 to other connections of the arrangement.
• a vacuum pump 16 which is connected via a pipe 17 and a pipe branch 18 to a pipe 19 connected to the adaptation head; in addition, a container 20 for receiving the above-mentioned return flow quantity, which is connected to the pipe branch 18 via a pipeline 21.
• a low-pressure connection 22 for a low-pressure medium here referred to as flushing medium, is provided, which is fed via a pipe 24 and a throttle 25 to a connection of the adaptation head 14 opposite the pipe 19.
• flushing medium is provided, which is fed via a pipe 24 and a throttle 25 to a connection of the adaptation head 14 opposite the pipe 19.
• switching valves namely a switching valve V1 in line 17, a switching valve V2 in line 24, a switching valve V3 in line 21 and a switching valve V4 in line 6.
• Electrical control connections of the switching valves are included connected to a control device that controls the execution of the method.
• the functional sequence is explained on the basis of the curve profiles shown in FIG. 3, which designate the closed line with their base line and the open state of the assigned switching valve with their line running above the base line.
• the negative pressure generated by the vacuum pump 16 acts via the adaptation head 14 at the connection 13 of the injector and also on its hydraulic internal volume, insofar as it is connected to the connection 13, in particular on the space in which the control valve is located.
• the vacuum sucks the test medium out of the injector via the pipelines 17 and 19, the adapter head 14 and the connection 13, although there may be a lot of air that is not present in the form of bubbles in the first process. Any air bubbles originally present have increased due to the vacuum compared to the original state (when the pressure is reduced, for example, doubled in diameter from 1 bar to 0.1 bar) and can no longer get caught on any projections so easily they are flushed out by the constant return flow produced by the injector.
• a control signal is fed to the electrical connection 7 via a control circuit 7 'coupled to the control device mentioned, which controls the injector in the example in the manner customary for the operation of an internal combustion engine, in the example with 1000 electrical pulses per minute, so that the control valve 8 per minute 1000 opening and closing operations. (This is much faster than, for example, the switching frequency of the control valve 2.)
• leakage fluid and control fluid which arises when the valve piston 12 is lifted, flows out through the connection 13 and, due to the negative pressure present in the area of the control valve, rinses air bubbles which are enlarged compared to normal operation.
• the rinsed air bubbles get into the adapter head 14 and are there at one preferred embodiment of the method is flushed out of the adaptation head by flushing medium which is released a total of 3 times by the valve V2 in the example shown, which supports the removal of air from the vicinity of the injector.
• the vacuum pump 16 is designed such that it sucks off both air and the medium or fuel that is produced.
• the vacuum pump 16 only sucks in air; the mixture of air bubbles and liquid medium flowing vertically upwards through line 17 in the example, still under vacuum, arrives from above into a collecting container, where the liquid medium collects, and the vacuum pump is connected above the collecting container and therefore does not come in contact with the liquid medium.
• the collecting container mentioned must be emptied from time to time.
• Low-pressure connection 13 of the injector 2 which is now still sufficiently air-free, is supplied to the collecting container 20 through the valve V4, as is provided in normal operation in the motor vehicle, and can be measured (quantified) as required when the medium is further supplied to the high-pressure connection 3.
• a measurement of the properties of the injector can now be carried out in the test field, or it is now air-free in a combustion injection valve freshly used in an internal combustion engine and the arrangement of the internal combustion engine used to make it air-free can be made according to it Shutdown are removed and standard connections of the internal combustion engine, which had to be disconnected to attach the measuring device, are restored.
• measuring devices or measuring points for the vacuum, the low-pressure flushing medium and the high-pressure test medium symbolized as pointer instruments are also provided, by means of which the activity of the system can be monitored and the measured values of which can be recorded in a log.
• t1 absolute pressure 0.1 bar, air bubble volume 10
• t2 absolute pressure 2.6 bar, air bubble volume 0.38
• t3 absolute pressure 0.1 bar
• t4 absolute pressure 2.6 bar, air bubble volume 0.38
• t5 absolute pressure 0.1 bar, air bubble volume 10
• t6 absolute pressure 4 bar, air bubble volume 0.25.
• FIG. 3 is only to be understood as an illustration, in practice more rinsing processes (or not a single rinsing process) and several repetitions of the process shown can be carried out.
• injectors e.g. those which bring fuel from a relatively low pressure to the injection pressure via a built-in compressor, according to the invention to free air pockets.
• the invention can also be applied to other types of control valves with utility, particularly for example a control valve actuated by a piezo actuator, although due to the lack of the above-mentioned positive feedback effect on the electromagnetic valve, the latter may not be as strongly affected by the presence of air bubbles is influenced in its function.
• a control valve actuated by a piezo actuator although due to the lack of the above-mentioned positive feedback effect on the electromagnetic valve, the latter may not be as strongly affected by the presence of air bubbles is influenced in its function.
• it may be particularly disruptive that, after starting up a largely air-filled injection valve, foaming can initially occur in the area in which the moving parts of the control valve are located, making measurement difficult or impossible.
• Such injectors which require the presence of a hydraulic 'coupler a counter-holding pressure at the leakage connection of, for example 10 bar during normal operation can, freed in the manner described here of entrapped air and are usually exposed to the mentioned low pressure of 0.1 bar, which is not used for very long.

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

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• 2003
  • 2003-03-30 DE DE10314454A patent/DE10314454B4/de not_active Expired - Fee Related
  • 2003-09-29 JP JP2004570021A patent/JP2006514212A/ja not_active Withdrawn
  • 2003-09-29 WO PCT/DE2003/003236 patent/WO2004088125A1/de not_active Application Discontinuation
  • 2003-09-29 US US10/551,116 patent/US20060213485A1/en not_active Abandoned
  • 2003-09-29 EP EP03753329A patent/EP1611345A1/de not_active Withdrawn

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