`
`UK Patent Application (19> GB <11) 2 227 076aA
`
`{43) Date 01 A publication 18.07.1990
`
`(52) UK CLtEcifion K)
`m W61
`”13 51833
`
`{56) Documents cited
`None
`
`(58) Field of search
`UK CLIEdifion J) F2V W81, can NGK1
`INT CL‘ F020, 6053
`
`(Incorporated in the Federal Republic of Germany)
`
`Panther: 10 ED 50.1099 Stuttgart 10,
`Fido“! Republic of Germany
`
`(72)
`
`inventors
`Joachlm Berger
`Manfred Blrlt
`‘l'homu Kuottner
`Dieter Sober
`Hermann Kull
`
`
`(51)
`INT CL'
`(21) Application No aszssms
`
`
`case was
`
`(22) Date of filing 10.11.1939
`(30) Priority data
`
`(81) scene?
`(32) 11.11.1935
`(33} DE
`
`(71) Applicant
`Robert Bosch Gmbt-t
`
`
`
`
`
`
`
`
`(74) Agent andtcr Address tor Service
`Dr Walther Wolff a Go
`5 Buckingham Gate. London. SW1E EJP,
`United Kingdom
`
`
`
`(54) Monitoring the integrity of e satety shut-oft device
`
`(57) A method of monitoring the integrity of a redundant safety sh ut-oft valve {16} in an internal combustion engine
`comprises the steps, carried out during steady idling operation as indicated by maintenance of prescribed boundary
`conditions. of reducing the teed pressure and the injected quantity to a fuel quantity setting mechanism by closing at the
`valve (15) by means of test circuitry (19), and of observing the reaction clan idling reg utatcr resulting theretrom. A rise in
`the output magnitude of the regulator, or a resultant greater fuel pump regulating travat or setting angle, is evaluated as an
`indication confirming the correct tuntion of the valve.
`
`
`
`V91012838'5)
`
`VW EX1017
`
`US. Patent No. 6,588,260
`
`VW EX1017
`U.S. Patent No. 6,588,260
`
`
`
`
`
`
`
`(T
`
`_ 1 _
`
`MONITORING THE INTEGRITY OF A SAFETY SHUT-OFF DEVICE
`
`sailiet?co17é:
`
`The present invention relates to a method of monitoring the integ—
`
`rity of a safety shut-off device in the form of an electromagnetic
`
`valve in an internal combustion engine and to monitoring means for such
`
`a purpose.
`
`In safety equipment for an internal combustion engine with compress-
`
`ion ignition, it is known (DE-OS 33 01 742)
`
`to continuously detect
`
`signals concerning the operation of the engine, such as accelerator pedal
`
`setting, calculated target value of fuel
`
`injection regulating travel,
`
`10
`
`engine Speed, brake pedal setting and so forth, and to provide a correct-
`
`ed regulating travel target value by minimum value selection,
`
`the
`
`corrected value being fed to the setting regulator of an electronic
`
`diesel regulation (EDC) system. This corrected target value at the same
`
`time serves for ascertaining regulating deviation with the inclusion of
`
`15
`
`a regulating travel actual value signal that has been reported back.
`
`If preset limits are exceeded,
`
`the safety equipment reacts either by
`
`switching-off the injection pump, switching off current supply to the
`
`end stage of_the setting regulator or switching on a redundant sub-
`
`stitute function. However,
`
`in some circumstances problems can arise
`
`20
`
`in this known equipment, because not all possible boundary conditions
`
`are included in the detection of the safety conditions and separate
`
`checking of the electromagnetically operated fuel feed shut-off valve
`
`[ELAB) does not take place.
`
`In a known fuel
`
`injection pump for diesel engines (DE-US 29 45 484),
`
`25
`
`a pump piston arranged in the housing of the fuel
`
`injection pump
`
`is
`
`set into reciprocating and rotary movement, wherein fuel
`
`from the
`
`interior housing space — forming the suction space — of the pump flows
`
`to a conveying element.
`
`From there the fuel passes according to the
`
`
`
`set quantity into the pressure ducts leading to the engine cylinders.
`
`A safety valve is arranged in the connecting duct between the suction
`
`space and the conveying element and interrupts fuel feed from the
`
`suction space to the element if certain safety conditions are exceeded.
`
`It is also known to use electrical setting mechanisms (DE-OS
`
`35 31 198), which are driven by electrical signals, for electronic reg-
`
`ulation of the operation of compression ignition internal combustion
`
`engines, thus diesel engines, wherein a central control device in
`
`place of mechanical fuel metering and regulating systems produces the
`
`10
`
`required setting signals. Although mechanical fuel metering Systems
`
`in diesel engines are reliable in respect of-their faultjsecurity,
`
`in '
`
`some circumstances they are less able to take into account the multi-
`
`plicity of different operating conditions and environmental
`
`influences:
`
`The use of electronic components in conjunction with electronic
`
`15
`
`diesel regulation makes comprehensive safety, monitoring and sub-
`
`stitute measures desirable when the individual assemblies on their own
`incorporate capabilities for fault recognition and, optionally also,
`
`fault exclusion. Thus, it is known in the usual series and distributor
`
`pumps for diesel
`
`injection in electronic diesel control
`
`to provide an
`
`20
`
`electrical cut-off device in the form of an electromagnetic cut-off
`
`valve; this interrupts the feed of diesel fuel
`
`in the case of a defect
`
`in the control device,
`
`in the case of defective transmitters and in
`
`the case of disturbances or defects in the cabling or in the injectiOn
`
`pump, and thus makes possible a controlled shut-down of the engine.
`
`25
`
`Since this electrical cut-off device makes redundant shutting-
`
`down possible in response to potentially dangerous operational states
`
`such as independent accelerating or racing of the diesel engine,
`
`the
`
`
`
`safety of the system very much depends on the function of the cut-off
`
`valve.
`
`For this reason, a test of the valve is desirable during
`
`normal
`
`travel operation, which test as far as possible should not be
`
`apparent to the driver, for example through drop in engine speed.
`
`There is therefore a need,with respect to the significance that _
`
`an electromagnetic shut-off valve has as redundant safety device in
`
`an engine,
`
`to be able to monitor its correct function, preferably
`
`unnoticeably,
`
`in normal
`
`travel operation and to react, for example
`
`with an alarm indication, on detection of a fault, There is, however,
`
`10
`
`the consideration that the valve is part of the fuel supply system
`
`and separate checking of its function may switch off-the engine.
`
`It :
`
`is therefore not possible to check the valve simply
`
`in a time-
`
`controlled manner,
`
`thus at preset time intervals during normal operat-
`
`ion of the vehicle, since this checking could lead to the engine cutt—
`
`15
`
`ing out.
`
`On the other hand, a defective valve cannot be recognised by the
`driver, because not only is the current supply to the possibly defect—
`
`ive valve interrupted when the voltage supply is switched off, but
`
`the voltage supply for the quantity setting mechanism and the other
`
`20
`
`components is also switched off. Moreover,
`
`the driver or user of a
`
`motor vehicle equipped with a safety cut-off valve is unlikely to
`
`monitor it continuously or wish to be involved in constantly checking
`
`safety components in the fuel quantity regulation.
`
`According to a first aspect of the present
`
`inventiOn there is
`
`25 provided a method of mmitmnng
`
`the integrity of an electromagnetic
`
`safety valve responsive to a fault condition to cut off fuel feed in
`
`a vehicle internal combustion engine with electronically regulated
`
`
`
`fuel metering,
`
`the method comprising the steps of completely or partial-
`
`ly interrupting fuel feed by way of the valve during steady idling of
`
`the engine in normal vehicle travel operation and evaluating consequent
`
`change in an idling regulating parameter as an indication of correct
`
`functioning of the valve.
`
`"
`
`According to a second aspect of the present invention there is
`
`provided monitoring means for monitoring the integrity of an electro-
`
`magnetic safety valve responsive to a fault condition to cut off fuel
`
`feed in a vehicle internal combustion engine with electronically reg-
`
`10
`
`ulated fuel metering,
`
`the monitoring means comprising test circuit
`
`means to detect:steady idling of the engine—and cause operation of the
`
`valve for complete or partial interruption of fuel feed during such
`
`steady idling and to evaluate consequent change in an idling regulat—
`
`ion parameter as an indication of correct functioning of the valve.
`
`15
`
`A method exemplifying and monitoring means embodying the invention
`
`may have the advantage of being able to check the safety cut-off valve
`in-its function effectively during operation of the engine,
`in partic-
`
`ular without interruption of or disturbance in the vehicle travel or
`
`a noticeable drop in engine rotational speed. There is selection
`
`20
`
`of an instant, suitable for this checking,
`
`in the operational course
`
`of the engine and a particular reaction which must then occur is
`
`detected. Nevertheless, the test function is still such that it can
`
`ascertain whether the valve lets fuel
`
`through in the closed state or
`
`whether it remains in the opened state and has, for example, Seized
`
`25
`
`in its seating.
`
`The steady idling operation of the engine represents a particular-
`
`ly suitable instant for the checking. The test function can be
`
`
`
`performed during each steady idling operation.
`
`It can, however, be
`
`arranged to check the valve function only after a given number of
`
`occurrences of the steady idling operation.
`
`It is feasible to so construct the valve that it is reversible
`
`5
`
`or to so structure peripheral conditions that the reversibility of
`
`the valve results.
`
`It is advantageous that the monitoring means may be able to be
`
`realised through small additional circuitry in an electornic control
`
`device for fuel regulation or entirely without additional hardware
`
`10
`
`through a corresponding software program structuring in the electronic
`
`'control region, since the control device usually has the form of a
`
`-
`
`small computer or microprocessor with storage.
`
`No additional
`
`inputs
`
`at the control device need be necessary;
`
`the control device already
`
`has peripheral signal
`
`inputs from external sensors as well as a drive
`
`15
`
`line for the safety valve, by way of which the drive may be able to
`
`be undertaken for valve function checkingo.
`The method and monitoring means may thus make possible,
`
`in
`
`advantageous manner,
`
`the constrained monitoring of the valve in engine
`
`operation
`
`(a regular monitoring according to the service intervals
`
`2E)
`
`cannot otherwise be expected, since this is at the discretion of the
`
`vehicle userL the avoidance of undefined influences,
`
`the possible
`
`absence of additional hardware or software, and an increase in the
`
`reliability of the safety system, since the failure probability for
`
`the entire system is reduced by the valve monitoring.
`
`25
`
`Performance of the valve checking within the idling program
`
`course of electronic diesel regulation may be particularly advantageous.
`
`An example of the method and an embodiment of the monitoring means
`
`
`
`of the invention will now be more particularly described with refer-
`
`ence to the accompanying drawing,
`
`the single figure of which is a
`
`schematic block diagram of an electronic diesel regulation system in
`
`association with a quantity setting mechanism.
`
`Referring now to the drawing,
`
`there is shown an embodiment of
`
`monitoring means based on hardware as opposed to software. The
`
`illustration of discrete switching stages does not represent a restrict-
`
`ion, but merely serves to show the basic functional effect of the
`
`monitoring means and to indicate Special functional courses.
`
`It is
`
`10
`
`self-evident that individual components and blocks can be based on
`
`analog, digital or hybrid technique or, combined entirely_or partially,_
`
`can occupy corresponding regions of a program-controlled digital system,
`
`for example a microprocessor, microcomputer, digital or analog logic
`
`circuit and the like,
`
`in which case the operating course of the monitor-
`
`15
`
`ing means can be stored as a program.
`
`The control device of an electronic diesel regulating (EDC) system
`is denoted by 10 and the quantity setting mechanism acted on by the
`
`device 10 is denoted by 11. The device 10 receives indications of
`
`engine rotational speed n from a rotational speed transmitter 12,
`accelerator setting and optionally also clutch pedal setting from an
`
`20
`
`accelerator or clutch pedal setting transmitter 13 as well as, if
`
`desired, brake actuation (brake light) and start information,
`
`together
`
`with signals from further sensors in respect of, for example, constant
`temperature, battery voltage and the like. The device 10 acts by
`way of an end stage 10a on an electromagnetic setting mechanism 14
`
`25
`
`in a fuel
`
`injection pump of the quantity setting mechanism 11, which
`
`also includes a position-reporting device 15.
`
`An electromagnetic
`
`
`
`safety shut-off valve (ELAB), which is associated with the quantity
`
`setting mechanism or the fuel
`
`injection pump,
`
`is denoted by 16 and
`
`is acted on by the device 10 by way of a drive line 16a, for example
`
`as illustrated in the drawing,
`
`through an OR member 17. The member
`
`5
`
`17 receives signals, which derive from a multiplicity of parameters
`
`detected by a safety logic system and lead to switching-off of the
`
`valve, thus blocking of further fuel feed, according to the arrow 18
`
`from a logic circuit within the device 10.
`
`Separately from this,
`
`the drive of the valve 16 takes place through
`
`10
`
`an additional test circuit 19, which is so arranged that the valve is
`
`f
`
`cldSed through appropriate drive in the case of steady idling operation
`
`recognised by appropriate external sensors. This means that the feed
`
`pressure of the fuel reduces and thereby also the injected quantity.
`
`Also provided is an idling regulator circuit, which regulates towards
`
`15
`
`a constant rotational engine speed. This leads to an idling regulator
`
`(not shown} reacting at once to such a reduced injected quantity in
`that it presets a higher target quantity. As long as fuel
`is still
`
`present
`
`in the suction space of the injection pump,
`
`the pump can
`
`supply this higher quantity at higher target regulating travel and
`
`20 thus counteract a drop in engine Speed.
`
`It is therefore possible to recognise a correctly functioning
`
`ELAB valve in steady idling operation at constant rotational
`
`idling
`
`speed through a rise in the idling regulator output magnitude or
`
`the higher regulating travel resulting from this (greater setting
`
`25
`
`angle in the case of a distributor pump)
`
`in the regulating circuit,
`
`since the idling regulator increases the target magnitude in the
`
`setting regulator.
`
`
`
`Such a rise in the idling regulator output magnitude or in the
`
`regulating travel can be correspondingly evaluated as a criterion
`
`for the question of whether or not the valve 16 is able to correctly
`
`function.
`
`A few boundary conditions are associated with the_§LAB test and
`
`are explained in detail
`
`in the following or comprehended by the follow-
`
`ing flow diagram, which illustrates an example of the invention in
`
`the form of a sub—program in a fuel metering program.
`
`1) When steady idling operation is present,
`
`testing of the valve 16
`
`10
`
`is initiated when the following conditions are fulfilled:
`
`1
`
`-
`
`-
`
`-
`
`the start counter has Exceeded a preset-threshold,
`
`:
`
`the injection quantity lies in a range typical for idling,
`
`travel Speed is zero or below a minimum threshold,
`
`the clutch is engaged, i.e. the engine is idling and no gear is
`
`15
`
`engaged, and
`
`-
`
`the accelerator pedal
`
`is disposed in the idling position.
`
`It may also be desirable to interrogate cooling water temperature so
`
`as to ensure that the test is carried out only with the engine hot,
`
`,because in this operational state the idling regulator can best
`
`20
`
`regulate out the disturbance caused by the test.
`2) The functional test of the valve 16 is discontinued when one of the
`afore-named conditions is infringed.
`The functional test is then
`
`initiated anew so often until
`
`the steady idling operation is main—
`
`tained during the entire test duration.
`
`25
`
`During the test,
`
`the idling regulator output magnitude or the
`
`regulating travel
`
`(or setting angle) is checked for the course
`
`which is to be expected with a correctly functioning valve 16.
`
`
`
`If the test is not interrupted for the reason that the steady idling
`
`operation is departed from,
`
`the test can be performed to the end
`
`and, if the preset correct course of the idling regulator output
`
`magnitude (or the regulating travel or setting angle) proving a
`
`correctly functioning valve 76 does not then result, a suitable
`
`warning can be communicated to the driver.
`
`For example,
`
`the driver
`
`can be notified by way of a diagnostic lamp that workshop attention
`
`is needed.
`
`If the test indicates that the valve is functioning correctly the
`
`10
`
`start career
`
`is reset to zero.
`
`11-)
`
`After the test.decision,
`
`the valve 16'is:immediately driven open
`
`again.
`
`It is also opened if a dip in engine speed or an infringe-
`
`ment of the afore-mentioned boundary conditions takes place during
`
`the course of the test.
`
`By this means it is ensured that even
`
`15
`
`abrupt accelerator pedal changes (acceleration steps) are accepted
`
`at once.
`_
`Alternatively, it is possible in place of complete closing of the
`
`valve 16 ELAB to key its operation by an appropriate drive over
`
`time in accordance with a preset function;
`
`thus, for example,
`
`the
`
`20
`
`valve can be opened for 60% of the time and closed for 40% of the
`
`time.
`
`Since-about half of the fuel flowing into the injection pump in
`
`the feed is injected, whilst the other half in normal operation is
`
`conducted through an overflow back to the tank, sufficient quantity
`
`25
`
`is always available even during keyed valve operation in order to
`
`correctly develop the injection processes.
`
`It is merely the overflow
`
`quantity thatis reduced.
`
`
`
`_ 1o _
`
`On the other hand, changes in feed pressure will also lead to
`
`quantity changes, which as a disturbing magnitude are regulated
`
`out
`
`in the idling regulator circuit and therefore in turn lead to
`
`corresponding reactions in the idling regulator output magnitude
`
`(or in the regulating travel or setting angle). These reactions
`
`are evaluated for the checking of the operational function of the
`
`valve 16 in the manner described above.
`
`The following flow diagram shows an example of the ELAB test
`
`realised in a computer as a program course (sub-program).
`
`
`
`_ 11 _
`
`SUB-PROGRAM ELAB TEST
`
` Idle quantity
`operation
`
`
`
`Steady idling
`
`travel speed zero
`
` accelerator
`oedal
`— idle
`
`settm
`
`
`temp t > to
`
`Actuation of
`
`Warning Light
`
`
`
`
` ELAB valve, off 0
`keyed control
`
`
`
`.change in
`.
`1dl1ng regulat1q-
`
`permete
`
` Yes
`ELAB valve OK
`
`
`ELAB valve ooen
`
`
`
`normal quantity regulation
`
`
`
`
`
`_ 12 -
`
`CLAIMS
`
`1.
`
`A method of monitoring the integrity of an electromagnetic safety
`
`valve responsive to a fault condition to cut off fuel feed in a
`
`vehicle internal combustion engine with electronically regulated fuel
`
`5
`
`metering, the method comprising the steps of completely or partially
`
`interrupting fuel feed by way of the valve during steady idling of
`
`the engine in normal vehicle travel operation and evaluating consequent
`
`change in an idling regulation parameter as an indication of correct
`
`functioning of the valve.
`
`10
`
`2." A method as claimed in claim 1, wherein the indication is provided
`
`by rise in an idling regulator output magnitude.
`
`3.
`
`A method as claimed in claim 1, wherein the indication is provided
`
`by an increased travel of a regulating component
`
`in fuel
`
`injection
`
`pump means.
`
`15
`
`4.
`
`A method as claimed in claim 1, wherein the indication is provided
`
`by an increased setting angle of a regulating component
`
`in fuel
`
`distributor pump means.
`
`5.
`
`A method as claimed in any one of the preceding claims, comprising
`
`the steps of recognising steady idling of the engine when the conditions
`
`20
`
`are satisfied that a start counter has exceeded a preset threshold,
`
`the injection quantity lies in a predetermined normal
`
`range for engine
`
`idling,
`
`the vehicle travel speed is equal
`
`to zero or below a minimum
`
`threshold,
`
`the vehicle transmission is in neutral and the vehicle
`
`
`
`-13-
`
`accelerator pedal
`
`is in the idle setting.
`
`6.
`
`A method as claimed in claim 5, comprising the step of recognising
`
`steady idling of the engine when the further condition is satisfied
`
`that water temperature indicates that the engine is warm.
`
`7.
`
`A method as claimed in either claim 5 or claim 6, comprising the
`
`steps of discontinuing fuel
`
`feed interruption by the valve if any one
`
`of the conditions ceases to be satisfied and resuming the fuel feed
`
`interruption when steady idling is again recognised.
`
`8.
`
`A method as claimed in any one of claims 5 to 7, comprising the
`
`steps of resetting the counter to zero and opening the safety valve
`
`after indication of correct functioning of the valve.
`
`9.
`
`A method as claimed in claim 1 and substantially as hereinbefore
`
`described with reference to the accompanying drawing.
`
`10. Monitoring means for monitoring the integrity of an electromagnetic
`
`safety valve responsive to a fault condition to cut off fuel feed in
`
`a vehicle internal combustion engine with electronically regulated
`
`fuel metering,
`
`the monitoring means comprising test circuit means
`
`to detect steady idling of the engine and cause operation of the
`
`valve for complete or partial
`
`interruption of fuel feed during such
`
`steady idling and to evaluate consequent change in an idling regulat—
`
`ion parameter as an indication of correct functioning of the valve.
`
`10
`
`15
`
`20
`
`
`
`‘IF
`
`_ 14 _
`
`11. Monitoring means as claimed in claim 10, wherein the indication
`
`is provided by rise in an idling regulator output magnitude or by
`an increased travel or setting angle of a regulating component
`in
`
`pump means.
`
`5
`
`12. Monitoring means substantially as hereinbefore described with
`
`reference to the accompanying drawing.
`
`”be untamed from ThePatent Dmce
`Published 1990 at The rammomcejmw Housefifi 71 High Halbom.1.onuon WGlEéTP.Pumhe:' copiesm
`59].; 3mm, 3: Mary Cray. Dmmgwn. Kent. 132.5 and E'rmnecl by numplex mommies no. a: Mary Cray. Kenn Con. 1 B7
`
`
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