GB2042074A - Fuel injection apparatus having means to prevent vapour lock - Google Patents

Fuel injection apparatus having means to prevent vapour lock Download PDF

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Publication number
GB2042074A
GB2042074A GB8003144A GB8003144A GB2042074A GB 2042074 A GB2042074 A GB 2042074A GB 8003144 A GB8003144 A GB 8003144A GB 8003144 A GB8003144 A GB 8003144A GB 2042074 A GB2042074 A GB 2042074A
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GB
United Kingdom
Prior art keywords
valve
pressure
chamber
diaphragm
fuel
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Granted
Application number
GB8003144A
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GB2042074B (en
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Audi AG
Original Assignee
Audi NSU Auto Union AG
Audi AG
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Audi NSU Auto Union AG, Audi AG filed Critical Audi NSU Auto Union AG
Publication of GB2042074A publication Critical patent/GB2042074A/en
Application granted granted Critical
Publication of GB2042074B publication Critical patent/GB2042074B/en
Expired legal-status Critical Current

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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
    • F02M69/00—Low-pressure fuel-injection apparatus ; Apparatus with both continuous and intermittent injection; Apparatus injecting different types of fuel
    • F02M69/30—Low-pressure fuel-injection apparatus ; Apparatus with both continuous and intermittent injection; Apparatus injecting different types of fuel characterised by means for facilitating the starting-up or idling of engines or by means for enriching fuel charge, e.g. below operational temperatures or upon high power demand of engines
    • F02M69/36—Low-pressure fuel-injection apparatus ; Apparatus with both continuous and intermittent injection; Apparatus injecting different types of fuel characterised by means for facilitating the starting-up or idling of engines or by means for enriching fuel charge, e.g. below operational temperatures or upon high power demand of engines having an enrichment mechanism modifying fuel flow to injectors, e.g. by acting on the fuel metering device or on the valves throttling fuel passages to injection nozzles or overflow passages
    • F02M69/38—Low-pressure fuel-injection apparatus ; Apparatus with both continuous and intermittent injection; Apparatus injecting different types of fuel characterised by means for facilitating the starting-up or idling of engines or by means for enriching fuel charge, e.g. below operational temperatures or upon high power demand of engines having an enrichment mechanism modifying fuel flow to injectors, e.g. by acting on the fuel metering device or on the valves throttling fuel passages to injection nozzles or overflow passages using fuel pressure, e.g. by varying fuel pressure in the control chambers of the fuel metering device
    • F02M69/386—Low-pressure fuel-injection apparatus ; Apparatus with both continuous and intermittent injection; Apparatus injecting different types of fuel characterised by means for facilitating the starting-up or idling of engines or by means for enriching fuel charge, e.g. below operational temperatures or upon high power demand of engines having an enrichment mechanism modifying fuel flow to injectors, e.g. by acting on the fuel metering device or on the valves throttling fuel passages to injection nozzles or overflow passages using fuel pressure, e.g. by varying fuel pressure in the control chambers of the fuel metering device variably controlling the pressure of the fuel by-passing the metering valves, e.g. by valves responsive to signals of temperature or oxygen sensors
    • 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
    • F02M69/00—Low-pressure fuel-injection apparatus ; Apparatus with both continuous and intermittent injection; Apparatus injecting different types of fuel
    • F02M69/16—Low-pressure fuel-injection apparatus ; Apparatus with both continuous and intermittent injection; Apparatus injecting different types of fuel characterised by means for metering continuous fuel flow to injectors or means for varying fuel pressure upstream of continuously or intermittently operated injectors
    • F02M69/18—Low-pressure fuel-injection apparatus ; Apparatus with both continuous and intermittent injection; Apparatus injecting different types of fuel characterised by means for metering continuous fuel flow to injectors or means for varying fuel pressure upstream of continuously or intermittently operated injectors the means being metering valves throttling fuel passages to injectors or by-pass valves throttling overflow passages, the metering valves being actuated by a device responsive to the engine working parameters, e.g. engine load, speed, temperature or quantity of air
    • F02M69/22—Low-pressure fuel-injection apparatus ; Apparatus with both continuous and intermittent injection; Apparatus injecting different types of fuel characterised by means for metering continuous fuel flow to injectors or means for varying fuel pressure upstream of continuously or intermittently operated injectors the means being metering valves throttling fuel passages to injectors or by-pass valves throttling overflow passages, the metering valves being actuated by a device responsive to the engine working parameters, e.g. engine load, speed, temperature or quantity of air the device comprising a member movably mounted in the air intake conduit and displaced according to the quantity of air admitted to the engine
    • 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
    • F02M69/00—Low-pressure fuel-injection apparatus ; Apparatus with both continuous and intermittent injection; Apparatus injecting different types of fuel
    • F02M69/16—Low-pressure fuel-injection apparatus ; Apparatus with both continuous and intermittent injection; Apparatus injecting different types of fuel characterised by means for metering continuous fuel flow to injectors or means for varying fuel pressure upstream of continuously or intermittently operated injectors
    • F02M69/26—Low-pressure fuel-injection apparatus ; Apparatus with both continuous and intermittent injection; Apparatus injecting different types of fuel characterised by means for metering continuous fuel flow to injectors or means for varying fuel pressure upstream of continuously or intermittently operated injectors the means varying fuel pressure in a fuel by-pass passage, the pressure acting on a throttle valve against the action of metered or throttled fuel pressure for variably throttling fuel flow to injection nozzles, e.g. to keep constant the pressure differential at the metering valve
    • 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
    • F02M69/00—Low-pressure fuel-injection apparatus ; Apparatus with both continuous and intermittent injection; Apparatus injecting different types of fuel
    • F02M69/46—Details, component parts or accessories not provided for in, or of interest apart from, the apparatus covered by groups F02M69/02 - F02M69/44
    • F02M69/54—Arrangement of fuel pressure regulators

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  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Analytical Chemistry (AREA)
  • Fuel-Injection Apparatus (AREA)
  • Supplying Secondary Fuel Or The Like To Fuel, Air Or Fuel-Air Mixtures (AREA)

Abstract

A shut off valve 61 is located in the return passage 58 from the chamber 20 of the differential-pressure regulating valve 17 and is subject to the pressure in the chamber 19, such that some pressure in the chamber 20 is maintained when the engine is shut down. A fuel pump 22 delivers fuel under pressure to the metering valve 6 and to the regulating valve 17, a pressure accumulator 24 being located between the fuel pump and the valves 17, 6. The arrangement deters vapour lock. <IMAGE>

Description

SPECIFICATION Fuel injection apparatus The invention relates to fuel injection apparatus for a mixture-compressing, spark-ignition internal combustion engine with continuous injection, including an induction passage containing an adjustable throttle valve and an airflow sensing device arranged to actuate a fuelmetering valve, fuel metering being effected at a constant pressure difference, which can however be varied in accordance with operating parameters of the engine and which can be regulated by a differential-pressure regulating valve having two chambers, separated by a diaphragm, the first chamber being connected to a return passage via a valve port controlled by the diaphragm, while the second chamber is acted upon by the pressure upstream of the metering valve, and including a fuel pump which delivers fuel under pressure to the metering valve.
In injection apparatus of this type, fuel vapour bubbles can form when the internal combustion engine has been switched off which make re-starting extremely difficult while the internal combustion engine is still warm, unless a certain pressure is maintained in the system at least for a limited period.
An object of the invention is to provide fuel injection apparatus of this type, including means to prevent a rapid reduction in the fuel pressure in the apparatus when the internal combustion engine has been switched off.
Broadly stated the invention consists in fuel injection apparatus of the type specified above, including a pressure accumulator located between the fuel pump and the metering valve, and a shutoff valve located in the return passage from the first chamber, and acted upon in the opening direction by the pressure in the second chamber.
One result of this proposal of the invention is that an appreciable pressure is maintained in the whole system after switching-off. The fact that the shutoff valve is acted upon in the opening direction by the pressure in the second chamber of the differential-pressure regulating valve ensures that it is open during operation, so that no unwanted reaction occurs on the differential pressure. The shutoff valve's opening pressure lies so far below the spray pressure of the injection valve and so far above the accumulator pressure that, after switching off, the injection valve is quickly closed and also emptying of the accumulator is reliably prevented. For example, if the injection valve has a spray pressure of 3.3 bar and the accumulator has a pressure of 2.2 bar the opening pressure of the shutoff valve can be approximately 2.7 bars.
Conveniently the shutoff valve has a valve element which is spring-loaded in the closing direction and is connected to a diaphragm which is subject on one side to the pressure in the second chamber of the differential-pressure regulating valve, acting in a direction to cause the valve element to open. It is particularly advantageous to locate the shutoff valve in the housing of the differential-pressure regulating valve, thereby enabling its diaphragm to be made integral with the diaphragm of the differential-pressure regulating valve. This brings about a considerable structural simplification and gives the advantage that hardly any additional space is needed for the shutoff valve. The shutoff valve's diaphragm can be acted upon on the other side by the pressure in the first chamber of the differential-pressure regulating valve.This has the advantage that it is not necessary to seal the valve shaft connecting the diaphragm to the valve body.
The invention may be performed in various ways and one embodiment will now be described by way of example with reference to the accompanying drawing, which is a somewhat diagrammatic side elevation, partly in section, of a fuel injection system according to the invention.
In the embodiment illustrated, the numeral 1 denotes an air intake passage of a mixturecompressing spark ignition internal combustion engine, including an adjustable throttle valve 2 and a flow sensing device 3, which moves according to the quantity of air flowing in the direction of the arrow. The device 3 is in the form of a baffle plate and is located in or adjacent a conical section 4 of the intake passage 1. The baffle plate 3 is pivotably mounted at 5, and acts upon a movable valve piston 6 of a fuel proportioning or metering valve 7. The valve piston 6 is located in a cylindrical bore 8, in the wall of which a number of control slots 10 are provided, corresponding to the number of injection nozzles 9 as indicated by arrows.Connected to each control slot 10 is a diaphragm valve 11, which has two chambers 1 3 and 14 separated from each other by a diaphragm 1 2. Each chamber 1 3 communicates via a passage 1 5 with the respective control slot 10, and communicates with the respective injection nozzle 9 via a valve aperture 16, which is controlled by the diaphragm 1 2.
A differential pressure regulating valve 1 7 forming part of the fuel injection system, has two chambers 1 9 and 20, separated from each other by a diaphragm 1 8. An electricaily driven fuel pump 22 supplies fuel via a pipe 21 to the chamber 19 at system pressure, which is determined by a system pressure retaining valve 23. A fuel accumulator 24 is located in the pipe 21 immediately downstream of the fuel pump 22. The chamber 1 9 also communicates through a pipe 25 and a passage 26 with an annular groove 27 in the valve piston 6 of the fuel metering valve 7.
The chamber 20 is connected to the chamber 1 9 via a bypass passage 28 with a throttle 29, and is connected by a communicating passage 30 and a spring chamber 31 via a pipe 32 to the second chambers 14 of all the diaphragm valves 11.
Bearing on the face of the diaphragm 18, which forms part of the first chamber 20, are two springs of different spring force. One of the springs 33 bears directly on the diaphragm 18 with a relatively large spring force' of approximately 6.6 kp. The second spring 34 serves as a contact spring of smaller spring force (approximately 0.5 kp) and its lower ends bears against the diaphragm 1 8 via a valve body 36 which passes through the first chamber 20 and is movable in a bore 35, a plastic contact plate 36a being located between the valve body 36 and the diaphragm 1 8 to reduce wear. On the other side of the contact spring 34 is located a device comprising a diaphragm box 37 which reacts to the instantaneous load condition of the engine.
The diaphragm box 37 includes a diaphragm 39 which defines a low pressure chamber 42 and is engaged by a compression spring 38, and co-operates with the spring 34 via a setting screw 40 and an adjusting pin 41 which is movable in the housing of the diaphragm box 37. The low pressure chamber 42 is connected via a pipe 43 to the intake passage 1, downstream of the throttle valve 2.
Against the other side of the diaphragm 1 8 which faces the second chamber 19, bears a spring 44 having a spring force of approximately 0.9 kp. This spring butts against a device for cold starting enrichment, via an adjusting pin 45 which passes through the second chamber 1 9. The device for cold starting enrichment comprises a thermo-couple 46, which is mounted in a threaded bushing 49, movable in a housing, by means of a flanged ring 47. Attached to the thermocouple 46 is an additional heating element 50 such as, for example, a PTC element supplied with electric heater current via a contact 51.
The flanged ring 47 is arranged to be movable against the spring force of a compression spring 52, inside the threaded bushing 49, so that the thermo-couple can expand downwards when heated. An adjustable spring plate 53 is located on a thread on the adjusting pin 45 located between the thermocouple 46 and the spring 44 and when the thermocouple 46 is moved, the spring plate is pressed approximately 4.5 mm upwards and is brought into contact with the wall defining the chamber 1 9. In this position, the spring 44 also generates a spring force of approximately 4.6 kp, the differential pressure being set at approximately 0.18-0.45 bars. As a result of the arrangement and action of the springs 33 and 34 on the one hand, and the springs 44 and 54 on the other hand, the valve body 36 is almost entirely relieved of spring resistance which might impair its movability.The differential pressure valve, together with the device 37 reacting to the load condition of the engine, and the device 48, 50 for cold starting enrichment, form a compact structural unit.
The pressure in the first chamber 20, which determines the differential pressure at the proportioning valve 7, is controlled by the device reacting to the load condition of the engine and by the device for cold starting enrichment, which act on opposite sides against the diaphragm 1 8 and open the flow cross-section through the valve body 36 to a greater or lesser extent and thus vary the difference in pressure between the chambers 1 9 and 20. To this end, the valve body 36 is formed with a passage 55 connected to the chamber 20, and also to a control aperture 56, which co-operates with an outlet port 57 located in the wall of the bore 35. The outlet port being connected by a return passage to a.
return pipe 60 which discharges into the fuel tank 59. By means of the setting screw 40 and the adjustable spring plate 53, the spring tolerances and spring rates can be compensated and the tension of the several springs be adjusted in such a way that the desired level of differential pressure is obtained in the proportioning valve.
In the return passage 58 is located a stop valve 61, which includes a valve body 62 pressed by a spring 63 tightly against a valve seat 64 in the normal position of rest. A valve stem 65 connected to the valve body 62 is attached to a diaphragm 66 which defines a lower chamber 67 which is subject to the system pressure via the pipe 21, and also defines an upper chamber 68 connected to the return passage 58. Under running conditions the system pressure acts against the diaphragm 66, so that the stop valve 61 is opened and the return pipe is relieved.
Through the stop valve 61, the pressure in the differential pressure regulating valve 1 7 is also maintained for a considerable time after the engine is switched off, so that vapour bubbles do not form. As a result, the fuel injection system with the differential pressure regulating valve 1 7 is always ready for operation.
As can be seen, the stop valve 61 is integrated in the housing of the differential pressure regulating valve 17, and its diaphragm 66 forms part of the diaphragm 18 of the differential pressure regulating valve.
Hence little or no extra space is required for the stop valve.
Fuel delivered by the fuel pump 22 passes through the pipe 21 not only into the second chamber 1 9 of the differential pressure regulating valve 17, but also through a pipe 25 and passage 26 into the annular groove 27 of the valve piston 6. The valve piston 6 is moved upwards out of its rest position by the baffle plate 3, according to its deflection by the quantity of air flowing through the inlet passage 1. This is opposed by a counter-force produced by a spring 69 in the illustrated example, such that its control edge 70 opens the control slots 10 to a greater or lesser extent, in proportion to the deflection of the baffle plate 3.Fuel therefore passes through the passages 1 5 in the first chambers 1 3 of the diaphragm valves 11, and thence through the valve ports 1 6 to the respective injection nozzles 9.
To ensure that the quantity of fuel supplied to the injection nozzles 9 is appropriate to the particular instantaneous running condition of the engine, the level of the differential pressure is determined via the diaphragm box 37 and via the thermo-couple 46 in dependence upon the load condition and the running temperature of the engine, which vary the prestress of the springs 33 and 34 and also springs 44 and 54 acting upon the diaphragm 1 8. If the throttle valve 2 is opened from the position shown, for example, a reduction of the suction effect in the low pressure chamber 42 occurs, so that the compression spring 38, via the spring 34, presses more strongly against the valve body 36 and actuates the latter in an opening direction, to cause fuel enrichment. Fuel enrichment during warming up of the engine after a cold start is obtained by the fact that the pin 46a of the thermocouple 46 is retracted as shown, and the initial force of the spring 44 therefore reduced. Thus the valve body 36 is also actuated in an opening direction. Depending upon the operating engine conditions, intermediate positions are naturally produced under the influence of the two operating parameters, so as to provide appropriate fuel metering.

Claims (5)

1. Fuel injection apparatus for a mixturecompressing, spark-ignition internal combustion engine with continuous injection, including an induction passage containing an adjustable throttle valve and an air flow sensing device arranged to actuate a fuel-metering valve, fuel metering being effected at a constant pressure difference, which can however be varied in accordance with operating parameters of the engine and which can be regulated by a differential-pressure regulating valve having two chambers, separated by a diaphragm, the first chamber being connected to a return passage via a valve port controlled by the diaphragm, while the second chamber is acted upon by the pressure upstream of the metering valve, and including a fuel pump which delivers fuel under pressure to the metering valve, and a pressure accumulator located between the fuel pump and the metering valve, and a shutoff valve located in the return passage from the first chamber, and acted upon in the opening direction by the pressure in the second chamber.
2. Fuel injection apparatus according to Claim 1, in which the shut off valve has a valve element which is spring-loaded in the closing direction and is connected to a diaphragm which is subject on one side to the pressure in the second chamber of the differential-pressure regulating valve, acting in a direction to cause the valve element to open.
3. Fuel injection apparatus according to Claim 2, in which the diaphragm is subject on the other side to the pressure in the first chamber of the differential-pressure regulating valve.
4. Fuel injection apparatus according to Claims 1 and 2, in which the shut off valve is located in the housing of the differentialpressure regulating valve and its diaphragm is integral with the diaphragm of the differentialpressure regulating valve.
5. Fuel injection apparatus for a mixturecompressing, spark-ignition internal combustion engine with continuous injection, substantially as described with reference to the accompanying drawings.
GB8003144A 1979-02-09 1980-01-30 Fuel injection apparatus having means to prevent vapour lock Expired GB2042074B (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
DE19792904910 DE2904910A1 (en) 1979-02-09 1979-02-09 FUEL INJECTION SYSTEM

Publications (2)

Publication Number Publication Date
GB2042074A true GB2042074A (en) 1980-09-17
GB2042074B GB2042074B (en) 1982-11-24

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ID=6062540

Family Applications (1)

Application Number Title Priority Date Filing Date
GB8003144A Expired GB2042074B (en) 1979-02-09 1980-01-30 Fuel injection apparatus having means to prevent vapour lock

Country Status (5)

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JP (1) JPS55107063A (en)
DE (1) DE2904910A1 (en)
FR (1) FR2448630A1 (en)
GB (1) GB2042074B (en)
SE (1) SE8000858L (en)

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4530329A (en) * 1982-12-28 1985-07-23 Robert Bosch Gmbh Fuel injection system
WO1988001347A1 (en) * 1986-08-13 1988-02-25 Ashland Oil, Inc. Process and apparatus for reducing port fuel injector deposit
WO2009049999A1 (en) * 2007-10-12 2009-04-23 Robert Bosch Gmbh Fuel supply system and relief valve for a fuel supply system

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4774923A (en) * 1986-11-07 1988-10-04 Aisan Kogyo Kabushiki Kaisha Pressure regulating valve

Family Cites Families (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3974809A (en) * 1973-03-16 1976-08-17 Robert Bosch G.M.B.H. Fuel injection system for spark plug-ignited internal combustion engines with compression of the air-fuel mixture

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4530329A (en) * 1982-12-28 1985-07-23 Robert Bosch Gmbh Fuel injection system
WO1988001347A1 (en) * 1986-08-13 1988-02-25 Ashland Oil, Inc. Process and apparatus for reducing port fuel injector deposit
US4782808A (en) * 1986-08-13 1988-11-08 Ashland Oil, Inc. Process and apparatus for reducing port fuel injector deposits
WO2009049999A1 (en) * 2007-10-12 2009-04-23 Robert Bosch Gmbh Fuel supply system and relief valve for a fuel supply system

Also Published As

Publication number Publication date
GB2042074B (en) 1982-11-24
JPS55107063A (en) 1980-08-16
FR2448630A1 (en) 1980-09-05
DE2904910A1 (en) 1980-08-14
SE8000858L (en) 1980-08-10

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PCNP Patent ceased through non-payment of renewal fee