EP0206485B1 - Fuel supply control method for internal combustion engines at start - Google Patents
Fuel supply control method for internal combustion engines at start Download PDFInfo
- Publication number
- EP0206485B1 EP0206485B1 EP86303498A EP86303498A EP0206485B1 EP 0206485 B1 EP0206485 B1 EP 0206485B1 EP 86303498 A EP86303498 A EP 86303498A EP 86303498 A EP86303498 A EP 86303498A EP 0206485 B1 EP0206485 B1 EP 0206485B1
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- EP
- European Patent Office
- Prior art keywords
- fuel
- pressure
- fuel injection
- engine
- supply voltage
- Prior art date
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
- F02D—CONTROLLING COMBUSTION ENGINES
- F02D41/00—Electrical control of supply of combustible mixture or its constituents
- F02D41/02—Circuit arrangements for generating control signals
- F02D41/04—Introducing corrections for particular operating conditions
- F02D41/06—Introducing corrections for particular operating conditions for engine starting or warming up
- F02D41/062—Introducing corrections for particular operating conditions for engine starting or warming up for starting
Definitions
- This invention relates to a fuel supply control method for internal combustion engines at start.
- a conventional fuel supply control method has been proposed, e.g. by Japanese Provisional Patent Publication (Kokai) No. 57-137633, wherein when the engine is in a starting condition, a valve opening period TOUT for the fuel injection valves is set to a value obtained by adding to or deducting from a basic valve opening period TiCR set, e.g., based upon engine temperature in a manner decreasing with an increase in the engine temperature, a correction value TV dependent on supply voltage supplied from an electric power source such as battery and a generator to the fuel injection valves to drive same, and the fuel injection values are controlled to open over a period of time according to the thus set valve opening period TOUT.
- a valve opening period TOUT for the fuel injection valves is set to a value obtained by adding to or deducting from a basic valve opening period TiCR set, e.g., based upon engine temperature in a manner decreasing with an increase in the engine temperature, a correction value TV dependent on supply voltage supplied from an electric power source such as battery and a generator
- the correction value TV according to the proposed method is employed for compensation for a delay in the response of the fuel injection valves due to low supply voltage supplied thereto from the electric power source, e.g. during starting of the engine.
- US-A-4445483 describes a method of controlling fuel supply to an internal combustion engine at start, said engine having at least one fuel injection valve, a feed pump for pressurizing fuel and supplying pressurized fuel to said fuel injection valve, fuel pressure regulating means supplied with pressure within the intake passage of said engine prevailing in the vicinity of said fuel injection valve for supplying said fuel injection valve with fuel at such a pressure that the difference between the pressure of fuel supplied to said fuel injection valve and said pressure within said intake passage is regulated to a predetermined constant value irrespective of change in said pressure within said intake passage when the pressure of fuel pressurized by said feed pump and supplied therefrom to said fuel pressure regulating means is higher than a predetermined value, and a battery for driving said fuel injection valve, said fuel injection valve being adapted to be opened over a valve opening period of time set at least based upon a temperature of said engine and corrected by adding a correction variable for compensating for a delay in the response of said fuel injection valve due to detected low supply voltage supplied thereto from said battery so as to supply a required quantity of fuel
- the present invention provides a method for controlling fuel supply to an internal combustion engine at start, the engine having at least one fuel injection valve, a feed pump for pressurizing fuel and supplying pressurized fuel to the fuel injection valve, fuel pressure regulating means supplied with pressure within the intake passage of said engine prevailing in the vicinity of said fuel injection valve for supplying said fuel injection valve with fuel at such a pressure that the difference between the pressure of fuel supplied to said fuel injection valve and said pressure within said intake passage is regulated to a predetermined constant value irrespective of change in said pressure within said intake passage when the pressure of fuel pressurized by said feed pump and supplied therefrom to said fuel pressure regulating means is higher than a predetermined value, and a battery for driving the fuel injection valve and the feed pump, the fuel injection valve being adapted to be opened over a valve opening period of time set at least based upon a temperature of the engine and corrected by adding a correction variable for compensating for a delay in the response to the fuel injection valve due to low supply voltage supplied thereto from said battery so as to supply a required quantity of fuel to
- the method according to the invention is characterized by comprising the following steps: (1) detecting a value of the supply voltage from said battery is a parameter indicative of the pressure of fuel pressurized by the feed pump to be supplied to the fuel injection valve; (2) determining a correction value corresponding only to the parameter value thus detected, the correction value being set to increase the valve opening period with decrease in the pressure of fuel pressurized by the feed pump; and (3) correcting the valve opening period of time by multiplying by the correction value thus determined.
- the correct value is set to increase the valve opening period with decrease in the supply voltage insofar as the supply voltage is lower than a predetermined value corresponding to the predetermined value of the pressure of fuel pressurized by the feed pump.
- the fuel injection quantity Qf per injection of the fuel injection values varies as a function of the pressure difference AP (hereinafter referred to as "the fuel pressure difference" unless otherwise specified) between the fuel pressure supplied to the fuel injection valves from the fuel tank through fuel pressurizing means such as a feed pump, and the internal pressure within the intake passage of the engine prevailing in the vicinity of the fuel injection valves, and also as a function of the valve opening period value TOUT, and can be expressed as follows:
- the valve opening period value TOUT for the fuel injection valves is set on the presumption that the fuel pressure difference AP remains constant and assumes a certain value, and accocdingly, the set value TOUT does not correspond to fluctuations in the fuel pressure difference AP. However, under certain operating conditions of the engine, the fuel pressure difference AP does not assume the certain value.
- the fuel pressure supplied from the feed pump to the fuel injection valves is low and accordingly the fuel pressure difference AP is small, resulting in an insufficient fuel injection quantity Qf per injection of the fuel injection valves even if they are opened over a period of time according to the set valve opening period TOUT, which can deteriorate the startability and driveability of the engine.
- the invention is capable of supplying a required quantity of fuel to the engine at start thereof even when the fuel pressure supplied to fuel injection valves of the engine from feed pump is so low due to low supply voltage from an electric power source at the start of the engine that the fuel pressure difference between the supplied fuel pressure and the internal pressure within the intake passage in the vicinity of the fuel injection valves is smaller than a predetermined constant value, to thereby improve the startability and driveability of the engine at start.
- FIG. 1 there is illustrated the whole arrangement of a fuel supply control system to which is applied the method according to the invention.
- Reference numeral 1 denotes an internal combustion engine of a four-cylinder type for instance, only one cylinder being shown, to which is connected one end of an intake pipe 3, the other end of which communicates with the atmosphere via an air cleaner 4.
- a throttle valve 5 is arranged in the intake pipe 3, and a throttle valve opening (6th) sensor 6 is connected to the throttle valve 5 for detecting its opening and supplying an electrical signal indicative of the detected throttle valve opening to an electronic control unit (hereinafter called "the ECU") 7.
- the ECU electronice control unit
- An absolute pressure (PBA) sensor 9 communicates through a conduit 8 with the interior of the intake pipe 3 at a location downstream of the throttle valve 5, and an electrical output signal indicative of the detected absolute pressure is supplied to the ECU 7. Further, an intake air temperature (TA) sensor 10 projects into the interior of the intake pipe 3 at a location downstream of the conduit 8, for supplying the ECU 7 with an electrical signal indicative of the detected intake air temperature.
- PBA absolute pressure
- TA intake air temperature
- An engine cooling water temperature (TW) sensor 11 is mounted on the main body of the engine 1 in a manner embedded in the peripheral wall of an engine cylinder, for applying an electrical output signal indicative of the detected water temperature TW as representative of the engine temperature to the ECU 7.
- a starter (starting motor) 12 is provided for the engine 1 for driving the engine during cranking.
- the input side of the starter 12 is connected to a terminal 13a of a key switch 13.
- the key switch 13 has a further terminal 13b connected to a feed pump 14 as well as to fuel injection valves 19, hereinafter referred to, and another terminal 13c connected to an electric power supply source 15 such as a generator and a battery.
- the terminal 13a of the key switch 13 is connected to the ECU 7 to supply same with an electrical signal indicative of on and off states of the starter 12.
- the terminal 13b is connected to the ECU 7 to supply same with an electrical signal indicative of supply voltage VB to be supplied from the power supply source 15 to the feed pump 14 as well as to the fuel injection valves 19.
- Referrence numeral 16 denotes an engine rotational speed (Ne) sensor arranged in face-to-face relation to, e.g., a camshaft, not shown, of the engine for supplying the ECU 7 with an electrical signal indicative of predetermined crank angles detected thereby.
- Ne engine rotational speed
- sensors 17 Further electrically connected to the ECU 7 are other sensors 17 such as an atmospheric pressure (PA) sensor and an exhaust 0 2 sensor to supply the ECU with respective electrical signals indicative of detected parameter values.
- PA atmospheric pressure
- Fuel injection valves 19 are arranged in the intake pipe 3 each at a location slightly upstream of an intake valve 18 of a corresponding one of the engine cylinders, and connected with a fuel tank 22 through a conduit 20, a fuel filter 21, and the feed pump 14 to be supplied with fuel pressurized by the feed pump 14.
- Reference numeral 23 denotes a pressure regulating valve, a casing of which has its interior divided by a diaphragm 23b into a vacuum chamber 23c and a fuel chamber 23d.
- the vacuum chamber 23c communicates through a vacuum passage 24 with the interior of the intake pipe 3 at a location downstream of the throttle valve 5, so as to be supplied with a vacuum or negative pressure developed in the intake pipe 3 at a zone downstream of the throttle valve 5, i.e. a negative pressure prevailing in the vicinity of the fuel injection valves 19, through the vacuum passage 24.
- the fuel chamber 23d communicates through a conduit 26 with the interior of the conduit 20 extending between the fuel tank 22 and the fuel injection valves 19, at a location between the fuel filter 21 and the fuel injection valves 19, whereby the pressure of fuel being supplied to the fuel injection valves 19 is introduced into the fuel chamber 23d.
- a valve body 23a of the pressure regulating valve 23 is secured to the diaphragm 23b at its substantially central portion and urged via the diaphragm 23b by a spring 23e in a valve closing direction.
- the valve body 23a is seated against a valve seat 23f formed at an open end of a conduit 25 communicating with the fuel tank 22, by the force of the spring 23e urging the valve body 23a via the diaphragm 23b, to close the open end, thereby rendering the pressure regulating valve 23 inoperative. Therefore, so long as the supply voltage VB of the power supply source 15 is lower than the predetermined value, the fuel pressure within the conduit 20, i.e. the pressure of fuel being supplied to the fuel injection valves 19 varies with changes in the supply voltage VB supplied from the power supply source 15 to the feed pump 14.
- the resulting increased fuel supply pressure to the fuel injection valves 19, i.e. increased fuel pressure within the conduit 20, is introduced to the fuel chamber 23d through the conduit 26, to displace the valve body 23a away from the valve seat 23f against the urging force of the spring 23e.
- the valve seat 23f has its opening area increased to thereby increase the amount of fuel returned to the fuel tank 22 through the valve 23.
- the pressure regulating valve 23 operates to maintain constant the fuel pressure difference between the fuel pressure supplied to the fuel injection valves from the fuel tank and the internal pressure within the intake passage of the engine prevailing in the vicinity of the fuel injection valves.
- Each of the fuel injection valves 19, formed of an on-off type solenoid valve, has its solenoid, not shown, connected to the ECU 7 so that when energized by a driving signal from the ECU 7, it opens with its valve body, not shown, lifted through a constant stroke and for a period of time corresponding to the duration of the driving signal, as hereinafter referred to.
- the engine is supplied with an amount of fuel corresponding to the time period for which the driving signal is applied to the fuel injection valves 19 from the ECU 7, i.e. the duration of the driving signals (the valve opening period).
- the engine is supplied with a correspondingly decreased amount of fuel so long as the valve opening period remains constant.
- the ECU 7 comprises an input circuit 7a having functions of shaping waveforms of pulses of input signals from the aforementioned sensors indicative of various operating parameters of the engine 1, shifting voltage levels of the input signals, and converting analog values of the input signals into digital signals, etc., a central processing unit (hereinafter called “the CPU") 7b, memory means 7c for storing various calculation programs to be executed within the CPU 7b, calculated data from the CPU 7b, and calculation data such as a TiCR-TW table, KNe-Ne table, and KPV-VB table, all hereinafter described, and an output circuit 7d for supplying driving signals to the fuel injection valves 19.
- the CPU central processing unit
- memory means 7c for storing various calculation programs to be executed within the CPU 7b, calculated data from the CPU 7b, and calculation data such as a TiCR-TW table, KNe-Ne table, and KPV-VB table, all hereinafter described
- an output circuit 7d for supplying driving signals to the fuel injection valves 19.
- the fuel supply control system constructed as above operates as follows:
- the ECU 7 determines operating conditions of the engine such as a starting condition on the basis of output signals from the various sensors indicative .of engine operating parameters such as engine coolant temperature TW, supply voltage VB, and on and off states of the starter 12, and calculates the valve opening period TOUT for the fuel injection valves 19 in accordance with the determined operating conditions of the engine 1.
- the ECU 7 calculates the valve opening period TOUT by the use of the following equation (1):
- TiCR represents a basic value of the valve opening period TOUT which is applied at the start of the engine, and determined, e.g. based upon the engine coolant temperature TW detected by the TW sensor 11.
- the basic valve opening period value TiCR is read from a TiCR-TW table shown in Fig. 2, for example.
- predetermined values TCR1-TCR5 as the basic valve opening period value are stored and correspond, respectively, to predetermined values TWCR1-TWCR5 of the engine coolant temperature TW, which are set to larger values as the engine coolant temperature TW decreases.
- the basic valve opening period value TiCR is calculated by an interpolation method.
- KPV represents a supply voltage-dependent correction coefficient according to the invention which is determined in dependence on the supply voltage VB to be supplied from the power source 15 to the feed pump 14, e.g., by reading a value of the coefficient KPV corresponding to the supply voltage VB from a KPV-VB table shown in Fig. 5, hereinafter described.
- KNe represents an engine rotational speed-dependent correction coefficient applicable at the start of the engine, which is determined in dependence on the engine rotational speed Ne detected by the Ne sensor 16.
- the coefficient KNe is read from a KNe-Ne table shown in Fig. 3 showing an example of the relationship between the correction coefficient KNe and the engine rotational speed Ne.
- the value of the correction coefficient KNe is calculated by an interpolation method.
- TV represents a supply voltage-dependent correction variable for increasing and decreasing the basic valve opening period value TiCR in response to changes in the supply voltage VB supplied from the power source 15 to the fuel injection valves 19 to drive same, the value of which is, for example, read from a TV-VB table shown in Fig. 4, in response to the supply voltage VB.
- the correction variable TV is set to smaller values as the supply voltage VB increases. For example, when the supply voltage VB is 8,13, and 16 volts, the correction variable TV is set to 1.75, 0.9, and 0.3 ms, respectively.
- the supply voltage-dependent correction variable TV is employed to compensate for a delay in the response of the fuel injection valves 19 due to low supply voltage VB supplied from the power source 15 to the valves 19.
- the correction variable TV By employing the correction variable TV, the actual valve opening time period of the fuel injection valves 19 can be made equal to the first term (TiCRxKNexKPV) at the right side of the equation (1) which is obtained when the supply voltage VB has a normal value.
- the supply voltage-dependent correction coefficient KPV is employed to compensate for a shortage of the fuel injection quantity Of due to a small fuel pressure difference AP caused by a change in the supply voltage VB supplied from the power supply source 15 to the feed pump 14 at the start of the engine, by increasing the valve opening period of the fuel injection valves 19.
- the supply voltage-dependent correction variable TV and the supply voltage-dependent correction coefficient KPV the fuel injection quantity Of per injection of the fuel injection valves 19 can be controlled to a value required at the start of the engine.
- Fig. 5 shows a KPV-VB table showing an example of the relationship between the supply voltage-dependent correction coefficient KPV and the supply voltage VB.
- KPV1 e.g. 1.2
- KPV2 e.g. 1.15
- KPV3 e.g. 1.07
- KPV4 e.g. 1.0
- VBP1 e.g. 6v
- VBP2 e.g. 7v
- VBP3 e.g.
- VBP4 e.g 9v
- the coefficient KPV is set to smaller values with increase in the supply voltage VB so long as the value of the supply voltage VB is lower than the predetermined value VBP4.
- the value of the correction coefficient KPV is calculated by interpolation.
- the value of the correction coefficient KPV is held at 1.0, since the fuel pressure difference AP can be maintained at a constant value by the operation of the pressure regulating valve 23 which operates to maintain constant the fuel supply pressure to the fuel injection valves 19 through the conduit 20.
- the set value of the correction coefficient KPV is applied to the equation (1) whereby the basic valve opening period value TiCR is multiplied by the correction coefficient KPV, thus making it possible to obtain a valve opening period TOUT value appropriate for supplying a required quantity of fuel to the engine at start.
- the ECU 7 supplies the fuel injection valves 19 with driving signals corresponding to the thus calculated valve opening period TOUT, to open same over the time period TOUT.
- the basic valve opening period TiCR is set based upon the engine coolant temperature TW, this is not limitative, but the basic valve opening period may be set based upon the engine coolant temperature TW, and one or more operating parameters of the engine such as the engine rotational speed Ne, intake air quantity, and intake pipe absolute pressure PBA, to be corrected by means of the supply voltage-dependent correction coefficient KPV of the invention.
- the parameter value VB indicative of the pressure of fuel supplied to the fuel injection valves 19 is detected, the correction value KPV corresponding to the detected parameter value VB is determined, and the basic valve opening period TiCR set at least based upon the engine temperature TW is corrected by means of the thus determined correction value KPV. Therefore, it is possible to supply a required quantity of fuel to the engine at start even when the fuel pressure difference AP is small between the fuel pressure supplied to the fuel injection valves 19 and the intake passage pressure in the vicinity of the fuel injection valves 19, which is caused by low supply voltage VB supplied from the fuel supplying means 14, to thereby improve the startability and driveability of the engine.
Description
- This invention relates to a fuel supply control method for internal combustion engines at start.
- A conventional fuel supply control method has been proposed, e.g. by Japanese Provisional Patent Publication (Kokai) No. 57-137633, wherein when the engine is in a starting condition, a valve opening period TOUT for the fuel injection valves is set to a value obtained by adding to or deducting from a basic valve opening period TiCR set, e.g., based upon engine temperature in a manner decreasing with an increase in the engine temperature, a correction value TV dependent on supply voltage supplied from an electric power source such as battery and a generator to the fuel injection valves to drive same, and the fuel injection values are controlled to open over a period of time according to the thus set valve opening period TOUT.
- The correction value TV according to the proposed method is employed for compensation for a delay in the response of the fuel injection valves due to low supply voltage supplied thereto from the electric power source, e.g. during starting of the engine.
- US-A-4445483 describes a method of controlling fuel supply to an internal combustion engine at start, said engine having at least one fuel injection valve, a feed pump for pressurizing fuel and supplying pressurized fuel to said fuel injection valve, fuel pressure regulating means supplied with pressure within the intake passage of said engine prevailing in the vicinity of said fuel injection valve for supplying said fuel injection valve with fuel at such a pressure that the difference between the pressure of fuel supplied to said fuel injection valve and said pressure within said intake passage is regulated to a predetermined constant value irrespective of change in said pressure within said intake passage when the pressure of fuel pressurized by said feed pump and supplied therefrom to said fuel pressure regulating means is higher than a predetermined value, and a battery for driving said fuel injection valve, said fuel injection valve being adapted to be opened over a valve opening period of time set at least based upon a temperature of said engine and corrected by adding a correction variable for compensating for a delay in the response of said fuel injection valve due to detected low supply voltage supplied thereto from said battery so as to supply a required quantity of fuel to said engine at start thereof. EP-53464 discloses detecting a pressure difference valve across a fuel injection valve, and using this valve to correct a fuel injection quantity.
- However, we have found that even with such compensation the startability and drivability of the engine may not be as good as desired.
- It is the object of the invention to provide a fuel supply control method for internal combustion engines at start, which is capable of improving the startability and drivability of the engine at start.
- The present invention provides a method for controlling fuel supply to an internal combustion engine at start, the engine having at least one fuel injection valve, a feed pump for pressurizing fuel and supplying pressurized fuel to the fuel injection valve, fuel pressure regulating means supplied with pressure within the intake passage of said engine prevailing in the vicinity of said fuel injection valve for supplying said fuel injection valve with fuel at such a pressure that the difference between the pressure of fuel supplied to said fuel injection valve and said pressure within said intake passage is regulated to a predetermined constant value irrespective of change in said pressure within said intake passage when the pressure of fuel pressurized by said feed pump and supplied therefrom to said fuel pressure regulating means is higher than a predetermined value, and a battery for driving the fuel injection valve and the feed pump, the fuel injection valve being adapted to be opened over a valve opening period of time set at least based upon a temperature of the engine and corrected by adding a correction variable for compensating for a delay in the response to the fuel injection valve due to low supply voltage supplied thereto from said battery so as to supply a required quantity of fuel to the engine at start thereof.
- The method according to the invention is characterized by comprising the following steps: (1) detecting a value of the supply voltage from said battery is a parameter indicative of the pressure of fuel pressurized by the feed pump to be supplied to the fuel injection valve; (2) determining a correction value corresponding only to the parameter value thus detected, the correction value being set to increase the valve opening period with decrease in the pressure of fuel pressurized by the feed pump; and (3) correcting the valve opening period of time by multiplying by the correction value thus determined.
- Preferably, the correct value is set to increase the valve opening period with decrease in the supply voltage insofar as the supply voltage is lower than a predetermined value corresponding to the predetermined value of the pressure of fuel pressurized by the feed pump.
- The fuel injection quantity Qf per injection of the fuel injection values varies as a function of the pressure difference AP (hereinafter referred to as "the fuel pressure difference" unless otherwise specified) between the fuel pressure supplied to the fuel injection valves from the fuel tank through fuel pressurizing means such as a feed pump, and the internal pressure within the intake passage of the engine prevailing in the vicinity of the fuel injection valves, and also as a function of the valve opening period value TOUT, and can be expressed as follows:
- In the abovementioned known method, the valve opening period value TOUT for the fuel injection valves is set on the presumption that the fuel pressure difference AP remains constant and assumes a certain value, and accocdingly, the set value TOUT does not correspond to fluctuations in the fuel pressure difference AP. However, under certain operating conditions of the engine, the fuel pressure difference AP does not assume the certain value. For instance, when the starting motor has just been actuated to drive the engine, and the rotational speed of the engine is not yet increased to a value high enough to make either the battery or the generator supply a predetermined supply voltage to the feed pump, the fuel pressure supplied from the feed pump to the fuel injection valves is low and accordingly the fuel pressure difference AP is small, resulting in an insufficient fuel injection quantity Qf per injection of the fuel injection valves even if they are opened over a period of time according to the set valve opening period TOUT, which can deteriorate the startability and driveability of the engine.
- The invention is capable of supplying a required quantity of fuel to the engine at start thereof even when the fuel pressure supplied to fuel injection valves of the engine from feed pump is so low due to low supply voltage from an electric power source at the start of the engine that the fuel pressure difference between the supplied fuel pressure and the internal pressure within the intake passage in the vicinity of the fuel injection valves is smaller than a predetermined constant value, to thereby improve the startability and driveability of the engine at start.
- The above and other objects, features and advantages of the invention will be more apparent from the ensuing detailed description of an example of the invention taken in conjunction with the accompanying drawings.
-
- Fig. 1 is a view schematically illustrating the whole arrangement of a fuel supply control system for an internal combustion engine, to which the method according to the invention is applied;
- Fig. 2 is a graph of a table showing an example of the relationship between a basic valve opening period TiCR for fuel injection valves applicable at the start of the engine and engine coolant temperature TW;
- Fig. 3 is a graph of a table showing an example of the relationship between an engine rotational speed-dependent correction coefficient KNe applicable at the start of the engine and the engine rotational speed Ne;
- Fig. 4 is a graph of a table showing an example of the relationship between a supply voltage-dependent correction variable TV and power source supply voltage VB; and
- Fig. 5 is a graph of a table showing an example of the relationship between a supply voltage-dependent correction coefficient KPV according to the invention and the power source supply voltage VB.
- Referring first to Fig. 1, there is illustrated the whole arrangement of a fuel supply control system to which is applied the method according to the invention.
Reference numeral 1 denotes an internal combustion engine of a four-cylinder type for instance, only one cylinder being shown, to which is connected one end of anintake pipe 3, the other end of which communicates with the atmosphere via anair cleaner 4. Athrottle valve 5 is arranged in theintake pipe 3, and a throttle valve opening (6th)sensor 6 is connected to thethrottle valve 5 for detecting its opening and supplying an electrical signal indicative of the detected throttle valve opening to an electronic control unit (hereinafter called "the ECU") 7. - An absolute pressure (PBA)
sensor 9 communicates through aconduit 8 with the interior of theintake pipe 3 at a location downstream of thethrottle valve 5, and an electrical output signal indicative of the detected absolute pressure is supplied to theECU 7. Further, an intake air temperature (TA)sensor 10 projects into the interior of theintake pipe 3 at a location downstream of theconduit 8, for supplying theECU 7 with an electrical signal indicative of the detected intake air temperature. - An engine cooling water temperature (TW) sensor 11 is mounted on the main body of the
engine 1 in a manner embedded in the peripheral wall of an engine cylinder, for applying an electrical output signal indicative of the detected water temperature TW as representative of the engine temperature to theECU 7. - A starter (starting motor) 12 is provided for the
engine 1 for driving the engine during cranking. The input side of thestarter 12 is connected to a terminal 13a of akey switch 13. Thekey switch 13 has afurther terminal 13b connected to afeed pump 14 as well as tofuel injection valves 19, hereinafter referred to, and anotherterminal 13c connected to an electricpower supply source 15 such as a generator and a battery. The terminal 13a of thekey switch 13 is connected to theECU 7 to supply same with an electrical signal indicative of on and off states of thestarter 12. On the other hand, theterminal 13b is connected to theECU 7 to supply same with an electrical signal indicative of supply voltage VB to be supplied from thepower supply source 15 to thefeed pump 14 as well as to thefuel injection valves 19. -
Referrence numeral 16 denotes an engine rotational speed (Ne) sensor arranged in face-to-face relation to, e.g., a camshaft, not shown, of the engine for supplying theECU 7 with an electrical signal indicative of predetermined crank angles detected thereby. - Further electrically connected to the
ECU 7 areother sensors 17 such as an atmospheric pressure (PA) sensor and an exhaust 02 sensor to supply the ECU with respective electrical signals indicative of detected parameter values. -
Fuel injection valves 19 are arranged in theintake pipe 3 each at a location slightly upstream of anintake valve 18 of a corresponding one of the engine cylinders, and connected with afuel tank 22 through aconduit 20, afuel filter 21, and thefeed pump 14 to be supplied with fuel pressurized by thefeed pump 14. -
Reference numeral 23 denotes a pressure regulating valve, a casing of which has its interior divided by adiaphragm 23b into avacuum chamber 23c and afuel chamber 23d. Thevacuum chamber 23c communicates through avacuum passage 24 with the interior of theintake pipe 3 at a location downstream of thethrottle valve 5, so as to be supplied with a vacuum or negative pressure developed in theintake pipe 3 at a zone downstream of thethrottle valve 5, i.e. a negative pressure prevailing in the vicinity of thefuel injection valves 19, through thevacuum passage 24. On the other hand, thefuel chamber 23d communicates through aconduit 26 with the interior of theconduit 20 extending between thefuel tank 22 and thefuel injection valves 19, at a location between thefuel filter 21 and thefuel injection valves 19, whereby the pressure of fuel being supplied to thefuel injection valves 19 is introduced into thefuel chamber 23d. Avalve body 23a of thepressure regulating valve 23 is secured to thediaphragm 23b at its substantially central portion and urged via thediaphragm 23b by aspring 23e in a valve closing direction. - At the start of the
engine 1, so long as the supply voltage VB supplied from thepower supply source 15 to thefeed pump 14 is lower than a predetermined value, and the fuel pressure within thefuel chamber 23d is low accordingly, thevalve body 23a is seated against avalve seat 23f formed at an open end of aconduit 25 communicating with thefuel tank 22, by the force of thespring 23e urging thevalve body 23a via thediaphragm 23b, to close the open end, thereby rendering thepressure regulating valve 23 inoperative. Therefore, so long as the supply voltage VB of thepower supply source 15 is lower than the predetermined value, the fuel pressure within theconduit 20, i.e. the pressure of fuel being supplied to thefuel injection valves 19 varies with changes in the supply voltage VB supplied from thepower supply source 15 to thefeed pump 14. - After the start of the
engine 1, when the supply voltage VB supplied from thepower supply source 15 to thefeed pump 14 rises above the predetermined value, and the pressure of fuel being supplied from thefeed pump 14 to thefuel injection valves 19 increases accordingly from a value corresponding to the predetermined value of the supply voltage VB, the resulting increased fuel supply pressure to thefuel injection valves 19, i.e. increased fuel pressure within theconduit 20, is introduced to thefuel chamber 23d through theconduit 26, to displace thevalve body 23a away from thevalve seat 23f against the urging force of thespring 23e. As the fuel supply pressure to thefuel injection valves 19 further increases, thevalve seat 23f has its opening area increased to thereby increase the amount of fuel returned to thefuel tank 22 through thevalve 23. If the amount of fuel returned to thefuel tank 22 is thus increased, a corresponding drop occurs in the pressure within theconduit 20. On the other hand, as the fuel supply pressure to thefuel injection valves 19 decreases, thevalve body 23a is displaced by the urging force of thespring 23e in the valve closing direction, with its valve opening area decreased to thereby decrease the amount of fuel returned to thefuel tank 22 through thevalve 23. If the amount of fuel returned to thefuel tank 22 is thus decreased, a corresponding rise occurs in the pressure within theconduit 20. The negative pressure in theintake pipe 3 is supplied to the other side of thediaphragm 23b. Thus, so long as the supply voltage VB supplied from thepower supply source 15 to thefeed pump 14 is higher than the predetermined value, thepressure regulating valve 23 operates to maintain constant the fuel pressure difference between the fuel pressure supplied to the fuel injection valves from the fuel tank and the internal pressure within the intake passage of the engine prevailing in the vicinity of the fuel injection valves. - Each of the
fuel injection valves 19, formed of an on-off type solenoid valve, has its solenoid, not shown, connected to theECU 7 so that when energized by a driving signal from theECU 7, it opens with its valve body, not shown, lifted through a constant stroke and for a period of time corresponding to the duration of the driving signal, as hereinafter referred to. Therefore, so long as the pressure of fuel supplied to thefuel injection valves 19 remains constant and at the same time the fuel pressure difference AP between the fuel supply pressure supplied to thefuel injection valves 19 and the intake pipe (negative) pressure in the vicinity of thefuel injection valves 19 remains constant, the engine is supplied with an amount of fuel corresponding to the time period for which the driving signal is applied to thefuel injection valves 19 from theECU 7, i.e. the duration of the driving signals (the valve opening period). On the other hand, as the fuel supply pressure drops, the engine is supplied with a correspondingly decreased amount of fuel so long as the valve opening period remains constant. - The
ECU 7 comprises an input circuit 7a having functions of shaping waveforms of pulses of input signals from the aforementioned sensors indicative of various operating parameters of theengine 1, shifting voltage levels of the input signals, and converting analog values of the input signals into digital signals, etc., a central processing unit (hereinafter called "the CPU") 7b, memory means 7c for storing various calculation programs to be executed within theCPU 7b, calculated data from theCPU 7b, and calculation data such as a TiCR-TW table, KNe-Ne table, and KPV-VB table, all hereinafter described, and anoutput circuit 7d for supplying driving signals to thefuel injection valves 19. - The fuel supply control system constructed as above operates as follows:
- When the
key switch 13 is turned to connect theterminal 13c with theterminal 13b, supply voltage VB is supplied from thepower supply source 15 to thefeed pump 14 via thekey switch 13, and is also supplied to theECU 7. When thekey switch 13 is further turned so that theterminal 13c is also connected with the terminal 13a, thestarter 12 is actuated to start theengine 1, and a signal indicative of on and off states of thestarter 12 is supplied to theECU 7. - After the
engine 1 is thus started and a signal from theNe sensor 16 indicative of the predetermined crank angles is inputted to theECU 7, theECU 7 determines operating conditions of the engine such as a starting condition on the basis of output signals from the various sensors indicative .of engine operating parameters such as engine coolant temperature TW, supply voltage VB, and on and off states of thestarter 12, and calculates the valve opening period TOUT for thefuel injection valves 19 in accordance with the determined operating conditions of theengine 1. -
- wherein TiCR represents a basic value of the valve opening period TOUT which is applied at the start of the engine, and determined, e.g. based upon the engine coolant temperature TW detected by the TW sensor 11. To be specific, the basic valve opening period value TiCR is read from a TiCR-TW table shown in Fig. 2, for example. As shown in Fig. 2, predetermined values TCR1-TCR5 as the basic valve opening period value are stored and correspond, respectively, to predetermined values TWCR1-TWCR5 of the engine coolant temperature TW, which are set to larger values as the engine coolant temperature TW decreases. When the detected temperature TW value falls between two adjacent ones of the predetermined values TWCR1-TWCR5, the basic valve opening period value TiCR is calculated by an interpolation method.
- KPV represents a supply voltage-dependent correction coefficient according to the invention which is determined in dependence on the supply voltage VB to be supplied from the
power source 15 to thefeed pump 14, e.g., by reading a value of the coefficient KPV corresponding to the supply voltage VB from a KPV-VB table shown in Fig. 5, hereinafter described. - Further, KNe represents an engine rotational speed-dependent correction coefficient applicable at the start of the engine, which is determined in dependence on the engine rotational speed Ne detected by the
Ne sensor 16. To be specific, the coefficient KNe is read from a KNe-Ne table shown in Fig. 3 showing an example of the relationship between the correction coefficient KNe and the engine rotational speed Ne. As shown in Fig. 3, when the detected engine speed Ne is equal to or lower than a predetermined lower limit value Ne1, the value of the coefficient KNe is held at a value KNe1=1, and when the detected engine speed Ne is equal to or higher than a predetermined upper limit value Ne2, the value of the coefficient KNe is held at KNe2=0.5. When the detected engine speed Ne falls between the predetermined lower and upper limit values Ne1 and Ne2, the value of the correction coefficient KNe is calculated by an interpolation method. - Furthermore, TV represents a supply voltage-dependent correction variable for increasing and decreasing the basic valve opening period value TiCR in response to changes in the supply voltage VB supplied from the
power source 15 to thefuel injection valves 19 to drive same, the value of which is, for example, read from a TV-VB table shown in Fig. 4, in response to the supply voltage VB. As shown in Fig. 4, the correction variable TV is set to smaller values as the supply voltage VB increases. For example, when the supply voltage VB is 8,13, and 16 volts, the correction variable TV is set to 1.75, 0.9, and 0.3 ms, respectively. - The supply voltage-dependent correction variable TV is employed to compensate for a delay in the response of the
fuel injection valves 19 due to low supply voltage VB supplied from thepower source 15 to thevalves 19. By employing the correction variable TV, the actual valve opening time period of thefuel injection valves 19 can be made equal to the first term (TiCRxKNexKPV) at the right side of the equation (1) which is obtained when the supply voltage VB has a normal value. On the other hand, the supply voltage-dependent correction coefficient KPV according to the invention is employed to compensate for a shortage of the fuel injection quantity Of due to a small fuel pressure difference AP caused by a change in the supply voltage VB supplied from thepower supply source 15 to thefeed pump 14 at the start of the engine, by increasing the valve opening period of thefuel injection valves 19. Thus, by virtue of the supply voltage-dependent correction variable TV and the supply voltage-dependent correction coefficient KPV, the fuel injection quantity Of per injection of thefuel injection valves 19 can be controlled to a value required at the start of the engine. - Next, a manner of calculation of the supply voltage-dependent correction coefficient KPV according to the invention is described with reference to Fig. 5. Fig. 5 shows a KPV-VB table showing an example of the relationship between the supply voltage-dependent correction coefficient KPV and the supply voltage VB. As shown in Fig. 5, predetermined values KPV1 (e.g. 1.2), KPV2 (e.g. 1.15), KPV3 (e.g. 1.07), and KPV4 (e.g. 1.0) of the coefficient KPV are stored and correspond, respectively, to predetermined values VBP1 (e.g. 6v), VBP2 (e.g. 7v), VBP3 (e.g. 8v), and VBP4 (e.g 9v) of the supply voltage VB, in a manner such that the coefficient KPV is set to smaller values with increase in the supply voltage VB so long as the value of the supply voltage VB is lower than the predetermined value VBP4. When the actual supply voltage VB falls between two adjacent ones of the predetermined values VBP1-VBP4, the value of the correction coefficient KPV is calculated by interpolation. When the supply voltage VB is equal to or higher than the predetermined value VBP4, the value of the correction coefficient KPV is held at 1.0, since the fuel pressure difference AP can be maintained at a constant value by the operation of the
pressure regulating valve 23 which operates to maintain constant the fuel supply pressure to thefuel injection valves 19 through theconduit 20. On the other hand, when the supply voltage VB is lower than the predetermined value VBP4 below which the fuel supply pressure to thefuel injection valves 19, and accordingly the fuel pressure difference AP can decrease substantially in proportion to decrease in the supply voltage VB, the set value of the correction coefficient KPV is applied to the equation (1) whereby the basic valve opening period value TiCR is multiplied by the correction coefficient KPV, thus making it possible to obtain a valve opening period TOUT value appropriate for supplying a required quantity of fuel to the engine at start. - The
ECU 7 supplies thefuel injection valves 19 with driving signals corresponding to the thus calculated valve opening period TOUT, to open same over the time period TOUT. - Incidentally, although in the foregoing embodiment, the basic valve opening period TiCR is set based upon the engine coolant temperature TW, this is not limitative, but the basic valve opening period may be set based upon the engine coolant temperature TW, and one or more operating parameters of the engine such as the engine rotational speed Ne, intake air quantity, and intake pipe absolute pressure PBA, to be corrected by means of the supply voltage-dependent correction coefficient KPV of the invention.
- As described above in detail, according to the fuel supply control method for an internal combustion engine at start, the parameter value VB indicative of the pressure of fuel supplied to the
fuel injection valves 19 is detected, the correction value KPV corresponding to the detected parameter value VB is determined, and the basic valve opening period TiCR set at least based upon the engine temperature TW is corrected by means of the thus determined correction value KPV. Therefore, it is possible to supply a required quantity of fuel to the engine at start even when the fuel pressure difference AP is small between the fuel pressure supplied to thefuel injection valves 19 and the intake passage pressure in the vicinity of thefuel injection valves 19, which is caused by low supply voltage VB supplied from the fuel supplying means 14, to thereby improve the startability and driveability of the engine.
Claims (2)
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP96034/85 | 1985-05-08 | ||
JP60096034A JPS61255234A (en) | 1985-05-08 | 1985-05-08 | Fuel feed control on start of internal-combustion engine |
Publications (2)
Publication Number | Publication Date |
---|---|
EP0206485A1 EP0206485A1 (en) | 1986-12-30 |
EP0206485B1 true EP0206485B1 (en) | 1990-04-11 |
Family
ID=14154155
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
EP86303498A Expired - Lifetime EP0206485B1 (en) | 1985-05-08 | 1986-05-08 | Fuel supply control method for internal combustion engines at start |
Country Status (3)
Country | Link |
---|---|
EP (1) | EP0206485B1 (en) |
JP (1) | JPS61255234A (en) |
DE (2) | DE3670343D1 (en) |
Families Citing this family (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
KR100405682B1 (en) * | 2000-12-30 | 2003-11-14 | 현대자동차주식회사 | An electric management system of gasoline direct injection engine and a method compensating fuel pressure of the same |
Citations (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
EP0053464A2 (en) * | 1980-11-28 | 1982-06-09 | Mikuni Kogyo Co., Ltd. | An electronically controlled fuel injection system |
EP0175162A2 (en) * | 1984-09-19 | 1986-03-26 | Robert Bosch Gmbh | Electronic apparatus for generating an electrical fuel-measuring signal for a combustion engine |
Family Cites Families (7)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US3011486A (en) * | 1956-09-24 | 1961-12-05 | Bendix Corp | Fuel injection system for internal combustion engines |
GB1208570A (en) * | 1967-02-07 | 1970-10-14 | Ass Eng Ltd | Fuel injection systems for internal combustion engines |
JPS5153125A (en) * | 1974-11-05 | 1976-05-11 | Nippon Denso Co | DENSHISHIKINENRYOFUNSHASEIGYOSOCHINO DENATSUHOSEI KAIRO |
JPS5944494B2 (en) * | 1979-12-06 | 1984-10-30 | 日産自動車株式会社 | Electronically controlled fuel injection system for internal combustion engines |
JPS57137633A (en) * | 1981-02-20 | 1982-08-25 | Honda Motor Co Ltd | Fuel feed controller of internal combustion engine |
US4430978A (en) * | 1981-09-28 | 1984-02-14 | The Bendix Corporation | Direct liquid injection of liquid petroleum gas |
JPS6040756A (en) * | 1983-08-12 | 1985-03-04 | Mikuni Kogyo Co Ltd | Fuel injection device in internal-combustion engine |
-
1985
- 1985-05-08 JP JP60096034A patent/JPS61255234A/en active Pending
-
1986
- 1986-05-08 DE DE8686303498T patent/DE3670343D1/en not_active Expired - Fee Related
- 1986-05-08 DE DE1986303498 patent/DE206485T1/en active Pending
- 1986-05-08 EP EP86303498A patent/EP0206485B1/en not_active Expired - Lifetime
Patent Citations (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
EP0053464A2 (en) * | 1980-11-28 | 1982-06-09 | Mikuni Kogyo Co., Ltd. | An electronically controlled fuel injection system |
EP0175162A2 (en) * | 1984-09-19 | 1986-03-26 | Robert Bosch Gmbh | Electronic apparatus for generating an electrical fuel-measuring signal for a combustion engine |
Also Published As
Publication number | Publication date |
---|---|
DE206485T1 (en) | 1987-08-13 |
JPS61255234A (en) | 1986-11-12 |
DE3670343D1 (en) | 1990-05-17 |
EP0206485A1 (en) | 1986-12-30 |
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