JP2007126986A - Controller of fuel pump - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To surely prevent vapor lock from occurring in a fuel feed system without causing cost increase. <P>SOLUTION: When a detected atmospheric pressure PA is equal to or less than a predetermined pressure PAFPCHI (S60), the lowered amount DPAFPC of the detected atmospheric pressure PA from the start of an engine is larger than a predetermined change amount DPAFPCH (S61), or when an evaporated fuel concentration parameter VPRTTL indicating the concentration of the evaporated fuel in purge gas supplied from an evaporated fuel processing device to the engine is larger than a predetermined value VPRFPCHI (S62), a controller of a fuel pump determines that vapor lock occur easily, and drives the fuel pump 10 in a large flow mode (S67). <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a fuel pump control device that pumps fuel in a fuel tank to a fuel injection valve of an internal combustion engine.

  In Patent Document 1, the fuel temperature (first fuel temperature) in the fuel tank and the fuel temperature (second fuel temperature) in the fuel system path close to the fuel injection valve are detected, and the detected first and first temperatures are detected. A control device is shown in which the fuel pump is driven at a higher speed than during normal control when the difference between the two fuel temperatures is equal to or greater than a predetermined value.

Japanese Utility Model 1-339900

The above-described conventional device has been devised by paying attention to the fact that when the difference between the first and second fuel temperatures is large, a vapor lock in which the fuel passage is blocked by fuel vapor is likely to occur.
However, in the above conventional apparatus, two temperature sensors are required, resulting in an increase in cost. Further, in the above-described conventional apparatus, vapor lock due to a decrease in atmospheric pressure is not taken into consideration.

  The present invention has been made in consideration of the above-described points, and an object of the present invention is to provide a fuel pump control device that can more reliably prevent vapor lock in a fuel supply system without causing an increase in cost. .

  In order to achieve the above object, an invention according to claim 1 is directed to an internal combustion engine (1) provided with an evaporative fuel processing device (31 to 33) for supplying an air-fuel mixture containing evaporative fuel generated in a fuel tank (9). ) Is supplied to the engine (1) from the evaporative fuel treatment device (31 to 33) in the control device of the fuel pump (10) for pumping fuel from the fuel tank (9) to the fuel injection valve (6). An evaporative fuel concentration estimating means for estimating an evaporative fuel concentration (VPRTTL) in the air-fuel mixture, and the fuel when the evaporative fuel concentration (VPRTTL) estimated by the evaporative fuel concentration estimating means is higher than a predetermined concentration (VPRFPCHI) And a fuel pump drive means for driving the pump (10) at a rotational speed higher than usual.

  The evaporative fuel concentration estimation means is an air-fuel ratio correction coefficient (set so that the air-fuel ratio detected by the air-fuel ratio detection means (19) provided in the exhaust system (20) of the engine matches the target air-fuel ratio. It is desirable to estimate the fuel vapor concentration (VPRTTL) based on KAF).

  According to a second aspect of the present invention, there is provided a control device for a fuel pump that pumps fuel in a fuel tank to a fuel injection valve of an internal combustion engine, and an atmospheric pressure detecting means for detecting atmospheric pressure (PA), and detected atmospheric pressure. When (PA) is lower than a predetermined pressure (PAFPCHI), or when the detected atmospheric pressure decrease amount (DPAFPC) is larger than a predetermined amount (DPAFPCH), the fuel pump (10) is driven at a higher rotational speed than usual. And a fuel pump drive means.

  The fuel pump (10) is configured to be drivable at a first rotation speed and a second rotation speed higher than the first rotation speed, and the pump driving means has an estimated evaporated fuel concentration of a predetermined value. When it is higher than the concentration, when the detected atmospheric pressure is lower than a predetermined pressure, or when the detected decrease in atmospheric pressure is greater than a predetermined amount, the fuel pump (10) is driven at the second rotational speed. It is desirable.

  According to the first aspect of the present invention, the concentration of the evaporated fuel in the air-fuel mixture supplied from the evaporated fuel processing device to the engine is estimated, and when the estimated evaporated fuel concentration is higher than the predetermined concentration, the fuel pump is normally Driven at a faster rotational speed. Evaporated fuel concentration is estimated in normal air-fuel ratio control. Therefore, it is possible to detect a state where vapor lock is likely to occur without providing a new component such as a temperature sensor or evaporated fuel concentration sensor, and to ensure vapor lock. Can be prevented.

  According to the second aspect of the present invention, when the detected atmospheric pressure is lower than the predetermined pressure, or when the detected decrease amount of the atmospheric pressure is larger than the predetermined amount, the fuel pump is driven at a rotational speed faster than usual. Is done. Therefore, vapor lock in the fuel supply system can be reliably prevented when the vehicle driven by the engine is traveling on the highland or when the vehicle moves from the lowland to the highland.

Embodiments of the present invention will be described below with reference to the drawings.
FIG. 1 is a diagram showing a configuration of an internal combustion engine and a control device thereof according to an embodiment of the present invention. In the figure, an internal combustion engine (hereinafter simply referred to as “engine”) 1 has, for example, four cylinders, and a throttle valve 3 is disposed in the middle of an intake pipe 2 of the engine 1. Further, a throttle valve opening sensor 4 is connected to the throttle valve 3, and an electric signal corresponding to the opening of the throttle valve 3 is output and supplied to an electronic control unit (hereinafter referred to as “ECU”) 5.

  The fuel injection valve 6 is provided for each cylinder in the middle of the intake pipe 2 and slightly upstream of an intake valve (not shown) between the engine 1 and the throttle valve 3. Each fuel injection valve 6 is connected to a fuel pump unit 11 provided in a fuel tank 9 having a sealed structure via a fuel supply pipe 7. A pulsation damper 8 is provided in the fuel supply pipe 7. The fuel pump unit 11 includes a fuel pump 10, a fuel strainer (not shown), and a pressure regulator (not shown) whose reference pressure is atmospheric pressure or tank internal pressure. The ECU 5 is connected to the fuel pump 10 via the drive circuit 12 and performs drive control (rotational speed control) of the fuel pump 10.

  The fuel injection valve 6 is electrically connected to the ECU 5, and the valve opening time is controlled by a signal from the ECU 5. An intake pipe absolute pressure (PBA) sensor 13 for detecting the intake pipe absolute pressure PBA and an intake air temperature (TA) sensor 14 for detecting the intake air temperature TA are mounted downstream of the throttle valve 3 of the intake pipe 2.

An engine speed (NE) sensor 17 for detecting the engine speed is attached around the camshaft or crankshaft (not shown) of the engine 1. The engine speed sensor 17 outputs a pulse (TDC signal pulse) at a predetermined crank angle position every 180 degrees rotation of the crankshaft of the engine 1. An engine coolant temperature sensor 18 that detects the coolant temperature TW of the engine 1 is mounted on the engine body. An oxygen concentration sensor (hereinafter referred to as “LAF sensor”) 19 for detecting the oxygen concentration in the exhaust gas of the engine 1 is provided in the exhaust pipe 20. Detection signals from the sensors 13, 14, 17 to 19 are supplied to the ECU 5.
The ECU 5 is further connected to an atmospheric pressure sensor 22 for detecting the atmospheric pressure PA and a vehicle speed sensor 23 for detecting a traveling speed (vehicle speed) VP of a vehicle driven by the engine 1. To be supplied.

A canister 33 is connected to the fuel tank 9 via a charge passage 31, and the canister 33 is connected to the downstream side of the throttle valve 3 of the intake pipe 2 via a purge passage 32. The canister 33 contains activated carbon for adsorbing the evaporated fuel in the fuel tank 9, and can communicate with the atmosphere via an air passage (not shown). A purge control valve 34 is provided between the canister 33 and the intake pipe 2 in the purge passage 32. The purge control valve 34 is an electromagnetic valve configured such that the flow rate can be continuously controlled by changing the on-off duty ratio (the opening degree of the control valve) of the control signal. It is controlled by the ECU 5.
The charge passage 31, the purge passage 32, the canister 33 and the purge control valve 34 constitute an evaporated fuel processing device.

  The ECU 5 shapes input signal waveforms from various sensors, corrects the voltage level to a predetermined level, and converts an analog signal value into a digital signal value, a central processing circuit (hereinafter referred to as “CPU”). A storage circuit that stores a calculation program executed by the CPU, a calculation result, and the like, and an output circuit that supplies a drive signal to the fuel injection valve 6, the drive circuit 12 of the fuel pump 10, the purge control valve 34, and the like. The

The CPU of the ECU 5 controls the amount of fuel supplied to the engine 1 according to the output signals of various sensors such as the engine speed sensor 17, the intake pipe absolute pressure sensor 13, and the engine coolant temperature sensor 18, and the duty control of the purge control valve 34. I do.
The CPU of the ECU 5 calculates the valve opening time TOUT of the fuel injection valve 6 by the following equation (1).
TOUT = TIM × KAF × K1 + K2 (1)

  TIM is a basic fuel amount, specifically, a basic fuel injection time of the fuel injection valve 6, and is determined by searching a TI map set according to the engine speed NE and the intake pipe absolute pressure PBA. The TI map is set so that the air-fuel ratio of the air-fuel mixture supplied to the engine becomes substantially the stoichiometric air-fuel ratio in the operating state corresponding to the engine speed NE and the intake pipe absolute pressure PBA. That is, the basic fuel amount TIM has a value substantially proportional to the intake air amount (mass flow rate) of the engine 1 per 1 TDC period (time interval between adjacent TDC pulses).

KAF is an air-fuel ratio correction coefficient set according to the output of the LAF sensor 19. The air-fuel ratio correction coefficient KAF is set so that the air-fuel ratio detected by the oxygen concentration sensor 19 matches the target air-fuel ratio.
K1 and K2 are other correction coefficients and correction variables that are calculated according to various engine parameter signals, respectively, and are predetermined values that can optimize various characteristics such as fuel consumption characteristics and engine acceleration characteristics according to engine operating conditions. Set to a value.

  Further, even when the ignition switch is turned on, the CPU of the ECU 5 automatically stops the engine 1 when the predetermined engine stop condition is satisfied (performs idle stop), and restarts the engine 1 when the predetermined restart condition is satisfied. Execute stop / start control.

  The CPU of the ECU 5 performs drive control of the fuel pump 10 as described below. FIG. 2 is a block diagram showing a drive circuit of the motor 10 a of the fuel pump 10, and a duty control signal DFP is output from the ECU 5 and supplied to the drive circuit 12. The drive circuit 12 is supplied with the output voltage VB of the battery when the ignition switch is turned on. The ECU 5 outputs a duty control signal DFP with a duty ratio DUTY of 0% when stopping the motor 10a, and when operating in the small flow rate mode, the ECU 5 has a small flow rate control value DUTL (for example, 66%). When the duty control signal DFP is output and operated in the large flow rate mode, the duty control signal DFP with the duty ratio DUTY of the large flow rate control value DUTH (for example, 100%) is output. The drive circuit 12 outputs a drive voltage VM equal to, for example, 0V (0%), 10.75V (66%), and the battery VB (100%) according to the duty ratio DUTY of the input duty control signal DFP. Thereby, control which switches the rotational speed of the fuel pump 10 to three steps including a stop is performed.

3 and 4 are flowcharts of processing for performing flow rate control (rotational speed control) of the fuel pump 10. This process is executed by the CPU of the ECU 5 every predetermined time (for example, 200 milliseconds).
In step S11, the FFPCHIRQ setting process shown in FIG. 5 is executed. In the FFPCHIRQ setting process, the large flow rate request flag FFPCHIRQ referred to in step S20 of this process is an air-fuel mixture (hereinafter “ It is set in accordance with an evaporative fuel concentration parameter VPRTTL indicating the evaporative fuel concentration in the “purging gas”.

  In step S18, it is determined whether or not a fail safe processing flag (hereinafter referred to as “FSA flag”) FFSPFPCZN set in the processing of FIG. 6 is “1”. If the answer is affirmative (YES), the value of the upcount timer TISFPC is set to “0” (step S21), and the flow control parameter FPCZN is set to “3” (step S37). When the flow control parameter FPCZN is set to “3”, the duty ratio DUTY of the drive control signal of the fuel pump 10 is set to the large flow control value DUTH so that the operation mode of the fuel pump 10 becomes the large flow rate mode.

  When FFSPFPCZN = 0 in step S18, it is determined whether or not the value of the upcount timer T01IGPON is smaller than a predetermined time TMIGONFPC (for example, 2 seconds) (step S19). The upcount timer T01IGPON is a timer that measures the time from when the ignition switch is turned on. If the answer to step S19 is affirmative (YES), that is, if the predetermined time TGIMONFPC has not elapsed after the ignition switch is turned on, the process proceeds to step S21. Therefore, the duty ratio DUTY is set to the large flow rate control value DUTH.

  If T01IGPONFPC ≧ TMIGONFPC in step S19, it is determined whether or not the large flow rate request flag FFPCHIRQ set in step S11 is “1” (step S20). When FFPCHIRQ = 1 and the large flow rate mode is requested, the process proceeds to step S21. On the other hand, when the large flow rate request flag FFPCHIRQ is “0”, the process proceeds to step S22 (FIG. 4) to determine whether or not the engine stop flag FMEOF is “1”. The engine stop flag FMEOF is set to “1” when the engine is stopped with the ignition switch turned on. If the answer to step S22 is negative (NO), and the engine is operating, the value of the upcount timer TISFPC is set to “0” (step S23), and the fuel cut flag FMADECFC is “1”. Is determined (step S24). The fuel cut flag FMADECFC is set to “1” when the fuel cut (fuel supply cut-off) operation is performed.

  If the answer to step S24 is negative (NO) and the vehicle is operating normally, it is determined whether or not the vehicle speed VP is higher than a first predetermined vehicle speed VFPOFFL (for example, 10 km / h) (step S27). If the answer is affirmative (YES), it is determined whether or not an air-conditioning clutch flag FACCL is “1” (step S29). The air conditioning clutch flag FACCL is set to “1” when the clutch that drives the air conditioner is engaged. If the answer to step S29 is negative (NO), it is determined whether or not the engine speed NE is higher than a predetermined engine speed NEFPOFF (eg, 3000 rpm) (step S30).

  If the answer to step S30 is negative (NO), the downcount timer TFPOFF is set to a first predetermined time TMFPOFF (for example, 0.5 seconds) and started (step S32). On the other hand, when the answer to step S27 is negative (NO) or the answer to step S29 or S30 is affirmative (YES), the downcount timer TFPOFF is set to a second predetermined time TFFPOFF2 (for example, 25 seconds) longer than the first predetermined time TMFPOFF. Set and start (step S31). The downcount timer TFPOFF is referred to in step S26.

  After execution of step S31 or S32, the process proceeds to step S33, and it is determined whether or not the value of the upcount timer T1SAST is equal to or longer than a predetermined time TMASTFPC (for example, 1 second). The up-count timer T1SAST is a timer that measures an elapsed time from when the engine 1 is started. If the answer to step S33 is affirmative (YES), it is determined whether or not the value of the upcount timer TACRFPC is equal to or longer than a predetermined time TMACRFPC (for example, 2 seconds) (step S34). The up-count timer TACRFPC is a timer that is set to “0” in step S38 when the engine 1 is stopped and measures the elapsed time after restart. If the answer to step S34 is affirmative (YES), it is determined whether or not an injection amount parameter NTI indicating a fuel injection amount (fuel injection time) per unit time is equal to or greater than a predetermined amount NTIFPCH (for example, 28 sec / min). To do.

  If the answer to step S35 is negative (NO), the flow control parameter FPCZN is set to “2” (step S36). On the other hand, if the answer to step S33 or S34 is negative (NO) or the answer to step S35 is affirmative (YES), the flow control parameter FPCZN is set to “3” (step S37).

  If FMADECFC = 1 in step S24 and the fuel cut operation is being performed, it is determined whether or not the vehicle speed VP is lower than a second predetermined vehicle speed VFPOFFH (for example, 120 km / h) higher than the first predetermined vehicle speed VFPOFFL (step S25). ). When the answer is negative (NO), the process proceeds to step S32, and when the answer is positive (YES), whether or not the value of the downcount timer TFPOFF started in step S31 or S32 is “0”. Is determined (step S26). Since this answer is negative (NO) at first, the process proceeds to step S33, and when TFPOFF = 0, the flow control parameter FPCZN is set to “0”. When the flow control parameter FPCZN is set to “0”, the control duty ratio DUTY of the fuel pump 10 is set to “0”, and the operation of the fuel pump 10 is stopped.

  When FMEOOF = 1 in step S22 and the engine is stopped, the value of the upcount timer TACRFPC is set to “0” (step S38), and the value of the upcount timer TISFPC is set to “0”. (Step S40), the flow control parameter FPCZN is set to “0” (Step S43).

FIG. 5 is a flowchart of the FFPCHIRQ setting process executed in step S11 of FIG.
In step S51, it is determined whether or not the initialization flag FPAINIFPC is “1”. Since this answer is negative (NO) at the beginning (immediately after engine start), the process proceeds to step S52, and the detected atmospheric pressure PA at that time is stored as the initial atmospheric pressure PAINIFPC. In step S53, the initialization flag FPAINIFPC is set to “1”, and the process proceeds to step S54. After step S53 is executed, the answer to step S51 is affirmative (YES), and the process proceeds from step S51 to step S54.

In step S54, the atmospheric pressure change amount DPAFPC indicating the amount of decrease from the initial atmospheric pressure PAINIFPC is calculated by the following equation (2).
DPAFPC = PAINIFPC-PA (2)
In step S55, it is determined whether or not the start flag FFENGST is “1”. The start flag FFENGST is set to “1” when the ignition switch is turned on and the engine is started, and is returned to “0” when the start is completed. If the start flag FFENGST is “1” in step S55 and the engine 1 is being started, the TFMCHI table is searched according to the engine coolant temperature TW to calculate the holding time TMFPCHI (step S56). The TMFPCHI table is set so that the retention time TMFPCHI becomes longer as the engine coolant temperature TW increases. At the time of engine start, the evaporated fuel concentration parameter VPRTTL is set to “0”, is updated according to the value of the subsequent air-fuel ratio correction coefficient KAF, and gradually converges to a value indicating the actual evaporated fuel concentration. The higher the engine cooling water temperature TW, the higher the evaporated fuel concentration in the purge gas. Therefore, the time required for the evaporated fuel concentration parameter VPRTL to accurately indicate the actual evaporated fuel concentration becomes longer. Accordingly, immediately after the engine is started, the holding time TMFPCHI, which is the time for holding the fuel pump 10 in the large flow rate mode, is set longer as the engine cooling water temperature TW becomes higher.

In step S57, the downcount timer TFPCHI is set to the holding time TFMCHI to start, and the process proceeds to step S58. If FFENGST = 0 in step S55, the process immediately proceeds to step S58.
In step S58, it is determined whether or not the value of the timer TFPCHI started in step S57 is “0”. If the answer is affirmative (YES), it is determined whether or not the vehicle speed VP is equal to or higher than a predetermined vehicle speed VFPCNV (for example, 5 km / h) (step S59). If the answer is negative (NO), it is determined whether or not the atmospheric pressure PA is equal to or lower than a predetermined pressure PAFPCHI (for example, 73 kPa (550 mHg)) (step S60).

  When the answer to step S58 is negative (NO) or the answer to step S59 or S60 is affirmative (YES), that is, immediately after restart after idling stop, when the vehicle speed is high, or when traveling at high altitude Sets the large flow rate request flag FFPCHIRQ to "1" and operates the fuel pump 10 in the large flow rate mode (step S67).

  If PA> PAFPCHI in step S60, it is determined whether or not the atmospheric pressure change amount DPAFPC calculated in step S54 is greater than a predetermined change amount DPAFPCH (for example, 3.3 kPa (25 mmHg)) (step S61). If this answer is negative (NO), it is determined whether or not an evaporative fuel concentration parameter VPRTTL indicating an evaporative fuel concentration in the purge gas supplied from the canister 33 is larger than a predetermined value VPRFPCHI (for example, 18 times) (step). S62).

  If the answer to step S61 or S62 is affirmative (YES), that is, the vehicle moves to a higher altitude than the engine starting point and the amount of decrease in atmospheric pressure is large or the evaporated fuel concentration in the purge gas is high, the downcount timer TFPCMID is set for a predetermined time TFMCCMID. (For example, 430 seconds) is set and started, and the process proceeds to step S67.

  If the answer to step S62 is negative (NO), it is determined whether or not the value of the timer TFPCMID started in step S64 is “0” (step S65). While TFPCMID> 0, the process proceeds to step S67 and the large flow rate mode request is maintained. When the value of the timer TFPCMID becomes “0”, the process proceeds from step S65 to step S66, and the large flow rate request flag FFPCHIRQ is set to “0”.

  According to the processing of FIG. 5, immediately after restart after idling stop, the estimation of the evaporated fuel concentration in the purge gas (calculation of the evaporated fuel concentration parameter VPRTTL) and the estimation of the reduced pressure boiling effect based on the amount of decrease in atmospheric pressure are performed accurately. Since it cannot be performed, the large flow rate mode is continued for the holding time TMFPCHI corresponding to the engine coolant temperature TW. Further, at high altitudes (PA ≦ PAFPCHI, DPAFPC> DPAFPCH), vapor lock is likely to occur due to the boiling under reduced pressure, and vapor lock is also likely to occur when the amount of evaporated fuel generated in the fuel tank is large (VPRTTL> VPRFPCHI). The fuel pump 10 is driven in the large flow rate mode. As a result, vapor lock, and thus lean air-fuel ratio and unnecessary warning display resulting therefrom can be prevented, and stability of engine rotation during idling can be improved. Further, when the vehicle speed is high (VP ≧ VFPCNV), the operating noise of the fuel pump 10 is not noticeable due to running noise, so the fuel pump 10 is driven in the large flow rate mode, and the air-fuel ratio is prevented from becoming lean.

  In other cases, the fuel pump 10 is not driven in the large flow rate mode, so that it is possible to prevent the operating sound of the fuel pump 10 from causing discomfort to the vehicle occupant in an idle stop state, for example.

FIG. 6 is a flowchart of processing for setting the FSA flag FFSPFPCZN referred to in step S18 of FIG. This process is executed at predetermined intervals by the CPU of the ECU 5.
In step S71, it is determined whether or not a failure of the intake pipe absolute pressure sensor 13 is detected. If the answer is negative (NO), it is determined whether or not a failure of the engine speed sensor 17 is detected. (Step S72). If the answer to step S72 is negative (NO), it is determined whether or not a failure of the engine coolant temperature sensor 18 has been detected (step S73). If the answer is negative (NO), atmospheric pressure It is determined whether or not a failure of the sensor 22 has been detected (step S74). If the answer to step S74 is negative (NO), it is determined whether or not a failure of the vehicle speed sensor 23 has been detected (step S75). If the answer is negative (NO), the evaporated fuel processing device. It is determined whether or not a failure has been detected (step S76). If the answer to step S76 is negative (NO), it is determined whether or not a failure of the drive circuit 12 of the fuel pump 10 has been detected (step S77).

  When the answer to step S77 is negative (NO), the FSA flag FFSPFPCZN is set to “0” (step S78), while when any answer of steps S71 to S77 is affirmative (YES), FSA The flag FFSPFPCZN is set to “1” (step S79). Thereby, when a failure of the various sensors, the evaporated fuel processing apparatus, or the drive circuit 12 is detected, the fuel pump 10 is driven in the large flow rate mode (FIG. 3, Step S18, FIG. 4, Step S37), It is possible to prevent the occurrence of a vapor lock due to a failure of the sensor or the like, and thus the instability of the idle speed.

  Next, the calculation process of the fuel vapor concentration parameter VPRTTL will be described with reference to FIGS. The fuel vapor concentration parameter VPRTTL is calculated according to the learning values KREF and KREFX of the air-fuel ratio correction coefficient KAF calculated according to the output of the LAF sensor 19.

  FIG. 7 is a flowchart of a process for calculating learning values KREF and KREFX of the air-fuel ratio correction coefficient KAF. This process is executed in synchronism with the generation of the TDC pulse during execution of the air-fuel ratio feedback control according to the output of the LAF sensor 19. In this process, the first learning value KREF is calculated during execution of purge of evaporated fuel (supply to the intake pipe 2), and the second learning value KREFX is calculated during purge stop.

In step S131, it is determined whether or not a purge stop flag FPGDLY is “1”. The purge stop flag FPGDLY is set to “1” when the purge of the evaporated fuel is stopped in order to calculate the second learning value KREFX.
When FPGDLY = 0 and the purge is not stopped, it is determined whether or not the learning permission flag FKRFCND is “1” (step S132). The learning permission flag FKRFCND is set to “1” when the engine is in an operating state in which the calculation of the learning value KREF or KREFX is permitted. When FKRFCND = 1, the first learning value KREF is calculated by the following equation (3) (step S133).
KREF = CREF × KAF + (1−CREF) × KREF (3)
Here, CREF is an annealing coefficient set to a value between 0 and 1, and KREF on the right side is a previous calculated value.

  In step S134, limit processing of the first learning value KREF calculated in step S133 is performed. That is, when the first learning value KREF is smaller than the predetermined lower limit value KREFLMTL, the first learning value KREF is set to the predetermined lower limit value KREFLMTL, and when the first learning value KREF is larger than the predetermined upper limit value KREFLMTH, The value KREF is set to the predetermined upper limit value KREFLMTH, and when the first learning value KREF is between the predetermined upper and lower limit values KREFLMTH and KREFLMTL, the value calculated in step S33 is maintained. Thereafter, the KREFX update flag FKREFX is set to “0” (step S142), and this process ends.

  If FPGDLY = 1 and purge is stopped in step S131, it is determined whether or not the engine speed NE is higher than a predetermined upper limit speed NKREFXH (for example, 4000 rpm) (step S135). If this answer is affirmative (YES), the process proceeds to step S142. When the engine speed NE is less than or equal to the predetermined upper limit speed NKREFXH, it is determined whether or not the value of the elapsed time timer T10MSACR after start is greater than a predetermined time TMKREFXB (for example, 20 seconds) (step S136). If the answer is no (NO), the process immediately proceeds to step S138. When T10MSACR> TMKREFXB, it is determined whether or not the KREFX learned flag FKREFXBU is “1” (step S137). The KREFX learned flag FKREFXBU is set to “1” when the calculation of the second learning value KREFX is first completed after the battery is removed and the previous learning value is lost. If the answer to step S137 is negative (NO), and the calculation of the second learning value KREFX is not completed, the process immediately proceeds to step S141. When FKREFXBU = 1 and the calculation of the second learning value KREFX is completed, the process proceeds to step S138.

  In step S138, it is determined whether or not the intake air temperature TA is higher than a predetermined intake air temperature TAREF (for example, 80 ° C.). If the answer is negative (NO), it is determined whether or not the intake pipe absolute pressure PBA is higher than a predetermined lower limit value PBAREFXL (for example, 21.3 kPa (160 mmHg)) (step S139). If the answer is affirmative (YES), it is determined whether or not the intake pipe absolute pressure PBA is lower than a predetermined upper limit value PBAREFXH (for example, 74.6 kPa (560 mmHg)) (step S140). When the answer to step S140 is affirmative (YES), the process proceeds to step S141, while when the answer to step S138 is affirmative (YES), or when the answer to step S139 or S140 is negative (NO), the step S142 is performed. Proceed to

In step S141, it is determined whether or not the learning permission flag FKRFCND is “1”. If the answer to step S141 is negative (NO), the process proceeds to step S142. When FKRFCND = 1 and learning value calculation is permitted, the second learning value KREFX is calculated by the following equation (4).
KREFX = CREFX × KAF + (1−CREFX) × KREFX (4)
Here, CREFX is an annealing coefficient set to a value between 0 and 1, and KREFX on the right side is a previously calculated value.

  In step S144, limit processing of the second learning value KREFX calculated in step S143 is performed. That is, when the second learning value KREFX is smaller than the predetermined lower limit value KRFXLLML, the second learning value KREFX is set to the predetermined lower limit value KRFXLMTL, and when the second learning value KREFX is larger than the predetermined upper limit value KRFXLMTTH, The value KREFX is set to the predetermined upper limit value KRFXLMH, and when the second learning value KREFX is between the predetermined upper and lower limit values KRFXLMH, KRFXLMTL, the value calculated in step S143 is maintained. Thereafter, the KREFX update flag FKREFX is set to “1” (step S145), and this process ends.

  FIG. 8 is a flowchart of processing for setting a flag referred to in the processing of FIG. 10 described later. This process is executed every predetermined time (for example, 10 milliseconds). In the process of FIG. 8, specifically, an addition flag FKAFEVP, a subtraction flag FKAFEVM, and a deviation calculation flag KAFEVC are set.

  In step S171, the DKAFEVXH table shown in FIG. 9A is searched according to the intake air flow rate QAIR, and the upper determination deviation DKAFEVXH is calculated. The DKAFEVXH table is set so that the upper determination deviation DKAFEVXH decreases as the intake air flow rate QAIR increases. The intake air flow rate QAIR is calculated by multiplying the basic fuel amount TIM by the engine speed NE and a conversion coefficient.

  In step S172, the DKAFEXL table shown in FIG. 9B is searched according to the intake air flow rate QAIR, and the lower determination deviation DKAFEVXL is calculated. The DKAFEVXL table is set such that the lower determination deviation DKAFEVXL decreases as the intake air flow rate QAIR increases.

  In step S175, it is determined whether or not the air-fuel ratio correction coefficient KAF is smaller than a value obtained by subtracting the lower determination deviation DKAFEXL from the second learning value KREFX (step S175). If this answer is affirmative (YES) and the air-fuel ratio correction coefficient KAF is relatively largely deviated to the lean side from the second learning value KREFX, it is determined whether or not the rich air-fuel ratio flag FKACTR is “1”. Determination is made (step S176). The rich air-fuel ratio flag FKACTR is set to “1” when the air-fuel ratio detected by the LAF sensor 19 is on the richer side than the theoretical air-fuel ratio.

  If the answer to step S176 is affirmative (YES) and the detected air-fuel ratio is richer than the stoichiometric air-fuel ratio, the addition flag FKAFEVP is set to “1”, and the subtraction flag FKAFEVM and the deviation calculation flag FKAFEVC are both “0”. "(Step S177). If FKAACTR = 0 in step S176 and the detected air-fuel ratio is not richer than the stoichiometric air-fuel ratio, the addition flag FKAFEVP, the subtraction flag FKAFEVM, and the deviation calculation flag FKAFEVC are all set to “0” (step S180).

  If KAF ≧ (KREFX−DKAFEVXL) in step S175, it is determined whether or not the air-fuel ratio correction coefficient KAF is greater than the value obtained by adding the upper determination deviation DKAFEVXH to the second learning value KREFX (step S178). If this answer is affirmative (YES) and the air-fuel ratio correction coefficient KAF is relatively largely deviated to the rich side from the second learning value KREFX, it is determined whether or not the lean air-fuel ratio flag FKACTL is “1”. A determination is made (step S179). The lean air-fuel ratio flag FKACTL is set to “1” when the air-fuel ratio detected by the LAF sensor 19 is leaner than the stoichiometric air-fuel ratio.

  If the answer to step S179 is affirmative (YES) and the detected air-fuel ratio is leaner than the stoichiometric air-fuel ratio, the subtraction flag FKAFEVM is set to “1”, and the addition flag FKAFEVP and the deviation calculation flag FKAFEVC are both “0”. "(Step S181). If FKACTL = 0 in step S179, the process proceeds to step S180.

  If the answer to step S178 is negative (NO) and the air-fuel ratio correction coefficient KAF is in the vicinity of the second learning value KREFX, it is determined whether or not the first learning value KREF is smaller than the second learning value KREFX. (Step S182). If this answer is affirmative (YES), it is determined whether or not the air-fuel ratio correction coefficient KAF is smaller than the second learning value KREFX (step S183). If this answer is affirmative (YES), it is determined whether or not a rich air-fuel ratio flag FKAACTR is “1” (step S184). If the answer is affirmative (YES), the addition flag FKAFEVP and the subtraction flag FKAFEVM are set to “0”, and the deviation calculation flag FKAFEVC is set to “1” (step S185). If the answer to step S183 or S184 is negative (NO), the addition flag FKAFEVP, the subtraction flag FKAFEVM, and the deviation calculation flag FKAFEVC are all set to “0” (step S188).

  If KREF ≧ KREFX in step S182, the process proceeds to step S186, and it is determined whether or not the air-fuel ratio correction coefficient KAF is greater than the second learning value KREFX. If the answer is affirmative (YES), it is determined whether or not a lean air-fuel ratio flag FKACTL is “1” (step S187). If the answer to step S187 is affirmative (YES), the addition flag FKAFEVP and the subtraction flag FKAFEVM are set to “0”, and the deviation calculation flag FKAFEVC is set to “1” (step S189). If the answer to step S186 or S187 is negative (NO), the process proceeds to step S188.

  According to the process of FIG. 8, when the air-fuel ratio correction coefficient KAF is relatively large and deviates from the second learning value KREFX and the detected air-fuel ratio is on the rich side, the concentration of evaporated fuel in the purge gas increases. The addition flag FKAFEVP is set to “1” (step S177). Further, when the air-fuel ratio correction coefficient KAF is relatively largely deviated from the second learning value KREFX and the detected air-fuel ratio is on the lean side, it is determined that the evaporated fuel concentration in the purge gas has decreased, The subtraction flag FKAFEVM is set to “1” (step S181). Further, the air-fuel ratio correction coefficient KAF is in the vicinity of the second learning value KREFX, the first learning value KREF is smaller than the second learning value KREFX, the air-fuel ratio correction coefficient KAF is smaller than the second learning value KREFX, and the detected air-fuel ratio Is on the rich side, it is determined that the evaporated fuel concentration in the purge gas has increased by an amount corresponding to the deviation (KREFX−KREF) between the first learning value KREF and the second learning value KREFX, and the deviation calculation flag FKAFEVC is set. It is set to “1” (step S185). Alternatively, the air-fuel ratio correction coefficient KAF is close to the second learning value KREFX, the first learning value KREF is greater than or equal to the second learning value KREFX, the air-fuel ratio correction coefficient KAF is greater than the second learning value KREFX, and the detected air-fuel ratio Is on the lean side, the deviation (KREFX−KREF) is a negative value (or “0”), and it is determined that the fuel vapor concentration has decreased by an amount corresponding to this negative deviation, and the deviation calculation flag FKAFEVC Is set to “1” (step S189).

FIG. 10 is a flowchart of a process for calculating the evaporated fuel concentration parameter VPRTTL. This process is executed every predetermined time (for example, 10 milliseconds).
In step S151, it is determined whether or not the feedback control flag FAFFBX is “1”. The feedback control flag FAFFBX is set to “1” when the air-fuel ratio feedback control for calculating the air-fuel ratio correction coefficient KAF according to the output of the LAF sensor 19 is executed. If the answer to step S151 is affirmative (YES), it is determined whether or not the purge flow rate QPGC is “0” (step S152). The purge flow rate QPGC is a parameter indicating the flow rate of the purge gas supplied to the intake pipe 2 via the purge passage 32 during the purge execution. The purge flow rate QPGC is a parameter between the intake air flow rate QAIR of the engine 1, the atmospheric pressure PA, and the intake pipe absolute pressure PBA. It is calculated by a process (not shown) according to the differential pressure or the like.

  When the answer to step S152 is negative (NO), that is, when the air-fuel ratio feedback control and the evaporated fuel purge are executed, the downcount timer TVPRTTLD is set to a predetermined time TMVPRTLD (for example, 10 seconds) and started. (Step S157).

In step S158, it is determined whether or not the addition flag FKAFEVP is “1”. If the answer to step S158 is affirmative (YES), the vapor amount parameter VPRT is calculated by the following equation (5) (step S159). Thereafter, the process proceeds to step S166.
VPRT = VPRTTL + DVPRTLP (5)
Here, VPRTTL is a previously calculated value of the evaporated fuel concentration parameter, and DVPRTLPL is a predetermined addition term.

If FKAFEVP = 0 in step S158, it is determined whether or not the subtraction flag FKAFEVM is “1” (step S160). If the answer to step S160 is affirmative (YES), a vapor amount parameter VPRT is calculated by the following equation (6) (step S161). Thereafter, the process proceeds to step S166.
VPRT = VPRTTL-DVPRTLM (6)
Here, VPRTTL is a previously calculated value of the evaporated fuel concentration parameter, and DVPRTTLM is a predetermined subtraction term.

If FKAFEVM = 0 in step S160, it is determined whether or not the deviation calculation flag FKAFEVC is “1”. If the answer to step S162 is affirmative (YES), the first learning value KREF and the second learning value KREFX calculated in the process of FIG. 7 are applied to the following equation (7) to calculate a learning value deviation DKREFX. (Step S163).
DKREFX = KREFX-KREF (7)

In step S164, the vapor amount parameter VPRT is calculated by applying the learning value deviation DKREFX to the following equation (8). Thereafter, the process proceeds to step S166.
VPRT = VPRTTL + DKREFX × CAFEV (8)
Here, VPRTTL is the previous calculated value of the fuel vapor concentration parameter, and CAFEV is a predetermined thinning coefficient set to 0.03515, for example.

When FKAFEVC = 0 in step S162, the vapor amount parameter VPRT is set to the previous calculated value VPRTTL of the evaporated fuel concentration parameter (step S165), and the process proceeds to step S166.
On the other hand, when the answer to step S151 is negative (NO) or the answer to step S152 is affirmative (YES), that is, when the air-fuel ratio feedback control or the purge of evaporated fuel is not executed, the process proceeds to step S153, and step S157 It is determined whether or not the value of the downcount timer TVPRTTLD started at is “0”. At first, this answer is negative (NO), so the vapor amount parameter VPRT is set to the previous calculated value VPRTTL of the evaporated fuel concentration parameter (step S154), and the process proceeds to step S166. When the value of the timer TVPRTTLD becomes “0”, the process proceeds from step S153 to step S155, and similarly to step S157, the timer TVPRTTLD is set to TMVPRTLD for a predetermined time and started. In the subsequent step S156, the vapor amount parameter VPRT is calculated by the following equation (9). Thereafter, the process proceeds to step S166.
VPRT = VPRTTL−DVPRTLD (9)
Here, VPRTTL is a previously calculated value of the evaporated fuel concentration parameter, and DVPRTLD is a predetermined forced subtraction term.

  In step S166, it is determined whether or not the vapor amount parameter VPRT is equal to or smaller than a predetermined upper limit value VPRTLMT. If the answer to step S166 is affirmative (YES), the evaporated fuel concentration parameter VPRTTL is set to the vapor amount parameter VPRT ( Step S167). When the vapor amount parameter VPRT is larger than the predetermined upper limit value VPRTLMT, the evaporated fuel concentration parameter VPRTL is set to the predetermined upper limit value VPRTLMT (step S168). Thereafter, this process is terminated.

  According to the processing of FIGS. 7, 8, and 10, when the air-fuel ratio correction coefficient KAF is relatively largely deviated from the second learning value KREFX, it is determined that the evaporated fuel concentration is relatively greatly increased or decreased. Then, the fuel vapor concentration parameter VPRTTL is updated so as to increase or decrease relatively large (FIG. 10, steps S159 and S161). Further, when the air-fuel ratio correction coefficient KAF is in the vicinity of the second learning value KREFX, it indicates that the concentration of the evaporated fuel in the purge gas is low. Therefore, a learning value deviation that is a deviation between the first learning value KREF and the second learning value KREFX. The evaporated fuel concentration parameter VPRTTL is updated so as to increase or decrease relatively small by a value obtained by multiplying DKREFX (= KREFX−KREF) by the thinning coefficient CAFEV (FIG. 10, step S164). Therefore, the evaporated fuel concentration parameter VPRTTL updated in this way can be used as a parameter indicating the evaporated fuel concentration in the purge gas.

  The present invention is not limited to the embodiment described above, and various modifications can be made. For example, in the above-described embodiment, the determination based on the atmospheric pressure PA (steps S60 and S61) and the determination based on the evaporated fuel concentration parameter VPRTTL (step S62) in the determination process (step S62) of whether or not the high flow rate mode should be performed. However, only one of them may be performed.

  Further, in the above-described embodiment, the fuel pump 10 uses an operation mode (rotational speed) that can be switched between two stages of a small flow mode and a large flow mode. However, the present invention is not limited to this. What can be switched more than the stage is also applicable.

It is a figure which shows the structure of the internal combustion engine and its control apparatus concerning one Embodiment of this invention. It is a figure which shows the circuit structure which drives the motor of a fuel pump. It is a flowchart of the drive control process of a fuel pump. It is a flowchart of the drive control process of a fuel pump. It is a flowchart of the process which sets the flag (FPHIRQ) referred by the process of FIG. It is a flowchart of the process which sets the flag (FSPFPCZN) referred by the process of FIG. It is a flowchart of the process which calculates the learning value (KREF, KREFX) of an air fuel ratio correction coefficient (KAF). It is a flowchart of the process which sets the flag referred by the process of FIG. It is a figure which shows the table used by the process of FIG. It is a flowchart of the process which calculates the parameter (VPRTTL) which shows the evaporative fuel density | concentration in purge gas.

Explanation of symbols

1 Internal combustion engine 5 Electronic control unit (evaporated fuel concentration estimation means, pump drive means)
6 Fuel injection valve 7 Fuel supply pipe 9 Fuel tank 10 Fuel pump 12 Drive circuit (pump drive means)
19 Oxygen concentration sensor (air-fuel ratio detection means)
22 Atmospheric pressure sensor (atmospheric pressure detection means)
31 Charge passage (evaporative fuel treatment device)
32 Purge passageway (evaporative fuel treatment device)
33 Canister (evaporative fuel treatment device)

Claims (2)

In a control device for a fuel pump that pumps fuel from the fuel tank to a fuel injection valve of an internal combustion engine provided with an evaporative fuel processing device that supplies an air-fuel mixture containing evaporative fuel generated in the fuel tank,
An evaporative fuel concentration estimating means for estimating an evaporative fuel concentration in an air-fuel mixture supplied to the engine from the evaporative fuel processing device;
Fuel pump control means comprising fuel pump drive means for driving the fuel pump at a rotational speed faster than usual when the fuel vapor concentration estimated by the fuel vapor concentration estimating means is higher than a predetermined concentration. apparatus. In a control device for a fuel pump that pumps fuel in a fuel tank to a fuel injection valve of an internal combustion engine,
Atmospheric pressure detection means for detecting atmospheric pressure;
Fuel pump driving means for driving the fuel pump at a rotational speed faster than normal when the detected atmospheric pressure is lower than a predetermined pressure or when the detected amount of decrease in the atmospheric pressure is larger than a predetermined amount. A fuel pump control device.

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